JP2010275483A - Surface treatment agent for metal oxide particles, coating agent for forming a hard coat layer, and hard coat film - Google Patents

Abstract

Provided are a surface treatment agent that provides metal oxide particles having excellent dispersibility, and a coating agent that includes the metal oxide particles having excellent dispersibility and provides a hard coat film having improved transparency and scratch resistance. To do.
A surface treatment agent for metal oxide particles comprising a polymerizable compound having a carboxylic acid group in the molecule and four or more ethylenically unsaturated groups per molecule, and (A) an ionizing radiation curable compound. And (B) a hard coat layer forming coating agent comprising metal oxide particles surface-treated with the surface treatment agent.
[Selection figure] None

Description

  The present invention relates to a surface treatment agent for metal oxide particles, a coating agent for forming a hard coat layer, and a hard coat film. More specifically, the present invention provides a surface treatment agent that gives metal oxide particles having excellent dispersibility, and a hard coat film having improved transparency and scratch resistance, including the metal oxide particles having excellent dispersibility. The present invention relates to a coating agent and a hard coat film having the above performance.

In recent years, hard coat films have been used for the purpose of surface protection of various image display devices such as LCD (liquid crystal display), CRT (CRT), PDP (plasma display panel), EL (electroluminescence), or optical discs. Yes.
A touch panel is used as an input device to a portable information terminal. This touch panel is a device for inputting data by directly touching the display screen with a finger, pen, etc. Generally, a transparent conductive thin film such as a tin-doped indium oxide (ITO) film is laminated on one side of a transparent plastic substrate. Touched plastic substrate and display-side transparent substrate with transparent conductive thin film such as ITO film laminated on one side of transparent base material such as glass, facing each transparent conductive thin film through insulating spacer It has an arranged structure. Then, the input is performed by pressing the touch input surface of the touch side plastic substrate (which is the surface opposite to the transparent conductive thin film) with a pen or a finger, and the transparent conductive thin film of the touch side plastic substrate and the display side transparent substrate. The transparent conductive thin film is contacted.

However, in such a touch panel, the touch side surface is damaged by repeating the input operation, that is, by repeatedly contacting the transparent conductive thin film of the touch side plastic substrate and the transparent conductive thin film of the display side transparent substrate. Or the transparent conductive thin film of the touch side plastic substrate (base material film) is worn out, cracks are generated, or further, the touch side plastic substrate is peeled off from the base material. Therefore, in order to solve such a problem, generally, a hard coat layer made of a synthetic resin is provided between the touch side surface and the transparent plastic substrate and the transparent conductive thin film.
In addition, to improve the surface on the touch side, we also propose a polarizing film with an anti-reflective coating on a hard coat layer containing a resin that cures by radiation, etc., and ultrafine titanium oxide that has been surface-treated with a metal oxide. (For example, refer to Patent Document 1).

In such a hard coat layer, in order to improve hard coat performance such as scratch resistance, metal oxide particles such as silica particles are contained in the hard coat layer. In this case, since high transparency is required in each of the above-described applications, the metal oxide particles to be contained are preferably as small as possible.
However, in the coating agent for forming the hard coat layer, when the particle size of the metal oxide particles is reduced (on the nanometer level), aggregation occurs, and as a result, the effect of improving the scratch resistance is not exhibited. Problems such as a decrease in transparency occur. Therefore, in order to suppress the aggregation of the metal oxide particles and improve the dispersibility, a surface treatment agent for the metal oxide particles (for example, see Patent Document 2), a reactive dispersant (for example, see Patent Document 3), An oligomeric dispersant (for example, see Patent Document 4) adsorbed on inorganic particles has been proposed.

JP 2000-171603 A JP 2001-310423 A JP 2007-289943 A JP 2006-225513 A

  The present invention has been made under such circumstances, and includes a surface treatment agent that gives metal oxide particles having further excellent dispersibility, and metal oxide particles having excellent dispersibility, and has transparency and resistance. It is an object of the present invention to provide a coating agent that provides a hard coat film with improved scratch resistance and a hard coat film having the above performance.

