Scratch-resistant polypropylene material for automotive trim and preparation method of scratch-resistant polypropylene material

Abstract

The invention relates to the field of polypropylene materials, in particular to a scratch-resistant polypropylene material for automotive trim and a preparation method of the scratch-resistant polypropylene material. The polypropylene material comprises the following components in parts by mass: 76-82 parts of polypropylene resin; 16 parts to 23 parts of inorganic filler; 0.2 part to 0.6 part of an antioxidant; 0.2 part to 0.4 part of a dispersing agent; and 1-3 parts of a modified scratch-resistant agent, wherein the modified scratch-resistant agent comprises fatty acid amide taking plant fiber as a carrier. By using the fatty acid amide modified scratch-resistant agent taking the plant fiber as the carrier and through the synergistic effect of fatty acid amide and plant fiber, the polypropylene material has excellent and lasting scratch resistance, and is beneficial to keeping the attractiveness of automotive upholstery.

Description

Technical Field

[0001] The present application relates to the field of polypropylene materials, and in particular to a scratch-resistant polypropylene material for automobile interior decoration and a preparation method thereof. Background Art

[0002] Polypropylene (PP) boasts abundant resources and low cost. Compared to other general-purpose plastics, it boasts excellent mechanical properties, low density, superior rigidity, high strength, and excellent electrical insulation. It is widely used in the automotive sector, becoming the largest and fastest-growing automotive plastic. In recent years, the rapid development of the automotive industry has placed increasingly stringent requirements on interior materials. During manufacturing, vehicle assembly, transportation, storage, and subsequent use by consumers, polypropylene interior components such as dashboards, door panels, and pillar trims are susceptible to scratches from sharp objects, such as hard objects or fingers. The uneven light scattering from scratched surfaces causes visible damage, affecting the appearance and limiting the widespread use of polypropylene in interior components.

[0003] Currently, the scratch resistance of polypropylene materials is often improved by adding scratch resistant agents (such as silicones and fatty acid amides). Among them, silicone scratch resistant agents refer to long-chain molecules with an inorganic silicon-oxygen structure with polysiloxane chains as the main body. They have low surface tension and can form an aggregate phase on the surface of the material after blending with polypropylene to reduce the friction coefficient of the material surface. However, polysiloxane has a high molecular weight and is difficult to migrate to the surface of the workpiece. Therefore, the added dosage is often relatively high. Due to its high molecular weight, the processing performance of the material will also deteriorate after the silicone scratch resistant agent is added to the system. There are disadvantages such as large addition amount, high cost, and significant reduction in material processing performance.

[0004] Fatty acid amide scratch resistant agents are small molecule additives with an amide group and a long carbon chain at the chain end. The polar amide group has poor compatibility with polypropylene, while the non-polar carbon chain has good compatibility with polypropylene. This makes it easy for it to migrate to the surface area during the preparation of polypropylene. The amide group forms a thin lubricating layer on the surface of polypropylene, reducing the surface friction coefficient of the material and improving the scratch resistance of polypropylene. Therefore, compared with silicone scratch resistant agents, the addition amount of amide scratch resistant agents is low, which reduces production costs. However, this small molecule additive may precipitate under the action of light and heat, reducing the scratch resistance of the polypropylene material. It can also cause the surface to become sticky and produce volatile organic compounds, affecting the performance of the product. How to improve the excellent scratch resistance of polypropylene materials while maintaining the durability of scratch resistance has become a research hotspot in polypropylene modification in recent years. Summary of the Invention

[0005] In order to solve the problem of poor durability of scratch resistance of polypropylene materials for automobile interiors, the present application provides a scratch-resistant polypropylene material for automobile interiors and a preparation method thereof. The polypropylene material uses fatty acid amide with plant fiber as a carrier as a scratch-resistant agent, and has both excellent and long-lasting scratch resistance.

[0006] A first aspect of the present application provides a scratch-resistant polypropylene material for automotive interiors, the polypropylene material comprising the following components, calculated in parts by mass: 76-82 parts of polypropylene resin; 16-23 parts of inorganic filler; 0.2-0.6 parts of antioxidant; 0.2-0.4 parts of dispersant; and 1-3 parts of a modified scratch-resistant agent; wherein the modified scratch-resistant agent comprises fatty acid amide with plant fiber as a carrier, and the preparation method of the modified scratch-resistant agent comprises at least the following steps: (1) Preparing ammonia-adsorbing plant fibers: placing plant fibers in a first reaction vessel, introducing ammonia, and placing the fibers at 20° C. to 25° C. and 0.2 MPa to 0.5 MPa for 3 to 7 hours to obtain ammonia-adsorbing plant fibers, wherein the plant fibers include one or more of kapok fibers, bamboo fibers, coconut shell fibers, jute fibers, flax fibers, palm fibers, straw fibers, and reed fibers; (2) In situ synthesis of fatty acid amide with plant fiber as carrier: Add fatty acid and catalyst into a second reaction vessel, raise the temperature to 100°C-120°C, then add the plant fiber adsorbing ammonia described in step (1), stir and react at 0.3MPa-0.5MPa and 170°C-180°C for 4 hours-8 hours to obtain fatty acid amide with plant fiber as carrier, wherein the fatty acid includes an unsaturated hydrocarbon chain, and the number of carbon atoms in the unsaturated hydrocarbon chain is 18-22.

