A method for preparing UV-photoclick chemical debonding silicone pressure-sensitive tape

Abstract

This invention relates to the field of adhesive tape preparation technology, specifically to a method for preparing a UV photo-click chemical adhesive tape for debonding silicone pressure-sensitive adhesive. The method involves condensing and dehydrating vinyl MQ silicone resin and 107 silicone rubber under the action of Lewis acids or Lewis bases to obtain a grafted prepolymer. Thiol-based silicone oil, a photoinitiator, and an organotin or organotitanium catalyst are added to the grafted prepolymer solution. After coating and high-temperature drying, the residual silanol groups on the prepolymer undergo thermal condensation under the action of the catalyst, completing the first curing process and obtaining the silicone pressure-sensitive adhesive tape for bonding and fixing substrates. A second curing process is achieved through a thiol-olefin photoclick reaction, causing the silicone pressure-sensitive adhesive tape to lose its pressure-sensitive adhesiveness. This represents the tape debonding process at the end of the electronic component manufacturing process, allowing it to be easily peeled off from the surface of the substrate. This tape exhibits the high and low temperature resistance of conventional silicone pressure-sensitive adhesive tapes, maintaining adhesion from -50°C to 200°C, thus broadening the tape's operating temperature range.

Description

Technical Field

[0001] This invention relates to the field of debonding tape preparation technology, specifically to a method for preparing a UV-photoclick chemical debonding silicone pressure-sensitive tape. Background Technology

[0002] In the processing of precision components and the installation of PCBs, pressure-sensitive tapes are needed for temporary positioning of workpieces. These tapes have good adhesion at room temperature, but after the production process is completed, changes in light or heat cause the tape to lose its adhesiveness, allowing it to be easily peeled off the substrate. This facilitates automation and labor savings in the manufacturing process; in production, these products are commonly referred to as release tapes or anti-adhesion tapes.

[0003] Currently, the adhesive tapes on the market generally use two types of de-adhesion principles: thermal foaming de-adhesion and UV light de-adhesion.

[0004] Thermal foaming debonding occurs when the foaming powder in the adhesive layer expands upon heating, allowing the tape to easily separate from the substrate. This product utilizes the addition of a thermally foaming component to traditional pressure-sensitive adhesive formulations, such as adding thermally foaming materials to acrylic, polyurethane, or synthetic rubber-based pressure-sensitive adhesives. The prepared adhesive is coated, dried, rolled, and slit to obtain a tape product with initial tack. The drying temperature must not exceed the effective temperature of the foaming component. At room temperature, it forms a strong bond to the substrate. A secondary heating to the foaming powder's effective temperature significantly reduces the tape's peel strength, allowing it to be easily peeled off the bonded surface. For example, patent application CN108913051A involves adding thermally foaming particles to an acrylic pressure-sensitive adhesive formulation. The tape adheres pressure-sensitively at room temperature, but debonding occurs upon heating due to the expansion of the particles. The conductive pyrolytic adhesive tape disclosed in patent application CN109233676A is also produced by coating a conductive metal layer after film treatment with a heat-expanding foamable adhesive to form a pyrolytic adhesive layer. Some other tapes contain substances that produce gases such as CO2 or N2 when heated, causing them to expand and delaminate upon heating; this principle is similar to that of pyrolytic foamable adhesive tapes.

[0005] Existing UV-cured adhesive tapes are mostly made by blending acrylic acid or acrylic-modified polyurethane, polyurethane pressure-sensitive adhesive with UV monomers or oligomers, initiators, etc., to obtain the adhesive. Essentially, it's a two-in-one formulation of the original pressure-sensitive adhesive and UV monomers. The first step in production is coating and drying the adhesive, allowing the solvent to evaporate, followed by heat curing, and then winding and slitting to obtain a pressure-sensitive adhesive tape with initial tack. The subsequent stage involves UV irradiation, where the oligomers or unsaturated monomers undergo secondary curing under the action of a UV initiator. After curing, the adhesive surface hardens and shrinks in volume, thus significantly reducing the peel force and achieving the de-adhesion effect. Chinese invention patents CN114085621A, CN115322702A, CN115232578A, CN115181510A, and CN115305043A all employ similar process routes.

[0006] Both types of adhesive tapes mentioned above are based on carbon-based polymer resins or rubber, which are prone to losing adhesion under high and low temperature conditions. To improve adhesion performance, Henkel AG developed an optically transparent dual-curing adhesive using liquid polybutadiene as the pressure-sensitive polymer, blended with a UV initiator, a thermal initiator, and acrylic monomers to form the tape. This technology has been patented (application number 201110230724.1). The liquid polybutadiene itself possesses strong surface adhesion, allowing it to be coated to form the first step of the pressure-sensitive adhesive. The acrylic active monomers in the formulation undergo a second curing process under UV light, achieving higher adhesion rather than simply increasing crosslinking density for easier debonding.