  As a result of intensive studies to achieve the above object, the present inventors have found that a polymerizable compound having a carboxylic acid group in the molecule and containing a certain number of ethylenically unsaturated groups as a surface treatment agent. It was found that it can be adapted to the purpose. The present invention has been completed based on such findings.

That is, the present invention
(1) A surface treatment agent for metal oxide particles comprising a polymerizable compound having a carboxylic acid group in the molecule and 4 or more ethylenically unsaturated groups per molecule,
(2) A coating agent for forming a hard coat layer, comprising (A) an ionizing radiation curable compound, and (B) metal oxide particles surface-treated with the surface treating agent according to (1) above. And (3) a hard coat film comprising a hard coat layer made of a cured product by ionizing radiation of the coating agent according to (2) above on a transparent substrate,
Is to provide.

  According to the present invention, a surface treatment agent that provides metal oxide particles having excellent dispersibility, a coating agent that includes the metal oxide particles having excellent dispersibility, and that provides a hard coat film with improved transparency and scratch resistance, And the hard coat film which has said performance can be provided.

First, the surface treatment agent for metal oxide particles of the present invention (hereinafter sometimes simply referred to as “surface treatment agent”) will be described.
[Surface treatment agent]
The surface treatment agent for metal oxide particles of the present invention is characterized by comprising a polymerizable compound having a carboxylic acid group and four or more ethylenically unsaturated groups per molecule.

(Structure of polymerizable compound)
Although the said polymeric compound should just have at least one carboxylic acid group in a molecule | numerator, it is preferable that the number satisfy | fills the below-mentioned acid value. Due to the carboxylic acid group, the polymerizable compound exhibits adsorptivity to the surface of the metal oxide particles and suppresses aggregation of the particles. If the number of carboxylic acid groups is too large (exceeding the upper limit of the acid value described later), cross-linking between particles occurs, and on the contrary, aggregation of particles occurs.
The polymerizable compound further needs to contain 4 or more ethylenically unsaturated groups per molecule together with the carboxylic acid group. By having this ethylenically unsaturated group, the polymerizable compound has a property of being polymerized and cured by irradiation with ionizing radiation. Moreover, by having 4 or more ethylenically unsaturated groups per molecule, the polymerizable compound becomes bulky, and the effect of inhibiting the aggregation of metal oxide particles is increased.
Therefore, when a metal oxide particle surface-treated with this polymerizable compound is contained in a coating agent for forming a hard coat layer, which will be described later, the particle is prevented from agglomeration and sedimentation and is stably and satisfactorily dispersed. When forming the hard coat layer, the polymerizable compound is polymerized and cured by irradiation with ionizing radiation, so that the metal oxide particles are uniformly dispersed in the hard coat layer in a state of almost primary particles. It can exist, and can improve the scratch resistance and transparency of the hard coat layer.

In the polymerizable compound, when the number of ethylenically unsaturated groups is less than 4 per molecule, the dispersion state of the metal oxide particles in the hard coat layer becomes insufficient, and the effect of improving transparency and scratch resistance is achieved. Is hard to be demonstrated.
Further, the upper limit of the number of ethylenically unsaturated groups per molecule is usually about 7, and it is difficult to synthesize more than this.
The ethylenically unsaturated group is not particularly limited as long as it is a group that can be polymerized by irradiation with ionizing radiation, but from the viewpoint of polymerizability, physical properties of a cured product, availability, and the like, a (meth) acryloyl group is Is preferred. The “(meth) acryloyl group” means an acryloyl group and / or a methacryloyl group. The same applies to other similar terms.

