JP2012155052A - Near-infrared reflection film, production method of the same and near-infrared reflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a near-infrared reflection film with a low production cost, having a large area and flexibility, high reflecting property for near-infrared rays and high transmittance for visible rays, and improved in optical uniformity of a coating film by multi-layer coating using a water-based coating liquid for forming a refractive index layer.SOLUTION: The near-infrared reflection film includes at least one unit consisting of a high refractive index layer and a low refractive index layer on a substrate, in which the difference in the refractive index between the high refractive index layer and the low refractive index layer adjacent to each other is 0.1 or more and 1.40 or less. At least one of the high refractive index layer and the low refractive index layer contains a water-soluble polymer, metal oxide particles and a compound expressed by a general formula (1).

Description

  The present invention relates to a near-infrared reflective film excellent in near-infrared reflectivity, visible light transparency, and film flexibility, a manufacturing method thereof, and a near-infrared reflector provided with the near-infrared reflective film.

  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 laminated film comprising a structure in which a high refractive index layer and a low refractive index layer are alternately laminated is formed by a dry film forming method such as a vapor deposition method or a sputtering method. 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 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.

  However, in the methods disclosed in Patent Document 1 and Patent Document 2, since the medium of the coating liquid for forming the high refractive index layer is mainly formed of an organic solvent, the formation of the high refractive index layer and the drying are performed. Occasionally, a large amount of organic solvent is scattered, which causes environmental problems. Furthermore, in the method disclosed above, an ultraviolet curable binder or a thermosetting binder is used as a binder, and a high refractive index layer is formed and then cured by ultraviolet rays or heat. It has become.

  Multi-layer coating using a water-based refractive index forming coating solution, not an organic solvent, reduces manufacturing costs, enables a large area, is flexible, has excellent near-infrared reflectivity, and transmits visible light Although a near-infrared reflective film having a high rate and a near-infrared reflector provided with the near-infrared reflective film are also conceivable, it is difficult to achieve both increase in the viscosity of the coating liquid and prevention of particle aggregation, and it has not been put into practical use.

  As a means for increasing viscosity, an example in which a compound having a pyridyl group and an amide group is used as a gelling agent for an electrolytic solution is known (for example, see Patent Documents 3 and 4). Patent Document 3 discloses an antibacterial composition containing the compound. Patent Document 4 discloses an example in which the compound is used as a gel electrolyte of a dye-sensitized solar cell, but does not disclose any configuration or effect of the present invention.

JP-A-8-110401 JP 2004-123766 A JP 2010-143869 A JP 2007-115605 A

  The present invention has been made in view of the above problems, and its purpose is low manufacturing cost, large area, flexibility, near infrared reflectivity, and high visible light transmittance. And it is providing the near-infrared reflector which provided the near-infrared reflective film and the near-infrared reflective film with which the optical uniformity of the coating film improved.

  The above object of the present invention can be achieved by the following configuration.

  1. The substrate has at least one unit composed of a high refractive index layer and a low refractive index layer, and the refractive index difference between the adjacent high refractive index layer and the low refractive index layer is 0. In the near-infrared reflective film that is 10 or more and 1.40 or less, at least one of the high refractive index layer and the low refractive index layer includes a water-soluble polymer, metal oxide particles, and the following general formula ( 1. A near-infrared reflective film comprising the compound represented by 1).

(In the formula, X represents a halogen atom, PF ₆ , BF ₄ , or CF ₃ SO ₃ , and n represents an integer of 2 or more and 30 or less.)
2. 2. The near-infrared reflective film as described in 1 above, wherein the high refractive index layer contains, as the metal oxide particles, rutile-type titanium oxide particles having a volume average particle size of 5 or more and 100 nm or less.

  3. 3. The near-infrared reflective film as described in 1 or 2 above, wherein the water-soluble polymer is gelatin.

  4). 4. The near-infrared reflective film according to any one of 1 to 3, wherein at least one of the high refractive index layer and the low refractive index layer is a water-soluble polymer, metal oxide particles, and the general formula (1) A method for producing a near-infrared reflective film, comprising using a coating solution containing a compound represented by formula (1):

  5). 4. A near-infrared reflector having the near-infrared reflective film according to any one of 1 to 3 on at least one surface side of a substrate.

  According to the present invention, the manufacturing cost is low, the area can be increased, the flexibility is excellent, the near infrared reflectivity is high, the visible light transmittance is high, and the optical uniformity of the coating film is improved. A near-infrared reflective film and a near-infrared reflector provided with the near-infrared reflective film could be provided.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  The present invention comprises at least one of a high refractive index layer and a low refractive index layer of a near-infrared reflective film, a water-soluble polymer, metal oxide particles, and a compound represented by the general formula (1). A near-infrared reflective film having the above-described effects could be obtained by forming using the aqueous refractive index forming coating solution.

The effects of the compound of the general formula (1) of the present invention are estimated as follows. Since the compound of the general formula (1) has an amide group and a cationic pyridinium group in the unit structure, i) the viscosity of the coating solution increases due to the formation of hydrogen bonds between the amide groups, and the film thickness at the time of coating Stability is improved.

  ii) Further, in the present invention, a metal oxide is used. Usually, metal oxides are used dispersed in a coating solution. However, when a polymer compound is dissolved in this dispersion, the dispersion of the metal oxide is destroyed and aggregation precipitates, resulting in a highly transparent coating film. I can't. The compound of the general formula (1) has a pyridinium group, which acts as a dispersion protective agent on the surface of the metal oxide and contributes to the dispersion stability of the metal oxide.

