Modified MQ type silicon resin as well as preparation method and application thereof

Abstract

The invention discloses modified MQ type silicon resin and a preparation method and application thereof, and belongs to the field of organic silicon resin, a porous adsorption framework containing disulfide bonds is loaded on the surface of benzotriazole modified silicon dioxide, the silicon dioxide has excellent moisture-proof capacity, and benzotriazole groups grafted on the surface can absorb ultraviolet light, so that the moisture-proof performance of the silicon dioxide is improved, and the service life of the silicon dioxide is prolonged. Ultraviolet light energy is converted into heat energy, the surface-loaded porous adsorption framework containing disulfide bonds reversibly breaks and recombines under high-temperature and humid conditions, a weak interface layer caused by migration of silicon to the surface can be repaired, and when the temperature of the pressure-sensitive adhesive rises due to heat energy and ultraviolet irradiation, the disulfide bonds can be promoted to break by temperature rise, so that the pressure-sensitive adhesive can be used for repairing the surface of the pressure-sensitive adhesive. The silicon migration degree caused by high temperature, high humidity and ultraviolet irradiation can be avoided, so that the bonding strength of the pressure-sensitive adhesive and an adhered object is improved.

Description

Technical Field

[0001] The present invention belongs to the field of silicone resins, and specifically relates to a modified MQ silicone resin, a preparation method thereof, and an application thereof. Background Art

[0002] MQ silicone resin is a type of organic resin with a three-dimensional spatial structure composed of monofunctional siloxane linkages and tetrafunctional siloxane linkages; MQ silicone resin has good adhesion, heat resistance, weather resistance, chemical resistance, and film-forming properties, and has good applications in many fields, especially in pressure-sensitive adhesives, release agents, cosmetics, pressure-sensitive adhesives, etc. Organosilicon pressure-sensitive adhesives are mainly composed of silicone rubber raw rubber, MQ silicone resin, and a solvent mixed in a certain proportion. The silicone rubber can increase the fluidity of the pressure-sensitive adhesive, thereby increasing the interfacial adhesion force and having strong initial tack. As the main body of cross-linking and curing, the MQ silicone resin, as a reinforcing agent, has a great influence on the adhesive performance of the pressure-sensitive adhesive. By increasing the viscosity and reinforcement of the MQ silicone resin, the adhesive strength of the organosilicon pressure-sensitive adhesive can be significantly improved.

[0003] Chinese Patent Publication No. CN118085290B discloses a preparation method and application of an MQ resin. The MQ resin prepared in the present invention combines the compounding properties of conventional high-vinyl-content MQ resin and methyl MQ resin, and prepares a low-vinyl-content and low-hydroxyl-value modified MQ resin. Functional monomers (such as epoxy groups, alkoxy groups, acetoxy groups, amino groups, etc.) are introduced onto the low-vinyl MQ resin to replace the anchoring agent in the prior art. On the basis of satisfying the improvement of the substrate adhesion, the problem of silicon migration during the long-term use of the pressure-sensitive adhesive is solved. However, in this scheme, epoxy groups and acetoxy groups are prone to water absorption and hydrolysis. Under high-temperature and high-humidity conditions, after long-term contact with water molecules in the air, the silicon-oxygen bond will be attacked by water molecules and slowly decomposed, and the small molecules generated by the decomposition will aggravate the migration degree and reduce the bonding strength with the adherend. Summary of the Invention

[0004] The purpose of the present invention is to provide a modified MQ silicone resin, a preparation method thereof, and an application thereof. By loading a porous adsorption skeleton containing disulfide bonds on the surface of silica modified by benzotriazole, the silica has excellent moisture-proof ability. The surface-grafted benzotriazole groups can convert ultraviolet light energy into heat energy after absorbing ultraviolet light. The surface-loaded porous adsorption skeleton containing disulfide bonds can undergo reversible cleavage and recombination under high-temperature and humid conditions, and can repair the weak interfacial layer caused by silicon migration to the surface. When the temperature of the pressure-sensitive adhesive rises due to heat energy and ultraviolet light irradiation, it promotes the cleavage of disulfide bonds, and can avoid the degree of silicon migration caused by high-temperature, high-humidity, and ultraviolet light irradiation conditions, thereby improving the bonding strength between the pressure-sensitive adhesive and the adherend.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A preparation method of a modified MQ silicone resin, which is prepared through the following steps:

[0007] Step 1: A porous adsorption skeleton is obtained by hydrolysis and condensation of a prepolymer containing disulfide bonds and γ-aminopropyltriethoxysilane in ethanol; benzotriazole-modified silica, the porous adsorption skeleton, and N,N-dimethylformamide are added to a reaction kettle, and stirred at 50-60 °C and 500-600 r / min for 2-4 h, then filtered, and the filter cake is washed 2-3 times with deionized water and absolute ethanol respectively, and dried in vacuum to obtain functionalized silica microspheres.

