Viscosity-controllable thermal visbreaking foam tape and preparation method thereof

Abstract

The invention discloses a viscosity-controllable thermal visbreaking foam tape and a preparation method thereof. The viscosity-controllable thermal visbreaking foam tape comprises a foam base material layer, a permanent bonding pressure-sensitive adhesive layer and a viscosity-controllable thermal visbreaking pressure-sensitive adhesive layer, wherein the permanent bonding pressure-sensitive adhesive layer is positioned on the first surface of the foam base material layer; and the viscosity-controllable thermal visbreaking pressure-sensitive adhesive layer is positioned on the second surface of the foam base material layer. The viscosity-controllable thermal visbreaking foam tape has good impact resistance, the waterproof performance can reach the IPX8 level, and meanwhile, the viscosity-controllable thermal visbreaking foam tape has good anti-warping performance. Through special formula design, the prepared thermal visbreaking foam tape also has the performance that the viscosity is controllable at different temperatures, the controllable viscosity characteristic can enable the viscosity to be reduced after high-temperature heating and the effect of convenient disassembly when disassembly, maintenance and rework are needed, and meanwhile, in the daily use process, the thermal visbreaking foam tape has the advantages that the thermal visbreaking foam tape is convenient to disassemble, maintain and rework. And the risk of bonding failure in a medium-temperature environment can be effectively prevented.

Description

Technical Field

[0001] The invention relates to the field of thermally-reduced viscosity foam adhesive materials, and in particular to a thermally-reduced viscosity foam adhesive tape with controllable viscosity and a preparation method thereof. Background Art

[0002] In order to reduce the thickness of the mobile phone, the solution adopted by the mobile phone designer is to glue the back cover and the middle frame instead of the previous snap-on design. Of course, the bonding scheme varies according to the needs of the mobile phone design.

[0003] The main materials of the back cover of mobile phones are mainly glass and plastic, supplemented by ceramics, and niche varieties such as leather and carbon fiber. Among them, glass is widely used in smart phones, tablets and other fields due to its high hardness, high strength, scratch resistance, dirt resistance, and excellent feel. Currently, high-end mobile phones all use glass as the back cover material. On the other hand, the composition of glass also puts forward higher requirements for the anti-drop performance of electronic products. Therefore, existing smart display devices mostly use double-sided tape with foam structure to bond components, and achieve the anti-drop effect through the cushioning effect of foam.

[0004] In addition, today's smart display and communication equipment have a high value and need to be repaired and maintained. Currently, there is a method on the market that heats the tape to a certain temperature to reduce the stickiness of the tape, thereby facilitating disassembly. However, this type of tape usually has a very low viscosity under high temperature conditions, and the viscosity cannot be specifically designed and regulated for the actual use environment, resulting in the risk of bonding failure in the final product.

[0005] In view of the above problems, the present invention provides a heat-resistant and anti-viscosity foam tape with controllable viscosity, which is used for bonding the front cover, back cover and other parts of electronic display devices. While providing efficient bonding performance, it also has the property of controllable viscosity at different temperatures, effectively preventing the risk of bonding failure in high temperature environment. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a foam tape with controllable heat-reducing viscosity and a preparation method thereof in view of the deficiencies in the above-mentioned prior art.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: In the first aspect of the present invention, a viscous and heat-controlled viscosity-reducing foam tape is provided, comprising: a foam substrate layer, a permanent bonding pressure-sensitive adhesive layer located on a first surface of the foam substrate layer, and a viscous and heat-controlled viscosity-reducing pressure-sensitive adhesive layer located on a second surface of the foam substrate layer;

[0008] The controllable heat-reducing viscosity pressure-sensitive adhesive layer is obtained by coating a controllable heat-reducing viscosity pressure-sensitive adhesive and then curing it. The raw materials for preparing the controllable heat-reducing viscosity pressure-sensitive adhesive include, by weight: 100 parts of a high molecular polymer, 5 to 50 parts of a tackifying resin, 1.5 to 6 parts of a curing agent, and 20 to 50 parts of a first solvent.

[0009] Preferably, the high molecular polymer is obtained by polymerizing monomers under the action of an initiator, and its preparation raw materials include, by weight: 30-130 parts of soft monomers, 10-40 parts of hard monomers, 2-10 parts of functional monomers, 80-320 parts of a second solvent, and 0.5-3 parts of an initiator.

[0010] Preferably, the soft monomer is one or more of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and lauryl methacrylate;

[0011] The hard monomer is one or more of acrylonitrile, vinyl acetate, acrylamide, styrene, methyl methacrylate, methyl acrylate, furfural-based monomer tetrahydrofurfuryl methacrylate, disproportionated rosin-modified monomer.

