Semi-aromatic polyesters and their preparation methods and applications

Abstract

The present invention discloses a semi-aromatic polyester and its preparation method and application, which has a specific range of double bond content and has better melt heat residence stability and good color compared with known semi-aromatic polyesters.

Description

[Technical Field]

[0001] The present invention relates to the field of biodegradable polyesters, and more particularly to semi-aromatic polyesters having a specific double bond content and their preparation methods and applications. [Background technology]

[0002] Biodegradable aliphatic-aromatic copolyesters can be prepared from aliphatic diacids or their derivatives, aliphatic diols, and aromatic diacids or their derivatives. A typical example of this copolyester is Ecoflex, manufactured by BASF in Germany, which is made from 1,6-adipic acid (AA), 1,4-butanediol (BDO), and terephthalic acid. This copolyester has excellent processing properties due to its low melt volume flow rate (MVR), and good hydrolysis resistance due to its very low acid value. However, compared to aromatic polyesters such as PET and PBT, semi-aromatic polyesters are prone to thermal decomposition, resulting in the generation of structures such as double bonds and carboxyl groups after thermal degradation, which reduces the performance of the polymerization product and makes it unsuitable for subsequent use. Summary of the Invention

[0003] In order to solve the above problems, the present invention aims to provide a semi-aromatic polyester, which has a specific double bond content, and therefore has better melt heat retention stability and good color.

[0004] Another object of the present invention is to provide a method for preparing the semi-aromatic polyester.

[0005] The above object of the present invention is achieved by the following technical solutions.

[0006] A semi-aromatic polyester, Based on the total molar amount of the first component A, a1) 40 to 60 mol % of at least one aliphatic dicarboxylic acid or a derivative thereof; a2) a first component A containing 40 to 60 mol% of at least one aromatic dicarboxylic acid or a derivative thereof; A second component B is derived from a repeating unit consisting of a diol having 2 to 12 carbon atoms, The double bond content in the semi-aromatic polyester is 0.55 to 4.5 mmol / kg, preferably 0.70 to 2.5 mmol / kg, and more preferably 0.75 to 0.95 mmol / kg.

[0007] In the polyester synthesis process, the molecular structure of the final polyester varies greatly due to the influence of many factors, such as differences in the structure or ratio of raw material monomers, differences in the types of catalysts, branching agents and chain extenders, production process, reaction time, polymerization temperature, etc. In the present invention, research has found that the double bond content in semi-aromatic polyesters is closely related to the melt thermal retention stability and color of semi-aromatic polyesters.

[0008] In the present invention, it has been unexpectedly found through research that by controlling the double bond content in the semi-aromatic polyester within the range of 0.55 to 4.5 mmol / kg, the resulting semi-aromatic polyester has better melt heat retention stability and good color.

[0009] In the context of the present invention, component a1) an aliphatic dicarboxylic acid or derivative thereof is selected from one or more mixtures of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,11-undecanedicarboxylic acid, 1,10-decanedicarboxylic acid, undecanedioic acid, 1,12-dodecanedicarboxylic acid, hexadecanedioic acid, eicosanedioic acid or tetracosanedioic acid, or their ester derivatives or their anhydride derivatives.

[0010] Specific examples of component a1) include 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, 2,2,5,5-tetramethyladipic acid, pimelic acid, suberic acid, azelaic acid, dimethyl azelaate, sebacic acid, 1,11- It is selected from one or more of undecanedicarboxylic acid, 1,10-decanedicarboxylic acid, undecanedioic acid, 1,12-dodecanedicarboxylic acid, hexadecanedioic acid, eicosanedioic acid, tetracosanedioic acid, dimer acid, or an ester derivative thereof or an anhydride derivative thereof, preferably one or more of succinic acid, adipic acid, sebacic acid, 1,12-dodecanedicarboxylic acid, or an ester derivative thereof or anhydride derivative thereof, more preferably one or two of adipic acid, sebacic acid, or an ester derivative thereof or anhydride derivative thereof, and most preferably adipic acid, or an ester derivative thereof or an anhydride derivative thereof.

[0011] In the present invention, the aromatic dicarboxylic acid or its derivative, component a2), is selected from a mixture of one or more of terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, or their ester derivatives or their anhydride derivatives, and is preferably terephthalic acid, or its ester derivatives or its anhydride derivatives.

[0012] Specific examples of the component a2) include 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'-diphenyl ether dicarboxylic acid, dimethyl 3,4'-diphenyl ether dicarboxylate, 4,4'-diphenyl ether dicarboxylate, dimethyl 4,4'-diphenyl ether dicarboxylate, 3,4'-phenylene sulfide dicarboxylic acid, dimethyl 3,4'-phenylene sulfide dicarboxylate, 4,4 The carboxylic acid may be selected from one or more of 4,4'-diphenylsulfidedicarboxylic acid, dimethyl 4,4'-phenylenesulfidedicarboxylate, 3,4'-diphenylsulfonedicarboxylic acid, dimethyl 3,4'-diphenylsulfonedicarboxylate, 4,4'-diphenylsulfonedicarboxylic acid, dimethyl 4,4'-diphenylsulfonedicarboxylate, 3,4'-benzophenonedicarboxylic acid, dimethyl 3,4'-benzophenonedicarboxylate, 4,4'-benzophenonedicarboxylic acid, dimethyl 4,4'-benzophenonedicarboxylate, 1,4-naphthalenedicarboxylic acid, dimethyl 1,4-naphthalenedicarboxylate, 4,4'-methylenebis(benzoic acid), 4,4'-methylenebis(dimethylbenzoate), or an ester derivative or an anhydride derivative thereof, and preferably terephthalic acid or an ester derivative or an anhydride derivative thereof.

[0013] In the present invention, the second component B is selected from one or more of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol, and is preferably ethylene glycol, 1,3-propanediol or 1,4-butanediol.

[0014] Most preferably, when component a1) is adipic acid or its ester derivative or anhydride derivative, and component a2) is terephthalic acid or its ester derivative or anhydride derivative, the second component B is a combination of 1,4-butanediol.

[0015] Based on the total molar amount of the first component A, the semi-aromatic polyester according to the present invention also contains 0.01 to 5.0 mol % of a third component C and 0.01 to 5.0 mol % of a fourth component D.

[0016] The third component C is selected from one or more of tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerin, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid anhydride, 1,2,4,5-benzenetetracarboxylic acid, or pyromellitic dianhydride, and is preferably trimethylolpropane, pentaerythritol, or glycerin.

[0017] The fourth component, D, is a chain extender, which is a mixture of one or more of an isocyanate, an isocyanurate, a peroxide, an epoxide, an oxazoline, an oxazine, a lactam, a carbodiimide, or a polycarbodiimide containing two or more functional groups.

[0018] The isocyanate containing two or more functional groups may be an aromatic or aliphatic isocyanate, preferably an aromatic or 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.

