A mesh release film and a method of making the same

Abstract

The application discloses a grid release film and a preparation method thereof, relates to the technical field of release films, and discloses a grid release film which comprises a film base material and a release layer coated on the surface of the film base material, wherein the film base material is made of PET recycled material which is subjected to hydrolysis treatment and extruded, and the release layer is formed after functional release agent is cured by ultraviolet light radiation, and the functional release agent comprises the following raw materials in parts by weight: 80-110 parts of organic silicon modified polyurethane, 50-75 parts of ethyl acetate, 5-6 parts of a photoinitiator, 15-20 parts of pentaerythritol tetraacrylate, 10-15 parts of nano silicon dioxide, 3-5 parts of an acrylate leveling agent and the like, wherein the organic silicon modified polyurethane is used as the main body to prepare the functional release agent, which is beneficial to the reaction between the functional release agent and the surface of the film base material, and thus the adhesion of the functional release agent on the film base material is improved.

Description

Technical Field

[0001] This invention relates to the technical field of release films, and in particular to a grid release film and its preparation method. Background Technology

[0002] Release film, also known as peeling film, release film, separation film, or protective film, is a thin film substrate coated with a release agent to give it the property of separation. Release films are widely used on plastic surfaces, metal surfaces, automotive product surfaces, and electronic product surfaces.

[0003] PET release film is a type of release film. It involves coating the surface of a PET film substrate with a release agent, forming a release layer on the PET surface, thus giving the PET film substrate a certain release effect. Due to its excellent physical and mechanical properties and good thermal stability, PET release film is currently widely used in packaging, printing, membrane switches, flexible circuits, insulation products, and other processing fields.

[0004] With rapid societal development, PET recycling technology has matured. Currently, there are processes that recycle and granulate waste PET products such as plastic bottles to obtain recycled PET material, which is then used to prepare PET release films. However, because the sources of recycled PET are not entirely identical, the degree of polymerization of PET extracted from different products varies, resulting in a large melt molecular weight distribution and significant melt fluctuations. This not only leads to poor mechanical properties of the resulting PET film substrate but also makes it difficult to uniformly coat the release agent during release film preparation. Furthermore, the poor adhesion between the release agent and the film substrate easily causes interface damage between the release layer and the film substrate, resulting in poor release performance of the prepared release film. Summary of the Invention

[0005] In order to uniformly and fully coat the release agent on the film substrate made from recycled PET material, improve the adhesion between the release agent and the film substrate, and improve the release effect of the release film made from recycled PET material, this application provides a grid release film, its preparation method and processing equipment.

[0006] Firstly, the functional release agent provided in this application adopts the following technical solution:

[0007] A functional release agent for preparing the release layer of a mesh release film, comprising the following raw materials in parts by weight:

[0008] 80-110 parts of silicone-modified polyurethane;

[0009] 50-75 parts of ethyl acetate;

[0010] 5-6 parts of photoinitiator;

[0011] 15-20 parts of pentaerythritol tetraacrylate;

[0012] 10-15 parts of nano-silica;

[0013] 3-5 parts of acrylic leveling agent;

[0014] The organosilicon-modified polyurethane release agent is prepared by modifying polyurethane with either hydroxyl silicone oil or mercapto silicone oil.

[0015] By adopting the above technical solution and using silicone-modified polyurethane as the main component to prepare functional release agents, it is beneficial to enable the functional release agents to react with the surface of the film substrate, thereby improving the adhesion of the functional release agents to the film substrate. Moreover, adding a certain amount of acrylate leveling agent and pentaerythritol tetraacrylate to the functional release agents is beneficial to improving the fluidity of the functional release agents, enabling the functional release agents to be uniformly coated on the surface of the film substrate and forming a uniform release layer, which is beneficial to improving the release effect of the mesh release film.

[0016] Optionally, the organosilicon-modified polyurethane is selected by modifying polyurethane with mercaptosilicone oil, and the preparation steps of the mercaptosilicone oil-modified polyurethane release agent include:

[0017] B1. First, thoroughly mix the polyether polyol, chain extender and diisocyanate, and stir continuously at 65-70℃ for 2-3 hours until the reaction reaches near the theoretical isocyanate value to obtain polyurethane prepolymer.

[0018] B2. Then, the polyurethane prepolymer obtained in B1 is thoroughly mixed with mercapto silicone oil and organotin catalyst, and the mixture is stirred continuously at 65-70℃ for 2-3 hours until the -NCO characteristic peak disappears, thus obtaining mercapto silicone oil modified polyurethane.

[0019] By adopting the above technical solution, using mercapto-modified polyurethane as the main body to prepare functional release agents, it is beneficial to improve the flowability of functional release agents, so that functional release agents can be fully leveled and uniformly coated on film substrates. Moreover, during the ultraviolet radiation curing process, mercapto groups can not only fully react with the abundant hydroxyl groups on the surface of film substrates to improve the bonding strength between functional release agents and film substrates, but also have sulfur atoms, which are more likely to form hydrogen bonds after curing, which is beneficial to further improve the adhesion of functional release agents on film substrates.

[0020] Optionally, the weight ratio of the polyether polyol, the chain extender, and the diisocyanate is 1:(1-3):(0.4-0.6), and the weight ratio of the polyurethane prepolymer, the mercapto silicone oil, and the organotin catalyst is 1:(3-5):(0.1-0.3).

