JP6589447B2 - Manufacturing method of optical reflection film - Google Patents

Description

  The present invention relates to a method for producing an optical reflection film that performs simultaneous multilayer coating using a slide hopper coating apparatus.

  Conventionally, multilayer laminated films such as an antireflection film, an infrared reflection film, and a color photosensitive material are manufactured by dry film formation or wet film formation. In terms of productivity, wet film formation performed by applying and drying a coating solution is superior to dry film formation such as chemical vapor deposition (CVD) and physical vapor deposition (PVD).

  The slide hopper coating apparatus is suitably used for manufacturing a multilayer laminated film such as an optical reflection film as a wet film forming apparatus capable of simultaneously coating a plurality of coating liquids. However, in the production of a multilayer laminated film using a slide hopper coating apparatus, coating unevenness occurs during simultaneous multilayer coating, and a method for reducing this coating unevenness is required.

  For example, a coating solution having a viscosity of 15 cP to 100 cP is used for forming the lowermost layer, the viscosity of the coating solution used for forming seven or more layers on the lowermost layer is set to 30 cP or more, and the coating solution for forming these seven or more layers is used. A method for producing a color photographic material in which the arithmetic average of viscosity is adjusted to 60 to 300 cP is disclosed (for example, see Patent Document 1). According to this manufacturing method, it is described that it is possible to obtain a uniform application state that does not cause color unevenness stably at high speed.

Japanese Patent Laid-Open No. 03-219237

  However, in the production of an optical reflection film, a low viscosity liquid and a high viscosity liquid having a very large viscosity difference are used, and these are alternately laminated to perform simultaneous multilayer coating. When using a slide hopper applicator and laminating liquids with such a large viscosity difference alternately and performing simultaneous multi-layer coating, ripples occur on the slide surface, and the coated product has a grainy coating unevenness. (Hereinafter also referred to as wood grain unevenness) occurs.

  In order to solve the above-described problems, the present invention provides a method for producing an optical reflective film with improved grain-like unevenness.

  In the method for producing an optical reflective film of the present invention, a coating solution for a high refractive index layer and a coating solution for a low refractive index layer are formed on a continuously running substrate film by using a slide hopper coating apparatus. And a step of simultaneously applying the following layers. When the shear velocity on the high-viscosity liquid side of the velocity component parallel to the slide surface of the falling liquid film on the slide surface at each interface on each block is d and the flow time of each block at the interface is t, The simultaneous multi-layer coating is performed under the condition that Σ (d × t) ≦ 50 is the maximum integrated value from the formation of the interface (d × t) in FIG.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical reflection film which improved the grain-like nonuniformity can be provided.

It is a schematic diagram of the milder of an example of a dispersing device. It is the schematic which shows an example of a slide hopper coating device. It is a figure which shows the mode of the simultaneous multilayer flow on the slide surface in a slide hopper coating device. It is a figure which shows the relationship between the shear rate (d) on a slide surface, and a slide surface film thickness (y) in the system by which the high-viscosity liquid and the low-viscosity liquid were laminated | stacked alternately.

Hereinafter, although the example of the form for implementing this invention is demonstrated, this invention is not limited to the following examples.
The description will be given in the following order.
1. 1. Outline of optical reflection film Manufacturing method of optical reflection film

<1. Overview of optical reflective film>
Prior to the description of the embodiment of the method for producing an optical reflecting film, an outline of the optical reflecting film produced by the method for producing an optical reflecting film will be described.

[Optical reflection film]
The optical reflective film manufactured by the above manufacturing method has a configuration in which a laminate including a high refractive index layer and a low refractive index layer is disposed on a substrate. The optical reflective film having such a configuration can reflect a light beam having a specific wavelength by providing a laminate in which the optical film thickness (film thickness × refractive index) of the high refractive index layer and the low refractive index layer is appropriately controlled. it can. For example, when reflecting a light beam having a wavelength of 200 to 400 nm (ultraviolet light), it becomes an ultraviolet shielding film, and when reflecting a light beam having a wavelength of 400 to 700 nm (visible light), it becomes a visible light colored film, and a light beam having a wavelength of 700 to 1200 nm. When reflecting (infrared rays), it becomes an infrared shielding film. Further, by appropriately designing the optical film thickness of the laminate, the wavelength and reflectance of the reflected light beam can be controlled to obtain a metallic glossy film. Among these, the light ray that can be shielded by the optical reflection film is preferably a light ray having a wavelength of 200 nm to 1000 μm in the ultraviolet to infrared region, more preferably a light ray having a wavelength of 250 to 2500 nm, and a wavelength of 700 to 1200 nm. The light in the near infrared region is more preferable.

  In the following description, the configuration of an infrared shielding film will be described as a representative example of the optical reflection film. In addition, as a structure of an optical reflection film, it is not restricted to an infrared shielding film, It can also be set as another structure.

[Infrared shielding film]
The structure of an infrared shielding film has a base film and one or more units (laminated body) comprised from a high refractive index layer and a low refractive index layer. Moreover, it is preferable to have the form of the alternating laminated body by which the high refractive index layer and the low refractive index layer were laminated | stacked alternately. The infrared shielding film may be provided with a plurality of units (laminates) composed of a high refractive index layer and a low refractive index layer.

  In addition, the high refractive index layer in the laminate is a layer having a higher refractive index than other layers to be compared, and the low refractive index layer has a lower refractive index than other layers to be compared. It is a structure which is called from the relationship of the relative refractive index in each layer. For this reason, the names of these structures are replaced as needed depending on the structure of the laminate and the refractive index relationship with the layer to be compared.

  Further, in a unit composed of a high refractive index layer and a low refractive index layer, 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”) and the metal oxide particles contained in the high refractive index layer (hereinafter referred to as “second metal oxide particles”) And a layer containing the first metal oxide particles and the second metal oxide particles may be formed. In this 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).

As the high refractive index layer and a low refractive index layer metal oxide particles used in, but not limited to, 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), etc. Can be mentioned. Of these, silicon oxide (SiO ₂ ) is used as the first metal oxide particles contained in the coating solution for the low refractive index layer, and titanium oxide is used as the second metal oxide particles contained in the coating solution for the high refractive index layer. (TiO ₂ ) is preferably used for each. As the silicon oxide, colloidal silica is preferable, and as the titanium oxide, a silica-attached titanium oxide sol described later is preferable.

  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. When the coating amount is 30% by mass or less, a desired refractive index of the high refractive index layer is obtained, and when the coating amount is 3% or more, particles can be stably formed.

As a method of coating the 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 hydrated oxide treatment of rutile titanium oxide; hydrous oxide of silicon and / or aluminum on the surface of titanium oxide after peptization in the alkali region of titanate cake Of titanium oxide sol by which the surface treatment is performed by precipitating the material), JP-A-2000-204301 (sol in which rutile-type titanium oxide is coated with a composite oxide of Si and Zr and / or Al, hydrothermal treatment) JP 2007-246351 (complexing action to a hydrosol of titanium oxide obtained by peptizing hydrous titanium oxide with respect to organoalkoxysilane or titanium oxide of formula R ¹ _n SiX _4-n as a stabilizer. By adding a compound containing, adding to a solution of sodium silicate or silica sol in the alkaline region, adjusting pH, and aging, Reference can be made to the matters described in the method for producing a titanium oxide hydrosol coated with hydroxide.