[0007] Other dual-curing technologies include patents from Henckel Corporation (USA) on a rapid moisture-curing and UV-moisture dual-curing composition (CN 1705684 B) and patents from Beijing University of Chemical Technology on a dual-curable polysiloxane acrylate resin and its preparation method (CN 102408569 B). Both technologies first use ultraviolet light to initiate methacryloyloxy radical polymerization. Since photopolymerization activity is low, a large irradiation dose is required for curing. Then, Si-OR hydrolysis-condensation curing is completed by slowly absorbing moisture from the air. This secondary curing reaction is slow and simultaneously interacts with the hydroxyl groups on the adherend to form covalent bonds. This further improves adhesion rather than reducing the force between the adherend and the bond.

[0008] Chinese patent application number 201410146939.9 discloses a UV / moisture dual-curing silicone resin composition. It uses vinyl alkoxy-terminated silicone oil and mercapto silicone oil as the main polymers. The vinyl and mercapto groups form initial curing after UV irradiation, while the residual alkoxy groups undergo slow hydrolysis upon subsequent contact with moisture to complete secondary curing. Secondary curing relies on the slow penetration of moisture to occur, and the reaction time is relatively long, typically over 168 hours. Similar to CN 1705684 B and CN102408569 B, while the number of crosslinking points increases during secondary curing, the adhesion is also enhanced due to the interaction between Si-OR and the OH groups on the adherend, resulting in a semi-permanent bond. The secondary curing reaction is intended to strengthen the bond, not to facilitate debonding.

[0009] In summary, silicone-based UV + moisture-cured adhesives cannot be debonded. Carbon-based polymer pressure-sensitive tapes have poor high and low temperature resistance. Especially under high-temperature conditions, such as 250℃ wave soldering, the adhesive surface tack will decrease sharply or even disappear. Furthermore, the accompanying thermal decomposition and chain scission reaction reduces the material's cohesion, making it easy for adhesive residue to remain on the adhered surface during tape debonding, leading to an increased product defect rate. Summary of the Invention

[0010] In order to overcome the above-mentioned technical problems, the present invention provides a method for preparing UV-photoclick chemical debonding silicone pressure-sensitive tape, which can completely solve the above-mentioned technical problems.

[0011] The technical solutions to the above technical problems are as follows:

[0012] The preparation method of this UV-photoclick chemical debonding silicone pressure-sensitive tape includes the following steps:

[0013] Step 1): Chain extension prepolymerization. This synthesis step aims to increase the polymer molecular weight and enhance the cohesive force of the material, thereby preventing residue from appearing when the tape is peeled off from the substrate. Vinyl MQ silicone resin and 107 silicone rubber are subjected to a condensation dehydration reaction in the presence of Lewis acids or Lewis bases, using toluene, xylene, methylcyclohexane, or ethylcyclohexane as solvents, at a mass ratio of 10:7–8. The reaction is carried out at a temperature of 100–110°C and stirred for 2–3 hours. The reaction is terminated by neutralization of the catalyst, followed by vacuum distillation to obtain a grafted prepolymer solution with a solid content of 60 ± 10% as shown in Formula I.

[0014] The condensation reaction catalyst is a Lewis acid or base. After the reaction, the catalyst needs to be neutralized to avoid acid or base residue in the formulation. Because acids and bases can catalyze the elimination reaction of mercapto silicone oil, the UV curing and debonding process of the addition reaction in step 3) cannot proceed.

[0015] The reaction equation is as follows:

[0016]

[0017] Among them, the vinyl MQ silicone resin is a vinyl MQ silicone resin with M / Q = 0.6 to 1.0, vinyl content % (wt) 0.1 to 2.0%, and OH content % (wt) 0.5 to 2.5%;

[0018] The molecular weight M of 107 silicone rubber W The figure is between 650,000 and 900,000.

