JPWO2014185386A1 - Infrared shielding film manufacturing method - Google Patents

Abstract

The present invention provides a method for producing an infrared shielding film having a good appearance with little or no color unevenness, streak failure, and grainy unevenness due to high uniformity in the width direction. For the purpose. In the present invention, a coating solution for a high refractive index layer and a coating solution for a low refractive index layer are simultaneously applied on a continuously running base film using a slide hopper type coating apparatus. A method for producing an infrared shielding film including a step of applying multiple layers, wherein the high refractive index layer coating liquid and the low refractive index layer coating liquid have a viscosity at 45 ° C. of 5 to 200 mPa · s, and the slide It is a manufacturing method of the infrared shielding film whose thickness per block of a hopper type coating device is 25-50 mm. [Selection figure] None

Description

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

  Conventionally, multilayer laminated films such as an antireflection film, an infrared shielding film, and a color photosensitive material are manufactured by dry film formation or wet film formation. In terms of productivity, wet film formation in which application liquid is applied and dried is superior to dry film formation such as chemical vapor deposition (CVD) and physical vapor deposition (PVD).

  The slide hopper type coating apparatus is suitably used for the production of the multilayer laminated film as described above as a wet film forming apparatus capable of simultaneously applying a plurality of coating liquids. There is a need for a method.

  Japanese Patent Application Laid-Open No. 2009-28604 discloses a distance (hereinafter referred to as a slit portion) from a portion (hereinafter referred to as a chamber) that spreads the coating liquid in the slide hopper coating device in the width direction of the base film to the coating width. A manufacturing method is disclosed in which the uniformity in the width direction is improved by making the length of 40 mm or more. According to this manufacturing method, it is possible to provide a small and light slide hopper type coating apparatus with high uniformity in the width direction.

  However, since the coating liquid used for the production of the infrared shielding film is a combination of a low-viscosity liquid and a high-viscosity liquid, and the flow rates of the adjacent coating liquids are substantially the same, the above-mentioned JP-A-2009-28604 When applying technology and performing multi-layer coating, the hydraulic pressure inside the slide hopper type coating device is different, so the block is deformed, and the desired base film width direction uniformity cannot be obtained. there were.

  Therefore, since the present invention has high uniformity in the width direction of the base film, there is no color unevenness, and furthermore, a method for producing an infrared shielding film having a good appearance that can suppress streak failure and grainy unevenness. The purpose is to provide.

  The present inventors have conducted intensive studies in view of the above problems. As a result, it has been surprisingly found that the above-mentioned problems can be solved by setting the thickness per block of the slide hopper coating apparatus within a specific range. As a result, the present invention has been completed.

  That is, according to the present invention, a coating solution for a high refractive index layer and a coating solution for a low refractive index layer are applied on a substrate film that runs continuously using a slide hopper type coating apparatus. A method for producing an infrared shielding film comprising a step of simultaneously applying multiple layers, wherein the coating liquid for high refractive index layer and the coating liquid for low refractive index layer have a viscosity at 40 ° C. of 5 to 200 mPa · s, It is a manufacturing method of the infrared shielding film whose thickness per block of the said slide hopper type coating device is 25-50 mm.

It is the schematic which shows an example of a slide hopper type coating device.

Explanation of symbols in FIG.
1 base film,
2 Back roll,
3 Coater dice,
4 Coating liquid,
5 vacuum chamber,
6 Wetted parts,
7 Angle (γ) between back roll center and wetted part,
8 Angle (β) of the slide surface with respect to the horizontal plane,
9 Angle (α) between the running surface of the base film and the sliding surface,
10 decompression section,
11 blocks,
t Block thickness.

  Hereinafter, the manufacturing method of the infrared shielding film of this invention is demonstrated in detail.

  FIG. 1 is a schematic view showing an example of a slide hopper type coating apparatus used in the present invention.

  The base film 1 that is continuously transported is held by the back roll 2 that rotates in the same direction in accordance with the transport speed of the base film 1 that is at the position facing the coater die 3, and the wetted part 6 Is applied. The coater die 3 is composed of a plurality of blocks (FIG. 1 shows a form of simultaneous application of four layers), and the coating liquid 4 flows down on the coater die 3. The coater die 3 is fixed to a coater die holding base (not shown) at an angle 8 (β) with respect to a horizontal plane of a fixed slide surface. A decompression chamber 5 is provided at the lower part between the back roll 2 and the coater die 3. In order to stabilize the bead formed in the liquid contact part 6, the decompression chamber 5 is evacuated from the decompression part 10 in order to depressurize the bead, specifically, the lower part of the bead. Is a negative pressure.

  In the present invention, the thickness per block of the slide hopper type coating apparatus shown in FIG. Thereby, the uniformity in the width direction is improved, the occurrence of color unevenness in the width direction of the coated surface, streak failure, and grain-like unevenness can be suppressed, and an infrared shielding film having a good appearance is obtained. Can do. In the present invention, the thickness per block is the distance indicated by t in FIG.

