PVC transparent car cover film and preparation method thereof

Abstract

The invention discloses a PVC transparent car cover film and a preparation method thereof, and relates to the field of car cover films. The PVC transparent car cover film comprises a substrate, an adhesive layer, a base material, a self-repairing coating and a PET protective film which are sequentially arranged, the substrate is a PET release film, the adhesive layer is an acrylate pressure-sensitive adhesive, the self-repairing coating is a self-repairing coating, and the base material comprises the following raw materials in parts by weight: 80-100 parts of polyvinyl chloride resin; 12 to 15 parts of dioctyl phthalate; 5-8 parts of an auxiliary plasticizer; 3-7 parts of an impact modifier ACR; 2-5 parts of a barium-zinc stabilizer; 1-3 parts of rare earth nitrate; and 0.5-2 parts of BP modified hydrotalcite. The prepared vehicle cover film can overcome the defects that an existing polyvinyl chloride film is poor in tear resistance and prone to yellowing and the problem that the mechanical property and the self-repairing efficiency of a self-repairing coating cannot be considered at the same time, and the vehicle cover film has excellent mechanical strength, self-repairing efficiency and light transmittance.

Description

Technical Field

[0001] This invention relates to the field of car wrapping film, and in particular to a PVC transparent car wrapping film and its preparation method. Background Technology

[0002] With the improvement of people's living standards, cars have become a basic necessity for most ordinary families. Because cars are constantly exposed to the external environment, their original paint is easily damaged and requires frequent maintenance, hence the emergence of car wrapping film. Car wrapping film is a thin film applied to the car's paint surface to protect it or change its color. Applying car wrapping film isolates the car's paint from the air, providing protection against acid rain, oxidation, and scratches.

[0003] The car wrap film consists of a substrate, adhesive, base material, self-healing coating, and PET protective film. The substrate protects the adhesive layer from production to application; the adhesive connects the car wrap film to the car paint; the base material, as the main body of the car wrap film, provides a supporting framework; the self-healing coating is applied to the outermost layer and achieves functions such as brightening, stain resistance, hydrophobicity, and heat repair through a cross-linked structure; the PET protective film protects the self-healing coating from production to application.

[0004] Polyvinyl chloride (PVC) is a primary material for automotive film substrates, possessing excellent flexibility, durability, and transparency. However, PVC films themselves have low toughness, high brittleness, and poor tear resistance, and are prone to yellowing after long-term exposure, affecting the mechanical strength and light transmittance of the automotive film substrate. Furthermore, existing self-healing coatings for automotive films suffer from a trade-off between mechanical properties and self-healing efficiency. Therefore, it is necessary to improve existing automotive film products. Summary of the Invention

[0005] To address the shortcomings of existing polyvinyl chloride (PVC) films, such as poor tear resistance and susceptibility to yellowing, and the inability to simultaneously achieve optimal mechanical properties and self-healing efficiency in self-healing coatings, this application provides a transparent PVC car wrap film and its preparation method to improve the mechanical strength, self-healing efficiency, and light transmittance of the film.

[0006] The technical solution adopted in this application for a PVC transparent car wrap film and its preparation method is as follows: In a first aspect, this application provides a PVC transparent car wrap film, comprising a substrate, an adhesive layer, a base material, a self-healing coating, and a PET protective film arranged sequentially, wherein the substrate is a PET release film, the adhesive layer is an acrylic pressure-sensitive adhesive, the self-healing coating is a self-healing paint, and the base material comprises the following raw materials in parts by weight: 80-100 parts of polyvinyl chloride resin; 12-15 parts of dioctyl phthalate; 5-8 parts of auxiliary plasticizer; Impact modifier ACR 3-7 parts; 2-5 parts of barium zinc stabilizer; 1-3 parts rare earth nitrate; 0.5-2 parts of BP modified hydrotalcite; The rare earth nitrate is selected from one or more of lanthanum nitrate and yttrium nitrate; the auxiliary plasticizer is selected from one or more of polyester plasticizer and epoxidized soybean oil.

[0007] By adopting the above technical solution, the substrate is the core factor affecting the light transmittance and mechanical strength of PVC car wrap film. By changing the composition of the substrate, rare earth nitrate and BP modified hydrotalcite are added to the substrate raw materials, while maintaining high light transmittance, the toughness, mechanical strength and aging resistance of PVC film are improved, and it is not easy to yellow after long-term use.

[0008] The addition of rare earth nitrates can form ligands and chelates with the raw materials in the system, improving the compatibility and interaction of components. The complexation bonds of rare earth elements are beneficial to increasing the crosslinking strength of the PVC polymer, thereby enhancing the mechanical properties of the PVC film. Simultaneously, the PVC film exhibits high transparency and good light transmittance. PVC film preparation requires high-temperature mixing and calendering. BP-modified hydrotalcite, by intercalating the ultraviolet absorber BP into the hydrotalcite, can solve the problems of BP's poor thermal stability and migration within the PVC polymer. Furthermore, BP-modified hydrotalcite can act as a heat stabilizer, improving the aging resistance of the PVC film and reducing yellowing after long-term use.

