Composition for forming hard coat layer and hard coat film

Abstract

This composition for forming a hard coat layer contains: a compound (A) having one or two ethylenically unsaturated groups, a viscosity of 1-30 mPa·s at 25°C, and a boiling point of 200°C or higher at an atmospheric pressure of 1 atm; a compound (B) having three or more ethylenically unsaturated groups; inorganic fine particles (C); and a photopolymerization initiator (D). The mass ratio (A / B) of the compound (A) to the compound (B) is 30 / 70-80 / 20, and the content ratio of the solvent is 1 mass% or less in 100 mass% of the composition for forming a hard coat layer.

Description

Hard coat layer-forming composition and hard coat film

[0001] The present disclosure relates to a composition for forming a hard coat layer and a hard coat film.

[0002] Compositions for forming hard coat layers (hereinafter referred to as "hard coat agents") are required to protect the surfaces of various substrates with scratch resistance, stain resistance, abrasion resistance, flexibility, transparency, and the ability to prevent sticking (anti-blocking) when a film coated with the hard coat agent is wound into a roll. Various hard coat agents have been proposed depending on the application. Meanwhile, in recent years, there has been a growing trend both domestically and internationally to reduce and eliminate volatile organic compounds (hereinafter abbreviated as "VOCs") from the perspectives of environmental conservation and safety. Environmentally friendly hard coat agents that minimize volatile components such as organic solvents have become increasingly popular. Compared to conventional solvent-containing hard coat agents, environmentally friendly hard coat agents that minimize VOCs such as organic solvents have almost no odor, health hazards, or flammability, and do not require a thermal drying oven to volatilize the organic solvent, thereby resolving environmental, safety, and energy issues. However, environmentally friendly hard coating agents that minimize VOCs tend to have higher viscosity because they drastically reduce the amount of low-viscosity organic solvents, plasticizers, etc., making it difficult to apply a thin, uniform hard coating layer. Also, from the viewpoint of coating, if the amount of low-viscosity VOCs is increased, depending on the drying conditions, VOCs remain, making it impossible to solve the problem of scratches on the coating after curing.

[0003] Patent Document 1 proposes a cured film for hard coating that contains a multifunctional urethane acrylate, a di- or higher functional acrylate, and a monofunctional acrylate compound, and that is solvent-free and has excellent coating properties with a viscosity of 400 to 1200 mPa·s, forms a coating film that is high in hardness and scratch resistance and has excellent adhesion to the substrate, has small warpage resistance, and is excellent in chemical resistance.

[0004] International Publication No. 2009 / 050957

[0005] However, the curable composition for hard coating described in Patent Document 1 is difficult to control the film thickness at a thinner thickness and to form a smooth coating film, and the cured film also has problems with anti-blocking properties, which are necessary for stable processing when winding up a film coated with a hard coating agent and in subsequent secondary processing.The present disclosure aims to provide a composition for forming a hard coating layer, which has excellent coatability and is capable of forming a hard coating layer that combines transparency, anti-blocking properties, anti-fouling properties, scratch resistance, and curability, and a hard coating film having the hard coating layer.

[0006] The hard coat layer-forming composition and hard coat film according to the present disclosure have the following configurations [1] to [7]: [1] A hard coat layer-forming composition comprising: a compound (A) having one or two ethylenically unsaturated groups, a viscosity at 25°C of 1 to 30 mPa·s, and a boiling point at 1 atmosphere of 200°C or higher; a compound (B) having three or more ethylenically unsaturated groups; inorganic fine particles (C); and a photopolymerization initiator (D), wherein the mass ratio (A / B) of the compound (A) to the compound (B) is 30 / 70 to 80 / 20; and the content of the solvent is 1% by mass or less relative to 100% by mass of the hard coat layer-forming composition. [2] The hard coat layer-forming composition according to [1], wherein the content of compound (a1) having two ethylenically unsaturated groups, a viscosity at 25°C of 1 mPa·s or more but less than 6 mPa·s, and a boiling point at 1 atmosphere of 240°C or more is 70% by mass or more relative to 100% by mass of compound (A). [3] The hard coat layer-forming composition according to [1] or [2], wherein the inorganic fine particles (C) are contained in an amount of 1.0 part by mass or more but less than 10 parts by mass relative to 100 parts by mass of the total of compound (A) and compound (B). [4] The hard coat layer-forming composition according to any one of [1] to [3], wherein the inorganic fine particles (C) have an average dispersed particle diameter (D50) of 20 to 400 nm in the hard coat layer-forming composition. [5] The hard coat layer-forming composition according to any one of [1] to [4], wherein the inorganic fine particles (C) are silica fine particles. [6] The composition for forming a hard coat layer according to any one of [1] to [5], which has a viscosity of 20 to 120 mPa·s at 25° C. [7] A hard coat film having a light-transmitting substrate and a hard coat layer, wherein the hard coat layer is a cured product of the composition for forming a hard coat layer according to any one of [1] to [6].

[0007] The present disclosure can provide a composition for forming a hard coat layer, which has excellent coatability and is capable of forming a hard coat layer that combines transparency, anti-blocking properties, anti-fouling properties, scratch resistance, and curability, and a hard coat film having the hard coat layer.

[0008] Several embodiments of the present disclosure are described below. Note that the present disclosure is not limited to the examples in the following embodiments. In the present disclosure, unless otherwise specified, the terms "(meth)acrylate" and "(meth)acryloyl" mean "acrylate or methacrylate" and "acryloyl or methacryloyl," respectively. Furthermore, compound (A) having one or two ethylenically unsaturated groups, a viscosity at 25°C of 1 to 30 mPa·s, and a boiling point at 1 atmosphere of 200°C or higher may be abbreviated as "compound (A)," and compound (B) having three or more ethylenically unsaturated groups may be abbreviated as "compound (B)."

