A reusable composite release film and preparation method thereof

Abstract

The present invention provides a reusable composite release film, the release film is a composite film, the composite film includes a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains porous aerogel microspheres, the thickness of the silicone rubber layer is 0.05-0.1mm, the thickness of the PET layer is 0.05-0.1mm, and the particle size of the aerogel microspheres is 200-400 meshes. The release film of the present invention adopts the form of a two-layer composite film, the two layers of the composite film have different degrees of hardness, the silicone rubber layer is softer, the PET layer is harder, and the softer layer fits the carbon fiber, so that the release film has a better peeling effect.

Description

Technical Field

[0001] The invention relates to the field of release film preparation, and in particular to a reusable composite release film and a preparation method thereof. Background Art

[0002] Carbon fiber prepreg is a mid- and downstream product of the carbon fiber industry. It is made of carbon fiber, resin matrix and release paper, etc., and is processed through multiple processes such as coating, hot pressing, cooling, laminating and curling. It has the characteristics of high strength, low density, good plasticity, corrosion resistance and long life. Carbon fiber prepreg has a wide range of applications. It was first used in the field of sports and leisure, but due to its high cost of use, carbon fiber prepreg is currently mainly used in the aerospace field as a structural material for aircraft.

[0003] Release paper is also called isolation paper or anti-adhesive paper. It is a kind of anti-adhesive paper that prevents the prepreg from sticking and protects the prepreg from contamination. Different organic pressure-sensitive adhesives, such as hot melt adhesives, pressure adhesives and rubber system pressure-sensitive adhesives, require different release forces of release paper. According to the different viscosity of the organic pressure-sensitive adhesive to be isolated, the release force should be adjusted accordingly to achieve an extremely light and stable effect when peeling.

[0004] Release paper is widely used in the prepreg production process. In the hot melt method of producing prepreg, the produced resin will be evenly coated on the surface of the release paper and peeled off at the right time. During this period, the release paper is an important carrier for the support, protection and heat transfer of the resin product. However, the mainstream release paper manufacturers currently used in the prepreg industry have low independent control capabilities in the fields of base paper and release agents. The performance levels of products on the market vary greatly, and there are few optional brands. In addition, the release paper is generally discarded after the prepreg production is completed and cannot be reused. Summary of the invention

[0005] Technical problem to be solved: The purpose of the present invention is to provide a reusable composite release film, which is in the form of a two-layer composite film. The two layers of the composite film have different degrees of hardness. The silicone rubber layer is softer and the PET layer is harder. The softer layer fits the carbon fiber, so that the release film has a better peeling effect.

[0006] Technical solution: A reusable composite release film, the release film is a composite film, the composite film includes a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains porous aerogel microspheres, the thickness of the silicone rubber layer is 0.05-0.1mm, the thickness of the PET layer is 0.05-0.1mm, and the particle size of the aerogel microspheres is 200-400 mesh.

[0007] The method for preparing the above-mentioned reusable composite release film comprises the following steps:

[0008] S1. Select two liquid silicone rubbers with different high and low viscosities, dissolve the two liquid silicone rubbers in n-heptane to prepare a low-viscosity silicone rubber solution with a mass fraction of 3-5% and a high-viscosity silicone rubber solution with a mass fraction of 10-14%;

[0009] S2. Adding aerogel microspheres to a low-viscosity silicone rubber solution at a concentration of 3-5%, ultrasonically stirring, adding the silicone rubber solution to a high-viscosity silicone rubber solution at a concentration of 10-14%, ultrasonically stirring until uniformly dispersed, degassing, casting into a film, placing the film in a ventilated place to volatilize the solvent, and curing the film of the volatilized solvent to obtain a silicone rubber layer;

[0010] S3. Apply adhesive on one side of the silicone rubber layer, and then laminate the PET layer on the silicone rubber layer to obtain a release film.

[0011] Preferably, the viscosities of the high-viscosity and low-viscosity liquid silicone rubbers in step S1 are 5000-7000 MPa•s and 2500-3000 MPa•s, respectively.

[0012] Preferably, in step S2, the mass ratio of the low-viscosity silicone rubber solution, the high-concentration silicone rubber solution and the aerogel microspheres is 2-5:8-12:1-2.

[0013] Preferably, the curing temperature in step S2 is 80-100° C. and the curing time is 10-20 min.

