Fiber reinforced polypropylene composite material and preparation method thereof

Abstract

The invention provides a fiber-reinforced polypropylene composite material and a preparation method thereof.The composite material is composed of a reinforced fiber inner core and a polypropylene base material wrapping the inner core, the reinforced fiber inner core is prepared from polypropylene resin and an ultraviolet crosslinking agent, and during preparation, after the polypropylene resin and the ultraviolet crosslinking agent are mixed according to the needed proportion, the polypropylene resin and the ultraviolet crosslinking agent are mixed according to the needed proportion; the preparation method comprises the following steps: putting a polypropylene base material into an extruder for plasticizing, melting and extruding, drawing through a die head of the extruder to obtain a reinforced fiber inner core, then coating the reinforced fiber inner core with a melt of the polypropylene base material according to a wire and cable extrusion coating method, so that the reinforced fiber inner core and the melt are fused into a whole, then cooling, pelletizing and preparing into columnar particles, and finally, carrying out ultraviolet light crosslinking on the columnar particles. The strength of the composite material is effectively improved.

Description

Technical Field

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

[0002] Polypropylene (PP) is a thermoplastic material with excellent performance and good comprehensive performance. It has the advantages of low specific gravity, environmental protection and non-toxicity, easy processing, impact strength, bending resistance and good electrical insulation. However, polypropylene has some disadvantages, such as large molding shrinkage, easy brittle cracking at low temperature, insufficient wear resistance, low heat deformation temperature, poor weather resistance, etc., which limit its use in some occasions with special requirements, such as the automotive industry. As a demand side with relatively fast growth rate and good development prospects, the demand for polypropylene will occupy a more important place. At present, domestic modified polypropylene materials have the following defects: insufficient high-temperature rigidity, large molding shrinkage, poor weather resistance and other shortcomings. High-end modified polypropylene materials that can meet the above performance mainly rely on imports. They are expensive, but the market demand is very strong. At the same time, the high temperature resistance of PP in the market is mainly improved by adding glass fiber and using glass fiber reinforcement. Due to the poor compatibility of glass fiber with polypropylene, it is difficult to disperse, has poor fluidity, and has poor reinforcement effect. Summary of the invention

[0003] The purpose of the present invention is to provide a fiber reinforced polypropylene composite material and a preparation method thereof in view of the above problems existing in the prior art.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows:

[0005] In a first aspect, the present invention provides a fiber-reinforced polypropylene composite material, the composite material is composed of a reinforcing fiber inner core and a polypropylene substrate coating the inner core, and the mass ratio of the reinforcing fiber inner core to the polypropylene substrate is 1-2:100;

[0006] The raw material composition and mass fraction of the reinforcing fiber inner core include: 80-100% polypropylene resin and 0.8-1% ultraviolet light crosslinking agent.

[0007] The diameter of the reinforcing fiber inner core is 4-6 mm, and the fineness is 1000-2000D;

[0008] The raw material composition and weight fraction of the polypropylene substrate include: 80-100% polypropylene resin and 0.9-1.5% auxiliary agent.

[0009] The raw material composition of the reinforcing fiber inner core also includes benzophenone, and the mass ratio of benzophenone to polypropylene resin is 0.3-0.5:80-100;

[0010] The ultraviolet crosslinking agent is trimethylolpropane trimethacrylate.

[0011] The raw material composition of the reinforcing fiber inner core also includes nano silicon dioxide, polyethylene wax, and additives. The mass ratio of the nano silicon dioxide, polyethylene wax, additives and polypropylene resin is 4-6:0.8-1:0.9-1.5:80-100.

[0012] The auxiliary agent comprises antioxidant 1010#, antioxidant 168# and 10# white oil, and the weight ratio of the antioxidant 1010#, antioxidant 168# and 10# white oil is 0.3-0.50.3-0.5:0.3-0.5.

[0013] In a second aspect, the present invention provides a method for preparing a fiber-reinforced polypropylene composite material, comprising:

[0014] A. Mixing polypropylene resin and ultraviolet crosslinking agent in a desired ratio, placing them in an extruder for plasticization and melt extrusion, and drawing them through the die head of the extruder, and obtaining a reinforcing fiber core after cooling and shaping;

[0015] B. placing a polypropylene substrate in an extruder for melt extrusion, and coating the obtained melt on the outside of the reinforcing fiber inner core according to the wire and cable extrusion coating method, so that the reinforcing fiber inner core and the melt are integrated, followed by cooling and pelletizing to form columnar particles;

[0016] C. The columnar particles are cross-linked by ultraviolet light to prepare a fiber-reinforced polypropylene composite material.

