Preparation method of PET polyester material with high creep resistance

Abstract

The present invention relates to a preparation method of a high creep resistance PET polyester material, comprising the following steps: dimethyl terephthalate is mixed with ethylene glycol and a catalyst is added, the temperature is raised to 160-220°C for reaction for 1-2h, and ethylene terephthalate is synthesized by transesterification; trimethylolpropane and pyromellitic anhydride are mixed and reacted, and the reaction product is used as a dynamic crosslinking agent for standby; the dynamic crosslinking agent is mixed with ethylene terephthalate and the temperature is raised to 240-300°C, and a catalyst is added for polymerization reaction for 3.5-5h to form dynamic crosslinked polyethylene terephthalate. The present invention utilizes dynamic bonds to generate dynamic crosslinking between straight-chain polymer chains. When the service temperature of the material is much lower than the critical temperature of the dynamic bond exchange, the relaxation time of the dynamic crosslinking tends to infinity, and the dynamic crosslinking is similar to permanent chemical crosslinking, which can effectively limit the mutual slip phenomenon between polymer chains, and significantly enhance the creep resistance of thermoplastic materials.

Description

Technical Field

[0001] The invention relates to the technical field of PET polyester material preparation, and in particular to a method for preparing a high creep resistance PET polyester material. Background Art

[0002] The polymer material PET polyester is inevitably subjected to external forces during service. When the PET polyester material is subjected to external forces, the polymer chains are prone to mutual slippage and creep due to the weak interaction between the internal chains of the straight-chain polymer material, resulting in material deformation and failure, which seriously limits its application in many different fields. In order to improve the creep resistance of PET polyester, it is necessary to enhance the interaction between polymer chains. To this end, the present invention improves the creep resistance of PET polyester material by dynamic crosslinking. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing a PET polyester material with high creep resistance, so as to solve the problem of poor creep resistance of the PET polyester material in the prior art.

[0004] The present invention provides a method for preparing a high creep resistance PET polyester material, comprising the following steps:

[0005] (1) mixing dimethyl terephthalate and ethylene glycol, adding a catalyst, heating to 160-220° C. for reaction for 1-2 hours, and synthesizing ethylene terephthalate by transesterification;

[0006] (2) mixing trimethylolpropane and pyromellitic anhydride and reacting them, and using the reaction product as a dynamic crosslinking agent for standby use;

[0007] (3) The dynamic crosslinking agent is mixed with ethylene terephthalate and the temperature is raised to 240-300° C. A catalyst is added to carry out polymerization reaction for 3.5-5 hours to form dynamically crosslinked polyethylene terephthalate.

[0008] Furthermore, the catalyst in step (1) is cadmium acetate and antimony trioxide.

[0009] Furthermore, in step (1), the mass ratio of dimethyl terephthalate to ethylene glycol is 23:77-35:65.

[0010] Furthermore, in the step (2), the mass ratio of trimethylolpropane to pyromellitic anhydride is 35:65-55:45.

[0011] Furthermore, the catalyst in step (3) is antimony trioxide.

[0012] Furthermore, the molar amount of the dynamic crosslinking agent in step (3) is 0.4%-0.7% of the molar amount of ethylene terephthalate.

[0013] The beneficial effects of adopting the above technical solution of the present invention are:

[0014] The present invention utilizes dynamic bonds to generate dynamic crosslinking between linear polymer chains. When the service temperature of the material is much lower than the critical temperature of the dynamic bond exchange, the relaxation time of the dynamic crosslinking tends to infinity. The dynamic crosslinking is similar to permanent chemical crosslinking and can effectively limit the mutual slippage between polymer chains, significantly enhance the creep resistance of thermoplastic materials, and expand the application field of the materials. At the same time, since the dynamic crosslinking can be dissociated at high temperature and has the function of repeatable processing, the PET polyester material retains the recycling performance while improving the creep resistance. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0016] Example 1

[0017] (1) dimethyl terephthalate and ethylene glycol were mixed in a mass ratio of 29:71, cadmium acetate and antimony trioxide were added, and the temperature was raised to 200° C. for reaction for 2 h to synthesize ethylene terephthalate through ester exchange;

[0018] (2) mixing trimethylolpropane and pyromellitic anhydride in a mass ratio of 45:55 and reacting the mixture, and using the reaction product as a dynamic crosslinking agent for standby use;

[0019] (3) The dynamic crosslinking agent is mixed with ethylene terephthalate and the temperature is raised to 300° C. Antimony trioxide is added to carry out polymerization reaction for 3.5 hours to form dynamically crosslinked polyethylene terephthalate, wherein the molar number of the dynamic crosslinking agent is 0.4% of the molar number of the ethylene terephthalate.

