Photodegradable pressure sensitive adhesive latex and method of making same and waterborne cationic photodegradable pressure sensitive adhesive

Abstract

The application discloses a kind of photodegradable pressure-sensitive adhesive emulsion and its preparation method and water-based cationic photodegradable pressure-sensitive adhesive.The raw materials of the water-based photodegradable pressure-sensitive adhesive emulsion of the application are composed of emulsifier, water, soft monomer, hard monomer, functional monomer and modified monomer.By selecting special emulsifier, functional monomer and modified monomer, the emulsion prepared has higher stability, can effectively stabilize latex particles, and improve the water whitening resistance, chemical resistance and mechanical stability of the emulsion.The emulsion can be applied to photodegradable pressure-sensitive adhesive.Under ultraviolet irradiation, the photodegradable pressure-sensitive adhesive can quickly form a film, has no residual glue, and the adhesive force decreases significantly over time.The photodegradable pressure-sensitive adhesive prepared by the application has the characteristics of high initial adhesion, high tack, fast debonding and excellent water resistance, and also has the advantages of safety, low toxicity, odorless and easy operation.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a photolytic adhesive pressure-sensitive latex, its preparation method, and an aqueous cationic photolytic adhesive pressure-sensitive latex. Background Technology

[0002] Photolytic adhesive pressure-sensitive adhesive (PAP) is a new type of adhesive material that initially exhibits good adhesion but rapidly debonds over time, facilitating material separation. It is highly suitable for the semiconductor and electronic device industries. During the processing of semiconductor materials and flexible electronic components, PAP can serve as a temporary protective film to protect semiconductor materials such as wafers and flexible electronic components. It initially possesses high adhesion, protecting wafers from displacement, peeling, or scattering during grinding and cutting. However, after processing, this temporary protective film can be easily peeled off from the semiconductor wafer or flexible electronic component without leaving residue or contaminating the wafer or flexible electronic component, thus improving the pick-up rate during wafer sorting. Currently, most PAPs available on the market, both domestically and internationally, are solvent-based, possessing a certain degree of toxicity and being environmentally unfriendly. Furthermore, most PAPs produced domestically are currently only suitable for glass cutting and cannot be applied to wafer cutting, where higher requirements for adhesive residue are necessary. The PAP market for wafer processing is monopolized by Japanese companies.

[0003] Chinese patent application 202110830636.9 discloses a photolytic adhesive pressure-sensitive adhesive and its preparation method. The photolytic adhesive pressure-sensitive adhesive comprises a styrene-isoprene-styrene block copolymer, a mixture of functional monomers, a polyamide resin, an acrylate copolymer, a photoinitiator 2-hydroxy-2-methyl-1-phenyl ketone, and a crosslinking agent. However, this method contains acrylate monomers, which are highly irritating and toxic, have poor storage stability, and the resin is a non-photosensitive resin, making it prone to overflow during use, thus affecting the process yield.

[0004] While existing technologies disclose some latex film solutions, these solutions often have poor water resistance and whitening properties, and also have shortcomings such as insufficient decrease in adhesion after light exposure. Summary of the Invention

[0005] The present invention aims to overcome at least one of the defects of the prior art and provides a photopolymerizable pressure-sensitive adhesive emulsion, its preparation method and an aqueous cationic photocurable polymerizable pressure-sensitive adhesive, which can solve the problems of strong irritation, high toxicity, insufficient residual adhesive and adhesion, and water whitening of traditional latex films.

[0006] The technical solution adopted in this invention is:

[0007] A method for preparing a photolytically degradable pressure-sensitive adhesive emulsion includes the following steps:

[0008] Provide soft monomers, hard monomers, functional monomers, and modified monomers in predetermined weight parts, wherein, by weight parts, there are 5-15 parts of hard monomers, 40-60 parts of soft monomers, 2-5 parts of functional monomers, and 0.1-2 parts of modified monomers.

[0009] Preparation of preemulsion: Mix 2-4 parts by weight of emulsifier 1 and 10-30 parts by weight of water, add weighed soft monomers, hard monomers, functional monomers and modified monomers and mix to obtain preemulsion;

[0010] Preparation of photolytic adhesive pressure-sensitive latex: Mix 0.2-1 parts by weight of emulsifier 2 and 30-70 parts by weight of water evenly, add 5-10% of the pre-emulsion (based on the total mass of the pre-emulsion), add an aqueous solution of the first initiator, and polymerize under the action of the first initiator. After the reaction system shows blue light, keep the reaction at a warm temperature for 10-40 minutes, then add the remaining pre-emulsion and the aqueous solution of the second initiator dropwise, and continue the reaction for 0.5-1.5 hours. After the reaction is completed, adjust the pH value to 7-9 to obtain the photolytic adhesive pressure-sensitive latex.

