A plasticizer-resistant acrylic pressure-sensitive adhesive

Abstract

This invention discloses a plasticizer-resistant acrylate pressure-sensitive adhesive in the field of pressure-sensitive adhesive technology. Through the synergistic effect of soft monomers, hard monomers, highly polar monomers, and polyfunctional acrylate monomers, the prepared acrylate pressure-sensitive adhesive, when used in flexible PVC films, exhibits the following advantages: Firstly, the high polarity of the acrylate pressure-sensitive adhesive layer deteriorates the compatibility with small-molecule plasticizers in PVC, making it less likely for plasticizers to migrate into the adhesive layer, while simultaneously improving the peel strength of the acrylate pressure-sensitive adhesive. Secondly, it further enhances the cohesion of the acrylate pressure-sensitive adhesive, reducing the problem of residual adhesive and peel strength attenuation caused by the deterioration of cohesion due to plasticizer migration.

Description

Technical Field

[0001] This invention relates to the field of pressure-sensitive adhesive technology, specifically to a plasticizer-resistant acrylic pressure-sensitive adhesive. Background Technology

[0002] Flexible polyvinyl chloride (PVC) film has good elongation, tear strength, cold resistance, and corrosion resistance. It also has excellent printability and low price. Therefore, flexible PVC pressure-sensitive tapes (vehicle stickers, advertising stickers, etc.) made from it are widely used in the automotive, advertising, home appliance and home decoration industries.

[0003] However, flexible PVC films contain a large number of small molecule plasticizers, such as dioctyl phthalate (DOP) and dibutyl phthalate (DBP). Although the addition of plasticizers can improve the plasticity and low-temperature resistance of PVC, over time, the small molecule plasticizers will slowly migrate to the interface between the substrate and the film or migrate into the film. This will lead to a serious decline in the adhesion of the pressure-sensitive adhesive layer or damage to the cohesion of the adhesive layer, making it easy to leave adhesive residue when peeling off, thus limiting the application of flexible PVC pressure-sensitive adhesive tapes. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] Therefore, the purpose of this invention is to provide a plasticizer-resistant acrylic pressure-sensitive adhesive that has good plasticizer resistance and does not leave residue after peeling after aging, and has minimal degradation in adhesive performance.

[0006] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0007] A plasticizer-resistant acrylic pressure-sensitive adhesive comprises the following components by weight:

[0008] Soft monomer: 30-40 parts, hard monomer: 2-6 parts, polar monomer: 4-6 parts, polyfunctional acrylate monomer: 0.01-0.1 parts, initiator: 0.1-0.3 parts, solvent: 55-65 parts, curing agent: 0.3-0.8 parts;

[0009] The specific preparation steps for the plasticizer-resistant acrylate pressure-sensitive adhesive are as follows:

[0010] S1. Weigh out the soft monomer, hard monomer, polar monomer, and polyfunctional acrylate monomer and mix them to obtain a mixed monomer.

[0011] S2. Mix a portion of the mixed monomers with a portion of the solvent, heat to 65-80℃ under an inert atmosphere, add a portion of the initiator, and keep the reaction at the solvent reflux temperature to obtain reaction solution one;

[0012] S3. Add the remaining mixed monomers, a portion of the solvent, and a portion of the initiator dropwise into reaction solution one, and keep the reaction at the solvent reflux temperature to obtain reaction solution two;

[0013] S4. Add the remaining initiator to the reaction solution two, and keep the reaction at the solvent reflux temperature to obtain reaction solution three;

[0014] S5. Cool the reaction solution to below 50°C, add the remaining solvent and curing agent, stir, and obtain plasticizer-resistant acrylate pressure-sensitive adhesive.

[0015] As a preferred embodiment of the plasticizer-resistant acrylate pressure-sensitive adhesive of the present invention, the soft monomer is selected from at least one of n-butyl acrylate, isobutyl acrylate, and sec-butyl acrylate.

[0016] As a preferred embodiment of the plasticizer-resistant acrylate pressure-sensitive adhesive of the present invention, the hard monomer is selected from at least one of methyl acrylate, tert-butyl acrylate, and vinyl acetate.

[0017] In a preferred embodiment of the plasticizer-resistant acrylate pressure-sensitive adhesive of the present invention, the polar monomer is at least one of acrylonitrile and acrylamide.

