PCU car cover with ductility and production process thereof

Abstract

The invention discloses a malleable PCU car cover and a production process thereof, and relates to the technical field of car cover materials, the malleable PCU car cover comprises the following raw materials by weight: 100 parts of a polycarbonate polyurethane elastomer, 5-15 parts of a flexibilizer, 0.3-0.5 part of an antioxidant, and 0.3-0.7 part of an ultraviolet light absorber; the toughening agent is a core-shell type PUR (Polyurethane)-ACR (Acrylic Acid)-OH toughening agent; the preparation method comprises the following steps: S1, premixing and drying the raw materials; s2, feeding the dried raw materials into a single-screw extruder for melting; s3, molding the molten mixture through a mouth mold to obtain an extrusion cast film; s4, the casting film is cooled through a ceramic roller and a rubber roller, and the thickness is adjusted; and S5, trimming and winding the obtained film to obtain the PCU car cover with ductility. The PCU car cover provided by the invention has excellent weather resistance and mechanical strength.

Description

Technical Field

[0001] This application relates to the field of car cover materials technology, and in particular to a stretchable PCU car cover and its manufacturing process. Background Technology

[0002] When cars are used outdoors, they are constantly exposed to a combination of environmental stresses, including sand and dust erosion, acid rain corrosion, hail impact, and ultraviolet radiation, leading to irreversible damage to the paint such as cracking, fading, and other issues. Traditional protective measures such as waxing and polishing require frequent maintenance, increasing both economic and time costs, and their short protection period fails to meet car owners' needs for "long-lasting protection." Against this backdrop, car wraps (car paint protection films) are gradually becoming the mainstream solution.

[0003] Thermoplastic polyurethane has become the mainstream choice for high-end car cover substrates due to its excellent toughness, high strength, non-toxicity, odorlessness, and excellent heat processing properties. Existing car covers are mainly films made from polyurethane elastomer granules through special processes such as calendering, casting, blown film production, and coating. They are increasingly popular due to their superior performance and environmental friendliness. However, traditional polyether or polyester-based polyurethane elastomer car cover substrates generally have low elongation at break, and the material is prone to hardening and embrittlement, especially at low temperatures, making it difficult to adhere to complex curved surfaces and leading to problems such as whitening, cracking, and edge curling during installation. Summary of the Invention

[0004] In order to provide a PCU car cover with strong weather resistance and excellent extensibility, this application provides a PCU car cover with extensibility and its manufacturing process.

[0005] This application provides a stretchable PCU car cover, which adopts the following technical solution: A stretchable PCU car cover, the raw materials by weight include 100 parts polycarbonate-type polyurethane elastomer, 5-15 parts toughening agent, 0.3-0.5 parts antioxidant, and 0.3-0.7 parts ultraviolet absorber; The toughening agent is a core-shell type PUR-ACR-OH toughening agent.

[0006] Preferably, the raw materials include, by weight, 100 parts of polycarbonate-type polyurethane elastomer, 10 parts of core-shell type PUR-ACR-OH toughening agent, 0.4 parts of antioxidant, and 0.5 parts of ultraviolet absorber.

[0007] Preferably, the polyurethane elastomer is prepared from the following raw materials in parts by weight: 50-60 parts polycarbonate diol, 250-300 parts tetrahydrofuran, 9-10.5 parts 4,4-diisocyanate dicyclohexylmethane, and 2.2-2.6 parts 1,4-butanediol.

[0008] Preferably, the polycarbonate diol is prepared from the following raw materials in parts by weight: 20-40 parts diphenyl carbonate, 6.7-13.4 parts 1,8-octanediol, 9.2-18.4 parts 1,12-dodecanediol, and 0.004-0.008 parts catalyst.

[0009] Preferably, the method for preparing the polycarbonate diol includes the following steps: Diphenyl carbonate, 1,8-octanediol, and 1,12-dodecanediol were mixed and heated to 160-200℃ under nitrogen protection. After the substances were completely melted, a catalyst was added, and the polycondensation reaction was carried out for 2-3 hours. Then, the mixture was distilled under reduced pressure for 30-60 minutes. After stopping the reaction, the product was cooled to room temperature and then dissolved in tetrahydrofuran. Methanol was added and stirred for 2-3 hours. The mixture was then vacuum filtered and the precipitate was collected. The precipitate was washed with methanol for 2-3 hours and then filtered again to collect the precipitate. After drying, polycarbonate diol was obtained.

