Radiation-curable silicone release film coating compositions, coatings, and applications

Abstract

The present application relates to the technical field of radiation curing materials, and in particular to a radiation curing silicone release film coating composition, a coating and a preparation method thereof.The coating composition comprises the following raw materials in parts by weight: 60-90 parts of non-functionalized polysiloxane, 10-30 parts of side-chain acrylate modified free-radical polymerizable siloxane, and 1-10 parts of 1,6-bistrimethoxysilane.The cured film obtained has ultralow release force (3 g / 25 mm or less), excellent aged release force (70 degrees for 48 hours, 5 g / 25 mm or less), high residual tack (70 degrees for 20H, 92% or more), and good anchorage, and is suitable for use in the fields of food paper (baking and packaging), adhesive labels and adhesive tapes, functional films, and the like, and is particularly suitable for use in the field of automated die-cutting OCA optical adhesive products.The preparation method of the coating is simple, no VOC is emitted during the preparation process, environmental pollution is avoided, the operation risk is reduced, and the coating has a significant environmental protection advantage.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation-curable materials, and in particular to a radiation-curable organic silicon release film coating composition, a coating and a preparation method thereof. Background Art

[0002] Release films, also known as isolation films, peeling films, and separation films, are known by a variety of names. Common release film products are surface-treated substrates, including coatings with silicone release agents, fluorine release agents, or plasma treatment, to impart a light yet stable release force to various adhesive materials. Based on release force, they can be categorized as light, medium, and heavy release films, with release forces typically ranging from 5g to 2000g. Structurally, they can be categorized as adhesive release films, composite release films, laser films, and adhesive-free release films. Functionally, they can be categorized as isolation release films, protective release films, waterproof release films, light-diffusing release films, printed release films, and tape release films. Release film is now widely used in packaging, printing, silk screen printing, pad printing, nameplates, membrane switches, flexible circuits, insulation products, circuit boards, laser anti-counterfeiting, lamination, electronics, sealing material films, reflective materials, waterproof materials, medicine (plaster paper), sanitary paper, adhesive products, die-cutting and punching processing and other industries.

[0003] Release films are primarily categorized by their curing method: traditional heat-curing technology and modern radiation-curing technology. Traditional heat-curing technology has the following main drawbacks: 1. Curing requires high temperatures (above 100°C), resulting in high energy consumption, long curing times, and low efficiency. 2. The system's high viscosity necessitates the addition of large amounts of organic solvents for proper coating, which in turn generates significant amounts of organic solvents during the production process and pollutes the environment. Modern radiation-curing involves the rapid conversion of liquid materials to solid form using photon sources (such as ultraviolet and gamma radiation) or electron sources (such as electron beams). Radiation-curing technology offers the five advantages of "E": economical, efficient, environmentally friendly, energy-saving, and enabling, making it more environmentally friendly and efficient than traditional heat-curing technology. Commonly used radiation-curing methods in industry are ultraviolet (UV) curing and electron beam (EB) curing, which utilize highly efficient energy sources to initiate rapid curing. For example, UV curing means that under ultraviolet light irradiation, the photoinitiator in the system absorbs ultraviolet light to form excited molecules, which decompose to produce active free radicals or ions. These free radicals or ions further initiate the polymerization of unsaturated monomers and prepolymers, thereby instantly transforming the system from a low-viscosity liquid to a solid material.

[0004] OCA optical adhesive is an adhesive material used for the assembly of optical display devices (such as liquid crystal displays). Its main function is to bond the different layers of the display device (such as liquid crystal panels and glass panels) together to provide better optical performance and viewing experience. In the process of automated high-speed production, die-cutting is an important process. When die-cutting OCA optical adhesive products, in order to meet the needs of automated high-speed production, the original light release film for the coating and production of OCA optical adhesive must be switched to an ultra-light release film suitable for automated high-speed die-cutting process, and the aging release force is also required to be no more than 5g / 25mm. The aging release force refers to the peeling force between the release film and the OCA optical adhesive after long-term use, which needs to be controlled within a certain range to ensure the performance and life of the product. However, when preparing the release film, the existing technology generally uses a large amount of acrylate-modified silicone resin with polar groups, which results in a large peeling force of the release film and cannot meet the requirements of the performance index of the aging release force.

