A composite material for an automobile ceiling and a preparation method thereof

Abstract

This application relates to the field of composite boards, and specifically discloses a composite material for an automobile ceiling and a preparation method thereof. A composite material for an automobile ceiling is characterized by sequentially including a bottom non-woven fabric, a lower film adhesive, a PP fiber / glass fiber mat, a barrier layer, an upper film adhesive, and a fabric layer. The barrier layer is made by compression molding and compounding a PP film adhesive, a maleic anhydride-modified PP film, a PA film, a maleic anhydride-modified PP film, and a PP film adhesive that are sequentially in contact. The PP glass fiber board of this application can effectively prevent the fabric layer of the automobile ceiling from generating mottles, improve the appearance quality of the automobile ceiling, and at the same time has high bending resistance, noise reduction, and sound absorption effects.

Description

Technical Field

[0001] The present application relates to the technical field of composite materials, and more specifically, to a composite material for an automobile ceiling and a preparation method thereof. Background Art

[0002] With the current development trend of the automotive interior industry towards high performance, environmental protection, low carbon, and low VOC, the requirements for automobile ceilings are also getting higher and higher. The automobile ceiling is a crucial structural component of the whole vehicle's interior trim. In addition to internal decoration, it can effectively play roles such as heat insulation and sound insulation.

[0003] An automobile ceiling generally consists of a fabric layer, a substrate layer, and a back non-woven fabric layer. Among them, the fabric layer faces the passengers and reflects the appearance effect of the ceiling. Generally, non-woven fabrics, knitted fabrics, PVC films, etc. are used. The substrate layer is the main determinant of other properties of the ceiling except for the appearance performance. Generally, PU fiberglass boards, PP fiberglass composite boards, corrugated cardboard, hemp fiber boards, etc. are used. The PP fiberglass composite board has advantages such as lightweight, low odor, and low VOC, and its application in automotive interior products is becoming more and more extensive, enabling car owners to obtain a more comfortable riding environment.

[0004] The current substrate structure composition of the PP fiberglass composite board is: a bottom non-woven fabric, a bottom adhesive film, a PP fiberglass mat, and an upper adhesive film. Then, the upper adhesive film is in contact with and adhered to the non-woven fabric layer of the ceiling. During the forming process of the board, since the four sides of the automobile ceiling are mostly curved structures, the upper adhesive film has a large deformation during hot pressing and lamination, resulting in the upper adhesive film being prone to breakage, causing the auxiliaries (such as antioxidants, etc.) in the PP fiberglass mat to emit outward, and finally adhering to the surface of the fabric layer on the front of the automobile ceiling, thus resulting in a mottled problem similar to white spots on the surface of the automobile ceiling, affecting the appearance quality of the automobile ceiling. Summary of the Invention

[0005] In order to prevent the auxiliaries in the PP fiberglass mat of the PP fiberglass composite board from emitting outward, which causes mottling on the surface of the automobile ceiling and affects its appearance quality, the present application provides a composite material for an automobile ceiling and a preparation method thereof.

[0006] In a first aspect, the present application provides a composite material for an automobile ceiling, adopting the following technical solution:

[0007] A composite material for an automobile ceiling sequentially includes a bottom non-woven fabric, a lower adhesive film, a PP fiber / glass fiber mat, a barrier layer, an upper adhesive film, and a fabric layer. The barrier layer is made by molding and laminating a PP adhesive film, a maleic anhydride modified PP film, a PA film, a maleic anhydride modified PP film, and a PP adhesive film in sequence.

[0008] By adopting the above technical solution, a barrier layer is arranged between the PP fiber / glass fiber felt and the upper adhesive film. When the upper adhesive film and the fabric layer are molded, the upper adhesive film is hot-melted to bond the fabric layer, and the barrier layer can play a protective role, which can prevent the additives in the PP fiber / glass fiber felt from emitting to the fabric layer through the damaged parts of the upper adhesive film, thereby reducing the mottling phenomenon on the car roof.

[0009] The outermost layer of the barrier layer is PP film, which can be bonded to the PP fiber / glass fiber felt and the upper film respectively. The PP film close to the upper film can play a bonding and protective agent diffusion effect when the upper film is damaged by hot pressing. The maleic anhydride modified PP film can improve the compatibility of the PP film and the PA film during hot melt bonding during compression molding, thereby improving the bonding strength between the PP film and the PA film, thereby obtaining a barrier layer with tightly bonded layers. The PA film can effectively block the penetration of small molecular substances such as antioxidants, thereby reducing the problem of car roof mottle caused by the penetration of antioxidants and other additives.

[0010] Optionally, the barrier layer has a thickness of 0.12-0.15 mm.

[0011] By adopting the above technical solution, a barrier layer of this thickness can effectively reduce the penetration of additives such as antioxidants in the PP fiber / glass fiber mat into the fabric layer, while providing a certain amount of mechanical strength for the PP glass fiber board.

[0012] Optionally, the PP fiber / glass fiber mat contains PP fibers and glass fibers in a mass ratio of 1:1.

[0013] By adopting the above technical solution and using appropriate PP fiber and glass fiber to prepare PP fiber / glass fiber mat, the tensile strength and bending modulus of the composite fiber mat are higher, the material is harder and tougher, and the performance remains stable at high temperatures. In addition, the shrinkage rate of the material is reduced and the dimensional stability is improved.

