WO2012133586A1 - Composition for forming low refractive index film, low refractive index film, plastic substrate, and display device - Google Patents

Abstract

A composition for forming a low refractive index film, the composition being characterized in containing a cross-linking compound having at least one methacryloyl group or acryloyl group in a monomer, a compound having a perfluro group and having no photoreactive functional group, and inorganic particles having a refractive index of 1.17-1.40.

Description

Low refractive index film forming composition, low refractive index film, plastic substrate, and display device

The present invention relates to a composition for forming a low refractive index film, a low refractive film, a plastic substrate provided with the film, and a display device.
This application claims priority on March 30, 2011 based on Japanese Patent Application No. 2011-076067 filed in Japan, the contents of which are incorporated herein by reference.

It is common that a transparent screen protection plate made of thin glass or plastic is used on the front surface of display devices such as portable terminals, digital cameras, and personal computers. Plastic screen protection plates are one of the most frequently used materials because they are lighter and cheaper than glass screen protection plates and are easy to handle. On the other hand, plastic is more easily damaged than glass. For this reason, a screen protection plate in which a hard coat for preventing scratches is formed on a hard plastic substrate such as an acrylic sheet having a relatively high hardness is often used.

However, in recent years, display devices such as mobile terminals are often touched with a finger directly on the screen of the display device, such as a touch panel method, so that fingerprints and the like often adhere to the screen. In the screen protection plate provided with a normal hard coat, when dirt such as fingerprints adheres to the protection board, there is a problem that these dirt cannot be removed by a simple method, and the remaining fingerprints become noticeable. In addition, these display devices that are often used outdoors often have a user's chance to view the screen under strong sunlight. For this reason, the surroundings and his / her face are reflected on the screen protection plate due to the reflection of sunlight, and the visibility of the display screen is lowered.

Dirty display screens and reduced visibility in display devices are serious problems that may necessitate improvements in technology for high-definition display devices in recent years. Therefore, there is a strong demand for a transparent plastic screen protection plate that has anti-fingerprint properties, has a low refractive index as it has anti-reflection performance, and has excellent film strength such as scratch resistance.

In order to solve the above problems, a composition for forming a low refractive index film comprising a perfluoro group-containing (meth) acrylic ester resin and hollow silica-based fine particles treated with a specific silane coupling agent Has been proposed (see Patent Document 1).

JP 2006-291077 A

However, the above-described conventional composition for forming a low refractive film has a problem that the film strength such as scratch resistance is weak although the anti-fingerprint property is obtained by the effect of the perfluoro group.

The present invention has been made in view of the above circumstances, and forms a low refractive index film having anti-fingerprint properties, anti-reflection properties that do not cause problems in use, and excellent film strength. One of the objects is to provide a composition that can be used.

The composition for forming a low refractive index film of the present invention includes a crosslinkable compound having one or more methacryloyl groups or acryloyl groups in a monomer, a compound having a perfluoro group and not having a photoreactive functional group, and It contains low refractive index inorganic particles having a refractive index of 1.17 or more and 1.40 or less.
In the composition for forming a low refractive index film of the present invention, the surface of the inorganic particles contained is preferably modified with an organic group containing at least one of an acryloyloxy group and a methacryloyloxy group.

According to the composition for forming a low refractive index film of the present invention, since the monomer has a crosslinkable compound having one or more methacryloyl groups or acryloyl groups, the mechanical strength of the film obtained when cured is increased, It is possible to prevent the film from being damaged. In addition, since it has a compound having a perfluoro group, it can repel dirt such as fingerprints to reduce the amount of adhesion, and further improve the wipeability of dirt such as attached fingerprints. And since this compound does not have a photoreactive functional group, it does not inhibit the polymerization of the crosslinkable compound and does not reduce the film strength. Moreover, since it has an inorganic particle whose refractive index is 1.17 or more and 1.40 or less, the refractive index of a coating film can be made low. That is, a film having fingerprint resistance, a low refractive index, and excellent film strength such as scratch resistance can be formed.

It is sectional drawing which shows an example of the plastic base material provided with the low refractive index film | membrane of one Embodiment of this invention. It is sectional drawing which shows another example of the plastic base material provided with the low refractive index film | membrane of one Embodiment of this invention. It is sectional drawing which shows another example of the plastic base material provided with the low refractive index film | membrane of one Embodiment of this invention. It is a perspective view which shows an example of a kind of smart phone of the display apparatus of one Embodiment of this invention.

The present invention relates to a composition for forming a low refractive index film, a low refractive index film, and a plastic substrate, and in particular, a reflection having fingerprint resistance suitable for use in a portable terminal, a digital camera, a personal computer or the like. The present invention relates to a prevention film, a plastic substrate including the film, and a display device.
Implementation of the composition for forming a low refractive index film of the present invention, a low refractive index film obtained from the composition, a plastic substrate provided with the film, and a display device having the low refractive index film or the plastic substrate The form for doing will be described below.
In addition, this form demonstrates the example of this invention concretely, in order to make the meaning of an invention understand better, and unless otherwise specified, this invention is not limited. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention.

[Composition for forming low refractive index film]
The composition for forming a low refractive index film of the present embodiment (hereinafter sometimes simply referred to as “composition”) is (a) a crosslinkable compound having one or more methacryloyl groups or acryloyl groups in the monomer, (B) a compound having a perfluoro group and not having a photoreactive functional group, and (c) low refractive index inorganic particles (inorganic particles).

"Crosslinkable compounds"
The crosslinkable compound of this embodiment will not be specifically limited if it is a crosslinkable compound which has a 1 or more methacryloyl group or acryloyl group in a monomer. Although it may have one or two, it preferably has 3 or more and 15 or less methacryloyl groups or acryloyl groups. More preferably, it has 4 or more and 10 or less, more preferably 5 or more and 8 or less, methacryloyl group or acryloyl group.
An increase in the number of these functional groups in the monomer is preferable because the reactivity is high and the crosslinking density is increased, and the film strength and weather resistance are improved.
The amount of the crosslinkable compound can be arbitrarily selected, but it is preferably 0.1 to 55% by mass and more preferably 0.5 to 10% by mass in the composition. Preferably, it is more preferably 0.8% by mass or more and 2% by mass or less.