[0005] Therefore, it is necessary to develop new materials or improve existing technologies to meet the performance requirements of release film materials for automated high-speed die-cutting processes. Summary of the Invention

[0006] In response to the above-mentioned problems existing in the prior art, the applicant of the present invention provides a radiation-curable silicone release film coating composition, a coating and a preparation method thereof.

[0007] The radiation-curable silicone release film coating composition of the present invention adopts solvent-free electron beam (EB) curing technology and has no VOC emissions. The formed cured film has ultra-low peel force (less than 3g / 25mm), excellent aged release force (less than 5g / 25mm after 48 hours at 70 degrees), high residual adhesion (more than 92% after 20 hours at 70 degrees), and good anchoring properties. It is suitable for food paper (baking and packaging), adhesive labels and tapes, functional films and other fields, and is particularly suitable for the field of automated die-cutting OCA optical adhesive products.

[0008] A first aspect of the present application is to provide a radiation-curable silicone release film coating composition.

[0009] The specific technical solutions are as follows:

[0010] A radiation-curable silicone release film coating composition comprises the following raw materials in parts by weight:

[0011] 60-90 parts of non-functional polysiloxane,

[0012] 10-30 parts of side chain acrylate modified free radical polymerizable siloxane,

[0013] 1-10 parts of 1,6-bistrimethoxysilylalkane.

[0014] Furthermore, the non-functionalized polysiloxane has a linear siloxane main chain and an aliphatic or aromatic substituent, and its structural formula is shown in Formula 1:

[0015]

[0016] In Formula 1, R1, R2, R3, R4 and R5 are independently selected from alkyl groups and aryl groups, wherein m and n are integers, and m and n are not zero at the same time.

[0017] Furthermore, the non-functionalized polysiloxane is a linear material having a siloxane backbone with aliphatic or aromatic substituents, wherein R1, R2, R3, R4 and R5 in Formula 1 are independently selected from alkyl groups, wherein m and n are integers, and m and n are not both zero;

[0018] In some embodiments, the non-functionalized polysiloxane is a linear material having a siloxane backbone with aliphatic or aromatic substituents, wherein R1, R2, R3, R4, and R5 in Formula 1 are all methyl groups, wherein m and n are integers, and m and n are not both zero.

[0019] Furthermore, the non-functionalized polysiloxane is a fluid having an appropriate molecular weight and a dynamic viscosity at 25°C of 20,000 mPa.s-30,000 mPa.s; 30,000 mPa.s-60,000 mPa.s; 60,000 mPa.s-80,000 mPa.s; 80,000 mPa.s-100,000 mPa.s; the fluid with an appropriate molecular weight is used to limit the non-functionalized polysiloxane to ensure that its viscosity is within a certain range.

[0020] Furthermore, the non-functionalized polysiloxane is a fluid with an appropriate molecular weight, and its dynamic viscosity at 25° C. is 30,000 mPa.s-50,000 mPa.s; 50,000 mPa.s-60,000 mPa.s; 60,000 mPa.s-80,000 mPa.s.

[0021] When the dynamic viscosity of the non-functionalized polysiloxane at 25°C is lower than 20,000 mPa.s, the coating after EB curing cannot meet the ultra-low peel force requirements; when the dynamic viscosity of the non-functionalized polysiloxane at 25°C is greater than 100,000 mPa.s, the system compatibility is poor and phase separation occurs, resulting in the coating having an orange peel appearance and cannot be tested normally.

[0022] In some embodiments, the non-functionalized polysiloxane is selected from one or more of PMX200-30000cst, PMX200-40000cst, PMX200-50000cst, PMX200-60000cst, PMX200-70000cst, and PMX200-80000cst produced by Dow Corning.

