WO2013058141A1

WO2013058141A1 - Infrared shielding film and infrared shield using same

Info

Publication number: WO2013058141A1
Application number: PCT/JP2012/076136
Authority: WO
Inventors: 友香子高
Original assignee: コニカミノルタホールディングス株式会社
Priority date: 2011-10-20
Filing date: 2012-10-09
Publication date: 2013-04-25
Also published as: JP6064911B2; JPWO2013058141A1

Abstract

[Problem] To provide an infrared shielding film that has excellent visible light transparency and infrared shielding properties, and is less susceptible to curling. [Solution] An infrared shielding film having a substrate and a reflecting layer that reflects at least infrared light, wherein the reflecting layer has a plurality of laminated refractive index layers, at least one of the refractive index layers has a refractive index different from that of an adjacent refractive index layer, the bottom layer adjacent to the substrate among the refractive index layers constituting the reflecting layer includes metal oxide microparticles and an emulsion resin, and the bottom layer has a thickness 1.2 to 8 times the average thickness of the refractive index layers other than the bottom layer.

Description

Infrared shielding film and infrared shielding body using the same

The present invention relates to an infrared shielding film and an infrared shielding body using the same.

In recent years, interest in energy conservation measures has increased, and from the viewpoint of reducing the load on cooling equipment, there has been an increasing demand for infrared shielding 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 an infrared shielding 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. A method of forming the above has been proposed. However, the dry film-forming method has problems such as a large vacuum apparatus used for forming, high manufacturing cost, difficult to enlarge, and limited to heat-resistant material as a base material. Yes.

Therefore, a method of forming an infrared shielding film using a wet film forming method instead of the dry film forming method having the above-described problems has been proposed. 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. A method for forming a transparent laminate by coating (for example, see Patent Document 1), and for forming a high refractive index coating film containing a rutile type titanium oxide, a heterocyclic nitrogen compound, a binder precursor, and an organic solvent. A method for forming a transparent laminate by applying a coating composition on a substrate by a wet coating method using a bar coater (for example, see Patent Document 2) is disclosed.

By the way, the infrared shielding film is applied not only to the window glass of buildings and vehicles but also to various other uses. For example, in a plasma display panel, infrared rays are emitted from a display screen, and an infrared shielding film is applied to shield the infrared rays. Therefore, the infrared shielding film is required to have not only an infrared shielding effect but also performance such as scratch resistance and thinning. For imparting scratch resistance to the infrared shielding film, a method of laminating a hard layer on the surface, a method using an organic silicon compound, a method of increasing the thickness of the layer to be laminated, and the like are known. On the other hand, when reducing the thickness of the infrared shielding film, curling occurs in the infrared shielding film, making it difficult to handle in the manufacturing process and processing step of the infrared shielding film, and cracking occurs in the infrared shielding film. Furthermore, there has been a problem in bonding the infrared shielding film to the substrate. Therefore, as a method for suppressing curling due to the thinning, an antiglare film using a modified acrylate compound (see, for example, Patent Document 3), and a hard coat film using a urethane acrylate compound (for example, Patent Document). 4), and a laminate (for example, see Patent Document 5) using a mixture of acrylate compounds having different properties.

JP-A-8-110401 JP 2004-123766 A JP 2005-181996 A JP 2005-288787 A US Patent Application Publication No. 2005/0147768

According to the inventions described in Patent Documents 3 to 5, although curl suppression is recognized, curl suppression means for an infrared shielding film formed by laminating a large number of high refractive index layers and low refractive index layers As it turned out not to be enough.

In addition, a wet film-forming method, particularly a method of sequentially forming a reflective layer that reflects infrared light by applying and drying a coating liquid (hereinafter also referred to as “coating method”) is a method for producing an infrared shielding film. As a useful method, streaks and unevenness may occur in the reflective layer formed using the coating method. However, when compared with the dry film forming method, from the viewpoint of production cost and productivity, the usefulness of the coating method is great, and there is a demand for an infrared shielding film having a configuration to which the coating method can be suitably applied. there were.

Therefore, an object of the present invention is to provide an infrared shielding film that is curled and has excellent visible light transmittance and infrared shielding properties.

In addition, the present invention provides an infrared shielding film in which generation of streaks and / or unevenness in the reflective layer is prevented or suppressed, that is, excellent in coatability even when the reflective layer is formed by a coating method. Objective.

As a result of diligent research, the inventor of the present invention includes the emulsion resin in the refractive index layer (lowermost layer) in contact with the base material to give flexibility to the above and by setting the lowermost layer thick, The present inventors have found that the problem can be solved and have completed the present invention. Further, according to a preferred embodiment, it has been found that by using at least two types of water-soluble resins in combination with the layer in contact with the lowermost layer, the metal oxide fine particles are stabilized and no aggregation occurs, and cracks and haze are improved. It was.

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

1. An infrared shielding film having a base material and a reflective layer that reflects at least infrared light, wherein the reflective layer includes a plurality of laminated refractive index layers, and at least one of the refractive index layers Has a refractive index different from that of an adjacent refractive index layer, and among the refractive index layers constituting the reflective layer, the lowermost layer in contact with the substrate contains metal oxide fine particles and an emulsion resin, and the lowest layer An infrared shielding film having a thickness of 1.2 to 8 times the average thickness of each layer of the refractive index layer other than the lowermost layer;
2. The refractive index layer in contact with the lowermost layer contains at least two types of water-soluble resins. An infrared shielding film according to claim 1;
3. 1. The refractive index layer in contact with the lowermost layer includes a water-soluble resin having an average polymerization degree of 500 or less and a water-soluble resin having an average polymerization degree of 2000 or more. An infrared shielding film according to claim 1;
4). 2. The water-soluble resin having an average polymerization degree of 2000 or more is unmodified polyvinyl alcohol. An infrared shielding film according to claim 1;
5. 2. The water-soluble resin having an average polymerization degree of 500 or less is modified polyvinyl alcohol. Or 4. An infrared shielding film according to claim 1;
6). The lowermost layer further includes a water-soluble resin having a mass 1 to 10 times that of the emulsion resin. ~ 5. An infrared shielding film according to any one of
7). Including the step of forming the emulsion resin using an emulsion having an average particle size of 50 nm or less. ~ 6. The manufacturing method of the infrared shielding film as described in any one of these;
8.1. ~ 6. An infrared shielding body comprising the infrared shielding film according to claim 1 or the infrared shielding film obtained by the production method according to claim 7 on at least one surface of a substrate.