[0009] Optionally, the BP-modified hydrotalcite is prepared by the following steps: Preparation of hydrotalcite precursor: Weigh zinc nitrate hexahydrate and aluminum nitrate nonahydrate, and prepare a mixed salt solution with a Zn / Al molar ratio of 2 using deionized water. Add urea to the mixed solution, with a molar ratio of urea to nitrate ions of (3.5-4):1. Place the above solution in an oil bath and stir vigorously at 105-120℃ for 10-12 h. Cool to 80-85℃ and statically crystallize for 12 h. Wash and dry the crystallized product to obtain zinc-aluminum hydrotalcite. Calcinate the zinc-aluminum hydrotalcite at 500-600℃ for 4-6 h to obtain the calcined hydrotalcite product. Preparation of BP-modified hydrotalcite: The calcined hydrotalcite product was weighed and ultrasonically dispersed in deionized water to obtain solution A. 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid was weighed and added to deionized water. The pH was adjusted to 7 with NaOH solution to prepare solution B. The mass ratio of the calcined hydrotalcite product to 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid was (1.2-1.5):1. Solution B was added to solution A under nitrogen protection, and the mixture was vigorously stirred in an oil bath at 100-110℃ for 24 hours. After filtration and drying, BP-modified hydrotalcite was obtained.

[0010] By adopting the above technical solution, BP is inserted into the interlayer of hydrotalcite through calcination reduction. BP and hydrotalcite interact through hydrogen bonds to achieve a stable bond. At the same time, hydrotalcite stabilizes the UV absorber BP at high temperatures, enabling the PVC film to absorb UV light well and improving the discoloration phenomenon of PVC film after aging.

[0011] Optionally, the polyvinyl chloride resin is selected as lanthanum acrylate modified polyvinyl chloride resin, which is prepared by the following steps: Place 3-6 parts of acrylic acid and 5-8 parts of lanthanum oxide into a reactor and react at a constant temperature of 60-65℃ for 30-50 min. Then raise the temperature to 85-90℃ and react for 2-2.5 h. After cooling, add ethanol to the solution after the reaction to precipitate solid powder. Wash and dry the solid powder to obtain lanthanum acrylate. Dissolve 600-800 parts of polyvinyl chloride resin in tetrahydrofuran and stir until homogeneous to obtain a stirring solution. Mix lanthanum acrylate with the stirring solution and heat to 58-62℃. Dissolve 2-5 parts of benzoyl peroxide in tetrahydrofuran to obtain a dropping solution. Add the dropping solution to the above reaction solution and react at a constant temperature for 8-9 hours to obtain the product. The obtained product was extracted with toluene as solvent in a Soxhlet extractor for 48 hours, then vacuum dried and pulverized into powder to obtain lanthanum acrylate modified polyvinyl chloride resin.

[0012] By adopting the above technical solution, lanthanum acrylate is used to graft and modify PVC. Through crosslinking with PVC resin, the toughness and thermal stability of PVC resin are improved. Lanthanum acrylate can also act as an absorbent of HCl in PVC, replacing unstable chlorine, thereby improving the performance of PVC film.

[0013] Optionally, the polyvinyl chloride resin is selected from SG-5 type polyvinyl chloride resin with a degree of polymerization of 800-1500.

[0014] Optionally, the self-healing coating comprises the following raw materials in parts by weight: 35-40 parts of diol; 12-17 parts of isophorone diisocyanate; 0.01-0.03 parts of dibutylene dilaurate; 1-1.5 parts of 2,5-furandiethanol; 1-1.5 parts of 4,4'-dihydroxydiphenyl sulfide; 1.5-2 parts of bismaleimide; Additives 3-6 parts.

[0015] By adopting the above technical solution, disulfide bonds and DA crosslinking networks were selected as self-healing materials in the self-healing coating. A dual-adjustment network was built by setting the ratio, which ensured that the polyurethane material had both high mechanical strength and high self-healing efficiency, enabling the car film to self-heal at lower temperatures.

[0016] Optionally, the diol is a mixture of polycaprolactone diol and polytetrahydrofuran in a weight ratio of (1.2-1.4):1.

[0017] By adopting the above technical solution, the diol is a compound of polyester diol and polyether diol in a specific ratio. By selecting the polyol, the soft segment properties of polyurethane are changed, so that the prepared self-healing coating has good hydrophobicity and thermal stability. At the same time, the self-healing coating has excellent mechanical properties, with good tensile strength and elasticity.

[0018] Optionally, the additive may be one or more of leveling agents, defoamers, wetting agents, and anti-sagging additives.