[0007] In this application, "fatty acid" refers to an organic compound composed of a long-chain hydrocarbon group and a carboxylic acid group, and its general formula is: R-COOH, wherein R is a saturated or unsaturated hydrocarbon chain.

[0008] Plant fiber is a fibrous material with a network-like pore structure that is widely found in nature. Compared to synthetic fibers, plant fiber offers advantages such as low density, high stiffness, high specific strength, green biodegradability, and low cost. These plant fibers possess excellent porosity, with a large number of evenly distributed pores primarily composed of micropores (pore diameter less than 2 nm) and mesopores (pore diameter 2-50 nm), which matches the kinetic diameter of ammonia. Utilizing physical adsorption forces based on molecular size effects, the pores of the plant fibers can adsorb ammonia molecules. This improves the ammonia adsorption rate of the plant fibers at temperatures between 20°C and 25°C, 0.2 MPa and 0.5 MPa, and under a slightly positive pressure. Furthermore, by adding ammonia-adsorbing plant fibers to a molten fatty acid, fatty acid amides are generated in situ using the plant fibers as carriers. This preparation method not only helps inhibit the escape of ammonia from the plant pores and improve the fatty acid amide loading rate in the resulting modified scratch-resistant agent, but also enhances the binding effect of the plant fibers on the fatty acid amide molecules.

[0009] The use of inorganic fillers in polypropylene is beneficial to improving the rigidity, heat resistance and dimensional stability of polypropylene. However, since inorganic fillers are usually white, scratches are prone to whitening, resulting in a decrease in the scratch resistance of the material. The applicant has found through research that the use of fatty acid amide with plant fiber as a carrier as a scratch resistance agent is conducive to achieving excellent and long-lasting scratch resistance. This may be due to the presence of amide groups in fatty acid amide and polar groups such as hydroxyl and carboxyl groups in plant fibers, which makes the polarity difference between the modified scratch resistance agent and the non-polar polypropylene matrix. During the preparation process of the polypropylene material, the modified scratch resistance agent tends to migrate to the non-polar polypropylene matrix. When the fatty acid amide is moved to the surface area of ​​PP, the carbon chains of the fatty acid amide are arranged in a direction in the surface area of ​​PP, so that the stress of the contact surface of the PP material is transformed from PP-PP to plant fiber-fatty acid amide-PP, forming a lubricating layer of low shear strength interface, which is beneficial to the improvement of lubrication performance and reduction of friction coefficient in the surface area, and improves the scratch resistance of the PP material; and the fatty acid amide is loaded on the plant fiber, and the long carbon chain of the fatty acid amide has a certain steric hindrance, which can prevent the plant fiber from agglomerating into clusters to form stress concentration points, thereby achieving uniform dispersion of the plant fiber in the polypropylene matrix in the surface area, reducing the stress concentration caused by it and producing The possibility of defects is reduced, and toughness and rigidity support are provided. The yield strength of the surface area of ​​the polypropylene material is improved, which is beneficial to reducing the depth of scratches when scratched; further, the carbon chain loaded by the plant fiber is similar to the main chain structure of the polypropylene, which is beneficial to improving the interface compatibility between the plant fiber and the polypropylene matrix, thereby strengthening the interface bonding strength between the plant fiber and the polypropylene matrix, further improving the toughness of the surface area of ​​the material, realizing effective conduction of stress at the interface, dispersing local stress, avoiding stress concentration that damages the polypropylene matrix, and thus facilitating further improvement of scratch resistance; the carbon chain improves the compatibility between the modified scratch resistance agent and the polypropylene matrix At the same time, the selection of unsaturated chains can appropriately reduce the degree of interaction between the modified scratch-resistant agent and the polypropylene chain segment, which is beneficial to the migration of the modified scratch-resistant agent to the surface area of ​​the polypropylene material. The number of carbon atoms in the unsaturated hydrocarbon chain is 18-22, which makes the modified scratch-resistant agent further have excellent thermal stability and migration rate; and in the preparation process of the above-mentioned modified scratch-resistant agent, the carboxyl group of the fatty acid has a probability of reacting with the hydroxyl group of the plant fiber under high temperature environment to form an ester group, thereby further weakening the strong polarity of the plant fiber, further improving the interface strength, and further improving the scratch resistance. At the same time, it is also beneficial to reduce the water absorption of the plant fiber due to the hydroxyl group.

[0010] When ammonia is adsorbed on the plant fiber, fatty acid amide is generated in situ. The plant fiber has a strong binding effect on the fatty acid amide molecules, which can effectively reduce the probability of the polypropylene material precipitating onto the surface of the polypropylene material after use at high temperature and light, thereby avoiding the decline in scratch resistance and the occurrence of stickiness and odor, so that the polypropylene material prepared in the present application exhibits excellent and long-lasting scratch resistance; further, in the subsequent use process, when the amide molecules in the surface area of ​​the polypropylene material are lost due to friction or cleaning, the unlost fatty acid amide in the plant fiber can still synergize with the plant fiber to form a self-repairing long-lasting scratch-resistant layer, thereby maintaining the excellent scratch resistance of the polypropylene material.

