JP2012046554A - Anti-fogging film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anti-fogging film excellent in anti-fogging property and also in adhesiveness of a transparent support layer to an anti-fogging layer.SOLUTION: The anti-fogging film has a layer structure such that the anti-fogging layer containing the crosslinked material of polyvinyl alcohol-based resin is directly laminated to the transparent support layer. The film is produced by performing a plasma treatment on at least one side of the transparent support film, then coating on the treated surface, a coating liquid containing an acetoacetyl group-containing polyvinyl alcohol-based resin and glyoxylate, and drying.

Description

  The present invention relates to an antifogging film, and more particularly to an antifogging film having a transparent support layer and an antifogging layer containing a crosslinked product of a polyvinyl alcohol resin.

  Cloudiness due to condensation on the glass surface hinders visibility. As countermeasures, methods such as keeping the glass warm with a heating wire or superhydrophilic treatment on the surface of the glass are taken, but in any case, an increase in cost is inevitable. Therefore, as a simple means, a method of attaching an antifogging film to the glass surface has been proposed and put into practical use.

For the antifogging layer of such an antifogging film, a polymer material having excellent hydrophilicity and transparency is used, and a typical example is a polyvinyl alcohol resin (hereinafter abbreviated as PVA resin). However, since the PVA-based resin is a water-soluble polymer, it inherently has poor water resistance, and has a problem that the physical properties change greatly when moisture is absorbed or wet.
For such a problem, a method of crosslinking a PVA resin is effective. For example, an antifogging layer having a denatured PVA resin having a reactive acetoacetyl group in the side chain and an antifogging layer containing a crosslinking agent. Sheets have been proposed. (For example, refer to Patent Document 1.)
Further, as a crosslinking agent for an acetoacetyl group-containing PVA-based resin (hereinafter abbreviated as AA-PVA-based resin), an anti-fogging using a glyoxylate capable of obtaining a crosslinked product having excellent water resistance and color resistance with time. Agents have also been proposed. (For example, see Patent Document 2.)

JP 2000-00935 A JP 2010-77385 A

The antifogging film usually has a transparent support layer in order to enhance strength retention and handleability, and the antifogging layer is formed on the transparent support layer. However, since the anti-fogging film is usually used under high humidity, it is necessary to consider changes in physical properties when both layers absorb moisture.
For example, hydrophilic polymer such as PVA resin used for anti-fogging layer and hydrophobic thermoplastic resin used for transparent support layer are generally poor in affinity, so both layers during moisture absorption In order to prevent delamination or the like due to the difference in the dimensional change rate, it is necessary to interpose an adhesive layer between the two layers. For example, in Patent Document 1, an undercoat layer mainly composed of a polymer binder such as gelatin or latex is provided.

However, in order to provide an undercoat layer between the transparent support layer and the antifogging layer, for example, a step of applying and drying the undercoat layer coating solution on the surface of the transparent support film is required, which is disadvantageous in terms of production cost. It is.
It is also disadvantageous in that the thickness of the entire film may be increased by the undercoat layer, and characteristics such as flexibility may be affected by the undercoat layer.

  That is, the present invention aims to provide an anti-fogging film having excellent anti-fogging performance, having an anti-fogging layer and a transparent support layer directly laminated, and having good adhesion between both layers during moisture absorption. It is.

  The present invention is an antifogging film having a layer structure in which a transparent support layer and an antifogging layer containing a cross-linked product of a PVA resin are directly laminated as a result of intensive studies in view of the above circumstances. The object of the present invention is achieved by an anti-fogging film obtained by plasma-treating at least one surface of a film and then applying and drying a coating liquid containing an AA-PVA-based resin and glyoxylate on the treated surface. As a result, the present invention has been completed.

  That is, the present invention uses a cross-linked product of AA-PVA-based resin as a cross-linked product of PVA-based resin used in the antifogging layer, selects glyoxylate as a cross-linking agent of such AA-PVA-based resin, and further supports transparent support. The greatest feature is that plasma treatment is selected as the body surface treatment method, and these are combined.

The anti-fogging film of the present invention has an excellent anti-fogging performance, and an anti-fogging layer and a transparent support layer are directly laminated, has good adhesion between both layers, particularly when moisture is absorbed, and delamination occurs. It is hard to happen.
In addition, since it is not necessary to provide an undercoat layer between the antifogging layer and the support layer, the production cost can be reduced.

