High-temperature-resistant water-based pressure-sensitive adhesive and preparation method thereof

Abstract

The invention relates to the technical field of pressure-sensitive adhesives, in particular to a high-temperature-resistant water-based pressure-sensitive adhesive and a preparation method thereof. A solvent type high-temperature-resistant pressure-sensitive adhesive is inflammable and volatile, is harmful to human bodies and seriously pollutes the environment. In order to solve the problems, the high-temperature-resistant water-based pressure-sensitive adhesive provided by the invention adopts a beta-acryloyloxypropionic acid-glycidyl methacrylate amphiphilic block polymer as an emulsifier of a pressure-sensitive adhesive latex system, and the emulsifier is a reactive polymer emulsifier. Epoxy groups of the emulsifier can be subjected to cross-linking reaction with carboxyl on an acrylate molecular chain in a latex system at high temperature, so that the problems of surface fogging, mist residue or'ghosting 'and the like caused by the fact that a traditional small-molecule emulsifier is easy to migrate to the surface of a material at high temperature can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a high temperature resistant water-based pressure-sensitive adhesive and a preparation method thereof. Background Art

[0002] As people pay more attention to environmental protection, safety and energy saving and the application of pressure-sensitive adhesives continues to expand, pressure-sensitive adhesives are driven to develop in the direction of low pollution, high performance and functionality.

[0003] The flexible circuit board assembly industry is the largest application market for high-temperature resistant double-sided pressure-sensitive adhesive tape in China. Before the reflow soldering process, the flexible circuit board needs to be mounted with double-sided pressure-sensitive adhesive on the surface of the flexible board for assembly or fixation in subsequent processes. This requires that the pressure-sensitive adhesive used can withstand a short-term high-temperature environment without performance degradation. With the popularization of lead-free reflow soldering technology in the flexible board industry, higher requirements are placed on the temperature resistance of pressure-sensitive adhesive tape.

[0004] At present, high temperature resistant double-sided pressure sensitive adhesive tapes mostly use solvent-based pressure sensitive adhesives. Solvent-based pressure sensitive adhesives usually use small molecule emulsifiers to emulsify and disperse their material systems. Commonly used small molecule emulsifiers are anionic emulsifiers sodium dodecyl sulfate or non-ionic emulsifiers polyoxyethylene octylphenol ether. The presence of small molecule emulsifiers causes solvent-based pressure sensitive adhesives to cause fogging, fog residue, "ghosting" and other problems on the surface of the protected material at high temperatures. Summary of the invention

[0005] The problems existing in the prior art are: solvent-based high temperature resistant pressure sensitive adhesives are flammable, volatile, harmful to the human body, and cause serious environmental pollution. In view of the above problems, the present invention provides a high temperature resistant water-based pressure sensitive adhesive, which comprises the following raw materials in parts by weight:

[0006]

[0007] The polymer amphiphilic emulsifier is a β-acryloxypropionic acid-glycidyl methacrylate amphiphilic block polymer, and the preparation method of the polymer amphiphilic emulsifier comprises the following steps:

[0008] Under nitrogen protection, 60g of β-carboxyethyl acrylate, 80g of butanone, 2g of 4-cyano-4-[[(dodecylthio)thiocarbonyl]thio]pentanoic acid, and 0.8g of azobisisobutyronitrile are added to a reactor, and the mixture is stirred at a constant temperature of 60°C for 12-24h. Then, AMP-95 is added to the reaction system for neutralization reaction, so that the pH of the reaction system is 7-8. Then, 20g of glycidyl methacrylate and 2.2g of azobisisobutyronitrile are added to the reaction system, and the mixture is stirred at a constant temperature of 60°C for 12-24h. Finally, the solvent is removed by vacuum at 65°C to obtain a β-acryloxypropionic acid-glycidyl methacrylate amphiphilic block polymer, i.e., a reactive polymer amphiphilic emulsifier;

[0009] The tetrafunctional modified epoxy resin contains a double bond and three epoxy groups in its molecular structure.

