Anti-yellowing automotive interior composite material and preparation method thereof

Abstract

The invention discloses an anti-yellowing automotive interior composite material and a preparation method thereof, belongs to the technical field of composite material preparation, and aims to solve the technical problem that the anti-yellowing performance and flame retardant performance of an automotive interior material in the prior art need to be further improved. The material specifically comprises the following components in parts by weight: 50-60 parts of modified polystyrene, 20-30 parts of elastic silicon foam and 16-25 parts of auxiliary materials, according to the invention, fluorine group-inlaid and double-bond-terminated long-chain polysiloxane is constructed, the long-chain polysiloxane can participate in a free radical addition reaction so as to obtain modified polystyrene, on the other hand, modified polysiloxane is obtained through phosphorus-hydrogen addition and in-situ generation, and further, the modified polysiloxane and tetramethyl orthosilicate are subjected to a demethanation reaction so as to obtain the modified polystyrene. And melting and extruding the modified polystyrene, the elastic silicon foam and auxiliary materials into a mold to obtain the composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material preparation, and in particular to an anti-yellowing composite material for automobile interior decoration and a preparation method thereof. Background Art

[0002] Anti-yellowing composite materials for automotive interiors have continued to improve with the development of the automotive industry and increasing consumer demand for aesthetics and durability. Early materials such as polyvinyl chloride and styrene-butadiene rubber were susceptible to ultraviolet rays and thermal oxidation, and showed yellowing and brittleness after long-term use. To improve anti-yellowing performance, materials engineers introduced additives such as UV absorbers, antioxidants, and thermal stabilizers, and developed higher-performing substrates such as polycarbonate and polystyrene. In addition, the addition of nanomaterials and multi-layer co-extrusion technology have significantly improved the weather resistance and mechanical strength of composite materials. Overall, anti-yellowing automotive interior materials are rapidly developing in the direction of environmental protection, high performance, and lightweight.

[0003] For example, the prior art CN104098844B discloses a yellowing-resistant PP / HDPE plastic for automotive interior parts and a preparation method thereof, which specifically comprises the following components in parts by weight: 100 parts of polypropylene, 20-30 parts of high-density polyethylene, 10-20 parts of ethylene propylene diene monomer rubber, 1-3 parts of 3-aminopropyltriethoxysilane, and 0.5-1.5 parts of an anti-yellowing agent. The raw materials are weighed according to the ratio, mixed evenly, melt-kneaded, extruded and granulated to obtain the plastic. The anti-yellowing agent is composed of the following components in parts by weight: 20-30 parts of bis(octadecyl)thiodipropionate, 20-30 parts of hexamethylphosphoric acid triamide, 20-30 parts of N-(ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidine, and 20-30 parts of titanium dioxide. The plastic has good yellowing resistance and can be easily processed into automotive interior parts of various shapes by injection molding.

[0004] However, the above invention only mixes anti-ultraviolet materials to obtain an anti-yellowing agent, which is then mixed with the material and melt-extruded to obtain a yellowing-resistant plastic. However, due to the lack of a porous light-scattering structure, ultraviolet rays can penetrate more deeply, accelerating the breakage and oxidation of the photodegradation chain, thereby causing discoloration. The material also lacks a low-density heat dissipation network, allowing faster diffusion of heat and oxygen, thereby intensifying combustion. The lack of a strong carbonization mechanism further weakens the thermal insulation, making it easier for flames to spread. At the same time, the lack of a porous framework for absorbing energy will concentrate mechanical stress, promoting crack formation and surface wear, resulting in the need for further improvement in the composite performance of the material. Summary of the Invention

[0005] The purpose of the present invention is to provide a yellowing-resistant automotive interior composite material and a preparation method thereof, so as to solve the technical problem in the prior art that the yellowing-resistant and flame-retardant properties of automotive interior materials need to be further improved.

[0006] The object of the present invention can be achieved by the following technical solution: an anti-yellowing automotive interior composite material, comprising the following principle components in parts by weight: 50-60 parts of modified polystyrene, 20-30 parts of elastic silicone foam and 16-25 parts of auxiliary materials; The modified polystyrene, 2,2-(4,4-distyryl)bisbenzoxazole and long-chain polysiloxane are prepared by free radical addition reaction; The preparation method of the elastic silicone foam comprises the following steps: adding modified polysiloxane and trispentafluorophenyl borane into a reaction kettle, stirring at room temperature for 5-8 minutes, adding methyl orthosilicate into the reaction kettle, stirring at room temperature for 1-2 minutes, and then quickly transferring the mixture into a mold, transferring the mold into an insulation box at a temperature of 50-70°C, carrying out insulation reaction for 20-30 minutes, and performing post-processing to obtain the elastic silicone foam.

[0007] The reaction formula for preparing elastic silicone foam is:

[0008] The reaction principle for preparing elastic silicone foam is as follows: modified polysiloxane with silicon hydrogen groups and tris(pentafluorophenyl)borane are mixed at room temperature to activate the silicon hydrogen bond, and then methyl orthosilicate is added as a cross-linking agent. The silicon methyl groups react with silicon hydrogen groups under the promotion of heating and catalyst, eliminating methane and forming cross-linked siloxane chain segments, thereby forming a three-dimensional organic silicone network, and finally preparing elastic silicone foam through foaming.

[0009] Furthermore, the auxiliary material includes the following raw materials in parts by weight: 10-15 parts of filler, 5-8 parts of toughening agent, 0.5-1 part of anti-ultraviolet agent and 0.5-1 part of heat stabilizer, wherein the filler is one or more of white carbon black and calcium carbonate; the toughening agent is styrene-butadiene rubber; the anti-ultraviolet agent is one or both of 2,4-dihydroxybenzophenone and 2-hydroxy-4-n-octyloxybenzophenone; and the heat stabilizer is one or both of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester and tris(2,4-di-tert-butylphenyl)phosphite.

