A fiber-reinforced thermoplastic composite automotive interior ceiling and its preparation method

Abstract

This application relates to the technical field of automotive ceiling production, and specifically discloses a fiber-reinforced thermoplastic composite automotive interior ceiling and a preparation method thereof. A fiber-reinforced thermoplastic composite automotive interior ceiling includes a base material and a fabric. The base material sequentially comprises a bottom non-woven fabric, a first bonding film, a blended fiber felt, and a second bonding film from bottom to top. The blended fiber felt is made of reinforcing fibers and thermoplastic fibers through a non-woven process. The preparation method is as follows: after dry-preparing the base material, a set of molds is used to complete the forming of the skeleton and the composite of the fabric to obtain a ceiling prototype, and then it is obtained through cold die cutting and overall hemming and wrapping of the base material and the fabric at the skylight opening. The fiber-reinforced thermoplastic composite automotive interior ceiling of this application has excellent dimensional stability, is more low-carbon and environmentally friendly, and the raw material scraps generated during the production process and after the end of the product life cycle are easy to recycle.

Description

Technical Field

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

[0002] The automotive ceiling is an interior part of the vehicle located above the passenger cabin. It is an important component that combines decoration and functionality in the driver's cab of the vehicle. Its main functions are to improve the decoration in the cab, absorb interior noise, insulate from the outside heat, protect the heads of passengers, and enhance the comfort and safety of the driver and passengers.

[0003] In addition, during the driving process of the vehicle, the automotive ceiling needs to maintain good self-supporting performance and good matching effects with surrounding components such as columns and skylights to ensure reasonable lap fit during assembly and good appearance after assembly. Therefore, the selection of automotive ceiling materials and the preparation process are particularly important. As an important part of automotive interiors, the automotive ceiling plays an indispensable role in enhancing the competitiveness of vehicles.

[0004] Regarding the above related technologies, the inventor found that the vast majority of passenger vehicle automotive ceilings on the market mainly use a two-step wet process ceiling with a PU structure. This requires two sets of hot molds for the forming of the skeleton and the lamination of the fabric respectively, and the production process relies on liquid glue. This not only easily causes the production environment to be dirty and messy, increasing the cleaning difficulty, but also increases the odor of the finished ceiling materials. In addition, there are also problems of high technical difficulty and high cost in the treatment of scraps during the production process of PU structure composites and the recycling after the end of the product life cycle. Summary of the Invention

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

[0006] In a first aspect, the present application provides a fiber-reinforced thermoplastic composite automotive interior ceiling, adopting the following technical solution:

[0007] A fiber-reinforced thermoplastic composite automotive interior ceiling, comprising a base material and a fabric. The base material is successively composed of a bottom non-woven fabric, a first bonding film, a blended fiber felt, and a second bonding film from bottom to top; the blended fiber felt is made by a non-woven process from reinforcing fibers and thermoplastic fibers with a mass ratio of 1:(0.85 - 1.15).

[0008] By adopting the above technical solutions, the introduction of the blended fiber mat, the reinforcing fibers provide high strength and rigidity, while the thermoplastic fibers have good flexibility and processing performance. The two types of fibers are blended to prepare the blended fiber mat, and the material has good processing and forming performance, significantly enhancing the overall strength, rigidity and anti-deformation ability of the automotive interior ceiling, and ensuring that the automotive interior ceiling still maintains excellent self-supporting performance in high-temperature and high-humidity environments.

[0009] Optionally, the reinforcing fibers are glass fibers, which are formed by short-cutting an alkali-free E glass untwisted ply glass fiber yarn with a diameter of 10 μm and a linear density of 2400 tex.

[0010] Optionally, the thermoplastic fibers are any one or a combination of polypropylene fibers, polyethylene fibers, polyester fibers and ES fibers.

[0011] Optionally, both the first adhesive film and the second adhesive film are maleic anhydride-modified polypropylene adhesive films.

[0012] Optionally, the bottom non-woven fabric is made of composite fibers with a core-shell structure. The core layer of the composite fibers is modified bamboo fibers, and the skin layer of the composite fibers is modified polypropylene fibers.