(Properties of polymerizable compound)
In the said polymeric compound, it is preferable that an ethylenically unsaturated group equivalent exists in the range of 80-200 g / eq. When the ethylenically unsaturated group equivalent is in the above range, the aggregation suppressing effect on the metal oxide particles is satisfactorily exhibited, and the cured product of the polymerizable compound by ionizing radiation has high hardness. A more preferred ethylenically unsaturated group equivalent is in the range of 90 to 130 g / eq.
The acid value (measured according to JIS K 1557) is preferably in the range of 10 to 50 mgKOH / g. If this acid value is in the above range, cross-linking between the metal oxide particles is difficult to occur, and the particles are appropriately adsorbed on the surface of the particles to effectively suppress aggregation of the particles. A more preferred acid value is in the range of 20-30 mg KOH / g.
Furthermore, the molecular weight is about 320 to 1400, preferably 360 to 910, based on the number of ethylenically unsaturated groups introduced into one molecule and the ethylenically unsaturated group equivalent.

(Production of polymerizable compound)
Since the polymerizable compound has at least one carboxylic acid group in the molecule and four or more ethylenically unsaturated groups, preferably (meth) acryloyl groups per molecule, these groups can be used as starting materials. A monohydric alcohol can be used and introduced by an esterification reaction with the hydroxyl group. In this case, as the raw material polyhydric alcohol, one having 5 or more hydroxyl groups in one molecule can be used. As such polyhydric alcohols, from the viewpoint of availability, triglycerol (OH: 5), tetraglycerol (OH: 6), dipentaerythritol (OH: 6), tripentaerythritol (OH: 8) and sorbitol (OH: 6).

Next, as an example of producing the polymerizable compound using these polyhydric alcohols as raw materials, one hydroxyl group of the polyhydric alcohol is left as a functional group for introducing a carboxylic acid group, and all other hydroxyl groups are A method of introducing a carboxylic acid group into the remaining hydroxyl group after introducing a (meth) acryloyl group which is an ethylenically unsaturated group will be described.
First, the polyhydric alcohol is allowed to react with (meth) acrylic acid, (meth) acrylic acid lower alkyl (methyl, ethyl) ester or (meth) acrylic acid halide by a known method to leave one hydroxyl group. Then, polyhydric alcohol poly (meth) acrylate in which all other hydroxyl groups are esterified is synthesized. As this polyhydric alcohol poly (meth) acrylate, triglycerol tetra (meth) acrylate, tetraglycerol penta (meth) acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol hepta (meth) acrylate, sorbitol penta (meth) ) Acrylate and the like.
Next, polyhydric carboxylic acid is reacted with one hydroxyl group remaining in these polyhydric alcohol poly (meth) acrylates according to a conventionally known method to form a monoester of polyhydric carboxylic acid. Thereby, one or more carboxylic acid groups are introduced into the polyhydric alcohol poly (meth) acrylate.

The polyvalent carboxylic acid is not particularly limited, and any of aliphatic, alicyclic, and aromatic can be used. Examples of the aliphatic polycarboxylic acid include aliphatic dicarboxylic acids having 1 to 4 carbon atoms of alkanediyl groups such as malonic acid, succinic acid, succinic anhydride, glutaric acid, and adipic acid, and butanetetracarboxylic acid. Is mentioned. Examples of the alicyclic polyvalent carboxylic acid include cyclohexane-1,2-dicarboxylic acid or an acid anhydride thereof, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, cyclohexane-1,2, and the like. Examples include 4-tricarboxylic acid or its 1,2-acid anhydride, decalin-2,6-dicarboxylic acid, decalin-2,3-dicarboxylic acid or its acid anhydride. Examples of aromatic polycarboxylic acids include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic acid, trimellitic anhydride, naphthalene-2,6-dicarboxylic acid, naphthalene-2,3-dicarboxylic acid or The acid anhydride etc. are mentioned.
In the present invention, among the polyvalent carboxylic acids, acid anhydrides are preferable from the viewpoint of easy monoesterification reaction of polyvalent carboxylic acids and availability, for example, succinic anhydride, cyclohexane-1,2- Dicarboxylic acid anhydride, cyclohexane-1,2,4-tricarboxylic acid 1,2-acid anhydride, decalin-2,3-dicarboxylic acid anhydride, phthalic anhydride, trimellitic anhydride, naphthalene- An acid anhydride of 2,3-dicarboxylic acid is preferable. Of these, succinic anhydride is preferably used from the viewpoint of the performance of the polymerizable compound obtained as a surface treating agent.

