PET (Polyethylene Terephthalate) base material automobile roof and preparation process thereof

Abstract

The invention relates to the technical field of automobile roofs, and particularly discloses a PET base material automobile roof and a preparation process thereof. The PET base material automobile roof comprises a non-woven fabric layer, a reinforcing layer, a PET base layer, a reinforcing layer and a facing layer which are sequentially compounded, the PET base layer is made of a PET foaming material, the reinforcing layer comprises a polyester material, and the mass ratio of the single reinforcing layer to the PET base layer is (0.8-2): 1; in addition, the preparation method disclosed by the invention has the advantage of reducing the recycling difficulty of the automobile roof.

Description

Technical Field

[0001] The present application relates to the technical field of automobile ceilings, and more specifically, to a PET-based automobile ceiling and a preparation process thereof. Background Art

[0002] At present, in the automotive industry, in order to reduce vehicle weight, improve fuel efficiency and enhance riding comfort, various composite materials are widely used to make car interior decoration parts. Among them, the car roof is one of the important components. Its material selection not only affects the aesthetics and thermal insulation performance of the car interior, but also affects the safety and environmental protection characteristics of the whole vehicle. In recent years, with the continuous enhancement of people's awareness of environmental protection and the advancement of technology, a variety of new environmentally friendly materials have appeared on the market for use in the manufacture of car roofs.

[0003] Existing car roofs often use polyurethane foam material as the core layer, but because polyurethane itself is difficult to degrade and is tightly bonded to other materials and is not easy to separate and process, the discarded car roof becomes a difficult-to-process waste. The base material made by mixing polypropylene short fibers and glass fibers through needle punching is difficult to separate after the two are mixed. The above-mentioned common car roofs have great limitations in resource recycling. Summary of the invention

[0004] In order to reduce the difficulty of recycling automobile roofs, the present application provides a PET-based automobile roof and a preparation process thereof.

[0005] In the first aspect, the present application provides a PET-based automobile ceiling, which adopts the following technical solution: A PET-based automobile ceiling comprises a non-woven fabric layer, a reinforcing layer, a PET base layer, a reinforcing layer and a surface finishing layer which are compounded in sequence, wherein the PET base layer is a PET foam material, the reinforcing layer comprises a polyester material, and the mass ratio of the single reinforcing layer to the PET base layer is (0.8-2):1.

[0006] By adopting the above technical scheme, the prepared automobile roof is composed of PET foam material, polyester material, non-woven fabric and a small amount of reinforcing agent. After the surface non-woven fabric layer is removed, the polyester content in the material is extremely high, and the material can be directly recycled. The material of each layer is uniform, and the difficulty of material recycling is reduced. At the same time, the PET base layer adopts PET foam material with a low density, so that the prepared PET-based automobile roof has a low density. The reinforcement layer formed by the polyester material is covered on both sides of the PET base layer, so that the automobile roof has good bending strength and resistance to cold and hot aging, which improves the performance of the automobile roof, extends its service life, and makes the recycling difficulty of the automobile roof lower, which is conducive to recycling and reuse.

[0007] Preferably, the reinforcing layer material is one or more of PET and its copolymers, PEN and its copolymers, PCTG and its copolymers, PETG and its copolymers, and the thermal deformation temperature is ≥80°C.

[0008] By adopting the above technical solution, the main material of the reinforcing layer is polyester material, which can be recycled together with the PET base layer without the need for separation and other operations, thereby reducing the difficulty and recovery rate of recycling.

[0009] Preferably, the reinforcement layer further comprises a reinforcing agent, the amount of the reinforcing agent added to the reinforcement layer is 2.83-6.56wt%, and the reinforcing agent comprises modified carbon fiber and bamboo fiber in a mass ratio of (1.59-1.72):(0.85-1.06).

