Release agent and preparation method thereof, release coating and fluorine-containing release film

Abstract

The invention discloses a release agent and a preparation method thereof, a release coating and a fluorine-containing release film, and relates to the technical field of release films, and the preparation method of the release agent comprises the following steps: mixing polyvinyl alcohol and a polar solvent to obtain a first solution; an acid catalyst and a reaction monomer are added into the first solution, a reaction solution is obtained, and the reaction monomer comprises an acyl monomer and / or an isocyanate monomer; adjusting the reaction liquid to be neutral, and carrying out solid-liquid separation to obtain a white fibrous solid; and purifying and drying the white fibrous solid to obtain the release agent. The release property of the release film is improved.

Description

Technical Field

[0001] The present application relates to the technical field of release films, and in particular to a release agent and a preparation method thereof, a release coating, and a fluorine-containing release film. Background Art

[0002] In the field of display technology, polarizer release film plays a vital role and is an indispensable part of the display panel manufacturing process. As a key protective layer before the lamination process, the main function of the polarizer release film is to ensure that the pressure-sensitive adhesive layer of the polarizer is protected from external contamination and damage, thereby effectively preventing the generation of bubbles during the lamination process and providing a solid foundation for the clarity and stability of the display panel. Polyester film, especially polyethylene terephthalate (PET) and other types, is widely used as a material for polarizer release film due to its excellent comprehensive performance.

[0003] However, polyester film also has certain limitations when used as a release film for polarizers. Specifically, polyester film has strong adhesion to resins and adhesives, which leads to problems such as uneven film peeling and residues during demolding. These problems not only reduce the manufacturing efficiency of display panels, but may also have a negative impact on the quality of the final product.

[0004] The above contents are only used to assist in understanding the technical solution of the present application and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The main purpose of the present application is to provide a release agent and a preparation method thereof, a release coating, and a fluorine-containing release film, aiming to improve the release properties of the release film.

[0006] To achieve the above object, the present invention provides a release agent, wherein the release agent has a structure as shown in formula (1):

[0007]

[0008] Wherein, R1 is a straight chain, branched chain alkane, aromatic hydrocarbon or alicyclic hydrocarbon containing fluorine atoms, and R2 and R3 are selected from: OCOC b H 2b+1 (6≤b≤30) and CONHC b H 2b+1 Any one of (6≤b≤30);

[0009] The release agent satisfies 200≤2x+(2y+z)+r≤3000, 5%≤Px≤60%, 5%≤Pr≤90%, 5%≤P(y+z)≤60%, x represents the number of repeating structural units of the first component, r represents the number of repeating structural units of the second component, (y+z) represents the number of repeating structural units of the third component, P represents the ratio of the repeating structural units, and z≥0.

[0010] In addition, to achieve the above-mentioned purpose, the present application also provides a method for preparing a release agent, which is used to prepare the release agent as described above, and comprises the following steps:

[0011] Mixing polyvinyl alcohol and a polar solvent to obtain a first solution;

[0012] Adding an acidic catalyst and a reaction monomer to the first solution to obtain a reaction solution, wherein the reaction monomer comprises: an acyl monomer and / or an isocyanate monomer;

[0013] The reaction solution is adjusted to neutrality, and solid-liquid separation is performed to obtain a white fibrous solid;

[0014] The white fibrous solid is purified and dried to obtain a release agent.

[0015] In one embodiment, the polar solvent includes: at least one of N-methylpyrrolidone, dimethyl sulfoxide and water;

[0016] and / or, the mass ratio between the polyvinyl alcohol and the polar solvent is 1:(6-40);

[0017] And / or, the hydroxyl content of the polyvinyl alcohol is 10 to 90%;

[0018] And / or, the molar ratio between the reactive monomer and the hydroxyl group in the polyvinyl alcohol is (0.1-0.9):1;

[0019] and / or, the molar ratio between the polyvinyl alcohol and the acidic catalyst is (4-16):1;

[0020] And / or, the acidic catalyst includes at least one of hydrochloric acid, nitric acid, sulfuric acid and oxalic acid.

[0021] In one embodiment, the isocyanate monomer comprises at least one of the compounds represented by formula (2):

[0022]

[0023] Wherein, R4 is selected from a straight-chain alkane, branched alkane, aromatic hydrocarbon or alicyclic hydrocarbon group containing at least one fluorine atom, and the total number of atoms of R4 is an integer of 3 to 30.

[0024] In one embodiment, the acyl monomer includes: a first monomer, wherein the first monomer includes at least one of the compounds represented by formula (3):

[0025]

[0026] Wherein, X is selected from any one of H, F, Cl, Br and I, R5 is selected from a straight-chain alkane, branched alkane, aromatic hydrocarbon or alicyclic hydrocarbon group containing at least one fluorine atom, and the total number of C atoms is an integer of 3 to 30.

