JP5724413B2 - Near-infrared reflective film, method for producing the same, and near-infrared reflector - Google Patents

Description

  The present invention relates to a near-infrared reflective film excellent in near-infrared reflectivity, visible light transmittance and durability, a method for producing the same, and a near-infrared reflector.

  In recent years, with increasing interest in energy saving measures, from the viewpoint of reducing the load on cooling equipment, there is an increasing demand for near-infrared reflective films that can be attached to window glass of buildings and vehicles to block the transmission of solar heat rays. It is coming.

  As a method for forming a near-infrared reflective film, a dry film forming method such as a vapor deposition method or a sputtering method is mainly used for a laminated film having a structure in which a high refractive index layer and a low refractive index layer are alternately laminated. There has been proposed a method of forming them. 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 near-infrared reflective film using a wet coating method instead of the dry film forming method having the above-described problems is known.

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

  However, there is a problem that the target film thickness cannot be obtained uniformly because the viscosity is low in an organic solvent system, and further, the film spreads and dries when laminated.

  Furthermore, a method of forming a film by light irradiation or the like with a composition containing titanium oxide fine particles, an organic silicon compound and a polyfunctional acrylic compound as main components has been proposed (for example, see Patent Document 3). In the above configuration, since a hard film is produced by UV irradiation or the like, there is a problem that a surface treatment or the like is required when further laminating and coating, and the interface is disturbed.

JP-A-8-110401 JP 2004-123766 A JP 2001-164117 A

  The present invention has been made in view of the above problems, and has as its object the near infrared reflective film having high near infrared reflectance and visible light transmittance, excellent film thickness uniformity and haze, and the near infrared. It is providing the near-infrared reflector which has a reflecting film.

  The above object of the present invention is achieved by the following configurations.

Near-red having at least one unit composed of a high refractive index layer and a low refractive index layer on a substrate, and having a refractive index difference of 0.1 or more between the high refractive index layer and the low refractive index layer In the external reflection film, at least one of the high refractive index layer and the low refractive index layer contains a metal oxide particle whose surface is coated with low molecular gelatin , and a water solution containing a structural unit represented by the following general formula (I) A near-infrared reflective film comprising a functional polymer A.

(In the formula, R represents a hydrogen atom or a methyl group, Q represents —C (═O) O—, or —C (═O) NRa—, Ra represents a hydrogen atom or an alkyl group, and A represents a substituted group). or unsubstituted alkylene group or, _- (CH 2 _CHRbO) .Rb representing the x-CH 2 CHRb- represents a hydrogen atom or an alkyl group, x represents the average number of repeating units).

2 . 2. The near-infrared reflective film as described in 1 above, further comprising a water-soluble polymer B selected from a polymer having a reactive functional group, an inorganic polymer, a thickening polysaccharide and gelatin.

3 . The near-infrared reflective film as described in 1 or 2 above, further comprising a cationic surfactant.

4 . 4. The method for producing a near-infrared reflective film according to any one of 1 to 3 , wherein at least two layers are coated simultaneously.

5 . The near-infrared reflective film obtained by the manufacturing method of the near-infrared reflective film of any one of said 1-3 or the said near-infrared reflective film of said 4 is provided in the at least one surface side of a base | substrate. A near-infrared reflector, comprising:

  According to the present invention, a near-infrared reflective film having high near-infrared reflectance and visible light transmittance, excellent film thickness uniformity and haze, and a near-infrared reflector having the near-infrared reflective film are provided. did it.

  As a result of intensive studies in view of the above problems, the present inventor has at least one unit composed of a high refractive index layer and a low refractive index layer on a substrate, and the high refractive index layer and the low refractive index In the near-infrared reflective film having a refractive index difference of 0.1 or more with respect to the refractive index layer, at least one of the high refractive index layer and the low refractive index layer is coated with metal oxide particles, and the general formula The near-infrared reflective film containing the water-soluble polymer A containing the structural unit represented by (I) has a high near-infrared reflectance and visible light transmittance, and a near-infrared excellent in film thickness uniformity and haze. It has been found that a reflection film and a near-infrared reflector having the near-infrared reflection film can be realized, and the present invention has been achieved.

  That is, by adding the water-soluble polymer A containing the structural unit represented by the general formula (I) to the metal oxide particles coated on the surface, the fine particles and the like do not aggregate in the state of the coating solution, and the temperature is increased. It was found that the coating film thickness can be made uniform by reacting and changing to a gel state when water is volatilized.

  Hereinafter, the component of the near-infrared reflective film of this invention, the form for implementing this invention, etc. are demonstrated in detail.

《Near-infrared reflective film》
The near-infrared reflective film of the present invention has at least one unit composed of a high refractive index layer and a low refractive index layer on a substrate, and at least one layer of the high refractive index layer and the low refractive index layer. Is a near-infrared reflective film characterized in that it contains a metal oxide particle coated with a surface and a water-soluble polymer A containing the structural unit represented by the general formula (I). The basic optical characteristics of the reflective film are characterized in that the refractive index difference between the high refractive index layer and the low refractive index layer is 0.1 or more.

  Moreover, as a transmittance | permeability of visible light region shown by JISR3106-1998, it is preferable to have the area | region which exceeds 50% in the area | region of a wavelength 900-1400nm 50% or more.

  In general, in the near-infrared reflective film, the larger the difference in refractive index between the high refractive index layer and the low refractive index layer, the better from the viewpoint that the infrared reflectance can be increased with a small number of layers. Preferably, at least one of the units composed of the high refractive index layer and the low refractive index layer has a difference in refractive index between the adjacent high refractive index layer and low refractive index layer of 0.1 or more, preferably Is 0.3 or more, particularly preferably 0.4 or more.

  The reflectance in the specific wavelength region is determined by the difference in refractive index between two adjacent layers and the number of stacked layers, and the larger the difference in refractive index, the same reflectance can be obtained with a smaller number of layers. The refractive index difference and the required number of layers can be calculated using commercially available optical design software. For example, in order to obtain an infrared reflectance of 90% or more, if the refractive index difference is smaller than 0.1, the number of layers exceeding 100 layers is required, which not only decreases productivity but also scattering at the laminated interface. Becomes larger, the transparency is lowered, and it becomes very difficult to manufacture without failure. From the viewpoint of improving reflectivity and reducing the number of layers, there is no upper limit to the difference in refractive index, but the limit is substantially about 1.40.

<< Configuration of near-infrared reflective film >>
Next, the basic configuration of the high refractive index layer and the low refractive index layer in the near-infrared reflective film of the present invention will be described.

  In the near-infrared reflective film of the present invention, the substrate is composed of a high refractive index layer and a low refractive index layer, and the refractive index difference between the high refractive index layer and the low refractive index layer is 0.1 or more. A configuration in which at least one unit is laminated may be used. However, the preferred number of layers of the high refractive index layer and the low refractive index layer is, from the above viewpoint, the range of the total number of layers is 100 layers or less, that is, 50 No more than units, more preferably no more than 40 layers (20 units) and even more preferably no more than 20 layers (10 units).