[0023] Furthermore, the side chain acrylate modified free radical polymerizable siloxane has a straight chain siloxane main chain and has a hydrocarbon group and an acryloyl group as substituents, and the structural formula is shown in Formula 2:

[0024]

[0025] In Formula 2, R1, R2, R3 and R5 are independently selected from alkyl groups and aryl groups, and R4 is CH2=CH-C(O)-O-CH2-CH(OH)-CH2-O-(CH2)6-, wherein m is an integer from 1 to 50; and n is an integer from 1 to 10.

[0026] Furthermore, the 1,6-bistrimethoxysilylalkane is 1,6-bistrimethoxysilylhexane.

[0027] The second aspect of the present application is to provide a method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0028] 60-90 parts of non-functionalized polysiloxane, 10-30 parts of side chain acrylate-modified free radical polymerizable siloxane, and 1-10 parts of 1,6-bistrimethoxysilylalkane are mixed and stirred and uniformly dispersed to prepare the radiation-curable organic silicone release film coating composition.

[0029] Furthermore, the dispersion method uses a high-speed disperser;

[0030] Furthermore, the speed of the disperser is 1000-3000 rpm, and the dispersion time is 20-40 minutes.

[0031] A third aspect of the present application is to provide a method for preparing a radiation-curable silicone release film coating, using the coating composition described above or the coating composition prepared by the preparation method described above, the preparation method comprising the following steps:

[0032] S11: first, a wire rod is used to apply the radiation-curable silicone release film coating composition on the corona-charged PET film to form a liquid coating with a thickness of 0.5 to 1.5 μm;

[0033] S12: The PET film coated with the liquid coating obtained in S11 is then placed in an electron beam curing device for radiation curing to obtain a silicone release film coating.

[0034] In one embodiment, electron beam (EB) curing is used in step S12;

[0035] Furthermore, in step S12, the EB curing conditions are: voltage 50KeV-150KeV, and dosage 20KGy-120KGy.

[0036] The fourth aspect of the present application is to provide an application of a thin film coating composition, characterized in that the coating composition can form a dry film and a cured product after EB curing, and is used in the preparation of food paper, adhesive labels and adhesive tapes, functional films and other fields; the food paper includes but is not limited to baking paper and packaging paper.

[0037] Furthermore, it is applied to the automated die-cutting of OCA optical adhesive products.

[0038] Beneficial effects:

[0039] The beneficial effects of this application are:

[0040] The radiation-curable silicone release film coating composition provided in this application has a cured film prepared with ultra-low peeling force (less than 3g / 25mm) and excellent aged release force (less than 5g / 25mm at 70 degrees for 48 hours); it also has high residual adhesion (more than 92% at 70 degrees for 20 hours) and good anchoring properties, and is suitable for food paper (baking and packaging), adhesive labels and tapes, functional films and other fields, and is particularly suitable for the field of automated die-cutting OCA optical adhesive products.

[0041] The radiation-curable silicone release film coating provided in the present application has a simple preparation method, no VOC emissions during the preparation process, avoids environmental pollution, and also reduces operational risks, thus having significant environmental advantages.

[0042] The present invention orients non-functionalized polysiloxane toward the coating surface, orients 1,6-bistrimethoxysilylalkane toward the substrate side, and uses side-chain acrylate-modified free radical polymerizable siloxane as an intermediary of the microscopic system. Electron beam curing is used to overcome the defect that non-functionalized polysiloxane cannot participate in the reaction in conventional curing methods, thereby preparing a release film with ultra-low peel force, excellent aging release force and good anchoring properties. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] Performance testing method:

[0045] (1) Peel force test

[0046] Test instrument: Tensile tester or similar instrument, with a fixture capable of peeling pressure-sensitive materials at 180°, a peeling speed of 300 mm / min, an accuracy of ±2%, and a test plate made of smooth stainless steel. One standard pressure roller (2 kg);

[0047] Test sample: It should be a test strip taken from a representative material, with a width of 25mm; at least 200mm long along the instrument direction, with a clean and straight cut. At least 3 strips of each material should be tested. The test tape should be TESA7475.