[0021] By adopting the above technical solution and increasing the amount of chain extender added, more opportunities for branching and cross-linking can be provided for the synthesis of mercaptosilicone oil modified polyurethane, so that the prepared organosilicon modified polyurethane can form a certain degree of cross-linking structure, thereby increasing the overall viscosity of organosilicon modified polyurethane. This is beneficial to increasing the surface viscosity of functional release agent. However, the adhesion between functional release agent and film substrate will decrease. Therefore, when the weight ratio between polyether polyol, chain extender and diisocyanate is in the range of 1:(1-3):(0.4-0.6), functional release agent has high surface viscosity and can maintain good adhesion to film substrate.

[0022] Optionally, the polyether polyol is selected by mixing a polyether polyol with a molecular weight of 2000 and a polyether polyol with a molecular weight of 4000, and the polyether polyol with a molecular weight of 2000 and the polyether polyol with a molecular weight of 4000 are mixed at a weight ratio of 1:(3-5).

[0023] By adopting the above technical solution, when polyether polyols with a molecular weight of 2000 and 4000 are mixed in a certain proportion, a certain synergistic effect can be produced. This not only increases the viscosity of the functional release agent and the peeling force of the mesh release film, but also improves the adhesion to the film substrate and the residual adhesion rate of the mesh release film, which is beneficial to make the mesh release film have a better release effect.

[0024] Optionally, the nano-silica is modified nano-silica, and the modification step includes:

[0025] C1. First, vacuum dry the nano-silica, then put the dried nano-silica into toluene and stir it thoroughly, and gradually raise the temperature to 60-80℃. Then add KH590, maintain the temperature and continue stirring for 4-5 hours. Filter the obtained product, wash it several times and then vacuum dry it to finally obtain modified nano-silica.

[0026] By adopting the above technical solution, it is beneficial to improve the dispersibility of nano-silica in functional release agents based on mercapto-modified polyurethane and reduce the agglomeration of nano-silica, which facilitates the uniform coating of the functional release agent on the film substrate. Moreover, the introduced mercapto groups can react with the functional groups on the surface of the film substrate, further improving the adhesion of the functional release agent to the film substrate.

[0027] Optionally, the photoinitiator is photoinitiator 1173.

[0028] By adopting the above technical solution, photoinitiator 1173 is a high-efficiency, non-yellowing ultraviolet photoinitiator, and it has good compatibility with ethyl acetate, which is conducive to its full dispersion in functional release agents and fully initiating their curing.

[0029] Optionally, the photoinitiator 1173 undergoes a thiol-terminated treatment before addition, the thiol-terminated treatment step including:

[0030] D1. Using ethyl acetate as the reaction solvent, first add an appropriate amount of isophorone diisocyanate and an appropriate amount of organotin catalyst to ethyl acetate, stir and mix thoroughly, and then gradually raise the temperature to 65-70℃ under light-protected conditions. Slowly add an appropriate amount of photoinitiator 1173 within 30 minutes, and continue to keep the reaction in the dark until it is close to the theoretical isocyanate value to obtain the isocyanate modified photoinitiator.

[0031] D2. Add an appropriate amount of dimercaprol to the isocyanate-modified photoinitiator obtained in D1, and keep it in the dark at 60-65℃ until the -NCO characteristic peak completely disappears. Finally, remove ethyl acetate by vacuum distillation to obtain thiol-terminated photoinitiator 1173.

[0032] By adopting the above technical solution, thiol groups are introduced at the end of the photoinitiator 1173, which can react with the hydroxyl groups on the surface of the film substrate. This helps to reduce the residue and migration rate of the photoinitiator after curing. Moreover, a large number of thiol groups can also reduce the amount of photoinitiator used in the functional release agent. It has a certain synergistic effect with the photoinitiator, which helps the functional release agent to be fully cured on the surface of the film substrate, and further improves the adhesion of the functional release agent on the film substrate.

[0033] Secondly, the grid release film provided in this application adopts the following technical solution:

[0034] A mesh release film includes a film substrate and a release layer coated on the surface of the film substrate. The film substrate is made by extrusion of hydrolyzed recycled PET material. The release layer is formed by repeatedly coating the film substrate with a functional release agent as described above by an anilox roller and curing it by ultraviolet radiation.

[0035] By adopting the above technical solution, the film substrate is produced by extruding recycled PET material, which is beneficial to improving the environmental friendliness of the mesh release film and has certain environmental significance. Moreover, the functional release agent coated on the film substrate by curing it with ultraviolet light radiation is conducive to the reaction between the functional release agent and the surface of the film substrate, thereby improving the adhesion of the functional release agent on the film substrate and preventing interface damage between the release layer and the film substrate.

[0036] Optionally, the method for preparing the thin film substrate includes:

[0037] A1. Sorting the recycled PET plastic bottles and removing non-PET debris from the surface, thoroughly mixing the PET plastic bottles with a certain amount of water to crush them, and then obtaining PET fragments after multiple washing and filtration.

[0038] A2. Place the PET fragments obtained in A1 into a sodium hydroxide solution of a certain concentration, and maintain the temperature at 200-250℃ and the pressure at 1.4-2.0MPa for 3-5 hours. Then adjust the solution to neutral with hydrochloric acid solution to obtain PET hydrolysate.

[0039] A3. Thoroughly mix 30-35 parts of PET hydrolysate obtained in A2, 2-4 parts of n-butyl acetate, and 1-2 parts of epoxy phosphate, and maintain the temperature at 270-280℃ for 2-3 hours. Then, extrude and granulate to obtain recycled PET material.