[0014] Optionally, the preparation method of the PP fiber / glass fiber mat is as follows:

[0015] The glass fiber is immersed in silica sol, taken out and immersed in an anhydrous ethanol solution of graphene oxide, ultrasonicated at a power of 250-300W for 100-120min, then dried at 50-55°C under normal pressure, and needled to obtain a matrix felt;

[0016] The polypropylene and cellulose acetate butyrate are mixed in a mass ratio of 1:0.1-0.2, and the mixture is melt-spun after vacuum drying. The spun product is extracted at 60-65° C. for 20-24 hours using acetone as a solvent to obtain PP fiber.

[0017] Disperse PP fibers into a polyacrylamide solution to prepare a suspension. Pour the suspension onto a matrix felt, followed by vacuum filtration and drying to obtain a PP fiber / glass fiber felt.

[0018] By adopting the above technical solution, impregnate glass fibers with silica sol. Utilize the viscosity of the silica sol to adhere graphene oxide. After drying at atmospheric pressure, the silica sol coated on the glass fibers forms silica aerogel, which has a rich porosity and thus good sound absorption performance. The porous structure enables sound waves to move back and forth. The air movement near the pore walls is fast and slow. When air propagates in the internal pores of the material, due to the vibration of the sound wave, the viscosity of the air particles will generate a corresponding viscous force, causing the sound energy to be converted into heat energy, thereby resulting in the attenuation of the sound wave and achieving the purpose of absorbing sound waves. A large number of hydroxyl groups present on the surface of graphene oxide can undergo a condensation reaction with the silanol groups of the glass fibers and the silica sol, thus firmly binding the graphene oxide to the surface of the glass fibers and making it difficult to peel off from the glass fibers. After adding graphene oxide, it can adhere to the surface and voids of the glass fibers. When a sound wave enters the material, the air in the pores of the material vibrates due to the entry of the sound wave. At the same time, graphene oxide vibrates with the glass fibers under the action of the sound wave and air vibration. During this process, the sound energy is converted into mechanical energy and heat energy, dissipating part of the sound energy, thereby reducing the intensity of the sound wave passing through and improving the sound absorption ability of the sound wave. Moreover, the graphene oxide flakes are evenly distributed on the surface and voids of the glass fibers, forming more voids inside the material and increasing the internal surface area of the material, resulting in more friction between the sound wave and the fibers and graphene oxide, and converting the sound wave into heat loss through the viscous friction and heat conduction of the glass fibers and the surrounding graphene oxide microstructure, and quickly transferring and releasing the heat to the outside through the high thermal conductivity graphene oxide, thereby improving the sound absorption performance of the material.

[0019] At the same time, graphene oxide can also coat the surface of the glass fibers to form a dense graphene oxide film. Due to the functional group interaction between the two, a strong interfacial bonding force can be formed, which can improve the rigidity of the glass fibers. This increase in rigidity makes the glass fibers less likely to deform or break when subjected to external forces, hindering the propagation of cracks on the surface of the glass fibers, thereby improving the mechanical strength of the glass fibers and further enhancing the bending resistance effect of the fiber felt.

[0020] Prepare polypropylene fibers by the melt phase separation method. Due to the dissolution of cellulose acetate butyrate, it has a micro-nano structure and thus obtains a sound absorption effect. Disperse the polypropylene fibers with a polyacrylamide solution and then pour them onto a matrix felt. The polypropylene fibers overlap with each other on the matrix felt, obtaining a high porosity, thereby improving the sound absorption and noise reduction effect of the PP fiber / glass fiber felt.

[0021] Optionally, the lower layer adhesive film comprises polypropylene resin and a sound absorption enhancer in a mass ratio of 1:0.1 - 0.2.

[0022] By adopting the above technical solution, adding a certain amount of sound absorption enhancer to the polypropylene resin can endow the lower layer adhesive film with certain noise reduction and sound absorption effects.

[0023] Optionally, the preparation method of the sound absorption enhancer is as follows:

[0024] Mix PET chips with PBT resin and calcium carbonate, melt and spin them to obtain PET fibers. Immerse the PET fibers in a hydrochloric acid solution with a concentration of 5.5 - 6wt% for 20 - 24h, filter, wash, and dry them to obtain the sound absorption enhancer. The mass ratio of PET chips, PBT resin, and calcium carbonate is 1:0.1 - 0.15:0.03 - 0.05.

[0025] By adopting the above technical solution, after the PET fibers made by mixing PET chips with PBT resin and calcium carbonate and then spinning are immersed in the hydrochloric acid solution, calcium carbonate dissolves out from the fibers, forming more macroscopic micropores. Although the mechanical strength of the fibers will be reduced to a certain extent, the PET fibers will have certain sound absorption and noise reduction effects. And PBT resin has good compatibility with PET. When blended and spun, it can accelerate the crystallization rate and form some copolymers, thereby improving the mechanical properties of PET fibers. Moreover, PET fibers have high heat resistance. Therefore, after the prepared sound absorption enhancer is added to the polypropylene resin and blended with the polypropylene resin to prepare the adhesive film, the fiber shape will not melt and disappear, and it can further improve the mechanical strength of the polypropylene adhesive film in the polypropylene adhesive film.

