Plasticizer-resistant acrylate pressure-sensitive adhesive

Abstract

The invention discloses a plasticizer-resistant acrylate pressure-sensitive adhesive in the technical field of pressure-sensitive adhesives, and through the synergistic effect of a soft monomer, a hard monomer, a strong polar monomer and a polyfunctional acrylate monomer, when the prepared acrylate pressure-sensitive adhesive is used for a soft PVC film, the plasticizer-resistant acrylate pressure-sensitive adhesive has the advantages that the plasticizer-resistant property is good; on one hand, the compatibility between the high-polarity acrylate pressure-sensitive adhesive layer and a small-molecular plasticizer in PVC becomes poor, the plasticizer is not easy to migrate into the adhesive layer, and meanwhile, the stripping force of the acrylate pressure-sensitive adhesive can be improved; on the other hand, the cohesion of the acrylate pressure-sensitive adhesive is further improved, and the problems of adhesive residue phenomenon and stripping force attenuation during stripping caused by poor cohesion due to migration of the plasticizer are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of pressure-sensitive adhesives, in particular to a plasticizer-resistant acrylate pressure-sensitive adhesive. Background Art

[0002] Soft polyvinyl chloride (PVC) film has good elongation, tear strength, cold resistance, corrosion resistance, as well as excellent printability and low price. Therefore, the soft PVC pressure-sensitive tape (car body stickers, advertising stickers, etc.) prepared with it as the base material is widely used in the automotive, advertising, home appliances, home decoration and other industries.

[0003] However, soft PVC film contains a large amount 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, the small molecule plasticizers will slowly migrate to the interface between the substrate and the film or migrate into the film over time. This will cause the adhesion performance of the pressure-sensitive adhesive layer to be severely attenuated or the cohesion of the adhesive layer to be destroyed. Residual adhesive is likely to appear during peeling, which limits the application of soft PVC pressure-sensitive tapes. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] Therefore, the object of the present invention is to provide a plasticizer-resistant acrylic pressure-sensitive adhesive, which has good plasticizer resistance and will not leave residual adhesive when peeled off after aging, and has less attenuation of bonding performance.

[0006] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[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, multifunctional 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 of the plasticizer-resistant acrylic pressure-sensitive adhesive are as follows:

[0010] S1, mixing weighed soft monomers, hard monomers, polar monomers, and internal cross-linking monomers to obtain a mixed monomer;

[0011] S2, mixing part of the mixed monomer with part of the solvent, heating to 65-80° C. under an inert atmosphere, adding part of the initiator, and reacting at the reflux temperature of the solvent to obtain a reaction solution 1;

[0012] S3, adding the remaining mixed monomers, part of the solvent, and part of the initiator dropwise to the reaction solution 1, and reacting at the reflux temperature of the solvent to obtain the reaction solution 2;

[0013] S4, adding the remaining initiator to the reaction solution 2, and reacting at the solvent reflux temperature to obtain reaction solution 3;

[0014] S5. Cooling the reaction solution 3 to below 50° C., adding the remaining solvent and curing agent, and stirring to obtain a plasticizer-resistant acrylic pressure-sensitive adhesive.

[0015] As a preferred embodiment of the plasticizer-resistant acrylic 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 acrylic 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] As a preferred embodiment of the plasticizer-resistant acrylic 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 acrylic pressure-sensitive adhesive described in the present invention, the multifunctional acrylic ester monomer is at least one of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate and ditrimethylolpropane tetraacrylate.

[0019] As a preferred embodiment of the plasticizer-resistant acrylic pressure-sensitive adhesive of the present invention, the initiator is selected from at least one of azobisisobutyl cyanide, azobisisovaleronitrile, azobisisoheptylnitrile and dibenzoyl peroxide.

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

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

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. Through the synergistic effect of soft monomers, hard monomers, polar monomers and multifunctional acrylate monomers, when the prepared acrylate pressure-sensitive adhesive is used for soft PVC film, on the one hand, the compatibility of the high-polarity acrylate pressure-sensitive adhesive layer with the small molecular plasticizer in PVC becomes poor, and it is not easy for the plasticizer to migrate into the adhesive layer, and at the same time, the peeling force of the acrylate pressure-sensitive adhesive can be improved; on the other hand, the cohesion of the acrylate pressure-sensitive adhesive is further improved, and the residual adhesive phenomenon and the peeling force attenuation problem caused by the poor cohesion caused by the migration of plasticizers are reduced.