[0012] The functional monomer is one or more of methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, acrylamide, N-hydroxymethyl acrylamide, glycidyl methacrylate, and maleic anhydride.

[0013] Preferably, the initiator is one or more of dibenzoyl peroxide, azobisisobutyronitrile, 2-methyl-2-n-butyltellurium-propionic acid, (methyltellurium-methyl)benzene, 1-chloro-4-(methyltellurium-methyl)benzene, 1-hydroxy-4-(methyltellurium-methyl)benzene, 1-phenoxycarboxyl-4-(2-methyltellurium-propyl)benzene, dimethyl ditellurium compounds, and diethyl ditellurium compounds;

[0014] The second solvent is one or more of toluene, ethyl acetate and butanone.

[0015] Preferably, the high molecular weight polymer is prepared by the following method:

[0016] In an atmosphere of nitrogen protection, the soft monomer, the hard monomer, the functional monomer and the second solvent are mixed, stirred evenly at room temperature, and then part of the initiator is added, the temperature is raised to 60-70°C, and the reaction is stirred for 4-10 hours; the remaining part of the initiator is added, the temperature is raised to 80-87°C, the reaction is carried out for 1-4 hours, and the second solvent is added for dilution to obtain the high molecular polymer.

[0017] Preferably, the tackifying resin is selected from one or more of rosin resins, modified rosin resins, terpene resins and derivatives thereof, phenolic resins, aliphatic petroleum resins, aromatic petroleum resins, and aliphatic and aromatic mixed petroleum resins.

[0018] Preferably, the curing agent is selected from one or more of isocyanates, epoxies, metal salts, and nitrogen pyridines;

[0019] The first solvent is one or more of toluene, ethyl acetate and butanone.

[0020] Preferably, the raw materials for preparing the controllable-tack thermally-reduced pressure-sensitive adhesive layer further include an auxiliary agent, and the auxiliary agent is selected from one or more of a color paste, a surfactant, an antistatic agent, and a coupling agent.

[0021] Preferably, the material of the foam substrate layer is one or more of polyethylene foam, acrylic foam, polypropylene foam, and polyurethane foam.

[0022] A second aspect of the present invention provides a method for preparing the above-mentioned controllable heat-reducing adhesive foam tape, comprising the following steps:

[0023] S1, applying glue on the release substrate to form a permanent adhesive pressure-sensitive adhesive layer after drying, and laminating the adhesive surface to the first surface of the foam substrate layer to obtain an intermediate product;

[0024] S2. Coating a viscous and controllable heat-reducing pressure-sensitive adhesive on the release substrate to form a viscous and controllable heat-reducing pressure-sensitive adhesive layer after drying, and laminating the adhesive surface to the second surface of the foam substrate layer to obtain the viscous and controllable heat-reducing foam tape.

[0025] The beneficial effects of the present invention are:

[0026] The present invention provides a heat-reduced viscosity foam tape with controllable viscosity and a preparation method thereof. The heat-reduced viscosity foam tape with controllable viscosity has good impact resistance, and its waterproof performance can reach the IPX8 level, and it also has good anti-warping performance. The tape product can be used for bonding the front cover, the back cover, etc. of an electronic display device, and can provide efficient bonding performance, so that the electronic display device has good comprehensive performance such as impact resistance and waterproof performance.

[0027] The invention adopts a special formula design to make the prepared heat-reduced viscosity foam tape have the property of controllable viscosity at different temperatures. Specifically, at room temperature, the peel strength can reach more than 20N / inch, at medium temperature, such as 55°C, the peel strength can reach more than 10N / inch, and at high temperature, such as 75°C*10min, the peel strength is controlled within the range of 1 to 3N / inch. This controllable viscosity property can reduce the viscosity after high-temperature heating when disassembly, repair and rework are required, which facilitates disassembly. At the same time, in daily use, it can effectively prevent the risk of adhesive failure in medium temperature environment. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0029] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0030] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0031] The invention provides a viscous and heat-controllable anti-viscosity foam tape, comprising: a foam substrate layer, a permanent bonding pressure-sensitive adhesive layer located on a first surface of the foam substrate layer, and a viscous and heat-controllable anti-viscosity pressure-sensitive adhesive layer located on a second surface of the foam substrate layer.

[0032] The positions of the permanent adhesive layer and the adhesive controllable heat-reducing adhesive layer can be exchanged according to the actual use process. In addition, a double-sided release layer can be provided on one side of the pressure-sensitive adhesive layer, or release layers can be provided on the two pressure-sensitive adhesive layers.

