阅读说明：本技术 一种半芳香族聚酯及其制备方法和应用 (Semi-aromatic polyester and preparation method and application thereof ) 是由 张传辉 陈平绪 叶南飚 欧阳春平 麦开锦 董学腾 曾祥斌 卢昌利 蔡彤旻 于 2021-09-14 设计创作，主要内容包括：本发明提供一种半芳香族聚酯及其制备方法和应用,基于二酸的总摩尔量,本发明将二聚(1,4-丁二醇)中重复单元-CH-(2)CH-(2)CH-(2)CH-(2)-O-的摩尔含量控制为0.05-0.35mol％,可有效改善半芳香族聚酯的树脂颜色。(The invention provides a semi-aromatic polyester and a preparation method and application thereof, and the semi-aromatic polyester is prepared by using a repeating unit-CH in dimerization (1, 4-butanediol) based on the total molar amount of diacid 2 CH 2 CH 2 CH 2 The molar content of the-O-is controlled to be 0.05 to 0.35 mol%, and the resin color of the semi-aromatic polyester can be effectively improved.)

1. A semi-aromatic polyester comprising repeating units derived from:

a first component a comprising, based on the total molar amount of the first component a:

a1)35 to 65 mol%, preferably 40 to 60 mol%, of at least one aliphatic dicarboxylic acid or an ester derivative thereof or an anhydride derivative thereof,

a2)35 to 65 mol%, preferably 40 to 60 mol%, of at least one aromatic dicarboxylic acid or an ester derivative thereof or an anhydride derivative thereof,

a second component B, 1, 4-butanediol,

a third component C, dimeric (1, 4-butanediol), molecular formula HO-CH₂CH₂CH₂CH₂-O-CH₂CH₂CH₂CH₂-OH and, based on the total molar amount of the first component a, the repeating unit-CH in the third component C₂CH₂CH₂CH₂The molar content of-O-is 0.05 to 0.35 mol%.

2. Semi-aromatic polyester according to claim 1, characterized in that said component a1) is selected from oxalic acid, dimethyl oxalate, malonic acid, dimethyl malonate, succinic acid, dimethyl succinate, methylsuccinic acid, glutaric acid, dimethyl glutarate, bis (2-hydroxyethyl) glutarate, bis (3-hydroxypropyl) glutarate, bis (4-hydroxybutyl) glutarate, 2-methylglutaric acid, 3-methylglutaric acid, adipic acid, dimethyl adipate, bis (2-hydroxyethyl) adipate, bis (3-hydroxypropyl) adipate, bis (4-hydroxybutyl) adipate, 3-methylhexanedioic acid, 2,5, 5-tetramethyladipic acid, pimelic acid, suberic acid, azelaic acid, dimethyl azelate, sebacic acid, adipic acid, dimethyl azelate, sebacic acid, adipic acid, dimethyl esters, and mixtures thereof, 1, 11-undecanedicarboxylic acid, 1, 10-decanedicarboxylic acid, undecanedioic acid, 1, 12-dodecanedicarboxylic acid, hexadecanedioic acid, eicosanedioic acid, tetracosanedicarboxylic acid, dimer acid or its ester derivatives or its anhydride derivatives, preferably one or more selected from succinic acid, adipic acid, sebacic acid, 1, 12-dodecanedicarboxylic acid or its ester derivatives or its anhydride derivatives, more preferably one or two selected from adipic acid, sebacic acid or its ester derivatives or its anhydride derivatives, most preferably adipic acid or its ester derivatives or its anhydride derivatives.

3. Semi-aromatic polyester according to claim 1 or 2, characterized in that component a2) is selected from terephthalic acid, dimethyl terephthalate, bis (2-hydroxyethyl) terephthalate, bis (3-hydroxypropyl) terephthalate, bis (4-hydroxybutyl) terephthalate, isophthalic acid, dimethyl isophthalate, bis (2-hydroxyethyl) isophthalate, bis (3-hydroxypropyl) isophthalate, bis (4-hydroxybutyl) isophthalate, 2, 6-naphthalenedicarboxylic acid, dimethyl 2, 6-phthalate, 2, 7-naphthalenedicarboxylic acid, dimethyl 2, 7-phthalate, 3, 4' -diphenylether dicarboxylic acid, dimethyl 3, 4' -diphenylether dicarboxylate, 4' -diphenylether dicarboxylic acid, One or more of dimethyl 4,4' -diphenyletherdicarboxylate, dimethyl 3, 4' -phenylthioetherdicarboxylate, 4' -diphenylthioetherdicarboxylate, dimethyl 4,4' -phenylthioetherdicarboxylate, dimethyl 3, 4' -diphenylsulfonedicarboxylate, 4' -diphenylsulfonedicarboxylate, dimethyl 4,4' -diphenylsulfonedicarboxylate, 3, 4' -benzophenonedicarboxylic acid, dimethyl 3, 4' -benzophenonedicarboxylate, 4' -benzophenonedicarboxylic acid, dimethyl 4,4' -benzophenonedicarboxylate, 1, 4-naphthalenedicarboxylic acid, dimethyl 1, 4-naphthalenedicarboxylate, 4' -methylenebis (benzoic acid), 4' -methylenebis (dimethyl benzoate), or an ester derivative thereof or an anhydride derivative thereof, terephthalic acid or an ester derivative thereof or an anhydride derivative thereof is preferable.

4. Semi-aromatic polyester according to any of claims 1 to 3, characterized in that the recurring unit-CH in the third component C is based on the total molar amount of first component A₂CH₂CH₂CH₂The molar content of-O-is 0.05 to 0.30 mol%.

5. The semi-aromatic polyester according to any one of claims 1 to 4, further comprising a fourth component D, wherein the fourth component D is a compound having at least three functional groups, preferably a compound having three to six functional groups, more preferably one or more selected from the group consisting of tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerol, 1,3, 5-trimellitic acid, 1,2, 4-trimellitic anhydride, 1,2, 4, 5-pyromellitic acid and pyromellitic dianhydride, preferably trimethylolpropane, pentaerythritol or glycerol;

preferably, the content of the fourth component D is 0.01 to 5.0 mol%, and more preferably 0.02 to 2.0 mol%, based on the total molar amount of the first component a.

6. Semi-aromatic polyester according to any of claims 1 to 5, characterized in that it further contains a fifth component E, which is a chain extender; preferably, the fifth component E is selected from one or more of isocyanate, isocyanurate, peroxide, epoxide, oxazoline, oxazine, lactam, carbodiimide or polycarbodiimide containing 2 or more functional groups, preferably isocyanate containing 2 or more functional groups, and more preferably hexamethylene diisocyanate;

preferably, the content of the fifth component E is 0.01 to 5.0 mol% based on the total molar amount of the first component a.

7. The semi-aromatic polyester according to any one of claims 1 to 6, wherein the viscosity number of the semi-aromatic polyester is 100-;

preferably, the carboxyl content of the semi-aromatic polyester is 5 to 60mmol/kg, and more preferably 10 to 50 mmol/kg.

8. A process for preparing a semi-aromatic polyester according to any one of claims 1 to 7, comprising the steps of:

s1: mixing the first component A, the second component B and part of catalyst (if necessary, adding the fourth component D together), heating to 150-; wherein the molar consumption of the second component B is usually 1.1-3.0 times of that of the first component A, and the excessive second component B enters the esterification reactor after being recovered by a purification device connected with the esterification reactor;

s2: carrying out primary polycondensation reaction on the esterification product AB in the step S1 under the action of the residual catalyst, wherein the reaction temperature is 230-270 ℃ until the reaction product reaches the viscosity number of 20-60ml/g determined in a phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃ specified by GB/T17931-1999;

s3: transferring the product of the primary polycondensation reaction obtained in the step S2 into a final polymerization kettle, and continuously carrying out polycondensation reaction at the temperature of 220-270 ℃ until the reaction product reaches the viscosity number of 100-250ml/g determined in a phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃ specified in GB/T17931-1999, wherein the carboxyl content in the reaction product is 5-60mmol/kg, so as to obtain the semi-aromatic polyester;

preferably, in step S1, the purification apparatus is a combination of a process column and a short path distiller;

preferably, in step S1, the amount of the catalyst added is 0.001 to 1%, preferably 0.02 to 0.2% by weight of the final semi-aromatic polyester;

