Touch film and preparation method thereof

Abstract

The invention provides a touch film, and belongs to the technical field of touch films, the touch film is characterized in that a substrate is a silane modified PET film, both sides of the PET film are coupled with graphene oxide, the graphene oxide layer is coated with a polyurethane adhesive layer, and the polyurethane adhesive layer is attached to release paper. The thickness of the graphene oxide layer is 50-100 [mu] m, and the thickness of the polyurethane adhesive layer is 300-500 [mu] m. The preparation method of the touch film is simple, the raw material source is wide, the application range is wide, the problem that a rigid base material is damaged when being impacted by external force can be effectively solved, meanwhile, the heat resistance and the water resistance are improved, and the touch film is more suitable for protection of electronic devices.

Description

Technical Field

[0001] This invention relates to the field of tactile film technology, and more specifically to a tactile film. Background Technology

[0002] In the manufacturing process of electronic products such as mobile phones and computers, touchscreens need to be glued to the casing using adhesives. In recent years, with the development of high-performance and high-quality versions of electronic devices, electronic devices with very thin bezels are preferred. Therefore, it is necessary to prepare double-sided tapes with narrow widths to bond tempered glass to the touch panel. To meet this technical requirement, this is achieved by including a rigid film-type matrix material in the laminated structure of the double-sided tape. However, this type of double-sided tape containing a rigid film-type deteriorates during use due to the rigidity of the film-type matrix material. Especially when the touchscreen is subjected to external impact, the double-sided tape, due to its excessive rigidity, cannot buffer the impact, leading to adhesive failure and the touchscreen and tempered glass detaching.

[0003] Therefore, there is a need to develop a tactile film that combines rigidity and cushioning properties for use in modern electronic product touchscreens. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a tactile film and its preparation method. The purpose is to provide a tactile film that utilizes graphene oxide to modify the surface of a PET film substrate to obtain a rigid substrate with superior mechanical properties, enhanced wear resistance, and good weather resistance. The thick polyurethane adhesive layer provides bidirectional cushioning; the outer polyurethane adhesive layer buffers external impact forces, while the inner polyurethane adhesive layer buffers reaction forces, thus effectively protecting the rigid substrate material. Furthermore, the flame retardant and polytetrafluoroethylene powder added to the polyurethane adhesive layer give it excellent heat and water resistance. When used in touchscreens, this prevents damage to the screen due to poor heat dissipation or accidental water leakage, thus broadening its application range.

[0005] The present invention provides a tactile film, wherein the substrate is a silane-modified PET film, both sides of the PET film are coupled with graphene oxide, the graphene oxide layer is coated with a polyurethane adhesive layer, and the polyurethane adhesive layer is bonded to release paper.

[0006] As a further improvement of the present invention, the thickness of the graphene oxide layer is 50-100 μm, and the thickness of the polyurethane adhesive layer is 300-500 μm.

[0007] As a further improvement of the present invention, the polyurethane adhesive is prepared from the following raw materials in parts by weight: 100-120 parts of polyurethane adhesive, 15-23 parts of flame retardant, 3-7 parts of silane coupling agent, 25-30 parts of polytetrafluoroethylene powder, and 200-300 parts of acetone.

[0008] As a further improvement of the present invention, the polyurethane adhesive is prepared from the following raw materials in parts by weight: 110 parts polyurethane adhesive, 18 parts flame retardant, 6 parts silane coupling agent, 27 parts polytetrafluoroethylene powder and 250 parts acetone.

[0009] As a further improvement of the present invention, the polyurethane adhesive is prepared by the following method: dissolving a silane coupling agent in acetone, adding the polyurethane adhesive to the above solution, irradiating with ultraviolet light for 30-60 minutes, adding polytetrafluoroethylene powder and flame retardant to the solution, heating to 50-60°C, continuing the reaction for 2-3 hours, removing the solvent under reduced pressure, and obtaining the polyurethane adhesive.