  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, 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 or more. Is more preferably 0.3 or more, still more preferably 0.35 or more, and particularly preferably 0.4 or more. When the infrared shielding film has a plurality of units of the high refractive index layer and the 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 an infrared shielding film, 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 optical reflection film, the refractive indexes of the high refractive index layer and the low refractive index layer can be determined according to the following method.
First, a sample in which each refractive index layer for measuring a refractive index is coated as a single layer on a base film is prepared, and this sample is cut into 10 cm × 10 cm. And after roughening the back surface of the measurement side of each sample, light absorption processing is performed with a black spray to prevent reflection of light on the back surface. Then, using a spectrophotometer U-4000 type (manufactured by Hitachi, Ltd.), the average refraction from the average value obtained by measuring the reflectance in the visible light region (400 nm to 700 nm) at 25 points under the condition of regular reflection at 5 degrees. Find the rate.

  The reflectance in the specific wavelength region is determined by the difference in refractive index between two adjacent layers and the number of stacked layers, and the larger the difference in refractive index, the same reflectance can be obtained with a smaller number of layers. The refractive index difference and the required number of layers can be calculated using commercially available optical design software. For example, in order to obtain an infrared reflectance of 90% or more, if the refractive index difference is smaller than 0.1, it is necessary to stack 200 layers or more. When such a number of layers is required, not only the productivity is lowered, but also scattering at the laminated interface is increased, the transparency is lowered, and it is very difficult to manufacture without failure. From the viewpoint of improving the reflectivity and reducing the number of layers, the upper limit value of the difference in refractive index between two adjacent layers is not limited, but is practically about 1.4.

  The number of layers constituting the laminate of the infrared shielding film is 10 to 40 layers, preferably 10 to 34 layers, and more preferably 10 to 26 layers. Further, in the infrared shielding film, the outermost layer and the lowermost layer of the laminate may be a layer composed of either a high refractive index layer or a low refractive index layer. As the infrared shielding film, the lowermost layer of the laminate adjacent to the base film is preferably a low refractive index layer, and the outermost layer is also preferably a low refractive index layer.

  The total thickness of the infrared shielding film is preferably 12 to 315 μm, more preferably 15 to 200 μm, and still more preferably 20 to 150 μm. Moreover, it is preferable that the film thickness after drying per layer of the low-refractive-index layer except a lowermost layer is 30-500 nm, and it is more preferable that it is 30-300 nm. On the other hand, the film thickness after drying per layer of the high refractive index layer excluding the lowermost layer is preferably 30 to 500 nm, and more preferably 30 to 300 nm. The film thickness after drying 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.

  As the optical characteristics of the infrared shielding film, 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. It is preferable to have a region having a reflectance exceeding 50% in a region of 900 to 1400 nm.

  In addition, the infrared shielding film has a conductive layer, an antistatic layer, a gas barrier layer, an easy adhesion layer (adhesive layer), an antifouling layer, a deodorizing layer, a droplet layer, and an easy slip layer for the purpose of adding further functions. , Hard coat layer, abrasion 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, high refractive index layer And one or more of functional layers such as an interlayer film layer used for laminated glass, an infrared cut layer (metal layer, liquid crystal layer), a colored layer (visible light absorption layer), and a low refractive index layer. Good. These layers can be provided on the main surface of the base film on the side where the laminate is not formed or on the outermost surface layer of the laminate.

(Base film)
Various resin films can be used as the base film of the infrared shielding film. Examples of the base film include polyolefin films (such as polyethylene and polypropylene), polyester films (such as polyethylene terephthalate and polyethylene naphthalate), polyvinyl chloride, and cellulose acetate. The base film is preferably a polyester film. Although it does not specifically limit as a polyester film, It is preferable that it is a polyester film which can mainly form a dicarboxylic acid component and a diol component, and can form a film.

  The dicarboxylic acid component which is the main component of the polyester film includes terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl Examples include ethanedicarboxylic acid, cyclohexanedicarboxylic acid, diphenyldicarboxylic acid, diphenylthioether dicarboxylic acid, diphenylketone dicarboxylic acid, and phenylindanedicarboxylic 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 viewpoint of transparency, mechanical strength, dimensional stability, etc., as dicarboxylic acid components, terephthalic acid and 2,6-naphthalenedicarboxylic acid, diol components as ethylene glycol and 1, Polyester having 4-cyclohexanedimethanol as a 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 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 types of materials to be stacked 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 a base film, it is more preferable that it is 90% or more. Within such a transmittance range, it is advantageous to make the transmittance in the visible light region shown in JIS R3106: 1998 when the infrared shielding film is used to be 40% or more.

  The base film 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. In addition, the unstretched base film is made by using a known method such as uniaxial stretching, tenter sequential biaxial stretching, tenter simultaneous biaxial stretching, or tubular simultaneous biaxial stretching. A stretched film can be produced by stretching in the (vertical axis) direction or in the direction perpendicular to the flow direction of the base film (horizontal axis). The draw ratio in this case can be appropriately selected according to the resin as the raw material for the base film, but is preferably 2 to 10 times in the vertical axis direction and the horizontal axis direction, respectively. The base film may be an unstretched film or a stretched film, but a stretched film is preferred from the viewpoints of improving the strength and suppressing thermal expansion.

  Further, the base film may be subjected to relaxation treatment or off-line heat treatment in terms of dimensional stability. The relaxation treatment is preferably performed in the transversely stretched tenter or after the tenter is taken out until the winding step after the heat setting in the stretched film forming process of the polyester film. The relaxation treatment is preferably performed at a treatment temperature of 80 to 200 ° C, more preferably 100 to 180 ° C. Moreover, it is preferable that the relaxation rate is in the range of 0.1 to 10% in both the longitudinal direction and the width direction, and more preferably in the range of 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.

The base film is preferably coated with the undercoat layer coating solution in-line on one or both sides during the film formation process. The undercoating during the film forming process is called inline undercoating. The resin used for the undercoat layer coating solution is polyester resin, acrylic modified polyester resin, polyurethane resin, acrylic resin, vinyl resin, vinylidene chloride resin, polyethyleneimine vinylidene resin, polyethyleneimine resin, polyvinyl alcohol resin, modified polyvinyl alcohol resin. Or gelatin. These resins can be used alone or in combination of two or more. A conventionally well-known additive can also be added to an undercoat layer. 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).

<2. Manufacturing method of optical reflection film>
Next, the manufacturing method of an optical reflection film is demonstrated. In the method for producing an optical reflection film, a layer composed of a high refractive index layer and a low refractive index layer is formed by a simultaneous multilayer coating process (simultaneous multilayer coating process) of 10 to 40 layers using a slide hopper coating apparatus. Create a body. In the production of this laminate, the high refractive index coating liquid and the low refractive index coating liquid are laminated on the slide surface of the slide hopper coating apparatus. And the high refractive index layer and the low refractive index layer are formed on a base film by apply | coating this laminated | stacked coating liquid for high refractive index and the coating liquid for low refractive index to a base film.