  In the slide hopper type coating apparatus, the flow of the coating solution supplied to the central portion is spread in the width direction of the base film at a portion called a chamber and flows out from the portion called a slit to the slide surface. At this time, it is necessary to make the fluid resistance of the slit portion sufficiently large, and as a result, the flow in the width direction is made uniform by increasing the length of the slit. In the method for producing the infrared shielding film of the present invention, a high-viscosity liquid and a low-viscosity liquid are used in combination. , The portion where the high-viscosity liquid that is adjacent flows is largely different from the portion that flows the low-viscosity liquid. Therefore, even if the length of the slit of each block is long, deformation of the slit occurs and the uniformity in the width direction of the base film is impaired, so the thickness per block needs to be 25 mm or more. is there. However, when the thickness per block exceeds 50 mm, the length of the slide surface becomes long, so that the coating liquid undulates on the slide surface, and the grainy unevenness caused by the undulations occurs. For this reason, by setting the thickness per block to 25 to 50 mm, the uniformity in the width direction of the base film is high. An infrared shielding film having a good appearance can be obtained with little or no unevenness.

  In addition, said mechanism is based on estimation and this invention is not restrict | limited to the said mechanism at all.

  Hereinafter, the manufacturing method of the infrared shielding film of this invention is demonstrated in detail.

[Infrared shielding film]
The configuration of the infrared shielding film according to the present invention is not particularly limited, but preferably includes a base film and at least one unit composed of a high refractive index layer and a low refractive index layer. It is more preferable to have a form of an alternating laminate in which layers and low refractive index layers are alternately laminated. In the present specification, a refractive index layer having a higher refractive index than the other is referred to as a high refractive index layer, and a refractive index layer having a lower refractive index than the other is referred to as a low refractive index layer.

  In the present invention, the infrared shielding film preferably includes at least one unit composed of two layers having different refractive indexes, that is, a high refractive index layer and a low refractive index layer. For example, when each of the high refractive index layer and the low refractive index layer contains metal oxide particles, the metal oxide particles contained in the low refractive index layer (hereinafter referred to as “first metal oxide particles”), Metal oxide particles (hereinafter referred to as “second metal oxide particles”) contained in the high refractive index layer are mixed at the interface between the two layers, and the first metal oxide particles and the second metal are mixed. A layer containing oxide particles may be formed. In that case, it is regarded as a low refractive index layer or a high refractive index layer depending on the abundance ratio of the first metal oxide particles and the second metal oxide particles. Specifically, the low refractive index layer means that the first metal oxide particles are 50 to 100% by mass with respect to the total mass of the first metal oxide particles and the second metal oxide particles. Means the layers involved. The high refractive index layer means that the second metal oxide particles are more than 50% by mass and less than 100% by mass with respect to the total mass of the first metal oxide particles and the second metal oxide particles. Means the layers involved. The type and amount of metal oxide particles contained in the refractive index layer can be analyzed by energy dispersive X-ray spectroscopy (EDX).

The metal oxide particles used in the present invention is not particularly limited, titanium oxide _(TiO 2), zinc oxide (ZnO), zirconium oxide _(ZrO 2), niobium oxide _{(Nb 2 O} 5), aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), calcium fluoride (CaF ₂ ), magnesium fluoride (MgF ₂ ), indium tin oxide (ITO), antimony tin oxide (ATO), and the like. Among these, titanium oxide (TiO ₂ ) is used as the second metal oxide particles contained in the coating solution for the high refractive index layer, and silicon oxide is used as the first metal oxide particles contained in the coating solution for the low refractive index layer. It is preferable to use (SiO ₂ ), respectively.

  Further, the titanium oxide particles may be coated with a silicon-containing hydrated oxide. The coating amount of the silicon-containing hydrated compound is preferably 3 to 30% by mass, more preferably 3 to 10% by mass, and further preferably 3 to 8% by mass. This is because 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.

As a method of coating titanium oxide particles with a silicon-containing hydrated oxide, it can be produced by a conventionally known method. For example, JP-A-10-158015 (Si / Al hydration to rutile titanium oxide) Oxide treatment; a method of producing a titanium oxide sol in which a hydrous oxide of silicon and / or aluminum is deposited on the surface of titanium oxide after peptization in the alkaline region of the titanate cake), JP 2000-204301 A (A sol in which a rutile titanium oxide is coated with a complex oxide of Si and Zr and / or Al. Hydrothermal treatment), JP 2007-246351 (Oxidation obtained by peptizing hydrous titanium oxide) titanium to hydrosol, wherein ^R _{1 n SiX 4-n} (wherein ^{R 1} is C1-C8 alkyl group as a stabilizer, glycidyloxy substituted C1-C8 A compound having a complexing action with respect to an organoalkoxysilane or titanium oxide of an alkyl group or a C2-C8 alkenyl group, X is an alkoxy group, and n is 1 or 2. Sodium silicate or silica sol in an alkali region is added. The method described in, for example, a method for producing a titanium oxide hydrosol coated with a hydrous oxide of silicon by adding, pH adjusting, and aging to the above solution can be referred to.

  In general, in an infrared shielding film, it is preferable to design a large difference in refractive index between a low refractive index layer and a high refractive index layer from the viewpoint that the infrared reflectance can be increased with a small number of layers. In the infrared shielding film according to the present invention, in at least one of the units composed of the low refractive index layer and the high refractive index layer, the refractive index difference between the adjacent low refractive index layer and the high refractive index layer is 0.1. Preferably, it is 0.3 or more, more preferably 0.35 or more, and particularly preferably 0.4 or more. When the infrared shielding film has a plurality of units of a high refractive index layer and a low refractive index layer, the refractive index difference between the high refractive index layer and the low refractive index layer in all the units is within the preferred range. Is preferred. However, regarding the outermost layer and the lowermost layer, a configuration outside the above preferred range may be used. Moreover, in the infrared shielding film of this embodiment, the preferable refractive index of a low refractive index layer is 1.10-1.60, More preferably, it is 1.30-1.50. Moreover, the preferable refractive index of a high refractive index layer is 1.80-2.50, More preferably, it is 1.90-2.20.

