SEMIAROMATIC POLYESTER, AND PREPARATION METHOD AND APPLICATION THEREOF

Abstract

Disclosed in the present invention is a semiaromatic polyester, a preparation method and application thereof. Having a specific segment length and carboxyl group content, the semiaromatic polyester provides a balance of degradation rate and mechanical properties, compared with known semiaromatic polyesters. The 30-day weight retention of the semiaromatic polyester obtained in the present invention may be contained to from 45 to 70%.

Claims

1. A semiaromatic polyester, comprising derivatives formed by the following components: a first component A, based on a total molar amount of the first component A, comprising: a1) from 40 to 60 mol % of at least one aliphatic dicarboxylic acid or ester derivatives thereof or anhydride derivatives thereof, a2) from 40 to 60 mol % of at least one aromatic dicarboxylic acid or ester derivatives thereof or anhydride derivatives thereof, a3) from 0 to 5 mol % of a compound containing sulfonate groups; a second component B with at least equimolar amount with respect to the first component A, comprising diols having from 2 to 12 carbon atoms; and a third component C, based on the total molar amount of the first component A, being one or more selected from the following: c1) from 0 to 5 mol % of a compound containing at least 3 hydroxy groups, c2) from 0 to 5 mol % of a dihydroxy compound containing an ether group, c3) from 0 to 25 mol % of a hydroxycarboxylic acid or cyclic derivatives thereof, and c4) from 0 to 25 mol % of an amino alkanol having from 2 to 12 carbon atoms, or an amino cycloalkanol having from 2 to 12 carbon atoms, c5) from 0 to 25 mol % of a diamine having from 1 to 12 carbon atoms, and c6) from 0 to 15 mol % of an aminocarboxylic acid compound, wherein a percentage of at least one of components c1) to c6) is not 0, and a total of molar percentages of c1) to c6) is 100%; wherein an average segment length of a repeating unit Ba2 derived from the second component B and the component a2 of the semiaromatic polyester, is from 1.85 to 2.25 as calculated using .sup.1HNMR; and a carboxyl group content of the semiaromatic polyester is from 5 to 60 mmol/kg.

2. The semiaromatic polyester according to claim 1, wherein the average segment length of the repeating unit Ba2 derived from the second component B and the component a2 of the semiaromatic polyester, is from 1.87 to 2.0 as calculated using .sup.1HNMR; and the carboxyl group content of the semiaromatic polyester is from 10 to 35 mmol/kg.

3. The semiaromatic polyester according to claim 1, wherein a molar amount of a2 in the first component A is from 45 to 50 mol %.

4. The semiaromatic polyester according to claim 1, wherein a molar amount of the third component C is from 0.01 to 4 mol %, based on the total molar amount of the first component A.

5. The semiaromatic polyester according to claim 1, wherein the third component C is glycerol, pentaerythritol or trimethylolpropane.

6. The semiaromatic polyester according to claim 4, wherein the third component C is glycerol, pentaerythritol or trimethylolpropane.

7. The semiaromatic polyester according to claim 1, wherein the semiaromatic polyester further comprises a fourth component D, the fourth component D being a chain extender; and a molar amount of the fourth component D is from 0.01 to 5 mol %, based on the total molar amount of the first component A.

8. The semiaromatic polyester according to claim 7, wherein the chain extender is one or a mixture of more selected from a group consisting of isocyanates, isocyanurates, peroxides, epoxides, oxazolines, oxazines, carbodiimides and polycarbodiimides, which have two or more functional groups.

9. The semiaromatic polyester according to claim 1, wherein the semiaromatic polyester comprises derivatives formed by the following components: the first component A, comprising: a1) a C4-C12 aliphatic dicarboxylic acid or ester derivatives thereof, and a2) terephthalic acid or ester derivatives thereof, the second component B: butanediol or propanediol; the third component C: glycerol, pentaerythritol or trimethylolpropane; and a fourth component D: hexamethylene diisocyanate, an epoxide, an oxazoline or a carbodiimide.

10. The semiaromatic polyester according to claim 1, wherein the semiaromatic polyester has a viscosity of from 150 to 350 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999.

