Automotive interior ceiling and preparation method thereof

Abstract

The invention relates to an automobile interior ceiling and a preparation method thereof, and relates to the technical field of automobile ceiling production. An automotive interior ceiling comprises a base material and a fabric, and a preparation method of the base material comprises the following steps: obtaining a composite fiber web of modified bamboo fibers and modified polypropylene fibers through electrostatic spinning and air laying processes; carrying out microwave curing treatment on the composite fiber net to obtain a fiber skeleton; putting the fiber skeleton into a microsphere suspension of expanded microspheres, completely immersing for a period of time, passing through an infrared heating area at a certain speed, and then carrying out plasma treatment to obtain a base material; wherein the modified bamboo fibers are obtained by modifying bamboo fibers with hemicellulase, and the modified polypropylene fibers are obtained by grafting polypropylene fibers with maleic anhydride. The preparation process does not involve the use of liquid glue, so that the odor and weight of the automotive interior ceiling are remarkably reduced, the process environment is cleaner and more sanitary, and the preparation method is a sustainable green production process.

Description

Technical Field

[0001] The present application relates to the technical field of automobile roof production, and in particular to an automobile interior ceiling and a preparation method thereof. Background Art

[0002] The car roof is a decorative covering installed on the top of the car. It is an important component of the car that combines decorative and functional features. It can effectively reduce the outside noise entering the car, while blocking heat from entering the car in summer and reducing heat loss in the car in winter, thereby maintaining a comfortable temperature in the car.

[0003] Currently, the vast majority of car roofs on the market mainly use PU structure, and 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. Summary of the Invention

[0004] In order to improve the problem that the PU structure of the car roof will produce volatile organic compounds such as formaldehyde and benzene due to the reliance on liquid glue in the production process, resulting in odor in the car, the present application provides a car interior ceiling and a preparation method thereof.

[0005] In a first aspect, the present application provides an automobile interior ceiling, which adopts the following technical solution: An automobile interior ceiling comprises a substrate and a fabric, wherein the preparation method of the substrate comprises the following steps: (1) Modified bamboo fiber and modified polypropylene fiber were mixed in a mass ratio of 7:3 to obtain mixed fiber, and part of the mixed fiber was added into a mixed solvent of dichloromethane and acetone to obtain a spinning solution; (2) The spinning solution was electrospun to form a fiber bundle in the vertical direction and deposited for 5 minutes. Then, the mixed fiber was evenly spread and deposited in the horizontal direction for 3 minutes by airflow. The deposition was repeated 5 times to obtain a composite fiber web. (3) subjecting the composite fiber web to microwave curing for 30-60 seconds to obtain a fiber skeleton; (4) Add the heat-expandable microspheres into water and evenly disperse them to form a microsphere suspension. Then, slowly place the fiber skeleton into the microsphere suspension and completely immerse it for a period of time to obtain a microsphere-loaded fiber skeleton. (5) Passing the microsphere-loaded fiber skeleton through an infrared heating zone at a speed of 0.1-0.2 m / min, and then performing plasma treatment to obtain a substrate; The modified bamboo fiber is obtained by modifying bamboo fiber with hemicellulase, and the modified polypropylene fiber is obtained by grafting maleic anhydride onto polypropylene fiber.

[0006] By adopting these technical solutions, the modified bamboo fiber, after being treated with hemicellulase, increases the number of surface active groups such as hydroxyl groups. Polar groups such as carboxyl anhydride are introduced into the modified polypropylene fiber through maleic anhydride grafting, significantly improving the compatibility between the modified bamboo fiber and modified polypropylene fiber. Furthermore, microwave curing utilizes thermal effects to promote molecular-level bonding between fibers, while infrared heating and plasma treatment further strengthen the bonding between fibers and microspheres, and between fibers themselves. The entire process eliminates the need for glue, thereby eliminating the release of VOCs caused by glue and significantly reducing odor in the vehicle.

[0007] In the composite fiber web of the present application, the vertical mixed fiber bundles provide longitudinal strength support, so that the substrate is not easily broken when subjected to longitudinal external force; the horizontally spread mixed fibers ensure that the substrate has good toughness and uniformity in the transverse direction, forming a criss-cross three-dimensional fiber structure, which can effectively improve the overall mechanical properties of the substrate.

[0008] The heat-expandable microspheres are attached to the fiber skeleton, and the density of the substrate is controlled by the temperature and time of infrared heating, forming a tiny cavity structure inside the substrate, thereby enhancing the thermal insulation and sound insulation performance of the car roof. At the same time, the heat-expandable microspheres can also be combined with the mechanical properties of the fiber skeleton to effectively absorb energy and provide a certain degree of cushioning when impacted by external forces.

