JP2525651B2 - Anti-fog sheet and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sheet having an antifogging property and a method for producing the same, and particularly to an antifogging sheet having a good surface condition and maintaining the antifogging property for a long period of time. And a manufacturing method thereof.

[Problems to be Solved by Prior Art and Invention]

When the windows and side mirrors of automobiles, mirrors and windows of bathhouses, etc. are exposed to moisture, the surface becomes cloudy,
It was inconvenient to wipe off frequently. Therefore, various attempts have been made to impart antifogging properties to the surface of these articles.

Conventionally, as an anti-fogging layer that imparts anti-fogging property to the surface of an article, (a) an anti-fogging property obtained by kneading a surfactant into a resin, (b) an inorganic salt such as colloidal silica or phosphite To extend the antifogging life, and (c) to make the surface hydrophilic by modifying the polymer such as saponification of acetylcellulose.

However, the antifogging layers (a) and (b) have a problem that the antifogging property has a short life due to early leaching of the surfactant. Furthermore, the above-mentioned (c) antifogging layer has a poor film strength when wet, and there is a problem that it is scratched during application and the antifogging property deteriorates.

As a means for solving the above problems of the prior art, the present inventors previously had a support film and an antifogging layer, the antifogging layer is a polymer and a hydrophilic monomer crosslinked by electron beam irradiation. We have proposed an antifogging sheet characterized by the following (Japanese Patent Application No. 62-114348).

By the way, recently, there has been a need for an antifogging sheet having a relatively thick antifogging layer (hydrophilic film). This is because there is a demand for further improvement of the antifogging property and holding for a long period of time. However, when an attempt is made to form a thick antifogging layer with a solvent-containing coating solution, the surface of the antifogging layer becomes rough,
It was found to be unsuitable as an anti-fog sheet to be attached to a mirror or window.

Therefore, it is an object of the present invention to provide an antifogging sheet having a thick hydrophilic film for maintaining the antifogging property for a long period of time.

Another object of the present invention is to provide a method for producing such an anti-fog sheet.

[Means for solving the problem]

As a result of intensive studies in view of the above objects, the present inventors have applied a hydrophilic film component as a non-solvent-based coating liquid on a support film, and crosslink by electron beam irradiation to have a good surface state. The inventors have found that a thick hydrophilic film can be obtained, and conceived the present invention.

That is, in the antifogging sheet of the present invention, a hydrophilic film containing a polymer, a hydrophilic monomer, and a surfactant and crosslinked by electron beam irradiation and having a thickness of more than 30 μm is formed on the surface of the support film. It is characterized by

Further, the method for producing an antifogging sheet of the present invention, a non-solvent type coating solution containing a polymer, a hydrophilic monomer and a surfactant is prepared, and the thickness after crosslinking the coating solution on a support film is 30 μm. It is characterized in that it is applied so as to exceed the above and crosslinked by electron beam irradiation.

 The present invention will be described in detail below.

Supporting film As the supporting film, various materials can be used depending on the application as long as they have sufficient mechanical strength and transparency to support the hydrophilic film. Specific examples include polyester films such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, polyamides such as nylon, polycarbonate, polyacrylate, polystyrene, and films of synthetic resins such as polyvinyl chloride. These can be used by laminating if necessary.

The support film may be colored in various colors as needed. As the colorant, disperse dyes are preferable, and disperse dyes such as monoazo, bisazo, anthraquinone, nitro, styryl, methine, allylene, benzimidazole, aminonaphthylamide, nactoquinone imide and coumarin derivative can be used.

The hydrophilic film in the present invention basically comprises a polymer in which a hydrophilic monomer or the like is crosslinked by electron beam irradiation and a surfactant is contained therein. Specific combinations include (a) polymer + hydrophilic monomer + surfactant, (b) polymer + hydrophilic monomer + crosslinking monomer + surfactant, (c) polymer + hydrophilic crosslinking monomer + surfactant (D) polymer + hydrophilic monomer + hydrophilic cross-linkable monomer + surfactant. In all combinations of the above, the polymer may be either a functional polymer or a non-functional polymer.

As the non-functional polymer, polyacrylic acid alkyl ester, polymethacrylic acid alkyl ester, polyurethane, polyester, polyamide, polyvinyl acetate, polyvinyl chloride, polystyrene, polyacrylonitrile,
Polyvinylpyrrolidone or the like can be used.

