Plasticizer-resistant pressure-sensitive adhesive, adhesive tape, preparation method and application

Abstract

The invention relates to a plasticizer-resistant pressure-sensitive adhesive, an adhesive tape as well as a preparation method and application. The plasticizer-resistant pressure-sensitive adhesive is prepared from the following components in parts by mass: 100 parts of an acrylate polymer solution in terms of solid, 5-30 parts of tackifying resin, 1-15 parts of porous micron particles and 0.1-10 parts of a curing agent, wherein the acrylate polymer solution is obtained by polymerizing a soft monomer, a hard monomer and a functional monomer in the presence of a solvent, an initiator and a chain transfer agent; the mass of the soft monomer accounts for 80%-95% of the total mass of the soft monomer, the hard monomer and the functional monomer, and the mass of alkyl acrylate with the alkyl carbon atom number larger than 4 in the soft monomer accounts for not higher than 25% of the total mass of the soft monomer, the hard monomer and the functional monomer; the mass of the functional monomer accounts for more than 0% and less than or equal to 10% of the total mass of the soft monomer, the hard monomer and the functional monomer. The plasticizer-resistant pressure-sensitive adhesive can be used for PVC bonding, has good initial stripping force, and can maintain good bonding performance for a long time.

Description

Technical Field

[0001] This invention relates to the field of adhesives, specifically to a plasticizer-resistant pressure-sensitive adhesive, tape, preparation method, and application. Background Technology

[0002] Polyvinyl chloride (PVC), a general-purpose plastic with high production volume, low cost, and excellent overall performance, is widely used in building decoration, medical devices, automotive interiors, packaging materials, wires and cables, and daily necessities. Based on the amount of plasticizer added, PVC can be divided into two main categories: rigid PVC and flexible PVC. Flexible PVC typically contains 20%-50% plasticizers (such as phthalates, epoxy resins, and phosphate esters). These plasticizers impart flexibility, plasticity, and low-temperature performance to the material by weakening the intermolecular forces between polymer chains. However, the large amount of plasticizers present in flexible PVC poses a significant challenge to adhesive applications.

[0003] During the bonding process and under long-term use, plasticizers gradually migrate and penetrate into the adhesive layer, leading to problems such as plasticization and softening of the adhesive layer, interface damage, and accelerated aging. While traditional acrylic pressure-sensitive adhesives offer advantages such as high transparency and good weather resistance, their molecular structure is highly sensitive to plasticizers, resulting in insufficient resistance to migration and making it difficult to meet the long-term reliable bonding requirements of flexible PVC. Currently, methods to improve the plasticizer resistance of pressure-sensitive adhesives mainly include chemical modification and physical blending.

[0004] Chemical modification involves introducing polar monomers (such as those containing carboxyl, hydroxyl, or amide groups) to enhance intermolecular forces or using crosslinking techniques to increase network density. However, chemical modification methods are typically complex, and the newly synthesized substances are often intricate and costly. For example, patent application CN117004349A achieves excellent plasticizer resistance by adding the polar monomer methyl methacrylate (MA) and increasing crosslinking density, but the higher polarity and crosslinking density sacrifice the adhesive properties of the pressure-sensitive adhesive, resulting in poor adhesion. Patent application CN119874525A achieves plasticizer blocking through a specially synthesized hyperbranched polyester-modified acrylic acid, while CN116285784A introduces polyurethane and polyurea structures through chemical synthesis. The dense hydrogen bonds formed by these structures improve plasticizer resistance. The above-mentioned prior art involves complex synthesis steps for the hyperbranched polyester-modified acrylic acid precursor and the polyurethane and polyurea acrylates, resulting in high costs.

[0005] Physical blending achieves plasticizer barrier properties by adding inorganic nanoparticles and organic fillers. While the physical blending process is simple, a considerable amount needs to be added to achieve plasticizer resistance, and there are issues with dispersibility with the pressure-sensitive adhesive matrix, resulting in poorer initial tack and reduced peel strength. For example, patent application CN112126389A uses microphase separation (physical crosslinking) generated by acrylic block copolymers in the formulation to inhibit plasticizer diffusion, but this pressure-sensitive adhesive has weak peel strength. Patent CN116285784A uses kaolin and bamboo fiber, two inorganic and organic additives, to form barrier zones to inhibit plasticizer diffusion; however, due to the modulus-enhancing effect of fillers on the material, this tape requires heat-melting softening before application and cannot be bonded at room temperature.

[0006] In summary, whether pressure-sensitive adhesives are chemically modified or physically blended, the modified / blended adhesives suffer from increased modulus and decreased initial tack. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the first objective of the present invention is to provide a plasticizer-resistant pressure-sensitive adhesive that can be used for bonding PVC, prevents plasticizer migration and plasticization of the pressure-sensitive adhesive, has good initial peel strength, and can maintain good bonding performance over a long period of time.

[0008] A second objective of this invention is to provide a method for preparing the plasticizer-resistant pressure-sensitive adhesive.

[0009] A third objective of this invention is to provide a tape using the plasticizer-resistant pressure-sensitive adhesive.

[0010] A fourth objective of this invention is to provide a method for preparing the tape.

[0011] A fifth objective of this invention is to provide the application of the plasticizer-resistant pressure-sensitive adhesive or the tape.