[0010] Preferably, the preparation method of the tetrafunctional modified epoxy resin comprises the following steps:

[0011] (1) 4,4'-diphenylsulfone diamine and excess epichlorohydrin are added to anhydrous ethanol, and the mixture is stirred at a constant temperature of 30-50°C to react. The reaction is monitored by FTIR. When the absorption peak of the amino group disappears in the infrared spectrum, the reaction is completed. After the reaction is completed, the excess epichlorohydrin is removed by vacuum distillation to obtain an intermediate product I. The chemical structure of the intermediate product I is as follows:

[0012]

[0013] (2) Then, alkali is added dropwise to the above reaction system while stirring, and the reaction is stirred at a constant temperature of 35-70° C., and the progress of the reaction is monitored by FTIR. When the absorption peak of the epoxy group in the infrared spectrum no longer increases, the addition of alkali is stopped and the reaction is terminated. Then, methyl isobutyl ketone and deionized water are added to the reaction system of step (2), and after stirring evenly, liquid separation and extraction are performed to remove the water layer, and a sodium hydroxide aqueous solution with a mass concentration of 10-15% is added to the remaining extract, and the volume ratio of the sodium hydroxide aqueous solution to the remaining extract is 1:2. Then, the reaction is stirred at a constant temperature of 50-65° C. for 1-3 hours, and then the reaction solution is washed with a sodium chloride aqueous solution until it is neutral, and the solvent is removed by reduced pressure distillation to obtain a tetrafunctional epoxy resin. The chemical structure of the tetrafunctional epoxy resin is as follows:

[0014]

[0015] (3) A tetrafunctional epoxy resin is placed in a reactor and heated to 50° C., and then acrylic acid is added dropwise to the reactor at 50° C. while stirring. The reaction is monitored by FTIR. When the epoxy groups in the reaction system are reduced to 3 / 4 of the original, the addition of acrylic acid is stopped. Then, the temperature of the reaction system is raised to 60° C. and stirred at a constant temperature for 5 hours. After the reaction is completed, a tetrafunctional modified epoxy resin is obtained. The structural formula of the tetrafunctional modified epoxy resin is as follows:

[0016]

[0017] Preferably, the alkali in step (2) is an aqueous NaOH solution or an aqueous KOH solution with a mass concentration of 15-40%.

[0018] Preferably, the mass concentration of the sodium chloride aqueous solution is 2-8%.

[0019] Preferably, the acrylic acid ester monomer includes one or more of butyl acrylate, isooctyl acrylate, and methyl methacrylate.

[0020] Preferably, the cross-linking monomer includes at least one of ethyl acetoacetoxymethacrylate and diacetone acrylamide.

[0021] Preferably, the initiator comprises potassium persulfate or ammonium persulfate.

[0022] Preferably, the reducing agent is a sodium sulfinate derivative.

[0023] Preferably, the preparation method of the high temperature resistant water-based pressure-sensitive adhesive comprises the following steps:

[0024] (1) After fully mixing the tetrafunctional modified epoxy resin, acrylate monomer, acrylic acid, and crosslinking monomer according to the formula amount, the mixture is then mixed with 13 / 25 formula amount of deionized water, 3 / 5 formula amount of initiator, and polymer amphiphilic emulsifier, and the monomer pre-emulsion is obtained by high-speed stirring and emulsification;

[0025] (2) heating the remaining amount of deionized water to 80° C., adding 5-8% of the total mass of the monomer pre-emulsion obtained in step (1) and all the remaining initiators, and reacting with constant temperature stirring for 20-30 minutes, then dropping all the remaining monomer pre-emulsion within 4 hours, stirring at constant temperature for 1 hour, and then reducing the temperature of the reaction system to 60-65° C., and starting to drop the formula amount of reducing agent into the reaction system while stirring, and the dropping time is controlled within 30-45 minutes. After the dropwise addition is completed, stirring and reacting at constant temperature for 0.5 hours, and then raising the temperature of the reaction system to 80° C., stirring at constant temperature for 1 hour, and then reducing the temperature of the reaction system to below 45° C., adding the formula amount of pH regulator so that the pH of the reaction system is 7-8, and then adding the formula amount of curing agent into the reaction system, stirring evenly, filtering and discharging the material, and thus obtaining a high temperature resistant water-based pressure-sensitive adhesive.

[0026] Preferably, the pH adjuster is aqueous ammonia.

[0027] The present invention has the following beneficial effects:

[0028] (1) The self-made tetrafunctional modified epoxy resin of the present invention contains one vinyl group and three epoxy groups, has a high crosslinking density after curing, and has excellent high temperature resistance. The double bonds of the vinyl group and the acrylic acid monomer are chemically bonded to copolymerize and graft the molecular structure onto the main chain of the acrylate. The introduced epoxy group can react with the carboxyl group on the acrylate molecular chain at high temperature to crosslink, and can also react with adipic acid dihydrazide to undergo external crosslinking and curing to form an IPN-like structure. The epoxy resin with high crosslinking density plays a role of skeleton support in the system, can provide good cohesive strength for the pressure-sensitive adhesive at high temperature, can greatly improve the high temperature resistance of the acrylate pressure-sensitive adhesive, and is not prone to residual adhesive.