  From i) and ii), it is presumed that the film thickness stability during coating and the dispersion stability of the group oxide are compatible. Further, in the present invention, it was possible to more stably apply the aqueous refractive index forming coating liquid of the high refractive index layer and the low refractive index layer by simultaneously applying the multilayer.

  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》
In the near-infrared reflective film of the present invention, on a substrate, at least one unit composed of a high refractive index layer and a low refractive index layer is laminated, and the adjacent high refractive index layer and low refractive index layer are One of the characteristics is that the difference in refractive index is 0.10 or more. Furthermore, as the optical characteristics of the near-infrared reflective film of the present invention, the transmittance in the visible light region shown in JIS R3106-1998 is 50% or more, and the reflectance is 50% in the wavelength region of 900 nm to 1400 nm. It is preferable to have a region that exceeds.

  In general, in the near-infrared reflective 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, in at least one unit composed of a high refractive index layer and a low refractive index layer, the refractive index difference between the adjacent high refractive index layer and low refractive index layer is 0.10 to 1.40. It is characterized by being, Preferably it is 0.3 or more, More preferably, it is 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 difference in refractive index is smaller than 0.10, it is necessary to laminate 200 layers or more, which not only reduces productivity but also scattering at the lamination 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.

  Next, the basic configuration outline 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, it is sufficient that at least one unit composed of a high refractive index layer and a low refractive index layer is laminated on a substrate, but a preferable high refractive index layer and low As the number of refractive index layers, from the above viewpoint, the range of the total number of layers is 100 layers or less, that is, 50 units or less, more preferably 40 layers (20 units) or less, and even more preferably 20 Layer (10 units) or less.

  In the near-infrared reflective film of the present invention, the difference in refractive index between the adjacent high refractive index layer and low refractive index layer is 0.10 or more. When there are a plurality of refractive index layers as described above, it is preferable that all refractive index layers satisfy the requirements defined in the present invention. However, the outermost layer and the lowermost layer may be configured outside the requirements defined in the present invention.

  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.

(Compound represented by the general formula (1))
In the present invention, the compound represented by the general formula (1) is simultaneously contained in the water-soluble polymer and the metal oxide particles. The compound represented by the general formula (1) may be contained as one kind of compound, or may be contained as a mixture of at least two kinds. In the present invention, it is desirable that at least two compounds corresponding to the general formula (1) are contained.

  The compound represented by the general formula (1) can be synthesized by a known synthesis method, for example, by the method described in JP 2010-143869 A.

  In the general formula (1), n represents 2 to 30. When n is less than 2, the thickening effect is hardly exhibited. On the other hand, when 31 or more, the dispersion stability of the metal oxide is lowered. A preferable number of n is 3 or more and 10 or less. A preferred counter ion is a chloro ion.

  The preferable addition amount of all the compounds represented by the general formula (1) is 0.001% by mass to 2% by mass, and more preferably 0.01% by mass to 0.5% by mass with respect to 1 l of the coating solution.

  The addition layer of the compound represented by the general formula (1) is a feature of the present invention that it is the same layer as the metal oxide particles, but may be included in a layer not containing the metal oxide particles.

(Metal oxide particles)
As the metal oxide particles used in the high refractive index layer according to the present invention, it is preferable to use metal oxide particles having a refractive index of 2.0 or more and a volume average particle size of 100 nm or less, such as zirconium oxide, Although cerium oxide, titanium oxide, etc. can be mentioned, it is particularly preferable to use rutile type titanium oxide particles.

<Rutyl type 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. .

  In the present invention, the metal oxide particles are preferably rutile (tetragonal) titanium oxide particles having a volume average particle diameter of 100 nm or less.

  The volume average particle size here is a volume average particle size of primary particles or secondary particles dispersed in a medium, and can be measured by a laser diffraction / scattering method, a dynamic light scattering method, or the like.

  The volume average particle diameter of the rutile-type titanium oxide particles according to the present invention is preferably 100 nm or less, more preferably 4 nm or more and 50 nm or less, and further preferably 4 nm or more and 30 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. Titanium oxide particles having a volume average particle size exceeding 100 nm are not limited to those used in the high refractive index layer, not limited to the present invention.

The volume average particle diameter of the rutile-type titanium oxide particles according to the present invention means that the particles themselves or particles appearing on the cross section or surface of the refractive index layer are observed with an electron microscope, and the particle diameter of 1,000 arbitrary particles is determined. measured, the _{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 respectively In the group, when the surface area per particle is a _i and the volume is v _i , the volume average particle size m _v = {Σ (v _i · d _i )} / {Σ (v _i )} The average particle size weighted by the volume.

  Furthermore, the titanium oxide particles according to the present invention are preferably monodispersed. The monodispersion here means that the monodispersity obtained by the following formula is 40% or less. The particles are more preferably 30% or less, and particularly preferably 0.1 to 20%.

Monodispersity = (standard deviation of particle size) / (average value of particle size) × 100
<Method for producing rutile type titanium oxide sol>
In the present invention, 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 titanium. It is preferable to use an aqueous titanium oxide sol in which the zeta potential of the particles 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. In the present invention, it is preferable to use an aqueous sol of titanium oxide which has a pH of 1.0 to 3.0 and has a positive zeta potential and is not subjected to such surface treatment.