[0008] Step 2: Toluene, deionized water, and concentrated hydrochloric acid with a mass fraction of 36-38% are added to a reaction kettle, and stirred at 40-50 °C and 500-600 r / min for 10-12 min, then tetraethyl orthosilicate, hexamethyldisiloxane, and tetramethyldivinyldisiloxane are added, and the reaction continues for 2-3 h, then sodium hydroxide with a concentration of 0.1 mo / L is added to adjust the pH value to 8-9, then trimethylethoxysilane and functionalized silica microspheres are added, heated to 100-110 °C, and the reaction continues for 2-3 h, 0.1 mo / L hydrochloric acid is added to neutralize the pH value to 7, filtered, and the filter cake is washed with deionized water and absolute ethanol until the last washing liquid is neutral, and dried in vacuum to obtain a modified MQ silicone resin.

[0009] Further, in Step 1, the dosage ratio of benzotriazole-modified silica, the porous adsorption skeleton, and N,N-dimethylformamide is 50-60 g: 30-40 g: 800-900 mL.

[0010] Further, in Step 2, the dosage ratio of toluene, deionized water, concentrated hydrochloric acid, tetraethyl orthosilicate, hexamethyldisiloxane, tetramethyldivinyldisiloxane, trimethylethoxysilane, and functionalized silica microspheres is 500-600 mL: 800-900 mL: 20-30 mL: 300-400 g: 200-220 g: 50-60 g: 20-30 g: 20-30 g.

[0011] Further, the benzotriazole-modified silica in Step 1 is prepared through the following steps:

[0012] Acid chloride-modified silica and tetrahydrofuran are added to a reaction kettle, and stirred at 50-60 °C and 500-600 r / min for 10-12 min, then modified benzotriazole and triethylamine are added, and stirring continues for 5-6 h, filtered, and the filter cake is washed 2-3 times with saturated sodium bicarbonate solution and absolute ethanol respectively, and dried in vacuum at 60-80 °C for 1-2 h to obtain benzotriazole-modified silica.

[0013] Further, the dosage ratio of silicon dioxide acyl chloride, tetrahydrofuran, modified benzotriazole, and triethylamine is 18 - 25 g : 500 - 600 mL : 20 - 30 g : 3 - 4 mL.

[0014] Further, the modified benzotriazole is prepared through the following steps:

[0015] Add 2-(2,4-dihydroxyphenyl)-2H-benzotriazole, toluene, and benzoyl chloride into the reaction kettle according to the dosage ratio of 30 - 40 g : 100 - 200 mL : 12 - 14 mL, stir at 90 - 100 °C and 500 - 600 r / min for 6 - 7 h, cool naturally, filter, wash the filter cake with ionized water and absolute ethanol respectively for 2 - 3 times, and vacuum dry at 60 - 80 °C for 1 - 2 h to obtain the modified benzotriazole.

[0016] Further, the silicon dioxide acyl chloride is prepared through the following steps:

[0017] Add dichloromethane and 3,3'-(ethene-1,2-diyl) dibenzoyl chloride into the reaction kettle, stir at 20 - 25 °C and 500 - 600 r / min for 10 - 12 min, then add mesoporous silicon dioxide and triethylamine, heat to 50 - 60 °C, continue stirring for 3 - 4 h, carry out suction filtration, wash the filter cake with dichloromethane and deionized water respectively for 2 - 3 times, and vacuum dry to obtain the silicon dioxide acyl chloride.

[0018] Further, the dosage ratio of dichloromethane, 3,3'-(ethene-1,2-diyl) dibenzoyl chloride, mesoporous silicon dioxide, and triethylamine is 800 - 900 mL : 70 - 80 g : 80 - 90 g : 1 - 2 mL.

[0019] Further, the porous adsorption framework in step two is prepared through the following steps:

[0020] Add the prepolymer, γ-aminopropyltriethoxysilane, hydrochloric acid solution with a concentration of 1 moL / L, ammonium fluoride solution with a mass fraction of 50 - 60%, and 500 - 600 mL of absolute ethanol, continue stirring and reacting for 10 - 12 min, add ferric nitrate nonahydrate and toluene into the reaction kettle, carry out ultrasonic dispersion for 30 - 40 min, continue stirring and reacting for 14 - 16 h, filter, wash the filter cake with ionized water and absolute ethanol respectively for 2 - 3 times, and vacuum dry to obtain the porous adsorption framework.

[0021] Further, the dosage ratio of the prepolymer, γ-aminopropyltriethoxysilane, hydrochloric acid solution, ammonium fluoride solution, absolute ethanol, ferric nitrate nonahydrate, and toluene is 50 - 60 g : 45 - 55 g : 2 - 2.5 mL : 3 - 5 mL : 15 - 20 g : 150 - 200 mL.