[0010] Furthermore, in the process of preparing elastic silicone foam, the usage ratio of modified polysiloxane, trispentafluorophenylborane and methyl orthosilicate is 6-8g:0.3-0.5g:4-5g, and the post-processing includes: after the reaction is completed, demolding, and processing the foam material into a spherical structure with a diameter of 2mm to obtain elastic silicone foam.

[0011] Furthermore, the preparation method of the modified polysiloxane comprises the following steps: A1. Add o-xylene and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to a reactor, raise the reactor temperature to 70-80° C., keep stirring for 10-12 minutes, then add long-chain polysiloxane to the reactor, continue stirring for 5-8 minutes, then add a catalyst to the reactor, keep stirring for 40-60 minutes, and perform post-processing to obtain a flame-retardant polysiloxane. The reaction equation for preparing flame retardant polysiloxane is:

[0012] Where: .

[0013] The reaction principle for preparing flame-retardant polysiloxane is as follows: under heating conditions and the promotion of a catalyst, the silicon-hydrogen bond on 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the carbon-carbon double bond terminated by the long-chain polysiloxane undergo silicon-hydrogenation, and finally flame-retardant polysiloxane is prepared.

[0014] A2. Add titanium tert-butoxide and acetic acid to a low-temperature ultrasonic instrument. After the temperature of the low-temperature ultrasonic instrument is reduced to 0°C, add the composite liquid dropwise to the low-temperature ultrasonic instrument. After the addition is completed within 10-20 minutes, keep the temperature and ultrasonicate for 30-40 minutes, and then post-treat to obtain modified polysiloxane.

[0015] The reaction principle for preparing modified polysiloxane is as follows: tert-butyl titanate is a titanium alcohol, which is combined with acetic acid in a low-temperature ultrasonic instrument at 0°C to control the reaction rate and prevent rapid hydrolysis. Acetic acid acts as a chelating agent to stabilize titanate by forming a titanium acetate complex, thereby adjusting the reactivity of the titanium precursor. Under ultrasonic conditions, the mixture is hydrolyzed, where water reacts with the titanium complex to form titanium hydroxyl groups. These groups then condense to form titanium oxygen bonds and produce titanium dioxide particles, which are anchored to the polysiloxane to prepare modified polysiloxane.

[0016] Furthermore, in step A1, the amount ratio of o-xylene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, long-chain polysiloxane and catalyst is 30-32 mL: 1-2 g: 8-10 g: 0.1-0.2 g, wherein the catalyst is tris(triphenylphosphine)carbonylruthenium (II) hydrochloride, and the post-treatment includes: after the reactor is cooled to room temperature, the reaction solution is added to a rotary evaporator with a salt bath temperature of 80-100 ° C, and distilled under reduced pressure until no liquid is extracted to obtain a flame retardant polysiloxane; Furthermore, in step A2, the amount ratio of titanium tert-butoxide, acetic acid and composite liquid is 0.3-0.5g:0.1g:10mL, wherein the composite liquid is a mixture of flame retardant polysiloxane, o-xylene, n-butanol and deionized water in an amount ratio of 1-2g:5mL:5mL:1mL, and the post-treatment includes: after the reactor is cooled to room temperature, the reaction liquid is added to a rotary evaporator with a salt bath temperature of 80-100°C, and distilled under reduced pressure until no liquid is extracted to obtain modified polysiloxane.

[0017] Furthermore, the preparation method of the long-chain polysiloxane comprises the following steps: B1. Add 1,3,5,7-tetramethylcyclotetrasiloxane, trifluoropropylmethylcyclotrisiloxane and o-xylene to the mold, transfer the mold to a vacuum drying oven, and vacuum dehydrate for 40-60 minutes to obtain a reaction precursor solution; B2. Transfer the reaction precursor solution to a reactor. After the temperature of the reactor is raised to 100-120° C., add a catalyst to the reactor and keep the temperature for 4-5 hours. Then, add tetramethyldivinyldisiloxane to the reactor and keep the temperature for 2-3 hours. After post-treatment, a long-chain polysiloxane is obtained.

[0018] The reaction equation for preparing long-chain polysiloxane is:

[0019] Where: .

[0020] The reaction principle for preparing long-chain polysiloxanes is as follows: 1,3,5,7-tetramethylcyclotetrasiloxane and 3,3,3-trifluoropropylmethylcyclotrisiloxane are mixed with o-xylene, and then vacuum dehydrated to remove moisture, ensuring an anhydrous environment and preventing side reactions and hydrolysis of the siloxane bonds. In the subsequent reaction, the mixture is heated to activate a strong base catalyst to promote ring-opening polymerization. The siloxane ring opens under catalytic conditions, allowing the polysiloxane chain to extend linearly through nucleophilic erosion and condensation. Finally, tetramethyldivinyldisiloxane is added as a capping agent to react with the terminal silanol group to terminate chain growth and introduce vinyl groups, thereby preparing long-chain polysiloxanes.

[0021] Furthermore, in step B1, the ratio of 1,3,5,7-tetramethylcyclotetrasiloxane, trifluoropropylmethylcyclotrisiloxane and o-xylene is 3-5 g:6-7 g:20-30 mL, wherein the temperature of the vacuum drying oven is 60° C. and the vacuum degree is -0.1 MPa; Furthermore, in step B2, the amount ratio of the reaction precursor liquid, the catalyst and tetramethyldivinyldisiloxane is 20-30mL:0.1-0.3g:1-2g, wherein the catalyst is one or both of sodium hydroxide and potassium hydroxide, and the post-treatment includes: after the reactor is cooled to room temperature, the reaction liquid is added to a rotary evaporator with a salt bath temperature of 80-100°C, and distilled under reduced pressure until no liquid is extracted to obtain a long-chain polysiloxane.

[0022] Furthermore, the preparation method of modified polystyrene includes the following steps: adding styrene, 2,2-(4,4-diphenylethylene)bisbenzoxazole and o-xylene to a reactor, stirring at room temperature for 10-12 minutes, raising the temperature of the reactor to 70-80°C, adding azobisisobutyronitrile to the reactor, keeping the temperature for reaction for 40-60 minutes, adding long-chain polysiloxane to the reactor, continuing the reaction for 20-30 minutes, and post-treating to obtain modified polystyrene.