  By reacting the polyhydric alcohol poly (meth) acrylate with succinic anhydride, 3-carboxypropionic acid-modified polyhydric alcohol poly (meth) acrylate, specifically, 3-carboxypropionic acid-modified triglycerol tetra (meta) ) Acrylate, 3-carboxypropionic acid modified tetraglycerol penta (meth) acrylate, 3-carboxypropionic acid modified dipentaerythritol penta (meth) acrylate, 3-carboxypropionic acid modified tripentaerythritol hepta (meth) acrylate, 3-carboxy Propionic acid-modified sorbitol penta (meth) acrylate and the like can be obtained. Among these, as the polymerizable compound, a compound having a (meth) acryloyl group equivalent in the range of 80 to 200 g / eq and an acid value in the range of 10 to 50 mgKOH / g is preferable, particularly performance and availability. From such viewpoints, 3-carboxypropionic acid-modified dipentaerythritol penta (meth) acrylate (polymerizable compound I) having the following structure is preferable.

(R represents a hydrogen atom or a methyl group.)

(Metal oxide particles)
There is no restriction | limiting in particular as metal oxide particle to which the surface treating agent which consists of the said polymeric compound of this invention is applied, According to the function of the hard-coat layer in which this metal oxide particle contains, it selects suitably.
The metal oxide particles preferably have high hardness in order to improve the hard coat performance such as scratch resistance of the hard coat layer. For example, titania (TiO ₂ ) particles, zirconia (ZrO ₂ ) particles, Alumina (Al ₂ O ₃ ) particles or the like can be used. These metal oxide particles may be used individually by 1 type, and may be used in combination of 2 or more types.
Further, when conductive particles are required as metal oxide particles, for example, tin oxide particles, antimony-doped tin oxide (ATO) particles, indium oxide particles, tin-doped indium oxide (ITO) particles, zinc oxide particles, Aluminum doped zinc oxide particles, zinc antimonate particles and the like can be used singly or in combination.
Although there is no restriction | limiting in particular in the shape of the said metal oxide particle, From a viewpoint of improving transparency, a spherical particle is preferable.

(Surface treatment of metal oxide particles)
As a method of surface-treating the metal oxide particles using the surface treatment agent of the present invention described above, for example, the following method can be used.
In the solvent used as needed, 100 parts by mass of the metal oxide particles and the surface treatment agent comprising the aforementioned polymerizable compound are preferably 20 to 100 parts by mass, more preferably 25 to 80 parts by mass. In addition to the solid content concentration of about 1 to 50% by mass, preferably 20 to 40% by mass, surface treatment and dispersion of the metal oxide particles are performed, and the surface treatment agent and the surface-treated metal oxide are added. A dispersion containing particles is prepared.
The dispersion method is not particularly limited, and a conventionally known method can be employed. For example, dispersion using a paint shaker, a roll mill, a ball mill, an attritor, a sand mill, a bead mill or the like, or ultrasonic dispersion may be used. In addition, when using the obtained dispersion for a coating agent for forming a hard coat layer, a dispersion medium such as glass beads or zirconia beads is used from the viewpoint of coating properties, paint stability, and transparency of a cured film. Dispersion with a bead mill is preferred. The bead diameter is not particularly limited, but is usually about 0.05 to 2 mm, preferably 0.05 to 0.5 mm.