  Examples of a method for preparing a rutile type titanium oxide sol that can be used in the present invention include, for example, JP-A-63-17221, JP-A-7-819, JP-A-9-165218, and JP-A-11-43327. Reference can be made to the matters described in Japanese Patent Laid-Open Nos. 63-17221, 7-819, 9-165218, 11-43327, and the like.

  In addition, as for other methods for producing the rutile type titanium oxide according to the present invention, for example, “Titanium oxide-physical properties and applied technology”, Manabu Seino p255-258 (2000), Gihodo Publishing Co., Ltd. The method of the step (2) described in the paragraph numbers 0011 to 0023 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.

  In the near-infrared reflective film of the present invention, it is preferable to add rutile type titanium oxide having a volume average particle size of 100 nm or less as a metal oxide to the high refractive index layer, and the metal oxide and the high refractive index layer. It is more preferable to add to both layers of the low refractive index layer. In the present invention, the content of the metal oxide in the high refractive index layer is preferably 15% by mass or more and 50% by mass or less, more preferably 20% by mass or more, based on the total mass of the high refractive index layer. It is 40 mass% or less.

(Water-soluble polymer)
Examples of the water-soluble polymer according to the present invention include gelatin, collagen peptides, celluloses, thickening polysaccharides, and polymers having reactive functional groups. Preferred are gelatin and collagen peptides. Hereinafter, these water-soluble polymers will be described.

  The water-soluble polymer of the present invention is a temperature at which the water-soluble polymer is most dissolved, and is filtered through a G2 glass filter (maximum pores 40 to 50 μm) when dissolved in water at a concentration of 0.5% by mass. In this case, the mass of the insoluble matter filtered out is within 50% by mass of the added water-soluble polymer.

(gelatin)
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).

<Low molecular weight gelatin>
When the gelatin of the present invention is used together with metal oxide particles, low molecular weight gelatin is applied from the viewpoint of preventing uneven coating due to dispersion failure in the coating solution of the metal oxide and clouding of the coating film after formation. And application to the same layer as the layer containing metal oxide particles is more preferable.

  The low molecular weight gelatin or collagen peptide according to the present invention is one having a weight average molecular weight of 30,000 or less, and further, the content of a high molecular gelatin component having a weight molecular weight of 100,000 or more is 1.0% by mass or less. It is preferable.

  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 and collagen peptide used in the present invention preferably have a weight average molecular weight of 2,000 to 30,000, particularly preferably 5,000 to 25,000.

  When the weight average molecular weight exceeds 30,000, a high-viscosity region and a low-viscosity region are partially formed in the coating solution, which makes it difficult to handle the solution. If the weight average molecular weight is less than 2000, a large amount of low molecular weight gelatin is required, the volume ratio of the metal oxide fine particles is reduced, the refractive index difference is reduced, and the number of necessary layers is increased.

  In the low molecular weight gelatin and collagen peptide, in the preparation step of the low molecular gelatin and collagen peptide, the high molecular weight gelatin having a weight average molecular weight of 100,000 or more used as a raw material is sufficiently decomposed, and the content is 1.0 mass. It is preferable to appropriately set conditions such as the type and amount of gelatinolytic enzyme and the temperature and time during the enzymatic degradation so that the enzymatic degradation of the polymer gelatin molecule is optimally carried out so as to be not more than%.

<High molecular weight gelatin>
In the present invention, it is desirable that at least the high refractive index layer contains high molecular weight gelatin having a weight average molecular weight of 100,000 or more. The weight average molecular weight of the high molecular weight gelatin is particularly preferably in the range of 100,000 or more and 200,000 or less.

  In the present invention, the weight average molecular weight of the high molecular weight gelatin used 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 Photography Society, 47, 237 (1984), etc., the α component (molecular weight of about 100,000), which is a structural unit of collagen, and its dimer 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 obtained by irregularly cutting these components.

  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.

  The measurement of gelatin molecular weight distribution is described in the above-mentioned documents and JP-A-60-80838, JP-A-62-87952, JP-A-62-265645, JP-A-62-279329, and JP-A-64-46742. The gel permeation chromatographic method is used. In the present invention, the ratio of each molecular weight component of gelatin is determined by the GPC method under the following conditions.

a) Column: Asahipak, GS-620 (Asahi Kasei Kogyo Co., Ltd.)
Two connected in series Column temperature 50 ℃
b) Eluent: Equal volume mixed solution of 0.1 mol / L KH ₂ PO ₄ and 0.1 mol / L Na ₂ HPO ₄ pH 6.8 Flow rate 1.0 ml / min
c) Sample: 0.2% eluent solution of gelatin Injection volume 100 μl
d) Detection: UV absorption spectrophotometer (UV wavelength 230 nm)
Looking at the change in absorption at 230 nm due to the retention time, first the peak at the exclusion limit appears, then the peaks due to the γ component, β component, and α component of gelatin in turn, and as the retention time becomes longer, The shape will gradually decay. The molecular weight can be determined from the retention time of the outflow curve calibrated with a standard sample.

  The α component is composed of a polypeptide chain having a molecular weight of about 100,000. Gelatin such as α chain dimer (β component) and trimer (γ component) is an aggregate of gelatin molecules having various molecular weights. In addition, gelatin having a predetermined average molecular weight can be obtained from a gelatin manufacturer.