[0019] More preferably, the aromatic diisocyanate is diphenylmethane 2,2'-diisocyanate, diphenylmethane 2,4'-diisocyanate, or diphenylmethane 4,4'-diisocyanate.

[0020] The isocyanate containing two or more functional groups may be tris(4-isocyanato-phenyl)methane, which has three rings.

[0021] Preferably, the aliphatic diisocyanate is any linear or branched alkylene diisocyanate or cycloalkylene diisocyanate containing 2 to 20 carbon atoms, more preferably 3 to 12 carbon atoms. The aliphatic diisocyanate may be hexamethylene 1,6-diisocyanate, isophorone diisocyanate, or methylenebis(4-isocyanatocyclohexane), most preferably hexamethylene 1,6-diisocyanate or isophorone diisocyanate.

[0022] Preferably, the isocyanurate having two 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. In particular, isocyanurates based on cyclic trimers, pentamers, or higher oligomers of n-hexamethylene diisocyanate, such as hexamethylene 1,6-diisocyanate, are preferred.

[0023] Preferably, the peroxide having two or more functional groups is preferably benzoyl peroxide, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-butylperoxy)methylcyclododecane, n-butyl 4,4-di(butylperoxy)pentanoate, dicumyl peroxide, tert-butyl peroxybenzoate, dibutyl peroxide, α,α-di(tert-butylperoxy)diisopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hex-3-yne, or tert-butylcumene peroxide.

[0024] Preferably, the epoxide having two or more functional groups is selected from the group consisting of hydroquinone diglycidyl ether, resorcinol diglycidyl ether, 1,6-hexanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, diglycidyl terephthalate, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, dimethyl diglycidyl phthalate, phenylene diglycidyl ether, ethylene diglycidyl ether, trimethylene diglycidyl ether, tetramethylene diglycidyl ether, hexamethylene diglycidyl ether, sorbitol diglycidyl ether, polyglycerin polyglycidyl ether, and the like. diglycidyl ether, pentaerythritol polyglycidyl ether, diglycerin polyglycidyl ether, glycerin polyglycidyl ether, trimethylolpropane polyglycidyl ether, 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 poly 1,4-butylene glycol diglycidyl ether.

[0025] The epoxide having two or more functional groups is preferably a copolymer based on styrene, acrylic esters and / or methacrylic esters and containing epoxy groups, the epoxy groups being preferably glycidyl methacrylate. Compounds that 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 even more preferably greater than 50% by weight. The epoxy equivalent weight in these polymers is preferably 150 to 3000 g / equivalent, more preferably 200 to 500 g / equivalent. The weight-average molecular weight Mw of the polymer is preferably 2000 to 25000, more preferably 3000 to 8000. The number-average molecular weight Mn of the polymer is preferably 400 to 6000, more preferably 1000 to 4000. The polydispersity index (Q=Mw / Mn) is preferably 1.5 to 5.

[0026] The oxazoline and oxazine having two or more functional groups are preferably dioxazoline or dioxazine, the bridging moiety of which is a single bond, (CH2)z-alkylene (where z=2, 3, or 4), such as methylene, eth-1,2-diyl, propa-1,3-diyl, or propa-1,2-diyl, or phenylene. Specifically, the dioxazoline includes 2,2'-bis(2-oxazoline), bis(2-oxazolinyl)methane, 1,2-bis(2-oxazolinyl)ethane, 1,3-bis(2-oxazolinyl)propane, 1,4-bis(2-oxazolinyl)butane, 2,2'-bis(2-oxazoline), 2,2'-bis(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 -phenylmethyl-2-oxazoline), 2,2'-p-phenylenebis(4-methyl-2-oxazoline), 2,2'-p-phenylenebis(4,4'-dimethyl-2-oxazoline), 2,2'-m-phenylenebis(4-methyl-2-oxazoline), 2,2'-m-phenylenebis(4,4'-dimethyl-2-oxazoline), 2,2'-hexamethylenebis(2-oxazoline), 2,2'-octamethyl 2,2'-tetramethylenebis(4,4'-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethanebis(2-oxazoline), 2,2'-cyclohexylenebis(2-oxazoline), or 2,2'-diphenylene(2-oxazoline).

[0027] More preferred is 1,4-bis(2-oxazolinyl)benzene, 1,2-bis(2-oxazolinyl)benzene, or 1,3-bis(2-oxazolinyl)benzene.

[0028] 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.

[0029] The carbodiimide or polycarbodiimide having two or more functional groups is preferably N,N'-di-2,6-diisopropylphenylcarbodiimide, N,N'-di-o-tolylcarbodiimide, N,N'-diphenylcarbodiimide, N,N'-dioctyldecylcarbodiimide, N,N'-di-2,6-dimethylphenylcarbodiimide, N-tolyl-N'-cyclohexylcarbodiimide, N,N'-di-2,6-di-tert-butylphenylcarbodiimide, N-tolyl-N'-phenylcarbodiimide, N, N'-di-p-nitrophenylcarbodiimide, N,N'-di-p-aminophenylcarbodiimide, N,N'-di-p-hydroxyphenylcarbodiimide, N,N'-dicyclohexylcarbodiimide, N,N'-di-p-tolylcarbodiimide, p-phenylenebisdi-o-tolylcarbodiimide, p-phenylenebisdicyclohexylcarbodiimide, hexamethylenebisdicyclohexylcarbodiimide, 4,4'-dicyclohexylmethanecarbodiimide, ethylenebisdiphenylcarbodiimide, N,N'- Benzyl carbodiimide, N-octadecyl-N'-phenylcarbodiimide, N-benzyl-N'-phenylcarbodiimide, N-octadecyl-N'-tolylcarbodiimide, N-cyclohexyl-N'-tolylcarbodiimide, N-phenyl-N'-tolylcarbodiimide, N-benzyl-N'-tolylcarbodiimide, N,N'-di-o-ethylphenylcarbodiimide, N,N'-di-p-ethylphenylcarbodiimide, N,N'-di-o-isopropylphenylcarbodiimide, N,N'-di-p-isopropyl N,N'-di-o-isobutylphenylcarbodiimide, N,N'-di-p-isobutylphenylcarbodiimide, N,N'-di-2,6-diethylphenylcarbodiimide, N,N'-di-2-ethyl-6-isopropylphenylcarbodiimide, N,N'-di-2-isobutyl-6-isopropylphenylcarbodiimide, N,N'-di-2,4,6-trimethylphenylcarbodiimide, N,N'-di-2,4,6-triisopropylphenylcarbodiimide, N,N'-di-2,4,6-triisobutylphenylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, di-β-naphthylcarbodiimide or di-tert-butylcarbodiimide.

[0030] Preferably, the viscosity number of the semi-aromatic polyester is 150-350 ml / g, measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0031] Preferably, the carboxyl group content of the semi-aromatic polyester is 5 to 60 mmol / kg, more preferably 10 to 30 mmol / kg.