[0010] Preferably, the method for preparing the polycarbonate-type polyurethane elastomer includes the following steps: Polycarbonate diol was added to tetrahydrofuran and stirred at 100-150 rpm until completely dissolved. Then, under nitrogen protection, 4,4-diisocyanate dicyclohexylmethane was added dropwise at 60-70℃ and 400-500 rpm. After the addition was complete, 1,4-butanediol was added while stirring at 1000-1200 rpm. After reacting for 30-45 min, the reactants were placed at 50-60℃ for 12-16 h, then heated to 100-110℃ and placed for 2-3 h. Finally, the temperature was raised to 120-130℃ and aged for 24-28 h to obtain polycarbonate-type polyurethane elastomer.

[0011] Preferably, the preparation method of the core-shell type PUR-ACR-OH toughening agent includes the following steps: T1. By weight, mix 4-8 parts of polypropylene glycol, 2-4 parts of hexamethylene diisocyanate, and 17.5-35 parts of butyl acrylate, and stir at room temperature for 1-2 hours; then add 0.5-1 parts of hydroxyethyl acrylate, and continue stirring at room temperature for 20-30 minutes to obtain a polyurethane prepolymer. T2. Add 2.5-5 parts butyl acrylate, 0.1-0.2 parts allyl methacrylate, 0.25-0.5 parts sodium dodecyl sulfate, 0.025-0.05 parts ammonium persulfate, and 0.025-0.05 parts sodium bicarbonate to 50-100 parts deionized water. Heat to 65-75℃ at 300-500 rpm and react for 30-40 minutes to obtain PBA seed latex particles. T3. The polyurethane prepolymer obtained in T1 is dropped into the PBA seed latex particles obtained in T2, and 0.3-0.4 parts of ammonium persulfate are added. After reacting for 2-3 hours, PUR-ACR latex particles are obtained. T4. Mix 7.5-15 parts of ammonium persulfate and 1.5-3 parts of hydroxyethyl acrylate, then add the mixture dropwise to the PUR-ACR latex particles obtained in T3, and add 0.05-0.1 parts of ammonium persulfate. After reacting for 2-3 hours, cool to room temperature, and discharge the material to obtain PUR-ACR-OH latex particles. T5. Add ethanol to the PUR-ACR-OH latex particles obtained in T4 and freeze for 24-30 hours to demulsify. Then dry in a forced-air dryer at 60-70℃ for 12-16 hours to obtain the core-shell type PUR-ACR-OH toughening agent.

[0012] Preferably, the antioxidant comprises antioxidant 168 and antioxidant 1010 in a mass ratio of 1:1-2; The ultraviolet absorber is one or more of benzotriazole ultraviolet absorbers, triazine ultraviolet absorbers, and hindered amine light stabilizers.

[0013] This application provides a manufacturing process for a stretchable PCU car cover, employing the following technical solution: A manufacturing process for a stretchable PCU car cover includes the following steps: S1. Premix and dry the raw materials, which include polycarbonate-type polyurethane elastomer, toughening agent, antioxidant, and ultraviolet absorber; S2. The dried raw material is fed into a single-screw extruder for melting; S3. The molten mixture is formed through a die to obtain an extruded cast film; S4. The cast film is cooled and its thickness is adjusted by using ceramic rollers and rubber rollers; S5. Trim and wind the film obtained in step S4 to obtain a PCU car cover with stretchability.

[0014] Preferably, in S2, the temperature of the feeding section of the single-screw extruder is 110-160℃, the temperature of barrel 1 is 115-125℃, the temperature of barrel 2 is 140-150℃, the temperature of barrel 3 is 150-160℃, the temperature of barrel 4 is 155-165℃, the temperature of barrel 5 is 160-170℃, the temperature of the filter screen is 160-170℃, and the screw speed is 28-32 rpm.

