WO2013051620A1

WO2013051620A1 - Method of manufacturing object with low reflection film

Info

Publication number: WO2013051620A1
Application number: PCT/JP2012/075680
Authority: WO
Inventors: 義美大谷; 敏本谷
Original assignee: 旭硝子株式会社
Priority date: 2011-10-03
Filing date: 2012-10-03
Publication date: 2013-04-11
Also published as: JPWO2013051620A1; KR20140088862A; CN103842098A

Abstract

Provided is a method of manufacturing an object with a low reflection film, with which it is possible to form a low reflection film with which it is possible to handle a wide substrate, have a comparatively rapid speed of conveyance of the substrate, a comparatively low volume of required coating compound, a comparatively short time for drying, firing, and/or application, and a uniform thickness, as well as have superior thickness controllability whereby a low reflection film having thickness which is arbitrarily optically designable is easily formed. When forming, upon a substrate (2) which is conveyed in a prescribed direction, a low reflection film by applying a coating compound (20) by a coating roll (14) of a reverse roll coater (10), the rotation speed of the coating roll (14) is made slower than the conveyance speed of the substrate (2), and the coating compound (20) includes a dispersal medium (a), fine particles (b) which are dispersed in the dispersal medium (a), and a binder (c) which is either dissolved or dispersed in the dispersal medium (a), wherein the viscosity is 1-10mPa•s.

Description

Method for manufacturing article with low reflection film

The present invention relates to a method of manufacturing an article having a low reflection film on a substrate.

Articles having an antireflection function for the purpose of reducing external light reflection and improving light transmittance have been put into practical use. As a method for imparting an antireflection function, a method of forming a low reflection film on a substrate by a wet coating method (spin coating method, spray coating method, roll coating method, etc.) is known.

The spin coating method is a method of applying a coating composition for forming a low reflection film on a substrate by centrifugal force by dropping the coating composition for forming a low reflection film on the substrate and rotating the substrate. .
The spray coating method is a method of applying a coating composition for forming a low reflection film on a substrate by spraying the coating composition for forming a low reflection film from a spray head onto the substrate conveyed in a predetermined direction. .
In the roll coating method, a coating composition for forming a low reflection film is applied onto a substrate by transferring the coating composition for forming a low reflection film on the surface of the coating roll onto the substrate conveyed in a predetermined direction. Is the method.

However, the spin coating method has the following problems.
-When a base material becomes large, it will become difficult to rotate a base material.
-The low reflective film tends to be thick at the periphery of the substrate, and the film thickness uniformity of the low reflective film is inferior.
-Since the excess coating composition for forming a low reflection film is blown off from the substrate by centrifugal force, the amount of the coating composition for forming a low reflection film required is increased.

The spray coating method has the following problems.
-Since it is necessary to reciprocate the spray head in the width direction of the base material, in order to form a low reflection film uniformly on a wide base material, a large number of spray heads are arranged along the transport direction of the base material. Or, it is necessary to slow down the conveying speed of the substrate.
-Since there are many coating compositions for forming a low reflection film that do not adhere to the substrate and scatter in the atmosphere, the amount of coating composition for forming a low reflection film that is required increases.

A roll coating method is an example of a wet coating method that can handle a wide range of substrates, can relatively fasten the conveyance speed of the substrate, and requires a relatively small amount of the coating composition for forming a low reflection film. .
However, the roll coating method has the following problems.
・ Adjustment of the gap between the substrate and the coating roll is difficult, and the film thickness uniformity of the low reflective film is poor.
When the viscosity of the coating composition for forming a low reflection film is low, it is difficult to form a low reflection film having an arbitrary film thickness that can be optically designed. That is, the film thickness controllability is poor.
・ In order to form a low-reflection film having an arbitrary film thickness that can be optically designed, if the viscosity of the coating composition for forming a low-reflection film is increased or overcoated, drying or baking time or coating time is increased. become longer.

The following method has been proposed as a roll coating method capable of forming a metal oxide film having a uniform film thickness.
A method of forming a metal oxide film by applying a coating composition containing a metal compound and an organic solvent by a coating roll of a reverse roll coater on a substrate conveyed in a predetermined direction, and baking the coating composition, The concentration of the metal compound in the coating composition (as oxide) is 0.1 to 10% by mass, the viscosity of the coating composition is 0.1 to 100 mPa · s, and the rotation speed of the coating roll is 2 to 55 m / min, the substrate transport speed is 1 to 30 m / min, and the rotation speed of the coating roll is higher than the substrate transport speed (see Patent Document 1).

However, in this method, when the viscosity of the coating composition is lowered, there is a problem that it is difficult to form a low reflection film having an arbitrary film thickness that can be optically designed, that is, the film thickness controllability is poor.

Japanese Unexamined Patent Publication No. 07-068219

The present invention can deal with a wide range of substrates, can relatively fast the conveyance speed of the substrate, requires a relatively small amount of coating composition, relatively short drying or baking time and application time, A method for producing an article with a low-reflection film that can form a low-reflection film having a uniform film thickness and is easy to form a low-reflection film having an arbitrary film thickness that can be optically designed (that is, excellent in film thickness controllability) provide.

The method for producing an article with a low reflection film of the present invention is a method for producing an article having a low reflection film on a substrate, and the method comprises a reverse roll coater on the substrate conveyed in a predetermined direction. The coating composition is applied by a coating roll to form the low reflection film, and the dispersion medium (a) and fine particles (b) dispersed in the dispersion medium (a) are formed as the coating composition. And a binder (c) dissolved or dispersed in the dispersion medium (a), and using a coating liquid having a viscosity of 1.0 to 10.0 mPa · s, and the paint on the substrate in the step The rotational speed of the coating roll when applying the composition (that is, the peripheral speed. In the present specification, “rotational speed” means the peripheral speed) is made slower than the transport speed of the substrate. Features.