[0022] Further, the prepolymer is prepared by the following steps:

[0023] Cystamine, N-hydroxymethylacrylamide and deionized water are added to a reaction kettle according to a dosage ratio of 15-20 g: 20-25 g: 400-500 mL, stirred at 70-75 °C and 500-600 r / min for 1-2 h, filtered, and the filter cake is washed 2-3 times with ionized water and absolute ethanol respectively, and vacuum dried at 60-80 °C for 1-2 h to obtain a functional compound; 3-glycidyltrimethoxysilane, ethylenediamine, the functional compound and deionized water are added to a reaction kettle according to a dosage ratio of 80-90 mL: 2-3 mL: 50-60 g: 400-500 mL, heated to 80-90 °C under a nitrogen atmosphere, and stirred at 500-600 r / min for 1-2 h, filtered, and the filter cake is washed 2-3 times with ionized water and absolute ethanol respectively, and vacuum dried to obtain a prepolymer.

[0024] The present invention also provides an application of the modified MQ-type silicone resin in a pressure-sensitive adhesive.

[0025] Advantages of the present invention:

[0026] 1. The modified MQ-type silicone resin prepared by the present invention has a porous adsorption skeleton containing disulfide bonds loaded on the surface of benzotriazole-modified silica to obtain functionalized silica microspheres. Using the functionalized silica microspheres as fillers, the modified MQ-type silicone resin has excellent moisture-proof, anti-aging and ultraviolet radiation resistance capabilities, and has small silicon migration and will not crack under high temperature, high humidity and ultraviolet radiation.

[0027] 2. For the porous adsorption skeleton of the present invention, two primary amino groups of cystamine are used as nucleophiles to attack the unsaturated double bond of N-hydroxymethylacrylamide to undergo a Michael addition reaction, thereby obtaining a functional compound. The hydroxyl groups on the surface of the functional compound and the epoxy groups in 3-glycidyltrimethoxysilane are ring-opened under the action of ethylenediamine to obtain a prepolymer containing disulfide bonds. The prepolymer contains silane bonds and a porous adsorption skeleton obtained by hydrolysis and condensation of γ-aminopropyltriethoxysilane. The porous adsorption skeleton can increase the peel strength of the pressure-sensitive adhesive, and the surface roughness and porosity can increase the adsorption of silicon small molecules generated by silicon migration; the disulfide bonds undergo reversible cleavage and recombination under high temperature and humid conditions, endowing the material with self-healing ability to repair microcracks caused by silicon small molecule migration and avoiding the formation of a weak interface layer caused by migration to the surface, which can increase the effective contact area between the pressure-sensitive adhesive and the adherend and improve the adhesion.

[0028] 3. The benzotriazole-modified silica of the present invention is obtained by acyl chlorinating silica and reacting the acyl chloride group with the hydroxyl group in the modified benzotriazole to obtain benzotriazole-modified silica. After absorbing ultraviolet light, the intramolecular hydrogen bond of benzotriazole is broken, and the high-energy ultraviolet light energy can be converted into heat energy for corresponding energy conversion, and the energy of ultraviolet light is released in the form of harmless low-radiation heat energy. When the heat energy and the temperature rise of the pressure-sensitive adhesive caused by ultraviolet irradiation, the temperature rise can promote the cleavage of disulfide bonds and promote the repair of the material, avoiding the shedding of the pressure-sensitive adhesive caused by silicon migration under high temperature and high humidity for a long time. Detailed implementation mode

[0029] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0030] Example 1: A preparation method of a modified MQ-type silicone resin is prepared by the following steps:

[0031] S1: Add 15 g of cystamine, 20 g of N-hydroxymethylacrylamide and 400 mL of deionized water into a reaction kettle, stir at 70 °C and 500 r / min for 1 h, filter, wash the filter cake with deionized water and absolute ethanol twice respectively, and vacuum dry at 60 °C for 1 h to obtain a functional compound; Add 80 mL of 3-glycidyltrimethoxysilane, 2 mL of ethylenediamine, 50 g of the functional compound and 400 mL of deionized water into the reaction kettle, heat to 80 °C under a nitrogen atmosphere, stir at 500 r / min for 1 h, filter, wash the filter cake with deionized water and absolute ethanol twice respectively, and vacuum dry at 60 °C for 1 h to obtain a prepolymer.

[0032] The two primary amino groups of cystamine act as nucleophiles to attack the unsaturated double bond of N-hydroxymethylacrylamide to undergo a Michael addition reaction, thereby obtaining a functional compound. The hydroxyl group on the surface of the functional compound and the epoxy group in 3-glycidyltrimethoxysilane are ring-opened under the action of ethylenediamine to obtain a prepolymer containing disulfide bonds.

[0033] S2: Add 80 mL of 3-glycidyltrimethoxysilane, 2 mL of ethylenediamine, 50 g of functional compound, and 400 mL of deionized water into a reaction kettle. Under a nitrogen atmosphere, heat to 80 °C and stir for 1 h at 500 r / min. Filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 60 °C for 1 h to obtain a prepolymer. Add 50 g of the prepolymer, 45 g of γ-aminopropyltriethoxysilane, 2 mL of hydrochloric acid solution with a concentration of 1 moL / L, 3 mL of ammonium fluoride solution with a mass fraction of 50%, and 500 mL of anhydrous ethanol, and continue to stir and react for 10 min. Add 15 g of ferric nitrate nonahydrate and 150 mL of toluene into the reaction kettle, disperse ultrasonically for 30 min, continue to stir and react for 14 h, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 60 °C for 1 h to obtain a porous adsorption framework.

