Title of Invention	A PROCESS FOR RELEASING CONTAMINANTS FROM A POLYESTER SUBSTRATE
Abstract	This invention relates to a process for releasing contaminants from a polyester substrate comprising: combining materials containing contaminated polyester with an alkaline composition to form a slurry; and mixing said slurry in a high energy mixer operating at a Froude number greater than about 4.2, wherein said high energy mixer substantially coats said materials with said alkaline composition and imparts sufficient energy to said materials so as to saponify the outer surface of said polyester and cause. said contaminants to be released from said polyester into said slurry.

Title of Invention

A PROCESS FOR RELEASING CONTAMINANTS FROM A POLYESTER SUBSTRATE

Abstract

This invention relates to a process for releasing contaminants from a polyester substrate comprising: combining materials containing contaminated polyester with an alkaline composition to form a slurry; and mixing said slurry in a high energy mixer operating at a Froude number greater than about 4.2, wherein said high energy mixer substantially coats said materials with said alkaline composition and imparts sufficient energy to said materials so as to saponify the outer surface of said polyester and cause. said contaminants to be released from said polyester into said slurry.

Full Text	PROCESS FOR SEPARATING POLYESTER FROM OTHER MATERIALS CroasJReference to Related Application This application claims priority to an earlier filed U.S. provisional patent app-ication Serial Number 60/299273 filed June 19. 2001 entitled, "Process for Separating Polyester from other Materials." Background of the invention Polyesters are polymeric materials mado from the eslerification of polvb&sic organic acids with polyhydric acids. Perhaps the most commonly made and used polyester is polyethylene terephthalate (PET),, which can be manufactured by reacting xerephthalic acid with ethylene glycol. Polyesters are currently being used in ircreasing amounts in various applications. For instance, polyesters are commonly used to Tiake all types of containers such as beverage and fooc containers, photographic films, X-ray films, magnetic recording tapes, electrical insulation, surgical aids such as syr.Viatic arteries, fabrics and other textile products, and other numerous items Because polyesters can be remelted arid reformed, many efforts are jnderv/ay to recycle as much polyester as possible after use. Before pollsters can be recycled, however, it is necessary to separate the post-consumer polyesters from other products and materials that may be found mixrci with or coupled with the polyester. Unfortunately, many problems have betin encountered In attempting to separate polyester from other waste mater .sis. In particular, many prior art processes ar« not capable of efficiently or fiijo-iomicaliy recovering polyester when a significant amount of impurities and ccntaminants are present Most prior art processes for separating polyesters from other materials have been limited to floatation separation techniques and mechanical recovery processes. In floatation separation techniques; polyesters are separated from other materials based on density differences. For instance, materials containing polyester can be combined with water, in which polyester is known (o sink. The less dense materials, which float rn water, can thus be easily separated from the submerged polyester. This procedure is relatively simple and very effective in separating polyesters from specific low density impurities, Floatation separation techniques, however, cannot, be used if the polyester is found in combination with materials that sink in water or that have densities comparable to th3t of polyester. For instance, post consumer polyester is typically mixed with polyvinyl chloride (PVC) and alumin jm, which are not water buoyant. In fact, PVC has a density that is very similar to the density of PET and is often misidentified as PET. Both aluminum and PVC must be separated from polyester before it car be reused. In particular, if PET and PVC are remelted together, hydrochloric acid gases an? produced which destroy the properties of the resulting plastic material. In the past, in order to separate PET from PVC using a floatation separation technique in a specific gravity bath, others have attempted to modify the surface of the PVC so that the PVC will float in an aerated aqueous medium. For instance, in U.S. Patent No. 5,234,110 to Kobler and U.S Patent No. 5,120,763 tc Sisson various processes for separating PET from PVC flakes are disclosed. !n these processes, the surface of the PVC flakes is treated in a manner so lhat the surface of the PVC is more Hkely to adher-3 to air buDbles when placed in an aqueous medium. In order for these processes to be efficient, however, the PVC flakes must have a high surface area to volume ratio. Consequently, the above processes are deficient in separating PVC c-.ips from PET whan the PVC chips have a large interior voluin®. Besides failing to separate polyesters from heavier-thai-water impurities, floatatiDn separation techniques also fail to remove coatings that are commonly adhered to polyester. For example, poiyester containers are cor-monly coated with vapor barrier coatings, saran coatings, and/or inks. Mechanical recovery processes as usee herein are washing processes use a to strip specific binder and adhesive layers off polyester films without substantial reaction occurring between the polyester and the wash solution. For example, U, S. Patent Nos. 5,286,463 and 5,366,993 both to Schwartz, Jr., both of which are incorporated herein by reference thereto, disclose a composition and process for removing adhesives, particularly polyvinylidene halide and polyvinyl haiide based resins, from polyester films, such as photographic films. In one embodiment, the polyester films are mixed with a reducing sugar and a base to remove the adhesive polymeric resin from the film. An acid is then added to precipitate the resin, which can then be separated from the polyester film. U.S. Patent No. 4,602,046 to BuseretaL discloses a method for the recovery of polyester from scrap materia! such as photographic film having a polyester base and at Ieas>t one layer of macromoiecular organic polymer. Specifically, scrap material is cut or chopped into small individual pieces or flakes and treated in a caustic alkaline solution at a solids level of at least 25% ':)y voiume and under conditions of high shear. The organic polymer coating material is removed from the polyester flakes. The polyester flakes are then separated from the polymer coating materia! by filtration or centrifugation, rinsed in water, and dried. The recovered polyester flakes can be used as a feed stock for making films, bottles or other polyester articles. A method and apparatus for recovering silver and plastic from used film is aSso disclcsed in U.S. Patent Mo. 4,392,889 to Grout. In this method, the used film is firs? passed through a bath preferably comprising a hot caustic solution for precipitating silver layered on the film. The film then passes through a second bath cf hot caustic until an adhesive sheet disposed on the film has been dissolved. Typically, the adhesive sheet is made of polyvinylidene chloride, which adheres the silver \o the film. After a second caustic bath, the film is dried and available for use. Other processes for recovering polyester from photographic films are disclosed in U.S. Patent No. 3,928,253 to Thornton otaL U.S. Patent No. 3,652.466 to Hitteletal.. U S. Patent No. 3,647,422 to Wainor. and U.S. Patent No. 3,873,314 to Woo et_aL - As shown above, mechanical recovery processes have generally been limited.to use with photographic films. In recycling the photographic films, silver is also recovered making the processes economically viable. Mechanical recovery processes, although veiy successful at removing the enul& successful in removing other types of coatings from polyesters. For instance, most el these processes are not capable of efficiently removing some of the vapor barrier coatings and inks that are applied to polyesters. Other contaminants that are generally not removable from polyesters using rioatation separation techniques and mechanical recovery processes as de$.crbecl above are entrained organic and inorganic compounds. These contaminants include, for instance, gasoline, kerosene, motor oil, toluene, pefilicides and other compounds that are absorbed by polyesters when placed in contact therewith. If the entrained organic and inorganic compounds are not substantially removed from the polyester materials during recycling, the recycled polyesters cannot be used as food containers or as beverage containers. Because of the above noted deficiencies in prior art processes, large amounts of recyclable polyesters are being scrapped and loaded into landfills or are being incinerated. Unfortunately, not only is the polyester not being re jsed, but the polyester materials are creating a waste management and disposal problem. Recently, the focus of recovering polyester from the waste stream has changed from mechanical washing processes to chemically converting the polyester into usable chemical components. For instance, in U.S. Patents No. 5,358.987, 6,147,129, and 6,197.838, all to Schwartz, Jr., which are incorporated herein by reference thereto, processes for recycling polyesters in which a portion of the polyesters are reduced to their original chemical reactants are disclosed. The processes include the steps of combining the polyester materials with an alkaline composition to form a mixture. The mixture is heated to a temperature sufficient to convert the surface of the polyester to an alkaline salt of a polybasic organic acid and a polyol. The above described patents represent great advancements in the ait The process of the present invention is directed to further improvements in processes for recycling polyesters. Summary of the Invention In general, the process of the present invention is directed to a process for separating a poiyester substrate from various contaminants and impurities. For example, the process of the present invention can be used to release var-ous contaminants from a polyester substrate to which the contaminants have been coupled, i.e. either adhered or entrained contaminants. Additionally, the process of the present invention can facilitate the separation of polyester from other contaminants which can be mixed with poiyester in the wE.ste stream; aluminum and polyvinyl chloride, for example. Tne process of the present invention generally includes mixing materials containing polyester with an alkaline composition to form a slurry. The slurry can Lhen be mixed in a high energy mixer which can not only substantially and evenly coat the materials with the alkaline composition, but can also impart sufficient energy so as to promote reaction between the mater als and the alkaline composition which can enable separation of the poiyester from various contaminants and impurities. For example, the slurry can b$ mixed in a high energy plow mixer. In one embodiment, the mixer can operate at a Froude number greater than about 4.2 to promote the reaction. Specncaliy, the mixer can operate at a Froude number greater than about 6.6. h one embodiment, the'mixer can operate at a Froude lumber greater than about 9.5. In general, the alkaline composition can be a metal hydroxide solution. For example, the metal hydroxide can be sodium hydroxide, calcium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, or mixtures thereof. In one embodiment, the alkaline composition can be formed of only sodium hydroxide and water. For example, the alkaline composition can be sodium hydroxide and water in a 1:1 ratio. The alkaline composition can be combined with the polyester materials in an amount so as to saponify as little of the polyester as possible and yet st il promote separation of the polyester from any contaminants or impurities For example, the alkaline composition can be combined with the polyester materials in an amount of less than about 10% by weight of the polyester materials. Specifically, the alkaline composition can be combined with the polyester materials in a stoichiometric amount sufficient to react with less than about 20% of the polyester. More specifically, the alkaline composition can be combined with the polyester materials in a stoichiometric amount sufficient to react with less than about 10% of the polyester. The reaction process can substantially exhaust the metal hydroxide in th& mixer. For example, trie metal hydroxide remaining in the slurry aftei the mixing1 and reaction process can generally be less than about 1% of the weigh;; of the slurry. Specifically, the metal hydroxide remaining in the slurry aftsr the mixing and reaction process can generally be less than about 0.5% of Tie weight of the slurry. More specifically, the metal hydroxide remaining in the slurry after the mixing and reaction process can generally be iess than about 0.1 % of tie weight of the slurry, If desired, the slurry can be heated after the reaction in the mixer is substantially complete. For example, the slurry can be heated to a first temperature, such as, for example, a temperature of between about 12GUC and anout 170°C. to dry the slurry and produce a dry product and then heated to a second temperature, such as, for example a temperature of between about 200°C and about 240°C, which can further degrade the contaninants and make them easier to separate from the polyester substrate. in one embodiment, the polyester containing materials can include contaninants which are coupled to the polyester substrate, such as contaminants which are entrained in the polyester or contaminants which are adhur esd to the surface of 'tie polyester. In this embodiment, the alkaline composition can react with the materials during mixing and cause saponification of a portion of the polyester which can release the contaminants from the surface of the polyester substrate, Alternatively, the polyester containing materials can include impurities or cor-:arr inants which are mixed with the polyester, though not necessarily coupled to the polyester, such as polyvinyl chloride or aluminum materials, for exanple. In this embodiment, the alkaline composition can react with the contaminant and cause them to be altered into a form which is more easily separable from the polyester. For example, polyvinyl chloride can be dechlorinated by the alkaline composition in which form it can be easily separated from the polyester substrate. Detailed Description of Preferred Embodiments The present invention is generally directed to a process for recovering and separating polyesters from various contaminants and impurities. For instance, through the process of the present invention, various contaminants can be released from a polyester substrate such as various coalings inducing vapor barrier coatings, inks, and saran coatings as well as other contaminants which are entrained within the outer surface o- the polyester substrate, such as various volatile organic and inorganic contaminants. During the process, the polyester can be partially saponified but largely remain in polymer form and the contaminants car be physically released from the polyester substrate. The process is aiso directed to the separation and recovery of polyester when mixed with other types of impurities such as polyvinyl chloride and aluminum, for example. During the process, the impurities can be converted into a form which is more easily separable from the polyester substrate. As used herein, a poiyester is definec as an esterification or reaction product between a poiybasic organic acid and a poiyol. It is believed that any known polyester or copolyester may be used in the process of the present invention. The process of the present invention is particularly directed to a class of polyesters referred to herein as poiyol polyterephtha ates, in which terephthalic acid serves as the poiybasic organic acid. As used herein, a poiybasic organic acid refers to any organic acid havircj two or mere carboxyf groups (-COOH). Most polyesters are derived from eibasic acids or, in other words, from dicarboxylic acids. Poiybasic acids can have a linear or a cyclic conformation. Examples of linear poiybasic acids that can be used to make polyesters include the aliphatic dicarboxylic acids. In particular the aliphatic dicarboxylic acids having up to ten carbon atoms in their chains can be used. These acids include adipic acid, glutaric acid, succinic acid, malonic acid, oxalic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, and fumaric acid. Cyclic pclybasic organic acids, on the other hand, include the carbocycllc tricarboxylic acids. These acids are known as phthalic acid, isophthalic acid, and terephthalic acid, in particular, terephthalic acid is used to make polyethylene terephthalate, which is'perhaps the most commercially available polyester. As described above, a polybasic organic acid is combined with a polyol to produce a polyester. Polyols are compounds that contain at