According to the present invention, it is possible to provide an infrared shielding film that suppresses curling and is excellent in visible light transmittance and infrared shielding properties, and an infrared shielding body using the same.

In addition, the present invention can provide an infrared shielding film excellent in applicability in which generation of streaks and / or unevenness in the reflective layer is prevented or suppressed even when the reflective layer is formed by coating. .

Hereinafter, embodiments for carrying out the present invention will be described in detail.

According to one embodiment of the present invention, an infrared shielding film having a base material and a reflective layer that reflects at least infrared light is provided. In this case, the reflective layer has a plurality of stacked refractive index layers, and at least one of the refractive index layers has a refractive index different from that of the adjacent refractive index layer. Of the refractive index layers constituting the reflective layer, the lowermost layer in contact with the base material contains metal oxide fine particles and an emulsion resin, and the lowermost layer is the refractive index layer other than the lowermost layer (hereinafter referred to as the lowermost layer). (Also simply referred to as “other layers”) of 1.2 to 8 times the average thickness of each layer.

In the conventional infrared shielding film, when the manufactured infrared shielding film was dried and the film was cured, the film was curled with the curing. Then, it becomes difficult to bond the film to the substrate due to the occurrence of curling, and since the cured film is hard and brittle, a crack occurs, which is a problem. In particular, when an infrared shielding film was made thin, curling occurred remarkably.

However, according to the present embodiment, the flexibility of the emulsion resin itself is imparted to the lowermost layer by including the emulsion resin in the lowermost layer of the infrared shielding film. Thereby, even if it is a case where it thins, the curl accompanying the hardening at the time of drying an infrared shielding film can be suppressed. Therefore, the infrared shielding film which concerns on this invention can prevent the problem of the bonding to the base | substrate of a film, and generation | occurrence | production of a crack. In addition, by increasing the thickness of the lowermost layer of the infrared shielding film and further containing an emulsion resin in the lowermost layer, there was a concern that degradation of visible light transmission and infrared shielding would be a problem, Surprisingly, it has become clear that the visible light transmittance and the infrared shielding property are not lowered, and the same performance as the conventional infrared shielding film is exhibited.

Hereinafter, the components of the infrared shielding film of the present invention, the form for carrying out the present invention, and the like will be described in detail.

[Infrared shielding film]
The infrared shielding film of this embodiment has a base material and a reflective layer that reflects at least infrared light.

The total thickness of the infrared shielding film is preferably 12 μm to 315 μm, more preferably 15 μm to 200 μm, and still more preferably 20 μm to 100 μm.

[Base material]
The substrate used for the infrared shielding film according to the present invention is preferably a film support. The film support may be transparent or opaque, and various resin films can be used. Specific examples include polyolefin films such as polyethylene and polypropylene; polyester films such as polyethylene terephthalate and polyethylene naphthalate; polyvinyl chloride; and cellulose triacetate. Among these, it is preferable to use a polyester film. The polyester film (hereinafter also simply referred to as “polyester”) is not particularly limited, but is preferably a polyester having a film-forming property having a dicarboxylic acid component and a diol component as main components. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethanedicarboxylic acid, cyclohexanedicarboxylic acid, diphenyl Examples thereof include dicarboxylic acid, diphenylthioether 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 full orange hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are used as the dicarboxylic acid component, and ethylene glycol and 1,4-cyclohexanedimethanol are used as the diol component from the viewpoint of transparency, mechanical strength, dimensional stability, and the like. It is preferable to use polyester as a main constituent. Of 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. It is preferable to use polyester as a constituent component.

The thickness of the substrate according to the present invention is preferably 10 to 300 μm, and more preferably 20 to 150 μm. Two or more substrates may be stacked, and in this case, the types of the substrates may be the same or different.
[Reflective layer]
The reflective layer has a plurality of stacked refractive index layers, and at least one of the refractive index layers has a refractive index different from that of the adjacent refractive index layer. With such a configuration, when infrared light is irradiated from the substrate side or the reflective layer side, at least a part of the infrared light can be reflected to exhibit an infrared shielding effect.

The reflective layer can have various forms. Specifically, in contrast to the adjacent refractive index layer, the refractive index layer having a high refractive index and the refractive index layer having a low refractive index are alternately laminated, as the refractive index layer is laminated, It may include at least one form selected from the group consisting of a form in which the refractive index of the refractive index layer increases and a form in which the refractive index of the refractive index layer decreases as the refractive index layer is laminated. Among these, it is particularly preferable that the reflective layer has only a form in which a refractive index layer having a high refractive index and a refractive index layer having a low refractive index are alternately laminated as compared with the adjacent refractive index layer. In addition, there is no restriction | limiting in particular about the structure of each refractive index layer, as long as it is contained in the technical scope of a claim. Further, all the refractive index layers constituting the reflective layer may be different.

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

The reflectance in a specific wavelength region is determined by the difference in refractive index between two adjacent layers and the number of layers, and the larger the difference in refractive index, the same reflectance can be obtained with a smaller number of layers. The refractive index difference and the required number of layers can be calculated using commercially available optical design software. For example, in order to obtain an infrared reflectance of 90% or more, if the refractive index difference is smaller than 0.1, it is necessary to stack 100 layers or more. In such cases, productivity loss, increased scattering at the stack interface, reduced transparency, and manufacturing failures can occur. From the standpoint of improving reflectivity and reducing the number of layers, there is no upper limit to the difference in refractive index, but practically about 1.4 is the limit.

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

The range of the total number of refractive index layers constituting the reflective layer is preferably 100 layers or less, more preferably 40 layers or less, and even more preferably 20 layers or less.