preferably, in step S1, the catalyst is added in an amount of 50-80 wt% of the total amount of the catalyst;

preferably, in the step S2, the reaction temperature is 240-260 ℃;

preferably, in step S2, the pressure is 0.1 to 0.5bar, preferably 0.2 to 0.4bar, at the beginning and 5 to 200mbar, preferably 10 to 100mbar, at the end;

preferably, in the step S2, the reaction time is 1-5 h;

preferably, the carboxyl group content of the product of the primary polycondensation reaction of step S2 is 10 to 60 mmol/kg;

preferably, in step S3, the reaction temperature for continuous polycondensation is 230 to 270 ℃;

preferably, in step S3, the pressure at the beginning is 0.2 to 5mbar, preferably 0.5 to 3 mbar;

preferably, in step S3, the reaction time is 30 to 90 minutes, preferably 40 to 80 minutes;

preferably, in step S3, the carboxyl content in the reaction product is 10-50 mmol/kg;

preferably, the catalyst is a tin compound, an antimony compound, a cobalt compound, a lead compound, a zinc compound, an aluminum compound, or a titanium compound, preferably a zinc compound, an aluminum compound, or a titanium compound, more preferably tetrabutyl orthotitanate or tetraisopropyl orthotitanate;

preferably, in step S3, a step of adding a passivating agent to the reaction system is further included;

preferably, the passivating agent is a phosphorus compound including phosphoric acid, phosphorous acid and esters thereof;

preferably, after the end of step S3, step S4 is carried out, the semi-aromatic polyester obtained in step S3 is fed into a twin-screw extruder, together with a fifth component E in an amount of 0.01-5.0 mol% (based on the total molar amount of the first component A), at a reaction temperature of 200 to 270 ℃ using a residence time of 0.5 to 15 minutes, to give a semi-aromatic polyester having a viscosity number of 150-.

9. A semi-aromatic polyester molding composition, characterized by comprising, in weight percent, the components:

5 to 95 wt% of the semi-aromatic polyester of any one of claims 1 to 7;

5-95 wt% of additives and/or other polymers;

0-70 wt% of reinforcing materials and/or fillers.

10. Use of a semi-aromatic polyester according to any one of claims 1 to 7 in the preparation of compostable degradation products, wherein the compostable degradation products are fibres, films or containers.

11. Use of the semi-aromatic polyester of any one of claims 1 to 7 in the manufacture of a straw.

Technical Field

The invention relates to the technical field of biodegradable polyester, in particular to semi-aromatic polyester and a preparation method and application thereof, and especially relates to semi-aromatic polyester with specific dimer (1, 4-butanediol) content and a preparation method and application thereof.

Background

The thermoplastic aromatic polyester widely used in industry and daily life has excellent thermal stability and mechanical property, convenient processing and low price. For example, polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) have been widely used in the manufacture of fibers, films, and containers. However, these aromatic polyesters are difficult to degrade after disposal, and no significant direct degradation of aromatic polyesters such as PET, PBT by microorganisms has been observed to date. In order to combine the excellent properties of aromatic polyesters, the skilled in the art has been devoted to the research of synthesizing aliphatic-aromatic copolyesters since the 80 th century, i.e. the introduction of aromatic chain segments into aliphatic polyesters ensures that the copolyesters have the excellent properties of aromatic polyesters and the biodegradability of the copolyesters.

For improving the color of polyesters, it is common practice in the industry to control the manner in which stabilizers are added during polycondensation, which has become a conventional technique in aromatic polyesters such as PET and PBT. For example, (Rieckmann, T.; Volker, S.,2.Poly (ethylene terephthalate) Polymerization-Mechanism, Catalysis, Kinetics, Mass Transfer and Reactor design. in model Polyesters: Chemistry and Technology of Polyesters and Polyesters, Scheirs, J.; Long, T.E., eds. John Wiley & Sons, Ltd.: Chichester, 2003; p 63.) indicate that the addition of phosphoric acid compounds (such as triphenyl phosphate, triphenyl phosphite, etc.) as stabilizers during the PET Polymerization greatly reduces the yellowing of PET; WO2018/219708a1 also indicates that aliphatic-aromatic copolyesters having a whiteness index according to ASTM E313-73 of at least 25 can be obtained by adding 0.03 to 0.04% by weight of a phosphorus compound in the polycondensation stage of the aliphatic-aromatic copolyester.

CN212560068U discloses a production system of biodegradable polyester. The esterification reaction kettle of the production system is connected with a process tower, water, tetrahydrofuran, excessive 1, 4-butanediol and the like generated in the esterification process enter the process tower to be rectified, the bottom of the process tower is heated by adopting a liquid heating medium, the recovered 1, 4-butanediol discharged from the bottom of the tower is sent back to a reflux port of the esterification kettle, and the recovered 1, 4-butanediol enters a reaction system through the reflux port to participate in the esterification reaction again. However, this simple process tower distillation only distills out water, tetrahydrofuran, etc. with low boiling point from the top of the process tower, and the rest materials all flow back to the esterification kettle from the bottom of the process tower, and these rest materials contain a large amount of by-products such as 1, 4-butanediol polymer, etc. which can participate in polymerization reaction after entering the esterification kettle, causing the deterioration of the properties of the subsequent aliphatic-aromatic polyester.

In summary, the influence of by-product impurities on the properties, especially the color, of copolyesters is not currently recognized by the person skilled in the art.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a semi-aromatic polyester with specific content of dimeric (1, 4-butanediol), a preparation method and application thereof.

The above object of the present invention is achieved by the following technical solutions:

in one aspect, the present invention provides a semi-aromatic polyester comprising repeating units derived from:

a first component a comprising, based on the total molar amount of the first component a:

a1)35 to 65 mol%, preferably 40 to 60 mol%, of at least one aliphatic dicarboxylic acid or an ester derivative thereof or an anhydride derivative thereof,

a2)35 to 65 mol%, preferably 40 to 60 mol%, of at least one aromatic dicarboxylic acid or an ester derivative thereof or an anhydride derivative thereof,

a second component B, 1, 4-butanediol,

a third component C, dimeric (1, 4-butanediol), molecular formula

HO-CH₂CH₂CH₂CH₂-O-CH₂CH₂CH₂CH₂-OH and, based on the total molar amount of the first component a, the repeating unit-CH in the third component C₂CH₂CH₂CH₂The molar content of-O-is 0.05 to 0.35 mol%.

The invention discovers that the repeating unit-CH in the third component C is added based on the total molar amount of the first component A₂CH₂CH₂CH₂The control of the molar content of-O-to 0.05 to 0.35 mol% is effective for improving the resin color of the semi-aromatic polyester without deterioration of the properties of the obtained copolyester.

As a specific selection example, said component a1) is selected from the group consisting of oxalic acid, dimethyl oxalate, malonic acid, dimethyl malonate, succinic acid, dimethyl succinate, methylsuccinic acid, glutaric acid, dimethyl glutarate, bis (2-hydroxyethyl) glutarate, bis (3-hydroxypropyl) glutarate, bis (4-hydroxybutyl) glutarate, 2-methylglutaric acid, 3-methylglutaric acid, adipic acid, dimethyl adipate, bis (2-hydroxyethyl) adipate, bis (3-hydroxypropyl) adipate, bis (4-hydroxybutyl) adipate, 3-methyladipic acid, 2,5, 5-tetramethyladipic acid, pimelic acid, suberic acid, azelaic acid, dimethyl azelate, sebacic acid, 1, 11-undecanedicarboxylic acid, sebacic acid, and mixtures thereof, 1, 10-decanedicarboxylic acid, undecanedioic acid, 1, 12-dodecanedicarboxylic acid, hexadecanedioic acid, eicosanedioic acid, tetracosanedioic acid, dimer acid or its ester derivatives or its anhydride derivatives, preferably one or more selected from succinic acid, adipic acid, sebacic acid, 1, 12-dodecanedicarboxylic acid or its ester derivatives or its anhydride derivatives, more preferably one or two selected from adipic acid, sebacic acid or its ester derivatives or its anhydride derivatives, most preferably adipic acid or its ester derivatives or its anhydride derivatives.