least two hyciroxyl groups. Many polyesters are synthesized using a polyol that conta'ns two hydroxy! groups, which are referred to as diols. Diois are normally prepared from an alkene by the net addition of two hydroxy groups to the double carbon bond in a method known as hydroxylation. Polyols are commonly referred to as glycols and polyhydric alcohols, Examples of polyols us For exemplary purposes, the following table contains a nonexhaustive iist of commercially available polyesters that may be recovered and recycled according to the present invention. For each polyester, the corresponding polybasic organic add and polyol are provided, POLYESTER POLYBASIC DIOL ORGANIC ACID Polyethylene Terephthalic Acid Ethylene Glycol Terephthalate Polyb Jtylene Terephthalic Acid But/lene Glycol Terephthalate PETG Copolyester Terephthalic Acid Cydohexane- dimethanol and Ethylene Glycol PE3TG Copolyester Terephthalic Acid Cydohexane- dimethanol and Butylene Glycol >olycyclohexane- Terephthalic Acid Cyciohexane- linethanol dirnethanoi ferepnthalate EN Polyester Napthalene tricarboxylic Ethylene Glycol Acid In general, the process of the present invention includes first combining materials containing polyester with a selected amount of an alkaline solution to form a slurry in a mixer. The mixer chosen is one which can not only provide substantially complete and even coating of the polyester mater als by the alkaline solution, but also can impart sufficient energy to cause a portion of the polyester to saponify, or, in other words, to hydrolyze. Durng saponification, various coatings that may be adhered to the polyester and/or other contaminants which may Ixs entrained within the surface of the polyester can be releasee from the polyester, "f he energy provided from the mixir can also promote reaction between the alkaline solution and other impur ties whicn can be mixed in with the polyester in the SIUT/, such as polyvinyl chloride or aluminum, for example, such that the impurities can be converted to another form, one which is more easily separable from the pclyester substrate. After the reaction within the mixer, the slurry can then be heated, usualiy in a two-step heating process. The process of the present invention can run continuously or can be set up as a batch system. Practically any materia! containing a polyester can be processed by the present invention including but not limited to, for Hnole: beverage and food containers, photographic and X-ray films, -ezording tapes, insulation materials, textile fibers and other products. Preferably, the polyester materials are recovered from the solid waste stream, th JS alleviating many environmental concerns and disposal problems. The present invention is particularly directed io recycling food containers and beverage containers made from PET. Through the process of the present invention, polyesters can be separated, recovered and reused from post consumer waste, even when the polyesters are found mixed with polyvinyl chloride or aluminum, adhered to various coatings, or entrained with various organic and inorganic compounds. Such materials are currently being disposed of in landfills or are being incinerated after use due to a lack of an economical process that will recover the polyester. Prior to be;ng contacted with the alxaline composition, the materials containing the poiyester can be, if desired, cnopped or ground into a particular size. Sizing of the materials is done solely for the purpose of facilitating handling. Generally speaking, the larger the size of the materials and the less surface area to volume ratio, the less saponification of the polyester will occur later in the process. Consequently, smaller dimensions should be avoided anc iifK! size of the materials should be left as large as practicable. However, it should be understood that all different sizes and shapes of material may be used within the process of the present invention and no one size or shape is required. Also prior to being combined with Ihe alkaline composition, the materials containing the polyester can be in:meseu in water or some other fluid in order to separate tha'less dense or lighter materials fron the heavier materials containing the polyester. More particularly, it is known that polyester sinks in water while paper products and other polymers, such as polyoietlns, are water buoyant. Thus, the lighter materials can be easily separatsd from the heavier materials when contacted with a flud. Subjecting the inaisrials to a sink/float separation step prior to contacting :he materials wltt1. the alkaline composition not only can reduce the quantity of materials being processed but also can dean the surface of the materials prior to further processing. After being sized anc! subjected to a sink/float separation, if desired, the polyester containing materials can be combined and mixed with an alkaline composition to form a slurry, or mixture. Preferably, an alkaline solution can be combined with the materials so as to coat the material surfe.ee. In some applications, the material surface can resist uniform coating due i.c surface tension interaction. In this situation, the alkaline solution has a tendency to "bead up" on the material surface. The process of the present invention, however, as described below, can overcome this problem. In accordance with the present invention, it has been discovered that an improved mixing process can be employed which can not only coat the polyester materials with the alkaline solution more completely and evenly, but in addition can impart sufficient energy to the mixture to cause saponification of the outside surface of the polyester to occur within the mixer. For example, mixefis such as those described in U.S. Patent Nos, 4,320,979 to Lucke and 4,189.242 to jjjke, which are herein incorporated in their entirety by reference thereb, may be employed for coating of the polyester materials and saponification of at least a portion of the polyester with an alkaline solution. The alkaline compound selected for mixing with the materials is preferably sodijrn hydroxde, known commonly as caustic soda. Other metai hydroxides and alkaiines lowever, can be used. Such compounds include calcium hydroxide, magnesium hydroxide, potassium hydroxide, lithium hydroxide or mixtures theeof. The alkaline compound can be added to the polyester materials in solution, if desired. ro; instance, in one embodiment, a metal hydroxide, such as sodium hydroxide, can be mixed with water in about a 1:1 ratio to form the alkaline composition. The amount of the aikaiine composition added to the materials containing the polyester will depend upon :he type and amount of impurities and contaminants present within the materials. Generally, the aikaiine composition should be added only in an amount sufficient to separate the impurities from the polyester, so as to minimize the saponification of the polyester. In most applications, the alkaline composition is added to the mater als in a stoichiometric amount sufficient to react with up to about 50% of the polyester. For example, the alkaline composition can be added in an amount sufficient to react with less than about 20% of the poyester. Specifically, the alkaline composition can be added in an amount sufficient to react with about less than about 15% of in© polyester. More specifically, the alkaline composition can be added in an amount sufficient to react with less than sbout 10% of the polyester. One of the benefits of the present invention is the ability of the mixer to coat the polyester materia! without the need of a wetting agent. In the past, a surfactant or wetting agent v/as often employed in order to facilitate the mixing of-:he alkaline composition with the polyester materials. Due to the improved mixing of the present invention, the use of a wetting agent is no longer necr&sary In one embodiment of the present invention a reactor in the form of a mixer can be utilized. In one particular embodiment, a plow mixer can be used. For example, a plow mixer such as those available from the LSdige Company, the Littieford Day Company, or other known companies can be usod. In one particular embodiment, a mixer such as the Littieford Day KM-42C0 mixer can be utilized. This particular mixer is available from the Llttlefcrd Day Company of Florence, Kentucky Besides a plow mixer, however, it should be understood that various other high energy mixers can be tsed. Similarly, it should be understood that the process can be run as either a continuous or a batch process. An amount of ground or chopped polyester material car be added to the mixer after any desired pretreatment processes have been performed, such as, for example, the floatation separation processes as previously discussed. An alkaline solution can then be added to the mixer with the polyester material. For example, a alkaline solution of 50% NaOH and 50% water can be added to the mixer in an amount up to about 20% by weight of the material containing the polyester, and particularly in an amount less than about 10% by'weight of the material containing the polyester. The mixer can be operated at a rate which can impart sufficient energy to the mixture so as to substantially eveniy coat the polyester material with the alkaline mixture and promote saponification of the outside surface of the polyester material such that most of the alkaline reactant is exhausted in the mixer. In general, mixers can normally be operated at a preset rotational speed specific to the particular device and adapted to the particular process. In order to maintain equivalent energy input when using different mixers, the dimensionless value Fr (Froude number) Is introduced, instead of the rotational speed. Fr is a dirnensionless number which describes the ratio of inertial forces to gravitational forces. The Froude number can be described by :h« following formula: Fr := V2/(gL) wherein Fr is the Froude number, V is the velocity, g is the gravitational acceleration, and L is a characteristic length. Ir. one embodiment of the present invention, the mixer can be operateu ai a Froude number greater than about 4,2, particularly greater than 6.6, and rroro particularly greater that about 9,5. Specifically, at the above rates, the mixer of the present invention not only mixes the slurry but also imparts sufficient energy to the slurry to cause the alkaline composition to react with the polyester. In fact, mixing can be continued until substantially all of the a kaline composition has been exhausted. For example, the mixer c^t\ be operated such that residual (unreacted) rnetai hydroxide exiting the mixer can be less than about 1% by weigh: of the slurry. Specifically, residual metal h/droxide exiting the mi>er can be less than about 0.5% by weight. More specially, residua! rnetai hydroxide can be less than abou: 0.1% by weight oF'.he slurry. In the past, the saponification reaction occurred after heat was added to ;he mixture ir a heaier or kiln. Addition of heat to the mixture prior to reaction however, can cause some of the alkaline solution lo evaporate 3nd thus can requ.re addition of supplementary alkaline compounds to ensure suitable reaction levels. Additionally. th& alkaline compound could become anhydrous during the heating processes. Thus, low oxygen and very dry processing conditions were preferred. The present invention avoids these problems by limiting the amount of caustic supplied to the dryer and/or k>ln. Another of the benefits of the present invention is the increased efficiency of the reaction process. For example, in one embodiment of the present invention a 10% by weight 50% sodium hydroxide/water solution can be added to the mixer with suitably prepared PET materia!. After sufficient mixing at a Froude number of approximately 6.6, about 13% of the PET can read: with the caustic in the mixer. Use of the mixer of the present invention can not only substantially exhaust the alkaline composition within the mixer, but can also lower the amount of the alkaline composition required for the pruceass due to more complete coating of the materials during mixing. Lower amoi/nts of alkaline composition required for the process can mean not only leas of the alkaline compound required in the process, but also lower the wate." requirements for the process. The saponification reaction can convert the polyester into a polyol and an add salt. For instance, when polyethylene terephthalate is reacted with sodium hydroxide, the reacted polyester can be converted to ethylene glycol and oisodium terephthalate. It is believed thai due to the completeness of mixing as well as the substantially even coating of alkaline supplied to the polyester materials in the mixer, the formation of the salt can form a coating on tht polyester materials, which exit the mixer. For example, in an embodiment wherein the outer surface of PET is saponified in the mixer with a sodium hydroxide solution, it is believed that the disodium terephthalate reaction product can coat the remaining PET. Unexpectedly it has been discovered that such a coating formed around a polyester piece can serve to pr:»;eci the polyester during later processing processes. For example, the salt cuatirg can protect the polyester from oxidation due to high temperature -conditions encountered later in the process. Among other benefits: this can ptt'/icie a polyester product with less discoloration than that obtained »n the p£:St. After exiting the mixer, the slurry can bs heated- When heated, the slurry is preferably heated indirectly such that it does not contact an open fteme. Heating the slurry can dry the polyester and the remaining impurities arid can cause the loose, dried impurities to be degraded into a more easily separable form in order to facilitate final separation of the impurities from the polyester product. The actual temperature to which the slurry can be heated can depend upon a number of factors. In general, heating can include more than one hes-tng step. A preferred heating sequence in this regard includes heating to a temperature of 120-17GCC so 3S to dry the polyester, followed by heating, after drying, to a temperature of 20Q-240°C in an environment that can be substantially free of water. The equipment and apparatus used during the process of the present invention can vary. Thus far, good results have been obtained when the saponified slurry is heated In a rotary kiln, in order to provide a two-step heathg process, the kiin can first be heated to the lower temperature for a desired period of time and then the temperature can be increased to the higher level. Alternatively, the slurry exiting the mixer can first be heated in a drysr, such as, for example, a ConAir dryer, before being transferred to a kiln for he higher temperature heating step. The rotary kiln can be heated by an electrical element, by he£:ted oil or by fossil fuel burners. One example of a suitable indirectly heated kiln for use in the process of the present invention is the Rotary Calciner marketed by the Renneburg Division of Heyl & Patterson, Inc IS is believed, however, that a multtdtec thermal processor or an oven will work equally as we!!. Of sourse; many other similar devices are available w'"ich may be used in the process of the present invention. Although not required, the slurry can also be heated in an oxygen-starvud environment. As used heiein, oxygen starved refers to an environment in which oxygen is present balov/ about 19% t>y volume. Maintaining lower oxygen levels during the heating phase prevents th« polyester from being degraded and also protects against uncontrolled combustion. In one embodiment, the mixture can be heated in an inert atmosphere, such as in the presence of a ntrogen blanket, if desired, the rnixtjre can also be heated at reduced pressures, whicn corespond to lower oxygon levels. As described above, the process of the present Invention is particularly directed to separating polyester from polyvinyl chloride, aluminum, coatings adhered to the polyester, and antraineri organic and inorganic compounds. The particular steps involved in separating each of the above impurities according to the process of the present invention will now be discussed. When polyvinyl chloride is present within the materials, during the process of the present invention the polyvinyl chloride can be converted into a form hat floats in water and is heat resistant. It is believed that when the polyvhyl chloride is mixed with the alkaline composition and energy is added in the mixer, the alkaline composition can cause the polyvinyl chloride to dechlorinate, resulting in a darker colored materia! that is water buoyant and has a higher melting point than the chlorinated PVC. Consequently, when polyvinyl chloride is present in the material, enough alkaline composition can be added sufficient to substantially dechlorinate the polyvinyl chloride or, in olnsr words, to convert the polyvinyl chloride into a form separable from the polyester. However, even i': not all of the PVC is contacted with an alkaline composition and dechlorinated during the process of the present invention, when the mixture is heated