Moreover, in manufacture of an optical reflection film, the above-mentioned simultaneous multilayer coating is performed on the conditions shown below.
First, on the slide surface on each block constituting the coater dice of the slide hopper coating apparatus, the falling liquid film at each interface of the layered high refractive index layer coating liquid and the low refractive index layer coating liquid and the simultaneous multilayer flow The shear rate on the high-viscosity liquid side of the velocity component parallel to the slide surface is the shear rate (d) at the interface.
Moreover, the time for the interface of the falling liquid film to flow down on each block (slide surface) is defined as the falling time (t).

  Here, in simultaneous multilayer coating, a numerical value (d × t) can be calculated for each interface on each block. The numerical value represented by (d × t) calculated on each block increases as the number of stacks increases. For each interface, the integrated value Σ (d × t) of (d × t) after the interface represented by (d × t) is first formed and before the falling liquid film is applied. The simultaneous multilayer coating is performed under the condition that the maximum value of is 50 or less.

  Hereinafter, the specific form of simultaneous multilayer coating in the manufacturing method of an optical reflective film is demonstrated. In the method for producing an optical reflective film using a slide hopper coating apparatus, it is preferable to perform a simultaneous multilayer coating process under the above-described conditions after the following preparation process, circulation process, and supply process. Furthermore, it is preferable to perform a drying process after the simultaneous multilayer coating process.

[Preparation process]
In a preparation process, the coating liquid which forms the high refractive index layer and low refractive index layer of an infrared shielding film is prepared, respectively. In the preparation process, a preparation kettle, a liquid feeding device and a filtration device are used.

  The preparation kettle is a container for preparing a polymer-containing coating solution. The method for preparing the coating solution is not particularly limited, and, for example, the metal oxide particles, the water-soluble polymer, and the additive added as necessary are stirred and mixed together with the solvent. 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 method for preparing the coating solution is appropriately determined for each coating solution. The preparation kettle is connected to the storage kettle in order to supply the coating liquid to the kettle included in the circulation process.

  The liquid feeding device is provided in a path for transferring the coating liquid from the preparation kettle. The liquid feeding device is, for example, a pump, and can control the transfer of the prepared coating liquid and stop of the transfer. The liquid feeding device can appropriately set the flow rate and speed of the coating liquid when the coating liquid is transferred.

  The filtration device is provided in a path for transferring the coating liquid from the preparation kettle. The filtering device removes foreign matter mixed in the coating solution, bubbles generated in the coating solution, and aggregated foreign matter. The coating liquid from which the foreign matter has been removed is sent to a circulation process.

(Coating solution)
As the coating solution for the low refractive index layer and the coating solution for the high refractive index layer, from the point that mixing between layers can be suppressed by performing the setting described later on the coating film after coating, water-soluble resins such as polyvinyl alcohols and the like 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, more preferably 20 to 180 mPa · s. 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. 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%.

  Note that the second metal oxide particles used in the coating solution for the high refractive index layer are preferably prepared separately in the state of a dispersion 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.

(solvent)
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 and propylene. Examples include ethers such as 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, simplicity of operation, etc., the solvent for the coating solution is particularly preferably water or a mixed solvent of water and methanol, ethanol, or ethyl acetate.

(Water-soluble polymer)
Examples of the water-soluble polymer used in the coating solution for the high refractive index layer and the coating solution for the low refractive index layer include, for example, polyvinyl alcohols, polyvinyl pyrrolidones, polyvinyl butyral, polyacrylic acid, and acrylic acid-acrylonitrile copolymer. , Acrylic resins such as potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic ester copolymer, or acrylic acid-acrylic ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer Styrene acrylic acid such as polymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, or styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer Resin, styrene-sodium styrenesulfonate copolymer Polymer, styrene-2-hydroxyethyl acrylate copolymer, styrene-2-hydroxyethyl acrylate-potassium styrenesulfonate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinylnaphthalene-acrylic Vinyl acetate copolymers such as acid copolymers, vinyl naphthalene-maleic acid copolymers, vinyl acetate-maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers, and Synthetic water-soluble polymers such as salts thereof; 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 agents, from the viewpoint of handling during production and film flexibility. Examples include sugars (particularly celluloses). These water-soluble polymers may be used alone or in combination of two or more.

  Polyvinyl alcohol 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.

The polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate preferably has an average degree of polymerization of 1000 or more, particularly preferably an average degree of polymerization of 1500 to 5000, more preferably 2000 to 5000. . This is because when the polymerization degree of polyvinyl alcohol is 1000 or more, there is no cracking of the coating film, and when it is 5000 or less, the coating solution is stabilized. 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 mol%, and more preferably 80 to 99.5 mol% in terms of solubility in water.

  The coating solution for the high refractive index layer and the coating solution for the low refractive index layer are not only polyvinyl alcohol having an average polymerization degree of 1000 or more, but also a low polymerization degree high polymerization having a polymerization degree of 100 to 500 and a saponification degree of 95 mol% or more. It is preferable to contain activated polyvinyl alcohol. By containing such a low polymerization degree highly saponified polyvinyl alcohol, the stability of the coating solution is improved.

  At least one of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer may contain modified polyvinyl alcohol partially modified in addition to normal polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate. Good. 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 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, 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 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 copolymers of vinyl compounds having a hydrophobic group and vinyl alcohol, silanol-modified polyvinyl alcohol having a silanol group, reactive group modification having a reactive group such as an acetoacetyl group, a carbonyl group, or a 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 may be added to the coating solution for the low refractive index layer and the coating solution for the high refractive index layer as necessary. Examples of 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 include, for example, JP-A-57-74193, JP-A-57-87988, and JP-A No. 62-261476, JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-146591, JP-A-1 -95091, and anti-fading agents, various anionic, cationic or nonionic surfactants described in JP-A-3-13376, JP-A-59-42993, JP-A-59-52689 , Whitening agents, sulfuric acid, phosphoric acid, acetic acid, citric acid described in JP-A-62-2280069, JP-A-61-228771, and JP-A-4-219266 PH adjusters such as sodium hydroxide, potassium hydroxide, potassium carbonate and sodium acetate, antifoaming agents, lubricants such as diethylene glycol, preservatives, antifungal agents, antistatic agents, matting agents, heat stabilizers, antioxidants And various known additives such as flame retardants, crystal nucleating agents, inorganic particles, organic particles, thickeners, lubricants, infrared absorbers, dyes and pigments.

Moreover, it is preferable that the coating liquid for low refractive index layers and the coating liquid for high refractive index layers contain a hardening | curing agent as an additive. 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. As the curing agent, known ones other than boric acid and its salts can be used. In general, a compound having a group capable of reacting with polyvinyl alcohols or a reaction between different groups of polyvinyl alcohols is promoted. Such compounds can be appropriately selected and used. Furthermore, 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.
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.

  Boric acid or a salt thereof refers to an oxygen acid having a boron atom as a central atom and a salt thereof, specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, and octaboron. Examples include acids and their salts. Boric acid having a boron atom as a curing agent and a salt thereof may be used as a single aqueous solution or as a mixture of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax.

  The 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.

  As a hardening | curing agent, it is preferable from a viewpoint of using a boric acid, its salt, and / or borax to suppress interlayer mixing more. When boric acid and its salts and / or borax are used, metal oxide particles and OH groups of polyvinyl alcohols, which are water-soluble binder resins, form a hydrogen bonding network, resulting in high refraction. It is thought that interlayer mixing between the refractive index 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.