The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and is not limited to these contents.
Hereinafter, the present invention will be described in detail.

(Transparent support layer)
As a material of the transparent support layer in the antifogging film of the present invention, a known transparent resin can be used, for example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polyolefins such as polyethylene and polypropylene. And polyamide, polycarbonate, polystyrene, polyvinyl chloride, acrylic resin and the like.
Among them, polyesters excellent in strength, durability, dimensional stability and transparency are preferable, and polyethylene terephthalate is particularly preferable.

Such polyethylene terephthalate (hereinafter abbreviated as PET) is mainly composed of ethylene glycol and terephthalic acid, but other dicarboxylic acid components and glycol components as long as the object of the present invention is not impaired. May be copolymerized.
Examples of the dicarboxylic acid component include isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, and cyclohexane-1,4-dicarboxylic acid. Examples of the glycol component include propylene glycol, butanediol, neopentyl glycol, diethylene glycol and the like.

In the present invention, the transparent support film used for the transparent support layer can be any of an unstretched film, a uniaxially stretched film, and a biaxially stretched film, but biaxially stretched from the viewpoint of transparency and strength. A film is preferred.
Moreover, the thickness of this transparent support body film, ie, the thickness of the transparent support body in the anti-fogging film of this invention, is 1-500 micrometers normally, Especially it is 3-250 micrometers, Furthermore, it is 5-200 micrometers. The preferred thickness varies depending on the purpose and usage of the antifogging film, but generally, if it is too thin, the strength of the antifogging film tends to be insufficient, and if it is too thick, the flexibility tends to be impaired. is there.

  In addition, the transparent support film, particularly PET film, usually contains various additives such as inorganic fine particles, waxes, antioxidants, antistatic agents, crystal nucleating agents, viscosity reducing agents, thermal stability. An agent, an anti-coloring agent, an ultraviolet absorber and the like may be contained.

[Plasma treatment]
Next, plasma treatment applied to at least one surface of the transparent support film, that is, the surface laminated with the antifogging layer will be described.
In such plasma treatment, a high-frequency voltage is applied between the opposing electrodes to discharge, the atmosphere gas is brought into a plasma state, and the surface of the object to be treated is exposed to the plasma state gas to activate the surface. .
As such an atmospheric gas, nitrogen, oxygen, argon, helium, or the like can be used. Among them, nitrogen is preferably used in terms of safety, exhaust gas aftertreatment, running cost, and the like.

Processing the intensity of the plasma treatment is usually 0.1~100W / cm ^2, particularly 0.2~80W / cm ^2, in particular the range of 0.5 to 50 / cm ² is preferably used. If the treatment strength is too weak, the surface treatment effect of the support film is small, and there is a tendency that sufficient adhesive force with the antifogging layer cannot be obtained. Moreover, when the processing strength is too strong, the surface of the support film may be deteriorated.

  The flow rate of the atmospheric gas during the plasma processing is usually 1 to 5000 L / min per 1 m of the effective width of the plasma processing surface, and particularly in the range of 2 to 2500 L / min. If the flow rate is too low, the amount of plasma generated may be small and a sufficient treatment effect may not be obtained. If the flow rate is too high, the amount of gas used increases, which is disadvantageous in terms of cost.

The present invention is characterized in that a plasma treatment is applied to the laminated surface of the transparent support with the antifogging layer, and in addition to this, a surface that is irradiated with energy rays such as ultraviolet rays, electron beams, and ion rays. It is also possible to use treatment in combination. In particular, as an ultraviolet ray source, a D ₂ lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, an Xe lamp, an Hg-Xe lamp, a halogen lamp, an arc discharge, a corona discharge, a silent discharge discharge lamp, an excimer laser, an Ar + laser, or a Kr + A laser oscillation device such as a laser or an N2 laser is preferably used.
The surface treatment with such energy rays can be performed before, after or simultaneously with the plasma treatment.

