Hydrolysis-resistant polyester elastomer and method for producing the same

Abstract

The application discloses a kind of hydrolysis-resistant polyester elastomer and preparation method thereof, belong to polyester elastomer technical field.The technical scheme is as follows: including the following weight parts of component: 100 parts of terephthalic acid, 1-20 parts of 2,6-naphthalene dicarboxylic acid, 5-10 parts of carboxyl-terminated hyperbranched polysiloxane, 50-200 parts of aliphatic dihydric alcohol, 50-500 parts of polyether dihydric alcohol, 0.01-2 parts of catalyst, 0.1-5 parts of antioxidant.The application can improve the hydrolysis resistance of polyester elastomer while not compromising its tensile strength by introducing 2,6-naphthalene dicarboxylic acid and carboxyl-terminated hyperbranched polysiloxane, and can widen the application field of polyester elastomer.

Description

Technical Field

[0001] This invention relates to the field of polyester elastomer technology, and specifically to a hydrolysis-resistant polyester elastomer and its preparation method. Background Technology

[0002] Thermoplastic polyester elastomer, also known as TPEE, is mainly composed of polybutylene terephthalate (PBT) with high crystallinity and a high melting point as the hard segment (crystalline phase), and polyether or polyester with a lower glass transition temperature as the soft segment (amorphous phase). TPEE exhibits the high elasticity of vulcanized rubber at room temperature, while at high temperatures it is as easy to process and mold as thermoplastics, combining the characteristics of both vulcanized rubber and thermoplastics.

[0003] Research on TPEE began around 1950. Due to its high comprehensive mechanical properties, excellent heat resistance, outstanding chemical resistance and weather resistance, it is now widely used in automobiles, electronics, industrial products, sporting goods, films, medical devices, and co-alloys.

[0004] Because thermoplastic polyester elastomers generally have poor hydrolysis resistance, especially in humid heat, their mechanical properties deteriorate after prolonged exposure to humid and hot environments, limiting their application in such conditions. Currently, the short-term or long-term hydrolysis resistance of polyester elastomers is mainly achieved through carbodiimide compounds. The main mechanism is that carbodiimides readily react with carboxylic acids to form stable acylureas, inhibiting further hydrolysis. For example, Chinese invention patents CN103897356B and CN105482388B significantly improved the long-term hydrolysis resistance of polymers by adding polycarbodiimide compounds; after immersion in 95°C hot water for 90 days, their tensile strength and elongation at break remained excellent. However, carbodiimide compounds reduce the stability of aqueous dispersion systems and increase melt viscosity, which is detrimental to injection molding.

[0005] Polysiloxanes possess excellent high and low temperature resistance and hydrolysis resistance, and when mixed with polyester elastomers, they improve the hydrolysis resistance of polyester elastomers. However, simply physically blending polysiloxanes with polyester elastomers leads to poor compatibility, microphase separation, and a decline in product performance. Therefore, from a molecular structure design perspective, polysiloxanes should be grafted into polyester elastomer segments to improve the hydrolysis resistance of polyester elastomers.

[0006] Chinese invention patent CN102115533B discloses a polyester elastomer with mixed soft segments and low temperature resistance, and its preparation method. The polyester elastomer mainly contains dimethyl aromatic dicarboxylate (or aromatic dicarboxylic acid). a,oh-Aliphatic glycols, polyether glycols, hydroxyl-terminated polydimethylsiloxanes, and mixed soft segments composed of polyethylene glycol, polypropylene glycol, and polytetrahydrofuran ether glycol have the advantages of better elasticity and low-temperature resistance, but hydrolysis resistance is not mentioned. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a hydrolysis-resistant polyester elastomer and its preparation method. By introducing 2,6-naphthalenedicarboxylic acid and carboxyl-terminated hyperbranched polysiloxane, the hydrolysis resistance of the polyester elastomer can be improved without damaging its tensile strength, and its resistance to damp heat is excellent, which can broaden the application field of polyester elastomer.

[0008] The technical solution of this invention is as follows: On one hand, the present invention provides a hydrolysis-resistant polyester elastomer comprising the following components in parts by weight: 100 parts of terephthalic acid 1-20 parts of 2,6-naphthalenedicarboxylic acid 5-10 parts of carboxyl-terminated hyperbranched polysiloxane 50-200 parts aliphatic diols 50-500 parts of polyether diol Catalyst 0.01-2 parts Antioxidant 0.1-5 parts.

