Photolysis pressure-sensitive adhesive emulsion, preparation method thereof and water-based cationic photolysis pressure-sensitive adhesive

Abstract

The invention discloses a photo-debonding pressure-sensitive adhesive emulsion, a preparation method thereof and a water-based cationic photo-debonding pressure-sensitive adhesive. The reaction raw materials of the water-based photodebonding pressure-sensitive adhesive emulsion comprise the emulsifier, the water, the soft monomer, the hard monomer, the functional monomer and the modified monomer, and by selecting the special emulsifier, the functional monomer and the modified monomer, the prepared emulsion is higher in stability, can effectively stabilize latex particles, and has good stability. The water whitening resistance, the chemical resistance and the mechanical stability of the emulsion are improved. The emulsion can be applied to the photolysis pressure-sensitive adhesive, and under ultraviolet irradiation, the photolysis pressure-sensitive adhesive can quickly form a film without residual adhesive, and the adhesive strength is obviously reduced along with time. The photo-debonding pressure-sensitive adhesive prepared by the invention has the characteristics of high initial adhesion, high viscosity, fast debonding and excellent water resistance, and also has the advantages of safety, low toxicity, odorlessness, easiness in operation and the like.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, and in particular to a photodegradable pressure-sensitive adhesive latex and a preparation method thereof, and an aqueous cationic photodegradable pressure-sensitive adhesive. Background Art

[0002] Photodebonding pressure-sensitive adhesive is an emerging adhesive material. It has good bonding properties at the beginning, but can be quickly debonded over time, which is convenient for material separation. It is very suitable for the field of semiconductors or electronic devices. When semiconductor materials and flexible electronic parts are processed, photodebonding pressure-sensitive adhesive can be used as a temporary protective film to protect semiconductor materials such as wafers and flexible electronic parts. It has high adhesion at the beginning and can protect the wafer from displacement, peeling or scattering during the grinding and cutting of semiconductor wafers and flexible electronic parts. However, after the processing is completed, this temporary protective film can be easily peeled off from the semiconductor wafer or flexible electronic parts, leaving no residual glue, without contaminating the wafer or flexible electronic parts, and improving the pick-up rate when picking up the wafer. At present, the photodebonding pressure-sensitive adhesives that can be seen on the market at home and abroad are basically solvent-based, have certain toxicity, are not environmentally friendly, and most of them come from Japan. In addition, the photodebonding adhesives prepared in China today can basically only be used in the field of glass cutting, and cannot be used in wafer cutting, which has higher requirements for residual glue. The debonding adhesives for wafer processing are monopolized by Japanese companies.

[0003] Chinese patent application 202110830636.9 discloses a photodegradable pressure-sensitive adhesive and a preparation method thereof. The photodegradable pressure-sensitive adhesive includes styrene-isoprene-styrene block copolymer, a functional monomer mixture, a polyamide resin, an acrylate copolymer, a photoinitiator 2-hydroxy-2-methyl-1-phenyl ketone, and a crosslinker. However, the scheme contains acrylate monomers, which are highly irritating and toxic, have poor storage stability, and the resin is a non-photosensitive resin, which is easy to overflow during use, thereby affecting the process yield.

[0004] Although the prior art discloses some solutions of latex films, these solutions often have poor water whitening resistance and also have shortcomings such as insufficient decrease in adhesion after exposure to light. Summary of the invention

[0005] The present invention aims to overcome at least one defect of the above-mentioned prior art and provide a photo-debonding pressure-sensitive adhesive latex and a preparation method thereof and an aqueous cationic photo-curable debonding pressure-sensitive adhesive, which can solve the problems of strong irritation, high toxicity, insufficient residual adhesive and decreased adhesion of traditional UV debonding adhesives, as well as water-resistant whitening of traditional latex films.