[0034] The prepolymer and γ-aminopropyltriethoxysilane hydrolyze into silanols (-Si-OH) in ethanol, and the silanols condense with each other to obtain a porous adsorption framework containing disulfide bonds. The porous adsorption framework contains disulfide bonds, which undergo reversible cleavage and recombination under high-temperature and humid conditions, endowing the material with self-healing ability to repair microcracks caused by the escape of small molecules, indirectly reducing the migration channels, and avoiding the weak interface layer caused by low-molecular-weight silicon compounds migrating to the surface. The weak interface layer can reduce the effective contact area between the pressure-sensitive adhesive and the adherend, resulting in a decrease in adhesive force.

[0035] S3: Add 800 mL of dichloromethane and 70 g of 3,3'-(ethene-1,2-diyl)dibenzoyl chloride into a reaction kettle, stir at 20 °C and 500 r / min for 10 min, then add 80 g of mesoporous silica and 1 mL of triethylamine, heat to 50 °C, and continue to stir for 3 h. Filter by suction, wash the filter cake twice with dichloromethane and deionized water respectively, and dry it in vacuum at 60 °C for 1 h to obtain acyl chloride-functionalized silica.

[0036] The acyl chloride groups on 3,3'-(ethene-1,2-diyl)dibenzoyl chloride react with the hydroxyl groups on the surface of mesoporous silica. 3,3'-(ethene-1,2-diyl)dibenzoyl chloride is a substance containing two terminal acyl chloride groups, and acyl chloride-functionalized silica is obtained.

[0037] S4: Add 30 g of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole, 100 mL of toluene, and 12 mL of benzoyl chloride into a reaction kettle, stir at 90 °C and 500 r / min for 6 h, cool naturally, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 60 °C for 1 h to obtain modified benzotriazole.

[0038] S5: Add 18 g of silica dioxide dichloride and 500 mL of tetrahydrofuran into a reaction kettle, stir for 10 min under the conditions of 50 °C and 500 r / min, then add 20 g of modified benzotriazole and 3 mL of triethylamine, continue to stir for 5 h, filter, wash the filter cake twice with saturated sodium bicarbonate solution and anhydrous ethanol respectively, and dry it in vacuum at 60 °C for 1 h to obtain benzotriazole-modified silica dioxide.

[0039] S6: Add 50 g of benzotriazole-modified silica dioxide, 30 g of porous adsorption framework and 800 mL of N,N-dimethylformamide into a reaction kettle, stir for 2 h under the conditions of 50 °C and 500 r / min. After the reaction is completed, carry out suction filtration, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 60 °C for 1 h to obtain functionalized silica microspheres.

[0040] The structural formula of silica dioxide dichloride contains unreacted acyl chloride groups at the other end, which can react with the hydroxyl groups in the modified benzotriazole to obtain benzotriazole-modified silica dioxide; the structural formula of benzotriazole-modified silica dioxide contains carboxyl groups, which can react with the amino groups in the structural formula of the porous adsorption framework, enabling the porous adsorption framework to be uniformly loaded on the surface of mesoporous silica.

[0041] After benzotriazole absorbs ultraviolet light, the intramolecular hydrogen bond is broken, which can convert high-energy ultraviolet light energy into heat energy, perform corresponding energy conversion, and release the energy of ultraviolet light in the form of harmless low-radiation heat energy. When the heat energy and the temperature rise of the pressure-sensitive adhesive caused by ultraviolet irradiation, the temperature rise can promote the cleavage of disulfide bonds, promote the repair of the material, and avoid the peeling of the pressure-sensitive adhesive caused by silicon migration under high temperature and high humidity for a long time.

[0042] S7: Add 500 mL of toluene, 800 mL of deionized water, and 20 mL of concentrated hydrochloric acid with a mass fraction of 36% into a reaction kettle, stir for 10 min under the conditions of 40 °C and 500 r / min, then add 300 g of tetraethyl orthosilicate, 200 g of hexamethyldisiloxane and 50 g of tetramethyldivinyldisiloxane, continue the reaction for 2 h, then add sodium hydroxide with a concentration of 0.1 mo / L to adjust the pH value to 8, add 20 g of trimethylethoxysilane and 20 g of functionalized silica microspheres, heat to 100 °C, continue the reaction for 2 h, add 0.1 mo / L hydrochloric acid to neutralize the pH value to 7, filter, wash the filter cake with deionized water and anhydrous ethanol until the last washing liquid is neutral, and dry it in vacuum at 60 °C for 1 h to obtain a modified MQ-type silicone resin.