  Examples of the method for producing high molecular weight gelatin having a weight average molecular weight of 100,000 or more 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.

  In the present invention, the high refractive index layer and the low refractive index layer according to the present invention are 1) a low molecular weight gelatin or collagen peptide having a weight average molecular weight of 30,000 or less, and 2) a high molecular weight having a weight average molecular weight of 100,000 or more. It is preferable to contain gelatin, but whether the high refractive index layer and the low refractive index layer contain gelatin or collagen peptide having such a molecular weight can be confirmed by the following method.

  After isolating the high refractive index layer and the low refractive index layer constituting the near-infrared reflective film, after measuring the molecular weight distribution of gelatin by the gel permeation chromatography method (GPC method), the horizontal axis indicates the molecular weight of gelatin. After plotting the content on the vertical axis and preparing a molecular weight distribution curve, the molecular weight is determined to be 30,000 or less and the maximum peaks of two contents appearing when the molecular weight is 100,000 or more.

<Hardener for gelatin>
In the high refractive index layer coating solution and the low refractive index layer coating solution according to the present invention, after forming the high refractive index layer or the low refractive index layer, a hardener is added as necessary to harden the gelatin coating film. You can also

  As the hardener that can be used, known compounds used as hardeners for ordinary photographic emulsion layers can be used, such as 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, a water-soluble cellulose derivative can be preferably used. For example, water-soluble cellulose derivatives such as carboxymethyl cellulose (cellulose carboxymethyl ether), methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose. Examples thereof include cellulose derivatives, carboxymethyl cellulose (cellulose carboxymethyl ether) and carboxyethyl cellulose which are carboxylic acid group-containing celluloses.

<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. It is a polysaccharide with a large difference in characteristics, and when adding metal oxide fine particles, it causes a viscosity increase that seems to be due to hydrogen bonding with the metal oxide fine particles at a low temperature. When added, it is a polysaccharide that increases its viscosity at 15 ° C. by 1.0 mPa · s or more, preferably 5.0 mPa · s or more, more preferably 10.0 mPa · s or more. Polysaccharides.

  Examples of the thickening polysaccharide applicable to the present invention include 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), arabinogalactoglycan (eg, soybean-derived glycan, microorganism-derived glycan, etc.), Red algae such as glucuronoglycan (for example, gellan gum), glycosaminoglycan (for example, hyaluronic acid, keratan sulfate, etc.), alginic acid and alginates, agar, κ-carrageenan, λ-carrageenan, ι-carrageenan Derived from Natural polymeric polysaccharides and the like, from the viewpoint of not lowering the dispersion stability of the metal oxide fine particles coexisting in the coating solution, preferably, those whose structural unit has no carboxyl group or sulfonic acid group. Such polysaccharides include, for example, pentoses such as L-arabitose, D-ribose, 2-deoxyribose and D-xylose, and hexoses such as D-glucose, D-fructose, D-mannose and D-galactose only. It is preferable that it is a polysaccharide. Specifically, tamarind seed gum known as xyloglucan whose main chain is glucose and side chain is glucose, guar gum known as galactomannan whose main chain is mannose and side chain is glucose, cationized guar gum, Hydroxypropyl guar gum, locust bean gum, tara gum, and arabinogalactan whose main chain is galactose and whose side chain is arabinose can be preferably used. 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 thickening polysaccharides in combination.

<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, steel Len-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 polymers, vinyl naphthalene-maleic acid copolymers, vinyl acetate-maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers, and the like Salt. Among these, particularly preferable examples include polyvinyl alcohol, polyvinyl pyrrolidones, and copolymers containing the same.

  The weight average molecular weight of the water-soluble polymer is preferably 1,000 or more and 200,000 or less. Furthermore, 3,000 or more and 40,000 or less are more preferable.

  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 degree of saponification is preferably 70 to 100%, particularly preferably 80 to 99.5%.

  Examples of the cation-modified polyvinyl alcohol have 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 and an epoxy curing agent are preferable.

(High refractive index layer)
The high refractive index layer according to the present invention preferably contains 1) a low molecular weight gelatin or collagen peptide having a weight average molecular weight of 30,000 or less, and 2) a high molecular weight gelatin having a weight average molecular weight of 100,000 or more. . In the present invention, the content of low molecular weight gelatin or collagen peptide in the high refractive index layer is preferably 10% by mass or more and 50% by mass or less, more preferably 15% by mass of the total mass of the high refractive index layer. % Or more and 30% by mass or less. The content of high molecular weight gelatin in the high refractive index layer is preferably 10% by mass or more and 50% by mass or less, more preferably 20% by mass or more and 40% by mass, based on the total mass of the high refractive index layer. % Or less.

  In the present invention, each water-soluble polymer other than the gelatin or collagen peptide is preferably contained in the range of 5.0% by mass to 50% by mass with respect to the total mass of the high refractive index layer. More preferably, it is at least 40% by mass. However, when using together with water-soluble polymer, for example, emulsion resin, it may contain 3.0 mass% or more. When the amount of the water-soluble polymer is small, the film surface is disturbed and the transparency tends to deteriorate during drying after coating the high refractive index layer. 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.

(Low refractive index layer)
In the present invention, the low refractive index layer has a refractive index lower than that of the above-described high refractive index layer by at least 0.10. The low refractive index layer preferably has a refractive index of 1.6 or less. Furthermore, it is 1.30-1.50.

