Title of Invention	OXYGEN-SCAVENGING RESIN COMPOSITIONS WITH LOW HAZE AND METHOD FOR PRODUCING THE SAME
Abstract	A resin composition comprising: a film-forming polyester; and from 50 to 2.500 parts by weight of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such that particles of less than about 25 microns in size are present, but do not exceed a concentration defined by the formUla ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter. ¥CN

Title of Invention

OXYGEN-SCAVENGING RESIN COMPOSITIONS WITH LOW HAZE AND METHOD FOR PRODUCING THE SAME

Abstract

A resin composition comprising: a film-forming polyester; and from 50 to 2.500 parts by weight of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such that particles of less than about 25 microns in size are present, but do not exceed a concentration defined by the formUla ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter. ¥CN

Full Text	OXYGEN-SCAVENGING RESIN COMPOSITIONS AND CONTAINERS HAVING LOW HAZE AND RELATED METHODS BACKGROUND OF THE INVENTION Thermoplastic resins such as polyethylene terephthalate (PET) are Commonly lised to manufacture packaging materials. PET processed under the right conditions produces high strength articles with excellent gas barrier properties. Foods, beverages, arid medicines can deteriorate or Spoil if exposed to oxygen. To improve shelf life and flavor retention of products such as foods, beverages, and medicines, therefore, the barrier protection provided by PET is often supplemented with additional layers of packaging material or with the addition of oxygen scavengers. Adding a layer of gas barrier film is known as passive-barrier packaging. Ethylvinyl alcolhol (EVOH), Polyvinylidene dichldride (PVDC), and Nylon MXD6, are examples of films commonly used for this purpose due to their excellent oxygen barrier properties. Using distinct layers of differing materials is not preferred, however, because it adds cost to packaging construction and does not reduce the levels of oxygen already present in the package. Adding oxygen scavengers to the PET resin is known as active-barrier packaging. This approach to protecting oxygen-sensitive products is tvvo-fold; the packaging prevents oxygen from reaching the product from the outside, arid also absorbs some of the oxygen present in the container and frorii within the polymer matrix. In some applications, small packets or sachets containing oxygen scavengers are added to the packaging container and he next to the food. Sachets are generally limited to solid foods, where the sachet can be readily removed from the foodstuff arid hot accidentally ingested. ...... .. - ... .. \ .., Construction of the sachets and the cumbersome nature of their introduction into the package result in increased costs. One way to overcome the disadvantages of sachets is to incorporate the scavenger direcdy into the wall of the food package. This can be done by placing the scavenger throughout the scavenger wall or placing the scavenger contents which migrates into the polymer and contacts the scavenging composition. The use of scavenging powders in clear packages has previously been limited by aesthetics, particularly haze and color. High loadings of iron powder, on the order of 500 - 5000 parts per "million, are typically required to obtain sufficient oxygen absorption. Conventional wisdom and prior art teaches the practitioner to use the highest amount of scavenging surface area possible so that the efficiency and capacity is increased and the amount of iron added is minimized. In practice, this means a large number of small particles. Unfortunately, previous attempts at preparing resin compositions comprising high levels of small particles of iron for use in clear packages have resulted in packages with poor optical properties. This is particularly true vvhen the resin composition is stretched or oriented to any degree in forming the final article, such as in polyester bottles. Typically, bottles prepared from such resin compositions are translucent. Haze values for these bottles are generally high, and clarity is lacking. Thus, there remains a heed for packaging materials having acceptable visual aspects and comprising oxygen scavenging resin compositions. This invention relates to an oxygen-scavenging resin composition having utility in packaging and other applications. More specifically, this invention relates to a film-forming, oxygen-scavenging polyester resin composition having low haze. The present invention also relates to a container having effective oxygen-scavenging functionality and low haze. The present invention further relates to a method for incorporating high levels of oxygen-scavenging particles into a film-forming polyester resin composition with low haze. BRIEF SUMMARY OF THE INVENTION , In general the present invention provides a resin composition comprising: a film-forming polyester; and an effective amount of oxygen-scavenging particles comprising at least qne oxygea-seav^nging element; wherein the particles have a particle size distribution such that particles of less (6.0 x 107 particles * T) per cubic centimeter polymer • wherein T is the thickness of the populated area in mils; and wherein said wall has a transmission Hunter haze of up to about 1 percent per mil of the container wall. The present invention alsq includes a method for incorporating high levels of oxygen-scavenging particles into a film-forming polyester resin composition with low haze comprising the steps of: providing an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element, wherein the particles have a particle size distribution such that particles of less than about 25 microns in size do not exceed a concentration defined by the formula ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter;' adding said oxygen-scavenging particles to a polyester resin composition* during one -or more of the process steps of melt phase polymerization of the polyester; post polymerization and prior to pelletization; solid state polymerization of the polyester; and extrusion. The present invention also includes'a resin composition comprising a film-forming polyester; and particulates; Wherein the particulates have a particle size distribution such that particles of less than about 25 microns in size do not exceed a concentration defined by the formula '" ppm = 512.3 x d" ' wherein ppm is the approximate concentration of particles of less than about "25 microns in size in parts per million by weight, and d, is .the .apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter. ■ «. ■ ;■■ ;■- v-..;.. - ,;: ■ -■ Advantageously, the present invention ^overcomes the problems associated With the prior art-by providing a thermoplastic resin composition which contains an effective amount.of iron or other, oxygen scavenger and which has acceptable color and haze characteristics. The iron or other oxygen scavenger is present in an amount sufficient to effectively scravenge oxygen and Polymers containing repeating units of only one chemical/composition are homopolymers. Polymers with two or more chemically different repeat units in the same macromoleCule are termed copolymers. The diversity of the repeat : units depends on the number of different types of monomers present in the initial polymerization reaction. In the case of polyesters, copolymers include reacting one or more dipls with a diacid or multiple diacids, and are sometimes referred to as terpolymers. Suitable dicarboxylic acids include those comprising from about 6 to about 40 carbon atoms. Specific dicarboxylic acids include, but are not limited to, terephthalic acid, isophthalic acid, naphthalene 2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4!-dicarboxylic acid, 1,3-phenylenedioxydiacetic acid, 1,2-phenylenedioxydiacetic acid, 1,4-phenylenedioxydiacetic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and the like. Specific esters include, but are not limited to, phthalic esters and naphthalic diesters. These^ acids or esters may be reacted with an aliphatic diol having from about 2 to about 10 carbon atoms, a cycloaliphatic diol having from about 7 to about 14 carbon atoms, an aromatic diol having from about 6 to about 15 carbon atoms, or a glycol ether having from 4 to 10 carbon atoms. Suitable diols include, but are not limited to, 1,4-butenedipl, trimethylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, • resorcinol, and hydroquinone. Polyfunctional comonomers can also be used, typically in amounts of from about 0.1 to about 3 mole percent. Suitable comonomers include, but are not limited to, trimellitic anhydride, trimethyloprppane, pyromellitic ' dianhydride ,(PMDA), and pentaerythritol. Polyester-fpraiing polyacids or polyols can also be used. - ., ' -.;^ -, One preferred polyester is polyethylene terephthalate (PET) formed from the approximate 1:1 istoichiometric reaction pf terephtjialic acid, or its ester, with ethylene . glycol. ■ Another preferred polyester is . polyethylene naphthalate (PEN) formed from the approximate;.!;], to .J;1.6 stoichiometric ■,. ■ reaction of naphthalene dicarboxylic acid, or its ester, with ethylene glycol. Yet titanium tetrabutylate and titanium tetraisoprdpylate. The corresponding zirconium compounds may also be used. The polymer of this invention may also contain small amounts of phosphorous compounds, such as phosphates, and a catalyst such as a cobalt compound, that tends to impart a blue hue. The melt phase polymerization described above may be followed by a crystallization step, then a solid phase polymerization- (SSP) step to achieve the intrinsic viscosity necessary for bottle manufacture. The crystallization and polymerization can be performed in a tumbler dryer reaction in a batch-type system. 'Alternatively, the crystallization and polymerization can be accomplished in a continuous solid state process whereby the polymer flows from one vessel to another after its predetermined treatment in each vessel. The crystallization conditions preferably include a temperature of from about 100°C to about 150°C. The solid phase polymerization conditions preferably include a temperature of from about 200°C to about 232°C, and more preferably from about 215°C to about 232°C. The solid phase polymerization may by carried out for a time sufficient to raise the intrinsic viscosity to the desired level, which will depend upon the application. For a typical bottle application, the preferred intrinsic viscosity is from about. 0.65 to about 1.0 deciliter/gram, as determined by ASTM D-4603-86 at 30 °C in a 60/40 by weight mixture of phenol and tetrachloroethane. The time required to reach this viscosity may range from about 8 to about 21 hours. In one embodiment of the invention, film-forming polymer of the present invention may comprise recycled polyester, or materials derived from recycled polyester, such as polyester monomers, catalysts, and oligomers. The present invention provides a; container having at least one wall, wherein "the wall coinprises a populated area/ The populated area comprises a film-forming polymer and a population'of particles. There kfe technologies that can localize a population of particles into one area of a container wall. For example, where the contact surface of the film or wall is the surface adjacent to the packaged material, the oxygen scavenger could advantageously be localized in an area at the contact surface. Examples of these technologies preferably, the number of particles in the: populated area ^oes.not exceed a concentration of (3 x 107 particles & T) per cubic centimeter of polymer, wherein T is the thickness of the populated area in mils. Even more preferably, the number of particles in the populated area does not exceed a concentration of (1.5 x 107 particles ?■ T) per cubic centimeter of polymer, wherein T is the thickness of the populated area in mils, The population of particles comprises oxygen-scavenging particles, as well as any other components of the container, such as those discussed herein, that are present in the form of discrete particles. The oxygen-scavenging resin composition of the present invention further comprises oxygen-scavenging particles. Suitable oxygen-scavenging particles comprise at least one oxidizable material capable of reacting with molecular oxygen. Desirably, materials are selected that do not react with oxygen so quickly that handling of the materials is impracticable. Therefore, stable oxygen-scavenging materials that do not readily explode or burn upon contact with molecular oxygen are preferred. From a standpoint of food safety, materials of low toxicity are preferred, however with proper precautions, this is not a limitation. The particles should not adversely affect the organoleptic properties of the final product. Preferably, the oxygen-scavenging particles comprise an oxygen-scavenging element selected from calcium, magnesium, -scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, silver, tin, aluminum, antimony, germanium, silicon, lead, cadmium, rhodium, and combinations thereof. More preferably, the oxygen-scavenging particles comprise an oxygen-scavenging element selected from calcium, magnesium, titanium, vanadium, .manganese, iron, cobalt, nickel, copper, zinc, or tin. Even more preferably, ■ the oxygen-scavenging particles comprise iron. It will be understood that these oxygen-scavenging elements may be present £s mixtures, in compounds such as. oxides and salts, or otherwise combined with other elements, with the proviso that the oxygen-scavenging elements are capable of reacting with molecular oxygen. Metal alloys comprising at least one oxygen-scavenging element are also suitable. The oxygen-scavenging particles are present in an effective amount for adequate oxygen-Scavenging ability, if too few oxygen-scavenging particles are present, too much oxygen may be able to pass through the container wall without being scavenged. The amount required for adequate oxygen-scavenging ability depends on such factors as the application, the type of polymer used, the amount of gas barrier protection desired, the type of oxygen-scavenging particles, the particle size of the oxygen-scavenging particles, and moisture content of the packaged material. Preferably, the oxygen-scavenging container of the present invention comprises at least about 50 parts oxygen-scavenging particles per million parts by weight resin. More preferably, the container of the present invention comprises at least about 100 parts oxygen-scavenging particles per million parts by weight resin. Even more preferably, the container of the present invention comprises at least about 500 parts oxygen-scavenging particles per million parts by weight resin. Yet even more preferably, the container of the present invention comprises at least about 1000 parts, oxygen-scavenging particles per million parts by weight resin. It has been found that containers such as film or bottle articles comprising up to about 12,000 parts oxygen-scavenging particles per million parts by weight resin (1.2 weight percent) can have acceptable haze characteristics. For applications where haze is not an issue of concern, it will -be appreciated that the amount of oxygen-scavenging or other particles may be much higher. Further characterization of the population of particles that is necessary for practice of the present invention is provided hereinbelow. The composition of the present -invention may optionally further comprise one or more reaction-enhancing'agents known in the art to facilitate the oxygen-scavenging reaction. Examples of knowp. reaction-enhancing agents are discussed in U.S. Pat. Nos. 5,744,056 and 5885,481, hereby incorporated by reference in their entirety. Suitable agents are variously described as hydroscopic materials, electrolytic acidifying agents* non-electrolytic acidifying agents, metal haiides, metal sulfates, metal bisulfates, and salts. The reaction-enhancing agents may be added to the polymer melt, or during extrusion. transparency is the original intensity of the Incident radiation minus all light absorbed, scattered, or lost through .any other means. : -r Many polymers .are transparent, but polymers that are transparent to visible light may become opaque as the result of the presence of additives such ■as fillers, stabilizers, flame retardants, moisture, and, gases. The opacity results from light-scattering processes occurring within the material. The light scattering reduces the contrast between light, dark, and other colored parts of objects viewed through the material and produces a.milkiness or haze in the transmitted image. Haze is a measure of the amount of light deviating from the direction of transmittancy of the light by at least 2.5 degrees. : The color and brightness of a polyester article can be observed visually, and can also be quantitatively determined by a HunterLab ColorQuest Spectrometer. This instrument uses the 1976 CIE a, b, and L* designations of color and brightness. An a, coordinate defines a color axis wherein plus values are toward the red end of the color spectrum and minus values are toward the green end. The b coordinate defines a second color axis, wherein plus values are toward the yellow end of the spectrum and. minus values are toward the blue end. Higher L* values indicate enhanced brightness of the material. ' Generally, the acceptable haziness of an article, such as a bottle or . film, is determined visually. However, a HunterLab ColorQuest Spectrometer can quantitatively indicate the haze of an article or resin. This quantitative measurement is referred to herein as transmission Hunter haze. It is known in the art that a stretched film will often have more haze than its unstretched counterpart. Therefore, haze measurements were obtained on stretched and unstretched container, walls and through the bottle itself. . ., . ,..