Meanwhile, the above ester derivatives of aliphatic dicarboxylic acids also fall within the category of component a1), preferably the ester derivatives of aliphatic dicarboxylic acids are selected from dialkyl esters of aliphatic dicarboxylic acids. The dialkyl esters are, for example, dimethyl, diethyl, di-n-propyl, diisopropyl, di-n-butyl, diisobutyl, di-tert-butyl, di-n-pentyl, diisopentyl or di-n-hexyl esters.

Meanwhile, the acid anhydride derivative formed from the above aliphatic dicarboxylic acid also falls within the category of the component a 1).

The aliphatic dicarboxylic acid or its ester derivative or its anhydride derivative described in the present invention may be used alone or in the form of a mixture of two or more.

In the present invention, the component a2) is selected from the group consisting of terephthalic acid, dimethyl terephthalate, bis (2-hydroxyethyl) terephthalate, bis (3-hydroxypropyl) terephthalate, bis (4-hydroxybutyl) terephthalate, isophthalic acid, dimethyl isophthalate, bis (2-hydroxyethyl) isophthalate, bis (3-hydroxypropyl) isophthalate, bis (4-hydroxybutyl) isophthalate, 2, 6-naphthalenedicarboxylic acid, dimethyl 2, 6-naphthalenedicarboxylate, 2, 7-naphthalenedicarboxylic acid, dimethyl 2, 7-naphthalenedicarboxylate, 3, 4 '-diphenyletherdicarboxylic acid, dimethyl 3, 4' -diphenyletherdicarboxylate, 4 '-diphenyletherdicarboxylic acid, dimethyl 4,4' -diphenyletherdicarboxylate, dimethyl-isophthalate, dimethyl-p-phthalate, One or more of 3, 4' -benzenesulfenedicarboxylic acid, dimethyl 3, 4' -benzenesulfenedicarboxylate, 4' -diphenylsulfenedicarboxylic acid, dimethyl 4,4' -benzenesulfenedicarboxylate, 3, 4' -diphenylsulfonedicarboxylic acid, dimethyl 3, 4' -diphenylsulfonedicarboxylate, 4' -diphenylsulfonedicarboxylic acid, dimethyl 4,4' -diphenylsulfonedicarboxylate, 3, 4' -benzophenonedicarboxylic acid, dimethyl 3, 4' -benzophenonedicarboxylic acid, 4' -benzophenonedicarboxylic acid, dimethyl 1, 4-naphthalenedicarboxylate, 4' -methylenebis (benzoic acid), 4' -methylenebis (dimethyl benzoate) or an ester derivative or an anhydride derivative thereof, terephthalic acid or an ester derivative thereof or an anhydride derivative thereof is preferable.

The third component C is dimeric (1, 4-butanediol) with the molecular formula

HO-CH₂CH₂CH₂CH₂-O-CH₂CH₂CH₂CH₂-OH and, based on the total molar amount of the first component a, the repeating unit-CH in the third component C₂CH₂CH₂CH₂The molar content of-O-is preferably from 0.05 to 0.30 mol%.

In the present invention, the semi-aromatic polyester further contains a fourth component D, if necessary, in which a compound having at least three functional groups, preferably a compound having three to six functional groups, is preferable. Preferably selected from: tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerol, 1,3, 5-trimellitic acid, 1,2, 4-trimellitic anhydride, 1,2, 4, 5-pyromellitic acid, and pyromellitic dianhydride, and more preferably trimethylolpropane, pentaerythritol, or glycerol.

The content of the fourth component D is 0.01 to 5.0 mol%, more preferably 0.02 to 2.0 mol%, based on the total molar amount of the first component A.

The semi-aromatic polyester can also comprise a fifth component E, and the fifth component E is a chain extender.

The chain extender is one or a mixture of more than 2 or more than 2 functional groups of isocyanate, isocyanurate, peroxide, epoxide, oxazoline, oxazine, lactam, carbodiimide or polycarbodiimide.

The isocyanate having 2 or more functional groups may be an aromatic isocyanate or an aliphatic isocyanate, and is preferably an aromatic diisocyanate or an aliphatic diisocyanate. Preferably, the aromatic diisocyanate is toluene 2, 4-diisocyanate, toluene 2, 6-diisocyanate, diphenylmethane 2, 2' -diisocyanate, diphenylmethane 2, 4' -diisocyanate, diphenylmethane 4,4' -diisocyanate, naphthalene 1, 5-diisocyanate or xylene diisocyanate.

More preferably, the aromatic diisocyanate is diphenylmethane 2, 2' -diisocyanate, diphenylmethane 2, 4' -diisocyanate or diphenylmethane 4,4' -diisocyanate.

Preferably, the aliphatic diisocyanate is preferably any linear or branched alkylene or cycloalkylene diisocyanate containing from 2 to 20 carbon atoms. More preferably from 3 to 12 carbon atoms. The aliphatic diisocyanate may be hexamethylene 1, 6-diisocyanate, isophorone diisocyanate or methylenebis (4-isocyanatocyclohexane). Most preferred is hexamethylene 1, 6-diisocyanate or isophorone diisocyanate.

The isocyanate containing 2 or more than 2 functional groups may also be tris (4-isocyanato-phenyl) methane with three rings.

Preferably, the isocyanurate containing 2 or more functional groups is an aliphatic isocyanurate derived from an alkylene diisocyanate or cycloalkylene diisocyanate having 2 to 20 carbon atoms, preferably 3 to 12 carbon atoms, such as isophorone diisocyanate or methylenebis (4-isocyanatocyclohexane). The alkylene diisocyanate may be a linear or branched compound. Particular preference is given to isocyanurates based on cyclic trimers, pentamers or higher oligomers of n-hexamethylene diisocyanate, such as hexamethylene 1, 6-diisocyanate.

Preferably, the peroxide having 2 or more functional groups is benzoyl peroxide, 1-di (t-butylperoxy) -3,3, 5-trimethylcyclohexane, 1-di (t-butylperoxy) methylcyclododecane, n-butyl 4, 4-di (butylperoxy) valerate, dicumyl peroxide, t-butyl peroxybenzoate, dibutyl peroxide, α -di (t-butylperoxy) diisopropylbenzene, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hexane, 2, 5-dimethyl-2, 5-di (t-butylperoxy) hex-3-yne, or t-butylperoxycumene.

Preferably, the epoxide compound having 2 or more functional groups is hydroquinone, diglycidyl ether, resorcinol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, diglycidyl terephthalate, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, dimethyl diglycidyl phthalate, phenylene diglycidyl ether, ethylene diglycidyl ether, trimethylene diglycidyl ether, tetramethylene diglycidyl ether, hexamethylene diglycidyl ether, sorbitol diglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, hydrogenated bisphenol A diglycidyl ether, 1, 6-hexanediol diglycidyl ether, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, dimethyl diglycidyl phthalate, phenylene diglycidyl ether, ethylene diglycidyl ether, trimethylene diglycidyl ether, tetramethylene diglycidyl ether, hexamethylene diglycidyl ether, sorbitol diglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycidyl polyglycidyl ether, or mixtures thereof, Resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, or polybutylene glycol diglycidyl ether.

The epoxide containing 2 or more than 2 functional groups is also preferably a copolymer based on styrene, acrylate and/or methacrylate and comprising an epoxy group, preferably glycidyl methacrylate. Compounds which have proven advantageous are copolymers in which the proportion of glycidyl methacrylate in the copolymer is greater than 20% by weight, more preferably greater than 30% by weight, and more preferably greater than 50% by weight. The epoxy equivalent weight in these copolymers is preferably from 150 to 3000 g/equivalent, more preferably from 200 to 500 g/equivalent. The weight average molecular weight Mw of the copolymer is preferably from 2000 to 25000, more preferably from 3000 to 8000. The number average molecular weight Mn of the copolymer is preferably from 400 to 6000, more preferably from 1000 to 4000. The polydispersity index (Q ═ Mw/Mn) is preferably from 1.5 to 5.

