JP4614813B2 - Low refractive index film-forming composition and cured film-coated substrate - Google Patents

Description

  The present invention relates to a composition for forming a low refractive index film used for optical applications such as an antireflection film and a substrate with a cured film thereof. More specifically, a low refractive index excellent in scratch resistance, chemical resistance, and transparency comprising a perfluoro group-containing (meth) acrylic ester resin and hollow silica fine particles treated with a specific silane coupling agent. The present invention relates to a film-forming composition and a substrate with a cured film excellent in scratch resistance, chemical resistance, transparency, antireflection performance and the like.

Conventionally, a cured film having transparency, such as an antireflection film, has been widely applied to display devices such as CRT displays, liquid crystal displays (LCDs), plasma displays (PDPs), optical parts such as glasses, optical lenses, and optical filters. in use. As a low refractive index material generally used for an antireflection film or the like, a fluorine-based compound and a silicon-based compound can be given.
However, although the fluorine-based compound has a low refractive index and excellent chemical resistance and transparency, there is a problem that the scratch resistance is low.

  On the other hand, silicon-based compounds are superior in scratch resistance as compared to fluorine-based compounds, but have a problem that their refractive index is not so low and chemical resistance to acids, alkalis, and the like is low. Therefore, it has been proposed to use a fluorine-based compound and a silicon-based compound in combination, but they are not compatible or dispersible with each other, and it is difficult to obtain a uniform film. There are methods such as reducing the ratio or surface-treating a silicon-based compound. However, in either case, the effect of reducing the refractive index and improving the antireflection performance tends to be insufficient. In addition, it may be difficult to obtain a cured film having scratch resistance, transparency, and chemical resistance.

In JP-A-2003-313242 (Patent Document 1), when a perfluoro group-containing (meth) acrylic ester resin is used, a cured film having excellent scratch resistance, chemical resistance, heat resistance and the like can be obtained. It is disclosed.
JP-A-2004-238487 (Patent Document 2) discloses that when a perfluoro group-containing (meth) acrylic ester resin is used, a cured film having a high hardness and a high glass transition temperature and a low refractive index can be obtained. Has been. However, the conventional base material with a cured film has a drawback that the antireflection performance is insufficient and the reflection is strong when used as a protective film of a display device, and the image is difficult to see.

  In JP-A-2001-233611 (Patent Document 3), a transparent film in which silica-based fine particles having a low refractive index are blended as a silicon compound is excellent in adhesion to a substrate and has a low refractive index and antireflection performance. It is disclosed that it is excellent. However, when used in combination with a highly hydrophobic fluorine compound to further improve the antireflection performance, the coating stability is low as described above, resulting in a non-uniform film or whitening. There was a case.

As a result of intensive studies, the inventors of the present application have found that a low refractive index containing a perfluoro group-containing (meth) acrylate resin and hollow silica-based fine particles substantially free of alkali treated with a specific silane coupling agent. The composition for forming a rate film is excellent in the stability of a paint, and a cured film formed using the composition has been found to be excellent in antireflection performance and scratch resistance, thereby completing the present invention.
JP 2003-313242 A JP 2004-238487 A JP 2001-233611 A

  The present invention has been made to solve the above-mentioned problems, and is a composition for forming a low refractive index film, which is excellent in scratch resistance, chemical resistance, transparency, antireflection performance and the like particularly useful as an antireflection film. Another object of the present invention is to provide a substrate with a cured film that is excellent in scratch resistance, chemical resistance, transparency, antireflection performance, and the like obtained by using the composition.

The composition for forming a low refractive index film according to the present invention comprises a perfluoro group-containing (meth) acrylate resin and hollow silica-based fine particles treated with a silane coupling agent represented by the following formula (I): It is characterized by becoming.
R _n SiX _(4-n)・ ・ ・ ・ ・ ・ （I）
(However, R: C1-C4 alkoxy group, methacryloyloxy group, acryloyloxy group, perfluoro (meth) acryloyl group, X: C1-C4 alkoxy group, silanol group, halogen or hydrogen)

The perfluoro group-containing (meth) acrylic ester resin is preferably a compound represented by the following chemical formula (II) or (III).
_{(C p F q -O) r} -A - (- O-CO-CR = CH 2) S ······ (II)
(In the formula (II), p is 1 to 18, q is 3 to 37, r + s is 3 to 20, r is 1 to 18, s is an integer of 2 to 19, and -A- is the residual hydroxyl group of the polyhydric alcohol. Group R represents a hydrogen atom or a methyl group.)
(R ^1- ) _x- (C _l H _m F _n )-{(CH ₂ ) _y -O-CO-C (-R ² ) = CH ₂ } _z (III)
(In the formula (III),-(C _l H _m F _n )-is an alicyclic group in which l is 3 to 10, m is 0 to 4, and n is 2 to 18, x is 0 to 8, y is (0 to 4, z is 2 to 6, R ¹ -represents a linear or branched alkyl group or fluoroalkyl group having 1 to 10 carbon atoms, and -R ² represents a hydrogen atom or a methyl group.)

The content of ammonia and / or ammonium ions in the hollow silica-based fine particles is preferably 2500 ppm or less as NH ₃ .
The content of alkali in the hollow silica-based fine particles is preferably 3 ppm or less as M _A2 O (M _A : alkali metal element).
Further, it preferably contains a non-fluorine-containing polyfunctional (meth) acrylic ester.
The hollow silica-based fine particles preferably have an average particle diameter in the range of 5 to 500 nm and a refractive index in the range of 1.15 to 1.40.
The hollow silica fine particles are composed of silica and an inorganic oxide other than silica, and the molar ratio MO _X / SiO ₂ is 0.0001 when the silica is expressed by SiO ₂ and the inorganic oxide other than silica is expressed by MO _X. It is preferable to be in the range of ~ 0.2.

