Scratch-resistant easy-to-color polypropylene composite material and preparation method and application thereof

Abstract

The present application relates to a kind of scratch-resistant easy-to-color polypropylene composite material and its preparation method and application, belong to the composition technical field of polymer compound.The scratch-resistant easy-to-color polypropylene composite material of the present application includes the following weight parts of component: polypropylene resin 50~99 parts, toughening agent 0~20 parts, filler 0~25 parts, flake graphite 0.05~1.1 parts, scratch-resistant agent 0.5~4 parts;The flake graphite includes flake graphite A and flake graphite B, the mesh number of the flake graphite A is ≥1000 mesh;The mesh number of the flake graphite B is ≤400 mesh, and the flake layer structure between flake graphite B is filled with scratch-resistant agent.The polypropylene composite material not only has excellent scratch resistance, but also has good coloring performance.

Description

Technical Field

[0001] This invention relates to the field of polymer composition technology, and more particularly to a scratch-resistant and easily colored polypropylene composite material, its preparation method, and its application. Background Technology

[0002] Polypropylene (PP) is a polymer formed by the free radical polymerization of propylene monomers. Due to its excellent electrical insulation, chemical resistance, heat resistance, and fatigue resistance, it is widely used in automotive parts, electronics, packaging materials, and pipe fittings, especially in automotive parts where its usage far exceeds that of other types of plastics. However, due to PP's relatively high low-temperature brittleness and poor aging resistance, toughening and filling modifications are often necessary to better meet the application requirements of automotive parts. Furthermore, automotive parts typically undergo numerous stages from manufacturer to vehicle assembly, including transportation, handling, and assembly. Especially after interior parts are installed and reach the consumer, they are inevitably subject to scratches from sharp objects (such as keys). This can cause brittle fracture of the PP material under normal, sliding, or lateral forces, resulting in scratches that severely affect the overall aesthetics of the automotive interior parts.

[0003] To minimize the impact on the aesthetics of automotive interior parts during use, scratch-resistant agents are typically added to polypropylene materials to improve their scratch resistance. Currently, amide-based or silicone-based scratch-resistant agents are most commonly used in modified polypropylene materials. Among them, amide-based scratch-resistant agents, represented by erucamide or oleamide, can quickly migrate to the material surface to form a thin lubricating layer, giving the material good scratch resistance. However, they tend to cause the surface of the parts to become sticky and easily release volatile gases. On the other hand, silicone-based scratch-resistant agents, represented by silicone, have poor compatibility with polypropylene, and with increasing dosage, they can easily lead to appearance problems such as flow marks or bright spots on polypropylene parts.

[0004] To address the problems associated with commonly used scratch-resistant agents, researchers have begun searching for suitable scratch-resistant synergists to reduce the dosage of amide or silicone-based scratch-resistant agents while effectively improving the scratch resistance of polypropylene materials. For example, prior art (CN112480551A) discloses a polypropylene composition and its preparation method, using flake graphite as a scratch-resistant synergist. The plasticity and lubricity of flake graphite are utilized to improve the surface scratch resistance of the polypropylene material. While automotive interior parts prepared with this polypropylene composition show some improvement in scratch resistance, they still fall short of meeting consumers' higher aesthetic demands for automotive interior parts. Furthermore, in actual production, different colorants are often added to meet consumers' diverse color requirements for automotive interior parts, but existing scratch-resistant polypropylene materials have poor coloring properties. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a scratch-resistant and easily colored polypropylene composite material, its preparation method, and its application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a scratch-resistant and easily colored polypropylene composite material, comprising the following components by weight: 50-99 parts of polypropylene resin, 0-20 parts of toughening agent, 0-25 parts of filler, 0.05-1.1 parts of flake graphite, and 0.5-4 parts of scratch-resistant agent.

[0008] The flake graphite includes flake graphite A and flake graphite B, wherein the mesh size of flake graphite A is ≥1000 mesh; the mesh size of flake graphite B is ≤400 mesh, and the flake structure of flake graphite B is filled with a scratch-resistant agent.

[0009] This invention combines small-flake graphite of a specific particle size with large-flake graphite of a specific particle size, with scratch-resistant agent filling the spaces between the flakes. This not only improves the coloring properties of polypropylene composites using small-flake graphite, but also facilitates the migration of the scratch-resistant agent to the surface of the polypropylene composite during the migration process. Furthermore, it enables the scratch-resistant agent between the flakes of large-flake graphite to quickly migrate to the surface of the polypropylene composite to form a lubricating layer. In addition, the small-flake graphite can be better dispersed between the large-flake graphite to form a continuous graphite thermally conductive layer, thereby effectively dispersing the heat generated when the polypropylene composite rubs against metal or other sharp hard objects, thus significantly improving the scratch resistance of the polypropylene composite.

