Title of Invention

A HOMOGENEOUS POLYMERIC COMPOSITION

Abstract

A homogeneous polymeric composition suitable for manufacture of films having heat shrinkage greater than 70% comprising, a crystallized CoPET having an intrinsic viscosity of 0.8 dl/gm to 0.9 dl/gm to the extent of about 80% to 40% by mass of the total resin composition; a Polytrimethylene Terephthalate (PTT) having an intrinsic viscosity of 0.85 dl/gm to 0.95 dl/gm to the extent of about 20% to 60% by mass of the total composition; optionally a diol to the extent of about 5% to 20% by mass of the total resin composition; and optionally at least one additive selected from a group of additives consisting of a polycondensation catalyst, a coloring agent, a heat stabilizer and a cleat fast reheat additive.

Full Text

FORM - 2 THE PATENT ACT, 1970 (39 of 1970) & THE PATENT RULES, 2003 PROVISIONAL SPECIFICATION (See section 10 and Rule 13) POLYESTER RESIN FOR HIGH HEAT SHRINKAGE FILM FUTURA POLYESTERS LIMITED An Indian Company of Paragon Condominium, 3rd Floor, Pandurang Budhkar Marg, Mumbai-400 013, Maharashtra, India. THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION Field of the invention The present invention relates to polyester resins. Particularly, this invention relates heat shrinkage films and resins suitable for the making of such films. Prior art Conventional high heat shrinkage polyesters are formed from polyvinyl chloride and polystyrene which has low shrinkage properties, chemical and heat resistance. Moreover PVC heat shrinkage films are disfavored since they emit toxic pollutants when they are incinerated. Further, in use of heat-shrinkable vinyl chloride resinous film as shrinkable labels on PET containers, the labels and the containers are required to be separated from each other in recycling of the containers. On the other hand polystyrene films undergo shrinkage on long term storage. Other frequently used heat shrinkage polyesters includes glycol-modified polyethylene terephthalate glycol (PETG). Though PETG has relatively low glass transition temperature and a relatively high shrinkage upon exposure to heat, PETG is more difficult to process, since it tends to warp under adverse molding conditions. PETG is relatively expensive and has low melt strength, low heat deflection temperature, a tendency to absorb moisture, and relatively high specific gravity. A polymer consisting primarily of poly(ethylene terephthalate) with additional monomeric units selected from a diethylene glycol, propane-1,3-diol; butane-1,4-diol; polytetramethylene glycol; polyethylene glycol; polypropylene glycol and the like, substituted for the glycol moiety in the preparation of the copolymer and/or azelaic; isophthahc, bibenzoic, 1,4- or 2,6-naphthalene dicarboxylic, adipic, sebacic, decane-l,10-dicarboxylic acid, and the like, substituted for part of the acid moiety in the preparation of the copolymer is disclosed in U.S. Pat. No. 4,020,141. This patent discloses films having shrinkage of 31-47% in the machine or transverse direction after specific heat treatment. Shrinkable copolyester films disclosed in U.S. Pat. No. 5,070,180 uses aliphatic dicarboxylic acids like oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and 1,10-decanedicarboxylic acid or aromatic dicarboxylic acids like phthalic acid, isophthahc acid, naphthalenedicarboxylic acid and diphenyl ether dicarboxylic acid with a shrinkage of 30-65% at 100 deg C. Japanese Pat. No. 5,305,667 reports a heat shrinkage film comprising terephthalic acid, isophthahc acid, ethylene glycol and a propane diol derivative. U.S. Pat No. 5,340,624 uses cycloaliphatic acids such as 1,2- cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4- cyclohexanedicarboxylic acid and their cis/trans isomer mixtures for shrinkable co-polyester film with a shrinkage of 30-70% at 90 deg C. US Pat. No. 6,342,281 discloses a polyester film comprising of terephthalic acid and isophthahc acid as dicarboxylic acid components and ethylene glycol, dimer diol, and polytetramethylene glycol with shrinkage of more than 30%. US Pat No. 20020045055 discloses a polyester film with both outer layers and intermediate layer made from TPA mixed with IPA or adipic acid and EG mixed with butanediol, but the layers have different composition of these compounds. The degree of shrinkage is 50-60% after treatment in hot water at 80 deg C. Japanese Pat. No. 63139725 discloses a polyester composition constituting a film consists of copolymerized polyester containing terephthalic acid, isophthalic acid as a dicarboxylic acid component, ethylene glycol and 1,4-cyclohexanedimethanol as a diol component. The film has over 40% or more heat shrinkage. Japanese Pat No. 2005015801 discloses a heat shrinkable polyester film excellent in crystallinity and shrinkage of 2-3% in Transverse Direction (TD) and 50-60% in Machine Direction (MD) by melt-extruding neopentyl glycol as diol component, to increase the shrinkage factor, with PET - PIT. Other diol components include diethylene glycol, hexane diol, pentane diol, 2-methyl-l,2-propane diol etc. Korean Pat No. 7,018,689 discusses about a heat-shrinkable polyester film with base film comprising polyethylene terephthalate, polytrimethylene terephthalate and 2,2-dimethyl-(l,3-propylene)terephthalate and a coat layer of inorganic lubricants, formed on one or both sides of the polyester base film. The degree of shrinkage is 60-72%. Japanese Pat No. 7,001,651 discloses a polyethylene terephthalate (PET) which may be blended with copolyester from terephthalic acid, as the dicarboxyilc acid component, ethylene glycol, neopentyl glycol, and 1,4-cyclohexane dimethanol, as the polyhydric alcohol components; polybutylene terephthalate (PBT) may be blended with copolyester from terephthalic acid, as the dicarboxylic acid component, ethylene glycol, neopentyl glycol, and 1,4-cyclohexane dimethanol, as the polyhydric alcohol components for preparing a polyester film of not less then 20% shrinkage. US Pat No. 7,008,698 discloses a polyester resin polyethylene terephthalate modified with 5-50 mol% of 2-methyl-l,3-propane diol, as shrink enhancing agents, which is added in polymerization stage. The film has more than 50%o heat shrinkage at 80 deg C. Japanese Pat No. 2001288618 discloses a blended polymer of polyethylene terephthalate-based polyester with a polyethylene naphthalate for heat shrinkable fiber with more than 30%) heat shrinkage at 150 deg C. Korean Pat No. 8,501,235 discloses a high-shrinkage PET yarn with a shrinkage of 8-50% prepared from linear PET by spraying an organic solvent such as dimethyl formamide, benzyl alcohol, or dioxane. US Pat No. 5,070,185 discloses a yarn comprising poly(ethylene terephthalate) filaments formed with a boiling water shrinkage after drawing is at least 40%. Objects of the invention The object of the present invention is to provide polyester resin for film with heat shrinkage above 70% at 90 deg C. An object of the invention is to produce a polyester resin to which aliphatic diols or their esters are added in the esterification reaction and therefore do not need any further processing with the objective of incorporation of the property of heat shrinkage. It is an object of this invention to provide a polyester resin for shrink film applications, with