The base material with a cured film according to the present invention is formed on the surface of the base material alone or together with another film, using the composition for forming a low refractive index film according to any one of claims 1 to 7. It is characterized by.
The refractive index of the cured film is preferably in the range of 1.20 to 1.40, and the film thickness is preferably in the range of 0.01 to 10 μm.

  According to the present invention, a treatment with a perfluoro group-containing (meth) acrylic ester resin and a silane coupling agent containing any of an alkoxy group, a methacryloyloxy group, an acryloyloxy group, and a perfluoro (meth) acryloyl group Since the hollow silica-based fine particles are contained, they are cross-linked and polymerized in a three-dimensional network, and thus have excellent scratch resistance, chemical resistance, transparency, and low refractive index and excellent antireflection performance. A composition for forming a low refractive index film that can be suitably used for forming a film, and a substrate with a cured film excellent in scratch resistance, chemical resistance, transparency, and antireflection performance can be provided.

Hereinafter, preferred embodiments of the present invention will be described.
First, the composition for forming a low refractive index film according to the present invention will be described.
[Composition for forming low refractive index film]
The composition for forming a low refractive index film according to the present invention comprises a perfluoro group-containing (meth) acrylate resin and hollow silica-based fine particles treated with a silane coupling agent represented by the following formula (I): It is characterized by becoming.
R _n SiX _(4-n)・ ・ ・ ・ ・ ・ （I）
(Where, R: an alkoxy group having 1 to 4 carbon atoms, methacryloyloxy group, acryloyloxy group, perfluoro (meth) acryloyl group, X: an alkoxy group having 1 to 4 carbon atoms, a silanol group, halogen or hydrogen)

1. Perfluoro group-containing (meth) acrylate resin The perfluoro group-containing (meth) acrylate resin used in the composition for forming a low refractive index film of the present invention is a compound represented by the following chemical formula (II) or (III) It is preferable that

_{(C p F q -O) r} -A - (- O-CO-CR = CH 2) S ······ (II)
(In the formula (II), p is 1 to 18, q is 3 to 37, r + s is 3 to 20, r is 1 to 18, s is an integer of 2 to 19, and -A- is the dehydroxylation residue of the polyhydric alcohol. Group R represents a hydrogen atom or a methyl group.)

The polyhydric alcohol (HO-) _r -A-(-OH) _s is pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, diglycerin, triglycerin, polyglycerin, trimethylolpropane, ditrimethylolpropane, tritriol. Any alcohol of methylolethane or ditrimethylolethane, ethylene oxide adduct of these alcohols, propylene oxide adduct of these alcohols, butylene oxide adduct of these alcohols, or ε -caprolactone modified product of these alcohols Although it is preferable, it is not limited to these.
In the chemical formula (II), the perfluoro group C _p F _q- may be saturated or unsaturated, linear or branched, and cyclic having an alicyclic ring or an aromatic ring. There may be. It is more preferable that p is 6 to 12 and q is 11 to 25.
Among these, C _p F _q -is more preferably a perfluoro group represented by the following formula (IV).

As such a perfluoro group-containing (meth) acrylic ester resin, specifically, light acrylate PE-3A (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), which is pentaerythritol triacrylate, is substituted with a perfluoro group. Triacryloyl-heptadecafluorononenyl-pentaerythritol.
The perfluoro group-containing (meth) acrylic ester resin is prepared, for example, as follows.

The case where the polyhydric alcohol is pentaerythritol and the perfluoro group C _p F _q -is the heptadecafluorononenyl group of the formula (IV) will be described as an example. When one equivalent of perfluorononene (2) is reacted with pentaerythritol triacrylate (1), perfluorononene (2) remains as a by-product of hydrogen fluoride as shown in chemical reaction formula (V). The perfluoro group-containing (meth) acrylic acid ester (3) is obtained by reacting with the hydroxyl group.

  In addition, a mixture of mono-, di-, tri-, and tetra- (meth) acrylate is obtained by esterification reaction of pentaerythritol and (meth) acrylic acid, and this is reacted with perfluorononene. A mixture of mono- to tetra- (meth) acrylic ester resins containing a fluoro group may be used. In the case of such a mixture, it is preferable that 40% or more of (meth) acrylic acid ester containing one perfluoro group per molecule is contained in the mixture.

(R ^1- ) _x- (C _l H _m F _n )-{(CH ₂ ) _y -O-CO-C (-R ² ) = CH ₂ } _z (III)
(In the formula (III),-(C _l H _m F _n )-is an alicyclic group in which l is 3 to 10, m is 0 to 4, and n is 2 to 18, x is 0 to 8, and y is (0 to 4, z is 2 to 6, R ¹ -represents a linear or branched alkyl group or fluoroalkyl group having 1 to 10 carbon atoms, and -R ² represents a hydrogen atom or a methyl group.)
The alicyclic group — (C ₁ H _m F _n ) — is a 3- to 10-membered ring, which may have an unsaturated group, an alkyl group branched from the ring, or a side chain of a fluoroalkyl group. It may be a geometric isomer or an optical isomer.
Specifically, the alicyclic group — (C ₁ H _m F _n ) — is preferably a perfluoroalicyclic group exemplified by the following group (VI), (VII) or (VIII).