[0032] The present invention also provides a method for preparing the above semi-aromatic polyester, which comprises the steps of: a step S1 of adding a1 in the first component A and the second component B to a slurry blending kettle in accordance with the ratio, transporting the blended slurry to a first esterification reactor, adding the refluxed second component B and the catalyst to the first esterification reactor through a separate route, and conducting an esterification reaction at 150 to 200°C and 30 to 110 kPa for 2 to 4 hours to obtain an esterification product Ba1; and adding a2 in the first component A and the second component B to a slurry blending kettle in accordance with the ratio, transporting the blended slurry to a second esterification reactor, adding the refluxed second component B and the catalyst to the second esterification reactor through a separate route, and conducting an esterification reaction at 200 to 250°C and 30 to 110 kPa for 2 to 4 hours to obtain an esterification product Ba2; Step S2, in which the esterification product Ba1 of step S1 is subjected to a primary polycondensation reaction at a reaction temperature of 170-220°C and a pressure of 1-10 kPa, and the esterification product Ba2 of step S1 is subjected to a primary polycondensation reaction at a reaction temperature of 230-270°C and a pressure of 1-10 kPa, and the two reaction products are subjected to a primary polycondensation reaction independently until each reaction product reaches a viscosity number of 15-60 ml / g as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to the GB / T 17931-1999 standard, thereby obtaining primary polycondensation products Pre-Ba1 and Pre-Ba2, respectively; Step S3: transferring the primary polycondensation reaction product Pre-Ba1 obtained in step S2 to a first final polymerization vessel at a reaction temperature of 180-230°C and a pressure of 10-500 Pa, and transferring the primary polycondensation reaction product Pre-Ba2 obtained in step S2 to a second final polymerization vessel at a reaction temperature of 220-270°C and a pressure of 10-500 Pa, and independently polycondensing the two reaction products until the reaction products reach a viscosity of 50-180 ml / g as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard, thereby obtaining final polymerization products Poly-Ba1 and Poly-Ba2, respectively; and step S4, in which the final polymerization products Poly-Ba1 and Poly-Ba2 obtained in step S3 are mixed and reacted in a mixer to obtain a semi-aromatic polyester having a viscosity of 150 to 300 ml / g as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0033] Preferably, in step S1, a catalyst is added in an amount of 0.001 to 1% by weight of the final semi-aromatic polyester when preparing the Ba2 esterification product. Preferably, the catalyst addition amount is 0.02 to 0.2% by weight of the final semi-aromatic polyester. Controlling the catalyst addition amount can improve the stability of subsequent processing. Furthermore, the catalyst may be a tin compound, antimony compound, cobalt compound, lead compound, zinc compound, aluminum compound, or titanium compound, more preferably a zinc compound, aluminum compound, or titanium compound, and most preferably a titanium compound. The advantage of titanium compounds, such as tetrabutyl orthotitanate or tetraisopropyl orthotitanate, over other compounds is that the residual toxicity remaining in the product or downstream products is low. This characteristic is particularly important for biodegradable polyesters, as they enter the environment directly in the form of compost bags or coated films.

[0034] All pressures mentioned in the process of this invention are absolute pressures (absolute pressure).

[0035] In S1, the total molar amount of the second component B is usually 1.1 to 3.0 times that of the first component A, and excess second component B is recovered through a purification device (usually a distillation column) connected to the esterification reactor and then fed to the esterification reactor. The amount of recovered second component B is usually 20 to 50% by weight of the amount of fresh second component B.

[0036] In S2, when preparing the Pre-Ba1 prepolymer, the reaction temperature is more preferably 180 to 200° C., and the reaction pressure is more preferably 2 to 5 kPa.

[0037] In step S2, when preparing the Pre-Ba2 prepolymer, the remaining catalyst from step S1 can be added in step S2, if necessary. The reaction temperature is more preferably 240 to 260°C, and the reaction pressure is more preferably 2 to 5 kPa.

[0038] The typical reaction time for preparing Pre-Ba1 and Pre-Ba2 in S2 is 2-5 hours. Under normal circumstances, this reaction time results in primary polycondensation products Pre-Ba1 and Pre-Ba2 with viscosities of 15-60 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999. The carboxyl group content of the primary polycondensation products Pre-Ba1 and Pre-Ba2 after the S2 reaction is typically 10-60 mmol / kg.

[0039] In the polycondensation reaction step S3, a passivator can be mixed with the prepolyester, if necessary. Usable passivators are typically phosphorus compounds, including phosphoric acid, phosphorous acid, and their esters. The amount of passivator is typically 0.001 to 0.1% by weight, preferably 0.01 to 0.05% by weight, based on the weight of the final polyester.

[0040] In S3, when preparing Poly-Ba1 polyester, the reaction temperature is more preferably 190 to 220°C, and the reaction pressure is more preferably 50 to 200Pa.

[0041] In S3, when preparing Poly-Ba2 polyester, the reaction temperature is more preferably 240 to 260°C, and the reaction pressure is more preferably 20 to 100Pa.

[0042] In S3, the polycondensation reaction time is preferably 1 to 5 hours, more preferably 2 to 4 hours. The resulting Poly-Ba1 and Poly-Ba2 polyesters have a viscosity of 50 to 180 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C, according to GB / T 17931-1999. Furthermore, the carboxyl group content of the Poly-Ba1 and Poly-Ba2 polyesters after the S3 reaction is typically 5 to 60 mmol / kg, more preferably 10 to 30 mmol / kg.

[0043] In step S4, Poly-Ba1 and Poly-Ba2 are mixed in a mixer, which includes a feed system, a temperature control system, a high-shear homogenizing pump, and a homogenizer. The mixer temperature range is 200°C to 280°C, preferably 240°C to 260°C, and the residence time of Poly-Ba1 and Poly-Ba2 in the mixer is 1 to 4 hours, preferably 1.5 to 2 hours. After passing through the mixer, the resulting reaction product reaches a viscosity of 150 to 300 ml / g, measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0044] Preferably, the preparation method optionally further includes step S5, in which the semi-aromatic polyester obtained in step S4 is added to a fourth component D to carry out a chain extension reaction at a reaction temperature of 200 to 270°C, with a reaction residence time of 0.5 to 15 minutes, preferably 2 to 5 minutes. The reaction is completed when the reaction product reaches a viscosity number of 150 to 350 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0045] In the process of the present invention, aliphatic diacids and aromatic diacids are polymerized independently before the chain extension step, and then the aliphatic polyester oligomer and aromatic polyester oligomer are mixed in the chain extension step. The resulting semi-aromatic polyester has a double bond content of 0.55-4.5 mmol / kg, and therefore has good melt thermal retention stability and good color.

[0046] The above-mentioned semi-aromatic polyester of the present invention can also be prepared via other processes, such as directly copolymerizing a double bond-containing compound (e.g., undecylenic acid) during the synthesis process to control the double bond content of the semi-aromatic polyester to 0.55 to 4.5 mmol / kg.

