Photocurable coating composition and coating film using same

Abstract

A photocurable coating composition according to the present invention exhibits excellent adhesion to a display panel even with a low adhesive strength (5 kgf / inch or less), and is easily peelable, and thus can be used as an easily removable protective film. The photocurable coating composition according to the present invention may be applied by curing only necessary portions of the composition after applying same, and thus reduces costs and is economical. Moreover, additional waste such as a release film or a protective film is not generated, and thus the composition is environmentally friendly.

Description

Photocurable coating composition and coating film using the same

[0001] The present invention relates to a photocurable coating composition and a coating film using the same. More specifically, the present invention relates to a photocurable coating composition comprising (A) 1 to 50 wt% of a photocurable bifunctional urethane (meth)acrylate oligomer, (B) 70 to 90 wt% of a photocurable (meth)acrylate monomer, (C) 0.1 to 10 wt% of a photopolymerization initiator, (D) 0.001 to 5 wt% of an antioxidant, and (E) 0.1 to 5 wt% of a surface additive, and a coating film for a display device using the same.

[0002]

[0003] Display-related devices, such as display modules, polarizers, TVs, laptops, and computer monitors, are typically handled with a functional protective film attached to the screen to prevent contamination and surface damage caused by atmospheric dust and foreign substances during transport, storage, or processing. In particular, maintaining a clean, scratch-free screen is crucial for displays, from the manufacturing and packaging stages through to delivery to the end consumer. Therefore, polyester protective films are commonly used to protect the display surface from the external environment and maintain operational performance. While PET protective films offer excellent transparency, tensile strength, impact resistance, and solvent resistance, they are also extremely hard and can cause surface damage to substrates such as display screens. Furthermore, the high cost of PET leads to significant raw material costs. Furthermore, because they are fully coated onto the substrate, materials are wasted, even in areas where coating is not necessary. Furthermore, before applying a PET protective film, the release film and protective film covering the top and bottom of the film must be removed, generating unnecessary waste.

[0004]

[0005] Prior literature

[0006] 1. Prior patent: Republic of Korea Publication No. 10-2010-0069661

[0007]

[0008] Accordingly, the inventors of the present invention have made great efforts to improve the problems of conventional protective films, and as a result, they synthesized a photocurable bifunctional urethane (meth)acrylate oligomer, and adjusted the content of the photocurable (meth)acrylate monomer, the photopolymerization initiator, and the additives to produce a low-viscosity resin composition of 20 cps or less (25°C), and have confirmed that the resin composition has excellent adhesion to the display panel even with low adhesion (5 kgf / inch or less), has a modulus of 1 GPa, secures film properties, has easy peeling properties, and does not deteriorate in a high-temperature environment, thereby completing the present invention.

[0009]

[0010] However, the problems that the present invention seeks to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0011]

[0012] According to the first embodiment, the present invention

[0013] (A) 1 to 50 wt% of photocurable bifunctional urethane (meth)acrylate oligomer,

[0014] (B) 70 to 90 wt% of photocurable (meth)acrylate monomer,

[0015] (C) 0.1 to 10 wt% of photopolymerization initiator,

[0016] (D) 0.001 to 5 wt% of antioxidant, and

[0017] (E) It is intended to provide a photocurable coating composition comprising 0.1 to 5 wt% of a surface additive.

[0018] In the present invention, the photocurable bifunctional urethane (meth)acrylate oligomer (A) may have a weight average molecular weight of 1,000 to 2,500 g / mol.

[0019] In the present invention, the (A) photocurable bifunctional urethane (meth)acrylate oligomer can be synthesized from a composition comprising (i) a polyolefin polyol or a polyether polyol, (ii) an isocyanate component, (iii) a urethane reaction catalyst, and (iv) a polymerization inhibitor. The polyol can include a copolymer of polybutadiene polyol, polypropylene glycol, polyethylene glycol, ethylene oxide, and propylene oxide. The isocyanate component is C1 to C 20 The urethane reaction catalyst may include at least one selected from the group consisting of copper naphthlenate, cobalt naphthinate, zinc naphthate, n-butyltinlaurate, tristhylamine, and 2-methyltriethylenediamide. The polymerization inhibitor may include at least one selected from the group consisting of butylated hydroxytoluene (BHT), hydroquinone, hydroquinone monomethyl ether, para-benzoquinone, and phenothiazine.

[0020] In the present invention, the (B) photocurable (meth)acrylate monomer may include 65 to 75 wt% of (B-1) monofunctional (meth)acrylate and 5 to 15 wt% of (B-2) polyfunctional (meth)acrylate based on the total weight of the photocurable coating composition.

[0021] In the present invention, the (B-1) monofunctional (meth)acrylate may be isobornyl acrylate, and the (B-2) polyfunctional (meth)acrylate may be dipropylene glycol diacrylate.

[0022] In the present invention, the photopolymerization initiator (C) may include at least one selected from the group consisting of benzoin-based, hydroxy ketone-based, amino ketone-based, and phosphine oxide-based photoinitiators.

