JP5899663B2 - Hard coat layer composition, hard coat film, polarizing plate and image display device - Google Patents

Description

The present invention relates to a composition for a hard coat layer, a hard coat film, a polarizing plate, and an image display device.

In an image display device such as a cathode ray tube display device (CRT), a liquid crystal display (LCD), a plasma display (PDP), an electroluminescence display (ELD), an electronic paper, etc., an optical laminate for preventing reflection is generally provided on the outermost surface. Is provided. Such an anti-reflection optical laminate suppresses the reflection of an image or reduces the reflectance due to light scattering or interference.

As the optical laminate, a hard coat film in which a hard coat layer is formed on the surface of a transparent substrate is known.
Such a hard coat film is manufactured in a long length from the viewpoint of low cost and mass production, and then wound on a roll, but when the surface of the hard coat film is smooth, when the hard coat film is fed from the roll, Adjacent hard coat films stick to each other, causing a phenomenon called blocking, resulting in a decrease in yield.

For such a blocking problem, for example, a method of adding a slippery agent to the hard coat layer and imparting a slipperiness (slipperiness) to the hard coat layer surface by the slippery agent present on the hard coat layer surface Is known (see, for example, Patent Document 1).
However, in the conventional method of adding a lubricant, since the lubricant is uniformly dispersed in the hard coat layer, it is necessary to increase the amount of addition in order to obtain sufficient slipperiness, resulting in a high cost. There is also a problem that the transparency of the hard coat layer is impaired.

Also known is a method of imparting easy lubricity to the hard coat layer by adding a lubricant and a leveling agent to the hard coat layer.
The leveling agent added to such a hard coat layer, for example, C8 telomer (perfluorooctyl group (C 8 _F 17 _-)) fluorine-based leveling agent is known (e.g., see Patent Document 2 ).
However, in recent years, a higher level of anti-blocking property has been demanded, and the conventional hard coat film combined with a leveling agent cannot satisfy the recent high level of anti-blocking property.
Furthermore, C8 telomer is a substance that is concerned about the environmental impact of the perflurooctanoic acid produced in the production process and the influence on the human body, and a heart coat film using a material with less environmental impact is required. ing.

JP 2000-249815 A JP 2010-241919

In view of the present situation, the present invention provides a hard coat layer composition capable of forming a hard coat layer having excellent anti-blocking performance and leveling performance, and a hard coat film formed using the hard coat layer composition An object of the present invention is to provide a polarizing plate and an image display device.

As a result of intensive studies, the present inventors have found that a hard coat layer composition containing silica fine particles and a fluorine-based leveling agent composed of a specific monomer composition has a predetermined content when cured to form a hard coat layer. In addition to hard coat properties, it was found that extremely excellent blocking properties can be exhibited, and the present invention has been completed.

That is, this invention is a composition for hard-coat layers containing a leveling agent, a silica fine particle, and binder resin, Comprising: The said leveling agent is polypropylene glycol monoacrylate, polyethyleneglycol monoacrylate, and 2- ( A fluoro-leveling agent having a monomer composition of perfluorohexyl) ethyl acrylate, and the binder resin contains pentaerythritol tri (meth) acrylate in the binder resin component in a solid content of 15 to 35% by mass , Content of the said silica fine particle is 1-4 mass parts with respect to 100 mass parts of binder resin solid content , It is a composition for hard-coat layers characterized by the above-mentioned .

Also, the fluorine atom content in the fluorine-based leveling agent is preferably a 7-34% by weight.
Moreover, it is preferable that the weight average molecular weights of the said fluorine-type leveling agent are 11000-25000.
Moreover, it is preferable that the composition for hard-coat layers of this invention contains 5-60 mass parts of said fluorine-type leveling agents with respect to 100 mass parts of said silica fine particles.

The present invention also has a light transmissive substrate and a hard coat layer, and the hard coat layer is a hard coat film comprising a cured product of the composition for a hard coat layer of the present invention.
Moreover, this invention is a polarizing plate provided with a polarizing element, Comprising: It is a polarizing plate characterized by providing the above-mentioned hard coat film on the surface of the said polarizing element.
Furthermore, this invention is also an image display apparatus provided with the above-mentioned hard coat film or the above-mentioned polarizing plate on the outermost surface.
Hereinafter, the present invention will be described in detail.

The composition for hard coat layers of the present invention contains a leveling agent, silica fine particles, and a binder resin.
The leveling agent contains a fluorine-based leveling agent having a monomer composition of polypropylene glycol monoacrylate, polyethylene glycol monoacrylate, and 2- (perfluorohexyl) ethyl acrylate.
When the hard coat layer is formed by using the hard coat layer composition of the present invention, the above-mentioned fluorine-based leveling agent has an interaction with the binder resin contained in the hard coat layer composition of the present invention. It is unevenly distributed in the upper part of the coat layer (near the surface opposite to the light-transmitting substrate). As a result, according to the composition for hard coat layers of the present invention, a hard coat layer having good flatness can be formed, and a hard coat film excellent in leveling performance can be obtained.
Moreover, since the said fluorine-type leveling agent contains a polypropylene glycol monoacrylate and a polyethyleneglycol monoacrylate as a monomer composition, a certain amount of hydrophilicity is ensured. When a hard coat layer is formed using the composition for a hard coat layer of the present invention, silica fine particles are attracted and the silica fine particles are unevenly distributed in the upper layer portion of the hard coat layer. As a result, according to the composition for hard coat layers of the present invention, a hard coat film having excellent anti-blocking performance can be obtained.
On the other hand, in the conventional hard coat composition containing a conventional leveling agent having a monomer composition different from that of the above-mentioned fluorine-based leveling agent and silica fine particles, the leveling agent is selected due to the compatibility with the hydrophilic silica fine particles. Even if unevenly distributed in the upper layer portion of the hard coat layer, the leveling agent has insufficient hydrophilicity, so that the silica fine particles are not attracted, and as a result, the silica fine particles are uniformly dispersed in the hard coat layer. It is considered that the anti-blocking performance of the coat film is insufficient.
That is, in order to impart excellent leveling performance and blocking performance to the hard coat film, it is necessary that the leveling agent added to the hard coat layer composition has a certain degree of hydrophilicity.

