Curable composition for forming a hard coat layer comprising urethane (meth)acrylate and surface-modified silica particles

Abstract

The present invention provides a hard coat forming material having excellent scratch resistance and stretchability, both of which exhibit a trade-off. The means for solving the problem is a curable composition comprising: (a) 100 parts by mass of a urethane (meth)acrylate; (b) 5 to 70 parts by mass of silica particles surface-modified with a silane coupling agent having at least one nitrogen-containing proton-donating group selected from an amino group, an amide group, a urea group, a thiurea group, a thiourethane group, a urea group, and a thiourea group; (c) 0.05 to 10 parts by mass of a perfluoropolyether having an active energy ray-polymerizable group at the end of a molecular chain containing a poly(perfluorooxyalkylene) group; and (d) 1 to 20 parts by mass of a polymerization initiator that generates free radicals in response to active energy rays.

Description

Technical Field

[0001] The present invention relates to a curable composition useful as a material for forming a hard coat layer applied to the surface of various display elements such as flexible displays, and relates to a curable composition that has excellent scratch resistance and stretchability, can also impart antistatic properties, and can form a hard coat layer. Background Art

[0002] Smartphones are now the most common form of mobile phone and have become an indispensable part of our daily lives. In order to prevent damage to the display, protective glass is used on the surface of the smartphone. In recent years, bendable displays, i.e. flexible displays, have been developed as the above-mentioned displays. Flexible displays are expected to have a wide range of uses as displays that can be deformed, such as by bending and rolling. However, in general, glass is hard and difficult to bend back, so it cannot be used in flexible displays. Therefore, attempts have been made to apply a plastic film with a scratch-resistant hard coating for preventing scratches to the surface of the flexible display instead of glass. For a flexible display having a plastic film with such a hard coating applied to the surface, when the display side is bent as the outside (i.e., with the hard coating as the outside), stress in the tensile direction is generated in the hard coating on the top surface, so the hard coating is required to have a certain degree of stretchability.

[0003] In addition, methods commonly used to impart scratch resistance to hard coatings include, for example, increasing surface hardness and imparting resistance to external forces by forming a high-density cross-linked structure, i.e., a cross-linked structure with low molecular mobility. Currently, the most commonly used materials for these hard coatings are multifunctional acrylates that undergo three-dimensional cross-linking via free radicals. However, due to their high cross-linking density, multifunctional acrylates typically have poor stretchability. Therefore, the stretchability and scratch resistance of a hard coating are in a trade-off relationship, and achieving both properties becomes a challenge.

[0004] One known method for improving scratch resistance is to add silicone or fluorine-based surface modifiers to the curable composition forming the hard coat layer to impart slip properties to the cured film surface. Furthermore, a hard coat technology has been reported that achieves both scratch resistance and stretchability by combining a multifunctional acrylate and high-hardness silica fine particles (Patent Document 1).

[0005] On the other hand, when using a hard coat film as a front protective material for a display, it is sometimes required to impart antistatic properties in order to suppress the adhesion of dust and the like caused by static electricity generated during lamination and to prevent operational failures of the display. As such an antistatic measure, a surface resistance value of 10 10 Ω / □ or so.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-131409 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] In the hard coating layer containing silica particles described in Patent Document 1, which has been previously proposed, the physical interaction between the multifunctional acrylate and the silica particles is weak, making it difficult to achieve sufficient scratch resistance and unsatisfactory stretchability. The present invention aims to provide a curable composition capable of forming a hard coating layer that achieves both scratch resistance and stretchability while also imparting antistatic properties.

[0011] Means of solving the problem

[0012] The first embodiment of the present invention is a curable composition comprising

[0013] (a) 100 parts by mass of urethane (meth)acrylate, (b) 5 to 70 parts by mass of silica particles surface-modified with a silane coupling agent having at least one nitrogen-containing proton-donating group selected from an amino group, an amide group, a urea group, a thiurea group, a thiourethane group, a urea group, and a thiourea group; (c) 0.05 to 10 parts by mass of a perfluoropolyether having an active energy ray-polymerizable group at the end of a molecular chain containing a poly(perfluorooxyalkylene) group; and (d) 1 to 20 parts by mass of a polymerization initiator that generates free radicals responsive to active energy rays.

[0014] The (a) urethane (meth)acrylate is, for example, a reaction product of (a1) a (meth)acrylate compound having at least one hydroxyl group and (a2) an isocyanate compound having at least two isocyanate groups.

[0015] The isocyanate compound (a2) is, for example, at least one compound selected from the group consisting of compounds represented by the following formulas [1] to [4].

[0016]

[0017] In the above formula, R 1 、R 2 、R 3 and R 4 Each represents a hydrocarbon group having 4 to 12 carbon atoms, R 0 Represents the residue of a monohydric alcohol, R 5 represents a hydrocarbon group having 2 to 6 carbon atoms, and m represents 2, 3 or 4.

[0018] The urethane (meth)acrylate (a) includes, for example, at least one urethane (meth)acrylate having any one of the partial structures represented by the following formula [1′] to formula [4′].

[0019]

[0020] In the above formula, R 1 、R 2 、R 3 and R 4 Each represents a hydrocarbon group having 4 to 12 carbon atoms, R 0 Represents the residue of a monohydric alcohol, R 5 represents a hydrocarbon group having 2 to 6 carbon atoms, and m represents 2, 3 or 4.

[0021] The silica particles (b) are formed by modifying the surface of silica fine particles having an average particle diameter of 40 nm to 500 nm with the silane coupling agent having a nitrogen-containing proton-donating group.

[0022] The nitrogen-containing proton-donating group is preferably at least one group selected from the group consisting of a urea group, a thiourea group, and a urea group.

[0023] The (c) perfluoropolyether has an active energy ray-polymerizable group at the terminal of the molecular chain containing the poly(perfluorooxyalkylene) group, for example, via a urethane bond.

[0024] The perfluoropolyether (c) has at least two active energy ray-polymerizable groups at the terminal of the molecular chain containing the poly(perfluorooxyalkylene) group, for example, via a urethane bond.

[0025] The perfluoropolyether (c) has at least two active energy ray-polymerizable groups at both ends of the molecular chain containing the poly(perfluorooxyalkylene) group, for example, via urethane bonds.

[0026] The poly(perfluorooxyalkylene) group of the above-mentioned perfluoropolyether (c) has, for example, a repeating unit -[CF2O]- and / or a repeating unit -[CF2CF2O]-. When having two types of repeating units, the group is formed by bonding these repeating units by block bonding, random bonding, or block bonding and random bonding.

[0027] The molecular chain containing the poly(perfluoroalkylene oxide) group has a structure represented by the following formula [5], for example:

[0028]

[0029] In the above formula [5], n is the sum of the number of repeating units -[CF2CF2O]- and the number of repeating units -[CF2O]-, and represents an integer of 5 to 30, and the repeating units -[CF2CF2O]- and the repeating units -[CF2O]- are formed by block bonding, random bonding, or block bonding and random bonding.

[0030] The curable composition of the present invention may further include (e) an antistatic agent. The antistatic agent (e) includes, for example, metal oxide particles. The metal oxide particles include, for example, an oxide of at least one element selected from the group consisting of tin, zinc, and indium. The metal oxide particles include, for example, tin oxide to which a dopant may be added. The metal oxide particles include, for example, at least one of phosphorus-doped tin oxide and tin oxide coated with antimony pentoxide.

[0031] The curable composition of the present invention may further contain (f) a solvent.

[0032] A second embodiment of the present invention is a cured film obtained from the curable composition of the present invention.

[0033] A third aspect of the present invention is a hard coat film comprising a hard coat layer on at least one surface of a film substrate, wherein the hard coat layer is composed of a cured film obtained from the curable composition of the present invention.

[0034] The hard coat layer is formed, for example, by a method comprising the steps of applying the curable composition of the present invention on a film substrate to form a coating film, and irradiating the coating film with active energy rays to cure the coating film.

[0035] The hard coat layer is formed, for example, by a method comprising the steps of applying the curable composition of the present invention on a film substrate to form a coating film, removing the solvent from the coating film by heating, and curing the coating film by irradiating the coating film with active energy rays.