••■-,■..• ; ;i . -.;..,.. ... --, The container wall .of the present invention may comprise ■unstretched films or sheets. The manufacture: of films and sheets is lenown in the art, and any one of a number of suitable techniques can be used to prepare : the film. within the resin is expressed as the ftumber of,particles per volume of the . resin. ■■■■ .-■.,: > ,..-., .1 ■ ; . It will be understood that, within any particle population, the . particles are not all the same size, hut comprise a range of particle sizes. Furthermore,'the particles within the population may or may not have a •■ uniform, regular shape. The particle population, .or any portion of the population, may be described by an average particle s\|ze, as measured by any of the standard techniques known in the art. These techniques include measuring the equilibrium velocities of .particles settling through a liquid under "the influence of gravity, resistance pulse counters, light blockage counters, image analyzers, laser-diffraction spectroscopy, and photon correlation . spectroscopy. Statistical values commonly used to describe the particle size of a particle population include: (1) geometric mean size, which is the average • particle size calculated on a log basis; (2) arithmetic mean, which is the - average particle size calculated on a linear basis; (3) median size, which is the ; 50th percentile of the distribution;, and (4) mode size,, .which is the most prevalent particle size of the distribution. Further, the sample may be described by a particle size range, or as less than or equal to a given particle 1 size. These designations may be determined by sieving techniques, or other techniques known in the art. Thus, any given population of particles will have a particle size distribution, which is a description of the range of particle sizes and the amounts of particles of each; size. Techniques for particle size determination are further discussed by Paul Webb and Clyde Qrr in Analytical Methods in Fine Particle Technology, Micromeritics Instrument Corp. (1997), and by James P.M. Syvitski in Principles, Methods, and. Applications of Particle Size Analysis, Cambridge University Press (1991), both of winch are hereby -incorporated by reference in their entireties,.; mf. , -. , c Various parameters have been found to lae desirable: for the size of particles .within the particle population. For example, it wiU be appreciated that particles larger than the thickness of Jhe. container -wall may produce a rough surface, so that significant amounts of-sucli large particles are to be avoided. In general, it is preferred that the size of the particles fall within the particles of less than or equal to about 5 microns do not exceed about 500 parts per million by weight of the resin/More preferably, iron particles of less than or equal to about 5 microns do not exceed about 100 parts per million by weight of the resin. Accordingly, it is to be understood that the recitations throughout the specification and claims of "less than about 25 microns" are intended to include the smaller iron particle sizes of 20 microns, 10 microns, 5 microns, and less than 5 microns, depending upon the size that is preferred. Similarly, recitations of "do not exceed about 1250 parts per million" are intended to include the smaller amounts of 800 parts per million, 500 parts per million and 100 parts per million, depending upon the amount that is preferred. It will be appreciated that particles larger than the thickness of the bottles and other packaging materials made by using the high-iron thermoplastic resin composition may produce a rough surface, so that significant amounts of such large particles are to be avoided. More generally, the advantageous particle size distribution of the oxygen-scavenging particles is determined as a function of the apparent density of the particles. The density of a metal powder particle is not necessarily identical to the density of the material from which it is produced because of the internal porosity of the particle; Apparent density refers to the weight of a unit volume of loose powder, usually expressed in grams per cubic centimeter (g/cm3). The characteristics of a powder that determine its apparent density are discussed in Peter K Johnson, "Powder Metallurgy" in Kirk Othmer Encyclopedia of Chemical Technology, §§4.1, 4.2 (1995). Typical apparent density values for iron particles reported by Johnson range from about 0.97 to about 3.4 grams per cubic centimeter. When particles comprising iron or other materials are employed, the advantageous particles size distribution of the particles is determined by the following formulae. Preferably, the particle size distribution of the oxygen-scavenging particles is such that particles of less than or equal to about 25 microns do not exceed a concentration defined by the fonnula ppm = 512.3 ,x d ■■>: . Desirably* the particle size distribution of the oxygen-scavenging particles is such that particles of less than or equal to about 10 microns do not exceed a concentration defined by the formula ppm = 327.9 x d wherein ppm is the approximate concentration of particles of less than about 10 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 10 microns in size in grams per cubic centimeter. • More desirably, the particle size distribution -of ..the oxygen-scavenging particles is such that particles.of less than or equal to about 10 microns do not exceed a concentration defined by-the formula ppm = 204.9 x d wherein ppm is the approximate concentration of particles of less than about 10 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 10 microns in size in grams per cubic centimeter. Even more desirably, the particle size distribution of the oxygen-scavenging particles, is such that particles of less than or equal to about 10 microns do not exceed a concentration defined by the formula ppm = 41.0 x d wherein ppm is the approximate concentration of particles of less than about 10 microns in size in. parts per million by weight, and d is the apparent density , of the particles of less than about 10 microns in size in grams per cubic centimeter. Preferably, the particle size distribution of the oxygen-scavenging particles is such that particles of less than or equal to about 5 microns do not exceed a concentration defined by the formula -■. _ ppm = 204.9 X d wherein ppm is the approximate concentration pf particles of less than about 5 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 5 microns in size in grams per .cubic centimeter. populated area and at least one other area. The additional polymer may be a different polymer or the same polymer but without any scavenger present. The oxygen-scavenging resin having low haze, according to the present invention, can be cast into unstretched films or sheet of any thickness typically employed in the art of pblymer films. In a preferred embodiment, the film has a thickness of at least about 6.5 mils, and a transmission Hunter haze number of, preferably, less than about 10 percent, more preferably less than about 8 percent, and even more preferably less'than about 5 percent. While higher than the haze numbers for polyester samples comprising' no oxygeii-scavenging or other particles, these haze values are well within the range of values acceptable for many commercial applications. The oxygen-scavenging resin having low haze, according to the present invention, can be stretched into bottles wherein each bottle side-wall has a thickness of from about 9 to about 35 mils, preferably from about 11 to about 25 mils, and more preferably from about 14 to about 21 mils. In a preferred embodiment, each bottle side-wall has a thickness of from about 14 to about 21 mils, and the bottle has a Hunter haze number of, preferably, less than about 10 percent, more preferably less than about 8 percent, and even more preferably less than about 5 percent, at optimum blow window conditions. While higher than the haze numbers for polyester samples comprising no iron or other particles of oxygen-scavenging composition, these haze values are well within the range of values acceptable for many commercial applications. The maximum preferred concentrations of particles recited above were determined for unstretched films having a crystallinity of less than about 1 percent. In general, as the crystallinity of the pblymer resin increases, haze increases. >■■ It will therefore be understood that the maximum preferred concentration of particles will be lower in polymer compositions having higher crystallinity^ ;:a ■.•■-.,..•■- ■ .-.,„>-n„ ..-* ■ . "■'■ In order to demonstrate the practice of the present invention, the following examples have been prepared and tested as described, in the General The haze measurements were taken through the bottle sidewall, which is the thinned, stretched portioii, ^Becattse these measurements were taken on the whole bottle, the thickness actually contains two sidewalls. A HunterLab ColorQUEST Sphere Spectrophotometer System equipped with an IBM PS/2 Model 50Z computer, IBM Proprinter II dot matrix printer, assorted specimen holders, and green, gray and white calibration tiles, and light trap was used. The Hmiterkab Spectjocolorimeter integrating sphere sensor is a color and appearance measurement instrument. light from the lamp is diffused by the integrating sphere and passed either through (transmitted) or reflected (reflectance) off an object to a. lens. The lens collects the light and directs it to a diffraction grating that disperses it into its component wave lengths. The dispersed light is reflected onto a silicon diode array. Signals from the diodes pass through an amplifier to a converter and are manipulated to produce the data. Haze data is provided by the software. It is the calculated ratio of the diffuse light transmittance to the total light transmittance multiplied by 100 to yield a "Haze %" (0% being a transparent material, and 100% being an opaque material). Samples prepared for either transmittance or reflectance must be clean and free of any surface scratches or abrasions. The size of the sample must be consistent with the geometry of the sphere opening and in the case of transmittance, the sample size is limited by the compartment dimension. Each sample is tested in four different places, for example on the bottle sidewall or representative film area. A Panametrics Magna-Mike 8Q00 Hall Effect Thickness Gauge was employed to measure the bottle sidewall thickness. A small steel ball is placed on one side of the test material and a magnetic probe underneath. The distance between the b?ill and the probe is measured by means of the Hall effect sensor. More specifically, a Magna-Mike 8000 equipped with a DPU-411 thermal printer (type II), a remote foot switch, a target ball kit, and a Standard 801PR Probe was used. Two measurements were taken and averaged. The iron particle concentration, average iron particle size, and the haze values at a constant sample thickness of from about 11 to about 13 mils and optimum blow window conditions are summarized in Tables 1 and 2. Preparation of Examples Nos. 33-44 In order to investigate the Optimum concentration of particles of various sizes in uiistretched resin, films Were made by using a Haake mixer. 2500.0 grams of HiPERTUF 89010 qppolyester tesiii was Weighed into each pf several i-gallon cans and dried in a vacuum oven under full vacuum at about 100° C overnight. The vacuum was restored to atmospheric pressure with nitrogen. Appropriate amounts of carbonyl-type iron powder, manufactured by ISP Technologies was weighed under nitrogen into vials for the different concentrations desired. The nominal particle size range of the iron provided by the supplier was about 7 to about 9 microns. The geometric mean particle size based on volume for this iron powder was about 7.819 microns. The iron was added to the resin just prior to removing the hot resin from the oven, the vials were sealed, and the mixture was blended on a roller mill for about 5 minutes. f , The blended mixture was added to the feed hopper of a Haake Polylab extrusion system for film production. The resin was melted in the extruder and forced out of the die in the form of a flat sheet. The thin, unoriented, substantially amorphous film was fed through a 3-roll temperature-controlled polishing stack, quenched to minimize crystallinity and to give a final, polished surface. The cooled film was wound onto a core. The thickness of the films measured in mils, the percent transmission Hunter haze, and the percent haze per mil for typical film samples having a constant concentration of iron are shown in Table 4. The concentration of iron is about 0.9659 x 106 particles per cubic centimeter polymer for Examples 33 and 34, and about 2.8978 x 106 particles per cubic centimeter polymer for Examples 35-37. It can be seen that, while haze increases with increasing film thickness, the haze per mil of film thickness stays constant. In Examples 38-44, the thickness of t&e films was kept constant at about 11 mils, number of particles per cubic centimeter of polymer was varied. It can be seen that the haze per mil thickness increases with increasing particle concentration. than or equal to about 5 microns, haze values of less than 10% are obtained at iron levels up to about 500 ppm. When the population of particles is a constant parts by weight per million parts polymer, the number of particles per cubic centimeter of polymer decreases as the particle size increases, as shpwnin Table 3. The overall transmission Hunter haze increases as the thickness of the sample increases, as shown, in Table 4; however,the haze per mil of thickness stays relatively constant .; Haze yalues of .less than l.Q°/g per mi of a container wall are obtained at concentrations of particles of up to (6 x 107 particles + T) per cubic centimeter of polymer, wherein T is the thickness of the populated area in mils, as shown in Table 5.. As should now be understood, the present invention overcomes the problems associated with the prior art by providing a thermoplastic resin composition which contains an effective amount of oxygen-scavenging particles and which has acceptable color and haze characteristics. The resulting resin can be used to form transparent bottles, films, and other containers and packaging materials. These materials comprise oxygen-scavenging particles in an amount sufficient to effectively scavenge oxygen and provide longer shelf life for oxygen-sensitive materials. Furthermore, these materials have acceptable haze characteristics. While the best mode and preferred embodiment of the invention have been set forth in accordance with the Patent Statutes, the scope of this invention is not limited thereto, but rather .15 defined by the attached claims. Thus, the scope of the invention includes all modifications and variations that may fall within the scope of the claims. CLAIMS What is claimed is: 1. A resin composition comprising: a film-forming polyester; and an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such that particles of less than about 25 microns in size are present, but do not exceed a concentration defined by the formula ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter. 2. The resin composition of claim 1, wherein said polyester comprises linear polyesters or branched polyesters. 