Stress-whitening-resistant glass fiber reinforced polypropylene composite material capable of being subjected to laser marking as well as preparation method and application of stress-whitening-resistant glass fiber reinforced polypropylene composite material

Abstract

The invention discloses a stress-whitening-resistant glass fiber reinforced polypropylene composite material capable of being subjected to laser marking as well as a preparation method and application of the stress-whitening-resistant glass fiber reinforced polypropylene composite material. Comprising the following components: 60%-85% of polypropylene resin, 10%-30% of glass fibers, 1%-4% of a compatilizer, 0.1%-1.0% of a nucleating agent, 0.4%-0.8% of an antioxidant, 0.2%-0.5% of a heat-resistant agent, 0.3%-0.8% of a lubricant and 0.3%-0.5% of mixed toner. The composite material disclosed by the invention not only can resist stress whitening, but also can obtain excellent comprehensive mechanical properties, laser marking and tracing are carried out on production materials, and the production requirements of automobile main engine plants are met.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a laser-markable, stress-whitening-resistant glass-fiber-reinforced polypropylene composite material, and a preparation method and application thereof. Background Art

[0002] Polypropylene (PP) is a thermoplastic resin, the lightest general-purpose plastic, with good corrosion resistance, and better strength, rigidity and transparency than polyethylene. The disadvantages are poor low-temperature impact resistance and easy aging, which can be solved by modification and adding antioxidants. Glass fiber reinforced polypropylene material has improved heat resistance, strength, stress cracking resistance, rigidity and reduced shrinkage. It can be used to make axial fans in refrigerators, air conditioners and other refrigeration machines. It can also be used to manufacture high-speed washing machine pulleys, inner barrels, impellers and other parts with high mechanical properties, and used in places with high temperature resistance requirements such as rice cooker bases and handles, electronic microwave ovens, etc.

[0003] At present, the traceability requirements for materials are getting higher and higher. The laser marking of plastics is based on the high energy input of the laser to cause the polymer to carbonize or foam, thereby obtaining a mark with a large color difference from the base color. Laser marking technology can solve this problem very well. During the assembly process, some parts made of glass fiber reinforced polypropylene materials will be subjected to stress, resulting in partial whitening problems. This position is easily broken by external forces, causing the parts to fail.

[0004] Therefore, how to provide a stress-whitening resistant glass fiber reinforced polypropylene composite material, reduce the risk of local fracture due to stress whitening, and use laser marking technology to trace the source of the material is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] Based on the deficiencies in the prior art, the purpose of the present invention is to provide a laser-markable, stress-whitening-resistant glass fiber reinforced polypropylene composite material and a preparation method and application thereof. The composite material is not only stress-whitening-resistant, but also has excellent comprehensive mechanical properties. The production materials can be laser-marked and traced, meeting the production needs of automobile OEMs.

[0006] In order to achieve the above purpose, this application adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a laser-markable, stress-whitening-resistant glass fiber reinforced polypropylene composite material, which comprises the following components by weight percentage: 60% to 85% polypropylene resin, 10% to 30% glass fiber, 1% to 4% compatibilizer, 0.1% to 1.0% nucleating agent, 0.4% to 0.8% antioxidant, 0.2% to 0.5% heat-resistant agent, 0.3% to 0.8% lubricant, and 0.3% to 0.5% mixed color powder.

[0008] In the above technical solution, the polypropylene resin is at least one of a copolymer polypropylene resin, a homopolymer polypropylene resin and a high crystalline polypropylene resin.

[0009] In the above technical solution, the glass fiber is short glass fiber that has been surface treated with a coupling agent.

[0010] In the above technical solution, the compatibilizer is at least one of polypropylene grafted with maleic anhydride, polyethylene grafted with maleic anhydride and ethylene-octene copolymer grafted with maleic anhydride.

[0011] In the above technical solution, the nucleating agent is at least one of ultrafine talc, potassium benzoate and sodium benzoate.