[0013] By adopting the above technical solutions, bamboo fiber is a natural plant fiber with the characteristics of being renewable and degradable. After forming composite fibers with polypropylene fibers to prepare the bottom non-woven fabric, it is easier to be recycled and processed after the end of the life cycle of the automotive interior ceiling, meeting the requirements of environmental protection and sustainable development. Moreover, bamboo fiber is light in weight and has natural antibacterial properties, making it more hygienic, and can further realize the lightweight of the automotive interior ceiling, promoting the achievement of energy-saving and carbon-reduction goals.

[0014] Both bamboo fiber and polypropylene fiber have excellent strength and toughness. Using modified bamboo fiber as the core layer and modified polypropylene fiber as the skin layer to prepare composite fibers with a core-shell structure has higher strength and toughness, which can further improve the strength of the substrate of the automotive interior ceiling and ensure the self-supporting performance of the prepared automotive interior ceiling in different environments.

[0015] In addition, related materials such as polypropylene and polyethylene used in the bottom non-woven fabric, the first adhesive film, the blended fiber mat and the second adhesive film are polyolefin polymers. Using modified polypropylene fiber as the skin layer to coat the bamboo fiber to form composite fibers to prepare non-woven fabric has better compatibility with the upper adhesive film and the blended fiber mat, which can significantly promote the improvement of the interfacial bonding force, and then ensure the enhancement of the rigidity of the prepared automotive interior ceiling.

[0016] Optionally, the preparation method of the bottom non-woven fabric includes the following steps:

[0017] S1: Dissolve hemicellulase in water, adjust the pH of the solution to 4.5 - 5.5, add bamboo fiber filaments, soak them at 35 - 50 °C for 0.5 - 1.5 h, take them out and dry to obtain modified bamboo fiber filaments;

[0018] S2: Mix polypropylene particles and maleic anhydride evenly according to a mass ratio of 10:(1.5 - 2.5), add dicumyl peroxide for blending, add them into a screw extruder for melt grafting reaction, and then obtain modified polypropylene fiber filaments after melt spinning, drawing and heat setting;

[0019] S3: Distribute the modified polypropylene fiber filaments evenly and parallelly on the surface of the modified bamboo fiber filaments, and then perform twisting and compounding treatment according to a twist of 300 - 500 turns / meter in the S twist or Z twist direction to obtain composite fibers;

[0020] S4: Cut the composite fibers into short fibers, and then obtain the product after loosening, mixing, carding, web laying and needling the short fibers.

[0021] By adopting the above technical solutions, the modification of bamboo fibers by hemicellulase treatment and the modification of polypropylene fibers grafted with maleic anhydride can effectively improve the compatibility between the skin-core fibers. The composite fibers with a skin-core structure are obtained through twisting and compounding treatment, significantly improving the structural stability and mechanical properties of the bottom non-woven fabric, providing a reliable bottom layer for the automotive interior ceiling, and further ensuring the self-supporting performance of the automotive interior ceiling under different environmental conditions.

[0022] In the second aspect, the present application provides a method for preparing an automotive interior ceiling made of a fiber-reinforced thermoplastic composite material, adopting the following technical solutions:

[0023] A method for preparing an automotive interior ceiling made of a fiber-reinforced thermoplastic composite material, comprising the following steps:

[0024] S1: Obtain a blended fiber mat by loosening, mixing, carding, web laying and needling glass fibers and thermoplastic fibers; successively lay the bottom non-woven fabric, the first bonding film, the blended fiber mat and the second bonding film, and obtain a substrate after preheating, heating, plate making and cooling;

[0025] S2: Heat the substrate to a surface temperature of 190 ± 20 °C, the manipulator places the skylight reinforcement frame into the corresponding pit of the lower mold, the fabric is automatically fed into the middle position between the upper and lower molds, the substrate is automatically fed into the middle position between the upper and lower molds and is located below the fabric, and the upper mold automatically drops and is pressure-molded to obtain a preliminary ceiling;

[0026] S3: Place the initial ceiling form into a punching die, position it using the shape of the skylight opening. The holding pressure of the punching press is 200 ± 10 bar, and the holding time is 5 ± 2 s. The punching die is equipped with a floating pressure plate and has a cold die and cold knife. After the cold die and cold knife cut off the excess side holes, a ceiling base form is obtained.