[0043] Example 2: A preparation method of a modified MQ-type silicone resin is prepared through the following steps:

[0044] S1: Add 17.5 g of cystamine, 22.5 g of N-hydroxymethylacrylamide, and 450 mL of deionized water into a reaction kettle. Stir for 1.5 h at 72.5 °C and 550 r / min. Filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 70 °C for 1.5 h to obtain a functional compound. Add 85 mL of 3-glycidyltrimethoxysilane, 2.5 mL of ethylenediamine, 55 g of the functional compound, and 450 mL of deionized water into the reaction kettle. Under a nitrogen atmosphere, heat to 85 °C and stir for 1.5 h at 550 r / min. Filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 70 °C for 1.5 h to obtain a prepolymer.

[0045] S2: Add 55 g of the prepolymer, 50 g of γ-aminopropyltriethoxysilane, 2.25 mL of a hydrochloric acid solution with a concentration of 1 moL / L, 4 mL of an ammonium fluoride solution with a mass fraction of 55%, and 550 mL of anhydrous ethanol, and continue stirring and reacting for 11 min. Add 17.5 g of ferric nitrate nonahydrate and 175 mL of toluene into the reaction kettle, ultrasonically disperse for 35 min, continue stirring and reacting for 15 h, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 70 °C for 1.5 h to obtain a porous adsorption framework.

[0046] S3: Add 850 mL of dichloromethane and 75 g of 3,3'-(ethene-1,2-diyl)dibenzoyl chloride into a reaction kettle. Stir for 11 min at 22.5 °C and 550 r / min, then add 85 g of mesoporous silica and 1.5 mL of triethylamine, heat to 55 °C, and continue stirring for 3.5 h. Carry out suction filtration, wash the filter cake twice with dichloromethane and deionized water respectively, and dry it in vacuum at 70 °C for 1.5 h to obtain acyl chloride-functionalized silica.

[0047] S4: Add 35 g of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole, 150 mL of toluene, and 13 mL of benzoyl chloride into a reaction kettle. Stir for 6.5 h at 95 °C and 550 r / min, cool naturally, filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 70 °C for 1.5 h to obtain modified benzotriazole.

[0048] S5: Add 21.5 g of acyl chloride-functionalized silica and 550 mL of tetrahydrofuran into a reaction kettle. Stir for 11 min at 55 °C and 550 r / min, then add 25 g of modified benzotriazole and 3.5 mL of triethylamine, continue stirring for 5.5 h, filter, wash the filter cake twice with saturated sodium bicarbonate solution and anhydrous ethanol respectively, and dry it in vacuum at 70 °C for 1.5 h to obtain benzotriazole-modified silica.

[0049] S6: Add 55 g of benzotriazole-modified silica, 35 g of porous adsorption framework, and 850 mL of N,N-dimethylformamide into a reaction kettle, stir for 3 h under the conditions of 55 °C and 550 r / min. After the reaction is completed, perform suction filtration, wash the filter cake twice with deionized water and absolute ethanol respectively, and dry it in vacuum at 70 °C for 1.5 h to obtain functionalized silica microspheres.

[0050] S7: Add 550 mL of toluene, 850 mL of deionized water, and 25 mL of concentrated hydrochloric acid with a mass fraction of 37% into a reaction kettle, stir for 11 min under the conditions of 45 °C and 550 r / min, then add 350 g of tetraethyl orthosilicate, 210 g of hexamethyldisiloxane, and 55 g of tetramethyldivinyldisiloxane, continue the reaction for 2.5 h, then add sodium hydroxide with a concentration of 0.1 mo / L to adjust the pH value to 8.5, add 25 g of trimethylethoxysilane and 25 g of functionalized silica microspheres, heat to 105 °C, continue the reaction for 2.5 h, add 0.1 mo / L hydrochloric acid to neutralize the pH value to 7, filter, wash the filter cake with deionized water and absolute ethanol until the last washing liquid is neutral, and dry it in vacuum at 70 °C for 1.2 h to obtain a modified MQ-type silicone resin.

[0051] Example 3: A preparation method of a modified MQ-type silicone resin is prepared through the following steps:

[0052] S1: Add 20 g of cystamine, 25 g of N-hydroxymethylacrylamide, and 500 mL into a reaction kettle, stir for 2 h under the conditions of 75 °C and 600 r / min, filter, wash the filter cake three times with deionized water and absolute ethanol respectively, and dry it in vacuum at 80 °C for 2 h to obtain a functional compound; add 90 mL of 3-glycidyltrimethoxysilane, 3 mL of ethylenediamine, 60 g of the functional compound, and 500 mL of deionized water into a reaction kettle, heat to 90 °C under a nitrogen atmosphere, stir for 2 h under the conditions of 600 r / min, filter, wash the filter cake three times with deionized water and absolute ethanol respectively, and dry it in vacuum at 80 °C for 2 h to obtain a prepolymer.