[0009] In this disclosure, unless otherwise specified, a numerical range specified using "to" includes the numerical values ​​before and after "to" as the range's lower and upper limits.

[0010] <<Hard Coat Layer-Forming Composition>> The hard coat layer-forming composition of the present disclosure contains a compound (A) having one or two ethylenically unsaturated groups, a viscosity at 25°C of 1 to 30 mPa·s, and a boiling point at 1 atmosphere of 200°C or higher, a compound (B) having three or more ethylenically unsaturated groups, inorganic fine particles (C), and a photopolymerization initiator (D), wherein the mass ratio (A / B) of the compound (A) to the compound (B) is 30 / 70 to 80 / 20, and the content of the solvent is 1.0 mass% or less relative to 100 mass% of the hard coat layer-forming composition.

[0011] The viscosity of the hard coat layer-forming composition at 25°C is preferably 20 to 120 mPa·s, more preferably 20 to 60 mPa·s. When the viscosity at 25°C is within this range, a uniform coating film is easily formed during coating, and the film thickness can be easily controlled to a predetermined value. In the present disclosure, the viscosity is measured using a cone-plate E-type viscometer. Details of the measurement method are described in the Examples.

[0012] [Compound (A)] Compound (A) is a compound having a viscosity of 1 to 30 mPa·s at 25°C, a boiling point at 1 atmosphere of 200°C or higher, and one or two ethylenically unsaturated groups. The use of compound (A) allows the viscosity of the curable composition to be reduced while minimizing the use of volatile components (organic solvents). The viscosity may be 1 mPa or higher but less than 6 mPa·s, or 6 mPa or higher but less than 30 mPa·s. In this disclosure, the viscosity is measured using a cone-plate E-type viscometer. Details of the measurement method are described in the Examples. The lower the viscosity, the better the coating properties, such as the smoothness of the coating film and its wettability to the substrate, but selecting a material solely from the perspective of low viscosity can result in a molecular weight that is too low or high volatility. Therefore, from the perspectives of coating suitability, such as viscosity, as well as safety and coating performance, compound (A) is specified to have a boiling point at 1 atmosphere of 200°C or higher.

[0013] In the film forming method of the present disclosure, a waiting step (described below) is performed from coating to curing with ultraviolet light or the like in order for the liquid curable composition disposed on the substrate to form a substantially continuous, stable liquid film. From the viewpoints of odor, safety, and coating film performance during the waiting step, the boiling point of the compound (A) at normal pressure is preferably 240°C or higher. A compound (A) with low volatility tends to be advantageous for the film formation. The boiling point of the compound (A) at normal pressure may be 200 to 240°C.

[0014] From the viewpoint of the hard coat layer's functions such as scratch resistance, the number of ethylenically unsaturated groups in the compound (A) is preferably 2. From the viewpoint of achieving both coatability such as viscosity and the hard coat layer's functions, a compound having two ethylenically unsaturated groups and a compound having one ethylenically unsaturated group can also be used in combination.

[0015] Compound (A) having one or two ethylenically unsaturated groups, a viscosity at 25°C of 1 to 30 mPa·s, and a boiling point at 1 atmosphere of 200°C or higher is selected from the group consisting of: compound (a1) having two ethylenically unsaturated groups, a viscosity at 25°C of 1 mPa·s or higher but less than 6 mPa·s, and a boiling point at 1 atmosphere of 240°C or higher; compound (a2) having one ethylenically unsaturated group, a viscosity at 25°C of 1 mPa·s or higher but less than 6 mPa·s, and a boiling point at 1 atmosphere of 240°C or higher; compound (a3) ​​having two ethylenically unsaturated groups, a viscosity at 25°C of 1 mPa·s or higher but less than 6 mPa·s, and a boiling point at 1 atmosphere of 200°C or higher but less than 240°C; Compounds (a4) have one ethylenically unsaturated group, a viscosity of 1 mPa s or more but less than 6 mPa s at 25°C, and a boiling point at 1 atmosphere of 200°C or more but less than 240°C; compounds (a5) have two ethylenically unsaturated groups, a viscosity of 6 to 30 mPa s at 25°C, and a boiling point at 1 atmosphere of 200°C or more but less than 240°C; compounds (a6) have one ethylenically unsaturated group, a viscosity of 6 to 30 mPa s at 25°C, and a boiling point at 1 atmosphere of 200°C or more but less than 240°C; compounds (a7) have two ethylenically unsaturated groups, a viscosity of 6 to 30 mPa s at 25°C, and a boiling point at 1 atmosphere of 240°C or more; and compounds (a8) have one ethylenically unsaturated group, a viscosity of 6 to 30 mPa s at 25°C, and a boiling point at 1 atmosphere of 240°C or more.

[0016] The boiling point at 1 atmospheric pressure can be determined from the reduced pressure boiling point in a catalog or the boiling point conversion chart described in Science of Petroleum, Vol. II, p. 1281 (1938).

[0017] Examples of the compound (a1) having two ethylenically unsaturated groups, a viscosity at 25°C of 1 mPa·s or more but less than 6 mPa·s, and a boiling point at 1 pressure of 240°C or more include 2-(2-vinyloxyethoxy)ethyl acrylate (a1-1) (boiling point: 246°C / 760 mmHg, viscosity: 3.65 mPa·s / 25°C), 2-(2-vinyloxyethoxy)ethyl methacrylate (a1-2) (boiling point: 257°C / 760 mmHg, viscosity: 3.19 mPa·s / 25°C), 1,4-butanediol diacrylate (a1-3) (boiling point: 284°C / 760 mmHg, viscosity: 5 mPa·s / 25°C), Examples include neopentyl glycol dimethacrylate (boiling point: 275°C / 760mmHg, viscosity: 5mPa·s / 25°C), 1,4-butanediol diacrylate (boiling point: 284°C / 760mmHg, viscosity: 5mPa·s / 25°C), diethylene glycol dimethacrylate (boiling point: 310°C / 760mmHg, viscosity: 5mPa·s / 25°C), and 1,6-hexanediol diacrylate (boiling point: 329°C / 760mmHg, viscosity: 5.5mPa·s / 25°C).