[0010] In the scratch-resistant and easily colored polypropylene composite material, the mass fraction of polypropylene resin is greater than or equal to 45%. The polypropylene resin can be at least one of homopolymer polypropylene, block copolymer polypropylene, or random copolymer polypropylene. The polypropylene resin conforms to ISO 1133-2011 standard, and the melt flow rate at 230℃ and 2.16kg is 10–30 g / 10 min. The toughening agent mentioned above is a conventional toughening agent suitable for polypropylene systems. The toughening agent conforms to ISO 1133-2011 standard, and the melt flow rate at 190℃ and 2.16kg is 0.1–10 g / 10 min.

[0011] Optionally, the weight percentages of polypropylene resin in the above-mentioned scratch-resistant and easily colored polypropylene composite material can be 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, or 95 parts; the weight percentages of toughening agent can be 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, or 18 parts; the weight percentages of filler can be 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, or 24 parts; the weight percentages of flake graphite can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, or 0.9 parts; and the weight percentages of scratch-resistant agent can be 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, or 3.5 parts.

[0012] Furthermore, the above-mentioned flake graphite A with a mesh count ≥ 1000 mesh means that the particle size of flake graphite A is less than or equal to the sieve aperture (13μm) corresponding to a 1000 mesh sieve, and the flake graphite B with a mesh count ≤ 400 mesh means that the particle size of flake graphite B is greater than or equal to the sieve aperture (38μm) corresponding to a 400 mesh sieve.

[0013] As a preferred embodiment of the scratch-resistant and easily colored polypropylene composite material of the present invention, the scratch-resistant and easily colored polypropylene composite material comprises the following components in parts by weight: 60-80 parts of polypropylene resin, 5-15 parts of toughening agent, 10-20 parts of filler, 0.1-1 parts of flake graphite, and 1-3 parts of scratch-resistant agent.

[0014] In a preferred embodiment of the scratch-resistant and easily colored polypropylene composite material of the present invention, the mesh size of the flake graphite A is 1000 to 2000 mesh, which is equivalent to the average particle size of the flake graphite A being between 6.5 and 13 μm.

[0015] In a preferred embodiment of the scratch-resistant and easily colored polypropylene composite material of the present invention, the mesh size of the flake graphite B is 325 to 400 mesh, which is equivalent to the average particle size of the flake graphite B being between 38 and 45 μm.

[0016] In a preferred embodiment of the scratch-resistant and easily colored polypropylene composite material of the present invention, the mass ratio of flake graphite A to flake graphite B is 1:(0.3-3). Optionally, the mass ratio of flake graphite A to flake graphite B can be 1:0.4, 1:0.6, 1:0.8, 1:1, 1:1.5, 1:2, or 1:2.5.

[0017] In a preferred embodiment of the scratch-resistant and easily colored polypropylene composite material of the present invention, the flake graphite B is obtained by melt extrusion of flake graphite with a mesh size ≤400 and a portion of scratch-resistant agent. Optionally, the mass ratio of flake graphite with a mesh size ≤400 to the portion of scratch-resistant agent in the flake graphite B is (0.1~1):(0.001~0.008), preferably (0.2~0.8):0.004, specifically 0.15:0.004, 0.25:0.004, 0.3:0.004, 0.35:0.004, 0.4:0.004, 0.5:0.004, 0.6:0.004, 0.7:0.004, or 0.9:0.004.

[0018] As a preferred embodiment of the scratch-resistant and easily colored polypropylene composite material of the present invention, the toughening agent includes at least one of ethylene-octene copolymer, ethylene-butene copolymer, ethylene propylene diene monomer (EPDM) rubber, and ethylene-vinyl acetate copolymer.

[0019] In a preferred embodiment of the scratch-resistant and easily colored polypropylene composite material of the present invention, the filler is at least one of talc, calcium carbonate, mica powder, barium sulfate, and wollastonite.

[0020] As a preferred embodiment of the scratch-resistant and easily colored polypropylene composite material of the present invention, the scratch-resistant agent is at least one of amide-based scratch-resistant agents and organosilicon-based scratch-resistant agents; specifically, the scratch-resistant agent is at least one of vinyl bis-stearamide (EBS), oleamide, erucamide, and silicone.

[0021] As a preferred embodiment of the scratch-resistant and easily colored polypropylene composite material of the present invention, the components of the scratch-resistant and easily colored polypropylene composite material further include 0.1 to 3 parts by weight of processing aids, wherein the processing aids include at least one of antioxidants, heat stabilizers, and light stabilizers.