[0033] The release layer can be a commonly used silicone release material in the industry, and its function is to facilitate operations such as winding, unwinding, and die-cutting. The material of the release material can be plastic film, paper, etc. The present invention does not specifically limit its type and thickness. However, in order to better achieve the effect of winding and unwinding, a release material with a release force in the range of 5 to 40 gf / inch is preferred. Too small a release force will result in poor adhesion to the pressure-sensitive adhesive layer, and too large a release force will result in deformation of the tape sample during unwinding and peeling, making it difficult to peel off, etc.

[0034] The controllable heat-reducing viscosity pressure-sensitive adhesive layer is obtained by coating the controllable heat-reducing viscosity pressure-sensitive adhesive and then curing it. The raw materials for preparing the controllable heat-reducing viscosity pressure-sensitive adhesive include, by weight: 100 parts of high molecular polymer, 5-50 parts of tackifying resin, 1.5-6 parts of curing agent, and 20-50 parts of first solvent.

[0035] In a preferred embodiment, the material of the foam substrate layer is one or more of polyethylene foam, acrylic foam, polypropylene foam, and polyurethane foam. From the perspective of waterproofness, cohesive strength, and buffering, closed-cell high-density polyethylene foam and acrylic foam are more preferred, and high-density polyethylene foam is further preferred.

[0036] In a preferred embodiment, the high molecular polymer is obtained by polymerizing monomers under the action of an initiator, and its preparation raw materials include, by weight: 30-130 parts of soft monomers, 10-40 parts of hard monomers, 2-10 parts of functional monomers, 80-320 parts of a second solvent, and 0.5-3 parts of an initiator.

[0037] In order to make the final pressure-sensitive adhesive have good initial adhesion, peeling force and cohesion and other comprehensive properties, there are certain requirements for the type and proportion of acrylic monomers selected for the preparation of polymers. In addition, there are certain requirements for the weight average molecular weight of the prepared polymer. From the results, the weight average molecular weight range of the polymer is preferably 400,000 to 850,000, and the molecular weight distribution is between 3.0 and 5.0. When the weight average molecular weight is too low, the glue molecular chain is too short, and the cohesive performance of the pressure-sensitive adhesive prepared using such a polymer is too low, resulting in poor temperature resistance and shear resistance of the tape, which is not suitable for the use of the invention's controllable viscosity heat-reducing pressure-sensitive adhesive; when the weight average molecular weight is too high, the cohesive performance of the glue will be significantly improved, but from the perspective of the wetting of the pressure-sensitive adhesive, the wetting performance of the tape for the attached object will deteriorate, especially for some low surface energy, rough attached objects, the wetting performance of the tape will deteriorate, which is easy to cause poor bonding and the risk of degumming from the substrate, which is not conducive to the processing and use of the tape. Similarly, when the molecular weight distribution is too wide, the cohesive performance of the glue is too low; when the molecular weight distribution is too narrow, the initial adhesion performance of the glue will be affected. Through continuous experimental exploration, the present invention preferably has a molecular weight distribution range of 3.0 to 5.0.

[0038] In a preferred embodiment, the soft monomer is one or more of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and lauryl methacrylate; the soft monomer is the main monomer for preparing pressure-sensitive adhesives, and its function is to produce polymers with low glass transition temperature and initial adhesion.

[0039] In a preferred embodiment, the hard monomer is one or more of acrylonitrile, vinyl acetate, acrylamide, styrene, methyl methacrylate, methyl acrylate, furfural-based monomer tetrahydrofurfuryl methacrylate, and disproportionated rosin-modified monomer, and its function is to improve the cohesive strength of the polymer.

[0040] Functional monomers, also called functional monomers, are olefin monomers with various functional groups and copolymerizable with soft monomers, which can cause a certain degree of crosslinking of the pressure-sensitive adhesive, thereby greatly improving the cohesive strength, heat resistance and aging resistance. Preferably, the monomers are one or more of methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, acrylamide, N-hydroxymethyl acrylamide, glycidyl methacrylate and maleic anhydride.

[0041] The initiator may be a polymerization initiator such as a peroxide compound, an azo compound, an organic tellurium compound, etc. For example, in a preferred embodiment, the initiator is one or more of dibenzoyl peroxide, azobisisobutyronitrile, 2-methyl-2-n-butyltellurium-propionic acid, (methyltellurium-methyl) benzene, 1-chloro-4-(methyltellurium-methyl) benzene, 1-hydroxy-4-(methyltellurium-methyl) benzene, 1-phenoxycarboxyl-4-(2-methyltellurium-propyl) benzene, dimethyl ditellurium compounds, and diethyl ditellurium compounds.