[0012] In the above technical scheme, the antioxidant includes a primary antioxidant and a secondary antioxidant; the primary antioxidant is at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester, and the secondary antioxidant is tris[2.4-di-tert-butylphenyl]phosphite.

[0013] In the above technical solution, the heat-resistant agent is pentaerythritol tetra(3-laurylthiopropionate);

[0014] The lubricant is at least one of ethylene bis stearamide, calcium stearate and zinc stearate.

[0015] In the above technical solution, the mixed color powder is formed by mixing infrared penetrating black powder and laser marking powder in a certain proportion.

[0016] In a second aspect, the present invention provides a method for preparing the composite material, comprising the following steps:

[0017] S1: weighing the raw material components, the raw material components include: polypropylene resin 60% to 85%, glass fiber 10% to 30%, compatibilizer 1% to 4%, nucleating agent 0.1% to 1.0%, antioxidant 0.4% to 0.8%, heat resistant agent 0.2% to 0.5%, lubricant 0.3% to 0.8%, mixed color powder 0.3% to 0.5%;

[0018] S2: fully mixing the polypropylene resin, compatibilizer, nucleating agent, antioxidant, heat-resistant agent, lubricant and mixed toner in a high-speed mixer to obtain a mixed material;

[0019] S3: adding the mixed material from the main feed port and conveying it into the screw cavity of the twin-screw extruder, adding the glass fiber from the side feed port and conveying it into the screw cavity of the twin-screw extruder, heating and melting, extruding granulation, and sieving in the screw cavity to obtain the composite material.

[0020] In a third aspect, the present invention provides application of the composite material in automobile production.

[0021] The beneficial effects of the present invention are:

[0022] The composite material formula of the present invention contains polypropylene resin, which can improve the impact resistance and elongation at break of the composite material, has good strength and rigidity, is stress-resistant and not prone to whitening.

[0023] The present invention can improve the bonding force between the resin and the glass fiber and improve the mechanical properties of the composite material by adding a compatibilizer.

[0024] The invention delays the thermal oxidation aging degradation process of the composite material by adding an antioxidant and a heat-resistant agent to improve the heat resistance of the composite material and prolong the service life of the composite material.

[0025] The invention can reduce the friction between resins and between resins and glass fibers by adding lubricants, thereby improving the dispersibility of glass fibers in composite materials and improving the mechanical properties of composite materials.

[0026] The invention uses compounded mixed color powder, infrared penetrating black powder and laser marking agent to ensure that the material is not easily burnt or yellowed when marked with high power under laser (infrared light source) irradiation, and the writing is white and clear.

[0027] Therefore, the laser-markable and stress-whitening-resistant glass fiber reinforced polypropylene composite material prepared by the formula ratio and preparation method of the present invention is not only stress-whitening-resistant, but also has excellent comprehensive mechanical properties. The production materials can be laser-marked and traced, which meets the production needs of automobile main engine factories. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flow chart of a method for preparing the composite material of the present invention;

[0029] Figure 2 The stress bending resistance diagram of the tensile spline of Examples 1-3 and Comparative Examples 1-5 of the present invention, wherein the red box area is the stress whitening area after the tensile spline is repeatedly bent;

[0030] Figure 3 The laser marking effect diagrams of Examples 1-3 and Comparative Examples 1-5 of the present invention are shown. DETAILED DESCRIPTION

[0031] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. The present invention can be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and the concept of the present invention will be fully conveyed to those skilled in the art, and the present invention will only be limited by the claims.

[0032] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0033] The invention provides a laser-markable and stress-whitening-resistant glass fiber reinforced polypropylene composite material, which comprises the following components by weight percentage: 60% to 85% of polypropylene resin, 10% to 30% of glass fiber, 1% to 4% of compatibilizer, 0.1% to 1.0% of nucleating agent, 0.4% to 0.8% of antioxidant, 0.2% to 0.5% of heat-resistant agent, 0.3% to 0.8% of lubricant and 0.3% to 0.5% of mixed color powder.

