Hydrophobic adhesive tape and preparation method thereof

Abstract

The invention discloses a hydrophobic adhesive tape, which relates to the technical field of adhesive tapes and comprises a base film layer, a hydrophobic layer and an adhesive layer, the hydrophobic layer is prepared from the following components: 70%-80% of fluorine-containing acrylic resin, 5%-8% of nano silicon dioxide, 3%-5% of epoxy functional silane and the balance of a solvent, and the adhesive layer is prepared from the following components: 50%-60% of a silicone rubber matrix, 10%-20% of polyurethane acrylate, 5%-10% of a hydroxyl functional monomer, 2%-5% of hydrophobic silicon dioxide, 1%-3% of an auxiliary agent and the balance of a solvent. The fluorine-containing acrylic resin is used as a main body of the hydrophobic layer, so that the hydrophobic layer has extremely low surface energy and has a relatively strong hydrophobic effect; the nano silicon dioxide in the hydrophobic layer can generate a micro-nano coarse structure, so that the self-cleaning effect of the hydrophobic layer is enhanced; the epoxy functional silane in the hydrophobic layer and the hydroxyl functional monomer in the adhesive layer can form a new chemical bond when the adhesive tape is attached in a surrounding manner, and a sealing barrier is formed at an interface to prevent moisture from permeating.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesive tapes, and in particular to a hydrophobic adhesive tape and a preparation method thereof. Background Art

[0002] With the increasing demand for waterproofing, sealing, and weather resistance in electronic products and energy storage devices, adhesive tapes are increasingly being used in battery packaging, connection, and sealing applications. Existing technologies often use polyethylene (PE) film as a base film, with fluoride, silane compounds, and silicones used as a hydrophobic layer on the base film, and acrylic adhesives used as the adhesive layer to achieve hydrophobic properties. However, traditional hydrophobic adhesive tapes typically only have a hydrophobic effect on the back side, resulting in the possibility of moisture intrusion through gaps in the tape when applied to an object. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a hydrophobic adhesive tape and a preparation method, the specific technical solution is as follows:

[0004] A hydrophobic adhesive tape comprises a base film layer, a hydrophobic layer coated on the outside of the base film layer, and an adhesive layer coated on the inside of the base film layer, wherein the base film layer is a PET or PI film; the hydrophobic layer comprises the following components by weight: 70% to 80% of a fluorine-containing acrylic resin, 5% to 8% of nano-silicon dioxide, 3% to 5% of an epoxy-functional silane, and the balance being a solvent; the adhesive layer comprises the following components: 50% to 60% of a silicone rubber matrix, 10% to 20% of a polyurethane acrylate, 5% to 10% of a hydroxyl-functional monomer, 2% to 5% of hydrophobic silicon dioxide, 1% to 3% of an additive, and the balance being a solvent, wherein the additive comprises at least one of a cross-linking agent and a catalyst.

[0005] Preferably:

[0006] The thickness of the base film layer is 25 to 50 μm;

[0007] The thickness of the hydrophobic layer is 1 to 3 μm;

[0008] The thickness of the adhesive layer is 20 to 50 μm.

[0009] Preferably:

[0010] The epoxy functional silane is 3-(2,3-epoxypropoxy)propyltrimethoxysilane;

[0011] The silicone rubber matrix is PDMS or silicone acrylic copolymer;

[0012] The cross-linking agent is an organic peroxide;

[0013] The catalyst is a platinum catalyst.

[0014] The present invention also provides a preparation method for preparing the hydrophobic adhesive tape as described above, comprising the following steps:

[0015] Step 1: Pretreatment of the base film layer: Use ultrasonic cleaning or solvent to wipe the surface of the base film layer, and then dry it to remove surface moisture through Corona discharge or plasma treatment;

[0016] Step 2, preparation of hydrophobic layer: weigh fluorinated acrylic resin, nano-silica, epoxy functional silane and solvent in proportion, and place them in a stirring tank in sequence. After high shear mixing and ultrasonic dispersion, use a slot die, scraper or roller coating method to evenly coat one side of the base film layer. After coating, put it into an oven, set the temperature to 80-120°C, and bake for 10-30 minutes;

[0017] Step 3, adhesive layer preparation: In an inert environment, mix the silicone rubber matrix, polyurethane acrylate, hydroxyl functional monomer, hydrophobic silica, additives and solvent in proportion, stir evenly to ensure the consistency of the system, and then evenly apply it on the other side of the base film using a scraper or roller coating method. After coating, pre-cure at 40-60°C for 5-10 minutes.

