JP2023084164A - Low refractive index layer formation coating liquid, low refractive index layer, and reflection prevention film - Google Patents

Abstract

To provide a low refractive index layer coating liquid for a reflection prevention film which is highly resistive to abrasion by various different types of polishing materials and is also highly anti-fouling.SOLUTION: A low refractive index layer formation coating liquid includes: hollow particles (A) with particle diameters (D50) of 150 nm or less; inorganic oxide fine particles (B) with particle diameters (D50) of 10-90 nm and particle diameters (D99) of 150-300 nm [excluding the hollow particles (A)]; and polyfunctional (meta) acrylate (C), the liquid containing 0.5-15 pts.mass of the inorganic oxide fine particles (B) with respect to 100 pts.mass of the hollow particles (A).SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a coating liquid for forming a low refractive index layer, a low refractive index layer, and an antireflection film.

An image display surface of an image display device such as a liquid crystal display, an organic EL display, or a touch panel is provided with an antireflection film or an antiglare film having a low refractive index layer in order to suppress reflection of external light.

The antireflection film consists of light reflected on the surface of the low refractive index layer and light reflected on the interface between the low refractive index layer and a layer adjacent to the low refractive index layer (for example, a hard coat layer or a high refractive index layer). , the reflectance is reduced by the interference effect of light.

An antireflection film is often laminated on the outermost layer of a display, and is required to have scratch resistance and abrasion resistance.

In Patent Document 1, convex portions are formed on the surface of the low refractive index layer by adding inorganic oxide particles having an average particle size larger than the average thickness of the low refractive index layer. The raised portions on the surface improve the scratch resistance against steel wool. Since solid inorganic particles are more resistant to scratches than soft organic polymer resins, forming protrusions with inorganic particles on the surface makes it difficult for abrasives to contact the surface layer of the polymer resin, resulting in scratch resistance for the entire layer. improve sexuality.

WO2021/020504

In addition, since the antireflection film is used in image display devices such as various displays, antifouling properties on the surface and wiping-off properties are required. When wiping off dirt, it is often wiped off with gauze or cloth impregnated with alcohol such as ethanol, and abrasion resistance to gauze is required.

However, when irregularities are formed on the surface of the low refractive index layer described in Patent Document 1, rigid fiber abrasives such as steel wool are grounded to the convex portions of the surface layer when a load is applied, and the polymer While it is difficult to make contact with the resin surface layer, highly flexible fibers such as gauze and cotton cloth such as gold cloth are relatively easy to contact not only the convex portions of the surface layer but also the concave portions. Therefore, even if the scratch resistance against steel wool can be improved, the surface smoothness is lowered, and the slipperiness against abrasives is lowered, so the scratch resistance against gauze and the like is inferior.

Therefore, in the present invention, surface smoothness is used to form a low refractive index layer that has high scratch resistance to both rigid fibers such as steel wool and flexible fibers such as gauze. The purpose is to achieve both the robustness due to inorganic fine particles and the inorganic fine particles. Another object of the present invention is to achieve the transparency, low reflectance, and antifouling properties required for antireflection films.

That is, the problem to be solved by the present invention is to provide a coating liquid for forming a low refractive index layer for an antireflection film which is excellent in scratch resistance against various abrasives and also excellent in antifouling properties.

The present inventors have made intensive studies to solve the above problems, and as a result, have arrived at the following invention. That is, the first invention is hollow particles (A) having a particle diameter (D ₅₀ ) of 150 nm or less and inorganic oxide fine particles having a particle diameter (D ₅₀ ) of 10 to 90 nm and a particle diameter (D ₉₉ ) of 150 to 300 nm. (B) (excluding hollow particles (A)) and polyfunctional (meth)acrylate (C),
The coating liquid for forming a low refractive index layer contains 0.5 to 15 parts by mass of the inorganic oxide fine particles (B) based on 100 parts by mass of the hollow particles (A).

A second invention relates to the coating liquid for forming a low refractive index layer, which further contains a fluorine-containing (meth)acrylate (D).

In addition, the third invention is the low The present invention relates to a coating liquid for forming a refractive index layer.

A fourth invention relates to the low refractive index layer-forming coating liquid, wherein the polyfunctional (meth)acrylate (C) contains a polyfunctional (meth)acrylate having a silicone chain.

A fifth invention relates to a low refractive index layer formed from the low refractive index layer-forming coating liquid.

In a sixth aspect of the present invention, the low refractive index layer has a surface water contact angle of 90° or more, and a haze change of 0.1 or less when 10 reciprocations are performed with a load of 200 g/cm2 according to a steel wool test. Regarding.

A seventh invention relates to an antireflection film comprising the low refractive index layer on a transparent substrate.

An eighth invention relates to the antireflection film having a luminous reflectance of 1.5% or less.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a coating liquid for forming a low refractive index layer for an antireflection film which is excellent in scratch resistance against various abrasives and also excellent in antifouling properties.