[0011] Wherein, emulsifier 1 and emulsifier 2 are selected from at least one of sodium allyl sulfonate, ammonium allyl oxyethylene ether sulfate, and polyoxyethylene fatty acid ester; the modified monomer includes methyl 7-oxabicyclo[4.1.0]heptane-3-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] The use of emulsion-type acrylic pressure-sensitive adhesives is limited by the reduced water resistance caused by emulsifiers and hydrophilic monomers. This invention provides a photolytic adhesive pressure-sensitive adhesive emulsion using semi-continuous seed polymerization. Through the synergistic effect of its components, particularly the addition of 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate monomer containing both double bonds and epoxy groups, cationicly reactive epoxy groups are introduced into the molecular chain. These epoxy groups react with carboxyl groups on the molecular chain to form a cross-linked structure, improving the performance of the latex film. The modified monomers within the specified range result in pressure-sensitive adhesive emulsions with greater peel strength and better water-whitening resistance. The emulsion provided by this invention exhibits good stability and low gelation rate. The pressure-sensitive adhesive prepared from it has excellent adhesion and water-whitening resistance. Furthermore, under light irradiation, the polar rigid ring structure opens, resulting in a rapid decrease in adhesive strength and no residue.

[0013] As a preferred embodiment, the emulsifier comprises a mixture of sodium 3-allyloxy-1-hydroxy-propanesulfonate and allyloxy polyoxyethylene ether ammonium sulfate in a mass ratio of (0.8–1.5):1. More preferably, the mass ratio of sodium 3-allyloxy-1-hydroxy-propanesulfonate to allyloxy polyoxyethylene ether ammonium sulfate is (1.2–1.5):1. The emulsion system provided by this embodiment exhibits excellent emulsifying and dispersing properties, effectively preventing particle aggregation and sedimentation. It also possesses a low critical micelle concentration and high surface activity, achieving effective emulsification even at low concentrations. This embodiment enhances emulsion stability, effectively stabilizing latex particles and improving the emulsion's resistance to water whitening, chemical resistance, and mechanical stability.

[0014] The hard monomers include methyl methacrylate and / or styrene; the soft monomers include one or more of ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate; and the functional monomers include one or more of methacrylic acid, acrylic acid, acrylamide, and N-hydroxymethylacrylamide.

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

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

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

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

[0019] A water-based cationic photolytic adhesive pressure-sensitive adhesive includes a cationic initiator and the photolytic adhesive pressure-sensitive adhesive emulsion. The water-based cationic photolytic adhesive pressure-sensitive adhesive provided by this invention can also be called a water-based UV adhesive or a cationic UV adhesive. The water-based UV adhesive prepared by this invention has the characteristics of high initial tack, high viscosity, fast detack, and excellent water resistance (water-resistant whitening). Compared with oil-based UV adhesives, water-based UV adhesives have many advantages such as safety, low toxicity, odorless, and easy operation. Compared with traditional free radical curing pressure-sensitive adhesives, the cationic UV adhesive of this invention has the characteristics of low curing shrinkage, high hardness of the cured film, and easy release, thus improving the overall performance of the material.

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

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

[0022] As a preferred embodiment, the water-based cationic photolytic pressure-sensitive adhesive exhibits a water whitening resistance grade of 1-2.

[0023] As a preferred embodiment, the water-based cationic photolytic pressure-sensitive adhesive has a peel force greater than 550 gf on stainless steel plates.

[0024] As a preferred embodiment, the water-based cationic photolytic pressure-sensitive adhesive exhibits a peel force of less than 20 gf on stainless steel plates when irradiated with 400 mJ of energy.