11. A preparation method of the semiaromatic polyester according to claim 1, comprising the following steps of: S1, physically mixing a1 of the first component A with the second component B and the third component C in a first esterification reactor at ambient temperature, and meanwhile, physically mixing a2 of the first component A, the second component B and the third component C under the action of a portion of a catalyst in a second esterification reactor at ambient temperature, and then heating the mixtures separately to from 150 to 280° C. for esterification reactions for 1 to 2 hours so as to obtain esterification products Ba1 and Ba2, respectively; S2, mixing the two esterification products Ba1 and Ba2 obtained in step S1 for a primary polycondensation reaction under the action of the remaining amount of the catalyst at a reaction temperature of from 230 to 270° C. until a reaction product thereof reaches a viscosity of from 20 to 60 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999; and S3, transferring a product of the primary polycondensation reaction in step S2 into a finisher for continuous polycondensation reaction at a temperature of from 220 to 270° C. until a reaction product thereof reaches a viscosity of from 150 to 350 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999, and until the average segment length of the repeating unit Ba2 derived from the second component B and the component a2 in the reaction product of the continuous polycondensation reaction, is from 1.85 to 2.25, and the carboxyl group content of the reaction product of the continuous polycondensation reaction is from 5 to 60 mmol/kg, to obtain the semiaromatic polyester.

12. A preparation method of the semiaromatic polyester according to claim 1, comprising the following steps of: S1, physically mixing an aromatic polyester resin with a1 and a3 of the first component A, the second component B and the third component C at ambient temperature, and performing a transesterification reaction at 150 to 180° C. to obtain an esterification product; S2, adding a catalyst into the esterification product for a primary polycondensation reaction at a temperature of from 230 to 270° C. until a reaction product thereof reaches a viscosity of 20 to 60 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999; and S3, transferring the reaction product of the primary polycondensation reaction in step S2 into a finisher for continuous polycondensation reaction at a temperature of from 220 to 270° C. until a reaction product thereof reaches a viscosity of 150 to 350 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999, and until the average segment length of the repeating unit Ba2 derived from the second component B and the component a2 in the reaction product of the continuous polycondensation reaction, is from 1.85 to 2.25, and the carboxyl group content of the reaction product of the continuous polycondensation reaction is from 5 to 60 mmol/kg, so as to obtain a semiaromatic polyester.

13. The preparation method of the semiaromatic polyester according to claim 11, wherein in the S3, a fourth component D is added during the continuous polycondensation reaction, and a reactive extrusion is performed with a twin-screw extruder.

14. The preparation method of the semiaromatic polyester according to claim 12, wherein in the S3, a fourth component D is added during the continuous polycondensation reaction, and reactive extrusion is performed with a twin-screw extruder.

15. A semiaromatic polyester molding composition, based on weight percentage, comprising from 5 to 95 wt % of the semiaromatic polyester according to claim 1; from 5 to 95 wt % of an additive and/or other polymers; and from 0 to 70 wt % of a reinforcement material and/or a filler.

16. Use of the semiaromatic polyester according to claim 1 in preparing compostable products, characterized in that, the compostable products are fibers, thin films or containers.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0108] Unless otherwise specified, the raw materials, reagents and solvents used herein are commercially purchased, without any further processing. Examples are used hereinafter to further demonstrate the present invention in details. However, the embodiments of the present invention is not limited by the following examples, and any other changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present invention, shall be equivalent substitutions and are included in the scope of protection of the present invention. Moreover, unless otherwise specified, “parts” and “%” used herein refers to “parts by mass” and “% by mass”, respectively.

[0109] Test methods:

[0110] Viscosity of semiaromatic polyesters:

[0111] The viscosity of semiaromatic polyesters was measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C., specimen concentration being 5 mg/ml, in accordance with GB/T 17931-1999.

[0112] Carboxyl group content:

[0113] The acid number A.sub.N (mg KOH/g) was determined first according to DIN EN 12634 of October 1998, followed by a calculation of the carboxyl group content (mmol/kg), which equals to A.sub.N/56×10.sup.3. The solvent mixture used comprised a mixture of 1 part by volume of DMSO, 8 parts by volume of propan-2-ol, and 7 parts by volume of toluene. The specimen of semiaromatic polyester was heated to 50° C., and the circuit used a single-rod electrode and potassium chloride filling. The standard solution used was tetramethylammonium hydroxide.