[0010] By adopting the above technical scheme, fibrous modified carbon fiber and bamboo fiber form a reinforcing agent which is mixed and entangled with the polyester material in the reinforcement layer, which effectively improves the tensile strength and bending strength of the reinforcement layer, which is beneficial to increasing the service life of the car roof. At the same time, the amount of reinforcing agent added is small, which does not affect the lightweight and recycling difficulty of the car roof.

[0011] Preferably, the modified carbon fiber is carbon fiber coated with graphene oxide.

[0012] By adopting the above technical solution, the carbon fiber modified with graphene oxide has a higher specific surface area and a relatively rough surface, which is beneficial to improving the bonding strength between the modified carbon fiber and the polyester material. At the same time, the composite of the two can effectively improve the mechanical properties and bending properties of the reinforcement layer.

[0013] Preferably, the preparation method of the modified carbon fiber is as follows: graphene oxide is ultrasonically dispersed in N,N-dimethylformamide to obtain a graphene oxide dispersion, carbon fiber is ultrasonically dispersed in acetone, refluxed at 70°C for 24 hours, washed, dried, and added to the graphene oxide dispersion, the pH is adjusted to 10 with sodium hydroxide solution, electrophoretic deposition is performed, and the electrode distance is 1 cm and the voltage is 30V for 1 hour, centrifuged, separated, and dried to obtain the modified carbon fiber.

[0014] By adopting the above technical solution, graphene oxide is uniformly deposited on the surface of carbon fiber through electrophoretic deposition, thereby realizing the grafting process of graphene oxide and carbon fiber.

[0015] Preferably, the concentration of the graphene oxide dispersion is 0.25-0.31 mg / mL, and the mass ratio of graphene oxide to carbon fiber is (0.34-0.42):(2.25-2.62).

[0016] By adopting the above technical solution, the concentration of the graphene oxide dispersion and the mass ratio of graphene oxide to carbon fiber are controlled, thereby effectively controlling the deposition and grafting effect of graphene oxide on the surface of carbon fiber, which is beneficial to the uniform deposition of graphene oxide.

[0017] Preferably, the graphene oxide is subjected to the following treatment before being dispersed in N,N-dimethylformamide: ultrasonically dispersing the graphene oxide in N,N-dimethylformamide to obtain a graphene oxide suspension, mixing 4,4'-diphenylmethane diisocyanate and N,N-dimethylformamide and heating to 60°C, adding the graphene oxide suspension dropwise, adding an organic tin catalyst, keeping the reaction warm for 8 hours, centrifuging, separating, and drying.

[0018] By adopting the above technical scheme, isocyanate groups are grafted on the surface of graphene oxide. The polyester material contains more hydroxyl groups and ester bonds. The graphene oxide after grafting can be cross-linked with the polyester material, which can not only improve the strength of the reinforcing layer, but also help to improve the bonding strength between the PET base layer and the reinforcing layer.

[0019] Preferably, the mass ratio of the graphene oxide to 4,4'-diphenylmethane diisocyanate is (0.45-0.54):(8.22-9.35).

[0020] By adopting the above technical solution, the mass ratio of graphene oxide to 4,4'-diphenylmethane diisocyanate is controlled, thereby controlling the grafting amount of isocyanate groups.

[0021] In a second aspect, the present application provides a preparation process for a PET-based automobile ceiling, which adopts the following technical solution: A preparation process for a PET-based automobile ceiling comprises the following steps: using a PET foam material as a PET base layer, compounding the raw material of a reinforcement layer on both sides of the PET base layer by a double-sided lamination method to form a reinforcement layer, covering a non-woven fabric on one side of the reinforcement layer to form a non-woven fabric layer, compounding a surface finishing layer, and molding to obtain a PET-based automobile ceiling.

[0022] By adopting the above technical solution, the prepared PET-based automobile roof is lightweight and has good mechanical properties and recycling performance.