The coating composition preferably further contains a terpene derivative (d) dissolved or dispersed in the dispersion medium (a).
The amount of the terpene derivative (d) is preferably 0.01 to 2 parts by mass with respect to 1 part by mass of the solid content of the coating composition.
The solid content concentration of the coating composition is preferably 1 to 9% by mass.
The mass ratio of the fine particles (b) to the binder (c) (fine particles (b) / binder (c)) is preferably 10/90 to 95/5.

The conveying speed of the substrate is preferably 3 to 20 m / min.
The rotation speed of the coating roll is preferably 0.28 times or more and 0.98 times or less the conveyance speed of the base material.
The surface hardness (JIS-A standard) of the coating roll is preferably 10 to 70.
It is preferable that the base material is a template glass having a satin pattern on at least one surface.
The term “to” indicating the above numerical range is used in the sense that the numerical values described before and after it are used as the lower limit value and the upper limit value. Unless otherwise specified, “to” is the same in the following specification. Used with meaning.

According to the method for producing an article with a low reflection film of the present invention, it is possible to deal with a wide substrate, the substrate conveyance speed can be relatively fast, the amount of the coating composition required is relatively small, and drying Or, the baking time and the coating time are relatively short, a low reflection film having a uniform film thickness can be formed, and it is easy to form a low reflection film having an arbitrary film thickness that can be optically designed, that is, excellent in film thickness controllability. .

It is sectional drawing which shows an example of the articles | goods with a low reflection film in this invention. It is sectional drawing which shows the other example of the articles | goods with a low reflection film in this invention. It is the schematic which shows an example of a reverse roll coater.

<Article with low reflective film>
FIG. 1 is a cross-sectional view showing an example of an article with a low reflection film obtained by the production method of the present invention. The article 1 with a low reflection film has a base material 2 and a low reflection film 3 formed on the surface of the base material 2.

(Base material)
Examples of the material for the substrate 2 include glass, metal, resin, silicon, wood, paper, and the like. Examples of the glass include soda lime glass, borosilicate glass, aluminosilicate glass, alkali-free glass, and mixed alkali glass. Examples of the resin include polyethylene terephthalate, polycarbonate, triacetyl cellulose, polymethyl methacrylate, and the like.
Although there is no restriction | limiting in particular as a shape of the base material 2, Generally, a board, a film, etc. are mentioned.

As the base material 2 for the cover glass of the solar cell, a satin-patterned template glass having an uneven surface is preferable. As the glass, the soda lime glass (ie, high transparency) having a lower iron component ratio than the soda lime glass (commonly referred to as blue plate glass) used for ordinary window glass or the like as the material of the template glass. Transmission glass, commonly called white plate glass) is preferred. The white plate glass is expressed in terms of mass percentage based on oxide, SiO ₂ : 65 to 75%, Al ₂ O ₃ : 0 to 10%, CaO: 5 to 15%, MgO: 0 to 15%, Na ₂ O: 10 ~ 20%, K ₂ O: 0 to 3%, Li ₂ O: 0 to 5%, Fe ₂ O ₃ : 0 to 3%, TiO ₂ : 0 to 5%, CeO ₂ : 0 to 3%, BaO: 0 to 5%, SrO: 0 to 5%, B ₂ O ₃ : 0 to 15%, ZnO: 0 to 5%, ZrO ₂ : 0 to 5%, SnO ₂ : 0 to 3%, SO ₃ : 0 to It is preferable to have a composition of 0.5%. Further, when the base material 2 is non-alkali glass, it is expressed in terms of mass percentage on the basis of oxide, SiO ₂ : 39 to 70%, Al ₂ O ₃ : 3 to 25%, B ₂ O ₃ : 1 to 30% MgO: 0 to 10%, CaO: 0 to 17%, SrO: 0 to 20%, BaO: 0 to 30%. Further, when the base material 2 is a mixed alkali glass, it is expressed in terms of mass percentage on the basis of oxide, SiO ₂ : 50 to 75%, Al ₂ O ₃ : 0 to 15%, MgO + CaO + SrO + BaO + ZnO: 6 to 24%, Na It is preferable to have a composition of ₂ O + K ₂ O: 6 to 24%.

As shown in FIG. 2, the substrate 2 may have a functional layer 5 on the surface of the substrate body 4.
Examples of the functional layer 5 include an undercoat layer, an adhesion improving layer, and a protective layer.
The undercoat layer functions as an alkali barrier layer or a wide band low refractive index layer. The undercoat layer is preferably a layer formed by applying an undercoat coating composition containing a hydrolyzate of alkoxysilane (sol-gel silica, that is, a silica precursor by a sol-gel method) on a substrate. When a coating composition for a low reflection film, which will be described later, is applied on the undercoat layer, the undercoat layer may be baked in advance or may remain wet. When a coating composition for a low reflection film is applied on the undercoat layer, the application temperature (that is, the substrate temperature during application) is preferably room temperature to 80 ° C., and the firing temperature of the applied coating film is 30 to 700 ° C. is preferable. The thickness of the undercoat layer is preferably 10 to 500 nm.

(Low reflective film)
The low-reflection film 3 is a single-layer film containing a binder (c) or a fired product thereof and fine particles (b), which is formed by applying a coating composition coating solution described later once. preferable. When the binder is a hydrolyzate of alkoxysilane, the low reflection film 3 is a film in which the fine particles (b) are dispersed in a matrix made of a calcined product of the alkoxysilane hydrolyzate (SiO ₂ ). When the binder is resin, the low reflection film 3 is a film in which fine particles (b) are dispersed in a matrix made of resin.

