Preparation method of polypropylene glass fiber composite material with high temperature discoloration resistance and high electromagnetic compatibility

Abstract

The invention discloses a preparation method of a polypropylene glass fiber composite material with high temperature discoloration resistance and high electromagnetic compatibility, which comprises the following steps: raw material preparation: preparing the following components in percentage by mass: 60-80 parts of polypropylene resin, 10-20 parts of low dielectric fiber, 1-3 parts of titanium dioxide and 0.5-1.5 parts of coupling agent; the preparation method comprises the following steps: 1, carrying out pretreatment and melt blending on the raw materials, carrying out melt blending on the treated raw materials at 200-240 DEG C to obtain a composite material melt, carrying out granulation, and carrying out granulation on the composite material melt through a granulator to obtain composite material particles, and 2, carrying out injection molding, heating the composite material particles to 220-260 DEG C, carrying out extrusion molding, and carrying out cooling to room temperature to obtain the conductive material. And performing injection molding through an injection molding machine. By adding the low-dielectric fiber, the conductive material mixture and the titanium dioxide and optimizing the proportion and the processing technology of all the components, the prepared polypropylene glass fiber composite material has excellent high-temperature discoloration resistance, high electromagnetic compatibility and low oil absorption value, and can meet the application requirements in the high-end field.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and in particular relates to a method for preparing a high-temperature color-changing resistant and highly electromagnetic compatible polypropylene glass fiber composite material. Background Art

[0002] Polypropylene (PP), as a general-purpose plastic, has the characteristics of low density, good chemical corrosion resistance, and excellent mechanical properties. It is widely used in automobiles, home appliances, packaging and other fields. With the energy and intelligence of new energy in the automotive industry, the number of electronic components in automobiles is increasing, and the requirements for the electromagnetic compatibility of materials have increased. However, pure polypropylene has the disadvantages of poor heat resistance, poor electromagnetic shielding performance, and high oil absorption, which limits its application in some high-end fields. In the prior art, there have been some studies on the modification of polypropylene, such as adding glass fiber (GF) to improve its mechanical properties and heat resistance, and adding a conductive material mixture to improve its electromagnetic shielding performance. However, these modification methods often find it difficult to simultaneously take into account the performance requirements of high temperature discoloration resistance, high electromagnetic compatibility and low oil absorption. Therefore, it is of great practical significance to improve the comprehensive performance of polypropylene through modification.

[0003] The Chinese invention patent with the publication number CN102863697B discloses a stress-whitening resistant modified polypropylene material, which includes the following components by weight: 60-83 parts of polypropylene resin, 10-25 parts of filler, 5-15 parts of polyethylene, 0.2-1.0 parts of antioxidant, 0.2-1.0 parts of lubricant, 0.3-2 parts of titanium dioxide and 0.01-0.3 parts of pigment, the particle size of titanium dioxide is 0.1-0.5 μm, and by adding titanium dioxide and combining with other components, the stress whitening phenomenon of polypropylene is reduced, the production cost is reduced, and the good mechanical properties of the material can be maintained. Only one property of polypropylene is changed, and the comprehensive performance of polypropylene needs to be improved. Summary of the invention

[0004] In order to solve the above problems, the present invention aims to provide a method for preparing a polypropylene glass fiber composite material that is resistant to high temperature discoloration and has high electromagnetic compatibility.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: a method for preparing a high temperature discoloration resistant and high electromagnetic compatibility polypropylene glass fiber composite material, comprising the following steps:

[0006] Step 1: raw material preparation, including the following components by mass percentage: 60-80 parts of polypropylene resin, 10-20 parts of low dielectric fiber, 1-3 parts of titanium dioxide, 0.5-1.5 parts of coupling agent, 0.1-0.5 parts of antioxidant, and 8-15 parts of conductive material mixture;

[0007] Step 2: Raw material pretreatment;

[0008] Step 3: melt blending, melt blending the processed raw materials at a temperature of 200-240° C. to obtain a composite material melt;

[0009] Step 4: Granulation, granulating the composite material melt through a granulator to obtain composite material particles;

[0010] Step 5: Injection molding, heating the composite material particles to 220-260°C and injection molding through an injection molding machine.