[0020] Example 2

[0021] (1) dimethyl terephthalate and ethylene glycol were mixed in a mass ratio of 29:71, cadmium acetate and antimony trioxide were added, and the temperature was raised to 200° C. for reaction for 2 h to synthesize ethylene terephthalate through ester exchange;

[0022] (2) mixing trimethylolpropane and pyromellitic anhydride in a mass ratio of 48:52 and reacting the mixture, and using the reaction product as a dynamic crosslinking agent for standby use;

[0023] (3) The dynamic crosslinking agent is mixed with ethylene terephthalate and the temperature is raised to 280° C. Antimony trioxide is added to carry out polymerization reaction for 4 hours to form dynamically crosslinked polyethylene terephthalate, wherein the molar number of the dynamic crosslinking agent is 0.5% of the molar number of the ethylene terephthalate.

[0024] Example 3

[0025] (1) dimethyl terephthalate and ethylene glycol were mixed in a mass ratio of 29:71, cadmium acetate and antimony trioxide were added, and the temperature was raised to 200° C. for reaction for 2 h to synthesize ethylene terephthalate through ester exchange;

[0026] (2) mixing trimethylolpropane and pyromellitic anhydride in a mass ratio of 50:50 and reacting the mixture, and using the reaction product as a dynamic crosslinking agent for standby use;

[0027] (3) The dynamic crosslinking agent is mixed with ethylene terephthalate and the temperature is raised to 260° C. Antimony trioxide is added to carry out polymerization reaction for 5 hours to form dynamically crosslinked polyethylene terephthalate, wherein the molar number of the dynamic crosslinking agent is 0.6% of the molar number of the ethylene terephthalate.

[0028] Comparative Example 1

[0029] Dimethyl terephthalate and ethylene glycol were mixed in a mass ratio of 29:71, cadmium acetate and antimony trioxide were added, the temperature was raised to 200°C and reacted for 2 hours to synthesize ethylene terephthalate through ester exchange.

[0030] The PET fibers prepared from the PET polyester materials obtained in Examples 1-3 and Comparative Example 1 were subjected to mechanical property tests using the GBT 19975-2005 test method. The test results at room temperature are shown in the following table:

[0031]

[0032]

[0033] It can be seen from the above table that the creep resistance of the PET polyester materials of Examples 1-3 is significantly improved compared with that of Comparative Example 1. Dynamic bonds are used to generate dynamic crosslinking between straight polymer chains. When the service temperature of the material is much lower than the critical temperature of the dynamic bond exchange, the relaxation time of the dynamic crosslinking tends to infinity. The dynamic crosslinking is similar to permanent chemical crosslinking and can effectively limit the mutual slippage between polymer chains, significantly enhance the creep resistance of thermoplastic materials, and expand the application field of the materials.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high creep resistance PET polyester material, characterized in that: The steps include: (1) mixing dimethyl terephthalate and ethylene glycol, adding a catalyst, heating to 160-220° C. for reaction for 1-2 hours, and synthesizing ethylene terephthalate by transesterification; (2) mixing trimethylolpropane and pyromellitic anhydride and reacting them, and using the reaction product as a dynamic crosslinking agent for standby use; (3) The dynamic crosslinking agent is mixed with ethylene terephthalate and the temperature is raised to 240-300° C. A catalyst is added to carry out polymerization reaction for 3.5-5 hours to form dynamically crosslinked polyethylene terephthalate.

2. The method for preparing a highly creep-resistant PET polyester material according to claim 1, characterized in that: The catalyst in step (1) is cadmium acetate and antimony trioxide.

3. The method for preparing a highly creep-resistant PET polyester material according to claim 1, characterized in that: In the step (1), the mass ratio of dimethyl terephthalate to ethylene glycol is 23:77-35:

65.

4. The method for preparing a highly creep-resistant PET polyester material according to claim 1, characterized in that: In the step (2), the mass ratio of trimethylolpropane to pyromellitic anhydride is 35:65-55:

45.

5. The method for preparing a highly creep-resistant PET polyester material according to claim 1, characterized in that: The catalyst in step (3) is antimony trioxide.

6. The method for preparing a highly creep-resistant PET polyester material according to claim 1, characterized in that: The molar amount of the dynamic crosslinking agent in step (3) is 0.4%-0.7% of the molar amount of ethylene terephthalate.

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