HK1142686B - Antireflection film - Google Patents

Description

Anti-reflection film

Technical Field

The present invention relates to an antireflection film capable of preventing or reducing reflection.

Background

In image display devices such as CRTs, PDPs, and LCDs, antireflection films are generally disposed on the outermost surface of a display in order to prevent contrast reduction and image mapping due to reflection of ambient light and to reduce the surface reflectance of the display using the principle of optical interference.

In recent years, there is an increasing tendency to use various displays outdoors. Therefore, there is a demand for further improvement in display quality and for clear recognition of a display image.

In order to satisfy these requirements, patent documents 1 and 2 listed below show that a coating layer containing transparent fine particles is formed on the surface of a transparent film substrate, and ambient light is diffusely reflected by the uneven surface.

In contrast, there is known an antireflection film in which a hard coat layer made of a metal oxide or the like and a low refractive index layer are laminated on the surface of a transparent film substrate, or a low refractive index layer made of an inorganic compound, an organic fluorine compound or the like is formed as a single layer. This antireflection film has an antireflection effect over a wide range of visible light and is used by being stuck to the surface of a display (see patent document 3 below).

The antireflection layer in which the hard coat layer made of the metal oxide or the like and the low refractive index layer are laminated or the low refractive index layer made of an inorganic compound or an organic fluorine compound is formed as a single layer is generally formed by a dry coating method such as a PVD (physical vapor deposition) method (vacuum deposition method, reactive deposition method, ion beam assisted method, sputtering method, ion plating method, or the like), a CVD (chemical vapor deposition) method, or the like. This dry coating method has disadvantages that the size of the substrate is limited, it is not suitable for continuous production, and the production cost is high.

Therefore, in order to achieve large area and continuous production, it is attracting attention to produce an antireflection film by a low-cost wet coating method (dip coating, spin coating, shower coating, spray coating, roll coating, gravure roll coating, air knife coating, doctor blade coating, wire-wound blade coating, knife coating, reverse coating, gate roll coating, micro-gravure coating, kiss coating, cast coating, slit nozzle coating, calender coating, die coating, etc.).

Methods for obtaining a low refractive index layer by a wet coating method are roughly classified into 1) a method of using a material containing a fluorine element having a low refractive index; 2) a method of providing a hole in the layer and reducing the refractive index by mixing air.

According to the above method, specific materials constituting the low refractive index layer include fluorine-containing organic materials, low refractive index fine particles, and the like, and these materials are used alone or in combination.

Patent document 1: japanese laid-open patent publication No. 7-290652

Patent document 2: japanese laid-open patent publication No. 7-294740

Patent document 3: japanese laid-open patent publication No. 6-230201

Disclosure of Invention

Technical problem to be solved by the invention

The antireflection layer formed by the methods of 1) and 2) has a problem of poor alkali resistance and peeling of the antireflection layer when wiped with an alkali detergent or the like.

In addition, the low refractive index layer used as the outermost layer of the antireflection film is required to have a low refractive index, and it is necessary that scratches are hardly caused by scratching or the like. Further, when a person uses the cosmetic composition, it is necessary that dirt such as fingerprints, sebum, sweat, and cosmetics is difficult to adhere to the cosmetic composition or that the cosmetic composition can be easily wiped off even if the dirt adheres to the cosmetic composition.

However, the low refractive index layer in the conventional art cannot satisfy all of the properties of refractive index, scratch resistance, and stain resistance. If these characteristics are not all satisfied, the antireflection film having a low refractive index layer cannot be used in practical applications.

The present invention has been made to solve the above problems of the prior art, and an object of the present invention is to provide an antireflection film in which a low refractive index layer is a low refractive index layer having a very low refractive index, and the surface of the low refractive index layer is hardly scratched by scratching or the like, the surface is not corroded by other chemicals such as an alkaline detergent, and the low refractive index layer is not peeled off; further, the present invention provides an antireflection film having a low refractive index layer, which is less likely to have stains such as fingerprints, sebum, sweat, and cosmetics adhered to the surface of the low refractive index layer, and which can be easily wiped off even if adhered thereto.