[0019] Step 2): One-time curing

[0020] A photoinitiator and mercaptosilicone oil with a SH content of 1-5% by mass, preferably mercaptosilicone oil with a SH content of 1-2% by mass, are added to the grafted prepolymer solution shown in Formula I. The amount of mercaptosilicone oil added is such that the mass ratio of vinyl MQ silicone resin to mercaptosilicone oil in step 1) is 10:3-4. The mixture is stirred evenly to obtain a glue, and then an organotin or organotitanium catalyst is added to the glue. The amount of organotin or organotitanium catalyst added is 0.05-2% by mass of the glue, and the mixture is stirred evenly. The mixture is coated on the surface of the substrate to form a dry film of 20-40 μm, and then dried in an oven at 120-165°C for 2 minutes to complete the first curing. At the end of the coating production line, a fluorine release film is covered on the pressure-sensitive adhesive side, and a self-adhesive light-shielding aluminum foil is attached to the backing side. The film is then wound up and slit to obtain an organosilicon pressure-sensitive tape. The substrate includes, but is not limited to, polyethylene terephthalate (PET), propylene oxide (PO), thermoplastic polyurethane elastomer rubber (TPU), and polyimide (PI).

[0021] In this step, organotin or organotitanium catalysts can catalyze the thermal condensation of residual silanol groups on the prepolymer, curing them to form a viscoelastic adhesive layer, resulting in a tape with pressure-sensitive adhesive properties on the surface.

[0022] The pressure-sensitive adhesive side is covered with a fluoropolymer release film, which should be peeled off before application. A self-adhesive light-shielding aluminum foil is applied to the adhesive side to prevent the pressure-sensitive tape from deteriorating and losing its adhesiveness due to trace amounts of ultraviolet radiation from natural light during packaging and storage. The light-shielding aluminum foil can be removed before application or from the film before UV debonding.

[0023] Step 3): Secondary curing, i.e., mercapto-olefin photoclick reaction.

[0024] The secondary curing is an addition reaction between the C=C double bond on the grafted prepolymer shown in Formula I in step 2) and the SH of the mercapto silicone oil under the action of photoinitiator and UV, which causes the organosilicon pressure-sensitive tape in step 2) to lose its viscoelasticity and achieve de-adhesion;

[0025] The reaction equation is as follows:

[0026]

[0027] UV click chemistry refers to the addition reaction of photocurable groups in the adhesive layer under the action of photoinitiator and UV light. The photoinitiator includes any one or a combination of several of the following: ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, 2-isopropylthioxanthone, benzophenone, and 2,2-diethoxy-1-phenylhexanone. The amount of initiator added is 5-10% by mass of the vinyl MQ silicone resin described in step 1).

[0028] The first thermal curing step (i.e., primary curing) after adhesive coating cannot utilize the more common Pt-catalyzed addition curing and peroxide hydrogen abstraction crosslinking methods found in silicone pressure-sensitive adhesives. This is because mercaptosilicone oils, being organosulfur compounds, will poison the Pt catalyst, preventing addition curing. Furthermore, peroxide hydrogen abstraction crosslinking initiators, such as BPO and DCBP, are strong oxidizing agents that will oxidize SH to form sulfur oxides, thus losing their UV click reactivity. Therefore, organotin or organotitanium catalysts are chosen as the catalysts for the first thermal curing step.

[0029] To increase the crosslinking density during subsequent UV curing, 107 silicone rubber can also be replaced with 107 silicone rubber with hydroxyl-terminated vinyl groups on the side chains, as shown in the following structural formula:

[0030]

[0031] The reaction equation is as follows:

[0032]

[0033] Correspondingly, step 3) is the addition reaction between the grafted prepolymer solution shown in Formula IV and the mercapto silicone oil under the action of a photoinitiator and UV to achieve debinding, and the reaction mechanism is the same as described above.

[0034] The reaction between the grafted prepolymer solution shown in Formula IV and mercapto silicone oil is also an addition reaction. Both types of Si-CH=CH2 on the grafted prepolymer shown in Formula IV will undergo addition reactions with SH.

[0035] Alternatively, vinyl MQ silicone resin can be replaced with methyl MQ silicone resin;

[0036] It is worth noting that when the vinyl MQ silicone resin in step 1) is replaced with methyl MQ silicone resin, the 107 silicone rubber in the original formulation needs to be replaced with 107 silicone rubber with vinyl-terminated hydroxyl groups on the side chains of the molecular chain. This is to ensure that the obtained grafted prepolymer has Si-CH=CH2, so as to guarantee that it can undergo an addition reaction with SH in the subsequent process.

[0037] The methyl MQ silicone resin is a methyl MQ silicone resin with an M / Q ratio of 0.6 to 1.0 and an OH content of 0.5 to 2.5% (wt).

[0038] The molecular weight M of silicone rubber with vinyl-terminated hydroxyl groups on the side chain is 107. W The content is 650,000 to 900,000; the vinyl content (wt%) is 0.1% to 1.0%.