to the above mentioned temperatures following exit from the rrixer, the PVC which has not been dechlorinated can discolor anc! oe easily separable from the polyester. In one embodiment, after the materials containing the polyvinyl chloride and polyester are mixed with an alkaline composition and heated, in order to s&^arate the now dechlorinated polyvinyl chloride from the polyester, the materials can be washed with water. Tho dechlorinated polyvinyl chloride can float and can be easily separated from the suomerged polyester. Aiso, it has -been Found that treating polyvinyl chloride with an alkaline composition in the above-described manner causes entrained air and other g.N bubbles to have a higher tendency to adhere to the surface of the polyvinyl chloride, making the polyvinyl chloride even more buoyant. Consequently, when the polyvinyl chloride is being separated from the polyester in a liquid, gas bubbles, such a:s air, may be added to the liquid to increase separation efficiency. Of course, other separation techniques based on the differences in density between the polyester and the dechlorinated polyvinyl chloride may also be incorporated into the process. Besides decreasing its density, the process of the present invention aso darkens the color of the polyvinyl chloride and increases its melting point. Consequently, in another embodiment, the dechlorinated polyvinyl chloride can be separated from the polyester by visual inspection. Further, in yet anther alternative embodiment, a mixture containing polyester and the dechlorinated polyvinyl chloride can be heated in order to melt the polyester The haated mixture can then be fed to an extruder. Since the dechlorinated polyvinyl chloride has a much higher melting point than the polyester, the dechlorinated polyvinyl chloride can be captunsd on a screen prior to entering the extruder. In this embodiment, the polyvinyl chloride should be completely dechlorinated to prevent any chlorine from being given off when the polyester is melted. Besides polyvinyl chloride, polyester collected from the solid waste stream is also typically mixed with pieces of aluminum. The aluminum can originate, for instance, from bottle caps associated with polyester containers or from the imperfect separation of plastic and aluminum cans found in discarded matter. Aluminum, similar to polyvinyl chloride, cannot easily be separated from polyester using a sink/float separation technique. When contacted with an alkaline composition and provided with energy, as within the mixer of the present invention, aluminum can be converted to an akaii aluminum salt, which is typically water soluble. Thus, in on<: ombodimani an amount of alkaline composition can be added to materials containing polyester and aluminum sufficient completely convert ths al jminurn salt. a fluid such as water then trio mixture dissolve the salt separate it from polyester.> According to the present invention, however, it has been found that in or:lsr to separate the aluminum from the polyester, it is not necessary to cemp etely convert the aluminum into an aluminum salt, instead, it has been found that reacting a portion of the aluminum with the alkaline composition car cause all of the aluminum pieces to become brittle. After adding energy, the materials containing he polyester and the aluminum can then be washed with £ fluid such as water, preferably under shear conditions., causing the aluminum to be broken into small pieces. The small pieces can be separated fron I he polyester by passing the water mixture through a screen having a size sufficient to capture the larger polyester chips white allowing the smaller alum hum pieces to pass therethrough. Consequently, when aluminum is present within the materials cciiaining the polyester, the alkaline composition should be added to ihe materials in an amount sufficient to react with at least a portion of the aluminum, sufficient to make the aluminum brittle. Of course the actual amount will depend upon the quantity of aluminum present m the materials and tie size of the aluminum pieces. Besides separating aluminum and PVC from polyester, the process of the present invention is also capable of removing various costings adhered to polyester. In particular, the process of the present invention is capable of removing vapo* barrier coatings and screen printed labels from polyester containers. Vapor barrier coatings are typically applied to beverage containers in order to prevent carbon dioxide escape when containing carbo lated beverages and/or prevent oxygen incursion when containing liquids that could spoil in the presence of oxygen. Vapor barier coatings can be: made from saran, polyvinylidene chloride, or an acrylic. Screen printed laijols, on the other hand, generally retef to inks thai are directiy applied to polyester containers, such as beverage containers. For instance, many soft drrik -;ortainers are typically labeled w.th an epoxy based ink. In the past, m =.ny problems have been encountered in attempting to separate the polyester from these coatings and inks. In order to remove the above-described coatings from polyester materials according to the present invention, the polyester is combined w:th ths alkaline composition in an amount sufficient to saponify the outside surface of the polyester and mixed sufficiently to promote the saponification reaction. Any coatings adhered to the polyester become deiaminated when tha outside surface of the polyester is saponified, Once separated from the po'yoster, the coatings are further degraded while the materials are being heated. Specifically, solvents and liquids contained within the coatings are vo ati ized leaving behind some relatively smeller sized impurities. When the materials are later washed with water, the remaining insoluble impurities can bti separated from the larger polyester chips using an appropriately sized screen that allows passage of the impurities while preventing passage of the polyester. Besides various coatings, the process of the present invention is also effective in removing entrained organic and inorganic compounds that may have been absorbed by polyester materials. These compounds can include, for instance, toluene, gasoline, used motor oil, paint, pesticide residues, and other volatile compounds. The compounds can be absorbed by polyester when placed In contact therewith. For instance, consumers often misuse polyester food and beverage containers alter the food or beverage has been consumed. Specifically, the containers are sometimes used to hold various 01 genie and inorganic compounds and solverts. When attempting to recycle frrasa polyesters, it is necessary to remove substantially all of the absorbed organic and inorganic compounds so that the polyester can be once again reused as a beverage container or food container. According to the present invention, entrained organic and inorganic ccm pounds thai may be absorbed into polyester are released from the po'yrner during the saponification process. Specifically, the volatile organic a:id inorganic compounds are substantially removed during the heating steps, sjch as in a Mr. Less volatile compounds and compounds that siowly diffuse froTt polyester, on ihe other hand, are removed by first saponifying the cuter s Jif3ce of the polyester in the mixer and then evaporating any remaining organic and inorganic compounds in the subsequent heating steps. By removing substantially a.l of any entrained organic and inorganic compounds, "food grade" polyester is recovered which can be used in an unrestricted manner. In summary, regardless of the impurities present, the process of the present invention includes contacting materials containing polyester with an alkaline composition, mixing the alkaline mixture and the polyester containing materials together such that the materials are substantially and evenly coated by the composition and partial saponification of the polyester occurs, heating the materials in a one or two step process to a temperature sufficient to chemically convert some of the impurities into a more separable form, and than washing the heated materials with a fluid, such as water. During weishhg, water buoyani contaminants can be separated from the polyester. Also, "he water mixture can be passed through a screen in order to separate smalter sized impurities from the polyester, Besides washing the heated materials with only water, in another embodiment, the heated materials can be washed according to a conventional mechanical recovery process as discussed above For instance, after being heated, the materials containing the polyester can be mixed with a hot acueous solution containing a surfactant or with a hot aqueous solution containing an alkaline composition and washed. It desired, \!"\e mixture can be heated under agitatior. during the wash cycle. Washing the materials can generally dean the polyester and can dissolve and break apart some of the irr purities. During the process, the portion of the polyester that is saponified is converted into a polyoi and «n acid salt. F'or instance, when saponifying PET with sodium hydroxide, the PET is converted into ethylene glycol and di sodium terephthalate. The polyoi (hat is formed during the process either remains as a liquid within the mixture or is evaporated if the mixture is heated above the boiling point of the polyoi. The formed acid salt or metal salt, such as disodium terephthalate. can die-so ve in the water when the materials Bra washed. If desired, the metai sa; can bs later recovered from the wash water. For instance, if the acid salt is a turephth&late, the wash W3ter can first be filtered in order to remove any undissolved impurities and contaminants. Next, the wash water can be acidified caushg terephthalic acid to he precipitated. In order to acidify the soL::ion( a mineral acid such as hydrochloric acid, phosphor C acid or sulfuric add or an organic acid such as acetic acid or carbonic acid can be added to the solution. Once the terephthalic acid precipitates, the terephthalic acid can be filtered, washed and cried, leaving a relatively pure product. These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from th?3 spirit and scope of the present invention, which is more particularly set fo ih in the appended claims. In addition, aspects of the various embodiments may be interchanged both in whole or in pa-£. Furthermore, those of ordinary skill In the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims. WHAT IS CLAIMED IS: 1. A process for releasing contaminants from a polyester substrate comprising: combining materials containing contaminated polyester with an alkaline composition to form a slurry; and mixing said slurry in a high energy mixer, wherein said high energy mixer sjbstantially coats said materials with said alkaline composition and imparts sufficient energy to said materials so as to saponify the outer surface of said polyester and cause said contaminants to be released from said polyester into said si jrry. 2. The process of claim 1, further comprising heating said slurry to a iist temperature to produce a dry product comprising polyester substrate rn : 3. The process of claim 2, wherein said slurry is heated to a first temperature of between about 120~C and about 170oC. 4. The process of claim 2, further comprising heating said dry product to a second ternperafure higher than said first temperature, wherein sad second temperature is below the melting point of said polyester substrate. 5. The process of claim 4, wherein said second temperature is between about 200°C and about 240°C. 6. The process of claim 1, further comprising separating said polyester from said contaminants. 7. The process of claim 1, wherein said contaminants comprise contaminants entrained in said polyester substrate. 8. The process of claim 1, wherein said contaminants comprise coatings adhered to the surface of said polyester substrate. 9. The process of claim 1, wherein said alkaline composition is combined with said materials in a stoichiometric amount sufficient to react witri less than about 20% of the polyester. 10. The process of claim 1, wherein said alkaline composition is combined with said materials in a stoichiometric amount sufficient to react alkaline composition in an amount of less than about 10% by weight of said mate-rials to form a slurry, said alkaline composition comprising at least one metal Hydroxide n a stoichiometric amount sufficient to react with less than about 20% of the polyester; and mixing said slurry in a high energy mixer, wherein said high energy mixer substantially coats said materials with said alkaline composition and imparts sufficient energy to said materials so as to promote a sapor ification reaction between said metal hydroxide and said polyester, said contaminants being released from said polyester upon said reaction, wherein the residual metal hydroxide remaining in said slurry following said reaction is less than about 0.5% by weight of said slurry, heating said slurry to a first temperature to produce a dry product cor:prising polyester substrate mixed with dried contaminants, wherein said firs;; temperature is below the melting point of said polyester substrate; and heating said dry product to a second temperature higher than said first temperature, wherein saic: second temperature is below the melting point of said pDly^ster substrate. 22. The process of claim 21, wherein said slurry is heated to a first tenoerature of between about 120°C and about 170°C. 23. The process o- claim 21, wherein said second temperature is be veen about 200°F and about 240°F. 24 The process of claim 21, wherein said contaminants comprise contaminants entrained in said polyester substrate. 25, The process of claim 21, wherein said contaminants comprise coalings adhered to the surface of said polyester substrate, 26 The process of claim 21, wherein said alkaline composition consists essentially of sodium hydroxide and water. 27. The process of claim 21, wherein said residua! metal hydroxide remaining in said slurry following said reaction is less than about 0.1% by we'ghtof said slurry. 28. The process of claim 21, wherein said mixer operates at a Freed e number g-eater than about 6.6. 29. The process of claim 21, wherein said mixer operates at a Frouce number g-eater than about 9.5. 30 The process of claim 21, wherein said high energy mixer is £ plow mixer. 31. A process for separating polyester from polyvinyl chloride comprising: combining materials containing polyester and polyvinyl chloride with an alkaline composition comprising at least one metal hydroxide tc form a sluny; and nixing said slurry in 3 high energy mixer, wherein said high energy mixer substantially coals said materials with said alkaline composition anil imparts sufficient energy to said material so as to dechio-inate at least a portion of said polyvinyl chloride thereby converting said polyvinyl chloride into a form separable from said polyester. 32. Trie process of claim 31. wherein said alkaline composition is combined with said materials in an amo jn o? less than about 10% by weigh! of said materia s. 33. The process of claim 31, wherein said metai hydroxide is selected from the group consisting of sodium Hydroxide, calcium hydroxide, pclu&siurn hydroxide, lithium hydsoxide, magnesium hydroxide, or mixtures thereof. 34. The process of claim 31. wheren said alkaline composition ccnsisits essentially of sodium hydroxide and water. 35. The process of claim 31. wherein said mixer operates at a Frouce number greater than about 4.2. 36. The process of claim 31, wherein said mixer operates at a Frouce number greater than about 6.6. 37 The process of claim 31, wherein said high energy mixer is a plow Tiixer. 38. A process for separating polyester from aluminum comprising; combining materials containing polyester and aluminum with an alkaline composition comprising at least one melai hydroxide to form a slurry, and mixing said slurry in a high energy mixer, wherein said high energy mixer substantially coats said material** with said alkaline composition and imparts sufficient, energy so said material so as to react with at l«ast a portion of said aluminum thereby converting said aluminum into a form separable from said polyester. 39. The? process; of claim 38, wherein said alkaline composition is combined with said materials in an amount of less than about-10% by weight of said matedas 40. The process; of claim 38, wherein said metal hydroxide is selected from the group consisting of sodium hydroxide, calcium hydroxide, pctassium hydroxide, lithium hydroxide, magnesium hydroxide, or mixtures thereof. 41. The process of claim 38, whereh said alkaiine composition consists essentially of sodium hydroxide and water. 42. The process of claim 38t wherein said mixer operates at a Fro jc!e number greater than about 4.2. 43. The process of claim 38, wn-sre-in said mixer operates at a Frojce number oreater than about 6.6. 44. The process of claim 38, wherein said high energy mixer is a plow mixer. A process for releasing contaminants from a polyester substrate substantially as herein above described and exemplified.