[0018] Preferably, the nano-silica in step 2 is nano-silica surface-modified with long-chain fluorosilane, and the preparation process of the nano-silica surface-modified with long-chain fluorosilane specifically comprises the following steps:

[0019] The nano-silica was placed in a vacuum oven, dried at 110-120° C. for 2-3 hours to remove surface moisture, and then dispersed in anhydrous toluene. Ultrasonic and mechanical stirring was used for 30-60 minutes to obtain a first dispersion.

[0020] Add trifluoroacetic acid dropwise to the first dispersion to adjust the pH of the dispersion to 4-5;

[0021] Slowly add the long-chain fluorosilane to the first dispersion while stirring continuously to ensure uniform distribution;

[0022] Under an inert atmosphere, heat the dispersed system to 80-110°C and reflux for 4-6 hours;

[0023] After the reaction is completed, the mixture is naturally cooled to room temperature and the modified nano-silica is separated by centrifugation;

[0024] The separated modified nano-silica is washed with anhydrous hexane and then washed with anhydrous ethanol. The modified nano-silica is then dried in a vacuum oven at 80-100° C. for 2-4 hours to obtain the product.

[0025] Preferably:

[0026] The addition amount of the long-chain fluorosilane is 2% to 5% of the mass of the nano-silicon dioxide;

[0027] The long-chain fluorosilane is 1H,1H,2H,2H-perfluorooctyltriethoxysilane.

[0028] Preferably, the silicone rubber matrix is PDMS grafted with hydroxyl side chains or PDMS grafted with amine side chains.

[0029] Preferably, the preparation process of the PDMS grafted with hydroxyl side chains specifically includes the following steps:

[0030] Dissolve the Si-H functionalized PDMS in an anhydrous solvent, maintain the temperature and stir evenly to obtain a mixed solution A;

[0031] Adding protected allyl alcohol and platinum catalyst to mixed solution A and stirring evenly, wherein the added amount of protected allyl alcohol is 5% to 10% of the mass of PDMS, and the added amount of platinum catalyst is 0.01% to 0.05% of the mass of PDMS;

[0032] Under an inert atmosphere, the mixed solution A is heated to 60-70° C., reacted for 4-6 hours, and then deprotected using an acid or base. Subsequently, unreacted small molecules and catalyst residues are removed by precipitation or extraction, and then dried in a vacuum oven at 80-100° C. for 2-4 hours.

[0033] Preferably, the preparation process of the PDMS grafted with amino side chains specifically includes the following steps:

[0034] Dissolve the Si-H functionalized PDMS in an anhydrous solvent, maintain the temperature and stir evenly to obtain a mixed solution B;

[0035] Adding protected allylamine and platinum catalyst to mixed solution B and stirring evenly, wherein the amount of protected allylamine added is 5% to 10% of the mass of PDMS, and the amount of platinum catalyst added is 0.01% to 0.05% of the mass of PDMS;

[0036] Under an inert atmosphere, the mixed solution B is heated to 60-70° C., reacted for 4-6 hours, and then deprotected using trifluoroacetic acid. Subsequently, unreacted small molecules and catalyst residues are removed by precipitation or extraction, and then dried in a vacuum oven at 80-100° C. for 2-4 hours.

[0037] Preferably, the hydrophobic silica is silica grafted on the surface of a PDMS-based silane coupling agent. The preparation process of the silica grafted on the surface of a PDMS-based silane coupling agent specifically comprises the following steps:

[0038] Place the silica in a vacuum oven and dry it at 110-120°C for 2-3 hours to remove surface moisture;

[0039] Dispersing the dried silica in anhydrous toluene at a concentration of 5 to 10 wt%, and stirring with ultrasound and mechanical stirring for 30 to 60 minutes to obtain a second dispersion;

[0040] Slowly add the PDMS silane coupling agent dropwise to the second dispersion, stirring continuously while adding to ensure uniform distribution;

[0041] Under an inert atmosphere, heat the dispersed system to 80-110°C and reflux for 4-6 hours;

[0042] After the reaction is completed, the mixture is naturally cooled to room temperature and the surface-grafted silica is separated by centrifugation;

[0043] The separated surface-grafted silica is washed 2 to 3 times with anhydrous toluene, and then dried in a vacuum oven at 80 to 100° C. for 2 to 4 hours.

