Preparation of a monomer containing a three-membered ring for preparing a PBT copolyester which can be degraded in water quickly and a preparation method thereof

Abstract

The application discloses a method for preparing modified PBT copolyester by using a ternary ring monomer, and raw materials are N,N'-trans-1,4-cyclohexane-bis (pyrrolidone-4-carboxylic acid methyl ester), 1,4-butanediol and terephthalic acid, a tetrabutyl titanate is used as a catalyst, and condensation polymerization is carried out under nitrogen protection, high temperature, high vacuum degree and solvent-free conditions to obtain PBC x BT y Copolyester. The application has the advantages that diester monomers synthesized from renewable resources are used, raw materials are widely available, reaction conditions are mild, the synthesis process is easy to operate, the prepared copolyester has adjustable performance, high glass transition temperature and good thermal stability, industrial production is possible, the degradation speed of PBT in water can be improved, and the application of PBT in the field of degradable materials is expanded.

Description

Technical Field

[0001] This invention belongs to the field of polymer material synthesis technology, and relates to a method for preparing rapidly hydrolyzable PBT copolyester using monomers with rigid multi-rings. Specifically, it relates to a method for preparing rapidly water-degradable PBT copolyester using monomers containing three-rings and the same. Background Technology

[0002] Poly(butylene terephthalate) (PBT) is a high-performance polyester material with advantages such as high rigidity and good thermal stability, and is mainly used in electronics, automobiles, and machinery. However, it is difficult to degrade, especially under natural conditions, leading to serious white pollution. Conventionally, various methods are used to improve the water degradation performance of PBT. These include: developing new biodegradable polyester materials to replace PBT; using chemical modification methods, such as extending the chain of PBT with petroleum-based chain extenders; and using physical modification methods, such as blending PBT with ethylene-acrylate copolymers or glycidyl methacrylate-grafted polyolefin elastomers. However, these methods have many problems: high raw material costs, poor thermal and mechanical properties after material modification, and the fact that the raw materials still come from non-renewable petrochemical byproducts.

[0003] How to use raw materials derived from green biomass to improve the toughness of PBT polyester materials is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing modified PBT copolyester using diester monomers containing three-membered rings. This preparation method has a simple synthesis process, is easy to operate, has a high yield, is green and environmentally friendly, and is easy to promote industrially.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] This invention provides a class of rapidly water-degradable PBT copolyesters, comprising N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene diester repeating units as shown in formula (a) and butylene terephthalate repeating units as shown in formula (b).

[0007] Its chemical name is: poly(butylene terephthalate-co-N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester)butylene);

[0008]

[0009]

[0010] The number-average molecular weight of the PBT copolyester is not less than 20,000 g / mol;

[0011] The PBT copolyester that can be rapidly degraded in water has a degradation rate of no less than 10% in water after 100 days.

[0012] Furthermore, taking the rapidly water-degradable PBT copolyester as 100%, the N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene diester repeating unit accounts for 5%-40% in molar proportion; the remainder is butylene terephthalate repeating unit.

[0013] Furthermore, taking the rapidly water-degradable PBT copolyester as 100%, the N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene diester repeating unit accounts for 20%-30% in molar proportion; the remainder is butylene terephthalate repeating unit.

[0014] Secondly, this invention discloses a method for preparing a rapidly water-degradable PBT copolyester, wherein the copolymer is obtained by condensation polymerization of N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester), 1,4-butanediol and terephthalic acid under solvent-free conditions.

[0015] Furthermore, the preparation method of rapidly water-degradable PBT copolyester includes the following steps:

[0016] N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester), 1,4-butanediol, and terephthalic acid were added to a closed reactor, and a catalyst was added. The transesterification reaction, pre-condensation reaction, and condensation reaction were carried out in sequence to obtain the PBT copolyester that can be rapidly degraded in water.

[0017] Furthermore, the molar ratio of terephthalic acid, N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester) and 1,4-butanediol is 1:1.8-3, and a more preferred molar ratio is 1:2.

[0018] Furthermore, the catalyst is tetrabutyl titanate, and its addition amount is 0.03% to 0.45% of the total molar amount of N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester), 1,4-butanediol and terephthalic acid.

[0019] Furthermore, the transesterification reaction is carried out at a temperature of 180-230°C for 5-10 hours.

[0020] Furthermore, the polycondensation reaction is carried out under a vacuum of less than or equal to 100 Pa, the polycondensation reaction temperature is 230-260℃, and the polycondensation reaction time is 2-10 h.

[0021] Furthermore, the transesterification reaction is carried out under nitrogen protection.

[0022] The beneficial effects of this invention are as follows:

[0023] 1) This invention utilizes renewable monomers to modify PBT polyester, resulting in polyester with good thermal stability and high molecular weight, which can reduce dependence on petroleum resources.

