Acrylic acid pressure-sensitive adhesive for PVC (Polyvinyl Chloride) car cover film and preparation method thereof

Abstract

The invention relates to an acrylic pressure-sensitive adhesive for a PVC (polyvinyl chloride) car cover film and a preparation method thereof, and belongs to the technical field of high polymer materials. The pressure-sensitive adhesive comprises the following raw materials: a soft monomer, a hard monomer, a hydroxyl acrylic monomer, an initiator, anhydride, a cross-linking agent and a solvent. The preparation method is a semi-continuous titration method, and comprises the key steps of firstly carrying out pre-reaction on anhydride and part of the cross-linking agent, and then dropwise adding a monomer and an initiator step by step for copolymerization. According to the pressure-sensitive adhesive disclosed by the invention, acid anhydride is introduced and has a synergistic effect with a hydroxyl monomer and a cross-linking agent in a polymerization process, and a strong-polarity and compact cross-linked structure is constructed on a polymer chain, so that the plasticizer resistance of the pressure-sensitive adhesive is improved, and migration and precipitation of a plasticizer in a PVC (Polyvinyl Chloride) film are effectively resisted; and the pressure-sensitive adhesive is endowed with excellent stripping force, annular initial adhesion, heat resistance and UV aging resistance, and the problems of adhesive residue, shadow, excessive adhesive and the like which are easily generated when the traditional pressure-sensitive adhesive is used for the PVC automobile cover film are solved.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and relates to an acrylic pressure-sensitive adhesive for PVC car wrap film and its preparation method. Background Technology

[0002] Automotive paint protection film, also known as car wrap film, is a protective film applied to the car body to protect the paint. As an important product for protecting automotive paint, car wrap film is widely used in the automotive detailing and maintenance industry. It effectively reduces or prevents damage to the original paint from physical scratches, sunlight, exhaust fumes, and corrosive substances, while being easy to repair and having low replacement costs. The base film materials for car wrap film are mainly polyvinyl chloride (PVC) and thermoplastic polyurethane (TPU). PVC film, due to its lower material cost, still holds a significant market share in the car wrap film market, especially in the color-changing market. However, PVC film contains a large amount of plasticizers (such as DOP and DOTP). During use, due to the influence of light and temperature, these plasticizers gradually leach out, causing the pressure-sensitive adhesive to soften and age, thus affecting the car paint and reducing the residual value of the car in the secondary market. Therefore, developing an acrylic pressure-sensitive adhesive for car wrap film with good plasticizer resistance, minimal residue and shadows, and the ability to maintain the original effect of the car paint has become a current research focus.

[0003] Patent CN117004349A discloses a method for preparing an acrylic pressure-sensitive adhesive for PVC color-changing films, controlling the molecular weight to 40,000-60,000, the molecular weight distribution to 5-7, and the glass transition temperature to -30℃--45℃, thereby achieving plasticizer resistance. Patent CN115806787B discloses a method for preparing an acrylic pressure-sensitive adhesive for car wrap films, increasing the crosslinking degree by adding a zirconate coupling agent, thereby resisting plasticizers in the PVC film. Patent CN110669447B discloses an acrylic pressure-sensitive adhesive for PVC decorative films, using a special monomer, ethylidene methacrylate ethoxylate, to improve plasticizer resistance by increasing the crosslinking degree and generating a dense molecular network structure. Patent CN119684938A discloses a plasticizer-resistant acrylic pressure-sensitive adhesive, using polar monomers and polyfunctional acrylate monomers to enhance the adhesive's cohesive strength. The existing technologies described above all achieve plasticizer resistance by increasing the degree of resin crosslinking, but they do not achieve the intrinsic plasticizer resistance of the resin. Therefore, it is necessary to develop a higher-performance and more competitive acrylic pressure-sensitive adhesive for PVC car wrap films to address the problems existing in the current technologies. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an acrylic pressure-sensitive adhesive for PVC car wrap film and its preparation method. By adding acid anhydride substances during the synthesis of the acrylic pressure-sensitive adhesive, the plasticizer resistance of the acrylic pressure-sensitive adhesive can be effectively improved, thereby solving the problems in the prior art. The pressure-sensitive adhesive also has excellent peel strength, ring tack performance and weather resistance, meeting the actual application requirements of car wrap film.