[0023] In summary, this application has the following beneficial effects: 1. Since the automobile roof in the present application is composed of PET foam material, polyester material, non-woven fabric and a small amount of reinforcing agent, after the surface non-woven fabric layer is removed, the polyester content in the material is extremely high, and it can be directly recycled. The material of each layer is unified, and the difficulty of material recycling is reduced. At the same time, the PET base layer adopts PET foam material with a low density, so that the prepared PET-based automobile roof has a low density. The reinforcement layer formed by the polyester material is covered on both sides of the PET base layer, so that the automobile roof has good bending strength and resistance to cold and hot aging, which improves the performance of the automobile roof and extends its service life. At the same time, the recycling difficulty of the automobile roof is relatively low, which is conducive to recycling and reuse.

[0024] 2. In the present application, the fibrous modified carbon fiber and bamboo fiber are mixed and wound with the polyester material in the reinforcement layer, and the amount of reinforcing agent added is relatively small. This can effectively improve the strength of the reinforcement layer without affecting the lightweight and recycling difficulty of the car roof, thereby improving the strength of the car roof.

[0025] 3. The carbon fiber modified with graphene oxide in this application has a higher specific surface area and a relatively rough surface, which is beneficial to improving the bonding strength between the modified carbon fiber and the polyester material. At the same time, the composite of the two can effectively improve the mechanical properties and bending properties of the reinforcement layer. DETAILED DESCRIPTION

[0026] The present application is further described in detail below in conjunction with embodiments. Preparation Example 1-10 of Modified Carbon Fiber

[0027] Preparation Example 1 Preparation method of modified carbon fiber: ultrasonically disperse graphene oxide in 200 mL of N,N-dimethylformamide to obtain a graphene oxide dispersion, the concentration of the graphene oxide dispersion is 0.25 mg / mL, ultrasonically disperse carbon fiber in 150 mL of acetone, reflux at 70°C for 24 hours, wash, dry, and add to the graphene oxide dispersion, the mass ratio of graphene oxide to carbon fiber is 0.34:2.25, adjust the pH to 10 with sodium hydroxide solution, use electrophoretic deposition, operate for 1 hour at an electrode distance of 1 cm and a voltage of 30 V, centrifuge, separate, and dry to obtain modified carbon fiber.

[0028] Preparation Example 2 Preparation method of modified carbon fiber: ultrasonically disperse graphene oxide in 200 mL of N,N-dimethylformamide to obtain a graphene oxide dispersion, the concentration of the graphene oxide dispersion is 0.31 mg / mL, ultrasonically disperse carbon fiber in 150 mL of acetone, reflux at 70°C for 24 hours, wash, dry, and add to the graphene oxide dispersion, the mass ratio of graphene oxide to carbon fiber is 0.42:2.62, adjust the pH to 10 with sodium hydroxide solution, use electrophoretic deposition, operate for 1 hour at an electrode distance of 1 cm and a voltage of 30 V, centrifuge, separate, and dry to obtain modified carbon fiber.

[0029] Preparation Example 3 The difference between Preparation Example 3 and Preparation Example 1 is that in Preparation Example 3, the concentration of the graphene oxide dispersion is 0.05 mg / mL.

[0030] Preparation Example 4 The difference between Preparation Example 4 and Preparation Example 1 is that in Preparation Example 4, the concentration of the graphene oxide dispersion is 0.56 mg / mL.

[0031] Preparation Example 5 The difference between Preparation Example 5 and Preparation Example 1 is that in Preparation Example 5, the mass ratio of graphene oxide to carbon fiber is 0.34:1.25.

[0032] Preparation Example 6 The difference between Preparation Example 6 and Preparation Example 1 is that in Preparation Example 6, the mass ratio of graphene oxide to carbon fiber is 0.34:4.95.

