Scratch-resistant soft-touch polypropylene composite material, preparation method therefor and use thereof

Abstract

A scratch-resistant soft-touch polypropylene composite material, the scratch-resistant soft-touch polypropylene composite material comprising the following components in parts by weight: 95-105 parts of polypropylene matrix, 10-55 parts of reinforcing filler, 5-25 parts of expanded graphite, 3-10 parts of buckyballs, 5-10 parts of hollow glass microspheres, and 1-5 parts of a coupling agent. The polypropylene composite material has high surface crystallinity, to provide good scratch resistance, and low internal crystallinity, causing the overall polypropylene material have a good soft touch.

Description

Scratch-resistant soft-touch polypropylene composite material and preparation method and application thereof Technical Field

[0001] The present invention belongs to the technical field of engineering plastics, and more specifically, relates to a scratch-resistant soft-touch polypropylene composite material and a preparation method and application thereof. Background Art

[0002] Polypropylene is widely used in automobiles due to its low density, high cost-effectiveness, excellent heat resistance, rigidity, chemical resistance, ease of processing, molding, and recycling, making it the most widely used and fastest-growing automotive plastic. The rapid development of the automotive industry in recent years has placed increasingly stringent requirements on interior and exterior materials. For example, instrument panels, door panels, and bumpers require high strength, impact resistance, scratch resistance, dimensional stability, and a soft touch.

[0003] Automotive interior materials are typically required to have a soft touch (generally with a Rockwell hardness of no more than 40 HRB), but common polyolefin (polypropylene) materials have a high hardness and lack the leather-like softness. Currently, the main method for achieving a soft touch is to reduce the hardness by adding a large amount of elastomer (rubber) to the polyolefin component. Furthermore, the scratch resistance of polyolefin materials is also a key performance characteristic. Poor scratch resistance can significantly affect the appearance of the product, a crucial property for automotive exterior parts, vehicles such as ATVs (all-terrain vehicles), durable goods, and furniture. Therefore, polypropylene's soft touch and scratch resistance have, to a certain extent, limited its widespread application in automotive interior products.

[0004] At present, domestic and foreign scholars have done a lot of research on the scratch resistance of polypropylene substrates, which generally include the following aspects: (1) coating a scratch-resistant protective coating on the surface of the polypropylene substrate. (2) modifying the scratch resistance of the polymer by blending different polymers. The improvement effect of this method is not obvious. (3) reducing the surface friction coefficient of the polypropylene substrate by adding a scratch-resistant agent or auxiliary agent, thereby improving the scratch resistance of the polypropylene substrate. Patent CN109836699A discloses a graphene-modified polypropylene scratch-resistant material and its preparation method. Graphene is added to the polypropylene material. Graphene has good dispersibility and can effectively improve the scratch resistance of polypropylene while maintaining the strength of the polypropylene material, so that the surface of the material has excellent scratch resistance and wear resistance during actual use. However, the graphene used in this scheme also acts as a polypropylene nucleating agent to a certain extent, increasing the crystallinity of polypropylene, thereby increasing the surface hardness of the polypropylene material, making its soft touch poor.

[0005] Therefore, how to provide a polypropylene composite material with both excellent soft touch and scratch resistance has become a technical problem that needs to be solved urgently. Summary of the Invention

[0006] In response to the above-mentioned existing technical problems, the primary purpose of the present invention is to provide a scratch-resistant soft-touch polypropylene composite material. The polypropylene composite material has a high degree of crystallinity in the surface layer, which can provide excellent scratch resistance; the internal degree of crystallinity is relatively low, which retains good softness, so that the polypropylene composite material as a whole has good soft touch and scratch resistance.

[0007] The second object of the present invention is to provide a method for preparing the scratch-resistant soft-touch polypropylene composite material.

[0008] The third object of the present invention is to provide a use of a scratch-resistant soft-touch polypropylene composite material in the preparation of automotive parts.

[0009] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0010] A scratch-resistant soft-touch polypropylene composite material comprises the following components, measured by weight: 95-105 parts of a polypropylene matrix, 10-55 parts of a reinforcing filler, 5-25 parts of expanded graphite, 3-10 parts of octylene, 5-10 parts of hollow glass microspheres, and 1-5 parts of a coupling agent.