[0019] Optionally, the self-healing coating is prepared according to the following steps: Isophorone diisocyanate and dibutylene dilaurate were added to a flask and mixed. A mixture of diol and N,N-dimethyldiamide was added dropwise to the flask. The mixture was heated to 60-65℃ and reacted for 2-2.5 hours to obtain the prepolymer. Add 2,5-furandiethanol and 4,4'-dihydroxydiphenyl sulfide to the prepolymer solution, and perform chain extension reaction at 80-83℃ for 6-7 hours. Cool the product to room temperature, add bismaleimide and additives, stir for 30-50 minutes to disperse evenly, pour the evenly mixed solution into a PTFE mold, and place the mold in an oven at 65-68℃ for 48-52 hours to obtain the self-healing coating.

[0020] Secondly, this application discloses a method for preparing a PVC transparent car wrap film, comprising the following steps: PET release film is selected as the substrate, and acrylic pressure-sensitive adhesive is coated on the substrate to form an adhesive layer; Weigh out polyvinyl chloride resin, dioctyl phthalate, auxiliary plasticizer, impact modifier ACR, barium zinc stabilizer, rare earth nitrate and BP modified hydrotalcite and mix them evenly. Put them into a compounding extruder and mix them at 130-140℃. Calender the compounded material using a five-roll calender. After cooling and drying, obtain PVC film. Coat the PVC film onto the surface of the adhesive layer away from the PET release film to form a substrate. A self-healing coating is obtained by applying the self-healing coating onto the surface of the substrate away from the adhesive layer. A PET protective film is applied to the side of the self-healing coating away from the substrate to obtain a PVC transparent car wrap film.

[0021] By adopting the above technical solution, PVC transparent car wrap film can be prepared through the combination of multiple layers, and the preparation process is simple.

[0022] In summary, this application has at least one of the following beneficial effects: In PVC car wrap film, the substrate is the core factor affecting the light transmittance and mechanical strength of the film. By changing the composition of the substrate, rare earth nitrate and BP modified hydrotalcite are added to the substrate raw materials, while maintaining high light transmittance, the toughness, mechanical strength and aging resistance of the PVC film are improved, and it is not easy to yellow after long-term use.

[0023] The addition of rare earth nitrates can form ligands and chelates with the raw materials in the system, improving the compatibility and interaction of components. The complexation bonds of rare earth elements are beneficial to increasing the crosslinking strength of the PVC polymer, thereby enhancing the mechanical properties of the PVC film. Simultaneously, the PVC film exhibits high transparency and good light transmittance. PVC film preparation requires high-temperature mixing and calendering. BP-modified hydrotalcite, by intercalating the ultraviolet absorber BP into the hydrotalcite, can solve the problems of BP's poor thermal stability and migration within the PVC polymer. Furthermore, BP-modified hydrotalcite can act as a heat stabilizer, improving the aging resistance of the PVC film and reducing yellowing after long-term use. Attached Figure Description

[0024] Figure 1 This application describes a method for preparing a PVC transparent car wrap film.

[0025] Explanation of reference numerals in the attached figures: 1. Substrate; 2. Adhesive layer; 3. Substrate material; 4. Self-healing coating; 5. PET protective film. Detailed Implementation

[0026] The present application will be further described in detail below with reference to Examples 1-9 and Comparative Examples 1-2.

[0027] The polyvinyl chloride resin used was SG-5 type PVC resin with a degree of polymerization of 1500, which was purchased from Hubei Xindongyi New Material Technology Co., Ltd. Dioctyl phthalate was purchased from Changzhou Senlang Chemical Co., Ltd. The polyester plasticizer used was a polyester plasticizer with a molecular weight of 3000 and a model number of W-2370, which was purchased from DIC Corporation. The epoxidized soybean oil was purchased from Changzhou Senlang Chemical Co., Ltd. The impact modifier ACR was purchased from Hubei Xindongyi New Material Technology Co., Ltd., and its brand name is ACR-401. The barium zinc stabilizer, brand name BZ-424PF, was purchased from Nantong Aidewang Chemical Co., Ltd. Lanthanum nitrate and yttrium nitrate were both purchased from Jining Maikerui Rare Earth Co., Ltd. 2-Hydroxy-4-methoxybenzophenone-5-sulfonic acid was purchased from Wuhan Shuer Biotechnology Co., Ltd., CAS No. 4065-45-6; Polycaprolactone diol with a molecular weight of 2000 and CAS number 36890-68-3 was selected and purchased from Hubei Wanbikete Biomedical Co., Ltd. The polytetrahydrofuran used was a polytetrahydrofuran with a molecular weight of 2000 and CAS number 25190-06-1, which was purchased from Shandong Yuxuan Chemical Products Co., Ltd. 2,5-Furfural was purchased from Wuhan Smike Biotechnology Co., Ltd., CAS No. 1883-75-6; 4,4'-Dihydroxydiphenyl sulfide was purchased from Hubei Watson Chemical Technology Co., Ltd., CAS No. 2664-63-3; The bismaleimide was purchased from Wuhan Chengtian Fine Chemical Co., Ltd., CAS No. 13676-54-5. Preparation Example