[0012] To achieve the first objective of this invention, a plasticizer-resistant pressure-sensitive adhesive is provided, prepared from the following components in parts by weight: 100 parts of acrylate polymer solution (solids), 5-30 parts of tackifying resin, 1-15 parts of porous micron particles, and 0.1-10 parts of curing agent; wherein the acrylate polymer solution is obtained by polymerizing soft monomers, hard monomers, and functional monomers in the presence of a solvent, an initiator, and a chain transfer agent; the mass of the soft monomers accounts for 80%-95% of the total mass of the soft monomers, hard monomers, and functional monomers, and the mass of alkyl acrylates with more than 4 alkyl carbon atoms in the soft monomers accounts for no more than 25% of the total mass of the soft monomers, hard monomers, and functional monomers; the mass of the hard monomers accounts for 0%-15% of the total mass of the soft monomers, hard monomers, and functional monomers, and the mass of the hard monomers accounts for more than 0% and less than or equal to 10% of the total mass of the soft monomers, hard monomers, and functional monomers.

[0013] In some embodiments of the present invention, the soft monomer is at least one of n-butyl acrylate and isobutyl acrylate, or the soft monomer is a mixture of at least one of n-butyl acrylate and isobutyl acrylate and at least one of 2-ethylhexyl acrylate and isooctyl acrylate.

[0014] In some embodiments of the present invention, the hard monomer is at least one selected from methyl methacrylate, ethyl methacrylate, styrene, vinyl acetate, and vinyl acetate.

[0015] In some embodiments of the present invention, the functional monomer is at least one selected from acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, and β-carboxyethyl acrylate.

[0016] In some embodiments of the present invention, the soft monomer is a mixture of n-butyl acrylate and isooctyl acrylate, wherein the mass of isooctyl acrylate accounts for more than 0% and less than or equal to 25% of the total mass of n-butyl acrylate and isooctyl acrylate.

[0017] In some embodiments of the present invention, the functional monomer contains β-carboxyethyl acrylate, wherein the mass of β-carboxyethyl acrylate accounts for more than 0% and less than or equal to 75% of the total mass of the functional monomer.

[0018] In some embodiments of the present invention, the acrylate polymer solution is obtained by solution polymerization of soft monomers, hard monomers and functional monomers in an organic solvent, wherein the mass of the organic solvent accounts for 30% to 70% of the mass of the acrylate polymer solution, and the organic solvent is at least one of ethyl acetate, toluene and acetone.

[0019] In some embodiments of the present invention, the initiator is 0.1% to 2% of the total mass of the soft monomer, hard monomer and functional monomer, and the initiator is at least one of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide.

[0020] In some embodiments of the present invention, the chain transfer agent is 0.01% to 1% of the total mass of the soft monomer, hard monomer and functional monomer, and the chain transfer agent is n-dodecyl mercaptan.

[0021] In some embodiments of the present invention, the weight-average molecular weight of the acrylate copolymer obtained by polymerizing the soft monomer, hard monomer and functional monomer is 400 kg / mol to 700 kg / mol.

[0022] In some embodiments of the present invention, the particle size of the porous micron particles is 1 μm to 50 μm.

[0023] In some embodiments of the present invention, the tackifying resin is at least one of terpene phenol, modified rosin, and polymerized rosin.

[0024] In some embodiments of the present invention, the curing agent is at least one of the following: polyisocyanate toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, hydrogenated xylene diisocyanate, HDI trimer, metal chelate, epoxy compound, and aziridine.

[0025] In some embodiments of the present invention, the plasticizer-resistant pressure-sensitive adhesive compound also includes a diluent, the mass of which is 0% to 50% of the acrylate polymer solution.

[0026] To achieve the second objective of this invention, this invention provides a method for preparing a plasticizer-resistant pressure-sensitive adhesive as described in any of the above embodiments, comprising the following steps: adding tackifying resin, porous micron particles and a portion of diluent to an acrylate polymer solution, stirring and dispersing the mixture at room temperature or below 50°C to form a homogeneous mixture; adding a curing agent at room temperature, stirring evenly, and then coating, curing and die-cutting to obtain a pressure-sensitive adhesive tape.

[0027] In some embodiments of the present invention, the preparation method of the acrylate polymer solution includes the following steps: mixing soft monomers, hard monomers, functional monomers and organic solvents uniformly to obtain a mixed solution; adding a portion of the mixed solution to a reaction vessel equipped with a stirrer, nitrogen pipeline, condenser, thermometer and dropping device; loading the remaining portion of the mixed solution into the dropping device; heating the mixed solution in the reaction vessel to a specific temperature of 61 ℃ to 66 ℃, continuously introducing nitrogen gas, stirring, adding a first portion of initiator, and controlling the temperature at 61 ℃ to 66 ℃ for 0 to 2 hours of reaction; gradually adding the mixed solution from the dropping device dropwise during 3 to 5 hours of reaction, and adding a second portion of initiator, controlling the temperature at 66 ℃ to 70 ℃; reacting for 6 hours, adding the remaining initiator and raising the temperature to above 76 ℃, maintaining this temperature until the 8th hour, at which point adding solvent for dilution, and ending the reaction; cooling the reaction system to below 40 ℃ to obtain the acrylate polymer solution.

[0028] To achieve the third objective of the present invention, the present invention provides an adhesive tape comprising a substrate and an adhesive layer disposed on the substrate, the adhesive layer being made of pressure-sensitive adhesive as described in any of the above embodiments.

[0029] To achieve the fourth objective of this invention, this invention provides a method for preparing the above-mentioned adhesive tape, comprising the following steps: uniformly coating a pressure-sensitive adhesive solution onto a surface of a substrate by means of doctor blade coating, roller coating, or comma coating, wherein the substrate is a PET film, PI film, BOPP film, or release film; sending the coated adhesive layer into an oven and drying it at 50℃~60℃ for 1 minute to 5 minutes to remove solvent, and then placing it in an oven at 80℃~100℃ for 1 minute to 5 minutes to further remove solvent and residual monomers; subsequently curing the coated tape at 50℃~60℃ for 24 hours to 48 hours to allow the curing agent to react completely, thereby obtaining the adhesive tape.