[0024] 2) The method for synthesizing polyester in this invention is green and environmentally friendly, with a simple and easy-to-operate synthesis process, high synthesis yield, and the potential for large-scale production.

[0025] 3) The properties of the copolyester material provided by the present invention are adjustable. The addition of diester monomers can make PBT copolyester degrade rapidly, which makes up for the disadvantage of slow hydrolysis of PBT. Furthermore, the hydrolysis rate can be adjusted by controlling the content of terephthalic acid and N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester).

[0026] 4) N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester) has a three-membered ring structure. The raw material for its synthesis comes from biomass, which is a renewable resource. Moreover, the pyrrolidone ring has high hydrophilicity. When it is copolymerized with PBT, it not only does not affect the thermal and mechanical properties of PBT polyester itself, but also makes up for its disadvantage of being difficult to hydrolyze, which can expand the application of PBT polyester in the field of biodegradable materials. Attached Figure Description

[0027] Figure 1 The DSC melt curve of Example 1;

[0028] Figure 2 The DSC melt curve for Example 2;

[0029] Figure 3 The curve showing the change in residual mass after degradation over time in Example 1;

[0030] Figure 4 The curve shows the change in the remaining mass after degradation over time in Example 2. Detailed Implementation

[0031] The following embodiments are specific illustrations of the present invention. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential adjustments and improvements made to the present invention by those skilled in the art are within the scope of protection of the present invention.

[0032] In the following embodiments, unless otherwise specified, all raw materials are basically commercially available or prepared by conventional methods in the art.

[0033] In the following examples, thermal transformation analysis was performed using a TA Q2000 differential scanning calorimeter at a heating rate of 10 °C / min under a nitrogen atmosphere, with a temperature range of -70 to 280 °C.

[0034] In the following embodiments, the water degradation test involves molding the sample into a sheet of 5×5×1mm, placing the sheet in a glass bottle containing 15mL of deionized water, and shaking the glass bottle in a shaker at room temperature for 100 days to test its water degradation performance.

[0035] In the examples, the rapidly water-degradable PBT copolymer is poly(butylene terephthalate-co-N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester)butylene), abbreviated as PBC. x BT y B, C, and T represent 1,4-butanediol, N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylate methyl ester), and terephthalic acid, respectively, and x and y are the molar proportions of N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylate methyl ester) and terephthalic acid in the copolyester (*100); as in Example 1, PBC 20 BT 80 This indicates that the molar percentage of PBC units in the PBT copolyester is 20%; and the molar percentage of BT units is 80%.

[0036] Example 1

[0037] PBC 20 BT 80 Preparation of copolyesters:

[0038] 1) PBC was prepared by condensation polymerization of diester monomers N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester), 1,4-butanediol, and terephthalic acid. 20 BT 80 Copolyester with an alkyd molar ratio of 2:1;

[0039] 2) Weigh 0.2 mol of N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester), 0.8 mol of terephthalic acid and 2.0 mol of 1,4-butanediol according to the initially designed alcohol-acid molar ratio, place them in a well-sealed round-bottom flask, add 0.01 mol of tetrabutyl titanate catalyst dropwise, and react for 6 h at a transesterification temperature of 220 °C under a nitrogen atmosphere.

[0040] 3) Adjust the vacuum to 60 Pa, raise the temperature to 240 °C, and carry out a polycondensation reaction for 6 hours to obtain the copolyester.

[0041] Example 2

[0042] PBC 30 BT 70 Preparation of copolyesters:

[0043] 1) PBC was prepared by condensation polymerization of diester monomers N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester), 1,4-butanediol, and terephthalic acid. 30 BT 70 Copolyester with an alkyd molar ratio of 2:1;

[0044] 2) Weigh 0.3 mol of N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester), 0.7 mol of terephthalic acid and 2.0 mol of 1,4-butanediol according to the initially designed alcohol-acid molar ratio, place them in a well-sealed round-bottom flask, add 0.01 mol of tetrabutyl titanate catalyst dropwise, and react for 6 h at a transesterification temperature of 220 °C under a nitrogen atmosphere.

[0045] 3) Adjust the vacuum to 60 Pa, raise the temperature to 240 °C, and carry out a polycondensation reaction for 6 hours to obtain the copolyester.

[0046] Test Example 1

[0047] PBC 20 BT 80 Copolyester DSC test:

[0048] 1) Weigh 5-10 mg of the copolyester prepared in Example 1 and place it in a differential scanning calorimeter to test the melt curve;

[0049] 2) Set the program to “heat up-isothermal-cool down-isothermal-heat up”, with a temperature test range of -70 to 280℃ and a heating and cooling rate of 10℃ / min, and obtain the melting curve.