[0027] S4: Integrally curl and wrap the substrate and fabric of the skylight opening of the ceiling base form, and it is ready.

[0028] By adopting the above technical solution, using a dry manufacturing process, only one set of dies is used to complete the skeleton forming and fabric lamination. The prepared substrate has good free expansion performance after heating, and has excellent rigidity, can maintain good stability under high temperature and high humidity conditions, and can meet the production requirements of a ceiling with a thickness of 4 - 6 mm.

[0029] In the traditional dry ceiling industry, when using a robot water cutting method for edge cutting and punching, the cutting time for each piece is 35 - 55 seconds, and the dimensional tolerance of the ceiling holes after cutting is ±1 mm. However, the method of this application uses a punching die for cutting, and the cutting time for each piece is only 3 - 7 seconds, and the dimensional tolerance of the ceiling holes after cutting can be controlled within ±0.5 mm. This significantly improves the production efficiency of automotive interior ceiling manufacturing, and at the same time ensures the stability of the overall vehicle assembly dimensions.

[0030] The preparation process of this 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. It is a green production process for sustainable development.

[0031] Optionally, the basis weight of the substrate obtained in step S1 is 800 - 1000 g / m 2 , and the thickness is 4 ± 0.5 mm.

[0032] Optionally, the mass of the blended fiber mat is 40 ± 5% of the mass of the substrate.

[0033] Optionally, in step S2, the conditions for pressure holding and forming are: the temperatures of the upper and lower dies are 15 ± 5 °C, the forming pressure is 50 ± 10 bar, and the pressure holding time is 30 ± 3 s.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. Since this application uses a blended fiber mat of reinforcing fibers and thermoplastic fibers to prepare the ceiling substrate, combining the high strength and high modulus of alkali-free E glass fibers, and the high flexibility and easy processing performance of thermoplastic fibers, effectively dispersing the material stress, effectively improving the rigid strength of the automotive interior ceiling, enabling the automotive interior ceiling to maintain excellent self-supporting performance under different environmental conditions, and ensuring stable dimensions and appearance.

[0036] 2. The method of the present application adopts a dry preparation process, and only one set of molds is used to complete the forming of the base material and the lamination of the fabric. The composite material is easy to recycle and reuse after the treatment of the scraps and at the end of its life cycle. There is no solvent volatilization during the production process, realizing a green production process with low carbon, environmental protection and low VOC.

[0037] 3. The method of the present application uses a punching method to remove the excess scraps, and the base material of the skylight opening and the fabric are integrally edge-wrapped, reducing the processes of cutting knives and tearing edges. While improving the efficiency, it also ensures the stability of the overall vehicle assembly dimensions, and reduces the product defects caused by the fabric being cut by the cutting knife or the cutting knife being not smooth. Specific Embodiments

[0038] The following embodiments further illustrate the present application in detail.

[0039] Raw Materials

[0040] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present application are all commercially available products, specifically:

[0041] Hemicellulase, with an enzyme activity of 100,000 u / mL;

[0042] Bamboo fiber, filament, with a diameter of 15 ± 3 mm and a linear density of 25 ± 3 tex;

[0043] Polypropylene particles, selected from Formosa Plastics polypropylene, PP3090;

[0044] Glass fiber, formed by short-cutting an alkali-free E glass untwisted ply fiberglass yarn with a diameter of 10 μm and a linear density of 2400 tex;

[0045] Polypropylene fiber, 50D, with a length of 3 - 5 mm;

[0046] Polyethylene fiber, 50D, with a length of 3 - 5 mm;

[0047] Polyester fiber, PET fiber, 20D, with a length of 3 - 5 mm;

[0048] ES fiber, PE / PP fiber, with a linear density of 0.2 - 0.3 dtex and a length of 2 - 5 mm.