[0027] In one embodiment, the acyl monomer further comprises: a second monomer, wherein the second monomer comprises at least one of the compounds represented by formula (4):

[0028]

[0029] Wherein, X is selected from any one of H, F, Cl, Br and I, R6 is selected from a straight-chain alkane, a branched alkane, an aromatic hydrocarbon or an alicyclic hydrocarbon group, and the total number of C atoms is an integer of 3 to 30.

[0030] In addition, to achieve the above-mentioned purpose, an embodiment of the present application also proposes a release coating, which includes: a release agent, a cross-linking agent, a water-dispersible resin and a water-soluble resin, wherein the release agent is the release agent as described above.

[0031] In one embodiment, the release coating comprises: 5 to 90 wt. % of a release agent, 3 to 90 wt. % of a cross-linking agent, 3 to 80 wt. % of a water-dispersible resin, and 1 to 60 wt. % of a water-soluble resin.

[0032] In one embodiment, the cross-linking agent is an isocyanate cross-linking agent, including at least one of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-diisocyanatohexane, lysine diisocyanate, 1,3-bis(isocyanatomethyl)-cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, norbornene diisocyanate, 4-toluene diisocyanate, 2,6-toluene diisocyanate and 4,4'-diphenylmethane diisocyanate;

[0033] And / or, the water-dispersible resin comprises: a copolyester resin having an aromatic ring structure;

[0034] And / or, the water-soluble resin includes: polyvinyl alcohol.

[0035] In addition, to achieve the above objectives, an embodiment of the present application further proposes a fluorine-containing release film, which comprises: a polymer film layer and a release coating provided on at least one side of the polymer film layer, wherein the release coating is the release coating as described above.

[0036] One or more technical solutions proposed in the embodiments of the present application have at least the following technical effects: a release agent is provided, which is composed of a polyvinyl alcohol structure grafted with a long-chain alkane molecule. Due to the presence of the polyvinyl alcohol structure, on the one hand, it is ensured that the release coating prepared by applying the release agent has excellent transparency and meets the requirements of the release film for transparency. On the other hand, it also provides an ideal site for the grafting of long-chain alkane molecules, so that the release agent can form a uniform lubricating layer on the base film (such as a polyester film). The formation of this lubricating layer helps to reduce the contact area between the final product (such as a polarizer release film) and the pressure-sensitive adhesive layer protecting the polarizer, thereby reducing the adhesion between them and significantly improving the demoulding performance. In addition, a fluorine-containing group is also introduced into the release agent of the embodiment of the present application, thereby effectively solving the problem that when preparing the release agent, due to the influence of steric hindrance, the long-chain alkane molecules are difficult to fully approach the active sites of polyvinyl alcohol, resulting in a limited grafting rate. The fluorine-containing group has an extremely low surface energy, and therefore, it can further reduce the surface energy of the release agent, thereby significantly improving the demoulding performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a flow chart of a method for preparing a release agent according to an embodiment of the present application.

[0038] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0040] Hereinafter, the embodiments of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0041] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0042] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0043] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0044] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0045] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0046] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0047] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and understandable, the technical solution of the present application is further described below in conjunction with the accompanying drawings and embodiments. However, the present application is not limited to the listed embodiments, and should also include any other known changes within the scope of the rights claimed in the present application.

[0048] The term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present application. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0049] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0050] In conventional technology, polyester film has insufficient demoulding properties for various resins and adhesives, which leads to problems such as demoulding difficulty, uneven film peeling, and residue in practical applications. This, to a certain extent, limits the widespread application of polyester film in the field of polarizer release films. In order to improve the demoulding performance, conventional methods often coat the surface of the polyester film with a silicon-containing release coating, but such substances can easily contaminate the polarizer and affect the display effect. At the same time, since polar solvents may remain on the surface of the release coating or penetrate into the interior of the polarizer during the volatilization process, causing contamination to the polarizer, the coating liquid that forms the release coating should also not contain polar solvents.

[0051] The embodiment of the present application provides a solution, specifically, a release agent is provided, which is composed of a polyvinyl alcohol structure grafted with a long-chain alkane molecule. Due to the presence of the polyvinyl alcohol structure, on the one hand, it is ensured that the release coating prepared by applying the release agent has excellent transparency and meets the requirements of the release film for transparency. On the other hand, it also provides an ideal site for the grafting of long-chain alkane molecules, so that the release agent can form a uniform lubricating layer on the base film (such as a polyester film). The formation of this lubricating layer helps to reduce the contact area between the final product (such as a polarizer release film) and the pressure-sensitive adhesive layer protecting the polarizer, thereby reducing the adhesion between them and significantly improving the demoulding performance. In addition, a fluorine-containing group is also introduced into the release agent of the embodiment of the present application, thereby effectively solving the problem that when preparing the release agent, due to the influence of steric hindrance, the long-chain alkane molecules are difficult to fully approach the active sites of polyvinyl alcohol, resulting in a limited grafting rate. The fluorine-containing group has an extremely low surface energy, and therefore, the surface energy of the release agent can be further reduced, thereby significantly improving the demoulding performance.