[0006] The technical solution adopted by the present invention is:

[0007] A method for preparing a photodegradable pressure-sensitive adhesive latex comprises the following steps:

[0008] Providing predetermined weight portions of soft monomer, hard monomer, functional monomer, and modified monomer, wherein, by weight, the hard monomer is 5-15 weight portions, the soft monomer is 40-60 weight portions, the functional monomer is 2-5 weight portions, and the modified monomer is 0.1-2 weight portions;

[0009] Preparing a pre-emulsion: mixing 2-4 parts by weight of emulsifier 1 and 10-30 parts by weight of water, adding weighed soft monomers, hard monomers, functional monomers and modified monomers, and mixing to obtain a pre-emulsion;

[0010] Preparation of a photodegradable pressure-sensitive adhesive latex: uniformly mixing 0.2-1 parts by weight of an emulsifier 2 and 30-70 parts by weight of water, adding 5-10% of the pre-emulsion based on the total mass of the pre-emulsion, adding a first initiator aqueous solution, polymerizing under the action of the first initiator, and after the reaction system emits blue light, heat-retaining the reaction for 10-40 minutes, then dripping the remaining pre-emulsion and the second initiator aqueous solution, continuing the reaction for 0.5-1.5 hours, and adjusting the pH value to 7-9 after the reaction is completed to obtain a photodegradable pressure-sensitive adhesive latex;

[0011] Wherein, the emulsifier 1 and the emulsifier 2 are selected from at least one of sodium allyloxysulfonate, ammonium allyloxypolyoxyethylene ether sulfate, and polyoxyethylene fatty acid ester; the modified monomer includes 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate, and the modified monomer accounts for 0.2-2.5% of the total monomer weight; the first initiator aqueous solution contains 0.03-0.1 parts by weight of the first initiator, and the second initiator aqueous solution contains 0.1-0.2 parts by weight of the second initiator.

[0012] When using emulsion-type acrylic pressure-sensitive adhesive, its use is restricted due to the poor water resistance caused by emulsifiers and hydrophilic monomers. The present invention provides a photodegradable pressure-sensitive adhesive emulsion, which adopts semi-continuous seed polymerization and cooperates with each other through the components, especially by adding 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate monomer containing both double bonds and epoxy groups, an epoxy group that can undergo a cationic reaction is introduced into the molecular chain, so that it reacts with the carboxyl group on the molecular chain to form a cross-linked structure, thereby improving the performance of the latex film. The pressure-sensitive adhesive emulsion obtained by adding modified monomers within the range has a greater peeling force and better water whitening resistance. The emulsion provided by the present invention has good stability and low gel rate. The pressure-sensitive adhesive prepared therefrom has good bonding performance and water whitening resistance, and the polar rigid ring structure opens under light, the bonding force decreases quickly, and no adhesive residue is left.

[0013] As a preferred embodiment, the emulsifier includes a mixture of sodium 3-allyloxy-1-hydroxy-propane sulfonate and ammonium allyloxy polyoxyethylene ether sulfate, and the mass ratio of the two is (0.8-1.5):1. More preferably, the mass ratio of sodium 3-allyloxy-1-hydroxy-propane sulfonate and ammonium allyloxy polyoxyethylene ether sulfate is (1.2-1.5):1. The emulsification system provided by this scheme has excellent emulsification and dispersion properties, can effectively prevent the aggregation and precipitation of particles, and has a low critical micelle concentration and high surface activity, and can achieve an effective emulsification effect at a low concentration. This scheme can make the emulsion more stable, can effectively stabilize the latex particles, and improve the water whitening resistance, chemical resistance and mechanical stability of the emulsion.

[0014] Among them, the hard monomer includes methyl methacrylate and / or styrene; the soft monomer includes one or more of ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate; and the functional monomer includes one or more of methacrylic acid, acrylic acid, acrylamide, and N-hydroxymethyl acrylamide.

[0015] As a preferred embodiment, the first initiator and the second initiator are respectively selected from one or more of azobisisobutylamidine hydrochloride, tert-butyl hydroperoxide, L(+)-ascorbic acid, potassium persulfate, sodium persulfate or ammonium persulfate.