[AA-modified PVA resin]
Next, the glyoxylic acid cross-linked product of the AA-PVA-based resin contained in the antifogging layer in the antifogging film of the present invention will be described.
First, the AA-PVA-based resin will be described.
The AA-PVA-based resin used in the antifogging layer of the present invention is a PVA-based resin having an acetoacetyl group in the side chain, and the content thereof is usually about 0.1 to 20 mol% of the entire structural unit. The other parts are a vinyl alcohol structural unit and a vinyl acetate structural unit in the same manner as a normal PVA resin.

  The method for producing the AA-PVA-based resin is not particularly limited. For example, a method of reacting a PVA-based resin with diketene, a method of reacting a PVA-based resin with acetoacetate, and transesterification, acetic acid A method of saponifying a copolymer of vinyl and vinyl acetoacetate can be mentioned, but since the production process is simple and a high-quality AA-PVA-based resin is obtained, the PVA-based resin and diketene are reacted. It is preferable to manufacture by a method. Hereinafter, this method will be described.

  As the PVA resin used as a raw material, a saponified product of a vinyl ester monomer polymer or a derivative thereof is generally used. Examples of the vinyl ester monomer include vinyl formate, vinyl acetate, vinyl propionate, and valeric acid. Examples include vinyl, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl versatate, and vinyl acetate is preferably used from the viewpoint of economy.

Further, a saponified product of a copolymer of a vinyl ester monomer and a monomer copolymerizable with the vinyl ester monomer can be used. Examples of the copolymer monomer include ethylene, propylene, isobutylene, α- Olefins such as octene, α-dodecene, α-octadecene, hydroxy such as 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 3,4-dihydroxy-1-butene Derivatives such as group-containing α-olefins and acylates thereof, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, undecylenic acid, salts, monoesters, or dialkyl esters thereof , Nitriles such as acrylonitrile and methacrylonitrile, diacetone acrylate Amides such as amide, acrylamide and methacrylamide, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid or salts thereof, alkyl vinyl ethers, dimethylallyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinyl Vinyl compounds such as ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxolane, glycerol monoallyl ether, substituted vinyl acetates such as isopropenyl acetate and 1-methoxyvinyl acetate, vinylidene chloride, 1, 4-diacetoxy-2-butene, 1,4-dihydroxy-2-butene, vinylene carbonate and the like can be mentioned.
The introduction amount of the copolymerization monomer varies depending on the type of the monomer, and cannot be generally specified. However, it is usually 10 mol% or less, particularly 5 mol% or less of the total structural unit, and if it is too much, the water solubility is impaired. Or compatibility with the cross-linking agent may be reduced.

  In addition, the polymerization temperature at the time of polymerizing and copolymerizing vinyl ester monomers and other monomers is adjusted, and the amount of heterogeneous bonds generated relative to the 1,3-bond generated is increased or decreased to increase the amount of 1, It is possible to use one having a 2-diol bond of about 1.0 to 3.5 mol%.

  The introduction of acetoacetyl groups by the reaction of PVA resin obtained by saponifying the polymer and copolymer of the above vinyl ester monomer and diketene involves direct reaction of PVA resin with gaseous or liquid diketene. Alternatively, after adsorbing and occluding an organic acid in a PVA resin in advance, a gaseous or liquid diketene is sprayed and reacted in an inert gas atmosphere, or a mixture of an organic acid and a liquid diketene is applied to the PVA resin. Methods such as spraying and reacting are used.

  As a reaction apparatus for carrying out the above reaction, an apparatus that can be heated and has a stirrer is sufficient. For example, a kneader, a Henschel mixer, a ribbon blender, other various blenders, and a stirring and drying apparatus can be used.

  The average polymerization degree of the AA-PVA-based resin thus obtained may be appropriately selected depending on the application, but is usually 300 to 5000, particularly 500 to 2000, and more preferably 1000 to 1500. If the average degree of polymerization is too small, the strength of the antifogging layer tends to be insufficient or sufficient water resistance cannot be obtained. Conversely, if it is too large, the viscosity of the coating solution for forming the antifogging layer Tends to be too high, and workability tends to decrease.

  The saponification degree of the AA-PVA-based resin used in the present invention is usually 60 mol% or more, more preferably 80 mol% or more, particularly 90 mol% or more, particularly 98 mol% or more. Preferably used. If the degree of saponification is too low, the antifogging property tends to be insufficient because the affinity between the obtained antifogging layer and water decreases. The average degree of polymerization and the degree of saponification are measured according to JIS K6726.