[0011] Furthermore, the conductive material mixture in step 1 includes one or more combinations of carbon nanotubes, polyphenylene ether, nylon, a compatibilizer, zinc sulfide, a lubricant, a light aging agent, and an anti-glass fiber exposure agent.

[0012] Furthermore, the raw material pretreatment in step 2 includes surface cleaning of the low dielectric fiber and drying of the conductive material mixture.

[0013] Furthermore, the step 3 is to add the low dielectric fiber pretreated in step 2, the conductive material mixture, titanium dioxide, coupling agent, antioxidant and polypropylene resin into a twin-screw extruder for mixing.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. The present invention adds low dielectric fiber, a conductive material mixture and titanium dioxide, and optimizes the ratio and processing technology of each component to prepare a polypropylene glass fiber composite material with excellent high temperature discoloration resistance, high electromagnetic compatibility and low oil absorption value, and its comprehensive performance is improved, which can meet the application requirements of high-end fields.

[0016] 2. The method of the present invention has simple process, is easy to operate, and is suitable for industrial production. DETAILED DESCRIPTION

[0017] The present invention is further described below in conjunction with specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to common technical knowledge and customary means in the field are included in the scope of the present invention.

[0018] A method for preparing a polypropylene glass fiber composite material with high temperature discoloration resistance, high electromagnetic compatibility and low oil absorption value, comprising the following steps:

[0019] Raw material preparation: weigh the following raw materials according to mass percentage: 60-80 parts of polypropylene resin, 10-20 parts of low dielectric fiber, 1-3 parts of titanium dioxide, 0.5-1.5 parts of coupling agent, 0.1-0.5 parts of antioxidant, and 8-15 parts of conductive material mixture.

[0020] A method for preparing a polypropylene glass fiber composite material having high temperature discoloration resistance, high electromagnetic compatibility and low oil absorption value comprises the following steps:

[0021] Step 1: raw material preparation, including the following components by mass percentage: 60-80 parts of polypropylene resin, 10-20 parts of low dielectric fiber, 1-3 parts of titanium dioxide, 0.5-1.5 parts of coupling agent, 0.1-0.5 parts of antioxidant, and 8-15 parts of conductive material mixture;

[0022] Step 2: Raw material pretreatment;

[0023] Step 3: melt blending, melt blending the processed raw materials at a temperature of 200-240° C. to obtain a composite material melt;

[0024] Step 4: Granulation, granulating the composite material melt through a granulator to obtain composite material particles;

[0025] Step 5: Injection molding, heating the composite material particles to 220-260°C and injection molding through an injection molding machine.

[0026] The conductive material mixture in step 1 includes the following components in percentage by mass: 45-65 parts of carbon nanotubes, 10-15 parts of polyphenylene ether, 10-15 parts of nylon, 6-11 parts of compatibilizer, 2-3 parts of lubricant, 4-5 parts of light aging agent, 1-3 parts of zinc sulfide, and 2-3 parts of anti-glass fiber exposure agent.

[0027] Embodiment 1:

[0028] (1) Raw material preparation: Weigh 73.5 parts of polypropylene resin, 15 parts of low dielectric fiber, 8 parts of conductive material mixture, 2 parts of titanium dioxide, 1.2 parts of coupling agent, and 0.3 parts of antioxidant. The specific parts of the conductive mixture are as follows: 56 parts of carbon nanotubes, 13 parts of polyphenylene ether, 13 parts of nylon, 8 parts of compatibilizer, 2 parts of lubricant, 4 parts of light aging agent, 1.5 parts of zinc sulfide, and 2.5 parts of anti-glass fiber exposure agent.

[0029] (2) Raw material pretreatment: The low dielectric fiber is surface treated to make its surface clean and improve its compatibility with polypropylene; the conductive material mixture is dried to remove moisture.

[0030] (3) Melt blending: The pretreated low dielectric fiber, conductive material mixture, titanium dioxide, coupling agent and antioxidant are added to a twin-screw extruder together with polypropylene resin, and melt blended at a temperature of 220° C. to obtain a composite material melt.

[0031] (4) Granulation: The composite material melt is granulated by a granulator to obtain composite material particles.

[0032] (5) Injection molding: The composite material particles are heated to 240° C. and injection molded by an injection molding machine to obtain a polypropylene glass fiber composite material product with high temperature discoloration resistance, high electromagnetic compatibility, and low oil absorption value.