  In the low refractive index layer according to the present invention, a material in which metal oxide particles are dispersed in a water-soluble polymer is used. The water-soluble polymer compound used in the low refractive index layer is the same as the water-soluble polymer described in the high refractive index layer, that is, polymers having celluloses, thickening polysaccharides and reactive functional groups. And various gelatins can be used. The water-soluble polymer used in the high-refractive index layer and the low-refractive index layer may be the same or different, but the same is preferable in carrying out simultaneous multilayer coating.

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

  In the present invention, silicon dioxide preferably has 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 average particle diameter of the metal oxide according to the present invention is such that the particle itself or particles appearing on the cross section or surface of the refractive index layer are observed with an electron microscope, and the particle diameter of 1,000 arbitrary particles is measured. 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.

  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 surface opposite to the measurement surface (back surface) of each sample is roughened, and then light absorption is performed with a black spray. Then, the reflection of light on the back surface is prevented, and the reflectance in the visible light region (400 nm to 700 nm) is measured at 25 points under the condition of regular reflection at 5 degrees to obtain an average value. Ask.

[Other additives]
Various additives can be used in the high refractive index layer and the low refractive index layer according to the present invention as necessary.

<Amino acids with an isoelectric point of 6.5 or less>
The amino acid referred to in the present invention is 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-, and γ-, but has an isoelectric point of 6.5 or less. It is an amino acid. 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.

  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).

  Specific examples of preferable amino acids include aspartic acid, glutamic acid, glycine, serine, and the like, and glycine and serine are particularly preferable.

  The isoelectric point of an amino acid means this pH value because an amino acid balances positive and negative charges in a molecule at a specific pH, and the overall charge becomes zero. In the present invention, amino acids having an isoelectric point of 6.5 or less are used. The isoelectric point of each amino acid can be determined by isoelectric focusing at a low ionic strength.

<Emulsion resin>
In the present invention, it is preferable that the high refractive index layer or the low refractive index layer according to the present invention further contains an emulsion resin.

  The emulsion resin referred to in the present invention is resin fine particles obtained by emulsion-polymerizing an oil-soluble monomer in an aqueous solution containing a dispersant and using an initiator.

  In general, as a dispersant used in the polymerization of an emulsion, in addition to a low molecular weight dispersant such as an alkyl sulfonate, an alkyl benzene sulfonate, diethylamine, ethylenediamine, and a quaternary ammonium salt, polyoxyethylene is used. Examples thereof include polymer dispersants such as nonylphenyl ether, polyethylene ethylene laurate ether, hydroxyethyl cellulose, and polyvinylpyrrolidone.

  The emulsion resin according to the present invention is 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, an oil-soluble monomer, It is 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 are different from emulsion resins 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 for each refractive index layer>
Various 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, JP-A-3-13376, etc., various surfactants of anion, cation or nonion, JP-A-59- 42993, 59-52689, 62-280069, 61-242871, and JP-A-4-219266, etc., whitening agents such as sulfuric acid, phosphoric acid, acetic acid, PH adjusters such as citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, antifoaming agents, lubricants such as diethylene glycol, preservatives, Antistatic agents, can also contain various known additives such as a matting agent.

〔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 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. 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.

[Method for producing near-infrared reflective film]
In the method for producing a near-infrared reflective film of the present invention, at least one unit composed of a high refractive index layer and a low refractive index layer is formed on a substrate, and the adjacent high refractive index layer and the adjacent The refractive index difference from the low refractive index layer is 0.10 or more, and the high refractive index layer is 1) a low molecular weight gelatin or collagen peptide having a weight average molecular weight of 30,000 or less, and 2) a weight average molecular weight of 100,000. It is characterized in that it is formed using a coating solution for forming a high refractive index layer containing the above high molecular weight gelatin and 3) metal oxide particles. 3) Preparation method in which the surface of metal oxide particles is coated with 1) low molecular weight gelatin or collagen peptide having a weight average molecular weight of 30,000 or less, and 2) high molecular weight gelatin having a weight average molecular weight of 100,000 or more is added. Preferred to prepare in There.

  In the method for producing a near-infrared reflective film of the present invention, a unit composed of a high refractive index layer and a low refractive index layer is laminated on a base material. Specifically, the high refractive index layer and the low refractive index are formed. It is preferable to form a laminate by alternately applying and drying the rate layer.

  Examples of the coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or US Pat. Nos. 2,761,419 and 2,761,791. A slide bead coating method using an hopper, an extrusion coating method, or the like is preferably used.

  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 30,000 mPa · s, further preferably 3,000 to 30,000 mPa · s, and most preferably 10 , 30,000 to 30,000 mPa · s.

  As a coating and drying method, the 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 once cooled to 1 to 15 ° C. The drying is preferably performed at 10 ° C. or more, and more preferably, the drying conditions are wet bulb temperature 5 to 50 ° C. and film surface temperature 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.

  In the present invention, when preparing the above-mentioned high refractive index layer coating solution, using an aqueous high refractive index layer coating solution prepared by adding and dispersing rutile type titanium oxide having a volume average particle size of 100 nm or less, It is preferable to form a high refractive index layer. At this time, the rutile type titanium oxide is added to the high refractive index layer coating solution as an aqueous titanium oxide sol having a pH of 1.0 or more and 3.0 or less and a positive zeta potential of the titanium particles. It is preferable to prepare.