[0018] As a preferred embodiment of the plasticizer-resistant acrylate pressure-sensitive adhesive of the present invention, the polyfunctional acrylate monomer is at least one of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, and bis(trimethylolpropane)tetraacrylate.

[0019] As a preferred embodiment of the plasticizer-resistant acrylate pressure-sensitive adhesive of the present invention, the initiator is selected from at least one of azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, and benzoyl peroxide.

[0020] In a preferred embodiment of the plasticizer-resistant acrylate pressure-sensitive adhesive of the present invention, the solvent is selected from at least one of ethyl acetate, heptane, ethanol, isopropanol, and toluene.

[0021] In a preferred embodiment of the plasticizer-resistant acrylate pressure-sensitive adhesive of the present invention, the curing agent is aluminum acetylacetonate-acetylacetonate.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] Through the synergistic effect of soft monomers, hard monomers, polar monomers, and polyfunctional acrylate monomers, the prepared acrylate pressure-sensitive adhesive, when used in flexible PVC films, exhibits the following advantages: Firstly, the high polarity of the acrylate pressure-sensitive adhesive layer reduces the compatibility with small-molecule plasticizers in PVC, making it less likely for plasticizers to migrate into the adhesive layer, thus improving the peel strength of the acrylate pressure-sensitive adhesive. Secondly, it further enhances the cohesion of the acrylate pressure-sensitive adhesive, reducing the problem of residual adhesive and peel strength decay caused by poor cohesion due to plasticizer migration.

[0024] Based on the characteristic that small molecule plasticizers (DOP, DBP, etc.) in flexible PVC films have relatively low polarity, and according to the principle of "like dissolves like," polar monomers are introduced into the system to increase the overall polarity of the acrylic pressure-sensitive adhesive. This also reduces the compatibility between the acrylic pressure-sensitive adhesive and the plasticizer, making it less likely for the plasticizer to migrate into the adhesive layer. Simultaneously, a higher content of polar groups (-CN, -CONH2, etc.) can improve the adhesion of the acrylic pressure-sensitive adhesive and reduce the peel strength reduction problem caused by plasticizer migration. Furthermore, this application also introduces polyfunctional acrylic monomers (functionality ≥3) into the system to further improve the cohesion of the acrylic system, further mitigating the phenomenon of residual adhesive caused by poor cohesion due to plasticizer migration.

[0025] This invention employs a special preparation method, heating to 65-80℃ under an inert atmosphere to ensure that the influence of oxygen inhibition on the polymerization reaction is reduced under a nitrogen atmosphere, making the polymerization reaction more stable. The dropwise addition method can better control the exothermic polymerization reaction and the molecular weight. Furthermore, the initiator is added in multiple stages because it is gradually consumed during polymerization. Therefore, the distributed addition improves the monomer conversion rate and controls the molecular weight to ensure a fully stable polymerization reaction. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0027] Figure 1 This is a schematic diagram showing the test results of the plasticizer-resistant acrylate pressure-sensitive adhesives prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0030] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0031] Existing acrylic pressure-sensitive adhesives typically synthesize adhesives with poor compatibility with plasticizers by using as few long-chain acrylate monomers as possible, primarily employing short-chain butyl acrylate and methyl acrylate as the soft monomers. This makes it difficult for plasticizers to migrate into the adhesive layer, thus preventing a decrease in the cohesive properties of the adhesive film and minimizing residue buildup during peeling. However, the acrylic pressure-sensitive adhesive prepared by this method has a relatively low peel strength. Furthermore, the method design only considers the impact of plasticizers on the cohesive properties of the adhesive layer, neglecting the degradation of adhesive adhesion due to plasticizer migration, i.e., peel strength reduction. This reduction in peel strength can lead to edge curling, slippage, and detachment of flexible PVC pressure-sensitive tapes during long-term use, affecting product usability.

