Silica gel protective film easy to paste and stable in viscidity and preparation method of silica gel protective film

Abstract

The invention provides a silica gel protective film easy to paste and stable in viscidity and a preparation method thereof. The silica gel protective film easy to paste and stable in viscidity is composed of a PET film and a modified silica gel pressure-sensitive adhesive. The prepared silica gel protective film is produced by coating in a thousand-level dust-free room environment, has the characteristics of high cleanliness, easiness in forming and the like, has excellent weather resistance, high stripping precision, no adhesive residue after stripping and good exhaust property, is applied to bottom protection in the original graphite die cutting process and surface protection of bright black or matte black single-sided adhesive in the graphite die cutting process, and has a wide application prospect. And the foam surface is attached for protection in the foam die cutting process.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of protective films, in particular to an easy-to-apply and stable-adhesion silicone protective film and a preparation method thereof. BACKGROUND

[0002] In today's technology and industry, protective films are widely used in the surface protection of various materials, glass, plastic, metal, etc., especially in the protection of touch panel glass. With the rapid development of electronic equipment, optical products and other industries, the performance requirements of protective films are becoming higher and higher. Easy-to-peel PET acrylic protective films with good exhaust performance have become important products to meet the needs of modern industry due to their excellent peelability, exhaust performance, and weather resistance.

[0003] The development of protective films can be traced back to early simple packaging materials. With the continuous progress of industrial technology, the types and performance of protective films are constantly enriched and improved. In the process of the rise and development of the electronics industry, the requirements for protective films are more stringent. Early protective films mainly focused on basic protection functions such as preventing scratches and dust contamination. However, with the miniaturization, refinement, and high performance of electronic products, higher requirements are placed on the performance of protective films, such as easy peelability, exhaust performance, weather resistance, and anti-static performance. In the graphite die-cutting process, silicone protective film can be used as a bottom protection material to prevent graphite sheets from being damaged during die-cutting. In the graphite die-cutting process, when attaching bright black or matte black single-sided adhesive, silicone protective film can be used as a surface protection material to prevent single-sided adhesive from being contaminated and damaged. In the foam die-cutting process, when attaching foam, silicone protective film can be used as a surface protection material to prevent foam from being contaminated and damaged.

[0004] The limitations of traditional protective films, traditional protective films often have residual glue when peeled off, which not only affects the surface quality of the protected material, but also increases the subsequent cleaning work and reduces production efficiency. In addition, poor peelability of protective films can also bring inconvenience to users when replacing them, affecting the user experience of the product. During the attachment of the protective film, if the exhaust performance is not good, air bubbles are likely to be generated, affecting the attachment effect and appearance quality of the protective film. These air bubbles not only affect the visual effect, but also may reduce the protective performance of the protective film, and even cause damage to the protected material. In some high-temperature environments, traditional protective films are prone to softening, deformation, or even loss of protection. For example, in the manufacturing process of electronic devices, high-temperature welding processes may be involved, which requires the protective film to have good weather resistance to ensure that it can effectively protect the protected material in high-temperature environments.

[0005] To solve the problems of existing technology, the present application aims to solve the problems of unstable peel force, residual glue after peeling, poor exhaust performance, and insufficient weather resistance of protective films on the market. SUMMARY

[0006] The application aims to provide an easy-to-paste and stable-adhesion silica gel protective film and a preparation method thereof to solve the problems of unstable peeling force, residual glue after peeling, poor air exhaust performance and insufficient weather resistance of the protective film on the market.

[0007] The technical scheme of the application is as follows:

[0008] An easy-to-paste and stable-adhesion silica gel protective film, characterized in that the easy-to-paste and stable-adhesion silica gel protective film comprises a PET base material and a modified silica gel pressure-sensitive adhesive.

[0009] Further, the raw materials for preparing the silica gel pressure-sensitive adhesive include modified polysiloxane resin, MQ silicone resin and additives.

