Cysteine-enhanced uv-cured high peel force silicone pressure sensitive adhesive and preparation method

Abstract

The application discloses a cysteine-enhanced UV-cured high-peeling-force silicone pressure-sensitive adhesive and a preparation method thereof, and relates to a UV-cured high-peeling-force silicone pressure-sensitive adhesive and a preparation method thereof. In order to solve the problem that the traditional SPSA (silicone pressure sensitive adhesive) has a high flexibility of a polydimethylsiloxane (PDMS) main chain, a weak intermolecular force, low cohesion strength and low peeling force on a high surface energy base material, and is difficult to meet the high-performance bonding requirement, the pressure-sensitive adhesive comprises octamethylcyclotetrasiloxane, N-(beta-aminoethyl-gamma-aminopropyl)methyldimethoxysilane, deionized water, cysteine, an initiator, synthetic cysteine-modified aminopropyl silicone rubber, a vinyl MQ resin and an organic solvent, and belongs to the technical field of pressure-sensitive adhesives.

Description

Technical Field

[0001] This invention relates to a UV-curable high-peel-strength silicone pressure-sensitive adhesive and its preparation method, belonging to the field of pressure-sensitive adhesive technology. Background Technology

[0002] Silicone pressure-sensitive adhesives (SPSAs) hold a crucial position in extreme applications such as electronics, medical, and aerospace due to their excellent resistance to high and low temperatures, weather resistance, and bioinertness. However, the high flexibility and weak intermolecular forces of the polydimethylsiloxane (PDMS) backbone of traditional SPSAs result in low cohesive strength and peel strength to high surface energy substrates, making it difficult to meet the requirements of high-performance adhesion. To overcome this bottleneck, research has shifted its focus to chemical modification strategies. The core technology involves introducing highly polar functional groups such as amino groups (-NH2) into the silicone chain to significantly enhance hydrogen bonding and chemisorption with the substrate, while simultaneously designing and constructing precisely controllable crosslinking networks (e.g., using click chemistry) to effectively improve the cohesive strength of the adhesive. This side-group modification strategy is expected to overcome the bottleneck of insufficient peel strength in traditional SPSAs by optimizing intermolecular forces and constructing controllable crosslinking networks, ultimately producing novel silicone pressure-sensitive adhesives that combine high peel strength and excellent temperature resistance.

[0003] Patent CN115873542A, filed on January 4, 2023, discloses a high-peel-strength UV-curable pressure-sensitive adhesive with excellent reworkability and its preparation method. The raw materials for this UV-curable pressure-sensitive adhesive mainly include (meth)acrylate soft monomers, (meth)acrylate hard monomers, organosilicon macromonomers, photosensitive monomers, caprolactone, free radical thermal initiators, heat stabilizers, and catalysts. It exhibits excellent reworkability (i.e., peel-and-re-apply) in the initial application stage and high peel strength after 24 hours, making it difficult to peel off. Furthermore, this UV-curable pressure-sensitive adhesive has extremely low VOCs and is suitable for various technical fields such as food and medicine, construction and transportation, electronic products, and indoor daily necessities.

[0004] However, the aforementioned patented technology focuses too much on the reworkability of the pressure-sensitive adhesive in the early stages and does not improve the cohesive strength of the adhesive. Therefore, the peel force of the pressure-sensitive adhesive still cannot meet the requirements.

[0005] Therefore, we propose a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive to solve the above problems. Summary of the Invention

[0006] To address the problem that the high flexibility of the polydimethylsiloxane (PDMS) backbone of traditional SPSA results in weak intermolecular forces, leading to low cohesive strength and peel strength to high surface energy substrates, which makes it difficult to meet the requirements of high-performance bonding, this invention proposes a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive and its preparation method.