[0029] (2) The polymer amphiphilic emulsifier obtained by the present invention is a β-carboxyethyl acrylate-glycidyl methacrylate amphiphilic block polymer, which can effectively emulsify the polymerization monomers to carry out continuous saponification-free emulsion polymerization. The surface energy of the obtained water-based acrylic pressure-sensitive adhesive layer is lower, and it has better wettability and air-degassing performance. The obtained water-based acrylic pressure-sensitive adhesive layer has a low peeling force increase under high temperature and high humidity, and is not prone to residual adhesive at high temperature;

[0030] (3) The high-temperature water-based pressure-sensitive adhesive material system obtained by the present invention further contains a latent curing agent, adipic acid dihydrazide, which does not react with epoxy groups at room temperature. At high temperatures, the epoxy groups on the acrylate molecular chain and adipic acid dihydrazide undergo external crosslinking and curing. The crosslinking characteristics of the latent curing agent adipic acid dihydrazide have the following advantages: the pressure-sensitive adhesive has a low degree of crosslinking at room temperature, has good initial adhesion and high peel strength, and has a higher degree of crosslinking at high temperatures, and is less likely to have residual adhesive.

[0031] (4) The polymer amphiphilic emulsifier developed for the pressure-sensitive adhesive material system of the present invention is a reactive polymer emulsifier with a moderate molecular weight. It uses β-acryloxypropionic acid and glycidyl methacrylate as block copolymer monomers. Compared with other monomers, such as acrylic acid, methacrylic acid, butyl acrylate or isooctyl acrylate, it has better compatibility with the epoxy-containing acrylic ester molecular chain in the latex system. The water-based acrylic ester pressure-sensitive adhesive latex system prepared by the emulsifier has better dispersibility and stability. The obtained pressure-sensitive adhesive can form a more uniform pressure-sensitive adhesive layer on the surface of the substrate. At high temperature, the epoxy group reacts with adipic acid dihydrazide and with the carboxyl group on the acrylic ester molecular chain to further reduce the occurrence of residual adhesive.

[0032] (5) The polymer amphiphilic emulsifier obtained by the present invention is a reactive emulsifier, and its epoxy group can undergo a cross-linking reaction with the carboxyl group on the acrylate molecular chain in the latex system at high temperature, which can effectively solve the problems of traditional small molecule emulsifiers easily migrating to the surface of the material at high temperature, resulting in surface fogging, foggy residue or "ghosting". DETAILED DESCRIPTION

[0033] The present invention is described in detail below with reference to the examples. However, it should be understood that the following examples are only illustrative of the embodiments of the present invention, and are not intended to limit the scope of the present invention.

[0034] The polymer amphiphilic emulsifier in the following embodiments of the present invention is a β-acryloxypropionic acid-glycidyl methacrylate amphiphilic block polymer, and the preparation method of the polymer amphiphilic emulsifier is as follows:

[0035] Under nitrogen protection, 60g of β-carboxyethyl acrylate, 80g of butanone, 2g of 4-cyano-4-[[(dodecylthio)thiocarbonyl]thio]pentanoic acid (CAS: 870196-80-8) and 0.8g of azobisisobutyronitrile were added to the reactor, and the mixture was stirred at a constant temperature of 60°C for 12-24h. Then, AMP-95 was added to the reaction system for neutralization reaction so that the pH of the reaction system was 7-8. Then, 20g of glycidyl methacrylate and 2.2g of azobisisobutyronitrile were added to the reaction system, and the mixture was stirred at a constant temperature of 60°C for 12-24h. Finally, the solvent was removed by vacuum at 65°C to obtain a β-acryloxypropionic acid-glycidyl methacrylate amphiphilic block polymer, i.e., a reactive polymer amphiphilic emulsifier.

