Low-gloss polypropylene composite material and method for producing the same

Abstract

This invention belongs to the field of polymer materials technology, specifically relating to a low-gloss polypropylene composite material and its preparation method. The low-gloss polypropylene composite material is prepared from the following components in parts by weight: 53.4-89.3 parts polypropylene, 5-30 parts inorganic filler, 2-10 parts POE, 3-5 parts ultra-high molecular weight polyethylene, 0.2-0.6 parts nucleating agent, 0.2-0.4 parts antioxidant, and 0.3-0.6 parts processing aid. This invention improves the melt strength of the material by adding ultra-high molecular weight PE, and simultaneously increases the crystallization rate by adding alkyl carboxylate nucleating agents, thereby preventing the later-stage surface texture "collapse" and better replicating the texture depth and pattern, thus further reducing the product's gloss.

Description

Technical Field

[0001] This invention belongs to the field of polymer technology, specifically designing a low-gloss polypropylene composite material and its preparation method. Background Technology

[0002] Polypropylene (PP), as a thermoplastic, plays a crucial role in the automotive industry, particularly in the manufacture of automotive interior materials, due to its excellent balance of rigidity and toughness, good processability, light weight, and relatively low cost. It not only meets the strength, durability, and safety requirements of automotive interior components but also facilitates various processing methods such as injection molding, extrusion, or thermoforming, thereby optimizing production efficiency and cost control.

[0003] Currently, polypropylene is widely used in automotive interior components such as dashboards, center consoles, door panels, and pillars. However, because these components occupy a significant portion of the driver's field of vision, parts made of traditional polypropylene have a high gloss finish, giving them a noticeably cheap, plastic look. Furthermore, the high-gloss surface treatment not only affects the overall aesthetics of the interior but can also reflect light, interfering with the driver's vision and impacting driving safety. Therefore, in high-end models, leather upholstery is typically used for interior materials. This involves covering the surface of a polypropylene substrate with a layer of leather, fabric, or other synthetic materials to improve the feel, reduce gloss, and enhance the overall interior's perceived quality. However, the leather upholstery process is complex and expensive, and involves adhesive processes, leading to the risk of releasing volatile organic compounds (VOCs) due to the use of adhesives and other chemicals, potentially impacting in-vehicle air quality. Therefore, the development of low-gloss polypropylene materials is particularly urgent. Summary of the Invention

[0004] The purpose of this invention is to provide a low-gloss polypropylene composite material and its preparation method.

[0005] A low-gloss polypropylene composite material is prepared from the following components in parts by weight: 53.4-89.3 parts polypropylene, 5-30 parts inorganic filler, 2-10 parts POE, 3-5 parts ultra-high molecular weight polyethylene, 0.2-0.6 parts nucleating agent, 0.2-0.4 parts antioxidant, and 0.3-0.6 parts processing aid.

[0006] In a further embodiment, the polypropylene is a copolymer polypropylene.

[0007] In a further embodiment, the inorganic filler is any one of talc, calcium carbonate, barium sulfate, wollastonite, and whiskers.

[0008] In a further embodiment, the POE is an ethylene-octene copolymer or an ethylene-butene copolymer.

[0009] In a further embodiment, the ultra-high molecular weight polyethylene is an unbranched linear polyethylene with a molecular weight of 1.5 million or more.

[0010] In a further embodiment, the nucleating agent is an alkyl carboxylate nucleating agent.

[0011] In a further embodiment, the antioxidant is one or a combination of two of the following: phosphite antioxidants or hindered phenolic antioxidants.

[0012] In a further embodiment, the processing aid is calcium stearate or zinc stearate.

[0013] The second objective of this invention is to provide a method for preparing the aforementioned low-gloss polypropylene composite material, comprising the following steps:

[0014] After mixing 53.4-89.3 parts of polypropylene, 5-30 parts of inorganic filler, 2-10 parts of POE, 3-5 parts of high-molecular-weight polyethylene, 0.2-0.6 parts of nucleating agent, 0.2-0.4 parts of antioxidant, and 0.3-0.6 parts of processing aid evenly, the mixture is fed into a twin-screw extruder through the main feed port. The polypropylene composite material is obtained through extrusion, stranding, and granulation.

[0015] This invention is the first to propose simultaneously adding ultra-high molecular weight polyethylene and alkyl carboxylate nucleating agents to modified plastics. Combined with the use of POE, this achieves a lower material gloss. The low-gloss modified polypropylene material prepared by this invention can be used in automotive interiors and home appliance components. It requires no painting or wrapping; simply using a standard textured mold is sufficient to achieve a lower gloss, enhancing its texture and avoiding post-processing.