[0010] Further, the raw materials for preparing the modified polysiloxane resin include polysiloxane, methyltrimethoxysilane, methoxy polyethylene glycol methyl acrylate, methacryloyloxyethyl trimethyl ammonium chloride, N-phenyl maleimide and dibenzoyl peroxide.

[0011] Further, the mass ratio of the polysiloxane, methyltrimethoxysilane, methoxy polyethylene glycol methyl acrylate, methacryloyloxyethyl trimethyl ammonium chloride, N-phenyl maleimide and dibenzoyl peroxide is 40-60:5-12:8-15:4-10:6-12:0.5-2.

[0012] Further, the additive is a mixture of platinum gold catalyst, polysiloxane, epoxy silane and vinyl silane.

[0013] The preparation of the modified polysiloxane resin comprises the following steps:

[0014] S1: an appropriate amount of solvent is added into a reaction container provided with a stirrer, a reflux condenser and a thermometer;

[0015] S2: the polysiloxane is weighed and slowly added into the solvent in step S1, heated to 80-100 DEG C and stirred to fully dissolve the polysiloxane and form a uniform solution;

[0016] S3: the methyltrimethoxysilane, methoxy polyethylene glycol methyl acrylate, methacryloyloxyethyl trimethyl ammonium chloride and N-phenyl maleimide are sequentially added into step S2, after uniform stirring, the dibenzoyl peroxide is added, the temperature is raised to 90-120 DEG C, and the polymerization reaction is carried out under nitrogen protection for 6-12 hours;

[0017] S4: after the reaction is completed, the temperature is cooled to room temperature, and the solvent is removed by reduced pressure distillation to obtain the modified polysiloxane resin.

[0018] Furthermore, the PET film is one of Toray T60, Nitto RP301, and DuPont Teijin PE.

[0019] Furthermore, the preparation method of the modified silicone pressure-sensitive adhesive is as follows: at room temperature, the modified polysiloxane resin, MQ silicone resin, and an auxiliary agent are added into a reactor equipped with a stirrer, and stirred uniformly to obtain the modified silicone pressure-sensitive adhesive.

[0020] Furthermore, the mass ratio of the modified polysiloxane resin, MQ silicone resin and auxiliary agent is 2.5-3:1:0.5-1.

[0021] The present application also provides a method for preparing an easy-to-apply, stable-adhesion silicone protective film, which is characterized by comprising the following steps:

[0022] (1) applying a modified silicone pressure-sensitive adhesive on one side of a PET substrate using a coating machine to prepare a substrate with the modified silicone pressure-sensitive adhesive;

[0023] (2) Finally, the surface of the modified silicone pressure-sensitive adhesive is covered with a release film, dried, cooled, and rolled up to obtain the easy-to-apply, stable-adhesion silicone protective film.

[0024] Furthermore, the thickness of the modified silicone pressure-sensitive adhesive applied in step (1) is 25 to 40 μm; and the drying temperature in step (2) is 50 to 70° C.

[0025] The prepared easy-to-apply and stable adhesive silicone protective film has an adhesiveness of less than 1g, 0.5-1.5g, 1.5-2.5g, 2.5-3.5g, a thickness of 55-80 μm, and a structure of single layer or double layer.

[0026] The present invention provides a silicone protective film that is easy to apply and has stable adhesion. Ether bond groups are introduced into the polysiloxane resin, so that the pressure-sensitive adhesive can form a relatively weak bond with a certain degree of adhesion when in contact with the protected material. When peeling is required, the presence of the ether bond makes it easy to break the bond between the pressure-sensitive adhesive and the protected material, thereby achieving the easy-to-peel property; the polysiloxane resin has suitable viscosity and fluidity. When laminating, it can better adapt to the microscopic undulations on the surface of the protected material, allowing air to be discharged, further enhancing the exhaust performance; imide groups are introduced into the polysiloxane resin. The imide group has high thermal stability and rigidity, and can maintain the stability of the molecular structure at high temperatures, thereby improving the weather resistance of the pressure-sensitive adhesive. The isocyanate curing agent undergoes a cross-linking reaction with the polysiloxane resin to form a three-dimensional network structure. This cross-linking structure can improve the cohesion and heat resistance of the pressure-sensitive adhesive, making the protective film less likely to soften and flow at high temperatures, and maintaining good performance.