excellent shrinkage properties and which in use as a shrink film is substantially free from wrinkles, and uneven shrinkage. Statement of invention The polyester resin of this invention comprises Polyethylene terephthalate (PET), Isophthalic acid (IPA), Polytrimethylene terephthalate (PTT) and 2-methyl-l,3-propanediol (MP diol). Particularly, this invention envisages a resin comprising polyethylene terephthalate (PET), Isophthalic acid (IPA), Polytrimethylene terephthalate (PTT) and 2-methyl-l,3-g a propanediol (MP diol) for makinhigh heat shrinkage film and a method for preparation of such a resin. Detailed Description of the invention It is discloses in this invention that the use of the aliphatic 2-methyl-l,3-propane diol in combination with co-polymer of PET/IPA - PTT imparts superior shrink properties to the film when compared films in the prior art. Though the use of MP diol for heat shrink film is known, its combination with CoPET-PTT is not known or suggested in literature or I application.. In general, Propane diol is found to accelerate crystallization and not as a shrink enhancing agent. However, when this diol is substituted with a methyl group and incorporated in the polymer chain, it is found to increase the shrinkage of the film. In order to incorporate MP diol in the polymer backbone, this invention suggests adding it at the esterification stage. The intrinsic viscosity (I.V.) of CoPET (copolymer of PET/IPA) and PTT used in the present invention is important. Typically, the PET should have an IV of 0.8-0.9 dL/g and PTT with 0.85-0.95 dL/g. If the IV is low, the processibility into shrink film will be difficult, the number of oligomers will be large and the resulting chip will be too weak. Moreover a high IV is maintained to suppress crystallization. The polyester composition used in the present invention contains dimethyl terephthalate or terephthalic acid as a dicarboxylic acid component, and at least one component selected from the group consisting of isophthalic acid, napthalenedicarboxylic acid, sebacic acid, adipic acid, diphenyldicarboxylic acid, 5-/-butyl isophtalic acid, 2,2,6,6-tetramethyldiphenyl-4,4'-dicarboxylic acid, l,l,3-trimethyl-3-phenylindan-4,5-dicarboxylic acid, 5-sodium sulfoisophthalic acid, trimellitic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, pimeric acid, azelaic acid, pyromellitic acid, 1,4-cyclohexane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid and an ester compound thereof. The diol component can be one or more components selected from diethylene glycol, triethylene glycol, hexanediol, pentanediol, diols of 2,2-(4- oxyphenol)propane derivatives, xylene glycol, butanediol, 1,3- cyclohexanedimethanol, 2,2-bis-(4-hydroxyphenyl)propane, bis(4- hydroxyphenyl)sulfone, polytetramethylene glycol, polyethylene glycol, and 2-methyl-l,3-propanediol. The main acid component is terephthalic acid, along with this IPA of about 5-40 mol% is mixed. The MP diol used in this invention is inexpensive when compared to available propane diols. Though the MP diol is singly substituted i.e., less branched when compared to other diols it imparts high shrink properties to the film and fiber. The MP diol is preferably added during the esterification reaction to incorporate the diols in the backbone of the polymer chain. According to this invention, high shrink properties are obtained even with low concentrations, say about 2-30 mol%, of MP diol. PET-PTT is prepared by polymerization following conventional procedure. CoPET can be produced from esterification of PTA, MP diol, EG and IPA. PTT of higher IV is taken and various compositions of CoPET - PTT, say 60:40, 70:30 and 80:20 ratios are prepared by physical blending. The polyester resin is then dried in a hopper, paddle or vacuum dryer at 100-180 deg C and extruded into a film. Any existing method can be used for this extrusion. The resulting film is then stretched at a ratio of 4:1 or higher in machine direction to form a stretched film. Shrinkage of the film made from the resin of this invention in boiling water is defined as shrinkage percentage decrease in length of material when exposed to elevated temperatures for a fixed period of time and under tension. Shrinkage is measured by treating a sample, 100 mm in length and 100 mm in width at 90 °C hot water for 10 seconds. The present invention is described in detail with an example: Terephthalic acid and ethylene glycol are taken in a molar ratio of 1:1.5 in esterification vessel. To this 12% of IPA and 6% of MP diol are added. The coloring agent, Co is added in the form of cobalt acetate (10 ppm as Co). The temperature of esterifier is increased from 240 to 270 °C for a period of 120 minutes. The prepolymer is then transferred to the polyreactor. The polymerization takes place in the presence of poly-catalyst, Antimony trioxide 120 ppm (as Sb) and Germanium dioxide 30 ppm (as Ge). Before commencing polymerization, Triethyl phosphonoacetate (TEPA, 60 ppm as P) and orthophosphoric acid (OPA, 10 ppm as P) and clear fast reheat additive (CFRH), oxides of Tungsten (15 ppm, as W) are added. The temperature is increased to 270 to 290 °C and pressure reduced to around 5 mbar for a period of 90 minutes. The amorphous polymer melt is extruded under nitrogen pressure and collected as pellets. The amorphous PET is upgraded to higher IV by solid state polymerization. The amorphous PET is dedusted, heated and crystallized inside a multi-zone fluid bed heat precrystallizer at 140 °C. The crystallized chips are then fed to the crystallizer, where crystallization is completed under process conditions optimized to the behavior of the feed polymer. Crystallization is performed in a nitrogen environment; the temperature is increased to 190 °C and maintained at this temperature till the desired IV is reached. CoPET and PTT in various compositions, say 60:40, 70:30 and 80:20 ratios are blended physically. The blended polymer is melted and extruded and solidified on a chill casting roll. The cast film has a thickness of 120 m. This film was drawn in machine direction in the ratio of 4:1 to form a stretched film of 30 m. Table-I Summarizes the important characteristics of the CoPET - PTT blend resin Description IV dL/g L*CIE a* CIE b*CIE COOHmeq/kg Tm1 °C CoPET PTT 80 20 0.87 82.7 -1.3 -1.8 15 225 70 30 0.88 81.8 -1.3 -1.1 15 226 60 40 0.88 80.9 -1.46 -0.4 14 227 Note: Tm1 is melting point determined in the 1st heating cycle of DSC measurement. Table-II A typical example of a film sample Descri ption IV dL/g Haze% L* CIE a* CIE b* CIE Tg °C Tm1 °C Teh °C CoPET PTT 70 30 0.77 3.9 96 0 0.4 63.1 220.2 155.9 Table-Ill Summarizes the shrinkage of the CoPET - PTT (30 m. thickness, 90 °C / 10 sec in water) Shrinkage test CoPET:PTT 80:20 70:30 60:40 MD 73 72 58 TD -2 -2 -4 While considerable emphasis has been placed herein on the steps and reactant chemical compounds of the preferred embodiments , it will be appreciated that many permutations and combinations of the process steps and the composition can be made and that many changes can be made in the preferred scheme without departing from the principles of the invention. These and other changes in the preferred process steps as well as other steps of the process of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Documents:

2304-MUM-2007-ABSTRACT(18-11-2008).pdf

2304-MUM-2007-CLAIMS(18-11-2008).pdf

2304-MUM-2007-CLAIMS(AMENDED)-(3-7-2012).pdf

2304-MUM-2007-CLAIMS(MARKED COPY)-(3-7-2012).pdf

2304-MUM-2007-CORRESPONDENCE(16-4-2009).pdf

2304-MUM-2007-CORRESPONDENCE(18-11-2008).pdf

2304-mum-2007-correspondence-received.pdf

2304-mum-2007-description (provisional).pdf

2304-MUM-2007-DESCRIPTION(COMPLETE)-(18-11-2008).pdf

2304-MUM-2007-FORM 18(16-4-2009).pdf

2304-mum-2007-form 2(18-11-2008).pdf

2304-MUM-2007-FORM 2(TITLE PAGE)-(18-11-2008).pdf

2304-mum-2007-form 2(title page)-(22-11-2007).pdf

2304-MUM-2007-FORM 5(18-11-2008).pdf

2304-mum-2007-form-1.pdf

2304-mum-2007-form-2.doc

2304-mum-2007-form-2.pdf

2304-mum-2007-form-26.pdf

2304-mum-2007-form-3.pdf

2304-MUM-2007-REPLY TO EXAMINATION REPORT(3-7-2012).pdf