[0034] By adding a compatibilizer, the bonding force between the resin and the glass fiber can be improved, and the mechanical properties of the composite material can be improved; by adding an antioxidant and a heat-resistant agent, the thermal oxidation aging degradation process of the composite material can be delayed, the heat resistance of the composite material can be improved, and the service life of the composite material can be extended; by adding a lubricant, the friction between the resin and the resin can be reduced, and the friction between the resin and the glass fiber can be reduced, the dispersion of the glass fiber in the composite material can be improved, and the mechanical properties of the composite material can be improved; by compounding a mixed color powder-infrared penetrating black powder and a laser marking agent, the material is not easy to burn or turn yellow when marked at high power under laser (infrared light source) irradiation, and the handwriting is white and clear. It can be seen that the composite material prepared by the inventive formula ratio and preparation method can not only resist stress whitening, but also obtain excellent comprehensive mechanical properties, and the production materials can be laser marked and traced, which meets the production needs of automobile OEMs.

[0035] In the present invention, the polypropylene resin is at least one of a copolymer polypropylene resin, a homopolymer polypropylene resin and a high crystalline polypropylene resin.

[0036] The polypropylene resin is preferably a blend of a copolymerized polypropylene resin and a homopolymerized polypropylene resin. Such a resin combination has a stronger ability to bind to the glass fiber, and under high temperature, high speed and high pressure injection molding conditions, the glass fiber is not easily dispersed, has better dispersibility in the resin, and can obtain a better appearance. In addition, the glass fiber is a short glass fiber surface treated with a coupling agent, which can further enhance the ability to bind to the resin and improve the strength and rigidity of the composite material.

[0037] In some possible embodiments, the copolymer polypropylene resin is a low-melting copolymer polypropylene resin with a mass melt index of ≤10g / 10min and high impact resistance. The homopolymer polypropylene resin has a mass melt index of 10 to 30g / 10min and has good fluidity, high strength and rigidity. The copolymer polypropylene resin can improve the impact resistance and elongation at break of the composite material and improve the toughness of the material. The homopolymer polypropylene resin has good strength and rigidity, is resistant to stress bending and is not prone to whitening. Adding a certain amount of homopolymer polypropylene resin to the copolymer resin, adjusting the ratio of the copolymer resin and the homopolymer resin, and adding a nucleating agent, shortening the polypropylene resin molding cycle, and improving the strength of the polypropylene resin can achieve the effect of stress whitening resistance.

[0038] In the present invention, the glass fiber is short glass fiber surface-treated with a coupling agent.

[0039] In the present invention, the compatibilizer is at least one of polypropylene grafted maleic anhydride, polyethylene grafted maleic anhydride and ethylene-octene copolymer grafted maleic anhydride. Adding the compatibilizer can improve the bonding force between the resin and the glass fiber and improve the mechanical properties of the composite material.

[0040] In the present invention, the nucleating agent is at least one of ultrafine talc, potassium benzoate and sodium benzoate. Adding the nucleating agent can shorten the molding cycle of the polypropylene resin, so that the polypropylene material can obtain higher strength and rigidity in a short period of time, and reduce the whitening phenomenon caused by stress concentration.

[0041] In the present invention, the antioxidant includes a primary antioxidant and a secondary antioxidant; the primary antioxidant is at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester and β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester, and the secondary antioxidant is tris[2,4-di-tert-butylphenyl] phosphite. The synergistic effect of the primary antioxidant and the secondary antioxidant can effectively inhibit the thermal oxidation aging degradation process of the composite material, improve the heat resistance of the composite material, and extend the service life of the composite material.

[0042] In the present invention, the heat-resistant agent is pentaerythritol tetra(3-laurylthiopropionate); the heat-resistant agent can effectively inhibit the degradation of materials caused by transition processing, prevent the breakage of polymer molecular chains, prevent the oxidation of materials, and improve the mechanical properties and service life of materials in long-term use.