[0027] Beneficial effects:

[0028] The present invention provides a silicone protective film that is easy to apply and has stable adhesion. The silicone protective film is coated and produced in a Class 1000 clean room environment. It has the characteristics of high cleanliness and easy molding. It has excellent weather resistance, high peeling precision, no residual glue after peeling, and good exhaust performance. It is used for bottom protection in the original graphite die-cutting process, surface protection of bright black or matte black single-sided adhesive in the graphite die-cutting process, and foam surface protection in the foam die-cutting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Attachment Figure 1 This is a diagram of the structure of the easy-to-apply, stable-adhesion silicone protective film. DETAILED DESCRIPTION

[0030] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention and are not intended to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0031] The commercially available polysiloxane pressure-sensitive adhesive was purchased from Hubei Longsheng Sihai New Materials Co., Ltd., with a model number of sh-916; the commercially available MQ silicone resin pressure-sensitive adhesive was purchased from Hubei Longsheng Sihai New Materials Co., Ltd., with a model number of sh-5201.

[0032] Unless otherwise specified, the chemical reagents used in the present invention are all commercially available analytical grade.

[0033] Preparation of modified polysiloxane resin A:

[0034] S1: Add 1 L of dichloromethane to a reaction vessel equipped with a stirrer, reflux condenser, and thermometer;

[0035] S2: Weigh 4 kg of polysiloxane and slowly add it to the solvent in step S1, heat it to 80°C and stir to fully dissolve the polysiloxane to form a uniform solution;

[0036] S3: 1 kg of methyltrimethoxysilane, 1.5 kg of methoxypolyethylene glycol methacrylate, 0.5 kg of methacryloyloxyethyltrimethylammonium chloride, and 1 kg of N-phenylmaleimide were added to step S2 in sequence, stirred evenly, and then 0.1 kg of dibenzoyl peroxide was added. The temperature was raised to 120° C. and a polymerization reaction was carried out under nitrogen protection for 10 hours.

[0037] S4: After the reaction is completed, the mixture is cooled to room temperature and the solvent is removed by distillation under reduced pressure to obtain a polysiloxane resin.

[0038] Preparation of modified polysiloxane resin B:

[0039] The difference between this preparation and the preparation of modified polysiloxane resin A is that: 1 kg of methyltrimethoxysilane, 1.5 kg of methoxy polyethylene glycol methacrylate, 0.5 kg of methacryloyloxyethyl trimethyl ammonium chloride and 1 kg of N-phenylmaleimide in step S3 are sequentially added to step S2, stirred evenly, and then 0.1 kg of dibenzoyl peroxide is added and replaced with 0.5 kg of methyltrimethoxysilane, 0.8 kg of methoxy polyethylene glycol methacrylate, 1 kg of methacryloyloxyethyl trimethyl ammonium chloride and 1.2 kg of N-phenylmaleimide and other monomers are sequentially added to step S2, stirred evenly, and then 0.2 kg of dibenzoyl peroxide is added.

[0040] Preparation of modified polysiloxane resin C:

[0041] The difference between this preparation and the preparation of modified polysiloxane resin A is that 1 kg of N-phenylmaleimide in step S3 is replaced by 0.5 kg of N-phenylmaleimide.

[0042] Preparation of modified polysiloxane resin D:

[0043] The difference between this preparation and the preparation of modified polysiloxane resin A is that 1.5 kg of methoxy polyethylene glycol methacrylate in step S3 is replaced by 0.5 kg of methoxy polyethylene glycol methacrylate.

