WO2013172460A1

WO2013172460A1 - Manufacturing method for optical film

Info

Publication number: WO2013172460A1
Application number: PCT/JP2013/063847
Authority: WO
Inventors: 戸田　義朗; 千葉　隆人
Original assignee: コニカミノルタ株式会社
Priority date: 2012-05-18
Filing date: 2013-05-17
Publication date: 2013-11-21
Also published as: JPWO2013172460A1; JP6020558B2

Abstract

[Problem] An optical film manufacturing method is provided which is able to hold down variations in film thickness in an optical function layer, even when the optical function layer is nanometers thin. [Solution] The manufacturing method is for optical film in which at least one optical function layer with a thickness from 1 to 1,000 nm has been formed on a substrate. This manufacturing method includes a step (1) in which an application liquid containing a high polymer is shear-processed at a shearing velocity equal to or greater than 1,000 (1/s), and a step (2) in which the application liquid obtained in step (1) is applied to a substrate to form a coating film.

Description

Manufacturing method of optical film

The present invention relates to a method for producing an optical film.

An optical film is a film that can transmit or reflect and absorb light, and can exhibit optical functions such as refraction, birefringence, antireflection, wide viewing angle, light diffusion, and brightness improvement.

Optical films include liquid crystal displays (LCD) and plasma as infrared shielding films, antireflection films, alignment films, polarizing films, polarizing plate protective films, retardation films, viewing angle widening films, brightness enhancement films, and electromagnetic shielding films. It is used for flat panel displays (FPD) such as displays (PDP), window glass of buildings and vehicles, and the like.

For example, Patent Document 1 discloses a substrate made of polyester as an optical film used for a liquid crystal display, a plasma display, an organic EL display, a surface electric field (SED) display, and a CRT display, and on at least one surface of the substrate. Formed on the easy-adhesion layer having a refractive index of more than 1.70 and not more than 1.85 and a thickness of 50 to 100 nm, and a refractive index of 1.40 or more. 1. An optical laminated film characterized by comprising a protective layer having a thickness of 1.60 or less and a thickness of 3 nm to 10 nm. According to the optical laminated film of Patent Document 1, by having an easy-adhesion layer and a protective layer having a predetermined refractive index and thickness, the scratch resistance can be improved, and the occurrence of powder falling and scratches can be suppressed. It is described that unevenness can be eliminated.

JP 2008-183882 A

In recent years, it has been demanded to reduce the thickness of an optical film used, in particular, an optical functional layer constituting the optical film (for example, to a thickness of nano order). Various effects can be obtained by thinning the optical film. For example, thinning the antireflection film of the antireflection film can increase the definition of the flat panel display. Moreover, infrared light can be efficiently shielded by thinning the refractive index layer of the infrared shielding film.

In the optical film described in Patent Document 1, the easy adhesion layer and the protective layer (optical functional layer) have a nano-order thickness. According to Patent Document 1, an optical functional layer having a nano-order thickness is manufactured by a so-called wet film forming method in which a coating liquid is applied to a substrate and then dried to form an optical functional layer. However, the optical functional layer manufactured by the wet film forming method may have variations in film thickness within the optical functional layer, and as a result, color unevenness may occur in the optical film and the appearance may deteriorate. found.

Therefore, an object of the present invention is to provide means capable of suppressing the occurrence of variations in film thickness in the optical functional layer even when the optical functional layer is thinned to the nano order.

As a result of intensive studies, the present inventors have found that when an optical functional layer is formed by a wet film-forming method, using a sheared coating liquid, even if the optical functional layer is thinned on the nano order. The inventors have found that the occurrence of film thickness variation in the optical functional layer can be suppressed, and have completed the present invention.

That is, the above-described problem of the present invention is achieved by the following means.

1. A method for producing an optical film in which at least one optical functional layer having a film thickness of 1 to 1000 nm is formed on a substrate, wherein the coating liquid containing a polymer has a shear rate of 1000 (1 / s) or more. A manufacturing method comprising: (1) applying a shearing process of (2); and (2) forming a coating film by applying the coating liquid obtained in the step (1) on a substrate;
2. 2. The manufacturing method according to 1, wherein the coating is performed at a speed of 1 m / min or more;
3. The production method according to 1 or 2, wherein the step (2) is performed within 3 hours after the step (1);
4). 4. The production method according to any one of 1 to 3, wherein the shearing treatment is performed by a dispersing device, a high-speed stirring device, a discharging device, or a combination thereof.

It is a schematic diagram of the milder which is one form of a dispersing device. It is a schematic diagram of the pressure type homogenizer which is one form of a dispersing device. It is a schematic diagram of the circumscribed gear pump which is one form of the discharge device. It is a schematic diagram of the general purpose stirring apparatus which is one form of a high-speed stirring apparatus.

One embodiment of the present invention relates to a method for producing an optical film in which at least one optical functional layer having a film thickness of 1 to 1000 nm is formed on a substrate. In the production method, the coating solution containing a polymer is subjected to a step (1) of applying a shearing treatment at a shear rate of 1000 (1 / sec) or more, and the coating solution obtained in the step (1) is coated on a substrate. And a step (2) of forming a coating film.

According to the present invention, even when the optical functional layer is thinned to the nano order, a means that can suppress the occurrence of variations in the film thickness in the optical functional layer is provided.

<Optical film>
The optical film manufactured by the manufacturing method according to this embodiment is formed by forming at least one optical functional layer having a film thickness of 1 to 1000 nm on a substrate. The method for producing the optical film includes a step (1) of applying a shearing treatment having a shear rate of 1000 (1 / sec) or more to a coating solution containing a polymer, and a coating solution obtained in the step (1) as a base material. And a step (2) of forming a coating film by coating on the top.

The optical film has different functions depending on the composition and configuration of the optical functional layer. Therefore, the technical idea according to the present invention is various optical films, for example, an infrared shielding film, an antireflection film, an alignment film, a polarizing film, a polarizing plate protective film, a retardation film, by appropriately considering known matters. It can be used for a film, a viewing angle widening film, a brightness enhancement film, an electromagnetic wave shielding film, and the like. In the following description, an infrared shielding film in which refractive index layers having different refractive indexes are laminated will be described, but the present invention is not limited thereto. The infrared shielding film corresponds to an optical film, and the refractive index layer corresponds to an optical functional layer.

In general, in an infrared shielding film, it is preferable to design a large difference in refractive index between adjacent refractive index layers from the viewpoint that the infrared reflectance can be increased with a small number of layers. In this embodiment, at least one of the refractive index differences between adjacent refractive index layers is preferably 0.1 or more, more preferably 0.3 or more, and particularly preferably 0.4 or more. Moreover, it is preferable that all the refractive index differences between the laminated refractive index layers are within the preferable range. However, even in this case, the outermost layer and the lowermost layer among the refractive index layers constituting the reflective layer may have a configuration outside the above preferred range.

The reflectance in a specific wavelength region is determined by the difference in refractive index between two adjacent layers and the number of layers, and the larger the difference in refractive index, the same reflectance can be obtained with a smaller number of layers. The refractive index difference and the required number of layers can be calculated using commercially available optical design software. For example, in order to obtain an infrared reflectance of 90% or more, if the refractive index difference is smaller than 0.1, it is necessary to stack 100 layers or more. In such cases, productivity loss, increased scattering at the stack interface, reduced transparency, and manufacturing failures can occur.

Furthermore, as an optical characteristic of the infrared shielding film of this embodiment, the transmittance in the visible light region shown in JIS R3106-1998 is preferably 50% or more, preferably 75% or more, more preferably 85% or more. In addition, it is preferable that the region having a wavelength of 900 nm to 1400 nm has a region with a reflectance exceeding 50%.

The infrared shielding film has a configuration in which a refractive index layer is laminated, so that at least one infrared light is irradiated when infrared light is irradiated from the base material side or from the laminated refractive index layer side. The part can be shielded to exhibit an infrared shielding effect.

In one embodiment, the stacked refractive index layers are formed by alternately stacking high refractive index layers and low refractive index layers. The laminated high refractive index layer and low refractive index layer may be the same or different. Whether the refractive index layer is a high refractive index layer or a low refractive index layer is determined by comparing the refractive index with the adjacent refractive index layer. Specifically, when a refractive index layer is used as a reference layer, if the refractive index layer adjacent to the reference layer has a lower refractive index than the reference layer, the reference layer is a high refractive index layer (the adjacent layer is a low refractive index layer). It is judged to be a rate layer. On the other hand, if the refractive index of the adjacent layer is higher than that of the reference layer, it is determined that the reference layer is a low refractive index layer (the adjacent layer is a high refractive index layer).

