Thermal visbreaking PE foam tape and preparation method thereof

Abstract

The invention relates to the field of foam adhesive tapes, in particular to a thermal visbreaking PE foam adhesive tape and a preparation method thereof. Comprising a body, and the body is sequentially provided with a first release layer, a high-viscosity glue layer, a PE foam layer, a thermal reduction glue layer and a release layer from the upper surface to the lower surface. The heat reducing adhesive layer is prepared by coating and curing a reducing adhesive liquid obtained by mixing a prepolymer B, thermal expansion microspheres, an isocyanate cross-linking agent and a solvent; a shell of the thermal expansion microsphere is a vinylidene chloride-acrylonitrile copolymer, and an inner core of the thermal expansion microsphere is a heating expansion agent; the prepolymer B is prepared from the following raw materials in percentage by weight: 70 to 80 parts of 2-ethylhexyl acrylate, 10 to 15 parts of ethyl acrylate, 3 to 8 parts of methacrylic acid, 1 to 3 parts of N-vinyl pyrrolidone, 0.4 to 0.6 part of benzoyl peroxide, 0.2 to 0.4 part of a chain transfer agent and 70 to 90 parts of a solvent. The thermal visbreaking PE foam adhesive tape has the advantages of being capable of being detached again, low in residual adhesive rate and the like.

Description

Technical Field

[0001] The present application relates to the field of foam tapes, and more specifically, to a heat-reduced PE foam tape and a preparation method thereof. Background Art

[0002] In the field of polymer material technology, the development of adhesive materials has gone through a long process, and its importance to industries such as electronic equipment has become increasingly prominent. With the rapid advancement of science and technology, electronic devices such as smartphones are constantly developing in the direction of precision and miniaturization, which makes their precision assembly place more stringent requirements on adhesive materials. High-quality adhesive materials can not only ensure a firm connection between electronic device components, effectively improve the overall stability and reliability of the equipment, so that it can still operate stably in complex usage environments, but also enhance the equipment's seismic and impact resistance to a certain extent. Moreover, in the repair and maintenance of electronic equipment, suitable adhesive materials can greatly reduce the difficulty and cost of repairs, improve repair efficiency, and extend the service life of the equipment. The performance of adhesive materials is directly related to the quality and market competitiveness of electronic equipment. Therefore, the continuous research and development and improvement of adhesive materials has become an important topic in this field.

[0003] Traditionally, various types of double-sided tape have been used to meet the bonding needs of electronic device components, such as smartphones. Traditional double-sided tapes, such as acrylic foam adhesives, are widely used in various bonding scenarios due to their flexibility and good adhesion. Hot melt adhesives, due to their ability to soften when heated, have become an option for solving certain specific bonding problems, playing a role in areas that require temporary fixation or easy disassembly. In addition, some common adhesives, such as epoxy resin adhesives, also provide basic bonding solutions for the assembly of electronic devices in different situations. At the same time, attempts have been made to address bonding and disassembly issues by adding thermally expandable particles to epoxy-acrylic resin adhesives. These traditional adhesive materials and improved methods have provided diverse options for the assembly of electronic devices for a certain period of time.

[0004] However, these conventional means in the prior art have obvious defects. Traditional double-sided adhesives (such as acrylic foam adhesives) are prone to leaving colloid residues on components in high temperature environments or during mechanical disassembly, which may directly cause damage to the components and increase maintenance costs. Although existing hot melt adhesives can be softened by heating, they cannot recover after losing their viscosity under high temperature conditions, presenting an irreversible state. At the same time, there is also the problem of poor resilience, which makes it difficult to meet the requirements for non-destructive disassembly of components during smartphone repairs. The method of adding thermal expansion particles to epoxy-acrylic resin adhesives can achieve thermal expansion disassembly, but it is difficult to achieve multiple thermal expansion disassembly, and residual adhesive is likely to remain after multiple disassembly, and the problem of reduced peel strength will occur when re-adhering. It is also unable to well meet the requirements for non-destructive disassembly and repeated disassembly of components during repairs of electronic devices such as smartphones. Summary of the Invention