  Moreover, in the near-infrared reflective film of this invention, as a preferable refractive index of a high refractive index layer, it is 1.80-2.50, More preferably, it is 1.90-2.20. Moreover, as a preferable refractive index of a low-refractive-index layer, it is 1.10-1.60, More preferably, it is 1.30-1.50.

  In the near-infrared reflective film of the present invention, a layer configuration in which the layer adjacent to the substrate is a low refractive index layer containing silicon oxide and the outermost layer is also a low refractive index layer containing silicon oxide is preferable.

  In the present invention, the refractive indexes of the high refractive index layer and the low refractive index layer can be determined according to the following method.

  A sample in which each refractive index layer for measuring a refractive index is coated as a single layer on a substrate is prepared, and the sample is cut into 10 cm × 10 cm, and then the refractive index is obtained according to the following method.

  Using a U-4000 type (manufactured by Hitachi, Ltd.) as a spectrophotometer, the back side on the measurement side of each sample is roughened, and then light absorption is performed with a black spray to reflect light on the back side. In this case, the reflectance of the visible light region (400 to 700 nm) is measured at 25 points under the condition of regular reflection at 5 degrees to obtain an average value, and the average refractive index is obtained from the measurement result.

《NIR reflection film components》
Hereinafter, details of each component of the near-infrared reflective film of the present invention will be described.

〔Base material〕
The substrate applied to the near-infrared reflective film of the present invention is preferably a film support, and the film support may be transparent or opaque, and various resin films may be used. Polyolefin films (polyethylene, polypropylene, etc.), polyester films (polyethylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride, cellulose acetate, etc. can be used, and polyester films are preferred.

  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 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 components, from the viewpoints of transparency, mechanical strength, dimensional stability, etc., as dicarboxylic acid components, terephthalic acid, 2,6-naphthalenedicarboxylic acid, diol components as ethylene glycol and 1 Polyester having 1,4-cyclohexanedimethanol as the main constituent is preferred. Among these, polyesters mainly composed of polyethylene terephthalate and polyethylene naphthalate, copolymerized 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.

  The thickness of the film support according to the present invention is preferably 10 to 300 μm, more preferably 20 to 150 μm. The film support of the present invention may be a laminate of two sheets, and in this case, the type may be the same or different.

[Metal oxide particles]
At least one of the high-refractive index layer and the low-refractive index layer according to the present invention is characterized by containing metal oxide particles coated on the surface. Preferably, the high-refractive index layer and the low-refractive index layer include It is a preferred embodiment that the surface contains metal oxide particles coated.

  Examples of the metal oxide according to the present invention include titanium dioxide, zirconium oxide, zinc oxide, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, lead titanate, red lead, yellow lead, zinc yellow, chromium oxide. And ferric oxide, iron black, copper oxide, magnesium oxide, magnesium hydroxide, strontium titanate, yttrium oxide, niobium oxide, europium oxide, lanthanum oxide, zircon, and tin oxide.

  50-95 mass% is preferable and, as for content of the metal oxide in a high refractive index layer and a low refractive index layer, 60-90 mass% is more preferable. By setting the content of the metal oxide to 50% by mass or more, it becomes easy to increase the refractive index difference between the high refractive index layer and the low refractive index layer, and the content of the metal oxide is set to 95% by mass or less. Thereby, the flexibility of the film is obtained, and it becomes easy to form a near-infrared reflective film.

  In each refractive index layer, the mass ratio between the metal oxide particles and the water-soluble polymer A containing the structural unit represented by the general formula (I), which is one of the binders constituting each layer, is 0.1. It is preferable that it is the range of -20, More preferably, it is 0.5-10.

As the metal oxide of the metal oxide particles used for forming the high refractive index layer according to the present invention, TiO ₂ , ZnO, and ZrO ₂ are preferable, and TiO ₂ is more preferable from the viewpoint of the stability of the metal oxide particle-containing composition. preferable. Of TiO _2, the rutile type is preferable because the catalyst activity is low and the weather resistance of the high refractive index layer and the adjacent layer is high, and the refractive index is high.

  In the present invention, it is desirable to use a titanium dioxide sol for the preparation of a coating solution for forming a high refractive index layer. Examples of methods for preparing the titanium dioxide sol include JP-A-63-17221 and JP-A-7-819. Nos. 9, 9-165218, 11-43327, etc. can be referred to.

  As other methods for preparing titanium dioxide sol, for example, refer to JP-A-63-17221, JP-A-7-819, JP-A-9-165218, and JP-A-11-43327. it can.

  The preferable primary particle diameter of the titanium dioxide fine particles is 4 to 50 nm, and more preferably 4 to 30 nm.

  In the low refractive index layer according to the present invention, as the metal oxide particles, silicon dioxide particles are preferably used, and acidic colloidal silica sol is particularly preferably used.

  The silicon dioxide particles according to the present invention preferably have an average particle size of 100 nm or less. 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 volume average particle diameter of the titanium oxide particles according to the present invention is a method of observing the particles themselves using a laser diffraction scattering method, a dynamic light scattering method, or an electron microscope, or appears on the cross section or surface of the refractive index layer. The particle diameter of 1,000 arbitrary particles is measured by a method of observing the particle image with an electron microscope, and particles having particle diameters of d1, d2,. ··························· In a group of nk titanium oxide particles, where the volume per particle is vi, the volume average particle diameter mv = {Σ (vi · di)} / {Σ (vi) } The average particle size weighted by the volume represented by

  In the present invention, the metal oxide fine particles cover the surface.

  The compound that coats the surface of the metal oxide fine particles may be, for example, a polyvalent metal compound such as polyaluminum chloride or zirconium salt in the case of adjusting the charge, aminocarboxylic acids, aminopolycarboxylic acids, pyridine derivatives and collagen. Peptides, low molecular gelatin and the like are also preferable.

  In the present invention, low molecular weight gelatin or collagen peptide having a weight average molecular weight of 30,000 or less is most preferable. However, in order to reduce shock when low molecular weight gelatin or the like is added, the surface of the metal oxide fine particles is preliminarily coated. It is also possible to coat with two or more compounds such as coating with aluminum chloride or the like.

<Low molecular weight gelatin, collagen peptide>
The low molecular weight gelatin or collagen peptide according to the present invention preferably has a weight average molecular weight of 30,000 or less.

  The collagen peptide as used in the present invention is defined as a protein obtained by subjecting gelatin to low molecular weight treatment so that sol-gel change is not expressed.

  The low molecular weight gelatin or collagen peptide according to the present invention has a weight average molecular weight of 30,000 or less, more preferably 2,000 to 30,000, and particularly preferably 5,000 to 25,000. .