[0036] The preparation method of the tetrafunctional modified epoxy resin in the following embodiments of the present invention is as follows:

[0037] (1) 4,4'-diphenylsulfone diamine and excess epichlorohydrin are added to anhydrous ethanol, and the mixture is stirred at a constant temperature of 30-50°C to react. The reaction is monitored by FTIR. When the absorption peak of the amino group disappears in the infrared spectrum, the reaction is completed. After the reaction is completed, the excess epichlorohydrin is removed by vacuum distillation to obtain an intermediate product I. The chemical structure of the intermediate product I is as follows:

[0038]

[0039] (2) Then, alkali is added dropwise to the above reaction system while stirring, and the reaction is stirred at a constant temperature of 35-70° C., and the reaction is monitored by FTIR. When the absorption peak of the epoxy group in the infrared spectrum no longer increases, the addition of alkali is stopped and the reaction is terminated. Then, methyl isobutyl ketone and deionized water are added to the reaction system of step (2), and after stirring evenly, liquid separation and extraction are performed to remove the water layer, and a sodium hydroxide aqueous solution with a mass concentration of 10-15% is added to the remaining extract, and the volume ratio of the sodium hydroxide aqueous solution to the remaining extract is 1:2. Then, the reaction is stirred at a constant temperature of 50-65° C. for 1-3 hours, and then the reaction solution is washed with a sodium chloride aqueous solution until it is neutral, and the solvent is removed by reduced pressure distillation to obtain a tetrafunctional epoxy resin. The alkali is a NaOH aqueous solution with a mass concentration of 40%, and the mass concentration of the sodium chloride aqueous solution is 2-8%. The chemical structure of the tetrafunctional epoxy resin is as follows:

[0040]

[0041] (3) A tetrafunctional epoxy resin is placed in a reactor and heated to 50° C., and then acrylic acid is added dropwise to the reactor at 50° C. while stirring. The reaction is monitored by FTIR. When the epoxy groups in the reaction system are reduced to 3 / 4 of the original, the addition of acrylic acid is stopped. Then, the temperature of the reaction system is raised to 60° C. and stirred at a constant temperature for 5 hours. After the reaction is completed, a tetrafunctional modified epoxy resin is obtained. The structural formula of the tetrafunctional modified epoxy resin is as follows:

[0042]

[0043] Example 1

[0044] A high temperature resistant water-based pressure-sensitive adhesive, which has the following raw material composition in parts by weight:

[0045]

[0046] The acrylic acid ester monomer is composed of butyl acrylate, isooctyl acrylate and methyl methacrylate in a mass ratio of 200:60:45.

[0047] The cross-linking monomer is composed of ethyl acetoacetate methacrylate and diacetone acrylamide in a mass ratio of 1:1.

[0048] The initiator is potassium persulfate.

[0049] The reducing agent is Bruggolite FF6M, purchased from Bruggolite of Germany.

[0050] The high temperature resistant water-based pressure-sensitive adhesive is prepared as follows:

[0051] (1) After fully mixing the tetrafunctional modified epoxy resin, acrylate monomer, acrylic acid, and crosslinking monomer according to the formula amount, the mixture is then mixed with 13 / 25 formula amount of deionized water, 3 / 5 formula amount of initiator, and polymer amphiphilic emulsifier, and the monomer pre-emulsion is obtained by high-speed stirring and emulsification;

[0052] (2) The remaining amount of deionized water is heated to 80°C, 5% of the total mass of the monomer pre-emulsion obtained in step (1) and the remaining initiator are added, and the reaction is stirred at a constant temperature for 20 minutes. Then, the remaining amount of monomer pre-emulsion is added dropwise within 4 hours, and the reaction is stirred at a constant temperature for 1 hour. Then, the temperature of the reaction system is reduced to 60°C, and the reducing agent is added dropwise to the reaction system while stirring. The dropping time is controlled within 30 minutes. After the dropwise addition is completed, the reaction is stirred at a constant temperature for 0.5 hours. Then, the temperature of the reaction system is raised to 80°C, and the reaction is stirred at a constant temperature for 1 hour. Then, the temperature of the reaction system is reduced to below 45°C, and the pH value regulator is added to make the pH of the reaction system = 7. Then, the curing agent is added to the reaction system, and after stirring, the material is filtered to obtain a high temperature resistant water-based pressure-sensitive adhesive. The pH value regulator is ammonia water.

[0053] Example 2

[0054] A high temperature resistant water-based pressure-sensitive adhesive, which has the following raw material composition in parts by weight:

[0055]

[0056] The acrylic acid ester monomer is composed of butyl acrylate, isooctyl acrylate and methyl methacrylate in a mass ratio of 200:60:45.

[0057] The cross-linking monomer is composed of ethyl acetoacetate methacrylate and diacetone acrylamide in a mass ratio of 1:1.

[0058] The initiator is ammonium persulfate.

[0059] The reducing agent is Bruggolite FF6M, purchased from Bruggolite of Germany.

