JP2016136228A - Anti-reflection film, polarizing plate, cover glass, image display device, and manufacturing method for anti-reflection film - Google Patents

Abstract

Disclosed is an antireflection film having a moth-eye structure on the surface, which has high durability against pressure in the thickness direction of the moth-eye structure, low reflectance, and low haze. Another object of the present invention is to provide a polarizing plate including an antireflection film, a cover glass, an image display device, and a method for producing the antireflection film.
An antireflection film comprising a base material, and an antireflection layer containing a binder resin and metal oxide particles having an average primary particle size of 50 nm or more and 250 nm or less,
The surface of the metal oxide particles has a hydroxyl group amount of 1.00 × 10 ⁻¹ or less,
The indentation hardness of the metal oxide particles is 400 MPa or more,
The binder resin is a resin having a hydroxyl group,
The antireflection layer has a moth-eye structure having a concavo-convex shape formed of metal oxide particles on the surface opposite to the substrate side interface, an antireflection film, a polarizing plate including the antireflection film, a cover glass, and an image Display device and method for producing antireflection film.
[Selection figure] None

Description

  The present invention relates to an antireflection film, a polarizing plate, a cover glass, an image display device, and a method for producing an antireflection film.

In image display devices such as cathode ray tube display (CRT), plasma display (PDP), electroluminescence display (ELD), fluorescent display (VFD), field emission display (FED), and liquid crystal display (LCD), An antireflection film may be provided in order to prevent a decrease in contrast and reflection of an image due to reflection of external light on the display surface. In addition to the image display device, an antireflection function may be provided by an antireflection film.

  As an antireflection film, an antireflection film having a fine uneven shape with a period equal to or less than the wavelength of visible light on the surface of the substrate, that is, an antireflection film having a so-called moth eye structure is known. With the moth-eye structure, it is possible to create a refractive index gradient layer in which the refractive index continuously changes from air to the bulk material inside the substrate, thereby preventing light reflection.

  As an antireflection film having a moth-eye structure, Patent Document 1 discloses that a coating liquid containing a transparent resin monomer and fine particles is applied on a transparent substrate and cured to form a transparent resin in which the fine particles are dispersed. An antireflection film having an uneven structure manufactured by etching a resin is described.

JP 2009-139796 A

However, it has been found that the antireflection film described in Patent Document 1 causes a problem that the antireflection function is lost when the moth-eye structure formed of particles is subjected to a high pressure in the thickness direction and the particles are crushed. It was.
The present inventors examined this problem, and used metal oxide particles having a high indentation hardness and a small amount of hydroxyl groups on the surface as particles forming a moth-eye structure. As a result, durability against pressure in the thickness direction was improved. However, the dispersibility of the particles in the binder resin used for the antireflection layer is lowered, the particles are aggregated in the binder resin, and the haze of the antireflection layer is increased or the reflectance is increased. Problem has occurred.

  In view of the above, an object of the present invention is to provide an antireflection film having a moth-eye structure on the surface, which has high durability against pressure in the thickness direction of the moth-eye structure, low reflectance, and low haze. Is to provide. Another object of the present invention is to provide a polarizing plate, a cover glass, an image display device, and a method for producing the antireflection film including the antireflection film.

As a result of intensive studies, the present inventors have used metal oxide particles having a high indentation hardness and a small amount of hydroxyl groups on the surface as particles forming the moth-eye structure, and having a hydroxyl group as a binder resin for the antireflection layer. It has been found that the above problems can be solved by using a resin.
That is, the present invention has the following configuration.

[1]
An antireflection film comprising a base material, an antireflection layer containing a binder resin and metal oxide particles having an average primary particle size of 50 nm to 250 nm,
The surface of the metal oxide particles has a hydroxyl group amount of 1.00 × 10 ⁻¹ or less,
The indentation hardness of the metal oxide particles is 400 MPa or more,
The binder resin is a resin having a hydroxyl group,
The antireflection layer is an antireflection film having a moth-eye structure having a concavo-convex shape formed of the metal oxide particles on a surface opposite to the interface on the substrate side.
[2]
The concave-convex shape of the antireflection layer is such that B / A, which is a ratio of the distance A between the apexes of adjacent convex portions and the distance B between the centers of the adjacent convex portions and the concave portions, is 0.5 or more. The antireflection film according to [1].
[3]
The antireflection film according to [1] or [2], which contains only metal oxide particles having a primary particle size of 50 nm or more and 250 nm or less as the metal oxide particles.
[4]
The antireflection film according to any one of [1] to [3], wherein the metal oxide particles are silica particles.
[5]
The antireflection film according to any one of [1] to [4], wherein the metal oxide particles are calcined silica particles.
[6]
The antireflection film according to any one of [1] to [5], wherein the metal oxide particles are calcined silica particles whose surface is modified with a compound having a (meth) acryloyl group.
[7]
The antireflection film according to [2], wherein the half width of the distribution of the distance A is 200 nm or less.
[8]
The binder resin is a resin obtained by polymerizing a polymerizable compound having at least one of a group having an ethylenically unsaturated double bond and an epoxy group as a polymerizable group [1] to [7] 2. The antireflection film according to item 1.
[9]
The antireflection film as described in [8], wherein one molecule of the polymerizable compound has a hydroxyl group equivalent of 1 to 10,000.
[10]
The antireflection film according to any one of [1] to [9], which has a hard coat layer between the substrate and the antireflection layer.
[11]
A polarizing plate having a polarizer and at least one protective film for protecting the polarizer, wherein at least one of the protective films is the antireflection film according to any one of [1] to [10]. A polarizing plate.
[12]
A cover glass having the antireflection film according to any one of [1] to [10] as a protective film.
[13]
The image display apparatus which has an antireflection film of any one of [1]-[10], or a polarizing plate of [11].
[14]
A method for producing an antireflection film comprising a base material, and an antireflection layer containing a binder resin and metal oxide particles having an average primary particle size of 50 nm to 250 nm,
The surface of the metal oxide particles has a hydroxyl group amount of 1.00 × 10 ⁻¹ or less,
The indentation hardness of the metal oxide particles is 400 MPa or more,
The binder resin is a resin having a hydroxyl group,
The antireflection layer has a moth-eye structure having an uneven shape formed by the metal oxide particles on the surface opposite to the interface on the base material side,
An antireflection layer-forming composition containing a polymerizable compound for forming a binder resin having a polymerizable functional group and metal oxide particles having an average primary particle size of 50 nm to 250 nm is applied on the base material. The manufacturing method of the antireflection film which has a process.
[15]
[1], [2], [2] including both metal oxide fine particles having an average primary particle size of 120 nm to 250 nm and metal oxide particles having an average primary particle size of 50 nm to less than 120 nm as the metal oxide particles. The antireflection film according to any one of 4] to [10].
[16]
The antireflection film according to [15], wherein the metal oxide particles having an average primary particle diameter of 50 nm or more and less than 120 nm have a hydroxyl group amount of 1.00 × 10 ⁻¹ or less and an indentation hardness of 400 MPa or more.
[17]
The metal oxide particles having an average primary particle size of 50 nm or more and less than 120 nm have an amount of hydroxyl groups of more than 1.00 × 10 ⁻¹ or an indentation hardness of less than 400 MPa [15].
[18]
[15] to [17] containing the metal oxide particles having an average primary particle size of not less than 120 nm and not more than 250 nm in a frequency of 2 to 5 times the metal oxide particles having an average primary particle size of not less than 50 nm and less than 120 nm. The antireflection film according to any one of the above.

  According to the present invention, it is possible to provide an antireflection film having a moth-eye structure on the surface, having high durability against pressure in the thickness direction of the moth-eye structure, low reflectance, and low haze. it can. Moreover, according to this invention, the polarizing plate containing this antireflection film, a cover glass, an image display apparatus, and the manufacturing method of an antireflection film can be provided.

It is a cross-sectional schematic diagram which shows an example of the antireflection film of this invention.

[Antireflection film]
The antireflection film of the present invention is
An antireflection film comprising a base material, an antireflection layer containing a binder resin and metal oxide particles having an average primary particle size of 50 nm to 250 nm,
The surface of the metal oxide particles has a hydroxyl group amount of 1.00 × 10 ⁻¹ or less,
The indentation hardness of the metal oxide particles is 400 MPa or more,
The binder resin is a resin having a hydroxyl group,
The antireflection layer is an antireflection film having a moth-eye structure having a concavo-convex shape formed of metal oxide particles on the surface opposite to the interface on the substrate side.

  Hereinafter, the antireflection film of the present invention will be described in detail.