[0032] Based on this, the plasticizer-resistant acrylate pressure-sensitive adhesive provided in this application, according to the characteristics of soft PVC, simultaneously introduces polar monomers and polyfunctional acrylate monomers into the system. This is to improve the overall polarity of the acrylate pressure-sensitive adhesive, making it less likely for plasticizers to migrate into the adhesive layer and improving the adhesion of the acrylate pressure-sensitive adhesive, while further improving the cohesion of the acrylate system and reducing the phenomenon of easy residue formation. The plasticizer-resistant acrylate pressure-sensitive adhesive includes the following weight components: soft monomer: 30-40 parts, hard monomer: 2-6 parts, polar monomer: 4-6 parts, polyfunctional acrylate monomer: 0.01-0.1 parts, initiator: 0.1-0.3 parts, solvent: 55-65 parts, curing agent: 0.3-0.8 parts.

[0033] To ensure the cohesive strength of the acrylate pressure-sensitive adhesive, this application preferably uses at least one of the following polyfunctional acrylate monomers: trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, and bis(trimethylolpropane)tetraacrylate. Using these acrylate monomers with a functionality ≥3 can achieve a higher degree of crosslinking than conventional internal crosslinking monomers (such as N-hydroxymethylacrylamide or hydroxyethylacrylamide), resulting in higher cohesive strength of the acrylate pressure-sensitive adhesive. Furthermore, the polyfunctional acrylate monomers form a network crosslinking system during the polymerization process of the acrylate pressure-sensitive adhesive, exhibiting higher stability than conventional internal crosslinking monomers that require subsequent high-temperature crosslinking and curing.

[0034] To avoid or reduce the migration of small molecule plasticizers to the adhesive layer while maintaining the adhesion of the pressure-sensitive adhesive, this application preferably selects at least one polar monomer from acrylonitrile and acrylamide. The polarity of the nitrile group in acrylonitrile and the amide group in acrylamide is higher than that of the carboxyl and hydroxyl groups. Therefore, the introduction of acrylonitrile or acrylamide can make the acrylate pressure-sensitive adhesive more polar, thereby improving the plasticizer resistance and obtaining higher adhesion.

[0035] To balance the plasticizer resistance and adhesion of the acrylate pressure-sensitive adhesive, this application preferably selects the soft monomer from at least one of n-butyl acrylate, isobutyl acrylate, and sec-butyl acrylate; preferably selects the hard monomer from at least one of methyl acrylate, tert-butyl acrylate, and vinyl acetate; preferably selects the initiator from at least one of azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, and benzoyl peroxide; preferably selects the solvent from at least one of ethyl acetate, heptane, ethanol, isopropanol, and toluene; and preferably selects the curing agent as aluminum acetylacetonate-acetylacetone.

[0036] To verify the technical effect of the plasticizer-resistant acrylate pressure-sensitive adhesive of the present invention, the following Examples 1-4 and Comparative Examples 1-4 are provided. Example 1

[0037] S1. Add 32 parts by weight of soft monomer butyl acrylate, 4 parts by weight of hard monomer methyl acrylate, 5 parts by weight of polar monomer acrylonitrile, and 0.01 parts by weight of polyfunctional acrylate monomer trimethylolpropane triacrylate to a 250mL beaker and stir to mix evenly to obtain mixed monomers.

[0038] S2. In a 1L four-necked flask equipped with a stirrer, thermometer, and reflux condenser, add 25 parts by weight of the mixed monomers from step S1 and 30 parts by weight of ethyl acetate. After purging with nitrogen for 30 minutes, heat to 65°C in a constant temperature water bath. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 1 part by weight of ethyl acetate and add to the reaction flask. After the reaction is initiated, the solvent is stably refluxed. The reaction is kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution one.

[0039] S3. Mix the remaining mixed monomers from step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyronitrile evenly, and add them dropwise evenly to reaction solution one in the reaction flask using a constant pressure dropping funnel. The dropping time is 1 hour. After the dropping is completed, keep the reaction at the solvent reflux temperature for 1 hour to obtain reaction solution two.

[0040] S4. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 4.6 parts by weight of ethyl acetate completely, then add the solution to reaction solution two in the reaction flask. Keep the reaction at the solvent reflux temperature for 3 hours to obtain reaction solution three.