[0017] In step A, the temperature of the extruder is: zone 1 170±5°C, zone 2 175±5°C, zone 3 180±5°C, zone 4 185±5°C, zone 5 190±5°C, and die head 190±5°C;

[0018] In step B, the temperature of the extruder is: zone 1 170±5°C, zone 2 180±5°C, zone 3 185±5°C, zone 4 190±5°C, zone 5 190±5°C, and die head 190±5°C;

[0019] In step C, the wavelength of UV crosslinking is 254 nm, and the energy is 1 mW / cm 2 , irradiation time 5-8 seconds.

[0020] The diameter of the reinforcing fiber inner core is 4-6 mm, and the fineness is 1000-2000D;

[0021] The raw material composition and mass fraction of the polypropylene substrate include: 80-100% polypropylene resin and 0.9-1.5% additive;

[0022] In the step B, the polypropylene resin and the auxiliary agent are first mixed in a desired proportion, and then placed in an extruder for melt extrusion.

[0023] The ultraviolet crosslinking agent is trimethylolpropane trimethacrylate;

[0024] The raw material composition of the reinforcing fiber inner core also includes nano silicon dioxide, benzophenone, polyethylene wax, and an additive, and the mass ratio of the silicon dioxide, benzophenone, the additive, and the polypropylene resin is 4-6:0.3-0.5:0.9-1.5:80-100;

[0025] In the step A, polypropylene resin, ultraviolet crosslinking agent nano-silica, benzophenone, polyethylene wax and auxiliary agents are first mixed, and then placed in an extruder for plasticization and melt extrusion.

[0026] The auxiliary agent comprises antioxidant 1010#, antioxidant 168# and 10# white oil, and the weight ratio of the antioxidant 1010#, antioxidant 168# and 10# white oil is 0.3-0.50.3-0.5:0.3-0.5.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. A fiber-reinforced polypropylene composite material of the present invention is composed of a reinforcing fiber inner core and a polypropylene substrate coating the inner core, and the raw materials of the reinforcing fiber inner core include polypropylene resin and ultraviolet light crosslinking agent. On the one hand, in the composite material, the reinforcing fiber is coated with the substrate resin, and during high-temperature extrusion and high-temperature injection molding, the fiber inner core can maintain its original shape and will not melt and deform, thereby maintaining the reinforcing effect of the fiber; on the other hand, the reinforcing fiber and the substrate resin are made of the same material, so that the fiber inner core and the outer substrate are combined at the interface of the two through the force between macromolecules, and the two can be completely melted together, further improving the strength of the composite material.

[0029] 2. A method for preparing a fiber reinforced polypropylene composite material of the present invention is to first place a polypropylene substrate in an extruder for melt extrusion, and the obtained melt is coated on the outside of a reinforcing fiber core according to a wire and cable extrusion coating method to form columnar particles, and then the fiber core is cross-linked and shaped by ultraviolet light, while the outer polypropylene substrate will not be cross-linked under ultraviolet light. Therefore, the composite material finally prepared is a thermoplastic material and has the characteristic of being repeatedly heated and melted for use. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with specific implementation modes.

[0031] The main raw materials used in the present invention are described as follows:

[0032] Polypropylene resin: model T30S, melt index 2.0g / 10min;

[0033] Nano-silicon dioxide: white powder, reinforcing agent;

[0034] Benzophenone: white crystalline powder, cross-linking aid;

[0035] Trimethylolpropane trimethacrylate: colorless or slightly yellow transparent liquid, UV crosslinking agent;

[0036] Polyethylene wax: white powder, lubricant;

[0037] Antioxidant 1010: white powder, anti-thermal oxidation;

[0038] Antioxidant 168: white powder, anti-thermal oxidation;

[0039] No. 10 white oil: transparent oily liquid.

[0040] Embodiment 1:

[0041] A fiber-reinforced polypropylene composite material, comprising a reinforcing fiber inner core and a polypropylene substrate covering the inner core, wherein the mass ratio of the reinforcing fiber inner core to the polypropylene substrate is 1.5:100;

[0042] The inner core of the reinforcing fiber has a diameter of 5 mm and a fineness of 1500D. The raw material composition and mass fraction thereof are: 80 polypropylene resin, 4 nano-silicon dioxide, 0.3 benzophenone, 0.8 ultraviolet light crosslinking agent trimethylolpropane trimethacrylate, 0.8 polyethylene wax, 0.3 antioxidant 1010#, 0.3 antioxidant 168#, and 0.3 10# white oil. The raw material composition and mass fraction thereof of the polypropylene substrate are: 80 polypropylene resin, 0.3 antioxidant 1010#, 0.3 antioxidant 168#, and 0.3 10# white oil.

