Thermal visbreaking pressure-sensitive adhesive, integrated foam double-sided adhesive tape and preparation method of integrated foam double-sided adhesive tape

Abstract

The invention relates to a thermal visbreaking pressure-sensitive adhesive, an integrated foam double-sided adhesive tape and a preparation method thereof, the thermal visbreaking pressure-sensitive adhesive comprises the following raw materials: an acrylate polymer solution, a rubber elastomer, tackifying resin, a foaming agent and a curing agent; the acrylate polymer solution is prepared from the following raw materials in parts by mass: 10 to 30 parts of cyclopentadienyl acrylate monomers, 10 to 20 parts of 2-ethylhexyl acrylate, 20 to 70 parts of ethyl acrylate, 4 to 18 parts of methyl methacrylate, 2 to 15 parts of 2-hydroxyethyl acrylate, 0.1 to 1 part of an initiator and 150 to 350 parts of a solvent; the thermal viscosity-reducing pressure-sensitive adhesive has the characteristics of high viscosity at room temperature and greatly reduced stripping force at high temperature, so that an adhered base material can be reused, and the cost is saved. The integrated foam double-sided adhesive tape is prepared by coating the release film with the thermal viscosity-reducing pressure-sensitive adhesive and then drying and foaming, and a closed-cell structure is formed by foaming, so that the adhesive layer has good rebound resilience and impact resistance.

Description

Technical Field

[0001] The invention belongs to the field of adhesives, and in particular relates to a heat-reducing pressure-sensitive adhesive, an integrated foam double-sided adhesive tape and a preparation method thereof. Background Art

[0002] Foam tape is widely used due to its excellent cushioning and protective properties. In the 3C industry (computer, communication and consumer electronics industry), it is not only used for product packaging, but also for fixing and protecting internal parts, as well as positioning and marking during the manufacturing process.

[0003] The 3C industry has a fast product replacement speed, and manufacturers are paying more and more attention to recyclability and reusability. In addition, as 3C products develop towards lighter, thinner and more sophisticated directions, the requirements for fixing and protecting internal components are also getting higher and higher, and foam tapes also need to provide effective solutions. The application of heat-reducing foam tape in the 3C industry is gradually increasing, mainly due to its unique hot-melt properties and environmental advantages. This tape can quickly release its adhesive force at high temperatures, making it easier to disassemble and repair products, which is particularly important for after-sales service and recycling of 3C products.

[0004] In the process of realizing the present invention, the inventors found that there are at least the following problems in the prior art. Patent CN118185519A discloses a method for preparing a heat-reducing pressure-sensitive adhesive tape, and the heat-reducing foam tape is prepared by using foamed cotton as the core material and laminating the heat-reducing adhesive layer. This process has the risk of separation of the adhesive layer and the foam core material; Patent CN 115785844A discloses a heat-reducing protective film tape, which uses sodium bicarbonate to decompose and release carbon dioxide and water when heated. The released carbon dioxide gas expands the colloid, and the generated water is absorbed by bentonite to expand the colloid again, thereby reducing the contact area between the colloid and the laminating material, reducing the viscosity, and achieving a peeling effect. The reaction is irreversible, and the tape can only be used once. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a heat-reducing pressure-sensitive adhesive, an integrated foam double-sided tape and a preparation method thereof:

[0006] The invention provides a heat-reducing viscosity-reducing pressure-sensitive adhesive, which comprises the following raw materials, by weight: 200 to 450 parts of an acrylic polymer solution, 40 to 60 parts of a rubber elastic body, 15 to 35 parts of a tackifying resin, 0.4 to 1.6 parts of a foaming agent, 0.02 to 0.2 parts of a curing agent, and 50 to 150 parts of a solvent;

[0007] The acrylate polymer solution comprises the following raw materials in parts by weight: 10 to 30 parts of cyclopentadienyl acrylate monomers, 10 to 20 parts of isooctyl acrylate, 20 to 70 parts of ethyl acrylate, 4 to 18 parts of methyl methacrylate, 2 to 15 parts of 2-hydroxyethyl acrylate, 0.1 to 1 part of initiator, and 150 to 350 parts of solvent;