[0041] S5. After the reaction is complete, cool down to below 50°C and add 3.8 parts by weight of isopropanol, 7.7 parts by weight of ethanol, 0.2 parts by weight of aluminum acetylacetonate, and 0.4 parts by weight of acetylacetonate. Stir thoroughly to obtain plasticizer-resistant acrylate pressure-sensitive adhesive. Example 2

[0042] S1. 26.7 parts by weight of soft monomer butyl acrylate, 6 parts by weight of isobutyl acrylate, 3 parts by weight of hard monomer vinyl acetate, 3 parts by weight of polar monomer acrylonitrile, 2 parts by weight of acrylamide, and 0.01 parts by weight of polyfunctional acrylate monomer trimethylolpropane trimethacrylate are added to a 250mL beaker and stirred to mix evenly to obtain mixed monomers.

[0043] S2. In a 1L four-necked flask equipped with a stirrer, thermometer, and reflux condenser, add 27 parts by weight of the mixed monomer from step S1 and 27 parts by weight of heptane. After purging with nitrogen for 30 minutes, heat to 75°C in a constant temperature water bath. Dissolve 0.03 parts by weight of azobisisobutyronitrile in 1 part by weight of ethyl acetate and add to the reaction flask. After the reaction is initiated, the solvent is stably refluxed. The reaction is kept at the solvent reflux temperature for 1 hour to obtain reaction solution one.

[0044] S3. Mix the remaining mixed monomers from step S1, 13.88 parts by weight of ethyl acetate, and 0.1 parts by weight of azobisisobutyronitrile evenly, and add them dropwise evenly to reaction solution one in the reaction flask using a constant pressure dropping funnel. The dropping time is 1.5 hours. After the dropping is completed, keep the reaction at the solvent reflux temperature for 1 hour to obtain reaction solution two.

[0045] S4. Dissolve 0.03 parts by weight of azobisisobutyronitrile in 4.6 parts by weight of ethyl acetate completely, then add it to reaction solution two in the reaction flask. Keep the reaction at the solvent reflux temperature for 4 hours to obtain reaction solution three.

[0046] S5. After the reaction is complete, cool down to below 50°C and add 5 parts by weight of isopropanol, 6.5 parts by weight of toluene, 0.25 parts by weight of aluminum acetylacetonate, and 0.5 parts by weight of acetylacetonate. Stir thoroughly to obtain plasticizer-resistant acrylic pressure-sensitive adhesive. Example 3

[0047] S1. Add 30 parts by weight of soft monomer butyl acrylate, 3.6 parts by weight of sec-butyl acrylate, 2.4 parts by weight of hard monomer tert-butyl acrylate, 2 parts by weight of polar monomer acrylonitrile, 3 parts by weight of acrylamide, and 0.02 parts by weight of polyfunctional acrylate monomer pentaerythritol triacrylate to a 250mL beaker and stir to mix evenly to obtain mixed monomers.

[0048] S2. In a 1L four-necked flask equipped with a stirrer, thermometer, and reflux condenser, add 25 parts by weight of the mixed monomer from step S1, 20.5 parts by weight of ethyl acetate, and 10 parts by weight of heptane. After purging with nitrogen for 30 minutes, heat to 70°C in a constant temperature water bath. Dissolve 0.03 parts by weight of azobisisovalerate in 1 part by weight of ethyl acetate and add it to the reaction flask. After the reaction is initiated, the solvent is stably refluxed. The reaction is kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution one.

[0049] S3. Mix the remaining mixed monomers from step S1, 10.8 parts by weight of ethyl acetate, and 0.12 parts by weight of azobisisovalerate evenly, and add the mixture dropwise evenly to reaction solution one in the reaction flask using a constant pressure dropping funnel. The dropping time is 1 hour. After the dropping is completed, keep the reaction at the solvent reflux temperature for 1.5 hours to obtain reaction solution two.

[0050] S4. Dissolve 0.02 parts by weight of azobisisovalerate in 4.6 parts by weight of ethyl acetate completely, then add it to reaction solution two in the reaction flask. Keep the reaction at the solvent reflux temperature for 2.5 h to obtain reaction solution three.

[0051] S5. After the reaction is complete, the temperature is lowered to below 50°C. Then, 6.9 parts by weight of ethanol, 4.5 parts by weight of toluene, 0.28 parts by weight of aluminum acetylacetonate, and 0.43 parts by weight of acetylacetonate are added and stirred thoroughly to obtain plasticizer-resistant acrylic pressure-sensitive adhesive. Example 4

[0052] S1. Add 32 parts by weight of soft monomer butyl acrylate, 4 parts by weight of hard monomer methyl acrylate, 5 parts by weight of polar monomer acrylamide, and 0.01 parts by weight of polyfunctional acrylate monomer bis(trimethylolpropanetetraacrylate) to a 250mL beaker and stir to mix evenly to obtain mixed monomers.