In the following description, in particular, a refractive index layer having a high refractive index (also referred to as “high refractive index layer”) and a low refractive index layer (also referred to as “low refractive index layer”) as compared with adjacent refractive index layers. One embodiment of the reflective layer in which are alternately stacked will be described. However, the technical scope of the present invention is not limited to this embodiment.

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

Hereinafter, the high refractive index layer and the low refractive index layer constituting the reflective layer of this embodiment will be described.

(High refractive index layer)
The high refractive index layer has a high refractive index as compared with the adjacent refractive index layer. The high refractive index layer of this embodiment usually contains metal oxide fine particles (hereinafter also referred to as “first metal oxide fine particles”) and a water-soluble resin.

The preferable refractive index of the high refractive index layer is 1.80 to 2.50, more preferably 1.90 to 2.20. Further, the thickness per layer of the high refractive index layer is preferably 20 to 800 nm, more preferably 50 to 350 nm.

First metal oxide fine particles The first metal oxide fine particles contained in the high refractive index layer are preferably metal oxide fine particles having a refractive index of 2.0 or more. Specifically, zirconium oxide (ZrO ₂ ), zinc oxide (ZnO), titanium oxide (TiO ₂ ), and the like can be given. Of these, titanium oxide (TiO ₂ ) is preferably used from the viewpoint of the stability of the coating solution for forming the high refractive index layer. Among TiO ₂ , it is particularly preferable to use rutile type titanium oxide having a high refractive index and a low catalytic activity. If the catalytic activity is low, side reactions (photocatalytic reactions) that occur in the high refractive index layer and adjacent layers can be suppressed, and the weather resistance can be increased.

As the titanium oxide particles used in the present invention, the surface of an aqueous titanium oxide sol having a pH of 1.0 to 3.0 and a positive zeta potential of the titanium particles is hydrophobized so that it can be dispersed in an organic solvent. It is preferable to use one.

Examples of a method for preparing an aqueous titanium oxide sol that can be used in the present invention include Japanese Patent Laid-Open Nos. 63-17221, 7-819, 9-165218, and 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, other methods for producing the titanium oxide particles used in the present invention include, for example, a method described in “Titanium oxide—physical properties and applied technology” (Kagino Kiyono p255-258 (2000) Gihodo Publishing Co., Ltd.) Reference can be made to the method of step (2) described in paragraphs “0011” to “0023” of WO2007 / 039953.

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

The first metal oxide particles may be anionized. For example, when titanium oxide is used as the first metal oxide fine particles, the titanium oxide can be anionized by coating the titanium oxide particles with a silicon-containing hydrated oxide. The coating amount of the silicon-containing hydrated compound is 3 to 30% by mass, preferably 3 to 10% by mass, more preferably 3 to 8% by mass. When the coating amount is 30% by mass or less, a desired refractive index of the high refractive index layer can be obtained, and when the coating amount is 3% or more, particles can be stably formed.

The content of the first metal oxide fine particles in the high refractive index layer is preferably 35 to 90% by mass, and more preferably 40 to 80% by mass with respect to the total mass of the high refractive index layer. It is preferable that the content of the first metal oxide fine particles is 35% by mass or more because a difference in refractive index between the high refractive index layer and the low refractive index layer can be increased. Further, it is preferable that the content of the first metal oxide fine particles is 90% by mass or less because flexibility of the film can be obtained and film formation becomes easy.

The average particle diameter of the first metal oxide fine particles is preferably 2 to 100 nm, more preferably 3 to 50 nm, and further preferably 4 to 30 nm. The average particle diameter of the first metal oxide fine particles is the particle itself or the particles appearing on the cross-section and 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 its 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.

Water-soluble resin Although it does not restrict | limit especially as water-soluble resin which can be used for this invention, It is preferable to use the polymer or modified polyvinyl alcohol which has a reactive functional group. These water-soluble resins may be used alone or in combination of two or more. The water-soluble in the water-soluble resin means that 1% by mass or more, more preferably 3% by mass or more is dissolved in 20 ° C. water.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

As the polymerization initiator, those used in this field can be used. For example, inorganic peroxides such as potassium persulfate, ammonium persulfate and hydrogen peroxide, organic peroxides such as peracetic acid, tert-butyl hydroperoxide and di-n-propyl peroxydicarbonate, or 2,2 ′ And azo compounds such as azobis (2-amidinopropane) hydrochloride and 2,2′-azobis (2,4-dimethylvaleronitrile).

The amount of the polymerization initiator used is usually about 0.1 to 5.0 parts by mass and more preferably 0.5 to 3.0 parts by mass with respect to 100 parts by mass of the polymerizable vinyl monomer.

The water-soluble resin is preferably unmodified polyvinyl alcohol or modified polyvinyl alcohol from the viewpoint of transparency. In consideration of the interaction with the water-soluble resin, it is preferable to use a water-soluble resin having a hydroxy group, and it is more preferable to use unmodified polyvinyl alcohol or modified polyvinyl alcohol. In one embodiment, it is possible to use unmodified polyvinyl alcohol (particularly, unmodified polyvinyl alcohol having an average degree of polymerization of 2000 or more) and modified polyvinyl alcohol (particularly, modified polyvinyl alcohol having an average degree of polymerization of 500 or less). This is particularly preferable from the viewpoint of improving the haze. The polyvinyl alcohol preferably has a large number of hydroxy groups, and preferably has a saponification degree of 95% or more. In one embodiment, the water-soluble resin described above may function as a binder or a coating agent for the first metal oxide particles.

The content of the water-soluble resin in the high refractive index layer is preferably 3 to 60% by mass, and more preferably 8 to 35% by mass with respect to the total mass of the high refractive index layer.

Moreover, in the relationship between the water-soluble resin and the first metal oxide fine particles, the mass ratio (F / B) of the mass (F) of the first metal oxide fine particles and the mass (B) of the water-soluble resin is 0.5 to 20 is preferable, and 1.0 to 10 is more preferable.

(Low refractive index layer)
The low refractive index layer has a low refractive index as compared with the adjacent refractive index layer. The low refractive index layer of this embodiment usually contains metal oxide fine particles (hereinafter also referred to as “second metal oxide fine particles”) and a water-soluble resin.