Means for solving the technical problem

In order to solve the above-described problems, the present invention provides an antireflection film in which a transparent substrate, a high refractive index layer having a higher refractive index than the transparent substrate, and a low refractive index layer having a lower refractive index than the high refractive index layer are laminated in this order, and the low refractive index layer is a cured product of a polymerizable composition containing hollow fine particles, a modified silicone, and a second resin component different from the modified silicone.

Effects of the invention

The present invention can provide an antireflection film having a low refractive index layer, a surface of which is hard to be scratched by scratching or the like, which is not corroded by chemicals, and which does not peel off, and further, in a preferred embodiment, an antireflection film which is hard to adhere dirt such as fingerprints, sebum, sweat, and cosmetics, and which can be easily wiped off even if adhered thereto.

Drawings

FIG. 1 is a sectional view of an antireflection film of the present invention.

Fig. 2 is a schematic cross-sectional view showing a state in which an antireflection film is attached to a display device. ,

fig. 3 is an explanatory view of a step of forming a modified silicone compound.

Description of the symbols

10

Transparent substrate

12

Low refractive index layer

Detailed Description

Reference numeral 10 in fig. 1 denotes an antireflection film of the present invention, and the antireflection film 10 is a laminate of a transparent substrate 11, a high refractive index layer (hard coat layer) 12 formed on the surface of the transparent substrate 11, and a low refractive index layer 15 formed on the surface of the high refractive index layer 12.

In the ambient light incident on the antireflection film 10, the phase difference between the reflected light reflected on the surface of the high refractive index layer 12 and the reflected light reflected on the surface of the low refractive index layer 15 and the reflected light reflected on the surface of the transparent substrate 11 is shifted, and the reflected lights cancel each other and attenuate.

Fig. 2 shows a state in which the antireflection film 10 of the present invention is attached to a surface of the display device 5 on which an image is displayed with a transparent adhesive or the like, which is not shown. As described above, since the reflected light of the ambient light is attenuated, the image of the display device 5 can be clearly observed.

The high refractive index layer 12 formed on the transparent substrate 11 is preferably formed using an ionizing radiation curable resin from the viewpoint of hardness or durability. The ionizing radiation curable resin is not particularly limited as long as it is used for the high refractive index layer, and can be appropriately selected from conventionally known ones.

More specifically, the ionizing radiation curable resin for the high refractive index layer contains a photopolymerizable oligomer, a photopolymerizable monomer, a photopolymerization initiator, and the like.

Examples of the photopolymerizable oligomer include polyester acrylate, epoxy acrylate, urethane acrylate, and polyol acrylate.

Examples of the photopolymerizable monomer include trimethylolpropane 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, isocyanuric acid EO-modified di (meth) acrylate, and dimethylol tricyclodecane di (meth) acrylate.

In the present invention, the (meth) acrylate refers to both acrylate and methacrylate.

When the high refractive index layer 12 is formed using an ionizing radiation curable resin containing such a photopolymerizable monomer and/or photopolymerizable oligomer, the refractive index of the high refractive index layer 12 can be made higher than the refractive index of the transparent substrate 11 described later. In particular, in the present invention, a (meth) acrylate or the like is preferably used as the photopolymerizable oligomer, and pentaerythritol tetra (meth) acrylate or the like is preferably used as the photopolymerizable monomer from the viewpoint of increasing the number of functional groups and improving the hardness or durability. These photopolymerizable prepolymers (photopolymerizable monomers and photopolymerizable oligomers) may be used in 1 kind, or 2 or more kinds may be used in combination.

The ionizing radiation-curable resin may contain, as a photopolymerization initiator, for example, any 1 or more selected from acetophenones, benzophenones, α -amyl oxime esters, tetramethylthiuram monosulfide, and thioxanthone.

Further, any 2 or more kinds selected from n-butylamine, triethylamine, and poly-n-butylphosphine may be used in combination as the photosensitizing agent.

When the high refractive index layer 12 is formed of a thermosetting resin, the composition of the polymerization initiator may be appropriately changed, and a peroxide is generally used.

The low refractive index layer 15 formed on the high refractive index layer 12 is a layer formed by curing a polymerizable composition containing a modified silicone compound as a first resin component, a second resin component different from the modified silicone compound, and hollow fine particles. The polymerizable composition is preferably an ionizing radiation curable resin composition.