[0026] Optionally, the preparation method of the upper layer adhesive film is as follows:

[0027] Mix polypropylene resin, EPDM particles, and nano-silica in a mass ratio of 1:0.3 - 0.4:0.04 - 0.06 evenly, then extrude and pelletize, and injection mold. Heat press at 185 - 190°C for 4 - 5min, heat at 175 - 180°C for 20 - 30s, then stretch at a speed of 480 - 500mm / min to 0.03 - 0.04mm, and then cool down to 140 - 145°C at a speed of 15 - 20°C / min, and keep the temperature for heat treatment for 50 - 60min.

[0028] By adopting the above technical solutions, nano-silica plays a role of heterogeneous nucleation in polypropylene, refining the crystal grains, increasing the crystallization temperature, accelerating the crystallization rate, effectively improving the toughness of the polypropylene film, and improving the tensile strength and bending properties of the polypropylene film. The EPDM particles have good compatibility with the polypropylene resin, enabling the EPDM to be evenly dispersed in the polypropylene matrix and form a tight bond, thereby improving the toughness of the polypropylene film. When the upper polypropylene film is thermocompression laminated with the fabric layer, the EPDM can absorb and disperse energy, effectively preventing the polypropylene film from cracking. Moreover, after mixing and pelletizing the polypropylene resin with EPDM and nano-silica, the hot-pressed product is subjected to hot stretching - cooling - annealing heat treatment, so that the polypropylene film has a high initial modulus and a high elastic recovery rate. The blend melt of the polypropylene resin and EPDM crystallizes under a high tensile stress field to obtain good melt orientation, thereby forming lamellae arranged parallel in the stress direction, and thus having good hard elasticity. The melt tensile curve of the hot-pressed product rises smoothly when heated at 175 - 180 °C, which not only ensures the melting of polypropylene, etc., but also has a certain strength. The force acting on the melt forms a melt orientation, and crystallization can occur on the oriented melt during cooling to obtain a good tensile strength. Heat treatment at 140 - 145 °C uses high temperature to increase the activity of molecular chains, and the crystallization is perfected through the adjustment of molecular chains, thereby increasing the crystallinity, increasing the lamella thickness, increasing the resilience, and enhancing the tensile strength. Therefore, the polypropylene film is not easily cracked due to a large amount of deformation during hot melting, thus avoiding the phenomenon of mottling on the fabric layer.

[0029] Optionally, the bottom non-woven fabric is one of spunlace non-woven fabric, spunbond non-woven fabric or hot-rolled non-woven fabric.

[0030] By adopting the above technical solutions, spunlace non-woven fabric, spunbond non-woven fabric, etc. can not only increase the comfort of the car roof, but also have good air permeability, wear resistance, wash resistance and high strength, and can increase comfort and durability.

[0031] In a second aspect, the present application provides a preparation method of a composite material for a car roof, adopting the following technical solutions:

[0032] A preparation method of a composite material for a car roof includes the following steps:

[0033] Mix maleic anhydride grafted polypropylene and polypropylene resin, extrude and pelletize, and cast to obtain maleic anhydride modified PP film;

[0034] Bond the PP film, maleic anhydride modified PP film, PA film, maleic anhydride modified PP film and PP film in sequence, and perform die pressing and lamination to form a barrier layer;

[0035] The bottom non-woven fabric, lower film, PP fiber / glass fiber mat, barrier layer, upper film and fabric layer are sequentially laminated in order, hot-pressed into shape, cooled and cut to obtain a PP fiberglass board.

[0036] By adopting the above technical solution, maleic anhydride grafted polypropylene is mixed with polypropylene resin and initiator and then cast to obtain a maleic anhydride modified PP film. Then, it is molded with a PP film and a PA film in order to obtain a barrier layer. Then, the bottom non-woven fabric, lower film, etc. are hot-pressed into shape in order to obtain a fiberglass board with strong overall stability and not easily generating mottles.

[0037] Optionally, the temperature of the molding compound is 160 - 170 °C and the time is 30 - 40 s;

[0038] The temperature of the hot pressing into shape is 150 - 160 °C and the time is 35 - 45 s.

[0039] In summary, the present application has the following beneficial effects:

[0040] 1. Since a barrier layer is provided between the PP fiber / glass fiber mat and the upper film in the present application, and the barrier layer is made of a PP film, a maleic anhydride modified PP film, a PA film, a maleic anhydride modified PP film and a PP film. The PP film located on the outermost layer plays a bonding role and is bonded to the PP fiber / glass fiber mat and the upper film respectively. The maleic anhydride modified PP film improves the hot melt compatibility of the PA film and the PP film, making the bonding more tight and the overall stability of the barrier layer better. The PA layer plays a role in preventing the diffusion and penetration of small molecules such as auxiliaries, preventing the auxiliaries in the PP fiber / glass fiber mat from passing through the upper film damaged by hot pressing and forming mottles on the automotive ceiling fabric layer, and can improve the appearance quality of the automotive ceiling.