The preferable refractive index of the low refractive index layer is 1.10 to 1.60, more preferably 1.20 to 1.50. The thickness per layer of the low refractive index layer is preferably 20 to 800 nm, and more preferably 50 to 350 nm.

Second metal oxide fine particles By containing the second metal oxide fine particles in the low refractive index layer, the low refractive index layer has a low refractive index.

The second metal oxide fine particles contained in the low refractive index layer are preferably silicon dioxide, and examples thereof include synthetic amorphous silica and colloidal silica. Of these, acidic colloidal silica sol is more preferably used, and colloidal silica sol dispersed in water and / or an organic solvent is more preferably used. The colloidal silica can be obtained by heating and aging a silica sol obtained by metathesis using sodium silicate acid or the like or passing through an ion exchange resin layer. Such colloidal silica is disclosed in, for example, JP-A-57-14091, JP-A-60-219083, JP-A-60-218904, JP-A-61-20792, JP-A-61- No. 188183, No. 63-17807, No. 4-93284, No. 5-278324, No. 6-92011, No. 6-183134, No. 6-297830 No. 7-81214, No. 7-101142, No. 7-179029, No. 7-137431, pamphlet of International Publication No. 94/26530, etc. . Colloidal silica may be a synthetic product or a commercially available product. Further, the colloidal silica may be one whose surface is cation-modified, or may be one treated with Al, Ca, Mg, Ba or the like.

The metal oxide fine particles (preferably silicon dioxide) contained in the low refractive index layer 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 more preferably 20 nm or less, and more preferably 10 nm or less. Moreover, as an average particle diameter of secondary particle | grains, it is preferable from a viewpoint with few hazes and excellent visible light transmittance | permeability that it is 30 nm or less.

The average particle diameter of the second metal oxide fine particles is measured by the same method as that for the first metal oxide fine particles.

The content of the second metal oxide fine particles in the low refractive index layer is preferably 30 to 90% by mass and more preferably 40 to 60% by mass with respect to the total mass of the low refractive index layer. . When the content of the second metal oxide fine particles is 30% or more, a desired refractive index is obtained, and when it is 90% or less, film formation is facilitated.

The second metal oxide fine particles according to the present invention preferably have the same ionicity (charge) as the first metal oxide fine particles. When the second metal oxide fine particles (usually having a negative charge) are used untreated, the first metal oxide fine particles (usually having a positive charge) are anionized as described above. It is preferable. Further, when the first metal oxide fine particles are used untreated, the second metal oxide fine particles are preferably cationized. A repulsive force is generated between the first metal oxide fine particles and the second metal oxide fine particles by the anionization treatment or the cationization treatment. Thereby, agglomeration or the like may be less likely to occur when the low refractive index layer and the high refractive index layer are applied.

A cationic compound is preferably used for the cationization treatment of the second metal oxide fine particles. Examples of the cationic compound include a cationic polymer and a polyvalent metal salt, and a polyvalent metal salt is preferred from the viewpoint of adsorption power and transparency. Examples of polyvalent metal salts include aluminum, calcium, magnesium, zinc, iron, strontium, barium, nickel, copper, scandium, gallium, indium, titanium, zirconium, tin, lead, and other metal hydrochlorides, sulfates, nitrates, Examples include acetate, formate, succinate, malonate, chloroacetate and the like. Of these, water-soluble salts composed of aluminum, calcium, magnesium, zinc and zirconium are preferred because their metal ions are colorless. Particularly preferred are water-soluble aluminum compounds and water-soluble zirconium compounds. Specific examples of water-soluble aluminum compounds include polyaluminum chloride (basic aluminum chloride), aluminum sulfate, basic aluminum sulfate, aluminum potassium sulfate (alum), ammonium aluminum sulfate (ammonium alum), sodium aluminum sulfate, aluminum nitrate, phosphoric acid Examples thereof include aluminum, aluminum carbonate, polysulfuric acid aluminum silicate, aluminum acetate, and basic aluminum lactate. Here, the water solubility in the water-soluble polyvalent metal compound means that it dissolves in water at 20 ° C. in an amount of 1% by mass or more, more preferably 3% by mass or more. Among these, basic aluminum chloride, basic aluminum sulfate, basic aluminum lactate, and basic aluminum acetate are more preferable. Further most preferable is basic aluminum chloride having a basicity of 80% or more, which can be expressed by the following molecular formula. [Al ₂ (OH) _n C _16-n ] _m (where 0 <n <6, m ≦ 10) The basicity is represented by n / 6 × 100 (%). Specific examples of the water-soluble zirconium compound are preferably zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate, zirconium oxychloride, zirconyl lactate, and zirconyl citrate. Zirconyl ammonium carbonate and zirconyl acetate are particularly preferred. In particular, zirconium oxychloride and zirconyl acetate are preferable. The amount of the second metal oxide fine particles is preferably 1% by mass to 15% by mass depending on the shape and particle size of the second metal oxide fine particles.

Water-soluble resin Specific examples of the water-soluble resin, preferable average degree of polymerization, and the like are the same as those of the water-soluble resin described in the high refractive index layer, and thus the description thereof is omitted here.

However, when the high refractive index layer and the low refractive index layer are applied in multiple layers, the combination of the water-soluble resin of the high refractive index layer and the water-soluble resin of the low refractive index layer is used from the viewpoint of efficiently forming a laminate. It is important to choose. It is preferable to use the same water-soluble resin.

The content of the water-soluble resin in the low refractive index layer is preferably 3 to 60% by mass and more preferably 10 to 45% by mass with respect to the total mass of the low refractive index layer.

In the relationship between the water-soluble resin and the second metal oxide fine particles, the mass ratio (F / B) of the mass (F) of the second metal oxide fine particles and the mass (B) of the water-soluble resin. Is preferably 0.5 to 20, and more preferably 1.0 to 10.

(Additive)
You may add a well-known additive suitably to the refractive index layer which comprises a reflection layer. Examples of the additive include a curing agent.