[0053] S2. In a 1L four-necked flask equipped with a stirrer, thermometer, and reflux condenser, add 25 parts by weight of the mixed monomers from step S1 and 30 parts by weight of ethyl acetate. After purging with nitrogen for 30 minutes, heat to 65°C in a constant temperature water bath. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 1 part by weight of ethyl acetate and add to the reaction flask. After the reaction is initiated, the solvent is stably refluxed. The reaction is kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution one.

[0054] S3. Mix the remaining mixed monomers from step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyronitrile evenly, and add them dropwise evenly to reaction solution one in the reaction flask using a constant pressure dropping funnel. The dropping time is 1 hour. After the dropping is completed, keep the reaction at the solvent reflux temperature for 1 hour to obtain reaction solution two.

[0055] S4. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 4.6 parts by weight of ethyl acetate completely, then add the solution to reaction solution two in the reaction flask. Keep the reaction at the solvent reflux temperature for 3 hours to obtain reaction solution three.

[0056] S5. After the reaction is complete, cool down to below 50°C and add 3.8 parts by weight of isopropanol, 7.7 parts by weight of ethanol, 0.2 parts by weight of aluminum acetylacetonate, and 0.4 parts by weight of acetylacetonate. Stir thoroughly to obtain plasticizer-resistant acrylate pressure-sensitive adhesive.

[0057] Comparative Example 1

[0058] S1. Add 32 parts by weight of soft monomer butyl acrylate, 4 parts by weight of hard monomer methyl acrylate, and 5 parts by weight of polar monomer acrylonitrile to a 250mL beaker and stir to mix evenly to obtain mixed monomers.

[0059] S2. In a 1L four-necked flask equipped with a stirrer, thermometer, and reflux condenser, add 25 parts by weight of the mixed monomers from step S1 and 30 parts by weight of ethyl acetate. After purging with nitrogen for 30 minutes, heat to 65°C in a constant temperature water bath. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 1 part by weight of ethyl acetate and add to the reaction flask. After the reaction is initiated, the solvent is stably refluxed. The reaction is kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution one.

[0060] S3. Mix the remaining mixed monomers from step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyronitrile evenly, and add them dropwise evenly to reaction solution one in the reaction flask using a constant pressure dropping funnel. The dropping time is 1 hour. After the dropping is completed, keep the reaction at the solvent reflux temperature for 1 hour to obtain reaction solution two.

[0061] S4. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 4.6 parts by weight of ethyl acetate completely, then add the solution to reaction solution two in the reaction flask. Keep the reaction at the solvent reflux temperature for 3 hours to obtain reaction solution three.

[0062] S5. After the reaction is complete, cool down to below 50°C and add 3.8 parts by weight of isopropanol, 7.7 parts by weight of ethanol, 0.2 parts by weight of aluminum acetylacetonate, and 0.4 parts by weight of acetylacetonate. Stir thoroughly to obtain plasticizer-resistant acrylate pressure-sensitive adhesive.

[0063] The difference between this comparative example and Example 1 is that no polyfunctional acrylate monomer was added to the system.

[0064] Comparative Example 2

[0065] S1. Add 32 parts by weight of soft monomer butyl acrylate, 4 parts by weight of hard monomer methyl acrylate, 5 parts by weight of polar monomer acrylonitrile, and 0.01 parts by weight of N-hydroxymethylacrylamide into a 250mL beaker and stir to mix evenly to obtain a mixed monomer.

[0066] S2. In a 1L four-necked flask equipped with a stirrer, thermometer, and reflux condenser, add 25 parts by weight of the mixed monomers from step S1 and 30 parts by weight of ethyl acetate. After purging with nitrogen for 30 minutes, heat to 65°C in a constant temperature water bath. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 1 part by weight of ethyl acetate and add to the reaction flask. After the reaction is initiated, the solvent is stably refluxed. The reaction is kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution one.