[0028] Preparation Example 1 Preparation of BP-modified hydrotalcite Preparation of hydrotalcite precursor: Weigh zinc nitrate hexahydrate and aluminum nitrate nonahydrate, and prepare a mixed salt solution with a Zn / Al molar ratio of 2 using deionized water. Add urea to the mixed solution, with a molar ratio of urea to nitrate ions of 3.5:1. Place the above solution in an oil bath and stir vigorously at 105℃ for 10 h. Cool to 80℃ and statically crystallize for 12 h. Then wash with deionized water and filter. Dry at 75℃ to obtain zinc-aluminum hydrotalcite. Calcine the zinc-aluminum hydrotalcite at 500℃ for 4 h to obtain the calcined hydrotalcite product. Preparation of BP-modified hydrotalcite: The calcined hydrotalcite product was weighed and ultrasonically dispersed in deionized water to obtain solution A. 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid was weighed and added to deionized water. NaOH solution was added under stirring to adjust the pH to 7 to prepare solution B. The mass ratio of the calcined hydrotalcite product to 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid was 1.2:1. Solution B was added to solution A under nitrogen protection and vigorously stirred in an oil bath at 100°C for 24 hours. Then, the mixture was washed with deionized water, filtered, and dried at 75°C to obtain BP-modified hydrotalcite.

[0029] Preparation Example 2 Preparation of BP-modified hydrotalcite Preparation of hydrotalcite precursor: Weigh zinc nitrate hexahydrate and aluminum nitrate nonahydrate, and prepare a mixed salt solution with a Zn / Al molar ratio of 2 using deionized water. Add urea to the mixed solution, with a molar ratio of urea to nitrate ions of 4:1. Place the above solution in an oil bath and stir vigorously at 120°C for 12 hours. Cool to 85°C and statically crystallize for 12 hours. Then wash and filter with deionized water, and dry at 80°C to obtain zinc-aluminum hydrotalcite. Calcinate the zinc-aluminum hydrotalcite at 600°C for 6 hours to obtain the calcined hydrotalcite product. Preparation of BP-modified hydrotalcite: The calcined hydrotalcite product was weighed and ultrasonically dispersed in deionized water to obtain solution A. 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid was weighed and added to deionized water. NaOH solution was added under stirring to adjust the pH to 7 to prepare solution B. The mass ratio of the calcined hydrotalcite product to 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid was 1.5:1. Solution B was added to solution A under nitrogen protection and vigorously stirred in an oil bath at 110°C for 24 hours. Then, the mixture was washed with deionized water, filtered, and dried at 80°C to obtain BP-modified hydrotalcite.

[0030] Preparation Example 3 Preparation of lanthanum acrylate modified polyvinyl chloride resin: Three parts of acrylic acid and five parts of lanthanum oxide were placed in a reactor and reacted at a constant temperature of 60°C for 30 minutes. The temperature was then raised to 85°C and reacted for 2 hours. After cooling, ethanol was added to the reaction solution to precipitate solid powder. The solid powder was washed multiple times with ethanol and dried in a vacuum oven at 50°C to obtain lanthanum acrylate. 600 parts of polyvinyl chloride resin were dissolved in 900 parts of tetrahydrofuran and stirred evenly to obtain a stirring solution. Lanthanum acrylate was mixed with the stirring solution and heated to 58°C. 2 parts of benzoyl peroxide were dissolved in 10 parts of tetrahydrofuran to obtain a dropping solution. The dropping solution was added dropwise to the above reaction solution and reacted at a constant temperature for 8 hours to obtain the product. The obtained product was extracted with toluene as solvent in a Soxhlet extractor for 48 hours, then vacuum dried and pulverized into powder to obtain lanthanum acrylate modified polyvinyl chloride resin.