As described above, whether the layer is a high refractive index layer or a low refractive index layer is a relative one determined by the relationship with the adjacent refractive index layer, but the refractive index (nH) of the high refractive index layer is 1. It is preferably .60 to 2.50, more preferably 1.70 to 2.50, further preferably 1.80 to 2.20, and 1.90 to 2.20. Is particularly preferred. On the other hand, the refractive index (nL) of the low refractive index layer is preferably 1.10 to 1.60, more preferably 1.30 to 1.55, and more preferably 1.30 to 1.50. More preferably. In addition, the value measured as follows shall be employ | adopted for the value of the refractive index of each refractive index layer. Specifically, a sample is prepared by cutting a coating film obtained by applying a refractive index layer to be measured as a single layer on a support to a size of 10 cm × 10 cm. In order to prevent reflection of light on the back surface of the sample, the surface opposite to the measurement surface (back surface) is roughened and light-absorbed with black spray. Using the spectrophotometer U-4000 type (manufactured by Hitachi, Ltd.), the sample thus prepared was measured for 25 points of reflectance in the visible region (400 nm to 700 nm) under the condition of regular reflection at 5 degrees. An average value is obtained, and an average refractive index is obtained from the measurement result.

The range of the total number of refractive index layers is preferably 200 or less, more preferably 100 or less, and even more preferably 50 or less from the viewpoint of productivity.

The thickness of the refractive index layer per layer is 1 to 1000 nm, preferably 20 to 800 nm, more preferably 50 to 350 nm.

<Step (1)>
Step (1) is a step of applying a shearing treatment with a shear rate of 1000 (1 / sec) or more to a coating solution containing a polymer.

In the production of an infrared shielding film, usually, at least two kinds of coating liquids, ie, a coating liquid for a high refractive index layer and a coating liquid for a low refractive index layer are prepared as coating liquids.

[Composition of coating solution]
The coating solution contains a polymer. Furthermore, a solvent, a crosslinking agent, metal oxide particles, an emulsion resin, and other additives may be included as necessary.

(High molecular)
The polymer that can be used is not particularly limited, and examples thereof include water-soluble polymers. The water-soluble polymer is not particularly limited, and examples thereof include a polymer having a reactive functional group, modified polyvinyl alcohol, gelatin, and thickening polysaccharide. In this specification, “water-soluble polymer” means a G2 glass filter (maximum) when dissolved in water so that the concentration of 0.5% by mass is obtained at the temperature at which the water-soluble polymer is most dissolved. It means that the mass of the insoluble matter that is filtered off when filtering through pores of 40 to 50 μm is within 50 mass% of the added water-soluble polymer.

Polymers having reactive functional groups Examples of polymers having reactive functional groups used in the present invention include unmodified polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymers, potassium acrylate- Acrylic resins such as acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, or acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid -Styrene acrylic resins such as acrylate copolymer, styrene-α-methylstyrene-acrylic acid copolymer, or styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer, styrene-styrenesulfonic acid Sodium copolymerization Styrene-2-hydroxyethyl acrylate copolymer, styrene-2-hydroxyethyl acrylate-potassium styrene sulfonate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinylnaphthalene-acrylic acid Copolymers, vinyl naphthalene-maleic acid copolymers, vinyl acetate-maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-based copolymers such as vinyl acetate-acrylic acid copolymers, and the like Of the salt. Among these, it is preferable to use unmodified polyvinyl alcohols, polyvinyl pyrrolidones, and copolymers thereof.

The form of the copolymer when the polymer having the reactive functional group is a copolymer may be any of a block copolymer, a random copolymer, a graft copolymer, and an alternating copolymer. Good.

Modified Polyvinyl Alcohol The modified polyvinyl alcohol used in the present invention is one obtained by subjecting unmodified polyvinyl alcohol to one or more arbitrary modification treatments. Examples thereof include amine-modified polyvinyl alcohol, ethylene-modified polyvinyl alcohol, carboxylic acid-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, thiol-modified polyvinyl alcohol, and acetal-modified polyvinyl alcohol. As these modified polyvinyl alcohols, commercially available products may be used, or those produced by methods known in the art may be used.

Further, modified polyvinyl alcohols such as polyvinyl alcohol having a cation-modified terminal, anion-modified polyvinyl alcohol having an anionic group, and nonion-modified polyvinyl alcohol may also be used.

Examples of the cation-modified polyvinyl alcohol include primary to tertiary amino groups and quaternary ammonium groups as described in JP-A-61-10383 in the main chain or side chain of the polyvinyl alcohol. It can be obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl) ammonium chloride. N-vinylimidazole, N-vinyl-2-methylimidazole, N- (3-dimethylaminopropyl) methacrylamide, hydroxyethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1, And 1-dimethyl-3-dimethylaminopropyl) acrylamide. The ratio of the ethylenically unsaturated monomer having a cationic group in the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, relative to vinyl acetate.

Examples of the anion-modified polyvinyl alcohol include polyvinyl alcohol having an anionic group as described in JP-A-1-206088, JP-A-61-237681 and JP-A-63-307979. Examples thereof include a copolymer of vinyl alcohol and a vinyl compound having a water-soluble group, and a modified polyvinyl alcohol having a water-soluble group as described in JP-A-7-285265.

Nonionic modified polyvinyl alcohol includes, for example, a polyvinyl alcohol derivative in which a polyalkylene oxide group as described in JP-A-7-9758 is added to a part of vinyl alcohol, and JP-A-8-25795. The block copolymer of the vinyl compound and vinyl alcohol which have the described hydrophobic group is mentioned.

Among the above-mentioned modified polyvinyl alcohols, (1) one or more selected from the group consisting of unmodified polyvinyl alcohol having an average degree of polymerization of 200 or more and 2400 or less, and (2) unsaturated carboxylic acid and salts and esters thereof. It is preferable to use a copolymer (graft copolymer) obtained by copolymerizing with a polymerizable vinyl monomer.

In the case where the modified polyvinyl alcohol is the above graft copolymer, the above-mentioned various modified polyvinyl alcohols are used as the unmodified polyvinyl alcohol having an average degree of polymerization of 200 or more and 2400 or less constituting the graft copolymer (1). May be.

The unmodified polyvinyl alcohol used as the raw material for the modified polyvinyl alcohol has an average degree of polymerization of about 200 to 2400, preferably an average degree of polymerization of about 900 to 2400, and more preferably an average degree of polymerization of about 1300 to 1700. The degree of saponification of unmodified polyvinyl alcohol is preferably about 60 to 100 mol%, more preferably 78 to 96 mol%. Such a saponified polyvinyl alcohol can be produced by radical polymerization of vinyl acetate and appropriately saponifying the obtained polyvinyl acetate. In order to produce a desired unmodified polyvinyl alcohol, The polymerization degree and saponification degree are controlled by a method known per se.

In addition, as such a partially saponified polyvinyl alcohol, it is possible to use a commercially available product. Examples of preferable commercially available unmodified polyvinyl alcohol include Gohsenol EG05, EG25 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), PVA203 ( Manufactured by Kuraray Co., Ltd.), PVA204 (manufactured by Kuraray Co., Ltd.), PVA205 (manufactured by Kuraray Co., Ltd.), JP-04 (manufactured by Nihon Vinegar & Poval Co., Ltd.), JP-05 (manufactured by Nihon Venture & Poval Co., Ltd.) Is mentioned. In addition, not only one kind of unmodified polyvinyl alcohol is used alone as a raw material for the modified polyvinyl alcohol, but also two or more kinds of unmodified polyvinyl alcohols having different degrees of polymerization and saponification may be appropriately used in accordance with the purpose. Can do. For example, unmodified polyvinyl alcohol having an average polymerization degree of 300 and unmodified polyvinyl alcohol having an average polymerization degree of 1500 can be mixed and used.

Examples of the polymerizable vinyl monomer that is polymerized with the raw unmodified (modified) polyvinyl alcohol include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, or salts thereof (for example, Alkali metal salts, ammonium salts, alkylamine salts), esters thereof (eg, substituted or unsubstituted alkyl esters, cyclic alkyl esters, polyalkylene glycol esters), unsaturated nitriles, unsaturated amides, aromatic vinyls , Aliphatic vinyls, unsaturated bond-containing heterocycles, and the like. Specifically, (a) acrylic acid esters include, for example, methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, hydroxyethyl acrylate, polyethylene glycol acrylate (polyethylene glycol and acrylic acid Ester) and polypropylene glycol acrylate (ester of polypropylene glycol and acrylic acid). (B) Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, and 2-ethylhexyl. Methacrylate, hydroxyethyl methacrylate, polyethylene glycol Tacrylate (ester of polyethylene glycol and methacrylic acid), etc. (c) Unsaturated nitriles such as acrylonitrile, methacrylonitrile, etc. (d) Unsaturated amides such as acrylamide, dimethylacrylamide, methacrylamide (E) aromatic vinyls such as styrene and α-methylstyrene, (f) aliphatic vinyls such as vinyl acetate, and (g) unsaturated bond-containing heterocycles such as N -Vinylpyrrolidone, acryloylmorpholine and the like are exemplified.

The above-mentioned modified polyvinyl alcohol can be produced by modifying unmodified polyvinyl alcohol or a derivative thereof by a method known per se.