[0033] Preparation Example 7 The difference between Preparation Example 7 and Preparation Example 1 is that in Preparation Example 7, the graphene oxide is subjected to the following treatment before being dispersed in N,N-dimethylformamide: the graphene oxide is ultrasonically dispersed in 15 mL of N,N-dimethylformamide to obtain a graphene oxide suspension, 8 g of 4,4'-diphenylmethane diisocyanate is mixed with 15 mL of N,N-dimethylformamide and the temperature is raised to 60°C, the graphene oxide suspension is added dropwise, and 1-2 mL of dibutyltin dilaurate is added, the reaction is kept warm for 8 hours, centrifuged, separated, and dried, and the mass ratio of graphene oxide to 4,4'-diphenylmethane diisocyanate is 0.45:8.22.

[0034] Preparation Example 8 The difference between Preparation Example 8 and Preparation Example 1 is that in Preparation Example 8, the graphene oxide is subjected to the following treatment before being dispersed in N,N-dimethylformamide: the graphene oxide is ultrasonically dispersed in 15 mL of N,N-dimethylformamide to obtain a graphene oxide suspension, 8 g of 4,4'-diphenylmethane diisocyanate is mixed with 15 mL of N,N-dimethylformamide and the temperature is raised to 60°C, the graphene oxide suspension is added dropwise, and 1-2 mL of dibutyltin dilaurate is added, the reaction is kept warm for 8 hours, centrifuged, separated, and dried, and the mass ratio of graphene oxide to 4,4'-diphenylmethane diisocyanate is 0.54:9.35.

[0035] Preparation Example 9 The difference between Preparation Example 9 and Preparation Example 7 is that in Preparation Example 9, the mass ratio of graphene oxide to 4,4'-diphenylmethane diisocyanate is 0.45:5.62.

[0036] Preparation Example 10 The difference between Preparation Example 10 and Preparation Example 7 is that in Preparation Example 10, the mass ratio of graphene oxide to 4,4'-diphenylmethane diisocyanate is 0.45:11.26. Example

[0037] Example 1 A PET-based automobile ceiling comprises a non-woven fabric layer, a reinforcing layer, a PET base layer, a reinforcing layer and a surface finishing layer which are compounded in sequence, wherein the PET base layer is a PET foam material, the reinforcing layer comprises a polyester material, the mass ratio of the single reinforcing layer to the PET base layer is 0.8:1, the reinforcing layer material is a mixture of PET, PET copolymer, PEN and PCTG copolymer, and the thermal deformation temperature is ≥80°C.

[0038] The preparation method of the above-mentioned PET-based automobile ceiling comprises the following steps: using PET foam material as the PET base layer, compounding the raw materials of the reinforcement layer on both sides of the PET base layer by double-sided lamination to form a reinforcement layer, and covering the reinforcement layer on one side with non-woven fabric to form a non-woven fabric layer, and then compounding the surface finishing layer, and molding and shaping to obtain the PET-based automobile ceiling.

[0039] Example 2 A PET-based automobile roof comprises a non-woven fabric layer, a reinforcing layer, a PET base layer, a reinforcing layer and a surface finishing layer which are compounded in sequence, wherein the PET base layer is a PET foaming material, the reinforcing layer comprises a polyester material, the mass ratio of the single reinforcing layer to the PET base layer is 2:1, the reinforcing layer material is a mixture of a PET copolymer and a PETG copolymer, and the thermal deformation temperature is ≥80°C.

[0040] The preparation method of the above-mentioned PET-based automobile ceiling comprises the following steps: using PET foam material as the PET base layer, compounding the raw materials of the reinforcement layer on both sides of the PET base layer by double-sided lamination to form a reinforcement layer, and covering the reinforcement layer on one side with non-woven fabric to form a non-woven fabric layer, and then compounding the surface finishing layer, and molding and shaping to obtain the PET-based automobile ceiling.

[0041] Example 3 A PET-based automobile roof comprises a non-woven fabric layer, a reinforcing layer, a PET base layer, a reinforcing layer and a surface finishing layer which are compounded in sequence, wherein the PET base layer is a PET foam material, the reinforcing layer comprises a polyester material, the mass ratio of the single reinforcing layer to the PET base layer is 1.2:1, the reinforcing layer material is a mixture of a PEN copolymer and a PCTG copolymer, and the thermal deformation temperature is ≥80°C.