[0049] Preparation Example of the Bottom Nonwoven Fabric

[0050] Preparation Example 1

[0051] The bottom nonwoven fabric, with a grammage of 30 ± 5 g / m 2 , is made of composite fibers with a skin-core structure. The skin layer is modified polypropylene fiber, and the core layer is modified bamboo fiber, where the mass ratio of the modified polypropylene fiber to the modified bamboo fiber is 3:7.

[0052] The preparation method of the above-mentioned bottom non-woven fabric comprises the following steps:

[0053] S1: Dissolve hemicellulase in water, adjust the pH of the solution to 4.5, add bamboo fiber filaments, wherein the mass of hemicellulase is 0.06% of the mass of the bamboo fiber filaments, soak for 0.5 h at 35°C, take out and dry to obtain modified bamboo fiber filaments;

[0054] S2: Mix 10 parts by weight of polypropylene particles with 1.5 parts by weight of maleic anhydride evenly, add 0.35 parts by weight of dicumyl peroxide for blending, add into a screw extruder, carry out a melt grafting reaction at 240°C and a rotation speed of 75 r / min for 15 min, and then obtain modified polypropylene fiber filaments after melt spinning, stretching and heat setting;

[0055] S3: Evenly distribute the modified polypropylene fiber filaments parallel on the surface of the modified bamboo fiber filaments, and then carry out a twisting and compounding treatment according to a twist of 300 turns / m and an S twist direction to obtain composite fibers;

[0056] S4: Cut the composite fibers into short fibers, and obtain the product after loosening, mixing, carding, web laying and needling the short fibers.

[0057] Preparation Example 2

[0058] The bottom non-woven fabric, different from Preparation Example 1, its preparation method comprises the following steps:

[0059] S1: Dissolve hemicellulase in water, adjust the pH of the solution to 5, add bamboo fiber filaments, wherein the mass of hemicellulase is 0.06% of the mass of the bamboo fiber filaments, soak for 1 h at 40°C, take out and dry to obtain modified bamboo fiber filaments;

[0060] S2: Mix 10 parts by weight of polypropylene particles with 2 parts by weight of maleic anhydride evenly, add 0.35 parts by weight of dicumyl peroxide for blending, add into a screw extruder, carry out a melt grafting reaction at 240°C and a rotation speed of 75 r / min for 15 min, and then obtain modified polypropylene fiber filaments after melt spinning, stretching and heat setting;

[0061] S3: Evenly distribute the modified polypropylene fiber filaments parallel on the surface of the modified bamboo fiber filaments, and then carry out a twisting and compounding treatment according to a twist of 400 turns / m and an S twist direction to obtain composite fibers;

[0062] S4: Cut the composite fibers into short fibers, and obtain the product after loosening, mixing, carding, web laying and needling the short fibers.

[0063] Preparation Example 3

[0064] The bottom non-woven fabric, different from Preparation Example 1, its preparation method includes the following steps:

[0065] S1: Dissolve hemicellulase in water, adjust the pH of the solution to 5.5, add bamboo fiber filaments, wherein the mass of hemicellulase is 0.06% of the mass of bamboo fiber filaments, soak at 50 °C for 1.5 h, take out and dry to obtain modified bamboo fiber filaments;

[0066] S2: Mix 10 parts by weight of polypropylene particles with 2.5 parts by weight of maleic anhydride evenly, add 0.35 parts by weight of diisopropylbenzene peroxide for blending, add into a screw extruder, carry out melt grafting reaction at 240 °C and a rotation speed of 75 r / min for 15 min, and then obtain modified polypropylene fiber filaments after melt spinning, stretching and heat setting;

[0067] S3: Distribute the modified polypropylene fiber filaments evenly and parallel on the surface of the modified bamboo fiber filaments, and then carry out twisting and compounding treatment according to a twist of 500 twists / meter and a Z-twist direction to obtain composite fibers;

[0068] S4: Cut the composite fibers into short fibers, and obtain the product after loosening, mixing, carding, web laying and needling the short fibers.