[0011] In summary, the polypropylene material prepared in the present application has excellent and long-lasting scratch resistance by adding aliphatic amide with plant fiber as a carrier as a scratch-resistant agent.

[0012] In any embodiment, in step (1), the plant fiber is pre-treated, and the pre-treatment is to immerse the plant fiber in ethanol to clean and remove impurities, then wash it with deionized water and place it at a temperature of 80°C to 120°C to dry for 3 hours to 5 hours.

[0013] Through research, the applicant further discovered that using plant fibers that have been pre-treated only by washing with ethanol and water as a carrier of fatty acid amide is beneficial to further improve the scratch resistance. This may be because the above-mentioned pre-treatment has not undergone alkali treatment or other treatments, which can retain the lignin in the plant fibers. Lignin has a rigid aromatic ring structure, which can inhibit the diffusion and stacking of polypropylene molecular chains to the surface of the crystal nucleus, alleviate the crystallization process of polypropylene, and thus facilitate the migration of the modified scratch-resistant agent to the surface area of ​​​​polypropylene. It is also beneficial to improve the toughness of the surface area of ​​​​polypropylene and appropriately reduce the hardness of the surface area, so that the polypropylene material is easier to disperse local stress through force conduction between plant fiber-fatty acid amide-polypropylene molecular chains when scratched, avoiding the stress concentration in local areas during scratching, resulting in increased material damage, thereby further improving the scratch resistance of the material; and lignin can absorb ultraviolet rays, improve the UV resistance of polypropylene materials, and reduce the oxidation and degradation rate of the surface of polypropylene materials during use, which is beneficial to maintaining scratch resistance.

[0014] In any embodiment, the plant fiber includes one or more of kapok fiber, bamboo fiber, and jute fiber.

[0015] Through research, the applicant further discovered that the above-mentioned plant fibers as carriers of fatty acid amides are more conducive to further improving the scratch resistance of polypropylene materials. This may be because the above-mentioned plant fibers have excellent porosity or an appropriate lignin content, which is conducive to increasing the loading rate of fatty acid amide in the modified scratch-resistant agent, improving the interfacial bonding strength between the plant fibers and the polypropylene matrix, or facilitating the migration of the modified scratch-resistant agent to the surface and making the surface area of ​​the polypropylene material have appropriate hardness and toughness, thereby facilitating further improvement of the scratch resistance of the material.

[0016] In any embodiment, the plant fiber includes kapok fiber and bamboo fiber, and the mass ratio of the kapok fiber to the bamboo fiber is 1:1.

[0017] Compounding the above-mentioned plant fibers as a carrier of fatty acid amide is more conducive to further improving the scratch resistance of polypropylene materials.

[0018] In any embodiment, the number of carbon atoms in the unsaturated hydrocarbon chain is 20-22.

[0019] The number of carbon atoms in the hydrocarbon chain of the fatty acid within the above range is more conducive to the modified scratch-resistant agent migrating to the surface area of ​​the polypropylene material to exert a scratch-resistant effect, which is conducive to further improving the scratch resistance of the polypropylene material.

[0020] In any embodiment, the polypropylene resin includes a first polypropylene resin and a second polypropylene resin, and the first polypropylene resin and the second polypropylene resin are one or more of homopolymer polypropylene, random copolymer polypropylene or block copolymer polypropylene; wherein the melt index of the first polypropylene resin at 230°C and 2.16kg is 50-100g / 10min, and the melt index of the second polypropylene resin at 230°C and 2.16kg is 0.5-35g / 10min.

[0021] The addition of plant fibers and inorganic fillers reduces the fluidity of the polypropylene melt, while the modified anti-scratch agent is more likely to migrate to the surface area of ​​the polypropylene material under high fluidity to exert its scratch resistance. Furthermore, polypropylene for injection molding of interior parts requires good melt fluidity. The embodiments of this application, through the compounding of low melt index and high melt index polypropylene resins, are beneficial for improving the fluidity of the polypropylene material prepared in the embodiments of this application, achieving an increase in the migration rate of the modified anti-scratch agent and thin-wall injection molding, and also facilitating the balance of rigidity and toughness and impact resistance of the polypropylene material, thereby taking into account the requirements of scratch resistance, mechanical properties, and processing performance.

[0022] In any embodiment, in the polypropylene resin, the mass ratio of the first polypropylene resin to the second polypropylene resin is 3:7-7:3.

[0023] The mass ratio of the first polypropylene resin to the second polypropylene resin has excellent flow properties within the above range, which is further conducive to the migration of the modified scratch-resistant agent to the surface area of ​​the polypropylene material to exert its effect and achieve a balance between the rigidity and toughness of the material, while meeting the requirements of scratch resistance, mechanical properties and processing performance.

[0024] In any embodiment, the inorganic filler includes one or more of talc and wollastonite.