[0010] As a further improvement of the present invention, the silane coupling agent is a silane coupling agent containing double bonds.

[0011] As a further improvement of the present invention, the silane coupling agent is 3-(methacryloyloxy)propyltrimethoxysilane and vinyltrimethoxysilane in a mass ratio of 2-5:1.

[0012] As a further improvement of the present invention, the flame retardant is selected from one of the flame retardants TCEP, BDP, TCPP, TPP, and RDP.

[0013] This invention further protects a method for preparing the above-mentioned tactile film, which is prepared according to the following method: S1. Graphene oxide was prepared using a modified Hummers method; S2. The PET film is placed in an acetone solution of silane coupling agent and soaked for 20-30 minutes. Then, the PET film is placed in the air and irradiated with ultraviolet light for 30-60 minutes to obtain a modified PET film. S3. Place the modified PET film prepared in step S2 into the ethanol dispersion of graphene oxide prepared in step S1, add ethylene-vinyl acetate copolymer EVA, stir and mix evenly, soak for 1-2 hours, take it out, wash and dry it to obtain a PET film coupled with graphene oxide on both sides. S4. One side of the graphene oxide-coupled PET film prepared in step S3 is uniformly coated with polyurethane adhesive using a coating machine, dried in an oven, and then glue is applied to the release paper. Subsequently, the release paper is laminated with one side of the PET film, and the other side is subjected to the same operation. The film is then wound up and cut to obtain a tactile film.

[0014] As a further improvement of the present invention, the oven temperature in step S4 is not higher than 50°C.

[0015] The present invention has the following beneficial effects: 1. This invention uses graphene oxide to modify the surface of a PET film substrate to obtain a rigid substrate, which has superior mechanical properties, is more wear-resistant, and has good weather resistance; 2. The polyurethane adhesive layer of this invention is relatively thick, which has a two-way buffering effect. The outer polyurethane adhesive layer can buffer external impact force, and the inner polyurethane adhesive layer can buffer reaction force, thereby achieving effective protection of the rigid material of the substrate. At the same time, the flame retardant and polytetrafluoroethylene powder added to the polyurethane adhesive layer can give the adhesive layer good heat resistance and water resistance. When used in touch screens, it can avoid damage to the screen due to poor heat dissipation of the machine and damage to the screen when the machine is accidentally exposed to water. It has a wide range of applications. 3. The preparation method of this invention is simple, the raw materials are widely available, and the application is wide. It can effectively solve the problem of damage to rigid substrates when subjected to external impact. At the same time, it has improved heat resistance and water resistance, making it more suitable for the protection of electronic devices. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation process of the tactile film of the present invention. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the embodiments described are only some representative embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0018] Example 1

[0019] In Example 1, the tactile film substrate was a silane-modified PET film. Both sides of the PET film were coupled with graphene oxide. A polyurethane adhesive layer was coated on the outside of the graphene oxide layer, and a release paper was laminated to the outside of the polyurethane adhesive layer. The thickness of the graphene oxide layer was 50 μm, and the thickness of the polyurethane adhesive layer was 300 μm.

[0020] Preparation of polyester adhesive: Raw material composition (parts by weight): 100 parts polyurethane adhesive, 15 parts flame retardant, 3 parts silane coupling agent, 25 parts polytetrafluoroethylene powder, and 200 parts acetone.

[0021] The silane coupling agent is 3-(methacryloyloxy)propyltrimethoxysilane and vinyltrimethoxysilane in a mass ratio of 2:1.

[0022] The polyurethane adhesive was prepared by the following method: a silane coupling agent was dissolved in acetone, polyurethane adhesive was added to the solution, and after irradiation with ultraviolet light for 30 min, polytetrafluoroethylene powder and flame retardant were added to the solution. The temperature was raised to 50°C and the reaction was continued for 2 h. The solvent was removed under reduced pressure to obtain the polyurethane adhesive.