[0016] In this invention, POE is added. Since POE and PP have different compatibility, a fine phase separation will be formed at the phase interface. Furthermore, due to the presence of POE, the surface hardness of the material is low. During the process of material crystallization and shrinkage, the surface will have a microscopic uneven structure, which can produce diffuse reflection, thereby reducing the material's reflection of light.

[0017] This invention incorporates both ultra-high molecular weight polyethylene (UHMWPE) and alkyl carboxylate nucleating agents. On one hand, UHMWPE improves the melt strength of the matrix resin; on the other hand, the alkyl carboxylate nucleating agent significantly accelerates the crystallization rate of polypropylene. Furthermore, the lattice-matching relationship between the alkyl carboxylate nucleating agent and polypropylene allows polypropylene molecular chains to arrange and stack orderly on the nucleating agent surface, forming a regular crystal structure. This significantly reduces the gloss of polypropylene products, making them more suitable for low-gloss materials.

[0018] Furthermore, low-gloss products are typically manufactured using a mold-based textured process. However, different materials exhibit significant differences in their ability to replicate textures, primarily influenced by their physical and chemical properties. Especially after mold opening, the depth and shape of the texture may change due to material shrinkage and crystallization during the cooling and solidification process. The shrinkage during cooling can cause the texture depth to collapse, resulting in a reduction in texture depth. Simultaneously, stress concentration at texture corners can lead to springback, rounding off sharp corners and blurring the overall texture outline, thus increasing gloss. This invention addresses this issue by adding ultra-high molecular weight polyethylene (UHMWPE) to increase melt strength and alkyl carboxylates as nucleating agents to accelerate crystallization. This prevents the subsequent "collapse" of the surface texture, allowing for better replication of texture depth and patterns, thereby further reducing the product's gloss. Detailed Implementation

[0019] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough and complete understanding of the disclosure of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0021] The alkyl carboxylate nucleating agents in this invention include malonate, glutarate, adipate, heptahydrate, octanoate, etc., as well as alkyl carboxylates with special structures, such as bicyclic [2,2,1]heptane dicarboxylate (HPN-68) and bicyclic [2,2,1]-5-heptene-2,3-dicarboxylate. To facilitate the measurement of the final polypropylene composite material, bicyclic [2,2,1]heptane dicarboxylate (HPN-68) is used as the alkyl carboxylate nucleating agent in all the following examples.

[0022] Polypropylene YPJ1215C (Yangzi Petrochemical), K7227H (Wuhan Ethylene), K9026 (Yanshan Petrochemical), BX3800 (SK Chemicals, South Korea);

[0023] Inorganic fillers: Talc AH51105 (Liaoning Aihai), Barium Sulfate BSM-M30 (Guangdong Jimei), Calcium Carbonate LD-1000C (Lida Supermicro), Wollastonite 1512 (Shandong Gaotai Chemical Technology), Basic Magnesium Sulfate Whiskers WS-1S2 (Yingkou Wesker Chemical Co., Ltd.);

[0024] POE is ethylene-octene copolymer 8842, 8180, 8200 (Dow Chemical) or ethylene-butene copolymer P4000 (Dow Chemical);

[0025] Ultra-high molecular weight polyethylene (UHMWPE) is selected from unbranched linear polyethylene with a molecular weight of 1.5 million or more, such as UHM (Lyander Basel) and GUR4050 (Celanis).

[0026] For phosphite antioxidants, antioxidant 168 is selected; for hindered phenolic antioxidants, antioxidant 1010 is selected.

[0027] Example 1:

[0028] 75 parts of polypropylene YPJ1215C, 15 parts of inorganic filler talc, 5 parts of POE (ethylene-octene copolymer 8842), 4 parts of ultra-high molecular weight polyethylene UHM, 0.4 parts of alkyl carboxylate nucleating agent, 0.1 parts of phosphite antioxidant, 0.2 parts of hindered phenolic antioxidant, and 0.3 parts of processing aid calcium stearate were mixed evenly and fed into a twin-screw extruder through the main feed port. The polypropylene composite material was obtained by extrusion, stranding, and granulation.

[0029] The temperatures of the twin-screw extruder from the feed inlet to the die are as follows: Zone 1 190℃, Zone 2 190℃, Zone 3 200℃, Zone 4 200℃, Zone 5 210℃, Zone 6 210℃, Zone 7 210℃, Zone 8 210℃, and Zone 9 210℃. The side feed inlet is located in Zone 8, and the screw speed is 400 r / min.