[0018] Examples of the compound (a2) having one ethylenically unsaturated group, a viscosity at 25°C of 1 mPa·s or more and 6 mPa·s or less, and a boiling point at 1 atmosphere of 240°C or more include isooctyl acrylate (boiling point: 243°C / 760mmHg, viscosity: 5mPa·s / 25°C), benzyl acrylate (boiling point: 249°C / 760mmHg, viscosity: 2.68mPa·s / 25°C), ethyl carbitol acrylate (ethoxyethoxyethyl acrylate) (boiling point: 250°C / 760mmHg, viscosity: 2.9mPa·s / 25°C), isodecyl acrylate (boiling point: 255°C / 760mmHg, viscosity: 5mPa·s / 25°C), Examples of the acrylate include isodecyl methacrylate (boiling point: 277°C / 760mmHg, viscosity: 5mPa·s / 25°C), n-octyl acrylate (boiling point: 279°C / 760mmHg, viscosity: 2mPa·s / 25°C), n-dodecyl methacrylate (lauryl methacrylate) (a2-1) (boiling point: 309°C / 760mmHg, viscosity: 4mPa·s / 25°C), and n-dodecyl acrylate (lauryl acrylate) (boiling point: 313°C / 760mmHg, viscosity: 5mPa·s / 25°C).

[0019] Examples of the compound (a3) ​​having two ethylenically unsaturated groups, a viscosity at 25°C of 1 mPa s or more and less than 6 mPa s, and a boiling point at 1 atmosphere of 200°C or more and less than 240°C include ethylene glycol dimethacrylate (a3-1) (boiling point: 235°C / 760 mmHg, viscosity: 3 mPa s / 25°C).

[0020] Examples of the compound (a4) having one ethylenically unsaturated group, a viscosity at 25°C of 1 mPa s or more and less than 6 mPa s, and a boiling point at 1 atmosphere of 200°C or more and less than 240°C include isononyl acrylate (a4-1) (boiling point: 227°C / 760 mmHg, viscosity: 2 mPa s / 25°C) and n-nonyl acrylate (boiling point: 239°C / 760 mHg, viscosity: 2 mPa s / 25°C).

[0021] Examples of the compound (a5) having two ethylenically unsaturated groups, a viscosity at 25°C of 6 to 30 mPa s, and a boiling point at 1 atmosphere of 200°C or higher and lower than 240°C include ethylene glycol diacrylate (a5-1) (boiling point: 231.8°C / 760 mmHg, viscosity: 14 mPa s / 25°C).

[0022] Examples of the compound (a6) having one ethylenically unsaturated group, a viscosity at 25°C of 6 to 30 mPa s, and a boiling point at 1 atmosphere of 200°C or higher and lower than 240°C include 2-ethylhexyl diglycol acrylate (a6-1) (boiling point: 213°C / 760 mmHg, viscosity: 7 mPa s / 25°C).

[0023] Examples of the compound (a7) having two ethylenically unsaturated groups, a viscosity at 25°C of 6 to 30 mPa·s, and a boiling point at 1 atmosphere of 240°C or higher include dicyclopentenyl acrylate (boiling point: 258°C / 760 mmHg, viscosity: 9 mPa·s / 25°C), neopentyl glycol diacrylate (boiling point: 281°C / 760 mmHg, viscosity: 6.5 mPa·s / 25°C), 1,4-butanediol dimethacrylate (boiling point: 284°C / 760 mHg, viscosity: 7 mPa·s / 25°C), 3-methyl-1,5-pentanediol diacrylate (boiling point: 289°C / 760 mmHg, viscosity: 8 mPa·s / 25°C), 1,3-butylene glycol dimethacrylate (boiling point: 290°C / 760mmHg, viscosity: 7mPa·s / 25°C), 1,3-butylene glycol diacrylate (boiling point: 290°C / 760mmHg, viscosity: 8mPa·s / 25°C), dicyclopentenyloxyethyl acrylate (boiling point: 298°C / 760mmHg, viscosity: 20mPa·s / 25°C), dipropylene glycol diacrylate (boiling point: 313°C / 760mmHg, viscosity: 8mPa·s / 25°C), dicyclopentenyloxyethyl methacrylate (boiling point: 314°C / 760mmHg, viscosity: 17.5mPa·s / 25°C), 1,6-hexanediol dimethacrylate (boiling point: 315°C / 760mmHg, viscosity: 6mPa·s / 25°C), 1,6-hexanediol acrylic acid polymer ester (boiling point: 329°C / 760mmHg, viscosity: 6mPa·s / 25°C), triethylene glycol dimethacrylate (boiling point: 337°C / 760mHg, viscosity: 9mPa·s / 25°C), 1,9-nonanediol diacrylate (boiling point: 342°C / 760mmHg, viscosity: 8mPa·s / 25°C), triethylene glycol diacrylate (boiling point: 354°C / 760mmHg, viscosity: 9.5mPa·s / 25°C), tripropylene glycol diacrylate (a7-1) (boiling point: 362°C / 760mmHg, viscosity: 14mPa·s / 25°C), Examples include tetraethylene glycol diacrylate (boiling point: 363°C / 760 mmHg, viscosity: 11 mPa·s / 25°C) and 1,9-nonanediol dimethacrylate (boiling point: 372°C / 760 mHg, viscosity: 8 mPa·s / 25°C).