[0008] The cyclopentadienyl acrylate monomer includes one or more of cyclopentadienyl ethyl acrylate, ethylene glycol dicyclopentenyl ether acrylate, dicyclopentadiene acrylate, dicyclopentenyl ethoxy acrylate, isobornyl acrylate, and cyclotrimethylolpropane formal acrylate, preferably, cyclopentadienyl ethyl acrylate and / or dicyclopentadiene acrylate, more preferably, cyclopentadienyl ethyl acrylate;

[0009] The initiator is one or more of cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, azobisisobutyronitrile, azobisisoheptanenitrile, and dimethyl azobisisobutyrate, preferably tert-butyl hydroperoxide and / or azobisisobutyronitrile, more preferably azobisisobutyronitrile;

[0010] The solvent in the heat-reducing pressure-sensitive adhesive and the solvent in the acrylate polymer solution are the same solvent, which is one or more of benzene, alcohols, esters, and ketones, preferably one or more of ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, acetone, butanone, cyclohexanone, and butanol, more preferably ethyl acetate and / or butyl acetate;

[0011] The mass ratio of the cyclopentadienyl acrylate monomer, isooctyl acrylate, ethyl acrylate, methyl methacrylate, and 2-hydroxyethyl acrylate is preferably (15-25): (15-20): (40-60): (5-15): (5-10);

[0012] The rubber elastic body is one or more of SBS, SIS, isoprene rubber, styrene-butadiene rubber, natural rubber and chloroprene rubber, preferably SBS and SIS, more preferably, the dry weight ratio of SBS to SIS is one of 3:7, 4:6, 5:5 and 6:4;

[0013] The tackifying resin is one or more of rosin resin, petroleum resin, coumarone resin, phenolic resin, terpene resin, and epoxy resin, preferably terpene resin;

[0014] The diameter of the foaming agent is 5-9 μm before foaming and 16-30 μm after foaming; preferably, it is Nouryon PVC microsphere expansion agent; more preferably, it is 920DU20 model;

[0015] The curing agent is a room temperature curing agent and a heating curing agent. The room temperature curing agent is one or more of polyisocyanates, epoxies, aliphatic polyamines, alicyclic polyamines, polyamides and modified aromatic amines. The heating curing agent is one or more of aromatic polyamines, acid anhydrides, resol phenolic resins, amino resins, metal salts and dicyandiamides. Preferably, the curing agent is an epoxy curing agent or a metal salt curing agent. More preferably, the mass ratio of the epoxy curing agent to the metal salt curing agent is 3:7.

[0016] The present invention provides a method for preparing a heat-reducing pressure-sensitive adhesive as described in any of the above schemes, comprising three steps:

[0017] Step 1: Under a nitrogen environment, cyclopentadienyl acrylate monomer, ethyl acrylate and one third of solvent are added into a four-necked flask and heated to 60-80° C., and then half of the initiator is added dropwise, and the reaction is carried out for 60-120 minutes;

[0018] Step 2: Mix isooctyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate, the remaining half of the initiator, and one third of the solvent, and then add them dropwise into a four-necked flask. The reaction temperature is 70-90° C. and the reaction time is 4-6 hours. After the reaction is completed, cool to 50° C. and keep warm for 30 minutes to obtain an acrylate polymer solution.

[0019] Step 3: Dissolve the rubber elastomer and tackifying resin with the remaining 90% solvent and add them into a four-necked flask, increase the stirring speed to 1000-1800 rpm, and mix for 20 minutes; then reduce the stirring speed to 500-600 rpm, add the foaming agent and curing agent pre-dispersed with the remaining 10% solvent, and stir for 10 minutes to obtain the heat-reducing pressure-sensitive adhesive.

