阅读说明：本技术 用于涂覆的树脂组合物及含其固化产物作为涂层的涂覆膜 (Resin composition for coating and coating film containing cured product thereof as coating layer ) 是由 安祥铉 李东熙 梁毕礼 白成勋 金杭根 安炳准 于 2018-05-31 设计创作，主要内容包括：本发明涉及用于涂覆的树脂组合物以及包含其固化产物作为涂层的涂覆膜。特别地,本发明涉及用于涂覆的树脂组合物以及包含其固化产物作为涂层的涂覆膜,其中,用于涂覆的树脂组合物包含硅氧烷树脂,所述硅氧烷树脂由在其化学结构内包含环氧树脂或丙烯酸的含烷氧基硅烷和二醇的化合物化学键合得到。(The present invention relates to a resin composition for coating and a coating film comprising a cured product thereof as a coating layer. In particular, the present invention relates to a resin composition for coating and a coating film comprising a cured product thereof as a coating layer, wherein the resin composition for coating comprises a silicone resin obtained by chemically bonding an alkoxysilane and diol-containing compound comprising an epoxy resin or an acrylic acid in its chemical structure.)

1. A resin composition for coating, comprising a siloxane resin obtained by chemically bonding a silane compound represented by the following formula 1 and a diol compound represented by the following formula 2:

< formula 1>

R¹ _nSi(OR²)_4-n

Wherein R is¹Is a C1-C3 linear, branched or cyclic alkylene group substituted with an epoxy resin or acrylic acid, R²Is a C1-C8 linear, branched or cyclic alkyl group, n is an integer from 1 to 3,

< formula 2>

HO(CH₂)_nOH

Wherein n is an integer of 1 to 10.

2. The resin composition according to claim 1, wherein the silane compound represented by formula 1 is represented by formula 1: 0.1 to 1: the molar ratio of 1.5 contains the diol compound represented by formula 2.

3. The resin composition according to claim 1, wherein, the silane compound represented by formula 1 includes at least one selected from the group consisting of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropyltripropoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane, and 2- (3, 4-epoxycyclohexyl) ethyltripropoxysilane.

4. The resin composition according to claim 1, wherein the siloxane resin further comprises a silane compound represented by the following formula 3, which is chemically bonded together with the silane compound represented by formula 1 and the diol compound represented by formula 2.

< formula 3>

Si(OR⁴)₄

Wherein R is⁴Is a C1-C4 straight chain or branched chain alkyl group.

5. The resin composition according to claim 4, wherein the silane compound represented by formula 1 is represented by formula 1: the silane compound represented by formula 3 is contained in a molar ratio of 0.01 or more.

6. The resin composition according to claim 1, wherein the silicone resin has a weight average molecular weight of 1000 to 10000 and a molecular weight distribution of 1.2 to 3.4.

7. The resin composition according to claim 1, wherein the resin composition for coating further comprises at least one additive selected from the group consisting of an organic solvent, a photoinitiator, a thermal initiator, an antioxidant, a leveling agent, and a coating aid.

8. A coated film, comprising:

a base film; and

a coating layer which is laminated on at least one surface of the base film and comprises a cured product of the resin composition for coating according to any one of claims 1 to 7 as a coating layer.

9. The coating film according to claim 8, wherein the coating film has a surface hardness of 3H or more in a direction in which the coating layer is formed, in measurement according to ASTM D3363.

10. The coating film according to claim 8, wherein the coating film has a distance of 5mm or less from an edge to a bottom of the film, i.e., a curl, based on a coating thickness of 10 μm.

11. The coated film according to claim 8, wherein the coated film has a radius of curvature of 2.0mm or less as measured using a radial mode of a bending tester JIRBT-620-2 based on a coating thickness of 10 μm.

Technical Field

The present disclosure relates to a resin composition for coating and a coating film comprising a cured product thereof as a coating layer.

Background

Transparent polymer films are widely used as core materials in the field of optical, transparent and flexible displays, especially in the display industry starting to replace glass due to their light weight, ease of processing and their flexibility. However, since the transparent polymer film has disadvantages of low surface hardness and abrasion resistance as compared to glass, a coating technique for improving abrasion resistance of the polymer film becomes an important issue.

Materials for the polymer film generally include organic materials, inorganic materials, and organic-inorganic composite materials. Among them, organic materials have advantages of flexibility and formability due to inherent characteristics of organic substances but have a disadvantage of low surface hardness, while inorganic materials have advantages of high surface hardness and transparency but have disadvantages of poor flexibility and formability. For this reason, organic-inorganic synthetic materials having the advantages of both materials are currently receiving attention, and active research thereof is being conducted. However, it is not currently possible to achieve the advantages of both materials.