[0015] In summary, this application includes at least one of the following beneficial technical effects: 1. This application uses diphenyl carbonate to react with 1,8-octanediol and 1,12-dodecanediol to synthesize a polycarbonate diol with a designed molecular weight of 2000; then, 4,4-diisocyanate dicyclohexylmethane, 1,4-butanediol and the obtained polycarbonate diol are reacted to synthesize a polycarbonate-type polyurethane elastomer, which has super impact resistance, tear resistance, scratch resistance and self-healing ability, effectively solving the problems of hydrolysis and low-temperature embrittlement under high temperature and high humidity environments.

[0016] 2. This application uses emulsion seed polymerization, followed by in-situ grafting and surface functionalization, to construct a core-shell structure with rubber as the core, polyurethane as the shell, and hydroxyl crown, which has excellent low-temperature high toughness and effectively improves the ductility and weather resistance of PCU car wrap. Detailed Implementation

[0017] The present application will be further described in detail below with reference to the embodiments.

[0018] The chemical reagents used in the preparation examples, embodiments, and comparative examples provided in this invention are all commercially available products.

[0019] Preparation Example 1: Preparation of Polycarbonate-type Polyurethane Elastomers Preparation Example 1.1 E1. Mix 20g of diphenyl carbonate, 6.7g of 1,8-octanediol, and 9.2g of 1,12-dodecanediol, and heat to 160℃ under nitrogen protection. After the substances are completely melted, add 0.004g of dibutyltin dilaurate catalyst. After polycondensation reaction for 2h, distill under reduced pressure for 30min. After stopping the reaction, cool the product to room temperature, then dissolve the product in 180g of tetrahydrofuran, add 2000g of methanol and stir for 2h. Then, vacuum filter and collect the precipitate. Wash the precipitate with methanol for 2h, then filter again to collect the precipitate. After drying, polycarbonate diol is obtained. E2. Add 50g of polycarbonate diol to 250g of tetrahydrofuran and stir at 100rpm until completely dissolved. Then, under nitrogen protection, add 9g of 4,4-diisocyanate dicyclohexylmethane dropwise at 60℃ and 400rpm. After the addition is complete, add 2.2g of 1,4-butanediol while stirring at 1000rpm. After reacting for 30min, place the reactants in an oven at 50℃ for 12h, then raise the temperature to 100℃ and place for 2h. Finally, raise the temperature to 120℃ and mature for 24h to obtain polycarbonate-type polyurethane elastomer.

[0020] Preparation Example 1.2 E1. Mix 30g of diphenyl carbonate, 10.05g of 1,8-octanediol, and 13.8g of 1,12-dodecanediol. Heat the mixture to 180℃ under nitrogen protection. After the mixture is completely melted, add 0.006g of dibutyltin dilaurate catalyst. After polycondensation reaction for 2.5h, distill under reduced pressure for 45min. After stopping the reaction, cool the product to room temperature. Then dissolve the product in 200g of tetrahydrofuran, add 2100g of methanol and stir for 2.5h. After vacuum filtration, collect the precipitate. Wash the precipitate with methanol for 2.5h and then filter again to collect the precipitate. After drying, polycarbonate diol is obtained. E2. Add 55g of polycarbonate diol to 275g of tetrahydrofuran and stir at 125rpm until completely dissolved. Then, under nitrogen protection, add 9.75g of 4,4-diisocyanate dicyclohexylmethane dropwise at 65℃ and 450rpm. After the addition is complete, add 2.4g of 1,4-butanediol while stirring at 1100rpm. After reacting for 37min, place the reactants in an oven at 55℃ for 14h, then raise the temperature to 105℃ and place for 2.5h. Finally, raise the temperature to 125℃ and mature for 26h to obtain polycarbonate-type polyurethane elastomer.