[Circulation process]
In the circulation step (coating liquid circulation system), the prepared coating liquid is circulated while maintaining proper physical properties. In the circulation process, a storage pot, a liquid feeding device, a dispersion device, a defoaming device, a filtration device, and a circulation path are used. The defoaming device and the filtering device are provided in the circulation path.

  The storage pot stores a coating liquid for continuous supply. The storage tank is preferably provided with a stirring device for circulating the coating liquid even inside the storage tank. Thereby, the physical property of the coating liquid in a storage pot can be made uniform. A circulation path for returning the coating liquid transferred from the storage tank back to the storage tank is connected to the storage tank. Further, a supply path for sending the coating liquid to the supply process and the coating process is also connected to the storage hook.

  The liquid feeding device is provided on the circulation path. Examples of the liquid delivery device include a pump. The liquid feeding device controls the transfer of the coating liquid stored in the storage pot and the stop of the transfer. The liquid feeding device can appropriately set the flow rate and speed of the coating liquid when transferring the coating liquid.

  The dispersing device is provided on the circulation path. The dispersion device performs dispersion treatment or shear treatment on the coating solution. Thereby, in the coating liquid, the bonds (van der Waals bonds, etc.) between the molecules of the polymer and within the molecules are broken, entanglement of the molecules is eliminated, and the viscosity of the coating liquid is reduced.

  The configuration of the dispersing device is not particularly limited as long as the coating liquid can be dispersed and sheared. For example, a commercially available milder, a pressure homogenizer, a high-speed rotary shearing homogenizer, or the like can be used. When the dispersion device is a milder, for example, the coating liquid that flows between the fixed tooth and the movable tooth is subjected to a dispersion process and a shear process by a shearing force generated by a velocity gradient between the fixed tooth and the movable tooth. Examples of the milder that can be used as the dispersing device include Ebara Milder (manufactured by Ebara Corporation), Milder (manufactured by Taiheiyo Kiko Co., Ltd., MDN306), and the like.

  FIG. 1 is a schematic diagram of a milder used as a dispersing device for a circulation process. The milder of FIG. 1 has a stator tooth 31 that is a fixed tooth and a rotor tooth 32 that is a rotating tooth. The shear target liquid 34 moving in the gap (shear gap) La between the stator teeth 31 and the rotor teeth 32 has a velocity gradient (shear velocity) in the radial direction of the rotor teeth 32. Due to this speed gradient, an internal frictional force (shearing force) is generated between the stator teeth 31 and the rotor teeth 32. Since the introduction of the shear target liquid 35 into the shear gap La is performed in the radial direction from the slit gap of the rotor teeth 32, the shear target liquid 34 flowing into the shear gap La and the introduced shear target liquid 35 continuously collide with each other. repeat. That is, according to the milder of FIG. 1, shearing and mixing are continuously performed on the liquid to be sheared.

  The rotational speed of the milder when used as a dispersing device is preferably 1000 to 9000 rpm, more preferably 2000 to 8000 rpm. Moreover, in order to supply a coating liquid to a dispersion process, 3-10 L / min is preferable and, as for the flow volume of the coating liquid in a circulation path, More preferably, it is 5-10 L / min. When the rotational speed of the milder and the flow rate of the coating liquid are within this range, there is an effect of preventing the coating liquid from aggregating.

  The minimum gap between the stator teeth and the rotor teeth in the shear gap is preferably 0.05 to 0.5 mm, and more preferably 0.1 to 0.4 mm. The shear rate can be adjusted by appropriately setting the minimum gap between the stator teeth and the rotor teeth in the shear gap and the rotational speed of the rotor teeth.

  The defoaming device removes bubbles contained in the coating liquid and dissolved air dissolved in the coating liquid. As a defoaming method, for example, a method of separating bubbles and liquid by centrifugal force and discharging the bubbles by evacuation, or a method using ultrasonic waves can be considered. However, any defoaming apparatus may be used as long as defoaming is possible.

  The filtering device removes foreign matters mixed in the coating liquid, bubbles generated in the coating liquid, and aggregated foreign substances. The coating liquid from which the foreign matter has been removed is returned again to the storage tank through the circulation path.

  As described above, in the circulation step, the coating liquid is transferred from the storage kettle to the circulation path, treated by the dispersing device, the defoaming device, and the filtration device, and then returned to the storage kettle. Here, a part of the coating liquid accommodated in the storage tank is sent to the supply process through a supply path connected to the storage tank. The coating liquid that has returned to the storage pot moves while being stirred in the storage pot, and then is transferred again to the circulation path, and the above processing is repeated. In this way, in the circulation step, physical properties such as the viscosity of the coating solution are applied by continuously performing dispersion treatment, defoaming treatment, filtration treatment, etc. at an appropriate strength while circulating the prepared coating solution. It can be kept within the range suitable for. The processing strength of the dispersion device, the defoaming device and the filtration device in the circulation process is such that the physical properties of the coating liquid are kept within an appropriate range depending on the application of the infrared shielding film and the properties of the coating liquid used. It can set suitably as follows.

  In the circulation process, the number of times the coating liquid is circulated is not predetermined, and a predetermined flow rate of the coating liquid is supplied from the storage tank to the circulation path according to the setting of the liquid feeding device and the like. Sequentially sent and circulated. Since the circulated coating liquid is returned to the storage kettle and stirred, the physical properties of the entire coating liquid contained in the storage kettle can always be kept in a state suitable for coating.

  Further, the order of the dispersing device, the defoaming device, and the filtering device on the circulation path can be changed as appropriate. In addition, one device that integrates the functions of a plurality of the above devices may be provided for the circulation process. For example, a dispersion defoaming device in which functions of the dispersion device and the defoaming device are integrated may be provided in the circulation process. Further, in the circulation step, a device other than the above may be provided, or any of the above devices may not be provided.

[Supply process]
In the supplying step, the prepared and circulated coating solution is supplied to the simultaneous multilayer coating step. A supply process uses a liquid feeding apparatus, a flow meter, a defoaming apparatus, a filtration apparatus, and a supply path. The supply path is a path for supplying the coating liquid from the storage tank in the circulation process to the coating process. The liquid feeding device, the flow meter, the defoaming device, and the filtration device are provided in the supply path.

  The liquid feeding device sends the coating liquid transferred from the storage tank in the circulation process to each device provided in the supply path. The liquid feeding device is, for example, a pump, and can control the transfer of the prepared coating liquid and stop of the transfer. The liquid delivery device can appropriately set the flow rate and speed of the coating liquid when the coating liquid is transferred.

  The flow meter is a device that measures the flow rate of the coating liquid passing through the supply path. The flow rate of the liquid feeding device is appropriately controlled according to the flow rate of the coating liquid measured by the flow meter. As the flow meter, for example, a Coriolis type, electromagnetic type, flap type, hot wire type, Karman vortex type, or negative pressure sensing type flow meter is used. In addition to the flow meter or instead of the flow meter, a pressure gauge that measures the pressure of the coating liquid in the supply path may be provided.

  The defoaming device removes bubbles contained in the coating liquid and dissolved air dissolved in the coating liquid. As a defoaming method, for example, a method of separating bubbles and liquid by centrifugal force and discharging the bubbles by evacuation, or a method using ultrasonic waves can be considered. However, any defoaming device may be used as long as defoaming is possible.