  Further, the content of acetoacetyl groups in the AA-PVA-based resin (hereinafter abbreviated as AA degree) is usually 0.1 to 20 mol%, further 1 to 15 mol%, particularly 3 to 3. What is 10 mol% is generally used. If the content is too small, the water resistance of the antifogging layer tends to be insufficient. Conversely, if the content is too large, the affinity for the antifogging layer and water decreases, and the antifogging precision tends to be insufficient. There is.

In the present invention, it is preferable that all of the PVA-based resins are AA-based PVA-based resins, but PVA-based resins other than the AA-based PVA-based resins may be used in combination, and the content thereof is usually 20% by weight or less. In particular, it is preferably 10% by weight or less.
Examples of various PVA-based resins other than the AA-PVA-based resin include unmodified PVA and various modified PVA-based resins, such as a vinyl ester monomer and a monomer copolymerizable with the vinyl ester monomer. Copolymer saponified products can be used. Examples of such monomers include ethylene, propylene, isobutylene, α-octene, α-dodecene, olefins such as α-octadecene, 3-buten-1-ol, 4 -Derivatives such as hydroxy group-containing α-olefins such as penten-1-ol, 5-hexen-1-ol, 3,4-dihydroxy-1-butene and acylated products thereof, acrylic acid, methacrylic acid, crotonic acid, Unsaturated acids such as maleic acid, maleic anhydride, itaconic acid, undecylenic acid, their salts, monoesters, Or nitriles such as dialkyl esters, acrylonitrile and methacrylonitrile, amides such as diacetone acrylamide, acrylamide and methacrylamide, olefin sulfonic acids such as ethylene sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid or salts thereof, alkyl vinyl ether , Dimethylallyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxolane, vinyl compounds such as glycerol monoallyl ether, isopropenyl acetate, 1- Examples thereof include substituted vinyl acetates such as methoxyvinyl acetate, vinylidene chloride, 1,4-diacetoxy-2-butene, 1,4-dihydroxy-2-butene, vinylene carbonate and the like.

  The AA-PVA-based resin of the present invention includes alkali metal acetates such as sodium acetate used or produced as a by-product in the production process (mainly the alkali metal hydroxide used as the saponification catalyst and the polyvinyl acetate kenne). Derived from a reaction product with acetic acid produced by the chemical conversion), an organic acid such as acetic acid (derived from an organic acid occluded in PVA during reaction with diketene when introducing an acetoacetate group into a PVA resin) , Methanol, methyl acetate and other organic solvents (derived from the reaction solvent for PVA resin, the cleaning solvent for the production of AA-PVA, etc.) may partially remain.

[Glyoxylate]
Next, the glyoxylate used as the crosslinking agent for the AA-PVA-based resin in the antifogging layer of the antifogging film of the present invention will be described.
Examples of the glyoxylate include metal salts and amine salts of glyoxylic acid. Examples of the metal salt include alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium and calcium, titanium, zirconium, Transition metals such as chromium, manganese, iron, cobalt, nickel, copper, other metals such as zinc and aluminum and metal salts of glyoxylic acid, and amine salts include amines such as ammonia, monomethylamine, dimethylamine, and trimethylamine And salts of glyoxylic acid.
Among these, metal salts are preferable from the viewpoint of obtaining an antifogging layer having excellent water resistance, and alkali metal salts are particularly preferably used from the viewpoint of excellent antifogging properties.

  As a method for producing glyoxylate, a known method can be used. For example, (1) a method based on a neutralization reaction of glyoxylic acid, (2) a salt of glyoxylic acid with an acid dissociation constant larger than glyoxylic acid, And (3) a method by alkaline hydrolysis of glyoxylic acid ester (see, for example, JP-A-2003-300996). In particular, when the alkaline compound used for the neutralization reaction with glyoxylic acid is highly water-soluble, the method of (1) is a salt of an acid whose glyoxylate salt is low in water solubility and has an acid dissociation constant greater than glyoxylic acid. When the water solubility of is high, the method (2) is preferably used.