In addition, in order to make the surface-coated polymer film suitable for use in optical applications, the most important requirements are that the coating agent should have excellent adhesion to the film and should be free from curling and rainbow phenomenon. Therefore, finding a coating material that can exhibit all of these advantages has become a critical issue in the development of technology.

Several patent documents disclose coating compositions in connection with polymer films. For example, korean patent publication No. 2010-0041992 discloses a high hardness hard-coated film composition comprising an ultraviolet curable urethane acrylate oligomer, and korean patent publication No. 2011-0013891 discloses a vinyl oligosiloxane hybrid composition comprising a metal catalyst. The former case can minimize the curling phenomenon and prevent the rainbow phenomenon due to optical interference. The latter case reports low shrinkage and excellent optical characteristics and heat resistance of the composition having an inorganic network structure.

Meanwhile, international patent publication No. WO 2014-129768 discloses a high-hardness silicone resin composition containing a cyclic epoxy group, a method for producing the same, and an optical film containing a cured product thereof. The patent suggests that the state of the art of hard coatings has increased such that high hardness of 9H can be achieved.

However, the coating material still has limitations in that disadvantages in terms of hardness and permeability are inevitable when advantages of organic materials are emphasized, and disadvantages related to flexibility are not completely overcome when advantages of inorganic materials are emphasized. In particular, organic materials are suitable for surface coating of polymer films due to their flexibility advantages. However, when the surface hardness of the coating is improved by forming a dense network between molecules, the increased shrinkage may cause curling and cracking, which causes peeling of the coating due to deteriorated adhesion. Therefore, in order to use polymer films more widely, a technique capable of preventing deterioration of flexibility of the film due to coating while increasing the surface hardness thereof is urgently required.

Disclosure of Invention

Technical problem

Accordingly, the present invention has been made in view of the above problems, and it is an object of the present disclosure to provide a resin composition for coating, which has a surface hardness of at least 3H and excellent flexibility and wear resistance. It is another object of the present disclosure to provide a coating film comprising a cured product of the resin composition as a coating layer.

Technical scheme

According to a first aspect of the present disclosure for solving the technical problem, there is provided a resin composition for coating, the resin composition comprising a siloxane resin obtained by chemically bonding a silane compound represented by the following formula 1 and a diol compound represented by the following formula 2:

< formula 1>

R¹ _nSi(OR²)_4-n

Wherein R is¹Is a C1-C3 linear, branched or cyclic alkylene group substituted with an epoxy resin or acrylic acid, R²Is a C1-C8 linear, branched or cyclic alkyl group, n is an integer from 1 to 3,

< formula 2>

HO(CH₂)_nOH

Wherein n is an integer of 1 to 10.

May be represented by 1: 0.1 to 1: the molar ratio of 1.5 contains the diol compound represented by formula 2.

The silane compound represented by formula 1 may include at least one selected from the group consisting of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropyltripropoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane, and 2- (3, 4-epoxycyclohexyl) ethyltripropoxysilane.

The siloxane resin may further include a silane compound represented by the following formula 3, which is chemically bonded together with the silane compound represented by formula 1 and the diol compound represented by formula 2.

< formula 3>

Si(OR⁴)₄

Wherein R is⁴Is a C1-C4 straight chain or branched chain alkyl group.

May be represented by 1: the molar ratio of 0.01 or more contains the silane compound represented by formula 3.

The silicone resin may have a weight average molecular weight of 1,000 to 10,000 and a molecular weight distribution of 1.2 to 3.4.

The resin composition for coating may further include at least one additive selected from the group consisting of an organic solvent, a photoinitiator, a thermal initiator, an antioxidant, a leveling agent, and a coating assistant.

According to a second aspect of the present disclosure, there is provided a coating film including a base film and a coating layer laminated on at least one surface of the base film, and the coating layer includes a cured product of the resin composition for coating according to the first aspect of the present invention as the coating layer.

In the measurement according to ASTM D3363, the coating film may have a surface hardness of 3H or more in the direction in which the coating layer is formed.

Based on the coating thickness of 10 μm, the coated film may have a distance (curl) of 5mm or less from the edge to the bottom of the film.

Based on the coating thickness of 10 μm, the coating film may have a radius of curvature of 2.0mm or less as measured in a radial mode using a bending tester (JIRBT-620-2).