The film thickness of the low reflection film 3 is preferably 50 to 300 nm, more preferably 80 to 200 nm. If the film thickness of the low reflection film 3 is 50 nm or more, light interference occurs and antireflection performance is exhibited. If the film thickness of the low reflective film 3 is 300 nm or less, the film can be formed without generating cracks.
The film thickness of the low reflection film 3 is measured by a reflection spectral film thickness meter.
The reflectance of the low reflective film 3 is the lowest value (so-called bottom reflectance) in the wavelength range of 300 to 1200 nm, preferably 2.6% or less, and more preferably 1.0%.

<Method for producing article with low reflection film>
In the method for producing an article with a low reflection film according to the present invention, a coating liquid of a coating composition, which will be described later, is applied onto a substrate 2 conveyed in a predetermined direction by a coating roll of a reverse roll coater, In this method, the low reflection film 3 is formed by baking or drying and curing as necessary.

(Reverse roll coater)
FIG. 3 is a schematic diagram illustrating an example of a reverse roll coater.
The reverse roll coater 10 is disposed with a predetermined gap above the conveyor belt 12 such that the rotation axis direction is orthogonal to the traveling direction of the conveyor belt 12 and a conveyor belt 12 that conveys the substrate 2 in a predetermined direction. A coating roll 14 that rotates in a direction opposite to the direction of travel of the conveyor belt 12; and is disposed downstream of the coating roll 14 in the direction of travel of the transport belt 12, and with a predetermined indentation thickness with respect to the coating roll 14 A doctor roll 16 (also referred to as a metalling roll) that is in contact; a backup roll that is disposed below the coating roll 14 via the conveyor belt 12 so as to be in contact with the conveyor belt 12 and rotates in the same direction as the traveling direction of the conveyor belt 12 A liquid reservoir for storing the coating composition 20 supplied to the surface of the doctor roll 16; A first doctor blade 22 arranged to contact the surface of the upper half of the doctor roll 16 so as to be formed between the first roll 16 and the surface of the coating roll 14 not transferred to the substrate 2. In order to scrape off the coating composition 20, a second doctor blade 24 disposed so as to contact the surface of the coating roll 14 is provided.
Instead of the conveyance belt 12, a plurality of conveyance rolls may be arranged in the conveyance direction of the base material 2 so that the rotation axis direction is orthogonal to the traveling direction of the conveyance belt 12.

(Application method)
In the reverse roll coater 10, the coating composition 20 is applied on the surface of the substrate 2 as described below, and a coating film is formed.
The coating composition 20 is supplied to the surface of the doctor roll 16 from above the doctor roll 16. A predetermined amount of the coating composition 20 adheres to the surface of the doctor roll 16 and moves between the doctor roll 16 and the first doctor blade 22 toward the coating roll 14 as the doctor roll 16 rotates. At this time, since the movement of the coating composition 20 is regulated by the first doctor blade 22, the coating composition 20 that could not pass between the doctor roll 16 and the first doctor blade 22 is separated from the doctor roll 16. It collects between the first doctor blade 22 and a liquid reservoir is formed.

The coating composition 20 adhered to the surface of the doctor roll 16 and moved to the coating roll 14 side moves to the surface of the coating roll 14 while maintaining a predetermined amount between the coating roll 14 and the doctor roll 16. To do. At this time, since the transfer of the coating composition 20 is regulated by the doctor roll 16, the coating composition 20 that could not pass between the coating roll 14 and the doctor roll 16 is between the coating roll 14 and the doctor roll 16. And a liquid reservoir is formed. The coating composition 20 transferred to the surface of the coating roll 14 moves to the side of the conveyor belt 12 as the coating roll 14 rotates.

The coating composition 20 adhered to the surface of the coating roll 14 and moved toward the conveying belt 12 has a predetermined amount based on the gap between the conveying belt 12 and the coating roll 14 and the thickness of the substrate 2. It moves to the surface of the material 2 and a coating film is formed. At this time, the coating composition 20 that has not moved to the surface of the base material 2 moves to the second doctor blade 24 side with the rotation of the coating roll 14 while adhering to the surface of the coating roll 14. The second doctor blade 24 scrapes the surface of the coating roll 14.

Since the first doctor blade 22 and the second doctor blade 24 are provided in each of the doctor roll 16 and the coating roll 14, the doctor roll 16 does not move from the surface of the doctor roll 16 to the surface of the coating roll 14. The streaks of the coating composition 20 that remain streaks on the surface and the streaks of the coating composition 20 that remain streaks on the surface of the coating roll 14 without moving from the surface of the coating roll 14 to the surface of the substrate 2, It can be erased by the first doctor blade 22 and the second doctor blade 24, and as a result, the film thickness of the coating film of the coating composition 20 applied onto the substrate 2 can be made uniform.

(Coating roll)
As the coating roll 14, a rubber lining roll lined with rubber is usually used.
The surface hardness (JIS-A standard) of the coating roll 14 is preferably 10 to 70, more preferably 20 to 50. If the hardness is 10 or more, it is easy to control the film thickness of the coating film of the coating composition 20 applied on the substrate 2. If the hardness is 70 or less, even if a template glass is used as the substrate 2, the surface of the coating roll 14 can follow the irregularities on the surface of the template glass, and the coating film thickness of the coating composition 20 can be reduced. Easy to make uniform.

