JP2013080178A - Light-shielding film and infrared shield using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-shielding film excellent in optical characteristics formed using a high-concentration, metal oxide particle-containing aqueous coating liquid.SOLUTION: The light-shielding film comprises at least one unit where a high refractive index layer and a low refractive index layer are alternately stacked on a support. The high refractive index layer contains: a water-soluble polymer (1) which includes in a molecule a structural unit represented by the specified general formula (1) and has weight average molecular weight of 1000 to 30000; a water-soluble polymer (2) which has weight average molecular weight of 50000 or greater; and metal oxide particles.

Description

  The present invention relates to a light shielding film and an infrared shielding body using the same. More specifically, the present invention relates to a light shielding film having a high refractive index layer in which metal oxide particles are well dispersed and an infrared shielding body using the same.

  In recent years, due to increasing interest in energy saving measures, there has been an increasing demand for light shielding films that can be attached to window glass of buildings and vehicles to block the transmission of solar heat rays from the viewpoint of reducing the load on cooling equipment. .

  As a method for forming a light shielding film, a laminated film consisting of a structure in which a high refractive index layer and a low refractive index layer are alternately laminated is used by using a dry film forming method such as a vapor deposition method or a sputtering method. A method of forming has been proposed. However, the dry film forming method has problems such as a large vacuum apparatus used for forming, high manufacturing cost, difficult to enlarge, and limited to a heat-resistant material as a base material. Yes.

  A method of forming a light shielding film using a wet coating method instead of the dry film forming method having the above-described problems is known.

  For example, a high refractive index layer coating solution in which a thermosetting silicone resin or an ultraviolet curable acrylic resin containing metal oxide or metal compound fine particles is dispersed in an organic solvent is applied to the substrate by a wet coating method using a bar coater. A method of forming a transparent laminate by applying to a coating (see, for example, Patent Document 1), a rutile type titanium oxide, a heterocyclic nitrogen compound (eg, pyridine), an ultraviolet curable binder, and an organic solvent. A method for forming a transparent laminate by applying a composition for forming a refractive index coating film on a substrate by a wet coating method using a bar coater (for example, see Patent Document 2) is disclosed.

JP-A-8-110401 JP 2004-123766 A

  However, in the methods disclosed in Patent Document 1 and Patent Document 2, since the medium of the coating liquid for forming a high refractive index layer is mainly formed of an organic solvent, the high refractive index layer is formed and dried. As a result, a large amount of organic solvent is scattered, which causes environmental problems. Furthermore, in the method disclosed in the above patent document, a high refractive index layer is formed using an ultraviolet curable binder or a thermosetting binder as a binder, and then cured by ultraviolet rays or heat. It has film properties.

  In consideration of the above circumstances, multilayer coating using a water-based refractive index forming coating solution, rather than an organic solvent-based coating solution, can be manufactured at a low cost, can have a large area, is flexible, and has a near-infrared reflection. A light shielding film having excellent properties and high visible light transmittance and an infrared shielding body provided with the light shielding film are also conceivable. However, the compatibility between the long-term storage stability of the liquid and the haze and optical characteristics is not sufficient, and the liquid has not been put into practical use.

  Therefore, the present invention has been made in view of the above circumstances, and provides a light shielding film having a high refractive index layer that can be formed using an aqueous coating solution containing metal oxide particles at a high concentration. Objective.

  Another object of the present invention is to provide a light shielding film having excellent near-infrared reflectivity and / or visible light transmittance.

  Another object of the present invention is to provide an infrared shielding body using the light shielding film as described above.

  In order to solve the above problems, the present inventors have a problem in production while ensuring thickening in a low-temperature environment as a coating solution while using a water-based coating solution without using a large amount of an organic solvent. By improving the dispersion stability of the coating liquid, the light shielding film with high productivity, high light reflectivity and little light scattering was studied. As a result, by using a water-soluble polymer having a picolinic acid structure as a substituent having a weight average molecular weight of 30,000 or less for the high refractive index layer, the dispersibility of the metal oxide particles is improved. It was learned that a light shielding film can be formed with an aqueous coating liquid containing oxide particles, and the present invention has been completed.

  That is, the above object of the present invention is achieved by the following configuration.

1. A light shielding film having at least one unit in which a high refractive index layer and a low refractive index layer are alternately laminated on a support,
The high refractive index layer is
1) The following general formula (1):

In the general formula (1), R ¹ represents a hydrogen atom or a monovalent metal atom; R ² represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl having 6 to 12 carbon atoms. R ³ represents a hydrogen atom or a methyl group; X represents a single bond or a divalent linking group containing a carbonyl group; and m is an integer of 0 to 3.
A water-soluble polymer (1) having a weight average molecular weight of 1000 to 30,000, having a structural unit represented by
2) a light-shielding film comprising a water-soluble polymer (2) having a weight average molecular weight of 50,000 or more; and 3) metal oxide particles.

  2. The water-soluble polymer (1) further has in its molecule a structural unit having a hydroxyl group (—OH) or a amide group in its side chain. A light shielding film according to 1.

  3. 1. The content ratio of the structural unit represented by the general formula (1) in the water-soluble polymer (1) is 3 to 80 mol%. Or 2. A light shielding film according to 1.

  4). 1. A near-infrared shielding film, ~ 3. The light shielding film according to any one of the above.

  5). Above 1. ~ 4. An infrared shielding body comprising the light shielding film according to any one of the above items on at least one surface of a substrate.

  According to the present invention, even a water-based coating liquid having a high metal oxide particle concentration can form a high refractive index layer without causing aggregation. For this reason, the light shielding film excellent in near-infrared reflectivity and visible-light transmittance, and an infrared shielding body using the same can be provided.

The present invention is a light shielding film having at least one unit in which a high refractive index layer and a low refractive index layer are alternately laminated on a support,
The high refractive index layer is
1) The following general formula (1):

In the general formula (1), R ¹ represents a hydrogen atom or a monovalent metal atom; R ² represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl having 6 to 12 carbon atoms. R ³ represents a hydrogen atom or a methyl group; X represents a single bond or a divalent linking group containing a carbonyl group; and m is an integer of 0 to 3.
And a water-soluble polymer (1) having a weight average molecular weight of 1000 to 30,000 (hereinafter simply referred to as “water-soluble polymer”). (Also referred to as (1) ");
2) a water-soluble polymer having a weight average molecular weight of 50,000 or more (2) (hereinafter, also simply referred to as “water-soluble polymer (2)”); and 3) light containing metal oxide particles The present invention relates to a shielding film. The present invention is characterized in that a water-soluble polymer (1) having a specific structure and a weight average molecular weight is used for the high refractive index layer constituting the light shielding film.

  Conventionally, as a method of forming an infrared shielding film by a wet coating method, a coating solution for a high refractive index layer in which a thermosetting silicone resin containing metal oxide particles or an ultraviolet curable acrylic resin is dispersed in an organic solvent is used. , A method of forming a transparent laminate by applying on a substrate by a wet coating method using a bar coater; a composition for forming a high refractive index coating film composed of titanium oxide, an ultraviolet curable binder and an organic solvent, A method of forming a transparent laminate by applying a wet coat method using a spin coater to form a transparent laminate; a method of alternately laminating methanol dispersion slurry of spherical rutile-type titanium oxide particles and methanol silica sol, etc. has been reported. It was. However, in the manufacturing method described above, the formed film is too hard or the adhesion between the layers is insufficient, and when it is strongly bent, delamination occurs. There was a problem that the adhesiveness of the resin became insufficient.

  In order to solve these problems, a method of mixing metal oxide particles (for example, titanium dioxide particles) in a water-soluble binder and alternately laminating a high refractive index layer and a low refractive index layer is conceivable. However, this method has a problem that a dispersion in which metal oxide particles coexist in a water-soluble polymer as a binder has low stability as a coating solution for a high refractive index layer. Moreover, since the interlayer aggregation of the metal oxide particles occurs, the unevenness at the interface between the high refractive index layer and the low refractive index layer and the film surface becomes large, resulting in delamination between the high refractive index layer and the low refractive index layer. There was also a problem that the adhesion of the infrared shielding film to the glass was insufficient.

  In order to reduce aggregation of particles, it is conceivable to reduce the content (addition amount) of metal oxide (for example, titanium dioxide) particles in the solid content of the metal oxide particles. However, in this case, the difference in refractive index between the high refractive index layer and the low refractive index layer becomes small, and the infrared reflectance of the film is lowered, or in order to achieve a high infrared reflectance, the number of layers is reduced. It is necessary to increase (increase the thickness of the entire film). For this reason, in order to realize a higher refractive index, there has been a demand to increase the content of metal oxide particles in the coating solution.

  On the other hand, a method of adding a small amount of water-soluble polymer having a setting property is used for multilayer coating in an aqueous system. As such a water-soluble polymer, polyvinyl alcohol (PVA) having a weight average molecular weight of 50,000 or more, polymer gelatin having a weight average molecular weight of 100,000 or more, and the like are known. However, when the above water-soluble polymer is added, there is a problem that the dispersion stability of the metal oxide particles coexisting in the coating solution tends to be lowered. In consideration of this problem, after coating the metal oxide in advance with a water-soluble polymer having a lower molecular weight, that is, a weight average molecular weight of less than 30,000 (eg, gelatin, cellulose, thickening polysaccharide, etc.), the weight A method of adding a water-soluble polymer having an average molecular weight of 50,000 or more has also been proposed. However, in this case, although the dispersion stability is slightly improved, it is still not sufficient, and aggregation may occur when the dispersion is stored, which causes a problem in the storage stability of the coating liquid.

  On the other hand, the present invention is characterized in that a water-soluble polymer (1) having a picolinic acid structure in a side chain (substituent) having a weight average molecular weight of 30,000 or less is used for the high refractive index layer. When such a water-soluble polymer (1) is added, the dispersibility of the metal oxide particles in the coating solution is improved. Therefore, even if the content of the metal oxide particles in the coating solution is increased, the metal oxide Little or no particle agglomeration occurs.

  Here, the mechanism by which the dispersibility of the metal oxide particles in the coating solution is improved by adding the water-soluble polymer (1) is unknown, but is presumed as follows. The present invention is not limited by the following estimation. The water-soluble polymer (1) has a picolinic acid structure in its structural unit, but a carbonyl group (-C (= O)-moiety of -COOH) or a heterocyclic nitrogen atom (pyridine) in the picolinic acid structure. Since the nitrogen atom in the ring) is coordinated to the metal portion of the metal oxide particle, the water-soluble polymer (1) is firmly adsorbed on the surface of the metal oxide particle and protects the surface of the metal oxide particle. By such surface protection of the metal oxide particles, aggregation by the metal oxide particles is suppressed (that is, the water-soluble polymer (1) acts as an aggregation inhibitor of the metal oxide particles).

  For this reason, even if the metal oxide particle concentration in the coating liquid is increased by adding the water-soluble polymer (1) to the coating liquid, the metal oxide particles are not agglomerated in the coating liquid. It exhibits dispersibility and is excellent in dispersion stability (long-term storage stability of the coating solution). In addition, it is possible to reduce unevenness at the interface and film surface between the high refractive index layer and the low refractive index layer, the delamination between the high refractive index layer and the low refractive index layer hardly occurs, and excellent in haze, and glass, etc. Infrared shielding film having excellent adhesion to the substrate can be obtained.

  Moreover, since the metal oxide particle content in the high refractive index layer can be increased, the refractive index difference between the high refractive index layer and the low refractive layer can be widened. Thereby, even if the number of stacked layers is reduced, a high refractive index difference can be realized. Therefore, thinning of the light shielding film can be achieved. Moreover, the high refractive index layer obtained by the suppression of the aggregation by metal oxide particles by the metal oxide particle surface protection by water-soluble polymer (1) and the increase in metal oxide particle content has a low haze, and Excellent near-infrared reflectivity and visible light transparency.

