WO2013031738A1

WO2013031738A1 - Antifogging film and antifogging film-coated article

Info

Publication number: WO2013031738A1
Application number: PCT/JP2012/071615
Authority: WO
Inventors: 大家　和晃; 神谷　和孝; 寺西　豊幸; 周平村田
Original assignee: 日本板硝子株式会社
Priority date: 2011-08-29
Filing date: 2012-08-27
Publication date: 2013-03-07

Abstract

The present invention provides: an antifogging film capable of maintaining excellent antifogging properties over a long period of time, the antifogging film having film hardness and abrasion resistance sufficient for use in construction and vehicles or in an antifogging mirror while maintaining adequate antifogging properties; and an antifogging film-coated article having the antifogging film. The present invention is an antifogging film comprising: a moisture-absorbing composite film containing polyvinyl acetal resin, a hydrolysate or partial hydrolysate of silicon alkoxide, and colloidal silica; and a hydrophilic polymer brush secured on the moisture-absorbing composite film. The present invention is also an antifogging film-coated article having the antifogging film.

Description

Antifogging film and antifogging film coated article

The present invention relates to an antifogging film and an antifogging film-coated article, and more particularly to an antifogging film formed on a hard substrate and an antifogging film-coated article having the antifogging film.

The antifogging film coated article in which an antifogging film is provided on a hard substrate is, for example, an antifogging mirror for bathrooms, toilets, etc., an antifogging window glass or antifogging mirror for automobiles, etc. It is used for various applications such as window glass.

By the way, as an antifogging film composed of a single layer film using a water-absorbing polymer compound, a coating type antifogging agent is disclosed in Patent Document 1 after applying only a polyvinyl acetal resin and then drying at room temperature to form an antifogging film. It is disclosed. In Patent Document 2, an antifogging layer made of a polyvinyl acetal resin having an acetalization degree of 2 to 40 mol% is provided on the surface of an article such as glass, a mirror, or a plastic film, or a water-soluble resin layer is provided on the article surface. Further, an antifogging article is disclosed in which an antifogging layer comprising a polyvinyl acetal resin having an acetalization degree of 2 to 40 mol% is provided thereon.

On the other hand, as a water-absorbing composite film in which a polyvinyl acetal resin and an inorganic component are mixed, for example, in Patent Document 3 and Patent Document 4, a hydrolyzate of a polyvinyl acetal resin having a degree of acetalization of 10 mol% or less and an alkylsilyl isocyanate or An anti-fogging base material is disclosed in which a water-absorbing composite film in which a partial hydrolyzate is mixed, and a water-permeable protective film and water-repellent layer having a water permeability of 3 to 10 nm are laminated thereon.

Further, as an anti-fogging film in which a surfactant is dispersed in a film made of a water-absorbing resin, for example, in Patent Document 5 and Patent Document 6, a urethane resin in which a surfactant and trialkanolamine are fixed is formed. Agents and antifogging membranes are disclosed.

JP-A-6-157794 Japanese Patent Laid-Open No. 6-158031 JP 2001-146585 A JP 2001-152137 A JP 60-85939 A JP 2004-269851 A

However, in the techniques described in Patent Document 1 and Patent Document 2, the abrasion resistance, abrasion resistance, and wet cloth abrasion resistance are low even in a dry state, and the performance is further deteriorated at the time of moisture absorption. In particular, there is a problem that it cannot be used in an environment where the coating surface is wiped. This is due to the following reasons.
That is, these are monolayer films using a water-absorbing polymer compound, and are in a state where the water-absorbing polymer resin is exposed to the surface. This is because when the addition of a curing agent or the like is poor, the film strength increases, but the water absorption decreases and sufficient antifogging performance cannot be exhibited.

In the techniques described in Patent Document 3 and Patent Document 4, the water-absorbing composite film single layer cannot obtain high film hardness and wear resistance while maintaining sufficient anti-fogging properties. A protective layer is required on the upper layer of the film. This is because in water-absorbing composite film monolayers, increasing the amount of alkylsilyl isocyanate added increases the proportion of the inorganic component (SiO ₂ ) in the skeleton of the coating, thus improving scratch resistance and wear resistance. However, since the swelling and flexibility are lowered, the water absorption is lowered, the sufficient antifogging property cannot be maintained, the alkylsilyl isocyanate can be added only in a small amount, and the sufficient film hardness This is because no longer can be obtained. In addition, in order to increase the hardness and abrasion resistance of the entire film, a protective film having a water permeability and a water repellent layer are laminated as a protective layer, but it is necessary to increase the film thickness. As a result, the anti-fogging property is lost and the anti-fogging property, film hardness, and abrasion resistance cannot be combined in total.

Furthermore, in the technique described in Patent Document 5, it does not have film hardness or wear resistance that can be used for architectural or vehicle window glass or mirrors, and the surfactant is supported in the film. However, the surface active agent flows out by wiping the poultice or repeatedly forming a water film on the surface, and the hydrophilicity is lowered in a short time.
Even in the technique described in Patent Document 6, although the wear resistance is improved as compared with the prior art, it cannot be said that it is sufficient for architectural use or vehicle use. Similarly, since the surfactant flows out, it is difficult to maintain excellent antifogging performance.

