JP6459751B2 - Manufacturing method of optical film - Google Patents

Description

The present invention relates to the production how the optical film.

The optical film is a film that can transmit or reflect and absorb light, and refers to a film that can exhibit optical functions such as refraction, birefringence, antireflection, wide viewing angle, light diffusion, and brightness enhancement.
The optical film is an infrared shielding film, an ultraviolet shielding film, an anti-reflection film, an alignment film, a polarizing film, a polarizing plate protective film, a retardation film, a viewing angle widening film, a brightness enhancement film, an electromagnetic shielding film, etc. It is used for flat panel displays (FPD) such as LCDs and plasma displays (PDP), or window glass of buildings and vehicles.
The optical film may be used with at least two optical interference layers formed. For example, the optical film thickness of the high refractive index layer and the low refractive index layer may be adjusted and laminated on the surface of the substrate. Those having a multilayer laminated film structure are known. An optical film having a multilayer laminated film structure is known to selectively reflect light having a specific wavelength, and is used as an optical reflecting film.

The optical reflection film can control the reflection wavelength of light only by adjusting the film thickness and refractive index of each layer. Thus, the optical reflection film can selectively reflect infrared rays, ultraviolet rays, and visible light by a design according to the purpose of use.
In particular, due to the recent increase in interest in energy-saving measures, there is a demand for an infrared shielding film that can be attached to a window glass of a building or vehicle to block the transmission of solar heat rays from the viewpoint of reducing the load on cooling equipment. It is increasing.
As a method for forming an infrared shielding film, a laminated film having a structure in which a high refractive index layer and a low refractive index layer are alternately laminated is mainly formed by using a dry film forming method such as a vapor deposition method or a sputtering method. A method of forming has been proposed. However, in the dry film forming method, a vacuum apparatus or the like used for forming becomes large, the manufacturing cost is high, and it is difficult to increase the area, and the base material is limited to a heat resistant material.

A method of forming an infrared shielding film using a wet coating method instead of the dry film forming method having the above-described problems is known (for example, see Patent Document 1).
In general, as a method for producing a laminated film of two or more layers on a substrate by wet coating, there are sequential coating in which coating and drying are performed one layer at a time, and simultaneous multilayer coating in which a plurality of layers are coated simultaneously.
Sequential coating includes spin coating, bar coating, blade coating, gravure coating, and the like. However, when a multilayer film such as an optical reflection film is produced, productivity is low because the number of coating and drying increases.
On the other hand, as simultaneous multilayer coating, there is a method using curtain coating, slide bead coating, or the like, and since a plurality of layers can be formed at the same time, productivity is high, and therefore simultaneous multilayer coating is preferably employed.

In Patent Document 2, as a method for producing a laminated film by wet coating, each layer constituting the optical interference layer contains inorganic oxide fine particles and polyvinyl alcohol, and each layer constituting each layer is composed of the inorganic oxide fine particles and There has been disclosed a technique capable of providing an antireflection film having high productivity and excellent antireflection performance by containing polyvinyl alcohol having different saponification degrees.
However, as described in Patent Document 2, by containing polyvinyl alcohol having a different saponification degree from the inorganic oxide fine particles and the adjacent layer, interlayer mixing is suppressed and the film thickness can be uniformly applied, but at the start of application When the coating solution is fed into a pipe sealed with water, aggregates are formed and the aggregates flow out at the start of coating, causing a film surface failure, and improvement has been demanded.

JP 2009-86659 A JP2013-122516A

Therefore, the present invention has been made in view of the above problems and situations, and in the method of manufacturing an optical film, while maintaining high productivity, the generation of aggregates in the pipe is suppressed, and a film surface failure is caused. reduced, and to provide a manufacturing how an optical film capable of lowering the haze.

  In order to solve the above-mentioned problems, the present inventor, in the process of examining the cause of the above-mentioned problems, uses a coating liquid containing inorganic oxide fine particles and polyvinyl alcohol on at least one surface of the support. A method for producing an optical film having a step of forming an optical interference layer composed of layers of the above-mentioned polyvinyl alcohol contained in the coating solution in advance in a pipe for liquid feeding in the step When the filling liquid containing polyvinyl alcohol having a low saponification degree and a low polymerization degree is filled and then the coating liquid is introduced into the pipe, the filling liquid is discharged from the pipe to the outside, and the coating liquid The liquid is fed into the pipe, applied onto the support, and the optical interference layer is formed, thereby suppressing the generation of aggregates in the pipe while maintaining high productivity. And to reduce the film surface faults, and haze was completed the present invention found that it is possible to lower.

That is, the said subject which concerns on this invention is solved by the following means.
1. An optical film manufacturing method comprising a step of forming an optical interference layer composed of one layer or a plurality of layers using a coating liquid containing inorganic oxide fine particles and polyvinyl alcohol on at least one surface of a support. ,
In the pipe for liquid feeding in the step, a filling liquid containing polyvinyl alcohol having a lower saponification degree and a lower polymerization degree than the polyvinyl alcohol contained in the coating liquid is filled in advance, and then the coating liquid When the liquid is introduced into the pipe, the filling liquid is discharged from the pipe to the outside, and the coating liquid is fed into the pipe and applied onto the support to form the optical interference layer. The manufacturing method of the optical film characterized by the above-mentioned.

2. The optical interference layer is composed of a plurality of layers adjacent to each other and having different refractive indexes,
Each of the layers constituting the optical interference layer contains the inorganic oxide fine particles and the polyvinyl alcohol, and the polyvinyl alcohol contained in the layers adjacent to each other has different saponification degrees. 2. A method for producing an optical film according to item 1.

  3. 3. The method for producing an optical film according to claim 2, wherein the coating liquid for forming each layer constituting the optical interference layer is fed simultaneously with discharging the filling liquid to the outside of the pipe.

  4). The saponification degree of the polyvinyl alcohol contained in the filling liquid is in the range of 73 to 85 mol%. The optical film according to any one of items 1 to 3, Production method.

  5. Item 5. The method for producing an optical film according to any one of Items 1 to 4, wherein a degree of polymerization of the polyvinyl alcohol contained in the filling liquid is in a range of 300 to 2000.

  6). The said optical film is an optical reflection film, The manufacturing method of the optical film as described in any one of Claim 1-5 characterized by the above-mentioned.

  7). The method for producing an optical film according to item 6, wherein the optical reflection film is an infrared shielding film.