The hollow fine particles are particles in which voids are formed in 1 fine particle, and for example, in hollow silica particles, the voids inside are covered with silicon oxide. Therefore, the refractive index of the hollow fine particles is lower than that of the normal non-hollow particles because the air filling the voids, and for example, the refractive index of the hollow silica particles is 1.45 or less than that of the normal silica particles, which is 1.46.

The specific gravity of the normal silica particles is about 2, and the specific gravity of the porous silica particles is about 1.7. The hollow silica particles are lighter than ordinary silica particles or porous silica particles, and have a specific gravity of 1.5 to 1.6.

The porous silica particles are formed by aggregating a plurality of silica fine particles, and gaps (voids) between the silica fine particles are exposed to the surface. Therefore, when the porous silica particles are added to the matrix, the matrix easily enters the inside of the voids. In contrast, even when the hollow silica particles are added to the matrix, the matrix does not enter the voids in the matrix, and the refractive index of the hollow silica particles does not increase.

Therefore, when hollow fine particles such as hollow silica particles are added to the ionizing radiation curable resin for the low refractive index layer 15, the refractive index of the low refractive index layer 15 can be lowered and the refractive index of the transparent substrate 11 can also be lowered, compared to the case where porous particles such as porous silica particles or normal particles are added.

Even when the high refractive index layer 12 does not contain or contains hollow fine particles such as hollow silica particles, the content (wt%) thereof is smaller than that of the low refractive index layer 15. Thereby, the refractive index of the low refractive index layer 15 can be made lower than the refractive index of the high refractive index layer 12.

That is, since the refractive index of the hollow silica particles is lower than that of the polymer of the (meth) acrylate, when the ionizing radiation-curable resin for the high refractive index layer 12 and the polymerizable composition for the low refractive index layer 15 are each composed mainly of the (meth) acrylate, the refractive index of the low refractive index layer 15 can be made lower than that of the high refractive index layer 12 by adding the hollow silica particles only to the polymerizable composition for the low refractive index layer 15.

The hollow fine particles include inorganic hollow fine particles such as silica and alumina, and organic hollow fine particles such as styrene and acrylic acid, and hollow silica particles are preferably used in the present invention from the viewpoint of easy availability.

The average particle diameter of the hollow fine particles is preferably 10nm to 200nm, more preferably 30nm to 60 nm.

When the average particle diameter is larger than 200nm, rayleigh scattered light is scattered on the surface of the low refractive index layer 15, and the layer looks whitish, and transparency thereof may be lowered. When the average particle diameter is less than 10nm, the hollow fine particles may aggregate.

Further, as the hollow fine particles, particles having a functional group which polymerizes by ionizing radiation on the surface are preferably used.

The functional group on the surface of the hollow fine particle is not particularly limited, and a functional group capable of polymerizing with a modified silicone compound or a second resin component described later is preferable, such as a (meth) acryloyl group or a vinyl group.

The hollow fine particles having such functional groups formed on the surface thereof have high affinity with a modified silicone compound or a second resin component described later, and therefore are uniformly mixed with the modified silicone compound or the second resin component in a coating liquid. Thus, the low refractive index layer 15 having a uniform film quality is obtained.

In the case of using hollow fine particles having a functional group formed on the surface thereof, when the modified silicone compound or the second resin component is polymerized by irradiation with ionizing radiation, the modified silicone compound or the second resin component reacts with the functional group on the surface of the hollow fine particle to bond to the surface of the hollow fine particle, and as a result, the mechanical strength of the low refractive index layer can be improved.

On the other hand, the modified silicone compound is preferably used as the first resin component of the polymerizable composition for the low refractive index layer 15 in order to improve the hardness, durability, and antifouling property of the low refractive index layer 15, and is preferably an ionizing radiation curable resin.

The modified silicone compound is represented by, for example, the following chemical formula (1).

..

The main skeleton has 2 or more siloxane structures (Si — O) bonded to each other, and in chemical formula (1), the main skeleton is polydimethylsiloxane having a methyl group bonded to Si of siloxane, the number and type of substituents bonded to Si of siloxane are not particularly limited, the number of substituents bonded to 1 Si is 0, 1, or 2, and the substituents include alkyl groups such as ethyl, propyl, butyl, and the like in addition to the methyl group.