[0007] The technical solution adopted by the present invention to solve the above problems is as follows: The cysteine-reinforced UV-curable high-peel-strength silicone pressure-sensitive adhesive of the present invention comprises octamethylcyclotetrasiloxane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, deionized water, cysteine, initiator, synthesized cysteine-modified aminopropyl silicone rubber, vinyl MQ resin and organic solvent, wherein the mass fraction of octamethylcyclotetrasiloxane is 29.66 parts, the mass fraction of aminopropyl silane is 8.16~10.32 parts, the mass fraction of deionized water is 1.62 parts, the mass fraction of cysteine ​​is 3.26~6.53 parts, the mass fraction of alkali initiator is 0.12 parts, the mass fraction of cysteine-modified aminopropyl silicone rubber is 10 parts, the mass fraction of vinyl MQ resin is 4~8 parts, the mass fraction of photoinitiator is 0.14~0.18 parts, and the mass fraction of anhydrous ethanol organic solvent is 50 parts.

[0008] Furthermore, the aminopropylsilane is one or more of γ-aminopropylmethyldiethoxysilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, and 3-aminopropylmethyldimethoxysilane; Cysteine ​​is one or more of N-acetyl-L-cysteine, L-cysteine, and N-carbamoyl-L-cysteine.

[0009] Furthermore, the photoinitiator used for the UV curing reaction of cysteine-modified aminopropyl silicone rubber and vinyl MQ resin is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0010] Furthermore, the organic solvent is anhydrous ethanol.

[0011] The steps of the method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive according to the present invention include: Step 1: Weigh aminopropylsilane into a reaction vessel, add deionized water and hydrolyze at room temperature for 0.5 h, while stirring evenly and purging with nitrogen gas. Step 2: Heat the reaction vessel and perform vacuum distillation while stirring to remove excess water from the system. Step 3: Weigh octamethylcyclotetrasiloxane and alkaline gum into a reaction vessel, stir them evenly, and purge the system with nitrogen to remove oxygen. Step 4: Heat the reaction vessel, reflux it, and stir it evenly. After the polymerization reaction, remove the water generated during the polymerization process by reducing the pressure to increase the degree of polymerization. Continue the reaction for 2 hours. The molecular weight can be controlled by the polymerization time. Step 5: Heat the reaction vessel until the alkali gum is decomposed, and then cool it down to room temperature; Step 6: Dissolve cysteine ​​in anhydrous ethanol, add it to the reaction vessel after the reaction vessel has cooled to the target temperature, stir evenly, purge with nitrogen, react for 2 h, then remove the organic solvent by vacuum distillation, cool to room temperature, and discharge to obtain cysteine-modified aminopropyl silicone rubber. Step 7: Take the cysteine-modified aminopropyl silicone rubber and vinyl MQ resin prepared in Step 6 into a reaction vessel, add anhydrous ethanol as a solvent and adjust the viscosity of the system, and add 10 wt% photoinitiator 1173. Stir evenly, remove air bubbles, coat it on a PI film, place it in an oven for 5 min to evaporate the solvent, and then use a 365 nm ultraviolet light source to irradiate and perform a click reaction to cure, thus obtaining the cysteine-modified organosilicon pressure-sensitive adhesive.

[0012] Furthermore, in step 2, the reaction vessel is heated to 60 °C and distilled under reduced pressure for 1 h.

[0013] Furthermore, in step 4, the reaction vessel is heated to 115 °C, and after 1 hour of polymerization, the water generated during the polymerization process is removed by depressurization to increase the degree of polymerization.

[0014] Furthermore, in step 5, the reaction vessel is heated to 160 °C to decompose the alkali gel, and the reaction time is 0.5 h.

[0015] Furthermore, the decompression temperature in step 6 is 90 ℃.

[0016] Furthermore, in step 7, the temperature inside the drying oven is 80 ℃, and the click reaction curing time is 2 min.

[0017] The beneficial effects of this invention are as follows: This invention provides a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive. By introducing polar groups such as amino, carboxyl, and thiol groups into cysteine-modified aminopropyl silicone rubber, the adhesive properties of the aminopropyl silicone rubber can be improved simultaneously, effectively addressing the problem of poor adhesion performance of silicone pressure-sensitive adhesives. The viscosity of the silicone rubber can be adjusted by regulating the amount and type of cysteine ​​introduced, and the peel strength of the silicone pressure-sensitive adhesive can be adjusted by regulating the ratio of cysteine-modified aminopropyl silicone rubber to vinyl MQ resin.

