Copolyesters produced from recycled copolyester

Abstract

A method for producing a polyester composition from recycled polyester.

Description

Field of the Invention

[0001] The present disclosure relates generally to the field of polymer chemistry. In particular, it relates to a method for making copolyesters from recycled polyesters and copolyesters. Background of the Invention

[0003] Polyesters are generally considered to be the most purchased and diverse class of polymers in the world, with recently reported published world production (including recycling) well over 75 million tons. This degree of commercial success is likely due in part to the attractive combination of polyester's relative cost, manufacturability, and competitive performance attributes. The physical, chemical, and thermal properties of polyesters make them useful and desirable for a wide variety of end-use applications. Polyethylene terephthalate (PET) is one of the most popular polyester types for many end-uses. The continued commercial success of polyesters in general and PET in particular has led to efforts to recycle waste materials from post-consumer and post-industrial sources as well as other sources and reuse these materials as an alternative to primary disposal methods such as landfills.

[0004] In some known recycling methods, recycled PET is blended with virgin materials. This method has been used, for example, to prepare blends of virgin poly(butylene terephthalate) ("PBT") and recycled PET to produce PBT-based products with recycled content (see, for example, U.S. Patent Application Publication No. 2009 / 0275698). However, such blends are generally immiscible and produce relatively opaque materials. Therefore, blending is not a consistently satisfactory method for providing commercially acceptable end products with recycled content.

[0005] In other recovery processes, the polyester is depolymerized to form the monomer units originally used in its manufacture. One commercially used polyester depolymerization process is methanolysis. In methanolysis, the polyester is reacted with methanol to produce a depolymerized polyester mixture comprising polyester oligomers, dimethyl terephthalate ("DMT"), and ethylene glycol ("EG"). Other monomers, such as 1,4-cyclohexanedimethanol ("CHDM") and diethylene glycol may also be present, depending on the composition of the polyester in the methanolysis feed stream. Some representative processes for methanolysis of PET are described in U.S. Patent Nos. 3,037,050; 3,321,510; 3,776,945; 5,051,528; 5,298,530; 5,414,022; 5,432,203; 5,576,456 and 6,262,294, the contents and disclosures of which are incorporated herein by reference. Representative methanolysis processes are also exemplified in U.S. Pat. No. 5,298,530, the contents and disclosure of which are incorporated herein by reference. The '530 patent describes a method for recovering ethylene glycol and dimethyl terephthalate from waste polyester. The method includes the steps of dissolving the waste polyester in ethylene glycol and oligomers of terephthalic acid or dimethyl terephthalate and passing superheated methanol through the mixture. The oligomers may comprise any low molecular weight polyester polymer having the same composition as the waste material used as the starting component, such that the waste polymer will dissolve in the low molecular weight oligomers. Dimethyl terephthalate and ethylene glycol are recovered from the methanol vapor stream exiting the depolymerization reactor.

[0006] Another method of depolymerizing polyesters is glycolysis, in which a polyester is reacted with a diol, such as ethylene glycol or CHDM, to produce a depolymerized polyester mixture. U.S. Pat. No. 4,259,478 thus discloses a method comprising heating a polyester in the presence of 1,4-cyclohexanedimethanol to glycolize the polymer, distilling off ethylene glycol from the diol alcoholysis mixture, and polycondensing the diol alcoholysis mixture to form a copolyester, at least a portion of the ethylene glycol units of which are replaced by 1,4-cyclohexanedimethanol units. Similarly, U.S. Pat. No. 5,635,584 discloses reacting a post-consumer polyester or waste polyester with a diol to produce a monomer or low molecular weight oligomer by depolymerization of the polyester. The monomer or oligomer, as the case may be, is then purified using one or more steps, including filtration, distillation, crystallization, and optional adsorbent treatment or evaporation. The monomer or oligomer thus produced is particularly suitable as a raw material for the production of acid-based or ester-based polyesters for packaging grade polyester materials. Since the method includes a purification step, the specifications for the recycled polyester material do not need to be strict.

[0007] Another method of reusing waste polyester is to introduce the waste into a polymerization process. U.S. Pat. No. 5,559,159 thus discloses the depolymerization and repolymerization of previously used poly(ethylene terephthalate) polyester materials and copolymers thereof, and in particular post-consumer polyester materials to produce bottle-grade polymers containing up to 75% previously used materials. The method involves the solubilization and depolymerization of previously used polyester materials in an esterification and / or polymerization mixture containing dimethyl terephthalate, ethylene glycol and their ester exchange products. U.S. Pat. No. 5,945,460 discloses a method for producing polyester articles with little or no generation of polyester waste. The method provides for esterification or transesterification of one or more dicarboxylic acids or their dialkyl esters, polycondensation to produce high molecular weight polyesters, and molding or forming of the polyester to produce the desired product. Waste generated during the molding process is recycled back to the esterification or transesterification or polycondensation portion of the method. Optionally, the waste may also be recycled to an intermediate step prior to the molding operation. U.S. Patent No. 7,297,721 discloses a method for preparing high molecular weight crystalline PET: it uses up to 50% of post-consumer recycled PET flakes together with purified terephthalic acid (PTA), isophthalic acid and ethylene glycol as virgin raw materials in the presence of a combination of catalysts and additives to obtain an intermediate prepolymer heel with a low degree of polymerization, further subjected to autoclaving to produce an amorphous melt, followed by solid state polymerization.

[0008] Nevertheless, there remains a continuing need for alternative and / or improved methods of producing high quality copolyesters utilizing recycled copolyesters.This demand for recycled content has led to the need to develop new methods and processes for capturing existing plastic waste streams and converting them into new plastic products.

[0009] The present disclosure addresses this need as well as other needs, as will become apparent from the following description and the appended claims. SUMMARY OF THE INVENTION

[0011] One aspect of the present disclosure is a method for preparing a copolyester from a recycled copolyester. One aspect of the present disclosure is a method for preparing a copolyester from a recycled polyester and / or a recycled copolyester.

[0012] In one aspect, the present disclosure provides a method for preparing a linear high molecular weight copolyester from one of the following materials: (A) a recycled polyester and / or a recycled copolyester whose acid component consists of at least 70 mol % terephthalic acid and whose diol component consists of at least 70 mol % ethylene glycol, or (B) a recycled copolyester whose acid component consists of at least 70 mol % terephthalic acid and whose diol component consists of at least 70 mol % of a mixture of ethylene glycol, 1,4-cyclohexanedimethanol and diethylene glycol in a molar ratio of 96:3:1 to 20:68:12, or (C) A recycled copolyester whose acid component consists of at least 70 mol% of terephthalic acid and whose diol component consists of at least 70 mol% of a mixture of two or more diols including ethylene glycol (EG), diethylene glycol (DEG), 1,4-cyclohexanedimethanol (CHDM), neopentyl glycol (NPG) or 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD), butanediol and isosorbide, or (D) a recycled copolyester whose acid component consists of at least 70 mol% of terephthalic acid and whose diol component consists of at least 70 mol% of a mixture of ethylene glycol, 1,4-cyclohexanedimethanol in a molar ratio of 3.5:96.5 to 100:0.

[0013] The method provides a fast polymerization rate, and the polymers produced therefrom can be used to make plastics, fibers, films, shrinkable films, sheets, moldings, and other shaped articles having good physical properties. In one aspect, the disclosed method describes a method for converting post-industrial and post-consumer waste products into high-quality copolyester resins that can be used to make new plastics with high levels of recycled content. In another aspect, the disclosed method describes a method for converting post-industrial and post-consumer waste products into resins that can be used to make high-quality shrinkable films.

