Chemically bonded ionic liquid electro-debondable silicone pressure sensitive adhesive and method of making

Abstract

This invention relates to an electro-detachable silicone pressure-sensitive adhesive with chemically bonded ionic liquids and its preparation method. The invention addresses the problem that existing electro-detachable technologies significantly compromise the transparency and initial peel strength of pressure-sensitive adhesives, and also lead to a severe degradation of electro-responsive detachable performance over time. This invention utilizes a platinum-catalyzed hydrosilylation reaction between an ionic liquid containing reactive double bonds, vinyl silicone raw material, and a hydrogen-containing polysiloxane. The cationic or anionic framework of the ionic liquid is permanently covalently bonded to the three-dimensional silicone network as side groups or crosslinking points. When a DC voltage is applied, the free counterions rapidly migrate and accumulate at the interface under the drive of the electric field, forming a strong double-layer polarization effect. This instantly disrupts the van der Waals forces and hydrogen bonds at the interface, resulting in a sharp decrease in peel strength, thus achieving both high initial tack and excellent electro-detachable responsiveness. This invention belongs to the field of pressure-sensitive adhesive preparation technology.

Description

Technical Field

[0001] This invention relates to an electro-debonding silicone pressure-sensitive adhesive and its preparation method, belonging to the field of pressure-sensitive adhesive preparation technology. Background Technology

[0002] Silicone pressure-sensitive adhesives (SPSAs) hold a crucial position in high-value-added fields such as flexible electronics assembly and semiconductor packaging due to their excellent resistance to high and low temperatures, weather resistance, and adhesion to low surface energy substrates. However, as electronic products evolve towards shorter cycle times, easier recycling, and the return of high-value components, the "easy to stick but difficult to peel" characteristic of traditional SPSAs makes them highly susceptible to damage to fragile flexible screens or ultra-thin chips during disassembly. To address this issue, electro-induced debonding technology has emerged. Existing technologies often involve physically blending conventional ionic liquids as conductive media into the silicone system. However, there is a significant thermodynamic incompatibility between highly polar ionic liquids and non-polar polysiloxanes. Physical blending leads to severe agglomeration and phase separation of the ionic liquid in the matrix, resulting in an "oil seepage" phenomenon on the adhesive surface. This not only significantly degrades the transparency and initial peel strength of the SPSA but also causes a severe decline in its electro-responsive debonding performance over time. Summary of the Invention

[0003] To address the problem that existing electro-induced debonding technologies significantly damage the transparency and initial peel strength of pressure-sensitive adhesives, and also cause a severe decline in electro-responsive debonding performance over time, this invention proposes a chemically bonded ionic liquid-based electro-induced debonding silicone pressure-sensitive adhesive and its preparation method.

[0004] The technical solution adopted by the present invention to solve the above problems is as follows: The electro-debonding organosilicon pressure-sensitive adhesive of the present invention comprises an alkenyl-containing polyorganosiloxane raw rubber, MQ silicone resin, an ionic liquid containing reactive double bonds, a hydrogen-containing silicone oil, an inhibitor 1-ethynyl-1-cyclohexanol, a platinum catalyst, and an organic solvent; wherein, by mass parts, the alkenyl-containing polyorganosiloxane raw rubber is 50 parts, the MQ silicone resin is 25 parts, the ionic liquid containing reactive double bonds is 4.57~15.36 parts, the hydrogen-containing silicone oil is 2.48~4.64 parts, the inhibitor 1-ethynyl-1-cyclohexanol is 0.06 parts, the platinum catalyst is 0.2 parts, and the organic solvent is 10~30 parts.

[0005] Furthermore, the alkenyl-containing polyorganosiloxane raw rubber is vinyl-terminated polydimethylsiloxane raw rubber, which is composed of one or more of the following: 5000 cP of vinyl silicone oil Vi-5000, 10000 cP of vinyl silicone oil Vi-10000, and 20000 cP of vinyl silicone oil Vi-20000.

[0006] Furthermore, the vinyl MQ silicone resin has an ethylene content of 2.6 wt%.

[0007] Furthermore, the ionic liquid containing reactive double bonds is one or more of 1-allyl-3-methylimidazolium diimide salt, 1-vinyl-3-butylimidazolium diimide salt, and 1-allyl-3-methylimidazolium hexafluorophosphate.