[0018] Example Example 1: This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive. The monomer components selected are as follows: 0.05 mol (10.32 g) of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, 0.09 mol (1.62 g) of deionized water, 0.1 mol (29.66 g) of octamethylcyclotetrasiloxane, 0.12 g of alkali adhesive, 0.02 mol (3.26 g) of N-acetyl-L-cysteine, 4 g of vinyl MQ resin, 0.14 g of photoinitiator, and 50 ml of anhydrous ethanol.

[0019] This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive, comprising the following steps: (1) Weigh 10.32 g of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane into a reaction vessel, add 1.62 g of deionized water and hydrolyze at room temperature for 0.5 h, while stirring evenly and purging with nitrogen.

[0020] (2) Heat the reaction vessel to 60 °C and distill under reduced pressure for 1 h while stirring evenly to remove excess water from the system.

[0021] (3) Weigh 29.66 g of octamethylcyclotetrasiloxane and 0.12 g of alkaline gel into a reaction vessel, stir evenly, and purge the system with nitrogen to remove oxygen.

[0022] (4) Heat the reaction vessel to 115 °C, reflux and stir evenly. After 1 h of polymerization reaction, remove the water generated during the polymerization process under reduced pressure to increase the degree of polymerization, and continue the reaction for 2 h.

[0023] (5) Heat the reaction vessel to 160 °C to decompose the alkali gel, and the reaction time is 0.5 h. Then cool it down to room temperature.

[0024] (6) Dissolve 3.26 g of N-acetyl-L-cysteine ​​in 30 ml of anhydrous ethanol. After the reaction vessel is cooled to the target temperature, pour the solution into the reaction vessel, stir evenly, and purge with nitrogen gas. React for 2 h, then remove the organic solvent by vacuum distillation at 90 °C, cool to room temperature, and discharge the cysteine-modified aminopropyl silicone rubber, which is named L-NACSR.

[0025] (7) Weigh 10 g of the prepared L-NACSR and 4 g of vinyl MQ resin into a reaction vessel, add 20 ml of anhydrous ethanol as a solvent and adjust the viscosity of the system at the same time, add 0.14 g of photoinitiator 1173, stir evenly, remove bubbles and coat on PI film, place in an 80 ℃ oven for 5 min to evaporate the solvent, then use 365 nm ultraviolet light source to irradiate and perform click reaction curing for 2 min, and age at room temperature for 24 h to obtain cysteine ​​modified organosilicon pressure-sensitive adhesive.

[0026] Example 2: This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive. The monomer components selected are as follows: 0.05 mol (10.32 g) of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, 0.09 mol (1.62 g) of deionized water, 0.1 mol (29.66 g) of octamethylcyclotetrasiloxane, 0.12 g of alkali adhesive, 0.03 mol (4.90 g) of N-acetyl-L-cysteine, 6 g of vinyl MQ resin, 0.16 g of photoinitiator, and 50 ml of anhydrous ethanol.

[0027] This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive, comprising the following steps: (1) Weigh 10.32 g of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane into a reaction vessel, add 1.62 g of deionized water and hydrolyze at room temperature for 0.5 h, while stirring evenly and purging with nitrogen.

[0028] (2) Heat the reaction vessel to 60 °C and distill under reduced pressure for 1 h while stirring evenly to remove excess water from the system.

[0029] (3) Weigh 29.66 g of octamethylcyclotetrasiloxane and 0.12 g of alkaline gel into a reaction vessel, stir evenly, and purge the system with nitrogen to remove oxygen.

[0030] (4) Heat the reaction vessel to 115 °C, reflux and stir evenly. After 1 h of polymerization reaction, remove the water generated during the polymerization process under reduced pressure to increase the degree of polymerization, and continue the reaction for 2 h.