[0052] The first aspect of the embodiment of the present application provides a release agent, the release agent having a structure shown in formula (1):

[0053]

[0054] Wherein, R1 is a straight chain, branched chain alkane, aromatic hydrocarbon or alicyclic hydrocarbon containing fluorine atoms, and R2 and R3 are selected from: OCOC b H 2b+1 (6≤b≤30) and CONHC b H 2b+1 Any one of (6≤b≤30);

[0055] The release agent satisfies 200≤2x+(2y+z)+r≤3000, 5%≤Px≤60%, 5%≤Pr≤90%, 5%≤P(y+z)≤60%, x represents the number of repeating structural units of the first component, r represents the number of repeating structural units of the second component, (y+z) represents the number of repeating structural units of the third component, P represents the ratio of the repeating structural units, and z≥0.

[0056] It should be understood that by adjusting the length and degree of substitution of long-chain alkanes, their molecular structure can be precisely regulated, thereby affecting their demolding effect in release coatings and fluorine-containing release films. If the long-chain alkane molecules are too short or the degree of substitution is low, the surface energy reduction effect of the release agent is poor, which will reduce the demolding efficiency. On the contrary, if the long-chain alkane molecules are too long, the grafting efficiency of the long-chain alkane molecules and the substrate may be reduced, resulting in a low degree of substitution, and it is difficult to meet the requirements of the release agent. The embodiments of the present application further take into account that the long-chain alkane molecules are large in volume and may be difficult to fully contact the active sites of polyvinyl alcohol, which may limit the progress of the grafting reaction. In order to solve this problem, the embodiments of the present application introduce fluorine-containing groups into the release agent. The surface energy of these groups is extremely low, which can further reduce the surface energy of the release agent, thereby improving the demolding performance.

[0057] The second aspect of the present application provides a method for preparing a release agent, referring to Figure 1 The method for preparing a release agent comprises the following steps:

[0058] Step S10, mixing polyvinyl alcohol and a polar solvent to obtain a first solution;

[0059] In a feasible embodiment, polyvinyl alcohol and a polar solvent are uniformly mixed to prepare a colorless and transparent first solution.

[0060] In one feasible embodiment, the mass ratio between polyvinyl alcohol and the polar solvent is 1:(6-40); for example, the mass ratio between polyvinyl alcohol and the polar solvent is 1:6, 1:8, 1:10, 1:12, 1:14, 1:16, 1:18, 1:20, 1:22, 1:24, 1:26, 1:28, 1:30, 1:32, 1:34, 1:36, 1:38, 1:40, etc.

[0061] Preferably, the mass ratio between polyvinyl alcohol and polar solvent is 1:(6-30).

[0062] Exemplarily, the polar solvent includes at least one of N-methylpyrrolidone, dimethyl sulfoxide and water.

[0063] In one feasible embodiment, the hydroxyl content of polyvinyl alcohol is 10-90%; for example, the hydroxyl content of polyvinyl alcohol is 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, etc. Among them, the hydroxyl content is 100% when all hydroxyl groups are free hydroxyl groups. If the hydroxyl content is too high, the release agent may contain more hydroxyl residues, affecting the release force. If the hydroxyl content is too low, there will be fewer hydroxyl groups that can undergo substitution reactions, making it difficult to prepare a release agent polymer with performance that meets the requirements.

[0064] Preferably, the hydroxyl content of the polyvinyl alcohol is 10 to 88%.

[0065] Step S20, adding an acidic catalyst and a reaction monomer to the first solution to obtain a reaction solution, wherein the reaction monomer includes: an acyl monomer and / or an isocyanate monomer;

[0066] In a feasible embodiment, an acidic catalyst and a reaction monomer are added to the first solution in sequence, wherein the reaction monomer includes: an acyl monomer and / or an isocyanate monomer; and then after reacting at a certain temperature for a period of time, a white solid is precipitated to obtain a solid-liquid mixed reaction solution. Among them, the isocyanate group (-NCO) in the isocyanate monomer has a strong reactivity and can react with the hydroxyl group in the polyvinyl alcohol, thereby grafting a long-chain alkane molecule in the polyvinyl alcohol structure. The acyl monomer liquid can provide a functional group that can react with the hydroxyl group of the polyvinyl alcohol and undergo an amidation reaction with it, thereby grafting a long-chain alkane molecule in the polyvinyl alcohol structure. The acidic catalyst can transfer hydrogen ions to the hydroxyl group of the polyvinyl alcohol to form a protonated hydroxyl group, which makes the protonated hydroxyl group a better electrophilic reagent and more easily attacks the carbonyl group (C=O) in the compound shown in formula (3) and / or (4), so that the hydroxyl group and the carbonyl group undergo nucleophilic addition to form an intermediate containing a carbon-carbon double bond, thereby promoting the forward progress of the reaction.

