United States Patent (19) 11 4,259,478 Jackson, Jr. et al. 45) Mar. 31, 1981

(54) PROCESS FOR PREPARING HIGH Attorney, Agent, or Firm-John F. Stevens; Daniel B. MOLECULAR WEIGHT COPOLYESTERS Reece III (75) Inventors: Winston J. Jackson, Jr.; Herbert F. 57 ABSTRACT Kuhfuss, both of Kingsport, Tenn. Disclosed is a process for preparing linear, high molecu 73 Assignee: Eastman Kodak Company, lar weight copolyesters from either (A) or Rochester, N.Y. copolyesters, the acid component of which consists of at least 70 mole percent terephthalic acid and the diol 21 Appl. No.: 103,805 component of which consists of at least 70 mole percent 22 Filed: Dec. 14, 1979 ethylene glycolor (B) copolyesters, the acid component of which consists of at least 70 mole percent tereph 51) Int. Cl...... C08G 63/18 thalic acid and the diol component of which consists of 52 U.S. C...... 528/307; 260/2.3; at least 70 mole percent of a mixture of 525/437; 525/444; 528/272; 528/309 and 1,4-cyclohexanedimethanol in a mole ratio of from 58) Field of Search ...... 528/272,307, 309; 20:80 to 97:3, the process comprising heating the poly w 260/2.3; 525/437, 444 mer in the presence of 1,4-cyclohexanedimethanol to (56) References Cited glycolize the polymer, distilling out ethylene glycol from the glycolysis mixture, and polycondensing the U.S. PATENT DOCUMENTS glycolysis mixture to form a copolyester of which at 3,222,299 12/1965 McDowell ...... 260/2.3 least a portion of ethylene glycol units are replaced by 3,344,09 9/1967. Russin et al...... 260/2.3 1,4-cyclohexanedimethanol units. The process provides 3,378,402 4/1968 Wiener ...... 528/307 X a fast polymerization rate and the polymers so produced 3,427,267 2/1969 Stieger et al...... 260/22 can be used in the manufacture of plastics, fibers, films 4,078, 143 3/1978 Malik et al...... 260/2.3 and other shaped objects having good physical proper 4,079,047 3/1978 Jackson ...... 528/309 X ties. 4,138,374 2/1979 Currie ...... 260/2.3 Primary Examiner-Lucille M. Phynes 10 Claims, No Drawings

M 4,259,478 1. 2 PROCESS FOR PREPARING HIGH MOLECULAR DETAILED DESCRIPTION OF THE WEIGHT COPOLYESTERS INVENTION According to the present invention, a process is pro BACKGROUND OF THE INVENTION 5 vided for preparing linear, high molecular weight co 1. Field of the Invention polyesters from either. This invention relates to a process for utilizing poly (A) polyesters or copolyesters, the acid component of ethylene terephthalate, especially scrap polyethylene which consists of at least 70 mole percent tereph terephthalate in the production of linear, high molecu thalic acid and the diol component of which con lar weight copolyesters. 10 sists of at least 70 mole percent ethylene glycol, or The growing demand for polyethylene terephthalate (B) copolyesters, the acid component of which con disposable containers such as beverage bottles has cre sists of at least 70 mole percent terephthalic acid ated a need to develop uses for scrap polyethylene tere and the diol component of which consists of at least phthalate. The present invention provides a process for 70 mole percent of a mixture of ethylene glycol and utilizing polyethylene terephthalate as a reactive inter 15 1,4-cyclohexanedimethanol in a ratio of from 20:80 mediate in the production of copolyesters useful in the to 97:3. manufacture of such products as fibers, films, and other In the first step of the process, the polymer is heated shaped objects. to a temperature of from about 200 C. to about 290 C., 2. Description of the Prior Art in the presence of from about 3 mole percent up to an Numerous patents, disclose processes for utilizing 20 amount equivalent to the mole percent of ethylene gly scrap polyesters in polymer production such as U.S. col in the polymer, of 1,4-cyclohexanedimethanol to Pat. Nos. 3,222,999, 3,344,091, 4,078,143 and 4,138,374. glycolize the polymer. Next, at least a portion of the In U.S. Pat. No. 3,222,299 it is stated that reclaimed ethylene glycol is removed from the glycolysis mixture monomer, obtained by heating waste polymer with by distillation. Normally, the mixture is heated to a 25 temperature of about 275 C. for about 30 to 60 minutes glycol, may be injected into the polymerization