In addition, — {(CH ₂ ) _y —O—CO—C (—R ² ) ═CH ₂ } _z bonded to this group may be in a cis-configuration or / and a trans-configuration.
Such a perfluoro group-containing (meth) acrylic acid ester resin is obtained by, for example, reacting an alicyclic polyol with a fluorinating agent, or reacting an alicyclic compound with a fluorinating agent and then oxidizing or reducing as appropriate. , A fluorine-substituted alicyclic group-containing polyol, and (meth) acrylic acid obtained by dehydration and esterification in the presence of an acid catalyst.
The fluorine-substituted alicyclic group-containing acrylate ester represented by (C ₆ F ₁₀ ) — (CH ₂ —O—CO—CH═CH ₂ ) ₂ having the group (VI) will be specifically described by way of example. It is obtained by fluorinating phthalic acid with fluorine gas, reducing with lithium aluminum hydride (LiAlH ₄ ), and then esterifying with acrylic acid.

When these perfluoro group-containing (meth) acrylic acid ester resins are irradiated with active energy rays, the contained (meth) acrylic acid ester groups rapidly cross-link and polymerize in a three-dimensional network to make them strong and scratch-resistant. An excellent cured film is formed, and the cured film can be suitably used because a perfluoro group having a low surface energy is exposed on the surface thereof and the refractive index is low and the chemical resistance is excellent.
In addition, the compound represented by the chemical formula (II) or (III) may be mixed and used as necessary.

The molecular weight of the perfluoro group-containing (meth) acrylic ester resin is preferably in the range of 300 to 5000, more preferably 300 to 3000.
When the molecular weight of the perfluoro group-containing (meth) acrylic acid ester is less than 300, the fluorine content decreases and the refractive index becomes insufficient.
If the molecular weight of the perfluoro group-containing (meth) acrylic acid ester exceeds 5000, the content of the (meth) acrylic acid ester group is lowered and the scratch resistance becomes insufficient. This molecular weight is a value in terms of polystyrene measured by a GPC (gel permeation chromatography) method.

The perfluoro group-containing (meth) acrylic acid ester resin may be further mixed with a non-fluorine-containing polyfunctional (meth) acrylic acid ester resin.
At this time, the non-fluorine-containing polyfunctional (meth) acrylic ester resin is not particularly limited, but in consideration of curability and scratch resistance, pentaerythritol triacrylate, trimethylolpropane tri (meth) acrylate, Tri- or higher functional (meth) acrylic ester resins such as pentaerythritol tetraacrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol hexaacrylate and the like are particularly preferable.

The content of these non-fluorine-containing polyfunctional (meth) acrylic ester resins is preferably 1 to 50% by weight, and more preferably 2 to 20% by weight within a range that does not adversely affect physical properties such as refractive index. The content mentioned here is a non-fluorine-containing polyfunctional (meth) acrylic acid ester when a perfluoro group-containing (meth) acrylic acid ester and a non-fluorine-containing polyfunctional (meth) acrylic acid ester are mixed and used. Is the ratio.
When these non-fluorine-containing polyfunctional (meth) acrylic ester resins are mixed and used, the scratch resistance, hardness and the like of the resulting cured film can be further improved.

2. Hollow silica-based fine particles Next, the hollow silica-based fine particles used in the present invention have a content of ammonia and / or ammonium ions in the hollow silica-based fine particles of 2500 ppm or less, further 1000 ppm or less, particularly 400 ppm or less as NH _3. Is preferred.
When the content of ammonia and / or ammonium ions in the hollow silica fine particles exceeds 2500 ppm as NH ₃ , the stability is poor when mixed with a perfluoro group-containing (meth) acrylate resin, and aggregation and gelation occur. Even if it is apparently dispersed, the film may be whitened.
In the case where the hollow silica-based fine particles are used as a dispersion, the total content of ammonia and / or ammonium ions including the ammonia and / or ammonium ions in the dispersion medium is present in the hollow silica-based fine particles. It is preferable to be in the range.

Further, the alkali content in the hollow silica-based fine particles is preferably 3 ppm or less, particularly 2 ppm or less, as M _A2 O (M _A : alkali metal element).
When the content of alkali in the hollow silica fine particles exceeds 3 ppm as M _A2 O, the coating composition for coating film formation has insufficient stability and high viscosity when mixed with a perfluoro group-containing (meth) acrylate resin. As a result, the film formability is lowered, the strength of the resulting film is insufficient, and the film thickness may be uneven.
In addition, when using a hollow silica type microparticle as a dispersion liquid, it is preferable to exist in the said range as content of the total alkali including the alkali in a dispersion medium exists in a hollow silica type microparticle.

Next, when an alkaline earth metal is contained in the hollow silica fine particle or in the hollow silica fine particle dispersion, the alkaline earth is contained in the hollow silica fine particle or in the hollow silica fine particle dispersion as in the case of the alkali metal. The amount is preferably 3 ppm or less, particularly 2 ppm or less as M _E O (M _E : alkaline earth metal element).

Next, the average particle diameter of the hollow silica-based fine particles is preferably in the range of 5 to 500 nm, more preferably 20 to 150 nm.
When the average particle diameter of the hollow silica fine particles is less than 5 nm, it is difficult to form cavities inside the particles, and even if the cavities are obtained, the refractive index may not be lowered sufficiently.
When the average particle diameter of the hollow silica fine particles exceeds 500 nm, the resulting cured film may be whitened by particle scattering.

The refractive index of the hollow silica fine particles is preferably in the range of 1.15 to 1.40, more preferably 1.15 to 1.35.
It is difficult to obtain hollow silica fine particles having a refractive index of less than 1.15. Even if it is obtained, the outer layer of the particles is thin and the particles are cracked, or the resin enters the cavity when mixed with the resin. As a result, the refractive index may not be sufficiently lowered.
When the refractive index of the hollow silica fine particles exceeds 1.40, the refractive index of the cured film obtained is insufficiently lowered and sufficient antireflection performance may not be obtained.