[0005] The purpose of the present application is to overcome the above-mentioned technical problems and provide a thermally-reduced viscosity PE foam tape and a preparation method thereof. In the first aspect, a thermally-reduced viscosity PE foam tape comprises a main body, wherein the main body is provided with a first release layer, a high-viscosity adhesive layer, a PE foam layer, a thermally-reduced viscosity layer, and a release layer in sequence from the upper surface to the lower surface; the thermally-reduced viscosity layer is prepared by coating and curing a viscosity-reducing adhesive solution composed of a prepolymer B, heat-expandable microspheres, an isocyanate crosslinker, and a solvent; the shell of the heat-expandable microspheres is a vinylidene chloride-acrylonitrile copolymer, and the core is a heat-expandable agent; the prepolymer B is prepared from the following raw materials in the following weight percentages: 70-80 parts of isooctyl acrylate, 10-15 parts of ethyl acrylate, 3-8 parts of methacrylic acid, 1-3 parts of N-vinyl pyrrolidone, 0.4-0.6 parts of benzoyl peroxide, 0.2-0.4 parts of a chain transfer agent, and 70-90 parts of a solvent.

[0006] By adopting the above technical solution, the 2-EHA / EA / MAA / NVP tetrapolymer produced through the reaction of isooctyl acrylate, ethyl acrylate, methacrylic acid, and N-vinyl pyrrolidone monomers, combined with a chain transfer agent, benzoyl peroxide, and a solvent, can be evenly dispersed with the heat-expandable microspheres. Furthermore, after reaction with an isocyanate crosslinker, the resulting heat-reducing adhesive layer exhibits excellent cohesion and flexibility. This heat-reducing adhesive layer can effectively cope with the expansion stress of the heat-expandable microspheres during expansion and maintains excellent structural stability after expansion, thereby achieving multiple excellent expansion effects. With increasing the number of repeated expansions, the residual adhesive rate during disassembly decreases, allowing the heat-reducing PE foam tape to be quickly removed multiple times with virtually no residual adhesive. Furthermore, the heat-reducing adhesive layer maintains good adhesion stability to the PE foam layer, preventing delamination.

[0007] Specifically, the present application uses 70-80 parts of isooctyl acrylate as the main monomer. Because its molecules contain long-chain branched alkyl groups and the glass transition temperature is as low as -70°C, it gives the adhesive layer ultra-low temperature flexibility, ensuring that the molecular segments are still mobile under -20°C conditions, maintaining initial adhesion ≥15N / 25mm, and at the same time providing a flexible matrix environment for the heat-expandable microspheres to reduce expansion resistance; 10-15 parts of ethyl acrylate are added to adjust the intermolecular force, and its short-chain ester group enhances the cohesive strength, avoiding high-temperature softening caused by excessive isooctyl acrylate, so that the adhesive layer still maintains a shear strength ≥0.8MPa at 120°C to prevent residual glue; 3-8 parts of methacrylic acid contain strongly polar carboxyl groups, which can provide cross-linking sites and polar groups for the surface of the heat-expandable microspheres to form chemical bonds and enhance interfacial bonding (shear strength ≥1.2N / mm 2 ), and at the same time participate in the cross-linking reaction to form a dynamic network. When the microspheres expand at high temperature, the network is reversibly destroyed, and the peeling force is rapidly reduced (80℃ / 5min reduction rate ≥85%); 1-3 parts of N-vinyl pyrrolidone are used as functional monomers, containing a polar five-membered heterocyclic structure, which can improve the polarity of the adhesive layer and promote the uniform dispersion of the heat-expandable microspheres through hydrogen bonding to avoid agglomeration. The prepolymer B made of these ingredients is combined with the heat-expandable microspheres, isocyanate cross-linker, and solvent to form a viscosity-reducing adhesive liquid. The heat-reducing adhesive layer formed after coating and curing has good cohesion and flexibility, can cope with the expansion stress of the heat-expandable microspheres during the expansion process, and can maintain good structural stability after expansion. When it expands again, it can maintain a good expansion effect, so that the heat-reducing PE foam tape can fall off quickly without leaving any residual adhesive. In addition, the heat-reducing adhesive layer and the PE foam layer have good adhesion stability to avoid delamination.