[0048] Test conditions: temperature 23℃±2℃, 50%RH±5%RH;

[0049] Test steps: Place the TESA7475 adhesive strip facing downward and apply it to a clean test panel with light finger pressure. Use a roller to press back and forth twice at a speed of approximately 10 mm / s to ensure close contact between the adhesive and the test panel. After the test strip is applied, let it sit for 20 minutes before testing again. Adjust the peel angle to 180°, set the speed to 300 mm / min, and start the test.

[0050] Test results: The peel force is expressed in g / 25mm, and the average value is taken for each test strip.

[0051] (2) Aging release force test

[0052] Test instrument: Tensile tester or similar instrument, with a fixture capable of peeling pressure-sensitive materials at 180°, a peeling speed of 300 mm / min, an accuracy of ±2%, and a test plate made of smooth stainless steel. One standard pressure roller (2 kg);

[0053] Test sample: It should be a test strip taken from a representative material, with a width of 25mm; at least 200mm long along the instrument direction, with a clean and straight cut. At least 3 strips of each material should be tested. The test tape should be TESA7475.

[0054] Test conditions: temperature 23℃±2℃, 50%RH±5%RH;

[0055] Test steps: With the TESA7475 adhesive side facing down, apply the strip to a clean test panel with light finger pressure. Use a roller to press back and forth twice at approximately 10 mm / s to ensure close contact between the adhesive and the test panel. After the test strip is adhered, age it at 70°C under the pressure of a 2 kg standard weight for 48 hours. Then, cool it for 0.5 to 2 hours at room temperature (23±2°C) and 50% relative humidity before retesting. Adjust the peel angle to 180°, set the speed to 300 mm / min, and start the test.

[0056] Test results: The aging peel force is expressed in g / 25mm, and the average value is taken for each test strip.

[0057] (3) Residual adhesion test

[0058] Test instrument: Tensile tester or similar instrument, with a fixture capable of peeling pressure-sensitive materials at 180°, a peeling speed of 300 mm / min, an accuracy of ±2%, and a test plate made of smooth stainless steel. One standard pressure roller (2 kg);

[0059] Test sample: should be a test strip taken from a representative material; at least 200mm long along the instrument direction, with a clean and straight cut. At least 3 strips of each material should be tested. The test tape used should be Nitto 31B.

[0060] Test conditions: temperature 23℃±2℃, 50%RH±5%RH;

[0061] Test steps:

[0062] 1. Apply Nitto 31B 25mm wide tape to the test sample and roll it back and forth twice with a 2kg roller. Then age it at 70℃ under the pressure of a 2kg standard weight for 20 hours. Then, cool it for 0.5-2 hours at room temperature (23±2℃) and relative humidity (50%) and peel it off at 180° at 300mm / min. Each set of samples should have at least 3 tapes.

[0063] 2. Stick the Nitto 31B tape peeled off in step 1 on a stainless steel plate again. Place it under 2 kg pressure at room temperature (23±2°C) and relative humidity (50%) for 2 hours. Then peel it 180° at 300 mm / min. Take the average value and record it as L1.

[0064] 3. Apply standard Nitto 31B tape to a stainless steel plate and roll it back and forth twice with a 2kg roller. Place it under 2kg pressure at room temperature (23±2℃) and relative humidity (50%) for 2 hours. Then peel it off at 180° at 300mm / min. The average value is recorded as L0.

[0065] Test result: L1÷L0×100% is the residual adhesion.

[0066] (4) Anchorage test

[0067] Place the test sample in a constant temperature and humidity chamber at 60°C and 90% RH for 7 days, then cool it down at room temperature of 23±2°C and relative humidity of 50% for 0.5 to 2 hours. Rub the coating vigorously 10 times with your fingers to confirm the coating anchoring property:

[0068] 1. O indicates very good anchoring performance, with no fogging or shedding of the coating;

[0069] 2.△ indicates general anchoring performance, the coating does not fall off, but fogging occurs;

[0070] 3.× indicates poor anchoring and the coating is peeling off.