The functional groups Ra, Rb are bonded to the silicon of the siloxane structure directly or via other bonds. When 2 or more functional groups Ra and Rb are present in 1 molecule of the modified silicone compound, the functional groups Ra and Rb may be the same type or different types.

The functional groups Ra and Rb are not particularly limited as long as they can react with each other or with another resin component (for example, the second resin component) preferably by ionizing radiation, more preferably by light irradiation. For example, functional groups Ra, Rb are methacryloyl, acryloyl, or mercapto.

In the case of explaining one example of the step of forming the modified silicone compound, for example, a silicone having 1 or more hydroxyl groups, an alkoxy compound having a functional group and an alkoxy group is used as a raw material (the upper half of reaction formula (1) in fig. 3). In the upper half part of the same reaction formula (1), the silicone is dimethylpolysiloxane (l ═ 10 to 14) having 2 hydroxyl groups.

The alkoxy compound has any 1 or more functional groups selected from a methacryloyl group, an acryloyl group, and a mercapto group as the functional group. In the upper half of the same reaction formula (1), the alkoxy compound is γ -methacryloxypropyltrimethoxysilane having 3 methoxy groups and methacryloyl groups.

When a mixture of the silicone and the alkoxy compound is heated, for example, by adding an additive (for example, hexanol) as needed, the hydroxyl group of the silicone and the alkoxy group of the alkoxy compound react, and the alkoxy compound is bonded to the silicone.

After the reaction is completed, the remaining additive, unreacted silicone, unreacted alkoxide, and by-product (methanol) are removed (for example, distillation under reduced pressure), and a modified silicone compound represented in the lower half of reaction formula (1) in fig. 3 is obtained.

The symbol R in FIG. 3 represents a functional group, which is the same as the functional group of the starting material alkoxide compound, and is a methacryloyl group here.

In fig. 3, symbol m represents the number of siloxane structures derived from the raw material silicone, and when the raw material silicone is polymerized in the step of reacting the silicone with the alkoxide compound, the number m of siloxane structures is greater than the number 1 of the raw material siloxane structures.

When 1630g/mol or more in functional group equivalent is used as the modified silicone compound, the anti-fouling property of the anti-reflective coating is improved as described later.

Functional group equivalent means the mass of the main backbone M (e.g., polydimethylsiloxane) bonded to each functional group. The labeling unit g/mol is 1mol in terms of the functional group.

The functional group equivalent of the modified silicone compound is obtained, for example, by using a nuclear magnetic resonance measuring apparatus (NMR)¹The spectral intensity of H-NMR (proton NMR) was determined.

¹In H-NMR, H (for example, Si- (CH) is determined for Si bonded to siloxane structure through C₃)₂H) spectral intensity of the functional group C-CH₃H, SH wherein H or C is H₂The spectral intensity ratio of H.

To obtain Si- (CH) of siloxane structure₃)₂The spectral intensity of H and the functional group C ═ CH₂The spectral intensity ratio of (A) to (B) is described as an example, and from the spectral intensity ratio, Si- (CH) of the siloxane structure contained in the sample is determined₃)₂Number of (a) and functional group C ═ CH₂The ratio of the number of (a) to (b).

Since the chemical formula of the siloxane structure and the chemical formula of the functional group are clarified in advance, the Si- (CH) of the siloxane structure₃)₂Number of (a) and functional group C ═ CH₂The ratio of the number of Si- (CH) contained in the measurement sample is found₃)₂The ratio of the number of siloxane structures A to the number of functional groups B of the bonds (A/B).

Since each has Si- (CH)₃)₂Since the molecular weight of the bonded siloxane structure (dimethylsiloxane here) is known, the value obtained by multiplying the molecular weight of each siloxane structure by the ratio (A/B) of the number A of the siloxane structures to the number B of the functional groups is Si- (CH) per functional group₃)₂The mass of the siloxane structure of the bond, i.e., the mass of the main skeleton, multiplied by the avogalois constant is the functional group equivalent (g/mol).