[0025] The addition of these inorganic fillers improves polypropylene's rigidity, heat resistance, and dimensional stability. Compared to spherical calcium carbonate inorganic fillers, talc and wollastonite typically have a flake structure, which interacts more strongly with the polypropylene matrix, enhancing the strength and toughness of the polypropylene material and further improving its scratch resistance. Furthermore, talc is relatively low-cost, making it more suitable for industrial production.

[0026] In any embodiment, the catalyst includes one or more of tetraisopropyl titanate, tetra-n-butyl titanate, and tetra-n-propyl zirconate.

[0027] In any embodiment, the antioxidant includes a hindered phenol primary antioxidant 1010 and a phosphite secondary antioxidant 168, and the mass ratio of the antioxidant 1010 to the antioxidant 168 is 1:2.

[0028] The combined use of antioxidants 1010 and 168 is beneficial to improving the thermal stability and antioxidant properties of polypropylene materials, and is beneficial to further maintaining the scratch resistance of polypropylene materials.

[0029] In any embodiment, the dispersant comprises ethylene bisstearamide.

[0030] The molecular structure of ethylene bisstearamide contains both polar groups and non-polar groups. The polar bisamide group in the middle of the structure can form a certain intermolecular force with the inorganic filler, which is conducive to the dispersion of the inorganic filler. The non-polar long-chain alkyl groups at both ends have good compatibility with polypropylene, which can reduce the interface between the matrix resin and the filler, thereby achieving the purpose of toughening the surface and further improving the scratch resistance of the material.

[0031] The present application also provides a method for preparing a scratch-resistant polypropylene material for automobile interior decoration, which is characterized by at least comprising the following steps: Polypropylene resin, inorganic filler, antioxidant and dispersant are mixed according to the mass ratio and added to the main feeding port of the twin-screw extruder, and the modified scratch-resistant agent is added to the side feeding port of the twin-screw extruder. The temperature of each zone of the twin-screw extruder is 180°C-220°C. After extrusion and drying, the scratch-resistant polypropylene material for automotive interior is obtained.

[0032] Adding the modified scratch-resistant agent through the side feed port and controlling the temperature of each zone of the extruder to 180°C-220°C is beneficial for the migration of the modified scratch-resistant agent to the surface area of ​​the polypropylene material, and is also beneficial for reducing the fiber damage caused by strong shearing of plant fibers and the degradation caused by processing temperature, thereby helping the modified scratch-resistant agent to exert excellent scratch resistance and further improve the scratch resistance of polypropylene.

[0033] In summary, this application has the following beneficial effects: (1) Under the temperature of 20℃-25℃, 0.2MPa-0.5MPa and slightly positive pressure environment, the pores of plant fibers can use the physical adsorption force based on the molecular size effect to adsorb ammonia molecules. Plant fibers that adsorb ammonia are added to the molten state of fatty acids to generate fatty acid amides in situ with plant fibers as carriers. The obtained modified scratch-resistant agent has a high fatty acid amide loading rate and binding ability to fatty acid amides. When applied to polypropylene materials, the modified scratch-resistant agent is distributed in the surface area of ​​the polypropylene material. The directional arrangement of the carbon chains of the fatty acid amide causes the stress of the contact surface of the polypropylene material to change from polypropylene-polypropylene to plant fiber-fatty acid amide-polypropylene, forming a lubricating layer of low shear strength interface, thereby improving the scratch resistance of the polypropylene material. And the long carbon chain of fatty acid amide has certain steric hindrance, can prevent plant fiber from agglomerating into clusters to form stress concentration points, realize the uniform dispersion of plant fiber in the surface area polypropylene matrix, the yield strength of polypropylene material surface area is improved, is conducive to reducing the depth of scratches during scratching; Carbon chain is further conducive to improving the interfacial compatibility between plant fiber and polypropylene matrix, thereby strengthening the interfacial bonding strength of plant fiber and polypropylene matrix, realizes the effective conduction of stress at the interface, is conducive to the further improvement of scratch resistance. Utilize the strong binding effect of plant fiber on fatty acid amide molecules in modified scratch-resistant agent, can effectively reduce the use of polypropylene material under high temperature, illumination environment, the probability of fatty acid amide molecules being precipitated to the surface of polypropylene material, makes the polypropylene material prepared by the present application show excellent and lasting scratch resistance.

[0034] (2) The selection of plant fiber pretreatment and the type of plant fiber are conducive to further improving the scratch resistance of polypropylene materials.

[0035] (3) The compounding of low melt index polypropylene resin and high melt index polypropylene resin and controlling the ratio within an appropriate range are beneficial to improving the flow properties of the polypropylene material prepared in the embodiment of the present application, achieving the improvement of the migration rate of the modified scratch resistant agent and thin-wall injection molding, and also beneficial to achieving the rigidity and toughness balance and impact resistance of the polypropylene material, thereby taking into account the requirements of scratch resistance, mechanical properties and processing performance. DETAILED DESCRIPTION

[0036] The present application is further described in detail below with reference to the following examples and comparative examples.