  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 the refractive index is coated as a single layer on a base film 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, after roughening the back side on the measurement side of each sample, light absorption treatment is performed with a black spray to reduce the light on the back side. The reflection is prevented, 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, the average value is obtained, and the average refractive index is obtained from the measurement result.

  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 less than 0.1, it is necessary to laminate 200 layers or more, which not only decreases productivity but also scattering at the interface of the layers. Becomes larger, the transparency is lowered, and it becomes very difficult to manufacture without failure. 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.

  The number of layers of the infrared shielding film according to the present invention is 10 or more and 40 or less, preferably 10 or more and 25 or less, and more preferably 15 or more and 25 or less. In addition, the infrared shielding film of the present invention may be, for example, a laminated film in which either the outermost layer or the lowermost layer of the laminated film is a high refractive index layer or a low refractive index layer. The infrared shielding film according to the present invention preferably has a layer structure in which the lowermost layer adjacent to the base film is a low refractive index layer and the outermost layer is also a low refractive index layer.

  The total thickness of the infrared shielding film according to the present invention is preferably 12 μm to 315 μm, more preferably 15 μm to 200 μm, and still more preferably 20 μm to 150 μm. Moreover, it is preferable that the thickness per layer of a low-refractive-index layer except a lowermost layer is 20-500 nm, and it is more preferable that it is 50-300 nm. On the other hand, the thickness per layer of the high refractive index layer is preferably 20 to 500 nm, and more preferably 50 to 300 nm. The thickness of the lowermost layer is preferably 300 to 1500 nm, and more preferably 400 to 1200 nm.

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

  The infrared shielding film according to the present invention has a conductive layer, an antistatic layer, a gas barrier layer, an easy layer for the purpose of adding further functions under the base film or on the outermost surface layer opposite to the base film. Adhesive layer (adhesive layer), antifouling layer, deodorant layer, droplet layer, slippery layer, hard coat layer, wear-resistant layer, antireflection layer, electromagnetic wave shielding layer, ultraviolet absorption layer, infrared absorption layer, printing layer , Fluorescent light emitting layer, hologram layer, release layer, adhesive layer, adhesive layer, infrared cut layer (metal layer, liquid crystal layer) other than the high refractive index layer and low refractive index layer of the present invention, colored layer (visible light absorbing layer) In addition, one or more functional layers such as an interlayer film used for laminated glass may be included.

[Infrared shielding film manufacturing method]
The coating solution used in the present invention is applied by simultaneous multi-layer coating using a slide hopper coating device, and a base film is formed by laminating a coating solution for high refractive index and a coating solution for low refractive index on the slide surface. The high refractive index layer and the low refractive index layer are formed by applying to the film.

(Method for preparing coating solution)
Here, a method for preparing a coating solution for a high refractive index layer and a coating solution for a low refractive index layer will be described.

  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 particles, a water-soluble polymer, and other additives that are added as necessary. The method of adding and stirring and mixing is mentioned. 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.

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

  Examples of the organic solvent include alcohols such as methanol, ethanol, 2-propanol and 1-butanol, esters such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate, diethyl ether, Examples thereof include ethers such as propylene glycol monomethyl ether and ethylene glycol monoethyl ether, amides such as dimethylformamide and N-methylpyrrolidone, and ketones such as acetone, methyl ethyl ketone, acetylacetone and cyclohexanone. These organic solvents may be used alone or in combination of two or more.

  From the viewpoint of environment and simplicity of operation, the solvent for the coating solution is particularly preferably water or a mixed solvent of water and methanol, ethanol, or ethyl acetate.

  In addition, it is preferable to use what was prepared in the state of the dispersion liquid separately before preparing a coating liquid as the 2nd metal oxide particle used for the coating liquid for high refractive index layers. That is, it is preferable to form the high refractive index layer using an aqueous high refractive index coating solution prepared by adding and dispersing rutile type titanium oxide having a volume average particle size of 100 nm or less. Furthermore, it is more preferable to form the high refractive index layer using an aqueous coating solution for high refractive index layer prepared by adding and dispersing titanium oxide particles coated with a silicon-containing hydrated oxide. In the case of using a dispersion liquid, the dispersion liquid may be appropriately added so as to have an arbitrary concentration in each layer.

  In the present invention, as the coating solution for the low refractive index layer and the coating solution for the high refractive index layer, a coating film can be set after coating, and mixing between layers can be suppressed. It is preferable to use water or an aqueous coating solution containing water and an aqueous solvent containing a water-soluble organic solvent.

  The viscosity at 40 ° C. of the coating solution for high refractive index layer and the coating solution for low refractive index layer is 5 to 200 mPa · s, preferably 20 to 180 mPa · s. When the viscosity is less than 5 mPa · s, the dynamic pressure of the slide surface flow is insufficient, resulting in streak failure. On the other hand, if it exceeds 200 mPa · s, deformation of the block occurs even if the thickness per block is 25 to 50 mm, the uniformity in the substrate film width direction is impaired, and color unevenness is observed.

  The concentration of the solid content of the coating solution is preferably 0.1 to 10% by mass, and more preferably 0.1 to 5% by mass. This is because in this range, the solid content is low and the uniformity of the coating solution is high, so that the film thickness uniformity is considered to be further improved.

  The concentration of the water-soluble polymer in the coating solution for the low refractive index layer is preferably 0.1 to 10% by mass. Moreover, it is preferable that the density | concentration of the 1st metal oxide particle in the coating liquid for low refractive index layers is 1-60 mass%.