[0016] As a preferred solution, the adding of weighed soft monomers, hard monomers, functional monomers and modified monomers and mixing them specifically includes: adding weighed soft monomers and hard monomers, fully emulsifying them, and then adding functional monomers and modified monomers and further mixing them.

[0017] As a preferred embodiment, in the step of preparing the photodegradable pressure-sensitive adhesive latex, the remaining pre-emulsion and the second initiator aqueous solution are added dropwise within 2 to 4 hours. After the addition is completed, the reaction is continued for 0.5 to 1.5 hours, the reaction system is cooled to 20-35°C, and the pH is adjusted to 7-9 to obtain the photodegradable pressure-sensitive adhesive latex.

[0018] A photodegradable pressure-sensitive adhesive latex is prepared by the preparation method.

[0019] A water-based cationic photo-debonding pressure-sensitive adhesive comprises a cationic initiator and the photo-debonding pressure-sensitive adhesive emulsion. The water-based cationic photo-debonding pressure-sensitive adhesive provided by the present invention can also be called water-based UV debonding adhesive or cationic UV debonding adhesive. The water-based UV debonding adhesive prepared by the present invention has the characteristics of high initial adhesion, high viscosity, fast debonding, and excellent water resistance (water whitening resistance). Compared with the oily UV debonding adhesive, the water-based UV debonding adhesive has many advantages such as safety, low toxicity, odorlessness, and easy operation. Compared with the traditional free radical curing pressure-sensitive adhesive, the cationic UV debonding adhesive in the present invention has the characteristics of low curing shrinkage, high hardness of the adhesive film after curing, and easy release, thereby improving the comprehensive performance of the material.

[0020] As a preferred embodiment, the cationic initiator is selected from one or more of diaryliodonium hexafluorophosphate, diaryliodonium hexafluoroantimonate, triarylsulfonium hexafluorophosphate, and triarylsulfonium hexafluoroantimonate.

[0021] As a preferred solution, the amount of the cationic initiator is 0.5-3% of the total mass of the pressure-sensitive adhesive latex.

[0022] As a preferred embodiment, the water-based cationic photodegradable pressure-sensitive adhesive has a water whitening resistance of level 1-2.

[0023] As a preferred solution, the peeling force of the aqueous cationic photodegradable pressure-sensitive adhesive on the stainless steel plate is greater than 550 gf.

[0024] As a preferred solution, the peeling force of the aqueous cationic photodegradable pressure-sensitive adhesive on the stainless steel plate is less than 20 gf when irradiated with 400 mJ of energy.

[0025] The beneficial effects of the present invention are as follows: the photodegradable pressure-sensitive adhesive latex of the present invention adopts semi-continuous seed polymerization, and polymerizes by selecting a special emulsifier and a functional monomer and a 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate monomer containing a double bond and an epoxy group as a modified monomer, so that the carboxyl groups on the molecular chain react to form a cross-linked structure, thereby improving the performance of the latex film; the modified monomer is added within a range, and the pressure-sensitive adhesive latex obtained by the obtained pressure-sensitive adhesive has a greater peeling force and better water whitening resistance; the emulsion provided by the present invention has good stability and a low gel rate, and the pressure-sensitive adhesive prepared by the emulsion has good bonding performance and water whitening resistance, and the polar rigid ring structure opens under light, the bonding force decreases quickly, and no adhesive residue is left. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention are further described in detail below.

[0027] Raw materials: 3-allyloxy-1-hydroxy-propane sulfonate sodium (COPS-1), allyloxy polyoxyethylene ether ammonium sulfate (SR-10).

[0028] Unless otherwise specified, the raw materials described in the present invention are all common commercially available products.