[0036] The hard coat layer has a film thickness of, for example, 1 μm to 20 μm.

[0037] A fourth aspect of the present invention is a method for producing a laminate, comprising the steps of applying the curable composition of the present invention on a film substrate to form a coating film, and irradiating the coating film with active energy rays to cure the coating film.

[0038] Effects of the Invention

[0039] The present invention provides a curable composition useful for forming a cured film or hard coating layer that exhibits both excellent scratch resistance and high stretchability, even in films with a thickness of 1 μm to 20 μm. Furthermore, the present invention provides a hard coating layer comprising a cured film obtained from the curable composition or a hard coating layer formed from the cured film, thereby providing a hard coating layer exhibiting both excellent scratch resistance and excellent stretchability, which are trade-offs. Furthermore, the present invention provides a curable composition useful for forming a cured film or hard coating layer that imparts antistatic properties in addition to the aforementioned scratch resistance and stretchability, and a hard coating layer exhibiting these three excellent properties. DETAILED DESCRIPTION

[0040] <Curable Composition>

[0041] Hereinafter, each component of the curable composition of the present invention will be described.

[0042] [(a) Urethane (meth)acrylate]

[0043] In the curable composition of the present invention, the urethane (meth)acrylate (a) is not particularly limited as long as it is a compound having at least two (meth)acryloyl groups and at least one urethane bond [—NH—C(═O)O—] per molecule. The urethane (meth)acrylate (a) is, for example, a reaction product obtained by reacting (a1) a (meth)acrylate compound having at least one hydroxyl group with (a2) an isocyanate compound having at least two isocyanate groups using a known method.

[0044] Examples of the (meth)acrylate compound (a1) having at least one hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-(2-hydroxyethoxy)ethyl acrylate, 2-(2-hydroxyethoxy)ethyl methacrylate, glycerol diacrylate, glycerol dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol pentamethacrylate.

[0045] Examples of the isocyanate compound (a2) having at least two isocyanate groups include tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, dicyclohexylmethane 4,4'-diisocyanate, 2, 2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, and allophanate polyisocyanates represented by the above formula [1] obtained by polymerizing these diisocyanates, biuret polyisocyanates represented by the above formula [2], adduct polyisocyanates represented by the above formula [3], and isocyanurate polyisocyanates represented by the above formula [4].

[0046] In the above formulas [1] to [4], R 1 、R 2 、R 3 and R 4 The group obtained by removing two isocyanate groups from the above diisocyanate may include, for example, hexamethylene. 0 It is a group obtained by removing an OH group from a monohydric alcohol that reacts with the above-mentioned diisocyanate to form a urethane bond. 5 These are groups obtained by removing all OH groups from a diol, triol, or tetraol that reacts with the above-mentioned diisocyanate to form a urethane bond.

[0047] As the (a) urethane (meth)acrylate, commercially available products can be used, and examples thereof include ART RESIN (registered trademark) UN-3320HA, ART RESIN UN-3320HC, ART RESIN UN-3320HS, ART RESIN UN-904, ART RESIN UN-906S, ART RESIN UN-901T, ART RESIN UN-905, and ART RESIN UN-952 (all manufactured by Negami Industries, Ltd.), EBECRYL (registered trademark) 220, EBECRYL 284, EBECRYL 4683, EBECRYL 4858, EBECRYL 8807, EBECRYL 4220, EBECRYL 4738, EBECRYL 4820, EBECRYL 8311, EBECRYL 8465, EBECRYL 9260, and EBECRYL 8701、EBECRYL 4265、EBECRYL 4666、EBECRYL 1290, EBECRYL5129, KRM8667, KRM8200, KRM8200AE, KRM8530, KRM8904, KRM8531BA, KRM8452 (all manufactured by Daicel Ornex Co., Ltd.), UA-306H, UA-306T, UA-306I, UA-510H, UF-8001G (all manufactured by Kyoeisha Chemical Co., Ltd.), ARONIX (registered trademark) M-1100, ARONIX M-1200 (all manufactured by Toagosei Co., Ltd.), and U-6LPA, U-10HA, U-10PA, UA-1100H, U-15HA, UA-53H, UA-33H, UA-122P (all manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0048] The (a) urethane (meth)acrylate in the curable composition of the present invention may be used alone or in combination of two or more.

[0049] [(b) Silica particles]

[0050] In the curable composition of the present invention, the surface of the (b) silica particles is modified with a silane coupling agent having at least one nitrogen-containing proton-donating group selected from the group consisting of an amino group, an amide group, a urea group, a thiurea group, a thiourethane group, a urea group, and a thiourea group. Furthermore, the (b) silica particles can impart stretchability without impairing scratch resistance through interaction with the (a) urethane (meth)acrylate.

[0051] The shape of the silica particles before their surfaces are modified with a silane coupling agent having nitrogen-containing proton-donating groups (hereinafter referred to as "unmodified silica particles") is not particularly limited. For example, they may be approximately spherical, such as beads, or may be irregular shapes such as powders. Approximately spherical particles are preferred, approximately spherical particles having an aspect ratio of 1.5 or less are more preferred, and truly spherical particles are most preferred.

[0052] In addition, the average particle size of the unmodified silica particles is in the range of 40 nm to 500 nm, for example, 40 nm to 350 nm, preferably in the range of 60 nm to 250 nm, or 70 nm to 250 nm. The average particle size (nm) here refers to the 50% volume diameter (median particle size) obtained by measuring the laser diffraction scattering method based on Mie theory. By setting the average particle size of the (b) silica particles within the above numerical range, a cured film with excellent scratch resistance can be obtained. It should be noted that there is no particular restriction on the particle size distribution of the (b) silica particles, and preferably monodispersed particles with consistent particle size. Furthermore, the average particle size of the (b) silica particles is preferably selected in the following manner, that is, relative to the film thickness of the cured film obtained by the curable composition of the present invention described later, the range of average particle size b / film thickness a=0.01 to 1.0 is satisfied.

[0053] As unmodified silica particles, for example, colloidal silica having the above-mentioned average particle size can be preferably used, and as the colloidal silica, silica sol can be used. As the silica sol, aqueous silica sol prepared by a known method using an aqueous sodium silicate solution as a raw material, and organic silica sol obtained by replacing the water serving as the dispersion medium of the aqueous silica sol with an organic solvent can be used. In addition, silica sol obtained by hydrolyzing and condensing alkoxysilanes such as methyl silicate and ethyl silicate in an organic solvent such as an alcohol in the presence of a catalyst (e.g., an alkaline catalyst such as ammonia, an organic amine compound, or sodium hydroxide) or organic silica sol obtained by replacing the solvent of the silica sol with another organic solvent can also be used.

[0054] Examples of the organic solvent in the organic silica sol include lower alcohols such as methanol, ethanol, and 2-propanol; ketones such as methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK); linear amides such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc); cyclic amides such as N-methyl-2-pyrrolidone (NMP); ethers such as γ-butyrolactone; glycols such as ethyl cellosolve and ethylene glycol; and acetonitrile. The water used as the dispersion medium in the aqueous silica sol can be replaced with an organic solvent, or with another desired organic solvent, by conventional methods such as distillation and ultrafiltration. The viscosity of the organic silica sol at 20°C is, for example, 0.6 to 100 mPa·s.

[0055] Examples of commercially available products of the aqueous silica sol and the organic silica sol include the SilHoste (registered trademark) KE series [manufactured by Nippon Shokubai Co., Ltd.] and the Snotex (registered trademark) series [manufactured by Nissan Chemical Industries, Ltd.].

[0056] Examples of the nitrogen-containing proton-donating group include an amino group, an amide group (-C(=O)NH- group), a urea group (-NHC(=O)NH- group), a thiourea group (-NHC(=S)NH- group), a thiocarbamate group (-NHC(=S)S- group), a urea group (-NHC(=O)NH2 group), and a thiourea group (-NHC(=S)NH2 group). Of these nitrogen-containing proton-donating groups, amino groups, urea groups, thiourea groups, and urea groups are preferred. Considering the transparency of the cured film, urea groups, thiourea groups, and urea groups are particularly preferred. The silane coupling agent used for surface modification of unmodified silica particles may have one or more of the above-mentioned nitrogen-containing proton-donating groups, or may have multiple nitrogen-containing proton-donating groups.