[0039] The reaction equation is as follows:

[0040]

[0041] Correspondingly, step 3) is the addition reaction between the grafted prepolymer solution shown in Formula III and mercaptosilicone oil under the action of photoinitiator and UV to achieve debinding, and the reaction mechanism is the same as described above.

[0042] Organotin or organotitanium acts as a catalyst to catalyze the thermal condensation and curing of Si-OH, forming a cross-linked network. This cross-linked network consists of soft-hard blocks, exhibiting good cohesion and pressure sensitivity.

[0043] The reaction is shown below:

[0044]

[0045] For ease of understanding, the pressure-sensitive cross-linked network grafted prepolymers shown in Formulas II, III, and IV are all represented by the following structural formulas:

[0046]

[0047] The pressure-sensitive crosslinking network with vinyl C=C undergoes an addition reaction with mercapto silicone oil, namely a mercapto-olefin photoclick reaction, and a secondary curing reaction of Si-CH=CH2 and SH under UV irradiation. The reaction equations are shown below:

[0048]

[0049] The beneficial effects of this invention are:

[0050] This invention provides a wider operating temperature range for downstream production, offering a wider selection of UV-sensitive adhesive tapes. Common pressure-sensitive adhesives such as acrylic resins, polyurethane resins, and synthetic rubbers, due to their high Tg and poor ultimate heat resistance, are typically only usable within a temperature range of room temperature to 120°C. Organosilicon molecules, with their high Si-O-Si bond energy and low-temperature flexibility, allow for tapes that can be used at temperatures up to 200°C, and maintain stable performance even at short-term temperatures of 260°C.

[0051] This invention uses silicone resin and silicone rubber as the main polymers, which are first thermally condensed and cured in one step to form a silicone pressure-sensitive adhesive layer. At the end of the process, a mercapto-olefin photo-click reaction is performed, followed by a second UV curing process that eliminates the adhesiveness, allowing for easy unbinding. The tape possesses the high and low temperature resistance of conventional silicone pressure-sensitive tapes, maintaining adhesion from -50 to 200°C, thus widening the tape's operating temperature range. The silicone pressure-sensitive adhesive also loses its viscoelasticity at low temperatures under UV irradiation, making it easy to peel off completely.

[0052] The first step involves using vinyl MQ silicone resin and α,ω-dihydroxy polydimethylsiloxane (107 silicone rubber) or methyl MQ silicone resin and α,ω-dihydroxy polymethylvinylsiloxane (107 silicone rubber with vinyl-terminated hydroxyl groups on the side chain) under the action of Lewis acid or Lewis base to catalyze the condensation reaction between the Si-OH groups on the MQ silicone resin and the Si-OH groups on the end groups of the silicone rubber, thus obtaining a grafted prepolymer. The prepolymer is first neutralized by the catalyst, then mercapto silicone oil, a photoinitiator, and another catalyst are added. After thorough mixing, the mixture is coated, dried, wound, and slit to obtain a pressure-sensitive adhesive tape containing C=C and SH.

[0053] The second step is the debonding stage. The pressure-sensitive adhesive layer with C=C and SH obtained in the first step, along with the photoinitiator, forms a curing system that is further cured by UV light irradiation. UV secondary curing is achieved through a mercapto-olefin photoclick reaction. This reaction is fast, not easily affected by oxygen inhibition, easily releases shrinkage stress, and does not cause product deformation. The silicone pressure-sensitive adhesive loses its viscoelasticity at low temperatures, making it easy to peel off completely. It is very suitable for temporary positioning of workpieces in the production of optical devices and electronic materials.

[0054] The present invention will now be described in further detail with reference to specific embodiments. Detailed Implementation

[0055] Example 1:

[0056] ① Rubber compound preparation: In a 1000ml brown glass flask, add 100 parts toluene, 100 parts vinyl MQ silicone resin (M / Q = 0.6, vinyl content % (wt) 0.1%, OH content % (wt) 0.5%), 80 parts 107 silicone rubber (Mw = 800,000), and 0.1 parts ethylenediamine. Heat to reflux at 110℃, fractionate off the water produced by condensation, and stir for 2 hours. Cool with cooling water to below 40℃, and add an appropriate amount of acetic acid to neutralize to pH = 7. Add 30 parts mercaptosilicone oil (SH content 2%) and 8 parts TPO-L photoinitiator, and stir for 1 hour. Filter and seal to obtain a rubber compound with a solid content of 50%.