In particular, examples of the method for producing the graft copolymer as the modified polyvinyl alcohol include methods known per se such as radical polymerization, for example, solution polymerization, suspension polymerization, emulsion polymerization and bulk polymerization. It can be carried out under normal polymerization conditions. This polymerization reaction is usually performed in the presence of a polymerization initiator, if necessary, as a reducing agent (for example, sodium erythorbate, sodium metabisulfite, ascorbic acid), a chain transfer agent (for example, 2-mercaptoethanol, α-methylstyrene). Dimer, 2-ethylhexylthioglycolate, lauryl mercaptan) or a dispersant (for example, a surfactant such as sorbitan ester or lauryl alcohol), water, an organic solvent (for example, methanol, ethanol, cellosolve, carbitol) or the like In a mixture of Moreover, the removal method of an unreacted monomer, drying, a grinding | pulverization method, etc. may be well-known methods, and there is no restriction | limiting in particular.

Gelatin As the gelatin used in the present invention, various gelatins which have been widely used in the field of silver halide photographic materials can be exemplified. For example, in addition to acid-treated gelatin and alkali-treated gelatin, enzyme-treated gelatin and gelatin derivatives that undergo enzyme treatment in the gelatin production process, that is, amino, imino, hydroxy, or carboxy groups as functional groups in the molecule It may be modified by treating with a reagent having a group obtained by reacting with it. The general method for producing gelatin is well known and is described, for example, in T.W. H. James: The Theory of Photographic Process 4th. ed. Reference can be made to descriptions such as 1977 (Macmillan), p. 55, Science Photo Handbook (above), p. 72-75 (Maruzen Co., Ltd.), Photographic Engineering Basics-Silver Salt Photography, p. 119-124 (Corona). . Also, Research Disclosure Magazine Vol. 176, No. The gelatin described in IX page of 17643 (December, 1978) can be mentioned.

Thickening polysaccharide There is no restriction | limiting in particular as thickening polysaccharide used by this invention, For example, generally known natural simple polysaccharide, natural complex polysaccharide, synthetic simple polysaccharide, synthetic complex polysaccharide, etc. are mentioned. be able to. For details of these thickening polysaccharides, reference can be made to “Biochemical Dictionary (2nd edition)” (Tokyo Kagaku Dojin), “Food Industry”, Vol. 31 (1988), p.

The thickening polysaccharide is a polymer of saccharides and has a large number of hydrogen bonding groups in the molecule. Due to the difference in hydrogen bonding strength between molecules depending on the temperature, the viscosity at low temperature and the viscosity at high temperature are different. It is a polysaccharide with the characteristic that the difference is large, and when metal oxide particles or polyvalent metal compounds are added, the metal oxide particles or polyvalent metals react with the metal oxide particles or polyvalent metal compounds at low temperatures. It forms a hydrogen bond or ionic bond with the compound, causing an increase in viscosity or gelation. The increase in viscosity is preferably 1.0 mPa · s or more at 15 ° C. compared to the viscosity at 15 ° C. before the addition of the metal oxide particles or the polyvalent metal compound. The viscosity increase width is more preferably 5.0 mPa · s or more, and further preferably 10.0 mPa · s or more. In this specification, a value measured with a Brookfield viscometer is adopted as the viscosity.

More specific examples of thickening polysaccharides applicable to the present invention include, for example, pectin, galactan (eg, agarose, agaropectin, etc.), galactomannoglycan (eg, locust bean gum, guaran, etc.), xyloglucan, etc. (Eg, tamarind gum, tamarind seed gum, etc.), glucomannoglycan (eg, salmon mannan, wood-derived glucomannan, xanthan gum, etc.), galactoglucomannoglycan (eg, softwood-derived glycan), arabinogalactoglycan ( For example, soybean-derived glycan, microorganism-derived glycan, etc.), glucoraminoglycan (eg, gellan gum), glycosaminoglycan (eg, hyaluronic acid, keratan sulfate, etc.), alginic acid and alginate, agar, κ-carrageenan, λ -Carrageenan, Examples thereof include natural polymer polysaccharides derived from red algae such as ι-carrageenan and furseleran, and celluloses such as carboxymethyl cellulose (cellulose carboxymethyl ether), carboxyethyl cellulose, methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. From the viewpoint of not reducing the dispersion stability of the metal oxide particles that can coexist in the coating solution, those in which the structural unit does not have a carboxylic acid group or a sulfonic acid group are preferable. Such polysaccharides include, for example, pentoses such as L-arabitose, D-ribose, 2-deoxyribose, and D-xylose, and hexoses such as D-glucose, D-fructose, D-mannose, and D-galactose only. It is preferable that it is a polysaccharide. Specifically, tamarind seed gum known as xyloglucan whose main chain is glucose and side chain is glucose, guar gum known as galactomannan whose main chain is mannose and side chain is glucose, cationized guar gum, Hydroxypropyl guar gum, locust bean gum, tara gum, and arabinogalactan whose main chain is galactose and whose side chain is arabinose can be preferably used.

The above polymers may be used alone or in combination of two or more.

In addition, the mass average molecular weight of the polymer is preferably 1000 or more, more preferably 5000 to 1000000, and still more preferably 10,000 to 100,000. In this specification, the mass average molecular weight is a gel permeation chromatography (GPC) analyzer using a TSKgel GMHxL, TSKgel G4000HxL or TSKgel G2000HxL (Tosoh Corporation) column (solvent: tetrahydrofuran (THF)). ) Means the molecular weight expressed in terms of polystyrene by differential refractometer detection.

The concentration of the polymer in the coating solution is preferably 0.01 to 20% by mass, and more preferably 0.1 to 10% by mass. It is preferable for the concentration of the polymer to be in the above range since the coating solution has a certain viscosity and can be advantageous for film formation.

(solvent)
The solvent that can be used in the present invention is not particularly limited, and examples thereof include water, an organic solvent, or a mixed solvent thereof.

Examples of the organic solvent include alcohols such as methanol, ethanol, 2-propanol, and 1-butanol; esters such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; diethyl ether; Examples include ethers such as propylene glycol monomethyl ether and ethylene glycol monoethyl ether; amides such as dimethylformamide and N-methylpyrrolidone; ketones such as acetone, methyl ethyl ketone, acetylacetone and cyclohexanone. These organic solvents may be used alone or in admixture of two or more. From the viewpoint of environment and simplicity of operation, the solvent of the coating solution is preferably water or a mixed solvent of water and methanol, ethanol, or ethyl acetate, and more preferably water.

(Crosslinking agent)
The crosslinking agent has a function of curing the polymer. By curing, water resistance can be imparted to the refractive index layer.

The crosslinking agent that can be used is not particularly limited as long as it causes a curing reaction with a polymer. For example, when the polymer is unmodified polyvinyl alcohol or modified polyvinyl alcohol, boric acid and its salt (oxygen acid and its salt centered on a boron atom), specifically, orthoboric acid and diboric acid , Metaboric acid, tetraboric acid, pentaboric acid, and octaboric acid or salts thereof are preferably used. Boric acid and its salt may be used alone or in admixture of two or more, and it is particularly preferable to use a mixed aqueous solution of boric acid and borax. Other known compounds can also be used, and are generally compounds having a group capable of reacting with a polymer, or compounds that promote the reaction between different groups of a resin. It is appropriately selected and used accordingly. Specific examples of the crosslinking agent include, for example, diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl-4- Epoxy crosslinking agents such as glycidyloxyaniline, sorbitol polyglycidyl ether, glyceryl polyglycidyl ether; aldehyde crosslinking agents such as formaldehyde and glycoxal; 2,4-dichloro-4-hydroxy-1,3,5- Examples include active halogen-based crosslinking agents such as S-triazine; 1.3.5-active vinyl compounds such as tris-acryloyl-hexahydro-S-triazine and bisvinylsulfonylmethyl ether; and aluminum alum.

When gelatin is used as the resin, as the crosslinking agent, for example, organic compounds such as vinylsulfone compounds, urea-formalin condensates, melanin-formalin condensates, epoxy compounds, aziridine compounds, active olefins, isocyanate compounds, etc. Hardeners, inorganic polyvalent metal salts such as chromium, aluminum and zirconium may be used.

The concentration of the crosslinking agent in the coating solution is preferably 0.001 to 20% by mass, and more preferably 0.01 to 10% by mass. When the cross-linking agent is in the above range, the coating solution has a certain spinnability and viscosity, which is advantageous for film formation, and the formed refractive index layer can have suitable water resistance.

(Metal oxide particles)
The metal oxide particles which can be used is not particularly limited, titanium oxide _(TiO 2), zinc oxide (ZnO), zirconium oxide _(ZrO 2), niobium oxide _(Nb _{2 O} 5), aluminum oxide _(Al 2 O ₃ ), silicon oxide (SiO ₂ ), calcium fluoride (CaF ₂ ), magnesium fluoride (MgF ₂ ), indium tin oxide (ITO), antimony tin oxide (ATO), and the like. Of these, titanium oxide (TiO ₂ ) is preferably used for the high refractive index layer coating solution, and silicon oxide (SiO ₂ ) is preferably used for the low refractive index layer coating solution.