system to accomplish this distillation. In a subsequent step, the but must be kept below a level of about 20% of the total glycolysis mixture is polycondensed to form a copolyes monomer if the polymer produced is to have satisfac ter of which at least a portion of the ethylene glycol tory properties. When amounts of recovered monomer units are replaced by 1,4-cyclohexanedimethanol units higher than about 20% are injected, it is found that the 30 and the inherent viscosity has reached at least 0.4. rate of polymerization of the mixture is reduced to such Polyethylene terephthalate and/or polyethylene te an extent that the output of the equipment must be cut rephthalate/cyclohexanedimethanol copolyesters with back to a prohibitively low level. In the present process, an I.V. of at least 0.2 can be used to prepare the copoly 100% scrap can be utilized with no loss in of this invention. Preferably, scrap polyethylene properties or polymerization rate. In fact, the polymeri 35 terephthalate with an I.V. of 0.3-0.6 is used. The acid zation rate is faster than the rate for the preparation of portion of the polyethylene terephthalate or polyethyl the same copolyesters from , ene terephthalate/cyclohexanedimethanol copolyester ethylene glycol, and 1,4-cyclohexanedimethanol. used in this invention may be modified with up to 30 SUMMARY OF THE INVENTION mole % of other aliphatic, alicyclic or aromatic dicar boxylic acids such as isophthalic acid, 2,6-naph- . The present invention provides a process for prepar thalenedicarboxylic acid, cis or trans-1,4-cyclohex ing linear, high molecular weight copolyesters from anedicarboxylic acid, monochloroterephthalic acid, either (A) polyesters or copolyesters, the acid compo dichloroterephthalic acid, methylterephthalic acid, nent of which consists of at least 70 mole percent ter dimethylterephthalic acid, 4,4'-diphenyldicarboxylic ephthalic acid and the diol component of which consists 45 acid, adipic acid, azelaic acid, and dodecanedicarboxy of at least 70 mole percent ethylene glycol or (B) co lic acid. No. additional modifier is preferred. polyesters, the acid component of which consists of at The diol portion of the polyethylene terephthalate or least 70 mole percent terephthalic acid and the diol polyethylene terephthalate/cyclohexanedimethanol component of which consists of at least 70 mole percent copolyester used in this invention may be modified with of a mixture of ethylene glycol and 1,4-cyclohex 50 up to 30 mole % of an aliphatic glycol such as 1,4- anedimethanol in a ratio of from 20:80 to 97:3, the pro butanediol, 1,5-pentanediol, 1,6-hexanediol, or 2,2- cess comprising dimethyl-1,3-propanediol. No additional modifier is (1) heating the polymer to a temperature of from preferred. about 200 C. to about 290° C. in the presence of The copolymers of this invention are made by glycol : about 3 mole percent to an amount equivalent to 55 ysis of polyethylene terephthalate of polyethylene te the mole percent of ethylene glycol of 1,4- rephthalate/cyclohexanedimethanol copolyesters (pref cyclohexanedimethanol to glycolize the polymer, erably scrap polyester) with 1,4-cyclohexanedime (2) distilling out at least a portion of the ethylene thanol at about 275 C. The glycolysis can also be car glycol from the glycolysis mixture, and ried out on mixtures of polyethylene terephthalate and (3) polycondensing the glycolysis mixture to form a copolyesters of polyethylene terephthalate modified copolyester of which at least a portion of ethylene with about 3 to 80 mole %. 1,4-cyclohexanedimethanol. glycol units are replaced by 1,4-cyclohexanedime A glycolysis temperature lower than 275 C. can be thanol units and the inherent viscosity is at least used, but the temperature must be above the melting 0.4. point of the polyester so the polyester will be molten. The process provides a fast polymerization rate and the 65 Glycolysis temperatures as low as 200 C. can be used polymers so produced can be used in the manufacture of with the lower melting copolyesters under these condi plastics, fibers, films and other shaped objects having tions, or as high as about 290 C., but a temperature of good physical properties. about 275 C. is preferred. The