[0011] The present invention adds expanded graphite, spherical graphene, hollow glass microspheres and a coupling agent to a polypropylene matrix. Under the combined action of the four raw materials, the obtained polypropylene composite material has high surface crystallinity, which, combined with the strength of the hollow glass microspheres, can provide excellent scratch resistance. Meanwhile, the interior of the polypropylene composite material has low crystallinity, ensuring that the polypropylene composite material as a whole has excellent softness (i.e., soft touch).

[0012] Specifically, on the one hand, in polypropylene composite material of the present invention, footballene and expanded graphite are made up of carbon element, under the interaction of carbon atoms, footballene can be embedded in the porous structure of expanded graphite and move, and the rolling of footballene of spherical structure in expanded graphite causes the expanded graphite being dispersed in polypropylene inside to not play the effect of polypropylene nucleator well, therefore, the crystallinity of the polypropylene composite material inside of final preparation is lower, has retained excellent pliability.On the other hand, footballene, in the process of embedding expanded graphite pore structure, inevitably can peel off the lamella structure of expanded graphite, peel off part layered graphene sheet, these graphene lamellae structures are lightweight, have stronger migration ability, under the drive of hollow glass microspheres, (the density of hollow glass microspheres is low, easily migrates to material surface and provides surface strength in polypropylene), along with hollow glass microspheres, migrate to polypropylene material surface together.In polypropylene material surface, layered graphene has served as polypropylene nucleator, thereby improved the surface crystallinity of polypropylene composite material, further improved surface rigidity, made polypropylene composite material surface have good scratch resistance. Furthermore, the sphericalene and hollow glass microspheres in the present invention can also act as dispersants, dispersing the expanded graphite. The coupling agent in the polypropylene system can also improve the compatibility of inorganic fillers such as hollow glass microspheres, expanded graphite, and sphericalene with the polypropylene matrix to a certain extent, enhancing their dispersibility in the polypropylene.

[0013] The present invention not only significantly improves the scratch resistance of the polypropylene composite material, but also improves the softness of the polypropylene composite material through the combined action of the above four substances and in combination with other components in the system.

[0014] Preferably, the melt flow rate of the polypropylene matrix at 230°C and 2.16 kg is 10 to 65 g / 10 min. Further preferably, the melt flow rate of the polypropylene matrix at 230°C and 2.16 kg is 10 to 35 g / 10 min. When the melt flow rate of the polypropylene matrix is ​​within this range, the polypropylene composite material system has good fluidity, which is conducive to uniform mixing of the raw material components, and can produce a polypropylene composite material with excellent comprehensive mechanical strength and flexibility. The melt flow rate (MFR) of the polypropylene is measured according to the standard method of "ISO 1133-1:2011".

[0015] The melt flow rate of the polypropylene matrix described in the present application can be 10g / 10min, 15g / 10min, 20g / 10min, 25g / 10min, 30g / 10min, 35g / 10min, etc., or an interval range formed by any of the above values, such as 10-20g / 10min, 25-35g / 10min, etc., but the present invention is not limited thereto.

[0016] Specifically, in the present application, the mass percentage of the polypropylene matrix in the scratch-resistant soft-touch polypropylene composite material is not less than 52%.

[0017] Preferably, the polypropylene matrix can be selected from one or more of homopolymer polypropylene, random copolymer polypropylene, and block copolymer polypropylene.

[0018] Further preferably, the polypropylene matrix is ​​block copolymer polypropylene.

[0019] Preferably, the reinforcing filler is selected from one or more of glass fiber, calcium carbonate, talc, wollastonite and mica.

[0020] Preferably, the particle size range of the expanded graphite is 30 to 100 mesh. Further preferably, the particle size range of the expanded graphite is 32 to 50 mesh. Expanded graphite is a substance with a worm-like loose porous structure obtained by intercalation, water washing, drying, and high-temperature expansion of natural graphite flakes. Expanded graphite in this specific particle size range can ensure that footballene enters the porous structure of the expanded graphite and can maintain a certain degree of mobility. The particle size range of the expanded graphite described in this application can be 32 mesh, 35 mesh, 38 mesh, 41 mesh, 44 mesh, 47 mesh, 50 mesh, etc., or an interval range formed by any of the above values, such as 32 to 35 mesh, 32 to 38 mesh, etc., but the present invention is not limited thereto.