[0047] The present invention also provides the application of the above semi-aromatic polyester in the manufacture of compostable and degradable products, which can be fibers, films or containers, etc.

[0048] The present invention also provides a semi-aromatic polyester molding composition, which comprises, in weight percentages: 5 to 95% by weight of the semi-aromatic polyester; 5 to 95 wt. % of additives and / or other polymers; and 0 to 70% by weight of reinforcing materials and / or fillers.

[0049] As a particular option, the additive and / or other polymer may be at least one or more components selected from aliphatic polyesters, polycaprolactone, starch, cellulose, polyhydroxyalkanoates, and polylactic acid.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] The present invention provides a semi-aromatic polyester, which has a specific double bond content and has better melt heat residence stability and good color compared to known semi-aromatic polyesters. [Brief explanation of the drawings]

[0052]

Figure 1

Figure 2

[0053] Unless otherwise specified, the raw materials, reagents, and solvents used in the present invention were purchased commercially without any treatment. The present invention will be described in more detail below in conjunction with examples. However, the embodiments of the present invention are not limited to the following examples. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered equivalent substitutions and are all included within the scope of protection of the present invention. In this specification, "parts" and "%" mean "parts by mass" and "% by mass," respectively, unless otherwise specified.

[0054] Performance test method: Test method for double bond content in semi-aromatic polyester (taking PBAT obtained by the reaction of terephthalic acid, adipic acid and 1,4-butanediol in Example 1 as an example): A 20 mg sample of semi-aromatic polyester was dissolved in 0.6 ml of deuterated chloroform and analyzed using a Bruker AV 500 nuclear magnetic resonance spectrometer. 1 H NMR was measured, and the peak of the chloroform solvent was standardized at 7.26 ppm. Referring to the literature (J. Appl. Polym. Sci. 2007, 104(4):2643-2649.), it can be seen that the four hydrogen atoms of the benzene ring in the terephthalic acid repeat unit appear at around 8.10 ppm, and the four hydrogen atoms of the two CH2 units adjacent to the carbonyl group in the adipic acid repeat unit appear at around 2.33 ppm. This is shown in Figure 1. The molar content of the diacid component was determined by the integrated area (I) of the two peaks at 8.10 ppm and 2.33 ppm. T and I A ) can be expressed as Molar content of terephthalic acid in PBAT = I T I(I T +I A )×100% Adipic acid molar content in PBAT = I A I(I T +I A )×100%

[0055] 3-Buten-1-ol (CAS: 627-27-0) in the literature and SDBS database 1 The HNMR spectrum shows that Peak 1 at 5.0-5.2 ppm is the peak of two hydrogen atoms CH2=CH- on the terminal methylene group of the double bond, and Peak 2 at 5.7-5.9 ppm is the peak of hydrogen atoms CH2=CH- on the methine group of the double bond, as shown in Figure 2.

[0056] Since the double bond content of semi-aromatic polyesters is low, the double bond content C (unit: mmol / kg) can be calculated based on the peaks of the two hydrogen atoms on the terminal methylene groups of the double bonds as follows:

number

[0057] Viscosity number of semi-aromatic polyester: According to the GB / T 17931-1999 standard, the sample concentration was 5 mg / ml measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C.

[0058] Carboxyl group content: First, the acid number AN (mg KOH / g) was determined according to DIN EN 12634 of October 1998, and then the carboxyl group content (mmol / kg) = AN / 56 x 10 3 The solvent mixture used contained 1 part DMSO, 8 parts isopropyl alcohol, and 7 parts toluene by volume. The semi-aromatic polyester sample was heated to 70°C to dissolve all polymers and form a clear solution. The solution temperature was maintained between 60 and 70°C to avoid polymer precipitation during the titration process. To avoid the use of highly toxic tetramethylammonium hydroxide, tetrabutylammonium hydroxide was used as the titrant. To prevent the mixed solvent from absorbing CO2 from the air and affecting the amount of titrant consumed by the blank solvent, the blank solvent was heated to 70°C and then held at a constant temperature for 0.5 hours. To prevent further CO2 absorption by the blank solvent after heating, the blank solvent was immediately titrated with alkaline solution.

[0059] Melt heat retention stability test: The melt index (MFR) of a semi-aromatic polyester was measured according to GB / T 3682.1-2018 Plastics: Part 1: Standard Method for Determination of Melt Mass-Flow Rate and Melt Volume-Flow Rate in Thermoplastics. The test temperature was 190°C and the load was 2.16 kg. The melt index was obtained after 5 minutes of melting and recorded as MFR0. The melt index was obtained after 20 minutes of melting and recorded as MFR1. The heat retention melt index retention (R) was calculated as MFR0 / MFR1 x 100%. The lower the R value, the worse the heat retention stability.

[0060] Semi-aromatic polyester colors: The pelletized and dried samples were taken and tested according to GB / T 14190-2017 5.5.2, Method B (dry method). The L, a, b values ​​of the Hunter Lab color system were obtained to define the Hunter whiteness. WH=100-[(100-L) 2 +a 2 +b 2 ] 1 / 2 The higher the Hunter whiteness value, the better the color of the sample.

[0061] Example 1: S1. 437 kg / h of adipic acid and 404 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a first esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 135 kg / h, and simultaneously 0.60 kg / h of glycerin and 0.224 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 190°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, yielding an esterification product Ba1.

[0062] 437 kg / h of terephthalic acid and 356 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a second esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 119 kg / h, and simultaneously 0.53 kg / h of glycerin and 0.406 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, and an esterification product Ba2 was obtained.

[0063] S2. The esterification product Ba1 was transferred to the first preliminary polycondensation reactor, and simultaneously 0.096 kg / h of n-butyl titanate and 0.245 kg / h of triphenyl phosphate were added. The temperature was 200°C, the reactor pressure was 4 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba1 reached a viscosity of 44 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0064] The esterification product Ba2 was transferred to a second pre-polycondensation reactor, and simultaneously 0.174 kg / h of n-butyl titanate and 0.44 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba2 reached a viscosity of 27 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0065] S3. The prepolymer Pre-Ba1 was fed to the first final polymerization vessel through a melt pump, and the temperature of the first final polymerization vessel was set to 220°C, the pressure to 120 Pa, and the reaction time to 2 to 4 hours. At this point, the reaction product Poly -Ba1 reached a viscosity number of 138 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0066] The prepolymer Pre-Ba2 was fed to the second final polymerization reactor through a melt pump, and the temperature of the second final polymerization reactor was set to 250°C, the pressure to 20 Pa, and the reaction time to 2 to 4 hours. Poly -Ba2 reached a viscosity number of 115 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0067] S4. The two final polymerization products, Poly-Ba1 and Poly-Ba2, were continuously fed into a mixer, the temperature of which was 250°C, and the residence time was 1.5 hours. The resulting polyester was then introduced into a twin-screw extruder, and simultaneously 5.2 kg / h of hexamethylene diisocyanate (HDI) was metered in, and the temperature was set to 240°C. After a residence time of 3 minutes, the polyester was pelletized using an underwater pelletizer and then dried to obtain the final polyester product.