[0024] Compounds (a8) having one ethylenically unsaturated group, a viscosity at 25°C of 6 to 30 mPa·s, and a boiling point at 1 atmosphere of 240°C or higher include 2-(2-ethoxyethoxy)ethyl acrylate (boiling point: 250°C / 760 mmHg, viscosity: 6 mPa·s / 25°C), isobornyl acrylate (boiling point: 254°C / 760 mHg, viscosity: 7.7 mPa·s / 25°C) (a8-1), isobornyl methacrylate (boiling point: 255°C / 760 mHg, viscosity: 6 mPa·s / 25°C), phenoxyethyl methacrylate (boiling point: 260°C / 760 mHg, viscosity: 7 mPa·s / 25°C), dicyclopentanyl acrylate (boiling point: 278°C / 760 mHg, viscosity: 12 mPa·s / 25°C), Dicyclopentanyl methacrylate (boiling point: 284°C / 760mHg, viscosity: 12mPa·s / 25°C), n-tridecyl acrylate (boiling point: 291°C / 760mHg, viscosity: 7mPa·s / 25°C), phenoxyethyl acrylate (boiling point: 293°C / 760mHg, viscosity: 9mPa·s / 25°C), phenoxydiethylene glycol acrylate (boiling point: 293°C / 760mHg, viscosity: 16mPa·s / 25°C), isostearyl acrylate (boiling point: 313°C / 760mHg, viscosity: 17mPa·s / 25°C), n-stearyl methacrylate (boiling point: 380°C / 760mHg, viscosity: 11mPa·s / 25°C), and Examples include n-stearyl acrylate (boiling point: 403°C / 760 mHg, viscosity: 8.5 mPa·s / 25°C).

[0025] The above-exemplified compounds (A) may be used alone or in combination of two or more. From the viewpoints of physical properties such as low viscosity, odor, safety, and curability, it is preferable to contain compounds (a1) and (a2) alone or in combination, and from the viewpoint of scratch prevention, it is more preferable to contain compound (a1). Among compounds (a1), from the viewpoint of achieving both hard coat layer function and coatability such as viscosity, 2-(2-vinyloxyethoxy)ethyl acrylate and 2-(2-vinyloxyethoxy)ethyl methacrylate, which have a viscosity of 4 mPa·s or less at 25°C, are preferred, with 2-(2-vinyloxyethoxy)ethyl acrylate being particularly preferred. These compounds are highly effective as reactive diluents with low viscosity, and by containing two types of ethylenically unsaturated groups, a radically polymerizable acryloyl group and a cationically polymerizable vinyl ether group, they are characterized by their resistance to oxygen inhibition and high reactivity, which tend to improve physical properties such as curability and scratch resistance.

[0026] From the viewpoint of achieving low viscosity, odor, safety, and scratch resistance, the content of compound (a1) in 100% by mass of compound (A) is preferably 70% by mass or more, and from the viewpoint of improving coatability, 75% by mass or more is more preferable. By including a large amount, the coating film strength is improved and a coating film that can withstand scratch resistance can be formed. From the viewpoint of cure shrinkage, the content of compound (a1) in 100% by mass of compound (A) may be 100% by mass, but is preferably less than 100% by mass. In addition to compound (a1), at least one of compounds (a2) to (a7) may be included in 100% by mass of compound (A).

[0027] [Compound (B)] Compound (B) is a compound having three or more ethylenically unsaturated groups. Examples of compound (B) include pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, caprolactone-modified tris(acryloxyethyl)isocyanurate, trimethylolethane tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, ... ester compounds of polyhydric alcohols and (meth)acrylic acid, such as acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, alkyl-modified dipentaerythritol tri(meth)acrylate, alkyl-modified dipentaerythritol tetra(meth)acrylate, alkyl-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and 1,2,3-cyclohexane tetra(meth)acrylate; Polyfunctional poly(meth)acrylate compounds such as polyurethane poly(meth)acrylate, polyester poly(meth)acrylate, polyether poly(meth)acrylate, polyacryl poly(meth)acrylate, polyalkyd poly(meth)acrylate, polyepoxy poly(meth)acrylate, polyspiroacetal poly(meth)acrylate, polybutadiene poly(meth)acrylate, polythiol polyene poly(meth)acrylate, and polysilicon poly(meth)acrylate; ester compounds synthesized from polyhydric alcohols, polybasic acids, and (meth)acrylic acid, such as ester compounds synthesized from trimethylolethane / succinic acid / acrylic acid=2 / 1 / 4 (molar ratio). These specific examples may be used alone or in combination of two or more.

[0028] From the viewpoints of adhesion and scratch resistance, the compound (B) is preferably dipentaerythritol pentaacrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, polyurethane poly(meth)acrylate, polyester poly(meth)acrylate, polyether poly(meth)acrylate, or polyacrylic poly(meth)acrylate, and pentaerythritol tri(meth)acrylate is particularly preferred. ) acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, polyurethane poly(meth)acrylate, and polyester poly(meth)acrylate are preferred, and further, from the viewpoint of viscosity adjustment, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate (b1), pentaerythritol triacrylate, pentaerythritol tetraacrylate (b2), and trimethylolpropane triacrylate (b3) are more preferred.

[0029] The mass ratio (A / B) of compound (A) to compound (B) is 30 / 70 to 80 / 20. This range further improves the coating film strength without increasing the viscosity, and enables the formation of a coating film that has sufficient adhesion to the substrate and scratch resistance. From the viewpoint of further improving coatability, a ratio of 35 / 65 to 65 / 35 is more preferable.

[0030] [Inorganic fine particles (C)] The inorganic fine particles (C) mainly play a role in imparting anti-blocking properties. The shape of the inorganic fine particles (C) is not limited, and for example, spherical, crushed, fibrous, irregular, etc. can be used.