The present invention has been made under such circumstances, and has film hardness and abrasion resistance that can be used for construction, vehicles, or antifogging mirrors while maintaining sufficient antifogging properties. The object of the present invention is to provide an antifogging film capable of maintaining excellent antifogging properties over a long period of time and an antifogging film-coated article having the antifogging film.

As a result of intensive studies to achieve the above object, the present inventors have obtained the following knowledge.
First, a water-absorbing composite film containing polyvinyl acetal resin, hydrolyzate or partial hydrolyzate of silicon alkoxide, and colloidal silica can have sufficient film hardness and wear resistance that can be used for construction and vehicles. I found out that I can do it. However, when the film has sufficient film hardness and wear resistance, the water absorption amount of the film decreases, and after the water absorption is saturated, the surface of the film becomes cloudy. On the other hand, it has been found that by imparting hydrophilicity to the surface of the coating, after water absorption is saturated, a water film is formed on the surface of the coating, so that no clouding occurs.
Here, as a method for imparting hydrophilicity, in the case where a surfactant is dispersed in the coating, the surfactant flows out by wiping the coating surface with a compress or by repeatedly forming a water film on the coating surface. As a result, the hydrophilicity of the coating surface is reduced in a short period of time.
In order to maintain the hydrophilicity of the coating surface over a long period of time, it is necessary to chemically bond a hydrophilic material to the coating surface and inside, and to absorb the polymer brush having a crosslinking group and many hydrophilic groups in the structure. The present inventors have found that wet cloth wear resistance and repeated anti-fogging properties can be greatly improved by high-density crosslinking on a porous composite film.
The present invention has been completed based on such findings.

That is, the present invention is as follows.
[1] A water-absorbing composite film containing a polyvinyl acetal resin, a hydrolyzate or partial hydrolyzate of silicon alkoxide, and colloidal silica, and a hydrophilic polymer brush fixed on the water-absorbing composite film. Anti-fogging film.
[2] The antifogging film according to [1], including a primer layer between the water-absorbing composite film and the hydrophilic polymer brush.
[3] The antifogging film according to [2], wherein the primer layer contains a hydrolyzate or partial hydrolyzate of ethyl silicate.
[4] The antifogging film according to [2], wherein the primer layer contains a hydrolyzate or partial hydrolyzate of silicon alkoxide.
[5] The antifogging film according to [3] or [4], wherein the primer layer further contains colloidal silica.
[6] The water-absorbing composite film has 30 to 80 parts by mass of colloidal silica and 5 to 55 parts by mass of silica equivalent particles derived from a hydrolyzate or partial hydrolyzate of silicon alkoxide with respect to 100 parts by mass of the polyvinyl acetal resin. The antifogging film according to any one of [1] to [5], which is contained in a proportion of parts.
[7] An antifogging film-coated article having a hard substrate and the antifogging film according to any one of [1] to [6] formed on the hard substrate.
[8] The antifogging film-coated article according to [7], wherein the hard substrate is a mirror or a translucent hard substrate.

According to the present invention, while maintaining sufficient antifogging properties, it has film hardness and abrasion resistance that can be used for construction, vehicles, or antifogging mirrors, and has excellent antifoaming properties over a long period of time. It is possible to provide an antifogging film capable of maintaining the fogging property and an antifogging film-coated article having the antifogging film.

[1] Antifogging film The antifogging film of the present invention comprises a water-absorbing composite film and a hydrophilic polymer brush fixed on the water-absorbing composite film. Hereinafter, each film will be described in detail.

(1) Water-absorbing composite film The water-absorbing composite film contains a polyvinyl acetal resin, a hydrolyzate or partial hydrolyzate of silicon alkoxide, and colloidal silica.

(Polyvinyl acetal resin)
The polyvinyl acetal resin used in the present invention can be obtained by subjecting polyvinyl alcohol to an acetalization reaction by condensing aldehyde with polyvinyl alcohol. The degree of acetalization is usually set to 2 to 40 mol%, preferably 3 to 30%. It is set to mol%, more preferably 5 to 20 mol%. The degree of acetalization can be measured based on, for example, ¹³ C nuclear magnetic resonance spectroscopy.
If the degree of acetalization is in the range of 2 to 40 mol%, a water-absorbing composite film having good water absorption and water resistance and sufficiently exhibiting antifogging properties can be formed. For acetalization of polyvinyl alcohol, a known method such as a precipitation method using an aqueous medium in the presence of an acid catalyst or a dissolution method using a solvent such as alcohol can be employed. A polyvinyl acetal resin can also be obtained by using a polyvinyl acetate resin as a raw material and performing saponification and acetalization in parallel.

As the polyvinyl alcohol, those having an average degree of polymerization of 200 to 4500, preferably 500 to 4500 are generally used. When the average degree of polymerization is 200 or more, it is possible to synthesize polyvinyl alcohol, and when the average degree of polymerization is 4500 or less, the solution viscosity does not become excessively high, and it is practically used as an antifogging film-coated article. From the viewpoint of sex. The higher the average degree of polymerization, the better the water resistance and water absorption.
The saponification degree of polyvinyl alcohol is generally 75 to 99.8 mol%. If the degree of saponification is 75 mol% or more, the solubility during the reaction is sufficient, and if it is 99.8 mol% or less, synthesis of polyvinyl alcohol becomes possible. The lower the saponification degree, the better the water absorption.