[0014] One aspect of the present disclosure is a method for producing a copolyester from a recycled copolyester, comprising:

[0015] (a) introducing recycled PET, recycled PETG, recycled PCT, recycled PCTG, recycled PCTA, recycled PCTM and / or recycled PETM; terephthalic acid (TPA); and ethylene glycol (EG) into a paste tank to form a slurry, which is stirred and heated at a temperature of up to 150° C.;

[0016] (b) transferring the paste tank slurry to the first reaction zone;

[0017] (c) introducing into the first reaction zone at least one additional diol comprising 1,4-cyclohexanedimethanol (CHDM), neopentyl glycol (NPG), or 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD), and optionally adding additional recycled PET, recycled PETG, recycled PCTM, and / or recycled PETM; terephthalic acid (TPA); and ethylene glycol (EG) at a molar ratio of EG:TPA of 1:1 to 4:1, and optionally a catalyst;

[0018] (d) reacting TPA with EG and the at least one additional diol (e.g., CHDM) in a first reaction zone at a melt temperature of at least 200° C. and a pressure of up to 40 psi to form a first esterification product comprising oligomers and unreacted TPA, EG, and the additional diol (e.g., CHDM);

[0019] (e) conveying the first esterification product to a second reaction zone;

[0020] (f) esterifying unreacted TPA, EG, and additional diol (e.g., CHDM) in the first esterified product in a second reaction zone at a melt temperature of at least 200° C. and a pressure of up to 20 psi to form a second esterified product comprising a copolyester oligomer;

[0021] (g) conveying the second esterification product to a third reaction zone;

[0022] (h) polycondensing the second esterification product in a third reaction zone, optionally in the presence of a polycondensation catalyst, to form a prepolymerization product comprising a copolyester;

[0023] (i) The prepolymer product is passed to one or more finishing zones.

[0024] One aspect of the present disclosure is the method of any one of the preceding aspects, wherein the method further comprises adding a catalyst or additive via the addition of recycled polyester, wherein the catalyst or additive is a component of the recycled polyester; such as Sb, Ti, Co, Mn, Li, Al, P.

[0025] One aspect of the present disclosure is a method of introducing or establishing recycled content in a polyester made by the method described in the preceding aspects, comprising:

[0026] a. obtaining a recycled monomer allocation or credit for at least one recycled monomer including TPA, EG, DMT, CHDM, NPG or DEG;

[0027] b. converting the recovered monomer in a synthesis process to produce a polyester;

[0028] c. marking at least a portion of the polyester as corresponding to at least a portion of a recycled monomer quota or credit; and

[0029] d. Optionally, offering for sale or selling polyester containing or obtained by recycled monomer content corresponding to such designation.

[0030] An aspect of the present disclosure is any of the preceding aspects, wherein the amount of recycled polyester added to the process is 5-100% based on the amount of TPA required. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 are flow charts of various methods according to the present disclosure.

[0033] Figure 2 . Sb catalyst levels in the final material as a function of rPET starting material loading levels. DETAILED DESCRIPTION OF THE INVENTION

[0035] It has surprisingly been found that high quality copolyester resins can be produced from recycled copolyesters and / or recycled polyesters.

[0036] In one embodiment, the recycled polyester and / or copolyester can be recycled as manufacturing scrap or industrial waste or post-consumer recycled (PCR) waste. Typically, PCR or recycled waste is articles made from polyester or copolyester that have been used and discarded. Today, PET is recycled by mechanical methods and incorporated into new PET bottles and other PET articles as a blend with virgin material.

[0037] Copolyesters with recycled content and copolyesters made from recycled content contain dicarboxylic acid monomer residues, diol or glycol monomer residues and repeating units. Therefore, the term "monomer residue" as used herein refers to the residue of a dicarboxylic acid, a diol or glycol, or a hydroxycarboxylic acid. As used herein, "repeat unit" refers to an organic structure having 2 monomer residues bonded via a carbonyl group. The copolyesters of the present disclosure contain acid residues (100 mol %) and diol residues (100 mol %) in substantially equal molar proportions, which react substantially in equal proportions so that the total molar number of repeating units is equal to 100 mol %. Therefore, the molar percentages provided in the present disclosure may be based on the total molar number of acid residues, the total molar number of diol residues, or the total molar number of repeating units. For example, a copolyester containing 30 mol % monomers (which may be dicarboxylic acids, diols, or hydroxycarboxylic acids) based on total repeating units means that the copolyester contains 30 mol % monomers in a total of 100 mol % repeating units. Therefore, there are 30 moles of monomer residues in every 100 moles of repeating units. Similarly, a copolyester containing 30 mole % dicarboxylic acid monomers based on total acid residues means that the polyester contains 30 mole % dicarboxylic acid monomers out of a total of 100 mole % acid residues. Thus, in the latter case, there are 30 moles of dicarboxylic acid monomer residues for every 100 moles of acid residues.

[0038] The term "polyester" as used herein encompasses "homopolymers" and "homopolyesters" and "copolyesters" and refers to a synthetic polymer made by the polycondensation of at least one diacid component comprising one or more difunctional carboxylic acids and at least one diol component comprising one or more difunctional hydroxyl compounds. The term "copolyester" as used herein means a polyester formed by the polycondensation of at least 3 different monomers, such as a dicarboxylic acid with two or more diols, or in another example, a diol with two or more different dicarboxylic acids. Typically, the difunctional carboxylic acid is a dicarboxylic acid and the difunctional hydroxyl compound is a dihydric alcohol, such as a glycol and a diol. Alternatively, the difunctional carboxylic acid may be a hydroxycarboxylic acid, such as p-hydroxybenzoic acid, and the difunctional hydroxyl compound may be an aromatic nucleus with 2 hydroxyl substituents, such as hydroquinone. The term "residue" as used herein refers to any organic structure incorporated into a polymer by a polycondensation reaction involving the corresponding monomers. The dicarboxylic acid residue may be derived from a dicarboxylic acid monomer or its associated acyl halide, ester, salt, anhydride, or mixture thereof. For example, in one embodiment, for the copolyesters of the present disclosure, the diacid component is supplied as terephthalic acid or isophthalic acid.

[0039] The recycled polyester and / or copolyester can be repolymerized into copolyester using any polycondensation reaction conditions known in the art. They can be manufactured by continuous, semi-continuous and intermittent operation modes and can utilize various reactor types. Examples of suitable reactor types include, but are not limited to, stirred tanks, continuous stirred tanks, slurry reactors, tubular reactors, wiped-film reactors, falling film reactors or extrusion reactors. The term "continuous" as used herein refers to a method in which reactants are introduced in an uninterrupted manner and products are removed simultaneously. For economic reasons, the method is advantageously operated as a continuous process and produces excellent coloring of the polymer, because the appearance of the copolyester may deteriorate if allowed to stay in the reactor for too long at elevated temperatures.

[0040] The copolyesters disclosed herein are prepared by procedures known to those skilled in the art. The reaction of the diol component and the dicarboxylic acid component can be carried out using conventional copolyester polymerization conditions. For example, when the copolyester is prepared by means of an ester exchange reaction, such as from the ester form of the dicarboxylic acid component, the reaction process may include two steps. In the first step, the diol component and the dicarboxylic acid component, such as terephthalic acid, react at an elevated temperature of about 150° C. to about 250° C. at a pressure of about 0.0 kPa gauge to about 414 kPa gauge (60 pounds per square inch, "psig") for about 0.5 to about 8 hours. The temperature for the ester exchange reaction is about 180° C. to about 230° C. for about 1 to about 4 hours, while the pressure is about 103 kPa gauge (15 psig) to about 276 kPa gauge (40 psig). Thereafter, the reaction product is heated at a higher temperature and reduced pressure to form a copolyester while eliminating the diol, which is easily volatile and removed from the system under these conditions.