[0024] 2. Based on the fact that the polarity of small molecule plasticizers (DOP, DBP, etc.) in soft PVC films is relatively low, and according to the principle of like-compatibility, by introducing polar monomers into the system to improve the overall polarity of the acrylic pressure-sensitive adhesive, the compatibility of the acrylic pressure-sensitive adhesive with the plasticizer can be deteriorated, making it difficult for the plasticizer to migrate into the adhesive layer; at the same time, a higher content of polar groups (-CN, -CONH2, etc.) can improve the adhesion of the acrylic pressure-sensitive adhesive and reduce the peeling force attenuation problem caused by the migration of the plasticizer. At the same time, the present application also introduces multifunctional acrylic monomers (functionality ≥ 3) into the system to further improve the cohesion of the acrylic system and further improve the phenomenon of residual adhesive caused by poor cohesion due to the migration of the plasticizer.

[0025] 3. The present invention adopts a special preparation method, and heats to 65-80°C in an inert atmosphere to ensure that the influence of oxygen inhibition on the polymerization reaction can be reduced in a nitrogen atmosphere, making the polymerization reaction more stable. The dropwise addition method can better control the exothermicity of the polymerization reaction and the molecular weight. The initiator is added in multiple times. Because the initiator will be slowly consumed during the polymerization process, it is distributed and added to improve the monomer conversion rate, while controlling the molecular weight to ensure that the polymerization reaction is fully stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below in combination with the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0027] Figure 1 It is a schematic diagram of the test results of the plasticizer-resistant acrylic pressure-sensitive adhesives prepared in Examples 1-4 of the present invention and Comparative Examples 1-4. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0029] Secondly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

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

[0031] Acrylic pressure-sensitive adhesives in the prior art are usually synthesized by using as few long-chain acrylic monomers as possible, and using short-chain butyl acrylate and methyl acrylate as soft monomers to produce acrylic pressure-sensitive adhesives with poor compatibility with plasticizers, so that the plasticizer is not easy to migrate into the adhesive layer, thereby preventing the cohesive properties of the adhesive film from being reduced, and making it difficult to produce residual adhesive when peeling. However, the peeling force of the acrylic pressure-sensitive adhesive prepared by this method is relatively low, and the design of this method only considers the effect of the plasticizer on the cohesive properties of the adhesive layer, and does not consider the migration of the plasticizer leading to a decrease in the adhesive properties of the pressure-sensitive adhesive, that is, the attenuation of the peeling force. The attenuation of the peeling force will cause the soft PVC pressure-sensitive tape to warp, slip, and fall off during long-term use, affecting the use of the product.

[0032] Based on this, the plasticizer-resistant acrylic pressure-sensitive adhesive provided by the present application introduces polar monomers and multifunctional acrylic ester monomers into the system at the same time according to the characteristics of soft PVC, so as to make it difficult for the plasticizer to migrate into the adhesive layer by increasing the overall polarity of the acrylic pressure-sensitive adhesive, and improve the adhesion of the acrylic pressure-sensitive adhesive, while further improving the cohesion of the acrylic system and improving the phenomenon of residual adhesive. The plasticizer-resistant acrylic pressure-sensitive adhesive includes the following components by weight: soft monomer: 30-40 parts, hard monomer: 2-6 parts, polar monomer: 4-6 parts, multifunctional acrylic ester monomer: 0.01-0.1 parts, initiator: 0.1-0.3 parts, solvent: 55-65 parts, curing agent: 0.3-0.8 parts.

[0033] In order to ensure the cohesive force of the acrylic pressure-sensitive adhesive, the present application preferably uses at least one of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate and ditrimethylolpropane tetraacrylate as the multifunctional acrylic monomer; using these acrylic monomers with a functionality of ≥3 can obtain a higher degree of crosslinking than conventional internal crosslinking monomers (N-hydroxymethyl acrylamide or hydroxyethyl acrylamide, etc.), so that the cohesive strength of the acrylic pressure-sensitive adhesive is higher. At the same time, the multifunctional acrylic monomer forms a network crosslinking system during the polymerization process of the acrylic pressure-sensitive adhesive, which is more stable than conventional internal crosslinking monomers that also rely on the high-temperature crosslinking and curing of the product in the later stage.