[0031] (5) Heat the reaction vessel to 160 °C to decompose the alkali gel, and the reaction time is 0.5 h. Then cool it down to room temperature.

[0032] (6) Dissolve 4.90 g of N-acetyl-L-cysteine ​​in 30 ml of anhydrous ethanol. After the reaction vessel is cooled to the target temperature, pour the solution into the reaction vessel, stir evenly, and purge with nitrogen gas. React for 2 h, then remove the organic solvent by vacuum distillation at 90 °C, cool to room temperature, and discharge the cysteine-modified aminopropyl silicone rubber, which is named O-NACSR.

[0033] (7) Weigh 10 g of the prepared O-NACSR and 6 g of vinyl MQ resin into a reaction vessel, add 20 ml of anhydrous ethanol as a solvent and adjust the viscosity of the system at the same time, add 0.16 g of photoinitiator 1173, stir evenly, remove bubbles and coat it on the PI film, place it in an 80 ℃ oven for 5 min to evaporate the solvent, then use a 365 nm ultraviolet light source to irradiate and perform click reaction curing for 2 min, and cure at room temperature for 24 h to obtain cysteine ​​modified organosilicon pressure-sensitive adhesive.

[0034] Example 3: This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive. The monomer components selected are as follows: 0.05 mol (10.32 g) of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, 0.09 mol (1.62 g) of deionized water, 0.1 mol (29.66 g) of octamethylcyclotetrasiloxane, 0.12 g of alkali adhesive, 0.04 mol (6.53 g) of N-acetyl-L-cysteine, 8 g of vinyl MQ resin, 0.18 g of photoinitiator, and 50 ml of anhydrous ethanol.

[0035] This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive, comprising the following steps: (1) Weigh 10.32 g of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane into a reaction vessel, add 1.62 g of deionized water and hydrolyze at room temperature for 0.5 h, while stirring evenly and purging with nitrogen.

[0036] (2) Heat the reaction vessel to 60 °C and distill under reduced pressure for 1 h while stirring evenly to remove excess water from the system.

[0037] (3) Weigh 29.66 g of octamethylcyclotetrasiloxane and 0.12 g of alkaline gel into a reaction vessel, stir evenly, and purge the system with nitrogen to remove oxygen.

[0038] (4) Heat the reaction vessel to 115 °C, reflux and stir evenly. After 1 h of polymerization reaction, remove the water generated during the polymerization process under reduced pressure to increase the degree of polymerization, and continue the reaction for 2 h.

[0039] (5) Heat the reaction vessel to 160 °C to decompose the alkali gel, and the reaction time is 0.5 h. Then cool it down to room temperature.

[0040] (6) Dissolve 6.53 g of N-acetyl-L-cysteine ​​in 30 ml of anhydrous ethanol. After the reaction vessel is cooled to the target temperature, pour the solution into the reaction vessel, stir evenly, and purge with nitrogen gas. React for 2 h, then remove the organic solvent by vacuum distillation at 90 °C, cool to room temperature, and discharge the cysteine-modified aminopropyl silicone rubber, which is named M-NACSR.

[0041] (7) Weigh 10 g of the prepared M-NACSR and 8 g of vinyl MQ resin into a reaction vessel, add 20 ml of anhydrous ethanol as a solvent and adjust the viscosity of the system at the same time, add 0.18 g of photoinitiator 1173, stir evenly, remove bubbles and coat it on the PI film, place it in an 80 ℃ oven for 5 min to evaporate the solvent, then use a 365 nm ultraviolet light source to irradiate and perform click reaction curing for 2 min, and cure at room temperature for 24 h to obtain cysteine ​​modified organosilicon pressure-sensitive adhesive.

[0042] Example 4: This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive. The monomer components selected are as follows: 0.05 mol (9.57 g) of γ-aminopropylmethyldiethoxysilane, 0.09 mol (1.62 g) of deionized water, 0.1 mol (29.66 g) of octamethylcyclotetrasiloxane, 0.12 g of alkali adhesive, 0.03 mol (4.90 g) of N-acetyl-L-cysteine, 6 g of vinyl MQ resin, 0.16 g of photoinitiator, and 50 ml of anhydrous ethanol.