[0022] As a preferred embodiment of the scratch-resistant and easily colored polypropylene composite material of the present invention, the components of the scratch-resistant and easily colored polypropylene composite material further include carbon black, and the mass fraction of carbon black relative to the scratch-resistant and easily colored polypropylene composite material is 0.5% to 1.5%.

[0023] Secondly, the present invention provides a method for preparing the above-mentioned scratch-resistant and easily colored polypropylene composite material, which includes the following steps: mixing the components evenly and then melt-extruding to obtain the scratch-resistant and easily colored polypropylene composite material; wherein, the melt extrusion can be carried out using a twin-screw extruder, the length-to-diameter ratio of the twin-screw extruder is (36~48):1, and the temperature settings of the twin-screw extruder are: zone 1 temperature is 80~120℃, zone 2~5 temperature is 180~200℃, and other zone temperature is 200~230℃.

[0024] Thirdly, this invention provides the application of the above-mentioned scratch-resistant and easily colored polypropylene composite material in the preparation of automotive parts. Specifically, automotive parts refer to bumpers, interior trim parts (instrument panels, door trim panels, seats, steering wheels, etc.), engine peripheral parts (intake manifolds, cooling fans, fan covers, etc.), and electrical components used for wire insulation, battery casings, etc.

[0025] Fourthly, the present invention provides an automotive interior or exterior trim part mainly made of the above-mentioned scratch-resistant and easily colored polypropylene composite material.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] This invention combines small-flake graphite of a specific particle size with large-flake graphite of a specific particle size, with scratch-resistant agent filling the spaces between the flakes. This not only improves the coloring properties of polypropylene composites using small-flake graphite but also facilitates the migration of the scratch-resistant agent to the surface of the polypropylene composite during the migration process. Furthermore, the scratch-resistant agent between the flakes of large-flake graphite can quickly migrate to the surface of the polypropylene composite to form a lubricating layer. In addition, the small-flake graphite can be better dispersed between the large-flake graphite to form a continuous graphite thermally conductive layer, thereby effectively dispersing the heat generated when the polypropylene composite rubs against metal or other sharp hard objects. This significantly improves the scratch resistance of the polypropylene composite while also providing good coloring properties. Detailed Implementation

[0028] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0029] Unless otherwise specified, all other materials, reagents, etc. used in the examples and comparative examples are commercially available.

[0030] 1. Raw materials and reagents

[0031] Polypropylene resin 1: Grade PP EP548R, manufacturer: CNOOC Shell;

[0032] Polypropylene resin 2: Grade PP K9930 (GUANGZHOU), manufacturer: Guangzhou Petrochemical;

[0033] The toughening agent is an ethylene-butene copolymer, brand name POE ENGAGE 7447, manufactured by Dow Chemical.

[0034] The filler is talc powder, brand name TYT-777A, manufactured by Beihai Tianyuan;

[0035] Flake graphite A1, with a mesh count of 1000, grade flake graphite-1000, manufactured by Qingdao Haiheda Graphite Co., Ltd.

[0036] Flake graphite A2, with a mesh size of 2000, grade name flake graphite-2000 mesh, manufactured by Qingdao Xintianhe Carbon Materials Co., Ltd.

[0037] Flake graphite B1, with a mesh size of 325, grade name flake graphite-325 mesh, manufactured by Qingdao Xintianhe Carbon Materials Co., Ltd.

[0038] Flake graphite B2, with a mesh count of 399, grade name flake graphite-399, manufactured by Qingdao Haiheda Graphite Co., Ltd.

[0039] Flake graphite C, with a mesh size of 500, grade flake graphite-500 mesh, manufactured by Qingdao Xintianhe Carbon Materials Co., Ltd.

[0040] Scratch-resistant agent 1 is erucamide, brand name is lubricant-erucamide, and manufacturer is Sichuan Xipuheda;

[0041] Scratch-resistant agent 2 is a silicone masterbatch (composed of carrier resin PP and dimethyl polysiloxane in a mass ratio of 1:1), brand name BZPP301, manufacturer is Chongqing Baozhuan;

[0042] The processing aid is obtained by compounding antioxidant 168, antioxidant 1010 and hindered amine light stabilizer (LA-402AF) in a mass ratio of 1:1:1, wherein antioxidant 168, antioxidant 1010 and hindered amine light stabilizer are all commercially available.

[0043] 2. Examples 1-12 and Comparative Examples 1-5

[0044] Table 1 shows the weight parts of each component in the scratch-resistant and easily colored polypropylene composite materials in Examples 1-12.