[0031] Preparation Example 4 Preparation of lanthanum acrylate modified polyvinyl chloride resin: Six parts of acrylic acid and eight parts of lanthanum oxide were placed in a reactor and reacted at a constant temperature of 65°C for 50 min. The temperature was then raised to 90°C and reacted for 2.5 h. After cooling, ethanol was added to the reaction solution to precipitate solid powder. The solid powder was washed multiple times with ethanol and dried in a vacuum oven at 55°C to obtain lanthanum acrylate. Dissolve 800 parts of polyvinyl chloride resin in 1500 parts of tetrahydrofuran and stir until homogeneous to obtain a stirring solution. Mix lanthanum acrylate with the stirring solution and heat to 62°C. Dissolve 5 parts of benzoyl peroxide in 20 parts of tetrahydrofuran to obtain a dropping solution. Add the dropping solution to the above reaction solution and react at a constant temperature for 9 hours to obtain the product. The obtained product was extracted with toluene as solvent in a Soxhlet extractor for 48 hours, then vacuum dried and pulverized into powder to obtain lanthanum acrylate modified polyvinyl chloride resin. Example

[0032] Example 1 A PVC transparent car wrap film includes a substrate, an adhesive layer, a base material, a self-healing coating, and a PET protective film arranged sequentially. Specifically, the substrate is a PET release film with a thickness of 20 μm, the adhesive layer is an acrylic pressure-sensitive adhesive with a thickness of 15 μm, the base material is a PVC film with a thickness of 50 μm, the self-healing coating is a self-healing coating with a thickness of 15 μm, and the PET protective film has a thickness of 25 μm.

[0033] The substrate comprises the following raw materials in parts by weight: 80 parts of polyvinyl chloride resin; 12 parts of dioctyl phthalate; 5 parts of auxiliary plasticizer, selected from polyester plasticizer; 3 parts of impact modifier ACR; Two parts of barium zinc stabilizer; one part of rare earth nitrate, using lanthanum nitrate; 0.5 parts of BP-modified hydrotalcite were used, specifically the BP-modified hydrotalcite prepared in Preparation Example 1.

[0034] The substrate is prepared by the following steps: Weigh out polyvinyl chloride resin, dioctyl phthalate, auxiliary plasticizer, impact modifier ACR, barium zinc stabilizer, rare earth nitrate and BP modified hydrotalcite, mix them evenly, and put them into a compounding extruder for compounding at 130°C. The compounded material is then calendered using a five-roll calender to obtain a film, where the temperature of roll 1 is 190°C, roll 2 is 200°C, roll 3 is 190°C, roll 4 is 185°C, and roll 5 is 180°C. The film is cooled with 40°C cooling water and dried to obtain a PVC film, which is used as the substrate.

[0035] Self-healing coatings consist of the following raw materials in parts by weight: 35 parts of diol, of which 19.1 parts of polycaprolactone diol and 15.9 parts of polytetrahydrofuran were selected; 12 parts of isophorone diisocyanate; 0.01 parts of dibutyltin dilaurate; 1 part of 2,5-furandiethanol; 1 part of 4,4'-dihydroxydiphenyl sulfide; 1.5 parts of bismaleimide; Add 3 parts of additives, specifically a leveling agent.

[0036] Self-healing coatings are prepared through the following steps: Isophorone diisocyanate and dibutylene dilaurate were added to a flask and mixed. A mixture of diol and 50 parts of N,N-dimethyldiamide was added dropwise to the flask. The mixture was heated to 60°C and reacted for 2 hours to obtain the prepolymer. Add 2,5-furandiethanol and 4,4'-dihydroxydiphenyl sulfide to the prepolymer solution, and perform chain extension reaction at 80°C for 6 hours. Cool the product to room temperature, add bismaleimide and additives, stir for 30 minutes to disperse evenly, pour the evenly mixed solution into a PTFE mold, and place the mold in an oven at 65°C for 48 hours to obtain the self-healing coating.

[0037] The preparation method of PVC transparent car wrap film includes the following steps: PET release film is selected as the substrate, and acrylic pressure-sensitive adhesive is coated on the substrate to form an adhesive layer; A PVC film is coated onto the surface of the adhesive layer away from the PET release film to form a substrate; A self-healing coating is obtained by applying the self-healing coating onto the surface of the substrate away from the adhesive layer. A PET protective film is applied to the side of the self-healing coating away from the substrate to obtain a PVC transparent car wrap film.

[0038] Example 2 A PVC transparent car wrap film includes a substrate, an adhesive layer, a base material, a self-healing coating, and a PET protective film arranged sequentially. Specifically, the substrate is a PET release film with a thickness of 20 μm, the adhesive layer is an acrylic pressure-sensitive adhesive with a thickness of 15 μm, the base material is a PVC film with a thickness of 50 μm, the self-healing coating is a self-healing coating with a thickness of 15 μm, and the PET protective film has a thickness of 25 μm.

[0039] The substrate comprises the following raw materials in parts by weight: 100 parts polyvinyl chloride resin; 15 parts dioctyl phthalate; 8 parts of auxiliary plasticizer, made from epoxidized soybean oil; 7 parts of impact modifier ACR; 5 parts barium zinc stabilizer; 3 parts rare earth nitrate, yttrium nitrate is selected; Two portions of BP-modified hydrotalcite were used, specifically the BP-modified hydrotalcite prepared in Preparation Example 2.

