TWI896647B - Curable composition for forming a hard coat layer comprising urethane (meth)acrylate and surface-modified silica particles - Google Patents

Abstract

The present invention provides a material for forming a hard coating layer that has a compromise between excellent abrasion resistance and ductility. The curable composition of the present invention comprises: (a) 100 parts by weight of urethane (meth)acrylate; (b) 5 to 70 parts by weight 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 the group consisting of an amine group, an amide group, a urea group, a thiourea group, a thiourethane group, a urea group, and a thiourea group; (c) 0.05 to 10 parts by weight of a perfluoropolyether, wherein the perfluoropolyether has an active energy ray-polymerizable group at the end of a molecular chain containing a poly(oxyperfluoroalkylene) group; and (d) 1 to 20 parts by weight of a polymerization initiator, wherein the polymerization initiator generates free radicals in response to active energy rays.

Description

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

The present invention relates to a curable composition that can be used as a material for forming a hard coating layer on the surface of various display devices such as flexible displays. The present invention also relates to a curable composition that can form a hard coating layer having excellent abrasion resistance and ductility, and can also impart antistatic properties.

Smartphones are now the most common form of mobile phones and have become indispensable in our daily lives. The surface of smartphones uses cover glass to protect the display from damage. In recent years, bendable displays, so-called flexible displays, have been developed as a substitute for the above-mentioned displays. Flexible displays are expected to have a wide range of uses as they can be bent and rolled up. However, glass is usually harder and difficult to bend, so it cannot be used in flexible displays. Therefore, attempts have been made to apply a plastic film with a scratch-resistant hard coating layer to the surface of flexible displays instead of glass. When a flexible display having a plastic film with a hard coating applied to its surface is bent with the display side facing outward (i.e., with the hard coating facing outward), a tensile stress is generated in the hard coating on the outermost surface. Therefore, the hard coating is required to have a certain degree of extensibility.

A common method for imparting scratch resistance to hardcoats is to increase surface hardness by forming a high-density crosslinked structure, i.e., a crosslinked structure with low molecular mobility, thereby imparting resistance to external forces. Currently, the most commonly used materials for these hardcoats are multifunctional acrylate-based materials that undergo three-dimensional crosslinking via free radicals. However, due to their high crosslink density, multifunctional acrylate-based materials generally have poor extensibility. As described above, the present invention aims to achieve a compromise between extensibility and scratch resistance in a hardcoat, achieving a combination of both.

One method for improving abrasion resistance is to add silicone or fluorine-based surface modifiers to the curing composition that forms the hardcoat layer, thereby imparting lubricity to the surface of the cured film. Furthermore, a technique has been reported for achieving a hardcoat with both abrasion resistance and ductility by combining a multifunctional acrylate with high-hardness silica particles (Patent Document 1).

On the other hand, when using hard coat films as a protective material before display applications, anti-static properties are sometimes required to suppress the adhesion of dust and other particles caused by static electricity generated during lamination and prevent display failures. As a countermeasure to this static electricity, a surface resistance of approximately 10 ¹⁰ Ω/□ is desired. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2011-131409

[Identify the problem you want to solve]

Regarding the hard coat layer containing silica microparticles described in previously proposed Patent Document 1, the physical interaction between the multifunctional acrylate and the silica microparticles is weak, making it difficult to achieve sufficient abrasion resistance, and the ductility is also unsatisfactory. The purpose of the present invention is to provide a curable composition capable of forming a hard coat layer that exhibits both abrasion resistance and ductility, and further imparts antistatic properties. [Technical Solution]

The first aspect of the present invention is a curable composition comprising: (a) 100 parts by weight of urethane (meth)acrylate; (b) 5 to 70 parts by weight 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 the group consisting of an amine group, an amide group, a urea group, a thiourea group, a thiourethane group, a urea group, and a thiourea group; (c) 0.05 to 10 parts by weight of a perfluoropolyether, wherein the perfluoropolyether has an active energy ray-polymerizable group at the end of a molecular chain comprising a poly(oxyperfluoroalkylene) group; and (d) 1 to 20 parts by weight of a polymerization initiator, wherein the polymerization initiator generates free radicals in response to active energy rays.

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. The (a2) isocyanate compound is, for example, 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 represent a alkyl group having 4 to 12 carbon atoms, R ⁰ represents a residue of a monohydric alcohol, R ⁵ represents a alkyl group having 2 to 6 carbon atoms, and m represents 2, 3 or 4)

The above-mentioned (a) amine (meth)acrylate includes, for example, at least one amine (meth)acrylate having any one of the partial structures represented by the following formulas [1'] to [4']. [Chemical 2] (In the above formula, R ¹ , R ² , R ³ and R ⁴ each represent a alkyl group having 4 to 12 carbon atoms, R ⁰ represents a residue of a monohydric alcohol, R ⁵ represents a alkyl group having 2 to 6 carbon atoms, and m represents 2, 3 or 4)

The (b) silica particles are, for example, silica particles having an average particle size of 40 nm to 500 nm, the surface of which is modified with a silane coupling agent, wherein the silane coupling agent has the nitrogen-containing proton-donating group.

The nitrogen-containing proton-donating group is preferably at least one group selected from the group consisting of ureylene groups, thioureylene groups, and urea groups.

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

The perfluoropolyether (c) has at least two active energy ray polymerizable groups at the ends of the molecular chain comprising the poly(oxyperfluoroalkylene) group, for example, via a urethane bond.

The perfluoropolyether (c) has at least two active energy ray polymerizable groups at each of the two ends of the molecular chain comprising the poly(oxyperfluoroalkylene) group, for example, via a urethane bond.

The poly(oxyperfluoroalkylene) group of the perfluoropolyether (c) mentioned above has, for example, repeating units -[CF ₂ O]- and/or repeating units -[CF ₂ CF ₂ O]-. When having these two repeating units, the repeating units are linked by block bonding, random bonding, or both block and random bonding.

The molecular chain containing the poly(oxyperfluoroalkylene) group has, for example, a structure represented by the following formula [5]. (In the above formula [5], n is the total number of the repeating units -[CF ₂ CF ₂ O]- and the repeating units -[CF ₂ O]-, and represents an integer of 5 to 30. The repeating units -[CF ₂ CF ₂ O]- and the repeating units -[CF ₂ O]- are bonded to each other by block bonding, random bonding, or block bonding and random bonding.)

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

The curable composition of the present invention may further comprise (f) a solvent.

A second aspect of the present invention is a cured film obtained from the curable composition of the present invention.

A third aspect of the present invention is a hardcoat film comprising a hardcoat layer formed on at least one surface of a film substrate, wherein the hardcoat layer comprises a cured film obtained from the curable composition of the present invention.

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

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

The hard coating layer has a thickness of, for example, 1 μm to 20 μm.

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

The present invention provides a curable composition that can be used to form a cured film or hardcoat layer that exhibits both excellent abrasion resistance and high elongation, even in thin films with a thickness of 1 μm to 20 μm. Furthermore, the present invention provides a cured film obtained from the curable composition, or a hardcoat layer comprising the cured film, that can provide a hardcoat layer exhibiting a compromise between excellent abrasion resistance and elongation. Furthermore, the present invention provides a curable composition that can be used to form a cured film or hardcoat layer that imparts antistatic properties in addition to the aforementioned abrasion resistance and elongation, and a hardcoat layer exhibiting these three excellent properties.