  The weight average molecular weight of low molecular weight gelatin or collagen peptide can be measured by gel filtration chromatography. Low molecular weight gelatin or collagen peptides are hydrolyzed by adding gelatin-degrading enzyme to a commonly used polymer gelatin aqueous solution having a weight average molecular weight of about 100,000, hydrolyzing by adding acid or alkali, and atmospheric pressure. It can be obtained by thermal decomposition by heating under or under pressure, decomposition by ultrasonic irradiation, or a combination of these methods.

  More specifically, the low molecular weight gelatin and collagen peptide according to the present invention can be prepared as follows.

  Generally used high molecular gelatin having a weight average molecular weight of 100,000 or more is dissolved in water, and gelatinolytic enzyme is added to enzymatically decompose gelatin molecules. For this method, see R.A. J. et al. Cox. Reference can be made to the description of Photographic Gelatin II, Academic Press, London, 1976, P233-251, P335-P346. In this case, since the binding position where the enzyme decomposes is determined, low molecular weight gelatin having a relatively narrow molecular weight distribution can be obtained, which is preferable. In this case, the longer the enzymatic decomposition time, the lower the molecular weight. In addition, there is a method of heating in a low pH (pH 1 to 3) or high pH (pH 10 to 12) atmosphere for hydrolysis. When the weight average molecular weight is 30,000 or less, the effect of the present invention is enhanced. Gelatin and collagen peptides having a weight average molecular weight of 2000 or more are easy to produce.

  In the low molecular gelatin or collagen peptide according to the present invention, in the preparation step of the low molecular gelatin or collagen peptide, the high molecular gelatin having a weight average molecular weight of 100,000 or more used as a raw material is sufficiently decomposed, and its content is In order to optimally perform enzymatic degradation of high molecular gelatin molecules so as to be 1.0% by mass or less, it is preferable to appropriately set conditions such as the type and amount of gelatinolytic enzyme, temperature and time during enzymatic degradation. .

<Surface coating method of metal oxide fine particles>
Examples of the method for coating the surface of the metal oxide fine particles include a method in which a surface coating material is added to the dispersion of the metal oxide fine particles and heated as necessary, or an acid or alkali is added. . Specifically, for example, the temperature of the titanium oxide particle sol (metal oxide fine particles) is raised to 50 ° C. while stirring, and then low molecular gelatin (surface coating material) is added and stirred for 30 minutes. Cover with low molecular gelatin.

[Water-soluble polymer A containing a structural unit represented by formula (I)]
The present invention is characterized in that at least one of the high refractive index layer and the low refractive index layer contains the water-soluble polymer A containing the structural unit represented by the general formula (I).

  In the present invention, the water-soluble polymer A means a polymer that is water-soluble and dissolves 0.001 g or more in 100 g of water at 25 ° C. The dissolution can be measured with a haze meter or a turbidimeter.

  The water-soluble polymer A according to the present invention has a structure including the structural unit represented by the general formula (I), and may be a homopolymer represented by the general formula (I). The components may be copolymerized. When copolymerizing other components, the structural unit represented by the general formula (I) is preferably contained in an amount of 10 mol% or more, more preferably 30 mol% or more, and more preferably 50 mol% or more. More preferably.

  Moreover, it is preferable that 40-80 mass% of water-soluble polymers A are contained in a layer, and it is more preferable that it is 50-70 mass%.

In the general formula (I), R represents a hydrogen atom or a methyl group, and Q represents —C (═O) O— or —C (═O) NRa—. Ra represents a hydrogen atom or an alkyl group, A represents a substituted or unsubstituted alkylene group, or — (CH ₂ CHRbO) x —CH ₂ CHRb—. Rb represents a hydrogen atom or an alkyl group, and x represents the average number of repeating units.

  As the alkyl group represented by Ra, for example, a linear or branched alkyl group having 1 to 5 carbon atoms is preferable, and a methyl group is more preferable. Moreover, these alkyl groups may be substituted with a substituent. Examples of these substituents include alkyl groups, cycloalkyl groups, aryl groups, heterocycloalkyl groups, heteroaryl groups, hydroxyl groups, halogen atoms, alkoxy groups, alkylthio groups, arylthio groups, cycloalkoxy groups, aryloxy groups, acyls. Group, alkylcarbonamide group, arylcarbonamide group, alkylsulfonamide group, arylsulfonamide group, ureido group, aralkyl group, nitro group, alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, alkylcarbamoyl group, aryl Rucarbamoyl group, alkylsulfamoyl group, arylsulfamoyl group, acyloxy group, alkenyl group, alkynyl group, alkylsulfonyl group, arylsulfonyl group, alkyloxysulfonyl group, Lumpur oxysulfonyl group, an alkylsulfonyloxy group, an aryl sulfonyloxy group. Of these, a hydroxyl group and an alkyloxy group are preferable.

  Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

  The alkyl group may have a branch, and the number of carbon atoms is preferably 1 to 20, more preferably 1 to 12, and still more preferably 1 to 8. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, t-butyl group, hexyl group, octyl group and the like.

  The cycloalkyl group preferably has 3 to 20 carbon atoms, more preferably 3 to 12, and still more preferably 3 to 8. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

  The alkoxy group may have a branch, and the number of carbon atoms is preferably 1 to 20, more preferably 1 to 12, still more preferably 1 to 6, and further preferably 1 to 4. Most preferably. Examples of the alkoxy group include a methoxy group, an ethoxy group, a 2-methoxyethoxy group, a 2-methoxy-2-ethoxyethoxy group, a butyloxy group, a hexyloxy group, and an octyloxy group, and preferably an ethoxy group.

  The number of carbon atoms of the alkylthio group may be branched, and the number of carbon atoms is preferably 1-20, more preferably 1-12, even more preferably 1-6, Most preferably, it is 1-4. Examples of the alkylthio group include a methylthio group and an ethylthio group.

  The arylthio group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the arylthio group include a phenylthio group and a naphthylthio group.

  The cycloalkoxy group preferably has 3 to 12 carbon atoms, and more preferably 3 to 8 carbon atoms. Examples of the cycloalkoxy group include a cyclopropoxy group, a cyclobutoxy group, a cyclopentyloxy group, and a cyclohexyloxy group.

  The aryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the aryl group include a phenyl group and a naphthyl group.

  The aryloxy group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the aryloxy group include a phenoxy group and a naphthoxy group.

  The heterocycloalkyl group preferably has 2 to 10 carbon atoms, and more preferably 3 to 5 carbon atoms. Examples of heterocycloalkyl groups include piperidino groups, dioxanyl groups and 2-morpholinyl groups.

  The heteroaryl group preferably has 3 to 20 carbon atoms, and more preferably 3 to 10 carbon atoms. Examples of the heteroaryl group include a thienyl group and a pyridyl group.

  The acyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of acyl groups include formyl, acetyl and benzoyl groups.

  The alkylcarbonamide group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the alkylcarbonamide group include an acetamide group.