The method for measuring the refractive index of the hollow silica fine particles of the present invention was performed by the following method.
(1) Take a dispersion of hollow silica fine particles in an evaporator and evaporate the dispersion medium.
(2) This is dried at 120 ° C. to obtain a powder.
(3) A standard refraction liquid having a known refractive index is dropped on a glass plate of a few drops, and the above powder is mixed therewith.
(4) The operation of (3) above is performed with various standard refractive liquids, and the refractive index of the standard refractive liquid when the mixed liquid (in many cases, paste-like) becomes transparent is used as the refractive index of the fine particles.

The hollow silica-based fine particles are composed of silica and an inorganic oxide other than silica, and the molar ratio MO _X / SiO ₂ is 0.0001 when the silica is expressed by SiO ₂ and the inorganic oxide other than silica is expressed by MO _X. It is preferably in the range of ˜0.2, more preferably 0.005 to 0.1.
Such hollow silica-based fine particles are treated with a silane coupling agent represented by the following formula (I).
R _n SiX _(4-n)・ ・ ・ ・ ・ ・ （I）
(However, R: C1-C4 alkoxy group, methacryloyloxy group, acryloyloxy group, perfluoro (meth) acryloyl group, X: C1-C4 alkoxy group, silanol group, halogen or hydrogen)

Examples of the silane coupling agent containing methacryloyloxy group and acryloyloxy group include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxy. Examples include loxypropyltriethoxysilane and 3-acryloxypropyltrimethoxysilane.
Examples of the silane coupling agent containing a perfluoro (meth) acryloyl group include heptadecatrifluorodecyltrimethoxysilane, heptadecatrifluorodecyltriethoxysilane, heptadecatrifluorodecyltripropoxysilane, and the like. .

  When treated with such a silane coupling agent, it can be easily dispersed in a perfluoro group-containing (meth) acrylate resin having a high fluorine content, that is, a low refractive index, and a lower refractive index. A highly transparent film can be obtained. In addition, the perfluoro group-containing (meth) acrylic ester resin and the perfluoro (meth) acryloyl group, or the hollow silica-based fine particles surface-treated with the (meth) acryloyl group-containing silane coupling agent are crosslinked with each other. Scratch resistance is improved.

  As a method for treating hollow silica fine particles with a silane coupling agent, a conventionally known method can be adopted. For example, a silane coupling agent is added to a dispersion of hollow silica fine particles, and if necessary, hydrolysis is performed. Examples thereof include a method of adding a catalyst and a method in which only a coupling agent is hydrolyzed in advance and added to a hollow silica fine particle dispersion to add a catalyst. Moreover, the said silane coupling agent may be used independently and can also be mixed and used.

3. Method for Producing Hollow Silica Fine Particles As a method for producing such hollow silica fine particles, an outer shell layer is provided, and the inside is porous or hollow, and the refractive index, average particle diameter, and ammonia are in the above ranges. Although there will be no restriction | limiting in particular if it has content, alkali content, etc., The method illustrated below can be employ | adopted suitably.
For example, the composite oxide sol or hollow silica fine particles disclosed in JP-A-7-133105 and JP-A-2001-233611 are obtained by the following steps (a) to (d), which are further hydrothermally treated at a high temperature. be able to.

  As a process (a), the alkali aqueous solution of inorganic raw materials other than a silica raw material and silica is separately prepared beforehand, or both mixed aqueous solution is prepared. Next, according to the composite ratio of the target composite oxide, the obtained aqueous solution is gradually added to an alkaline aqueous solution having a pH of 10 or more while stirring. A dispersion containing seed particles in advance can be used in an alkaline aqueous solution having a pH of 10 or more.

Next, as the step (b), at least a part of elements other than silicon and oxygen is selectively removed from the colloidal particles made of the composite oxide obtained in the step (a). Specifically, the elements in the composite oxide are dissolved and removed using a mineral acid or an organic acid, or are contacted with a cation exchange resin and removed by ion exchange.
Subsequently, as a step (c), the surface of the colloidal particles is hydrolyzed by adding a hydrolyzable organosilicon compound or silicic acid solution to the composite oxide colloidal particles from which some of the elements have been removed. Cover with a polymer such as a silicon compound or silicic acid solution. In this way, the complex oxide sol described in the above publication can be produced.

Next, as the step (d), the composite oxide sol or hollow silica fine particles obtained above is hydrothermally treated in the range of 50 to 300 ° C.
The composite oxide sol or hollow silica fine particles obtained by the above step (c) contains ionic impurities. These impurities are derived from raw materials, additives added in the manufacturing process, and the like. By removing such ionic impurities by hydrothermal treatment, the amount of impurities in the obtained hollow silica fine particles is set to a predetermined amount or less.

When the hydrothermal treatment temperature is less than 50 ° C., the content of alkali metal oxide and / or ammonia in the finally obtained hollow silica fine particles cannot be effectively reduced, and the composition for forming a low refractive index film The effect of improving the stability of the product and film formation is insufficient, and the strength of the resulting coating is also insufficiently improved.
Even when the hydrothermal treatment temperature exceeds 300 ° C., the stability, film-forming property, film strength, etc. of the coating film-forming coating material are not further improved, and in some cases, the hollow silica-based fine particles may aggregate.

  Furthermore, the said process (d) can also be repeated as needed. Further, deionization treatment can be performed with an ion exchange resin or the like before and / or after hydrothermal treatment. As the ion exchange resin, a cation exchange resin, an anion exchange resin, or both ion exchange resins can be used, and ammonia and alkali can be effectively reduced by deionizing with an ion exchange resin or the like.