<Curing Composition> The following describes the components of the curable composition of the present invention. [(a) Urethane (Meth)acrylate] 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 by a known method.

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.

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-phenylenediisocyanate, p-phenylenediisocyanate, dicyclohexylmethane 4,4'-diisocyanate, 2 , 2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, and the allophanate polyisocyanate represented by the above formula [1] obtained by polymerizing these diisocyanates, the diurea polyisocyanate represented by the above formula [2], the adduct polyisocyanate represented by the above formula [3], and the isocyanurate polyisocyanate represented by the above formula [4].

In the above formulas [1] to [4], R ¹ , R ² , R ³ , and R ⁴ are groups formed by removing two isocyanate groups from the above diisocyanate, and an example of which is hexamethylene. In the above formula [1], R ⁰ is a group formed by removing an OH group from a monohydric alcohol that reacts with the above diisocyanate to form an amine ester bond. In the above formula [3], R ⁵ is a group formed by removing all OH groups from a dihydric alcohol, trihydric alcohol, or tetrahydric alcohol that reacts with the above diisocyanate to form an amine ester bond.

As (a) urethane (meth)acrylate, commercially available products can be used, for example, Artresin (registered trademark) UN-3320HA, Artresin UN-3320HC, Artresin UN-3320HS, Artresin UN-904, Artresin UN-906S, Artresin UN-901T, Artresin UN-905, Artresin UN-952 (all manufactured by Genjo Industries Co., 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, EBECRYL 8701, EBECRYL 4265, EBECRYL 46 66, EBECRYL1290, EBECRYL5129, KRM8667, KRM8200, KRM8200AE, KRM8530, KRM8904, KRM8531BA, KRM8452 (all manufactured by DAICEL-ALLNEX 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, and UA-122P (all manufactured by Shin-Nakamura Chemical Industry Co., Ltd.).

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

[(b) Silica Particles] 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 amine, amide, urea, thiourea, thiourethane, urea, and thiourea. Furthermore, the (b) silica particles, through interaction with the (a) urethane (meth)acrylate, impart stretchability without compromising scratch resistance.

The shape of the silica particles before their surfaces are modified with the silane coupling agent having the above-mentioned nitrogen-containing proton-donating groups (hereinafter referred to as "unmodified silica particles") is not particularly limited. For example, they may be approximately spherical particles or may be in an amorphous form such as a powder. Preferably, they are approximately spherical particles, more preferably approximately spherical particles with an aspect ratio of 1.5 or less, and most preferably, they are true spherical particles.

Furthermore, 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 60 nm to 250 nm, or 70 nm to 250 nm. The average particle size (nm) herein refers to the 50% volume diameter (median particle size) measured using the laser diffraction scattering method based on Mie theory. By ensuring that the average particle size of the silica particles (b) is within this numerical range, a cured film with excellent abrasion resistance can be obtained. Furthermore, the particle size distribution of the silica particles (b) is not particularly limited, but monodispersed particles with uniform particle size are preferred. Furthermore, the average particle size of the silica particles (b) is preferably selected so that the average particle size b/film thickness a = 0.01 to 1.0 relative to the film thickness of the cured film obtained from the curable composition of the present invention described below satisfies the ratio.

As unmodified silica particles, for example, colloidal silica having the aforementioned average particle size is preferably used. A silica sol can be used as the colloidal silica. Examples of the silica sol include aqueous silica sols produced by conventional methods using an aqueous sodium silicate solution as a raw material, and organic silica sols obtained by replacing the water serving as the dispersion medium of the aqueous silica sol with an organic solvent. Alternatively, a silica sol obtained by hydrolyzing and condensing an alkoxysilane such as methyl silicate or ethyl silicate in an organic solvent such as an alcohol in the presence of a catalyst (e.g., a basic catalyst such as ammonia, an organic amine compound, or sodium hydroxide) may be used, or an organosilicon sol obtained by replacing the solvent of the silica sol with another organic solvent may be used.

Examples of the organic solvent in the above-mentioned organosilicon 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; alcohols such as ethyl cellulose and ethylene glycol; and acetonitrile. The replacement of water, the dispersion medium of the aqueous silica sol, with an organic solvent, or the replacement with another desired organic solvent, can be carried out by conventional methods such as distillation and superfiltration. The viscosity of the organosilicon sol at 20° C. is, for example, 0.6 mPa·s to 100 mPa·s.

Examples of commercially available aqueous silica sols and organic silica sols include the SEAHOSTER (registered trademark) KE series [manufactured by Nippon Catalyst Co., Ltd.] and the SNOWTEX (registered trademark) series [manufactured by Nissan Chemical Co., Ltd.].

Examples of the nitrogen-containing proton-donating groups include amino groups, amido groups (-C(=O)NH- groups), ureidene groups (-NHC(=O)NH- groups), thioureidene groups (-NHC(=S)NH- groups), thiourethane groups (-NHC(=S)S- groups), urea groups (-NHC(=O)NH2 groups ₎ , and thiourea groups (-NHC(=S) _NH2 groups). Among these nitrogen-containing proton-donating groups, amino groups, ureidene groups, thioureidene groups, and urea groups are preferred. Considering the transparency of the cured film, ureidene groups, thioureidene groups, and urea groups are particularly preferred. The silane coupling agent used to modify the surface of unmodified silica particles may have at least one of the above-mentioned nitrogen-containing proton-donating groups, or may have multiple nitrogen-containing proton-donating groups.

(b) Silica particles can be prepared by mixing a silane coupling agent having a nitrogen-containing protogenic group with unmodified silica particles in the presence of water or an alcohol. The silane coupling agent having a nitrogen-containing protogenic group hydrolyzes to form silanol groups, which then undergo a condensation reaction with the silanol groups on the surface of the unmodified silica particles, forming bonds. This is believed to result in silica particles surface-modified with the silane coupling agent having a nitrogen-containing protogenic group. Specifically, for example, by mixing a colloidal solution of unmodified silica particles (silica sol) with a silane coupling agent having a nitrogen-containing proton-donating functional group, silica particles surface-modified with the silane coupling agent can be prepared. The colloidal solution and the silane coupling agent can be mixed at room temperature or while heating. From the perspective of reaction efficiency, mixing while heating is preferred. When mixing while heating, the heating temperature can be appropriately selected depending on the type of solvent. For example, the heating temperature can be set to above 30°C. The mixing ratio of the silane coupling agent having the aforementioned nitrogen-containing proton-donating functional group to the unmodified silica particles 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 such that the number of silane coupling agent molecules per unit surface area (1 ^nm2 ) of the unmodified silica particles is 0.01 to 5, preferably 0.05 to 2, and more preferably 0.1 to 1. The surface area of the unmodified silica particles is calculated based on the specific surface area measured by nitrogen adsorption (BET method).

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 singly or in combination of two or more.

[(c) Perfluoropolyether] In the curable composition of the present invention, the preferred perfluoropolyether (c) comprises a poly(oxyperfluoroalkylene) group having an active energy ray-polymerizable group at the end of the molecular chain via an urethane bond. The ends of the perfluoropolyether molecular chain may be all or a portion of the molecular chain. When the perfluoropolyether molecular chain is linear, all or a portion of the molecular chain may be both or a single terminus of the linear molecular chain, respectively. The linking group between the poly(oxyperfluoroalkylene) group and the urethane bond may be, for example, a alkyl group having an ether bond, wherein at least one hydrogen atom of the alkyl group may be substituted with a fluorine atom. In the curable composition of the present invention, the perfluoropolyether (c) functions as a surface modifier in the hardcoat layer formed therefrom. Furthermore, the perfluoropolyether (c) exhibits excellent compatibility with the urethane (meth)acrylate (a), thereby enabling the formation of a hardcoat layer with suppressed whitening and a transparent appearance.