[0034] In order to avoid or reduce the migration of small molecule plasticizers to the adhesive layer while taking into account the adhesion of the pressure-sensitive adhesive, the present application preferably selects at least one of acrylonitrile and acrylamide as the polar monomer. The polarity of the cyano group in acrylonitrile and the amide group in acrylamide is higher than that of the carboxyl group and the hydroxyl group. Therefore, the introduction of acrylonitrile or acrylamide can make the polarity of the acrylic ester pressure-sensitive adhesive higher, and can obtain higher adhesion while improving the plasticizer resistance.

[0035] In order to take into account the plasticizer resistance and adhesion of the acrylic pressure-sensitive adhesive, the present application preferably selects at least one of the soft monomers selected from n-butyl acrylate, isobutyl acrylate, and sec-butyl acrylate; the hard monomers are preferably selected from at least one of methyl acrylate, tert-butyl acrylate, and vinyl acetate; the initiator is preferably selected from at least one of azobisisobutyl cyanide, azobisisovaleronitrile, azobisisoheptonitrile, and dibenzoyl peroxide; the solvent is preferably selected from at least one of ethyl acetate, heptane, ethanol, isopropanol, and toluene; and the curing agent is preferably aluminum acetylacetonate-acetylacetone.

[0036] In order to verify the technical effect of the plasticizer-resistant acrylic pressure-sensitive adhesive of the present invention, the following Examples 1-4 and Comparative Examples 1-4 are provided.

[0037] Example 1

[0038] S1, 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 multifunctional acrylate monomer trimethylolpropane triacrylate are added into a 250 mL beaker and stirred to mix uniformly to obtain a mixed monomer;

[0039] S2, in a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, 25 parts by weight of the mixed monomers of step S1 and 30 parts by weight of ethyl acetate were added, and the mixture was replaced with nitrogen for 30 minutes, and then heated to 65°C in a constant temperature water bath, 0.02 parts by weight of azobisisobutylcyanide was completely dissolved in 1 part by weight of ethyl acetate and then added to the reaction bottle, and after the reaction was initiated, the solvent was refluxed stably, and the reaction was kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution 1;

[0040] S3, the remaining mixed monomers in step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyl cyanide were uniformly mixed, and the mixture was uniformly added dropwise to the reaction solution 1 in the reaction bottle using a constant pressure dropping funnel. The addition took 1 hour. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour to obtain the reaction solution 2;

[0041] S4, dissolving 0.02 parts by weight of azobisisobutyl cyanide in 4.6 parts by weight of ethyl acetate, and then adding the solution 2 in the reaction flask, and reacting at the reflux temperature of the solvent for 3 hours to obtain the solution 3;

[0042] S5. After the reaction is completed, the temperature is lowered to below 50° C., 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 acetylacetone are added and stirred evenly to obtain a plasticizer-resistant acrylic pressure-sensitive adhesive.

[0043] Example 2

[0044] S1, adding 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 multifunctional acrylate monomer trimethylolpropane trimethacrylate into a 250 mL beaker and stirring and mixing to obtain a mixed monomer;

[0045] S2, in a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, 27 parts by weight of the mixed monomers in step S1 and 27 parts by weight of heptane were added, and the mixture was replaced with nitrogen for 30 minutes, and then heated to 75°C in a constant temperature water bath, 0.03 parts by weight of azobisisoheptylcyanide was completely dissolved in 1 part by weight of ethyl acetate and then added to the reaction bottle, and after the reaction was initiated, the solvent was refluxed stably, and the reaction was kept at the solvent reflux temperature for 1 hour to obtain reaction solution 1;

[0046] S3, the remaining mixed monomers in step S1, 13.88 parts by weight of ethyl acetate, and 0.1 parts by weight of azobisisoheptylcyanide were uniformly mixed, and the mixture was uniformly added dropwise to the reaction solution 1 in the reaction bottle using a constant pressure dropping funnel. The addition took 1.5 hours. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour to obtain the reaction solution 2;

[0047] S4, dissolving 0.03 parts by weight of azobisisoheptylcyanide in 4.6 parts by weight of ethyl acetate, and then adding the solution 2 in the reaction flask, and reacting at the reflux temperature of the solvent for 4 hours to obtain the solution 3;

[0048] S5. After the reaction is completed, the temperature is lowered to below 50° C., 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 acetylacetone are added, and the mixture is stirred evenly to obtain a plasticizer-resistant acrylic pressure-sensitive adhesive.

