Application of nonmetal organic compound in catalytic synthesis of polyester, polyester and preparation method thereof

Abstract

The invention discloses application of a non-metal organic compound in catalytic synthesis of polyester, the polyester and a preparation method of the polyester, and the non-metal organic compound serves as a polycondensation catalyst and a copolymerization reaction monomer to catalyze a polycondensation reaction between the non-metal organic compound and polyester ester (such as BHET). The non-metal organic compound is a benzimidazole structure derivative containing hydroxyl. The benzimidazole compound is obtained by esterification or ester exchange reaction of a benzimidazole compound and dihydric alcohol, neutralization and purification reaction of esterification liquid. The compound can replace a traditional metal polycondensation catalyst and catalyzes melt polycondensation of the compound and a polyester raw material monomer to prepare metal-catalyst-free copolyester, and the adverse effect of metal catalyst residues is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of polyester synthesis, and in particular to application of a non-metallic organic compound in catalytic synthesis of polyester. Background Art

[0002] Semi-aromatic polyesters, such as PET, PTT and PBT, have excellent mechanical properties, chemical resistance, weather resistance and other comprehensive properties, and are widely used in fiber textiles, packaging, optical films and engineering plastics. Semi-aromatic polyesters are mainly prepared by melt polycondensation of aromatic dicarboxylic acids and aliphatic diols. Traditional methods include PTA direct esterification and DMT transesterification. Taking terephthalic acid and ethylene glycol as an example, the PTA direct esterification method first undergoes an esterification reaction to generate ethylene terephthalate (BHET for short), and then BHET undergoes polycondensation under the action of a metal catalyst to remove a portion of ethylene glycol to generate PET. Taking dimethyl terephthalate and ethylene glycol as an example, the DMT transesterification method first undergoes an esterification reaction under the action of a catalyst to generate ethylene terephthalate (BHET for short), and then BHET undergoes polycondensation under the action of a metal catalyst to remove a portion of ethylene glycol to generate PET. It can be understood that the second step of both methods is a polycondensation reaction, in which metal catalysts have always played a very important role. Suitable polycondensation catalysts can greatly improve the production efficiency of related products.

[0003] At present, the catalysts used in the melt polycondensation reaction of polyester are mainly metal-based catalysts, such as heavy metal antimony catalysts commonly used in PET polyester production, and titanium catalysts commonly used in PBT polyester production. These metal-based catalysts have more or less certain problems in ecological safety or polymerization activity and polyester performance quality. For example, antimony catalysts will cause heavy metal pollution in the later PET fiber dyeing and finishing process; titanium catalysts generally have the disadvantages of easy hydrolysis, poor stability, and aggravated side reactions, resulting in a poor hue of the synthesized polyester (high yellowness). In recent years, with the growing concerns about the residues of metal catalysts in synthetic polymers, polymerization reactions catalyzed by small organic molecules have received unprecedented attention and development.

[0004] In the existing PTA direct esterification technology, patent CN108395526A discloses a flame-retardant anti-melting copolyester based on a benzimidazole structure and a preparation method thereof. First, terephthalic acid and ethylene glycol react to generate (BHET), and then BHET undergoes a polycondensation reaction under the action of a metal catalyst to generate PET. Under the action of the metal catalyst, a third monomer having a benzimidazole structure is copolymerized into the polyester molecular chain as a flame-retardant unit. In the existing DMT transesterification method, patent CN114989406A discloses a novel non-metallic organic transesterification catalyst, under the action of the catalyst, dimethyl terephthalate and ethylene glycol undergo an ester exchange reaction to generate BHET, and then under the action of a metal catalyst, BHET undergoes a polycondensation reaction to generate PET. The above scheme still uses a metal catalyst in the polycondensation reaction process. Summary of the invention

[0005] The present invention aims at the problem of metal catalyst residue in the polycondensation reaction in the polyester synthesis process in the prior art, and provides an application of synthesizing polyester using a non-metallic organic compound as a polycondensation catalyst. The compound can replace the traditional metal polycondensation catalyst, catalyze itself and polyester raw material monomers through melt polycondensation to prepare a copolyester without a metal catalyst, thereby avoiding the adverse effects of metal catalyst residue.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A use of a non-metallic organic compound in catalytic synthesis of polyester, wherein the non-metallic organic compound is used as a polycondensation catalyst and a copolymerization monomer to catalyze the polycondensation reaction between itself and a polyester ester (such as BHET), and the non-metallic organic compound is a hydroxyl-containing benzimidazole structure derivative, and its structural formula is any one of AE:

[0008]

[0009] Wherein, n is an integer of 1 to 7, m is an integer of 1 to 7, R1 is H, halogen, C1 to C6 alkyl or alkoxy, and R2 is phenylene or C1 to C10 alkylene. The non-metallic organic compound prepared by the present invention contains a polymerizable functional group, namely an ester group, which enables it to be used as a copolymerization monomer in the polycondensation process and to be connected to the molecular chain of the polyester through melt polycondensation. At the same time, like BHET, it contains a hydroxyl group at the end, which may reduce the activation energy of the polycondensation process. The hydroxyl group can also form a hydrogen bond with BHET, further reducing the reaction energy barrier, replacing the metal catalyst to catalyze the polycondensation reaction between itself and the polyester ester (such as BHET), and preparing a copolyester, thereby avoiding the adverse effects of a small molecule ester exchange catalyst.

[0010] In some embodiments, the hydroxyl group is any one of hydroxyethyl, hydroxypropyl or hydroxybutyl.

[0011] The preparation method of the non-metallic organic compound comprises the following steps: the benzimidazole compound with the structural formula A1-E1 undergoes esterification or transesterification reaction with a diol, and the esterified liquid after the reaction is neutralized and purified to obtain the hydroxyl-containing benzimidazole structural derivative with the structural formula AE.

[0012]

[0013] Wherein, m is an integer of 1 to 7, R1 is H, halogen, C1 to C6 alkyl or alkoxy, and R2 is phenylene or C1 to C10 alkylene.

[0014] The diol is one of ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,4-pentanediol and 1,4-hexanediol.

[0015] The benzimidazole compound of the structural formula A1-E1 is obtained by cyclizing o-phenylenediamine or its derivatives with an aldehyde compound under the action of a catalyst or an oxidant. Generally speaking, it includes two steps: first, o-phenylenediamine or its derivatives condense with the aldehyde group to form a Schiff base, and then the Schiff base undergoes a ring-closing reaction, and then oxidative dehydrogenation to obtain the benzimidazole compound. Alternatively, o-phenylenediamine or its derivatives are reacted with a carboxylic acid compound in an acidic reagent in the presence of H + Obtained by cyclization under catalysis.

[0016] The esterification liquid obtained after the above esterification reaction is completed can also be directly used as a non-metallic catalyst and copolymerization monomer in the polyester synthesis polycondensation process.

[0017] And / or, the polycondensation reaction is the second polycondensation reaction in the PTA direct esterification method and the DMT ester exchange method, including a pre-polycondensation and a polycondensation process, the pre-polycondensation is carried out at 230-250° C. under low vacuum for 0.20-1.0 hour, and the polycondensation is carried out at 250-280° C. under high vacuum for 1-3 hours.

[0018] The present invention provides a method for synthesizing polyester based on non-metallic organic compounds, comprising the steps of: subjecting a dicarboxylic acid, a diol and the non-metallic organic compound or its esterified liquid to esterification reaction and melt polycondensation reaction to obtain a copolyester without a metal catalyst;

[0019] Or a dicarboxylic acid ester and a diol undergo an ester exchange reaction under the action of a catalyst, and then a non-metallic organic compound or its esterification liquid is added to carry out a melt polycondensation reaction to obtain a copolyester without a metal catalyst;

[0020] The non-metallic organic compound acts as both a polycondensation catalyst and a copolymerization monomer.

[0021] The molar addition amount of the non-metallic organic compound is at least 0.3% of the molar amount of the dicarboxylic acid or carboxylate polymerized monomer. The present invention finds that the molar addition amount of the non-metallic organic compound in the system is more than 0.3 mol% of the molar amount of the dicarboxylic acid or carboxylate polymerized monomer, which can effectively achieve the polycondensation catalytic effect. Since the compound can also be used as a comonomer, the further increase of its content will not cause the problem of polycondensation catalyst residue. Even when the usage amount is within a certain range, it will also have a certain gain effect, achieving the flame retardant and anti-melting droplet and glass transition temperature increase effects as in patent CN108395526A.

[0022] The molar addition amount of the non-metallic organic compound is 0.3-20% of the molar amount of the dicarboxylic acid or carboxylic acid ester polymerization monomer. The dicarboxylic acid is at least one of terephthalic acid, isophthalic acid, and sodium 5-sulfoisophthalic acid, and the dicarboxylic acid ester is at least one of the diol esters of terephthalic acid or the esters obtained by direct esterification of the above dicarboxylic acids and diols.