From the perspective of obtaining a cured film with excellent abrasion resistance, the poly(oxyperfluoroalkylene) group preferably has two repeating units: -[ _CF₂O ]-(oxyperfluoromethylene) and -[ _CF₂CF₂O ]-( _{oxyperfluoroethylene} ). In this case, the oxyperfluoroalkylene groups may have either block or random bonding. The total number of repeating units in the oxyperfluoroalkylene group is preferably 5 to 30, more preferably 7 to 21.

The molecular chain containing the poly(oxyperfluoroalkylene) group preferably has a structure represented by the following formula [5]. In formula [5], n represents the total number of repeating units -[CF ₂ CF ₂ O]- and repeating units -[CF ₂ O]-, and is preferably an integer in the range of 5 to 30, more preferably an integer in the range of 7 to 21. Furthermore, the ratio of the number of repeating units -[CF ₂ CF ₂ O]- to the number of repeating units -[CF ₂ O]- is preferably in the range of 2:1 to 1:2, more preferably in the range of approximately 1:1. The bonding of these repeating units may be either block bonding or random bonding.

Examples of the active energy ray polymerizable groups include (meth)acryloyl and vinyl groups. (c) Perfluoropolyether is not limited to one having one active energy ray polymerizable group at the end of the molecular chain containing a poly(oxyperfluoroalkylene) group, but may also include one having 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 acryl group in these structures with a methacryloyl group. Among these structures, preferred are the structures of formula [A3], formula [A4], and formula [A5] having two or more active energy ray polymerizable groups, and structures obtained by replacing the acryl group in these structures with a methacryloyl group. [Chemistry 5]

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 (c) perfluoropolyether content to 0.05 parts by mass or greater, sufficient abrasion resistance can be imparted to the hard coat layer. Furthermore, by setting the (c) perfluoropolyether content to 10 parts by mass or less, sufficient compatibility with the (a) urethane (meth)acrylate is achieved, resulting in a less turbid hard coat layer.

Furthermore, the perfluoropolyether (c) may be used singly or in combination of two or more. When two or more are used in combination, the perfluoropolyether may contain a poly(oxyperfluoroalkylene) group having an active energy ray-polymerizable group at one end (one end) of a molecular chain containing a poly(oxyperfluoroalkylene) group via an urethane bond, and a hydroxyl group at the other end (the other end) of the molecular chain. Furthermore, the perfluoropolyether (c) may contain no poly(oxyalkylene) group between the poly(oxyperfluoroalkylene) group and the urethane bond, or between the poly(oxyperfluoroalkylene) group and the hydroxyl group.

[(d) Polymerization Initiator] Preferred polymerization initiators (d) in the curable composition of the present invention are those that generate free radicals upon exposure to active energy rays, such as electron beams, ultraviolet rays, or X-rays, particularly those that generate free radicals upon exposure to ultraviolet rays.

Examples of the polymerization initiator (d) include benzoins, phenanones, 9-oxosulfuron The polymerization initiator (d) may be a benzophenone, azo, azido, diazo, o-quinonediazide, acylphosphine oxide, oxime ester, organic peroxide, benzophenone, dicoumarin, bisimidazole, titanocene, thiol, alkyl halides, trichloromethyl triphosphonium, and onium salts such as iodonium salts and codonium salts. These polymerization initiators may be used alone or in combination. In the present invention, phenanones are preferably used as the polymerization initiator (d) from the perspectives of transparency, surface curability, and thin film curability. The use of phenanones can produce a cured film with even greater scratch resistance.

Examples of the phenanones 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-olinopropane-1-one and 2-benzyl-2-dimethylamino-1-(4-olinophenyl)butane-1-one; 2,2-dimethoxy-1,2-diphenylethane-1-one; and methyl phenylglyoxylate.

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

[(e) Antistatic Agent] The curable composition of the present invention may further contain an (e) antistatic agent as an optional component. Examples of the (e) antistatic agent include organic conductive polymers such as PEDOT/PSS (Poly(3,4-ethylenedioxythiophene)/Poly(styrenesulfonate) (see figure), poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonic acid) or metal oxide particles. The metal oxide particles may be microparticles with a primary particle size of 4 to 100 nm. By setting the primary particle size of the metal oxide particles within the above numerical range, antistatic properties can be imparted without affecting scratch resistance and elongation, and a cured film can be obtained that achieves transparency. In the present invention, the primary particle size of the metal oxide particles refers to the particle size of each particle observed using a transmission electron microscope.

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 (SnO ₂ ), 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). Among them, oxides of the above elements with dopants added are preferred as antistatic agents, and phosphorus-doped tin oxide (PTO) is particularly preferred.

Examples of the metal oxide particles include surface-coated metal oxide particles having a metal oxide core and a surface coated with an acidic or alkaline oxide. Examples of the core include, in addition to the above-mentioned metal oxide particles such as tin oxide, titanium oxide, a titanium oxide-tin oxide complex, a zirconium oxide-tin oxide complex, a tungsten oxide-tin oxide complex, and a titanium oxide-zirconia-tin oxide complex. Examples of the acidic or alkaline oxide include antimony pentoxide, a silicon oxide-antimony pentoxide complex, and a silicon oxide-tin oxide complex.

In the present invention, when an antistatic agent (e) is included, its content is preferably 10 to 100 parts by mass, and 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.

[(f) Solvent] The curable composition of the present invention may further contain a solvent (f) as an optional component, thereby forming a varnish. The solvent (f) should be appropriately selected by considering the solubility and dispersibility of the aforementioned components (a) to (d) and the optional component (e), as well as the workability during application of the curable composition to form the cured film (hard coat) described below, and the drying properties before and after curing.

Examples of the solvent (f) include aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and naphthalene; 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, methylcellol acetate, ethylcellol acetate, and propylene glycol monomethyl ether acetate (PGMEA); diethyl ether, tetrahydrofuran (THF), 1,4-dioxane, methylcellol, ethylcellol, butylcellol, propylene glycol monomethyl ether, 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, t-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 prepared by mixing two or more of these solvents.

Furthermore, when drying after applying the curable composition, a high boiling point solvent may be used to control the dispersibility of the silica particles (b) described above. Examples of such solvents include cyclohexyl acetate, propylene glycol diacetate, 1,3-butanediol 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.

In the curable composition of the present invention, the content of the solvent (f) is not particularly limited. For example, the solid content concentration of the curable composition of the present invention is 1% to 70% by mass, preferably 5% to 50% by mass. Here, the solid content concentration (also referred to as the non-volatile content concentration) refers to the content of the solid content (after removing the solvent from all components) relative to the total mass (total mass) of the above-mentioned components (a) to (d), as well as the optional component (e), the above-mentioned component (f), and other additives of the curable composition of the present invention.

[Other Additives] Additionally, the curable composition of the present invention may contain conventional additives such as polymerization inhibitors, photosensitizers, leveling agents, surfactants, adhesion enhancers, plasticizers, UV absorbers, storage stabilizers, inorganic fillers, pigments, dyes, etc., either alone or in combination, as long as the effects of the present invention are not impaired.