[0044] The hydrophobic adhesive tape provided by the present invention has the following beneficial effects:

[0045] 1. By using fluorinated acrylic resin as the main body of the hydrophobic layer on the outside of the hydrophobic adhesive tape, the hydrophobic layer has extremely low surface energy, which can reduce the adhesion of aqueous substances and has a strong hydrophobic effect;

[0046] 2. Nano-silica in the hydrophobic layer can produce a micro-nano rough structure, thereby enhancing the self-cleaning effect of the hydrophobic layer;

[0047] 3. The epoxy functional silane in the hydrophobic layer and the hydroxyl functional monomer in the adhesive layer can form new chemical bonds when the adhesive tape is attached around it, thereby forming a sealing barrier at the interface to prevent moisture from penetrating. DETAILED DESCRIPTION

[0048] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0049] This embodiment provides a hydrophobic adhesive tape, comprising a base film layer, a hydrophobic layer coated on the outside of the base film layer, and an adhesive layer coated on the inside of the base film layer, wherein the base film layer is a PET or PI film; the hydrophobic layer comprises the following components, by weight percentage: 70% to 80% of a fluorine-containing acrylic resin, 5% to 8% of nano-silica, 3% to 5% of an epoxy-functional silane, and the balance being a solvent; the adhesive layer comprises the following components: 50% to 60% of a silicone rubber matrix, 10% to 20% of a polyurethane acrylate, 5% to 10% of a hydroxyl-functional monomer, 2% to 5% of hydrophobic silica, 1% to 3% of an additive, and the balance being a solvent, wherein the additive comprises at least one of a cross-linking agent and a catalyst.

[0050] Among them, PET or PI film can provide the mechanical strength and dimensional stability of the adhesive tape; the hydrophobic layer made mainly of fluorine-containing acrylic resin has extremely low surface energy (target water contact angle >110°), thus having a strong hydrophobic effect, and nano-silica can produce a micro-nano rough structure, thereby enhancing the self-cleaning effect of the hydrophobic layer; the mixture of silicone rubber matrix and polyurethane acrylate in the adhesive layer helps to improve the polarity and interfacial bonding of the adhesive layer, thereby increasing the interfacial adhesion between the adhesive layer and the attached object, and hydrophobic silica can improve the rheological properties without significantly reducing the adhesion performance of the adhesive layer.

[0051] When the adhesive tape is attached around the surface, the hydrophobic layer and the adhesive layer come into contact. Under the action of pressure or temperature, the epoxy-functional silane in the hydrophobic layer and the hydroxyl-functional monomer in the adhesive layer form new chemical bonds, thereby forming a sealing barrier at the interface to prevent moisture from penetrating.

[0052] The hydrophobic adhesive tape provided in this embodiment has the following beneficial effects:

[0053] 1. By using fluorinated acrylic resin as the main body of the hydrophobic layer on the outside of the hydrophobic adhesive tape, the hydrophobic layer has extremely low surface energy, which can reduce the adhesion of aqueous substances and has a strong hydrophobic effect;

[0054] 2. Nano-silica in the hydrophobic layer can produce a micro-nano rough structure, thereby enhancing the self-cleaning effect of the hydrophobic layer;

[0055] 3. The epoxy functional silane in the hydrophobic layer and the hydroxyl functional monomer in the adhesive layer can form new chemical bonds when the adhesive tape is attached around it, thereby forming a sealing barrier at the interface to prevent moisture from penetrating.

[0056] Further:

[0057] The thickness of the base film layer is 25 to 50 μm.

[0058] The thickness of the hydrophobic layer is 1 to 3 μm.

[0059] The thickness of the adhesive layer is 20 to 50 μm.

[0060] Further:

[0061] The epoxy-functional silane is 3-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0062] The silicone rubber matrix is PDMS or silicone acrylic copolymer.

[0063] The crosslinking agent is an organic peroxide.

[0064] The catalyst is a platinum catalyst.

[0065] This embodiment further provides a preparation method for preparing the hydrophobic adhesive tape as described in any one of the above, the preparation method comprising the following steps:

[0066] Step 1: Pretreatment of the base film layer: Use ultrasonic cleaning or solvent to wipe the surface of the base film layer, and dry it after Corona discharge or plasma treatment to remove surface moisture.

[0067] Step 2, preparation of hydrophobic layer: weigh fluorine-containing acrylic resin, nano-silica, epoxy functional silane and solvent in proportion, and put them into a stirring tank in sequence. After high shear mixing and ultrasonic dispersion, use a slot die, scraper or roller coating method to evenly coat one side of the base film layer. After coating, put it into the oven, set the temperature to 80-120℃, and bake for 10-30 minutes.

[0068] Step 3, adhesive layer preparation: In an inert environment, mix the silicone rubber matrix, polyurethane acrylate, hydroxyl functional monomer, hydrophobic silica, additives and solvent in proportion, stir evenly to ensure the consistency of the system, and then evenly apply it on the other side of the base film using a scraper or roller coating method. After coating, pre-cure at 40-60°C for 5-10 minutes.