[0020] The addition ratio of the solvent in step 1, step 2 and step 3 of the present invention is calculated based on the sum of the solvents required in each step of preparing the heat-reducing viscosity-reducing pressure-sensitive adhesive.

[0021] The present invention provides an integrated foam double-sided tape, which comprises a first release film layer, a heat-reducing foam layer and a second release film layer stacked in sequence; the heat-reducing foam layer is prepared by coating the heat-reducing pressure-sensitive adhesive, drying for primary crosslinking, high-temperature foaming, and aging for secondary crosslinking.

[0022] Preferably, the release force of the first release film is 5-10 gf / in, and the release force of the second release film is 10-15 gf / in; the thickness of the thermal viscosity-reducing foam layer is 100-200 μm;

[0023] The present invention provides a preparation method of an integrated foam double-sided tape, comprising: coating the heat-reducing viscosity pressure-sensitive adhesive on a first release film, drying and foaming at high temperature to form a heat-reducing viscosity foam layer, then laminating the heat-reducing viscosity foam layer on a second release film, rolling it up and aging it in a drying room to obtain an integrated foam double-sided tape.

[0024] Preferably, the drying condition is 100-120° C. for 3-5 minutes, the high temperature foaming condition is 140-160° C. for 3-5 minutes, and the aging condition is 38-60° C. for 2-3 days; and the winding method is winding with the second release film facing inward.

[0025] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0026] 1. The heat-reducing pressure-sensitive adhesive provided by the present invention has the characteristics of high viscosity at room temperature and greatly reduced peeling force at high temperature, so that the foam tape can be peeled off for rework, and the adhered substrate can be reused to save costs; the cyclopentadienyl acrylate monomer in the heat-reducing pressure-sensitive adhesive dimerizes into dicyclopentadiene at room temperature, polymerizes with acrylate monomers to form acrylate long-chain polymers, and is cross-linked by a curing agent to form a three-dimensional network structure, and has high viscosity at room temperature; at a high temperature of 170°C, dicyclopentadiene undergoes a dedimerization reaction to generate cyclopentadiene, and the long polymer chain breaks, resulting in partial destruction of the three-dimensional network structure, increased fluidity, narrowed molecular weight distribution, and reduced peeling strength of the pressure-sensitive adhesive, thereby achieving the effect of heat-reducing pressure-sensitive adhesive.

[0027] 2. In the preparation process of the heat-reducing viscosity-sensitive adhesive, the rubber elastomer mixture is uniformly dispersed in the acrylic polymer solution in the form of small particles through high-speed stirring; after the heat-reducing viscosity-sensitive adhesive is prepared, it should be coated within 5 hours and then dried at 100-120°C. During this period, the metal salt curing agent has a fast reaction rate, so that the coated heat-reducing viscosity-sensitive adhesive layer can complete the first cross-linking and curing after drying, and the small particles of rubber elastomer are uniformly dispersed in the heat-reducing viscosity-sensitive adhesive. The form is fixed; at the same time, the introduction of rubber elastomer in the heat-reducing viscosity-sensitive adhesive makes the acrylic foam adhesive present the characteristics of high modulus.

[0028] 3. By subjecting the heat-reducing pressure-sensitive adhesive layer coated on the first release film to high-temperature foaming, the foaming agent is foamed from 5 to 9 μm to 16 to 30 μm, thereby obtaining a closed-cell acrylic foam adhesive with good resilience and impact resistance. Thanks to the fact that the small rubber elastic particles are evenly dispersed in the heat-reducing pressure-sensitive adhesive during drying, after high-temperature foaming, the small rubber elastic particles can be stable in the foam tape for a long time without precipitation, thereby maintaining the good resilience and impact resistance of the foam tape.

[0029] 4. The epoxy curing agent in the heat-reducing pressure-sensitive adhesive is a curing agent with a slow reaction rate. Its cross-linking curing reaction continues until the aging stage is completed. During this process, the cross-linked network structure of the polymer is continuously strengthened, which improves the cohesive force of the adhesive layer, thereby greatly improving the bonding strength of the tape, and achieving the foam tape with high viscosity and good strength and impact resistance.