The crosslinkable compound can be arbitrarily selected. Specific examples thereof include (meth) trimethylolpropane triacrylate, (meth) ditrimethylolpropane tetraacrylate, (meth) pentaerythritol triacrylate, (meth) pentaerythritol tetraacrylate, Examples include polyol polyacrylates such as (meth) dipentaerythritol hexaacrylate, epoxy (meth) acrylates, polyester (meth) acrylates, urethane acrylates, and polysiloxane acrylates. These may be used alone or in combination of two or more. Moreover, you may use suitably these oligomers and polymers as a crosslinkable compound of this invention. That is, the crosslinkable compound of the present invention is a monomer having one or more methacryloyl groups or acryloyl groups, and an oligomer or polymer having one or more methacryloyl groups or acryloyl groups obtained from these monomers.

A photopolymerization initiator may be used. When using, the kind and amount may be appropriately selected according to the crosslinkable compound used. For example, a known photopolymerization initiator such as benzophenone, diketone, acetophenone, benzoin, thioxanthone, quinone, benzyldimethyl ketal, alkylphenone, acylphosphine oxide, phenylphosphine oxide, etc. is used. be able to.

"Compounds with perfluoro groups and no photoreactive functional groups"
The compound having a perfluoro group and not having a photoreactive functional group is not particularly limited as long as the compound has one or more perfluoro groups and no photoreactive functional group. Examples thereof include fluorinated alkyl esters having a perfluoro group and a hydrophilic group in the side chain, and fluorinated aliphatic polymer esters having a perfluoro group and a lipophilic group in the side chain.

The compound having a perfluoro group and not having a photoreactive functional group is preferably contained in the composition in an amount of 0.1% by mass to 5.0% by mass. More preferably, the content is 0.1% by mass or more and 2% by mass or less, and more preferably 0.1% by mass or more and 1% by mass or less. When the amount is less than 0.1% by mass, sufficient anti-fingerprint characteristics may not be obtained. When the amount exceeds 5.0% by mass, sufficient film strength cannot be obtained, which is not preferable.

Perfluoro groups generally known as perfluoro groups can be used in the present application. Examples thereof include a perfluoroalkyl group, a perfluoroalkylene group, and a perfluoroalkylidene group. The number of carbon atoms contained in the perfluoroalkyl group and the like can be arbitrarily selected, and examples thereof include 1 to 20 carbon atoms.

Examples of the photoreactive functional group include a functional group whose reaction proceeds by irradiation with light energy such as ultraviolet rays. Examples of such a reaction include a photo radical polymerization reaction by a functional group having an ethylenically unsaturated bond. Specific examples of the photoreactive functional group include methacryloyl group, acryloyl group, vinyl group, allyl group, and styryl group.

When another layer or film is provided on the film formed by the composition of the present embodiment (for example, when printing characters or images), the contact angle with respect to hexadecane when the film of the present invention is formed is The amount of the compound having a perfluoro group and not having a photoreactive functional group may be appropriately adjusted so that the lipophilicity is 40 ° or less, preferably 35 ° or less.

"Inorganic particles"
The inorganic particles used in the present embodiment, that is, the inorganic particles having a low refractive index are not particularly limited as long as the refractive index is 1.17 or more and 1.40 or less. Examples of such inorganic particles include silica, and mesoporous silica having many voids is preferable in that a lower refractive index can be obtained. The type of mesoporous silica can be arbitrarily selected, and examples thereof include silica having uniform and regular pores having a diameter of about 2 to 10 nm.
A method for producing mesoporous silica is described in, for example, Japanese Patent Application Laid-Open Nos. 2001-233611 and 2002-79616.

The refractive index of the low refractive index inorganic particles is 1.17 or more and 1.40 or less, preferably 1.17 or more and 1.35 or less, more preferably 1.17 or more and 1.30 or less. Inorganic particles having a refractive index of less than 1.17 are difficult to produce. For example, even if they can be produced by greatly increasing the porosity, the strength of the particles themselves is weakened, and the scratch resistance of the formed low refractive index film, etc. Is not preferable because it may become weak. On the other hand, if the refractive index exceeds 1.40, the refractive index of the film may be too high when the film is formed, which is not preferable because the antireflection performance deteriorates.

In addition, the refractive index of the inorganic particle in this specification means the refractive index as the whole particle. For example, in the case of particles having voids in the particles, such as mesoporous silica, it means not only the refractive index of silica in the portion where mesoporous silica is formed but also the refractive index in which the void portion of mesoporous silica is also integrated.

When mesoporous silica is used as the low refractive index inorganic particles, the porosity represented by the volume occupied by the voids of the particles relative to the total volume of the particles is preferably 10% or more and 60% or less, and 20% or more and 60% or less. Is more preferable, and 30% or more and 60% or less are more preferable. By setting the porosity to the above range, the refractive index can be lowered while ensuring the strength of the particles. In order to make the mesoporous silica have a lower refractive index, if the porosity is increased, the particle shape becomes sparse and the strength of the particle becomes weak. From the viewpoint of scratch resistance, the low refractive index is less than 1.17. It is not preferable to use particles.

The average primary particle diameter of the inorganic particles having a low refractive index used in the present embodiment is preferably 3 nm or more and 100 nm or less. That is, it is preferable to use inorganic fine particles having an average primary particle diameter of 3 nm or more and 100 nm or less. Particles of less than 3 nm are not preferred because they may be difficult to produce and may not be easy to handle. On the other hand, particles larger than 100 nm are not preferable because, when formed into a film, loss of transmitted light due to Rayleigh scattering increases, which may reduce the transparency of the film.