[0068] Example 2: S1. 605 kg / h of sebacic acid and 404 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a first esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 135 kg / h, and simultaneously 0.60 kg / h of glycerin and 0.224 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 180°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, yielding an esterification product Ba1.

[0069] 437 kg / h of terephthalic acid and 356 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a second esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 119 kg / h, and simultaneously 0.53 kg / h of glycerin and 0.406 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, and an esterification product Ba2 was obtained.

[0070] S2. The esterification product Ba1 was transferred to the first preliminary polycondensation reactor, and simultaneously 0.096 kg / h of n-butyl titanate and 0.245 kg / h of triphenyl phosphate were added. The temperature was 190°C, the reactor pressure was 4 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba1 reached a viscosity of 46 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0071] The esterification product Ba2 was transferred to a second pre-polycondensation reactor, and simultaneously 0.174 kg / h of n-butyl titanate and 0.44 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba2 reached a viscosity of 29 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0072] S3. The prepolymer Pre-Ba1 was fed to the first final polymerization reactor through a melt pump, and the temperature of the first final polymerization reactor was set to 210°C, the pressure to 120 Pa, and the reaction time to 2 to 4 hours. At this point, the reaction product Poly -Ba1 reached a viscosity number of 147 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0073] The prepolymer Pre-Ba2 was fed to the second final polymerization reactor through a melt pump, and the temperature of the second final polymerization reactor was set to 250°C, the pressure to 20 Pa, and the reaction time to 2 to 4 hours. Poly -Ba2 reached a viscosity number of 119 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0074] S4. The two final polymerization products, Poly-Ba1 and Poly-Ba2, were continuously fed into a mixer, the temperature of which was 250°C, and the residence time was 1.4 hours. The resulting polyester was then introduced into a twin-screw extruder, and simultaneously 5.2 kg / h of hexamethylene diisocyanate (HDI) was metered in, and the temperature was set to 240°C. After a residence time of 3 minutes, the polyester was pelletized using an underwater pelletizer and then dried to obtain the final polyester product.

[0075] Example 3: S1. 437 kg / h of adipic acid and 404 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a first esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 135 kg / h, and simultaneously 0.88 kg / h of trimethylolpropane (TMP) and 0.224 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 190°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, yielding an esterification product Ba1.

[0076] 437 kg / h of terephthalic acid and 356 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a second esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 119 kg / h, and simultaneously 0.772 kg / h of trimethylolpropane and 0.406 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, and an esterification product Ba2 was obtained.

[0077] S2. The esterification product Ba1 was transferred to the first preliminary polycondensation reactor, and simultaneously 0.096 kg / h of n-butyl titanate and 0.245 kg / h of triphenyl phosphate were added. The temperature was 200°C, the reactor pressure was 4 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba1 reached a viscosity of 42 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0078] The esterification product Ba2 was transferred to a second pre-polycondensation reactor, and simultaneously 0.174 kg / h of n-butyl titanate and 0.44 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba2 reached a viscosity of 25 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0079] S3. The prepolymer Pre-Ba1 was fed to the first final polymerization vessel through a melt pump, and the temperature of the first final polymerization vessel was set to 220°C, the pressure to 120 Pa, and the reaction time to 2 to 4 hours. At this point, the reaction product Poly -Ba1 reached a viscosity number of 129 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0080] The prepolymer Pre-Ba2 was fed to the second final polymerization vessel through a melt pump, and the temperature of the second final polymerization vessel was set to 250°C, the pressure to 20 Pa, and the reaction time to 2 to 4 hours. Poly -Ba2 reached a viscosity number of 111 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0081] S4. The two final polymerization products, Poly-Ba1 and Poly-Ba2, were continuously fed into a mixer, the temperature of which was 250°C, and the residence time was 1.5 hours. The resulting polyester was then introduced into a twin-screw extruder, and simultaneously 5.2 kg / h of hexamethylene diisocyanate (HDI) was metered in, and the temperature was set to 240°C. After a residence time of 3 minutes, the polyester was pelletized using an underwater pelletizer and then dried to obtain the final polyester product.

[0082] Example 4: S1. 437 kg / h of adipic acid and 404 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a first esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 135 kg / h, and simultaneously 0.224 kg / h of n-butyl titanate was added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 190°C, and the residence time to 2 to 4 hours. The water, tetrahydrofuran, and butanediol produced by the reaction were removed, and an esterification product Ba1 was obtained.

[0083] 437 kg / h of terephthalic acid and 356 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a second esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 119 kg / h, and simultaneously 0.406 kg / h of n-butyl titanate was added. The pressure of the reactor was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, and an esterification product Ba2 was obtained.

[0084] S2. The esterification product Ba1 was transferred to the first preliminary polycondensation reactor, and simultaneously 0.096 kg / h of n-butyl titanate and 0.245 kg / h of triphenyl phosphate were added. The temperature was 200°C, the reactor pressure was 4 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba1 reached a viscosity of 49 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0085] The esterification product Ba2 was transferred to a second pre-polycondensation reactor, and simultaneously 0.174 kg / h of n-butyl titanate and 0.44 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba2 reached a viscosity of 35 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0086] S3. The prepolymer Pre-Ba1 was fed to the first final polymerization vessel through a melt pump, and the temperature of the first final polymerization vessel was set to 220°C, the pressure to 120 Pa, and the reaction time to 2 to 4 hours. At this point, the reaction product Poly -Ba1 reached a viscosity number of 141 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0087] The prepolymer Pre-Ba2 was fed to the second final polymerization vessel through a melt pump, and the temperature of the second final polymerization vessel was set to 250°C, the pressure to 20 Pa, and the reaction time to 2 to 4 hours. Poly -Ba2 reached a viscosity number of 120 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0088] S4. The two final polymerization products, Poly-Ba1 and Poly-Ba2, were continuously fed into a mixer, the temperature of which was 250°C, and the residence time was 1.5 hours. The resulting polyester was then introduced into a twin-screw extruder, and simultaneously 5.2 kg / h of hexamethylene diisocyanate (HDI) was metered in, and the temperature was set to 240°C. After a residence time of 3 minutes, the polyester was pelletized using an underwater pelletizer and then dried to obtain the final polyester product.

[0089] Example 5: S1. 437 kg / h of adipic acid and 404 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a first esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 135 kg / h, and simultaneously 0.60 kg / h of glycerin and 0.224 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 190°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, yielding an esterification product Ba1.