The oxazoline or oxazine having 2 or more functional groups is preferably a bisoxazoline or a bisoxazine, and the bridging moiety thereof is a single bond, (CH)₂) z-alkylene, wherein z ═ 2, 3 or 4, such as methylene, ethyl-1, 2-diyl, propyl-1, 3-diyl, propyl-1, 2-diyl or phenylene. Specifically, the bisoxazoline is 2, 2' -bis (2-oxazoline), bis (2-oxazoline) methane, 1, 2-bis (2-oxazoline) ethane, 1, 3-bis (2-oxazoline) propane, 1, 4-bis (2-oxazoline) butane, 2' -bis (2-oxazoline), 2' -bis (oxazoline)(4-methyl-2-oxazoline), 2, 2' -bis (4, 4' -dimethyl-2-oxazoline), 2, 2' -bis (4-ethyl-2-oxazoline), 2, 2' -bis (4, 4' -diethyl-2-oxazoline), 2, 2' -bis (4-propyl-2-oxazoline), 2, 2' -bis (4-butyl-2-oxazoline), 2, 2' -bis (4-hexyl-2-oxazoline), 2, 2' -bis (4-phenyl-2-oxazoline), 2, 2' -bis (4-cyclohexyl-2-oxazoline), 2, 2' -bis (4-benzyl-2-oxazoline), 2,2 '-p-phenylenebis (4-methyl-2-oxazoline), 2' -p-phenylenebis (4,4 '-dimethyl-2-oxazoline), 2' -m-phenylenebis (4-methyl-2-oxazoline), 2 '-m-phenylenebis (4, 4' -dimethyl-2-oxazoline), 2 '-hexamethylenebis (2-oxazoline), 2' -octamethylenebis (2-oxazoline), 2 '-decamethylenebis (2-oxazoline), 2' -ethylenebis (4-methyl-2-oxazoline), 2 '-tetramethylenebis (4, 4' -dimethyl-2-oxazoline), 2,2 '-9, 9' -diphenoxyethanedibis (2-oxazoline), 2 '-cyclohexylenedi (2-oxazoline) or 2, 2' -diphenylene (2-oxazoline).

Specifically, the dioxazine is 2, 2' -bis (2-dioxazine), bis (2-dioxazinyl) methane, 1, 2-bis (2-dioxazinyl) ethane, 1, 3-bis (2-dioxazinyl) propane, 1, 4-bis (2-dioxazinyl) butane, 1, 4-bis (2-dioxazinyl) benzene, 1, 2-bis (2-dioxazinyl) benzene or 1, 3-bis (2-dioxazinyl) benzene.

More preferably 1, 4-bis (2-oxazolinyl) benzene, 1, 2-bis (2-oxazolinyl) benzene or 1, 3-bis (2-oxazolinyl) benzene.

The carbodiimide or polycarbodiimide having 2 or more functional groups is preferably N, N '-di-2, 6-diisopropylphenylcarbodiimide, N' -di-o-tolylcarbodiimide, N '-diphenylcarbodiimide, N' -dioctyldecylcarbodiimide, N '-di-2, 6-dimethylphenylcarbodiimide, N-tolyl-N' -cyclohexylcarbodiimide, N '-di-2, 6-di-tert-butylphenyl carbodiimide, N-tolyl-N' -phenylcarbodiimide, N '-di-p-nitrophenylcarbodiimide, N' -di-p-aminophenylcarbodiimide, N, n ' -di-p-hydroxyphenylcarbodiimide, N ' -dicyclohexylcarbodiimide, N ' -di-p-tolylcarbodiimide, p-phenylenebis-di-o-tolylcarbodiimide, p-phenylenebis-dicyclohexylcarbodiimide, hexamethylenebisdicyclohexylcarbodiimide, 4' -dicyclohexylmethanecarbodiimide, ethylenebisdiphenylcarbodiimide, N ' -phenylmethyl-carbodiimide, N-octadecyl-N ' -phenylcarbodiimide, N-benzyl-N ' -phenylcarbodiimide, N-octadecyl-N ' -tolylcarbodiimide, N-cyclohexyl-N ' -tolylcarbodiimide, N-phenyl-N ' -tolylcarbodiimide, N-octadecyl-N ' -tolylcarbodiimide, N-cyclohexylcarbodiimide, N-phenyl-N ' -tolylcarbodiimide, N ' -tolylcarbodiimide, N ' -diphenylcarbodiimide, N-tolylcarbodiimide, N ' -tolylcarbodiimide, N, p-tolylcarbodiimide, N, p, N-benzyl-N '-tolylcarbodiimide, N' -di-o-ethylphenylcarbodiimide, N '-di-p-ethylphenylcarbodiimide, N' -di-o-isopropylphenylcarbodiimide, N '-di-p-isopropylphenylcarbodiimide, N' -di-o-isobutylphenylcarbodiimide, N '-di-p-isobutylphenylcarbodiimide, N' -di-2, 6-diethylphenylcarbodiimide, N '-di-2-ethyl-6-isopropylphenylcarbodiimide, N' -di-2-isobutyl-6-isopropylphenylcarbodiimide, 4, 6-trimethylphenylcarbodiimide, N '-di-2, 4, 6-triisopropylphenylcarbodiimide, N' -di-2, 4, 6-triisobutylphenylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, di-beta-naphthylcarbodiimide or di-tert-butylcarbodiimide.

Preferably, the content of the fifth component E is 0.01 to 5 mol% based on the total molar amount of the first component A.

Preferably, the semi-aromatic polyester has a viscosity number of 100-.

Preferably, the carboxyl content of the semi-aromatic polyester is 5 to 60mmol/kg, and more preferably 10 to 50 mmol/kg.

In another aspect, the present invention also provides a method for preparing the above semi-aromatic polyester, comprising the steps of:

s1: mixing the first component A, the second component B and part of catalyst (if necessary, adding the fourth component D together), heating to 150-; wherein the molar consumption of the second component B is usually 1.1-3.0 times of that of the first component A, and the excessive second component B enters the esterification reactor after being recovered by a purification device connected with the esterification reactor;

s2: carrying out primary polycondensation reaction on the esterification product AB in the step S1 under the action of the residual catalyst, wherein the reaction temperature is 230-270 ℃ until the reaction product reaches the viscosity number of 20-60ml/g determined in a phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃ specified by GB/T17931-1999;

s3: and (3) transferring the product of the primary polycondensation reaction obtained in the step S2 into a final polymerization kettle, and continuously carrying out polycondensation reaction at the temperature of 220-270 ℃ until the reaction product reaches the viscosity number of 100-250ml/g determined in a phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃ specified in GB/T17931-1999, wherein the carboxyl content in the reaction product is 5-60mmol/kg, so as to obtain the semi-aromatic polyester.

Preferably, in step S1, 0.001 to 1% of a catalyst based on the weight of the final semi-aromatic polyester is added in the preparation of the AB esterification product. Preferably, the amount of the catalyst added is 0.02 to 0.2% by weight of the final semi-aromatic polyester. The amount of catalyst added in step S1 is generally 50-80 wt% of the total amount of catalyst used. The subsequent processing process can be more stable by controlling the adding amount of the catalyst. Further, the catalyst may be a tin compound, an antimony compound, a cobalt compound, a lead compound, a zinc compound, an aluminum compound or a titanium compound, more preferably a zinc compound, an aluminum compound or a titanium compound, and most preferably a titanium compound. Titanium compounds such as tetrabutyl orthotitanate or tetraisopropyl orthotitanate have the advantage over other compounds of low toxicity of residual amounts remaining in the product or downstream products. This property is particularly important in biodegradable polyesters, since they can enter the environment directly in the form of compost bags or mulch films.

Preferably, in step S1, the purification apparatus associated with the esterification reactor is a combination of a process column and a short path distiller.

Molecular distillation is a distillation process operated under high vacuum where the mean free path of the vapor molecules is greater than the distance between the evaporation and condensation surfaces, thereby allowing the separation of liquid mixtures by differences in the evaporation rates of the components of the feed solution.

The short path distiller is designed according to the principle of molecular distillation, is a model for simulating molecular distillation, and is called as a short path distiller because the heating surface and the cooling surface are very close to each other and have very small resistance. The vaporized vapor phase can be instantly liquefied and the volume can be reduced due to the function of the built-in condenser, so that the high vacuum in the equipment can be maintained. The operation vacuum of the short-path distiller can reach 0.1Pa (absolute pressure), which can not be reached by other evaporation and distillation equipment, so the short-path distiller is particularly suitable for materials with high boiling point under normal pressure and difficult separation by a common separation method, and has been successfully experienced in a plurality of industries as a novel liquid-liquid separation equipment.