[0042] The preparation method of the above-mentioned PET-based automobile ceiling comprises the following steps: using PET foam material as the PET base layer, compounding the raw materials of the reinforcement layer on both sides of the PET base layer by double-sided lamination to form a reinforcement layer, and covering the reinforcement layer on one side with non-woven fabric to form a non-woven fabric layer, and then compounding the surface finishing layer, and molding and shaping to obtain the PET-based automobile ceiling.

[0043] Example 4 The difference between Example 4 and Example 1 is that in Example 4, the reinforcing layer also includes a reinforcing agent, the amount of the reinforcing agent added to the reinforcing layer is 2.83wt%, and the reinforcing agent includes modified carbon fiber and bamboo fiber in a mass ratio of 1.59:0.85, and the modified carbon fiber is the modified carbon fiber prepared in Preparation Example 1.

[0044] Example 5 The difference between Example 5 and Example 1 is that in Example 5, the reinforcing layer also includes a reinforcing agent, the amount of the reinforcing agent added to the reinforcing layer is 6.56wt%, and the reinforcing agent includes modified carbon fiber and bamboo fiber in a mass ratio of 1.72:1.06, and the modified carbon fiber is the modified carbon fiber obtained in Preparation Example 2.

[0045] Example 6 The difference between Example 6 and Example 4 is that in Example 6, the amount of the reinforcing agent added to the reinforcement layer is 1.25 wt %.

[0046] Example 7 The difference between Example 7 and Example 4 is that in Example 7, the amount of the reinforcing agent added to the reinforcement layer is 8.62 wt %.

[0047] Example 8 The difference between Example 8 and Example 4 is that in Example 8, in the reinforcing agent, the mass ratio of the modified carbon fiber to the bamboo fiber is 1.59:0.25.

[0048] Example 9 The difference between Example 9 and Example 4 is that in Example 9, in the reinforcing agent, the mass ratio of the modified carbon fiber to the bamboo fiber is 1.59:2.62.

[0049] Example 10 The difference between Example 10 and Example 4 is that in Example 10, the modified carbon fiber is the modified carbon fiber prepared in Preparation Example 3.

[0050] Embodiment 11 The difference between Example 11 and Example 4 is that in Example 11, the modified carbon fiber is the modified carbon fiber prepared in Preparation Example 4.

[0051] Example 12 The difference between Example 12 and Example 4 is that in Example 12, the modified carbon fiber is the modified carbon fiber prepared in Preparation Example 5.

[0052] Embodiment 13 The difference between Example 13 and Example 4 is that in Example 13, the modified carbon fiber is the modified carbon fiber prepared in Preparation Example 6.

[0053] Embodiment 14 The difference between Example 14 and Example 4 is that in Example 14, the modified carbon fiber is the modified carbon fiber prepared in Preparation Example 7.

[0054] Embodiment 15 The difference between Example 15 and Example 4 is that in Example 15, the modified carbon fiber is the modified carbon fiber prepared in Preparation Example 8.

[0055] Example 16 The difference between Example 16 and Example 4 is that in Example 16, the modified carbon fiber is the modified carbon fiber prepared in Preparation Example 9.

[0056] Embodiment 17 The difference between Example 17 and Example 4 is that in Example 17, the modified carbon fiber is the modified carbon fiber prepared in Preparation Example 10.

[0057] Embodiment 18 The difference between Example 18 and Example 4 is that in Example 18, an equal amount of modified carbon fiber is used instead of the reinforcing agent.

[0058] Embodiment 19 The difference between Example 19 and Example 4 is that in Example 19, an equal amount of bamboo fiber is used instead of the reinforcing agent. Performance testing

[0059] According to the raw materials and preparation process of Examples 1-19, an automobile roof was prepared.

