WO2014185384A1

WO2014185384A1 - Production method for infrared shielding film

Info

Publication number: WO2014185384A1
Application number: PCT/JP2014/062626
Authority: WO
Inventors: 和彦坂田; 篤志齋藤
Original assignee: コニカミノルタ株式会社
Priority date: 2013-05-16
Filing date: 2014-05-12
Publication date: 2014-11-20
Also published as: CN105228755A; JP6406248B2; JPWO2014185384A1

Abstract

The purpose of the present invention is to provide a production method for an infrared shielding film that has a satisfactory appearance and in which irregularities in a coating surface rarely occur or do not occur at all. The present invention is a production method for an infrared shielding film that includes a step in which 10-40 layers of a coating solution for a high refractive index layer and a coating solution for a low refractive index layer are simultaneously applied in a layered manner on a continuously moving substrate film using a slide hopper coating device. The viscosities of the coating solution for a low refractive index layer and the coating solution for a high refractive index layer at 40 °C are 5-200 mPa·s. The angle of the slide surface of the slide hopper coating device with respect to the horizontal plane is 2-15°. The thickness per block of the slide hopper coating device is 15-40 mm.

Description

Infrared shielding film manufacturing method

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

Conventionally, multilayer laminated films such as antireflection films, infrared reflection films, and color light-sensitive materials 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 manufacturing a multilayer laminated film as described above as a wet film forming apparatus capable of simultaneously applying a plurality of coating liquids. However, a manufacturing method for reducing coating unevenness is required. .

In JP-A-03-219237 (US Pat. No. 5,656,417), a coating solution having a viscosity of 15 cP to 100 cP is used for forming the lowermost layer, and seven or more layers are coated on the lowermost layer. A method for producing a color light-sensitive material is disclosed, in which the viscosity of the solution is 30 cP or more and the coating is adjusted so that the arithmetic average of the viscosity of the coating solution of 7 layers or more is 60 to 300 cP. According to this manufacturing method, it is possible to obtain a uniform coated surface that is stable at high speed and does not cause color unevenness.

However, in the technique described in the above Japanese Patent Application Laid-Open No. 03-219237 (US Pat. No. 5,656,417), since the coating solution is highly viscous, agglomerates are easily generated, and it is difficult to defoam the coating solution. Therefore, when this coating solution is applied, a foam failure or a foreign matter failure due to agglomerates occurs, which is still insufficient for improving the appearance of the resulting product. In addition, since the coating liquid used for manufacturing the infrared shielding film uses both a low-viscosity liquid and a high-viscosity liquid, ripples occur on the slide surface during multi-layer coating, and the coated product has a grain shape. There has been a problem of causing uneven coating of the film.

Accordingly, the present invention aims to provide a method for producing an infrared shielding film having a good appearance with little or no occurrence of grainy unevenness, streak failure, bubble / foreign matter failure on the coated surface. To do.

The present inventors have intensively studied 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 angle of the slide surface of the slide hopper type applicator with respect to the horizontal plane and the thickness per block of the slide hopper type applicator to a specific range. It was. 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 a multilayer coating, wherein 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, An infrared shielding film manufacturing method, wherein an angle of the slide surface of the slide hopper type coating device with respect to a horizontal plane is 2 to 15 °, and a thickness per block of the slide hopper type coating device is 15 to 40 mm. .

It is the schematic which shows an example of a slide hopper type coating device. In FIG. 1, 1 is a base film, 2 is a back roll, 3 is a coater die, 4 is a coating solution, 5 is a vacuum chamber, 6 is a wetted part, and 7 is a back. The angle (γ) between the roll center and the wetted part, 8 is the angle (β) with respect to the horizontal surface of the slide surface, and 9 is the angle (α) between the running surface of the base film and the slide surface. 10 is a decompression part, 11 is a block, t is the thickness of a block. It is a schematic diagram which shows the mechanism which suppresses the ripple of the coating liquid on a slide surface. In FIG. 2, A is the upper liquid and B is the lower liquid.

Hereinafter, the method for producing the infrared shielding film of the present invention will be described 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 11 (in FIG. 1, a four-layer simultaneous multi-layer coating mode is shown), and the coating liquid 4 flows down thereon. 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 angle 8 (β) with respect to the horizontal plane of the slide surface shown in FIG. 1 is set to 2 to 15 °, and the thickness per block (t in FIG. 1) is set to 15 to 40 mm. As a result, the ripples of the coating liquid on the slide surface can be suppressed, and there is no grainy unevenness on the coating surface, no streak failure, bubble / foreign matter failure occurs, and an infrared having a good appearance. A shielding film can be obtained.