  Therefore, the light shielding film of the present invention and the infrared shielding body provided with the light shielding film have a coating failure (for example, even if the coating liquid is stored for a long time during (a) formation (particularly during formation of a high refractive index layer). (B) low haze; (c) excellent near-infrared reflectivity; (d) excellent visible light transmission; and (e) flexibility. There are advantages such as being superior to. In the present specification, the “light shielding film” means a film that shields at least one of visible light and infrared light (near infrared light, middle infrared light, far infrared light). Preferably, the light shielding film of the present invention is an infrared shielding film, more preferably a near infrared shielding film.

  The light shielding film of the present invention has at least one unit in which a high refractive index layer and a low refractive index layer are alternately laminated on a support. Hereinafter, the components of the infrared shielding film of the present invention will be described in detail.

[Support]
Although it does not restrict | limit especially as a support body used for the light shielding film of this invention, It is preferable that it is a film support body. The film support may be transparent or opaque, and various resin films can be used. Specific examples thereof include polyolefin films (polyethylene, polypropylene, etc.), polyester films (polyethylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride, cellulose triacetate, etc., preferably polyester films.

  Although it does not specifically limit as a polyester film (henceforth polyester), It is preferable that it is polyester which has the film formation property which has a dicarboxylic acid component and a diol component as main structural components. The main constituent dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethanedicarboxylic acid, Examples thereof include cyclohexane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, diphenyl ketone dicarboxylic acid, and phenylindane dicarboxylic acid. Examples of the diol component include ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) propane, bis ( 4-Hydroxyphenyl) sulfone, bisphenol fluorene hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like. Among the polyesters having these as main constituent components, from the viewpoint of transparency, mechanical strength, dimensional stability, etc., dicarboxylic acid components such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, diol components such as ethylene glycol and 1 Polyester having 1,4-cyclohexanedimethanol as the main constituent is preferred. Of these, polyesters mainly composed of polyethylene terephthalate and polyethylene naphthalate, copolymer polyesters composed of terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, and mixtures of two or more of these polyesters are mainly used. Polyester as a constituent component is preferable. Here, the phrase “main component” means that the component occupies 50% by mass or more of all components, and preferably 80% by mass or more of all components.

  The thickness of the support according to the present invention is preferably 10 to 300 μm, more preferably 20 to 150 μm. Two or more supports may be stacked, and in this case, the type of the support may be the same or different.

[High refractive index layer]
The high refractive index layer according to the present invention includes a water-soluble polymer (1), a water-soluble polymer (2), and metal oxide particles. In the present specification, “water-soluble polymer” means a G2 glass filter (maximum pore 40) when dissolved in water at a concentration of 0.5% by mass at the temperature at which the water-soluble polymer is most dissolved. To 50 μm), the mass of the insoluble matter separated by filtration is 50% by mass or less (lower limit: 0% by mass) of the added water-soluble polymer.

<Water-soluble polymer (1)>
The water-soluble polymer (1) has the following general formula (1):

The structural unit represented by (structural unit (1)) is contained in the molecule. The end of the water-soluble polymer (1) is not particularly limited and is appropriately defined depending on the type of raw material (monomer) used, but is usually a hydrogen atom.

  By forming a high refractive index layer using a coating solution to which the water-soluble polymer (1) is added, the water-soluble polymer (1) is converted to a metal via a carbonyl group and / or a nitrogen atom present in picolinic acid. It is strongly adsorbed on oxide particles (for example, rutile titanium dioxide), and the surface of the metal oxide particles is coated with the water-soluble polymer (1). As a result, the metal oxides in the coating solution Aggregation can be prevented and the dispersion stability of the metal oxide particles can be improved. As a result, even if the concentration of the metal oxide particles in the coating solution is increased, the metal oxide particles do not aggregate in the coating solution, exhibiting good dispersibility, and also exhibiting dispersion stability (long-term Excellent storage stability. Moreover, since the metal oxide particle content in the high refractive index layer can be increased, the refractive index of the high refractive index layer can be increased, and the difference in refractive index between the high refractive index layer and the low refractive layer can be widened. . For this reason, even if the number of stacked layers is reduced, a high refractive index difference can be realized, and the light shielding film can be made thinner. Moreover, the high refractive index layer obtained by the suppression of the aggregation by metal oxide particles by the metal oxide particle surface protection by water-soluble polymer (1) and the increase in metal oxide particle content has a low haze, and Excellent near-infrared reflectivity and visible light transparency. The above effect is particularly remarkable when the metal oxide particles are titanium dioxide particles.

In the general formula (1), R ¹ represents a hydrogen atom or a monovalent metal atom. Here, although it does not restrict | limit especially as a monovalent metal atom, Lithium, sodium, potassium, rubidium, a cesium etc. are mentioned. In consideration of the suppression / prevention of aggregation of metal oxides in the coating solution and the dispersion stability of metal oxide particles, R ¹ is preferably a hydrogen atom, sodium, or potassium, and preferably a hydrogen atom. Is more preferable. M is an integer of 0 to 3, preferably 0 to 2, more preferably 0 or 1, and particularly preferably 0. “M is 0” means that the substituent R ² does not exist in the pyridine ring. When a plurality of R ² are present (m is 2 or 3), each R ² may be the same or different.

When R ² is present (m is 1, 2 or 3), R ² represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Here, the halogen atom is not particularly limited, and examples thereof include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Moreover, a C1-C8 alkyl group is a C1-C8 linear, branched or cyclic alkyl group, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, n-butyl group, Linear or branched such as isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group Chain alkyl groups; and cyclic alkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, and cyclooctyl group. The aryl group having 6 to 12 carbon atoms is not particularly limited, but is phenyl group, benzyl group, phenethyl group, o-, m- or p-tolyl group, 2,3- or 2,4-xylyl group, mesityl group. Naphthyl group, anthryl group, phenanthryl group, biphenylyl group, pyrenyl group and the like. Among these, in consideration of suppression / prevention of aggregation of metal oxides in the coating solution and dispersion stability of metal oxide particles, R ² is a hydrogen atom, a straight chain or branched chain having 1 to 4 carbon atoms. It is preferably a chain alkyl group, more preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom. R ³ represents a hydrogen atom or a methyl group. X represents a divalent linking group containing a single bond or a carbonyl group. Here, the divalent linking group containing a carbonyl group includes a carbonyl group (—C (═O) —) and a main chain [—C (R ³ ) CH ₂ —] derived from (meth) acrylic acid and picoline. It is a divalent group linking an acid structure. Specifically, the divalent linking group containing a carbonyl group includes —O—C (═O) —, —C (═O) —O—, —C (═O) —NH—, and —NH—. C (= O)-and the like. Among these, X is a single bond or —C (═O) —O— in consideration of suppression / prevention of aggregation of the metal oxide in the coating solution and dispersion stability of the metal oxide particles. It is preferable that it is a single bond. The single bond means that the main chain [—C (R ³ ) CH ₂ —] derived from (meth) acrylic acid and the picolinic acid structure are directly bonded.

In addition, the main chain [—C (R ³ ) CH ₂ —] derived from (meth) acrylic acid may be bonded to an arbitrary position of the pyridine ring via the linking group X, and the bonding position is not particularly limited. That is, the main chain [—C (R ³ ) CH ₂ —] derived from (meth) acrylic acid is bonded to the 3-position, 4-position, 5-position or 6-position of the pyridine ring via the linking group X, preferably It is bonded to the 3-position, 4-position or 5-position of the pyridine ring via the linking group X, and more preferably to the 3-position or 5-position of the pyridine ring via the linking group X.

  Specifically, the structural unit represented by the general formula (1) includes 3-vinylpicolinic acid, 4-vinylpicolinic acid, 5-vinylpicolinic acid, 3-vinyl-4-methylpicolinic acid, 3-vinyl- 4-ethylpicolinic acid, 3-vinyl-5-methylpicolinic acid, 3-vinyl-5-ethylpicolinic acid, 3-vinyl-4,6-dimethylpicolinic acid, 3-vinyl-4,6-diethylpicolinic acid, 3-acryloxypicolinic acid, 3-methacryloxypicolinic acid, and compounds having the following structure:

And a structural unit derived from a monovalent metal atom salt of the above compound. Of these, compounds selected from 3-vinylpicolinic acid and 3-methacryloxypicolinic acid; and structural units derived from sodium salts and potassium salts of the above compounds are preferred.

  The water-soluble polymer (1) only needs to have the structural unit (1) of the general formula (1). Here, when the water-soluble polymer (1) is a polymer composed only of the structural unit (1), the structural unit (1) constituting the water-soluble polymer (1) has a single structure. The unit (1) (that is, a homopolymer form) or a combination of two or more structural units (1) (that is, a copolymer form) may be used.

Alternatively, the water-soluble polymer (1) may have other structural units in addition to the structural unit (1) of the general formula (1). Here, other structural units are not particularly limited, but compounds having a hydroxyl group (—OH) in the side chain, compounds having an amide group, (meth) acrylic acid esters, styrenes, vinylcarbazoles, styryl oxalates. Examples include structural units derived from diazoles. Here, the amide group is not particularly limited, but is preferably a group represented by the formula: —C (═O) —N (R ⁴ ) (R ⁵ ). In the above formula, R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. In this case, the alkyl group is defined in the same manner as described for R ² and is preferably a hydrogen atom. Specifically, the compound having a hydroxyl group (—OH) in the side chain is not limited to the following, but 2-hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) Examples thereof include (meth) acrylic acid hydroxyalkyl esters such as acrylate and 2-hydroxybutyl (meth) acrylate. Examples of the compound having an amide group include, but are not limited to, (meth) acrylamides such as (meth) acrylamide, N-methyl (meth) acrylamide, and N-methylol (meth) acrylamide. (Meth) acrylates include, but are not limited to, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, phenyl (meth) acrylate , Biphenyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. Examples of styrenes include, but are not limited to, styrene, α-methylstyrene, vinyl naphthalene, vinyl biphenyl, and vinyl anthracene. Vinyl carbazoles include, but are not limited to, vinyl carbazole. The styryl oxadiazoles include, but are not limited to, 2-styryl-5-phenyl-1-oxa-3,4-diazole, 2-styrylphenyl-5-phenyl-1-oxa-3,4-diazole 2-styryl-5-phenyl-1-oxa-3,4-diazole, 2- (p-styrylphenyl-5- (pt-butylphenyl) -1-oxa-3,4-diazole, and the like. Among these, a structural unit having a hydroxyl group (—OH) in the side chain or a structural unit having an amide group is preferable, that is, the water-soluble polymer (1) has a structure having a hydroxyl group (—OH) in the side chain. It is preferable to further have a structural unit having a unit or an amide group in the molecule.The water-soluble polymer (1) having such other structural unit in the molecule is a metal in the coating solution. It is possible to effectively suppress / prevent aggregation of oxides and improve dispersion stability of metal oxide particles, more preferably other structural units are 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth). A structural unit derived from acrylate or (meth) acrylamide, wherein the other structural unit may be a single other structural unit or a combination of two or more other structural units. When the water-soluble polymer (1) is a copolymer composed of two or more kinds of structural units, the structural units may be block-shaped or random.

  When the water-soluble polymer (1) is composed of the structural unit (1) and other structural units, the structural unit (1) represented by the general formula (1) in the water-soluble polymer (1). The content ratio of is not particularly limited as long as the effect of the structural unit (1) can be sufficiently exerted. The content ratio of the structural unit (1) represented by the general formula (1) in the water-soluble polymer (1) is preferably 3 to 80 mol%, more preferably 4 to 65 mol%, It is especially preferable that it is 5-50 mol%. Within such a range, even if the concentration of the metal oxide particles in the coating liquid is increased, the metal oxide particles do not aggregate in the coating liquid, and thus good dispersibility, excellent dispersion stability (coating liquid) Long-term storage stability) and the content of metal oxide particles in the high refractive index layer can be increased, so that the refractive index of the high refractive index layer can be increased.