In the composition for a hard coat layer of the present invention, the polypropylene glycol monoacrylate is preferably 10 to 50% by mass in the monomer composition of the fluorine leveling agent. When the amount is less than 10% by mass, the hydrophilic level of the upper layer portion of the hard coat layer due to the fluorine leveling agent is reduced, and the uneven distribution of silica fine particles is insufficient, resulting in anti-blocking performance when a hard coat film is obtained. It may be insufficient. On the other hand, if it exceeds 50% by mass, the fluorine atom content of the fluorine leveling agent is decreased, and the leveling performance when used as a hard coat film may be insufficient.

Moreover, it is preferable that the said polyethylene glycol monoacrylate is 10-50 mass% in the monomer composition of the said fluorine-type leveling agent. When the content is less than 10% by mass, the hydrophilicity of the fluorine-based leveling agent is lowered, and the uneven distribution of silica fine particles is insufficient, whereby the anti-blocking performance may be insufficient when a hard coat film is obtained. On the other hand, if it exceeds 50% by mass, the fluorine atom content of the fluorine leveling agent is decreased, and the leveling performance when used as a hard coat film may be insufficient.

Moreover, it is preferable that the said 2- (perfluorohexyl) ethylacrylate is 10-50 mass% in the monomer composition of the said fluorine-type leveling agent. If it is less than 10% by mass, the fluorine atom content of the fluorine-based leveling agent is decreased, and the leveling performance of the hard coat film may be insufficient. On the other hand, when it exceeds 50% by mass, the hydrophilicity of the fluorine-based leveling agent is lowered, the uneven distribution of silica fine particles is insufficient, and the anti-blocking performance may be insufficient when a hard coat film is obtained.

The fluorine-based leveling agent composed of the monomer composition described above preferably has a fluorine atom content of 7 to 34% by mass. If it is less than 7% by mass, the leveling performance may be insufficient when a hard coat film is formed. On the other hand, when it exceeds 34 mass%, when it is set as a hard coat film, blocking performance may become inadequate. The minimum with said more preferable fluorine atom content rate is 10 mass%, and a more preferable upper limit is 30 mass%.

The fluorine leveling agent preferably has a weight average molecular weight of 11,000 to 25,000. If it is less than 11000, the silica fine particles may not be attracted sufficiently, and if it exceeds 25000, sufficient leveling performance may not be obtained. The minimum with said more preferable weight average molecular weight is 13000, and a more preferable upper limit is 20,000.
The weight average molecular weight of the fluorine leveling agent is a value obtained by a gel permeation chromatography method (GPC method).

The hard coat layer composition of the present invention preferably contains only the above-described fluorine leveling agent as the leveling agent, but may contain other leveling agents as long as the effects of the present invention are not impaired. Good.
As said other leveling agent, well-known things, such as a fluorine-type leveling agent different from the monomer composition mentioned above, a silicone type leveling agent, an acrylic leveling agent, can be mentioned, for example.

In the composition for hard coat layers of the present invention, it is preferable to contain 5 to 60 parts by mass of the fluorine leveling agent described above with respect to 100 parts by mass of silica fine particles to be described later, and a more preferable lower limit is 7 parts by mass. A preferred upper limit is 50 parts by mass. When it is less than 5 parts by mass, the optical properties may be inferior when it is a hard coat film, and when it exceeds 60 parts by mass, the optical properties are inferior when it is a hard coat film, or sufficient anti-blocking performance is obtained. It may not be possible.

The composition for hard coat layers of the present invention contains silica fine particles.
The silica fine particles are a material that functions as an antiblocking agent (easily slippery), and suitable antiblocking performance can be obtained when a hard coat film is formed by containing the silica fine particles.

Examples of the silica fine particles include particles having no reactive group and an average primary particle size of 100 to 600 nm. If it is less than 100 nm, the hard coat film formed using the composition for hard coat layer of the present invention may not exhibit anti-blocking properties. If it exceeds 600 nm, the haze of the hard coat film may be increased. The average primary particle size is more preferably 100 to 350 nm.
The average primary particle size is a value obtained by measuring with a laser diffraction scattering method particle size distribution measuring apparatus in a 5% by weight dispersion of methyl isobutyl ketone. The average primary particle size of the silica fine particles can also be calculated as an average value of the diameters of the silica fine particles measured by microscopic observation such as SEM when a hard coat film is used.

