JP2001293825A - Antifogging base material and method for forming the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antifogging base material excellent in antifogging properties, water wiping resistance and abrasion resistance and capable of keeping antifogging capacity over a long period of time. SOLUTION: The antifogging base material is obtained by laminating a protective film with a thickness of 3-10 nm having water permeability to a water absorbable composite film comprising a mixture of a polyvinyl acetal resin with a degree of acetalization of 10 mol% or less and a hydrolysate or partial hydrolysate of silyl isocyanate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be used for various applications such as anti-fog mirrors for bathrooms and lavatories, anti-fog window glasses for automobiles or anti-fog mirrors, anti-fog window glasses for buildings and the like. The present invention relates to a possible antifogging substrate and a method for forming the same.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 5-51471 discloses an antifogging substrate composed of a single-layer film using a water-absorbing polymer, in which the surface layer comprises a polymer compound having a -P = N-skeleton. Disclosed is a coated laminate provided with anti-fogging properties, which is obtained by providing, as a curable coating, a polyvinyl alcohol having a saponification degree of 70 mol% or more and an average polymerization degree of 300 or more and a crosslinking agent on a substrate. And Japanese Patent Application Laid-Open
JP-A-157794 discloses a coating-type anti-fog agent which is applied with only a polyvinyl acetal resin and then dried at normal temperature to form an anti-fog film. JP-A-6-158031 discloses a coating type anti-fog agent. Providing an antifogging layer made of a polyvinyl acetal resin having a degree of acetalization of 2 to 40 mol% on the surface of an article such as a plastic film, or
Disclosed is an antifogging article in which a water-soluble resin layer is provided on the surface of an article, and an antifogging layer made of a polyvinyl acetal resin having an acetalization degree of 2 to 40 mol% is provided thereon.

JP-A-10-212471 discloses an antifogging agent comprising polyvinyl alcohol, which is an organic substance having a hydroxyl group, tetramethoxysilane, which is a metal organic compound, and hydrochloric acid, which is a catalyst for condensation polymerization of these compounds. Is disclosed.

Japanese Unexamined Patent Publication (Kokai) No. Hei 9-136374 discloses a laminated antifogging base material comprising a first layer containing hydrophilic inorganic fine particles and a coupling agent on a molded resin substrate, and a hydrophilic layer. JP-A-11-84102 discloses a resin molded product having antifogging maintenance property, which is provided with a second layer made of a conductive resin and / or a surfactant.
Patent Document 1 discloses an antifogging coating characterized in that at least one water-absorbing polymer selected from polyacrylic acids and polyvinyl alcohol is used as an inner layer on the surface of an optical substrate, and an outer layer is formed of a porous film. An optical component using is disclosed.

[0005]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open No. 5-51471 or Japanese Patent Application Laid-Open No. 6-15779
No. 4, JP-A-6-158031, JP-A-10
JP-A-212471 and JP-A-9-136374 have excellent antifogging performance due to the structure in which the water-absorbing polymer resin is exposed to the surface, but have abrasion resistance during drying. The abrasion resistance when absorbing moisture tends to be further deteriorated, making it difficult to use on articles that are wiped on a daily basis, and the addition of a curable additive to enhance the abrasion resistance provides anti-fog performance , It is not possible to obtain good scratch resistance and antifogging property. Also, JP-A-11-8
In JP-A No. 4102, the film thickness of the outer layer is not specified, but in order to obtain a porous film from the intended use, it is limited to a specific film forming method.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is directed to a polyvinyl acetal resin having water absorbency on a substrate surface and a silyl isocyanate or a partial hydrolysis thereof. Forming a water-absorbing composite film made of a material, and further laminating a water-permeable protective film on the upper layer by controlling a water-repellent silica compound so that the film thickness becomes a single molecule level of 10 nm or less. As a result, an antifogging substrate having excellent antifogging properties, water wiping resistance, and abrasion resistance and capable of maintaining antifogging performance for a long period of time, and a method for forming the same have been developed.

That is, the antifogging substrate of the present invention comprises a water-absorbing composite membrane comprising the following components A and B, which are polyacetal resins, mixed on the surface of the substrate; 3 to 10 n thick
m protective films are laminated. A component: a polyvinyl acetal resin having an acetalization degree of 10 mol% or less B component: a silyl isocyanate represented by the general formula Si (NCO) ₄ , a hydrolyzate of the silyl isocyanate,
Any one or more of the partial condensates The anti-fogging substrate of the present invention is such that the water-absorbing composite film has a weight ratio of polyvinyl acetal resin of 95.0 wt%.
-99.5% by weight of silyl isocyanate, a hydrolyzate of the silyl isocyanate and a partial condensate thereof in an amount of 0.5% by weight to 5.0% by weight in terms of silyl isocyanate.