[0053] S2: Add 60 g of the prepolymer, 55 g of γ-aminopropyltriethoxysilane, 2.5 mL of hydrochloric acid solution with a concentration of 1 moL / L, 5 mL of ammonium fluoride solution with a mass fraction of 60%, and 600 mL of absolute ethanol, continue stirring and reacting for 12 min, add 20 g of ferric nitrate nonahydrate and 200 mL of toluene into the reaction kettle, perform ultrasonic dispersion for 40 min, continue stirring and reacting for 16 h, filter, wash the filter cake three times with deionized water and absolute ethanol respectively, and dry it in vacuum at 80 °C for 2 h to obtain a porous adsorption framework.

[0054] S3: Add 900 mL of dichloromethane and 80 g of 3,3'-(ethene-1,2-diyl) dibenzoyl chloride into a reaction kettle, stir for 12 min under the conditions of 25 °C and 600 r / min, then add 90 g of mesoporous silica and 2 mL of triethylamine, heat to 60 °C, continue to stir for 4 h, perform suction filtration, wash the filter cake 3 times with dichloromethane and deionized water respectively, and dry in vacuum at 80 °C for 2 h to obtain acyl chloride silica.

[0055] S4: Add 40 g of 2-(2,4-dihydroxyphenyl)-2H-benzotriazole, 200 mL of toluene and 14 mL of benzoyl chloride into a reaction kettle, stir for 7 h under the conditions of 100 °C and 600 r / min, cool naturally, filter, wash the filter cake 3 times with ionized water and absolute ethanol respectively, and dry in vacuum at 80 °C for 2 h to obtain modified benzotriazole.

[0056] S5: Add 25 g of acyl chloride silica and 600 mL of tetrahydrofuran into a reaction kettle, stir for 12 min under the conditions of 60 °C and 600 r / min, then add 30 g of modified benzotriazole and 4 mL of triethylamine, continue to stir for 6 h, filter, wash the filter cake 3 times with saturated sodium bicarbonate solution and absolute ethanol respectively, and dry in vacuum at 80 °C for 2 h to obtain benzotriazole modified silica.

[0057] S6: Add 60 g of benzotriazole modified silica, 40 g of porous adsorption framework and 900 mL of N,N-dimethylformamide into a reaction kettle, stir for 4 h under the conditions of 60 °C and 600 r / min. After the reaction is completed, perform suction filtration, wash the filter cake 3 times with ionized water and absolute ethanol respectively, and dry in vacuum at 80 °C for 2 h to obtain functionalized silica microspheres.

[0058] S7: Add 600 mL of toluene, 900 mL of deionized water, 30 mL of concentrated hydrochloric acid with a mass fraction of 38% into a reaction kettle, stir for 12 min under the conditions of 50 °C and 600 r / min, then add 400 g of tetraethyl orthosilicate, 220 g of hexamethyldisiloxane and 60 g of tetramethyldivinyldisiloxane, continue to react for 3 h, then add sodium hydroxide with a concentration of 0.1 mo / L to adjust the pH value to 9, add 30 g of trimethylethoxysilane and 30 g of functionalized silica microspheres, heat to 110 °C, continue to react for 3 h, add 0.1 mo / L hydrochloric acid to neutralize the pH value to 7, filter, wash the filter cake with ionized water and absolute ethanol until the last washing liquid is neutral, and dry in vacuum at 80 °C for 2 h to obtain a modified MQ-type silicone resin.

[0059] Comparative Example 1: On the basis of Example 3, replace the prepolymer in step S2 with 3-glycidyltrimethoxysilane with the same mass in step S1, and keep the other steps unchanged to prepare a modified MQ-type silicone resin.

[0060] Comparative Example 2: On the basis of Example 3, the benzotriazole-modified silica in step S6 was replaced with commercially available mesoporous silica powder of the same mass, and the remaining steps remained unchanged to prepare a modified MQ-type silicone resin.

[0061] Comparative Example 3: On the basis of Example 3, the porous adsorption framework in step S6 was replaced with the functional compound in step S1 of the same mass, and the remaining steps remained unchanged to prepare a modified MQ-type silicone resin.

[0062] The modified MQ-type silicone resins obtained in Examples 1 - 3 and Comparative Examples 1 - 3 were made into pressure-sensitive adhesives for performance testing: 40 g of the modified MQ-type silicone resin, 20 g of commercially available vinyl methyl silicone rubber, 60 g of xylene, 0.8 g of hydrogen-containing silicone oil, 0.6 g of commercially available anchoring agent, 0.1 g of ethynylcyclohexanol, and 0.4 g of platinum catalyst were stirred evenly to obtain a pressure-sensitive adhesive. The pressure-sensitive adhesive sample was evenly coated on the corona-treated PET film with a 70-μm coating rod, baked in an oven at 150°C for 2 minutes, and then cut into tapes and pasted on a steel plate to obtain test samples.

[0063] 1. Peel strength test: The test was carried out with reference to the standard of GB / T2792-2014, and the peel strength of the pressure-sensitive adhesive was tested with a tensile machine.