It is preferable that content of the said silica fine particle is 1-4 mass parts with respect to 100 mass parts of resin solid content of the composition for hard-coat layers of this invention. If it is less than 1 part by mass, the hard coat film formed using the composition for hard coat layer of the present invention may not exhibit anti-blocking properties. When the amount exceeds 4 parts by mass, the optical properties are deteriorated such as an increase in the haze of the hard coat film formed using the composition for hard coat layers of the present invention, and the dispersibility is remarkably deteriorated. As a result, there is a possibility that it may lead to defects in the appearance of the hard coat film surface and an increase in haze.

The composition for hard coats of the present invention contains a binder resin.
The binder resin is preferably transparent, for example, an ionizing radiation curable resin, an ionizing radiation curable resin and a solvent-drying resin (thermoplastic resin, etc.) that are cured by ultraviolet rays or an electron beam. It is possible to use a mixture with a resin or a thermosetting resin by simply drying the solvent added to adjust the solid content. More preferred is an ionizing radiation curable resin. In the present specification, “resin” is a concept including resin components such as monomers and oligomers.

Examples of the ionizing radiation curable resin include compounds having one or more unsaturated bonds such as compounds having an acrylate functional group. Examples of the compound having one unsaturated bond include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone and the like. Examples of the compound having two or more unsaturated bonds include polymethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri ( (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and the like, and polyfunctional compounds obtained by modifying these with ethylene oxide (EO), Or the reaction product (For example, poly (meth) acrylate ester of polyhydric alcohol) etc., such as the said polyfunctional compound and (meth) acrylate, etc. can be mentioned. In the present specification, “(meth) acrylate” refers to methacrylate and acrylate.

In addition to the above compounds, relatively low molecular weight polyester resins having unsaturated double bonds, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. It can be used as an ionizing radiation curable resin.

The ionizing radiation curable resin can be used in combination with a solvent-drying resin. By using the solvent-drying resin in combination, film defects on the coated surface can be effectively prevented. The solvent-drying resin that can be used in combination with the ionizing radiation curable resin is not particularly limited, and a thermoplastic resin can be generally used.
The thermoplastic resin is not particularly limited. For example, a styrene resin, a (meth) acrylic resin, a vinyl acetate resin, a vinyl ether resin, a halogen-containing resin, an alicyclic olefin resin, a polycarbonate resin, or a polyester resin. Examples thereof include resins, polyamide-based resins, cellulose derivatives, silicone-based resins, rubbers, and elastomers. The thermoplastic resin is preferably amorphous and soluble in an organic solvent (particularly a common solvent capable of dissolving a plurality of polymers and curable compounds). In particular, from the viewpoints of film forming properties, transparency and weather resistance, styrene resins, (meth) acrylic resins, alicyclic olefin resins, polyester resins, cellulose derivatives (cellulose esters, etc.) and the like are preferable.

Thermosetting resins that can be used as the binder resin include phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine-urea cocondensation resin. , Silicon resin, polysiloxane resin, and the like.
In the hard coat layer composition of the present invention, the binder resin may be a commercially available one. For example, Beamset DT3 (a mixture of acrylate monomer, acrylate acrylate oligomer, acrylate acrylate polymer, Arakawa Chemical) Manufactured by Kogyo Co., Ltd.).

In the hard coat layer composition of the present invention, the binder resin preferably contains a urethane (meth) acrylate having an isocyanuric skeleton. By containing the urethane (meth) acrylate having the above isocyanuric skeleton, the hard coat film formed using the composition for a hard coat layer of the present invention has high hardness and excellent restorability. it can.
Here, the “high hardness” specifically means “3H” or higher in a pencil hardness test defined by JIS K5600-5-4 (1999).

Examples of the urethane (meth) acrylate having an isocyanuric skeleton include urethane (meth) acrylates in which a polyfunctional monomer is reacted with an isocyanate group at the end of an isocyanurate composed of diisocyanate.

Examples of the polyfunctional monomer include pentaerythritol tri (meth) acrylate, dipentaerythritol pentaacrylate (DPPA), and dipentaerythritol tetra (meth) acrylate.

The urethane (meth) acrylate having the isocyanuric skeleton preferably has 9 or more functional groups. If the number of functional groups is less than 9, sufficient hardness may not be obtained. The number of functional groups is more preferably 12 or more, and still more preferably 15.

The urethane (meth) acrylate having the isocyanuric skeleton preferably has a weight average molecular weight of 1500 to 3000.
If it is less than 1500, sufficient hardness may not be obtained. If it exceeds 3000, the viscosity of the composition for a hard coat layer of the present invention may increase, making coating difficult, or inhibiting the curing reaction of the formed hard coat layer, which may result in insufficient hardness. .
The weight average molecular weight is more preferably 1800-2500.
In addition, the said weight average molecular weight is the value calculated | required in polystyrene conversion by the gel permeation chromatography (GPC) method.

As the urethane (meth) acrylate having the above isocyanuric skeleton, among them, dipentaerythritol pentaacrylate (DPPA) is added to three terminal isocyanates of isocyanurate in which an isocyanuric skeleton is formed with a trimer of hexamethylene diisocyanate (HDI). Urethane acrylate obtained by reacting is preferred. Such a urethane acrylate has a large number of functional groups, has a certain size in molecular weight, and further has an isocyanuric skeleton in the skeleton, so that it can achieve high hardness and has elasticity as a characteristic of the urethane acrylate, for example, Also, restoration properties such as recovery of surface dents by a pencil hardness test of the hard coat film can be realized.