  The concentration of the water-soluble polymer in the coating solution for the high refractive index layer is preferably 0.5 to 10% by mass. Moreover, it is preferable that the density | concentration of the 2nd metal oxide particle in the coating liquid for high refractive index layers is 1-60 mass%.

  In the production method of the present invention, the coating speed is preferably 40 to 250 m / min, more preferably 60 to 200 m / min, and particularly preferably 80 to 150 m / min. According to the production method of the present invention, an infrared shielding film excellent in appearance can be obtained even at such a high speed.

Moreover, especially the coating amount of the said coating liquid for high refractive index layers and the coating liquid for low refractive index layers except a lowermost layer is although it does not restrict | limit, It is preferable that it is 1-10 g / m < ² >. If it is this range, the effect of this invention will be acquired more efficiently. The coating amount is more preferably ² to 5 g / m ² . 5-45 g / m < ² > is preferable and, as for the application quantity of the lowest layer, 10-40 g / m < ² > is more preferable.

  Furthermore, as described above, in the manufacturing method of the present invention, the thickness per block of the slide hopper type coating apparatus is 25 to 50 mm. If the thickness per block is less than 25 mm, the viscosity of the adjacent layers will be different, so the fluid pressure in the slide hopper type coating device will be different in the adjacent layers and the block will be deformed. Uniformity of direction is impaired. In addition, when the thickness per block is more than 50 mm, undulations occur on the slide surface, and wood-like coating unevenness occurs. Moreover, from the viewpoint that the uniformity in the width direction of the base film can be maintained with respect to a wide range of liquid properties and coating amount, the thickness per block is preferably 30 to 50 mm. In addition, when performing simultaneous multilayer coating, the slide hopper type coating apparatus has a plurality of blocks, but the thickness of the plurality of blocks may be the same or different. However, the thickness of the plurality of blocks is preferably the same from the viewpoint of obtaining the effect of the present invention more efficiently and the viewpoint of simplifying the apparatus.

  In the drying method, the coating liquid for the high refractive index layer and the coating liquid for the low refractive index layer are heated to 30 to 60 ° C., and the coating liquid for the high refractive index layer and the coating liquid for the low refractive index layer are formed on the base film. After the simultaneous multilayer coating is performed, the temperature of the formed coating film is preferably cooled (set) to preferably 1 to 15 ° C. and then dried at 10 ° C. or higher. More preferable drying conditions are wet bulb temperature −10 to 50 ° C. and film surface temperature 10 to 50 ° C. For example, it is dried by blowing warm air of 50 ° C. for 1 to 5 minutes. Moreover, as a cooling method immediately after application | coating, it is preferable to carry out by a horizontal set system from a viewpoint of the uniformity improvement of the formed coating film.

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

  As a drying method, warm air drying, infrared drying, and microwave drying are used. In addition, drying in a multi-stage process is preferable to drying in a single process, and it is more preferable to set the temperature of the constant rate drying section <the temperature of the decremental drying section. In this case, the temperature range of the constant rate drying section is preferably 20 to 60 ° C, and the temperature range of the decreasing rate drying section is preferably 45 to 80 ° C.

  Here, the set means that the viscosity of the coating composition is increased by means such as lowering the temperature by applying cold air or the like to the coating film, the fluidity of the substances in each layer and in each layer is reduced, or the gel It means the process of making it. A state in which the cold air is applied to the coating film from the surface and the finger is pressed against the surface of the coating film is defined as a set completion state.

  The time (setting time) from the time of application to the completion of setting by applying cold air is preferably within 5 minutes, and more preferably within 2 minutes. Further, the lower limit time is not particularly limited, but it is preferable to take 30 seconds or more. If the set time is too short, mixing of the components in the layer may be insufficient. On the other hand, if the set time is too long, the interlayer diffusion of the metal oxide particles proceeds, and the refractive index difference between the high refractive index layer and the low refractive index layer may be insufficient.

[Water-soluble polymer]
Examples of the water-soluble polymer used in the present invention include polyvinyl alcohols, polyvinyl pyrrolidones, polyvinyl butyral, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate. -Acrylic resin such as acrylic ester copolymer or acrylic acid-acrylic ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic ester copolymer Styrene acrylic acid resin such as styrene-α-methylstyrene-acrylic acid copolymer, or styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer, styrene-sodium styrenesulfonate copolymer, styrene -2-hydroxy Ethyl acrylate copolymer, styrene-2-hydroxyethyl acrylate-potassium styrene sulfonate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene -Synthetic water such as maleic acid copolymers, vinyl acetate-maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate copolymers such as vinyl acetate-acrylic acid copolymers and their salts Natural water-soluble polymers such as gelatin and thickening polysaccharides. Among these, particularly preferred examples include polyvinyl alcohols, polyvinylpyrrolidones, and copolymers containing them, polyvinyl butyral, gelatin, thickening polysaccharides from the viewpoint of handling during production and film flexibility. (Especially celluloses). These water-soluble polymers may be used alone or in combination of two or more.

  The polyvinyl alcohol preferably used in the present invention includes modified polyvinyl alcohol in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate. Examples of the modified polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, nonion-modified polyvinyl alcohol, and vinyl alcohol polymers.

  Polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate preferably has an average degree of polymerization of 1,000 or more, particularly preferably an average degree of polymerization of 1,500 to 5,000, and 2,000 to 5,000 is more preferably used. This is because when the polymerization degree of polyvinyl alcohol is 1,000 or more, there is no cracking of the coating film, and when it is 5,000 or less, the coating solution is stable. In addition, that the coating solution is stable means that the coating solution is stabilized over time. The same applies hereinafter.

