Protective film for electronic product and preparation method of protective film

Abstract

The invention relates to the technical field of adhesive protective films, in particular to a protective film for an electronic product and a preparation method of the protective film. The protective film for the electronic product comprises a base material layer and an adhesive layer covering the surface of the base material layer, the adhesive layer is formed by coating an EPDM-based adhesive on the surface of the base material layer and curing; the EPDM-based adhesive is prepared from the following raw materials in parts by mass: 50 to 150 parts of ethylene propylene diene monomer, 5 to 15 parts of epoxidized ethylene propylene diene monomer, 10 to 25 parts of heat-conducting filler, 2 to 4 parts of vulcanization system, 1 to 3 parts of stearic acid, 1 to 3 parts of anti-aging agent, 5 to 15 parts of hydrogenated rosin and 100 to 180 parts of solvent. According to the protective film, the high temperature resistance, the bonding reliability and the heat conduction efficiency are synergistically improved, the preparation method is simple, a reliable surface protection solution is provided for high-performance electronic products, the service life of the high-performance electronic products is effectively prolonged, and the protective film can be effectively applied to various electronic products.

Description

Technical Field

[0001] This invention relates to the field of adhesive protective film technology, and more particularly to a protective film for electronic products and its preparation method. Background Technology

[0002] As electronic products become increasingly prevalent in daily life, the need for surface protection during production, transportation, and use is also becoming more prominent. As a key protective material, the performance of protective films directly affects the appearance integrity and lifespan of electronic products. Currently, most self-adhesive protective films on the market are based on traditional polymer materials, which have significant limitations in temperature resistance, with melting points generally below 100℃.

[0003] However, under high-temperature environments, current protective films are prone to softening and degradation, and residues are easily left upon peeling, which not only contaminate the protected surface but also affect the aesthetics and functional reliability of electronic products. Especially for electronic and electrical products, the processing temperature typically requires temperatures above 150℃, which existing protective films struggle to meet. Furthermore, under extreme temperatures above 180℃, the adhesive layer is prone to failure or even delamination, failing to provide effective protection for high-power electronic components.

[0004] Ethylene propylene diene monomer (EPDM) rubber is considered a potential high-temperature adhesive substrate due to its stable molecular structure. However, because its main chain molecular structure is saturated and its side chains have few unsaturated double bonds, EPDM itself has poor adhesive properties and insufficient bonding strength, which restricts the overall bonding effect of the protective film. Moreover, under high temperature or mechanical stress, the protective film is prone to problems such as edge lifting and peeling, affecting the continuous protection of electronic products.

[0005] Modern electronic devices generate a significant amount of heat during operation. If the protective film has poor thermal conductivity, heat may accumulate, affecting device performance and lifespan. Boron nitride nanosheets, as two-dimensional nanomaterials, possess excellent in-plane thermal conductivity, theoretically capable of significantly improving the thermal conductivity of materials. However, boron nitride nanosheets in EPDM substrates suffer from poor interfacial compatibility and easy aggregation, making it difficult to construct an efficient and stable thermally conductive network and thus failing to meet the heat dissipation requirements of high-power-density electronic devices.

[0006] Therefore, developing a protective film that combines excellent high-temperature resistance, high adhesion strength, and good thermal conductivity to meet the protection needs of electronic products under complex operating conditions has become an urgent need in the field of electronic product surface protection. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a protective film for electronic products and its preparation method.

[0008] A protective film for electronic products includes: a substrate layer and an adhesive layer covering the surface of the substrate layer; the adhesive layer is formed by coating the substrate layer surface with an EPDM-based adhesive and then curing it; the raw materials of the EPDM-based adhesive include, by weight, 50-150 parts of EPDM rubber, 5-15 parts of epoxidized EPDM rubber, 10-25 parts of thermally conductive filler, 2-4 parts of vulcanization system, 1-3 parts of stearic acid, 1-3 parts of antioxidant, 5-15 parts of hydrogenated rosin, and 100-180 parts of solvent.

[0009] For information on epoxidized EPDM rubber, please refer to reference [1].