[0021] Preparation Example 1.3 E1. Mix 40g of diphenyl carbonate, 13.4g of 1,8-octanediol, and 18.4g of 1,12-dodecanediol, and heat to 200℃ under nitrogen protection. After the substances are completely melted, add 0.008g of dibutyltin dilaurate catalyst. After polycondensation reaction for 3h, distill under reduced pressure for 60min. After stopping the reaction, cool the product to room temperature, then dissolve the product in 220g of tetrahydrofuran, add 2200g of methanol and stir for 3h. Then, vacuum filter and collect the precipitate. Wash the precipitate with methanol for 3h, then filter again to collect the precipitate. After drying, polycarbonate diol is obtained. E2. Add 60g of polycarbonate diol to 300g of tetrahydrofuran and stir at 150rpm until completely dissolved. Then, under nitrogen protection, add 10.5g of 4,4-diisocyanate dicyclohexylmethane dropwise at 70℃ and 500rpm. After the addition is complete, add 2.6g of 1,4-butanediol while stirring at 1200rpm. After reacting for 45min, place the reactants in an oven at 60℃ for 16h, then raise the temperature to 110℃ and place for 3h. Finally, raise the temperature to 130℃ and mature for 28h to obtain polycarbonate-type polyurethane elastomer.

[0022] Preparation Example 2: Preparation of Core-Shell Type PUR-ACR-OH Toughening Agent Preparation Example 2.1 T1. Mix 4g of polypropylene glycol 400, 2g of hexamethylene diisocyanate and 17.5g of butyl acrylate and stir at room temperature for 1 hour; then add 0.5g of hydroxyethyl acrylate and continue stirring at room temperature for 20 minutes to obtain a polyurethane prepolymer. T2. Add 2.5g butyl acrylate, 0.1g allyl methacrylate, 0.25g sodium dodecyl sulfate, 0.025g ammonium persulfate, and 0.025g sodium bicarbonate to 50g deionized water, heat to 65℃ at 300rpm, and react for 30min to obtain PBA seed latex particles. T3. The polyurethane prepolymer obtained in T1 is dropped into the PBA seed latex particles obtained in T2, and 0.3g of ammonium persulfate is added. After reacting for 2 hours, PUR-ACR latex particles are obtained. T4. Mix 7.5g ammonium persulfate and 1.5g hydroxyethyl acrylate, then add the mixture dropwise to the PUR-ACR latex particles obtained in T3, and add 0.05g ammonium persulfate. After reacting for 2 hours, cool to room temperature, and discharge the material to obtain PUR-ACR-OH latex particles. T5. Add ethanol to the PUR-ACR-OH latex particles obtained in T4 and freeze for 24 hours to demulsify. Then dry in a forced-air dryer at 60°C for 12 hours to obtain the core-shell type PUR-ACR-OH toughening agent.

[0023] Preparation Example 2.2 T1. Mix 6g of polypropylene glycol 400, 3g of hexamethylene diisocyanate, and 26.25g of butyl acrylate, and stir at room temperature for 1.5h; then add 0.75g of hydroxyethyl acrylate, and continue stirring at room temperature for 25min to obtain a polyurethane prepolymer; T2. Add 3.75g butyl acrylate, 0.15g allyl methacrylate, 0.375g sodium dodecyl sulfate, 0.0375g ammonium persulfate, and 0.0375g sodium bicarbonate to 75g deionized water, heat to 70℃ at 400rpm, and react for 35min to obtain PBA seed latex particles. T3. The polyurethane prepolymer obtained in T1 was dropped into the PBA seed latex particles obtained in T2, and 0.35g of ammonium persulfate was added. After reacting for 2.5h, PUR-ACR latex particles were obtained. T4. Mix 11.25g ammonium persulfate and 2.25g hydroxyethyl acrylate, then add the mixture dropwise to the PUR-ACR latex granules obtained in T3, and add 0.075g ammonium persulfate. After reacting for 2.5h, cool to room temperature and discharge the material to obtain PUR-ACR-OH latex granules. T5. Add ethanol to the PUR-ACR-OH latex particles obtained in T4 and freeze for 27 hours to demulsify. Then dry them at 65°C for 14 hours to obtain the core-shell type PUR-ACR-OH toughening agent.