[0067] Exemplarily, the acyl monomer includes: an aldehyde monomer and / or an acylated monomer.

[0068] In one feasible embodiment, the molar ratio between the reactive monomer and the hydroxyl group in the polyvinyl alcohol is (0.1-0.9): 1. For example, the molar ratio between the reactive monomer and the hydroxyl group in the polyvinyl alcohol is 0.1: 1, 0.15: 1, 0.2: 1, 0.25: 1, 0.3: 1, 0.35: 1, 0.4: 1, 0.45: 1, 0.5: 1, 0.55: 1, 0.6: 1, 0.65: 1, 0.7: 1, 0.75: 1, 0.8: 1, 0.85: 1, 0.9: 1, etc. By controlling the molar ratio between the reactive monomer and the hydroxyl group in the polyvinyl alcohol, the length and degree of substitution of the long-chain alkane in the prepared release agent polymer can be regulated.

[0069] In one possible embodiment, the molar ratio between polyvinyl alcohol and the acidic catalyst is (4-16): 1. For example, the molar ratio between polyvinyl alcohol and the acidic catalyst is 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, etc.

[0070] In one possible embodiment, the acidic catalyst includes at least one of hydrochloric acid, nitric acid, sulfuric acid and oxalic acid.

[0071] In one possible embodiment, the isocyanate monomer comprises at least one of the compounds represented by formula (2):

[0072]

[0073] Wherein, R4 is selected from a straight-chain alkane, branched alkane, aromatic hydrocarbon or alicyclic hydrocarbon group containing at least one fluorine atom, and the total number of atoms of R4 is an integer of 3 to 30.

[0074] In one feasible embodiment, the acyl monomer includes: a first monomer, the first monomer includes at least one of the compounds represented by formula (3):

[0075]

[0076] Wherein, X is selected from any one of H, F, Cl, Br and I, R5 is selected from a straight-chain alkane, branched alkane, aromatic hydrocarbon or alicyclic hydrocarbon group containing at least one fluorine atom, and the total number of C atoms is an integer of 3 to 30.

[0077] Exemplarily, when X is selected from H, the first monomer is an aldehyde monomer; when X is selected from F, Cl, Br or I, the first monomer is an acylation monomer.

[0078] In one feasible embodiment, the acyl monomer includes: a first monomer and a second monomer, and the second monomer includes at least one of the compounds represented by formula (4):

[0079]

[0080] Wherein, X is selected from any one of H, F, Cl, Br and I, R6 is selected from a straight-chain alkane, a branched alkane, an aromatic hydrocarbon or an alicyclic hydrocarbon group, and the total number of C atoms is an integer of 3 to 30.

[0081] In a feasible embodiment, the reaction solution is obtained by reaction at a reaction temperature of 5 to 120° C. and a reaction time of 0.5 to 48 hours. For example, the reaction solution is obtained by reaction at a reaction temperature of 5° C., 10° C., 20° C., 30° C., 40° C., 50° C., 60° C., 70° C., 80° C., 90° C., 100° C., 110° C., 120° C., etc. For example, the reaction solution is obtained by reaction at a reaction time of 0.5h, 1h, 5h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 46h, 47h, 48h, etc.

[0082] Step S30, adjusting the reaction solution to neutrality, and performing solid-liquid separation to obtain a white fibrous solid;

[0083] In one feasible embodiment, an alkaline solution (e.g., sodium hydroxide solution) is added dropwise to the reaction liquid to neutralize it to neutrality (pH=7) to obtain a heterogeneous liquid. At the same time, since the reaction product has a cross-linked structure, a fibrous solid is formed, and a white fibrous solid is obtained by solid-liquid separation.

[0084] Step S40, purifying and drying the white fibrous solid to obtain a release agent.

[0085] In one possible embodiment, the release agent polymer is prepared by removing impurities and water from the reaction product (ie, white fibrous solid) through multiple purification and drying steps.

[0086] In this embodiment, a release agent polymer consisting of a polyvinyl alcohol structure grafted with a long-chain alkane molecule and a fluorine-containing group is prepared. Since the release agent contains a polyvinyl alcohol structure, the release coating prepared by applying the release agent has excellent transparency, which greatly satisfies the transparency requirements of the fluorine-containing release film further prepared by applying the release coating. Furthermore, the polyvinyl alcohol structure has a hydroxyl site, so long-chain alkane molecules can be grafted. This enables the release agent to be closely arranged on the surface of the base film (e.g., polyester film) based on the unique extended chain configuration of the long-chain alkane molecules in practical application to form a dense lubricating layer; thereby helping to reduce the actual contact area between the final product (e.g., fluorine-containing release film) and the pressure-sensitive adhesive layer protecting the polarizer, reduce the adhesion between them, and improve demoulding. In addition, a fluorine-containing group is also introduced into the release agent of the embodiment of the present application, thereby effectively solving the problem that when preparing the release agent, due to the influence of steric hindrance, the long-chain alkane molecules are difficult to fully approach the active sites of polyvinyl alcohol, resulting in a limited grafting rate. The fluorine-containing group has an extremely low surface energy and can therefore further reduce the surface energy of the release agent, thereby significantly improving the release performance.