glycolysis step is com 4,259,478 3 4. pleted in the laboratory in about 5 min. if the glycolysis A mixture of 96.0 g (0.50 mole) of scrap polyethylene temperature is about 275 C. Longer times are required terephthalate (I.V. 0.70) and 31.9 g (0.155 mole) 70% at lower temperatures. A vacuum of about 0.5 millime 1,4-cyclohexanedimethanol/methanol solution is placed ter is then applied, and stirring is continued until a high in a 500-ml flask equipped with a stirrer, a short distilla melt viscosity polymer is obtained. During this poly tion column and inlet for nitrogen. The flask is lowered condensation step, ethylene glycol is eliminated. If the into a metal bath maintained at 110' C. The mixture is copolymer has a high enough crystalline melting point heated under a nitrogen atmosphere with stirring to a (at least about 200 C.), its molecular weight may be temperature of 275 C. A very low melt viscosity prod increased by heating particles of the polymer in an inert uct is obtained within 5 min. A vacuum of 0.3 millimeter atmosphere or under reduced pressure at a temperature 10 of mercury is then applied over a period of 10 min. just below the softening point of the polymer by con After stirring is continued under 0.3 millimeter of mer ventional solid-phase polymerization. cury at 275 C. for 44 min., a high-melt viscosity, very Using the melt process polyethylene terephthalate light gray polymer is obtained. The polymer has an may be modified with 3 to 95 mole % 1,4-cyclohex inherent viscosity of 0.67 and a glass transition tempera anedimethanol and polyethylene terephthalate/cy 15 ture of 77 C. Gas chromatographic analysis of the clohexanedimethanol polyesters may be modified with hydrolyzed polymer shows that the polymer contains up to 95 mole % 1,4-cyclohexanedimethanol. Since 29.8%. 1,4-cyclohexanedimethanol. Injection-molded 1,4-cyclohexanedimethanol has a boiling point of about bars have the following properties: tensile strength 6700 285 C. and essentially none is lost during the polymeri psi, elongation 150%, flexural modulus 2.7x105 psi and zation, the theoretical amount of 1,4-cyclohexanedime 20 notched Izod impact strength 1.0 ft-lb/in. of notch. These properties are very similar to those obtained from thanol can be used in the preparation of the copolymers. the same copolymer prepared from dimethyl tere The 1,4-cyclohexanedimethanol may be the cis or trans phthalate, ethylene glycol, and 1,4-cyclohexanedime isomer, but the commercially available 30/70.cis/trans thanol. isomer mixture is preferred. Since a very short time is 25. required to carry out glycolysis of the polyesters of this EXAMPLE 2 invention by the 1,4-cyclohexanedimethanol, the time This example illustrates the preparation of a copoly needed to prepare the copolymers of this invention is mer from poly(ethylene terephthalate) and 5 mole % considerably less than the time required to prepare the 1,4-cyclohexanedimethanol. . . . same copolymers by the conventional procedure, using 30, A copolymer is prepared with 0.5 mole of scrap poly dimethyl terephthalate, ethylene glycol, and 1,4- ethylene terephthalate (I.V. 0.32) and 0.025 mole (5 cyclohexanedimethanol. mole %) of 1,4-cyclohexanedimethanol by the proce The inherent viscosity of the copolyesters of this dure of Example 1. A clear, very light gray polymer is invention is at least 0.4 and preferably at least 0.6. obtained. The polymer has an inherent viscosity of 0.53, Tough films are obtained by pressing or by extrusion. 35 glass transition temperature of 75° C. and crystalline Molding plastics having good properties are obtained melting point of 239" C. Gas chromatographic analyses by injection molding at about 240-300' C., depending on the melting point of the copolyester. In addition to of the hydrolyzed polymer shows that the polymer plastics, the compositions of this invention may be fabri contains 5.5%. 1,4-cyclohexanedimethanol. cated to give other types of shaped objects, such as EXAMPLE 3 foamed plastics, fibers, films, extruded shapes, and coat This example illustrates the preparation of a copoly ings. The compositions of this invention also may con mer from poly(ethylene terephthalate) and 90 mole % tain nucleating agents, fibers, pigments, glass fibers, 1,4-cyclohexanedimethanol. asbestos fibers, antioxidants, plasticizers, lubricants, and A copolymer is prepared with 0.5 mole of polyethyl other additives. 