[0005] The objective of this invention can be achieved through the following technical solutions: An acrylic pressure-sensitive adhesive for PVC car wrap film is made from the following raw materials in parts by weight: 100 parts of soft monomer; 10-30 parts hard monomer; 3-10 parts hydroxyacrylic acid monomer; 0.5-1 part initiator; 3-5 parts acid anhydride; 2-4 parts crosslinking agent; 150-200 parts solvent.

[0006] As a preferred embodiment of the present invention, the soft monomer is at least one of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, laurate acrylate, and methyl laurate acrylate.

[0007] As a preferred embodiment of the present invention, the hard monomer is at least one selected from methyl acrylate, methyl methacrylate, acrylic acid, vinyl acetate, glycidyl methacrylate, acrylamide, and isobornyl acrylate.

[0008] As a preferred embodiment of the present invention, the hydroxyacrylic acid monomer is at least one selected from hydroxyethyl methacrylate, hydroxybutyl acrylate, hydroxypropyl acrylate, hydroxymethyl methacrylate, and hydroxyethyl acrylate propoxylate.

[0009] As a preferred embodiment of the present invention, the initiator is selected from at least one of azobisisobutyronitrile and benzoyl peroxide.

[0010] As a preferred embodiment of the present invention, the acid anhydride is at least one of maleic anhydride, succinic anhydride, acetic anhydride, propionic anhydride, and trimellitic anhydride.

[0011] As a preferred embodiment of the present invention, the crosslinking agent is at least one of toluene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate.

[0012] As a preferred embodiment of the present invention, the solvent includes ethyl acetate, toluene, methanol, and N,N-dimethylacetamide.

[0013] In this application, soft monomers, as the main component of the pressure-sensitive adhesive, primarily provide tack and chain segment flexibility, while hard monomers, as the "backbone" of the pressure-sensitive adhesive, primarily provide cohesive strength and peel strength. The hydroxyl groups on the side chains of the hydroxyl acrylic monomers serve as crosslinking sites. During the later stages of preparation or use, these hydroxyl groups can react with the added isocyanate curing agents to form urethane bonds, constructing a robust chemical crosslinking network that significantly enhances the cohesive strength and heat resistance of the adhesive. The mechanism of action of acid anhydride is twofold: (1) First, during the synthesis process, the acid anhydride functional group first undergoes a high-temperature condensation reaction with the isocyanate functional group in the crosslinking agent to generate alternating amide-imide groups; then the unreacted isocyanate functional group undergoes a polymerization reaction with some of the hydroxyl groups on the hydroxy acrylate monomer to generate urethane groups; thus, the acid anhydride is successfully grafted onto the polymer chain (in the form of amide-imide groups), and the acrylate functional group retained on the main chain can also participate in the polymerization reaction with other acrylic monomers to achieve chain extension of the molecular chain, moderately increase the molecular weight, and construct a partially branched or crosslinked structure in advance to enhance the intrinsic strength of the colloidal substance. (2) In addition, a large number of highly polar carboxyl or amide-imide groups are introduced into the polymer chain. When the small molecule plasticizer in the PVC film migrates to the pressure-sensitive adhesive layer, these highly polar groups will generate strong dipole-dipole interactions or even hydrogen bonding with the plasticizer molecules, capturing the migrating plasticizer and effectively preventing it from further penetrating and swelling the acrylic polymer chain. This avoids problems such as excessive softening of the adhesive layer, stickiness, and decreased cohesive strength (i.e., residual adhesive) caused by plasticizer intrusion.

[0014] Furthermore, a method for preparing the acrylic pressure-sensitive adhesive for the PVC car wrap film, employing a semi-continuous titration method, includes the following steps: (1) Remove water from the acid anhydride and crosslinking agent separately for 2-3 hours; (2) Dissolve the dehydrated acid anhydride from step (1) in N,N-dimethylacetamide at 110-130℃, cool to 70-90℃, evacuate, fill with nitrogen for protection, add crosslinking agent, and react for 1-3 hours. (3) Add 70-90% of the initiator, 50-70% of the soft monomer, 50-70% of the hard monomer, and 45-55% of the solvent to the mixture in step (2), and react for 2-3 hours; (4) Add the remaining soft monomer and hard monomer, hydroxyacrylic acid monomer, remaining initiator, and 25-35% solvent, and react for 2-3 hours; (5) Add the remaining solvent and continue stirring for 20-30 minutes to obtain the final product.