The content of ammonia and / or ammonium ions in the hollow silica-based fine particles thus obtained is preferably 2500 ppm or less, more preferably 1000 ppm or less, and particularly preferably 400 ppm or less as NH ₃ .
Further, the alkali content in the hollow silica-based fine particles is preferably 3 ppm or less, particularly 2 ppm or less, as M _A2 O (M _A : alkali metal element).

4). Silane coupling treatment The resulting hollow silica fine particles are then treated with a silane coupling agent represented by the following formula (I).
R _n SiX _(4-n)・ ・ ・ ・ ・ ・ （I）
(However, R: alkoxy group, methacryloyloxy group, acryloyloxy group, perfluoro (meth) acryloyl group, X: C 1-4 alkoxy group, silanol group, halogen or hydrogen)
The same silane coupling agent as described above can be used.

As a method for treating hollow silica fine particles with a silane coupling agent, a conventionally known method can be employed. For example, a silane coupling agent is added to a dispersion of hollow silica fine particles, and an acid or alkali is added as necessary. Can be added as a catalyst for hydrolysis.
The treatment amount of the silane coupling agent to the hollow silica fine particles is preferably in the range of 5 to 100% by weight, particularly 10 to 50% by weight, based on the hollow silica fine particles. Further, the silane coupling agent may be used alone or in combination, and further, a silane coupling agent hydrolyzed with an acid or alkali in advance may be used.

When the treatment amount of the silane coupling agent to the hollow silica fine particles is less than 5% by weight, the particle surface is not uniformly treated, and the dispersibility in the perfluoro group-containing (meth) acrylate resin becomes insufficient. Even if it is made into a paint, it may agglomerate, or even if a film is obtained, it may be whitened.
On the other hand, if it exceeds 100% by weight, the refractive index of the hollow silica-based fine particles may increase, may not precipitate efficiently on the particle surface, or may generate other fine particles.

5. Low-refractive-index film-forming composition The low-refractive-index film-forming composition of the present invention comprises the perfluoro group-containing (meth) acrylic ester resin and a non-fluorine-containing polyfunctional (meth) acrylic acid used as necessary. The ester resin is preferably contained in the obtained cured film so that the solid content is in the range of 10 to 90% by weight, more preferably 30 to 60% by weight.
When the content of such a resin is less than 10% by weight, the resulting cured film has insufficient scratch resistance and chemical resistance so that the solid content in the obtained cured film exceeds 90% by weight. When it contains, the refractive index of the cured film obtained becomes inadequate, and the outstanding antireflection performance is not obtained.

Further, the composition for forming a low refractive index film comprises 10 to 90% by weight, further 40 to 70% by weight, as a solid content, of hollow silica fine particles surface-treated with the silane coupling agent. It is preferable to contain so that it may become the range.
When the content of the hollow silica-based fine particles is less than 10% by weight, the refractive index of the coating is not sufficiently lowered and excellent antireflection performance may not be obtained, or hard coat properties may not be imparted and scratch resistance may not be improved. is there. In addition, the scratch resistance is low.
When the content of the hollow silica fine particles exceeds 90% by weight, the obtained cured film has insufficient transparency, chemical resistance, scratch resistance, and the like.

The composition for forming a low refractive index film of the present invention may further contain a polymerization initiator. As a polymerization initiator, what generate | occur | produces a polymerizable radical by ultraviolet irradiation is mentioned, for example. Specifically, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxycy-2-methyl-1-phenylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 -Acetophenone initiator typified by benzoin, benzoin 2,2-dimethoxy-1,2-diphenylethane-1-one benzoin initiator typified by benzophenone, [4- (methylphenylthio) phenyl] phenyl Benzophenone initiators typified by methane, 4-hydroxybenzophenone, 4-phenylbenzophenone, 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone, 2-chlorothioxanthone, 2,4- Examples thereof include thioxanthone initiators typified by diethyl thioxanthone. Further, as a reaction accelerator, for example, tertiary amines such as p-dimethylaminobenzoic acid ethyl ester and p-dimethylaminobenzoic acid isoamyl ester may be used in combination.
These polymerization initiators and reaction accelerators are preferably contained in an amount of 0.01 to 20% by weight in the composition for forming a low refractive index film.

The composition for forming a low refractive index film of the present invention may further contain an organic solvent. The organic solvent that can be used is not particularly limited. For example, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, alcohol solvents such as methanol, ethanol, isopropyl alcohol, polypropylene glycol monomethyl ether, polypropylene glycol monoethyl ether And polyalkylene glycol ether solvents such as polyethylene glycol monomethyl acetate.
The composition for forming a low refractive index film of the present invention further comprises an additive component such as silicon or fluorine to further improve additional functions such as water repellency, oil repellency and antifouling property to the cured film. It may be contained.

[Base material with cured film]
Below, the base material with a cured film which concerns on this invention is demonstrated.
6). The base material with a cured film The base material with a cured film according to the present invention is used on the surface of the base material alone or together with other coatings using the composition for forming a low refractive index film according to any one of claims 1 to 7. It is characterized by being formed.
Examples of the substrate used in the present invention include a plastic substrate such as polyethylene terephthalate, cyclopolyolefin, triacetyl cellulose, methyl methacrylate, and polycarbonate, or a glass substrate.

The refractive index of the cured film is preferably in the range of 1.20 to 1.40, more preferably 1.25 to 1.38.
It is difficult to obtain a cured film having a refractive index of less than 1.20, and when the refractive index of the cured film exceeds 1.40, the antireflection performance becomes insufficient.
The cured film preferably has a thickness in the range of 0.01 to 10 μm, more preferably 0.03 to 1.0 μm.
When the thickness of the cured film is less than 0.01 μm, the antireflection performance is insufficient and the film has low scratch resistance. When the thickness of the cured film exceeds 10 μm, although scratch resistance is obtained, the antireflection performance is insufficient.