(Coating roll rotation speed)
When applying the coating composition on the substrate, the rotational speed (that is, the peripheral speed) of the coating roll 14 is made slower than the conveying speed of the substrate 2. By making the rotation speed of the coating roll 14 slower than the conveyance speed of the substrate 2, it is easy to form a low reflection film having an arbitrary film thickness that can be optically designed (that is, excellent in film thickness controllability). The rotation speed of the coating roll 14 is preferably 0.28 times or more of the transport speed of the base material 2 and 0.98 times or less of the transport speed of the base material 2 from the viewpoint of further excellent film thickness controllability. More preferably, it is 0.35 times or more of the transport speed of the base material 2 and 0.90 times or less of the transport speed of the base material 2.

In Patent Document 1, in order to make the film thickness uniform, the rotation speed of the coating roll 14 is made faster than the conveyance speed of the base material 2, but in the present invention, a specific coating composition described later is used. By using 20, even if the rotation speed of the coating roll 14 is slower than the conveying speed of the substrate 2, the film thickness of the coating film of the coating composition 20 applied onto the substrate 2 can be made uniform.

(Doctor roll)
As the doctor roll 16, a metal roll whose surface is made of metal or a rubber lining roll lined with rubber is usually used.
The doctor roll 16 preferably has a plurality of grooves formed on the surface from the viewpoint of easily holding the coating composition 20 on the surface of the doctor roll 16. From the viewpoint of making the film thickness uniform, it is more preferable that a lattice-like groove is formed on the surface.

(Indentation thickness)
The indentation thickness of the doctor roll 16 with respect to the coating roll 14 (this indentation thickness is the coating roll with respect to the tangent in the state where the coating roll 14 and the doctor roll 16 are not pushed by the doctor roll 16 when the coating roll 14 and the doctor roll 16 are disposed. The doctor roll is pushed in by a rubber lining on the surface of the roller), and is preferably 0.1 to 1.0 mm, more preferably 0.3 to 0.9 mm. If the indentation thickness is within this range, it is easy to make the film thickness of the coating composition 20 applied onto the substrate 2 uniform, and the coating film of the coating composition 20 applied onto the substrate 2. Easy to control the film thickness.

(gap)
The gap between the conveyor belt 12 and the coating roll 14 is appropriately adjusted according to the thickness of the base material 2, the film thickness of the coating composition 20 applied on the base material 2, and the like.

(Substrate transport speed)
The conveying speed of the substrate 2 is preferably 3 to 20 m / min, and more preferably 5 to 15 m / min. If the conveyance speed of the base material 2 is 3 m / min or more, the productivity is improved. If the conveyance speed of the base material 2 is 20 m / min or less, it is easy to control the film thickness of the coating film of the coating composition 20 applied on the base material 2.

(temperature)
The coating temperature (this coating temperature refers to the temperature of the substrate when applied to the substrate surface) is preferably room temperature to 80 ° C., more preferably room temperature to 60 ° C.
The drying or baking temperature of the coating film of the coating composition is preferably 30 ° C. or higher, and may be appropriately determined according to the material of the substrate 2, the fine particles (b) or the binder (c). For example, when the material of the base material 2, the fine particles (b) or the binder (c) is a resin, the drying or firing temperature is 30 ° C. or higher and the heat resistant temperature of the resin or lower, but this temperature is sufficient. An antireflection effect is obtained. When the base material 2 is glass, the firing temperature is preferably 30 ° C. or higher and 750 ° C. or lower. When the base material 2 is glass, the baking process of the low reflective film 3 and the physical strengthening process of glass can be combined. In the physical strengthening step, the glass is heated to near the softening temperature. In this case, the firing temperature is set in the range of about 600 ° C. to about 700 ° C. The firing temperature is usually preferably equal to or lower than the heat distortion temperature of the substrate 2. The lower limit of the firing temperature is determined according to the formulation of the coating composition 20. Since the polymerization proceeds to some extent even in natural drying, it is theoretically possible to set the drying or calcination temperature to a temperature setting near room temperature if there is no restriction on time.

(Coating composition)
The coating composition 20 includes a dispersion medium (a), fine particles (b) dispersed in the dispersion medium (a), and a binder (c) dissolved or dispersed in the dispersion medium (a). The terpene derivative (d) dissolved or dispersed in the dispersion medium (a) may be contained, and other additives may be further contained as necessary. The coating composition 20 includes, for example, mixing a fine particle (b) dispersion, a binder (c) solution, and an additional dispersion medium (a), a terpene derivative (d), and other additives as necessary. It is prepared by.

The viscosity of the coating composition 20 as the coating solution is 1.0 to 10.0 mPa · s, and preferably 2.0 to 5.0 mPa · s. If the viscosity of the coating composition 20 is 1.0 mPa · s or more, it is easy to control the film thickness of the coating film of the coating composition 20 applied on the substrate 2. If the viscosity of the coating composition 20 is 10.0 mPa · s or less, the drying or baking time and the coating time are shortened.
The viscosity of the coating composition 20 is measured with a B-type viscometer.

The solid content concentration of the coating composition 20 is preferably 1 to 9% by mass, and more preferably 2 to 6% by mass. If the solid content concentration is 1% by mass or more, the film thickness of the coating film of the coating composition 20 can be reduced, and the film thickness of the finally obtained low reflection film 3 can be made uniform. If solid content concentration is 9 mass% or less, it will be easy to make uniform the film thickness of the coating film of the coating composition 20 apply | coated on the base material 2. FIG.
The solid content of the coating composition 20 means the sum of the fine particles (b) and the binder (c) (however, in the case where the binder (c) is a hydrolyzate of alkoxysilane, the SiO ₂ equivalent solid content concentration).