[0015] Furthermore, in the method of using the acrylic pressure-sensitive adhesive for the PVC car wrap film, an isocyanate-type curing agent is added during use, and the weight ratio of the pressure-sensitive adhesive to the curing agent is 100:0.5-1.5.

[0016] The beneficial effects of this invention are: (1) This invention introduces strongly polar functional groups into the polymer chain by adding acid anhydride substances during the synthesis process, allowing them to participate in the reaction. These functional groups can capture plasticizers migrating from the PVC base film through strong dipole-dipole interactions, inhibiting the swelling and plasticization of the adhesive layer by the plasticizers, improving the plasticizer resistance of the pressure-sensitive adhesive, and enabling it to maintain excellent stability and elasticity under long-term light and temperature changes, avoiding damage to the original automotive paint due to softening and aging of the adhesive layer, thereby greatly extending the service life of the car paint.

[0017] (2) This invention ensures a uniform polymer composition and appropriate molecular weight distribution through a specific formulation ratio and a semi-continuous titration preparation process. The dense cross-linked network formed by the isocyanate-type curing agent added during use has excellent peel strength and ring-shaped initial tack performance. Furthermore, the hot peel test results after being applied to a steel plate at 100°C for 2 minutes are good, effectively solving the problem of insufficient peel strength of traditional pressure-sensitive adhesives.

[0018] (3) The present invention utilizes a stable three-dimensional crosslinked network constructed by acid anhydride, crosslinking agent, and curing agent, giving the pressure-sensitive adhesive excellent weather resistance. After 1200 hours of UV aging test (340nm, 50℃), the adhesive layer showed no residue, no shadow phenomenon, and no overflow at the edges, significantly improving the long-term performance of the car wrap film. This avoids leaving hard-to-remove marks on the car paint due to adhesive layer deterioration, helps maintain the original appearance and gloss of the car paint, and increases the residual value of the car in secondary transactions.

[0019] (4) The pressure-sensitive adhesive of the present invention has good water resistance and acid and alkali corrosion resistance, and can be used in a wider range of environmental conditions, thus expanding its application range. By optimizing the molecular weight and molecular weight distribution, as well as the selection of soft and hard monomers, the pressure-sensitive adhesive of the present invention maintains good bonding performance while improving its weather resistance in a wide temperature range, thus meeting the application requirements in different environments. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0021] Example 1 An acrylic pressure-sensitive adhesive for PVC car wrap film is made from the following raw materials in parts by weight: 100 parts of soft monomer; 20 parts hard monomer; 6 parts hydroxyacrylic acid monomer; 0.8 parts initiator; 4 parts acid anhydride; 3 parts crosslinking agent; 180 parts solvent.

[0022] The soft monomer is butyl acrylate and 2-ethylhexyl acrylate in a mass ratio of 1:1.

[0023] The hard monomer is methyl methacrylate and acrylic acid in a mass ratio of 8:2.

[0024] The hydroxyacrylic acid monomer is hydroxyethyl methacrylate.

[0025] The initiator is azobisisobutyronitrile.

[0026] The acid anhydride is maleic anhydride.

[0027] The crosslinking agent is toluene diisocyanate.

[0028] The solvent comprises 90 parts by weight of ethyl acetate, 54 parts by weight of toluene, 9 parts by weight of methanol, and 27 parts by weight of N,N-dimethylacetamide.

[0029] A method for preparing the acrylic pressure-sensitive adhesive for the PVC car wrap film, employing a semi-continuous titration method, includes the following steps: (1) Remove water from the acid anhydride and crosslinking agent separately for 2 hours; (2) Dissolve the dehydrated acid anhydride from step (1) in N,N-dimethylacetamide at 120°C, cool it to 80°C, then evacuate it, fill it with nitrogen for protection, add a crosslinking agent, and react for 2 hours. (3) Add 80% of the initiator, 60% of the soft monomer, 60% of the hard monomer, and 50% of the solvent to the mixture in step (2), and react for 2.5 hours; (4) Add the remaining soft monomer and hard monomer, hydroxyacrylic acid monomer, remaining initiator, and 30% solvent, and react for 2.5 hours; (5) Add the remaining solvent and continue stirring for 25 minutes to obtain the final product.

[0030] The method for using the acrylic pressure-sensitive adhesive for PVC car wrap film involves adding HDI trimer curing agent during use, with the weight ratio of pressure-sensitive adhesive to curing agent being 100:1.