[0069] Preparation Example 4

[0070] The bottom non-woven fabric, different from Preparation Example 1, is made of composite fibers with a skin-core structure, 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.

[0071] The preparation method of the above bottom non-woven fabric includes the following steps:

[0072] S1: Dissolve hemicellulase in water, adjust the pH of the solution to 4.5, add bamboo fiber filaments, wherein the mass of hemicellulase is 0.06% of the mass of bamboo fiber filaments, soak at 35 °C for 0.5 h, take out and dry to obtain modified bamboo fiber filaments;

[0073] S2: Use polypropylene particles as raw materials to obtain polypropylene fiber filaments after melt spinning, stretching and heat setting. Distribute the polypropylene fiber filaments evenly and parallel on the surface of the modified bamboo fiber filaments, and then carry out twisting and compounding treatment according to a twist of 300 twists / meter and an S-twist direction to obtain composite fibers;

[0074] S4: Cut the composite fibers into short fibers, and obtain the product after loosening, mixing, carding, web laying and needling the short fibers.

[0075] Preparation Example 5

[0076] The bottom non-woven fabric, different from Preparation Example 1 in its preparation method, includes the following steps:

[0077] S1: Dissolve hemicellulase in water, adjust the pH of the solution to 4.5, add bamboo fiber filaments, where the mass of hemicellulase is 0.06% of the mass of bamboo fiber filaments, soak at 35 °C for 0.5 h, take out and dry to obtain modified bamboo fiber filaments;

[0078] S2: Mix 10 parts by weight of polypropylene particles with 1.5 parts by weight of maleic anhydride evenly, add 0.35 parts by weight of dicumyl peroxide for blending, add into a screw extruder, and carry out a melt grafting reaction at 240 °C and a rotation speed of 75 r / min for 15 min, and then obtain modified polypropylene fiber filaments after melt spinning, stretching and heat setting;

[0079] S3: Cut the modified polypropylene fiber filaments and the modified bamboo fiber filaments into short fibers, and obtain them after loosening, mixing, carding, web laying and needling. The mass ratio of the modified polypropylene fiber to the modified bamboo fiber is 3:7. Example Example 1

[0080] A fiber-reinforced thermoplastic composite automotive interior ceiling, including a substrate and a fabric. The substrate is successively from bottom to top a bottom non-woven fabric, a first bonding film, a blended fiber felt and a second bonding film. Among them, the bottom non-woven fabric is obtained from Preparation Example 1; the blended fiber felt is made of reinforcing fibers and thermoplastic fibers with a mass ratio of 1:0.85. The reinforcing fibers are glass fibers, which are short cut from an alkali-free E glass untwisted ply fiberglass yarn with a diameter of 10 μm and a linear density of 2400 tex. The thermoplastic fibers are polypropylene fibers and ES fibers with a mass ratio of 1:1.

[0081] The preparation method of the above fiber-reinforced thermoplastic composite automotive interior ceiling includes the following steps:

[0082] S1: Obtain a blended fiber felt by loosening, mixing, carding, web laying and needling the glass fibers and thermoplastic fibers; Mix 10 parts by weight of polypropylene particles with 1.5 parts by weight of maleic anhydride evenly, then add 0.1 parts by weight of dicumyl peroxide for blending, add the blend into a screw extruder, and carry out a melt grafting reaction at 240 °C and a rotation speed of 70 r / min for 15 min, extrude into a film, cool and solidify to obtain a polypropylene adhesive film, and form a first bonding film and a second bonding film; Lay the bottom non-woven fabric, the first bonding film, the blended fiber felt and the second bonding film in sequence, and obtain a substrate after preheating, heating, plate making and cooling. The areal density of the obtained substrate is 950 g / m 2 , with a thickness of 4 mm, where the mass of the blended fiber felt is 40% of the mass of the substrate;