[0044] Preparation of modified silicone pressure-sensitive adhesive A:

[0045] At room temperature, 25 kg of modified polysiloxane resin A, 10 kg of MQ silicone resin, 1 kg of platinum catalyst, 1 kg of polysiloxane, 2 kg of epoxy silane, and 2 kg of vinyl silane were added into a reactor equipped with a stirrer and stirred uniformly to obtain modified silicone pressure-sensitive adhesive A.

[0046] Preparation of modified silicone pressure-sensitive adhesive B:

[0047] The difference between this preparation and the preparation of modified silicone pressure-sensitive adhesive A is that 25 kg of modified polysiloxane resin A is replaced by 25 kg of modified polysiloxane resin B.

[0048] Preparation of modified silicone pressure-sensitive adhesive C:

[0049] The difference between this preparation and the preparation of modified silicone pressure-sensitive adhesive A is that 25 kg of modified polysiloxane resin A is replaced by 25 kg of modified polysiloxane resin C.

[0050] Preparation of modified silicone pressure-sensitive adhesive D:

[0051] The difference between this preparation and the preparation of modified silicone pressure-sensitive adhesive A is that 25 kg of modified polysiloxane resin A is replaced by 25 kg of modified polysiloxane resin D.

[0052] Preparation of modified silicone pressure-sensitive adhesive E:

[0053] The difference between this preparation and the preparation of modified silicone pressure-sensitive adhesive A is that 25 kg of modified polysiloxane resin A is replaced by 10 kg of modified polysiloxane resin A.

[0054] Preparation method of easy-to-apply, stable adhesive silicone protective film:

[0055] (1) applying a modified silicone pressure-sensitive adhesive on one side of a PET substrate using a coating machine to prepare a substrate with the modified silicone pressure-sensitive adhesive;

[0056] (2) Finally, a release film is covered on the surface of the modified silicone pressure-sensitive adhesive, dried in an environment of 60° C., cooled, and rolled up to obtain the 0.008×10×10 cm easy-to-apply, stable adhesive silicone protective film.

[0057] Example 1:

[0058] (1) Using a coating machine, a modified silicone pressure-sensitive adhesive A was applied to one side of a PET substrate (Toray T60) to a thickness of 25 μm to prepare a substrate with a modified silicone pressure-sensitive adhesive;

[0059] (2) Finally, the surface of the modified silicone pressure-sensitive adhesive is covered with a silicone oil release layer, dried in an environment of 60° C., then cooled and rolled up to obtain the easy-to-apply, stable-adhesion silicone protective film.

[0060] Example 2:

[0061] The difference between this preparation example and Example 1 is that the modified silicone pressure-sensitive adhesive A is replaced by modified silicone pressure-sensitive adhesive B.

[0062] Example 3:

[0063] The difference between this preparation example and Example 1 is that the modified silicone pressure-sensitive adhesive A is replaced by modified silicone pressure-sensitive adhesive C.

[0064] Example 4:

[0065] The difference between this preparation example and Example 1 is that the modified silicone pressure-sensitive adhesive A is replaced by modified silicone pressure-sensitive adhesive D.

[0066] Example 5:

[0067] The difference between this preparation example and Example 1 is that the modified silicone pressure-sensitive adhesive A is replaced by modified silicone pressure-sensitive adhesive E.

[0068] Comparative Example 1:

[0069] The difference between this preparation example and Example 1 is that the modified silicone pressure-sensitive adhesive A is replaced by a commercially available polysiloxane pressure-sensitive adhesive.

[0070] Comparative Example 2:

[0071] The difference between this preparation example and Example 1 is that the modified silicone pressure-sensitive adhesive is replaced with commercially available MQ silicone resin pressure-sensitive adhesive.

