A GMT composite material automotive ceiling and its preparation method

Abstract

The present application belongs to the technical field of automobile accessories, and specifically discloses a GMT composite material automobile roof and a preparation method thereof. The GMT composite material automobile roof comprises a GMT composite sheet layer, a hot melt adhesive layer and a fabric layer, characterized in that the GMT composite sheet layer comprises the following raw materials in parts by weight: 90-100 parts of composite fiber felt, 22-30 parts of modified bamboo fiber, 3-5 parts of tea tree oil, 1-2 parts of sodium tripolyphosphate, 2-4 parts of β-glycerophosphate disodium, 0.5-0.8 parts of lecithin, 15-20 parts of modified talcum powder, 4-6 parts of expandable microsphere foaming agent, and 190-200 parts of deionized water. The GMT composite material automobile roof prepared in the present application has excellent mechanical strength, durability and aging resistance, can provide mechanical protection for components, and extend the service life of the automobile roof.

Description

Technical Field

[0001] The present application relates to the technical field of automobile accessories, and in particular to a GMT composite material automobile roof and a preparation method thereof. Background Art

[0002] The car roof, also known as the roof system or canopy, is a key component of the car's interior. It is connected to the car body roof crossbeams, side panel inner skins, pillars, sun visors, safety handles, interior ceiling lights and other components, and has the functions of heat insulation and thermal insulation, sound insulation and sound absorption, and safety.

[0003] From a structural point of view, the car roof can be divided into a facing layer, an adhesive layer and a frame layer. The facing layer directly faces the passengers and is usually made of fabric, artificial leather, PVC film and other materials; the frame layer provides structural support and is usually made of metal, plastic or composite materials; the adhesive layer is used for the facing layer and the frame layer to make the car roof structure stable.

[0004] For the skeleton layer, PU-based ceiling is usually used, which has the advantages of light weight, wear resistance, sound insulation and noise reduction, high toughness, and not easy to crack or deform. However, under high temperature or long-term exposure to sunlight, the PU substrate may undergo thermal aging, causing the surface to become sticky, which in turn affects the appearance and service life. Summary of the invention

[0005] In order to improve the problem of thermal aging of PU substrates caused by long-term exposure to sunlight, the present application provides a GMT composite material automobile roof and a preparation method thereof.

[0006] The present application provides a GMT composite material automobile roof, which adopts the following technical solution:

[0007] A GMT composite material automobile roof comprises a GMT composite sheet layer, a hot melt adhesive layer and a fabric layer, characterized in that the GMT composite sheet layer comprises the following raw materials, measured in parts by weight: 90-100 parts of composite fiber felt, 22-30 parts of modified bamboo fiber, 3-5 parts of tea tree oil, 1-2 parts of sodium tripolyphosphate, 2-4 parts of β-glycerophosphate disodium, 0.5-0.8 parts of lecithin, 15-20 parts of modified talc, 4-6 parts of expandable microsphere foaming agent, and 190-200 parts of deionized water.

[0008] By adopting the above technical solutions, GMT is a glass fiber mat reinforced thermoplastic composite material. The GMT composite board layer serves as the main structural layer of the car roof. The GMT material is a composite material with a thermoplastic resin as the matrix and a glass fiber mat as the reinforcing skeleton, having the advantages of light weight, toughness, rigidity, impact resistance, and corrosion resistance. The GMT composite board layer plays a supporting and protective role in the car roof, can withstand certain external force impacts, and has good sound absorption performance, which can effectively block the noise transmitted from the car roof into the vehicle and absorb the noise generated inside the vehicle, thus improving the riding comfort of the car.

[0009] The hot melt adhesive layer, as the bonding layer between the GMT composite board layer and the fabric layer, can firmly bond the two together to form an integral structure, improving the strength and stability of the car roof. The fabric layer has certain air permeability and hygroscopicity, can keep the air inside the vehicle circulating, reduce the sense of dampness and stuffiness, and at the same time helps prevent the growth of bacteria and mites.

[0010] In the GMT composite board layer, the composite fiber mat serves as the main reinforcing skeleton, providing the mechanical properties and dimensional stability of the board. The modified bamboo fiber has excellent moisture absorption, air permeability and antibacterial properties, can be embedded in the composite fiber mat structure, increasing the antibacterial and air permeability of the composite fiber mat. Tea tree oil has antibacterial, anti-inflammatory, insecticidal and acaricidal properties, improving the antibacterial biological activity of the overall system. Sodium tripolyphosphate regulates the pH value of the overall system, helps the dispersion and stability of other components, makes each component mix evenly, and improves the corrosion resistance of the board.

[0011] β-glycerophosphate disodium has good biocompatibility, making each component in the system mix evenly. Lecithin helps the dispersion of tea tree oil. Modified talc powder has good filling properties, reduces the density and cost of the board, while improving the hardness and wear resistance of the board and enhancing its compatibility with the GMT matrix. The expandable microsphere foaming agent expands during heating to form a closed-cell structure, thus improving the heat insulation performance of the board and reducing the weight. Each component is evenly mixed, and the obtained GMT composite board layer has good mechanical properties, wear resistance and antibacterial properties.