Examples of the aldehyde to be subjected to condensation reaction with polyvinyl alcohol include aliphatic aldehydes such as formaldehyde, acetaldehyde, butyraldehyde, hexyl carbaldehyde, octyl carbaldehyde, decyl carbaldehyde; benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde , Other aromatic aldehydes such as alkyl-substituted benzaldehyde, chlorbenzaldehyde, and other halogen-substituted benzaldehydes; aromatic aldehydes having a substituent such as hydroxy group, alkoxy group, amino group, cyano group on the aromatic ring; naphthaldehyde And aldehydes having a condensed aromatic ring such as anthraldehyde.
In particular, an aromatic aldehyde is preferable in that a resin having good water absorption, water resistance, and transparency can be obtained. Aromatic aldehydes have strong hydrophobicity and are excellent in water resistance even at a low degree of acetalization. Therefore, many hydroxyl groups remain and water absorption is excellent.

The content of the polyvinyl acetal resin in the water-absorbing composite film is usually 40 to 70% by mass, preferably 40 to 60% by mass, and more preferably 40 to 50% by mass from the viewpoints of film hardness, water absorption and antifogging properties. %.

(Silicon alkoxide)
The water-absorbing composite film contains a hydrolyzate or partial hydrolyzate of silicon alkoxide as an essential component.
Silicon alkoxides include tetra acids that can be easily hydrolyzed with inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and organic acids such as p-toluenesulfonic acid, methanesulfonic acid, trichloroacetic acid, and trifluoroacetic acid to form silica. Alkoxysilane is preferably used. The four alkoxy groups of this tetraalkoxysilane may be the same or different, but from the viewpoint of availability, the same one is usually used. In addition, the alkoxy group is preferably a lower alkoxy group having 1 to 4 carbon atoms from the viewpoint of hydrolyzability.
Such tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetraisobutoxysilane, tetra-sec-butoxysilane, tetra- Examples thereof include tert-butoxysilane. One of these tetraalkoxysilanes may be used alone, or two or more thereof may be used in combination.

In the present invention, 1 mol of SiO ₂ is formed from 1 mol of silicon alkoxide, and the silica equivalent particle amount derived from the hydrolyzate or partial hydrolyzate of silicon alkoxide is calculated from the amount of silicon alkoxide used. The water-absorbing composite film preferably contains the silica-converted particles in an amount of 5 to 55 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin. When the content of the silica-converted particles is 5 parts by mass or more, the water-absorbing composite film has good antifogging properties and high pencil hardness. On the other hand, when the content is 55 parts by mass or less, silking does not occur on the surface of the composite film, and a smooth coating surface is obtained. From the above viewpoint, the preferable content is in the range of 20 to 55 parts by mass, more preferably 30 to 55 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin.

(Colloidal silica)
Colloidal silica contained in the water-absorbing composite film is SiO ₂ fine particles having an average particle diameter of about 5 to 50 nm. By containing this colloidal silica, the water-absorbing composite film has a certain degree of strength and flexibility. In addition, the proportion of the inorganic component in the composite film can be increased, and the addition of this colloidal silica forms fine voids in the film, which makes it easier to incorporate moisture into the film. Therefore, the hardness of the coating can be improved while maintaining sufficient antifogging properties.
In addition, since the proportion of the inorganic component in the film can be increased by adding colloidal silica, an antifogging film having sufficient film hardness and sufficient antifogging properties that does not cause scratches on the film even when the pencil hardness is 4H or higher. This eliminates the need for a protective layer on the upper layer.
If the average particle size of the colloidal silica is too large, the haze value of the film becomes high and the film may become cloudy. If it is too small, aggregation tends to occur and the film cannot be uniformly dispersed. Therefore, the average particle size of colloidal silica is preferably in the range of 5 to 50 nm, more preferably in the range of 8 to 20 nm.
The average particle size of the colloidal silica can be measured by a laser diffraction light scattering method or the like.

The content of colloidal silica in the water-absorbing composite film is 30 to 80 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin described above. When the colloidal silica content is 30 parts by mass or more, the pencil hardness of the composite film can be 4H or more, and when it is 80 parts by mass or less, the hardness of the water-absorbing composite film is improved. In addition, in the pre-baking process described later, the water absorption is not lowered and the antifogging property is not lowered.
Furthermore, the preferred content of colloidal silica in the water-absorbing composite film is 50 to 80 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin from the viewpoint of pencil hardness.

For example, in order to form a water-absorbing composite film on a hard substrate, first, a water-absorbing composite film-forming coating solution is prepared.

The water-absorbing composite film-forming coating solution can be prepared by the following method.
Polyvinyl acetal resin, colloidal silica, and silicon alkoxide are added to the solvent at a predetermined ratio so that the content of these components in the resulting water-absorbing composite film satisfies the above-mentioned requirements. An appropriate amount of an inorganic acid or an organic acid as a decomposition catalyst is added, and various additives are added as necessary to prepare a coating solution for forming a composite film having a solid content concentration of 3 to 20% by mass.