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below, but first, terms used in this specification will be described. In the present specification, when expressed as "(meth)acryl", "(meth)acrylo", "(meth)acrylic acid", "(meth)acrylate", and "(meth)acryloyloxy" , unless otherwise indicated, shall denote "acrylic or methacrylic", "acrylo or methacrylo", "acrylic acid or methacrylic acid", "acrylate or methacrylate" and "acryloyloxy or methacryloyloxy" respectively. In addition, "hollow particles (A) having a particle diameter (D ₅₀ ) of 150 nm or less" are referred to as "hollow particles (A)", and "particle diameter (D ₅₀ ) is 10 to 90 nm and particle diameter (D ₉₉ ) is 150 to 300 nm inorganic oxide fine particles (B)" are sometimes referred to as "inorganic oxide fine particles (B)".
Moreover, the low refractive index in the present invention means that the refractive index is 1.45 or less.
In addition, the particle size ( _D50 ) and particle size ( _D99 ) represent the particle size at which the cumulative value is 50% and 99%, respectively, in the volume-based particle size distribution obtained from the particle size distribution measurement value. It can be determined by a Nanotrac particle size distribution measuring device using a selective light scattering method.
Also, the luminous reflectance is determined according to JIS Z8722.
Unless otherwise noted, the various components appearing in this specification may be used singly or in admixture of two or more.

<<Coating liquid for forming low refractive index layer>>
The coating liquid for forming _{a low refractive index layer contains hollow particles (A) having a particle diameter (D 50 )} of 150 _nm or less, and including inorganic oxide fine particles (B) and a polyfunctional (meth)acrylate (C),
The inorganic oxide fine particles (B) are contained in an amount of 0.5 to 15% by mass based on 100% by mass of the hollow particles (A).

<Hollow particles (A)>
The hollow particles (A) are hollow particles having a particle diameter (D ₅₀ ) of 150 nm or less, and the hollow particles include hollow silica particles, hollow polymer particles and the like having voids inside.
Polymers constituting the hollow polymer particles include crosslinked acrylic polymers, crosslinked styrene polymers, vinyl polymers and the like. A crosslinked acrylic polymer is preferable from the viewpoint of achieving a low refractive index.
Commercially available products include Sururia 4320 (particle diameter (D ₅₀ ) 60 nm, JGC Shokubai Kasei) as hollow silica particles, and Techpolymer XX5964Z (particle diameter (D ₅₀ ) 80 nm, Sekisui Plastics Co., Ltd.) as hollow polymer particles. .

The particle diameter (D ₅₀ ) is 150 nm or less, preferably 80 nm or less from the viewpoint of haze and gauze resistance. Although the lower limit is not particularly limited, it is preferably 40 nm or more in order to improve the refractive index.
The particle diameter (D ₅₀ ) of the hollow particles can be obtained with a Nanotrack particle size distribution measuring device using a dynamic light scattering method.
Examples of the Nanotrac particle size distribution analyzer include "Nanotrac UPA" manufactured by Nikkiso Co., Ltd., and the like.
Specifically, it can be measured by adding it to a diluted solution so that the loading index value in the analysis software "Microtrac" becomes 1.0.
As the diluent, it is preferable to use the same dispersion solvent as the main component of the dispersion solvent for the hollow particles, such as methyl isobutyl ketone, methyl ethyl ketone, and propylene glycol monomethyl ether.

In order to reduce the refractive index, the content of the hollow particles is preferably 10 to 80% by mass based on 100% by mass of the non-volatile content of the coating liquid for forming the low refractive index layer. More preferably 15 to 70% by mass.

<Inorganic oxide fine particles (B)>
The inorganic oxide fine particles (B) are inorganic oxide fine particles having a particle diameter (D ₅₀ ) of 10 to 90 nm and a particle diameter (D ₉₉ ) of 150 to 300 nm. However, hollow particles (A) are excluded.
As a result, haze and coloring can be reduced, so that a low refractive index layer with excellent transparency can be obtained. In order to achieve both transparency and scratch resistance, the particle diameter (D ₉₉ ) is preferably 180-280 nm, more preferably 200-250 nm.
In order to improve the scratch resistance of the low refractive index layer, the particle diameter (D ₅₀ ) of the inorganic oxide fine particles (B) is preferably 50-90 nm, more preferably 65-90 nm.
Incidentally, the dispersed particle size of the inorganic oxide fine particles can be determined by a Microtrac particle size distribution analyzer using a dynamic light scattering method or the like.
Examples of the Microtrac particle size distribution analyzer include "Nanotrac UPA" manufactured by Nikkiso Co., Ltd., and the like.
Specifically, an inorganic oxide fine particle dispersion obtained by dispersing inorganic oxide fine particles in a solvent can be added to a diluted solution so that the loading index value becomes 1.0, and the measurement can be performed.
As the diluent, it is preferable to use the same dispersing solvent as the main component of the dispersing solvent for the inorganic oxide fine particles, and examples thereof include methyl isobutyl ketone, methyl ethyl ketone, and propylene glycol monomethyl ether.

Although the inorganic oxide fine particles to be used are not particularly limited, aluminum oxide (Al ₂ O ₃ ) or silica (SiO ₂ ) fine particles are exemplified from the viewpoint of transparency and scratch resistance.
From the viewpoint of transparency and scratch resistance, aluminum oxide fine particles are preferred, and furthermore, in order to improve scratch resistance, the crystal structure of the aluminum oxide fine particles is preferably θ-type and/or α-type.

The content of the inorganic oxide fine particles (B) is from 0.3 to 0.3 in the non-volatile content of 100% by mass of the coating liquid for forming the low refractive index layer, from the viewpoint of achieving both scratch resistance, low refractive index, and transparency. It is preferably 5% by mass, more preferably 0.4 to 3% by mass.

