Fiber reinforced thermoplastic composite material automotive interior ceiling and preparation method thereof

Abstract

The invention relates to the technical field of production of automobile roofs, and particularly discloses a fiber-reinforced thermoplastic composite automobile interior ceiling and a preparation method thereof. A fiber-reinforced thermoplastic composite material automotive interior ceiling comprises a base material and a fabric, and the base material sequentially comprises a bottom layer non-woven fabric, a first adhesive film, a blend fiber felt and a second adhesive film from bottom to top; the blend fiber felt is made of reinforced fibers and thermoplastic fibers through a non-woven process. The preparation method comprises the following steps of: preparing the base material by a dry method, forming the framework and compounding the fabric by using a set of mold to obtain a ceiling prototype, and then punching by using a cold mold and integrally curling and covering the base material and the fabric of the skylight opening to obtain the ceiling. The automobile interior ceiling made of the fiber-reinforced thermoplastic composite material has excellent dimensional stability and is more low-carbon and environment-friendly, and raw material leftover materials generated in the production process and products produced after the life cycle is ended are easy to recycle.

Description

Technical Field

[0001] The present application relates to the technical field of automobile ceiling production, and more specifically, to a fiber-reinforced thermoplastic composite automobile interior ceiling and a preparation method thereof. Background Art

[0002] The car roof is the part of the car interior located above the interior of the car passenger compartment. It is an important component in the car cab that combines decoration and functionality. Its main function is to improve the decorativeness of the cab. At the same time, the roof can also absorb noise inside the car, serve as a heat insulator from the outside of the car, and protect the occupants' heads, thereby improving the comfort and safety of the driver and passengers.

[0003] In addition, when the car is driving, the car roof needs to maintain good self-supporting performance and good matching effect with surrounding columns, skylights and other environmental parts to ensure reasonable overlap during assembly and good appearance after assembly. Therefore, the selection and preparation process of car roof materials are particularly important. As an important part of car interior, the car roof plays an indispensable role in improving the competitiveness of the car.

[0004] With regard to the above-mentioned related technologies, the inventors found that the vast majority of passenger car roofs on the market currently use a two-step wet method of PU structure, which requires two sets of hot molds for the molding of the frame and the lamination of the fabric respectively. The production process relies on liquid glue, which not only easily causes the production environment to be dirty and increases the difficulty of cleaning, but also increases the odor of the finished roof material. In addition, the composite materials with PU structure still have the problems of high technical difficulty and high cost in the treatment of scraps in the production process and recycling after the end of the product life cycle. Summary of the invention

[0005] In order to achieve low-carbon, environmentally friendly, low-VOC green production and ensure the self-supporting performance of the automobile roof, the present application provides a fiber-reinforced thermoplastic composite automobile interior ceiling and a preparation method thereof.

[0006] In a first aspect, the present application provides a fiber-reinforced thermoplastic composite automotive interior ceiling, which adopts the following technical solution: A fiber-reinforced thermoplastic composite automotive interior ceiling comprises a substrate and a fabric, wherein the substrate comprises, from bottom to top, a bottom non-woven fabric, a first adhesive film, a blended fiber felt and a second adhesive film; the blended fiber felt is made of reinforcing fibers and thermoplastic fibers in a mass ratio of 1:(0.85-1.15) through a non-woven process.

[0007] By adopting the above technical scheme and introducing blended fiber felt, the reinforcing fiber provides high strength and rigidity, while the thermoplastic fiber has good flexibility and processing performance. The two types of fibers are blended to prepare blended fiber felt, and the material has good processing and molding properties, which significantly enhances the overall strength, rigidity and deformation resistance of the automobile interior ceiling, ensuring that the automobile interior ceiling still maintains excellent self-supporting performance in high temperature and high humidity environment.

[0008] Optionally, the reinforcing fiber is glass fiber, which is formed by chopped alkali-free E glass untwisted stranded glass fiber yarn with a diameter of 10 μm and a linear density of 2400 tex.

[0009] Optionally, the thermoplastic fiber is any one or more combinations of polypropylene fiber, polyethylene fiber, polyester fiber and ES fiber.

[0010] Optionally, the first adhesive film and the second adhesive film are both maleic anhydride-modified polypropylene films.

[0011] Optionally, the bottom non-woven fabric is made of composite fibers with a core-skin structure, the core layer of the composite fibers is modified bamboo fibers, and the skin layer of the composite fibers is modified polypropylene fibers.