[0023] The molar addition amount of the non-metallic organic compound is 0.3-10% of the molar amount of the dicarboxylic acid or carboxylic acid ester polymerization monomer. This is mainly because due to the large rigid ring structure of the non-metallic organic compound itself, excessive introduction will reduce the regularity of the polyester molecular chain, seriously destroy the crystallization performance of the polyester, and will not be used in later applications.

[0024] And / or, the esterification reaction is carried out at 180-240° C. for 1.0-2.5 h under a certain pressure.

[0025] The preparation process of the above copolyester is the same as the conventional direct esterification method, DMT ester exchange method, or BHET direct polycondensation method for preparing polyester. The non-metallic organic compound or its esterification liquid can be added to the polymerization system together with the reaction raw materials before esterification, or can be added to the polymerization system after the esterification (or ester exchange) is completed and before the polycondensation begins. Usually, the latter has a better effect.

[0026] The molar ratio of the dicarboxylic acid ester, the diol, and the non-metallic organic compound is determined according to conventional knowledge in the art, usually in a ratio of the total molar amount of carboxyl and ester groups to the molar amount of hydroxyl groups of 1.0-1.3:1. The diol structure is as follows:

[0027] HO-R 10 -OH

[0028] In the formula, R 10 represents a C2-C12 alkylene group, an alkylidene group or an alkoxy group;

[0029] In some embodiments, the diol includes at least one of ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, and polyethylene glycol;

[0030] And / or, a functional additive is added to the preparation method of the polyester synthesized based on the non-metallic organic catalyst. The functional additive includes a stabilizer and a titanium dioxide digester, and the stabilizer includes one or more of trimethyl phosphate, triethyl phosphate, tripropyl phosphate, triisopropyl phosphate, tributyl phosphate, triphenyl phosphate, tripropyl octyl phosphate, phosphoric acid and phosphorous acid. Whether to add a functional additive and the content thereof are selected according to the actual product usage requirements (bottle flakes, bright, semi-digested, fully matte).

[0031] The present invention also provides a metal-catalyst-free polyester synthesized based on non-metallic organic compounds. During the preparation of the polyester, the non-metallic organic compounds are used as both polycondensation catalysts and copolymerization monomers. The intrinsic viscosity of the obtained polyester is 0.50 to 0.80 dL / g. The polyester does not contain any metal catalyst, and the polyester macromolecular structure contains any of the following copolymerization structural units A2-E2.

[0032]

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The present invention applies non-metallic organic compounds to catalytic polyester synthesis, and finds that they can also serve as polycondensation catalysts, and when the addition amount is above 0.3 mol%, an ideal catalytic effect can be achieved without other metal catalysts, and they can replace metal catalysts to obtain high-quality polyester without catalytic metal residues.

[0035] 2. The non-metallic organic catalyst in the present invention can not only catalyze the synthesis of polyester, but also copolymerize with the polymer raw material monomer in the polycondensation stage because the non-metallic organic compound has a polymerizable functional group, and is connected to the macromolecular chain of the copolyester, thereby reducing the side effects caused by the residual non-metallic organic small molecule catalyst. Even when the usage is within a certain range, it will also have a certain gain effect, achieving the effects of flame retardancy, anti-melting droplet resistance and increasing the glass transition temperature as in patent CN108395526A.

[0036] 3. The present invention provides a polyester without metal catalyst and a preparation method thereof, which solves the long-standing problem of metal catalyst residue in polyester, has good application prospects, and meets the huge demand for green and sustainable development of the polyester industry. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art can make modifications or equivalent substitutions based on the understanding of the technical scheme of the present invention without departing from the spirit and scope of the technical scheme of the present invention, and all should be included in the protection scope of the present invention.

[0038] The non-metallic organic compounds used in the following specific embodiments are purchased or prepared according to the literature, and other raw materials are purchased from the market.

[0039] In addition, it is worth noting that the intrinsic viscosity [η] of the copolymers obtained in the following examples and the comparative copolymers were prepared using phenol / 1,1,2,2-tetrachloroethane (1:1, v:v) as solvent to prepare a solution with a concentration of 5 g / dL, and tested using an Ubbelohde viscometer at 25°C.