[0037] In the following preparation examples and embodiments, if no specific conditions are specified, the preparations were carried out according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from common commercial sources.

[0038] Preparation Example 1 (1) Kapok fibers (purchased from Shanghai Panda Textile Co., Ltd.) were pretreated as follows: the fibers were immersed in anhydrous ethanol to clean and remove impurities, then rinsed with deionized water until neutral, and then dried in an oven at 100°C for 4 hours. 5 g of dried kapok fibers were weighed and placed in the first reactor. Ammonia gas was introduced and the pressure in the reactor was controlled at 0.4 MPa. The reactor was left at 25°C for 5 hours until the kapok fibers were saturated with ammonia.

[0039] (2) 10 g of erucic acid and 0.05 g of tetraisopropyl titanate were added to a second reaction kettle and heated to 120°C to melt the erucic acid. 5 g of the ammonia-adsorbed kapok fiber was added, and the temperature was raised to 180°C. The mixture was stirred at 0.4 MPa and 100 rpm for 6 hours. After the reaction, the liquid component of the product was filtered to obtain a modified scratch-resistant agent.

[0040] Preparation Example 2 The preparation method of Preparation Example 2 is basically the same as that of Preparation Example 1, except that the pretreatment of the kapok fiber in step (1) of Preparation Example 2 is as follows: the kapok fiber is immersed in ethanol to clean and remove impurities, and then immersed in a sodium hydroxide aqueous solution (the concentration of sodium hydroxide is 5wt%) at 25°C for 1 hour to remove lignin and other components, and then rinsed with deionized water until neutral and placed in a 100°C oven to dry for 4 hours.

[0041] Preparation Example 3-5 The preparation methods of Preparation Examples 3-5 are basically the same as those of Preparation Example 1, except that the types of fibers are different, and the rest remain the same as Preparation Example 1.

[0042] Preparation Example 3: Bamboo fiber of equal mass (purchased from Sichuan Yikeji Bamboo Fiber Co., Ltd.) was used to replace kapok fiber.

[0043] Preparation Example 4: Jute fiber (purchased from Nanjing Xinhe Textile Co., Ltd.) of equal mass was used to replace kapok fiber.

[0044] Preparation Example 5: A mixture of kapok fiber and bamboo fiber in a mass ratio of 1:1 is used to replace the kapok fiber, and the sum of the masses of the kapok fiber and bamboo fiber in Preparation Example 5 is the same as the mass amount of the kapok fiber in Preparation Example 1, wherein the bamboo fiber is purchased from Sichuan Yikeji Bamboo Fiber Co., Ltd.

[0045] Preparation Example 6 The preparation method of Preparation Example 6 is basically the same as that of Preparation Example 1, except that oleic acid of equal mass is used instead of erucic acid, and the rest remains the same as Preparation Example 1.

[0046] Preparation Example 7 (1) Kapok fibers (purchased from Shanghai Panda Textile Co., Ltd.) were pretreated as follows: the kapok fibers were immersed in anhydrous ethanol to clean and remove impurities, then rinsed with deionized water until neutral, and then dried in an oven at 100°C for 4 hours.

[0047] (2) 10 g of erucic acid, 0.05 g of tetraisopropyl titanate, and 5 g of the plant fiber dried in step (1) were added to a reactor and heated to 120°C to melt the erucic acid. Ammonia gas was introduced while controlling the pressure in the reactor to 0.4 MPa. The temperature was raised to 180°C and the reaction was stirred at 0.4 MPa and 100 rpm for 6 hours. After the reaction was completed, the liquid component in the product was filtered to obtain a modified scratch-resistant agent. Example 1

[0048] Weigh 40.75 parts of a first polypropylene resin (copolymer polypropylene resin BX3900, purchased from SK Company of South Korea, with a melt index of 55.8 g / 10 min at 230°C and 2.16 kg), 40.75 parts of a second polypropylene resin (copolymer polypropylene resin EP300M, purchased from Sinopec, with a melt index of 10 g / 10 min at 230°C and 2.16 kg), 16 parts of talc, 0.1 parts of antioxidant 1010, 0.2 parts of antioxidant 168, 0.2 parts of dispersant ethylene diacrylate copolymer, and 0.5 parts of ethylene diacrylate copolymer. Fatty amide is mixed evenly in a high-speed mixer, and the mixture is added to a twin-screw extruder through the main feed port. 2 parts by mass of the modified scratch-resistant agent prepared in Preparation Example 1 is added to the twin-screw extruder through the side feed port located in zone 6. The temperature of each section of the barrel from the feed port to the die is controlled to be 180°C, 210°C, 210°C, 220°C, 220°C, 210°C, 210°C, 210°C, 205°C, and 205°C, respectively. At a twin-screw speed of 500rpm, melt extrusion and granulation are performed to obtain a scratch-resistant polypropylene material for automotive interiors. The prepared polypropylene material is added with black polypropylene masterbatch according to Volkswagen's PV 3952-2019-03 standard, and an injection molding machine is used to inject a K9A polypropylene textured sample at 210-220°C for scratch resistance testing.