[0012] Preferably, the preparation method of the modified bamboo fiber includes the following steps:

[0013] (1) Disperse bamboo fiber in NaOH solution, stir for 1 - 2 h, wash with water, then disperse in an aqueous solution of silane coupling agent, add calcium carbonate, ultrasonicate for 30 - 35 min, and dry to obtain pretreated bamboo fiber;

[0014] (2) Disperse the modified loofah fiber in deionized water, add the pretreated bamboo fiber from step (1), stir at a temperature of 60 - 65 °C for 2 - 3 h, add glacial acetic acid, chitosan, and sorbitol, continue to stir for 2 - 3 h, dry, and pulverize to obtain the modified bamboo fiber.

[0015] By adopting the above technical solution, the NaOH solution softens the bamboo fiber and removes the sizing impurities in the bamboo fiber, increasing the specific surface area of the bamboo fiber. The washed bamboo fiber is dispersed in an aqueous solution of a silane coupling agent, and the silane coupling agent can improve the compatibility of the bamboo fiber with other materials and enhance the bonding strength between the bamboo fiber and other materials. Calcium carbonate can be loaded on the surface and pores of the bamboo fiber, improving the rigidity and hardness of the bamboo fiber.

[0016] The modified loofah fiber is dispersed in deionized water. The loofah fiber has a natural porous structure, good mechanical strength and toughness. The modified loofah fiber can be fully combined with the bamboo fiber, and the modified loofah fiber and the bamboo fiber are mutually loaded, improving the mechanical properties, porosity and specific surface area of the bamboo fiber. Chitosan dispersed in deionized water has a certain viscosity and film-forming property, making the modified loofah fiber and the bamboo fiber adhere tightly, increasing the structural stability of the modified bamboo fiber, and improving the flexibility, water resistance and biocompatibility of the modified bamboo fiber. Sorbitol has good dispersibility, making each component in the system disperse evenly, increasing the structural stability of the modified bamboo fiber. Subsequently, the modified bamboo fiber is applied to GMT composite material boards, increasing the comprehensive properties such as the mechanical properties, wear resistance and bactericidal property of the GMT composite material boards.

[0017] Preferably, the mass ratio of the bamboo fiber, the modified loofah fiber and chitosan is 1:0.5 - 0.6:0.1 - 0.2.

[0018] By adopting the above technical solution, further limiting the mass ratio of the bamboo fiber, the modified loofah fiber and chitosan within a certain range can improve the comprehensive properties of the bamboo fiber. The bamboo fiber has high strength and good toughness. The modified loofah fiber and the bamboo fiber can adsorb and combine with each other, increasing the mechanical properties and adsorption property of the bamboo fiber. Chitosan has a certain viscosity and film-forming property, making the bamboo fiber and the modified loofah fiber adhere tightly, increasing the flexibility of the modified bamboo fiber. Subsequently, when applied to GMT composite material boards, it increases the mechanical strength, weather resistance and antibacterial property of the GMT composite material boards, thereby extending the service life of the boards.

[0019] Preferably, the preparation method of the modified loofah fiber comprises the following steps: pulverize the loofah fiber, disperse it in a sodium hydroxide solution, stir for 10-12 min, wash with water, then disperse it in hydrogen peroxide, stir for 25-30 min, wash with water, then disperse it in deionized water, add 3-chloro-2-hydroxypropyltrimethylammonium chloride, nano-carbon powder, and hydroxypropyl methylcellulose, and stir at a temperature of 70-75 °C for 3-4 h, dry, and filter to obtain the treated loofah fiber, and then spray an adhesive mixture on the surface of the treated loofah fiber to obtain the modified loofah fiber;

[0020] The adhesive mixture is made by mixing deionized water, ethylene glycol, dextrin gum, lignosulfonate, and disodium ethylenediaminetetraacetate.

[0021] By adopting the above technical solution, the pulverized loofah fiber is dispersed in a sodium hydroxide solution to remove impurities such as lignin and hemicellulose in the loofah fiber, and at the same time, the roughness of the fiber surface is increased; then it is dispersed in hydrogen peroxide to further remove impurities in the loofah fiber and improve its surface properties.

[0022] The treated loofah fiber is dispersed in deionized water again, and 3-chloro-2-hydroxypropyltrimethylammonium chloride, nano-carbon powder, and hydroxypropyl methylcellulose are added. 3-chloro-2-hydroxypropyltrimethylammonium chloride is used as a dispersant, and through the interaction of its cationic part with the negative charges on the surfaces of the loofah fiber and the nano-carbon powder, the aggregation between particles is reduced, and the dispersibility of these particles in water is enhanced. The nano-carbon powder has good mechanical properties, thermal stability, and electrical conductivity, can be loaded on the surface and pores of the loofah fiber, effectively fills the voids between the fibers, forms a more compact structure, and increases the strength, wear resistance, and toughness of the loofah fiber. The thickening and adhesive properties of hydroxypropyl methylcellulose help the nano-carbon powder to adhere to the surface of the loofah fiber, improve the comprehensive performance of the modified loofah fiber, and subsequent application to the modified bamboo fiber can improve the mechanical properties, wear resistance, flexibility, and antibacterial properties of the modified bamboo fiber.

[0023] Spray the adhesive mixture on the surface of the treated loofah fiber. Dextrin gum has high viscosity, and lignosulfonate has excellent adhesion and dispersibility. Combined with dextrin gum, the adhesion of the adhesive composition is improved, which helps the uniform distribution of the adhesive on the substrate. Disodium ethylenediaminetetraacetate improves the stability of the adhesive composition. The various components are mixed to improve the viscosity and dispersibility of the adhesive composition. The adhesive composition coats the treated loofah fiber, not only makes the loofah fiber and the nano-carbon powder adhere tightly, but also increases the adhesiveness of the modified loofah fiber. Subsequent application to bamboo fiber can improve the adhesion between bamboo fiber and other components, which helps to improve the performance of GMT composite material sheets.

