Polypropylene composite material as well as preparation method and application thereof

Abstract

The invention discloses a polypropylene composite material as well as a preparation method and application thereof. The polypropylene composite material comprises the following components in parts by weight: 40-80 parts of polypropylene resin; 1 to 6 parts of POE (Polyolefin Elastomer) grafted polysiloxane; 15 to 45 parts of talcum powder; 5 to 15 parts of a toughening agent; 0.1 to 0.5 part of a silane coupling agent; the mass content of the POE chain segment of the POE grafted polysiloxane is 45%-80%. According to the polypropylene composite material disclosed by the invention, by introducing POE grafted polysiloxane and a POE chain segment with a specific grafting ratio, the interfacial energy of a polypropylene phase and polysiloxane can be obviously reduced in thermodynamics, the agglomeration of the polysiloxane phase is fundamentally inhibited, the nanoscale dispersion of the polysiloxane phase is promoted, the two-phase interface is strengthened, and the mechanical property of the polypropylene composite material is improved. Therefore, the high-scratch-resistant polypropylene composite material with low gloss and good mechanical properties is realized.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a polypropylene composite material, its preparation method, and its application. Background Technology

[0002] Polypropylene (PP) is widely used in automotive parts due to its low specific gravity, excellent mechanical properties, low cost, and ease of processing, including decorative and functional components such as dashboards, door panels, and pillars. However, polypropylene has a relatively low surface hardness, making it susceptible to scratches from hard objects during use, resulting in visible scratches that severely affect the aesthetics of interior parts. Adding silicone-based scratch agents has become a common solution in this field to improve the scratch resistance of polypropylene.

[0003] However, in actual production and application, it has been found that existing modified polypropylene materials with added silicone scratch agents have a strong tendency for "self-aggregation" (i.e., entropy-driven phase separation) in the PP matrix because both the silicone scratch agent and the polypropylene matrix are non-polar with low surface energy. This extremely low surface energy difference leads to a high degree of silicone agglomeration within the PP matrix. After simple blending, the silicone phase easily aggregates and is difficult to disperse uniformly, resulting in uneven surface gloss. Localized silicone agglomerations can cause abnormally high gloss, leading to glare under sunlight, interfering with driver visibility and posing a safety hazard. Furthermore, the silicone scratch agent and polypropylene have only very weak van der Waals forces, lacking effective interfacial bonding. Under external forces (scratching, impact), the interface between the silicone agglomerates and the polypropylene matrix easily becomes a stress concentration point, inducing early initiation and development of creasing and cracks, thus deteriorating the material's impact and tensile strength. Therefore, while achieving a certain level of scratch resistance, the material often sacrifices its essential mechanical strength and reliability as a structural component.

[0004] Currently, the industry often uses methods such as increasing processing shear force or simply adjusting the formula to improve the above problems, but the improvement is limited and unstable. Therefore, how to improve the scratch resistance of polypropylene materials while taking into account good appearance and mechanical properties has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention aims to provide a highly scratch-resistant polypropylene composite material that can simultaneously achieve low gloss and good mechanical properties.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a polypropylene composite material, comprising the following components by weight: 40-80 parts of polypropylene resin; POE-grafted polyorganosiloxane 1-6 parts; 15-45 parts talcum powder; 5-15 parts toughening agent; 0.1-0.5 parts of silane coupling agent; The POE-grafted polyorganosiloxane has a POE segment content of 45%-80% by mass.

[0007] The weight parts of the polypropylene resin can be 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts or 80 parts, as well as specific values ​​between the above points.

[0008] Preferably, the polypropylene resin is selected from at least one of homopolymer polypropylene and copolymer polypropylene. More preferably, the melt index of the polypropylene resin at 230°C and 2.16 kg is 8-60 g / 10 min.

[0009] The polypropylene composite material contains 50%-65% polypropylene resin by weight.

[0010] The weight percentage of the POE-grafted polyorganosiloxane can be 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, or 5 parts, as well as specific values ​​between the above-mentioned values.

[0011] Preferably, the POE segment content of the POE-grafted polyorganosiloxane is 50%-75% by mass. The mass content of the POE segment is determined by chemical extraction, and the test method is as follows: accurately weigh the mass of the POE-grafted polyorganosiloxane sample (denoted as m1); reflux the sample in xylene until the soluble matter is completely dissolved, then remove the residual insoluble gel, dry it thoroughly, and weigh it (denoted as m2); calculate the gel content GC (%) = (m2 / m1) × 100%, which is the mass content of the POE segment.