As the titanium oxide (TiO ₂ ), it is particularly preferable to use a rutile type titanium oxide having a high refractive index and low catalytic activity. If the catalytic activity is low, side reactions (photocatalytic reactions) that occur in the refractive index layer and adjacent layers can be suppressed, and the weather resistance can be increased.

As the titanium oxide, a water-based titanium oxide sol having a pH of 1.0 to 3.0 and having a positive zeta potential of titanium particles is hydrophobized so that it can be dispersed in an organic solvent. preferable. Examples of the method for preparing the aqueous titanium oxide sol include Japanese Patent Laid-Open Nos. 63-17221, 7-819, 9-165218, 11-43327, and 63. Reference can be made to the matters described in JP-A-17221, JP-A-7-819, JP-A-9-165218, JP-A-11-43327, and the like.

As for other methods for producing titanium oxide particles, for example, the method described in “Titanium oxide—physical properties and applied technology” (Kagino Kiyono, p. 255-258 (2000) Gihodo Publishing Co., Ltd.), or WO 2007/039953 The method of step (2) described in paragraphs “0011” to “0023” of the document can be referred to. The production method according to the step (2) is a step of treating titanium dioxide hydrate with at least one basic compound selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides. The titanium dioxide dispersion obtained in (1) is treated with a carboxylic acid group-containing compound and an inorganic acid. In the present invention, an aqueous sol of titanium oxide having a pH adjusted to 1.0 to 3.0 with an inorganic acid in the step (2) can be used.

Examples of the silicon oxide (SiO ₂ ) include synthetic amorphous silica and colloidal silica. Among these, it is more preferable to use an acidic colloidal silica sol, and it is more preferable to use a colloidal silica sol dispersed in water and / or an organic solvent. The colloidal silica can be obtained by heating and aging a silica sol obtained by metathesis with an acid of sodium silicate or the like and passing through an ion exchange resin layer. Such colloidal silica is disclosed in, for example, JP-A-57-14091, JP-A-60-219083, JP-A-60-218904, JP-A-61-20792, JP-A-61- No. 188183, No. 63-17807, No. 4-93284, No. 5-278324, No. 6-92011, No. 6-183134, No. 6-297830 No. 7-81214, No. 7-101142, No. 7-179029, No. 7-137431, pamphlet of International Publication No. 94/26530, etc. . Colloidal silica may be a synthetic product or a commercially available product.

The metal oxide particles may be used alone or in combination of two or more.

The average particle diameter of the metal oxide particles is preferably 2 to 100 nm, more preferably 3 to 50 nm, and further preferably 4 to 30 nm. The average particle size of the metal oxide particles is determined by observing the particles themselves or the particles appearing on the cross section or surface of the refractive index layer with an electron microscope, measuring the particle size of 1000 arbitrary particles, and calculating the simple average value ( (Number average). Here, the particle diameter of each particle is represented by a diameter assuming a circle equal to the projected area.

The concentration of the metal oxide particles in the coating solution is preferably 20 to 70% by mass and more preferably 30 to 70% by mass with respect to 100% by mass of the solid content of the refractive index layer. It is preferable that the content of the metal oxide particles is 20% by mass or more because a desired refractive index can be obtained. Further, it is preferable that the content of the metal oxide particles is 70% by mass or less because flexibility of the film can be obtained and film formation becomes easy.

In addition, when both refractive index layers having different refractive indexes (for example, a high refractive index layer and a low refractive index layer) include metal oxide particles, anionization treatment or cationization treatment is performed, and the metal oxide particles It is preferable to have the same ionicity (charge). By performing anionization treatment or cationization treatment, a repulsive force is generated between the two types of metal oxide particles. For example, when a refractive index layer is formed by multilayer coating, aggregation at the layer interface, etc. Can be difficult to occur.

As an anionization treatment of metal oxide particles, for example, anion treatment of titanium oxide is exemplified. The titanium oxide particles can be anionized by coating with a silicon-containing hydrated oxide. The coating amount of the silicon-containing hydrated compound is usually 3 to 30% by mass, preferably 3 to 10% by mass, and more preferably 3 to 8% by mass. When the coating amount is 30% by mass or less, a desired refractive index of the high refractive index layer can be obtained, and when the coating amount is 3% or more, particles can be stably formed.

The cationization treatment of the metal oxide particles can be performed by using, for example, a cationic compound. Examples of the cationic compound include a cationic polymer and a polyvalent metal salt, and a polyvalent metal salt is preferred from the viewpoint of adsorption power and transparency. Examples of polyvalent metal salts include aluminum, calcium, magnesium, zinc, iron, strontium, barium, nickel, copper, scandium, gallium, indium, titanium, zirconium, tin, lead, and other metal hydrochlorides, sulfates, nitrates, Examples include acetate, formate, succinate, malonate, chloroacetate and the like. Of these, water-soluble aluminum compounds, water-soluble calcium compounds, water-soluble magnesium compounds, water-soluble zinc compounds, and water-soluble zirconium compounds are preferably used, and water-soluble aluminum compounds and water-soluble zirconium compounds are more preferably used. Specific examples of the water-soluble aluminum compound include polyaluminum chloride (basic aluminum chloride), aluminum sulfate, basic aluminum sulfate, aluminum potassium sulfate (alum), ammonium aluminum sulfate (ammonium alum), sodium aluminum sulfate, aluminum nitrate, Examples thereof include aluminum phosphate, aluminum carbonate, polysulfuric acid aluminum silicate, aluminum acetate, and basic aluminum lactate. The coating amount of the cationic compound varies depending on the shape and particle size of the metal oxide particles, but is preferably 1% by mass to 15% by mass with respect to the metal oxide particles.

(Emulsion resin)
The emulsion resin is usually a polymer dispersed in a coating solution. The emulsion resins can be fused to each other at the time of application in the step (2) described later. The emulsion resin is obtained by emulsion polymerization of an oil-soluble monomer using a polymer dispersant or the like.

Oil-soluble monomers that can be used are not particularly limited, but ethylene, propylene, butadiene, vinyl acetate and its partial hydrolyzate, vinyl ether, acrylic acid and its esters, methacrylic acid and its esters, acrylamide and its derivatives, Examples thereof include methacrylamide and derivatives thereof, styrene, divinylbenzene, vinyl chloride, vinylidene chloride, maleic acid, vinyl pyrrolidone and the like. Of these, acrylic acid, its esters, and vinyl acetate are preferably used from the viewpoint of transparency and particle size.

As acrylic acid and / or its esters and vinyl acetate emulsion, commercially available ones may be used. For example, Acryt UW-309, UW-319SX, UW-520 (manufactured by Taisei Fine Chemical Co., Ltd.), and Mobile vinyl (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and the like.

Further, the dispersant that can be used is not particularly limited, but in addition to a low-molecular dispersant such as alkyl sulfonate, alkylbenzene sulfonate, diethylamine, ethylenediamine, and quaternary ammonium salt, polyoxyethylene nonylphenyl is used. Examples thereof include polymer dispersants such as ether, polyethylene ethylene laurate, hydroxyethyl cellulose, and polyvinyl pyrrolidone.

The above-mentioned emulsion preferably has a glass transition temperature (Tg) of 20 ° C. or lower, more preferably −30 to 10 ° C. from the viewpoint of enhancing flexibility.

(Other additives)
Other additives applicable to the refractive index layer according to the present invention are listed below. For example, ultraviolet absorbers, anionic, cationic or nonionic surfactants described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, sulfuric acid, PH adjusters such as phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide and potassium carbonate, antifoaming agents, lubricants such as diethylene glycol, preservatives, antifungal agents, antistatic agents, matting agents, antioxidants And various known additives such as additives, flame retardants, infrared absorbers, dyes and pigments.

[Preparation process of coating solution]
The method for preparing the coating solution is not particularly limited, and examples thereof include a method in which a polymer and, if necessary, an additive such as a crosslinking agent and metal oxide particles are added to a solvent and mixed by stirring. At this time, the order of addition of the respective components is not particularly limited, and the respective components may be sequentially added and mixed while stirring, or may be added and mixed at one time while stirring.

In the coating solution, the polymer may interact with each other between the molecules and within the molecule, such as bonds due to end groups, bonds in the cross-linking agent, and entanglement between the molecules. The size is getting bigger. Since the increase in the apparent molecular size varies depending on the presence or absence of the interaction and the degree thereof, various polymers having different apparent molecular sizes are mixed in the coating solution. When the coating liquid is applied onto the substrate in such a state, a coating film is formed without the coating liquid being stretched to a uniform thickness when the coating liquid contacts the substrate. As a result, the thickness of the refractive index layer varies. Such a variation in film thickness becomes more prominent when the refractive index layer is formed on the nano order.

The polymer interaction is such that when the mass average molecular weight of the polymer in the coating solution is 1000 or more, and when the coating solution contains 0.01% by mass or more of the polymer, the cross-linking agent is added to the coating solution in an amount of 0.1%. This may occur particularly when it is contained in an amount of 001% by mass or more, and when the coating liquid contains a solid substance (for example, particles) accompanied by a binding reaction with a polymer.