[0040] A4. The recycled PET material obtained in A3 is extruded to form a film substrate.

[0041] By adopting the above technical solution, the collected PET plastic bottles are crushed, hydrolyzed, and then re-polymerized. This process helps to ensure that the degree of polymerization of the recycled PET material is similar, the molecular weight distribution of the melt is concentrated, and the melt fluctuation is small. This is beneficial for the preparation and processing of film substrates, and can produce film substrates with uniform and smooth properties. Moreover, the epoxy phosphate backbone contains abundant hydroxyl groups, which helps to improve the adhesion between the functional release agent and the film substrate, allowing the release layer to fully adhere to the film substrate and reducing the likelihood of interfacial damage.

[0042] Thirdly, the method for preparing a mesh release film provided in this application adopts the following technical solution:

[0043] A method for preparing a mesh release film includes the following steps:

[0044] S1. First, use an anilox roller to coat the functional release agent on one side of the film substrate at a coating speed of 3-5 m / min in a light-protected state. The coating thickness is 10-15 μm. Then, place it in a vacuum oven for pre-baking for 1-1.5 h, and then cure it under nitrogen protection by ultraviolet radiation for 150-180 s to obtain a single-layer mesh film.

[0045] S2. The single-layer mesh film obtained in S1 is coated with a coating roller. Under light-protected conditions, the functional release agent is coated again on the release layer formed in S1 at a coating speed of 10-15 m / min. The coating thickness is 5-7 μm. Then, it is placed in a vacuum oven for pre-baking for 1-1.5 h, and then cured with ultraviolet radiation for 150-180 s under nitrogen protection to obtain the mesh release film.

[0046] By adopting the above technical solution, which involves two coating processes (fast and slow), it is beneficial to form release layers of different thicknesses on the film substrate. First, the anilox roller coats the film at a slower speed, forming a thicker grid on the film substrate. The raised grid can reduce the contact area between the release film and the object to a certain extent, making it easier for the release film to be removed from the glass. The second coating is applied quickly to the grid, which helps to maintain the shape of the grid and further thickens the release layer. As a result, the grid release film can maintain a high participation adhesion rate and also has a better release effect.

[0047] In summary, the technical solution of this application has at least one of the following beneficial effects:

[0048] 1. By using silicone-modified polyurethane as the main component to prepare functional release agents, it is beneficial to enable the functional release agents to react with the surface of the film substrate, thereby improving the adhesion of the functional release agents to the film substrate.

[0049] 2. By crushing and hydrolyzing the collected PET plastic bottles and then re-polymerizing them, the degree of polymerization of the recycled PET material is made closer, the molecular weight distribution of the melt is concentrated, and the melt fluctuation is small. This is beneficial to the preparation and processing of film substrates and can produce film substrates with uniform and smooth properties.

[0050] 3. Modifying nano-silica with KH590 can improve the dispersibility of nano-silica in functional release agents based on mercaptosilicone oil-modified polyurethane and reduce the agglomeration of nano-silica, which is beneficial for uniform coating of functional release agents on film substrates. Detailed Implementation

[0051] The present application will be further described in detail below with reference to preparation examples, embodiments and comparative examples.

[0052] The nano-silica was purchased from Bohuas Nanotechnology (Ningbo) Co., Ltd., with the grade Brofos-SiO2 and a density of 2.66 g / cm³. 2 Specific surface area is 154 m² 2 / g.

[0053] The epoxy phosphate was purchased from Tianjin Ruike Chemical Trading Co., Ltd., and its grade is RKZ3008.

[0054] The acrylic leveling agent was purchased from Guangdong Shunde Shibang Jiaming Chemical Co., Ltd., brand name BZ6358N.

[0055] For polyether polyols with a molecular weight of 2000, purchase from Tianjin Sanshi Chemical Co., Ltd., brand name TDB-2000, with a hydroxyl value of 54.5-57.5 and a viscosity of 270-370.

[0056] For polyether polyols with a molecular weight of 4000, purchase from Tianjin Sanshi Chemical Co., Ltd., brand name TDB-4000, with a hydroxyl value of 26.5-29.5 and a viscosity of 850-1150.

[0057] The hydroxyl silicone oil was purchased from Foshan Chuying Chemical Co., Ltd., with the brand name FSCY-6006, a viscosity of 40, and a hydroxyl content of 10%.

[0058] The mercaptosilicone oil was purchased from Shanghai Jiadeer Chemical Technology Co., Ltd., with a viscosity of 100 and a mercapto content of 8%.

[0059] The dimethyl silicone oil was purchased from Dongguan Airui Chemical Co., Ltd., with the grade 201-100 and a viscosity of 100±8.

[0060] Preparation Example

[0061] Preparation Example 1

[0062] A method for preparing a thin film substrate for a mesh release film includes the following steps:

[0063] A1. The recycled PET plastic bottles are sorted and non-PET debris is removed from the surface. The sorted PET plastic bottles and water are mixed and crushed at a weight ratio of 1:1.5. After multiple washing and filtration, PET fragments are obtained.

[0064] A2. Place 10 kg of PET fragments obtained in A1 into 50 kg of sodium hydroxide solution with a concentration of 20% by mass, and maintain the temperature at 250℃ and the pressure at 1.4 MPa for 3 hours. Then adjust the solution to neutral with a concentration of 5% hydrochloric acid solution to obtain PET hydrolysate.

[0065] A3. Thoroughly mix 35kg of PET hydrolysate, 4kg of n-butyl acetate, and 2kg of epoxy phosphate obtained in A2, and maintain the temperature at 270℃ for 3 hours. Then, extrude and granulate to obtain recycled PET material.