[0071] The present invention is described in detail below. The raw materials and amounts of the raw materials used in each example are shown in Table 1.

[0072] Table 1 Distribution ratio of each group in the embodiment

[0073]

[0074] * Side chain acrylate modified free radical polymerizable siloxanes were prepared by the method described in US Pat. No. 6,548,568B1 by hydrosilylation of hydrogen siloxanes having side chain Si—H groups with allyl glycidyl ether, followed by ring opening with acrylic acid.

[0075] Example 1

[0076] A method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0077] 85 parts of non-functionalized polysiloxane (PMX200-50000cst produced by Dow Corning), 10 parts of side chain acrylate-modified free radical polymerizable siloxane (m=20, and n=5), and 5 parts of 1,6-bistrimethoxysilylhexane were stirred and dispersed at a speed of 2000 rpm using a disperser for 30 minutes to prepare the radiation-curable silicone release film coating composition.

[0078] The method for preparing the coating comprises the following steps:

[0079] S11: first, a radiation-curable silicone release film coating composition is coated on the corona-charged PET film using a wire rod to form a liquid coating with a thickness of 0.8 μm;

[0080] S12: The PET film containing the liquid coating is then placed in an electron beam (EB) curing device for radiation curing (EB curing conditions: voltage 110 KeV, dose 80 KGy), thereby preparing a radiation-cured silicone release film coating.

[0081] The corona-treated PET film can form a fine corona discharge area on the surface, which can enhance the surface tension, increase the roughness and improve the surface energy, making the PET film more suitable for various processing processes.

[0082] Example 2

[0083] A method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0084] 75 parts of non-functionalized polysiloxane (PMX200-50000cst produced by Dow Corning), 20 parts of side chain acrylate-modified free radical polymerizable siloxane (m=20, and n=5), and 5 parts of 1,6-bistrimethoxysilylhexane were stirred and dispersed at a speed of 2000 rpm using a disperser for 30 minutes to prepare the radiation-curable silicone release film coating composition.

[0085] The method for preparing the coating comprises the following steps:

[0086] S11: first, a radiation-curable silicone release film coating composition is coated on the corona-charged PET film using a wire rod to form a liquid coating with a thickness of 0.8 μm;

[0087] S12: The PET film containing the liquid coating is then placed in an electron beam (EB) curing device for radiation curing (EB curing conditions: voltage 110 KeV, dose 70 KGy), thereby preparing a radiation-cured silicone release film coating.

[0088] Example 3

[0089] A method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0090] 65 parts of non-functionalized polysiloxane (PMX200-50000cst produced by Dow Corning), 30 parts of side chain acrylate-modified free radical polymerizable siloxane (m=20, and n=5), and 5 parts of 1,6-bistrimethoxysilylhexane were stirred and dispersed at a speed of 2000 rpm using a disperser for 30 minutes to prepare the radiation-curable silicone release film coating composition.

[0091] The method for preparing the coating comprises the following steps:

[0092] S11: first, a radiation-curable silicone release film coating composition is coated on the corona-charged PET film using a wire rod to form a liquid coating with a thickness of 0.8 μm;

[0093] S12: The PET film containing the liquid coating is then placed in an electron beam (EB) curing device for radiation curing (EB curing conditions: voltage 110 KeV, dose 60 KGy), thereby preparing a radiation-cured silicone release film coating.

[0094] Example 4

[0095] A method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0096] 85 parts of non-functionalized polysiloxane (PMX200-30000cst produced by Dow Corning), 10 parts of side chain acrylate-modified free radical polymerizable siloxane (m=20, and n=5), and 5 parts of 1,6-bistrimethoxysilylhexane were stirred and dispersed at a speed of 2000 rpm using a disperser for 30 minutes to prepare the radiation-curable silicone release film coating composition.

