High-strength pa6 composite material and preparation method therefor

Abstract

A high-strength PA6 composite material and a preparation method therefor, the PA6 composite material comprising, in parts by mass, 80-95 parts of caprolactam, 1-3 parts of benzoic acid and 10-30 parts of a modification additive. The benzoic acid is used for improving the tensile strength of the composite material, and the modification additive is used for enhancing the impact resistance of the composite material. Terephthalic acid and m-xylylenediamine undergo a reaction to generate m-xylylenediamine terephthalate, which is then subjected to a polycondensation reaction with caprolactam, so as to introduce same into the backbone of a PA6 molecule and modify the PA6 resin. The modified PA6 resin has remarkably improved tensile strength and impact resistance, so that the application range of the PA6 composite material can be greatly expanded.

Description

High-strength PA6 composite material and preparation method Technical Field

[0001] The present invention relates to the field of PA6 composite materials, and in particular to a high-strength PA6 composite material and a preparation method thereof. Background Art

[0002] Nylon 6, also known as PA6, polyamide 6, and nylon 6, is a polymer compound. Nylon 6 has a low melting point and a wide processing temperature range. While it offers better impact resistance and solvent resistance than nylon 66 plastic, it also has a higher hygroscopicity profile. Because many quality properties of plastic parts are affected by hygroscopicity, this must be fully considered when designing products using nylon 6. Various modifiers are often added to enhance the mechanical properties of nylon 6.

[0003] For products without additives, the shrinkage of nylon 6 plastic raw materials is between 1% and 1.5%. The addition of glass fiber additives can reduce the shrinkage to 0.3% (but it is slightly higher in the direction perpendicular to the process). The shrinkage of molding assembly is mainly affected by the crystallinity and hygroscopicity of the material. The actual shrinkage is also a function of the plastic part design, wall thickness and other process parameters. Nylon 6 injection molding drying treatment Since nylon 6 easily absorbs moisture, special attention should be paid to drying before processing. If the material is supplied in waterproof material packaging, the container should be kept airtight. If the humidity is greater than 0.2%, it is recommended to dry it in hot air above 80°C for 16 hours. If the material has been exposed to air for more than 8 hours, it is recommended to vacuum dry it at 105°C for more than 8 hours.

[0004] Currently, nylon 6 has low toughness and low impact resistance, which greatly limits the application of nylon 6. Therefore, it is urgent to prepare a nylon 6 composite material with strong impact resistance to expand the application range of nylon 6.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to provide a high-strength PA6 composite material and a preparation method thereof, so as to improve the impact strength of the PA6 composite material and expand the application range of the PA6 composite material.

[0007] To solve the above technical problems, the present invention provides a high-strength PA6 composite material, which comprises, by weight: 80 to 95 parts of caprolactam; 1 to 3 parts of benzoic acid; 10 to 30 parts of a modifying agent;

[0008] The benzoic acid is used to improve the tensile strength of the composite material, and the modification aid is used to enhance the impact resistance of the composite material.

[0009] Furthermore, the modifying agent includes terephthalic acid and m-xylylenediamine, and the terephthalic acid and m-xylylenediamine react to generate m-xylylenediamine terephthalate salt reinforcing agent.

[0010] Furthermore, the ratio of the terephthalic acid to the m-xylylenediamine is 1:1.

[0011] Furthermore, it also includes an antioxidant, the weight portion of the antioxidant is 2 to 4 parts, and the antioxidant is used to resist the oxidative decomposition and aging of the PA6 composite material in a high temperature and high oxygen environment.

[0012] Furthermore, the antioxidant is compounded by antioxidant 1010 and antioxidant 168.

[0013] Furthermore, the compounding ratio of the antioxidant 1010 to the antioxidant 168 is 1:(1-2).

[0014] The present invention also discloses a method for preparing a high-strength PA6 composite material, comprising:

[0015] Weighing appropriate amounts of terephthalic acid and m-xylenediamine according to a ratio to prepare m-xylenediamine terephthalate;

[0016] Weigh appropriate amounts of caprolactam and m-phenylenediamine terephthalate according to the ratio and put them into the reactor, and then add benzoic acid and antioxidant to react;

[0017] Use high-purity nitrogen to replace the air in the reactor 3 to 4 times, raise the temperature to 200°C to 240°C, and maintain the pressure in the reactor at 1.2 to 1.5 MPa. Keep the temperature and pressure for 1.5 to 2.5 hours;

[0018] The temperature was raised to 240°C to 260°C, the pressure in the reactor was maintained at 1.5MPa to 2.0MPa, and after maintaining the pressure for 1.2h to 1.8h, the air was released to 0.05 to 0.15MPa, and the water vapor was exhausted and vacuumed to reduce the pressure in the reactor to -0.06MPa to -0.08MPa. After maintaining the pressure for 0.8h to 1.2h, the PA6 composite resin was obtained.