[0029] The dosages described in the present invention are all parts by weight unless otherwise specified. Example 1

[0030] (1) Add 24g of deionized water, 1.2g of SR-10 emulsifier and 1.45g of COPS-1 emulsifier to a beaker, adjust the stirring speed to 400r / min, and stir for 20min to fully disperse the emulsifier in the water. Increase the speed to 600r / min, pour 8g of methyl methacrylate, 51g of butyl acrylate and 1.6g of isooctyl acrylate into the beaker, and after sufficient emulsification, add 2.4g of functional monomer α-methyl acrylic acid and 1.5g of acrylic acid, and 0.1576g of modified monomer 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate. Continue stirring for 30min to obtain a stable pre-emulsion.

[0031] (2) Add 62g of deionized water and 0.57g of SR-10 emulsifier to a flask equipped with a thermometer, a stirring paddle and a condenser tube, heat and stir in an oil bath at 80°C for 20min, then take 5% of the pre-emulsion and add it to the flask at once, dissolve 0.05g of sodium persulfate in 1.5g of deionized water and add it to the flask, wait for the reaction system to emit blue light, keep warm for 10 minutes, drip the remaining 95% of the pre-emulsion with a constant pressure funnel within 3h, and at the same time drip 4.5g of a deionized water solution containing 0.15g of sodium persulfate. After all the dripping is completed, keep warm for one hour, and after cooling to room temperature, adjust the solution pH to 7-9 with ammonia water to obtain an aqueous cationic photodegradable pressure-sensitive adhesive latex.

[0032] (3) Place the corona-treated side of the PET polyester film upward on a coating plate, take a certain amount of the aqueous cationic photodegradable pressure-sensitive adhesive latex, add 2% of the total mass of the emulsion as a cationic photoinitiator 4-(phenylthio)phenyl diphenylsulfonium hexafluorophosphate, mix well, use a wire rod coater to evenly coat a certain amount of the latex glue on the surface of the PET film, put the film into an oven at 80°C and bake it, take it out after 20 minutes to obtain a dry film of 15-20 um, and use a crawler-type UV curing machine to irradiate with UV light to obtain a pressure-sensitive adhesive. Example 2

[0033] (1) Add 24g of deionized water, 1.2g of SR-10 emulsifier and 1.45g of COPS-1 emulsifier to a beaker, adjust the stirring speed to 400r / min, and stir for 20min to fully disperse the emulsifier in the water. Increase the speed to 600r / min, pour 8g of methyl methacrylate, 51g of butyl acrylate, and 1.6g of isooctyl acrylate into the beaker, and after sufficient emulsification, add 2.4g of functional monomer α-methyl acrylic acid, 1.5g of acrylic acid, and 0.552g of modified monomer 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate. Continue stirring for 30min to obtain a stable pre-emulsion.

[0034] (2) Add 62g of deionized water and 0.57g of SR-10 emulsifier to a flask equipped with a thermometer, a stirring paddle and a condenser tube, heat and stir in an oil bath at 80°C for 20min, then take 5% of the pre-emulsion and add it to the flask at once, dissolve 0.05g of sodium persulfate in 1.5g of deionized water and add it to the flask, wait for the reaction system to emit blue light, keep warm for 10 minutes, drip the remaining 95% of the pre-emulsion with a constant pressure funnel within 3h, and at the same time drip 4.5g of a deionized water solution containing 0.15g of sodium persulfate. After all the dripping is completed, keep warm for one hour, and after cooling to room temperature, adjust the solution pH to 7-9 with ammonia water to obtain an aqueous cationic photodegradable pressure-sensitive adhesive latex.