[0043] In the present invention, the lubricant is at least one of ethylene bis stearic acid amide, calcium stearate and zinc stearate. By adding the lubricant, the friction between the resins and the friction between the resins and the glass fibers can be reduced, the dispersibility of the glass fibers in the composite material can be improved, and the mechanical properties of the composite material can be improved.

[0044] In the present invention, the mixed color powder is made of infrared penetrating black powder and laser marking powder in a certain proportion. By adding the mixed color powder, the material is not easily burned or yellowed when marked with high power under laser (infrared light source) irradiation, and the writing is white and clear.

[0045] like Figure 1 As shown, the present invention provides a method for preparing a laser-markable, stress-whitening-resistant glass fiber reinforced polypropylene composite material, comprising the following steps:

[0046] S1: weighing the raw material components, which include: 60% to 85% polypropylene resin, 10% to 30% glass fiber, 1% to 4% compatibilizer, 0.1% to 1.0% nucleating agent, 0.4% to 0.8% antioxidant, 0.2% to 0.5% heat resistant agent, 0.3% to 0.8% lubricant, and 0.3% to 0.5% mixed color powder.

[0047] S2: Fully mix the polypropylene resin, compatibilizer, nucleating agent, antioxidant, heat-resistant agent, lubricant and mixed color powder in a high-speed mixer to obtain a mixed material.

[0048] S3: adding the mixed material from the main feed port and conveying it into the screw cavity of the twin-screw extruder, adding the glass fiber from the side feed port and conveying it into the screw cavity of the twin-screw extruder, heating and melting in the screw cavity, extruding granulation, and sieving, so as to obtain the composite material of the present invention.

[0049] In some possible embodiments, the heating and melting temperature is 190-230°C.

[0050] The invention also provides an application of a laser-markable and stress-whitening-resistant glass-fiber-reinforced polypropylene composite material in automobile production.

[0051] Specifically, the composite material prepared by the above-mentioned formula ratio and preparation method of the present invention can be further processed by injection molding to produce products required by automobile OEMs, and the material can also be laser marked to trace the production material, which is in line with the low-carbon and environmentally friendly development concept.

[0052] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0053] Sources of components in each embodiment and comparative example:

[0054] Polypropylene resin: The copolymer polypropylene resin is Kunlun Petrochemical EPS30R, and the homopolymer polypropylene resin is Kunlun Petrochemical V30G.

[0055] Glass fiber: Short glass fiber treated with coupling agent. Jushi Group 362A

[0056] Compatibilizer: Polypropylene grafted with maleic anhydride. Coase B1.

[0057] Nucleating agent: ultrafine talc powder. Shanghai Liangjiang Titanium Dioxide Chemical Products Co., Ltd. LJ-320.

[0058] Antioxidant: including primary antioxidant and secondary antioxidant, the primary antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, Lianlong antioxidant 1010. The secondary antioxidant is tris[2.4-di-tert-butylphenyl] phosphite, Lianlong antioxidant 168. The mass ratio of the two is 1:1.

[0059] Heat resistant agent: pentaerythritol tetra(3-laurylthiopropionate). Rianlon 412S.

[0060] Lubricant: Ethylene bis stearamide. Japanese Kao EB-FF.

[0061] Mixed color powder: infrared penetrating black powder, Orion P60. Laser marking powder, Merck 8830. The two are mixed in a mass ratio of 1:1.

[0062] Example 1

[0063] The laser-markable, stress-whitening-resistant glass fiber reinforced polypropylene composite material of this embodiment includes the following components by weight percentage:

[0064]

[0065] In this embodiment, the laser-markable and stress-whitening-resistant glass fiber reinforced polypropylene composite material is prepared by the following steps:

[0066] (1) Weigh various raw materials according to the ratio.

[0067] (2) The polypropylene resin and the additives (except glass fiber) are fully mixed in a high-speed mixer to obtain a mixed material.