[0064] 2. Ultraviolet resistance test method: The test was carried out with reference to the standard of ISO4892-2. The test samples were placed in an environmental chamber for aging, and after observing for 1000 h, it was checked whether the adhesive layer cracked, and the peel strength on the steel plate was tested.

[0065] 3. Temperature and humidity aging and silicon migration test: The test samples were placed in a constant temperature and humidity chamber. After aging for 72 h at a temperature of 85°C and a humidity of 85%, the peel strength after aging was tested, and the pollution state of the steel plate surface was observed.

[0066] 4. Haze and transparency test method: With reference to the test method in the determination of light transmittance and haze of transparent plastics in GB / T2410-2008, at 170°C, the pressure-sensitive adhesive sample was coated on a 50-μm transparent PET film with a doctor blade coater, the thickness of the adhesive film was controlled to be 300 μm, and a 50-μm-thick PET film was attached to the surface. Then, the haze and transparency of the pressure-sensitive adhesive were tested with a haze meter.

[0067] Table 1 Test results of pressure-sensitive adhesive performance

[0068]

[0069]

[0070] As can be seen from Table 1, for the modified MQ-type silicone resins prepared in Examples 1 - 3 and Comparative Examples 1 - 3, the peel strength, the peel strength after ultraviolet aging, the peel strength after temperature and humidity aging, and the transmittance are significantly better than those of the comparative examples. The silicon migration and cracking conditions are also significantly better than those of the comparative examples, and the haze value is significantly lower than that of the comparative examples. This shows that the modified MQ-type silicone resin prepared by the present invention has excellent moisture-proof, aging-resistant, and ultraviolet-resistant abilities, and has little silicon migration and will not fall off and crack under high temperature, high humidity, and ultraviolet irradiation.

[0071] In Comparative Example 1, the prepolymer was replaced with 3-glycidyltrimethoxysilane. The two primary amino groups of cystamine served as nucleophiles to attack the unsaturated double bond of N-methylolacrylamide, and a Michael addition reaction occurred, thus obtaining a functional compound. The hydroxyl groups on the surface of the functional compound and the epoxy groups in 3-glycidyltrimethoxysilane underwent ring-opening under the action of ethylenediamine to obtain a prepolymer containing disulfide bonds. The disulfide bonds in the prepolymer underwent reversible cleavage and recombination under high-temperature and humid conditions, endowing the material with self-healing ability and avoiding the problem of reduced adhesion caused by the weak interfacial layer formed by low-molecular-weight silicon compounds migrating to the surface.

[0072] In Comparative Example 2, benzotriazole-modified silica was replaced with mesoporous silica powder. The benzotriazole-modified silica structural formula contains carboxyl groups, which can react with the amino groups in the porous adsorption framework structure, enabling the porous adsorption framework to be evenly loaded on the surface of mesoporous silica. The porous structure can increase the peel strength of the MQ-type silicone resin when prepared into a pressure-sensitive adhesive. After benzotriazole absorbs ultraviolet light, the intramolecular hydrogen bond is broken, and it can convert high-energy ultraviolet light energy into heat energy for corresponding energy conversion, releasing the ultraviolet light energy in the form of harmless low-radiation heat energy. When the heat energy and the temperature rise of the pressure-sensitive adhesive caused by ultraviolet irradiation occur, the temperature rise can promote the cleavage of disulfide bonds and promote the repair of the material, avoiding the peeling of the pressure-sensitive adhesive caused by silicon migration under high temperature and high humidity for a long time.

[0073] In Comparative Example 3, the porous adsorption framework was replaced with a functional compound. The porous adsorption framework contains disulfide bonds, endowing the material with self-healing ability. The porous structure can increase the adsorption effect of the disulfide bonds grafted on the surface on silicon small molecules, further avoiding the situation of silicon migration. The porous structure can increase the surface roughness of the pressure-sensitive adhesive, increase the adhesion of the pressure-sensitive adhesive to the adhered material, and the porous structure can disperse stress and avoid cracking.

[0074] It should be noted that in this article, terms such as "including", "comprising", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device.

[0075] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention.

Claims

1. A method for preparing a modified MQ type silicone resin, characterized in that: Prepared by the following steps: Step 1: A porous adsorption skeleton is obtained by hydrolyzing and condensing a prepolymer containing a disulfide bond with γ-aminopropyltriethoxysilane in ethanol; benzotriazole-modified silica, the porous adsorption skeleton and N,N-dimethylformamide are added to a reaction kettle, stirred at 50-60° C. and 500-600 r / min for 2-4 hours, filtered, washed, and vacuum dried to obtain functionalized silica microspheres; Step 2: Add toluene, deionized water, and 36-38wt% concentrated hydrochloric acid into a reactor, stir at 40-50°C and 500-600r / min for 10-12min, then add ethyl orthosilicate, hexamethyldisiloxane and tetramethyldivinyldisiloxane, continue to react for 2-3h, add 0.1mol / L sodium hydroxide, adjust the pH value to 8-9, then add trimethylethoxysilane and functionalized silica microspheres, heat to 100-110°C, continue to react for 2-3h, add 0.1mol / L hydrochloric acid to neutralize the pH value to 7, filter, wash, and vacuum dry to obtain a modified MQ silicone resin.