[0069] Furthermore, the nano-silica in step 2 is nano-silica surface-modified with long-chain fluorosilane, and the preparation process of the nano-silica surface-modified with long-chain fluorosilane specifically includes the following steps:

[0070] The nano-silica was placed in a vacuum oven, dried at 110-120° C. for 2-3 hours to remove surface moisture, and then dispersed in anhydrous toluene. Ultrasonic and mechanical stirring was used for 30-60 minutes to obtain a first dispersion.

[0071] Trifluoroacetic acid was added dropwise to the first dispersion to adjust the pH of the dispersion system to 4-5.

[0072] Slowly add the long-chain fluorosilane dropwise to the first dispersion while stirring continuously to ensure uniform distribution.

[0073] Under an inert atmosphere, heat the dispersed system to 80-110°C and reflux for 4-6 hours.

[0074] After the reaction is completed, the mixture is naturally cooled to room temperature and the modified nano-silica is separated by centrifugation.

[0075] The separated modified nano-silica is washed with anhydrous hexane and then washed with anhydrous ethanol. The modified nano-silica is then dried in a vacuum oven at 80-100° C. for 2-4 hours to obtain the product.

[0076] The modification principle is: during the reaction, the alkoxy group of fluorosilane hydrolyzes to form silanol, which undergoes a condensation reaction with the hydroxyl group on the surface of nano-silica to form a stable Si-O-Si bond. At the same time, the hydrophobic perfluorooctyl chain is grafted to the surface to jointly construct a coating with low surface energy and excellent stain resistance, thereby providing higher hydrophobicity and self-cleaning effect.

[0077] Further:

[0078] The addition amount of the long-chain fluorosilane is 2% to 5% of the mass of the nano-silicon dioxide.

[0079] The long-chain fluorosilane is 1H,1H,2H,2H-perfluorooctyltriethoxysilane.

[0080] Furthermore, the silicone rubber matrix is PDMS grafted with hydroxyl side chains or PDMS grafted with amine side chains.

[0081] Furthermore, the preparation process of PDMS grafted with hydroxyl side chains specifically includes the following steps:

[0082] Dissolve the Si-H functional PDMS in an anhydrous solvent, maintain the temperature and stir evenly to obtain a mixed solution A.

[0083] Add protected allyl alcohol and platinum catalyst to mixed solution A and stir evenly, wherein the added amount of protected allyl alcohol is 5% to 10% of the mass of PDMS, and the added amount of platinum catalyst is 0.01% to 0.05% of the mass of PDMS.

[0084] Under an inert atmosphere, the mixed solution A is heated to 60-70° C., reacted for 4-6 hours, and then deprotected using an acid or base. Subsequently, unreacted small molecules and catalyst residues are removed by precipitation or extraction, and then dried in a vacuum oven at 80-100° C. for 2-4 hours.

[0085] The modification principle involves introducing protected hydroxyl groups onto PDMS side chains through a hydrosilane addition reaction between the Si-H groups in PDMS and an allyl derivative. These groups are then deprotected to yield free hydroxyl groups. The modified PDMS possesses more free hydroxyl groups, which not only enhances adhesion between the adhesive layer and the surface being adhered, but also facilitates crosslinking with the epoxy silane in the inner adhesive layer, forming a strong chemical bond.

[0086] Furthermore, the preparation process of PDMS grafted with amino side chains specifically includes the following steps:

[0087] Dissolve the Si-H functional PDMS in an anhydrous solvent, maintain the temperature and stir evenly to obtain a mixed solution B.

[0088] Add protected allylamine and platinum catalyst to mixed solution B and stir evenly, wherein the added amount of protected allylamine is 5% to 10% of the mass of PDMS, and the added amount of platinum catalyst is 0.01% to 0.05% of the mass of PDMS.

[0089] Under an inert atmosphere, the mixed solution B is heated to 60-70° C., reacted for 4-6 hours, and then deprotected using trifluoroacetic acid. Subsequently, unreacted small molecules and catalyst residues are removed by precipitation or extraction, and then dried in a vacuum oven at 80-100° C. for 2-4 hours.

[0090] The modification principle is: introducing amino side chains on the PDMS chain so that the molecule contains free amino groups. The amino groups have high nucleophilicity, which can not only improve the adhesion of the adhesive layer, but also cooperate with the hydroxyl functional monomer inside the adhesive layer, making it easier to react with the external epoxy silane to form a strong interfacial chemical bond.

[0091] Furthermore, the hydrophobic silica is silica grafted on the surface of a PDMS-based silane coupling agent. The preparation process of silica grafted on the surface of a PDMS-based silane coupling agent specifically includes the following steps:

[0092] Place the silica in a vacuum oven and dry it at 110-120°C for 2-3 hours to remove surface moisture.

[0093] The dried silicon dioxide is dispersed in anhydrous toluene at a concentration of 5 to 10 wt %, and ultrasonic and mechanical stirring are used for 30 to 60 minutes to obtain a second dispersion.