[0014] Beneficial effects: The reusable composite release film of the present invention has the following advantages:

[0015] In the present invention, a composite material is used as a release film, and the release film includes a silicone rubber layer and a PET layer. The hardness of the PET layer is higher than that of the silicone rubber layer. The silicone rubber layer is used as the release layer of the release film, and aerogel microspheres are added to the silicone rubber. Under the action of pressure, the silicone rubber layer will adhere to the carbon fiber prepreg, and the silicone rubber layer will be compressed to a certain extent under the action of pressure. However, since the PET layer is harder and will not be compressed, after the pressure disappears, the silicone rubber layer has a certain rebound, which reduces the bonding force between the release film and the carbon fiber prepreg.

[0016] In the present invention, aerogel microspheres with a particle size of 200-400 mesh are filled in a 0.05-0.1 mm silicone rubber layer. The particle size of the aerogel microspheres can be distributed in the silicone rubber layer in a hierarchical manner, with a portion distributed on the surface of the silicone rubber layer and a portion distributed inside the silicone rubber layer. The aerogel microspheres distributed inside the silicone rubber layer are squeezed by the pressure, and will release the rebound force after the pressure is removed. The aerogel microspheres distributed on the surface of the silicone rubber will make the silicone rubber easier to be peeled off from the carbon fiber surface.

[0017] In the present invention, the thickness of the silicone rubber layer is controlled at 0.05-0.1 mm, and the thickness of the PET layer is controlled at 0.05-0.1 mm. Different resilience is achieved by different thicknesses, so that the release film peeling effect is better;

[0018] In the present invention, low-viscosity liquid silicone rubber and aerogel microspheres are first mixed, and the low-viscosity silicone rubber can better enter the interior of the aerogel particles, reduce the generation of bubbles and hollows after film formation, and improve the peeling effect of the release film. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with embodiments, which are explanations of the present invention and are not limited to the following embodiments:

[0020] Example 1

[0021] A reusable composite release film, the release film is a composite film, the composite film comprises a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains porous aerogel microspheres, the thickness of the silicone rubber layer is 0.05 mm, and the thickness of the PET layer is 0.05 mm;

[0022] The method for preparing the above-mentioned reusable composite release film comprises the following steps:

[0023] S1. Select two liquid silicone rubbers with different high and low viscosities, the viscosity of the high-viscosity liquid silicone rubber is 5000MPa•s, and the viscosity of the low-viscosity liquid silicone rubber is 2500MPa•s, dissolve the two liquid silicone rubbers in n-heptane to prepare a 5% low-viscosity silicone rubber solution and a 14% high-viscosity silicone rubber solution;

[0024] S2. Add aerogel microspheres to the low-viscosity silicone rubber solution, and after ultrasonic stirring, add the silicone rubber solution to the high-viscosity silicone rubber solution. The mass ratio of the low-viscosity silicone rubber solution, the high-concentration silicone rubber solution and the aerogel microspheres is 2:8:1. Ultrasonic stirring is performed until the solution is evenly dispersed. After degassing, the solution is cast into a film. After the film is formed, the solution is placed in a ventilated place to volatilize the solvent. The film of the volatilized solvent is cured at a temperature of 80° C. for 10 minutes to obtain a silicone rubber layer.

[0025] S3. Apply adhesive on one side of the silicone rubber layer, and then laminate the PET layer on the silicone rubber layer to obtain a release film.

[0026] Example 2

[0027] A reusable composite release film, the release film is a composite film, the composite film comprises a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains porous aerogel microspheres, the thickness of the silicone rubber layer is 0.05 mm, and the thickness of the PET layer is 0.1 mm;

[0028] The method for preparing the above-mentioned reusable composite release film comprises the following steps:

[0029] S1. Select two liquid silicone rubbers with different high and low viscosities, the viscosity of the high-viscosity liquid silicone rubber is 7000MPa•s, and the viscosity of the low-viscosity liquid silicone rubber is 3000MPa•s, dissolve the two liquid silicone rubbers in n-heptane to prepare a 3% low-viscosity silicone rubber solution and a 10% high-viscosity silicone rubber solution;

[0030] S2. Add aerogel microspheres to the low-viscosity silicone rubber solution, stir it evenly by ultrasonic, then add the silicone rubber solution to the high-viscosity silicone rubber solution, the mass ratio of the low-viscosity silicone rubber solution, the high-concentration silicone rubber solution and the aerogel microspheres is 5:12:2, stir it evenly by ultrasonic until it is evenly dispersed, cast it into a film after degassing, place it in a ventilated place after the film is formed to volatilize the solvent, and cure the film with the volatilized solvent at a temperature of 100° C. for 20 min to obtain a silicone rubber layer;

[0031] S3. Apply adhesive on one side of the silicone rubber layer, and then laminate the PET layer on the silicone rubber layer to obtain a release film.