[0049] Example 3

[0050] S1, 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 multifunctional acrylate monomer pentaerythritol triacrylate were added into a 250 mL beaker and stirred to mix uniformly to obtain a mixed monomer;

[0051] S2, in a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, 25 parts by weight of the mixed monomers of step S1, 20.5 parts by weight of ethyl acetate, and 10 parts by weight of heptane were added, and the mixture was replaced with nitrogen for 30 minutes, and then heated to 70°C in a constant temperature water bath, 0.03 parts by weight of azobisisovaleronitrile was completely dissolved in 1 part by weight of ethyl acetate and then added to the reaction bottle, and after the reaction was initiated, the solvent was stably refluxed, and the reaction was kept warm at the solvent reflux temperature for 0.5 hours to obtain reaction solution 1;

[0052] S3, the remaining mixed monomers in step S1, 10.8 parts by weight of ethyl acetate, and 0.12 parts by weight of diisocyanate were uniformly mixed, and the mixture was uniformly added dropwise to the reaction solution 1 in the reaction bottle using a constant pressure dropping funnel. The addition took 1 hour. After the addition was completed, the mixture was kept at the reflux temperature of the solvent for 1.5 hours to obtain the reaction solution 2;

[0053] S4, dissolving 0.02 parts by weight of azobisisovaleronitrile in 4.6 parts by weight of ethyl acetate, and then adding the solution 2 in the reaction flask, and reacting at the reflux temperature of the solvent for 2.5 hours to obtain the solution 3;

[0054] S5. After the reaction is completed, the temperature is lowered to below 50° C., 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 acetylacetone are added, and the mixture is stirred evenly to obtain a plasticizer-resistant acrylic pressure-sensitive adhesive.

[0055] Example 4

[0056] S1, adding 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 multifunctional acrylate monomer ditrimethylolpropane tetraacrylate into a 250 mL beaker and stirring and mixing to obtain a mixed monomer;

[0057] S2, in a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, 25 parts by weight of the mixed monomers of step S1 and 30 parts by weight of ethyl acetate were added, and the mixture was replaced with nitrogen for 30 minutes, and then heated to 65°C in a constant temperature water bath, 0.02 parts by weight of azobisisobutylcyanide was completely dissolved in 1 part by weight of ethyl acetate and then added to the reaction bottle, and after the reaction was initiated, the solvent was refluxed stably, and the reaction was kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution 1;

[0058] S3, the remaining mixed monomers in step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyl cyanide were uniformly mixed, and the mixture was uniformly added dropwise to the reaction solution 1 in the reaction bottle using a constant pressure dropping funnel. The addition took 1 hour. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour to obtain the reaction solution 2;

[0059] S4, dissolving 0.02 parts by weight of azobisisobutyl cyanide in 4.6 parts by weight of ethyl acetate, and then adding the solution 2 in the reaction flask, and reacting at the reflux temperature of the solvent for 3 hours to obtain the solution 3;

[0060] S5. After the reaction is completed, the temperature is lowered to below 50° C., 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 acetylacetone are added and stirred evenly to obtain a plasticizer-resistant acrylic pressure-sensitive adhesive.

[0061] Comparative Example 1

[0062] S1, adding 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 into a 250 mL beaker, stirring and mixing to obtain a mixed monomer;

[0063] S2, in a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, 25 parts by weight of the mixed monomers of step S1 and 30 parts by weight of ethyl acetate were added, and the mixture was replaced with nitrogen for 30 minutes, and then heated to 65°C in a constant temperature water bath, 0.02 parts by weight of azobisisobutylcyanide was completely dissolved in 1 part by weight of ethyl acetate and then added to the reaction bottle, and after the reaction was initiated, the solvent was refluxed stably, and the reaction was kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution 1;

[0064] S3, the remaining mixed monomers in step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyl cyanide were uniformly mixed, and the mixture was uniformly added dropwise to the reaction solution 1 in the reaction bottle using a constant pressure dropping funnel. The addition took 1 hour. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour to obtain the reaction solution 2;

[0065] S4, dissolving 0.02 parts by weight of azobisisobutyl cyanide in 4.6 parts by weight of ethyl acetate, and then adding the solution 2 in the reaction flask, and reacting at the reflux temperature of the solvent for 3 hours to obtain the solution 3;

[0066] S5. After the reaction is completed, the temperature is lowered to below 50° C., 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 acetylacetone are added and stirred evenly to obtain a plasticizer-resistant acrylic pressure-sensitive adhesive.