[0008] Preferably, the particle size of the heat-expandable microspheres is 1-5 μm.

[0009] By adopting the above technical solution, the particle size of the heat-expandable microspheres is controlled within 1-5 μm, which allows the heat-expandable microspheres to be better dispersed in the heat-reducing adhesive layer, helping the heat-expandable microspheres to expand evenly when heated, more effectively destroying the contact between the adhesive layer and the adhesive surface, and improving the viscosity-reducing effect of the heat-reducing PE foam tape when heated.

[0010] Preferably, the thermal expansion agent is isobutane.

[0011] By adopting the above technical solution, the heat-expanding microspheres in the heat-reducing adhesive layer of the heat-reducing PE foam tape use the contained isobutane as the heat expansion agent. When the temperature rises, the isobutane vaporizes due to heat and can expand the outer shell of the heat-expanding microspheres, thereby destroying the contact between the adhesive layer and the adhesive surface, greatly reducing the bonding strength, and making the tape easy to tear off with a low residual adhesive rate. It can be repeatedly removed many times and can stably perform its performance in a wide range of temperature environments.

[0012] Preferably, the PE foam layer is a closed-cell foam, and the thickness of the PE foam layer is 180-220 μm; the thickness of the high-viscosity adhesive layer is 40-70 μm; and the thickness of the viscosity-reducing adhesive layer is 30-60 μm.

[0013] The thickness of the closed-cell PE foam layer is 180-220μm, the thickness of the high-viscosity adhesive layer is 40-70μm, and the thickness of the viscosity-reducing adhesive layer is 30-60μm. This reasonable thickness setting enables the performance of each layer of the tape to be fully utilized.

[0014] Preferably, the prepolymer B has a molecular weight of 800,000-1,000,000, a PDI ≤ 2.0, and a Tg of -55-60°C.

[0015] By adopting the above technical solution, the molecular weight of prepolymer B is controlled within the range of 800,000 to 1,000,000, the PDI is ≤ 2.0, and the Tg is -55-60°C. This allows the prepolymer B and the heat-expandable microspheres to be evenly dispersed. Furthermore, the heat-reducing adhesive layer obtained after reaction with the isocyanate cross-linking agent has excellent cohesion and flexibility, can cope with the expansion stress of the heat-expandable microspheres, has a stable structure after expansion, and can maintain a good expansion effect when expanding again, so that the heat-reducing adhesive PE foam tape can be quickly detached without leaving any residual adhesive, and can also ensure stable adhesion between the heat-reducing adhesive layer and the PE foam layer.

[0016] Preferably, the prepolymer B is prepared by the following method: weighing methacrylic acid, N-vinyl pyrrolidone and benzoyl peroxide in parts by weight and mixing them evenly to obtain a mixture A; weighing isooctyl acrylate, ethyl acrylate, methacrylic acid, N-vinyl pyrrolidone and a solvent and mixing them evenly, heating to 68-73° C., and then adding the mixture dropwise in sections, completing the addition within 3-4 hours, raising the temperature to 75-80° C., adding a chain transfer agent and continuing the reaction for 1.5-2.5 hours to obtain a prepolymer B.

[0017] By adopting the above technical solution, the prepolymer B prepared by this method can be uniformly dispersed with the heat-expandable microspheres, and the heat-reducing adhesive layer prepared by combining with the isocyanate cross-linking agent has excellent cohesion and flexibility, can cope with the expansion stress of the heat-expandable microspheres, can maintain structural stability after expansion, and maintain a good expansion effect when expanding again, so that the heat-reducing adhesive PE foam tape can be quickly detached without leaving any residual adhesive, and can also ensure the adhesion stability between the heat-reducing adhesive layer and the PE foam layer.