The amount of the terpene derivative (d) is preferably 0.01 to 2 parts by mass, more preferably 0.03 to 1 part by mass with respect to 1 part by mass of the solid content of the coating composition 20. When the amount of the terpene derivative (d) is 0.01 parts by mass or more, the antireflection effect is sufficiently higher than that when the terpene derivative (d) is not added. When the terpene derivative (d) is 2 parts by mass or less, the strength of the low reflection film 3 is good.

The mass ratio of the fine particles (b) to the binder (c) (fine particles (b) / binder (c)) is preferably 10/90 to 95/5, more preferably 70/30 to 90/10. When the fine particles (b) / binder (c) is 95/5 or less, the adhesion between the low reflective film 3 and the substrate 2 is sufficiently high. When the fine particle (b) / binder (c) is 10/90 or more, the antireflection effect is sufficiently high.

(Dispersion medium (a))
Examples of the dispersion medium (a) (excluding the terpene derivative (d) described later) include water, alcohols (methanol, ethanol, isopropanol, butanol, diacetone alcohol, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl). Ketones), ethers (tetrahydrofuran, 1,4-dioxane, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), esters (methyl acetate, ethyl acetate, etc.), glycol ethers (ethylene glycol monoalkyl ether, etc.) And nitrogen-containing compounds (N, N-dimethylacetamide, N, N-dimethylformamide, N-methylpyrrolidone and the like), sulfur-containing compounds (dimethylsulfoxide and the like) and the like.

The dispersion medium (a) in the case where the binder (c) is an alkoxysilane hydrolyzate needs to contain water since water is required for hydrolysis of the alkoxysilane.
The dispersion medium (a) is preferably selected as appropriate according to the substrate 2 or the binder (c).
As the dispersion medium (a) when the substrate 2 is polycarbonate, an alcohol-based dispersion medium containing a solvent (for example, a nitrogen-containing compound) capable of dissolving the polycarbonate is preferable.
As the dispersion medium (a) when the substrate 2 is polyethylene terephthalate, an alcohol-based dispersion medium containing a solvent capable of dissolving polyethylene terephthalate (such as dichloromethane) is preferable.
When the substrate 2 is triacetyl cellulose, polyester, acrylic resin, silicone resin or the like is used as the binder (c), and as the dispersion medium (a) when the binder (c) is polyester, ethyl acetate or the like is used. Is preferred.

(Fine particles (b))
Examples of the fine particles (b) include at least one selected from the group consisting of metal oxide fine particles, metal fine particles, pigment-based fine particles, and resin fine particles.

As the material of the metal oxide fine particles, Al ₂ O ₃ , SiO ₂ , SnO ₂ , TiO ₂ , ZrO ₂ , ZnO, CeO ₂ , Sb-containing SnO _X (ATO), Sn-containing In ₂ O ₃ (ITO), and Suitable materials include at least one selected from the group consisting of RuO ₂ . Among these, SiO ₂ is suitable as a material for the low reflection film 3 because it has a low refractive index, and is particularly preferable.
Examples of the metal fine particle material include metals such as Ag and Ru, alloys such as AgPd and RuAu, and the like.
Examples of the pigment-based fine particles include inorganic pigments such as titanium black and carbon black, and organic pigments.
Examples of the resin fine particle material include polystyrene and melanin resin.

Examples of the shape of the fine particles (b) include a spherical shape, an elliptical shape, a needle shape, a plate shape, a rod shape, a conical shape, a cylindrical shape, a cubic shape, a rectangular shape, a diamond shape, a star shape, and an indefinite shape. The fine particles (b) may be hollow, perforated, or communicating holes. In addition, the fine particles (b) may be present in a state where each fine particle is independent, each fine particle may be linked in a chain shape, or each fine particle may be aggregated. As the fine particles (b), those having the above-mentioned shapes may be mixed.
The fine particles (b) may be used alone or in combination of two or more.

The average aggregate particle diameter of the fine particles (b) is preferably 1 to 1000 nm, more preferably 3 to 500 nm, and even more preferably 5 to 300 nm. When the average aggregate particle diameter of the fine particles (b) is 1 nm or more, the antireflection effect is sufficiently high. If the average aggregate particle diameter of the fine particles (b) is 1000 nm or less, the haze of the low reflective film 3 can be kept low.
The average aggregate particle diameter of the fine particles (b) is an average aggregate particle diameter of the fine particles (b) in the dispersion medium (a), and is measured by a dynamic light scattering method. In the case of monodispersed fine particles (b) in which no aggregation is observed, the average aggregate particle size is equal to the average primary particle size.

The low reflection film 3 in the present invention exhibits an antireflection effect by the voids selectively formed around the fine particles (b), and therefore the material of the fine particles (b) is not necessarily of a low refractive index (for example, SiO 2 ₂ ) need not be used. Therefore, it is possible to form the low reflection film 3 having both the various characteristics of the fine particles (b) and the antireflection effect. For example, when the material of the fine particles (b) is SiO ₂ , the refractive index of the low reflective film 3 can be further lowered, so that the low reflective film 3 having a sufficiently low reflectance can be formed. Further, when the material of the fine particles (b) is ATO, the low reflection film 3 having both conductivity and / or infrared shielding property and antireflection effect can be formed. Further, when the material of the fine particles (b) is CeO ₂ or ZnO, the low reflection film 3 having both the ultraviolet absorption and the antireflection effect can be formed. Further, even when the material of the fine particles (b) is TiO ₂ having a high refractive index, the low reflection film 3 can be formed with a single layer coating which has not been considered in the past. Therefore, the hydrophilic and antibacterial properties of TiO ₂ Thus, the low reflection film 3 having both properties and an antireflection effect can be formed. Further, when the material of the fine particles (b) is an organic pigment or an inorganic pigment, a colored low reflection film 3 can be formed, and a colored filter having an antireflection function can be manufactured.