[0043] The preparation method of the composite material comprises:

[0044] The first step is to add the raw materials required for the reinforced fiber core into a high-speed mixer, mix at room temperature for 3-5 minutes, and then discharge the mixed materials into a single-screw extruder for plasticization and melt extrusion, draw the wire through the die head of the extruder, and then cool and shape it in a cooling water tank, traction and stretching, and wind it into a roll for use. Among them, the working temperature of the extruder is: 170±5℃ in zone 1, 175±5℃ in zone 2, 180±5℃ in zone 3, 185±5℃ in zone 4, 190±5℃ in zone 5, and 190±5℃ in die head.

[0045] The second step is to add the raw materials required for the polypropylene substrate into a high-speed mixer, mix at room temperature for 3-5 minutes, and then discharge them into the extruder for melt extrusion. According to the method of wire and cable extrusion coating, the wire drawing coil prepared in the first step is used as the inner layer, and the outer layer is extruded and coated with the polypropylene substrate melt, so that the inner layer fiber and the outer layer melt are integrated, and then cooled in a cooling water tank, pelletized by a pelletizer, and prepared into 1mm×1mm columnar particles. Among them, the working temperature of the extruder is: 170±5℃ in zone 1, 180±5℃ in zone 2, 185±5℃ in zone 3, 190±5℃ in zone 4, 190±5℃ in zone 5, and 190±5℃ in the die head.

[0046] The third step is to irradiate and crosslink the columnar particles through an ultraviolet crosslinking machine to obtain a fiber-reinforced polypropylene composite material. The wavelength of the ultraviolet crosslinking is 254nm and the energy is 1mW / cm 2 , irradiation time 6 seconds.

[0047] Embodiment 2:

[0048] The steps are the same as in Example 1, except that:

[0049] The raw material composition and mass fraction of the reinforcing fiber inner core are: 90 polypropylene resin, 5 nano-silicon dioxide, 0.4 benzophenone, 0.9 trimethylolpropane trimethacrylate, 0.9 polyethylene wax, 0.4 antioxidant 1010#, 0.4 antioxidant 168#, 0.4 10# white oil. The raw material composition and mass fraction of the polypropylene substrate are: 90 polypropylene resin, 0.4 antioxidant 1010#, 0.4 antioxidant 168#, 0.4 10# white oil.

[0050] Embodiment 3:

[0051] The steps are the same as in Example 1, except that:

[0052] The raw material composition and mass fraction of the reinforcing fiber inner core are: 100 polypropylene resin, 6 nano-silicon dioxide, 0.5 benzophenone, 1.0 trimethylolpropane trimethacrylate, 1.0 polyethylene wax, 0.5 antioxidant 1010#, 0.5 antioxidant 168#, 0.5 10# white oil. The raw material composition and mass fraction of the polypropylene substrate are: 100 polypropylene resin, 0.5 antioxidant 1010#, 0.5 antioxidant 168#, 0.5 10# white oil.

[0053] Comparative Example 1:

[0054] This product is a commercially available modified polypropylene insulation material. It is a modified polypropylene material for submersible pump cables produced by Dongying Oilfield Cable Factory. The model is: Japan JPC, LR21V, with a glass fiber content of 10%.

[0055] Comparative Example 2:

[0056] A fiber-reinforced polypropylene composite material, whose raw material composition and mass fraction are: 80 polypropylene resin, 9 reinforcing fiber, 0.3 antioxidant 1010#, 0.3 antioxidant 168#, 0.3 10# white oil, and the reinforcing fiber is the same as the reinforcing fiber core in Example 2.

[0057] The preparation method of the composite material is as follows: after the reinforcing fiber core is cut into short fibers of 3 mm in length, the fibers are added into a high-speed mixer together with polypropylene resin, antioxidant 1010#, antioxidant 168#, and 10# white oil in a required proportion, mixed at room temperature for 3-5 minutes, and then discharged into an extruder for melt extrusion. The working temperature of the extruder is: 170±5℃ for zone 1, 180±5℃ for zone 2, 185±5℃ for zone 3, 190±5℃ for zone 4, 190±5℃ for zone 5, and 190±5℃ for the die head.

[0058] In order to investigate the performance of the composite material of the present invention, performance tests on high temperature rigidity, molding shrinkage, weather resistance, etc. were performed on Example 2 and Comparative Documents 1-2, and the results are shown in Table 1:

[0059] Table 1 Performance test results of each material

[0060]

[0061]

[0062] It can be seen from Table 1 that the various properties of the product of Example 2 are better than those of Comparative Example 1; although the molding shrinkage and Rockwell hardness of the product of Comparative Example 2 are better than those of the product of Example 2, other properties are lower than those of the product of Example 2, especially the elongation at break, which is greatly reduced to 180%.