[0012] By adopting the above technical solution, bamboo fiber is a natural plant fiber with renewable and degradable properties. After forming a composite fiber with polypropylene fiber, the bottom non-woven fabric is prepared. It is easier to be recycled and processed after the life cycle of the car interior ceiling ends, which meets the requirements of environmental protection and sustainable development. In addition, bamboo fiber is light in weight, has natural antibacterial properties, and is more hygienic. It can further achieve the lightweight of the car interior ceiling and promote the realization of energy conservation and carbon reduction goals.

[0013] Both bamboo fiber and polypropylene fiber have excellent strength and toughness. The composite fiber with a skin-core structure prepared with modified bamboo fiber as the core layer and modified polypropylene fiber as the skin layer has higher strength and toughness, which can further improve the strength of the vehicle interior ceiling substrate and ensure the self-supporting performance of the prepared vehicle interior ceiling in different environments.

[0014] In addition, the related materials such as polypropylene and polyethylene used in the bottom non-woven fabric, the first adhesive film, the blended fiber felt and the second adhesive film are polyolefin polymers. The non-woven fabric is prepared by using modified polypropylene fiber as the cortex to wrap the bamboo fiber to form a composite fiber. It has better compatibility with the upper adhesive film and blended fiber felt, and can significantly promote the improvement of the interface bonding force, thereby ensuring the rigidity of the prepared automobile interior ceiling is enhanced.

[0015] Optionally, the method for preparing the bottom nonwoven fabric comprises the following steps: S1: dissolving hemicellulase in water and adjusting the pH of the solution to 4.5-5.5, adding bamboo fiber filaments, soaking at 35-50° C. for 0.5-1.5 h, taking out and drying to obtain modified bamboo fiber filaments; S2: mixing polypropylene particles and maleic anhydride in a mass ratio of 10:(1.5-2.5), adding dicumyl peroxide to blend, adding to a screw extruder for melt grafting reaction, and then melt spinning, stretching and heat setting to obtain modified polypropylene fiber filaments; S3: Distributing the modified polypropylene fiber filaments in parallel and uniformly on the surface of the modified bamboo fiber filaments, and then twisting and compounding them according to a twist of 300-500 twists / m and an S twist or a Z twist to obtain a composite fiber; S4: Cutting the composite fibers to form short fibers, opening, mixing, combing, web laying and needle punching the short fibers to obtain short fibers.

[0016] By adopting the above technical scheme, hemicellulase-treated bamboo fiber and maleic anhydride-grafted polypropylene fiber modification can effectively improve the compatibility between the sheath-core fibers, and obtain composite fibers with a sheath-core structure through twisting and composite treatment, which significantly improves the structural stability and mechanical properties of the underlying non-woven fabric, provides a reliable underlying fabric for the automobile interior ceiling, and further ensures the self-supporting performance of the automobile interior ceiling under different environmental conditions.

[0017] In a second aspect, the present application provides a method for preparing a fiber-reinforced thermoplastic composite automotive interior ceiling, using the following technical solution: A method for preparing a fiber-reinforced thermoplastic composite automotive interior ceiling comprises the following steps: S1: opening, mixing, combing, laying and needle punching glass fiber and thermoplastic fiber to obtain a blended fiber felt; laying a bottom non-woven fabric, a first adhesive film, a blended fiber felt and a second adhesive film in sequence, and obtaining a substrate after preheating, heating, plate making and cooling; S2: The substrate is heated to a surface temperature of 190±20°C, the robot puts the skylight reinforcement frame into the corresponding pit of the lower mold, the fabric is automatically transferred to the middle position of the upper and lower molds, the substrate is automatically transferred to the middle position of the upper and lower molds and is located below the fabric, the upper mold automatically falls, and the pressure is maintained to form, and the initial shape of the ceiling is obtained; S3: placing the preliminary form of the ceiling into a punching die, and positioning it according to the shape of the skylight window. The holding pressure of the punching press is 200±10 bar, and the holding time is 5±2s. The punching die is provided with a floating press plate and a cold die and a cold knife. The cold die and the cold knife punch out the redundant side holes to obtain the basic form of the ceiling. S4: The skylight base material and fabric of the ceiling base are rolled and covered as a whole.

[0018] By adopting the above technical solution and a dry manufacturing process, only one set of molds is used to complete the skeleton forming and fabric compounding. The prepared substrate has good free expansion performance after heating and has excellent rigidity. It can maintain good stability under high temperature and high humidity conditions and can meet the production needs of ceilings with a thickness of 4-6mm.