[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 placed 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 regulator etc. suitably in an adhesion layer.

  The heat insulation performance and solar heat shielding performance of near-infrared reflectors are generally measured according to JIS R 3209 (multi-layer glass) and JIS R 3106 (test methods for transmittance, reflectance, emissivity, and solar heat gain of plate glass). ), JIS R 3107 (calculation method of thermal resistance of sheet glass and heat transmissivity in architecture).

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

  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 Sample 1]
The following composition was dispersed with a ball mill for 48 hours to prepare a dispersion of rutile-type titanium oxide particles.

Rutile-type titanium oxide particles (average primary particle size 15 nm) 40 parts by mass Surfactant (dioctyl sulfosuccinate) 2 parts by mass Toluene 58 parts by mass Thermosetting silicone resin 60% by volume and titanium oxide dispersion A titanium oxide-containing high refractive index layer coating solution 1 blended so as to be 40% by volume was obtained. The coating solution was applied onto a polyethylene terephthalate film having a thickness of 50 μm using a wire bar under a condition that the dry film thickness was 135 nm, and then dried by blowing hot air of 80 ° C., and then 90 ° C. X20 minutes was heat-cured to form a titanium oxide-containing high refractive index layer 1.

  The low-refractive index layer coating solution is the same as the high-refractive index layer coating solution 1 except that the rutile-type titanium oxide particles are changed to colloidal silica (average primary particle diameter 15 nm). 1 was produced.

  The obtained silica-containing low refractive index layer coating solution 1 was applied onto a substrate by a wet coating method using a bar coater to the titanium oxide-containing high refractive index layer 1, and the titanium oxide-containing high refractive index layer hereinafter. In the same manner as in No. 1, the silica-containing low refractive index layer 1 was formed by drying and thermosetting.

  On the silica-containing low-refractive index layer 1 formed as described above, five units each composed of a titanium oxide-containing high-refractive index layer 1 / silica-containing low-refractive index layer 1 were laminated in the same manner, and each of the six layers of high-refractive index layers was laminated. Sample 1 which is a near-infrared reflective film composed of a refractive index layer and a low refractive index layer (12 layers in total) was produced.

[Preparation of Sample 2]
The following composition was dispersed with a ball mill for 4 hours to prepare a dispersion of titanium oxide having a dispersed particle diameter of D50 and 20 nm.

Isopropanol 100 parts by weight Pyridine 3 parts by weight Ethyl silicate (manufactured by Colcoat, active ingredient 30% by weight) 5 parts by weight Rutile-type titanium oxide particles (average primary particle size 15 nm) 10 parts by weight An ultraviolet curable binder (Shin-Etsu) was added to the obtained dispersion. X-12-2400 manufactured by Kagaku Kogyo Co., Ltd. 1.5 parts by mass of active ingredient 30% by mass) 0.15 parts by mass of catalyst (DX-2400 manufactured by Shin-Etsu Chemical Co., Ltd.) is blended and dispersed for 1 hour in a ball mill. Gave a titanium oxide-containing high refractive index layer coating solution 2 having a D50 of 16 nm. The coating solution is applied on a polyethylene terephthalate film having a thickness of 50 μm using a wire bar under the condition that the dry film thickness is 135 nm, dried at 100 ° C., irradiated with ultraviolet rays, cured, and contains titanium oxide. A refractive index layer 2 was formed.

  The low-refractive-index layer coating solution is the same as the high-refractive-index layer coating solution 2 except that the rutile-type titanium oxide particles are changed to colloidal silica (average primary particle diameter 15 nm). 2 was produced.

  The obtained silica-containing low refractive index layer coating solution 2 was applied onto a substrate by a wet coating method using a bar coater on the titanium oxide-containing high refractive index layer. In the same manner as above, the silica-containing low refractive index layer 2 was formed by drying and thermosetting.

  Hereinafter, sample 2 having six units composed of titanium oxide-containing high refractive index layer 2 / silica-containing low refractive index layer 2 was prepared in the same manner as sample 1 which is a near-infrared reflective film.

[Preparation of Sample 3]
(Preparation of high refractive index layer coating solution 1)
The following additives 1) to 5) were added and mixed in this order to prepare a high refractive index layer coating solution 1.

  First, after heating the titanium oxide particle sol to 50 ° C. while stirring, 2) low molecular gelatin was added and stirred for 30 minutes to coat the titanium oxide particle surface with the low molecular gelatin. Subsequently, 3) high molecular gelatin and 4) pure water were added and stirred for 90 minutes, and then 5) a surfactant was added to prepare a high refractive index layer coating solution 1. This preparation method is referred to as preparation pattern A.

1) 20% by mass of titanium oxide particle sol (volume average particle size 35 nm, rutile titanium oxide particles) 60 g
2) 125% 5.0% by weight low molecular weight gelatin (Gel _L1 ) aqueous solution
3) 5.0 mass% high molecular weight gelatin (Gel _H1 ) aqueous solution 100 g
4) 150g of pure water
5) 5.0% by weight surfactant aqueous solution (Cotamine 24P, quaternary ammonium salt cationic surfactant, manufactured by Kao Corporation) 0.45 g
Gel _L1 is a low molecular weight gelatin having a weight average molecular weight of 20,000 hydrolyzed by alkali treatment, and Gel _H1 is an acid-treated gelatin (high molecular weight gelatin) having a weight average molecular weight of 130,000.