[0030] 5. The integrated foam double-sided adhesive is made by coating a heat-reducing pressure-sensitive adhesive on a release film and then drying and foaming it. The integrated process ensures the high viscosity of the tape. At the same time, due to the closed-cell structure formed by foaming, the adhesive layer has good resilience and excellent impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a side cross-sectional electron microscope image of the integrated foam double-sided tape obtained in Example 1. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the embodiments and comparative examples of the present invention, the raw materials used are shown in the following table:

[0034]

[0035] Embodiment 1:

[0036] The formula of the reversible heat-reducing viscosity-reducing pressure-sensitive adhesive of this embodiment is: 20g of cyclopentadienyl ethyl acrylate, 17g of isooctyl acrylate, 50g of ethyl acrylate, 7g of methyl methacrylate, 6g of 2-hydroxyethyl acrylate, 0.6g of initiator AIBN, 330g of butyl acetate, 30g of rubber elastomer SIS, 20g of SBS, 25g of resin TR B115, 201g of foaming agent 920DU, 0.03g of curing agent EC303, and 0.07g of curing agent aluminum acetylacetonate.

[0037] The method for manufacturing the reversible heat-reducing double-sided adhesive tape of this embodiment comprises the following steps:

[0038] (1) 20 g of ethyl cyclopentadienylacrylate, 50 g of ethyl acrylate and 100 g of butyl acetate were added to a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen inlet tube and a dropping funnel, and heated to 70° C. The stirring speed was set to 300 r / min, and 0.3 g of initiator AIBN (dissolved in 10 g of butyl acetate) was added to initiate the reaction, and the reaction was carried out at 68-72° C. for 90 minutes; 17 g of isooctyl acrylate, 7 g of methyl methacrylate, 6 g of 2-hydroxyethyl acrylate, 110 g of butyl acetate and 0.3 g of initiator AIBN were mixed uniformly and added to the dropping funnel, and the mixture was added dropwise to the reaction system at a uniform speed within 90 minutes, maintaining the temperature at 85-88° C.; after the dropwise addition was completed, the mixture was kept warm for 300 minutes, cooled to below 50° C., and kept warm for 30 minutes to obtain an acrylate polymer solution for standby use.

[0039] (2) 30 g SIS, 20 g SBS and 25 g resin TR B115 were dissolved in 99 g butyl acetate and then slowly added to the acrylate polymer solution obtained in step (1), the stirring speed was increased to 1500 rpm, and the mixture was stirred for 20 minutes; then the stirring speed was reduced to 580 rpm, 1 g foaming agent 920DU20, 0.03 g curing agent EC303 and 0.07 g curing agent aluminum acetylacetonate (the foaming agent and curing agent were pre-dispersed with 11 g butyl acetate in advance) were added, and the mixture was stirred for 10 minutes. After stirring evenly, a heat-reduced viscosity-reducing pressure-sensitive adhesive that can be coated on a machine was obtained.

[0040] (3) The pressure-sensitive adhesive obtained in step (2) is coated on the first release film, and baked at 110° C. for 3 minutes to form a pressure-sensitive adhesive layer (the thickness of the dry adhesive film is controlled to be 160±10 μm), and then baked at 155° C. for 3 minutes to form a heat-resistant foam adhesive layer through high-temperature foaming, and then the heat-resistant foam adhesive layer is laminated on the second release film, and after winding, it is aged in a drying oven at 48° C. for 2 days to obtain an integrated foam double-sided adhesive tape.

[0041] Embodiment 2:

[0042] The formula of the reversible heat-reducing viscosity-reducing pressure-sensitive adhesive of this embodiment is: 15g of cyclopentadienyl ethyl acrylate, 15g of isooctyl acrylate, 40g of ethyl acrylate, 5g of methyl methacrylate, 5g of 2-hydroxyethyl acrylate, 0.3g of initiator AIBN, 270g of butyl acetate, 25g of rubber elastomer SIS, 15g of SBS, 15g of resin TR B115, 200.4g of foaming agent 920DU, 0.024g of curing agent EC303, and 0.056g of curing agent aluminum acetylacetonate.