[0040] The substrate is prepared by the following steps: Weigh out polyvinyl chloride resin, dioctyl phthalate, auxiliary plasticizer, impact modifier ACR, barium zinc stabilizer, rare earth nitrate and BP modified hydrotalcite, mix them evenly, and put them into a compounding extruder for compounding at 140°C. The compounded material is then calendered using a five-roll calender to obtain a film, where the temperature of roll 1 is 195°C, roll 2 is 210°C, roll 3 is 200°C, roll 4 is 195°C, and roll 5 is 185°C. The film is cooled with 40°C cooling water and dried to obtain a PVC film, which is used as the substrate.

[0041] Self-healing coatings consist of the following raw materials in parts by weight: 40 parts of diol, of which 23.3 parts of polycaprolactone diol and 16.7 parts of polytetrahydrofuran were selected; 17 parts of isophorone diisocyanate; 0.03 parts of dibutyltin dilaurate; 1.5 parts of 2,5-furandiethanol 1.5 parts of 4,4'-dihydroxydiphenyl sulfide; Two parts of bismaleimide; The additive consists of 6 parts, specifically 4 parts wetting agent and 2 parts defoamer.

[0042] Self-healing coatings are prepared through the following steps: Isophorone diisocyanate and dibutylene dilaurate were added to a flask and mixed. A mixture of diol and 65 parts of N,N-dimethyldiamide was added dropwise to the flask. The mixture was heated to 65°C and reacted for 2.5 h to obtain the prepolymer. 2,5-furandiethanol and 4,4'-dihydroxydiphenyl sulfide were added to the prepolymer solution, and the chain extension reaction was carried out at 83°C for 7 hours. The product was cooled to room temperature, and bismaleimide and additives were added. The mixture was stirred for 50 minutes to disperse evenly. The evenly mixed solution was poured into a PTFE mold, and the mold was placed in an oven at 68°C for 52 hours to obtain a self-healing coating.

[0043] The preparation method of PVC transparent car wrap film includes the following steps: PET release film is selected as the substrate, and acrylic pressure-sensitive adhesive is coated on the substrate to form an adhesive layer; A PVC film is coated onto the surface of the adhesive layer away from the PET release film to form a substrate; A self-healing coating is obtained by applying the self-healing coating onto the surface of the substrate away from the adhesive layer. A PET protective film is applied to the side of the self-healing coating away from the substrate to obtain a PVC transparent car wrap film.

[0044] Examples 3-7 The difference between Examples 3-7 and Example 1 is that the raw materials of the substrate and the self-healing coating are different from those in Example 1.

[0045] Components Example 3 Example 4 Example 5 Example 6 Example 7 Polyvinyl chloride resin 88 80, Preparation Example 3 80, Preparation Example 4 80 80 Dioctyl phthalate 14 12 12 12 12 Plasticizer 7 5 5 5 5 Impact modifier ACR 5 3 3 3 3 Zinc-barium stabilizer 3 2 2 2 2 Rare earth nitrate 2. Lanthanum nitrate 1. Lanthanum nitrate 1. Lanthanum nitrate 1. Lanthanum nitrate 1. Lanthanum nitrate BP modified hydrotalcite 1.2, Preparation Example 2 0.5, Preparation Example 1 0.5, Preparation Example 1 0.5, Preparation Example 1 0.5, Preparation Example 1 Components Example 3 Example 4 Example 5 Example 6 Example 7 Polycaprolactone diol 21.5 19.1 19.1 0 35 Polytetrahydrofuran 16.5 15.9 15.9 35 0 Isophorone diisocyanate 14 12 12 12 12 dibutylene dilaurate 0.02 0.01 0.01 0.01 0.01 2,5-Furfural 1.2 2 2 2 2 4,4'-Dihydroxydiphenyl sulfide 1.3 1 1 1 1 bismaleimide 1.8 1.5 1.5 1.5 1.5 Additives 4. Wetting agent 3. Leveling agent 3. Leveling agent 3. Leveling agent 3. Leveling agent Example 8 The difference between Example 8 and Example 1 is that the raw materials of the self-healing coating of the PVC transparent car wrap film are different.

[0046] In this embodiment, 1,4-butanediol is used in equal parts by mass to replace 4,4'-dihydroxydiphenyl sulfide in the raw materials of the self-healing coating.

[0047] Example 9 The difference between Example 9 and Example 1 is that the raw materials of the self-healing coating of the PVC transparent car wrap film are different.

[0048] In this embodiment, 1,4-butanediol was used in equal parts by mass to replace 2,5-furandiethanol in the raw materials of the self-healing coating, and no bismaleimide was added to the raw materials. Comparative Example

[0049] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the raw materials of the substrate of the PVC transparent car wrap film are different.

[0050] In this comparative example, no rare earth olefins were added to the raw materials of the substrate.

[0051] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the raw materials of the substrate of the PVC transparent car wrap film are different.