[0023] The reaction equation for preparing modified polystyrene is:

[0024] Where: ; .

[0025] The reaction principle for preparing modified polystyrene is as follows: after styrene, 2,2-(4,4-diphenylethylene)bisbenzoxazole and o-xylene are mixed in a reactor, the initiator azobisisobutyronitrile is activated by heating to thermally decompose and generate free radicals. The free radicals initiate polymerization by attacking the styrene groups to form a continuously growing polymer chain. At the same time, the vinyl group of 2,2-(4,4-diphenylethylene)bisbenzoxazole participates in it, integrating its fluorescent whitening properties into the polymer backbone. The addition of long-chain polysiloxane and its reactive vinyl end groups enables it to be grafted onto the continuously growing polymer chain through free radical addition, thereby preparing modified polystyrene.

[0026] Furthermore, in the process of preparing modified polystyrene, the amount ratio of styrene, 2,2-(4,4-distyryl)bisbenzoxazole, o-xylene, azobisisobutyronitrile and long-chain polysiloxane is 6-8g:2-3g:40-50mL:0.2g:2-3g, and the post-treatment includes: after the reactor is cooled to room temperature, the reaction liquid is added to a rotary evaporator with a salt bath temperature of 80-100°C, and reduced pressure distillation is carried out until no liquid is extracted to obtain modified polystyrene.

[0027] The present invention also provides a method for preparing a yellowing-resistant automotive interior composite material, comprising adding modified polystyrene, elastic silicone foam, filler, toughening agent, UV inhibitor and heat stabilizer into a twin-screw extruder, and melt-extruding the mixture into a mold to obtain the composite material.

[0028] Furthermore, the temperatures of the eight temperature zones of the twin-screw extruder from the feed port toward the discharge port are 180°C, 185°C, 185°C, 190°C, 195°C, 200°C, 210°C, and 210°C, respectively. The main engine speed of the twin-screw extruder is 120-160rpm, and the pressure is 80-120bar.

[0029] The present invention has the following beneficial effects: 1. The present invention incorporates a large number of fluorine groups into long-chain polysiloxane through a polymerization reaction, thereby improving the chemical inertness of the material and effectively reducing oxidative degradation caused by ultraviolet radiation. At the same time, the modified polystyrene embedded with a fluorescent whitening agent absorbs ultraviolet rays and converts them into visible light, thereby reducing the tendency to yellowing. The introduction of a phosphate structure enhances the thermal stability of the polysiloxane, providing strong protection against heat-accelerated aging that may exacerbate discoloration. Titanium dioxide particles complement this system by reflecting and scattering ultraviolet radiation, significantly reducing the photodegradation process and maintaining color fidelity. In addition, the spherical porous structure of the elastic silicone foam enhances this defense capability by creating complex light scattering pathways, reducing ultraviolet penetration and the resulting yellowing. The synergistic combination of fluorine stability, photoconversion of the whitening agent, thermal enhancement of the phosphate, ultraviolet deflection of titanium dioxide, and scattering of the foam ensures long-lasting color stability under long-term exposure to light and environmental pressure.

[0030] 2. The porous structure of the elastic silicone foam prepared by the present invention serves as the initial line of defense. Its low-density, high-surface-area network effectively diffuses heat energy and limits oxygen diffusion, thereby preventing the ignition and spread of flames. Within the polysiloxane framework, the phosphate groups help the composite material form a thermally stable carbon-rich barrier during combustion, protecting the material from the invasion of heat and oxygen, while releasing non-combustible gases to dilute the oxygen concentration and destroy the propagation of flames. At the same time, the fluorine-containing long-chain polysiloxane forms a thermally stable and dense flame-retardant layer, which minimizes heat transfer and inhibits the release of flammable volatiles, enhancing flame resistance. The flame retardancy of the material is significantly improved by utilizing the foam's ability to limit the diffusion of heat and oxygen, the carbonization and gas dilution mechanism of the phosphate groups, and the flame-retardant layer formed by the polysiloxane.

[0031] 3. The present invention utilizes the spherical porous structure of elastic silicone foam as an energy absorption frame. Its low density and high surface area network can disperse mechanical stress and inhibit the expansion of cracks under abrasive force or impact force, thereby reducing surface wear and improving impact toughness. The polysiloxane chain has the characteristics of high tensile strength and flexibility, and can provide a durable main chain that resists deformation and maintains structural integrity under mechanical stress, thereby effectively reducing material loss caused by wear and impact-related fractures. At the same time, the fluorine groups incorporated into the polysiloxane reduce the surface friction coefficient, minimize friction and wear by promoting smoother surface interactions and reducing wear under repeated contact, and utilize titanium dioxide particles to enhance surface hardness, prevent scratches and material erosion, and further improve wear resistance. Ultimately, through the synergistic combination of the foam's stress dispersion and energy absorption capacity, the flexibility of the polysiloxane chain segments, the effect of the fluorine groups on the surface energy of the material, and the surface hardening effect of titanium dioxide, the wear resistance and impact resistance of the composite material are significantly improved. DETAILED DESCRIPTION

[0032] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] The white carbon black used in the present invention was purchased from Shanghai Jizhi Biochemical Technology Co., Ltd., with the product number S23920-1kg; The styrene-butadiene rubber used in the present invention was purchased from Shanghai Jiadeer Chemical Technology Co., Ltd. with the product number JD191122165504.

[0034] Example 1 This embodiment provides a method for preparing a long-chain polysiloxane for use in preparing a yellowing-resistant automotive interior composite material, comprising the following steps: Step ①, prepare reaction precursor solution Weigh: 60.0 g of 1,3,5,7-tetramethylcyclotetrasiloxane, 120.0 g of trifluoropropylmethylcyclotrisiloxane and 400.0 mL of o-xylene are added to the mold, and the mold is transferred to a vacuum drying oven. The temperature of the vacuum drying oven is set to 60°C, the vacuum degree is set to -0.1 MPa, and vacuum dehydration is performed for 40 minutes to obtain a reaction precursor solution.