[0057] (b) Silica particles can be prepared by mixing the above-mentioned silane coupling agent having a nitrogen-containing proton-donating group with unmodified silica particles in the presence of water or alcohol. The above-mentioned silane coupling agent having a nitrogen-containing proton-donating group generates a silanol group by hydrolysis, and undergoes a condensation reaction with the silanol group present on the surface of the unmodified silica particles to form a bond. As a result, it is considered that silica particles whose surfaces are modified by the above-mentioned silane coupling agent having a nitrogen-containing proton-donating group are formed. Specifically, for example, by mixing a colloidal solution (silica sol) of unmodified silica particles with the above-mentioned silane coupling agent having a nitrogen-containing proton-donating functional group, silica particles whose surfaces are modified by the silane coupling agent can be prepared. The mixing of the colloidal solution and the above-mentioned silane coupling agent is carried out at room temperature or while heating. From the perspective of reaction efficiency, it is preferred to mix while heating. In the case of mixing while heating, the heating temperature can be appropriately selected according to the type of solvent. The heating temperature can be set to, for example, 30° C. or higher. The mixing ratio of the silane coupling agent having a nitrogen-containing proton-donating functional group and the unmodified silica particles also depends on the size of the unmodified silica particles and the type of the nitrogen-containing proton-donating functional group. For example, the mixing ratio is 100% relative to the unit area (1 nm) of the surface of the unmodified silica particles. 2 ), the number of molecules of the silane coupling agent is 0.01 to 5, preferably 0.05 to 2, and more preferably 0.1 to 1. Here, the surface area of ​​the unmodified silica particles is calculated from the specific surface area measured by the nitrogen adsorption method (BET method).

[0058] In the curable composition of the present invention, the content of the (b) silica particles is 5 to 70 parts by mass, for example, 10 to 60 parts by mass, and preferably 10 to 50 parts by mass, relative to 100 parts by mass of the (a) urethane (meth)acrylate. The (b) silica particles may be used alone or in combination of two or more.

[0059] [(c) Perfluoropolyether]

[0060] The preferred (c) perfluoropolyether in the curable composition of the present invention has an active energy ray polymerizable group at the end of the molecular chain containing the poly(perfluorooxyalkylene) group via a urethane bond. The end of the molecular chain of the above-mentioned perfluoropolyether can be any one of all the ends and a part of the ends of the molecular chain. In the case where the molecular chain of the perfluoropolyether is linear, all the ends and a part of the ends of the molecular chain are the two ends and a single end of the linear molecular chain, respectively. As the connecting group between the above-mentioned poly(perfluorooxyalkylene) group and the above-mentioned urethane bond, for example, a hydrocarbon group having an ether bond can be cited, and at least one hydrogen atom of the hydrocarbon group can be substituted by a fluorine atom. In the curable composition of the present invention, the (c) perfluoropolyether plays the role of a surface modifier in the hard coating layer formed by the curable composition of the present invention. In addition, the (c) perfluoropolyether has excellent compatibility with the (a) urethane (meth) acrylate, so it can suppress white turbidity and form a hard coating layer with a transparent appearance.

[0061] The poly(perfluoroalkylene oxide) group preferably comprises both -[CF2O]-(oxyperfluoromethylene) and -[CF2CF2O]-(oxyperfluoroethylene) as repeating units, from the perspective of obtaining a cured film having excellent scratch resistance. In this case, the perfluoroalkylene oxide bonds may be either block bonds or random bonds. The total number of repeating units of the perfluoroalkylene oxide is preferably in the range of 5 to 30, and more preferably in the range of 7 to 21.

[0062] The molecular chain containing the poly(perfluorooxyalkylene) group preferably has a structure represented by the following formula [5].

[0063]

[0064] In formula [5], n represents the sum of the number of repeating units -[CF2CF2O]- and the number of repeating units -[CF2O]-, and is preferably an integer in the range of 5 to 30, and more preferably an integer in the range of 7 to 21. Furthermore, the ratio of the number of repeating units -[CF2CF2O]- to the number of repeating units -[CF2O]- is preferably in the range of 2:1 to 1:2, and more preferably in the range of about 1:1. The bonding of these repeating units may be either block bonding or random bonding.

[0065] Examples of the above-mentioned active energy ray polymerizable groups include (meth)acryloyl and vinyl groups. (c) Perfluoropolyether is not limited to perfluoropolyethers having one active energy ray polymerizable group at the end of the molecular chain containing a poly(perfluorooxyalkylene) group, but may also have two or more active energy ray polymerizable groups. Examples of the terminal structure containing an active energy ray polymerizable group include the structures of formula [A1] to formula [A5] shown below, and structures obtained by replacing the acryloyl group in these structures with a methacryloyl group. Among these structures, preferred are structures of formula [A3], formula [A4], and formula [A5] having two or more active energy ray polymerizable groups, and structures obtained by replacing the acryloyl group in these structures with a methacryloyl group.

[0066]

[0067] In the curable composition of the present invention, the content of the (c) perfluoropolyether is 0.05 to 10 parts by mass, preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of the (a) urethane (meth)acrylate. By setting the content of the (c) perfluoropolyether to 0.05 parts by mass or greater, sufficient scratch resistance can be imparted to the hard coating layer. Furthermore, by setting the content of the (c) perfluoropolyether to 10 parts by mass or less, a hard coating layer that is fully compatible with the (a) urethane (meth)acrylate and exhibits less white turbidity can be obtained.

[0068] It should be noted that (c) perfluoropolyether can be used alone or in combination of two or more. When two or more are used in combination, the following perfluoropolyether may be included, which has an active energy ray polymerizable group via a carbamate bond at a single end (one end) of a molecular chain containing a poly(perfluorooxyalkylene) group, and a hydroxyl group at the other end (the other end) of the molecular chain. In addition, the following conditions may be added to the perfluoropolyether (c): there is no poly(oxyalkylene) group between the poly(perfluorooxyalkylene) group and the carbamate bond, and between the poly(perfluorooxyalkylene) group and the hydroxyl group.

[0069] [(d) Polymerization initiator]

[0070] Preferred polymerization initiators (d) in the curable composition of the present invention are polymerization initiators that generate radicals by irradiation with active energy rays such as electron beams, ultraviolet rays, and X-rays, particularly ultraviolet rays.

[0071] As (d) polymerization initiator, for example, benzoin, alkyl phenone, thioxanthone, azo, azide, diazo, o-quinone diazide, acylphosphine oxide, oxime ester, organic peroxide, benzophenone, biscoumarol, diimidazole, titanocene, thiol, halogenated hydrocarbon, trichloromethyl triazine and onium salts such as iodonium salt and sulfonium salt can be listed. These polymerization initiators can be used alone or in combination of two or more. In the present invention, from the perspective of transparency, surface curability and film curability, it is preferred to use alkyl phenone as (d) polymerization initiator. By using alkyl phenone, a cured film with further improved scratch resistance can be obtained.

[0072] Examples of the alkylphenones include α-hydroxyalkylphenones such as 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methylpropane-1-one, and 2-hydroxy-1-[4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl]-2-methylpropane-1-one; α-aminoalkylphenones such as 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butane-1-one; 2,2-dimethoxy-1,2-diphenylethane-1-one; and methyl phenylglyoxylate.

[0073] In the curable composition of the present invention, the content of the (d) polymerization initiator is 1 to 20 parts by mass, preferably 2 to 10 parts by mass, relative to 100 parts by mass of the (a) urethane (meth)acrylate.

[0074] [(e) Antistatic agent]

[0075] The curable composition of the present invention may contain (e) an antistatic agent as an optional component. As the (e) antistatic agent, for example, antistatic agents containing organic conductive polymers or metal oxide particles such as PEDOT / PSS can be cited. As the above-mentioned metal oxide particles, microparticles having a primary particle size of 4 nm to 100 nm can be used. By setting the primary particle size of the above-mentioned metal oxide particles within the above-mentioned numerical range, antistatic properties can be imparted without affecting scratch resistance and stretchability, and a cured film that achieves transparency can also be obtained. It should be noted that, in the present invention, the primary particle size in the metal oxide particles refers to the particle size of each particle observed using a transmission electron microscope.