[0041] 2. In the present application, it is preferably to impregnate silica sol and graphene oxide on the glass fiber in sequence, use polypropylene resin and cellulose acetate butyrate to prepare PP fibers with micro-nano pores, and then disperse the PP fibers and pour them on the matrix mat formed by the glass fiber to be able to make a PP fiber / glass fiber mat with a strong adsorption effect on noise.

[0042] 3. In the present application, it is preferably to use PET chips, PBT resin and calcium carbonate to mix and spin and then impregnate with hydrochloric acid solution to prepare a sound absorption enhancer, and then mix it with polypropylene resin to prepare the lower film. The fiber form of the sound absorption enhancer can improve the mechanical strength of the lower film, thereby enhancing the bending resistance of the fiberglass board and further enhancing the noise reduction effect of the fiberglass board.

[0043] 4. In this application, it is preferably to prepare the lower-layer PP film by mixing polypropylene resin with EPDM and nano-silica, granulating, injection molding, and heat stretching-cooling-annealing treatment, so as to further improve the toughness, bending resistance, etc. of the lower-layer PP film. Therefore, when the upper-layer PP film is hot-pressed and compounded with the automotive ceiling fabric layer, it is not easy to be damaged due to a large deformation amount, and thus the phenomenon of the automotive fabric layer generating mottles can also be further prevented. Detailed implementation mode

[0044] The following examples further illustrate this application in detail.

[0045] Preparation examples 1-6 of PP fiber / glass fiber felt

[0046] In the following preparation examples, the silica sol is selected from Xuancheng Jingrui New Materials Co., Ltd., with the model number VK-S01B, the graphene oxide is selected from Shanghai Xiangtian Nano Materials Co., Ltd., with the model number XT-GO, the glass fiber is selected from Tai'an Hongtong New Materials Co., Ltd., with the product number 03 and a length of 12 mm, the polypropylene is selected from Dongguan Shenghe Plastics, with the brand number 1102L, the cellulose acetate butyrate is selected from Shenzhen Yiponuo Chemical Industry, with the model number CAB-381-20, and the polyacrylamide is selected from Henan Saike Environmental Protection Technology, with a molecular weight of 3 million.

[0047] Preparation example 1: Mix 50 g of glass fiber and 50 g of PP fiber evenly, and needle-punch to obtain a PP fiber / glass fiber felt with a thickness of 1 mm. The polypropylene fiber is a commercially available product, selected from Shandong Changgu Engineering Materials Co., Ltd., with the product number A01.

[0048] Preparation example 2: (1) Immerse 50 g of glass fiber in the silica sol, take it out and immerse it in an anhydrous ethanol solution of graphene oxide with a concentration of 0.3 wt%, ultrasonicate at a power of 250 W for 120 min, and then dry it at normal pressure at 55 °C for 24 h, and needle-punch to obtain a matrix felt;

[0049] (2) Mix polypropylene and cellulose acetate butyrate according to a mass ratio of 1:0.2, vacuum dry at 100 °C for 24 h and then melt-spin. Use acetone as the solvent for the spun fiber, extract at 60 °C for 24 h to remove the cellulose acetate butyrate in the spun fiber, and obtain PP fibers with a length of 60 mm. The melt-spinning temperature is 200 °C, the extrusion rate is 100 r / min, and the stretching frequency is 3 Hz;

[0050] (3) Disperse 50 g of PP fiber into 70 g of a polyacrylamide solution with a concentration of 0.1% to obtain a suspension, pour the suspension onto the matrix felt, vacuum filter, and dry at 60 °C to obtain a PP fiber / glass fiber felt with a thickness of 1 mm.

[0051] Preparation Example 3: (1) Immerse 50 g of glass fiber in silica sol, take it out and then immerse it in an absolute ethanol solution of graphene oxide with a concentration of 0.3 wt%, ultrasonicate it at a power of 300 W for 100 min, and then dry it at normal pressure at 50 °C for 24 h, and needling is carried out to obtain a matrix felt;

[0052] (2) Mix polypropylene and cellulose acetate butyrate in a mass ratio of 1:0.1, vacuum dry it at 100 °C for 24 h and then carry out melt spinning. Use acetone as the solvent for the spun product, extract it at 65 °C for 20 h to remove cellulose acetate butyrate in the spun product, and obtain PP fibers with a length of 65 mm. The melt spinning temperature is 200 °C, the extrusion rate is 100 r / min, and the stretching frequency is 3 Hz;

[0053] (3) Disperse 50 g of PP fibers into 60 g of a polyacrylamide solution with a concentration of 0.1% to obtain a suspension, pour the suspension onto the matrix felt, carry out vacuum filtration, and dry it at 60 °C to obtain a PP fiber / glass fiber felt with a thickness of 1 mm.

[0054] Preparation Example 4: The difference from Preparation Example 2 is that the glass fiber is not immersed in silica sol and is directly immersed in an absolute ethanol solution of graphene oxide with a concentration of 0.3 wt%.

[0055] Preparation Example 5: The difference from Preparation Example 2 is that the glass fiber is not immersed in silica sol and is not immersed in an absolute ethanol solution of graphene oxide with a concentration of 0.3 wt%. The glass fiber is directly needled to obtain a matrix felt of 120 g / m 2 .