[0041] The second step or polycondensation step is continued for about 0.1 to about 6 hours, or about 0.2 to about 2 hours, at a higher vacuum and a temperature of typically about 230°C to about 350°C, or about 250°C to about 310°C, or about 260°C to about 290°C, until a polymer having the desired degree of polymerization as determined by intrinsic viscosity is obtained. The polycondensation step may be conducted under reduced pressure of about 53 kPa (400 Torr) to about 0.013 kPa (0.1 Torr). Agitation or appropriate conditions are used in both stages to ensure adequate heat transfer and surface renewal of the reaction mixture, and to remove water, excess diol or alcohol to promote reaction and polymerization. The reaction rates of both stages are enhanced by appropriate catalysts, such as alkoxytitanium compounds, alkali metal hydroxides and alcoholates, salts of organic carboxylic acids, alkyl tin compounds, metal oxides, and the like. A three-stage manufacturing procedure similar to that described in U.S. Pat. No. 5,290,631 may also be used, particularly when a mixed monomer feed of acid and ester is used.

[0042] In order to ensure that the reaction of the diol component and the dicarboxylic acid component by the transesterification reaction is driven to completion, it is sometimes necessary to use about 1.05 to about 2.5 moles of the diol component relative to 1 mole of the dicarboxylic acid component, and then remove the excess diol in a subsequent step. However, those skilled in the art will understand that the ratio of the diol component to the dicarboxylic acid component generally depends on the design of the reactor in which the reaction process is carried out.

[0043] When the copolyester is prepared by direct esterification, for example from the acid form of the dicarboxylic acid component, the copolyester is prepared by reacting a dicarboxylic acid or a mixture of dicarboxylic acids with a diol component or a mixture of diol components. The reaction is conducted at a pressure of about 7 kPa gauge (1 psig) to about 1379 kPa gauge (200 psig), or less than 689 kPa (100 psig) to produce a low molecular weight linear or branched copolyester product having an average degree of polymerization of about 1.4 to about 10. The temperature used during the direct esterification reaction is about 180° C. to about 280° C., or about 220° C. to about 270° C. This low molecular weight polymer can then be polymerized by a polycondensation reaction.

[0044] In some embodiments, suitable glycols include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, p-xylene glycol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethylcyclobutane-1,3-diol, polytetramethylene glycol, isosorbide, or mixtures thereof.

[0045] In some embodiments, copolyesters including the following diacids are suitable for use in a repolymerization process or a polymerization process to make new copolyesters with recycled content: terephthalic acid, isophthalic acid, trimellitic anhydride (or acid), naphthalene dicarboxylic acid, and 1,4-cyclohexane dicarboxylic acid.

[0046] In some embodiments, copolyesters including the following diols are suitable for use in a repolymerization process or a polymerization process to make new copolyesters with recycled content: ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, terephthalylinol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethylcyclobutane-1,3-diol, polytetramethylene glycol, isosorbide, or mixtures thereof.

[0047] In one embodiment, recycled scraps containing terephthalate polyesters and / or copolyesters may be used in the repolymerization process. In one embodiment, any conventionally prepared terephthalate polyester or copolyester may be used in the repolymerization process. In one embodiment, suitable terephthalate polyesters and / or copolyesters include poly(ethylene terephthalate) (PET), glycol-modified polyethylene terephthalate (PETG), poly(cyclohexylene dimethylene terephthalate), glycol-modified poly(cyclohexylene dimethylene terephthalate) (PCTG), poly(cyclohexylene dimethylene terephthalate), acid-initiated (acid) ...PETG), poly(cyclohexylene dimethylene terephthalate), poly(cyclohexylene dimethylene terephthalate) (PCTG), poly(cyclohexylene dimethylene terephthalate), acid-initiated (acid) poly(cyclohexylene dimethylene terephthalate) (PETG), poly(cyclohexylene dimethylene terephthalate), In one embodiment, the terephthalate polyester is poly(ethylene terephthalate) (PET). In one embodiment, the copolyester is PETG. In one embodiment, the copolyester is PCT. In one embodiment, the copolyester is PCTG. In one embodiment, the copolyester is PCTA. In one embodiment, the copolyester is PCTM. In one embodiment, the copolyester is PETM.

[0048] In one embodiment, a mixture of terephthalate polyesters and copolyesters are repolymerized together in a combined manner. In one embodiment, PET and PETG are repolymerized together in a combined manner. In one embodiment, PET and PETM are repolymerized together in a combined manner. In one embodiment, PET and PCT are repolymerized together in a combined manner. In one embodiment, PET and PCTA are repolymerized together in a combined manner. In one embodiment, PET and PCTG are repolymerized together in a combined manner. In one embodiment, PET and PCTM are repolymerized together in a combined manner. In one embodiment, PET and PETG and PETM are repolymerized together in a combined manner. In one embodiment, PET and PETG and PCTM are repolymerized together in a combined manner. In one embodiment, PET, PETG, PCTM, and PETM are repolymerized together in a combined manner.

[0049] In one embodiment, copolyesters suitable for use in the present disclosure are prepared from monomers such as dimethyl terephthalate (DMT), terephthalic acid (TPA), isophthalic acid (IPA), 1,4-cyclohexanedicarboxylic acid (CHDA), ethylene glycol (EG), diethylene glycol (DEG), neopentyl glycol (NPG), 1,4-cyclohexanedimethanol (CHDM), and 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD).

[0050] One embodiment of the present disclosure is directed to a method of making a copolyester having a high level of recycled content by repolymerizing waste or post-consumer polyesters including terephthalate-containing polyesters (e.g., PET) and / or copolyesters (e.g., PETG) with water or an alcohol or glycol and using recycled monomers to make a copolyester containing a high mole percentage of recycled monomer residues.

[0051] In one aspect of the present disclosure, a high molecular weight copolyester containing a diol and a diacid component, wherein the diol component comprises ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl trans-1,4-cyclohexanedicarboxylate, 1,6-hexanediol, terephthalylenol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethylcyclobutane-1,3-diol, polytetramethylene glycol, hexanediol, Diacids, isosorbide and mixtures thereof, and the diacid component comprises dimethyl terephthalate, terephthalic acid, isophthalic acid (IPA), trimellitic anhydride (or trimellitic acid), salts of 5-(sulfo)isophthalic acid (SIPA), naphthalene dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid and mixtures thereof; when a depolymerization aid or solvent such as water, alcohol or excess diol is introduced under conditions where a reversible transesterification reaction can occur, depolymerization will occur by hydrolysis, alcoholysis or glycolysis, thereby reducing the chain length (molecular weight) of the polymer. With a sufficient amount of solvent, the reaction will proceed to a degree where the mixture is mainly composed of the monomer, i.e., the diester of the diol and the acid component. In one aspect, the diols of the mixture include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, dimethyl 1,4-cyclohexanedicarboxylate, trans-dimethyl 1,4-cyclohexanedicarboxylate, 1,6-hexanediol, terephthalyol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethylcyclobutane-1,3-diol, polytetramethylene glycol, adipic acid, isosorbide, and mixtures thereof. In one embodiment, the diols of the mixture include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethylcyclobutane-1,3-diol, and mixtures thereof. In one embodiment, the diols of the mixture include ethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethylcyclobutane-1,3-diol, and mixtures thereof. These recycled monomers can then be used to prepare copolyesters containing a high mole percentage of recycled monomer residues.

[0052] The present invention relates to a method for utilizing recycled polyethylene terephthalate (PET) and recycled glycol-modified polyethylene terephthalate copolyester (PETG), especially post-consumer waste, in the production of linear high molecular weight copolyesters. There is an increasing demand for using higher amounts of recycled materials in plastic products. This demand for recycled content has led to the need to develop new methods and processes for capturing existing plastic waste streams and converting them into new plastic products. The recycling of PETG waste is of particular interest. In recent years, due to the problems encountered in the processing of these combined waste streams, legislation has attempted to separate recycled glycol-modified PET (PETG) waste from recycled polyethylene terephthalate (PET) waste with resin identification code (RIC) 1. In addition, there is a large amount of PETG that is not recycled today, which can be recycled and converted into new plastic products. In particular, shrinkable films made from PETG contain inks and other contaminants that must be removed from the recycling stream to produce high-quality transparent recycled PET (rPET). In addition, medical packaging is made of a large proportion of PETG, and there is currently no recycling stream for this material. The present invention provides a method for using recycled PETG and recycled PETG in combination with PET as a reactive intermediate in the production of copolyesters that can be used to make extruded and injection molded products such as shrinkable films, fibers, durable goods and other shaped articles and items.