In order to improve the compatibility with the hydrophilic polymer, a hydrophilic group may be introduced into the non-functional polymer in advance. This is a copolymer with a monomer having a hydrophilic group (hydrophilic monomer) described later. The ratio of the hydrophilic monomer to the non-functional polymer is 50 mol% or less, and if it exceeds this ratio, the water resistance of the obtained film decreases.

In addition, polyvinyl alcohol derivatives such as partially saponified polyvinyl alcohol, polyvinyl butyral and polyvinyl acetal, and cellulose derivatives such as nitrocellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate and hydroxypropyl cellulose can also be used. .

On the other hand, the functional polymer is a polymer having a functional group which causes a crosslinking reaction by ionizing radiation, and examples of the functional group include the following.

Allyl group -CH ₂ -CH = CH ₂ It is desirable that the functional group is one in the molecular weight of 300 to 10,000, and if the ratio is less than 1 per 10,000 molecular weight, there is almost no crosslinking effect by the functional group, and if it exceeds 1 in 300 molecular weight, the crosslink density is high. Is too high.

As the functional polymer, urethane acrylate, polyester acrylate, epoxy acrylate, etc., or acrylic acid chloride or 2-hydroxyethyl acrylate and diisocyanate at the hydroxyl group of the copolymer of alkyl acrylate and 2-hydroxyethyl acrylate. Of 1: 1 adduct to introduce an acryloyl group, a copolymer of alkyl acrylate and acrylic acid with glycidyl methacrylate added to the carboxyl group, and polyvinyl butyral residue Acrylic acid chloride or acrylic acid-2 for hydroxyl group
-A 1: 1 addition product of hydroxyethyl and diisocyanate can be used.

The above-mentioned polymer may be in the form of an oligomer, but the molecular weight thereof is preferably 1,000 to 300,000 (weight average) from the viewpoint of film-forming property.

The hydrophilic monomer is a monomer containing a hydrophilic group such as a hydroxyl group, a carboxyl group (metal salt), an amide group, an imide group, a sulfone group, an ammonium group, and a phosphoric acid group, such as 2-hydroxyethyl acrylate and methacrylic acid. 2-hydroxyethyl, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylic acid, methacrylic acid, metal acrylate, metal methacrylate, acrylic acid dimer, acrylamide, methacrylamide, dimethylaminopropyl acrylamide, dimethyl Aminopropylmethacrylamide, N-acryloylmorpholine, N-methacryloylmorpholine, N-methylolacrylamide, N-methylolmethacrylamide, t-butylacrylamide, t-butylmethacrylamide, N- Butoxy methyl acrylamide, N- ethoxymethyl acrylamide, N-n-butoxy acrylamide, N, N- dimethylacrylamide, N, N- dimethylaminopropyl acrylamide, N, N
-Dimethylaminopropyl methacrylamide, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, glycerol monomethacrylate, 2-acrylamido-2-methylpropanesulfonic acid, methacrylamidopropyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, mono (2-meta Examples include chloroxyethyl) acid phosphate and the like.

The crosslinkable monomer is a monomer having two or more groups such as an acryloyl group, a methacryloyl group, an allyl group, and an epoxy group, which easily become radicals by electron beam irradiation, and crosslinks with both the skeleton polymer and the hydrophilic monomer. It improves the overall crosslink density, increases the film strength, and prevents unreacted hydrophilic monomers from remaining. As such a crosslinkable monomer, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate,
Glycidyl methacrylate, neopentyl glycol dimethacrylate, tetraethylene glycol dimethacrylate, 2,2-bis [4- (acryloxydiethoxy)
Phenyl] propane, 2,2-bis [4- (methacryloxydiethoxy) phenyl] propane, 2,2-bis [4-
(Acryloxypolyethoxy) phenyl] propane, 2,
Bifunctional monomers such as 2-bis [4- (methacryloxypolyethoxy) phenyl] propane, trifunctional monomers such as trimethylolpropane trimethacrylate, and other polyfunctional monomers such as tetramethylolmethane tetraacrylate and dipentaerythritol hexaacrylate. Is mentioned.

Hydrophilic crosslinkable monomers include hydroxyl groups, carboxyl groups (metal salts), amide groups, imide groups, sulfonic acid groups (metal salts), ammonium groups, phosphoric acid groups and other hydrophilic groups, and acryloyl groups, methacryloyl groups, allyl groups, It is a monomer having two or more crosslinkable functional groups that easily become radicals by electron beam irradiation such as epoxy groups.