[0056] Preparation Example 6: The difference from Preparation Example 2 is that the PP fiber is a commercially available product, selected from Shandong Changgu Engineering Materials Co., Ltd., and the product number is A01.

[0057] Preparation Examples 7-10 of Sound Absorbing Reinforcing Agent

[0058] In the following preparation examples, the PET chips are selected from Shanghai Yuanyang, model CH-610, and the PBT resin is selected from Dongguan Juxinheng Rubber and Plastic Co., Ltd., grade 325-1001.

[0059] Preparation Example 7: Mix 100 g of PET chips, 15 g of PBT resin, and 5 g of calcium carbonate, melt and spin them at 295 °C to obtain PET fibers, immerse them in a 5.5 wt% hydrochloric acid solution for 24 h, filter, wash, and dry them to obtain sound absorbing reinforcing agents with a length of 5 mm. When spinning, the extrusion voltage is 70 V, the winding speed is 80 m / min, the spinneret has 6 holes, and the hole diameter is 0.3 mm.

[0060] Preparation Example 8: 100 g of PET chips were mixed with 10 g of PBT resin and 3 g of calcium carbonate, melted and spun at 295 °C to obtain PET fibers, which were impregnated in a 6 wt% hydrochloric acid solution for 20 h, filtered, washed and dried to obtain a sound-absorbing and reinforcing agent with a length of 5 mm. The extrusion voltage during spinning was 70 V, the winding speed was 80 m / min, the spinneret had 6 holes, and the hole diameter was 0.3 mm.

[0061] Preparation Example 9: The difference from Preparation Example 7 is that the PET fibers were not impregnated in the hydrochloric acid solution.

[0062] Preparation Example 10: The difference from Preparation Example 7 is that no PBT resin was added. Example

[0063] In the following examples, the polypropylene resin was selected from Henan Yueqi New Materials Co., Ltd., with the product number PC-GW200, the maleic anhydride grafted polypropylene was selected from Dow Chemical Company, USA, with the model BYNEL50E662, the EPDM particles were selected from Shanghai Jiuqing Chemical Industry, with the brand 3702, the PP film with a thickness of 0.03 mm was selected from Dongguan Bailingsi Plastic Technology Co., Ltd., with the brand B-09091 and the product number BLS-BM-040101, the PP film with a thickness of 0.04 mm was selected from Chaozhou Chao'an Wanxingshun Packaging, with the product number 36, the PA film was selected from Suzhou Hanruisi New Materials Technology Co., Ltd., with the product number XJA110, and the thickness was 0.05 mm.

[0064] Example 1: A composite material for automotive ceiling, which sequentially includes a bottom non-woven fabric, a lower film, a PP fiber / glass fiber mat, a barrier layer, an upper film and a fabric layer from bottom to top. The fabric layer is a spunlace non-woven fabric with a thickness of 0.7 mm, the bottom non-woven fabric is a spunlace PET non-woven fabric with a thickness of 0.7 mm, both the upper film and the lower film are PP films, the PP fiber / glass fiber mat is made from Preparation Example 1, and the barrier layer includes PP films, maleic anhydride modified PP films, PA films, maleic anhydride modified PP films and PP films that are sequentially laminated, and the thickness of each PP film is 0.04 mm.

[0065] The preparation method of the above composite material for automotive ceiling includes the following steps:

[0066] The polypropylene resin and maleic anhydride grafted polypropylene were mixed evenly according to the mass percentage of 60% and 40%, heated to melting and extruded into pellets, and after hot melt calendaring at 220 °C, a maleic anhydride modified PP film with a thickness of 0.04 mm was obtained;

[0067] The PP film, maleic anhydride modified PP film, PA film, maleic anhydride modified PP film and PP film were sequentially laminated and compression molded to obtain a barrier layer with a thickness of 0.15 mm. The temperature of the compression molding was 170 °C and the time was 40 s;

[0068] The spunlace PET non-woven fabric, PP film, PP fiber / glass fiber mat, barrier layer, PP film and fabric layer are laminated in sequence, cooled and cut after hot pressing and forming, to obtain a PP glass fiber board with a thickness of 2.2 mm. The hot pressing and forming temperature is 160 °C and the time is 35 s.

[0069] Example 2: A composite material for automobile ceiling, which sequentially includes a bottom non-woven fabric, a lower film, a PP fiber / glass fiber mat, a barrier layer, an upper film and a fabric layer from bottom to top. The fabric layer is a spunlace non-woven fabric with a thickness of 2 mm, the bottom non-woven fabric is a spunbond non-woven fabric with a thickness of 2 mm, both the upper film and the lower film are PP films, the PP fiber / glass fiber mat is made from Preparation Example 1, the barrier layer includes sequentially laminated PP films, maleic anhydride modified PP films, PA films, maleic anhydride modified PP films and PP films, and the thickness of each PP film is 0.03 mm.