[0024] Preferably, the preparation method of the modified talcum powder comprises the following steps:

[0025] (1) Disperse the talcum powder in a dilute nitric acid solution, stir at room temperature for 1 - 2 h, wash with water, then disperse in ethanol, add palmitic acid, titanate coupling agent and sodium p-methoxy fatty amide benzene sulfonate, stir at 60 - 65 °C for 2 - 3 h, filter, and dry to obtain pretreated talcum powder;

[0026] (2) Disperse the modified nanocellulose in deionized water, add the pretreated talcum powder obtained in step (1), stir at 70 - 75 °C for 1 - 2 h, then add asbestos fiber and polyvinyl alcohol, stir for 3 - 5 h, and dry to obtain the modified talcum powder.

[0027] By adopting the above technical solution, dilute nitric acid is used to remove impurities on the surface of the talcum powder or perform slight surface etching to increase its surface area and reaction activity; then it is dispersed in ethanol, and palmitic acid, titanate coupling agent and sodium p-methoxy fatty amide benzene sulfonate are added. Palmitic acid has good lubricity and dispersibility, which helps the talcum powder and other additives to be better dispersed in ethanol, while reducing the friction between particles. The titanate coupling agent can react with functional groups such as hydroxyl groups on the surface of the talcum powder to form chemical bonding, improving the compatibility and interfacial bonding force between the talcum powder and the polymer matrix, thereby enhancing the mechanical properties and heat resistance of the composite material. The titanate coupling agent can also improve the dispersibility of the talcum powder in the polymer and reduce the agglomeration phenomenon. Sodium p-methoxy fatty amide benzene sulfonate has good water solubility and dispersibility, reducing the surface tension of the mixture, improving the wettability and fluidity, and making the talcum powder better dispersed uniformly.

[0028] Disperse the modified nanocellulose in deionized water to form a nanocellulose dispersion liquid, add the pretreated talcum powder, and the talcum powder and nanocellulose are fully mixed. The nanocellulose coats the talcum powder particles to a certain extent. The asbestos fiber has high tensile strength, high flexibility, and resistance to chemical and thermal erosion. The talcum powder can be loaded on the surface of the asbestos fiber, and the modified nanocellulose can coat the asbestos fiber, increasing the adhesion between the talcum powder and the asbestos fiber, making the modified talcum powder have better mechanical properties, heat resistance and chemical stability. Polyvinyl alcohol has good water solubility, film-forming property, adhesiveness and emulsifying property. Cooperating with the modified nanocellulose, the mixed system forms a denser network structure, improving the overall performance. The modified talcum powder obtained by mixing each component has better comprehensive performance and is applied to the GMT composite material board to increase the mechanical properties, wear resistance and stability of the GMT composite material board.

[0029] Preferably, the mass ratio of the talcum powder, modified nanocellulose and asbestos fiber is 1:0.7 - 0.8:0.2 - 0.3.

[0030] By adopting the above technical solution, further limiting the mass ratio of talcum powder, modified nano-cellulose and asbestos fiber within a certain range, the obtained modified talcum powder has better mechanical properties. Talcum powder has high hardness, high strength and good dispersibility. Modified nano-cellulose has high crystallinity and excellent mechanical properties, and can form a tight network structure to enhance the strength and toughness of the material. Asbestos fiber has high tensile strength, tensile strength and flexural strength. Talcum powder can be loaded on the surface of asbestos fiber, and modified nano-cellulose can coat talcum powder and asbestos fiber, making the adhesion between talcum powder and asbestos fiber tight, increasing the mechanical strength, heat resistance and overall stability of the modified talcum powder. Subsequently, it is applied to the GMT composite automotive sheet to improve the mechanical properties, heat resistance, sound insulation and heat insulation effect and overall quality of the system.

[0031] Preferably, the preparation method of the modified nano-cellulose includes the following steps: dispersing oxidized nano-cellulose in deionized water, adding N,N-dimethylformamide, stirring at 85 - 90 °C for 3 - 4 h, filtering and drying to obtain treated oxidized nano-cellulose; redispersing the treated oxidized nano-cellulose in an aqueous solution of sodium periodate, reacting at 60 - 70 °C for 45 - 50 min, cooling to room temperature, washing to neutrality and drying to obtain nano-cellulose containing aldehyde groups; dispersing the nano-cellulose containing aldehyde groups in deionized water, adding seaweed fiber, titanium dioxide and sodium dodecyl sulfate, stirring at 70 - 80 °C for 2 - 3 h and drying to obtain modified nano-cellulose.

[0032] By adopting the above technical solution, dispersing oxidized nano-cellulose in deionized water, N,N-dimethylformamide improves the dispersibility of nano-cellulose and reduces the probability of agglomeration of oxidized nano-cellulose. Redispersing the treated oxidized nano-cellulose in an aqueous solution of sodium periodate introduces aldehyde groups onto the nano-cellulose to obtain nano-cellulose containing aldehyde groups.