3. The resin composition of claim 1, wherein said polyester comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate. 4. The resin composition of claim 1, wherein said oxygen-scavenging element comprises calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc,. tin, aluminum, antimony, germanium, silicon, lead, cadmium, rhodium, or combinations thereof. The resin composition of claim 1, wherein said oxygen-scavenging element comprises iron. The resin composition of claim 1, wherein said effective amount of oxygen-scavenging particles is from about 50 to about 2500 parts per million by weight of the resin. The resin composition of claim 1, wherein said oxygen-scavenging particles have a particle size range of about 20 to about 70 microns. The resin composition of claim 1, wherein said particles of less than about 25 microns in size have an apparent density of from about 0.97 to about 2.44 grams per cubic centimeter. The resin composition of claim 1, wherein particles of less than about 20 microns in size have an apparent density of from about 0.97 to about 2.44 grams per cubic centimeter, and do not exceed a concentration of about 800 pans per million by weight of the resin. The resin composition of claim 1, wherein said oxygen-scavenging panicles are pre-treated with one or more reaction-enhancing agents. The resin_ composition of claim 1, wherein bottles produced from said resin have a Hunter haze value of about 10 % or less. A resin composition comprising: a film-forming polyester; and an effective amount of oxygen-scavenging iron particles, wherein the iron particles have a particle size distribution such that particles of less than about 25 microns in size are present, butjio not exceed about 1250 parts per million by weight of the resin. The resin composition of claim 12, wherein said polyester comprises linear polyesters or branched polyesters. The resin composition of claim 12, wherein said polyester comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate. The resin composition of claim 12, wherein said effective amount of iron particles is from about 50 to about 2500 parts per million by weight of the resin. The resin composition of claim 12, wherein said iron panicles have a particle size range of about 2Q to about 70 microns. The resin composition of claim 12, wherein particles of less than about 20 microns in size do not exceed about 800. pans per million by weight of the resin. The resin composition of claim 12, wherein said oxygen-scavenging panicles are pre-treated with one or more reaction-enhancing agents. The resin composition of claim 12, wherein bottles produced from said resin have a Hunter haze value of about 10 %. A resin composition comprising a film-forming* polyester and from about 50 to about 2500 pans by weight of oxygen-scavenging iron panicles per million pans by weight of the resin, wherein the concentration of iron •IGP.P.PC0079CIP-A particles of less than about 25 microns in size does not exceed about 1250 pans per million by weight of the resin. 21. The resin composition of claim 20, wherein said polyester comprises linear polyesters or branched polyesters. 22. The resin composition of claim 20, wherein said polyester comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate. 23. The resin composition of claim 20, wherein said iron particles have a particle size range of from about 20 to about 70 microns. 24. The resin composition of claim 20, wherein particles of less than about 20 microns in size do not exceed about 500 parts per million by weight of the resin. 25. The resin composition of claim 20, wherein said oxygen-scavenging particles are pre-treated with one or more re action-enhancing agents. 26. The resin composition of claim 20, wherein bottles produced from said resin have a Hunter haze value of about 10 % or less when stretched to a thickness of from about 11 to about 16 mils. 27. A polyester resin composition for use in forming transparent articles having low haze, the resin composition comprising from about 50 to about 2500 parts by weight of iron particles per million by weight of the resin, wherein said transparent articles have a Hunter haze value of about 10% or less. The resin composition of claim 27, wherein said polyester comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate,. polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate. The resin composition of claim 27, wherein said iron particles have, a particle size distribution such that particles of less than about 25 microns in size do not exceed a concentration defined by the formula ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter. An article formed from a resin composition comprising an effective amount of oxygen-scavenging particles, wherein the Hunter haze value of the article is about 10 % or less. The article of claim 30, wherein said article is a bottle. The article of claim 30, wherein said resin composition comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthcdate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate. The article of claim 30, wherein said Hunter haze value of said article is about 8 % or less. ■. A method for incorporating high levels of oxygen-scavenging particles into a film-forming polyester resin composition with low haze comprising the steps of: ( providing an effective amount of oxygen-scavenging particles; comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen, wherein the particles have a particle size distribution such that particles of less than about 25 microns in size are present, but do not exceed a concentration defined by the formula ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter; adding said oxygen-scavenging particles to a polyester resin composition during one or more of the process steps of melt phase polymerization of the polyester; post polymerization and prior to pelletization; solid state polymerization of the polyester; and extrusion. 5. The method of claim 34, wherein said step of adding oxygen-scavenging particles to a polyester resin composition produces a masterbatch of oxygen-scavenging resin; and wherein said method further comprises the step of adding said masterbatch to additional resin. 16. The method of claim 34, wherein said polyester resin comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate. . The method of claim 34, wherein said oxygen-scavenging particles comprise oxidizable forms of calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc, tin, aluminum, antimony, germanium, silicon, lead, cadmium/ rhodium, or combinations thereof. , The method of claim 34, wherein said oxygen-scavenging element comprises iron. The method of claim 35, wherein said oxygen-scavenging element comprises iron. The method of claim 34, wherein said effective amount of oxygen-scavenging panicles is from about 50 to about 2500 parts per million by weight of the resin. The method of claim 34, wherein said panicles of less than about 25 microns in size have an apparent density of from about 0.97 to about 2.44 grams per cubic centimeter. The method of claim 34, wherein panicles of less than about 20 microns in size have an apparent density of from about 0.97 to about 2.44 grams per cubic centimeter, and do not exceed a concentration of about 800 pans per million by weight of the resin. The method of claim 34, wherein said oxygen-scavenging panicles are pre-treated with one or more reaction-enhancing agents. The method of claim 34, wherein bottles produced from said resin have a Hunter haze value of about 10 % or less. 45. A resin composition comprising: a film-forming polyester; and particulates comprising oxygen-scavenging particles capable of reacting with molecular oxygen; wherein the particulates have a particle.' size distribution such that particles of less than about 25 microns in size are present, but do not exceed a concentration defined by the formula ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter. 46. A container having at least one wall, wherein the wall comprises a populated area, and wherein the populated area comprises: a film-forming polymer; and a population of particles comprising an effective amount of oxygen-scavenging particles, wherein the number of particles of said population does not exceed a concentration of (6 x 107 particles + T) per cubic centimeter of polymer wherein T is the thickness of the populated area in mils; and wherein said wall has a transmission Hunter haze of up to about 1 percent per mil of the container wall. 47. The container of claim 46, wherein said polymer comprises polyester. 48. The container of claim 47, wherein said polyester comprises linear polyester. 49. The container of claim 48, wherein said polyester comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate. m The container of claim 46, wherein the polyester is prepared from one or. more polyfunctional comonomers. The container of claim 50, wherein said polyfunctional comonomers are selected from the group consisting of pyromellitic dianhydride and pentaerythritol. The container of claim 46, wherein said effective amount is at least about 50 parts per million by weight oxygen-scavenging particles per million parts by weight polymer. The container of claim 46, wherein said oxygen-scavenging particles comprise at least one of calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc, tin, aluminum, antimony, germanium, silicon, lead, cadmium, rhodium, or combinations thereof. The container of claim 47, wherein said oxygen-scavenging panicles comprise at least one of calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc, tin, aluminum, antimony, germanium, silicon, lead, cadmium, rhodium, or combinations thereof. The container of claim 48; wherein said oxygen-scavenging particles comprise ar least one of calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc, tin, aluminum, antimony, germanium, silicon, lead, cadmium, rhodium, or combinations thereof. The container of claim 49, wherein said oxygen-scavenging particles comprise at least one of calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc, tin, aluminum, antimony, germanium, silicon, lead, cadmium,/ rhodium, or combinations thereof. The container of claim 46, wherein said oxygen-scavenging particles comprise iron. The container of claim 47, wherein said oxygen-scavenging particles comprise iron. The container of claim 48, wherein said oxygen-scavenging particles comprise iron. The container of claim 49, wherein said oxygen-scavenging particles comprise iron. The container of claim 46, wherein said oxygen-scavenging particles comprise iron, and wherein said oxygen-scavenging particles are present in an amount of from about 50 to about 12,000 parts per million by weight of the resin. The container of claim 46, wherein said polymer further comprises one or more components selected from the group consisting of impact modifiers, surface lubricants, denesting agents, stabilizers, crystallization aids, antioxidants, ultraviolet light absorbing agents, catalyst deactivators, colorants, nucleating agents, acetaldehyde reducing agents, reheat reducing agents, fillers, branching agents, blowing agents, and accelerants. The container of claim 46, wherein said population of particles turtiier comprises reaction-enhancing particles. The container of claim 63, wherein said reaction-enhancing particles comprise hydroscopic materials, electrolytic acidifying agents, non-; electrolytic acidifying agents, metal halides, metal sulfates, metal bisulfates, or mixtures thereof. The container of claim 46, wherein said oxygen-scavenging particles are pretreated with at least one reaction-enhancing agent. The container of claim 46, wherein said container is a stretched bottle having a sidewall thickness of from about 11 to about 25 mils and a Hunter haze value of about 10 % or less. The container of claim 47, wherein said container is a stretched bottle having a sidewall thickness of from about 11 to about 25 mils and a Hunter haze value of about. 10 % or less. The container of claim 48, wherein said container is a stretched bottle having a sidewall thickness of from about 11 to about 25 mils and a Hunter haze value of about 10 % or less. The container of claim 49, wherein said container is a stretched bottle having a sidewall thickness of from about 11 to about 25 mils and a Hunter haze value of about 10 % or less. The container of claim 46, wherein said populated area comprises a laminated layer of the wall of the container. The container of claim 46, wherein said populated area comprises a coextruded layer of the wall of the container. The container of claim 46, wherein said thickness of said populated area is equal to the thickness of the container wall. - The container of claim 46, wherein the thickness of said populated area is; less than the thickness of said container wall. The container of claim 46, wherein said container is a tray. A resin composition comprising: a film-forming polyester; and an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such that particles within the size range, of from about 25 to about 38 microns are present, and particles within the size range of from about 38 to about 45 microns are present, and wherein particles of less than about 25 microns in size do not exceed a concentration defined by the formula ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter. A resin composition comprising: a film-forming polyester; and an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such that particles within the size range of from about 38 to about 45 microns are present, and particles within the size range of from about 45 to about 75 microns are present, and wherein particles of less than about 25 microns in size do not exceed a concentration defined by the formula ppm - 512.3 x d . wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the; apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter, 77. A resin composition comprising: a film-forming polyester; and an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such that particles within the size range of from about 25 to about 38 microns are present, and particles within the size range of from about 38 to about 75 microns are present, and wherein particles of less than about 25 microns in size do not exceed a concentration defined by the formula ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter. 78. A resin composition comprising: a film-forming polyester; and an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such thar particles within the size range of from about 25 to about 45 microns are present, and particles within the size range of from about 45 to about 75 microns are present, and wherein particles of less than about 25 microns in size do not exceed a concentration defined by the formula ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in; grams per cubic centimeter. A resin composition substantially as herein above described and exemplified. A container having at least one wall substantially as herein above described and exemplified.