Advantageous effects

The present disclosure can maximize flexibility during curing by incorporating a linear diol structure in the polymer bonding structure while ensuring surface hardness and scratch resistance through dense cross-linking of the siloxane network derived from the siloxane molecules.

Detailed Description

In one aspect, the present disclosure relates to a resin composition for coating, the resin composition comprising a siloxane resin obtained by chemically bonding a silane compound represented by the following formula 1 and a diol compound represented by the following formula 2:

< formula 1>

R¹ _nSi(OR²)_4-n

Wherein R is¹Is a C1-C3 linear, branched or cyclic alkylene group substituted by an epoxy resin or acrylic acid, R²Is a C1-C8 linear, branched or cyclic alkyl group, and n is an integer from 1 to 3,

< formula 2>

HO(CH₂)_nOH

Wherein n is an integer of 1 to 10.

The silane compound represented by formula 1 may include at least one selected from the group consisting of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropyltripropoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltriethoxysilane, and 2- (3, 4-epoxycyclohexyl) ethyltripropoxysilane, but is not limited thereto.

However, when a siloxane resin is synthesized using only a silane compound, high surface hardness can be ensured, but since a bonding structure is formed only by dense siloxane crosslinking, there is a limitation in ensuring flexibility. Accordingly, by polymerizing the silicone resin using the silane compound comprising the alkoxysilane represented by formula 1 and the diol compound represented by formula 2, the present disclosure is capable of incorporating a linear diol structure into a polymer chain of the silicone resin, thereby imparting excellent flexibility to a cured product of the resin composition for coating comprising the silicone resin.

More specifically, the diol compound represented by formula 2 according to the present disclosure preferably has a linear structure. The reason for this is that when the linear diol compound has a linear structure, flexibility can be maximized due to free rotation in the molecule.

In the diol compound represented by formula 2, n is an integer of 1 to 10, preferably an integer of 2 to 6. When n is within the above-defined range, the decrease in hardness can be minimized.

The molar ratio of the diol compound represented by formula 2 to the silane compound represented by formula 1 is 1: 0.1 to 1: 1.5, preferably 1: 0.1 to 1: 1.5, more preferably 1: 0.1 to 1: 0.5.

when the molar ratio of the diol compound represented by formula 2 is less than 0.1, there is a limit in achieving bendability due to an insufficient increase in flexibility, and when the molar ratio exceeds 1.5, a decrease in viscosity caused by diol residues makes it difficult to determine a reaction time, which causes problems in a process for preparing a silicone resin.

The silicone resin may further include a silane compound represented by the following formula 3, which is chemically bonded together with the silane compound represented by formula 1 and the diol compound represented by formula 2.

< formula 3>

Si(OR⁴)₄

Wherein R is⁴Is a C1-C4 straight chain or branched chain alkyl group.

The silane compound represented by formula 3 forms a silane Q structure having no alkoxy functional group in Si in a polymer chain of the siloxane resin, so that the resin composition for coating can be cured, thereby providing hardness comparable to that of glass.

With respect to the silane compound represented by formula 1, it is preferable to use 1: the molar ratio of 0.01 or more contains the silane compound represented by formula 3.

When the molar ratio of the silane compound represented by formula 3 is less than 0.01, a silane Q structure having no alkoxy functional group in Si may not be sufficiently formed in a polymer chain in the siloxane resin, and hardness and scratch resistance may be accordingly reduced.

In this regard, when the molar ratio of the silane compound represented by formula 3 is 0.01 or more, a polymerization product having a satisfactory Q structure can be produced, and thus the desired hardness and scratch resistance of the present disclosure can be ensured, and when the silane compound represented by formula 3 is present in an excess amount higher than 0.01 or more, the desired effect is not further improved, and thus, the increased content is not meaningful in terms of improving hardness and scratch resistance.

In the present disclosure, the synthesis of the siloxane resin may be carried out by an alkoxy-diol substitution reaction or by polycondensation. The reaction may be performed at room temperature, but may alternatively be performed while stirring at 50 ℃ to 120 ℃ for 1 to 120 hours. The catalyst for carrying out the substitution reaction (hydrolysis with water) and polycondensation of the alkoxy group with the diol may be: acid catalysts such as hydrochloric acid, acetic acid, hydrogen fluoride, nitric acid, sulfuric acid, or iodic acid; a base catalyst such as ammonia, potassium hydroxide, sodium hydroxide, barium hydroxide or imidazole; and ion exchange resins such as amber (Amberite). These catalysts may be used alone or in combination. The amount of the catalyst may be about 0.0001 parts by weight to about 10 parts by weight based on 100 parts by weight of the silicone resin, but is not particularly limited thereto.