For example, attention is paid to polydimethylsiloxane (Si-CH)₃: chemical shift near 0ppm), methacryloyl group (C ═ CH)₂: chemical shifts in the vicinity of 4 to 7 ppm) and the like, and the presence ratio is calculated from the spectral intensity ratio obtained, and converted into a label unit (g/mol).

Examples of the modified silicone compound include those manufactured by shin-Etsu Silicone corporation under the product names "X-22-164" (functional group equivalent 190g/mol), "X-22-164 AS" (functional group equivalent 450g/mol), "X-22-164A" (functional group equivalent 860g/mol), "X-22-164B" (functional group equivalent 1630g/mol), "X-22-164C" (functional group equivalent 2370g/mol) and "X-22-164E" (functional group equivalent 3900 g/mol).

The content of the modified silicone compound in the polymerizable composition is preferably 10% by weight or less from the viewpoint of coating uniformity.

The second resin component of the polymerizable composition for the low refractive index layer 15 is a resin component different from the modified silicone compound, and is preferably an ionizing radiation curable resin component. Preferably, 90% by weight or more of the second resin component is a polyfunctional monomer.

Here, the polyfunctional monomer is preferably a monomer having 2 or more (meth) acryloyl groups. Examples of the polyfunctional monomer include esters of polyhydric alcohols and (meth) acrylic acid, specifically polyethylene glycol diacrylate, ethylene glycol di (meth) acrylate, 1, 4-dicyclohexyl diacrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 2, 3-cyclohexane tetramethacrylate, polyurethane polyacrylate, polyester polyacrylate, and the like.

These polyfunctional monomers may be used alone in 1 kind, or in a mixture of 2 or more kinds, in combination with the modified silicone compound of the first resin component for the low refractive index layer 15.

In particular, it is preferable to use either or both of di (meth) acrylate of a 2-functional monomer and tetra (meth) acrylate of a 4-functional monomer.

Oligomers such as polyester acrylate oligomers may also be used in an amount of less than 10% by weight of the second resin component.

The polymerizable composition for the low refractive index layer 15 may contain a photopolymerization initiator and a photosensitizer, which are the same as those used for the high refractive index layer 12, in addition to the hollow silica particles, the modified silicone compound, and the second resin component.

When the low refractive index layer 15 is formed of a thermosetting resin, the composition of the low refractive index layer can be appropriately changed by using a polymerization initiator, and a peroxide is generally used.

Examples of the transparent substrate 11 used in the present invention include films formed of transparent polymers such as polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetylcellulose and triacetylcellulose, and acrylic polymers such as polycarbonate polymers and polymethyl methacrylate.

The thickness of the transparent substrate 11 is not particularly limited, and may be generally 30 μm to 200 μm.

The method of applying the coating liquid for the high refractive index layer and the low refractive index layer of the present invention is not particularly limited, and examples thereof include a low-cost wet coating method (dip coating, spin coating, shower coating, spray coating, roll coating, gravure coating, air knife coating, wire-wound blade coating, reverse coating, gate roll coating, microgravure coating, kiss coating, cast coating, slit nozzle coating, calender coating, die coating, etc.).

After the coating layer is laminated by applying the coating liquid for the high refractive index layer and the coating liquid for the low refractive index layer in this order on the transparent substrate 11, the coating layer is cured by irradiation with ionizing radiation, and an antireflection film in which the high refractive index layer 12 and the low refractive index layer 15 are laminated on the transparent substrate 11 is obtained. Alternatively, the coating liquid for the high refractive index layer and the curing of the coating layer by the irradiation of ionizing radiation, and the coating liquid for the low refractive index layer and the curing of the coating layer by the irradiation of ionizing radiation are sequentially performed on the transparent substrate 11, whereby an antireflection film in which the high refractive index layer 12 and the low refractive index layer 15 are sequentially laminated on the transparent substrate 11 is obtained.

Examples of the ionizing radiation include, but are not limited to, ultraviolet rays and electron beams. In addition, when ionizing radiation is irradiated, the environment is also infinite, and irradiation may be performed in various environments such as air, inert gas such as nitrogen or argon, and particularly, a nitrogen atmosphere is preferable because the film quality of the high refractive index layer 12 and the low refractive index layer 15 becomes good.