[0030] To achieve the fifth objective of this invention, this invention provides an adhesive composite material comprising PVC and an adhesive layer disposed on the surface of the PVC, the adhesive layer being formed from the aforementioned pressure-sensitive adhesive or tape.

[0031] Compared with the prior art, the present invention can achieve the following beneficial effects: The plasticizer-resistant pressure-sensitive adhesive and tape of this invention possess excellent plasticizer resistance. Utilizing porous micron-sized particles as "molecular sponges," these particles actively adsorb and immobilize migrating plasticizers, physically blocking their plasticizing effect. Furthermore, these particles act as physical anchors, enhancing the adhesive's resistance to plasticization and ensuring the tape maintains high holding power and cohesive strength on difficult-to-bond substrates such as PVC for extended periods. Through acrylate polymer chain design and appropriate chemical crosslinking, the adhesive maintains excellent initial tack, peel strength, and flexibility, avoiding the increased brittleness caused by simply increasing crosslinking density. The use of a certain amount of tackifying resin further inhibits plasticizer migration. This novel plasticizer-resistant acrylate pressure-sensitive adhesive solves the plasticizer migration problem in flexible PVC bonding, providing a high-performance, easy-to-process, and widely applicable pressure-sensitive adhesive solution. Detailed Implementation

[0032] The present invention provides a plasticizer-resistant pressure-sensitive adhesive, which is suitable for bonding materials containing plasticizers, such as PVC, polyolefins, PVB, and rubber. It is especially suitable for materials with high plasticizer content, such as soft PVC. This invention solves the contradiction between the plasticizer resistance and initial tack and bonding performance of existing pressure-sensitive adhesives that often occurs in the chemical modification and physical blending of existing pressure-sensitive adhesives.

[0033] One solution to the problems of existing technologies is to use organic fillers with porous structures. As a type of organic filler, porous microspheres, as a novel functional material, possess unique characteristics such as a porous structure, low density, and high specific surface area. They have shown potential in coatings, adhesives, and other fields, including improving mechanical properties, regulating density, and enhancing thermal and sound insulation. Introducing porous microspheres into acrylic pressure-sensitive adhesive systems not only maintains appropriate flexibility and initial tack of the adhesive layer, but their porous structure can also effectively adsorb and accommodate migrating plasticizers, reducing the plasticizing effect of plasticizers on the continuous phase of the adhesive layer, thereby significantly improving plasticizer resistance.

[0034] Specifically, the plasticizer-resistant pressure-sensitive adhesive of the present invention comprises, by weight, 100 parts of acrylate polymer solution (solids), 5 to 30 parts of tackifying resin, 1 to 15 parts of porous micron particles, and 0.1 to 10 parts of curing agent.

[0035] The acrylate polymer solution mainly consists of acrylate polymer and organic solvent, with the acrylate polymer dispersed in the organic solvent to obtain the acrylate polymer solution.

[0036] The acrylate polymer solution is obtained by polymerizing soft monomers, hard monomers and functional monomers in the presence of solvent, initiator and chain transfer agent. The initiator is used to initiate free radical copolymerization of monomers, and the chain transfer agent is used to control the molecular weight of the acrylate polymer to avoid the molecular weight being too high and affecting the subsequent dispersion of porous micron particles.

[0037] Soft monomers are monomers whose glass transition temperature (Tg) of the polymer itself is less than -25°C. The mass of soft monomers accounts for 80% to 95% of the total mass of soft monomers, hard monomers, and functional monomers; for example, it can be 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, etc. Soft monomers are used in larger quantities, and their role is to lower the glass transition temperature and modulus of the pressure-sensitive adhesive, enabling it to possess the necessary pressure sensitivity and flexibility within its operating temperature range (generally -20°C to 60°C).

[0038] The mass of alkyl acrylates with more than 4 alkyl carbon atoms in the soft monomer shall not exceed 25% of the total mass of the soft monomer, hard monomer, and functional monomer. Alkyl acrylates with more than 4 alkyl carbon atoms have low polarity, and their excessive content is detrimental to plasticizer resistance. Therefore, their content is limited to no more than 20% of the total monomer mass, for example, it can be 0% to 20%, such as 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc.

[0039] Hard monomers are monomers whose glass transition temperature (Tg) of their polymer is greater than 20°C. The mass of hard monomers accounts for 0% to 15% of the total mass of soft monomers, hard monomers, and functional monomers, for example, 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc., preferably greater than 0 and less than or equal to 15%. Hard monomers provide cohesive strength and rigidity, and work together with soft monomers to regulate the glass transition temperature, modulus, and viscoelasticity of the copolymer. Furthermore, due to their higher polarity compared to soft monomers, hard monomers can provide a certain degree of plasticizer resistance.

[0040] The role of functional monomers is to provide crosslinking sites and react with curing agents. Functional monomers may contain hydroxyl or carboxyl groups. The mass of functional monomers accounts for more than 0% and less than or equal to 10% of the total mass of soft monomers, hard monomers, and functional monomers, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc. Functional monomers can enhance cohesion to a certain extent, stabilize and disperse porous micron-sized particles through interfacial interactions, and the hydrogen bonds contained in their structure can also provide a certain degree of barrier effect against plasticizers.

[0041] Porous micron-sized particles are micron-sized microparticles with a porous structure. On the one hand, they lock migrating plasticizers within the pores of the particles, thus preventing them from interacting with the acrylate polymer molecular chains. On the other hand, they act as physical anchors, enhancing the anti-plasticization ability of the pressure-sensitive adhesive (PSA). This significantly delays the plasticizing effect of plasticizers on the acrylate PSA network, maintaining the PSA's cohesion and modulus, while preserving excellent adhesion and processing adaptability. The PSA is composed of 1 to 15 parts of porous micron-sized particles relative to 100 parts of the acrylate polymer solution (solids only), for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 parts.

