Polypropylene composite material as well as preparation method and application thereof

Abstract

The invention discloses a polypropylene composite material which comprises the following components in parts by weight: 44-86 parts of polypropylene; 1-10 parts of a surface modifier; 0.1 to 1 part of organic peroxide; 0-30 parts of a toughening agent; the surface modifier is selected from at least one of urea resin, polypropylene micronized wax and fumed silica. By introducing the surface modifier and the organic peroxide, the special adhesive force of the surface of the polypropylene composite material can be remarkably improved, the requirement of water-based paint spraying is met, and the polypropylene composite material is suitable for preparing automobile bumpers.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly to a polypropylene composite material, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of the requirements for automotive lightweighting, the spraying method based on polypropylene has become the most widely used scenario for automotive bumpers today. However, it is a relatively difficult problem that the paint is likely to peel off when the bumper is scratched. Conventional methods require the cooperation and adjustment between paint suppliers and material suppliers, resulting in slow market feedback speed and high costs.

[0003] Patent CN 108164808 A introduces a sprayable modified polypropylene composite material and a preparation method thereof. By adding polar additives and assisting with an interfacial modifier to increase the surface tension, the surface polarity of the polypropylene material is improved, making it easy to spray. However, this patent does not describe the paint adhesion after spraying. Adding too many polar additives has no problem for conventional cross-cut tests, but paint peeling will occur under high temperature and high pressure flushing. Chinese invention patent CN116855014A discloses a preparation method for an automotive bumper with high paint adhesion, which is a "four-high" material with high melt index, high impact resistance, high modulus, and high paint adhesion, but it is achieved through thermoplastic polyurethane elastomer and has a high price. Summary of the Invention

[0004] The purpose of the present invention is to provide a polypropylene composite material with good adhesion of water-based paint on the surface, a preparation method thereof, and an application thereof.

[0005] The present invention is achieved by the following technical solutions: A polypropylene composite material, by weight, comprises the following components: 44 - 86 parts of polypropylene; 1 - 10 parts of a surface modifier; 0.1 - 1 part of an organic peroxide; 0 - 30 parts of a toughening agent; The surface modifier is selected from at least one of urea-formaldehyde resin, polypropylene micro powder wax, and fumed silica.

[0006] In the polypropylene composite material of the present invention, the content of polypropylene can be 44 parts, 46 parts, 48 parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, 62 parts, 64 parts, 66 parts, 68 parts, 70 parts, 72 parts, 74 parts, 76 parts, 78 parts, 80 parts, 82 parts, 84 parts, 86 parts, etc., the content of the surface modifier can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc., the content of the organic peroxide can be 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1.0 part, etc., and the content of the toughening agent can be 0 part, 1 part, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, etc.

[0007] The average particle size range of the surface modifier described above is 0.1 - 20 microns. The melting point of the urea - formaldehyde resin is 130 - 160 °C, and the average particle size range is 0.1 - 10 microns; preferably, the average particle size range of the urea - formaldehyde resin is 3 - 7 microns.

[0008] The melting point of the polypropylene micro - powder wax described above is 130 - 140 °C, and the average particle size range is 5 - 15 microns; preferably, the average particle size range of the polypropylene micro - powder wax is 7 - 13 microns.

[0009] The test method for the melting points of the urea - formaldehyde resin and the polypropylene micro - powder wax is: ISO 11357, DSC method, with a heating rate of 10 °C / min.

[0010] The average particle size range of the fumed silica described above is 0.1 - 5 microns, and preferably, the average particle size range of the fumed silica is 2.5 - 3.5 microns.

[0011] The average particle size of the surface modifier is obtained by testing with a laser particle size analyzer.

[0012] The organic peroxide selected is at least one of dicumyl peroxide, di - tert - amyl peroxide, and di - tert - butyl peroxide. The applicant conjectures that an appropriate content of the organic peroxide can precipitate onto the material surface, thereby decomposing the material surface and further increasing its surface roughness. However, when the content of the organic peroxide is too high, it will cause severe degradation of the resin and affect other properties. Preferably, the relative molecular mass of the organic peroxide is below 300.