The inorganic particles having a low refractive index are contained in the composition in an amount of 10% by mass to 90% by mass, preferably 20% by mass to 80% by mass, more preferably 40% by mass to 60% by mass. Is preferred. If it is less than 10% by mass, the refractive index may not be sufficiently low, such being undesirable. On the other hand, if it exceeds 90% by mass, the ratio of the crosslinkable compound in the whole composition is decreased, so that it may be difficult to obtain sufficient film strength.

The inorganic particles having low refraction may be modified with a surface treatment agent having an organic group on the surface of the particles in order to improve the affinity with the crosslinkable compound. As such a surface treatment agent, an organosilicon compound can be used, and examples thereof include a silicon-based coupling agent and silicone oil.

Examples of the silicon coupling agent include methyltrimethoxysilane, methyltriethoxysilane, phenyltriethoxysilane, methylmethoxysilane, n-propyltrimethoxysilane, n-butyltriethoxysilane, n-hexyltrimethoxysilane, Silane coupling agents such as n-hexyltriethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane and diphenyldimethoxysilane, vinylsilane couplings such as vinyltrimethoxysilane and vinyltriethoxysilane Agents, aminosilane coupling agents such as 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane Acryloyloxysilane coupling agents such as methacryloyl, methacryloyloxysilane coupling agents such as 3-methacryloxypropyltrimethoxysilane, mercaptosilane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc. Is mentioned.

Examples of the silicone oil include dimethyl silicone oil, methyl hydrogen silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, polyether-modified silicone oil, and amino-modified silicone oil.
These silicone coupling agents and silicone oils may be used alone or in combination of two or more.

Among these, acryloyloxysilane coupling agents such as 3-acryloxypropyltrimethoxysilane, methacryloyloxysilane coupling agents such as 3-methacryloxypropyltrimethoxysilane, and mercaptosilane cups such as 3-mercaptopropyltrimethoxysilane By using one or more selected from the group of ring agents as a surface treatment agent for inorganic particles having a low refractive index, the affinity with the resin is significantly improved, and the adhesion between the particles and the resin is improved. By improving, a high film strength can be obtained. More preferably, at least one of an acryloyloxysilane coupling agent and a methacryloyloxysilane coupling agent is used.

The viscosity of the composition is preferably 0.2 mPa · s or more and 500 mPa · s or less, and more preferably 0.5 mPa · s or more and 200 mPa · s or less. When the viscosity of the composition is less than 0.2 mPa · s, it is not preferable because the film thickness when formed into a film becomes too thin and it is difficult to control the film thickness. On the other hand, when the viscosity exceeds 500 mPa · s, the viscosity is too high and it becomes difficult to handle the composition at the time of coating.

In order to adjust to the above viscosity range, an organic solvent may be used as a diluent. The solvent is not particularly limited as long as it has good compatibility with the components of the composition. For example, aromatic solvents such as toluene and xylene, aliphatic solvents such as hexane and heptane, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ether solvents, ester solvents, amide solvents, cellosolve solvents, ethers Examples include ester solvents and alcohol solvents. These solvents may be used alone or in combination of two or more. Among these, alcohols are preferred because they do not dissolve the surface of the plastic substrate and do not erode the surface, and therefore do not reduce the transparency of the plastic substrate. Although the amount of the organic solvent is arbitrarily selected, for example, it is preferably 10% by mass or more and 99% by mass or less, and more preferably 50% by mass or more and 99% by mass or less in the composition.

In the composition of this embodiment, an antifoaming agent, a leveling agent, a water repellent, an oil repellent, a lipophilic agent, a lubricant, an antioxidant, an ultraviolet absorber, a light stabilizer, a polymerization inhibitor and the like are generally used. Additives may be added as appropriate.

"Method for producing composition for forming low refractive index film"
The method for producing the composition for forming a low refractive index film of the present embodiment is to uniformly distribute the crosslinkable compound, the compound having a perfluoro group and not having a photoreactive functional group, low refractive index inorganic particles, and the like. If it can be made to mix, it will not specifically limit, A well-known stirring method can be used.
In addition, when the surface modifier is modified on the surface of the low refractive index inorganic particles, the surface-modified inorganic particles may be mixed with the composition after surface modification in advance.

"Low refractive index film"
The low refractive index film of the present embodiment is formed by the low refractive index film forming composition of the present embodiment.
In this embodiment, the low refractive index of the film means that the refractive index is 1.49 or less. In the present embodiment, the refractive index of the low refractive index film is preferably from 1.26 to 1.49, more preferably from 1.28 to 1.47. By setting the refractive index of the film in the above range, the low refractive index film has a function as an antireflection film, and the visibility of the display screen can be improved.
Note that having a function as an antireflection film means that the visible light reflectance (the value obtained by multiplying the 10 ° specular reflectance of the film with a spectrophotometer multiplied by the relative visibility value) is 3.0 or less. It means that there is. The visible light reflectance is preferably 2.2 or less, and more preferably 1.5 or less. The lower limit of the visible light reflectance is 0, but is preferably 0.05 or more.

In addition, the low refractive index film of this embodiment is a water repellent film having a contact angle with water of 85 ° to 100 °. Since it is water repellent, it is possible to prevent adhesion of dirt such as fingerprints.
Further, when another layer or film is laminated on the low refractive index film of this embodiment, it is preferably a water-repellent and lipophilic film having a contact angle with respect to hexadecane of less than 40 °. Since it is lipophilic, another layer or film can be laminated on the low refractive index film of this embodiment by screen printing or the like.

Although the film thickness of the low refractive index film of the present embodiment can be arbitrarily selected, it is generally 10 nm or more and 1 mm or less, and preferably 50 nm or more and 200 nm or less. By setting the film thickness within the above range, reflected light in the visible light wavelength region can be reduced. For example, when used in a display device, the visibility of the display screen can be improved, which is preferable.

The surface resistance of the low refractive index film can be arbitrarily selected, but 1 × 10 ⁸ Ω / □ or more and 1 × 10 ¹³ Ω / □ or less can be given as an example, and 1 × 10 ⁹ Ω / □ or more. One preferred example is 1 × 10 ¹² Ω / □ or less.