The content of the urethane (meth) acrylate having the isocyanuric skeleton is preferably 30 to 50% by mass in solid content in the binder resin component of the hard coat layer composition. If it is less than 30% by mass, sufficient hardness may not be obtained. If it exceeds 50% by mass, curling of the hard coat film tends to occur. As for the said content, it is more preferable that it is 35-50 mass%.
The curl of the above hard coat film is a shrinkage caused by the UV curing reaction during the formation of the hard coat layer, and the paint film shrinks. Therefore, the stress difference between the paint film (hard coat layer) and the substrate Is a phenomenon in which the film curls on the coating film side.

When the urethane resin (meth) acrylate having the isocyanuric skeleton is contained as the binder resin, it is preferable to further contain pentaerythritol tri (meth) acrylate.
By containing pentaerythritol tri (meth) acrylate, when hard coat films are formed, blocking such that the hard coat films adhere to each other can be more suitably prevented. In addition, curling of the hard coat film can be suitably prevented.

It is preferable that content of the said pentaerythritol tri (meth) acrylate is 15-35 mass% in solid content in the said binder resin component. If the amount is less than 15% by mass, sufficient hardness may not be obtained. If the amount exceeds 35% by mass, curling or blocking may occur when a hard coat film is formed. The content is more preferably 20 to 35% by mass.

The hard coat layer composition preferably further contains a urethane (meth) acrylate having a functional group number of 6 or less as a binder resin.
In addition to the urethane (meth) acrylate having the above-mentioned isocyanuric skeleton, by using urethane (meth) acrylate having a relatively small number of functional groups, curl when maintaining a high pencil hardness and making it a hard coat film Can be prevented.
The urethane (meth) acrylate having 6 or less functional groups is a urethane (meth) acrylate composed of hexamethylene diisocyanate (HDI) and / or isophorone diisocyanate (IPDI), and is a polyfunctional acrylate monomer having 2 to 3 functional groups. It is preferable that this is added.

The content of the urethane (meth) acrylate having 6 or less functional groups is preferably 15 to 35% by mass in solid content in the binder resin component of the hard coat layer composition. If it is less than 15% by mass, curling may occur when a hard coat film is formed. If it exceeds 35 mass%, sufficient hardness may not be obtained.

As the binder resin, it is preferable to contain a (meth) acrylic polymer in addition to the resin component described above. By containing the (meth) acrylic polymer in addition to the urethane (meth) acrylate having the isocyanuric skeleton, curling and damage of the hard coat film can be prevented.
The above-mentioned damage means heat generation due to an ultraviolet curing reaction at the time of forming a hard coat layer, rapid heating due to the heat generation, and rapid cooling due to the end of ultraviolet irradiation at a stretch. And the substrate undulates in the direction of flow.

The (meth) acrylic polymer preferably has a weight average molecular weight of 10,000 to 30,000.
If the weight average molecular weight is less than 10,000, sufficient hardness may not be obtained. If it exceeds 30,000, the coating film adhesion may be reduced, the viscosity of the hard coat layer composition may be increased, the coated surface may be deteriorated, and handling may be deteriorated. The lower limit of the weight average molecular weight is preferably 10,000, and the upper limit is preferably 20,000.
The weight average molecular weight is a value obtained by a gel permeation chromatography method (GPC method).

The (meth) acrylic polymer has an acrylic double bond equivalent of 200 to 300. If the acrylic double bond equivalent is less than 200, it is difficult to synthesize, and the glass transition temperature is lowered. When it exceeds 300, there are few double bonds, and the hardness and scratch resistance of the hard coat layer obtained by curing are lowered.
The lower limit of the acrylic double bond equivalent is preferably 210, and the upper limit is preferably 270.
The acrylic double bond equivalent is a value obtained from the double bond amount and weight average molecular weight calculated from the blended monomers.

The (meth) acrylic polymer preferably has a ratio of the weight average molecular weight to the acrylic double bond equivalent (weight average molecular weight / acrylic double bond equivalent) of 50 to 80.
If the ratio is less than 50, the hardness and scratch resistance may deteriorate. If it exceeds 80, the adhesion may be deteriorated.
The lower limit of the ratio is 50, and the upper limit is more preferably 70.

The (meth) acrylic polymer preferably has a glass transition temperature (Tg) of 40 to 100 ° C. If the glass transition temperature is less than 40 ° C, the hardness and scratch resistance may be insufficient. When it exceeds 100 degreeC, there exists a possibility that the viscosity of the composition for hard-coat layers may rise, or the said composition may gelatinize. The lower limit of the glass transition temperature is more preferably 50 ° C, and the upper limit is more preferably 70 ° C.
The glass transition temperature is a value obtained by a method of calculating from the Tg of the monomer constituting the polymer.

The (meth) acrylic polymer preferably has an acid value of 1 mgKOH / g or less. When the acid value exceeds 1 mgKOH / g, there is a possibility that a hard coat layer having a desired hardness cannot be obtained. Moreover, blocking prevention property may be inferior.
The acid value is more preferably 0.8 mgKOH / g or less.

The (meth) acrylic polymer is preferably contained in the binder resin of the hard coat layer composition in a solid content of 5 to 20% by mass. If it is less than 5% by mass, the remaining marking mark may not be prevented. If it exceeds 20% by mass, the hardness of the hard coat layer may be lowered. The content of the (meth) acrylic polymer is more preferably 10 to 20% by mass.