[0094] Slowly add the PDMS silane coupling agent dropwise to the second dispersion while stirring continuously to ensure uniform distribution.

[0095] Under an inert atmosphere, heat the dispersed system to 80-110°C and reflux for 4-6 hours.

[0096] After the reaction is completed, the mixture is naturally cooled to room temperature and the surface-grafted silica is separated by centrifugation.

[0097] The separated surface-grafted silica is washed 2 to 3 times with anhydrous toluene, and then dried in a vacuum oven at 80 to 100° C. for 2 to 4 hours.

[0098] The modification principle involves grafting a PDMS-based silane coupling agent onto the hydrophobic silica surface. After grafting, the silica particles are coated with a layer of flexible PDMS segments, which not only further enhances their compatibility with the PDMS and polyurethane acrylate in the adhesive layer but also allows for precise control of the dispersion state by controlling the grafting density, thereby achieving precise regulation of rheological properties.

[0099] Specific examples are provided below. The provided examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0100] Example 1

[0101] Base film pretreatment:

[0102] Place the PET film in an ultrasonic cleaner using anhydrous ethanol for 5 minutes to remove surface dust and oil. Use a clean cloth or airflow to dry any residual solvent. Place the cleaned film in a Corona discharge device for approximately 30 seconds to increase the surface hydrophilicity and facilitate subsequent coating adhesion. Place the film in an oven preheated to 120°C and dry for 10 minutes to ensure the surface is free of moisture.

[0103] Preparation of hydrophobic layer:

[0104] Weigh the following components in proportion: 75.0g of fluorinated acrylic resin, 6.0g of nanosilica, 4.0g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, and 15.0g of anhydrous toluene. Add each component sequentially to a high-shear mixer. Use high-shear stirring for 10 minutes to ensure uniform dispersion of the components; then place the mixture in an ultrasonic disperser for another 10 minutes to fully disperse the nanosilica. Use a knife coater to evenly apply the hydrophobic coating to the outside of the PET base film, with a target dry film thickness of approximately 2μm. Place the coated base film in an oven preheated to 100°C and bake for 15 minutes to ensure solvent evaporation and sufficient curing of the coating.

[0105] Adhesive layer preparation:

[0106] In a nitrogen-filled environment, weigh the following components: 55.0g PDMS, 15.0g polyurethane acrylate, 8.0g allyl alcohol, 3.0g hydrophobic silica, 1.5g cyclohexanone peroxide, and 17.5g anhydrous toluene. Place all components in a high-shear mixer. Stir for 15 minutes under nitrogen to ensure a uniform and bubble-free system. Apply the adhesive layer evenly to the inner side of the base film using a roller, aiming for a dry film thickness of approximately 30μm.

[0107] The coated base film is placed in a temperature-controlled device and pre-cured at 50°C for 8 minutes to obtain a preliminary curing state to ensure good adhesion during subsequent lamination.

[0108] Example 2

[0109] The only difference between this embodiment and embodiment 1 is that the nano-silica in the hydrophobic layer is nano-silica surface-modified with long-chain fluorosilane. In this embodiment, the long-chain fluorosilane is 1H,1H,2H,2H-perfluorooctyltriethoxysilane. The preparation steps of the nano-silica surface-modified with long-chain fluorosilane are as follows:

[0110] Evenly spread 10.0 g of nano-silica on a heat-resistant tray and place in a vacuum oven. Set the temperature to 115°C and dry for 2.5 hours to completely remove surface moisture. Transfer the dried nano-silica to a 500 mL round-bottom flask and add 200 mL of anhydrous toluene. Start an ultrasonic disperser and stirrer, stirring for 45 minutes until a uniform dispersion is obtained. With continuous stirring, slowly add approximately 0.5 mL of 0.1 M trifluoroacetic acid solution using a dropper, monitoring the pH with a pH meter to adjust the dispersion to approximately 4.5. With continuous stirring, slowly add 0.3 g of 1H,1H,2H,2H-perfluorooctyltriethoxysilane dropwise. After ensuring the modifier is evenly dispersed in the dispersion, continue stirring for approximately 5 minutes to ensure thorough mixing before the reaction. Place the flask in a reflux apparatus and fill it with nitrogen to provide an inert atmosphere. Adjust the temperature to 90°C and maintain reflux for 5 hours, stirring continuously to ensure the reaction proceeds fully. After the reaction is completed, let the flask cool naturally to room temperature. Transfer the reaction solution to a centrifuge tube and centrifuge at about 5000rpm for 10 minutes to separate the modified nano-silica precipitate. Wash the centrifuged precipitate with 100mL of anhydrous hexane, repeat twice to remove unreacted silane and impurities. Then wash it once with 50mL of anhydrous ethanol to further clean the precipitate. Collect the washed precipitate and place it in a vacuum oven. Set the temperature to 90℃ and dry for 3 hours until the residual solvent is completely removed to obtain dry modified nano-silica powder.