By the means of the present invention, while maintaining high productivity, suppressing the occurrence of agglomerates in the pipe, to reduce the film surface faults and manufacturing how the optical film capable of haze to reduce the Can be provided.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
As described above, when a coating liquid containing inorganic alcohol fine particles and containing polyvinyl alcohol having a different saponification degree from an adjacent layer is applied in multiple layers, interlayer mixing is unlikely to occur, and the film has high productivity. A surface failure sometimes occurred. From the results of the analysis, the film surface failure was caused by aggregates contained in the coating solution. The inventor has found that when the coating liquid is fed into a pipe sealed with water at the start of application, the aggregate is formed as a generation source of the aggregate.
In addition, when performing multilayer coating, the film thickness of one layer is very thin, so if the agglomerates are generated at the start of coating, not only immediately after the start of production, but also in the subsequent film thickness adjustment, many productions This is a very important problem because it takes time, sometimes the application apparatus is disassembled and cleaned, and then production is started again.
Here, the laminated optical film is obtained by adding and mixing a metal oxide, which is an aqueous dispersion, to a solution of a water-soluble resin and preparing a coating solution, followed by coating and drying. The coating solution is fed from a coating solution preparation kettle to a coating device (hereinafter also referred to as a coating coater) through a pipe and applied. By the way, when the liquid is supplied to the coating coater, the inside of the pipe is filled with water in order to suppress the mixing of bubbles and the like.
When the coating liquid is fed to the pipe filled with water in this way, not only the lamination but also the dilution of the coating liquid or the aggregation of metal oxides due to changes in liquid properties (pH, viscosity, etc.), water-soluble resin It was confirmed that the resin precipitates to form resin aggregates. It was found that these agglomerates cause film surface defects such as tailing and streaks.
Therefore, in order to avoid such a phenomenon, the inventors proceeded with an alternative study of water filled in the piping, but the filled solution is filled from the end of production until the start of production. Yes, depending on the case, it is stored stagnant in the piping for a long time. Therefore, it is required not to cause aggregation in the piping or corrosion of the piping, and it is not easy to use a filling liquid to which an additive or a resin is added.
General water-soluble resins have strong hydrogen bonding properties, network formation by hydrogen bonding proceeds at the time of long-term stagnation, and aggregation of water-soluble resins occurs. It has been very difficult to achieve both long-term stability.
As a result of investigations, the inventors have filled the pipe with a filling solution containing polyvinyl alcohol having a low saponification degree and a low degree of polymerization, thereby having long-term stability in the pipe and suppressing aggregates. It was found that no film surface defects occurred.

Schematic block diagram of an optical film manufacturing system that can be used as one embodiment

The method for producing an optical film of the present invention includes a step of forming an optical interference layer composed of one layer or a plurality of layers using a coating liquid containing inorganic oxide fine particles and polyvinyl alcohol on at least one surface of a support. A method for producing an optical film comprising: a polyvinyl alcohol having a lower saponification degree and a lower polymerization degree than the polyvinyl alcohol contained in the coating liquid in advance in a pipe for liquid feeding in the step. When filling the filling liquid and then introducing the coating liquid into the pipe, the filling liquid is discharged from the pipe to the outside, and the coating liquid is fed into the pipe, And the optical interference layer is formed.
This feature is a technical feature common to the invention according to the present embodiment .

As an embodiment of the present invention, from the viewpoint of manifestation of the effect of the present invention, the optical interference layer is composed of a plurality of layers adjacent to each other and having different refractive indexes, and each layer constituting the optical interference layer is the inorganic oxide. It is preferable that the polyvinyl alcohols containing the fine particles and the polyvinyl alcohol, and contained in the layers adjacent to each other, have different saponification degrees.
In addition, by discharging the filling liquid to the outside of the pipe and simultaneously feeding the coating liquid that forms each layer constituting the optical interference layer, it is possible to prevent bubble entrainment at the time of feeding the coating liquid and reduce the film surface failure. From the viewpoint of
Moreover, it is preferable from a viewpoint of aggregation suppression that the saponification degree of the said polyvinyl alcohol contained in the said filling liquid exists in the range of 73-85 mol%.
Moreover, it is preferable from a haze viewpoint that the polymerization degree of the said polyvinyl alcohol contained in the said filling liquid exists in the range of 300-2000.
Moreover, it is preferable as embodiment that the said optical film is an optical reflection film.
Moreover, it is preferable that the said optical reflection film is an infrared rays shielding film from a viewpoint of an effect expression.
In addition, it is preferable to use an optical film manufactured by the manufacturing method described in any one of the above items, and that the optical film is an optical film laminate provided on at least one surface of the substrate. Preferred from the viewpoint of expression.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, "-" shown in this invention is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<< Optical film manufacturing method >>
Although it demonstrates in FIG. 1 which is one form of this invention, it is not limited to this.
As shown in FIG. 1, the manufacturing process consists of a preparation process, a circulation process, and a coating process. In the pipe for liquid feeding in the manufacturing process, the saponification is lower than that of polyvinyl alcohol contained in the coating liquid in advance. When filling the filling liquid containing polyvinyl alcohol having a degree of polymerization and a low polymerization degree and introducing the coating liquid into the pipe, the filling liquid is discharged from the pipe to the outside, and the coating liquid is fed into the pipe. Then, the optical interference layer is formed.

<Preparation of filling liquid filled in piping>
In the present invention, the filling liquid to be filled in the pipe is prepared using polyvinyl alcohol having a low saponification degree and a low polymerization degree as described below. This is preferable from the viewpoint of suppressing aggregation.
The preparation method is not particularly limited, and examples thereof include a method in which polyvinyl alcohol having a low saponification degree and a low polymerization degree is added and stirred.
The content of polyvinyl alcohol having a low saponification degree and a low polymerization degree in the filling liquid is within a range of 1 to 15% by mass with respect to the total mass (solid content), and the long-term stability and discharge of the filling liquid From the viewpoint of sex. The prepared filling liquid containing polyvinyl alcohol having a low saponification degree and a low polymerization degree is filled in the pipe.

(Polyvinyl alcohol with low saponification degree and low polymerization degree)
As the low saponification degree and low polymerization degree polyvinyl alcohol used in the present invention, a synthetic product or a commercially available product may be used. Examples of commercially available products used as polyvinyl alcohol include, for example, PVA-403, PVA-405, PVA-420, L-9-78, L-10, PVA-505 (all manufactured by Kuraray Co., Ltd.), JL- 05E, JL-18E (above, manufactured by Nippon Vinegar Poval Co., Ltd.), W20N (produced by Denki Kagaku Kogyo Co., Ltd.), KH-20, KH-17, KL-05, KL-03 (above, Nippon Synthetic Chemical Industry) Etc.).

  The saponification degree of polyvinyl alcohol is preferably in the range of 73 to 85 mol%, and more preferably in the range of 75 to 83 mol%. If the saponification degree is 73 mol% or more, the solubility of polyvinyl alcohol in water does not decrease, and self-aggregation between resins is suppressed even if the pipe is filled in the pipe for a long time. When the saponification degree is 85 mol% or less, the occurrence of aggregation due to mixing with the coating liquid to be fed can be suppressed.

As used herein, “degree of saponification” refers to the rate at which an acetyloxy group (also referred to as “acetic acid group”) contained in a polyvinyl acetate resin, which is a raw material for polyvinyl alcohol, has been changed to a hydroxy group by a saponification step. Is expressed as a unit ratio (mol%), which is a numerical value defined by the following formula.
Saponification degree (mol%) = (number of hydroxy groups) ÷ (number of hydroxy groups + number of acetyloxy groups) × 100
The degree of saponification can be determined by a method defined in JIS K 6726 (1994). When the degree of saponification of polyvinyl alcohol is not limited to one value but has a width (distribution), “degree of saponification” means an average value of the degree of saponification of polyvinyl alcohol.

The polymerization degree of polyvinyl alcohol is preferably in the range of 300 to 2000, and more preferably in the range of 500 to 1500. If the degree of polymerization is 300 or more, aggregates due to mixing with the coating solution are suppressed, and if the degree of polymerization is 2000 or less, self-aggregation between resins is suppressed.
In the present specification, the degree of polymerization of polyvinyl alcohol means the degree of polymerization measured according to JIS K6726: 1994.