[0025] The beneficial effects of this invention are as follows: The photolytic adhesive pressure-sensitive latex of this invention adopts semi-continuous seed polymerization. By selecting special emulsifiers and functional monomers, as well as 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate monomer containing double bonds and epoxy groups as modifying monomers, the carboxyl groups on the molecular chain react to form a cross-linked structure, thereby improving the performance of the latex film. With the addition of modifying monomers within the specified range, the pressure-sensitive latex obtained has greater peel force and better water-whitening resistance. The latex provided by this invention has good stability and low gelation rate. The pressure-sensitive adhesive prepared from it has good adhesion and water-whitening resistance. Moreover, under light irradiation, the polar rigid ring structure opens, the adhesion decreases quickly, and no adhesive residue remains. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below.

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

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

[0029] Unless otherwise specified, all dosages mentioned in this invention are parts by weight.

[0030] Example 1

[0031] (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 stirring speed to 600r / min and pour 8g of methyl methacrylate, 51g of butyl acrylate, and 1.6g of isooctyl acrylate into the beaker. After fully emulsifying, add 2.4g of functional monomer α-methacrylic acid, 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.

[0032] (2) Add 62g of deionized water and 0.57g of SR-10 emulsifier to a flask equipped with a thermometer, stirrer, and condenser. Heat and stir in an oil bath at 80℃ for 20min. Then, add 5% of the pre-emulsion to the flask all at once. Dissolve 0.05g of sodium persulfate in 1.5g of deionized water and add it to the flask. After the reaction system shows blue light, keep it warm for 10 minutes. Add the remaining 95% of the pre-emulsion dropwise over 3 hours using a constant pressure funnel, while simultaneously adding 4.5g of a deionized water solution containing 0.15g of sodium persulfate. After all the addition is complete, keep it warm for one hour. After cooling to room temperature, adjust the pH of the solution to 7-9 with ammonia water to obtain the aqueous cationic photolytic adhesive pressure-sensitive latex.

[0033] (3) Place the corona-treated PET polyester film on a coating plate with the corona-treated side facing up. Take a certain amount of the water-based cationic photolytic adhesive pressure-sensitive latex and add 2% of the total mass of the latex as cationic photoinitiator 4-(phenylthio)phenyldiphenylthionium hexafluorophosphate. After mixing evenly, use a wire bar coater to evenly coat a certain amount of the latex onto the surface of the PET film. Place the film in an oven at 80°C and bake for 20 minutes. After baking, take it out to obtain a dry film of 15-20 μm. Use a conveyor belt UV curing machine to irradiate with ultraviolet light to obtain the pressure-sensitive adhesive.

[0034] Example 2

[0035] (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 stirring speed to 600r / min and pour 8g of methyl methacrylate, 51g of butyl acrylate, and 1.6g of isooctyl acrylate into the beaker. After fully emulsifying, add 2.4g of functional monomer α-methacrylic 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.

[0036] (2) Add 62g of deionized water and 0.57g of SR-10 emulsifier to a flask equipped with a thermometer, stirrer, and condenser. Heat and stir in an oil bath at 80℃ for 20min. Then, add 5% of the pre-emulsion to the flask all at once. Dissolve 0.05g of sodium persulfate in 1.5g of deionized water and add it to the flask. After the reaction system shows blue light, keep it warm for 10 minutes. Add the remaining 95% of the pre-emulsion dropwise over 3 hours using a constant pressure funnel, while simultaneously adding 4.5g of a deionized water solution containing 0.15g of sodium persulfate. After all the addition is complete, keep it warm for one hour. After cooling to room temperature, adjust the pH of the solution to 7-9 with ammonia water to obtain the aqueous cationic photolytic adhesive pressure-sensitive latex.

[0037] (3) Place the corona-treated PET polyester film on a coating plate with the corona-treated side facing up. Take a certain amount of emulsion and add 2% of the total mass of the emulsion cationic photoinitiator 4-(phenylthio)phenyldiphenylthionium hexafluorophosphate. After mixing evenly, use a wire bar coater to evenly coat a certain amount of emulsion adhesive onto the surface of the PET film. Place the film in an oven at 80°C and bake for 20 minutes. After baking, take it out to obtain a dry film of 15-20 μm. Use a conveyor belt UV curing machine to irradiate with UV light to obtain pressure-sensitive adhesive.

[0038] Example 3

[0039] (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 stirring speed to 600r / min and pour 8g of methyl methacrylate, 51g of butyl acrylate, and 1.6g of isooctyl acrylate into the beaker. After fully emulsifying, add 2.4g of functional monomer α-methacrylic 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.