[0114] Average segment length of Ba2:

[0115] The average segment length of Ba2 was measured with Bruker AV 400 NMR spectrometer, using deuterochloroform (CDCl.sub.3) as solvent and tetramethylsilane (TMS) as internal reference. Data of segment length of Ba2 was obtained by calculations based on analysis of the test results by referring to the method on pages from 32 to 34 of the PhD thesis by Wang Xiaohui (Study on new process of synthesis and properties of biodegradable aliphatic-aromatic copolyesters, Wang Xiaohui, PhD thesis, Beijing University of Chemical Technology, 2011).

[0116] Thirty-day weight retention:

[0117] The biodegradation test of semiaromatic polyesters was carried out according to GB/T 19277-2003. Firstly, the semiaromatic polyester specimen was pressed into a thin film of 0.10 mm thick, and cut into a specimen sheet of 1.2 cm×2.0 cm, the weight of which is referred to as a.sub.o. Then the specimen sheet was buried in composting soil and placed in a constant temperature chamber. The composting soil was municipal waste compost after 56 to 70 days of aeration and sieving. The test temperature was set constant at (58±2)° C. The compost specimen sheet was taken out after 30 days, washed, dried, and weighed, and the obtained weight of the specimen was recorded as a.sub.1. The 30-day weight retention=a.sub.1/a.sub.0×100%. The higher the 30-day weight retention, the more difficult it is for the material to degrade; whereas the lower the 30-day weight retention, the faster the material degrades.

[0118] Tensile properties of films:

[0119] The semiaromatic polyester was produced into thin films of 25±1 μm, and tested according to ISO 527 standards.

[0120] In all examples and comparative examples of the present invention, butanediol was overfed during polyester synthesis and the molar content of alcohols in the finished polymer is equal to the sum of the molar content of diacids. Limited in the following tables are the molar amounts of alcohols in the finished resin.

EXAMPLE 1

[0121] S1. 437 kg/h of terephthalic acid, 323 kg/h of butanediol, 0.538 kg/h of glycerol and 0.506 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in a first esterification reactor, then the mixture was esterified at 240° C. for from 60 to 120 minutes at a pressure of 0.45 bar, and an esterification product Ba1 was obtained; 437 kg/h of adipic acid, 367 kg/h of butanediol and 0.612 kg/h of glycerol were physically mixed at ambient temperature in a second esterification reactor, then the mixture was esterified at 180° C. for 120 minutes at a pressure of 1.0 bar, and an esterification product Ba2 was obtained.

[0122] S2. The esterification products Ba1 and Ba2 were passed through a static mixer and into a vertical continuous stirred tank reactor. The mixture was heated to 260° C. And 0.276 kg/h of tetrabutyl orthotitanate was fed into the reactor. The pressure was lowered to 100 mbar. Most of the excess butanediol was removed by distillation. After a reaction time of 60 minutes, the reaction product reached a viscosity of 24 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999.

[0123] S3. After addition of 0.23 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation. The obtained polyester was introduced into a twin-screw extruder, and 9.2 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 5 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 1 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00001 TABLE 1 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 437 166.13 2,630 46.80 acid adipic acid 437 146.14 2,990 53.20 butanediol 690 90.12 7,656 100.00 glycerol 1.15 92.09 12.49 0.22 tetrabutyl 0.782 340.32 2.30 0.04 orthotitanate phosphorous 0.23 82 2.80 0.05 acid HDI 9.2 168.2 54.70 0.97

EXAMPLE 2

[0124] S1. 437 kg/h of terephthalic acid, 323 kg/h of butanediol, 0.538 kg/h of glycerol and 0.506 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in a first esterification reactor, then the mixture was esterified at 240° C. for from 60 to 120 minutes at a pressure of 0.45 bar, and an esterification product Ba2 was obtained; 525 kg/h of sebacic acid, 367 kg/h of butanediol and 0.612 kg/h of glycerol were physically mixed at ambient temperature in a second esterification reactor, then the mixture was esterified at 180° C. for 120 minutes at a pressure of 1.0 bar, and an esterification product Ba1 was obtained.