  In the present invention, the water-soluble polymer (1) has a weight average molecular weight of 1000 to 30,000. Here, when the weight average molecular weight of the water-soluble polymer (1) is less than 1000, the aggregation of the metal oxide particles in the coating solution cannot be sufficiently suppressed and prevented, and the dispersibility of the metal oxide particles is insufficient. It becomes. At this time, if the amount of the water-soluble polymer (1) is increased in order to suppress / prevent aggregation of metal oxide particles, the light shielding film becomes fragile or bleeds out in a high humidity environment. The visible light transmittance is reduced due to the above. On the other hand, when the weight average molecular weight of the water-soluble polymer (1) exceeds 30,000, aggregation of the metal oxide particles is induced upon mixing with the water-soluble polymer (2). The weight average molecular weight of the water-soluble polymer (1) is preferably 3000 to 28000, and more preferably 6000 to 2600. Within such a range, aggregation of the metal oxide particles in the coating solution can be further suppressed / prevented, and good dispersibility and excellent dispersion stability (long-term storage stability of the coating solution) can be further improved. In the present specification, the weight average molecular weight can be measured by a gel permeation chromatograph (GPC) method. More specifically, in this specification, the weight average molecular weight is a value measured by the GPC method under the following conditions.

  In the present invention, the content of the water-soluble polymer (1) in the high refractive index layer is not particularly limited as long as it is an amount that can ensure sufficient dispersibility of the metal oxide particles. The content (in terms of solid content) of the water-soluble polymer (1) in the high refractive index layer is preferably 10% by mass or more and 50% by mass or less, more preferably based on the total mass of the high refractive index layer. Is 15 mass% or more and 40 mass% or less. Within such a range, aggregation of the metal oxide particles in the coating solution can be further suppressed / prevented, and good dispersibility and excellent dispersion stability (long-term storage stability of the coating solution) can be further improved.

<Water-soluble polymer (2)>
The high refractive index layer according to the present invention contains the water-soluble polymer (2) having a weight average molecular weight of 50,000 or more in combination with the water-soluble polymer (1). The water-soluble polymer (2) is not particularly limited as long as it has a weight average molecular weight of 50,000 or more and is water-soluble, but usually acts as a binder. Specific examples include gelatin, celluloses, thickening polysaccharides, and polymers having reactive functional groups. Alternatively, the water-soluble polymer (2) may be a water-soluble polymer (1) having a similar structure except that the weight average molecular weight is 50,000 or more. Preferably, water-soluble polymer (2) has a different structural unit from water-soluble polymer (1). Further, a water-soluble polymer having low temperature thickening is more preferable. Thereby, the simultaneous multilayer coating suitability can be imparted to the coating liquid for forming the high refractive index layer. Examples of such water-soluble polymers include gelatin, celluloses, thickening polysaccharides, and polymers having reactive functional groups. The water-soluble polymer (2) may be used alone or in the form of a mixture of two or more.

  Hereinafter, these water-soluble polymers will be described. In the case where the water-soluble polymer (2) is a water-soluble polymer (1) having the same structure except that the weight average molecular weight is 50,000 or more, the water-soluble polymer (2) has a weight average molecular weight. Since other than this is the same as the water-soluble polymer (1), the description thereof is omitted here.

(gelatin)
Examples of gelatin used in the present invention include various types of gelatin that have been widely used in the field of silver halide photographic materials. 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 carboxyl 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 the descriptions of 1977 (Machillan), p. 55, Science Photo Handbook (above), p. 72-75 (Maruzen), Fundamentals of Photographic Engineering-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. Gelatin may be used alone or in the form of a mixture of two or more.

(Gelatin hardener)
In the high refractive index layer coating solution and the low refractive index layer coating solution, after forming the high refractive index layer or the low refractive index layer, the gelatin coating film is cured, and therefore a curing agent can be added as necessary. .

  As the hardener that can be used, known compounds that are used as hardeners for ordinary photographic emulsion layers can be used. For example, vinylsulfone compounds, urea-formalin condensates, melanin-formalin condensates, epoxy Organic hardeners such as benzene compounds, aziridine compounds, active olefins and isocyanate compounds, and inorganic polyvalent metal salts such as chromium, aluminum and zirconium.

(Cellulose)
As the celluloses that can be used in the present invention, water-soluble cellulose derivatives can be preferably used, for example, water-soluble cellulose derivatives such as methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and carboxylic acid group-containing cellulose. Examples thereof include carboxymethyl cellulose (cellulose carboxymethyl ether) and carboxyethyl cellulose. In addition, a cellulose may be used independently or may be used with the form of a 2 or more types of mixture.

(Thickening polysaccharide)
The thickening polysaccharide that can be used in the present invention is not particularly limited, and examples thereof include generally known natural simple polysaccharides, natural complex polysaccharides, synthetic simple polysaccharides, and synthetic complex polysaccharides. The details of these polysaccharides can be referred to “Biochemical Encyclopedia (2nd edition), Tokyo Chemical Doujinshi”, “Food Industry”, Vol. 31 (1988), p.

  The thickening polysaccharide referred to in the present invention is a polymer of saccharides and has many hydrogen bonding groups in the molecule, and the viscosity at low temperature and the viscosity at high temperature due to the difference in hydrogen bonding force between molecules depending on the temperature. This is a polysaccharide with a large difference in properties, and when metal oxide particles are added, hydrogen bonds or ionic bonds are formed with the metal oxide particles at low temperatures, causing viscosity increase or gelation. is there. When the metal oxide particles are added to 100 parts by mass of the thickening polysaccharide, the viscosity increase range is 15 ° C. compared to the viscosity at 15 ° C. before the addition of the metal oxide particles. It is 1.0 mPa · s or more, preferably 5.0 mPa · s or more, and more preferably 10.0 mPa · s or more. In this specification, a value measured with a Brookfield viscometer is adopted as the viscosity.

  Examples of the thickening polysaccharide applicable to the present invention include pectin, galactan (for example, agarose, agaropectin, etc.), galactomannoglycan (for example, locust bean gum, guaran, etc.), xyloglucan (for example, tamarind gum, Tamarind seed gum, etc.), glucomannoglycan (eg, salmon mannan, wood-derived glucomannan, xanthan gum, etc.), galactoglucomannoglycan (eg, softwood-derived glycan), arabinogalactoglycan (eg, soybean-derived glycan, Glycans derived from microorganisms, etc.), glucoraminoglycans (eg, gellan gum, etc.), glycosaminoglycans (eg, hyaluronic acid, keratan sulfate, etc.), alginic acid and alginates, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan The Natural polymers and polysaccharides derived from red algae such as Sereran. From the viewpoint of not reducing the dispersion stability of the metal oxide particles coexisting in the coating solution, those in which the structural unit does not have a carboxylic acid group or a sulfonic acid group are preferable. Examples of such polysaccharides include 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, it is known as tamarind seed gum known as xyloglucan whose main chain is glucose and side chain is glucose, or galactomannan (galactomannoglycan) whose main chain is mannose and whose side chain is glucose. Guar gum, cationized guar gum, hydroxypropyl guar gum, locust bean gum, tara gum, and arabinogalactan (arabinogalactoglycan) having a main chain of galactose and a side chain of arabinose can be preferably used. In the present invention, tamarind, tamarind seed gum, guar gum, cationized guar gum, and hydroxypropyl guar gum are particularly preferable. In addition, although the said polysaccharide thickener may be used independently or may be used with the form of 2 or more types of mixtures, it is preferable to use together 2 or more types of polysaccharide thickener.

(Polymers having reactive functional groups)
Examples of water-soluble polymers applicable to the present invention include polymers having reactive functional groups, such as polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymers, acrylic acid. Acrylic resins such as potassium-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, or acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, Styrene acrylic acid resin such as styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, or styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer, styrene -Sodium styrene sulfonate copolymer, styrene -2-hydroxyethyl acrylate copolymer, styrene-2-hydroxyethyl acrylate-potassium styrene sulfonate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinyl naphthalene-acrylic acid copolymer Vinyl acetate copolymers such as vinyl naphthalene-maleic acid copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic acid copolymer, and salts thereof Is mentioned. Among these, polyvinyl alcohols, polyvinyl pyrrolidones, and copolymers thereof are preferable.

  The polyvinyl alcohol preferably used in the present invention includes, in addition to normal polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, cation-modified polyvinyl alcohol having a cation-modified terminal and anion-modified polyvinyl alcohol having an anionic group. Modified polyvinyl alcohol is also included.

  The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 1,000 or more, and particularly preferably has an average degree of polymerization of 1,500 to 5,000. The degree of saponification is preferably 70 to 100%, more preferably 80 to 99.5%.

  As the cation-modified polyvinyl alcohol, for example, polyvinyl having a primary to tertiary amino group or a quaternary ammonium group in the main chain or side chain as described in JP-A-61-110483 Examples include alcohols, which 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, hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1, 1-dimethyl-3-dimethylaminopropyl) acrylamide and the like. The ratio of the cationic group-containing ethylenically unsaturated monomer in the cation-modified polyvinyl alcohol is preferably 0.1 to 10 mol%, more preferably 0.2 to 5 mol% with respect to vinyl acetate.

  Anion-modified polyvinyl alcohol is described in, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-206088, JP-A-61-237681 and JP-A-63-330779. Examples thereof include a copolymer of vinyl alcohol and a vinyl compound having a water-soluble group, or 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. Examples thereof include a block copolymer of a vinyl compound having a hydrophobic group as described and vinyl alcohol. Polyvinyl alcohol can be used in combination of two or more kinds having different degrees of polymerization and modification.

  In the present invention, a curing agent can be used to cure the water-soluble polymer (2) acting as a binder. The curing agent applicable here is not particularly limited as long as it causes a curing reaction with the water-soluble polymer (2), but when the water-soluble polymer (2) is polyvinyl alcohol, boric acid and The salt is preferred. Other known compounds can be used and are generally compounds having a group capable of reacting with a water-soluble polymer, or compounds that promote the reaction between different groups of the water-soluble polymer (2). Depending on the type of the water-soluble polymer (2), it is appropriately selected and used. Specific examples of the curing agent include, for example, epoxy curing agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl- 4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde curing agents (formaldehyde, glyoxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy) -1,3,5-S-triazine, etc.), active vinyl compounds (1.3.5-tris-acryloyl-hexahydro-S-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum and the like.

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

  Of the water-soluble polymer (2), at least one selected from the group consisting of polyvinyl alcohol, gelatin, tamarind, and tamarind seed gum is more preferable from the viewpoint of dispersibility of metal oxide particles, coating stability, and the like. .

  In the present invention, the water-soluble polymer (2) has a weight average molecular weight of 50,000 or more. Here, when the weight average molecular weight of the water-soluble polymer (2) is less than 50,000, aggregation of the metal oxide particles in the coating solution cannot be sufficiently suppressed and prevented, and the dispersibility of the metal oxide particles is poor. This is not preferable because it is sufficient. The weight average molecular weight of the water-soluble polymer (2) is preferably 10,000 to 1,000,000, and more preferably 50,000 to 500,000. Within such a range, aggregation of the metal oxide particles in the coating solution can be further suppressed / prevented, and good dispersibility and excellent dispersion stability (long-term storage stability of the coating solution) can be further improved. In the present specification, the weight average molecular weight is a value measured in the same manner as in the method defined by the water-soluble polymer (1).

  In the present invention, the content of the water-soluble polymer (2) in the high refractive index layer is not particularly limited as long as it can provide sufficient simultaneous multilayer coating suitability. The content (in terms of solid content) of the water-soluble polymer (2) in the high refractive index layer is preferably 5% by mass or more and 50% by mass or less, and preferably 10% by mass or more and 40% by mass with respect to the total mass of the high refractive index layer. % Or less is more preferable. Here, if the water-soluble polymer (2) is within the above range, sufficient transparency can be ensured without disturbing the film surface during drying of the coating film, and the content of the metal oxide can be relatively increased. Thus, the difference in refractive index between the high refractive index layer and the low refractive index layer can be easily increased.