As the solvent in the coating solution, an aqueous solvent that is a mixture of an organic solvent and water is preferable.
As the organic solvent, a polar solvent having miscibility with water such as alcohol, cellosolve, ketone, and ether can be used.
Examples of alcohol solvents include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, etc .; cellosolve solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, and derivatives thereof; ketone solvents Are, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc .; examples of ether solvents include dioxane, tetrahydrofuran, and the like.
These organic solvents may be used individually by 1 type, and may be used in combination of 2 or more types.
The water content is preferably 140 to 720 parts by mass, more preferably 400 to 600 parts by mass with respect to 100 parts by mass of the polyvinyl acetal resin.

In the coating solution, in order to contain a hydrolyzate or partial hydrolyzate of silicon alkoxide, a hydrolysis catalyst for the silicon alkoxide is added.
As the hydrolysis catalyst, it is preferable to use an acid catalyst, particularly an inorganic acid such as hydrochloric acid, nitric acid or sulfuric acid, or an organic acid such as trichloroacetic acid, trifluoroacetic acid, methanesulfonic acid or paratoluenesulfonic acid.
The concentration of the acid catalyst is preferably in the range of 0.001 to 2 mol / kg, expressed by the molar concentration of protons when it is assumed that the protons are completely dissociated from the acid.
The amount of water used for the hydrolysis is preferably 4 times or more, expressed by molar ratio with respect to the total amount of silicon alkoxide.

In the coating solution, various known additives can be blended as necessary within a range that does not impair the object of the present invention. Such additives include glycerin, ethylene glycol, polyethylene glycol, various other surfactants, leveling agents, ultraviolet absorbers, colorants, antifoaming agents, preservatives, silica for improving water absorption performance , Inorganic fillers such as talc, clay and alumina.

The water-absorbing composite film-forming coating solution prepared as described above is preferably stirred at room temperature for a predetermined time to allow the silicon alkoxide to hydrolyze to some extent, and then, on the hard substrate described above at room temperature. Apply.
The coating method is not particularly limited, but from the aspect of productivity, for example, flow coating method, spin coating method or dip coating method, reverse coating method, flexographic printing method, other roll coating method, curtain coating method, Further, a nozzle coating method, a spray coating method, a screen printing method, or the like can be used as appropriate.

Thus, after applying the coating solution on the hard substrate, it is usually dried at room temperature for 5 to 20 minutes, and then subjected to heat treatment (prebaking) at a temperature of 50 to 130 ° C. for 5 to 60 minutes. The thickness of the water-absorbing composite film thus formed is usually about 2 to 10 μm, preferably 2 to 6 μm.

In addition, when the ratio of the inorganic component with respect to polyvinyl acetal resin is increased, if it heats for a long time at high temperature, such as 120 degreeC for 30 minutes, hardening of a film will progress and some film hardness and abrasion resistance will be obtained. However, sufficient antifogging performance may not be obtained. Therefore, the coating skeleton has a certain degree of strength and flexibility by adjusting the heating temperature and time, such as 10 minutes if the heating temperature is 120 ° C and 30 minutes to 60 minutes if the heating temperature is 60 ° C. The coating film can be cured as it is, and the performance of the coating film such as hardness, abrasion resistance, and wet cloth abrasion resistance can be improved while maintaining sufficient antifogging properties.
Further, since the proportion of colloidal silica and silicon alkoxide hydrolyzed or partially hydrolyzed in the film can be increased, the film hardness and sufficient anti-fogging property that the film is not scratched even when the pencil hardness is 4H or higher are provided. It can be set as an anti-fogging film.

(2) Hydrophilic polymer brush The hydrophilic polymer brush immobilized on the water-absorbing composite membrane can be synthesized by, for example, the method described in JP 2010-57745 A. That is, a monomer composition having a hydrophilic group on the surface of a base material (for example, a hard substrate) is polymerized by an atom transfer radical polymerization method (ATRP) in the presence of a polymerization initiator to form a polymer brush on the surface of the base material. It can be manufactured through a step of forming. Since the hydrophilic polymer brush has a structure in which a large number of hydrophilic groups are bonded to the main chain in a brush shape, a surface having a large number of hydrophilic groups per unit area can be obtained. Since such a surface is very hydrophilic, the adsorbed water does not form droplets and spreads in the form of a film, thus preventing fogging.
The hydrophilic group is a hydrophilic group obtained by polymerizing N-methacryloyloxyethyl-N, N-dimethylammonium-α-N-methylcarboxybetaine (hereinafter referred to as CMB) as a monomer. Highly suitable.

The polymerization initiator is preferably an organosilane compound. Examples of organosilane compounds include (11- (2-bromo-2-methyl) propionyloxy) undecyltrichlorosilane, (4- (2-bromo-2-methyl) propionyloxy) butyltrichlorosilane, (6- ( And reactive silane-containing initiators such as 2-bromo-2-methyl) propionyloxy) hexyltrichlorosilane and (8- (2-bromo-2-methyl) propionyloxy) octyltrichlorosilane.

The amount of the polymerization initiator is preferably 0.001 to 10 mol, more preferably 0.01 to 5 mol, per 100 mol of the monomer.