As such a hydrophilic crosslinkable monomer, for example,
Those having a hydroxyl group such as glycerol di (meth) acrylate, glycerol methacrylate acrylate, ethylene glycol, diglycidyl ether di (meth) acrylate, polyethylene glycol / diglycidyl ether di (meth) acrylate, polypropylene glycol / diglycidyl ether di (meth) ) Acrylate,
Diol diesters such as neopentyl glycol diglycidyl ether di (meth) acrylate, glycerin diglycidyl ether di (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, trimethylolpropane triglycidyl ether di (meth) acrylate Glycidyl ether and acrylic acid 1:
2 adduct, pentaerythritol mono (meth) acrylate, pentaerythritol di (meth) acrylate,
Pentaerythritol tri (meth) acrylate, dipentaerythritol mono (meth) acrylate, dipentaerythritol di (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) ) Pentaerythritol derivatives such as acrylate, methylenebis (meth) acrylamide, acrylamide / glyoxal adduct, acrylamide / methyloethylene urea condensate, 1,3,5-triacryloylhexahydro s-triazine, N, N-diallyl acrylamide, acrylamide / Methylol melamine condensate, acrylamide / methylol triazone condensate, acrylamide / methylol hydantoin condensate,
There are acrylamide derivatives such as acrylamide / methylol urea and N, N-diallyl acrylamide.

The hydrophilic film used in the present invention may also contain a surfactant. The surfactant has a function of imparting antifogging property (condensation preventing property) by gradually leaching from the hydrophilic film to the surface. Any anionic, nonionic or cationic surfactant can be used as long as it has good compatibility with the composition comprising the above components constituting the hydrophilic layer.

Examples of anionic surfactants include fatty acid salts, alkyl sulfate salts, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinate esters, alkyl phosphate esters, naphthalene sulfonic acid-formalin condensates, and polyoxyethylene. Alkyl sulfates, etc., and nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine Glycerin fatty acid esters, oxyethylene-oxypropylene block polymers, etc., and cationic surfactants include alkylamines and quaternary ammonium. There is salt, and the like.

When forming the hydrophilic film used in the present invention, the polymer 10
The hydrophilic monomer is added in an amount of 5 to 300 parts by weight per 0 parts by weight. If the amount is less than 5 parts by weight, sufficient hydrophilicity is not imparted, and conversely, if the amount exceeds 300 parts by weight, the water resistance of the film decreases.
The preferable content of the hydrophilic monomer is 20 to 250 parts by weight.

The crosslinkable monomer is 1 to 300 parts by weight per 100 parts by weight of the polymer. If it is less than 1 part by weight, the unreacted hydrophilic monomer is insufficiently crosslinked, and if it exceeds 300 parts by weight, the crosslinking density of the entire membrane becomes too high. Particularly when the polymer has no functional group, the content of the crosslinkable monomer is preferably 5 to 300 parts by weight, more preferably 5 to 200 parts by weight. When the polymer has a functional group, the content of the crosslinkable monomer is preferably 1 to 200 parts by weight, more preferably 5 to 100 parts by weight.

Hydrophilic crosslinkable monomer is 1 per 100 parts by weight of polymer.
~ 200 parts by weight. If it is less than 1 part by weight, sufficient hydrophilicity and crosslinkability will not be imparted, and conversely, if it exceeds 200 parts by weight, the water resistance of the film will be reduced and the crosslinking density will be too high.
The content of the hydrophilic crosslinkable monomer is preferably 1 to 100 parts by weight.

Surfactant is not more than 200 parts by weight per 100 parts by weight of polymer. If it exceeds 200 parts by weight, the amount of the surfactant exuded becomes too much. The preferred content is 1 to 100 parts by weight.

When forming a hydrophilic film, a composition is formed by using a suitable combination of the above components without adding a solvent to form a coating solution. When the hydrophilic film is 30 μm or less,
A solvent-containing coating solution can also give a good surface condition, but if it is thicker than that, the surface condition deteriorates sharply.

A hydrophilic film can be formed on a supporting film by the following method using the above composition.

First, a composition containing no solvent is adjusted to an appropriate viscosity by a method such as heating, and then applied on a support film by a roll coating method such as a gravure reverse method, a triple reverse method, a gravure direct method, a four reverse method. To do.