[0023] Example 1: Preparation method of tactile film, prepared according to the following method: S1. Graphene oxide was prepared using a modified Hummers method; Step 1: Weigh 10 g of natural graphite powder (G), 4 g of potassium persulfate, and 10 g of phosphorus pentoxide. Add them to a three-necked flask containing 24 mL of sulfuric acid while stirring. First, react in a 60°C constant temperature water bath for 3 h. Then, transfer the three-necked flask to a 25°C constant temperature water bath for 5 h. Filter the mixture and wash it with deionized water until neutral. Dry it in air to obtain pre-oxidized graphite (PG). Step 2: Weigh 1g of pre-oxidized graphite and add it to a three-necked flask containing 25 mL of sulfuric acid while stirring. Place the flask in an ice-water bath and wait until the pre-oxidized graphite is completely dissolved. Then add 3g of potassium permanganate and react for 2 hours. Transfer the flask to a constant temperature water bath at 35°C and react for 40 minutes. Finally, add deionized water and continue reacting at 35°C for 1 hour. Finally, add 30% H2O2 dropwise until no more gas is generated and the solution turns bright yellow. Centrifuge and filter while hot, and wash with plenty of 5% hydrochloric acid and deionized water until neutral. After sonicating the final precipitate for 1 hour, pour it into a petri dish and dry at 90°C for 24 hours to obtain sheet-like graphite oxide (GO). S2. The PET film is placed in an acetone solution of silane coupling agent and soaked for 20 minutes. Then, the PET film is placed in the air and irradiated with ultraviolet light for 30 minutes to obtain a modified PET film. S3. Place the modified PET film prepared in step S2 into the ethanol dispersion of graphene oxide prepared in step S1, add ethylene-vinyl acetate copolymer EVA, with a final mass percentage of 5wt%, stir and mix evenly, soak for 1-2 hours, take it out, wash and dry it to obtain a PET film coupled with graphene oxide on both sides. S4. One side of the graphene oxide-coupled PET film prepared in step S3 is uniformly coated with polyurethane adhesive using a coating machine, placed in an oven to dry, and the oven temperature is not higher than 50°C. Adhesive is applied to the release paper, and then the release paper is laminated with one side of the PET film. The other side is subjected to the same operation, then wound up and cut to obtain the tactile film.

[0024] Example 2

[0025] In Example 2, the tactile film substrate was a silane-modified PET film. Both sides of the PET film were coupled with graphene oxide. A polyurethane adhesive layer was coated on the outside of the graphene oxide layer, and a release paper was laminated to the outside of the polyurethane adhesive layer. The thickness of the graphene oxide layer was 100 μm, and the thickness of the polyurethane adhesive layer was 500 μm.

[0026] Preparation of polyester adhesive: Raw material composition (parts by weight): 120 parts polyurethane adhesive, 23 parts flame retardant, 7 parts silane coupling agent, 30 parts polytetrafluoroethylene powder, and 300 parts acetone.

[0027] The silane coupling agent is 3-(methacryloyloxy)propyltrimethoxysilane and vinyltrimethoxysilane in a mass ratio of 5:1.

[0028] The polyurethane adhesive was prepared by the following method: a silane coupling agent was dissolved in acetone, polyurethane adhesive was added to the solution, and after irradiation with ultraviolet light for 60 min, polytetrafluoroethylene powder and flame retardant were added to the solution. The temperature was raised to 60°C and the reaction was continued for 3 h. The solvent was removed under reduced pressure to obtain the polyurethane adhesive.