[0013] The melt index range of the polypropylene described above is 1 - 30 g / 10min, at 230 °C, 2.16 kg, and the test standard is ISO1133 - 2022.

[0014] The polypropylene can be homopolypropylene or copolymerized polypropylene. In the polypropylene composite material of the present invention, the polypropylene accounts for not less than 35 wt% of the total weight.

[0015] The toughening agent is selected from at least one of POE and MPOP; the POE is selected from ethylene a-olefin copolymers, preferably at least one of ethylene-butene copolymer and ethylene-octene copolymer.

[0016] Optionally, the POE can be ENGAGE 7467, POE ENGAGE 7447; the MPOP can be MPOP VL880, MPOP VL8805, etc.

[0017] By weight, it further includes 0-30 parts of filler, and the filler is selected from one of talcum powder, calcium carbonate, mica powder, and wollastonite. The particle size range of the filler can be 0.1-100 microns.

[0018] 0-3 parts of additives can be added according to actual conditions, and the additives can be antioxidants, lubricants, light stabilizers, color powders or color masters, etc.

[0019] The preparation method of the polypropylene composite material includes the following steps: According to the ratio, mix polypropylene, surface modifier, toughening agent, and filler evenly, and extrude and pelletize through a twin-screw extruder, with peroxide organic side feeding to obtain the polypropylene composite material. The barrel temperature range can be selected as 180-200 °C, and the screw speed range can be selected as 450-500 revolutions per minute.

[0020] The application of the polypropylene composite material can be used to prepare automobile bumpers.

[0021] A coated part contains a substrate layer and a coating layer provided on the surface of the substrate layer, and the substrate layer contains the above polypropylene composite material. Preferably, the coating layer is coated on the surface of the substrate layer by an aqueous coating.

[0022] The present invention has the following beneficial effects: By introducing a surface modifier, the present invention can improve the surface roughness. At the same time, by introducing peroxide organic, due to its small molecular weight, it will precipitate to the material surface, thereby decomposing the material surface and further improving its surface roughness. The polypropylene composite material of the present invention has the advantage of good adhesion of surface water-based paint. Specific Embodiments

[0023] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made. These all belong to the protection scope of the present invention.

[0024] The sources of raw materials used in the embodiments and comparative examples of the present invention are as follows: Polypropylene A: PP EP548R, from CNOOC and Shell Chemicals; Polypropylene B: PP K9010, purchased from Chemical Fiber Co., Ltd.; Urea formaldehyde resin was purchased from Huber, with a melting point of 135°C. Raw materials with a specific average particle size were obtained through screening: Urea formaldehyde resin A: average particle size of 0.2 microns; Urea formaldehyde resin B: average particle size of 3.1 microns; Urea formaldehyde resin C: average particle size of 6.7 microns; Urea formaldehyde resin D: average particle size of 9.8 microns; Urea formaldehyde resin E: average particle size of 28.6 microns; Polypropylene micronized wax was purchased from BYK, with a melting point of 150°C. Raw materials with a specific average particle size were obtained through screening: Polypropylene micronized wax A: average particle size of 5.2 microns; Polypropylene micronized wax B: average particle size of 7.0 microns; Polypropylene micronized wax C: average particle size of 12.7 microns; Polypropylene micronized wax D: average particle size of 14.5 microns; Polypropylene micronized wax E: average particle size of 23.7 microns; Fumed silica was purchased from Cabot. Raw materials with a specific average particle size were obtained through screening: Fumed silica A: average particle size of 0.1 microns; Fumed silica B: average particle size of 2.5 microns; Fumed silica C: average particle size of 3.4 microns; Fumed silica D: average particle size of 4.9 microns; Fumed silica E: average particle size of 25.1 microns; Dicumyl peroxide: LUPEROX DC, purchased from Arkema; Di-tert-amyl peroxide: LUPEROX DTA, purchased from Arkema; POE: ENGAGE 7467, purchased from DOW; MPOP: VL8805, purchased from Daelim of Korea; Talc powder: TYT-777A, particle size distribution (V, 0.9) is 8 - 10 microns, from Haicheng Tianyuan Chemical Co., Ltd.; Masterbatch: PLASBLAK®PE2772KF; Light stabilizer: UV-3808PP5, purchased from Cytec; Preparation methods of the polypropylene composites in the examples and comparative examples: According to the ratio, polypropylene, a surface modifier, a toughening agent, and a filler are mixed evenly, and then extruded and pelletized through a twin-screw extruder with peroxide organic matter side-fed to obtain the polypropylene composite. The barrel temperature range is 180 - 200 °C, and the screw speed range is 450 - 500 revolutions per minute.