[0042] Tackifying resins can improve the adhesive properties of pressure-sensitive adhesives and prevent plasticizers from migrating into the adhesive. The tackifying resin is present in quantities of 5 to 30 parts per 100 parts (solids) of the acrylate polymer solution, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30 parts.

[0043] The curing agent reacts with the functional monomer groups of the acrylate polymer to form a three-dimensional cross-linked structure, thereby enhancing the barrier effect of the pressure-sensitive adhesive on plasticizers. The amount of curing agent used is 0.1 to 10 parts per 100 parts of the acrylate polymer solution (based on solids), for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 parts.

[0044] As can be seen from the above, the embodiments of the present invention provide a plasticizer-resistant acrylate pressure-sensitive adhesive based on porous micron particles. Through the physical adsorption and physical anchoring of the blended porous microparticles, the cross-linking structure and polarity control of the polyacrylate raw material itself, and the physical barrier of the tackifying resin, the synergistic effect of multiple components achieves the effect of plasticizer resistance.

[0045] In some examples, the soft monomer is at least one of n-butyl acrylate and isobutyl acrylate, or the soft monomer is a mixture of at least one of n-butyl acrylate and isobutyl acrylate and at least one of 2-ethylhexyl acrylate and isooctyl acrylate. Soft monomers with fewer alkyl carbon atoms, such as n-butyl acrylate and isobutyl acrylate, are more polar than soft monomers with more carbon atoms, such as n-butyl acrylate and isobutyl acrylate. Therefore, the presence of a certain amount of n-butyl acrylate and isobutyl acrylate in the soft monomer is beneficial for improving the solvent resistance of the pressure-sensitive adhesive.

[0046] In some examples, the hard monomer is at least one of methyl methacrylate, ethyl methacrylate, styrene, vinyl acetate, and vinyl acetate.

[0047] In some examples, the functional monomer is at least one of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, and β-carboxyethyl acrylate.

[0048] In some examples, the soft monomer is a mixture of n-butyl acrylate and isooctyl acrylate, wherein the mass of isooctyl acrylate accounts for more than 0% and less than or equal to 23% of the total mass of n-butyl acrylate and isooctyl acrylate, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, etc. The presence of a small amount of isooctyl acrylate in the soft monomer is beneficial for improving the initial peel strength.

[0049] In some examples, the functional monomer contains β-carboxyethyl acrylate. β-carboxyethyl acrylate has a higher carboxyl content but better flexibility, resulting in a lower modulus of the tape, which is beneficial for wetting during bonding. β-carboxyethyl acrylate constitutes more than 0% and less than or equal to 75% of the functional monomer content, which helps improve initial peel strength without affecting plasticizer resistance. In some examples, the functional monomer is a mixture of acrylic acid, β-carboxyethyl acrylate, and hydroxyethyl 2-acrylate. The mass percentage of β-carboxyethyl acrylate is more than 0% and less than or equal to 75% of the total mass of acrylic acid, β-carboxyethyl acrylate, and hydroxyethyl 2-acrylate, and the mass percentage of hydroxyethyl 2-acrylate is more than 0% and less than or equal to 1% of the total mass of acrylic acid, β-carboxyethyl acrylate, and hydroxyethyl 2-acrylate.

[0050] In some examples, the acrylate polymer solution is obtained by solution polymerization of soft monomers, hard monomers, and functional monomers in an organic solvent. The organic solvent accounts for 30% to 70% of the mass of the acrylate polymer solution, and correspondingly, the solid content of the acrylate polymer solution can be 30% to 70%. The organic solvent is at least one of ethyl acetate, toluene, and acetone. The acrylate polymer solution is prepared by classical solution free radical copolymerization, a method based on mature solution polymerization technology that requires no complex equipment modification.

[0051] In some examples, the mass ratio of soft monomers, hard monomers, and functional monomers is (86~89):6:(5~8), which gives the resulting copolymers suitable glass transition temperature, modulus, viscoelasticity, and crosslinking sites, which is beneficial for balancing adhesive properties and plasticizer resistance.

[0052] In some examples, the initiator is 0.1% to 2% of the total mass of the soft monomer, hard monomer, and functional monomer, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, etc. The initiator is at least one of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide. Its function is to initiate free radical reactions, and it can be added stepwise, fractionally, or in groups at various stages of the reaction. The initiation temperature can be between 60℃ and 80℃.

[0053] In some examples, the chain transfer agent is 0.01% to 1% of the total mass of the soft monomer, hard monomer, and functional monomer, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc. The chain transfer agent can be n-dodecyl mercaptan.

[0054] In some examples, the weight-average molecular weight of the acrylate copolymers obtained by polymerizing soft monomers, hard monomers and functional monomers is 400 kg / mol to 700 kg / mol, for example 430 kg / mol to 560 kg / mol. The small molecular weight of the acrylate copolymers is beneficial for the dispersion of porous micron particles.

[0055] In some examples, the porous microparticles have a particle size of 1 μm to 50 μm, for example, 7 μm. The porous microparticles can be MR-7GPP porous polymethyl methacrylate microspheres produced by Zongyan Chemical (Suzhou) Co., Ltd.

[0056] In some examples, the tackifying resin is at least one of terpene phenols, modified rosin, and polymerized rosin. These resins are high softening point resins with a certain degree of polarity, hydroxyl or carboxyl groups, which helps to improve the adhesion, temperature resistance, and plasticizer resistance of the pressure-sensitive adhesive. Preferably, a mixture of multiple tackifying resins, such as a mixture of terpene phenols and modified rosin, can better adjust the modulus.