(Binder (c))
Examples of the binder (c) include a hydrolyzate of alkoxysilane (sol-gel silica, that is, a silica precursor by a sol-gel method), a resin (for example, a thermoplastic resin, a thermosetting resin, or an ultraviolet curable resin). .
The binder (c) is preferably selected as appropriate according to the substrate 2.
As the binder (c) when the substrate 2 is glass, a hydrolyzate of alkoxysilane is preferable.

Examples of the alkoxysilane include tetraalkoxysilane (tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, etc.), alkoxysilane having a perfluoropolyether group (perfluoropolyether triethoxysilane, etc.), perfluoroalkyl. Group-containing alkoxysilane (perfluoroethyltriethoxysilane, etc.), vinyl group-containing alkoxysilane (vinyltrimethoxysilane, vinyltriethoxysilane, etc.), epoxy group-containing alkoxysilane (2- (3,4-epoxycyclohexyl), etc. ) Ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane), Alkoxysilanes (3-acryloyloxy propyl trimethoxysilane and the like) or the like having a acryloyloxy group.

In the case of tetraalkoxysilane, hydrolysis of the alkoxysilane is performed using water or an acid or alkali as a catalyst at least 4 times mol of alkoxysilane. Examples of the acid include inorganic acids (HNO ₃ , H ₂ SO ₄ , HCl, etc.) and organic acids (formic acid, oxalic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, etc.). Examples of the alkali include ammonia, sodium hydroxide, potassium hydroxide and the like. The catalyst is preferably an acid from the viewpoint of long-term storage, and the catalyst is preferably one that does not hinder the dispersion of the fine particles (b).

(Terpene derivative (d))
The terpene means a hydrocarbon having a composition of (C ₅ H ₈ ) _n (where n is an integer of 1 or more) having isoprene (C ₅ H ₈ ) as a structural unit. The terpene derivative means terpenes having a functional group derived from terpene. The terpene derivative (d) includes those having different degrees of unsaturation.

The terpene derivative (d) is preferably a terpene derivative having a hydroxyl group and / or a carbonyl group in the molecule from the viewpoint of the antireflection effect of the low reflective film 3, and the hydroxyl group, aldehyde group (—CHO), keto group in the molecule. A terpene derivative having at least one functional group selected from the group consisting of (—C (═O) —), an ester bond (—C (═O) O—), and a carboxy group (—COOH) is more preferable. More preferred are terpene derivatives having in the molecule at least one functional group selected from the group consisting of a hydroxyl group, an aldehyde group and a keto group.

Examples of the terpene derivative (d) include terpene alcohols (for example, α-terpineol, terpinene 4-ol, L-menthol, (±) citronellol, myrtenol, nerol, borneol, farnesol, phytol, etc.), terpene aldehyde (for example, citral) , Β-cyclocitral, perilaldehyde, etc.), terpene ketone (eg, (±) camphor, β-ionone, etc.), terpene carboxylic acid (eg, citronellic acid, abietic acid, etc.), terpene ester (eg, terpinyl acetate) , Menthyl acetate, etc.). In particular, terpene alcohol is preferable.
A terpene derivative (d) may be used individually by 1 type, and may use 2 or more types together.

(Other additives)
Examples of other additives include surfactants for improving leveling properties, and metal compounds for improving durability of the low reflective film 3.
Examples of the surfactant include silicone oil and acrylic.
As the metal compound, a zirconium chelate compound, a titanium chelate compound, an aluminum chelate compound and the like are preferable. Examples of the zirconium chelate compound include zirconium tetraacetylacetonate and zirconium tributoxy systemate.

(Function and effect)
In the method for producing an article with a low reflection film of the present invention described above, since the coating composition is applied as described above by the coating roll of the reverse roll coater, it can be applied to a wide substrate. Since the conveying speed of the material can be made relatively fast, the amount of coating composition required is relatively small.

Further, in the method for producing an article with a low reflection film of the present invention described above, the viscosity of the coating composition is 10 mPa · s or less, which is a relatively low viscosity, so the drying or baking time and coating time are compared. Short.

In the method for producing an article with a low reflection film of the present invention described above, a specific coating composition is used, and the rotation speed of the coating roll of the reverse roll coater is made slower than the conveyance speed of the substrate. Therefore, even if the viscosity of the coating composition is relatively low, it is possible to form a low reflection film having a uniform film thickness, and it is easy to form a low reflection film having an arbitrary film thickness that can be optically designed. . That is, the film thickness controllability is excellent.

In addition, since the coating composition described above includes the dispersion medium (a), the fine particles (b), and the binder (c) as described above, a low reflection having an antireflection effect by the reverse roll coater method. Films can be formed at low cost and at relatively low temperatures.
That is, when the low reflection film is formed by the reverse roll coating method unique to the present invention using the coating composition described above, voids are selectively formed around the fine particles (b) in the low reflection film. Improves the antireflection effect.
For example, when the film thickness is thick and non-uniform, the terpene is not volatilized uniformly during firing, and voids are not formed as intended. On the other hand, if the film thickness is thin and uniform, the terpene volatilizes efficiently and smoothly during firing, the portion where the terpene was present remains as a void, and the volume of the void increases, so the antireflection effect is increased.