  The mixing ratio of the water-soluble polymers (1) and (2) in the high refractive index layer is not particularly limited, but the amount of the water-soluble polymer (2) mixed with 100 parts by mass of the water-soluble polymer (1) is It is preferably 20 to 200 parts by mass, and more preferably 50 to 150 parts by mass. Within such a range, even if the concentration of the metal oxide particles in the coating solution is increased, the metal oxide particles do not aggregate in the coating solution and exhibit good dispersibility. Stability (long-term storage stability of the coating solution) can be achieved.

<Metal oxide particles>
In the present invention, metal oxide particles are included in either the high refractive index layer or the low refractive index layer. Preferably, the high refractive index layer or the low refractive index layer contains metal oxide particles.

The metal oxide particles used for the high refractive index layer preferably have a refractive index of 2.0 or more. For example, zirconium oxide (ZrO ₂ ), cerium oxide (CeO ₂ ), titanium oxide (TiO ₂ ), and the like can be given. Among these, from the viewpoint of the stability of the coating liquid for forming the high refractive index layer, zirconium oxide and titanium oxide are preferable, and titanium oxide (TiO ₂ ) is more preferable. Of TiO ₂ , rutile type is more preferable than anatase type because the high refractive index layer and the adjacent layer have high weather resistance due to low catalytic activity, and the refractive index becomes higher.

  The metal oxide particles used in the high refractive index layer preferably have an average particle size of 100 nm or less, more preferably 4 nm or more and 50 nm or less, and still more preferably 4 nm or more and 30 nm or less. . The average particle diameter is determined by observing the particle itself or the particles appearing on the cross section or surface of the refractive index layer with an electron microscope, measuring the particle diameter of 1,000 arbitrary particles, and calculating the simple average value (number average). Desired. Here, the particle diameter of each particle is represented by a diameter assuming a circle equal to the projected area.

  Hereinafter, rutile type titanium oxide particularly preferable as the metal oxide particles used in the high refractive index layer will be described in detail.

(Rutile titanium oxide)
In general, titanium oxide particles are often used in a surface-treated state for the purpose of suppressing photocatalytic activity on the particle surface and improving dispersibility in a solvent or the like. For example, titanium oxide particles Known are those in which the surface is covered with a coating layer made of silica and the particle surface is negatively charged, and in which the coating layer made of aluminum oxide is formed and the surface is positively charged at pH 8-10. .

  The metal oxide particles are preferably rutile (tetragonal) titanium oxide particles having a volume average particle size of 100 nm or less. The volume average particle size is more preferably 4 nm or more and 50 nm or less, and further preferably 4 nm or more and 40 nm or less. A volume average particle diameter of 100 nm or less is preferable from the viewpoint of low haze and excellent visible light transmittance.

The volume average particle diameter of the rutile-type titanium oxide particles refers to the particles themselves or the particles appearing on the cross section or surface of the refractive index layer, and the particle diameters of 1,000 arbitrary particles are measured. in a population of _{d 1, d 2 ··· d i} ··· d each particle _n 1 having a particle size of _{k, n 2 ··· n i ···} n k pieces existing metal oxide particles, particles When the surface area per one is a _i and the volume is v _i , the average particle diameter is weighted by the volume represented by the following formula 1.

  Furthermore, the rutile titanium oxide particles are preferably monodispersed. The monodispersion here means that the monodispersity obtained by the following formula 2 is 40% or less. More preferably, it is 30% or less, and further preferably 0.1 to 20%.

(Method for producing rutile titanium oxide sol)
As a method for producing a near-infrared reflective film, when preparing an aqueous high refractive index layer coating solution, the rutile type titanium oxide has a pH of 1.0 or more and 3.0 or less, and the zeta potential of the titanium particles is It is preferable to use an aqueous titanium oxide sol that is positive.

  In general, titanium oxide particles are often used in a state in which surface treatment is performed for the purpose of suppressing photocatalytic activity on the particle surface or improving dispersibility in a solvent or the like. It is known that the particle surface is covered with a coating layer made of silica and the surface of the particle is negatively charged, or the surface of the particle is positively charged at pH 8 to 10 where the coating layer made of aluminum oxide is formed. The use of an aqueous sol of titanium oxide that has a pH of 1.0 to 3.0 and has a positive zeta potential that is not subjected to such surface treatment can fill the film with high refractive index particles at a high concentration ( This is preferable in that there are few components that lower the refractive index.

  Examples of the method for preparing the rutile type titanium oxide sol include, for example, JP-A-63-17221, JP-A-7-819, JP-A-9-165218, JP-A-11-43327, JP-A-63-3. 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 production methods of rutile type titanium oxide, for example, “Titanium oxide—physical properties and applied technology”, Manabu Seino, p. 255-258 (2000) Gihodo Publishing Co., Ltd., or International Publication No. 2007/039953. The method of step (2) described in paragraph numbers “0011” to “0023” of the pamphlet can be referred to.

  In the production method according to the above step (2), titanium dioxide hydrate is treated with at least one basic compound selected from the group consisting of alkali metal hydroxides or alkaline earth metal hydroxides. After the step (1), the titanium dioxide dispersion obtained comprises a step (2) of treating with a carboxylic acid group-containing compound and an inorganic acid. In the present invention, an aqueous sol of rutile-type titanium oxide having a pH adjusted to 1.0 to 3.0 with the inorganic acid obtained in the step (2) can be used.

  The content of the metal oxide in the high refractive index layer is preferably 15% by volume or more and 50% by volume or less, more preferably 20% by volume or more and 40% by volume or less of the total volume of the high refractive index layer. It is. Moreover, as content of the metal oxide in a high refractive index layer, it is preferable that it is 10-80 mass% of the high refractive index layer total mass, and it is more preferable that it is 20-75 mass%.

  As the metal oxide particles used in the low refractive index layer, silicon dioxide is preferably used, and acidic colloidal silica sol is particularly preferably used.

  Colloidal silica preferably used is 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. For example, JP-A-57-14091 and JP-A JP 60-219083, JP 60-218904, JP 61-20792, JP 61-188183, JP 63-17807, JP 4-93284 JP-A-5-278324, JP-A-6-92011, JP-A-6-183134, JP-A-6-297830, JP-A-7-81214, JP-A-7-101142, Described in Kaihei 7-179029, JP-A-7-137431, International Publication No. 94/26530, etc. It is what is. Such colloidal silica may be a synthetic product or a commercially available product. The surface of the colloidal silica may be cation-modified, or may be treated with Al, Ca, Mg, Ba or the like.

  The average particle diameter of silicon dioxide is preferably 100 nm or less. Although the minimum of the average particle diameter of silicon dioxide is not specifically limited, Usually, it is 2 nm or more. The average particle diameter of primary particles of silicon dioxide dispersed in a primary particle state (particle diameter in a dispersion state before coating) is preferably 20 nm or less, more preferably 10 nm or less. In addition, the average particle size of the secondary particles is preferably 30 nm or less from the viewpoint of low haze and excellent visible light transmittance. The average particle size is determined by observing the particle itself or particles appearing on the cross section or surface of the refractive index layer with an electron microscope, measuring the particle size of 1,000 arbitrary particles, and calculating a 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.

  Moreover, in this invention, it is preferable that the thickness (thickness after drying) per layer of a high refractive index layer is 20-1000 nm, and it is more preferable that it is 50-500 nm.

  The refractive index of the high refractive index layer is preferably 1.70 to 2.50, more preferably 1.80 to 2.20.

  In the present specification, the refractive index of the high refractive index layer and the low refractive index layer described later can be obtained by the following method.

(Measurement method of refractive index)
A sample in which a layer (a high refractive index layer and a low refractive index layer) whose refractive index is to be measured is coated as a single layer on a support (PET film) is prepared, and the refractive index is obtained according to the following method. A U-4000 type (manufactured by Hitachi, Ltd.) was used as a spectrophotometer. After roughening the measurement-side back surface of each sample, light absorption treatment is performed with a black spray to prevent reflection of light on the back surface, and the visible light region (400 nm to The refractive index is obtained from the measurement result of the reflectance of 700 nm).

[Low refractive index layer]
The low refractive index layer according to the present invention usually comprises a water-soluble polymer (hereinafter also referred to as “water-soluble polymer (3)”) and metal oxide particles (hereinafter referred to as “second metal oxide particles”). including.

<Water-soluble polymer (3)>
The water-soluble polymer (3) is not particularly limited, and a water-soluble polymer usually used for a low refractive index layer constituting a light shielding film can be used. Specifically, the water-soluble polymers (1) and (2) can be used as the water-soluble polymer (3). For this reason, specific examples of the water-soluble polymer (3), preferred weight average molecular weight, usable curing agents, and the like are the same as those described in the columns of the water-soluble polymer (1) and (2). The description is omitted here.

  The content (in terms of solid content) of the water-soluble polymer (3) in the low refractive index layer is preferably 3 to 60% by mass with respect to the total mass of the low refractive index layer, and 10 to 50% by mass. It is more preferable that

<Second metal oxide particles>
The second metal oxide particles are not particularly limited, and metal oxide particles that are usually used when constituting a high refractive index layer or a low refractive index layer of the light shielding film are used in the same manner. For example, titanium dioxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), zinc oxide (ZnO), synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, lead titanate, red lead, yellow lead, zinc yellow, oxidation Examples thereof include chromium, ferric oxide, iron black, copper oxide, magnesium oxide, magnesium hydroxide, strontium titanate, yttrium oxide, niobium oxide, europium oxide, lanthanum oxide, zircon, and tin oxide.

  Among these, the metal oxide contained in the low refractive index layer is preferably synthetic amorphous silica or colloidal silica. In addition, you may further add the above-mentioned silicon dioxide (silica) as a metal oxide to the low-refractive-index layer based on this invention. In addition, since the specific description of the said metal oxide (metal oxide particle) is the same as that of the metal oxide (metal oxide particle) in the said high refractive index layer, description is abbreviate | omitted here.

  The second metal oxide particles preferably have an average particle diameter of 2 to 100 nm, more preferably 3 to 50 nm, and still more preferably 4 to 30 nm. In addition, when the second metal oxide particles are colloidal silica, the preferred average particle size of colloidal silica is usually 3 to 50 nm, but an average particle size of 4 to 30 nm is particularly preferable.

  The average particle diameter of the second 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, and measuring the particle diameter of 1,000 arbitrary particles. It is obtained as a 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.

  Further, the content of the metal oxide particles in the low refractive index layer is not particularly limited as long as an appropriate refractive index and transparency can be achieved. The content (in terms of solid content) of the metal oxide particles in the low refractive index layer is preferably 10 to 90% by mass and preferably 20 to 85% by mass with respect to the total mass of the low refractive index layer. More preferred. Here, if the metal oxide particles are in the above range, sufficient transparency can be secured, and the refraction of the high refractive index layer and the low refractive index layer can be relatively increased by increasing the content of the metal oxide. A sufficient rate difference can be secured.

  The thickness per layer of the low refractive index layer (thickness after drying) is preferably 20 to 800 nm, and more preferably 50 to 350 nm.

  The refractive index of the low refractive index layer is preferably 1.10 to 1.60, more preferably 1.30 to 1.55.

[Additive]
Various additives can be added to the high refractive index layer and the low refractive index layer according to the present invention as necessary. Hereinafter, the additive will be described.

(Inorganic polymer)
In the high refractive index layer and the low refractive index layer according to the present invention, an inorganic polymer such as a zirconium atom-containing compound or an aluminum atom-containing compound can be used as necessary.