[0125] S2. The esterification products Ba1 and Ba2 were passed through a static mixer and into a vertical continuous stirred tank reactor. The mixture was heated to 260° C. And 0.276 kg/h of tetrabutyl orthotitanate was fed into the reactor. The pressure was lowered to 100 mbar. Most of the excess butanediol was removed by distillation. After a reaction time of 60 minutes, the reaction product reached a viscosity of 26 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999.

[0126] S3. After addition of 0.23 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation. The obtained polyester was introduced into a twin-screw extruder, and 9.2 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 5 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 2 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00002 TABLE 2 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 437 166.13 2,630 50.33 acid sebacic acid 525 202.25 2,596 49.67 butanediol 690 90.12 7,656 100.00 glycerol 1.15 92.09 12.49 0.24 tetrabutyl 0.782 340.32 2.30 0.04 orthotitanate phosphorous 0.23 82 2.80 0.05 acid HDI 9.2 168.2 54.70 1.05

EXAMPLE 3

[0127] S1. 437 kg/h of terephthalic acid, 272 kg/h of propanediol, 0.538 kg/h of glycerol and 0.506 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in a first esterification reactor, then the mixture was esterified at 240° C. for from 60 to 120 minutes at a pressure of 0.45 bar, and an esterification product Ba2 was obtained; 425 kg/h of adipic acid, 301 kg/h of propanediol and 0.612 kg/h of glycerol were physically mixed at ambient temperature in a second esterification reactor, then the mixture was esterified at 180° C. for 120 minutes at a pressure of 1.0 bar, and an esterification product Ba1 was obtained.

[0128] S2. The esterification products Ba1 and Ba2 were passed through a static mixer and into a vertical continuous stirred tank reactor. The mixture was heated to 260° C. And 0.276 kg/h of tetrabutyl orthotitanate was fed into the reactor. The pressure was lowered to 100 mbar. Most of the excess butanediol was removed by distillation. After a reaction time of 60 minutes, the reaction product reached a viscosity of 28 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T17931-1999.

[0129] S3. After addition of 0.23 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation. The obtained polyester was introduced into a twin-screw extruder, and 9.2 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 5 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 3 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00003 TABLE 3 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 437 166.13 2,630 47.49 acid adipic acid 425 146.14 2,908 52.51 propanediol 573 76.09 7,688 100.00 glycerol 1.15 92.09 12.49 0.23 tetrabutyl 0.782 340.32 2.30 0.04 orthotitanate phosphorous 0.23 82 2.80 0.05 acid HDI 9.2 168.2 54.70 0.99

EXAMPLE 4

[0130] S1. 437 kg/h of terephthalic acid, 377 kg/h of butanediol, 0.538 kg/h of glycerol and 0.506 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in a first esterification reactor, then the mixture was esterified at 240° C. for from 60 to 120 minutes at a pressure of 0.45 bar, and an esterification product Ba2 was obtained; 437 kg/h of adipic acid, 313 kg/h of butanediol and 0.612 kg/h of glycerol were physically mixed at ambient temperature in a second esterification reactor, then the mixture was esterified at 180° C. for 120 minutes at a pressure of 1.0 bar, and an esterification product Ba1 was obtained.

[0131] S2. The esterification products Ba1 and Ba2 were passed through a static mixer and into a vertical continuous stirred tank reactor. The mixture was heated to 260° C. And 0.276 kg/h of tetrabutyl orthotitanate was fed into the reactor. The pressure was lowered to 100 mbar. Most of the excess butanediol was removed by distillation. After a reaction time of 60 minutes, the reaction product reached a viscosity of 30 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999.

[0132] S3. After addition of 0.23 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation.

[0133] The obtained polyester was introduced into a twin-screw extruder, and 9.2 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 5 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 4 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00004 TABLE 4 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 437 166.13 2,630 46.80 acid adipic acid 437 146.14 2,990 53.20 butanediol 690 90.12 7,656 100.00 glycerol 1.15 92.09 12.49 0.22 tetrabutyl 0.782 340.32 2.30 0.04 orthotitanate phosphorous 0.23 82 2.80 0.05 acid HDI 9.2 168.2 54.70 0.97

EXAMPLE 5

[0134] S1. 578 kg/h of a PBT resin (L08XM, intrinsic viscosity of 0.85 dL/g, Jiangsu Heshili New Material Co., Ltd.), 437 kg/h of adipic acid, 312 kg/h of butanediol, 0.612 kg/h of glycerol and 0.506 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in an esterification reactor, then the mixture was reacted at 180° C. for 120 minutes at a pressure of 1.0 bar, and a product E2 was obtained.