The content of the inorganic oxide fine particles (B) is 0.5 to 15 parts by mass, preferably 1 to 10 parts by mass, and 1 to 5 parts by mass with respect to 100 parts by mass of the hollow particles (A). is more preferable. Within this range, both scratch resistance and transparency can be achieved.

<Polyfunctional (meth)acrylate (C)>
Polyfunctional (meth)acrylate (C) is not limited as long as it is a compound having two or more (meth)acrylate groups.
As the polyfunctional (meth)acrylate (C),
Trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate , polyol poly (meth) acrylate compounds such as;
Tris(2-acryloxyethyl) isocyanurate, EO-modified tris(2-acryloxyethyl) isocyanurate, PO-modified tris(2-acryloxyethyl) isocyanurate, and ε-caprolactone-modified tris(2-acryloxyethyl) trimers (isocyanurates) of (meth)acrylates having isocyanate groups such as isocyanurates;
In addition, polyacrylates of polymer polyols such as polyacrylic poly(meth)acrylates, polyurethane poly(meth)acrylates, and polyester (meth)acrylates having three or more (meth)acryloyl groups;
polyepoxy (meth)acrylate;
etc., but not limited to these.

Moreover, from the viewpoint of scratch resistance and antifouling properties, the polyfunctional (meth)acrylate (C) is preferably a polyfunctional (meth)acrylate having a silicone chain.
A silicone chain in the present invention is a skeleton having a siloxane bond.

Commercially available polyfunctional (meth)acrylates (C) include tris(2-acryloxyethyl) isocyanurate (FANCRYL FA-731A manufactured by Hitachi Chemical Co., Ltd., NEW FRONTIER TEICA (GX-8430) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., etc. ), EO-modified tris (2-acryloxyethyl) isocyanurate (Toagosei Co., Ltd. Aronix M-313, M-315, Shin-Nakamura Chemical Co., Ltd. NK Ester A-9300, ARKEMA Co., Ltd. SARTOMER SR-368, etc.), Commercially available products such as PO-modified tris(2-acryloxyethyl) isocyanurate and ε-caprolactone-modified tris(2-acryloxyethyl) isocyanurate (NK Ester A-9300-1CL manufactured by Shin-Nakamura Chemical Co., Ltd.) can be mentioned. but not limited to these.

The content of the polyfunctional (meth)acrylate (C) is 10 to 90% by mass in 100% by mass of the non-volatile content of the low refractive index layer-forming coating liquid, from the viewpoint of achieving both scratch resistance and a low refractive index. is preferred, and 20 to 80% by mass is more preferred.

<Fluorine-containing (meth)acrylate (D)>
The fluorine-containing (meth)acrylate (D) is not limited as long as it is a (meth)acrylate having a fluorine atom, and examples thereof include (meth)acrylates having a perfluoropolyether skeleton.
Commercially available products include FLUOROLINK AD1700 (manufactured by Solvay) and Megafac RS-90 (manufactured by DIC).

By containing the fluorine-containing (meth)acrylate (D), the water contact angle of the surface can be improved, and the antifouling property can be improved. The content of the fluorine-containing (meth)acrylate is preferably 1 to 11% by mass, more preferably 1.4 to 8% by mass, based on 100% by mass of the non-volatile content of the coating liquid for forming the low refractive index layer.

<Optional component>
The coating liquid for forming a low refractive index of the present invention may further contain various additives. Additives include photopolymerization initiators, thermosetting resins, polymerization inhibitors, leveling agents, slip agents, antifoaming agents, surfactants, antibacterial agents, antiblocking agents, plasticizers, ultraviolet absorbers, and infrared absorbers. , antioxidants, silane coupling agents, conductive agents, inorganic fillers, and the like.

《Anti-reflection film》
The antireflection film of the present invention has a low refractive index layer formed from the low refractive index forming coating liquid of the present invention on a transparent substrate.
As a result, an antireflection film having excellent scratch resistance against various abrasives and excellent antifouling properties can be obtained.
The antireflection film may further have a hard coat layer or other cured film layer such as an optical adjustment layer, and preferably comprises a hard coat layer and a low refractive index layer on the transparent substrate in this order. . Another cured film layer or the like may be provided between the transparent substrate layer and the hard coat layer or between the hard coat layer and the low refractive index layer. It is also preferable to provide a hard coat layer, an optical adjustment layer and a low refractive index layer in this order on a transparent substrate.
The antireflection film of the present invention has a luminous reflectance of 1.5% or less, preferably 1.2% or less, more preferably 1% or less from the viewpoint of antireflection properties.

[Low refractive index layer]
The low refractive index layer is formed from the coating solution for forming a low refractive index layer of the present invention. be done.

The low refractive index layer has a refractive index of 1.45 or less, preferably 1.41 or less in order to reduce the reflectance.
The thickness of the low refractive index layer is preferably 80 to 150 nm, more preferably 100 to 140 nm, in order to reduce the reflectance.

The contact angle with water is preferably 90° or more, whereby an antireflection film having excellent antifouling properties can be obtained. Further, the higher the water contact angle, the higher the antifouling property. Therefore, it is preferably 100° or more, more preferably 110° or more.