[0035] Step 2: Preparation of long-chain polysiloxane Weigh: 400.0 mL of the reaction precursor solution was transferred to the reactor. After the temperature of the reactor was raised to 100° C., 2.0 g of potassium hydroxide was added to the reactor. After the reaction was kept warm for 4 hours, 20.0 g of tetramethyldivinyldisiloxane was added to the reactor. The reaction was kept warm for 2 hours. After the reactor was cooled to room temperature, the reaction solution was added to a rotary evaporator with a salt bath temperature of 80° C. and distilled under reduced pressure until no liquid was extracted to obtain a long-chain polysiloxane.

[0036] Example 2 This embodiment provides a method for preparing a long-chain polysiloxane for use in preparing a yellowing-resistant automotive interior composite material, comprising the following steps: Step ①, prepare reaction precursor solution Weigh: 100.0 g of 1,3,5,7-tetramethylcyclotetrasiloxane, 140.0 g of trifluoropropylmethylcyclotrisiloxane and 600.0 mL of o-xylene are added to the mold, and the mold is transferred to a vacuum drying oven. The temperature of the vacuum drying oven is set to 60°C, the vacuum degree is set to -0.1 MPa, and vacuum dehydration is performed for 60 minutes to obtain a reaction precursor solution.

[0037] Step 2: Preparation of long-chain polysiloxane Weigh: 600.0 mL of the reaction precursor solution was transferred to the reactor. After the temperature of the reactor was raised to 120°C, 6.0 g of potassium hydroxide was added to the reactor. After the reaction was kept warm for 5 hours, 40.0 g of tetramethyldivinyldisiloxane was added to the reactor. The reaction was kept warm for 3 hours. After the reactor was cooled to room temperature, the reaction solution was added to a rotary evaporator with a salt bath temperature of 100°C, and distilled under reduced pressure until no liquid was extracted to obtain a long-chain polysiloxane.

[0038] Example 3 This embodiment provides a method for preparing a long-chain polysiloxane for use in preparing a yellowing-resistant automotive interior composite material, comprising the following steps: Step ①, prepare reaction precursor solution Weigh 80.0 g of 1,3,5,7-tetramethylcyclotetrasiloxane, 128.0 g of trifluoropropylmethylcyclotrisiloxane and 540.0 mL of o-xylene and add them to the mold. Transfer the mold to a vacuum drying oven, set the temperature of the vacuum drying oven to 60°C, the vacuum degree to -0.1 MPa, and vacuum dehydrate for 50 minutes to obtain a reaction precursor solution.

[0039] Step 2: Preparation of long-chain polysiloxane Weigh: 540.0 mL of the reaction precursor solution was transferred to the reactor. After the temperature of the reactor was raised to 120°C, 4.0 g of potassium hydroxide was added to the reactor. After the reaction was kept warm for 5 hours, 32.0 g of tetramethyldivinyldisiloxane was added to the reactor. The reaction was kept warm for 3 hours. After the reactor was cooled to room temperature, the reaction solution was added to a rotary evaporator with a salt bath temperature of 90°C, and distilled under reduced pressure until no liquid was extracted to obtain a long-chain polysiloxane.

[0040] Example 4 This embodiment provides a method for preparing an elastic silicone foam for use in preparing a yellowing-resistant automotive interior composite material, comprising the following steps: Step I: Preparation of flame retardant polysiloxane Weigh: 300.0mL o-xylene and 10.0g 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were added to the reactor, the reactor temperature was raised to 70°C, and after stirring for 10 minutes, 80.0g of the long-chain polysiloxane prepared in Example 1 was added to the reactor. After stirring for 5 minutes, 1.0g of tris(triphenylphosphine)carbonylruthenium (II) hydrochloride was added to the reactor, and the mixture was stirred for 40 minutes. After the reactor was cooled to room temperature, the reaction solution was added to a rotary evaporator with a salt bath temperature of 80°C and distilled under reduced pressure until no liquid was extracted to obtain a flame retardant polysiloxane.

[0041] Step II: Preparation of modified polysiloxane Weigh 80.0 g of flame retardant polysiloxane, 200.0 mL of o-xylene, 200.0 mL of n-butanol, and 40.0 mL of deionized water and mix to obtain a composite solution; Weigh 6.0 g of titanium tert-butoxide and 2.0 g of acetic acid and add them to a low-temperature ultrasonic instrument. After the temperature of the low-temperature ultrasonic instrument is lowered to 0°C, 200.0 mL of the composite liquid is added dropwise to the low-temperature ultrasonic instrument. After the addition is completed within 10 minutes, the temperature is kept warm and ultrasonicated for 30 minutes. After the reactor is cooled to room temperature, the reaction liquid is added to a rotary evaporator with a salt bath temperature of 80°C and distilled under reduced pressure until no liquid is extracted to obtain a modified polysiloxane.

[0042] Step III: Preparation of elastic silicone foam Weigh: 60.0g of modified polysiloxane and 3.0g of trispentafluorophenylborane are added to the reactor, stirred at room temperature for 5 minutes, then 40.0g of methyl orthosilicate is added to the reactor, stirred at room temperature for 1 minute, and then quickly transferred to a mold. The mold is transferred to an insulated box at a temperature of 50°C and kept warm for 20 minutes. After the reaction is completed, demolding is carried out, and the foam material is processed into a spherical structure with a diameter of 2mm to obtain elastic silicone foam.

[0043] Example 5 This embodiment provides a method for preparing an elastic silicone foam for use in preparing a yellowing-resistant automotive interior composite material, comprising the following steps: Step I: Preparation of flame retardant polysiloxane Weigh: 320.0mL o-xylene and 20.0g 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were added to the reactor, the reactor temperature was raised to 80°C, and the mixture was stirred for 12 minutes. Then, 100.0g of the long-chain polysiloxane prepared in Example 2 was added to the reactor. After stirring for 8 minutes, 2.0g of tris(triphenylphosphine)carbonylruthenium (II) hydrochloride was added to the reactor, and the mixture was stirred for 60 minutes. After the reactor was cooled to room temperature, the reaction solution was added to a rotary evaporator with a salt bath temperature of 100°C and distilled under reduced pressure until no liquid was extracted to obtain a flame retardant polysiloxane.