[0023] In the present invention, the photopolymerization initiator (C) may be phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0024] In the present invention, the (D) antioxidant may include at least one selected from the group consisting of a phenol-based antioxidant, a sulfur-based antioxidant, and a phosphorus-based antioxidant.

[0025] The above (D) antioxidant may be thiodiethylene bis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate].

[0026] In the present invention, the (E) surface additive may include at least one selected from the group consisting of a polyacrylate-based surfactant, a silicone-containing surfactant, and an acrylic-based surfactant.

[0027] In the present invention, the photocurable coating composition may further include at least one additive selected from the group consisting of a silane coupling agent, an adhesion promoter, a thermal polymerization inhibitor, a saturated fatty acid having 8 or more carbon atoms, an antistatic agent, a catalyst, a resin component other than a urethane resin, an inorganic filler, an organic filler, a metal powder, a pigment, a softener, a plasticizer, an anti-aging agent, a conductive agent, an antioxidant, a UV absorber, a light stabilizer, a surface lubricant, a leveling agent, a corrosion inhibitor, a heat-resistant stabilizer, a polymerization inhibitor, a lubricant, and a solvent.

[0028] In the present invention, the viscosity of the photocurable coating composition may be 10 to 20 cps (25°C).

[0029]

[0030] According to the second embodiment, the present invention

[0031] It is intended to provide a coating film formed using a photocurable coating composition according to the first embodiment.

[0032] In the present invention, the coating film can be attached to one or more display devices selected from the group consisting of a plasma display, a field emission display, an organic EL display, an inorganic EL display, and electronic paper.

[0033] In the present invention, the peeling force of the coating film may be 1 to 7 gf / inch.

[0034] In the present invention, the surface resistance of the coating film is 10 12 10 inland 15 It could be Ω / sq.

[0035]

[0036] The photocurable coating composition according to the present invention not only exhibits excellent adhesion to a display panel even with low adhesion (5 kgf / inch or less), but also has a modulus of approximately 1 GPa, ensuring film properties and enabling easy peeling, and can be used as a protective film. The photocurable coating composition according to the present invention is economical because it can be coated by curing only the necessary areas after coating, thereby reducing costs, and is environmentally friendly because it does not generate additional waste such as release films and protective films.

[0037]

[0038] Meanwhile, the scope of the present invention is not limited by the effects described above.

[0039]

[0040] Hereinafter, a photocurable coating composition and a coating film using the same according to specific embodiments of the invention will be described in detail. However, this is presented as one example of the invention, and the scope of the invention is not limited thereby. It will be apparent to those skilled in the art that various modifications to the embodiments are possible within the scope of the invention. Unless otherwise specified, throughout this specification, "include" or "contains" refers to including a certain component (or component) without any particular limitation, and cannot be interpreted as excluding the addition of other components (or components).

[0041] As used herein, the term “(meth)acrylic” means “acrylic” and / or “methacrylic”, and “(meth)acrylate” means “acrylate” and / or “methacrylate”.

[0042] The term "weight average molecular weight" used herein is measured by a conventional method known in the art, and can be measured, for example, by a GPC (gel permeation chromatography) method.

[0043]

[0044] 1. Photocurable coating composition

[0045] The present invention provides a photocurable coating composition comprising (A) a photocurable bifunctional urethane (meth)acrylate oligomer, (B) a photocurable (meth)acrylate monomer, (C) a photopolymerization initiator, (D) an antioxidant, and (E) a surface additive.

[0046] In the photocurable coating composition according to the present invention, the viscosity of the photocurable coating composition may be 20 cps or less (25°C), preferably 10 to 20 cps (25°C), and more preferably 12 to 18 cps (25°C).

[0047] Hereinafter, the composition of the photocurable coating composition according to the present invention will be specifically examined as follows.

[0048]

[0049] A. Photocurable bifunctional urethane (meth)acrylate oligomer

[0050] The photocurable bifunctional urethane (meth)acrylate oligomer according to the present invention serves to improve the film properties of a coating film prepared from a photocurable coating composition.

[0051] The above photocurable bifunctional urethane (meth)acrylate oligomer may have a weight average molecular weight of 1,000 to 2,500 g / mol, preferably 1,500 to 2,000 g / mol. If the weight average molecular weight of the above photocurable bifunctional urethane (meth)acrylate oligomer is less than 1,000 g / mol, it may be difficult to secure film properties, and if the weight average molecular weight of the above photocurable bifunctional urethane (meth)acrylate oligomer exceeds 2,500 g / mol, it may be difficult to secure discharge properties and problems of poor peelability may occur.

[0052] The above photocurable bifunctional urethane (meth)acrylate oligomer may be included in an amount of 1 to 50 wt%, preferably 10 to 30 wt%, based on the total weight of the photocurable coating composition of the present invention. If the content of the bifunctional urethane (meth)acrylate oligomer is less than 1 wt%, it is difficult to secure film properties, and if the content of the bifunctional urethane (meth)acrylate oligomer exceeds 50 wt%, it is difficult to secure ejectability in coating equipment due to an increase in viscosity, and problems such as a long tack time may occur.