[Transparent substrate]
The transparent substrate is not particularly limited as long as it is a substrate having optical transparency, and examples thereof include glass, synthetic resin moldings, and films.
Although the thickness of the base material is not particularly limited, it is usually about 50 to 200 μm.

Synthetic resin moldings include polymethyl methacrylate resin, copolymer resin mainly composed of methyl methacrylate, polystyrene resin, styrene-methyl methacrylate copolymer resin, styrene-acrylonitrile copolymer resin, polycarbonate resin, cellulose acetate butyrate. Molded articles of synthetic resins such as rate resins, polyallyl diglycol carbonate resins, polyvinyl chloride resins, and polyester resins can be mentioned.

Examples of films include polyester film, polyethylene film, polypropylene film, cellophane film, diacetylcellulose film, triacetylcellulose (TAC) film, acetylcellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, and polyvinyl alcohol. Film, ethylene vinyl alcohol film, polyolefin film, polystyrene film, polycarbonate film, polymethylpentel film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, polyimide film, fluororesin film, nylon film , acrylic film, and the like.

[Hard coat layer]
The hard coat layer can be formed using a conventionally known coating liquid for forming a hard coat layer, and is not particularly limited. It is obtained by laminating a coating liquid for forming a coat layer on a substrate.
The thickness of the hard coat layer is usually about 0.5 μm to 5 μm, preferably about 3 to 5 μm for scratch resistance. The refractive index is about 1.5-1.8.
From the viewpoint of antireflection, the refractive index is preferably 1.50 or more, more preferably 1.60 or more.

[Optical adjustment layer]
The optical adjustment layer can be formed using a conventionally known coating liquid for forming an optical adjustment layer, and is not particularly limited. is obtained by laminating a known coating liquid for forming an optical adjustment layer containing the above on the substrate or the hard coat layer.
The thickness of the optical adjustment layer is usually about 30 to 500 nm, preferably about 50 to 300 nm from the viewpoint of antireflection. The refractive index is about 1.60 to 1.9, preferably 1.65 or more from the viewpoint of antireflection.

[Manufacturing method of antireflection film]
The method for producing the antireflection film is not particularly limited. For example, the antireflection film can be obtained by forming a low refractive index layer on a base material using a low refractive index layer-forming coating liquid. Further, when a hard coat layer is provided, for example, an antireflection film can be obtained by forming a hard coat layer on a base material and further laminating a low refractive index layer on the hard coat layer. In addition, another cured film layer such as an optical adjustment layer may be provided between the base material layer and the hard coat layer or between the hard coat layer and the low refractive index layer.
The film thickness of the antireflection film is usually about 50 to 200 μm.

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples below, but the following examples do not limit the technical scope of the present invention.
The compounding amounts in the table are expressed in % by mass, and values other than the solvent are converted to non-volatile matter. A blank column in the table indicates that it was not blended.
The average particle size of the hollow particles and the inorganic oxide fine particles and the film thickness of the low refractive index layer were measured by the following methods.

<Average particle size of hollow particles and inorganic oxide fine particles>
"Nanotrack UPA" manufactured by Nikkiso Co., Ltd. was used as a nanotrack particle size distribution analyzer using a dynamic light scattering method.
The hollow particles and the inorganic oxide fine particles were added to the diluted solution so that the loading index value was 1.0, and the measurement was performed. Depending on the dispersion solvent for the hollow particles and the inorganic oxide fine particles, the diluent used was the same as the dispersion solvent for the main component.

<Film thickness of low refractive index layer>
The film thickness of the low refractive index layer was measured using an optical non-contact film thickness meter (FILMETRICS, Inc, F20 film thickness measurement device).

<Production of polyfunctional polyester acrylate>
(Production of polyfunctional polyester acrylate PE1)
80.0 parts of 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride and a pentavalent hydroxyl value of 122 mgKOH/g were placed in a four-necked flask equipped with a stirrer, a reflux condenser, a dry air inlet tube, and a thermometer. Erythritol triacrylate (Nippon Kayaku pentaerythritol triacrylate trade name: KAYARAD PET-30, containing pentaerythritol tetraacrylate as a by-product) 250.0 parts, methylhydroquinone 0.24 parts, cyclohexanone 217.8 parts After charging, the temperature was raised to 60°C. Then, 1.65 parts of 1,8-diazabicyclo[5.4.0]-7-undecene was added as a catalyst and stirred at 90° C. for 8 hours. After that, 78.3 parts of methacryl glycidyl ether, 54.0 parts of cyclohexanone are added, and then 2.65 parts of dimethylbenzylamine as a catalyst are added, and the mixture is stirred at 100° C. for 6 hours, and the reactants are periodically added while continuing the reaction. was measured, and when the acid value became 5.0 mgKOH/g or less, the reaction was terminated by cooling to room temperature. The obtained resin varnish was light yellow and transparent, and was a mixture of polyester acrylate and pentaerythritol tetraacrylate having a solid content of 60% (solid content mass ratio: polyester acrylate: pentaerythritol tetraacrylate = 76: 24). An acrylate PE1 solution was obtained. Polyfunctional polyester acrylate PE1 had 8 functional groups and a weight average molecular weight of 3,500.