[0030] Example 2:

[0031] 66.9 parts of polypropylene K9026, 20 parts of inorganic filler calcium carbonate, 8 parts of POE (ethylene-butene copolymer P4000), 4 parts of high-molecular-weight polyethylene GUR4050, 0.3 parts of alkyl carboxylate nucleating agent, 0.2 parts of phosphite antioxidant, 0.2 parts of hindered phenolic antioxidant, and 0.4 parts of processing aid zinc stearate were mixed evenly and fed into a twin-screw extruder through the main feed port. The polypropylene composite material was obtained by extrusion, stranding, and granulation.

[0032] The temperatures of the twin-screw extruder from the feed inlet to the die are as follows: Zone 1 200℃, Zone 2 200℃, Zone 3 200℃, Zone 4 220℃, Zone 5 210℃, Zone 6 210℃, Zone 7 210℃, Zone 8 220℃, and Zone 9 210℃. The side feed inlet is located in Zone 8, and the screw speed is 400 r / min.

[0033] Example 3:

[0034] 62.7 parts of polypropylene K7227H, 20 parts of inorganic wollastonite, 6 parts of POE (ethylene-octene copolymer 8180), 5 parts of ultra-high molecular weight polyethylene UHM, 0.5 parts of alkyl carboxylate nucleating agent, 0.3 parts of hindered phenolic antioxidant, and 0.5 parts of processing aid zinc stearate were mixed evenly and then fed into a twin-screw extruder through the main feed port. The polypropylene composite material was obtained by extrusion, stranding, and granulation.

[0035] The temperatures of the twin-screw extruder from the feed inlet to the die are as follows: Zone 1 200℃, Zone 2 210℃, Zone 3 220℃, Zone 4 220℃, Zone 5 220℃, Zone 6 220℃, Zone 7 230℃, Zone 8 230℃, and Zone 9 220℃. The side feed inlet is located in Zone 8, and the screw speed is 400 r / min.

[0036] Example 4:

[0037] 89.3 parts of polypropylene BX3800, 2 parts of POE 8200, 5 parts of inorganic filler basic magnesium sulfate whiskers, 3 parts of ultra-high molecular weight polyethylene UHM, 0.2 parts of alkyl carboxylate nucleating agent, 0.2 parts of phosphite antioxidant, and 0.3 parts of processing aid calcium stearate were mixed evenly and then fed into a twin-screw extruder through the main feed port. The polypropylene composite material was obtained by extrusion, stranding, and granulation.

[0038] The temperatures of the twin-screw extruder from the feed inlet to the die are as follows: Zone 1 200℃, Zone 2 200℃, Zone 3 210℃, Zone 4 210℃, Zone 5 220℃, Zone 6 230℃, Zone 7 230℃, Zone 8 230℃, and Zone 9 210℃. The side feed inlet is located in Zone 8, and the screw speed is 400 r / min.

[0039] Example 5:

[0040] 53.4 parts of polypropylene YPJ1215C, 10 parts of inorganic filler barium sulfate, 10 parts of POE (ethylene-octene copolymer 8200), 5 parts of ultra-high molecular weight polyethylene GUR4050, 0.6 parts of alkyl carboxylate nucleating agent, 0.2 parts of phosphite antioxidant, 0.2 parts of hindered phenolic antioxidant, and 0.6 parts of processing aid calcium stearate were mixed evenly and fed into a twin-screw extruder through the main feed port. The polypropylene composite material was obtained by extrusion, stranding, and granulation.

[0041] The temperatures of the twin-screw extruder from the feed inlet to the die are as follows: Zone 1 190℃, Zone 2 190℃, Zone 3 200℃, Zone 4 200℃, Zone 5 200℃, Zone 6 210℃, Zone 7 210℃, Zone 8 210℃, and Zone 9 210℃. The side feed inlet is located in Zone 8, and the screw speed is 400 r / min.

[0042] Comparative Example 1:

[0043] 79 parts of polypropylene YPJ1215C, 15 parts of inorganic filler talc, 5 parts of POE (ethylene-octene copolymer 8842), 0.4 parts of alkyl carboxylate nucleating agent, 0.1 parts of phosphite antioxidant, 0.2 parts of hindered phenolic antioxidant, and 0.3 parts of processing aid calcium stearate were mixed evenly and fed into a twin-screw extruder through the main feed port. The polypropylene composite material was obtained by extrusion, stranding, and granulation.

[0044] The temperatures of the twin-screw extruder from the feed inlet to the die are as follows: Zone 1 190℃, Zone 2 190℃, Zone 3 200℃, Zone 4 200℃, Zone 5 210℃, Zone 6 210℃, Zone 7 210℃, Zone 8 210℃, and Zone 9 210℃. The side feed inlet is located in Zone 8, and the screw speed is 400 r / min. Comparative Example 2:

[0045] 75.4 parts of polypropylene YPJ1215C, 15 parts of inorganic filler talc, 5 parts of POE (ethylene-octene copolymer 8842), 4 parts of high ultramolecular polyethylene UHM, 0.1 parts of phosphite antioxidant, 0.2 parts of hindered phenolic antioxidant, and 0.3 parts of processing aid calcium stearate were mixed evenly and then fed into a twin-screw extruder through the main feed port. The polypropylene composite material was obtained by extrusion, stranding, and granulation.