[0031] Example 2 An acrylic pressure-sensitive adhesive for PVC car wrap film is made from the following raw materials in parts by weight: 100 parts of soft monomer; 10 parts hard monomer; 3 parts hydroxyacrylic acid monomer; 0.5 parts initiator; 3 parts acid anhydride; 2 parts crosslinking agent; 150 parts solvent.

[0032] The soft monomer is ethyl acrylate.

[0033] The hard monomer is methyl acrylate.

[0034] The hydroxyacrylic acid monomer is hydroxyethyl methacrylate.

[0035] The initiator is azobisisobutyronitrile.

[0036] The acid anhydride is succinic anhydride.

[0037] The crosslinking agent is diphenylmethane diisocyanate.

[0038] The solvent comprises 80 parts by weight of ethyl acetate, 45 parts by weight of toluene, 5 parts by weight of methanol, and 20 parts by weight of N,N-dimethylacetamide.

[0039] A method for preparing the acrylic pressure-sensitive adhesive for the PVC car wrap film, employing a semi-continuous titration method, includes the following steps: (1) Remove water from the acid anhydride and crosslinking agent separately for 2 hours; (2) Dissolve the dehydrated acid anhydride from step (1) in N,N-dimethylacetamide at 110°C, cool to 70°C, evacuate, purge with nitrogen for protection, add crosslinking agent, and react for 1 hour. (3) Add 70% of the initiator, 50% of the soft monomer, 50% of the hard monomer, and 45% of the solvent to the mixture in step (2), and react for 2 hours; (4) Add the remaining soft monomer and hard monomer, hydroxyacrylic acid monomer, remaining initiator, and 25% solvent, and react for 2 hours; (5) Add the remaining solvent and continue stirring for 20 minutes to obtain the final product.

[0040] The method for using the acrylic pressure-sensitive adhesive for PVC car wrap film involves adding HDI biuret curing agent during use, with the weight ratio of pressure-sensitive adhesive to curing agent being 100:0.5.

[0041] Example 3 An acrylic pressure-sensitive adhesive for PVC car wrap film is made from the following raw materials in parts by weight: 100 parts of soft monomer; 30 parts hard monomer; 10 parts hydroxyacrylic acid monomer; 1 initiator; 5 parts acid anhydride; 4 parts crosslinking agent; 200 parts solvent.

[0042] The soft monomer is lauric acid acrylate and lauric acid methacrylate in a mass ratio of 1:1.

[0043] The hard monomer is acrylamide.

[0044] The hydroxyacrylic acid monomer is hydroxymethyl methacrylate.

[0045] The initiator is benzoyl peroxide.

[0046] The acid anhydride is acetic anhydride.

[0047] The crosslinking agent is hexamethylene diisocyanate.

[0048] The solvent comprises 100 parts by weight of ethyl acetate, 60 parts by weight of toluene, 10 parts by weight of methanol and 30 parts by weight of N,N-dimethylacetamide.

[0049] A method for preparing the acrylic pressure-sensitive adhesive for the PVC car wrap film, employing a semi-continuous titration method, includes the following steps: (1) Remove water from the acid anhydride and crosslinking agent separately for 3 hours; (2) Dissolve the dehydrated acid anhydride from step (1) in N,N-dimethylacetamide at 130°C, cool to 90°C, evacuate, purge with nitrogen for protection, add crosslinking agent, and react for 3 hours. (3) Add 90% of the initiator, 70% of the soft monomer, 70% of the hard monomer, and 55% of the solvent to the mixture in step (2), and react for 3 hours; (4) Add the remaining soft monomer and hard monomer, hydroxyacrylic acid monomer, remaining initiator, and 35% solvent, and react for 3 hours; (5) Add the remaining solvent and continue stirring for 30 minutes to obtain the final product.

[0050] The method for using the acrylic pressure-sensitive adhesive for PVC car wrap film involves adding HDI trimer curing agent during use, with the weight ratio of pressure-sensitive adhesive to curing agent being 100:1.5.

[0051] Example 4 An acrylic pressure-sensitive adhesive for PVC car wrap film is made from the following raw materials in parts by weight: 100 parts of soft monomer; 20 parts hard monomer; 6 parts hydroxyacrylic acid monomer; 0.8 parts initiator; 4 parts acid anhydride; 3 parts crosslinking agent; 180 parts solvent.

[0052] The soft monomer is butyl acrylate and 2-ethylhexyl acrylate in a mass ratio of 1:1.