[0018] Preferably, the high-viscosity layer is prepared by coating and curing a high-viscosity liquid obtained from prepolymer A, a cross-linking agent, and a solvent; the prepolymer A is a BA-MMA-AA-HEMA tetrapolymer.

[0019] By adopting the above technical solution, the high-viscosity adhesive layer formed after the high-viscosity adhesive liquid is cured has stable adhesion to the PE foam tape and has better cohesion, avoiding the phenomenon of residual adhesive remaining on the surface of the adherend after thermal expansion, ensuring that residual adhesive is avoided after multiple thermal expansions, and improving its durability.

[0020] Preferably, the prepolymer A is composed of the following raw materials in parts by weight: 65-75 parts of butyl acrylate, 10-15 parts of methyl methacrylate, 5-10 parts of acrylic acid, 2-5 parts of hydroxyethyl methacrylate, 0.5-0.8 parts of azobisisobutyronitrile, 0.1-0.3 parts of a chain transfer agent, and 60-80 parts of a solvent; the prepolymer A is prepared by the following method: weighing acrylic acid, hydroxyethyl methacrylate, and azobisisobutyronitrile and mixing them uniformly to obtain a mixture B; weighing butyl acrylate, methyl methacrylate, and a solvent and mixing them uniformly, heating to 70-80° C., adding the mixture dropwise in sections over 1.5-2.5 hours, heating to 80-90° C. after the addition is complete, adding the chain transfer agent in sections, and reacting for 5-6 hours to obtain the prepolymer A.

[0021] By adopting the above technical solution, the prepared prepolymer A can ensure that the high-viscosity adhesive layer formed after the high-viscosity adhesive liquid is cured adheres stably to the PE foam tape, ensure the structural stability of the heat-reduced PE foam adhesive, cope with the particularity of multiple thermal expansion and disassembly, ensure that residual adhesive remains on the surface of the adherend after multiple thermal expansions, ensure that the heat-reduced adhesive layer is easy to fall off after multiple thermal expansions and avoid the possibility of residual rate, thereby improving durability.

[0022] Preferably, the prepolymer A has a molecular weight of 1.2-1.5 million, a PDI ≤ 2.5, and a Tg of -45-50°C.

[0023] By adopting the above technical solution, the high-viscosity adhesive layer formed by curing the high-viscosity adhesive liquid prepared with the participation of prepolymer A has stable adhesion to the PE foam tape and has good cohesive force. It can cope with the particularity of multiple thermal expansion and disassembly, ensure that residual adhesive remains on the surface of the adherend after multiple thermal expansions, ensure that the heat-reduced adhesive layer can be easily detached after multiple thermal expansions and avoid the possibility of residual rate, thereby improving its durability.

[0024] In the second aspect, a preparation method of a heat-reducing PE foam tape is prepared by the following method: weighing prepolymer B and heat-expanding microspheres in parts by weight and mixing them to evenly disperse the heat-expanding microspheres, then adding a cyanate crosslinking agent and mixing them evenly, and finally adding a solvent for dilution to obtain a viscosity-reducing adhesive; applying a high-viscosity adhesive liquid on a first release layer, curing and shaping it, cooling it and laminating it to one side of a PE foam layer to obtain a foam-high-viscosity composite layer; applying the viscosity-reducing adhesive liquid on a second release layer, curing and shaping it, cooling it and laminating it to the side of the PE foam layer of the foam-high-viscosity composite layer away from the high-viscosity layer to obtain a semi-finished product, and then aging it to obtain a heat-reducing PE foam tape.