[0111] The remaining components and process steps are the same as in Example 1.

[0112] Example 3

[0113] The only difference between this embodiment and embodiment 1 is that the silicone rubber matrix is PDMS grafted with hydroxyl side chains, and the preparation steps are as follows:

[0114] To a 250 mL three-necked flask, add 50.0 g of hydrogenated silicone rubber and 100 mL of anhydrous toluene. Stir thoroughly at room temperature using a mechanical stirrer to completely dissolve the PDMS, resulting in a uniform mixed solution A. Add 3.75 g of trityl ether to solution A and continue stirring until uniform. Next, add 0.01 g of platinum dioxide. After mixing, ensure uniform dispersion and no significant localized overconcentration. Connect the flask to a nitrogen line to exclude air and ensure the reaction is carried out under an inert atmosphere. Heat mixed solution A to 65°C and maintain this temperature for 5 hours. Stir continuously to ensure uniform grafting of the trityl ether onto the PDMS chains via the hydrosilane addition reaction. After the reaction is complete, cool the flask to room temperature and slowly add 0.5 mL of trifluoroacetic acid (TFA) dropwise under an inert atmosphere as a deprotection agent to promote the removal of the protecting groups in the trityl ether, generating free hydroxyl side chains. Continue stirring for 30 minutes after adding the acid to ensure complete deprotection. The reaction mixture was poured into 200 mL of anhydrous diethyl ether to precipitate the modified PDMS. The precipitate was collected using a centrifuge and then washed twice with anhydrous diethyl ether to remove unreacted small molecules and residual catalyst. The washed precipitate was dried in a vacuum oven at 90°C for 3 hours to obtain a dry PDMS powder grafted with hydroxyl side chains.

[0115] The remaining components and process steps are the same as in Example 1.

[0116] Example 4

[0117] The only difference between this embodiment and embodiment 1 is that the silicone rubber matrix is PDMS grafted with amino side chains, and the preparation steps are as follows:

[0118] To a 250 mL three-necked flask, add 50.0 g of hydrogenated silicone rubber and 100 mL of anhydrous toluene. Stir thoroughly at room temperature using a mechanical stirrer to completely dissolve the PDMS, forming a homogeneous mixed solution B. Add 3.75 g of N-Boc-allylamine to mixed solution B, stirring constantly to ensure uniform mixing. Then, add 0.01 g of platinum dioxide and continue stirring for 5 minutes to ensure even dispersion of the catalyst. Connect the flask to a nitrogen line to exclude air and ensure the reaction is carried out under an inert atmosphere. Heat the reaction system to 65°C and maintain the temperature for 5 hours. Maintain sufficient stirring during this time to ensure uniform hydrosilane addition reaction between the protected allylamine and the Si–H groups in the PDMS. After the reaction, cool the mixture to room temperature. Then, slowly add 0.5 mL of trifluoroacetic acid (TFA) dropwise under an inert atmosphere to remove the Boc protecting groups, generating free amine side chains. Continue stirring for 30 minutes after the addition of the acid to ensure complete deprotection. Pour the reaction mixture into 200 mL of anhydrous diethyl ether to precipitate the modified PDMS. Collect the precipitate using a filter or centrifuge and wash it twice with anhydrous diethyl ether to further remove unreacted small molecules and catalyst residues. After washing, collect the precipitate and place it in a vacuum oven set to 90°C. Dry it for 3 hours until all solvent has evaporated, yielding a dry solid of PDMS grafted with amino side chains.

[0119] The remaining components and process steps are the same as in Example 1.

[0120] Example 5

[0121] The only difference between this embodiment and embodiment 1 is that the hydrophobic silica in the adhesive layer is silica grafted on the surface of a PDMS-based silane coupling agent, and its preparation steps are as follows:

[0122] Evenly spread 10.0 g of silica on a heat-resistant tray and place it in a vacuum oven. Set the temperature to 115°C and dry for 2.5 hours to ensure complete removal of surface moisture. Transfer the dried silica to a 500 mL round-bottom flask and add 190 g of anhydrous toluene. Use an ultrasonic disperser combined with a mechanical stirrer for approximately 45 minutes until a uniform and stable 5 wt% dispersion is obtained. While stirring continuously, slowly add 0.3 g of a PDMS-based silane coupling agent to the second dispersion using a dropper. Maintain stirring during the addition to ensure uniform distribution of the silane coupling agent throughout the dispersion. Connect the flask to a reflux system and introduce nitrogen to establish an inert atmosphere. Adjust the reaction temperature to 90°C and allow the reaction to reflux for 5 hours. Continuously stir during this period to ensure that the PDMS silane coupling agent is fully hydrolyzed and undergoes a condensation reaction with the silica surface, forming stable Si—O—Si bonds and completing the grafting of the PDMS segments. After the reaction is complete, allow the system to cool naturally to room temperature. Transfer the reaction mixture to a centrifuge tube and centrifuge at approximately 5000 rpm for 10 minutes to separate the grafted silica precipitate. Wash the collected precipitate twice with approximately 50 mL of anhydrous toluene to ensure removal of unreacted silane coupling agent and impurities. Collect the precipitate after washing and remove excess solvent. Place the washed precipitate in a vacuum oven at 90°C and dry for 3 hours until dry PDMS-grafted silica powder is obtained.

[0123] The remaining components and process steps are the same as in Example 1.

[0124] Comparative Example

[0125] Ordinary hydrophobic adhesive tape (3M TM VHB TM 5906, 3M Company)

[0126] The hydrophobic adhesive tapes prepared in Examples 1 to 5 and the hydrophobic adhesive tapes of the comparative example were subjected to the following tests:

[0127] 1. Hydrophobicity test

[0128] Contact angle test: Test the contact angle of pure water droplets and take the average value of 5 points.

[0129] Rolling angle test: measures the angle at which a water drop rolls off a 45° inclined surface.

[0130] 2. Waterproof performance test

[0131] Humidity environment test (constant temperature and humidity chamber): aging at 85°C, 85% RH for 168 hours to observe whether the adhesive layer is affected by moisture.

[0132] Water immersion test (immersion in deionized water): Soak at a constant temperature of 40°C for 24 hours to test the change in adhesion.

[0133] 3. Adhesion test

[0134] 180° peel strength test: Test the initial adhesion and adhesion after aging at a peel rate of 50 mm / min.

[0135] The test results are shown in the following table:

[0136]

[0137] It can be seen that the modified nano-silica (Example 2) improves the hydrophobicity; the PDMS grafting modification (Examples 3 and 4) enhances the adhesion and aging resistance; the modified silica (Example 5) optimizes the rheological properties and has the best adhesion; the hydrophobic adhesive tape provided in this embodiment (Examples 1 to 5) has stronger adhesion and better hydrophobicity under humidity and water immersion conditions than the ordinary hydrophobic adhesive tape (Comparative Example).

[0138] The principles and implementation methods of the present invention are described herein using specific examples. The description of the above embodiments is only intended to help understand the method and core ideas of the present invention. The above are only preferred implementation methods of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, and all of these should fall within the scope of protection of the present invention.

Claims

1. A hydrophobic adhesive tape, characterized in that: The invention comprises a base film layer, a hydrophobic layer coated on the outside of the base film layer, and an adhesive layer coated on the inside of the base film layer, wherein the base film layer is a PET or PI film; the hydrophobic layer comprises the following components by weight: 70% to 80% of a fluorine-containing acrylic resin, 5% to 8% of nano-silica, 3% to 5% of an epoxy functional silane, and the balance being a solvent; the adhesive layer comprises the following components: 50% to 60% of a silicone rubber matrix, 10% to 20% of a polyurethane acrylate, 5% to 10% of a hydroxyl functional monomer, 2% to 5% of hydrophobic silica, 1% to 3% of an auxiliary agent, and the balance being a solvent, wherein the auxiliary agent comprises at least one of a cross-linking agent and a catalyst.

2. The hydrophobic adhesive tape according to claim 1, wherein: The thickness of the base film layer is 25 to 50 μm; The thickness of the hydrophobic layer is 1 to 3 μm; The thickness of the adhesive layer is 20 to 50 μm.

3. The hydrophobic adhesive tape according to claim 1, wherein: The epoxy functional silane is 3-(2,3-epoxypropoxy)propyltrimethoxysilane; The silicone rubber matrix is PDMS or silicone acrylic copolymer; The cross-linking agent is an organic peroxide; The catalyst is a platinum catalyst.

4. A preparation method, characterized in that: For preparing the hydrophobic adhesive tape according to any one of claims 1 to 3, the preparation method comprises the following steps: S1. Pretreatment of the base film layer: Use ultrasonic cleaning or solvent to wipe the surface of the base film layer, and then dry it to remove surface moisture through Corona discharge or plasma treatment; S2. Preparation of hydrophobic layer: Weigh fluorine-containing acrylic resin, nano-silica, epoxy-functional silane and solvent in proportion and place them in a stirring tank in sequence. After high shear mixing and ultrasonic dispersion, use a slot die, scraper or roller coating method to evenly apply them on one side of the base film layer. After coating, place the coating in an oven at 80-120°C and bake for 10-30 minutes. S3. Preparation of adhesive layer: In an inert environment, mix the silicone rubber matrix, polyurethane acrylate, hydroxyl functional monomer, hydrophobic silica, additives and solvent in proportion and stir evenly to ensure the consistency of the system. Then, apply it evenly on the other side of the base film using a scraper or roller coating method. After coating, pre-cure it at 40-60°C for 5-10 minutes.