[0033] Dispersing the nano-cellulose containing aldehyde groups in deionized water, adding seaweed fiber, titanium dioxide and sodium dodecyl sulfate. Seaweed fiber has good biocompatibility, toughness and tensile strength. Nano-cellulose can coat seaweed fiber to increase the mechanical properties of the system. Titanium dioxide has excellent antibacterial and anti-ultraviolet properties, and titanium dioxide can be loaded on the surface of seaweed fiber. Nano-cellulose makes the adhesion between titanium dioxide and seaweed fiber tight. Sodium dodecyl sulfate improves the dispersibility of nano-cellulose, seaweed fiber and titanium dioxide in deionized water, making each mixture evenly dispersed. The obtained modified nano-cellulose has good strength, toughness, good biocompatibility, antibacterial properties and anti-ultraviolet properties, and subsequently improves the corresponding properties of talcum powder.

[0034] Preferably, the hot melt adhesive layer is polyurethane hot melt adhesive, and the fabric layer is spunbond non-woven fabric or knitted sponge fabric.

[0035] By adopting the above technical solutions, the polyurethane hot melt adhesive has excellent bonding performance, which can ensure the firm combination between the various layers of materials of the automobile ceiling. The spunbond non-woven fabric is soft, light, and easy to be processed into various shapes and sizes. It has good wear resistance, sound insulation and heat insulation, and can provide good covering effect and decoration.

[0036] Preferably, the composite fiber felt is composed of PP fibers and glass fibers.

[0037] By adopting the above technical solutions, in the composite fiber felt, the PP fibers are the bonding matrix and the glass fibers are the reinforcing materials. The obtained composite fiber felt has good wear resistance, weather resistance, high strength, corrosion resistance and heat resistance.

[0038] In a second aspect, the present application also provides a preparation method for an automobile ceiling made of GMT composite material, including the following steps:

[0039] 1) Disperse the expandable microsphere foaming agent and EVA in deionized water and disperse evenly to obtain a dispersion liquid;

[0040] 2) Add the modified bamboo fibers, tea tree oil, sodium tripolyphosphate, β-glycerophosphate disodium, lecithin, and modified talc powder to the dispersion liquid and perform ultrasonic oscillation for 1 - 2 h to obtain an extraction liquid;

[0041] 3) Immerse the composite felt in the extraction liquid and repeatedly turn it over for impregnation for 30 - 35 min. After impregnation, place it in an oven at a temperature of 75 - 80 °C and dry for 6 - 8 h to obtain an intermediate;

[0042] 4) Heat and foam the intermediate at a temperature of 195 - 200 °C for 40 - 45 min, and then perform hot pressing at a temperature of 195 - 200 °C to obtain a GMT composite board layer;

[0043] 5) Bond a hot melt adhesive layer on one side of the GMT composite board layer, lay the fabric flat on the side of the GMT composite board layer with the hot melt adhesive layer attached, and then perform hot pressing, cutting and assembling to obtain an automobile ceiling made of GMT composite material.

[0044] By adopting the above technical solutions and the above preparation method, the operation is simple, the process time is short, which helps to improve the production efficiency of preparing the automobile ceiling made of GMT composite material. The obtained automobile ceiling made of GMT composite material has good mechanical properties, wear resistance and sealing performance.

[0045] In summary, the present application has the following beneficial effects:

[0046] 1. In this application, the GMT material is a composite material with a thermoplastic resin as the matrix and a glass fiber mat as the reinforcing framework. It has the advantages of light weight, toughness, rigidity, impact resistance, and corrosion resistance. The GMT composite board layer plays a supporting and protecting role in the car roof, can withstand a certain amount of external force impact, and improves the riding comfort of the car.

[0047] 2. In the GMT composite board layer of this application, the composite fiber mat serves as the main reinforcing framework, providing the mechanical properties and dimensional stability of the board. The modified bamboo fiber has excellent moisture absorption, breathability, and antibacterial properties, and can be embedded in the composite fiber mat structure to increase the antibacterial and breathable properties of the composite fiber mat.

[0048] 3. After forming, the thickness of the GMT composite material car roof in this application is ≤5.5 mm. Due to its high specific strength, the GMT composite material has a larger headroom compared to the PU roof. Compared with PU, it has lower residues and volatiles of harmful substances such as benzene, aldehyde, and phenol. The GMT composite material has almost no odor, can be processed and formed repeatedly, and the remaining scraps can also be recycled. It has a high degree of design freedom, can achieve a greater forming depth, can choose the "overall flanging" process, the process is simple, the production efficiency is high, the investment in molds and equipment is lower, and the unit processing cost is lower. Detailed implementation manners

[0049] The following further elaborates on this application in conjunction with examples.

[0050] The raw materials used in the examples and comparative examples can all be obtained commercially.

[0051] Preparation example of modified bamboo fiber

[0052] Preparation example 1-1

[0053] The preparation method of the modified bamboo fiber includes the following steps:

[0054] (1) Disperse 35 kg of bamboo fiber in 55 L of a NaOH solution with a mass fraction of 3%, stir for 2 h, wash with water, then disperse in an aqueous solution of a silane coupling agent KH-550 with a mass fraction of 0.3%, add 1.2 kg of calcium carbonate, ultrasonicate for 35 min, and dry to obtain pretreated bamboo fiber;

[0055] (2) Disperse the modified loofah fiber in 110 L of deionized water, add the pretreated bamboo fiber from step (1), stir at a temperature of 65 °C for 3 h, add 3 L of glacial acetic acid, chitosan, and 2 kg of sorbitol, continue to stir for 3 h, dry, and pulverize to obtain the modified bamboo fiber.

[0056] The mass ratio of bamboo fiber, modified loofah fiber, and chitosan is 1:0.5:0.2.