[0049] Example 2-3 The preparation method of Example 2-3 is basically similar to that of Example 1, except that the mass amount of the modified scratch-resistant agent is different, the total mass fraction of the raw materials is changed accordingly, and the rest remains the same as Example 1.

[0050] Example 2: The mass fraction of the modified scratch-resistant agent is 1 part.

[0051] Example 3: The mass fraction of the modified scratch-resistant agent is 3 parts.

[0052] Examples 4-5 The preparation method of Example 4-5 is basically similar to that of Example 1, except that the sum of the mass fractions of the first polypropylene resin and the second polypropylene resin in Example 4-5 remains the same as the sum of the mass fractions of the first polypropylene resin and the second polypropylene resin in Example 1, but the mass ratio of the first polypropylene resin to the second polypropylene resin in Example 4-5 is changed, and the rest remains the same as Example 1.

[0053] Example 4: The mass ratio of the first polypropylene resin to the second polypropylene resin is 3:7.

[0054] Example 5: The mass ratio of the first polypropylene resin to the second polypropylene resin is 7:3.

[0055] Examples 6-7 The preparation methods of Examples 6-7 are basically similar to those of Example 1, except that in Example 6, the first polypropylene resin is used in place of the second polypropylene resin in equal parts by mass, and in Example 7, the second polypropylene resin is used in place of the first polypropylene resin in equal parts by mass. Example 8

[0056] The preparation method of Example 8 is basically similar to that of Example 1, except that the modified scratch-resistant agent prepared in Preparation Example 2 is used in equal parts by mass to replace the modified scratch-resistant agent prepared in Preparation Example 1, and the rest remains the same as in Example 1. Example 9

[0057] The preparation method of Example 9 is basically similar to that of Example 1, except that the modified scratch-resistant agent prepared in Preparation Example 3 is used in equal parts by mass to replace the modified scratch-resistant agent prepared in Preparation Example 1, and the rest remains the same as in Example 1. Example 10

[0058] The preparation method of Example 10 is basically similar to that of Example 1, except that the modified scratch-resistant agent prepared in Preparation Example 4 is used in equal parts by mass to replace the modified scratch-resistant agent prepared in Preparation Example 1, and the rest remains the same as in Example 1. Example 11

[0059] The preparation method of Example 11 is basically similar to that of Example 1, except that the modified scratch-resistant agent prepared in Preparation Example 5 is used in equal parts by mass to replace the modified scratch-resistant agent prepared in Preparation Example 1, and the rest remains the same as in Example 1. Example 12

[0060] The preparation method of Example 12 is basically similar to that of Example 1, except that the modified scratch-resistant agent prepared in Preparation Example 6 is used in equal parts by mass to replace the modified scratch-resistant agent prepared in Preparation Example 1, and the rest remains the same as Example 1. Example 13

[0061] The preparation method of Example 13 is basically similar to that of Example 1, except that the modified anti-scratch agent is added to the twin-screw extruder through the main feed port.

[0062] Comparative Example 1 The preparation method of Comparative Example 1 is basically similar to that of Example 1, except that the modified anti-scratch agent is not added.

[0063] Comparative Example 2 The preparation method of Comparative Example 2 is basically similar to that of Example 1, except that an equal amount of erucamide is used to replace the modified scratch-resistant agent prepared in Preparation Example 1, and the rest remains the same as Example 1.

[0064] Comparative Example 3 The preparation method of Comparative Example 3 is basically similar to that of Example 1, except that an equal amount of kapok fiber is used to replace the modified scratch-resistant agent prepared in Preparation Example 1, and the rest remains the same as Example 1.

[0065] Comparative Example 4 The preparation method of Comparative Example 4 is basically similar to that of Example 1, except that 0.6 parts by mass of kapok fiber and 1.4 parts by mass of erucamide are used to replace the modified scratch-resistant agent prepared in Preparation Example 1, and the rest remains the same as Example 1.

[0066] Comparative Example 5 The preparation method of Comparative Example 5 is basically similar to that of Example 1, except that the modified scratch-resistant agent prepared in Preparation Example 7 is used in equal parts by mass to replace the modified scratch-resistant agent prepared in Preparation Example 1, and the rest remains the same as Example 1. Performance testing

[0067] 1. Scratch resistance The scratch resistance test was conducted using Volkswagen's PV 3952-2019-03 standard. The specific method was to use an ERICHSEN cross-scratch tester, model 430P-I. A spherical indenter with a diameter of 1 mm was used to cross-scratch the test sample with a force of 10 N. The cross-scratch speed was 1000 mm / min, the cross-scratch area size was 40×40 mm, and the cross-scratch distance was 2 mm. According to standard GB / T 8416, the sample's lightness value (L1) before scratching was measured, followed by the sample's lightness value (L2) after the scratch test. The test equipment was a Hunterlab UltraScan VIS colorimeter. The two values ​​were subtracted (L1 - L2), and the absolute value was taken to determine the change in lightness value (ΔL) before and after scratching. This change in lightness value (ΔL) was used to assess the material's scratch resistance. A smaller ΔL indicates better scratch resistance; a larger ΔL indicates more pronounced whitening after scratching, meaning more visible scratches indicate poorer scratch resistance. Five samples were tested for each sample, and the average value was calculated.