[0025] Methods for various tests: (1) Sprayability: The polypropylene composite is injection-molded into a 150*100*3 mm sample plate, and AkzoNobel Coating Co., Ltd. is commissioned to spray it with water-based paint, and cross-cutting and high-temperature and high-pressure water flushing tests are arranged.

[0026] Cross-cutting test: The grid spacing for cross-cutting is 2 mm, the tape is Tesa 4657, the tape adhesion time is 5 min, and the tape peeling angle is 60°. When making the grid cutting in the cross-cutting test, it is necessary to ensure that the incision cuts into the substrate, but not too deep. The tape must be pressed tightly on the surface. After 5 min, the tape is quickly peeled off from the sample surface at an angle of 60° within 0.5 s to 1.0 s. Adhesion grade: Grade 0 means that the incision edge is very smooth and none of the squares in the grid peel off; Grade 1 means that in the inner surface of the incision, there is obvious peeling damage of no more than 5% in the cross-cutting area of each small thin skin of the coating; Grade 2 means that there are thin skins at the edges of the coating and / or on the inner surface of the incision, and there is obvious peeling damage of more than 5% but no more than 15% in the cross-cutting area; Grade 3 means that the coating peels off in large strips along all or part of each incision edge and / or peels off in all or part of different parts of this square, and there is obvious peeling damage of more than 15% but no more than 35% in the cross-cutting area; Grade 4 means that the coating peels off in large strips along each incision and / or peels off in all or part of some small squares, and there is obvious peeling damage of more than 35% but no more than 65% in the cross-cutting area; Grade 5 means that there is peeling at any degree that cannot even be classified as Grade 4. Note: Referring to ISO2409, the adhesion grade: Grade 0 is the best, and Grade 5 is the worst.

[0027] High-temperature and high-pressure water flushing test: The working pressure is 68 bar, the outlet temperature is 60 ± 2 °C, the distance from the nozzle to the specimen is 130 mm ± 1, the nozzle angle is 90° ± 2°, the test duration is 60 s, and the nozzle model is PMEG 2506-1. After the test, check the width of the paint peeling off the scribed line.

[0028] Table 1: Weight parts of each component and test results of the polypropylene composites in Examples 1 - 7 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Polypropylene A 45 60 60 60 60 60 Polypropylene B 85 Type of urea-formaldehyde resin A A A B C D A Content of urea-formaldehyde resin 1 5 10 5 5 5 5 Dicumyl peroxide 0.3 0.5 1 0.5 0.5 0.5 Di-tert-amyl peroxide 0.1 POE 15 10 10 10 10 10 MPOP 30 Talc powder 0 15 20 15 15 15 15 Color masterbatch 0.5 0.5 Light stabilizer 0.5 Adhesion grade 1 1 0 0 0 0 1 Width of paint peeling, mm 1.3 1.1 0.9 0.3 0 0.6 1.0 As can be seen from Examples 2 / 4 - 6, the examples using urea-formaldehyde resin with a preferred average particle size have a higher paint adhesion grade and the paint is less likely to peel off.

[0029] Table 2: Parts by weight of each component of the polypropylene composite materials in Examples 8 - 13 and test results Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Polypropylene A 60 60 60 60 45 85 Type of polypropylene micronized wax A B C D A A Content of polypropylene micronized wax 5 5 5 5 1 10 Dicumyl peroxide 0.5 0.5 0.5 0.5 0.3 1 POE 10 10 10 10 0 30 Talc powder 15 15 15 15 0 30 Adhesion grade 1 0 0 0 1 0 Width of paint peeling, mm 1.2 0.5 0.3 0.9 1.5 1.2 As can be seen from Examples 8 - 11, the paint adhesion grade of the examples using polypropylene micro powder wax with a preferred average particle size is higher, and the paint is less likely to fall off.