(Preparation of low refractive index layer coating solution 1)
The following additives 1) to 5) were added and mixed in this order to prepare a low refractive index layer coating solution 1.

  First, 1) the temperature was raised to 40 ° C. while stirring the colloidal silica, and 2) low molecular gelatin was added and stirred for 10 minutes. Next, 3) high molecular gelatin and 4) pure water were added and stirred for 10 minutes, and 5) a low refractive index layer coating solution 1 was prepared according to Preparation Pattern A in which a surfactant was added.

1) 20% by mass of colloidal silica 68 g
2) 180 mass% low molecular weight gelatin (Gel _L1 ) aqueous solution 180g
3) 5.0 mass% high molecular weight gelatin (Gel _H1 ) aqueous solution 100 g
4) 240g of pure water
5) 5.0 mass% surfactant aqueous solution (Coatamine 24P, quaternary ammonium salt cationic surfactant, manufactured by Kao Corporation) 0.64 g
Gel _L1 is a low molecular weight gelatin having a weight average molecular weight of 20,000 hydrolyzed by alkali treatment, and Gel _H1 is an acid-treated gelatin (high molecular weight gelatin) having a weight average molecular weight of 130,000.

<Preparation of near-infrared reflective film>
While keeping the above prepared high refractive index layer coating solution 1 and low refractive index layer coating solution 1 at 45 ° C., a dry film thickness of 150 nm and a high refractive index layer coating solution are respectively formed on a polyethylene terephthalate film having a thickness of 50 μm. 1 and low refractive index layer coating solution 1 are alternately applied using a slide hopper, and then set by blowing cold air for 1 minute under the condition that the film surface is 15 ° C. or lower. The sample 3 which is a near-infrared reflective film comprised from 12 layers of high refractive index layers and low refractive index layers (24 layers in total) was produced by blowing air and drying.

[Preparation of Sample 4]
Sample 4 was prepared in the same manner as in the preparation of Sample 3 except that PVA was used instead of the low molecular gelatin except for the high-refractive index layer coating solution 1 and the low-refractive index layer coating solution 1. .

[Preparation of Sample 5]
Sample 5 was prepared in the same manner as in the preparation of Sample 4, except that polysaccharide was used instead of PVA.

[Preparation of Sample 6]
Sample 6 was prepared in the same manner as in the preparation of Sample 3, except that the titanium oxide of the high refractive index layer coating solution 1 was changed to zirconium oxide (primary particle diameter 15 nm).

[Preparation of Sample 7]
In preparation of the sample 3, 4) of the preparation pattern A of the coating solution 1 for the high refractive index layer 4) Instead of pure water, a compound of the general formula (1) (n = 3 to 30, X = Cl) was changed to 2.3. Sample 7 was produced in the same manner except that the aqueous solution containing mass% was changed.

[Preparation of Sample 8]
In preparation of the sample 3, 4) of the preparation pattern A of the low refractive index layer coating solution 1) In place of pure water, a compound of the general formula (1) (n = 3 to 30, X = Cl) was changed to 2.3. Sample 8 was produced in the same manner except that the aqueous solution containing mass% was changed.

[Preparation of Sample 9]
In preparation of the sample 3, 4) pure water of the liquid preparation pattern A of the high refractive index layer coating liquid 1 and 4) pure water of the liquid preparation pattern A of the low refractive index layer coating liquid 1 were used instead of general water. Sample 9 was prepared in the same manner except that the compound of formula (1) (n = 3 to 30, X = Cl) was changed to an aqueous solution containing 2.3% by mass.

[Production of Sample 10]
Sample 10 was prepared in the same manner as in the preparation of Sample 9, except that the titanium oxide of the high refractive index layer coating solution 1 was changed to zirconium oxide (primary particle diameter 15 nm).

[Preparation of Sample 11]
In the preparation of the sample 4, 4) pure water of the preparation liquid pattern A of the high refractive index layer coating liquid 1 and 4) pure water of the preparation liquid pattern A of the low refractive index layer coating liquid 1 were used instead of the general water. Sample 11 was prepared in the same manner except that the compound of formula (1) (n = 3 to 30, X = Cl) was changed to an aqueous solution containing 2.3% by mass.

[Preparation of Sample 12]
In the preparation of the sample 5, 4) pure water of the preparation pattern A of the high refractive index layer coating solution 1 and 4) pure water of the preparation pattern A of the low refractive index layer coating solution 1 were used instead of the general water. Sample 12 was prepared in the same manner except that the compound of formula (1) (n = 3 to 30, X = Cl) was changed to an aqueous solution containing 2.3% by mass.

[Preparation of Sample 13]
In the preparation of the sample 9, the compound of the general formula (1) (n = 3 to 30, X = Cl) was changed to the general formula (1) (n = 3 to 20, X = Cl). Thus, Sample 13 was produced.

[Preparation of Sample 14]
Sample 14 was prepared in the same manner as in the preparation of Sample 13, except that the content of the compound of general formula (1) (n = 3 to 20, X = Cl) was changed to 0.1% by mass.

[Preparation of Sample 15]
Sample 15 was prepared in the same manner as in the preparation of Sample 14, except that the low molecular gelatin and the high molecular gelatin in the low refractive index layer coating solution were changed to PVA.