[0045]

[0046]

[0047] In Example 4 of Table 1, 4 parts by weight of scratch-resistant agent 2 (i.e., silicone masterbatch) were added, which is equivalent to adding 2 parts by weight of dimethylpolysiloxane.

[0048] The preparation method of the scratch-resistant and easily colored polypropylene composite material in Examples 1 to 12 above includes the following steps: According to the formula, a portion of the scratch-resistant agent (0.2% of the total scratch-resistant agent by mass) is first mixed with flake graphite B and then melt-extruded through a twin-screw extruder. Then, it is mixed evenly with polypropylene resin, toughening agent, filler, flake graphite A, the remaining scratch-resistant agent and processing aid, and then added to a twin-screw extruder for melt extrusion to obtain the scratch-resistant and easily colored polypropylene composite material. The length-to-diameter ratio of the twin-screw extruder is 48:1, and the temperature settings of the twin-screw extruder are: zone 1 temperature is 80-120℃, zone 2 to 5 temperature is 180-200℃, and other zone temperatures are 200-230℃.

[0049] Table 2 shows the weight parts of each component in the scratch-resistant and easily colored polypropylene composites of Comparative Examples 1-4.

[0050]

[0051]

[0052] The preparation method of the scratch-resistant and easily colored polypropylene composite materials in Comparative Examples 1-4 includes the following steps: According to the formula, a portion of the scratch-resistant agent (0.2% by mass of all scratch-resistant agents) is first mixed with flake graphite B and then melt-extruded through a twin-screw extruder. Then, the mixture is uniformly mixed with polypropylene resin, toughening agent, filler, flake graphite A or flake graphite C, the remaining scratch-resistant agent and processing aids, and then added to the twin-screw extruder for melt extrusion to obtain the scratch-resistant and easily colored polypropylene composite material. The length-to-diameter ratio of the twin-screw extruder is 48:1, and the temperature settings of the twin-screw extruder are: Zone 1 temperature is 80-120℃, Zones 2-5 temperature is 180-200℃, and other zones temperature is 200-230℃.

[0053] Comparative Example 5

[0054] This invention provides a comparative example of a scratch-resistant and easily colorable polypropylene composite material. The composition of this polypropylene composite material is essentially the same as that of Example 1 (i.e., 70 parts by weight of polypropylene resin 1, 10 parts by weight of toughening agent, 20 parts by weight of filler, 0.4 parts by weight of flake graphite A1, 0.4 parts by weight of flake graphite B1, 2 parts by weight of scratch-resistant agent, and 0.6 parts by weight of processing aid), the difference being that its preparation method includes the following steps:

[0055] According to the formula, polypropylene resin, toughening agent, filler, flake graphite A, flake graphite B, scratch-resistant agent and processing aid are directly mixed evenly and then added to a twin-screw extruder for melt extrusion to obtain scratch-resistant and easily colored polypropylene composite material. The length-to-diameter ratio of the twin-screw extruder is 48:1, and the temperature settings of the twin-screw extruder are: zone 1 temperature is 80-120℃, zone 2-5 temperature is 180-200℃, and other zone temperature is 200-230℃.

[0056] 3. Performance Testing

[0057] 1) Scratch resistance: The polypropylene composite materials in each example and comparative example were tested on the injection-molded samples using the cross-cut test according to the Volkswagen PV3952-2002 standard. The needle contact load was 10N, the needle diameter was 1mm, and the scratching speed was 1000mm / min. The severity of the scratch was determined by measuring the change in whiteness value L (ΔL) of the sample before and after scratching with a colorimeter. The smaller the ΔL value, the lighter the surface scratch, which indicates that the polypropylene composite material has better scratch resistance.

[0058] 2) Coloring performance: The polypropylene composite materials in each embodiment and comparative example were randomly divided into group A and group B, respectively. The polypropylene composite material in group A was directly injection molded into samples, and the L value (Lcolor) of the samples was measured using a colorimeter. A In Group B, carbon black (1% by mass relative to the polypropylene composite material) was added to the polypropylene composite material, and samples were injection molded. The L value (L) of the samples was then measured using a colorimeter. B ), △L=L B -L A Three sets of ΔL1, ΔL2, and ΔL3 were tested. The coloring performance of the polypropylene composite material was evaluated by the average value of the three sets of ΔL ((ΔL1+ΔL2+ΔL3) / 3). The larger the average value, the better the coloring performance of the polypropylene composite material.

[0059] Table 3. Performance of scratch-resistant and easily colored polypropylene composite materials in each example and comparative example.