The solvent is preferably a hydrophobic solvent from the viewpoint that the surface treatment agent is effectively adsorbed on the surface of the metal oxide particles and suppresses aggregation of the particles. Examples of the hydrophobic solvent include aliphatic hydrocarbons such as hexane and cyclohexane, aromatic hydrocarbons such as benzene, toluene and xylene, esters such as propyl acetate and butyl acetate, halogenations such as methylene chloride, chloroform and carbon tetrachloride. Examples include hydrocarbons, ketones such as methyl isobutyl ketone, cyclohexanone, and isophorone. These solvent may be used individually by 1 type, and may be used in combination of 2 or more type.
Moreover, about the ratio of the surface treating agent of this invention, and a metal oxide particle, if a surface treating agent is a ratio of 20-100 mass parts with respect to 100 mass parts of metal oxide particles, this metal oxide particle The anti-aggregation effect is exhibited well. Furthermore, if the solid content concentration is 1 to 50% by mass, surface treatment and dispersion treatment of metal oxide particles can be effectively performed.

In the dispersion containing the surface treatment agent of the present invention and the surface-treated metal oxide particles prepared as described above, the average particle diameter of the metal oxide particles is preferably 1 to 200 nm. 2 to 100 nm is more preferable. It is difficult to obtain metal oxide particles having an average particle diameter of less than 1 nm. On the other hand, when the average particle diameter exceeds 200 nm, the hard coat layer formed using the dispersion as a coating agent for forming a hard coat layer improves the desired transparency. It is difficult to obtain the effect, and the storage stability of the dispersion tends to decrease.
In addition, the average particle diameter of the metal oxide particles in the dispersion is a value measured by a dynamic light scattering method.

Next, the coating agent for forming a hard coat layer of the present invention will be described.
[Coating agent for hard coat layer formation]
The coating agent for forming a hard coat layer of the present invention (hereinafter sometimes simply referred to as “coating agent”) is (A) an ionizing radiation curable compound, and (B) the surface treatment agent of the present invention described above. It contains treated metal oxide particles.

((A) ionizing radiation curable compound)
In the coating agent of the present invention, the ionizing radiation curable compound used as the component (A) is a compound having energy quanta in an electromagnetic wave or a charged particle beam, that is, crosslinked by irradiating ultraviolet rays or electron beams. Refers to a compound that cures.
In the present invention, a polyfunctional (meth) acrylate monomer and / or (meth) acrylate oligomer can be used as the ionizing radiation curable compound.

  Examples of multifunctional (meth) acrylate monomers include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol. Di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone-modified dicyclopentanyl di (meth) acrylate, ethylene oxide-modified di (meth) phosphate Acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaery Litol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, propionic acid modified dipentaerythritol penta (meth) acrylate, dipentaerythritol Examples include hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. These polyfunctional (meth) acrylate monomers may be used alone or in combination of two or more.

On the other hand, examples of the (meth) acrylate oligomer include polyester acrylate, epoxy acrylate, urethane acrylate, and polyol acrylate.
Here, examples of the polyester acrylate oligomer include esterification of hydroxyl groups of a polyester oligomer having hydroxyl groups at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid, It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to a carboxylic acid with (meth) acrylic acid. The epoxy acrylate oligomer can be obtained, for example, by esterification by a reaction between an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolak type epoxy resin and (meth) acrylic acid.
The urethane acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by reaction of polyether polyol or polyester polyol with polyisocyanate by reaction with (meth) acrylic acid.
The polyol acrylate oligomer can be obtained by esterifying the hydroxyl group of polyether polyol by reaction with (meth) acrylic acid. These (meth) acrylate oligomers may be used singly or in combination of two or more, and may be used in combination with the above-mentioned polyfunctional (meth) acrylate monomers.

((B) Surface-treated metal oxide particles)
In the coating agent of this invention, the metal oxide particle surface-treated with the surface treating agent of this invention is used as (B) component. The metal oxide particles and the surface treatment method thereof are as described above.
In the present invention, the surface-treated metal oxide particles of the component (B) include the surface-treating agent of the present invention and the surface-treated metal oxide particles that are homogeneously dispersed, and are subjected to metal oxidation. A dispersion in which the average particle size of the product particles is preferably in the range of 1 to 200 nm, more preferably 2 to 100 nm is used.
In the coating agent of the present invention, the content of the metal oxide particles in the solid content is preferably 10 to 80% by mass from the viewpoint of the balance of scratch resistance and transparency of the hard coat layer to be formed. It is more preferable that it is 20-60 mass%.