Therefore, in this embodiment, a shearing treatment is applied to the coating solution at a shear rate of 1000 (1 / sec) or more, preferably 5000 to 10000000 (1 / sec), more preferably 10,000 to 1000000 (1 / sec). By applying a shearing treatment at a shear rate of 1000 (1 / sec) or more to the coating solution, the interaction generated in the polymer can be eliminated. As a result, it is considered that the apparent molecular size of the polymer present in the coating solution takes an approximate value. By coating such a coating solution on the substrate, a coating film having a uniform film thickness can be formed.

In this specification, “shear treatment” means that the coating liquid is treated at a predetermined shear rate. More specifically, this means that the coating liquid is moved at a predetermined speed in a flow path or the like having a predetermined gap to apply a shearing force to the coating liquid. By the shearing treatment, at least a part of the interaction generated in the polymer can be eliminated. Here, in this specification, the “shear rate” is calculated by the following formula (1).

“Minimum gap” means the smallest gap to which a shearing force is applied in the flow path through which the coating liquid moves. The “speed” refers to the moving speed of the coating solution when the coating solution passes through the minimum gap. At this time, when the coating liquid is moved at a constant speed, the highest shearing force is applied when passing through the minimum gap.

In this embodiment, the shearing treatment may be performed by any method as long as the shear rate to the coating solution is 1000 (1 / sec) or more. The shearing process can be performed by, for example, a dispersion device, a discharge device, and a high-speed stirring device.

Dispersing device As the dispersing device, a milder, a pressure type homogenizer, a high-speed rotational shearing type homogenizer, or the like can be used. Hereinafter, the shearing process in the case of using a milder and a pressure type homogenizer will be described in detail.

FIG. 1 is a schematic diagram of a milder that is one form of a dispersing device. The milder in FIG. 1 has a stator tooth 1 that is a fixed tooth and a rotor tooth 2 that is a rotating tooth. The coating liquid 4 moving in the gap (shear gap) La between the stator teeth 1 and the rotor teeth 2 generates a velocity gradient (shear velocity) in the radial direction of the rotor teeth 2. Due to the velocity gradient, an internal frictional force (shearing force) is generated between the stator teeth 1 and the rotor teeth 2. Since the polymer in the coating solution 4 passes through the shear gap La while receiving a shearing force, the molecular structure of the polymer is broken and the molecules are oriented in the flow direction, resulting in elimination of the interaction that occurs in the polymer. sell. In FIG. 1, the shear gap La corresponds to the “minimum gap” in the equation (1), and the speed of the coating liquid 4 when moving through the shear gap La, which is the minimum gap, corresponds to the “speed” in the equation (1). . In addition, since the introduction of the coating liquid 5 into the shear gap 3 is performed in the radial direction from the slit gap of the rotor tooth 2, the coating liquid 4 flowing into the shear gap La and the introduced coating liquid 5 are continuously provided. The collision is repeated. That is, according to the milder in FIG. 1, shearing and mixing are continuously performed on the coating solution.

In the milder, the minimum gap between the stator teeth and the rotor teeth in the shear gap is preferably 0.05 to 0.5 mm, and more preferably 0.1 to 0.3 mm. Further, the rotational speed of the rotor teeth is preferably 1 to 500 m / s, and more preferably 3 to 300 m / s. The shear rate can be adjusted by appropriately setting the minimum gap between the stator teeth and the rotor teeth in the shear gap and the rotational speed of the rotor teeth.

As the above-mentioned milder, for example, Ebara Milder (manufactured by Ebara Manufacturing Co., Ltd.), Milder (manufactured by Taiheiyo Kiko Co., Ltd.) or the like can be used.

FIG. 2 is a schematic diagram of a pressure homogenizer that is one form of a dispersing device. The pressure homogenizer of FIG. 2 has a valve seat 11 and a valve 12. The coating liquid 14 supplied by a pressurizing mechanism (not shown) moves between the valve seats 11 at high pressure and at high speed. When the coating liquid passes through the narrow gap Lb between the valve seat 11 and the valve 12, the liquid between the coating liquid that has collided with the varibe 12 and changed the flow direction and the coating liquid that is about to pass through the gap Lb. It is considered that friction between the two occurs, and as a result, a large shearing force is generated in the coating solution. This shear force is proportional to the minimum gap Lb. In FIG. 2, the gap Lb is the minimum gap to which a shearing force is applied, and corresponds to the “minimum gap” in Equation (1). Further, the speed of the coating liquid 14 when moving through the gap Lb, which is the minimum gap, corresponds to the “speed” in Expression (1).

In the pressure homogenizer, the distance between the valve seat and the valve is preferably 0.05 to 0.5 mm, and more preferably 0.1 to 0.3 mm. The speed when passing between the valve seat and the valve is preferably 1 to 500 m / s, more preferably 3 to 300 m / s. The shear rate can be adjusted by appropriately setting the distance between the valve seat and the valve, the supply condition of the coating liquid in the pressurizing mechanism, and the like.

As the pressure homogenizer as described above, for example, a pressure homogenizer LAB1000 (manufactured by SMT Co., Ltd.) or the like can be used.

The high-speed rotation shearing homogenizer has a configuration similar to that of a milder, and is a processing device that performs a shearing process between a rotor that rotates at a high speed and a stator that is adjacent via a narrow gap. When the coating liquid flows by the rotor rotating at high speed, the interaction between the polymers can be eliminated in the same manner as described above by the shear generated by the velocity gradient generated between the stator and the collision between the coating liquids. Conceivable.

Examples of the high-speed rotational shearing type homogenizer include TK Robomix (Primics Co., Ltd.), Claremix CLM-0.8S (M Technique Co., Ltd.), and Homogenizer (Microtech Nichion Co., Ltd.). Can be used.

Discharge device As the discharge device, a rotary pump such as a Kia pump, a Mono pump, or a rotary pump can be used. Hereinafter, the shearing process when the gear pump is used will be described in detail.

FIG. 3 is a schematic diagram of a circumscribed gear pump which is one form of the discharge device. The circumscribed gear pump of FIG. 3 has a gear 22a and a gear 22b. The gear 22a and the gear 22b rotate while the teeth are engaged at the center. The coating liquid 24 is separated by the

gears

22 a and 22 b and moves in the gap Lc between the

gear

22 a or 22 b and the outer box 21. At this time, a speed gradient (shear speed) is generated in the coating liquid 24 that moves between the moving

gear

22a or 22b and the fixed outer box 21, thereby generating a shearing force. In FIG. 3, the gap Lc corresponds to the “minimum gap” in the equation (1), and the speed of the coating liquid 24 when moving through the gap Lc, which is the minimum gap, corresponds to the “speed” in the equation (1).

In the circumscribed gear pump, the distance between the gear and the outer box is preferably 1 to 10 mm, and more preferably 1 to 5 mm. Further, the speed at the time of passing through the gear and the outer box is preferably 1 to 10 m / s, and more preferably 2 to 10 m / s. The shear rate can be adjusted by appropriately setting the distance between the gear and the outer box, the rotational speed of the gear, and the like.

In addition to the external gear pump shown in FIG. 3, an internal gear pump using an external gear and an internal gear may be used. The inscribed gear pump can be used more suitably because the minimum gap becomes smaller.

As the gear pump as described above, for example, a chemical gear pump GX-25S (manufactured by Iwaki Co., Ltd.) or the like can be used.

High-speed stirrer As the high-speed stirrer, a high-speed rotating general-purpose stirrer, a closed-type high-speed stirrer that is also used in a dispersing device, and the like can be used. Hereinafter, the shearing process in the case of using a high-speed rotation type general-purpose stirring device will be described in detail.

FIG. 4 is a schematic diagram of a general-purpose stirring device which is one form of a high-speed stirring device. The general-purpose stirring device in FIG. 4 has a stirring blade 32. As the stirring blade 32 rotates, the coating liquid 34 supplied into the processing chamber is stirred. At this time, the coating liquid 34 collides with the inner wall 31 of the processing chamber by the stirring of the stirring blade 32, and then moves along the inner wall 31. This creates a shear force. Therefore, since the speed of the coating liquid when colliding with the inner wall 31 corresponds to the rotational speed of the stirring blade 32, the gap Ld between the tip of the stirring blade 32 and the inner wall 31 is the “minimum gap” in the equation (1). The rotational speed of the stirring blade 32 corresponds to the “speed” in the equation (1). Note that the general-purpose agitator simultaneously applies the shearing force and simultaneously mixes the coating liquid 34, and the coating liquid 34 is continuously sheared and mixed.

In the general-purpose stirring device, the distance between the tip of the stirring blade and the inner wall of the processing chamber is preferably 1 to 10 mm, and more preferably 1 to 5 mm. The rotation speed of the stirring blade is preferably 1 to 10 m / s, and more preferably 2 to 10 m / s. The shear rate can be adjusted by appropriately setting the distance between the tip of the stirring blade and the inner wall of the processing chamber, the rotational speed of the stirring blade, and the like.