It is preferable that the composition for hard-coat layers of this invention contains a photoinitiator.
The photopolymerization initiator is not particularly limited as long as it is a known one. For example, acetophenones (for example, trade name Irgacure 184, 1-hydroxy-cyclohexyl-phenyl-ketone manufactured by Ciba Specialty Chemicals, Inc. Name Irgacure 907, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one), benzophenones, thioxanthones, benzoin, benzoin methyl ether, manufactured by Ciba Specialty Chemicals, Aromatic diazonium salts, aromatic sulfonium salts, aromatic iodonium salts, metathelone compounds, benzoin sulfonic acid esters and the like can be mentioned. Of these, acetophenones are preferable.

It is preferable that content of the said photoinitiator is 1-7 mass parts with respect to 100 mass parts of resin solid content in the composition for hard-coat layers of this invention. If the amount is less than 1 part by mass, the amount of the photopolymerization initiator may be insufficient, resulting in insufficient curing. When the amount exceeds 7 parts by mass, the photopolymerization initiator becomes excessive, and a difference in the photopolymerization reaction due to the excess is caused.
The content of the photopolymerization initiator is more preferably 2 to 5 parts by mass with respect to 100 parts by mass of the resin solid content.

The composition for hard coat layers may further contain other components as necessary in addition to the components described above.
Examples of the other components include a thermal polymerization initiator, an ultraviolet absorber, a light stabilizer, a crosslinking agent, a curing agent, a polymerization accelerator, a viscosity modifier, an antistatic agent, an antioxidant, an antifouling agent, a slip agent, A refractive index adjusting agent, a dispersing agent, etc. can be mentioned. These can use a well-known thing.

The hard coat layer composition of the present invention can be prepared by mixing and dispersing the above-mentioned leveling agent, silica fine particles, binder resin, and, if necessary, a photopolymerization initiator, and other components in a solvent. it can.
The mixing and dispersing may be performed using a known apparatus such as a paint shaker, a bead mill, a kneader.

Examples of the solvent include water, alcohol (eg, methanol, ethanol, propanol, isopropanol, n-butanol, s-butanol, t-butanol, benzyl alcohol, PGME, ethylene glycol), ketone (eg, acetone, methyl ethyl ketone, methyl isobutyl). Ketone, cyclopentanone, cyclohexanone, heptanone, diisobutyl ketone, diethyl ketone), aliphatic hydrocarbon (eg, hexane, cyclohexane), halogenated hydrocarbon (eg, methylene chloride, chloroform, carbon tetrachloride), aromatic hydrocarbon (Eg, benzene, toluene, xylene), amide (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ether (eg, diethyl ether, dioxane, tetrahydrofuran), ether Ether alcohols (e.g., 1-methoxy-2-propanol), esters (e.g., methyl acetate, ethyl acetate, butyl acetate, isopropyl acetate) and the like.
Among them, as the solvent, methyl isobutyl ketone and / or methyl ethyl ketone can be suitably applied with the hard coat layer composition of the present invention by dissolving or dispersing the above-described resin component and other additives. Is preferred.

The hard coat layer composition of the present invention preferably has a total solid content of 30 to 45%. If it is less than 30%, residual solvent may remain or whitening may occur. When it exceeds 45%, the viscosity of the composition for a hard coat layer of the present invention is increased, the coating property is lowered, unevenness and streaks appear on the surface, and interference fringes may occur. The solid content is more preferably 35 to 45%.

The composition for hard coat layer of the present invention is applied on a light-transmitting substrate to be described later to form a coating film, dried as necessary, and then the coating film is cured to form a hard coat layer. Can be formed.

Examples of a method for forming a coating film by applying the composition for a hard coat layer of the present invention include, for example, a spin coating method, a dip method, a spray method, a die coating method, a bar coating method, a roll coater method, a meniscus coater method, a flexographic method. Various known methods such as a printing method, a screen printing method, and a bead coater method can be exemplified.

The coating amount (dry coating amount) is preferably ³ to 15 g / m ² . If it is less than 3 g / m ² , a hard coat layer having a desired hardness may not be obtained. If it exceeds 15 g / m ² , curling and damage may be insufficiently prevented. The coating amount is more preferably 4 to 9 g / m ² .

Although it does not specifically limit as said drying method, Generally it is good to dry for 3 to 120 second at 30-120 degreeC.

What is necessary is just to select a well-known method suitably as a method of hardening the said coating film according to the content etc. of the composition for hard-coat layers of this invention. For example, if the resin component contained in the composition for hard coat layers of the present invention is of an ultraviolet curable type, the coating film may be cured by irradiating with ultraviolet rays.
When irradiating the ultraviolet light is preferably ultraviolet irradiation amount is 80 mJ / cm ² or more, more preferably 100 mJ / cm ² or more, more preferably 130 mJ / cm ² or more.

The hard coat layer preferably has a layer thickness of 3 to 15 μm.
If it is less than 3 μm, the hardness may be insufficient. If it exceeds 15 μm, residual solvent may remain or coating film adhesion may be reduced. The layer thickness of the hard coat layer is more preferably 4 to 9 μm.
The layer thickness is a value obtained by measuring the cross section of the hard coat layer with an electron microscope (SEM, TEM, STEM).

The light transmissive substrate preferably has smoothness and heat resistance and is excellent in mechanical strength.
Specific examples of the material forming the light-transmitting substrate include polyester (polyethylene terephthalate, polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, and polypropylene. , Thermoplastic resins such as polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate or polyurethane, preferably polyester (polyethylene terephthalate, polyethylene naphthalate), triacetyl cellulose And polymethyl methacrylate.

