JP2545241B2 - Method for improving antifogging property of hydrophilic film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to articles such as automobile windows, side mirrors, household mirrors, bath windows and mirrors, sunglasses, spectacle lenses, watch cover glasses, ski goggles and the like. The present invention relates to a method for improving the antifogging property of a hydrophilic film that is attached to provide the surface of the product with antifogging property.

[Prior Art] Conventionally, as a method for imparting antifogging property to the surface of a product which is often exposed to moisture like the above-mentioned article, (a) a method of directly applying an antifogging paint, and (b) a hydrophilic surface of the film. Chemically treated or laminated with a hydrophilic film, and (c) laminated with a surfactant-kneaded film are used.

[Problems to be Solved by the Invention] However, in the above method (a), the antifogging paint is only attached to the surface of the base material, and it easily flows out in a high-humidity atmosphere and has a long duration. There's a problem. In the method (b), the initial antifogging property is excellent, but the durability is problematic.
Although the method (c) has improved durability as compared with the methods (a) and (b), sufficient durability cannot be expected due to leaching of the surfactant.

Furthermore, if the anti-fog layer is left in the air for a long time,
Dust and the like in the atmosphere may adhere, and as a result, the antifogging performance may deteriorate.

In view of the above problems, an object of the present invention is to provide a method for maintaining the antifogging property of a hydrophilic film for a long time.

[Means for Solving the Problems] As a result of various studies to solve the above problems, a hydrophilic film cross-linked by electron beam irradiation is coated with a solution containing a surfactant to give a hydrophilic film. It was discovered that the surfactant can be introduced into the film at the same time as the surface of, and the antifogging property is maintained for a long time, and the present invention was conceived.

In the present invention, the hydrophilic film basically crosslinks the hydrophilic monomer and the like to the polymer by irradiation with an electron beam,
If necessary, it contains a surfactant. Specific combinations are (a) polymer + hydrophilic monomer, (b) polymer + hydrophilic monomer + surfactant, (c) polymer + hydrophilic monomer + crosslinkable monomer, (d) polymer + hydrophilic monomer. + Crosslinkable monomer + surfactant, (e) polymer + hydrophilic crosslinkable monomer, (f) polymer + hydrophilic crosslinkable monomer + surfactant, (g) polymer + hydrophilic monomer + hydrophilic crosslinkable monomer, And (h) polymer + hydrophilic monomer + hydrophilic crosslinkable monomer + surfactant. In all combinations of the above, the polymer may be either a functional polymer or a non-functional polymer.

As will be described later, the surfactant does not need to be sufficiently added to the hydrophilic film from the beginning, and may be any amount as long as it becomes a sufficient amount after the solution containing the surfactant is applied. In addition, the present invention can be applied to the case where the hydrophilic film initially contains a sufficient amount of the surfactant and the surfactant disappears due to long-term use. It should be understood that the combination of the above (b), (d), (f) and (h) is such.

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

In order to improve the compatibility with the hydrophilic monomer, a hydrophilic group may be previously introduced into the non-functional polymer. For this, it is preferable to use a copolymer of a monomer having a hydrophilic group (hydrophilic monomer) described below and a hydrophobic monomer. The ratio of hydrophilic monomer to non-functional polymer is 50
It is at most mol%, and if it exceeds this range, 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.

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 base, and a phosphoric acid group. For example, 2-hydroxyethyl acrylate, methacrylic acid 2-hydroxyethyl, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylic acid, methacrylic acid, metal acrylate, metal methacrylate, acrylamide, methacrylamide, dimethylaminopropyl acrylamide, dimethylaminopropyl methacrylamide , N-acryloylmorpholine, N-methacryloylmorpholine, N-methylolacrylamide, N-methylolmethacrylamide, t
-Butylacrylamide, t-butylmethacrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide, Nn-butoxyacrylamide, N, N-dimethylacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethyl Aminopropyl methacrylamide, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, glycerol monomethacrylate, 2-acrylamide 2-methylpropanesulfonic acid, methacrylamidopropyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, mono (2-methacryloxy) Ethyl) 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.

