A toughening macromolecular antioxidant for polyamide and preparation method thereof

Abstract

The invention discloses a toughening macromolecular antioxidant for polyamide, which is characterized in that the antioxidant structure is as follows: the hindered phenol has both impact resistance and antioxidant properties, has good antioxidant effect when added to polyamide, and can also increase the impact resistance of the polyamide.

Description

Technical Field

[0001] The present invention relates to the field of polymer antioxidants, in particular to a method for preparing an auxiliary agent for polyamide with the dual functions of toughening and anti-oxidation. Background Art

[0002] During processing and use, polymers are susceptible to aging caused by light, heat and oxygen, and their actual service life is significantly lower than the theoretical life. Polyamide, also known as nylon (PA), has a high heat deformation temperature and good mechanical properties, and is widely used in 5G electronic devices, rail transportation and automotive fields. When serving in a high temperature environment for a long time (such as the normal operating temperature of high-frequency power equipment is as high as 150℃-200℃, such as automobile engine parts, at a temperature above 200℃, the service life is required to exceed 3000h), PA is extremely susceptible to the effects of heat and oxygen to cause crosslinking or chain breaking reactions, mechanical properties deteriorate, and service life is shortened. The oxidation rate of PA is faster than that of polyolefins, so there is no oxidation induction time for the oxidation of PA. In order to inhibit the crosslinking / breaking of the molecular chains of PA materials during service, the most direct and effective way to extend the service life is to add antioxidants. Hindered phenol antioxidants are commonly used polymer main antioxidants. Commonly used hindered phenol antioxidants for PA are 1010 (see attached for structure Figure 1 However, commercial antioxidants are susceptible to migration or extraction, leading to their ineffectiveness. He Min's team synthesized a small-molecule antioxidant containing double bonds and copolymerized it with N-phenylmaleimide and styrene to form a macromolecular antioxidant (CN 117186302A). By increasing the molecular weight, the antioxidant's mobility was reduced and its toughening effect was achieved. However, the antioxidant effect still needs to be improved.

[0003] For certain specific usage requirements, such as areas prone to impact, there are high requirements for the impact resistance of polymers. For PA materials, the development of additives that can achieve high-efficiency anti-oxidation and extend service life while achieving good impact toughness remains an urgent problem to be solved. Summary of the Invention

[0004] The purpose of the present invention is to provide a toughening macromolecular antioxidant for polyamide and a preparation method thereof, so as to solve the technical problem that the auxiliary agents in the prior art cannot achieve both high efficiency antioxidant and extended service life and good impact toughness.

[0005] The technical solution of the present invention is a toughening macromolecular antioxidant for polyamide, the structure of the antioxidant is as follows:

[0006]

[0007] The synthesis reaction formula of the antioxidant is as follows:

[0008]

[0009] The preparation method of the antioxidant Macro-HPAP comprises the following reaction:

[0010] (1) Add 5-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamido)isophthalic acid (HPAP-COOH) and tetrahydrofuran to a single-necked flask, heat to dissolve, slowly add excess thionyl chloride dropwise using a constant pressure dropper, and control the drop rate to be 1 drop / second; stir and react at 60°C for 8h-16h; after the reaction, remove the unreacted thionyl chloride and solvent by rotary evaporation, and cool after the rotary evaporation is completed to obtain a red liquid;

[0011] (2) Nitrogen was introduced into the flask, tetrahydrofuran was added to dissolve the mixture and placed in ice water (0°C-5°C), hexamethylenediamine was slowly added dropwise, stirred, and reacted for 1 hour. Anhydrous sodium carbonate was added and reacted for 12 hours to 24 hours to obtain the product. The solvent was removed and poured into ice water. The precipitate was filtered and the filter cake was vacuum dried at 60°C.

[0012] The dichloromethane and tetrahydrofuran used in the reaction in the preparation method are anhydrous solvents or have been treated to remove water;

[0013] In the preparation method, the ratio of HPAP-COOH to thionyl chloride is 1:2-1:6, preferably 1:4;

[0014] In the preparation method, the ratio of HPAP-COOH to hexamethylenediamine is 1:1.

[0015] Beneficial effects of the present invention: The present invention prepares a macromolecular antioxidant, which has a good antioxidant effect when added to polyamide, and can also increase the impact resistance of polyamide. Specifically: an additive for polyamide with both impact resistance and antioxidant properties is prepared by polycondensation of 5-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide)isophthalic acid (HPAP-COOH) and hexamethylenediamine. The tensile strength retention rate of PA6 / Macro-HPAP still reaches 93% on the 8th day after aging, while the tensile strength retention rate of PA6 / 1010 on the 3rd day of aging is only 77%, and the tensile strength retention rate of pure PA6 on the 2nd day of aging is only 53%. This shows that Macro-HPAP has a better antioxidant effect, can better inhibit PA aging, and maintain mechanical properties. The impact strengths of PA6, PA6 / 1010, and PA6 / Macro-HPAP are 8.5, 9.5, and 14 kJ / m, respectively. 2 In summary, Macro-HPAP has both good antioxidant properties and good toughening effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The structure of antioxidant 1010;

[0017] Figure 2Macro-HPAP 1 H NMR;

[0018] Figure 3 Macro-HPAP 13 C NMR;

[0019] Figure 4 Molecular weight and distribution of Macro-HPAP;

[0020] Figure 5 The tensile strength of PA6 after adding different antioxidants to it at 150℃ and aging for different times;

[0021] Figure 6 Tensile impact strength diagram of PA6 with different antioxidants added. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings and examples, but they are not intended to limit the present invention.