[0029] Example 2: Preparation method of the tactile film, which is prepared according to the following method: S1. Graphene oxide was prepared using a modified Hummers method; Step 1: Weigh 10 g of natural graphite powder (G), 4 g of potassium persulfate, and 10 g of phosphorus pentoxide. Add them to a three-necked flask containing 24 mL of sulfuric acid while stirring. First, react in a 60°C constant temperature water bath for 3 h. Then, transfer the three-necked flask to a 25°C constant temperature water bath for 5 h. Filter the mixture and wash it with deionized water until neutral. Dry it in air to obtain pre-oxidized graphite (PG). Step 2: Weigh 1g of pre-oxidized graphite and add it to a three-necked flask containing 25 mL of sulfuric acid while stirring. Place the flask in an ice-water bath and wait until the pre-oxidized graphite is completely dissolved. Then add 3g of potassium permanganate and react for 2 hours. Transfer the flask to a constant temperature water bath at 35°C and react for 40 minutes. Finally, add deionized water and continue reacting at 35°C for 1 hour. Finally, add 30% H2O2 dropwise until no more gas is generated and the solution turns bright yellow. Centrifuge and filter while hot, and wash with plenty of 5% hydrochloric acid and deionized water until neutral. After sonicating the final precipitate for 1 hour, pour it into a petri dish and dry at 90°C for 24 hours to obtain sheet-like graphite oxide (GO). S2. The PET film is placed in an acetone solution of silane coupling agent and soaked for 30 minutes. Then, the PET film is placed in the air and irradiated with ultraviolet light for 60 minutes to obtain a modified PET film. S3. Place the modified PET film prepared in step S2 into the ethanol dispersion of graphene oxide prepared in step S1, add ethylene-vinyl acetate copolymer EVA, with a final mass percentage of 5wt%, stir and mix evenly, soak for 2 hours, take it out, wash and dry it to obtain a PET film coupled with graphene oxide on both sides. S4. One side of the graphene oxide-coupled PET film prepared in step S3 is uniformly coated with polyurethane adhesive using a coating machine, placed in an oven to dry, and the oven temperature is not higher than 50°C. Adhesive is applied to the release paper, and then the release paper is laminated with one side of the PET film. The other side is subjected to the same operation, then wound up and cut to obtain the tactile film.

[0030] Example 3

[0031] In Example 3, the tactile film substrate was a silane-modified PET film. Both sides of the PET film were coupled with graphene oxide. A polyurethane adhesive layer was coated on the outside of the graphene oxide layer, and a release paper was laminated to the outside of the polyurethane adhesive layer. The thickness of the graphene oxide layer was 75 μm, and the thickness of the polyurethane adhesive layer was 400 μm.

[0032] Preparation of polyester adhesive: Raw material composition (parts by weight): 110 parts polyurethane adhesive, 18 parts flame retardant, 6 parts silane coupling agent, 27 parts polytetrafluoroethylene powder, and 250 parts acetone.

[0033] The silane coupling agent is 3-(methacryloyloxy)propyltrimethoxysilane and vinyltrimethoxysilane in a mass ratio of 3.5:1.

[0034] The polyurethane adhesive was prepared by the following method: a silane coupling agent was dissolved in acetone, polyurethane adhesive was added to the solution, and after irradiation with ultraviolet light for 45 min, polytetrafluoroethylene powder and flame retardant were added to the solution. The temperature was raised to 55°C and the reaction was continued for 2.5 h. The solvent was removed under reduced pressure to obtain the polyurethane adhesive.