[0135] S2. The esterification product E2 was transferred into a vertical continuous stirred tank reactor, and heated to 260° C. And 0.276 kg/h of tetrabutyl orthotitanate was fed into the reactor.

[0136] The pressure was lowered to 100 mbar for a constant temperature reaction for 180 minutes. Most of the excess butanediol was removed by distillation. At this time, the reaction product reached a viscosity of 35 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999.

[0137] S3. After addition of 0.23 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation. The obtained polyester was introduced into a twin-screw extruder, and 9.2 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 5 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 5 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00005 TABLE 5 Content of each component in the resin, in mol %, based on the total molar amount of the Dose in Molecular Dose in first component kg/h weight in g/mol mol/h A of 100% PBT 578 220 (molecular 2,627 46.77 (molar weight of the amount of repeating unit terephthalic in PBT) acid from PBT) adipic acid 437 146.14 2,990 53.23 butanediol 312 90.12 3,462 100.00 glycerol 0.612 92.09 6.65 0.12 tetrabutyl 0.782 340.32 2.30 0.04 orthotitanate phosphorous 0.23 82 2.80 0.05 acid HDI 9.2 168.2 54.70 0.97

EXAMPLE 6

[0138] S1. 437 kg/h of terephthalic acid, 323 kg/h of butanediol, 0.538 kg/h of glycerol and 0.506 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in a first esterification reactor, then the mixture was esterified at 240° C. for from 60 to 120 minutes at a pressure of 0.45 bar, and an esterification product Ba2 was obtained; 437 kg/h of adipic acid, 367 kg/h of butanediol and 0.612 kg/h of glycerol were physically mixed at ambient temperature in a second esterification reactor, then the mixture was esterified at 180° C. for 120 minutes at a pressure of 1.0 bar, and an esterification product Ba1 was obtained.

[0139] S2. The esterification products Ba1 and Ba2 were passed through a static mixer and into a vertical continuous stirred tank reactor. The mixture was heated to 260° C. And 0.276 kg/h of tetrabutyl orthotitanate was fed into the reactor. The pressure was lowered to 100 mbar. Most of the excess butanediol was removed by distillation. After a reaction time of 120 minutes, the reaction product reached a viscosity of 32 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T17931-1999.

[0140] S3. After addition of 0.23 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation. The above-mentioned polyester was introduced into a twin-screw extruder, and 9.2 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 15 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 6 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00006 TABLE 6 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 437 166.13 2.630 46.80 acid adipic acid 437 146.14 2,990 53.20 butanediol 690 90.12 7,656 100.00 glycerol 1.15 92.09 12.49 0.22 tetrabutyl 0.782 340.32 2.30 0.04 orthotitanate phosphorous 0.23 82 2.80 0.05 acid HDI 9.2 168.2 54.70 0.97

EXAMPLE 7

[0141] S1. 608 kg/h of terephthalic acid, 449 kg/h of butanediol, 0.748 kg/h of glycerol and 0.653 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in a first esterification reactor, then the mixture was esterified at 240° C. for from 60 to 120 minutes at a pressure of 0.45 bar, and an esterification product Ba2 was obtained; 437 kg/h of adipic acid, 366 kg/h of butanediol and 0.612 kg/h of glycerol were physically mixed at ambient temperature in a second esterification reactor, then the mixture was esterified at 180° C. for 120 minutes at a pressure of 1.0 bar, and an esterification product Ba1 was obtained.

[0142] S2. The esterification products Ba1 and Ba2 were passed through a static mixer and into a vertical continuous stirred tank reactor. The mixture was heated to 260° C. And 0.267 kg/h of tetrabutyl orthotitanate was fed into the reactor. The pressure was lowered to 100 mbar. Most of the excess butanediol was removed by distillation. After a reaction time of 60 minutes, the reaction product reached a viscosity of 27 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T17931-1999.