[0066] A4. The recycled PET material obtained in A3 is extruded to form a film substrate with a thickness of 50μm.

[0067] Preparation Example 2

[0068] A method for preparing a thin film substrate for a mesh release film includes the following steps:

[0069] A1. The recycled PET plastic bottles are sorted and non-PET debris is removed from the surface. The sorted PET plastic bottles and water are mixed and crushed at a weight ratio of 1:1.5. After multiple washing and filtration, PET fragments are obtained.

[0070] A2. Place 10 kg of PET fragments obtained in A1 into 50 kg of sodium hydroxide solution with a concentration of 20% by mass, and maintain the temperature at 200℃ and the pressure at 2.0 MPa for 5 hours. Then adjust the solution to neutral with a 5% hydrochloric acid solution to obtain PET hydrolysate.

[0071] A3. Mix 30 parts of PET hydrolysate, 2 parts of n-butyl acetate, and 1 part of epoxy phosphate thoroughly, and keep the temperature at 280℃ for 2 hours. Then, extrude and granulate to obtain recycled PET material.

[0072] A4. The recycled PET material obtained in A3 is extruded to form a film substrate with a thickness of 50μm.

[0073] Preparation Example 3

[0074] A method for preparing a thin film substrate for a mesh release film includes the following steps:

[0075] A1. The recycled PET plastic bottles are sorted and non-PET debris is removed from the surface. The sorted PET plastic bottles and water are mixed and crushed at a weight ratio of 1:1.5. After multiple washing and filtration, PET fragments are obtained.

[0076] A2. The PET fragments obtained in A1 are directly melt-extruded to form a film substrate with a thickness of 50μm.

[0077] Example

[0078] Example 1

[0079] A method for preparing a mesh release film includes the following steps:

[0080] S1. First, the functional release agent is coated on one side of the film substrate using an anilox roller coating method under light-protected conditions at a coating speed of 5 m / min. The coating thickness is 12 μm. Then, it is placed in a vacuum oven at 70℃ for pre-baking for 1 hour, and then cured under nitrogen protection by ultraviolet radiation for 180 seconds to obtain a single-layer mesh film.

[0081] S2. The single-layer mesh film obtained in S1 is coated with a coating roller. Under light-protected conditions, the functional release agent is coated again on the release layer formed in S1 at a coating speed of 15 m / min, with a coating thickness of 5 μm. Then, it is placed in a vacuum oven at 70°C for pre-baking for 1 h, and then cured with ultraviolet radiation for 180 s under nitrogen protection to obtain the mesh release film.

[0082] In this embodiment, the thin film substrate is selected from the thin film substrate prepared in Preparation Example 1.

[0083] In this embodiment, the functional release agent is prepared by fully blending the following raw materials by weight: 100 kg of silicone-modified polyurethane, 60 kg of ethyl acetate, 5 kg of photoinitiator 1173, 18 kg of pentaerythritol tetraacrylate, 13 kg of nano silica and 4 kg of acrylate leveling agent.

[0084] The organosilicon-modified polyurethane uses hydroxyl silicone oil-modified polyurethane, and the preparation method of hydroxyl silicone oil-modified polyurethane includes the following steps:

[0085] B1. First, mix the polyether polyol, chain extender and diisocyanate thoroughly in a weight ratio of 1:1:0.6, and stir continuously at 70°C for 2 hours until the reaction reaches near the theoretical isocyanate value to obtain polyurethane prepolymer.

[0086] B2. Then, the polyurethane prepolymer obtained in B1 is thoroughly mixed with hydroxyl silicone oil and organotin catalyst in a weight ratio of 1:4:0.2, and the mixture is stirred continuously at 70°C for 2 hours until the -NCO characteristic peak disappears, thus obtaining hydroxyl silicone oil modified polyurethane.

[0087] In step B1, the polyether polyol selected is a polyether polyol with a molecular weight of 2000, specifically TDB-2000, and the organotin catalyst is dibutyltin dilaurate.

[0088] Example 2

[0089] A method for preparing a mesh release film includes the following steps:

[0090] S1. First, the functional release agent is coated on one side of the film substrate using an anilox roller coating method under light-protected conditions at a coating speed of 3 m / min. The coating thickness is 15 μm. Then, it is placed in a vacuum oven at 70℃ for pre-baking for 1.5 h. Then, it is cured by ultraviolet radiation for 180 s under nitrogen protection to obtain a single-layer mesh film.

[0091] S2. The single-layer mesh film obtained in S1 is coated with a coating roller. Under light-protected conditions, the functional release agent is coated again on the release layer formed in S1 at a coating speed of 10 m / min, with a coating thickness of 7 μm. Then, it is placed in a vacuum oven at 70°C for pre-baking for 1.5 h, and then cured with ultraviolet radiation for 180 s under nitrogen protection to obtain the mesh release film.

[0092] In this embodiment, the thin film substrate is selected from the thin film substrate prepared in Preparation Example 2.

[0093] In this embodiment, the functional release agent is prepared by fully blending the following raw materials by weight: 80 kg of silicone-modified polyurethane, 50 kg of ethyl acetate, 5.5 kg of photoinitiator 1173, 15 kg of pentaerythritol tetraacrylate, 10 kg of nano silica and 3 kg of acrylate leveling agent.