[0090] 437 kg / h of terephthalic acid and 356 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a second esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 119 kg / h, and simultaneously 0.53 kg / h of glycerin and 0.406 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, and an esterification product Ba2 was obtained.

[0091] S2. The esterification product Ba1 was transferred to the first preliminary polycondensation reactor, and simultaneously 0.096 kg / h of n-butyl titanate and 0.245 kg / h of triphenyl phosphate were added. The temperature was 200°C, the reactor pressure was 4 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba1 reached a viscosity of 42 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0092] The esterification product Ba2 was transferred to a second pre-polycondensation reactor, and simultaneously 0.174 kg / h of n-butyl titanate and 0.44 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba2 reached a viscosity of 28 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0093] S3. The prepolymer Pre-Ba1 was fed to the first final polymerization vessel through a melt pump, and the temperature of the first final polymerization vessel was set to 220°C, the pressure to 120 Pa, and the reaction time to 2 to 4 hours. At this point, the reaction product Poly -Ba1 reached a viscosity number of 140 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0094] The prepolymer Pre-Ba2 was fed to the second final polymerization vessel through a melt pump, and the temperature of the second final polymerization vessel was set to 250°C, the pressure to 20 Pa, and the reaction time to 2 to 4 hours. Poly -Ba2 reached a viscosity number of 125 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0095] S4. The two final polymerization products, Poly-Ba1 and Poly-Ba2, were continuously fed into a mixer at a temperature of 250°C and a residence time of 1.5 hours. The resulting polyester was then introduced into a twin-screw extruder, and simultaneously 11.2 kg / h of N,N'-bis(2,6-diisopropylphenyl)carbodiimide (Stabaxol I) was metered in, and the temperature was set to 240°C. After a residence time of 3 minutes, the polyester was pelletized using an underwater pelletizer and then dried to obtain the final polyester product.

[0096] Example 6: S1. 437 kg / h of adipic acid and 404 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a first esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 135 kg / h, and simultaneously 0.60 kg / h of glycerin and 0.224 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 190°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, yielding an esterification product Ba1.

[0097] 600 kg / h of terephthalic acid and 488 kg / h of 1,4-butanediol were continuously added to a slurry preparation kettle, and the prepared slurry was continuously supplied to a second esterification reactor. The flow rate of 1,4-butanediol from the bottom of the process tower via a separate route was set to 163 kg / h. Simultaneously, 0.73 kg / h of glycerin and 0.56 kg / h of n-butyl titanate were added, and the reactor pressure was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, and the resulting esterification product A1 was continuously extracted from the reactor to obtain an esterification product Ba2.

[0098] S2. The esterification product Ba1 was transferred to the first preliminary polycondensation reactor, and simultaneously 0.096 kg / h of n-butyl titanate and 0.245 kg / h of triphenyl phosphate were added. The temperature was 200°C, the reactor pressure was 4 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba1 reached a viscosity of 47 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0099] The esterification product Ba2 was transferred to a second pre-polycondensation reactor, and simultaneously 0.24 kg / h of n-butyl titanate and 0.60 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba2 reached a viscosity of 35 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0100] S3. The prepolymer Pre-Ba1 was fed to the first final polymerization vessel through a melt pump, and the temperature of the first final polymerization vessel was set to 220°C, the pressure to 120 Pa, and the reaction time to 2 to 4 hours. At this point, the reaction product Poly -Ba1 reached a viscosity number of 132 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0101] The prepolymer Pre-Ba2 was fed to the second final polymerization vessel through a melt pump, and the temperature of the second final polymerization vessel was set to 250°C, the pressure to 20 Pa, and the reaction time to 2 to 4 hours. Poly -Ba2 reached a viscosity number of 119 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0102] S4. The two final polymerization products, Poly-Ba1 and Poly-Ba2, were continuously fed into a mixer, the temperature of which was 250°C, and the residence time was 1.5 hours. The resulting polyester was then introduced into a twin-screw extruder, and simultaneously 6.11 kg / h of hexamethylene diisocyanate (HDI) was metered in, and the temperature was set to 240°C. After a residence time of 3 minutes, the polyester was pelletized using an underwater pelletizer and then dried to obtain the final polyester product.

[0103] Example 7: S1. 437 kg / h of adipic acid and 404 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a first esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 135 kg / h, and simultaneously 0.60 kg / h of glycerin and 0.224 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 190°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, yielding an esterification product Ba1.

[0104] 437 kg / h of terephthalic acid and 356 kg / h of 1,4-butanediol were continuously added to a slurry preparation kettle, and the prepared slurry was continuously supplied to a second esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 119 kg / h. Simultaneously, 0.53 kg / h of glycerin and 0.406 kg / h of n-butyl titanate were added, and the reactor pressure was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, and the resulting esterification product A1 was continuously extracted from the reactor to obtain an esterification product Ba2.

[0105] S2. The esterification product Ba1 was transferred to the first pre-polycondensation reactor, and simultaneously 0.096 kg / h of n-butyl titanate and 0.245 kg / h of triphenyl phosphate were added. The temperature was 200°C, the reactor pressure was 4 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba1 reached a viscosity of 40 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0106] The esterification product Ba2 was transferred to a second pre-polycondensation reactor, and simultaneously 0.174 kg / h of n-butyl titanate and 0.44 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba2 reached a viscosity of 29 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0107] S3. The prepolymer Pre-Ba1 was fed to the first final polymerization vessel through a melt pump, and the temperature of the first final polymerization vessel was set to 220°C, the pressure to 120 Pa, and the reaction time to 2 to 4 hours. At this point, the reaction product Poly -Ba1 reached a viscosity number of 130 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0108] The prepolymer Pre-Ba2 was fed to the second final polymerization vessel through a melt pump, and the temperature of the second final polymerization vessel was set to 250°C, the pressure to 20 Pa, and the reaction time to 2 to 4 hours. Poly -Ba2 reached a viscosity number of 114 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0109] S4. The two final polymerization products, Poly-Ba1 and Poly-Ba2, were continuously fed into a mixer, the temperature of which was 250°C, and the residence time was 1.5 hours. The resulting polyester was then introduced into a twin-screw extruder, and simultaneously 5.2 kg / h of hexamethylene diisocyanate (HDI) was metered in, and the temperature was set to 240°C. After a residence time of 6 minutes, the polyester was pelletized using an underwater pelletizer and then dried to obtain the final polyester product.

[0110] Example 8: S1. 437 kg / h of adipic acid and 404 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a first esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 135 kg / h, and simultaneously 0.60 kg / h of glycerin and 0.224 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 190°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, yielding an esterification product Ba1.

[0111] 437 kg / h of terephthalic acid and 356 kg / h of 1,4-butanediol were continuously added to a slurry preparation kettle, and the prepared slurry was continuously supplied to a second esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 119 kg / h. Simultaneously, 0.53 kg / h of glycerin and 0.406 kg / h of n-butyl titanate were added, and the reactor pressure was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, and the resulting esterification product A1 was continuously extracted from the reactor to obtain an esterification product Ba2.