[0070] The preparation method of the above composite material for automobile ceiling includes the following steps:

[0071] Mix polypropylene resin and maleic anhydride grafted polypropylene evenly according to the mass percentages of 60% and 40%, heat up to melting and then extrude and pelletize. After hot melt calendaring at 230 °C, a maleic anhydride modified PP film with a thickness of 0.04 mm is obtained;

[0072] Laminated the PP film, maleic anhydride modified PP film, PA film, maleic anhydride modified PP film and PP film in sequence, and carry out die pressing and compounding to obtain a barrier layer with a thickness of 0.12 mm. The die pressing and compounding temperature is 160 °C and the time is 30 s;

[0073] Laminated the spunbond non-woven fabric, PP film, PP fiber / glass fiber mat, barrier layer and PP film in sequence, cooled and cut after hot pressing and forming, to obtain a PP glass fiber board with a thickness of 4.5 mm. The hot pressing and forming temperature is 150 °C and the time is 45 s.

[0074] Example 3: A composite material for automobile ceiling, which is different from Example 1 in that the PP fiber / glass fiber mat is made from Preparation Example 2.

[0075] Example 4: A composite material for automobile ceiling, which is different from Example 1 in that the PP fiber / glass fiber mat is made from Preparation Example 3.

[0076] Example 5: A composite material for automobile ceiling, which is different from Example 3 in that the PP fiber / glass fiber mat is made from Preparation Example 4.

[0077] Example 6: A composite material for automobile ceiling, which is different from Example 3 in that the PP fiber / glass fiber mat is made from Preparation Example 5.

[0078] Example 7: A composite material for automotive ceiling, which is different from that of Example 3 in that the PP fiber / glass fiber mat is made from Preparation Example 6.

[0079] Example 8: A composite material for automotive ceiling, which is different from that of Example 3 in that the upper adhesive film is a PP adhesive film, and the lower adhesive film is prepared by mixing polypropylene resin and sound absorption enhancer in a mass ratio of 1:0.2, melting and casting into a film at 180 °C, with a thickness of 0.04 mm, and the sound absorption enhancer is made from Preparation Example 7.

[0080] Example 9: A composite material for automotive ceiling, which is different from that of Example 3 in that the upper adhesive film is a PP adhesive film, and the lower adhesive film is prepared by mixing polypropylene resin and sound absorption enhancer in a mass ratio of 1:0.1, melting and casting into a film at 180 °C, with a thickness of 0.04 mm, and the sound absorption enhancer is made from Preparation Example 8.

[0081] Example 10: A composite material for automotive ceiling, which is different from that of Example 8 in that the sound absorption enhancer is made from Preparation Example 9.

[0082] Example 11: A composite material for automotive ceiling, which is different from that of Example 8 in that the sound absorption enhancer is made from Preparation Example 10.

[0083] Example 12: A composite material for automotive ceiling, which is different from that of Example 8 in that the sound absorption enhancer is diatomite, selected from Zhongshikeyuan Mineral Products in Lingshou County, with a model of 300.

[0084] Example 13: A composite material for automotive ceiling, which is different from that of Example 8 in that the upper adhesive film is made by the following method:

[0085] Mix 70 g of polypropylene resin, 28 g of EPDM particles and 4.2 g of nano-silica evenly, then heat up for melting, extrusion granulation and injection molding, hot press at 185 °C for 5 min to make a sheet with a thickness of 1 mm, then heat at 175 °C for 30 s, stretch to 0.04 mm at a speed of 480 mm / min, and then cool down to 140 °C at a rate of 15 °C / min, and keep heat treatment for 60 min to obtain a PP adhesive film. The extrusion granulation temperature: Zone 1 is 100 °C, Zone 2 is 120 °C, Zone 3 is 140 °C, Zone 4 is 180 °C, Zone 5 is 195 °C, Zone 6 is 195 °C, and the die head is 185 °C. The injection molding temperature: the temperature of Zone 1 is 200 °C, the temperature of Zone 2 is 195 °C, the temperature of Zone 3 is 175 °C, the pressure is 70 MPa, and the holding pressure time is 19 s.

[0086] Example 14: A composite material for automotive ceiling, which is different from that of Example 8 in that the upper adhesive film is made by the following method:

[0087] Mix 70 g of polypropylene resin, 21 g of EPDM particles and 2.8 g of nano-silica evenly, then heat up to melt and extrude into pellets, followed by injection molding. Hot press at 190 °C for 4 min to make a sheet with a thickness of 1 mm. Then heat at 180 °C for 20 s, stretch at a speed of 500 mm / min to 0.04 mm, and then cool down to 145 °C at a rate of 20 °C / min and keep the temperature for heat treatment for 50 min to obtain a PP adhesive film. The extrusion granulation temperature: zone 1 is 100 °C, zone 2 is 120 °C, zone 3 is 140 °C, zone 4 is 180 °C, zone 5 is 195 °C, zone 6 is 195 °C, and the die head is 185 °C. The injection molding temperature: the temperature of zone 1 is 200 °C, the temperature of zone 2 is 195 °C, the temperature of zone 3 is 175 °C, the pressure is 70 MPa, and the holding pressure time is 19 s.

[0088] Example 15: A composite material for automotive ceiling, which is different from Example 13 in that no nano-silica is added.

[0089] Example 16: A composite material for automotive ceiling, which is different from Example 13 in that no EPDM is added.

[0090] Example 17: A composite material for automotive ceiling, which is different from Example 13 in that after mixing polypropylene resin, EPDM particles and nano-silica and extruding into pellets, it is hot melt cast at 200 °C to make an upper adhesive film with a thickness of 0.04 mm.