[0053] The photocurable bifunctional urethane (meth)acrylate oligomer used in the present invention can be synthesized from a composition comprising (i) a polyol component, (ii) an isocyanate component, (iii) a urethane reaction catalyst, and (iv) a polymerization inhibitor.

[0054] (i) polyol component

[0055] The above polyol component includes at least one selected from the group consisting of polyester polyol, polyether polyol, polyolefin polyol, polycarbonate polyol, polycarprolactone polyol, tetrahydrofuran propyleneoxide ring opening copolymer, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexandiol, neopentyl glycol, and 1,4-cyclohexane dimethanol, and bisphenol-A type diols. However, the present invention is not limited thereto. Preferably, the polyol component may include a polyolefin polyol or a polyether polyol, for example, the polyol component may include a polybutadiene polyol, a polypropylene glycol, a polyethylene glycol, a copolymer of ethylene oxide and propylene oxide. More preferably, the polyol component may be a polypropylene glycol, or a copolymer of ethylene oxide and propylene oxide.

[0056] (ii) Isocyanate component

[0057] The above isocyanate component is C1 to C 20It may include at least one selected from the group consisting of alkyl isocyanate, 2-isocyanatoethyl methacrylate, allyl isocyanate and 3-isopropenyl-α,α-dimethylbenzyl isocyanate, but is not limited thereto. The above C1 to C 20 Examples of alkyl isocyanates may include, but are not limited to, 2-ethylhexyl isocyanate, hexyl isocyanate, heptyl isocyanate, octyl isocyanate, decyl isocyanate, pentyl isocyanate, dodecyl isocyanate, tetradecyl isocyanate, or octadecyl isocyanate. Preferably, the isocyanate may be 2-isocyanatoethyl methacrylate.

[0058] (iii) Urethane reaction catalyst

[0059] The above urethane reaction catalyst may include at least one selected from the group consisting of copper naphthlenate, cobalt naphthinate, zinc naphthate, n-butyltin laurate, tristhylamine, and 2-methyltriethylenediamide, but is not limited thereto. Preferably, the urethane reaction catalyst may be dibutyltin laurate.

[0060] (iv) polymerization inhibitor

[0061] The polymerization inhibitor may include, but is not limited to, one or more selected from the group consisting of butylated hydroxytoluene (BHT), hydroquinone, hydroquinone monomethyl ether, para-benzoquinone, and phenothiazine. Preferably, the polymerization inhibitor may be butylated hydroxytoluene.

[0062]

[0063] B. Photocurable (meth)acrylate monomer

[0064] The photocurable (meth)acrylate monomer according to the present invention serves to control the viscosity of the photocurable coating composition and to improve the hardness of the manufactured coating film. The photocurable (meth)acrylate monomer can be classified into a monofunctional (meth)acrylate monomer (1 monomer) and a polyfunctional (meth)acrylate monomer (2 or more monomers) depending on the number of polymerizable functional groups, for example, (meth)acrylate groups, contained in one molecule.

[0065] The photocurable (meth)acrylate monomer used in the present invention includes a combination of (B-1) monofunctional (meth)acrylate and (B-2) polyfunctional (meth)acrylate.

[0066] The photocurable (meth)acrylate monomer may be included in an amount of 70 to 90 wt% based on the total weight of the photocurable coating composition of the present invention, and preferably, the photocurable (meth)acrylate monomer may include 65 to 75 wt% of a monofunctional (meth)acrylate monomer and 5 to 15 wt% of a polyfunctional (meth)acrylate monomer based on the total weight of the photocurable coating composition of the present invention. When the content of the photocurable (meth)acrylate monomer is within the above range, it is easy to control viscosity and dissolve solids (initiator) to secure dischargeability, and it can have excellent hardness and film properties as a protective film.

[0067] (B-1) Monofunctional (meth)acrylate

[0068] Examples of the above monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, isoamyl (meth)acrylate, isomyristyl (meth)acrylate, n-lauryl (meth)acrylate, n-stearyl (meth)acrylate, isostearyl (meth)acrylate, n-butoxyethyl (meth)acrylate, butoxydiethylene glycol (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, Butoxyethyl (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, glycidyl (meth)acrylate, methoxyethylene glycol modified (meth)acrylate, ethoxyethylene glycol modified (meth)acrylate, propoxyethylene glycol modified (meth)acrylate, methoxypropylene glycol modified (meth)acrylate, Ethoxypropylene glycol modified (meth)acrylate, propoxypropylene glycol modified (meth)acrylate, tetrahydrofuryl (meth)acrylate, acryloyl morpholine, phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxyethylene glycol modified (meth)acrylate, phenoxypropylene glycol modified (meth)acrylate, hydroxyphenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, hydroxyphenoxyethylene glycol modified (meth)acrylate, hydroxyphenoxypropylene glycol modified (meth)acrylate, alkylphenol ethylene glycol modified (meth)acrylate, alkylphenol propylene glycol modified (meth)acrylate,It may include at least one selected from the group consisting of ethoxylated o-phenylphenol (meth)acrylate and isobornyl (meth)acrylate, but is not limited thereto. Preferably, the monofunctional (meth)acrylate may be isobornyl acrylate.