[0094] The organosilicon-modified polyurethane uses hydroxyl silicone oil-modified polyurethane, and the preparation method of hydroxyl silicone oil-modified polyurethane includes the following steps:

[0095] B1. First, mix the polyether polyol, chain extender and diisocyanate thoroughly in a weight ratio of 1:0.4:0.6, and stir continuously at 65°C for 3 hours until the reaction reaches near the theoretical isocyanate value to obtain polyurethane prepolymer.

[0096] B2. Then, the polyurethane prepolymer obtained in B1 is thoroughly mixed with hydroxyl silicone oil and organotin catalyst in a weight ratio of 1:3:0.1, and the mixture is stirred continuously at 65°C for 3 hours until the -NCO characteristic peak disappears, thus obtaining hydroxyl silicone oil modified polyurethane.

[0097] In step B1, the polyether polyol selected is a polyether polyol with a molecular weight of 2000, specifically TDB-2000, and the organotin catalyst is dibutyltin dilaurate.

[0098] Example 3

[0099] A method for preparing a mesh release film includes the following steps:

[0100] S1. First, the functional release agent is coated on one side of the film substrate using an anilox roller coating method under light-protected conditions at a coating speed of 5 m / min. The coating thickness is 10 μm. Then, it is placed in a vacuum oven at 60℃ for pre-baking for 1.5 h. Then, it is cured for 150 h under nitrogen protection using ultraviolet radiation to obtain a single-layer mesh film.

[0101] S2. The single-layer mesh film obtained in S1 is coated with a coating roller. Under light-protected conditions, the functional release agent is coated again on the release layer formed in S1 at a coating speed of 15 m / min, with a coating thickness of 5 μm. Then, it is placed in a vacuum oven at 60°C for pre-baking for 1.5 h, and then cured with ultraviolet radiation for 150 s under nitrogen protection to obtain the mesh release film.

[0102] In this embodiment, the thin film substrate is selected from the thin film substrate prepared in Preparation Example 2.

[0103] In this embodiment, the functional release agent is prepared by fully blending the following raw materials by weight: 110 kg of silicone-modified polyurethane, 75 kg of ethyl acetate, 6 kg of photoinitiator 1173, 20 kg of pentaerythritol tetraacrylate, 15 kg of nano silica and 5 kg of acrylate leveling agent.

[0104] The organosilicon-modified polyurethane uses hydroxyl silicone oil-modified polyurethane, and the preparation method of hydroxyl silicone oil-modified polyurethane includes the following steps:

[0105] B1. First, mix the polyether polyol, chain extender and diisocyanate thoroughly in a weight ratio of 1:3:0.5, and stir continuously at 70°C for 2 hours until the reaction reaches near the theoretical isocyanate value to obtain polyurethane prepolymer.

[0106] B2. Then, the polyurethane prepolymer obtained in B1 is thoroughly mixed with hydroxyl silicone oil and organotin catalyst in a weight ratio of 1:5:0.1, and the mixture is stirred continuously at 70°C for 2 hours until the -NCO characteristic peak disappears, thus obtaining hydroxyl silicone oil modified polyurethane.

[0107] In step B1, the polyether polyol selected is a polyether polyol with a molecular weight of 2000, specifically TDB-2000, and the organotin catalyst is dibutyltin dilaurate.

[0108] Example 4

[0109] A mesh release film differs from Example 1 in that it uses a different silicone-modified polyurethane.

[0110] In this embodiment, the organosilicon-modified polyurethane is replaced in equal amounts with mercaptosilicone oil-modified polyurethane. The preparation method of the mercaptosilicone oil-modified polyurethane includes the following steps:

[0111] B1. First, mix the polyether polyol, chain extender and diisocyanate thoroughly in a weight ratio of 1:1:0.6, and stir continuously at 70°C for 2 hours until the reaction reaches near the theoretical isocyanate value to obtain polyurethane prepolymer.

[0112] B2. Then, the polyurethane prepolymer obtained in B1 is thoroughly mixed with mercaptosilicone oil and organotin catalyst in a weight ratio of 1:4:0.2, and the mixture is stirred continuously at 70°C for 2 hours until the -NCO characteristic peak disappears, thus obtaining mercaptosilicone oil modified polyurethane.

[0113] In step B1, the polyether polyol selected is a polyether polyol with a molecular weight of 2000, specifically TDB-2000, and the organotin catalyst is dibutyltin dilaurate.

[0114] Example 5

[0115] A mesh release film differs from that of Example 4 in that the silicone-modified polyurethane used is different.

[0116] In this embodiment, the polyether polyol, chain extender and diisocyanate are mixed and reacted in a weight ratio of 1:3:0.6.

[0117] Example 6

[0118] A mesh release film differs from Example 5 in that it uses a different silicone-modified polyurethane.

[0119] In this embodiment, the polyether polyol selected is a polyether polyol with a molecular weight of 4000, specifically TDB-4000.

[0120] Example 7

[0121] A mesh release film differs from Example 5 in that it uses a different silicone-modified polyurethane.

[0122] In this embodiment, the polyether polyol is a mixture of polyether polyol with a molecular weight of 2000 and polyether polyol with a molecular weight of 4000, wherein the weight ratio of the polyether polyol with a molecular weight of 2000 to the polyether polyol with a molecular weight of 4000 is 1:3.

[0123] Example 8

[0124] A mesh release film differs from Example 5 in that it uses a different silicone-modified polyurethane.