  The filtering device removes foreign matters mixed in the coating liquid, bubbles generated in the coating liquid, and aggregated foreign substances. The coating liquid from which the foreign matter has been removed is sent to the coating process through the supply path.

  Note that the order of the flow meter, the defoaming device, and the filtering device on the supply path can be changed as appropriate. Moreover, one apparatus which integrated the function of the said several apparatus may be provided for a supply process. In the supplying step, an apparatus other than the above may be provided, or any of the above apparatuses may not be provided.

[Simultaneous multilayer coating process]
Through the above supply step, the coating solution for the high refractive index layer and the coating solution for the low refractive index layer are supplied to the simultaneous multilayer coating step. In the simultaneous multilayer coating process, a high refractive index coating solution and a low refractive index coating solution are stacked on the slide surface using a slide hopper coating device. And the high refractive index layer and the low refractive index layer are formed by apply | coating this laminated | stacked coating liquid for high refractive index and the coating liquid for low refractive index to a base film.

  FIG. 2 shows an example of a schematic diagram of a slide hopper coating apparatus used in the simultaneous multilayer coating process. 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. 2, a four-layer simultaneous multi-layer coating mode is shown), and the coating liquid 4 flows down thereon. Further, the coater die 3 is fixed to a coater die holding base (not shown) at an angle 8 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 FIG. 2, the center of the back roll 2 and the liquid contact part 6 are arranged with an angle 7, and the running surface and the slide surface of the base film 1 are arranged with an angle 9.

  In simultaneous multilayer coating, the velocity distribution of the simultaneous multilayer flow on the slide surface in the slide hopper coating apparatus is calculated by simulation. In the simulation, by calculating the velocity distribution of the simultaneous multi-layer flow on the slide surface, the shear rate (d) and the flow-down time (t) on the high viscosity liquid side at each interface between the stacked coating liquids in the simultaneous multi-layer flow Then, (d × t) at each interface is obtained, and an integrated value Σ (d × t) of (d × t) from the formation of each interface to application is calculated for each interface. Then, the simultaneous multilayer coating is performed under the condition that the cumulative value Σ (d × t) ≦ 50 of the interface where the value of the cumulative value Σ (d × t) is maximum, thereby causing the occurrence of grainy unevenness due to the simultaneous multilayer coating. Can be suppressed.

(Shear rate d)
First, the shear rate (d) on the high-viscosity liquid side of each layer interface in the simultaneous multi-layer flow simulation will be described.
The shear rate on the slide surface is a laminar flow and is expressed by the following formula in the case of a single layer flow, and can be manually calculated.

  V: Sliding surface flow velocity, y: Sliding surface thickness, ρ: Density, μ: Viscosity, θ: Sliding surface tilt angle, D: Sliding surface film thickness

  On the other hand, in the case of simultaneous multi-layer flow, since manual calculation is not possible, calculation with simulation software is required. As simulation software, a finite element method, a finite volume method, a difference method, or the like can be applied. In this embodiment, the finite element method is applied. Hereinafter, an outline of optimization of simultaneous multilayer coating by simulation will be described.

  FIG. 3 shows a state of simultaneous multi-layer flow on the slide surface in the slide hopper coating apparatus. In FIG. 3, the coater die 3 is composed of five blocks (block 11A, block 11B, block 11C, block 11D, and block 11E). Then, from each slit between the block 11A to the block 11E, except on the block 11A, on the slide surface 12B, slide surface 12C, slide surface 12D, and slide surface 12E on each block 11B, 11C, 11D, 11E The coating liquid is supplied and a simultaneous multi-layer flow is formed.

In the simultaneous multi-layer flow shown in FIG. 3, firstly, the first coating liquid layer S1 is formed on the slide surface 12B of the block 11B by supplying the first coating liquid from the slit between the block 11A and the block 11B. Is done.
Furthermore, the second coating liquid is supplied from the slit between the block 11B and the block 11C below the first coating liquid layer S1, so that the first coating liquid layer S1 is below the first coating liquid layer S1 on the slide surface 12C of the block 11C. Two coating liquid layers S2 are formed.
Similarly, when the third coating liquid is supplied from the slit between the block 11C and the block 11D below the second coating liquid layer S2, the slide surface 12D of the block 11D is below the second coating liquid layer S2. A third coating liquid layer S3 is formed. Thereby, a stacked flow of the third coating liquid layer S3, the second coating liquid layer S2, and the first coating liquid layer S1 is formed on the slide surface 12D of the block 11D.
Then, the fourth coating liquid is supplied from the slit between the block 11D and the block 11E below the third coating liquid layer S3, so that the second coating liquid layer S3 is below the third coating liquid layer S3 on the slide surface 12E. Four coating liquid layers S4 are formed. Thereby, a stacked flow of the fourth coating liquid layer S4, the third coating liquid layer S3, the second coating liquid layer S2, and the first coating liquid layer S1 is formed on the slide surface 12E of the block 11E.
Thus, in the slide surface flow, the two-layer flow is first formed by the coating liquid supplied from the coater die 3, and then increases to the three-layer, four-layer,. Thus, a simultaneous multi-layer flow is formed.

  Further, in the simultaneous multi-layer flow of this example, a configuration in which the coating liquid for the high refractive index layer (high viscosity liquid) and the coating liquid for the low refractive index layer (low viscosity liquid) are alternately laminated except for the lowermost layer and the uppermost layer. Have As described above, in a system in which liquids having greatly different viscosities are alternately laminated, the shear rate (d) at the interface between the high viscosity liquid layer and the low viscosity liquid layer is greatly different between the high viscosity liquid side and the low viscosity liquid side. FIG. 4 shows the relationship between the shear rate (d) on the slide surface and the slide surface film thickness (y) in a system in which high viscosity liquid and low viscosity liquid are alternately laminated. In FIG. 4, in the N layer flow, the coating liquid layer (Nth coating liquid layer) constituting the lowermost layer of the simultaneous multilayer flow is a low viscosity liquid layer, and the coating liquid layer formed on the Nth coating liquid layer (N-1th coating liquid layer) is a high-viscosity liquid layer, and hereinafter, a system in which low-viscosity liquid layers and high-viscosity liquid layers are alternately laminated is shown.

  As shown in FIG. 4, the shear rate is greatly different between the low refractive index layer coating liquid (low viscosity liquid) layer and the high refractive index layer coating liquid (high viscosity liquid) layer. In the simultaneous multi-layer flow, the shear rate of the Nth coating liquid layer formed immediately above the slide surface is large, and the shear rate decreases as the slide surface film thickness direction increases. That is, in the simultaneous multi-layer flow, in the case of the same viscosity liquid, the shear rate becomes lower as the coating liquid layer is formed in a higher layer. Furthermore, at the outermost surface of the simultaneous multi-layer flow, the shear rate is zero.

  As shown in FIG. 4, in the simultaneous multi-layer flow, the shear rate in the low viscosity liquid layer is large and the shear rate in the high viscosity liquid layer is small. For this reason, the shear rate at the interface between the high-viscosity liquid layer and the low-viscosity liquid layer can be expressed by different values on the low-viscosity liquid layer side and the high-viscosity liquid layer side. Here, in this simulation in the simultaneous multi-layer flow, the shear rate on the high-viscosity liquid side is used for the shear rate of each interface represented by different values on the high-viscosity liquid layer side and the low-viscosity liquid layer side. Thus, by using the shear rate on the high-viscosity liquid side as the shear rate (d) at the interface of each coating liquid layer, the shear stress at the interface that differs greatly between the high-viscosity liquid side and the low-viscosity liquid side is uniformly determined. Can be prescribed.