As the above-mentioned general-purpose stirring device, for example, a three-one motor LB series (manufactured by Shinto Kagaku Co., Ltd.), a super mixer (manufactured by Satake Chemical Machinery Co., Ltd.), or the like can be used.

The temperature of the shearing treatment varies depending on the numerical value of the shear rate and the kind and content of the polymer in the coating solution, but is preferably 20 to 70 ° C., and is preferably 25 to 60 ° C. This is preferable from the viewpoint of load and work safety.

The shearing time varies depending on the value of the shear rate, the type and content of the polymer in the coating solution, and is not particularly limited. However, from the viewpoint of continuous processing and productivity, 0.01 to 10 minutes is preferable, and 0.01 to 2 minutes is more preferable.

The viscosity of the coating solution obtained by the shearing treatment varies depending on the temperature of the coating solution and the type of the coating solution, but is preferably 1 to 2000 mPa · s, and more preferably 1 to 1000 mPa · s. . When the viscosity of the coating liquid is in the above range, the coating liquid has high coating properties, and the occurrence of film thickness variation can be suppressed. In addition, since the viscosity of a coating liquid receives to the influence of the interaction which may arise in a polymer | macromolecule, the viscosity of a coating liquid can be adjusted with a shearing process.

The interaction of the polymer eliminated by the shearing process in the step (1) may return to the original with time due to the property of the polymer. When the interaction occurs again, various polymers having different apparent molecular weights are mixed in the coating solution, and the film thickness may vary. Therefore, it is preferable to perform step (2) described later immediately after step (1). More specifically, the time until the step (2) after the step (1) varies depending on the type of the coating liquid and the conditions in which the coating liquid is stagnated, but is preferably within 3 hours. It is more preferably within 1 hour, and further preferably within 30 minutes.

<Step (2)>
Step (2) is a step of forming a coating film by applying the coating liquid obtained in step (1) on a substrate.

[Base material]
The substrate applied to the optical film of the present invention is not particularly limited as long as it is transparent, and a known resin film can be used. Specifically, polyethylene (PE), polypropylene (PP), polystyrene (PS), polyarylate, polymethyl methacrylate, polyamide, polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate. Examples include phthalate (PEN), polysulfone, polyethersulfone, polyetheretherketone, polyimide, aromatic polyamide, and polyetherimide. Of these, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), and the like are preferably used from the viewpoints of cost and availability.

The substrate using the resin film may be an unstretched film or a stretched film, but in the case of a resin film having crystallinity such as PET or PEN, the strength is improved. From the viewpoint of suppressing thermal expansion, a film that is heat-set after stretching is preferred.

The base material using the resin film can be manufactured by a conventionally known general method. For example, an unstretched film that is substantially amorphous and not oriented can be produced by melting a resin as a material with an extruder, extruding it with an annular die or a T-die, and quenching. Further, the unstretched film is subjected to a known method such as uniaxial stretching, tenter-type sequential biaxial stretching, tenter-type simultaneous biaxial stretching, tubular-type simultaneous biaxial stretching, and the resin film flow (vertical axis) direction, and / or Alternatively, a stretched film can be produced by stretching in the direction perpendicular to the flow direction of the resin film (horizontal axis). The draw ratio in this case can be appropriately selected according to the resin as the raw material of the base material, but is preferably 2 to 10 times in the vertical axis direction and the horizontal axis direction.

The thickness of the substrate according to the present invention is preferably 5 to 300 μm, more preferably 15 to 150 μm. Moreover, the base material may be a laminate of two or more, and in this case, the type of the base material may be the same or different.

In addition, the base material may be subjected to relaxation treatment and off-line heat treatment from the viewpoint of dimensional stability. It is preferable that the relaxation treatment is performed in the process from the heat setting in the stretching process of the resin film to the winding in the transversely stretched tenter or after exiting the tenter. The relaxation treatment is preferably carried out at a treatment temperature of 80 to 200 ° C., more preferably 100 to 180 ° C. Further, in both the longitudinal direction and the width direction, the relaxation rate is preferably processed to 0.1 to 10%, more preferably 2 to 6%. The relaxed base material is further subjected to off-line heat treatment to improve heat resistance and further improve dimensional stability.

The substrate is preferably provided with an undercoat layer on one side or both sides during the film forming process. The undercoat layer can be formed in-line or after film formation. Examples of the method for forming the undercoat layer include a method of applying an undercoat layer coating solution and drying the obtained coating film. The undercoat layer coating solution usually contains a resin. Examples of the resin include polyester resins, acrylic-modified polyester resins, polyurethane resins, acrylic resins, vinyl resins, vinylidene chloride resins, polyethyleneimine vinylidene resins, polystyrene butadiene resins, polyethyleneimine resins, polyvinyl alcohol, and gelatin. . A known additive may be further added to the undercoat layer coating solution. The coating amount of the undercoat layer coating solution is preferably applied so as to be about 0.01 to 2 g / m ^{2 in} a dry state. The coating method of the undercoat layer coating solution is not particularly limited, and known methods such as a roll coating method, a gravure coating method, a knife coating method, a dip coating method, and a spray coating method can be used. The obtained coating film may be stretched, and usually an undercoat layer can be formed by drying at 80 to 120 ° C. while performing lateral stretching in a tenter after coating the coating solution. The undercoat layer may have a single layer structure or a laminated structure.

The substrate according to the present invention further includes a conductive layer, an antistatic layer, a gas barrier layer, an easy adhesion layer (adhesion layer), an antifouling layer, a deodorant layer, a droplet layer, an easy slip layer, a hard coat layer, and wear resistance. May have a known functional layer such as an adhesive layer, an adhesive layer, and an interlayer film layer.

When the base material has an intermediate layer such as the undercoat layer or the functional layer described above, the total film thickness of the base material and the intermediate layer is preferably 5 to 500 μm, more preferably 25 to 250 μm. preferable.

[Coating process]
In the coating step, the coating liquid obtained in step (1) is applied to the substrate to form a coating film.

The coating method of the coating liquid is not particularly limited, and for example, roll coating method, rod bar coating method, air knife coating method, spray coating method, curtain coating method, or US Pat. No. 2,761,419, US The slide bead coating method using the hopper described in Japanese Patent No. 2,761,791 and the extrusion coating method are preferably used.

The viscosity of a suitable coating solution varies depending on the coating method. For example, when the coating method is simultaneous multi-layer coating using a slide bead coating method, the viscosity of the coating solution may be 1 to 2000 mPa · s. It is preferably 1 to 1000 mPa · s.

The coating temperature is not particularly limited, but is preferably 20 to 60 ° C. A coating temperature of 20 ° C. or lower is preferable because a facility for cooling the coating solution is not necessary and costs can be reduced. On the other hand, it is preferable that the coating temperature is 60 ° C. or lower because a facility for heating the coating liquid becomes unnecessary, costs can be reduced, and work safety can be improved.

The coating speed is not particularly limited, but is preferably 1 m / min or more, more preferably 1 to 500 m / min. A coating speed of 1 m / min or more is preferable because high productivity can be obtained.

Application of the coating temperature in consideration of the coating temperature and the coating speed makes it possible to obtain a refractive index layer in which variations in film thickness are suppressed.

[Drying process]
A refractive index layer can be formed by drying the coating film obtained in the step (2).

The drying method is not particularly limited, and may be performed by a known method. Examples of the drying method include natural drying, heat drying, a method of applying hot air, a method of applying cold air, and the like. From the viewpoint of rapid drying, it is preferable to perform drying by heat drying. In this case, the heating temperature is preferably 15 to 120 ° C., more preferably 20 to 90 ° C., although it varies depending on the composition of the formed coating film.

<Step (3)>
The production method according to the present invention may further include a step of cooling the coating film obtained in the step (2) once before drying (hereinafter also referred to as step (3)). By performing the step (3), the surface of the refractive index layer (the interface in the case of being laminated) can be made more uniform.

Since the coating film immediately after coating has a low viscosity, for example, when the coating film immediately after coating is dried by applying hot air, the surface of the obtained refractive index layer may vary in thickness due to the hot air. In addition, when multilayer coating is performed, coating film components move between coating films, and the boundary between the obtained refractive index layers can be ambiguous. However, once the obtained coating film is cooled, the viscosity of the coating film increases rapidly, and the coating film can be stabilized. As a result, it is possible to suppress the occurrence of film thickness variation due to drying of hot air or the like and the movement of coating film components between coating films. However, since the performance of the infrared shielding film may differ depending on the movement of the coating component between the coating films, whether or not to perform the step (3) is appropriately determined according to the desired performance of the infrared shielding film. Can be determined.

When performing the step (3), it is preferable to use a polymer whose viscosity is easily increased by cooling the coating film as a component of the coating solution. As described above, the interaction of the polymer can be caused by bonding between end groups in the polymer and within the molecule, bonding in the cross-linking agent, entanglement between the molecules, and the like. Therefore, in order to more effectively demonstrate the effect of the step (3), it is preferable to use a polymer having a large number of functional groups or a polymer having a large molecular weight as a component of the coating solution and including a crosslinking agent. .