[0010] [1] Bian Jun, He Feixiong, Lin Hailan, et al. Study on the influence of epoxidized EPDM on the microstructure and mechanical properties of PBT / LLDPE blend system [J]. Plastics Industry, 2014, 42(8):6. DOI:10.3969 / j.issn.1005-5770.2014.08.008. Preferably, the thickness of the substrate layer is 40-60 μm, and the thickness of the adhesive layer is 10-20 μm.

[0011] Preferably, the vulcanization system includes: vulcanizing agent DCP and vulcanizing agent TAIC; the mass ratio of vulcanizing agent DCP to vulcanizing agent TAIC is 1-2:1-2.

[0012] Preferably, the antioxidant is antioxidant 1076 or / and antioxidant 1010.

[0013] Preferably, the solvent is at least one of toluene, ethyl acetate, and acetone.

[0014] Preferably, the thermally conductive filler is prepared by the following steps: hydroxylated boron nitride nanosheets and sodium dodecyl sulfate are added to toluene and ultrasonically dispersed for 1-2 hours; γ-glycidyl etheroxypropyltrimethoxysilane is added; the mixture is refluxed and stirred at 110-115°C for 1-2 hours; filtered, washed, and vacuum dried; then added to N,N-dimethylformamide; terminal amino polyamide amine is added; the mixture is stirred at 80-90°C for 1-2 hours; vinyltrimethoxysilane is added; the mixture is stirred at 110-115°C for 1-2 hours; and then distilled under reduced pressure.

[0015] More preferably, the mass ratio of hydroxylated boron nitride nanosheets, sodium dodecyl sulfate, γ-glycidyl etheroxypropyltrimethoxysilane, amino-terminated polyamide amine, and vinyltrimethoxysilane is 5-15:1-2:1-3:1-3:1-2.

[0016] More preferably, the ultrasonic frequency is 60-80kHz.

[0017] More preferably, hydroxylated boron nitride nanosheets are prepared by the following steps: adding boron nitride nanosheets to a sodium hydroxide solution, refluxing and stirring at 70-90°C for 1-3 hours, filtering, washing, and vacuum drying.

[0018] The preparation method of the above-mentioned protective film for electronic products includes the following steps: vacuum degassing of EPDM-based adhesive and coating it onto the surface of the substrate layer, heat treatment at 120-130℃ for 10-30 minutes to form an adhesive layer; bonding a release film onto the surface of the adhesive layer and curing at 70-80℃ for 15-25 hours.

[0019] Compared with existing technologies, the present invention has the following advantages: The EPDM-based adhesive used in this invention introduces active epoxy groups through epoxidation modification, which are then compounded with the vulcanization system (vulcanizing agent DCP and co-vulcanizing agent TAIC) to form a stable three-dimensional network structure. This structure can not only effectively inhibit the thermal motion of molecular chain segments at high temperatures, allowing the protective film to maintain its structural integrity above 150°C and preventing the adhesive layer from softening or degrading; but also react with the vinyl functional groups grafted onto the surface of the thermally conductive filler to further enhance the thermal stability of the entire system.

[0020] This invention utilizes the ring-opening reaction of hydroxylated boron nitride nanosheets with epoxy groups generated from the hydrolysis of γ-glycidoxypropyltrimethoxysilane, thereby grafting epoxy groups onto the surface of boron nitride. This further combines with dendritic terminal amino polyamide amine and vinyltrimethoxysilane, significantly enhancing the dispersion performance of the boron nitride nanosheets and suppressing agglomeration tendency. Furthermore, the introduced vinyl functional groups facilitate subsequent cross-linking reactions, strengthening the chemical bonding between the filler and the matrix, forming a tighter chemical bond. This increases the contact points between fillers and forms a continuous thermally conductive network in the matrix through chemical bonding, preventing localized heat accumulation. Meanwhile, hydrogenated rosin, as a tackifier, enhances the wettability of the adhesive film on the protected surface, thereby improving initial tack and long-lasting adhesion.

[0021] The protective film of this invention achieves a synergistic improvement in high temperature resistance, adhesion reliability, and thermal conductivity. Moreover, the preparation method is simple, providing a reliable surface protection solution for high-performance electronic products, effectively extending their service life, and can be effectively applied to protective films for various electronic products. Attached Figure Description

[0022] Figure 1 This is a comparison chart of the thermal conductivity and maximum withstand temperature of the protective films obtained in Example 5 and Comparative Examples 1-2.