(Flow time t)
Next, the flow time (t) at each interface in the simultaneous multi-layer flow simulation will be described.
The flow time (t) of each interface is the time for each interface of the simultaneous multi-layer flow to flow on the slide surface of each block constituting the coater die. This flow-down time (t) is defined for each block. Accordingly, in the configuration illustrated in FIG. 3, the flow time (t) is the thickness of each block (block 11B, block 11C, block 11D, block 11E) constituting the coater die 3 and the flow velocity (interface flow) of each interface. Depends on the speed u).

  In the simultaneous multi-layer flow from the first coating liquid layer S1 to the Nth coating liquid layer SN, a new interface is generated for each slide surface on each block. Here, each interface is defined from the upstream side as a first interface, a second interface, a third interface,.

For example, in the configuration illustrated in FIG. 3, the interface between the first coating liquid layer S1 and the second coating liquid layer S2 generated on the slide surface 12C of the block 11C is defined as an eleventh interface (interface dt ₁₁ ). Further, the interface between the first coating liquid layer S1 and the second coating liquid layer S2 generated on the slide surface 12D of the block 11D is defined as a twelfth interface (interface dt ₁₂ ), and is generated on the slide surface 12E of the block 11E. An interface between the first coating liquid layer S1 and the second coating liquid layer S2 is defined as a thirteenth interface (interface dt ₁₃ ).

Similarly, the second coating fluid layer S2 for generating on the slide surface 12D of the block 11D the interface between the third liquid layer S3, 21 and an interface (interface _{dt 21),} occurs on the slide surface 12E of block 11E The interface between the second coating liquid layer S2 and the third coating liquid layer S3 is referred to as a 22nd interface (interface dt ₂₂ ). Further, an interface between the third coating liquid layer S3 and the fourth coating liquid layer S4 generated on the slide surface 12E of the block 11E is defined as a 31st interface (interface dt ₃₁ ).

Then, flow time in the 11 interface _{dt 11 (t 11)} includes a surface falling velocity _{u 11} of the 11 interface _{dt 11,} defined by the thickness L1 of the block 11C. Similarly, the interface flow speeds u ₁₂ , u ₁₃ , u ₂₁ , u ₂₂ , u ₃₁ ,... At each interface and the thicknesses L 1, L 2, L 3,. The flow time (t) for each interface dt is defined by.

Thus, in the configuration to illustrate in FIG. 3, the first coating liquid layers S1 at the interface between the second coating fluid layer S2, the interface _{dt 11,} interface _{dt 12,} interface _dt 13, the ... interface _{dt 1N-1} at each interface, efflux time _t 11 _{~t 1N-1} are defined respectively.
Similarly, the second coating fluid layer S2 at the interface between the third liquid layer S3, the interface _{dt 21,} interface _dt 22, at each interface of ... interface _{dt 2N-2,} falling each time _{t 21} ~ t _2N-2 is defined. A third liquid layer S3 in the interface between the fourth coating solution layer S4, the interface _{dt 31,} interface _dt 32, at each interface of ... interface _{dt 3N-3, t} 31 flow time each _{~t 3 N- 3} is defined.

(D × t at each interface)
By defining the shear rate (d) and the flow time (t) at each interface dt as described above, the product (d × t) of the shear rate (d) and the flow time (t) for each interface dt is obtained. Can be sought. Furthermore, each interface between the coating liquid layers from the first coating liquid layer S1 to the Nth coating liquid layer SN is applied to the film from (d × t) of the interface dt _X1 that first occurs for each interface. By integrating all of the interfaces dt _XX generated up to (d × t), an integrated value Σ (d × t) for each interface can be obtained.

  An outline of the calculation method in the case of the N-layer flow is shown below for the integrated value Σ (d × t) obtained for each interface described above.

(Upper layer thickness D1, lower layer thickness D2)
In addition, in the slide surface flow in simultaneous multilayer coating, the flow down speed is different for each coating liquid layer, and therefore the flow down film thickness of each coating liquid layer is different on the slide surface even in the case of the same coating film thickness. The thickness of each layer is also calculated by simulation software, and the upper layer thickness (D1) and the lower layer thickness (D2) are obtained. For example, in the configuration illustrated in FIG. 3, the upper layer thickness (D1) at the interfaces dt _{11 to} dt ₁₃ ... Is the falling film thickness at each interface of the first coating liquid layer S1, and the lower layer thickness ( D2) is the falling film thickness at each interface of the second coating liquid layer S2.

Then, in the same manner as the above integrated value Σ (d × t), for each interface between the coating liquid layers from the first coating liquid layer S1 to the Nth coating liquid layer SN, from the interface dt _X1 to the interface dt _XX. By integrating all (d × (D1 / D2) × t), an integrated value Σ (d × (D1 / D2) × t) for each interface can be obtained.

(Maximum value of integrated value Σ (d × t), maximum value of integrated value Σ (d × (D1 / D2) × t))
In the simultaneous multilayer coating process using the slide hopper coating apparatus, simultaneous multilayer coating is performed under the condition that the maximum value of the integrated value Σ (d × t) for each interface calculated by simulation is 50 or less. By setting the maximum value of the integrated value Σ (d × t) to 50 or less, it is possible to suppress the occurrence of grainy unevenness. Furthermore, the uniformity in the width direction of the optical reflection film is increased, and the occurrence of color unevenness in the width direction can be suppressed.
The maximum value of the integrated value Σ (d × t) is more preferably 30 or less. When the maximum value of the integrated value Σ (d × t) is 30 or less, the above-described effects can be obtained more remarkably.

  Furthermore, the maximum value of the integrated value Σ (d × (D1 / D2) × t) calculated by the above simulation is preferably 30 or less, and more preferably 25 or less. When the maximum value of the integrated value Σ (d × (D1 / D2) × t) is within the above range together with the maximum value of the integrated value Σ (d × t), the above-described operational effects can be obtained more remarkably. .

  In the slide surface flow, the shear rate difference between the upper and lower interfaces and the film thickness difference between the upstream and downstream are caused by the difference in viscosity. For this reason, calculation application by the above simulation can be preferably applied to a system in which the viscosity difference between adjacent layers is 100 cp or more. In particular, it can be preferably applied to a system having a viscosity difference of 150 cp or more.

  In addition, since the maximum value of the integrated value Σ (d × t) and the maximum value of the integrated value Σ (d × (D1 / D2) × t) are not more than the above values, the film formation quality of the simultaneous multilayer coating is improved. The detailed mechanism of action has not been elucidated. As a result of simulations and experiments, the above findings indicate that the maximum value of the integrated value Σ (d × t) and the maximum value of the integrated value Σ (d × (D1 / D2) × t) are not more than the above values. This is because the coating quality of the multilayer coating is improved.