FIG. 2 is a schematic diagram showing a mechanism for suppressing the ripple of the coating liquid on the slide surface. FIG. 2A shows the coating liquid when the angle of the slide surface with respect to the horizontal plane is large, that is, when the angle exceeds 15 °. The state of is shown. (B) shows the production method of the present invention, and shows the state of the coating liquid when the angle of the slide surface with respect to the horizontal plane is 2 to 15 °. As shown in FIG. 2A, when the angle of the slide surface with respect to the horizontal plane exceeds 15 °, the upper layer liquid A flowing from above the slide surface is thin, so that the lower layer liquid B flows out from the slide surface. The coating liquid undulates due to the impact at the time. When such a coating solution is applied, a grain-like disorder occurs on the coated surface.

On the other hand, as shown in FIG. 2B, when the angle of the slide surface with respect to the horizontal plane is smaller than 15 °, since the upper layer liquid A flowing from above the slide surface is thick, the lower layer liquid B is removed from the slide surface. There is little or no wave of the coating liquid due to the impact when it flows out. Therefore, even if such a coating solution is applied, an unevenness of wood grain does not occur on the coated surface, and an infrared shielding film having an excellent appearance can be obtained.

However, even in the form of (b) in FIG. 2, when the thickness per block is thick, the distance that the coating solution flows down the slide surface becomes long, and the coating solution undulates at the downstream portion of the slide surface. . On the other hand, in the present invention, by setting the thickness per block to 15 to 40 mm, a coating solution that hardly generates undulations or does not occur at all even when multi-layer simultaneous multi-layer coating such as 40 layers is performed. An infrared shielding film excellent in appearance can be obtained with almost no grainy unevenness on the coated surface.

Note that the above mechanism is based on speculation, and the present invention is not limited to the above mechanism.

[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 for 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 alkali region of the titanate cake), JP 2000-204301 A (A sol in which a rutile-type 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 R1 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, such as 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 alkaline 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.

Generally, 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. In the infrared shielding film of the present embodiment, the preferred refractive index of the low refractive index layer is 1.10 to 1.60, more preferably 1.30 to 1.50. The preferable refractive index of the high refractive index layer is 1.80 to 2.50, more preferably 1.90 to 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 model (manufactured by Hitachi, Ltd.) as a spectrophotometer, the back side of the measurement side of each sample was roughened, and then light absorption treatment was performed with a black spray, so that 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, an average value is obtained, and the average refractive index is obtained from the measurement result.

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 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 34 or less, more preferably 10 or more and 25 or less, and further 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. Further, the thickness per layer of the low refractive index layer excluding the lowermost layer is preferably 20 to 500 nm, and more preferably 50 to 300 nm. On the other hand, the thickness per layer of the high refractive index layer excluding the lowermost 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, more preferably 400 to 1200 nm, regardless of whether the lowermost layer is a low refractive index layer or a high refractive index layer.

Furthermore, as an optical characteristic of the infrared shielding film according to the present invention, the transmittance in the visible light region represented by JIS R3106: 1998 is preferably 50% or more, more preferably 75% or more, and further 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) ), And may have one or more functional layers such as an interlayer film used for laminated glass.

[Infrared shielding film manufacturing method]
The coating liquid used in the present invention is applied by simultaneous multi-layer coating using a slide hopper type coating apparatus, and a high refractive index coating liquid and a low refractive index coating liquid are laminated on a slide surface to form a base material. By applying to a film, a high refractive index layer and a low refractive index layer are formed.

(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 ease of operation, the solvent for the coating solution is particularly preferably water or a mixed solvent of water and methanol, ethanol, or ethyl acetate.

The second metal oxide particles used in the coating solution for the high refractive index layer are preferably prepared separately in a dispersion state before preparing the coating solution. 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, even if the angle of the slide surface with respect to the horizontal plane is 2 to 15 °, ripples are generated on the slide surface, resulting in grainy unevenness. On the other hand, when it exceeds 200 mPa · s, there is almost no occurrence of grainy unevenness, but since defoaming becomes difficult, foam failure and foreign matter failure due to aggregates are observed. The viscosity is a value measured with a Brookfield viscometer.

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. Further, the concentration of the first metal oxide particles in the coating solution for the low refractive index layer is preferably 1 to 60% by 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. The concentration of the second metal oxide particles in the coating solution for the high refractive index layer is preferably 1 to 60% by 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 still more 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.

The 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 not particularly limited, but is preferably 1 to 10 g / m ² , and preferably 2 to 5 g / m ^2. more preferably m ^2. If it is this range, the effect of this invention will be acquired more efficiently. Lowermost coating weight is preferably 5 ~ 45g / ^{m 2,} more preferably 10 ~ 40g / ^{m 2.}

Furthermore, as described above, in the manufacturing method of the present invention, the angle of the slide surface of the slide hopper type coating apparatus with respect to the horizontal plane is 2 to 15 °. If the angle is less than 2 °, the flow velocity on the slide surface is slowed down, causing a streak failure due to a decrease in the dynamic pressure on the slide surface. On the other hand, when the angle exceeds 15 °, undulations occur on the slide surface, and a wood-like coating unevenness occurs. The angle is preferably 5 to 10 °.