After the composition is applied to the support film, for example, when the surface is to be mirror-finished, a mirror-like film is laminated on the film and irradiated with an electron beam.

As an irradiation method, an arbitrary method such as an electron curtain method or a beam scanning method can be used.
The irradiation of the electron beam allows the polymer to be crosslinked regardless of the presence or absence of a functional group, and the hydrophilic monomer and the hydrophilic crosslinkable monomer are crosslinked to the polymer in the form of graft polymerization or block polymerization. This point is a significant difference from the crosslinking by ultraviolet irradiation. The energy of the irradiation electron beam is 150 to 200
The dose is about keV, and the dose varies depending on the composition of the composition and the desired degree of crosslinking density. The more the polymer has a functional group, the smaller the irradiation dose, and the higher the crosslink density, the higher the irradiation dose. In particular, when a surfactant is contained, if the crosslinking density is too high, the exudation thereof becomes insufficient and the antifogging (condensation preventing) action is lowered, so that the control of the irradiation dose is important.

From the above, the irradiation dose is generally 0.5 to 20 Mrad,
If it is less than 0.5 Mrad, unreacted monomer may remain, and if it exceeds 20 Mrad, the crosslinking density becomes too high.

After forming the hydrophilic film by electron beam irradiation, if a mirror surface film or the like is attached to the surface, it is peeled off. Further, the surface film can be used as a protective film without being peeled off until the time of construction.

By thus forming the hydrophilic film using the non-solvent type coating liquid, the surface condition can be improved even if the hydrophilic film is thicker than 30 μm. Further, by irradiating an electron beam with the film stuck on the surface, the surface can be made into a desired state such as a mirror surface.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited thereto.

Example 1 Using a separable flask (2) equipped with a heating and stirring device and a separable cover, isophorone diisocyanate 44
4 g was placed in a flask, 0.2 g of dinormal butyltin dilaurate as a catalyst was added dropwise, and the mixture was heated with stirring at 40 ° C. Butylene adipate (“Nipporan N-4570”, manufactured by Nippon Polyurethane Industry Co., Ltd.) (650 g) was gradually added so that the temperature in the system did not show a sudden increase, and the reaction was allowed to proceed. After 2 hours, 232 g of 2-hydroxyethyl acrylate was added dropwise to adjust the reaction temperature.
The temperature was raised to 60 ° C., and stirring was continued until the peak due to the isocyanate group at 2330 cm ^{−1 in} the IR spectrum disappeared. In this way, urethane acrylate (I) was produced in a yield of almost 100%.

To 100 parts by weight of the obtained urethane acrylate (I),
100 parts by weight of 2-hydroxyethyl methacrylate as a hydrophilic monomer, 10 parts by weight of neopentyl glycol diacrylate (NPGDA) as a cross-linking agent, and 5 parts by weight of Emulgen 106 (manufactured by Kao Corporation) as a surfactant are uniformly mixed. A coating liquid was prepared. This was applied to a 50 μm thick easily-adhesive-treated polyester film (HP-7 manufactured by Teijin Ltd.) by a roll coating method in a thickness of 50 μm,
25 μm polyester film (Lumirror T type) is laminated, and electron curtain type electron beam irradiation device (ESI
The coating film was cured by irradiating an electron beam of 175 keV with 5 Mrad.

The antifogging property of the obtained antifogging sheet was evaluated by the following test.

(1) Exhalation test (check whether or not clouding occurs due to exhalation) Test evaluation ○: No fog x: Cloudy occurs (2) 50 ℃ steam test (fog occurs by applying film to hot water at 50 ℃) Test evaluation ◎: No fog for 1 hour or more ○: No fog for 3 minutes or more △: Fogging occurs for less than 3 minutes ×: Immediate fogging occurs for the antifogging sheet obtained by the method according to this example. The antifogging property was ◯ in (1) and ⊚ in (2).

Example 2 In the same manner as in Example 1 except that 1000 g of carbonate diol (“Placcel CD-210”, manufactured by Daicel Chemical Industries, Ltd.) was used instead of the butylene adipate used in Example 1, urethane acrylate (II ) Was synthesized.

