阅读说明：本技术 防雾膜 (Antifogging film ) 是由 片野祥吾 藤原祐介 于 2019-02-19 设计创作，主要内容包括：本发明提供一种兼具初始防雾性、长期防雾性及过渡期间内的防雾性且这些防雾性的耐久性优异的防雾膜。防雾膜(10)具备膜基材(11)、第1层即中间层(12)及第2层即树脂层(13)。膜基材(11)由酰基取代度为2.00以上且2.97以下的范围内的纤维素酰化物形成。中间层(12)由酰基取代度小于膜基材(11)的纤维素酰化物或纤维素形成。树脂层(13)具有羟基、酰胺结构及吡咯烷酮结构中的任一种且含有分子量为30000以上的聚合物。(The invention provides an antifogging film which has initial antifogging property, long-term antifogging property and antifogging property in a transition period and has excellent durability of the antifogging properties. The antifogging film (10) is provided with a film base (11), a 1 st intermediate layer (12), and a 2 nd resin layer (13). The film base (11) is formed from a cellulose acylate having an acyl substitution degree within a range of 2.00 or more and 2.97 or less. The intermediate layer (12) is formed of cellulose acylate or cellulose having a lower degree of substitution of acyl groups than the film substrate (11). The resin layer (13) has any one of a hydroxyl group, an amide structure and a pyrrolidone structure, and contains a polymer having a molecular weight of 30000 or more.)

1. An antifogging film having:

a film base material formed of a cellulose acylate having a degree of substitution with acyl groups in a range of 2.00 or more and 2.97 or less;

a 1 st layer formed of cellulose acylate or cellulose having a degree of substitution with acyl group smaller than that of the film substrate and provided on one surface of the film substrate; and

a 2 nd layer containing a resin component having a molecular weight of 30000 or more and provided on the surface opposite to the surface contacting the film substrate among the surfaces of the 1 st layer,

the resin component has any one of a hydroxyl group, an amide structure and a pyrrolidone structure.

2. The antifogging film of claim 1,

the resin component having the hydroxyl group is a cellulose derivative having the hydroxyl group and having a group that forms an ether bond with cellulose.

3. The antifogging film of claim 1,

the resin component having the pyrrolidone structure is a polymer having a vinylpyrrolidone structure.

4. The antifogging film of claim 3,

the resin component having the pyrrolidone structure is a polymer obtained by copolymerizing a vinylpyrrolidone compound and vinyl acetate and/or an acrylic acid derivative.

5. The antifogging film according to any one of claims 1 to 4,

the thickness of the 1 st layer is in the range of 0.5 μm or more and 20 μm or less.

Technical Field

The present invention relates to an antifogging film.

Background

Water drops are attached to the surfaces of mirrors in bathrooms and toiletries, refrigerated showcases, eyeglasses, ski goggles, swimming goggles, and the like due to dew condensation, thereby reducing visibility. Therefore, in order to prevent the visibility from being reduced, an antifogging film is used. Examples of a method for preventing the visibility of the antifogging film from being reduced include the following methods 1 and 2. Method 1 is a method for preventing formation of water droplets by an antifogging film having a film surface made of a water absorbent material, and water vapor is absorbed by the water absorbent material. Method 2 is a method of ensuring visibility by an antifogging film having a hydrophilic film surface. In this method 2, a water film is formed by wetting and spreading the adhering water with a low contact angle of a hydrophilic film surface. Even after the water absorbing capacity of the water absorbing material according to the method 1 is saturated, the visibility can be ensured in accordance with various environments in which the amount of water vapor to be water droplets is different by forming a water film on the film surface by the method 2.

In order to secure visibility in accordance with various environments, it is preferable to have an initial antifogging property as a function of preventing formation of water droplets instantaneously and a long-term antifogging property as a function of preventing formation of water droplets for a long time. Method 1 is associated with initial antifog properties and method 2 is associated with long-term antifog properties. As an antifogging film having an initial antifogging property and a long-term antifogging property, an antifogging film having a film surface formed of cellulose acylate with a specific contact angle and a specific ratio of acyl groups is disclosed (patent document 1). Further, an antifogging film is disclosed in which a hydrophilic agent-containing coating agent containing a surfactant and a hydrophilic polymer is coated on a film such as a polyester film (patent document 2). Even if the water-absorbing material has an initial antifogging property and a long-term antifogging property, water droplets may be temporarily formed and fogged after the water-absorbing material is saturated in water-absorbing capacity. This temporary fogging period is referred to as a "transition period". Patent document 2 aims to prevent fogging during a transient period.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-057370

Patent document 2: japanese Kohyo publication 2011-502064

Disclosure of Invention

Technical problem to be solved by the invention

The antifogging film of patent document 2 may be peeled off by dissolution of the coating agent with use, and has a problem in durability of the antifogging effect.

Accordingly, an object of the present invention is to provide an antifogging film having an initial antifogging property, a long-term antifogging property, and an antifogging property during a transition period in combination and having excellent durability of these antifogging properties.