[0057] Preparation method of modified loofah fiber, comprising the following steps: pulverize 25 kg of loofah fiber, disperse it in 50 L of sodium hydroxide solution with a mass fraction of 4%, stir for 12 min, wash with water, then disperse it in 40 L of hydrogen peroxide, stir for 30 min, wash with water, then disperse it in 60 L of deionized water, add 3 kg of 3-chloro-2-hydroxypropyltrimethylammonium chloride, 6 kg of nano-carbon powder, and 3 kg of hydroxypropyl methylcellulose, stir at a temperature of 75 °C for 4 h, dry, filter to obtain the treated loofah fiber, and then spray an adhesive mixture on the surface of the treated loofah fiber to obtain the modified loofah fiber;

[0058] The adhesive mixture is made by mixing 100 L of deionized water, 8 L of ethylene glycol, 20 kg of dextrin glue, 4 kg of lignosulfonate, and 2 kg of disodium ethylenediaminetetraacetate.

[0059] Preparation Examples 1-2

[0060] The difference from Preparation Example 1-1 is that in step (2), no modified loofah fiber is added.

[0061] Preparation Example 1-3

[0062] The difference from Preparation Example 1-1 is that in step (2), no chitosan is added.

[0063] Preparation Example 1-4

[0064] The difference from Preparation Example 1-1 is that the mass ratio of bamboo fiber, modified loofah fiber, and chitosan is 1:0.6:0.1.

[0065] Preparation Example 1-5

[0066] The difference from Preparation Example 1-1 is that the mass ratio of bamboo fiber, modified loofah fiber, and chitosan is 1:0.1:0.5.

[0067] Preparation Example 1-6

[0068] The difference from Preparation Example 1-1 is that in the preparation method of the modified loofah fiber, no nano-carbon powder is added.

[0069] Preparation Example 1-7

[0070] The difference from Preparation Example 1-1 is that in the preparation method of the modified loofah fiber, no dextrin glue is added.

[0071] Preparation Examples of Modified Talc Powder

[0072] Preparation Example 2-1

[0073] Preparation method of modified talc powder, comprising the following steps:

[0074] (1) Disperse 30 kg of talcum powder in 45 L of a 10% by mass dilute nitric acid solution, stir at room temperature for 2 h, wash with water, then disperse in 55 L of ethanol. Add 2 kg of palmitic acid, 3 kg of titanate coupling agent, and 1 kg of sodium p-methoxy fatty acid amide benzene sulfonate, stir at 65 °C for 3 h, filter, and dry to obtain pretreated talcum powder;

[0075] (2) Disperse the modified nano-cellulose in 110 L of deionized water, add the pretreated talcum powder from step (1), stir at 75 °C for 2 h, then add asbestos fiber and 1 kg of polyvinyl alcohol, stir for 5 h, and dry to obtain modified talcum powder.

[0076] The titanate coupling agent is isopropyl tris(dioctylpyrophosphate acyl) titanate coupling agent.

[0077] The mass ratio of talcum powder, modified nano-cellulose, and asbestos fiber is 1:0.7:0.3.

[0078] The preparation method of the modified nano-cellulose includes the following steps: Disperse 30 kg of oxidized nano-cellulose in 50 L of deionized water, add 5 L of N-N-dimethylformamide, stir at 90 °C for 4 h, filter, and dry to obtain the treated oxidized nano-cellulose; Disperse the treated oxidized nano-cellulose in 100 L of 1 M sodium periodate aqueous solution, react at 70 °C for 50 min, cool to room temperature, wash until neutral, and dry to obtain nano-cellulose containing aldehyde groups; Disperse the nano-cellulose containing aldehyde groups in 100 L of deionized water, add 8 kg of seaweed fiber, 6 kg of titanium dioxide, and 2 kg of sodium dodecyl sulfate, stir at 80 °C for 3 h, and dry to obtain modified nano-cellulose.

[0079] Preparation Example 2-2

[0080] The difference from Preparation Example 2-1 is that in step (2), no modified nano-cellulose is added.

[0081] Preparation Example 2-3

[0082] The difference from Preparation Example 2-1 is that in step (2), no asbestos fiber is added.

[0083] Preparation Example 2-4

[0084] The difference from Preparation Example 2-1 is that the mass ratio of talcum powder, modified nano-cellulose, and asbestos fiber is 1:0.8:0.2.

[0085] Preparation Example 2-5

[0086] The difference from Preparation Example 2-1 is that the mass ratio of talcum powder, modified nano-cellulose, and asbestos fiber is 1:0.1:0.6.

[0087] Preparation Example 2-6

[0088] The difference from Preparation Example 2-1 is that in the preparation method of the modified nanocellulose, seaweed fiber is not added.

[0089] Preparation Example 2-7

[0090] The difference from Preparation Example 2-1 is that in the preparation method of the modified nanocellulose, nano-titanium dioxide is not added. Examples

[0091] Example 1

[0092] A GMT composite material automotive ceiling, comprising a GMT composite board layer, a hot melt adhesive layer and a fabric layer. The GMT composite board layer, by weight, comprises the following raw materials: 100 kg of composite fiber felt, 22 kg of modified bamboo fiber, 3 kg of tea tree oil, 1 kg of sodium tripolyphosphate, 2 kg of β-glycerophosphate disodium, 0.8 kg of lecithin, 15 kg of modified talc powder, 6 kg of expandable microsphere foaming agent, and 200 kg of deionized water;

[0093] The hot melt adhesive layer is polyurethane hot melt adhesive with a thickness of 0.03 mm, and the fabric layer is spunbond non-woven fabric with a thickness of 1.2 mm; the composite fiber felt is composed of 30 kg of PP fiber and 60 kg of glass fiber. After mixing the PP fiber and the glass fiber, carding is carried out to make them arranged neatly, and then molding and curing are carried out at a curing temperature of 130 °C to obtain a composite fiber felt with a thickness of 2 mm.