[0009] Preferably, the aliphatic diol is one or more selected from ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, diethylene glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanediethanol.

[0010] Preferably, the polyether diol is one or more of polyethylene glycol, polypropylene glycol, and polytetramethylene ether diol.

[0011] Preferably, the number average molecular weight of the polyether diol is 500-5000.

[0012] Preferably, the catalyst is one or more of zinc acetate, magnesium acetate, calcium acetate, titanium dioxide, germanium dioxide, antimony trioxide, antimony acetate, antimony glycolate, antimony polyethylene glycol, triisobutylaluminum, dibutyltin oxide, stannous octoate, monobutyltriisooctanoate, dioctyltin oxide, tetrabutyl titanate, and isopropyl titanate.

[0013] Preferably, the antioxidant is one or more of antioxidant 1010, antioxidant 1098, antioxidant 168, antioxidant 1076, antioxidant 330 and antioxidant 1330.

[0014] Preferably, the ratio of the amount of the aliphatic diol to the sum of the amounts of terephthalic acid and 2,6-naphthalenedicarboxylic acid is 1.2-2.0:1.

[0015] On the other hand, the present invention provides a method for preparing the above-mentioned hydrolysis-resistant polyester elastomer, comprising the following steps: S1 involves adding terephthalic acid, 2,6-naphthalenedicarboxylic acid, carboxyl-terminated hyperbranched polysiloxane, aliphatic diol, polyether diol, catalyst, and antioxidant into a polymerization reactor for esterification reaction at a temperature of 180-240℃ for 30-120 minutes. After the esterification reaction is completed, the temperature of the polymerization reactor is raised to 220-240℃ and polymerization is carried out under a low vacuum of more than 1000 Pa for 30-60 minutes. Then the temperature is raised to 240-280℃ and polymerization is carried out under a high vacuum of less than 100 Pa for 60-180 minutes to obtain polyester elastomer.

[0016] Preferably, the method for preparing the carboxyl-terminated hyperbranched polysiloxane is as follows: adipic acid and triethoxysilane are mixed in a molar ratio of 2:1 and heated at 80-120°C under a N2 atmosphere until the system becomes clear and transparent. Then, the temperature is raised to 120-150°C until distillate is produced. The reaction stops when no distillate is produced and the temperature is lowered to room temperature to obtain the carboxyl-terminated hyperbranched polysiloxane.

[0017] Preferably, the triethoxysilane is one or more of 3-epoxypropoxypropyltriethoxysilane, 3-aminopropyltriethoxysilane, and vinyltriethoxysilane.

[0018] Compared with the prior art, the present invention has the following advantages: 1. In the synthesis of polyester elastomers, the present invention introduces carboxyl-terminated hyperbranched polysiloxanes. Due to the hydrophobicity of carboxyl-terminated hyperbranched polysiloxanes, the hydrolysis resistance of polyester elastomers is enhanced. However, the addition of carboxyl-terminated hyperbranched polysiloxanes alone will reduce the tensile strength of polyester elastomers. Therefore, the present invention introduces 2,6-naphthalenedicarboxylic acid, which not only increases the strength of polyester elastomers but also further improves their hydrolysis resistance.

[0019] 2. This invention can improve the hydrolysis resistance, especially the resistance to damp heat, of thermoplastic polyester elastomers, maintaining good tensile strength even under long-term damp heat conditions. After immersing the polyester elastomer of this invention in hot water at 95°C for 90 days, its tensile strength retention rate can still reach over 85%. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0021] Unless otherwise specified, all chemical reagents and chemicals mentioned in the embodiments of this invention are well-known and commonly used chemical reagents and chemicals in the prior art. Experimental methods in the embodiments of this invention that do not specify specific conditions should be performed according to conventional methods and conditions or according to the product instructions.

[0022] The performance testing method in this embodiment of the invention is as follows: Tensile strength: Tested according to standard GB / T 1040.2-2022, using a test speed of 50 mm / min.

[0023] Hydrolysis resistance test: The sample is immersed in hot water at 95°C for 90 days. During this period, the sample is removed, allowed to cool, and its tensile strength is tested.