[0009] Continuous plasma treatment of the fiber surface can generate oxygen-containing polar groups, effectively improving the interfacial shear strength between the modified bamboo fiber and the modified polypropylene fiber, and further improving the mechanical properties of the substrate.

[0010] Preferably, the preparation method of the modified bamboo fiber comprises the following steps: S1. Immersing bamboo fiber in a buffer solution containing hemicellulase and simultaneously applying ultrasound to obtain enzymatically hydrolyzed fiber; S2. The enzymatic fiber is sequentially passed through the first temperature zone, the second temperature zone and the third temperature zone, and stays in each temperature zone for a period of time to obtain the initial modified bamboo fiber; S3. The initial modified bamboo fiber was sequentially acid-washed, washed, and dried to obtain modified bamboo fiber; The temperature of the first temperature zone is 50°C, the temperature of the second temperature zone is 75°C, and the temperature of the third temperature zone is 110°C.

[0011] By adopting the above technical solution, ultrasound accelerates the contact and reaction between enzymes and bamboo fibers, improving the efficiency of enzymatic hydrolysis and making it more complete and uniform. A gradient temperature treatment achieves structural reconstruction through "drying-disentanglement-crystallization": the first temperature zone removes free water from the enzymatically hydrolyzed fibers through low-temperature drying, preventing moisture from causing fiber expansion or thermal damage during high-temperature treatment; the second temperature zone further disentangles the molecular chains remaining after enzymatic hydrolysis, improving the flexibility of the bamboo fibers; and the third temperature zone prompts the disordered cellulose chains to rearrange after enzymatic hydrolysis, forming a more regular crystalline structure.

[0012] Preferably, the power of the ultrasonic wave in S1 is 120-150w.

[0013] By adopting the above technical solution, when the power of the ultrasound is too low, the enzymatic hydrolysis efficiency is relatively low, and hemicellulose residues exist; when the power of the ultrasound is too high, the bamboo fiber may be excessively damaged, resulting in a decrease in the performance of the modified bamboo fiber; for this reason, the applicant finally determined after a lot of research and experimental verification that the power of the ultrasound in this application is appropriate to be above.

[0014] Preferably, the enzymatically hydrolyzed fiber in S2 stays in each temperature zone for 8-12 minutes.

[0015] By adopting the above technical solution, the above residence time range can ensure the sufficient physical and chemical changes such as drying, untangling, and crystallization in each temperature zone, while avoiding the performance degradation of bamboo fiber due to excessive treatment; the total treatment time of the three temperature zones not only meets the thermodynamic requirements of fiber structure reconstruction, but also avoids the reduction of production line efficiency due to excessive time.

[0016] Preferably, when the enzymatically decomposed fibers in S2 stay in the third temperature zone, nano-silica aerogel is sprayed on the enzymatically decomposed fibers, and after the fibers stay in the third temperature zone for a period of time, initial modified bamboo fibers are obtained.

[0017] By adopting the above technical solution, in the third temperature zone, the cellulose chains of bamboo fiber are in a dynamic rearrangement process, and the nano-silica aerogel particles can serve as "crystallization induction points" to promote the orderly arrangement of cellulose molecular chains and improve the crystallinity, thereby enhancing the axial tensile strength and rigidity of bamboo fiber.

[0018] At the same time, the silanol groups on the surface of nano-silica aerogel can form hydrogen bonds with the hydroxyl groups on the surface of bamboo fiber. At high temperatures, some of the silanol groups may also dehydrate and condense to form -Si-OC- covalent bonds, significantly enhancing the interfacial bonding between the aerogel and bamboo fiber.

[0019] Nano-silica aerogel is also an excellent thermal insulation material. Its nanopores can hinder heat conduction. At the same time, its porous structure has a scattering and absorption effect on sound waves, which can synergize with the cavity structure of thermally expandable microspheres to improve the thermal and sound insulation properties of the substrate.

[0020] Preferably, the heat-expandable microspheres are one of methyl methacrylate copolymer microspheres and core-shell hydrocarbon microspheres.

[0021] By adopting the above technical solution, both methyl methacrylate copolymer microspheres and core-shell hydrocarbon microspheres have good thermal expansion properties. The thermal expansion temperature range of the two is adapted to the heating conditions during the substrate preparation process, and they can expand at a suitable temperature to form a stable cavity structure.