  The compound containing a zirconium atom applicable to the present invention excludes zirconium oxide, and specific examples thereof include zirconium difluoride, zirconium trifluoride, zirconium tetrafluoride, hexafluorozirconium salt (for example, Potassium salt), heptafluorozirconate (for example, sodium salt, potassium salt or ammonium salt), octafluorozirconate (for example, lithium salt), fluorinated zirconium oxide, zirconium dichloride, zirconium trichloride, tetrachloride Zirconium, hexachlorozirconium salt (for example, sodium salt and potassium salt), zirconium oxychloride (zirconyl chloride), zirconium dibromide, zirconium tribromide, zirconium tetrabromide, zirconium bromide oxide, zirconium triiodide, four Diiodide Konium, zirconium peroxide, zirconium hydroxide, zirconium sulfide, zirconium sulfate, zirconium p-toluenesulfonate, zirconyl sulfate, sodium zirconyl sulfate, acidic zirconyl sulfate trihydrate, potassium zirconium sulfate, zirconium selenate, zirconium nitrate, nitric acid Zirconyl, zirconium phosphate, zirconyl carbonate, zirconyl ammonium carbonate, zirconium acetate, zirconyl acetate, zirconyl ammonium acetate, zirconyl lactate, zirconyl citrate, zirconyl stearate, zirconyl phosphate, zirconium oxalate, zirconium isopropylate, zirconium butyrate, Zirconium acetylacetonate, acetylacetone zirconium butyrate, zirconium stearate butyrate, Benzalkonium acetate, bis (acetylacetonato) dichloro zirconium and tris (acetylacetonato) chloro zirconium, and the like.

  Among these compounds, zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate, zirconyl acid chloride, zirconyl lactate and zirconyl citrate are preferable, and zirconyl ammonium carbonate, zirconyl acid chloride and zirconyl acetate are particularly preferable. Specific product names of the above compounds include zirconyl acetate ZA (trade name) manufactured by Daiichi Rare Element Chemical Co., Ltd., zirconyl acid chloride (trade name) manufactured by Daiichi Rare Element Chemical Co., Ltd., and the like. Can be mentioned.

  A compound containing a zirconium atom may be used alone, or two or more different compounds may be used in combination.

  Further, the compound containing an aluminum atom in the molecule that can be used in the present invention does not contain aluminum oxide. Specific examples thereof include aluminum fluoride, hexafluoroaluminic acid (for example, potassium salt), aluminum chloride, Basic aluminum chloride (eg, polyaluminum chloride), tetrachloroaluminate (eg, sodium salt), aluminum bromide, tetrabromoaluminate (eg, potassium salt), aluminum iodide, aluminate (eg, Sodium salt, potassium salt, calcium salt), aluminum chlorate, aluminum perchlorate, aluminum thiocyanate, aluminum sulfate, basic aluminum sulfate, potassium aluminum sulfate (alum), ammonium aluminum sulfate (ammonium alum) Sodium aluminum sulfate, aluminum phosphate, aluminum nitrate, aluminum hydrogen phosphate, aluminum carbonate, polysulfuric acid aluminum silicate, aluminum formate, aluminum acetate, aluminum lactate, aluminum oxalate, aluminum isopropylate, aluminum butyrate, ethyl acetate aluminum diisopropylate, aluminum Examples thereof include tris (acetylacetonate), aluminum tris (ethylacetoacetate), aluminum monoacetylacetonate bis (ethylacetoacetonate), and the like.

  Among these, aluminum chloride, basic aluminum chloride, aluminum sulfate, basic aluminum sulfate, and basic aluminum sulfate silicate are preferable, and basic aluminum chloride and basic aluminum sulfate are most preferable.

(amino acid)
In the present invention, the high refractive index layer or the low refractive index layer may further contain an amino acid. By including an amino acid, the dispersibility of the metal oxide particles in the high refractive index layer or the low refractive index layer can be improved.

  Here, the amino acid means a compound having an amino group and a carboxyl group in the same molecule, and may be any type of amino acid such as α-, β-, γ-, but has an isoelectric point of 6.5 or less. It is preferable that they are amino acids. Some amino acids have optical isomers, but in the present invention, there is no difference in effect due to optical isomers, and any isomer can be used alone or in racemic form. The isoelectric point of an amino acid refers to this pH value because the amino acid balances the positive and negative charges in the molecule at a specific pH and the overall charge is zero. In the present invention, it is preferable to use an amino acid having an isoelectric point of 6.5 or less. The isoelectric point of each amino acid can be determined by isoelectric focusing at a low ionic strength.

  For a detailed explanation of the amino acids according to the present invention, reference can be made to the description on pages 268 to 270 of the Chemical Dictionary 1 Reprint (Kyoritsu Shuppan; issued in 1960).

  In the present invention, preferred amino acids include glycine, alanine, valine, α-aminobutyric acid, γ-aminobutyric acid, β-alanine, serine, ε-amino-n-caproic acid, leucine, norleucine, phenylalanine, threonine, asparagine, asparagine. Examples thereof include acid, histidine, lysine, glutamine, glutamic acid, cysteine, methionine, proline, and hydroxyproline. For use as an aqueous solution, the solubility at the isoelectric point is preferably 3 g or more with respect to 100 g of water. For example, glycine, alanine, serine, histidine, lysine, glutamine, cysteine, methionine, proline, hydroxyproline and the like are preferable. It is more preferable to use serine or hydroxyproline having a hydroxyl group from the viewpoint that the metal oxide particles have a gentle hydrogen bond with the binder.

(Emulsion resin)
In the present invention, the high refractive index layer or the low refractive index layer may further contain an emulsion resin. By including the emulsion resin, the flexibility of the film is increased and the workability such as sticking to glass is improved.

  Here, the emulsion resin is a resin (preferably resin fine particles) obtained by emulsion-polymerizing an oil-soluble monomer in an aqueous solution containing a dispersant and using a polymerization initiator.

  Examples of the dispersant used in the polymerization of the emulsion include polyoxyethylene nonyl phenyl ether, in addition to low molecular weight dispersants such as alkyl sulfonate, alkyl benzene sulfonate, diethylamine, ethylenediamine, and quaternary ammonium salt. Examples thereof include polymer dispersants such as polyethylene ethylene laurate, hydroxyethyl cellulose, and polyvinyl pyrrolidone.

  The emulsion resin used in the present invention is preferably a resin in which fine resin particles having an average particle diameter of about 0.01 to 2.0 μm are dispersed in an emulsion state in an aqueous medium, and an oil-soluble monomer is used. It can be obtained by emulsion polymerization using a polymer dispersant having a hydroxyl group. There is no fundamental difference in the polymer component of the resulting emulsion resin depending on the type of dispersant used, but when emulsion polymerization is performed using a polymer dispersant having a hydroxyl group, the presence of hydroxyl groups is present on at least the surface of fine particles. It is presumed that the chemical and physical properties of the emulsion differ from the emulsion resin polymerized using other dispersants.

  The polymer dispersant containing a hydroxyl group is a polymer dispersant having a weight average molecular weight of 10,000 or more, and has a hydroxyl group substituted at the side chain or terminal. For example, an acrylic polymer such as sodium polyacrylate or polyacrylamide is used. Examples of such a polymer include those obtained by copolymerization of 2-ethylhexyl acrylate, polyethers such as polyethylene glycol and polypropylene glycol, and polyvinyl alcohol. Polyvinyl alcohol is particularly preferable.

  Polyvinyl alcohol used as a polymer dispersant is an anion-modified polyvinyl alcohol having an anionic group such as a cation-modified polyvinyl alcohol or a carboxyl group in addition to ordinary polyvinyl alcohol obtained by hydrolysis of polyvinyl acetate. Further, modified polyvinyl alcohol such as silyl-modified polyvinyl alcohol having a silyl group is also included. Polyvinyl alcohol has a higher effect of suppressing the occurrence of cracks when forming the ink absorbing layer when the average degree of polymerization is higher, but when the average degree of polymerization is within 5000, the viscosity of the emulsion resin is not high, and at the time of production Easy to handle. Accordingly, the average degree of polymerization is preferably 300 to 5000, more preferably 1500 to 5000, and particularly preferably 3000 to 4500. The saponification degree of polyvinyl alcohol is preferably 70 to 100 mol%, more preferably 80 to 99.5 mol%.

  Examples of the resin that is emulsion-polymerized with the above polymer dispersant include homopolymers or copolymers of ethylene monomers such as acrylic acid esters, methacrylic acid esters, vinyl compounds, and styrene compounds, and diene compounds such as butadiene and isoprene. Examples of the polymer include acrylic resins, styrene-butadiene resins, and ethylene-vinyl acetate resins.

(Other additives)
The high refractive index layer and the low refractive index layer according to the present invention can contain various other additives as necessary.

  Various other additives applicable to the high refractive index layer and the low refractive index layer according to the present invention are listed below. For example, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192, and JP-A-57-87989. , JP-A-60-72785, JP-A-61-14659, JP-A-1-95091, JP-A-3-13376, etc. Nonionic surfactants, JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-228771, and JP-A-4-219266 Fluorescent brighteners, sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, etc. Agents, lubricants such as diethylene glycol, preservatives, antifungal agents, antistatic agents, matting agents, heat stabilizers, antioxidants, flame retardants, crystal nucleating agents, inorganic particles, organic particles, thickeners, lubricants, infrared rays Examples include various known additives such as absorbents, dyes, and pigments.

[Production method of light shielding film]
Although the manufacturing method of the light shielding film of this invention is not restrict | limited in particular, The coating liquid for high refractive index layers which contains water-soluble polymer (1), water-soluble polymer (2), and metal oxide particle on a support body. And a manufacturing method including a step of applying a coating solution for a low refractive index layer containing the water-soluble polymer (3) and the second metal oxide particles is preferable.

  More specifically, for example, (1) a coating solution for a high refractive index layer containing a water-soluble polymer (1), a water-soluble polymer (2) and metal oxide particles is applied on a support and dried. After forming the high refractive index layer, a coating solution for the low refractive index layer containing the water-soluble polymer (3) and the second metal oxide particles is applied and dried to form the low refractive index layer, and light shielding Method for forming a film; (2) A low-refractive index layer is formed by applying a coating solution for a low-refractive index layer containing a water-soluble polymer (3) and second metal oxide particles on a support and drying it. Then, a coating solution for a high refractive index layer containing a water soluble polymer (1), a water soluble polymer (2) and metal oxide particles is applied and dried to form a high refractive index layer, and a light shielding film is formed. (3) A high refractive index layer comprising a water-soluble polymer (1), a water-soluble polymer (2) and metal oxide particles on a support. The coating solution and the coating solution for the low refractive index layer containing the water-soluble polymer (3) and the second metal oxide particles are alternately and successively applied, and then dried to obtain a high refractive index layer and a low refractive index layer. (4) A coating solution for a high refractive index layer containing a water-soluble polymer (1), a water-soluble polymer (2) and metal oxide particles, and a water-soluble polymer (3) And a coating solution for the low refractive index layer containing the second metal oxide particles are simultaneously applied and dried to form a light shielding film including the high refractive index layer and the low refractive index layer. It is done. Among these, the method (4), which is a simpler manufacturing process, is preferable.

  Hereinafter, the simultaneous multilayer coating method, which is a preferred production method (coating method) of the present invention, will be described in detail.

(solvent)
The solvent for preparing the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is not particularly limited, but water, an organic solvent, or a mixed solvent thereof is preferable.

  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 thereof include ethers such as propylene glycol monomethyl ether and ethylene glycol monoethyl ether, amides such as dimethylformamide and N-methylpyrrolidone, and ketones such as acetone, methyl ethyl ketone, acetylacetone and cyclohexanone. These organic solvents may be used alone or in combination 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.

(Concentration of coating solution)
The concentration of the water-soluble polymers (1) and (2) in the coating solution for the high refractive index layer and the concentration of the water-soluble polymer (3) in the coating solution for the low refractive index layer are not particularly limited. The concentration is preferably such that an appropriate viscosity of each coating solution can be achieved when performing multilayer coating. Here, the appropriate viscosity of the coating solution is appropriately selected depending on the coating method as described above.

  Moreover, it is preferable that the density | concentration of the metal oxide particle in the coating liquid for high refractive index layers is 2-50 mass%. It is preferable that the density | concentration of the 2nd metal oxide particle in the coating liquid for low refractive index layers is 2-50 mass%.

  Further, the mass ratio (F / B) between the metal oxide particles and the water-soluble polymer in the coating solution for the high refractive index layer and the coating solution for the low refractive index layer falls within the numerical range described in the column for the intermediate layer. Thus, it is preferable to add metal oxide particles and a water-soluble polymer to the coating solution.