[0042] In a preferred embodiment, the second solvent is one or more of toluene, ethyl acetate, and butanone.

[0043] In a preferred embodiment, the high molecular weight polymer is prepared by the following method:

[0044] In an atmosphere of nitrogen protection, the soft monomer, hard monomer, functional monomer and the second solvent are mixed, stirred evenly at room temperature, and then part of the initiator is added, the temperature is raised to 60-70°C, and the reaction is stirred for 4-10 hours; the remaining part of the initiator is added, the temperature is raised to 80-87°C, the reaction is carried out for 1-4 hours, and the second solvent is added for dilution to obtain a high molecular polymer.

[0045] In a preferred embodiment, the tackifying resin is selected from one or more of rosin resin, modified rosin resin, terpene resin and its derivatives, phenolic resin, aliphatic petroleum resin, aromatic petroleum resin, and aliphatic and aromatic mixed petroleum resin. From the perspective of compatibility, the present invention is more preferably modified rosin and terpene phenol resins, and these resins can be obtained by commercial means. The addition ratio of the tackifying resin is 5 to 50 parts by weight. When a compounding method of multiple resins is adopted, the total amount of added resin should not exceed 50 parts by weight. When the resin content is higher than 50 parts by weight, the pressure-sensitive adhesive will be hard as a whole, and it will not be able to exert good wetting properties, and thus it will not be able to exert good bonding properties; when the resin content is lower than 5 parts by weight, the molecular chain segments of the polymer cannot be fully unfolded due to the lack of tackifying resin, and it is also impossible to exert good wetting properties, and thus it is impossible to exert good bonding properties. In addition, the tackifier resin with controllable viscosity provided by the present invention also has certain requirements for the softening point of the tackifier resin. For the tackifier resin with a softening point lower than 100°C, due to its poor temperature resistance, the fluidity becomes stronger under high temperature conditions. As a result, when in a high temperature environment, the peeling force of the adhesive layer will show a downward trend; for the tackifier resin with a softening point higher than 100°C, due to its good temperature resistance, under high temperature conditions, such as the temperature of about 75°C required by the present invention, the morphology of the tackifier resin does not change significantly. As a result, when in a high temperature environment, the peeling force of the adhesive layer does not change much. For the tackifier resin used in the tackifier resin layer with controllable viscosity provided by the present invention, in order to better achieve the peeling force requirements at different temperatures, it is preferred to use a combination of tackifier resins with high softening points and low softening points.

[0046] The curing agent may be one or more of isocyanate, epoxy, metal salt, nitrogen pyridine and the like, and the present invention does not specifically limit it, but from the perspective of high temperature resistance and high cohesion, isocyanate and epoxy curing agents are preferred. These curing agents can be obtained by common commercial methods.

[0047] The first solvent is one or more of toluene, ethyl acetate, and butanone. The present invention does not specifically limit the solvent used, but ethyl acetate is preferred from the perspectives of odor and environmental protection.

[0048] In a preferred embodiment, the raw materials for preparing the controllable heat-reducing viscosity pressure-sensitive adhesive layer also include an auxiliary agent, which is selected from one or more of a color paste, a surfactant, an antistatic agent, and a coupling agent. The auxiliary agent can be added specifically according to actual application requirements, and the present invention does not make any special restrictions on it.

[0049] The present invention also provides a method for preparing the above-mentioned controllable heat-reducing adhesive foam tape, comprising the following steps:

[0050] S1, applying glue on the release substrate to form a permanent adhesive pressure-sensitive adhesive layer after drying, and laminating the adhesive surface to the first surface of the foam substrate layer to obtain an intermediate product;

[0051] S2. Coating a viscous controllable heat-reducing pressure-sensitive adhesive on the release substrate to form a viscous controllable heat-reducing pressure-sensitive adhesive layer after drying, and laminating the adhesive surface to the second surface of the foam substrate layer to obtain a viscous controllable heat-reducing foam tape.

[0052] In terms of performance, the controllable viscosity heat-reducing foam tape provided by the present invention has good impact resistance, waterproof performance that can reach IPX8 level, and good anti-warping performance; in terms of viscosity, the peel strength of the pressure-sensitive adhesive layer for permanent bonding purposes can reach more than 30N / inch, and under high temperature conditions of 75°C, the peel strength decreases by no more than 10%; on the other hand, the controllable viscosity heat-reducing pressure-sensitive adhesive layer has the characteristic of controllable viscosity. Specifically, at room temperature, the peel strength can reach more than 20N / inch, at medium temperature, such as 55°C, the peel strength can reach more than 10N / inch, and at high temperature, such as 75°C*10min, the peel strength is controlled in the range of 1 to 3N / inch.