Full Text

PROCESS FOR SEPARATING POLYESTER FROM OTHER MATERIALS
CroasJReference to Related Application
This application claims priority to an earlier filed U.S. provisional patent app-ication Serial Number 60/299273 filed June 19. 2001 entitled, "Process for Separating Polyester from other Materials."
Background of the invention
Polyesters are polymeric materials mado from the eslerification of polvb&sic organic acids with polyhydric acids. Perhaps the most commonly made and used polyester is polyethylene terephthalate (PET),, which can be manufactured by reacting xerephthalic acid with ethylene glycol.
Polyesters are currently being used in ircreasing amounts in various applications. For instance, polyesters are commonly used to Tiake all types of containers such as beverage and fooc containers, photographic films, X-ray films, magnetic recording tapes, electrical insulation, surgical aids such as syr.Viatic arteries, fabrics and other textile products, and other numerous items Because polyesters can be remelted arid reformed, many efforts are jnderv/ay to recycle as much polyester as possible after use. Before pollsters can be recycled, however, it is necessary to separate the post-consumer polyesters from other products and materials that may be found mixrci with or coupled with the polyester. Unfortunately, many problems have betin encountered In attempting to separate polyester from other waste mater .sis. In particular, many prior art processes ar« not capable of efficiently or fiijo-iomicaliy recovering polyester when a significant amount of impurities and ccntaminants are present Most prior art processes for separating polyesters from other materials have been limited to floatation separation techniques and mechanical recovery processes.
In floatation separation techniques; polyesters are separated from other materials based on density differences. For instance, materials containing polyester can be combined with water, in which polyester is known (o sink. The less dense materials, which float rn water, can thus be easily separated from the submerged polyester. This procedure is relatively simple and very effective in separating polyesters from specific low density