<Cured Film> The curable composition of the present invention is applied to a substrate to form a coating film. This coating film is then irradiated with active energy rays to polymerize (cure), thereby forming a cured film. This cured film is also the subject of the present invention. Furthermore, a hard coating layer in the hard coating film described below may include the aforementioned cured film.

Examples of the substrate include various resins (polycarbonate, polymethacrylate, polystyrene, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyurethane, thermoplastic polyurethane (TPU), polyolefin, polyamide, polyimide, epoxy resin, melamine resin, triacetyl cellulose (TAC), acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer (AS), and norethinyl resins), metal, wood, paper, glass, and slate. These substrates can be in the form of plates, films, or three-dimensional shapes. Furthermore, a primer layer, an ultraviolet absorption layer, an infrared absorption layer, a near-infrared absorption layer, an electromagnetic wave absorption layer, a color correction layer, a refractive index adjustment layer, a weather-resistant layer, an anti-reflection layer, an anti-static layer, an anti-discoloration layer, a gas barrier layer, a water vapor barrier layer, a light scattering layer, an electrode layer, etc. may be formed on the surface of the substrate as a base layer of the hard coat layer. Multiple layers of these base layers of the hard coat layer may be stacked. The layers formed on the surface of the substrate are not particularly limited as long as they do not impair the effects of the present invention.

Coating methods for the above-mentioned substrates can be appropriately selected from polishing, rotary coating, doctor blade coating, dip coating, roll coating, spray coating, rod coating, die coating, inkjet coating, and printing methods (such as letterpress printing, gravure printing, offset printing, and screen printing). Letterpress printing, particularly gravure coating, is preferred from the perspective of roll-to-roll and film coating suitability. Furthermore, it is preferred to filter the curable composition of the present invention using a filter with a pore size of approximately 0.2 μm before applying the composition. Furthermore, during coating, a solvent may be added to the curable composition as needed. Examples of the solvent in this case include the various solvents listed in [(f) Solvent] above.

After the curable composition of the present invention is applied to a substrate to form a coating, the coating is pre-dried using a heating mechanism such as a hot plate or oven to remove the solvent (a solvent removal step), if necessary. Heat drying conditions at this stage are preferably set at 40°C to 120°C for approximately 30 seconds to 10 minutes. After drying, the coating is cured by irradiation with active energy radiation, such as ultraviolet radiation. Examples of active energy radiation include ultraviolet radiation, electron beams, and X-rays, with ultraviolet radiation being particularly preferred. Examples of UV irradiation light sources include sunlight, chemical lamps, low-pressure mercury lamps, high-pressure mercury lamps, metal halogen lamps, xenon lamps, and UV-LEDs (Ultraviolet-Light-Emitting Diodes). Furthermore, a post-baking step may be performed, specifically using a heating mechanism such as a hot plate or oven, to complete polymerization.

Furthermore, the thickness of the formed cured film after drying and curing is generally 0.1 μm to 50 μm, preferably 0.5 μm to 20 μm.

<Hard Coat Film> The curable composition of the present invention can be used to produce a hard coat film having a hard coat layer on at least one 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.

The hard coat layer of the hard coat film of the present invention can be formed by the following method, which includes: applying the curable composition of the present invention to a film substrate to form the coating; optionally removing the solvent by heating; and irradiating the coating with active energy such as ultraviolet light to cure the coating. A method for manufacturing a hard coat film comprising these steps, in which a hard coat layer is formed on at least one surface of a film substrate, is also the subject of the present invention.

As the film substrate, films made from any of the transparent resins listed above for optical applications can be used. Preferred resin films include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), polyurethanes, thermoplastic polyurethanes (TPU), polycarbonates, polymethacrylates, polystyrenes, polyolefins, polyamides, polyimides, and triacetyl cellulose (TAC). The film substrate can be formed by laminating multiple layers. For example, a layer different from the resin film, such as a primer layer, an ultraviolet absorption layer, an infrared absorption layer, a near-infrared absorption layer, an electromagnetic wave absorption layer, a color correction layer, a refractive index adjustment layer, a weathering layer, an anti-reflection layer, an anti-static layer, an anti-discoloration layer, a gas barrier layer, a water vapor barrier layer, a light scattering layer, or an electrode layer, may be deposited on the surface of the resin film to serve as a base layer for the hard coat layer. Multiple base layers of the hard coat layer may also be deposited. The layer deposited on the surface of the resin film is not particularly limited as long as it does not impair the effects of the present invention.

Furthermore, the methods for applying the curable composition of the present invention to the aforementioned film substrate (film formation step) and irradiating the film with active energy rays (curing step) can employ the methods exemplified in the "Cured Film" section above. Furthermore, when the curable composition of the present invention contains a solvent (in the form of a varnish), the film formation step may optionally include a step of drying the film to remove the solvent. In this case, the film drying method (solvent removal step) exemplified in the "Cured Film" section above can be employed.

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

The present invention is further described below with reference to the following examples, but the present invention is not limited to the following examples. In addition, in the examples, the apparatus and conditions used for sample preparation and physical property analysis are as follows.

(1) Coating using a rod coater Device: PM-9050MC manufactured by SMT Co. Rod: A-Bar OSP-22 manufactured by OSG SYSTEM PRODUCTS Co., Ltd., maximum wet film thickness 22 μm (equivalent to wire rod coater #9) Coating speed: 4 m/min (2) Oven Equipment: 2-layer clean oven (upper and lower type) PO-250-45-D manufactured by Tri-Meter Co., Ltd. (3) UV curing Equipment: CV-110QC-G manufactured by Heraeus Co., Ltd. Lamp: H-bulb electrodeless lamp manufactured by Heraeus Co., Ltd. (4) Gel permeation chromatography (GPC) Equipment: HLC-8220GPC manufactured by Tosoh Co., Ltd. Column: Shodex (registered trademark) GPC K-804L, GPC K-805L manufactured by Showa Denko Co., Ltd. Column temperature: 40°C Eluent: Tetrahydrofuran Detector: RI (Refractive Index, refractive index) (5) Abrasion resistance test Equipment: TRIBOGEAR TYPE, manufactured by Shinto Science Co., Ltd.: 30S Scanning speed: 5,000 mm/min Scanning distance: 50 mm (6) Tensile test Equipment: Autograph AGS-10kNX, desktop precision universal testing machine manufactured by Shimadzu Corporation Clamp: 1 kN manual screw type flat clamp Grip tooth: High-strength rubber coating gripper Tension speed: 10 mm/min Measurement temperature: 23°C (7) Surface resistance measurement Equipment: Hiresta UP, high resistivity meter manufactured by Nitto Seiko ANALYTECH Co., Ltd. (formerly Mitsubishi Chemical ANALYTECH Co., Ltd.) MCP-HT450 Probe: URS probe Register table: UFL Applied voltage: 10 V