  The saponification degree is preferably 70 to 100%, more preferably 80 to 99.5% in view of solubility in water.

  In the present invention, in addition to the polyvinyl alcohol having an average polymerization degree of 1,000 or more, a low polymerization degree highly saponified polyvinyl alcohol having a polymerization degree of 100 to 500 and a saponification degree of 95 mol% or more is used. It is preferable that at least one of the low refractive index layers includes. By containing such a low polymerization degree highly saponified polyvinyl alcohol, the stability of the coating solution is improved.

  Furthermore, as long as the effect of the present invention is not impaired, at least one of the high refractive index layer and the low refractive index layer is modified in part other than normal polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate. Polyvinyl alcohol may be included. Examples of such modified polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, nonion-modified polyvinyl alcohol, and vinyl alcohol polymers.

  Examples of the cation-modified polyvinyl alcohol include primary to tertiary amino groups and quaternary ammonium groups, as described in JP-A No. 61-10383, in the main chain or side chain of the polyvinyl alcohol. It 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 described in, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-206088, JP-A-61-237681 and JP-A-63-307979. 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. Block copolymer of vinyl compound having a hydrophobic group and vinyl alcohol, silanol-modified polyvinyl alcohol having silanol group, reactive group modification having reactive group such as acetoacetyl group, carbonyl group, carboxyl group Polyvinyl alcohol etc. are mentioned.

  These polyvinyl alcohols may be used alone or in combination of two or more such as the degree of polymerization and the type of modification. As the polyvinyl alcohols, commercially available products or synthetic products may be used. Examples of commercially available products include, for example, PVA-102, PVA-103, PVA-105, PVA-110, PVA-117, PVA-120, PVA-124, PVA-135, PVA-203, PVA-205, PVA -210, PVA-217, PVA-220, PVA-224, PVA-235, PVA-617, etc. Poval (manufactured by Kuraray Co., Ltd.), EXEVAL (registered trademark, manufactured by Kuraray Co., Ltd.), Nichigo G polymer (registered trademark, Nippon Synthetic Chemical Industry Co., Ltd.).

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

<Curing agent>
In the low refractive index layer and the high refractive index layer according to the present invention, it is preferable to add a curing agent. Examples of the curing agent include a curing agent that causes a curing reaction with polyvinyl alcohol suitable as the water-soluble polymer. Specifically, boric acid and its salt are preferable. In addition to boric acid and its salts, known ones can be used, generally a compound having a group capable of reacting with polyvinyl alcohol or a compound that promotes the reaction between different groups possessed by polyvinyl alcohol, It is appropriately selected and used. Specific examples of other curing agents include, for example, epoxy curing agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N -Diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde-based curing agents (formaldehyde, glioxal, etc.), active halogen-based curing agents (2,4-dichloro-4-hydroxy-1, 3,5-s-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum and the like.

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

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

  The aqueous solutions of boric acid and borax can be added only in relatively dilute aqueous solutions, respectively, but by mixing them both can be made into a concentrated aqueous solution and the coating solution can be concentrated. Further, there is an advantage that the pH of the aqueous solution to be added can be controlled relatively freely.

  In the present invention, it is preferable to use boric acid and a salt thereof and / or borax from the viewpoint of further suppressing interlayer mixing. When boric acid salt and / or borax is used, the metal oxide particles and the OH group of polyvinyl alcohol, which is a water-soluble binder resin, form a hydrogen bond network, resulting in a high refractive index. It is thought that interlayer mixing between the layer and the low refractive index layer is suppressed, and preferable infrared shielding characteristics are achieved. In particular, when a multilayer coating of a high refractive index layer and a low refractive index layer is applied with a coater, the film surface temperature of the coating film is once cooled to about 15 ° C., and then the set surface coating process is used to dry the film surface. Can express an effect more preferably.

  The total amount of the curing agent used is preferably 1 to 600 mg per 1 g of polyvinyl alcohol, and more preferably 100 to 600 mg per 1 g of polyvinyl alcohol.

<Other additives>
Various additives that can be added to the coating solution for the high refractive index layer and the coating solution for the low refractive index layer according to the present invention are listed below. For example, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192, and JP-A-57-87989. , JP-A-60-72785, JP-A-61-14659, JP-A-1-95091, JP-A-3-13376, etc. Nonionic surfactants, JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-228771, and JP-A-4-219266 Whitening agent, sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, sodium acetate, etc. pH adjusters, antifoaming 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, reduction Various known additives such as a sticky agent, a lubricant, an infrared absorber, a dye, and a pigment can be used.

[Base film]
As the base film of the infrared shielding film, various resin films can be used. For example, polyolefin film (polyethylene, polypropylene, etc.), polyester film (polyethylene terephthalate, polyethylene naphthalate, etc.), polyvinyl chloride, 3 acetic acid A cellulose etc. are mentioned. A polyester film is preferred. Although it does not specifically limit as a polyester film, It is preferable that it is a polyester film which has the film formation property which has a dicarboxylic acid component and a diol component as main structural components.