[0012] Preferably, the POE-grafted polyorganosiloxane is prepared by melt reaction of a maleic anhydride-grafted POE copolymer and a hydroxyl-terminated polyorganosiloxane. Further, the maleic anhydride-grafted POE copolymer is a maleic anhydride-grafted ethylene-butene copolymer or a maleic anhydride-grafted ethylene-octene copolymer; the hydroxyl-terminated polyorganosiloxane is selected from hydroxyl-terminated polydimethylsiloxane. Preferably, the number-average molecular weight of the hydroxyl-terminated polydimethylsiloxane is 2000-6000. The number-average molecular weight is determined by gel permeation chromatography.

[0013] This invention provides a method for preparing POE-g-PDMS, comprising the following steps: adding maleic anhydride-grafted POE copolymer and hydroxyl-terminated polyorganosiloxane to a mixer for thorough mixing to obtain a mixture, which is then fed into a twin-screw extruder through the main feed port. The processing temperature is 180~220℃, and the screw speed is 300-500rpm. The mixture is thoroughly sheared, mixed, and reacted by the twin-screw extruder. After extrusion, cooling, and pelletizing, POE-grafted polyorganosiloxane is obtained.

[0014] Preferably, the mass ratio of maleic anhydride-grafted POE copolymer to hydroxyl-terminated polyorganosiloxane is 1:1 to 3:1.

[0015] Preferably, the maleic anhydride grafting rate of the maleic anhydride-grafted POE copolymer is 0.6-1.0%.

[0016] The maleic anhydride grafting rate was determined by chemical titration. The test method is as follows: (1) Maleic anhydride grafted POE copolymer was dissolved in xylene, washed with acetone, and vacuum dried to obtain purified graft material; (2) 0.5g of purified graft material was accurately weighed, 80mL of xylene was added and heated under reflux until fully dissolved, 1.5mL of KOH-ethanol standard solution was added to the pipette, 6mL of isopropanol solution was quickly added, and two drops of phenolphthalein indicator were added. At this time, the solution was dark red; (3) Constant temperature titration was performed using HCl-isopropanol standard solution. The titration was stopped when the paper solution turned pink. The volume of HCl-isopropanol standard solution consumed was recorded as V1; (4) Blank sample titration was performed. 0.5g of non-grafted material was weighed, and steps (2) and (3) were repeated. The volume of HCl-isopropanol standard solution consumed in the blank test was recorded as Vx.

[0017] The formula for calculating the grafting rate is as follows: C MAH %=9.806*(C1V1-C2V X ) / 2m*100%; Among them, C MAH The percentage of maleic anhydride grafting is given. C1 is the concentration of the KOH-ethanol standard solution, C2 is the concentration of the HCl-isopropanol standard solution, and m is the mass of the purified maleic anhydride graft.

[0018] Preferably, the mixing time of the mixer is 3-5 minutes.

[0019] Preferably, the screw of the twin-screw extruder is designed with multiple combinations of anti-thread elements and kneading blocks to provide high-intensity distribution and dispersion mixing, and to establish sufficient back pressure to extend the residence time of the material in the barrel and ensure that the chemical reaction proceeds fully.

[0020] The weight percentage of the talc powder can be 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, or 45 parts, as well as specific values ​​between the above-mentioned values.

[0021] Preferably, the talc powder has a mesh size of 800-5000 mesh.

[0022] The toughening agent can be expressed in parts by weight of 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, as well as specific values ​​between the above-mentioned values.

[0023] Preferably, the toughening agent is selected from polyolefin elastomers. The polyolefin elastomer is preferably at least one of ethylene-butene copolymer and ethylene-octene copolymer; more preferably, the polyolefin elastomer has a melt index of 0.5-15 g / 10 min at 190°C and 2.16 kg.

[0024] The test method for melt flow index described in this invention refers to ISO 1133-1:2022.

[0025] The weight parts of the silane coupling agent can be 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, or 0.5 parts, as well as specific values ​​between the above-mentioned values.

[0026] Preferably, the silane coupling agent is selected from at least one of γ-aminopropyltriethoxysilane (KH550) and γ-glycidoxypropyltrimethoxysilane (KH560).