[0023] Figure 2 This is a comparison chart of the original peel strength and peel strength retention rate of the protective films obtained in Example 5 and Comparative Examples 1-2. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0026] The substrate layer used below is a polyimide film, purchased from Changzhou Mouhui New Material Technology Co., Ltd., with a thickness of 50 μm. The release film used below is a PET release film, purchased from Shanghai Mouri Electronics Co., Ltd., with a thickness of 25 μm. The EPDM rubber used below is from Sinopec Mitsui, grade 3092EM. The amino-terminated polyamide amine (PAMAM, G4.0) used below is purchased from Hangzhou Xinqiao Biotechnology Co., Ltd. The boron nitride nanosheets (200 nm) used below are purchased from Zhejiang Xinmei Nanotechnology Co., Ltd. Example 1

[0027] A protective film for electronic products includes: a substrate layer, an adhesive layer (15 μm thick) covering the surface of the substrate layer, and a release film adhered to the surface of the adhesive layer.

[0028] The adhesive layer is formed by coating the substrate surface with an EPDM-based adhesive and then curing it. The raw materials for the EPDM-based adhesive include: 50g of EPDM rubber, 5g of epoxidized EPDM rubber, 10g of thermally conductive filler, 2g of vulcanization system, 1g of stearic acid, 1g of antioxidant 1010, 5g of hydrogenated rosin, and 100g of ethyl acetate. The vulcanization system consists of vulcanizing agent DCP and co-vulcanizing agent TAIC in a mass ratio of 1:2.

[0029] The thermally conductive filler was prepared using the following steps: 5g of hydroxylated boron nitride nanosheets and 1g of sodium dodecyl sulfate were added to 40g of toluene and ultrasonically dispersed for 1h at a frequency of 60kHz. 1g of γ-glycidoxypropyltrimethoxysilane was added, and the mixture was refluxed and stirred at 110℃ for 1h. The mixture was then filtered, washed, and vacuum dried. The filler was then added to 40g of N,N-dimethylformamide, and 1g of terminal amino polyamide amine was added. The mixture was stirred at 80℃ for 1h, and 1g of vinyltrimethoxysilane was added. The mixture was then stirred at 110℃ for 1h and distilled under reduced pressure.

[0030] Hydroxylated boron nitride nanosheets were prepared by the following steps: 5g of boron nitride nanosheets were added to 40g of a 2mol / L sodium hydroxide solution, refluxed and stirred at 70℃ for 1h, filtered, washed, and vacuum dried.

[0031] The EPDM-based adhesive is prepared as follows: EPDM rubber, epoxidized EPDM rubber, and thermally conductive filler are added to a mixer and mixed for 5 minutes at a mixing temperature of 50°C. Stearic acid and antioxidant 1010 are added and the mixture is continued for 1 minute at a mixing temperature of 90°C. The mixture is discharged at 110°C, passed through a rubber mill twice, and sheeted out. The sheet is then allowed to stand at 40°C for 2 hours to obtain the compound. Hydrogenated rosin is added to ethyl acetate and stirred until homogeneous to obtain a mixed solvent. The compound is calendered into 0.5 mm thick sheets on a two-roll mill, broken, and added to the mixed solvent. The mixture is stirred at 80°C for 5 hours, cooled to room temperature, and then added to the vulcanization system and stirred until homogeneous.

[0032] The preparation method of the above-mentioned protective film for electronic products includes the following steps: vacuum degassing of EPDM-based adhesive and coating it onto the surface of a substrate layer, heat-treating it at 130°C for 10 minutes to form an adhesive layer; bonding a release film onto the surface of the adhesive layer and curing it at 80°C for 15 hours. Example 2

[0033] A protective film for electronic products includes: a substrate layer, an adhesive layer (15 μm thick) covering the surface of the substrate layer, and a release film adhered to the surface of the adhesive layer.

[0034] The adhesive layer is formed by coating the substrate surface with an EPDM-based adhesive and then curing it. The raw materials for the EPDM-based adhesive include: 150g of EPDM rubber, 15g of epoxidized EPDM rubber, 25g of thermally conductive filler, 4g of vulcanization system, 3g of stearic acid, 3g of antioxidant 1010, 15g of hydrogenated rosin, and 180g of ethyl acetate. The vulcanization system consists of vulcanizing agent DCP and co-vulcanizing agent TAIC in a mass ratio of 2:1.