  The maximum value of the integrated value Σ (d × t) and the maximum value of the integrated value Σ (d × (D1 / D2) × t) are, for example, the viscosity of the coating solution for the low refractive index layer and the coating solution for the high refractive index layer. , The thickness of each block constituting the coater die of the slide hopper coating device (flowing distance), the falling film thickness (flow rate) of the coating liquid, the tilt angle of the slide surface, and the number of layers for simultaneous multi-layer coating (flowing distance) By appropriately setting each parameter, it can be adjusted to the above value or less.

Although the influence on the maximum value of the integrated value Σ (d × t) and the maximum value of the integrated value Σ (d × (D1 / D2) × t) by these parameters cannot be generally described, specifically, It has the following tendencies.
For example, when the viscosity of the coating solution increases, the shear rate (d) decreases and the flow time (t) increases. At this time, the decrease rate of the shear rate (d) due to the increase in viscosity often exceeds the increase rate of the flow time (t). For this reason, if the viscosity of a coating liquid is mentioned, it will become the tendency for the value of (dxt) to fall as a result.
When the thickness of the block and the number of layers are increased, the flow distance of the simultaneous multi-layer flow increases, and the flow time (t) increases. For this reason, the value of (d × t) tends to increase.
When the inclination angle of the slide surface becomes small, the shear rate (d) decreases and the flow time (t) increases. However, since the rate of decrease in shear rate is greater than the rate of increase in flow time, (d × t) tends to be small.
Further, when the coating film thickness (flow rate) is large, the shear rate (d) increases, but the flow rate increases and the flow time decreases, but the rate of decrease in the flow time is larger, so (d × t) tends to be smaller.

[Drying process]
The coating film is dried by applying the above-mentioned simultaneous multilayer coating on the base film, and then cooling (setting) the temperature of the formed coating film to preferably 1 to 15 ° C., and then drying at 10 ° C. or higher. It is preferable to carry out under conditions. 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, hot air of 50 ° C. is blown on the coated film after setting for 1 to 5 minutes for drying. Moreover, as a cooling (set) system immediately after application, it is preferable to carry out by a horizontal set system from the viewpoint of improving the uniformity of the formed coating film.

  As a drying method, warm air drying, infrared drying, and microwave drying are used. Moreover, the drying of a multistage process is preferable rather than the drying by a single process, and it is more preferable to perform a drying process on the conditions that the temperature in a reduction rate drying part becomes higher than a constant rate drying part. 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, cooling (set) refers to lowering the temperature of the coating film by applying cold air or the like to increase the viscosity of the coating composition to decrease the fluidity of the substances in each layer and each layer, It means a process of gelling. 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, the components in the layer may not be sufficiently cooled. 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.

[Optical reflector]
The optical reflection film produced by the above-described manufacturing method can shield light having a predetermined wavelength by controlling the optical film thickness and the like of the laminate, so that it can be used as an optical reflector according to the light to be shielded. It can be applied to various uses. For example, an ultraviolet shielding body using an ultraviolet shielding film that reflects ultraviolet light, a decorative body using a light-colored film that reflects visible light, an infrared shielding body using an infrared shielding film that reflects infrared light, a predetermined wavelength And a decorative body using a metallic glossy film that reflects the light.
Hereinafter, an infrared shielding body using an infrared shielding film as a typical example will be described as an application of the optical reflection film. In addition, the use of an optical reflection film is not limited to an infrared shielding body.

(Infrared shield)
The infrared shielding film which is an optical reflection film 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. Used. Moreover, it is used suitably also as an infrared shielding film for motor vehicles of the structure by which the optical reflection film was inserted | pinched between glass and glass, such as laminated glass for motor vehicles. In this case, since the infrared shielding film can be sealed with glass, it is preferable from the viewpoint of durability.

  In particular, the infrared shielding film is suitably used as an infrared shielding body having a configuration in which the infrared shielding film is bonded to a substrate such as glass or a glass substitute resin through an adhesive layer (adhesive layer). In an infrared shielding body, it is preferable that an infrared shielding film is arrange | positioned rather than a base | substrate at the sunlight (heat ray) incident surface side.

  In the infrared shielding body, the thickness of the substrate is not particularly limited, but is usually 0.1 mm to 5 cm. As a base used for the infrared shielding body, a plastic base, a metal base, a ceramic base, a cloth base, and the like can be used, and various forms of bases such as a film, a plate, a sphere, a cube, and a cuboid can be used. Can be used. 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, phenol resin, diallyl phthalate resin, polyimide resin, Examples thereof include urethane resin, polyvinyl acetate resin, polyvinyl alcohol resin, styrene resin, vinyl chloride resin, metal plate, and ceramic. 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 used as the infrared shielding body can be produced by a known method such as extrusion molding, calendar molding, injection molding, hollow molding, compression molding or the like.

  As the substrate, a plate-shaped ceramic substrate is preferable, and an infrared shielding body in which an infrared shielding film 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. Moreover, as an infrared shielding body, the form which provided the infrared shielding film on both surfaces of glass may be sufficient, for example, the adhesive layer or the adhesive layer is coated on both surfaces of the infrared shielding film, and both surfaces of an infrared shielding film are provided. A laminated glass-like form in which glass is bonded together may be used.

  As an adhesive layer (adhesive layer) for bonding the infrared shielding film and the substrate, it is preferable to use an adhesive or an adhesive mainly composed of a photocurable or thermosetting resin. The adhesive layer preferably has durability against ultraviolet rays, and it is preferable to use an acrylic adhesive or a silicone adhesive. Furthermore, it is preferable to use an acrylic adhesive from the viewpoint of adhesive properties and cost. In particular, since it is easy to control the peel strength, it is preferable to use a solvent system in the acrylic adhesive. 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 may be used as the adhesive layer or the adhesive layer. For example, plastic polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., Mitsubishi Monsanto, etc.), ethylene-vinyl acetate copolymer (manufactured by DuPont, Takeda Pharmaceutical Co., Ltd., duramin), modified ethylene-vinyl acetate copolymer (Tosoh Corporation) For example, Mersen G) manufactured by the company can be used. In the adhesive layer or the pressure-sensitive adhesive layer, an ultraviolet absorber, an antioxidant, an antistatic agent, a heat stabilizer, a lubricant, a filler, a coloring agent, an adhesion (adhesion) adjusting agent and the like may be appropriately added and blended.

  As a method of providing the infrared shielding film of this embodiment on the substrate, an adhesive layer or an adhesive layer is applied to the infrared shielding film as described above, and the infrared shielding film is attached to the substrate via the adhesive layer or the adhesive layer. The attaching method is preferably used. As a bonding method, a dry bonding method in which a film is directly bonded to a substrate, a method in which the above-described water bonding method is performed, and the like can be applied. The bonding between the base and the infrared shielding film is performed in order to prevent air from entering between the base and the infrared shielding film and to facilitate the positioning of the infrared shielding film on the base. From this point of view, it is preferable to carry out by a water sticking method.

  In the infrared shielding film and the infrared shielding body, the heat insulation performance and the solar heat shielding performance are generally measured according to JIS R3209: 1998 (multi-layer glass), JIS R3106: 1998 (transmittance, reflectance, emissivity, It can be determined by a method based on JIS R3107: 1998 (Calculation method of thermal resistance of plate glass and heat transmissivity in architecture).