[0067] The difference between this comparative example and Example 1 is that no multifunctional acrylate monomer is added to the system.

[0068] Comparative Example 2

[0069] S1, put 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-hydroxymethyl acrylamide into a 250 mL beaker and stir to mix uniformly to obtain a mixed monomer;

[0070] S2, in a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, 25 parts by weight of the mixed monomers of step S1 and 30 parts by weight of ethyl acetate were added, and the mixture was replaced with nitrogen for 30 minutes, and then heated to 65°C in a constant temperature water bath, 0.02 parts by weight of azobisisobutylcyanide was completely dissolved in 1 part by weight of ethyl acetate and then added to the reaction bottle, and after the reaction was initiated, the solvent was refluxed stably, and the reaction was kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution 1;

[0071] S3, the remaining mixed monomers in step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyl cyanide were uniformly mixed, and the mixture was uniformly added dropwise to the reaction solution 1 in the reaction bottle using a constant pressure dropping funnel. The addition took 1 hour. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour to obtain the reaction solution 2;

[0072] S4, dissolving 0.02 parts by weight of azobisisobutyl cyanide in 4.6 parts by weight of ethyl acetate, and then adding the solution 2 in the reaction flask, and reacting at the reflux temperature of the solvent for 3 hours to obtain the solution 3;

[0073] S5. After the reaction is completed, the temperature is lowered to below 50° C., 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 acetylacetone are added and stirred evenly to obtain a plasticizer-resistant acrylic pressure-sensitive adhesive.

[0074] The difference between this comparative example and Example 1 is that trimethylolpropane triacrylate in the system is replaced by N-hydroxymethyl acrylamide.

[0075] Comparative Example 3

[0076] S1, 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 multifunctional acrylate monomer trimethylolpropane triacrylate are added into a 250 mL beaker and stirred to mix evenly to obtain a mixed monomer;

[0077] S2, in a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, 25 parts by weight of the mixed monomers of step S1 and 30 parts by weight of ethyl acetate were added, and the mixture was replaced with nitrogen for 30 minutes, and then heated to 65°C in a constant temperature water bath, 0.02 parts by weight of azobisisobutylcyanide was completely dissolved in 1 part by weight of ethyl acetate and then added to the reaction bottle, and after the reaction was initiated, the solvent was refluxed stably, and the reaction was kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution 1;

[0078] S3, the remaining mixed monomers in step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyl cyanide were uniformly mixed, and the mixture was uniformly added dropwise to the reaction solution 1 in the reaction bottle using a constant pressure dropping funnel. The addition took 1 hour. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour to obtain the reaction solution 2;

[0079] S4, dissolving 0.02 parts by weight of azobisisobutyl cyanide in 4.6 parts by weight of ethyl acetate, and then adding the solution 2 in the reaction flask, and reacting at the reflux temperature of the solvent for 3 hours to obtain the solution 3;

[0080] S5. After the reaction is completed, the temperature is lowered to below 50° C., 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 acetylacetone are added and stirred evenly to obtain a plasticizer-resistant acrylic pressure-sensitive adhesive.

[0081] The difference between this comparative example and Example 1 is that no polar monomer is added to the system.

[0082] Comparative Example 4

[0083] S1, 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 multifunctional acrylate monomer trimethylolpropane triacrylate are added into a 250 mL beaker and stirred to mix evenly to obtain a mixed monomer;

[0084] S2, in a 1L four-necked flask equipped with a stirring paddle, a thermometer, and a reflux condenser, 25 parts by weight of the mixed monomers of step S1 and 30 parts by weight of ethyl acetate were added, and the mixture was replaced with nitrogen for 30 minutes, and then heated to 65°C in a constant temperature water bath, 0.02 parts by weight of azobisisobutylcyanide was completely dissolved in 1 part by weight of ethyl acetate and then added to the reaction bottle, and after the reaction was initiated, the solvent was refluxed stably, and the reaction was kept at the solvent reflux temperature for 0.5 hours to obtain reaction solution 1;