[0035] The thermally conductive filler was prepared using the following steps: 15g of hydroxylated boron nitride nanosheets and 2g of sodium dodecyl sulfate were added to 80g of toluene and ultrasonically dispersed for 2h at a frequency of 80kHz. 3g of γ-glycidoxypropyltrimethoxysilane was added, and the mixture was refluxed and stirred at 115℃ for 2h. The mixture was then filtered, washed, and vacuum dried. The filler was then added to 60g of N,N-dimethylformamide, and 3g of amino-terminated polyamide amine was added. The mixture was stirred at 90℃ for 2h, and 2g of vinyltrimethoxysilane was added. The mixture was stirred at 115℃ for 2h, and then distilled under reduced pressure.

[0036] Hydroxylated boron nitride nanosheets were prepared by the following steps: 15g of boron nitride nanosheets were added to 60g of a 4mol / L sodium hydroxide solution, refluxed and stirred at 90℃ for 3h, filtered, washed, and vacuum dried.

[0037] The EPDM-based adhesive is prepared as follows: EPDM rubber, epoxidized EPDM rubber, and thermally conductive filler are added to a mixer and mixed for 10 minutes at a mixing temperature of 70°C. Stearic acid and antioxidant 1010 are added and the mixture is continued for 5 minutes at a mixing temperature of 105°C. The mixture is discharged at 115°C and passed through a rubber mill 5 times to obtain a sheet. The sheet is then allowed to stand at 50°C for 4 hours to obtain the compound. Hydrogenated rosin is added to ethyl acetate and stirred until homogeneous to obtain a mixed solvent. The compound is calendered into a 1.5 mm thick sheet on a two-roll mill, broken, and added to the mixed solvent. The sheet is stirred at 90°C for 15 hours, cooled to room temperature, and then added to the vulcanization system and stirred until homogeneous.

[0038] The preparation method of the above-mentioned protective film for electronic products includes the following steps: vacuum degassing of EPDM-based adhesive and coating it onto the surface of a substrate layer, heat-treating it at 120°C for 30 minutes to form an adhesive layer; bonding a release film onto the surface of the adhesive layer and curing it at 70°C for 25 hours. Example 3

[0039] A protective film for electronic products includes: a substrate layer, an adhesive layer (15 μm thick) covering the surface of the substrate layer, and a release film adhered to the surface of the adhesive layer.

[0040] The adhesive layer is formed by coating the substrate surface with an EPDM-based adhesive and then curing it. The raw materials for the EPDM-based adhesive include: 80g of EPDM rubber, 12g of epoxidized EPDM rubber, 15g of thermally conductive filler, 3.5g of vulcanizing system, 1.5g of stearic acid, 2.5g of antioxidant 1010, 8g of hydrogenated rosin, and 170g of acetone. The vulcanizing system consists of vulcanizing agent DCP and co-vulcanizing agent TAIC in a mass ratio of 1.2:1.7.

[0041] The thermally conductive filler was prepared using the following steps: 8g of hydroxylated boron nitride nanosheets and 1.8g of sodium dodecyl sulfate were added to 50g of toluene and ultrasonically dispersed for 100min at a frequency of 65kHz. 2.5g of γ-glycidoxypropyltrimethoxysilane was added, and the mixture was refluxed and stirred at 111℃ for 100min. The mixture was then filtered, washed, and vacuum dried. The filler was then added to 45g of N,N-dimethylformamide, and 2.5g of amino-terminated polyamide amine was added. The mixture was stirred at 82℃ for 100min. 1.2g of vinyltrimethoxysilane was added, and the mixture was stirred at 113℃ for 80min. The mixture was then distilled under reduced pressure.

[0042] Hydroxylated boron nitride nanosheets were prepared by the following steps: 12g of boron nitride nanosheets were added to 45g of a 3.5mol / L sodium hydroxide solution, refluxed and stirred at 75℃ for 2.5h, filtered, washed, and vacuum dried.