Full Text

OXYGEN-SCAVENGING RESIN COMPOSITIONS AND CONTAINERS HAVING LOW HAZE AND RELATED METHODS
BACKGROUND OF THE INVENTION
Thermoplastic resins such as polyethylene terephthalate (PET) are Commonly lised to manufacture packaging materials. PET processed under the right conditions produces high strength articles with excellent gas barrier properties. Foods, beverages, arid medicines can deteriorate or Spoil if exposed to oxygen. To improve shelf life and flavor retention of products such as foods, beverages, and medicines, therefore, the barrier protection provided by PET is often supplemented with additional layers of packaging material or with the addition of oxygen scavengers.
Adding a layer of gas barrier film is known as passive-barrier packaging. Ethylvinyl alcolhol (EVOH), Polyvinylidene dichldride (PVDC), and Nylon MXD6, are examples of films commonly used for this purpose due to their excellent oxygen barrier properties. Using distinct layers of differing materials is not preferred, however, because it adds cost to packaging construction and does not reduce the levels of oxygen already present in the package.
Adding oxygen scavengers to the PET resin is known as active-barrier packaging. This approach to protecting oxygen-sensitive products is tvvo-fold; the packaging prevents oxygen from reaching the product from the outside, arid also absorbs some of the oxygen present in the container and frorii within the polymer matrix. In some applications, small packets or sachets containing oxygen scavengers are added to the packaging container and he next to the food. Sachets are generally limited to solid foods, where the sachet
can be readily removed from the foodstuff arid hot accidentally ingested.
...... .. - ... .. \ ..,
Construction of the sachets and the cumbersome nature of their introduction
into the package result in increased costs.
One way to overcome the disadvantages of sachets is to incorporate
the scavenger direcdy into the wall of the food package. This can be done by
placing the scavenger throughout the scavenger wall or placing the scavenger