Curing agent The curing agent has a function of curing the water-soluble resin contained in the refractive index layer. By curing, water resistance can be imparted to the refractive index layer.

The curing agent applicable to the present invention is not particularly limited as long as it causes a curing reaction with a water-soluble resin. However, when the water-soluble resin is unmodified polyvinyl alcohol or modified polyvinyl alcohol, boric acid and its A salt (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 octaboric acid or salts thereof. preferable. Boric acid and its salt may be used alone or in combination of two or more, and it is particularly preferable to use a mixed aqueous solution of boric acid and borax. Other known compounds can also be used, and are generally compounds having groups capable of reacting with water-soluble resins, or compounds that promote the reaction between different groups of water-soluble resins. The resin is appropriately selected according to the type of the functional resin. Specific examples of the curing agent include, for example, diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4 monobutanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N— Epoxy curing agents such as diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether; aldehyde curing agents such as formaldehyde and glycoxal; 2,4-dichloro Active halogen type curing agents such as -4-hydroxy-1,3,5-S-triazine; 1.3.5 Active vinyl type such as tris-acryloyl-hexahydro-S-triazine and bisvinylsulfonylmethyl ether Compound: Aluminum alum and the like.

When gelatin is used as the water-soluble resin, examples of the curing agent include vinylsulfone compounds, urea-formalin condensates, melanin-formalin condensates, epoxy compounds, aziridine compounds, active olefins, isocyanates. Organic hardeners such as compounds, inorganic polyvalent metal salts such as chromium, aluminum and zirconium may be used.

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

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, and JP-A-57-87989. , JP-A-60-72785, JP-A-61-146591, JP-A-1-95091, JP-A-3-13376, etc. Nonionic surfactants, JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-228771, and JP-A-4-219266 Fluorescent brighteners, sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, etc. Agents, lubricants such as diethylene glycol, preservatives, antifungal agents, antistatic agents, matting agents, heat stabilizers, antioxidants, flame retardants, crystal nucleating agents, inorganic particles, organic particles, thickeners, lubricants, infrared rays Examples include various known additives such as absorbents, dyes, and pigments.

Note that the reflective layer may include a mixed layer including both the low refractive index layer component and the high refractive index layer component. Such a mixed layer is determined to be included in either the high refractive index layer or the low refractive index layer depending on the components constituting the mixed layer (the above-described first and second metal oxide fine particles). That is, when the mass of the first metal oxide fine particles contained in the mixed layer is larger than the mass of the second metal oxide fine particles, it is determined that the mixed layer is contained in the high refractive index layer. On the other hand, when the mass of the second metal oxide fine particles contained in the mixed layer is larger than the mass of the first metal oxide fine particles, it is determined that the mixed layer is contained in the low refractive index layer. When the mixed layer contains the first metal oxide fine particles and the second metal oxide fine particles in the same amount, it is determined that the mixed layer is included in the high refractive index layer.

The metal oxide concentration profile of the reflective layer formed by alternately laminating the high refractive index layer and the low refractive index layer according to the present invention is etched from the surface to the depth direction using a sputtering method, and an XPS surface analyzer , The outermost surface is set to 0 nm, sputtering is performed at a speed of 0.5 nm / min, and the atomic composition ratio can be measured. It is also possible to view the cut surface by cutting the laminated film and measuring the atomic composition ratio with an XPS surface analyzer. When the concentration of the metal oxide changes discontinuously in the mixed region, the boundary can be found by a tomographic photograph using an electron microscope (TEM).

The XPS surface analyzer is not particularly limited, and any model can be used, but ESCALAB-200R manufactured by VG Scientific Fix Co. was used. Mg is used for the X-ray anode, and measurement is performed at an output of 600 W (acceleration voltage: 15 kV, emission current: 40 mA).
(Lowermost layer)
This invention has the characteristics in the structure of the refractive index layer (lowermost layer) which touches a base material among the refractive index layers which comprise a reflection layer. That is, the lowermost layer contains an emulsion resin and has a feature that the thickness is 1.2 to 8 times the average thickness of the refractive index layer (other layers) other than the lowermost layer constituting the reflective layer. Have. When the lowermost layer contains the emulsion resin, the coating film is softened and curling can be suppressed. In addition, since the lowermost layer is 1.2 to 8 times thicker than the average thickness of the other layers, the lowermost layer forms a flexible film with a certain strength and curls when drying the infrared shielding film. Can be suppressed. As a result, the problem of sticking the infrared shielding film to the substrate and the generation of cracks can be prevented, and the visible light transmittance and infrared shielding property of the infrared shielding film can be suppressed from decreasing.

The lowermost layer containing the emulsion has a thickness 1.2 to 8 times, preferably 2 to 6 times the thickness of the refractive index layer (other layers) other than the lowermost layer constituting the reflective layer. Thus, even when the reflective layer is formed by a coating method, the generation of streaks and unevenness in the reflective layer can be prevented or suppressed. In addition, it is preferable that the lowermost layer has a thickness of 1.2 times or more than the average thickness of the other layers because an effect of curling suppression can be expected and the lowermost layer has a certain strength. It is preferable that the lowermost layer has a thickness of 8 times or less than the average thickness of the other layers because the coating properties are satisfactory and the cloudiness of the film can be suppressed. The “other layer” means all refractive index layers other than the lowermost layer located on the side where the lowermost layer of the substrate is provided. Therefore, when the refractive index layer is formed on the side opposite to the side on which the lowermost layer is provided (when the refractive index layer is formed on both sides of the base material), the opposite refractive index layer becomes the “other layer”. Shall not be included. Since the thickness of the lowermost layer is compared with the average thickness of other layers constituting the reflective layer, the other layers may include a layer thicker than the lowermost layer.

The emulsion resin that can be applied to the present invention is usually a resin formed by fusing a polymer dispersed in an aqueous solvent during the formation of the lowermost layer in the production process of the infrared shielding film. An emulsion as a raw material for the emulsion resin is obtained by emulsion polymerization of an oil-soluble monomer using a polymer dispersant or the like.