[0035] Example 3: Preparation method of the tactile film, which is prepared according to the following method: S1. Graphene oxide was prepared using a modified Hummers method; Step 1: Weigh 10 g of natural graphite powder (G), 4 g of potassium persulfate, and 10 g of phosphorus pentoxide. Add them to a three-necked flask containing 24 mL of sulfuric acid while stirring. First, react in a 60°C constant temperature water bath for 3 h. Then, transfer the three-necked flask to a 25°C constant temperature water bath for 5 h. Filter the mixture and wash it with deionized water until neutral. Dry it in air to obtain pre-oxidized graphite (PG). Step 2: Weigh 1g of pre-oxidized graphite and add it to a three-necked flask containing 25 mL of sulfuric acid while stirring. Place the flask in an ice-water bath and wait until the pre-oxidized graphite is completely dissolved. Then add 3g of potassium permanganate and react for 2 hours. Transfer the flask to a constant temperature water bath at 35°C and react for 40 minutes. Finally, add deionized water and continue reacting at 35°C for 1 hour. Finally, add 30% H2O2 dropwise until no more gas is generated and the solution turns bright yellow. Centrifuge and filter while hot, and wash with plenty of 5% hydrochloric acid and deionized water until neutral. After sonicating the final precipitate for 1 hour, pour it into a petri dish and dry at 90°C for 24 hours to obtain sheet-like graphite oxide (GO). S2. The PET film is placed in an acetone solution of silane coupling agent and soaked for 25 minutes. Then, the PET film is placed in the air and irradiated with ultraviolet light for 45 minutes to obtain a modified PET film. S3. The modified PET film prepared in step S2 is placed in the ethanol dispersion of graphene oxide prepared in step S1, and ethylene-vinyl acetate copolymer EVA is added at a final mass percentage of 5 wt%. The mixture is stirred and mixed evenly, soaked for 1.5 h, removed, washed and dried to obtain a PET film coupled with graphene oxide on both sides. S4. One side of the graphene oxide-coupled PET film prepared in step S3 is uniformly coated with polyurethane adhesive using a coating machine, placed in an oven to dry, and the oven temperature is not higher than 50°C. Adhesive is applied to the release paper, and then the release paper is laminated with one side of the PET film. The other side is subjected to the same operation, then wound up and cut to obtain the tactile film.

[0036] Example 4

[0037] The difference from Example 3 is that the silane coupling agent is a single 3-(methacryloyloxy)propyltrimethoxysilane.

[0038] Example 5

[0039] The difference from Example 3 is that the silane coupling agent is a single vinyltrimethoxysilane.

[0040] Example 6

[0041] The difference from Example 3 is that the silane coupling agent is a single 3-(methacryloyloxy)propyltrimethoxysilane and vinyltrimethoxysilane in a mass ratio of 10:1.

[0042] Example 7

[0043] The difference from Example 3 is that the silane coupling agent is a single 3-(methacryloyloxy)propyltrimethoxysilane and vinyltrimethoxysilane in a mass ratio of 1:10.

[0044] Comparative Example 1 Prepared according to the method of Chinese invention patent application (publication number CN 108504296 A) S1. Mix the adhesive with thermoplastic polyurethane foam particles and polyurethane particles according to the volume ratio to form the first adhesive layer adhesive and the second adhesive layer adhesive. S2. Install the carbon fiber cloth onto the substrate layer unwinding roller, add the first adhesive layer adhesive and the second adhesive layer adhesive to the corresponding doctor blade coating machine, and install the first release film 1 and the second release film onto the release film unwinding roller. S3. Start all equipment. The doctor blade coater coats the first adhesive layer and the second adhesive layer on both sides of the carbon fiber cloth. Then, the carbon fiber cloth is sent into the drying device to remove the solvent in the adhesive, forming the first adhesive layer and the second adhesive layer. The first adhesive layer and the second adhesive layer are then bonded to the first release film 1 and the second release film, respectively. S4. Send the product obtained in S3 to the winding device for winding to obtain the finished product.

[0045] Test Example 1 Performance Test The tactile films prepared in Examples 1-3 and Comparative Example 1 of this invention were subjected to performance tests, and the results are shown in Table 1.

[0046] Table 1 Performance Test Results

[0047] As can be seen from the table above, the tactile films prepared in Examples 1-3 of the present invention have better overall performance compared with Comparative Example 1: they have high adhesive performance, better resistance to warping, good holding power, extremely low thermal resistance, and excellent weather resistance and water resistance.