The method (1) is usually carried out using water as a medium, glyoxylic acid and an alkaline compound, for example, various metal hydroxides or amine compounds are reacted in water, and the precipitated glyoxylate is filtered off. It can be produced by drying.
The method (2) is also generally carried out in water, and glyoxylate can be obtained in the same manner as the method (1). Examples of the acid salt having a larger dissociation constant than glyoxylic acid used in the method (2) include, for example, alkali metal or alkaline earth metal salts of aliphatic carboxylic acids such as sodium acetate, calcium acetate, and calcium propionate. Can be mentioned.

  The cross-linking agent of the present invention may contain raw materials used in the production of glyoxylate, impurities contained in the raw materials, by-products during production, etc., for example, glyoxylic acid, metal hydroxide , Amine compounds, aliphatic carboxylates, glyoxal, oxalic acid, and oxalate, glycolic acid or glycolate may be contained.

  In addition, the glyoxylate in the present invention is acetalized with an alcohol having 3 or less carbon atoms such as methanol and ethanol, a diol having 3 or less carbon atoms such as ethylene glycol and propylene glycol, and hemiacetal. Including the compound. Such an acetal group and a hemiacetal group have reactivity with various base materials in the same manner as the aldehyde group because the alcohol is easily eliminated in water or at a high temperature and takes an equilibrium state with the aldehyde group.

  The amount of glyoxylate is usually 0.1 to 30% by weight, more preferably 1 to 20% by weight, particularly 2 to 15% by weight, particularly 4 to 10% by weight, based on the AA-PVA resin. A range is preferably used. If the blending amount is too small, the water resistance of the antifogging layer tends to be insufficient. Conversely, if the blending amount is too large, the stability of the coating solution for forming the antifogging layer tends to decrease.

  In addition, although this invention is characterized by using a glyoxylate as a crosslinking agent of the AA-PVA type resin used for an anti-fogging layer, AA-PVA type | system | group is within the range which does not inhibit the effect of this invention. You may use together a well-known thing as a crosslinking agent of resin. Such cross-linking agents include water-soluble titanium compounds and polyvalent metal compounds such as water-soluble zirconium, amine compounds such as ethylenediamine and metaxylylenediamine, hydrazine compounds such as adipic acid dihydrazide, and methylol groups such as methylolated melamine. Examples thereof include compounds and aldehyde group-containing compounds such as glyoxal.

[Anti-fog film]
The antifogging film of the present invention has a layer structure in which a transparent support layer and an antifogging layer containing a cross-linked product of glyoxylate of AA-PVA-based resin are directly laminated.
Such an antifogging layer is formed by applying and drying a coating liquid containing an AA-PVA-based resin and glyoxylate on the surface of the transparent support film that has been subjected to plasma treatment.

As such a coating solution, an aqueous coating solution containing water as a main medium is preferable because it is a good solvent for the AA-PVA-based resin and has a small environmental load. For the purpose of adjusting the drying speed and adjusting the wettability with the support film, an organic solvent having miscibility with water, for example, alcohols having 1 to 3 carbon atoms such as methanol and ethanol, acetone and methyl ethyl ketone. It is also possible to mix a small amount of ketones such as.
In addition, such aqueous coating liquids include additives such as inorganic fine particles, ultraviolet absorbers, antioxidants, antifoaming agents, antifungal agents, antiseptics, leveling agents, etc. within the range not impairing the characteristics of the present invention. May be blended.

  The concentration of the aqueous coating solution is usually 1 to 30% by weight, particularly 3 to 20% by weight, particularly 5 to 15% by weight. If the concentration is too small, the thickness of the coating layer obtained by one application and drying becomes small, so that a plurality of coatings may be required to obtain a desired thickness. On the other hand, if the concentration is too large, the viscosity of the coating solution increases, and the workability during coating may decrease, or it may be difficult to obtain a coating layer having a uniform thickness.

The pH of such an aqueous coating solution is usually 2 to 10, preferably 3 to 10, more preferably 4 to 9, and the adjustment thereof can be carried out with inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, citric acid, tartaric acid. It can carry out by addition of organic acids, such as. If the pH is too low, it may cause corrosion of the equipment used for the production of the coating liquid or the coating on the support. Therefore, countermeasures are necessary. The properties tend to decrease, the viscosity tends to increase, and the pot life tends to be shortened.