[0019] The traditional dry ceiling industry uses robotic water jet cutting for trimming and punching, and each cutting time takes 35-55 seconds. The size tolerance of the ceiling hole after cutting is ±1mm. The method of the present application uses a punching die for cutting, and each cutting time is only 3-7 seconds. The size tolerance of the ceiling hole after cutting can be controlled within ±0.5mm, which significantly improves the manufacturing efficiency of automotive interior ceilings, while also ensuring the stability of the assembly size of the entire vehicle.

[0020] The preparation process of the present application does not involve the use of liquid glue, which significantly reduces the odor and weight of the automotive interior ceiling substrate, and the process environment is cleaner and more hygienic, and is a green production process with sustainable development.

[0021] Optionally, the surface density of the substrate obtained in step S1 is 800-1000 g / m 2 , thickness is 4±0.5mm.

[0022] Optionally, the mass of the blended fiber felt is 40±5% of the mass of the substrate.

[0023] Optionally, in step S2, the conditions for pressure-holding molding are: the temperature of the upper and lower molds is 15±5°C, the molding pressure is 50±10 bar, and the pressure-holding time is 30±3s.

[0024] In summary, this application has the following beneficial effects: 1. Since the present application adopts reinforcing fiber and thermoplastic fiber to prepare the blended fiber felt in the ceiling substrate, it combines the high strength and high modulus of alkali-free E glass fiber and the high flexibility and easy processing performance of thermoplastic fiber, effectively disperses the material stress, and effectively improves the rigidity strength of the automobile interior ceiling, so that the automobile interior ceiling can maintain excellent self-supporting performance under different environmental conditions, ensuring the stability of size and appearance.

[0025] 2. The method of the present application adopts a dry preparation process, using only one set of molds to complete the substrate molding and fabric compounding. The composite material is easy to recycle and reuse after scrap processing and the end of its life cycle. There is no solvent volatilization in the production process, realizing a low-carbon, environmentally friendly, and low-VOC green production process.

[0026] 3. The method of the present application adopts a punching method to remove excess scraps and wrap the skylight substrate and the fabric as a whole, reducing the cutting and tearing processes, improving efficiency while also ensuring the stability of the vehicle assembly size and reducing product defects caused by the cutter cutting the fabric or the cutter not being smooth. DETAILED DESCRIPTION

[0027] The following examples further illustrate the present application in detail. raw material

[0028] Unless otherwise specified, the raw materials used in the examples and comparative examples of this application are all commercially available products, specifically: Hemicellulase, enzyme activity is 100,000 u / mL; Bamboo fiber, filament, diameter 15±3mm, linear density 25±3tex; Polypropylene granules, selected from Formosa Plastics Polypropylene, PP3090; Glass fiber, formed by chopped alkali-free E-glass untwisted stranded glass fiber yarn with a diameter of 10 μm and a linear density of 2400 tex; Polypropylene fiber, 50D, length 3-5mm; Polyethylene fiber, 50D, length 3-5mm; Polyester fiber, PET fiber, 20D, length 3-5mm; ES fiber is PE / PP fiber with a linear density of 0.2-0.3dtex and a length of 2-5mm. Preparation example of bottom nonwoven fabric

[0029] Preparation Example 1 The bottom layer is non-woven fabric, with a gram weight of 30±5g / m 2 It is made of a composite fiber with a skin-core structure, the skin layer is modified polypropylene fiber, and the core layer is modified bamboo fiber, wherein the mass ratio of modified polypropylene fiber to modified bamboo fiber is 3:7.

[0030] The method for preparing the bottom nonwoven fabric comprises the following steps: S1: dissolving hemicellulase in water, adjusting the solution pH to 4.5, adding bamboo fiber filaments, wherein the mass of the hemicellulase is 0.06% of the mass of the bamboo fiber filaments, soaking for 0.5 h at 35° C., taking out and drying, to obtain modified bamboo fiber filaments; S2: 10 parts by weight of polypropylene particles and 1.5 parts by weight of maleic anhydride are uniformly mixed, 0.35 parts by weight of dicumyl peroxide are added and blended, and the mixture is added into a screw extruder, and melt grafting reaction is carried out at 240° C. and 75 r / min for 15 min, and then modified polypropylene fiber filaments are obtained after melt spinning, stretching and heat setting; S3: Distributing the modified polypropylene fiber filaments in parallel and uniformly on the surface of the modified bamboo fiber filaments, and then twisting and compounding them according to a twist of 300 twists / m and an S twist direction to obtain composite fibers; S4: Cutting the composite fibers to form short fibers, opening, mixing, combing, web laying and needle punching the short fibers to obtain short fibers.