[0060] The high temperature resistant water-based pressure-sensitive adhesive is prepared as follows:

[0061] (1) After fully mixing the tetrafunctional modified epoxy resin, acrylate monomer, acrylic acid, and crosslinking monomer according to the formula amount, the mixture is then mixed with 13 / 25 formula amount of deionized water, 3 / 5 formula amount of initiator, and polymer amphiphilic emulsifier, and the monomer pre-emulsion is obtained by high-speed stirring and emulsification;

[0062] (2) The remaining amount of deionized water is heated to 80° C., 8% of the total mass of the monomer pre-emulsion obtained in step (1) and all the remaining initiators are added, and the mixture is stirred at a constant temperature for 30 min. Then, the remaining amount of monomer pre-emulsion is added dropwise within 4 h, and the mixture is stirred at a constant temperature for 1 h. Then, the temperature of the reaction system is reduced to 65° C., and the reducing agent is added dropwise to the reaction system while stirring. The addition time is controlled within 45 min. After the addition is completed, the mixture is stirred at a constant temperature for 0.5 h. Then, the temperature of the reaction system is raised to 80° C., and the mixture is stirred at a constant temperature for 1 h. Then, the temperature of the reaction system is reduced to below 45° C., a pH regulator is added to adjust the pH of the reaction system to 7, and then a curing agent is added to the reaction system. After stirring, the mixture is filtered to obtain a high temperature resistant water-based pressure-sensitive adhesive.

[0063] The pH adjuster is ammonia water.

[0064] Example 3

[0065] A high temperature resistant water-based pressure-sensitive adhesive, which has the following raw material composition in parts by weight:

[0066]

[0067]

[0068] The acrylic acid ester monomer is composed of butyl acrylate, isooctyl acrylate and methyl methacrylate in a mass ratio of 200:60:45.

[0069] The cross-linking monomer is composed of ethyl acetoacetate methacrylate and diacetone acrylamide in a mass ratio of 1:1.

[0070] The initiator is potassium persulfate.

[0071] The reducing agent is Bruggolite FF6M, purchased from Bruggolite of Germany.

[0072] The high temperature resistant water-based pressure-sensitive adhesive is prepared as follows:

[0073] (1) After fully mixing the tetrafunctional modified epoxy resin, acrylate monomer, acrylic acid, and crosslinking monomer according to the formula amount, the mixture is mixed with 13 / 25 formula amount of deionized water, 3 / 5 formula amount of initiator, and polymer amphiphilic emulsifier, and the monomer pre-emulsion is obtained by high-speed stirring and pressurized emulsification;

[0074] (2) The remaining amount of deionized water is heated to 80°C, 6% of the total mass of the monomer pre-emulsion obtained in step (1) and the remaining initiator are added, and the reaction is stirred at a constant temperature for 25 minutes. Then, the remaining amount of monomer pre-emulsion is added dropwise within 4 hours, and the reaction is stirred at a constant temperature for 1 hour. Then, the temperature of the reaction system is reduced to 62°C, and the reducing agent is added dropwise to the reaction system while stirring. The dropping time is controlled within 35 minutes. After the dropwise addition is completed, the reaction is stirred at a constant temperature for 0.5 hours. Then, the temperature of the reaction system is raised to 80°C, and the reaction is stirred at a constant temperature for 1 hour. Then, the temperature of the reaction system is reduced to below 45°C, and the pH value regulator is added to make the pH of the reaction system = 7. Then, the curing agent is added to the reaction system, and after stirring, the material is filtered to obtain a high temperature resistant water-based pressure-sensitive adhesive. The pH value regulator is ammonia water.

[0075] Comparative Example 1 is the same as Example 1, except that the emulsifier in Comparative Example 1 is an acrylic acid-methacrylic acid glycidyl ester amphiphilic block polymer, and the preparation method of the emulsifier is as follows: 60g acrylic acid, 80g butanone, 2g 4-cyano-4-[[(dodecylthio)thiocarbonyl]thio]pentanoic acid, and 0.8g azobisisobutyronitrile are added to a reactor, and the mixture is stirred at a constant temperature of 60°C for 12-24h, and then AMP-95 is added to the reaction system for neutralization reaction so that the pH of the reaction system is 7, and then 20g glycidyl methacrylate and 2.2g azobisisobutyronitrile are added to the reaction system, and the mixture is stirred at a constant temperature of 60°C for 12-24h, and finally the solvent is removed by vacuum at 65°C to obtain an acrylic acid-methacrylic acid glycidyl ester amphiphilic block polymer, i.e., a reactive polymer amphiphilic emulsifier;