[0023] Example 1:

[0024] To a pear-shaped flask, add 13.3 g of HPAP-COOH and 100 mL of anhydrous tetrahydrofuran. Stir at 60°C for 5 minutes. Slowly add 12.3 mL of thionyl chloride using a constant pressure dropper at a rate of 1 drop / second. Stir and react at 60°C for 8.5 hours. After the reaction, rotary evaporation yields a red liquid. Purge the flask with nitrogen, add 100 mL of anhydrous tetrahydrofuran, dissolve the mixture, and place in ice water (0-5°C). Add 3.48 g of hexamethylenediamine, stir, and react for 1 hour. Then, add 6.36 g of anhydrous sodium carbonate and react for 24 hours. After the reaction, spin dry, add ice water, ultrasonically wash, and filter to obtain a yellow powder, which is then dried under vacuum at 60°C to obtain the antioxidant Macro-HPAP.

[0025] Example 2:

[0026] To a pear-shaped flask, add 13.3 g of HPAP-COOH and 100 mL of anhydrous tetrahydrofuran. Stir at 60°C for 5 minutes. Slowly add 8.8 mL of thionyl chloride using a constant pressure dropper at a rate of 1 drop / second. Stir and react at 60°C for 15 hours. After the reaction, rotary evaporation yields a red liquid. Purge the flask with nitrogen, add 100 mL of anhydrous tetrahydrofuran, dissolve the mixture, and place in ice water (0-5°C). Add 3.48 g of hexamethylenediamine, stir, and react for 1 hour. Then, add 6.36 g of anhydrous sodium carbonate and react for 16 hours. After the reaction, spin dry, add ice water, ultrasonically wash, and filter to obtain a yellow powder, which is then vacuum-dried at 60°C to obtain the antioxidant Macro-HPAP.

[0027] Application Examples

[0028] 10g antioxidant Macro-HPAP, 1010 was added to 1kg PA6, and standard 1A type specimens were made by extrusion injection molding. The specimens were placed at 150℃ for aging for 0-12 days, and the mechanical properties of the specimens were tested. The results are shown in the attached Figure 5-6 The tensile strength retention rate of PA6 / Macro-HPAP still reached 93% on the 8th day after aging, while the tensile strength retention rate of PA6 / 1010 was only 77% on the 3rd day after aging, and the tensile strength retention rate of pure PA6 was only 53% on the 2nd day after aging. This shows that Macro-HPAP has a better antioxidant effect, which can better inhibit PA aging and maintain mechanical properties. The impact strengths of PA6, PA6 / 1010, and PA6 / Macro-HPAP are 8.5, 9.5, and 14 kJ / m, respectively. 2 In summary, Macro-HPAP has both good antioxidant properties and good toughening effect.

Claims

1. A toughening macromolecular antioxidant for polyamide, characterized in that: The antioxidant structure is as follows:

2. The method for preparing the toughening macromolecular antioxidant for polyamide according to claim 1, wherein: The reaction formula is as follows:

3. The method for preparing the toughening macromolecular antioxidant for polyamide according to claim 2, characterized in that: The reaction steps are as follows: taking 5-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamido)isophthalic acid (HPAP-COOH) and tetrahydrofuran, adding thionyl chloride to carry out chlorination reaction, stirring and reacting at 60°C for 8h-16h; obtaining chlorination product after reaction; then introducing nitrogen, adding tetrahydrofuran to dissolve and placing in 0°C-5°C ice water, slowly adding hexamethylenediamine dropwise, reacting for 1h, adding anhydrous sodium carbonate, continuing the reaction for 12h-24h, removing the solvent to obtain the product, pouring into ice water, filtering the precipitate, and vacuum drying the filter cake.

4. The method for preparing the toughening macromolecular antioxidant for polyamide according to claim 3, characterized in that: The ratio of HPAP-COOH to thionyl chloride is 1:2-1:

6.

5. The method for preparing the toughening macromolecular antioxidant for polyamide according to claim 3, characterized in that: The ratio of HPAP-COOH to hexamethylenediamine is 1:

1.

6. The method for preparing the toughening macromolecular antioxidant for polyamide according to claim 4, characterized in that: The ratio of HPAP-COOH to thionyl chloride is 1:4.

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