Specifically, the transparent substrate on which the coating layer for the high refractive index layer or the low refractive index layer is formed is directly carried into a curing chamber, or the coating layer is dried to remove an excess solvent and then carried into the curing chamber.

While the internal space of the curing chamber is isolated from the atmospheric environment, the internal space of the curing chamber is evacuated while supplying nitrogen gas to the curing chamber to form a nitrogen gas atmosphere having an oxygen concentration of 1000ppm or less, and the coating layer is cured by irradiating ionizing radiation such as ultraviolet rays while maintaining the nitrogen gas atmosphere.

The thickness of the low refractive index layer 15 formed on the high refractive index layer 12 is not particularly limited, but is preferably 50nm to 200 nm. The surface roughness of the low refractive index layer 15 is also not particularly limited, and the average surface roughness thereof is preferably 1.0nm to 5 nm.

Examples

< example 1>

Dipentaerythritol hexaacrylate, EO-modified diacrylate, dimethylol tricyclodecane diacrylate, antimony pentoxide, and an initiator (1-hydroxy-cyclohexyl-phenyl ketone) were dissolved in isopropanol as a solvent to a solid content of 40% by weight, and a coating liquid for a high refractive index layer was prepared.

The solid component is a substance other than the solvent in the coating liquid, and here refers to a photopolymerizable prepolymer such as dipentaerythritol hexaacrylate, antimony pentoxide, and an initiator.

The coating liquid for a high refractive index layer was applied by the gravure method onto the surface of a triacetyl cellulose film (film thickness: 80 μm) of the transparent substrate 11 so that the dry film thickness became 2 μm, dried in an oven at 80 ℃ for 1 minute and 30 seconds, and then irradiated with a 160W high-pressure mercury lamp from a distance of 18cm for 3 seconds to be cured, thereby forming the high refractive index layer 12.

In order to form the low refractive index layer 15, the following coating liquid was prepared and formed.

The three materials were mixed in a compounding ratio of 8 wt% of a polyester acrylate oligomer, 35 wt% of pentaerythritol tetraacrylate and 57 wt% of polyethylene glycol diacrylate to prepare a matrix (second resin component).

A low refractive index coating agent (polymerizable composition) was prepared by adding 50.5 wt% of the matrix, 40 wt% of hollow silica particles having an average particle diameter of 60nm, 8 wt% of an alpha-hydroxyketone initiator, and 1.5 wt% of a modified silicone compound (functional group equivalent: 3900 g/mol).

The low refractive index coating agent was dissolved and dispersed in n-butanol as a solvent to prepare a coating liquid for a low refractive index layer containing 3.0 wt% of a solid component (low refractive index coating agent).

The coating liquid for the low refractive index layer was applied on the surface of the high refractive index layer 12 by the gravure method so that the dry film thickness became 10nm to form a coating layer, and after drying in an oven at 80 ℃ for 1 minute and 30 seconds, the coating layer was cured by irradiating light from a 160W high pressure mercury lamp from a distance of 18cm under a nitrogen atmosphere (oxygen concentration 1000ppm) for 3 seconds to form a low refractive index layer 15, whereby the antireflection film 10 of example 1 was obtained.

< example 2>

An antireflection film of example 2 was produced under the same conditions as in example 1, except that the content of the hollow silica particles in the low refractive index coating agent was changed from 40% by weight to 50% by weight, and the content of the matrix was changed from 50.5% by weight to 40.5% by weight.

< example 3>

An antireflection film of example 3 was produced under the same conditions as in example 1, except that the content of the hollow silica particles in the low refractive index coating agent was changed from 40% by weight to 60% by weight, and the content of the matrix was changed from 50.5% by weight to 30.5% by weight.

< example 4>

An antireflection film of example 4 was produced under the same conditions as in example 1, except that the content of the hollow silica particles in the low refractive index coating agent was changed from 40% by weight to 70% by weight, and the content of the matrix was changed from 50.5% by weight to 20.5% by weight.

< example 5>

An antireflection film of example 5 was produced under the same conditions as in example 2, except that the modified silicone compound was changed from 3900g/mol, which is the equivalent of the functional group, to 1630g/mol, which is the equivalent of the functional group.