[0035] (3) Place the PET polyester film with the corona treated side facing up on the coating plate, take a certain amount of emulsion, add 2% of the total mass of the emulsion as a cationic photoinitiator 4-(phenylthio)phenyl diphenylsulfonium hexafluorophosphate, mix well, and use a wire rod coater to evenly coat a certain amount of the emulsion glue on the surface of the PET film. Put the film into an oven at 80°C and bake it. Take it out after 20 minutes to obtain a dry film of 15-20 um, and use a crawler-type UV curing machine to irradiate it with UV light to obtain a pressure-sensitive adhesive. Example 3

[0036] (1) Add 24g of deionized water, 1.2g of SR-10 emulsifier and 1.45g of COPS-1 emulsifier to a beaker, adjust the stirring speed to 400r / min, and stir for 20min to fully disperse the emulsifier in the water. Increase the speed to 600r / min, pour 8g of methyl methacrylate, 51g of butyl acrylate and 1.6g of isooctyl acrylate into the beaker, and after fully emulsifying, add 2.4g of functional monomer α-methyl acrylic acid, 1.5g of acrylic acid and 1.576g of modified monomer 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate. Continue stirring for 30min to obtain a stable pre-emulsion.

[0037] (2) Add 62g of deionized water and 0.57g of SR-10 emulsifier to a flask equipped with a thermometer, a stirring paddle and a condenser tube, heat and stir in an oil bath at 80°C for 20min, then take 5% of the pre-emulsion and add it to the flask at once, dissolve 0.05g of sodium persulfate in 1.5g of deionized water and add it to the flask. After the solution in the flask turns blue within 10 minutes, drip the remaining 95% of the pre-emulsion with a constant pressure funnel within 3h, and at the same time drip 4.5g of a deionized water solution containing 0.15g of sodium persulfate. After all the dripping is completed, keep warm for one hour, and after cooling to room temperature, adjust the solution pH to 7-9 with ammonia water to obtain an aqueous cationic photodegradable pressure-sensitive adhesive latex.

[0038] (3) Place the PET polyester film with the corona treated side facing up on the coating plate, take a certain amount of emulsion, add 2% of the total mass of the emulsion as a cationic photoinitiator 4-(phenylthio)phenyl diphenylsulfonium hexafluorophosphate, mix well, and use a wire rod coater to evenly coat a certain amount of the emulsion glue on the surface of the PET film. Put the film into an oven at 80°C and bake it. Take it out after 20 minutes to obtain a dry film of 15-20 um, and use a crawler-type UV curing machine to irradiate it with UV light to obtain a pressure-sensitive adhesive. Example 4

[0039] (1) Add 14g of deionized water, 0.8g of SR-10 emulsifier and 1.2g of COPS-1 emulsifier to a beaker, adjust the stirring speed to 300r / min, and stir for 15min to fully disperse the emulsifier in the water. Increase the speed to 600r / min, pour 12g of methyl methacrylate, 42g of ethyl acrylate, and 5g of 2-ethylhexyl acrylate into the beaker, and after fully emulsifying, add 1.3g of functional monomer α-methylacrylate, 2.5g of acrylic acid, and 0.5g of modified monomer 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate. Continue stirring for 25min to obtain a stable pre-emulsion.

[0040] (2) Add 32g of deionized water and 0.2g of SR-10 emulsifier to a flask equipped with a thermometer, a stirring paddle and a condenser, heat and stir in an oil bath at 75°C for 20min, then take 10% of the pre-emulsion and add it to the flask at once, dissolve 0.05g of sodium persulfate in 1.5g of deionized water and add it to the flask. After the solution in the flask turns blue within 10 minutes, drip the remaining 90% of the pre-emulsion with a constant pressure funnel within 2.5h, and at the same time drip 4.5g of a deionized water solution containing 0.13g of sodium persulfate. After all the dripping is completed, keep warm for one hour, and after cooling to room temperature, adjust the solution pH to 7-9 with ammonia water to obtain an aqueous cationic photodegradable pressure-sensitive adhesive latex.