The method for producing a low refractive index film of the present embodiment includes a step of forming a coating film by coating the low refractive index film forming composition on a substrate that is arbitrarily selected, and curing the coating film. And a step of causing.
Examples of the coating method in the step of forming a coating film include a spin coating method, a dip coating method, a gravure coating method, a spray method, a roller method, and a brush coating method.

Although the curing method in the step of curing the coating film can be arbitrarily selected, a method of photocuring by irradiating the coating film with energy rays is preferable. The energy rays used for photocuring are not particularly limited as long as the coating is cured, and for example, energy rays such as ultraviolet rays, far infrared rays, near ultraviolet rays, infrared rays, X rays, γ rays, electron beams, proton rays, neutron rays are used. be able to. Among these energy rays, curing by ultraviolet irradiation, which has a high curing rate and is easily available, is preferable.
By photocuring the coating film, the crosslinkable compound is polymerized and a film having excellent strength such as scratch resistance can be obtained.

In the case of UV curing, a method of irradiating at an energy of 100 to 3,000 mJ / cm ² using a high pressure mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp or the like that emits light in a wavelength band of 200 nm to 500 nm Etc.

As described above in detail, according to the composition for forming a low refractive film of the present embodiment, a crosslinkable compound having one or more methacryloyl groups or acryloyl groups in the monomer is different from the crosslinkable compound. And a compound having a perfluoro group as a component and not having a photoreactive functional group, the polymerization reaction of the crosslinkable compound is inhibited by the perfluoro group in the process of forming a film. Can be suppressed. Accordingly, the degree of polymerization of the crosslinkable compound can be increased, the mechanical strength of the film formed using the composition can be increased, and a film that is hardly damaged can be formed.

In addition, by including a compound having a perfluoro group, the amount of adhesion can be reduced by removing dirt such as fingerprints on the surface of the formed film, and the wiping property of dirt such as attached fingerprints can be improved. Can do.
In addition, a film having a low refractive index can be formed by including inorganic particles having a refractive index of 1.17 or more and 1.40 or less.

From the above, according to the composition of the present embodiment, it is possible to form a film having anti-fingerprint properties, excellent antireflection properties due to low refractive index, and excellent film strength such as scratch resistance.
In the present embodiment, whether or not it has fingerprint resistance may be determined in a general sense, but can be evaluated by the following method, for example. That is, one drop of trioleic acid is dropped on the film, and the haze of the film is measured before dropping trioleic acid and after wiping 10 times with a clean wiper, and the difference in haze values is less than 1.0 Can be determined to have fingerprint resistance.

When the effect in this embodiment is described, when the low refractive inorganic particles are surface-modified with at least one selected from an acryloyloxysilane coupling agent, a methacryloyloxysilane coupling agent, and a mercaptosilane coupling agent. By combining the crosslinkable compound and the surface modifier, a film having high film strength can be obtained.

When fine particles having an average primary particle size of 3 nm or more and 100 nm or less of the low refractive index inorganic particles are used, a low refractive index film excellent in transparency can be obtained.
In addition, when mesoporous silica is used as the low refractive index inorganic fine particles, the particles have voids and the refractive index of the particles becomes low, so that a film having a lower refractive index can be obtained.

According to the low refractive index film of the present embodiment, since it is a film formed by the composition for forming a low refractive index film of the present embodiment, it has anti-fingerprint properties and excellent antireflection performance due to its low refractive index, A film excellent in film strength can be obtained.

[Plastic substrate with low refractive index film]
The plastic substrate provided with the low refractive index film of the present embodiment is characterized by having the low refractive index film of the present embodiment on at least one surface of the plastic substrate.

The plastic substrate provided with the low refractive index film of the present embodiment will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing an example of a plastic substrate provided with the low refractive index film of the present embodiment. The plastic substrate 10 provided with this low refractive index film has a low refractive index film 12 on at least one surface of the plastic substrate 11.

FIG. 2 is a cross-sectional view showing another example of the plastic substrate provided with the low refractive index film of the present embodiment. The plastic substrate 20 provided with the low refractive index film is one of the plastic substrates 11. A hard coat film 13 is provided on the surface, and a low refractive index film 12 is provided on the surface of the hard coat film 13.

FIG. 3 is a cross-sectional view showing still another example of the plastic base material provided with the low refractive index film of the present embodiment. The plastic base material 30 provided with the low refractive index film is one of the plastic base materials 11. A hard coat film 13 on the surface, a high refractive index film 14 on the surface of the hard coat film 13, and a low refractive index film 12 on the surface of the high refractive index film 14. ing.

"Plastic substrate"
The plastic substrate 11 used in the present embodiment is not particularly limited as long as it is a plastic substrate. Examples of protective plates used for display screen protection include acrylic sheets, acrylic sheets containing highly elastic acrylic rubber, acrylic-styrene copolymer sheets, polystyrene sheets, polyethylene, polypropylene, polycarbonate, PET films, and A TAC film etc. can be mentioned. Moreover, as a plastic base material, you may use what laminated | stacked the 1 type (s) or 2 or more types of said base materials.

"Low refractive index film"
Since the low refractive index film 12 may be the same as that described in the item “Low refractive index film”, the description thereof is omitted.

"Hard coat film"
The configuration of the hard coat film 13 is not particularly limited as long as it has a hard coat property that can protect the plastic substrate from scratches and the like. That is, when steel wool (# 0000) is reciprocated 10 times (1 reciprocation: 200 mm) under a load of 250 g / cm ² on the hard coat film, there are 0 to 10 scratches visually. Any coating film may be used. From the viewpoints of reactivity, transparency, weather resistance, and hardness, those formed using a crosslinkable compound having at least one methacryloyl group or acryloyl group in the monomer are preferred. Further, the crosslinkable compound preferably has three or more methacryloyl groups or acryloyl groups. An increase in the number of these functional groups in the monomer is preferable because the reactivity is high and the crosslinking density is increased, and the film strength and weather resistance are improved.
Specific examples of the crosslinkable compound include (meth) trimethylolpropane triacrylate, (meth) ditrimethylolpropane tetraacrylate, (meth) pentaerythritol triacrylate, (meth) pentaerythritol tetraacrylate, (meth) dipentaerythritol hexa One or more kinds of polyol polyacrylates such as acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, urethane acrylate, polysiloxane acrylate and the like can be used. Moreover, you may use these oligomers and polymers suitably.