[0043] This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive, comprising the following steps: (1) Weigh 9.57 g of γ-aminopropylmethyldiethoxysilane into a reaction vessel, add 1.62 g of deionized water and hydrolyze at room temperature for 0.5 h, while stirring evenly and purging with nitrogen.

[0044] (2) Heat the reaction vessel to 60 °C and distill under reduced pressure for 1 h while stirring evenly to remove excess water from the system.

[0045] (3) Weigh 29.66 g of octamethylcyclotetrasiloxane and 0.12 g of alkaline gel into a reaction vessel, stir evenly, and purge the system with nitrogen to remove oxygen.

[0046] (4) Heat the reaction vessel to 115 °C, reflux and stir evenly. After 1 h of polymerization reaction, remove the water generated during the polymerization process under reduced pressure to increase the degree of polymerization, and continue the reaction for 2 h.

[0047] (5) Heat the reaction vessel to 160 °C to decompose the alkali gel, and the reaction time is 0.5 h. Then cool it down to room temperature.

[0048] (6) Dissolve 4.90 g of N-acetyl-L-cysteine ​​in 30 ml of anhydrous ethanol. After the reaction vessel is cooled to the target temperature, pour the solution into the reaction vessel, stir evenly, and purge with nitrogen gas. React for 2 h, then remove the organic solvent by vacuum distillation at 90 °C, cool to room temperature, and discharge the cysteine-modified aminopropyl silicone rubber, which is named DE-NACSR.

[0049] (7) Weigh 10 g of the prepared DE-NACSR and 6 g of vinyl MQ resin into a reaction vessel, add 20 ml of anhydrous ethanol as a solvent and adjust the viscosity of the system at the same time, add 0.16 g of photoinitiator 1173, stir evenly, remove bubbles and coat it on the PI film, place it in an 80 ℃ oven for 5 min to evaporate the solvent, then use a 365 nm ultraviolet light source to irradiate and perform click reaction curing for 2 min, and age at room temperature for 24 h to obtain cysteine ​​modified organosilicon pressure-sensitive adhesive.

[0050] Example 5: This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive. The monomer components selected are as follows: N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane 0.05 mol (10.32 g), deionized water 0.09 mol (1.62 g), octamethylcyclotetrasiloxane 0.1 mol (29.66 g), alkali adhesive 0.12 g, L-cysteine ​​0.03 mol (3.63 g), vinyl MQ resin 6 g, photoinitiator 0.16 g, and anhydrous ethanol 50 ml.

[0051] This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive, comprising the following steps: (1) Weigh 10.32 g of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane into a reaction vessel, add 1.62 g of deionized water and hydrolyze at room temperature for 0.5 h, while stirring evenly and purging with nitrogen.

[0052] (2) Heat the reaction vessel to 60 °C and distill under reduced pressure for 1 h while stirring evenly to remove excess water from the system.

[0053] (3) Weigh 29.66 g of octamethylcyclotetrasiloxane and 0.12 g of alkaline gel into a reaction vessel, stir evenly, and purge the system with nitrogen to remove oxygen.

[0054] (4) Heat the reaction vessel to 115 °C, reflux and stir evenly. After 1 h of polymerization reaction, remove the water generated during the polymerization process under reduced pressure to increase the degree of polymerization, and continue the reaction for 2 h.

[0055] (5) Heat the reaction vessel to 160 °C to decompose the alkali gel, and the reaction time is 0.5 h. Then cool it down to room temperature.

[0056] (6) Dissolve 3.63 g of L-cysteine ​​in 30 ml of anhydrous ethanol. After the reaction vessel is cooled to the target temperature, pour the solution into the reaction vessel, stir evenly, and purge with nitrogen. React for 2 h, then remove the organic solvent by vacuum distillation at 90 °C, cool to room temperature, and discharge the cysteine-modified aminopropyl silicone rubber, which is named LCYSR.