[0043] The EPDM-based adhesive is prepared as follows: EPDM rubber, epoxidized EPDM rubber, and thermally conductive filler are added to a mixer and mixed for 7 minutes at a mixing temperature of 65°C. Stearic acid and antioxidant 1010 are added and the mixture is continued for 2 minutes at a mixing temperature of 100°C. The mixture is discharged at 111°C and passed through a rubber mill 4 times to obtain sheets. The sheets are then allowed to stand at 42°C for 3.5 hours to obtain the compound. Hydrogenated rosin is added to acetone and stirred evenly to obtain a mixed solvent. The compound is calendered into 1.0 mm thick sheets on a two-roll mill, broken, and added to the mixed solvent. The sheets are stirred at 82°C for 12 hours, cooled to room temperature, and then added to the vulcanization system and stirred evenly.

[0044] The preparation method of the above-mentioned protective film for electronic products includes the following steps: vacuum degassing of EPDM-based adhesive and coating it onto the surface of a substrate layer, heat-treating it at 122°C for 25 minutes to form an adhesive layer; bonding a release film onto the surface of the adhesive layer and curing it at 72°C for 22 hours. Example 4

[0045] A protective film for electronic products includes: a substrate layer, an adhesive layer (15 μm thick) covering the surface of the substrate layer, and a release film adhered to the surface of the adhesive layer.

[0046] The adhesive layer is formed by coating the substrate surface with EPDM-based adhesive and then curing. The raw materials for the EPDM-based adhesive include: 120g of EPDM rubber, 8g of epoxidized EPDM rubber, 20g of thermally conductive filler, 2.5g of vulcanizing system, 2.5g of stearic acid, 1.5g of antioxidant 1010, 12g of hydrogenated rosin, and 130g of acetone. The vulcanizing system consists of vulcanizing agent DCP and co-vulcanizing agent TAIC in a mass ratio of 1.8:1.3.

[0047] The thermally conductive filler was prepared using the following steps: 12g of hydroxylated boron nitride nanosheets and 1.2g of sodium dodecyl sulfate were added to 70g of toluene and ultrasonically dispersed for 80min at a frequency of 75kHz. 1.5g of γ-glycidoxypropyltrimethoxysilane was added, and the mixture was refluxed and stirred at 113℃ for 80min. The mixture was then filtered, washed, and vacuum dried. The filler was then added to 55g of N,N-dimethylformamide, and 1.5g of amino-terminated polyamide amine was added. The mixture was stirred at 88℃ for 80min. 1.8g of vinyltrimethoxysilane was added, and the mixture was stirred at 111℃ for 100min. The mixture was then distilled under reduced pressure.

[0048] Hydroxylated boron nitride nanosheets were prepared by the following steps: 8g of boron nitride nanosheets were added to 55g of a 2.5mol / L sodium hydroxide solution, refluxed and stirred at 85℃ for 1.5h, filtered, washed, and vacuum dried.

[0049] The EPDM-based adhesive is prepared as follows: EPDM rubber, epoxidized EPDM rubber, and thermally conductive filler are added to a mixer and mixed for 9 minutes at a mixing temperature of 55°C. Stearic acid and antioxidant 1010 are added and the mixture is continued for 4 minutes at a mixing temperature of 95°C. The mixture is discharged at 113°C and passed through a rubber mill three times to obtain sheets. The sheets are then allowed to stand at 48°C for 2.5 hours to obtain the compound. Hydrogenated rosin is added to acetone and stirred evenly to obtain a mixed solvent. The compound is calendered into 1.0 mm thick sheets on a two-roll mill, broken, and added to the mixed solvent. The sheets are stirred at 88°C for 8 hours, cooled to room temperature, and then added to the vulcanization system and stirred evenly.

[0050] The preparation method of the above-mentioned protective film for electronic products includes the following steps: vacuum degassing of EPDM-based adhesive and coating it onto the surface of a substrate layer, heat-treating it at 128°C for 15 minutes to form an adhesive layer; bonding a release film onto the surface of the adhesive layer and curing it at 78°C for 18 hours. Example 5

[0051] A protective film for electronic products includes: a substrate layer, an adhesive layer (15 μm thick) covering the surface of the substrate layer, and a release film adhered to the surface of the adhesive layer.