Means for solving the technical problem

In order to solve the above problem, an antifogging film of the present invention includes a film base material, a 1 st layer and a 2 nd layer. The film base is formed of a cellulose acylate having a degree of substitution with acyl groups in the range of 2.00 to 2.97. The 1 st layer is formed of cellulose acylate or cellulose having a lower degree of substitution of acyl than the film substrate and is provided on one face of the film substrate. The 2 nd layer contains a resin component having a molecular weight of 30000 or more and is provided on the surface opposite to the surface contacting the film substrate among the surfaces of the 1 st layer. The resin component has any one of a hydroxyl group, an amide structure and a pyrrolidone structure.

The resin component having a hydroxyl group is preferably a cellulose derivative having a hydroxyl group and a group forming an ether bond with cellulose.

The resin component having a pyrrolidone structure is preferably a polymer having a vinylpyrrolidone structure.

The resin component having a pyrrolidone structure is preferably a polymer obtained by copolymerizing a vinylpyrrolidone compound and vinyl acetate and/or an acrylic acid derivative.

The thickness of the 1 st layer is preferably in the range of 0.5 μm or more and 20 μm or less.

Effects of the invention

The antifogging film of the present invention has an initial antifogging property, a long-term antifogging property, and an antifogging property during a transition period in combination, and is excellent in durability of these antifogging properties.

Drawings

Fig. 1 is a schematic cross-sectional view of an antifogging film.

Fig. 2 is a schematic view of an antifogging film production apparatus.

Fig. 3 is a schematic view of an antifogging film production apparatus.

Fig. 4 is an explanatory view for explaining an example of the use of the antifogging film.

Detailed Description

The antifogging film of the present invention includes a film substrate, a 1 st layer (hereinafter referred to as an intermediate layer), and a 2 nd layer (hereinafter referred to as a resin layer). As shown in fig. 1, the antifogging film 10 is a laminated film having a laminated structure in which a film base 11, an intermediate layer 12, and a resin layer 13 are laminated in this order. The shape of the antifogging film 10 is not limited, and may be a long shape or a sheet shape such as a rectangle. The antifogging film 10 may have other layers.

The thickness T10 of the antifogging film 10 is preferably in the range of 10 μm to 220 μm. More preferably 20 μm or more and 180 μm or less, and still more preferably 40 μm or more and 150 μm or less. When the thickness T10 is in the range of 10 μm to 220 μm, it is preferable because a layer including the film base 11, the intermediate layer 12, and the resin layer 13 can be formed and handling is easy when the antifogging film 10 is used by being attached to a mirror, a refrigerated showcase, or eyeglasses, goggles, or the like.

The film base 11 is a layer to be a base of the antifogging film 10, and functions as a support for supporting the intermediate layer 12 and the resin layer 13. The film substrate 11 is formed of cellulose acylate. The film substrate 11 absorbs water and releases water by temperature change and humidity change according to the equilibrium moisture content of the cellulose acylate. In the present embodiment, the cellulose acylate is a cellulose triacetate (hereinafter referred to as TAC), but is not limited to TAC, and may be a cellulose acylate other than TAC. In the film base material 11, a surface in contact with the intermediate layer 12 is one surface 11a, and the opposite surface is the other surface 11 b.

In cellulose acylate, a hydroxyl group of cellulose is esterified with a carboxylic acid and thus has an acyl group. It is known that the degree of substitution with acyl is the ratio of esterification of the hydroxyl groups of cellulose with carboxylic acid, i.e., the degree of substitution with acyl. The degree of acyl substitution of the cellulose acylate contained in the film base material 11 is in the range of 2.00 or more and 2.97 or less. The degree of substitution with acyl groups is within the above range, whereby deformation due to water absorption of the film base material 11 can be suppressed. The smaller the degree of substitution with acyl groups, the more the cellulose acylate absorbs water, and is therefore likely to be deformed by water absorption. Therefore, the degree of acyl substitution of the cellulose acylate contained in the film base material 11 is 2.00 or more. On the other hand, cellulose acylate having a degree of substitution with acyl group of more than 2.97 is difficult to synthesize. Therefore, the degree of substitution with acyl groups is 2.97 or less. The degree of acyl substitution of the cellulose acylate contained in the film base material 11 is preferably in the range of 2.40 to 2.95, and more preferably in the range of 2.70 to 2.95.

The acyl group of the cellulose acylate constituting the film base 11 is not particularly limited, and may be an acetyl group having 1 carbon atom, or an acyl group having 2 or more carbon atoms. The acyl group having 2 or more carbon atoms may be an aliphatic group or an aryl group, and examples thereof include an alkylcarbonyl ester, alkenylcarbonyl ester, aromatic carbonyl ester, and aromatic alkylcarbonyl ester of cellulose, and each of these may have a substituted group. Examples thereof include propionyl group, butyryl group, pentanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, isobutyryl group, tert-butyryl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthoyl group, and cinnamoyl group.

The acyl group of the cellulose acylate constituting the film substrate 11 may be only 1 kind, or 2 or more kinds, and preferably at least 1 kind is an acetyl group. The film base material 11 is a cellulose acylate having an acetyl group, and thus easily absorbs moisture, so that the moisture-containing effect and the like are further improved. Most preferred is a cellulose acylate in which all of the acyl groups are acetyl groups, that is, more preferred is a cellulose acetate.