[0032] Example 3

[0033] A reusable composite release film, the release film is a composite film, the composite film comprises a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains porous aerogel microspheres, the thickness of the silicone rubber layer is 0.08 mm, and the thickness of the PET layer is 0.1 mm;

[0034] The method for preparing the above-mentioned reusable composite release film comprises the following steps:

[0035] S1. Select two liquid silicone rubbers with different high and low viscosities, the viscosity of the high viscosity liquid silicone rubber is 5500MPa•s, and the viscosity of the low viscosity liquid silicone rubber is 2800MPa•s, dissolve the two liquid silicone rubbers in n-heptane to prepare a low viscosity silicone rubber solution with a mass fraction of 3.5% and a high viscosity silicone rubber solution with a mass fraction of 11%;

[0036] S2. Add aerogel microspheres to the low-viscosity silicone rubber solution, and after ultrasonic stirring, add the silicone rubber solution to the high-viscosity silicone rubber solution. The mass ratio of the low-viscosity silicone rubber solution, the high-concentration silicone rubber solution and the aerogel microspheres is 3:9:1.2. Ultrasonic stirring is performed until the solution is evenly dispersed. After degassing, the solution is cast into a film. After the film is formed, the solution is placed in a ventilated place to volatilize the solvent. The film of the volatilized solvent is cured at a temperature of 85° C. for 10 minutes to obtain a silicone rubber layer.

[0037] S3. Apply adhesive on one side of the silicone rubber layer, and then laminate the PET layer on the silicone rubber layer to obtain a release film.

[0038] Example 4

[0039] A reusable composite release film, the release film is a composite film, the composite film comprises a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains porous aerogel microspheres, the thickness of the silicone rubber layer is 0.05 mm, and the thickness of the PET layer is 0.1 mm;

[0040] The method for preparing the above-mentioned reusable composite release film comprises the following steps:

[0041] S1. Select two liquid silicone rubbers with different high and low viscosities, the viscosity of the high-viscosity liquid silicone rubber is 6500MPa•s, and the viscosity of the low-viscosity liquid silicone rubber is 2800MPa•s, dissolve the two liquid silicone rubbers in n-heptane to prepare a low-viscosity silicone rubber solution with a mass fraction of 4.5% and a high-viscosity silicone rubber solution with a mass fraction of 13%;

[0042] S2. Add aerogel microspheres to the low-viscosity silicone rubber solution, and after ultrasonic stirring, add the silicone rubber solution to the high-viscosity silicone rubber solution. The mass ratio of the low-viscosity silicone rubber solution, the high-concentration silicone rubber solution and the aerogel microspheres is 4:11:1.8. Ultrasonic stirring is performed until the solution is evenly dispersed. After degassing, the solution is cast into a film. After the film is formed, the solution is placed in a ventilated place to volatilize the solvent. The film of the volatilized solvent is cured at a temperature of 95° C. for 20 minutes to obtain a silicone rubber layer.

[0043] S3. Apply adhesive on one side of the silicone rubber layer, and then laminate the PET layer on the silicone rubber layer to obtain a release film.

[0044] Example 5

[0045] A reusable composite release film, the release film is a composite film, the composite film comprises a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains porous aerogel microspheres, the thickness of the silicone rubber layer is 0.08 mm, and the thickness of the PET layer is 0.1 mm;

[0046] The method for preparing the above-mentioned reusable composite release film comprises the following steps:

[0047] S1. Select two liquid silicone rubbers with different high and low viscosities, the viscosity of the high-viscosity liquid silicone rubber is 6000MPa•s, and the viscosity of the low-viscosity liquid silicone rubber is 2600MPa•s, dissolve the two liquid silicone rubbers in n-heptane to prepare a 4% low-viscosity silicone rubber solution and a 12% high-viscosity silicone rubber solution;

[0048] S2. Add aerogel microspheres to the low-viscosity silicone rubber solution, stir evenly with ultrasound, then add the silicone rubber solution to the high-viscosity silicone rubber solution, the mass ratio of the low-viscosity silicone rubber solution, the high-concentration silicone rubber solution and the aerogel microspheres is 3.5:10:1.5, stir evenly with ultrasound until dispersed, degas and cast into a film, place the film in a ventilated place to volatilize the solvent, and cure the film of the volatilized solvent at a temperature of 90° C. for 15 min to obtain a silicone rubber layer;

[0049] S3. Apply adhesive on one side of the silicone rubber layer, and then laminate the PET layer on the silicone rubber layer to obtain a release film.