[0022] Preferably, the heat-expandable microspheres are methyl methacrylate copolymer microspheres.

[0023] Preferably, the initial particle size of the methyl methacrylate copolymer microspheres is 20-40 μm.

[0024] By adopting the above technical solution, methyl methacrylate copolymer microspheres are designed through the copolymerization of methyl methacrylate and other monomers to form a dense cross-linked structure, which can effectively resist hydrolysis and degradation in high temperature and high humidity environments. Its hydrophobic polymer chain segments can reduce moisture penetration, thereby maintaining stable physical properties, having excellent moisture and heat resistance, and can continuously maintain a heat-insulating and sound-insulating cavity structure.

[0025] At the same time, the shell of the methyl methacrylate copolymer microspheres contains ester groups, while the surface of the nano-silica aerogel added to the modified bamboo fiber is rich in silanol groups. The two can form hydrogen bond interactions, further enhancing the overall compatibility between the three-dimensional fiber network and the microspheres.

[0026] The methyl methacrylate copolymer microspheres with an initial particle size of 20-40 μm are well matched with the pore size of the composite fiber mesh, which can form a cavity large enough to hinder heat conduction and sound wave propagation, while not causing the fiber skeleton to be deformed due to excessive expansion.

[0027] Preferably, the preparation method of the modified polypropylene fiber comprises the following steps: blending polypropylene particles with maleic anhydride and an initiator, melt grafting at 180-200° C., and pulling and cooling to obtain the modified polypropylene fiber.

[0028] By adopting the above technical solution, the modified polypropylene fiber obtained by grafting maleic anhydride onto polypropylene fiber can effectively improve the compatibility between the modified polypropylene fiber and the modified bamboo fiber, thereby significantly improving the structural stability of the three-dimensional fiber structure.

[0029] In a second aspect, the present application provides a method for preparing the aforementioned automobile interior ceiling, which adopts the following technical solution: A method for preparing the above-mentioned automobile interior ceiling is used to prepare the above-mentioned automobile interior ceiling, comprising the following steps: 1) The substrate is heated to a surface temperature of 160-170°C. The robot places 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 positioned below the fabric. The upper mold automatically falls, and pressure is maintained to form the roof prototype. 2) The ceiling prototype is placed in a punching die and positioned using the shape of the skylight opening. The punching press maintains a holding pressure of 200-220 bar for 5-7 seconds. The punching die is equipped with a floating platen and a cold die and cold knife. The cold die and cold knife punch out excess side holes to obtain the ceiling base. 3) The skylight opening substrate and fabric of the roof base are integrally rolled and covered to obtain the automobile interior ceiling.

[0030] In summary, this application has the following beneficial effects: 1. This application uses vertically blended fiber bundles to provide longitudinal strength support, and horizontally blended fibers (modified bamboo fiber and modified polypropylene fiber) to form a uniform toughness structure, constructing a crisscrossing three-dimensional fiber skeleton. This significantly improves the substrate's fracture resistance and overall structural stability, meeting the mechanical strength requirements of automotive interiors. 2. This application uses thermally expandable microspheres to form a tiny cavity structure after infrared heating. Combined with the porous characteristics of nano-silica aerogel, it synergistically hinders heat conduction and sound wave propagation, effectively improving the sound insulation and heat insulation performance of the car interior ceiling; 3. This application achieves crystal structure reconstruction through gradient temperature treatment of modified bamboo fiber, using nano-silica aerogel as a crystallization induction point to enhance the rigidity of the substrate. Furthermore, by matching the particle size of thermally expandable microspheres with the pores of the fiber mesh, the cavity structure is maintained in a long-term stable state. 4. The preparation process of this application does not involve the use of liquid glue, which significantly reduces the odor and weight of the car interior ceiling, and the process environment is cleaner and more hygienic, which is a green production process with sustainable development. DETAILED DESCRIPTION

[0031] The raw materials in this application (all commercially available products unless otherwise specified) include the following: Hemicellulase: enzyme activity is 1U / mg; Bamboo fiber: diameter 15±3mm, linear density 25±3tex; Polypropylene granules: commercially available product with CAS number 9003-07-0; Maleic anhydride: a commercially available product with CAS number 108-31-6; Nano-silica aerogel: hydrophobic; Methyl methacrylate copolymer microspheres: Matsumoto Japan F-30D (initial particle size 10-18 μm), F-230D (initial particle size 20-35 μm); Core-shell structured hydrocarbon microspheres: Kureha Microsphere®; Initiator: A commercially available product of dicumyl peroxide was used.