[0048] Compared with existing technologies, this invention uses graphene oxide to modify the surface of the PET film substrate to obtain a rigid substrate, which has superior mechanical properties, better wear resistance, and better weather resistance. The polyurethane adhesive layer of this invention is thicker and has a bidirectional buffering effect. The outer polyurethane adhesive layer can buffer external impact force, and the inner polyurethane adhesive layer can buffer reaction force, thereby effectively protecting the rigid material of the substrate. At the same time, the flame retardant and polytetrafluoroethylene powder added to the polyurethane adhesive layer can give the adhesive layer good heat resistance and water resistance. When used in touch screens, it can prevent damage to the screen due to poor heat dissipation of the machine or damage to the screen when the machine is accidentally leaked. It has a wide range of applications. The preparation method of this invention is simple, the raw materials are widely available, and the application is wide-ranging. It can effectively solve the problem of rigid substrates being damaged by external impact, while also improving heat resistance and water resistance, making it more suitable for the protection of electronic devices.

[0049] Those skilled in the art can make various modifications to the above description without departing from the spirit and scope of the invention as defined in the claims. Therefore, the scope of the invention is not limited to the above description, but is determined by the scope of the claims.

Claims

1. A tactile film, characterized in that, The substrate is a silane-modified PET film, both sides of which are coupled with graphene oxide. The graphene oxide layer is coated with a polyurethane adhesive layer, and the polyurethane adhesive layer is bonded to release paper.

2. The tactile film according to claim 1, characterized in that, The thickness of the graphene oxide layer is 50-100 μm, and the thickness of the polyurethane adhesive layer is 300-500 μm.

3. The tactile film according to claim 1, characterized in that, The polyurethane adhesive is prepared from the following raw materials in parts by weight: 100-120 parts polyurethane adhesive, 15-23 parts flame retardant, 3-7 parts silane coupling agent, 25-30 parts polytetrafluoroethylene powder, and 200-300 parts acetone.

4. The tactile film according to claim 2, characterized in that, The polyurethane adhesive is prepared from the following raw materials in parts by weight: 110 parts polyurethane adhesive, 18 parts flame retardant, 6 parts silane coupling agent, 27 parts polytetrafluoroethylene powder, and 250 parts acetone.

5. The tactile membrane according to claim 3 or 4, characterized in that, The polyurethane adhesive is prepared by the following method: a silane coupling agent is dissolved in acetone, the polyurethane adhesive is added to the above solution, and after irradiation with ultraviolet light for 30-60 minutes, polytetrafluoroethylene powder and flame retardant are added to the solution, the temperature is raised to 50-60℃, the reaction is continued for 2-3 hours, the solvent is removed under reduced pressure, and the polyurethane adhesive is obtained.

6. The tactile film according to claim 3 or 4, characterized in that, The silane coupling agent is a silane coupling agent containing double bonds.

7. The tactile film according to claim 6, characterized in that, The silane coupling agent is 3-(methacryloyloxy)propyltrimethoxysilane and vinyltrimethoxysilane in a mass ratio of 2-5:

1.

8. The tactile membrane according to claim 3 or 4, characterized in that, The flame retardant is selected from one of the following: TCEP, BDP, TCPP, TPP, and RDP.

9. The method for preparing a tactile film according to claim 1, characterized in that, Prepared according to the following method: S1. Graphene oxide was prepared using a modified Hummers method; S2. The PET film is placed in an acetone solution of silane coupling agent and soaked for 20-30 minutes. Then, the PET film is placed in the air and irradiated with ultraviolet light for 30-60 minutes to obtain a modified PET film. S3. Place the modified PET film prepared in step S2 into the ethanol dispersion of graphene oxide prepared in step S1, add ethylene-vinyl acetate copolymer EVA, stir and mix evenly, soak for 1-2 hours, take it out, wash and dry it to obtain a PET film coupled with graphene oxide on both sides. S4. One side of the graphene oxide-coupled PET film prepared in step S3 is uniformly coated with polyurethane adhesive using a coating machine, dried in an oven, and then glue is applied to the release paper. Subsequently, the release paper is laminated with one side of the PET film, and the other side is subjected to the same operation. The film is then wound up and cut to obtain a tactile film.

10. The method for preparing the tactile film according to claim 9, characterized in that, In step S4, the oven temperature should not exceed 50°C.

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