[0083] S2: Heat the substrate to a surface temperature of 200 °C. The manipulator places the skylight reinforcement frame into the corresponding pit of the lower mold in the X direction. The fabric is automatically fed into the middle position between the upper and lower molds in the Y direction. The heated substrate is automatically fed into the middle position between the upper and lower molds in the -Y direction and is located below the fabric. The temperatures of the upper and lower molds are 15 °C. The upper mold automatically drops, and it is held under pressure at 60 bar for 30 s to form, obtaining the initial roof lining;

[0084] S3: Place the initial roof lining into the punching die, position it using the shape of the skylight opening. The holding pressure of the punching press is 200 bar, and the holding time is 5 s. The punching die is equipped with a floating pressure plate and has cold dies and cold knives. After the cold dies and cold knives cut off the excess side holes, the basic roof lining is obtained;

[0085] S4: Integrally crimp and wrap the substrate and fabric at the skylight opening of the basic roof lining, and it is ready. Example 2

[0086] A fiber-reinforced thermoplastic composite automotive interior roof lining, different from Example 1 in that the bottom non-woven fabric is obtained from Preparation Example 2; the blended fiber mat is made of reinforcing fibers and thermoplastic fibers with a mass ratio of 1:1, and the thermoplastic fibers are polyethylene fibers and ES fibers with a mass ratio of 1:1.

[0087] The preparation method of the above fiber-reinforced thermoplastic composite automotive interior roof lining includes the following steps:

[0088] S1: Obtain a blended fiber mat by opening, mixing, carding, laying, and needling glass fibers and thermoplastic fibers; Mix 10 parts by weight of polypropylene particles and 1.5 parts by weight of maleic anhydride evenly, then add 0.1 part by weight of dicumyl peroxide for blending. Add the blend into a screw extruder and carry out a melt grafting reaction at 240 °C and a rotation speed of 70 r / min for 15 min. After extrusion into a film and cooling and solidifying, a polypropylene adhesive film is obtained to form the first adhesive film and the second adhesive film; Lay the bottom non-woven fabric, the first adhesive film, the blended fiber mat, and the second adhesive film in sequence, and after preheating, heating, plate making, and cooling, a substrate is obtained. The areal density of the obtained substrate is 800 g / m 2 , with a thickness of 4.5 mm, where the mass of the blended fiber mat is 35% of the mass of the substrate;

[0089] S2: Heat the substrate to a surface temperature of 170 °C. The manipulator places the skylight reinforcement frame into the corresponding pit of the lower mold in the X direction. The fabric is automatically fed into the middle position between the upper and lower molds in the Y direction. The heated substrate is automatically fed into the middle position between the upper and lower molds in the -Y direction and is located below the fabric. The temperatures of the upper and lower molds are 20 °C. The upper mold automatically drops, and it is held under pressure at 40 bar for 33 s to form, obtaining the initial roof lining;

[0090] S3: Place the initial roof form into the punching die, position it using the shape of the skylight opening. The holding pressure of the punching press is 190 bar and the holding time is 7 s. The punching die is equipped with a floating pressure plate and has a cold die and cold knife. After the cold die and cold knife cut off the excess side holes, the basic roof form is obtained;

[0091] S4: Perform overall hemming and wrapping on the skylight opening base material and fabric of the basic roof form, and it is ready. Example 3

[0092] A fiber-reinforced thermoplastic composite automotive interior roof, different from Example 1 in that the bottom non-woven fabric is obtained from Preparation Example 3; the blended fiber felt is made of reinforcing fibers and thermoplastic fibers with a mass ratio of 1:1.15, and the thermoplastic fibers are polyester fibers and ES fibers with a mass ratio of 1:1.