[0040] (2) Add 62g of deionized water and 0.57g of SR-10 emulsifier to a flask equipped with a thermometer, stirrer, and condenser. Heat and stir in an oil bath at 80℃ for 20min. Then, add 5% of the pre-emulsion to the flask all 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, add the remaining 95% of the pre-emulsion dropwise over 3 hours using a constant pressure funnel. At the same time, add 4.5g of a deionized water solution containing 0.15g of sodium persulfate. After all the addition is complete, keep the solution at this temperature for one hour. After cooling to room temperature, adjust the pH of the solution to 7-9 with ammonia water to obtain the aqueous cationic photolytic adhesive pressure-sensitive latex.

[0041] (3) Place the corona-treated PET polyester film on a coating plate with the corona-treated side facing up. Take a certain amount of emulsion and add 2% of the total mass of the emulsion cationic photoinitiator 4-(phenylthio)phenyldiphenylthionium hexafluorophosphate. After mixing evenly, use a wire bar coater to evenly coat a certain amount of emulsion adhesive onto the surface of the PET film. Place the film in an oven at 80°C and bake for 20 minutes. After baking, take it out to obtain a dry film of 15-20 μm. Use a conveyor belt UV curing machine to irradiate with UV light to obtain pressure-sensitive adhesive.

[0042] Example 4

[0043] (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 ensure the emulsifier is fully dispersed in the water. Increase the stirring speed to 600r / min and pour 12g of methyl methacrylate, 42g of ethyl acrylate, and 5g of 2-ethylhexyl acrylate into the beaker. After thorough emulsification, add 1.3g of functional monomer α-methacrylic acid, 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.

[0044] (2) Add 32g of deionized water and 0.2g of SR-10 emulsifier to a flask equipped with a thermometer, stirrer, and condenser. Heat and stir in an oil bath at 75℃ for 20 minutes. Then, add 10% of the pre-emulsion to the flask all 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, add the remaining 90% of the pre-emulsion dropwise over 2.5 hours using a constant pressure funnel. At the same time, add 4.5g of a deionized water solution containing 0.13g of sodium persulfate. After all the addition is complete, keep the solution at this temperature for one hour. After cooling to room temperature, adjust the pH of the solution to 7-9 with ammonia water to obtain the aqueous cationic photolytic adhesive pressure-sensitive latex.

[0045] (3) Place the corona-treated PET polyester film on a coating plate with the corona-treated side facing up. Take a certain amount of emulsion and add 3% of the total mass of the emulsion cationic photoinitiator 4-(phenylthio)phenyldiphenylthionium hexafluorophosphate. After mixing evenly, use a wire bar coater to evenly coat a certain amount of emulsion adhesive onto the surface of the PET film. Place the film in an oven at 80°C and bake for 20 minutes. After baking, take it out to obtain a dry film of 15-20 μm. Use a conveyor belt UV curing machine to irradiate with ultraviolet light to obtain pressure-sensitive adhesive.

[0046] Example 5

[0047] (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 stirring speed to 600r / min and pour 15g of methyl methacrylate, 58g of butyl acrylate, and 1.8g of isooctyl acrylate into the beaker. After fully emulsifying, add 3g of functional monomer α-methacrylic acid, 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.

[0048] (2) Add 70g of deionized water and 1g of SR-10 emulsifier to a flask equipped with a thermometer, stirrer, and condenser. Heat and stir in an oil bath at 80℃ for 20min. Then, add 8% of the pre-emulsion to the flask all at once. Dissolve 0.1g of sodium persulfate in 3g of deionized water and add it to the flask. After the reaction system shows blue light, keep it warm for 20min. Add the remaining 92% of the pre-emulsion dropwise over 4h using a constant pressure funnel, while simultaneously adding 6g of a deionized water solution containing 0.2g of sodium persulfate. After all the addition is complete, keep it warm for one hour. After cooling to room temperature, adjust the pH of the solution to 7-9 with ammonia water to obtain the aqueous cationic photolytic adhesive pressure-sensitive latex.

[0049] (3) Place the corona-treated PET polyester film on a coating plate with the corona-treated side facing up. Take a certain amount of the water-based cationic photolytic adhesive pressure-sensitive latex and add 2% of the total mass of the latex as cationic photoinitiator 4-(phenylthio)phenyldiphenylthionium hexafluorophosphate. After mixing evenly, use a wire bar coater to evenly coat a certain amount of the latex onto the surface of the PET film. Place the film in an oven at 80°C and bake for 20 minutes. After baking, take it out to obtain a dry film of 15-20 μm. Use a conveyor belt UV curing machine to irradiate with ultraviolet light to obtain the pressure-sensitive adhesive.