[0057] ② Coating:

[0058] Before coating, 0.1 parts of dibutyltin dilaurate were added to 100 parts of the adhesive. A 25-micron dry film was coated onto a 100μm PET film and dried in a 120℃ oven for 2 minutes to remove the solvent. At the end of the coating line, a fluorine release film was applied to the pressure-sensitive adhesive side, and a self-adhesive light-shielding aluminum foil was attached to the adhesive backing side, completing the winding process. After winding, the tape was slit to obtain 25mm wide release tape. The resulting tape initially adhered to a 22# steel ball, with a 180° peel strength of 5.5N / 25mm. After the bonding process, the tape was exposed to an LED light source at a wavelength of 365nm for 3 seconds, achieving a strength of 3000mJ / cm². 2 After energy irradiation, the interfacial peel strength decreased to 0.13 N / 25 mm. Residue-free peeling can be easily achieved.

[0059] Example 2:

[0060] ① Rubber compound preparation: In a 1000ml brown glass flask, add 220 parts of methylcyclohexane, 100 parts of vinyl MQ silicone resin with M / Q = 1.0, vinyl content % (wt) 1.0%, and OH content % (wt) 1.5%, 70 parts of 107 silicone rubber with Mw = 650,000, and 0.1 parts of triethylamine. Heat to reflux at 100℃, fractionate off water, and stir for 2 hours. Cool with cooling water to below 40℃, and add an appropriate amount of acetic acid to neutralize to pH = 7. Add 40 parts of mercapto silicone oil with SH content of 2.6%, 5 parts each of DEAP and 184 photoinitiator, and stir for 1 hour. Filter and seal to obtain a rubber compound with a solid content of 60%.

[0061] ② Coating:

[0062] Before coating, 1 part tetraisopropyl titanate was added to 100 parts of the adhesive. A 25-micron dry film was coated on a 100μm PI film and dried in a 140℃ oven for 2 minutes to remove the solvent. At the end of the coating line, a fluorine release film was applied to the pressure-sensitive adhesive side, and a self-adhesive light-shielding aluminum foil was attached to the adhesive backing side, completing the winding process. After winding, the tape was slit to obtain 25mm wide release tape. The resulting tape initially adhered to a 21# steel ball, with a 180° peel strength of 6.3N / 25mm. After the fixing and bonding process, the tape was exposed to an LED light source at a wavelength of 365nm for 4 seconds, achieving a strength of 4000mJ / cm. 2 After energy irradiation, the interfacial peel strength decreased to 0.1 N / 25 mm. Residue-free peeling can be easily achieved.

[0063] Example 3:

[0064] ① Rubber compound preparation: In a 1000ml brown glass flask, add 300 parts xylene, 100 parts vinyl MQ silicone resin (M / Q = 0.8, vinyl content % (wt) 2.0%, OH content % (wt) 2.5%), 80 parts 107 silicone rubber (Mw = 900,000), and 0.4 parts acetic acid. Heat to reflux at 110℃, fractionate off water, and stir for 2 hours. Cool with cooling water to below 40℃. Neutralize to pH = 7 with an appropriate amount of ethylenediamine. Add 30 parts mercapto silicone oil (SH content 1.3%), 3 parts each of 1173 photoinitiator and ITX photoinitiator, and stir for 1 hour. Filter and seal to obtain a rubber compound with a solid content of 55%.

[0065] ② Coating:

[0066] Before coating, 0.1 parts of dibutyltin diacetate were added to 100 parts of the adhesive. A 25-micron dry film was coated onto a 100μm TPU film and dried in a 165℃ oven for 2 minutes to remove the solvent. At the end of the coating line, a fluorine release film was applied to the pressure-sensitive adhesive side, and a self-adhesive light-shielding aluminum foil was attached to the adhesive backing side, completing the winding process. After winding, the tape was slit to obtain 25mm wide release tape. The resulting tape initially adhered to a 22# steel ball, with a 180° peel strength of 5.8N / 25mm. After the bonding process, the tape was exposed to an LED light source at a wavelength of 365nm for 3 seconds, achieving a strength of 3000mJ / cm². 2 After energy irradiation, the interfacial peel strength decreased to 0.12 N / 25 mm. Residue-free peeling can be easily achieved.

[0067] Example 4:

[0068] ① Rubber compound preparation: In a 1000ml brown glass flask, add 400 parts of ethylcyclohexane, 100 parts of methyl MQ silicone resin with M / Q = 1.0 and OH content % (wt) 1.5%, 70 parts of 107 silicone rubber with vinyl-terminated hydroxyl groups on the side chain and Mw = 650,000, and 0.5 parts of triethylamine. Heat to reflux at 110℃, fractionate off water, and stir for 2 hours. Cool with cooling water to below 40℃, and neutralize to pH = 7 with formic acid. Add 40 parts of mercapto silicone oil with SH content 4.5% and 9 parts of 1173 photoinitiator, and stir for 1 hour. Filter and seal to obtain a rubber compound with a solid content of 70%.