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

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

Further, the dispersant that can be used is not particularly limited, but in addition to a low-molecular dispersant such as alkyl sulfonate, alkyl benzene sulfonate, diethylamine, ethylenediamine, quaternary ammonium salt, polyoxyethylene nonylphenyl ether. , Polymer dispersing agents such as polyoxyethylene lauryl ether, hydroxyethyl cellulose, and polyvinylpyrrolidone.

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

The content of the emulsion resin in the lowermost layer is preferably 0.5 to 20% by mass, and more preferably 1 to 10% by mass with respect to the total mass of the lowermost layer. Further, regarding the relationship with the water-soluble resin contained in the lowermost layer, the water-soluble resin is preferably contained in a mass 1 to 10 times that of the emulsion. When the film forming step is obtained and dried, the structure of the water-soluble resin is maintained. Therefore, it is preferable that the water-soluble resin is contained in an amount equal to or greater than that of the emulsion resin because the film-forming property during production is excellent.

The lowermost layer may be a low refractive index layer or a high refractive index layer, but is preferably a low refractive index layer from the viewpoint of adhesion to the substrate.

(Refractive index layer in contact with the bottom layer)
The refractive index layer (second layer from the base material) in contact with the lowest layer is a refractive index layer having a refractive index different from that of the lowest layer (for example, if the lowest layer is a low refractive index layer, it becomes a high refractive index layer). . The specific configuration is as described above. From the viewpoint of suppressing aggregation between the metal oxide fine particles contained in the lowermost layer and the metal oxide fine particles contained in the refractive index layer in contact with the lowermost layer, the lowest. It is more preferable to control the structure of the water-soluble resin applied to the refractive index layer in contact with the lower layer.

Specifically, in one embodiment, the refractive index layer in contact with the lowermost layer preferably contains at least two water-soluble resins. By using at least two types of water-soluble resins in combination, the metal oxide fine particles can be stabilized and aggregation and the like can be suppressed, and properties such as cracks and haze can be improved.

The average degree of polymerization of one of the at least two water-soluble resins is preferably 100 to 700, more preferably 200 to 500. The water-soluble resin is preferably polyvinyl alcohol from the viewpoint of adsorptivity, and particularly preferably modified polyvinyl alcohol from the viewpoint of transparency and stabilization. Furthermore, the polyvinyl alcohol preferably has a saponification degree of 95% or more.

The other water-soluble resin of the at least two water-soluble resins preferably has an average degree of polymerization of 1500 to 5000, more preferably 2000 to 4000. The water-soluble resin is preferably polyvinyl alcohol, and preferably unmodified polyvinyl alcohol from the viewpoint of applicability. Further, the polyvinyl alcohol preferably has a saponification degree of 85 to 99.5%.

By applying the above water-soluble resin, the transparency of the film can be ensured and haze can be reduced. Since the lowermost layer contains an emulsion resin, aggregation between layers (hydroxy derived from the metal oxide fine particles) due to the reaction between the first metal oxide fine particles and the second metal oxide fine particles than the other layers. Aggregation based on groups is likely to occur. On the other hand, when the refractive index layer in contact with the lowermost layer contains the water-soluble resin according to the above-described preferred embodiment, the occurrence of such aggregation can be suppressed.

[Infrared shielding film manufacturing method]
There is no restriction | limiting in particular about the manufacturing method of the infrared shielding film of this invention, What kind of method can be used if a reflective layer which reflects an infrared light at least on a base material can be formed.

The infrared shielding film according to an embodiment of the present invention is preferably formed by alternately applying a high refractive index layer and a low refractive index layer on a substrate and drying the laminate. Specific examples include: (1) A high refractive index layer coating solution is applied on a substrate and dried to form a high refractive index layer, and then a low refractive index layer coating solution is applied. And then drying to form a low refractive index layer to form an infrared shielding film; (2) After applying a low refractive index layer coating solution on a substrate and drying to form a low refractive index layer A method for forming a high refractive index layer by applying a coating solution for a high refractive index layer and drying; and (3) forming an infrared shielding film; and (3) a coating solution for a high refractive index layer and a low refractive index on a substrate. A method of forming an infrared shielding film including a high refractive index layer and a low refractive index layer by alternately applying successive coating layers with the coating liquid for the refractive index layer and then drying; (4) a high refractive index layer on the substrate A method of forming an infrared shielding film including a high refractive index layer and a low refractive index layer; And the like. Among these, the method (4), which is a simpler manufacturing process, is preferable.

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.

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

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

The concentration of the water-soluble resin in the coating solution for the high refractive index layer is preferably 1 to 10% by mass. The concentration of the metal oxide fine particles in the coating solution for the high refractive index layer is preferably 1 to 50% by mass.

The concentration of the water-soluble resin in the coating solution for the low refractive index layer is preferably 1 to 10% by mass. The concentration of the metal oxide fine particles in the coating solution for the low refractive index layer is preferably 1 to 50% by mass.

The method for preparing the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is not particularly limited. For example, metal oxide fine particles, a water-soluble resin, and other additives added as necessary are added. And stirring and mixing. At this time, the order of addition of the respective components is not particularly limited, and the respective components may be sequentially added and mixed while stirring, or may be added and mixed at one time while stirring. If necessary, it is further adjusted to an appropriate viscosity using a solvent.

In the present invention, the lowermost layer essentially contains an emulsion resin. The emulsion resin may be contained in layers other than the lowermost layer, but from the viewpoint of transparency and haze, the content of the emulsion resin in the film is preferably small. In a preferred embodiment, the emulsion resin is contained only in the lowermost layer, and in this case, the coating solution for the high refractive index layer or the coating solution for the low refractive index layer that is the lowermost layer needs to be prepared separately. The average particle size of the emulsion in the coating solution for low refractive index layer or the coating solution for high refractive index layer containing the emulsion is preferably 10 to 200 nm, and more preferably 10 to 50 nm. When the emulsion has the above average particle diameter, an infrared shielding film excellent in transparency and haze can be obtained. The average particle size of the emulsion is measured using a dynamic light scattering method.