[0053] The above is the overall concept of the present invention, and detailed embodiments and comparative examples are provided below on the basis of the overall concept of the present invention to further illustrate the present invention.

[0054] Example 1

[0055] A viscous and heat-controllable anti-viscosity foam tape, the preparation method of which comprises the following steps:

[0056] S1. Preparation of pressure-sensitive adhesive layer for permanent bonding:

[0057] Use commercially available high-temperature resistant high-viscosity glue (product model: PS-8231, produced by Kunshan Shimei New Material Technology Co., Ltd.) and apply it on the release film by a doctor blade coating method, and dry it in an oven. The oven temperature is set to 110° C. and the drying time is 2 minutes to obtain a 50-micron-thick permanent bonding pressure-sensitive adhesive layer. The adhesive surface is bonded to the first surface of a 0.2-mm-thick black polyethylene foam substrate to obtain an intermediate product of a heat-reducing foam tape for standby use;

[0058] S2. Preparation of a viscous and heat-reducing pressure-sensitive adhesive layer:

[0059] S2-1. Preparation of high molecular polymer:

[0060] In a nitrogen atmosphere, 150 parts by weight of ethyl acetate, 65 parts by weight of soft monomer butyl acrylate, 20 parts by weight of hard monomer methyl acrylate, and 5 parts by weight of functional monomer acrylic acid were added to a four-mouth reactor and stirred at room temperature. 0.8 parts by weight of dibenzoyl peroxide was dissolved in 5 parts by weight of ethyl acetate and added to the four-mouth reactor under nitrogen atmosphere. The temperature was heated to 65° C. to initiate polymerization reaction. Stirring and temperature control were continued. After reacting for 7 hours, 0.5 parts by weight of dibenzoyl peroxide diluted with 5 parts by weight of ethyl acetate was added. The temperature was further raised to 85° C., and the reaction was continued for 2 hours. Then, 360 parts by weight of ethyl acetate was added to obtain a free radical polymerization acrylic polymer solution with a solid content of 40%. The free radical polymerization polymer was tested by gel permeation chromatography. The molecular weight of the free radical polymerization polymer was 700,000, and the molecular weight distribution was 3.89.

[0061] S2-2, take 100 parts by weight of the above-mentioned high molecular polymer, add 25 parts by weight of T-803L resin (Guangxi Wuzhou Arakawa Chemical Industry Co., Ltd.) with a solid content of 50% after being dissolved, 10 parts by weight of GA-90 resin (tackifying resin, rosin glycerol resin) (Guangxi Wuzhou Arakawa Chemical Industry Co., Ltd.) with a solid content of 50% after being dissolved, and then add 3 parts by weight of diluted L-75 resin (curing agent) (Covestro), stir evenly, dilute to a suitable viscosity with 20 parts by weight of ethyl acetate solvent, maintain high-speed dispersion for 20 minutes, and obtain a viscosity-controllable heat-reducing pressure-sensitive adhesive;

[0062] S2-3. Use a doctor blade coating method to apply a viscous controllable heat-reducing pressure-sensitive adhesive on the release film, and dry it in an oven. The oven temperature is set to 110°C and the drying time is 2 minutes to obtain a 50-micron-thick viscous controllable heat-reducing pressure-sensitive adhesive layer. The adhesive surface is bonded to the second surface of the foam substrate layer to obtain a viscous controllable heat-reducing foam tape.

[0063] Example 2

[0064] This example is basically the same as Example 1, and the main differences are listed below.

[0065] S2-2, take 100 parts by weight of the high molecular polymer in the above-mentioned Example 1, add 30 parts by weight of Dercolyte A125 resin (Kraton, USA) with a solid content of 50% after being dissolved, 5 parts by weight of Foral85 resin (Kraton, USA) with a solid content of 50% after being dissolved, and then add 4 parts by weight of diluted L-75 resin (Covestro), stir evenly, dilute to a suitable viscosity with 20 parts by weight of ethyl acetate solvent, maintain high-speed dispersion for 20 minutes, and obtain a viscosity-controllable heat-reducing pressure-sensitive adhesive;

[0066] S2-3. Use a doctor blade coating method to apply a viscous controllable heat-reducing pressure-sensitive adhesive on the release film, and dry it in an oven. The oven temperature is set to 110°C and the drying time is 2 minutes to obtain a 50-micron-thick viscous controllable heat-reducing pressure-sensitive adhesive layer. The adhesive surface is bonded to the second surface of the foam substrate layer to obtain a viscous controllable heat-reducing foam tape.