(solvent)
Although it does not restrict | limit especially as a solvent, Water, an organic solvent, or its mixed solvent etc. are mentioned.
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; ketones such as acetone, methyl ethyl ketone, acetylacetone and cyclohexanone. These organic solvents may be used alone or in admixture of two or more.
From the viewpoint of environment and simplicity of operation, the solvent of the coating solution is preferably water or a mixed solvent of water and methanol, ethanol, or ethyl acetate, and more preferably water.

<Preparation process of coating solution>
Next, a method for preparing a coating solution for forming the optical interference layer will be described.
The method for preparing the coating liquid is not particularly limited, and examples thereof include a method in which a material having a desired function is added and stirred and mixed. At this time, the order of addition of the respective components is not particularly limited, and the respective components may be sequentially added and mixed while stirring, or may be added and mixed at one time while stirring. If necessary, it is adjusted to an appropriate viscosity using a solvent.
In the following description, a method for producing an optical reflection film in which refractive index layers having different refractive indexes are laminated, particularly an infrared shielding film, will be described, but the present invention is not limited thereto. The optical reflection film corresponds to an optical film, and the refractive index layer corresponds to an optical interference layer.

As the coating liquid applied simultaneously with the multilayer, the coating liquid for forming the high refractive index layer and the low refractive index layer constituting the optical reflection film (hereinafter referred to as “high refractive index layer coating liquid” and “low refractive index layer coating”). (Also referred to as “liquid”).
As the coating solution, in addition, a coating solution for a medium refractive index layer having an intermediate refractive index between a high refractive index layer and a low refractive index layer; a coating solution for a low viscosity slip layer for facilitating coating; Examples thereof include a low surface tension coating solution that can be used for the uppermost layer in order to suppress contraction of the coating solution on the slide surface.
The coating solution for each refractive index layer preferably contains inorganic oxide particles, a polymer, a crosslinking component, and other additives and solvents added as necessary. 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.
Hereinafter, each component which comprises a coating liquid is explained in full detail.

(Polyvinyl alcohol)
In the present invention, there is an optical interference layer on at least one surface of the support, and the layer included in the optical interference layer is formed by applying a coating solution containing inorganic oxide fine particles and polyvinyl alcohol. Is preferred. Further, the optical interference layer is composed of a plurality of layers adjacent to each other and having different refractive indexes, and each of the layers constituting the optical interference layer contains inorganic oxide fine particles and polyvinyl alcohol, and is adjacent to each other. It is more preferable that the contained polyvinyl alcohols have different saponification degrees. In particular, in the case of multilayer coating, the inclusion of polyvinyl alcohols having different saponification degrees suppresses interlayer mixing during coating and drying. it can.

As the polyvinyl alcohol used in the present invention, a synthetic product or a commercially available product may be used. Examples of commercially available products used as polyvinyl alcohol 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 (manufactured by Kuraray Co., Ltd.), JC-25, JC-33, JF-03, JF- 04, JF-05, JP-03, JP-04, JP-05, JP-45 (manufactured by Nippon Vinegar Poval Co., Ltd.) and the like.
The polyvinyl alcohol preferably used 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.

As the polyvinyl alcohol obtained by hydrolysis of vinyl acetate, those having a polymerization degree of 1000 or more are preferably used, and those having a polymerization degree in the range of 1,500 to 5,000 are particularly preferably used.
The degree of saponification is preferably in the range of 80 to 100 mol%, particularly preferably in the range of 85 to 99.5 mol%. Within such a range, the solubility in water is good and the film defects after coating are reduced.

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, hydroxyethyltrimethylammonium 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 in the range of 0.1 to 10 mol%, preferably in the range of 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 copolymer of vinyl compound having hydrophobic group and vinyl alcohol, silanol-modified polyvinyl alcohol having silanol group, reactive group modification having reactive group such as acetoacetyl group, carbonyl group and carboxy group Polyvinyl alcohol etc. are mentioned. Examples of the vinyl alcohol-based polymer include EXEVAL (trade name: manufactured by Kuraray Co., Ltd.) and Nichigo G polymer (trade name: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).
Polyvinyl alcohol can be used in combination of two or more, such as the degree of polymerization and the type of modification. When two or more types are used, they may be added separately.

  The weight average molecular weight of polyvinyl alcohol is preferably in the range of 1,000 to 200,000 or more. Furthermore, the range of 3,000 to 40,000 is more preferable. The weight average molecular weight can be measured, for example, using gel permeation chromatography (GPC) under the following measurement conditions.

  In the present invention, each layer preferably contains polyvinyl alcohol having a saponification degree different from that of the adjacent layer. As one embodiment, a form in which units containing a refractive index layer containing polyvinyl alcohol having a high degree of saponification and a refractive index layer containing polyvinyl alcohol having a low degree of saponification are alternately laminated can be mentioned.

In the present invention, the difference in the absolute value of the saponification degree of polyvinyl alcohol contained in two adjacent layers is preferably 2 mol% or more, more preferably 5 mol% from the viewpoint of the antireflection performance of the antireflection film. That's it.
If at least one layer constituting the optical interference layer has a difference in the degree of saponification from the polyvinyl alcohol contained in the adjacent layer within the above preferable range, the antireflection performance is improved, but more preferably, the antireflection is achieved. It is preferable that the difference in the saponification degree of all the layers constituting the film with the polyvinyl alcohol contained in the adjacent layer is within the above-mentioned preferable range. The difference in the degree of saponification of the polyvinyl alcohol contained in the two adjacent layers is preferably as far as they are apart, but it is preferably 20 mol% or less from the viewpoint of the solubility of polyvinyl alcohol in water.
In the present invention, each layer may contain a plurality of polyvinyl alcohols having different saponification degrees. In this case, the difference in the saponification degree is determined by the saponification of polyvinyl alcohol (PVA) of each obtained refractive index layer. The degree of conversion can be calculated by dissolving in dimethyl sulfoxide-d6 (DMSO-d6), measuring by NMR, and determining the difference between the two.
The content of polyvinyl alcohol contained in each layer is preferably in the range of 20 to 80% by mass and more preferably in the range of 25 to 75% by mass with respect to the total mass (solid content) of each layer. preferable.

(Inorganic oxide particles)
Inorganic oxide particles include Li, Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Nb, Zr, and Mo. 1 or 2 selected from the group consisting of Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ta, Hf, W, Ir, Tl, Pb, Bi and rare earth metals, and silicon (Si) The above inorganic oxides can be used.

The inorganic oxide particles preferably have an average particle size in the order of 100 nm or less, preferably in the range of 4 to 50 nm, and more preferably in the range of 4 to 30 nm.
Here, the average particle diameter refers to the primary average particle diameter. The average particle diameter of the inorganic oxide particles is when the inorganic oxide particles are coated (for example, silica-attached titanium oxide), and the average particle diameter of the inorganic oxide particles is the base (in the case of silica-attached titanium oxide) , Titanium oxide before treatment).