[0050] Example 6

[0051] (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 stirring speed to 600r / min and pour 5g of methyl methacrylate, 38.8g of butyl acrylate, and 1.2g of isooctyl acrylate into the beaker. After fully emulsifying, add 1.23g of functional monomer α-methacrylic acid, 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.

[0052] (2) Add 30g of deionized water and 0.3g of SR-10 emulsifier to a flask equipped with a thermometer, stirrer, and condenser. Heat and stir in an oil bath at 80℃ for 20min. Then, add 8% of the pre-emulsion to the flask all at once. Dissolve 0.03g of sodium persulfate in 0.9g of deionized water and add it to the flask. After the reaction system shows blue light, keep it warm for 20min. Add the remaining 92% of the pre-emulsion dropwise over 3h using a constant pressure funnel, while simultaneously adding 3g of a deionized water solution containing 0.1g of sodium persulfate. After all the addition is complete, keep it warm for one hour. After cooling to room temperature, adjust the pH of the solution to 7-9 with ammonia water to obtain the aqueous cationic photolytic adhesive pressure-sensitive latex.

[0053] (3) Place the corona-treated PET polyester film on a coating plate with the corona-treated side facing up. Take a certain amount of the water-based cationic photolytic adhesive pressure-sensitive latex and add 2% of the total mass of the latex as cationic photoinitiator 4-(phenylthio)phenyldiphenylthionium hexafluorophosphate. After mixing evenly, use a wire bar coater to evenly coat a certain amount of the latex onto the surface of the PET film. Place the film in an oven at 80°C and bake for 20 minutes. After baking, take it out to obtain a dry film of 15-20 μm. Use a conveyor belt UV curing machine to irradiate with ultraviolet light to obtain the pressure-sensitive adhesive.

[0054] Example 7

[0055] The only difference between Example 7 and Example 1 is that the emulsifier SR-10 is used instead of COPS-1 by mass.

[0056] Example 8

[0057] Example 8 is similar to Example 1 except that the emulsifier is replaced by polyoxyethylene laurate-6 ester instead of COPS-1.

[0058] Comparative Example 1

[0059] The only 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.

[0060] Comparative Example 2

[0061] The only difference between Comparative Example 2 and Example 1 is that the amount of modified monomer 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate added is 2.3g.

[0062] Comparative Example 3

[0063] The only difference between Comparative Example 3 and Example 1 is that both emulsifiers SR-10 and COPS-1 are replaced with sodium lauryl sulfate.

[0064] Comparative Example 4

[0065] The only difference between Comparative Example 4 and Example 1 is that the modified monomer is replaced by an equimolar amount of 4-acryloylmorpholine instead of 7-oxabicyclo[4.1.0]heptane-3-methyl methacrylate.

[0066] test

[0067] 1. Ultraviolet light energy control

[0068] The pressure-sensitive adhesive is irradiated with different energies by adjusting the speed of the conveyor belt of the tracked UV curing machine (RW-UVA302-30, Shenzhen Runwo Electromechanical Co., Ltd.). The UV irradiation energy is detected and controlled by a UV energy meter (UV-150, German UV-DESGN).

[0069] 2. Peel strength test

[0070] The test was conducted according to GB / T 2792-2014 standard. A universal testing machine (KJ-1065, Dongguan Kejian Instrument Co., Ltd.) was used to measure the peel 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°.

[0071] 3. Water-resistant whitening performance test

[0072] Immerse the pressure-sensitive adhesive sample in tap water at room temperature (approximately 25°C), with the adhesive side facing down. Observe the whitening of the pressure-sensitive adhesive film after 24 hours. The test results are expressed as 1-5, where 1 indicates no whitening and 5 indicates complete whitening.

[0073] 4. Wafer Residue Test

[0074] The pressure-sensitive adhesive sample was adhered to the wafer, and then peeled off using a universal testing machine (KJ-1065, Dongguan Kejian Instrument Co., Ltd.). Finally, a 500x magnifying glass was used to observe whether there was any residual adhesive on the wafer.