(Photopolymerization initiator)
If desired, the coating agent of the present invention may contain a photopolymerization initiator. As this photopolymerization initiator, for example, benzoins, acetophenones, benzophenones, ketals, anthraquinones, thioxanthones, phosphine oxides, and the like can be used.
Specifically, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy 2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propane -1-one, 4- (2-hydroxyethoxy) phenyl-2 (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethylaminobenzophenone, dichlorobenzene Nzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiarybutylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4- Examples include diethyl thioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, 2,4,6-trimethylbenzoyl diphenyl phosphine oxide, p-dimethylaminobenzoate, and the like.
These may be used singly or in combination of two or more, and the blending amount is usually in the range of 0.2 to 10 parts by mass with respect to 100 parts by mass of the total ionizing radiation curable compound. Chosen by

In the coating agent of the present invention, in addition to the components (A) and (B) and the photopolymerization initiator used as desired, various additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, and an antistatic agent are used. An agent, a leveling agent, an antifoaming agent, etc. can be contained.
Moreover, the coating agent of this invention can be diluted with an organic solvent so that it may become a density | concentration and viscosity suitable for coating. The organic solvent used at this time is preferably a hydrophobic solvent as described above.

Next, the hard coat film of the present invention will be described.
[Hard coat film]
The hard coat film of the present invention has a hard coat layer made of a cured product of the above-described coating agent of the present invention by ionizing radiation on a transparent substrate.

(Transparent substrate)
Although there is no restriction | limiting in particular in the transparent base material used in the hard coat film of this invention, It can select from the well-known plastic film conventionally used as a base material of the hard coat film for optics, and can use it. . For example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyester film such as polycarbonate, polyethylene film, polypropylene film, cellophane, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film , Polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, fluororesin film, polyamide film, acrylic Resin film, polyurethane resin film It can be used norbornene polymer film, cycloolefin polymer films, cyclic conjugated diene polymer film, a vinyl alicyclic hydrocarbon polymer film.
Among these, a polyethylene terephthalate film, a polycarbonate film, a norbornene polymer film, and the like are preferably used from the viewpoint of performance as a substrate.

There is no restriction | limiting in particular as thickness of the said plastic film, Although it selects suitably according to the use of a hard coat film, Usually, about 20-300 micrometers, Preferably it is the range of 50-250 micrometers.
When using a plastic film as the transparent substrate, for the purpose of improving the adhesion with the layer provided on the surface, one or both sides may be subjected to a surface treatment by a primer treatment, an oxidation method, an unevenness method, or the like as desired. Can do. Examples of the oxidation method include corona discharge treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, ozone / ultraviolet treatment, and examples of the unevenness method include a sand blast method and a solvent treatment method. . These surface treatment methods are appropriately selected according to the type of the base film, but generally, the corona discharge treatment method is preferably used from the viewpoints of effects and operability.

(Formation of hard coat layer)
In the hard coat film of the present invention, on the transparent substrate, the coating agent of the present invention described above is applied to provide a coating layer, and this is irradiated with ionizing radiation to be crosslinked and cured. Then, a hard coat layer is formed.
There is no restriction | limiting in particular in the coating method of the said coating agent, A conventionally well-known method can be used. For example, the coating can be performed using a bar coating method, a knife coating method, a Meyer bar coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like. When the coating agent to be used contains an organic solvent, the solvent is preferably removed by drying after coating.

In this way, the coating layer provided on the transparent substrate is irradiated with ionizing radiation such as ultraviolet rays or electron beams to crosslink and cure the coating layer.
UV irradiation, for example, a high pressure mercury lamp, a fusion Co. H lamps, obtained by a xenon lamp, irradiation dose is usually 100 to 500 mJ / cm ² or so. On the other hand, in the case of electron beam irradiation, the electron beam is obtained by an electron beam accelerator or the like, and the irradiation amount is usually about 150 to 350 kV. In the case of using an electron beam, it can be cured without adding a polymerization initiator to form a hard coat layer.
The thickness of the hard coat layer thus formed is preferably in the range of 1 to 100 μm. If the thickness of the hard coat layer is in the above range, good scratch resistance can be obtained and the occurrence of cracks can be suppressed. A more preferable thickness is in the range of 5 to 30 μm.