[0021] Preferably, the particle size range of the hollow glass microspheres is 800-5000 mesh. Further preferably, the particle size range of the hollow glass microspheres is 1000-3000 mesh. In the present application, the particle size range of the hollow glass microspheres can be 1000 mesh, 1500 mesh, 2000 mesh, 2500 mesh, 3000 mesh, etc., or an interval range formed by any of the above values, such as 1000-1500 mesh, 1000-2000 mesh, etc., but the present invention is not limited thereto.

[0022] Preferably, the true density of the hollow glass microspheres is 0.15 to 0.60 g / cm 3 More preferably, the true density of the hollow glass microspheres is 0.20 to 0.40 g / cm 3 The test method for the hollow glass microspheres is ISO 1183-1-2019.

[0023] Preferably, the coupling agent is a silane coupling agent. Further preferably, the silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane.

[0024] Preferably, the scratch-resistant soft-touch polypropylene composite material further comprises 1 to 10 parts of an auxiliary agent. Such auxiliary agents include, but are not limited to, flame retardants, antioxidants, and antistatic agents. Conventional flame retardants, antioxidants, and antistatic agents in the art can be used in the present invention.

[0025] Furthermore, the present invention also seeks to protect a method for preparing a scratch-resistant soft-touch polypropylene composite material, which comprises mixing a polypropylene matrix, reinforcing filler, expanded graphite, ethylene oxide, hollow glass microspheres and a coupling agent, and melt-extruding the mixture to prepare the scratch-resistant soft-touch polypropylene composite material.

[0026] Preferably, the temperature of the melt extrusion is 170-210°C.

[0027] Preferably, the screw speed during the melt extrusion is 400-600 rpm.

[0028] Furthermore, the present invention also claims protection for the use of the aforementioned scratch-resistant, soft-touch polypropylene composite material in the manufacture of automotive parts. Specifically, the scratch-resistant, soft-touch polypropylene composite material can be used as an interior or exterior material in applications such as instrument panels, door panels, and bumpers. This is particularly true in applications where high scratch resistance and a soft touch are required.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention adds expanded graphite, spherical graphene, hollow glass microspheres, and a coupling agent to polypropylene. The combined effects of these four substances create a polypropylene composite material with high surface crystallinity. Combined with the strength of the hollow glass microspheres, this provides excellent scratch resistance. Meanwhile, the internal crystallinity of the polypropylene composite is relatively low, ensuring an overall soft touch. The polypropylene composite material provided by the present invention combines excellent scratch resistance with a soft touch. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to the accompanying drawings and specific examples, but the examples do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0032] Description of raw materials for embodiments and comparative examples:

[0033] Polypropylene matrix:

[0034] PP-1: block copolymer polypropylene, MFR = 10 g / 10 min at 230 ° C and 2.16 kg load, BX3500, purchased from Korea Aiskai;

[0035] PP-2: block copolymer polypropylene, MFR = 30 g / 10 min at 230 ° C and 2.16 kg load, BX3800, purchased from Korea Aiskai;

[0036] PP-3: homopolymer polypropylene, MFR = 30 g / 10 min at 230 °C and 2.16 kg load, SZ30S, purchased from Sino-Korean Petrochemical (Wuhan);

[0037] PP-4: random copolymer polypropylene, MFR = 2.5 g / 10 min at 230 ° C and 2.16 kg load, SM198, purchased from Malaysia Datang;

[0038] PP-5: block copolymer polypropylene, MFR=60 g / 10 min at 230°C and 2.16 kg load, BX3900, purchased from Aiskai, Korea.

[0039] Expanded graphite (expanded graphite 1), particle size 32 mesh, brand EG200, Shandong Shuangyu Carbon Co., Ltd.

[0040] Expanded graphite (expanded graphite 2), particle size 50 mesh, brand EG250, Shandong Shuangyu Carbon Co., Ltd.

[0041] Expanded graphite (expanded graphite 3), particle size 80 mesh, brand EG300, Shandong Shuangyu Carbon Co., Ltd.

[0042] Expanded graphite (expanded graphite 4), particle size 100 mesh, brand EG350, Shandong Shuangyu Carbon Co., Ltd.

[0043] Graphene, brand - industrial grade graphene oxide, Suzhou Tanfeng Graphene Technology Co., Ltd.

[0044] Hollow glass microspheres (hollow glass microspheres 1), true density 0.40 g / cm 3 , particle size is 1250 mesh, Shanghai Gerunya Nanomaterials Co., Ltd.