[0125] In this embodiment, the polyether polyol is a mixture of polyether polyol with a molecular weight of 2000 and polyether polyol with a molecular weight of 4000, wherein the weight ratio of the polyether polyol with a molecular weight of 2000 to the polyether polyol with a molecular weight of 4000 is 1:5.

[0126] Example 9

[0127] A mesh release film differs from Example 8 in that it uses different nano-silica.

[0128] In this embodiment, nano-silica is replaced in equal amounts with modified nano-silica, wherein the modification step of the modified nano-silica includes:

[0129] C1. First, the nano-silica is vacuum dried. Then, the dried nano-silica is placed in toluene and stirred thoroughly. The temperature is gradually increased to 80°C. Then, KH590 is added, and the temperature is maintained and the reaction is continued to be stirred for 4 hours. The obtained product is filtered under reduced pressure, washed multiple times, and then vacuum dried to finally obtain modified nano-silica.

[0130] Example 10

[0131] A mesh release film differs from Example 9 in that it uses a different photoinitiator.

[0132] In this embodiment, the photoinitiator 1173 undergoes a thiol-capping treatment before addition. The thiol-capping treatment of the photoinitiator 1173 includes the following steps:

[0133] D1. Using ethyl acetate as the reaction solvent, 7.5 kg of isophorone diisocyanate and 0.01 kg of organotin catalyst were added to ethyl acetate and stirred thoroughly. Then, under light-protected conditions, the temperature was gradually increased to 70°C. 5 kg of appropriate amount of photoinitiator 1173 was slowly added dropwise over 30 min, and the reaction was continued in the dark until the theoretical isocyanate value was approached, thus obtaining the isocyanate-modified photoinitiator.

[0134] D2. Add 4 parts of appropriate amount of dimercaprol to the isocyanate-modified photoinitiator obtained in D1, and keep it in the dark at 65°C until the -NCO characteristic peak completely disappears. Finally, remove ethyl acetate by vacuum distillation to obtain thiol-terminated photoinitiator 1173.

[0135] Example 11

[0136] A mesh release film differs from Example 10 in that the nano-silica used and the preparation methods of the photoinitiator are different.

[0137] In this embodiment, the modification steps of the modified nano-silica include:

[0138] C1. First, the nano-silica is vacuum dried. Then, the dried nano-silica is placed in toluene and stirred thoroughly. The temperature is gradually increased to 60°C. Then, KH590 is added, and the temperature is maintained and the reaction is continued to be stirred for 5 hours. The obtained product is filtered under reduced pressure, washed multiple times, and then vacuum dried to finally obtain modified nano-silica.

[0139] In this embodiment, the step of thiol-capping treatment of photoinitiator 1173 includes:

[0140] D1. Using ethyl acetate as the reaction solvent, 5.8 kg of isophorone diisocyanate and 0.00625 kg of organotin catalyst were added to ethyl acetate and stirred thoroughly. Then, under light-protected conditions, the temperature was gradually increased to 65°C, and 5 kg of appropriate amount of photoinitiator 1173 was slowly added dropwise over 30 min. The reaction was continued in the dark until the theoretical isocyanate value was approached, thus obtaining the isocyanate-modified photoinitiator.

[0141] D2. Add 3.5 parts of appropriate amount of dimercaprol to the isocyanate-modified photoinitiator obtained in D1, and keep it in the dark at 60°C until the -NCO characteristic peak completely disappears. Finally, remove ethyl acetate by vacuum distillation to obtain thiol-terminated photoinitiator 1173.

[0142] Comparative Example

[0143] Comparative Example 1

[0144] A mesh release film, which differs from Example 1 in that the film substrate is the same as the film substrate prepared in Preparation Example 3.

[0145] Comparative Example 2

[0146] A mesh release film differs from Example 1 in that the organosilicon-modified polyurethane in the functional release agent is replaced with dimethyl silicone oil in equal amounts.

[0147] Comparative Example 3

[0148] A release film differs from Example 1 in that the preparation steps of the release film are different.

[0149] In this comparative example, a method for preparing a release film includes the following steps:

[0150] S1. Using a coating roller, the functional release agent is coated again onto the release layer formed in S1 at a coating speed of 15 m / min under light-protected conditions, with a coating thickness of 5 μm. Then, it is placed in a vacuum oven at 70°C for pre-baking for 1 hour, and then cured under nitrogen protection by ultraviolet radiation for 180 seconds to obtain the release film.

[0151] Performance test data

[0152] 1. 180° peel force test: The test was conducted according to Chapter 8 of GB / T 25256-2010 Test method for 180° peel force and residual adhesion of optical functional film release film, and the peel force values ​​of each example and comparative example were recorded.

[0153] 2. Residual adhesion rate: The test was conducted according to Chapter 8 of GB / T 25256-2010 Test method for 180° peel force and residual adhesion rate of optical functional film release film, and the residual adhesion rate of each example and comparative example was recorded.

[0154] 3. Adhesion test: The release layer of the mesh release film was subjected to a cross-cut test according to GB / T 9286-2021 Paints and Varnishes, and the adhesion grading results of the release layer were recorded.