< example 6>

An antireflection film of example 6 was produced under the same conditions as in example 1 above, except that the content of the hollow silica particles in the low refractive index coating agent was changed from 40% by weight to 30% by weight, and the content of the matrix was changed from 50.5% by weight to 60.5% by weight.

< example 7>

An antireflection film of example 7 was produced under the same conditions as in example 2, except that the modified silicone compound was changed from 3900g/mol, which is the equivalent of the functional group, to 190g/mol, which is the equivalent of the functional group.

< example 8>

An antireflection film of example 8 was produced under the same conditions as in example 2, except that the modified silicone compound was changed from 3900g/mol, which is the equivalent of the functional group, to 450g/mol, which is the equivalent of the functional group.

< example 9>

An antireflection film of example 9 was produced under the same conditions as in example 2, except that the modified silicone compound was changed from 3900g/mol, which is the functional group equivalent, to 860g/mol, which is the functional group equivalent.

< comparative example 1>

An antireflection film of comparative example 1 was produced under the same conditions as in example 2, except that the modified silicone compound was not added to the low refractive index coating agent.

< comparative example 2>

An antireflection film of comparative example 2 was produced under the same conditions as in example 1, except that the content of the hollow silica particles of the low refractive index coating agent was changed from 40% by weight to 80% by weight, the content of the modified silicone compound was changed from 1.5% by weight to 0, and the content of the matrix was changed from 50.5% by weight to 12% by weight.

The antireflection films of examples 1 to 9 and comparative examples 1 and 2 were used to perform the evaluation tests of "optical properties", "antifouling properties", "chemical resistance", "scratch resistance", "surface roughness", and "pencil hardness" shown below.

< optical characteristics (reflectance measurement) >

A black tape was attached to the back surface of the coating (the surface of the transparent substrate 11 opposite to the side on which the high refractive index layer 12 and the low refractive index layer 15 were laminated), and the resultant was measured by a spectrophotometer [ U-4100: hitachi ハイテクノロジ - ズ (Ltd.) the minimum reflectance (%) of the coated surface (the surface of the reflective film 10 on the side where the low refractive index layer 15 is formed) at an incident angle of 12 DEG for light having a wavelength of 370nm to 790nm was measured.

< antifouling Property (wiping property of oil-based Pen) >

The oily pen marks adhered to the coated surface were wiped off with a cellulose nonwoven fabric (ベンコツト M-3, manufactured by Asahi Kasei corporation) and the ease of wiping off was visually checked. The criteria for determination are as follows.

Very good: the liquid of the oil pen is flicked off and hardly adheres thereto, and can be completely wiped off.

O: the oily pen marks can be completely wiped off.

And (delta): wiping marks of the oily pen marks remained.

X: the oily pen marks could not be wiped off.

< chemical resistance (resistance to 1% NaOH Water solution) >

A black tape was attached to the back of the coating film, and a 1% NaOH aqueous solution was allowed to adhere to the coated surface, and after leaving to stand at room temperature for 30 minutes, the adhered 1% NaOH aqueous solution was wiped off, and a change in appearance was visually observed with a white fluorescent lamp. The criteria for determination are as follows.

Very good: the appearance was not changed at all.

O: the appearance is substantially unchanged.

And (delta): a portion whitened or a portion eroded.

X: whitening or complete erosion.

< scratch resistance (hardness) test >

The steel wire ball using #0000 was confirmed by visual observation at 250g/cm²The surface of the low refractive index layer 15 was repeatedly wiped 20 times under the load of (3). The criteria for determination are as follows.

Very good: no scratch was seen on the surface.

O: several scratches were visible on the surface.

And (delta): many scratches were visible on the surface.

X: scratches were visible throughout the surface.

< surface roughness >

The average surface roughness (Ra) was measured using an Atomic Force Microscope (AFM) [ product name "SPI 3800N", manufactured by セイコ - インスツルメンツ (ltd.) ].

< Pencil hardness test >

The test was carried out using a pencil hardness tester [ テスタ, manufactured by INDUSTRIAL CO., LTD.) under a load of 750g to confirm the presence or absence of scratches. The hardness of the pencil was 2H. The criteria for determination are as follows.