[0032] Modified bamboo fiber: Preparation Example 1 The preparation method of modified bamboo fiber comprises the following steps: S1. Dissolve hemicellulase in water and adjust the solution pH to 5.5 to obtain a hemicellulase-containing buffer solution; immerse bamboo fiber in the hemicellulase-containing buffer solution and simultaneously apply 40kHz ultrasonic waves (power 130W, pulse mode) to obtain enzymatically hydrolyzed fiber; S2. The enzymatically hydrolyzed fibers were placed on a mobile conveyor belt and sequentially passed through the first temperature zone (50°C), the second temperature zone (75°C), and the third temperature zone (110°C), with a stay of 10 minutes in each temperature zone to obtain the initial modified bamboo fiber; S3. The initial modified bamboo fiber is sequentially acid-washed (with an oxalic acid solution having a mass concentration of 5 wt %), washed with water, and dried (at 60° C.) to obtain modified bamboo fiber.

[0033] Preparation Example 2 The preparation method of the modified bamboo fiber is different from that of Preparation Example 1 in that the power of the ultrasonic wave in S1 is 100W.

[0034] Preparation Example 3 The preparation method of the modified bamboo fiber is different from that of Preparation Example 1 in that the power of the ultrasonic wave in S1 is 120W.

[0035] Preparation Example 4 The preparation method of the modified bamboo fiber is different from that of Preparation Example 1 in that the power of the ultrasonic wave in S1 is 150W.

[0036] Preparation Example 5 The preparation method of the modified bamboo fiber is different from that of Preparation Example 1 in that the power of the ultrasonic wave in S1 is 180W.

[0037] Preparation Example 6 The preparation method of the modified bamboo fiber is different from that of Preparation Example 1 in that the enzymatically hydrolyzed fiber in S2 stays in each temperature zone for 5 minutes.

[0038] Preparation Example 7 The preparation method of the modified bamboo fiber is different from that of Preparation Example 1 in that the enzymatically hydrolyzed fiber in S2 stays in each temperature zone for 8 minutes.

[0039] Preparation Example 8 The preparation method of the modified bamboo fiber is different from that of Preparation Example 1 in that the enzymatically hydrolyzed fiber in S2 stays in each temperature zone for 12 minutes.

[0040] Preparation Example 9 The preparation method of the modified bamboo fiber is different from that of Preparation Example 1 in that the enzymatically hydrolyzed fiber in S2 stays in each temperature zone for 15 minutes.

[0041] Preparation Example 10 The preparation method of modified bamboo fiber is different from that of Preparation Example 1 in that, in S2, the enzymatically hydrolyzed fiber is placed on a mobile conveyor belt and passes through the first temperature zone (50°C) and the second temperature zone (75°C) in sequence, and stays in each temperature zone for 10 minutes; when the enzymatically hydrolyzed fiber enters the third temperature zone, nano-silica aerogel is sprayed on the enzymatically hydrolyzed fiber, and after staying in the third temperature zone for 10 minutes, the initial modified bamboo fiber is obtained.

[0042] Modified polypropylene fiber: Preparation Example 11 The preparation method of modified polypropylene fiber comprises the following steps: Polypropylene fiber is blended with maleic anhydride and dicumyl peroxide in a mass ratio of 10:2.5:0.35, placed in a screw extruder at 200°C (180-200°C) for melt grafting for 20 minutes, and then pulled and cooled to obtain modified polypropylene fiber.

[0043] Base material: Preparation Example 12 The method for preparing a substrate comprises the following steps: (1) The modified bamboo fiber obtained in Preparation Example 1 and the modified polypropylene fiber obtained in Preparation Example 11 were mixed in a mass ratio of 7:3 to obtain a mixed fiber, and a portion of the mixed fiber was added to a mixed solvent of dichloromethane and acetone (the mass ratio of dichloromethane to acetone was 7:3) to obtain a spinning solution; (2) The spinning solution was electrospun (spinning voltage was set to 25 kV, receiving distance was set to 15 cm, and solution propulsion speed was set to 1.0 mL / h) to form a fiber bundle in the vertical direction. After deposition for 5 minutes, the mixed fiber was laid through an air-laid machine, evenly spread and deposited in the horizontal direction for 3 minutes, and then electrospun again. The deposition was repeated 5 times to obtain a composite fiber web. (3) The composite fiber web is subjected to microwave curing treatment, with the microwave frequency set to 2.45 GHz and the power to 800 W, and the treatment time is 60 s (30-60 s is acceptable) to obtain a fiber skeleton; (4) Methyl methacrylate copolymer microspheres (F-230D) were added to water and uniformly dispersed to form a microsphere suspension. The mass fraction of methyl methacrylate copolymer microspheres in the microsphere suspension was 10%. The fiber skeleton was then slowly placed into the microsphere suspension and completely immersed for 30 minutes to obtain a microsphere-loaded fiber skeleton. (5) The microsphere-loaded fiber skeleton is passed through an infrared heating zone at a speed of 0.1 m / min (0.1-0.2 m / min is acceptable). The temperature of the infrared heating zone is 100°C, and then plasma treatment is performed using an atmospheric pressure helium plasma treatment system with a power of 300 W, a helium flow rate of 10 L / min, and a treatment speed of 0.5 m / min.