[0076] The metal oxide particles may include, for example, oxides of at least one element selected from the group consisting of tin, zinc, and indium. Specifically, examples include tin oxide (SnO2), tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), phosphorus-doped tin oxide (PTO), gallium-doped zinc oxide (GZO), aluminum-doped zinc oxide (AlZO), antimony-doped zinc oxide (AZO), indium-doped zinc oxide or zinc oxide-doped indium oxide (IZO), and indium gallium zinc oxide (IGZO). Oxides of the above elements to which a dopant is added are preferred as antistatic agents, with phosphorus-doped tin oxide (PTO) being particularly preferred.

[0077] Examples of the metal oxide particles include surface-coated metal oxide particles having a metal oxide core and coated with an acidic or basic oxide. Examples of the core include, in addition to the metal oxide particles such as tin oxide, titanium oxide, titanium oxide-tin oxide composites, zirconium oxide-tin oxide composites, tungsten oxide-tin oxide composites, and titanium oxide-zirconium oxide-tin oxide composites. Examples of the acidic or basic oxides include antimony pentoxide, silicon oxide-antimony pentoxide composites, and silicon oxide-tin oxide composites.

[0078] When the present invention contains an antistatic agent (e), the content thereof is preferably 10 to 100 parts by mass, more preferably 10 to 90 parts by mass, relative to 100 parts by mass of the urethane (meth)acrylate (a). The antistatic agent (e) may be used alone or in combination of two or more.

[0079] [(f) Solvent]

[0080] The curable composition of the present invention may contain (f) a solvent as an optional component, that is, it may be in the form of a varnish. The solvent (f) may be appropriately selected taking into account the solubility / dispersibility of the aforementioned components (a) to (d) and the optional component (e), as well as the workability during application of the curable composition for forming a cured film (hard coat) described later, and the drying properties before and after curing.

[0081] Examples of the (f) solvent include aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and tetralin; aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, mineral spirits, and cyclohexane; halides such as methyl chloride, methyl bromide, methyl iodide, dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, perchloroethylene, and o-dichlorobenzene; esters or ester ethers such as ethyl acetate, propyl acetate, butyl acetate, methoxybutyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, and propylene glycol monomethyl ether acetate (PGMEA); diethyl ether, tetrahydrofuran (THF), 1,4-dioxane, methyl cellosolve, ethyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether acetate. The present invention also includes ethers such as propylene glycol monoethyl ether (PGME), propylene glycol mono-n-propyl ether, propylene glycol mono-isopropyl ether, and propylene glycol mono-n-butyl ether; ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), di-n-butyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, 2-ethylhexanol, benzyl alcohol, and ethylene glycol; amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP); and sulfoxides such as dimethyl sulfoxide (DMSO), as well as solvents obtained by mixing two or more of these solvents.

[0082] Furthermore, during drying after application of the curable composition, a solvent having a high boiling point may be used for the purpose of controlling the dispersibility of the silica particles (b). Examples of such solvents include cyclohexyl acetate, propylene glycol diacetate, 1,3-butynediol diacetate, 1,4-butanediol diacetate, 1,6-hexanediol diacetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, 3-methoxybutyl acetate, ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, 3-methoxybutanol, dipropylene glycol dimethyl ether, and dipropylene glycol methylpropyl ether.

[0083] In the curable composition of the present invention, the content of the solvent (f) is not particularly limited, and is, for example, a concentration such that the solids concentration of the curable composition of the present invention is 1% by mass to 70% by mass, preferably 5% by mass to 50% by mass. Here, the solids concentration (also referred to as the non-volatile content) represents the content of solids (excluding the solvent component from all components) relative to the total mass (total mass) of the components (a) to (d) above, the optional component (e), the component (f), and other additives of the curable composition of the present invention.

[0084] [Other additives]

[0085] In addition, the curable composition of the present invention may contain conventional additives such as polymerization inhibitors, photosensitizers, leveling agents, surfactants, adhesion-imparting agents, plasticizers, ultraviolet absorbers, storage stabilizers, inorganic fillers, pigments, dyes, etc., alone or in combination of two or more, as long as the effects of the present invention are not impaired.

[0086] <Cured film>

[0087] The curable composition of the present invention is applied (coated) onto a substrate to form a coating film, and the coating film is irradiated with active energy rays to polymerize (cure), thereby forming a cured film, which is also the subject of the present invention. In addition, as the hard coating layer in the hard coating film described below, a hard coating layer composed of the above-mentioned cured film can be used.

[0088] Examples of the substrate include various resins (polycarbonate, polymethacrylate, polystyrene, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyurethane, thermoplastic polyurethane (TPU), polyolefins, polyamides, polyimides, epoxy resins, melamine resins, triacetyl cellulose (TAC), acrylonitrile-butadiene-styrene copolymers (ABS), acrylonitrile-styrene copolymers (AS), and norbornene resins), metals, wood, paper, glass, and stone. These substrates may be in the form of a plate, a film, or a three-dimensional molded body. Furthermore, a primer layer, an ultraviolet absorbing layer, an infrared absorbing layer, a near-infrared absorbing layer, an electromagnetic wave absorbing layer, a color correction layer, a refractive index adjusting layer, a weather-resistant layer, an antireflection layer, an antistatic layer, an anti-discoloration layer, a gas barrier layer, a water vapor barrier layer, a light scattering layer, an electrode layer, and the like may be formed on the surface of the substrate as a lower layer of the hard coating layer, and a plurality of these lower layers of the hard coating layer may be laminated. The layer formed on the surface of the substrate is not particularly limited as long as the effects of the present invention are not impaired.

[0089] The coating method on the above-mentioned substrate can appropriately select cast coating method, spin coating method, blade coating method, dip coating method, roller coating method, spray coating method, rod coating method, die coating method, inkjet method, printing method (letterpress method, gravure printing method, lithography method, screen printing method, etc.), wherein, can be used for roll-to-roll method, in addition, from the aspect of film coating property, preferably use letterpress method, particularly gravure coating method.It should be noted that, preferably using a filter with an aperture of about 0.2 μm in advance, after filtering the curable composition of the present invention, it is used for coating.It should be noted that, during coating, a solvent can be further added to the curable composition as needed.As the solvent in this case, various solvents mentioned in the aforementioned [(f) solvent] can be listed.

[0090] After the curable composition of the present invention is applied to the substrate to form a coating film, the coating film is pre-dried using a heating means such as a hot plate or an oven to remove the solvent as needed (solvent removal process). The heating and drying conditions at this time are preferably set to 40°C to 120°C for about 30 seconds to 10 minutes. After drying, the coating film is cured by irradiation with active energy rays such as ultraviolet rays. Examples of active energy rays include ultraviolet rays, electron beams, and X-rays, with ultraviolet rays being particularly preferred. As light sources used in ultraviolet irradiation, for example, sunlight, chemical lamps, low-pressure mercury lamps, high-pressure mercury lamps, metal halide lamps, xenon lamps, and UV-LEDs can be used. Furthermore, polymerization can be completed by performing post-baking, specifically, by heating using a heating means such as a hot plate or an oven.

[0091] The thickness of the formed cured film after drying and curing is usually 0.1 μm to 50 μm, preferably 0.5 μm to 20 μm.

[0092] <Hard Coat>

[0093] The curable composition of the present invention can be used to prepare a hard coat film having a hard coat layer on at least one side (surface) of a film substrate. This hard coat film is also the subject of the present invention and is suitable for protecting the surfaces of various display devices such as touch panels and liquid crystal displays.

[0094] The hard coat layer in the hard coat film of the present invention can be formed by a method comprising the steps of applying the curable composition of the present invention onto a film substrate to form a coating film, optionally removing the solvent by heating, and curing the coating film by irradiating the coating film with active energy rays such as ultraviolet rays. A method for producing a hard coat film comprising these steps, wherein the hard coat layer is provided on at least one surface of a film substrate, is also subject of the present invention.