[0057] (7) Weigh 10 g of the prepared LCYSR and 6 g of vinyl MQ resin into a reaction vessel, add 20 ml of anhydrous ethanol as a solvent and adjust the viscosity of the system at the same time, add 0.16 g of photoinitiator 1173, stir evenly, remove bubbles and coat on PI film, place in an 80 ℃ oven for 5 min to evaporate the solvent, then use a 365 nm ultraviolet light source to irradiate and perform click reaction curing for 2 min, and age at room temperature for 24 h to obtain cysteine ​​modified organosilicon pressure-sensitive adhesive.

[0058] Example 6: This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive. The monomer components selected are as follows: 0.05 mol (10.32 g) of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, 0.09 mol (1.62 g) of deionized water, 0.1 mol (29.66 g) of octamethylcyclotetrasiloxane, 0.12 g of alkali adhesive, 0.03 mol (4.92 g) of N-carbamoyl-L-cysteine, 6 g of vinyl MQ resin, 0.16 g of photoinitiator, and 50 ml of anhydrous ethanol.

[0059] This embodiment discloses a method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive, comprising the following steps: (1) Weigh 10.32 g of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane into a reaction vessel, add 1.62 g of deionized water and hydrolyze at room temperature for 0.5 h, while stirring evenly and purging with nitrogen.

[0060] (2) Heat the reaction vessel to 60 °C and distill under reduced pressure for 1 h while stirring evenly to remove excess water from the system.

[0061] (3) Weigh 29.66 g of octamethylcyclotetrasiloxane and 0.12 g of alkaline gel into a reaction vessel, stir evenly, and purge the system with nitrogen to remove oxygen.

[0062] (4) Heat the reaction vessel to 115 °C, reflux and stir evenly. After 1 h of polymerization reaction, remove the water generated during the polymerization process under reduced pressure to increase the degree of polymerization, and continue the reaction for 2 h.

[0063] (5) Heat the reaction vessel to 160 °C to decompose the alkali gel, and the reaction time is 0.5 h. Then cool it down to room temperature.

[0064] (6) Dissolve 4.92 g of N-acetyl-L-cysteine ​​in 30 ml of anhydrous ethanol. After the reaction vessel is cooled to the target temperature, pour the solution into the reaction vessel, stir evenly, and purge with nitrogen gas. React for 2 h, then remove the organic solvent by vacuum distillation at 90 °C, cool to room temperature, and discharge the cysteine-modified aminopropyl silicone rubber, which is named NFLSR.

[0065] (7) Weigh 10 g of the prepared NFLSR and 6 g of vinyl MQ resin into a reaction vessel, add 20 ml of anhydrous ethanol as a solvent and adjust the viscosity of the system at the same time, add 0.16 g of photoinitiator 1173, stir evenly, remove bubbles and coat it on the PI film, place it in an 80 ℃ oven for 5 min to evaporate the solvent, then use a 365 nm ultraviolet light source to irradiate and perform click reaction curing for 2 min, and cure at room temperature for 24 h to obtain cysteine ​​modified organosilicon pressure-sensitive adhesive.

[0066] To verify that cysteine-modified silicone rubber enables silicone pressure-sensitive adhesives to achieve high peel strength, the following control example was set up: Compare with Example 1: The composition of the monomers selected in this comparative example by weight is as follows: N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane 0.05 mol (10.32 g), deionized water 0.09 mol (1.62 g), octamethylcyclotetrasiloxane 0.1 mol (29.66 g), alkali gum 0.12 g, vinyl MQ resin 6 g, dibutyltin dilaurate 0.08 g, and anhydrous ethanol 50 ml.

[0067] The preparation method of this comparative example includes the following steps: (1) Weigh 10.32 g of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane into a reaction vessel, add 1.62 g of deionized water and hydrolyze at room temperature for 0.5 h, while stirring evenly and purging with nitrogen.

[0068] (2) Heat the reaction vessel to 60 °C and distill under reduced pressure for 1 h while stirring evenly to remove excess water from the system.