[Preparation of Sample 16]
In the preparation of the sample 14, the same applies except that the general formula (1) (n = 3 to 20, X = Cl) is changed to the general formula (1) (n = 3 to 20, X = BF ₄ ). Sample 16 was prepared.

[Preparation of Sample 17]
In the preparation of the sample 14, the same applies except that the general formula (1) (n = 3 to 20, X = Cl) is changed to the general formula (1) (n = 3 to 20, X = CF ₃ SO ₃ ). Sample 17 was prepared.

Polysaccharide: locust bean gum PVA: polyvinyl alcohol 235 (manufactured by Kuraray Co., Ltd.)
<< Evaluation of near-infrared reflective film >>
About each produced said near-infrared reflective film, the following characteristic value measurement and performance evaluation were performed.

(Measurement of refractive index of each layer)
Samples each having a single layer of a target layer (high refractive index layer, low refractive index layer) whose refractive index is to be measured are prepared on a base material, and each high refractive index layer and low refractive index layer are formed according to the following method. The refractive index of was determined.

  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. The refractive index was obtained from the measurement result of the reflectance in the visible light region (400 nm to 700 nm) under the condition of regular reflection at 5 degrees.

  In Samples 12 and 13, the aggregation of the titanium oxide particles in the high refractive index layer was severe, and the refractive index could not be measured with a film surface quality that could not withstand the evaluation. displayed.

(Measurement of visible light transmittance and near infrared transmittance)
Using the above spectrophotometer (integral sphere use, manufactured by Hitachi, Ltd., U-4000 type), the transmittance in the region of 300 nm to 2000 nm of each near infrared reflective film was measured. The visible light transmittance was a transmittance value at 550 nm, and the near infrared transmittance was a transmittance value at 1200 nm.

<Evaluation of uniformity of optical characteristics>
Using a spectrophotometer (using an integrating sphere, manufactured by Hitachi, Ltd., U-4000 type), the transmittance and reflectance every 5 nm in the region of 300 nm to 2500 nm of each near infrared reflective film were measured. Next, according to the method described in JIS R3106, calculation processing of the measured value and the solar reflection weight coefficient was performed to determine the solar reflectance and solar transmittance, and further, the solar heat acquisition rate (Tts) was determined.

  The Tts were determined for 20 different parts of one sample, and ΔTts = (Tts maximum value) − (Tts minimum value) was used as an index of optical uniformity of the coating film. The smaller ΔTts, the smaller the change in the heat shielding performance, indicating that it is superior.

(Evaluation of flexibility)
About each produced near-infrared reflective film, based on a bending test method based on JIS K5600-5-1, using a bending tester type 1 (manufactured by Imoto Seisakusho, model IMC-AOF2, mandrel diameter φ20 mm), After performing the bending test 1000 times, the near-infrared reflective film surface was visually observed, and the flexibility was evaluated according to the following criteria.

◎: No folding marks or cracks are observed on the near-infrared reflective film surface. ○: Slight bending marks are observed on the near-infrared reflective film surface. X: Many obvious cracks are generated on the surface of the near-infrared reflective film Table 1 shows the measurement results and evaluation results obtained as described above.

  As is clear from the results shown in Table 1, the near-infrared reflective film of the present invention can reduce the near-infrared transmittance without reducing the visible light transmittance, and is flexible. It can be seen that the coating film is excellent in optical uniformity.

Example 2
[Preparation of near-infrared reflectors 1 to 17]
Near-infrared reflectors 1 to 17 were produced using the near-infrared reflective films of Samples 1 to 17 produced in Example 1. Near-infrared reflectors 1 to 17 were prepared by bonding the near-infrared reflective films of Samples 1 to 17 with an acrylic adhesive on a transparent acrylic resin plate having a thickness of 5 mm and 20 cm × 20 cm, respectively.

[Evaluation]
The near-infrared reflectors 7 to 17 of the present invention produced above can be easily used even though the size of the near-infrared reflector is large, and the near-infrared reflective film of the present invention is used. As a result, excellent near-infrared reflectivity could be confirmed.

Claims (5)

The substrate has at least one unit composed of a high refractive index layer and a low refractive index layer, and the refractive index difference between the adjacent high refractive index layer and the low refractive index layer is 0. In the near-infrared reflective film that is 10 or more and 1.40 or less, at least one of the high refractive index layer and the low refractive index layer includes a water-soluble polymer, metal oxide particles, and the following general formula ( 1. A near-infrared reflective film comprising the compound represented by 1).

(In the formula, X represents a halogen atom, PF ₆ , BF ₄ , or CF ₃ SO ₃ , and n represents an integer of 2 or more and 30 or less.)   The near-infrared reflective film according to claim 1, wherein the high refractive index layer contains, as the metal oxide particles, rutile-type titanium oxide particles having a volume average particle size of 5 or more and 100 nm or less.   The near-infrared reflective film according to claim 1 or 2, wherein the water-soluble polymer is gelatin.   The near-infrared reflective film according to any one of claims 1 to 3, wherein at least one of the high refractive index layer and the low refractive index layer comprises a water-soluble polymer, metal oxide particles, and the above general formula ( A method for producing a near-infrared reflective film, which is formed using a coating solution containing the compound represented by 1).   A near-infrared reflector having the near-infrared reflective film according to any one of claims 1 to 3 on at least one surface side of the substrate.