[0067] S3. Mix the remaining mixed monomers from step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyronitrile evenly, and add them dropwise evenly to reaction solution one in the reaction flask using a constant pressure dropping funnel. The dropping time is 1 hour. After the dropping is completed, keep the reaction at the solvent reflux temperature for 1 hour to obtain reaction solution two.

[0068] S4. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 4.6 parts by weight of ethyl acetate completely, then add the solution to reaction solution two in the reaction flask. Keep the reaction at the solvent reflux temperature for 3 hours to obtain reaction solution three.

[0069] S5. After the reaction is complete, cool down to below 50°C and add 3.8 parts by weight of isopropanol, 7.7 parts by weight of ethanol, 0.2 parts by weight of aluminum acetylacetonate, and 0.4 parts by weight of acetylacetonate. Stir thoroughly to obtain plasticizer-resistant acrylate pressure-sensitive adhesive.

[0070] The difference between this comparative example and Example 1 is that N-hydroxymethylacrylamide is used to replace trimethylolpropane triacrylate in the system.

[0071] Comparative Example 3

[0072] S1. Add 32 parts by weight of soft monomer butyl acrylate, 4 parts by weight of hard monomer methyl acrylate, and 0.01 parts by weight of polyfunctional acrylate monomer trimethylolpropane triacrylate to a 250mL beaker and stir to mix evenly to obtain mixed monomers.

[0073] S2. In a 1L four-necked flask equipped with a stirrer, thermometer, and reflux condenser, add 25 parts by weight of the mixed monomers from step S1 and 30 parts by weight of ethyl acetate. After purging with nitrogen for 30 minutes, heat to 65°C in a constant temperature water bath. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 1 part by weight of ethyl acetate and add to the reaction flask. After the reaction is initiated, the solvent is stably refluxed. The reaction is kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution one.

[0074] S3. Mix the remaining mixed monomers from step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyronitrile evenly, and add them dropwise evenly to reaction solution one in the reaction flask using a constant pressure dropping funnel. The dropping time is 1 hour. After the dropping is completed, keep the reaction at the solvent reflux temperature for 1 hour to obtain reaction solution two.

[0075] S4. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 4.6 parts by weight of ethyl acetate completely, then add the solution to reaction solution two in the reaction flask. Keep the reaction at the solvent reflux temperature for 3 hours to obtain reaction solution three.

[0076] S5. After the reaction is complete, cool down to below 50°C and add 3.8 parts by weight of isopropanol, 7.7 parts by weight of ethanol, 0.2 parts by weight of aluminum acetylacetonate, and 0.4 parts by weight of acetylacetonate. Stir thoroughly to obtain plasticizer-resistant acrylate pressure-sensitive adhesive.

[0077] The difference between this comparative example and Example 1 is that no polar monomer was added to the system.

[0078] Comparative Example 4

[0079] S1. Add 32 parts by weight of soft monomer butyl acrylate, 4 parts by weight of hard monomer methyl acrylate, 5 parts by weight of acrylic acid, and 0.01 parts by weight of polyfunctional acrylate monomer trimethylolpropane triacrylate to a 250mL beaker and stir to mix evenly to obtain mixed monomers.

[0080] S2. In a 1L four-necked flask equipped with a stirrer, thermometer, and reflux condenser, add 25 parts by weight of the mixed monomers from step S1 and 30 parts by weight of ethyl acetate. After purging with nitrogen for 30 minutes, heat to 65°C in a constant temperature water bath. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 1 part by weight of ethyl acetate and add to the reaction flask. After the reaction is initiated, the solvent is stably refluxed. The reaction is kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution one.

[0081] S3. Mix the remaining mixed monomers from step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyronitrile evenly, and add them dropwise evenly to reaction solution one in the reaction flask using a constant pressure dropping funnel. The dropping time is 1 hour. After the dropping is completed, keep the reaction at the solvent reflux temperature for 1 hour to obtain reaction solution two.

[0082] S4. Dissolve 0.02 parts by weight of azobisisobutyronitrile in 4.6 parts by weight of ethyl acetate completely, then add the solution to reaction solution two in the reaction flask. Keep the reaction at the solvent reflux temperature for 3 hours to obtain reaction solution three.

