A heat-reducing pressure-sensitive adhesive, integrated foam double-sided tape and preparation method thereof

Abstract

The present invention relates to a heat-reducing pressure-sensitive adhesive, an integrated foam double-sided tape and a preparation method thereof. The heat-reducing pressure-sensitive adhesive comprises the following raw materials: an acrylate polymer solution, a rubber elastomer, a tackifying resin, a foaming agent and a curing agent; the acrylate polymer solution comprises the following raw materials in parts by mass: 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; the heat-reducing pressure-sensitive adhesive has the characteristics of high viscosity at room temperature and a significant decrease in peeling force at high temperature, thereby allowing the adhered substrate to be reused to save costs. The integrated foam double-sided tape is prepared by drying and foaming the heat-reducing pressure-sensitive adhesive after coating the release film. Since the foaming forms a closed-cell structure, the adhesive layer has good resilience and impact resistance.

Description

Technical Field

[0001] The present 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, communications and consumer electronics), 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 experiences rapid product upgrades, leading manufacturers to place increasing emphasis on recyclability and reusability. Furthermore, as 3C products evolve towards thinner, lighter, and more sophisticated designs, the requirements for securing and protecting internal components are becoming increasingly stringent, necessitating the use of foam tapes as effective solutions. Thermally viscous foam tape is seeing increasing adoption in the 3C industry, primarily due to its unique hot-melt properties and environmental advantages. This tape quickly releases its adhesive strength at high temperatures, facilitating product disassembly and repair, a crucial factor in the after-sales service and recycling of 3C products.

[0004] During the implementation of the present invention, the inventors discovered that the prior art has at least the following problems: Patent CN118185519A discloses a method for preparing a heat-reducing pressure-sensitive adhesive tape. This heat-reducing foam tape achieves heat-reduction by using expanded foam as a core material and laminating a heat-reducing adhesive layer. This process carries the risk of separation between the adhesive layer and the foam core. Patent CN115785844A discloses a heat-reducing protective film tape. This method utilizes sodium bicarbonate to decompose upon heating to release carbon dioxide and water. The released carbon dioxide gas causes the colloid to expand, and the generated water is absorbed by bentonite, causing the colloid to expand again. This reduces the contact area between the colloid and the laminated material, reduces viscosity, and achieves a peeling effect. However, this 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 present invention provides a heat-reducing viscosity-reducing pressure-sensitive adhesive, which comprises the following raw materials, measured by weight: 200 to 450 parts of an acrylate polymer solution, 40 to 60 parts of a rubber elastomer, 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 monomer, 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-viscosity-reducing pressure-sensitive adhesive and the solvent in the acrylate polymer solution are the same solvent, which is one or more of benzenes, 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 elastomer is one or more of SBS, SIS, isoprene rubber, styrene-butadiene rubber, natural rubber, and chloroprene rubber, preferably SBS and SIS, and 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 model 920DU20;

[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 according to any of the above schemes, comprising three steps:

[0017] Step 1: Under nitrogen atmosphere, cyclopentadienyl acrylate monomer, ethyl acrylate, and one-third of solvent were added to a four-necked flask and heated to 60-80°C. Half of the initiator was then added dropwise and reacted for 60-120 minutes.

[0018] Step 2: Mix isooctyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate, half of the remaining initiator, and one-third of the solvent, and then add them dropwise to 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 to 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 total amount of 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 sequentially comprises a first release film layer, a heat-reducing viscosity foam layer and a second release film layer; the heat-reducing viscosity foam layer is prepared by coating the above-mentioned heat-reducing viscosity pressure-sensitive adhesive, drying for primary cross-linking, high-temperature foaming, and aging for secondary cross-linking.

[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 heat-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, winding and curing 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 to roll the second release film inward.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention provides a heat-reducing pressure-sensitive adhesive having high viscosity at room temperature and a 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, thereby saving costs. The cyclopentadienyl acrylate monomer in the heat-reducing pressure-sensitive adhesive undergoes a dimerization reaction to form dicyclopentadiene at room temperature, which is polymerized with the acrylate monomer to form a long-chain acrylate polymer. The polymer is cross-linked with a curing agent to form a three-dimensional network structure, which has high viscosity at room temperature. At a high temperature of 170°C, the dicyclopentadiene undergoes a dedimerization reaction to form 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 peel strength of the pressure-sensitive adhesive, thereby achieving the effect of heat-reducing viscosity.