Examples of such hydrophilic crosslinkable monomers include 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, 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 and other diol / diglycidyl ether 1: 2 adducts with acrylic acid, penta Risuri Tall 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,
Pentaerythritol derivatives such as dipentaerythritol penta (meth) 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, acrylamide / methylol urea, acrylamide derivatives such as N, N-diallyl acrylamide, etc.

The hydrophilic film used in the present invention may also contain a surfactant. The surfactant has an effect of imparting anti-fogging properties by gradually oozing out 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.

When the crosslinking monomer is added, it is 1 to 300 parts by weight per 100 parts by weight of the polymer. If the amount is less than 1 part by weight, the unreacted hydrophilic monomer is insufficiently crosslinked, and if it exceeds 300 parts by weight, the crosslink density of the whole film 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.

A surfactant is not required, but when added, does not exceed 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 the surfactant almost disappears, the antifogging property can be restored by the method of the present invention as described later.

When forming a hydrophilic film, a solvent may be appropriately contained in a composition comprising an appropriate combination of the above components.

Solvents that can be used include methanol, ethanol,
Alcohols such as isopropanol, methyl cellosolve and ethyl cellosolve, ethers such as tetrahydrofuran, ketones such as methyl ethyl ketone, acetone and methyl isobutyl ketone, esters such as ethyl acetate and butyl acetate, aromatic carbonization such as toluene and xylene Hydrogen, etc.
Alternatively, there is a mixed solvent of these.

The amount of the solvent added varies depending on the film forming method, but when forming a coating film by coating, the solid content in the composition is 5 to 50% by weight, preferably 5 to 30% by weight. Generally, the amount of the solvent added is 6000 parts by weight or less per 100 parts by weight of the polymer.

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

First, the composition adjusted to an appropriate viscosity is applied by a roll coating method such as a gravure reverse method, a three-reverse method, a gravure direct method, or a four-reverse method. Depending on the application, it is preferable to apply the composition on a support such as a base film. Although transparent plastic is generally used as the base film, a colored film or an opaque film may be used for the purpose of decoration or the like. In addition, a film that has been subjected to an easy-adhesion treatment may be used in order to improve the adhesiveness with the coating film. As the material of the base film, polyester, polyethylene, polypropylene, polycarbonate, polyacrylate, polystyrene, polyamide, polyimide, polyvinyl chloride, and the like can be used.

The coating film of the composition formed on the base film or the like is dried while heating with a dryer or the like in order to remove the solvent by evaporation. If the heating temperature is too high, the monomers will also evaporate.

Next, the coating film is irradiated with an electronic film. As an irradiation method, an arbitrary method such as an electron curtain method or a beam scanning method can be used. Irradiation with an 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 electron beam used for irradiation is about 150 to 200 keV, and the amount of irradiation depends 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. Particularly when a surfactant is contained, if the crosslink density is too high, the exudation thereof will be insufficient and the antifogging effect will be reduced, so control of the irradiation dose is important. From the above, the irradiation dose is generally 0.5 to 200 Mrad, and if it is less than 0.5 Mrad, unreacted monomer may remain, and if it exceeds 200 Mrad, the crosslinking density becomes too high.

The hydrophilic film thus prepared has a structure in which the hydrophilic skeleton and / or the hydrophilic crosslinkable monomer are crosslinked in the polymer skeleton, and the entire film is crosslinked, so that sufficient hardness and strength are obtained. Have.

Since the hydrophilic film used in the present invention can be formed as a coating film on the base film, it can be attached to a desired place such as a mirror or a window by applying an adhesive to the base film. Further, since it can be made flexible, it can be attached to curved surfaces such as glasses and goggles.

Even if the hydrophilic film used in the present invention initially contains a surfactant, it is used for applications that are exposed to water vapor for a long period of time. It oozes out to the surface, and finally the surfactant almost disappears, and the antifogging property is lost for a long time.

Further, when no surfactant is contained, there is a problem in that although the initial antifogging property is good, the long-term antifogging property is poor.

In these cases, the method according to the present invention allows the surfactant to be incorporated into the film to exhibit a long-term antifogging property.