[0008] Furthermore, the hydrogen-containing silicone oil is one or more of H050 with a hydrogen content of 0.50 wt%, H075 with a hydrogen content of 0.75 wt%, and H100 with a hydrogen content of 1.00 wt%, used as a crosslinking agent, and the viscosity of each is 120 cP.

[0009] Furthermore, the platinum catalyst is a caster catalyst, wherein the platinum content is 5000 ppm, dissolved in 100 cP vinyl silicone oil.

[0010] The steps of the method for preparing an electro-debinding organosilicon pressure-sensitive adhesive based on a chemically bonded ionic liquid according to the present invention include: Step 1: Weigh out vinyl-terminated polydimethylsiloxane raw rubber, vinyl MQ silicone resin and inhibitor 1-ethynyl-1-cyclohexanol and place them in a reaction vessel. Then add toluene, an organic solvent, and stir to dissolve at room temperature. Step 2: Add the weighed ionic liquid containing reactive double bonds to the reaction vessel and continue stirring to form a homogeneous system; Step 3: Add hydrogen-containing silicone oil and platinum catalyst to the system, stir evenly, and then perform vacuum degassing to remove bubbles from the system. Step 4: Apply the degassed adhesive evenly to the substrate with the conductive layer, place it in an oven for heat curing, and allow it to undergo a hydrosilylation reaction. After cooling, allow it to mature at room temperature to obtain a chemically bonded electro-debonding silicone pressure-sensitive adhesive.

[0011] Furthermore, the stirring time in step 2 is 1 hour.

[0012] Furthermore, in step 4, the temperature in the oven is 120 ℃, the heat curing time is 1~3 min, and the room temperature curing time is 24 hours.

[0013] The beneficial effects of this invention are as follows: The method for preparing an electro-debonding silicone pressure-sensitive adhesive with chemically bonded ionic liquid provided by this invention, by introducing reactive ionic liquid to participate in curing and cross-linking, can simultaneously ensure high transparency (>90%) and good initial adhesion performance (>15 N / 25 mm) of the adhesive layer, effectively improving the common problems of "easy oil seepage and low initial tack" in physically blended electro-debonding tapes. By adjusting the type and grafting amount of ionic liquid, the electro-debonding response speed and peel force reduction rate of the silicone pressure-sensitive adhesive can be flexibly controlled (after applying a 30V voltage for 30 seconds, the peel force reduction rate can reach more than 80%).

[0014] Example Example 1: This embodiment discloses a method for preparing an electro-debonding silicone pressure-sensitive adhesive with chemically bonded ionic liquid. The selected components are as follows (by weight): 50 g of vinyl-terminated polydimethylsiloxane raw rubber Vi-5000, 25 g of vinyl MQ resin, 15.36 g of 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ([AMIM][TFSI], reactive ionic liquid), 4.64 g of hydrogen-containing silicone oil H050, 0.2 g of platinum catalyst, 0.06 g of 1-ethynyl-1-cyclohexanol, and 10 mL of toluene solvent.

[0015] The preparation method includes the following steps: Step 1: Weigh 50 g of vinyl-terminated polydimethylsiloxane raw rubber Vi-5000 and 25 g of vinyl MQ resin into a reaction vessel, add 0.06 g of the inhibitor 1-ethynyl-1-cyclohexanol, add 10 mL of toluene, and stir at room temperature for 30 min to dissolve evenly. Step 2: Add 15.36 g of [AMIM][TFSI] to the reaction vessel and continue stirring for 1 h to ensure it is fully dispersed in the system; Step 3: Add 4.64 g of hydrogen-containing silicone oil and 0.2 g of platinum catalyst to the system, stir for 15 min, and then place it in a vacuum degassing machine for 10 min to degas. Step 4: Apply the degassed adhesive evenly to the PET substrate with the aluminum thin layer using a coater, heat cure it in a 120℃ oven for 1 min, and then cure it at room temperature for 24 h to obtain a pressure-sensitive adhesive layer with a thickness of about 25 μm, which is named PSA-Vi5000.

[0016] Example 2: This embodiment discloses a method for preparing an electro-debonding silicone pressure-sensitive adhesive with chemically bonded ionic liquid. The selected components are as follows (by weight): 50 g of vinyl-terminated polydimethylsiloxane raw rubber Vi-10000, 25 g of vinyl MQ resin, 9.86 g of 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ([AMIM][TFSI], reactive ionic liquid), 3.27 g of hydrogen-containing silicone oil H075, 0.2 g of platinum catalyst (Pt complex), 0.06 g of 1-ethynyl-1-cyclohexanol, and 18 mL of toluene solvent.