[0069] ② Coating:

[0070] Before coating, 1 part tetrabutyl titanate was added to 100 parts of the adhesive. A 25-micron dry film was coated on a 100μm PO film and dried in a 135℃ oven for 2 minutes to remove the solvent. At the end of the coating line, a fluorine release film was applied to the pressure-sensitive adhesive side, and a self-adhesive light-shielding aluminum foil was attached to the adhesive backing side, completing the winding process. After winding, the tape was slit to obtain 25mm wide release tape. The resulting tape initially adhered to a 23# steel ball, with a 180° peel strength of 6.8N / 25mm. After the fixing and bonding process, the tape was exposed to an LED light source at a wavelength of 365nm for 4 seconds, achieving a strength of 4000mJ / cm². 2 After energy irradiation, the interfacial peel strength decreased to 0.15 N / 25 mm. Residue-free peeling can be easily achieved.

[0071] Example 5:

[0072] ① Rubber compound preparation: In a 1000ml brown glass flask, add 150 parts of methylcyclohexane, 100 parts of methylMQ silicone resin with M / Q = 0.75 and OH content % (wt) 2.5%, 70 parts of 107 silicone rubber with vinyl-terminated hydroxyl groups on the side chain and Mw = 650,000, and 0.25 parts of ethylenediamine. Heat to reflux at 100℃, fractionate off the water produced by condensation, and stir for 2 hours. Cool with cooling water to below 40℃, and add an appropriate amount of propionic acid to neutralize to pH = 7. Add 40 parts of mercaptosilicone oil with SH content 3.6%, 5 parts each of DEAP and 184 photoinitiator, and stir for 1 hour. Filter and seal to obtain a rubber compound with a solid content of 60%.

[0073] ② Coating:

[0074] Before coating, 0.2 parts of dibutyltin dilaurate were added to 100 parts of the adhesive. A 25-micron dry film was coated onto a 100μm PET film and dried in a 120℃ oven for 2 minutes to remove the solvent. At the end of the coating line, a fluorine release film was applied to the pressure-sensitive adhesive side, and a self-adhesive light-shielding aluminum foil was attached to the adhesive backing side, completing the winding process. After winding, the tape was slit to obtain 25mm wide release tape. The resulting tape initially adhered to a 20# steel ball, with a 180° peel strength of 5.5N / 25mm. After the bonding process, the tape was exposed to an LED light source at a wavelength of 365nm for 3 seconds, achieving a strength of 3000mJ / cm². 2 After energy irradiation, the interfacial peel strength decreased to 0.13 N / 25 mm. Residue-free peeling can be easily achieved.

[0075] Example 6:

[0076] ① Rubber compound preparation: In a 1000ml brown glass flask, add 280 parts toluene, 100 parts methyl MQ silicone resin (M / Q = 1.0, OH content % (wt) 0.5%), 70 parts 107 silicone rubber with vinyl-terminated hydroxyl groups on the side chain (VW = 650,000) and vinyl content % (wt), and 0.3 parts propylenediamine. Heat to reflux at 110℃, fractionate off the water produced by condensation, and stir for 2 hours. Cool with cooling water to below 40℃, and neutralize to pH = 7 with acetic acid. Add 40 parts mercapto silicone oil (SH content 1.8%) and 5 parts DEAP photoinitiator, and stir for 1 hour. Filter and seal to obtain a rubber compound with a solid content of 65%.

[0077] ② Coating:

[0078] Before coating, 1.2 parts of ethyl acetoacetate titanium composite were added to 100 parts of the adhesive. A 25-micron dry film was coated on a 100μm PI film and dried in a 140℃ oven for 2 minutes to remove the solvent. At the end of the coating line, a fluorine release film was applied to the pressure-sensitive adhesive side, and a self-adhesive light-shielding aluminum foil was attached to the adhesive backing side, completing the winding process. After winding, the tape was slit to obtain 25mm wide release tape. The resulting tape initially adhered to a 19# steel ball, with a 180° peel strength of 6.3N / 25mm. After the fixing and bonding process, the tape was exposed to an LED light source at a wavelength of 365nm for 3 seconds, achieving a peel strength of 3000mJ / cm. 2 After energy irradiation, the interfacial peel strength decreased to 0.1 N / 25 mm. Residue-free peeling can be easily achieved.