[0095] As the film substrate, various transparent resin films that can be used for optical purposes can be used in the substrates listed in the above-mentioned <hardened film>. As preferred resin films, for example, films of polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyurethanes, thermoplastic polyurethanes (TPU), polycarbonates, polymethacrylates, polystyrenes, polyolefins, polyamides, polyimides, triacetyl cellulose (TAC), etc. can be cited. As the above-mentioned film substrate, multiple layers can be laminated and formed. For example, a primer layer, an ultraviolet absorbing layer, an infrared absorbing layer, a near infrared absorbing layer, an electromagnetic wave absorbing layer, a color correction layer, a refractive index adjustment layer, a weathering layer, an antireflection layer, an antistatic layer, an anti-discoloration layer, a gas barrier layer, a water vapor barrier layer, a light scattering layer, an electrode layer, etc. different from the resin films can be laminated as the lower layer of the hard coat layer, or the lower layer of multiple hard coat layers can be laminated. The layer laminated on the surface of the resin film is not particularly limited as long as the effects of the present invention are not impaired.

[0096] In addition, the coating method of the curable composition of the present invention on the above-mentioned film substrate (coating film forming step) and the method of irradiating the coating film with active energy rays (curing step) can use the methods listed in the above <cured film>. In addition, when the curable composition of the present invention contains a solvent (varnish form), after the coating film forming step, a step of drying the coating film to remove the solvent can be included as needed. In this case, the coating film drying method (solvent removal step) listed in the above <cured film> can be used.

[0097] The thickness of the hard coating layer thus obtained is preferably set to 1 to 100 times the average particle size of the silica particles (b). For example, the thickness of the hard coating layer is 1 to 20 μm, preferably 1 to 10 μm.

[0098] Example

[0099] The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to the following Examples. It should be noted that the apparatus and conditions used in sample preparation and physical property analysis in the Examples are as follows.

[0100] (1) Coating using a rod coater

[0101] Device: PM-9050MC manufactured by Esutech Co., Ltd.

[0102] Rod: A-Bar OSP-22 manufactured by Execution Co., Ltd., maximum wet film thickness 22 μm (equivalent to wire rod #9)

[0103] Coating speed: 4m / min

[0104] (2) Oven

[0105] Equipment: 2-layer clean oven (upper and lower type) PO-250-45-D manufactured by Sanki Keiso Co., Ltd.

[0106] (3) UV curing

[0107] Device: CV-110QC-G manufactured by ヘレウス Co., Ltd.

[0108] Lamp: H-bulb, an electrodeless lamp manufactured by Heleus Co., Ltd.

[0109] (4) Gel permeation chromatography (GPC)

[0110] Device: HLC-8220GPC manufactured by Toseo Co., Ltd.

[0111] Column: Shodex (registered trademark) GPC K-804L, GPC K-805L manufactured by Showa Denko K.K.

[0112] Column temperature: 40°C

[0113] Eluent: tetrahydrofuran

[0114] Detector: RI

[0115] (5) Scratch resistance test

[0116] Equipment: TRIBOGEAR TYPE 30S reciprocating wear testing machine manufactured by Shinto Scientific Co., Ltd.

[0117] Travel speed: 5,000 mm / min

[0118] Moving distance 50mm

[0119] (6) Tensile test

[0120] Equipment: Autograph AGS-10kNX, a desktop precision universal testing machine manufactured by Shimadzu Corporation

[0121] Fixture: 1kN manual threaded flat fixture

[0122] Clamping teeth: High strength rubber coated clamping teeth

[0123] Tensile speed: 10mm / min

[0124] Measurement temperature: 23°C

[0125] (7) Surface resistance measurement

[0126] Device: Hiresta UP MCP-HT450, a high resistivity meter manufactured by Nitto Seiko Amanuel Co., Ltd. (formerly Mitsubishi Electric Co., Ltd.)

[0127] Probe: URS probe

[0128] Record table (レジテーブル): UFL

[0129] Applied voltage: 10V

[0130] In addition, the abbreviations have the following meanings.

[0131] Multifunctional acrylate having one hydroxyl group (a1-1):

[0132] Dipentaerythritol pentaacrylate / hexaacrylate mixture [Alonix (registered trademark) M-403 manufactured by Toagosei Co., Ltd., pentaacrylate ratio 50% to 60% (catalog value), estimated hydroxyl value = 63.3 mgKOH / g (calculated based on 55% pentaacrylate and 45% hexaacrylate)]

[0133] Allophanate polyisocyanate (a2-1):

[0134] Allophanate-modified hexamethylene diisocyanate [DURANATE (registered trademark) A201H manufactured by Asahi Kasei Chemicals Co., Ltd., isocyanate group content = 17.2% by mass, bifunctional]

[0135] Biuret polyisocyanate (a2-2):

[0136] Biuret-modified hexamethylene diisocyanate [DURANATE (registered trademark) 24A-100 manufactured by Asahi Kasei Chemicals Co., Ltd., isocyanate group content = 23.5% by mass, trifunctional]

[0137] Isocyanurate polyisocyanate (a2-3):

[0138] Isocyanurate-modified hexamethylene diisocyanate [DURANATE (registered trademark) TLA-100 manufactured by Asahi Kasei Chemicals Co., Ltd., isocyanate group content = 23.3% by mass, trifunctional]

[0139] Adduct polyisocyanate (a2-4):

[0140] Modified adduct of hexamethylene diisocyanate [DURANATE (registered trademark) P301-75E manufactured by Asahi Kasei Chemicals Co., Ltd., isocyanate group content = 12.5% ​​by mass, trifunctional]

[0141] UA5: Urethane acrylate [Art Resin (registered trademark) UN-904 manufactured by Negami Industries, Ltd. (number of functional groups: 10, weight average molecular weight: Mw: 4900)]

[0142] Silica particles s-1:

[0143] Silica fine particles with an average particle size of 80 nm [organic silica sol MA-ST-ZL manufactured by Nissan Chemical Co., Ltd. (solid concentration 30% by mass, methanol dispersion)]

[0144] Silica particles s-2:

[0145] Silica fine particles with an average particle size of 200 nm [organic silica sol MEK-ST-2040 manufactured by Nissan Chemical Co., Ltd. (solid concentration 40% by mass, methyl ethyl ketone dispersion)]

[0146] Silica particles s-3:

[0147] Silica fine particles with an average particle size of 40 nm [organic silica sol MA-ST-L manufactured by Nissan Chemical Co., Ltd. (solid concentration 30% by mass, methanol dispersion)]

[0148] Silane coupling agent Si-1:

[0149] Trimethoxysilane having a thiourea group [X-12-1116 manufactured by Shin-Etsu Chemical Co., Ltd.]

[0150] Silane coupling agent Si-2:

[0151] Urea-containing trimethoxysilane [X-12989MS manufactured by Shin-Etsu Chemical Co., Ltd.]

[0152] Silane coupling agent Si-3:

[0153] 3-Ureidopropyltriethoxysilane [Tokyo Chemical Industry Co., Ltd., solid concentration 50% by mass, alcohol solution]

[0154] Silane coupling agent Si-4:

[0155] Trimethoxysilane having a hexyl group [KBM-3063 manufactured by Shin-Etsu Chemical Co., Ltd.]

[0156] Silane coupling agent Si-5:

[0157] Trimethoxysilane having an acryloyl group [KBM-5103 manufactured by Shin-Etsu Chemical Co., Ltd.]

[0158] PFPE: A perfluoropolyether having two hydroxyl groups at both ends of a molecular chain containing a poly(perfluoroalkylene oxide) group, each without a poly(alkylene oxide) group interposed therebetween [Fomblin (registered trademark) T4 manufactured by Solvay Specialty Polymers Co., Ltd.]

[0159] BEI: 1,1-bis(acryloyloxymethyl)ethyl isocyanate [Showa Denko K.K., Karens (registered trademark) BEI]

[0160] DOTDD: Dioctyltin dineodecanoate [NEOSTANN (registered trademark) U-830 manufactured by Nitto Kasei Co., Ltd.]