The degree of acyl substitution can be determined by a conventional method. For example, the degree of acetylation (degree of acetyl substitution) may be according to ASTM: d-817-91 (test method for cellulose acetate, etc.) and calculation. Further, the degree of acylation (degree of substitution of acyl group) can be measured by distribution measurement by high performance liquid chromatography. As an example of this method, in the measurement of the degree of acetylation of cellulose acetate, a sample was dissolved in methylene chloride, and the degree of acetylation distribution was measured by using a column and Novapac-phenyl (manufactured by Waters corporation) by a linear gradient from a mixture of methanol and water (methanol: water mass ratio of 8: 1) to a mixture of methylene chloride and methanol (methylene chloride: methanol mass ratio of 9: 1) as an eluent, and was determined by comparing with a calibration curve using standard samples having different degrees of acetylation. These measurement methods can be determined by referring to the methods described in japanese patent application laid-open No. 2003-201301. In the case of collecting from the film substrate 11, additives are contained as follows, and therefore the measurement of the acetylation degree of cellulose acylate is preferably based on the measurement by high performance liquid chromatography.

The degree of substitution with acyl groups can be changed by adjusting the degree of substitution with hydroxyl groups of cellulose. Examples of the substitution of the hydroxyl group of the cellulose with the acyl group include a method using an acid anhydride or a mixed acid anhydride. Among them, the basic principle of the synthetic method of cellulose acetate is described in "wood chemistry" (KYORITSU SHUPPAN co., ltd., 1968, pages 180 to 190) edited in the right field and the like. A typical synthesis method is a liquid phase acetylation method using an acetic anhydride-acetic acid-sulfuric acid catalyst. Specifically, a cellulose raw material such as wood pulp or cotton linter is pretreated with an appropriate amount of acetic acid, and then put into an acetylation mixture which has been cooled in advance to perform acetic acid esterification, thereby synthesizing a complete cellulose acetate (the total of the degrees of substitution of acetyl groups at the 2-, 3-and 6-positions is almost 3). The acetylation mixture generally contains acetic acid as a solvent, acetic anhydride as an esterifying agent, and sulfuric acid as a catalyst. In stoichiometric amount, acetic anhydride is generally used in excess compared to the total amount of cellulose reacted with acetic anhydride and moisture present in the system, and thus hydrolysis of the excess acetic anhydride remaining in the system and neutralization of a part of the esterification catalyst are performed by a neutralizing agent (for example, carbonate, acetate or oxide of calcium, magnesium, iron, aluminum or zinc) after the acetylation reaction is completed. Then, the obtained complete cellulose acetate is saponified/matured in the presence of a small amount of an acetylation catalyst (usually, residual sulfuric acid) to obtain a cellulose acetate having a specific degree of substitution with acetyl groups and a specific degree of polymerization. When a specific cellulose acetate is obtained, the catalyst remaining in the system is completely neutralized with the neutralizing agent as described above or a cellulose acetate solution is put into water or dilute sulfuric acid without neutralization to separate the cellulose acetate, and the cellulose acetate is obtained by washing and stabilizing treatment.

As the additive, the film base material 11 may contain a plasticizer, an ultraviolet absorber, fine particles as a matting agent for preventing the sticking of the film base materials 11 to each other, and the like. As the additive, various known additives can be used. Examples of the plasticizer include triphenyl phosphate (TPP), diphenyl phosphate (BDP), ester derivatives of sugars, ester oligomers, and acrylic polymers. Any known ultraviolet absorber that exhibits ultraviolet absorbability can be used as the ultraviolet absorber, and examples thereof include those having a benzophenone skeleton, a benzotriazole skeleton, a triazine skeleton, and the like. The moisture content of the feature film substrate 11 and the thickness of the intermediate layer formed by the saponification treatment can be adjusted by adjusting the type and amount of the additive. As a result, moisture contained in the resin layer 13 is transferred to the intermediate layer 12 and the film base 11, so that the resin layer 13 is prevented from falling off, the durability of the antifogging effect is improved, and the water absorption capacity of the intermediate layer 12 and the film base 11 is increased, thereby improving the antifogging property. Preferable examples of the additive include an ester derivative and an ester oligomer of a sugar. The content of these additives is preferably in the range of 1 to 50, more preferably 2 to 30, where the mass of the cellulose acylate is 100.

The thickness T11 of the film base material 11 is in the range of 8 μm to 210 μm, preferably 30 μm to 200 μm. The thickness T11 is preferably in the range of 8 μm or more and 210 μm or less because it can be easily used as an antifogging film.

The intermediate layer 12 is a layer of cellulose acylate or cellulose having a smaller degree of substitution of acyl than the film substrate 11. In the present embodiment, as will be described later, the intermediate layer 12 is formed by subjecting one surface 14a of a TAC film 14 (see fig. 2) as the substrate film 11 to saponification treatment, and therefore the intermediate layer 12 is provided on the one surface 11a of the film substrate 11. The saponified TAC is formed on the intermediate layer 12.

The intermediate layer 12 is formed by saponification which is an alkali hydrolysis reaction of cellulose acylate, and an acyl group contained in TAC is converted into a hydroxyl group by a substitution reaction, thereby reducing the acyl group. That is, the degree of acyl substitution of the intermediate layer 12 is reduced to be smaller than that of the TAC film 14 (refer to fig. 2), that is, the film substrate 11. Further, the intermediate layer 12 containing cellulose acylate having more hydroxyl groups has higher water absorbency.