[0040] Example 1

[0041] Preparation of 2-(3,5-dimethoxycarbonylphenyl)-1H-benzimidazole: Dissolve equimolar 3,5-dimethylbenzoic acid and o-phenylenediamine in polyphosphoric acid, react at 170°C for 12 hours, neutralize, and recrystallize from ethanol to obtain 2-(3,5-dimethylphenyl)-1H-benzimidazole, which is then oxidized with alkaline potassium permanganate solution to obtain 2-(3,5-dimethoxycarbonylphenyl)-1H-benzimidazole. The obtained 2-(3,5-dimethoxycarbonylphenyl)-1H-benzimidazole is esterified with ethylene glycol under the catalysis of concentrated sulfuric acid. Neutralize, remove the solvent, and purify to obtain 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole.

[0042] Preparation of polyester:

[0043] 498g of terephthalic acid, 210mL of ethylene glycol and 3.33g of 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole (equivalent to 0.3% of the mole of PTA) were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then the temperature was gradually raised to 240°C, vacuum was drawn, and low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.50 dL / g.

[0044] Example 2

[0045] 498g of terephthalic acid, 210mL of ethylene glycol and 5.55g of 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole (equivalent to 0.5% of the mole of PTA) were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then the temperature was gradually raised to 240°C, vacuum was drawn, and low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.60dL / g.

[0046] Example 3

[0047] 498g of terephthalic acid, 210mL of ethylene glycol and 11.1g of 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole (equivalent to 1% of the mole of PTA) were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then the temperature was gradually raised to 240°C, vacuum was drawn, and low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.67dL / g.

[0048] Example 4

[0049] 498g of terephthalic acid, 7.5g of sodium isophthalate-5-sulfonate, 220mL of ethylene glycol and 33.3g of 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole (equivalent to 3% of the mole of PTA) were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then the temperature was gradually raised to 240°C, vacuum was drawn, and low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.71dL / g.

[0050] Example 5

[0051] 498g of terephthalic acid, 220mL of ethylene glycol and 33.3g of 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole (equivalent to 3% of the mole of PTA) were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then the temperature was gradually raised to 240°C, vacuum was drawn, and low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.80dL / g.

[0052] Example 6

[0053] 498g of terephthalic acid, 230mL of ethylene glycol, 111g of 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole (equivalent to 10% of the mole of PTA) and a small amount of trimethyl phosphite were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then the temperature was gradually raised to 240°C, vacuum was drawn, and low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.75dL / g.

[0054] Example 7

[0055] 498g of terephthalic acid, 250mL of ethylene glycol, 444g of 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole (equivalent to 20% of the mole of PTA) and a small amount of trimethyl phosphite were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then the temperature was gradually raised to 240°C, vacuum was drawn, and low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.72dL / g.

[0056] Example 8

[0057] 498g of terephthalic acid, 288mL of 1,3-propylene glycol and 33.3g of 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole (equivalent to 3% of the mole of PTA) were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then the temperature was gradually raised to 240°C, vacuum was drawn, and low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.70dL / g.

[0058] Example 9

[0059] 498g of terephthalic acid, 320mL of 1,4-butanediol and 33.3g of 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole (equivalent to 3% of the mole of PTA) were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then the temperature was gradually raised to 240°C, vacuum was drawn, and low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.78dL / g.

[0060] Example 10

[0061] 498g of terephthalic acid and 230mL of ethylene glycol were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then 22.2g of 2-(3,5-dihydroxyethoxycarbonylphenyl)-1H-benzimidazole (equivalent to 2% of the mole of PTA) was added, the temperature was gradually raised to 240°C, vacuum was drawn, low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and the material was discharged. The intrinsic viscosity [η] of the polyester was 0.80dL / g.

[0062] Embodiment 11

[0063] Preparation of 2-(4-hydroxyethoxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid ethylene glycol ester: dissolve equimolar amounts of methyl paraformylbenzoate, methyl 3,4-diaminobenzoate and sodium metabisulfite in DMF, react at 130°C for 12 hours, remove the solvent, and recrystallize from ethanol to obtain methyl 2-(4-methoxycarbonylphenyl)-1H-benzimidazole-5-carboxylate. The obtained methyl 2-(4-methoxycarbonylphenyl)-1H-benzimidazole-5-carboxylate is reacted with ethylene glycol under the action of DBU catalyst to obtain ethylene glycol 2-(4-hydroxyethoxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid ethylene glycol ester.