[0072] Performance test experiment:

[0073] 1. Peel force accuracy test:

[0074] Test material preparation: 0.008×10×10 cm silicone protective film samples prepared in Examples 1-5 and Comparative Examples 1-2, respectively, a 0.02×10×20 cm glass substrate, and a WAW-J300 high-precision tensile testing machine.

[0075] Test steps: Adhere one end of the silicone protective film to a glass substrate. Use a pressure roller to evenly roll the surface of the protective film five times to eliminate bubbles and ensure good adhesion. Secure the test plate with the protective film to the lower fixture of the tensile testing machine, and clamp the free end of the protective film in the upper fixture. Perform the peel test at a speed of 300 mm / min, and record the force changes during the peeling process. Perform at least three tests on each sample, and take the average value as the peel force value for that sample. Peel force accuracy is generally expressed in terms of standard deviation. A smaller standard deviation indicates less dispersion in the test results and higher accuracy. Generally speaking, the standard deviation should not exceed 10% of the mean.

[0076] 2. Exhaust test:

[0077] Test material preparation: 0.008×10×10 cm silicone protective film samples prepared in Examples 1-5 and Comparative Examples 1-2, and 0.02×10×10 cm flat and smooth glass plates for testing.

[0078] Test Procedure: Clean the glass surface, ensuring it is clean and free of dust and impurities that could affect the test results. Remove the release liner from the PET acrylic protective film. Gently place the adhesive side of the film over the test plate, slowly lowering it from one end to minimize air bubbles. If the film has good air venting properties, it will automatically expel any air as it is lowered, forming a tight fit against the test plate without noticeable air bubbles. Observe the fit between the film and the test plate, and record the number of bubbles after two minutes; fewer bubbles indicate good air venting properties.

[0079] 3. Weather resistance test:

[0080] Test material preparation: 0.008×10×10 cm silicone protective film samples prepared in Examples 1-5 and Comparative Examples 1-2, high temperature and high humidity test chamber.

[0081] Test steps: Place the test sample in a high-temperature, high-humidity test chamber, set the chamber temperature to 60°C and the relative humidity to 98%, and maintain this temperature for 7 days. After the holding time, remove the test sample and conduct a mechanical property test using a universal tensile testing machine, recording the time when fracture begins.

[0082] Table 1: Test results

[0083] Material Peel force standard deviation / % Number of bubbles Stretching without breaking time (h) Example 1 6 0 28 Example 2 5 0 26 Example 3 7 0 20 Example 4 9 0 24 Example 5 10 2 19 Comparative Example 1 16 5 8 Comparative Example 2 14 3 12

[0084] From the above data, it can be seen that Examples 1-2 show that the easy-to-apply, stable-adhesion silicone protective film has high peeling force precision, good exhaust performance, and excellent weather resistance; Example 3 is compared with Example 1 to show that when preparing the modified silicone pressure-sensitive adhesive, when the N-phenylmaleimide in the polysiloxane resin is too little, the weather resistance of the prepared protective film will be reduced; Example 4 is compared with Example 1 to show that when preparing the modified silicone pressure-sensitive adhesive, when the methoxy polyethylene glycol methacrylate in the polysiloxane resin is too little, the peeling force precision of the prepared protective film will be reduced; Example 5 is compared with Example 1 to show that when preparing the modified silicone pressure-sensitive adhesive, When the mass ratio of the modified polysiloxane resin, MQ silicone resin and auxiliary agent is unreasonable, the peeling force accuracy of the prepared protective film will be reduced, the exhaust will be unclean, and the weather resistance will deteriorate; Comparative Example 1 shows that replacing the modified silicone pressure-sensitive adhesive A with the commercially available polysiloxane pressure-sensitive adhesive will result in a decrease in the peeling force accuracy of the prepared protective film, unclean exhaust, and poor weather resistance, and the expected effect will not be achieved; Comparative Example 2 shows that replacing the modified silicone pressure-sensitive adhesive with the commercially available MQ silicone resin pressure-sensitive adhesive will result in a decrease in the peeling force accuracy of the prepared protective film, unclean exhaust, and poor weather resistance, and the expected effect will not be achieved.