An example of a preferred embodiment of the antireflection film of the present invention is shown in FIG.
The antireflection film 10 in FIG. 1 has a base material 1 and an antireflection layer 2. The antireflection layer 2 has a moth-eye structure having a concavo-convex shape formed by metal oxide particles 3 on the surface opposite to the substrate 1.
The antireflection layer 2 includes metal oxide particles 3 and a binder resin 4.

(Moth eye structure)
The surface of the antireflection layer opposite to the base material has a moth-eye structure having a concavo-convex shape formed by metal oxide particles.
Here, the moth-eye structure refers to a processed surface of a substance (material) for suppressing light reflection, and a structure having a periodic fine structure pattern. In particular, for the purpose of suppressing the reflection of visible light, it refers to a structure having a fine structure pattern with a period of less than 780 nm. It is preferable that the period of the fine structure pattern is less than 380 nm because the color of the reflected light is eliminated. A period of 100 nm or more is preferable because light with a wavelength of 380 nm can recognize a fine structure pattern and is excellent in antireflection properties. The presence or absence of the moth-eye structure can be confirmed by observing the surface shape with a scanning electron microscope (SEM), an atomic force microscope (AFM), or the like, and examining whether the fine structure pattern is formed.

The concavo-convex shape of the antireflection layer of the antireflection film of the present invention is B / A, which is a ratio of the distance A between the apexes of adjacent convex portions and the distance B between the center and the concave portion between the apexes of adjacent convex portions. Is preferably 0.5 or more. When B / A is 0.5 or more, the depth of the concave portion increases with respect to the distance between the convex portions, and a refractive index gradient layer in which the refractive index changes more gradually from the air to the inside of the antireflection layer is formed. Therefore, the reflectance can be further reduced.
B / A can be controlled by the volume ratio of the binder resin and the metal oxide particles in the antireflection layer after curing. Therefore, it is important to appropriately design the blending ratio between the binder resin and the metal oxide particles. Further, the volume ratio of the binder resin and the metal oxide particles in the antireflection layer is increased in the composition for forming the antireflection layer by allowing the binder resin to permeate the substrate or volatilize in the process of producing the moth-eye structure. Therefore, it is also important to set the matching with the base material appropriately.
Furthermore, in order to make B / A 0.5 or more and reduce the reflectance, it is preferable that the metal oxide particles forming the convex portions are uniformly spread with a high filling rate. In addition, it is important that the filling rate is not too high. If the filling rate is too high, adjacent particles come into contact with each other and the B / A of the concavo-convex structure is reduced. From the above viewpoint, it is preferable that the content of the metal oxide particles forming the convex portion is adjusted so as to be uniform throughout the antireflection layer. The filling rate can be measured as the area occupancy of the particles located on the most surface side when observing the metal oxide particles forming the convex portions from the surface by SEM or the like, and is preferably 30% to 95%, -90% is more preferable, and 50-85% is still more preferable.
When particles with a small amount of hydroxyl groups on the surface, such as baked silica particles, are used as the metal oxide particles, the dispersibility of the particles in the binder resin when a resin having no hydroxyl groups is used as the binder resin for the antireflection layer. It can be presumed that the phenomenon in which the particles are aggregated in the binder resin and the reflectance is increased due to the decrease in B / A due to the contact between adjacent particles. At this time, B / A can be increased by using the resin having a hydroxyl group in the present invention as the binder resin.

A method for measuring B / A, which is a ratio of the distance A between the apexes of adjacent convex portions and the distance B between the center between the apexes of adjacent convex portions and the concave portion, will be described in more detail below.
B / A can be measured by cross-sectional SEM observation of the antireflection film. The antireflection film sample is cut with a microtome to obtain a cross section, and SEM observation is performed at an appropriate magnification (about 5000 times). For easy observation, the sample may be subjected to appropriate processing such as carbon deposition and etching. B / A is the distance between the vertices of adjacent protrusions at the interface between the air and the sample, and the vertices of adjacent protrusions in the plane perpendicular to the substrate surface including the vertices of the adjacent protrusions. The distance between the straight line connecting the two and the vertical bisector reaching the particle or the binder resin is B, and when 100 points are measured, the average value of B / A is calculated.
In the SEM photograph, there are cases where the distance A between the vertices of the adjacent convex portions and the distance B between the vertices of the adjacent convex portions and the concave portion B cannot be measured accurately with respect to all the projected and recessed portions. However, in that case, the length may be measured by paying attention to the convex portion and the concave portion shown on the near side in the SEM image.
Note that the concave portion needs to be measured at the same depth as the particles forming the two adjacent convex portions to be measured in the SEM image. This is because if the distance to a particle or the like reflected on the near side is measured as B, B may be estimated small.

  B / A is preferably 0.5 or more, more preferably 0.6 or more, and still more preferably 0.7 or more. Moreover, from the viewpoint that the moth-eye structure can be firmly fixed and has excellent scratch resistance, it is preferably 0.9 or less.

In order to reduce the reflectance, it is preferable that the metal oxide particles are uniformly spread with a high filling rate. It is also important that the filling rate is not too high. If the filling rate is too high, adjacent particles come into contact with each other to reduce the uneven B / A, resulting in an increase in reflectance.
From the above viewpoint, the content of the metal oxide particles is preferably adjusted to be uniform throughout the antireflection layer. The filling factor can be measured as the area occupancy of the particles located on the most surface side when the metal oxide particles are observed from the surface by SEM or the like. The filling rate is preferably 30% to 95%, more preferably 40 to 90%, and still more preferably 50 to 85%.

(Metal oxide particles)
The metal oxide particles forming the moth-eye structure of the antireflection layer will be described.
The metal oxide particles have an average primary particle size of 50 nm or more and 250 nm or less, a surface hydroxyl group amount of 1.00 × 10 ⁻¹ or less, and an indentation hardness of 400 MPa or more.

As the metal oxide particles, metal oxide particles having an average primary particle size of 50 nm or more and 250 nm or less and a dispersion degree Cv value of the average primary particle size of 10% or less can be preferably used. Dispersity Cv value is Cv value = ([standard deviation of average primary particle size] / [average average particle size]) × 100
(1) is a value (unit:%) that can be obtained by calculation, and the smaller the value, the greater the average primary particle size. The average primary particle size is measured using a scanning electron microscope (SEM). The average particle diameter of the metal oxide particles and the standard deviation thereof are calculated based on the measured values of the particle diameters of 200 or more metal oxide particles. In addition, the average particle diameter here means the maximum diameter of a circumscribed circle when the particles are not spherical. Also in the case of a mixture of a plurality of types of particles having different average primary particle sizes, the Cv value as a whole particle is calculated.
When the average primary particle size is 50 nm or more, it can function as an antireflection layer having a moth-eye structure, and when it is 250 nm or less, Bragg diffraction due to regular arrangement of metal oxide particles hardly occurs in the visible light region. The color development (coloring) phenomenon derived from this is not shown. Therefore, it is preferable that the Cv value is small because particle aggregation is less likely to occur and an antireflection layer having a low reflectance and a high transmittance can be formed without coloring. The average primary particle size is preferably from 100 nm to 220 nm, and more preferably from 120 nm to 200 nm. The Cv value is preferably 1 to 10%, more preferably 1 to 5%.
For the reason that the Cv value can be reduced, the metal oxide particles preferably contain only metal oxide particles having a primary particle size of 50 nm or more and 250 nm or less, and the primary particle size is 100 n.
It is more preferable to contain only metal oxide particles of m to 220 nm, and it is more preferable to contain only metal oxide particles having a primary particle size of 120 nm to 200 nm.

In another aspect, the metal oxide fine particles preferably include both metal oxide fine particles having an average primary particle size of 120 nm or more and 250 nm or less and metal oxide particles having an average primary particle size of 50 nm or more and less than 120 nm. In this case, particles having a larger particle size mainly contribute to the moth-eye structure, and particles having a smaller particle size are mixed between the large particles, thereby suppressing aggregation of the large particles. As a result, B / A May be increased, and the reflectance and haze may be improved.
Since metal oxide particles having a primary particle size of 50 nm or more and less than 120 nm are more immersed in the binder, the convex portion as the antireflection layer is formed by metal oxide fine particles having a primary particle size of 120 nm or more and 200 nm or less. Point to.
The frequency of metal oxide particles having an average primary particle size of 50 nm or more and less than 120 nm with respect to metal oxide fine particles having an average primary particle size of 120 nm or more and 250 nm or less is preferably 2 to 5 times as high. By setting this range, the aggregation suppressing effect is high and the reflectance can be lowered. The metal oxide particles having an average primary particle size of 50 nm or more are preferably an average primary particle size of 75 nm or more and 110 nm or less because the reflectance can be particularly lowered.
When metal oxide particles having different average primary particle sizes are used in combination, it is preferable to make the hydroxyl group amounts on the surfaces of both particles close to each other because aggregation is less likely.
However, since the metal oxide particles having an average primary particle size of 50 nm or more and less than 120 nm are mainly used for inhibiting the aggregation of metal oxide particles having an average primary particle size of 120 nm or more and 250 nm or less and separating them, they are available. Metal oxide particles having an easy hydroxyl group amount of more than 1.00 × 10 ⁻¹ or an indentation hardness of less than 400 MPa may be used.