  The main constituent dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethanedicarboxylic acid, Examples thereof include cyclohexane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, diphenyl ketone dicarboxylic acid, and phenylindane dicarboxylic acid. Examples of the diol component include ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) propane, bis ( 4-Hydroxyphenyl) sulfone, bisphenol fluorene hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like. Among the polyesters having these as main constituent components, from the viewpoint of transparency, mechanical strength, dimensional stability, etc., dicarboxylic acid components such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, diol components such as ethylene glycol and 1 Polyester having 1,4-cyclohexanedimethanol as the main constituent is preferred. Of these, polyesters mainly composed of polyethylene terephthalate and polyethylene naphthalate, 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 base film used in the present invention is preferably 10 to 300 μm, and more preferably 20 to 150 μm. In addition, the two base films may be stacked, and in this case, the type may be the same or different.

  Moreover, it is preferable that the transmittance | permeability of the visible region shown by JISR3106: 1998 is 85% or more, and, as for the base film which concerns on this invention, it is more preferable that it is 90% or more. If it is the range of such a transmittance | permeability, it will become advantageous for the transmittance | permeability of visible region shown by JISR3106: 1998 when it is set as an infrared shielding film to be 40% or more, and is preferable.

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

  As described above, the base film may be an unstretched film or a stretched film, but a stretched film is preferable from the viewpoint of improving the strength and suppressing thermal expansion.

  Moreover, the base film according to the present invention may be subjected to relaxation treatment or offline heat treatment in terms of dimensional stability. It is preferable that the relaxation treatment is performed in a process from the heat setting in the stretching process of the polyester film to the winding in the transversely stretched tenter or after exiting the tenter. The relaxation treatment is preferably performed at a treatment temperature of 80 to 200 ° C, more preferably 100 to 180 ° C. In addition, the relaxation rate is preferably 0.1 to 10% in both the longitudinal direction and the width direction, and more preferably, the relaxation rate is 2 to 6%. The base film subjected to the relaxation treatment is improved in heat resistance by the above-described offline heat treatment, and further has good dimensional stability.

In the base film according to the present invention, it is preferable to apply the undercoat layer coating solution inline on one side or both sides in the film forming process. In the present invention, undercoating during the film forming process is referred to as in-line undercoating. Examples of resins used in the undercoat layer coating solution useful in the present invention include polyester resins, acrylic-modified polyester resins, polyurethane resins, acrylic resins, vinyl resins, vinylidene chloride resins, polyethyleneimine vinylidene resins, polyethyleneimine resins, and polyvinyl alcohol resins. , Modified polyvinyl alcohol resin, gelatin and the like can be used, and these can be used alone or in combination of two or more. A conventionally well-known additive can also be added to these undercoat layers. The undercoat layer can be coated by a known method such as roll coating, gravure coating, knife coating, dip coating or spray coating. The coating amount of the undercoat layer is preferably about 0.01 to ² g / m ² (dry state).

[Infrared shield]
The infrared shielding film according to the present invention can be applied to a wide range of fields. For example, as a film for window pasting such as heat ray reflective film that gives heat ray reflection effect, film for agricultural greenhouses, etc. It is mainly used for the purpose of improving weather resistance. Moreover, it is used suitably also as an infrared shielding film for motor vehicles pinched | interposed between glass, such as laminated glass for motor vehicles. In this case, since the infrared shielding film can be sealed from outside air gas, it is preferable from the viewpoint of durability.

  In particular, the infrared shielding film according to the present invention is suitably used for a member that is bonded to a substrate such as glass or a glass-substituting resin directly or via an adhesive or an adhesive. A laminate of the infrared shielding film and the substrate is also called an infrared shielding body.

  Specific examples of the substrate include, for example, glass, polycarbonate resin, polysulfone resin, acrylic resin, polyolefin resin, polyether resin, polyester resin, polyamide resin, polysulfide resin, unsaturated polyester resin, epoxy resin, melamine resin, Examples thereof include phenol resin, diallyl phthalate resin, polyimide resin, urethane resin, polyvinyl acetate resin, polyvinyl alcohol resin, styrene resin, vinyl chloride resin, metal plate, ceramic and the like. The type of the resin may be any of a thermoplastic resin, a thermosetting resin, and an ionizing radiation curable resin, and these may be used alone or in combination of two or more. 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 (adhesive layer) for bonding the infrared shielding film and the substrate according to the present invention is preferably installed so that the infrared shielding film is 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.

  An adhesive (adhesive layer) may be used to bond the infrared shielding film according to the present invention and the substrate. As this adhesive, 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 adhesive because the peel strength can be easily controlled. When a solution polymerization polymer is used as the acrylic solvent adhesive, a known monomer 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 | system | group resin as said adhesion layer or an adhesion layer. Specific examples thereof include, for example, plastic polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., Mitsubishi Monsanto Kasei Co., Ltd.), ethylene-vinyl acetate copolymer (manufactured by DuPont, Takeda Pharmaceutical Co., Ltd., Duramin), Modified ethylene-vinyl acetate copolymer (manufactured by Tosoh Corporation, Mersen G). In the adhesive layer or the adhesive layer, an ultraviolet absorber, an antioxidant, an antistatic agent, a heat stabilizer, a lubricant, a filler, a colorant, an adhesion (adhesion) adjusting agent, and the like may be appropriately added and blended.

  Preferable substrates include plastic substrates, metal substrates, ceramic substrates, cloth substrates, etc., and the infrared shielding film of the present invention is applied to substrates of various forms such as film, plate, sphere, cube, and cuboid. Can be provided. Among these, a plate-shaped ceramic substrate is preferable, and an infrared shielding body in which the infrared shielding film of the present invention is provided on a glass plate is more preferable. As an example of a glass plate, the float plate glass described in JISR3202: 1996 and polished plate glass are mentioned, for example, As glass thickness, 0.01 mm-20 mm are preferable.