(Method for preparing coating solution)
The method for preparing the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is not particularly limited. For example, a water-soluble polymer, metal oxide particles, and other additives added as necessary. The method of adding and stirring and mixing is mentioned. At this time, the order of addition of the water-soluble polymer, metal oxide particles, and other additives used as necessary is not particularly limited, and each component may be added and mixed sequentially while stirring. However, they may be added and mixed at once. If necessary, it is further adjusted to an appropriate viscosity using a solvent.

(Viscosity of coating solution)
For example, the viscosity at 40 ° C. of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer when simultaneous multilayer coating is performed by the slide hopper coating method or the slide bead coating method is preferably in the range of 5 to 100 mPa · s. 10 to 50 mPa · s is more preferable. The viscosity at 40 ° C. of the coating solution for high refractive index layer and the coating solution for low refractive index layer at the time of simultaneous multilayer coating by the slide curtain coating method is preferably in the range of 5 to 1200 mPa · s, and 25 to 500 mPa · s. -The range of s is more preferable.

  Further, the viscosity at 15 ° C. of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is preferably 5 mPa · s or more, more preferably 100 to 30,000 mPa · s, and more preferably 3,000 to 30,000 mPa · s. s is more preferable, and 10,000 to 30,000 mPa · s is particularly preferable.

(Coating and drying method)
The coating and drying method is not particularly limited, but the coating solution for the high refractive index layer and the coating solution for the low refractive index layer are heated to 30 ° C. or higher and the coating solution for the high refractive index layer and the low refractive index layer are heated on the support. After simultaneous multi-layer coating of the rate layer coating solution, the temperature of the formed coating film is preferably cooled (set) preferably to 1 to 15 ° C. and then dried at 10 ° C. or higher. More preferable drying conditions are a wet bulb temperature of 5 to 50 ° C. and a film surface temperature of 10 to 50 ° C. Moreover, as a cooling method immediately after application | coating, it is preferable to carry out by a horizontal set system from a viewpoint of the uniformity improvement of the formed coating film. Furthermore, the coating method is not particularly limited, and a known method can be used. For example, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a slide type curtain coating method, or a hopper described in US Pat. Nos. 2,761,419 and 2,761,791 A slide bead coating method, an extrusion coating method, etc. are preferably used.

  What is necessary is just to apply | coat so that the coating thickness of the coating liquid for high refractive index layers and the coating liquid for low refractive index layers may become the thickness at the time of preferable drying as shown above.

  After application, the time from application of cold air to completion of setting (setting time) is preferably within 5 minutes, and preferably within 2 minutes. Further, the lower limit time is not particularly limited, but it is preferable to take 45 seconds or more. If the set time is too short, mixing of the components in the layer may be insufficient. On the other hand, if the set time is too long, the interlayer diffusion of the metal oxide particles proceeds, and the refractive index difference between the high refractive index layer and the low refractive index layer may be insufficient.

  The set time can be adjusted by adjusting the concentration of water-soluble polymer and metal oxide particles, and adding other components such as gelatin, pectin, agar, carrageenan, gellan gum and other known gelling agents. It can be adjusted by doing.

  The temperature of the cold air is preferably 0 to 25 ° C, and more preferably 5 to 15 ° C. Moreover, although the time for which a coating film is exposed to cold wind also depends on the conveyance speed of a coating film, it is preferable that it is 10 to 120 seconds.

  Moreover, when storing the light shielding film of the present invention, it is preferable to store it after it is overcoated and dried, and then stored in a roll or after being cut into a sheet. Storing at a temperature of 30 ° C. or higher for a certain time, for example, 1 day to 1 month, helps to reduce coating unevenness. Preferable storage conditions are 30 to 50 ° C. and 1 to 30 days.

[Membrane design]
In general, in the light shielding film, it is preferable to design a large difference in refractive index between the high refractive index layer and the low refractive index layer from the viewpoint of increasing the infrared reflectance with a small number of layers. In the present invention, the difference in refractive index between at least two adjacent layers (high refractive index layer and low refractive index layer) is 0.1 or more, preferably 0.2 or more, more preferably 0.3 or more. Yes, more preferably 0.4 or more. The limit of the refractive index difference is not particularly limited, but is usually 1.4 or less from the viewpoint of improving the reflectance and reducing the number of layers.

  Since reflection at the interface between adjacent layers depends on the refractive index ratio between the layers, the larger the refractive index ratio, the higher the reflectance. In addition, when the optical path difference between the reflected light on the surface of the layer and the reflected light on the bottom of the layer is a relationship expressed by n · d = wavelength / 4 when viewed as a single layer film, the reflected light is controlled to be strengthened by the phase difference. The reflectance can be increased. Here, n is the refractive index, d is the physical film thickness of the layer, and n · d is the optical film thickness. By utilizing this optical path difference, reflection can be controlled. Using this relationship, the refractive index and film thickness of each layer are controlled to control the reflection of visible light and near infrared light. That is, the reflectance in a specific wavelength region can be increased by the refractive index of each layer, the film thickness of each layer, and the way of stacking each layer.

  The light-shielding film of the present invention changes visible wavelength shielding film and infrared (near-infrared light, mid-infrared light, far-infrared light, preferably near-infrared light) by changing the specific wavelength region that increases the reflectance. It can be set as a shielding film. In other words, when the specific wavelength region for increasing the reflectance is set to the visible light region, a visible light shielding (reflection) film is obtained, and when the specific wavelength region is set to the infrared region, an infrared light shielding (reflection) film is obtained.

  What is necessary is just to set it as a near-infrared-light reflection film when using the light-shielding film of this invention for a heat-shielding film. A multilayer film in which films having different refractive indexes are laminated on a polymer film is formed, and the transmittance in the visible light region shown in JIS R3106-1998 is 50% or more and the reflectance is in the region of wavelength 900 to 1400 nm. It is preferable to design the optical film thickness and unit so as to have a region exceeding 40%.

  The infrared region of the incident spectrum of direct sunlight is related to the increase in indoor temperature, and by blocking this, the increase in indoor temperature can be suppressed. Looking at the cumulative energy ratio from the shortest infrared wavelength (760 nm) to the longest wavelength 3200 nm based on the weight coefficient described in Japanese Industrial Standard JIS R3106-1998, the entire infrared region from the wavelength 760 nm to the longest wavelength 3200 nm When the cumulative energy from 760 nm to each wavelength when the total energy of 100 is taken as 100, the total energy from 760 to 1300 nm occupies about 75% of the entire infrared region. Therefore, shielding the wavelength region up to 1300 nm is efficient in energy saving effect by heat ray shielding.

  When the reflectance in the near-infrared light region (760 to 1300 nm) is about 80% or more at the maximum peak value, a decrease in the body temperature is obtained by sensory evaluation. For example, there was a clear difference when the temperature at the window facing the southeast method in the morning of August shielded the reflectance in the near infrared light range to about 80% at the maximum peak value.

  As a result of obtaining a multilayer film structure necessary for developing such a function by optical simulation (FTG Software Associates Film DESIGN Version 2.23.3700), the refractive index is 1.9 or more, preferably 2.0 or more. It has been found that excellent characteristics can be obtained when 6 or more layers are laminated using a high refractive index layer. For example, looking at the simulation results of a model in which eight layers of high refractive index layers and low refractive index layers (refractive index = 1.35) are alternately stacked, the reflectance is 70 when the refractive index of the high refractive index layer is 1.8. However, the reflectance of about 80% can be obtained at 1.9. Further, in the model in which the high refractive index layer (refractive index = 2.2) and the low refractive index layer (refractive index = 1.35) are alternately stacked, the reflectance does not reach 60% when the number of stacked layers is 4. However, when there are 6 layers, a reflectance of about 80% can be obtained.

[Light shielding film]
The light shielding film of the present invention has at least one unit consisting of a high refractive index layer and a low refractive index layer on a support, and an intermediate layer between the high refractive index layer and the low refractive index layer. May be further arranged. Furthermore, as an optical characteristic of the light shielding film of the present invention, the transmittance in the visible light region measured by JIS R3106-1998 is 50% or more, and the reflectance exceeds 50% in the wavelength region of 900 nm to 1400 nm. It is preferable to have a region.

  The light shielding film of the present invention may have a structure having at least one unit composed of a high refractive index layer and a low refractive index layer on the support, but the total number of the high refractive index layer and the low refractive index layer. As an upper limit, it is preferable that it is 100 layers or less, ie, 50 units or less, More preferably, it is 40 layers (20 units) or less, More preferably, it is 20 layers (10 units) or less.

  In addition, the whole thickness of the light shielding film of this invention becomes like this. Preferably they are 12 micrometers-315 micrometers, More preferably, they are 15 micrometers-200 micrometers, More preferably, they are 20 micrometers-100 micrometers. Thus, the light shielding film of the present invention can obtain a high infrared reflectance with a thinner film thickness than the conventional light shielding film.

  The light shielding film of the present invention is a conductive layer, an antistatic layer, a gas barrier layer, an easy-adhesion layer (adhesion layer) for the purpose of adding further functions under the support or on the outermost surface layer opposite to the support. Layer), antifouling layer, deodorant layer, droplet layer, slippery layer, hard coat layer, wear resistant layer, antireflection layer, electromagnetic wave shielding layer, ultraviolet absorbing layer, infrared absorbing layer, printing layer, fluorescent light emitting layer , Hologram layer, release layer, adhesive layer, adhesive layer, infrared cut layer (metal layer, liquid crystal layer) other than high refractive index layer and low refractive index layer of the present invention, colored layer (visible light absorbing layer), laminated glass You may have one or more of functional layers, such as an intermediate film layer utilized.

[Application of light shielding film]
The light shielding film of the present invention can be applied to a wide range of fields. For example, film for window pasting such as heat ray reflecting film that gives heat ray reflecting effect, and pasting to equipment (base) exposed to sunlight for a long time such as outdoor windows of buildings and automobile windows, for agricultural greenhouses It is used mainly for the purpose of improving weather resistance as a film or the like. In particular, the light shielding film of the present invention is suitably used for a member to be bonded to a substrate such as glass or a glass substitute resin directly or via an adhesive.

  That is, this invention also provides the infrared shielding body which provided the light shielding film of this invention, or the light shielding film obtained by the manufacturing method of this invention on the at least one surface of the base | 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 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 light shielding film of the present invention and the substrate is preferably installed so that the light shielding film is on the sunlight (heat ray) incident surface side. In addition, it is preferable to sandwich the light shielding film of 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 light shielding film of the present invention is installed outdoors or on the outside of a vehicle (for external application), it is preferable because of environmental durability.

  Examples of the adhesive or pressure-sensitive adhesive applicable to the present invention include an adhesive or pressure-sensitive adhesive mainly composed of a photocurable or thermosetting resin.

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

  Moreover, you may use the polyvinyl butyral type resin used as an intermediate | middle layer of a laminated glass, or ethylene-vinyl acetate copolymer type resin as said adhesive agent or adhesive. Specific examples thereof include, for example, plastic polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., Mitsubishi Monsanto Co., Ltd.), ethylene-vinyl acetate copolymer (manufactured by DuPont, manufactured by Takeda Pharmaceutical Company Limited, duramin), and modified ethylene-acetic acid. Vinyl copolymer (manufactured by Tosoh Corporation, Mersen G). In the adhesive layer or the adhesive layer, an ultraviolet absorber, an antioxidant, an antistatic agent, a heat stabilizer, a lubricant, a filler, a colorant, an adhesion (adhesion) adjusting agent, and the like may be appropriately added and blended.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

  Production Example 1

(1) Synthesis of monomer (3-vinylpicolinic acid) Hydrogen chloride gas was blown in for 5 hours while refluxing 25 g of 3-hydroxypicolinic acid and 500 ml of methanol solution, and after removing hydrogen chloride by nitrogen bubbling, under reduced pressure Methyl hydrochloride of 3-hydroxypicolinic acid obtained by removing methanol is dissolved in water, neutralized with sodium bicarbonate, the precipitated solid is filtered and dried to give 20 g of white 3-methylpicolinate as a white solid Ester isolated. Next, a solution of 20 g of 3-hydroxypicolinic acid methyl ester, 200 g of methylene chloride and 30 g of triethylamine was cooled to 0 ° C., and 40 g of anhydrous trifluoromethanesulfonic acid was added dropwise over 15 minutes, followed by stirring at room temperature for 3 hours. The solution was diluted with methylene chloride, washed with water, and the organic layer was dried over anhydrous sodium sulfate and evaporated to obtain 22 g of 3-trifluoromethanesulfoxypicolinic acid methyl ester. To 22 g of 3-trifluoromethanesulfoxypicolinic acid methyl ester, a solution of tributylvinyltin, lithium chloride, palladium dichlorobis (triphenylphosphine), 2,6-di-t-butylphenol and dimethylformamide was added under a nitrogen stream. The mixture was heated and stirred at 3 ° C for 3 hours. The reaction solution was cooled, diluted with hexane, and washed with water. The organic layer was dried over anhydrous sodium sulfate, evaporated, purified by silica gel chromatography, and microdistilled to obtain 15 g of 3-vinylpicolinic acid methyl ester. A solution of 15 g of 3-vinylpicolinic acid methyl ester, 200 g of methanol, 10 g of water and 2 g of potassium carbonate was refluxed for 3 hours, neutralized with 0.1 N hydrochloric acid and evaporated. By recrystallizing from methanol, 10 g of 3-vinylpicolinic acid was obtained.