[0027] 2. During the preparation of the heat-reducing viscosity-sensitive adhesive, the rubber elastomer mixture is stirred at high speed to uniformly disperse it in the acrylic polymer solution in the form of small particles; 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 form of the rubber elastomer small particles uniformly dispersed in the heat-reducing viscosity-sensitive adhesive is fixed; at the same time, the introduction of the rubber elastomer in the heat-reducing viscosity-sensitive adhesive makes the acrylic foam adhesive exhibit 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 particles of rubber elastomer are evenly dispersed in the heat-reducing pressure-sensitive adhesive during drying, after high-temperature foaming, the small particles of rubber elastomer 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 has a slow reaction rate. Its cross-linking and 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 cohesion of the adhesive layer, thereby greatly improving the bonding strength of the tape, and achieving high viscosity while also having good strength and impact resistance of the foam tape.

[0030] 5. This integrated foam double-sided tape is made by coating a heat-reducing pressure-sensitive adhesive on a release film and then drying and foaming it. The integrated process ensures 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 following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts 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] Example 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 blowing agent 920DU, 0.03g of curing agent EC303, and 0.07g of curing agent aluminum acetylacetonate.

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

[0038] (1) 20 g of cyclopentadienyl ethyl acrylate, 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., with a stirring speed set at 300 r / min, 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 uniformly added dropwise to the reaction system over 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.

[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), 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, 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-reducing foam adhesive layer through high-temperature foaming. The heat-reducing foam adhesive layer is then attached to the second release film, rolled up, and aged in a drying oven at 48°C for 2 days to obtain an integrated foam double-sided tape.

[0041] Example 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, 0.4g of blowing agent 920DU20, 0.024g of curing agent EC303, and 0.056g of curing agent aluminum acetylacetonate.

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

[0044] (1) 15 g of cyclopentadienyl ethyl acrylate, 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., with a stirring speed set at 300 r / min, 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 uniformly added dropwise to the reaction system over 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.

[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; the stirring speed was then 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), 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.

[0046] (3) The pressure-sensitive adhesive obtained in step (2) is coated on the first release film, 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-reducing foam adhesive layer through high-temperature foaming. The heat-reducing foam adhesive layer is then attached to the second release film, rolled up, and aged in a drying oven at 48°C for 2 days to obtain an integrated foam double-sided tape.

[0047] Example 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 blowing agent 920DU20, 0.039g of curing agent EC303, and 0.091g of curing agent aluminum acetylacetonate.

[0049] The manufacturing method of 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., with a stirring speed set at 300 r / min, 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 uniformly added dropwise to the reaction system over 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, 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-reducing foam adhesive layer through high-temperature foaming. The heat-reducing foam adhesive layer is then attached to the second release film, rolled up, and aged in a drying oven at 48°C for 2 days to obtain an integrated foam double-sided 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 the epoxy curing agent is not added in 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 are 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 are 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] Testing instrument: Rotational rheometer

[0062] First, stack six layers of foam tape together, then create an 8mm diameter disc sample. This is then placed in a rheometer for testing. The temperature sweep is set between -50°C and 150°C, and the storage modulus (G') of the material at 23°C is recorded. The storage modulus (elastic modulus) refers to the amount of energy stored in a material due to elastic (reversible) deformation during deformation, reflecting the material's elasticity.

[0063] 2. Peel force

[0064] Testing equipment: tensile testing machine

[0065] Test method:

[0066] Room-Temperature Peel Strength: Remove the secondary release liner from the foam tape, apply a 50μm PET film, and cut into strips measuring 300mm long by 25.4mm wide. Next, apply these strips to a pre-cleaned SUS steel plate and roll them back and forth twice with a 2kg roller. The test samples are then stored in a standard climate (air, 23°C, 50% relative humidity) for 20 minutes. The resulting strips are then tested using a tensile testing machine.

[0067] High-temperature peel strength: 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 instrument: Drop weight impact tester

[0070] Test method: The film is punched into a 20mm*20mm square sample using a mold, attached to a SUS fixture and held at 10.4Kg for 60 seconds at 70℃. The sample is then placed at room temperature for 48 hours and tested. Repeated tests are performed to determine the energy J required to destroy the sample.