[0019] Furthermore, the preparation method of the m-phenylenediamine terephthalate salt comprises:

[0020] Add a certain amount of m-phenylenediamine to deionized water, stir and disperse, and heat to a first temperature to dissolve;

[0021] adding a terephthalic acid solution and maintaining the temperature at the second temperature until the pH reaches 7 to 8 to obtain a m-xylylenediamine terephthalate salt solution;

[0022] The m-xylylenediamine terephthalate salt solution is placed at a sub-zero temperature and filtered to obtain the m-xylylenediamine terephthalate salt containing a certain amount of water;

[0023] The m-xylylenediamine terephthalate salt containing a certain amount of water is placed in an environment with a temperature of 45° C. to 55° C. and an absolute pressure of 900 Pa to 1100 Pa and dried for 5 to 6 hours to obtain the m-xylylenediamine terephthalate salt.

[0024] Furthermore, the first temperature is lower than the second temperature.

[0025] Furthermore, the first temperature is 45°C to 50°C, and the second temperature is 50°C to 80°C.

[0026] Compared with the prior art, the present invention has at least the following beneficial effects:

[0027] The present invention generates m-xylylenediamine terephthalate by reacting terephthalic acid with m-xylylenediamine, and then introduces the m-xylylenediamine terephthalate salt into the main chain of PA6 molecule through polycondensation reaction with caprolactam, thereby modifying PA6 resin. The tensile strength and impact resistance of the modified PA6 resin are significantly improved, which can greatly expand the application range of PA6 composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a flow chart of a method for preparing a PA6 composite material according to the present invention;

[0029] FIG2 is an FTIR graph of the PA6 composite material of the present invention. DETAILED DESCRIPTION

[0030] The following is a more detailed description of the high-strength PA6 composite material and preparation method of the present invention, with reference to schematic diagrams. Preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art may modify the present invention described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as a general guideline for those skilled in the art and not as a limitation of the present invention.

[0031] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are greatly simplified and not to exact scale, and are provided solely for the purpose of assisting in the description of the embodiments of the present invention.

[0032] Example 1

[0033] The embodiment of the present invention provides a high-strength PA6 composite material, which comprises, by weight: 80 to 95 parts of caprolactam; 1 to 3 parts of benzoic acid; 10 to 30 parts of a modifying agent;

[0034] The benzoic acid is used to improve the tensile strength of the composite material, and the modification aid is used to enhance the impact resistance of the composite material.

[0035] Specifically, the PA6 composite material can be prepared in the amounts shown in the following table based on weight.

[0036] Table 1 PA6 composite material formula

[0037] In the three groups of ratios, the amount of the modifying agent was changed while keeping the amounts of other ingredients unchanged to explore the relationship between the toughness of the polystyrene composite material and the modifying agent.

[0038] After the PA6 composite material sample is prepared, the molecular structure of the PA6 composite material is characterized using an FTIR instrument. A Fourier transform infrared spectrometer (FTIR instrument) primarily consists of a Michelson interferometer and a computer. The main function of a Michelson interferometer is to split the light emitted by a light source into two beams, creating a certain optical path difference, and then recombining them to produce interference. The resulting interference pattern function contains all the frequency and intensity information of the light source. By Fourier transforming the interference pattern function using a computer, the frequency distribution of the original light source's intensity can be calculated. It overcomes the shortcomings of dispersive spectrometers, such as low resolution, low light energy output, narrow spectral range, and long measurement time. It can not only measure the absorption and reflection spectra of various gas, solid, and liquid samples, but can also be used to measure short-term chemical reactions. Currently, infrared spectrometers are widely used in electronics, chemical engineering, medicine, and other fields.

[0039] At the same time, impact tests were performed on injection-molded PA6 composite material samples using a plastic pendulum impact tester. This pendulum impact tester (also known as an intelligent pendulum impact instrument) can accurately measure the pendulum impact resistance of materials such as plastics, films, paper, composite films, and metal foils. The equipment utilizes electronic testing with a high degree of automation and is equipped with professional software that enables curve analysis, data storage, and comparison of test data.