[0031] Preparation Example 2 The bottom nonwoven fabric is different from that of Preparation Example 1 in that its preparation method comprises the following steps: S1: dissolving hemicellulase in water, adjusting the solution pH to 5, adding bamboo fiber filaments, wherein the mass of the hemicellulase is 0.06% of the mass of the bamboo fiber filaments, soaking at 40° C. for 1 h, taking out and drying, to obtain modified bamboo fiber filaments; S2: 10 parts by weight of polypropylene particles and 2 parts by weight of maleic anhydride are uniformly mixed, 0.35 parts by weight of dicumyl peroxide are added and blended, and the mixture is added into a screw extruder, and melt grafting reaction is carried out at 240° C. and 75 r / min for 15 min, and then modified polypropylene fiber filaments are obtained after melt spinning, stretching and heat setting; S3: Distributing the modified polypropylene fiber filaments in parallel and uniformly on the surface of the modified bamboo fiber filaments, and then twisting and compounding them according to a twist of 400 twists / m and an S twist direction to obtain composite fibers; S4: Cutting the composite fibers to form short fibers, opening, mixing, combing, web laying and needle punching the short fibers to obtain short fibers.

[0032] Preparation Example 3 The bottom nonwoven fabric is different from that of Preparation Example 1 in that its preparation method comprises the following steps: S1: dissolving hemicellulase in water, adjusting the solution pH to 5.5, adding bamboo fiber filaments, wherein the mass of the hemicellulase is 0.06% of the mass of the bamboo fiber filaments, soaking at 50° C. for 1.5 h, taking out and drying, to obtain modified bamboo fiber filaments; S2: 10 parts by weight of polypropylene particles and 2.5 parts by weight of maleic anhydride are uniformly mixed, 0.35 parts by weight of dicumyl peroxide are added and blended, and the mixture is added into a screw extruder, and melt grafting reaction is carried out at 240° C. and 75 r / min for 15 min, and then modified polypropylene fiber filaments are obtained after melt spinning, stretching and heat setting; S3: Distributing the modified polypropylene fiber filaments in parallel and uniformly on the surface of the modified bamboo fiber filaments, and then twisting and compounding them according to a twist of 500 twists / m and a Z twist direction to obtain composite fibers; S4: Cutting the composite fibers to form short fibers, opening, mixing, combing, web laying and needle punching the short fibers to obtain short fibers.

[0033] Preparation Example 4 The bottom nonwoven fabric is different from that in Preparation Example 1 in that it is made of composite fibers with a skin-core structure, wherein the skin layer is polypropylene fiber and the core layer is modified bamboo fiber, wherein the mass ratio of polypropylene fiber to modified bamboo fiber is 3:7.

[0034] The method for preparing the bottom nonwoven fabric comprises the following steps: S1: dissolving hemicellulase in water, adjusting the solution pH to 4.5, adding bamboo fiber filaments, wherein the mass of the hemicellulase is 0.06% of the mass of the bamboo fiber filaments, soaking for 0.5 h at 35° C., taking out and drying, to obtain modified bamboo fiber filaments; S2: using polypropylene particles as raw materials, melt spinning, stretching and heat setting to obtain polypropylene fiber filaments, distributing the polypropylene fiber filaments parallel and evenly on the surface of the modified bamboo fiber filaments, and then twisting and compounding them according to a twist of 300 twists / m and an S twist direction to obtain composite fibers; S4: Cutting the composite fibers to form short fibers, opening, mixing, combing, web laying and needle punching the short fibers to obtain short fibers.

[0035] Preparation Example 5 The bottom nonwoven fabric is different from that of Preparation Example 1 in that its preparation method comprises the following steps: S1: dissolving hemicellulase in water, adjusting the solution pH to 4.5, adding bamboo fiber filaments, wherein the mass of the hemicellulase is 0.06% of the mass of the bamboo fiber filaments, soaking for 0.5 h at 35° C., taking out and drying, to obtain modified bamboo fiber filaments; S2: 10 parts by weight of polypropylene particles and 1.5 parts by weight of maleic anhydride are uniformly mixed, 0.35 parts by weight of dicumyl peroxide are added and blended, and the mixture is added into a screw extruder, and melt grafting reaction is carried out at 240° C. and 75 r / min for 15 min, and then modified polypropylene fiber filaments are obtained after melt spinning, stretching and heat setting; S3: cutting modified polypropylene fiber filaments and modified bamboo fiber filaments to form short fibers, and opening, mixing, combing, web laying and needle punching the short fibers to obtain short fibers, wherein the mass ratio of modified polypropylene fiber to modified bamboo fiber is 3:7. Example Example 1