[0060] serial number Scratch resistance Coloring properties Example 1 0.43 65.3 Example 2 0.48 64.5 Example 3 0.38 66.4 Example 4 0.41 65.1 Example 5 0.45 65.2 Example 6 0.65 63.2 Example 7 0.56 62.4 Example 8 0.41 63.5 Example 9 0.24 63.1 Example 10 0.73 63.1 Example 11 0.71 63.2 Example 12 0.67 63.5 Comparative Example 1 1.02 56.3 Comparative Example 2 1.34 51.2 Comparative Example 3 0.89 45.5 Comparative Example 4 1.23 40.3 Comparative Example 5 1.03 43.1

[0061] According to the data in Table 3, the whiteness value change ΔL of the polypropylene composites before and after scratching in Examples 1-12 is less than or equal to 0.73, and the average whiteness value change ΔL after coloring is greater than or equal to 62.4. This indicates that the polypropylene composites of the present invention not only have excellent scratch resistance but also good coloring properties. Comparative Examples 1 and 2 show that adding small-particle-size flake graphite A or large-particle-size flake graphite B alone is insufficient to effectively improve the scratch resistance and coloring properties of the polypropylene composites. Furthermore, Comparative Examples 3 and 4 show that while combining flake graphite A with flake graphite C can improve the scratch resistance of the polypropylene composites to some extent, it is difficult to improve its coloring properties. Combining flake graphite B with flake graphite C has extremely limited effect on improving the scratch resistance and coloring properties of the polypropylene composites. This fully demonstrates that only the combination of small-particle-size flake graphite with large-particle-size flake graphite of a specific particle size can effectively improve the scratch resistance and coloring properties of polypropylene composites. Furthermore, according to Comparative Example 5, when flake graphite A, flake graphite B, and scratch-resistant agent are directly mixed with other components and then melt-extruded (at which point the scratch-resistant agent is difficult to fill between the flake structures of flake graphite B due to the presence of other components), the scratch resistance and coloring properties of the polypropylene composite material cannot be significantly improved.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A scratch-resistant and easily colorable polypropylene composite material, characterized in that, By weight, it includes the following components: 50-99 parts polypropylene resin, 0-20 parts toughening agent, 0-25 parts filler, 0.05-1.1 parts flake graphite, and 0.5-4 parts scratch-resistant agent; The flake graphite includes flake graphite A and flake graphite B, wherein the mesh size of flake graphite A is 1000~2000 mesh; the mesh size of flake graphite B is 325~400 mesh, and the flake structure of flake graphite B is filled with a scratch-resistant agent.

2. The scratch-resistant and easily colored polypropylene composite material as described in claim 1, characterized in that, By weight, it includes the following components: 60-80 parts polypropylene resin, 5-15 parts toughening agent, 10-20 parts filler, 0.1-1 parts flake graphite, and 1-3 parts scratch resistant agent.

3. The scratch-resistant and easily colored polypropylene composite material as described in claim 1, characterized in that, The mass ratio of flake graphite A to flake graphite B is 1:(0.3~3).

4. The scratch-resistant and easily colored polypropylene composite material as described in claim 1, characterized in that, The flake graphite B is obtained by melting and extruding a mixture of flake graphite with a mesh size of 325-400 mesh and a scratch-resistant agent.

5. The scratch-resistant and easily colored polypropylene composite material according to any one of claims 1 to 4, characterized in that, At least one of the following must be met: (1) The toughening agent includes at least one of ethylene-octene copolymer, ethylene-butene copolymer, ethylene propylene diene monomer (EPDM) rubber, and ethylene-vinyl acetate copolymer; (2) The filler is at least one of talc, calcium carbonate, mica powder, barium sulfate, and wollastonite; (3) The scratch-resistant agent is at least one of amide-based scratch-resistant agents and organosilicon-based scratch-resistant agents; (4) The components of the scratch-resistant and easily colored polypropylene composite material also include processing aids, which include at least one of antioxidants, heat stabilizers and light stabilizers; (5) It also includes carbon black, wherein the mass fraction of carbon black relative to the scratch-resistant and easily colored polypropylene composite material is 0.5% to 1.5%.

6. The method for preparing the scratch-resistant and easily colored polypropylene composite material according to any one of claims 1 to 4, characterized in that, The process includes the following steps: after mixing the components evenly, the mixture is melt-extruded to obtain a scratch-resistant and easily colored polypropylene composite material.

7. The application of the scratch-resistant and easily colored polypropylene composite material according to any one of claims 1 to 4 in the preparation of automotive parts.

8. An automotive interior or exterior trim part mainly made of the scratch-resistant and easily colored polypropylene composite material as described in any one of claims 1 to 4.

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