[0024] Example 1 The preparation method of carboxyl-terminated hyperbranched polysiloxane in this embodiment is as follows: adipic acid and vinyltriethoxysilane are mixed in a molar ratio of 2:1 and heated at 120°C under a N2 atmosphere until the system becomes clear and transparent. Then the temperature is raised to 150°C and distillate begins to be produced. The reaction stops when no distillate is produced and the temperature is lowered to room temperature to obtain carboxyl-terminated hyperbranched polysiloxane.

[0025] The method for preparing the hydrolysis-resistant polyester elastomer in this embodiment includes the following steps: S1 contains 1 kg of terephthalic acid, 0.1 kg of 2,6-naphthalenedicarboxylic acid, 0.05 kg of carboxyl-terminated hyperbranched polysiloxane, 0.9 kg of 1,4-butanediol, and polytetramethylene ether diol (M n =1000) 1kg, tetrabutyl titanate 1g, magnesium acetate 1g, antioxidant 10105g and antioxidant 168 5g are added to the reaction vessel, and the temperature is raised to 180℃ under nitrogen protection to carry out the esterification reaction for 1h. After the esterification reaction is completed, the temperature of the reactor is raised to 240°C and polymerized under a low vacuum of over 1000 Pa for 30 minutes. Then the temperature is raised to 260°C and polymerized under a high vacuum of under 100 Pa for 2 hours to obtain the polyester elastomer.

[0026] Example 2 The preparation method of carboxyl-terminated hyperbranched polysiloxane in this embodiment is as follows: adipic acid and 3-epoxypropoxypropyltriethoxysilane are mixed in a molar ratio of 2:1 and heated at 80°C under a N2 atmosphere until the system becomes clear and transparent. Then the temperature is raised to 140°C and distillate is produced. The reaction stops when no distillate is produced and the temperature is lowered to room temperature to obtain carboxyl-terminated hyperbranched polysiloxane.

[0027] The method for preparing the hydrolysis-resistant polyester elastomer in this embodiment includes the following steps: S1 contains 1 kg of terephthalic acid, 0.2 kg of 2,6-naphthalenedicarboxylic acid, 0.1 kg of carboxyl-terminated hyperbranched polysiloxane, 0.8 kg of 1,4-butanediol, 0.2 kg of neopentyl glycol, and polytetramethylene ether diol (M... n =2000) 0.8kg, ethylene glycol antimony 1.5g, and antioxidant 1098 8g were added to the reactor. Under nitrogen protection, the temperature was raised to 220℃ to carry out the esterification reaction for 1 hour. After the esterification reaction is completed, the polymerization temperature is raised to 230°C and polymerized under a low vacuum of over 1000 Pa for 30 minutes. Then the temperature is raised to 250°C and polymerized under a high vacuum of under 100 Pa for 2 hours to obtain the polyester elastomer.

[0028] Example 3 The preparation method of carboxyl-terminated hyperbranched polysiloxane in this embodiment is as follows: adipic acid and 3-aminopropyltriethoxysilane are mixed in a molar ratio of 2:1 and heated at 100°C under a N2 atmosphere until the system becomes clear and transparent. Then the temperature is raised to 150°C and distillate is produced. The reaction stops when no distillate is produced and the temperature is lowered to room temperature to obtain carboxyl-terminated hyperbranched polysiloxane.

[0029] The method for preparing the hydrolysis-resistant polyester elastomer in this embodiment includes the following steps: S1 adds 1 kg of terephthalic acid, 0.15 kg of 2,6-naphthalenedicarboxylic acid, 0.1 kg of carboxyl-terminated hyperbranched polysiloxane, 0.9 kg of 1,4-butanediol, 0.2 kg of ethylene glycol, 1 kg of polytetramethylene ether diol (Mn=1000), 0.2 kg of polypropylene glycol (Mn=1000), 0.5 g of antimony trioxide, 0.8 g of tetrabutyl titanate, 5 g of antioxidant 1010, and 5 g of antioxidant 168 to a reaction vessel. Under nitrogen protection, the temperature is raised to 230℃ for esterification reaction, and the reaction time is 0.5 h. After the esterification reaction is completed, the polymerization temperature is raised to 240°C and polymerized under a low vacuum of over 1000 Pa for 30 minutes. Then the temperature is raised to 250°C and polymerized under a high vacuum of under 100 Pa for 2 hours to obtain the polyester elastomer.