[0052] In this comparative example, BP (2-hydroxy-4-methoxybenzophenone-5-sulfonic acid) was used in equal parts by weight instead of BP-modified hydrotalcite in the raw materials of the substrate. Performance testing

[0053] The following performance tests were conducted on the PVC film substrates, self-healing coatings, and car wraps prepared in the various embodiments and preparation examples.

[0054] The light transmittance of PVC film was tested according to GB / T 2410-2008 "Determination of light transmittance and haze of transparent plastics".

[0055] Tensile properties of PVC film: Tested according to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", with a sample width of 25 mm, a length of 150 mm, a distance of 100 mm between clamps, and a tensile rate of 300 mm / min.

[0056] Yellowing resistance of PVC film: After irradiating PVC film samples with ultraviolet light in a UVA aging chamber, the color change rate ΔE of the samples was calculated after 672 hours.

[0057] Mechanical properties of self-healing coatings: Tested according to GB / T 1040.3-2006 "Test conditions for tensile properties of plastic films" using a universal tensile testing machine.

[0058] Self-healing efficiency of self-healing coating: The self-healing coating was applied to a transparent PET film with a coating thickness of 15μm. After drying, a self-healing film was formed. At 60℃, a scratch with a depth of 0.005mm was made on each group of self-healing films using a nano-scratch instrument, and the time required for recovery was recorded.

[0059] Sample Light transmittance (%) PVC film tensile strength (MPa) Color change rate ΔE Tensile strength (MPa) of self-healing coating Self-repair time (s) Example 1 92.2 38.8 2.68 28.7 21 Example 2 92.8 39.2 2.65 30.2 18 Example 3 92.5 38.6 2.71 31.6 20 Example 4 93.5 41.7 0.91 28.7 21 Example 5 93.8 42.1 0.87 28.7 21 Example 6 92.2 38.8 2.68 26.5 27 Example 7 92.2 38.8 2.68 25.4 26 Example 8 92.2 38.8 2.68 13.8 35 Example 9 92.2 38.8 2.68 10.3 38 Comparative Example 1 92.1 30.3 7.19 28.7 21 Comparative Example 2 91.3 36.5 13.75 28.7 21 According to the data in the table, this application modifies the substrate and self-healing coating of the car wrap film. By adding rare earth nitrates to the substrate raw material of the car wrap film to coordinate and complex the polyvinyl chloride resin system, the degree of cross-linking is increased, thus improving the tensile strength of the polyvinyl chloride film. Simultaneously, the antioxidant and UV-resistant properties of rare earth elements improve the aging resistance and anti-yellowing properties of the substrate, which helps maintain the light transmittance of the substrate. As a UV absorber, BP exhibits migration problems when used in the polyvinyl chloride resin system for a long time. Intercalation to obtain BP-modified hydrotalcite can improve the thermal stability of BP, solve the migration problem, and alleviate the decline in the mechanical properties of the PVC film material by slowing down the aging and surface degradation of the PVC film.

[0060] In self-healing materials, disulfide bonds and DA crosslinking networks are used as dual-regulating self-healing networks. The self-healing efficiency of the coating is improved by combining the two self-healing systems. At the same time, through the combination, the presence of the DA covalent crosslinking network increases the stability of the polyurethane polymer network. The disulfide bonds are locked in the hard segment structure in the polyurethane network, which can maintain good mechanical properties at room temperature. When repair is required, the disulfide bonds and DA crosslinking network can work together to improve the mechanical properties of the material.

[0061] 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 specific 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 PVC transparent car wrap film, characterized in that: The material comprises, in sequence, a substrate, an adhesive layer, a base material, a self-healing coating, and a PET protective film, wherein the substrate is a PET release film, the adhesive layer is an acrylic pressure-sensitive adhesive, the self-healing coating is a self-healing paint, and the base material comprises the following raw materials in parts by weight: 80-100 parts of polyvinyl chloride resin; 12-15 parts of dioctyl phthalate; 5-8 parts of auxiliary plasticizer; Impact modifier ACR 3-7 parts; 2-5 parts of barium zinc stabilizer; 1-3 parts rare earth nitrate; 0.5-2 parts of BP modified hydrotalcite; The rare earth nitrate is selected from one or more of lanthanum nitrate and yttrium nitrate; the auxiliary plasticizer is selected from one or more of polyester plasticizer and epoxidized soybean oil.