As the light transmissive substrate, an amorphous olefin polymer (Cyclo-Olefin-Polymer: COP) film having an alicyclic structure can also be used. This is a base material in which norbornene polymer, monocyclic olefin polymer, cyclic conjugated diene polymer, vinyl alicyclic hydrocarbon polymer resin, etc. are used. ZEONEX and ZEONOR (norbornene resin) manufactured by Sumitomo Bakelite Co., Ltd., Sumilite FS-1700, JSR arton (modified norbornene resin), Mitsui Chemicals Appel (cyclic olefin copolymer), Ticona Topas ( Cyclic olefin copolymer), Hitachi Chemical's Optretz OZ-1000 series (alicyclic acrylic resin), and the like. Further, the FV series (low birefringence, low photoelastic modulus film) manufactured by Asahi Kasei Chemicals is also preferable as an alternative base material for triacetylcellulose.

It is preferable to use the thermoplastic resin as a flexible film-like body as the light-transmitting substrate. However, depending on the use mode in which curability is required, these thermoplastic resin plates are used. It is also possible, or a glass plate plate may be used.

The thickness of the light transmissive substrate is preferably 20 to 300 μm, more preferably an upper limit of 200 μm and a lower limit of 30 μm. When the light-transmitting substrate is a plate-like body, the thickness may exceed these thicknesses.
The light-transmitting substrate is called an anchor agent or primer in addition to physical treatment such as corona discharge treatment and oxidation treatment to improve adhesion when an antiglare layer is formed thereon. Application of the paint may be performed in advance.

The present invention also includes a hard coat film comprising the above-described light-transmitting substrate and a hard coat layer, and the hard coat layer is a cured product of the hard coat layer composition of the present invention.
The hardness of the hard coat film of the present invention is preferably 3H or more, and more preferably 4H or more, in a pencil hardness test (load 4.9 N) according to JIS K5600-5-4 (1999).

The hard coat film of the present invention preferably has a total light transmittance of 90% or more. If it is less than 90%, color reproducibility and visibility may be impaired when mounted on the display surface, and a desired contrast may not be obtained. The total light transmittance is more preferably 91% or more.
The total light transmittance can be measured by a method based on JIS K-7361 using a haze meter (manufactured by Murakami Color Research Laboratory, product number: HM-150).

The hard coat film of the present invention preferably has a haze of 1% or less. If it exceeds 1%, the desired optical properties cannot be obtained, and the visibility when the hard coat film of the present invention is placed on the image display surface is lowered.
The haze can be measured by a method based on JIS K-7136 using a haze meter (manufactured by Murakami Color Research Laboratory, product number: HM-150).

As described above, the hard coat film of the present invention has a hard coat layer formed by using the composition for a hard coat layer of the present invention containing a specific leveling agent and silica fine particles. Therefore, the hard coat film of the present invention has excellent leveling properties and antiblocking properties.
Moreover, the hard coat film of this invention can have high hardness and the outstanding restoring | restoration property by containing the urethane (meth) acrylate which has an isocyanur skeleton as binder resin.

Also, a polarizing plate comprising a polarizing element, the polarizing plate comprising the hard coat film of the present invention by bonding a light-transmitting substrate on the surface of the polarizing element, and the like. It is one of.

The polarizing element is not particularly limited, and for example, a polyvinyl alcohol film, a polyvinyl formal film, a polyvinyl acetal film, an ethylene-vinyl acetate copolymer saponified film, etc. dyed and stretched with iodine or the like can be used. In laminating the polarizing element and the hard coat film of the present invention, it is preferable to saponify the light-transmitting substrate. Adhesiveness is improved by the saponification treatment.

The present invention is also an image display device comprising the hard coat film or the polarizing plate on the outermost surface. Examples of the image display device include LCD, PDP, FED, ELD (organic EL, inorganic EL), CRT, touch panel, and electronic paper.

The LCD includes a transmissive display body and a light source device that irradiates the transmissive display body from the back. When the image display device of the present invention is an LCD, the antiglare film of the present invention or the polarizing plate of the present invention is formed on the surface of the transmissive display.

When the present invention is a liquid crystal display device having the hard coat film, the light source of the light source device is irradiated from the lower side (base material side) of the hard coat film. Note that in the STN liquid crystal display device, a retardation plate may be inserted between the liquid crystal display element and the polarizing plate. An adhesive layer may be provided between the layers of the liquid crystal display device as necessary.

The PDP includes a front glass substrate and a rear glass substrate disposed with a discharge gas sealed between the front glass substrate and the front glass substrate. When the image display device of the present invention is a PDP, the surface of the surface glass substrate or the front plate (glass substrate or film substrate) is provided with the hard coat film described above.

Other image display devices are ELD devices that emit light when zinc is applied, such as zinc sulfide or diamine substances, deposited on a glass substrate, and display the voltage by controlling the voltage applied to the substrate. It may be an image display device such as a CRT that generates an image visible to human eyes. In this case, the hard coat film described above is provided on the outermost surface of each display device as described above or the surface of the front plate.

In any case, the hard coat film of the present invention can be used for display display of a television or a computer. In particular, it can be suitably used for the surface of a high-definition image display such as a liquid crystal panel, PDP, ELD, touch panel, and electronic paper.