  The arylcarbonamide group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the arylcarbonamide group include a benzamide group.

  The alkylsulfonamide group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the sulfonamido group include a methanesulfonamido group.

  The arylsulfonamide group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the arylsulfonamide group include a benzenesulfonamide group and p-toluenesulfonamide group.

  The aralkyl group preferably has 7 to 20 carbon atoms, and more preferably 7 to 12 carbon atoms. Examples of aralkyl groups include benzyl, phenethyl and naphthylmethyl groups.

  The alkoxycarbonyl group preferably has 1 to 20 carbon atoms, more preferably 2 to 12 carbon atoms. Examples of the alkoxycarbonyl group include a methoxycarbonyl group.

  The aryloxycarbonyl group preferably has 7 to 20 carbon atoms, and more preferably 7 to 12 carbon atoms. Examples of the aryloxycarbonyl group include a phenoxycarbonyl group.

  The number of carbon atoms in the aralkyloxycarbonyl group is preferably 8-20, and more preferably 8-12. Examples of the aralkyloxycarbonyl group include a benzyloxycarbonyl group.

  The acyloxy group preferably has 1 to 20 carbon atoms, more preferably 2 to 12 carbon atoms. Examples of the acyloxy group include an acetoxy group and a benzoyloxy group.

  The alkenyl group has preferably 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of alkenyl groups include vinyl, allyl and isopropenyl groups.

  The alkynyl group preferably has 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of alkynyl groups include ethynyl groups.

  The alkylsulfonyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the alkylsulfonyl group include a methylsulfonyl group and an ethylsulfonyl group.

  The arylsulfonyl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the arylsulfonyl group include a phenylsulfonyl group and a naphthylsulfonyl group.

  The alkyloxysulfonyl group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the alkyloxysulfonyl group include a methoxysulfonyl group and an ethoxysulfonyl group.

  The aryloxysulfonyl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the aryloxysulfonyl group include a phenoxysulfonyl group and a naphthoxysulfonyl group.

  The alkylsulfonyloxy group preferably has 1 to 20 carbon atoms, and more preferably 1 to 12 carbon atoms. Examples of the alkylsulfonyloxy group include a methylsulfonyloxy group and an ethylsulfonyloxy group.

  The arylsulfonyloxy group preferably has 6 to 20 carbon atoms, and more preferably 6 to 12 carbon atoms. Examples of the arylsulfonyloxy group include a phenylsulfonyloxy group and a naphthylsulfonyloxy group. The substituents may be the same or different, and these substituents may be further substituted.

In general formula (I), A is a substituted or unsubstituted alkylene group, or _- represents CHRb- a _{(CH 2 CHRbO) x-CH} 2. Rb represents a hydrogen atom or an alkyl group, and x represents the average number of repeating units.

  As an alkylene group, C1-C5 is preferable, for example, More preferably, they are an ethylene group and a propylene group. These alkylene groups may be substituted with the substituent described above.

  Rb represents a hydrogen atom or an alkyl group, and the alkyl group is preferably, for example, a linear or branched alkyl group having 1 to 5 carbon atoms, and more preferably a methyl group. Moreover, these alkyl groups may be substituted with the above-mentioned substituent. Furthermore, x represents the average number of repeating units, preferably 0 to 100, more preferably 0 to 10. The number of repeating units has a distribution, and the notation indicates an average value and may be expressed with one decimal place.

  In the following, typical specific examples of the structural unit represented by formula (I) are shown, but the present invention is not limited thereto.

[Water-soluble polymer B]
In the present invention, in addition to the water-soluble polymer A in which at least one of the high-refractive index layer and the low-refractive index layer includes a metal oxide particle covering the surface and the structural unit represented by the general formula (I). Furthermore, it is preferable to contain a water-soluble polymer B selected from a polymer having a reactive functional group, an inorganic polymer, a thickening polysaccharide and gelatin. The water-soluble polymer B is particularly preferably gelatin.

  The water-soluble polymer B according to the present invention refers to a polymer compound that dissolves in an aqueous medium at 25 ° C. at 1% by mass or more, and preferably a polymer compound that dissolves in 3% by mass or more. The weight average molecular weight is preferably 1,000 to 200,000. Furthermore, 3,000-40,000 is more preferable.

  The concentration of the water-soluble polymer B in the coating solution for forming a high refractive index layer and the coating solution for forming a low refractive index layer according to the present invention is preferably 0.3 to 3.0% by mass, More preferably, it is in the range of -2.0% by mass.

  Hereinafter, the details of each water-soluble polymer B will be described.

(Polymer having reactive functional group)
Examples of the polymer having a reactive functional group applicable to the present invention include polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, acetic acid. Acrylic resin such as vinyl-acrylic acid ester copolymer or acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer Polymer, styrene-α-methylstyrene-acrylic acid copolymer, or styrene-acrylic acid resin such as styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer, styrene-sodium styrenesulfonate copolymer, Styrene-maleic acid copolymer, steel Lene-maleic anhydride copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic Examples thereof include vinyl acetate copolymers such as acid copolymers and salts thereof. Among these, particularly preferable examples include polyvinyl alcohol, polyvinyl pyrrolidones, and copolymers containing the same.

  The polyvinyl alcohol preferably used in the present invention includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, modified polyvinyl alcohol such as polyvinyl alcohol having a cation-modified terminal and anion-modified polyvinyl alcohol having an anionic group. 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 saponification degree is preferably 70 to 100%, particularly preferably 80 to 99.5%.

  Examples of the cation-modified polyvinyl alcohol include primary to tertiary amino groups and quaternary ammonium groups in the main chain or side chain of the polyvinyl alcohol as described in JP-A-61-110483. Polyvinyl alcohol, which is 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 cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, relative to vinyl acetate.

  Anion-modified polyvinyl alcohol is, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-2060888, as described in 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, and modified polyvinyl alcohol having a water-soluble group as described in JP-A-7-285265.

  Nonionic modified polyvinyl alcohol is, for example, a polyvinyl alcohol derivative obtained by adding a polyalkylene oxide group to a part of vinyl alcohol as described in JP-A-7-9758, and described in JP-A-8-25595. And a block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol. Polyvinyl alcohol can be used in combination of two or more, such as the degree of polymerization and the type of modification.

  In the present invention, a curing agent may be used when a polymer having a reactive functional group is used. When the polymer having a reactive functional group is polyvinyl alcohol, boric acid and a salt thereof described later and an epoxy curing agent are preferable.

(Inorganic polymer)
As one of the water-soluble polymers B according to the present invention, an inorganic polymer is preferably used. Among them, it is preferable to use an inorganic polymer such as a zirconium atom-containing compound or an aluminum atom-containing compound.

  Zirconium atom-containing compounds applicable to the present invention are those excluding zirconium oxide. 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 You Zirconium, 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 , Zirconium acetate, bis (acetylacetonato) dichloro zirconium and tris (acetylacetonato) chloro zirconium, and the like.