[0069] (B-2) Multifunctional (meth)acrylate

[0070] The above multifunctional (meth)acrylates include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyolefin glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, ethoxylated polypropylene glycol di(meth)acrylate, 2-hydroxy-1,3-dimethacryloxypropane, dioxane glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, glycerin di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol Di(meth)acrylate, neopentyl glycol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, butylethylpropanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol F di(meth)acrylate, ethoxylated glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, It may include at least one selected from the group consisting of pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and dipentaerythritol polyacrylate, but is not limited thereto. Preferably, the polyfunctional (meth)acrylate may be dipropylene glycol diacrylate.

[0071] The above photocurable (meth)acrylate monomer may include a monofunctional (meth)acrylate monomer and a polyfunctional (meth)acrylate monomer in a weight ratio of 13 to 15: 1 to 3. When the above photocurable (meth)acrylate monomer includes a monofunctional photocurable (meth)acrylate monomer and a polyfunctional photocurable (meth)acrylate monomer in the above weight ratio, there is an effect of simultaneously satisfying the viscosity of the photocurable coating composition and the hardness of the manufactured coating film.

[0072]

[0073] C. Photopolymerization initiator

[0074]

[0075] *The photopolymerization initiator according to the present invention serves to initiate a curing reaction in a photocurable coating composition.

[0076] The photopolymerization initiator may be included in an amount of 0.1 to 10 wt%, preferably 0.1 to 5 wt%, based on the total weight of the photocurable coating composition of the present invention. If the content of the photopolymerization initiator is less than 0.1 wt%, it is difficult to secure a curing rate, and if the content of the photopolymerization initiator exceeds 10 wt%, the YI (Yellow Index) increases significantly and migration and byproducts may occur after curing due to unreacted initiator.

[0077] The above photopolymerization initiator may be selected from the group consisting of benzoin-based, hydroxy ketone-based, amino ketone-based, and phosphine oxide-based photoinitiators, but is not limited thereto. For example, the photopolymerization initiator is selected from the group consisting of benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylamino acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, Dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-t-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, acetophenone dimethylketal, p-dimethylamino benzoic acid ester, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide or phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide can be used. Preferably, the photopolymerization initiator can be phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0078] The above photopolymerization initiator may be used together with a photosensitizer to improve the photoinitiation efficiency, and the photosensitizer may include, but is not limited to, a thioxanthone or benzophenone derivative compound.

[0079]

[0080] D. Antioxidants

[0081] The antioxidant according to the present invention serves to improve the reliability (thermal stability) after curing of the photocurable coating composition.

[0082] The above antioxidant may be included in an amount of 0.001 to 5 wt%, preferably 0.02 to 0.5 wt%, based on the total weight of the photocurable coating composition of the present invention. If the content of the antioxidant is less than 0.001 wt%, it is difficult to ensure storage stability at high temperatures, and if the content of the antioxidant exceeds 5 wt%, a curing mechanism may occur.

[0083] The above antioxidant may be selected from the group consisting of, but is not limited to, one or more phenol-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants. Examples of the above phenolic antioxidants include bis-(3,3-bis-(4'-hydroxy-3'-tetrabutylphenol)butanoic acid-glycol ester, 2,6-di-tert-butyl-4-methylphenol, 4,4'-thiobis(2-tert-butyl-5-methylphenol), tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyphenyl)propionate methane, 1,2-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl) hydrazine, thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, Isotridecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N,N'-hexamethylene bis(3,5-di-t-butyl-4-hydroxyhydrocinnamamide), 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoic acid, branched alkyl ester having 7 to 9 carbon atoms, 2,2'-ethylenebis(4,6-di-tert-butylphenol), 1,3,5-triethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl) benzene, 4,6-bis(octylthiomethyl)-o-cresol, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, 2,2'-methylenebis(4-methyl-6-t-butylphenol), triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, 2,5-di-tert-amyl-hydroquinone, hexamethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tris-(3,5-di-tert-butylhydroxybenzyl) isocyanurate, or 4,4'-butylidenebis(6-tert-butyl-3-methylphenol).Examples of the above-mentioned phosphorus antioxidants may include, but are not limited to, triethylphosphite, triisopropylphosphite, triisodecylphosphite, tridodecylphosphite, phenylisodecylphosphite, diphenylisodecylphosphite, triphenylphosphite, phenyl-bis(4-nonylphenyl)phosphate, tris-(4-octylphenyl)phosphate, tris-[4-(1-phenylethyl)phenyl]-phosphite, tris(2,4-di-tert-butylphenyl)phosphate, tris(2,4-di-tert-butylphenyl)phosphate, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, poly(dipropylene glycol) phenylphosphate, diphenyl isodecyl phosphate, or 2-ethylhexyl diphenyl phosphate. Examples of the above sulfur-based antioxidants may include, but are not limited to, pentaerythrityl tetrakis(3-laurylthiopropionate), dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, or ditridecyl thiodipropionate. Preferably, the antioxidant may be thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate].