The content of the perfluoro group-containing (meth) acrylic acid ester resin in the cured film and the non-fluorine-containing polyfunctional (meth) acrylic acid ester resin used as necessary is 10 to 90% by weight, more preferably 30 to 60% by weight. %, And the content of the hollow silica fine particles surface-treated with the silane coupling agent is preferably 10 to 90% by weight, more preferably 40 to 70% by weight.
Such a substrate with a cured film may be further provided with another coating, and examples of the other coating include a hard coat film, a high refractive index film, and a conductive film.

7). Manufacturing method of base material with cured film The base material with cured film of the present invention is not particularly limited as long as the base material with cured film is obtained. For example, the base material with a cured film can be manufactured by the following method.
First, the low-refractive-index film forming composition described in any one of claims 1 to 7 is applied onto the above-described base material, dried as necessary, and then cured.
Examples of the coating method include a dipping method, a spray method, a spinner method, a roll coater method, a gravure coater method, and a micro gravure coater method.
Among these, the roll coater method, the gravure coater method, and the micro gravure coater method are preferable because they can be continuously coated and are excellent in productivity.

Next, drying is performed. As a drying method, there is no particular limitation as long as the organic solvent can be removed when an organic solvent is used, and a conventionally known method can be adopted. For example, the method of drying at 60-80 degreeC using a heat circulation furnace or an infrared furnace is mentioned.
Next, although it is cured, it is preferable to irradiate an active energy ray as a curing method.
Examples of the active energy rays include ultraviolet rays and electron beams.

After coating and drying the composition for forming a low refractive index film, when the coating film is irradiated with active energy rays, it is contained in the perfluoro group-containing (meth) acrylate resin and the low refractive index hollow silica fine particles. A cured film in which (meth) acrylic acid ester groups are quickly crosslinked and polymerized into a three-dimensional network is formed. For this reason, the obtained cured film is strong and excellent in scratch resistance and the like, and further, the perfluoro group having a low surface energy is exposed on the surface thereof, and thus the chemical resistance is excellent.
EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Preparation of low refractive index film-forming composition (1) Perfluoro group-containing (meth) acrylic acid ester (resin) triacryloylheptadecafluorononenyl pentaerythritol (manufactured by Kyoeisha Chemical Co., Ltd .: trade name PE-3ARf) 50 parts by weight, the hollow fine particles by weight is 100%, whereas 3-methacryloxypropyl surface-treated with silane 20 wt% and ethyl orthosilicate 10 wt% (treated with a silane coupling agent) hollow silica 250 parts by weight (solid content concentration ) of a methyl isobutyl ketone (MIBK) dispersion of system fine particles (manufactured by Catalyst Chemical Industry Co., Ltd .: ELCOM KC-1001SIV, particle refractive index 1.30, Na ₂ O: 3 ppm, NH ₃ : 1000 ppm) 20 wt%), as a photopolymerization initiator 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one (Ciba Specialty Ke Karuzu Co.: trade names Irgacure 907) were mixed with 10 parts by weight of a low refractive index film-forming composition (1) was prepared.

"Observation of appearance of low refractive index film forming composition"
The appearance of the obtained composition for forming a low refractive index film (1) was observed by visual observation as to whether it was transparent, fluorescent, or cloudy, and the results are shown in Table 1.
"Refractive index measurement of low refractive index film forming composition"
The obtained refractive index film-forming composition (1) was measured for refractive index at 25 ° C. using an Appe refractometer (manufactured by Atago Co., Ltd.), and the results are shown in Table 1.

"Curability test of low refractive index film forming composition"
The obtained composition for forming a low refractive index film (1) was coated on a glass substrate so as to have a film thickness of 1 μm, and an ultraviolet irradiation device (manufactured by Nippon Battery Co., Ltd.) equipped with an 80 W high-pressure mercury lamp. A cured film was obtained by irradiating about 1 J / cm ² of ultraviolet rays. The cured film was evaluated by finger touch and the results are shown in Table 1. A hard and fully cured product was marked with ◯, and a tacky and insufficiently cured product was marked with ×.

Preparation of base material (1) with cured film 50 parts by weight of PET film (Toyobo: A4300, base material Haze: 0.8%) and dipentaerythritol hexaacrylate Kyoeisha Chemical Co., Ltd .: trade name DPE-6A) 2 parts by weight of 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one (product name: Irgacure 907, manufactured by Ciba Specialty Chemicals) and 2-propanol as a photopolymerization initiator 45 parts by weight are mixed, coated with a bar coater # 10, dried in a heat circulating furnace at 80 ° C. for 120 seconds, and then an ultraviolet irradiation device (manufactured by Nippon Batteries Co., Ltd.) equipped with an 80 W high-pressure mercury lamp. A hard coat film having a thickness of 5 μm was obtained by curing by irradiating with ultraviolet rays of about 400 mJ / cm ² . On top of that, the low refractive index film-forming composition (1) was applied with a bar coater so as to have a film thickness of 100 nm, dried in a thermal circulation furnace at 80 ° C. for 120 seconds, and then equipped with an 80 W high pressure mercury lamp. A cured film-coated substrate (1) was prepared by irradiating with an ultraviolet ray of about 1000 mJ / cm ^{2 with} an ultraviolet ray irradiating device (manufactured by Nihon Battery Co., Ltd.) and curing.

  The resulting cured film-coated substrate (1) was evaluated for transparency (total light transmittance, haze), refractive index, reflectance, scratch resistance test, and chemical resistance test. It is shown in Table 1.