[0027] Preferably, the weight content of the silane coupling agent in the polypropylene composite material is 0.15%-0.5%. The weight content of the silane coupling agent in the polypropylene composite material can be 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, or specific values ​​between these values.

[0028] Furthermore, the polypropylene composite material, by weight, also includes 0.5-1 parts of processing aids; the processing aids include at least one of antioxidants, weathering agents, and lubricants.

[0029] The antioxidants include, but are not limited to, at least one of antioxidants SONOX 1010, SONOX 168, SONOX 1076, or DLTDP; the weathering agents include, but are not limited to, light stabilizer T-81; and the lubricants include, but are not limited to, at least one of ethyl bis-stearamide (EBS), STRUKTOL TR451, and erucamide. Suitable processing aids may be selected as needed.

[0030] Preferably, the processing aid is a polypropylene masterbatch containing antioxidants, weathering agents, and / or lubricants.

[0031] Secondly, the present invention provides a method for preparing the polypropylene composite material, comprising the following steps: according to the formula, the premix obtained by uniformly mixing all components except talc is fed into a twin-screw extruder from the main feed port, the talc is added through the side feed of the extruder, the length-to-diameter ratio of the extrusion screw is 36-48:1, and the polypropylene composite material is prepared by extrusion granulation after mixing, melting, and homogenization; wherein, the temperature of the twin-screw extruder is set to 80-120℃ in zone 1, 180-200℃ in zones 2-5, and 200-230℃ in other zones.

[0032] Thirdly, the present invention also provides the application of the polypropylene composite material in the preparation of automotive interior parts.

[0033] Fourthly, the present invention provides an automotive interior component, comprising the polypropylene composite material described herein. Specifically, the automotive interior component includes an automotive dashboard, door panel, pillars, etc.

[0034] The present invention has the following beneficial effects: The polypropylene composite material of this invention, by introducing POE grafted with polyorganosiloxane, achieves a significant thermodynamic reduction in the interfacial energy between the polypropylene phase and the polyorganosiloxane through a specific grafting ratio of POE segments. This allows the polyorganosiloxane phase to be stably and uniformly dispersed in the PP matrix as nano / submicron scale microspheres, enhancing interfacial adhesion and effectively eliminating "fisheye" defects and macroscopic phase separation. The extremely fine and uniform polyorganosiloxane dispersion forms a continuous and dense lubricating protective layer on the material surface, greatly improving scratch resistance while reducing surface gloss. Furthermore, the enhanced interfacial adhesion avoids the mechanical property degradation caused by the direct addition of silicone in existing technologies, thus achieving a highly scratch-resistant polypropylene composite material that combines low gloss with good mechanical properties. Detailed Implementation

[0035] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0036] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0037] The materials used in the embodiments and comparative examples of this invention are described below, but are not limited to these materials.

[0038] Polypropylene resin 1: PPH-Y26 (SZ30S), purchased from Sinopec, with a melt index of 25 g / 10 min at 230℃ and 2.16 kg. Polypropylene resin 2: PP EP548R, purchased from CNOOC Shell, with a melt index of 30 g / 10 min at 230℃ and 2.16 kg. POE-grafted polyorganosiloxane 1: Ethylene-butene copolymer grafted with polydimethylsiloxane, the ethylene-butene copolymer segment content is 50% by mass percentage, self-made; POE-grafted polyorganosiloxane 2: Ethylene-butene copolymer grafted with polydimethylsiloxane, the ethylene-butene copolymer segment has a mass percentage content of 63%, self-made; POE-grafted polyorganosiloxane 3: Ethylene-butene copolymer grafted with polydimethylsiloxane, the ethylene-butene copolymer segment content is 75% by mass, self-made; POE-grafted polyorganosiloxane 4: Ethylene-butene copolymer grafted with polydimethylsiloxane, the ethylene-butene copolymer segment content is 30% by mass, self-made; POE-grafted polyorganosiloxane 5: Ethylene-octene copolymer grafted polydimethylsiloxane, with ethylene-octene copolymer segments accounting for 50% by mass percentage, self-made; The preparation method of ethylene-butene copolymer grafted polydimethylsiloxane is as follows: Maleic anhydride-grafted ethylene-butene copolymer (POE TAFMER MH5020, Mitsui Chemicals) and hydroxyl-terminated polydimethylsiloxane (CAS: 70131-67-8, MOK-6600, Merck, Germany, molecular weight 3000) are added to a high-speed mixer at a mass ratio of 1:1 to 3:1 and thoroughly mixed for 3-5 minutes to obtain a mixture. This mixture is then fed into a twin-screw extruder through the main feed port at a processing temperature of 180-220℃ and a screw speed of 300-500 rpm. The twin-screw extruder allows for thorough shearing, mixing, and reaction. After extrusion, cooling, and pelletizing, ethylene-butene copolymer grafted polyorganosiloxane is obtained. The required POE-g-PDMS segment content can be obtained by adjusting the mass ratio of maleic anhydride-grafted ethylene-butene copolymer and hydroxyl-terminated polydimethylsiloxane.