[0094] The preparation method of the above GMT composite material automotive ceiling comprises the following steps:

[0095] 1) Disperse the expandable microsphere foaming agent and 1 kg of EVA (ethylene-vinyl acetate copolymer) in deionized water, and disperse evenly to obtain a dispersion;

[0096] 2) Add the modified bamboo fiber, tea tree oil, sodium tripolyphosphate, β-glycerophosphate disodium, lecithin, and modified talc powder to the dispersion, and perform ultrasonic oscillation for 2 h to obtain an extraction solution;

[0097] 3) Immerse the composite felt in the extraction solution and repeatedly turn it over and immerse it for 35 min, and then dry it at a temperature of 80 °C for 8 h to obtain an intermediate;

[0098] 4) Heat and foam the intermediate at a temperature of 200 °C for 45 min, and then hot press and mold it at a temperature of 200 °C to obtain the GMT composite board layer; the expandable microsphere foaming agent is purchased from Guangdong Yongfeng Chemical Co., Ltd.

[0099] 5) Bond a hot-melt adhesive layer on one side of the GMT composite board layer at a heating temperature of 130 °C. Lay the fabric flat on the side of the GMT composite board layer with the hot-melt adhesive layer, and then perform hot pressing to form. The hot pressing temperature is 180 °C. Cut and assemble to obtain a GMT composite automotive ceiling;

[0100] Among them, in the cutting process, use high-pressure water or a mold to cut the GMT ceiling to ensure that the cutting edge is flat and meets the design requirements to obtain the required semi-finished ceiling. Collect the cut-off scraps, classify and process them. Some scraps may be recyclable, while others may need to be disposed of in accordance with relevant regulations.

[0101] Then assemble the accessories. Prepare the required accessories such as lamp fixing frames, wire harness clips, and hooks. Use positioning pins to accurately position the accessories on the GMT substrate, and use pasting or riveting methods to firmly install the accessories on the GMT substrate. For the edge wrapping position, adopt the overall flanging method to obtain a GMT composite automotive ceiling.

[0102] The modified bamboo fiber is prepared by Preparation Example 1-1; the modified talcum powder is prepared by Preparation Example 2-1.

[0103] Example 2

[0104] A GMT composite automotive ceiling, different from Example 1 in that the GMT composite board layer, by weight, comprises the following raw materials: 90 kg of composite fiber felt, 30 kg of modified bamboo fiber, 5 kg of tea tree oil, 2 kg of sodium tripolyphosphate, 4 kg of β-glycerophosphate disodium, 0.5 kg of lecithin, 20 kg of modified talcum powder, 4 kg of expandable microsphere foaming agent, and 190 kg of deionized water;

[0105] Among them, the fabric layer is knitted sponge cloth with a thickness of 3.2 mm.

[0106] Example 3

[0107] A GMT composite automotive ceiling, different from Example 1 in that the modified bamboo fiber is prepared by Preparation Example 1-2.

[0108] Example 4

[0109] A GMT composite automotive ceiling, different from Example 1 in that the modified bamboo fiber is prepared by Preparation Example 1-3.

[0110] Example 5

[0111] A GMT composite automotive ceiling, different from Example 1 in that the modified bamboo fiber is prepared by Preparation Example 1-4.

[0112] Example 6

[0113] A GMT composite material automotive ceiling, different from Example 1 in that the modified bamboo fiber is prepared by Preparation Examples 1-5.

[0114] Example 7

[0115] A GMT composite material automotive ceiling, different from Example 1 in that the modified bamboo fiber is prepared by Preparation Examples 1-6.

[0116] Example 8

[0117] A GMT composite material automotive ceiling, different from Example 1 in that the modified bamboo fiber is prepared by Preparation Examples 1-7.

[0118] Example 9

[0119] A GMT composite material automotive ceiling, different from Example 1 in that the modified talc powder is prepared by Preparation Example 2-2.

[0120] Example 10

[0121] A GMT composite material automotive ceiling, different from Example 1 in that the modified talc powder is prepared by Preparation Example 2-3.

[0122] Example 11

[0123] A GMT composite material automotive ceiling, different from Example 1 in that the modified talc powder is prepared by Preparation Example 2-4.

[0124] Example 12

[0125] A GMT composite material automotive ceiling, different from Example 1 in that the modified talc powder is prepared by Preparation Example 2-5.

[0126] Example 13

[0127] A GMT composite material automotive ceiling, different from Example 1 in that the modified talc powder is prepared by Preparation Example 2-6.

[0128] Example 14

[0129] A GMT composite material automotive ceiling, different from Example 1 in that the modified talc powder is prepared by Preparation Example 2-7. Comparative Example

[0130] Comparative Example 1

[0131] A GMT composite material automotive ceiling, different from Example 1 in that no modified bamboo fiber is added.

[0132] Comparative Example 2

[0133] A GMT composite material automotive ceiling, which is different from Example 1 in that the modified bamboo fiber is replaced with an equal amount of bamboo fiber.

[0134] Comparative Example 3

[0135] A GMT composite material automotive ceiling, which is different from Example 1 in that no modified talcum powder is added.