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

[0072] Storage modulus / MPa Room temperature peel strength / gf Peel strength 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: As can be seen from the data in the table, Comparative Example 1 did not use cyclopentadienyl acrylate monomer, so the film did not have a good thermal viscosity reduction effect. Comparative Example 2 did not add rubber elastomer, resulting in poor storage modulus and impact resistance. Comparative Example 3 did not add aluminum acetylacetonate, so the impact resistance of the cured film was poor. Comparative Example 4 did not use epoxy curing agent, so the film could not undergo post-curing reaction, and the cross-linking degree of the film was insufficient, affecting its bonding performance. Although it had 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 descriptions are merely preferred embodiments of the present invention and are 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 will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection 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 elastomer, 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; The acrylate polymer solution comprises the following raw materials in parts by weight: 10-30 parts of cyclopentadienyl acrylate monomer, 10-20 parts of isooctyl acrylate, 20-70 parts of ethyl acrylate, 4-18 parts of methyl methacrylate, 2-15 parts of 2-hydroxyethyl acrylate, 0.1-1 parts of initiator, and 150-350 parts of solvent; The diameter of the foaming agent is 5-9 μm before foaming and 16-30 μm after foaming; The curing agent is an epoxy curing agent and a metal salt curing agent, and the mass ratio of the epoxy curing agent to the metal salt curing agent is 3:7; The cyclopentadiene groups in the cyclopentadienyl acrylate monomers dimerize into a dicyclopentadiene structure. At high temperatures, the dicyclopentadiene structure undergoes a dedimerization reaction to generate cyclopentadiene groups. The long polymer chains break, resulting in partial destruction of the three-dimensional network structure, increased fluidity, narrowed molecular weight distribution, and reduced peel strength of the pressure-sensitive adhesive, thereby achieving thermal viscosity reduction.

2. The heat-reducing pressure-sensitive adhesive according to claim 1, characterized in that: The cyclopentadienyl acrylate monomer is cyclopentadienyl ethyl acrylate.

3. The heat-reducing pressure-sensitive adhesive according to claim 1, characterized in that: The initiator is one or more of cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, azobisisobutyronitrile, azobisisoheptanenitrile, and dimethyl azobisisobutyrate.

4. The heat-reducing pressure-sensitive adhesive according to claim 1, characterized in that: The solvent in the heat-viscosity-reducing pressure-sensitive adhesive and the solvent in the acrylate polymer solution are the same solvent, which is one or more of benzene, alcohol, ester, and ketone.

5. The heat-reducing pressure-sensitive adhesive according to claim 1, characterized in that: The mass ratio of the cyclopentadienyl acrylate monomer, isooctyl acrylate, ethyl acrylate, methyl methacrylate and 2-hydroxyethyl acrylate is (15-25): (15-20): (40-60): (5-15): (5-10).

6. The heat-reducing pressure-sensitive adhesive according to claim 1, characterized in that: The rubber elastomer is one or more of SBS, SIS, isoprene rubber, styrene-butadiene rubber, natural rubber, and chloroprene rubber; The tackifying resin is one or more of rosin resin, petroleum resin, coumarone resin, phenolic resin and terpene resin.

7. A method for preparing a heat-reducing pressure-sensitive adhesive according to any one of claims 1 to 6, characterized in that: Step 1: Under nitrogen atmosphere, add cyclopentadienyl acrylate monomer, ethyl acrylate, and one-third of solvent into a four-necked flask and heat to 60-80°C. Then, add half of the initiator dropwise and react 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 to 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: Dissolve the rubber elastomer and tackifying resin in the remaining 90% solvent and add them to the acrylate polymer solution, 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.

8. 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 by coating, drying, primary cross-linking, high-temperature foaming, and aging for secondary cross-linking the heat-reducing viscosity pressure-sensitive adhesive described in any one of claims 1 to 6.

9. The integrated double-sided foam tape according to claim 8, 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 heat-reducing foam layer is 100-200 μm.

10. A method for preparing the integrated foam double-sided tape according to claim 8 or 9, 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, winding and curing in a drying room, and obtaining an integrated foam double-sided tape.

11. The method for preparing the integrated foam double-sided tape according to claim 10, 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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