[0041] (3) Place the PET polyester film with the corona-treated side facing up on a coating plate, take a certain amount of emulsion, add 3% of the total mass of the emulsion as a cationic photoinitiator 4-(phenylthio)phenyl diphenylsulfonium hexafluorophosphate, mix well, and use a wire rod coater to evenly coat a certain amount of the emulsion glue on the surface of the PET film. Put the film into an oven at 80°C and bake it. Take it out after 20 minutes to obtain a dry film of 15-20 um, and use a crawler-type UV curing machine to irradiate it with UV light to obtain a pressure-sensitive adhesive. Example 5

[0042] (1) Add 30g of deionized water, 2g of SR-10 emulsifier and 3g of COPS-1 emulsifier to a beaker, adjust the stirring speed to 400r / min, and stir for 20min to fully disperse the emulsifier in the water. Increase the speed to 600r / min, pour 15g of methyl methacrylate, 58g of butyl acrylate and 1.8g of isooctyl acrylate into the beaker, and after sufficient emulsification, add 3g of functional monomer α-methyl acrylic acid and 1.88g of acrylic acid, and 2g of modified monomer 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate. Continue stirring for 30min to obtain a stable pre-emulsion.

[0043] (2) Add 70g of deionized water and 1g of SR-10 emulsifier to a flask equipped with a thermometer, a stirring paddle and a condenser, heat and stir in an oil bath at 80°C for 20min, then take 8% of the pre-emulsion and add it to the flask at once, dissolve 0.1g of sodium persulfate in 3g of deionized water and add it to the flask, wait for the reaction system to emit blue light, keep warm for 20 minutes, drip the remaining 92% of the pre-emulsion with a constant pressure funnel within 4h, and at the same time drip 6g of a deionized water solution containing 0.2g of sodium persulfate. After all the dripping is completed, keep warm for one hour, and after cooling to room temperature, adjust the solution pH to 7-9 with ammonia water to obtain an aqueous cationic photodegradable pressure-sensitive adhesive latex.

[0044] (3) Place the corona-treated side of the PET polyester film upward on a coating plate, take a certain amount of the aqueous cationic photodegradable pressure-sensitive adhesive latex, add 2% of the total mass of the emulsion as a cationic photoinitiator 4-(phenylthio)phenyl diphenylsulfonium hexafluorophosphate, mix well, use a wire rod coater to evenly coat a certain amount of the latex glue on the surface of the PET film, put the film into an oven at 80°C and bake it, take it out after 20 minutes to obtain a dry film of 15-20 um, and use a crawler-type UV curing machine to irradiate with UV light to obtain a pressure-sensitive adhesive. Example 6

[0045] (1) Add 10g of deionized water, 0.9g of SR-10 emulsifier and 1.1g of COPS-1 emulsifier to a beaker, adjust the stirring speed to 400r / min, and stir for 20min to fully disperse the emulsifier in the water. Increase the speed to 600r / min, pour 5g of methyl methacrylate, 38.8g of butyl acrylate, and 1.2g of isooctyl acrylate into the beaker, and after sufficient emulsification, add 1.23g of functional monomer α-methacrylic acid and 0.77g of acrylic acid, and 0.394g of modified monomer 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate. Continue stirring for 30min to obtain a stable pre-emulsion.

[0046] (2) Add 30g of deionized water and 0.3g of SR-10 emulsifier to a flask equipped with a thermometer, a stirring paddle and a condenser, heat and stir in an oil bath at 80°C for 20min, then take 8% of the pre-emulsion and add it to the flask at once, dissolve 0.03g of sodium persulfate in 0.9g of deionized water and add it to the flask, wait for the reaction system to emit blue light, keep warm for 20 minutes, drip the remaining 92% of the pre-emulsion with a constant pressure funnel within 3h, and at the same time drip 3g of a deionized water solution containing 0.1g of sodium persulfate. After all the dripping is completed, keep warm for one hour, and after cooling to room temperature, adjust the solution pH to 7-9 with ammonia water to obtain an aqueous cationic photodegradable pressure-sensitive adhesive latex.