Since the composition for hard-coat layers of this invention consists of the structure mentioned above, the hard-coat film provided with the hard-coat layer which has the outstanding leveling performance and blocking performance can be obtained. Therefore, the hard coat film of the present invention using the hard coat layer composition of the present invention is a cathode ray tube display (CRT), a liquid crystal display (LCD), a plasma display (PDP), an electroluminescence display (ELD). It can be suitably used for displays such as electronic paper, particularly high definition displays.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples.
In the text, “part” or “%” is based on mass unless otherwise specified.

(Example 1)
4 parts by mass of Irgacure 184 (photopolymerization initiator, manufactured by BASF Japan Ltd.) was added to a mixed solvent of methyl ethyl ketone (MEK) / methyl isobutyl ketone (MIBK), and dissolved by stirring. The final solid content was 40% by mass. A solution of was prepared. To this solution, pentaerythritol triacrylate (PETA) and U-4HA (tetrafunctional urethane oligomer, weight average molecular weight 600, manufactured by Shin-Nakamura Chemical Co., Ltd.) and U-15HA (15 functional urethane oligomer, weight average molecular weight 2300) are used as resin components. , Manufactured by Shin-Nakamura Chemical Co., Ltd.) and polymer (7975-D41, acrylic double bond equivalent 250, weight average molecular weight 15000, manufactured by Hitachi Chemical Co., Ltd.) in terms of solid content, 25 parts by mass: 25 parts by mass: 40 parts by mass : It added and stirred so that it might become 10 mass parts. To this solution, 0.2 parts by mass of a leveling agent (product name: Megafac F-477, manufactured by DIC) was added and stirred, and further, silica fine particles (SIRMIBK15WT% -E65, manufactured by CIK Nanotech). ) Was added at a solid content ratio of 2 parts by mass and stirred to prepare a composition for a hard coat layer.
This hard coat layer composition is dried on a triacetyl cellulose (TAC) substrate (trade name KC4UAW, thickness 40 μm, manufactured by Konica Minolta Opto) so as to have a dry coating amount of 8 g / m ² by slit reverse coating. It was applied to form a coating film. After drying the obtained coating film at 70 ° C. for 1 minute, the coating film was cured by irradiating with ultraviolet rays at an ultraviolet irradiation amount of 150 mJ / cm ² to form a hard coat layer having a thickness of 7 μm. A coated film was obtained.
“Megafac F-477” is a fluorine leveling agent having a monomer composition of polypropylene glycol monoacrylate, polyethylene glycol monoacrylate, and 2- (perfluorohexyl) ethyl acrylate.

(Example 2)
In the hard coat layer composition of Example 1, a hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that the amount of the leveling agent was 0.1 part by mass. Got.

(Example 3)
In the hard coat layer composition of Example 1, a hard coat film was formed on the TAC substrate in the same manner as in Example 1 except that the amount of the leveling agent was 0.6 parts by mass. Got.

Example 4
In the composition for hard coat layer of Example 1, a hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that the amount of silica fine particles was 1 part by mass to obtain a hard coat film. It was.

(Example 5)
In the composition for hard coat layer of Example 1, a hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that the amount of silica fine particles was 1.5 parts by mass. Got.

(Example 6)
In the composition for hard coat layer of Example 1, a hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that the amount of silica fine particles was 3 parts by mass to obtain a hard coat film. It was.

(Example 7)
In the composition for hard coat layer of Example 1, the TAC group was the same as Example 1 except that the amount of the leveling agent was 0.6 parts by mass and the amount of the silica fine particles was 1.3 parts by mass. A hard coat layer was formed on the material to obtain a hard coat film.

(Example 8)
In the composition for hard coat layer of Example 1, 100 parts by mass of beam set DT3 (a mixture of acrylic monomer, acrylic acrylate oligomer and acrylic acrylate polymer, manufactured by Arakawa Chemical Industry Co., Ltd.) is used as a resin component, and the compounding amount of silica fine particles A hard coat film was obtained by forming a hard coat layer on the TAC substrate in the same manner as in Example 1 except that the content was 1.5 parts by mass.

(Comparative Example 1)
In the composition for the hard coat layer of Example 1, instead of the leveling agent (product name: Megafac F-477, manufactured by DIC Corporation), a leveling agent (Product name: Megafac F-444, manufactured by DIC Corporation) is used. A hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that a hard coat film was obtained.
“Megafac F-444” is a fluorine-based leveling agent composed of a compound represented by the following chemical formula (1).

(Comparative Example 2)
In the composition for the hard coat layer of Example 1, instead of the leveling agent (product name: Megafac F-477, manufactured by DIC), a leveling agent (Product name: Megafac F-554, manufactured by DIC) is used. A hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that a hard coat film was obtained.
“Megafac F-554” is a fluorine leveling agent having polyisobutylene glycol monoacrylate and 2- (perfluorohexyl) ethyl acrylate as monomer compositions.

(Comparative Example 3)
In the composition for the hard coat layer of Example 1, instead of the leveling agent (product name: Megafac F-477, manufactured by DIC), a leveling agent (Product name: Megafac F-552, manufactured by DIC) is used. A hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that a hard coat film was obtained.
“Megafac F-552” is a fluorine-based leveling agent having a monomer composition of methyl methacrylate, octadecyl acrylate, and 2- (perfluorohexyl) ethyl acrylate.