In addition, the abbreviations have the following meanings. Multifunctional acrylate having one hydroxyl group (a1-1): Dipentaerythritol pentaacrylate/hexaacrylate mixture [ARONIX (registered trademark) M-403 manufactured by Toagosei Co., Ltd., pentad ratio 50% to 60% (catalog value), estimated hydroxyl value = 63.3 mgKOH/g (calculated as 55% pentavalent and 45% hexavalent) Allophanate polyisocyanate (a2-1): Allophanate-modified hexamethylene diisocyanate [Duranate (registered trademark) A201H manufactured by Asahi Kasei Chemicals Co., Ltd., isocyanate group content = 17.2% by mass, difunctional] Biuret polyisocyanate (a2-2): Biuret-modified hexamethylene diisocyanate [Duranate (registered trademark) 24A-100 manufactured by Asahi Kasei Chemicals Co., Ltd., isocyanate group content = 23.5% by mass, trifunctional] Isocyanurate polyisocyanate (a2-3): Hexamethylene diisocyanate Isocyanurate-modified product [Duranate (registered trademark) TLA-100 manufactured by Asahi Kasei Chemicals Co., Ltd., isocyanate group content = 23.3% by mass, trifunctional] Adduct polyisocyanate (a2-4): Adduct-modified product of hexamethylene diisocyanate [Duranate (registered trademark) P301-75E manufactured by Asahi Kasei Chemicals Co., Ltd., isocyanate group content = 12.5% by mass, trifunctional] UA5: Urethane acrylate [Artresin (registered trademark) UN-904 manufactured by Negami Industries Co., Ltd. (number of functional groups: 10, weight-average molecular weight Mw: 4900)] Silica fine particles s-1: Average particle size 80 Silica particles with an average particle size of 200 nm [Nissan Chemical Co., Ltd., organosilicone sol MA-ST-ZL (30% solids, methanol dispersion)] Silica particles s-2: Silica particles with an average particle size of 200 nm [Nissan Chemical Co., Ltd., organosilicone sol MEK-ST-2040 (40% solids, methyl ethyl ketone dispersion)] Silica particles s-3: Average particle size 40 100 nm silica particles [Nissan Chemical Co., Ltd., organosilicon sol MA-ST-L (solids content 30% by mass, methanol dispersion)] Silane coupling agent Si-1: Trimethoxysilane with thiourea groups [Shin-Etsu Chemical Co., Ltd., X-12-1116] Silane coupling agent Si-2: Trimethoxysilane with urea groups [Shin-Etsu Chemical Co., Ltd., X-12989MS] Silane coupling agent Si-3: 3-Ureidopropyltriethoxysilane [Tokyo [Manufactured by Kasei Industries, solid content 50% by mass, alcohol solution] Silane coupling agent Si-4: Trimethoxysilane with a hexyl group [KBM-3063 manufactured by Shin-Etsu Chemical Co., Ltd.] Silane coupling agent Si-5: Trimethoxysilane with an acryl group [KBM-5103 manufactured by Shin-Etsu Chemical Co., Ltd.] PFPE: Perfluoropolyether having two hydroxyl groups at each end of the molecular chain containing a poly(oxyperfluoroalkylene) group, not through a poly(oxyalkylene) group [Solvay Fomblin (registered trademark) T4 manufactured by Specialty Polymers Co., Ltd. BEI: 1,1-Bis(acryloyloxymethyl)ethyl isocyanate [Karenz (registered trademark) BEI manufactured by Showa Denko Co., Ltd.] DOTDD: Dioctyltin dineodecanoate [NEOSTANN (registered trademark) U-830 manufactured by Nitto Kasei Co., Ltd.] SM2: Perfluoropolyether urethane acrylate having a total of four acryl groups at both ends of the molecular chain containing poly(oxyperfluoroalkylene) groups [Solvay Specialty Polymers Co., Ltd.] [FLUOROLINK (registered trademark) AD-1700 manufactured by Polymers, 70% non-volatile solution] SM3: Polydimethylsiloxane with a methacryloyl group at one end [Silaplane (registered trademark) FM-0721 manufactured by JNC Corporation] O2959: 2-Hydroxy-1-(4-(2-hydroxyethoxy)phenyl)-2-methylpropane-1-one [IGM OMNIRAD (registered trademark) 2959 manufactured by Resins Co., Ltd. MEK: Methyl Ethyl Ketone MeOH: Methanol Antistatic Agent e-1: 20% by mass of tin oxide phosphate dispersed in isopropyl alcohol [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] *Here, primary and secondary particle sizes refer to the average particle size measured by transmission electron microscopy. The particle size was determined by dropping the sol onto a copper grid under a transmission electron microscope (JEM-1020, manufactured by JEOL Ltd.) and drying it. The sol was then observed at an accelerating voltage of 100 kV. 100 particles were measured, and the average value was used as the average primary particle size. Antistatic Agent e-2: A 30% by mass methanol dispersion of core-shell particles with a primary particle size of 30 nm to 40 nm, consisting of a tin oxide core coated with antimony pentoxide [Celnax (registered trademark) HX-307M1, manufactured by Nissan Chemical Co., Ltd.].

[Preparation Example 1] Preparation of Surface Modifier SM1 To a spiral tube were added 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 combined mass of PFPE and BEI), and 1.67 g of MEK. The resulting mixture was stirred at room temperature (approximately 23°C) for 72 hours using a stirrer to obtain a 50% by mass solution of the target compound, surface modifier SM1, in MEK. The weight-average molecular weight (Mw) of the resulting SM1, as measured by GPC (polystyrene equivalent), was 3,000, and the dispersity (weight-average molecular weight (Mw)/number-average molecular weight (Mn)) was 1.2.

[Calculation Method for the Amount of Polyisocyanate Added in the Production of Urethane Acrylates] A multifunctional acrylate (a1-1) having one hydroxyl group is reacted with various polyisocyanates (a2-1) to (a2-4). The amount of polyisocyanate added to produce the urethane acrylate is calculated using [Hydroxy value of (a1-1) / 561] × (42 × 100 / Isocyanate group content) × [Amount of (a1-1) / 100] × (Number of NCO groups / Number of OH groups).

[Preparation Example 2] Preparation of Urethane Acrylate UA1: In a spiral tube, 10 g of (a1-1) and 2.76 g of the allophanate polyisocyanate (a2-1) were added so that the ratio of OH groups to NCO groups was 1. Furthermore, 0.13 g of DOTDD (0.01 times the combined mass of (a1-1) and (a2-1)) and 3.22 g of MEK were added. The resulting mixture was stirred at room temperature (approximately 23°C) with a stirrer until the infrared absorption spectrum at 2260 cm ^-1 , indicating isocyanate groups, disappeared. This yielded an 80% by mass MEK solution of the target urethane acrylate UA1.

[Preparation Example 3] Preparation of Urethane Acrylate UA2: In a spiral tube, 10 g of (a1-1) and 3.02 g of biurea polyisocyanate (a2-2) were added so that the ratio of OH groups to NCO groups was 2/3. Furthermore, 0.13 g of DOTDD (0.01 times the combined mass of (a1-1) and (a2-2)) and 2.96 g of MEK were added. The resulting mixture was stirred at room temperature (approximately 23°C) for approximately 3 hours using a stir bar. 0.33 g of MeOH was then added to eliminate residual isocyanate groups. The mixture was stirred at room temperature (approximately 23°C) until the infrared absorption spectrum at 2260 cm ^-1 , representing isocyanate groups, disappeared. This yielded an 80 wt% MEK/MeOH solution of the target compound, urethane acrylate UA2.