[0155] Peel force (mN / 25mm) Residual tack (%) Adhesion rating Example 1 6.23 84％ 2nd Example 2 6.89 87％ 3rd Example 3 6.67 88％ 2nd Example 4 5.92 94％ 1st Example 5 6.17 91％ 1st Example 6 6.86 87％ 0th Example 7 6.42 93％ 1st Example 8 6.59 92％ 0th Example 9 6.70 94％ 0th Example 10 6.95 97％ 0th Example 11 6.88 96％ 0th Comparative Example 1 3.28 46％ 4th Comparative Example 2 4.48 34％ 4th Comparative Example 3 12.13 57％ 3rd

[0156] Based on the data from Example 1 and Comparative Example 1, and combined with Tables 1 and 2, it can be seen that hydrolyzing and re-polymerizing recycled PET significantly improves the peel force, residual adhesion rate, and release layer adhesion of the mesh release film. This is likely because re-polymerization and granulation yields recycled PET with similar degrees of polymerization. The melt molecular weight distribution of the recycled PET is concentrated, and the melt fluctuation is small, which is beneficial for the preparation and processing of film substrates, thus enabling the production of film substrates with uniform and smooth performance. Furthermore, the epoxy phosphate ester backbone added during hydrolysis contains abundant hydroxyl groups, which helps to improve the bonding strength between the film substrate and the functional release agent composed of silicone-modified polyurethane, facilitating the full adhesion of the release layer to the film substrate and reducing the likelihood of interfacial damage.

[0157] According to Example 1 and Comparative Example 2, and in conjunction with the data in Table 1, it can be seen that using silicone-modified polyurethane instead of traditional silicone oil, and then curing it with ultraviolet radiation after coating, can effectively improve the peel force, residual adhesion rate, and adhesion of the release film. This may be because silicone-modified polyurethane contains abundant functional groups, which can react with the abundant hydroxyl groups on the surface of the film substrate during the ultraviolet radiation curing process, thereby improving the adhesion of the functional release agent on the film substrate.

[0158] Based on the data from Example 1 and Comparative Example 3, and in conjunction with Table 1, it can be seen that the release film with a certain thickness and the release film with only a single, thin release layer have a reduced peel force, but a significantly increased residual adhesion rate. This may be because the functional release agent is coated onto the film substrate at a slower speed using an anilox roller, forming a grid of a certain thickness. The raised grid can reduce the contact area between the release film and the object being adhered to a certain extent, resulting in a better release effect, easier peeling from the object, and a higher residual adhesion rate.

[0159] Based on Examples 1 and 4 and the data in Table 1, it can be seen that replacing hydroxyl silicone oil-modified polyurethane with a 1:1 ratio of mercapto-modified polyurethane with mercapto-modified polyurethane improves both the residual adhesion of the mesh release film and the adhesion of the release layer, while decreasing the peel strength. This may be because the CS bond has a lower rotational energy barrier than the CC bond. The lower rotational energy barrier improves the fluidity of the mercapto-modified polyurethane, leading to a decrease in overall viscosity and thus a decrease in peel strength. Furthermore, during UV curing, the mercapto groups can not only react fully with the abundant hydroxyl groups on the film substrate surface, thereby improving the bonding strength between the functional release agent and the film substrate, but also, due to the presence of sulfur atoms after curing, facilitate the formation of hydrogen bonds, which is beneficial for improving the adhesion of the release layer on the film substrate.

[0160] According to Examples 4 and 5 and the data in Table 1, as the amount of chain extender added to the silicone-modified polyurethane increases, the peel force of the release film increases, while the residual adhesion rate decreases. This may be because the chain extender is a multifunctional compound, which provides an opportunity for branching and crosslinking in the synthesis of silicone-modified polyurethane, allowing the prepared silicone-modified polyurethane to form a certain degree of crosslinking structure, thereby increasing the overall viscosity of the silicone-modified polyurethane and improving the surface viscosity of the release layer.

[0161] According to Examples 5-8 and the data in Table 1, as the molecular weight of the single polyether polyol used to prepare silicone-modified polyurethane increases, the peel force of the release film decreases significantly, while the residual adhesion rate increases significantly. However, when TDB-2000 with a molecular weight of 2000 and TDB-4000 with a molecular weight of 4000 are mixed in a certain proportion, the peel force and residual adhesion rate of the release film are improved, and it has a better release effect compared with using a single molecular weight polyether polyol. This may be because when TDB-2000 is used alone, its molecular weight is small and its viscosity is low. Under the same mass conditions, the -NCO content of the synthesized polyurethane prepolymer is higher, and the amount of mercapto silicone oil used for end capping is also increased accordingly. Therefore, more mercapto groups are introduced, so TDB-2000 alone has lower peel strength and higher residual adhesion. However, when TDB-2000 and TDB-4000 are mixed in a certain proportion, TDB-4000 can make up for the insufficient viscosity of TDB-2000, which is beneficial to improving the adhesion of the release layer. Moreover, TDB-2000 can also introduce more mercapto groups, which is beneficial to improving the adhesion with the film substrate, and has a certain synergistic effect.

[0162] According to Examples 8 and 9 and the data in Table 1, the peel strength and residual adhesion of the release film are improved after the addition of modified nano-silica. This may be because the nano-silica is modified with KH590. KH590 introduces thiol groups on the surface of nano-silica, which improves the dispersibility of nano-silica in the functional release agent, thereby reducing the agglomeration of nano-silica in the functional release agent mainly composed of thiol-modified polyurethane. This allows the functional release agent to be uniformly coated on the film substrate. Moreover, during the UV radiation curing process, the thiol groups on the surface of the modified nano-silica may also react with the abundant hydroxyl groups on the surface of the film substrate, which is beneficial to further improve the adhesion of the functional release agent on the film substrate.