45 ene terephthalate and 0.45 mole (90 mole %) of 1,4- The following examples are submitted for a better cyclohexanedimethanol by the procedure of Example 1. understanding of the invention. All inherent viscosities A clear, very pale yellow polymer is obtained. The are determined at 25' C. in a (60/40 by weight) mixture polymer has an inherent viscosity of 0.66, glass transi of phenol/tetrachloroethane at a concentration of 0.5 tion temperature of 86' C. and crystalline melting point g/100 ml. The melting points and glass transition tem 50 of 255' C. Gas chromatographic analysis of the hydro peratures are determined with a Perkin-Elmer DSC-2 lyzed polymer shows that the polymer contains 87.2 differential scanning calorimeter. mole %. 1,4-cyclohexanedimethanol. The 1,4-cyclohexanedimethanol used for glycolysis of the polyesters may be the cis or trans isomer, but the EXAMPLE 4 commercially available 30/70 cis/trans isomer ratio is 55 This example illustrates the preparation of copo used in the examples below. ly(90/10 ethylene terephthalate/cyclohex The compositions are dried in an oven at 60° C. over ylenedimethylene terephthalate) by reacting poly(ethy night and injection molded to give 2:XX 1/16-in. lene terephthalate) and copoly(70/30 ethylene tereph tensile bars and 5XX-ins. flexure bars for testing. thalate/cyclohexylenedimethylene terephthalate) with ASTM procedures are used for measuring the tensile 1,4-cyclohexanedimethanol. strength and elongation (ASTM D1708) flexural mod A copolymer is prepared with 96 g (0.50 mole) poly ules (ASTM D790) and Izod impact strength (ASTM ethylene terephthalate, 21.6 g (0.10 mole) copoly(70/30 D256 Method A). ethylene terephthalate/1,4-cyclohexylenedimethylene EXAMPLE 1. terephthalate) and 4.3 g (0.030 mole) 1,4-cyclohex 65 anedimethanol by the procedure of Example 1. The This example illustrates the preparation of a copoly polymer has an inherent viscosity of 0.52, glass transi from polyethylene terephthalate by modification tion temperature of 72 C. and melting point of 227 C. with 30 mole % 1,4-cyclohexanedimethanol. Gas chromatographic analysis of the hydrolyzed poly 4,259,478 5 6 mer shows that the polymer contains 10.1% 1,4- 4. Process according to claim 1 wherein said polymer cyclohexanedimethanol. is heated to a temperature of about 275 C. in step (b) and maintained at such temperature for a time of at least EXAMPLE 5 5 minutes. This example illustrates the preparation of copo- 5 5. Process for preparing linear, high molecular ly(62/38 1,4-cyclohexylenedimethylene tereph weight copolyesters from polyesters or copolyesters, thalate/ethylene terephthalate) from copoly(70/30 eth the acid component of which consists of at least 70 mole ylene terephthalate/cyclohexylene terephthalate) and percent terephthalic acid and the diol component of 1,4-cyclohexanedimethanol. which consists of at least 70 mole percent ethylene A copolymer is prepared with 0.50 mole copo- 10 glycol which comprises ly(70/30 ethylene terephthalate/1,4-cyclohex (a) heating said polymer to a temperature of from ylenedimethylene terephthalate) and 0.16 mole 1,4- about 200 C. to about 290 C. in the presence of cyclohexanedimethanol by the procedure of Example 1. about 3 mole percent to an amount equivalent to A high-melt viscosity, clear, very pale yellow polymer the mole percent of ethylene glycol of 1,4- cyclohexanedimethanol to thereby glycolize said is obtained having an I.V. of 0.64. 