[0091] Comparative Example

[0092] Comparative Example 1: A composite material for automotive ceiling, which is different from Example 1 in that no barrier layer is provided.

[0093] Comparative Example 2: A composite material for automotive ceiling, which is different from Example 1 in that maleic anhydride-modified PP films are not provided on both sides of the PA film, and the barrier layer only includes PP adhesive film, PA film and PP adhesive film laminated in sequence.

[0094] Comparative Example 3: A composite material for automotive ceiling, which is different from Example 1 in that the PA film in the barrier layer is replaced with a PP adhesive film, and the barrier layer is PP adhesive film, maleic anhydride-modified PP film, PP adhesive film, maleic anhydride-modified PP film and PP adhesive film laminated with each other.

[0095] Performance Detection Test

[0096] Prepare the composite material for automotive ceiling according to the methods in the examples and comparative examples, and detect its performance with reference to the following methods, and record the detection results in Table 1.

[0097] 1. Proportion of mottled area: Thermally press and bond the made fiberglass board with the non-woven fabric layer of the automotive ceiling, and observe the proportion of mottled areas on the same area.

[0098] 2. Flexural strength: Tested in accordance with GB / T 3356-2014 "Test Method for Flexural Properties of Oriented Fiber Reinforced Polymer Matrix Composites". Five points are taken for each sample for testing, and the results are averaged.

[0099] 3. Sound insulation quantity: Tested with reference to GB / T 18696.1-2004 "Measurement of Sound Absorption Coefficient and Acoustic Impedance in an Impedance Tube - Part 1: Standing Wave Ratio Method".

[0100] Table 1 Performance Testing of Composites for Automobile Roof Linings

[0101]

[0102] Combined with Examples 1-2, Comparative Example 1 and the test data in Table 1, it can be seen that after adding a barrier layer to the fiberglass board, it can effectively block the diffusion of antioxidants and other additives in the PP fiber / glass fiber mat, thereby reducing the occurrence of mottling in the automobile roof lining layer and improving the appearance quality of the automobile roof lining layer.

[0103] Compared with Example 1, Examples 3 and 4 use the PP fiber / glass fiber mats prepared by Preparation Example 2 and Preparation Example 3 respectively. As shown in Table 1, after the PP fiberglass board prepared in Examples 3-4 is compounded with the fabric layer, the mottled area changes little, but its sound absorption and insulation effects are significantly enhanced, and the flexural strength increases.

[0104] In Example 5, the PP fiber / glass fiber mat prepared by Preparation Example 4 is used. Compared with Example 3, the glass fiber is not impregnated with silica sol, and it can be seen that the sound absorption ability of the prepared PP fiberglass board is reduced and the sound insulation quantity is decreased.

[0105] Compared with Example 3, Example 6 uses the PP fiber / glass fiber mat prepared by Preparation Example 5, in which the glass fiber is not impregnated with silica sol and the anhydrous ethanol solution of graphene oxide is not impregnated. The sound insulation quantity of the PP fiberglass board prepared in Example 6 is significantly reduced, and the flexural strength also decreases, indicating that the pretreatment of glass fiber can effectively enhance the noise reduction, sound absorption and flexural resistance effects of the PP fiberglass board.

[0106] In Example 7, the PP fiber / glass fiber mat prepared by Preparation Example 6 is used. A suspension of commercially available polypropylene fiber is prepared and then poured on the matrix mat. Compared with Example 3, its sound insulation quantity is reduced and the flexural strength decreases, indicating that the polypropylene fiber prepared in this application has a certain sound insulation effect and stronger flexural resistance ability.

[0107] Compared with Example 3, in Examples 8 and 9, although the upper film is still a PP film, a fibrous sound-absorbing and strengthening agent is added to the lower film. The sound-absorbing and strengthening agent is made by mixing PET, EV, and calcium carbonate, spinning, and impregnating with hydrochloric acid, etc. It can be seen that the sound insulation amount of the PP fiberglass board made in Examples 8 and 9 is further increased, the noise reduction and sound absorption effects are enhanced, and the bending strength is increased.

[0108] In Example 10, the sound-absorbing and strengthening agent prepared in Preparation Example 9 is used. Compared with Preparation Example 7 in Example 8, it is not impregnated with hydrochloric acid solution. It can be seen that the bending strength of the made PP fiberglass board changes little, but the sound absorption effect decreases.

[0109] In Example 11, the sound-absorbing and strengthening agent prepared in Preparation Example 10 is used. Compared with Preparation Example 8, PBT resin is not added. It can be seen that the bending resistance of the fiberglass board decreases, and the sound absorption effect changes little.

[0110] In Example 12, diatomite is used as the sound-absorbing and strengthening agent. Compared with Example 9, the sound absorption effect decreases, and the bending resistance and anti-speckling ability change little. It can be seen that the noise reduction effect of the polypropylene film made by adding diatomite to polypropylene is inferior to the sound-absorbing and strengthening agent of this application.