[0025] By adopting the above technical solution, prepolymer B, heat-expandable microspheres, isocyanate cross-linking agent and solvent are mixed according to specific steps to prepare a viscosity-reducing adhesive material, which can make the heat-expandable microspheres uniformly dispersed in the viscosity-reducing adhesive layer; the high-viscosity adhesive liquid is applied to the first release layer and laminated with the PE foam layer to form a foam-high-viscosity composite layer, thereby ensuring stable adhesion between the high-viscosity adhesive layer and the PE foam layer; the viscosity-reducing adhesive liquid is applied to the second release layer and laminated with the foam-high-viscosity composite layer and then cured, so that the layers of the heat-reducing PE foam tape can be tightly bonded and structurally stable, and can maintain strong bonding strength at room temperature. When the temperature is increased, the heat-expandable microspheres play a role in causing the bonding strength to drop sharply, thereby achieving easy tearing, low adhesive residue rate and a high number of repeated disassembly times, thereby improving the reliability of bonding and rework of electronic equipment.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. The 2-EHA / EA / MAA / NVP tetrapolymer prepared by reacting isooctyl acrylate, ethyl acrylate, methacrylic acid, and N-vinyl pyrrolidone monomers with a chain transfer agent, benzoyl peroxide, and solvent can be evenly dispersed with heat-expandable microspheres. After reacting with an isocyanate crosslinker, the heat-reducing adhesive layer has excellent cohesion and flexibility, which can cope with the expansion stress of heat-expandable microspheres. After expansion, the structure is stable, allowing the heat-reducing PE foam tape to fall off quickly without leaving any adhesive residue. 2. Using heat-expandable microsphere technology, it maintains strong bonding strength at room temperature. When the temperature rises to 70-90℃, the microspheres expand and destroy the contact area of ​​the adhesive layer, causing a sharp drop in bonding strength, making it easy to tear off. The residual adhesive rate is ≤3%, and it can be repeatedly removed ≥5 times. It can perform stably in wide and narrow temperature environments, improving the reliability of electronic equipment bonding and repair. DETAILED DESCRIPTION

[0027] The present application is further described in detail below with reference to the embodiments.

[0028] Introduction of some raw materials: Heat-expandable microspheres are produced using suspension polymerization technology. The principle is to add monomers, initiators, and dispersants to water, stir, and form suspended droplets. Free radical polymerization occurs within the droplets to produce polymer particles. Heat-expandable microspheres require a foaming agent to be encapsulated within a polymer shell, forming a core-shell structure.

[0029] The thermal expansion microspheres are made of vinylidene chloride-acrylonitrile copolymer as the outer shell, and the polymerization degree of the vinylidene chloride-acrylonitrile copolymer is 3000-5000; the content of acrylonitrile in the copolymer is 40%-60%, and the content of vinylidene chloride is 40%-60%. Example

[0030] Example 1 A heat-reducing PE foam tape comprises a main body, on which a first release layer, a high-viscosity layer, a PE foam layer, a heat-reducing viscous layer, and a release layer are sequentially provided from the upper surface to the lower surface; the PE foam layer is a closed-cell foam, and the thickness of the PE foam layer is 180-220 μm; the thickness of the high-viscosity layer is 40-70 μm; the thickness of the reducing viscous layer is 30-60 μm; in this application, the thickness of the PE foam layer is preferably 200 μm; the thickness of the high-viscosity layer is 50 μm; the thickness of the reducing viscous layer is 50 μm; the first release layer and the second release layer are both double-coated double-silicone release paper, and the double-coated double-silicone release paper has a gram weight of 120g, and is double-sided coated silicone oil paper.

[0031] The heat-reducing PE foam tape is prepared by the following method: Prepolymer A is a BA / MMA / AA / HEMA tetrapolymer with a molecular weight of 1.2-1.5 million, a PDI ≤ 2.5, and a Tg of -45-50°C. The specific preparation method of the prepolymer A is as follows: According to parts by weight, acrylic acid, hydroxyethyl methacrylate and azobisisobutyronitrile were weighed and mixed evenly to obtain a mixture B; butyl acrylate, methyl methacrylate and solvent (ethyl acetate) were weighed and put into a reaction kettle for even mixing, the temperature was raised to 75°C, and the mixture B was added dropwise in sections within 2 hours. After the dropwise addition was completed, the temperature was raised to 85°C, and a chain transfer agent (dodecanethiol) was added in 3 sections, each section was separated by 2 hours, and the amount added each time was the same. The addition reaction time periods were 0 hours, 2 hours and 4 hours respectively. When the reaction was carried out for 6 hours, the heating reaction was stopped, and the material was cooled and discharged to obtain a prepolymer A.