In the coating solution for the low refractive index layer, it is preferable to use silicon oxide (silica, SiO ₂ ) as the inorganic oxide particles.
Here, examples of the silicon oxide include synthetic amorphous silica and colloidal silica. Colloidal silica can be obtained by heating and aging a silica sol obtained by metathesis using an acid of sodium silicate or the like and passing through an ion exchange resin layer. Such colloidal silicas are disclosed in, for example, JP-A-57-14091, JP-A-60-219083, JP-A-60-219084, JP-A-61-20792, JP-A-61- No. 188183, JP-A-63-17807, JP-A-4-93284, JP-A-5-278324, JP-A-6-92011, JP-A-6-183134, JP-A-6-297830 No. 7, JP-A-7-81214, JP-A-7-101142, JP-A-7-179029, JP-A-7-137431, and International Publication No. 94/26530. . Such silicon oxide (SiO ₂ ) is also commercially available. Examples of commercially available colloidal silica include Snowtex (registered trademark) OXS (manufactured by Nissan Chemical Industries, Ltd.).

Examples of the inorganic oxide contained in the coating solution for the high refractive index layer include titanium oxide, zinc oxide, aluminum oxide (alumina), zirconium oxide, hafnium oxide, niobium oxide, tantalum oxide, magnesium oxide, barium oxide, and oxide. Particles and composite particles of indium, tin oxide, lead oxide, lithium niobate, potassium niobate, lithium tantalate, aluminum / magnesium oxide (MgAl ₂ O ₄ ), etc., which are complex oxides composed of these oxides Can be mentioned. In order to form a transparent and higher refractive index layer having a higher refractive index, it is preferably a high refractive index inorganic oxide fine particle such as titanium or zirconia, that is, a titanium oxide fine particle or a zirconia oxide fine particle. ) Titanium dioxide particles are more preferred.
Further, as the titanium oxide particles, those obtained by modifying the surface of an aqueous titanium oxide sol to stabilize the dispersion state, as described in International Publication No. 2013-054912, the titanium oxide particles are hydrated oxides containing silicon. The core-shell particles manufactured by a known method may be used. Examples of the titanium oxide particles coated with a silicon-containing hydrated oxide include silica-attached titanium dioxide sol in which SiO ₂ is attached to the surface of rutile-type titanium dioxide particles.

The concentration of the inorganic oxide particles in the coating solution is not limited, but is preferably in the range of 1 to 15% by mass, more preferably in the range of 2 to 10% by mass in terms of solid content. preferable.
A content of inorganic oxide particles of 1% by mass or more is preferable because a desired refractive index can be obtained. Moreover, it is preferable that the content of the inorganic oxide particles is 15% by mass or less because flexibility of the film can be obtained and film formation becomes easy.
The content of the inorganic oxide particles in the optical interference layer is preferably in the range of 20 to 90% by mass and preferably in the range of 35 to 80% by mass with respect to the entire optical interference layer. More preferred. When the content of the inorganic oxide particles is in the above range, it is preferable because the light reflection efficiency of the optical film is improved.

(Other additives)
Examples of other additives include ultraviolet absorbers, anions, cations, and nonions described in JP-A-57-74193, JP-A-57-87988, JP-A-62-261476, and the like. Various surfactants, sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and other pH adjusters, antifoaming agents, diethylene glycol and other lubricants, antiseptics, antifungal agents, electrification Examples include various known additives such as an inhibitor, a matting agent, an antioxidant, a flame retardant, an infrared absorber, a dye, a pigment, an emulsion resin, a viscosity modifier, and a thixotropic agent. Further, those addition amounts can be appropriately determined by those skilled in the art, and mixing can also be performed by referring to or combining conventionally known knowledge.
Here, citric acid functions as a pH adjuster. In addition, it is preferable that the density | concentration of the citric acid in a coating liquid exists in the range of 0.01-2 mass% in conversion of solid content. When the citric acid is within the above range, it is preferable from the viewpoint of ensuring stability in the liquid of the polymer and the metal oxide and suppressing aggregation.

(solvent)
Although it does not restrict | limit especially as a solvent, Water, an organic solvent, or its mixed solvent etc. are mentioned.
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; ketones such as acetone, methyl ethyl ketone, acetylacetone and cyclohexanone. These organic solvents may be used alone or in admixture of two or more.
From the viewpoint of environment and simplicity of operation, the solvent of the coating solution is preferably water or a mixed solvent of water and methanol, ethanol, or ethyl acetate, and more preferably water.

<Application method>
The coating method of the coating solution for forming the optical interference layer is not particularly limited, and, for example, US Pat. Nos. 2,761,419 and 2,761,791 as long as the simultaneous multilayer coating method is used. The slide bead coating method using the hopper described in the above, the extrusion coating method and the like are preferably used.
The coating and drying methods for simultaneous multilayer coating are as follows. The coating liquid for forming each optical interference layer is heated to 30 to 60 ° C., and the simultaneous multilayer coating of the coating liquid for forming each optical interference layer on the substrate is performed. The temperature of the formed coating film is preferably once cooled (set) to 1 to 15 ° C. and then dried at 10 ° C. or higher. More preferable drying conditions are a wet bulb temperature of 5 to 50 ° C. and a film surface temperature of 10 to 50 ° C. For example, it is dried by blowing warm air of 80 ° C. for 1 to 5 seconds. Further, as a cooling method immediately after coating, it is preferable to carry out a horizontal setting method from the viewpoint of improving the uniformity of the formed coating film.

In the manufacturing method according to an embodiment of the present embodiment, the coating speed is 10 m / min or more, preferably 30 m / min or more. According to the manufacturing method of the present invention, even at such a high speed, it is possible to obtain a multilayer laminated film with improved uniformity of film thickness and reduced interference unevenness.
Each optical interference layer may be applied so as to have a preferable dry thickness.
As a drying method, warm air drying, infrared drying, and microwave drying are used. Also, 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 decreasing rate drying section. In this case, the temperature range of the constant rate drying section is preferably in the range of 30 to 60 ° C., and the temperature range of the decreasing rate drying section is preferably in the range of 50 to 100 ° C.

Here, the set is to increase the viscosity of the coating composition by means of lowering the temperature by applying cold air or the like to the coating film, or reducing the fluidity of the substances in each layer and in each layer, or It means the 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. The lower limit time is not particularly limited, but it is preferable to take a time of 10 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 layer forming component proceeds, and there is a possibility that the function manifestation of each optical interference layer becomes insufficient. For example, when the optical interference layer has a structure in which a high refractive index layer and a low refractive index layer are alternately stacked, the refractive index difference may be insufficient.

<Base material>
The base material applied to the optical film is not particularly limited as long as it is transparent, and a known resin film can be used. Specifically, polyethylene, polypropylene, polystyrene, polyarylate, polymethyl methacrylate, polyamide, polycarbonate, polyethylene terephthalate (hereinafter also referred to as PET), polybutylene terephthalate, polyethylene naphthalate (hereinafter also referred to as PEN), polysulfone, Examples of the resin film include polyethersulfone, polyetheretherketone, polyimide, aromatic polyamide, and polyetherimide. Among these, it is preferable to use resin films such as polyethylene terephthalate, polyethylene naphthalate, and polycarbonate from the viewpoint of cost and availability.
Further, the substrate using the resin film may be an unstretched film or a stretched film, but in the case of a resin film having crystallinity such as PET or PEN, the strength is improved. From the viewpoint of suppressing thermal expansion, a film that is heat-set after stretching is preferred.
The thickness of the substrate is preferably in the range of 5 to 300 μm, and more preferably in the range of 15 to 150 μm. In addition, the base material may be a laminate of two or more, and in this case, the type of the base material may be the same or different.