[Preparation Example 4] Preparation of Urethane Acrylate UA3: In a spiral tube, 10 g of (a1-1) and 3.05 g of the isocyanurate polyisocyanate (a2-3) were added so that the ratio of OH groups to NCO groups was 2/3. Furthermore, 0.13 g of DOTDD (0.01 times the combined mass of (a1-1) and (a2-3)) and 2.97 g of MEK were added. The resulting mixture was stirred at room temperature (approximately 23°C) for approximately 3 hours using a stir bar. 0.33 g of MeOH was then added to eliminate residual isocyanate groups. Stirring was continued at room temperature (approximately 23°C) until the infrared absorption spectrum at 2260 cm ^-1 , representing isocyanate groups, disappeared. This yielded an 80 wt% MEK/MeOH solution of the target compound, urethane acrylate UA3.

[Preparation Example 5] Preparation of Urethane Acrylate UA4: In a spiral tube, 10 g of (a1-1) and 3.73 g of the adduct polyisocyanate (a2-4) were added so that the ratio of OH groups to NCO groups was 1. Furthermore, 0.14 g of DOTDD (0.01 times the combined mass of (a1-1) and (a2-4)) and 3.47 g of MEK were added. The resulting mixture was stirred at room temperature (approximately 23°C) with a stir bar until the infrared absorption spectrum at 2260 cm ^-1 , indicating isocyanate groups, disappeared. This yielded an 80% by mass MEK solution of the target urethane acrylate UA4.

[Preparation Example 6] Preparation of Silica Particles S-4 Surface-Modified with a Silane Coupling Agent Having Thioureyl Groups To a four-necked flask, 35 g of silica particles S-1, 0.17 g of the silane coupling agent Si-1, and 0.18 g of water were added. The resulting mixture was stirred at 65°C for 3 hours using a stirring rod. This yielded a 30% by mass MeOH dispersion of the target compound, silica particles S-4, with an average particle size of 80 nm, surface-modified with a silane coupling agent having thiourea groups.

[Preparation Example 7] Preparation of Silica Particles S-5 Surface-Modified with a Silane Coupling Agent Having Urea Groups To a four-necked flask, 30 g of silica particles S-1, 0.15 g of the silane coupling agent Si-2, and 0.21 g of water were added. The resulting mixture was stirred at 65°C for 3 hours using a stirring rod. This yielded a 30% by mass MeOH dispersion of the target compound, silica particles S-5, with an average particle size of 80 nm, surface-modified with a silane coupling agent having urea groups.

[Preparation Example 8] Preparation of Silica Particles S-6 Surface-Modified with a Silane Coupling Agent Containing Urea Groups To a four-necked flask, 30 g of silica particles S-1, 0.27 g of the silane coupling agent Si-3, and 0.21 g of water were added. The resulting mixture was stirred at 65°C for 3 hours using a stirring rod to obtain a 30% by mass MeOH dispersion of the target compound, silica particles S-6, surface-modified with a silane coupling agent containing urea groups and having an average particle size of 80 nm.

[Preparation Example 9] Preparation of Silica Particles S-7 Surface-Modified with a Silane Coupling Agent Having Thioureyl Groups To a four-necked flask, 60 g of silica particles S-2, 0.16 g of silane coupling agent Si-1, and 0.55 g of water were added. The resulting mixture was stirred at 65°C for 3 hours using a stirring rod to obtain a 40% by mass MEK dispersion of the target compound, silica particles S-7, surface-modified with a silane coupling agent having thiourea groups and having an average particle size of 200 nm.

[Preparation Example 10] Preparation of Silica Particles S-8 Surface-Modified with a Silane Coupling Agent Having Thioureyl Groups To a four-necked flask, 35 g of silica particles S-3, 0.35 g of the silane coupling agent Si-1, and 0.18 g of water were added. The resulting mixture was stirred at 65°C for 3 hours using a stirring rod to obtain a 30% by mass MeOH dispersion of the target compound, silica particles S-8, modified with a silane coupling agent having thiourea groups and having an average particle size of 40 nm.

[Preparation Example 11] Preparation of Silica Particles S-9 Surface-Modified with a Silane Coupling Agent Containing Acryloyl Groups To a four-necked flask, 30 g of silica particles S-1, 0.12 g of silane coupling agent Si-5, and 0.21 g of water were added. The resulting mixture was stirred at 65°C for 3 hours using a stirrer to obtain a 30% by mass MeOH dispersion of the target compound, silica particles S-9, surface-modified with a silane coupling agent containing acrylic groups and having an average particle size of 80 nm.

[Preparation Example 12] Preparation of Silica Microparticles S-10 Surface-Modified with a Silane Coupling Agent Containing Hexyl Groups To a four-necked flask, 30 g of silica microparticles S-1, 0.11 g of silane coupling agent Si-4, and 0.21 g of water were added. The resulting mixture was stirred at 65°C for 3 hours using a stirring rod. This yielded a 30% by mass MeOH dispersion of the target compound, silica microparticles S-10, surface-modified with a silane coupling agent containing hexyl groups and having an average particle size of 80 nm.

[Examples 1-11, Comparative Examples 1-10] The components listed in Table 1 were mixed to prepare curable compositions having the solid content concentrations listed in Table 1. Here, solid content refers to components excluding the solvent and dispersion medium. In Table 1, [parts] represents [parts by mass], and [%] represents [% by mass]. Furthermore, the urethane acrylate, silica particles, and surface modifier in Table 1 represent the solid content, respectively.

[Table 1] Table 1 Amine acrylate Silicon dioxide particles surface modifier O2959 MEK Solid content concentration Name [share] Name [share] Name [share] [share] [share] [%] Example 1 UA1 100 s-4 11 SM1 0.2 3 120.0 40 Example 2 UA1 100 s-4 50 SM1 0.3 4 89.8 40 Example 3 UA1 100 s-5 50 SM1 0.3 4 89.8 40 Example 4 UA1 100 s-6 50 SM1 0.3 4 89.8 40 Example 5 UA1 100 s-7 50 SM1 0.3 4 131.6 40 Example 6 UA1 100 s-8 50 SM1 0.2 4 89.8 40 Example 7 UA1 100 s-4 50 SM2 0.2 4 89.9 40 Comparative example 1 UA1 100 ---- ---- SM1 0.2 3 128.9 40 Comparative example 2 UA1 100 s-1 50 SM1 0.3 4 89.8 40 Comparative example 3 UA1 100 s-9 50 SM1 0.3 4 89.8 40 Comparative example 4 UA1 100 s-10 50 SM1 0.3 4 89.8 40 Comparative example 5 UA1 100 s-4 50 SM3 0.2 3 88.8 40 Comparative example 6 UA1 100 ---- ---- ---- ---- 3 128.8 40 Example 8 UA2 100 s-4 50 SM1 0.3 4 89.8 40 Comparative example 7 UA2 100 ---- ---- SM1 0.2 3 128.9 40 Example 9 UA3 100 s-4 50 SM1 0.3 4 89.8 40 Comparative example 8 UA3 100 ---- ---- SM1 0.2 3 128.9 40 Example 10 UA4 100 s-4 50 SM1 0.3 4 89.8 40 Comparative example 9 UA4 100 ---- ---- SM1 0.2 3 128.9 40 Example 11 UA5 100 s-4 50 SM1 0.3 4 114.8 40 Comparative example 10 UA5 100 ---- ---- SM1 0.2 3 153.9 40

The curable composition was 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 primed with a bonding agent on both sides. This film was then dried in an 80°C oven for 3 minutes to remove the solvent. The resulting film was then exposed to UV light at an exposure dose of 300 mJ/ ^cm² under a nitrogen atmosphere to produce a hardcoat layer (cured film).