[0085] The present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A silicone protective film that is easy to apply and has stable adhesion, characterized in that: The easy-to-apply and stable-adhesion silicone protective film comprises a PET substrate and a modified silicone pressure-sensitive adhesive.

2. The easy-to-apply, stable-adhesion silicone protective film according to claim 1, characterized in that: The raw materials for preparing the silicone pressure-sensitive adhesive include modified polysiloxane resin, MQ silicone resin and auxiliary agents.

3. The easy-to-apply, stable-adhesion silicone protective film according to claim 1, characterized in that: The raw materials for preparing the modified polysiloxane resin include: polysiloxane, methyltrimethoxysilane, methoxy polyethylene glycol methacrylate, methacryloyloxyethyl trimethyl ammonium chloride, N-phenylmaleimide, and dibenzoyl peroxide; the mass ratio of the polysiloxane, methyltrimethoxysilane, methoxy polyethylene glycol methacrylate, methacryloyloxyethyl trimethyl ammonium chloride, N-phenylmaleimide, and dibenzoyl peroxide is 40-60:5-12:8-15:4-10:6-12:0.5-2.

4. The easy-to-apply, stable-adhesion silicone protective film according to claim 2, characterized in that: The auxiliary agent is a mixture of platinum catalyst, polysiloxane, epoxy silane and vinyl silane.

5. The easy-to-apply, stable-adhesion silicone protective film according to claim 3, characterized in that: The preparation of the modified polysiloxane resin comprises the following steps: S1: Add an appropriate amount of solvent to a reaction vessel equipped with a stirrer, reflux condenser and thermometer; S2: Weigh polysiloxane and slowly add it to the solvent in step S1, heat it to 80-100°C and stir to fully dissolve the polysiloxane to form a uniform solution; S3: adding methyltrimethoxysilane, methoxypolyethylene glycol methacrylate, methacryloyloxyethyltrimethylammonium chloride, and N-phenylmaleimide to step S2 in sequence, stirring evenly, adding dibenzoyl peroxide, raising the temperature to 90-120° C., and carrying out polymerization reaction under nitrogen protection for 6-12 hours; S4: After the reaction is completed, the mixture is cooled to room temperature and the solvent is removed by distillation under reduced pressure to obtain a modified polysiloxane resin.

6. The easy-to-apply, stable-adhesion silicone protective film according to claim 1, characterized in that: The PET film is one of Toray T60, Nitto RP301, and DuPont Teijin PE.

7. The easy-to-apply, stable-adhesion silicone protective film according to claim 1, characterized in that: The preparation method of the modified silicone pressure-sensitive adhesive comprises the following steps: adding modified polysiloxane resin, MQ silicone resin and an auxiliary agent into a reactor equipped with a stirrer at room temperature, and stirring the mixture uniformly.

8. The easy-to-apply, stable-adhesion silicone protective film according to claim 2 or 7, characterized in that: The mass ratio of the modified polysiloxane resin, the MQ silicone resin and the auxiliary agent is 2.5-3:1:0.5-1.

9. The method for preparing the easy-to-apply, stable-adhesion silicone protective film according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) applying a modified silicone pressure-sensitive adhesive on one side of a PET substrate using a coating machine to prepare a substrate with the modified silicone pressure-sensitive adhesive; (2) Finally, the surface of the modified silicone pressure-sensitive adhesive is covered with a release film, dried, cooled, and rolled up to obtain the easy-to-apply, stable-adhesion silicone protective film.

10. The method for preparing the easy-to-apply and stable adhesive silicone protective film according to claim 9, characterized in that: The thickness of the modified silicone pressure-sensitive adhesive applied in step (1) is 25 to 40 μm; and the drying temperature in step (2) is 50 to 70° C.

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