The base material may be provided with an undercoat layer on one side or both sides in the film forming process.
The undercoat layer can be formed in-line or after film formation. Examples of the method for forming the undercoat layer include a method of applying an undercoat layer coating solution and drying the obtained coating film. As the undercoat layer, a known layer can be used, and it may have a single layer structure or a laminated structure.

Substrate is further conductive layer, antistatic layer, gas barrier layer, easy adhesion layer (adhesion layer), antifouling layer, deodorant layer, flow drop layer, easy slip layer, hard coat layer, wear resistant layer, You may have well-known interference layers, such as an adhesion layer and an intermediate film layer. These may be formed on both sides.
When the base material has an intermediate layer such as the undercoat layer or the interference layer, the total film thickness of the base material and the intermediate layer is preferably in the range of 5 to 500 μm, and in the range of 25 to 250 μm. More preferably, it is within.

<Optical film manufacturing system>
Next, an example of a suitable manufacturing system used in the manufacturing method according to an embodiment of the present invention will be described.
FIG. 1 is a schematic configuration diagram illustrating an example of an optical film manufacturing system according to an embodiment of the present invention.
An optical film manufacturing system 100 shown in FIG. 1 is configured by connecting a plurality of devices, and manufactures an optical film through a plurality of steps realized by each device. In the example illustrated in FIG. 1, the optical film manufacturing system 100 includes a preparation process, a circulation process, and a coating process.

(Preparation of filling liquid containing polyvinyl alcohol with low saponification degree and low polymerization degree and filling of pipes)
The preparation kettle 101 is a container for preparing a filling liquid and a coating liquid containing polyvinyl alcohol having a low saponification degree and a low polymerization degree. The method for preparing the filling liquid containing polyvinyl alcohol having a low saponification degree and a low polymerization degree is not particularly limited, and is a method in which polyvinyl alcohol having a low saponification degree and a low polymerization degree is added to a solvent and stirred.
The filling liquid prepared in the preparation pot 101 is supplied from the preparation pot in FIG. 1 to the pipes up to the coating apparatus 110 including the circulation path R1 and the supply path L1 using the liquid feeding devices 102, 105, and 109. Filling is preferred. Here, in this case, the filling liquid may be filled not only in the piping between the apparatuses but also in the apparatus.

(Discharge of filling liquid containing polyvinyl alcohol with low saponification degree and low polymerization degree and feeding of coating liquid)
The filling liquid filled in the pipe is discharged from the pipe to the outside when the coating liquid prepared in the preparation pot 101 described below is introduced into the pipe, and the coating liquid is transferred to the next process. The liquid is sent.
In the present application, “to discharge the filling liquid from the inside of the pipe and send the coating liquid into the pipe” means that the coating liquid is sent (sequentially) after the filling liquid is completely discharged; Both the case where the coating liquid is fed simultaneously with the discharge are included. In particular, it is preferable to discharge the filling liquid and simultaneously feed the coating liquid from the viewpoint of preventing entrainment of bubbles.

(Preparation process of coating solution)
The method for preparing the coating solution is not particularly limited, and is a method in which a component that forms an optical interference layer, for example, polyvinyl alcohol, metal oxide particles, and the like are added to a solvent and mixed by stirring. 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 these coating solutions is appropriately determined for each coating solution.
The preparation pot 101 is connected to the storage pot 104 in order to supply the coating liquid to the storage pot 104 included in the circulation process.
The liquid feeding device 102 is provided in a path for feeding the coating liquid from the preparation pot 101. The liquid feeding device 102 is, for example, a pump, and can control feeding of the prepared coating liquid and stopping of the liquid feeding. The liquid feeding device 102 can appropriately set the flow rate and speed of the coating liquid when feeding the coating liquid. For example, the liquid delivery device 102 delivers the coating liquid simultaneously with the discharge of the filling liquid.
The filtration device 103 is provided in a path for feeding the coating liquid from the preparation kettle 101. The filtration device 103 removes foreign matters mixed in the coating liquid, and foreign matters due to bubbles or aggregation generated in the coating liquid. The coating liquid from which the foreign matter has been removed is sent to a circulation process.

(Circulation process)
The optical film manufacturing system 100 is circulated in the circulation process (coating liquid circulation system) for preventing aggregation of the prepared coating liquid. The circulation process includes a storage tank 104, a liquid feeding device 105, a dispersion device 106, a defoaming device 107, a filtration device 108, and a circulation path R1.
The storage pot 104 stores the coating liquid so that the coating liquid can be continuously supplied. The storage pot 104 is preferably provided with a stirring device for circulating the coating liquid even inside the storage pot 104. Thereby, the physical property of the coating liquid in the storage pot 104 can be made uniform. A circulation path R <b> 1 is connected to the storage tank 104 for discharging the filling liquid and simultaneously feeding the coating liquid from the storage tank 104 and returning the coating liquid to the storage tank 104 again. The storage tank 104 is also connected to a supply path for sending the coating liquid to the supply process and the application process.

The liquid feeding device 105 is provided on the circulation path R1. The liquid feeding device 105 is, for example, a pump, and can control feeding of the coating liquid stored in the storage pot 104 and stopping of the liquid feeding. The liquid feeding device 105 can appropriately set the flow rate and speed of the coating liquid when feeding the coating liquid.
The dispersion device 106 is provided on the circulation path R1. The dispersion device 106 performs a dispersion process on the coating liquid, preferably a dispersion process using a shearing force. As the dispersing device 106, an emulsifying disperser, a pressure homogenizer, a high-speed rotational shearing type homogenizer, or the like can be used. As the emulsifier / disperser, for example, Ebara Milder (manufactured by Ebara Manufacturing Co., Ltd.), Milder (manufactured by Taihei Kiko Co., Ltd.), or the like can be used. As the pressure type homogenizer, for example, a pressure type homogenizer LAB1000 (manufactured by SMT Co., Ltd.) or the like can be used.
The defoaming device 107 removes bubbles contained in the coating liquid and dissolved air dissolved in the coating liquid. As a principle of defoaming, 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, as long as defoaming can be performed, the defoaming device 107 may be a device using any other principle.
The filtering device 108 removes foreign matters mixed in the coating liquid, and foreign matters due to bubbles or aggregation generated in the coating liquid. The coating liquid from which the foreign matter has been removed returns to the storage pot 104 through the circulation path R1.

As described above, in the circulation step, the coating liquid is sent from the storage tank 104 to the circulation path R1, subjected to treatment by the dispersing device 106, the defoaming device 107, and the filtration device 108, and then returned to the storage tank 104. . The coating liquid returned to the storage pot 104 may move while being stirred in the storage pot 104, and then sent again to the circulation path R1, and the above processing may be repeated.
The processing strength of the dispersion device 106, the defoaming device 107, and the filtration device 108 in the circulation process is such that the physical properties of the coating liquid are maintained within an appropriate range according to conditions such as the use of the optical film and the properties of the coating liquid used. Can be set as appropriate.
The coating liquid stored in the storage tank 104 is discharged from the supply path L1 connected to the storage tank 104, and is fed to the coating process.

