Pressure-sensitive adhesive protective film for ITO (indium tin oxide) glass and preparation method of pressure-sensitive adhesive protective film

Abstract

The invention discloses a pressure-sensitive adhesive protective film for ITO (indium tin oxide) glass, which comprises a polyester film substrate and an organic silicon pressure-sensitive adhesive layer coated on the surface of the polyester film substrate, and the organic silicon pressure-sensitive adhesive layer is formed by coating and curing a mixture; the mixture is prepared from 90 to 150 parts of high vinyl silicone oil, 90 to 150 parts of MQ silicon resin, 10 to 14 parts of hydrogen-based polysiloxane cross-linking agent, 5 to 12 parts of nano SiO2 filler, 4 to 10 parts of nano Al2O3 filler, 0.2 to 0.8 part of anchoring agent and 2 to 3 parts of antistatic agent; the vinyl content of the high vinyl silicone oil is 0.5 mmol / g to 1.2 mmol / g. Through the mode, according to the pressure-sensitive adhesive protective film for the ITO glass and the preparation method of the pressure-sensitive adhesive protective film, through an innovative material formula system and refined process design, the manufactured protective film overcomes the defects generated when an existing pressure-sensitive adhesive protective film is used for the ITO glass, the excellent scratch resistance is ensured, and meanwhile the pressure-sensitive adhesive protective film can be applied to the ITO glass. Extremely low film tearing voltage, controllable and stable moderate viscosity and high light transmittance are realized.

Description

Technical Field

[0001] This invention belongs to the field of protective film technology, specifically relating to a pressure-sensitive adhesive protective film for ITO glass and its preparation method. Background Technology

[0002] In the manufacturing process of electronic products such as flat panel displays and touch panels, ITO conductive glass is one of the key substrates. To prevent it from being scratched, contaminated, and damaged by static electricity during transportation, storage, and processing, a temporary protective film is usually applied to the ITO surface. This protective film needs to have excellent anti-friction and anti-scratch properties to resist scratches from external hard objects. Secondly, it needs to have suitable and stable adhesion to ensure that it does not peel off or fall off during processing, while also being easily and cleanly peeled off without leaving any residue or damaging the ITO layer and underlying structures such as polarizers. Furthermore, to avoid affecting optical inspection and the final optical performance of the product, the protective film needs to have high light transmittance and low haze. In addition, to eliminate appearance defects or potential scratches caused by static electricity attracting dust, it also needs to have anti-static properties.

[0003] Currently, some protective films on the market often fail to achieve the above-mentioned performance. In pursuit of high hardness and scratch resistance, too many rigid fillers are added or the cross-linking density is increased, which often leads to the protective film becoming brittle, reducing its flexibility, and making it easy to break or retain internal stress when peeling. At the same time, it may cause an imbalance in adhesion, excessive peeling force, or the generation of adhesive residue.

[0004] Traditional silicone pressure-sensitive adhesives have high curing temperatures (usually exceeding 160°C). Prolonged high-temperature environments may adversely affect the conductivity of the ITO layer and the stability of the glass. In addition, ordinary protective films are prone to generating electrostatic voltages of hundreds or even thousands of volts when peeled off, posing a risk of attracting dust or causing electric shocks that could damage sensitive components. Summary of the Invention

[0005] The main technical problem solved by this invention is to provide a pressure-sensitive adhesive protective film for ITO glass and its preparation method, which can solve the defects of existing pressure-sensitive adhesive protective films when used for ITO glass.

[0006] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a pressure-sensitive adhesive protective film for ITO glass, comprising a polyester film substrate and an organosilicon pressure-sensitive adhesive layer coated on its surface, wherein the organosilicon pressure-sensitive adhesive layer is formed by coating and curing a mixture; The mixture comprises 90-150 parts of high vinyl silicone oil, 90-150 parts of MQ silicone resin, 10-14 parts of hydrogen-based polysiloxane crosslinking agent, 5-12 parts of nano-SiO2 filler, 4-10 parts of nano-Al2O3 filler, 0.2-0.8 parts of anchoring agent, and 2-3 parts of antistatic agent. The vinyl content of the high vinyl silicone oil is 0.5 mmol / g to 1.2 mmol / g.

[0007] In a preferred embodiment of the present invention, the thickness of the polyester film substrate is 25μm~100μm, and its elastic modulus is not less than 4.0Gpa.