contents which migrates into the polymer and contacts the scavenging composition.
The use of scavenging powders in clear packages has previously been limited by aesthetics, particularly haze and color. High loadings of iron powder, on the order of 500 - 5000 parts per "million, are typically required to obtain sufficient oxygen absorption. Conventional wisdom and prior art teaches the practitioner to use the highest amount of scavenging surface area possible so that the efficiency and capacity is increased and the amount of iron added is minimized. In practice, this means a large number of small particles. Unfortunately, previous attempts at preparing resin compositions comprising high levels of small particles of iron for use in clear packages have resulted in packages with poor optical properties. This is particularly true vvhen the resin composition is stretched or oriented to any degree in forming the final article, such as in polyester bottles. Typically, bottles prepared from such resin compositions are translucent. Haze values for these bottles are generally high, and clarity is lacking.
Thus, there remains a heed for packaging materials having acceptable visual aspects and comprising oxygen scavenging resin compositions. This invention relates to an oxygen-scavenging resin composition having utility in packaging and other applications. More specifically, this invention relates to a film-forming, oxygen-scavenging polyester resin composition having low haze. The present invention also relates to a container having effective oxygen-scavenging functionality and low haze. The present invention further relates to a method for incorporating high levels of oxygen-scavenging particles into a film-forming polyester resin composition with low haze.
BRIEF SUMMARY OF THE INVENTION
, In general the present invention provides a resin composition comprising: a film-forming polyester; and an effective amount of oxygen-scavenging particles comprising at least qne oxygea-seav^nging element; wherein the particles have a particle size distribution such that particles of less

(6.0 x 107 particles * T) per cubic centimeter polymer • wherein T is the thickness of the populated area in mils; and wherein said wall has a transmission Hunter haze of up to about 1 percent per mil of the container wall.
The present invention alsq includes a method for incorporating high levels of oxygen-scavenging particles into a film-forming polyester resin composition with low haze comprising the steps of: providing an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element, wherein the particles have a particle size distribution such that particles of less than about 25 microns in size do not exceed a concentration defined by the formula
ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about
25 microns in size in parts per million by weight, and d is the apparent density
of the particles of less than about 25 microns in size in grams per cubic
centimeter;' adding said oxygen-scavenging particles to a polyester resin
composition* during one -or more of the process steps of melt phase
polymerization of the polyester; post polymerization and prior to pelletization;
solid state polymerization of the polyester; and extrusion.
The present invention also includes'a resin composition comprising a
film-forming polyester; and particulates; Wherein the particulates have a
particle size distribution such that particles of less than about 25 microns in
size do not exceed a concentration defined by the formula '"
ppm = 512.3 x d" ' wherein ppm is the approximate concentration of particles of less than about
"25 microns in size in parts per million by weight, and d, is .the .apparent density
of the particles of less than about 25 microns in size in grams per cubic
centimeter. ■ «. ■ ;*■■ ;■- v-..;.. - ,;:
■ -■ Advantageously, the present invention ^overcomes the problems
associated With the prior art-by providing a thermoplastic resin composition
which contains an effective amount.of iron or other, oxygen scavenger and
which has acceptable color and haze characteristics. The iron or other oxygen
scavenger is present in an amount sufficient to effectively scravenge oxygen and

Polymers containing repeating units of only one chemical/composition are homopolymers. Polymers with two or more chemically different repeat units in the same macromoleCule are termed copolymers. The diversity of the repeat : units depends on the number of different types of monomers present in the initial polymerization reaction. In the case of polyesters, copolymers include reacting one or more dipls with a diacid or multiple diacids, and are sometimes referred to as terpolymers.
Suitable dicarboxylic acids include those comprising from about 6 to about 40 carbon atoms. Specific dicarboxylic acids include, but are not limited to, terephthalic acid, isophthalic acid, naphthalene 2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4!-dicarboxylic acid, 1,3-phenylenedioxydiacetic acid, 1,2-phenylenedioxydiacetic acid, 1,4-phenylenedioxydiacetic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and the like. Specific esters include, but are not limited to, phthalic esters and naphthalic diesters.
These^ acids or esters may be reacted with an aliphatic diol having from about 2 to about 10 carbon atoms, a cycloaliphatic diol having from about 7 to about 14 carbon atoms, an aromatic diol having from about 6 to about 15 carbon atoms, or a glycol ether having from 4 to 10 carbon atoms. Suitable diols include, but are not limited to, 1,4-butenedipl, trimethylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, • resorcinol, and hydroquinone.
Polyfunctional comonomers can also be used, typically in amounts of
from about 0.1 to about 3 mole percent. Suitable comonomers include, but are
not limited to, trimellitic anhydride, trimethyloprppane, pyromellitic
' dianhydride ,(PMDA), and pentaerythritol. Polyester-fpraiing polyacids or
polyols can also be used. - ., *' -.;^ -,
One preferred polyester is polyethylene terephthalate (PET) formed
from the approximate 1:1 istoichiometric reaction pf terephtjialic acid, or its
ester, with ethylene . glycol. ■ Another preferred polyester is . polyethylene
naphthalate (PEN) formed from the approximate;.!;], to .J;1.6 stoichiometric
■,. ■ reaction of naphthalene dicarboxylic acid, or its ester, with ethylene glycol. Yet

titanium tetrabutylate and titanium tetraisoprdpylate. The corresponding zirconium compounds may also be used.
The polymer of this invention may also contain small amounts of phosphorous compounds, such as phosphates, and a catalyst such as a cobalt compound, that tends to impart a blue hue.
The melt phase polymerization described above may be followed by a crystallization step, then a solid phase polymerization- (SSP) step to achieve the intrinsic viscosity necessary for bottle manufacture. The crystallization and polymerization can be performed in a tumbler dryer reaction in a batch-type system. 'Alternatively, the crystallization and polymerization can be accomplished in a continuous solid state process whereby the polymer flows from one vessel to another after its predetermined treatment in each vessel.
The crystallization conditions preferably include a temperature of from about 100°C to about 150°C. The solid phase polymerization conditions preferably include a temperature of from about 200°C to about 232°C, and more preferably from about 215°C to about 232°C. The solid phase polymerization may by carried out for a time sufficient to raise the intrinsic viscosity to the desired level, which will depend upon the application. For a typical bottle application, the preferred intrinsic viscosity is from about. 0.65 to about 1.0 deciliter/gram, as determined by ASTM D-4603-86 at 30 °C in a 60/40 by weight mixture of phenol and tetrachloroethane. The time required to reach this viscosity may range from about 8 to about 21 hours.
In one embodiment of the invention, film-forming polymer of the present invention may comprise recycled polyester, or materials derived from recycled polyester, such as polyester monomers, catalysts, and oligomers.
The present invention provides a; container having at least one wall, wherein "the wall coinprises a populated area/ The populated area comprises a film-forming polymer and a population'of particles. There kfe technologies that can localize a population of particles into one area of a container wall. For example, where the contact surface of the film or wall is the surface adjacent to the packaged material, the oxygen scavenger could advantageously be localized in an area at the contact surface. Examples of these technologies

preferably, the number of particles in the: populated area ^oes.not exceed a concentration of (3 x 107 particles & T) per cubic centimeter of polymer, wherein T is the thickness of the populated area in mils. Even more preferably, the number of particles in the populated area does not exceed a concentration of (1.5 x 107 particles ?*■ T) per cubic centimeter of polymer, wherein T is the thickness of the populated area in mils,
The population of particles comprises oxygen-scavenging particles, as well as any other components of the container, such as those discussed herein, that are present in the form of discrete particles.
The oxygen-scavenging resin composition of the present invention further comprises oxygen-scavenging particles. Suitable oxygen-scavenging particles comprise at least one oxidizable material capable of reacting with molecular oxygen. Desirably, materials are selected that do not react with oxygen so quickly that handling of the materials is impracticable. Therefore, stable oxygen-scavenging materials that do not readily explode or burn upon contact with molecular oxygen are preferred. From a standpoint of food safety, materials of low toxicity are preferred, however with proper precautions, this is not a limitation. The particles should not adversely affect the organoleptic properties of the final product. Preferably, the oxygen-scavenging particles comprise an oxygen-scavenging element selected from calcium, magnesium, -scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, silver, tin, aluminum, antimony, germanium, silicon, lead, cadmium, rhodium, and combinations thereof. More preferably, the oxygen-scavenging particles comprise an oxygen-scavenging element selected from calcium, magnesium, titanium, vanadium, .manganese, iron, cobalt, nickel, copper, zinc, or tin. Even more preferably, ■ the oxygen-scavenging particles comprise iron. It will be understood that these oxygen-scavenging elements may be present £s mixtures, in compounds such as. oxides and salts, or otherwise combined with other elements, with the proviso that the oxygen-scavenging elements are capable of reacting with molecular oxygen. Metal alloys comprising at least one oxygen-scavenging element are also suitable.