Claims

1. A fiber-reinforced polypropylene composite material, characterized in that: The composite material is composed of a reinforcing fiber inner core and a polypropylene substrate covering the inner core, and the mass ratio of the reinforcing fiber inner core to the polypropylene substrate is 1-2:100; The raw material composition and mass fraction of the reinforcing fiber inner core include: 80-100% polypropylene resin and 0.8-1% ultraviolet light crosslinking agent.

2. The fiber-reinforced polypropylene composite material according to claim 1, characterized in that: The diameter of the reinforcing fiber inner core is 4-6 mm, and the fineness is 1000-2000D; The raw material composition and weight fractions of the polypropylene substrate include: 80-100% polypropylene resin and 0.9-1.5% auxiliary agent.

3. The fiber-reinforced polypropylene composite material according to claim 1 or 2, characterized in that: The raw material composition of the reinforcing fiber inner core also includes benzophenone, and the mass ratio of benzophenone to polypropylene resin is 0.3-0.5:80-100; The ultraviolet crosslinking agent is trimethylolpropane trimethacrylate.

4. The fiber-reinforced polypropylene composite material according to claim 2, characterized in that: The raw material composition of the reinforcing fiber inner core also includes nano silicon dioxide, polyethylene wax, and additives. The mass ratio of the nano silicon dioxide, polyethylene wax, additives and polypropylene resin is 4-6:0.8-1:0.9-1.5:80-100.

5. The fiber-reinforced polypropylene composite material according to claim 4, characterized in that: The auxiliary agent comprises antioxidant 1010#, antioxidant 168# and 10# white oil, and the weight ratio of the antioxidant 1010#, antioxidant 168# and 10# white oil is 0.3-0.50.3-0.5:0.3-0.

5.

6. A method for preparing the fiber-reinforced polypropylene composite material according to claim 1, characterized in that: The preparation method comprises: A. Mixing polypropylene resin and ultraviolet crosslinking agent in a desired ratio, placing them in an extruder for plasticization and melt extrusion, and drawing them through the die head of the extruder, and obtaining a reinforcing fiber core after cooling and shaping; B. placing a polypropylene substrate in an extruder for melt extrusion, and coating the obtained melt on the outside of the reinforcing fiber inner core according to the wire and cable extrusion coating method, so that the reinforcing fiber inner core and the melt are integrated, followed by cooling and pelletizing to form columnar particles; C. The columnar particles are cross-linked by ultraviolet light to prepare a fiber-reinforced polypropylene composite material.

7. The method for preparing a fiber-reinforced polypropylene composite material according to claim 6, characterized in that: In step A, the temperature of the extruder is: zone 1 170±5°C, zone 2 175±5°C, zone 3 180±5°C, zone 4 185±5°C, zone 5 190±5°C, and die head 190±5°C; In step B, the temperature of the extruder is: zone 1 170±5°C, zone 2 180±5°C, zone 3 185±5°C, zone 4 190±5°C, zone 5 190±5°C, and die head 190±5°C; In step C, the wavelength of UV crosslinking is 254 nm, and the energy is 1 mW / cm 2 , irradiation time 5-8 seconds.

8. The method for preparing a fiber-reinforced polypropylene composite material according to claim 6 or 7, characterized in that: The diameter of the reinforcing fiber inner core is 4-6 mm, and the fineness is 1000-2000D; The raw material composition and mass fraction of the polypropylene substrate include: 80-100% polypropylene resin and 0.9-1.5% additive; In the step B, the polypropylene resin and the auxiliary agent are first mixed in a desired proportion, and then placed in an extruder for melt extrusion.

9. The method for preparing a fiber-reinforced polypropylene composite material according to claim 8, characterized in that: The ultraviolet crosslinking agent is trimethylolpropane trimethacrylate; The raw material composition of the reinforcing fiber inner core also includes nano silicon dioxide, benzophenone, polyethylene wax, and an additive, and the mass ratio of the silicon dioxide, benzophenone, the additive, and the polypropylene resin is 4-6:0.3-0.5:0.9-1.5:80-100; In the step A, polypropylene resin, ultraviolet crosslinking agent nano-silica, benzophenone, polyethylene wax and auxiliary agents are first mixed, and then placed in an extruder for plasticization and melt extrusion.

10. The method for preparing a fiber-reinforced polypropylene composite material according to claim 9, characterized in that: The auxiliary agent comprises antioxidant 1010#, antioxidant 168# and 10# white oil, and the weight ratio of the antioxidant 1010#, antioxidant 168# and 10# white oil is 0.3-0.50.3-0.5:0.3-0.5.

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