[0050] Figure 1 For PBC 20 BT 80 The DSC melt curve of the copolyester shows the glass transition temperature (T) of the copolyester. g The temperature was 60.1℃, and the PBT temperature was T. g The temperature was 50.3℃. (PBC) 20 BT 80 T of copolyester g Higher than PBT.

[0051] Test Example 2

[0052] PBC 30 BT 70 Copolyester DSC test:

[0053] 1) Weigh 5-10 mg of the copolyester prepared in Example 2 and place it in a differential scanning calorimeter to test the melt curve;

[0054] 2) Set the program to “heat up-isothermal-cool down-isothermal-heat up”, with a temperature test range of -70 to 280℃ and a heating and cooling rate of 10℃ / min, and obtain the melting curve.

[0055] Figure 2 For PBC 30 BT 70 The DSC melt curve of the copolyester shows the glass transition temperature (T) of the copolyester. g The temperature was 62.7℃, and the PBT temperature was 10℃. g The temperature was 50.3℃. (PBC) 30 BT 70 T of copolyester g Higher than PBT.

[0056] Test Example 3

[0057] PBC 20 BT 80 Copolyester water degradation performance test:

[0058] 1) PBC sample 20 BT 80 The copolyester was molded and cut into 5×5×1mm sheets, and the sheets were placed in a glass bottle containing 15mL of deionized water for water degradation testing.

[0059] 2) Place the glass bottle in a shaker at room temperature and shake for 100 days. Every so often, take out the sheet, dry it, weigh it, and record the percentage decrease in quality.

[0060] Figure 3 For PBC 20 BT 80 The curves showing the change in residual mass of copolyesters after degradation over time indicate that PBT remained relatively stable after 100 days of water degradation, without any decrease in mass, while PBC... 20 BT 80 As the copolyester degrades, its mass decreases; after 100 days, the mass decreases by 16%, demonstrating rapid hydrolysis.

[0061] Test Example 4

[0062] PBC 30 BT 70 Copolyester water degradation performance test:

[0063] 1) PBC sample 30 BT 70The copolyester was molded and cut into 5×5×1mm sheets, and the sheets were placed in a glass bottle containing 15mL of deionized water for water degradation testing.

[0064] 2) Place the glass bottle in a shaker at room temperature and shake for 100 days. Every so often, take out the sheet, dry it, weigh it, and record the percentage decrease in quality.

[0065] Figure 4 For PBC 30 BT 70 The curves showing the change in residual mass of copolyesters over time after degradation reveal that PBT remained relatively stable after 100 days of water degradation, without significant mass loss, while PBC... 30 BT 70 The copolyester rapidly degrades as it degrades, decreasing by 20% after 100 days, demonstrating its rapid hydrolytic degradation characteristics. The hydrolysis rate accelerates with increasing N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester) content.

Claims

1. A type of PBT copolyester that is rapidly degradable in water, characterized in that, Including the N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylate methyl ester) butylene diester as shown in formula (a) and the butylene terephthalate repeating unit as shown in formula (b), the chemical name of which is: poly(butylene terephthalate-co-N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylate methyl ester) butylene diester); (a) (b) The PBT copolyester has a number-average molecular weight of not less than 20,000 g / mol; and a degradation rate in water of not less than 10% after 100 days. Based on 100% of the sum of the molar numbers of N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylate methyl ester) butylene diester repeating units and butylene terephthalate repeating units in the PBT copolyester, wherein the molar percentage of the N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylate methyl ester) butylene diester repeating units is 5%-40%; the remainder is butylene terephthalate repeating units.

2. The rapidly water-degradable PBT copolyester according to claim 1, characterized in that, The N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester) butylene diester repeating unit accounts for 20%-30% of the total; the remainder is butylene terephthalate repeating unit.

3. A method for preparing a rapidly water-degradable PBT copolyester according to any one of claims 1-2, characterized in that, Includes the following steps: N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester), 1,4-butanediol, and terephthalic acid were added to a closed reactor, and a catalyst was added. The transesterification reaction, pre-condensation reaction, and condensation reaction were carried out in sequence to obtain the PBT copolyester that can be rapidly degraded in water. The molar ratio of terephthalic acid, N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester) and 1,4-butanediol is 1:1.8-3. The catalyst is tetrabutyl titanate, and its addition amount is 0.03%~0.45% of the total molar amount of N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester), 1,4-butanediol and terephthalic acid. The transesterification reaction was carried out at a temperature of 180-230℃ for 5-10 hours. The polycondensation reaction is carried out under a vacuum of less than or equal to 100 Pa, at a temperature of 230-260℃, and for a time of 2-10 h.

4. The preparation method according to claim 3, characterized in that, The molar ratio of terephthalic acid, N,N'-trans-1,4-cyclohexane-bis(pyrrolidone-4-carboxylic acid methyl ester) and 1,4-butanediol is 1:2.

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