The oxygen-scavenging particles are present in an effective amount for adequate oxygen-Scavenging ability, if too few oxygen-scavenging particles are present, too much oxygen may be able to pass through the container wall without being scavenged. The amount required for adequate oxygen-scavenging ability depends on such factors as the application, the type of polymer used, the amount of gas barrier protection desired, the type of oxygen-scavenging particles, the particle size of the oxygen-scavenging particles, and moisture content of the packaged material. Preferably, the oxygen-scavenging container of the present invention comprises at least about 50 parts oxygen-scavenging particles per million parts by weight resin. More preferably, the container of the present invention comprises at least about 100 parts oxygen-scavenging particles per million parts by weight resin. Even more preferably, the container of the present invention comprises at least about 500 parts oxygen-scavenging particles per million parts by weight resin. Yet even more preferably, the container of the present invention comprises at least about 1000 parts, oxygen-scavenging particles per million parts by weight resin.
It has been found that containers such as film or bottle articles comprising up to about 12,000 parts oxygen-scavenging particles per million parts by weight resin (1.2 weight percent) can have acceptable haze characteristics. For applications where haze is not an issue of concern, it will -be appreciated that the amount of oxygen-scavenging or other particles may be much higher. Further characterization of the population of particles that is necessary for practice of the present invention is provided hereinbelow.
The composition of the present -invention may optionally further comprise one or more reaction-enhancing'agents known in the art to facilitate the oxygen-scavenging reaction. Examples of knowp. reaction-enhancing agents are discussed in U.S. Pat. Nos. 5,744,056 and 5*885,481, hereby incorporated by reference in their entirety. Suitable agents are variously described as hydroscopic materials, electrolytic acidifying agents* non-electrolytic acidifying agents, metal haiides, metal sulfates, metal bisulfates, and salts. The reaction-enhancing agents may be added to the polymer melt, or during extrusion.

transparency is the original intensity of the Incident radiation minus all light absorbed, scattered, or lost through .any other means. : -r
Many polymers .are transparent, but polymers that are transparent to visible light may become opaque as the result of the presence of additives such ■as fillers, stabilizers, flame retardants, moisture, and, gases. The opacity results from light-scattering processes occurring within the material. The light scattering reduces the contrast between light, dark, and other colored parts of objects viewed through the material and produces a.milkiness or haze in the transmitted image. Haze is a measure of the amount of light deviating from the direction of transmittancy of the light by at least 2.5 degrees.
: The color and brightness of a polyester article can be observed visually, and can also be quantitatively determined by a HunterLab ColorQuest Spectrometer. This instrument uses the 1976 CIE a*, b*, and L* designations of color and brightness. An a*, coordinate defines a color axis wherein plus values are toward the red end of the color spectrum and minus values are toward the green end. The b* coordinate defines a second color axis, wherein plus values are toward the yellow end of the spectrum and. minus values are toward the blue end. Higher L* values indicate enhanced brightness of the material. '
Generally, the acceptable haziness of an article, such as a bottle or . film, is determined visually. However, a HunterLab ColorQuest Spectrometer can quantitatively indicate the haze of an article or resin. This quantitative measurement is referred to herein as transmission Hunter haze.
It is known in the art that a stretched film will often have more haze than its unstretched counterpart. Therefore, haze measurements were obtained on stretched and unstretched container, walls and through the bottle
itself. . ., . ,..••■-*,■..• ; ;i . -.;..,.. ... --,
The container wall .of the present invention may comprise ■unstretched films or sheets. The manufacture: of films and sheets is lenown in the art, and any one of a number of suitable techniques can be used to prepare : the film.

within the resin is expressed as the ftumber of,particles per volume of the
. resin. ■■■■ .-■.*,: > ,..-., .1 ■ ; .
It will be understood that, within any particle population, the
. particles are not all the same size, hut comprise a range of particle sizes. Furthermore,'the particles within the population may or may not have a
•■ uniform, regular shape. The particle population, .or any portion of the population, may be described by an average particle s|ze, as measured by any of the standard techniques known in the art. These techniques include measuring the equilibrium velocities of .particles settling through a liquid under
"the influence of gravity, resistance pulse counters, light blockage counters, image analyzers, laser-diffraction spectroscopy, and photon correlation
. spectroscopy. Statistical values commonly used to describe the particle size of a particle population include: (1) geometric mean size, which is the average
• particle size calculated on a log basis; (2) arithmetic mean, which is the - average particle size calculated on a linear basis; (3) median size, which is the
; 50th percentile of the distribution;, and (4) mode size,, .which is the most prevalent particle size of the distribution. Further, the sample may be described by a particle size range, or as less than or equal to a given particle 1 size. These designations may be determined by sieving techniques, or other techniques known in the art. Thus, any given population of particles will have a particle size distribution, which is a description of the range of particle sizes and the amounts of particles of each; size. Techniques for particle size determination are further discussed by Paul Webb and Clyde Qrr in Analytical Methods in Fine Particle Technology, Micromeritics Instrument Corp. (1997), and by James P.M. Syvitski in Principles, Methods, and. Applications of Particle Size Analysis, Cambridge University Press (1991), both of winch are hereby
-incorporated by reference in their entireties,.; mf. , -. ,
c Various parameters have been found to lae desirable: for the size of particles .within the particle population. For example, it wiU be appreciated that particles larger than the thickness of Jhe. container -wall may produce a rough surface, so that significant amounts of-sucli large particles are to be avoided. In general, it is preferred that the size of the particles fall within the

particles of less than or equal to about 5 microns do not exceed about 500 parts per million by weight of the resin/More preferably, iron particles of less than or equal to about 5 microns do not exceed about 100 parts per million by weight of the resin. Accordingly, it is to be understood that the recitations throughout the specification and claims of "less than about 25 microns" are intended to include the smaller iron particle sizes of 20 microns, 10 microns, 5 microns, and less than 5 microns, depending upon the size that is preferred. Similarly, recitations of "do not exceed about 1250 parts per million" are intended to include the smaller amounts of 800 parts per million, 500 parts per million and 100 parts per million, depending upon the amount that is preferred. It will be appreciated that particles larger than the thickness of the bottles and other packaging materials made by using the high-iron thermoplastic resin composition may produce a rough surface, so that significant amounts of such large particles are to be avoided.
More generally, the advantageous particle size distribution of the oxygen-scavenging particles is determined as a function of the apparent density of the particles. The density of a metal powder particle is not necessarily identical to the density of the material from which it is produced because of the internal porosity of the particle; Apparent density refers to the weight of a unit volume of loose powder, usually expressed in grams per cubic
centimeter (g/cm3). The characteristics of a powder that determine its apparent density are discussed in Peter K Johnson, "Powder Metallurgy" in Kirk Othmer Encyclopedia of Chemical Technology, §§4.1, 4.2 (1995). Typical apparent density values for iron particles reported by Johnson range from about 0.97 to about 3.4 grams per cubic centimeter. When particles comprising iron or other materials are employed, the advantageous particles size distribution of the particles is determined by the following formulae.
Preferably, the particle size distribution of the oxygen-scavenging particles is such that particles of less than or equal to about 25 microns do not exceed a concentration defined by the fonnula
ppm = 512.3 ,x d

■■>: . Desirably* the particle size distribution of the oxygen-scavenging particles is such that particles of less than or equal to about 10 microns do not exceed a concentration defined by the formula
ppm = 327.9 x d wherein ppm is the approximate concentration of particles of less than about
10 microns in size in parts per million by weight, and d is the apparent density
of the particles of less than about 10 microns in size in grams per cubic
centimeter. •
More desirably, the particle size distribution -of ..the oxygen-scavenging particles is such that particles.of less than or equal to about 10 microns do not exceed a concentration defined by-the formula
ppm = 204.9 x d wherein ppm is the approximate concentration of particles of less than about
10 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 10 microns in size in grams per cubic centimeter.
Even more desirably, the particle size distribution of the oxygen-scavenging particles, is such that particles of less than or equal to about 10 microns do not exceed a concentration defined by the formula
ppm = 41.0 x d wherein ppm is the approximate concentration of particles of less than about
10 microns in size in. parts per million by weight, and d is the apparent density
, of the particles of less than about 10 microns in size in grams per cubic
centimeter.
Preferably, the particle size distribution of the oxygen-scavenging
particles is such that particles of less than or equal to about 5 microns do not
exceed a concentration defined by the formula
-■. _ ppm = 204.9 X d
wherein ppm is the approximate concentration pf particles of less than about 5
microns in size in parts per million by weight, and d is the apparent density of
the particles of less than about 5 microns in size in grams per .cubic centimeter.

populated area and at least one other area. The additional polymer may be a different polymer or the same polymer but without any scavenger present.
The oxygen-scavenging resin having low haze, according to the present invention, can be cast into unstretched films or sheet of any thickness typically employed in the art of pblymer films.
In a preferred embodiment, the film has a thickness of at least about 6.5 mils, and a transmission Hunter haze number of, preferably, less than about 10 percent, more preferably less than about 8 percent, and even more preferably less'than about 5 percent. While higher than the haze numbers for polyester samples comprising' no oxygeii-scavenging or other particles, these haze values are well within the range of values acceptable for many commercial applications.
The oxygen-scavenging resin having low haze, according to the present invention, can be stretched into bottles wherein each bottle side-wall has a thickness of from about 9 to about 35 mils, preferably from about 11 to about 25 mils, and more preferably from about 14 to about 21 mils.
In a preferred embodiment, each bottle side-wall has a thickness of from about 14 to about 21 mils, and the bottle has a Hunter haze number of, preferably, less than about 10 percent, more preferably less than about 8 percent, and even more preferably less than about 5 percent, at optimum blow window conditions. While higher than the haze numbers for polyester samples comprising no iron or other particles of oxygen-scavenging composition, these haze values are well within the range of values acceptable for many commercial applications.
The maximum preferred concentrations of particles recited above
were determined for unstretched films having a crystallinity of less than about
1 percent. In general, as the crystallinity of the pblymer resin increases, haze
increases. >■■ It will therefore be understood that the maximum preferred
concentration of particles will be lower in polymer compositions having higher
crystallinity^ ;:a ■.•■-.,..•■- ■ .-.,„>-n„ ..-* ■ .
"■'■ In order to demonstrate the practice of the present invention, the following examples have been prepared and tested as described, in the General