[0064] Preparation of polyester:

[0065] 498 g of terephthalic acid and 230 mL of ethylene glycol were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230° C. to start the esterification reaction, and the reaction was maintained for 2 hours. Then 3.33 g of 2-(4-hydroxyethoxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid ethylene glycol ester (equivalent to 0.3% of the mole of PTA) was added, the temperature was gradually raised to 240° C., vacuum was drawn, low vacuum polycondensation was carried out at 240-260° C. for 0.2 to 1 hour, and then high vacuum polycondensation was carried out at 260-280° C. (pressure <80 Pa) for 1.8 to 3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.61 dL / g

[0066] Example 12

[0067] 498g of terephthalic acid and 230mL of ethylene glycol were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then 5.55g of 2-(4-hydroxyethoxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid ethylene glycol ester (equivalent to 0.5% of the mole of PTA) was added, the temperature was gradually raised to 240°C, vacuum was drawn, low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.65dL / g.

[0068] Example 13

[0069] 498g of terephthalic acid and 230mL of ethylene glycol were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then 11.1g of 2-(4-hydroxyethoxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid ethylene glycol ester (equivalent to 1% of the mole of PTA) was added, the temperature was gradually raised to 240°C, vacuum was drawn, low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and the material was discharged. The intrinsic viscosity [η] of the polyester was 0.69dL / g.

[0070] Embodiment 14

[0071] 582g of dimethyl terephthalate, 360mL of ethylene glycol and 2.9g of 1-ethyl-3-methylimidazole acetate were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 190-230°C to start the transesterification reaction, and the reaction was maintained for 2 hours, and then 11.1g of 2-(4-hydroxyethoxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid ethylene glycol ester (equivalent to 1% of the mole of PTA) was added, the temperature was gradually raised to 240°C, vacuum was drawn, low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and the material was discharged. The intrinsic viscosity [η] of the polyester was 0.67dL / g.

[0072] Embodiment 15

[0073] 582g of dimethyl terephthalate, 360mL of ethylene glycol and 3.5g of 1-ethyl-3-methylimidazolium dibenzo[c,e][1,2]oxyphosphinate were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 190-230°C to start the transesterification reaction, and the reaction was maintained for 2 hours, and then 11.1g of 2-(4-hydroxyethoxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid ethylene glycol ester (equivalent to 1% of the mole of PTA) was added, the temperature was gradually raised to 240°C, vacuum was drawn, low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and the material was discharged. The intrinsic viscosity [η] of the polyester was 0.65dL / g.

[0074] Example 16

[0075] Esterified liquid of 2-(4-hydroxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid: dissolve equimolar amounts of p-formylbenzoic acid, 3,4-diaminobenzoic acid and sodium metabisulfite in DMF, react at 130°C for 12 hours, remove the solvent, and recrystallize from ethanol to obtain 2-(4-hydroxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid. Esterify the obtained 2-(4-hydroxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid with excess ethylene glycol at 200-230°C for 3 hours to obtain the esterified liquid of 2-(4-hydroxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid, which can be directly used for polymerization without separation.

[0076] Preparation of polyester:

[0077] 498g of terephthalic acid and 230mL of ethylene glycol were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours, and then a certain amount of esterification liquid of 2-(4-hydroxycarbonylphenyl)-1H-benzimidazole-5-carboxylic acid (calculated as solute, equivalent to 2% of PTA mole) was added, the temperature was gradually raised to 240°C, vacuum was drawn, low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.68dL / g.

[0078] Embodiment 17

[0079] Preparation of 2,2'-(1,3-phenylene)bis(1H-benzimidazole-5-carboxylic acid ethylene glycol ester) esterification liquid: dissolve isophthalaldehyde, 3,4-diaminobenzoic acid and sodium metabisulfite in a stoichiometric ratio in DMF, react at 130°C for 12 hours, remove the solvent, and recrystallize with ethanol to obtain 2,2'-(1,3-phenylene)bis(1H-benzimidazole-5-carboxylic acid). The obtained 2,2'-(1,3-phenylene)bis(1H-benzimidazole-5-carboxylic acid) is esterified with excess ethylene glycol at 200-230°C for 3 hours to obtain 2,2'-(1,3-phenylene)bis(1H-benzimidazole-5-carboxylic acid ethylene glycol ester) esterification liquid. The esterification liquid does not need to be separated and purified and is directly used for polymerization.