[0036] A fiber-reinforced thermoplastic composite automotive interior ceiling comprises a substrate and a fabric, wherein the substrate comprises, from bottom to top, a bottom non-woven fabric, a first adhesive film, a blended fiber felt, and a second adhesive film, wherein the bottom non-woven fabric is obtained by Preparation Example 1; the blended fiber felt is made of reinforcing fibers and thermoplastic fibers in a mass ratio of 1:0.85, the reinforcing fibers are glass fibers formed by chopped alkali-free E-glass untwisted stranded glass fiber yarns with a diameter of 10 μm and a linear density of 2400 tex, and the thermoplastic fibers are polypropylene fibers and ES fibers in a mass ratio of 1:1.

[0037] The method for preparing the fiber-reinforced thermoplastic composite automotive interior ceiling comprises the following steps: S1: After opening, mixing, combing, laying and needle punching glass fiber and thermoplastic fiber, a blended fiber felt is obtained; 10 parts by weight of polypropylene particles are uniformly mixed with 1.5 parts by weight of maleic anhydride, and then 0.1 parts by weight of diisopropylbenzene peroxide are added to blend, and the blend is added to a screw extruder, and melt grafting reaction is carried out at 240°C and 70r / min for 15 minutes, and a polypropylene film is obtained after extrusion and film formation, and cooling and curing to form a first adhesive film and a second adhesive film; a bottom non-woven fabric, a first adhesive film, a blended fiber felt and a second adhesive film are laid in sequence, and a substrate is obtained after preheating, heating, plate making and cooling, and the surface density of the obtained substrate is 950g / m 2 , thickness is 4mm, of which the mass of the blended fiber felt is 40% of the mass of the base material; S2: The substrate is heated to a surface temperature of 200°C. The robot places the skylight reinforcement frame into the corresponding pit of the lower mold from the X direction. The fabric is automatically transferred to the middle position of the upper and lower molds from the Y direction. The heated substrate is automatically transferred to the middle position of the upper and lower molds from the -Y direction and is located below the fabric. The temperature of the upper and lower molds is 15°C. The upper mold automatically falls and is molded at a molding pressure of 60 bar for 30 seconds to obtain a preliminary shape of the ceiling. S3: Put the ceiling prototype into the punching die and position it according to the shape of the skylight. The holding pressure of the punching press is 200 bar and the holding time is 5 seconds. The punching die is provided with a floating press plate and a cold die and a cold knife. The cold die and the cold knife punch out the redundant side holes to obtain the ceiling prototype. S4: The skylight base material and fabric of the ceiling base are rolled and covered as a whole. Example 2

[0038] A fiber-reinforced thermoplastic composite automobile interior ceiling, which differs from Example 1 in that the bottom non-woven fabric is obtained by Preparation Example 2; the blended fiber felt is made of reinforcing fibers and thermoplastic fibers in a mass ratio of 1:1, and the thermoplastic fibers are polyethylene fibers and ES fibers in a mass ratio of 1:1.

[0039] The method for preparing the fiber-reinforced thermoplastic composite automotive interior ceiling comprises the following steps: S1: After opening, mixing, combing, laying and needle punching glass fiber and thermoplastic fiber, a blended fiber felt is obtained; 10 parts by weight of polypropylene particles are uniformly mixed with 1.5 parts by weight of maleic anhydride, and then 0.1 parts by weight of diisopropylbenzene peroxide are added to blend, and the blend is added to a screw extruder, and melt grafting reaction is carried out at 240°C and 70r / min for 15 minutes, and a polypropylene film is obtained after extrusion and film formation, and cooling and curing to form a first adhesive film and a second adhesive film; a bottom non-woven fabric, a first adhesive film, a blended fiber felt and a second adhesive film are laid in sequence, and a substrate is obtained after preheating, heating, plate making and cooling, and the surface density of the obtained substrate is 800g / m 2 , thickness is 4.5mm, of which the mass of the blended fiber felt is 35% of the mass of the base material; S2: The substrate is heated to a surface temperature of 170°C. The robot places the skylight reinforcement frame into the corresponding pit of the lower mold from the X direction. The fabric is automatically transferred to the middle position of the upper and lower molds from the Y direction. The heated substrate is automatically transferred to the middle position of the upper and lower molds from the -Y direction and is located below the fabric. The temperature of the upper and lower molds is 20°C. The upper mold automatically falls and is molded at a molding pressure of 40 bar for 33 seconds to obtain a preliminary shape of the ceiling. S3: Put the ceiling prototype into the punching die and position it according to the shape of the skylight. The holding pressure of the punching press is 190 bar and the holding time is 7 seconds. The punching die is provided with a floating press plate and a cold die and a cold knife. The cold die and the cold knife punch out the redundant side holes to obtain the ceiling base form. S4: The skylight base material and fabric of the ceiling base are rolled and covered as a whole. Example 3