[0079] Example 7:

[0080] ① Rubber compound preparation: In a 1000ml brown glass flask, add 250 parts xylene, 100 parts vinyl MQ silicone resin (M / Q = 0.6, vinyl content % (wt) 1.0%, OH content % (wt) 1.5%), and 70 parts 107 silicone rubber with vinyl-terminated hydroxyl groups on the side chains (vinyl content % (wt) 0.75%, Mw = 750,000). Add 0.4 parts propionic acid, heat to reflux at 110℃, fractionate off the water produced by condensation, and stir for 2 hours. Cool with cooling water to below 40℃, and add an appropriate amount of propylenediamine to neutralize to pH = 7. Add 40 parts mercaptosilicone oil (SH content 2.0%) and 7 parts 184 photoinitiator, and stir for 1 hour. Filter and seal to obtain a rubber compound with a solid content of 50%.

[0081] ② Coating:

[0082] Before coating, 1 part tetratert-butyl titanate was added to 100 parts of the adhesive. A 25-micron dry film was coated on a 100μm TPU film and dried in a 130℃ oven for 2 minutes to remove the solvent. At the end of the coating line, a fluorine release film was applied to the pressure-sensitive adhesive side, and a self-adhesive light-shielding aluminum foil was attached to the adhesive backing side, completing the winding process. After winding, the tape was slit to obtain 25mm wide release tape. The resulting tape initially bonded to a 22# steel ball, with a 180° peel strength of 5.8N / 25mm. After the fixing and bonding process, the tape was exposed to an LED light source at a wavelength of 385nm for 3 seconds, achieving a peel strength of 3000mJ / cm. 2 After energy irradiation, the interfacial peel strength decreased to 0.12 N / 25 mm. Residue-free peeling can be easily achieved.

[0083] Comparative Example 1:

[0084] Referring to the formulation of Example 1 of the UV / moisture dual-curing silicone resin composition disclosed in the background art (application number 201410146939.9), an alkoxy silicone oil with vinyl side chains at both ends is combined with a mercapto silicone oil. A photoinitiator and a moisture curing catalyst are simultaneously added to the formulation, and the prepared silicone resin composition is used as a coating adhesive for curing tests.

[0085] First, the silicone resin composition is irradiated with UV light at an energy of 1000 mJ / cm². 2 The colloidal curing hardness (Shore 00) is 44. After slow moisture absorption and curing for 7 days, the hardness can increase to 65. The silane groups in the secondary curing reaction are located on the side chains of the silicone oil molecule, exhibiting greater steric hindrance and lower moisture reactivity compared to the end groups. Therefore, a 7-day curing period is required before testing. Similar to the mechanism of action of silane coupling agents, the hydrolysis reaction of silane groups strengthens the cross-linking network and also enhances adhesion to the substrate, preventing debonding.

[0086] Comparative Example 2:

[0087] Referring to the formulation of Example 1 in the Chinese patent application (application number 201911397730.9), which discloses a photocurable silicone liquid coating material, its preparation method, and its application, sulfhydryl silane is used to graft fumed silica onto the surface, effectively obtaining a fumed silica powder encapsulated in sulfhydryl silane as a crosslinking agent. Then, in combination with vinyl silicone oil, under the action of a photoinitiator, the vinyl and sulfhydryl groups react at low temperature to form crosslinks. This yields a low-energy, low-VOC fiber sleeving adhesive. It can replace traditional Pt thermocatalytic reactions and silicone rubber products cured by the addition of vinyl and hydrogen silane. The technical route involves one-time curing to form a coating bond on the fiber sleeving surface, without secondary curing, debonding, or peeling.

[0088] The performance test data of the tapes in Examples 1-7 and Comparative Examples 1-2 are shown in Table 1 below:

[0089] Table 1

[0090]

[0091] As shown in Table 1 above, the tape obtained by this invention can rapidly undergo secondary curing and debonding after UV light irradiation. After debonding, it is easy to peel off completely, leaving no adhesive residue on the substrate. This invention achieves pressure-sensitive adhesion and UV secondary curing and debonding through a mercapto-olefin photoclick reaction. The tape possesses the high and low temperature resistance characteristics of conventional silicone pressure-sensitive tapes, maintaining adhesion from -50 to 200°C, thus widening the tape's operating temperature range. At low temperatures, the silicone pressure-sensitive adhesive loses its viscoelasticity upon UV irradiation, making it easy to peel off completely.

[0092] Therefore, based on the above data characterization, the unadhesive tape provided by the present invention is suitable for the following scenarios:

[0093] 1. Used for cutting and positioning of multilayer ceramic chip capacitors (MLCC) and multilayer ceramic chip inductors (MLCI);

[0094] 2. Used for positioning and machining small, precision, surface-mount electronic components;

[0095] 3. Used for temporary positioning in the machining of precision components;

[0096] 4. Circuit board mounting component positioning;

[0097] 5. Positioning printing of electronic components such as ring-shaped varistors;

[0098] 6. Can replace blue film processing and positioning;

[0099] 7. For SAWING processing, etc.