[0112] S2. The esterification product Ba1 was transferred to the first preliminary polycondensation reactor, and simultaneously 0.096 kg / h of n-butyl titanate and 0.245 kg / h of triphenyl phosphate were added. The temperature was 200°C, the reactor pressure was 4 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba1 reached a viscosity of 43 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0113] The esterification product Ba2 was transferred to a second pre-polycondensation reactor, and simultaneously 0.174 kg / h of n-butyl titanate and 0.44 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba2 reached a viscosity of 25 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0114] S3. The prepolymer Pre-Ba1 was fed to the first final polymerization vessel through a melt pump, and the temperature of the first final polymerization vessel was set to 220°C, the pressure to 120 Pa, and the reaction time to 2 to 4 hours. At this point, the reaction product Poly -Ba1 reached a viscosity number of 133 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0115] The prepolymer Pre-Ba2 was fed to the second final polymerization vessel through a melt pump, and the temperature of the second final polymerization vessel was set to 250°C, the pressure to 20 Pa, and the reaction time to 2 to 4 hours. Poly -Ba2 reached a viscosity number of 112 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0116] S4. The two final polymerization products Poly-Ba1 and Poly-Ba2 were continuously fed into a mixer, the mixer temperature was 250°C, and the residence time was 1.5 hours. The resulting polyester was then introduced into a twin-screw extruder, and simultaneously 5.2 kg / h of hexamethylene diisocyanate (HDI) was metered in, and the temperature was set to 240°C. After a residence time of 12 minutes, the polyester was pelletized using an underwater pelletizer and then dried to obtain the final polyester product.

[0117] Example 9: S1. 437 kg / h of adipic acid and 404 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a first esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 135 kg / h, and simultaneously 0.60 kg / h of glycerin and 0.224 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 190°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, yielding an esterification product Ba1.

[0118] 437 kg / h of terephthalic acid and 356 kg / h of 1,4-butanediol were continuously added to a slurry preparation kettle, and the prepared slurry was continuously supplied to a second esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 119 kg / h. Simultaneously, 0.53 kg / h of glycerin and 0.406 kg / h of n-butyl titanate were added, and the reactor pressure was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, and the resulting esterification product A1 was continuously extracted from the reactor to obtain an esterification product Ba2.

[0119] S2. The esterification product Ba1 was transferred to the first preliminary polycondensation reactor, and simultaneously 0.096 kg / h of n-butyl titanate and 0.245 kg / h of triphenyl phosphate were added. The temperature was 200°C, the reactor pressure was 4 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba1 reached a viscosity of 47 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0120] The esterification product Ba2 was transferred to a second pre-polycondensation reactor, and simultaneously 0.174 kg / h of n-butyl titanate and 0.44 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-Ba2 reached a viscosity of 29 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0121] S3. The prepolymer Pre-Ba1 was fed to the first final polymerization vessel through a melt pump, and the temperature of the first final polymerization vessel was set to 220°C, the pressure to 120 Pa, and the reaction time to 2 to 4 hours. At this point, the reaction product Poly -Ba1 reached a viscosity number of 136 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0122] The prepolymer Pre-Ba2 was fed to the second final polymerization vessel through a melt pump, and the temperature of the second final polymerization vessel was set to 250°C, the pressure to 20 Pa, and the reaction time to 2 to 4 hours. Poly -Ba2 reached a viscosity number of 120 ml / g measured in a phenol / o-dichlorobenzene solution with a weight ratio of 1:1 according to GB / T 17931-1999 standard in a constant temperature water bath at 25±0.05°C.

[0123] S4. The two final polymerization products, Poly-Ba1 and Poly-Ba2, were continuously fed into a mixer at a temperature of 250°C and a residence time of 2 hours. The polyesters were then pelletized using an underwater pelletizer and then dried to obtain the final polyester products.

[0124] Example 10: Under the protection of high-purity nitrogen, 1951 g of terephthaloyl chloride, 2000 g of adipoyl chloride, and 0.73 g of undecenoyl chloride (CAS: 38460-95-6) were dissolved in 2000 ml of dichloromethane to obtain an acyl chloride solution, which was then stored in an ice bath and cooled to 0 °C for later use. 1890 g of 1,4-butanediol and 4240 g of triethylamine were added to 3000 ml of dichloromethane and stirred uniformly to obtain an alcoholamine solution. The alcoholamine solution was slowly added dropwise to the acyl chloride solution, controlling the addition rate to maintain the solution temperature within 3 °C. The addition was completed in approximately 1 hour. After the addition, the ice bath was removed and the mixture was stirred at room temperature for 24 hours. The product was then added dropwise to a mixture of triethylamine and ethanol (volume ratio 1:2), resulting in a white precipitate. The mixture was allowed to stand, and after the precipitate had completely settled, it was filtered by suction. The polymer was then washed several times with a mixture of triethylamine and ethanol and deionized water, and finally dried in a vacuum oven at 70°C for 10 hours to obtain a powdered polymer. The powdered polymer was extruded using a twin-screw extruder at an extrusion temperature of 240°C, granulated, and dried in water to obtain the final polyester product.

[0125] Comparative Example 1: S1. 437 kg / h of terephthalic acid, 437 kg / h of adipic acid, 760 kg / h of 1,4-butanediol, 1.13 kg / h of glycerin, and 0.63 kg / h of tetrabutyl orthotitanate were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to an esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process column was set to 253 kg / h, and the reactor pressure was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, yielding an esterification product BA.

[0126] S2. The esterification product BA was gravity-fed into the pre-polycondensation reactor, and simultaneously 0.27 kg / h of n-butyl titanate and 0.685 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-BA reached a viscosity of 39 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0127] S3. The prepolymer Pre-BA was fed via a melt pump into the disk reactor (i.e., the final polymerization reactor), and the temperature of the final polymerization reactor was set to 250°C, the pressure to 20 Pa, and the reaction time to 2-4 hours. At this point, the reaction product Poly-BA reached a viscosity of 133 ml / g, measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0128] S4. The obtained polyester was introduced into a twin-screw extruder, and simultaneously 5.2 kg / h of hexamethylene diisocyanate (HDI) was metered in, and the temperature was set to 240° C. After a residence time of 3 minutes, the polyester was pelletized using an underwater pelletizer and then dried to obtain the final polyester product.

[0129] Comparative Example 2: S1. 437 kg / h of adipic acid and 404 kg / h of 1,4-butanediol were continuously added to a slurry preparation vessel, and the prepared slurry was continuously supplied to a first esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 135 kg / h, and simultaneously 0.60 kg / h of glycerin and 0.224 kg / h of n-butyl titanate were added. The pressure in the reactor was controlled to 40 kPa (absolute pressure), the temperature to 190°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, yielding an esterification product Ba1.