(2) Synthesis of polymer (1) (3-vinylpicolinic acid and 2-hydroxyethyl acrylate copolymer) To a nitrogen-substituted flask, 12.0 g of 3-vinylpicolinic acid, 2-hydroxyethyl acrylate (2-HEA) ) 50.0 g, azobisvaleronitrile 1.3 g, and dimethylformamide 450 ml were added, and the mixture was heated and stirred at 80 ° C. for 5 hours. The reaction solution was poured into 1 liter of toluene and purified by reprecipitation to obtain 50 g of white powder. The weight average molecular weight by GPC is 11000, and it is confirmed from ¹ H-NMR that the composition of 3-vinylpicolinic acid and 2-hydroxyethyl acrylate (2-HEA) is a copolymer with a molar ratio of 20:80. This copolymer is referred to as polymer (1).

Production Example 2
In the same manner as in Production Example 1, 3-vinylpicolinic acid was synthesized.

To a flask purged with nitrogen, 12.0 g of 3-vinylpicolinic acid, 62.0 g of 2-hydroxypropyl methacrylate (2-HPMA), 1.3 g of azobisvaleronitrile, and 450 ml of dimethylformamide were added and heated at 80 ° C. for 5 hours. Stir. The reaction solution was poured into 1 liter of toluene and purified by reprecipitation to obtain 60 g of white powder. The weight average molecular weight by GPC was 13000, and it was confirmed from ¹ H-NMR that 3-vinylpicolinic acid / 2-hydroxypropyl methacrylate (2-HPMA) was a copolymer having a molar ratio of 20:80. Let the copolymer be a polymer (2).

Production Example 3
In the same manner as in Production Example 1, 3-vinylpicolinic acid was synthesized.

To a flask purged with nitrogen, 12.0 g of 3-vinylpicolinic acid, 32 g of acrylamide (AM), 1.3 g of azobisvaleronitrile, and 450 ml of dimethylformamide were added, and the mixture was heated and stirred at 80 ° C. for 5 hours. The reaction solution was poured into 1 liter of toluene and purified by reprecipitation to obtain 35 g of white powder. The weight average molecular weight by GPC was 9000, and it was confirmed from ¹ H-NMR that 3-vinylpicolinic acid / acrylamide (AM) was a copolymer with a molar ratio of 20:80. 3).

Production Example 4
In the said manufacture example 1, except having changed 3-vinyl picolinic acid into 3g and 2-hydroxyethyl acrylate (2-HEA) to 60g, weight average molecular weight is 25000 by performing the same operation as manufacture example 1. A copolymer of 3-vinylpicolinic acid and 2-hydroxyethyl acrylate having a molar ratio of 3 to 97 is obtained, and this copolymer is referred to as polymer (4).

Production Example 5
A weight average molecular weight of 21000 was obtained by performing the same operation as in Production Example 1 except that 5-vinylpicolinic acid was changed to 5 g and 2-hydroxyethyl acrylate (2-HEA) was changed to 58 g in Production Example 1. A copolymer of 3-vinylpicolinic acid and 2-hydroxyethyl acrylate having a molar ratio of 5 to 95 is obtained, and this copolymer is referred to as polymer (5).

Production Example 6
A weight average molecular weight of 19000 was obtained in the same manner as in Production Example 1 except that 8 g of 3-vinylpicolinic acid and 55 g of 2-hydroxyethyl acrylate (2-HEA) were changed to Production Example 1. A copolymer of 3-vinylpicolinic acid and 2-hydroxyethyl acrylate having a molar ratio of 10 to 90 is obtained, and this copolymer is referred to as polymer (6).

Production Example 7
By performing the same operation as in Production Example 1 except that 35 g of 3-vinylpicolinic acid and 30 g of 2-hydroxyethyl acrylate (2-HEA) were changed in Production Example 1, the weight average molecular weight was 8500. Thus, a copolymer of 3-vinylpicolinic acid and 2-hydroxyethyl acrylate having a molar ratio of 50:50 is obtained, and this copolymer is referred to as polymer (7).

Production Example 8
By performing the same operation as in Production Example 1 except that 3-vinylpicolinic acid was changed to 55 g and 2-hydroxyethyl acrylate (2-HEA) was changed to 15 g in Production Example 1, the weight average molecular weight was 11000. A copolymer of 3-vinylpicolinic acid and 2-hydroxyethyl acrylate having a molar ratio of 80:20 is obtained, and this copolymer is referred to as polymer (8).

Production Example 9
By performing the same operation as in Production Example 1 except that 2-hydroxyethyl acrylate (2-HEA) was not used and 60 g of 3-vinylpicolinic acid was used in Production Example 1, the weight average molecular weight was 8000. Thus, a homopolymer of 3-vinylpicolinic acid is obtained, and this homopolymer is referred to as polymer (9).

Production Example 10
In the above Production Example 1, except that azobisvaleronitrile was changed to 3 g, the same operation as in Production Example 1 was carried out, whereby the weight average molecular weight was 800, and 3-vinylpicolinic acid and 2-hydroxyethyl acrylate A copolymer having a molar ratio of 20 to 80 is obtained, and this copolymer is referred to as polymer (9).

Production Example 11
In the above Production Example 1, except that the amount of azobisvaleronitrile was changed to 1 g and the heating and stirring temperature was changed to 85 ° C., the same operation as in Production Example 1 was carried out to obtain a weight average molecular weight of 35000 and 3-vinylpicolinic acid. And 2-hydroxyethyl acrylate having a molar ratio of 20 to 80 is obtained, and this copolymer is referred to as polymer (11).

Production Example 12
In the above Production Example 1, the same operation as in Production Example 1 except that 32 g of 3-methacryloxypicolinic acid was used instead of 3-vinylpicolinic acid and 2-hydroxyethyl acrylate (2-HEA) was changed to 41 g. To obtain a copolymer having a weight average molecular weight of 12000 and a composition of 3-methacryloxypicolinic acid and 2-hydroxyethyl acrylate (2-HEA) in a molar ratio of 30 to 70. Is a polymer (12).

Production Example 13
In the said manufacture example 1, 3-vinyl picolinic acid is not used but 2-hydroxyethyl acrylate (2-HEA) is changed into 40 g, By performing operation similar to manufacture example 1, weight average molecular weight is obtained. At 23000, a homopolymer of 2-hydroxyethyl acrylate (2-HEA) is obtained, and this homopolymer is referred to as polymer (13).

[Preparation of coating solution]
(Preparation of high refractive index layer coating solution 1)
After heating 200 mass parts of 10 mass% zirconia sol (Zircosol ZSL-10T 1st rare element chemical industry Co., Ltd. average particle diameter of 10-30 nm) to 50 degreeC, stirring, 5 of polymer (1) 125 parts by mass of a mass% aqueous solution was added and stirred for 30 minutes. Next, 20 parts by mass of a 3% by mass boric acid aqueous solution was added, and 100 parts by mass of a 5% by mass aqueous solution of polyvinyl alcohol (PVA235, weight average molecular weight 150,000, manufactured by Kuraray Co., Ltd.) and 150 parts by mass of pure water were added. After stirring for 90 minutes, 0.45 parts by mass of a 5% by mass surfactant aqueous solution (Cotamine 24P, manufactured by Kao Corporation) was added to prepare a high refractive index layer coating solution 1.

(Preparation of high refractive index layer coating solution 2)
The high refractive index layer is the same as the coating liquid 1 for high refractive index layer except that 100 parts by mass of 20 mass% titanium dioxide sol (volume average particle diameter: 35 nm, rutile type titanium dioxide) is used instead of zirconia sol. Coating solution 2 was prepared.

(Preparation of high refractive index layer coating solution 3)
A coating solution 3 for a high refractive index layer was prepared in the same manner as the coating solution 2 for a high refractive index layer, except that the polymer (2) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 4)
A coating solution 4 for a high refractive index layer was prepared in the same manner as the coating solution 2 for a high refractive index layer, except that the polymer (3) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 5)
A coating solution 5 for a high refractive index layer was prepared in the same manner as the coating solution 2 for a high refractive index layer, except that the polymer (4) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 6)
A coating solution 6 for a high refractive index layer was prepared in the same manner as the coating solution 2 for a high refractive index layer, except that the polymer (5) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 7)
A coating solution 7 for a high refractive index layer was prepared in the same manner as the coating solution 2 for a high refractive index layer, except that the polymer (6) was used instead of the polymer (1).
(Preparation of high refractive index layer coating solution 8)
The above coating for a high refractive index layer except that the polymer (6) is used in place of the polymer (1) and 80 parts by mass of 20 mass% titanium dioxide sol (volume average particle diameter: 35 nm, rutile titanium dioxide) is used. In the same manner as Solution 2, a coating solution 8 for a high refractive index layer was prepared.
(Preparation of high refractive index layer coating solution 9)
The above coating for a high refractive index layer except that the polymer (6) is used instead of the polymer (1) and 50 parts by mass of 20% by mass titanium dioxide sol (volume average particle diameter: 35 nm, rutile titanium dioxide) is used. A coating solution 9 for a high refractive index layer was prepared in the same manner as Liquid 2.

(Preparation of high refractive index layer coating solution 10)
A coating solution 8 for a high refractive index layer was prepared in the same manner as the coating solution 2 for a high refractive index layer except that the polymer (7) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 11)
A high refractive index layer coating solution 9 was prepared in the same manner as the high refractive index layer coating solution 2 except that the polymer (8) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 12)
A coating solution 12 for a high refractive index layer was prepared in the same manner as the coating solution 2 for a high refractive index layer, except that the polymer (9) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 13)
Instead of polyvinyl alcohol, acid-treated gelatin (AP-270, weight average molecular weight 130,000, manufactured by Nippi Co., Ltd.) was used, except that the coating solution 2 for high refractive index layer 2 was used. A coating solution 13 was prepared.

(Preparation of high refractive index layer coating solution 14)
A high refractive index in the same manner as in the coating solution 2 for high refractive index layer, except that tamarind seed gum (TG-500, weight average molecular weight 500,000, manufactured by MRC Polysaccharide Co.) was used instead of polyvinyl alcohol. A layer coating solution 14 was prepared.

(Preparation of high refractive index layer coating solution 15)
The above coating solution for a high refractive index layer except that 100 parts by mass of a 5% by mass aqueous solution of polyvinyl alcohol (PVA210, weight average molecular weight 44,000, manufactured by Kuraray Co., Ltd.) was used instead of polyvinyl alcohol. In the same manner as in No. 2, a coating solution 15 for a high refractive index layer was prepared.