[0052] The adhesive layer is formed by coating the substrate surface with EPDM-based adhesive and then curing. The raw materials for the EPDM-based adhesive include: 100g of EPDM rubber, 10g of epoxidized EPDM rubber, 17.5g of thermally conductive filler, 3g of vulcanizing system, 2g of stearic acid, 2g of antioxidant 1010, 10g of hydrogenated rosin, and 150g of acetone. The vulcanizing system consists of vulcanizing agent DCP and co-vulcanizing agent TAIC in a 1:1 mass ratio.

[0053] The thermally conductive filler was prepared using the following steps: 10g of hydroxylated boron nitride nanosheets and 1.5g of sodium dodecyl sulfate were added to 60g of toluene and ultrasonically dispersed for 90min at a frequency of 70kHz. 2g of γ-glycidoxypropyltrimethoxysilane was added, and the mixture was refluxed and stirred at 112℃ for 90min. The mixture was then filtered, washed, and vacuum dried. The filler was then added to 50g of N,N-dimethylformamide, and 2g of terminal amino polyamide amine was added. The mixture was stirred at 85℃ for 90min. 1.5g of vinyltrimethoxysilane was added, and the mixture was stirred at 112℃ for 90min. The mixture was then distilled under reduced pressure.

[0054] Hydroxylated boron nitride nanosheets were prepared by the following steps: 10g of boron nitride nanosheets were added to 50g of a 3mol / L sodium hydroxide solution, refluxed and stirred at 80℃ for 2h, filtered, washed, and vacuum dried.

[0055] The EPDM-based adhesive is prepared as follows: EPDM rubber, epoxidized EPDM rubber, and thermally conductive filler are added to a mixer and mixed for 8 minutes at a mixing temperature of 60°C. Stearic acid and antioxidant 1010 are added and the mixture is continued for 3 minutes at a mixing temperature of 98°C. The mixture is discharged at 112°C and passed through a rubber mill 4 times to obtain a sheet. The sheet is then allowed to stand at 45°C for 3 hours to obtain the compound. Hydrogenated rosin is added to acetone and stirred evenly to obtain a mixed solvent. The compound is calendered into a 1.0 mm thick sheet on a two-roll mill, broken, and added to the mixed solvent. The sheet is stirred at 85°C for 10 hours, cooled to room temperature, and then added to the vulcanization system and stirred evenly.

[0056] The preparation method of the above-mentioned protective film for electronic products includes the following steps: vacuum degassing of EPDM-based adhesive and coating it onto the surface of a substrate layer, heat-treating it at 125°C for 20 minutes to form an adhesive layer; bonding a release film onto the surface of the adhesive layer and curing it at 75°C for 20 hours.

[0057] Comparative Example 1 A protective film for electronic products includes: a substrate layer, an adhesive layer (15 μm thick) covering the surface of the substrate layer, and a release film adhered to the surface of the adhesive layer.

[0058] The adhesive layer is formed by coating the substrate surface with EPDM-based adhesive and then curing. The raw materials for the EPDM-based adhesive include: 100g of EPDM rubber, 10g of epoxidized EPDM rubber, 17.5g of thermally conductive filler, 3g of vulcanizing system, 2g of stearic acid, 2g of antioxidant 1010, 10g of hydrogenated rosin, and 150g of acetone. The vulcanizing system consists of vulcanizing agent DCP and co-vulcanizing agent TAIC in a 1:1 mass ratio.

[0059] The thermally conductive filler was prepared using the following steps: 10g of hydroxylated boron nitride nanosheets and 1.5g of sodium dodecyl sulfate were added to 60g of toluene and ultrasonically dispersed for 90min at a frequency of 70kHz. 2g of γ-glycidoxypropyltrimethoxysilane was added, and the mixture was refluxed and stirred at 112℃ for 90min. The mixture was then filtered, washed, and vacuum dried. The filler was then added to 50g of N,N-dimethylformamide, and 1.5g of vinyltrimethoxysilane was added. The mixture was stirred at 112℃ for 90min and then distilled under reduced pressure.

[0060] Hydroxylated boron nitride nanosheets were prepared by the following steps: 10g of boron nitride nanosheets were added to 50g of a 3mol / L sodium hydroxide solution, refluxed and stirred at 80℃ for 2h, filtered, washed, and vacuum dried.