[0008] In a preferred embodiment of the present invention, the average particle size of the nano-SiO2 filler is 10nm~50nm.

[0009] In a preferred embodiment of the present invention, the average particle size of the nano-Al2O3 filler is 20nm~80nm.

[0010] In a preferred embodiment of the present invention, 2% organosilicon surfactant is added to the antistatic agent.

[0011] In a preferred embodiment of the present invention, the pressure-sensitive adhesive protective film requires plasma treatment of the ITO glass surface before use.

[0012] In a preferred embodiment of the present invention, the surface energy of the ITO glass after plasma treatment is greater than 79 mJ / m.

[0013] A method for preparing a pressure-sensitive adhesive protective film for ITO glass, comprising the following steps: 1) Pretreatment: The nano-SiO2 filler and the nano-Al2O3 filler are surface-treated with vinyl silane coupling agent and then dried for later use; 2) Adhesive preparation: The high vinyl silicone oil, the MQ silicone resin, the treated nano SiO2 filler, the treated nano Al2O3 filler, the anchoring agent and the antistatic agent are dispersed evenly at high speed in a planetary mixer to form the main agent. Then the hydrogen-based polysiloxane crosslinking agent is added, and the mixture is stirred at medium and low speed until it is evenly mixed. After vacuum degassing, the adhesive solution is obtained. 3) Substrate treatment: On the corona-treated surface of the polyester film substrate, a thin layer of silane coupling agent is first coated by microgravure coating, and then dried at 80~120℃ for 20~40 seconds to form a base coating. 4) Coating and curing: The adhesive solution obtained in step 2) is coated onto the base layer formed in step 3), and the wet film thickness is controlled to be 50 μm. Then, the coated film is placed in a hot air circulating oven and cured at 140~150℃ for 90~110 seconds to form an organosilicon pressure-sensitive adhesive layer with a dry film thickness of 25 μm. The protective film is then rolled up to obtain the finished product.

[0014] The beneficial effects of this invention are as follows: This invention provides a pressure-sensitive adhesive protective film for ITO glass and its preparation method. Through an innovative material formulation system and refined process design, the protective film produced by this method solves the defects of existing pressure-sensitive adhesive protective films when used on ITO glass. While ensuring excellent scratch resistance, it achieves extremely low tear voltage, controllable and stable moderate adhesion and high light transmittance, and meets the special adhesion requirements of ITO glass surface. Moreover, the process temperature is mild, which is suitable for the needs of modern precision electronic manufacturing. Detailed Implementation

[0015] The preferred embodiments of the present invention will now be described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0016] A pressure-sensitive adhesive protective film for ITO glass includes a polyester film substrate and an organosilicon pressure-sensitive adhesive layer coated on its surface. The organosilicon pressure-sensitive adhesive layer is formed by coating and curing a mixture. Through an innovative material formulation system and refined process design, the manufactured protective film solves the defects of existing pressure-sensitive adhesive protective films used on ITO glass. While ensuring excellent scratch resistance, it achieves extremely low tear voltage, controllable and stable moderate adhesion, and high light transmittance, and meets the special adhesion requirements of ITO glass surface. Moreover, the process temperature is mild, which is suitable for the needs of modern precision electronic manufacturing.

[0017] The mixture comprises 90-150 parts of high vinyl silicone oil, 90-150 parts of MQ silicone resin, 10-14 parts of hydrogen-based polysiloxane crosslinking agent, 5-12 parts of nano-SiO2 filler, 4-10 parts of nano-Al2O3 filler, 0.2-0.8 parts of anchoring agent, and 2-3 parts of antistatic agent.

[0018] The high vinyl silicone oil and the MQ silicone resin are used to balance the low glass transition temperature and high modulus properties, ensuring flexibility while improving scratch resistance.

[0019] The synergistic effect of the nano-SiO2 filler and the nano-Al2O3 filler can significantly improve the friction and scratch resistance of the organosilicon pressure-sensitive adhesive layer. The uniform dispersion of the nano-filler can enhance the density of the adhesive layer and reduce surface defects.

[0020] The hydrogen-based polysiloxane crosslinking agent can optimize the crosslinking density and enhance the mechanical strength of the silicone pressure-sensitive adhesive layer.