(Properties of hard coat film)
In the hard coat film of the present invention, the pencil hardness (measured according to JIS K 5400) of the hard coat layer surface can be H or higher, preferably 2H or higher. Further, the total light transmittance measured according to JIS K 7136 can be 50% or more, preferably 85% or more, and the haze value can be 5.0% or less, preferably 1.0% or less.

In the hard coat layer of the hard coat film of the present invention, an uneven shape can be formed on the surface for the purpose of imparting antiglare properties. In order to form the concavo-convex shape, for example, after coating the coating agent of the present invention, after laminating a shaped film having a concavo-convex shape on the surface of the uncured layer, the uncured layer is cured by ionizing radiation, A method of peeling the shaped film can be used.
The hard coat layer may be provided with an antireflection layer such as a siloxane-based film or a fluorine-based film for the purpose of imparting antireflection properties. In this case, the thickness of the antireflection layer is suitably about 0.05 to 1 μm. By providing this antireflection layer, the surface reflectance due to sunlight, fluorescent lamps and the like is lowered, and visibility is improved.

(Adhesive layer)
In the hard coat film of the present invention, an adhesive layer for adhering to an adherend such as a polarizing plate of a liquid crystal display can be formed on the surface of the transparent substrate opposite to the hard coat layer. . As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, for example, an acrylic pressure-sensitive adhesive or a silicone pressure-sensitive adhesive suitable for optical applications is preferably used. The thickness of this pressure-sensitive adhesive layer is usually 5 to 100 μm, preferably 10 to 60 μm.
Furthermore, a release sheet can be provided on the pressure-sensitive adhesive layer as necessary. Examples of the release sheet include those obtained by applying a release agent such as a silicone resin to various plastic films such as polyethylene terephthalate and polypropylene. Although there is no restriction | limiting in particular about the thickness of this peeling sheet, Usually, it is about 20-150 micrometers.

(Use)
The hard coat film of the present invention has good scratch resistance and transparency, and is suitably used as a surface protective member for imparting scratch resistance performance to displays such as CRT, LCD, and PDP. It is suitable for polarizing plate application in the above.
Moreover, it can provide suitably between the touch side surface in a touch panel, or between a transparent plastic base material and a transparent conductive thin film.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, the average particle diameter and dispersibility of the metal oxide particles in the dispersion obtained in each example and the performance of the hard coat film obtained in each example were measured according to the following methods.
(1) The average particle diameter of the metal oxide particles in the dispersion was measured by Microtrac (dynamic light scattering method manufactured by Nikkiso Co.).
(2) Dispersibility of metal oxide particles in dispersion The presence or absence of sedimentation after the dispersion was allowed to stand for 24 hours and the presence or absence of fluidity were visually evaluated. The evaluation criteria are as follows. Here, “with sedimentation” indicates a state where the solvent and the dispersion are separated, and “without sedimentation” indicates a state where the solvent and the dispersion are not separated. Further, “fluidity” means that the liquid level flows when the container is tilted, and “no fluidity” means that the liquid level does not flow even when the container is tilted.
○: No sedimentation and fluidity ×: There is sedimentation or no fluidity

<Performance of hard coat film>
(3) Total light transmittance and haze value Using a haze meter [Nippon Denshoku Industries Co., Ltd. make, model name "NDH-2000], the total light transmittance and haze value were measured based on JISK7136.
(4) Pencil Hardness Based on JIS K 5400, pencil hardness was measured using a pencil scratch coating film hardness tester [manufactured by Toyo Seiki Co., Ltd.].
Moreover, polymeric compound AD used in each example has the following structure.