In FIG. 1, the devices are arranged in the order of the dispersing device 106, the defoaming device 107, and the filtering device 108 on the circulation path R1. However, the order of these devices can be changed as appropriate. In addition, one device integrating the functions of a plurality of the above devices may be provided for the circulation process. For example, a dispersion defoaming device in which the functions of the dispersion device 106 and the defoaming device 107 are integrated may be provided in the circulation process. In addition, a device other than the above may be provided in the circulation process, or any of the above devices may not be provided.
The upper limit of the number of repetitions of the circulation process is not particularly limited, but it is preferably 4 times or less in consideration of saturation of the effect and productivity. The flow rate of the coating liquid in the circulation step is preferably 5 L / min or more from the viewpoint of the liquid storage amount.

(Coating process)
Next, the prepared and circulated coating liquid is supplied to the supply path L <b> 1 connected to the storage tank 104, for example, at the same time as the filling liquid is discharged, and supplied to the coating apparatus 110.
The liquid feeding device 109 sends the coating liquid fed from the storage tank 104 in the circulation process to each device provided in the supply path L1. The liquid feeding device 109 is, for example, a pump, and can control feeding of the prepared coating liquid and stopping of the liquid feeding. The liquid feeding device 109 can appropriately set the flow rate and speed of the coating liquid when feeding the coating liquid.
In the coating process, the optical film manufacturing system 100 applies a coating solution to a substrate to generate a polymer film. The coating process includes a coating device 110, a setting device 111, and a drying device 112.
The coating device 110 applies a coating solution to a substrate. In the case where a plurality of coating liquids are applied to a base material in multiple layers (so-called multilayer coating), at least the adjacent coating liquids are prepared with different distributions and materials. Accordingly, FIG. 1 shows one preparation pot 101, but actually, a plurality of preparation pots are prepared, and a plurality of types of coating liquids are supplied to the coating apparatus 110 through separate preparation steps and supply steps. .
In the coating step, it is preferable to apply the coating liquid onto the substrate that is continuously conveyed.

In the embodiment of the present invention, the circulation process is described as being provided in the optical film manufacturing system 100, but the present invention is not limited to this. A plurality of circulation processes may be provided in the optical film manufacturing system 100.
In the optical film manufacturing system 100, the circulation path R1 and the supply path L1 are connected as separate paths to the storage tank 104 in the circulation process, and a liquid feeding device, a dispersion device, and the like are provided in each path. Yes. However, the circulation route R1 and the supply route L1 may share a part of the route and the apparatus, and the equipment in one route may be omitted. That is, the supply path L1 may be connected in the middle of the circulation path R1, and a part of the path and the apparatus on the supply path L1 may be omitted.

<Optical film>
The structure of the optical film that can be produced in the present invention is not particularly limited as long as at least one optical interference layer is formed on the substrate.
In a preferred embodiment of the present invention, each optical functional layer of the optical film includes a high refractive index layer and a low refractive index layer, and has an optical structure in which the high refractive index layer and the low refractive index layer are alternately laminated. It is a manufacturing method of a film. 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.
As an optical film which has the said structure, an optical reflection film is mentioned, for example.
One preferable embodiment of the present invention is a method for producing an optical reflective film, wherein the optical film is an optical reflective film.

Moreover, the preferable one form of this invention is a manufacturing method of the optical reflection film whose optical reflection film is an infrared shielding film.
The optical reflection film has such a configuration, and can appropriately reflect light having a specific wavelength by appropriately controlling the optical film thickness (film thickness × refractive index) of the high refractive index layer and the low refractive index layer. . Thereby, for example, when the optical reflection film reflects light rays (ultraviolet rays) within a wavelength range of 200 to 400 nm, the optical reflection film becomes an ultraviolet shielding film and reflects light rays (visible light) within a wavelength range of 400 to 700 nm. It becomes a visible light colored film, and when it reflects light rays (infrared rays) within a wavelength range of 700 to 1200 nm, it can be an infrared shielding film. In addition, by appropriately designing the optical film thickness and the like 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 in the ultraviolet to infrared region within the wavelength range of 200 nm to 1000 μm, and more preferably a light ray having a wavelength in the range of 250 to 2500 nm. Preferably, it is a light ray in the near infrared region within a wavelength range of 700 to 1200 nm.
In general, in an optical reflection film, a design that increases the difference in refractive index between a low refractive index layer and a high refractive index layer can increase the reflectance in a desired wavelength region with a small number of layers. It is preferable from the viewpoint.

In the optical reflective 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 or more. More preferably, it is 0.3 or more, More preferably, it is 0.35 or more, Especially preferably, it is 0.4 or more. When the optical reflective 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 may be within the preferred range. preferable. However, regarding the outermost layer and the lowermost layer, a configuration outside the above preferred range may be used.
As described above, whether the layer is a high refractive index layer or a low refractive index layer is a relative one determined by the relationship with the adjacent refractive index layer, but the refractive index (nH) of the high refractive index layer is 1. It is preferably .60 to 2.50, more preferably 1.70 to 2.50, further preferably 1.80 to 2.20, and 1.90 to 2.20. Is particularly preferred. On the other hand, the refractive index (nL) of the low refractive index layer is preferably 1.10 to 1.60, more preferably 1.30 to 1.55, and 1.30 to 1.50. More preferably.

In the present invention, the refractive indexes of the high refractive index layer and the low refractive index layer can be determined, for example, according to the following method.
A sample in which each refractive index layer for measuring a refractive index is coated as a single layer on a substrate is prepared, and the sample is cut into 10 cm × 10 cm, and then the refractive index is obtained according to the following method. Using a U-4000 type (manufactured by Hitachi, Ltd.) as a spectrophotometer, after roughening the back side on the measurement side of each sample, light absorption treatment is performed with a black spray to reduce the light on the back side. The reflection is prevented, the reflectance in the visible light region (in the range of 400 to 700 nm) is measured at 25 points under the condition of regular reflection at 5 degrees, the average value is obtained, and the average refractive index is obtained from the measurement result.
The reflectance in the specific wavelength region is determined by the difference in refractive index between two adjacent layers and the number of stacked layers, and the larger the difference in refractive index, the same reflectance can be obtained with a smaller number of layers. The refractive index difference and the required number of layers can be calculated using commercially available optical design software. For example, when the optical reflection film is an infrared shielding film, 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 laminate more than 100 layers, resulting in productivity. Not only decreases, but also scattering at the laminated interface increases, transparency decreases, 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.

  From the above viewpoint, the number of layers of the high refractive index layer and the low refractive index layer of the optical reflective film according to the present invention is preferably 100 or less, that is, 50 units or less, more preferably. Is 40 layers (20 units) or less, more preferably 30 layers (15 units) or less. In addition, the optical reflective film of the present invention may have a configuration in which at least one of the above units is laminated, for example, a laminated film in which both the outermost layer and the lowermost layer of the laminated film are high refractive index layers or low refractive index layers. It may be. The optical reflective film according to the present invention preferably has a layer structure in which the lowermost layer adjacent to the substrate is a low refractive index layer and the outermost layer is also a low refractive index layer.