Further, the hard coat film 13 may have conductive fine particles in order to impart antistatic performance. The conductive fine particle is not particularly limited as long as it is a fine particle that can impart conductivity to the film. For example, metal fine particles such as gold, platinum, ruthenium, and iron, tin, antimony, indium, zinc, gallium, and aluminum And metal oxide fine particles containing one or more elements selected from the group.
Among these metal oxide fine particles, metal oxide fine particles having a semiconductor property with a band gap of 3.0 eV or more are preferable because they have both the property of transmitting visible light and electrical conductivity.

Examples of the metal oxide fine particles having such semiconductor properties include metal oxide fine particles containing one or more elements selected from the group consisting of tin, antimony, indium, and zinc. As the metal oxide fine particles, for example, antimony-containing tin oxide (ATO) fine particles, tin oxide (SnO ₂ ) fine particles, tin-containing indium oxide (ITO) fine particles, or the like can be used.
Further, the hard coat film 13 containing these metal oxide fine particles has a high refractive index of these metal oxide particles, so that the refractive index of the hard coat film 13 is increased. Therefore, the antireflective performance can be further improved by forming the low refractive index film 12 on the surface of the hard coat film 13.

The average primary particle diameter of the conductive fine particles is preferably 3 nm or more and 50 nm or less, more preferably 3 nm or more and 20 nm or less. By setting the average primary particle diameter of the conductive fine particles within the above range, good transparency and conductivity can be obtained.

The film thickness of the hard coat film 13 is preferably 0.1 μm or more and 20 μm or less, and more preferably 0.5 μm or more and 10 μm or less. By setting the film thickness of the hard coat film 13 in the above range, a film having high film strength and good transparency can be obtained.

The hard coat film 13 is a composition obtained by appropriately mixing the crosslinkable compound, the photopolymerization initiator, the conductive fine particles, and a solvent by a known method such as a dip coating method, like the low refractive index film 12. It is obtained by coating and then photocuring.

"High refractive index film"
The high refractive index film 14 is a film having a higher refractive index than that of the low refractive index film 12, and the antireflection function can be further improved by providing it between the hard coat film 13 and the low refractive index film 12. Such a high refractive index film 14 is obtained by a film containing titanium oxide, zirconium oxide or the like having an average primary particle diameter of 3 nm or more and 50 nm or less. In this embodiment, the film having a high refractive index means a film having a refractive index of 1.5 or more, for example. The refractive index of the high refractive index film 14 is preferably 1.55 or more, more preferably 1.65 or more. The upper limit of the refractive index is 2.2 or less, preferably 1.7 or less.

Further, an intermediate refractive index film having a refractive index lower than that of the high refractive index film 14 and higher than that of the low refractive index film 12 may be provided between the high refractive index film 14 and the low refractive index film 12.
Further, a conductive film may be provided between the hard coat film 13 and the low refractive index film 12.

As with the low refractive index film 12, the high refractive index film 14, the conductive film, and the like are prepared by mixing an inorganic fine particle having these properties with the above-mentioned crosslinkable compound, photopolymerization initiator, solvent, etc., as in the case of the low refractive index film 12. It can be obtained by coating by a known method such as photo-curing.

According to the plastic substrate provided with the low refractive index film of the present embodiment, since the low refractive index film of the present embodiment is provided, the anti-fingerprint property, the antireflection property and the film strength are excellent. Furthermore, when it has a hard coat film | membrane, the plastic base material which was excellent in film | membrane intensity | strength is obtained.

"Display device"
The display device according to the present embodiment is a display device including a plastic substrate including the low refractive index film according to the present embodiment or the low refractive index film according to the present embodiment.
The display device is not particularly limited, and examples thereof include a display device on which a touch panel display, a liquid crystal display, a light emitting diode display, an electroluminescence display, a fluorescent display, a plasma display panel, and the like are mounted. Examples of such display devices include ATMs such as mobile terminals, smartphones, digital cameras, personal computers, and financial institutions, automatic ticket vending machines, vending machines, car navigation devices, portable game machines, and copy machines.

Here, the display device of this embodiment will be described by taking a smartphone as an example of the display device. FIG. 4 is a perspective view illustrating an example of a kind of smartphone of the display device according to the present embodiment. In the smartphone 100, a display unit 102 including a touch panel display provided with a low refractive index film according to the present embodiment as a display surface is disposed on the front surface of a housing 101.

The method for forming the low refractive film of the present embodiment on the display surface of the display device is the same as the method for forming the low refractive index film described above, and it may be appropriately applied to each display (display surface). . Moreover, you may apply | coat so that it may have the hard coat film | membrane, high refractive index film | membrane, etc. which were demonstrated above between the low refractive index film | membrane and a display as needed. That is, a display may be used instead of the plastic substrate.
Further, the method for providing the plastic substrate provided with the low refractive index film of the present embodiment on the display surface of the display device is not particularly limited, and may be mounted on the display device by a known method.

According to the display device of this embodiment, since the plastic substrate provided with at least one of the low refractive index film and the antireflection film of this embodiment is provided, it has fingerprint resistance and visibility (antireflection property). ), A display device having excellent film strength can be obtained.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, the symbol in description of a back | latter stage shows the following content.

In the above table, “Seika Beam”, “Defenser”, “KAYARAD”, and “Mega Fuck” are registered trademarks.