[0057] In some examples, the curing agent is at least one of the following: toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, hydrogenated xylene diisocyanate, HDI trimer, metal chelate (such as aluminum acetylacetonate), epoxy compound (such as organosilicon epoxy compound), and aziridine. The curing agent is used to form a moderately cross-linked network, further improving the heat resistance, solvent resistance, and plasticizer penetration resistance of the adhesive layer.

[0058] In some examples, plasticizer-resistant pressure-sensitive adhesives also include a diluent, with the diluent's mass being 0% to 50% of the acrylate polymer solution. Its main function is to adjust the solids content and viscosity of the formulation, providing favorable viscosity and solids conditions for stable coating. The diluent can be, for example, ethyl acetate.

[0059] In some examples, the mass ratio of acrylate polymer solution (on a solids basis), tackifying resin, porous micron particles, and curing agent is 100:(15~20):(3~5):(0.3~0.5), for example 100:20:(3~5):0.3.

[0060] In some examples, the preparation method of embodiments of the present invention includes the following steps: Part 1: Preparation of Acrylic Polymer Solution Ingredients: Weigh the soft monomer, hard monomer, and functional monomer and solvent according to the above proportions, and mix them evenly to obtain a mixed solvent. Then, add half of this mixed solvent to a reaction vessel equipped with a stirrer, nitrogen line, condenser, thermometer, and dropping device. The remaining half is placed in a constant pressure funnel and added dropwise during the reaction.

[0061] Polymerization reaction: The solution in the reactor is heated to a specific temperature of 61-66°C, and nitrogen gas is purged for half an hour. After nitrogen purging is complete, one-third of the initiator is added to begin the reaction. The temperature is controlled at 61-66°C for the first 0-2 hours. From the 3rd to 5th hour of the reaction, the remaining half of the monomer / solvent mixture is gradually added dropwise, along with one-third of the initiator, maintaining a stable temperature of 66-70°C. After 6 hours of reaction, the remaining one-third of the initiator is added, and the temperature is raised to above 76°C. This temperature is maintained until the 8th hour, at which point an appropriate amount of solvent is added to terminate the reaction. At this point, the monomer conversion rate reaches over 98%.

[0062] Cooling and discharging: Cool the reaction system to below 40°C to obtain an acrylate polymer solution with a solid content of 30-60%, which is then ready for use.

[0063] Part Two: Compounding of Pressure-Sensitive Adhesives Compounding: To the prepared acrylate polymer solution (100 parts, based on solids) mentioned above, add measured amounts of tackifying resin (such as rosin resin, terpene resin, petroleum resin), porous micron-sized particles, and a portion of diluent in sequence. At room temperature or with moderate heating (<50°C), thoroughly disperse and mix using a variable-speed stirrer until the particles are uniformly dispersed, forming a homogeneous mixture.

[0064] Adding curing agent: Cool the system temperature to room temperature (25±5°C), add the measured amount of curing agent, and stir quickly until homogeneous.

[0065] Part Three: Tape Preparation Coating and Curing: The prepared pressure-sensitive adhesive is evenly coated onto the substrate (such as PET film, PI film, BOPP film, release film, release paper, etc.) using methods such as doctor blade coating, roller coating, or comma coating. Depending on the specific application, double-sided adhesives with a thickness of 10-100μm can be produced with various intermediate substrates (such as foam, cotton paper, PET, etc.).

[0066] Drying and Curing: The coated adhesive layer is placed in an oven and dried at 60°C for 1-5 minutes to remove solvents, then placed in a 100°C oven for 1-5 minutes to further remove solvents and residual monomers. The coated tape is then cured at 60°C for 24-48 hours to ensure complete curing. This yields a stable, plasticizer-resistant acrylic pressure-sensitive tape.

[0067] The above preparation method is based on mature solution polymerization and physical blending processes, requires no complex equipment modification, has good dispersion of porous particles, stable storage of the adhesive solution, and is easy to industrialize.

[0068] The technical solution of the present invention will be further described in detail below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0069] Table 1 shows the names, abbreviations, and corresponding manufacturers of the main raw materials used in the embodiments and comparative examples of this invention. It should be noted that the raw materials used in Table 1 are for experimental purposes only. Raw materials with similar chemical composition and structure purchased from other suppliers can achieve the same effect and are also within the scope of protection of this invention.

[0070] Table 1. Information on Main Raw Materials

[0071] To better illustrate the implementation method of the present invention, the following examples and comparative examples are provided, with specific formulations, dosages, and preparation steps as follows. In the examples and comparative examples, "parts" refers to parts by weight. Example

[0072] The preparation steps of the pressure-sensitive adhesive in this embodiment are as follows:

[0073] 89 parts BA, 6 parts MA, 5 parts AA, 0.1 parts 2-HEA, 0.01 parts dodecyl mercaptan, and 120 parts ethyl acetate (EAc) solvent were mixed thoroughly in a beaker to obtain a mixed solvent. Half of this mixed solvent was then added to a reaction vessel equipped with a stirrer, nitrogen line, condenser, thermometer, and dropping device. The remaining half was placed in a constant pressure funnel and added dropwise during the reaction. The solution in the reaction vessel was heated to 63±0.3°C, and nitrogen gas was purged at this temperature for 30 minutes. After the nitrogen purging was complete, 0.1 parts of azobisisobutyronitrile (AIBN) initiator were added to begin the reaction. The temperature was controlled at 63±0.3°C for the first 0-2 hours of the reaction. At the 3-hour mark, 0.1 parts of AIBN were added, and the remaining half of the monomer / solvent mixture was added dropwise over 2 hours, with the temperature maintained at 68±1°C throughout the process. After 5 hours of reaction, add the remaining 0.1 parts of AIBN initiator and heat to above 76°C, maintaining this temperature until the reaction ends in 7 hours. Then add 30 parts of ethyl acetate as a diluent and cool the polymer solution to room temperature.