[0044] Step II: Preparation of modified polysiloxane Weigh 80.0 g of flame retardant polysiloxane, 200. mL of o-xylene, 200.0 mL of n-butanol, and 40.0 mL of deionized water and mix to obtain a composite solution; Weigh 10.0 g of titanium tert-butoxide and 2.0 g of acetic acid and add them to a low-temperature ultrasonic instrument. After the temperature of the low-temperature ultrasonic instrument is lowered to 0°C, 200.0 mL of the composite liquid is added dropwise to the low-temperature ultrasonic instrument. After the addition is completed within 20 minutes, the temperature is kept and ultrasonicated for 40 minutes. After the reactor is cooled to room temperature, the reaction liquid is added to a rotary evaporator with a salt bath temperature of 100°C and distilled under reduced pressure until no liquid is extracted to obtain a modified polysiloxane.

[0045] Step III: Preparation of elastic silicone foam Weigh: 65.0g of modified polysiloxane and 4.0g of trispentafluorophenylborane are added to the reactor, stirred at room temperature for 8 minutes, then 50.0g of methyl orthosilicate is added to the reactor, stirred at room temperature for 2 minutes, and then quickly transferred to a mold. The mold is transferred to an insulated box at a temperature of 70°C and kept warm for 30 minutes. After the reaction is completed, demolding is carried out, and the foam material is processed into a spherical structure with a diameter of 2mm to obtain elastic silicone foam.

[0046] Example 6 This embodiment provides a method for preparing an elastic silicone foam for use in preparing a yellowing-resistant automotive interior composite material, comprising the following steps: Step I: Preparation of flame retardant polysiloxane Weigh: 320.0mL o-xylene and 16.0g 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were added to the reactor, the reactor temperature was raised to 72°C, and after stirring for 12 minutes, 90.0g of the long-chain polysiloxane prepared in Example 3 was added to the reactor. After stirring for 6 minutes, 1.6g of tris(triphenylphosphine)carbonylruthenium (II) chloride was added to the reactor, and the mixture was stirred for 50 minutes. After the reactor was cooled to room temperature, the reaction solution was added to a rotary evaporator with a salt bath temperature of 90°C and distilled under reduced pressure until no liquid was extracted to obtain a flame retardant polysiloxane.

[0047] Step II: Preparation of modified polysiloxane Weigh 80.0 g of flame retardant polysiloxane, 200.0 mL of o-xylene, 200.0 mL of n-butanol, and 40.0 mL of deionized water and mix to obtain a composite solution; 8.0 g of titanium tert-butoxide and 2.0 g of acetic acid were weighed and added to a low-temperature ultrasonic instrument. After the temperature of the low-temperature ultrasonic instrument was lowered to 0°C, 200.0 mL of the composite liquid was added dropwise to the low-temperature ultrasonic instrument. After the addition was completed within 16 minutes, the temperature was kept warm and ultrasonicated for 35 minutes. After the reactor was cooled to room temperature, the reaction liquid was added to a rotary evaporator with a salt bath temperature of 90°C and distilled under reduced pressure until no liquid was extracted to obtain a modified polysiloxane.

[0048] Step III: Preparation of elastic silicone foam Weigh: 60.0g modified polysiloxane and 4.0g trispentafluorophenylborane are added to the reactor, stirred at room temperature for 6 minutes, then 45.0g methyl orthosilicate is added to the reactor, stirred at room temperature for 2 minutes, and then quickly transferred to a mold. The mold is transferred to an insulated box at a temperature of 60°C and kept warm for 24 minutes. After the reaction is completed, demolding is carried out, and the foam material is processed into a spherical structure with a diameter of 2mm to obtain elastic silicone foam.

[0049] Example 7 This embodiment provides a method for preparing a yellowing-resistant automotive interior composite material, comprising the following steps: Step 1: Preparation of modified polystyrene Weigh: 60.0 g of styrene, 20.0 g of 2,2-(4,4-diphenylethylene)bisbenzoxazole and 400.0 mL of o-xylene were added to a reactor and stirred at room temperature for 10 minutes. The temperature of the reactor was raised to 70°C, 2.0 g of azobisisobutyronitrile was added to the reactor, and the reaction was kept warm for 40 minutes. Then, 20.0 g of the long-chain polysiloxane prepared in Example 1 was added to the reactor, and the reaction was continued for 20 minutes. After the reactor was cooled to room temperature, the reaction solution was added to a rotary evaporator with a salt bath temperature of 80°C and distilled under reduced pressure until no liquid was extracted to obtain modified polystyrene.

[0050] Step 2: Preparation of composite materials Weigh: 50 parts of modified polystyrene, 20 parts of the elastic silicone foam prepared in Example 4, 10 parts of white carbon black, 5 parts of styrene-butadiene rubber, 0.5 parts of 2,4-dihydroxybenzophenone and 0.5 parts of tris(2,4-di-tert-butylphenyl)phosphite and add them to a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed port toward the discharge port are 180°C, 185°C, 185°C, 190°C, 195°C, 200°C, 210°C, and 210°C, respectively. The main engine speed of the twin-screw extruder is 120 rpm, the pressure is 80 bar, and the extruder is melt-extruded into a mold to obtain a composite material.

[0051] Example 8 This embodiment provides a method for preparing a yellowing-resistant automotive interior composite material, comprising the following steps: Step 1: Preparation of modified polystyrene Weigh: 80.0g of styrene, 30.0g of 2,2-(4,4-diphenylethylene)bisbenzoxazole and 500.0mL of o-xylene were added to the reactor and stirred at room temperature for 12min. The temperature of the reactor was raised to 80°C, and 2.0g of azobisisobutyronitrile was added to the reactor. After the reaction was kept warm for 60min, 30.0g of the long-chain polysiloxane prepared in Example 2 was added to the reactor. The reaction was continued for 30min and the reactor was cooled to room temperature. The reaction solution was added to a rotary evaporator with a salt bath temperature of 100°C and distilled under reduced pressure until no liquid was extracted to obtain modified polystyrene.