[Refractive index]
The refractive index of the obtained composition was measured using a prism coupler (manufactured by Metricon) with the composition as a cured product.
In the method of converting the composition into a cured product, first, the obtained composition was applied to a PET film with a wire bar so that the dry film thickness was 1 μm. Subsequently, it dried at 60 degreeC for 5 minute (s), and it exposed so that it might become 300 mJ / cm < ² > of ultraviolet rays with a high pressure mercury lamp (120 W / cm), and hardened | cured material was obtained.

"Dispersion of low refractive index inorganic fine particles"
[Production Example 1]
20 g of mesoporous silica fine particles (SI-01 made by Sumitomo Osaka Cement Co., Ltd., primary particle size 5 to 15 nm, fine particle refractive index 1.26) and 80 g of isopropanol were mixed. Next, 150 g of this mixed solution and glass beads (φ = 0.1 mm) were put into a bead mill and subjected to a dispersion treatment at 3000 rpm for 5 hours. Next, the glass beads were separated by filtering to obtain a mesoporous silica fine particle dispersion.

"solvent"
[Production Example 2]
A solvent in which methanol, 1-butanol and butyl cellosolve were mixed at a mass ratio of 1: 1: 1 was obtained.

[Production Example 3]
A solvent in which 1-butanol, butyl cellosolve and propylene glycol monomethyl ether were mixed at a mass ratio of 1: 1: 1 was obtained.

"Composition for forming hard coat film"
[Production Example 4]
In addition to the solvent of Production Example 2 so that the DPHA was 30% by mass, 3% by mass of Irgacure 184 was added to and mixed with the mass of DPHA to obtain a composition for forming a hard coat film. When the refractive index of the hardened | cured material of this composition for hard-coat film formation was measured with the prism coupler (made by Metricon), it was 1.50.

"Composition for forming conductive hard coat film"
[Production Example 5]
DPHA is added to the solvent of Production Example 2 so that 28.5% by mass and ATO dispersion is 1.5% by mass in terms of ATO (refractive index 2.0), and Irgacure 184 is added to the total mass of DPHA and ATO. 3% by mass was added and mixed to obtain a composition for forming a hard coat film. When the refractive index of the hardened | cured material of this composition for hard-coat film formation was measured with the prism coupler (made by Metricon), it was 1.53.

"Composition for forming high refractive index film"
[Production Example 6]
Add DPHA to 1.5% by mass and the zirconia dispersion (Sumitomo Osaka Cement Co., Ltd. MZ-230X, zirconia refractive index: 2.2) to 3.5% by mass in terms of zirconia to the solvent of Production Example 2. Irgacure 127 was added in an amount of 3% by mass with respect to the total mass of DPHA and zirconia and mixed to obtain a composition for forming a high refractive index film. The refractive index of the cured product of this high refractive index film-forming composition was 1.65 as measured by a prism coupler (manufactured by Metricon).

[Example 1]
"Surface modification of low refractive index inorganic fine particles"
100 g of the mesoporous silica dispersion of Production Example 1, 3 g of KBM-5103 having an acryloyloxy group as a surface treating agent, 2 g of pure water for a hydrolysis reaction, and 0.1 g of 1N nitric acid as a reaction catalyst were mixed, and then 60 ° C. And stirred for 3 hours to obtain a surface-modified mesoporous silica dispersion.

"Composition for forming low refractive index film"
The obtained surface-modified mesoporous silica dispersion was added to the solvent of Production Example 3 so that the amount of SiO ₂ was 0.8% by mass and EXP-07 was 1.2% by mass, and Irgacure 127 was further added to SiO _2. 3% by mass with respect to the total mass of EXP-07 and mixed, to obtain a composition for forming a low refractive index film. The refractive index of the cured product of the composition for forming a low refractive index film was measured by a prism coupler (manufactured by Metricon) and found to be 1.41. EXP-07 includes a crosslinkable compound having one or more methacryloyl groups or acryloyl groups.

"Film formation"
The obtained composition for forming a low refractive index film was coated on both sides of Delaglass A (acrylic sheet) by dip coating so that the dry film thickness was 100 nm, and dried by heating at 60 ° C. for 5 minutes. Next, a low-refractive index film having anti-fingerprint properties is formed by forming a film by exposing and curing ultraviolet rays from both sides of Delaglass A so as to have an energy of 300 mJ / cm ^{2 with} a high-pressure mercury lamp (120 W / cm). An acrylic sheet (plastic substrate) was obtained.

[Example 2]
An acrylic sheet provided with a low refractive index film having fingerprint resistance was prepared in the same manner as in Example 1 except that one side of Delaglass A in Example 1 was masked with a masking film. Next, the masked film was removed, and the film was left only on the acrylic sheet surface on one side, whereby an acrylic sheet provided with a low refractive index film having anti-fingerprint properties on only one side was obtained.

[Example 3]
The composition for forming a hard coat film of Production Example 4 was coated on both sides of Delaglass A by dip coating so that the dry film thickness was 3 μm, and dried by heating at 60 ° C. for 5 minutes. Next, ultraviolet rays were exposed from both sides of Delaglass A so as to have an energy of 300 mJ / cm ^{2 with} a high-pressure mercury lamp (120 W / cm) to cure the coating film, thereby obtaining an acrylic sheet with a hard coat film.

Next, the composition for forming a low refractive index film prepared in Example 1 is applied to the obtained acrylic sheet with a hard coat film by the same method as in Example 1 and cured, thereby improving fingerprint resistance. An acrylic sheet with a hard coat film provided with a low refractive index film was obtained.

[Example 4]
"Composition for forming low refractive index film"
A composition for forming a low refractive index film was obtained in the same manner as in the production procedure of Example 1, except that 1.2% by mass of FH-700 was added instead of EXP-07. The refractive index of the cured product of the composition for forming a low refractive index film was measured by a prism coupler (manufactured by Metricon) and found to be 1.41. FH-700 includes a crosslinkable compound having one or more methacryloyl or acryloyl groups.

"Membrane formation"
In the formation procedure of Example 3, instead of using the composition for forming a low refractive index film prepared in Example 1, the composition for forming a low refractive index film obtained in Example 4 was used in the same manner. An acrylic sheet with a hard coat film provided with a low refractive index film having fingerprint resistance was obtained.