[0043] The method for manufacturing the reversible heat-reducing double-sided adhesive tape of this embodiment comprises the following steps:

[0044] (1) 15 g of ethyl cyclopentadienylacrylate, 40 g of ethyl acrylate and 80 g of butyl acetate were added to a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen inlet tube and a dropping funnel, and heated to 70° C. The stirring speed was set to 300 r / min, and 0.15 g of initiator AIBN (dissolved in 10 g of butyl acetate) was added to initiate the reaction, and the reaction was carried out at 68-72° C. for 90 minutes; 15 g of isooctyl acrylate, 5 g of methyl methacrylate, 5 g of 2-hydroxyethyl acrylate, 90 g of butyl acetate and 0.15 g of initiator AIBN were mixed uniformly and added to the dropping funnel, and the mixture was added dropwise to the reaction system at a uniform speed within 90 minutes, and the temperature was maintained at 85-88° C.; after the addition was completed, the mixture was kept warm for 300 minutes, cooled to below 50° C., and kept warm for 30 minutes to obtain an acrylate polymer solution for standby use.

[0045] (2) 25 g SIS, 15 g SBS and 15 g resin TR B115 were dissolved in 81 g butyl acetate and then slowly added to the acrylate polymer solution obtained in step (1), the stirring speed was increased to 1500 rpm, and the mixture was stirred for 20 minutes; then the stirring speed was reduced to 580 rpm, 0.4 g foaming agent 920DU20, 0.024 g curing agent EC303 and 0.056 g curing agent aluminum acetylacetonate (the foaming agent and curing agent were pre-dispersed with 9 g butyl acetate in advance) were added, and the mixture was stirred for 10 minutes. After the mixture was stirred evenly, a heat-reduced viscosity-reducing pressure-sensitive adhesive that can be coated on a machine was obtained.

[0046] (3) The pressure-sensitive adhesive obtained in step (2) is coated on the first release film, and baked at 110° C. for 3 minutes to form a pressure-sensitive adhesive layer (the thickness of the dry adhesive film is controlled to be 160±10 μm), and then baked at 155° C. for 3 minutes to form a heat-resistant foam adhesive layer through high-temperature foaming, and then the heat-resistant foam adhesive layer is laminated on the second release film, and after winding, it is aged in a drying oven at 48° C. for 2 days to obtain an integrated foam double-sided adhesive tape.

[0047] Embodiment 3:

[0048] The formula of the reversible heat-reducing viscosity-reducing pressure-sensitive adhesive of this embodiment is: 25g of cyclopentadienyl ethyl acrylate, 20g of isooctyl acrylate, 60g of ethyl acrylate, 15g of methyl methacrylate, 10g of 2-hydroxyethyl acrylate, 1g of initiator AIBN, 420g of butyl acetate, 35g of rubber elastomer SIS, 25g of SBS, 35g of resin TR B115, 1.6g of foaming agent 920DU20, 0.039g of curing agent EC303, and 0.091g of curing agent aluminum acetylacetonate.

[0049] The method for manufacturing the reversible heat-reducing double-sided adhesive tape of this embodiment comprises the following steps:

[0050] (1) 25 g of cyclopentadienyl ethyl acrylate, 60 g of ethyl acrylate, and 130 g of butyl acetate were added to a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen inlet tube, and a dropping funnel, and heated to 70° C. The stirring speed was set to 300 r / min, and 0.5 g of initiator AIBN (dissolved in 10 g of butyl acetate) was added to initiate the reaction, and the reaction was carried out at 68-72° C. for 90 minutes; 20 g of isooctyl acrylate, 15 g of methyl methacrylate, 10 g of 2-hydroxyethyl acrylate, 140 g of butyl acetate, and 0.5 g of initiator AIBN were mixed uniformly and added to the dropping funnel, and the mixture was added dropwise to the reaction system at a uniform speed within 90 minutes, maintaining the temperature at 85-88° C.; after the addition was completed, the mixture was kept warm for 300 minutes, cooled to below 50° C., and kept warm for 30 minutes to obtain an acrylate polymer solution for standby use.