  Among these compounds, zirconyl chloride, zirconyl sulfate, sodium zirconyl sulfate, acidic zirconyl sulfate trihydrate, zirconyl nitrate, zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl ammonium acetate, zirconyl stearate are more preferable. Zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate and zirconyl chloride are preferable, and zirconyl ammonium carbonate, zirconyl chloride and zirconyl acetate are particularly preferable. Specific product names of the above compounds include Zircozole ZA-20 (Zirconyl Acetate) manufactured by Daiichi Rare Element Chemical Industry, Zircosol ZC-2 (Zirconyl Chloride) manufactured by Daiichi Rare Element Chemical Industry, First Rare Element Chemical Industry Zircosol ZN (zirconyl nitrate) and the like manufactured by the company are listed.

  Structural formulas of typical compounds among the inorganic polymers containing the zirconyl atom are shown below.

  However, s and t represent integers of 1 or more.

  The inorganic polymer containing a zirconyl 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. Specific product names of the above compounds include TAKIBAIN # 1500, which is polyaluminum chloride (PAC) manufactured by Taki Chemical, polyaluminum hydroxide (Paho) manufactured by Asada Chemical Co., and Purachem manufactured by Riken Green Co., Ltd. WT is listed, and various grades are available.

  The structural formula of Takibine # 1500 is shown below.

  However, s, t, and u represent an integer of 1 or more.

  1-100 mass parts is preferable with respect to 100 mass parts of metal oxide particles, and, as for the addition amount of the said inorganic polymer, 2-50 mass parts is more preferable.

(Thickening polysaccharide)
In the present invention, it is preferable to use a thickening polysaccharide as the water-soluble polymer B.

  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 saccharide polymer and has a characteristic that promotes a viscosity difference between a low temperature and a high temperature. Furthermore, the viscosity increase is caused by adding the thickening polysaccharide according to the present invention to the coating solution containing the metal oxide fine particles, and the viscosity increase range is such that the viscosity at 15 ° C. is 1.0 mPas. -A polysaccharide that causes an increase of s or more, preferably 5.0 mPa · s or more, and more preferably a polysaccharide having a viscosity increasing ability of 10.0 mPa · s or more.

  Examples of the thickening polysaccharide applicable to the present invention include β-1-4 glucan (eg, carboxymethylcellulose, carboxyethylcellulose, etc.), galactan (eg, agarose, agaropectin, etc.), galactomannoglycan (eg, locust). Bean gum, guaran, etc.), xyloglucan (eg, tamarind gum, etc.), glucomannoglycan (eg, salmon mannan, wood-derived glucomannan, xanthan gum, etc.), galactoglucomannoglycan (eg, softwood-derived glycan), Arabinogalactoglycans (for example, soybean-derived glycans, microbial-derived glycans, etc.), glucoraminoglycans (for example, gellan gum), glycosaminoglycans (for example, hyaluronic acid, keratan sulfate, etc.), alginic acid and alginate, agar Examples include natural polymer polysaccharides derived from red algae such as κ-carrageenan, λ-carrageenan, ι-carrageenan, and fercelerane, and are preferable from the viewpoint of not reducing the dispersion stability of the metal oxide fine particles coexisting in the coating solution. Are preferably those whose structural units do not have a carboxylic acid group or a sulfonic acid group. 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, tamarind seed gum known as xyloglucan whose main chain is glucose and side chain is glucose, guar gum known as galactomannan whose main chain is mannose and side chain is glucose, cationized guar gum, Hydroxypropyl guar gum, locust bean gum, tara gum, and arabinogalactan whose main chain is galactose and whose side chain is arabinose can be preferably used. In the present invention, tamarind, guar gum, cationized guar gum, and hydroxypropyl guar gum are particularly preferable.

  In the present invention, it is further preferable to use two or more types of thickening polysaccharides in combination.

  As content of thickening polysaccharide, 5-50 mass% is preferable and 10-40 mass% is more preferable. However, when used in combination with other water-soluble polymers or emulsion resins, it may be contained in an amount of 3% by mass or more. When there are few thickening polysaccharides, the film surface will be disordered at the time of drying of a coating film, and the tendency for transparency to deteriorate will become large. On the other hand, if the content is 50% by mass or less, the relative content of the metal oxide becomes appropriate, and it becomes easy to increase the difference in refractive index between the high refractive index layer and the low refractive index layer.

<gelatin>
Each refractive index layer according to the present invention most preferably contains gelatin as the water-soluble polymer B.

  As the gelatin applicable to the present invention, various gelatins that have been widely used in the field of silver halide photographic light-sensitive materials can be applied. For example, in addition to acid-processed gelatin and alkali-processed gelatin, production of gelatin is possible. Enzyme-treated gelatin and gelatin derivatives that undergo enzyme treatment in the process, that is, modified by treatment with a reagent that has an amino group, imino group, hydroxyl group, carboxyl group as a functional group in the molecule and a group obtained by reaction with it. You may have done. The general method for producing gelatin is well known and is described, for example, in T.W. H. James: The Theory of Photographic Process 4th. ed. Reference can be made to descriptions such as 1977 (Machillan) 55, Science Photo Handbook (above) 72-75 (Maruzen), Fundamentals of Photographic Engineering-Silver Salt Photographs 119-124 (Corona). Also, Research Disclosure Magazine Vol. 176, No. And gelatin described in Section IX of 17643 (December, 1978).

  In the present invention, it is preferable to use high molecular weight gelatin having a weight average molecular weight of 100,000 or more, and examples thereof include lime-processed gelatin, acid-processed gelatin, and alkali-processed gelatin.

  In the present invention, the weight average molecular weight of gelatin can be measured, for example, by gel permeation chromatography. The molecular weight distribution and the weight average molecular weight of gelatin can also be measured by a gel permeation chromatograph method (GPC method) which is a generally known method.

  Regarding the molecular weight of gelatin, see D.C. Lory and M.M. Vedrines, Proceedings of the 4th IAG Conference, Sept. 1983, p. 35, as described in Takashi Ohno, Hiroyuki Kobayashi, Shinya Mizusawa, Journal of the Japan Society of Photography, 47, 237 (1984), etc., the α component (molecular weight of about 100,000), which is a structural unit of collagen, and its two quantities In general, it comprises a β-component, a γ-component that is a trimer, a high-molecular amphoteric component that is a monomer, and a low-molecular-weight component in which these components are randomly cut.

  As the high molecular weight gelatin having a weight average molecular weight of 100,000 or more according to the present invention, among the above components, α component (molecular weight of about 100,000), which is a structural unit of collagen, and dimer and trimer thereof. Gelatin mainly composed of β component and γ component.

  Examples of the method for producing high molecular weight gelatin having a weight average molecular weight of 100,000 or more according to the present invention include the following methods.

  1) In the extraction operation during the production of gelatin, an extract in the early stage of extraction (low molecular weight component) is excluded by using an extract in the later stage of extraction.