Next, as the surfactant applied to the hydrophilic film in the present invention, the same surfactant as that added to the hydrophilic film can be used alone or in combination. Solvents for dissolving surfactants include alcohol, water, ketone, ether,
Polar solvents such as amides and mixtures thereof can be used. As alcohol, methanol, ethanol,
Examples include propanol and ptanol. From the viewpoint of production, alcohol, water, and a mixed solution of alcohol and water are preferable. The ratio of these solvents to the surfactant is 0.1 to 50 parts by weight of the surfactant per 100 parts by weight of the solvent. If it is less than 0.1 part by weight, the performance is difficult to be exhibited, and if it exceeds 50 parts by weight, the amount of the surfactant is too large and it becomes difficult to apply it.

Next, the method of applying a solution containing a surfactant to the hydrophilic film is a gravure reverse method, a gravure direct method,
Examples thereof include a roll coating method such as the three-reverse method, a spray method, and a method in which a solution containing a surfactant is preliminarily contained in cloth, paper or the like and applied. In this way, it was found that the hydrophilic film was appropriately swollen by a polar solvent such as water or alcohol, and thereby the surfactant entered and was taken into the inside of the film simultaneously with the surface of the film. This is an important feature of the present invention. That is, since the surfactant can be incorporated into the inside of the film due to the swelling effect of the hydrophilic film with a polar solvent such as water or alcohol, long-term antifogging property can be imparted. Further, the hydrophilic film used in the present invention has sufficient mechanical strength because it is crosslinked by irradiation with an electron beam, and is not easily scratched. Therefore, it is suitable for the method according to the present invention, and this method can be repeated, and the antifogging property can be maintained semipermanently.

According to the present invention, it is possible to apply a solution containing a surfactant to a hydrophilic film so that the solution is attached to the surface of the hydrophilic film, and at the same time, the surfactant can be introduced into the inside of the film by a swelling action. Furthermore, the surface of the hydrophilic film can be cleaned. Furthermore, after long-term use, if the coating is applied when the antifogging property of the hydrophilic film is lowered, the antifogging property can be easily restored, and in this way the antifogging property can be maintained semipermanently. it can.

[Examples] The present invention will be described more specifically with reference to the following examples.

Example 1 300 parts by weight of an acrylic polymer solution, 70 parts by weight of 2-hydroxyethyl methacrylate as a hydrophilic monomer, 10 parts by weight of pentaerythritol triacrylate as a hydrophilic crosslinkable monomer, and 300 parts by weight of methyl ethyl ketone as a solvent were uniformly added. By mixing, the composition of the hydrophilic film used in the present invention was prepared.

The acrylic polymer was prepared by the following procedure. That is, 700 parts by weight of methyl methacrylate, 2
-Hydroxyethyl methacrylate 390 parts by weight, azobisisobutyronitrile 1.5 parts by weight and methyl ethyl ketone 2210 parts by weight, a reflux tube and a stirrer equipped, put into a nitrogen-substituted separable flask, 85 in N ₂ stream. 5 at ℃
Allowed to react for hours. Thereafter, 1.5 parts by weight of azobisisobutyronitrile was further added and the reaction was carried out for 3 hours. The resulting acrylic polymer solution had a concentration of 33% by weight and was measured by gel permeation chromatography (GPC),
The weight average molecular weight (w) was 7.5 × 10 ⁴ . No peak of the monomer was observed.

A roll coater uniformly coats the above composition on a 50 μm thick polyester film (Lumirror T type) with a thickness of 5 μm, and after drying with a dryer, an electron curtain type EB device (manufactured by ESI) is used to apply an electron beam of 175 keV to 5 Mr
Irradiation was carried out to cure the coating.

Polyoxyethylene lauryl ether (trade name "Emulgen 106", manufactured by Kao Corporation) was used as a surfactant on the hydrophilic film obtained by the above method using a roll coater.
% Water and alcohol 1: 1 solution was applied and dried with a drier.

The following test performed evaluation of the antifogging property of the obtained hydrophilic film.