[0044] Preparation Example 13 The method for preparing the substrate is different from that of Preparation Example 12 in that, in step (1), unmodified bamboo fiber and unmodified polypropylene fiber are mixed in a mass ratio of 7:3 to obtain mixed fiber.

[0045] Preparation Example 14 The method for preparing the substrate is different from that of Preparation Example 12 in that step (4) is not performed, and the fiber skeleton is directly passed through the infrared heating zone at a speed of 0.1 m / min.

[0046] Preparation Example 15 The method for preparing the substrate is different from that of Preparation Example 12 in that in step (5), the microsphere-loaded fiber skeleton is passed through an infrared heating zone at a speed of 0.1 m / min to obtain the substrate without plasma treatment.

[0047] Preparation Example 16 The method for preparing the substrate is different from that of Preparation Example 12 in that, in step (1), the modified bamboo fiber obtained in Preparation Example 2 and the modified polypropylene fiber obtained in Preparation Example 12 are mixed in a mass ratio of 7:3 to obtain a mixed fiber.

[0048] Preparation Example 17 The method for preparing the substrate is different from that of Preparation Example 12 in that, in step (1), the modified bamboo fiber obtained in Preparation Example 3 and the modified polypropylene fiber obtained in Preparation Example 11 are mixed in a mass ratio of 7:3 to obtain a mixed fiber.

[0049] Preparation Example 18 The method for preparing the substrate is different from that of Preparation Example 12 in that, in step (1), the modified bamboo fiber obtained in Preparation Example 4 and the modified polypropylene fiber obtained in Preparation Example 11 are mixed in a mass ratio of 7:3 to obtain a mixed fiber.

[0050] Preparation Example 19 The method for preparing the substrate is different from that of Preparation Example 12 in that, in step (1), the modified bamboo fiber obtained in Preparation Example 5 and the modified polypropylene fiber obtained in Preparation Example 11 are mixed in a mass ratio of 7:3 to obtain a mixed fiber.

[0051] Preparation Example 20 The method for preparing the substrate is different from that of Preparation Example 12 in that, in step (1), the modified bamboo fiber obtained in Preparation Example 6 and the modified polypropylene fiber obtained in Preparation Example 11 are mixed in a mass ratio of 7:3 to obtain a mixed fiber.

[0052] Preparation Example 21 The method for preparing the substrate is different from that of Preparation Example 12 in that, in step (1), the modified bamboo fiber obtained in Preparation Example 7 and the modified polypropylene fiber obtained in Preparation Example 11 are mixed in a mass ratio of 7:3 to obtain a mixed fiber.

[0053] Preparation Example 22 The method for preparing the substrate is different from that of Preparation Example 12 in that, in step (1), the modified bamboo fiber obtained in Preparation Example 8 and the modified polypropylene fiber obtained in Preparation Example 11 are mixed in a mass ratio of 7:3 to obtain a mixed fiber.

[0054] Preparation Example 23 The method for preparing the substrate is different from that of Preparation Example 12 in that, in step (1), the modified bamboo fiber obtained in Preparation Example 9 and the modified polypropylene fiber obtained in Preparation Example 11 are mixed in a mass ratio of 7:3 to obtain a mixed fiber.

[0055] Preparation Example 24 The method for preparing the substrate is different from that of Preparation Example 12 in that, in step (1), the modified bamboo fiber obtained in Preparation Example 10 and the modified polypropylene fiber obtained in Preparation Example 11 are mixed in a mass ratio of 7:3 to obtain a mixed fiber.