[0052] Step 2: Preparation of composite materials Weigh: 60 parts of modified polystyrene, 30 parts of the elastic silicone foam prepared in Example 5, 15 parts of white carbon black, 8 parts of styrene-butadiene rubber, 1 part of 2,4-dihydroxybenzophenone and 1 part of tris(2,4-di-tert-butylphenyl)phosphite and add them to a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed port toward the discharge port are 180°C, 185°C, 185°C, 190°C, 195°C, 200°C, 210°C, and 210°C, respectively. The main engine speed of the twin-screw extruder is 160 rpm, the pressure is 120 bar, and the extruder is melt-extruded into a mold to obtain a composite material.

[0053] Example 9 This embodiment provides a method for preparing a yellowing-resistant automotive interior composite material, comprising the following steps: Step 1: Preparation of modified polystyrene Weigh: 72.0 g of styrene, 24.0 g of 2,2-(4,4-diphenylethylene)bisbenzoxazole and 450.0 mL of o-xylene were added to the reactor and stirred at room temperature for 12 minutes. The temperature of the reactor was raised to 75°C, and 2.0 g of azobisisobutyronitrile was added to the reactor. After the reaction was kept warm for 50 minutes, 25.0 g of the long-chain polysiloxane prepared in Example 3 was added to the reactor. The reaction was continued for 25 minutes and the reactor was cooled to room temperature. The reaction solution was added to a rotary evaporator with a salt bath temperature of 90°C and distilled under reduced pressure until no liquid was extracted to obtain modified polystyrene.

[0054] Step 2: Preparation of composite materials Weigh: 54 parts of modified polystyrene, 24 parts of the elastic silicone foam prepared in Example 6, 12 parts of white carbon black, 6 parts of styrene-butadiene rubber, 0.8 parts of 2,4-dihydroxybenzophenone and 0.8 parts of tris(2,4-di-tert-butylphenyl)phosphite and add them to a twin-screw extruder. The temperatures of the eight temperature zones of the twin-screw extruder from the feed port toward the discharge port are 180°C, 185°C, 185°C, 190°C, 195°C, 200°C, 210°C, and 210°C, respectively. The main engine speed of the twin-screw extruder is 150 rpm, the pressure is 100 bar, and the extruder is melt-extruded into a mold to obtain a composite material.

[0055] Comparative Example 1 The difference between this comparative example and Example 9 is that, in the preparation process of the elastic silicone foam used in this comparative example, step III is omitted, and modified polysiloxane of equal quality is used to replace the elastic silicone foam.

[0056] Comparative Example 2 The difference between this comparative example and Example 9 is that, in the process of preparing the composite material, the elastic silicone foam is omitted in this comparative example.

[0057] Comparative Example 3 The difference between this comparative example and Example 9 is that in this comparative example, the use of long-chain polysiloxane is omitted during the preparation of modified polystyrene.

[0058] Performance testing: The yellowing resistance of the composite materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested with reference to the standard GB / T 41793-2022 "Test methods for artificial leather and synthetic leather - Determination of potential phenolic yellowing". The vertical burning rating of the composite materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested with reference to the standard GB / T 2408-2021 “Determination of combustion properties of plastics—Horizontal and vertical methods”; The limiting oxygen index of the composite materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested with reference to the standard GB / T 26526-2011 "Determination of combustion behavior of plastics by oxygen index method Part 2: Room temperature test"; The volume wear of the composite materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested with reference to the standard GB / T 9867-2008 "Determination of wear resistance of vulcanized or thermoplastic rubber (rotating roller abrader method)". The Izod impact strength of the composite materials prepared in Examples 7-9 and Comparative Examples 1-3 was tested with reference to the standard GB / T 1843-2008 “Determination of Izod impact strength of plastics”. Specific data are shown in Table 1.

[0059] Table 1 - Performance test data of each sample

[0060] Data Analysis: After comparing and analyzing the data in Table 1, it can be found that the composite material prepared by the present invention has a yellowing resistance grade of 5, a vertical burning grade of V-0, a limiting oxygen index of 39.1%, a volume abrasion loss of 39.1, and an Izod impact strength of 54 kJ·m-2, all of which are better than the comparative example; The yellowing resistance of the composite materials prepared in Example 9 and Comparative Examples 1-3 is significantly weaker than that of the composite material prepared in Example 9, indicating that: In Comparative Example 1, using modified polysiloxane instead of elastic silicone foam of equal mass reduces yellowing resistance. The foam's spherical porous structure scatters UV rays, reducing penetration and photodegradation. Denser polysiloxane cannot replicate this function, leading to increased UV-induced oxidative degradation and accelerated yellowing. Although polysiloxane retains fluorine groups for chemical stability and phosphate structures for thermal protection, the lack of light scattering pathways in the foam weakens the synergistic UV-blocking effect with titanium dioxide and fluorescent brighteners. The denser polysiloxane structure also restricts the dispersion of additives, reducing the brightener's UV absorption and conversion efficiency. In Comparative Example 2, eliminating the use of elastic silicone foam significantly weakens yellowing resistance. The spherical porous structure of the foam scatters UV light, reducing its penetration and subsequent photodegradation. Without the foam structure, UV light penetrates deeply into the material, accelerating oxidative degradation and yellowing. Although the fluorine groups in the polysiloxane and the fluorescent brighteners in the polystyrene provide some UV protection, their effectiveness is diminished without the light-scattering and additive-dispersing capabilities of the foam. The lack of a high surface area of the foam also reduces the uniform distribution of the titanium dioxide and brighteners, limiting their ability to block and convert UV light. In Comparative Example 3, the elimination of the use of long-chain polysiloxane in the preparation process of modified polystyrene will weaken the yellowing resistance. The fluorine group of polysiloxane enhances the chemical stability and reduces the ultraviolet-induced oxidative degradation. Therefore, without polysiloxane, the material is more susceptible to photodegradation, thereby accelerating yellowing. Although the fluorescent whitening agent in polystyrene can still absorb and convert ultraviolet rays, its effectiveness will be reduced without the stable matrix of polysiloxane, thereby reducing the dispersion of the phosphoric acid structure and the synergistic effect with titanium dioxide. The light scattering structure of the elastic silicone foam partially reduces the penetration of ultraviolet rays, but cannot completely make up for the decline in anti-yellowing performance caused by the lack of the fluorine protective layer and the silicone segment.