100 parts by weight of the obtained urethane acrylate (II), 100 parts by weight of glycerol monomethacrylate (GM) as a hydrophilic monomer, and Resist SA-1 as a surfactant.
30 parts by weight of Daiichi Kogyo Yakuhin Co., Ltd. were mixed uniformly,
Then, the coating was performed in the same manner as in Example 1 to obtain an electron beam cured film having a thickness of 40 μm.

The antifogging property of the obtained antifogging sheet is (1) ○, (2) ◎
Met.

Example 3 100 parts by weight of acrylic polymer, G as a hydrophilic monomer
M 200 parts by weight, pentaerythritol acrylate (PETA) 20 parts by weight as a cross-linking agent, and Exel O as a surfactant
A coating liquid consisting of 5 parts by weight of -95R (manufactured by Kao Corporation) was prepared.

The coating solution was prepared by the following procedure. That is,
70 parts by weight of methyl methacrylate, 39 parts by weight of 2-hydroxyethyl methacrylate, 0.15 parts by weight of azobisisobutyronitrile, and 70 parts by weight of methyl ethyl ketone are equipped with a reflux tube and a stirrer, and a nitrogen replaceable separable flask is provided. , And the mixture was reacted in an N ₂ stream at 85 ° C. for 5 hours. Thereafter, 0.15 part by weight of azobisisobutyronitrile was further added, and the reaction was carried out for 3 hours. After reaction, GM218 parts by weight, PETA21.8
By weight, O-95R (5.45 parts by weight) was added, and methyl ethyl ketone was removed with heating and stirring to obtain the desired coating liquid.

A polyethylene terephthalate film having a thickness of 50 μm and easily adhered by a roll coating method (Teijin Co., Ltd.)
It was coated on HP-7) and dried at 100 ° C., and then electron beam irradiation was performed in the same manner as in Example 1 to cure the coating film with a thickness of 50 μm.

The antifogging property of the obtained antifogging sheet is (1) ○, (2) ◎
Met.

Examples 4 to 8 Using the compositions having the respective compositions shown in Table 1, an antifogging sheet was prepared in the same manner as in Example 1 and the same test was conducted. The results are also shown in Table 1.

Comparative Example 1 A composition having a composition shown in Table 1 was applied to a thickness of 3 μm, and the antifogging property was evaluated. As a result, (1) was ◯ and (2) was Δ.
And the anti-fogging performance deteriorated.

Comparative Example 2 The composition of Example 6 was used to apply a thickness of 5 μm,
As a result of long-term evaluation of steam temperature at 50 ° C. in (2), performance was deteriorated (fogging occurred) in about 50 hours at 5 μm thickness. On the other hand, with the film thickness of Example 6, no haze occurred even after 100 hours had passed.

〔The invention's effect〕

As described above, in the antifogging sheet of the present invention, by increasing the film thickness of the hydrophilic film, the absolute amount of water taken into the film can be increased and the antifogging performance can be improved. In addition, even when a surfactant as a long-term antifogging agent is added, the thick film has a larger absolute amount of the surfactant than the thin film. When the thin film is the same, the thick film can maintain the antifogging property for a longer period of time.

Claims (6)

(57) [Claims] 1. A hydrophilic film containing a polymer, a hydrophilic monomer and a surfactant, which is crosslinked by electron beam irradiation and has a thickness of more than 30 μm is formed on the surface of a support film. Anti-fog sheet. 2. The antifogging sheet according to claim 1, wherein
An antifogging sheet, wherein the hydrophilic film comprises a polymer, a hydrophilic monomer, a crosslinkable monomer and a surfactant, and is crosslinked by electron beam irradiation. 3. A hydrophilic film containing a polymer, a hydrophilic crosslinkable monomer and a surfactant and crosslinked by electron beam irradiation and having a thickness of more than 30 μm is formed on the surface of the support film. Anti-fog sheet to be used. 4. The antifogging sheet according to claim 1, wherein the hydrophilic film contains 100 parts by weight or less of a surfactant per 100 parts by weight of the polymer. Anti-fog sheet to be used. 5. A non-solvent type coating liquid containing a polymer, a hydrophilic monomer and a surfactant is prepared, and the coating liquid is coated on a support film so that the thickness after cross-linking exceeds 30 μm. A method for producing an anti-fogging sheet, which comprises crosslinking by irradiation with rays. 6. The method according to claim 5, wherein after the application of the coating solution, electron beam irradiation is carried out in the state where the film is stuck on the surface, and then the film is peeled off.