15 polymer, EXAMPLE 6 (b) distilling out at least a portion of the ethylene This example illustrates the preparation of copo glycol from the glycolysis mixture, and ly(87/13 ethylene terephthalate/1,4-cyclohex (c) polycondensing the glycolysis mixture to form a ylenedimethylene terephthalate) by solid state polymer- 20 copolyester of which at least a portion of ethylene ization. glycol units are replaced by 1,4-cyclohexanedime thanol units and the inherent viscosity is at least A copolymer is prepared with 0.50 mole of poly 0.4. (ethylene terephthalate) and 0.065 mole (13 mole %) of. 6. Process according to claim 5 wherein the acid 1,4-cyclohexanedimethanol by the procedure of Exam component of said polyester or copolyester comprises ple 1. The copolymer, obtained with an inherent viscos- 25 from about 70 to about 99.5 mole percent terephthalic ity of 0.61, is ground to pass a 20-mesh screen. Solid acid and from about 30 to about 0.5 mole percent of an state build-up is accomplished by heating the particles aliphatic, alicyclic or aromatic dicarboxylic acid other under reduced pressure (0.1 mm Hg) at 23-200 C. than terephthalic. over a period of 2 hr. and at 200 C. for 12 hr. the poly 7. Process according to claim 5 wherein the diol mer has an inherent viscosity of 0.81 and a crystalline 30 component of said polyester or copolyester comprises melting point of 219 C. from about 70 to about 99.5 mole percent of ethylene Unless otherwise specified, all parts, percentages, glycol and from about 30 to about 0.5 mole percent of ratios, etc., are by weight. another aliphatic glycol having from 2 to 8 carbon The invention has been described in detail with par atOS. ticular reference to preferred embodiments thereof, but 35 8. Process for preparing linear, high molecular it will be understood that variations and modifications weight copolyesters from copolyesters, the acid compo can be effected within the spirit and scope of the inven nent of which consists of at least 70 mole percent ter tion. ephthalic acid and the diol component of which consists We claim: of at least 70 mole percent of a mixture of ethylene 1. Process for preparing linear, high molecular 40 glycol and 1,4-cyclohexanedimethanol in a mole ratio of weight copolyesters from polymers selected from the from 20:80 to 97:3, said process comprising group consisting of (A) polyesters or copolyesters, the (a) heating said polymer to a temperature of from acid component of which consists of at least 70 mole about 200 C. to about 290 C. in the presence of percent terephthalic acid and the diol component of about 3 mole percent to an amount equivalent to which consists of at least 70 mole percent ethylene 45 the mole percent of ethylene glycol of 1,4- glycol and (B) copolyesters, the acid component of cyclohexanedimethanol to thereby glycolize said which consists of at least 70 mole percent terephthalic polymer, - acid and the diol component of which consists of at least (b) distilling out at least a portion of the ethylene 70 mole percent of a mixture of ethylene glycol and glycol from the glycolysis mixture, and 1,4-cyclohexanedimethanol in a mole ratio of from 50 (c) polycondensing the glycolysis mixture to form a 20:80 to 97:3, said process comprising copolyester of which at least a portion of ethylene (a) heating said polymer to a temperature of from glycol units are replaced by 1,4-cyclohexanedime about 200 C. to about 290 C. in the presence of thanol units and the inherent viscosity is at least about 3 mole percent to an amount equivalent to 0.4. the mole percent of ethylene glycol of 1,4-55 9. Process according to claim 8 wherein the acid cyclohexanedimethanol to thereby glycolize said component of said polyester or copolyester comprises polymer, from about 70 to about 99.5 mole percent terephthalic (b) distilling out at least a portion of the ethylene acid and from about 30 to about 0.5 mole percent of an glycol from the glycolysis mixture, and aliphatic, alicyclic or aromatic dicarboxylic acid other (c) polycondensing the glycolysis mixture to form a 60 than terephthalic. copolyester of which at least a portion of ethylene 10, Process according to claim 8 wherein the diol glycol units are replaced by 1,4-cyclohexanedime component of said polyester or copolyester comprises thanol units and the inherent viscosity is at least from about 70 to about 99.5 mole percent of a mixture of 0.4. ethylene glycol and 1,4-cyclohexanedimethanol in a 2. Process according to claim 1 wherein said polymer 65 mole ratio of from 20:80 to 97:3 and from about 30 to has an inherent viscosity of at least 0.6. about 0.5 mole percent of another aliphatic glycol hav 3. Process according to claim 2 wherein said polymer ing from 2 to 8 carbon atoms. has an inherent viscosity of from about 0.4 to about 0.7. k s k k