[0021] The anchoring agent can improve the interfacial bonding force between the silicone pressure-sensitive adhesive layer and the ITO glass, and prevent residual adhesive or silicone transfer during peeling.

[0022] The vinyl content of the high vinyl silicone oil is 0.5 mmol / g to 1.2 mmol / g, which is used to control the number of active sites in the crosslinking reaction. This directly affects the crosslinking density, modulus, and flexibility of the final adhesive layer. If the content is too low, the crosslinking will be insufficient and the performance will be weak. If the content is too high, the adhesive layer may become brittle.

[0023] The thickness of the polyester film substrate is 25μm~100μm, and its elastic modulus is not less than 4.0Gpa, ensuring that the substrate has sufficient support and resistance to deformation. If it is too thin or too soft, it will reduce the stiffness and scratch resistance of the protective film. If it is too thick, it will be uneconomical and affect the flexibility. This is the basic guarantee for achieving the overall mechanical properties.

[0024] The average particle size of the nano-SiO2 filler is 10nm~50nm, and the average particle size of the nano-Al2O3 filler is 20nm~80nm, which makes the nano-SiO2 filler and the nano-Al2O3 filler small enough to be uniformly dispersed in the adhesive layer, avoiding the generation of light scattering and stress concentration points.

[0025] The antistatic agent contains 2% silicone surfactant, which can reduce the stripping voltage and prevent static electricity from attracting dust and scratching the surface.

[0026] The pressure-sensitive adhesive protective film requires plasma treatment of the ITO glass surface before use. After plasma treatment, the ITO glass surface exhibits a surface strength greater than 79 mJ / m, which enhances the adhesion of the silicone pressure-sensitive adhesive layer and reduces the coefficient of friction. Example 1 A method for preparing a pressure-sensitive adhesive protective film for ITO glass, comprising the following steps: 1) Pretreatment: The nano-SiO2 filler and the nano-Al2O3 filler are surface treated with vinyl silane coupling agent and then dried for later use.

[0027] The nano-SiO2 filler and the nano-Al2O3 filler are treated with a vinyl silane coupling agent to improve their compatibility with the organosilicon matrix, prevent agglomeration, and enhance cohesive strength.

[0028] 2) Adhesive formulation: 120 parts of the high vinyl silicone oil, 120 parts of the MQ silicone resin, 8 parts of the treated nano-SiO2 filler, 8 parts of the treated nano-Al2O3 filler, 0.5 parts of the anchoring agent and 2.5 parts of the antistatic agent are dispersed evenly at high speed in a planetary mixer to form the main agent. Then, 12 parts of the hydrogen-based polysiloxane crosslinking agent are added, and the mixture is stirred at medium and low speed until it is evenly mixed. After vacuum degassing, the adhesive solution is obtained.

[0029] 3) Substrate treatment: A transparent polyester film with a thickness of 50μm and an elastic modulus of 4.2GPa is selected as the substrate. A thin layer of silane coupling agent is first coated on its corona-treated surface by microgravure coating and dried at 120℃ for 20 seconds to form a base coating.

[0030] 4) Coating and curing: The adhesive solution obtained in step 2) is coated onto the base layer formed in step 3), and the wet film thickness is controlled to be 50 μm. Then, the coated film is placed in a hot air circulating oven and cured at 140°C for 110 seconds to form an organosilicon pressure-sensitive adhesive layer with a dry film thickness of 25 μm. The protective film is then rolled up to obtain the finished product.

[0031] Low-temperature curing can reduce the damage of high temperature to the ITO conductive layer, while ensuring that the silicone pressure-sensitive adhesive layer is fully cross-linked.

[0032] This application employs a multi-layer coating process, first applying the primer layer and then the silicone pressure-sensitive adhesive layer. The primer layer greatly enhances the adhesion between the silicone pressure-sensitive adhesive layer and the polyester film substrate, preventing interlayer peeling of the protective film during use or peeling. This is a key process detail for improving product reliability.

[0033] Example 2 A method for preparing a pressure-sensitive adhesive protective film for ITO glass, comprising the following steps: 1) Pretreatment: The nano-SiO2 filler and the nano-Al2O3 filler are surface treated with vinyl silane coupling agent and then dried for later use.