[0067] Example 3

[0068] This example is basically the same as Example 1, and the main differences are listed below.

[0069] S2-2, take 100g of the high molecular polymer in the above embodiment 1, add 25 parts by weight of Dertophene T135 resin (Kraton, USA) with a solid content of 50% after dissolution, 5 parts by weight of AS-5085F resin (Guangzhou Yabiao Technology Co., Ltd.) with a solid content of 50% after dissolution, and then add 3 parts by weight of diluted L-75 resin (Covestro), stir evenly, dilute to a suitable viscosity with 20 parts by weight of ethyl acetate solvent, maintain high-speed dispersion for 20 minutes, and obtain a viscosity-controllable heat-reducing pressure-sensitive adhesive;

[0070] S2-3. Use a doctor blade coating method to apply a viscous controllable heat-reducing pressure-sensitive adhesive on the release film, and dry it in an oven. The oven temperature is set to 110°C and the drying time is 2 minutes to obtain a 50-micron-thick viscous controllable heat-reducing pressure-sensitive adhesive layer. The adhesive surface is bonded to the second surface of the foam substrate layer to obtain a viscous controllable heat-reducing foam tape.

[0071] Comparative Example 1

[0072] This example is basically the same as Example 1, and the main differences are listed below.

[0073] S2-2, using 100 parts by weight of commercially available glue PS-8247 (produced by Kunshan Shimei New Materials Co., Ltd.), adding 3 parts by weight of diluted L-75 resin (Covestro), stirring evenly, using 20 parts by weight of ethyl acetate solvent to dilute to a suitable viscosity, maintaining high-speed dispersion for 20 minutes, and obtaining a pressure-sensitive adhesive;

[0074] S2-3. Use a doctor blade coating method to coat the pressure-sensitive adhesive prepared in step S2-2 on the release film, and dry it in an oven with the oven temperature set to 110°C and the drying time set to 2 minutes to obtain a 50-micron-thick, controllable-adhesive heat-reducing pressure-sensitive adhesive layer, and adhere the adhesive surface to the second surface of the foam substrate layer to obtain a controllable-adhesive heat-reducing foam tape.

[0075] Comparative Example 2

[0076] This example is basically the same as Example 1, and the main differences are listed below.

[0077] S2-2, take 100 parts by weight of the above-mentioned high molecular polymer, add 25 parts by weight of T-803L resin (Guangxi Wuzhou Arakawa Chemical Industry Co., Ltd.) with a solid content of 50% after dissolution, add 3 parts by weight of diluted L-75 resin (Covestro), stir evenly, dilute to a suitable viscosity with 20 parts by weight of ethyl acetate solvent, maintain high-speed dispersion for 20 minutes, and obtain a viscosity-controllable heat-reducing pressure-sensitive adhesive;

[0078] S2-3. Use a doctor blade coating method to apply a viscous controllable heat-reducing pressure-sensitive adhesive on the release film, and dry it in an oven. The oven temperature is set to 110°C and the drying time is 2 minutes to obtain a 50-micron-thick viscous controllable heat-reducing pressure-sensitive adhesive layer. The adhesive surface is bonded to the second surface of the foam substrate layer to obtain a viscous controllable heat-reducing foam tape.

[0079] Comparative Example 3

[0080] This example is basically the same as Example 1, and the main differences are listed below.

[0081] Take 100 parts by weight of the polymer in Example 1, add 25 parts by weight of GA-90 resin (Guangxi Wuzhou Arakawa Chemical Industry Co., Ltd.) with a solid content of 50% after dissolution, add 3 parts by weight of diluted L-75 resin (Covestro), stir evenly, dilute to a suitable viscosity with 20 parts by weight of ethyl acetate solvent, maintain high-speed dispersion for 20 minutes, and obtain a viscosity-controllable heat-reducing pressure-sensitive adhesive;

[0082] S2-3. Use a doctor blade coating method to apply a viscous controllable heat-reducing pressure-sensitive adhesive on the release film, and dry it in an oven. The oven temperature is set to 110°C and the drying time is 2 minutes to obtain a 50-micron-thick viscous controllable heat-reducing pressure-sensitive adhesive layer. The adhesive surface is bonded to the second surface of the foam substrate layer to obtain the viscous controllable heat-reducing foam tape.

[0083] The performance of the samples prepared in the above examples and comparative examples was evaluated using the following method.