[0024] Preparation Example 2.3 T1. Mix 8g of polypropylene glycol 400, 4g of hexamethylene diisocyanate and 35g of butyl acrylate and stir at room temperature for 2 hours; then add 0.75g of hydroxyethyl acrylate and continue stirring at room temperature for 30 minutes to obtain a polyurethane prepolymer. T2. Add 5g butyl acrylate, 0.2g allyl methacrylate, 0.5g sodium dodecyl sulfate, 0.05g ammonium persulfate, and 0.05g sodium bicarbonate to 100g deionized water, heat to 75℃ at 500rpm, and react for 40min to obtain PBA seed latex particles. T3. The polyurethane prepolymer obtained in T1 was dropped into the PBA seed latex particles obtained in T2, and 0.4g of ammonium persulfate was added. After reacting for 3 hours, PUR-ACR latex particles were obtained. T4. Mix 15g of ammonium persulfate and 3g of hydroxyethyl acrylate, then add the mixture to the PUR-ACR latex granules obtained in T3, and add 0.1g of ammonium persulfate. After reacting for 3 hours, cool to room temperature and discharge the material to obtain PUR-ACR-OH latex granules. T5. Add ethanol to the PUR-ACR-OH latex particles obtained in T4 and freeze for 30 hours to demulsify. Then dry them at 70°C for 16 hours to obtain the core-shell type PUR-ACR-OH toughening agent.

[0025] Example 1 S1. The raw materials are premixed and dried at 50°C for 2 hours. The raw materials include 100g of polycarbonate-type polyurethane elastomer prepared in Preparation Example 1.1, 5g of core-shell type PUR-ACR-OH toughening agent prepared in Preparation Example 2.1, 0.3g of antioxidant, and 0.7g of ultraviolet absorber. The antioxidants used in this example include antioxidant 168 and antioxidant 1010 in a mass ratio of 1:1. The ultraviolet absorbers used include ultraviolet absorber UV-400, ultraviolet absorber UV 284, and light stabilizer HS-112 in a mass ratio of 4.4:1.9:1. S2. The dried raw material is fed into a single-screw extruder for melting; S3. The molten mixture is formed through a die to obtain an extruded cast film; the temperature of the feeding section of the single screw extruder is 110℃, the temperature of barrel 1 is 115℃, the temperature of barrel 2 is 140℃, the temperature of barrel 3 is 150℃, the temperature of barrel 4 is 155℃, the temperature of barrel 5 is 160℃, the temperature of the filter screen is 160℃, and the screw speed is 28 rpm; S4. The cast film is cooled and its thickness is adjusted by using ceramic rollers and rubber rollers; S5. Trim and wind the film obtained in step S4 to obtain a PCU car cover with stretchability and a thickness of 0.1 mm.

[0026] Example 2 S1. The raw materials are premixed and dried at 50°C for 2 hours. The raw materials include 100g of polycarbonate-type polyurethane elastomer prepared in Preparation Example 1.1, 10g of core-shell type PUR-ACR-OH toughening agent prepared in Preparation Example 2.1, 0.4g of antioxidant, and 0.5g of ultraviolet absorber. The antioxidants used in this example include antioxidant 168 and antioxidant 1010 in a mass ratio of 1:1. The ultraviolet absorbers used include ultraviolet absorber UV-400, ultraviolet absorber UV 284, and light stabilizer HS-112 in a mass ratio of 4.4:1.9:1. S2. The dried raw material is fed into a single-screw extruder for melting; S3. The molten mixture is formed through a die to obtain an extruded cast film; the temperature of the feeding section of the single screw extruder is 110℃, the temperature of barrel 1 is 115℃, the temperature of barrel 2 is 140℃, the temperature of barrel 3 is 150℃, the temperature of barrel 4 is 155℃, the temperature of barrel 5 is 160℃, the temperature of the filter screen is 160℃, and the screw speed is 28 rpm; S4. The cast film is cooled and its thickness is adjusted by using ceramic rollers and rubber rollers; S5. Trim and wind the film obtained in step S4 to obtain a PCU car cover with stretchability and a thickness of 0.1 mm.