[0087] The third aspect of the embodiment of the present application provides a release coating, comprising: a release agent, a cross-linking agent, a water-dispersible resin and a water-soluble resin, wherein the release agent has a structure shown in formula (1):

[0088]

[0089] Wherein, R1 is a straight chain, branched chain alkane, aromatic hydrocarbon or alicyclic hydrocarbon containing fluorine atoms, and R2 and R3 are selected from: OCOC b H 2b+1 (6≤b≤30) and CONHC b H 2b+1 Any one of (6≤b≤30);

[0090] The release agent satisfies 200≤2x+(2y+z)+r≤3000, 5%≤Px≤60%, 5%≤Pr≤90%, 5%≤P(y+z)≤60%, x represents the number of repeating structural units of the first component, r represents the number of repeating structural units of the second component, (y+z) represents the number of repeating structural units of the third component, P represents the ratio of the repeating structural units, and z≥0.

[0091] In one feasible embodiment, the release coating comprises: 5 to 90 wt. % of a release agent, 3 to 90 wt. % of a cross-linking agent, 3 to 80 wt. % of a water-dispersible resin, and 1 to 60 wt. % of a water-soluble resin.

[0092] Exemplarily, the release agent content of the release coating is: 5wt.%, 10wt.%, 15wt.%, 20wt.%, 25wt.%, 30wt.%, 35wt.%, 40wt.%, 45wt.%, 50wt.%, 55wt.%, 60wt.%, 65wt.%, 70wt.%, 75wt.%, 80wt.%, 85wt.%, 90wt.%, etc. The release agent contains a polyvinyl alcohol structure, so that the release coating has excellent transparency, which greatly meets the transparency requirements of the fluorine-containing release film further prepared by applying the release coating. Furthermore, the polyvinyl alcohol structure of the release agent is grafted with long-chain alkane molecules, so that the release coating can be closely arranged on the surface of the base film (for example, polyester film) to form a dense lubricating layer, and helps to reduce the actual contact area between the final product (for example, the fluorine-containing release film) and the pressure-sensitive adhesive layer protecting the polarizer, reduce the adhesion between them, and improve the demolding property. At the same time, fluorine-containing groups are introduced, which have extremely low surface energy, and therefore can further reduce the surface energy of the release agent, thereby significantly improving the demoulding performance.

[0093] Preferably, the release agent content of the release coating is 20 to 80 wt.%.

[0094] Exemplarily, the crosslinking agent content of the release coating is: 3wt.%, 5wt.%, 10wt.%, 15wt.%, 20wt.%, 25wt.%, 30wt.%, 35wt.%, 40wt.%, 45wt.%, 50wt.%, 55wt.%, 60wt.%, 65wt.%, 70wt.%, 75wt.%, 80wt.%, 85wt.%, 90wt.%, etc. The crosslinking agent can promote the crosslinking reaction between the resin molecules in the release coating, thereby improving the strength, heat resistance and chemical resistance of the coating. Through the crosslinking reaction, chemical bonds are formed between the resin molecules, making the coating more stable.

[0095] Preferably, the crosslinking agent content of the release coating is 20 to 75 wt.%.

[0096] Exemplarily, the water-dispersible resin content of the release coating is: 3wt.%, 5wt.%, 10wt.%, 15wt.%, 20wt.%, 25wt.%, 30wt.%, 35wt.%, 40wt.%, 45wt.%, 50wt.%, 55wt.%, 60wt.%, 65wt.%, 70wt.%, 75wt.%, 80wt.%, etc. The water-dispersible resin can form a stable dispersion system in water, which helps to evenly coat the coating liquid of the release coating on the substrate. The resin molecules cross-link with each other during the drying process of the coating to form a film with certain strength and toughness.

[0097] Preferably, the water-dispersible resin content of the release coating is 5 to 60 wt.%.

[0098] Exemplarily, the water-soluble resin content of the release coating is 1wt.%, 5wt.%, 10wt.%, 15wt.%, 20wt.%, 25wt.%, 30wt.%, 35wt.%, 40wt.%, 45wt.%, 50wt.%, 55wt.%, 60wt.%, etc. The water-soluble resin can form a uniform film with good transparency and glossiness during the drying process of the coating. The water-soluble resin can also enhance the adhesion, flexibility and impact resistance of the coating and improve the overall performance of the coating.

[0099] Preferably, the water-soluble resin content of the release coating is 5 to 50 wt.%.