[0017] The preparation method includes the following steps: Step 1: Weigh 50 g of vinyl raw gum and 25 g of vinyl MQ resin into a reaction vessel, add 0.06 g of the inhibitor 1-ethynyl-1-cyclohexanol, add 18 mL of toluene, and stir at room temperature for 30 min to dissolve evenly. Step 2: Add 9.86 g of [AMIM][TFSI] to the reaction vessel and continue stirring for 1 h to ensure it is fully dispersed in the system; Step 3: Add 3.27 g of hydrogen-containing silicone oil H075 and 0.2 g of platinum catalyst to the system, stir for 15 min, and then place it in a vacuum degassing machine for 10 min to degas. Step 4: Apply the degassed adhesive evenly to the PET substrate with the aluminum thin layer using a coater, heat cure it in a 120℃ oven for 2 min, and then cure it at room temperature for 24 h to obtain a pressure-sensitive adhesive layer with a thickness of about 25 μm, which is named PSA-Vi10000.

[0018] Example 3: This embodiment discloses a method for preparing an electro-debonding silicone pressure-sensitive adhesive with chemically bonded ionic liquid. The selected components are as follows (by weight): 50 g of vinyl-terminated polydimethylsiloxane raw rubber Vi-20000, 25 g of vinyl MQ resin, 4.57 g of 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt ([AMIM][TFSI], reactive ionic liquid), 2.48 g of hydrogen-containing silicone oil H100, 0.2 g of platinum catalyst (Pt complex), 0.06 g of 1-ethynyl-1-cyclohexanol, and 30 mL of toluene solvent.

[0019] The preparation method includes the following steps: Step 1: Weigh 50 g of vinyl raw gum and 25 g of vinyl MQ resin into a reaction vessel, add 0.06 g of the inhibitor 1-ethynyl-1-cyclohexanol, add 30 mL of toluene, and stir at room temperature for 30 min to dissolve evenly. Step 2: Add 4.57 g of [AMIM][TFSI] to the reaction vessel and continue stirring for 1 h to ensure it is fully dispersed in the system; Step 3: Add 2.18 g of hydrogen-containing silicone oil H100 and 0.2 g of platinum catalyst to the system, stir for 15 min, and then place it in a vacuum degassing machine for 10 min to degas. Step 4: Apply the degassed adhesive evenly to the PET substrate with the aluminum thin layer using a coater, heat cure it in a 120℃ oven for 3 min, and then cure it at room temperature for 24 h to obtain a pressure-sensitive adhesive layer with a thickness of about 25 μm, which is named PSA-Vi20000.

[0020] Example 4: This embodiment discloses a method for preparing an electro-debonding silicone pressure-sensitive adhesive with chemically bonded ionic liquids. The selected components by mass are as follows: 50 g of vinyl-terminated polydimethylsiloxane raw rubber Vi-10000, 25 g of vinyl MQ resin, 10.62 g of 1-vinyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide salt, 3.27 g of hydrogen-containing silicone oil, 0.2 g of platinum catalyst (Pt complex), 0.06 g of 1-ethynyl-1-cyclohexanol, and 18 mL of toluene solvent.

[0021] The preparation method includes the following steps: Step 1: Weigh 50 g of vinyl raw gum and 25 g of vinyl MQ resin into a reaction vessel, add 0.06 g of the inhibitor 1-ethynyl-1-cyclohexanol, add 18 mL of toluene, and stir at room temperature for 30 min to dissolve evenly. Step 2: Add 10.62 g of 1-vinyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imine salt to the reaction vessel and continue stirring for 1 h to ensure it is fully dispersed in the system; Step 3: Add 3.27 g of hydrogen-containing silicone oil and 0.2 g of platinum catalyst to the system, stir for 15 min, and then place it in a vacuum degassing machine for 10 min to degas. Step 4: Apply the degassed adhesive evenly to the PET substrate with the aluminum thin layer using a coater, heat cure in a 120℃ oven for 2 min, and then cure at room temperature for 24 h to obtain a pressure-sensitive adhesive layer with a thickness of about 25 μm, which is named PSA-NH.