[0084]

[0085] E. Surface additives

[0086] The surface additive according to the present invention serves to improve the leveling and application properties of the photocurable coating composition and to improve the peelability from the substrate after curing.

[0087] The above surface additive may be included in an amount of 0.1 to 5 wt%, preferably 0.1 to 1 wt%, based on the total weight of the photocurable coating composition of the present invention. If the content of the surface additive is less than 0.1 wt%, it is difficult to secure the spreadability, application property, and initial peelability of the photocurable coating composition, and if the content of the surface additive exceeds 5 wt%, stains due to unreacted substances after curing may occur, and it may be difficult to secure reliability.

[0088] The above surface additive may be selected from the group consisting of a polyacrylate surfactant, a silicone-containing surfactant, and an acrylic surfactant, but is not limited thereto. The above surface additive may be selected from the group consisting of a low molecular weight acidic polyester, an unsaturated polyamine amide salt, a high molecular weight alkylolaminoamide, a high molecular weight block copolymer solution, an alkyl ammonium salt of a high molecular weight copolymer, an acrylate copolymer, a hydroxyl functional group carboxylic acid ester, a polyether-modified polydimethylsiloxane, an acrylic-modified polymethylalkylsiloxane, a polyether-modified polydimethylsiloxane, and a combination thereof. For example, the surface additive may be BYK-306, BYK-310, BYK-320, BYK-331, BYK-333, BYK-342, BYK-350, BYK-354, BYK-355, BYK-356, BYK-358N, BYK-359, BYK-361N, BYK-381, BYK-370, BYK-371, BYK-378, BYK-388, BYK-392, BYK-394, BYK-399, BYK-3440, BYK-3441, BYK-UV3500, BYK-UV3530, BYK-UV3570 of BYK, or Rad of TEGO. 2100, Rad 2011, Glide 100, Glide 410, Glide 450, or Fluorad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430 of Sumitomo 3M, or Zonyl FS-300, FSN, FSN-100, FSO of DuPont and combinations thereof may be used, and preferably, BYK-UV3500, BYK-UV3530, BYK-UV3570 of BYK, which is a UV reactive additive with low migration after curing, may be used alone or in combination of two or more, but is not limited thereto. Preferably, the surface additive may be polydimethylsiloxane.

[0089]

[0090]

[0091] *F. Other additives

[0092] The photocurable coating composition according to the present invention may further include, in addition to the antioxidant and surface additive, a silane coupling agent, an adhesion promoter, a thermal polymerization inhibitor, or a saturated fatty acid having 8 or more carbon atoms as an additive.

[0093] Examples of the above silane coupling agent include, but are not limited to, one or more selected from the group consisting of vinyltrimethoxy silane, vinyltriethoxy silane, trimethoxysilanyl(meth)acrylate, and vinyltriethoxysilanyl(meth)acrylate.

[0094] Examples of the above polymerization inhibitor include, but are not limited to, one or more selected from the group consisting of hydroquinone, methyl ether hydroquinone, and 2,6-di-tert-butyl-4-methyl phenol.

[0095]

[0096] *In addition, the photocurable coating composition according to the present invention may further include, but is not limited to, one or more additives from the group consisting of an antistatic agent, a catalyst, a resin component other than a urethane resin, an inorganic filler, an organic filler, a metal powder, a pigment, a softener, a plasticizer, an anti-aging agent, a conductive agent, an antioxidant, a UV absorber, a light stabilizer, a surface lubricant, a leveling agent, an anti-corrosion agent, a heat-resistant stabilizer, a polymerization inhibitor, a lubricant, and a solvent, within a range that does not impair the effects of the present invention.

[0097]

[0098] 2. Coating film

[0099] The present invention seeks to provide a coating film formed using the photocurable coating composition described above.

[0100] In the coating film according to the present invention, the surface tension of the coating film may be 20 to 30 dyne / cm2 (25°C), preferably 23 to 26 dyne / cm2 (25°C).

[0101] In the photocurable coating composition according to the present invention, the YI (yellow index) of the coating film may be 0.1 to 1.0.

[0102] In the coating film according to the present invention, the adhesion of the coating film may be 5 kgf / inch or less, preferably 1.0 to 5 kgf / inch, and more preferably 1.0 to 3.0 kgf / inch. If the adhesion is less than k1 gf / inch, there is a problem that the coating film, etc., peels off too easily, making it unsuitable for the purpose of protecting the adhesive layer. If the adhesion exceeds 7 kgf / inch, there may be a problem that the adhesive layer is damaged when peeled.

[0103] In the coating film according to the present invention, the surface resistance of the coating film is 10 12 10 inland 15 Ω / sq, preferably 10 12 10 inland 15 It could be Ω / sq.

[0104] In the coating film according to the present invention, the coating film can be attached to a display device. The display device can be selected from the group consisting of a plasma display, a field emission display, an organic EL display, an inorganic EL display, and electronic paper, but is not limited thereto.