[0097] The method for preparing the coating comprises the following steps:

[0098] S11: first, a radiation-curable silicone release film coating composition is coated on the corona-charged PET film using a wire rod to form a liquid coating with a thickness of 0.8 μm;

[0099] S12: The PET film containing the liquid coating is then placed in an electron beam (EB) curing device for radiation curing (EB curing conditions: voltage 110 KeV, dose 80 KGy), thereby preparing a radiation-cured silicone release film coating.

[0100] Example 5

[0101] A method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0102] 65 parts of non-functionalized polysiloxane (PMX200-80000cst produced by Dow Corning), 30 parts of side chain acrylate-modified free radical polymerizable siloxane (m=20, and n=5), and 5 parts of 1,6-bistrimethoxysilylhexane were stirred and dispersed in a disperser at a speed of 2000 rpm for 30 minutes to prepare the radiation-curable silicone release film coating composition.

[0103] The method for preparing the coating comprises the following steps:

[0104] S11: first, a radiation-curable silicone release film coating composition is coated on the corona-charged PET film using a wire rod to form a liquid coating with a thickness of 0.8 μm;

[0105] S12: The PET film containing the liquid coating is then placed in an electron beam (EB) curing device for radiation curing (EB curing conditions: voltage 110 KeV, dose 80 KGy), thereby preparing a radiation-cured silicone release film coating.

[0106] Example 6

[0107] A method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0108] 75 parts of non-functionalized polysiloxane (PMX200-50000cst produced by Dow Corning), 20 parts of side chain acrylate-modified free radical polymerizable siloxane (m=40, and n=7), and 5 parts of 1,6-bistrimethoxysilylhexane were stirred and dispersed at a speed of 2000 rpm using a disperser for 30 minutes to prepare the radiation-curable silicone release film coating composition.

[0109] The method for preparing the coating comprises the following steps:

[0110] S11: first, a radiation-curable silicone release film coating composition is coated on the corona-charged PET film using a wire rod to form a liquid coating with a thickness of 0.8 μm;

[0111] S12: The PET film containing the liquid coating is then placed in an electron beam (EB) curing device for radiation curing (EB curing conditions: voltage 110 KeV, dose 80 KGy), thereby preparing a radiation-cured silicone release film coating.

[0112] Comparative Example 1

[0113] A method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0114] 95 parts of non-functionalized polysiloxane (PMX200-50000cst produced by Dow Corning), 5 parts of side chain acrylate-modified free radical polymerizable siloxane (m=20, and n=5), and 0 parts of 1,6-bistrimethoxysilylhexane were stirred and dispersed at a speed of 2000 rpm using a disperser for 30 minutes to prepare the radiation-curable silicone release film coating composition.

[0115] The method for preparing the coating comprises the following steps:

[0116] S11: first, a radiation-curable silicone release film coating composition is coated on the corona-charged PET film using a wire rod to form a liquid coating with a thickness of 0.8 μm;

[0117] S12: The PET film containing the liquid coating is then placed in an electron beam (EB) curing device for radiation curing (EB curing conditions: voltage 110 KeV, dose 80 KGy), thereby preparing a radiation-cured silicone release film coating.

[0118] Comparative Example 2

[0119] A method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0120] 50 parts of non-functionalized polysiloxane (PMX200-50000cst produced by Dow Corning), 40 parts of side chain acrylate-modified free radical polymerizable siloxane (m=20, and n=5), and 10 parts of 1,6-bistrimethoxysilylhexane were stirred and dispersed at a speed of 2000 rpm using a disperser for 30 minutes to prepare the radiation-curable silicone release film coating composition.

[0121] The method for preparing the coating comprises the following steps:

[0122] S11: first, a radiation-curable silicone release film coating composition is coated on the corona-charged PET film using a wire rod to form a liquid coating with a thickness of 0.8 μm;

[0123] S12: The PET film containing the liquid coating is then placed in an electron beam (EB) curing device for radiation curing (EB curing conditions: voltage 110 KeV, dose 80 KGy), thereby preparing a radiation-cured silicone release film coating.