<<Inorganic oxide fine particles (B)>>
<Production of Aluminum Oxide Fine Particle Dispersion>
[Aluminum oxide fine particle dispersion (1)]
35 parts of aluminum oxide (1) (θ-type crystal, primary particle size: 10 nm), 14 parts of polyfunctional polyester acrylate PE1 in terms of solid content, 25.5 parts of methyl ethyl ketone as an organic solvent, and 25.5 parts of methoxybutanol were mixed. After stirring with a disper, dispersion treatment was performed in a sand mill to obtain a uniform aluminum oxide fine particle dispersion (1) containing θ-type crystal aluminum oxide fine particles (B-1). The aluminum oxide fine particles (B-1) had a particle size (D ₅₀ ) of 80 nm and a particle size (D ₉₉ ) of 200 nm.

[Aluminum oxide fine particle dispersion (2)]
The same procedure as in Production Example 1 except that 14.3 parts of aluminum oxide (1), 5.7 parts of polyfunctional polyester acrylate PE1 in solid content, 40 parts of methyl ethyl ketone as an organic solvent, and 40 parts of methoxybutanol were mixed. to obtain a uniform aluminum oxide fine particle dispersion (2) containing θ-type crystal aluminum oxide fine particles (B-2). The aluminum oxide fine particles (B-2) had a particle size (D ₅₀ ) of 60 nm and a particle size (D ₉₉ ) of 160 nm.

[Aluminum oxide fine particle dispersion (3)]
Dispersion treatment was carried out in the same manner as in Production Example 1, except that aluminum oxide (2) (θ-type crystal, primary particle size: 30 nm) was used, resulting in uniform aluminum oxide containing θ-type crystal aluminum oxide fine particles (B-3). A fine particle dispersion (3) was obtained. The aluminum oxide fine particles (B-3) had a particle size (D ₅₀ ) of 90 nm and a particle size (D ₉₉ ) of 280 nm.

[Aluminum oxide fine particle dispersion (4)]
Dispersion treatment was carried out in the same manner as in Production Example 2 except that aluminum oxide (3) (α-type crystal primary particle size: 30 nm) was used, resulting in uniform aluminum oxide containing α-type crystal aluminum oxide fine particles (B-4). A fine particle dispersion (4) was obtained. The aluminum oxide fine particles (B-4) had a particle diameter (D ₅₀ ) of 80 nm and a particle diameter (D ₉₉ ) of 200 nm.

[Aluminum oxide fine particle dispersion (5)]
Dispersion treatment was performed in the same manner as in Production Example 1 except that aluminum oxide (4) (γ-type crystal, primary particle size: 10 nm) was used, and uniform dispersion of alumina containing γ-type crystal aluminum oxide fine particles (B-5) was performed. Body (5) was obtained. The aluminum oxide fine particles (B-5) had a particle diameter (D ₅₀ ) of 80 nm and a particle diameter (D ₉₉ ) of 200 nm.

[Aluminum oxide fine particle dispersion (6)]
Dispersion treatment was carried out in the same manner as in Production Example 2 except that aluminum oxide (5) (α-type crystal, primary particle size: 50 nm) was used, and uniform oxidation containing α-type crystal aluminum oxide fine particles (B'-1) was performed. An aluminum fine particle dispersion (6) was obtained. The aluminum oxide fine particles (B'-1) had a particle diameter (D ₅₀ ) of 110 nm and a particle diameter (D ₉₉ ) of 280 nm.

[Aluminum oxide fine particle dispersion (7)]
Dispersion treatment was carried out in the same manner as in Production Example 1 except that aluminum oxide (3) (α-type crystal, primary particle size: 30 nm) was used, and uniform oxidation containing α-type crystal aluminum oxide fine particles (B′-2) was performed. An aluminum fine particle dispersion (5) was obtained. The aluminum oxide fine particles (B'-2) had a particle diameter (D ₅₀ ) of 90 nm and a particle diameter (D ₉₉ ) of 320 nm.

[Aluminum oxide fine particle dispersion (8)]
Dispersion treatment was carried out in the same manner as in Production Example 2 except that aluminum oxide (4) (γ-type crystal, primary particle size: 10 nm) was used, and uniform alumina containing γ-type crystal aluminum oxide fine particles (B'-3) was obtained. Dispersion (8) was obtained. The aluminum oxide fine particles (B'-3) had a particle diameter (D ₅₀ ) of 60 nm and a particle diameter (D ₉₉ ) of 140 nm.

<Silica fine particles>
Inorganic oxide fine particles (B-6): MEK-AC-2140Y (manufactured by Nissan Chemical Industries, Ltd., silica fine particles, particle diameter (D ₅₀ ) of 20 nm, particle diameter (D ₉₉ ) of 150 nm)

The types, crystal systems, and average particle sizes of the inorganic oxide fine particles are summarized below.

<Preparation of Coating Liquid for Forming Hard Coat Layer or Optical Adjustment Layer>
[Coating solution 1 for forming hard coat layer or optical adjustment layer (coating solution 1)]
100 parts of zirconium oxide particles, 155.4 parts of polyfunctional polyester acrylate PE1, 4.6 parts of ESACURE ONE (manufactured by IGM RESINS Co., Ltd.) as a photopolymerization initiator, and propylene glycol monomethyl ether as an organic solvent. The concentration was adjusted to 40% to obtain a coating liquid 1 for forming a hard coat layer or an optical adjustment layer (coating liquid 1).