[0084] 1. Test of molecular weight and molecular weight distribution

[0085] The obtained solution containing acrylic polymer was diluted 50 times with tetrahydrofuran, and the obtained dilution was filtered with a filter (polytetrafluoroethylene material, 0.2 μm pore size). The obtained filtrate was tested by gel permeation chromatography (Waters Company), wherein a GPC KF-806L (Showa Denko Co., Ltd.) chromatographic column was used and a differential refractometer was used as a detector. The test conditions were set to a flow rate of 1 ml / min and a column temperature of 40°C, and the polystyrene-equivalent molecular weight of the acrylic polymer was measured to obtain the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn).

[0086] 2. Anti-warping performance test

[0087] The double-sided tape with the heavy release film and the light release film layers removed was sandwiched between a 0.5 mm thick aluminum plate (180 mm × 25 mm) and a 2 mm thick PC plate (200 mm × 30 mm). The PC plate was bent into an arc shape. After 24 hours, the bounce distance of the aluminum plate with the adhesive tape was tested.

[0088] 3. Impact resistance test

[0089] The drop test uses PMMA (10cm×5cm×3mm) and aluminum plate (10cm×5cm×3mm) as substrates. Wipe the aluminum plate three times with isopropyl alcohol before the test. Two adhesive films with a length of 5cm, a width of 2mm, and a thickness of 200μm are parallel to the positions near the two ends of the PMMA plate, and the long side of the adhesive film is parallel to the short side of the PMMA plate. The drop test is tested using a directional drop tester. The test heights are 70cm, 120cm, and 190cm, respectively. First, place the test sample at the lowest height and record the number of drops at which the sample fails to bond. If the two bonded parts do not separate after falling from this height, it is considered that the bond is still valid. If the sample passes the drop test 30 times, it is raised to the next height and the drop test is continued, and the number of drops at which the sample fails to bond is recorded. Record the highest height and maximum number of times that the sample finally passes, and each test is repeated twice.

[0090] 4. Waterproof performance test

[0091] The tape sample is a U-shaped frame with an outer side length of 30 mm and an inner side length of 28 mm. The effective bonding area is 116 square millimeters. PC boards are bonded to both sides. A small amount of dry potassium permanganate powder is put into the U-shaped frame, 10 kg is pressed for 10 seconds, and placed in 1 meter deep water for 30 minutes. It is OK if the potassium permanganate does not change color.

[0092] 5. Peel force test

[0093] The measurement was carried out according to the ASTM D3330 method. The sample was cut into 25 mm width and 150 mm length. After being placed at 23°C and 50% RH for at least 2 hours, it was attached to a clean stainless steel plate or PP plastic plate, etc., and pressed back and forth once with a 2 kg pressing roller. The sample was peeled off using a peeling force measuring device (tensile testing machine, Shimadzu Corporation) at room temperature, a medium temperature of 55°C, or a high temperature of 75°C, a peeling angle of 180°, and a peeling speed of 300 mm / min. The 180° peeling force was tested, wherein the average value of N=3 was taken as the measured value.

[0094] 6. Test of holding power

[0095] The test was carried out according to the ASTM D3654 method. The sample was cut into 25mm width and 150mm length. After being placed at 23℃ and 50%RH for at least 2 hours, it was attached to the cleaned glass. A 2kg pressing roller was used to press back and forth once, keeping the attached area at 25mm*25mm. A 1kg weight was hung and the tape was kept in a 70℃ oven for 1 day to observe whether the tape was displaced or fell off.

[0096] The test results are shown in Table 1 below:

[0097] Table 1

[0098]

[0099]

[0100] According to the test results in Table 1, it can be seen that the adhesive tapes with controllable heat-reduced viscosity prepared in Examples 1-3 have good impact resistance, and the waterproof performance can reach the IPX8 level, and at the same time have good anti-warping performance; in terms of viscosity, the peel strength of the pressure-sensitive adhesive layer for permanent bonding purposes can reach more than 30N / inch, and under the condition of a high temperature of 75°C, the peel strength decreases by no more than 10%; on the other hand, the adhesive layer with controllable heat-reduced viscosity has the characteristic of controllable viscosity. Specifically, at room temperature, the peel strength can reach more than 20N / inch, at medium temperature, such as 55°C, the peel strength can reach more than 10N / inch, and at high temperature, such as 75°C*10min, the peel strength is controlled in the range of 1 to 3N / inch.

[0101] Through comparative analysis between the comparative examples and the embodiments, it can be seen that the controllable viscosity heat-reducing foam tape provided by the present invention has good comprehensive properties, for example, anti-warping performance, peel strength, holding power, waterproofness, impact resistance, etc., wherein, in terms of specific controllable viscosity performance, compared with the comparative example, the foam tape provided by the present invention has a lower peel force under high temperature conditions, in the range of 1 to 3 N / inch, and has a better detachable effect. Under normal temperature and medium temperature conditions, it has a peel strength of more than 10 N / inch, which can ensure that the bonding does not fail.