[0056] Preparation Example 25 The preparation method of the substrate is different from that of Preparation Example 12 in that, in step (4), core-shell hydrocarbon microspheres are added to water and uniformly dispersed to form a microsphere suspension, wherein the mass fraction of methyl methacrylate copolymer microspheres in the microsphere suspension is 10%, and then the fiber skeleton is slowly placed into the microsphere suspension and completely immersed for 30 minutes to obtain a microsphere-loaded fiber skeleton.

[0057] Preparation Example 26 The preparation method of the substrate is different from that of Preparation Example 12 in that, in step (4), methyl methacrylate copolymer microspheres (F-30D) are added to water and uniformly dispersed to form a microsphere suspension, wherein the mass fraction of methyl methacrylate copolymer microspheres in the microsphere suspension is 10%, and then the fiber skeleton is slowly placed into the microsphere suspension and completely immersed for 30 minutes to obtain a microsphere-loaded fiber skeleton.

[0058] The present application is further described in detail below with reference to the following examples and comparative examples.

[0059] Example 1 A method for preparing an automobile interior ceiling comprises the following steps: 1) The substrate prepared in Preparation Example 12 was heated to a surface temperature of 170°C (160-170°C is acceptable). The robot placed the skylight reinforcement frame into the corresponding recess of the lower mold in the X direction. The fabric was automatically transferred to the center of the upper and lower molds in the Y direction. The heated substrate was automatically transferred to the center of the upper and lower molds in the -Y direction and positioned below the fabric. The upper mold automatically dropped, and molding was performed at 20°C and 40 bar molding pressure for 33 seconds to obtain a preliminary roof mold. 2) Place the ceiling prototype into the punching die and position it using the shape of the skylight opening. The punching press maintains a holding pressure of 210 bar (200-220 bar is acceptable) and a holding time of 7 seconds (5-7 seconds is acceptable). The punching die is equipped with a floating platen and a cold die and cold knife. The cold die and cold knife punch out the excess side holes to obtain the ceiling prototype. 3) The skylight base material and fabric of the roof base are integrally rolled and wrapped to obtain the automobile interior ceiling.

[0060] Comparative Examples 1-3 Comparative Example 1: Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 13, and the other conditions remained unchanged.

[0061] Comparative Example 2: Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 14, and the other conditions remained unchanged.

[0062] Comparative Example 3: Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 15, and the other conditions remained unchanged.

[0063] Table 1 Performance test table of Example 1 and Comparative Examples 1-3

[0064] The automobile interior ceilings of Example 1 and Comparative Examples 1-3 were subjected to the following performance tests. The test results are shown in Table 1: Performance testing (1) Odor test Refer to the standards and regulations of PV3900 to test the odor level of the car interior ceiling.

[0065] (2) Mechanical properties Use an electronic universal testing machine and refer to SMTC 5330 007-2019 to test the bending strength of the interior ceiling and record the data.

[0066] (3) Sound insulation performance The sound pressure level method is used to test the sound insulation performance of the ceiling. Sound pressure level test instruments are placed on both sides of the car interior ceiling. A sound signal is generated on the source side and transmitted to the receiving side through the ceiling. The sound pressure levels on both sides are recorded, and the sound pressure level difference is calculated to obtain the sound absorption coefficient.

[0067] Referring to Table 1, by comparing Example 1 with Comparative Examples 1-3, it can be seen that Example 1 and Comparative Examples 1-3 have less odor. This is because the present application adopts microwave curing treatment to promote molecular-level bonding between fibers, and infrared heating and plasma treatment further strengthen the bonding between fibers and microspheres, and between fibers. The entire process does not require glue, which greatly reduces the odor in the car.

[0068] The mechanical properties of the automobile interior ceiling of Example 1 are better than those of Comparative Example 1. This is because the bamboo fiber and polypropylene fiber in Comparative Example 1 are not modified, while the modified bamboo fiber and modified polypropylene fiber in Example 1 have better compatibility, resulting in a more stable structure.

[0069] The sound insulation performance of the automobile interior ceiling of Example 1 is better than that of Comparative Example 2. This is because the fiber skeleton in Comparative Example 2 is not loaded with methyl methacrylate copolymer microspheres, while the methyl methacrylate copolymer microspheres in Example 1 are attached to the fiber skeleton and form a tiny cavity structure inside the substrate through infrared heating, which can significantly improve the sound insulation performance of the substrate.

[0070] The mechanical properties of the automobile interior ceiling of Example 1 are better than those of Comparative Example 3. This is because Comparative Example 3 does not undergo plasma treatment, while the plasma in Example 1 continuously treats the fiber surface to generate oxygen-containing polar groups, effectively improving the interfacial shear strength between the modified bamboo fiber and the modified polypropylene fiber, and improving the mechanical properties of the substrate.