[0053] The hard monomer is methyl methacrylate and acrylic acid in a mass ratio of 8:2.

[0054] The hydroxyacrylic acid monomer is hydroxyethyl methacrylate.

[0055] The initiator is azobisisobutyronitrile.

[0056] The acid anhydride is trimellitic anhydride.

[0057] The crosslinking agent is toluene diisocyanate.

[0058] The solvent comprises 90 parts by weight of ethyl acetate, 54 parts by weight of toluene, 9 parts by weight of methanol, and 27 parts by weight of N,N-dimethylacetamide.

[0059] A method for preparing the acrylic pressure-sensitive adhesive for the PVC car wrap film, employing a semi-continuous titration method, includes the following steps: (1) Remove water from the acid anhydride and crosslinking agent separately for 2 hours; (2) Dissolve the dehydrated acid anhydride from step (1) in N,N-dimethylacetamide at 120°C, cool it to 80°C, then evacuate it, fill it with nitrogen for protection, add a crosslinking agent, and react for 2 hours. (3) Add 80% of the initiator, 60% of the soft monomer, 60% of the hard monomer, and 50% of the solvent to the mixture in step (2), and react for 2.5 hours; (4) Add the remaining soft monomer and hard monomer, hydroxyacrylic acid monomer, remaining initiator, and 30% solvent, and react for 2.5 hours; (5) Add the remaining solvent and continue stirring for 25 minutes to obtain the final product.

[0060] The method for using the acrylic pressure-sensitive adhesive for PVC car wrap film involves adding HDI trimer curing agent during use, with the weight ratio of pressure-sensitive adhesive to curing agent being 100:1.

[0061] Comparative Example 1 Based on Example 1, no acid anhydride was added, and everything else remained the same as in Example 1.

[0062] Comparative Example 2 Based on Example 1, the amount of acid anhydride added was changed to 1 part by weight, while the rest remained the same as in Example 1.

[0063] Comparative Example 3 Based on Example 1, without performing the pre-reaction treatment of the acid anhydride in step (2), the acid anhydride was added together with the remaining monomers, and the rest remained the same as in Example 1.

[0064] Comparative Example 4 Referring to Example 1 in CN115806787B, a pressure-sensitive adhesive that is resistant to plasticizers by adding a zirconate coupling agent to improve the degree of crosslinking was prepared.

[0065] Performance testing: The pressure-sensitive adhesive obtained in the examples and comparative examples was evenly coated onto a 100μm thick PVC base film using a scraper. It was then dried in a 120°C oven for 2 minutes to allow the solvent to fully evaporate. The dried tape was then cured at 60°C for 48 hours to finally control the thickness of the dry adhesive layer to 30μm. When applying the tape, use a standard film-applying roller (2kg weight, three round trips) to apply the prepared tape to the designated test plate, ensuring no air bubbles. After application, let it stand for 20-30 minutes before testing.

[0066] 180° Peel Strength: According to GB / T 2792-2014, the tape is applied to a clean stainless steel plate and a 180° peel test is performed on a universal tensile testing machine at a speed of 300 mm / min. Ring initial tack: A ring is formed according to GB / T 31125-2014 standard, pressed against the stainless steel plate at a speed of 300 mm / min and then pulled apart. The maximum force value is recorded to test the ring initial tack. Hot peel strength: After the tape is applied to the steel plate, it is placed in a high temperature peel test chamber, baked at 100℃ for 2 minutes, and then its 180° peel strength is directly tested under 100℃ conditions. Weathering resistance test: The test was conducted in a UV aging chamber according to ISO 4892, under the following conditions: UVA-340 lamp, irradiance 0.76W / m². 2 After 1200 hours of continuous light exposure at a blackboard temperature of 50℃, the appearance was evaluated and the peel strength was tested. Hydrolysis resistance: Immerse the test panel with the tape attached in 40℃ warm water for 7 days. Remove, dry, test the peel strength, and observe whether it peels off or turns white. Chemical corrosion resistance: Use a cotton swab dipped in 5% NaOH solution and 5% H2SO4 solution to repeatedly wipe the surface of the steel plate with tape. After standing for 24 hours, observe the changes on the edge of the tape and the surface of the plate.