The degree of acyl substitution of the intermediate layer 12 is preferably 1.50 or less, although it also depends on the degree of acyl substitution of the film substrate 11. If the degree of substitution with acyl groups in the intermediate layer 12 is greater than 1.50, the proportion of acyl groups is large, and the water absorption may be insufficient. The lower limit of the acylation substitution degree of the intermediate layer 12 is 0. When the degree of substitution with acyl groups is 0, cellulose is shown, but the intermediate layer 12 may be formed of cellulose.

When the resin layer 13 on the surface on which the antifogging film 10 is formed contains moisture, the intermediate layer 12 is configured as described above, and the intermediate layer 12 in contact with the resin layer 13 absorbs water from the resin layer 13, thereby reducing the water content of the resin layer 13. This can prevent the resin layer 13 from dropping or falling off due to the resin layer 13 containing too much water.

The thickness T12 of the intermediate layer 12 is preferably in the range of 0.5 μm to 20 μm, more preferably 2 μm to 15 μm. When the thickness T12 is 0.5 μm or more, the effect of reducing the water content of the resin layer 13 by water absorption of the intermediate layer 12 can be more sufficiently exhibited than the case of being thinner than 0.5 μm, and therefore, it is preferable. On the other hand, it is not easy to form the intermediate layer 12 thicker than 20 μm. In the present embodiment, the thickness T12 is determined by the following method. A sample sampled from a material including the film substrate 11 and the intermediate layer 12 obtained by subjecting the film substrate 11 to saponification treatment was immersed in dichloromethane for 24 hours. The sample that did not dissolve in the immersion was dried, and the thickness of the dried sample was measured 3 times. The average of the 3 measurements was taken as thickness T12.

The resin layer 13 (see fig. 1) contains a resin component having a molecular weight of 30000 or more, and the resin component is a layer having any one of a hydroxyl group, an amide structure, and a pyrrolidone structure. The resin layer 13 is formed on the one surface 12a of the intermediate layer 12, and constitutes the outermost layer of the antifogging film 10. The resin layer 13 is formed of a hydrophilic polymer. Therefore, the resin layer 13 absorbs water vapor that may be water droplets near the surface of the antifogging film 10, and has initial antifogging properties. Also, immediately after the initial antifogging saturation, a water film is formed, preventing water droplets from adhering during the transition. Moisture moves from the resin layer 13 to the intermediate layer 12, and long-term antifogging property is exhibited. Further, the resin layer 13 has affinity with the intermediate layer 12, and thus, for example, the resin layer 13 is inhibited from falling off or falling off due to moisture. Furthermore, the moisture contained in the resin layer 13 moves to the intermediate layer 12, and the molecular weight is 30000 or more, so that the moisture of the resin layer 13 can be kept low, and therefore, the moisture is not likely to flow down together with water. Further, the resin layer 13 is formed of a specific hydrophilic polymer and the solubility in water is suppressed, so that it is less likely to fall off due to moisture. Therefore, the resin layer 13 has durability in antifogging property.

The resin layer 13 has any one of a hydroxyl group, an amide structure, and a pyrrolidone structure, and contains a polymer having a molecular weight of 30000 or more. In the present specification, the amide structure refers to a structure represented by — C (═ O) -NH-. The pyrrolidone structure is represented by the following formula (1).

[ chemical formula 1]

The term "polymer having the group or structure" as used herein means a polymer having a main chain, a side chain, a graft polymer chain, or the like, as long as the polymer contains the group or structure.

Examples of the polymer having a hydroxyl group include celluloses, polyvinyl alcohols, hydroxyl group-containing acrylic polymers, and the like. Specific examples thereof include celluloses such as cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose (HEC), hydroxymethyl cellulose (CMC), and hydroxypropyl cellulose (HPC); polyvinyl alcohols such as polyvinyl alcohol, polyvinyl alcohol obtained by partially saponifying polyvinyl acetate, and polyvinyl acetate copolymer; hydroxyl group-containing acrylic polymers such as polymers or copolymers of acrylic acids such as hydroxyethyl acrylate.

Among them, cellulose derivatives having a hydroxyl group and a group forming an ether bond with cellulose are preferable. Specific examples thereof include methyl cellulose, ethyl cellulose, hydroxyethyl cellulose (HEC), hydroxymethyl cellulose (CMC), and hydroxypropyl cellulose (HPC). The cellulose has a high ratio of hydroxyl groups per cellulose structural unit, and therefore easily forms a water film on the surface, and has a hydrocarbon group forming an ether bond with the cellulose, thereby suppressing the solubility in water of the cellulose derivative itself, improving the initial antifogging property, and being excellent in the durability of the antifogging property. Among them, hydroxyethyl cellulose (HEC) or hydroxypropyl cellulose (HPC) is preferable. As the Hydroxyethylcellulose (HEC), an aqueous solution or a powder may be used.

Examples of the polymer having an amide structure include polyamides, polyacrylamides, and the like, and specifically, polyamides such as nylon 6 obtained by ring-opening polymerization of caprolactam, nylon 66 obtained by polycondensation of hexamethylenediamine and adipic acid; polyacrylamides such as acrylamide polymers and copolymers of acrylamide and other acrylic acid derivatives. Among them, an acrylamide resin obtained by copolymerizing acrylamide having high hydrophilicity with another acrylic acid derivative which suppresses solubility in water is preferable because the durability of the antifogging effect is good. In the case of an acrylamide resin obtained by copolymerizing an acrylic acid derivative and acrylamide, which suppresses the solubility in water, acrylamide is preferably in the range of 40 parts by mass or more and 95 parts by mass or less.