[0076] Comparative Example 2 is the same as Example 1, except that the emulsifier in Comparative Example 2 is a methacrylic acid-glycidyl methacrylate amphiphilic block polymer, and the preparation method of the emulsifier is as follows: 60g of methacrylic acid, 80g of butanone, 2g of 4-cyano-4-[[(dodecylthio)thiocarbonyl]thio]pentanoic acid, and 0.8g of azobisisobutyronitrile are added to a reactor, and stirred at a constant temperature of 60°C for reaction for 12-24h, and then AMP-95 is added to the reaction system for neutralization reaction so that the pH of the reaction system is 7, and then 20g of glycidyl methacrylate and 2.2g of azobisisobutyronitrile are added to the reaction system, and then stirred at a constant temperature of 60°C for reaction for 12-24h, and finally the solvent is removed by vacuum at 65°C to obtain a methacrylic acid-glycidyl methacrylate amphiphilic block polymer, that is, a reactive polymer amphiphilic emulsifier;

[0077] Comparative Example 3 is the same as Example 1, except that the emulsifier in Comparative Example 3 is a β-acryloxypropionic acid-butyl acrylate amphiphilic block polymer, and the preparation method of the emulsifier is as follows: 60g β-carboxyethyl acrylate, 80g ethanol, 2g 4-cyano-4-[[(dodecylthio)thiocarbonyl]thio]pentanoic acid (CAS: 870196-80-8), and 0.8g azobisisobutyronitrile are added to a reactor, stirred at a constant temperature of 60°C for 12h, and then 20g butyl acrylate and 2.2g azobisisobutyronitrile are added to the reaction system, and then stirred at a constant temperature of 60°C for 12h, and then AMP-95 is added to the reaction system for neutralization reaction, so that the pH of the reaction system is 7, and finally the solvent is removed by vacuum at 65°C to obtain a β-carboxyethyl acrylate-butyl acrylate amphiphilic block polymer, that is, a polymer amphiphilic emulsifier.

[0078] Comparative Example 4 is the same as Example 1, except that the emulsifier in Comparative Example 4 is a β-acryloxypropionic acid-isooctyl acrylate amphiphilic block polymer, and the preparation method of the emulsifier is as follows: 60g of β-carboxyethyl acrylate, 80g of ethanol, 2g of 4-cyano-4-[[(dodecylthio)thiocarbonyl]thio]pentanoic acid, and 0.8g of azobisisobutyronitrile are added to a reactor, stirred at a constant temperature of 60°C for 12h, and then 20g of isooctyl acrylate and 2.2g of azobisisobutyronitrile are added to the reaction system, and then stirred at a constant temperature of 60°C for 12h, and then AMP-95 is added to the reaction system for neutralization reaction so that the pH of the reaction system is 7, and finally the solvent is removed by vacuum at 65°C to obtain a β-carboxyethyl acrylate-isooctyl acrylate amphiphilic block polymer, that is, a polymer amphiphilic emulsifier.

[0079] Comparative Example 5 is the same as Example 1, except that the preparation method of the tetrafunctional modified epoxy resin in Comparative Example 5 is as follows:

[0080] (1) 4,4'-diphenylsulfone diamine and excess epichlorohydrin are added to anhydrous ethanol, and the mixture is stirred at a constant temperature of 30-50°C to react. The reaction is monitored by FTIR. When the absorption peak of the amino group disappears in the infrared spectrum, the reaction is completed. After the reaction is completed, the excess epichlorohydrin is removed by vacuum distillation to obtain an intermediate product I. The chemical structure of the intermediate product I is as follows:

[0081]

[0082] (2) Then, alkali is added dropwise to the above reaction system while stirring, and the reaction is stirred at a constant temperature of 35-70° C., and the reaction is monitored by FTIR. When the absorption peak of the epoxy group in the infrared spectrum no longer increases, the addition of alkali is stopped and the reaction is terminated. Then, methyl isobutyl ketone and deionized water are added to the reaction system of step (2), and after stirring evenly, liquid separation and extraction are performed to remove the water layer, and a sodium hydroxide aqueous solution with a mass concentration of 10-15% is added to the remaining extract, and the volume ratio of the sodium hydroxide aqueous solution to the remaining extract is 1:2. Then, the reaction is stirred at a constant temperature of 50-65° C. for 1-3 hours, and then the reaction solution is washed with a sodium chloride aqueous solution until it is neutral, and the solvent is removed by reduced pressure distillation to obtain a tetrafunctional epoxy resin. The alkali is a NaOH aqueous solution with a mass concentration of 40%, and the mass concentration of the sodium chloride aqueous solution is 2-8%. The chemical structure of the tetrafunctional epoxy resin is as follows:

[0083]

[0084] (3) A tetrafunctional epoxy resin is placed in a reactor and heated to 50°C. Then, acrylic acid is added dropwise to the reactor at 50°C while stirring. The reaction is monitored by FTIR. When the epoxy groups in the reaction system are reduced to 1 / 2 of the original amount, the addition of acrylic acid is stopped. Then, the temperature of the reaction system is raised to 60°C and stirred at a constant temperature for 5 hours. After the reaction is completed, a tetrafunctional modified epoxy resin is obtained. The obtained tetrafunctional modified epoxy resin contains two double bonds and two epoxy groups.

[0085] Comparative Example 6 is the same as Example 1, except that the tetrafunctional modified epoxy resin in Example 1 is replaced by the same weight portion of E51 epoxy resin in Comparative Example 6.

[0086] Comparative Example 7 is the same as Example 1, except that the polymer amphiphilic emulsifier in Example 1 is replaced by sodium dodecyl sulfate in equal parts by weight as an emulsifier.

[0087] Comparative Example 8 is the same as Example 1, except that Comparative Example 8 uses an equal weight portion of nonionic emulsifier polyoxyethylene octylphenol ether as an emulsifier to replace the high molecular weight amphiphilic emulsifier in Example 1.

[0088] Comparative Example 9 is the same as Example 1, except that the tetrafunctional epoxy resin obtained in Example 1 is used in Comparative Example 9 to replace the tetrafunctional modified epoxy resin in Example 1. The chemical structure of the tetrafunctional epoxy resin in Comparative Example 9 is as follows:

[0089]

[0090] Performance Testing

[0091] The pressure-sensitive adhesives obtained in Examples 1-3 of the present invention and Comparative Examples 1-9 were respectively subjected to relevant performance tests, and the specific test results are shown in Table 1.

[0092] Sample preparation method: The pressure-sensitive adhesive is coated on a 40 μm thick polyimide film and cured at 120°C for 2 minutes to obtain a pressure-sensitive adhesive tape sample with a thickness of 20 μm.

[0093] Then the pressure-sensitive adhesive tape samples were tested for initial adhesion, sustained adhesion, 180° peel strength and high temperature resistance.

[0094] Loop initial tack: Determined in accordance with "Test method for initial tack of pressure-sensitive adhesive tapes (loop method)" GB / T31125-2014;

[0095] 180° peel strength: measured in accordance with "Test method for peel strength of adhesive tape" GB / T 2792-2014;

[0096] Adhesion: Determined according to "Adhesion Test Method for Adhesive Tapes" GB / T 4851-2014;

[0097] Residual adhesive: The test is carried out according to the standard made by the enterprise, that is, a 25mm wide tape is pasted on a standard stainless steel plate and placed at 220℃ for 1h. It is required that there is no residual adhesive when hot peeling or room temperature peeling.

[0098] Table 1

[0099]

[0100] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A high temperature resistant water-based pressure-sensitive adhesive, characterized in that: The composition is composed of the following raw materials in parts by weight: The polymer amphiphilic emulsifier is a β-acryloxypropionic acid-glycidyl methacrylate amphiphilic block polymer, and the preparation method of the polymer amphiphilic emulsifier comprises the following steps: Under nitrogen protection, 60g of β-carboxyethyl acrylate, 80g of butanone, 2g of 4-cyano-4-[[(dodecylthio)thiocarbonyl]thio]pentanoic acid, and 0.8g of azobisisobutyronitrile are added to a reactor, and the mixture is stirred at a constant temperature of 60°C for 12-24h. Then, AMP-95 is added to the reaction system for neutralization reaction, so that the pH of the reaction system is 7-8. Then, 20g of glycidyl methacrylate and 2.2g of azobisisobutyronitrile are added to the reaction system, and the mixture is stirred at a constant temperature of 60°C for 12-24h. Finally, the solvent is removed by vacuum at 65°C to obtain a β-acryloxypropionic acid-glycidyl methacrylate amphiphilic block polymer, i.e., a reactive polymer amphiphilic emulsifier; The tetrafunctional modified epoxy resin contains a double bond and three epoxy groups in its molecular structure.