The polymerization of the monomer composition can be performed, for example, by immersing the base material in a mixed solution of the monomer composition, the polymerization initiator, and the organic solvent. When using a substrate having a hydroxyl group such as a glass plate as a substrate and using an organic silane compound as a polymerization initiator, it is preferable to apply a silane coupling treatment to the substrate surface in advance to bond the organic silane compound. . When the hydroxyl group on the substrate surface is not sufficient, it is preferable to provide a primer layer on the substrate surface in advance before attaching the organosilane compound so that the organosilane compound can be bonded at high density.

Although it does not specifically limit as an organic solvent, For example, alcohol, such as water, methanol, ethanol, isopropyl alcohol, ethylene glycol, propylene glycol, ketones, such as acetone and methyl ethyl ketone, alkyl ethers, such as diethyl ether and tetrahydrofuran, benzene And solvents used in usual solution polymerization, such as aromatics such as toluene and xylene, hydrocarbons such as n-hexane and c-hexane, and acetates such as methyl acetate and ethyl acetate. It is preferable to use an organic solvent that has been deaerated beforehand using an inert gas or the like.

The amount of the organic solvent used is preferably adjusted so that the concentration of the monomer composition in the solution containing the monomer composition is 10 to 80% by mass.

Furthermore, during polymerization, a monovalent copper salt such as copper bromide or copper chloride, a polyvalent base such as bipyridyl or trisaminodiethylamine, a free initiator such as ethyl-2-bromoisobutyrate, or the like. You may coexist.

The polymerization conditions such as temperature and time for polymerizing the monomer composition are appropriately selected depending on the type of the polymerizable monomer and the polymerization initiator, and are not particularly limited. The polymerization of the monomer composition is inactive. Although it proceeds even at room temperature in a gas atmosphere, the smaller the amount of unreacted monomer in the resulting polymer, the better. The polymerization of the monomer composition is preferably performed in an atmosphere of an inert gas such as nitrogen gas or argon gas.

The completion of the polymerization reaction and the presence or absence of unreacted monomers in the reaction system can be confirmed by a general analytical method such as gas chromatography.

The weight average molecular weight of the polymer after polymerization of the monomer composition is preferably 1,000 to 1,000,000, more preferably 5000 to 100,000, from the viewpoint of the rheological properties of the polymer, hydrophilicity, and hydrophobic balance. The weight average molecular weight of the polymer is measured by gel permeation chromatography.

(3) Primer layer The primer layer contains, for example, a hydrolyzate or partial hydrolyzate of silicon alkoxide, or colloidal silica together with them. As the primer layer, those having many silanol groups on the surface and water permeability to the underlying water-absorbing composite film are preferable, and hydrolyzate or partial hydrolyzate of silicon alkoxide or colloidal silica is added thereto. Those are preferred.

The amount of silicon alkoxide added to the primer layer forming coating solution is preferably 0.05 to 2.0% by mass, more preferably 0.1 to 1.5% by mass in terms of silica solid content. If the amount of silicon alkoxide added is too small, a sufficient primer layer that can immobilize the polymer brush will not be formed, and if it is too large, the film thickness will be too thick and the water permeability to the water-absorbing composite film will be lost. There is a risk of cracks. By adding an acid catalyst to the coating solution, the hydrolysis of the silicon alkoxide can be promoted, and cracks in the primer layer can be suppressed. However, if the acid concentration becomes too high, handling becomes difficult and workability is reduced. . A preferable addition amount is 0.1 to 4% by mass, and more preferably 0.5 to 2.0% by mass. Further, water may be added as appropriate in accordance with the hydrolysis of the silicon alkoxide, but when the primer layer is formed by drying at room temperature, it may be added without addition or in a small amount.

In order to form a primer layer, first, the coating solution is applied on a glass substrate or a water-absorbing composite film at room temperature. The coating method is not particularly limited, but from the aspect of productivity, for example, flow coating method, spin coating method or dip coating method, reverse coating method, flexographic printing method, other roll coating method, curtain coating method, Further, a nozzle coating method, a spray coating method, a screen printing method, or the like can be used as appropriate. After application, the primer layer can be formed by drying at room temperature or drying by heating. When the coating liquid is absorbed by the water-absorbing composite film on the substrate, the primer layer is applied once and dried, and then the primer layer is applied again to the surface and dried to obtain the necessary primer layer. Can be formed on the water-absorbing composite membrane.

Further, instead of silicon alkoxide, a hydrolyzed solution of ethyl silicate may be used, for example, Colcoat HAS series and Colcoat N-103X. Compared to silicon alkoxide, ethyl silicate hydrolyzate has a high binder property, so that a good primer layer can be formed only by adding a small amount. Further, since the hydrolysis has already been sufficiently performed, it is not necessary to add an acid catalyst. The amount of ethyl silicate hydrolyzed solution added is preferably 0.005 to 0.5% by mass, more preferably 0.01 to 0.2% by mass, based on the primer layer forming coating solution. is there.