In addition, the article with a low reflection film described above has a high antireflection effect because it has a high antireflection effect, can be produced at low cost, and has a coating film that can be formed even at a relatively low temperature. Furthermore, the base material that can be used when manufacturing the article is not so limited, and can be manufactured at a relatively low cost.

Hereinafter, the present invention will be described in more detail with reference to examples.
Examples 1 to 4 are examples, and examples 5 and 6 are comparative examples.

(Average primary particle size of fine particles)
The average primary particle diameter of the fine particles was calculated by converting from the specific surface area measured by the BET method and the volume of the spherical particles assuming that the spherical particles were uniformly dispersed in the carrier.

(Average aggregated particle size of fine particles)
The average aggregate particle size of the fine particles was measured using a dynamic light scattering particle size analyzer (manufactured by Nikkiso Co., Ltd., Microtrac UPA).

(viscosity)
The viscosity of the coating composition was measured using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., MODEL BL) after adjusting the liquid temperature to 25 ° C. in a thermostatic bath.

(Film thickness)
The film thickness of the low-reflection film is measured with a spectral reflectance film thickness meter (manufactured by Otsuka Electronics Co., Ltd., FE3000), and measured with a curve obtained from the dispersion formula of nk Couchy by the least square method. It was measured by fitting the reflected curve. Moreover, the film thickness of the low reflection film was measured at four locations, and the average value and the difference (variation) between the maximum value and the minimum value were determined.

(Transmittance)
The transmittance of the article with a low reflection film was determined by measuring the transmittance of light at a wavelength of 400 nm to 1100 nm using a spectrophotometer (manufactured by JASCO Corporation, V670).
The transmittance difference was determined based on the following formula (1).
Transmittance difference = transmittance of article with low reflection film−transmittance of base material only (1).

(Reflectance)
A black vinyl tape was affixed to the surface of the substrate opposite to the low reflection film so as not to contain bubbles, and then the reflectance of the 100 mm × 100 mm low reflection film at the center of the substrate was measured. . The reflectance is the bottom reflectance in the wavelength range of 300 to 1200 nm (that is, the lowest value in the wavelength range of 300 to 1200 nm). When the wavelength indicating the bottom reflectance was 380 nm or less or 780 nm or more, a spectrophotometer (manufactured by JASCO Corporation, V670) was used. When the wavelength indicating the bottom reflectance was 380 to 780 nm, a spectrophotometer (Otsuka Electronics Co., Ltd., instantaneous multi-photometry system MCPD-3000) was used.

(Abrasion resistance)
Attach a felt (manufactured by Shin-Kurika Kogyo Co., Ltd., polishing puff AM-1) to a rubbing tester (manufactured by Ohira Rika Kogyo Co., Ltd.). The transmittance of the article with a low reflection film after the measurement was measured in the same manner as the transmittance measurement method.
The change in transmittance was determined based on the following equation (2).
Change in transmittance = transmittance of article with low reflection film before abrasion resistance test−transmittance of article with low reflection film after abrasion resistance test (2).

(appearance)
The appearance of the low reflective film of the article with the low reflective film was visually observed and evaluated according to the following criteria.
○: There is no unevenness or streaks in the film and it is uniform.
Δ: Some unevenness and streaks can be confirmed.
X: Many irregularities and streaks can be confirmed.

(Preparation of binder solution (c-1))
While stirring 77.6 g of denatured ethanol (manufactured by Nippon Alcohol Sales Co., Ltd., Solmix AP-11, a mixed solvent mainly composed of ethanol, the same shall apply hereinafter), 11.9 g of ion-exchanged water and 61% by mass of nitric acid were added thereto. A mixed solution with 0.1 g was added and stirred for 5 minutes. Thereto, tetraethoxysilane (SiO ₂ in terms of solid concentration: 29 wt%) 10.4 g was added and stirred for 30 minutes at room temperature, SiO ₂ in terms of solid content concentration of 3.0 mass% of binder solution (c- 1) was prepared.
Incidentally, SiO ₂ in terms of solid concentration is a solid content concentration when all Si of tetraethoxysilane was converted to SiO _2.

(Preparation of binder solution (c-2))
While stirring 80.4 g of denatured ethanol (manufactured by Nippon Alcohol Sales Co., Ltd., Solmix AP-11, a mixed solvent mainly composed of ethanol, the same applies hereinafter), 11.9 g of ion-exchanged water and 61% by mass of nitric acid A mixed solution with 0.1 g was added and stirred for 5 minutes. Thereto, tetraethoxysilane (SiO ₂ in terms of solid concentration: 29 wt%) 7.6 g was added and stirred for 30 minutes at room temperature, SiO ₂ in terms of solid content concentration of 2.2 mass% of binder solution (c- 2) was prepared.

(Linear SiO ₂ fine particle dispersion (b-1))
Product name: “Snowtex OUP” manufactured by Nissan Chemical Industries, Ltd., solid content concentration in terms of SiO ₂ : 15.5% by mass, average primary particle size: 10 to 20 nm, average aggregated particle size: 40 to 100 nm.

(Preparation of coating composition (A))
While stirring 24.5 g of denatured ethanol, 24.0 g of isobutyl alcohol, 20.0 g of binder solution (c-1), and 15.5 g of chain SiO ₂ fine particle dispersion (b-1) were added thereto. In addition, 15.0 g of diacetone alcohol (hereinafter referred to as DAA) and 1.0 g of α-terpineol which is a terpene derivative (d) were added, and a coating composition (A ) Was prepared. The composition and viscosity are shown in Table 1.