[0100] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a UV-photoclick chemical debonding silicone pressure-sensitive adhesive tape, characterized in that, Includes the following steps: Step 1): Chain extension prepolymerization Vinyl MQ silicone resin and 107 silicone rubber were subjected to a condensation and dehydration reaction in a solvent at a mass ratio of 10:7-8 under the action of Lewis acid or Lewis base, followed by neutralization of the catalyst, to obtain the grafted prepolymer solution shown in Formula I. The reaction equation is as follows: ； The vinyl MQ silicone resin has an M / Q ratio of 0.6 to 1.0 and a vinyl content of w. t % 0.1~2.0%, OH content w t 0.5%–2.5% vinyl MQ silicone resin; The molecular weight M of the 107 silicone rubber W The figure is between 650,000 and 900,000. Step 2): One-time curing Thiol-based silicone oil and photoinitiator are added to the grafted prepolymer solution shown in Formula I and stirred evenly to obtain a colloid. Then, organotin or organotitanium catalyst is added to the colloid, mixed evenly, and coated onto the surface of the substrate to form a 20-40 μm dry film. After drying in a 120-165℃ oven for 2 minutes, a first curing is completed. After being wound, slit, and packaged, an organosilicon pressure-sensitive tape is obtained. The adhesive side of the organosilicon pressure-sensitive tape is covered with a fluorine release film, and the backing side is covered with self-adhesive light-shielding aluminum foil. The mercaptosilicone oil is a mercaptosilicone oil with an SH content of 1-5% by mass; the amount of mercaptosilicone oil added is such that the mass ratio of the vinyl MQ silicone resin in step 1) to the mercaptosilicone oil in step 2) is 10:3-4. Step 3): Secondary curing The secondary curing is an addition reaction between the C=C double bond on the grafted prepolymer shown in Formula I in step 2) and the SH of the mercapto silicone oil under the action of a photoinitiator and UV, which causes the silicone pressure-sensitive tape in step 2) to lose its viscoelasticity and achieve de-adhesion. The reaction equation is as follows: 。 2. The method for preparing UV-photoclick chemical debonding silicone pressure-sensitive tape according to claim 1, characterized in that, The heating temperature of the condensation dehydration reaction described in step 1) is 100-110℃; the stirring time is 2-3h; and the prepolymer solution with a solid content of 60±10% is obtained by vacuum distillation dehydration; the solvents used include toluene, xylene, methylcyclohexane or ethylcyclohexane.

3. The method for preparing UV-photoclick chemical debonding silicone pressure-sensitive tape according to claim 1, characterized in that, The mercaptosilicone oil mentioned is a mercaptosilicone oil with an SH content of 1-2% by mass.

4. The method for preparing UV-photoclick chemical debonding silicone pressure-sensitive tape according to claim 1, characterized in that, In step 2), the amount of organotin or organotitanium catalyst added is 0.05 to 2% of the mass of the rubber compound; the substrate includes polyethylene terephthalate, thermoplastic polyurethane elastomer rubber, and polyimide.

5. The method for preparing UV-photoclick chemical debonding silicone pressure-sensitive tape according to claim 1, characterized in that, The photoinitiator mentioned in steps 2) and 3) includes any one or a combination of several of the following: ethyl 2,4,6-trimethylbenzoylphenylphosphonate, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, 2-isopropylthioxanthone, benzophenone, and 2,2-diethoxy-1-phenylhexanone. The amount of photoinitiator added is 5 to 10% by mass of the vinyl MQ silicone resin mentioned in step 1).

6. The method for preparing UV photoclick chemical debonding silicone pressure-sensitive tape according to any one of claims 1-5, characterized in that, In step 1), the vinyl MQ silicone resin is replaced with methyl MQ silicone resin. When methyl MQ silicone resin is used, the 107 silicone rubber is replaced with 107 silicone rubber with vinyl-terminated hydroxyl groups on the side chains. The 107 silicone rubber with vinyl-terminated hydroxyl groups on the side chains has the following structure: ； The methyl MQ silicone resin has an M / Q ratio of 0.6 to 1.0 and an OH content of w t 0.5%–2.5% methyl MQ silicone resin; The molecular weight M of the silicone rubber with vinyl-terminated hydroxyl groups on its side chains is [missing information]. W The content is 650,000 to 900,000; the vinyl content is w t % 0.1~1.0%; The reaction equation is as follows: 。

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