[0067] The test results show that the examples exhibited excellent and balanced performance in all tests, with high peel strength, excellent heat resistance, and weather resistance, verifying the success of the formulation and process of this preparation method. Comparative Example 1, without the addition of acid anhydride, although showing good initial adhesion, exhibited extremely poor aging resistance and plasticizer resistance, resulting in severe residue and shadows after UV aging, completely failing to meet the requirements for automotive coating film use. This highlights that acid anhydride is an indispensable key component for achieving "plasticizer resistance." Comparative Example 2, with insufficient acid anhydride, resulted in performance between the examples and Comparative Example 1, with significant differences in all indicators. The performance of Comparative Example 3 declined, especially after aging, with residual adhesive appearing. Comparative Example 3, without the pre-reaction treatment of acid anhydride, showed a significant decrease in hot peel strength and aging resistance, with edge overflow and shadows appearing. This demonstrates that the pre-reaction process of acid anhydride is crucial for building a stable and dense cross-linked network, and simple physical mixing cannot achieve the effect of chemical modification. Comparative Example 4 (existing technology) had relatively low initial peel strength and initial tack, and still showed slight residual adhesive after UV aging. Existing technologies that simply increase the degree of cross-linking (such as adding zirconate ester) are not as good as the double cross-linking of acid anhydride in terms of overall performance balance.

[0068] The data results analysis and explanation described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An acrylic pressure-sensitive adhesive for PVC car wrap film, characterized in that, Made from the following parts by weight of raw materials: 100 parts of soft monomer; 10-30 parts hard monomer; 3-10 parts hydroxyacrylic acid monomer; 0.5-1 part initiator; 3-5 parts acid anhydride; 2-4 parts crosslinking agent; 150-200 parts solvent.

2. The acrylic pressure-sensitive adhesive for PVC car wrap film according to claim 1, characterized in that, The soft monomer is at least one of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, laurate acrylate, and methyl laurate acrylate.

3. The acrylic pressure-sensitive adhesive for PVC car wrap film according to claim 1, characterized in that, The hard monomer is at least one of methyl acrylate, methyl methacrylate, acrylic acid, vinyl acetate, glycidyl methacrylate, acrylamide, and isobornyl acrylate.

4. The acrylic pressure-sensitive adhesive for PVC car wrap film according to claim 1, characterized in that, The hydroxyacrylic acid monomer is at least one of hydroxyethyl methacrylate, hydroxybutyl acrylate, hydroxypropyl acrylate, hydroxymethyl methacrylate, and hydroxyethyl acrylate propoxylate.

5. The acrylic pressure-sensitive adhesive for PVC car wrap film according to claim 1, characterized in that, The initiator is selected from at least one of azobisisobutyronitrile and benzoyl peroxide.

6. The acrylic pressure-sensitive adhesive for PVC car wrap film according to claim 1, characterized in that, The anhydride is at least one of maleic anhydride, succinic anhydride, acetic anhydride, propionic anhydride, and trimellitic anhydride.

7. The acrylic pressure-sensitive adhesive for PVC car wrap film according to claim 1, characterized in that, The crosslinking agent is at least one of toluene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate.

8. The acrylic pressure-sensitive adhesive for PVC car wrap film according to claim 1, characterized in that, The solvents include ethyl acetate, toluene, methanol, and N,N-dimethylacetamide.

9. A method for preparing an acrylic pressure-sensitive adhesive for PVC car wrap film as described in any one of claims 1-8, characterized in that, The semi-continuous titration method includes the following steps: (1) Remove water from the acid anhydride and crosslinking agent separately for 2-3 hours; (2) Dissolve the dehydrated acid anhydride from step (1) in N,N-dimethylacetamide at 110-130℃, cool to 70-90℃, evacuate, fill with nitrogen for protection, add crosslinking agent, and react for 1-3 hours. (3) Add 70-90% of the initiator, 50-70% of the soft monomer, 50-70% of the hard monomer, and 45-55% of the solvent to the mixture in step (2), and react for 2-3 hours; (4) Add the remaining soft monomer and hard monomer, hydroxyacrylic acid monomer, remaining initiator, and 25-35% solvent, and react for 2-3 hours; (5) Add the remaining solvent and continue stirring for 20-30 minutes to obtain the final product.

10. A method of using an acrylic pressure-sensitive adhesive for PVC car wrap film as described in any one of claims 1-8, characterized in that, When using, add an isocyanate-type curing agent, and the weight ratio of pressure-sensitive adhesive to curing agent is 100:0.5-1.5.

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