[0030] Example 4 The preparation method of carboxyl-terminated hyperbranched polysiloxane in this embodiment is as follows: adipic acid and vinyltriethoxysilane are mixed in a molar ratio of 2:1 and heated at 120°C under a N2 atmosphere until the system becomes clear and transparent. Then the temperature is raised to 140°C and distillate is produced. The reaction stops when no distillate is produced and the temperature is lowered to room temperature to obtain carboxyl-terminated hyperbranched polysiloxane.

[0031] The method for preparing the hydrolysis-resistant polyester elastomer in this embodiment includes the following steps: S1 contains 1 kg of terephthalic acid, 0.2 kg of 2,6-naphthalenedicarboxylic acid, 0.05 kg of carboxyl-terminated hyperbranched polysiloxane, 0.8 kg of 1,4-butanediol, and polytetramethylene ether diol (M... n =1000) 1.8kg, tetrabutyl titanate 3g, magnesium acetate 2g, antioxidant 1098 8g are added to the reaction vessel, and the temperature is raised to 210℃ under nitrogen protection to carry out the esterification reaction for 1h; After the esterification reaction is completed, the polymerization temperature is raised to 235°C and polymerized under a low vacuum of over 1000 Pa for 30 minutes. Then the temperature is raised to 245°C and polymerized under a high vacuum of under 100 Pa for 2 hours to obtain the polyester elastomer.

[0032] Comparative Example 1 The difference from Example 1 is that 2,6-naphthalenedicarboxylic acid is not added.

[0033] Comparative Example 2 The difference from Example 1 is that the amount of 2,6-naphthalenedicarboxylic acid added is 0.3 kg.

[0034] Comparative Example 3 The difference from Example 1 is that no carboxyl-terminated hyperbranched polysiloxane is added.

[0035] Comparative Example 4 The difference from Example 1 is that the amount of carboxyl-terminated hyperbranched polysiloxane added is 0.3 kg.

[0036] Comparative Example 5 The difference from Example 1 is that the carboxyl-terminated hyperbranched polysiloxane is replaced with hydroxyl-terminated polydimethylsiloxane.

[0037] Comparative Example 6 The difference from Example 1 is that 2,6-naphthalenedicarboxylic acid and carboxyl-terminated hyperbranched polysiloxane are not added.

[0038] The polyester elastomers prepared in Examples 1-4 and Comparative Examples 1-6 were subjected to performance tests, and the test results are shown in Table 1.

[0039] Table 1. Test results of polyester elastomers in Examples 1-4 and Comparative Examples 1-6 As shown in Table 1, the initial tensile strength of the polyester elastomer prepared in the embodiments of the present invention is 30-40 MPa. After the polyester elastomer is immersed in hot water at 95°C for 90 days, its tensile strength is 26-36 MPa, and the retention rate is above 85%.

[0040] By comparing Comparative Examples 1-3 and Comparative Example 6, it can be found that the addition of 2,6-naphthalenedicarboxylic acid can increase the initial tensile strength of polyester elastomers, but its improvement on hydrolysis resistance is relatively weak. Comparative Example 6, which does not contain 2,6-naphthalenedicarboxylic acid and carboxyl-terminated hyperbranched polysiloxane, has a tensile strength retention rate of 38%, while Comparative Example 3, which contains 2,6-naphthalenedicarboxylic acid, has a tensile strength retention rate of 54%. Similarly, if the amount of 2,6-naphthalenedicarboxylic acid added is increased from 0.1 kg to 0.3 kg, the tensile strength retention rate of the polyester elastomer only increases from 54% (Comparative Example 3) to 65% (Comparative Example 2). Considering that 2,6-naphthalenedicarboxylic acid requires a complex purification and preparation process, its content can be controlled within a certain range to meet application requirements.

[0041] By comparing Comparative Examples 1, 3-4 and Comparative Example 6, it can be found that adding carboxyl-terminated hyperbranched polysiloxane can increase the hydrolysis resistance of polyester elastomers, and the tensile strength retention rate increases from 38% in Comparative Example 6 to 75% in Comparative Example 1; however, when the content of carboxyl-terminated hyperbranched polysiloxane is too high, the initial tensile strength decreases from 32 MPa in Comparative Example 1 to 25 MPa in Comparative Example 4.