[0105]

[0106] Below, various examples are presented to aid understanding of the invention. These examples are provided solely to facilitate understanding of the invention and are not intended to limit the scope of protection of the invention.

[0107]

[0108] <Manufacturing Example>

[0109] The photocurable bifunctional urethane (meth)acrylate oligomer used in the photocurable coating composition according to the present invention was prepared using the diol backbone and isocyanate shown in Table 1 below.

[0110] [Table 1]

[0111]

[0112]

[0113] Manufacturing Example 1. Photocurable oligomer containing polybutadiene

[0114] In a 500 mL jacketed glass reactor equipped with a stirrer, a thermometer, and 92 parts by weight of polybutadiene diol (Nippo Soda, GI-1000) and 0.02 parts by weight of butylated hydroxytoluene (Sigma Aldrich) as a polymerization inhibitor were added, the reactor temperature was raised to 30°C, and the mixture was stirred for 0.5 hours. 8 parts by weight of 2-isocyanatoethyl acrylate (Karenz, AOI) was added to the reactor, the reactor temperature was raised to 60°C, and the mixture was reacted for 2 hours. The reactant was measured by infrared spectroscopy (IR) to confirm that the isocyanate groups had disappeared, and the reaction was terminated, thereby obtaining a bifunctional urethane compound having an ethylenically unsaturated double bond and a weight-average molecular weight of 1,500 g / mol.

[0115]

[0116] Manufacturing Example 2. Photocurable oligomer containing polypropylene glycol

[0117] In a 500 mL jacketed glass reactor equipped with a stirrer, a thermometer, and 88 parts by weight of polypropylene glycol (KPX Chemical, PP-1000) and 0.02 parts by weight of butylated hydroxytoluene (Sigma Aldrich) as a polymerization inhibitor were added, the reactor temperature was raised to 30°C, and the mixture was stirred for 0.5 hours. 12 parts by weight of 2-isocyanatoethyl acrylate (Karenz, AOI) was added to the reactor, the reactor temperature was raised to 60°C, and the mixture was reacted for 2 hours. The reactant was measured by infrared spectroscopy (IR) to confirm that the isocyanate groups had disappeared, and the reaction was terminated to obtain a bifunctional urethane compound having an ethylenically unsaturated double bond and a weight average molecular weight of 1,500 g / mol.

[0118]

[0119] Manufacturing Example 3. Photocurable oligomer containing polyethylene glycol

[0120] A bifunctional urethane compound having an ethylenically unsaturated double bond and a weight average molecular weight of 1,500 g / mol was obtained using the same method as in Preparation Example 2, except that polyethylene glycol (Sigma Aldrich) was used instead of polypropylene glycol as the diol backbone.

[0121]

[0122] Manufacturing Example 4. Photocurable oligomer containing ethylene oxide-propylene oxide

[0123] A bifunctional urethane compound having an ethylenically unsaturated double bond and a weight average molecular weight of 1,500 g / mol was obtained using the same method as in Preparation Example 2, except that an ethylene oxide-propylene oxide (EO / PO) copolymer (Stepan, MAKON L31) was used instead of polypropylene glycol as the diol backbone.

[0124]

[0125] Manufacturing Example 5. Photocurable oligomer containing ethylene oxide-propylene oxide

[0126] A bifunctional urethane compound having an ethylenically unsaturated double bond and a weight average molecular weight of 2,500 g / mol was obtained using the same method as in Preparation Example 2, except that an ethylene oxide-propylene oxide (EO / PO) copolymer (Stepan, MAKON L61) was used instead of polypropylene glycol as the diol backbone.

[0127]

[0128] <Example>

[0129] Example 1

[0130] A photocurable coating composition was obtained by mixing 20 wt% of a bifunctional urethane compound having an ethylenically unsaturated double bond according to the above Preparation Example 1, 73.4 wt% of monofunctional isobornyl acrylate (CAS: 5888-33-5), 5 wt% of bifunctional dipropylene glycol diacrylate (CAS: 57472-68-1), 1 wt% of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (CAS: 162881-26-7), 0.1 wt% of thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (CAS: 41484-35-9), and 0.5 wt% of polydimethylsiloxane.

[0131]

[0132] Example 2

[0133] A photocurable coating composition was obtained using the same method as in Example 1, except that the compound according to Preparation Example 2 was used instead of the difunctional urethane compound having an ethylenically unsaturated double bond according to Preparation Example 1.

[0134]

[0135] Example 3

[0136] A photocurable coating composition was obtained using the same method as in Example 1, except that the compound according to Preparation Example 3 was used instead of the difunctional urethane compound having an ethylenically unsaturated double bond according to Preparation Example 1.

[0137]

[0138] Example 4

[0139] A photocurable coating composition was obtained using the same method as in Example 1, except that the compound according to Preparation Example 4 was used instead of the difunctional urethane compound having an ethylenically unsaturated double bond according to Preparation Example 1.