[0031] Examples of inorganic fine particles (C) include metal oxide fine particles, metal hydroxide fine particles, glass fine particles, simple metal fine particles, carbon material fine particles, etc., and specific examples include silica, alumina, aluminum hydroxide, chromium oxide, iron oxide, zirconium oxide, zinc oxide, titanium oxide, barium sulfate, magnesium oxide, glass beads, titanium, carbon black, graphene, graphite, and diamond fine particles. These specific examples may be used alone or in combination of two or more. Inorganic fine particles (C) are preferably inorganic oxide fine particles, and silica fine particles are more preferred from the viewpoint of anti-blocking properties. The primary particle diameter of the inorganic fine particles (C) may be 500 nm or less, 400 nm or less, or 300 nm or less.

[0032] The surfaces of the inorganic fine particles (C) may be subjected to a surface treatment containing an organic compound. Reactive inorganic fine particles may also be used. Reactive inorganic fine particles are obtained by surface-modifying inorganic fine particles with a compound having a reactive group. Reactive inorganic fine particles are inorganic fine particles that react upon heating or exposure to active energy rays. Examples of reactive inorganic fine particles include particles having reactive groups such as polymerizable vinyl groups, ethylenically unsaturated groups such as (meth)acryloyl groups, and epoxy groups on the particle surface. Examples of surface treatment agents that can be used include silane coupling agents such as 3-(meth)acryloxypropyltrimethoxysilane, β-ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, hexamethyldisilazane, and dimethyldichlorosilane; and known treatment agents such as silicone oil.

[0033] The average dispersed particle diameter (D50) of the inorganic fine particles (C) in the composition for forming a hard coat layer is preferably 20 to 400 nm, more preferably 100 to 300 nm. This range is preferable because it allows the formation of a coating film that has both transparency (low haze) and anti-blocking properties. Furthermore, the primary particle diameter to obtain the above dispersed particle diameter is preferably 10 to 200 nm, more preferably 20 to 150 nm.

[0034] In the present disclosure, the average dispersed particle diameter (D50) of inorganic fine particles (C) in a composition for forming a hard coat layer refers to the volume-based average particle diameter (median diameter = D50) of inorganic fine particles (C) when the composition for forming a hard coat layer is measured using a Microtrac-Bell "UPA150-EX." Furthermore, the primary particle diameter is the average particle diameter of solid particles, which are the smallest particle unit and have boundaries between particles that are recognized as not being further divided, and is usually determined using transmission electron microscope images, etc. One example of a method for measuring the primary particle diameter is to measure the major axes of a significant number of inorganic fine particles (C) within the viewing angle using a transmission electron microscope, and then calculate the arithmetic average value. Details of the method for measuring the dispersed particle diameter of inorganic fine particles (C) in a composition for forming a hard coat layer are described in the Examples section.

[0035] The content of the inorganic fine particles (C) is preferably 1.0 part by mass or more and less than 10 parts by mass, more preferably 2.5 to 4.5 parts by mass, relative to 100 parts by mass of the total of the compound (A) and the compound (B). By including the inorganic fine particles (C) in the range of 1.0 part by mass or more and less than 10 parts by mass, a composition for forming a hard coat layer having improved transparency and smoothness and excellent anti-blocking properties can be obtained.

[0036] Pre-dispersing the inorganic fine particles (C) in the compound (A) tends to stabilize the viscosity of the hard coat-forming composition, thereby improving the coatability, transparency, and smoothness, and providing a hard coat-forming composition with excellent anti-blocking properties.

[0037] [Photopolymerization Initiator (D)] The photopolymerization initiator (D) is not particularly limited as long as it has the function of initiating radical polymerization upon photoexcitation, and examples thereof include acetophenone compounds, benzoin compounds, benzophenone compounds, phosphine oxide compounds, ketal compounds, anthraquinone compounds, and thioxanthone compounds. Specific examples include benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, diethoxyacetophenone, benzyl dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzophenone, 2,4,6-trimethylbenzoin diphenylphosphine oxide, isoamyl N,N-dimethylaminobenzoate, 2-chlorothioxanthone, and 2,4-diethylthioxanthone. Furthermore, a known organic amine can also be added as a sensitizer.

[0038] The content of the photopolymerization initiator (D) is preferably 0.1 to 20 parts by mass, more preferably 1 to 15 parts by mass, per 100 parts by mass of the total of the compound (A) and the compound (B). Within this range, a sufficient polymerization initiation effect can be obtained, and this is effective in improving adhesion and scratch resistance.

[0039] The hard coat layer-forming composition of the present disclosure may further contain a sensitizer. The combined use of a photopolymerization initiator and a sensitizer can enhance photoreactivity. Examples of sensitizers include amine-based sensitizers, anthracene-based sensitizers, and thioxanthone-based sensitizers. Examples of amine-based sensitizers include trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, N,N-dimethylbenzylamine, and 4'-bis(diethylamino)benzophenone. Examples of anthracene-based sensitizers include 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, and 9,10-bis(2-ethylhexyloxy)anthracene. Examples of thioxanthone sensitizers include 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. Representative examples of commercially available sensitizers include EPA (manufactured by Nippon Kayaku Co., Ltd.) as an amine sensitizer, DBA and DEA (manufactured by Kawasaki Kasei Chemicals Co., Ltd.) as an anthracene sensitizer, and DETX and ITX (manufactured by Lambson) as thioxanthone sensitizers. Thioxanthone sensitizers have a sensitizing effect that is higher in reactivity and lower in discoloration after reaction than other amine sensitizers, and therefore thioxanthone sensitizers are preferred. When a sensitizer is used, its content is preferably 0.1 to 10 parts by mass relative to 100 parts by mass of the total of compound (A) and compound (B).

[0040] The composition for forming a hard coat layer of the present disclosure may contain other additives as needed, such as a plasticizer, a surface conditioner, a light stabilizer, an antioxidant, and a polymerization inhibitor.