The viscosity of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer at the time of simultaneous multilayer coating is preferably 5 to 100 mPa · s when the slide bead coating method is used. More preferably, it is 50 mPa · s. When the curtain coating method is used, it is preferably 5 to 1200 mPa · s, and more preferably 25 to 500 mPa · s.

The viscosity of the coating solution at 15 ° C. is preferably 100 mPa · s or more, more preferably 100 to 80,000 mPa · s, and further preferably 3,000 to 80,000 mPa · s. Preferably, it is 10,000 to 80,000 mPa · s.

In the simultaneous overlap coating, for example, in the case where 9 layers simultaneous multilayer coating is repeatedly performed, the upper layer and the lower layer (first layer and ninth layer) of the 9 layers are preferably low refractive index layers. Since the low refractive index layer having metal oxide fine particles (silicon oxide) is excellent in adhesiveness, for example, when the ninth layer is a low refractive index layer at the time of simultaneous multilayer coating in one pass, This is preferable because of excellent adhesion between the substrate and the lower refractive index layer as the lower layer. In the simultaneous multi-layer coating at the time of two passes, a low refractive index layer as a lower layer (9th layer) at the time of two passes is laminated on a low refractive index layer that is an upper layer (first layer) at the time of one pass. It is preferable because it is excellent in adhesiveness.

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

[Infrared shield]
The infrared shielding film provided by 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, films for window pasting such as infrared shielding films that give an infrared shielding effect, films for agricultural greenhouses, etc. As, it is mainly used for the purpose of improving the weather resistance.

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

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

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

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

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

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

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

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

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

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

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" is used in an Example, unless otherwise indicated, "mass part" is represented.

Example 1
1. Preparation of Coating Solution 1 for Low Refractive Index Layer 9.18 parts of a 23.5 mass% aqueous solution of polyaluminum chloride (Taki Chemical Co., Ltd., Takibaine # 1500) and 215 parts of colloidal silica (Snowtex OXS, average) Particle size: 5 nm, manufactured by Nissan Chemical Industries, Ltd.), 10 parts by weight aqueous solution, 23 parts by weight of 3.0% by weight aqueous solution of boric acid, and 8.4 parts by weight of 3.3% by weight aqueous solution of sodium acetate. It mixed and disperse | distributed and finished to 400 parts with pure water, and the silicon oxide dispersion liquid was prepared.

Next, the silicon oxide dispersion was heated to 45 ° C. and 4 parts of 8 parts of pure water and 188 parts of unmodified polyvinyl alcohol (PVA235, polymerization degree: 3500, saponification degree: 88%, manufactured by Kuraray Co., Ltd.). After adding and mixing 0% by weight solution and 12.5 parts of cationic emulsion (UW-319SX, average particle size: 50 nm, Tg: 10 ° C., Taisei Fine Chemical Co., Ltd.) Further, 1.90 parts of 5% CA-3475V (manufactured by Nikko Chemicals Co., Ltd.) was added as a cationic surfactant to prepare a coating solution 1 for a low refractive index layer.

2. Preparation of coating solution 2 for low refractive index layer A coating solution 2 for low refractive index layer was prepared in the same manner as in 1 above, except that water was used instead of the cationic emulsion.

3. Preparation of Coating Solution 1 for High Refractive Index Layer 20 parts of AZF8035W (modified PVA, degree of polymerization: 300, degree of saponification: 98.5%, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) A 20.0 mass% titanium oxide sol containing rutile-type titanium oxide fine particles (volume average particle diameter: 35 nm) was mixed and dispersed, and finished with 90 parts of pure water to prepare a titanium oxide dispersion.

Next, 30 parts of 5% PVA224 (degree of polymerization: 2400, degree of saponification: 88%, manufactured by Kuraray Co., Ltd.) is added to and mixed with the titanium oxide dispersion, and 0.20 part as a cationic surfactant. 5% CA-3475V (manufactured by Nikko Chemicals Co., Ltd.) was added, and finally it was finished to 180 parts with pure water to prepare a coating solution 1 for a high refractive index layer.

4). Preparation of Infrared Shielding Film A polyethylene terephthalate film having a thickness of 50 μm heated to 45 ° C. while keeping the coating solution 1 for low refractive index layer prepared in 1 above at 45 ° C. (Toyobo A4300: double-sided easy adhesion layer) A wire bar was applied on top. Immediately after that, cold air was blown for 1 minute under conditions where the film surface was 15 ° C. or lower, and then hot air of 80 ° C. was blown to dry. Next, the same application is repeated using the coating solution 2 for the low refractive index layer and the coating solution 1 for the high refractive index layer prepared in 2 and 3 above, and the low refractive index layer and the high refractive index layer are alternately laminated. Thus, a total of 21 layers including the lowermost layer were formed.

The dry thickness of the prepared infrared shielding film was 350 nm for the lowermost layer and 170 nm for the other layers. In the infrared shielding film, the lowermost layer is a low refractive index layer, and the outermost layer is also a low refractive index layer.

(Example 2)
An infrared shielding film was produced in the same manner as in Example 1 except that AZF8035W (modified PVA) was not added to the coating solution 1 for the high refractive index layer used for forming the layer in contact with the lowermost layer.

(Example 3)
The same as Example 1 except that the amount of the 4.0% by mass solution of unmodified polyvinyl alcohol (PVA235, manufactured by Kuraray Co., Ltd.) contained in the coating solution 1 for the low refractive index layer was changed to 94 parts. Thus, an infrared shielding film was produced.

(Example 4)
An infrared shielding film was produced in the same manner as in Example 1 except that the amount of the cationic emulsion contained in the coating solution 1 for the low refractive index layer was changed to 2.3 parts.

(Example 5)
Except that AZF8035W contained in the coating liquid 1 for the high refractive index layer was changed to PVA103 (degree of polymerization: 300, degree of saponification: 98.4%, manufactured by Kuraray Co., Ltd.), the same as in Example 1. Thus, an infrared shielding film was produced.

(Example 6)
Except that the PVA 224 contained in the coating solution 1 for the high refractive index layer was changed to PVA 210 (polymerization degree: 1000, saponification degree: 88%, manufactured by Kuraray Co., Ltd.), the same infrared ray as in Example 1 was used. A shielding film was produced.