[0161] SM2: Perfluoropolyether urethane acrylate having a total of four acryloyl groups at both ends of a molecular chain containing a poly(perfluorooxyalkylene) group [FLUOROLINK (registered trademark) AD-1700 manufactured by Solvay Specialty Polymers, a 70% by mass nonvolatile content solution]

[0162] SM3: Polydimethylsiloxane having a methacryloyl group at one end [Silaplane (registered trademark) FM-0721 manufactured by JNC Corporation]

[0163] O2959: 2-Hydroxy-1-(4-(2-hydroxyethoxy)phenyl)-2-methylpropan-1-one [OMNIRAD (registered trademark) 2959 manufactured by IGM Resins Co., Ltd.]

[0164] MEK: Methyl Ethyl Ketone

[0165] MeOH: methanol

[0166] Antistatic agent e-1:

[0167] 20% by mass phosphorus-doped tin oxide isopropyl alcohol dispersion sol [CELNAX (registered trademark) CX-S204IP manufactured by Nissan Chemical Co., Ltd., primary particle size 5 nm to 20 nm, secondary particle size 10 nm to 20 nm]

[0168] *Herein, the primary particle size and secondary particle size refer to the average particle size measured by transmission electron microscopy. The particle size was determined by dropping the sol onto a copper grid, drying it, and observing it using a transmission electron microscope (JEM-1020, manufactured by JEOL Ltd.) at an accelerating voltage of 100 kV. The average value of 100 particles was measured and used as the average primary particle size.

[0169] Antistatic agent e-2:

[0170] A 30% by mass methanol dispersion sol of core-shell particles with a primary particle size of 30 nm to 40 nm, consisting of tin oxide as the core and antimony pentoxide coating the surface [CELNAX (registered trademark) HX-307M1 manufactured by Nissan Chemical Co., Ltd.]

[0171] [Preparation Example 1] Preparation of surface modifier SM1

[0172] 1.19 g (0.5 mmol) of PFPE, 0.52 g (2.0 mmol) of BEI, 0.017 g of DOTDD (0.01 times the total mass of PFPE and BEI), and 1.67 g of MEK were added to a screw-cap tube. The resulting mixture was stirred at room temperature (approximately 23°C) for 72 hours using a stirrer to obtain a 50% by mass MEK solution of the target surface modifier SM1. The resulting SM1 had a weight average molecular weight (Mw) of 3000, as measured by GPC and converted to polystyrene, and a dispersity (weight average molecular weight (Mw) / number average molecular weight (Mn)) of 1.2.

[0173] [Calculation method of polyisocyanate addition amount when preparing urethane acrylate]

[0174] The amount of polyisocyanate to be added when preparing urethane acrylate by reacting a polyfunctional acrylate (a1-1) having one hydroxyl group with various polyisocyanates (a2-1) to (a2-4) is calculated using [hydroxyl value of (a1-1) / 561]×(42×100 / isocyanate group content)×[amount of (a1-1) / 100]×(number of NCO groups / number of OH groups).

[0175] [Preparation Example 2] Preparation of urethane acrylate UA1

[0176] 10 g of (a1-1) and 2.76 g of allophanate polyisocyanate (a2-1) were added to a screw-cap tube so that the number of OH groups / the number of NCO groups = 1. 0.13 g of DOTDD (0.01 times the total mass of (a1-1) and (a2-1)) and 3.22 g of MEK were then added. The resulting mixture was stirred at room temperature (about 23°C) using a stirrer until 2260 cm-1 of isocyanate groups was reached. -1 The infrared absorption spectrum of disappeared, and then an 80% by mass MEK solution of urethane acrylate UA1 as the target compound was obtained.

[0177] [Preparation Example 3] Preparation of urethane acrylate UA2

[0178] 10 g of (a1-1) and 3.02 g of biuret polyisocyanate (a2-2) were added to a screw-cap tube so that the number of OH groups / the number of NCO groups = 2 / 3. 0.13 g of DOTDD (0.01 times the total mass of (a1-1) and (a2-2)) and 2.96 g of MEK were then added. The resulting mixture was stirred at room temperature (about 23°C) for about 3 hours using a stirrer. 0.33 g of MeOH was added to eliminate the residual isocyanate groups, and the mixture was stirred at room temperature (about 23°C) until the isocyanate group-representing 2260 cm -1 The infrared absorption spectrum of 1% disappeared, and then an 80% by mass MEK / MeOH solution of urethane acrylate UA2 as the target compound was obtained.

[0179] [Preparation Example 4] Preparation of urethane acrylate UA3

[0180] 10 g of (a1-1) and 3.05 g of isocyanurate polyisocyanate (a2-3) were added to a screw-cap tube so that the number of OH groups / the number of NCO groups was 2 / 3. 0.13 g of DOTDD (0.01 times the total mass of (a1-1) and (a2-3)) and 2.97 g of MEK were then added. The resulting mixture was stirred at room temperature (about 23°C) for about 3 hours using a stirrer. 0.33 g of MeOH was added to eliminate any residual isocyanate groups, and the mixture was stirred at room temperature (about 23°C) until a peak of 2260 cm-1, indicating an isocyanate group, was reached. -1 The infrared absorption spectrum of UA3 disappeared, and then an 80% by mass MEK / MeOH solution of urethane acrylate UA3 as the target compound was obtained.

[0181] [Preparation Example 5] Preparation of urethane acrylate UA4

[0182] 10 g of (a1-1) and 3.73 g of the adduct polyisocyanate (a2-4) were added to a screw-cap tube so that the number of OH groups / the number of NCO groups = 1. 0.14 g of DOTDD (0.01 times the total mass of (a1-1) and (a2-4)) and 3.47 g of MEK were then added. The resulting mixture was stirred at room temperature (about 23°C) using a stirrer until the isocyanate group reached 2260 cm -1 The infrared absorption spectrum of 1% disappeared, and then an 80% by mass MEK solution of urethane acrylate UA4 as the target compound was obtained.

[0183] [Preparation Example 6] Preparation of Silica Particles s-4 Surface-Modified with a Silane Coupling Agent Having a Sulfur Urea Group

[0184] A four-necked flask was charged with 35 g of silica fine particles s-1, 0.17 g of silane coupling agent Si-1, and 0.18 g of water. The resulting mixture was stirred at 65°C for 3 hours using a stirrer to obtain a 30% by mass MeOH dispersion of silica fine particles s-4 (the target compound), having an average particle size of 80 nm and surface-modified with a silane coupling agent having a thiourea group.

[0185] [Preparation Example 7] Preparation of Silica Particles s-5 Surface-Modified with a Silane Coupling Agent Having a Urea Group

[0186] 30 g of silica fine particles s-1, 0.15 g of silane coupling agent Si-2, and 0.21 g of water were added to a four-necked flask. The resulting mixture was stirred at room temperature (65°C) for 3 hours using a stirrer to obtain a 30% by mass MeOH dispersion of silica fine particles s-5 (the target compound), having an average particle size of 80 nm and surface-modified with a urea-containing silane coupling agent.

[0187] [Preparation Example 8] Preparation of Silica Particles S-6 Surface-Modified with a Silane Coupling Agent Having a Urea Group

[0188] 30 g of silica fine particles s-1, 0.27 g of silane coupling agent Si-3, and 0.21 g of water were added to a four-necked flask. The resulting mixture was stirred at 65°C for 3 hours using a stirrer to obtain a 30% by mass MeOH dispersion of silica fine particles s-6 (the target compound), having an average particle size of 80 nm and surface-modified with a silane coupling agent having urea groups.

[0189] [Preparation Example 9] Preparation of Silica Particles s-7 Surface-Modified with a Silane Coupling Agent Having a Sulfur Urea Group

[0190] 60 g of silica fine particles s-2, 0.16 g of silane coupling agent Si-1, and 0.55 g of water were added to a four-necked flask. The resulting mixture was stirred at 65°C for 3 hours using a stirrer to obtain a 40% by mass MEK dispersion of silica fine particles s-7 (the target compound), surface-modified with a silane coupling agent containing a thiourea group and having an average particle size of 200 nm.