[0163] According to the data from Examples 9 and 10 and Table 1, after end-capping the photoinitiator with thiol groups, the peel force and residual adhesion of the release film are slightly improved. This may be because after introducing thiol groups at the end of the photoinitiator, during the UV radiation curing process, the thiol groups at the end of the photoinitiator 1173 may react with the abundant hydroxyl groups on the surface of the film substrate, thereby reducing the residue and migration rate of the cured photoinitiator. Moreover, a large number of thiol groups can also reduce the amount of photoinitiator used in the functional release agent, and have a certain synergistic effect with the photoinitiator, so that the functional release agent can be fully cured on the surface of the film substrate, which is beneficial to further improve the adhesion of the functional release agent on the film substrate.

[0164] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this specific embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method of making a lattice release film, characterized by: A grid release film is prepared, which comprises a film substrate and a release layer coated on the surface of the film substrate, the film substrate is made of hydrolysis treated PET recycled material extrusion, the release layer is formed by multiple coating of functional release agent on the film substrate by an anilox roll and curing by ultraviolet radiation, comprising the following steps: S1, first use anilox roll coating, in the light state, the coating speed is 3-5 m / min, the coating thickness is 10-15 mu m, and then placed in a vacuum oven at 55-70 DEG C for 1-1.5 h, then under the protection of nitrogen, using ultraviolet radiation curing 150-180 s, a single layer grid film is obtained; S2, the single layer grid film obtained in S1 is coated by using a coating roll, in the light state, the coating speed is 10-15 m / min, the coating thickness is 5-7 mu m, then placed in a vacuum oven at 55-70 DEG C for 1-1.5 h, then under the protection of nitrogen, using ultraviolet radiation curing 150-180 s, a grid release film is obtained; The functional release agent comprises the following raw materials by weight: Organic silicon modified polyurethane 80-110 parts; Ethyl acetate 50-75 parts; Photoinitiator 5-6 parts; Pentaerythritol tetraacrylate 15-20 parts; Nano silicon dioxide 10-15 parts; Acrylate leveling agent 3-5 parts; The organic silicon modified polyurethane is prepared by modifying polyurethane with any one of hydroxyl silicone oil and mercapto silicone oil.

2. The method of claim 1, wherein: The organic silicon modified polyurethane is prepared by modifying polyurethane with mercapto silicone oil, and the preparation steps of the mercapto silicone oil modified polyurethane include: B1, first mix polyether polyol, chain extender and diisocyanate, continuously stir at 65-70 DEG C for 2-3 h, and react until the theoretical isocyanate value is reached, to obtain polyurethane prepolymer; B2, then mix the polyurethane prepolymer prepared in B1 with mercapto silicone oil and organic tin catalyst, continuously stir at 65-70 DEG C for 2-3 h, and react until the -C0 characteristic peak disappears, to obtain mercapto silicone oil modified polyurethane.

3. The method of claim 2, wherein: The weight ratio of the polyether polyol, the chain extender and the diisocyanate is 1: (1-3): (0.4-0.6), and the weight ratio of the polyurethane prepolymer, the mercapto silicone oil and the organic tin catalyst is 1: (3-5): (0.1-0.3).

4. The method of claim 2, wherein: The polyether polyol is mixed by 2000 molecular weight polyether polyol and 4000 molecular weight polyether polyol, and the weight ratio of the 2000 molecular weight polyether polyol and the 4000 molecular weight polyether polyol is 1: (3-5).

5. The method of claim 1, wherein: The nano silicon dioxide is modified nano silicon dioxide, and the modification steps include: C1, first vacuum drying of nanosilica, then the dried nanosilica is put into toluene and stirred thoroughly, and gradually heated to 60-80℃, then add KH590, keep the temperature and continue to stir for 4-5h, the resulting product is filtered, washed several times and vacuum dried, finally modified nanosilica is obtained.

6. The method of claim 1, wherein: The photoinitiator is selected from photoinitiator 1173.

7. The method of claim 6, wherein: The photoinitiator 1173 is subjected to mercapto end-capping treatment before being added, and the mercapto end-capping treatment step comprises: D1, using ethyl acetate as the reaction solvent, first add appropriate amount of isophorone diisocyanate and appropriate amount of organic tin catalyst to the ethyl acetate, mix thoroughly, then gradually increase the temperature to 65-70℃ under light shielding conditions, slowly drop appropriate amount of photoinitiator 1173 within 30min, and continue to keep light shielding reaction until the theoretical isocyanate value, to obtain isocyanate modified photoinitiator; D2, add appropriate amount of dimercapto propanol to the isocyanate modified photoinitiator obtained in D1, and keep light shielding at 60-65℃ until the -NCO characteristic peak disappears, finally remove ethyl acetate by vacuum distillation, to obtain mercapto end-capped photoinitiator 1173.

8. The method of claim 1, wherein: The preparation method of the film substrate comprises: A1, sorting the recycled PET plastic bottles, removing the surface impurities of non-PET materials, mixing the PET plastic bottles with a certain amount of water and crushing, then washing and filtering several times to obtain PET chips; A2, put the PET chips obtained in A1 into sodium hydroxide solution, and keep the temperature at 200-250℃ and the pressure at 1.4-2.0MPa for 3-5h, then adjust the solution to neutral with hydrochloric acid solution to obtain PET hydrolysis liquid; A3, mix 30-35 parts of PET hydrolysis liquid, 2-4 parts of n-butyl acetate and 1-2 parts of epoxy phosphate, and keep the temperature at 270-280℃ for 2-3h, then extrude and granulate to obtain PET recycled material; A4, extrude the PET recycled material obtained in A3 to prepare a film substrate.