Specific examples of the polymer having a pyrrolidone structure include polymers containing a vinylpyrrolidone compound such as N-vinyl-2-pyrrolidone and N-vinyl ethyl-2-pyrrolidone. Among them, polymers having a vinylpyrrolidone structure are preferable. The polymer having a vinylpyrrolidone structure may be a polymer obtained by polymerizing a vinylpyrrolidone compound (for example, the above-mentioned N-vinyl-2-pyrrolidone or N-vinyl ethyl-2-pyrrolidone) as a monomer, or may be a copolymer of a vinylpyrrolidone compound and another monomer. Among them, a polymer obtained by copolymerizing a vinylpyrrolidone compound and at least 1 compound selected from the group consisting of vinyl acetate and acrylic acid derivatives is preferable. The acrylic acid derivative to be copolymerized may be any acrylic acid derivative that is copolymerized with a vinylpyrrolidone compound to form a polymer, and specific examples thereof include acrylic acid; methacrylic acid; alkyl esters of acrylic acid such as methyl acrylate and ethyl acrylate; alkyl esters of methacrylic acid such as methyl methacrylate and ethyl methacrylate. The polyvinylpyrrolidone having a pyrrolidone structure has high affinity with the cellulose acylate or cellulose of the intermediate layer 12, and is excellent in durability of the antifogging effect. Further, a polymer having a pyrrolidone structure with high hydrophilicity and copolymerized with vinyl acetate or another acrylic acid derivative which can suppress solubility in water is also preferable, and a copolymer of N-vinyl-2-pyrrolidone and vinyl acetate is particularly preferable. In the case of a polymer having a pyrrolidone structure copolymerized with vinyl acetate or another acrylic acid derivative which suppresses solubility in water, the content of the pyrrolidone structure is preferably in the range of 40 parts by mass or more and 95 parts by mass or less. The resin layer 13 may contain 1 kind of the above-mentioned polymer, or 2 or more kinds of the above-mentioned polymer may be contained in combination.

In the resin layer 13, it is also preferable to further add an additive that improves the interaction between the polymers to the polymer having any one of a hydroxyl group, an amide structure, and a pyrrolidone structure. Examples of such a method include a method of adding an additive that bonds to or interacts with a hydrophilic group such as a hydroxyl group, and a method of increasing the interaction between ionic groups by inhibiting ionic dissociation or the like by adding an acid (in the case where a polymer has a carboxyl group or other ionic group). Specifically, there is a method of adding an acid such as citric acid to a polymer having a hydroxyl group and a carboxyl group (e.g., hydroxymethylcellulose). In this method, the water film formability of the hydroxyl group-based surface is excellent, and the durability of the antifogging property is excellent based on the interaction of the carboxyl group of the polymer and the citric acid component.

The molecular weight of the polymer contained in the resin layer 13 is 30000 or more. The molecular weight is a number average molecular weight determined by GPC in a polymer that can be determined by Gel Permeation Chromatography (GPC, Gel polymerization Chromatography), and a viscosity average molecular weight determined from a capillary viscosity measurement value in a polymer for which it is difficult to determine the molecular weight by GPC (for example, polyvinylpyrrolidone or the like). The molecular weight is preferably in the range of 30000 or more and 2000000 or less. More preferably 35000 or more and 1800000 or less, and particularly preferably 40000 or more and 1500000 or less. When the molecular weight of the polymer is in the range of 30000 or more and 2000000 or less, the moisture contained in the resin layer 13 moves to the intermediate layer 12 and the moisture in the resin layer 13 is kept low, and as a result, the water is less likely to fall off together with the water, and therefore, the durability of antifogging property is excellent, and thus, preferable.

The thickness T13 (see fig. 1) of the resin layer 13 is preferably in the range of 1 μm to 20 μm. More preferably, it is in the range of 2 to 18 μm, and particularly preferably in the range of 5 to 15 μm. The thickness T13 (see fig. 1) is preferably in the range of 1 μm to 20 μm, because the effect of the long-term antifogging property of the resin layer 13 can be sufficiently exerted and the antifogging property of the antifogging film 10 can be sufficiently exerted. In addition, moisture is preferably easy to permeate into the intermediate layer 12, and the water absorbing effect of the intermediate layer 12 can be sufficiently exerted. When the thickness T13 is greater than 20 μm, the resin layer 13 may flow down or fall off due to moisture, and the thickness T13 may be reduced to the above range. At this time, the antifogging film 10 of the present invention exerts its effect, and exhibits antifogging properties in the initial antifogging property, the long-term antifogging property, and the transient period.

In the present embodiment, the intermediate layer 12 is formed by the intermediate layer forming device 16. The intermediate layer forming apparatus 16 shown in fig. 2 is an apparatus for continuously manufacturing an antifogging film material 18 including a film base material 11 and an intermediate layer 12 as a part of an antifogging film 10.