[0034] The nano-SiO2 filler and the nano-Al2O3 filler are treated with a vinyl silane coupling agent to improve their compatibility with the organosilicon matrix, prevent agglomeration, and enhance cohesive strength.

[0035] 2) Adhesive formulation: 100 parts of the high vinyl silicone oil, 140 parts of the MQ silicone resin, 5 parts of the treated nano-SiO2 filler, 10 parts of the treated nano-Al2O3 filler, 0.5 parts of the anchoring agent and 2.5 parts of the antistatic agent are dispersed evenly at high speed in a planetary mixer to form the main agent. Then, 12 parts of the hydrogen-based polysiloxane crosslinking agent are added, and the mixture is stirred evenly at medium and low speeds and then degassed under vacuum to obtain the adhesive solution.

[0036] 3) Substrate treatment: A transparent polyester film with a thickness of 50μm and an elastic modulus of 4.2GPa is selected as the substrate. A thin layer of silane coupling agent is first coated on its corona-treated surface by microgravure coating and dried at 100℃ for 30 seconds to form a base coating.

[0037] 4) Coating and curing: The adhesive solution obtained in step 2) is coated onto the base layer formed in step 3), and the wet film thickness is controlled to be 50 μm. Then, the coated film is placed in a hot air circulating oven and cured at 145°C for 100 seconds to form an organosilicon pressure-sensitive adhesive layer with a dry film thickness of 25 μm. The protective film is then rolled up to obtain the finished product.

[0038] Low-temperature curing can reduce the damage of high temperature to the ITO conductive layer, while ensuring that the silicone pressure-sensitive adhesive layer is fully cross-linked.

[0039] This application employs a multi-layer coating process, first applying the primer layer and then the silicone pressure-sensitive adhesive layer. The primer layer greatly enhances the adhesion between the silicone pressure-sensitive adhesive layer and the polyester film substrate, preventing interlayer peeling of the protective film during use or peeling. This is a key process detail for improving product reliability.

[0040] Example 3 A method for preparing a pressure-sensitive adhesive protective film for ITO glass, comprising the following steps: 1) Pretreatment: The nano-SiO2 filler and the nano-Al2O3 filler are surface treated with vinyl silane coupling agent and then dried for later use.

[0041] The nano-SiO2 filler and the nano-Al2O3 filler are treated with a vinyl silane coupling agent to improve their compatibility with the organosilicon matrix, prevent agglomeration, and enhance cohesive strength.

[0042] 2) Adhesive formulation: 140 parts of the high vinyl silicone oil, 100 parts of the MQ silicone resin, 12 parts of the treated nano-SiO2 filler, 4 parts of the treated nano-Al2O3 filler, 0.5 parts of the anchoring agent and 2.5 parts of the antistatic agent are dispersed evenly at high speed in a planetary mixer to form the main agent. Then, 12 parts of the hydrogen-based polysiloxane crosslinking agent are added, and the mixture is stirred evenly at medium and low speeds and then degassed under vacuum to obtain the adhesive solution.

[0043] 3) Substrate treatment: A transparent polyester film with a thickness of 50μm and an elastic modulus of 4.2GPa is selected as the substrate. A thin layer of silane coupling agent is first coated on its corona-treated surface by microgravure coating and dried at 80℃ for 40 seconds to form a base coating.

[0044] 4) Coating and curing: The adhesive solution obtained in step 2) is coated onto the base layer formed in step 3), and the wet film thickness is controlled to be 50 μm. Then, the coated film is placed in a hot air circulating oven and cured at 150°C for 90 seconds to form an organosilicon pressure-sensitive adhesive layer with a dry film thickness of 25 μm. The protective film is then rolled up to obtain the finished product.

[0045] Low-temperature curing can reduce the damage of high temperature to the ITO conductive layer, while ensuring that the silicone pressure-sensitive adhesive layer is fully cross-linked.

[0046] This application employs a multi-layer coating process, first applying the primer layer and then the silicone pressure-sensitive adhesive layer. The primer layer greatly enhances the adhesion between the silicone pressure-sensitive adhesive layer and the polyester film substrate, preventing interlayer peeling of the protective film during use or peeling. This is a key process detail for improving product reliability.