The cooling temperature in step (3) varies depending on the coating solution used, but is preferably −20 to 20 ° C., more preferably −5 to 10 ° C.

<Application>
The infrared shielding film obtained above can be applied to a wide range of fields. For example, pasting to facilities exposed to sunlight for a long time, such as outdoor windows of buildings and automobile windows, films for window pasting such as infrared shielding films that give an infrared shielding effect, films for agricultural greenhouses, etc. As, it is mainly used for the purpose of improving the weather resistance.

In particular, the infrared shielding film can be suitably applied to a member in which the infrared shielding film according to the present invention is bonded to a substrate such as glass or a glass substitute resin directly or via an adhesive.

That is, according to still another embodiment of the present invention, there is also provided an infrared shielding body in which the above infrared shielding film is provided on at least one surface of a substrate.

Specific examples of the substrate include, for example, glass, polycarbonate resin, polysulfone resin, acrylic resin, polyolefin resin, polyether resin, polyester resin, polyamide resin, polysulfide resin, unsaturated polyester resin, epoxy resin, melamine resin, Examples thereof include phenol resin, diallyl phthalate resin, polyimide resin, urethane resin, polyvinyl acetate resin, polyvinyl alcohol resin, styrene resin, vinyl chloride resin, metal plate, ceramic and the like. The type of the resin may be any of a thermoplastic resin, a thermosetting resin, and an ionizing radiation curable resin, and two or more of these may be used in combination. The substrate that can be used in the present invention can be produced by a known method such as extrusion molding, calendar molding, injection molding, hollow molding, compression molding and the like. The thickness of the substrate is not particularly limited, but is usually 0.1 mm to 5 cm.

The adhesive layer or adhesive layer that bonds the infrared shielding film and the substrate is preferably provided with the infrared shielding film on the sunlight (heat ray) incident surface side. In addition, it is preferable to sandwich the infrared shielding film according to the present invention between a window glass and a substrate because it can be sealed from surrounding gas such as moisture and has excellent durability. Even if the infrared shielding film according to the present invention is installed outdoors or outside a car (for external application), it is preferable because of environmental durability.

As the adhesive applicable to the present invention, an adhesive mainly composed of a photocurable or thermosetting resin can be used.

The adhesive preferably has durability against ultraviolet rays, and is preferably an acrylic adhesive or a silicone adhesive. Furthermore, an acrylic adhesive is preferable from the viewpoint of adhesive properties and cost. In particular, a solvent system is preferable in the acrylic pressure-sensitive adhesive because the peel strength can be easily controlled. When a solution polymerization polymer is used as the acrylic solvent-based pressure-sensitive adhesive, known monomers can be used as the monomer.

Further, a polyvinyl butyral resin or an ethylene-vinyl acetate copolymer resin used as an intermediate layer of laminated glass may be used. Specifically, plastic polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., Mitsubishi Monsanto Co., Ltd.), ethylene-vinyl acetate copolymer (manufactured by DuPont, Takeda Pharmaceutical Co., Ltd., duramin), modified ethylene-vinyl acetate copolymer (Mersen G, manufactured by Tosoh Corporation). In addition, you may add and mix | blend an ultraviolet absorber, an antioxidant, an antistatic agent, a heat stabilizer, a lubricant, a filler, coloring, an adhesion regulator etc. suitably in an adhesion layer.

Insulation performance and solar heat shielding performance of infrared shielding films or infrared shields are generally JIS R 3209 (multi-layer glass), JIS R 3106 (obtain transmittance, reflectance, emissivity, and solar heat of plate glass) Rate test method), and a method based on JIS R 3107 (calculation method of thermal resistance of plate glass and heat transmissivity in architecture).

Measure solar transmittance, solar reflectance, emissivity, and visible light transmittance. (1) Using a spectrophotometer with a wavelength (300 to 2500 nm), measure the spectral transmittance and spectral reflectance of various single glass plates. The emissivity is measured using a spectrophotometer having a wavelength of 5.5 to 50 μm. In addition, a predetermined value is used for the emissivity of float plate glass, polished plate glass, mold plate glass, and heat ray absorbing plate glass. (2) The solar transmittance, solar reflectance, solar absorption rate, and modified emissivity are calculated according to JIS R 3106 by calculating the solar transmittance, solar reflectance, solar absorption rate, and vertical emissivity. The corrected emissivity is obtained by multiplying the vertical emissivity by the coefficient shown in JIS R 3107. The heat insulation and solar heat shielding properties are calculated by (1) calculating the thermal resistance of the multilayer glass according to JIS R 3209 using the measured thickness value and the corrected emissivity. However, when the hollow layer exceeds 2 mm, the gas thermal conductance of the hollow layer is determined according to JIS R 3107. (2) The heat insulation is obtained by adding a heat transfer resistance to the heat resistance of the double-glazed glass and calculating the heat flow resistance. (3) The solar heat shielding property is calculated by obtaining the solar heat acquisition rate according to JIS R 3106 and subtracting it from 1.

Further, since the infrared shielding film obtained above is thinned, it may be applied to the surface of the display panel. For example, in a plasma display panel, an infrared shielding film can be bonded to a highly transparent PET film and introduced into a display screen. This shields infrared rays radiated from the plasma display panel, which can contribute to protection of the human body, prevention of malfunction between electronic devices, prevention of malfunction of the remote control, and the like.

[Production of infrared shielding film]
Example 1
Process (1)
Preparation of coating solution for low refractive index layer Colloidal silica (Snowtex OXS, manufactured by Nissan Chemical Industries, Ltd., solid content 10% by mass) 2400 parts by mass, 5% by mass polyvinyl alcohol (PVA-103, degree of polymerization 300, degree of saponification) 98.5 mol%, manufactured by Kuraray Co., Ltd.) 400 parts by weight of an aqueous solution and 1500 parts by weight of an aqueous 3% by weight boric acid solution, respectively, and then heated to 45 ° C. and stirred, 5% by weight polyvinyl alcohol (PVA-117, Polymerization degree 1700, saponification degree 98.5 mol%, manufactured by Kuraray Co., Ltd.) 4000 parts by mass aqueous solution, 1% by mass surfactant (Lapisol A30, manufactured by NOF Corporation) aqueous solution 100 parts by mass, pure water 1600 parts by mass Was added to prepare 10,000 parts by mass of a coating solution for a low refractive index layer.

Preparation of coating solution for high refractive index layer 15.0 mass% titanium oxide sol (SRD-W, volume average particle diameter 5 nm, rutile titanium dioxide particles, manufactured by Sakai Chemical Industry Co., Ltd.) 5000 mass parts pure water 20000 mass parts After the addition, it was heated to 90 ° C. Subsequently, 13000 parts by mass of an aqueous silicic acid solution (sodium silicate 4 (manufactured by Nippon Kagaku Kogyo Co., Ltd.) diluted with pure water so that the SiO ₂ concentration becomes 2.0% by mass) was gradually added, and the autoclave Medium, heat treatment was performed at 175 ° C. for 18 hours. After cooling, the mixture was concentrated with an ultrafiltration membrane to obtain a titanium dioxide sol (hereinafter, anion-treated titanium dioxide sol) on which SiO ₂ having a solid content concentration of 20% by mass was adhered.

200 parts by mass of 5 mass% polyvinyl alcohol (PVA-103, polymerization degree 300, saponification degree 98.5 mol%, manufactured by Kuraray Co., Ltd.) in 3000 parts by mass of the anion-treated titanium dioxide sol (solid content 20.0 mass%) 1 part by weight, 1000 parts by weight of a 3% by weight boric acid aqueous solution and 1000 parts by weight of a 2% by weight citric acid aqueous solution, respectively, followed by heating to 45 ° C. and stirring, 5% by weight polyvinyl alcohol (PVA-617, polymerization degree 1700) , Saponification degree 95.0 mol%, manufactured by Kuraray Co., Ltd.) 2000 parts by mass of aqueous solution, 1 part by mass of surfactant (Lapisol A30, manufactured by NOF Corporation) 100 parts by mass of aqueous solution, and 2700 parts by mass of pure water were added. 10000 parts by mass of a coating solution for a high refractive index layer was prepared.

The obtained coating solution for the low refractive index layer and the coating solution for the high refractive index layer were subjected to shearing treatment using CLEARMIX CLM-0.8S (manufactured by M Technique Co., Ltd.) which is a dispersing device. More specifically, in the shearing process, a rotary pump is used for a 350 cc vessel (processing chamber) having a screen slit (S2.0-24) having a minimum gap of 0.2 mm (2 × 10 ⁻⁴ m). The coating liquid was supplied at a flow rate of 1 L / min, and the rotor (R2) was rotated at a speed of 17 m / sec to perform a shearing process. The shear rate is 85000 (1 / sec).