  The average primary particle size of the metal oxide particles refers to the 50% cumulative particle size of the volume average particle size. When measuring the average primary particle diameter of the metal oxide particles contained in the antireflection layer, it can be measured by an electron micrograph. For example, the antireflection film is observed from the surface side by SEM observation at an appropriate magnification (about 5000 times), the diameter of each of the 100 primary particles is measured, the volume is calculated, and the cumulative 50% particle size is calculated. The average primary particle size can be obtained. When the particles are not spherical, the average value of the major and minor diameters is regarded as the diameter of the primary particles. At this time, for easy observation, the sample may be appropriately subjected to carbon deposition, etching, or the like.

In the present invention, the amount of hydroxyl groups on the particle surface is defined as follows. The amount of hydroxyl groups is measured by solid ²⁹ Si NMR ( ²⁹ Si CP / MAS). Although the metal element M on the surface of the metal oxide fine particle is bonded to n hydroxyl groups, and the signal intensity is defined as Qn, the amount of hydroxyl groups on the particle surface is as follows: Qn × n ÷ (particle radius (unit: nm :) squared). For example, when the particle is silica (with a particle radius R), silicon bonded to 4 neutral oxygen atoms (signal intensity Q0), silicon bonded to 3 neutral oxygen atoms and one hydroxyl group (signal intensity Q1) , there silicon bonded to two neutral oxygen 2 atoms and hydroxyl groups (signal intensity Q2) is, the particle surface hydroxyl group content is (Q1 × 1 + Q2 × 2 ) ÷ R 2. In the case of silica, the signal giving signal intensity Q2 has a chemical shift of −91 to −94 ppm, the signal giving signal intensity Q1 has a chemical shift of −100 to −102 ppm, and the signal giving signal intensity Q0 has a chemical shift of −109 to −111 ppm.

The amount of hydroxyl groups on the particle surface becomes smaller as it becomes harder by firing, preferably 1.00 × 10 ^{−5 to} 1.00 × 10 ^−1, more preferably 1.00 × 10 ^{−4 to} 5.00 × 10 ^−2. 5.00 × 10 ^{−4 to} 1.00 × 10 ⁻³ is more preferable.

The indentation hardness of the metal oxide particles is 400 MPa or more, preferably 450 MPa or more, and more preferably 550 MPa or more. The indentation hardness of the metal oxide particles is preferably 400 MPa or more because durability against pressure in the thickness direction of the moth-eye structure is increased. Further, the indentation hardness of the metal oxide particles is preferably 1000 MPa or less so as not to be brittle and easily broken.
The indentation hardness of the metal oxide particles can be measured with a nanoindenter or the like. As a specific measuring method, a sample can be measured by arranging metal oxide particles on a substrate (glass plate, quartz plate, etc.) harder than itself so that they do not overlap one or more steps and pressing them with a diamond indenter. At this time, it is preferable to fix with a resin or the like so that the particles do not move. However, when fixing with resin, it adjusts so that a part of particle | grain may be exposed. Moreover, it is preferable to specify a pushing position with a tribo indenter.
Also in the present invention, particles are arranged on a substrate, a sample in which particles are bound and fixed using a small amount of curable resin so as not to affect the measurement value, and the sample is measured by an indenter. Was used to determine the indentation hardness of the metal oxide particles.

  Examples of the metal oxide particles include silica particles, titania particles, zirconia particles, and antimony pentoxide particles. From the viewpoint that moth-eye structures are easily formed because haze is hardly generated because the refractive index is close to that of many binders. Silica particles are preferred.

The metal oxide particles are particularly preferably calcined silica particles because of the reasonably high amount of hydroxyl groups on the surface and hard particles.
The calcined silica particles are manufactured by a known technique in which silica particles are obtained by hydrolyzing and condensing a hydrolyzable silicon compound in an organic solvent containing water and a catalyst, and then the silica particles are calcined. For example, JP2003-176121A, JP2008-137854A, and the like can be referred to.
Although it does not specifically limit as a raw material silicon compound which manufactures a burning silica particle, Chlorosilanes, such as tetrachlorosilane, methyltrichlorosilane, phenyltrichlorosilane, dimethyldichlorosilane, diphenyldichlorosilane, methylvinyldichlorosilane, trimethylchlorosilane, methyldiphenylchlorosilane Compounds: tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, methyltriethoxysilane, trimethoxyvinylsilane, triethoxyvinylsilane, 3-glycidoxypropyltrimethoxysilane, 3-chloro Propyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3- (2-aminoethylamino) propyltrimethoxy Silane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-chloropropylmethyldimethoxysilane, Alkoxysilane compounds such as diphenyldimethoxysilane, diphenyldiethoxysilane, dimethoxydiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane; tetraacetoxysilane, methyltriacetoxysilane, phenyltriacetoxysilane, dimethyldiacetoxysilane, diphenyldiacetoxysilane Acyloxysilane compounds such as trimethylacetoxysilane; dimethylsilanediol, diphenylsilanediol, tri Silanol compounds such as chill silanol; and the like. Of the above-exemplified silane compounds, the alkoxysilane compound is particularly preferred because it is more easily available and the resulting fired silica particles do not contain halogen atoms as impurities. As a preferred form of the calcined silica particles according to the present invention, it is preferred that the halogen atom content is substantially 0% and no halogen atoms are detected.
Although a calcination temperature is not specifically limited, 800-1300 degreeC is preferable and 1000 degreeC-1200 degreeC is more preferable.

The calcined silica particles are preferably calcined silica particles whose surface is modified with a compound having a (meth) acryloyl group. By using calcined silica particles whose surface is modified with a compound having a (meth) acryloyl group, effects such as improvement in dispersibility in the composition for forming an antireflection layer, improvement in film strength, and prevention of aggregation can be expected. . For specific examples of the surface treatment method and preferred examples thereof, reference can be made to the descriptions in [0119] to [0147] of JP-A-2007-298974.

  The shape of the metal oxide particles is most preferably spherical, but there is no problem even if the shape is not spherical such as indefinite.

  The metal oxide particles may be used by firing commercially available particles. As specific examples, IPA-ST-L (average primary particle size 50 nm, silica sol manufactured by Nissan Chemical Industries, Ltd.), IPA-ST-ZL (average primary particle size 80 nm, silica sol manufactured by Nissan Chemical Industries, Ltd.) , Snowtex MP-1040 (average primary particle size 100 nm, silica manufactured by Nissan Chemical Industries, Ltd.), Snowtex MP-2040 (average primary particle size 200 nm, silica manufactured by Nissan Chemical Industries, Ltd.), Seahoster KE-P10 ( Average primary particle size 150 nm, Nippon Shokubai Co., Ltd. amorphous silica), Seahoster KE-P20 (average primary particle size 200 nm, Nippon Shokubai Co., Ltd. amorphous silica), ASFP-20 (average primary particle size 200 nm, Nippon Electrochemical) (Alumina manufactured by Kogyo Co., Ltd.) and the like can be preferably used. Furthermore, as long as the requirements of the metal oxide particles of the present invention are satisfied, commercially available particles may be used as they are.

  The content ratio of the metal oxide particles and the binder resin is preferably 10/90 or more and 95/5 or less, more preferably 20/80 or more and 90/10 or less, (mass of metal oxide particles / binder resin mass), 30 / 70 to 85/15 is more preferable. It is preferable that (the mass of the metal oxide particles / the mass of the binder resin) is 10/90 or more because B / A of the concavo-convex shape of the moth-eye structure increases and the reflectance decreases. If the mass of the metal oxide particles / the mass of the binder resin is 95/5 or less, the adhesion between the metal oxide particles and the substrate is increased, or the metal oxide particles are less likely to aggregate during the manufacturing process, resulting in failure. Or haze deterioration is preferable.