[0046] The temperatures of the twin-screw extruder from the feed inlet to the die are as follows: Zone 1 190℃, Zone 2 190℃, Zone 3 200℃, Zone 4 200℃, Zone 5 210℃, Zone 6 210℃, Zone 7 210℃, Zone 8 210℃, and Zone 9 210℃. The side feed inlet is located in Zone 8, and the screw speed is 400 r / min. Comparative Example 3:

[0047] 79.4 parts of polypropylene YPJ1215C, 15 parts of inorganic filler talc, 5 parts of POE (ethylene-octene copolymer 8842), 0.1 parts of phosphite antioxidant, 0.2 parts of hindered phenolic antioxidant, and 0.3 parts of processing aid calcium stearate were mixed evenly and then fed into a twin-screw extruder through the main feed port. The polypropylene composite material was obtained by extrusion, stranding, and granulation.

[0048] The temperatures of the twin-screw extruder from the feed inlet to the die are as follows: Zone 1 190℃, Zone 2 190℃, Zone 3 200℃, Zone 4 200℃, Zone 5 210℃, Zone 6 210℃, Zone 7 210℃, Zone 8 210℃, and Zone 9 210℃. The side feed inlet is located in Zone 8, and the screw speed is 400 r / min.

[0049] Gloss Test: The surface gloss of the polypropylene composite materials of Examples 1-5 and Comparative Examples 1-3 was tested according to ASTM D523 standard. A 100*100*4 square plate was used as the sample, and the optical fiber incident angle was 60°. Tests were conducted on both smooth and textured surfaces. The results are as follows:

[0050]

[0051] Compared to Comparative Examples 1-3, Example 1 incorporated both ultra-high molecular weight polyethylene (UHMWPE) and alkyl carboxylate nucleating agents, while Comparative Examples 1, 2, and 3 did not include UHMWPE, alkyl carboxylate nucleating agents, or either. Therefore, the polypropylene composite material prepared in Example 1 exhibited significantly better gloss than those in Comparative Examples 1-3. This indicates that UHMWPE and alkyl carboxylate nucleating agents have a synergistic effect in reducing the gloss of the polypropylene composite material.

[0052] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A low-gloss polypropylene composite material, characterized in that, It is prepared from the following components in parts by weight: 53.4-89.3 parts polypropylene, 5-30 parts inorganic filler, 2-10 parts POE, 3-5 parts ultra-high molecular weight polyethylene, 0.2-0.6 parts nucleating agent, 0.2-0.4 parts antioxidant, and 0.3-0.6 parts processing aid.

2. The low-gloss polypropylene composite material according to claim 1, characterized in that, The polypropylene mentioned is copolymer polypropylene.

3. The low-gloss polypropylene composite material according to claim 1, characterized in that, The inorganic filler is any one of talc, calcium carbonate, barium sulfate, wollastonite, and whiskers.

4. The low-gloss polypropylene composite material according to claim 1, characterized in that, The POE is an ethylene-octene copolymer or an ethylene-butene copolymer.

5. The low-gloss polypropylene composite material according to claim 1, characterized in that, The ultra-high molecular weight polyethylene is unbranched linear polyethylene with a molecular weight of 1.5 million or more.

6. The low-gloss polypropylene composite material according to claim 1, characterized in that, The nucleating agent is an alkyl carboxylate nucleating agent.

7. The low-gloss polypropylene composite material according to claim 1, characterized in that, The antioxidant is one or a combination of two of the following: phosphite antioxidants or hindered phenolic antioxidants.

8. The low-gloss polypropylene composite material according to claim 1, characterized in that, The processing aid is calcium stearate or zinc stearate.

9. A method for preparing a low-gloss polypropylene composite material as described in any one of claims 1-8, characterized in that, Includes the following steps: After mixing 53.4-89.3 parts of polypropylene, 5-30 parts of inorganic filler, 2-10 parts of POE, 3-5 parts of high-molecular-weight polyethylene, 0.2-0.6 parts of nucleating agent, 0.2-0.4 parts of antioxidant, and 0.3-0.6 parts of processing aid evenly, the mixture is fed into a twin-screw extruder through the main feed port. The polypropylene composite material is obtained through extrusion, stranding, and granulation.

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