  2) In the said manufacturing method, process temperature shall be less than 40 degreeC in the process from extraction to drying.

  3) The gelatin is dialyzed in cold water (15 ° C.).

  By using the above methods alone or in combination, a high molecular weight gelatin having a weight average molecular weight of 100,000 or more can be obtained.

(Curing agent)
In the present invention, it is preferable to use a curing agent in order to cure the water-soluble polymers A and B which are binders.

  The curing agent applicable to the present invention is not particularly limited as long as it causes a curing reaction with the water-soluble polymers A and B, but in general, a compound having a group capable of reacting with the water-soluble polymer or a water-soluble polymer. It is a compound that promotes the reaction between different groups of the polymer, and is appropriately selected according to the type of the water-soluble polymer. 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, glioxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy-1,3,5) -S-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum, carbodiimide compounds (Nisshinbo Carbodilite V-02, -02-L2, SV-02, etc.), oxazoline, and the like.

  Further, boric acid or a salt thereof can be used. Boric acid or a salt thereof refers to an oxygen acid having a boron atom as a central atom and a salt thereof, specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, and octaboron. Examples include acids and their salts.

  Boric acid having a boron atom as a curing agent and a salt thereof may be used as a single aqueous solution or as a mixture of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax.

  The total amount of the curing agent used is preferably 1 to 600 mg per 1 g of the water-soluble polymer A and B.

[Cationic surfactant]
At least one of the high refractive index layer and the low refractive index layer constituting the near-infrared reflective film of the present invention preferably contains a cationic surfactant from the viewpoint of coatability. The cationic surfactant can lower the surface tension with a small amount, and the physical properties of the high refractive index layer and the low refractive index layer are also improved. In particular, it is preferable to contain a quaternary ammonium salt cationic surfactant.

(Quaternary ammonium salt cationic surfactant)
The quaternary ammonium salt cationic surfactant applicable to the present invention is not particularly limited, but includes tetrabutylammonium chloride, tetraoctylammonium bromide (TOAB), lauryltrimethylammonium chloride, dilauryldimethylammonium chloride, dithiol. Stearyl ammonium chloride, distearyl dimethyl ammonium chloride, lauryl dihydroxyethyl methyl ammonium chloride, oleyl bis polyoxyethylene methyl ammonium chloride, lauroyl aminopropyl dimethyl ethyl ammonium etosulphate, lauroyl aminopropyl dimethyl hydroxyethyl ammonium perchlorate, alkylbenzene dimethyl ammonium chloride, Alkyltrimethylan Chloride and the like.

The quaternary ammonium salt cationic surfactant can also be obtained as a commercial product. For example, as a representative example, Coatamine 24P (C ₁₂ H ₂₅ N ^{+ (} CH ₃ ) ₃ Cl ⁻ ) manufactured by Kao Corporation Cotamine 86P (C ₁₈ H ₃₇ N ⁺ (CH ₃ ) ₃ Cl ⁻ ), Nissan Cation 2-ABT (C ₁₈ H ₃₇ N ⁺ C ₁₈ H ₃₇ (CH ₃ ) ₂ Cl ⁻ ) manufactured by NOF Corporation, The same Nissan cation 2-OLR (C ₁₈ H ₃₅ N ⁺ C ₁₈ H ₃₅ (CH ₃ ) ₂ Cl ⁻ ), NIKKOL CA3475V (C ₁₈ H ₃₇ N ⁺ C ₁₈ H ₃₇ (CH ₃ ) ₂ Cl manufactured by Nikko Chemicals) ^- )).

  The addition amount of each of the surfactants in the coating solution for forming a high refractive index layer and the coating solution for forming a low refractive index layer according to the present invention is, as a solid content, 0.1% when each coating solution is 100% by mass. The range is preferably in the range of 0010 to 0.10% by mass, and more preferably 0.0015 to 0.05% by mass.

In the present invention, among the quaternary ammonium salt cationic surfactants, dialkyl type quaternary ammonium salts are preferable. Specific examples of surfactant manufactured by NOF Corporation Nissan cation ^{_{2-ABT (C 18 H 37}} N + C 18 H 37 (CH 3) 2 Cl -), the Nissan cation _{2-OLR (C 18 H 35} N ^{_{+ C 18 H 35 (CH 3}} ) 2 Cl -), the Nissan cation ^{_{2-DB-500E (C 10}} H 21 N + C 10 H 21 (CH 3) 2 Cl -), Nikko Chemicals Co., Ltd. NIKKOL CA3475V ( C ₁₈ H ₃₇ N ⁺ C ₁₈ H ₃₇ (CH ₃ ) ₂ Cl ⁻ ) and the like. Furthermore, it is preferable that the carbon number of alkyl is C17 or less because the effect is high even in a small amount.

(Other additives)
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, JP-A-57-87989, and JP-A-60-72785. No. 61-146591, JP-A-1-95091 and JP-A-3-13376, etc., and various surfactants of anion, cation or nonion, and JP-A-59-42993 , 59-52689, 62-280069, 61-242871, and JP-A-4-219266, etc., optical brighteners, sulfuric acid, phosphoric acid, acetic acid, citric acid, water Known pH adjusters such as sodium oxide, potassium hydroxide and potassium carbonate, antifoaming agents, lubricants such as diethylene glycol, preservatives, antistatic agents, matting agents, etc. It may contain species additive.

[Method for producing near-infrared reflective film]
The near-infrared reflective film of the present invention is composed of a high refractive index layer and a low refractive index layer on a substrate, and is formed by laminating units. It is preferable to form a laminate by wet coating and drying alternately with the refractive index layer coating solution.

  As the coating method, for example, roll coating method, rod bar coating method, air knife coating method, spray coating method, curtain coating method, or each specification of US Pat. Nos. 2,761,419 and 2,761,791 The slide bead coating method using the hopper described in the book, the extrusion coating method, etc. are preferably used.

  In the present invention, it is preferable to apply at least two layers simultaneously. When the slide bead coating method is used, the viscosity of the high refractive index layer coating solution and the low refractive index layer coating solution in simultaneous multilayer coating is preferably in the range of 5 to 100 mPa · s, more preferably 10 to 10 mPa · s. The range is 50 mPa · s. Moreover, when using a curtain application | coating system, the range of 5-1200 mPa * s is preferable, More preferably, it is the range of 25-500 mPa * s.

  Further, the viscosity at 15 ° C. of the coating solution is preferably 100 mPa · s or more, more preferably 100 to 80,000 mPa · s, still more preferably 3,000 to 80,000 mPa · s, and most preferably 10 , 80 to 80,000 mPa · s.

  As a coating and drying method, the water-based high-refractive index layer coating solution and the low-refractive index layer coating solution are heated to 30 ° C. or more, and after coating, the temperature of the formed coating film is 1 to 15 ° C. It is preferably cooled once and dried at 10 ° C. or higher, and more preferably, the 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 formed coating-film uniformity.