The intermediate layer forming apparatus 16 includes a feeder 20, a saponification unit 22, a drying device 24, and a winder 26 in this order from the upstream side in the conveying direction of the antifogging film material 18. The intermediate layer forming apparatus 16 is further provided with a roller 36. The roller 36 is provided in plural, but only two are illustrated in fig. 2. The roller 36 supports the TAC film 14 or the antifogging film material 18 from below with a peripheral surface thereof, and rotates around a rotation axis to convey the TAC film 14 or the antifogging film material 18.

The TAC film 14 is manufactured by a film forming apparatus (not shown) using a known solution film forming method. Specifically, in the film forming apparatus, a polymer solution containing TAC (hereinafter, referred to as dope) is cast onto a support to form a casting film, and the casting film is peeled from the support and dried to form a long film. The dope is prepared from TAC, additives and solvents added according to needs.

The feeder 20 is for continuously feeding out a long TAC film 14. The TAC film 14 is set to the feeding machine 20 in a state of being wound around the winding core 28 in a roll shape, and the winding core 28 is rotated, whereby the TAC film 14 is continuously fed out.

The saponification unit 22 is used to form the antifogging film material 18 by continuously saponifying the TAC film 14. The saponification unit 22 includes a coating device 30, an infrared heater 32, and a cleaning device 34.

The coating device 30 is used to coat the saponification liquid 38 on one surface 14a of the TAC film 14. The application device 30 continuously discharges the supplied saponification liquid 38 from the discharge port 30a facing the one surface 14 a. The saponification liquid 38 is continuously discharged from the TAC film 14 by the coating device 30, and the saponification liquid 38 is continuously coated on the one surface 14 a. As a method of the saponification treatment, a method of applying the saponification liquid 38 by coating as in the present embodiment, a method of applying by dipping, and the like can be cited. A layer formed by subjecting the TAC film 14 (refer to fig. 2) to saponification treatment is the intermediate layer 12 (refer to fig. 1), and the remaining part of the TAC film that is not saponified by this saponification treatment is the film substrate 11 (refer to fig. 1). Thus, the film substrate 11 contains no saponified TAC and the intermediate layer 12 contains saponified TAC.

The saponification liquid 38 is used to saponify one surface of the TAC film 14 to form the intermediate layer 12 (refer to fig. 1), and contains alkali. In the present embodiment, the base is potassium hydroxide (KOH), but is not limited thereto, and sodium hydroxide (NaOH) may be used instead of KOH. In this example, the saponification solution 38 contains a solvent in addition to the alkali. As the solvent, water and an organic solvent are included. The organic solvent may use 1 or 2 or more selected from the group consisting of alcohols, ethers, amides, and sulfoxides. The alcohol is preferably an alcohol having 2 to 8 carbon atoms. Examples of the alcohol having 2 to 8 carbon atoms include ethanol, isopropanol, 1-propanol, 1-butanol, hexanol, ethylene glycol, glycerol, propylene glycol, butylene glycol, pentaerythritol, and the like. Of these, isopropyl alcohol is particularly preferable, and isopropyl alcohol is also used in the present embodiment. Examples of the ethers include diethyl ether, diethylene glycol, dipropylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and propylene glycol monomethyl ether. Examples of the amides include N, N-dimethylformamide and dimethylacetamide. Examples of the sulfoxide include dimethyl sulfoxide and the like.

The organic solvent has an action of promoting the penetration of the alkali into the TAC film 14 in addition to the action as a solvent. In this example, an alcohol is used, and the saponification liquid 38 is applied to apply an alkali and the alcohol. The method is not limited to this embodiment, and for example, a method of sequentially applying an alcohol and an aqueous alkali solution may be used. In this case, it is more preferable to apply the saponification liquid after applying the alcohol.

Alcohol in every 1m of one side 14a²An area of at least 17g, i.e. 17g/m²The coating amount is as above to coat one surface 14 a. The amount of alcohol to be applied is preferably 17g/m²Above and 39.6g/m²More preferably in the range of 22g/m²Above and 39.6g/m²More preferably, it is in the range of 33.4g/m²Above and 39.6g/m²Within the following ranges.

Alkali in 1m per one side 14a²An area of at least 0.3g, i.e. 0.3g/m²The coating amount is as above to coat one surface 14 a. Thereby, the alkali reliably and quickly penetrates into the film substrate 11. The amount of the alcohol to be added is preferably 0.3g/m²Above and 1.3g/m²More preferably in the range of 0.6g/m²Above and 1.3g/m²More preferably, it is in the range of 0.7g/m²Above and 1.3g/m²Within the following ranges.

The infrared heater 32 is used to maintain a predetermined temperature range for a predetermined time by heating the TAC film 14. The infrared heater 32 is provided in a state where an emitting surface from which infrared rays are emitted faces the TAC film 14 being conveyed. The infrared heater 32 may be disposed so as to face the one surface 14a on which the coating film 40 formed of the saponification liquid 38 is formed, but it is preferable to be disposed so as to face the other surface 14b, which is the film surface opposite to the one surface 14a, as in the present embodiment shown in fig. 2, because the alkali penetrates more reliably and more efficiently from the one surface 14a side.

Instead of the infrared heater 32 or in addition to the infrared heater 32, a blowing type air blowing device that blows gas that heats the TAC film 14, a chamber type air blowing device that surrounds a transport path of the TAC film 14 with a chamber and supplies heated gas to the chamber, or the like may be used.