[0040] A fiber-reinforced thermoplastic composite automobile interior ceiling, which differs from Example 1 in that the bottom non-woven fabric is obtained by Preparation Example 3; the blended fiber felt is made of reinforcing fibers and thermoplastic fibers in a mass ratio of 1:1.15, and the thermoplastic fibers are polyester fibers and ES fibers in a mass ratio of 1:1.

[0041] The method for preparing the fiber-reinforced thermoplastic composite automotive interior ceiling comprises the following steps: S1: After opening, mixing, combing, laying and needle punching glass fiber and thermoplastic fiber, a blended fiber felt is obtained; 10 parts by weight of polypropylene particles are uniformly mixed with 1.5 parts by weight of maleic anhydride, and then 0.1 parts by weight of diisopropylbenzene peroxide are added to blend, and the blend is added to a screw extruder, and melt grafting reaction is carried out at 240°C and 70r / min for 15 minutes, and a polypropylene film is obtained after extrusion and film formation, and cooling and curing to form a first adhesive film and a second adhesive film; a bottom non-woven fabric, a first adhesive film, a blended fiber felt and a second adhesive film are laid in sequence, and a substrate is obtained after preheating, heating, plate making and cooling, and the surface density of the obtained substrate is 1000g / m 2 , thickness is 3.5mm, of which the mass of the blended fiber felt is 45% of the mass of the base material; S2: The substrate is heated to a surface temperature of 210°C. The robot places the skylight reinforcement frame into the corresponding pit of the lower mold from the X direction. The fabric is automatically transferred to the middle position of the upper and lower molds from the Y direction. The heated substrate is automatically transferred to the middle position of the upper and lower molds from the -Y direction and is located below the fabric. The temperature of the upper and lower molds is 10°C. The upper mold automatically falls and is molded at a molding pressure of 40 bar for 27 seconds to obtain a preliminary shape of the ceiling. S3: Put the ceiling prototype into the punching die and position it according to the shape of the skylight. The holding pressure of the punching press is 210 bar and the holding time is 3 seconds. The punching die is provided with a floating press plate and a cold die and a cold knife. The cold die and the cold knife punch out the redundant side holes to obtain the ceiling prototype. S4: The skylight base material and fabric of the ceiling base are rolled and covered as a whole. Example 4

[0042] A fiber-reinforced thermoplastic composite material automobile interior ceiling, which is different from Example 1 in that the bottom non-woven fabric is obtained by Preparation Example 4, and the surface density of the substrate obtained in step S1 is 950 g / m 2 , with a thickness of 4 mm, wherein the mass of the blended fiber felt is 40% of the mass of the substrate, and the other steps are the same as in Example 1. Example 5

[0043] A fiber-reinforced thermoplastic composite material automobile interior ceiling, which is different from Example 1 in that the bottom non-woven fabric is obtained from Preparation Example 5, and the surface density of the substrate obtained in step S1 is 950 g / m 2 , with a thickness of 4 mm, wherein the mass of the blended fiber felt is 40% of the mass of the substrate, and the other steps are the same as in Example 1. Example 6

[0044] A fiber-reinforced thermoplastic composite automotive interior ceiling, which is different from Example 1 in that the bottom non-woven fabric is a PET non-woven fabric with a gram weight of 30±5g / m 2The other steps are the same as those in Example 1. In step S1, the surface density of the substrate is 950 g / m 2 , with a thickness of 4.2 mm, wherein the mass of the blended fiber felt is 40% of the mass of the substrate, and the other steps are the same as in Example 1. Comparative Example

[0045] Comparative Example 1 A fiber-reinforced thermoplastic composite automobile interior ceiling, which differs from Example 1 in that a blended fiber felt is made of reinforcing fibers and thermoplastic fibers in a mass ratio of 1:0.8, the mass of the blended fiber felt is 40% of the mass of the substrate, and other steps are the same as those in Example 1.