Also, the thickness per block of the slide hopper type coating device is 15 to 40 mm. When the thickness is less than 15 mm, the block is deformed, and the flow rate uniformity in the width direction of the base film is deteriorated. On the other hand, when the thickness exceeds 40 mm, the distance that the coating liquid flows down the slide surface becomes long. The undulation of the coating liquid is generated on the top, and wood-like coating unevenness occurs. The thickness is preferably 15 to 30 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 solution for the high refractive index layer and the coating solution for the low refractive index layer are heated to 30 to 60 ° C., and then the coating solution for the high refractive index layer and the coating solution 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) preferably to 1 to 15 ° C. and then dried at 10 ° C. or higher. More preferable drying conditions are a wet bulb temperature of −10 to 50 ° C. and a film surface temperature of 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 preferable thickness at the time of drying as shown above.

As the 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 rate-decreasing 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 until the setting is completed 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 acid ester copolymer or acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer 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-based copolymers such as vinyl acetate-acrylic acid copolymers and their salts Natural water-soluble polymers such as gelatin and thickening polysaccharides. Among these, particularly preferable examples include polyvinyl alcohols, polyvinylpyrrolidones, and copolymers containing them, polyvinyl butyral, gelatin, thickening polysaccharides from the viewpoint of handling during production and flexibility of the film. (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 hydrolysis of 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, 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 in the main chain or side chain of the polyvinyl alcohol as described in, for example, JP-A-61-110483. 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, And 1-dimethyl-3-dimethylaminopropyl) acrylamide. The ratio of the cation-modified group-containing monomer in 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 is added to a part of vinyl alcohol as described in JP-A-7-9758, 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 curing agents (formaldehyde, glycoxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy-1, 3,5-s-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum 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 as a single aqueous solution or as a mixture of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax.

An aqueous solution of boric acid and borax can be added only in a relatively dilute aqueous solution, but a thick aqueous solution can be obtained by mixing both, 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 near-infrared shielding characteristics are achieved. Especially when using a set coating process in which a multi-layered multilayer 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 film surface is dried. In this case, the effect can be expressed more preferably.

The total amount of the curing agent used is preferably 1 to 600 mg per 1 g of polyvinyl alcohol, 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-61-146591, 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 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 components, from the viewpoints of transparency, mechanical strength, dimensional stability, etc., dicarboxylic acid components such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, diol components such as ethylene glycol and 1 Polyester having 1,4-cyclohexanedimethanol as the main constituent is preferred. Among these, polyesters mainly composed of polyethylene terephthalate and polyethylene naphthalate, copolymerized polyesters composed of terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, and mixtures of two or more of these polyesters are mainly used. Polyester as a constituent component is preferable.

The thickness of the base film used in the present invention is preferably 10 to 300 μm, 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.

The base film according to the present invention preferably has a visible light region transmittance of 85% or more, more preferably 90% or more, as shown in JIS R3106: 1998. If it is the range of such a transmittance | permeability, it will become advantageous for the transmittance | permeability of the visible region shown by JISR3106: 1998 when it is set as an infrared shielding film to be 40% or more, and is preferable.

The base 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 a 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 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 in the range of 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 to be 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.

In order to bond the infrared shielding film according to the present invention and the substrate, an adhesive (adhesive layer) may be used. 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.

Further, a polyvinyl butyral resin or an ethylene-vinyl acetate copolymer resin used as an intermediate layer of laminated glass may be used as the above-mentioned adhesive layer or adhesive layer. Specific examples thereof include, for example, plastic polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., Mitsubishi Monsanto Kasei Co., Ltd., etc.), ethylene-vinyl acetate copolymer (manufactured by DuPont, manufactured by Takeda Pharmaceutical Co., Ltd., duramin), Modified ethylene-vinyl acetate copolymer (Mersen (registered trademark) G, manufactured by Tosoh Corporation), and the like. 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. Examples of the glass plate include float plate glass and polished plate glass described in JIS R3202: 1996, and the glass thickness is preferably 0.01 mm to 20 mm.

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.

The heat 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 (heat resistance of plate glass and calculation method of heat transmissivity in architecture).