  The distribution of the distance A between the vertices of adjacent convex portions in the antireflection layer is preferably 200 nm or less. When the distribution of A is 200 nm or less, the distribution of the distance between particles is narrow (sharp), which means that the particles are present uniformly without approaching or extremely separated from each other. It is preferable from the viewpoint of a decrease in reflectance. The half width of the A distribution is more preferably 125 nm or less, and further preferably 100 nm or less.

(Binder resin)
The binder resin for the antireflection layer will be described.
The binder resin of the antireflection layer is a resin having a hydroxyl group. Since the binder resin of the antireflection layer is a resin having a hydroxyl group, the dispersibility is high even in the above-described metal oxide particles having a surface hydroxyl group amount of 1.00 × 10 ⁻¹ or less. Thus, the metal oxide particles do not aggregate, the haze of the antireflection layer can be lowered, and the reflectance can also be lowered.

The binder resin is preferably a resin obtained by polymerizing a polymerizable compound having at least one of a group having an ethylenically unsaturated double bond and an epoxy group, and the ethylenically unsaturated double bond as a polymerizable group It is preferable that it is resin obtained by superposing | polymerizing the polymeric compound which has only the group which has this.
1-10000 are preferable, as for the hydroxyl group equivalent of 1 molecule of polymeric compounds, 100-5000 are more preferable, and 200-3000 are more preferable. In the present invention, the hydroxyl group equivalent is a molecular weight per hydroxyl group, and is a value obtained by dividing the molecular weight of the polymerizable compound by the number of hydroxyl groups contained in one molecule.
Examples of the polymerizable compound having a group having an ethylenically unsaturated double bond include a compound having a (meth) acryloyl group, a vinyl group, a styryl group, or an allyl group.
A compound having a (meth) acryloyl group and —C (O) OCH═CH ₂ is preferred, and a compound having a (meth) acryloyl group is more preferred.

  Specific examples of the polymerizable compound include (meth) acrylic acid diesters of alkylene glycol, (meth) acrylic acid diesters of polyoxyalkylene glycol, (meth) acrylic acid diesters of alcohol, ethylene oxide or propylene oxide adducts. Examples include (meth) acrylic acid diesters, epoxy (meth) acrylates, urethane (meth) acrylates, and polyester (meth) acrylates.

  Among these, esters of alcohol and (meth) acrylic acid are preferable (for example, 2-hydroxyethyl methacrylate), and esters of (poly) alcohol and (meth) acrylic acid are particularly preferable. For example, 2-hydroxyethyl acrylate (2-hydroxyethyl methacrylate) (hydroxyl group equivalent: 116), pentaerythritol triacrylate (hydroxyl group equivalent: 538), dipentaerythritol tetraacrylate (hydroxyl group equivalent: 228), dipenta Erythritol pentaacrylate (hydroxyl group equivalent: 524), 2-hydroxyethyl methacrylate (2-hydroxyethyl methacrylate) (hydroxyl group equivalent: 130), pentaerythritol trimethacrylate (hydroxyl group equivalent: 340), dipentaerythritol tetramethacrylate ( Hydroxyl group equivalent: 256), dipentaerythritol pentamethacrylate (hydroxyl group equivalent: 594) and the like.

  A commercially available compound can also be used as the polymerizable compound. Specifically, for example, NK ester 701A (manufactured by Shin-Nakamura Chemical Co., Ltd.) (hydroxyl group equivalent: 200), NK ester ACB-21 (manufactured by Shin-Nakamura Chemical Co., Ltd.) (hydroxyl group equivalent: 292) , KAYARAD PET30 (manufactured by Nippon Kayaku Co., Ltd.) (hydroxyl group equivalent: 533), NK ester A-TMM3 (manufactured by Shin-Nakamura Chemical Co., Ltd.) (hydroxyl group equivalent: 897), KAYARAD DPHA (Nippon Kayaku) (Manufactured by Co., Ltd.) (hydroxyl group equivalent: 1102), Aronix M-402 (manufactured by Toa Gosei Co., Ltd.) (hydroxyl group equivalent: 1597), Aronix M-405 (manufactured by Toa Gosei Co., Ltd.) (hydroxyl) Group equivalent: 3799), Aronix M-450 (manufactured by Toagosei Co., Ltd.) (hydroxyl group equivalent: 6986), and the like.

  A polymerizable compound may be used by mixing a plurality of compounds. At this time, the molecular weight is an average molecular weight depending on the blending ratio of the polymerizable compound, and the hydroxyl group equivalent is also a value obtained by dividing this by the average number of hydroxyl groups per molecule.

(Base material)
The base material in the antireflection film of the present invention is not particularly limited as long as it is a base material having translucency generally used as the base material of the antireflection film, but a plastic base material and a glass base material are preferable.
Various plastic substrates can be used, such as cellulose resin; cellulose acylate (triacetate cellulose, diacetyl cellulose, acetate butyrate cellulose), polyester resin; polyethylene terephthalate, (meth) acrylic resin, polyurethane, etc. Base materials containing polycarbonate resins, polycarbonates, polystyrenes, olefin resins, etc., preferably cellulose acylates, polyethylene terephthalates, or substrates containing (meth) acrylic resins, and substrates containing cellulose acylates Is more preferable. As the cellulose acylate, the base material described in JP 2012-093723 A can be preferably used.
The thickness of the plastic substrate is usually about 10 μm to 1000 μm, but it is 20 μm to 200 μm from the viewpoint of good handleability, high translucency, and sufficient strength.
m is preferable, and 25 μm to 100 μm is more preferable. As a light-transmitting property of the plastic substrate, a material having a visible light transmittance of 90% or more is preferable.

(Other functional layers)
The antireflection film of the present invention may have a functional layer other than the antireflection layer.
For example, the aspect which has a hard-coat layer between a base material and an antireflection layer is mentioned preferably. Further, an easy adhesion layer for imparting adhesion, a layer for imparting antistatic properties, or the like may be provided, or a plurality of these may be provided.

[Method for producing antireflection film]
Although the manufacturing method of the antireflection film of the present invention is not particularly limited, a manufacturing method using a coating method is preferable from the viewpoint of production efficiency.
That is, the manufacturing method of the antireflection film is:
A method for producing an antireflection film comprising a base material, and an antireflection layer containing a binder resin and metal oxide particles having an average primary particle size of 50 nm to 250 nm,
The surface of the metal oxide particles has a hydroxyl group amount of 1.00 × 10 ⁻¹ or less,
The indentation hardness of the metal oxide particles is 400 MPa or more,
The binder resin is a resin having a hydroxyl group,
The antireflection layer has a moth-eye structure composed of irregularities formed of metal oxide particles on the surface opposite to the substrate side interface,
A step of applying a composition for forming an antireflection layer containing a polymerizable compound for forming a binder resin having a polymerizable functional group and metal oxide particles having an average primary particle size of 50 nm to 250 nm on a substrate. It is a manufacturing method of the antireflection film which has.

The polymerizable compound for forming a binder resin having a polymerizable functional group and the metal oxide particles having an average primary particle size of 50 nm or more and 250 nm or less contained in the composition for forming an antireflection layer are the same as those described above.
The composition for forming an antireflection layer may contain a solvent, a polymerization initiator, a particle dispersing agent, a leveling agent, an antifouling agent and the like.
A solvent having a polarity close to that of the fine particles is preferably selected from the viewpoint of improving dispersibility. Specifically, for example, when the fine particles are metal oxide particles, an alcohol solvent is preferable, and examples thereof include methanol, ethanol, 2-propanol, 1-propanol, and butanol. For example, when the fine particles are metal resin particles or resin particles having a hydrophobic surface modified, ketone-based, ester-based, carbonate-based, alkane, aromatic-based solvents are preferable, and methyl ethyl ketone (MEK), dimethyl carbonate , Methyl acetate, acetone, methylene chloride, cyclohexanone and the like. These solvents may be used in a mixture of a plurality of types as long as the dispersibility is not significantly deteriorated.
The particle dispersing agent can facilitate uniform arrangement of the particles by reducing the cohesive force between the particles. The dispersant is not particularly limited, but is preferably an anionic compound such as a sulfate or phosphate, a cationic compound such as an aliphatic amine salt or a quaternary ammonium salt, a nonionic compound or a polymer compound. And a steric repulsion group are more preferred because they have a high degree of freedom in selection. A commercial item can also be used as a dispersing agent. For example, BYK Japan made of (stock) DISPERBYK160, DISPERBYK161, DISPERBYK162, DISPERBYK163, DISPERBYK164, DISPERBYK166, DISPERBYK167, DISPERBYK171, DISPERBYK180, DISPERBYK182, DISPERBYK2000, DISPERBYK2001, DISPERBYK2164, Bykumen, BYK-2009, BYK-P104, BYK-P104S, BYK-220S, Anti-Terra 203, Anti-Terra 204, Anti-Terra 205 (above product names) and the like can be mentioned.
By reducing the surface tension of the coating solution, the leveling agent can stabilize the solution after coating and facilitate the uniform arrangement of particles and binder resin. For example, the compounds described in JP-A-2004-331812 and JP-A-2004-163610 can be used.
The antifouling agent can suppress adhesion of dirt and fingerprints by imparting water and oil repellency to the moth-eye structure. For example, compounds described in JP 2012-88699 A can be used.