[0042] By comparing Example 1, Comparative Examples 1 and 3, it can be found that the tensile strength retention rate of Example 1 is 89%, while the retention rate of 2,6-naphthalenedicarboxylic acid alone is 54% (Comparative Example 3), and the retention rate of carboxyl-terminated hyperbranched polysiloxane alone is 75% (Comparative Example 1). Therefore, it can be concluded that the polyester elastomer exhibits superior tensile strength retention when both 2,6-naphthalenedicarboxylic acid and carboxyl-terminated hyperbranched polysiloxane are added simultaneously, indicating a certain degree of synergy between the two.

[0043] By comparing Example 1 and Comparative Example 5, it can be found that the tensile strength retention rate of the polyester elastomer with added carboxyl-terminated hyperbranched polysiloxane is better than that of the polyester elastomer with added hydroxyl-terminated polydimethylsiloxane, with tensile strength retention rates of 89% and 77%, respectively. This is because the branched structure provides stronger hydrophobicity to the polyester elastomer.

[0044] In summary, by introducing 2,6-naphthalenedicarboxylic acid and carboxyl-terminated hyperbranched polysiloxane into polyester elastomers, hydrolysis resistance can be improved without compromising their initial tensile strength, and the two substances exhibit synergistic effects.

Claims

1. Hydrolysis-resistant polyester elastomer, characterized in that, The components include the following parts by weight: 100 parts of terephthalic acid 1-20 parts of 2,6-naphthalenedicarboxylic acid 5-10 parts of carboxyl-terminated hyperbranched polysiloxane 50-200 parts aliphatic diols 50-500 parts of polyether diol Catalyst 0.01-2 parts Antioxidant 0.1-5 parts; The method for preparing the carboxyl-terminated hyperbranched polysiloxane is as follows: adipic acid and triethoxysilane are mixed in a molar ratio of 2:1 and heated at 80-120°C under a N2 atmosphere until the system becomes clear and transparent. Then, the temperature is raised to 120-150°C and distillate begins to be produced. The reaction stops when no distillate is produced and the temperature is lowered to room temperature to obtain the carboxyl-terminated hyperbranched polysiloxane.

2. The hydrolysis resistant polyester elastomer of claim 1, wherein, The aliphatic diol is one or more selected from ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, neopentyl glycol, diethylene glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanediethanol.

3. The hydrolysis resistant polyester elastomer of claim 1, wherein, The polyether diol is one or more of polyethylene glycol, polypropylene glycol, and polytetramethylene ether diol.

4. The hydrolysis resistant polyester elastomer of Claim 1 wherein, The number average molecular weight of the polyether diol is 500-5000.

5. The hydrolysis resistant polyester elastomer of claim 1 wherein, The catalyst is one or more of the following: zinc acetate, magnesium acetate, calcium acetate, titanium dioxide, germanium dioxide, antimony trioxide, antimony acetate, antimony glycol, antimony polyethylene glycol, triisobutylaluminum, dibutyltin oxide, stannous octoate, monobutyltriisooctanoate, dioctyltin oxide, tetrabutyl titanate, and isopropyl titanate.

6. The hydrolysis resistant polyester elastomer of Claim 1 wherein, The antioxidant is one or more of antioxidant 1010, antioxidant 1098, antioxidant 168, antioxidant 1076, antioxidant 330 and antioxidant 1330.

7. The hydrolysis-resistant polyester elastomer as described in claim 1, characterized in that, The ratio of the amount of the aliphatic diol to the sum of the amounts of terephthalic acid and 2,6-naphthalenedicarboxylic acid is 1.2-2:

1.

8. The hydrolysis-resistant polyester elastomer as described in claim 1, characterized in that, The triethoxysilane is one or more of 3-epoxypropoxypropyltriethoxysilane, 3-aminopropyltriethoxysilane, and vinyltriethoxysilane.

9. The method for preparing the hydrolysis-resistant polyester elastomer according to any one of claims 1-7, characterized in that, Includes the following steps: S1 involves adding terephthalic acid, 2,6-naphthalenedicarboxylic acid, carboxyl-terminated hyperbranched polysiloxane, aliphatic diol, polyether diol, catalyst, and antioxidant into a polymerization reactor for esterification reaction at a temperature of 180-240℃ for 30-120 minutes. After the esterification reaction is completed, the temperature of the polymerization reactor is raised to 220-240℃ and polymerization is carried out under a low vacuum of more than 1000 Pa for 30-60 minutes. Then the temperature is raised to 240-280℃ and polymerization is carried out under a high vacuum of less than 100 Pa for 60-180 minutes to obtain polyester elastomer.

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