[Example 5]
"Preparation of a composition for forming a low refractive index film"
A composition for forming a low refractive index film was obtained in the same manner as in the production procedure of Example 1, except that DPHA was used at 1.1 mass% and F-444 was used at 0.1 mass% instead of EXP-07. It was. The refractive index of the cured product of the composition for forming a low refractive index film was measured by a prism coupler (manufactured by Metricon) and found to be 1.41. DPHA includes a crosslinkable compound having one or more methacryloyl or acryloyl groups.

"Membrane formation"
In the formation procedure of Example 3, instead of the composition for forming a low refractive index film prepared in Example 1, the same procedure was used except that the composition for forming a low refractive index film obtained in Example 5 was used. An acrylic sheet with a hard coat film provided with a low refractive index film having fingerprint resistance was obtained.

[Example 6]
"Surface modification of low refractive index inorganic fine particles"
A surface-modified mesoporous silica dispersion was obtained in the same manner as in the production procedure of Example 1, except that KBM-503 having a methacryloyloxy group was used as a surface treatment agent instead of KBM-5103.

"Preparation of a composition for forming a low refractive index film"
In the same procedure as in Example 1, except that the surface-modified mesoporous silica dispersion obtained in Example 6 was used in place of the surface-modified mesoporous silica dispersion in Example 1, a low refractive index film was formed. A composition was obtained. The refractive index of the cured product of the composition for forming a low refractive index film was measured by a prism coupler (manufactured by Metricon) and found to be 1.41.

"Membrane formation"
In the formation procedure of Example 3, in place of the composition for forming a low refractive index film prepared in Example 1, except that the composition for forming a low refractive index film obtained in Example 6 was used, An acrylic sheet with a hard coat film provided with a low refractive index film having fingerprint resistance was obtained.

[Example 7]
In the production procedure of Example 3, in the same manner as in Example 4 except that the composition for forming a conductive hard coat film obtained in Production Example 5 was used instead of the composition for forming a hard coat film of Production Example 4, anti-fingerprinting An acrylic sheet with a conductive hard coat film provided with a low refractive index film having the property was obtained. That is, a low refractive index film having fingerprint resistance is provided in the same manner as in Example 1 except that an acrylic sheet with a conductive hard coat film using the conductive hard coat film forming composition of Production Example 5 is used. An acrylic sheet with a conductive hard coat film was obtained.

[Example 8]
The composition for forming a hard coat film of Production Example 4 was coated on both sides of Delaglass A by dip coating so that the dry film thickness was 3 μm, and dried by heating at 60 ° C. for 5 minutes. Next, ultraviolet rays were exposed from both sides of Delaglass A so as to have an energy of 300 mJ / cm ^{2 with} a high-pressure mercury lamp (120 W / cm) to cure the coating film, thereby obtaining an acrylic sheet with a hard coat film. Next, on the obtained acrylic sheet with a hard coat film, the high refractive index paint obtained in Production Example 6 was coated on both sides by dip coating so that the dry film thickness was 100 nm, and heated at 60 ° C. for 5 minutes. Dried. Next, the low refractive index film-forming composition of Example 1 was applied and cured in the same manner as in Example 1 to provide a low refractive index film and a high refractive index film having anti-fingerprint properties. An acrylic sheet with a hard coat film was obtained.

[Example 9]
"Composition for forming low refractive index film"
The low refractive index film formation was performed in the same manner as in the production procedure of Example 1, except that the mesoporous silica dispersion obtained in Production Example 1 was used instead of the surface-modified mesoporous silica dispersion obtained in Example 1. A composition was obtained. The refractive index of the cured product of the composition for forming a low refractive index film was measured by a prism coupler (manufactured by Metricon) and found to be 1.41.

"Film formation"
In the formation procedure of Example 3, instead of the composition for forming a low refractive index film prepared in Example 1, except that the composition for forming a low refractive index film obtained in Example 9 was used, An acrylic sheet with a hard coat film provided with a low refractive index film having fingerprint resistance was obtained.

[Example 10]
"Composition for forming low refractive index film"
A low refractive index was similarly obtained except that colloidal silica (IPA-st manufactured by Nissan Chemical Industries, Ltd.) was used in place of the surface-modified mesoporous silica dispersion obtained in Example 1 in the production procedure of Example 1. A film forming composition was obtained. The refractive index of the cured product of the composition for forming a low refractive index film was measured by a prism coupler (manufactured by Metricon) and found to be 1.46.

"Membrane formation"
In the formation procedure of Example 3, instead of using the composition for forming a low refractive index film prepared in Example 1, the same procedure was used except that the composition for forming a low refractive index film obtained in Example 10 was used. An acrylic sheet with a hard coat film provided with a low refractive index film having fingerprint resistance was obtained.

[Comparative Example 1]
"Composition for forming low refractive index film"
A composition for forming a low refractive index film was obtained in the same manner as in the production procedure of Example 1, except that DPHA was used instead of EXP-07. The refractive index of the cured product of the composition for forming a low refractive index film was measured by a prism coupler (manufactured by Metricon) and found to be 1.41. This composition does not contain a compound having a perfluoro group and having no photoreactive functional group.

"Membrane formation"
In the formation procedure of Example 3, instead of using the composition for forming a low refractive index film prepared in Example 1, the composition for forming a low refractive index film obtained in Comparative Example 1 was used in the same manner. An acrylic sheet with a hard coat film provided with a low refractive index film was obtained.

[Comparative Example 2]
"Composition for forming low refractive index film"
Instead of using 0.8% by mass of the surface-modified mesoporous silica dispersion in terms of SiO ₂ and 1.2% by mass of EXP-07 in the production procedure of Example 1, 2. A composition for forming a low refractive index film containing no inorganic fine particles was obtained in the same manner except that 0% by mass was used. The refractive index of the cured product of the composition for forming a low refractive index film was measured by a prism coupler (manufactured by Metricon), and was 1.50.