[0085] S3, the remaining mixed monomers in step S1, 11.36 parts by weight of ethyl acetate, and 0.09 parts by weight of azobisisobutyl cyanide were uniformly mixed, and the mixture was uniformly added dropwise to the reaction solution 1 in the reaction bottle using a constant pressure dropping funnel. The addition took 1 hour. After the addition was completed, the mixture was kept at the solvent reflux temperature for 1 hour to obtain the reaction solution 2;

[0086] S4, dissolving 0.02 parts by weight of azobisisobutyl cyanide in 4.6 parts by weight of ethyl acetate, and then adding the solution 2 in the reaction flask, and reacting at the reflux temperature of the solvent for 3 hours to obtain the solution 3;

[0087] S5. After the reaction is completed, the temperature is lowered to below 50° C., 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 acetylacetone are added and stirred evenly to obtain a plasticizer-resistant acrylic pressure-sensitive adhesive.

[0088] The difference between this comparative example and Example 1 is that acrylic acid is used instead of acrylonitrile, a polar monomer.

[0089] The plasticizer-resistant acrylic pressure-sensitive adhesive prepared in the above embodiments and comparative examples was evenly coated on the release paper using a scraper, baked at 120°C for 2 min, and then transferred to a 90 μm soft PVC substrate to obtain a soft PVC pressure-sensitive adhesive tape sample with a dry adhesive thickness of 25 μm. Finally, the sample was aged at 40°C for 3 days before performance testing.

[0090] The plasticizer-resistant acrylic pressure-sensitive adhesive prepared in the above embodiments and comparative examples was evenly coated on the release paper using a scraper, baked at 120°C for 2 min, and then transferred to a 90 μm soft PVC substrate to obtain a soft PVC pressure-sensitive adhesive tape sample with a dry adhesive thickness of 25 μm. Finally, the sample was aged at 40°C for 3 days before performance testing.

[0091] The test results are as follows Figure 1 As shown, it can be seen from the test results that the plasticizer-resistant acrylic pressure-sensitive adhesive prepared in each embodiment of the present invention has good plasticizer resistance. The use of high-polarity monomers to introduce a higher content of polar groups to increase the polarity of acrylic esters has a significant effect on resisting the migration of plasticizers. The prepared PVC tape has a peeling force attenuation of no more than 10% after aging at high temperature and high humidity. At the same time, the use of multifunctional acrylic ester monomers further improves the cohesion of acrylic esters, and there will be no residual adhesive when peeling after aging, and the effect is better than that of conventional internal cross-linking monomers.

[0092] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. 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: The composition by weight is as follows: Soft monomer: 30-40 parts, hard monomer: 2-6 parts, polar monomer: 4-6 parts, multifunctional 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 specific preparation steps of the plasticizer-resistant acrylic pressure-sensitive adhesive are as follows: S1, mixing weighed soft monomers, hard monomers, polar monomers, and internal cross-linking monomers to obtain a mixed monomer; S2, mixing part of the mixed monomer with part of the solvent, heating to 65-80° C. under an inert atmosphere, adding part of the initiator, and reacting at the reflux temperature of the solvent to obtain a reaction solution 1; S3, adding the remaining mixed monomers, part of the solvent, and part of the initiator dropwise to the reaction solution 1, and reacting at the reflux temperature of the solvent to obtain the reaction solution 2; S4, adding the remaining initiator to the reaction solution 2, and reacting at the solvent reflux temperature to obtain a reaction solution 3; S5. Cooling the reaction solution 3 to below 50° C., adding the remaining solvent and curing agent, and stirring to obtain a plasticizer-resistant acrylic 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 polar monomer is at least one of acrylonitrile and acrylamide.

5. The plasticizer-resistant acrylic pressure-sensitive adhesive according to claim 1, characterized in that: The multifunctional acrylate monomer is at least one of trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate and ditrimethylolpropane tetraacrylate.

6. The plasticizer-resistant acrylate pressure-sensitive adhesive according to claim 1, characterized in that: The initiator is selected from at least one of azobisisobutyl cyanide, azobisisovaleronitrile, azobisisoheptanenitrile and dibenzoyl peroxide.

7. 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.

8. The plasticizer-resistant acrylate pressure-sensitive adhesive according to claim 1, characterized in that: The curing agent is aluminum acetylacetonate-acetylacetone.

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