impurities, Floatation separation techniques, however, cannot, be used if the polyester is found in combination with materials that sink in water or that have densities comparable to th3t of polyester.
For instance, post consumer polyester is typically mixed with polyvinyl chloride (PVC) and alumin jm, which are not water buoyant. In fact, PVC has a density that is very similar to the density of PET and is often misidentified as PET. Both aluminum and PVC must be separated from polyester before it car be reused. In particular, if PET and PVC are remelted together, hydrochloric acid gases an? produced which destroy the properties of the resulting plastic material.
In the past, in order to separate PET from PVC using a floatation separation technique in a specific gravity bath, others have attempted to modify the surface of the PVC so that the PVC will float in an aerated aqueous medium. For instance, in U.S. Patent No. 5,234,110 to Kobler and U.S Patent No. 5,120,763 tc Sisson various processes for separating PET from PVC flakes are disclosed. !n these processes, the surface of the PVC flakes is treated in a manner so lhat the surface of the PVC is more Hkely to adher-3 to air buDbles when placed in an aqueous medium. In order for these processes to be efficient, however, the PVC flakes must have a high surface area to volume ratio. Consequently, the above processes are deficient in separating PVC c-.ips from PET whan the PVC chips have a large interior voluin®.
Besides failing to separate polyesters from heavier-thai-water impurities, floatatiDn separation techniques also fail to remove coatings that are commonly adhered to polyester. For example, poiyester containers are cor-monly coated with vapor barrier coatings, saran coatings, and/or inks.
Mechanical recovery processes as usee herein are washing processes use a to strip specific binder and adhesive layers off polyester films without substantial reaction occurring between the polyester and the wash solution. For example, U, S. Patent Nos. 5,286,463 and 5,366,993 both to Schwartz, Jr., both of which are incorporated herein by reference thereto, disclose a composition and process for removing adhesives, particularly polyvinylidene

halide and polyvinyl haiide based resins, from polyester films, such as photographic films. In one embodiment, the polyester films are mixed with a reducing sugar and a base to remove the adhesive polymeric resin from the film. An acid is then added to precipitate the resin, which can then be separated from the polyester film.
U.S. Patent No. 4,602,046 to BuseretaL discloses a method for the recovery of polyester from scrap materia! such as photographic film having a polyester base and at Ieas>t one layer of macromoiecular organic polymer. Specifically, scrap material is cut or chopped into small individual pieces or flakes and treated in a caustic alkaline solution at a solids level of at least 25% ':)y voiume and under conditions of high shear. The organic polymer coating material is removed from the polyester flakes. The polyester flakes are then separated from the polymer coating materia! by filtration or centrifugation, rinsed in water, and dried. The recovered polyester flakes can be used as a feed stock for making films, bottles or other polyester articles. A method and apparatus for recovering silver and plastic from used film is aSso disclcsed in U.S. Patent Mo. 4,392,889 to Grout. In this method, the used film is firs? passed through a bath preferably comprising a hot caustic solution for precipitating silver layered on the film. The film then passes through a second bath cf hot caustic until an adhesive sheet disposed on the film has been dissolved. Typically, the adhesive sheet is made of polyvinylidene chloride, which adheres the silver \o the film. After a second caustic bath, the film is dried and available for use.
Other processes for recovering polyester from photographic films are disclosed in U.S. Patent No. 3,928,253 to Thornton otaL U.S. Patent No. 3,652.466 to Hitteletal.. U S. Patent No. 3,647,422 to Wainor. and U.S. Patent No. 3,873,314 to Woo et_aL -
As shown above, mechanical recovery processes have generally been limited.to use with photographic films. In recycling the photographic films, silver is also recovered making the processes economically viable. Mechanical recovery processes, although veiy successful at removing the enul&
successful in removing other types of coatings from polyesters. For instance, most el these processes are not capable of efficiently removing some of the vapor barrier coatings and inks that are applied to polyesters.
Other contaminants that are generally not removable from polyesters using rioatation separation techniques and mechanical recovery processes as de$.crbecl above are entrained organic and inorganic compounds. These contaminants include, for instance, gasoline, kerosene, motor oil, toluene, pefilicides and other compounds that are absorbed by polyesters when placed in contact therewith. If the entrained organic and inorganic compounds are not substantially removed from the polyester materials during recycling, the recycled polyesters cannot be used as food containers or as beverage containers.
Because of the above noted deficiencies in prior art processes, large amounts of recyclable polyesters are being scrapped and loaded into landfills or are being incinerated. Unfortunately, not only is the polyester not being re jsed, but the polyester materials are creating a waste management and disposal problem.
Recently, the focus of recovering polyester from the waste stream has changed from mechanical washing processes to chemically converting the polyester into usable chemical components. For instance, in U.S. Patents No. 5,358.987, 6,147,129, and 6,197.838, all to Schwartz, Jr., which are incorporated herein by reference thereto, processes for recycling polyesters in which a portion of the polyesters are reduced to their original chemical reactants are disclosed. The processes include the steps of combining the polyester materials with an alkaline composition to form a mixture. The mixture is heated to a temperature sufficient to convert the surface of the polyester to an alkaline salt of a polybasic organic acid and a polyol.
The above described patents represent great advancements in the ait The process of the present invention is directed to further improvements in processes for recycling polyesters.

Summary of the Invention
In general, the process of the present invention is directed to a process for separating a poiyester substrate from various contaminants and impurities. For example, the process of the present invention can be used to release var-ous contaminants from a polyester substrate to which the contaminants have been coupled, i.e. either adhered or entrained contaminants. Additionally, the process of the present invention can facilitate the separation of polyester from other contaminants which can be mixed with poiyester in the wE.ste stream; aluminum and polyvinyl chloride, for example.
Tne process of the present invention generally includes mixing materials containing polyester with an alkaline composition to form a slurry. The slurry can Lhen be mixed in a high energy mixer which can not only substantially and evenly coat the materials with the alkaline composition, but can also impart sufficient energy so as to promote reaction between the mater als and the alkaline composition which can enable separation of the poiyester from various contaminants and impurities. For example, the slurry can b$ mixed in a high energy plow mixer. In one embodiment, the mixer can operate at a Froude number greater than about 4.2 to promote the reaction. Specncaliy, the mixer can operate at a Froude number greater than about 6.6. h one embodiment, the'mixer can operate at a Froude lumber greater than about 9.5.
In general, the alkaline composition can be a metal hydroxide solution. For example, the metal hydroxide can be sodium hydroxide, calcium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, or mixtures thereof. In one embodiment, the alkaline composition can be formed of only sodium hydroxide and water. For example, the alkaline composition can be sodium hydroxide and water in a 1:1 ratio.
The alkaline composition can be combined with the polyester materials in an amount so as to saponify as little of the polyester as possible and yet st il promote separation of the polyester from any contaminants or impurities For example, the alkaline composition can be combined with the polyester materials in an amount of less than about 10% by weight of the polyester

materials. Specifically, the alkaline composition can be combined with the polyester materials in a stoichiometric amount sufficient to react with less than about 20% of the polyester. More specifically, the alkaline composition can be combined with the polyester materials in a stoichiometric amount sufficient to react with less than about 10% of the polyester.
The reaction process can substantially exhaust the metal hydroxide in th& mixer. For example, trie metal hydroxide remaining in the slurry aftei the mixing1 and reaction process can generally be less than about 1% of the weigh;; of the slurry. Specifically, the metal hydroxide remaining in the slurry aftsr the mixing and reaction process can generally be less than about 0.5% of Tie weight of the slurry. More specifically, the metal hydroxide remaining in the slurry after the mixing and reaction process can generally be iess than about 0.1 % of tie weight of the slurry,
If desired, the slurry can be heated after the reaction in the mixer is substantially complete. For example, the slurry can be heated to a first temperature, such as, for example, a temperature of between about 12GUC and anout 170°C. to dry the slurry and produce a dry product and then heated to a second temperature, such as, for example a temperature of between about 200°C and about 240°C, which can further degrade the contaninants and make them easier to separate from the polyester substrate.
in one embodiment, the polyester containing materials can include contaninants which are coupled to the polyester substrate, such as contaminants which are entrained in the polyester or contaminants which are adhur esd to the surface of 'tie polyester. In this embodiment, the alkaline composition can react with the materials during mixing and cause saponification of a portion of the polyester which can release the contaminants from the surface of the polyester substrate,
Alternatively, the polyester containing materials can include impurities or cor-:arr inants which are mixed with the polyester, though not necessarily coupled to the polyester, such as polyvinyl chloride or aluminum materials, for exanple. In this embodiment, the alkaline composition can react with the contaminant and cause them to be altered into a form which is more easily