[0060] 1. Test its tensile strength and record it in Table 1. The tensile strength refers to the standard GB / T 1499-2005.

[0061] 2. The test method for the bending strength of the automobile roof is as follows: Select a bending fixture with a support base and a pressure head of R=10±0.02mm and install it on the universal testing machine. Adjust the support point span to 152mm. Place the 76×305mm sample with the fabric layer removed on the bending fixture. Set the test speed to 13mm / min. The test end condition is a deflection of 6.3mm. Run the test. After the test, read the maximum value of the loading force and take the average value. Record the results in Table 1.

[0062] 3. Car roof undergoes cyclic aging test, the test method is as follows: Cycle 1: Place the sample in the following conditions in sequence and repeat 10 times: (1) -30°C, 4 h; (2) 75°C, 4 h; (3) 38°C, 95% humidity, 16 h.

[0063] Cycle 2: Place the sample in the following environments in turn and repeat 5 times: (1) 90°C, 4 h; (2) room temperature, 0.5 h; (3) -30°C, 1.5 h; (4) room temperature, 0.5 h; (5) 70°C, 95% humidity, 3 h; (6) room temperature, 0.5 h; (7) -30°C, 1.5 h; (8) room temperature, 0.5 h.

[0064] The sample was subjected to cycle 1 and cycle 2 respectively, and the deformation of the automobile roof before and after the test was tested by laser dot ranging. When the deformation of the general area of ​​the automobile roof was ≤10mm, the deformation of the sunroof opening area was ≤2mm, and the deformation of the front and rear edges was ≤2mm, it was recorded as qualified. Otherwise, it was unqualified. The test results are recorded in Table 1.

[0065] Table 1 Performance test of car roof project Tensile strength / MPa Bending strength / N Loop 1 Loop 2 Example 1 21.13 12.68 qualified Failure Example 2 21.72 12.93 qualified Failure Example 3 21.48 12.72 qualified Failure Example 4 25.62 15.26 qualified qualified Example 5 25.91 15.62 qualified qualified Example 6 22.72 14.23 qualified Failure Example 7 22.95 14.61 qualified Failure Example 8 22.65 14.82 qualified Failure Example 9 23.01 14.38 qualified Failure Example 10 22.76 14.57 qualified Failure Embodiment 11 23.12 14.76 qualified Failure Example 12 22.68 14.38 qualified Failure Embodiment 13 22.92 14.73 qualified Failure Embodiment 14 27.96 16.35 qualified qualified Embodiment 15 28.01 16.59 qualified qualified Example 16 26.01 15.98 qualified qualified Embodiment 17 26.81 16.01 qualified qualified Embodiment 18 23.05 13.95 qualified Failure Embodiment 19 23.95 14.06 qualified Failure Compared with comparative examples 1-3, the automobile roof prepared in examples 1-3 has better tensile strength and bending strength, and the result of the cyclic aging test is better. After the automobile roof is treated with cycle 1, the deformation of the automobile roof is within the standard requirement range and meets the requirements. When preparing the automobile roof of examples 1-3, a reinforcing layer is made of polyester material and covered on both sides of the PET base layer. After the non-woven fabric layer and the surface finishing layer on the surface are removed, the main component of each layer of material is polyester, which can be directly recycled. At the same time, since the composition of each layer of material is relatively uniform, there is no need to perform too much separation and impurity removal operations, and the recycling difficulty is relatively low. The PET base layer adopts PET foam material, which has low density and good strength. Covering the reinforcing layer on both sides of the PET base layer can further improve the bending strength and cold and hot aging resistance of the automobile roof, improve the performance of the automobile roof, and extend its service life. At the same time, since the reinforcing layer adopts polyester material, it can be recycled together with the PET base layer, the recycling difficulty of the automobile roof is reduced, and resources can be fully reused.