[0061] The EPDM-based adhesive is prepared as follows: EPDM rubber, epoxidized EPDM rubber, and thermally conductive filler are added to a mixer and mixed for 8 minutes at a mixing temperature of 60°C. Stearic acid and antioxidant 1010 are added and the mixture is continued for 3 minutes at a mixing temperature of 98°C. The mixture is discharged at 112°C and passed through a rubber mill 4 times to obtain a sheet. The sheet is then allowed to stand at 45°C for 3 hours to obtain the compound. Hydrogenated rosin is added to acetone and stirred evenly to obtain a mixed solvent. The compound is calendered into a 1.0 mm thick sheet on a two-roll mill, broken, and added to the mixed solvent. The sheet is stirred at 85°C for 10 hours, cooled to room temperature, and then added to the vulcanization system and stirred evenly.

[0062] The preparation method of the above-mentioned protective film for electronic products includes the following steps: vacuum degassing of EPDM-based adhesive and coating it onto the surface of a substrate layer, heat-treating it at 125°C for 20 minutes to form an adhesive layer; bonding a release film onto the surface of the adhesive layer and curing it at 75°C for 20 hours.

[0063] Comparative Example 2 A protective film for electronic products includes: a substrate layer, an adhesive layer (15 μm thick) covering the surface of the substrate layer, and a release film adhered to the surface of the adhesive layer.

[0064] The adhesive layer is formed by coating the substrate surface with EPDM-based adhesive and then curing. The raw materials for the EPDM-based adhesive include: 100g of EPDM rubber, 10g of epoxidized EPDM rubber, 17.5g of thermally conductive filler, 3g of vulcanizing system, 2g of stearic acid, 2g of antioxidant 1010, 10g of hydrogenated rosin, and 150g of acetone. The vulcanizing system consists of vulcanizing agent DCP and co-vulcanizing agent TAIC in a 1:1 mass ratio.

[0065] The thermally conductive filler was prepared using the following steps: 10g of hydroxylated boron nitride nanosheets and 1.5g of sodium dodecyl sulfate were added to 60g of toluene and ultrasonically dispersed for 90min at a frequency of 70kHz. 2g of γ-glycidyl etheroxypropyltrimethoxysilane was added, and the mixture was refluxed and stirred at 112℃ for 90min. The mixture was then filtered, washed, and vacuum dried. The filler was then added to 50g of N,N-dimethylformamide, and 2g of amino-terminated polyamide amine was added. The mixture was stirred at 85℃ for 90min and then distilled under reduced pressure.

[0066] Hydroxylated boron nitride nanosheets were prepared by the following steps: 10g of boron nitride nanosheets were added to 50g of a 3mol / L sodium hydroxide solution, refluxed and stirred at 80℃ for 2h, filtered, washed, and vacuum dried.

[0067] The EPDM-based adhesive is prepared as follows: EPDM rubber, epoxidized EPDM rubber, and thermally conductive filler are added to a mixer and mixed for 8 minutes at a mixing temperature of 60°C. Stearic acid and antioxidant 1010 are added and the mixture is continued for 3 minutes at a mixing temperature of 98°C. The mixture is discharged at 112°C and passed through a rubber mill 4 times to obtain a sheet. The sheet is then allowed to stand at 45°C for 3 hours to obtain the compound. Hydrogenated rosin is added to acetone and stirred evenly to obtain a mixed solvent. The compound is calendered into a 1.0 mm thick sheet on a two-roll mill, broken, and added to the mixed solvent. The sheet is stirred at 85°C for 10 hours, cooled to room temperature, and then added to the vulcanization system and stirred evenly.

[0068] The preparation method of the above-mentioned protective film for electronic products includes the following steps: vacuum degassing of EPDM-based adhesive and coating it onto the surface of a substrate layer, heat-treating it at 125°C for 20 minutes to form an adhesive layer; bonding a release film onto the surface of the adhesive layer and curing it at 75°C for 20 hours.

[0069] The thermal conductivity of the protective films obtained in Example 5 and Comparative Examples 1-2 was determined according to ASTM D5470. The maximum withstand temperature of the protective films obtained in Example 5 and Comparative Examples 1-2 was further determined as follows: the protective film was cut into 25mm × 200mm strips, applied to the surface of a steel plate, and placed in ovens at different temperatures for 30 minutes. After removal and cooling to room temperature, the tape was evenly peeled off, and the surface of the steel plate was observed for any adhesive residue. The highest temperature at which no adhesive residue appeared was set as the maximum withstand temperature.