[0061] The flame retardant properties of the composite materials prepared in Example 9 and Comparative Examples 1-3 are significantly weaker than that of the composite material prepared in Example 9, indicating that: In Comparative Example 1, the use of modified polysiloxane instead of elastic silicone foam results in a decrease in the flame retardant properties of the material. This is because the porous structure of the foam restricts the diffusion of heat and oxygen, hindering the generation of flames, while the denser polysiloxane cannot effectively play this role. The high surface area of the foam also ensures the uniform distribution of the flame retardant additive, enhancing the early fire extinguishing ability. Without the foam, this fire extinguishing effect will be affected. Although the polysiloxane retains the phosphate group for carbonization and gas dilution, and retains fluorine for thermal stability, the lack of a low-density network of the foam reduces the heat dissipation and oxygen exhaust efficiency. Compared with the examples, this results in faster flame propagation and weaker thermal insulation. The carbonization ability of the polysiloxane alone cannot compensate for the contribution of the foam to the cohesive flame retardant system, resulting in reduced fire resistance under combustion conditions. Comparative Example 2 lacks elastic silicon, and the foam will seriously affect the flame retardancy. The low-density porous structure of the foam limits the diffusion of heat and oxygen, delaying the generation and spread of flames, which is a role that cannot be compensated by other components. Without the foam, the material lacks an effective initial barrier and cannot achieve faster heat transfer and oxygen acquisition, thereby accelerating combustion. The high surface area of the foam also ensures the uniform dispersion of the flame retardant additive and improves the suppression efficiency, which is lost in this example. Although the phosphate groups and fluorine in the polysiloxane promote the formation and thermal stability of carbides, they cannot completely alleviate the heat dissipation and oxygen-limiting properties of the foam, resulting in weaker carbon insulation and faster flame propagation compared to the examples. The structure of the foam significantly enhances the overall flame retardancy of the composite system. Comparative Example 3 does not contain long-chain polysiloxane in the preparation of modified polystyrene, which reduces the flame retardant properties of the material. The fluorine group of polysiloxane contributes to thermal stability and forms a durable carbonized layer, thereby limiting the transfer of heat and oxygen during combustion. Without this component, the material lacks this strong carbonization ability, resulting in faster heat penetration and flame spread. The phosphate groups still promote the formation of the carbon layer, but without the stabilizing framework of polysiloxane, their effectiveness will be reduced. The porous structure of the elastic silicone foam limits the diffusion of heat and oxygen, but it cannot fully compensate for the effects of polysiloxane on thermal stability and charring.

[0062] The wear resistance and impact resistance of the composite materials prepared in Example 9 and Comparative Examples 1-3 are significantly weaker than those of the composite material prepared in Example 9, indicating that: Comparative Example 1: Replacing the elastic silicone foam with modified polysiloxane weakens wear resistance and impact resistance. This is because the spherical porous structure of the foam can absorb and disperse mechanical stress, reducing crack propagation and surface wear under abrasive or impact forces. The denser polysiloxane lacks this energy absorption capacity, resulting in increased material loss and cracking sensitivity. Although polysiloxane provides strength through its strong chains and fluorine stability, it cannot match the flexibility and stress dissipation properties of the foam. The high surface area of the foam also enhances the dispersion of additives and improves the cohesion of the matrix, which is less effective in polysiloxane alternatives. Therefore, compared with the examples, the material exhibits a higher wear rate and lower toughness under mechanical stress. In Comparative Example 2, the omission of the elastic silicone foam significantly reduced the material's wear resistance and impact resistance. This is because the foam's spherical porous structure can absorb and disperse mechanical stress, preventing crack propagation and surface wear under abrasive or impact forces. Without this structure, the material lacks this energy-absorbing framework, resulting in increased material loss and cracking. In addition, the foam's high surface area also facilitates the uniform dispersion of additives and enhances matrix cohesion. Although the stability of the polysiloxane segments and fluorine groups provides some performance improvements, they cannot replace the flexibility and stress dissipation capabilities of the foam structure. In Comparative Example 3, the elimination of the use of long-chain polysiloxane in the preparation of modified polystyrene will reduce the wear resistance and impact resistance of the material. This is because the strong chains and fluorine groups of polysiloxane provide a strong, flexible matrix that can resist deformation and material loss under mechanical stress. Without this organic segment, the polystyrene matrix is susceptible to cracking caused by impact, resulting in increased wear. The porous structure of the elastic silicone foam can absorb some mechanical stress, but its effectiveness will be limited without the reinforcing main chain of polysiloxane. Titanium dioxide particles can increase the surface hardness, but they cannot fully compensate for the contribution of polysiloxane to the matrix strength and friction reduction. Therefore, compared with the examples, the material exhibits a higher wear rate and lower toughness.

[0063] Finally, it is explained that the present invention uses 1,3,5,7-tetramethylcyclotetrasiloxane and trifluoropropylmethylcyclotrisiloxane as main raw materials, performs a ring-opening reaction under strong base catalysis conditions to fully break the siloxane chain segments, and then uses tetramethyldivinyldisiloxane for end-capping to construct a fluorine group-embedded, double-bond-terminated long-chain polysiloxane; on the one hand, the long-chain polysiloxane can undergo a free radical addition reaction with polystyrene and the fluorescent whitening agent 2,2-(4,4-distyryl)bisbenzoxazole to obtain modified polystyrene; on the other hand, a phosphoric acid structure is introduced by phosphine-hydrogen addition, and then titanium dioxide particles are loaded on the siloxane structure by in situ generation to obtain a modified polysiloxane; further, the modified polysiloxane reacts with methyl orthosilicate through demethanization under heating conditions and the catalysis of a boron catalyst, and finally a spherical elastic silicone foam is prepared by processing, and the modified polystyrene, elastic silicone foam and auxiliary materials are melt-extruded into a mold to obtain a high-performance yellowing-resistant composite material.