[0093] The preparation method of the above-mentioned fiber-reinforced thermoplastic composite automotive interior roof includes the following steps:

[0094] S1: Obtain a blended fiber felt by opening, mixing, carding, laying, and needling glass fibers and thermoplastic fibers; mix 10 parts by weight of polypropylene particles with 1.5 parts by weight of maleic anhydride evenly, then add 0.1 part by weight of dicumyl peroxide for blending, add the blend into a screw extruder, and carry out a melt grafting reaction at 240 °C and a rotation speed of 70 r / min for 15 min. After extrusion into a film and cooling and curing, a polypropylene adhesive film is obtained to form a first adhesive film and a second adhesive film; lay the bottom non-woven fabric, the first adhesive film, the blended fiber felt, and the second adhesive film in sequence, and after preheating, heating, plate making, and cooling, a base material is obtained. The areal density of the obtained base material is 1000 g / m 2 , with a thickness of 3.5 mm, and the mass of the blended fiber felt is 45% of the mass of the base material;

[0095] S2: Heat the base material to a surface temperature of 210 °C. The manipulator places the skylight reinforcement frame into the corresponding pit of the lower die in the X direction, the fabric is automatically fed into the middle position between the upper and lower dies in the Y direction, the heated base material is automatically fed into the middle position between the upper and lower dies in the -Y direction and is located below the fabric. The temperatures of the upper and lower dies are 10 °C, the upper die automatically drops, and it is formed under a forming pressure of 40 bar and held for 27 s to obtain the initial roof form;

[0096] S3: Place the initial roof form into the punching die, position it using the shape of the skylight opening. The holding pressure of the punching press is 210 bar and the holding time is 3 s. The punching die is equipped with a floating pressure plate and has a cold die and cold knife. After the cold die and cold knife cut off the excess side holes, the basic roof form is obtained;

[0097] S4: Perform overall hemming and wrapping on the skylight opening base material and fabric of the basic roof form, and it is ready. Example 4

[0098] A fiber-reinforced thermoplastic composite automotive interior ceiling, which is different from that of Example 1 in that the bottom non-woven fabric is obtained from Preparation Example 4, and the areal 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 mat is 40% of the mass of the substrate, and the other steps are the same as those in Example 1. Example 5

[0099] A fiber-reinforced thermoplastic composite automotive interior ceiling, which is different from that of Example 1 in that the bottom non-woven fabric is obtained from Preparation Example 5, and the areal 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 mat is 40% of the mass of the substrate, and the other steps are the same as those in Example 1. Example 6

[0100] A fiber-reinforced thermoplastic composite automotive interior ceiling, which is different from that of Example 1 in that the bottom non-woven fabric is a PET non-woven fabric with a grammage of 30 ± 5 g / m 2 , and the other steps are the same as those in Example 1. The areal density of the substrate obtained in Step S1 is 950 g / m 2 , with a thickness of 4.2 mm, wherein the mass of the blended fiber mat is 40% of the mass of the substrate, and the other steps are the same as those in Example 1. Comparative Example

[0101] Comparative Example 1

[0102] A fiber-reinforced thermoplastic composite automotive interior ceiling, which is different from that of Example 1 in that the blended fiber mat is made of reinforcing fibers and thermoplastic fibers with a mass ratio of 1:0.8, and the mass of the blended fiber mat is 40% of the mass of the substrate, and the other steps are the same as those in Example 1.

[0103] Comparative Example 2

[0104] A fiber-reinforced thermoplastic composite automotive interior ceiling, which is different from that of Example 1 in that the blended fiber mat is made of reinforcing fibers and thermoplastic fibers with a mass ratio of 1:1.2, and the mass of the blended fiber mat is 40% of the mass of the substrate, and the other steps are the same as those in Example 1.

[0105] Performance detection test

[0106] The fiber-reinforced thermoplastic composite automotive interior ceilings obtained in Examples 1-6 and Comparative Examples 1-2 are respectively subjected to the following relevant performance detection tests. Each group of tests is carried out 3 times, and the average value of the 3 test results is taken as the final result, and the experimental results are recorded in Table 1.

[0107] 1. The fiber-reinforced thermoplastic composite automotive interior ceiling substrates obtained in Examples 1-6 and Comparative Examples 1-2 were placed in an environment of (50±2)°C and 90% relative humidity for 24 h, and then the flexural strength and flexural modulus were tested respectively.