  The method for preparing such an aqueous coating solution is not particularly limited. For example, (i) a method in which a mixture of AA-PVA-based resin and glyoxylate is poured into water and dissolved, (ii) AA-PVA in advance And (iii) a method in which glyoxylate is added to an aqueous solution of an AA-PVA-based resin and mixed.

In applying the aqueous coating solution thus obtained on the surface of the transparent support that has been subjected to plasma treatment, a known coating method such as a roll coater method, an air doctor method, a blade coater method, or the like is used. be able to.
Such coating amount is different depending on the concentration of the coating liquid, can not be said sweepingly, usually from 1 to 10,000 g / ^{m 2,} in particular 10~5000g / ^{m 2,} in particular of 100 to 2000 g / ^{m 2} A range is preferably used.

The protective layer coated on the support needs to be dried next, but the drying method is not particularly limited, and a known method can be used, and the heat source can be hot air, infrared rays, radiant heat. Or a combination of them can be used. The drying temperature is usually from 70 to 150 ° C., particularly from 80 to 130 ° C., particularly from 90 to 120 ° C. Further, the drying time varies depending on the drying temperature and cannot be generally specified, but is usually 1 to 20 minutes, particularly 3 to 10 minutes.
Industrially, it is desirable that the coating step and the drying step of the above-described coating liquid be performed continuously.

  The thickness of the antifogging layer in the antifogging film of the present invention is usually from 1 to 1000 μm, more preferably from 2 to 400 μm, especially from 3 to 100 μm, especially from 5 to 20 μm. The strength of the antifogging layer may be insufficient, and if it is too thick, warping may occur due to a difference in dimensional change in the thickness direction due to moisture absorption or the like.

The anti-fogging film having a layer structure in which the transparent support layer and the anti-fogging layer containing the cross-linked product of the AA-PVA-based resin by glyoxylate are directly laminated is provided to further provide functions. It is also possible to laminate these layers.
For example, sticking to a glass surface can be facilitated by providing an adhesive layer on the surface opposite to the surface of the transparent support layer on which the antifogging layer is laminated.
Moreover, durability can be improved by providing the moisture-permeable protective layer on the anti-fogging layer.

  The antifogging film of the present invention thus obtained has a total thickness of usually 2 to 2000 μm, particularly 5 to 1000 μm, particularly 10 to 100 μm. If the thickness is too thin, the strength may be insufficient or the handleability may be difficult when sticking to glass or the like. Conversely, if it is too thick, the flexibility tends to be insufficient and the handleability tends to decrease. There is.

Hereinafter, the present invention will be described with reference to examples. However, the present invention is not limited to the description of the examples unless it exceeds the gist.
In the examples, “parts” and “%” mean weight basis unless otherwise specified.

Production Example 1: AA-PVA-based resin (1)
In a ribbon blender with temperature controller, unmodified PVA resin (average polymerization degree 1200, saponification degree 99.2 mol%) is charged into a kneader, 3600 parts, and 1000 parts of acetic acid is added to swell, and stirred at a rotation speed of 20 rpm. Then, after the temperature was raised to 60 ° C., 550 parts of diketene was added dropwise over 3 hours, and the reaction was further continued for 1 hour. After completion of the reaction, the mixture was washed with methanol and dried at 70 ° C. for 6 hours to obtain AA-PVA resin (1). The obtained AA-modified PVA resin (1) had an AA degree of 5.3 mol%, a saponification degree of 98.9 mol%, and an average degree of polymerization of 1200.

Production Example 2: Sodium Glyoxylate To 456 g (3.10 mol) of 50% aqueous glyoxylic acid solution in a 2 L two-necked reaction vessel, 645 g (3.22 mol) of 20% aqueous sodium hydroxide solution was added, and the resulting white crystals were After filtration and washing with water, the mixture was dried at 50 ° C. for 1 hour to obtain 210 g (1.84 mol, yield 59.5%) of sodium glyoxylate.

Production Example 3: Calcium Glyoxylate 268 g (0.34 mol) of a 20% aqueous solution of calcium acetate was added dropwise to 202 g (0.68 mol) of a 25% aqueous solution of glyoxylic acid in a 2 L 2-neck reactor over 2 hours. The white crystals were filtered, washed with water, and dried at 50 ° C. for 1 hour to obtain 70.3 g (0.32 mol, yield 93.6%) of calcium glyoxylate.

