Toughening type macromolecular antioxidant for polyamide and preparation method

Abstract

The invention discloses a toughening type macromolecular antioxidant for polyamide, which is characterized in that the structure of the antioxidant is as follows: # imgabs0 #, hindered phenol has impact resistance and oxidation resistance, has a better oxidation resistance effect after being added into the polyamide, and can increase the impact resistance of the polyamide at the same time.

Description

Technical Field

[0001] The 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 due to the effects of light, heat and oxygen, and their actual service life is significantly lower than their 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 transit 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, the service life is required to exceed 3000h at a temperature above 200℃), PA is extremely susceptible to the effects of heat and oxygen to cause crosslinking or chain breaking reactions, which degrades the mechanical properties and shortens the service life. 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 prone to migration or extraction and become ineffective. 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 migration of the antioxidant is reduced and the toughening effect of the antioxidant is achieved. However, the antioxidant effect still needs to be improved.

[0003] For certain specific usage requirements, such as areas prone to collision, higher requirements are placed on the impact resistance of polymers. For PA materials, additives that can achieve high-efficiency anti-oxidation and extend service life while achieving better impact toughness are still a problem that needs to be solved urgently. 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 agent in the prior art cannot take into account both high efficiency anti-oxidation 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 synthetic 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 drop excess thionyl chloride using a constant pressure dropper, and control the drop rate to be 1 drop / second; stir and react at 60° C. for 8 h to 16 h; after the reaction, remove unreacted thionyl chloride and solvent by rotary evaporation, and obtain a red liquid after cooling after the rotary evaporation is completed;

[0011] (2) Nitrogen is introduced into a flask, tetrahydrofuran is added to dissolve and placed in ice water (0°C-5°C), hexamethylenediamine is slowly added dropwise, stirred, and reacted for 1 hour. Anhydrous sodium carbonate is added and reacted for 12 hours to 24 hours. The product is obtained, the solvent is removed, and the product is poured into ice water. The precipitate is filtered and the filter cake is dried in a vacuum oven 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) propionamido)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 good 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 with different antioxidants added at 150℃ for different time of thermal oxidation aging;

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

[0022] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0023] Embodiment 1:

[0024] Add 13.3g of HPAP-COOH to a pear-shaped bottle, add 100mL of anhydrous tetrahydrofuran, stir at 60℃ for 5min, slowly add 12.3mL of thionyl chloride with a constant pressure dropper, and control the drop rate to be 1 drop / second; stir and react at 60℃ for 8.5h; after the reaction, evaporate to obtain a red liquid; pass nitrogen gas into the bottle for purging, add 100mL of anhydrous tetrahydrofuran to dissolve and place in ice water (0℃-5℃), add 3.48g of hexamethylenediamine, stir, react for 1h, add 6.36g of anhydrous sodium carbonate, and react for 24h. After the reaction is completed, spin dry, add ice water, ultrasonically wash and filter to obtain a yellow powder, and vacuum dry at 60℃ to obtain the antioxidant Macro-HPAP.

[0025] Embodiment 2:

[0026] Add 13.3g of HPAP-COOH to a pear-shaped bottle, add 100mL of anhydrous tetrahydrofuran, stir at 60℃ for 5min, slowly add 8.8mL of thionyl chloride with a constant pressure dropper, and control the drop rate to 1 drop / second; stir and react at 60℃ for 15h; after the reaction, evaporate to obtain a red liquid; pass nitrogen gas into the bottle for purging, add 100mL of anhydrous tetrahydrofuran to dissolve and place in ice water (0℃-5℃), add 3.48g of hexamethylenediamine, stir, react for 1h, add 6.36g of anhydrous sodium carbonate, and react for 16h. After the reaction is completed, spin dry, add ice water, ultrasonically wash and filter to obtain a yellow powder, and vacuum dry at 60℃ 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 and 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 on the 8th day after aging is still 93%, while the tensile strength retention rate of PA6 / 1010 on the 3rd day after aging is only 77%, and the tensile strength retention rate of pure PA6 on the 2nd day after aging is only 53%. 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, Features: The antioxidant structure is as follows:

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

3. The method for preparing the toughening macromolecular antioxidant for polyamide according to claim 2, Features: The reaction steps are as follows: take 5-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamido)isophthalic acid (HPAP-COOH) and tetrahydrofuran, add thionyl chloride to carry out chlorination reaction, and stir at 60°C for 8h-16h; after the reaction, obtain the chlorination product; then introduce nitrogen, add tetrahydrofuran to dissolve and place in 0°C-5°C ice water, slowly add hexamethylenediamine dropwise, add anhydrous sodium carbonate after reacting for 1h, continue to react for 12h-24h, remove the solvent to obtain the product, pour into ice water, precipitate and filter, and vacuum dry the filter cake.

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

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