(Preparation of high refractive index layer coating solution 16)
A coating solution 13 for a high refractive index layer was prepared in the same manner as the coating solution 2 for a high refractive index layer, except that the polymer (10) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 17)
A high refractive index layer coating solution 14 was prepared in the same manner as the high refractive index layer coating solution 2 except that the polymer (11) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 18)
A coating solution 18 for a high refractive index layer was prepared in the same manner as the coating solution 2 for a high refractive index layer except that the polymer (12) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 19)
Except not using polyvinyl alcohol, the coating liquid 19 for high refractive index layers was prepared like the said coating liquid 7 for high refractive index layers.

(Preparation of high refractive index layer coating solution 20)
A high refractive index layer coating solution 20 was prepared in the same manner as the high refractive index layer coating solution 2 except that the polymer (13) was used instead of the polymer (1).

(Preparation of high refractive index layer coating solution 21)
The high refractive index layer except that the polymer (1) was not used and the amount of a 5% by mass aqueous solution of polyvinyl alcohol (PVA235, weight average molecular weight 150,000, manufactured by Kuraray Co., Ltd.) was changed to 200 parts by mass. In the same manner as the coating solution 2 for coating, a coating solution 21 for a high refractive index layer was prepared.

(Preparation of high refractive index layer coating solution 22)
For the high refractive index layer, except that 50 parts by mass of a 10% by mass aqueous solution of polyvinyl alcohol (PVA203, weight average molecular weight 13,000, manufactured by Kuraray Co., Ltd.) was used instead of polymer (1). A coating solution 17 for a high refractive index layer was prepared in the same manner as the coating solution 2.

(Preparation of low refractive index layer coating solution 1)
19 mass% colloidal silica (Snowtex AK, manufactured by Nissan Chemical Industries, Ltd., average particle size: 10 to 20 nm) 68 mass parts and 3 mass% boric acid aqueous solution 20 mass parts were heated to 40 ° C while stirring. Thereafter, 280 parts by mass of a 5% by mass aqueous solution of polyvinyl alcohol (PVA235, weight average molecular weight 150,000, manufactured by Kuraray Co., Ltd.) and 240 parts by mass of pure water were added and stirred for 10 minutes, and then a 5% by mass surfactant aqueous solution. (Cotamin 24P, manufactured by Kao Corporation) 0.64 parts by mass was added to prepare a low refractive index layer coating solution 1.

(Preparation of low refractive index layer coating solution 2)
Low refractive index layer coating solution 1 except that acid-treated gelatin (AP-270, weight average molecular weight 130,000, manufactured by Nippi Co., Ltd.) was used instead of polyvinyl alcohol, and 3% by weight boric acid aqueous solution was removed. In the same manner as above, a coating solution 2 for a low refractive index layer was prepared.

(Preparation of low refractive index layer coating solution 3)
The low refractive index is the same as the coating solution 2 for the low refractive index layer, except that tamarind seed gum (TG-500, weight average molecular weight 500,000, manufactured by MRC Polysaccharide Co.) is used instead of acid-treated gelatin. Layer coating solution 3 was prepared.

Example 1
[Production of light shielding film]
In the formation of the following high refractive index layer and low refractive index layer, in order to confirm the stability of the coating liquid, the above prepared high refractive index layer coating liquid and low refractive index layer coating liquid were each kept at 45 ° C. However, it was used after being stirred and stored for 24 hours.

[Formation of Low Refractive Index Layer 1]
While drying the above prepared coating solution 1 for a low refractive index layer at 45 ° C., on a 50 μm thick polyethylene terephthalate film (Toyobo Co., Ltd., A4300, double-sided easy adhesion layer) heated to 45 ° C. The film is coated using a wire bar under the condition that the film thickness is 175 nm, and then set by blowing cold air for 1 minute under the condition that the film surface is 15 ° C. or lower, and then dried by blowing hot air of 80 ° C. Thus, the low refractive index layer 1 was formed.

[Formation of High Refractive Index Layer 1]
Next, on the condition that the film thickness upon drying is 135 nm on the low refractive index layer 1 heated to 45 ° C. while keeping the prepared coating solution 1 for the high refractive index layer at 45 ° C. A high refractive index layer 1 was formed by coating using a bar, and then setting by blowing cold air for 1 minute under conditions where the film surface was 15 ° C. or lower, and then blowing hot air at 80 ° C. .

  On the formed high refractive index layer 1, the same operations as described in [Formation of low refractive index layer 1] and [Formation of high refractive index layer 1] are repeated, and the low refractive index layer 1 / After further stacking 5 units composed of the high refractive index layer 1 and forming an alternate laminated film composed of a total of 6 units (12 layers in total), the low refractive index layer 1 is further laminated on the top layer, A light shielding film 1 (total thickness of the film: 52 μm) was produced. The film surface pH was adjusted to 7.2. Acetic acid and aqueous ammonia were used to adjust the pH.

Example 2
A light shielding film 2 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 2 was used instead of the high refractive index layer coating solution 1 in Example 1.

Example 3
In Example 1, the light shielding film 3 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 3 was used instead of the high refractive index layer coating solution 1.

Example 4
A light shielding film 4 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 4 was used instead of the high refractive index layer coating solution 1 in Example 1.

Example 5
In Example 1, the light shielding film 5 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 5 was used instead of the high refractive index layer coating solution 1.

Example 6
In Example 1, a light shielding film 6 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 6 was used instead of the high refractive index layer coating solution 1.

Example 7
In Example 1, a light shielding film 7 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 7 was used instead of the high refractive index layer coating solution 1.

Example 8
A light shielding film 8 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 8 was used instead of the high refractive index layer coating solution 1 in Example 1.

Example 9
In Example 1, a light shielding film 9 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 9 was used instead of the high refractive index layer coating solution 1.

Example 10
In Example 1, the light shielding film 10 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 10 was used instead of the high refractive index layer coating solution 1.

Example 11
In Example 1, the light shielding film 11 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 11 was used instead of the high refractive index layer coating solution 1.

Example 12
In Example 1, a light shielding film 12 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 12 was used instead of the high refractive index layer coating solution 1.

Example 13
In Example 1, the coating solution 13 for the high refractive index layer was used instead of the coating solution 1 for the high refractive index layer, and the coating solution 2 for the low refractive index layer was used instead of the coating solution 1 for the low refractive index layer. Except for the above, a light shielding film 13 was produced in the same manner as in Example 1.

Example 14
In Example 1, the high refractive index layer coating solution 14 was used instead of the high refractive index layer coating solution 1, and the low refractive index layer coating solution 3 was used instead of the low refractive index layer coating solution 1. Except for the above, a light shielding film 14 was produced in the same manner as in Example 1.

Comparative Example 1
A comparative light shielding film 1 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 15 was used instead of the high refractive index layer coating solution 1 in Example 1.

Comparative Example 2
A comparative light shielding film 2 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 16 was used instead of the high refractive index layer coating solution 1 in Example 1.

Comparative Example 3
A comparative light shielding film 3 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 17 was used instead of the high refractive index layer coating solution 1 in Example 1.

Example 15
In Example 1, a light shielding film 15 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 18 was used instead of the high refractive index layer coating solution 1.

Comparative Example 4
A comparative light shielding film 4 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 19 was used instead of the high refractive index layer coating solution 1 in Example 1.

Comparative Example 5
A comparative light shielding film 5 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 20 was used instead of the high refractive index layer coating solution 1 in Example 1.

Comparative Example 6
A comparative light shielding film 6 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 21 was used instead of the high refractive index layer coating solution 1 in Example 1.

Comparative Example 7
In Example 1, the comparative light shielding film 7 was produced in the same manner as in Example 1 except that the high refractive index layer coating solution 22 was used instead of the high refractive index layer coating solution 1.

(Evaluation of light shielding film)
About each produced said light-shielding film, the following characteristic value was measured.

(Measurement of visible light transmittance and near infrared transmittance)
Using a spectrophotometer (U-4000 type, manufactured by Hitachi, Ltd.), the transmittance in the region of 800 to 1400 nm of each light shielding film was measured, the average value was obtained, and this was determined as the near infrared transmittance ( %). The smaller this value, the higher the near infrared blocking property.

  Moreover, the transmittance | permeability in 550 nm was measured and it was set as the visible light transmittance | permeability (%).

(Evaluation of uniformity)
In the above (measurement of visible light transmittance and near-infrared reflectance), the near-infrared transmittance (%) is measured at 10 points, and in this case, the variation in near-infrared transmittance is 5% or less. The case where the variation in near-infrared transmittance is greater than 5% and 15% or less is denoted by “Δ”, and the case where the variation in near-infrared transmittance is greater than 15% is denoted by “X”.

  Table 1 shows the results of near-infrared transmittance, visible light transmittance, and uniformity.

  As is clear from the results in Table 1, the light shielding films 1 to 15 of the present invention have a significantly lower near-infrared transmittance than the comparative light shielding films 1 to 7 of the comparative examples (in the near-infrared shielding property). It can be seen that the visible light transmittance is significantly high (excellent visible light transmittance).

  In addition, the light shielding films 7 to 9 of the present invention can increase the ratio of metal oxide particles in the high refractive index layer coating solution, and lower the near infrared transmittance without affecting the uniformity (near red). It can be seen that it is possible to improve the outer blocking ability. In particular, the comparative light shielding film 4 has minute cracks in the coating, and the comparative light shielding films 5 to 7 have film surface quality that is intensely aggregated in the high refractive index layer and cannot be evaluated. did.

Example 2
[Production of near-infrared shield]
Using the light shielding films 1 to 15 produced in Examples 1 to 15, near infrared reflectors 1 to 15 were produced as follows. That is, using the light shielding films 1 to 6 → 15 in which an adhesive layer is provided as follows on a transparent acrylic resin plate having a thickness of 5 mm and 20 cm × 20 cm, respectively, the near infrared shielding bodies 1 to 6 → 15 was produced.

  First, 60 parts by mass of ethyl acetate and 20 parts by mass of toluene were mixed, and further 20 g of acrylic adhesive (Arontack M-300: manufactured by Toagosei Co., Ltd.) was added and mixed by stirring to prepare an adhesive coating solution. Next, as described below, an adhesive layer was applied to the separator film, and then bonded to the light shielding films 1 to 15, respectively. In addition, as a separator film, a 25-micrometer-thick polyester film (Therapy: Toyo Metallizing Co., Ltd. product) was used. On the separator film, the adhesive coating solution prepared above was applied with a wire bar and dried at 80 ° C. for 2 minutes to prepare a film with an adhesive layer. Then, the adhesion layer surface of the film with an adhesion layer was bonded to the infrared reflective layer surface of the said light shielding film with the bonding machine. At this time, the tension at the time of bonding on the infrared reflective layer film side was 10 kg / m, and the tension at the time of bonding of the film with the adhesive layer was 30 kg / m.

[Evaluation]
The produced near-infrared shields 1 to 15 can be easily used in spite of a large size, and confirm excellent light reflectivity by using the light shielding film of the present invention. I was able to.

Claims (5)

A light shielding film having at least one unit in which a high refractive index layer and a low refractive index layer are alternately laminated on a support,
The high refractive index layer is
1) The following general formula (1):

In the general formula (1), R ¹ represents a hydrogen atom or a monovalent metal atom; R ² represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl having 6 to 12 carbon atoms. R ³ represents a hydrogen atom or a methyl group; X represents a single bond or a divalent linking group containing a carbonyl group; and m is an integer of 0 to 3.
A water-soluble polymer (1) having a weight average molecular weight of 1000 to 30,000, having a structural unit represented by
2) a light-shielding film comprising a water-soluble polymer (2) having a weight average molecular weight of 50,000 or more; and 3) metal oxide particles.   The light shielding film according to claim 1, wherein the water-soluble polymer (1) further has a structural unit having a hydroxyl group (-OH) or an amide group in the side chain in the molecule.   The light shielding film of Claim 1 or 2 whose content rate of the structural unit represented by the said General formula (1) in the said water-soluble polymer (1) is 3-80 mol%.   The light shielding film according to claim 1, which is a near-infrared shielding film.   The infrared shielding body which provides the light shielding film of any one of Claims 1-4 on the at least one surface of a base | substrate.