Example 1
One surface of a PET film (“Lumirror T60” manufactured by Toray Industries, Inc., 100 μm thick) was subjected to plasma treatment under the conditions shown below.
Equipment: “Atmospheric pressure plasma surface treatment equipment” manufactured by Sekisui Chemical Co., Ltd.
Processing intensity: 28 W / cm ²
Conveyance speed: 1000mm / s
Nitrogen flow rate: 25 mL / min

Next, 0.5 parts by weight of sodium glyoxylate obtained in Production Example 2 as a cross-linking agent (100 parts by weight of AA-PVA) was added to 100 parts by weight of the 10% aqueous solution of AA-PVA-based resin (1) obtained in Production Example 1. 5 parts by weight with respect to 100 parts by weight of the resin) and mixed and stirred to obtain an aqueous coating solution for forming an antifogging layer.
The coating solution is coated on the surface of the PET film subjected to plasma treatment with a 100 μm applicator, dried in a hot air dryer at 105 ° C. for 5 minutes, and has an antifogging layer having a thickness of 10 μm. A film was obtained.
The obtained anti-fogging film was evaluated in the following manner.

<Anti-fogging property>
No. made by Saya Glass Industrial Co., Ltd. 10 mL of 95 ° C. warm water was placed in a 3K mayonnaise bottle, and an anti-fogging film was placed on the mouth of the bottle so that the anti-fogging layer was on the inside, and the time until fogging with steam was measured. The results are shown in Table 1.

<Interlayer adhesion>
Three drops of water were dropped on the antifogging layer of the antifogging film with a dropper, and the state after 30 minutes was visually observed and evaluated as follows. The results are shown in Table 1.
○: No peeling is observed between the transparent support layer and the antifogging layer.
X: Peeled between the transparent support layer and the antifogging layer.

Example 2
In Example 1, an antifogging film was produced in the same manner as in Example 1 except that the amount of sodium glyoxylate added was 0.3 parts by weight (3 parts by weight with respect to 100 parts by weight of AA-PVA-based resin). Evaluation was performed in the same manner. The results are shown in Table 1.

Example 3
In Example 1, an antifogging film was prepared in the same manner as in Example 1 except that the amount of sodium glyoxylate added was 1 part by weight (10 parts by weight with respect to 100 parts by weight of the AA-PVA resin). evaluated. The results are shown in Table 1.

Example 4
In Example 1, an antifogging film was prepared in the same manner as in Example 1 except that calcium glyoxylate obtained in Production Example 3 was used instead of glyoxyl sodium, and interlayer adhesion was similarly evaluated. The results are shown in Table 1.

Comparative Examples 1 and 2
An antifogging film was prepared in the same manner as in Examples 1 and 4 except that the transparent support was not subjected to plasma treatment in Examples 1 and 4, and interlayer adhesion was similarly evaluated. The results are shown in Table 1.

  From the above results, the antifogging film having an antifogging layer containing a cross-linked product of the AA-PVA-based resin by glyoxylate showed excellent antifogging properties. In addition, when the transparent support film was subjected to plasma treatment, the transparent support layer and the antifogging layer did not delaminate even when water droplets adhered, and had excellent adhesiveness.

  The anti-fogging film of the present invention is excellent in anti-fogging, and even though the support layer and the anti-fogging layer are directly related to each other, the both layers have good adhesion, and delamination due to moisture absorption etc. Since it does not occur, it is possible to add anti-fogging properties by sticking to glass etc., and it can be applied to window glass in buildings, mirrors in bathrooms and bathrooms, food showcases, various displays, etc. Conceivable.

Claims (4)

An antifogging film having a layer structure in which a transparent support layer and an antifogging layer containing a crosslinked product of a polyvinyl alcohol-based resin are directly laminated, and after plasma-treating at least one surface of the transparent support film, An anti-fogging film obtained by applying and drying a coating liquid containing an acetoacetyl group-containing polyvinyl alcohol resin and glyoxylate on the treated surface. The anti-fogging film according to claim 1, wherein the transparent support is mainly composed of a polyester resin. The antifogging film according to claim 1 or 2, wherein the glyoxylate is an alkali metal salt of glyoxylic acid. The antifogging film according to any one of claims 1 to 3, wherein the antifogging layer has a thickness of 1 to 1000 µm.