[0074] To approximately 250 parts of the prepared acrylate polymer solution (approximately 100 parts polymer and 150 parts solvent), 10 parts of TP2040, 10 parts of K806, and 0.2 parts of N3300 were added sequentially and stirred. Then, 50 parts of ethyl acetate and 3 parts of MR-7GCP were added and stirred for 3 minutes, followed by sonication for 5 minutes. The two liquids were then mixed at room temperature and stirred again for 5 minutes, at which point the particles were uniformly dispersed, forming a homogeneous mixture.

[0075] The prepared pressure-sensitive adhesive (approximately 38% coating solids content) was evenly coated onto a 50μm PET substrate using an adjustable slit thickness applicator (approximately 200μm), resulting in an adhesive thickness of approximately 50μm. The coated adhesive layer was then placed in an oven at 60°C for 3 minutes to remove solvents, followed by 3 minutes at 105°C to further remove solvents and residual monomers. The coated tape was then cured at 60°C for 48 hours to ensure complete curing.

[0076] The overall steps of this comparative example are the same as those of Example 1, except that in step (2), microspheres MR-7GCP are not added, but 50 parts of ethyl acetate diluent are added. Specifically, step (2) of this comparative example is as follows: 10 parts of TP2040, 10 parts of K806, and 0.2 parts of N3300 are added sequentially to 250 parts of the acrylate polymer solution prepared in step (1) (approximately 100 parts of polymer and 150 parts of solvent), and stirred. At room temperature, 50 parts of ethyl acetate diluent are added to the above liquid, and the mixture is stirred again for 5 minutes to form a mixture. The remaining raw material amounts and steps of this comparative example are the same as those of Example 1. Example

[0077] The overall steps of this embodiment are the same as those of Embodiment 1, except that in step (1), the amount of BA in the polymer solution preparation formula is changed to 86 parts, the amount of AA is reduced to 2 parts, and 6 parts of β-CEA are added. The remaining raw material amounts and steps of this embodiment are the same as those of Embodiment 1.

[0078] The overall steps of this comparative example are the same as those of Example 2, except that in step (1), the amount of EHA added in the polymer solution preparation formula is 60 parts and the amount of BA added is 26 parts. The remaining raw material amounts and steps of this comparative example are the same as those of Example 2.

[0079] The overall steps of this comparative example are the same as those of Example 2, except that in step (2), the contents of resin TP2040 and K806 are reduced to 2 parts and 2 parts, respectively. The remaining raw material amounts and steps of this comparative example are the same as those of Example 2.

[0080] The formulations of Examples 1 to 2 and Comparative Examples 1 to 3 are shown in Table 2.

[0081] Table 2 Formulations of Examples 1 to 2 and Comparative Examples 1 to 3 Example

[0082] The overall steps of this embodiment are the same as those of Embodiment 2, except that in step (1), the composition of EHA and BA in the polymer solution preparation formula is changed to 10 parts and 76 parts respectively. The remaining raw material amounts and steps of this embodiment are the same as those of Embodiment 2.

[0083] The overall steps of this comparative example are the same as those of Example 3, except that the type of microspheres used in the adhesive compounding process is changed in step (2). The porous microspheres MR-7GCP are replaced with non-porous microspheres MR-7GC, both of which have the same particle size (7μm). The remaining raw material amounts and steps of this comparative example are the same as those of Example 3. Example

[0084] The overall steps of this embodiment are the same as those of Embodiment 3, except that in step (1), the ratio of EHA to BA in the polymer solution preparation formula is changed to 20 parts and 66 parts. The remaining raw material amounts and steps of this embodiment are the same as those of Embodiment 3.

[0085] The overall steps of this comparative example are the same as those of Example 4, except that the chain transfer agent dodecyl mercaptan was omitted in step (1). The remaining raw material amounts and steps of this comparative example are the same as those of Example 4. The polymer obtained in Comparative Example 5 has a higher molecular weight. Example

[0086] The overall steps of this embodiment are the same as those of Embodiment 3, except that the amounts of resin and microspheres are different in step (2). The resin ratio was changed to a certain extent, increasing the content of resin K806 with a lower softening point, decreasing the content of resin TO2040, and increasing the content of porous microspheres MR-7GCP.

[0087] The formulations of Examples 3 to 5 and Comparative Examples 4 to 5 are shown in Table 3.

[0088] Table 3 Formulations of Examples 3 to 5 and Comparative Examples 4 to 5

[0089] After the polymer solution preparation stage of Examples 1 to 5 and Comparative Examples 1 to 5 was completed, and before the compounded adhesive was coated and cured, the uncrosslinked polymer solution was used for molecular weight testing. Simultaneously, the acrylic pressure-sensitive tapes of Examples 1 to 5 and Comparative Examples 1 to 5 prepared according to the above method were bonded to a clean 500μm transparent soft PVC substrate, and peel strength tests were conducted at room temperature (180°C), after aging for 160 hours, and after aging for 500 hours to verify their plasticizer resistance.

[0090] The equipment and methods used for relevant performance testing are as follows.

[0091] Molecular weight determination: Molecular weight and molecular weight distribution were determined using a gel permeation chromatography system (Waters, model 2707) with tetrahydrofuran as the mobile phase and a flow rate of 1 mL / min.