[0070] like Figure 1 As shown, the protective film obtained in Example 5 has the highest thermal conductivity and maximum temperature tolerance, which is significantly better than that of Comparative Examples 1-2.

[0071] The peel strength (original) of the protective films obtained in Example 5 and Comparative Examples 1-2 was determined according to GB / T 2792-2014 "Test Method for Peel Strength of Adhesive Tapes". The protective films obtained in Example 5 and Comparative Examples 1-2 were placed in an oven at 160°C for 45 min, then the oven temperature was raised to 185°C and maintained for 20 min, then lowered to 160°C and maintained for 55 min. After removal, the peel strength was measured again, and the peel strength retention rate was calculated.

[0072] Peel strength retention rate = Peel strength after simulated working conditions ÷ Original peel strength × 100%.

[0073] like Figure 2 As shown, the protective film obtained in Example 5 has the highest original peel strength and peel strength retention rate, which is significantly better than that of Comparative Examples 1-2.

[0074] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. A protective film for electronic products, characterized in that, include: Substrate layer, adhesive layer covering the surface of the substrate layer; The adhesive layer is formed by coating the substrate layer with EPDM-based adhesive and then curing it. The raw materials of EPDM-based adhesives, by weight, include: 50-150 parts of EPDM rubber, 5-15 parts of epoxidized EPDM rubber, 10-25 parts of thermally conductive filler, 2-4 parts of vulcanization system, 1-3 parts of stearic acid, 1-3 parts of antioxidant, 5-15 parts of hydrogenated rosin, and 100-180 parts of solvent.

2. The protective film for electronic products according to claim 1, characterized in that, The thickness of the substrate layer is 40-60μm, and the thickness of the adhesive layer is 10-20μm.

3. The protective film for electronic products according to claim 1, characterized in that, The vulcanization system includes: vulcanizing agent DCP and vulcanizing agent TAIC; the mass ratio of vulcanizing agent DCP to vulcanizing agent TAIC is 1-2:1-2.

4. The protective film for electronic products according to claim 1, characterized in that, The antioxidant is antioxidant 1076 or / and antioxidant 1010.

5. The protective film for electronic products according to claim 1, characterized in that, The solvent is at least one of toluene, ethyl acetate, and acetone.

6. The protective film for electronic products according to claim 1, characterized in that, The thermally conductive filler was prepared using the following steps: hydroxylated boron nitride nanosheets and sodium dodecyl sulfate were added to toluene and ultrasonically dispersed for 1-2 hours. γ-glycidyl etheroxypropyltrimethoxysilane was then added, and the mixture was refluxed and stirred at 110-115°C for 1-2 hours. The mixture was then filtered, washed, and vacuum dried. The filler was then added to N,N-dimethylformamide, followed by the addition of amino-terminated polyamide amine. The mixture was stirred at 80-90°C for 1-2 hours, and then vinyltrimethoxysilane was added. The mixture was stirred at 110-115°C for 1-2 hours, and then distilled under reduced pressure.

7. The protective film for electronic products according to claim 6, characterized in that, The mass ratio of hydroxylated boron nitride nanosheets, sodium dodecyl sulfate, γ-glycidyl etheroxypropyltrimethoxysilane, amino-terminated polyamide amine, and vinyltrimethoxysilane is 5-15:1-2:1-3:1-3:1-2.

8. The protective film for electronic products according to claim 6, characterized in that, The ultrasonic frequency is 60-80kHz.

9. The protective film for electronic products according to claim 6, characterized in that, Hydroxylated boron nitride nanosheets were prepared by the following steps: adding boron nitride nanosheets to a sodium hydroxide solution, refluxing and stirring at 70-90℃ for 1-3 hours, filtering, washing, and vacuum drying.

10. A method for preparing a protective film for electronic products as described in any one of claims 1-9, characterized in that, The process includes the following steps: vacuum degassing the EPDM-based adhesive and then coating it onto the surface of the substrate layer; heat-treating at 120-130℃ for 10-30 minutes to form an adhesive layer; and curing at 70-80℃ for 15-25 hours.

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