[0050] Comparative Example 1

[0051] A reusable release film, the release film is supported by a silicone rubber layer and porous aerogel microspheres, and the thickness of the silicone rubber layer is 0.12 mm;

[0052] The method for preparing the above-mentioned reusable release film comprises the following steps:

[0053] S1. Select two liquid silicone rubbers with different high and low viscosities, the viscosity of the high-viscosity liquid silicone rubber is 7000MPa•s, and the viscosity of the low-viscosity liquid silicone rubber is 3000MPa•s, dissolve the two liquid silicone rubbers in n-heptane to prepare a 3% low-viscosity silicone rubber solution and a 10% high-viscosity silicone rubber solution;

[0054] S2. Add aerogel microspheres to the low-viscosity silicone rubber solution, stir it evenly by ultrasonic, then add the silicone rubber solution to the high-viscosity silicone rubber solution. The mass ratio of the low-viscosity silicone rubber solution, the high-concentration silicone rubber solution and the aerogel microspheres is 5:12:2. Stir it evenly by ultrasonic until it is evenly dispersed. After degassing, cast it into a film. After the film is formed, place it in a ventilated place to allow the solvent to evaporate. Cure the film with the evaporated solvent at a curing temperature of 100°C for 20 minutes to obtain a silicone rubber layer.

[0055] Comparative Example 2

[0056] A reusable composite release film, the release film is a composite film, the composite film comprises a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains porous aerogel microspheres, the thickness of the silicone rubber layer is 0.1 mm, and the thickness of the PET layer is 0.02 mm;

[0057] The method for preparing the above-mentioned reusable composite release film comprises the following steps:

[0058] S1. Select two liquid silicone rubbers with different high and low viscosities, the viscosity of the high-viscosity liquid silicone rubber is 7000MPa•s, and the viscosity of the low-viscosity liquid silicone rubber is 3000MPa•s, dissolve the two liquid silicone rubbers in n-heptane to prepare a 3% low-viscosity silicone rubber solution and a 10% high-viscosity silicone rubber solution;

[0059] S2. Add aerogel microspheres to the low-viscosity silicone rubber solution, stir it evenly by ultrasonic, then add the silicone rubber solution to the high-viscosity silicone rubber solution, the mass ratio of the low-viscosity silicone rubber solution, the high-concentration silicone rubber solution and the aerogel microspheres is 5:12:2, stir it evenly by ultrasonic until it is evenly dispersed, cast it into a film after degassing, place it in a ventilated place after the film is formed to volatilize the solvent, and cure the film with the volatilized solvent at a temperature of 100° C. for 20 min to obtain a silicone rubber layer;

[0060] S3. Apply adhesive on one side of the silicone rubber layer, and then laminate the PET layer on the silicone rubber layer to obtain a release film.

[0061] Comparative Example 3

[0062] A reusable composite release film, the release film is a composite film, the composite film comprises a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains SiO2 microspheres, the average particle size of the SiO2 microspheres is 150 meshes, the thickness of the silicone rubber layer is 0.3 mm, and the thickness of the PET layer is 0.1 mm;

[0063] The method for preparing the above-mentioned reusable composite release film comprises the following steps:

[0064] S1. Select two liquid silicone rubbers with different high and low viscosities, the viscosity of the high-viscosity liquid silicone rubber is 7000MPa•s, and the viscosity of the low-viscosity liquid silicone rubber is 3000MPa•s, dissolve the two liquid silicone rubbers in n-heptane to prepare a 3% low-viscosity silicone rubber solution and a 10% high-viscosity silicone rubber solution;

[0065] S2. Add SiO2 microspheres to the low-viscosity silicone rubber solution, stir evenly by ultrasonic, then add the silicone rubber solution to the high-viscosity silicone rubber solution, the mass ratio of the low-viscosity silicone rubber solution, the high-concentration silicone rubber solution and the SiO2 microspheres is 5:12:2, stir evenly by ultrasonic until dispersed, cast into a film after degassing, place the film in a ventilated place to volatilize the solvent, and cure the film with the volatilized solvent at a temperature of 100°C for 20 minutes to obtain a silicone rubber layer;

[0066] S3. Apply adhesive on one side of the silicone rubber layer, and then laminate the PET layer on the silicone rubber layer to obtain a release film.