[0108] 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.

[0109] 3. Referring to the standards and regulations of PV3900, the odor grades of the fiber-reinforced thermoplastic composite automotive interior ceilings obtained in Examples 1-6 and Comparative Examples 1-2 were detected.

[0110] Table 1

[0111]

[0112] It can be seen from the performance test results in Table 1 that a 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 a longitudinal flexural strength ≥ 31.95 N / 50 mm, a transverse flexural strength ≥ 31.02 N / 50 mm, a longitudinal flexural modulus ≥ 1323.54 Mpa, and a transverse flexural modulus ≥ 1221.21 Mpa. This shows that a 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 dimensions and appearance.

[0113] The free expansion height of the fiber-reinforced thermoplastic composite automotive interior ceiling substrate of the present application after heating at 205°C for 2.5 min is not less than 8 mm, which shows that it has excellent thermoplasticity, is easy to process and form, can significantly improve the adhesion between the automotive ceiling fabric and the substrate, improve the yield rate, shorten the production cycle, meet the requirements of large-scale production, and at the same time, it is also easy to recycle after the end of the ceiling life cycle, reducing costs and being more environmentally friendly and sustainable.

[0114] It can be seen from the performance test results of Examples 1-3 and Comparative Examples 1-2 that the blended fiber mat prepared by using reinforcing fibers and thermoplastic fibers combines the high strength and high modulus of E-glass fiber without alkali and the high flexibility and easy processing performance of thermoplastic fibers. The two can play the best synergistic effect at a combination ratio of 1:(0.85-1.15) in terms of mass ratio, ensuring the forming and structural integrity of the plate, effectively dispersing the material stress, improving the rigidity strength and thermoplasticity of the fiber-reinforced thermoplastic composite automotive interior ceiling substrate, and ensuring excellent dimensional stability of the automotive interior ceiling under different environmental conditions.

[0115] From the performance test results of Examples 1-3 and Examples 4-6, it can be seen that compared with the traditional PET bottom non-woven fabric for preparing the automotive ceiling substrate, the bottom non-woven fabric of the present application is prepared from a core-sheath structured composite fiber with modified bamboo fiber as the core layer and modified polypropylene fiber as the sheath layer. On the one hand, it is more conducive to subsequent recycling and reuse, and is more environmentally friendly. On the other hand, it also significantly improves the rigidity strength of the automotive interior ceiling substrate, thereby ensuring the dimensional stability of the automotive interior ceiling in different environments. After graft modification of polypropylene fiber with maleic anhydride, the compatibility with bamboo fiber is better, which is beneficial to further improve the mechanical properties of the bottom non-woven fabric and further ensure the stability of the automotive interior ceiling.

[0116] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

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 first adhesive film and the second adhesive film are both maleic anhydride-modified polypropylene films; the bottom non-woven fabric is a core layer of modified bamboo fibers modified by hemicellulase and a skin layer of modified polypropylene fibers modified by maleic anhydride, and is twisted and composited to obtain a composite fiber with a skin-core structure, and then opened, mixed, combed, laid and needled. The preparation method of the bottom non-woven 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 fiber to form short fibers, and opening, mixing, combing, laying and needle punching the short fibers to obtain short fibers; The surface density of the substrate is 800-1000 g / m 2 , thickness: 4±0.5mm; The mass of the blended fiber felt is 40±5% of the mass of the substrate.

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 method for preparing a fiber-reinforced thermoplastic composite automotive interior ceiling according to any one of claims 1 to 3, 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: Place the ceiling prototype into the punching die and position it using the shape of the skylight. The holding pressure of the punching press is 200±10 bar, and the holding time is 5±2s. The punching die is equipped with a floating press plate and a cold die cold Knife, cold die and cold knife punch out the extra side holes to get the base shape of the ceiling; S4: The skylight base material and fabric of the ceiling base are rolled and covered as a whole.

5. The method for preparing the fiber-reinforced thermoplastic composite automotive interior ceiling according to claim 4, 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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