The homogeneity of each curable composition, as well as the abrasion resistance and elongation of the resulting hardcoat films, were evaluated. The evaluation procedure is shown below. The results are summarized in Table 2. [Composition Homogeneity] The appearance of the curable composition was visually inspected two hours after preparation and evaluated according to the following criteria. A: Clear solution (no suspended matter or sediment present) C: Both suspended matter and sediment present [Abrasion Resistance] The hardcoat surface of the resulting hardcoat film was rubbed 10 times with a reciprocating stroke of 60 mm using a steel wool [BONSTAR (registered trademark) #0000 (ultra-fine)] attached to a reciprocating abrasion tester, applying the loads listed in Table 2. The surface was then visually inspected for scratches within the 60 mm stroke, excluding a 5 mm width at both ends. The surface was evaluated according to the following criteria: A, B, and C. Furthermore, assuming actual use as a hardcoat, a minimum rating of B is required, with A being ideal. A: No scratches (0 scratches) B: Scratches present (1 to 4 scratches with a length of 1 mm to 9 mm) C: Scratches present (5 or more scratches with a length of 1 mm to 9 mm, or 1 or more scratches with a length of 1 cm or more) [Elongation] The hardcoat film was cut into rectangular specimens 60 mm long and 10 mm wide to prepare test pieces. The specimens were mounted on the jigs of a universal testing machine, gripping each end by 20 mm. Tensile tests were performed at 1% increments, with elongation (= (increase in jig distance) ÷ (jig distance) × 100) set to 4%, 5%, and 6%. After the tensile test, the hard coat films were visually inspected to determine the maximum elongation at which cracks did not form in the hard coat layer. Subsequently, hard coat films were prepared using the curable compositions (Comparative Examples 1, 7, 8, 9, and 10) after removing the silica particles. Using the elongation of these hard coat films as a standard (=100%), the elongation improvement rate was calculated. This value was used as the elongation and evaluated according to the following criteria: A, B, and C. Furthermore, assuming actual use as a hard coat, a minimum of B is required, with A being ideal. A: 125% or higher B: More than 100% but less than 125% C: 100% or lower

[Table 2] Table 2 Appearance of the composition Film thickness [μm] Scratch resistance Scalability Load: 400 g Load: 300 g Load: 200 g Example 1 A 4 C A A B Example 2 A 4 A A ---- A Example 3 A 4 A A ---- B Example 4 A 4 A A ---- B Example 5 A 4 A A ---- B Example 6 A 4 B A ---- B Example 7 A 4 A A --- A Comparative example 1 A 4 C B A standard Comparative example 2 A 4 C B B B Comparative example 3 A 4 A A ---- C Comparative example 4 A 4 C B ---- C Comparative example 5 C 4 ---- ---- ---- ---- Comparative example 6 A 4 ---- ---- C B Example 8 A 4 A A ---- A Comparative example 7 A 4 C B A standard Example 9 A 4 A A ---- A Comparative example 8 A 4 C B A standard Example 10 A 4 C B A A Comparative example 9 A 4 ---- ---- C standard Example 11 A 4 A ---- ---- A Comparative example 10 A 4 A ---- ---- standard

As shown in Table 1, the curable compositions of Examples 1 to 7 include: urethane acrylate UA1 having an allophanate structure; silica particles s-4, s-5, s-6, s-7, or s-8 having an average particle size of 40 nm, 80 nm, or 200 nm, the surface of which is modified with a silane coupling agent having a nitrogen-containing proton-donating functional group; and perfluoropolyether SM1 or SM2 having an acryloyl group at each end of the molecular chain, respectively, via an urethane bond, as a surface modifier. Furthermore, as shown in Table 2, the hard coating films having the hard coating layer obtained from the curable compositions of Examples 1 to 7 exhibited superior abrasion resistance and elongation compared to the hard coating film having the hard coating layer obtained from the curable composition of Comparative Example 1 to which no silica fine particles were added.

On the other hand, the curable composition of Comparative Example 2 included urethane acrylate UA1, unmodified silica particles s-1, and surface modifier SM1. The hardcoat film obtained from the curable composition of Comparative Example 2 exhibited inferior scratch resistance compared to the hardcoat films obtained from the curable compositions of Examples 1 to 7. The curable compositions of Examples 1 to 7 included urethane acrylate UA1; silica particles s-4, s-5, or s-6 whose surfaces were modified with a silane coupling agent having thiourea, urea, or urea groups; and surface modifier SM1 or SM2. The results suggest that the interaction between urethane acrylate UA1 and silica particles s-1 is weak.

Furthermore, the curable composition of Comparative Example 3 includes urethane acrylate UA1, silica 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 includes urethane acrylate UA1, silica particles s-10 surface-modified with a silane coupling agent having a hexyl group, and surface modifier SM1. The hardcoat film obtained with the curable composition of Comparative Example 3 exhibits a stronger interaction between urethane acrylate UA1 and silica particles s-9, resulting in excellent scratch resistance, but poor elongation. Furthermore, in the hard coat film having a hard coat layer obtained from the curable composition of Comparative Example 4, the interaction between the urethane acrylate UA1 and the silica particles s-10 was weak, resulting in poor abrasion resistance.

On the other hand, the curable composition of Comparative Example 5 includes urethane acrylate UA1; silica particles s-4 surface-modified with a silane coupling agent having thiourea groups; and polydimethylsiloxane SM3 having a methacrylic group at one end as a surface modifier. In the case of the curable composition of Comparative Example 5, 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 hardcoat film obtained with the curable composition of Comparative Example 6, which did not include silica particles and a surface modifier, exhibited poor abrasion resistance.

The hardcoat film having a hardcoat layer obtained from the curable composition of Example 8 exhibited superior abrasion resistance and elongation compared to the hardcoat film having a hardcoat layer obtained from the curable composition of Comparative Example 7. The curable composition of Example 8 included urethane acrylate UA2 having a biuret structure, silica particles s-4, and surface modifier SM1. The curable composition of Comparative Example 7 did not contain silica particles.

The hardcoat film having a hardcoat layer obtained from the curable composition of Example 9 exhibited superior abrasion resistance and elongation compared to the hardcoat film having a hardcoat layer obtained from the curable composition of Comparative Example 8. The curable composition of Example 9 included urethane acrylate UA3 having an isocyanurate structure, silica particles s-4, and surface modifier SM1. The curable composition of Comparative Example 8 did not contain silica particles.

The hardcoat film having a hardcoat layer obtained from the curable composition of Example 10 exhibited superior abrasion resistance and elongation compared to the hardcoat film having a hardcoat layer obtained from the curable composition of Comparative Example 9. The curable composition of Example 10 included urethane acrylate UA4 having an adduct structure, silica particles s-4, and surface modifier SM1. The curable composition of Comparative Example 9 did not contain silica particles.

Furthermore, the hard coat film having a hard coat layer obtained from the curable composition of Example 11 exhibited equally excellent scratch resistance and superior elongation compared to the hard coat film having a hard coat layer obtained from the curable composition of Comparative Example 10. The curable composition of Example 11 contained commercially available urethane acrylate UA5, silica particles s-4, and surface modifier SM1. The curable composition of Comparative Example 10 did not contain silica particles. These results suggest that regardless of the type of urethane acrylate, the addition of silica microparticles s-4 surface-modified with a silane coupling agent containing thiourea groups can improve both scratch resistance and elongation, which are in a trade-off relationship.