The short path distiller can be an SPD type short path distiller of Suntangless chemical mechanical Co., Ltd. (http:// www.wxhengyi.com/index. asp).

The process tower mainly separates low boiling point substances such as tetrahydrofuran, water and other byproducts, and the low boiling point substances flow out of the tower top and then enter a tetrahydrofuran purification device; high boiling point substances such as 1, 4-butanediol and other byproducts flow out of the bottom of the process tower and enter an SPD type short-path distiller, and are recovered and enter an esterification reactor after being purified by the short-path distiller.

In step S2, the remaining amount of catalyst may be added in step S2, if necessary. In step S2, the reaction temperature is more preferably 240 to 260 ℃. In step S2, the pressure at the beginning is typically set to 0.1 to 0.5bar, preferably 0.2 to 0.4bar, and the pressure at the end of S2 is typically set to 5 to 200mbar, more preferably 10 to 100 mbar. In step S2, the reaction time is generally 1-5 h, and after the reaction time, the pre-polyester with viscosity number of 20-60ml/g determined in phenol/o-dichlorobenzene solution with weight ratio of 1:1 in 25 + -0.05 ℃ constant temperature water bath according to GB/T17931-1999 can be produced. The carboxyl content of the resulting pre-polyester after the S2 reaction is generally in the range from 10 to 60 mmol/kg.

In step S3, a passivating agent may be added to the reaction system, if desired. Useful phlegmatising agents are typically phosphorus compounds including phosphoric acid, phosphorous acid and esters thereof. When a highly active titanium catalyst is used in the system, a passivating agent is generally added in step S3.

In step S3, the reaction temperature for continuous polycondensation is preferably 230 to 270 ℃. In step S3, the pressure at the start is generally controlled to be 0.2 to 5mbar, more preferably 0.5 to 3 mbar. The reaction time for the continuous polycondensation is preferably 30 to 90 minutes, more preferably 40 to 80 minutes. The carboxyl content of the semi-aromatic polyester after the reaction of S3 is 5-60mmol/kg, preferably 10-50 mmol/kg.

If necessary, after the end of step S3, step S4 is carried out, and the semi-aromatic polyester obtained in step S3 is fed into a twin-screw extruder together with the fifth component E in an amount of 0.01 to 5.0 mol% (based on the total molar amount of the first component A) at a reaction temperature of 200 to 270 ℃ for a residence time of 0.5 to 15 minutes to obtain a semi-aromatic polyester having a viscosity number of 150-.

In a further aspect, the invention also provides the use of the above semi-aromatic polyester in the preparation of compostable degraded products which may be fibres, films or containers and the like.

The invention also provides application of the semi-aromatic polyester in preparation of a straw. The semi-aromatic polyester can be blended and modified with polylactic acid (PLA) and the like to be used as a manufacturing material of the suction pipe, and the suction pipe is in contact with liquid, so that the suction pipe is required to have certain hydrolysis resistance, but the hydrolysis resistance cannot be too high in consideration of the requirement of degradation, otherwise, the degradation period is too long. According to practical applications, the degradation performance is evaluated by using a 30-day weight retention rate test, the 30-day weight retention rate is generally preferably in the range of 50-60%, and in this range, the higher the value, the better the degradation performance. The weight retention rate is over 65 percent in 30 days, and the degradation performance is too poor; below 45%, the degradation is too rapid. In still another aspect, the present invention also provides a semi-aromatic polyester molding composition comprising the following components in parts by weight:

5 to 95 wt% of the above semi-aromatic polyester;

5-95 wt% of additives and/or other polymers;

0-70 wt% of reinforcing materials and/or fillers.

As a specific option, the additive and/or other polymer may be at least one or more components selected from the group consisting of aliphatic polyesters, polycaprolactone, starch, cellulose, polyhydroxyalkanoates, and polylactic acid.

Compared with the prior art, the invention has the following beneficial effects:

the invention provides a semi-aromatic polyester, a preparation method and application thereof, based on the total molar weight of diacid, a repeating unit-CH in dimer (1, 4-butanediol)₂CH₂CH₂CH₂The molar content of-O-is controlled to 0.05 to 0.35 mol%, preferably 0.05 to 0.30 mol%, which is effective for improving the resin color of the semi-aromatic polyester without degrading the properties of the copolyester.

Drawings

FIG. 1 shows PBAT obtained in example 2 measured with AV 500 NMR spectrometer from Bruker¹H NMR；

FIG. 2 shows the key peaks of the repeating unit of dimer (1, 4-butanediol) in PBAT obtained in example 8.1¹H NMR；

FIG. 3 is a schematic diagram of an esterification reactor in combination with a process column and a short path distiller in accordance with an embodiment of the present invention;

FIG. 4 is a schematic view of a conventional esterification reactor connected to a primary process column apparatus;

FIG. 5 shows the CH linkage to the ether linkage oxygen atom of the polymerization product obtained in example 8.6 after addition of poly (1, 4-butanediol) having a molecular weight of 1000₂Having a peak near the upper hydrogen atom¹H NMR。

Detailed Description

Unless otherwise specified, the raw materials, reagents and solvents used in the present invention were purchased commercially and were not subjected to any treatment. The present invention is described in further detail with reference to the following examples, but the embodiments of the present invention are not limited to the examples, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and they are included in the scope of the present invention. In the present specification, "part" and "%" represent "part by mass" and "% by mass", respectively, unless otherwise specified.

The test method comprises the following steps:

the purity test methods of fresh 1, 4-butanediol, crude 1, 4-butanediol recovery and high-purity 1, 4-butanediol recovery comprise the following steps:

the purity of the 1, 4-butanediol is tested by referring to the industrial 1, 4-butanediol of the national standard GB/T24768-2009.

Wherein, the purity of the fresh 1, 4-butanediol in all the examples and the comparative examples is the same, and the purity is more than or equal to 99.7 percent, which is purchased from Xinjiang Meike chemical Co. Other materials such as terephthalic acid, adipic acid, sebacic acid, glycerin, tetrabutyl orthotitanate, phosphorous acid, and the like are commercially available.

Test of the content of the third component C in the semi-aromatic polyester (taking the poly (butylene adipate terephthalate) (PBAT) obtained in example 2 as an example):

20mg of a semi-aromatic polyester sample was dissolved in 0.6ml of deuterated chloroform, and the solution was measured at room temperature using a Bruker AV 500 NMR spectrometer¹H NMR, nominal chloroform solvent peak 7.26 ppm.

Reference documents: chen, x.; chen, w.; zhu, g.; huang, f.; zhang, J., Synthesis,1H-NMR spectroscopy, and biodaradation dehavisor of aliphatic-aromatic random copolymer.J.appl.Polymer.Sci.2007, 104(4):2643-2649. it is known that 4 hydrogen atoms in the benzene ring in the terephthalic acid repeating unit occur in the vicinity of 8.10 ppm; two CH's adjacent to the carbonyl group in the repeating unit of adipic acid₂The 4 hydrogen atoms of the unit occur in the vicinity of 2.33 ppm. As shown in fig. 1. Thus, the molar content of the diacid component can be determined by the integrated area of the two peaks (I) at 8.10ppm and 2.33ppm_TAnd I_A) Represents:

molar terephthalic acid content in PBAT ═ I_T/(I_T+I_A)×100％

Adipic acid molar content in PBATAmount ═ I_A/(I_T+I_A)×100％

Reference documents: miles, w.h.; ruddy, d.a.; tinorgah, s.; geisler, R.L., acrylic polymerization of Tetrahydrofuran catalysis by ray-Earth triflates, Synth, Commin.2004, 34(10) 1871-1880, product of Dimerization of (1, 4-butanediol) with benzoic acid and acetic acid¹The H NMR chemical shifts (in ppm on the carbon atom corresponding to the formula) are shown below:

with reference to substances 1a and 1d above¹H NMR showed that the copolymerization of dimeric (1, 4-butanediol) with adipic acid (analogous to 1a) and terephthalic acid (analogous to 1d) has CH attached to the ether linkage oxygen atom₂The hydrogen atoms of the units occur in the vicinity of 3.40 and 3.48 ppm.