[0027] Example 3 S1. The raw materials are premixed and dried at 50°C for 2 hours. The raw materials include 100g of polycarbonate-type polyurethane elastomer prepared in Preparation Example 1.1, 15g of core-shell type PUR-ACR-OH toughening agent prepared in Preparation Example 2.1, 0.5g of antioxidant, and 0.3g of ultraviolet absorber. The antioxidants used in this example include antioxidant 168 and antioxidant 1010 in a mass ratio of 1:1. The ultraviolet absorbers used include ultraviolet absorber UV-400, ultraviolet absorber UV 284, and light stabilizer HS-112 in a mass ratio of 4.4:1.9:1. S2. The dried raw material is fed into a single-screw extruder for melting; S3. The molten mixture is formed through a die to obtain an extruded cast film; the temperature of the feeding section of the single screw extruder is 110℃, the temperature of barrel 1 is 115℃, the temperature of barrel 2 is 140℃, the temperature of barrel 3 is 150℃, the temperature of barrel 4 is 155℃, the temperature of barrel 5 is 160℃, the temperature of the filter screen is 160℃, and the screw speed is 28 rpm; S4. The cast film is cooled and its thickness is adjusted by using ceramic rollers and rubber rollers; S5. Trim and wind the film obtained in step S4 to obtain a PCU car cover with stretchability and a thickness of 0.1 mm.

[0028] Example 4 S1. The raw materials are premixed and dried at 53°C for 2.5 hours. The raw materials include 100g of polycarbonate-type polyurethane elastomer prepared in Preparation Example 1.2, 5g of core-shell type PUR-ACR-OH toughening agent prepared in Preparation Example 2.2, 0.3g of antioxidant, and 0.7g of ultraviolet absorber. The antioxidants used in this example include antioxidant 168 and antioxidant 1010 in a mass ratio of 1:1.5. The ultraviolet absorbers used include ultraviolet absorber UV-400, ultraviolet absorber UV284, and light stabilizer HS-112 in a mass ratio of 4.6:2:1. S2. The dried raw material is fed into a single-screw extruder for melting; S3. The molten mixture is formed through a die to obtain an extruded cast film; the temperature of the feeding section of the single screw extruder is 135℃, the temperature of barrel 1 is 120℃, the temperature of barrel 2 is 145℃, the temperature of barrel 3 is 155℃, the temperature of barrel 4 is 160℃, the temperature of barrel 5 is 165℃, the temperature of the filter screen is 165℃, and the screw speed is 30 rpm; S4. The cast film is cooled and its thickness is adjusted by using ceramic rollers and rubber rollers; S5. Trim and wind the film obtained in step S4 to obtain a PCU car cover with stretchability and a thickness of 0.1 mm.

[0029] Example 5 S1. The raw materials are premixed and dried at 55°C for 3 hours. The raw materials include 100g of polycarbonate-type polyurethane elastomer prepared in Preparation Example 1.3, 5g of core-shell type PUR-ACR-OH toughening agent prepared in Preparation Example 2.3, 0.3g of antioxidant, and 0.7g of ultraviolet absorber. The antioxidants used in this example include antioxidant 168 and antioxidant 1010 in a mass ratio of 1:2. The ultraviolet absorbers used include ultraviolet absorber UV-400, ultraviolet absorber UV 284, and light stabilizer HS-112 in a mass ratio of 4.8:2.1:1. S2. The dried raw material is fed into a single-screw extruder for melting; S3. The molten mixture is formed through a die to obtain an extruded cast film; the temperature of the feeding section of the single screw extruder is 160℃, the temperature of barrel 1 is 125℃, the temperature of barrel 2 is 150℃, the temperature of barrel 3 is 160℃, the temperature of barrel 4 is 165℃, the temperature of barrel 5 is 170℃, the temperature of the filter screen is 170℃, and the screw speed is 32 rpm; S4. The cast film is cooled and its thickness is adjusted by using ceramic rollers and rubber rollers; S5. Trim and wind the film obtained in step S4 to obtain a PCU car cover with stretchability and a thickness of 0.1 mm.