  As a method for providing the infrared shielding film of the present invention on the substrate, a method in which an adhesive layer is coated on the infrared shielding film as described above, and is attached to the substrate via the adhesive layer or the adhesive layer is suitably used. As a bonding method, dry bonding in which a film is directly bonded to a substrate, water bonding as described above, and the like can be applied, but in order to prevent air from entering between the substrate and the infrared shielding film. Moreover, it is more preferable to bond by the water sticking method from the viewpoint of ease of construction such as positioning of the infrared shielding film on the substrate.

  In addition, the infrared shielding body according to the present invention may be, for example, a form in which infrared shielding films are provided on both surfaces of glass, or an adhesive layer or an adhesive layer is coated on both surfaces of the infrared shielding film, thereby infrared shielding. A laminated glass-like form in which glass is bonded to both sides of the film may be used.

  Insulation performance and solar heat shielding performance of the infrared shielding film or infrared shield are generally JIS R3209: 1998 (multi-layer glass), JIS R3106: 1998 (transmittance, reflectance, emissivity, solar radiation of plate glass). Heat acquisition rate test method), JIS R3107: 1998 (a method for calculating the thermal resistance of sheet glass and the heat transmissivity of buildings).

  Measurements of solar transmittance, solar reflectance, emissivity, and visible light transmittance are as follows: (1) Using a spectrophotometer having a wavelength (300 to 2500 nm), the spectral transmittance and spectral reflectance of various single glass plates are measured. . 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, the solar reflectance, the solar absorption rate, and the modified emissivity are calculated according to JIS R3106: 1998 by calculating the solar transmittance, the solar reflectance, the solar absorption rate, and the vertical emissivity. The corrected emissivity is obtained by multiplying the coefficient shown in JIS R3107: 1998 by the vertical emissivity. The heat insulation and solar heat shielding properties are calculated by (1) calculating the thermal resistance of the multi-layer glass according to JIS R3209: 1998 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 R3107: 1998. (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 R3106: 1998 and subtracting from 1.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated still in detail, this invention is not limited to these Examples at all. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

(Examples 1-18, Comparative Examples 1-12)
<Production of infrared shielding film>
[Preparation of coating solution]
(Preparation of coating liquid L1 for low refractive index layer)
To 12 parts by mass of colloidal silica (Snowtex (registered trademark) OXS, manufactured by Nissan Chemical Industries, Ltd., solid content 10% by mass), polyvinyl alcohol (PVA-103, polymerization degree 300, saponification degree 98.5 mol%, Co., Ltd.) 2 parts by mass of a 5% by mass aqueous solution of Kuraray Co., Ltd. and 10 parts by mass of a 3% by mass aqueous boric acid solution were added, respectively, and the mixture was heated to 40 ° C. and stirred while polyvinyl alcohol (PVA-117, polymerization degree 1700, Ken 20 mass parts of 5 mass% aqueous solution of degree of conversion 98.5 mol%, manufactured by Kuraray Co., Ltd., and 1 mass part of 1 mass% aqueous solution of surfactant (Rapisol (registered trademark) A30, manufactured by NOF Corporation) were added. Then, 55 parts by mass of pure water was added to prepare a coating solution L1 for a low refractive index layer. However, the amount of pure water was adjusted so as to have the viscosity described in Table 1 below.

(Preparation of silica-attached titanium oxide sol)
After adding 2 parts by mass of pure water to 0.5 parts by mass of 15.0% by mass titanium oxide sol (SRD-W, volume average particle size 5 nm, rutile titanium oxide particles, manufactured by Sakai Chemical Industry Co., Ltd.), Heated. Next, 1.3 parts by mass of an aqueous silicic acid solution (sodium silicate 4 (manufactured by Nippon Chemical Industry Co., Ltd.) diluted with pure water so that the SiO ₂ concentration becomes 2.0 mass%) was gradually added. . Next, heat treatment was carried out at 175 ° C. for 18 hours in an autoclave, and after cooling, it was concentrated with an ultrafiltration membrane, thereby oxidizing (covering) SiO ₂ having a solid concentration of 20% by mass on the surface. A titanium sol (hereinafter, also simply referred to as “silica-attached titanium oxide sol”) was obtained.

(Preparation of coating liquid H1 for high refractive index layer)
5 mass of polyvinyl alcohol (PVA-103, polymerization degree 300, saponification degree 98.5 mol%, manufactured by Kuraray Co., Ltd.) is added to 30 parts by mass of the silica-attached titanium oxide sol (solid content 20.0 mass%) obtained above. 2 parts by weight of a 2% aqueous solution, 10 parts by weight of a 3% by weight aqueous boric acid solution and 10 parts by weight of a 2% by weight aqueous citric acid solution, respectively, and then heated to 40 ° C. with stirring, polyvinyl alcohol (PVA-617, polymerization degree) 1700, 20 mass parts of 5 mass% aqueous solution of saponification degree 95.0 mol%, manufactured by Kuraray Co., Ltd., and 1 mass part of 1 mass% aqueous solution of surfactant (Rapidol A30, manufactured by NOF Corporation) 27 parts by mass of water was added to prepare a coating solution H1 for a high refractive index layer. However, the amount of pure water was adjusted so as to have the viscosity described in Table 1 below.