In order to improve the initial antifogging property, one surface 14a is held at a temperature of 40 ℃ to 80 ℃ for a time of 20 seconds to 120 seconds by heating with the infrared heater 32. By keeping at 40 ℃ or higher, saponification proceeds rapidly, and the intermediate layer 12 having a larger thickness T12 is formed, as compared with the case of lower than 40 ℃, so that the initial antifogging property is reliably exhibited. By keeping at 80 ℃ or lower, the evaporation of alcohol is reliably suppressed and the intermediate layer 12 is reliably formed, as compared with the case of higher than 80 ℃. The temperature to be maintained is more preferably in the range of 40 ℃ to 70 ℃, and still more preferably in the range of 50 ℃ to 70 ℃.

The time for holding within the temperature range is set to 20 seconds or more and 120 seconds or less. By setting to 20 seconds or more, the saponification proceeds rapidly, and the intermediate layer 12 having a larger thickness T12 (refer to fig. 1) is formed, as compared with the case of less than 20 seconds, and therefore the water supply ability is more clearly exhibited. By setting the time to 120 seconds or less, a saponified layer having an appropriate thickness can be formed. The time for holding within the temperature range is more preferably 30 seconds or more and 100 seconds or less, and still more preferably 30 seconds or more and 50 seconds or less.

The cleaning device 34 is used to stop saponification by cleaning the TAC film 14. The cleaning device 34 has a spray type cleaning machine that sprays water to the side of the one surface 14a on which the coating film 40 is formed. By spraying water, the alkali can be quickly removed from the TAC film 14.

The TAC film 14 passing through the cleaning device 34 is formed with the intermediate layer 12, and is dried by guiding the TAC film 14 to the drying device 24. In the present embodiment, a chamber type drying apparatus is used as the drying apparatus, in which the transport path is surrounded by a chamber and heated gas is supplied to the chamber, but the drying apparatus is not particularly limited. By this drying, the contained water is evaporated, and a long antifogging film material 18 is obtained. The antifogging film material 18 is guided to the winder 26 and wound in a roll shape around the provided winding core 42. After being wound by the winding core 42, the sheet is sent to a resin layer forming apparatus 44 (see fig. 3). In the resin layer forming device 44 (refer to fig. 3), the antifogging film material 18 wound around the winding core 42 is supplied, and the resin layer 13 is formed on the one surface 12a of the antifogging film material 18, thereby manufacturing the antifogging film 10.

The resin layer 13 (refer to fig. 1) is provided on one face 12a (refer to fig. 1) of the faces of the intermediate layer 12 opposite to the other face 12b (refer to fig. 1) contacting the film substrate 11. As a method for forming the resin layer 13, any method can be applied as long as it can form the one surface 12a without impairing the functions of the film base 11 and/or the intermediate layer 12. Therefore, for example, the resin layer 13 may be formed by applying the coating composition 41 containing the polymer forming the resin layer 13 on the one surface 12a, or may be formed by attaching a film formed of the coating composition 41 or the like to the one surface 12 a. The resin layer 13 can be formed well without risk of peeling or the like from the intermediate layer 12. This is considered to be because the resin layer 13 and the intermediate layer 12 have affinity and are firmly joined together.

In the present embodiment, the resin layer 13 is formed by applying the coating composition 41 prepared for coating on the one surface 12 a. The resin layer 13 can be produced by a resin layer forming apparatus 44 shown in fig. 3. The resin layer forming device 44 shown in fig. 3 is a device for continuously producing the antifogging film 10 by forming the resin layer 13 on the antifogging film material 18 (see fig. 2). The intermediate layer forming device 16 for producing the antifogging film material 18 and the resin layer forming device 44 for producing the antifogging film 10 by forming the resin layer 13 on the antifogging film material 18 may be separately used, for example, for batch production, or may be connected to each other and continuously used to produce the antifogging film 10.

Further, depending on the final product to be produced from the antifogging film 10, the coating composition 41 can be applied to a material obtained by cutting the long antifogging film material 18 into a sheet shape by a commonly used method. Examples of the above method include bar coating, die coating, and spin coating. Further, the coating composition 41 can be applied to the material cut into a sheet shape by a spray coating method, a method in which the coating composition 41 is dipped in a cloth and applied to the antifogging film 10 and then dried, or a method in which the dried cloth is uniformly spread.

The resin layer forming device 44 includes a feeder 46, a resin layer forming unit 48, a drying device 49, and a winder 51 in this order from the upstream side in the conveying direction of the antifogging film 10.

The feeder 46 is used to continuously feed the long antifogging film material 18. The antifogging film material 18 is set to the feeding device 46 in a state of being wound around the winding core 42 in a roll shape, and the winding core 42 is rotated, whereby the antifogging film material 18 is continuously fed.

The resin layer forming unit 48 is for continuously forming the resin layer 13 on the one surface 12a of the antifogging film material 18. The resin layer forming unit 48 includes a coating device 50, an infrared heater 52, and a roller 54. The roller 54 is provided in plurality, but only one is illustrated in fig. 3. The roller 54 supports the antifogging film material 18 from below on the circumferential surface and rotates around the rotation axis, thereby conveying the antifogging film material 18.