Process (2)
While keeping the coating solution for the low refractive index layer and the coating solution for the high refractive index layer obtained in step (1) at 45 ° C., a polyethylene terephthalate film having a thickness of 50 μm (A4300 manufactured by Toyobo Co., Ltd .: double-sided easy adhesion layer) ) Nine layers were simultaneously coated at a speed of 6 m / min using a slide hopper coating apparatus so that nine layers of low refractive index layers and high refractive index layers were alternately laminated on each other. Was dried to prepare an infrared shielding film. Under the present circumstances, after performing a process (1), the time until performing a process (2) was 30 minutes. The average film thickness after drying was 150 nm for each low refractive index layer and 150 nm for each high refractive index layer.

(Example 2)
In the shearing process in the step (1), T.W. K. An infrared shielding film was produced in the same manner as in Example 1 except that Robomix (manufactured by PRIMIX Co., Ltd.) was used. In addition, the said shearing process was performed as follows. That is, a coating liquid is supplied at a flow rate of 1 L / min to a 350 cc vessel (processing chamber) having a screen slit portion having a minimum gap of 0.3 mm (3 × 10 ⁻⁴ m) using a rotary pump, and 3 m / min. Shearing was performed by rotating the rotor at a speed of sec. The shear rate is 10,000 (1 / sec).

(Example 3)
An infrared shielding film was produced in the same manner as in Example 2 except that the rotational speed of the rotor in step (1) was changed to 15 m / sec. The shear rate is 52000 (1 / sec).

(Example 4)
An infrared shielding film was produced in the same manner as in Example 1 except that Milder MDN303V (manufactured by Taiheiyo Kiko Co., Ltd.), which is a dispersing device, was used for the shearing treatment in the step (1). In addition, the said shearing process was performed as follows. That is, a coating liquid was supplied at a flow rate of 1 L / min using a rotary pump to a 350 cc vessel (processing chamber) provided with a screen slit portion having a minimum gap of 0.3 mm (3 × 10 ⁻⁴ m), and 26 m / min. Shearing was performed by rotating the rotor at a speed of sec. The shear rate is 90000 (1 / sec).

(Example 5)
The infrared shielding film was produced by the method similar to Example 1 except having used the pressure type homogenizer LAB1000 (product made from SMT Co., Ltd.) which is a dispersion device for the shearing process of a process (1). In addition, the said shearing process was performed as follows. That is, the coating liquid was supplied at a pressure of 500 bar to a processing chamber having a valve and a valve seat adjusted so that the minimum gap was 0.2 mm (2 × 10 ⁻⁴ m). At this time, the speed of the coating solution when passing through the minimum gap was 300 m / sec. The shear rate is 1500,000 (1 / sec).

(Comparative Example 1)
An infrared shielding film was produced in the same manner as in Example 1 except that a chemical gear pump GX-25S (manufactured by Iwaki Co., Ltd.), which is an inscribed gear pump, was used for the shearing treatment in the step (1). In addition, the said shearing process was performed as follows. That is, the coating liquid when passing through the meshing portion into the processing chamber where the minimum gap of the meshing portion between the drive gear (pinion) and the driven gear (internal gear) is 0.5 mm (5 × 10 ⁻⁴ m). The drive gear was adjusted so that the speed of the motor was 0.3 m / sec. The shear rate is 600 (1 / sec).

(Example 6)
An infrared shielding film was produced in the same manner as in Comparative Example 1 except that the passing speed of the meshing part in step (1) was changed to 1.5 m / sec. The shear rate is 3000 (1 / sec).

(Example 7)
The infrared shielding film was produced by the method similar to the comparative example 1 except having changed the passage speed of the meshing part of process (1) into 4.8 m / sec. The shear rate is 9600 (1 / sec).

(Comparative Example 2)
An infrared shielding film was produced in the same manner as in Example 1 except that the three-one motor LB series (manufactured by Shinto Kagaku Co., Ltd.), which is a high-speed stirring device, was used for the shearing treatment in the step (1). In addition, the said shearing process was performed as follows. That is, a stirring blade having an outer diameter of 50 nm is provided, and the coating liquid is supplied to a processing chamber in which the gap between the tip of the stirring blade and the inner wall is 10 mm (1 × 10 ⁻³ m), and stirring is performed at a speed of 0.8 m / sec. The coating solution was stirred by rotating the blade. The shear rate is 80 (1 / sec).

(Comparative Example 3)
The infrared shielding film was produced by the method similar to the comparative example 2 except having changed the rotational speed of the stirring blade of a process (1) into 3 m / sec. The shear rate is 300 (1 / sec).

(Comparative Example 4)
The infrared shielding film was produced by the method similar to the comparative example 2 except having changed the rotational speed of the stirring blade of a process (1) into 8 m / sec. The shear rate is 800 (1 / sec).

(Comparative Example 5)
Except that the gap between the stirring blade and the inner wall of the processing chamber of the apparatus used in step (1) was changed to 5 mm (5 × 10 ⁻⁴ m), and the rotation speed of the stirring blade was changed to 3 m / sec. Produced an infrared shielding film in the same manner as in Comparative Example 2. The shear rate is 600 (1 / sec).

(Example 8)
The infrared shielding film was produced by the method similar to the comparative example 5 except having changed the rotational speed of the stirring blade of a process (1) into 5 m / sec. The shear rate is 1000 (1 / sec).

Example 9
The gap between the tip of the processing chamber stirring blade and the inner wall of the apparatus used in the step () was changed to 3 mm (3 × 10 ⁻⁴ m), and the rotation speed of the stirring blade was changed to 7 m / sec. Except for this, an infrared shielding film was produced in the same manner as in Comparative Example 2. The shear rate is 2300 (1 / sec).

Table 1 below shows the relationship between the speed, the minimum gap, and the shear rate in Examples 1 to 9 and Comparative Examples 1 to 5.

[Evaluation of infrared shielding film]
The following performance evaluation was performed on the infrared shielding films manufactured in Examples 1 to 9 and Comparative Examples 1 to 5.

(Measurement of film thickness fluctuation rate)
The cross section of the infrared shielding film was observed using an electron microscope (FE-SEM, S-5000H type, manufactured by Hitachi, Ltd.). At this time, the number of fields was selected so that a length of 1 cm could be observed under the condition of an acceleration voltage of 2.0 kV. The images were digitized, transferred to a connected filing device (VIDEOBANK) and stored on the MO disk. Subsequently, the contrast was adjusted with an image processing apparatus, the film thickness of each layer was measured at 1000 points, and the average value (μ) of the film thickness and the standard deviation (σ) of the film thickness were calculated. Using the standard deviation (σ) of the film thickness as the film thickness fluctuation range, the film thickness fluctuation rate (V) with respect to the average value of the film thickness was obtained by the following equation (2).

According to the following criteria, the film thickness fluctuation rate of the infrared shielding film was evaluated from the obtained value:
○: Less than 3% Δ: 3% or more and less than 5% ×: 5% or more.

The results obtained are shown in Table 2 below.

(Measurement of color difference)
Using a spectrophotometer (using an integrating sphere, U-4000 type, manufactured by Hitachi, Ltd.), the back side on the measurement side of the manufactured infrared shielding film is roughened and light-absorbed with a black spray. By doing so, reflection of light on the back surface was prevented. Next, the reflectance in the visible light region (360 nm to 740 nm) is measured under the conditions of 5 degree regular reflection and 45 degree regular reflection, and the L ^* a ^* b ^* value is calculated from the obtained result. The color difference ΔE between the regular reflection condition and the 45 ° regular reflection condition was determined by the following equation (3).

According to the following criteria, the color difference of the infrared shielding film was evaluated from the obtained value:
○: Less than 10 Δ: 10 or more and less than 20 ×: 20 or more.

The results obtained are shown in Table 2 below.

As is clear from the results in Table 2, the infrared shielding films of Examples 1 to 9 had good results with respect to the film thickness variation rate and the color difference. That is, when a shearing process having a shear rate of 1000 (1 / sec) or more is applied to the coating solution, even when the film is thinned at the nano-order (150 nm in the embodiment), the variation in film thickness is suppressed, and the color unevenness is reduced. It is understood that an infrared shielding film with suppressed generation can be obtained. It can also be seen that the higher the shear rate, the better the result.

1 stator teeth,
2 rotor teeth,
3 shear gap,
4, 5, 14, 24, 34 coating solution,
11 Valve seat,
12 valves,
La, Lb, Lc, Ld gap,
21 Outer box,
22a, 22b gears,
31 inner wall,
32 Stirring blade.

Claims

A method for producing an optical film in which at least one optical functional layer having a film thickness of 1 to 1000 nm is formed on a substrate,
A step (1) of applying a shearing treatment at a shear rate of 1000 (1 / s) or more to the coating solution containing a polymer;
A step (2) of forming a coating film by applying the coating liquid obtained in the step (1) on a substrate;
Manufacturing method.
The manufacturing method according to claim 1, wherein the coating is performed at a speed of 1 m / min or more.
The manufacturing method according to claim 1 or 2, wherein the step (2) is performed within 3 hours after the step (1).
The manufacturing method according to any one of claims 1 to 3, wherein the shearing treatment is performed by a dispersing device, a high-speed stirring device, a discharging device, or a combination thereof.