[0053] There is a very well defined and large-scale mechanical recycling process today whereby polyethylene terephthalate (PET) products are recovered and converted into semi-crystalline recycled PET (rPET) and further incorporated into new plastic products. Diol modification of PET with other diols such as 1,4-cyclohexanediol, diethylene glycol, butanediol or neopentyl glycol is a very common process to improve the clarity of PET, improve toughness and reduce crystallinity. These diol-modified materials are often referred to as diol-modified PET or PETG. Although the chemical composition of these materials is very similar to PET, modification with diols other than ethylene glycol produces materials that are difficult to recycle in PET recycling processes. New methods must be created to recycle and reuse these PETG materials.

[0054] The method described in the present disclosure uses recycled PETG as a raw material feed to make various new copolyester resins. In this method, recycled PETG (rPETG) is introduced as a paste together with ethylene glycol and terephthalic acid to feed the transesterification reactor at the beginning of the manufacturing process for producing new copolyesters. During the process of the method, the added diol decomposes the rPETG into its original acid and diol residue starting materials, new diols and acids are added, and then the mixture is esterified and polymerized to produce new copolyesters. This method has the advantage of using recycled PETG as a raw material without the need for further purification of the acid and diol produced. In addition, this method is advantageous because it provides a method for using rPETG that currently has no mechanical recovery stream and is therefore thrown into landfills.

[0055] In addition, rPETG (or rPCTG, or rPCTM, or rPETM, or rPCTA, or rPCTG, or rPCT) contains two or more higher value monomers that are not present in rPET, such as CHDM, TMCD, DEG and NPG. The PETG product made by this method behaves the same as virgin PETG and can be used in exactly the same applications without sacrificing any performance due to the addition of recycled materials. Traditionally, rPETG is blended with virgin materials to form physical blends. These blends often lose performance in terms of mechanical properties or color and appearance, and often cannot be used in the same applications as virgin materials.

[0056] It has become a commercial requirement to use previously used, particularly post-consumer PET, in the synthesis of new PET for making water and carbonated beverage bottles. Several chemical treatment techniques are known to facilitate the regeneration and recycling of previously used polyester materials. These techniques are used to depolymerize the recycled polyester material, thereby reducing the polyester material to its monomer and / or oligomer components. The monomer and / or oligomer components can then be repolymerized to produce recycled polyester material.

[0057] One known depolymerization technology is to subject recycled PET to methanolysis. According to the methanolysis process, rPET is reacted with methanol to produce dimethyl terephthalate (DMT) and ethylene glycol (EG). DMT and EG can be easily purified and then used to produce recycled polyester materials containing PET. However, most conventional commercial PET production facilities around the world are designed to use terephthalic acid (TPA), and some smaller-scale facilities use DMT, but most facilities are not designed to use TPA and DMT as monomer feedstocks at the same time. Therefore, additional processing is usually required to convert DMT into TPA, which is required as a feedstock for many such facilities, and in either case, further purification of the diols and DMT / TPA is required.

[0058] Another known depolymerization technique is hydrolysis, whereby recycled PET is reacted with water to depolymerize rPET into TPA and EG. However, it is known that it is very difficult and expensive to remove certain types of contaminants that are typically present in recycled PET from TPA. Also, for those facilities designed to use DMT as a feedstock, TPA must be converted to DMT, and further purification of the diols and DMT / TPA is required.

[0059] Glycolysis can also be used to depolymerize recycled PET. Glycolysis occurs when rPET is reacted with EG, thereby producing bis(2-hydroxyethyl)terephthalate (BHET) and / or its oligomers. Glycolysis has some significant advantages over methanolysis or hydrolysis, primarily because BHET can be used as a feedstock for DMT-based or TPA-based PET production processes without requiring major modifications to the production facility or further purification. Another significant advantage offered by the glycolysis technology is that it is not necessary to remove the glycol from the depolymerization solvent.

[0060] Previously known glycolysis processes include separate complete glycolysis of post-consumer rPET and subsequent addition of a portion of the glycolysis product to a polycondensation process. Such a glycolysis process is described in U.S. Pat. No. 5,223,544. Such a process requires high pressure and a large excess of ethylene glycol. These requirements reduce reactor efficiency by reducing the potential production capacity of the reactor.

[0061] It has generally been found that high temperatures and large excesses of EG are required in these glycolysis processes to dissolve the polyester molecules so that they can then be broken down into their component parts, such as BHET and its oligomers. High temperatures and excess EG result in the production of large amounts of diethylene glycol as a by-product. The diethylene glycol thus produced cannot be easily removed from the BHET, and therefore, if the BHET is subsequently used to produce recycled PET, the resulting PET product has too much diethylene glycol content to make the polymer unusable for many commercial uses.

[0062] Other known processes involving glycolysis require that a tail of BHET oligomers having a degree of polymerization greater than 10 remain in the reactor at the end of the reaction run in order to dissolve the post-consumer rPET, since the latter is insoluble in most solvents. These procedures are described in U.S. Pat. No. 4,609,680. Thus, there is clearly still a need in the art for a glycolysis process that can efficiently process previously used post-consumer rPET in the manufacture of new packaging grade PET.

[0063] The present disclosure provides solutions to the above problems. In particular, the method of the present disclosure provides an efficient and economical procedure for producing packaging grade polyester products using recycled polyester and / or recycled copolyester, including recycled PET, recycled PETG, recycled PETM and recycled PCTM or a mixture of these materials.

[0064] In one embodiment, the viscosity of the material in the paste zone and the viscosity of the material leaving the paste zone is greatly reduced when using rPETG (and rPC™ or a blend with rPET) compared to using rPET alone. In one embodiment, TPA dissolves faster in rPET than in EG alone. In one embodiment, TPA can dissolve faster in rPETG, rPETM or rPC™.

[0065] In one embodiment, TPA is completely replaced by recycled polyester or copolyester.

[0066] In one embodiment, composition control of the final polyester product is performed by a combination of recycling the feed and adding components to the first reaction zone.

[0067] In one embodiment of the present disclosure, the copolyester is made in two main stages. The first stage reacts the starting materials to form monomers and / or oligomers. If the starting materials entering the first stage include acid end groups, such as TPA or isophthalic acid, the first stage is called esterification. The esterification stage can be a single step or can be divided into multiple steps. The second stage further reacts the monomers and / or oligomers to form the final copolyester product. The second stage is generally referred to as the polycondensation stage. The polycondensation stage can be a single step or can be divided into a pre-polycondensation (or prepolymerization) step and a final (or finishing) polycondensation step.

[0068] Figure 1 A process flow diagram showing the manufacture of polyester or copolyester such as PETG according to various embodiments of the present disclosure is shown. Although the flow diagram ( Figure 1 ) show the reaction zones as separate vessels, which are typically continuous stirred tank reactors (CSTRs), but these vessels may be integrated units with multiple esterification zones (with appropriate partitioning and controls). Likewise, although the reaction zones are shown as separate vessels, which are typically wiped film or thin film type CSTRs, these vessels may be combined in one or more integrated units with multiple polycondensation zones (with appropriate partitioning and controls). Various other types of esterification and polycondensation reactors and reactor arrangements are known in the art and may be adapted for use in accordance with the present disclosure.