It is very effective to add colloidal silica to the primer layer to prevent the primer layer forming coating solution from being absorbed into the water-absorbing composite film and to improve water permeability and abrasion resistance. By adding colloidal silica to the primer layer forming coating solution composed of the above silicon alkoxide, acid catalyst, and alcohol, the coating solution can be prevented from being absorbed into the water-absorbing composite film. A primer layer capable of immobilizing the polymer brush can be formed with the coating. In addition, the colloidal silica forms voids in the primer layer, which not only increases water permeability, but also forms irregularities on the surface, so that the polymer brush enters the dents to improve wear resistance and improve hydrophilicity for a long time. Will be maintained over time. The average particle size of the colloidal silica is preferably in the range of 5 to 50 nm, more preferably in the range of 8 to 20 nm. The amount of colloidal silica added is preferably 0.05 to 2.0% by mass, more preferably 0.1 to 1.0% by mass with respect to the primer layer forming coating solution. . If the amount of colloidal silica added is too small, the above-mentioned effects of water permeability and abrasion resistance cannot be obtained, and if too much, not only the primer layer becomes too thick and water permeability is lost, There is a risk of cracks.

The anti-fogging film of the present invention has a water absorption function (function to prevent water fog by adsorbing water droplets adhering to the film inside) and a hydrophilic function (function to prevent water fog from forming water drops adhering to the film). For example, in an automobile, the anti-fogging property is exhibited by the water absorption function for about 10 seconds to 3 minutes from the time when the surface temperature of the glass inside the vehicle is below the dew point of the atmosphere inside the vehicle (film surface) Since there is no water film), antifogging properties are exhibited by the hydrophilic function thereafter (there is a water film on the film surface), and the effect is exhibited.

[2] Antifogging film-coated article The antifogging film-coated article of the present invention has a hard substrate and the antifogging film of the present invention formed on the hard substrate.
Examples of the hard substrate used as the base material include various mirrors and a translucent hard substrate. There is no particular limitation as the translucent hard substrate, for example, a polycarbonate substrate, a plastic substrate such as an acrylic resin substrate such as a polymethyl methacrylate substrate, or a glass substrate can be used depending on the situation, but in these, From the viewpoint of forming a water-absorbing composite film having high pencil hardness, a glass substrate is preferable.

The glass substrate is a plate glass commonly used for automobiles, buildings, industrial glasses, etc., so-called float glass, etc., various colored glasses such as clear, green, bronze, various functional glasses, tempered glass and the like. In addition to similar glass and laminated glass, various types of flat glass products such as multi-layer glass, flat plates and bent plates can be used.
The plate thickness is, for example, about 1 mm to 12 mm. Particularly, 3 mm to 10 mm is preferable for construction, and 2 mm to 5 mm is preferable for automobiles.

When the polycarbonate substrate or the acrylic resin substrate is used, the plate thickness is usually about 2 to 8 mm, preferably 3 to 6 mm.
Further, in the case of a plastic substrate, for the purpose of improving the adhesion with the water-absorbing composite film provided on the surface, an oxidation method, a concavo-convex method, or the like may be applied to the surface on which the water-absorbing composite film is formed, if desired The surface treatment can be performed. Examples of the oxidation method include corona discharge treatment, plasma treatment, chromic acid treatment (wet), flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, and the like. A processing method etc. are mentioned. These surface treatment methods are appropriately selected depending on the type of plastic substrate to be used. In general, corona discharge treatment is preferably used from the viewpoints of effects and operability.

The anti-fogging film-coated article of the present invention is an article in which a water-absorbing composite film having excellent anti-fogging property and high pencil hardness is provided on a hard substrate, in particular, a light-transmitting hard substrate. And antifogging mirrors for use in bathrooms, toilets, etc., antifogging window glass and antifogging mirrors for automobiles, etc., and antifogging window glass for buildings.

Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In addition, the various characteristics of the glass substrate with an anti-fogging film | membrane obtained in each case were calculated | required by the method shown below.

(1) Appearance Appearance (presence of whitening and cracks) of the coating film of the obtained glass substrate with an antifogging film was visually observed and evaluated according to the following criteria.
A: No problem.
B: Although there are some irregularities on the film surface, there is no practical problem.
C: There is a problem.

(2) Anti-fogging property The occurrence of fogging was evaluated according to the following criteria by an exhalation method in which an anti-fogging film-coated glass substrate was sprayed at room temperature (25 ° C.).
AA: No cloudiness or distortion occurs.
A: There is no clouding at all, but slight distortion occurs.
B: Slight cloudiness or large distortion occurs.
C: Cloudy equivalent to or more than normal glass.

(3) Pencil hardness According to JIS K 5400 paint general test method, the surface of the film was scratched 5 times with a pencil to which a load of 1 kg (9.8 N) was applied, and the film was broken less than 2 times. The hardness was defined as pencil hardness.

(4) Taber abrasion test In the Taber abrasion test, a Taber abrasion tester ("5150 ABRASER" manufactured by TABER INDUSTRIES) was used, and the abrasion test was performed 500 times with a load of 250 g, and the haze value of the coating film before and after the test was measured. . The haze value was measured using “HGM-2DP” manufactured by Suga Test Instruments Co., Ltd., and the difference was 4% or less before and after the test.
A; Pass C; Fail

(5) Packing wear test The pad wearing test was carried out using a wear testing machine (“HEIDON-18” manufactured by Shinto Kagaku Co., Ltd.) and a nell cloth containing 2 cm ³ of water at 25 ° C. was attached, and 0.25 kg / cm ² A wear test was performed 5000 times with a load of 5 to evaluate the appearance and antifogging properties of the coating. The appearance evaluation criteria were the same as (1), and the antifogging evaluation criteria were the same as (2).
In addition, it can be evaluated by this test how much excellent anti-fogging property can be maintained.