[0092] Peel strength test: The test shall be conducted in accordance with the test method in GB / T 2792-2014.

[0093] Peel strength test after aging: After preparing the sample according to the method of GB / T 2792-2014, the sample was placed in a 60℃ oven for 160h and 500h. After taking it out, it was placed in a constant temperature and humidity room for 2h before the peel strength test was performed.

[0094] The test results are shown in Table 4.

[0095] Table 4 Test Results

[0096] The results above show that the preparation process of the polymer solution is generally stable. Except for Comparative Example 4, which does not use a chain transfer agent and has a significantly higher median molecular weight, the weight-average molecular weights of the other samples are all between 400 kg / mol and 600 kg / mol.

[0097] The results of Example 1 and Comparative Example 1 show that a formulation with higher polarity can effectively improve the plasticizer resistance of the tape; the plasticizer resistance was significantly improved after adding porous microspheres MR-7GCP. The peel force test results of the two samples after 160 hours of aging were not significantly different, but the peel force test results after 500 hours of aging showed a significant difference, indicating the long-term effect of porous microspheres on the plasticizer resistance of the tape.

[0098] The results of Example 2 and Comparative Example 2 indicate that in the polymer preparation formulation, excessive nonpolar monomers (EHA) make the final tape more susceptible to plasticizer absorption, resulting in a significant decrease in plasticizer resistance.

[0099] The results of Examples 2 and 3 show that the resin content has a significant effect on the adhesive properties and plasticizer resistance of the tape. When the resin content is low, the resin cannot form an effective insulating zone to prevent plasticizer migration from the soft PVC; simultaneously, the reduction in resin content also significantly reduces the adhesive properties of the tape.

[0100] The results of Examples 3 and 4 show that the addition of any type of microsphere improves the plasticizer resistance of the tape to some extent, but the effect of porous microspheres is more significant. This is because the porous structure of the microspheres facilitates the anchoring of the polymer in the tape and the absorption of plasticizers.

[0101] The results of Examples 4 and 5 indicate that higher polymer molecular weight is detrimental to improving the tape's resistance to accelerators. This is because high molecular weight polymers are less conducive to the dispersion of porous microspheres, leading to a weakening of their plasticizer resistance.

[0102] The results of Examples 1 and 2 show that replacing the classic AA monomer with β-CEA (Example 2), which has the same carboxyl content but better flexibility, can increase the peel strength of the tape without reducing its plasticizer resistance. This is because the tape containing β-CEA has a lower modulus than the tape containing AA, which is beneficial for wetting during bonding.

[0103] A comparison between Example 5 and Example 3 shows that, based on Example 3, the adhesive performance and plasticizer resistance of the tape can be further improved by optimizing the resin ratio and the content of porous microspheres. Compared with Example 3, Example 5 increased the content of porous microspheres; simultaneously, in order to balance the increase in tape modulus caused by the increased porous microspheres, the resin ratio was adjusted in the direction of reducing the modulus, thereby achieving the improvement of adhesive performance and plasticizer resistance.

[0104] The results of Examples 2, 3, Comparative Example 3, and 5 indicate that the resin ratio and content during the adhesive compounding stage have a significant impact on the adhesion of the tape to soft PVC and its resistance to plasticizers. The resin in the tape promotes interfacial adhesion and physically blocks plasticizer migration.

[0105] The results of Examples 2, 3, and 4 show that the ratio of EHA to BA in the polymer formulation has a significant impact on the adhesion performance and plasticizer resistance of the tape on soft PVC. A higher EHA content in the polymer leads to easier absorption and diffusion of plasticizers by the tape. While a higher BA content can somewhat resist the diffusion and migration of plasticizers, it results in a higher modulus of the tape, which impairs wetting during bonding. A suitable ratio of EHA to BA, combined with the blocking, absorption, and anchoring effects of porous microspheres, can significantly improve the tape's resistance to accelerators.

[0106] The test results of the above embodiments and comparative examples are analyzed in Table 5 below.

[0107] Table 5. Analysis of Experimental Results

[0108] As can be seen from the above, the plasticizer-resistant pressure-sensitive tape of the present invention, while introducing porous micron-sized particles, ensures excellent initial tack, peel strength, and flexibility through polymer chain segment design, appropriate chemical crosslinking, and the use of a certain amount of tackifying resin, thus avoiding the problem of increased brittleness caused by simply increasing the crosslinking density. The final product is an acrylic pressure-sensitive tape with excellent plasticizer resistance, exhibiting a peel strength of 20 N / 25mm~23 N / 25mm at room temperature and 19 N / 25mm~21 N / 25mm after aging at 60℃ for 500 hours when bonded to soft PVC samples.

[0109] Finally, it should be emphasized that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A plasticizer-resistant pressure-sensitive adhesive, characterized in that... It is prepared from the following components in parts by weight: 100 parts of acrylate polymer solution on a solid basis 5 to 30 parts of tackifying resin, 1 to 15 parts of porous micron-sized particles Hardener 0.1 to 10 parts; The acrylate polymer solution is obtained by polymerizing soft monomers, hard monomers, and functional monomers in the presence of a solvent, an initiator, and a chain transfer agent. The mass of the soft monomer accounts for 80% to 95% of the total mass of the soft monomers, hard monomers, and functional monomers. The mass of alkyl acrylates with more than 4 alkyl carbon atoms in the soft monomers accounts for no more than 25% of the total mass of the soft monomers, hard monomers, and functional monomers. The mass of the hard monomer accounts for 0% to 15% of the total mass of the soft monomers, hard monomers, and functional monomers. The mass of the functional monomer accounts for more than 0% and less than or equal to 10% of the total mass of the soft monomers, hard monomers, and functional monomers.