[0191] [Preparation Example 10] Preparation of Silica Particles S-8 Surface-Modified with a Silane Coupling Agent Having a Sulfur Urea Group

[0192] 35 g of silica fine particles s-3, 0.35 g of silane coupling agent Si-1, and 0.18 g of water were added to a four-necked flask. The resulting mixture was stirred at 65°C for 3 hours using a stirrer to obtain a 30% by mass MeOH dispersion of silica fine particles s-8 (the target compound), surface-modified with a silane coupling agent containing thiourea groups and having an average particle size of 40 nm.

[0193] [Preparation Example 11] Preparation of Silica Particles S-9 Surface-Modified with a Silane Coupling Agent Having an Acryloyl Group

[0194] 30 g of silica fine particles s-1, 0.12 g of silane coupling agent Si-5, and 0.21 g of water were added to a four-necked flask. The resulting mixture was stirred at 65°C for 3 hours using a stirrer to obtain a 30% by mass MeOH-dissolved dispersion of silica fine particles s-9 (the target compound), having an average particle size of 80 nm and surface-modified with a silane coupling agent having an acryl group.

[0195] [Preparation Example 12] Preparation of Silica Particles S-10 Surface-Modified with a Silane Coupling Agent Having a Hexyl Group

[0196] 30 g of silica fine particles s-1, 0.11 g of silane coupling agent Si-4, and 0.21 g of water were added to a four-necked flask. The resulting mixture was stirred at 65°C for 3 hours using a stirrer to obtain a 30% by mass MeOH dispersion of silica fine particles s-10 (the target compound), surface-modified with a hexyl-containing silane coupling agent and having an average particle size of 80 nm.

[0197] [Examples 1 to 11, Comparative Examples 1 to 10]

[0198] The components listed in Table 1 were mixed to prepare curable compositions having the solids concentrations listed in Table 1. It should be noted that the solids herein refer to components other than the solvent and dispersion medium. In Table 1, [parts] represents [parts by mass], and [%] represents [% by mass]. The urethane acrylate, silica fine particles, and surface modifier in Table 1 each represent solids.

[0199] Table 1

[0200]

[0201] These curable compositions were applied using a bar coater onto an A4-sized PET film (Lumirror (registered trademark) U403 (also known as U40), manufactured by Toray Industries, Ltd., 100 μm thick) that had been subjected to an adhesion-facilitating treatment on both sides to form a primer layer, to obtain a coating film. The coating film was dried in an oven at 80°C for 3 minutes to remove the solvent. The resulting film was irradiated under a nitrogen atmosphere at an exposure dose of 300 mJ / cm 2 The hard coating film having a hard coating layer (cured film) was produced by exposure to UV light.

[0202] The homogeneity of each curable composition and the scratch resistance and stretchability of the resulting hard coating film were evaluated. The evaluation procedures are listed below. The results are also shown in Table 2.

[0203] [Composition uniformity]

[0204] The appearance of the curable composition 2 hours after preparation was visually observed and evaluated according to the following criteria.

[0205] A: Clear solution (no suspended matter or sediment)

[0206] C: Both suspended matter and sediment

[0207] [Scratch resistance]

[0208] The hard coat surface of the resulting hard coat film was rubbed 10 times with the load listed in Table 2 using steel wool [Bonster (BONSTAR) (registered trademark) #0000 (ultrafine)] mounted on a reciprocating wear tester over a 60 mm stroke. The extent of damage within the area excluding the 5 mm wide area at both ends of the 60 mm stroke was visually inspected and evaluated according to the following criteria A, B, and C. Note that, assuming actual use as a hard coat, a rating of at least B is required, with A being preferred.

[0209] A: No damage (0 damage)

[0210] B: Damage occurs (1 to 4 damages with a length of 1 mm to 9 mm)

[0211] C: Damage occurs (5 or more damages between 1 mm and 9 mm in length, or 1 or more damages over 1 cm in length)

[0212] [Stretchability]

[0213] The obtained hard coating film was cut into a rectangle with a length of 60 mm and a width of 10 mm to prepare a test piece. The test piece was mounted on the fixture of a universal testing machine by clamping 20 mm from each end in the longitudinal direction, and a tensile test was performed in 1% increments in such a manner that the elongation (= (increase in distance between the clamps) ÷ (distance between the clamps) × 100) became 4%, 5%, and 6%. The hard coating film after the tensile test was visually observed to confirm the maximum elongation at which no cracks were generated in the hard coating layer of the test piece. Then, the elongation of the hard coating film prepared using the curable composition (Comparative Example 1, Comparative Example 7, Comparative Example 8, Comparative Example 9 and Comparative Example 10) from which the silica particles were removed was used as a reference (= 100%), and the elongation improvement rate was calculated. This value was used as the elongation and evaluated according to the following standards A, B and C. It should be noted that, assuming that it is actually used as a hard coating, it is required to be at least B, preferably A.

[0214] A: More than 125%

[0215] B: More than 100% and less than 125%

[0216] C: less than 100%

[0217] Table 2

[0218]

[0219] As shown in Table 1, the curable compositions of Examples 1 to 7 comprised urethane acrylate UA1 having an allophanate structure; silica fine particles s-4, s-5, s-6, s-7, or s-8, each of which had an average particle size of 40 nm, 80 nm, or 200 nm and whose surfaces were modified with a silane coupling agent having a nitrogen-containing proton-donating functional group; and perfluoropolyether SM1 or SM2, each having an acryloyl group at both ends of its molecular chain via a urethane bond, as a surface modifier. Furthermore, as shown in Table 2, the hard coating films comprising the hard coating layer obtained from the curable compositions of Examples 1 to 7 exhibited superior scratch resistance and stretchability compared to the hard coating film comprising the hard coating layer obtained from the curable composition of Comparative Example 1, which did not contain silica fine particles.

[0220] On the other hand, the curable composition of Comparative Example 2 contained urethane acrylate UA1, unsurface-modified silica fine particles s-1, and surface modifier SM1. The hard coating film having a hard coating layer obtained from the curable composition of Comparative Example 2 exhibited inferior scratch resistance compared to the hard coating films having a hard coating layer obtained from the curable compositions of Examples 1 to 7, which contained urethane acrylate UA1, silica fine particles s-4, s-5, or s-6 surface-modified with a silane coupling agent having a thiourea group, a urea group, or a urea group, and surface modifiers SM1 or SM2. This result suggests a weak interaction between urethane acrylate UA1 and silica fine particles s-1.

[0221] Furthermore, the curable composition of Comparative Example 3 contained urethane acrylate UA1, silica fine particles s-9 surface-modified with a silane coupling agent having an acryl group, and surface modifier SM1. The curable composition of Comparative Example 4 contained urethane acrylate UA1, silica fine particles s-10 surface-modified with a silane coupling agent having a hexyl group, and surface modifier SM1. The hard coating film having a hard coating layer obtained from the curable composition of Comparative Example 3 exhibited strong interaction between urethane acrylate UA1 and silica fine particles s-9, resulting in excellent scratch resistance but poor stretchability. Meanwhile, the hard coating film having a hard coating layer obtained from the curable composition of Comparative Example 4 exhibited poor scratch resistance due to weak interaction between urethane acrylate UA1 and silica fine particles s-10.

[0222] On the other hand, in the case of the curable composition of Comparative Example 5, which contained urethane acrylate UA1, silica fine particles s-4 surface-modified with a silane coupling agent having a thiourea group, and polydimethylsiloxane SM3 having a methacryloyl group at one end as a surface modifier, the compatibility of the surface modifier SM3 was poor, and a good composition free of both suspended matter and sediment could not be obtained. Furthermore, the hard coating film having a hard coating layer obtained from the curable composition of Comparative Example 6, which did not contain silica fine particles and a surface modifier, showed poor scratch resistance.

[0223] The hard coat film having a hard coat layer obtained from the curable composition of Example 8 containing urethane acrylate UA2 having a biuret structure, silica fine particles s-4, and surface modifier SM1 exhibited superior scratch resistance and stretchability compared to the hard coat film having a hard coat layer obtained from the curable composition of Comparative Example 7 to which no silica fine particles were added.