[0071] Examples 2-5 Example 2 Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 16, and the other conditions remained unchanged.

[0072] Example 3 Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 17, and the other conditions remained unchanged.

[0073] Example 4 Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 18, and the other conditions remained unchanged.

[0074] Example 5 Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 19, and the other conditions remained unchanged.

[0075] The automobile interior ceilings of Examples 2-5 were subjected to the above performance tests, and the test results are shown in Table 2.

[0076] Table 2 Performance test table of Examples 1-5

[0077] Referring to Table 2, it can be seen from comparative examples 1-5 that when the ultrasonic power is too low or too low, the mechanical properties of the automobile interior ceiling will be reduced. This is because when the ultrasonic power is too low, the enzymatic hydrolysis efficiency is relatively low, and hemicellulose residues are present. The residual hemicellulose may be partially degraded (such as glycosidic bond breakage) due to insufficient heat resistance during subsequent processing, resulting in the destruction of the structural integrity of the fiber skeleton; when the ultrasonic power is too high, the bamboo fiber may be excessively damaged, resulting in a decrease in the comprehensive performance of the modified bamboo fiber.

[0078] Examples 6-9 Example 6 Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 20, and the other conditions remained unchanged.

[0079] Example 7 Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 21, and the other conditions remained unchanged.

[0080] Example 8 Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 22, and the other conditions remained unchanged.

[0081] Example 9 Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 23, and the other conditions remained unchanged.

[0082] The automobile interior ceilings of Examples 6-9 were subjected to the above performance tests, and the test results are shown in Table 3.

[0083] Table 3 Performance test table of Example 1 and Examples 6-9

[0084] Referring to Table 3, by comparing Example 1 with Examples 6-9, it can be seen that if the enzymatically hydrolyzed fiber stays in each temperature zone for too short or too long, the mechanical properties of the automobile interior ceiling will be reduced. This is because if the residence time is too short, the physical and chemical changes of the enzymatically hydrolyzed fiber, such as drying, untangling, and crystallization, will not be sufficiently carried out, and the crystallinity will be too low, thereby reducing the support of the modified bamboo fiber; if the residence time is too long, the performance of the bamboo fiber will be degraded due to excessive treatment.

[0085] Example 10 Example 10 Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 24, and the other conditions remained unchanged.

[0086] The automobile interior ceiling of Example 10 was subjected to the above performance test, and the test results are shown in Table 4.

[0087] Table 4 Performance test table of Example 1 and Example 10

[0088] Referring to Table 4, by comparing Example 1 and Example 10, it can be seen that the mechanical properties and sound insulation properties of the automobile interior ceiling of Example 10 are better than those of Example 1. This is because in the third temperature zone, the nano-silica aerogel particles can serve as "crystallization induction points", thereby improving the crystallinity of the modified bamboo fiber and enhancing the mechanical properties of the bamboo fiber.

[0089] At the same time, the nanopores of nano-silica aerogel have scattering and absorption effects on sound waves, and can synergistically improve the sound insulation performance of the substrate with the cavity structure of methyl methacrylate copolymer microspheres.

[0090] Example 11 Example 11 Based on the preparation method of Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 25, and the other conditions remained unchanged.

[0091] The automobile interior ceiling of Example 11 was subjected to the above performance test, and the test results are shown in Table 4.

[0092] Table 5 Performance test table of Example 1 and Example 11

[0093] Referring to Table 5, by comparing Example 1 and Example 11, it can be seen that both the methyl methacrylate copolymer microspheres and the core-shell hydrocarbon microspheres can effectively maintain the sound insulation performance of the automobile interior ceiling. This is because both the methyl methacrylate copolymer microspheres and the core-shell hydrocarbon microspheres have good thermal expansion properties. The thermal expansion temperature range of the two is compatible with the heating conditions in the substrate preparation process, and they can expand at a suitable temperature to form a stable cavity structure.

[0094] The automobile interior ceiling sound insulation performance of Example 1 is better than that of Example 11, so methyl methacrylate copolymer microspheres are preferred.

[0095] Example 12 Example 12 Based on Example 1, the substrate prepared in Preparation Example 12 was replaced with the substrate prepared in Preparation Example 26, and the other conditions remained unchanged.

[0096] The automobile interior ceiling of Example 12 was subjected to the above performance test, and the test results are shown in Table 4.