2. The plasticizer-resistant pressure-sensitive adhesive according to claim 1, characterized in that: The soft monomer is at least one of n-butyl acrylate and isobutyl acrylate, or the soft monomer is a mixture of at least one of n-butyl acrylate and isobutyl acrylate and at least one of 2-ethylhexyl acrylate and isooctyl acrylate; The hard monomer is at least one of methyl methacrylate, ethyl methacrylate, styrene, vinyl acetate, and vinyl acetate; The functional monomer is at least one of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, and β-carboxyethyl acrylate.

3. The plasticizer-resistant pressure-sensitive adhesive according to claim 2, characterized in that: The soft monomer is a mixture of n-butyl acrylate and isooctyl acrylate, wherein the mass of isooctyl acrylate accounts for more than 0% and less than or equal to 25% of the total mass of n-butyl acrylate and isooctyl acrylate; The functional monomer contains β-carboxyethyl acrylate, and the mass of β-carboxyethyl acrylate accounts for more than 0% and less than or equal to 75% of the total mass of the functional monomer.

4. A plasticizer-resistant pressure-sensitive adhesive according to any one of claims 1 to 3, characterized in that: The acrylate polymer solution is obtained by solution polymerization of soft monomers, hard monomers and functional monomers in an organic solvent. The organic solvent accounts for 30% to 70% of the mass of the acrylate polymer solution. The organic solvent is at least one of ethyl acetate, toluene and acetone. The mass ratio of soft monomers, hard monomers and functional monomers is (86~89):6:(5~8); The initiator has a mass of 0.1% to 2% of the total mass of the soft monomer, hard monomer and functional monomer, and the initiator is at least one of azobisisobutyronitrile, azobisisoheptanenitrile and benzoyl peroxide; The chain transfer agent is 0.01% to 1% of the total mass of the soft monomer, hard monomer and functional monomer, and the chain transfer agent is n-dodecyl mercaptan; The weight-average molecular weight of the acrylate copolymers obtained by polymerizing soft monomers, hard monomers and functional monomers is 400 kg / mol to 700 kg / mol.

5. A plasticizer-resistant pressure-sensitive adhesive according to any one of claims 1 to 3, characterized in that: The particle size of the porous micron-sized particles ranges from 1 μm to 50 μm. The tackifying resin is at least one of terpene phenolic tackifying resins and rosin-based tackifying resins; The curing agent is at least one of the following: polyisocyanate toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, hydrogenated xylene diisocyanate, HDI trimer, metal chelate, epoxy compound, and aziridine. Plasticizer-resistant pressure-sensitive adhesives also contain a diluent when compounded, with the diluent's mass being 0% to 50% of the acrylate polymer solution.

6. A method for preparing a plasticizer-resistant pressure-sensitive adhesive according to any one of claims 1 to 5, characterized in that... Includes the following steps: Add tackifying resin, porous micron particles and a portion of diluent to an acrylate polymer solution, and stir to disperse and mix at room temperature or below 50°C to form a homogeneous mixture; A curing agent is added at room temperature, and after stirring, coating, drying, curing, and die-cutting, pressure-sensitive adhesive tape is obtained.

7. The method for preparing a plasticizer-resistant pressure-sensitive adhesive according to claim 6, characterized in that... The preparation method of the acrylate polymer solution includes the following steps: The soft monomer, hard monomer, functional monomer, and organic solvent are mixed evenly to obtain a mixed solution; a portion of the mixed solution is added to a reaction vessel equipped with a stirrer, nitrogen line, condenser, thermometer, and dropping device; the remaining portion of the mixed solution is loaded into the dropping device. The mixed solution in the reactor is heated to a specific temperature of 61 ℃ to 66 ℃, nitrogen gas is continuously introduced and stirred, the first part of the initiator is added, and the temperature is controlled at 61 ℃ to 66 ℃ during the first 0 to 2 hours of reaction; during the second 3 to 5 hours of reaction, the mixed solution in the dropping device is gradually added dropwise, and the second part of the initiator is added, and the temperature is controlled at 66 ℃ to 70 ℃; after 6 hours of reaction, the remaining initiator is added and the temperature is raised to above 76 ℃, and this temperature is maintained until the 8th hour, at which point the solvent for dilution is added, and the reaction ends. The reaction system was cooled to below 40°C to obtain an acrylate polymer solution.

8. An adhesive tape, comprising a substrate and an adhesive layer disposed on the substrate, characterized in that... The adhesive layer is made of a plasticizer-resistant pressure-sensitive adhesive as described in any one of claims 1 to 5 or a pressure-sensitive adhesive prepared by the preparation method described in claim 6 or 7.

9. The method for preparing an adhesive tape according to claim 8, characterized in that... Includes the following steps: The pressure-sensitive adhesive is uniformly coated onto one surface of a substrate by means of doctor blade coating, roller coating, or comma coating. The substrate is a PET film, PI film, BOPP film, or release film. The coated adhesive layer is placed in an oven and dried at 50℃~60℃ for 1 minute to 5 minutes to remove the solvent. Then it is placed in an oven at 80℃~100℃ for 1 minute to 5 minutes to further remove the solvent and residual monomers. Subsequently, the coated tape is cured at 50℃~60℃ for 24 hours to 48 hours to allow the curing agent to react completely, and the tape is obtained.

10. An adhesive composite material, comprising PVC and an adhesive layer disposed on the surface of the PVC, characterized in that... The adhesive layer is made of a plasticizer-resistant pressure-sensitive adhesive as described in any one of claims 1 to 5, or a pressure-sensitive adhesive prepared by the preparation method described in claim 6 or 7, or a tape as described in claim 8, or a tape prepared by the preparation method described in claim 9.

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