(Preparation of water-absorbing composite film-forming coating solution)
Each component constituting the water-absorbing composite film-forming coating solution is placed in a glass container so as to have the ratio shown in Table 1 below, and stirred at room temperature for about 3 hours, and then the water-absorbing composite film-forming coating solution. Got. SREC KX-5 (polyvinyl acetal resin) and Snowtex OS (colloidal silica) were adjusted so that the solid content concentrations in the coating liquid were 3.5% by mass and 2.25% by mass, respectively (Table 1). Numerical values in parentheses, and in Table 2 described later, the numerical values in parentheses indicate the solid content concentration, and TEOS indicates the solid content concentration in terms of silica).

Each component shown in Table 1 is as follows.
Solmix AP-7: alcohol solvent (manufactured by Nippon Alcohol Industry)
-SREC KX-5: Polyvinyl acetal resin: (manufactured by Sekisui Chemical Co., Ltd., solid content 8%),
Snowtex OS: colloidal silica (Nissan Chemical Industries, Amorphous silica 20%, particle size 8-11 nm),
TsOH: p-toluenesulfonic acid (manufactured by Kanto Chemical Co., Inc.)
TEOS: Tetraethoxysilane (Shin-Etsu Silicone, KBE-04),
・ KP-341: Leveling agent (Shin-Etsu Silicone)

(Preparation of primer forming coating solution)
Each component constituting the primer forming coating solution was put in a glass container so as to have the ratio shown in Table 2 below, and stirred at room temperature for about 3 hours to obtain primer forming coating solutions 1 to 5. . Snowtex OS (colloidal silica), HAS-6 (binder), and N-103X (binder) have solid content concentrations in the coating liquid of 0.5% by mass, 0.025% by mass, and 0.10%, respectively. %.

Each component shown in Table 2 is as follows (those described in Table 1 are omitted).
HAS-6: ethyl silicate hydrolyzate (manufactured by Colcoat)
N-103X: ethyl silicate hydrolyzate (manufactured by Colcoat)
・ HCl (hydrochloric acid) (Kishida Chemical Co., Ltd.)

(Example 1)
The coating solution for forming a water-absorbing composite film shown in Table 1 was applied by flow coating on a washed soda-lime silicate glass substrate (100 × 100 mm) in an environment of humidity 30% and room temperature 20 ° C. After drying for about 10 minutes under the same environment, the glass substrate with a water-absorbing composite film was obtained by heating and drying for 10 minutes in a clean oven set at 120 ° C.
Next, the primer layer forming coating solution 1 shown in Table 2 was applied on the formed water-absorbing composite film by the flow coating method, dried for about 5 minutes, and then again the primer forming solution was applied by the flow coating method. After applying for about 5 minutes and drying for about 5 minutes, it was heated and dried in a clean oven set at 120 ° C. for 30 minutes to form a primer layer on the water-absorbing composite film.

Next, a hydrophilic polymer brush was formed on the formed primer layer as described below [Step 1: Silane coupling treatment to substrate surface]
18.1 g (40 mmol) of (11- (2-bromo-2-methyl) propionyloxy) undecyltrichlorosilane (Br-PUCS) was dissolved in 150 mL of toluene to prepare a coupling solution. A glass substrate with a primer layer formed on a water-absorbing composite film is placed in a sample bottle, a coupling solution is added so that the glass substrate is completely immersed, the lid is covered, and the mixture is reacted at room temperature for 18 hours. Take out, wash with toluene, and dry with nitrogen gas, and bond Br-PUCS which is a polymerization initiator on the primer layer.

[Step 2: Polymerization of CMB on primer layer]
In a sample bottle, 309 mg (2.143 mmol) of copper bromide (CuBr), 670 mg (4.286 mmol) of 2,2′-bipyridyl and N-methacryloyloxyethyl-N, N-dimethylammonium-α-N-methylcarboxybetaine (CMB) 10.07 g (43.17 mmol) was added, and ethyl-2-bromoisobutyrate 320 μL (2.143 mmol), 100 mL of methanol degassed by argon gas bubbling, and silane coupling treatment in Step 1 were performed. A glass substrate was inserted, air was expelled with argon gas, the lid was closed, and atom transfer radical polymerization (ATRP) was started. Ethyl-2-bromoisobutyrate was used as a free initiator to obtain free CMB polymer. After 6 hours, the lid is opened and the reaction is terminated by contacting (deactivating) the air and the solution. The glass substrate is taken out, washed with ethanol and water, dried with nitrogen gas, and the CMB polymer chain on the outermost surface. A glass substrate with an antifogging film having a hydrophilic polymer brush made of

For the purpose of grasping the molecular weight of the polymer brush portion of the CMB obtained in the above-mentioned step 2, a CMB polymer was synthesized alone without using glass with Br-PUCS attached.
Specifically, 30.9 mg (0.2143 mmol) of copper bromide (CuBr), 67.0 mg (0.4286 mmol) of 2,2′-bipyridyl and 1.007 g (4.317 mmol) of CMB were placed in a sample bottle, and ethyl-2 -32 μL (0.2143 mmol) of bromoisobutyrate and 10 mL of methanol degassed by argon gas bubbling were added, air was purged with argon gas, the lid was closed, and atom transfer radical polymerization (ATRP) was started. After 6 hours, the lid was opened, the air and the solution were contacted (deactivated) to terminate the reaction, and a free CMB polymer was obtained. The obtained CMB polymer had a weight average molecular weight Mw of 15600 and an n number (degree of polymerization) of 43.52 on average. Therefore, it is presumed that polymer chains having an n number of CMB of 43.52 are also arranged on the glass substrate surface with the antifogging film.