[0100] In one feasible embodiment, the crosslinking agent is an isocyanate crosslinking agent, including at least one of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-diisocyanatohexane, lysine diisocyanate, 1,3-bis(isocyanatomethyl)-cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, norbornene diisocyanate, 4-toluene diisocyanate, 2,6-toluene diisocyanate and 4,4'-diphenylmethane diisocyanate. The addition of the isocyanate crosslinking agent can improve the adhesion between the release coating and the base film.

[0101] In one possible embodiment, the water-dispersible resin includes: a copolyester resin having an aromatic ring structure.

[0102] For example, the water-dispersible resin can be a resin obtained by condensation polymerization of an aromatic dicarboxylic acid and a polyol, or a polycarboxylic acid and an aromatic diol. The addition of the water-dispersible polyester can improve the leveling property of the coating liquid of the release coating on the base film, and can also improve the adhesion performance of the release coating and the base film.

[0103] Exemplarily, the water-dispersible resin includes at least one of polyethylene terephthalate, polybutylene terephthalate, polyethylene isophthalate, unsaturated polyester resin, aromatic polyester polyol, and polyarylate.

[0104] In one feasible embodiment, the water-soluble resin includes: polyvinyl alcohol.

[0105] For example, the degree of polymerization of polyvinyl alcohol may be 200 to 3000, and the degree of saponification may be 50 to 99 mol%.

[0106] Preferably, the saponification degree of the polyvinyl alcohol is 70 to 90 mol%.

[0107] In one feasible embodiment, a method for preparing a release coating is provided, comprising: dispersing a release agent in deionized water to prepare an aqueous dispersion of the release agent; mixing a water-soluble resin, a cross-linking agent, a water-dispersible resin, a release agent and water to form a coating liquid, wherein an aqueous dispersion of the water-dispersible resin, a water-soluble resin solution and an aqueous dispersion of the release agent can be prepared first, and then the components are mixed; applying the coating liquid to the surface of a base film, and heat-treating it at 40 to 240° C. to obtain a release coating.

[0108] A fourth aspect of an embodiment of the present application provides a fluorine-containing release film, comprising: a polymer film layer and a release coating disposed on at least one side of the polymer film layer.

[0109] The release coating comprises: a release agent, a cross-linking agent, a water-dispersible resin and a water-soluble resin, wherein the release agent has a structure shown in formula (1):

[0110]

[0111] Wherein, R1 is a straight chain, branched chain alkane, aromatic hydrocarbon or alicyclic hydrocarbon containing fluorine atoms, and R2 and R3 are selected from: OCOC b H 2b+1 (6≤b≤30) and CONHC b H 2b+1 Any one of (6≤b≤30);

[0112] The release agent satisfies 200≤2x+(2y+z)+r≤3000, 5%≤Px≤60%, 5%≤Pr≤90%, 5%≤P(y+z)≤60%, x represents the number of repeating structural units of the first component, r represents the number of repeating structural units of the second component, (y+z) represents the number of repeating structural units of the third component, P represents the ratio of the repeating structural units, and z≥0.

[0113] In one feasible embodiment, a method for preparing a fluorine-containing release film is provided, comprising:

[0114] Step A10, dispersing the release agent in deionized water to prepare a release agent aqueous dispersion;

[0115] Step A20, mixing a water-soluble resin, a cross-linking agent, a water-dispersible resin, a release agent and water to form a coating liquid, wherein an aqueous dispersion of a water-dispersible resin, a water-soluble resin solution and an aqueous dispersion of a release agent may be prepared first, and then the components are mixed;

[0116] Step A30, coating the coating liquid on the surface of the polymer film (ie, the base film), and heat treating the film at 40 to 240° C. to obtain a fluorine-containing release film.

[0117] Exemplarily, the polymer film may be a polyester film.

[0118] In order to enable the details and operations of the above embodiments of the present application to be clearly understood by those skilled in the art, and to significantly demonstrate the improved performance of the embodiments of the present application, the above technical solutions are illustrated by means of multiple embodiments below.

[0119] Example 1

[0120] (1) mixing polyvinyl alcohol having a hydroxyl content of 88% and water to obtain a first solution, wherein the mass ratio between the polyvinyl alcohol and the water is 1:10;

[0121] (2) Add hydrochloric acid (acidic catalyst) to the first solution 、 Octadecanyl chloride (second monomer) and p-trifluoromethylbenzaldehyde (first monomer) are reacted at 10° C. for 2.5 h, and then at 60° C. for 2 h to obtain a reaction solution, wherein the molar ratio between the hydroxyl group in the polyvinyl alcohol and the hydrochloric acid is 8:1, and the molar ratio between the hydroxyl group in the polyvinyl alcohol, octadecyl chloride and p-trifluoromethylbenzaldehyde is 1:0.15:0.1;

[0122] (3) adding 15 wt.% NaOH solution to the reaction solution to neutralize the reaction solution to pH = 7, and a white fibrous solid precipitated;

[0123] (4) washing and purifying the white fibrous solid by ethanol and deionized water multiple times and drying to obtain a release agent;

[0124] (5) Polyvinyl alcohol (water-soluble resin), tetramethylene diisocyanate (crosslinking agent), polyethylene terephthalate (water-dispersible resin) 、 The release agent and water are mixed to form a coating liquid with a solid content of 2 wt.%;

[0125] (6) The coating liquid is coated on a base film (PET), and then heat-treated at 150° C. for 2 min to obtain a polarizer release film, wherein the mass ratio of the release agent, the water-dispersible resin, the cross-linking agent and the polyvinyl alcohol in the release coating after drying is 4:2:3:1.