[0068] (3) The mixed material is added from the main feed port and conveyed into the screw cavity of the twin-screw extruder, and the glass fiber is added from the side feed port and conveyed into the screw cavity of the twin-screw extruder. The mixed material is heated and melted in the screw cavity, extruded into granules, and sieved to obtain a laser-markable and stress-whitening-resistant glass fiber reinforced polypropylene composite material.

[0069] Example 2

[0070] The laser-markable, stress-whitening-resistant glass fiber reinforced polypropylene composite material of this embodiment includes the following components by weight percentage:

[0071]

[0072] The preparation method of this embodiment is the same as that of embodiment 1.

[0073] Example 3

[0074] The laser-markable, stress-whitening-resistant glass fiber reinforced polypropylene composite material of this embodiment includes the following components by weight percentage:

[0075]

[0076] The preparation method of this embodiment is the same as that of embodiment 1.

[0077] Comparative Example 1

[0078] The glass fiber reinforced polypropylene composite material of this comparative example comprises the following components by weight percentage:

[0079] The preparation method of this comparative example is the same as that of Example 1.

[0080] Comparative Example 2

[0081] The glass fiber reinforced polypropylene composite material of this comparative example comprises the following components by weight percentage:

[0082] The preparation method of this comparative example is the same as that of Example 1.

[0083] Comparative Example 3

[0084] The glass fiber reinforced polypropylene composite material of this comparative example comprises the following components by weight percentage:

[0085]

[0086]

[0087] The preparation method of this comparative example is the same as that of Example 1.

[0088] Comparative Example 4

[0089] The glass fiber reinforced polypropylene composite material of this comparative example comprises the following components by weight percentage:

[0090]

[0091] The preparation method of this comparative example is the same as that of Example 1.

[0092] Comparative Example 5

[0093] The glass fiber reinforced polypropylene composite material of this comparative example comprises the following components by weight percentage:

[0094]

[0095] The preparation method of this comparative example is the same as that of Example 1.

[0096] The performance of the laser-markable and stress-whitening-resistant glass fiber reinforced polypropylene composite materials prepared in Examples 1-3 of the present invention and the glass fiber reinforced polypropylene composite materials prepared in Comparative Examples 1-5 were tested, and the test results are shown in Table 1 below:

[0097] Table 1 Test results

[0098]

[0099]

[0100] Through the test results of the embodiments and comparative examples, and Figure 2 and Figure 3 Discover:

[0101] (1) When using homopolymer polypropylene resin alone, the stress whitening resistance is better and it does not whiten after repeated bending.

[0102] (2) When the copolymer resin is blended with the homopolymer polypropylene resin, and the copolymer resin accounts for ≤20wt%, the stress whitening resistance effect is relatively good, and it does not whiten after repeated bending; when the copolymer resin accounts for 25wt% of the comparative example, slight whitening occurs.

[0103] (3) When using copolymer resin alone, the stress whitening resistance is the worst, and repeated bending will cause severe whitening.

[0104] (4) When mixed color powder is used, the laser marking is clear and white. When coarse carbon black or fine carbon black is used, the laser marking is yellow.

[0105] (5) When homopolymer resin is used alone, the strength and rigidity are good, but the impact toughness is low; when copolymer resin is used alone, the strength and rigidity are low, but the impact toughness is good; when homopolymer resin and copolymer resin are blended, the comprehensive mechanical properties are good.