(Polymerization initiator)
When the polymerizable compound for forming a binder resin is a photopolymerizable compound, the composition for forming an antireflection layer preferably contains a photopolymerization initiator.
As photopolymerization initiators, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, Examples include fluoroamine compounds, aromatic sulfoniums, lophine dimers, onium salts, borate salts, active esters, active halogens, inorganic complexes, and coumarins. Specific examples, preferred embodiments, commercially available products, and the like of the photopolymerization initiator are described in paragraphs [0133] to [0151] of JP-A-2009-098658, and can be suitably used in the present invention as well. it can.
“Latest UV Curing Technology” {Technical Information Association, Inc.} (1991), p. 159, and “UV Curing System” written by Kiyomi Kato (published by the General Technology Center in 1989), p. Various examples are also described in 65-148 and are useful in the present invention.

  A method for applying the composition for forming an antireflection layer is not particularly limited, and a known method can be used. Examples include dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, and die coating.

  From the viewpoint of easy application uniformly, the solid content concentration of the composition for forming an antireflection layer is preferably 10% by mass or more and 80% by mass or less, and more preferably 20% by mass or more and 60% by mass or less.

(Other additives)
The antireflection layer may contain fine particles different from the metal oxide particles described above. In this case, in order not to disturb the shape of the moth-eye structure, it is necessary to be smaller than the metal oxide fine particles. As the other fine particles, particles having an average primary particle size of 50 nm or more and less than 120 nm are preferable because aggregation of metal oxide fine particles may be suppressed and reflectance and haze may be reduced. Specific examples of the other fine particles include, for example, organosilica sol IPA-ST, IPA-ST-L, IPA-ST-ZL, MEK-ST, MEK-ST-L, MEK-ST-ZL, MEK- AC-4130Y, MEK-AC-5140Z, Thruria 2320, 4320, 5320 (above, unfired silica particle dispersion manufactured by Nissan Chemical Co., Ltd.), Seahoster KE-P10 (unfired silica manufactured by Nippon Shokubai Co., Ltd.) Particles), XX-242S (crosslinked polymethyl methacrylate particles manufactured by Sekisui Plastics Co., Ltd.), and the like.

[Polarizer]
The polarizing plate of the present invention is a polarizing plate having a polarizer and at least one protective film for protecting the polarizer, and at least one of the protective films is the antireflection film of the present invention.

Examples of the polarizer include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine-based polarizing film and the dye-based polarizing film can be generally produced using a polyvinyl alcohol film.

[cover glass]
The cover glass of the present invention has the antireflection film of the present invention as a protective film. The base material of the antireflection film may be made of glass, or an antireflection film having a plastic film base material may be pasted on a glass support.

[Image display device]
The image display device of the present invention has the antireflection film or the polarizing plate of the present invention.
The antireflection film and polarizing plate of the present invention are preferably used for image display devices such as liquid crystal display devices (LCD), plasma display panels (PDP), electroluminescence displays (ELD), and cathode ray tube display devices (CRT). In particular, a liquid crystal display device is preferable.
In general, a liquid crystal display device has a liquid crystal cell and two polarizing plates arranged on both sides thereof, and the liquid crystal cell carries a liquid crystal between two electrode substrates. Furthermore, one optically anisotropic layer may be disposed between the liquid crystal cell and one polarizing plate, or two optically anisotropic layers may be disposed between the liquid crystal cell and both polarizing plates. The liquid crystal cell is preferably in TN mode, VA mode, OCB mode, IPS mode or ECB mode.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

[Synthesis of Silica Particles a-1]
A 200 L reactor equipped with a stirrer, a dropping device and a thermometer was charged with 67.54 kg of methyl alcohol and 26.33 kg of 28% by mass aqueous ammonia (water and catalyst), and the liquid temperature was kept at 33 ° C. while stirring. Adjusted. Meanwhile, a dropping device was charged with a solution prepared by dissolving 12.70 kg of tetramethoxysilane in 5.59 kg of methyl alcohol. While maintaining the liquid temperature in the reactor at 33 ° C., the above solution was dropped from the dropping device over 1 hour, and after completion of the dropping, stirring was further performed for 1 hour while maintaining the liquid temperature at the above temperature. Hydrolysis and condensation of methoxysilane was performed to obtain a dispersion containing a silica particle precursor. This dispersion was subjected to air-drying under the conditions of a heating tube temperature of 175 ° C. and a reduced pressure of 200 torr (27 kPa) using an instantaneous vacuum evaporation apparatus (Crox System CVX-8B type manufactured by Hosokawa Micron Co., Ltd.). Particle a-1 was obtained, and the average particle size was 200 nm, and the degree of particle size dispersion (Cv value) was 3.5%.

[Preparation of calcined silica particles b-1]
5 kg of silica particles a-1 were placed in a crucible, fired at 900 ° C. for 1 hour using an electric furnace, cooled, and then ground using a grinder to obtain pre-classified fired silica particles. Furthermore, calcination silica classification b-1 was obtained by performing crushing and classification using a jet crushing and classifying machine (IDS-2 type, manufactured by Nippon Puma Co., Ltd.). The average particle diameter of the obtained silica particles was 200 nm, and the degree of dispersion (Cv value) of the particle diameter was 3.5%.

[Preparation of calcined silica particles b-2]
5 kg of silica particles a-1 were put in a crucible, fired at 900 ° C. for 2 hours using an electric furnace, cooled, and then ground using a grinder to obtain pre-classified fired silica particles. Furthermore, the pulverized silica particles b-2 were obtained by crushing and classifying using a jet pulverizing and classifying machine (IDS-2 type manufactured by Nippon Puma Co., Ltd.). The average particle diameter of the obtained silica particles was 200 nm, and the degree of dispersion (Cv value) of the particle diameter was 3.5%.

[Preparation of calcined silica particles b-3]
5 kg of silica particles a-1 were put into a crucible, fired at 1050 ° C. for 1 hour using an electric furnace, cooled, and then pulverized using a pulverizer to obtain pre-classified sintered silica particles. Furthermore, the pulverized silica particles b-3 were obtained by performing crushing and classification using a jet pulverization classifier (IDS-2 type, manufactured by Nippon Puma Co., Ltd.). The average particle diameter of the obtained silica particles was 200 nm, and the degree of dispersion (Cv value) of the particle diameter was 3.5%.

[Preparation of calcined silica particles b-4]
2 kg each of silica particles b-1 and b-3 were put into a high-speed stirring mixer Spartan mixer (manufactured by DULTON), stirred for 30 minutes and then taken out to obtain calcined silica particles b-4. The average particle diameter of the obtained silica particles was 200 nm, and the degree of dispersion (Cv value) of the particle diameter was 23%.

[Preparation of calcined silica particles b-5]
25 kg of silica-based hollow fine particle dispersion sol (Catalyst Kasei Kogyo Co., Ltd .: Thruria 1420-120, average particle size 120 nm, concentration 20.5 wt%, dispersion medium: isopropanol, particle refractive index 1.20) in a crucible The isopropanol was evaporated in an oven at 100 ° C. Next, after baking for 1 hour at 1050 ° C. using an electric furnace, the mixture was cooled and then pulverized using a pulverizer to obtain pre-classified baked silica particles. Furthermore, pulverized silica particles b-5 were obtained by crushing and classifying using a jet pulverization classifier (IDS-2 type, manufactured by Nippon Puma Co., Ltd.). The average particle diameter of the obtained silica particles was 120 nm, and the degree of dispersion (Cv value) of the particle diameter was 5.0%.