[0126] Example 2

[0127] The experimental steps are the same as those in Example 1, except that:

[0128] In step (2), the molar ratio of hydroxyl group, octadecyl chloride and p-trifluoromethylbenzaldehyde in polyvinyl alcohol is 1:0.25:0.1.

[0129] Example 3

[0130] The experimental steps are the same as those in Example 1, except that:

[0131] In step (2), the molar ratio of hydroxyl group, octadecyl chloride and p-trifluoromethylbenzaldehyde in polyvinyl alcohol is 1:0.3:0.1.

[0132] Example 4

[0133] The experimental steps are the same as those in Example 1, except that:

[0134] In step (2), the molar ratio of hydroxyl group, octadecyl chloride and p-trifluoromethylbenzaldehyde in polyvinyl alcohol is 1:0.3:0.15.

[0135] Example 5

[0136] The experimental steps are the same as those in Example 1, except that:

[0137] In step (2), the molar ratio of hydroxyl group, octadecyl chloride and p-trifluoromethylbenzaldehyde in polyvinyl alcohol is 1.6:1.6:0.1:1.

[0138] Example 6

[0139] The experimental steps are the same as those in Example 1, except that:

[0140] In step (2), the molar ratio of hydroxyl group, octadecyl chloride and p-trifluoromethylbenzaldehyde in polyvinyl alcohol is 1:0.3:0.2.

[0141] Example 7

[0142] The experimental steps are the same as those in Example 1, except that:

[0143] In step (2), the molar ratio of hydroxyl group, octadecyl chloride and p-trifluoromethylbenzaldehyde in polyvinyl alcohol is 1:0.4:0.1.

[0144] Example 8

[0145] In step (2), the molar ratio of hydroxyl group, octadecyl chloride and p-trifluoromethylbenzaldehyde in polyvinyl alcohol is 1:0.5:0.1.

[0146] Example 9

[0147] The experimental steps are the same as those in Example 1, except that:

[0148] In step (2), the second monomer is dodecyl chloride.

[0149] Example 10

[0150] The experimental steps are the same as those in Example 1, except that:

[0151] In step (2), the second monomer is tetradecanoyl chloride.

[0152] Embodiment 11

[0153] The experimental steps are the same as those in Example 1, except that:

[0154] In step (2), the second monomer is hexadecyl acyl chloride.

[0155] Example 12

[0156] The experimental steps are the same as those in Example 1, except that:

[0157] In step (2), the second monomer is eicosyl chloride.

[0158] Comparative Example 1

[0159] The experimental steps are the same as those in Example 1, except that:

[0160] In step (2), p-trifluoromethylbenzaldehyde is not added, and the molar ratio between the hydroxyl group and the octadecyl chloride in the polyvinyl alcohol is 1:0.15.

[0161] The fluorine-containing release films of Examples 1 to 10 and Comparative Example 1 were subjected to performance tests, including:

[0162] (1) Transmittance and haze test:

[0163] The transmittance and haze of the film after the second heat treatment were tested using a transmittance haze meter.

[0164] (2) Release film peeling force test:

[0165] A release film sample with a width of 25 mm and a length of 200 mm was cut, and the adhesive tape was pressed back and forth on the coating surface with a 2 kg rubber roller, and the peeling force was measured after being placed at room temperature for 1 hour; wherein, the peeling force was tested with a universal testing machine, the peeling angle was 180°, and the tensile rate was 300 mm / min.

[0166] The experimental results are shown in Table 1 below:

[0167] Table 1:

[0168] Test Group Light transmittance (%) Haze(%) Peel force (N / mm) Example 1 89.8 1.3 0.145 Example 2 89.7 1.2 0.105 Example 3 89.5 1.1 0.069 Example 4 89.6 0.9 0.048 Example 5 89.9 1.0 0.042 Example 6 89.7 1.1 0.39 Example 7 89.8 1.3 0.57 Example 8 89.6 1.4 0.51 Example 9 89.1 1.5 0.132 Example 10 89.2 1.4 0.121 Embodiment 11 89.1 1.3 0.110 Example 12 89.2 1.2 0.96 Comparative Example 1 89.6 1.5 0.164

[0169] According to the above test results, the fluorine-containing release films prepared in Examples 1 to 12 of the present application all have good light transmittance, low haze and high clarity. Compared with the fluorine-containing release film in Comparative Example 1, the fluorine-containing release film prepared in the examples of the present application has better demoulding properties.