(Comparative Example 4)
In the composition for the hard coat layer of Example 1, instead of the leveling agent (product name: Megafac F-477, manufactured by DIC Corporation), a leveling agent (product name: Megafac MCF-350, manufactured by DIC Corporation) is used. A hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that a hard coat film was obtained.
“Megafac MCF-350” is a compound represented by methyl methacrylate, hydroxyethyl methacrylate (HEMA), tolylene diisocyanate (TDI), 2- (perfluorooctyl) ethyl acrylate and the following chemical formula (2). It is a fluorine leveling agent having a monomer composition.

(Reference column 1)
In the hard coat layer composition of Example 1, a hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that the amount of the leveling agent was 0.05 part by mass. Got.

(Reference Example 2)
In the composition for hard coat layer of Example 1, a hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that the amount of silica fine particles was 0.5 parts by mass. Got.

(Reference Example 3)
In the composition for the hard coat layer of Example 1, on the TAC base material in the same manner as in Example 1 except that the amount of the leveling agent was 0.7 parts by mass and the amount of the silica fine particles was 1 part by mass. A hard coat layer was formed on to obtain a hard coat film.

(Reference Example 4)
In the composition for hard coat layer of Example 1, a hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that the amount of silica fine particles was changed to 5 parts by mass to obtain a hard coat film. It was.

(Reference Example 5)
In the composition for hard coat layer of Example 1, the hard coat layer was formed on the TAC substrate in the same manner as in Example 1 except that only 100 parts by mass of pentaerythritol triacrylate (PETA) was used as the resin component. The hard coat film was obtained.

The obtained hard coat film was evaluated in the following items. The evaluation results are shown in Table 1.
<Pencil hardness test>
Each hard coat film was conditioned for 2 hours under the conditions of a temperature of 25 ° C. and a relative humidity of 60%, and then, using a test pencil (hardness HB to 3H) specified by JIS-S-6006, JISK5600-5-4. According to the pencil hardness evaluation method specified in (1999), the pencil hardness of the surface on which the hard coat layer was formed was measured under a load of 4.9 N.

<Blocking prevention>
Two hard coat films were prepared, and the hard coat layers were rubbed together to evaluate the slipperiness according to the following criteria.
◎: Good slippery ○: Slippery △: Slightly slippery ×: Nonslippery

<Leveling properties>
The hard coat film was visually evaluated by transmission and reflection under a fluorescent lamp.
○: No problem in appearance ×: Unsatisfactory appearance due to lack or excess of leveling agent such as unevenness, streaks, whitening, haze increase, poor compatibility, etc.

From Table 1, the hard of the Example using the composition for hard-coat layers containing the fluorine-type leveling agent which made the monomer composition the polypropylene glycol monoacrylate, polyethyleneglycol monoacrylate, and 2- (perfluorohexyl) ethylacrylate. The coated film had good results in all of the pencil hardness test, anti-blocking property and leveling property.
On the other hand, the hard coat of the comparative example using the composition for hard-coat layers containing the fluorine-type leveling agent which did not make polypropylene glycol monoacrylate, polyethyleneglycol monoacrylate, and 2- (perfluorohexyl) ethylacrylate as a monomer composition All the films were inferior in blocking prevention property.
In addition, both the hard coat film of Reference Example 1 using the hard coat layer composition having a low fluorine-based leveling agent content and the hard coat film of Reference Example 2 having a low content of silica fine particles were examples. Compared with the anti-blocking property. Moreover, since the hard coat film of Reference Example 3 having a high leveling agent content was whitened and foaming of the composition for the hard coat layer occurred, the leveling property was inferior in evaluation, and the content of silica fine particles in Reference Example 4 was high. The hard coat film had high haze and was inferior in leveling evaluation. Moreover, the hard coat film of Reference Example 5 using only PETA as the resin component was inferior in pencil hardness.

Hard coat films using the hard coat layer composition of the present invention include cathode ray tube display (CRT), liquid crystal display (LCD), plasma display (PDP), electroluminescence display (ELD), touch panel, electronic paper, etc. It can be suitably used for a display, particularly a high definition display.

Claims (7)

A hard coat layer composition containing a leveling agent, silica fine particles, and a binder resin,
The leveling agent contains a fluorine-based leveling agent having a monomer composition of polypropylene glycol monoacrylate, polyethylene glycol monoacrylate, and 2- (perfluorohexyl) ethyl acrylate,
The binder resin contains pentaerythritol tri (meth) acrylate in the binder resin component in a solid content of 15 to 35% by mass,
Content of the said silica fine particle is 1-4 mass parts with respect to 100 mass parts of binder resin solid content.
The composition for hard-coat layers characterized by the above-mentioned . Fluorine atom content in the fluorine-based leveling agent, a hard coat layer composition according to claim 1, wherein the 7-34% by weight. The composition for hard coat layers according to claim 1 or 2 , wherein the fluorine-based leveling agent has a weight average molecular weight of 11,000 to 25,000. The composition for hard-coat layers of any one of Claims 1-3 which contains 5-60 mass parts of fluorine-type leveling agents with respect to 100 mass parts of silica fine particles. Having a light transmissive substrate and a hard coat layer,
The said hard-coat layer consists of hardened | cured material of the composition for hard-coat layers of any one of Claims 1-4 , The hard-coat film characterized by the above-mentioned. A polarizing plate comprising a polarizing element,
A polarizing plate comprising the hard coat film according to claim 5 on the surface of the polarizing element. An image display device comprising the hard coat film according to claim 5 or the polarizing plate according to claim 6 on an outermost surface.