[0068] 2. Durability of scratch resistance The sample was placed in a high-temperature constant temperature test chamber at 120°C for 168 hours, and then a scratch test was performed using the above-mentioned scratch resistance test method. The lightness value L2' of the sample after the test was completed was measured, and the absolute value △L' of (L1-L2') was used to predict the durability of the scratch resistance of the polypropylene material.

[0069] The polypropylene samples prepared in Examples 1-13 and Comparative Examples 1-5 were tested, and the test results are shown in Tables 1 and 2, respectively.

[0070] Table 1 Scratch resistance of polypropylene in Example 1 and Comparative Examples 1-5 Experimental group △L △L’ Example 1 0.57 0.74 Comparative Example 1 1.83 3.24 Comparative Example 2 0.85 1.96 Comparative Example 3 1.94 3.33 Comparative Example 4 1.27 2.48 Comparative Example 5 1.71 2.55 Referring to Table 1, it can be seen from the comparison between Example 1 and Comparative Example 1 that the addition of the modified anti-scratch agent prepared in the present application greatly improves the excellent scratch resistance and durability of the polypropylene material. As can be seen from the comparison between Example 1 and Comparative Example 2, compared with the direct addition of erucamide, the addition of erucamide with plant fiber as a carrier has a synergistic effect that is conducive to further improving the scratch resistance of the polypropylene material, and by binding the erucamide molecules to migrate to the surface of the material, it has a greater benefit in improving the durability of the scratch resistance. As can be seen from the comparison between Example 1 and Comparative Example 3, when plant fiber is directly added, its dispersibility in the polypropylene resin is poor, and it is easy to agglomerate to form stress concentration points, which in turn worsens the scratch resistance of the polypropylene material. As can be seen from the comparison between Example 1 and Comparative Example 4, when a physical mixture of erucamide and plant fiber is added, erucamide can improve the scratch resistance of the polypropylene material, but only through physical mixing, the binding effect of plant fiber on erucamide is small, and the durability of the polypropylene scratch resistance is poor. A comparison between Example 1 and Comparative Example 5 shows that the preparation method of first preparing ammonia-adsorbing plant fibers and then in-situ generating fatty acid amides improves the plant fiber's loading rate and binding capacity for erucamide, thereby further enhancing the scratch resistance of the polypropylene material. In contrast, Comparative Example 5, in which the plant fibers, erucic acid, and ammonia react in a single step, results in less ammonia adsorption by the plant fibers. The resulting modified scratch-resistant agent has a low loading rate of erucamide on the plant fibers, resulting in a weaker improvement in the scratch resistance of the polypropylene material.

[0071] Table 2 Scratch resistance of polypropylene of Examples 1-13 Experimental group △L △L’ Example 1 0.57 0.74 Example 2 0.68 0.87 Example 3 0.54 0.68 Example 4 0.64 0.84 Example 5 0.69 0.88 Example 6 0.89 1.06 Example 7 0.82 1.03 Example 8 0.76 1.01 Example 9 0.62 0.83 Example 10 0.75 0.98 Example 11 0.50 0.66 Example 12 0.65 0.84 Example 13 0.92 1.18 As shown in Table 2, Examples 1-3 show that when the modified anti-scratch agent is added in amounts of 1 to 3 parts, the polypropylene material exhibits excellent and long-lasting scratch resistance. When the modified anti-scratch agent is increased from 2 to 3 parts, the surface lubricating layer becomes saturated, and the improvement in initial scratch resistance levels off, but this further improves the durability of the scratch resistance.

[0072] It can be seen from Examples 1, 4, and 5 that when the mass ratio of the first polypropylene resin to the second polypropylene resin in the polypropylene resin is 3:7-7:3, the polypropylene material has excellent fluidity, toughness, and rigidity, resulting in excellent and long-lasting scratch resistance.

[0073] From the comparison between Example 1 and Examples 6 and 7, it can be seen that when the polypropylene resin contains only the first polypropylene resin, the hardness of the polypropylene material is too low, which deteriorates the scratch resistance of the polypropylene material; when the polypropylene resin contains only the second polypropylene resin, the hardness of the polypropylene material is too high and the fluidity is poor, which is not conducive to the scratch resistance of the polypropylene material; the compounding of the first polypropylene resin and the second polypropylene resin in the polypropylene resin is conducive to comprehensively improving the scratch resistance of the polypropylene material.

[0074] From the comparison between Example 1 and Example 8, it can be seen that when pre-treating the plant fiber, not performing alkali treatment is beneficial to further improving the scratch resistance of polypropylene.

[0075] From the comparison of Examples 1, 9, and 10, it can be seen that the use of kapok fiber or bamboo fiber as plant fiber is beneficial to increasing the loading rate and binding capacity of fatty acid amide and improving the scratch resistance of polypropylene.

[0076] From the comparison between Examples 1 and 11, it can be seen that the compounding of kapok fiber and bamboo fiber as plant fibers is beneficial to further improve the scratch resistance of the polypropylene material.