[0030] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the mass of the core-shell type PUR-ACR-OH toughening agent prepared by Preparation Example 2.1 in Comparative Example 1 is 1 g.

[0031] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the mass of the core-shell type PUR-ACR-OH toughening agent prepared by Preparation Example 2.1 in Comparative Example 2 is 20g.

[0032] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that an equal amount of commercially available polyurethane elastomer was used in Comparative Example 3 instead of the polycarbonate-type polyurethane elastomer prepared in Preparation Example 1.1 of this application.

[0033] Performance testing The elongation at break of the PCU car wrap films obtained in Examples 1-5 and Comparative Examples 1-3 was tested with reference to standard PT-6081G, and the results are shown in Table 1.

[0034] The tear strength of the PCU car wrap films obtained in Examples 1-5 and Comparative Examples 1-3 was tested according to standard GB / T 529, and the results are shown in Table 1.

[0035] Weather resistance test: The PCU car wrap films obtained in Examples 1-5 and Comparative Examples 1-3 were kept in an environment with a temperature of 80±2℃ for 24 hours and then allowed to recover at room temperature for 2 hours. Then the samples were kept in an environment with a temperature of -20±2℃ for 24 hours, and the car wrap films were observed to see if cracks, turbidity, bubbles, discoloration, etc. occurred. The results are shown in Table 1.

[0036] The specific test results are as follows: Table 1 Performance Test Results Elongation at break / % Tear strength (kN / m) Weather resistance Example 1 475 156 No change Example 2 496 165 No change Example 3 482 159 No change Example 4 486 162 No change Example 5 477 157 No change Comparative Example 1 389 103 Cracks and bubbles Comparative Example 2 366 92 No change Comparative Example 3 329 78 Cracks and bubbles As can be seen from the test results in Table 1, the PCU car cover provided in this application has high elongation at break and tear strength, indicating that the PCU car cover provided in this application has excellent mechanical properties and ductility. Moreover, after being treated alternately in environments of 80±2℃ and -20±2℃, there is no change in appearance, indicating that the PCU car cover provided in this application has excellent weather resistance.

[0037] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A stretchable PCU car cover, characterized in that: The raw materials, by weight, include 100 parts of polycarbonate-type polyurethane elastomer, 5-15 parts of toughening agent, 0.3-0.5 parts of antioxidant, and 0.3-0.7 parts of ultraviolet absorber; The toughening agent is a core-shell type PUR-ACR-OH toughening agent.

2. The PCU car cover with stretchability according to claim 1, characterized in that: The raw materials, by weight, include 100 parts of polycarbonate-type polyurethane elastomer, 10 parts of core-shell type PUR-ACR-OH toughening agent, 0.4 parts of antioxidant, and 0.5 parts of ultraviolet absorber.

3. A PCU car cover with stretchability according to claim 1, characterized in that: The polycarbonate-type polyurethane elastomer is prepared from the following raw materials in parts by weight: 50-60 parts polycarbonate diol, 250-300 parts tetrahydrofuran, 9-10.5 parts 4,4-diisocyanate dicyclohexylmethane, and 2.2-2.6 parts 1,4-butanediol.

4. A stretchable PCU car cover according to claim 3, characterized in that: The polycarbonate diol is prepared from the following raw materials in parts by weight: 20-40 parts diphenyl carbonate, 6.7-13.4 parts 1,8-octanediol, 9.2-18.4 parts 1,12-dodecanediol, and 0.004-0.008 parts catalyst.

5. A stretchable PCU car cover according to claim 4, characterized in that: The method for preparing the polycarbonate diol includes the following steps: Diphenyl carbonate, 1,8-octanediol, and 1,12-dodecanediol were mixed and heated to 160-200℃ under nitrogen protection. After the substances were completely melted, a catalyst was added, and the polycondensation reaction was carried out for 2-3 hours. Then, the mixture was distilled under reduced pressure for 30-60 minutes. After stopping the reaction, the product was cooled to room temperature and then dissolved in tetrahydrofuran. Methanol was added and stirred for 2-3 hours. The mixture was then vacuum filtered and the precipitate was collected. The precipitate was washed with methanol for 2-3 hours and then filtered again to collect the precipitate. After drying, polycarbonate diol was obtained.