[0140]

[0141] Example 5

[0142] A photocurable coating composition was obtained using the same method as in Example 1, except that the compound according to Preparation Example 5 was used instead of the difunctional urethane compound having an ethylenically unsaturated double bond according to Preparation Example 1.

[0143]

[0144] Example 6

[0145] A photocurable coating composition was obtained using the same method as in Example 4, except that the compound according to Manufacturing Example 4 was used in an amount of 30 wt% and monofunctional isobornyl acrylate (CAS: 5888-33-5) in an amount of 63.4 wt%.

[0146]

[0147] Example 7

[0148] A photocurable coating composition was obtained using the same method as in Example 4, except that the compound according to Manufacturing Example 4 was used in an amount of 10 wt% and monofunctional isobornyl acrylate (CAS: 5888-33-5) in an amount of 83.4 wt%.

[0149]

[0150] Comparative Example 1

[0151] A photocurable coating composition was obtained using the same method as in Example 4, except that the compound according to Manufacturing Example 4 was used in an amount of 50 wt% and monofunctional isobornyl acrylate (CAS: 5888-33-5) in an amount of 43.4 wt%.

[0152]

[0153] Comparative Example 2

[0154] A photocurable coating composition was obtained using the same method as Example 4, except that the photocurable oligomer was used in an amount of 0 wt% and monofunctional isobornyl acrylate (CAS: 5888-33-5) was used in an amount of 93.4 wt%.

[0155]

[0156] <Evaluation example>

[0157] The viscosity, surface tension, film properties, peelability, adhesion, high-temperature reliability, surface resistance, and peel voltage of the photocurable coating compositions manufactured according to Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated according to the following methods, and the results are shown in Tables 2 and 3 below.

[0158] 1. Viscosity (cps): Brookfield Viscometer DV2T was used at 25℃.

[0159] 2. Surface tension (dyne / cm2): Measured at 25°C using a Sigma 702 surface tension meter (Biolin Scientific) using a platinum Du Nouy ring.

[0160] 3. Film properties: Film properties were confirmed through manual peelability and bendability evaluations using hands immediately after production.

[0161] 4. Peelability (initial peeling): If peeling was successful after 1 to 2 attempts from the substrate, it was evaluated as “good”, if it was successful after 3 or more attempts, it was evaluated as “insufficient”, and if no peeling occurred, it was evaluated as “poor”.

[0162] 5. Adhesion (gf / inch): The specimen adhered to a glass plate coated with PI film was measured using a universal tensile tester (Yeonjin Corporation TXA-Texture Analyzer) at 30 mm / min according to the 180˚peel test method.

[0163] 6. High-temperature reliability (film properties over time): After being stored in a high-temperature chamber at 85℃ for 500 hours, the film's changes over time were observed through a sensory evaluation of manual peelability and bendability using hands.

[0164] 7. Surface resistance (Ω): Surface resistance was measured at 100 V using TREK 152-1.

[0165] 8. Peeling voltage (kV): The film coated on the glass plate was manually peeled using TREK P0884A, and the resulting voltage was measured.

[0166]

[0167] [Table 2]

[0168]

[0169] As can be seen from Table 2 above, the photocurable coating compositions (Examples 1 to 5) comprising the oligomers of Preparation Examples 1 to 4, which include a copolymer of polybutadiene polyol, polypropylene glycol, polyethylene glycol, ethylene oxide, and propylene oxide as a diol backbone, were found to have excellent initial peeling, high-temperature reliability, and surface resistance with a low viscosity of 20 cps or less and a low adhesion of 5 kgf / inch or less.

[0170] Meanwhile, even though the photocurable coating composition includes the oligomers of Preparation Examples 4 and 5 containing EO / PO as the diol backbone, the photocurable coating composition according to Example 4, in which the weight average molecular weight of the photocurable oligomer is 1,500, was confirmed to have a lower viscosity of 14 cps and better ejectability and peelability than Example 5, in which the weight average molecular weight of the photocurable oligomer is 2,500.

[0171]

[0172] [Table 3]

[0173]

[0174] As can be seen from Table 3 above, Comparative Example 1, which contains 50 wt% of a copolymer of ethylene oxide and propylene oxide as a diol backbone, had a high viscosity of 30 chen, poor film properties, peelability, and high-temperature reliability, and high adhesion of 7 kgf / inch or more, while Comparative Example 2, which does not contain a copolymer of ethylene oxide and propylene oxide as a diol backbone, had poor film properties, peelability, adhesion, and high-temperature reliability, whereas Examples 4, 6, and 7, which contain 10 to 30 wt% of a copolymer of ethylene oxide and propylene oxide as a diol backbone, had a low viscosity of 20 cps or less, and low adhesion of 5 kgf / inch or less, and were confirmed to have excellent initial peeling, high-temperature reliability, and surface resistance.

[0175]

[0176] While specific aspects of the present invention have been described in detail above, it should be apparent to those skilled in the art that these specific descriptions are merely preferred implementation examples and are not intended to limit the scope of the present invention. Therefore, the substantial scope of the present invention is defined by the appended claims and their equivalents.