[Application of near-infrared reflective film]
The near-infrared reflective film of the present invention can be applied to a wide range of fields. For example, pasting to facilities exposed to sunlight for a long time such as outdoor windows of buildings and automobile windows, film for window pasting such as heat ray reflecting film to give heat ray reflecting effect, film for agricultural greenhouse, etc. Used mainly for the purpose of improving weather resistance.

  In particular, the near-infrared reflective film according to the present invention is suitable for a member that is bonded to glass or a glass substitute resin base material directly or via an adhesive.

  The adhesive is installed so that the near-infrared reflective film is on the sunlight (heat ray) incident surface side when bonded to a window glass or the like. Moreover, when a near-infrared reflective film is pinched | interposed between a window glass and a base material, it can seal from surrounding gas, such as a water | moisture content, and is preferable for durability. Even if the near-infrared reflective film of the present invention is installed outdoors or outside the vehicle (for external application), it is preferable because of environmental durability.

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

  The adhesive preferably has durability against ultraviolet rays, and is preferably an acrylic adhesive or a silicone adhesive. Furthermore, an acrylic adhesive is preferable from the viewpoint of adhesive properties and cost. In particular, 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 resin used as an intermediate | middle layer of a laminated glass, or ethylene-vinyl acetate copolymer type resin. Specifically, plastic polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., Mitsubishi Monsanto Co., Ltd.), ethylene-vinyl acetate copolymer (manufactured by DuPont, Takeda Pharmaceutical Co., Ltd., duramin), modified ethylene-vinyl acetate copolymer (Mersen G, manufactured by Tosoh Corporation). In addition, you may add and mix | blend an ultraviolet absorber, an antioxidant, an antistatic agent, a heat stabilizer, a lubricant, a filler, coloring, an adhesion adjusting agent etc. suitably in a contact bonding layer.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<Production of near-infrared reflective film>
[Preparation of near-infrared reflective film 1]
(Preparation of coating solution 1 for low refractive index layer)
The following liquid was heated up to 45 degreeC, and it added in the following order, and prepared the coating liquid 1 for low refractive index layers.

  First, the temperature was raised to 45 ° C. while stirring the colloidal silica, and then a low molecular weight gelatin aqueous solution was added and stirred for 30 minutes to coat the surface of the colloidal silica particles with the low molecular weight gelatin. Subsequently, the homopolymer aqueous solution of the structural unit I-4 and pure water were added and stirred for 90 minutes, and then the surfactant aqueous solution was added to prepare the low refractive index layer coating solution 1.

Colloidal silica (20% by mass) 100 g
200g low molecular weight gelatin aqueous solution (5% by mass)
150 g of homopolymer aqueous solution of structural unit I-4 (5% by mass)
240g of pure water
Surfactant aqueous solution (CA-3475V, quaternary ammonium salt-based cationic surfactant, 5.0% by mass Nikko Chemicals) 0.64 g
The low molecular weight gelatin is a low molecular weight gelatin having a weight average molecular weight of 20,000 that has been hydrolyzed by alkali treatment. In addition, 0.1 g of Carbodilite V-02 (manufactured by Nisshinbo Co., Ltd.) was added as a crosslinking agent immediately before coating the coating solution 1 for a low refractive index layer on the substrate according to the following method.

(Formation of low refractive index layer 1)
On the 50 μm thick polyethylene terephthalate film (Toyobo A4300: double-sided easy-adhesion layer) heated to 45 ° C. while keeping the coating solution 1 for low refractive index layer at 45 ° C., the dry film thickness becomes 170 nm. The wire bar was applied as described above. Immediately thereafter, cold air was blown for 1 minute under conditions where the film surface was 15 ° C. or lower, and then the hot air of 80 ° C. was blown and dried to form the low refractive index layer 1 on the substrate.

(Preparation of coating solution 1 for high refractive index layer)
The following liquids were added and mixed in this order to prepare a high refractive index layer coating liquid 1.

  First, the titanium oxide particle sol was heated to 50 ° C. while stirring, and then low molecular gelatin was added and stirred for 30 minutes to coat the surface of the titanium oxide particles with low molecular gelatin. Subsequently, polymer gelatin and pure water were added and stirred for 90 minutes, and then a surfactant was added to prepare a high refractive index layer coating solution 1. This preparation method is referred to as preparation pattern A.

Titanium oxide particle sol (volume average particle size 35 nm, rutile type titanium oxide particles, 20% by mass) 60 g
125 g of low molecular weight gelatin (GelL1) aqueous solution (5.0% by mass)
High molecular weight gelatin (GelH1) aqueous solution (5.0% by mass) 100 g
150g of pure water
Surfactant aqueous solution (CA-3475V, quaternary ammonium salt cationic surfactant, 5.0% by mass, manufactured by Nikko Chemicals) 0.45 g
GelL1 is a low molecular weight gelatin having a weight average molecular weight of 20,000 hydrolyzed by alkali treatment, and GelH1 is an acid-treated gelatin (high molecular weight gelatin) having a weight average molecular weight of 130,000.

(Formation of high refractive index layer 1)
On the low refractive index layer 1 formed on a polyethylene terephthalate film (Toyobo A4300: double-sided easy-adhesion layer) having a thickness of 50 μm heated to 45 ° C. while keeping the coating solution 1 for the high refractive index layer at 45 ° C. The wire bar was applied so that the dry film thickness was 130 nm. Immediately after that, cold air was blown for 1 minute under the condition that the film surface was 15 ° C. or less, and then the hot refractive air of 80 ° C. was blown and dried to form the high refractive index layer 1.

(Formation of laminate)
On the formed high refractive index layer 1, units composed of low refractive index layer 1 / high refractive index layer 1 are alternately laminated in a similar manner, and a total of 10 units (20 layers) are laminated. The near-infrared reflective film 1 consisting of 21 layers was produced by forming the low refractive index layer 1 as follows.

[Preparation of near-infrared reflective films 2 to 4]
In the production of the near-infrared reflective film 1, the homopolymer of the structural unit I-4 of the coating solution 1 for the low refractive index layer is replaced with the homopolymer of the structural unit I-1, the homopolymer of the structural unit I-7, and the structural unit I. Except having changed into the homopolymer of -16, it carried out similarly and produced the near-infrared reflective films 2-4, respectively.

[Preparation of near-infrared reflective film 5]
In the production of the near-infrared reflective film 1, the homopolymer of the structural unit I-4 in the coating solution 1 for the low refractive index layer was changed to a copolymer of the structural unit I-1 and styrene = 1: 1 (molar ratio). In the same manner, a near-infrared reflective film 5 was produced.

[Preparation of near-infrared reflective film 6]
In the production of the near-infrared reflective film 1, the homopolymer of the structural unit I-4 of the coating solution 1 for the low refractive index layer is changed to 30 g, and the high molecular weight gelatin (GelH1) of the coating solution 1 for the high refractive index layer is changed to 70 g. A near-infrared reflective film 6 was produced in the same manner except that.