[Coating solution 2 for forming hard coat layer or optical adjustment layer (coating solution 2)]
155.4 parts of polyfunctional polyester acrylate PE1, 4.6 parts of ESACURE ONE (manufactured by IGM RESINS Co., Ltd.) as a photopolymerization initiator, and propylene glycol monomethyl ether as an organic solvent so that the concentration of nonvolatile matter is 40%. to obtain a coating liquid 2 for forming a hard coat layer or an optical adjustment layer (coating liquid 2).

[Coating solution 3 for forming hard coat layer or optical adjustment layer (coating solution 3)]
100 parts of titanium oxide particles, 60 parts of polyfunctional polyester acrylate PE1, 3 parts of ESACURE ONE (manufactured by IGM RESINS Co., Ltd.) as a photopolymerization initiator, and propylene glycol monomethyl ether as an organic solvent at a nonvolatile concentration of 40%. A coating solution 3 for forming a hard coat layer or an optical adjustment layer (coating solution 3) was obtained.

The materials used in the production of Examples and Comparative Examples are as follows.
<Hollow particles>
Hollow particles (A-1); Techpolymer XX-5964Z (hollow polymer particles, crosslinked acrylic resin, particle diameter (D ₅₀ ) 80 nm, hollowness 43%, solid content 10%, Sekisui Plastics Co., Ltd. made)
Hollow particles (A-2); hollow polymer particles, vinyl resin, particle diameter (D ₅₀ ) 150 nm, solid content 10%
Hollow particles (A-3): Sururia 4320 (hollow silica particles, particle diameter (D ₅₀ ) 60 nm, particle refractive index 1.30, solid content 20.5%, manufactured by Nikki Shokubai Kasei Co., Ltd.)
· Hollow particles (A'-1); hollow silica particles, particle diameter (D ₅₀ ) 200 nm, solid content 20.5%

<Polyfunctional (meth)acrylate (C)>
・ SIU2400; Miramer SIU2400 (10-functional urethane acrylate containing silicone chain, molecular weight 8000, manufactured by Miwon)
DPHA-2C; KAYARAD DPHA-2C (a mixture of dipentaerythritol hexaacrylate and pentaerythritol tetraacrylate, manufactured by Nippon Kayaku Co., Ltd.)
・Polyfunctional polyester acrylate PE1

<Fluorine-containing (meth)acrylate (D)>
Fluorine-containing (meth)acrylate (D-1); FLUOROLINK AD1700 (perfluoropolyether urethane acrylate, solid content 65%, manufactured by Solvay)
Fluorine-containing (meth)acrylate (D-2); Megafac RS-90 (fluorine-containing UV reactive oligomer, solid content 10%, manufactured by DIC)

<Photoinitiator>
・ OMNIRAD907 (manufactured by IGM RESINS Co., Ltd.)

[Example 1]
<Preparation of coating solution for forming low refractive index layer>
Hollow particles (A-1) as hollow particles (A) (Techpolymer XX-5964Z, hollow polymer particles, crosslinked acrylic resin, average particle size 80 nm, manufactured by Sekisui Plastics Co., Ltd.) 100 parts (solid content 100 % conversion value), 100 parts of Miramer SIU2400 (manufactured by Miwon) as the polyfunctional (meth)acrylate (C), fluorine-containing (meth)acrylate (D-1) as the fluorine-containing (meth)acrylate (D) (FLUOROLINK AD1700 (Solvay Co., Ltd.)) 15 parts (converted to 100% solid content), 4 parts of alumina dispersion (1) and 5 parts of OMNIRAD 907 (manufactured by IGM RESINS Co., Ltd.) as a photopolymerization initiator are mixed well, and propylene as an organic solvent Glycol monomethyl ether was adjusted to have a non-volatile content of 4% to obtain a coating liquid X1 for forming a low refractive index layer.
Since the aluminum fine particles (B-1) are contained in the alumina dispersion (1) in an amount of 25% by mass, the ratio of the hollow particles (A-1) to the alumina fine particles (B-1) is 100:1.
In addition, the fluorine-containing (meth)acrylate (D) is contained in the non-volatile matter in an amount of 6.78% by mass.
Polyfunctional polyester acrylate PE1 is contained in alumina dispersion (1) in an amount of 10% by mass.

<Production of antireflection film>
On a polyethylene terephthalate (PET) film with a thickness of 50 μm (“Lumirror UH-13” manufactured by Toray Industries, Inc.), a hard coat layer forming coating liquid 1 (coating liquid 1) is applied using a bar coater. After coating so as to have a film thickness of 3.0 μm, a hard coat layer was formed by irradiating ultraviolet rays of 400 mJ/cm ² with a high-pressure mercury lamp. On the hard coat layer, the obtained coating liquid X1 for forming a low refractive index layer was coated using a bar coater so that the film thickness after drying was 100 nm, and then the oxygen concentration was 500 ppm or less. A low refractive index layer was formed by irradiating ultraviolet rays of 400 mJ/cm ² with a high-pressure mercury lamp in a nitrogen atmosphere to obtain an antireflection film.

[Examples 2 to 19, Comparative Examples 1 to 7]
Low refractive index layer-forming coating solutions X2 to X26 having a nonvolatile content concentration of 4% were obtained in the same manner as in Example 1, except that the compositions and blending amounts (in terms of nonvolatile content) shown in Tables 1 to 3 were used.
Subsequently, antireflection films were obtained in the same manner as in Example 1, except that the low refractive index layer-forming coating liquids X2 to X26 were used.

