A process is disclosed for preparing polyethylene terephthalate having a predetermined intrinsic viscosity which involves the direct esterification of terephthalic acid with ethylene glycol followed by the polycondensation of the esterification product using a polycondensation catalyst system containing cobalt, manganese-, and antimony-containing components.

Claims

31 · 1 independent · depth 4

31 granted claims

›1.independentA process for preparing polyethylene terephthalate having a predetermined intrinsic viscosity, comprising: (a) Reacting ethylene glycol with terephtha…+30

›2.↳ 1The process of claim 1 wherein the antimony-containing component of the catalyst employed in step (b) is at a level of from about 100 to about 278 par…d2

›3.↳ 1The process of claim 1 wherein the antimony-containing component of the catalyst employed in step (b) is at a level of from about 175 to about 278 par…d2

›4.↳ 1The process of claim 1 wherein the antimony-containing component of the catalyst employed in step (b) is at a level of from about 175 to about 254 par…d2

›5.↳ 1The process of claim 1 wherein the cobalt-containing component of the catalyst employed in step (b) is at a level of from about 15 to about 25 parts o…d2+1

›6.↳ 1The process of claim 1 wherein the manganese-containing component of the catalyst employed in step (b) is at a level of from about 55 to about 95 part…d2

›8.↳ 1The process of claim 1 wherein step (a) is performed in the presence of a catalyst that consists essentially of a cobalt-containing component of from …d2+2

›11.↳ 1The process of claim 1 wherein terephthalic acid and ethylene glycol are reacted at a mole ratio of from about 1.15 to about 1.25 moles of ethylene gl…d2

›12.↳ 1The process of claim 1 wherein the terephthalic acid employed contains less than 200 parts of 4-carboxybenzaldehyde per million parts of terephthalic …d2

›13.↳ 1The process of claim 1 wherein step (a) is performed at a temperature in the range of from about 250.degree. C. to about 280.degree. C. and at a press…d2

›14.↳ 1The process of claim 1 wherein step (a) is performed at a temperature in the range of from about 255.degree. C. to about 275.degree. C.d2

›15.↳ 1The process of claim 1 wherein step (a) is performed at a pressure in the range of from about atmospheric to about 60 pounds per square inch gauge.d2

›16.↳ 1The process of claim 1 wherein step (b) is performed at a temperature in the range of from about 270.degree. C. to about 300.degree. C. and at a press…d2+2

›19.↳ 1The process of claim 1 wherein a catalyst stabilizer is employed in step (b).d2+2

›22.↳ 1The process of claim 1, wherein step (a) is performed: (i) initially at a pressure in the range of from about 20 to about 100 pounds per square inch g…d2+7

›23.↳ 22The process of claim 22 wherein step (a)(i) is performed at a temperature in the range of from about 255.degree. C. to about 260.degree. C. and at a p…d3

›24.↳ 22The process of claim 22 wherein step (a)(ii) is performed at a temperature in the range of from about 255.degree. C. to about 260.degree. C.d3

›25.↳ 22The process of claim 22 wherein step (b)(i) is performed at a temperature in the range of from about 275.degree. C. to about 285.degree. C.d3

›26.↳ 22The process of claim 22 wherein the pressure is reduced at a rate in the range of from about 0.5 to about 2 inches of mercury per minute.d3

›27.↳ 22The process of claim 22 wherein in step (b)(i) the pressure is reduced to a predetermined pressure in the range of from about 0.5 to about 10 millimet…d3

›28.↳ 22The process of claim 22 wherein the final polymerization in step (b)(ii) is at a temperature in the range of from about 275.degree. C. to about 285.de…d3

›29.↳ 22The process of claim 22 wherein the temperature of the final polymerization in step (b)(ii) is from about 5.degree. C. to about 15.degree. C. above th…d3

›30.↳ 1The process of claim 1 wherein each of steps (a) and (b) is performed in the absence of a separate solvent.d2

›31.↳ 1The process of claim 1 wherein the reaction in step (a) is performed until at least about 97 percent of the carboxyl end groups have reacted.d2

Classifications

12 codes

USPC · US Patent Classification

528/272528/286524/413528/308.3524/127524/417528/280528/308.6524/408528/285528/308.5528/277

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