[0022] Example 5: This embodiment discloses a method for preparing an electro-debonding silicone pressure-sensitive adhesive with chemically bonded ionic liquids. The selected components by mass are: 50 g of vinyl-terminated polydimethylsiloxane raw rubber Vi-10000, 25 g of vinyl MQ resin, 9.74 g of 1-allyl-3-methylimidazolium hexafluorophosphate, 3.27 g of hydrogen-containing silicone oil, 0.2 g of platinum catalyst (Pt complex), 0.06 g of 1-ethynyl-1-cyclohexanol, and 18 mL of toluene solvent.

[0023] The preparation method includes the following steps: Step 1: Weigh 50 g of vinyl raw gum and 25 g of vinyl MQ resin into a reaction vessel, add 0.06 g of the inhibitor 1-ethynyl-1-cyclohexanol, add 18 mL of toluene, and stir at room temperature for 30 min to dissolve evenly. Step 2: Add 9.74 g of 1-allyl-3-methylimidazolium hexafluorophosphate to the reaction vessel and continue stirring for 1 hour to ensure it is fully dispersed in the system; Step 3: Add 3.27 g of hydrogen-containing silicone oil and 0.2 g of platinum catalyst to the system, stir for 15 min, and then place it in a vacuum degassing machine for 10 min to degas. Step 4: Apply the degassed adhesive evenly to the PET substrate with the aluminum thin layer using a coater, heat cure in a 120℃ oven for 2 min, and then cure at room temperature for 24 h to obtain a pressure-sensitive adhesive layer with a thickness of about 25 μm, which is named PSA-P.

[0024] Comparative Example 1 (Physical Blend): This comparative example uses a conventional non-reactive ionic liquid for physical blending. The selected components are: 50 g of vinyl raw rubber Vi10000, 25 g of vinyl MQ resin, 9.86 g of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ([EMIM][TFSI], non-reactive ionic liquid), 3.27 g of hydrogen-containing silicone oil, 0.2 g of platinum catalyst, and 18 mL of toluene.

[0025] The preparation steps are the same as in Example 1. Since the ionic liquid has no double bonds and does not participate in the reaction, the system after curing is a physical blend structure, which is named Phy-PSA.

[0026] Comparative Example 2 (pure silicone): This comparative example does not contain any ionic liquids. The selected components consist of: 50 g of vinyl raw rubber Vi10000, 25 g of vinyl MQ resin, 3.27 g of hydrogen-containing silicone oil, 0.2 g of platinum catalyst, and 18 mL of toluene. The preparation procedure is the same as in Example 1, and it is named Blank-PSA.

[0027] The above-described embodiments and control examples underwent initial 180° peel force testing, peel force testing after electro-induced debonding, peel force reduction rate calculation, and appearance and precipitation observation. The test data are shown in the table below:

[0028] Test method description: 1. Initial 180° peel force: According to standard GB / T2792-2014, the cut 25 mm wide tape is attached to a standard stainless steel test plate, and rolled back and forth 3 times with a 2.5 kg standard pressure roller. After 20 min, the 180° peel test is performed using an electronic tensile testing machine at a speed of 300 mm / min.

[0029] 2. Electro-induced debonding test: Connect the aluminum foil layer on the back of the tape (as the cathode) adhered to the stainless steel test plate (as the anode) to a DC power supply, apply a 30V DC voltage for 30 seconds. Immediately after the power is applied, use an electronic tensile testing machine to test the peel force at the same speed and calculate the peel force reduction rate.

[0030] As can be seen from the results in the table above, Examples 1 to 3, which introduced ionic liquids through chemical bonding, maintained a transparent and non-precipitated adhesive layer after curing, with an initial peel force maintained at a high level of over 13 N / 25 mm. After applying a 30V voltage for 30 seconds, the peel force decreased significantly (the decrease rate in Example 2 reached as high as 85.7%), perfectly achieving a combination of highly reliable adhesion and intelligent electro-induced debonding. In contrast, Control Example 1, which involved physical blending, experienced severe phase separation and oil seepage, resulting in extremely low initial tack and rendering it unusable; Control Example 2 lacked electric field response capability. This invention provides a novel and highly efficient method for preparing organosilicon pressure-sensitive adhesives for non-destructive and reversible bonding of flexible devices.