[Preparation of near-infrared reflective film 7]
In the production of the near-infrared reflective film 6, a near-infrared reflective film 7 was produced in the same manner except that the low molecular weight gelatin (GelL1) of the coating solution 1 for the high refractive index layer was removed.

[Preparation of near-infrared reflective film 8]
In the production of the near-infrared reflective film 6, a near-infrared reflective film 8 was produced in the same manner except that the surfactant of the coating liquid 1 for the high refractive index layer was removed.

[Preparation of near-infrared reflective film 9]
(Formation of laminate)
Using a slide hopper coating apparatus capable of coating 21 layers simultaneously, using the coating solution 1 for the low refractive index layer and the coating solution 1 for the high refractive index layer prepared in the production of the near-infrared reflective film 1, the side closer to the substrate The low refractive index layer 1 (aiming at 175 nm) and the high refractive index layer 1 (aiming at 135 nm) are alternately formed thereon, and the low refractive index layer 1 is formed as the uppermost layer. The refractive index layer is composed of 10 layers, a total of 21 layers, on a polyethylene terephthalate film (Toyobo A4300: double-sided easy-adhesion layer) having a thickness of 50 μm heated to 45 ° C. while being kept at 45 ° C. Simultaneous multilayer coating was performed. Immediately after that, cold air was blown for 1 minute under the condition that the film surface was 15 ° C. or less, and then the hot air of 80 ° C. was blown and dried to produce a near-infrared reflective film 5. In addition, when the cross section of the coating film was observed by TEM, when the mixed film thickness of the low refractive index layer and the high refractive index layer was confirmed by EDX analysis, it was 50 nm or less.

[Preparation of near-infrared reflective film 10]
In the production of the near-infrared reflective film 1, the high molecular weight gelatin (GelH1) aqueous solution (5.0% by mass) of the coating solution 1 for the high refractive index layer was changed to 70 g, and the homopolymer aqueous solution of structural unit I-4 (5 A near-infrared reflective film 10 was prepared in the same manner except that 30 g (mass%) was added.

[Preparation of near-infrared reflective film 11]
In producing the near-infrared reflective film 1, a near-infrared reflective film 11 was produced in the same manner except that the homopolymer of the structural unit I-4 of the coating solution 1 for the low refractive index layer was removed.

[Preparation of near-infrared reflective film 12]
In producing the near-infrared reflective film 6, a near-infrared reflective film 12 was produced in the same manner except that the homopolymer of the structural unit I-4 of the coating liquid 1 for the low refractive index layer was removed.

[Preparation of near-infrared reflective film 13]
In the production of the near-infrared reflective film 9, a near-infrared reflective film 13 was produced in the same manner except that the homopolymer of the structural unit I-4 of the coating liquid 1 for the low refractive index layer was removed. In addition, when the cross section of the coating film was observed by TEM, the mixed film thickness of the low refractive index layer and the high refractive index layer was confirmed by EDX analysis, and was 100 nm.

  The difference in refractive index between the low refractive index layer and the high refractive index layer constituting the near-infrared reflective films 1 to 13 was 0.1 or more.

<< Evaluation of near-infrared reflective film >>
About each produced said near-infrared reflective film, the following characteristic value measurement and performance evaluation were performed.

(Thickness uniformity)
Several portions of the sample were taken, the film thickness was measured with a cross-sectional TEM, and evaluated according to the following criteria.

A: Variation in film thickness is less than 3% O: Variation in film thickness is 3% or more and less than 5% Δ: Variation in film thickness is 5% or more and less than 10% (no problem in practice)
X: Variation in film thickness is 10% or more <Haze>
The haze was measured with a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) and evaluated according to the following criteria.

○: Haze is 1% or less △: Haze exceeds 1% to 3% or less ×: Haze exceeds 3% (near infrared transmittance and visible light transmittance)
Using a spectrophotometer (using an integrating sphere, manufactured by Hitachi, Ltd., U-4000 type), the transmittance in the region of 300 to 2000 nm was measured. The near-infrared transmittance was the transmittance at 1200 nm, and the visible light transmittance was the transmittance at 550 nm.

  The evaluation results are shown in Table 1.

  As is clear from the results shown in Table 1, the near-infrared reflective film of the present invention has high near-infrared reflectance and visible light transmittance, and is excellent in film thickness uniformity and haze.

Example 2
[Production of near-infrared reflector]
Near-infrared reflectors 1 to 10 were produced using the near-infrared reflective films 1 to 10 produced in Example 1. Near-infrared reflectors 1 to 10 were prepared by adhering the near-infrared reflective films of Samples 1 to 10 with an acrylic adhesive on a transparent acrylic resin plate having a thickness of 5 mm and 20 cm × 20 cm, respectively.

[Evaluation]
About the produced near-infrared reflectors 1-10, the reflectance in the 800-1400 nm area | region of each near-infrared reflective film is used using a spectrophotometer (integral sphere use, the Hitachi Ltd. make, U-4000 type). The average value was measured, and this was taken as the near infrared reflectance. As a result, the near-infrared reflectors 1 to 10 can be easily used despite the large size of the near-infrared reflector, and by using the near-infrared reflective film of the present invention, Excellent near infrared reflectivity could be confirmed.

Claims (5)

Near-red having at least one unit composed of a high refractive index layer and a low refractive index layer on a substrate, and having a refractive index difference of 0.1 or more between the high refractive index layer and the low refractive index layer In the external reflection film, at least one of the high refractive index layer and the low refractive index layer contains a metal oxide particle whose surface is coated with low molecular gelatin , and a water solution containing a structural unit represented by the following general formula (I) A near-infrared reflective film comprising a functional polymer A.
(In the formula, R represents a hydrogen atom or a methyl group, Q represents —C (═O) O—, or —C (═O) NRa—, Ra represents a hydrogen atom or an alkyl group, and A represents a substituted group). or unsubstituted alkylene group or, _- (CH 2 _CHRbO) .Rb representing the x-CH 2 CHRb- represents a hydrogen atom or an alkyl group, x represents the average number of repeating units). The near-infrared reflective film according to claim 1 , further comprising a water-soluble polymer B selected from a polymer having a reactive functional group, an inorganic polymer, a thickening polysaccharide, and gelatin. Further, near infrared reflection film according to claim 1 or 2, characterized in that it contains a cationic surfactant. It is a manufacturing method of the near-infrared reflective film of any one of Claims 1-3 , Comprising: At least 2 layer is coated simultaneously, The manufacturing method of the near-infrared reflective film characterized by the above-mentioned. The near-infrared reflection obtained by the manufacturing method of the near-infrared reflective film of any one of Claims 1-3 on the at least one surface side of a base | substrate, or the near-infrared reflective film of Claim 4. A near infrared reflector comprising a film.