[0046] Comparative Example 2 A fiber-reinforced thermoplastic composite automobile interior ceiling, which differs from Example 1 in that a blended fiber felt is made of reinforcing fibers and thermoplastic fibers in a mass ratio of 1:1.2, the mass of the blended fiber felt is 40% of the mass of the substrate, and other steps are the same as those in Example 1. Performance testing

[0047] The fiber reinforced thermoplastic composite automotive interior ceilings obtained in Examples 1-6 and Comparative Examples 1-2 were subjected to the following relevant performance test tests, each set of tests was performed 3 times, the average value of the 3 test results was taken as the final result, and the experimental results were recorded in Table 1.

[0048] 1. The fiber-reinforced thermoplastic composite automotive interior ceiling substrates obtained in Examples 1-6 and Comparative Examples 1-2 were placed under environmental conditions of (50±2)°C and 90% relative humidity for 24 hours and then subjected to tests on flexural strength and flexural modulus.

[0049] 2. The fiber-reinforced thermoplastic composite automotive interior ceiling substrates obtained in Examples 1-6 and Comparative Examples 1-2 were heated at 205° C. for 2 min and then the free expansion height of the substrates was measured.

[0050] 3. Referring to the standards and regulations of PV3900, the odor levels of the fiber-reinforced thermoplastic composite automotive interior ceilings obtained in Examples 1-6 and Comparative Examples 1-2 were tested.

[0051] Table 1

[0052] According to the performance test results in Table 1, it can be seen that the fiber-reinforced thermoplastic composite automotive interior ceiling prepared by the preparation method of the present application has low odor, and the preparation process is low-carbon and environmentally friendly, meeting the requirements of green production. The ceiling substrate can still maintain excellent rigidity under high temperature and high humidity conditions, with longitudinal bending strength ≥31.95N / 50mm, transverse bending strength ≥31.02N / 50mm, longitudinal bending modulus ≥1323.54Mpa, and transverse bending modulus ≥1221.21Mpa, which shows that the fiber-reinforced thermoplastic composite automotive interior ceiling of the present application can adapt to environmental changes, always maintain good self-supporting performance, and ensure stable size and appearance.

[0053] The free expansion height of the fiber-reinforced thermoplastic composite material automobile interior ceiling substrate of the present application after being heated at 205°C for 2.5 minutes is not less than 8 mm, which means that it has excellent thermoplasticity and is easy to process and shape. It can significantly improve the adhesion between the automobile ceiling fabric and the substrate, improve the yield rate, shorten the production cycle, and meet the requirements of large-scale production. At the same time, it is also easy to recycle after the life cycle of the ceiling, which reduces costs and is more environmentally friendly and sustainable.

[0054] According to the performance test results of Examples 1-3 and Comparative Examples 1-2, it can be seen that the blended fiber felt prepared by using reinforcing fibers and thermoplastic fibers combines the high strength and high modulus of alkali-free E glass fibers with the high flexibility and easy processing performance of thermoplastic fibers. The two can exert the best synergistic effect at a mass ratio of 1: (0.85-1.15), ensuring the molding and structural integrity of the board, effectively dispersing material stress, improving the rigidity and thermoplasticity of the automobile interior ceiling substrate, and ensuring that the automobile interior ceiling maintains excellent dimensional stability under different environmental conditions.

[0055] According to the performance test results of Examples 1-3 and 4-6, it can be seen that compared with the traditional PET bottom non-woven fabric for preparing the automobile ceiling substrate, the present application adopts a skin-core structure composite fiber with modified bamboo fiber as the core layer and modified polypropylene fiber as the skin layer to prepare the bottom non-woven fabric. On the one hand, it is easier to recycle and reuse in the subsequent process, which is more environmentally friendly. On the other hand, it also significantly improves the rigidity of the automobile interior ceiling substrate, thereby ensuring the dimensional stability of the automobile interior ceiling in different environments. After the polypropylene fiber is grafted with maleic anhydride, it has better compatibility with bamboo fiber, which is conducive to further improving the mechanical properties of the bottom non-woven fabric and further ensuring the stability of the automobile interior ceiling.