[0041] The composition for forming a hard coat layer of the present disclosure preferably contains substantially no solvent, and the solvent content is 1.0% by mass or less. However, a small amount of solvent may be contained in order to increase the solubility of the photopolymerization initiator, sensitizer, and other additives.

[0042] Examples of the solvent include, although consideration must be given to odor consideration, known solvents such as aromatic organic solvents such as toluene and xylene, ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester organic solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate, and isobutyl acetate, alcohol organic solvents such as methanol, ethanol, n-propanol, isopropanol, and n-butanol, and glycol ether organic solvents such as propylene glycol monomethyl ether.

[0043] The content of the solvent in the composition for forming a hard coat layer is preferably 1.0 parts by mass or less, more preferably 0.5 parts by mass or less, and may be 0 parts by mass. Within this range, a sufficient polymerization initiation effect can be obtained, and it is effective in improving adhesion and scratch resistance. Among solvents that do not have reactivity with other components, it is more preferable that the content of a component that is liquid at 25°C and volatilizes and is removed at 250°C in the composition for forming a hard coat layer is 1.0 parts by mass or less, 0.5 parts by mass or less, or 0 parts by mass.

[0044] <Method for producing a composition for forming a hard coat layer> The composition for forming a hard coat layer of the present disclosure contains a compound (A), a compound (B), inorganic fine particles (C), a photopolymerization initiator (D), and, if necessary, a sensitizer and other additives. The production method is not particularly limited, but in order to reduce the use of solvent, it is preferable to pre-disperse the inorganic fine particles (C) using a low-viscosity compound (A), add and dissolve the photopolymerization initiator (D) therein, and then add the compound (B), and disperse and stir, thereby producing a composition for forming a hard coat layer with good dispersibility. It should be noted that known dispersants and surface treatment agents may be used during dispersion without any problems, and commercially available dispersed silica sol products such as SIRTPGDA30WT%-P02, SIRTPGDA50WT%-P08, and SIRTPGDA60WT%-P05 (manufactured by CIK Nanotech), Nanocryl C150 (manufactured by ARKEMA), and Optisol ASAM2100 (manufactured by RANCO) can be used.

[0045] <Hard Coat Film> The hard coat film of the present disclosure has a light-transmitting substrate and a hard coat layer. The hard coat layer is a cured product of the composition for forming a hard coat layer of the present disclosure.

[0046] The light-transmitting substrate may be a plastic substrate, and although not particularly specified, for example, a general light-transmitting film substrate such as polyethylene terephthalate (PET), triacetyl cellulose (TAC), polycarbonate, cycloolefin polymer (COP), acrylic, etc. The substrate may be a rigid substrate with high rigidity or a flexible substrate with high flexibility, but it is preferable to use a flexible substrate because it is suitable for winding.

[0047] The thickness of the hard coat layer is generally not particularly limited as long as it can be cured by irradiating it with ultraviolet light after application, but from a practical standpoint, it is often in the range of 2 μm to 15 μm.

[0048] The method for producing the hard coat film is not particularly limited and can be a conventionally known method, such as coating a hard coat layer-forming composition on a light-transmitting substrate. For example, the hard coat layer-forming composition of the present disclosure is coated on a polyethylene terephthalate substrate, and then the solvent is dried as necessary. By irradiating the coated hard coat layer-forming composition with active energy rays, the coated hard coat layer-forming composition is crosslinked and cured, thereby obtaining a hard coat film having a polyethylene terephthalate substrate and a hard coat layer.

[0049] Examples of the coating method include bar coating, blade coating, spin coating, reverse coating, die coating, spray coating, roll coating, gravure coating, microgravure coating, lip coating, air knife coating, and dipping.

[0050] Examples of active energy rays that can be used include electron beams and ultraviolet rays emitted from light sources such as xenon lamps, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, carbon arc lamps, and tungsten lamps.

[0051] The present disclosure will be described in more detail below. The present disclosure is not limited to the examples. Note that "parts by mass" is expressed as "parts" and "% by mass" is expressed as "%".

[0052] The abbreviations for the materials used in the examples are explained below.

[0053] (a1-1): VEEA: 2-(2-vinyloxyethoxy)ethyl acrylate, boiling point: 246°C / 760mmHg, viscosity: 3.65mPa·s / 25°C, VEEA manufactured by Nippon Shokubai Co., Ltd. (a1-2): VEEM: 2-(2-vinyloxyethoxy)ethyl methacrylate, boiling point: 257°C / 760mmHg, viscosity: 3.19mPa·s / 25°C, VEEM manufactured by Nippon Shokubai Co., Ltd. (a1-3): 14BDDA: 1,4-butanediol diacrylate, boiling point: 284°C / 760mmHg, viscosity: 5mPa·s / 25°C, Viscoat #195 manufactured by Osaka Organic Chemical Industry Ltd. (a2-1): LMA: dodecyl methacrylate (lauryl methacrylate), boiling point: 309°C / 760mmHg, viscosity: 4mPa·s / 25°C, LMA manufactured by Mitsubishi Chemical Corporation. (a2-2): BZA: benzyl acrylate, boiling point: 249°C / 760mmHg, viscosity: 2.68mPa·s / 25°C, Viscoat #160 manufactured by Osaka Organic Chemical Industry, Ltd. (a3-1): EG-DMA: ethylene glycol dimethacrylate, boiling point: 235°C / 760mmHg, viscosity: 3mPa·s / 25°C, NK Ester 1G manufactured by Shin-Nakamura Chemical Co., Ltd. (a4-1): INAA: isononyl acrylate, boiling point: 227°C / 760mmHg, viscosity: 2mPa·s / 25°C, INAA manufactured by Osaka Organic Chemical Industry, Ltd. (a5-1): EG-DA: ethylene glycol diacrylate, boiling point: 231.8°C / 760mmHg, viscosity: 14mPa·s / 25°C, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (a6-1): EHDG-A: 2-ethylhexyl diglycol acrylate, boiling point: 214°C / 760mmHg, viscosity: 7mPa·s / 25°C, Light Acrylate EHDG-AT: manufactured by Kyoeisha Chemical Co., Ltd. (a7-1): TPG-DA: tripropylene glycol diacrylate, boiling point: 362°C / 760mmHg, viscosity: 14mPa·s / 25°C, Viscoat #310HP: manufactured by Osaka Organic Chemical Industry Ltd. (a8-1): IBXA: isobornyl acrylate, boiling point: 254°C / 760 mHg, viscosity: 7.7 mPa·s / 25°C, IBXA: manufactured by Osaka Organic Chemical Industry Ltd.