[0177]

[0178] The photocurable coating composition according to the present invention is expected to be used as a protective film that not only has excellent adhesion to a display panel even with low adhesion (5 kgf / inch or less), but also has a modulus of 1 GPa, secures film properties, and is easy to peel.

Claims

1. (A) 1 to 50 wt% of photocurable bifunctional urethane (meth)acrylate oligomer, (B) 70 to 90 wt% of photocurable (meth)acrylate monomer, (C) 0.1 to 10 wt% of photopolymerization initiator, (D) 0.001 to 5 wt% of antioxidant, and (E) A photocurable coating composition comprising 0.1 to 5 wt% of a surface additive.

2. In paragraph 1, A photocurable coating composition, characterized in that the photocurable bifunctional urethane (meth)acrylate oligomer (A) has a weight average molecular weight of 1,000 to 2,500 g / mol.

3. In paragraph 1, A photocurable coating composition, characterized in that the above (A) photocurable bifunctional urethane (meth)acrylate oligomer is synthesized from a composition comprising (i) a polyolefin polyol or a polyether polyol, (ii) an isocyanate component, (iii) a urethane reaction catalyst, and (iv) a polymerization inhibitor.

4. In paragraph 3, A photocurable coating composition, characterized in that the polyol comprises a copolymer of polybutadiene polyol, polypropylene glycol, polyethylene glycol, ethylene oxide and propylene oxide.

5. In paragraph 3, The above isocyanate component is C1 to C 20 A photocurable coating composition characterized in that it comprises at least one selected from the group consisting of alkyl isocyanate, 2-isocyanatoethyl methacrylate, allyl isocyanate, and 3-isopropenyl-α,α-dimethylbenzyl isocyanate.

6. In paragraph 3, A photocurable coating composition, characterized in that the urethane reaction catalyst comprises at least one selected from the group consisting of copper naphthlenate, cobalt naphthinate, zinc naphthate, n-butyltinlaurate, tristhylamine, and 2-methyltriethylenediamide.

7. In paragraph 3, A photocurable coating composition, characterized in that the polymerization inhibitor comprises at least one selected from the group consisting of butylated hydroxytoluene (BHT), hydroquinone, hydroquinone monomethyl ether, para-benzoquinone, and phenothiazine.

8. In paragraph 1, A photocurable coating composition, characterized in that the above (B) photocurable (meth)acrylate monomer comprises 65 to 75 wt% of (B-1) monofunctional (meth)acrylate and 5 to 15 wt% of (B-2) polyfunctional (meth)acrylate based on the total weight of the photocurable coating composition.

9. In paragraph 8, A photocurable coating composition, characterized in that the above (B-1) monofunctional (meth)acrylate is isobornyl acrylate, and the above (B-2) polyfunctional (meth)acrylate is dipropylene glycol diacrylate.

10. In paragraph 1, A photocurable coating composition, characterized in that the above (C) photopolymerization initiator is at least one selected from the group consisting of benzoin-based, hydroxy ketone-based, amino ketone-based, and phosphine oxide-based photoinitiators.

11. In paragraph 1, A photocurable coating composition, characterized in that the above (C) photopolymerization initiator is phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

12. In paragraph 1, A photocurable coating composition, characterized in that the above (D) antioxidant is at least one selected from the group consisting of a phenol-based antioxidant, a sulfur-based antioxidant, and a phosphorus-based antioxidant.

13. In paragraph 1, A photocurable coating composition, characterized in that the above (D) antioxidant is thiodiethylene bis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate].

14. In paragraph 1, A photocurable coating composition, characterized in that the above (E) surface additive is at least one selected from the group consisting of a polyacrylate-based surfactant, a silicone-containing surfactant, and an acrylic-based surfactant.

15. In paragraph 1, The photocurable coating composition is characterized in that it further comprises at least one additive selected from the group consisting of a silane coupling agent, an adhesion promoter, a heat polymerization inhibitor, a saturated fatty acid having 8 or more carbon atoms, an antistatic agent, a catalyst, a resin component other than a urethane resin, an inorganic filler, an organic filler, a metal powder, a pigment, a softener, a plasticizer, an anti-aging agent, a conductive agent, an antioxidant, a UV absorber, a light stabilizer, a surface lubricant, a leveling agent, a corrosion inhibitor, a heat stabilizer, a polymerization inhibitor, a lubricant, and a solvent.

16. In paragraph 1, A photocurable coating composition, characterized in that the viscosity of the photocurable coating composition is 10 to 20 cps (25°C).

17. A coating film formed using a photocurable coating composition according to any one of claims 1 to 16.

18. In paragraph 17, A coating film characterized in that the coating film is attached to at least one display device selected from the group consisting of a plasma display, a field emission display, an organic EL display, an inorganic EL display, and electronic paper.

19. In paragraph 17, A coating film, characterized in that the peeling force of the coating film is 1 to 7 gf / inch.

20. In paragraph 17, The surface resistance of the above coating film is 10 12 10 inland 15 A coating film characterized by having a density of Ω / sq.

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