6. A stretchable PCU car cover according to claim 3, characterized in that: The method for preparing the polycarbonate-type polyurethane elastomer includes the following steps: Polycarbonate diol was added to tetrahydrofuran and stirred at 100-150 rpm until completely dissolved. Then, under nitrogen protection, 4,4-diisocyanate dicyclohexylmethane was added dropwise at 60-70℃ and 400-500 rpm. After the addition was complete, 1,4-butanediol was added while stirring at 1000-1200 rpm. After reacting for 30-45 min, the reactants were placed at 50-60℃ for 12-16 h, then heated to 100-110℃ and placed for 2-3 h. Finally, the temperature was raised to 120-130℃ and aged for 24-28 h to obtain polycarbonate-type polyurethane elastomer.

7. A stretchable PCU car cover according to claim 1, characterized in that: The preparation method of the core-shell type PUR-ACR-OH toughening agent includes the following steps: T1. By weight, mix 4-8 parts of polypropylene glycol, 2-4 parts of hexamethylene diisocyanate, and 17.5-35 parts of butyl acrylate, and stir at room temperature for 1-2 hours; then add 0.5-1 parts of hydroxyethyl acrylate, and continue stirring at room temperature for 20-30 minutes to obtain a polyurethane prepolymer. T2. Add 2.5-5 parts butyl acrylate, 0.1-0.2 parts allyl methacrylate, 0.25-0.5 parts sodium dodecyl sulfate, 0.025-0.05 parts ammonium persulfate, and 0.025-0.05 parts sodium bicarbonate to 50-100 parts deionized water. Heat to 65-75℃ at 300-500 rpm and react for 30-40 minutes to obtain PBA seed latex particles. T3. The polyurethane prepolymer obtained in T1 is dropped into the PBA seed latex particles obtained in T2, and 0.3-0.4 parts of ammonium persulfate are added. After reacting for 2-3 hours, PUR-ACR latex particles are obtained. T4. Mix 7.5-15 parts of ammonium persulfate and 1.5-3 parts of hydroxyethyl acrylate, then add the mixture dropwise to the PUR-ACR latex particles obtained in T3, and add 0.05-0.1 parts of ammonium persulfate. After reacting for 2-3 hours, cool to room temperature, and discharge the material to obtain PUR-ACR-OH latex particles. T5. Add ethanol to the PUR-ACR-OH latex particles obtained in T4 and freeze for 24-30 hours to demulsify. Then dry in a forced-air dryer at 60-70℃ for 12-16 hours to obtain the core-shell type PUR-ACR-OH toughening agent.

8. A stretchable PCU car cover according to claim 1, characterized in that: The antioxidants include antioxidant 168 and antioxidant 1010 in a mass ratio of 1:1-2; The ultraviolet absorber is one or more of benzotriazole ultraviolet absorbers, triazine ultraviolet absorbers, and hindered amine light stabilizers.

9. A manufacturing process for a stretchable PCU car cover according to any one of claims 1-8, characterized in that: Includes the following steps: S1. Premix and dry the raw materials, which include polycarbonate-type polyurethane elastomer, toughening agent, antioxidant, and ultraviolet absorber; S2. The dried raw material is fed into a single-screw extruder for melting; S3. The molten mixture is formed through a die to obtain an extruded cast film; S4. The cast film is cooled and its thickness is adjusted by using ceramic rollers and rubber rollers; S5. Trim and wind the film obtained in step S4 to obtain a PCU car cover with stretchability.

10. The manufacturing process of a PCU car cover with extensibility according to claim 9, characterized in that: The temperature of the feeding section of the single-screw extruder described in S2 is 110-160℃, the temperature of barrel 1 is 115-125℃, the temperature of barrel 2 is 140-150℃, the temperature of barrel 3 is 150-160℃, the temperature of barrel 4 is 155-165℃, the temperature of barrel 5 is 160-170℃, the temperature of the filter screen is 160-170℃, and the screw speed is 28-32 rpm.