"Measurement of refractive index of cured film"
A part of the cured film was peeled from the substrate from the substrate with cured film (1), and the refractive index of the cured film was measured at 25 ° C. using an appe refractometer.
"Measurement of reflectivity of cured film"
The back surface of the substrate with cured film (1) was coated with a matte black spray, and the reflectivity of the surface was measured using a reflectometer (MCPD-3000, manufactured by Otsuka Electronics Co., Ltd.) at 5 °.

"Measurement of total light transmittance and Haze of cured film"
The total light transmittance and haze of the substrate with cured film (1) were measured using a haze computer (manufactured by Nippon Denka Co., Ltd .: Model 300A).
"Abrasion resistance test of cured film"
The substrate with cured film (1) was rubbed 10 times with standard # 0000 steel wool applied with a load of 100 g / cm ² , and the degree of scratches on the film surface was visually observed.
The case where the degree of the occurrence of scratches was less than 10 was rated as ◯, the case where 10 to 20 scratches were indicated as Δ, and the case where the scratches were innumerable as X.

"Chemical resistance of cured film"
One drop of a 3 wt% sodium hydroxide aqueous solution was dropped on the substrate with a cured film (1) and allowed to stand at room temperature for 30 minutes, and then the appearance change of the cured film was visually observed.
The case where there was no change in appearance was marked with ◎, the case where there was almost no change in appearance, ○, the case where it was partially whitened or partially eroded, and the case where it was whitened or completely eroded.

Preparation of Low Refractive Index Film-Forming Composition (2) In Example 1, perfluorocyclohexanedimethanol diacrylate (Kyoeisha Chemical Co., Ltd.) instead of PE-3ARf as perfluoro group-containing (meth) acrylic acid ester (resin) ) Product: Trade name LINC-1001) A composition for forming a low refractive index film (2) was prepared in the same manner as in Example 1 except that 50 parts by weight were used.
The obtained composition for forming a low refractive index film (2) was subjected to appearance observation, refractive index measurement and curability test, and the results are shown in Table 1.

Preparation of substrate with cured film (2) A substrate with cured film (2) was prepared in the same manner as in Example 1 except that the composition for forming a low refractive index film (2) was applied.
The obtained cured film-coated substrate (2) was subjected to transparency evaluation, refractive index measurement, reflectance measurement, scratch resistance test, and chemical resistance test. The results are shown in Table 1.

Preparation of low refractive index film-forming composition (3) In Example 1, 30 parts by weight of PE-3Arf, 350 parts by weight of ELCOM KC-1001SIV, and 10 parts by weight of Irgacure 907 were used. A low refractive index film-forming composition (3) was prepared in the same manner as in Example 1 except for the above.
The obtained composition for forming a low refractive index film (3) was subjected to observation of appearance, measurement of refractive index and curability test, and the results are shown in Table 1.

Preparation of cured film-coated substrate (3) A cured film- coated substrate (3) was prepared in the same manner as in Example 1 except that the low refractive index film-forming composition (3) was applied.
The obtained cured film-coated substrate (3) was subjected to transparency evaluation, refractive index measurement, reflectance measurement, scratch resistance test, and chemical resistance test. The results are shown in Table 1.

Preparation of composition for forming low refractive index film (4) In Example 2, 30 parts by weight of LINC-1001, 134 parts by weight of ELCOM KC-1001SIV, and non-fluorine-containing polyfunctional (meth) acrylate (resin And 3 parts by weight of light acrylate DPE-6A (manufactured by Kyoeisha Chemical Co., Ltd.) and 10 parts by weight of Irgacure 907 were used in the same manner as in Example 2 for forming a low refractive index film. Composition (4) was prepared.
The resulting low refractive index film-forming composition (4) was subjected to appearance observation, refractive index measurement and curability test, and the results are shown in Table 1.

Preparation of substrate with cured film (4) A substrate with cured film (4) was prepared in the same manner as in Example 1 except that the composition (4) for forming a low refractive index film was applied.
The obtained cured film-coated substrate (4) was subjected to transparency evaluation, refractive index measurement, reflectance measurement, scratch resistance test, and chemical resistance test, and the results are shown in Table 1.

Preparation of low refractive index film-forming composition (5) Perfluoro group-containing (meth) acrylic acid ester (resin) triacryloylheptadecafluorononenyl pentaerythritol (manufactured by Kyoeisha Chemical Co., Ltd .: trade name PE-3ARf) Hollow silica fine particles (catalyst chemical industry Co., Ltd. ) treated with a surface treatment ( treated with a silane coupling agent) with 50 parts by weight and the weight of hollow fine particles as 100% and 30% by weight of heptadecatrifluorodecyltrimethoxysilane. ) Made: ELCOM KC-1002SIV, particle refractive index 1.30, Na ₂ O: 1.5 ppm, NH ₃ : 480 ppm) methyl isobutyl ketone (MIBK) dispersion 250 parts by weight (solid content concentration 20% by weight) , 2-Methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator Lugacure 907) A composition for forming a low refractive index film (5) was prepared in the same manner as in Example 1 except that 10 parts by weight were mixed.
The resulting low refractive index film-forming composition (5) was subjected to appearance observation, refractive index measurement and curability test, and the results are shown in Table 1.

Preparation of substrate with cured film (5) A substrate with cured film (5) was prepared in the same manner as in Example 1, except that the composition for forming a low refractive index film (5) was applied.
The obtained cured film-coated substrate (5) was subjected to transparency evaluation, refractive index measurement, reflectance measurement, scratch resistance test, and chemical resistance test, and the results are shown in Table 1.

Comparative Example 1

Preparation of low refractive index film-forming composition (R-1) Perfluoro group-containing (meth) acrylic acid ester (resin) triacryloylheptadecafluorononenyl pentaerythritol (manufactured by Kyoeisha Chemical Co., Ltd .: trade name PE- 3ARf) and 100 parts by weight of 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one (product name: Irgacure 907, manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator ) Was mixed with 10 parts by weight to prepare a low refractive index film-forming composition (R-1).
The resulting low refractive index film-forming composition (R-1) was subjected to appearance observation, refractive index measurement and curability test, and the results are shown in Table 1.