[0066] Compared with Examples 1-3, the car roof prepared in Example 4-5 has better tensile strength and bending strength. After the car roof is treated with Cycle 1 and Cycle 2, the deformation of the car roof meets the requirements. A reinforcing agent is also added to the car roof prepared in Example 4-5. The reinforcing agent includes modified carbon fiber and bamboo fiber. The addition of bamboo fiber and modified carbon fiber can effectively improve the mechanical properties of the reinforcement layer. The fibrous modified carbon fiber and bamboo fiber are mixed and entangled with the polyester material in the reinforcement layer. When the added amount is small, the strength of the reinforcement layer can be effectively improved. Without affecting the lightweight and recycling difficulty of the car roof, the strength of the car roof is improved, and the service life of the car roof is extended.

[0067] Compared with Examples 4-5, the tensile strength and bending strength of the automobile roof prepared in Example 6-7 are decreased, and the cycle 2 line test of the cyclic aging test does not meet the requirements. When preparing the automobile roof of Example 6-7, the amount of the reinforcing agent added in the reinforcement layer is changed, indicating that the amount of the reinforcing agent used has an impact on the performance of the automobile roof. The amount of the reinforcing agent added is reduced in Example 6, and the amount of the reinforcing agent added is increased in Example 7. The reduction in the amount of the reinforcing agent added will affect the reinforcing effect of the modified carbon fiber and the bamboo fiber on the reinforcement layer, thereby reducing the strength of the automobile roof, while the increase in the amount of the reinforcing agent added affects the dispersibility of the reinforcing agent in the reinforcement layer, the dispersion of the modified carbon fiber is weakened, and the distribution is uneven, which in turn affects the bonding strength between the reinforcing agent and the polyester material, thereby reducing the strength of the automobile roof.

[0068] Compared with Example 4-5, the tensile strength and bending strength of the automobile roofs prepared in Examples 8-9 and 18-19 are decreased, and the cycle 2 line test of the cyclic aging test does not meet the requirements. Example 8-9 changes the mass ratio of modified carbon fiber and bamboo fiber in the reinforcing agent, and only modified carbon fiber is added in Example 18, and only bamboo fiber is added in Example 19. It can be seen from Table 1, Examples 4-5, Examples 8-9 and Examples 18-19 that there is a synergistic effect between modified carbon fiber and bamboo fiber, and the reinforcing agent formed by the compound of the two significantly improves the strength of the reinforcement layer, thereby improving the strength of the automobile roof, making the automobile roof less susceptible to deformation due to temperature during use, thereby improving the service life of the automobile roof.

[0069] Compared with Examples 4-5, the tensile strength and bending strength of the automobile roof prepared in Example 10-13 decreased, and the cycle 2 line test of the cyclic aging test did not meet the requirements. The concentration of the graphene oxide dispersion was changed during the preparation of the modified carbon fiber used in Example 10-11. The mass ratio of graphene oxide to carbon fiber was changed during the preparation of the modified carbon fiber used in Examples 12-13. The concentration of the graphene oxide dispersion affects the effect of electrophoretic deposition. A lower concentration or a lower mass results in a smaller amount of graphene oxide deposited on the surface of the carbon fiber. A higher concentration or a higher mass results in uneven and excessive graphene oxide deposition on the surface of the carbon fiber, which in turn affects the improvement effect of the modified carbon fiber on the reinforcement layer.

[0070] Compared with Examples 4-5, the tensile strength and bending strength of the automobile roof prepared in Examples 14-15 are improved, and the cycle 2 line test of the cyclic aging test meets the requirements. During the preparation of the modified carbon fiber used in Examples 14-15, the graphene oxide is grafted with isocyanate groups, and the isocyanate groups are grafted on the surface of the graphene oxide. The polyester material contains more hydroxyl groups and ester bonds. The grafted graphene oxide can be cross-linked with the polyester material, which can not only improve the strength of the reinforcement layer, but also help to improve the bonding strength between the PET base layer and the reinforcement layer.