[0136] Comparative Example 4

[0137] A GMT composite material automotive ceiling, which is different from Example 1 in that the modified talcum powder is replaced with an equal amount of talcum powder.

[0138] Performance detection test

[0139] Perform performance tests on the GMT composite material automotive ceilings prepared in Examples 1 - 14 and Comparative Examples 1 - 4;

[0140] The tensile strength and elongation at break are tested in accordance with GB / T 1499 - 2005, the flexural strength is tested in accordance with GB / T 9341 - 2008, and the Shore hardness (D type) is tested in accordance with the ISO 7619 - 97 standard.

[0141] Using a stamping testing machine, clamp the substrate between two steel plates with holes in the middle of the testing machine, keep the punch perpendicular to the plane of the substrate, and test the impact strength of the sample. The test results are shown in Table 1.

[0142] Table 1 Test data of examples and comparative examples

[0143]

[0144] As can be seen from Table 1, the GMT composite material automotive ceilings prepared in Examples 1 - 2 of the present application have good hardness, mechanical properties and durability. Among them, the hardness of Example 1 is 78, the tensile strength in the original state is 29.8 MPa, the tensile strength after aging at 120 °C for 500 h is 27.7 MPa, the elongation at break is 10.6%, the impact strength is 20.6 MPa, and the flexural strength is 18.9 MPa. It shows that the prepared GMT composite material automotive ceiling has excellent mechanical properties, aging resistance and temperature resistance, and each component is uniformly mixed, and the obtained GMT composite board layer has good mechanical properties, making the automotive ceiling have excellent aging resistance.

[0145] In the preparation methods of modified bamboo fibers in Examples 3-4, modified loofah fibers and chitosan were not added respectively. In Examples 5-6, the mass ratios of bamboo fibers, modified loofah fibers and chitosan were changed. As can be seen from Table 1, the performance test results of hardness, tensile strength in the original state, tensile strength after aging at 120°C for 500 h, elongation at break, impact strength and flexural strength in Examples 3-4 were all worse than those in Examples 1-2 and Example 5. The above performance effects in Example 6 were all better than those in Examples 3-4, but worse than those in Examples 1-2 and Example 5, indicating that modified loofah fibers and bamboo fibers can adsorb and combine with each other, increasing the mechanical properties and adsorption properties of bamboo fibers. Chitosan makes the bamboo fibers and modified loofah fibers bond tightly, increasing the flexibility of the modified bamboo fibers. Subsequently, when applied to GMT composite material plates, it increases the mechanical strength, weather resistance and antibacterial properties of GMT composite material plates, thereby extending the service life of the plates.

[0146] In the preparation methods of modified loofah fibers in Examples 7-8, nano-carbon powder and dextrin glue were not added respectively. As can be seen from Table 1, the performance test results of hardness, tensile strength in the original state, tensile strength after aging at 120°C for 500 h, elongation at break, impact strength and flexural strength in Examples 7-8 were all better than those in Example 3, but worse than those in Examples 1-2, indicating that nano-carbon powder has good mechanical properties, thermal stability and electrical conductivity, can be loaded on the surface and pores of loofah fibers, effectively fill the voids between fibers, form a more compact structure, and increase the strength, wear resistance and toughness of loofah fibers; spraying an adhesive mixture on the surface of the treated loofah fibers, dextrin glue has high viscosity, making the loofah fibers and nano-carbon powder bond tightly. Subsequently, when applied to bamboo fibers, it improves the adhesion between bamboo fibers and other components, contributing to the improvement of the performance of GMT composite material plates.

[0147] In the preparation methods of modified talc powder in Examples 9-10, modified nano-cellulose and asbestos fibers were not added respectively. In Examples 11-12, the mass ratios of talc powder, modified nano-cellulose and asbestos fibers were changed. As can be seen from Table 1, the performance test results of hardness, tensile strength in the original state, tensile strength after aging at 120°C for 500 h, elongation at break, impact strength and flexural strength in Examples 9-10 were all worse than those in Examples 1-2 and Example 11. The above performance effects in Example 12 were all better than those in Examples 9-10, but worse than those in Examples 1-2 and Example 11, indicating that asbestos fibers have high tensile strength, tensile strength and flexural strength, talc powder can be loaded on the surface of asbestos fibers, and modified nano-cellulose can coat talc powder and asbestos fibers, making the bond between talc powder and asbestos fibers tight, increasing the mechanical strength, heat resistance and overall stability of modified talc powder; subsequently, when applied to GMT composite material automotive plates, it improves the mechanical properties, heat resistance, sound insulation and heat insulation effects and overall quality of the system.

[0148] In the preparation methods of the modified nanocellulose in Examples 13 - 14, seaweed fibers and nano - titanium dioxide are not added respectively. As can be seen from Table 1, the performance test results of the hardness, tensile strength in the original state, tensile strength after aging at 120°C for 500 h, elongation at break, impact strength, and flexural strength of Examples 13 - 14 are all better than those of Example 9, but worse than those of Examples 1 - 2. This indicates that seaweed fibers have good biocompatibility, toughness, and tensile strength, nanocellulose can coat seaweed fibers, increasing the mechanical properties of the system, titanium dioxide has excellent antibacterial and anti - ultraviolet properties, titanium dioxide can be loaded on the surface of seaweed fibers, and nanocellulose makes the adhesion between titanium dioxide and seaweed fibers tight.