2. A high temperature resistant water-based pressure-sensitive adhesive according to claim 1, characterized in that: The preparation method of the tetrafunctional modified epoxy resin comprises the following steps: (1) 4,4'-diphenylsulfone diamine and excess epichlorohydrin are added to anhydrous ethanol, and the mixture is stirred at a constant temperature of 30-50°C to react. The reaction is monitored by FTIR. When the absorption peak of the amino group disappears in the infrared spectrum, the reaction is completed. After the reaction is completed, the excess epichlorohydrin is removed by vacuum distillation to obtain an intermediate product I. The chemical structure of the intermediate product I is as follows: (2) Then, alkali is added dropwise to the above reaction system while stirring, and the reaction is stirred at a constant temperature of 35-70° C., and the progress of the reaction is monitored by FTIR. When the absorption peak of the epoxy group in the infrared spectrum no longer increases, the addition of alkali is stopped and the reaction is terminated. Then, methyl isobutyl ketone and deionized water are added to the reaction system of step (2), and after stirring evenly, liquid separation and extraction are performed to remove the water layer, and a sodium hydroxide aqueous solution with a mass concentration of 10-15% is added to the remaining extract, and the volume ratio of the sodium hydroxide aqueous solution to the remaining extract is 1:

2. Then, the reaction is stirred at a constant temperature of 50-65° C. for 1-3 hours, and then the reaction solution is washed with a sodium chloride aqueous solution until it is neutral, and the solvent is removed by reduced pressure distillation to obtain a tetrafunctional epoxy resin. The chemical structure of the tetrafunctional epoxy resin is as follows: (3) A tetrafunctional epoxy resin is placed in a reactor and heated to 50° C., and then acrylic acid is added dropwise to the reactor at 50° C. while stirring. The reaction is monitored by FTIR. When the epoxy groups in the reaction system are reduced to 3 / 4 of the original, the addition of acrylic acid is stopped. Then, the temperature of the reaction system is raised to 60° C. and stirred at a constant temperature for 5 hours. After the reaction is completed, a tetrafunctional modified epoxy resin is obtained. The structural formula of the tetrafunctional modified epoxy resin is as follows:

3. A high temperature resistant water-based pressure-sensitive adhesive according to claim 2, characterized in that: The alkali in step (2) is a NaOH aqueous solution or a KOH aqueous solution with a mass concentration of 15-40%.

4. The high temperature resistant water-based pressure-sensitive adhesive according to claim 2, characterized in that: The mass concentration of the sodium chloride aqueous solution is 2-8%.

5. The high temperature resistant water-based pressure-sensitive adhesive according to claim 1, characterized in that: The acrylic acid ester monomer includes one or more of butyl acrylate, isooctyl acrylate and methyl methacrylate.

6. The high temperature resistant water-based pressure sensitive adhesive according to claim 1, characterized in that: The cross-linking monomer includes at least one of ethyl acetoacetate and adipic acid dihydrazide.

7. The high temperature resistant water-based pressure sensitive adhesive according to claim 1, characterized in that: The initiator includes potassium persulfate or ammonium persulfate.

8. The high temperature resistant water-based pressure-sensitive adhesive according to claim 1, characterized in that: The reducing agent is a sodium sulfinate derivative.

9. A high temperature resistant water-based pressure sensitive adhesive according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: (1) After fully mixing the tetrafunctional modified epoxy resin, acrylate monomer, acrylic acid, and crosslinking monomer according to the formula amount, the mixture is then mixed with 13 / 25 formula amount of deionized water, 3 / 5 formula amount of initiator, and polymer amphiphilic emulsifier, and the monomer pre-emulsion is obtained by high-speed stirring and emulsification; (2) heating the remaining amount of deionized water to 80° C., adding 5-8% of the total mass of the monomer pre-emulsion obtained in step (1) and all the remaining initiators, and reacting with constant temperature stirring for 20-30 minutes, then dropping all the remaining monomer pre-emulsion within 4 hours, stirring at constant temperature for 1 hour, and then reducing the temperature of the reaction system to 60-65° C., and starting to drop the formula amount of reducing agent into the reaction system while stirring, and the dropping time is controlled within 30-45 minutes. After the dropwise addition is completed, stirring and reacting at constant temperature for 0.5 hours, and then raising the temperature of the reaction system to 80° C., stirring at constant temperature for 1 hour, and then reducing the temperature of the reaction system to below 45° C., adding the formula amount of pH regulator so that the pH of the reaction system is 7-8, and then adding the formula amount of curing agent into the reaction system, stirring evenly, filtering and discharging the material, and thus obtaining a high temperature resistant water-based pressure-sensitive adhesive.

10. The high temperature resistant water-based pressure-sensitive adhesive according to claim 9, characterized in that: The pH adjuster is ammonia water.

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