[0067] Comparative Example 4

[0068] A reusable composite release film, the release film is a composite film, the composite film comprises a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains porous aerogel microspheres, the thickness of the silicone rubber layer is 0.1 mm, and the thickness of the PET layer is 0.1 mm;

[0069] The method for preparing the above-mentioned reusable composite release film comprises the following steps:

[0070] S1. Select two liquid silicone rubbers with different high and low viscosities, the viscosity of the high-viscosity liquid silicone rubber is 7000MPa•s, and the viscosity of the low-viscosity liquid silicone rubber is 3000MPa•s, dissolve the two liquid silicone rubbers in n-heptane to prepare a 3% low-viscosity silicone rubber solution and a 10% high-viscosity silicone rubber solution;

[0071] S2. Add aerogel microspheres to the low-viscosity silicone rubber solution, stir it evenly by ultrasonic, then add the silicone rubber solution to the high-viscosity silicone rubber solution, the mass ratio of the low-viscosity silicone rubber solution, the high-concentration silicone rubber solution and the aerogel microspheres is 5:12:2, stir it evenly by ultrasonic until it is evenly dispersed, cast it into a film after degassing, place it in a ventilated place after the film is formed to volatilize the solvent, and cure the film with the volatilized solvent at a temperature of 100° C. for 20 min to obtain a silicone rubber layer;

[0072] S3. Apply adhesive on one side of the silicone rubber layer, and then laminate the PET layer on the silicone rubber layer to obtain a release film.

[0073] The particle sizes of the porous aerogel microspheres prepared in Examples 1-5 are shown in the following table:

[0074] Average particle size (mesh) Example 1 282 Example 2 286 Example 3 323 Example 4 369 Example 5 345

[0075] Performance Testing:

[0076] A resin film is introduced to the upper surface of the carbon fiber prepreg through an unwinding device, and a release film is introduced to the upper surface of the resin film. The unwinding tension of the resin film is controlled between 10 and 20N, the unwinding tension of the release paper is controlled between 10 and 20N, the viscosity of the resin film is 80Pa·s, the prepreg pressure is controlled at 2MPa, and the prepreg speed is controlled at 2.5m / min. The molded epoxy resin / carbon fiber prepreg and the release film are demoulded, and the demoulding peeling force is tested. The specific results are shown in the following table:

[0077] <![CDATA[Peeling force / (N·25mm -1 )]]> Example 1 1.99 Example 2 2.25 Example 3 2.17 Example 4 2.19 Example 5 2.20 Comparative Example 1 3.69 Comparative Example 2 3.98 Comparative Example 3 2.56 Comparative Example 4 3.01

[0078] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A reusable composite release film, characterized in that: The release film is a composite film, comprising a silicone rubber layer and a PET layer, the silicone rubber layer and the PET layer are composited with an adhesive, the silicone rubber layer contains porous aerogel microspheres, the thickness of the silicone rubber layer is 0.05-0.1 mm, the thickness of the PET layer is 0.05-0.1 mm, and the particle size of the aerogel microspheres is 200-400 meshes; The method for preparing the reusable composite release film comprises the following steps: S1. Select two liquid silicone rubbers with different high and low viscosities, dissolve the two liquid silicone rubbers in n-heptane to prepare a low-viscosity silicone rubber solution with a mass fraction of 3-5% and a high-viscosity silicone rubber solution with a mass fraction of 10-14%; S2. Adding aerogel microspheres to a low-viscosity silicone rubber solution at a concentration of 3-5%, ultrasonically stirring, adding the silicone rubber solution to a high-viscosity silicone rubber solution at a concentration of 10-14%, ultrasonically stirring until uniformly dispersed, degassing, casting into a film, placing the film in a ventilated place to volatilize the solvent, and curing the film of the volatilized solvent to obtain a silicone rubber layer; S3. Apply adhesive on one side of the silicone rubber layer, and then laminate the PET layer on the silicone rubber layer to obtain a release film.

2. The reusable composite release film according to claim 1, characterized in that: The viscosities of the high-viscosity and low-viscosity liquid silicone rubbers in step S1 are 5000-7000 MPa•s and 2500-3000 MPa•s, respectively.

3. The reusable composite release film according to claim 1, characterized in that: In the step S2, the mass ratio of the low viscosity silicone rubber solution, the high viscosity silicone rubber solution and the aerogel microspheres is 2-5:8-12:1-2.

4. The reusable composite release film according to claim 1, characterized in that: The curing temperature in step S2 is 80-100° C. and the curing time is 10-20 min.