[0045] Hollow glass microspheres (hollow glass microspheres 2), true density 0.20 g / cm 3 , particle size is 2500 mesh, Shanghai Gerunya Nanomaterials Co., Ltd.

[0046] Hollow glass microspheres (hollow glass microspheres 3), true density 0.60g / cm 3 , particle size is 800 mesh, Shanghai Gerunya Nanomaterials Co., Ltd.

[0047] Hollow glass microspheres (hollow glass microspheres 4), true density 0.15g / cm 3 , particle size is 5000 mesh, Shanghai Gerunya Nanomaterials Co., Ltd.

[0048] Soccerene, Fullerene C60, Hubei Weishi Chemical Reagent Co., Ltd.

[0049] Coupling agent, γ-aminopropyltriethoxysilane, KH550, commercially available.

[0050] Cage oligomeric silsesquioxane (POSS), octamethyl-POSS (octamethyl caged polysilsesquioxane), commercially available.

[0051] Scratch resistant agent, nano-silicon oxide, commercially available.

[0052] Reinforcing filler, glass fiber, commercially available.

[0053] Unless otherwise specified, the components (eg, coupling agents, reinforcing fillers, etc.) used in the parallel examples and comparative examples are all the same commercially available products.

[0054] Example 1

[0055] The weight parts of the raw materials used in Example 1 are shown in Table 1.

[0056] A method for preparing a scratch-resistant soft-touch polypropylene composite material, comprising the following steps:

[0057] The polypropylene matrix, reinforcing filler, expanded graphite, ethylene glycol, hollow glass microspheres and coupling agent were weighed and mixed according to the weight parts in Table 1, and then melt-extruded at a speed of 400-600 r / min in a 75D co-rotating twin-screw extruder at 170-210° C. (the temperature of the twin-screw extruder from the feeding section to the die was 170° C., 200° C., 210° C., 210° C., 205° C., 205° C., 200° C., and 200° C., in sequence) and granulated to obtain a scratch-resistant soft-touch polypropylene composite material.

[0058] Examples 2 to 15

[0059] The weight parts of the raw materials used in the following examples are shown in Table 1.

[0060] The specific preparation steps of the following examples are the same as those of Example 1.

[0061] Comparative Examples 1 to 7

[0062] The weight parts of the raw materials used in the following comparative examples are shown in Table 2.

[0063] The specific preparation steps of each comparative example are the same as those of Example 1.

[0064] Table 1 is the formula components of each embodiment:

[0065] Table 1

[0066] Table 2 shows the formula components of each comparative example:

[0067] Table 2

[0068] The scratch-resistant soft-touch polypropylene composite materials prepared in the above examples and comparative examples were tested according to the following test methods:

[0069] 1. Scratch resistance (△L): Tested in accordance with Volkswagen's PV3952-2019-03 standard, using a 10N load and Ford STUCCO textured plate. The smaller the △L value, the better the scratch resistance.

[0070] 2. Soft Touch (Rockwell Hardness): Measured using a Rockwell hardness tester, using a 100kg load and a 58mm diameter hardened steel ball, the hardness is expressed in HRB. The lower the Rockwell hardness, the better the soft touch.

[0071] Table 3 and Table 4 are the performance test results of each embodiment and comparative example respectively.

[0072] Table 3

[0073] Table 4

[0074] The data from Examples 1 to 15 demonstrate that the addition of expanded graphite, sphericalene, hollow glass microspheres, and a coupling agent to polypropylene results in a polypropylene composite material exhibiting both excellent scratch resistance and a soft touch. The polypropylene composite materials exhibited a scratch resistance ΔL of less than 0.2, and a Rockwell hardness (measured as a soft touch) of less than 35. Furthermore, the polypropylene composite materials exhibited a scratch resistance ΔL of less than 0.1, and a Rockwell hardness (measured as a soft touch) of less than 32.

[0075] The results of Example 1, Example 2 and Example 5 show that as the melt mass flow rate increases, the fluidity of the matrix increases during the preparation process, and the overall crystallinity of the polypropylene material decreases, which is conducive to improving the softness; while the scratch resistance of the surface layer shows a trend of first increasing and then decreasing.