[0051] (2) 35 g SIS, 25 g SBS and 35 g resin TR B115 were dissolved in 126 g butyl acetate and then slowly added to the acrylate polymer solution obtained in step (1), the stirring speed was increased to 1500 rpm, and the mixture was stirred for 20 minutes; then the stirring speed was reduced to 580 rpm, 1.6 g foaming agent 920DU20, 0.039 g curing agent EC303 and 0.091 g curing agent aluminum acetylacetonate (the foaming agent and curing agent were pre-dispersed with 14 g butyl acetate in advance) were added, and the mixture was stirred for 10 minutes. After stirring evenly, a heat-reduced viscosity-reducing pressure-sensitive adhesive that can be coated on a machine was obtained.

[0052] (3) The pressure-sensitive adhesive obtained in step (2) is coated on the first release film, and baked at 110° C. for 3 minutes to form a pressure-sensitive adhesive layer (the thickness of the dry adhesive film is controlled to be 160±10 μm), and then baked at 155° C. for 3 minutes to form a heat-resistant foam adhesive layer through high-temperature foaming, and then the heat-resistant foam adhesive layer is laminated on the second release film, and after winding, it is aged in a drying oven at 48° C. for 2 days to obtain an integrated foam double-sided adhesive tape.

[0053] Comparative Example 1: Compared with Example 1, except that cyclopentadienyl acrylate monomer is not added in the formula, the rest are the same;

[0054] Comparative Example 2: Compared with Example 1, except that the rubber elastic body is not added in the formula, the rest are the same;

[0055] Comparative Example 3: Compared with Example 1, except that aluminum acetylacetonate curing agent is not added in the formula, the rest are the same;

[0056] Comparative Example 4: Compared with Example 1, except that no epoxy curing agent is added to the formula, the rest are the same;

[0057] Comparative Example 5: Compared with Example 1, except that the amount of foaming agent in the formula is too small, the rest is the same;

[0058] Comparative Example 6: Compared with Example 1, except that the amount of foaming agent in the formula is too much, the rest is the same.

[0059] Test: The integrated foam double-sided tapes prepared in Examples 1 to 3 and Comparative Examples 1 to 6 were subjected to performance tests as follows.

[0060] 1. Storage modulus G'

[0061] Test instrument: Rotational rheometer

[0062] First, stack 6 layers of foam tape together, then make a disc sample with a diameter of 8mm, put it into the rheometer for testing, set the temperature scan to -50℃~150℃, read the storage modulus G' data of the material at 23℃ and record it. Storage modulus (elastic modulus) refers to the amount of energy stored in the material due to elastic (reversible) deformation when it is deformed, reflecting the elasticity of the material.

[0063] 2. Peel force

[0064] Testing equipment: tensile machine

[0065] Test method:

[0066] Room temperature peeling force: Remove the second release film of the foam tape, transfer 50μm PET, and cut into strips of 300mm long and 25.4mm wide. Next, apply these strips to the pre-cleaned SUS steel plate and roll back and forth twice with a 2KG roller. Then store the test sample in a standard climate (air, 23℃, 50% relative humidity) for 20 minutes, and the prepared strips are tested with a tensile machine.

[0067] High temperature peeling force: The prepared room temperature specimens were baked at 170°C for 3 minutes and then immediately tested using a tensile testing machine.

[0068] 3. Impact resistance

[0069] Testing equipment: Drop weight impact testing machine

[0070] Test method: The film is punched into a 20mm*20mm square sample with a mold, attached to a SUS fixture and kept at a pressure of 10.4Kg for 60 seconds at 70℃, and then placed at room temperature for 48 hours before testing. After multiple tests, the energy J required for the sample to be destroyed is obtained.