[0047] (3) Place the corona-treated side of the PET polyester film upward on a coating plate, take a certain amount of the aqueous cationic photodegradable pressure-sensitive adhesive latex, add 2% of the total mass of the emulsion as a cationic photoinitiator 4-(phenylthio)phenyl diphenylsulfonium hexafluorophosphate, mix well, use a wire rod coater to evenly coat a certain amount of the latex glue on the surface of the PET film, put the film into an oven at 80°C and bake it, take it out after 20 minutes to obtain a dry film of 15-20 um, and use a crawler-type UV curing machine to irradiate with UV light to obtain a pressure-sensitive adhesive. Example 7

[0048] The only difference between Example 7 and Example 1 is that the emulsifier uses SR-10 of equal quality instead of COPS-1. Example 8

[0049] Example 8 is similar to Example 1 except that the emulsifier uses polyoxyethylene laurate-6 ester of equal quality instead of COPS-1. Comparative Example 1

[0050] The difference between Comparative Example 1 and Example 1 is that the modified monomer 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate is not added. Comparative Example 2

[0051] The difference between Comparative Example 2 and Example 1 is that the added amount of the modified monomer 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate is 2.3 g. Comparative Example 3

[0052] The only difference between Comparative Example 3 and Example 1 is that both emulsifiers SR-10 and COPS-1 are replaced by sodium lauryl sulfate. Comparative Example 4

[0053] The difference between Comparative Example 4 and Example 1 is that the modified monomer uses 4-acryloylmorpholine in an equal molar amount instead of 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate. test

[0054] 1. UV light energy control

[0055] The pressure-sensitive adhesive was irradiated with different energies by adjusting the speed of the transmission track of a track-type UV curing machine (RW-UVA302-30, Shenzhen Runwo Electromechanical Co., Ltd.), and the UV energy meter (UV-150, UV-DESGN, Germany) was used to detect and control the UV irradiation energy.

[0056] 2. Peel strength test

[0057] The test was carried out according to the standard of GB / T 2792-2014. A universal testing machine (KJ-1065, Dongguan Kejian Instrument Co., Ltd.) was used to measure the peeling force of the pressure-sensitive adhesive sample on the stainless steel plate. The tensile speed during the test was 30 cm / min and the tensile angle was 180°.

[0058] 3. Water whitening resistance test

[0059] Immerse the pressure-sensitive adhesive sample in tap water at room temperature (about 25°C), with the adhesive side facing downward, and observe the whitening of the pressure-sensitive adhesive film after 24 hours. The test results are expressed in 1-5 levels, where 1 means no whitening at all and 5 means complete whitening.

[0060] 4. Wafer residual adhesive test

[0061] The pressure-sensitive adhesive sample was adhered to the wafer and peeled off using a universal testing machine (KJ-1065, Dongguan Kejian Instrument Co., Ltd.), and then a 500x magnifying glass was used to observe whether there was residual adhesive on the wafer.

[0062] Table 1 Peeling performance test and water whitening resistance test of the aqueous cationic photodegradable pressure-sensitive adhesives prepared in Examples 1 to 8 of the present invention and Comparative Examples 1 to 4.

[0063] Table 1

[0064] From the test results in the above table, it can be seen that the photodebonding pressure-sensitive adhesive prepared according to the present invention has the characteristics of high initial adhesion, high viscosity and excellent water whitening resistance, and the peeling force decreases significantly after UV irradiation, and has a good debonding effect.