[0033] Performance Testing:

[0034] The composite material product prepared in Example 1 was tested for performance, and the results were as follows:

[0035] High temperature color change resistance: After heating at 250℃ for 2 hours, there is no obvious color change.

[0036] Electromagnetic shielding performance: In the frequency range of 1-3GHz, the shielding effectiveness reaches 40dB.

[0037] Oil absorption performance: After being immersed in edible oil for 24 hours at room temperature, the oil absorption rate is only 1.2%.

[0038] Comparative Example 1:

[0039] Titanium dioxide is not added, and zinc sulfide is not added to the conductive mixture, and the other steps are the same as in Example 1. The performance test results are: after heating at 250° C. for 2 hours, the color becomes obviously darker, and the test data, the a value becomes reddish, and the b value becomes yellowish.

[0040] Comparative Example 2:

[0041] No conductive material mixture is added, and other steps are the same as those in Example 1. The performance test results show that within the frequency range of 1-3 GHz, the shielding effectiveness is only 10 dB.

[0042] Comparative Example 3:

[0043] No coupling agent was added, and other steps were the same as in Example 1. The performance test results showed that the mechanical properties of the composite material product were significantly reduced.

[0044] Implementation Case 1:

[0045] When conventional polypropylene materials are used to manufacture engine compartment components, it is found that the components are prone to discoloration in high temperature environments and have serious electromagnetic interference problems. The polypropylene glass fiber composite material prepared by the preparation method provided by the present invention is heated at 250°C for 2 hours, and the color does not change significantly. At the same time, in the frequency range of 1-3GHz, the shielding effectiveness reaches 40dB, which effectively solves the above problems.

[0046] Implementation Case 2:

[0047] The polypropylene glass fiber composite material prepared by the method of the present invention for the microwave oven shell is immersed in edible oil for 24 hours at room temperature, and the oil absorption rate is only 1.2%, which meets the requirement of low oil absorption rate.

[0048] in conclusion:

[0049] The present invention optimizes the raw material ratio and processing technology to prepare a polypropylene glass fiber composite material with high temperature discoloration resistance, high electromagnetic compatibility and low oil absorption value, which has excellent comprehensive performance and can meet the application requirements of high-end fields. The method is simple in process, easy to operate and suitable for industrial production.

[0050] The above is a detailed introduction to the preparation method of the high temperature color change resistant and high electromagnetic compatibility polypropylene glass fiber composite material provided by the present invention. In this article, specific examples are used to illustrate the structure and working principle of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a high temperature discoloration resistant and high electromagnetic compatibility polypropylene glass fiber composite material, characterized in that: The following steps are included: Step 1: raw material preparation, including the following components by mass: 60-80 parts of polypropylene resin, 10-20 parts of low dielectric fiber, 1-3 parts of titanium dioxide, 0.5-1.5 parts of coupling agent, 0.1-0.5 parts of antioxidant, and 8-15 parts of conductive material mixture; Step 2: Raw material pretreatment; Step 3: melt blending, melt blending the processed raw materials at a temperature of 200-240° C. to obtain a composite material melt; Step 4: Granulation, granulating the composite material melt through a granulator to obtain composite material particles; Step 5: Injection molding, heating the composite material particles to 220-260°C and injection molding through an injection molding machine.

2. The method for preparing the high temperature color change resistant and high electromagnetic compatibility polypropylene glass fiber composite material according to claim 1, characterized in that: The conductive material mixture in step 1 includes one or more combinations of carbon nanotubes, polyphenylene ether, nylon, a compatibilizer, a lubricant, a light aging agent, zinc sulfide, and an anti-glass fiber exposure agent.

3. The method for preparing the high temperature color change resistant and high electromagnetic compatibility polypropylene glass fiber composite material according to claim 1, characterized in that: The raw material pretreatment in step 2 includes cleaning the surface of the low dielectric fiber and drying the conductive material mixture.

4. The method for preparing the high temperature color change resistant and high electromagnetic compatibility polypropylene glass fiber composite material according to claim 1, characterized in that: The step 3 is to add the low dielectric fiber pretreated in step 2, the conductive material mixture, titanium dioxide, coupling agent, antioxidant and polypropylene resin into a twin-screw extruder for mixing.