The coating device 50 is used to coat the coating composition 41 for forming the resin layer 13 on the one surface 12a of the antifogging film material 18 on the intermediate layer 12 side. The coating device 50 continuously discharges the supplied coating composition 41 from the discharge port 50a facing the one surface 12 a. In fig. 3, the coating composition 41 is described as "composition". The coating composition 41 is continuously discharged onto the carried antifogging film material 18 by the coating apparatus 50, and the coating composition 41 can be continuously coated on the one surface 12 a.

The infrared heater 52 is used to heat the antifogging film material 18 to cure the composition contained in the coating composition 41. The infrared heater 52 is provided so that an emission surface from which infrared rays are emitted faces the antifogging film material 18 being conveyed. The infrared heater 52 may be disposed so as to face the one surface 12a on which the coating film 56 formed of the coating composition 41 is formed, or may be disposed so as to face the other surface 11b of the film base 11 as in the present embodiment shown in fig. 3, the other surface 11b being a film surface on the opposite side from the one surface 12 a.

Instead of the infrared heater 52 or in addition to the infrared heater 52, an air blowing device, a chamber type air blowing device, or the like may be used for the antifogging film material 18, as described above with reference to the intermediate layer forming device 16 (see fig. 2).

The resin layer 13 is formed on the antifogging film material 18 passing through the infrared heater 52, and the antifogging film material 18 is guided to the drying device 49 to be dried. As the drying device, in the present embodiment, as described above, a chamber type drying device is used, but is not particularly limited. By this drying, the solvent contained therein is evaporated, and a long antifogging film 10 is obtained. The antifogging film 10 is guided to the winder 51 and wound in a roll shape around the winding core 58. The order of forming the intermediate layer 12 and the resin layer 13 on the film base 11 is not limited to this. For example, the film substrate 11, the intermediate layer 12, and the resin layer 13 may be formed as separate films, the intermediate layer 12 may be attached to the resin layer 13, and then the film substrate 11 may be attached, or the film substrate 11, the intermediate layer 12, and the resin layer 13 may be simultaneously laminated.

As shown in fig. 4, an antifogging film bonding glass 60 as an example of a method of using the antifogging film 10 of the present embodiment is bonded to one surface of a plate glass 62 after the antifogging film 10 is cut out via an adhesive layer 64. Examples of the adhesive layer 64 include an acrylic adhesive, a silicone adhesive, and a urethane adhesive, and in the present embodiment, an acrylic adhesive is used. The sheet glass 62 is so-called float glass having a thickness of 5 mm. For example, when the glass is used for a mirror in a bathroom, the mirror can exhibit a sufficient antifogging effect against various environments required for antifogging.

As described above, the antifogging film 10 of the present invention is configured by combining the film base 11, the intermediate layer 12, and the resin layer 13, and therefore functions as the antifogging film 10 as follows. That is, since the film base material 11 is formed of a specific cellulose acylate, it is less deformed while absorbing and releasing water, and is excellent as a support for other layers. The intermediate layer 12 is formed of a specific cellulose acylate or cellulose, and therefore exhibits excellent water absorption. Furthermore, since the antifogging film 10 composed of these layers interacts with the film base 11 and the resin layer 13 that contact the intermediate layer 12, the durability is excellent. Since the resin layer 13 is formed of a hydrophilic polymer having a specific molecular weight, the intermediate layer 12 and the film base 11 suppress the dripping due to the excessive moisture content, and have durability of long-term antifogging properties. Therefore, the antifogging film 10 is excellent in initial antifogging property based on water absorption, has antifogging property during transition by the resin layer 13, and excellent long-term antifogging property has durability, and thus is excellent in antifogging property. Each layer is firmly held, and the antifogging film 10 itself is less deformed, and for example, the resin layer 13 can be prevented from coming off due to the deformation, and durability is provided.

Further, since the resin layer 13 includes a polymer having a vinylpyrrolidone structure, a polymer having an amide structure, or a specific cellulose derivative, both of the hydrophilic property and the strength of the resin layer 13 are excellent. Further, by containing a copolymer of a vinylpyrrolidone compound and a specific compound in the resin layer 13, the hydrophilic property and strength are particularly improved.

When the thickness of the intermediate layer 12 is within the above-specified range, the antifogging film 10 can exhibit more accurate antifogging performance under various environments when the above-described 3 layers are combined, and thus it is preferable.

In the antifogging film 10, the combination of the thicknesses of the respective layers depending on the application is selected depending on the material of the respective layers, and can be selected depending on the antifogging property or the antifogging film handleability depending on the application, for example, as follows: a combination of 38 μm for the film base 11, 2 μm for the intermediate layer 12 and 5 μm for the resin layer 13 is used for attachment to a mirror requiring a toilet table easy to handle, a combination of 115 μm for the film base 11, 10 μm for the intermediate layer 12 and 10 μm for the resin layer 13 is used for attachment to a bathroom mirror requiring antifogging property, and a combination of 180 μm for the film base 11, 15 μm for the intermediate layer 12 and 10 μm for the resin layer 13 is used for glasses or goggles requiring strength. When the cellulose derivative is used for the resin layer 13 in order to be attached to a refrigerated showcase, the antifogging performance in refrigeration is good, and thus it is preferable. The freeze antifogging property means an antifogging property in a low-temperature environment such as a freezer as described later.

Examples of the present invention and comparative examples to the present invention are given below.