[0149] In Comparative Example 1 and Comparative Example 3, modified bamboo fibers and modified talcum powder are not added respectively. As can be seen from Table 1, compared with Example 1, the performance test results of the hardness, tensile strength in the original state, tensile strength after aging at 120°C for 500 h, elongation at break, impact strength, and flexural strength of Comparative Example 1 and Comparative Example 3 are significantly worse than those of Examples 1 - 2. This indicates that modified bamboo fibers have excellent moisture absorption, air permeability, and antibacterial properties, can be embedded in the composite fiber felt structure, increasing the antibacterial and air permeability of the composite fiber felt; modified talcum powder has good filling properties, reducing the density and cost of the board, while improving the hardness and wear resistance of the board, and improving its compatibility with the GMT matrix.

[0150] In Comparative Example 2 and Comparative Example 4, the modified bamboo fibers are replaced with the same amount of bamboo fibers and the modified talcum powder is replaced with the same amount of talcum powder respectively. As can be seen from Table 1, the performance test results of the hardness, tensile strength in the original state, tensile strength after aging at 120°C for 500 h, elongation at break, impact strength, and flexural strength of Comparative Example 2 and Comparative Example 4 are significantly worse than those of Examples 1 - 2, but better than those of Comparative Example 1 and Comparative Example 3. This indicates that the modified bamboo fibers and modified talcum powder of this application have good mechanical properties, mechanical performance, and aging resistance, maintaining the structural strength and performance stability of the automotive ceiling.

[0151] This specific embodiment is only an explanation of this application, and it is not a limitation of this application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions according to needs, but as long as it is within the scope of the claims of this application, it is protected by the patent law.

Claims

1. A GMT composite material automobile roof, comprising a GMT composite sheet layer, a hot melt adhesive layer and a fabric layer, characterized in that: The GMT composite sheet layer comprises the following raw materials, by weight: 90-100 parts of composite fiber felt, 22-30 parts of modified bamboo fiber, 3-5 parts of tea tree oil, 1-2 parts of sodium tripolyphosphate, 2-4 parts of β-glycerophosphate disodium, 0.5-0.8 parts of lecithin, 15-20 parts of modified talc, 4-6 parts of expandable microsphere foaming agent, and 190-200 parts of deionized water; The preparation method of the modified bamboo fiber comprises the following steps: (1) dispersing the bamboo fiber in a NaOH solution, stirring for 1-2 hours, washing with water, and then dispersing the bamboo fiber in a silane coupling agent aqueous solution, adding calcium carbonate, ultrasonicating for 30-35 minutes, and drying to obtain pretreated bamboo fiber; (2) dispersing the modified loofah fiber in deionized water, adding the pretreated bamboo fiber of step (1), stirring at a temperature of 60-65° C. for 2-3 h, adding glacial acetic acid, chitosan, and sorbitol, continuing to stir for 2-3 h, drying, and crushing to obtain modified bamboo fiber; The preparation method of the modified talcum powder comprises the following steps: (1) dispersing talc in a dilute nitric acid solution, stirring at room temperature for 1-2 hours, washing with water, and then dispersing in ethanol, adding palmitic acid, titanate coupling agent and sodium p-methoxy fatty amide benzene sulfonate, stirring at 60-65° C. for 2-3 hours, filtering, and drying to obtain pretreated talc; (2) dispersing the modified nanocellulose in deionized water, adding the pretreated talc powder of step (1), stirring at 70-75° C. for 1-2 h, then adding asbestos fiber and polyvinyl alcohol, stirring for 3-5 h, and drying to obtain modified talc powder; The loofah fiber is crushed, dispersed in a sodium hydroxide solution, stirred for 10-12 minutes, washed with water, dispersed in hydrogen peroxide, stirred for 25-30 minutes, washed with water, dispersed in deionized water, 3-chloro-2-hydroxypropyltrimethylammonium chloride, nano carbon powder, and hydroxypropyl methylcellulose are added, stirred at a temperature of 70-75° C. for 3-4 hours, dried, filtered, and treated loofah fiber is obtained, and then the adhesive mixture is sprayed on the surface of the treated loofah fiber to obtain modified loofah fiber; The adhesive mixture is prepared by mixing deionized water, ethylene glycol, dextrin glue, lignin sulfonate, and disodium ethylenediaminetetraacetate; The preparation method of the modified nanocellulose comprises the following steps: dispersing oxidized nanocellulose in deionized water, adding NN-dimethylformamide, stirring at a temperature of 85-90°C for 3-4 hours, filtering, and drying to obtain treated oxidized nanocellulose; re-dispersing the treated oxidized nanocellulose in a sodium periodate aqueous solution, reacting at a temperature of 60-70°C for 45-50 minutes, cooling to room temperature, washing to neutrality, and drying to obtain aldehyde-containing nanocellulose; dispersing the aldehyde-containing nanocellulose in deionized water, adding seaweed fiber, titanium dioxide, and sodium dodecyl sulfate, stirring at a temperature of 70-80°C for 2-3 hours, and drying to obtain modified nanocellulose.

2. The GMT composite material automobile roof according to claim 1, characterized in that: The mass ratio of the bamboo fiber, the modified loofah fiber and the chitosan is 1:0.5-0.6:0.1-0.

2.

3. The GMT composite material automobile roof according to claim 1, characterized in that: The mass ratio of the talcum powder, modified nanocellulose and asbestos fiber is 1:0.7-0.8:0.2-0.

3.

4. The GMT composite material automobile roof according to claim 1, characterized in that: The hot melt adhesive layer is polyurethane hot melt adhesive, and the fabric layer is spunbonded non-woven fabric.

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