[0069] refer to Figure 1In one embodiment, a paste consisting of a 2:1 molar ratio of EG and TPA with recycled copolyester and / or polyester is fed to the location marked as the paste tank. Additional EG is fed to the first reaction zone or reactor 1 and based on the target final composition of the copolyester, other glycols such as CHDM, TMCD, NPG and DEG may also be fed to the first reaction zone at the same location, and optionally, additional recycled materials may be added. In one embodiment, these raw materials may be added separately and / or directly to the first reaction zone. In some embodiments, the recycled copolyester and / or polyester is fed to at least one of the following locations: a paste tank, zone #1, zone #2, or a refining zone. In some embodiments, the recycled copolyester and / or polyester is fed to one or more of the following locations: a paste tank, zone #1, zone #2, or a refining zone.

[0070] The reaction mixture is heated in the first reaction zone by means of a recirculation loop including a heat exchanger. Esterification occurs in the first reaction zone to form a first esterified product comprising copolyester monomers, oligomers, or both and unreacted TPA, EG, and other glycols, such as CHDM, TMCD, NPG, or DEG. The reaction product of the first reaction zone is then transferred to the second reaction zone. Further esterification occurs in the second reaction zone to form a second esterified product comprising additional copolyester monomers, oligomers, or both.

[0071] In some embodiments, the average chain length of the monomers and / or oligomers exiting the esterification stage may be less than 25, 1 to 20, or 5 to 15.

[0072] In one embodiment, the second reaction zone is optional.In some embodiments, the product is passed from the first reaction zone to the third reaction zone.

[0073] The reaction product of the second reaction zone is then sent to the third reaction zone. In some embodiments, polycondensation occurs in the third reaction zone, optionally in the presence of a polycondensation catalyst, to form a prepolymerization product comprising a copolyester oligomer. In some embodiments, polycondensation occurs in the third reaction zone without the need for a polycondensation catalyst, to form a prepolymerization product comprising a copolyester oligomer. In some embodiments, the catalyst residue remaining in the copolyester and the polyester is recovered and is enough to serve as a polycondensation catalyst. In some embodiments, the third reaction zone is converted into an oligomer with an average chain length of 2 to 40, 5 to 35, or 10 to 30 by the monomer leaving the esterification stage.

[0074] The prepolymer product is then conveyed to one or more reaction zones or refining zones. Additional polycondensation occurs in the refining zone, optionally in the presence of a polycondensation catalyst, to form a copolyester having a desired average chain length or IV. The copolyester is then removed from the refining zone for subsequent processing, such as forming into pellets by an extruder connected to an underwater pelletizer.

[0075] In one embodiment, the temperature in the paste tank is 120-180°C.

[0076] In one embodiment, the temperature in the glycolysis and transesterification zone is 200-300°C.

[0077] In one embodiment, the reacting step is performed at a melt temperature of at least 253° C., at least 255° C., or at least 257° C. In one embodiment, additionally or alternatively, the reacting step is performed at a melt temperature of no greater than 290° C., no greater than 285° C., no greater than 280° C., no greater than 275° C., no greater than 270° C., or no greater than 265° C. In various embodiments, the reacting step is performed at a melt temperature of 250 to 270° C., or 257 to 265° C.

[0078] In one embodiment, the reacting step is conducted at a pressure of 25 to 40 psi, or 30 to 40 psig.

[0079] In one embodiment, the esterification step is performed at a melt temperature of at least 253° C., at least 255° C., or at least 257° C. In one embodiment, additionally or alternatively, the esterification step is performed at a melt temperature of no greater than 290° C., no greater than 285° C., no greater than 280° C., no greater than 275° C., no greater than 270° C., or no greater than 265° C. In various embodiments, the esterification step is performed at a melt temperature of 250 to 270° C., or 257 to 265° C.

[0080] In one embodiment, the esterification step (d) is conducted at a pressure of 8 to 20 psig.

[0081] In one embodiment, the average residence time of the reactants in the reaction step is 2 hours or less, 1.75 hours or less, 1.5 hours or less, 1.25 hours or less, 1 hour or less, or 0.75 hour or less. In various embodiments, the average residence time of the reactants in the reaction step is 30 to 40 minutes.

[0082] In one embodiment, the average residence time of the reactants in the esterification step is 2 hours or less, 1.75 hours or less, 1.5 hours or less, 1.25 hours or less, 1 hour or less, or 0.75 hours or less. In various embodiments, the average residence time of the reactants in the esterification step (d) is 30 to 40 minutes.

[0083] In various embodiments, the total molar ratio of EG:TPA introduced into the process is from 2.3:1 to 3.0:1.

[0084] In various embodiments, the total molar ratio of EG:TPA introduced into the process is from 2.3:1 to 2.71:1.

[0085] The temperature, pressure and average residence time of the reaction step in the first reaction zone are those described above.

[0086] In various embodiments, the reacting step in the first reaction zone is conducted at a melt temperature of 250 to 270°C and a pressure of 25 to 40 psi.

[0087] In various embodiments, the reacting step in the first reaction zone is conducted at a melt temperature of 257 to 265°C and a pressure of 30 to 40 psi.

[0088] The temperature, pressure and average residence time for the esterification step in the second reaction zone are those described above.

[0089] In various embodiments, the esterification step in the second reaction zone is conducted at a melt temperature of 250 to 270°C and a pressure of 8 to 20 psi.

[0090] In various embodiments, the esterification step in the second reaction zone is conducted at a melt temperature of 257 to 265°C and a pressure of 8 to 20 psi.

[0091] The polycondensation catalysts that can be used for the method of the present disclosure are not particularly limited. Examples of such catalysts include titanium-based compounds, antimony-based compounds, and germanium-based compounds. Titanium catalysts are very efficient and provide high polycondensation rates at low catalyst levels. The polycondensation catalysts can be added during the esterification stage or the polycondensation stage. In one embodiment, they are added to the first reaction zone along with the feed material. In one embodiment, the catalyst is added in the range of 1 to 500 ppm based on the weight of the copolyester. In one embodiment, in the case of titanium, the catalyst can be added in the range of 1 to 50 ppm based on the weight of the copolyester.

[0092] In one embodiment, catalyst selection is influenced by the catalyst derived from the recycled feed. Specific catalytic advantages are achieved by the combination of the catalyst from the feed and the catalyst added to the first reaction zone and the second reaction zone. Catalysts that may be derived from rPET include Sb and Li / Al. Catalysts from rPETG can be Ti, Co, Ge and Sb. Catalysts from rPETM and rPCTM include Co.

[0093] In some embodiments, phosphorus compounds are usually added with catalysts to improve thermal stability. Phosphorus compounds that can be used as heat stabilizers include phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid, phosphous acid and various esters and salts thereof. The ester can be an alkyl, branched alkyl, substituted alkyl, difunctional alkyl, alkyl ether, aryl and substituted aryl. In some embodiments, suitable heat stabilizers include triphenyl phosphate Merpol A. In one embodiment, phosphorus is added in the range of 0 to 100 ppm based on the weight of the copolyester.

[0094] In various embodiments, one or more other additives may be added to the starting materials, copolyesters and / or copolyester monomers / oligomers at one or more locations within the process. In various embodiments, suitable additives may include, for example, trifunctional or tetrafunctional comonomers such as trimellitic anhydride, trimethylolpropane, pyromellitic dianhydride, pentaerythritol or other polyacids or polyols; crosslinking agents or other branching agents; colorants; toners; pigments; carbon black; glass fibers; fillers; impact modifiers; antioxidants; UV absorber compounds; oxygen scavenging compounds; etc.

[0095] The processes according to the present disclosure are particularly suitable for use on an industrial scale. For example, in one embodiment, they can be implemented on a commercial production line capable of operating at a rate of 500 to 30,000 lbs / hr polymer.

[0096] In another aspect, the present disclosure relates to copolyesters made by the process of the present disclosure.