[0054] (f1): MMA: methyl methacrylate, boiling point 144°C / 760 mmHg, 0.72 mPa·s / 25°C, manufactured by Mitsubishi Gas Chemical Company, Inc. (f2): DCP-DA: dimethyloltricyclodecane diacrylate, boiling point: 342°C / 760 mmHg, viscosity: 150 mPa·s / 25°C, light acrylate DCP-A: manufactured by Kyoeisha Chemical Co., Ltd. The viscosities of compound (a) and compound (b) used in the examples are values ​​measured at 25°C using an E-type viscometer: VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.), a rotation speed of 20 rpm, rotor No. 1, and a 1-minute value at 25°C.

[0055] (B1): DPHA-2C: a mixture of dipentaerythritol hexaacrylate (b1) / pentaerythritol tetraacrylate (b2) = 60 / 40, KARAYAD DPHA-2C: manufactured by Nippon Kayaku Co., Ltd. (B2): DPHA: dipentaerythritol hexaacrylate (b1), MIRAMER M-600: manufactured by MIWON Co., Ltd. (B3): PE-4A: pentaerythritol tetraacrylate (b2), MIRAMER M420: manufactured by MIWON Co., Ltd. (B4): TMP-3A: trimethylolpropane triacrylate (b3), SARTOMER SR-351S: manufactured by ARKEMA Co., Ltd.

[0056] (c1): SIRTPGDA30WT%-P02, primary particle diameter 30 nm, silica dispersion (silica: 30% by mass, tripropylene glycol diacrylate (a2-1): 70% by mass, manufactured by CIK Nanotech Co., Ltd. (c2): SIRTPGDA50WT%-P08, primary particle diameter 100 nm, silica dispersion (silica: 50% by mass content, tripropylene glycol diacrylate (a2-1): 50% by mass), manufactured by CIK Nanotech Co., Ltd. (c3): SIRTPGDA60WT%-P05, primary particle diameter 300 nm, silica dispersion (silica: 60% by mass, tripropylene glycol diacrylate (a2-1): 40% by mass), manufactured by CIK Nanotech Co., Ltd. (c4): Optisol ASAM2100, primary particle diameter 12 nm, silica dispersion (silica: 50 mass% content, tripropylene glycol diacrylate (a2-1): 50 mass%), manufactured by RANCO Corporation. The primary particle diameter of the inorganic fine particles (c) used in the examples was determined using a transmission electron microscope. Specifically, in an image observed using a transmission electron microscope (H-7650, manufactured by Hitachi, Ltd.), the major axis of any 100 inorganic fine particles (c) was determined, and the arithmetic average value thereof was taken as the primary particle diameter of the inorganic fine particles (c).

[0057] (d1): OMNIRAD 1173, 2-hydroxy-2-methyl-1-phenylpropanone, manufactured by IGM RESINS. (d2): OMNIRAD 184, 1-hydroxycyclohexyl-phenyl ketone, manufactured by IGM RESINS. (d3): ESACURE ONE, 1-propanone, 2-hydroxy-2-methyl-1-[4-(1-methylethenyl)phenyl]-, homopolymer, manufactured by IGM RESINS. (d4): IRGACURE OEX01, 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(o-benzoyloxime), manufactured by BASF Japan.

[0058] (e1): PGM: propylene glycol monomethyl ether, boiling point: 120°C / 760mHg, viscosity: 1.9mPa·s / 20°C, manufactured by Sankyo Chemical Co., Ltd.

[0059] Example 1 26 parts of a1-1 (VEEA), 50 parts of DPHA-2C (30 parts of (b1), 20 parts of (b2)), 3.6 parts of c1 (SIRTPGDA30WT%-P02), 8 parts of d1 (OMNIRAD 1173), and 4 parts of OMNIRAD184 were placed in a light-shielding glass bottle and mixed with a mix rotor to obtain composition 1 for forming a hard coat layer.

[0060] Subsequently, the hard coat layer-forming composition 1 was applied onto a 50 μm-thick PET film (Lumirror U403 manufactured by Toray Industries, Inc.) so that the film thickness after curing would be 5 μm. After irradiating the applied layer with ultraviolet light from a high-pressure mercury lamp with an output of 80 W / cm, the applied layer was cured to obtain a hard coat film 1.

[0061] <Examples 2 to 42, Comparative Examples 1 to 8> As shown in Tables 1 to 4, except that the compositions were changed, hard coat layer-forming compositions of Examples 2 to 42 and Comparative Examples 1 to 8 were produced in the same manner as in Example 1, and hard coat films were obtained using each of them.

[0062] [Measurement] The dispersed particle size and viscosity of the hard coat layer-forming compositions obtained in each of the Examples and Comparative Examples were measured by the following methods. The results are shown in Tables 1 to 4.