[0124] Comparative Example 3

[0125] A method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0126] 75 parts of non-functionalized polysiloxane (PMX200-5000cst produced by Dow Corning), 20 parts of side chain acrylate-modified free radical polymerizable siloxane (m=20, and n=5), and 5 parts of 1,6-bistrimethoxysilylhexane were stirred and dispersed at a speed of 2000 rpm using a disperser for 30 minutes to prepare the radiation-curable silicone release film coating composition.

[0127] The method for preparing the coating comprises the following steps:

[0128] S11: first, a radiation-curable silicone release film coating composition is coated on the corona-charged PET film using a wire rod to form a liquid coating with a thickness of 0.8 μm;

[0129] S12: The PET film containing the liquid coating is then placed in an electron beam (EB) curing device for radiation curing (EB curing conditions: voltage 110 KeV, dose 80 KGy), thereby preparing a radiation-cured silicone release film coating.

[0130] Comparative Example 4

[0131] A method for preparing a radiation-curable silicone release film coating composition, the preparation method comprising the following steps:

[0132] 75 parts of non-functionalized polysiloxane (PMX200-200000cst produced by Dow Corning), 20 parts of side chain acrylate-modified free radical polymerizable siloxane (m=20, and n=5), and 5 parts of 1,6-bistrimethoxysilylhexane were stirred and dispersed at a speed of 2000 rpm using a disperser for 30 minutes to prepare the radiation-curable silicone release film coating composition.

[0133] The method for preparing the coating comprises the following steps:

[0134] S11: first, a radiation-curable silicone release film coating composition is coated on the corona-charged PET film using a wire rod to form a liquid coating with a thickness of 0.8 μm;

[0135] S12: The PET film containing the liquid coating is then placed in an electron beam (EB) curing device for radiation curing (EB curing conditions: voltage 110 KeV, dose 80 KGy), thereby preparing a radiation-cured silicone release film coating.

[0136] Performance test results:

[0137] The film coatings obtained in Examples 1 to 6 of the present invention and Comparative Examples 1 to 4 were tested for peel strength, aged release force, residual adhesion, and anchoring properties. The test results are shown in Table 2.

[0138] Table 2

[0139]

[0140] From the test results in Table 2, we can see that:

[0141] The thin film coatings prepared in Examples 1 to 6 of the present invention have a peeling force of 1.3-2.7 g / 25 mm, an aging release force of 2.1-4.5 g / 25 mm, and a residual adhesion of more than 95%. They have ultra-low peeling force, excellent aging release force, high residual adhesion, and good anchoring properties, and are particularly suitable for the field of automated die-cutting OCA optical adhesive products. The preparation process has no VOC emissions, is energy-saving and environmentally friendly.

[0142] The film coatings prepared in Comparative Examples 1-4 all failed to meet the required performance. The film coating prepared in Comparative Example 1 exhibited ultra-low peel force and excellent aged release strength, but suffered from poor residual adhesion and anchoring properties. This was due to the lack of 1,6-bistrimethoxysilylhexane and the insufficient amount of side-chain acrylate-modified free-radical polymerizable siloxane. This resulted in poor anchoring properties and a reduced crosslinking density, failing to meet the requirements of conventional release films.

[0143] The film coating prepared in Comparative Example 2 had excellent residual adhesion and good anchoring properties, but both the peel strength and aging release strength deteriorated. This was due to the low amount of non-functionalized polysiloxane added, which failed to meet the requirements of automated die-cutting OCA optical adhesive products.

[0144] The thin film coating prepared in Comparative Example 3 had insufficient crosslinking under EB curing conditions due to the low molecular weight of the non-functionalized polysiloxane, resulting in poor overall performance.