[Production of Silane Coupling Agent-treated Silica Particles c-1]
5 kg of pre-classified sintered silica particles b-2 were charged into a 20 L Henschel mixer (FM20J type, manufactured by Mitsui Mining Co., Ltd.) equipped with a heating jacket. A solution prepared by dissolving 45 g of 3-acryloxypropyltrimethoxysilane (KBM5103 manufactured by Shin-Etsu Chemical Co., Ltd.) in 90 g of methyl alcohol was added dropwise to the stirred silica particles b-2. Then, it heated up to 150 degreeC over about 1 hour, mixing and stirring, and hold | maintained at 150 degreeC for 12 hours, and heat-processed. In the heat treatment, scrapes on the wall surface were scraped while the scraping device was always rotated in the direction opposite to the stirring blade. Moreover, the wall deposits were also scraped off using a spatula as appropriate. After heating, the mixture was cooled and pulverized and classified using a jet pulverizer to obtain silane coupling agent-treated silica particles c-1. The average particle size was 210 nm, and the degree of dispersion (Cv value) of the particle size was 3.7%.

[Measurement of hydroxyl group content on particle surface]
Using solid 29Si NMR, signal intensity Q2 and Q1 were measured under the following conditions to calculate the amount of hydroxyl groups (Q1 × 3 + Q2 × 2).
Measuring method: ²⁹ Si CP / MAS
Observation frequency: ²⁹ Si: 59.63 MHz
Spectral width: 22675.74 Hz
Total number of times: 2000 times Contact time: 5 ms
90 ° pulse: 4.8 μs
Measurement waiting time: 2 seconds MAS rotation speed: 3 kHz
Chemical shift: Q2 is -91 to -94 ppm, Q1 is -100 to -102 ppm

[Measurement of indentation hardness of metal oxide particles]
8 g of each metal oxide particle, 0.3 g of Irgacure 184 (manufactured by BASF Japan Ltd.), 7.7 g of KAYARAD PET30 (manufactured by Nippon Kayaku Co., Ltd.) were added to 91 g of ethanol, and after stirring for 10 minutes, The dispersion was carried out for 10 minutes with a sonic disperser to obtain a 15% by mass dispersion. This dispersion W period was applied to a glass plate at a wet application amount of about 3 ml / m ² , and an irradiation amount of 600 mJ / cm ² was applied with an air-cooled metal halide lamp while purging with nitrogen so that the oxygen concentration was 0.1 vol% or less. Cured by UV irradiation. Thereafter, it was observed with SEM that the metal oxide particles were not stacked in one or more stages. This sample was measured for indentation hardness of the metal oxide particles using a triboindenter (TI-950 manufactured by Heiditron Co., Ltd.) under the measurement conditions of a diamond indenter with a diameter of 1 μm and an indentation load of 0.05 mN.

[Preparation of antireflection films A-1 and A-2]
10 g of silica particles a-1 were added to 10 g of ethanol placed in a glass container, and ultrasonic waves were applied until no solid matter could be visually confirmed to obtain a milky white suspension. Subsequently, 15 g of acrylic monomer (M-350 manufactured by Toagosei Co., Ltd.) was added to the suspension in the glass container, stirred well, and then placed in a dryer maintained at 45 ° C. together with the glass container. After evaporating about 5 g of ethanol from the suspension, 0.2 g of photopolymerization initiator (trade name “DAROCUR1173” manufactured by Ciba Specialty Chemicals) was added to prevent the silica particles from being dispersed in the acrylic monomer. A layer forming coating solution A-1 was obtained.

  Next, the coating liquid A-1 for forming an antireflection layer is dropped on the surface of a 100 mm square glass substrate (alkali glass manufactured by Asahi Techno Glass Co., Ltd.) that has been surface cleaned with a UV / ozone cleaner in advance, and a spin coater. , The glass substrate was rotated under the conditions of 200 rpm for 120 seconds and then 600 rpm for 120 seconds to apply the coating solution A-1 for forming an antireflection layer over the entire surface of the glass substrate. Thereafter, the substrate coated with the antireflection layer forming coating solution A-1 is conveyed to a glove box in a nitrogen atmosphere, and the acrylic monomer is cured by photopolymerization by irradiating with a UV cure lamp in the glove box for 1 minute. A transparent resin film in which silica particles were dispersed in an acrylic resin on a glass substrate was obtained.

  Next, the surface of the obtained transparent resin film is subjected to plasma treatment using a high-frequency plasma apparatus under conditions of 13.56 MHz to etch the acrylic resin in the transparent resin film, thereby revealing the uneven shape on the surface. Thus, an antireflection film A-1 was obtained. The plasma treatment was performed by applying a high frequency of 50 W for 30 seconds under a pressure of 2.7 Pa while introducing a gas having a composition of oxygen: argon = 1: 1. Moreover, the film thickness of the obtained antireflection layer was 20 μm.

  An antireflection film A-2 was produced in the same manner as the antireflection film A-1, except that the silica particles b-1 were used instead of the silica particles a-1 (coating liquid A-2 for forming an antireflection layer). The film thickness of the obtained antireflection film was 20 μm.

[Preparation of Antireflection Films B-1 to B-4, C-1 to C-11]
(Preparation of coating solution for antireflection layer formation)
Each component is put into a mixing tank so as to have the composition shown in Table 1 below, stirred for 60 minutes, dispersed with an ultrasonic disperser for 30 minutes, and filtered through a polypropylene filter having a pore size of 5 μm to form a coating solution for forming an antireflection layer. It was.
In the following Table 1, the numerical value of each component represents the added amount (parts by mass). The unit of the coating solution concentration is “mass%”. For metal oxide particles, the hydroxyl group equivalent, indentation hardness, and average primary particle size dispersity Cv value are listed.

The compounds used are shown below.
KAYARAD PET30 (manufactured by Nippon Kayaku Co., Ltd.): a mixture of 60% pentaerythritol triacrylate and 40% pentaerythritol tetraacrylate KAYARAD DPHA (manufactured by Nippon Kayaku Co., Ltd.): 50% dipentaerythritol pentaacrylate Aronix M-405 (manufactured by Toagosei Co., Ltd.): A mixture of 15% dipentaerythritol pentaacrylate and 85% dipentaerythritol hexaacrylate Aronix M-450 (Toagosei Co., Ltd.) ) Manufactured by :) Mixture of 5% pentaerythritol triacrylate and 95% pentaerythritol tetraacrylate Seahoster KE-S30 (manufactured by Nippon Shokubai Co., Ltd.): average primary particle size of about 300 nm
Irgacure 184: Photopolymerization initiator (manufactured by BASF Japan Ltd.)

(Preparation of antireflection films B-1 to B-4)
On a cellulose triacetate film (TDH60UF, manufactured by FUJIFILM Corporation) as a transparent substrate having a thickness of 60 μm, an anti-reflection layer-forming coating solution B-1 is applied at a wet coating amount of about 2.8 ml / m ² using a gravure coater. After being coated with and dried at 120 ° C. for 5 minutes, it was cured by irradiating with an ultraviolet ray with an irradiation amount of 600 mJ / cm ² with an air-cooled metal halide lamp while purging with nitrogen so that the atmosphere had an oxygen concentration of 0.1% by volume or less. An antireflection film B-1 was produced. At this time, the amount of wet coating was finely adjusted to measure the particle occupancy, and the highest was adopted as the antireflection film B-1. Antireflection films B-2 to B-4 were produced in the same manner except that the antireflection layer forming coating solutions B-2 to B-4 were used instead of the antireflection layer forming coating solution B-1.

(Preparation of composition for forming hard coat layer)
Methyl acetate 10.5 parts by mass, MEK 10.5 parts by mass, NK ester A-TMMT (made by Shin-Nakamura Chemical Co., Ltd.) 22.52 parts by mass, AD-TMP (made by Shin-Nakamura Chemical Co., Ltd.) ) 6.30 parts by mass and 0.84 parts by mass of Irgacure 184 were added, stirred, and filtered through a polypropylene filter having a pore size of 0.4 μm to obtain a hard coat layer coating solution (solid content concentration: 58% by mass). .