[0071] The test results are shown in the table below:

[0072] Storage modulus / MPa Room temperature peeling force / gf Peel force after heat reduction / gf Impact resistance / J Example 1 1.12 3520 1096 1.03 Example 2 0.93 3245 1107 0.90 Example 3 1.04 3172 1178 0.98 Comparative Example 1 0.82 3016 2579 0.84 Comparative Example 2 0.36 2850 1276 0.40 Comparative Example 3 0.52 2684 1015 0.48 Comparative Example 4 0.61 2251 986 0.55 Comparative Example 5 0.71 4102 1565 0.42 Comparative Example 6 1.20 2413 914 0.91

[0073] Conclusion: From the data in the table, it can be seen that cyclopentadienyl acrylate monomer was not used in Comparative Example 1, so the film did not have a good thermal viscosity reduction effect. In Comparative Example 2, no rubber elastomer was added, resulting in poor storage modulus and impact resistance. In Comparative Example 3, aluminum acetylacetonate was not added, so the impact resistance of the film after curing was poor. In Comparative Example 4, no epoxy curing agent was used, so the film could not undergo a post-curing reaction, and the cross-linking degree of the film was insufficient, which affected its bonding performance. Although it had a certain thermal viscosity reduction, the bonding strength at room temperature was low. In Comparative Example 5, the amount of foaming agent added was small, the cavity density in the film was low, and although the bonding strength was high, the impact resistance was poor. In Comparative Example 6, the amount of foaming agent added was large, the contact area between the film surface and the adhered object became smaller, the wettability was poor, and although the impact resistance was high, the bonding strength was poor.

[0074] Examples 1 to 3 prepared according to the technical solution provided by the present invention have good thermal viscosity reduction, excellent bonding performance and impact resistance.

[0075] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A heat-reducing pressure-sensitive adhesive, characterized in that: The heat-reducing pressure-sensitive adhesive comprises the following raw materials in parts by weight: 200-450 parts of acrylic polymer solution, 40-60 parts of rubber elastic body, 15-35 parts of tackifying resin, 0.4-1.6 parts of foaming agent, 0.02-0.2 parts of curing agent and 50-150 parts of solvent.

2. The heat-reducing pressure-sensitive adhesive according to claim 1, characterized in that: The acrylic polymer solution comprises the following raw materials in parts by weight: 10 to 30 parts of cyclopentadienyl acrylate monomers, 10 to 20 parts of isooctyl acrylate, 20 to 70 parts of ethyl acrylate, 4 to 18 parts of methyl methacrylate, 2 to 15 parts of 2-hydroxyethyl acrylate, 0.1 to 1 part of initiator, and 150 to 350 parts of solvent.

3. The heat-reducing pressure-sensitive adhesive according to claim 2, characterized in that: The cyclopentadienyl acrylate monomers include one or more of cyclopentadienyl ethyl acrylate, ethylene glycol dicyclopentenyl ether acrylate, dicyclopentadiene acrylate, dicyclopentenyl ethoxy acrylate, isobornyl acrylate, and cyclotrimethylolpropane formal acrylate; preferably, cyclopentadienyl ethyl acrylate and / or dicyclopentadiene acrylate.

4. The heat-reducing pressure-sensitive adhesive according to claim 2, characterized in that: The initiator is one or more of cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, azobisisobutyronitrile, azobisisoheptanenitrile, and dimethyl azobisisobutyrate; preferably, it is tert-butyl hydroperoxide and / or azobisisobutyronitrile.

5. A heat-reducing pressure-sensitive adhesive according to claim 1 or 2, characterized in that: The solvent in the heat-reducing pressure-sensitive adhesive and the solvent in the acrylate polymer solution are the same solvent, which is one or more of benzene, alcohols, esters, and ketones; preferably, one or more of ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, acetone, butanone, cyclohexanone, and butanol; more preferably, ethyl acetate and / or butyl acetate.