[0063] [Measurement of Average Dispersed Particle Diameter (D50)] The average dispersed particle diameter (D50) in the composition for forming a hard coat layer was measured using a particle size distribution measuring device ("UPA150-EX" manufactured by Microtrac-Bell Corporation) using dynamic light scattering. In the present disclosure, methyl ethyl ketone was used as the solvent, and the average value of three 60-second measurements was used at a concentration such that the loading index was in the range of 1.0±0.2.

[0064] [Viscosity Measurement] The viscosity of the obtained composition for forming a hard coat layer was measured under the following conditions: E-type viscometer: VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) Rotation speed: 20 rpm, rotor No. 1, 1 minute value at 25°C The measurement results were classified according to the following criteria. The results are shown in Tables 1 to 4. A: 20 mPa·s or more and less than 60 mPa·s B: 60 mPa·s or more and 120 mPa·s or less C: Less than 20 mPa·s or more than 120 mPa·s

[0065]

[0066]

[0067]

[0068]

[0069] [Evaluation] The hard coat films prepared using the compositions for forming a hard coat layer obtained in each of the Examples and Comparative Examples were evaluated by the following methods. The results are shown in Tables 5 to 8.

[0070] [Coatability] The appearance of the obtained hard coat film was visually observed and evaluated under the following conditions: 3: No unevenness on the coated surface: Good 2: Partial unevenness on the coated surface: Usable for practical use 1: Unevenness on the entire coated surface: Unusable for practical use

[0071] [Transparency] The obtained hard-coated film was cut into a piece of 10 cm x 10 cm, and the haze value was measured using a spectroscopic haze meter (SH7000, manufactured by Nippon Denshoku Industries Co., Ltd.). The transparency was evaluated according to the following evaluation criteria. Evaluation criteria: 4: Haze value less than 0.3%: Excellent; 3: Haze value 0.3% or more and less than 0.5%: Good; 2: Haze value 0.5% or more and 1.0% or less: Acceptable for practical use; 1: Haze value 1.1% or more: Unsuitable for practical use

[0072] [Anti-blocking property] Two obtained hard-coated films were placed together with their coated surfaces facing each other, and the anti-blocking property was evaluated based on the presence or absence of sticking when slid horizontally. Evaluation criteria: 4: Coated surfaces do not stick to each other and slide smoothly: Excellent 3: Coated surfaces stick to each other only at the edges, but slide smoothly: Good 2: Coated surfaces stick to each other partially other than the edges, but slide smoothly: Acceptable for practical use 1: Coated surfaces stick to each other and do not slide: Not suitable for practical use

[0073] [Scratch Resistance] A 1 cm2 square pad fitted with #0000 steel wool was placed on the surface of the sample and reciprocated 10 times with a load of 200 g, after which the appearance was visually evaluated and the number of scratches was counted. Evaluation criteria: 5: 0 scratches: Excellent; 4: 1 to less than 3 scratches: Excellent; 3: 3 to less than 7 scratches: Good; 2: 7 to less than 10 scratches: Usable; 1: 10 or more scratches: Unusable.

[0074] [Adhesion] Cellophane tape (Nichiban's Cellotape (registered trademark)) was applied to the obtained hard-coated film, and then vigorously peeled off, and the degree of peeling was evaluated. Evaluation criteria: 3: No peeling: Good; 2: Peeling occurred in more than 0% and less than 10% of the area where the cellophane tape was applied: Usable; 1: Peeling occurred in 10% or more of the area where the cellophane tape was applied: Unusable.

[0075] [Curing property] The surface of the obtained hard-coated film was rubbed with cloth gauze and visually evaluated to see whether or not a mark was left. Evaluation criteria: 4: No mark: Excellent 3: Partial mark: Good 2: Light mark on the entire surface: Usable 1: Clear mark on the entire surface: Unusable

[0076]

[0077]

[0078]

[0079]

[0080] Although the present invention has been described with reference to the above-mentioned several embodiments, the present invention is not limited to these several embodiments. Various modifications can be made to the configuration and details of the present invention within the scope of the present invention.

[0081] The disclosure of this application is related to the subject matter described in Japanese Patent Application No. 2023-217525, filed December 25, 2023, the entire disclosure of which is incorporated herein by reference.

Claims

1. A composition for forming a hard coat layer, comprising a compound (A) having one or two ethylenically unsaturated groups, having a viscosity at 25°C of 1 to 30 mPa·s and a boiling point at 1 atm of 200°C or higher, a compound (B) having three or more ethylenically unsaturated groups, inorganic fine particles (C), and a photopolymerization initiator (D), wherein the mass ratio (A / B) of the compound (A) to the compound (B) is 30 / 70 to 80 / 20, and the content of the solvent in 100% by mass of the composition for forming a hard coat layer is 1% by mass or less.

2. The composition for forming a hard coat layer according to claim 1, wherein the content of a compound (a1) having two ethylenically unsaturated groups, having a viscosity at 25°C of 1 mPa·s or more and less than 6 mPa·s, and a boiling point at 1 atm of 240°C or higher, in 100% by mass of the compound (A) is 70% by mass or more.

3. The composition for forming a hard coat layer according to claim 1, containing 1.0 part by mass or more and less than 10 parts by mass of the inorganic fine particles (C) with respect to a total of 100 parts by mass of the compound (A) and the compound (B).

4. The composition for forming a hard coat layer according to claim 1, wherein the average dispersed particle diameter (D50) of the inorganic fine particles (C) in the composition for forming a hard coat layer is 20 to 400 nm.

5. The composition for forming a hard coat layer according to claim 1, wherein the inorganic fine particles (C) are silica fine particles.

6. The composition for forming a hard coat layer according to claim 1, having a viscosity at 25°C of 20 to 120 mPa·s.

7. A hard coat film having a light-transmissive substrate and a hard coat layer, wherein the hard coat layer is a cured product of the composition for forming a hard coat layer according to any one of claims 1 to 6.

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