Measurements of solar transmittance, solar reflectance, emissivity, and visible light transmittance are as follows: (1) Using a spectrophotometer with a wavelength (300-2500 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 corrected emissivity are calculated according to JIS R3106: 1998 by calculating the solar transmittance, solar reflectance, solar absorption rate, and vertical emissivity. The corrected emissivity is obtained by multiplying the coefficient shown in JIS R3107: 1998 by the vertical emissivity. The heat insulation and solar heat shielding properties are calculated by (1) calculating the thermal resistance of the multilayer glass according to JIS 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) The solar heat shielding property is calculated by calculating the solar heat acquisition rate according to JIS R3106: 1998 and subtracting it from 1.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

(Examples 1 to 18, Comparative Examples 1 to 14)
<Production of infrared shielding film>
[Preparation of coating solution]
(Preparation of coating liquid L1 for low refractive index layer)
Colloidal silica (Snowtex (registered trademark) OXS, manufactured by Nissan Chemical Industries, Ltd., solid content 10% by mass) in 12 parts by mass, polyvinyl alcohol (PVA-103, polymerization degree 300, saponification degree 98.5 mol%, Co., Ltd.) 2 parts by weight of a 5% by weight aqueous solution of Kuraray Co., Ltd. and 10 parts by weight of a 3% by weight aqueous boric acid solution were added, and the mixture was then 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 type 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 parts by mass of polyvinyl alcohol (PVA-103, polymerization degree 300, saponification degree 98.5 mol%, manufactured by Kuraray Co., Ltd.) was added to 30 parts by mass of the silica-attached titanium oxide sol (solid content 20.0% by 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 were added, and the mixture was heated to 40 ° C. with stirring and 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 type coating apparatus capable of coating 46 layers, 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. , Cosmo Shine (registered trademark) A4300, double-sided easy-adhesion layer) were alternately applied in a total of 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 are the low refractive index layer and the third and subsequent layers are alternately the lower refractive index layer from the base film side. The coating solution was fed to a slide hopper type coating device. When the flow rate was confirmed by a flow meter (FD-SS2A, manufactured by Keyence Corporation) provided between the liquid feed tank and the slide hopper type coating device, the flow rate varied in the liquid feed channel from the first layer to the top layer. It was confirmed that there was almost no (less than ± 1% of the average flow rate). In this way, an infrared shielding film having a total of 8 to 46 low refractive index layers and high refractive index layers was produced.

In each example and comparative example, the viscosity and coating amount of the coating solution L1 for the low refractive index layer, the viscosity and coating amount of the coating solution H1 for the high refractive index layer, the coating amount of the bottom layer coating solution, and the slide, excluding the bottom layer Table 1 below shows the angle of the surface with respect to the horizontal plane, the thickness per block, 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. Furthermore, in each Example and Comparative Example, all the blocks having the same thickness shown in Table 1 were used. For example, in Example 1, it shows that only the 20-mm-thick block was used.

[Evaluation of infrared shielding film]
The infrared shielding films produced in Examples 1 to 18 and Comparative Examples 1 to 14 were subjected to visual grain-like unevenness, streak failure, bubble / foreign material failure, and the following performance evaluation. The evaluation results are shown in Table 2 below.

(Visual evaluation of grain-like unevenness, streak failure, foam / foreign material failure)
○: Not generated Δ: Slightly generated ×: Strongly generated.

In addition, the infrared shielding film manufactured by the manufacturing method of the present invention must not generate any strong ("x") as a result of visual evaluation of streak failure, grainy unevenness, and bubble / foreign material failure. It may be slightly generated (“Δ”), but 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 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 (using an integrating sphere, manufactured by Hitachi, Ltd., U-4000 type), the back side 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 gave good results with respect to grainy unevenness, streak failure, bubble / foreign material failure, film thickness variation rate, and color difference. That is, a coating solution having a viscosity in the range of 5 to 200 mPa · s at 40 ° C. is a slide hopper type coating in which the angle of the slide surface with respect to the horizontal plane is 2 to 15 ° and the thickness per block is 15 to 40 mm. By applying simultaneous multilayer coating with an apparatus, it is possible to obtain an infrared shielding film that suppresses unevenness due to undulations, has a good thickness fluctuation rate, has no color difference, and has a good appearance.

This application is based on Japanese Patent Application No. 2013-104052 filed on May 16, 2013, the disclosure of which is incorporated by reference in its entirety.

Claims

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 coating device. A method for producing an infrared shielding film comprising:
The viscosity at 40 ° C. of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is 5 to 200 mPa · s,
An angle of the slide surface of the slide hopper type coating device with respect to a horizontal plane is 2 to 15 °,
A method for producing an infrared shielding film, wherein a thickness per block of the slide hopper type coating apparatus is 15 to 40 mm.
The manufacturing method according to claim 1, wherein the number of layers to be applied simultaneously is 10 or more and 34 or less.
The production method according to claim 1 or 2, wherein the 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 / m 2 .
The production method according to any one of claims 1 to 3, wherein a coating amount of the coating solution for the high refractive index layer or the coating solution for the low refractive index layer in the lowermost layer is 10 to 40 g / m 2 .
The production method according to any one of claims 1 to 4, wherein the coating speed is 60 to 200 m / min.