[0143] S3. After addition of 0.27 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation.

[0144] The obtained polyester was introduced into a twin-screw extruder, and 10.9 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 5 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 7 for the composition of raw materials and

[0145] Table 14 for the results of the properties of the product.

TABLE-US-00007 TABLE 7 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 608 166.13 3.660 55.03 acid adipic acid 437 146.14 2.990 44.97 butanediol 815 90.12 9.043 100.00 glycerol 1.36 92.09 14.77 0.22 tetrabutyl 0.92 340.32 2.70 0.04 orthotitanate phosphorous 0.27 82 3.32 0.05 acid HDI 10.9 168.2 64.80 0.97

COMPARATIVE EXAMPLE 1:

[0146] S1. 437 kg/h of terephthalic acid, 323 kg/h of butanediol, 0.538 kg/h of glycerol and 0.782 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in a first esterification reactor, then the mixture was esterified at 240° C. for from 60 to 120 minutes at a pressure of 0.45 bar, and an esterification product Ba2 was obtained; 437 kg/h of adipic acid, 367 kg/h of butanediol and 0.612 kg/h of glycerol were physically mixed at ambient temperature in a second esterification reactor, then the mixture was esterified at 180° C. for 120 minutes at a pressure of 1.0 bar, and an esterification product Ba1 was obtained.

[0147] S2. The esterification products Ba1 and Ba2 were passed through a static mixer and into a vertical continuous stirred tank reactor. The mixture was heated to 260° C. Then, the pressure was lowered to 100 mbar. Most of the excess butanediol was removed by distillation. After a reaction time of 60 minutes, the reaction product reached a viscosity of 20 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999.

[0148] S3. After addition of 0.23 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation. The obtained polyester was introduced into a twin-screw extruder, and 9.2 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 5 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 8 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00008 TABLE 8 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 437 166.13 2,630 46.80 acid adipic acid 437 146.14 2,990 53.20 butanediol 690 90.12 7,656 100.00 glycerol 1.15 92.09 12.49 0.22 tetrabutyl 0.782 340.32 2.30 0.04 orthotitanate phosphorous 0.23 32 2.80 0.05 acid HDI 9.2 168.2 54.70 0.97

COMPARATIVE EXAMPLE 2

[0149] S1. 437 kg/h of terephthalic acid, 690 kg/h of butanediol, 437 kg/h of adipic acid, 1.15 kg/h of glycerol and 0.506 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in an esterification reactor, then the mixture was esterified at 240° C. for from 60 to 120 minutes at a pressure of 0.45 bar, and an esterification product F was obtained.

[0150] S2. The esterification product F was transferred to a vertical continuous stirred tank reactor, and heated to 260° C. And 0.276 kg/h of tetrabutyl orthotitanate was fed into the reactor. The pressure was lowered to 100 mbar. Most of the excess butanediol was removed by distillation.

[0151] After a reaction time of 60 minutes, the reaction product reached a viscosity of 26 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999.

[0152] S3. After addition of 0.23 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation.

[0153] The above-mentioned polyester was introduced into a twin-screw extruder, and 9.2 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 5 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 9 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00009 TABLE 9 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 437 166.13 2,630 46.80 acid adipic acid 437 146.14 2,990 53.20 butanediol 690 90.12 7,656 100.00 glycerol 1.15 92.09 12.49 0.22 tetrabutyl 0.782 340.32 2.30 0.04 orthotitanate phosphorous 0.23 82 2.80 0.05 acid HDI 9.2 168.2 54.70 0.97

COMPARATIVE EXAMPLE 3

[0154] At ambient temperature, 874 g of terephthalic acid, 1,380 g of butanediol, 874 g of adipic acid, 2.3 g of glycerol and 1.012 g of tetrabutyl orthotitanate were physically mixed in a 5-Liter stainless steel reactor, then the mixer was esterified at 240° C. as water was removed by distillation till the end of the esterification reaction when the amount of product water obtained from the reaction reached a theoretical water production level; then 0.552 g of tetrabutyl orthotitanate and 0.46 g of phosphorous acid were added to the reaction system, and after gradual pressure reduction, the final reaction temperature was from 270 to 275° C. and the pressure was lower than 100 Pa.