[0039] The preparation method of ethylene-octene copolymer grafted polydimethylsiloxane is as follows: The preparation method of ethylene-octene copolymer-grafted polydimethylsiloxane is as follows: Maleic anhydride-grafted ethylene-octene copolymer (POE TAFMER MA8510, Mitsui Chemicals) and hydroxyl-terminated polydimethylsiloxane (CAS: 70131-67-8, MOK-6600, Merck, Germany, molecular weight 3000) are added to a high-speed mixer at a mass ratio of 1:1 to 3:1 and thoroughly mixed for 3-5 minutes to obtain a mixture. This mixture is then fed into a twin-screw extruder through the main feed port at a processing temperature of 180-220℃ and a screw speed of 300-500 rpm. The twin-screw extruder allows for thorough shearing, mixing, and reaction. After extrusion, cooling, and pelletizing, ethylene-octene copolymer-grafted polyorganosiloxane is obtained. The required ethylene-octene copolymer segment content of POE-g-PDMS can be obtained by adjusting the mass ratio of maleic anhydride-grafted ethylene-octene copolymer and hydroxyl-terminated polydimethylsiloxane.

[0040] Silicone scratching agent: BZPP301, purchased from Chongqing Baozhuan; Talc powder: TYT-777A, 3000 mesh, purchased from Haicheng Tianyuan; Toughening agent 1: POE 7447, Dow Chemical, with a melt index of 4 g / 10min at 190°C and 2.16 kg. Toughening agent 2: POE 7467, Dow Chemical, with a melt index of 1 g / 10min at 190°C and 2.16 kg. Silane coupling agent 1: KH 550, purchased from Nanjing Shuguang Chemical Group Co., Ltd.; Silane coupling agent 2: KH 560, purchased from Guangzhou Shouzheng Chemical Technology Co., Ltd.; Processing aids: Antioxidant 1010, commercially available; the same aids were used in parallel tests.

[0041] Preparation method of polypropylene composite material in the examples and comparative examples: Weigh each component according to the weight parts shown in Table 1 or Table 2, and put all components except talc into a mixer and mix at high speed for 3 minutes to achieve a uniform mixing state. The resulting premix is ​​fed into a twin-screw extruder through the main feed port. Talc is added through the side feed of the extruder. The length-to-diameter ratio of the extrusion screw is 36-48:1. After mixing, melting, homogenization, extrusion and granulation, polypropylene composite material is prepared. The temperature of the twin-screw extruder is set to 80-120℃ in zone 1, 180-200℃ in zones 2-5, and 200-230℃ in other zones.

[0042] Relevant performance testing methods: 1. Notched impact strength: Tested according to standard ISO 180-2019; 2. Tensile strength: Tested according to standard ISO 527-1-2019. 3. Gloss: Using a 200℃ injection molding process and a G125 leather texture mold, the injection molded sample was tested at a 60° angle using a gloss meter.

[0043] 4. Scratch resistance: Adopting the Volkswagen PV3952 test standard, the leather-textured plate is injection molded using G201 leather texture mold. A cross-cut test is performed under a 10N load (the cross-cut size is 40*40mm, the scratching speed V=1000mm / minute, the line spacing is 2mm, and the scratch head diameter is 1mm). The change in color difference value ΔL before and after the cross-cut test is used to evaluate the scratch resistance effect. The larger the ΔL value, the worse the scratch resistance effect.