Example 1
(1) Preparation of dispersion 15 parts by mass of polymerizable compound A [manufactured by Toagosei Co., Ltd., trade name “M-520”, acryloyl group equivalent 100 g / eq, acid value 25 mg KOH / g], alumina having an average primary particle size of 12 nm Dispersions were prepared by the method shown below using 30 parts by mass of particles [manufactured by Aerosil Co., Ltd., trade name “AluC”] and 55 parts by mass of methyl isobutyl ketone as a hydrophobic solvent.
The polymerizable compound, alumina fine particles, and a hydrophobic solvent were mixed, and further dispersed with a paint shaker using zirconia beads.
The average particle diameter of the alumina particles in the obtained dispersion was 65 nm, and the evaluation of dispersibility was ○.
(2) Production of Hard Coat Film A hard coat film was produced by the method shown below using the dispersion prepared in (1) above.
86% by mass of the dispersion prepared in (1), 13% by mass of dipentaerythritol hexaacrylate, and 1% by mass of Irgacure 184 were mixed, and a 40 μm cellulose triacetate film was used as the light-transmitting resin substrate. It apply | coated so that it might become dry weight 15g / m < ² > on a material. It dried at 70 degreeC for 30 ^second, and irradiated the ultraviolet-ray 200mJ / cm < ² >, and produced the hard coat film of Example 1. FIG.
Various characteristics are shown in Table 1.

Comparative Example 1
A dispersion was prepared in the same manner as in Example 1 except that the polymerizable compound B was used in place of the polymerizable compound A in Example 1. A good dispersion could not be obtained.

Comparative Example 2
A dispersion was prepared in the same manner as in Example 1 except that the polymerizable compound C was used in place of the polymerizable compound A in Example 1, and a hard coat film was produced. Various characteristics are shown in Table 1.

Comparative Example 3
A dispersion was prepared in the same manner as in Example 1 except that the polymerizable compound D was used in place of the polymerizable compound A in Example 1. A good dispersion could not be obtained.

  Since the surface treatment agent for metal oxide particles according to the present invention effectively suppresses aggregation of the metal oxide particles, the metal oxide particles treated with the surface treatment agent are applied to the hard coat layer forming coating agent. When used, the particles exhibit stable and good dispersibility and can provide a hard coat film with improved transparency and scratch resistance.

Claims (10)

  A surface treatment agent for metal oxide particles, comprising a polymerizable compound having a carboxylic acid group in its molecule and four or more ethylenically unsaturated groups per molecule.   The surface treatment agent for metal oxide particles according to claim 1, wherein the polymerizable compound has an ethylenically unsaturated group equivalent of 80 to 200 g / eq.   The surface treatment agent for metal oxide particles according to claim 1 or 2, wherein the polymerizable compound has an acid value of 10 to 50 mgKOH / g.   The surface treatment agent for metal oxide particles according to any one of claims 1 to 3, wherein the metal oxide particles are at least one selected from titania particles, zirconia particles, and alumina particles.   A coating agent for forming a hard coat layer, comprising (A) an ionizing radiation curable compound, and (B) a metal oxide particle surface-treated with the surface treating agent according to claim 1. .   The coating agent for forming a hard coat layer according to claim 5, wherein the component (A) is a polyfunctional (meth) acrylate monomer and / or a (meth) acrylate oligomer.   The hard coat layer according to claim 5 or 6, wherein the component (B) has an average particle diameter of 1 to 200 nm obtained by surface-treating 100 parts by mass of metal oxide particles with 20 to 100 parts by mass of a surface treatment agent. Forming coating agent.   Content of the metal oxide particle in solid content of a coating agent is 10-80 mass%, The coating agent for hard-coat layer formation in any one of Claims 5-7.   A hard coat film comprising a hard coat layer made of a cured product of the coating agent according to claim 5 by ionizing radiation on a transparent substrate.   The hard coat film according to claim 9, wherein the thickness of the hard coat layer is 1 to 100 μm.