[0069] (3) Weigh 29.66 g of octamethylcyclotetrasiloxane and 0.12 g of alkaline gel into a reaction vessel, stir evenly, and purge the system with nitrogen to remove oxygen.

[0070] (4) Heat the reaction vessel to 115 °C, reflux and stir evenly. After 1 h of polymerization reaction, remove the water generated during the polymerization process under reduced pressure to increase the degree of polymerization, and continue the reaction for 2 h.

[0071] (5) Heat the reaction vessel to 160 °C to decompose the alkali gel, and the reaction time is 0.5 h. Then cool it down to room temperature and name it SR.

[0072] (6) Weigh 10 g of the prepared SR and 6 g of vinyl MQ resin into a reaction vessel, add 20 ml of anhydrous ethanol as a solvent and adjust the viscosity of the system at the same time, add 0.08 g of dibutyltin dilaurate, stir evenly, remove the bubbles and coat it on the PI film, place it in an 80 ℃ oven to cure for 10 min, and then mature at room temperature for 24 h to obtain unmodified organosilicon pressure-sensitive adhesive.

[0073] Examples 1 to 5 and Control Example 1 were subjected to 180° peel force test, 80°C high temperature holding test, thermogravimetric analysis test, and ring initial tack test. The test data are shown in the table below:

[0074] 1.180 ° Peeling force According to standard GB / T2792-2014, the samples were subjected to 180... ° Peel strength test. The coated samples were subjected to an electronic peel strength tester at 180°. ° Peel test. Cut the strip into 25 mm x 200 mm strips. Remove these strips from the release liner and apply them to a standard test plate. Roll them three times repeatedly with 2.5 kg rolls, then at a speed of 300 mm / min and a 180° speed. ° The speed was pulled out from the standard beta version.

[0075] 2. High-temperature tack The sample is coated between two substrates, cooled and cured, and then fixed in an oven "KJ-6012A Oven Type Tape Holding Force Tester" with a known weight of counterweight. After being suspended at a certain temperature for a period of time, the ability of the adhesive tape to resist pull-off is characterized by the displacement of the sample after adhesion or the time it takes for the sample to completely detach.

[0076] 3. Ring-shaped initial adhesion According to standard GB / T2792-2014, the test temperature is 23℃±2℃, and the humidity is 50%RH±5%RH. Test specimens should be placed for at least 4 hours before testing. Five specimens with a width of 25mm and a length of at least 175mm are used for testing. Before testing, remove the backing material of the adhesive tape, with the adhesive side facing outwards, and hold both ends of the tape to form a ring. Clamp the last 10mm of the ring into the upper clamp of the tension tester, with the ring hanging vertically downwards. Clamp the glass plate into the lower clamp, with its radial direction perpendicular to the radial direction of the adhesive tape. Bring the ring to contact the glass plate at a speed of 300mm / min. Immediately after contact, separate it in the opposite direction at a speed of 300mm / min. It is important to minimize the reverse separation lag time and record the maximum force value separating the ring and the glass plate.

[0077] The results in the table above show that the adhesion performance and high-temperature resistance of the prepared mussel-adhesive-enhanced silicone pressure-sensitive adhesive were effectively improved. Example 2 exhibited the best performance, with a 180° peel strength of 17.58 N / 25 mm, maintaining its adhesion at 80°C for 70 hours without detachment, achieving an initial ring tack of 12.51 N, and a 5% thermal weight loss temperature of 382.3°C, demonstrating superior adhesion and high-temperature resistance. This invention provides a novel modification process for silicone pressure-sensitive adhesives. The prepared cysteine-enhanced UV-cured high-peel-strength silicone pressure-sensitive adhesive meets the adhesion and high-temperature resistance requirements for bonding applications, exhibiting excellent performance.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A cysteine-reinforced UV-curable high-peel-strength silicone pressure-sensitive adhesive, characterized in that, The composition includes octamethylcyclotetrasiloxane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, deionized water, cysteine, initiator, synthesized cysteine-modified aminopropyl silicone rubber, vinyl MQ resin, and organic solvent. The octamethylcyclotetrasiloxane comprises 29.66 parts by mass, aminopropyl silane comprises 8.16–10.32 parts by mass, deionized water comprises 1.62 parts by mass, cysteine ​​comprises 3.26–6.53 parts by mass, alkali initiator comprises 0.12 parts by mass, cysteine-modified aminopropyl silicone rubber comprises 10 parts by mass, vinyl MQ resin comprises 4–8 parts by mass, photoinitiator comprises 0.14–0.18 parts by mass, and anhydrous ethanol comprises 50 parts by mass.