[0065] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation methods of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the claims of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a photodegradable pressure-sensitive adhesive latex, characterized in that: The steps include: Providing predetermined weight portions of soft monomer, hard monomer, functional monomer, and modified monomer, wherein, by weight, the hard monomer is 5-15 weight portions, the soft monomer is 40-60 weight portions, the functional monomer is 2-5 weight portions, and the modified monomer is 0.1-2 weight portions; Preparing a pre-emulsion: mixing 2-4 parts by weight of emulsifier 1 and 10-30 parts by weight of water, adding weighed soft monomers, hard monomers, functional monomers and modified monomers, and mixing to obtain a pre-emulsion; Preparation of a photodegradable pressure-sensitive adhesive latex: uniformly mixing 0.2-1 parts by weight of an emulsifier 2 and 30-70 parts by weight of water, adding 5-10% of the pre-emulsion based on the total mass of the pre-emulsion, adding a first initiator aqueous solution, polymerizing under the action of the first initiator, and after the reaction system emits blue light, heat-retaining the reaction for 10-40 minutes, then dripping the remaining pre-emulsion and the second initiator aqueous solution, continuing the reaction for 0.5-1.5 hours, and adjusting the pH value to 7-9 after the reaction is completed to obtain a photodegradable pressure-sensitive adhesive latex; Wherein, the emulsifier 1 and the emulsifier 2 are selected from at least one of sodium allyloxysulfonate, ammonium allyloxypolyoxyethylene ether sulfate, and polyoxyethylene fatty acid ester; the modified monomer includes 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate, and the modified monomer accounts for 0.2-2.5% of the total monomer weight; the first initiator aqueous solution contains 0.03-0.1 parts by weight of the first initiator, and the second initiator aqueous solution contains 0.1-0.2 parts by weight of the second initiator.

2. The method for preparing the photodegradable pressure-sensitive adhesive emulsion according to claim 1, characterized in that: The emulsifier is a mixture of sodium 3-allyloxy-1-hydroxy-propane sulfonate and ammonium allyloxy polyoxyethylene ether sulfate, and the mass ratio of the two is (0.8-1.5):

1.

3. The method for preparing the photodegradable pressure-sensitive adhesive emulsion according to claim 1, characterized in that: The hard monomer includes methyl methacrylate and / or styrene; the soft monomer includes one or more of ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and octyl acrylate; and the functional monomer includes one or more of methacrylic acid, acrylic acid, acrylamide, and N-hydroxymethyl acrylamide.

4. The method for preparing the photodegradable pressure-sensitive adhesive emulsion according to claim 1, characterized in that: The first initiator and the second initiator are respectively selected from one or more of azobisisobutylamidine hydrochloride, azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, tert-butyl hydroperoxide, L(+)-ascorbic acid, methyl ethyl ketone peroxide, sodium persulfate or ammonium persulfate.

5. The method for preparing the photodegradable pressure-sensitive adhesive emulsion according to claim 1, characterized in that: The adding of weighed soft monomers, hard monomers, functional monomers and modified monomers for mixing specifically includes: adding weighed soft monomers and hard monomers, fully emulsifying, and then adding functional monomers and modified monomers for further mixing.

6. The method for preparing the photodegradable pressure-sensitive adhesive emulsion according to claim 1, characterized in that: In the step of preparing the photodegradable pressure-sensitive adhesive latex, the remaining pre-emulsion and the second initiator aqueous solution are added dropwise within 2 to 4 hours. After the addition is completed, the reaction is continued for 0.5 to 1.5 hours, the reaction system is cooled to 20-35° C., and the pH is adjusted to 7-9 to obtain the photodegradable pressure-sensitive adhesive latex.

7. A photodegradable pressure-sensitive adhesive latex, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 6.

8. A water-based cationic photodegradable pressure-sensitive adhesive, characterized in that: The invention comprises a cationic initiator and the photodegradable pressure-sensitive adhesive latex as claimed in claim 7.

9. The aqueous cationic photodegradable pressure-sensitive adhesive according to claim 8, characterized in that: The cationic initiator is selected from one or more of diaryliodonium hexafluorophosphate, diaryliodonium hexafluoroantimonate, triarylsulfonium hexafluorophosphate, and triarylsulfonium hexafluoroantimonate.

10. The aqueous cationic photodegradable pressure-sensitive adhesive according to claim 8 or 9, characterized in that: The amount of the cationic initiator is 0.5-3% of the total mass of the pressure-sensitive adhesive latex.

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