[0076] The results of Example 1, Examples 6 to 8, Comparative Example 1, and Comparative Example 6 show that the addition of footballene significantly improves the soft touch and scratch resistance of the polypropylene material. As the particle size of the expanded graphite decreases, the proportion of single-layer graphene peeled off from the expanded graphite under the action of footballene decreases, which in turn leads to a downward trend in the wear resistance of the surface of the obtained polypropylene material.

[0077] The results of Examples 1 and 9-11 show that as the hollow glass microspheres increase in size, their floating ability in the system deteriorates, leading to a downward trend in the friction resistance of the surface layer. When the hollow glass microspheres are within a specific particle size range, they can disperse to a certain extent within the polypropylene material, reducing the crystallinity of the polypropylene to a certain extent and improving the soft touch. Therefore, within this appropriate range, the hollow glass microspheres can achieve both the scratch resistance and soft touch of the polypropylene material.

[0078] In Comparative Example 1, no footballene was added, and the internal flexibility of the obtained polypropylene material was poor; in Comparative Example 2, no hollow glass microspheres were added, and the scratch resistance of the obtained polypropylene surface was significantly deteriorated; in Comparative Example 3, no expanded graphene was added, and the scratch resistance of the obtained polypropylene material was significantly deteriorated; in Comparative Example 4, no silane coupling agent was added, the migration ability of the hollow glass microspheres was deteriorated, and the scratch resistance of the polypropylene surface could not meet the use requirements.

[0079] In Comparative Example 5, expanded graphite is replaced with layered graphene. Layered graphene increases the crystallinity inside the polypropylene material, resulting in poor flexibility of the polypropylene material. In Comparative Example 6, footballene is replaced with POSS, which also has a cage structure. POSS has poor compatibility with expanded graphite, and the resulting polypropylene material has poor internal flexibility. In Comparative Example 7, expanded graphite and footballene are replaced with ordinary scratch-resistant agents, and the flexibility of the resulting polypropylene material is significantly deteriorated.

[0080] The foregoing examples are merely illustrative, serving to illustrate some of the features of the method of the present invention. The appended claims are intended to claim the widest possible scope that can be envisioned, and the embodiments presented herein are demonstrated by the applicant's actual experimental results. Therefore, the applicant intends that the appended claims are not limited by the selection of examples illustrating the features of the present invention. Some numerical ranges used in the claims also include subranges therein, and variations in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A scratch-resistant soft-touch polypropylene composite material, characterized in that: The invention comprises the following components by weight: 95-105 parts of polypropylene matrix, 10-55 parts of reinforcing filler, 5-25 parts of expanded graphite, 3-10 parts of ethylene, 5-10 parts of hollow glass microspheres and 1-5 parts of coupling agent.

2. The scratch-resistant soft-touch polypropylene composite material according to claim 1, characterized in that: The melt flow rate of the polypropylene matrix at 230° C. and 2.16 kg is 10 to 65 g / 10 min.

3. The scratch-resistant soft-touch polypropylene composite material according to claim 1, characterized in that: The polypropylene matrix is ​​selected from one or more of homopolymer polypropylene, random copolymer polypropylene and block copolymer polypropylene.

4. The scratch-resistant soft-touch polypropylene composite material according to claim 3, characterized in that: The polypropylene matrix is ​​block copolymer polypropylene.

5. The scratch-resistant soft-touch polypropylene composite material according to claim 1, characterized in that: The reinforcing filler is selected from one or more of glass fiber, calcium carbonate, talc, wollastonite and mica.

6. The scratch-resistant soft-touch polypropylene composite material according to claim 1, characterized in that: The particle size of the expanded graphite ranges from 30 to 100 meshes.

7. The scratch-resistant soft-touch polypropylene composite material according to claim 1, characterized in that: The particle size of the hollow glass microspheres ranges from 800 to 5000 meshes.

8. The scratch-resistant soft-touch polypropylene composite material according to claim 1, characterized in that: The coupling agent is a silane coupling agent.

9. The method for preparing the scratch-resistant soft-touch polypropylene composite material according to any one of claims 1 to 8, characterized in that: The polypropylene matrix, reinforcing filler, expanded graphite, ethylene oxide, hollow glass microspheres and a coupling agent are mixed and melt-extruded to prepare the scratch-resistant soft-touch polypropylene composite material.

10. Use of the scratch-resistant soft-touch polypropylene composite material according to any one of claims 1 to 8 in the preparation of automobile parts.

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