separable from the polyester. For example, polyvinyl chloride can be dechlorinated by the alkaline composition in which form it can be easily separated from the polyester substrate.
Detailed Description of Preferred Embodiments
The present invention is generally directed to a process for recovering and separating polyesters from various contaminants and impurities. For instance, through the process of the present invention, various contaminants can be released from a polyester substrate such as various coalings inducing vapor barrier coatings, inks, and saran coatings as well as other contaminants which are entrained within the outer surface o- the polyester substrate, such as various volatile organic and inorganic contaminants. During the process, the polyester can be partially saponified but largely remain in polymer form and the contaminants car be physically released from the polyester substrate.
The process is aiso directed to the separation and recovery of polyester when mixed with other types of impurities such as polyvinyl chloride and aluminum, for example. During the process, the impurities can be converted into a form which is more easily separable from the polyester substrate.
As used herein, a poiyester is definec as an esterification or reaction product between a poiybasic organic acid and a poiyol. It is believed that any known polyester or copolyester may be used in the process of the present invention. The process of the present invention is particularly directed to a class of polyesters referred to herein as poiyol polyterephtha ates, in which terephthalic acid serves as the poiybasic organic acid.
As used herein, a poiybasic organic acid refers to any organic acid havircj two or mere carboxyf groups (-COOH). Most polyesters are derived from eibasic acids or, in other words, from dicarboxylic acids. Poiybasic acids can have a linear or a cyclic conformation. Examples of linear poiybasic acids that can be used to make polyesters include the aliphatic dicarboxylic acids. In particular the aliphatic dicarboxylic acids having up to ten carbon atoms in their chains can be used. These acids include adipic acid, glutaric acid,

succinic acid, malonic acid, oxalic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, and fumaric acid.
Cyclic pclybasic organic acids, on the other hand, include the carbocycllc tricarboxylic acids. These acids are known as phthalic acid, isophthalic acid, and terephthalic acid, in particular, terephthalic acid is used to make polyethylene terephthalate, which is'perhaps the most commercially available polyester.
As described above, a polybasic organic acid is combined with a polyol to produce a polyester. Polyols are compounds that contain at least two hyciroxyl groups. Many polyesters are synthesized using a polyol that conta'ns two hydroxy! groups, which are referred to as diols. Diois are normally prepared from an alkene by the net addition of two hydroxy groups to the double carbon bond in a method known as hydroxylation. Polyols are commonly referred to as glycols and polyhydric alcohols, Examples of polyols us For exemplary purposes, the following table contains a nonexhaustive iist of commercially available polyesters that may be recovered and recycled according to the present invention. For each polyester, the corresponding polybasic organic add and polyol are provided,
POLYESTER POLYBASIC DIOL
ORGANIC ACID
Polyethylene Terephthalic Acid Ethylene Glycol
Terephthalate
Polyb Jtylene Terephthalic Acid But/lene Glycol
Terephthalate
PETG Copolyester Terephthalic Acid Cydohexane-
dimethanol and Ethylene Glycol
PE3TG Copolyester Terephthalic Acid Cydohexane-
dimethanol
and

Butylene Glycol
>olycyclohexane- Terephthalic Acid Cyciohexane-
linethanol dirnethanoi
ferepnthalate
*EN Polyester Napthalene tricarboxylic Ethylene Glycol
Acid
In general, the process of the present invention includes first combining materials containing polyester with a selected amount of an alkaline solution to form a slurry in a mixer. The mixer chosen is one which can not only provide substantially complete and even coating of the polyester mater als by the alkaline solution, but also can impart sufficient energy to cause a portion of the polyester to saponify, or, in other words, to hydrolyze. Durng saponification, various coatings that may be adhered to the polyester and/or other contaminants which may Ixs entrained within the surface of the polyester can be releasee from the polyester, "f he energy provided from the mixir can also promote reaction between the alkaline solution and other impur ties whicn can be mixed in with the polyester in the SIUT/, such as polyvinyl chloride or aluminum, for example, such that the impurities can be converted to another form, one which is more easily separable from the pclyester substrate. After the reaction within the mixer, the slurry can then be heated, usualiy in a two-step heating process.
The process of the present invention can run continuously or can be set up as a batch system. Practically any materia! containing a polyester can be processed by the present invention including but not limited to, for **Hnole: beverage and food containers, photographic and X-ray films, -ezording tapes, insulation materials, textile fibers and other products. Preferably, the polyester materials are recovered from the solid waste stream, th JS alleviating many environmental concerns and disposal problems. The present invention is particularly directed io recycling food containers and beverage containers made from PET. Through the process of the present invention, polyesters can be separated, recovered and reused from post consumer waste, even when the polyesters are found mixed with polyvinyl

chloride or aluminum, adhered to various coatings, or entrained with various organic and inorganic compounds. Such materials are currently being disposed of in landfills or are being incinerated after use due to a lack of an economical process that will recover the polyester.
Prior to be;ng contacted with the alxaline composition, the materials containing the poiyester can be, if desired, cnopped or ground into a particular size. Sizing of the materials is done solely for the purpose of facilitating handling. Generally speaking, the larger the size of the materials and the less surface area to volume ratio, the less saponification of the polyester will occur later in the process. Consequently, smaller dimensions should be avoided anc iifK! size of the materials should be left as large as practicable. However,
*
it should be understood that all different sizes and shapes of material may be used within the process of the present invention and no one size or shape is required.
Also prior to being combined with Ihe alkaline composition, the materials containing the polyester can be in:me*seu in water or some other fluid in order to separate tha'less dense or lighter materials fron the heavier materials containing the polyester. More particularly, it is known that polyester sinks in water while paper products and other polymers, such as polyoietlns, are water buoyant. Thus, the lighter materials can be easily separatsd from the heavier materials when contacted with a flud. Subjecting the inaisrials to a sink/float separation step prior to contacting :he materials wltt1. the alkaline composition not only can reduce the quantity of materials being processed but also can dean the surface of the materials prior to further processing.
After being sized anc! subjected to a sink/float separation, if desired, the polyester containing materials can be combined and mixed with an alkaline composition to form a slurry, or mixture. Preferably, an alkaline solution can be combined with the materials so as to coat the material surfe.ee. In some applications, the material surface can resist uniform coating due i.c surface tension interaction. In this situation, the alkaline solution has a

tendency to "bead up" on the material surface. The process of the present invention, however, as described below, can overcome this problem.
In accordance with the present invention, it has been discovered that an improved mixing process can be employed which can not only coat the polyester materials with the alkaline solution more completely and evenly, but in addition can impart sufficient energy to the mixture to cause saponification of the outside surface of the polyester to occur within the mixer. For example, mixefis such as those described in U.S. Patent Nos, 4,320,979 to Lucke and 4,189.242 to jjjke, which are herein incorporated in their entirety by reference thereb, may be employed for coating of the polyester materials and saponification of at least a portion of the polyester with an alkaline solution.
The alkaline compound selected for mixing with the materials is preferably sodijrn hydroxde, known commonly as caustic soda. Other metai hydroxides and alkaiines lowever, can be used. Such compounds include calcium hydroxide, magnesium hydroxide, potassium hydroxide, lithium hydroxide or mixtures theeof. The alkaline compound can be added to the polyester materials in solution, if desired. ro; instance, in one embodiment, a metal hydroxide, such as sodium hydroxide, can be mixed with water in about a 1:1 ratio to form the alkaline composition.
The amount of the aikaiine composition added to the materials containing the polyester will depend upon :he type and amount of impurities and contaminants present within the materials. Generally, the aikaiine composition should be added only in an amount sufficient to separate the impurities from the polyester, so as to minimize the saponification of the polyester. In most applications, the alkaline composition is added to the mater als in a stoichiometric amount sufficient to react with up to about 50% of the polyester. For example, the alkaline composition can be added in an amount sufficient to react with less than about 20% of the poyester. Specifically, the alkaline composition can be added in an amount sufficient to react with about less than about 15% of in© polyester. More specifically, the alkaline composition can be added in an amount sufficient to react with less than sbout 10% of the polyester.

One of the benefits of the present invention is the ability of the mixer to coat the polyester materia! without the need of a wetting agent. In the past, a surfactant or wetting agent v/as often employed in order to facilitate the mixing of-:he alkaline composition with the polyester materials. Due to the improved mixing of the present invention, the use of a wetting agent is no longer necr&sary
In one embodiment of the present invention a reactor in the form of a mixer can be utilized. In one particular embodiment, a plow mixer can be used. For example, a plow mixer such as those available from the LSdige Company, the Littieford Day Company, or other known companies can be usod. In one particular embodiment, a mixer such as the Littieford Day KM-42C0 mixer can be utilized. This particular mixer is available from the Llttlefcrd Day Company of Florence, Kentucky Besides a plow mixer, however, it should be understood that various other high energy mixers can be tsed. Similarly, it should be understood that the process can be run as either a continuous or a batch process. An amount of ground or chopped polyester material car be added to the mixer after any desired pretreatment processes have been performed, such as, for example, the floatation separation processes as previously discussed. An alkaline solution can then be added to the mixer with the polyester material. For example, a alkaline solution of 50% NaOH and 50% water can be added to the mixer in an amount up to about 20% by weight of the material containing the polyester, and particularly in an amount less than about 10% by'weight of the material containing the polyester.
The mixer can be operated at a rate which can impart sufficient energy to the mixture so as to substantially eveniy coat the polyester material with the alkaline mixture and promote saponification of the outside surface of the polyester material such that most of the alkaline reactant is exhausted in the mixer. In general, mixers can normally be operated at a preset rotational speed specific to the particular device and adapted to the particular process. In order to maintain equivalent energy input when using different mixers, the dimensionless value Fr (Froude number) Is introduced, instead of the