[0106] The embodiment of the present invention selects homopolymer resin and copolymer resin for blending, and the color powder selects the solution of compounding infrared penetrating color powder and laser marking powder, which has good comprehensive mechanical properties, clear laser marking and good stress whitening resistance effect. This is because copolymer polypropylene resin can improve the impact resistance and elongation at break of composite materials, and improve the toughness of materials; homopolymer polypropylene resin has good strength and rigidity, is resistant to stress bending and is not easy to whiten; adding a certain amount of homopolymer polypropylene resin to the copolymer resin, adjusting the ratio of copolymer resin and homopolymer resin, and adding nucleating agent, shortening the molding cycle of polypropylene resin, and improving the strength of polypropylene resin can achieve the effect of stress whitening resistance; adding compatibilizer can improve the bonding force between resin and glass fiber and improve the mechanical properties of composite materials; adding antioxidant and heat-resistant agent can jointly delay the thermal oxidation aging degradation process of composite materials, improve the heat resistance of composite materials, and extend the service life of composite materials; adding lubricant can reduce the friction between resins and between resins and glass fibers, improve the dispersion of glass fibers in composite materials, and improve the mechanical properties of composite materials; by compounding mixed color powder (infrared penetrating black powder and laser marking agent), the material is not easy to burn or yellow under laser (infrared light source) irradiation, and the writing is white and clear. It can be seen that the laser-markable, stress-whitening-resistant glass fiber reinforced polypropylene composite material prepared by the formula ratio and preparation method of the present application is not only stress-whitening-resistant, but also has excellent comprehensive mechanical properties. The production materials can be laser marked and traced, which meets the production needs of automobile OEMs.

[0107] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A laser-markable, stress-whitening-resistant glass fiber reinforced polypropylene composite material, characterized in that: Calculated by weight percentage, it includes the following components: 60% to 85% of polypropylene resin, 10% to 30% of glass fiber, 1% to 4% of compatibilizer, 0.1% to 1.0% of nucleating agent, 0.4% to 0.8% of antioxidant, 0.2% to 0.5% of heat-resistant agent, 0.3% to 0.8% of lubricant, and 0.3% to 0.5% of mixed color powder.

2. The composite material according to claim 1, characterized in that: The polypropylene resin is at least one of a copolymer polypropylene resin, a homopolymer polypropylene resin and a high crystalline polypropylene resin.

3. The composite material according to claim 1, characterized in that: The glass fiber is short glass fiber surface-treated with a coupling agent.

4. The composite material according to claim 1, characterized in that: The compatibilizer is at least one of polypropylene grafted with maleic anhydride, polyethylene grafted with maleic anhydride, and ethylene-octene copolymer grafted with maleic anhydride.

5. The composite material according to claim 1, characterized in that: The nucleating agent is at least one of ultrafine talc, potassium benzoate and sodium benzoate.

6. The composite material according to claim 1, characterized in that: The antioxidant comprises a primary antioxidant and a secondary antioxidant; the primary antioxidant is at least one of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester, and the secondary antioxidant is tris[2.4-di-tert-butylphenyl]phosphite.

7. The composite material according to claim 1, characterized in that: The heat-resistant agent is pentaerythritol tetrakis (3-laurylthiopropionate); The lubricant is at least one of ethylene bis stearamide, calcium stearate and zinc stearate.

8. The composite material according to claim 1, characterized in that: The mixed color powder is formed by mixing infrared penetrating black powder and laser marking powder in a certain proportion.

9. The method for preparing the composite material according to any one of claims 1 to 8, characterized in that: Includes the following step: S1: weighing the raw material components, the raw material components include: polypropylene resin 60% to 85%, glass fiber 10% to 30%, compatibilizer 1% to 4%, nucleating agent 0.1% to 1.0%, antioxidant 0.4% to 0.8%, heat resistant agent 0.2% to 0.5%, lubricant 0.3% to 0.8%, mixed color powder 0.3% to 0.5%; S2: fully mixing the polypropylene resin, compatibilizer, nucleating agent, antioxidant, heat-resistant agent, lubricant and mixed toner in a high-speed mixer to obtain a mixed material; S3: adding the mixed material from the main feed port and conveying it into the screw cavity of the twin-screw extruder, adding the glass fiber from the side feed port and conveying it into the screw cavity of the twin-screw extruder, heating and melting, extruding granulation, and sieving in the screw cavity to obtain the composite material.

10. Use of the composite material according to any one of claims 1 to 8 in automobile production.

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