[0170] The above are only preferred embodiments of the present application, and do not limit the scope of the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of patent protection of the present application.

Claims

1. A release agent, characterized in that The release agent has a structure shown in formula (1): Wherein, R1 is a straight chain, branched chain alkane, aromatic hydrocarbon or alicyclic hydrocarbon containing fluorine atoms, and R2 and R3 are selected from: OCOC b H 2b+1 (6≤b≤30) and CONHC b H 2b+1 Any one of (6≤b≤30); The release agent satisfies 200≤2x+(2y+z)+r≤3000, 5%≤Px≤60%, 5%≤Pr≤90%, 5%≤P(y+z)≤60%, x represents the number of repeating structural units of the first component, r represents the number of repeating structural units of the second component, (y+z) represents the number of repeating structural units of the third component, P represents the ratio of the repeating structural units, and z≥0.

2. A method for preparing a release agent, characterized in that: The method for preparing a release agent is applied to prepare the release agent as claimed in claim 1, comprising the following steps: Mixing polyvinyl alcohol and a polar solvent to obtain a first solution; Adding an acidic catalyst and a reaction monomer to the first solution to obtain a reaction solution, wherein the reaction monomer comprises: an acyl monomer and / or an isocyanate monomer; The reaction solution is adjusted to neutrality, and solid-liquid separation is performed to obtain a white fibrous solid; The white fibrous solid is purified and dried to obtain a release agent.

3. The method for preparing a release agent as claimed in claim 2, characterized in that ,, the polar solvent includes: at least one of N-methylpyrrolidone, dimethyl sulfoxide and water; and / or, the mass ratio between the polyvinyl alcohol and the polar solvent is 1:(6-40); And / or, the hydroxyl content of the polyvinyl alcohol is 10 to 90%; And / or, the molar ratio between the reactive monomer and the hydroxyl group in the polyvinyl alcohol is (0.1-0.9):1; and / or, the molar ratio between the polyvinyl alcohol and the acidic catalyst is (4-16):1; And / or, the acidic catalyst includes at least one of hydrochloric acid, nitric acid, sulfuric acid and oxalic acid.

4. The method for preparing a release agent according to claim 2, characterized in that ,, the isocyanate monomer includes at least one of the compounds represented by formula (2): Wherein, R4 is selected from a straight-chain alkane, branched alkane, aromatic hydrocarbon or alicyclic hydrocarbon group containing at least one fluorine atom, and the total number of atoms of R4 is an integer of 3 to 30.

5. The method for preparing a release agent according to claim 2, characterized in that ,, the acyl monomer includes: a first monomer, the first monomer includes at least one of the compounds represented by formula (3): Wherein, X is selected from any one of H, H, F, Cl, Br and I, R5 is selected from a straight-chain alkane, branched alkane, aromatic hydrocarbon or alicyclic hydrocarbon group containing at least one fluorine atom, and the total number of C atoms is an integer of 3 to 30.

6. The method for preparing a release agent according to claim 5, characterized in that ,, the acyl monomer further comprises: a second monomer, the second monomer comprising at least one of the compounds represented by formula (4): Wherein, X is selected from any one of H, F, Cl, Br and I, R6 is selected from a straight-chain alkane, a branched alkane, an aromatic hydrocarbon or an alicyclic hydrocarbon group, and the total number of C atoms is an integer of 3 to 30.

7. A release coating, characterized in that: The release coating comprises: a release agent, a cross-linking agent, a water-dispersible resin and a water-soluble resin, wherein the release agent is the release agent according to claim 1, or a release agent prepared by the release agent preparation method according to any one of claims 2 to 6.

8. The release coating according to claim 7, characterized in that: The release coating comprises: 5 to 90 wt.% of a release agent, 3 to 90 wt.% of a cross-linking agent, 3 to 80 wt.% of a water-dispersible resin and 1 to 60 wt.% of a water-soluble resin.

9. The release coating according to claim 7, characterized in that: The cross-linking agent is an isocyanate cross-linking agent, including at least one of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-diisocyanatohexane, lysine diisocyanate, 1,3-bis(isocyanatomethyl)-cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, norbornene diisocyanate, 4-toluene diisocyanate, 2,6-toluene diisocyanate and 4,4'-diphenylmethane diisocyanate; And / or, the water-dispersible resin comprises: a copolyester resin having an aromatic ring structure; And / or, the water-soluble resin includes: polyvinyl alcohol.

10. A fluorine-containing release film, characterized in that: The fluorine-containing release film comprises: a polymer film layer and a release coating provided on at least one side of the polymer film layer, wherein the release coating is the release coating according to any one of claims 7 to 9.

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