[Production of infrared shielding film]
Using a slide hopper coating apparatus capable of 46-layer coating, a polyethylene terephthalate film having a thickness of 50 μm (manufactured by Toyobo Co., Ltd., while keeping the coating liquid L1 for the low refractive index layer and the coating liquid H1 for the high refractive index layer at 40 ° C. Cosmoshine (registered trademark) A4300, double-sided easy-adhesive layer) was applied alternately in total 8 to 46 layers simultaneously. At this time, the liquid supply tank is added so that the first layer (lowermost layer) and the second layer from the base film side are the low refractive index layers and the third and subsequent layers are alternately the lower refractive index layers. The coating solution was fed to the slide hopper coating device. When the flow rate was confirmed by a flow meter (FD-SS2A, manufactured by Keyence Corporation) provided between the liquid feeding tank and the slide hopper coating device, the flow rate fluctuation was not observed in the liquid feeding channel from the first layer to the top layer. It was confirmed that there was almost no (less than ± 1% with respect to the average flow rate). Thus, the infrared shielding film which a high refractive index layer and a low refractive index layer consist of a total of 8-46 layers was produced.

  In each Example and Comparative Example, the viscosity and coating amount of the low refractive index layer coating liquid L1 at 40 ° C., the viscosity and coating amount of the high refractive index layer coating liquid H1 at 40 ° C., and the lowermost layer, excluding the lowermost layer. Table 1 below shows the coating amount, the thickness per block (abbreviated as “block thickness” in Table 1), the number of coating layers in the simultaneous multilayer, and the coating speed. The viscosity of the coating solution was measured with a drop viscometer. In each example and comparative example, the slide surface angle was 10 °, and the viscosity of the lowermost coating solution was 10 mPa · s.

[Evaluation of infrared shielding film]
About the infrared shielding film manufactured in Examples 1-18 and Comparative Examples 1-12, the color unevenness of the width direction of a base film by visual observation, a stripe failure, a grain-like unevenness, and the following performance evaluation were performed. In this specification, the color unevenness in the width direction means the presence or absence of color unevenness in the width direction when the infrared shielding film is viewed with reflected light, and the streak failure is manufactured by simultaneous multilayer coating. It means a state in which streaky coating unevenness has occurred on the surface of the infrared shielding film, and the grain-like unevenness means unevenness caused by the ripples on the slide surface.

(Visual evaluation of uneven color, streak failure, and grainy unevenness)
○: Not generated Δ: Slightly generated ×: Strongly generated.

  In addition, the infrared shielding film manufactured by the manufacturing method of the present invention does not generate strongly ("x") as a result of visual evaluation of color unevenness in the width direction, streak failure, and wood-like unevenness. Although it is necessary and may occur slightly (“Δ”), it is particularly preferable that all are not generated (“◯”).

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

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

  In addition, the infrared shielding film manufactured by the manufacturing method of the present invention must not be 5% or more (“×”) as a result of the film thickness variation rate, and is 3% or more and less than 5% (“ Δ ”), but less than 3% (“ ◯ ”) is particularly preferred.

(Measurement of color difference)
Using a spectrophotometer (integral sphere, manufactured by Hitachi, Ltd., U-4000 type), the back surface on the measurement side of the manufactured infrared shielding film is roughened and then light-absorbed with a black spray. The reflection of light on the back surface was prevented. Next, the reflectance in the visible light region (360 nm to 740 nm) was measured under conditions of 5 ° regular reflection and 45 ° regular reflection. From the obtained results, the L ^* a ^* b ^* value was calculated, and the color difference ΔE between the 5 ° specular reflection condition and the 45 ° specular reflection condition was determined by the following equation 2.

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

  In addition, the infrared shielding film manufactured by the manufacturing method of the present invention must not be 20 or more (“x”) as a result of the color difference, and is 10 or more and less than 20 (“Δ”). However, it is particularly preferably less than 10 (“◯”).

  The evaluation results of the film thickness fluctuation rate and the color difference are shown in Table 2 below.

  As is clear from the results in Table 2, the infrared shielding films of Examples 1 to 18 had good results with respect to color unevenness, streak failure, grainy unevenness, film thickness variation rate, and color difference. That is, the coating solution having a viscosity at 40 ° C. of 5 to 200 mPa · s is applied simultaneously with a slide hopper type coating device having a thickness of 25 to 50 mm per block, so that the uniformity in the width direction is high. In addition, it is possible to obtain an infrared shielding film with suppressed color unevenness in the width direction, streak failure, and grain-like unevenness, good rate of film thickness variation, no color difference, and good appearance.

  This application is based on Japanese Patent Application No. 2013-104059 filed on May 16, 2013, the disclosure of which is incorporated by reference in its entirety.

Claims (5)

  A step of simultaneously applying 10 to 40 layers of a coating solution for a high refractive index layer and a coating solution for a low refractive index layer on a continuously running substrate film using a slide hopper type coating device. The high-refractive-index layer coating solution and the low-refractive-index layer coating solution have a viscosity at 40 ° C. of 5 to 200 mPa · s, and the slide hopper type coating device The manufacturing method of the infrared shielding film whose thickness per block of is 25-50 mm.   The manufacturing method of Claim 1 whose thickness per block of the said slide hopper type coating device is 30-50 mm. The manufacturing method according to claim 1 or 2, wherein a coating amount of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer, excluding the lowermost layer, is ² to 5 g / m2. The manufacturing method of any one of Claims 1-3 whose application amount of the coating liquid for the high refractive index layer or the coating liquid for the low refractive index layer in the lowermost layer is 10 to 40 g / m ² .   The manufacturing method of any one of Claims 1-4 whose coating speed is 60-200 m / min.