(1) Exhalation test (Check if the film is exposed to steam to cause fogging.) Test evaluation: No fog, x occurs. (2) 50 ° C steam test (use film in 50 ° C steam) It is checked whether or not fogging occurs.) Test evaluation ○: Not fogged for 50 hours Δ: Fogging within 1 hour ×: Immediate fogging Anti-fogging property of the film obtained by the method of the present invention is
Both of (1) the breath test and (2) the 50 ° C steam test were evaluated as ◯.

Examples 2 to 10 A hydrophilic film was prepared in the same manner as in Example 1 using each composition shown in Table 1, sprayed with a solution containing the surfactant shown in Table 1 and dried. , Did the same test. The results are also shown in Table 1.

The urethane acrylate of Example 4 was prepared by the following procedure. That is, the same apparatus as in Example 1 was used, in which butylene adipate (“Nipporan N-45
70 "650 g of Nippon Polyurethane Co., Ltd., 300 g of methyl ethyl ketone, and 444 g of isophorone diisocyanate were put, and a solution obtained by dissolving 1 g of dibutyltin dilaurate in 10 g of methyl ethyl ketone was added dropwise with stirring at 60 ° C. 5
2-Hydroxyethyl acrylate (232 g) was added dropwise with stirring in a nitrogen stream, and after completion of the addition, stirring was continued at 70 ° C. for 3 hours. -NCO by infrared absorption spectrum
After confirming that the peak of the group disappeared, the reaction was terminated.
The weight average molecular weight (w) of the obtained polymer was GP.
It was 1700 by C.

Examples 11 to 15 After newly adding the surfactants shown in Table 2 to the compositions of the hydrophilic membranes of Examples 1 and 3 and 4, 3 and 6 and 9 shown in Table 1, respectively, A hydrophilic film containing a surfactant was obtained in the same manner as in. When these hydrophilic membranes were immersed in water for 10 days, dried and subjected to the same 50 ° C. steam test as in Example 1, it was confirmed to be Δ.

Next, a solution containing a surfactant shown in Table 2 was sprayed and dried, and then the same test as in Example 1 was performed. The results are also shown in Table 2.

Further, these hydrophilic membranes were again immersed in water for 10 days, and the solution containing the surfactant shown in Table 2 was applied again.
Both the exhalation test and the 50 ° C steam test were good.

Comparative Example 1 Instead of the hydrophilic film used in the present invention, a PET film and glass were sprayed with the solution containing the surfactant used in Examples 2 to 4 and then dried, and the same test as in Example 1 was performed. Although the exhalation test was good, the 50 ° C steam test was bad, and the long-term anti-fog property was poor. From this, it can be seen that the long-term anti-fog property is not imparted even if the solution containing the surfactant is applied to a material other than the hydrophilic film.

[Effects of the Invention] As described above, according to the present invention, by applying a solution containing a surfactant to a hydrophilic film, the film is swollen simultaneously with the surface of the hydrophilic film. A surfactant is introduced in the interior, and as a result, the antifogging property can be maintained. Further, the function of cleaning the surface of the hydrophilic film can be performed at the same time. Further, since the hydrophilic film used in the present invention has mechanical strength, it can be wiped off, and even if the antifogging property is lowered after long-term use, it is semipermanently antifogging property by repeating this method. Can be sustained.

Claims (5)

(57) [Claims] 1. An antifogging property of a hydrophilic film, characterized in that a hydrophilic film containing a polymer and a hydrophilic monomer and crosslinked by electron beam irradiation is applied with a solution containing a surfactant. How to improve. 2. The method according to claim 1, wherein the hydrophilic film is formed by crosslinking a mixture of a polymer, a hydrophilic monomer and a crosslinkable monomer by electron beam irradiation. Method. 3. The method according to claim 1, wherein the hydrophilic film is obtained by crosslinking a mixture of a polymer and a hydrophilic crosslinkable monomer by electron beam irradiation. 4. The method according to any one of claims 1 to 3, wherein the hydrophilic film contains 100 parts by weight or less of a surfactant per 100 parts by weight of the polymer. From the above-mentioned surfactant is used. 5. The method according to any one of claims 1 to 4, wherein the solution of the surfactant is water.
A method comprising containing alcohol or a mixed solvent of water and alcohol.