[0097] Table 6 Performance test table of Example 1 and Example 12

[0098] Referring to Table 6, by comparing Example 1 and Example 12, it can be seen that if the initial particle size of the methyl methacrylate copolymer microspheres is too small, the sound insulation performance of the automobile interior ceiling will be reduced. This is because if the initial particle size is too small, it is difficult to form a cavity large enough to hinder the propagation of sound waves.

[0099] 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 non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An automobile interior ceiling, comprising a substrate and a fabric, characterized in that: The preparation method of the substrate comprises the following steps: (1) Modified bamboo fiber and modified polypropylene fiber were mixed in a mass ratio of 7:3 to obtain mixed fiber, and part of the mixed fiber was added into a mixed solvent of dichloromethane and acetone to obtain a spinning solution; (2) The spinning solution was electrospun to form a fiber bundle in the vertical direction and deposited for 5 minutes. Then, the mixed fiber was evenly spread and deposited in the horizontal direction for 3 minutes by airflow. The deposition was repeated 5 times to obtain a composite fiber web. (3) subjecting the composite fiber web to microwave curing for 30-60 seconds to obtain a fiber skeleton; (4) Add the heat-expandable microspheres into water and evenly disperse them to form a microsphere suspension. Then, slowly place the fiber skeleton into the microsphere suspension and completely immerse it for a period of time to obtain a microsphere-loaded fiber skeleton. (5) Passing the microsphere-loaded fiber skeleton through an infrared heating zone at a speed of 0.1-0.2 m / min, and then performing plasma treatment to obtain a substrate; The modified bamboo fiber is obtained by modifying bamboo fiber with hemicellulase, and the modified polypropylene fiber is obtained by grafting maleic anhydride onto polypropylene fiber.

2. The automobile interior ceiling according to claim 1, characterized in that: The preparation method of the modified bamboo fiber comprises the following steps: S1. Immersing bamboo fiber in a buffer solution containing hemicellulase and simultaneously applying ultrasound to obtain enzymatically hydrolyzed fiber; S2. The enzymatic fiber is sequentially passed through the first temperature zone, the second temperature zone and the third temperature zone, and stays in each temperature zone for a period of time to obtain the initial modified bamboo fiber; S3. The initial modified bamboo fiber was sequentially acid-washed, washed, and dried to obtain modified bamboo fiber; The temperature of the first temperature zone is 50°C, the temperature of the second temperature zone is 75°C, and the temperature of the third temperature zone is 110°C.

3. The automobile interior ceiling according to claim 2, characterized in that: The power of the ultrasonic wave in S1 is 120-150w.

4. The automobile interior ceiling according to claim 2, characterized in that: In S2, the enzymatically hydrolyzed fiber stays in each temperature zone for 8-12 minutes.

5. The automobile interior ceiling according to claim 2, characterized in that: When the enzymatically hydrolyzed fibers in S2 stay in the third temperature zone, nano-silica aerogel is sprayed on the enzymatically hydrolyzed fibers, and after they stay in the third temperature zone for a period of time, initial modified bamboo fibers are obtained.

6. The automobile interior ceiling according to claim 1, characterized in that: The heat-expandable microspheres are one of methyl methacrylate copolymer microspheres and core-shell structure hydrocarbon microspheres.

7. The automobile interior ceiling according to claim 6, characterized in that: The heat-expandable microspheres are methyl methacrylate copolymer microspheres.

8. The automobile interior ceiling according to claim 7, characterized in that: The initial particle size of the methyl methacrylate copolymer microspheres is 20-40 μm.

9. The automobile interior ceiling according to claim 1, characterized in that: The preparation method of the modified polypropylene fiber comprises the following steps: blending polypropylene particles with maleic anhydride and an initiator, melt grafting at 180-200° C., and drawing and cooling to obtain the modified polypropylene fiber.

10. The method for preparing the automobile interior ceiling according to any one of claims 1 to 9, characterized in that: The following steps are involved: 1) The substrate is heated to a surface temperature of 160-170°C. The robot places 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 positioned below the fabric. The upper mold automatically falls, and pressure is maintained to form the roof prototype. 2) The ceiling prototype is placed in a punching die and positioned using the shape of the skylight opening. The punching press maintains a holding pressure of 200-220 bar for 5-7 seconds. The punching die is equipped with a floating platen and a cold die and cold knife. The cold die and cold knife punch out excess side holes to obtain the ceiling base. 3) The skylight base material and fabric of the roof base are integrally rolled and covered to obtain the automobile interior ceiling.

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