[0155] The end point of the polycondensation reaction was determined according to the growth rate of stirring power. Then the reaction system was restored to ambient pressure with nitrogen, and polyester product was obtained after water cooling pelletization. See Table 10 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00010 TABLE 10 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 874 166.13 5.26 46.80 acid adipic acid 874 146.14 5.98 53.20 butanediol 1380 90.12 15.31 100.00 glycerol 2.3 92.09 0.025 0.22 tetrabutyl 1.564 340.32 0.0046 0.04 orthotitanate phosphorous 0.46 82 0.0056 0.05 acid

COMPARATIVE EXAMPLE 4

[0156] At ambient temperature, 874 g of terephthalic acid, 1,380 g of butanediol, 874 g of adipic acid, 2.3 g of glycerol and 1.012 g of tetrabutyl orthotitanate were physically mixed in a 5-Liter stainless steel reactor, then the mixer was esterified at 240° C. as water was removed by distillation till the end of the esterification reaction when the amount of product water obtainable from the reaction reached a theoretical water production level; then 0.552 g of tetrabutyl orthotitanate and 0.46 g of phosphorous acid were added to the reaction system, and after gradual pressure reduction, the final reaction temperature was from 270 to 275° C., and the pressure was lower than 100 Pa.

[0157] Meanwhile 18.4 g of hexamethylene diisocyanate (HDI) was metered into the reaction system at a set temperature of 240° C. After a residence time of 5 minutes, the reaction system was restored to ambient pressure with nitrogen, and polyester product was obtained after water cooling pelletization. See Table 11 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00011 TABLE 11 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 874 166.13 5.26 46.80 acid adipic acid 874 146.14 5.98 53.20 butanediol 1380 90.12 15.31 100.00 glycerol 2.3 92.09 0.025 0.22 tetrabutyl 1.564 340.32 0.0046 0.04 orthotitanate phosphorous 0.46 82 0.0056 0.05 acid HDI 18.4 168.2 0.1094 0.97

COMPARATIVE EXAMPLE 5

[0158] S1. 793 kg/h of terephthalic acid, 585 kg/h of butanediol, 0.978 kg/h of glycerol and 0.753 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in a first esterification reactor, then the mixture was esterified at 240° C. for from 60 to 120 minutes at a pressure of 0.45 bar, and an esterification product Ba1 was obtained; 437 kg/h of adipic acid, 366 kg/h of butanediol and 0.612 kg/h of glycerol were physically mixed at ambient temperature in a second esterification reactor, then the mixture was esterified at 180° C. for 120 minutes at a pressure of 1.0 bar, and an esterification product Ba2 was obtained.

[0159] S2. The esterification products Ba1 and Ba2 were passed through a static mixer and into a vertical continuous stirred tank reactor. The mixture was heated to 260° C. And 0.327 kg/h of tetrabutyl orthotitanate was fed into the reactor. The pressure was lowered to 100 mbar. Most of the excess butanediol was removed by distillation. After a reaction time of 60 minutes, the reaction product reached a viscosity of 29 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999.

[0160] S3. After addition of 0.32 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation.

[0161] The obtained polyester was introduced into a twin-screw extruder, and 12.7 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 5 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 12 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00012 TABLE 12 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 793 166.13 4,773 61.48 acid adipic acid 437 146.14 2,990 38.52 butanediol 951 90.12 10,553 100.00 glycerol 1.59 92.09 17.27 0.22 tetrabutyl 1.08 340.32 3.17 0.04 orthotitanate phosphorous 0.318 32 3.88 0.05 acid HDI 12.73 168.2 75.68 0.97

COMPARATIVE EXAMPLE 6

[0162] S1. 295 kg/h of terephthalic acid, 218 kg/h of butanediol, 0.363 kg/h of glycerol and 0.426 kg/h of tetrabutyl orthotitanate were physically mixed at ambient temperature in a first esterification reactor, then the mixture was esterified at 240° C. for from 60 to 120 minutes at a pressure of 0.45 bar, and an esterification product Ba1 was obtained; 437 kg/h of adipic acid, 366 kg/h of butanediol and 0.612 kg/h of glycerol were physically mixed at ambient temperature in a second esterification reactor, then the mixture was esterified at 180° C. for 120 minutes at a pressure of 1.0 bar, and an esterification product Ba2 was obtained.