[0071] Compared with Examples 14-15, the tensile strength and bending strength of the automobile roof prepared in Examples 16-17 decreased, and the cycle 2 line test of the cyclic aging test met the requirements. During the preparation of the modified carbon fiber used in Examples 16-17, the mass ratio of graphene oxide to 4,4'-diphenylmethane diisocyanate was changed, which directly affected the grafting amount of isocyanate groups on the surface of graphene oxide, thereby affecting the bonding strength between the modified carbon fiber and the polyester material. The polarity of the isocyanate group is relatively strong, and agglomeration is likely to occur when the grafting amount is increased, while the bonding strength between the modified carbon fiber and the polyester material is likely to be weakened when the grafting amount is reduced.

[0072] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A PET-based automobile ceiling, characterized in that: It includes a non-woven fabric layer, a reinforcing layer, a PET base layer, a reinforcing layer and a surface finishing layer which are compounded in sequence, wherein the PET base layer is a PET foam material, the reinforcing layer includes a polyester material, and the mass ratio of a single reinforcing layer to the PET base layer is (0.8-2):

1.

2. A PET-based automobile ceiling according to claim 1, characterized in that: The reinforcing layer material is one or more of PET and its copolymers, PEN and its copolymers, PCTG and its copolymers, PETG and its copolymers, and the thermal deformation temperature is ≥80°C.

3. The PET-based automobile ceiling according to claim 1, characterized in that: The reinforcement layer also includes a reinforcing agent, the amount of the reinforcing agent added to the reinforcement layer is 2.83-6.56wt%, and the reinforcing agent includes modified carbon fiber and bamboo fiber in a mass ratio of (1.59-1.72): (0.85-1.06).

4. A PET-based automobile ceiling according to claim 3, characterized in that: The modified carbon fiber is carbon fiber coated with graphene oxide.

5. A PET-based automobile ceiling according to claim 4, characterized in that: The preparation method of the modified carbon fiber comprises the following steps: ultrasonically dispersing graphene oxide in N,N-dimethylformamide to obtain a graphene oxide dispersion liquid, ultrasonically dispersing carbon fiber in acetone, refluxing at 70° C. for 24 hours, washing, drying, adding the carbon fiber to the graphene oxide dispersion liquid, adjusting the pH value to 10 with a sodium hydroxide solution, using electrophoretic deposition, operating at an electrode distance of 1 cm and a voltage of 30 V for 1 hour, centrifuging, separating, and drying to obtain the modified carbon fiber.

6. A PET-based automobile ceiling according to claim 5, characterized in that: The concentration of the graphene oxide dispersion is 0.25-0.31 mg / mL, and the mass ratio of graphene oxide to carbon fiber is (0.34-0.42):(2.25-2.62).

7. The PET-based automobile ceiling according to claim 5, characterized in that: The graphene oxide is subjected to the following treatment before being dispersed in N,N-dimethylformamide: the graphene oxide is ultrasonically dispersed in N,N-dimethylformamide to obtain a graphene oxide suspension, 4,4'-diphenylmethane diisocyanate is mixed with N,N-dimethylformamide and the mixture is heated to 60° C., the graphene oxide suspension is added dropwise, an organic tin catalyst is added, the mixture is kept warm for reaction for 8 hours, centrifuged, separated, and dried.

8. The PET-based automobile ceiling according to claim 7, characterized in that: The mass ratio of the graphene oxide to 4,4'-diphenylmethane diisocyanate is (0.45-0.54):(8.22-9.35).

9. The process for preparing a PET-based automobile ceiling according to any one of claims 1 to 8, characterized in that: The following steps are involved: The PET foam material is used as the PET base layer, and the raw materials of the reinforcement layer are compounded on both sides of the PET base layer by double-sided lamination to form a reinforcement layer, and non-woven fabric is covered on one side of the reinforcement layer to form a non-woven fabric layer, and then the surface finishing layer is compounded and molded to produce a PET-based car roof.