[0044] Table 1: Distribution ratios (by weight) and performance test results for each group in Examples 1-7

[0045] Table 2: Distribution ratios (by weight) and performance test results of each group in Examples 8-11 and Comparative Examples 1-4

[0046] As can be seen from the above examples and comparative data, the polypropylene composite material of the present invention, by introducing specially designed POE-g-PDMS, significantly reduces the interfacial energy between the polypropylene phase and the silicone phase, fundamentally inhibits the aggregation of the silicone phase, promotes its nanoscale dispersion, and strengthens the interface between the two phases. This results in a high-scratch-resistant polypropylene composite material that combines low gloss with good mechanical properties, with a notched impact strength ≥15 kJ / m². 2 Tensile strength ≥20MPa, gloss ≤3, ΔL ≤1.5.

[0047] In Comparative Example 1, the POE-grafted polyorganosiloxane contained 30% POE segments. The low POE segment content weakened molecular chain movement and reduced POE dispersion, resulting in poor overall POE dispersion and distribution in the composite material. Consequently, the material had high gloss but poor scratch resistance.

[0048] Comparative Example 2 directly used conventional silicone scratch remover, which had a limited effect on improving the scratch resistance of the material and had too high a gloss, failing to meet the requirements for use in automotive interior parts.

[0049] Comparative Example 3, without the addition of silane coupling agent, exhibited high gloss but poor scratch resistance.

[0050] In Comparative Example 4, maleic anhydride-grafted ethylene-butene copolymer and polydimethylsiloxane were directly added to the system to prepare polypropylene composite material. Due to the poor compatibility between polydimethylsiloxane and the polypropylene matrix, the polydimethylsiloxane phase was prone to agglomeration after blending and was difficult to disperse evenly, resulting in uneven surface gloss of the product. In addition, the interfacial adhesion between the polydimethylsiloxane phase and polypropylene was weak. When subjected to external impact or tensile stress, the interface between the silicone agglomerates and the polypropylene matrix was prone to become stress concentration points, leading to a deterioration in the impact strength and tensile strength of the material.

[0051] The above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A polypropylene composite material, characterized in that, By weight, it includes the following components: 40-80 parts of polypropylene resin; POE-grafted polyorganosiloxane 1-6 parts; 15-45 parts talcum powder; 5-15 parts toughening agent; 0.1-0.5 parts of silane coupling agent; The POE-grafted polyorganosiloxane has a POE segment content of 45%-80% by mass.

2. The polypropylene composite material according to claim 1, characterized in that, The POE-grafted polyorganosiloxane contains 50%-75% by mass of POE segments.

3. The polypropylene composite material according to claim 1, characterized in that, The POE-grafted polyorganosiloxane is prepared by melting reaction of maleic anhydride-grafted POE copolymer and hydroxyl-terminated polyorganosiloxane.

4. The polypropylene composite material according to claim 1, characterized in that, The polypropylene resin is selected from at least one of homopolymer polypropylene and copolymer polypropylene; the melt index of the polypropylene resin at 230℃ and 2.16kg is 8-60g / 10min.

5. The polypropylene composite material according to claim 1, characterized in that, The talc powder has a mesh size of 800-5000 mesh.

6. The polypropylene composite material according to claim 1, characterized in that, The toughening agent is selected from polyolefin elastomers; the polyolefin elastomer is selected from at least one of ethylene-butene copolymers and ethylene-octene copolymers; the melt index of the polyolefin elastomer at 190°C and 2.16 kg is 0.5-15 g / 10 min.

7. The polypropylene composite material according to claim 1, characterized in that, The silane coupling agent is selected from at least one of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane.

8. The polypropylene composite material according to claim 1, characterized in that, The product also includes 0.5-1 parts by weight of processing aids; the processing aids include at least one of antioxidants, weathering agents, and lubricants.

9. A method for preparing a polypropylene composite material according to any one of claims 1-8, characterized in that, The process includes the following steps: According to the formula, the premixed material obtained by uniformly mixing all components except talc is fed into a twin-screw extruder through the main feed port. The talc is added through the side feed of the extruder. The length-to-diameter ratio of the extrusion screw is 36-48:

1. After mixing, melting, and homogenizing, the material is extruded and granulated to prepare a polypropylene composite material. The temperature of the twin-screw extruder is set to 80-120℃ in zone 1, 180-200℃ in zones 2-5, and 200-230℃ in other zones.

10. An automotive interior component, characterized in that, Includes the polypropylene composite material according to any one of claims 1-8.

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