[0163] S2. The esterification products Ba1 and Ba2 were passed through a static mixer and into a vertical continuous stirred tank reactor. The mixture was heated to 260° C. And 0.237 kg/h of tetrabutyl orthotitanate was fed into the reactor. The pressure was lowered to 100 mbar. Most of the excess butanediol was removed by distillation. After a reaction time of 60 minutes, the reaction product reached a viscosity of 31 ml/g, measured in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 and in a water bath kept at 25±0.05° C. in accordance with GB/T 17931-1999.

[0164] S3. After addition of 0.19 kg/h of phosphorous acid, the reaction mixture was transferred into a finisher and further polycondensed at a temperature of 260° C., and at a pressure of 4 mbar for from 60 to 100 minutes. The remaining excess of butanediol was removed by distillation.

[0165] The obtainable polyester was introduced into a twin-screw extruder, and 7.8 kg/h of hexamethylene diisocyanate (HDI) was metered into the polyester at a set temperature of 240° C. After a residence time of 5 minutes, the polyester was pelletized, using an underwater pelletizer, and dried to give the finished polyester product. See Table 13 for the composition of raw materials and Table 14 for the results of the properties of the product.

TABLE-US-00013 TABLE 13 Content of each component in the resin, in mol %, based on the total Molecular molar amount of the Dose in weight in Dose in first component kg/h g/mol mol/h A of 100% terephthalic 295 166.13 1,776 37.26 acid adipic acid 437 146.14 2,990 62.74 butanediol 584 90.12 6,480 100.00 glycerol 0.975 92.09 10.59 0.22 tetrabutyl 0.663 340.32 1.95 0.04 orthotitanate phosphorous 0.195 82 2.38 0.05 acid HDI 7.8 168.2 46.37 0.97

TABLE-US-00014 TABLE 14 Test results of product properties in each example and comparative example Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Viscosity in ml/g 280 275 288 205 295 263 281 Carboxyl group content in 25 28 22 37 24 39 29 mmol/kg Average segment length of Ba2 1.91 1.87 1.89 1.90 2.08 1.86 2.24 Machine-direction tensile 35 32 37 31 33 32 34 strength of films in MPa Transverse-direction tensile 38 35 40 33 36 33 37 strength of films in MPa 30-day weight retention in % 57 55 59 48 64 50 68 Comparative Comparative Comparative Comparative Comparative Comparative example 1 example 2 example 3 example 4 example 5 example 6 Viscosity in ml/g 262 281 173 277 283 277 carboxyl group content in 63 22 66 68 28 27 mmol/kg Average segment length of Ba2 1.88 1.82 1.87 1.84 2.75 1.64 Machine-direction tensile 30 33 26 31 36 28 strength of films in MPa Transverse-direction tensile 32 36 28 34 39 29 strength of films in MPa 30-day weight retention in % 40 42 39 42 90 20

[0166] It can be seen from the results in Table 14 that, the average segment length of Ba2 herein is contained between 1.85 and 2.25, and carboxyl group content is contained in a range from 5 to 60 mmol/kg, and the obtained semiaromatic polyester shows a balance between degradation rate and mechanical properties. The 30-day weight retention of the semiaromatic polyester obtained in the present invention may be contained to from 45 to 70%, and more preferably contained to from 50 to 60%. Meanwhile, the machine-direction or transverse-direction tensile strength of the films can be maintained above 30 MPa.

[0167] As demonstrated by the results of examples and comparative examples 1 to 4, the average segment length of obtained Ba2 and carboxyl group content are out of the range of the present invention in the case of different preparation processes although the same raw materials were used, and the obtained semiaromatic polyester did not have a balance between degradation rate and mechanical properties.

[0168] The average segment length of Ba2 in comparative example 5 is too large, resulting in a degradation rate that is too low for the material to degrade; whereas in comparative example 6, the average segment length of Ba2 was too small, leading to a degradation rate of the material that is too high.