The haze measurements were taken through the bottle sidewall, which is the thinned, stretched portioii, ^Becattse these measurements were taken on the whole bottle, the thickness actually contains two sidewalls. A HunterLab ColorQUEST Sphere Spectrophotometer System equipped with an IBM PS/2 Model 50Z computer, IBM Proprinter II dot matrix printer, assorted specimen holders, and green, gray and white calibration tiles, and light trap was used. The Hmiterkab Spectjocolorimeter integrating sphere sensor is a color and appearance measurement instrument. light from the lamp is diffused by the integrating sphere and passed either through (transmitted) or reflected (reflectance) off an object to a. lens. The lens collects the light and directs it to a diffraction grating that disperses it into its component wave lengths. The dispersed light is reflected onto a silicon diode array. Signals from the diodes pass through an amplifier to a converter and are manipulated to produce the data. Haze data is provided by the software. It is the calculated ratio of the diffuse light transmittance to the total light transmittance multiplied by 100 to yield a "Haze %" (0% being a transparent material, and 100% being an opaque material). Samples prepared for either transmittance or reflectance must be clean and free of any surface scratches or abrasions. The size of the sample must be consistent with the geometry of the sphere opening and in the case of transmittance, the sample size is limited by the compartment dimension. Each sample is tested in four different places, for example on the bottle sidewall or representative film area.
A Panametrics Magna-Mike 8Q00 Hall Effect Thickness Gauge was employed to measure the bottle sidewall thickness. A small steel ball is placed on one side of the test material and a magnetic probe underneath. The distance between the b?ill and the probe is measured by means of the Hall effect sensor. More specifically, a Magna-Mike 8000 equipped with a DPU-411 thermal printer (type II), a remote foot switch, a target ball kit, and a Standard 801PR Probe was used. Two measurements were taken and averaged.
The iron particle concentration, average iron particle size, and the haze values at a constant sample thickness of from about 11 to about 13 mils and optimum blow window conditions are summarized in Tables 1 and 2.

Preparation of Examples Nos. 33-44 In order to investigate the Optimum concentration of particles of various sizes in uiistretched resin, films Were made by using a Haake mixer. 2500.0 grams of HiPERTUF 89010 qppolyester tesiii was Weighed into each pf several i-gallon cans and dried in a vacuum oven under full vacuum at about 100° C overnight. The vacuum was restored to atmospheric pressure with
nitrogen. Appropriate amounts of carbonyl-type iron powder, manufactured
by ISP Technologies was weighed under nitrogen into vials for the different
concentrations desired. The nominal particle size range of the iron provided
by the supplier was about 7 to about 9 microns. The geometric mean particle
size based on volume for this iron powder was about 7.819 microns. The iron
was added to the resin just prior to removing the hot resin from the oven, the
vials were sealed, and the mixture was blended on a roller mill for about 5
minutes. f ,
The blended mixture was added to the feed hopper of a Haake Polylab extrusion system for film production. The resin was melted in the extruder and forced out of the die in the form of a flat sheet. The thin, unoriented, substantially amorphous film was fed through a 3-roll temperature-controlled polishing stack, quenched to minimize crystallinity and to give a final, polished surface. The cooled film was wound onto a core. The thickness of the films measured in mils, the percent transmission Hunter haze, and the percent haze per mil for typical film samples having a constant concentration of iron are shown in Table 4. The concentration of iron is about 0.9659 x 106 particles per cubic centimeter polymer for Examples 33 and 34, and about 2.8978 x 106 particles per cubic centimeter polymer for Examples 35-37. It can be seen that, while haze increases with increasing film thickness, the haze per mil of film thickness stays constant.
In Examples 38-44, the thickness of t&e films was kept constant at about 11 mils, number of particles per cubic centimeter of polymer was varied. It can be seen that the haze per mil thickness increases with increasing particle concentration.

than or equal to about 5 microns, haze values of less than 10% are obtained at iron levels up to about 500 ppm.
When the population of particles is a constant parts by weight per million parts polymer, the number of particles per cubic centimeter of polymer decreases as the particle size increases, as shpwnin Table 3. The overall transmission Hunter haze increases as the thickness of the sample increases, as shown, in Table 4; however,the haze per mil of thickness stays relatively constant .; Haze yalues of .less than l.Q°/g per mi of a container wall are obtained at concentrations of particles of up to (6 x 107 particles + T) per cubic centimeter of polymer, wherein T is the thickness of the populated area in mils, as shown in Table 5..
As should now be understood, the present invention overcomes the problems associated with the prior art by providing a thermoplastic resin composition which contains an effective amount of oxygen-scavenging particles and which has acceptable color and haze characteristics. The resulting resin can be used to form transparent bottles, films, and other containers and packaging materials. These materials comprise oxygen-scavenging particles in an amount sufficient to effectively scavenge oxygen and provide longer shelf life for oxygen-sensitive materials. Furthermore, these materials have acceptable haze characteristics.
While the best mode and preferred embodiment of the invention have been set forth in accordance with the Patent Statutes, the scope of this invention is not limited thereto, but rather .15 defined by the attached claims. Thus, the scope of the invention includes all modifications and variations that may fall within the scope of the claims.

CLAIMS
What is claimed is:
1. A resin composition comprising:
a film-forming polyester; and
an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such that particles of less than about 25 microns in size are present, but do not exceed a concentration defined by the formula
ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter.
2. The resin composition of claim 1, wherein said polyester comprises linear polyesters or branched polyesters.
3. The resin composition of claim 1, wherein said polyester comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate.
4. The resin composition of claim 1, wherein said oxygen-scavenging element comprises calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc,. tin, aluminum, antimony, germanium, silicon, lead, cadmium, rhodium, or combinations thereof.

The resin composition of claim 1, wherein said oxygen-scavenging element comprises iron.
The resin composition of claim 1, wherein said effective amount of oxygen-scavenging particles is from about 50 to about 2500 parts per million by weight of the resin.
The resin composition of claim 1, wherein said oxygen-scavenging particles have a particle size range of about 20 to about 70 microns.
The resin composition of claim 1, wherein said particles of less than about 25 microns in size have an apparent density of from about 0.97 to about 2.44 grams per cubic centimeter.
The resin composition of claim 1, wherein particles of less than about 20 microns in size have an apparent density of from about 0.97 to about 2.44 grams per cubic centimeter, and do not exceed a concentration of about 800 pans per million by weight of the resin.
The resin composition of claim 1, wherein said oxygen-scavenging panicles are pre-treated with one or more reaction-enhancing agents.
The resin_ composition of claim 1, wherein bottles produced from said resin have a Hunter haze value of about 10 % or less.
A resin composition comprising:
a film-forming polyester; and
an effective amount of oxygen-scavenging iron particles, wherein the iron particles have a particle size distribution such that particles of less than about 25 microns in size are present, butjio not exceed about 1250 parts per million by weight of the resin.

The resin composition of claim 12, wherein said polyester comprises linear polyesters or branched polyesters.
The resin composition of claim 12, wherein said polyester comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate.
The resin composition of claim 12, wherein said effective amount of iron particles is from about 50 to about 2500 parts per million by weight of the resin.
The resin composition of claim 12, wherein said iron panicles have a particle size range of about 2Q to about 70 microns.
The resin composition of claim 12, wherein particles of less than about 20 microns in size do not exceed about 800. pans per million by weight of the resin.
The resin composition of claim 12, wherein said oxygen-scavenging panicles are pre-treated with one or more reaction-enhancing agents.
The resin composition of claim 12, wherein bottles produced from said resin have a Hunter haze value of about 10 %.
A resin composition comprising a film-forming* polyester and from about 50 to about 2500 pans by weight of oxygen-scavenging iron panicles per million pans by weight of the resin, wherein the concentration of iron

•IGP.P.PC0079CIP-A
particles of less than about 25 microns in size does not exceed about 1250 pans per million by weight of the resin.
21. The resin composition of claim 20, wherein said polyester comprises linear polyesters or branched polyesters.
22. The resin composition of claim 20, wherein said polyester comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate.
23. The resin composition of claim 20, wherein said iron particles have a particle size range of from about 20 to about 70 microns.
24. The resin composition of claim 20, wherein particles of less than about 20 microns in size do not exceed about 500 parts per million by weight of the resin.
25. The resin composition of claim 20, wherein said oxygen-scavenging particles are pre-treated with one or more re action-enhancing agents.
26. The resin composition of claim 20, wherein bottles produced from said resin have a Hunter haze value of about 10 % or less when stretched to a thickness of from about 11 to about 16 mils.
27. A polyester resin composition for use in forming transparent articles having low haze, the resin composition comprising from about 50 to about 2500 parts by weight of iron particles per million by weight of the resin, wherein said transparent articles have a Hunter haze value of about 10% or less.

The resin composition of claim 27, wherein said polyester comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate,. polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate.
The resin composition of claim 27, wherein said iron particles have, a particle size distribution such that particles of less than about 25 microns in size do not exceed a concentration defined by the formula
ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter.
An article formed from a resin composition comprising an effective amount of oxygen-scavenging particles, wherein the Hunter haze value of the article is about 10 % or less.
The article of claim 30, wherein said article is a bottle.
The article of claim 30, wherein said resin composition comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthcdate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate.
The article of claim 30, wherein said Hunter haze value of said article is about 8 % or less.