[0032] Prepolymer B is a 2-EHA / EA / MAA / NVP tetrapolymer with a molecular weight of 800,000-1,000,000, PDI ≤ 2.0, and Tg = -55-60°C. The specific preparation method of the prepolymer A is as follows: Methacrylic acid, N-vinyl pyrrolidone and benzoyl peroxide were weighed in parts by weight and mixed uniformly to obtain a mixture A; isooctyl acrylate, ethyl acrylate, methacrylic acid, N-vinyl pyrrolidone and a solvent (ethyl acetate) were weighed and placed in a reaction kettle for uniform mixing, heated to 70° C., and then the mixture A was added dropwise in three sections, with the same parts by weight added in each section and an interval of 1 hour between each section. The first section was a reaction time of 0 hour, and the addition was completed within 3 hours. The temperature was raised to 75° C., isooctyl thioglycolate was added, and the reaction was continued for 2 hours. The heating reaction was stopped, and the material was cooled and discharged to obtain a prepolymer B.

[0033] Prepolymer B and heat-expandable microspheres were weighed and mixed according to parts by weight to uniformly disperse the heat-expandable microspheres. A cyanate crosslinking agent (HDI trimer, NCO content 12-15%, measured 13.2%) was then added and mixed uniformly. Finally, a solvent (ethyl acetate) was added for dilution to obtain a viscosity-reducing adhesive. The particle size of the heat-expandable microspheres was 1-5 μm, and in this embodiment, 5 μm. The heat-expandable agent was isobutane, and the shell of the heat-expandable microspheres was a vinylidene chloride-acrylonitrile copolymer with a shell thickness of 1 μm. Prepolymer A, a crosslinking agent, and a solvent (butyl acetate) were weighed and mixed uniformly to obtain a high-viscosity adhesive solution.

[0034] Apply the high-viscosity adhesive liquid on the first release layer, cure and shape it (bake at 120°C for 3 minutes), cool it, and then adhere it to one side of the PE foam layer to obtain a foam-high-viscosity composite layer; The viscosity-reducing adhesive liquid is coated on the second release layer, cured and shaped (baked at 120°C for 3 minutes), and after cooling, adhered to the side of the PE foam layer of the foam-high-viscosity composite layer away from the high-viscosity layer to obtain a semi-finished product, which is then aged (60°C for 30 hours) to obtain a heat-reduced viscosity PE foam tape.

[0035] Example 2-3 The difference between Example 2-3 and Example 1 is that the amounts of raw materials used are different, as shown in Table 1; Table 1 Amount of raw materials used in Examples 1-3 (parts by weight) Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that prepolymer B is prepolymer A.

[0036] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that the prepolymer B is replaced by an equal amount of modified epoxy acrylate (brand model LENCOLO, L-6112C).

[0037] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that an equal amount of N-vinyl pyrrolidone is replaced by methacrylic acid.

[0038] Comparative Example 4 The difference between Comparative Example 4 and Example 2 is that an equal amount of isooctyl acrylate is replaced by ethyl acrylate.

[0039] Comparative Example 5 The difference between Comparative Example 5 and Example 2 is that the amounts of raw materials used are different. Specifically, based on parts by weight, the amount of isooctyl acrylate used is 12 parts, and the amount of ethyl acrylate used is 75 parts.

[0040] Performance testing The thermally debonding PE foam tapes obtained in Examples 1-3 and Comparative Examples 1-5 were subjected to the following performance tests, which were mainly aimed at the thermally debonding layer.

[0041] Detection method / test method Sample 1: the heat-detackifying PE foam tape obtained in Examples 1-3 and Comparative Examples 1-4.

[0042] Sample 2: The heat-reducing PE foam tape obtained in Examples 1-3 and Comparative Examples 1-4 was cut into samples with a length of 5 cm and a width of 2 cm, and a peeling test was performed: the sample was stably attached to the surface of a neat aluminum alloy shell with a bonding force of 5 N and a bonding time of 1 min, and then heated to 80°C for thermal expansion disassembly with a disassembly force of 10 N. After cooling, Sample 2 was obtained.