[0130] 437 kg / h of terephthalic acid and 356 kg / h of 1,4-butanediol were continuously added to a slurry preparation kettle, and the prepared slurry was continuously supplied to a second esterification reactor. The flow rate of 1,4-butanediol via a separate route from the bottom of the process tower was set to 119 kg / h. Simultaneously, 0.53 kg / h of glycerin and 0.406 kg / h of n-butyl titanate were added, and the reactor pressure was controlled to 40 kPa (absolute pressure), the temperature to 240°C, and the residence time to 2 to 4 hours. Water, tetrahydrofuran, and butanediol produced by the reaction were removed, and the resulting esterification product A1 was continuously extracted from the reactor to obtain an esterification product Ba2.

[0131] S2. The two esterification products Ba1 and Ba2 were continuously fed into a mixer at a temperature of 230°C with a residence time of 30 minutes. The mixture flowing out of the mixer was gravity-fed into a preliminary polycondensation reactor. At the same time, 0.27 kg / h of n-butyl titanate and 0.685 kg / h of triphenyl phosphate were added. The temperature was 250°C, the reactor pressure was 2 kPa, and the residence time was 2-3 hours to extract excess butanediol. At this point, the reaction product Pre-BA reached a viscosity of 37 ml / g, as measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0132] S3. The prepolymer Pre-BA was fed via a melt pump into the disk reactor (i.e., the final polymerization reactor), and the temperature of the final polymerization reactor was set to 250°C, the pressure to 20 Pa, and the reaction time to 2-4 hours. At this point, the reaction product Poly-BA reached a viscosity of 128 ml / g, measured in a 1:1 weight ratio phenol / o-dichlorobenzene solution in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

[0133] S4. The obtained polyester was introduced into a twin-screw extruder, and simultaneously 5.2 kg / h of hexamethylene diisocyanate (HDI) was metered in, and the temperature was set to 240° C. After a residence time of 3 minutes, the polyester was pelletized using an underwater pelletizer and then dried to obtain the final polyester product.

[0134] Comparative Example 3: Under the protection of high-purity nitrogen, 2.36 kg of terephthalic acid, 2.36 kg of adipic acid, 4.38 kg of 1,4-butanediol, 6.1 g of glycerin, and 4.9 g of n-butyl titanate were added to the reactor. The temperature was raised to 240°C and maintained at this temperature for 120 minutes. Next, 3.7 g of triphenyl phosphate was added. Within 60 minutes, the pressure inside the reactor was reduced to less than 50 Pa, and the reaction was carried out at 260°C for 60 to 120 minutes. High-purity nitrogen was then filled into the reactor, and 28.1 g of hexamethylene diisocyanate (HDI) was added. The mixture was stirred at a constant temperature of 260°C for 5 minutes before being discharged. [Table 1] TIFF0007784544000003.tif128170

[0135] As can be seen from the above results, the double bond content of the semi-aromatic polyester of the present invention is controlled within the range of 0.55 to 4.5 mmol / kg, and the polyester has high heat retention melt index retention, high Hunter whiteness and good color.

[0136] In Comparative Example 1, a mixed esterification step was used in the entire process, and the polymerization temperature was relatively high, so the aliphatic polyester-derived portion in the semi-aromatic polyester was prone to thermal degradation, resulting in a high double bond content, a very low heat retention melt index retention rate, and poor color.

[0137] In Comparative Example 2, the aliphatic polyester and the aromatic polyester were esterified independently, but the two were still mixed in the post-esterification process. This had some effect on reducing the double bond content, improving the heat retention melt index retention rate and color, but the reaction time of the esterification stage accounted for a small proportion of the total polymerization reaction time, so the improvement effect was limited.

[0138] Comparative Example 3 was produced using a batch process, and the resulting double bond content was high, the heat retention melt index retention rate was low, and the color was poor.

Claims

1. Based on the total molar amount of the first component A, a1) 40 to 60 mol % of at least one aliphatic dicarboxylic acid or a derivative thereof, a2) a first component A comprising 40 to 60 mol % of at least one aromatic dicarboxylic acid or a derivative thereof; A second component B: a semi-aromatic polyester derived from repeating units consisting of a diol having 2 to 12 carbon atoms, the double bond content in the semi-aromatic polyester is 0.55 to 4.5 mmol / kg; Based on the total molar amount of the first component A, the semi-aromatic polyester further comprises 0.01 to 5.0 mol % of a third component C; The semi-aromatic polyester, wherein the third component C is selected from one or more of tartaric acid, citric acid, malic acid, trimethylolpropane, trimethylolethane, pentaerythritol, polyether triol, glycerin, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid anhydride, 1,2,4,5-benzenetetracarboxylic acid, and pyromellitic dianhydride.

2. 2. The semi-aromatic polyester according to claim 1, wherein component a1) is selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,11-undecanedicarboxylic acid, 1,10-decanedicarboxylic acid, undecanedioic acid, 1,12-dodecanedicarboxylic acid, hexadecanedioic acid, eicosanedioic acid or tetracosanedioic acid, or ester derivatives thereof or anhydride derivatives thereof, or a mixture of one or more of these.

3. 2. The semi-aromatic polyester according to claim 1, wherein component a2) is selected from the group consisting of terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, or a mixture of one or more of their ester derivatives or anhydride derivatives.

4. 2. The semi-aromatic polyester according to claim 1, wherein the second component B is selected from one or more of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol.

5. The semi-aromatic polyester according to claim 1, characterized in that the component a1) is adipic acid or an ester derivative thereof or an anhydride derivative thereof, the component a2) is terephthalic acid or an ester derivative thereof or an anhydride derivative thereof, and the second component B is 1,4-butanediol.

6. Based on the total molar amount of the first component A, the semi-aromatic polyester also contains 0.01 to 5.0 mol % of a fourth component D; 2. The semi-aromatic polyester of claim 1, wherein the fourth component D is selected from one or more of isocyanates, isocyanurates, peroxides, epoxides, oxazolines, oxazines, lactams, carbodiimides or polycarbodiimides containing two or more functional groups.

7. 2. The semi-aromatic polyester according to claim 1, wherein the viscosity number of the semi-aromatic polyester is 150 to 350 ml / g, measured in a phenol / o-dichlorobenzene solution in a weight ratio of 1:1 in a constant temperature water bath at 25±0.05°C according to GB / T 17931-1999 standard.

8. 2. The semi-aromatic polyester according to claim 1, wherein the carboxyl group content of the semi-aromatic polyester is 5 to 60 mmol / kg.

9. In weight percentage, 5 to 95 wt. % of the semi-aromatic polyester according to claim 1; 5 to 95% by weight of another polymer; and 0 to 70% by weight of a filler.

10. 10. The application of the semi-aromatic polyester according to claim 1 in the manufacture of a compostable degradable product, characterized in that the compostable degradable product is a fiber, a film or a container.

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