(Preparation of antireflection films C-1 to C-11)
A cellulose triacetate film (TDH60UF, manufactured by Fuji Film Co., Ltd.) is coated with a coating solution for forming a hard coat layer and cured by irradiating an ultraviolet ray with an irradiation amount of 30 mJ / cm ² with an air-cooled metal halide lamp while purging with nitrogen. A hard coat layer having a thickness of 6 μm was formed. Thus, the base material with a hard-coat layer was produced.
On the hard coat layer of the substrate with a hard coat layer, the antireflection layer forming coating solution C-1 was applied at a wet application amount of about 2.8 ml / m ² using a gravure coater, and dried at 120 ° C. for 5 minutes. Thereafter, the film was cured by irradiating with an ultraviolet ray with an irradiation amount of 600 mJ / cm ² with an air-cooled metal halide lamp while purging with nitrogen so that the atmosphere had an oxygen concentration of 0.1% by volume or less to produce an antireflection film C-1. At this time, the amount of wet coating was finely adjusted to measure the particle occupancy, and the highest was adopted as the antireflection film C-1. The coating liquids C-2 to C-11 for forming the antireflection layer were used in place of the coating liquid C-1 for forming the antireflection layer, and the wet coating amount was the same as when the antireflection film C-1 was formed. Antireflection films C-2 to C-11 were produced in the same manner.

(Evaluation of antireflection film)
Various characteristics of the antireflection film were evaluated by the following methods. The results are shown in Table 2.

(Integral reflectance)
The back surface of the antireflection film (cellulose triacetate film side) is roughened with sandpaper, then treated with black ink, and the back surface reflection is eliminated. The ARV-474 was attached, and the integrated reflectance at an incident angle of 5 ° was measured in the wavelength region of 380 to 780 nm, and the average reflectance was calculated to evaluate the antireflection property.

(Haze)
The uniformity of the surface was evaluated by the haze value. When the particles are aggregated and non-uniform, the haze increases. The total haze value (%) of the obtained film was measured according to JIS-K7136. Nippon Denshoku Industries Co., Ltd. haze meter NDH4000 was used for the apparatus.
Haze value is 2% or less: No cloudiness and excellent surface uniformity.
The haze value is 5% or less, although there is a slight cloudiness, but there is no problem in appearance.
The haze value is larger than 5% ... The cloudiness is strong and the appearance is impaired.

(Durability to pressure in the thickness direction of the moth-eye structure)
The substrate side of the antireflection film sample is attached to a glass plate, and a scratch test is performed on the antireflection layer surface using a diamond indenter with a diameter of 25 μm under the conditions of 20 g load and 810 mm / min. Were observed and evaluated according to the following criteria.
A: After the test you can't see the rest B: You can see the weak after the test but there is no problem

(B / A, half width of A distribution)
The antireflection film sample was cut with a microtome to obtain a cross section, and the cross section was etched for 10 minutes after carbon deposition. Using a scanning electron microscope (SEM), 20 fields of view were observed and photographed at a magnification of 5000 times. In the obtained image, at the interface between the air and the sample, the distance A between the vertices of the adjacent convex portions and the distance B between the vertices of the adjacent convex portions and the concave portion are measured by 100 points, and B / A It was calculated as an average value. The half-value width of the A distribution was also calculated.

(Pencil hardness)
The pencil hardness evaluation described in JIS K5400 was performed. The antireflection film sample was conditioned at a temperature of 25 ° C. and a humidity of 60% RH for 3 hours, then tested on the antireflection layer surface using a test pencil specified in JIS S6006, and evaluated according to the following criteria.
A: After the test you can't see the rest B: You can see the weak after the test but there is no problem

When Comparative Samples A-1 and A-2 are compared, the durability against pressure in the thickness direction of the moth-eye structure is improved by increasing the indentation hardness of the particles, and the collapsing of the particles can be suppressed. Thus, it can be seen that the dispersibility is poor due to the absence of haze and haze and reflectance are deteriorated. On the other hand, in the example samples B-1 to B-4 and C-1 to C-4 of the present invention, the binder resin has a hydroxyl group, so that the reflectance and haze are excellent, and B-1, B- It can be seen that the 2, C-1, and C-2 samples are particularly excellent.
Regarding the indentation hardness of the particles, Example Sample C-2 showed good durability in the thickness direction, C-5 and C-6 samples were more excellent, and the pencil hardness test was also excellent. It was confirmed that there was an effect. Further, by comparing the comparative sample C-11 at the same time, it was confirmed that this effect was dependent on the indentation hardness of the particles, not on the decrease in the amount of hydroxyl on the particle surface by firing.
In Example Sample C-8, the reflectance is most excellent, which is considered to be due to the large B / A.

[Example 2]
[Synthesis of Silica Particles a-7]
A 200-liter reactor equipped with a stirrer, a dropping device and a thermometer was charged with 101.01 kg of methyl alcohol and 6.58 kg of 28% by mass aqueous ammonia (water and catalyst), and the liquid temperature was kept at 33 ° C. while stirring. Adjusted. Meanwhile, a dropping device was charged with a solution obtained by dissolving 3.18 kg of tetramethoxysilane in 1.40 kg of methyl alcohol. While maintaining the liquid temperature in the reactor at 33 ° C., the above solution was dropped from a dropping device over 45 minutes to hydrolyze and condense tetramethoxysilane, thereby obtaining a dispersion containing a silica particle precursor. . This dispersion was subjected to air-drying under the conditions of a heating tube temperature of 175 ° C. and a reduced pressure of 200 torr (27 kPa) using an instantaneous vacuum evaporation apparatus (Crox System CVX-8B type manufactured by Hosokawa Micron Co., Ltd.). Particle a-7 was obtained, and the average particle diameter was 90 nm, and the degree of dispersion of particle diameter (Cv value) was 8%.

[Synthesis of Silica Particles a-8]
A 200 L reactor equipped with a stirrer, a dropping device and a thermometer was charged with 108.93 kg of methyl alcohol and 2.37 kg of 28% by mass ammonia water (water and catalyst), and the liquid temperature was kept at 25 ° C. while stirring. Adjusted. On the other hand, a dropping device was charged with a solution prepared by dissolving 1.14 kg of tetramethoxysilane in 0.50 kg of methyl alcohol. While maintaining the liquid temperature in the reactor at 33 ° C., the above solution was dropped from the dropping device over 1 hour, and after completion of the dropping, stirring was further performed for 1 hour while maintaining the liquid temperature at the above temperature. Hydrolysis and condensation of methoxysilane was performed to obtain a dispersion containing a silica particle precursor. This dispersion was subjected to air-drying under the conditions of a heating tube temperature of 175 ° C. and a reduced pressure of 200 torr (27 kPa) using an instantaneous vacuum evaporation apparatus (Crox System CVX-8B type manufactured by Hosokawa Micron Co., Ltd.). Particle a-8 was obtained.

[Synthesis of Silica Particles a-9 to a-11]
Tetramethoxysilane was hydrolyzed and condensed by the same method as the synthesis of silica particles a-7, except that the dropping time of the above solution was changed from a dropping device to 8 minutes, 20 minutes, and 50 minutes, respectively. Silica particles a-9 to a-11 were obtained.

[Synthesis of Silica Particles a-12]
Except for performing the hydrolysis and condensation of tetramethoxysilane by changing the dropping time of the above solution from the dropping device to 60 minutes, and stirring for 20 minutes while maintaining the liquid temperature at the above temperature after the completion of dropping. Silica particles a-12 were obtained in the same manner as in the synthesis of silica particles a-7.

[Synthesis of Silica Particles a-13]
Silica particles a-13 were obtained by the same method as the synthesis of silica particles a-12, except that the stirring time after the completion of dropping was further changed to 40 minutes.

[Preparation of calcined silica particles b-7]
5 kg of silica particles a-7 were put in a crucible, fired at 900 ° C. for 1 hour using an electric furnace, cooled, and then ground using a grinder to obtain pre-classified fired silica particles. Furthermore, the pulverized silica particles b-7 were obtained by crushing and classifying using a jet pulverization classifier (IDS-2 type manufactured by Nippon Pneumatic Co., Ltd.). The average particle diameter of the obtained silica particles was 90 nm, and the degree of dispersion (Cv value) of the particle diameter was 8%.

[Preparation of calcined silica particles b-8 to b-13]
The silica particles a-7 were changed to silica particles a-8 to a-13, respectively, and the calcined silica particles b-8 to b- were prepared in the same manner as the calcined silica particles b-7, except that the firing time was changed to 2 hours. 13 was produced.

[Preparation of Silane Coupling Agent-treated Silica Particles c-8]
5 kg of pre-classified sintered silica particles b-8 were charged into a 20 L Henschel mixer (FM20J type, manufactured by Mitsui Mining Co., Ltd.) equipped with a heating jacket. While the calcined silica particles b-8 were being stirred, a solution prepared by dissolving 600 g of 3-acryloxypropyltrimethoxysilane (KBM5103 manufactured by Shin-Etsu Chemical Co., Ltd.) in 1200 g of methyl alcohol was added dropwise and mixed. Then, it heated up to 150 degreeC over about 1 hour, mixing and stirring, and hold | maintained at 150 degreeC for 12 hours, and heat-processed. In the heat treatment, scrapes on the wall surface were scraped while the scraping device was always rotated in the direction opposite to the stirring blade. Moreover, the wall deposits were also scraped off using a spatula as appropriate. After heating, the mixture was cooled and pulverized and classified using a jet pulverizer to obtain silane coupling agent-treated silica particles c-8.