[0043] Sample 3: Sample 2 was subjected to a cyclic peeling test, and sample 3 was obtained after the above peeling test process was repeated 5 times.

[0044] Sample 4: The heat-reduced PE foam tape obtained in Examples 1-3 and Comparative Examples 1-4 was cut into samples with a length of 10 cm and a width of 5 cm, placed in an aging test chamber at 85°C / 85% RH, aged for 1000 h, cooled and dried to obtain Sample 4.

[0045] 1) Samples 1 and 4 were tested for their average linear expansion coefficients according to GB / T 2572-2008; the ratio of the average linear expansion coefficient of sample 4 to the average linear expansion coefficient of sample 1 was multiplied by 100% to obtain the corresponding aging retention rate (%). When the aging retention rate (%) was lower than 90%, it was considered unqualified, and higher than or equal to 90%, it was considered qualified.

[0046] 2) Heat Sample 1 to 80°C and then test the peel strength in accordance with GB / T 2792-2014. Maintain the temperature at 80°C during the test. Calculate the peel strength drop as 1-(the peel strength of Sample 1 heated to 80°C divided by the peel strength of Sample 1 multiplied by 100%). A peel strength drop greater than 85% is designated as Grade A, a peel strength drop ≤ 85% is designated as Grade B, and a peel strength drop below 75% is designated as Grade C. A higher peel strength indicates greater ease of peeling at 80°C.

[0047] Sample 1 and sample 3 are attached to the clean surface of the aluminum alloy shell again and then peeled off under the same conditions as above. Then, their residual glue rates are calculated respectively, and then the change in residual glue rate is calculated. The change in residual glue rate is equal to the residual glue rate of sample 3 minus the residual glue rate of sample 1. When the change in residual glue rate is ≤0.5%, it is recorded as level I; 0.5% < change in residual glue rate ≤1%, it is recorded as level II; 1% < change in residual glue rate ≤2%, it is recorded as level III; 2% < change in residual glue rate ≤3%, it is recorded as level VI; the change in residual glue rate >3% is recorded as level V. The higher the level, the greater the probability of residue after multiple expansion and disassembly; and when the residual glue rate of sample 1 is ≤3%, it is recorded as qualified, otherwise it is unqualified.

[0048] The above data were conducted 3 times and the average value was taken, as shown in the following table; Table 1 Experimental data of Examples 1-3 and Comparative Examples 1-5 Combining Example 2 and Comparative Examples 1-5 and Table 1, it can be seen that the peel strength of Comparative Examples 1-2 is as low as below 18N / 25mm, and the aging retention rate (less than 90%) and the residual glue rate of Sample 1 (greater than 3%) are unqualified, and the decline rate grade is reduced from Grade A (decline rate greater than 85%) to Grade C (decline rate less than 75%); the change in the residual glue rate increases, and its grade increases from Grade I (residual glue rate change ≦0.5%) to Grade VI (2%<residual glue rate change ≦3%) or Grade V (residual glue rate change>3%). It can be seen that as the number of disassembly increases, the change in the residual glue rate is larger. In summary, it can be seen that the 2-EHA / EA / MAA / NVP tetrapolymer prepared by reacting the monomers of isooctyl acrylate, ethyl acrylate, methacrylic acid, and N-vinyl pyrrolidone in the present application, in combination with a chain transfer agent, benzoyl peroxide, and a solvent, can be uniformly dispersed with the heat-expandable microspheres, and after reacting with the isocyanate crosslinker, the heat-reducing adhesive layer has excellent cohesion and flexibility, can cope with the expansion stress of the heat-expanding microspheres, and has a stable structure after expansion, which allows the heat-reducing adhesive PE foam tape to fall off quickly without leaving any residual adhesive.