[0111] Compared with Example 8, in Examples 13 and 14, the upper film is made by mixing polypropylene resin, EPDM, and nano-silica and then performing hot stretching, cooling, and annealing heat treatment, etc. It can be seen from the data in Table 1 that the speckle problem of the PP fiberglass board prepared in Examples 13-14 is further improved after hot pressing with the fabric layer, indicating that the bending resistance and anti-deformation ability of the upper film are increased, and the bending resistance of the fiberglass board is enhanced.

[0112] Compared with Example 13, in Examples 15 and 16, when preparing the upper PP film, nano-silica and EPDM particles are not added respectively. The data in Table 1 show that the bending resistance of the PP fiberglass board prepared in Examples 15-16 decreases compared with Example 13, the speckle area increases slightly, but the sound insulation amount changes little.

[0113] In Example 17, polypropylene resin is mixed with EPDM and nano-silica and then cast into a film without performing hot stretching and other treatments. It can be known from the data comparison in Table 1 that the bending strength of the PP fiberglass board prepared in Example 16 decreases compared with Example 13, and the speckle area increases.

[0114] In Comparative Example 2, maleic anhydride-modified PP film is not added, and in Comparative Example 3, PP film is used to replace PA film. The data in Table 1 show that compared with Example 1, the improvement of the fiberglass board prepared in Comparative Example 2 and Comparative Example 3 for the car roof speckle problem is not obvious.

[0115] 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 composite material for automobile ceiling, characterized in that: It comprises a bottom non-woven fabric, a lower adhesive film, a PP fiber / glass fiber mat, a barrier layer, an upper adhesive film and a fabric layer in sequence, wherein the barrier layer is formed by compression molding of a PP adhesive film, a maleic anhydride modified PP film, a PA film, a maleic anhydride modified PP film and a PP adhesive film in contact with each other in sequence; The method for preparing the maleic anhydride modified PP film is as follows: maleic anhydride grafted polypropylene and polypropylene resin are mixed, extruded into granules, and cast to prepare the maleic anhydride modified PP film; The PP fiber / glass fiber mat comprises PP fiber and glass fiber in a mass ratio of 1:1; The preparation method of the PP fiber / glass fiber mat is as follows: The glass fiber is immersed in silica sol, taken out and immersed in an anhydrous ethanol solution of graphene oxide, ultrasonicated at a power of 250-300W for 100-120min, then dried at 50-55°C under normal pressure, and needled to obtain a matrix felt; The polypropylene and cellulose acetate butyrate are mixed in a mass ratio of 1:0.1-0.2, and the mixture is melt-spun after vacuum drying. The spun product is extracted at 60-65° C. for 20-24 hours using acetone as a solvent to obtain PP fiber. The PP fiber is dispersed in the polyacrylamide solution to obtain a suspension, and the suspension is poured on a base felt, vacuum filtered and dried to obtain a PP fiber / glass fiber felt.

2. The composite material for automobile ceiling according to claim 1, characterized in that: The thickness of the barrier layer is 0.12-0.15 mm.

3. The composite material for automobile ceiling according to claim 1, characterized in that: The lower layer of adhesive film comprises polypropylene resin and sound absorption enhancer in a mass ratio of 1:0.1-0.

2.

4. The composite material for automobile ceiling according to claim 3, characterized in that: The preparation method of the sound absorption enhancer is as follows: PET chips are mixed with PBT resin and calcium carbonate, melted and spun to obtain PET fibers, which are then immersed in a 5.5-6wt% hydrochloric acid solution for 20-24 hours, filtered, washed and dried to obtain a sound absorption enhancer. The mass ratio of PET chips, PBT resin and calcium carbonate is 1:0.1-0.15:0.03-0.

05.

5. The composite material for automobile ceiling according to claim 1, characterized in that: The preparation method of the upper layer film is as follows: The polypropylene resin, EPDM particles and nano-silicon dioxide are uniformly mixed in a mass ratio of 1:0.3-0.4:0.04-0.06, and then extruded into granules and injection molded. After hot pressing at 185-190°C for 4-5 minutes and heating at 175-180°C for 20-30 seconds, the mixture is stretched to 0.03-0.04 mm at a speed of 480-500 mm / min, and then cooled to 140-145°C at a speed of 15-20°C / min, and heat-treated at a heat preservation rate of 50-60 minutes.

6. The composite material for automobile ceiling according to claim 1, characterized in that: The bottom nonwoven fabric is one of spunlace nonwoven fabric, spunbond nonwoven fabric or hot-rolled nonwoven fabric.

7. The method for preparing the composite material for automobile ceiling according to any one of claims 1 to 6, characterized in that: The following steps are involved: The maleic anhydride grafted polypropylene and polypropylene resin are mixed, extruded into granules, and cast to prepare a maleic anhydride modified PP film; The PP film, the maleic anhydride modified PP film, the PA film, the maleic anhydride modified PP film and the PP film are sequentially laminated and molded to form a barrier layer; The bottom non-woven fabric, the lower adhesive film, the PP fiber / glass fiber felt, the barrier layer, the upper adhesive film and the fabric layer are sequentially laminated, hot-pressed, cooled and cut to obtain the PP glass fiber board.

8. The method for preparing the composite material for automobile ceiling according to claim 7, characterized in that: The temperature of the compression molding is 160-170°C and the time is 30-40s; The temperature of the hot pressing molding is 150-160° C. and the time is 35-45 seconds.

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