[Examples 20, 21, 28]
In the same manner as in Example 1, a coating liquid X1 for forming a low refractive index layer was obtained.
As shown in Table 5, a 50 μm thick polyethylene terephthalate (PET) film (“Lumirror UH-13” manufactured by Toray Industries, Inc.) or an 80 μm thick triacetyl cellulose (TAC) film (manufactured by Fuji Film Co., Ltd. “ FUJITAC"), hard coat layer forming coating liquids 1 to 3 (coating liquids 1 to 3) were applied using a bar coater so that the film thickness after drying was 3.0 μm, and then high pressure A hard coat layer was formed by irradiating ultraviolet rays of 400 mJ/cm ² with a mercury lamp. On the hard coat layer, the obtained coating liquid X1 for forming a low refractive index layer was coated using a bar coater so that the film thickness after drying was 100 nm, and then the oxygen concentration was 500 ppm or less. A low refractive index layer was formed by irradiating ultraviolet rays of 400 mJ/cm ² with a high-pressure mercury lamp in a nitrogen atmosphere to obtain an antireflection film.

[Example 22]
In the same manner as in Example 1, a coating liquid X1 for forming a low refractive index layer was obtained.
The resulting coating liquid X1 for forming a low refractive index layer was dried on a 50 μm thick polyethylene terephthalate (PET) film (“Lumirror UH-13” manufactured by Toray Industries, Inc.) using a bar coater. After coating so that the thickness is 100 nm, a low refractive index layer is formed by irradiating 400 mJ / cm ² ultraviolet rays with a high pressure mercury lamp in a nitrogen atmosphere with an oxygen concentration of 500 ppm or less to form an antireflection film. got

[Examples 23 and 24]
In the same manner as in Example 1, a coating liquid X1 for forming a low refractive index layer was obtained.
As shown in Table 5, coating solution 1 or 3 was applied onto a 50 μm thick polyethylene terephthalate (PET) film (“Lumirror UH-13” manufactured by Toray Industries, Inc.) using a bar coater. After coating so as to have a thickness of 100 nm, an optical adjustment layer was formed by irradiating ultraviolet rays of 400 mJ/cm ² with a high-pressure mercury lamp. After coating the obtained coating liquid X1 for forming a low refractive index layer on the optical adjustment layer using a bar coater so that the film thickness after drying becomes 100 nm, the oxygen concentration becomes 500 ppm or less. A low refractive index layer was formed by irradiating ultraviolet rays of 400 mJ/cm ² with a high-pressure mercury lamp in a nitrogen atmosphere to obtain an antireflection film.

[Examples 25-27]
In the same manner as in Example 1, a coating liquid X1 for forming a low refractive index layer was obtained.
As shown in Table 5, coating solution 1 or 2 was applied to a 50 μm thick polyethylene terephthalate (PET) film (“Lumirror UH-13” manufactured by Toray Industries, Inc.) using a bar coater. After coating so as to have a thickness of 3.0 μm, a hard coat layer was formed by irradiating ultraviolet rays of 400 mJ/cm ² with a high-pressure mercury lamp. Coating solution 1 or 3 was applied on the hard coat layer using a bar coater so that the film thickness after drying was 100 nm, and then under a nitrogen atmosphere such that the oxygen concentration was 800 ppm or less, high pressure was applied. A mercury lamp was used to irradiate ultraviolet rays of 400 mJ/cm ² to form an optical adjustment layer. After coating the obtained coating liquid X1 for forming a low refractive index layer on the optical adjustment layer using a bar coater so that the film thickness after drying becomes 100 nm, the oxygen concentration becomes 500 ppm or less. A low refractive index layer was formed by irradiating ultraviolet rays of 400 mJ/cm ² with a high-pressure mercury lamp in a nitrogen atmosphere to obtain an antireflection film.

[Example 29]
In the same manner as in Example 1, a coating liquid X1 for forming a low refractive index layer was obtained.
As shown in Table 5, a 50 μm thick polyethylene terephthalate (PET) film (“Lumirror UH-13” manufactured by Toray Industries, Inc.) was coated with a hard coat layer forming coating solution 1 (coating solution 1) using a bar coater. was applied so that the film thickness after drying was 3.0 μm, and ultraviolet rays of 400 mJ/cm ² were irradiated with a high-pressure mercury lamp to form a hard coat layer. On the hard coat layer, the obtained low refractive index layer forming coating solution X1 was applied using a bar coater so that the film thickness after drying was 140 nm, and then the oxygen concentration was 500 ppm or less. A low refractive index layer was formed by irradiating ultraviolet rays of 400 mJ/cm ² with a high-pressure mercury lamp in a nitrogen atmosphere to obtain an antireflection film.

[Evaluation items and evaluation methods]
Evaluation methods for the obtained low refractive index layer and antireflection film are as follows. The results are shown in Tables 2-5.

<Measurement of refractive index>
Using "Prism Coupler Model 2010" manufactured by Metricon, the refractive indices of the low refractive index layer, the hard coat layer, and the optical adjustment layer at a wavelength of 594 nm were obtained.