Preparation of substrate with cured film (R-1) A substrate with cured film (R-1) was prepared in the same manner as in Example 1 except that the composition for forming a low refractive index film (R-1) was applied. did.
The obtained cured film-coated substrate (R-1) was subjected to transparency evaluation, refractive index measurement, reflectance measurement, scratch resistance test, and chemical resistance test. The results are shown in Table 1.

Comparative Example 2

Preparation of low refractive index film-forming composition (R-2) Hollow silica-based fine particles treated with a silane coupling agent with a solid content concentration of 20% by weight (manufactured by Catalyst Chemical Industries, Ltd .: ELCOM KC-1001SIV, particle refractive index 1.30, Na ₂ O: 3 ppm, NH ₃ : 1000 ppm) methyl isobutyl ketone (MIBK) dispersion 100 parts by weight, and 2-methyl-1 [4- (methylthio) phenyl] -2- Morpholinopropan-1-one (manufactured by Ciba Specialty Chemicals: trade name Irgacure 907) was mixed with 2 parts by weight to prepare a composition (R-1) for forming a low refractive index film.
The resulting composition for forming a low refractive index film (R-2) was subjected to observation of appearance, measurement of refractive index and curability test, and the results are shown in Table 1.

Preparation of substrate with cured film (R-2) A substrate with cured film (R-2) was prepared in the same manner as in Example 1 except that the composition for forming a low refractive index film (R-2) was applied. did.
The obtained cured film-coated substrate (R-2) was subjected to transparency evaluation, refractive index measurement, reflectance measurement, scratch resistance test, and chemical resistance test, and the results are shown in Table 1.

As is clear from Table 1, the cured films of Examples 1 to 5 were excellent in curability, transparency, scratch resistance, and chemical resistance, and had a refractive index of 1.40 or less.
On the other hand, the cured film of Comparative Example 1 is excellent in curability, transparency, scratch resistance, and chemical resistance as in Examples 1 to 5, but has a relatively high refractive index of 1.45. became. Further, the cured film of Comparative Example 2 had a refractive index of 1.35 and was lower than Examples 1 to 5, but was low in chemical resistance and scratch resistance, and as a film for the outermost layer such as an antireflection film. Is not practical.

Claims (6)

Hollow silica-based fine particles treated with a perfluoro group-containing (meth) acrylic ester resin represented by the following chemical formula (II) or (III) and a silane coupling agent represented by the following formula (I) : Hollow silica-based fine particles in which the content of ammonia and / or ammonium ions in the hollow silica-based fine particles is 2500 ppm or less as NH ₃ and the content of alkali is ₃ ppm or less as M _A2 O (M _A : alkali metal element) A composition for forming a low refractive index film comprising 10% to 90% by weight of the perfluoro group-containing (meth) acrylic ester resin as a solid content in the cured film obtained from the composition, and the silane cup A composition for forming a low refractive index film , comprising 90 to 10% by weight of a hollow silica fine particle surface-treated with a ring agent as a solid content .
R _n SiX _(4-n)・ ・ ・ ・ ・ ・ （I）
(However, R: C1-C4 alkoxy group, methacryloyloxy group, acryloyloxy group, perfluoro (meth) acryloyl group, X: C1-C4 alkoxy group, silanol group, halogen or hydrogen)
_{(C p F q -O) r} -A - (- O-CO-CR = CH 2) S ······ (II)
(In the formula (II), p is 1 to 18, q is 3 to 37, r + s is 3 to 20, r is 1 to 18, s is an integer of 2 to 19, and -A- is the dehydroxylation residue of the polyhydric alcohol. Group R represents a hydrogen atom or a methyl group.)
(R ^1- ) _x- (C _l H _m F _n )-{(CH ₂ ) _y -O-CO-C (-R ² ) = CH ₂ } _z (III)
(In the formula (III),-(C _l H _m F _n )-is an alicyclic group in which l is 3 to 10, m is 0 to 4, and n is 2 to 18, x is 0 to 8, and y is (0 to 4, z is 2 to 6, R ¹ -represents a linear or branched alkyl group or fluoroalkyl group having 1 to 10 carbon atoms, and -R ² represents a hydrogen atom or a methyl group.)
Furthermore, the non-fluorine-containing polyfunctional (meth) acrylic ester resin is used in an amount of 1 to 50 with respect to the total amount of the perfluoro group-containing (meth) acrylic ester resin and the non-fluorine-containing polyfunctional (meth) acrylic ester resin. low refractive index film-forming composition of claim 1 Symbol mounting, characterized in that it comprises by weight%. The hollow average particle size of the silica-based particles is in the range of 5 to 500 nm, a low refractive according to claim 1 or 2 refractive index lies in the range of 1.15 to 1.40 Composition for forming a rate film. The hollow silica fine particles are composed of silica and an inorganic oxide other than silica, and the molar ratio MO _X / SiO ₂ is 0.0001 when the silica is expressed by SiO ₂ and the inorganic oxide other than silica is expressed by MO _X. It is in the range of -0.2, The composition for low refractive index film formation in any one of Claims 1-3 characterized by the above-mentioned. A base material with a cured film, which is formed on the surface of the base material alone or together with other coatings, using the composition for forming a low refractive index film according to any one of claims 1 to 4 . The base material with a cured film according to claim 5 , wherein the refractive index of the cured film is in a range of 1.20 to 1.40, and a film thickness is in a range of 0.01 to 10 μm.