[0097] Still further according to the above method, the new polyester product may contain glycol units of ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol, wherein the 1,4-cyclohexanedimethanol units constitute up to about 25 mole % of the total glycol units and diethylene glycol constitutes up to 15 mole % of the total glycol units. In this case, the 1,4-cyclohexanedimethanol units and diethylene glycol units may be added directly to a portion of the ethylene glycol component in the first reaction mixture or in a portion of a post-consumer poly(ethylene terephthalate) or glycol-modified poly(ethylene terephthalate) flake material.

[0098] In various embodiments, the copolyester comprises:

[0099] (a) a diacid component comprising 60 to 100 mole % of residues of terephthalic acid, isophthalic acid, or mixtures thereof; and

[0100] (b) a diol component comprising 0-96.5 mol % of residues of ethylene glycol and 3.5 to 100 mol % of residues of 1,4-cyclohexanedimethanol,

[0101] The diacid component is calculated based on 100 mol % of the total diacid residues in the copolyester, and the diol component is calculated based on 100 mol % of the total diol residues in the copolyester.

[0102] In various embodiments, the copolyester comprises:

[0103] (a) a diacid component comprising from 90 to 100 mole percent of residues of terephthalic acid; and

[0104] (b) a diol component comprising 50 to 96.5 mol % of residues of ethylene glycol and 3.5 to 50 mol % of residues of 1,4-cyclohexanedimethanol,

[0105] The diacid component is calculated based on 100 mol % of the total diacid residues in the copolyester, and the diol component is calculated based on 100 mol % of the total diol residues in the copolyester.

[0106] In various embodiments, the copolyester comprises:

[0107] (a) a diacid component comprising from 90 to 100 mole percent of residues of terephthalic acid; and

[0108] (b) a diol component comprising 0 to 50 mol % of residues of ethylene glycol and 50 to 100 mol % of residues of 1,4-cyclohexanedimethanol,

[0109] The diacid component is calculated based on 100 mol % of the total diacid residues in the copolyester, and the diol component is calculated based on 100 mol % of the total diol residues in the copolyester.

[0110] In various embodiments, the copolyester comprises:

[0111] (a) a diacid component comprising from 60 to 100 mole % of residues of terephthalic acid; and

[0112] (b) a diol component comprising 65 to 85 mole % of residues of ethylene glycol and 25 to 35 mole % of residues of 1,4-cyclohexanedimethanol,

[0113] The diacid component is calculated based on 100 mol % of the total diacid residues in the copolyester, and the diol component is calculated based on 100 mol % of the total diol residues in the copolyester.

[0114] In various embodiments, the copolyester has an intrinsic viscosity of 0.4 to 1.5 dL / g, or 0.5 to 1.2 dL / g, or 0.6 to 0.9 dL / g.

[0115] In various other embodiments, the copolyester comprises:

[0116] (a) a diacid component comprising 100 mole % of residues of terephthalic acid, isophthalic acid, or mixtures thereof;

[0117] (b) a diol component comprising 0 to 96.5 mole % of residues of ethylene glycol, 3.5 to 100 mole % of residues of 1,4-cyclohexanedimethanol, and 0 to 0.4 mole % of residues of trimellitic anhydride; and

[0118] wherein the copolyester has an intrinsic viscosity (IV) of 0.4 to 1.5 dL / g,

[0119] wherein all weight percentages are based on the total weight of the copolyester; and

[0120] The diacid component is calculated based on 100 mol % of the total diacid residues in the copolyester, and the diol component is calculated based on 100 mol % of the total diol residues in the copolyester.

[0121] In one embodiment, the present disclosure includes an article of manufacture or shaped article comprising a shrink film of any shrink film embodiment of the present disclosure. In another embodiment, the present disclosure includes an article of manufacture or shaped article comprising an oriented film of any oriented film embodiment of the present disclosure.

[0122] In certain embodiments, the present disclosure includes, but is not limited to, shrink films applied to containers, plastic bottles, glass bottles, packaging, battery packs, hot-fill containers, and / or industrial articles, or other applications. In one embodiment, the present disclosure includes, but is not limited to, oriented films applied to containers, packaging, plastic bottles, glass bottles, photosensitive substrates such as paper, battery packs, hot-fill containers, and / or industrial articles, or other applications.

[0123] In certain embodiments of the present disclosure, the shrink film of the present disclosure can be formed into a label or sleeve. The label or sleeve can then be applied to a finished product, such as a container wall, a battery pack, or applied to a sheet or film.

[0124] The oriented films or shrink films of the present disclosure can be applied to shaped articles, such as sheets, films, tubes, bottles, and are commonly used in various packaging applications. For example, films and sheets made from polymers such as polyolefins, polystyrene, poly(vinyl chloride), polyesters, polylactic acid (PLA), etc. are often used to make shrink labels for plastic beverage or food containers. For example, the shrink films of the present disclosure can be used in many packaging applications, wherein the shrink films applied to shaped articles exhibit properties such as good printability, high opacity, higher shrink force, good texture, and good stiffness.

[0125] The combination of improved shrink properties and improved toughness should provide new commercial options including, but not limited to, shrink films for containers, plastic bottles, glass bottles, packaging, battery packs, hot fill containers and / or industrial articles or other applications.

[0126] Additionally, the materials of the present disclosure can be extruded into sheets, and the sheets can be further thermoformed into three-dimensional articles.The materials of the present disclosure can be converted into molded articles, films, shrinkable films, oriented films, blown articles, and blown film articles.

[0127] The present disclosure includes and explicitly contemplates and discloses any and all combinations of the embodiments, features, characteristics, parameters and / or ranges mentioned herein. That is, the subject matter of the present disclosure can be defined by any combination of the embodiments, features, characteristics, parameters and / or ranges mentioned herein.

[0128] Any process / method, apparatus, compound, composition, embodiment or component of the present disclosure may be modified by the transitional terms "comprising," "consisting essentially of," or "consisting of," or variations of these terms.

[0129] As used herein, the indefinite articles "a" and "an" refer to one or more, unless the context clearly indicates otherwise. Similarly, singular forms of nouns include their plural forms and vice versa, unless the context clearly indicates otherwise.

[0130] Although attempts have been made to make it precise, the numerical values ​​and ranges described herein should be considered approximate unless the context otherwise indicates. These values ​​and ranges may deviate from their specified numbers depending on the desired properties that the present disclosure seeks to obtain and the changes caused by the standard deviations present in the measurement technology. In addition, the ranges described herein are intended and explicitly contemplated to include all subranges and numerical values ​​within the specified ranges. For example, the range 50 to 100 is intended to include all numerical values ​​within the range, including subranges such as 60 to 90, 70 to 80, etc.

[0131] Any two numerical values ​​of the same property or parameter reported in the examples may define a range. These numerical values ​​may be rounded to the nearest thousandth, hundredth, tenth, integer, ten, hundredth or thousand to define the range.

[0132] The contents of all documents cited herein, including patents and non-patent documents, are incorporated herein by reference in their entirety. If any incorporated subject matter contradicts any disclosure herein, the disclosure herein shall take precedence over the incorporated content.