<HZ; measurement of haze value>
The haze value (HZ) of the surface of the low refractive index layer of the produced antireflection film was measured using a "haze meter SH7000" manufactured by Nippon Denshoku Industries Co., Ltd. Incidentally, Δ and ◯ are practically acceptable levels.
[Evaluation criteria]
・○: 1.5% or less ・△: over 1.5% and up to 2.0% ・×: over 2.0%

<SW resistance; scratch resistance>
The scratch resistance of the produced antireflection film was evaluated using a "Gakushin type fastness to rubbing tester" manufactured by Tester Sangyo Co., Ltd. Steel wool #0000 was attached to a friction element (surface area: 1 cm ² ) to which a load of 200 g was attached, and the surface (1 cm×15 cm) of the hard coat layer was reciprocated 10 times. After that, the haze value of the antireflection film was measured and evaluated according to the following criteria.
[Evaluation criteria]
◎: ΔHz is 0.05% or less (very good)
・○: ΔHz is over 0.05% and 0.1% or less (good)
・△: ΔHz is over 0.1% and 0.2% or less (acceptable)
・×: ΔHz exceeds 0.2% (defective)
Here, ΔHz = haze value after scratch test - haze value before scratch test.

<Gauze resistance>
The scratch resistance of the produced antireflection film was evaluated using a "Gakushin type fastness to rubbing tester" manufactured by Tester Sangyo Co., Ltd. A gauze (Iwatsuki gauze, 100% cotton) was attached to a friction element (surface area: 1 cm ² ) to which a load of 500 g was attached, and the surface (1 cm×15 cm) of the hard coat layer was reciprocated 100 times. After that, the haze value of the antireflection film was measured and evaluated according to the following criteria.
[Evaluation criteria]
・○: ΔHz is 0.05% or less (very good)
・ △: ΔHz is over 0.05% and 0.1% or less (good)
・ ×: ΔHz exceeds 0.1% (defective)

<Stain resistance>
The antifouling property was evaluated from the water contact angle results. It can be said that the larger the contact angle, the easier it is to repel water and the less likely it is to get dirty.
For the water contact angle, the contact angle value of the surface of the low refractive index layer of the obtained antireflection film was obtained using a fully automatic contact angle meter DM-701 manufactured by Kyowa Interface Science Co., Ltd.
[Evaluation criteria]
・○: Contact angle is 100° or more (very good)
・△: Contact angle is 90° or more and less than 100° (good)
・×: contact angle is less than 90° (defective)
Incidentally, Δ and ◯ are practically acceptable levels.

<Measurement of luminous reflectance>
According to JIS Z8722, it was measured using a "spectrophotometer U4100" manufactured by Hitachi High-Tech Science Co., Ltd. and a "5-degree specular reflection attachment". The surface of the film opposite to the antireflection layer was scraped with sandpaper, coated with black ink and dried to minimize the influence of light reflection from the back surface, and measurements were made. Incidentally, Δ and ◯ are practically acceptable levels.
[Evaluation criteria]
・ ◎: 0.5% or less ・ ○: 0.5% over 1.0% or less (very good)
・ △: more than 1.0% and 1.5% or less (good)
・ ×: 1.5% exceeded (defective)

As shown in Tables 2 to 5, the low refractive index layer formed using the coating solution for forming a low refractive index layer of the present invention can be either a rigid fiber such as steel wool or a flexible fiber such as gauze. It was also found that an antireflection film having high scratch resistance and excellent antifouling properties can be obtained.

<Silica fine particles>
・ Inorganic oxide fine particles (B-6): MEK-AC-2140 Z (Nissan Chemical Co., Ltd., silica fine particles, particle size (D50) of 20 nm, particle size (D99) of 150 nm)

Claims (8)

Hollow particles (A) having a particle diameter (D ₅₀ ) of 150 nm or less, and inorganic oxide fine particles (B) having a particle diameter (D ₅₀ ) of 10 to 90 nm and a particle diameter (D ₉₉ ) of 150 to 300 nm (where excluding hollow particles (A)) and a polyfunctional (meth)acrylate (C),
A coating liquid for forming a low refractive index layer, containing 0.5 to 15 parts by mass of the inorganic oxide fine particles (B) with respect to 100 parts by mass of the hollow particles (A). 2. The coating liquid for forming a low refractive index layer according to claim 1, further comprising a fluorine-containing (meth)acrylate (D). 3. The low refractive index layer forming method according to claim 2, wherein the content of the fluorine-containing (meth)acrylate (D) is 0.5 to 10% by mass based on 100% by mass of the non-volatile matter in the coating liquid for forming the low refractive index layer. coating liquid. 4. The coating liquid for forming a low refractive index layer according to any one of claims 1 to 3, wherein the polyfunctional (meth)acrylate (C) contains a polyfunctional (meth)acrylate having a silicone chain. A low refractive index layer formed from the coating liquid for forming a low refractive index layer according to any one of claims 1 to 4. 6. The low refractive index layer according to claim 5, wherein the surface has a contact angle with water of 90° or more, and a change in haze of 0.1 or less after 10 reciprocations with a load of 200 g/cm ² in a steel wool test. An antireflection film comprising the low refractive index layer according to claim 5 or 6 on a transparent substrate. 8. The antireflection film according to claim 7, which has a luminous reflectance of 1.5% or less.