[0102] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A viscous and heat-controlled de-viscosity foam tape, characterized in that: include: A foam substrate layer, a permanent bonding pressure-sensitive adhesive layer located on a first surface of the foam substrate layer, and a controllable heat-reducing pressure-sensitive adhesive layer located on a second surface of the foam substrate layer; The controllable heat-reducing viscosity pressure-sensitive adhesive layer is obtained by coating a controllable heat-reducing viscosity pressure-sensitive adhesive and then curing it. The raw materials for preparing the controllable heat-reducing viscosity pressure-sensitive adhesive include, by weight: 100 parts of a high molecular polymer, 5 to 50 parts of a tackifying resin, 1.5 to 6 parts of a curing agent, and 20 to 50 parts of a first solvent.

2. The adhesive controllable heat-reducing foam tape according to claim 1, characterized in that: The high molecular polymer is obtained by polymerizing monomers under the action of an initiator. The raw materials for its preparation include, by weight: 30-130 parts of soft monomers, 10-40 parts of hard monomers, 2-10 parts of functional monomers, 80-320 parts of a second solvent, and 0.5-3 parts of an initiator.

3. The adhesive controllable heat-reducing foam tape according to claim 2, characterized in that: The soft monomer is one or more of ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and lauryl methacrylate; The hard monomer is one or more of acrylonitrile, vinyl acetate, acrylamide, styrene, methyl methacrylate, methyl acrylate, furfural-based monomer tetrahydrofurfuryl methacrylate, disproportionated rosin-modified monomer. The functional monomer is one or more of methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, acrylamide, N-hydroxymethyl acrylamide, glycidyl methacrylate, and maleic anhydride.

4. The adhesive controllable heat-reducing foam tape according to claim 2, characterized in that: The initiator is one or more of dibenzoyl peroxide, azobisisobutyronitrile, 2-methyl-2-n-butyltellurium-propionic acid, (methyltellurium-methyl)benzene, 1-chloro-4-(methyltellurium-methyl)benzene, 1-hydroxy-4-(methyltellurium-methyl)benzene, 1-phenoxycarboxyl-4-(2-methyltellurium-propyl)benzene, dimethyl ditellurium compounds, and diethyl ditellurium compounds; The second solvent is one or more of toluene, ethyl acetate and butanone.

5. The adhesive controllable heat-reducing foam tape according to claim 2, characterized in that: The high molecular weight polymer is prepared by the following method: In an atmosphere of nitrogen protection, the soft monomer, the hard monomer, the functional monomer and the second solvent are mixed, stirred evenly at room temperature, and then part of the initiator is added, the temperature is raised to 60-70°C, and the reaction is stirred for 4-10 hours; the remaining part of the initiator is added, the temperature is raised to 80-87°C, the reaction is carried out for 1-4 hours, and the second solvent is added for dilution to obtain the high molecular polymer.

6. The adhesive controllable heat-reducing foam tape according to claim 1, characterized in that: The tackifying resin is selected from one or more of rosin resin, modified rosin resin, terpene resin and its derivatives, phenolic resin, aliphatic petroleum resin, aromatic petroleum resin, and aliphatic and aromatic mixed petroleum resin.

7. The adhesive controllable heat-reducing foam tape according to claim 1, characterized in that: The curing agent is selected from one or more of isocyanates, epoxies, metal salts, and nitrogen pyridines; The first solvent is one or more of toluene, ethyl acetate and butanone.

8. The adhesive controllable heat-reducing foam tape according to claim 1, characterized in that: The raw materials for preparing the controllable-viscosity heat-reducing pressure-sensitive adhesive layer also include auxiliary agents, and the auxiliary agents are selected from one or more of color pastes, surfactants, antistatic agents, and coupling agents.

9. The adhesive controllable heat-reducing foam tape according to claim 1, characterized in that: The material of the foam substrate layer is one or more of polyethylene foam, acrylic foam, polypropylene foam, and polyurethane foam.

10. A method for preparing the adhesive controllable heat-reducing foam tape according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, applying glue on the release substrate to form a permanent adhesive pressure-sensitive adhesive layer after drying, and laminating the adhesive surface to the first surface of the foam substrate layer to obtain an intermediate product; S2. Coating a viscous and controllable heat-reducing pressure-sensitive adhesive on the release substrate to form a viscous and controllable heat-reducing pressure-sensitive adhesive layer after drying, and laminating the adhesive surface to the second surface of the foam substrate layer to obtain the viscous and controllable heat-reducing foam tape.

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