[0056] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A fiber-reinforced thermoplastic composite automotive interior ceiling, comprising a substrate and a fabric, characterized in that: The substrate is composed of a bottom non-woven fabric, a first adhesive film, a blended fiber felt and a second adhesive film from bottom to top; the blended fiber felt is made of reinforcing fibers and thermoplastic fibers in a mass ratio of 1:(0.85-1.15) through a non-woven process; The bottom nonwoven fabric is formed by twisting and compounding modified bamboo fibers obtained by hemicellulase modification and modified polypropylene fibers obtained by maleic anhydride modification, and then opening, mixing, combing, laying and needle punching the composite fibers.

2. The fiber-reinforced thermoplastic composite automotive interior ceiling according to claim 1, characterized in that: The reinforcing fibers are glass fibers, which are formed by chopped alkali-free E-glass untwisted stranded glass fiber yarns with a diameter of 10 μm and a linear density of 2400 tex.

3. The fiber-reinforced thermoplastic composite automotive interior ceiling according to claim 1, characterized in that: The thermoplastic fiber is any one or more combinations of polypropylene fiber, polyethylene fiber, polyester fiber and ES fiber.

4. The fiber-reinforced thermoplastic composite automotive interior ceiling according to claim 1, characterized in that: The first adhesive film and the second adhesive film are both maleic anhydride-modified polypropylene films.

5. The fiber-reinforced thermoplastic composite automotive interior ceiling according to claim 1, characterized in that: The bottom non-woven fabric is made of composite fibers with a core-skin structure, the core layer of the composite fibers is modified bamboo fibers, and the skin layer of the composite fibers is modified polypropylene fibers.

6. The fiber-reinforced thermoplastic composite automotive interior ceiling according to claim 5, characterized in that: The method for preparing the bottom nonwoven fabric comprises the following steps: S1: dissolving hemicellulase in water and adjusting the pH of the solution to 4.5-5.5, adding bamboo fiber filaments, soaking at 35-50° C. for 0.5-1.5 h, taking out and drying to obtain modified bamboo fiber filaments; S2: mixing polypropylene particles and maleic anhydride in a mass ratio of 10:(1.5-2.5), adding dicumyl peroxide to blend, adding to a screw extruder for melt grafting reaction, and then melt spinning, stretching and heat setting to obtain modified polypropylene fiber filaments; S3: Distributing the modified polypropylene fiber filaments in parallel and uniformly on the surface of the modified bamboo fiber filaments, and then twisting and compounding them according to a twist of 300-500 twists / m and an S twist or a Z twist to obtain a composite fiber; S4: Cutting the composite fibers to form short fibers, opening, mixing, combing, web laying and needle punching the short fibers to obtain short fibers.

7. A method for preparing a fiber-reinforced thermoplastic composite automotive interior ceiling according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: opening, mixing, combing, laying and needle punching glass fiber and thermoplastic fiber to obtain a blended fiber felt; laying a bottom non-woven fabric, a first adhesive film, a blended fiber felt and a second adhesive film in sequence, and obtaining a substrate after preheating, heating, plate making and cooling; S2: The substrate is heated to a surface temperature of 190±20°C, the robot puts the skylight reinforcement frame into the corresponding pit of the lower mold, the fabric is automatically transferred to the middle position of the upper and lower molds, the substrate is automatically transferred to the middle position of the upper and lower molds and is located below the fabric, the upper mold automatically falls, and the pressure is maintained to form, and the initial shape of the ceiling is obtained; S3: placing the preliminary form of the ceiling into a punching die, and positioning it according to the shape of the skylight window. The holding pressure of the punching press is 200±10 bar, and the holding time is 5±2s. The punching die is provided with a floating press plate and a cold die and a cold knife. The cold die and the cold knife punch out the redundant side holes to obtain the basic form of the ceiling. S4: The skylight base material and fabric of the ceiling base are rolled and covered as a whole.

8. The method for preparing the fiber-reinforced thermoplastic composite automotive interior ceiling according to claim 7, characterized in that: The surface density of the substrate obtained in step S1 is 800-1000 g / m 2 , thickness is 4±0.5mm.

9. The method for preparing the fiber-reinforced thermoplastic composite automotive interior ceiling according to claim 8, characterized in that: The mass of the blended fiber felt is 40±5% of the mass of the substrate.

10. The method for preparing the fiber reinforced thermoplastic composite automotive interior ceiling according to claim 7, characterized in that: In step S2, the pressure-holding molding conditions are: the temperature of the upper and lower molds is 15±5°C, the molding pressure is 50±10 bar, and the pressure-holding time is 30±3s.

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