[0083] S5. After the reaction is complete, cool down to below 50°C and add 3.8 parts by weight of isopropanol, 7.7 parts by weight of ethanol, 0.2 parts by weight of aluminum acetylacetonate, and 0.4 parts by weight of acetylacetonate. Stir thoroughly to obtain plasticizer-resistant acrylate pressure-sensitive adhesive.

[0084] The difference between this comparative example and Example 1 is that acrylic acid is used instead of the polar monomer acrylonitrile.

[0085] The plasticizer-resistant acrylic pressure-sensitive adhesives prepared in the above embodiments and comparative examples were uniformly coated onto release paper using a scraper. The paper was baked at 120°C for 2 minutes and then transferred to a 90μm soft PVC substrate to obtain a soft PVC pressure-sensitive adhesive tape sample with a dry adhesive thickness of 25μm. Finally, the sample was cured at 40°C for 3 days before performance testing.

[0086] The plasticizer-resistant acrylic pressure-sensitive adhesives prepared in the above embodiments and comparative examples were uniformly coated onto release paper using a scraper. The paper was baked at 120°C for 2 minutes and then transferred to a 90μm soft PVC substrate to obtain a soft PVC pressure-sensitive adhesive tape sample with a dry adhesive thickness of 25μm. Finally, the sample was cured at 40°C for 3 days before performance testing.

[0087] Test results are as follows Figure 1 As shown in the test results, the plasticizer-resistant acrylate pressure-sensitive adhesives prepared in the various embodiments of the present invention exhibit excellent plasticizer resistance. Introducing a higher content of polar groups using highly polar monomers to enhance the polarity of the acrylate significantly improves resistance to plasticizer migration. The prepared PVC tape shows a peel strength decrease of no more than 10% after high-temperature and high-humidity aging. Furthermore, the use of polyfunctional acrylate monomers further enhances the cohesion of the acrylate, resulting in no residue after peeling after aging, and the effect is superior to that of conventional internal crosslinking monomers.

[0088] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A plasticizer-resistant acrylic pressure-sensitive adhesive, characterized in that, Includes the following components by weight: Soft monomer: 30-40 parts, hard monomer: 2-6 parts, polar monomer: 4-6 parts, polyfunctional acrylate monomer: 0.01-0.1 parts, initiator: 0.1-0.3 parts, solvent: 55-65 parts, curing agent: 0.3-0.8 parts; The polar monomer is at least one of acrylonitrile and acrylamide, the polyfunctional acrylate monomer is at least one of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, and bis(trimethylolpropane tetraacrylate), and the curing agent is aluminum acetylacetonate-acetylacetonate. The specific preparation steps for the plasticizer-resistant acrylate pressure-sensitive adhesive are as follows: S1. Weigh out the soft monomer, hard monomer, polar monomer, and polyfunctional acrylate monomer and mix them to obtain a mixed monomer. S2. Mix a portion of the mixed monomers with a portion of the solvent, heat to 65-80℃ under an inert atmosphere, add a portion of the initiator, and keep the reaction at the solvent reflux temperature to obtain reaction solution one; S3. Add the remaining mixed monomers, a portion of the solvent, and a portion of the initiator dropwise into reaction solution one, and keep the reaction at the solvent reflux temperature to obtain reaction solution two; S4. Add the remaining initiator to the reaction solution two, and keep the reaction at the solvent reflux temperature to obtain reaction solution three; S5. Cool the reaction solution to below 50°C, add the remaining solvent and curing agent, stir, and obtain plasticizer-resistant acrylate pressure-sensitive adhesive.

2. The plasticizer-resistant acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The soft monomer is selected from at least one of n-butyl acrylate, isobutyl acrylate, and sec-butyl acrylate.

3. The plasticizer-resistant acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The hard monomer is selected from at least one of methyl acrylate, tert-butyl acrylate, and vinyl acetate.

4. The plasticizer-resistant acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The initiator is selected from at least one of azobisisobutyronitrile, azobisisovalerate, azobisisoheptanenitrile, and benzoyl peroxide.

5. The plasticizer-resistant acrylic pressure-sensitive adhesive according to claim 1, characterized in that, The solvent is selected from at least one of ethyl acetate, heptane, ethanol, isopropanol, and toluene.

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