2. The PVC transparent car wrap film according to claim 1, characterized in that: The BP-modified hydrotalcite is prepared through the following steps: Preparation of hydrotalcite precursor: Weigh zinc nitrate hexahydrate and aluminum nitrate nonahydrate, and prepare a mixed salt solution with a Zn / Al molar ratio of 2 using deionized water. Add urea to the mixed solution, with a molar ratio of urea to nitrate ions of (3.5-4):

1. Place the above solution in an oil bath and stir vigorously at 105-120℃ for 10-12 h. Cool to 80-85℃ and statically crystallize for 12 h. Wash and dry the crystallized product to obtain zinc-aluminum hydrotalcite. Calcinate the zinc-aluminum hydrotalcite at 500-600℃ for 4-6 h to obtain the calcined hydrotalcite product. Preparation of BP-modified hydrotalcite: The calcined hydrotalcite product was weighed and ultrasonically dispersed in deionized water to obtain solution A. 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid was weighed and added to deionized water. The pH was adjusted to 7 with NaOH solution to prepare solution B. The mass ratio of the calcined hydrotalcite product to 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid was (1.2-1.5):

1. Solution B was added to solution A under nitrogen protection, and the mixture was vigorously stirred in an oil bath at 100-110℃ for 24 hours. After filtration and drying, BP-modified hydrotalcite was obtained.

3. The PVC transparent car wrap film according to claim 1, characterized in that: The polyvinyl chloride resin is selected as lanthanum acrylate modified polyvinyl chloride resin, which is prepared by the following steps: Place 3-6 parts of acrylic acid and 5-8 parts of lanthanum oxide into a reactor and react at a constant temperature of 60-65℃ for 30-50 min. Then raise the temperature to 85-90℃ and react for 2-2.5 h. After cooling, add ethanol to the solution after the reaction to precipitate solid powder. Wash and dry the solid powder to obtain lanthanum acrylate. Dissolve 600-800 parts of polyvinyl chloride resin in tetrahydrofuran and stir until homogeneous to obtain a stirring solution. Mix lanthanum acrylate with the stirring solution and heat to 58-62℃. Dissolve 2-5 parts of benzoyl peroxide in tetrahydrofuran to obtain a dropping solution. Add the dropping solution to the above reaction solution and react at a constant temperature for 8-9 hours to obtain the product. The obtained product was extracted with toluene as solvent in a Soxhlet extractor for 48 hours, then vacuum dried and pulverized into powder to obtain lanthanum acrylate modified polyvinyl chloride resin.

4. The PVC transparent car wrap film according to claim 3, characterized in that: The polyvinyl chloride resin used is SG-5 type polyvinyl chloride resin with a degree of polymerization of 800-1500.

5. The PVC transparent car wrap film according to claim 1, characterized in that: The self-healing coating comprises the following raw materials in parts by weight: 35-40 parts of diol; 12-17 parts of isophorone diisocyanate; 0.01-0.03 parts of dibutylene dilaurate; 1-1.5 parts of 2,5-furandiethanol; 1-1.5 parts of 4,4'-dihydroxydiphenyl sulfide; 1.5-2 parts of bismaleimide; Additives 3-6 parts.

6. The PVC transparent car wrap film according to claim 5, characterized in that: The diol is selected from a mixture of polycaprolactone diol and polytetrahydrofuran in a weight ratio of (1.2-1.4):

1.

7. The PVC transparent car wrap film according to claim 5, characterized in that: The additives are selected from one or more of the following: leveling agents, defoamers, wetting agents, and anti-sagging additives.

8. The PVC transparent car wrap film according to claim 5, characterized in that: The self-healing coating is prepared according to the following steps: Isophorone diisocyanate and dibutylene dilaurate were added to a flask and mixed. A mixture of diol and N,N-dimethyldiamide was added dropwise to the flask. The mixture was heated to 60-65℃ and reacted for 2-2.5 hours to obtain the prepolymer. Add 2,5-furandiethanol and 4,4'-dihydroxydiphenyl sulfide to the prepolymer solution, and perform chain extension reaction at 80-83℃ for 6-7 hours. Cool the product to room temperature, add bismaleimide and additives, stir for 30-50 minutes to disperse evenly, pour the evenly mixed solution into a PTFE mold, and place the mold in an oven at 65-68℃ for 48-52 hours to obtain the self-healing coating.

9. A method for preparing a PVC transparent car wrap film according to any one of claims 1-8, characterized in that, Includes the following steps: PET release film is selected as the substrate, and acrylic pressure-sensitive adhesive is coated on the substrate to form an adhesive layer; Weigh out polyvinyl chloride resin, dioctyl phthalate, auxiliary plasticizer, impact modifier ACR, barium zinc stabilizer, rare earth nitrate and BP modified hydrotalcite and mix them evenly. Put them into a compounding extruder and mix them at 130-140℃. Calender the compounded material using a five-roll calender. After cooling and drying, obtain PVC film. Coat the PVC film onto the surface of the adhesive layer away from the PET release film to form a substrate. A self-healing coating is obtained by applying the self-healing coating onto the surface of the substrate away from the adhesive layer. A PET protective film is applied to the side of the self-healing coating away from the substrate to obtain a PVC transparent car wrap film.

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