To further validate the dimerization of (1, 4-butanediol) in the PBAT copolyester¹The peak position of H NMR was determined from the PBAT copolyester obtained after deliberate addition of dimer (1, 4-butanediol) as in example 8.1¹H NMR to give dimeric (1, 4-butanediol) polymerized to PBAT copolyester with CH attached to the ether linkage oxygen atom₂Having a peak near the upper hydrogen atom¹The H NMR is shown in FIG. 2, which indicates that the peaks around 3.40 and 3.48ppm do match our above predictions.

From FIG. 2, it can be calculated that the repeating unit-CH in the third component C is based on the total molar amount of the first component A (diacid)₂CH₂CH₂CH₂Molar content X of-O-_CComprises the following steps:

wherein the content of the first and second substances,

I₁and I_1'is-CH attached to an ether linkage oxygen atom on a dimeric (1, 4-butanediol) repeat unit adjacent to terephthalic acid₂-integrated area of the upper 2 hydrogen atom peaks;

I₂and I_2'is-CH linked to an ether linkage oxygen atom on a dimeric (1, 4-butanediol) repeat unit adjacent to adipic acid₂-integrated area of the upper 2 hydrogen atom peaks;

I_Tis the integral area of 4 hydrogen atoms on a benzene ring of a terephthalic acid repeating unit;

I_A2-CH linking adipic acid repeat units to carbonyl groups₂-upper 4 hydrogen atoms integrated area;

repeat units-CH in the third component C in other PBAT₂CH₂CH₂CH₂The molar content of-O-is likewise obtained in a similar manner.

Viscosity number of semi-aromatic polyester:

the sample concentration was 5mg/ml, as determined in a phenol/o-dichlorobenzene solution in a weight ratio of 1:1 in a thermostatic water bath at 25. + -. 0.05 ℃ according to GB/T17931-1999.

Color of semi-aromatic polyester: the cut and dried samples were taken and tested according to GB/T14190-20175.5.2 method B (drying method). The test gives the Hunter Lab colour system L, a, b values, defining the Hunter whiteness:

WH＝100-[(100-L)²+a²+b²]^1/2

the greater the Hunter whiteness value, the better the sample color.

Carboxyl group content:

the acid number AN (mg KOH/g) was first determined in accordance with DIN EN 12634, month 10, 1998, and the carboxyl group content (mmol/kg) ═ AN/56. times.10³. The solvent mixture used comprised 1 part by volume of DMSO, 8 parts by volume of isopropanol, and 7 parts by volume of toluene, the solvent volume being 100 ml. Heating 3-6g of semi-aromatic polyester to 70 ℃ to completely dissolve all polymers into a clear solution, and keeping the temperature of the solution at 60-70 ℃ during titration to avoid polymer precipitation. Tetrabutylammonium hydroxide is selected as the titration solution, and highly toxic tetramethylammonium hydroxide is avoided. At the same time, in order to avoid the mixed solvent absorbing CO in the air₂Thereby influencing the volume of the titration solution consumed by the blank solvent, heating the blank solvent to 70 ℃ when the volume of the titration solution consumed by the blank solvent is tested, keeping the temperature for 0.5h, and then carrying outTitration of the empty solvent was performed.

30-day weight retention:

the biodegradation test of the semi-aromatic polyester is tested with reference to GB/T19277-2003. The semi-aromatic polyester sample is first pressed into a film with a thickness of 0.10mm and then cut into a sample piece with a thickness of 1.2cm 2.0cm, and the sample weight is recorded as a₀. Then embedding the sample piece into compost soil and putting the compost soil into a thermostat, wherein the compost soil is urban garbage compost after being aerated and sieved for 56-70 days, the experimental temperature is constant at (58 +/-2) DEG C, the compost sample piece is taken out after 30 days, the sample piece is cleaned, dried and weighed, and the weight of the sample is recorded as a₁. The weight retention ratio of 30 days is a₁/a₀X 100%. The higher the 30-day weight retention rate, the more difficult the material is to degrade, and the lower the 30-day weight retention rate, the faster the material degrades. The 30-day weight retention is generally preferred in the range of 50 to 60% depending on the practical application, and in this range, the higher the value, the better. The weight retention rate is over 65 percent in 30 days, and the degradation performance is too poor; below 45%, the degradation is too rapid.

Example 1

S1: using a combination device of an esterification reactor and a connecting process tower and a short-path distiller shown in fig. 3, 437kg/h of terephthalic acid, 437kg/h of adipic acid, 760kg/h of fresh 1, 4-butanediol and 253kg/h of recovered high-purity 1, 4-butanediol (purity 99.2% from the bottom of the short-path distiller in fig. 3), 1.15kg/h of glycerol and 0.506kg/h of tetrabutyl orthotitanate are physically mixed at normal temperature in the esterification reactor, and then the mixture is subjected to esterification reaction at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.276kg/h tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and the majority of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches 23ml/g of viscosity number determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.23kg/h phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products were distilled off and then pelletized with an underwater pelletizer and then dried to give the final polyester product. The performance results are shown in Table 1.

Example 2

S1: using a combination device of an esterification reactor shown in fig. 3 and connecting a process tower and a short-path distiller, 437kg/h of terephthalic acid, 437kg/h of adipic acid, 760kg/h of fresh 1, 4-butanediol, 25kg/h of recycled crude 1, 4-butanediol (purity 98.5% from the bottom of the process tower in fig. 3), 228kg/h of recycled high-purity 1, 4-butanediol (purity 99.3% from the bottom of the short-path distiller in fig. 3), 1.15kg/h of glycerol and 0.506kg/h of tetrabutyl orthotitanate are physically mixed in the esterification reactor at normal temperature, and then the mixture is subjected to esterification reaction at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.276kg/h tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and the majority of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches the viscosity number of 26ml/g determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.23kg/h phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products were distilled off and then pelletized with an underwater pelletizer and then dried to give the final polyester product. The performance results are shown in Table 1.

Example 3

S1: using a combination device of an esterification reactor shown in fig. 3 and connecting a process tower and a short-path distiller, 437kg/h of terephthalic acid, 437kg/h of adipic acid, 760kg/h of fresh 1, 4-butanediol, 51kg/h of recycled crude 1, 4-butanediol (purity 98.6% from the bottom of the process tower in fig. 3), 202kg/h of recycled high-purity 1, 4-butanediol (purity 99.3% from the bottom of the short-path distiller in fig. 3), 1.15kg/h of glycerol and 0.506kg/h of tetrabutyl orthotitanate are physically mixed in the esterification reactor at normal temperature, and then the mixture is subjected to esterification reaction at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.276kg/h tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and the majority of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches the viscosity number of 29ml/g determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.23kg/h phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products were distilled off and then pelletized with an underwater pelletizer and then dried to give the final polyester product. The performance results are shown in Table 1.

Example 4

S1: using a combination device of an esterification reactor shown in fig. 3 and connecting a process tower and a short-path distiller, 437kg/h of terephthalic acid, 437kg/h of adipic acid, 760kg/h of fresh 1, 4-butanediol, 101kg/h of recovered crude 1, 4-butanediol (purity 98.7% from the bottom of the process tower in fig. 3), 152kg/h of recovered high-purity 1, 4-butanediol (purity 99.4% from the bottom of the short-path distiller in fig. 3), 1.15kg/h of glycerol and 0.506kg/h of tetrabutyl orthotitanate are physically mixed in the esterification reactor at normal temperature, and then the mixture is subjected to esterification reaction at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.276kg/h tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and the majority of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches the viscosity number of 21ml/g determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.23kg/h phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products were distilled off and then pelletized with an underwater pelletizer and then dried to give the final polyester product. The performance results are shown in Table 1.

Example 5

S1: using a combined device of an esterification reactor and a short path distiller shown in fig. 3 to connect a process tower and the short path distiller, 437kg/h of terephthalic acid, 605kg/h of sebacic acid, 760kg/h of fresh 1, 4-butanediol, 25kg/h of recycled crude 1, 4-butanediol (purity 98.4% from the bottom of the process tower in fig. 3), 228kg/h of recycled high-purity butanediol (purity 99.4% from the bottom of the short path distiller in fig. 3), 1.15kg/h of glycerol and 0.506kg/h of tetrabutyl orthotitanate are physically mixed at normal temperature in the esterification reactor, and then the mixture is subjected to esterification reaction at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.276kg/h tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and the majority of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches the viscosity number of 30ml/g determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.23kg/h phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products were distilled off and then pelletized with an underwater pelletizer and then dried to give the final polyester product. The performance results are shown in Table 1.