OK: each sample was subjected to 5 tests, and no scratch or dent was observed in 3 or more of the 5 tests.

NG: each sample was tested 5 times, and scratches, dents, etc. were observed 3 or more times among 5 times.

In the pencil hardness test, OK indicates that the pencil hardness is 2H or more.

The results of the above evaluation tests are shown in table 1 together with the equivalent of the functional group of the modified silicone compound and the content of the hollow silica particles.

TABLE 1

Evaluation of the results of the test

In table 1, "-" indicates that the content of the modified silicone acrylate compound was 0.

As is clear from table 1 above, in comparative examples 1 and 2 in which no modified silicone compound was added to the low refractive index layer, not only the antifouling property was poor, but also the pencil hardness was NG, and the lowest practically required properties as the antireflection film 10 were not satisfied.

In examples 1 to 9 in which the modified silicone compound was added to the low refractive index layer, not only the pencil hardness was 2H or more, but also the abrasion resistance test and the chemical resistance were excellent, and the practically required properties as an antireflection film were satisfied.

In examples 1 to 9, particularly, in examples 1 to 5 in which the equivalent weight of the functional group was 1630g/mol or more and the content of the hollow silica particles was 40 wt% or more and 70 wt% or less, good results were obtained in all the evaluation tests.

Example 6 has excellent properties such as stain resistance and pencil hardness, but has a reflectance as high as 1.79. Thus, when the content of the hollow silica particles exceeds 30% by weight, more preferably 40% by weight or more, the reflectance (refractive index) can be further reduced.

In examples 7 to 9, the optical properties, chemical resistance and the like were evaluated to be high, but the antifouling property was poor. As described above, in order to obtain high antifouling property in addition to excellent optical properties and chemical resistance, it is preferable that the low refractive index layer contains a modified silicone compound having a functional group equivalent of 1630g/mol or more.

Industrial applicability

The antireflection film is useful as an antireflection film to be disposed on the display surface of an image display device such as a CRT, PDP, or LCD.

Claims (10)

1. An antireflection film comprising a transparent substrate, a high refractive index layer having a higher refractive index than the transparent substrate, and a low refractive index layer having a lower refractive index than the high refractive index layer, which are laminated in this order, wherein the low refractive index layer is a cured product of a polymerizable composition containing hollow fine particles, a modified silicone compound, and a second resin component different from the modified silicone compound,

the polymerizable composition contains the modified silicone compound in an amount of 10 wt% or less, the hollow fine particles in an amount of 40 wt% to 70 wt%,

the second resin component contains 90 wt% or more of polyfunctional (meth) acrylate selected from the group consisting of esters of polyhydric alcohols and (meth) acrylic acid, urethane acrylate, and polyester acrylate,

the modified silicone compound has a main skeleton having 2 or more siloxane structures as repeating units and a functional group bonded to the main skeleton, wherein the value of the mass of the main skeleton divided by the number of moles of the functional group bonded to the main skeleton is 1630g/mol or more.

2. The antireflection film according to claim 1, wherein the hollow fine particles are hollow silica particles.

3. The antireflection film as claimed in claim 1 or 2, wherein the low refractive index layer is a cured product formed by irradiation with ionizing radiation.

4. The antireflection film as described in claim 1, wherein the functional group bonded to the main skeleton of the modified silicone compound is selected from a group of functional groups comprising an acryloyl group, a methacryloyl group and a mercapto group.

5. The antireflection film according to claim 1, wherein the average particle diameter of the hollow fine particles is 10nm or more and 200nm or less.

6. The antireflection film according to claim 1, wherein the hollow fine particles have a functional group which is polymerized by ionizing radiation on a surface thereof.

7. The antireflection film as claimed in claim 1, wherein the film thickness of the low refractive index layer is 50nm or more and 200nm or less.

8. The antireflection film according to claim 1, wherein the average surface roughness of the surface of the low refractive index layer is 1.0nm or more and 5nm or less.

9. The antireflection film as claimed in claim 1, wherein the low refractive index layer is a cured product of an ionizing radiation-curable polymerizable composition in a nitrogen atmosphere.

10. The antireflection film as described in claim 1, wherein the pencil hardness of the high refractive index layer is 2H or more.