[Examples 12-14] The components listed in Table 3 were mixed to prepare curable compositions having the solid content concentrations listed in Table 3. Here, solid content refers to the components excluding the solvent and dispersion medium. In Table 3, [parts] represents [parts by mass], and [%] represents [% by mass]. Furthermore, the urethane acrylate, silica particles, surface modifier, and antistatic agent in Table 3 represent the solid content, respectively.

[Table 3] Table 3 Amine acrylate Silicon dioxide particles surface modifier O2959 antistatic agent MeOH Solid content concentration Name [share] Name [share] Name [share] [share] Name [share] [share] [%] Example 12 UA1 100 s-4 50 SM1 0.3 4 e-1 83 ---- 33 Example 13 UA1 100 s-4 50 SM1 0.3 4 e-2 83 105 35 Example 14 UA5 100 s-4 50 SM1 0.3 4 e-2 83 130 35

The 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 primed with a bonding agent on both sides. This film was then dried in a 60°C oven for 3 minutes to remove the solvent. The resulting film was then exposed to UV light at an exposure dose of 300 mJ/ ^cm² under a nitrogen atmosphere, producing a hard coat layer (cured film) with a thickness of approximately 4 μm.

The resulting hard coat films were evaluated for surface resistance in addition to the aforementioned [Abrasion Resistance] and [Elongation] evaluations. The surface resistance evaluation procedure is shown below. The results are shown in Table 4. [Surface Resistance] The hard coat film was placed with the hard coat surface facing upward on the recorder table of a high resistivity meter. The probe was pressed against the hard coat film (hard coat layer) for 10 seconds, and the surface resistance (Ω/□) was measured three times. The average value was used as the surface resistance (Ω/□).

[Table 4] Table 4 Film thickness [μm] Scratch resistance Scalability Surface resistance [Ω/□] Load: 400 g Load: 300 g Example 12 4 B A A 5×10 ⁹ Example 13 4 B B A 2×10 ¹⁰ Example 14 4 B A A 8×10 ¹⁰

As shown in Tables 3 and 4, the hardcoat films obtained from the curable compositions of Examples 12 to 14 using the antistatic agent e-1 or e-2 exhibited excellent abrasion resistance and elongation, and also had antistatic properties.

Claims (22)

A curable composition comprising: (a) 100 parts by weight of urethane (meth)acrylate; (b) 5 to 70 parts by weight 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 the group consisting of ureylene groups, thioureylene groups, urea groups, and thiourea groups; (c) 0.05 to 10 parts by weight of a perfluoropolyether, wherein the perfluoropolyether has an active energy ray polymerizable group at the end of a molecular chain containing a poly(oxyperfluoroalkylene) group; and (d) 1 to 20 parts by weight of a polymerization initiator, wherein the polymerization initiator generates free radicals by active energy rays; and The above-mentioned (a) amine (meth)acrylate is the 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. The curable composition of claim 1, 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], [Chemical 1] (In the above formula, R ¹ , R ² , R ³ and R ⁴ each represent a alkyl group having 4 to 12 carbon atoms, R ⁰ represents a residue of a monohydric alcohol, R ⁵ represents a alkyl group having 2 to 6 carbon atoms, and m represents 2, 3 or 4). The curable composition of claim 1, 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'], [Chemical 2] (In the above formula, R ¹ , R ² , R ³ and R ⁴ each represent a alkyl group having 4 to 12 carbon atoms, R ⁰ represents a residue of a monohydric alcohol, R ⁵ represents a alkyl group having 2 to 6 carbon atoms, and m represents 2, 3 or 4). The curable composition of any one of claims 1 to 3, wherein the (b) silica particles are formed by modifying the surface of silica microparticles having an average particle size of 40 nm to 500 nm using the silane coupling agent having the nitrogen-containing proton-donating group. The curable composition according to any one of claims 1 to 3, wherein the nitrogen-containing proton-donating group is at least one group selected from the group consisting of ureylene groups, thioureylene groups, and urea groups. The curable composition according to any one of claims 1 to 3, wherein the perfluoropolyether (c) has an active energy ray polymerizable group at the terminal of the molecular chain comprising the poly(oxyperfluoroalkylene) group via a urethane bond. The curable composition of any one of claims 1 to 3, wherein the perfluoropolyether (c) has at least two active energy ray-polymerizable groups at the terminal of the molecular chain comprising the poly(oxyperfluoroalkylene) group via a urethane bond. The curable composition of any one of claims 1 to 3, wherein the perfluoropolyether (c) has at least two active energy ray polymerizable groups at both ends of the molecular chain comprising the poly(oxyperfluoroalkylene) group, respectively, via urethane bonds. The curable composition of any one of claims 1 to 3, wherein the poly(oxyperfluoroalkylene) group of the perfluoropolyether (c) has repeating units -[CF ₂ O]- and/or repeating units -[CF ₂ CF ₂ O]-, and when having these two repeating units, the repeating units are linked by block bonding, random bonding, or both block bonding and random bonding. The curable composition of claim 9, wherein the molecular chain containing the poly(oxyperfluoroalkylene) group has a structure represented by the following formula [5], [Chemical 3] (In the above formula [5], n is the total number of the repeating units -[CF ₂ CF ₂ O]- and the repeating units -[CF ₂ O]-, and represents an integer of 5 to 30. The repeating units -[CF ₂ CF ₂ O]- and the repeating units -[CF ₂ O]- are bonded by block bonding, random bonding, or block bonding and random bonding). The curable composition of any one of claims 1 to 3, further comprising (e) an antistatic agent. The curable composition of claim 11, wherein the antistatic agent (e) comprises metal oxide particles. The hardenable composition of claim 12, wherein the metal oxide particles comprise an oxide of at least one element selected from the group consisting of tin, zinc, and indium. The hardenable composition of claim 13, wherein the metal oxide particles comprise tin oxide to which a dopant may be added. The hardenable composition of claim 12, wherein the metal oxide particles comprise at least one of phosphorus-doped tin oxide and tin oxide surface-coated with antimony pentoxide. The hardenable composition of any one of claims 1 to 3, further comprising (f) a solvent. A cured film obtained from the curable composition according to any one of claims 1 to 16. A hard coating film is provided, wherein a hard coating layer is provided on at least one surface of a film substrate, and the hard coating layer comprises the cured film according to claim 17. A hard coat film is provided with a hard coat layer on at least one surface of a film substrate, wherein the hard coat layer is formed by the following method, the method comprising: applying a curable composition according to any one of claims 1 to 16 on the film substrate to form a coating film; and irradiating the coating film with active energy rays to cure the coating film. A hard coat film is provided with a hard coat layer on at least one side of a film substrate, wherein the hard coat layer is formed by the following method, which includes: applying the curable composition as claimed in claim 16 on the film substrate to form a coating film; removing the above-mentioned solvent from the coating film by heating; and irradiating the coating film with active energy rays to harden it. The hard coating film according to any one of claims 18 to 20, wherein the hard coating layer has a film thickness of 1 μm to 20 μm. A method for producing a laminate, comprising: applying the curable composition according to any one of claims 1 to 16 on a film substrate to form a coating; and irradiating the coating with active energy rays to cure the coating.