[0145] The thin film coating prepared in Comparative Example 4 had an orange peel appearance and large fluctuations in test values ​​due to the high molecular weight of the non-functionalized polysiloxane, poor system compatibility, and phase separation. This failed to meet the basic requirements of a release film.

[0146] This application utilizes a non-functionalized polysiloxane oriented toward the coating surface and a 1,6-bistrimethoxysilylalkane oriented toward the substrate. A side-chain acrylate-modified free-radical polymerizable siloxane is used as the intermediary in the microstructure. Through EB curing, a release film with ultra-low peel force, high residual adhesion, excellent aging release force, and good anchoring properties is prepared. This release film is particularly suitable for automated die-cutting of OCA optical adhesive products. The preparation method is simple, and the process is VOC-free, avoiding environmental pollution and reducing operational risks, offering significant environmental advantages.

[0147] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A radiation-curable silicone release film coating composition, characterized in that: The raw materials include the following parts by weight: 65-85 parts of non-functional polysiloxane, 15-30 parts of side chain acrylate modified free radical polymerizable siloxane, 1-5 parts of 1,6-bistrimethoxysilylalkane; The non-functionalized polysiloxane has a dynamic viscosity of 30,000-80,000 mPa.s at 25° C.; The side chain acrylate modified free radical polymerizable siloxane has a straight chain siloxane main chain and has a hydrocarbon group and an acryloyl group as substituents, and the structural formula is shown in Formula 2: Formula 2 In Formula 2, R1, R2, R3 and R5 are independently selected from alkyl groups and aryl groups, R4 is CH2=CH-C(O)-O-CH2-CH(OH)-CH2-O-(CH2)6-, wherein m is an integer from 1 to 50; and n is an integer from 1 to 10; The 1,6-bistrimethoxysilylalkane is 1,6-bistrimethoxysilylhexane.

2. The radiation-curable silicone release film coating composition according to claim 1, characterized in that: The non-functionalized polysiloxane has a linear siloxane main chain and an aliphatic or aromatic substituent, and its structural formula is shown in Formula 1: Formula 1 In Formula 1, R1, R2, R3, R4 and R5 are independently selected from alkyl groups and aryl groups, wherein m and n are integers, and m and n are not zero at the same time.

3. The radiation-curable silicone release film coating composition according to claim 1, characterized in that: The non-functionalized polysiloxane is fluid, and its dynamic viscosity at 25° C. is 50,000 mPa.s-60,000 mPa.s, or 60,000 mPa.s-80,000 mPa.s.

4. The method for preparing the radiation-curable silicone release film coating composition according to any one of claims 1 to 3, characterized in that: The steps include: The non-functionalized polysiloxane, the side chain acrylate modified free radical polymerizable siloxane and the 1,6-bistrimethoxysilyl alkane are mixed and stirred and dispersed uniformly to prepare the radiation curing organic silicon release film coating composition.

5. A method for preparing a radiation-curable silicone release film coating, characterized in that: Using the coating composition according to any one of claims 1 to 3 or the coating composition prepared by the preparation method according to claim 4; The preparation method comprises the following steps: S11: first, a wire rod is used to apply the radiation-curable silicone release film coating composition on the corona-treated PET film to form a liquid coating with a thickness of 0.5 to 1.5 μm; S12: The PET film coated with the liquid coating obtained in S11 is then placed in an electron beam curing device for radiation curing to obtain a silicone release film coating.

6. The method for preparing a radiation-curable silicone release film coating according to claim 5, wherein: The electron beam curing conditions in step S12 are: voltage 50 KeV-150 KeV, and dose 20 KGy-120 KGy.

7. Use of the organosilicon release film coating composition according to any one of claims 1 to 3, or use of the organosilicon release film coating composition prepared by the preparation method according to claim 4, characterized in that: It is used in the preparation of food paper, adhesive labels and tapes, and functional films.

8. The use of the organic silicone release film coating composition according to claim 7, characterized in that: Applied to automated die-cutting of OCA optical adhesive products.

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