Example 6

S1: using a combination device of an esterification reactor shown in fig. 3 and connecting a process tower and a short-path distiller, 437kg/h of terephthalic acid, 437kg/h of adipic acid, 760kg/h of fresh 1, 4-butanediol, 25kg/h of recycled crude 1, 4-butanediol (purity 98.7% from the bottom of the process tower in fig. 3), 228kg/h of recycled high-purity 1, 4-butanediol (purity 99.2% from the bottom of the short-path distiller in fig. 3) and 0.506kg/h of tetrabutyl orthotitanate are physically mixed in the esterification reactor at normal temperature, and then the mixture is subjected to esterification reaction at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.276kg/h tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and the majority of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches the viscosity number of 26ml/g determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.23kg/h phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products were distilled off and then pelletized with an underwater pelletizer and then dried to give the final polyester product. The performance results are shown in Table 1.

Example 7

S1: using a combination device of an esterification reactor shown in fig. 3 and connecting a process tower and a short-path distiller, 437kg/h of terephthalic acid, 325kg/h of adipic acid, 656kg/h of fresh 1, 4-butanediol, 22kg/h of recycled crude 1, 4-butanediol (purity 98.6% from the bottom of the process tower in fig. 3), 197kg/h of recycled high-purity 1, 4-butanediol (purity 99.3% from the bottom of the short-path distiller in fig. 3), 0.994kg/h of glycerol and 0.446kg/h of tetrabutyl orthotitanate are physically mixed in the esterification reactor at normal temperature, and then the mixture is subjected to esterification reaction at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.243kg/h tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and most of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches the viscosity number of 29ml/g determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.20kg/h of phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products being distilled off and then pelletized with an underwater pelletizer and dried to give the final polyester product. The performance results are shown in Table 1.

Comparative example 1

S1: using a traditional single-process tower esterification reactor shown in figure 4, 437kg/h terephthalic acid, 437kg/h adipic acid, 760kg/h fresh 1, 4-butanediol, 253kg/h recycled crude 1, 4-butanediol (purity 98.5%), 1.15kg/h glycerol and 0.506kg/h tetrabutyl orthotitanate are physically mixed in the esterification reactor at normal temperature, and then the mixture is subjected to esterification reaction at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.276kg/h tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and the majority of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches 22ml/g of viscosity number determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.23kg/h phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products were distilled off and then pelletized with an underwater pelletizer and then dried to give the final polyester product. The performance results are shown in Table 1.

Comparative example 2

S1: a conventional single process column esterification reactor as shown in fig. 4 was used while the reflux valve in the lower portion of the process column was closed to avoid recycling 1, 4-butanediol into the esterification reactor. Physically mixing 437kg/h of terephthalic acid, 437kg/h of adipic acid, 1013kg/h of fresh 1, 4-butanediol (all fresh 1, 4-butanediol is used, and 1, 4-butanediol is not recovered), 1.15kg/h of glycerol and 0.506kg/h of tetrabutyl orthotitanate in an esterification reactor at normal temperature, and then carrying out esterification reaction on the mixture at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.276kg/h tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and the majority of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches the viscosity number of 24ml/g determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.23kg/h phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products were distilled off and then pelletized with an underwater pelletizer and then dried to give the final polyester product. The performance results are shown in Table 1.

Comparative example 3

S1: using a combination device of an esterification reactor shown in fig. 3 and connecting a process tower and a short-path distiller, 437kg/h of terephthalic acid, 165kg/h of adipic acid, 508kg/h of fresh 1, 4-butanediol, 17kg/h of recycled crude 1, 4-butanediol (purity 98.5% from the bottom of the process tower in fig. 3), 152kg/h of recycled high-purity 1, 4-butanediol (purity 99.3% from the bottom of the short-path distiller in fig. 3), 0.77kg/h of glycerol and 0.337kg/h of tetrabutyl orthotitanate are physically mixed in the esterification reactor at normal temperature, and then the mixture is subjected to esterification reaction at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.184kg/h tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and the majority of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches the viscosity number of 29ml/g determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.153kg/h of phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products being distilled off and then pelletized with an underwater pelletizer and then dried to give the final polyester product. The performance results are shown in Table 1.

Comparative example 4

S1: using a combined device of an esterification reactor connected with a process tower and a short path distiller shown in fig. 3, 437kg/h of terephthalic acid, 897kg/h of adipic acid, 1185kg/h of fresh 1, 4-butanediol, 40kg/h of recovered crude 1, 4-butanediol (purity 98.4% from the bottom of the process tower in fig. 3), 356kg/h of recovered high-purity 1, 4-butanediol (purity 99.5% from the bottom of the short path distiller in fig. 3), 1.791kg/h of glycerol and 0.796kg/h of tetrabutyl orthotitanate are physically mixed in the esterification reactor at normal temperature, and then the mixture is subjected to esterification reaction at 240 ℃ and 0.45bar for 60-120 minutes to obtain an esterification product AB;

s2: passing the esterification product AB through a static mixer, feeding into a vertical stirring full-mixing reactor, heating to 260 deg.C, and pressurizing at 0.3 bar; 0.434kg/h of tetrabutyl orthotitanate are introduced into the reactor, the pressure is reduced to 100mbar and the majority of the excess 1, 4-butanediol is distilled off. The reaction time is 60-120 minutes, when the reaction product reaches 23ml/g of viscosity number determined in phenol/o-dichlorobenzene solution with the weight ratio of 1:1 in a constant-temperature water bath at 25 +/-0.05 ℃;

s3: 0.36kg/h phosphorous acid was added to the reaction mixture while the reaction mixture was transferred to a final polymerization reactor and polycondensed at a temperature of 260 ℃ and a pressure of 1mbar for a further 60-80 minutes, the remaining excess 1, 4-butanediol and other by-products were distilled off and then pelletized with an underwater pelletizer and then dried to give the final polyester product.

The performance results are shown in Table 1.

From example 1 to example 4, it can be seen that the repeating unit-CH in the third component C₂CH₂CH₂CH₂When the molar content of-O-is 0.05-0.30 mol%, the whiteness is higher, and the weight retention rate is better in 30 days; in example 5, the degradation rate is relatively fast (the weight retention rate is reduced after 30 days) when the sebacic acid replaces the adipic acid; example 6 has no glycerin, so that the viscosity number and the weight retention rate of 30 days are reduced; example 7 has a higher terephthalic acid content and an increased 30 day weight retention, but is still within a commercially acceptable range.

The resin obtained in comparative example 1, in which the repeating unit-CH in the third component C is₂CH₂CH₂CH₂The molar content of O-is out of range, resulting in a poor color of the resin; likewise, the resin obtained in comparative example 2 has the repeating unit-CH of the third component C₂CH₂CH₂CH₂Too low molar content of-O-, the 30-day weight retention is too high although excellent color resin is obtained, and the excess 1, 4-butanediol cannot be recovered, the production line running cost is high, and it has no commercial value; comparative example 3 the terephthalic acid content was too high and the resin degradation performance was poor (the 30-day weight retention rate was too high); comparative example 4 to benzeneToo low a dicarboxylic acid content results in too rapid resin degradation (too low a 30 day weight retention).

Example 8

As the recovered 1, 4-butanediol may contain various products after the polymerization of 1, 4-butanediol, such as dimeric (1, 4-butanediol) and poly (1, 4-butanediol), the relationship between the color of the PBAT resin and the color of the PBAT resin is further verified. The relationship between dimeric (1, 4-butanediol) and poly (1, 4-butanediol) and resin color was investigated. The 1, 4-butanediol starting materials used in this example were all the same and were fresh butanediol having a purity of 99.7% or more.

The reference (Alexander, K.; Schniepp, L.E.,4,4' -Dichlorodibutyl Ether and its Derivatives from tetrahydrofuran.J.Am.chem.Soc.1948,70(5):1839-1842.) synthesizes dimeric (1, 4-butanediol); poly (1, 4-butanediol) with molecular weights of 1000 and 650 was purchased from Sigma-Aldrich.