The total thickness of the optical reflective film according to the present invention is preferably in the range of 12 to 315 μm, more preferably in the range of 15 to 200 μm, and still more preferably in the range of 20 to 100 μm. Further, the thickness per layer of the low refractive index layer is preferably in the range of 20 to 800 nm, and more preferably in the range of 50 to 350 nm. On the other hand, the thickness per layer of the high refractive index layer is preferably in the range of 20 to 800 nm, and more preferably in the range of 50 to 350 nm.
Furthermore, as an optical characteristic of the light reflecting film according to the present invention, the transmittance in the visible light region shown in JIS R3106: 1998 is preferably 50% or more, more preferably 75% or more, and still more preferably 85% or more. Moreover, it is preferable to have a region having a reflectance exceeding 50% in a region within the light wavelength range of 900 to 1400 nm.

The optical film according to the present invention is a conductive layer, an antistatic layer, a gas barrier layer, an easy adhesion layer for the purpose of adding further functions under the base material or on the outermost surface layer opposite to the base material. (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, fluorescence Light emitting layer, hologram layer, release layer, adhesive layer, adhesive layer, infrared cut layer (metal layer, liquid crystal layer), colored layer (visible light absorbing layer) other than the high refractive index layer and low refractive index layer of the present invention, combined One or more functional layers such as an intermediate film layer used for glass may be included.
One preferable embodiment of the present invention is an optical film manufactured by the method for manufacturing an optical film.

<Application>
One preferable embodiment of the present invention is an optical film laminate in which an optical film is provided on at least one surface of a substrate. In particular, the optical film is preferably an optical reflector that is an optical reflecting film, particularly an infrared shielding body that is an infrared shielding film.
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 two or more of these may be used in combination.
The substrate that can be used in one embodiment of the present invention can be produced by a known method such as extrusion molding, calender molding, injection molding, hollow molding, compression molding or the like. The thickness of the substrate is not particularly limited, but is usually in the range of 0.1 mm to 5 cm.

When the optical film is an optical reflection film, it is preferable that the adhesive layer or the adhesive layer that bonds the optical reflection film and the substrate is disposed on the incident surface side of the optical reflection film (for example, sunlight, heat rays, etc.).
Further, it is preferable to sandwich an infrared shielding film, which is a kind of optical film according to an embodiment of 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 an infrared shielding film, which is a kind of optical reflecting film according to an embodiment of the present invention, is installed outdoors or on the outside of a vehicle (for external application), it is preferable because of environmental durability.
As an adhesive applicable to one embodiment of the present invention, an adhesive mainly composed of a photocurable or thermosetting resin can be used.
The adhesive preferably has durability against ultraviolet rays, and is preferably an acrylic pressure-sensitive adhesive or a silicone pressure-sensitive adhesive. Furthermore, an acrylic adhesive is preferable from the viewpoint of adhesive properties and cost. In particular, a solvent system is preferable in the acrylic pressure-sensitive adhesive because the peel strength can be easily controlled. When a solution polymerization polymer is used as the acrylic solvent-based pressure-sensitive adhesive, known monomers can be used as the monomer.

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

Insulation performance and solar heat shielding performance of an optical reflecting body (infrared shielding body) which is one type of optical film or an optical film laminate is generally JIS R3209 (multi-layer glass), JIS. R3106 (Test method for transmittance, reflectance, emissivity, and solar heat gain of sheet glass) and JIS R3107 (Calculation method for thermal resistance of sheet glass and thermal conductivity in buildings) .
Measurements of solar transmittance, solar reflectance, emissivity, and visible light transmittance are as follows: (1) Spectral photometer with wavelength (within 300 to 2500 nm), spectral transmittance and spectral reflectance of various single plate glasses Measure. Further, the emissivity is measured using a spectrophotometer within a wavelength range 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 in accordance with JIS R3106 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 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 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 obtained according to JIS R3107. (2) Heat insulation, heat transfer resistance is added to the thermal resistance of the multi-layer glass, and the heat flow resistance is obtained. (3) The solar heat shielding property is calculated by obtaining the solar heat acquisition rate according to JIS R3106 and subtracting it from 1.

  Moreover, since the infrared shielding film obtained above is a thin film, it may be applied to the surface of a display panel. For example, in a plasma display panel, an infrared shielding film can be bonded to a highly transparent PET film and introduced into a display screen. As a result, infrared rays radiated from the plasma display panel can be shielded, contributing to protection of the human body, prevention of malfunction between electronic devices, prevention of malfunction of the remote control, and the like.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples. EXAMPLES The present invention will be specifically described with reference to examples, but the present invention is not limited to these.
Unless otherwise specified, measurements such as operation and physical properties are performed under conditions of room temperature (23 ° C.) / 55% relative humidity, and “%” and “part” are “mass%” and “part by mass”, respectively. means.

(Preparation of filling liquid 101)
8 parts by mass of polyvinyl alcohol (PVA-403, saponification degree 79 mol%, polymerization degree 300, manufactured by Kuraray Co., Ltd.) was added to 92% by mass of pure water and stirred. Next, the temperature was raised to 90 ° C., allowed to stand for 3 hours, and then cooled to 40 ° C. to prepare a filling liquid 101 containing polyvinyl alcohol having a low saponification degree and a low polymerization degree.
Filling liquid 101 is fed to the piping from the coating liquid preparation kettle to the coating liquid storage kettle, the piping including the circulation path R1 in the circulation process, and the supply path L1 from the coating liquid storage kettle to the coating device to fill the piping. .
(Preparation of filling liquids 102 to 107)
In the preparation of the filling liquid 101, except that the polyvinyl alcohol was changed to the following Table 1, filling liquids 102 to 107 were prepared in the same manner, and filled in the piping in the same manner as described above.
The polyvinyl alcohol (L-8 and PVA-424H) used in the filling liquids 105 and 107 are products of Kuraray Co., Ltd., and the polyvinyl alcohol (JP-05) used in the filling liquid 106 is Japanese vinegar. A product from Bi Poval Co., Ltd. was used.

(Preparation of filling liquid 108)
As the filling liquid 108, pure water was used.

<Preparation of coating solution>
(Preparation of coating solution for low refractive index layer)
In a coating solution preparation kettle equipped with a stirrer, 38 parts by mass of colloidal silica (Snowtex (registered trademark) OXS, solid content 10% by mass, manufactured by Nissan Chemical Industries, Ltd.) is heated to 45 ° C., and 3% by mass boric acid aqueous solution 3 parts by mass was added and stirred. Furthermore, polyvinyl alcohol (JP-45, degree of polymerization 4500, degree of saponification 87 mol%, manufactured by Nihon Acetate / Poval Co., Ltd.) 39 mass parts of water-soluble polymer and 39 mass parts of surfactant and 5 mass% of surfactant 1 part by mass of an aqueous solution (SOFTAZOLINE LSB-R, manufactured by Kawaken Fine Chemical Co., Ltd.) was added and stirred in this order at 45 ° C. to prepare a low refractive index layer coating solution.

(Preparation of high refractive index layer coating solution)
((Preparation of silica-attached titanium dioxide 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, average particle size 5 nm, rutile titanium dioxide particles, manufactured by Sakai Chemical Industry Co., Ltd.), heating to 90 ° C. did. Next, 0.5 part 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 0.5 mass%) was gradually added. . Next, a heat treatment at 175 ° C. for 18 hours in an autoclave was performed, and after cooling, the resultant was concentrated with an ultrafiltration membrane, whereby a titanium dioxide sol (hereinafter referred to as SiO ₂₎ having a solid content concentration of 6% by mass adhered to the surface. Simply referred to as “silica-attached titanium dioxide sol”).