2. The method for preparing a modified MQ type silicone resin according to claim 1, characterized in that: The usage ratio of the benzotriazole-modified silica and the N,N-dimethylformamide of the porous adsorption framework in step 1 is 50-60 g: 30-40 g: 800-900 mL.

3. The method for preparing a modified MQ type silicone resin according to claim 1, characterized in that: The dosage ratio of toluene, deionized water, concentrated hydrochloric acid, ethyl orthosilicate, hexamethyldisiloxane, tetramethyldivinyldisiloxane, trimethylethoxysilane and functionalized silica microspheres in step 2 is 500-600 mL: 800-900 mL: 20-30 mL: 300-400 g: 200-220 g: 50-60 g: 20-30 g: 20-30 g.

4. The method for preparing a modified MQ type silicone resin according to claim 1, characterized in that: The benzotriazole-modified silica described in step 1 is prepared by the following steps: Add acyl chloride silicon dioxide and tetrahydrofuran into a reaction kettle, stir at 50-60°C and 500-600 r / min for 10-12 min, then add modified benzotriazole and triethylamine, continue stirring for 5-6 h, filter, wash, and vacuum dry to obtain benzotriazole-modified silicon dioxide; The usage ratio of the acyl chloride silicon dioxide, tetrahydrofuran, modified benzotriazole and triethylamine is 18-25 g: 500-600 mL: 20-30 g: 3-4 mL.

5. The method for preparing a modified MQ type silicone resin according to claim 4, characterized in that: The modified benzotriazole is prepared by the following steps: 2-(2,4-dihydroxyphenyl)-2H-benzotriazole, toluene and benzoyl chloride are added into a reaction kettle in a dosage ratio of 30-40 g: 100-200 mL: 12-14 mL, stirred at 90-100 ° C and 500-600 r / min for 6-7 hours, naturally cooled, filtered, washed and vacuum dried to obtain modified benzotriazole.

6. The method for preparing a modified MQ type silicone resin according to claim 4, characterized in that: The silicon dioxide acyl chloride is prepared by the following steps: Add dichloromethane and 3,3'-(ethylene-1,2-diyl)dibenzoyl chloride into a reaction kettle, stir at 20-25°C and 500-600r / min for 10-12min, then add mesoporous silica and triethylamine, heat to 50-60°C, continue stirring for 3-4h, filter, wash, and vacuum dry to obtain chlorinated silica; The usage ratio of the dichloromethane, 3,3'-(ethylene-1,2-diyl)dibenzoyl chloride, mesoporous silica and triethylamine is 800-900 mL: 70-80 g: 80-90 g: 1-2 mL.

7. The method for preparing a modified MQ type silicone resin according to claim 1, characterized in that: The porous adsorption framework in step 2 is prepared by the following steps: The prepolymer, γ-aminopropyltriethoxysilane, a hydrochloric acid solution with a concentration of 1 mol / L, a 50-60 wt% ammonium fluoride solution and 500-600 mL of anhydrous ethanol are added, and the reaction is continued with stirring for 10-12 minutes. Ferric nitrate nonahydrate and toluene are added into the reaction kettle, and ultrasonic dispersion is performed for 30-40 minutes. The reaction is continued with stirring for 14-16 hours, and the reaction is filtered, washed and vacuum dried to obtain a porous adsorption skeleton; The dosage ratio of the prepolymer, γ-aminopropyltriethoxysilane, hydrochloric acid solution, ammonium fluoride solution, anhydrous ethanol, ferric nitrate nonahydrate and toluene is 50-60g: 45-55g: 2-2.5mL: 3-5mL: 15-20g: 150-200mL.

8. The method for preparing a modified MQ type silicone resin according to claim 7, characterized in that: The prepolymer is prepared by the following steps: Cystamine, N-hydroxymethyl acrylamide and deionized water are added to a reactor in a dosage ratio of 15-20 g: 20-25 g: 400-500 mL, stirred at 70-75° C. and 500-600 r / min for 1-2 hours, filtered, washed, and vacuum dried to obtain a functional compound; 3-epoxypropyltrimethoxysilane, ethylenediamine, a functional compound and deionized water are added to a reactor in a dosage ratio of 80-90 mL: 2-3 mL: 50-60 g: 400-500 mL, heated to 80-90° C. under a nitrogen atmosphere, stirred at 500-600 r / min for 1-2 hours, filtered, washed, and vacuum dried to obtain a prepolymer.

9. A modified MQ type silicone resin, characterized in that: Prepared by the preparation method described in any one of claims 1 to 8.

10. Use of the modified MQ silicone resin according to claim 9 in pressure-sensitive adhesive.

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