[0080] Preparation of polyester:

[0081] 498g of terephthalic acid and 230mL of ethylene glycol were added to the reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the reaction was maintained for 2 hours. Then a certain amount of esterification liquid of 2,2'-(1,3-phenylene)bis(1H-benzimidazole-5-carboxylic acid ethylene glycol ester) was added (calculated as solute, taking 3% of the mole of PTA), the temperature was gradually raised to 240°C, vacuum was drawn, low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and then the material was discharged. The intrinsic viscosity [η] of the polyester was 0.66dL / g

[0082] Comparative Example 1

[0083] 498g of terephthalic acid and 230mL of ethylene glycol were added to a reaction kettle, nitrogen was filled to remove the air in the kettle, the temperature was raised to 200-230°C to start the esterification reaction, and the temperature was maintained for 2 hours, the temperature was gradually raised to 240°C, vacuum was drawn, and low vacuum polycondensation was carried out at 240-260°C for 0.2-1 hour, and then high vacuum polycondensation was carried out at 260-280°C (pressure <80Pa) for 1.8-3.0 hours, and the material was discharged. Finally, no polyester was obtained.

Claims

1. Application of a non-metallic organic compound in catalytic synthesis of polyester, characterized in that: The non-metallic organic compound is used as a polycondensation catalyst and copolymerization monomer in the process of synthesizing polyester; the non-metallic organic compound is a hydroxyl-containing benzimidazole structure derivative, and its structural formula is any one of AE: Wherein, n is an integer of 1 to 7, m is an integer of 1 to 7, R1 is H, halogen, C1 to C6 alkyl or alkoxy, and R2 is phenylene or C1 to C10 alkylene.

2. The use of the non-metallic organic compound in catalytic synthesis of polyester according to claim 1, characterized in that: The hydroxyl group is any one of hydroxyethyl, hydroxypropyl or hydroxybutyl.

3. The use of the non-metallic organic compound in catalytic synthesis of polyester according to claim 1, characterized in that: The benzimidazole compound with the structural formula A1-E1 undergoes esterification or transesterification reaction with a diol, and the esterified liquid after the reaction is neutralized and purified to obtain the hydroxyl-containing benzimidazole structural derivative with the structural formula AE.

4. The method for preparing polyester based on the non-metallic organic compound according to claim 1, characterized in that: The dicarboxylic acid, the diol and the non-metallic organic compound or the esterified liquid thereof are subjected to esterification reaction and melt polycondensation reaction to obtain a copolyester without a metal catalyst; Or a dicarboxylic acid ester and a diol undergo an ester exchange reaction under the action of a catalyst, and then a non-metallic organic compound or its esterification liquid is added to carry out a melt polycondensation reaction to obtain a copolyester without a metal catalyst; The non-metallic organic compound acts as both a polycondensation catalyst and a copolymerization monomer.

5. The method for preparing polyester from non-metallic organic compounds according to claim 4, characterized in that: The molar amount of the non-metallic organic compound added is at least 0.3% of the molar amount of the dicarboxylic acid or carboxylic acid ester polymerization monomer.

6. The method for preparing polyester from non-metallic organic compounds according to claim 4, characterized in that: The molar amount of the non-metallic organic compound added is 0.3-20% of the molar amount of the dicarboxylic acid or carboxylate polymerization monomer; And / or, the esterification reaction is carried out at 180-240° C. for 1.0-2.5 h; And / or, the polycondensation reaction includes a pre-polycondensation and a polycondensation process, the pre-polycondensation is carried out at 230-250° C. under low vacuum for 0.20-1.0 hour, and the polycondensation is carried out at 250-280° C. under high vacuum for 1-3 hours; and / or, the non-metallic organic compound or its esterified liquid is added to the polymerization system before esterification or before polycondensation begins after the esterification is completed; And / or, the non-metallic organic compound or its esterified liquid is added into the polymerization system before the transesterification or before the polycondensation starts after the transesterification.

7. The method for preparing polyester from non-metallic organic compounds according to claim 4, characterized in that: Functional additives are also added into the raw materials, and the functional additives include titanium dioxide matting agent and stabilizer.

8. The polyester synthesized by the method according to any one of claims 4 to 7, characterized in that: The polyester does not contain any metal catalyst, and any one of the following copolymer structural units A1-E1 exists in the macromolecular structure.

9. The polyester according to claim 7, characterized in that The copolymerization structural unit is 0.3-20% of the structural unit of terephthalic acid, the intrinsic viscosity of the obtained polyester is 0.50-0.80 dL / g, and the polyester does not contain any metal catalyst.

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