2. The cysteine-reinforced UV-curable high-peel-strength silicone pressure-sensitive adhesive according to claim 1, characterized in that, Aminopropylsilane is one or more of γ-aminopropylmethyldiethoxysilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, and 3-aminopropylmethyldimethoxysilane; Cysteine ​​is one or more of N-acetyl-L-cysteine, L-cysteine, and N-carbamoyl-L-cysteine.

3. The cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive according to claim 1, characterized in that, The photoinitiator used for the UV curing reaction of cysteine-modified aminopropyl silicone rubber and vinyl MQ resin is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

4. The cysteine-reinforced UV-curable high-peel-strength silicone pressure-sensitive adhesive according to claim 1, characterized in that, The organic solvent is anhydrous ethanol.

5. A method for preparing the organosilicon pressure-sensitive adhesive according to any one of claims 1 to 4, characterized in that, The specific steps include: Step 1: Weigh aminopropylsilane into a reaction vessel, add deionized water and hydrolyze at room temperature for 0.5 h, while stirring evenly and purging with nitrogen gas. Step 2: Heat the reaction vessel and perform vacuum distillation while stirring to remove excess water from the system. Step 3: Weigh octamethylcyclotetrasiloxane and alkaline gum into a reaction vessel, stir them evenly, and purge the system with nitrogen to remove oxygen. Step 4: Heat the reaction vessel, reflux it, and stir it evenly. After the polymerization reaction, remove the water generated during the polymerization process by reducing the pressure to increase the degree of polymerization. Continue the reaction for 2 hours. The molecular weight can be controlled by the polymerization time. Step 5: Heat the reaction vessel until the alkali gum is decomposed, and then cool it down to room temperature; Step 6: Dissolve cysteine ​​in anhydrous ethanol, add it to the reaction vessel after the reaction vessel has cooled to the target temperature, stir evenly, purge with nitrogen, react for 2 h, then remove the organic solvent by vacuum distillation, cool to room temperature, and discharge to obtain cysteine-modified aminopropyl silicone rubber. Step 7: Take the cysteine-modified aminopropyl silicone rubber and vinyl MQ resin prepared in Step 6 into a reaction vessel, add anhydrous ethanol as a solvent and adjust the viscosity of the system, and add 10 wt% photoinitiator 1173. Stir evenly, remove air bubbles, coat it on a PI film, place it in an oven for 5 min to evaporate the solvent, and then use a 365 nm ultraviolet light source to irradiate and perform a click reaction to cure, thus obtaining the cysteine-modified organosilicon pressure-sensitive adhesive.

6. The method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive according to claim 5, characterized in that, In step 2, the reaction vessel is heated to 60 °C and distilled under reduced pressure for 1 h.

7. The method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive according to claim 5, characterized in that, In step 4, the reaction vessel is heated to 115 °C, and after 1 hour of polymerization, the water generated during the polymerization process is removed by depressurization to increase the degree of polymerization.

8. The method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive according to claim 5, characterized in that, In step 5, the reaction vessel is heated to 160 °C to decompose the alkali gum, and the reaction time is 0.5 h.

9. The method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive according to claim 5, characterized in that, The decompression temperature in step 6 is 90 ℃.

10. The method for preparing a cysteine-enhanced UV-curable high-peel-strength silicone pressure-sensitive adhesive according to claim 5, characterized in that, In step 7, the temperature inside the drying oven is 80 ℃, and the click reaction curing time is 2 min.

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