[0077] From the comparison of Examples 1 and 12, it can be seen that the number of carbon atoms in the unsaturated hydrocarbon chain in the fatty acid amide is 20-22, which is conducive to the migration of the modified scratch-resistant agent to the surface area of ​​the polypropylene material to exert a scratch-resistant effect, while taking into account the excellent molecular stability, which is conducive to further improving the scratch resistance of polypropylene.

[0078] From the comparison between Example 1 and Example 13, it can be seen that adding the modified scratch-resistant agent through the side feeding port is beneficial to the migration of the modified scratch-resistant agent to the surface area of ​​the polypropylene material, and is also beneficial to reducing the decomposition and damage of the plant fiber, thereby helping the modified scratch-resistant agent to exert better scratch resistance.

[0079] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A scratch-resistant polypropylene material for automobile interior, characterized in that: The polypropylene material includes the following components calculated in parts by mass: Polypropylene resin 76-82 parts; 16-23 parts of inorganic filler; 0.2-0.6 parts of antioxidant; Dispersant 0.2-0.4 parts; 1-3 parts of modified scratch-resistant agent; The modified scratch-resistant agent comprises fatty acid amide with plant fiber as a carrier, and the preparation method of the modified scratch-resistant agent comprises at least the following steps: (1) Preparing ammonia-adsorbing plant fibers: placing plant fibers in a first reaction vessel, introducing ammonia, and placing the fibers at 20° C. to 25° C. and 0.2 MPa to 0.5 MPa for 3 to 7 hours to obtain ammonia-adsorbing plant fibers, wherein the plant fibers include one or more of kapok fibers, bamboo fibers, coconut shell fibers, jute fibers, flax fibers, palm fibers, straw fibers, and reed fibers; (2) In situ synthesis of fatty acid amide with plant fiber as carrier: Add fatty acid and catalyst into a second reaction vessel, raise the temperature to 100°C-120°C, then add the plant fiber adsorbing ammonia described in step (1), stir and react at 0.3MPa-0.5MPa and 170°C-180°C for 4 hours-8 hours to obtain fatty acid amide with plant fiber as carrier, wherein the fatty acid includes an unsaturated hydrocarbon chain, and the number of carbon atoms in the unsaturated hydrocarbon chain is 18-22.

2. The scratch-resistant polypropylene material for automobile interior according to claim 1, characterized in that: In step (1), the plant fiber is pre-treated, and the pre-treatment is to immerse the plant fiber in ethanol for cleaning and removing impurities, and then wash it with deionized water and place it at a temperature of 80°C to 120°C for drying for 3 hours to 5 hours.

3. The scratch-resistant polypropylene material for automobile interior according to claim 1, characterized in that: The plant fiber includes one or more of kapok fiber, bamboo fiber and jute fiber.

4. The scratch-resistant polypropylene material for automobile interior according to claim 3, characterized in that: The plant fibers include kapok fibers and bamboo fibers, and the mass ratio of the kapok fibers to the bamboo fibers is 1:

1.

5. The scratch-resistant polypropylene material for automobile interior according to claim 1, characterized in that: The number of carbon atoms in the unsaturated hydrocarbon chain is 20-22.

6. The scratch-resistant polypropylene material for automobile interior according to claim 1, characterized in that: The polypropylene resin includes a first polypropylene resin and a second polypropylene resin, wherein the first polypropylene resin and the second polypropylene resin are one or more of homopolymer polypropylene, random copolymer polypropylene or block copolymer polypropylene; wherein the melt index of the first polypropylene resin at 230° C. and 2.16 kg is 50-100 g / 10 min, and the melt index of the second polypropylene resin at 230° C. and 2.16 kg is 0.5-35 g / 10 min.

7. The scratch-resistant polypropylene material for automobile interior according to claim 6, characterized in that: In the polypropylene resin, the mass ratio of the first polypropylene resin to the second polypropylene resin is 3:7-7:

3.

8. The scratch-resistant polypropylene material for automobile interior according to claim 1, characterized in that: The inorganic filler includes one or more of talc and wollastonite; and / or, The catalyst includes one or more of tetraisopropyl titanate, tetra-n-butyl titanate and tetra-n-propyl zirconate.

9. The scratch-resistant polypropylene material for automobile interior according to claim 1, characterized in that: The antioxidant comprises a hindered phenol primary antioxidant 1010 and a phosphite secondary antioxidant 168, wherein the mass ratio of the antioxidant 1010 to the antioxidant 168 is 2:1; and / or, The dispersant includes ethylene bisstearamide.

10. A method for preparing the scratch-resistant polypropylene material for automobile interior according to any one of claims 1 to 9, characterized in that: At least the following steps are included: Polypropylene resin, inorganic filler, antioxidant and dispersant are mixed according to the mass ratio and added to the main feeding port of the twin-screw extruder, and the modified scratch-resistant agent is added to the side feeding port of the twin-screw extruder. The temperature of each zone of the twin-screw extruder is 180°C-220°C. After extrusion and drying, the scratch-resistant polypropylene material for automotive interior is obtained.