[0224] The hard coat film having a hard coat layer obtained from the curable composition of Example 9 containing urethane acrylate UA3 having an isocyanurate structure, silica fine particles s-4, and surface modifier SM1 exhibited superior scratch resistance and stretchability compared to the hard coat film having a hard coat layer obtained from the curable composition of Comparative Example 8 to which no silica fine particles were added.

[0225] The hard coat film having a hard coat layer obtained from the curable composition of Example 10 containing urethane acrylate UA4 having an adduct structure, silica fine particles s-4, and surface modifier SM1 exhibited superior scratch resistance and stretchability compared to the hard coat film having a hard coat layer obtained from the curable composition of Comparative Example 9 to which no silica fine particles were added.

[0226] Furthermore, a hard coat film having a hard coat layer obtained from the curable composition of Example 11, which contained the commercially available urethane acrylate UA5, silica fine particles s-4, and the surface modifier SM1, exhibited comparable scratch resistance and superior stretchability compared to a hard coat film having a hard coat layer obtained from the curable composition of Comparative Example 10, which did not contain silica fine particles. These results suggest that, regardless of the type of urethane acrylate, the addition of silica fine particles s-4, surface-modified with a silane coupling agent containing a thiourea group, can simultaneously improve both scratch resistance and stretchability, which are trade-offs.

[0227] [Example 12 to Example 14]

[0228] The components listed in Table 3 were mixed to prepare curable compositions having the solids concentrations listed in Table 3. It should be noted that the solids herein refer to components other than the solvent and dispersion medium. In Table 3, [parts] represents [parts by mass], and [%] represents [% by mass]. The urethane acrylate, silica fine particles, surface modifier, and antistatic agent in Table 3 each represent solids.

[0229] Table 3

[0230]

[0231] These curable compositions were applied using a bar coater onto an A4-sized PET film (Lumirror (registered trademark) U403 (also known as U40), 100 μm thick, manufactured by Toray Industries, Inc.) that had been subjected to an adhesion-facilitating treatment on both sides to form a primer layer, to obtain a coating film. The coating film was dried in an oven at 60°C for 3 minutes to remove the solvent. The resulting film was irradiated under a nitrogen atmosphere at an exposure dose of 300 mJ / cm 2The film was exposed to UV light of 1000 nm to prepare a hard coat film having a hard coat layer (cured film) having a layer thickness (film thickness) of about 4 μm.

[0232] The obtained hard coating film was evaluated for surface resistance in addition to the aforementioned evaluations of scratch resistance and stretchability. The procedure for surface resistance evaluation is as follows. The results are shown in Table 4.

[0233] [Surface resistance]

[0234] With the hard coat surface facing upward, the hard coat film was placed on the recording table of the high resistivity meter. A probe was pressed against the hard coat film (hard coat layer). The value after 10 seconds was measured three times, and the average value was taken as the surface resistance value [Ω / □].

[0235] Table 4

[0236]

[0237] As shown in Tables 3 and 4, the hard coating films having a hard coating layer obtained from the curable compositions of Examples 12 to 14 using the antistatic agent e-1 or e-2 exhibited excellent scratch resistance and stretchability, and also exhibited antistatic properties.

Claims

1. A curable composition comprising (a) 100 parts by mass of urethane (meth)acrylate, (b) 5 to 70 parts by mass of silica particles surface-modified with a silane coupling agent, wherein the silane coupling agent has at least one nitrogen-containing proton-donating group selected from an amino group, an amide group, a urea group, a thiourea group, a thiocarbamate group, a urea group, and a thiourea group; (c) 0.05 to 10 parts by mass of a perfluoropolyether having at least two active energy ray-polymerizable groups via urethane bonds at the ends of the molecular chains containing poly(perfluorooxyalkylene) groups, and (d) 1 to 20 parts by mass of a polymerization initiator that generates radicals by active energy rays. 2 . The curable composition according to claim 1 , wherein the (a) urethane (meth)acrylate is a reaction product of (a1) a (meth)acrylate compound having at least one hydroxyl group and (a2) an isocyanate compound having at least two isocyanate groups.

3. The curable composition according to claim 2, wherein the isocyanate compound (a2) is at least one compound selected from the group consisting of compounds represented by the following formulas [1] to [4], In the above formula, R 1 、R 2 、R 3 and R 4 Each represents a hydrocarbon group having 4 to 12 carbon atoms, R 0 Represents the residue of a monohydric alcohol, R 5 represents a hydrocarbon group having 2 to 6 carbon atoms, and m represents 2, 3 or 4.

4. The curable composition according to claim 1 or 2, wherein the (a) urethane (meth)acrylate comprises at least one urethane (meth)acrylate having any one of the partial structures represented by the following formulas [1′] to [4′], In the above formula, R 1 、R 2 、R 3 and R 4 Each represents a hydrocarbon group having 4 to 12 carbon atoms, R 0 Represents the residue of a monohydric alcohol, R 5 represents a hydrocarbon group having 2 to 6 carbon atoms, and m represents 2, 3 or 4. 5 . The curable composition according to claim 1 , wherein the silica particles (b) are formed by modifying the surface of silica fine particles having an average particle size of 40 nm to 500 nm with the silane coupling agent having a nitrogen-containing proton-donating group. The curable composition according to claim 1 or 2, wherein the nitrogen-containing proton-donating group is at least one group selected from the group consisting of a urea group, a thiourea group, and a urea group. 7 . The curable composition according to claim 1 , wherein the (c) perfluoropolyether has at least two active energy ray-polymerizable groups at both ends of the molecular chain containing the poly(perfluorooxyalkylene) group, respectively, via a urethane bond.

8. The curable composition according to claim 1 or 2, wherein the poly(perfluorooxyalkylene) group of the perfluoropolyether (c) comprises a repeating unit -[CF2O]- and / or a repeating unit -[CF2CF2O]-, and when comprising both repeating units, the poly(perfluorooxyalkylene) group comprises a group formed by bonding these repeating units via block bonding, random bonding, or both block bonding and random bonding.

9. The curable composition according to claim 8, wherein the molecular chain containing the poly(perfluoroalkylene oxide) group has a structure represented by the following formula [5]: In the above formula [5], n is the sum of the number of repeating units -[CF2CF2O]- and the number of repeating units -[CF2O]-, and represents an integer of 5 to 30, and the repeating units -[CF2CF2O]- and the repeating units -[CF2O]- are formed by block bonding, random bonding, or block bonding and random bonding.

10. The curable composition according to claim 1 or 2, further comprising (e) an antistatic agent. The curable composition according to claim 10 , wherein the (e) antistatic agent comprises metal oxide particles. 12 . The curable composition according to claim 11 , wherein the metal oxide particles comprise an oxide of at least one element selected from the group consisting of tin, zinc, and indium. 13 . The curable composition according to claim 12 , wherein the metal oxide particles comprise tin oxide to which a dopant may be added. The curable composition according to any one of claims 11 to 13, wherein the metal oxide particles comprise at least one of phosphorus-doped tin oxide and tin oxide whose surface is coated with antimony pentoxide.

15. The curable composition according to claim 1 or 2, further comprising (f) a solvent. 16 . A cured film obtained from the curable composition according to claim 1 . 17 . A hard coating film comprising a hard coating layer on at least one surface of a film substrate, wherein the hard coating layer is formed from the cured film according to claim 16 .

18. A hard coat film comprising a hard coat layer on at least one surface of a film substrate, the hard coat layer being formed by a method comprising the steps of applying the curable composition according to any one of claims 1 to 15 on a film substrate to form a coating film, and irradiating the coating film with active energy rays to cure the coating film.

19. A hard coating film comprising a hard coating layer on at least one surface of a film substrate, the hard coating layer being formed by a method comprising the steps of applying the curable composition according to claim 15 onto a film substrate to form a coating film, removing the solvent from the coating film by heating, and curing the coating film by irradiating the coating film with active energy rays. 20 . The hard coating film according to claim 17 , wherein the hard coating layer has a film thickness of 1 μm to 20 μm. 21 . A method for producing a laminate, comprising the steps of applying the curable composition according to claim 1 on a film substrate to form a coating film, and irradiating the coating film with active energy rays to cure the coating film.

Images