[0133] The present disclosure may be further illustrated by the following examples, but it should be understood that these examples are included for illustrative purposes only and are not intended to limit the scope of the present disclosure. Example

[0134] Laboratory scale process results:

[0135] General procedure: A mixture of 53.16 g of PTA, 62.21 g of EG, 2.97 g of DEG, 11.52 g of CHDM, and 18.86 g of rPET was placed in a 500 ml flask equipped with a nitrogen inlet, a metal stirrer, and a short-path distillation column. In addition, 0.14 ml of Ti catalyst solution (target 16 ppm Ti) and 1 ml of Mn solution (target 45 ppm Mn) were added to the flask. The flask was placed in a Wood's metal bath heated to 200°C. The stirring speed was set to 200 RPM at the beginning of the experiment. The contents of the flask were heated at 200°C for 60 minutes, and then the temperature was gradually increased to 250°C over 300 minutes. The reaction mixture was then heated to 270°C for 20 minutes, while stirring was slowed to 100 rpm and vacuum was gradually applied to 0.4 Torr. The temperature was then increased to 278°C over 20 minutes and stirring was reduced to 60 rpm, and the mixture was kept under these conditions for 120 minutes. After this hold, the mixture was returned to atmospheric pressure and heating was stopped. The polymer was then removed from the flask for analysis. Example 1 was performed with rPET 100% replacing TPA. Example 2 was performed with rPET 20% replacing TPA.

[0136] In one aspect of the present disclosure, given a reasonably constant supply of rPET, Figure 2 The predicted amounts of Sb and other residual catalysts and additives are shown in . In some embodiments, Figure 2 This shows that the amount of antimony that must be added to the system can be balanced based on the amount of rPET fed into the process. For example, if 100 ppm of Sb is desired in the final product, 60% rPET can be fed into the process or 20% rPET can be fed and 60 ppm of Sb added to the system.

[0137] Laboratory resin characterization:

[0138]

[0139]

[0140] The resins made in both cases were similar in all key performance criteria. The two materials had similar color, IV and composition, regardless of the amount of rPET added.

[0141] Pilot plant process results:

[0142] Resin samples (A1 and A2) were made by adding 7.3 wt% recycled PET by weight to a reactor containing 45.7 wt% ethylene glycol, 0.7 wt% diethylene glycol, 9.8 wt% cyclohexanedimethanol, and 36.4 wt% terephthalic acid. Ti catalyst was added at 30 ppm. The glycol to acid ratio was 3.3, with ethylene glycol and cyclohexanedimethanol used to make up the excess. The reaction mixture was maintained at 250-255°C and 25-30 psig for 3-3.5 hours. Phosphorus was added at 21 ppm, and the reaction mixture was then heated to 270°C and stirred under vacuum until the target melt viscosity was reached.

[0143] The control resin sample (B) was made using the same method, except that rPET or DEG were not added to the reaction mixture and 50 ppm of Ti catalyst was used. 44.1 wt % ethylene glycol, 10.5 wt % cyclohexanedimethanol and 45.5 wt % terephthalic acid were loaded into the reactor. The ratio of glycol to acid was 2.9, with ethylene glycol and cyclohexanedimethanol used to make up the excess. The CHDM excess was the same as in the previous example, while the EG excess was reduced.

[0144] The characterization of the resins is described in the table below.

[0145] Pilot Plant Resin Characterization:

[0146]

[0147]

[0148] Resin Examples A1 and A2 were combined to make Resin A. Resins A and B were dried in a dehumidified dryer at 60°C for 4-6 hours. Films having a thickness of 10 mils (250 microns) were then extruded using a 2.5" Davis and Standard extruder. Once extruded, the films were cut and stretched on a Bruckner Karo 4 tenter frame to a final thickness of 50 microns. The films were stretched at a ratio of 5:1 with a stretch rate of 100% / sec and a stretch temperature of 5-15°C above the Tg of the extruded film. Characterization of the shrinkable films made in this manner is described in the table below.

[0149] Examples A and B: Shrinkable films made from resin compositions made from rPET

[0150]

[0151] Resins A and B have very similar compositions, IVs, and colors. Shrinkable films made with these resins also have very similar properties. These results demonstrate that incorporating rPET into the resin manufacturing process does not affect the final properties of the resin or articles made from the resin.

[0152] Commercial scale process:

[0153] Resin samples were also produced on a commercial manufacturing facility to demonstrate the utility of the present invention.

[0154] In a commercial scale process, 5% recycled PET is added to a slurry tank along with terephthalic acid and ethylene glycol. The slurry tank is stirred for more than 30 minutes to achieve thorough mixing. This slurry is then added to reaction zone 1 along with the catalyst, additional ethylene glycol, diethylene glycol, and cyclohexanediol. This mixture is reacted at a pressure of 35+psig at above 235°C for at least 1 hour to simultaneously depolymerize the PET and react the monomers. The monomers and oligomers from reaction zone 1 are then conveyed to reaction zone 2 where they are further reacted while separating out additional glycols, but maintaining the reaction temperature. The material enters reaction zone 3 to be refined at higher temperatures and deeper vacuum conditions. Characterization of the final product (Example C) is shown in the table below, compared to another copolyester resin (Example D) of the same composition that was also made in a commercial process without the addition of rPET.

[0155] Commercial Process Resin Characterization:

[0156]

[0157]

[0158] Resins C and D were dried in a dehumidified dryer at 60°C for 4-6 hours. Films having a thickness of 10 mils (250 microns) were then extruded using a 2.5" Davis and Standard extruder. Once extruded, the films were cut and stretched on a Bruckner Karo 4 tenter frame to a final thickness of 50 microns. The films were stretched at a ratio of 5:1 with a stretch rate of 100% / sec and a stretch temperature of 5-15°C above the Tg of the extruded film. Characterization of the shrinkable films made in this manner is described in the table below.

[0159] Examples C and D: Shrinkable films made from resin compositions made with rPET

[0160]

[0161] Resins C and D have very similar compositions, IVs, and colors. Shrinkable films made with these resins also have very similar properties. These results demonstrate that incorporating rPET into the resin manufacturing process does not affect the final properties of the resin or articles made from the resin.

[0162] The disclosure has been described in detail with particular reference to specific embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the disclosure.

Claims

1. A method for producing a polyester composition from recycled polyester, comprising: (a) introducing terephthalic acid (TPA); and ethylene glycol (EG); and recycled polyester comprising one or more of recycled PET, recycled PETG, recycled PCT, recycled PCTA, recycled PCTG, recycled PCTM or recycled PETM into a paste tank to form a slurry, which is stirred and heated at a temperature of up to 150° C.; (b) transferring the paste tank slurry to the first reaction zone; (c) introducing at least one additional diol comprising 1,4-cyclohexanedimethanol (CHDM), neopentyl glycol (NPG), 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD), diethylene glycol (DEG), or isosorbide into the first reaction zone in the presence of an esterification catalyst to a total diol:TPA molar ratio of 1:1 to 4:1; (d) reacting the TPA and EG and the recycled polyester with the at least one additional diol in the first reaction zone at a melt temperature of at least 175° C. to form an esterification product comprising oligomers and unreacted TPA, EG, and the at least one additional diol; (g) transferring the resulting esterification product from the reaction zone to a third reaction zone; (h) polycondensing the resulting esterification product in a third reaction zone to form a polymerized product comprising a polyester, The esterification catalyst comprises one or more of Mn, Ti, Zn, Co, Ge or Al, and the esterification catalyst is 1 to 500 ppm.