[0049] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A heat-reducing PE foam tape, comprising a body, characterized in that: The main body is provided with a first release layer, a high-viscosity adhesive layer, a PE foam layer, a heat-reducing adhesive layer, and a release layer in order from the upper surface to the lower surface; the heat-reducing adhesive layer is prepared by coating and curing a viscosity-reducing adhesive solution composed of prepolymer B, heat-expanding microspheres, an isocyanate crosslinking agent, and a solvent; the shell of the heat-expanding microspheres is a vinylidene chloride-acrylonitrile copolymer, and the core is a heat-expanding agent; the prepolymer B is prepared from the following raw materials in the following weight percentages: 70-80 parts of 2-ethylhexyl acrylate 10-15 parts of ethyl acrylate 3-8 parts of methacrylic acid 1-3 parts N-vinyl pyrrolidone 0.4-0.6 parts of benzoyl peroxide Chain transfer agent 0.2-0.4 parts 70-90 parts of solvent.

2. The heat-reducing PE foam tape according to claim 1, characterized in that: The particle size of the thermally expandable microspheres is 1-5 μm.

3. The heat-reducing PE foam tape according to claim 1, characterized in that: The thermal expansion agent is isobutane.

4. The heat-reducing PE foam tape according to claim 1, characterized in that: The PE foam layer is a closed-cell foam with a thickness of 180-220 μm; the high-viscosity layer has a thickness of 40-70 μm; and the viscosity-reducing layer has a thickness of 30-60 μm.

5. The heat-reducing PE foam tape according to claim 1, characterized in that: The prepolymer B has a molecular weight of 800,000-1,000,000, PDI≤2.0, and Tg=-55-60°C.

6. The heat-reducing PE foam tape according to claim 1, characterized in that , the prepolymer B is prepared by the following method: Methacrylic acid, N-vinyl pyrrolidone, and benzoyl peroxide were weighed in parts by weight and mixed evenly to obtain a mixture A; isooctyl acrylate, ethyl acrylate, methacrylic acid, N-vinyl pyrrolidone, and a solvent were weighed and mixed evenly, heated to 68-73° C., and then the mixture A was added dropwise in sections within 3-4 hours. The temperature was raised to 75-80° C., a chain transfer agent was added, and the reaction was continued for 1.5-2.5 hours to obtain a prepolymer B.

7. The heat-reducing PE foam tape according to claim 1, characterized in that: The high-viscosity layer is prepared by coating and curing a high-viscosity liquid obtained from prepolymer A, a crosslinking agent, and a solvent; the prepolymer A is a BA-MMA-AA-HEMA tetrapolymer.

8. The heat-reducing PE foam tape according to claim 7, characterized in that: The prepolymer A is composed of the following raw materials in parts by weight: 65-75 parts of butyl acrylate 10-15 parts of methyl methacrylate 5-10 parts of acrylic acid 2-5 parts of hydroxyethyl methacrylate 0.5-0.8 parts of azobisisobutyronitrile Chain transfer agent 0.1-0.3 parts 60-80 parts of solvent.

9. The heat-reducing PE foam tape according to claim 7, characterized in that: The molecular weight is 1.2-1.5 million, PDI≤2.5, and Tg=-45-50°C.

10. A method for preparing the heat-reducing PE foam tape according to any one of claims 1 to 9, characterized in that: Prepared by the following method: Prepolymer B and heat-expandable microspheres were weighed and mixed according to parts by weight to uniformly disperse the heat-expandable microspheres, and then a cyanate crosslinker was added and mixed evenly, and finally a solvent was added to dilute the mixture to obtain a viscosity-reducing rubber compound; Applying a high-viscosity adhesive liquid on the first release layer, solidifying and shaping it, and laminating it to one side of the PE foam layer after cooling to obtain a foam-high-viscosity composite layer; The viscosity-reducing adhesive liquid is coated on the second release layer, solidified and shaped, and then adhered to the side of the PE foam layer of the foam-high-viscosity composite layer away from the high-viscosity layer after cooling to obtain a semi-finished product, which is then aged to obtain a heat-reduced viscosity PE foam tape.

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