"Membrane formation"
In the formation procedure of Example 3, a film having fingerprint resistance was similarly obtained except that the composition obtained in Comparative Example 2 was used instead of the composition for forming a low refractive index film prepared in Example 1. An acrylic sheet provided with a hard coat film was obtained.

Each of the acrylic sheet obtained in each of Examples 1 to 10 and Comparative Examples 1 and 2 was evaluated for the anti-fingerprint property, transparency, visible light reflectance, conductivity, and steel wool resistance by the following methods. . The evaluation results are shown in Table 2.

(1) Evaluation of fingerprint resistance (trioleic acid wiping evaluation)
One drop of trioleic acid was dropped on the film and wiped 10 times with a clean wiper. The haze (%) of the film before the trioleic acid was dropped and after 10 reciprocations were measured using a haze meter TC-1800MK / II (manufactured by Nippon Denshoku), and the haze before the trioleic acid was dropped. And the difference between the haze after wiping 10 times (Δhaze value). Trioleic acid is one of the main components of fingerprints, and the lower the adhesion, the better the fingerprint resistance.

According to the obtained Δhaze value, the anti-fingerprint property was evaluated based on the following criteria. The haze (%) is a value measured through Delaglass A, which is an acrylic sheet having a thickness of 1 mm used as a base material for film formation. The smaller the Δhaze value, the better.
A: Δhaze value is less than 0.5 B: Δhaze value is 0.5 or more and less than 1.0 C: Δhaze value is 1.0 or more and less than 3.0 D: Δhaze value is 3.0 or more And less than 5.0 E: Δhaze value is 5.0 or more

(2) Evaluation of transparency The total light transmittance (T (%)) of the film was measured using a haze meter TC-1800MK / II (manufactured by Nippon Denshoku). At that time, the difference ΔT value of the total light transmittance measured by interposing the untreated Delaglass A without the film and Delaglass A used as the base material in each film (total light transmittance of the film + the base material− The total light transmittance of the substrate was calculated. According to the obtained ΔT value, transparency was evaluated according to the following criteria. A larger ΔT value is preferable.
A: ΔT value is +3.0 or more B: ΔT value is 0.0 or more and less than +3.0 C: ΔT value is −0.6 or more and less than 0.0 D: ΔT value is less than −0.6

(3) Evaluation of visible light reflectance The 10 ° regular reflectance of the film was measured using a spectrophotometer U-4100 (manufactured by Hitachi, Ltd.). The visible light reflectance of the film was calculated by multiplying the obtained measured value by the specific visibility value. The smaller the visible light reflectance, the better.

(4) Evaluation of conductivity The surface resistance of the film was measured using a resistivity meter Loresta AP (manufactured by Mitsubishi Chemical Corporation). According to the obtained surface resistance value, the conductivity was evaluated according to the following criteria.
A: Less than 1 × 10 ⁹ Ω / □ B: 1 × 10 ⁹ Ω / □ or more and less than 1 × 10 ¹¹ Ω / □ C: 1 × 10 ¹¹ Ω / □ or more and less than 1 × 10 ¹³ Ω / □ D: 1 × 10 ¹³ Ω / □ or more

(5) Evaluation of steel wool resistance On the membrane, steel wool (# 0000) was reciprocated 10 times under a load of 250 g / cm ² (1 reciprocation: 200 mm). Thereafter, the surface of the film was visually evaluated. Here, the steel wool resistance was evaluated according to the following criteria. The fewer scratches, the better.
A: Almost no scratches (no more than 5mm scratches)
B: 2 or less scratches C: 3 or more scratches, 10 or less D: 11 or more scratches

(6) Evaluation of water repellency The contact angle of water was measured using a contact angle meter CA-X (manufactured by Kyowa Interface Chemical Co., Ltd.) and evaluated according to the following criteria. The larger the contact angle of water, the higher the water repellency and the adhesion of dirt can be prevented.
○: 90 degrees or more Δ: 85 degrees or more and less than 90 degrees ×: less than 85 degrees

(7) Evaluation of lipophilicity The contact angle of hexadecane was measured using a contact angle meter CA-X (manufactured by Kyowa Interface Chemical Co., Ltd.) and evaluated according to the following criteria. When it is less than 40 °, it can be preferably used as a water-repellent and lipophilic film.
○: Less than 30 degrees △: 30 degrees or more and less than 40 degrees ×: 40 degrees or more

According to the present invention, it is possible to provide a composition for forming a low refractive index film having fingerprint resistance, excellent antireflection properties, and excellent film strength such as scratch resistance.

DESCRIPTION OF SYMBOLS 10 Plastic base material provided with low refractive index film | membrane 11 Plastic base material 12 Low refractive index film | membrane 13 Hard coat film | membrane 14 High refractive index film | membrane 100 Display apparatus 101 Case 102 Display part

Claims (9)

1. A crosslinkable compound having at least one methacryloyl group or acryloyl group in the monomer;
   A compound having a perfluoro group and having no photoreactive functional group, and inorganic particles having a refractive index of 1.17 or more and 1.40 or less,
   A composition for forming a low refractive film, comprising:
2. The composition for forming a low refractive film according to claim 1, wherein the inorganic particles are modified with an organic group containing at least one of an acryloyloxy group and a methacryloyloxy group on the particle surface.
3. The composition for forming a low refractive film according to claim 1, wherein the average primary particle diameter of the inorganic particles is 3 nm or more and 100 nm or less.
4. The composition for forming a low refractive film according to claim 1, wherein the inorganic particles are mesoporous silica fine particles.
5. A low refractive index film formed by the composition for forming a low refractive film according to claim 1.
6. A plastic substrate comprising the low refractive index film according to claim 5 on a plastic substrate.
7. A display device comprising the low refractive index film according to claim 5 on a display surface.
8. The display device according to claim 7, wherein the low refractive index film is provided on a plastic substrate.
9. Use of the composition for forming a low refractive film according to claim 1 for forming a low refractive film.

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