2. The method according to claim 1, comprising: (a) introducing terephthalic acid (TPA); and ethylene glycol (EG); and recycled polyester comprising one or more of recycled PET, recycled PETG, recycled PCT, recycled PCTA, recycled PCTG, recycled PCTM or recycled PETM into a paste tank to form a slurry, which is stirred and heated at a temperature of up to 150° C.; (b) transferring the paste tank slurry to the first reaction zone; (c) introducing into the first reaction zone at least one additional diol including 1,4-cyclohexanedimethanol (CHDM), neopentyl glycol (NPG), 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD), diethylene glycol (DEG) or isosorbide in the presence of an esterification catalyst and a stabilizer, and adding additional recycled polyester including one or more of recycled PET, recycled PETG, recycled PCT, recycled PCTA, recycled PCTG, recycled PCTM or recycled PETM; and adding additional terephthalic acid (TPA); and ethylene glycol (EG) to a total diol:TPA molar ratio of 1:1 to 4:1; (d) reacting the TPA and EG and the recycled polyester with the at least one additional diol in the first reaction zone at a melt temperature of at least 175° C. to form an esterification product comprising oligomers and unreacted TPA, EG, and the at least one additional diol; (e) transferring the esterification product from the first reaction zone to a second reaction zone; (f) further reacting the esterification product from the first reaction zone in the presence of an esterification catalyst and a stabilizer at a melt temperature of at least 200° C. in the second reaction zone and adding additional diols comprising one or more of CHDM, NPG, TMCD, DEG or isosorbide and / or additional recycled polyester comprising one or more of recycled PET, recycled PETG, recycled PCT, recycled PCTA, recycled PCTG, recycled PCTM or recycled PETM to form an esterification product comprising polyester oligomers; (g) transferring the resulting esterified product from the one or more reaction zones to a third reaction zone; (h) polycondensing the resulting esterification product in a third reaction zone in the presence of a polycondensation catalyst and a stabilizer and adding additional recycled polyester comprising one or more of recycled PET, recycled PETG, recycled PCT, recycled PCTA, recycled PCTG, recycled PCTM or recycled PETM to form a polymer product comprising polyester, wherein the esterification catalyst comprises one or more of Mn, Ti, Zn, Co, Ge or Al, and the esterification catalyst is 1 to 500 ppm, wherein the polycondensation catalyst comprises one or more of Sn, Sb, Ti, Li / Al, Al, Ge, Pb, Zn, Co, Bi, Cd, Ca or Ni, and the polycondensation catalyst is 1 to 500 ppm, and The stabilizer is selected from phosphoric acid, phosphorous acid, phosphonic acid, phosphinic acid, phosphous acid and various esters and salts thereof, and the amount of the stabilizer used is such that the phosphorus content is 10 to 100 ppm.

3. The method of claim 1, wherein step (d) is performed at a melt temperature of at least 240°C; or wherein step (d) is performed at a melt temperature of at least 250°C and a pressure of up to 30 psig.

4. The method of claim 1, wherein step (f) is performed at a melt temperature of at least 240°C.

5. The method of claim 1, wherein the polyester has an intrinsic viscosity of 0.4 to 1.2 dL / g.

6. The method of claim 1 wherein the polyester comprises 19 to 96.5 mole percent ethylene glycol and 3.5 to 81 mole percent 1,4-cyclohexanedimethanol based on the total diol residues in the polyester.

7. The method of claim 1, wherein the polyester comprises 50 to 90 mole % of ethylene glycol and 10 to 50 mole % of 1,4-cyclohexanedimethanol, based on the total diol residues in the polyester.

8. The method of claim 1 wherein the polyester comprises 65 to 75 mole % ethylene glycol and 25 to 35 mole % 1,4-cyclohexanedimethanol based on the total diol residues in the polyester.

9. The method of claim 1, wherein the polyester comprises 60 to 70 mole % ethylene glycol and 20 to 25 mole % 1,4-cyclohexanedimethanol and 10-15% diethylene glycol based on the total diol residues in the polyester.

10. The method of claim 1 wherein the polyester comprises 75 to 93 mole % ethylene glycol and 5-15 mole % neopentyl glycol and 2-10 % diethylene glycol based on the total glycol residues in the polyester.

11. The method of claim 1 wherein the polyester comprises 65 to 92 mole % ethylene glycol, 1-10 mole % 1,4-cyclohexanedimethanol, 5-15 mole % neopentyl glycol, and 2-10% diethylene glycol based on the total diol residues in the polyester.

12. The method of claim 1, wherein the polyester comprises: (a) a diacid component comprising 90 to 100 mole percent terephthalic acid; and (b) a diol component comprising 65 to 75 mole % of ethylene glycol and 25 to 35 mole % of residues of 1,4-cyclohexanedimethanol, The diacid component is calculated based on 100 mol% of the total diacid residues in the polyester, and the diol component is calculated based on 100 mol% of the total diol residues in the polyester.

13. The method of claim 1, wherein the polyester comprises 50 to 99.99 mol% of 1,4-cyclohexanedimethanol, 0.01 to 50 mol% of ethylene glycol, and 70 to 100 mol% of terephthalic acid, based on a total of 100 mol% of acid residues and a total of 100 mol% of diol residues.

14. The method of claim 1, wherein the polyester comprises 80 to 99.99 mol% of 1,4-cyclohexanedimethanol, 0.01 to 20 mol% of ethylene glycol, and 70 to 100 mol% of terephthalic acid, based on a total of 100 mol% of acid residues and a total of 100 mol% of diol residues.

15. The method of claim 1 wherein the polyester comprises 90 to 99.99 mole % of residues of 1,4-cyclohexanedimethanol, 0.01 to 10 mole % of residues of ethylene glycol, and 70 to 100 mole % of residues of terephthalic acid, based on a total of 100 mole % of acid residues and a total of 100 mole % of diol residues.

16. The method of claim 1 wherein the polyester comprises 95 to 99.99 mole % residues of 1,4-cyclohexanedimethanol, 0.01 to 10 mole % residues of ethylene glycol, 90 to 100 mole % residues of terephthalic acid, and 0.01 to 10 mole % residues of isophthalic acid, based on a total of 100 mole % acid residues and a total of 100 mole % diol residues.

17. The method of claim 1 wherein the polyester comprises from 20 mol% to less than 50 mol% of residues of 1,4-cyclohexanedimethanol, from greater than 50 mol% to 80 mol% of residues of ethylene glycol, and from 70 mol% to 100 mol% of residues of terephthalic acid, based on a total of 100 mol% of acid residues and a total of 100 mol% of diol residues.

18. The method of claim 1, wherein the polyester comprises (a) a dicarboxylic acid component comprising: (i) 70 to 100 mole % of terephthalic acid residues, and (ii) 0 to 30 mol % of aromatic and / or aliphatic dicarboxylic acid residues having up to 20 carbon atoms; and (b) a diol component comprising: (i) 0 to 40 mol % 2,2-dimethylpropane-1,3-diol (neopentyl glycol or NPG) residues; (ii) 0 to 100 mol % 1,4-cyclohexanedimethanol (CHDM) residues; (iii) 0 to 45 mol% 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) residues; (iv) 0 to 40 mol % diethylene glycol (DEG) residues, whether or not formed in situ; The balance of the diol component comprises: (v) residues of ethylene glycol, and (vi) optionally, 0 to 10 mole % of the residue of at least one other modifying diol; wherein the total mole % of the dicarboxylic acid components is 100 mole %, and wherein the total mole % of the diol components is 100 mole %.

19. The method of claim 18, wherein the polyester comprises at least 90 mol% terephthalic acid and 59 to 77.5 mol% ethylene glycol, 15 to 28 mol% 1,4-cyclohexanedimethanol (CHDM), and 7.5 to 13 mol% diethylene glycol (DEG); wherein the dicarboxylic acid component is based on 100 mol% and the diol component is based on 100 mol%.

20. The process according to the preceding claim 1, wherein the amount of recycled polyester added to the process is 5-100% based on the amount of TPA required.

21. The method according to the preceding claim 1, wherein the method further comprises adding an additive by adding recycled polyester, wherein the additive is a component of the recycled polyester.

22. The method according to the preceding claim 1, wherein the method further comprises adding additives by adding recycled polyester, wherein the additives are Sb, Ti, Co, Mn, Li, Al, P.

23. The method of claim 1, wherein the polyester has an intrinsic viscosity of 0.5 to 0.9 dL / g.

24. The method according to the preceding claim 1, wherein the method further comprises adding a catalyst by adding recycled polyester, wherein the catalyst is a component of the recycled polyester.

25. The method according to the preceding claim 1, wherein the method further comprises adding a catalyst by adding recycled polyester, wherein the catalyst is Sb, Ti, Co, Mn, Li, Al, P.

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