■. A method for incorporating high levels of oxygen-scavenging particles
into a film-forming polyester resin composition with low haze comprising
the steps of: (
providing an effective amount of oxygen-scavenging particles; comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen, wherein the particles have a particle size distribution such that particles of less than about 25 microns in size are present, but do not exceed a concentration defined by the formula
ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter;
adding said oxygen-scavenging particles to a polyester resin composition during one or more of the process steps of
melt phase polymerization of the polyester;
post polymerization and prior to pelletization;
solid state polymerization of the polyester; and
extrusion.
5. The method of claim 34, wherein said step of adding oxygen-scavenging particles to a polyester resin composition produces a masterbatch of oxygen-scavenging resin; and wherein said method further comprises the
step of adding said masterbatch to additional resin.
16. The method of claim 34, wherein said polyester resin comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene terephthalate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate.

. The method of claim 34, wherein said oxygen-scavenging particles comprise oxidizable forms of calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc, tin, aluminum, antimony, germanium, silicon, lead, cadmium/ rhodium, or combinations thereof.
, The method of claim 34, wherein said oxygen-scavenging element comprises iron.
The method of claim 35, wherein said oxygen-scavenging element comprises iron.
The method of claim 34, wherein said effective amount of oxygen-scavenging panicles is from about 50 to about 2500 parts per million by weight of the resin.
The method of claim 34, wherein said panicles of less than about 25 microns in size have an apparent density of from about 0.97 to about 2.44 grams per cubic centimeter.
The method of claim 34, wherein panicles of less than about 20 microns in size have an apparent density of from about 0.97 to about 2.44 grams per cubic centimeter, and do not exceed a concentration of about 800 pans per million by weight of the resin.
The method of claim 34, wherein said oxygen-scavenging panicles are pre-treated with one or more reaction-enhancing agents.
The method of claim 34, wherein bottles produced from said resin have a Hunter haze value of about 10 % or less.

45. A resin composition comprising:
a film-forming polyester; and
particulates comprising oxygen-scavenging particles capable of reacting with molecular oxygen; wherein the particulates have a particle.' size distribution such that particles of less than about 25 microns in size are present, but do not exceed a concentration defined by the formula
ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter.
46. A container having at least one wall, wherein the wall comprises a
populated area, and wherein the populated area comprises:
a film-forming polymer; and
a population of particles comprising an effective amount of oxygen-scavenging particles, wherein the number of particles of said population does not exceed a concentration of
(6 x 107 particles + T) per cubic centimeter of polymer wherein T is the thickness of the populated area in mils; and wherein said wall has a transmission Hunter haze of up to about 1 percent per mil of the container wall.
47. The container of claim 46, wherein said polymer comprises polyester.
48. The container of claim 47, wherein said polyester comprises linear polyester.
49. The container of claim 48, wherein said polyester comprises polyethylene terephthalate, copolymers of polyethylene terephthalate, polyethylene naphthalate, copolymers of polyethylene naphthalate, polybutylene

terephthalate, copolymers of polybutylene terephthalate, polytrimethylene terephthalate, or copolymers of polytrimethylene terephthalate. m
The container of claim 46, wherein the polyester is prepared from one or. more polyfunctional comonomers.
The container of claim 50, wherein said polyfunctional comonomers are selected from the group consisting of pyromellitic dianhydride and pentaerythritol.
The container of claim 46, wherein said effective amount is at least about 50 parts per million by weight oxygen-scavenging particles per million parts by weight polymer.
The container of claim 46, wherein said oxygen-scavenging particles comprise at least one of calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc, tin, aluminum, antimony, germanium, silicon, lead, cadmium, rhodium, or combinations thereof.
The container of claim 47, wherein said oxygen-scavenging panicles comprise at least one of calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc, tin, aluminum, antimony, germanium, silicon, lead, cadmium, rhodium, or combinations thereof.
The container of claim 48; wherein said oxygen-scavenging particles comprise ar least one of calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc, tin, aluminum, antimony, germanium, silicon, lead, cadmium, rhodium, or combinations thereof.

The container of claim 49, wherein said oxygen-scavenging particles comprise at least one of calcium, magnesium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, silver, zinc, tin, aluminum, antimony, germanium, silicon, lead, cadmium,/ rhodium, or combinations thereof.
The container of claim 46, wherein said oxygen-scavenging particles comprise iron.
The container of claim 47, wherein said oxygen-scavenging particles comprise iron.
The container of claim 48, wherein said oxygen-scavenging particles comprise iron.
The container of claim 49, wherein said oxygen-scavenging particles comprise iron.
The container of claim 46, wherein said oxygen-scavenging particles comprise iron, and wherein said oxygen-scavenging particles are present in an amount of from about 50 to about 12,000 parts per million by weight of the resin.
The container of claim 46, wherein said polymer further comprises one or more components selected from the group consisting of impact modifiers, surface lubricants, denesting agents, stabilizers, crystallization aids, antioxidants, ultraviolet light absorbing agents, catalyst deactivators, colorants, nucleating agents, acetaldehyde reducing agents, reheat reducing agents, fillers, branching agents, blowing agents, and accelerants.

The container of claim 46, wherein said population of particles turtiier comprises reaction-enhancing particles.
The container of claim 63, wherein said reaction-enhancing particles comprise hydroscopic materials, electrolytic acidifying agents, non-; electrolytic acidifying agents, metal halides, metal sulfates, metal bisulfates, or mixtures thereof.
The container of claim 46, wherein said oxygen-scavenging particles are pretreated with at least one reaction-enhancing agent.
The container of claim 46, wherein said container is a stretched bottle having a sidewall thickness of from about 11 to about 25 mils and a Hunter haze value of about 10 % or less.
The container of claim 47, wherein said container is a stretched bottle having a sidewall thickness of from about 11 to about 25 mils and a Hunter haze value of about. 10 % or less.
The container of claim 48, wherein said container is a stretched bottle having a sidewall thickness of from about 11 to about 25 mils and a Hunter haze value of about 10 % or less.
The container of claim 49, wherein said container is a stretched bottle having a sidewall thickness of from about 11 to about 25 mils and a Hunter haze value of about 10 % or less.
The container of claim 46, wherein said populated area comprises a laminated layer of the wall of the container.
The container of claim 46, wherein said populated area comprises a coextruded layer of the wall of the container.

The container of claim 46, wherein said thickness of said populated area is equal to the thickness of the container wall. -
The container of claim 46, wherein the thickness of said populated area is; less than the thickness of said container wall.
The container of claim 46, wherein said container is a tray.
A resin composition comprising:
a film-forming polyester; and
an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such that particles within the size range, of from about 25 to about 38 microns are present, and particles within the size range of from about 38 to about 45 microns are present, and wherein particles of less than about 25 microns in size do not exceed a concentration defined by the formula
ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter.
A resin composition comprising:
a film-forming polyester; and
an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such that particles within the size range of from about 38 to about 45 microns are present, and particles within the size range of from about 45 to about 75

microns are present, and wherein particles of less than about 25 microns in size do not exceed a concentration defined by the formula
ppm - 512.3 x d . wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the; apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter,
77. A resin composition comprising:
a film-forming polyester; and
an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such that particles within the size range of from about 25 to about 38 microns are present, and particles within the size range of from about 38 to about 75 microns are present, and wherein particles of less than about 25 microns in size do not exceed a concentration defined by the formula
ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in grams per cubic centimeter.
78. A resin composition comprising:
a film-forming polyester; and
an effective amount of oxygen-scavenging particles comprising at least one oxygen-scavenging element capable of reacting with molecular oxygen; wherein the particles have a particle size distribution such thar particles within the size range of from about 25 to about 45 microns are present, and particles within the size range of from about 45 to about 75 microns are present, and wherein particles of less than about 25 microns in size do not exceed a concentration defined by the formula

ppm = 512.3 x d wherein ppm is the approximate concentration of particles of less than about 25 microns in size in parts per million by weight, and d is the apparent density of the particles of less than about 25 microns in size in; grams per cubic centimeter.

A resin composition substantially as herein above described and
exemplified.
A container having at least one wall substantially as herein above
described and exemplified.

Documents:

0395-chenp-2004 abstract-duplicate.pdf

0395-chenp-2004 claims-duplicate.pdf

0395-chenp-2004 descripition(completed)-duplicate.pdf

395-chenp-2004-claims.pdf

395-chenp-2004-correspondnece-others.pdf

395-chenp-2004-correspondnece-po.pdf

395-chenp-2004-description(complete).pdf

395-chenp-2004-form 1.pdf

395-chenp-2004-form 18.pdf

395-chenp-2004-form 3.pdf

395-chenp-2004-form 5.pdf

395-chenp-2004-pct.pdf

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Patent Number

229921

Indian Patent Application Number

395/CHENP/2004

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

24-Feb-2009

Date of Filing

26-Feb-2004

Name of Patentee

M & G POLIMERI ITALIA S.p.A

Applicant Address

VIA MOROLENSE KM. 10, I-03010 PATRICA,

Inventors:

#	Inventor's Name	Inventor's Address
1	TUNG, DEBORAH	1038 BEECHWOOD DRIVE, TALLMADGE, OH 44278,
2	SISSON, EDWIN	2845 WOODHAVEN DRIVE, MEDINA, OH 44256,
3	LECKONBY, ROY	12195 YUMA CIRCLE, UNIONTOWN, OH 44685,

PCT International Classification Number

C08J 3/22

PCT International Application Number

PCT/US02/23824

PCT International Filing date

2002-07-25

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	09/916,671	2001-07-26	U.S.A.
2	10/195,385	2002-07-16	U.S.A.