(Example 7)
The cationic emulsion contained in the coating solution 1 for the low refractive index layer and the coating solution 2 for the low refractive index layer was changed to an acrylic emulsion (SX1706, particle size: 100 nm, Tg: 0 ° C., manufactured by Zeon Corporation). Except for, an infrared shielding film was prepared in the same manner as in Example 1.

(Example 8)
An infrared shielding film was produced in the same manner as in Example 1 except that the film thickness of the lowermost layer was changed to 765 nm.

Example 9
An infrared shielding film was produced in the same manner as in Example 1 except that the film thickness of the lowermost layer was changed to 1190 nm.

(Comparative Example 1)
An infrared shielding film was produced in the same manner as in Example 1 except that the coating solution 2 for low refractive index layer 2 was used instead of the coating solution 1 for low refractive index layer.

(Comparative Example 2)
An infrared shielding film was produced in the same manner as in Example 1 except that the film thickness of the lowermost layer was changed to 170 nm.

(Comparative Example 3)
An infrared shielding film was produced in the same manner as in Example 1 except that the film thickness of the lowermost layer was changed to 1445 nm.

(Comparative Example 4)
An infrared shielding film was produced in the same manner as in Example 1 except that the thickness of the lowermost layer was changed to 1700 nm.

Table 1 shows the infrared shielding films produced in Examples 1 to 9 and Comparative Examples 1 to 4.

[Evaluation of infrared shielding film]
The following performance evaluation was performed about each infrared shielding film produced above.

<Measurement of refractive index of each layer / calculation of refractive index difference>
Samples were prepared by coating each layer (high refractive index layer, low refractive index layer) on which the refractive index was measured on a substrate (PET film), and the refractive index was determined according to the following method. .

A spectrophotometer U-4000 type (manufactured by Hitachi, Ltd.) was used. After roughening the back side of the measurement side of each sample, light absorption treatment is performed with a black spray to prevent reflection of light on the back side, and in the visible light region (400 nm to The refractive index was determined from the measurement result of the reflectance at 700 nm. And the refractive index difference was computed from the obtained refractive index.

<Measurement of haze value: Evaluation of surface uniformity>
The haze value was measured using a haze meter (Nippon Denshoku Industries Co., Ltd., NDH2000). Surface uniformity was evaluated according to the following criteria.

○: 1% or less △: Over 1% to 2% or less △△: Over 2% to 3% or less ×: Over 3%.

<Measurement and evaluation of visible light transmittance and infrared transmittance>
Using a spectrophotometer (using an integrating sphere, manufactured by Hitachi, Ltd., U-4000 type), the transmittance of each infrared shielding film in the region of 300 nm to 2000 nm was measured. The visible light transmittance was a transmittance value at 550 nm, and the infrared transmittance was a transmittance value at 1200 nm.

<Crack>
The produced infrared shielding film was cut into a size of 210 mm × 297 mm. The cut infrared shielding film was visually observed, and cracks were evaluated according to the following criteria.

○: No crack is observed Δ: 1 to 2 cracks are observed ΔΔ: 3 to 10 cracks are observed ×: 11 or more cracks are observed

<Measurement and evaluation of curls>
The infrared shielding film was cut into a size of 10 × 10 cm, and the height of the four corners of the curl immediately after heating for 1 minute in an oven at 80 ° C. was measured, and the average value was evaluated.

○: 1 cm or less Δ: Over 1 cm to 2 cm or less ΔΔ: Over 2 cm to 3 cm or less x: Over 3 cm.

<Evaluation of coatability>
The produced infrared shielding film was cut into a size of 210 mm × 297 mm. The cut infrared shielding film was visually observed, and the presence or absence of streaks and unevenness was evaluated according to the following criteria.

○: No streaks or unevenness is observed Δ: Streaks or unevenness is observed below 5% Δ △: Streaks or unevenness is observed below 5% to 10% ×: Streaks or unevenness is observed above 10% .

The evaluation results obtained are shown in Table 2 below.

In the infrared shielding films produced in Examples 1 to 9, curling was suppressed and cracking hardly occurred even with a relatively thin film of 21 layers. Further, even when the lowermost layer was thick and the emulsion resin was included, the visible light transmittance and the infrared shielding property were excellent. Furthermore, the generation of streaks and unevenness was prevented, and the coating property was excellent.

Claims

An infrared shielding film having a base material and a reflective layer that reflects at least infrared light,
The reflective layer has a plurality of laminated refractive index layers,
At least one of the refractive index layers has a refractive index different from that of an adjacent refractive index layer;
Of the refractive index layers constituting the reflective layer, the lowermost layer in contact with the substrate contains metal oxide fine particles and an emulsion resin, and the lowermost layer is an average of the refractive index layers other than the lowermost layer. An infrared shielding film having a thickness of 1.2 to 8 times the thickness.
The infrared shielding film according to claim 1, wherein the refractive index layer in contact with the lowermost layer contains at least two water-soluble resins.
The infrared shielding film according to claim 2, wherein the refractive index layer in contact with the lowermost layer contains a water-soluble resin having an average polymerization degree of 500 or less and a water-soluble resin having an average polymerization degree of 2000 or more.
The infrared shielding film according to claim 3, wherein the water-soluble resin having an average degree of polymerization of 2000 or more is unmodified polyvinyl alcohol.
The infrared shielding film according to claim 3 or 4, wherein the water-soluble resin having an average polymerization degree of 500 or less is a modified polyvinyl alcohol.
The infrared shielding film according to any one of claims 1 to 5, wherein the lowermost layer further contains a water-soluble resin having a mass of 1 to 10 times that of the emulsion resin.
The method for producing an infrared shielding film according to any one of claims 1 to 6, comprising a step of forming the emulsion resin using an emulsion having an average particle size of 50 nm or less.
An infrared shielding body comprising the infrared shielding film according to any one of claims 1 to 6 or the infrared shielding film obtained by the production method according to claim 7 on at least one surface of a substrate.