[0040] Furthermore, the modifying agent includes terephthalic acid and m-xylenediamine, the ratio of the terephthalic acid to the m-xylenediamine is 1:1, and the terephthalic acid and the m-xylenediamine react to generate a terephthalic acid m-xylenediamine salt reinforcing agent.

[0041] Specifically, terephthalic acid reacts with m-xylylenediamine to produce m-xylylenediamine terephthalate, which is then introduced into the PA6 molecular backbone through a polycondensation reaction with caprolactam, thereby modifying the PA6 resin. The modified PA6 resin significantly improves its tensile strength and impact resistance.

[0042] Furthermore, it also includes an antioxidant, the weight portion of the antioxidant is 2 to 4 parts, and the antioxidant is used to resist the oxidative decomposition and aging of the PA6 composite material in a high temperature and high oxygen environment.

[0043] Specifically, antioxidants are primarily used to protect nylon materials from oxidative decomposition and aging in high-temperature, high-oxygen environments, thereby extending the service life of nylon products. Nylon antioxidants effectively stabilize the nylon material structure, reduce thermal decomposition reactions, and prevent yellowing, hardening, and loss of elasticity.

[0044] In a specific embodiment, the antioxidant is compounded by the antioxidant 1010 and the antioxidant 168, and the compounding ratio of the antioxidant 1010 to the antioxidant 168 is 1:(1-2).

[0045] Example 2

[0046] As shown in FIG1 , the present invention further discloses a method for preparing a high-strength PA6 composite material, comprising:

[0047] S100, weighing appropriate amounts of terephthalic acid and m-xylenediamine according to a ratio, and preparing m-xylenediamine terephthalate salt.

[0048] Specifically, the preparation method of m-phenylenediamine terephthalate is carried out according to the following steps:

[0049] First, a certain amount of m-phenylenediamine is added to deionized water, stirred and dispersed, and heated to a first temperature for dissolution.

[0050] Then, the terephthalic acid solution is added and the temperature is maintained at the second temperature until the pH reaches 7 to 8 to obtain a terephthalic acid m-phenylenediamine salt solution. During the sample preparation process, the pH value is 7.5, which is a weakly alkaline environment.

[0051] Subsequently, the m-xylylenediamine terephthalate salt solution is placed at a temperature of -2°C to 8°C. As the temperature decreases, the solubility of the m-xylylenediamine terephthalate salt decreases, causing it to precipitate. At this time, the m-xylylenediamine terephthalate salt containing a certain amount of water is obtained by suction filtration.

[0052] Finally, the m-xylylenediamine terephthalate salt containing a certain amount of water is placed in an environment with a temperature of 45° C. to 55° C. and an absolute pressure of 900 Pa to 1100 Pa for drying for 5 to 6 hours to obtain the m-xylylenediamine terephthalate salt.

[0053] S200, weighing appropriate amounts of caprolactam and m-phenylenediamine terephthalate according to a ratio and adding them into a reactor, and adding benzoic acid and an antioxidant to react.

[0054] Specifically, according to the ratio of each component in the formula of Table 1, caprolactam and m-phenylenediamine terephthalate are put into a reactor, and benzoic acid and an antioxidant are added to carry out a polycondensation reaction.

[0055] S300: Use high-purity nitrogen to replace the air in the reactor 3 to 4 times, raise the temperature to 200°C to 240°C, and maintain the pressure in the reactor at 1.2 to 1.5 MPa. Keep the temperature and pressure for 1.5 to 2.5 hours.

[0056] Specifically, during the polycondensation reaction, the reaction conditions are controlled by replacing the air in the reactor with high-purity nitrogen three to four times to reduce the impact of air components on the polycondensation reaction. The temperature is raised to 200°C to 240°C, and the pressure in the reactor is maintained at 1.2 to 1.5 MPa. The reaction is then maintained at this temperature and pressure for 1.5 to 2.5 hours.

[0057] S400, heating to 240°C ~ 260°C, maintaining the pressure in the reactor at 1.5MPa ~ 2.0MPa, maintaining the pressure for 1.2h ~ 1.8h, releasing the air to 0.05 ~ 0.15MPa, exhausting the water vapor and then vacuuming the reactor to reduce the pressure to -0.06MPa ~ -0.08MPa, maintaining the pressure for 0.8h ~ 1.2h, and obtaining PA6 composite resin.

[0058] Experimental verification:

[0059] (1) After the PA6 composite material sample was prepared, the molecular structure of the PA6 composite material was characterized by FTIR. As shown in Figure 2, the modified PA6 also showed characteristic absorption peaks of the benzene ring in the structure of terephthalic acid and m-phenylenediamine at wavenumbers 870 and 1460, indicating that the MXDA-T salt segment was successfully introduced into the molecular backbone of PA6.