Example 8.1

Under the protection of high-purity nitrogen, putting 2.36kg of terephthalic acid, 2.36kg of adipic acid, 4.38kg of 1, 4-butanediol, 50g of dimer (1, 4-butanediol), 6.2g of glycerol and 4.2g of n-butyl titanate into a reaction kettle, heating to 220-240 ℃, and keeping the temperature constant for 120 min. Then, 1.25g of phosphorous acid was charged thereinto. Reducing the pressure in the reaction kettle to be below 50Pa within 30-60 minutes, and reacting for 60-120min at 220-260 ℃. Stopping stirring, filling high-purity nitrogen into the reaction kettle, extruding the resin out of the reaction kettle, and performing water-cooling granulation to obtain the polyester product. The performance results are shown in Table 2.

Example 8.2Under the protection of high-purity nitrogen, 2.36kg of terephthalic acid, 2.36kg of adipic acid, 4.38kg of 1, 4-butanediol, 25g of dimer (1, 4-butanediol), 6.2g of glycerol and 4.2g of n-butyl titanate are put into a reaction kettle, and the temperature is raised to 220-240 ℃ and is kept constant for 120 min. Then, 1.25g of phosphorous acid was charged thereinto. Reducing the pressure in the reaction kettle to be below 50Pa within 30-60 minutes, and reacting for 60-120min at 220-260 ℃. Stopping stirring, filling high-purity nitrogen into the reaction kettle, extruding the resin out of the reaction kettle, and performing water-cooling granulation to obtain the polyester product. The performance results are shown in Table 2.

Example 8.3

Under the protection of high-purity nitrogen, putting 2.36kg of terephthalic acid, 2.36kg of adipic acid, 4.38kg of 1, 4-butanediol, 10g of dimer (1, 4-butanediol), 6.2g of glycerol and 4.2g of n-butyl titanate into a reaction kettle, heating to 220-240 ℃, and keeping the temperature constant for 120 min. Then, 1.25g of phosphorous acid was charged thereinto. Reducing the pressure in the reaction kettle to be below 50Pa within 30-60 minutes, and reacting for 60-120min at 220-260 ℃. Stopping stirring, filling high-purity nitrogen into the reaction kettle, extruding the resin out of the reaction kettle, and performing water-cooling granulation to obtain the polyester product. The performance results are shown in Table 2.

Example 8.4

Under the protection of high-purity nitrogen, 2.36kg of terephthalic acid, 2.36kg of adipic acid, 4.38kg of 1, 4-butanediol, 5g of dimer (1, 4-butanediol), 6.2g of glycerol and 4.2g of n-butyl titanate are put into a reaction kettle, and the temperature is raised to 220-240 ℃ and is kept constant for 120 min. Then, 1.25g of phosphorous acid was charged thereinto. Reducing the pressure in the reaction kettle to be below 50Pa within 30-60 minutes, and reacting for 60-120min at 220-260 ℃. Stopping stirring, filling high-purity nitrogen into the reaction kettle, extruding the resin out of the reaction kettle, and performing water-cooling granulation to obtain the polyester product. The performance results are shown in Table 2.

Example 8.5

Under the protection of high-purity nitrogen, 2.36kg of terephthalic acid, 2.36kg of adipic acid, 4.38kg of 1, 4-butanediol, 6.2g of glycerol and 4.2g of n-butyl titanate are put into a reaction kettle, and the temperature is increased to 220-240 ℃ and is kept constant for 120 min. Then, 1.25g of phosphorous acid was charged thereinto. Reducing the pressure in the reaction kettle to be below 50Pa within 30-60 minutes, and reacting for 60-120min at 220-260 ℃. Stopping stirring, filling high-purity nitrogen into the reaction kettle, extruding the resin out of the reaction kettle, and performing water-cooling granulation to obtain the polyester product. The performance results are shown in Table 2.

Example 8.6

Under the protection of high-purity nitrogen, putting 2.36kg of terephthalic acid, 2.36kg of adipic acid, 4.38kg of 1, 4-butanediol, 4.6g of poly (1, 4-butanediol) (Sigma-Aldrich, Mn-1000), 6.2g of glycerol and 4.2g of n-butyl titanate into a reaction kettle, heating to 220-240 ℃, and keeping the temperature for 120 min. Then, 1.25g of phosphorous acid was charged thereinto. Reducing the pressure in the reaction kettle to be below 50Pa within 30-60 minutes, and reacting for 60-120min at 220-260 ℃. Stopping stirring, filling high-purity nitrogen into the reaction kettle, extruding the resin out of the reaction kettle, and performing water-cooling granulation to obtain the polyester product. The performance results are shown in Table 2.

Example 8.7

Under the protection of high-purity nitrogen, putting 2.36kg of terephthalic acid, 2.36kg of adipic acid, 4.38kg of 1, 4-butanediol, 4.6g of poly (1, 4-butanediol) (Sigma-Aldrich, Mn-650), 6.2g of glycerol and 4.2g of n-butyl titanate into a reaction kettle, heating to 220-240 ℃, and keeping the temperature for 120 min. Then, 1.25g of phosphorous acid was charged thereinto. Reducing the pressure in the reaction kettle to be below 50Pa within 30-60 minutes, and reacting for 60-120min at 220-260 ℃. Stopping stirring, filling high-purity nitrogen into the reaction kettle, extruding the resin out of the reaction kettle, and performing water-cooling granulation to obtain the polyester product. The performance results are shown in Table 2.

TABLE 2

Example 8.6 addition of Poly (1, 4-butanediol) having a molecular weight of 1000 (repeating unit-CH)₂CH₂CH₂CH₂The number of-O-is about 14) to CH with an ether bonding oxygen atom₂Having a peak near the upper hydrogen atom¹H NMR is shown in FIG. 5. Since the peaks associated with the self-produced dimer (1, 4-butanediol) and the additional addition of poly (1, 4-butanediol) having a molecular weight of 1000 overlap in the vicinity of 3.4ppm in the polymerization product, only the repeating unit-CH in the polymerization product can be calculated₂CH₂CH₂CH₂-total O-content:

wherein the content of the first and second substances,

I₁and I_1'To be adjacent to terephthalic acidwith-CH groups bound to ether-bonded oxygen atoms in the repeating units of the poly (1, 4-butanediol)₂-integrated area of upper hydrogen atom peak;

I₂and I_2'is-CH linked to an ether linkage oxygen atom on a poly (1, 4-butanediol) repeat unit adjacent to adipic acid₂-integrated area of upper hydrogen atom peak;

I₃is-CH attached to an ether linkage oxygen atom in a poly (1, 4-butanediol) repeat unit not adjacent to terephthalic acid and adipic acid₂-integrated area of upper hydrogen atom peak;

I_Tis the integral area of 4 hydrogen atoms on a benzene ring of a terephthalic acid repeating unit;

I_A2-CH linking adipic acid repeat units to carbonyl groups₂-upper 4 hydrogen atoms integrated area;

however, the overlapping of the three peaks 2,2 'and 3 occurs, and the peak areas of 2 and 2' and the peak area of 3 in the overlapping peaks must be calculated independently to calculate X using the formula (2)_C。

In view of, I₁And I_1'Also can reflect the proportion of terephthalic acid repeating units, I₂And I_2'Also reflecting the ratio of adipic acid repeating units, we have the following relationship:

after simplifying equation (3), we obtain:

in addition, in the case of the optical fiber,

substituting equations (4) and (5) into equation (2) yields:

formula (6) is the repeat unit-CH in the polymerization product derived from all poly (1, 4-butanediol) (including self-generated and additionally added) based on the total molar amount of the first component A (diacid)₂CH₂CH₂CH₂-calculation of the molar content of O-.

As can be seen from examples 8.5-8.1 of Table 2, the resin color significantly worsened with increasing charge of dimer (1, 4-butanediol). At the same time, the addition of other poly (1, 4-butanediol) of higher molecular weight (examples 8.6 and 8.7) to the polymerization system had no significant effect on the color of the resin. This example 8 data further illustrates that dimerization (1, 4-butanediol) has an effect on the color of the resin, and that the color of the resin deteriorates with increasing levels of dimerization (1, 4-butanediol).