6. The heat-reducing pressure-sensitive adhesive according to claim 2, characterized in that: The mass ratio of the cyclopentadienyl acrylate monomer, isooctyl acrylate, ethyl acrylate, methyl methacrylate and 2-hydroxyethyl acrylate is preferably (15-25): (15-20): (40-60): (5-15): (5-10).

7. The heat-reducing pressure-sensitive adhesive according to claim 1, characterized in that: The rubber elastic body is one or more of SBS, SIS, isoprene rubber, styrene-butadiene rubber, natural rubber and chloroprene rubber, preferably SBS and / or SIS; The tackifying resin is one or more of rosin resin, petroleum resin, coumarone resin, phenolic resin, terpene resin, and epoxy resin; preferably, terpene resin; The diameter of the foaming agent is 5-9 μm before foaming and 16-30 μm after foaming; preferably, it is Nouryon PVC microsphere expansion agent; more preferably, it is 920DU20 model; The curing agent is a room temperature curing agent and a heating curing agent. The room temperature curing agent is one or more of polyisocyanates, epoxies, aliphatic polyamines, alicyclic polyamines, polyamides and modified aromatic amines. The heating curing agent is one or more of aromatic polyamines, acid anhydrides, resol phenolic resins, amino resins, metal salts and dicyandiamides. Preferably, the curing agent is an epoxy curing agent or a metal salt curing agent. More preferably, the mass ratio of the epoxy curing agent to the metal salt curing agent is 3:

7.

8. A method for preparing a heat-reducing pressure-sensitive adhesive according to any one of claims 1 to 7, characterized in that: Step 1: Under a nitrogen environment, cyclopentadienyl acrylate monomer, ethyl acrylate and one third of solvent are added into a four-necked flask and heated to 60-80° C., and then half of the initiator is added dropwise, and the reaction is carried out for 60-120 minutes; Step 2: Mix isooctyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate, the remaining half of the initiator, and one third of the solvent, and then add them dropwise into a four-necked flask. The reaction temperature is 70-90° C. and the reaction time is 4-6 hours. After the reaction is completed, cool to 50° C. and keep warm for 30 minutes to obtain an acrylate polymer solution. Step 3: dissolving the rubber elastomer and tackifying resin with the remaining 90% solvent and adding them to the acrylate polymer solution, increasing the stirring speed to 1000-1800 rpm, and mixing for 20 minutes; then reducing the stirring speed to 500-600 rpm, adding the foaming agent and curing agent pre-dispersed with the remaining 10% solvent, and stirring for 10 minutes to obtain the heat-reducing viscosity-reducing pressure-sensitive adhesive.

9. Integrated foam double-sided tape, characterized in that: The integrated foam double-sided tape comprises a stacked first release film layer, a heat-reducing viscosity foam layer and a second release film layer in sequence; the heat-reducing viscosity foam layer is made of the heat-reducing viscosity pressure-sensitive adhesive described in any one of claims 1 to 7 through coating, drying for primary cross-linking, high-temperature foaming, and aging for secondary cross-linking.

10. The integrated foam double-sided tape according to claim 9, characterized in that: The release force of the first release film is 5-10 gf / in, and the release force of the second release film is 10-15 gf / in; the thickness of the thermal viscosity-reducing foam layer is 100-200 μm.

11. The method for preparing the integrated foam double-sided tape according to claim 9 or 10, characterized in that: The method comprises the following steps: coating the heat-reducing viscosity pressure-sensitive adhesive on a first release film, drying and foaming at high temperature to form a heat-reducing viscosity foam layer, laminating the heat-reducing viscosity foam layer on a second release film, rolling it up and curing it in a drying room to obtain an integrated foam double-sided tape.

12. The method for preparing the integrated foam double-sided tape according to claim 11, characterized in that: The drying condition is 100-120° C. for 3-5 minutes, the high-temperature foaming condition is 140-160° C. for 3-5 minutes, and the aging condition is 38-60° C. for 2-3 days.

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