rotational speed. Fr is a dirnensionless number which describes the ratio of inertial forces to gravitational forces. The Froude number can be described by :h« following formula:
Fr := V2/(gL) wherein Fr is the Froude number, V is the velocity, g is the gravitational acceleration, and L is a characteristic length.
Ir. one embodiment of the present invention, the mixer can be operateu ai a Froude number greater than about 4,2, particularly greater than 6.6, and rroro particularly greater that about 9,5. Specifically, at the above rates, the mixer of the present invention not only mixes the slurry but also imparts sufficient energy to the slurry to cause the alkaline composition to react with the polyester. In fact, mixing can be continued until substantially all of the a kaline composition has been exhausted. For example, the mixer c^t\ be operated such that residual (unreacted) rnetai hydroxide exiting the mixer can be less than about 1% by weigh: of the slurry. Specifically, residual metal h/droxide exiting the mi>er can be less than about 0.5% by weight. More specially, residua! rnetai hydroxide can be less than abou: 0.1% by weight oF'.he slurry.
In the past, the saponification reaction occurred after heat was added to ;he mixture ir a heaier or kiln. Addition of heat to the mixture prior to reaction however, can cause some of the alkaline solution lo evaporate 3nd thus can requ.re addition of supplementary alkaline compounds to ensure suitable reaction levels. Additionally. th& alkaline compound could become anhydrous during the heating processes. Thus, low oxygen and very dry processing conditions were preferred. The present invention avoids these problems by limiting the amount of caustic supplied to the dryer and/or k>ln.
Another of the benefits of the present invention is the increased efficiency of the reaction process. For example, in one embodiment of the present invention a 10% by weight 50% sodium hydroxide/water solution can be added to the mixer with suitably prepared PET materia!. After sufficient mixing at a Froude number of approximately 6.6, about 13% of the PET can read: with the caustic in the mixer. Use of the mixer of the present invention

can not only substantially exhaust the alkaline composition within the mixer, but can also lower the amount of the alkaline composition required for the pruceass due to more complete coating of the materials during mixing. Lower amoi/nts of alkaline composition required for the process can mean not only leas of the alkaline compound required in the process, but also lower the wate." requirements for the process.
The saponification reaction can convert the polyester into a polyol and an add salt. For instance, when polyethylene terephthalate is reacted with sodium hydroxide, the reacted polyester can be converted to ethylene glycol and oisodium terephthalate. It is believed thai due to the completeness of mixing as well as the substantially even coating of alkaline supplied to the polyester materials in the mixer, the formation of the salt can form a coating on tht polyester materials, which exit the mixer. For example, in an embodiment wherein the outer surface of PET is saponified in the mixer with a sodium hydroxide solution, it is believed that the disodium terephthalate reaction product can coat the remaining PET. Unexpectedly it has been discovered that such a coating formed around a polyester piece can serve to pr:»;eci the polyester during later processing processes. For example, the salt cuatirg can protect the polyester from oxidation due to high temperature -conditions encountered later in the process. Among other benefits: this can ptt'/icie a polyester product with less discoloration than that obtained »n the
p£:St.
After exiting the mixer, the slurry can bs heated- When heated, the slurry is preferably heated indirectly such that it does not contact an open fteme. Heating the slurry can dry the polyester and the remaining impurities arid can cause the loose, dried impurities to be degraded into a more easily separable form in order to facilitate final separation of the impurities from the polyester product.
The actual temperature to which the slurry can be heated can depend upon a number of factors. In general, heating can include more than one hes-tng step. A preferred heating sequence in this regard includes heating to a temperature of 120-17GCC so 3S to dry the polyester, followed by heating,

after drying, to a temperature of 20Q-240°C in an environment that can be substantially free of water.
The equipment and apparatus used during the process of the present invention can vary. Thus far, good results have been obtained when the saponified slurry is heated In a rotary kiln, in order to provide a two-step heathg process, the kiin can first be heated to the lower temperature for a desired period of time and then the temperature can be increased to the higher level. Alternatively, the slurry exiting the mixer can first be heated in a drysr, such as, for example, a ConAir dryer, before being transferred to a kiln for he higher temperature heating step. The rotary kiln can be heated by an electrical element, by he£:ted oil or by fossil fuel burners. One example of a suitable indirectly heated kiln for use in the process of the present invention is the Rotary Calciner marketed by the Renneburg Division of Heyl & Patterson, Inc IS is believed, however, that a multtdtec thermal processor or an oven will work equally as we!!. Of sourse; many other similar devices are available w'"ich may be used in the process of the present invention.
Although not required, the slurry can also be heated in an oxygen-starvud environment. As used heiein, oxygen starved refers to an environment in which oxygen is present balov/ about 19% t>y volume. Maintaining lower oxygen levels during the heating phase prevents th« polyester from being degraded and also protects against uncontrolled combustion. In one embodiment, the mixture can be heated in an inert atmosphere, such as in the presence of a n*trogen blanket, if desired, the rnixtjre can also be heated at reduced pressures, whicn corespond to lower oxygon levels.
As described above, the process of the present Invention is particularly directed to separating polyester from polyvinyl chloride, aluminum, coatings adhered to the polyester, and antraineri organic and inorganic compounds. The particular steps involved in separating each of the above impurities according to the process of the present invention will now be discussed.
When polyvinyl chloride is present within the materials, during the process of the present invention the polyvinyl chloride can be converted into a

form hat floats in water and is heat resistant. It is believed that when the polyvhyl chloride is mixed with the alkaline composition and energy is added in the mixer, the alkaline composition can cause the polyvinyl chloride to dechlorinate, resulting in a darker colored materia! that is water buoyant and has a higher melting point than the chlorinated PVC. Consequently, when polyvinyl chloride is present in the material, enough alkaline composition can be added sufficient to substantially dechlorinate the polyvinyl chloride or, in olnsr words, to convert the polyvinyl chloride into a form separable from the polyester. However, even i': not all of the PVC is contacted with an alkaline composition and dechlorinated during the process of the present invention, when the mixture is heated to the above mentioned temperatures following exit from the rrixer, the PVC which has not been dechlorinated can discolor anc! oe easily separable from the polyester.
In one embodiment, after the materials containing the polyvinyl chloride and polyester are mixed with an alkaline composition and heated, in order to s&^arate the now dechlorinated polyvinyl chloride from the polyester, the materials can be washed with water. Tho dechlorinated polyvinyl chloride can float and can be easily separated from the suomerged polyester. Aiso, it has -been Found that treating polyvinyl chloride with an alkaline composition in the above-described manner causes entrained air and other g.*N bubbles to have a higher tendency to adhere to the surface of the polyvinyl chloride, making the polyvinyl chloride even more buoyant. Consequently, when the polyvinyl chloride is being separated from the polyester in a liquid, gas bubbles, such a:s air, may be added to the liquid to increase separation efficiency. Of course, other separation techniques based on the differences in density between the polyester and the dechlorinated polyvinyl chloride may also be incorporated into the process.
Besides decreasing its density, the process of the present invention aso darkens the color of the polyvinyl chloride and increases its melting point. Consequently, in another embodiment, the dechlorinated polyvinyl chloride can be separated from the polyester by visual inspection. Further, in yet anther alternative embodiment, a mixture containing polyester and the

dechlorinated polyvinyl chloride can be heated in order to melt the polyester The haated mixture can then be fed to an extruder. Since the dechlorinated polyvinyl chloride has a much higher melting point than the polyester, the dechlorinated polyvinyl chloride can be captunsd on a screen prior to entering the extruder. In this embodiment, the polyvinyl chloride should be completely dechlorinated to prevent any chlorine from being given off when the polyester is melted.
Besides polyvinyl chloride, polyester collected from the solid waste stream is also typically mixed with pieces of aluminum. The aluminum can originate, for instance, from bottle caps associated with polyester containers or from the imperfect separation of plastic and aluminum cans found in discarded matter. Aluminum, similar to polyvinyl chloride, cannot easily be separated from polyester using a sink/float separation technique.
When contacted with an alkaline composition and provided with energy, as within the mixer of the present invention, aluminum can be converted to an akaii aluminum salt, which is typically water soluble. Thus, in on<: ombodimani an amount of alkaline composition can be added to materials containing polyester and aluminum sufficient completely convert ths al jminurn salt. a fluid such as water then trio mixture dissolve the salt separate it from polyester.> According to the present invention, however, it has been found that in or:lsr to separate the aluminum from the polyester, it is not necessary to cemp etely convert the aluminum into an aluminum salt, instead, it has been found that reacting a portion of the aluminum with the alkaline composition car cause all of the aluminum pieces to become brittle. After adding energy, the materials containing he polyester and the aluminum can then be washed with £ fluid such as water, preferably under shear conditions., causing the aluminum to be broken into small pieces. The small pieces can be separated fron I he polyester by passing the water mixture through a screen having a size sufficient to capture the larger polyester chips white allowing the smaller alum hum pieces to pass therethrough.

Consequently, when aluminum is present within the materials cciiaining the polyester, the alkaline composition should be added to ihe materials in an amount sufficient to react with at least a portion of the aluminum, sufficient to make the aluminum* brittle. Of course the actual amount will depend upon the quantity of aluminum present m the materials and tie size of the aluminum pieces.
Besides separating aluminum and PVC from polyester, the process of the present invention is also capable of removing various costings adhered to polyester. In particular, the process of the present invention is capable of removing vapo* barrier coatings and screen printed labels from polyester containers. Vapor barrier coatings are typically applied to beverage containers in order to prevent carbon dioxide escape when containing carbo lated beverages and/or prevent oxygen incursion when containing liquids that could spoil in the presence of oxygen. Vapor barier coatings can be: made from saran, polyvinylidene chloride, or an acrylic. Screen printed laijols, on the other hand, generally retef to inks thai are directiy applied to polyester containers, such as beverage containers. For instance, many soft drrik -;ortainers are typically labeled w.th an epoxy based ink. In the past, m =.ny problems have been encountered in attempting to separate the polyester from these coatings and inks.
In order to remove the above-described coatings from polyester materials according to the present invention, the polyester is combined w:th ths alkaline composition in an amount sufficient to saponify the outside surface of the polyester and mixed sufficiently to promote the saponification reaction. Any coatings adhered to the polyester become deiaminated when tha outside surface of the polyester is saponified, Once separated from the po'yoster, the coatings are further degraded while the materials are being heated. Specifically, solvents and liquids contained within the coatings are vo ati ized leaving behind some relatively smeller sized impurities. When the materials are later washed with water, the remaining insoluble impurities can bti separated from the larger polyester chips using an appropriately sized