The solar transmittance, solar reflectance, emissivity, and visible light transmittance are measured by the following methods (1) and (2).
(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, solar reflectance, solar absorption rate, and modified 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 the following methods (1) to (3).
(1) The thermal resistance of the multilayer glass is calculated 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.

<Preparation of the infrared shielding film of Example 1>
[Preparation of coating solution (preparation process)]
(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-I03, polymerization degree 300, saponification degree 98.5 mol%, Co., Ltd.) 5 mass% of Kuraray Co., Ltd. was added 2 mass parts of an aqueous solution and 10 mass parts of a 3 mass% boric acid aqueous solution, and then heated to 40 ° C. with stirring, polyvinyl alcohol (PVA-117, polymerization degree 1700, 20 mass parts of 5 mass% aqueous solution of saponification degree 98.5 mol%, made by Kuraray Co., Ltd., and 1 mass of 1 mass% aqueous solution of surfactant (Lapisol (registered trademark) A30, manufactured by NOF Corporation) A low refractive index layer coating solution L1 was prepared by adding 55 parts by mass of pure water. However, the amount of pure water was adjusted so that the low refractive index layer coating liquid L1 had a 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% by mass) is gradually added. did. 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, so that SiO ₂ having a solid content concentration of 20% by mass was attached (coated) to the surface. A titanium oxide sol (hereinafter simply referred to as “silica-attached titanium oxide sol”) was obtained.

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

[Distributed processing (circulation process)]
The dispersion process in the circulation process was performed on the coating liquid H1 for the high refractive index layer and the coating liquid L1 for the low refractive index layer prepared by the above-described method. Dispersion treatment was performed at a rotational speed of 3000 rpm using a milder disperser MDN306 manufactured by Taiyo Kiko as a disperser. The flow rate of the coating liquid fed to the dispersing device in the circulation process was 8 L / min.

[Production of infrared shielding film (simultaneous multilayer coating process)]
Using a slide hopper coating device capable of coating 40 layers, a polyethylene terephthalate film (made by Toyobo Co., Ltd.) having a thickness of 50 μm while keeping the low refractive index layer-use cloth liquid L1 and the high refractive index layer coating liquid H1 at 40 ° C. , Cosmo Shine (registered trademark) A4300, double-sided easy-adhesive layer) were alternately applied in total 38 layers simultaneously.
At this time, from the base film side, the first layer (lowermost layer) and the second layer are the low refractive index layers, the third and subsequent layers are alternately the high refractive index layers and the low refractive index layers, and the uppermost layer is The liquid feeding tank was pressurized so as to be a low refractive index layer, and the coating liquid was fed to the slide hopper coating apparatus. 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). In this way, an infrared shielding film having a total of 40 layers at the maximum of the low refractive index layer and the high refractive index layer was produced.

[simulation]
The simulation was performed by a computer “OPTIPLEX 9020” manufactured by Dell using finite element method software “HyperWorks” manufactured by Altair.
Table 1 below shows the number of simultaneous multi-layer coating layers, simulation results, and viscosity differences between adjacent layers in each Example and Comparative Example. The viscosity of the coating solution was measured with a drop viscometer.

<Preparation of the infrared shielding film of Examples 2-5>
The infrared shielding films of Examples 2 to 5 were produced in the same manner as in Example 1 except that the number of coating layers and the conditions described in Table 1 below were used.

<Production of infrared shielding films of Comparative Examples 1 and 2>
The infrared shielding films of Comparative Examples 1 and 2 were produced in the same manner as in Example 1 except that the number of coating layers and the conditions described in Table 2 below were used.

[Evaluation of infrared shielding film]
About the infrared shielding film produced in Examples 1-5 and Comparative Examples 1-2, the following performance evaluation of the grain-like nonuniformity by visual observation and the width direction color nonuniformity was performed. For the color unevenness in the width direction, an infrared shielding film was laid on a black paper and visually evaluated with reflected light. The evaluation results are shown in Tables 3 and 4 below.

(Visual evaluation of grain-like unevenness and width direction color unevenness)
○ ○: No occurrence ○: Slight occurrence Δ: Weak occurrence ×: Strong occurrence

  In addition, it is necessary for the infrared shielding film not to generate | occur | produce strongly ("x") in the visual evaluation result of the grain-like unevenness and the width direction color unevenness. Woody unevenness and widthwise color unevenness may occur weakly ("△"), but it is preferable that all are slightly generated ("○") or more, and no occurrence ("OO"), Particularly preferred.

  As is apparent from the results of Tables 3 and 4, the shear rate (d) on the high-viscosity liquid side when the coating liquid flows on the slide surface, the flow time (t) on each block, and the upper layer thickness of two adjacent layers The maximum value of the integrated value Σ (d × t) and the integrated value Σ (d × (D1 / D2) × t) calculated from (D1) and the lower layer thickness (D2) is within a predetermined range. In the example, the grain-like unevenness and the color unevenness in the width direction were improved as compared with the comparative example. In Examples 2 and 3, the maximum value of the integrated value Σ (d × t) is 30 or less and the maximum value of the integrated value Σ (d × (D1 / D2) × t) is 25 or less. In particular, excellent results were obtained with respect to the improvement of color unevenness in the width direction. Accordingly, the smaller the maximum value of the integrated value Σ (d × t) and the maximum value of the integrated value Σ (d × (D1 / D2) × t), the more effective the grain-like unevenness and the color unevenness in the width direction. It can be predicted that it can be suppressed.

  The present invention is not limited to the configuration described in the above-described embodiment, and various modifications and changes can be made without departing from the configuration of the present invention.

1 base film, 2 back roll, 3 coater die, 4 coating solution, 5 vacuum chamber, 6 wetted part, 7, 8, 9 angle, 10 vacuum unit, 11, 11A, 11B, 11C, 11D, 11E block, 12B, 12C, 12D, 12E Slide surface, dt ₁₁ , dt ₁₂ , dt ₁₃ , dt ₂₁ , dt ₂₂ , dt ₃₁ , dt ₃₂ interface, S1, S2, S3, S4 coating liquid layer, u ₁₁ , u ₁₂ , u ₁₃ , u ₂₁ , u ₂₂ , u ₃₁ interface flow velocity

Claims (4)

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 base film using a slide hopper coating device. A method for producing an optical reflective film comprising:
The shear rate d on the high-viscosity liquid side of the velocity component parallel to the slide surface of the falling liquid film on the slide surface at each interface on each block,
When the flow time of each block at the interface is t,
The maximum value of the integrated value from the formation of the interface of (d × t) at each interface to the application is the simultaneous multilayer coating under the condition of Σ (d × t) ≦ 50. Production method.   When the falling film thickness D1 on the upper layer side at each interface and the falling film thickness D2 on the lower layer side are set, the interface between the numerical values of (d × (D1 / D2) × t) at each interface is formed and then applied. The method for producing an optical reflective film according to claim 1, wherein the simultaneous multilayer coating is performed under the condition that Σ (d × (D1 / D2) × t) ≦ 30 is the maximum integrated value.   The method for producing an optical reflective film according to claim 1 or 2, wherein a difference in viscosity between coating liquids adjacent to each interface is 100 cp or more. The method for producing an optical reflective film according to any one of claims 1 to 3, wherein the coating liquid for high refractive index layer and the coating liquid for low refractive index layer contain at least one kind of metal oxide.

Images