[0031] Working principle This invention utilizes a platinum-catalyzed hydrosilylation reaction between an ionic liquid containing reactive double bonds (such as allyl or vinyl), vinyl organosilicon raw material, and hydrogen-containing polysiloxane. This reaction permanently covalently bonds the cationic or anionic framework of the ionic liquid to a three-dimensional organosilicon network, acting as side groups or crosslinking points. This chemical grafting method completely overcomes the phase separation problem, achieving "zero precipitation." Simultaneously, when a DC voltage is applied, free counterions rapidly migrate and accumulate towards the interface under the drive of the electric field, forming a strong double-layer polarization effect. This instantly disrupts the van der Waals forces and hydrogen bonds at the interface, leading to a sharp decrease in peel strength. Therefore, it combines high initial tack with excellent electro-induced debonding responsiveness.

[0032] 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 chemically bonded ionic liquid electro-debinding silicone pressure-sensitive adhesive, characterized in that, The product comprises alkenyl-containing polyorganosiloxane raw rubber, MQ silicone resin, ionic liquid containing reactive double bonds, hydrogen-containing silicone oil, inhibitor 1-ethynyl-1-cyclohexanol, platinum catalyst, and organic solvent; wherein, by mass parts, the product comprises 50 parts alkenyl-containing polyorganosiloxane raw rubber, 25 parts MQ silicone resin, 4.57~15.36 parts ionic liquid containing reactive double bonds, 2.48~4.64 parts hydrogen-containing silicone oil, 0.06 parts inhibitor 1-ethynyl-1-cyclohexanol, 0.2 parts platinum catalyst, and 10~30 parts organic solvent.

2. The electro-debonding silicone pressure-sensitive adhesive based on chemically bonded ionic liquids according to claim 1, characterized in that, The alkenyl-containing polyorganosiloxane raw rubber is a vinyl-terminated polydimethylsiloxane raw rubber, which is composed of one or more of the following: 5000 cP of vinyl silicone oil Vi-5000, 10000 cP of vinyl silicone oil Vi-10000, and 20000 cP of vinyl silicone oil Vi-20000.

3. The electro-debonding silicone pressure-sensitive adhesive based on chemically bonded ionic liquids according to claim 1, characterized in that, The vinyl MQ silicone resin has an ethylene content of 2.6 wt%.

4. The electro-debonding silicone pressure-sensitive adhesive with chemically bonded ionic liquid according to claim 1, characterized in that, Ionic liquids containing reactive double bonds are one or more of 1-allyl-3-methylimidazolium diimide salt, 1-vinyl-3-butylimidazolium diimide salt, and 1-allyl-3-methylimidazolium hexafluorophosphate.

5. The electro-debonding silicone pressure-sensitive adhesive for chemically bonded ionic liquids according to claim 1, characterized in that, The hydrogen-containing silicone oil is one or more of H050 with a hydrogen content of 0.50 wt%, H075 with a hydrogen content of 0.75 wt%, and H100 with a hydrogen content of 1.00 wt%, which are used as crosslinking agents, and the viscosity of each is 120 cP.

6. The electro-debonding silicone pressure-sensitive adhesive for chemically bonded ionic liquids according to claim 1, characterized in that, The platinum catalyst is a caster catalyst, in which the platinum content is 5000 ppm and dissolved in 100 cP of vinyl silicone oil.

7. A method for preparing the pressure-sensitive adhesive according to any one of claims 1 to 6, characterized in that, The specific steps include: Step 1: Weigh out vinyl-terminated polydimethylsiloxane raw rubber, vinyl MQ silicone resin and inhibitor 1-ethynyl-1-cyclohexanol and place them in a reaction vessel. Then add toluene, an organic solvent, and stir to dissolve at room temperature. Step 2: Add the weighed ionic liquid containing reactive double bonds to the reaction vessel and continue stirring to form a homogeneous system; Step 3: Add hydrogen-containing silicone oil and platinum catalyst to the system, stir evenly, and then perform vacuum degassing to remove bubbles from the system. Step 4: Apply the degassed adhesive evenly to the substrate with the conductive layer, place it in an oven for heat curing, and allow it to undergo a hydrosilylation reaction. After cooling, allow it to mature at room temperature to obtain a chemically bonded electro-debonding silicone pressure-sensitive adhesive.

8. The method for preparing an electro-debonding organosilicon pressure-sensitive adhesive based on a chemically bonded ionic liquid according to claim 7, characterized in that, The stirring time in step 2 is 1 hour.

9. The method for preparing an electro-debonding organosilicon pressure-sensitive adhesive based on a chemically bonded ionic liquid according to claim 7, characterized in that, In step 4, the temperature in the oven is 120 ℃, the heat curing time is 1~3 min, and the room temperature curing time is 24 hours.

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