[0064] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A yellowing-resistant automotive interior composite material, characterized in that: The invention comprises the following principle components in parts by weight: 50-60 parts of modified polystyrene, 20-30 parts of elastic silicone foam and 16-25 parts of auxiliary materials; The modified polystyrene is prepared by free radical addition reaction of styrene, 2,2-(4,4-distyryl)bisbenzoxazole and long-chain polysiloxane; The preparation method of the elastic silicone foam comprises the following steps: adding modified polysiloxane and trispentafluorophenyl borane into a reaction kettle, stirring at room temperature for 5-8 minutes, adding methyl orthosilicate into the reaction kettle, stirring at room temperature for 1-2 minutes, and then quickly transferring the mixture into a mold, transferring the mold into an insulation box at a temperature of 50-70°C, carrying out insulation reaction for 20-30 minutes, and performing post-processing to obtain the elastic silicone foam.

2. The anti-yellowing composite material for automobile interior decoration according to claim 1, characterized in that: The auxiliary materials include the following raw materials in parts by weight: 10-15 parts of filler, 5-8 parts of toughening agent, 0.5-1 part of anti-ultraviolet agent and 0.5-1 part of heat stabilizer; in the process of preparing elastic silicone foam, the usage ratio of modified polysiloxane, trispentafluorophenyl borane and methyl orthosilicate is 6-8g:0.3-0.5g:4-5g.

3. The anti-yellowing composite material for automobile interior decoration according to claim 1, characterized in that: The preparation method of the modified polysiloxane comprises the following steps: A1. Add o-xylene and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to a reactor, raise the reactor temperature to 70-80° C., keep stirring for 10-12 minutes, then add long-chain polysiloxane to the reactor, continue stirring for 5-8 minutes, then add a catalyst to the reactor, keep stirring for 40-60 minutes, and perform post-processing to obtain a flame-retardant polysiloxane. A2. Add titanium tert-butoxide and acetic acid to a low-temperature ultrasonic instrument. After the temperature of the low-temperature ultrasonic instrument is reduced to 0°C, add the composite liquid dropwise to the low-temperature ultrasonic instrument. After the addition is completed within 10-20 minutes, keep the temperature and ultrasonicate for 30-40 minutes, and then post-treat to obtain modified polysiloxane.

4. The anti-yellowing composite material for automobile interior decoration according to claim 3, characterized in that: In step A1, the amount ratio of o-xylene, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, long-chain polysiloxane and catalyst is 30-32 mL: 1-2 g: 8-10 g: 0.1-0.2 g, wherein the catalyst is tris(triphenylphosphine)carbonylruthenium (II) hydrochloride; in step A2, the amount ratio of titanium tert-butoxide, acetic acid and composite liquid is 0.3-0.5 g: 0.1 g: 10 mL, wherein the composite liquid is a mixture of flame retardant polysiloxane, o-xylene, n-butanol and deionized water in an amount ratio of 1-2 g: 5 mL: 5 mL: 1 mL.

5. The anti-yellowing composite material for automobile interior decoration according to claim 1, characterized in that: The preparation method of the long-chain polysiloxane comprises the following steps: B1. Add 1,3,5,7-tetramethylcyclotetrasiloxane, trifluoropropylmethylcyclotrisiloxane and o-xylene to the mold, transfer the mold to a vacuum drying oven, and vacuum dehydrate for 40-60 minutes to obtain a reaction precursor solution; B2. Transfer the reaction precursor solution to a reactor. After the temperature of the reactor is raised to 100-120° C., add a catalyst to the reactor and keep the temperature for 4-5 hours. Then, add tetramethyldivinyldisiloxane to the reactor and keep the temperature for 2-3 hours. After post-treatment, a long-chain polysiloxane is obtained.

6. The anti-yellowing composite material for automobile interior decoration according to claim 5, characterized in that: In step B1, the amount ratio of the 1,3,5,7-tetramethylcyclotetrasiloxane, trifluoropropylmethylcyclotrisiloxane and o-xylene is 3-5g:6-7g:20-30mL, wherein the temperature of the vacuum drying oven is 60°C and the vacuum degree is -0.1MPa; in step B2, the amount ratio of the reaction precursor solution, the catalyst and tetramethyldivinyldisiloxane is 20-30mL:0.1-0.3g:1-2g, wherein the catalyst is one or both of sodium hydroxide and potassium hydroxide.

7. The anti-yellowing composite material for automobile interior decoration according to claim 1, characterized in that: The preparation method of the modified polystyrene comprises the following steps: adding styrene, 2,2-(4,4-distyryl)bisbenzoxazole and o-xylene into a reactor, stirring at room temperature for 10-12 minutes, raising the temperature of the reactor to 70-80° C., adding azobisisobutyronitrile into the reactor, keeping the temperature for reaction for 40-60 minutes, adding long-chain polysiloxane into the reactor, continuing the reaction for 20-30 minutes, and post-processing to obtain the modified polystyrene.

8. The anti-yellowing composite material for automobile interior decoration according to claim 7, characterized in that: In the process of preparing modified polystyrene, the usage ratio of styrene, 2,2-(4,4-distyryl)bisbenzoxazole, o-xylene, azobisisobutyronitrile and long-chain polysiloxane is 6-8g:2-3g:40-50mL:0.2g:2-3g.

9. A method for preparing the anti-yellowing composite material for automobile interior decoration according to any one of claims 1 to 8, characterized in that: The modified polystyrene, elastic silicone foam, filler, toughening agent, UV inhibitor and heat stabilizer are added into a twin-screw extruder, melt-extruded into a mold, and obtain a composite material.

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