5. The preparation method according to claim 4, characterized in that The nano-silica in step S2 is nano-silica surface-modified with long-chain fluorosilane. The preparation process of the nano-silica surface-modified with long-chain fluorosilane specifically includes the following steps: The nano-silica was placed in a vacuum oven, dried at 110-120° C. for 2-3 hours to remove surface moisture, and then dispersed in anhydrous toluene. Ultrasonic and mechanical stirring was used for 30-60 minutes to obtain a first dispersion. Add trifluoroacetic acid dropwise to the first dispersion to adjust the pH of the dispersion to 4-5; Slowly add the long-chain fluorosilane to the first dispersion while stirring continuously to ensure uniform distribution; Under an inert atmosphere, heat the dispersed system to 80-110°C and reflux for 4-6 hours; After the reaction is completed, the mixture is naturally cooled to room temperature and the modified nano-silica is separated by centrifugation; The separated modified nano-silica is washed with anhydrous hexane and then washed with anhydrous ethanol. The modified nano-silica is then dried in a vacuum oven at 80-100° C. for 2-4 hours to obtain the product.

6. The preparation method according to claim 5, characterized in that: The addition amount of the long-chain fluorosilane is 2% to 5% of the mass of the nano-silicon dioxide; The long-chain fluorosilane is 1H,1H,2H,2H-perfluorooctyltriethoxysilane.

7. The preparation method according to claim 4, characterized in that The silicone rubber matrix is PDMS grafted with hydroxyl side chains or PDMS grafted with amine side chains.

8. The preparation method according to claim 7, characterized in that The preparation process of the PDMS grafted with hydroxyl side chains specifically includes the following steps: Dissolve the Si-H functionalized PDMS in an anhydrous solvent, maintain the temperature and stir evenly to obtain a mixed solution A; Adding protected allyl alcohol and platinum catalyst to mixed solution A and stirring evenly, wherein the added amount of protected allyl alcohol is 5% to 10% of the mass of PDMS, and the added amount of platinum catalyst is 0.01% to 0.05% of the mass of PDMS; Under an inert atmosphere, the mixed solution A is heated to 60-70° C., reacted for 4-6 hours, and then deprotected using an acid or base. Subsequently, unreacted small molecules and catalyst residues are removed by precipitation or extraction, and then dried in a vacuum oven at 80-100° C. for 2-4 hours.

9. The preparation method according to claim 7, characterized in that The preparation process of the PDMS grafted with amino side chains specifically includes the following steps: Dissolve the Si-H functionalized PDMS in an anhydrous solvent, maintain the temperature and stir evenly to obtain a mixed solution B; Adding protected allylamine and platinum catalyst to mixed solution B and stirring evenly, wherein the amount of protected allylamine added is 5% to 10% of the mass of PDMS, and the amount of platinum catalyst added is 0.01% to 0.05% of the mass of PDMS; Under an inert atmosphere, the mixed solution B is heated to 60-70° C., reacted for 4-6 hours, and then deprotected using trifluoroacetic acid. Subsequently, unreacted small molecules and catalyst residues are removed by precipitation or extraction, and then dried in a vacuum oven at 80-100° C. for 2-4 hours.

10. The preparation method according to claim 4, characterized in that The hydrophobic silica is silica grafted on the surface of a PDMS-based silane coupling agent. The preparation process of the silica grafted on the surface of a PDMS-based silane coupling agent specifically includes the following steps: Place the silica in a vacuum oven and dry it at 110-120°C for 2-3 hours to remove surface moisture; Dispersing the dried silica in anhydrous toluene at a concentration of 5 to 10 wt%, and stirring with ultrasound and mechanical stirring for 30 to 60 minutes to obtain a second dispersion; Slowly add the PDMS silane coupling agent dropwise to the second dispersion, stirring continuously while adding to ensure uniform distribution; Under an inert atmosphere, heat the dispersed system to 80-110°C and reflux for 4-6 hours; After the reaction is completed, the mixture is naturally cooled to room temperature and the surface-grafted silica is separated by centrifugation; The separated surface-grafted silica is washed 2 to 3 times with anhydrous toluene, and then dried in a vacuum oven at 80 to 100° C. for 2 to 4 hours.

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