(Preparation of coating compositions (B) and (C))
Coating compositions (B) and (C) were prepared in the same manner as the coating composition (A) except that the formulation shown in Table 1 was changed. The composition and viscosity are shown in Table 1.

[Example 1]
Template glass (made by Asahi Glass Co., Ltd., trade name: “Solite” (template glass with a low iron content and high permeability soda lime glass (white plate glass), with a satin pattern on the surface), size : 100 mm x 100 mm, thickness: 3.2 mm), polishing and washing the textured surface of the template glass with an aqueous cerium oxide dispersion, rinsing the cerium oxide with water, rinsing with ion-exchanged water, and drying I let you.

The above template glass is preheated in a preheating furnace (VTR-115, manufactured by ISUZU), and the reverse roll coater is applied to the satin pattern surface on the template glass in a state where the glass surface temperature of the template glass is kept at 30 ° C. The coating composition (A) was applied with a coating roll (manufactured by Sanwa Seiki Co., Ltd.). The application conditions were as follows.
Substrate transport speed: 13.8 m / min,
Rotating speed of coating roll: 9.0 m / min
Doctor roll rotation speed: 9.0 m / min,
Gap between coating roll and conveyor belt: 2.9 mm,
Indentation thickness between coating roll and doctor roll: 0.6 mm.
As the coating roll, a rubber lining roll lined with a rubber (ethylene propylene diene rubber) having a surface hardness (JIS-A standard) of 30 was used. As the doctor roll, a metal roll having lattice-like grooves formed on the surface thereof was used.
Thereafter, it was baked in the atmosphere at 500 ° C. for 30 minutes to obtain an article on which a low reflective film was formed. The article was evaluated. The results are shown in Table 2.

[Examples 2 to 5]
An article on which a low reflection film was formed was obtained in the same manner as in Example 1 except that the coating composition and application conditions were changed to the coating composition and application conditions shown in Table 2. The article was evaluated. The results are shown in Table 2.

[Example 6]
A template glass kept at 30 ° C. by a preheating furnace is set on a stand in a booth where a spray coating robot (manufactured by Kawasaki Robotics Co., Ltd., JE005F) is installed, and a paint composition ( X) was applied. Thereafter, it was baked in the atmosphere at 500 ° C. for 30 minutes to obtain an article on which a low reflective film was formed. The article was evaluated. The results are shown in Table 2.

In Example 1, it can be seen that the low reflection film having the target film thickness is formed, the film thickness variation of the low reflection film is small, and the uniformity is good. Moreover, although the conveyance speed was changed in Example 2 and Example 3 and the rotation speed was also changed, a uniform film was obtained in the same manner. Also, a uniform film was obtained in the same manner as in Example 4 in which the ratio of the fine particles to the binder was changed.
In Example 5, since the rotation speed of the coating roll was made faster than the conveying speed of the substrate, a low reflection film having a target film thickness could not be obtained.
In Example 6, since the low reflection film was formed by the spray coating method, the variation in the film thickness of the low reflection film became large.

An article with a low reflection film obtained by the production method of the present invention is an article having an antireflection function for the purpose of reducing external light reflection or improving light transmittance, for example, a cover glass of a solar cell, a display (LCD, PDP, organic EL, CRT, SED, etc.), their front plates, vehicle (car, train, aircraft, etc.) window glass, residential window glass, touch panel cover glass, etc.
The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2011-219241 filed on October 3, 2011 are incorporated herein as the disclosure of the present invention. .

DESCRIPTION OF SYMBOLS 1 Article with a low reflection film 2 Base material 3 Low reflection film 4 Base material body 5 Functional layer 10 Reverse roll coater 12 Conveying belt 14 Coating roll 16 Doctor roll 18 Backup roll 20 Coating composition 22 First doctor blade 24 Second Doctor blade

Claims

A method for producing an article having a low reflective film on a substrate,
The method includes a step of applying the coating composition by a coating roll of a reverse roll coater to form the low reflection film on the substrate conveyed in a predetermined direction,
The coating composition includes a dispersion medium (a), fine particles (b) dispersed in the dispersion medium (a), and a binder (c) dissolved or dispersed in the dispersion medium (a), and Using a coating solution having a viscosity of 1.0 to 10.0 mPa · s,
A method for producing an article with a low reflection film, wherein a rotation speed of the coating roll when applying the coating composition on a substrate in the step is slower than a conveyance speed of the substrate.
The method for producing an article with a low reflection film according to claim 1, wherein the coating composition further comprises a terpene derivative (d) dissolved or dispersed in the dispersion medium (a).
The method for producing an article with a low reflection film according to claim 2, wherein the amount of the terpene derivative (d) is 0.01 to 2 parts by mass with respect to 1 part by mass of the solid content of the coating composition.
The method for producing an article with a low reflection film according to any one of claims 1 to 3, wherein the solid content concentration of the coating composition is 1 to 9% by mass.
The mass ratio of the fine particles (b) to the binder (c) (fine particles (b) / binder (c)) is 10/90 to 95/5. Of manufacturing an article with a low reflection film.
The method for producing an article with a low reflection film according to any one of Claims 1 to 5, wherein a conveying speed of the substrate is 3 to 20 m / min.
The article with a low reflection film according to any one of claims 1 to 6, wherein a rotation speed of the coating roll is 0.28 times or more and 0.98 times or less of a conveyance speed of the base material. Production method.
The method for producing an article with a low reflection film according to any one of claims 1 to 7, wherein the surface hardness (JIS-A standard) of the coating roll is 10 to 70.
The method for producing an article with a low reflection film according to any one of claims 1 to 8, wherein the base material is a template glass having a satin pattern formed on at least one surface thereof.