[Preparation of Silica Coupling Agent-treated Silica Particles c-9 to c-13]
The calcined silica particles b-8, the calcined silica particles b-9 to b-13, the 3-acryloxypropyltrimethoxysilane 180 g, 129 g, 95 g, 82 g, and 75 g, respectively, and the methyl alcohol 360 g and 257 g, respectively. Except having changed into 189g, 164g, 150g, the baking silica particle silane coupling agent process silica particle c-9 to c-13 was produced by the method similar to the silane coupling agent process silica particle c-8.

[Preparation of Antireflection Films B-5 to B-6, C-12 to C-24]
(Preparation of coating solution for antireflection layer formation)
Each component is put into a mixing tank so as to have the composition shown in Table 4 below, stirred for 60 minutes, dispersed by an ultrasonic disperser for 30 minutes, and filtered through a polypropylene filter having a pore size of 5 μm to form a coating solution for forming an antireflection layer. It was.

  In the following Table 4, the numerical value of each component represents the amount (parts by mass) added. The unit of the coating solution concentration is “mass%”. For the metal oxide particles and other particles, the average primary particle size, hydroxyl group equivalent, indentation hardness, and dispersion degree Cv value of the average primary particle size are described.

(Frequency of fine particles)
The frequency of the fine particles is calculated as a ratio of the numbers when all the metal oxide fine particles to be blended are regarded as having an average primary particle size. That is, for example, with respect to 1 part by weight of fine particles having an average primary particle size r1 (r1 is 120 nm to 250 nm) and specific gravity s1, fine particles having an average primary particle size r2 (r2 is 50 nm to less than 120 nm) and specific gravity s2 are X weight. In the case of partial blending, the frequency is represented by (r1 ³ · s1 · X) / (r2 ³ · s2).
Moreover, when measuring the frequency of the metal oxide particle contained in an antireflection layer, it can measure with an electron micrograph. For example, the antireflection film is observed from the surface side by SEM observation at an appropriate magnification (about 5000 times), the diameter of each of the 100 primary particles is measured, the volume is calculated, and the average of fine particles of 120 nm to 250 nm is calculated. The primary particle size can be determined as r1, and the average primary particle size of fine particles having a particle size of 50 nm or more and less than 120 nm can be determined as r2.

The compounds used are shown below.
MEK-AC-5140Z (manufactured by Nissan Chemical Co., Ltd.): methacryloyl group modification, 40% MEK dispersion of unfired silica particles having an average primary particle size of 85 nm XX-242S (manufactured by Sekisui Plastics Co., Ltd.): Crosslinked polymethyl methacrylate particles having an average primary particle size of 100 nm

  Antireflection films B-5 to B-6 were produced in the same manner as the antireflection films B-1 to B-4.

  Antireflection films C-12 to C-24 were produced in the same manner as the antireflection films C-1 to C-11.

(Evaluation of antireflection film)
Various characteristics of the antireflection film were evaluated by the following methods. The results are shown in Table 5.

When the working samples B-2, B-5, and B-6 were compared, the reflectance and haze were improved when the fine particles having an average primary particle size of 200 nm and the fine particles having an average primary particle size of 50 nm or more and less than 120 nm were combined. It can be seen that the dispersibility of is improved. When the working samples C-12 to C-18 are compared, the reflectance and haze are better when the fine primary particles having an average primary particle size of 210 nm and the fine particles having an average primary particle size of 50 nm or more and less than 120 nm are combined even when the hard coat is provided. It turns out that it improves, and also it turns out that it is especially excellent when the particle size is 70-110 nm. Furthermore, when these are compared with execution sample C-19, C-20, it turns out that it is excellent in a reflectance and a haze. From this result, it can be seen that those having approximately the same hydroxyl group amount and firing conditions on the surfaces of the fine particles of 210 nm and fine particles of 50 nm or more and less than 120 nm have a higher effect of suppressing aggregation than using different ones. By comparing the working samples C-16 and C-21 to C-23, it can be seen that the frequency of fine particles of 50 nm or more and less than 120 nm with respect to fine particles of 120 or more and 250 nm or less is best 2 to 5 times.

DESCRIPTION OF SYMBOLS 1 Base material 2 Antireflection layer 3 Metal oxide particle 4 Binder resin 10 Antireflection film A Distance between the vertices of the adjacent convex portions B Distance between the centers of the adjacent convex portions and the concave portions

Claims (18)

An antireflection film comprising a base material, an antireflection layer containing a binder resin and metal oxide particles having an average primary particle size of 50 nm to 250 nm,
The surface of the metal oxide particles has a hydroxyl group amount of 1.00 × 10 ⁻¹ or less,
The indentation hardness of the metal oxide particles is 400 MPa or more,
The binder resin is a resin having a hydroxyl group,
The antireflection layer is an antireflection film having a moth-eye structure having a concavo-convex shape formed by the metal oxide particles on a surface opposite to the interface on the substrate side.   The concave-convex shape of the antireflection layer is such that B / A, which is a ratio of the distance A between the apexes of adjacent convex portions and the distance B between the centers of the adjacent convex portions and the concave portions, is 0.5 or more. The antireflection film according to claim 1.   The antireflection film according to claim 1 or 2, wherein the metal oxide particles contain only metal oxide particles having a primary particle size of 50 nm or more and 250 nm or less.   The antireflection film according to claim 1, wherein the metal oxide particles are silica particles.   The antireflection film according to claim 1, wherein the metal oxide particles are fired silica particles.   The antireflection film according to any one of claims 1 to 5, wherein the metal oxide particles are fired silica particles whose surface is modified with a compound having a (meth) acryloyl group.   The antireflection film according to claim 2, wherein the half width of the distribution of the distance A is 200 nm or less.   The binder resin is a resin obtained by polymerizing a polymerizable compound having at least one of a group having an ethylenically unsaturated double bond and an epoxy group as a polymerizable group. The antireflection film as described in 1. The antireflection film according to claim 8, wherein one molecule of the polymerizable compound has a hydroxyl group equivalent of 1 to 10,000.   The antireflection film according to claim 1, further comprising a hard coat layer between the substrate and the antireflection layer.   Polarized light having a polarizer and at least one protective film for protecting the polarizer, wherein at least one of the protective films is the antireflection film according to any one of claims 1 to 10. Board.   The cover glass which has an antireflection film of any one of Claims 1-10 as a protective film.   The image display apparatus which has an antireflection film of any one of Claims 1-10, or a polarizing plate of Claim 11. A method for producing an antireflection film comprising a base material, and an antireflection layer containing a binder resin and metal oxide particles having an average primary particle size of 50 nm to 250 nm,
The surface of the metal oxide particles has a hydroxyl group amount of 1.00 × 10 ⁻¹ or less,
The indentation hardness of the metal oxide particles is 400 MPa or more,
The binder resin is a resin having a hydroxyl group,
The antireflection layer has a moth-eye structure consisting of a concavo-convex shape formed by the metal oxide particles on the surface opposite to the interface on the substrate side,
On the base material, a composition for forming an antireflection layer containing a polymerizable compound for forming a binder resin having a polymerizable functional group and metal oxide particles having an average primary particle size of 50 nm to 250 nm is applied. The manufacturing method of the antireflection film which has a process.   The metal oxide particles include both metal oxide fine particles having an average primary particle size of 120 nm to 250 nm and metal oxide particles having an average primary particle size of 50 nm to less than 120 nm. The antireflection film according to any one of the above. The antireflection film according to claim 15, wherein the metal oxide particles having an average primary particle size of 50 nm or more and less than 120 nm have a hydroxyl group amount of 1.00 × 10 ⁻¹ or less and an indentation hardness of 400 MPa or more. The antireflection film according to claim 15, wherein the metal oxide particles having an average primary particle size of 50 nm or more and less than 120 nm have a hydroxyl group amount of more than 1.00 × 10 ⁻¹ or an indentation hardness of less than 400 MPa.   18. The metal oxide fine particles having an average primary particle size of 120 nm or more and 250 nm or less, the metal oxide particles having an average primary particle size of 50 nm or more and less than 120 nm at a frequency of 2 to 5 times. 2. The antireflection film according to item 1.

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