((Preparation of coating solution for high refractive index layer))
48 parts by mass of a 1.92% by mass aqueous citric acid solution is added to 140 parts by mass of the silica-attached titanium dioxide sol (solid content: 20.0% by mass) obtained above in a coating liquid preparation kettle equipped with a stirrer. 113 mass parts of 8 mass% polyvinyl alcohol aqueous solution (PVA-135, polymerization degree 3500, saponification degree 98 mol%, Kuraray Co., Ltd. product) was added and stirred. Thereafter, 0.4 parts by mass of a 5% by weight aqueous solution of a surfactant (SOFTAZOLINE LSB-R, manufactured by Kawaken Fine Chemical Co., Ltd.) was added and stirred to prepare a high refractive index layer coating solution.

<Production of infrared shielding film>
(Preparation of infrared shielding film 201)
The low refractive index layer coating liquid stored in the coating liquid preparation kettle is discharged to the filtration device at a flow rate of 20 L / min using a rotary pump that is a liquid feeding device at the same time as the filling liquid 101 is discharged. The coating solution for the low refractive index layer was filtered and sent to the coating solution storage tank. Filtration was performed by feeding the low refractive index layer coating liquid to the filter at a flow rate of 20 L / min using a filter 250L-SLP-200 (manufactured by Loki Techno Co., Ltd.) and a rotary pump.
The coating liquid for the low refractive index layer stored in the coating liquid storage tank is discharged to the dispersion device Milder MDN306V at a flow rate of 20 L / min using the liquid feeding device rotary pump at the same time as the filling liquid 101 is discharged. Shearing was performed. Such a dispersing device is a shearing device equipped with a standard type rotor and stator. Using this milder, the rotor was rotated at a rotational speed of 5000 rpm, and the coating solution was sheared.
Subsequently, the filling liquid 101 was discharged, and at the same time, the coating liquid for the low refractive index layer was filtered by a filtration device. Filtration was performed by passing a coating solution for a low refractive index layer through the filter at a flow rate of 20 L / min using a filter 250L-SLP-200 (manufactured by Loki Techno Co., Ltd.) and a rotary pump.
The coating solution for the low refractive index layer that had been subjected to the filtration treatment was returned again to the coating solution storage tank through the circulation path.
Here, when the coating liquid for the low refractive index layer is returned to the coating liquid storage tank, the filling liquid 101 filled in the pipe is discharged at the same time as described above, and at the same time, the coating liquid is fed to the coating liquid storage tank. Returned. The circulation process was performed for 30 minutes to obtain a coating solution 1 for a low refractive index layer subjected to the circulation process. In another series, the same treatment was performed on the above-described coating solution for high refractive index to obtain coating solution 1 for high refractive index layer.
Finally, the filling liquid 101 filled in the pipe is discharged from the filtration device through the supply path, and at the same time, the low refractive index coating solution and the high refractive index coating solution subjected to the circulation process are fed to the coating device. To a simultaneous multi-layer slide coater, and using this slide coater, a polyethylene terephthalate (PET) film having a width of 300 mm and a thickness of 50 μm (manufactured by Toyobo Co., Ltd., Cosmo Shine (registered trademark) A4300, double-sided adhesive layer) On top, the lowermost layer is the low refractive index layer, the low refractive index layer / the high refractive index layer are alternately applied at the same time at 10 layers at a speed of 50 m / min, and dried at 50 ° C. using a drying apparatus, An infrared shielding film 201 was produced.

(Preparation of infrared shielding film 202)
In the production of the infrared shielding film 201, an infrared shielding film 202 was produced in the same manner except that the coating liquid was fed after the filling liquid was completely discharged.

(Preparation of infrared shielding films 203-209)
In the production of the infrared shielding film 201, except that the filling liquid was changed as shown in Table 2 below, the filling liquids 102 to 108 were filled in the same manner as described above to produce infrared shielding films 203 to 209. did.
(Preparation of infrared shielding film 210)
In the production of the infrared shielding film 201, the simultaneous multi-layer slide coater is changed to a single-layer slide coater, and the filling liquid 101 filled in the pipe is discharged and at the same time a circulation process is performed. The infrared shielding film 210 of this invention was produced by the same method except having sent only liquid.
<Evaluation of infrared shielding film>
(Verification of coating failure by visual inspection)
About each infrared shielding film of the initial stage (position 400m from the start of application) manufactured above, visually confirm the range of length 10m x width 0.25m, visually confirm the number of tails and streaks, By dividing the value by 2.5, the average number of coating failures per 1 m × 1 m was calculated.
: 0 / m ²
○: More than 0 to 0.1 / m ²
Δ: More than 0.1 to 1.0 piece / m ²
×: More than 1.0 to 10 pieces / m ²
XX: Over 10 / m ²

(Measurement of haze value)
The haze value was cut on an initial infrared shielding film (at a position 500 m from the start of application), measured by Nippon Denshoku Industries Co., Ltd. (NDH2000), and evaluated as follows.
A: 1.2% or less B: Over 1.2% to 1.5% or less Δ: Over 1.5% to 2% or less X: Over 2% The results obtained are shown in Table 2 below.

  From the above results, it can be seen that the infrared shielding films 201 to 208 of the present invention have no coating failure and low haze.

DESCRIPTION OF SYMBOLS 100 Optical film manufacturing system 101 Coating liquid preparation pot 102,105,109 Liquid feeding apparatus 103,108 Filtration apparatus 104 Coating liquid storage pot 106 Dispersion apparatus 107 Defoaming apparatus 110 Coating apparatus 111 Set apparatus 112 Drying apparatus R1 Circulation path L1 Supply path

Claims (7)

An optical film manufacturing method comprising a step of forming an optical interference layer composed of one layer or a plurality of layers using a coating liquid containing inorganic oxide fine particles and polyvinyl alcohol on at least one surface of a support. ,
In the pipe for liquid feeding in the step, a filling liquid containing polyvinyl alcohol having a lower saponification degree and a lower polymerization degree than the polyvinyl alcohol contained in the coating liquid is filled in advance, and then the coating liquid When the liquid is introduced into the pipe, the filling liquid is discharged from the pipe to the outside, and the coating liquid is fed into the pipe and applied onto the support to form the optical interference layer. The manufacturing method of the optical film characterized by the above-mentioned. The optical interference layer is composed of a plurality of layers adjacent to each other and having different refractive indexes,
The respective layers constituting the optical interference layer contain the inorganic oxide fine particles and the polyvinyl alcohol, respectively, and the polyvinyl alcohols contained in layers adjacent to each other have different saponification degrees. Item 2. A method for producing an optical film according to Item 1.   The method for producing an optical film according to claim 2, wherein the coating liquid for forming each layer constituting the optical interference layer is sent simultaneously with discharging the filling liquid to the outside of the pipe.   The degree of saponification of the polyvinyl alcohol contained in the filling liquid is in the range of 73 to 85 mol%. The optical film according to any one of claims 1 to 3, Production method.   The method for producing an optical film according to any one of claims 1 to 4, wherein the degree of polymerization of the polyvinyl alcohol contained in the filling liquid is in a range of 300 to 2,000.   The said optical film is an optical reflection film, The manufacturing method of the optical film as described in any one of Claim 1- Claim 5 characterized by the above-mentioned.   The method for producing an optical film according to claim 6, wherein the optical reflection film is an infrared shielding film.

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