[0030] Table 3: Parts by weight of each component of the polypropylene composite materials in Examples 14 - 17 and test results Example 14 Example 15 Example 16 Example 17 Polypropylene A 60 60 60 60 Type of fumed silica A B C D Content of fumed silica 5 5 5 5 Dicumyl peroxide 0.5 0.5 0.5 0.5 POE 10 10 10 10 Talc powder 15 15 15 15 Adhesion grade 1 0 0 1 Width of paint peeling, mm 1.4 0.6 0.2 1.2 As can be seen from Examples 14 - 17, the paint adhesion grade of the examples using fumed silica with a preferred average particle size is higher, and the paint is less likely to fall off.

[0031] As can be seen from the above examples, the polypropylene composite material of the present invention has an adhesion force of more than Grade 1. Table 4: Parts by weight of each component of the polypropylene composite material in the comparative example and test results Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Polypropylene A 60 60 60 60 60 Urea-formaldehyde resin A 0 5 Urea-formaldehyde resin E 5 Polypropylene micronized wax E 5 Fumed silica E 5 Dicumyl peroxide 0.5 0 0.5 0.5 0.5 POE 10 10 10 10 10 Talc powder 15 15 15 15 15 Adhesion grade 3 4 2 2 3 Width of paint peeling, mm 3.8 6.7 2.3 1.8 3.1 As can be seen from Comparative Example 1, when the urea - formaldehyde resin is not contained, the surface roughness is insufficient and the paint adhesion is poor.

[0032] As can be seen from Comparative Example 2, when the peroxy - organic compound is not contained, the surface roughness is insufficient and the paint adhesion is poor.

Claims

1. A polypropylene composite material, characterized in that: By weight, it includes the following components: Polypropylene 44-86 parts; 1-10 parts of surface modifier; Organic peroxide 0.1-1 part; Toughening agent 0-30 parts; The surface modifier is selected from at least one of urea-formaldehyde resin, polypropylene micropowder wax and fumed silica.

2. The polypropylene composite material according to claim 1, characterized in that: The average particle size of the surface modifier is in the range of 0.1-20 microns.

3. The polypropylene composite material according to claim 2, characterized in that: The melting point of the urea-formaldehyde resin is 130-140° C., and the average particle size range is 0.1-10 microns; preferably, the average particle size range of the urea-formaldehyde resin is 3-7 microns.

4. The polypropylene composite material according to claim 2, characterized in that: The melting point of the polypropylene micropowder wax is 130-160° C., and the average particle size range is 5-15 μm; preferably, the average particle size range of the polypropylene micropowder wax is 7-13 μm.

5. The polypropylene composite material according to claim 2, characterized in that: The average particle size of the fumed silica is in the range of 0.1-5 microns, and preferably, the average particle size of the fumed silica is in the range of 2.5-3.5 microns.

6. The polypropylene composite material according to claim 1, characterized in that: The organic peroxide is selected from at least one of dicumyl peroxide, di-tert-amyl peroxide and di-tert-butyl peroxide; the melt mass flow rate of the polypropylene is in the range of 1-30 g / 10 min, 230° C., and 2.16 kg.

7. The polypropylene composite material according to claim 1, characterized in that: The toughening agent is selected from at least one of POE and MPOP; by weight, it also includes 0-30 parts of filler, the filler is selected from at least one of talc, calcium carbonate, mica powder and wollastonite; and it also includes 0-3 parts of auxiliary agent.

8. The method for preparing the polypropylene composite material according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: polypropylene, a surface modifier, a toughening agent and an optional filler are uniformly mixed according to a proportion, extruded and granulated by a twin-screw extruder, and organic peroxide is side-fed to obtain a polypropylene composite material.

9. Use of the polypropylene composite material according to any one of claims 1 to 7, characterized in that: Used to prepare automobile bumpers.

10. A coated article comprising a substrate layer and a coating layer disposed on the surface of the substrate layer, characterized in that: The substrate layer comprises the polypropylene composite material according to any one of claims 1 to 7.