When the substitution reaction and the polycondensation are performed, water or alcohol is generated as a by-product. When this water or alcohol is removed, the reverse reaction can be suppressed and the forward reaction can be performed faster, so that the reaction rate can be controlled by this principle. After the reaction is complete, the by-products can be removed by heating under reduced pressure.

The silicone resin of the present disclosure thus synthesized may have a weight average molecular weight of 1,000 to 10,000 and a polydispersity index (PDI) of 1.2 to 3.4. The molecular weight (Mw) and polydispersity index (PDI) correspond to the weight average molecular weight (Mw) and number average molecular weight (Mn) determined by gel permeation chromatography (GPC, Waters Alliance, model: e2695) for polystyrene. The polymer to be tested was dissolved in tetrahydrofuran at a concentration of 1% and injected into the GPC in an amount of 20 μ l. The mobile phase of GPC was tetrahydrofuran and was supplied at a flow rate of 1.0mL/min, and analyzed at 30 ℃. The columns (columns) used herein were purchased from Waters Styragel HR3, and two columns were connected in series. The detector used herein was an RI detector (Waters Alliance, 2414), and the measurement was performed at 40 ℃. At this time, the molecular weight distribution (PDI) was calculated by dividing the measured weight average molecular weight by the number average molecular weight.

Meanwhile, the resin composition for coating may further include, as another ingredient, at least one additive selected from the group consisting of an organic solvent, a photoinitiator, a thermal initiator, an antioxidant, a leveling agent, and a coating assistant, in addition to the silicone resin. In this case, by controlling the kind and content of the additive used, it is possible to provide a resin composition for coating suitable for various applications. In the present disclosure, it is preferable to provide a resin composition for coating capable of improving hardness, abrasion resistance, flexibility and curling resistance.

For example, the initiator according to the present disclosure is a photopolymerization initiator such as an organic metal salt and a photopolymerization initiator such as an amine and imidazole. In this case, the amount of the initiator added is preferably about 0.5 to 5 parts by weight based on 100 parts by weight of the total amount of the silicone resin. When the content of the initiator is less than 0.5 parts by weight, the curing time of the coating layer required to obtain sufficient hardness is extended, and thus efficiency is reduced. When the content of the initiator is more than 5 parts by weight, the yellowness of the coating layer may increase, thereby making it difficult to obtain a transparent coating layer.

In addition, the organic solvent may include at least one selected from the group consisting of ketones (e.g., acetone, methyl ethyl ketone, methyl butyl ketone, and cyclohexanone), cellosolves (e.g., methyl cellosolve and butyl cellosolve), ethers (e.g., diethyl ether and dioxane), alcohols (e.g., isobutanol, isopropanol, butanol, and methanol), halogenated hydrocarbons (e.g., dichloromethane, chloroform, and trichloroethylene), and hydrocarbons (e.g., n-hexane, benzene, and toluene). In particular, since the viscosity of the silicone resin can be controlled by controlling the amount of the added organic solvent, the workability can be further improved, or the thickness of the coating film can be controlled.

Further, the present disclosure may provide a cured product having high hardness obtained by using a method such as coating, casting, or molding and then performing photopolymerization or thermal polymerization. Specifically, the present disclosure relates to a coating film which includes a base film and a coating layer laminated on at least one surface of the base film, and which includes a cured product of a resin composition for coating as the coating layer. The coating film may have a surface hardness of at least 3H in a direction in which the coating layer is formed, in measurement according to ASTM D3363. Based on the coating thickness of 10 μm, the coated film may have a distance (curl) of 5mm or less from the edge to the bottom of the film. Based on the coating thickness of 10 μm, the coating film may have a radius of curvature of 2.0mm or less as measured in a radial mode using a bending tester (JIRBT-620-2). This means that the resin composition has hardness and quite excellent curling properties and flexibility.

In the present disclosure, when the resin composition for coating is polymerized, the amount of light suitable for photopolymerization may be not less than 50mJ/cm²And not more than 20,000mJ/cm²And the heat treatment may be performed at a temperature of not less than 40 c and not more than about 300 c in order to obtain a uniform surface before photopolymerization. In addition, the temperature suitable for the thermal polymerization is not lower than 40 ℃ and not higher than 300 ℃, but is not limited thereto.