[0060] (2) PA6 composite samples were produced using an injection molding machine. The PA6 raw material and PA6 composite sample bars were then subjected to impact testing using a plastic pendulum impact tester. The three groups of PA6 composite samples showed an increase in impact strength of 11.2%, 11.8%, and 11.6% compared to the original PA6.

[0061] Compared with the prior art, the present invention has at least the following beneficial effects:

[0062] The present invention generates m-xylylenediamine terephthalate by reacting terephthalic acid with m-xylylenediamine, and then introduces the m-xylylenediamine terephthalate salt into the main chain of PA6 molecule through polycondensation reaction with caprolactam, thereby modifying PA6 resin. The tensile strength and impact resistance of the modified PA6 resin are significantly improved, which can greatly expand the application range of PA6 composite materials.

[0063] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A high-strength PA6 composite material, characterized in that: According to the mass percentage, it includes: 80-95 parts of caprolactam; 1-3 parts of benzoic acid; 10-30 parts of modification aid; The benzoic acid is used to improve the tensile strength of the composite material, and the modification aid is used to enhance the impact resistance of the composite material.

2. The high-strength PA6 composite material according to claim 1, characterized in that: The modifying auxiliary agent includes terephthalic acid and m-xylylenediamine, and the terephthalic acid and m-xylylenediamine are reacted to generate a m-xylylenediamine terephthalate salt reinforcing auxiliary agent.

3. The high-strength PA6 composite material according to claim 2, characterized in that: The ratio of the terephthalic acid to the m-xylylenediamine is 1:

1.

4. The high-strength PA6 composite material according to claim 1, characterized in that: The invention also includes an antioxidant, the weight portion of which is 2 to 4 parts, and the antioxidant is used to resist the oxidative decomposition and aging of the PA6 composite material in a high temperature and high oxygen environment.

5. The high-strength PA6 composite material according to claim 4, characterized in that: The antioxidant is compounded by antioxidant 1010 and antioxidant 168.

6. The high-strength PA6 composite material according to claim 5, characterized in that: The compounding ratio of the antioxidant 1010 to the antioxidant 168 is 1:(1-2).

7. A method for preparing a high-strength PA6 composite material, characterized in that: include: Weigh appropriate amounts of terephthalic acid and meta-xylylenediamine according to a ratio, and prepare meta-xylylenediamine terephthalate; Weigh appropriate amounts of caprolactam and m-phenylenediamine terephthalate according to the ratio and put them into the reactor, and then add benzoic acid and an antioxidant to react; Use high-purity nitrogen to replace the air in the reactor 3 to 4 times, raise the temperature to 200°C to 240°C, and maintain the pressure in the reactor at 1.2 to 1.5 MPa, and keep the temperature and pressure for 1.5 to 2.5 hours; The temperature was raised to 240°C to 260°C, the pressure in the reactor was maintained at 1.5MPa to 2.0MPa, and after maintaining the pressure for 1.2h to 1.8h, the air was vented to 0.05 to 0.15MPa, and the water vapor was exhausted and then vacuumed to reduce the pressure in the reactor to -0.06MPa to -0.08MPa, and after maintaining the pressure for 0.8h to 1.2h, a PA6 composite resin was obtained.

8. The method for preparing a high-strength PA6 composite material according to claim 7, characterized in that: The preparation method of the m-phenylenediamine terephthalate salt comprises: Add a certain amount of m-phenylenediamine into deionized water, stir and disperse, and heat to a first temperature to dissolve; Adding terephthalic acid solution and maintaining the temperature at the second temperature until the pH reaches 7 to 8 to obtain a terephthalic acid m-xylylenediamine salt solution; The m-phenylenediamine terephthalate salt solution is placed at a sub-zero temperature, and the m-phenylenediamine terephthalate salt containing a certain amount of water is obtained by suction filtration; The m-xylylenediamine terephthalate salt containing a certain amount of water is placed in an environment of a temperature of 45° C. to 55° C. and an absolute pressure of 900 Pa to 1100 Pa and dried for 5 h to 6 h to obtain the m-xylylenediamine terephthalate salt.

9. The method for preparing a high-strength PA6 composite material according to claim 7, characterized in that: The first temperature is lower than the second temperature.

10. The method for preparing a high-strength PA6 composite material according to claim 9, characterized in that: The first temperature is 45°C to 50°C, and the second temperature is 50°C to 80°C.

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