screen that allows passage of the impurities while preventing passage of the polyester.
Besides various coatings, the process of the present invention is also effective in removing entrained organic and inorganic compounds that may have been absorbed by polyester materials. These compounds can include, for instance, toluene, gasoline, used motor oil, paint, pesticide residues, and other volatile compounds. The compounds can be absorbed by polyester when placed In contact therewith. For instance, consumers often misuse polyester food and beverage containers alter the food or beverage has been consumed. Specifically, the containers are sometimes used to hold various 01 genie and inorganic compounds and solverts. When attempting to recycle frrasa polyesters, it is necessary to remove substantially all of the absorbed organic and inorganic compounds so that the polyester can be once again reused as a beverage container or food container.
According to the present invention, entrained organic and inorganic ccm pounds thai may be absorbed into polyester are released from the po'yrner during the saponification process. Specifically, the volatile organic a:id inorganic compounds are substantially removed during the heating steps, sjch as in a Mr. Less volatile compounds and compounds that siowly diffuse froTt polyester, on ihe other hand, are removed by first saponifying the cuter s Jif3ce of the polyester in the mixer and then evaporating any remaining organic and inorganic compounds in the subsequent heating steps. By removing substantially a.l of any entrained organic and inorganic compounds, "food grade" polyester is recovered which can be used in an unrestricted manner.
In summary, regardless of the impurities present, the process of the present invention includes contacting materials containing polyester with an alkaline composition, mixing the alkaline mixture and the polyester containing materials together such that the materials are substantially and evenly coated by the composition and partial saponification of the polyester occurs, heating the materials in a one or two step process to a temperature sufficient to chemically convert some of the impurities into a more separable form, and

than washing the heated materials with a fluid, such as water. During weishhg, water buoyani contaminants can be separated from the polyester. Also, "he water mixture can be passed through a screen in order to separate smalter sized impurities from the polyester,
Besides washing the heated materials with only water, in another embodiment, the heated materials can be washed according to a conventional mechanical recovery process as discussed above For instance, after being heated, the materials containing the polyester can be mixed with a hot acueous solution containing a surfactant or with a hot aqueous solution containing an alkaline composition and washed. It desired, \!"\e mixture can be heated under agitatior. during the wash cycle. Washing the materials can generally dean the polyester and can dissolve and break apart some of the irr purities.
During the process, the portion of the polyester that is saponified is converted into a polyoi and «n acid salt. F'or instance, when saponifying PET with sodium hydroxide, the PET is converted into ethylene glycol and di sodium terephthalate. The polyoi (hat is formed during the process either remains as a liquid within the mixture or is evaporated if the mixture is heated above the boiling point of the polyoi.
The formed acid salt or metal salt, such as disodium terephthalate. can die-so ve in the water when the materials Bra washed. If desired, the metai sa; can bs later recovered from the wash water. For instance, if the acid salt is a turephth&late, the wash W3ter can first be filtered in order to remove any undissolved impurities and contaminants. Next, the wash water can be acidified caushg terephthalic acid to he precipitated. In order to acidify the soL::ion( a mineral acid such as hydrochloric acid, phosphor C acid or sulfuric add or an organic acid such as acetic acid or carbonic acid can be added to the solution. Once the terephthalic acid precipitates, the terephthalic acid can be filtered, washed and cried, leaving a relatively pure product.
These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from th?3 spirit and scope of the present invention, which is more particularly set

fo ih in the appended claims. In addition,
aspects of the various embodiments may be interchanged both in whole or in pa-£. Furthermore, those of ordinary skill In the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.

WHAT IS CLAIMED IS:
1. A process for releasing contaminants from a polyester substrate
comprising:
combining materials containing contaminated polyester with an alkaline composition to form a slurry; and
mixing said slurry in a high energy mixer, wherein said high energy mixer sjbstantially coats said materials with said alkaline composition and imparts sufficient energy to said materials so as to saponify the outer surface of said polyester and cause said contaminants to be released from said polyester into said si jrry.
2. The process of claim 1, further comprising heating said slurry to a iist temperature to produce a dry product comprising polyester substrate rn : 3. The process of claim 2, wherein said slurry is heated to a first temperature of between about 120~C and about 170oC.
4. The process of claim 2, further comprising heating said dry product to a second ternperafure higher than said first temperature, wherein sad second temperature is below the melting point of said polyester substrate.
5. The process of claim 4, wherein said second temperature is between about 200°C and about 240°C.
6. The process of claim 1, further comprising separating said polyester from said contaminants.
7. The process of claim 1, wherein said contaminants comprise contaminants entrained in said polyester substrate.

8. The process of claim 1, wherein said contaminants comprise coatings adhered to the surface of said polyester substrate.
9. The process of claim 1, wherein said alkaline composition is combined with said materials in a stoichiometric amount sufficient to react witri less than about 20% of the polyester.

10. The process of claim 1, wherein said alkaline composition is combined with said materials in a stoichiometric amount sufficient to react

alkaline composition in an amount of less than about 10% by weight of said

mate-rials to form a slurry, said alkaline composition comprising at least one metal Hydroxide n a stoichiometric amount sufficient to react with less than about 20% of the polyester; and
mixing said slurry in a high energy mixer, wherein said high energy mixer substantially coats said materials with said alkaline composition and imparts sufficient energy to said materials so as to promote a sapor ification reaction between said metal hydroxide and said polyester, said contaminants being released from said polyester upon said reaction, wherein the residual metal hydroxide remaining in said slurry following said reaction is less than about 0.5% by weight of said slurry,
heating said slurry to a first temperature to produce a dry product cor:prising polyester substrate mixed with dried contaminants, wherein said firs;; temperature is below the melting point of said polyester substrate; and
heating said dry product to a second temperature higher than said first temperature, wherein saic: second temperature is below the melting point of said pDly^ster substrate.
22. The process of claim 21, wherein said slurry is heated to a first tenoerature of between about 120°C and about 170°C.
23. The process o- claim 21, wherein said second temperature is be veen about 200°F and about 240°F.
24 The process of claim 21, wherein said contaminants comprise contaminants entrained in said polyester substrate.
25, The process of claim 21, wherein said contaminants comprise coalings adhered to the surface of said polyester substrate,
26 The process of claim 21, wherein said alkaline composition consists essentially of sodium hydroxide and water.
27. The process of claim 21, wherein said residua! metal hydroxide remaining in said slurry following said reaction is less than about 0.1% by we'ghtof said slurry.
28. The process of claim 21, wherein said mixer operates at a Freed e number g-eater than about 6.6.

29. The process of claim 21, wherein said mixer operates at a Frouce number g-eater than about 9.5.
30 The process of claim 21, wherein said high energy mixer is £ plow mixer.
31. A process for separating polyester from polyvinyl chloride
comprising:
combining materials containing polyester and polyvinyl chloride with an alkaline composition comprising at least one metal hydroxide tc form a sluny; and
nixing said slurry in 3 high energy mixer, wherein said high energy mixer substantially coals said materials with said alkaline composition anil imparts sufficient energy to said material so as to dechio-inate at least a portion of said polyvinyl chloride thereby converting said polyvinyl chloride into a form separable from said polyester.
32. Trie process of claim 31. wherein said alkaline composition is combined with said materials in an amo jn o? less than about 10% by weigh! of said materia s.
33. The process of claim 31, wherein said metai hydroxide is selected from the group consisting of sodium Hydroxide, calcium hydroxide, pclu&siurn hydroxide, lithium hydsoxide, magnesium hydroxide, or mixtures thereof.
34. The process of claim 31. wheren said alkaline composition ccnsisits essentially of sodium hydroxide and water.
35. The process of claim 31. wherein said mixer operates at a Frouce number greater than about 4.2.
36. The process of claim 31, wherein said mixer operates at a Frouce number greater than about 6.6.
37 The process of claim 31, wherein said high energy mixer is a plow Tiixer.
38. A process for separating polyester from aluminum comprising;

combining materials containing polyester and aluminum with an alkaline composition comprising at least one melai hydroxide to form a slurry, and
mixing said slurry in a high energy mixer, wherein said high energy mixer substantially coats said material** with said alkaline composition and imparts sufficient, energy so said material so as to react with at l«ast a portion of said aluminum thereby converting said aluminum into a form separable from said polyester.
39. The? process; of claim 38, wherein said alkaline composition is combined with said materials in an amount of less than about-10% by weight of said matedas
40. The process; of claim 38, wherein said metal hydroxide is selected from the group consisting of sodium hydroxide, calcium hydroxide, pctassium hydroxide, lithium hydroxide, magnesium hydroxide, or mixtures thereof.
41. The process of claim 38, whereh said alkaiine composition consists essentially of sodium hydroxide and water.
42. The process of claim 38t wherein said mixer operates at a Fro jc!e number greater than about 4.2.
43. The process of claim 38, wn-sre-in said mixer operates at a Frojce number oreater than about 6.6.
44. The process of claim 38, wherein said high energy mixer is a plow mixer.

A process for releasing contaminants from a polyester substrate substantially as herein above described and exemplified.

Documents:

2015-chenp-2003 abstract-duplicate.pdf

2015-chenp-2003 claims-duplicate.pdf

2015-chenp-2003 description (complete)-duplicate.pdf

2015-chenp-2003 descritpion (complete) granted.pdf

2015-chenp-2003 form 18.pdf

2015-chenp-2003-abstract.pdf

2015-chenp-2003-claims.pdf

2015-chenp-2003-correspondnece-others.pdf

2015-chenp-2003-correspondnece-po.pdf

2015-chenp-2003-description(complete).pdf

2015-chenp-2003-form 1.pdf

2015-chenp-2003-form 3.pdf

2015-chenp-2003-form 5.pdf

2015-chenp-2003-other documents.pdf

2015-chenp-2003-pct.pdf

« Previous Patent

Next Patent »

Patent Number

228990

Indian Patent Application Number

2015/CHENP/2003

PG Journal Number

12/2009

Publication Date

20-Mar-2009

Grant Date

13-Feb-2009

Date of Filing

17-Dec-2003

Name of Patentee

UNITED RESOURCE RECOVERY CORPORATION

Applicant Address

5396 NORTH BLACKSTOCK ROAD, SPARTANBURG, SOUTH CAROLINA 29303,

Inventors:

#	Inventor's Name	Inventor's Address
1	HOLMES, JOHN, M, III	104 BRIARWOOD CT., SPARTANBURG, SOUTH CAROLINA 29302,
2	ZINK, RICHARD P	324 HOLLY DR. SPARTANBURG, SOUTH CAROLINA 2930,

PCT International Classification Number

C08J 11/04

PCT International Application Number

PCT/US02/19309

PCT International Filing date

2002-06-19

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	60/299,273	2001-06-19	U.S.A.