[0075] Table 1 shows the peeling performance and water-whitening resistance of the water-based cationic photolytic pressure-sensitive adhesives prepared in Examples 1-8 and Comparative Examples 1-4 of this invention.

[0076] Table 1

[0077]

[0078]

[0079] As can be seen from the test results in the table above, the photoadhesive pressure-sensitive adhesive prepared according to the present invention has the characteristics of high initial tack, high viscosity and excellent water whitening resistance, and the peeling force decreases significantly after UV irradiation, showing good de-adhesion effect.

[0080] 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 of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. A water-based cationic photolytic pressure-sensitive adhesive, characterized in that, Composed of a cationic initiator and a photolytically degradable pressure-sensitive adhesive emulsion, the preparation method of the photolytically degradable pressure-sensitive adhesive emulsion includes the following steps: Provide soft monomers, hard monomers, functional monomers, and modified monomers in predetermined weight parts, wherein, by weight parts, there are 5-15 parts of hard monomers, 40-60 parts of soft monomers, 2-5 parts of functional monomers, and 0.1-2 parts of modified monomers. Preparation of preemulsion: Mix 2-4 parts by weight of emulsifier 1 and 10-30 parts by weight of water, add weighed soft monomers, hard monomers, functional monomers and modified monomers and mix to obtain preemulsion; Preparation of photolytic adhesive pressure-sensitive latex: Mix 0.2-1 parts by weight of emulsifier 2 and 30-70 parts by weight of water evenly, add 5-10% of the pre-emulsion based on the total mass of the pre-emulsion, add the first initiator aqueous solution, polymerize under the action of the first initiator, after the reaction system shows blue light, keep the reaction at the temperature for 10-40 min, then add the remaining pre-emulsion and the second initiator aqueous solution dropwise, continue the reaction for 0.5-1.5 h, after the reaction is completed, adjust the pH value to 7-9 to obtain the photolytic adhesive pressure-sensitive latex; The emulsifier 2 is selected from at least one of sodium allyl sulfonate, ammonium allyl oxyethylene ether sulfate, and polyoxyethylene fatty acid ester; the modified monomer includes methyl 7-oxabicyclo[4.1.0]heptane-3-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; Emulsifier 1 is a mixture of sodium 3-allyloxy-1-hydroxy-propanesulfonate and ammonium allyloxypolyoxyethylene ether sulfate, with a mass ratio of (1.2 to 1.5):

1.

2. The water-based cationic photolytic pressure-sensitive adhesive according to claim 1, characterized in that, The hard monomers include methyl methacrylate and / or styrene; the soft monomers include one or more of ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and octyl acrylate; the functional monomers include one or more of methacrylic acid, acrylic acid, acrylamide, and N-hydroxymethylacrylamide.

3. The water-based cationic photolytic pressure-sensitive adhesive according to claim 1, characterized in that, The first initiator and the second initiator are selected from one or more initiators selected from azobisisobutyranin hydrochloride, azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, tert-butyl hydroperoxide, methyl ethyl ketone peroxide, sodium persulfate or ammonium persulfate.

4. The water-based cationic photolytic pressure-sensitive adhesive according to claim 1, characterized in that, The specific steps of adding the weighed soft monomers, hard monomers, functional monomers, and modified monomers are as follows: add the weighed soft monomers and hard monomers, emulsify them thoroughly, and then add the functional monomers and modified monomers for further mixing.

5. The water-based cationic photolytic pressure-sensitive adhesive according to claim 1, characterized in that, In the step of preparing the photolytic adhesive pressure-sensitive latex, the remaining pre-emulsion and the aqueous solution of the second initiator are added dropwise over 2-4 hours. After the addition is complete, the reaction continues for 0.5-1.5 hours. The reaction system is then cooled to 20-35°C, and the pH is adjusted to 7-9 to obtain the photolytic adhesive pressure-sensitive latex.

6. The water-based cationic photolytic pressure-sensitive adhesive according to claim 1, characterized in that, The cationic initiator is selected from one or more of diaryliodonium hexafluorophosphate, diaryliodonium hexafluoroantimonate, triarylthionium hexafluorophosphate, and triarylthionium hexafluoroantimonate.

7. The water-based cationic photolytic pressure-sensitive adhesive according to claim 1, characterized in that, The amount of the cationic initiator is 0.5-3% of the total mass of the pressure-sensitive adhesive latex.

Images