(Examples 2 to 5)
Antifogging in the same manner as in Example 1 except that the primer layer forming coating solutions 2 to 5 (corresponding to Examples 2 to 5 respectively) shown in Table 2 were applied on the water-absorbing composite film by the flow coating method. A glass substrate with a film was obtained.

(Comparative Example 1)
In the same manner as in Example 1, a glass substrate with a water-absorbing composite film was obtained.
Next, a solution diluted with water so that the concentration of the surfactant (manufactured by NOF Corporation, trade name “RAPISOL A-30”) was 5.0% by mass was applied to the surface of the produced water-absorbing composite membrane. Then, it heat-dried for 30 minutes in the clean oven set to 120 degreeC, and obtained the glass substrate with an anti-fogging film | membrane.

The evaluation results of various properties of the glass substrates with antifogging films obtained in Examples 1 to 5 and Comparative Example 1 are shown in Table 3 below.

In the antifogging film obtained in Example 1, no irregularities, unevenness, whitening, cracks, etc. were observed in the appearance, and a good coating film free from fogging by breath was obtained. When the pencil hardness of the obtained coating film was measured, a film hardness of 6H was obtained, and when a Taber abrasion test was performed, no film peeling occurred, and the difference in haze value before and after the test was 4% or less. A coating film having excellent properties could be obtained. Evaluation of anti-fogging properties after the compressive wear test showed that the surface hydrophilicity was maintained even though slight exhalation caused distortion due to cloudiness and water film non-uniformity, and formed on the water-absorbing composite film. It was confirmed that the polymer brush was crosslinked by the primer layer. Moreover, peeling, a crack, and a crack were not seen in the coating-film external appearance after a test.

In the antifogging film obtained in Example 2, no irregularities, unevenness, whitening, cracks, etc. were observed in the appearance, and a good coating film free from fogging by exhalation was obtained. When the pencil hardness of the obtained coating film was measured, a film hardness of 6H was obtained, and when a Taber abrasion test was performed, no film peeling occurred, and the difference in haze value before and after the test was 4% or less. A coating film having excellent properties could be obtained. When the antifogging property after the compressive wear test was evaluated, the antifogging property was maintained even though slight exhalation caused distortion due to the non-uniformity of the water film. By adding colloidal silica, the antifogging wear resistance was maintained. Improved. Moreover, peeling, a crack, and a crack were not seen in the coating-film external appearance after a test.

In the anti-fogging films obtained in Examples 3, 4 and 5, the same results were obtained, and the coating film had no irregularities, unevenness, whitening or cracks in its appearance, and was a good coating film that was not fogged by exhalation. was gotten. Further, when the pencil hardness of the obtained coating film was measured, a film hardness of 9H was obtained, and in the Taber abrasion test, no film peeling occurred and the difference in haze value before and after the test was 4% or less. An excellent coating film could be obtained. Furthermore, when the antifogging property after the compressive wear test was evaluated, no fogging or distortion occurred, the excellent antifogging property was maintained, and no peeling, scratches or cracks were observed in the coating film appearance.

Comparative Example 1 has a film hardness of about 6H pencil hardness and abrasion resistance that can withstand the Taber abrasion test, but the hydrophilicity of the coating surface is due to the surfactant dispersed in the coating, The anti-fogging performance could not be maintained because the surfactant flowed out by the abrasion test.

Claims

An anti-fogging film comprising a water-absorbing composite film comprising a polyvinyl acetal resin, a hydrolyzate or partial hydrolyzate of silicon alkoxide, and colloidal silica, and a hydrophilic polymer brush fixed on the water-absorbing composite film. .
The antifogging film according to claim 1, further comprising a primer layer between the water-absorbing composite film and the hydrophilic polymer brush.
The anti-fogging film according to claim 2, wherein the primer layer contains a hydrolyzate or a partial hydrolyzate of ethyl silicate.
The anti-fogging film according to claim 2, wherein the primer layer contains a hydrolyzate or partial hydrolyzate of silicon alkoxide.
The antifogging film according to claim 3 or 4, wherein the primer layer further contains colloidal silica.
The water-absorbing composite film is composed of 30 to 80 parts by mass of colloidal silica and 5 to 55 parts by mass of silica-converted particles derived from silicon alkoxide hydrolyzate or partial hydrolyzate with respect to 100 parts by mass of the polyvinyl acetal resin. The antifogging film according to any one of claims 1 to 5, comprising
An antifogging film-coated article comprising: a hard substrate; and the antifogging film according to any one of claims 1 to 6 formed on the hard substrate.
The anti-fogging film-coated article according to claim 7, wherein the hard substrate is a mirror or a translucent hard substrate.