[0047] Performance parameters of a pressure-sensitive adhesive protective film for ITO glass Examples 1-3 demonstrate the comprehensive advantages of the technical solution of the present invention. Through the synergistic modification of the nano-SiO2 filler and nano-Al2O3 filler and the design of the high-modulus organosilicon matrix, the anti-friction test performance is good while maintaining excellent flexibility and adhesion, achieving the "anti-scratch" target. At the same time, the optimized crosslinking density and low-temperature curing process ensure moderate peel force (6-11 gf / in) and clean peeling. The addition of the antistatic agent keeps the surface resistance at the level of 10^9 Ω, effectively suppressing the peel voltage to below 100V, which is far lower than the industry's common 200V risk threshold, meeting the requirements for antistatic and low peel line voltage. The high light transmittance (>91%) and low haze (<1.0%) meet the optical application standards.

[0048] Compared with existing technologies, this invention provides a pressure-sensitive adhesive protective film for ITO glass and its preparation method. This method, through an innovative material formulation system and refined process design, manufactures a protective film that solves the defects of existing pressure-sensitive adhesive protective films used on ITO glass. While ensuring excellent scratch resistance, it achieves extremely low tear voltage, controllable and stable moderate adhesion and high light transmittance, and meets the special adhesion requirements of ITO glass surfaces. Moreover, the process temperature is mild, which is suitable for the needs of modern precision electronic manufacturing.

[0049] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A pressure-sensitive adhesive protective film for ITO glass, comprising a polyester film substrate and an organosilicon pressure-sensitive adhesive layer coated on its surface, characterized in that, The silicone pressure-sensitive adhesive layer is formed by coating and curing a mixture; The mixture comprises 90-150 parts of high vinyl silicone oil, 90-150 parts of MQ silicone resin, 10-14 parts of hydrogen-based polysiloxane crosslinking agent, 5-12 parts of nano-SiO2 filler, 4-10 parts of nano-Al2O3 filler, 0.2-0.8 parts of anchoring agent, and 2-3 parts of antistatic agent. The vinyl content of the high vinyl silicone oil is 0.5 mmol / g to 1.2 mmol / g.

2. The pressure-sensitive adhesive protective film for ITO glass according to claim 1, characterized in that, The thickness of the polyester film substrate is 25μm~100μm, and its elastic modulus is not less than 4.0Gpa.

3. The pressure-sensitive adhesive protective film for ITO glass according to claim 1, characterized in that, The average particle size of the nano-SiO2 filler is 10nm~50nm.

4. The pressure-sensitive adhesive protective film for ITO glass according to claim 1, characterized in that, The average particle size of the nano-Al2O3 filler is 20nm~80nm.

5. The pressure-sensitive adhesive protective film for ITO glass according to claim 1, characterized in that, The antistatic agent contains 2% organosilicon surfactant.

6. The pressure-sensitive adhesive protective film for ITO glass according to claim 1, characterized in that, The pressure-sensitive adhesive protective film requires plasma treatment of the ITO glass surface before use.

7. A pressure-sensitive adhesive protective film for ITO glass according to claim 6, characterized in that, The surface energy of the ITO glass after plasma treatment is greater than 79 mJ / m.

8. The method for preparing a pressure-sensitive adhesive protective film for ITO glass as described in claim 1, characterized in that, The specific steps include: 1) Pretreatment: The nano-SiO2 filler and the nano-Al2O3 filler are surface-treated with vinyl silane coupling agent and then dried for later use; 2) Adhesive preparation: The high vinyl silicone oil, the MQ silicone resin, the treated nano SiO2 filler, the treated nano Al2O3 filler, the anchoring agent and the antistatic agent are dispersed evenly at high speed in a planetary mixer to form the main agent. Then the hydrogen-based polysiloxane crosslinking agent is added, and the mixture is stirred at medium and low speed until it is evenly mixed. After vacuum degassing, the adhesive solution is obtained. 3) Substrate treatment: On the corona-treated surface of the polyester film substrate, a thin layer of silane coupling agent is first coated by microgravure coating, and then dried at 80~120℃ for 20~40 seconds to form a base coating. 4) Coating and curing: The adhesive solution obtained in step 2) is coated onto the base layer formed in step 3), and the wet film thickness is controlled to be 50 μm. Then, the coated film is placed in a hot air circulating oven and cured at 140~150℃ for 90~110 seconds to form an organosilicon pressure-sensitive adhesive layer with a dry film thickness of 25 μm. The protective film is then rolled up to obtain the finished product.

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