Further, the antifogging substrate of the present invention is characterized in that the protective film comprises a silica compound having water repellency.

Further, the method for forming an antifogging substrate of the present invention comprises the steps of:
In forming the above antifogging substrate, (a) a step of preparing a substrate, (b) a polyvinyl acetal resin having an acetalization degree of 10 mol% or less, and a general formula Si (NCO)
_{At least one} of the silyl isocyanate represented by ₄ , a hydrolyzate of the silyl isocyanate, and a partial condensate thereof is added to a solution containing a solvent and mixed to prepare a coating solution for a water-absorbing composite film. (C) applying the coating solution on the surface of the base material, and heat-treating the coating solution at a low temperature of at least 90 ° C. to 150 ° C. to form a water-absorbing composite film;
(D) a step of applying a silica compound having water repellency to the upper layer of the water-absorbing composite film and heat-treating it at a low temperature of at least 90 ° C. to 150 ° C. to form a protective film. It is characterized by forming a cloudy cured film.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The polyvinyl acetal resin which is one of the components forming the water-absorbing composite film of the present invention includes:
By using a polyvinyl acetal resin having an acetalization degree of 10 mol% or less, a good antifogging transparent film can be formed. If the degree of acetalization of the polyvinyl acetal resin is 10 mol% or more, the antifogging property is poor, and fogging is likely to occur, which is not preferable.

As the other component forming the water-absorbing composite film, silyl isocyanate represented by the general formula Si (NCO) ₄ , a hydrolyzate of the silyl isocyanate, and a partial condensate thereof can be used. In addition, these components are excellent in binding properties with the polyvinyl acetal resin, anti-fog properties, and in order to improve various physical properties such as water wiping resistance in a well-balanced manner, the polyvinyl acetal resin and the silyl isocyanate are contained in the water-absorbing composite film. The weight ratio is preferably 95.0: 5.0 to 99.5: 0.5, and when the ratio is less than 0.5 wt%,
If the film strength is weakened, the water wiping resistance is deteriorated. If it exceeds 5.0 wt%, the antifogging property is deteriorated and the liquid stability after blending is deteriorated.

Each of the raw materials for forming the above-mentioned water-absorbing composite film is added to a diluting solvent, and if necessary, a leveling agent is further added to prepare a coating solution. Water and alcohol-
Preferred solvents are, for example, methanol, ethanol, propanol, ethylene glycol, propylene glycol, hexylene glycol, and esters such as ethyl acetate, butyl acetate and amyl acetate. In addition, a suitable amount of methyl silicones such as dimethyl silicone may be added as a leveling agent with a cellosolve such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve, or a mixed solvent thereof. An alcohol-based or cellosolve-based one or a mixture originally contained in the solution may be selected in consideration of the evaporation rate and the film viscosity of the solution.

Next, these are applied as a coating solution on a substrate. Known application methods such as dip coating, flow coating, spin coating, roll coating, spray coating, screen printing, and flexographic printing can be used as the application means. After coating, by heating at a relatively low temperature of 90 ° C. to 150 ° C. for about 30 minutes to 60 minutes, most of the solvent is scattered, and at the same time, silyl isocyanate, a hydrolyzate of the silyl isocyanate, and a partial condensate thereof are formed. Acts as a matrix. The water-absorbing composite film has a high film strength because the OH group of the polyvinyl acetal resin and the isocyanate group of the silyl isocyanate are cross-linked and strongly bonded.

The thickness of the water-absorbing composite membrane is preferably at least 3 μm after the heat treatment, and if it is less than 3 μm,
The antifogging durability tends to be poor. The thickness is preferably 3 to 60 μm, more preferably 10 to 30 μm.
μm.

Next, a protective film is coated on the water-absorbing composite film obtained above. As the protective film, a silane compound having water repellency is preferably used because the scratch resistance and the water wiping resistance can be improved. The silica compound is not particularly limited, and may be a compound represented by the general formula (CH ₃ ) _N S
Alkylchlorosilane represented by iCl _4-n (where n is 1-2), general formula (CH ₃ ) _n SiR _4-n (where n is 1-2 and R is alkoxy having 1-5 carbon atoms) An alkylalkoxysilane represented by the general formula CF ₃ (CF ₂ ) _n C
H ₂ CH ₂ SiX ₃ (where n is 0 to 9, X is a chlorine group or an alkoxy group having 1 to 5 carbon atoms) fluoroalkyl silane represented by the general formula CH ₃ HSiX ₂ (X is a chlorine group or a carbon A methylhydrogensilane represented by the following formula (CH ₃ ) ₃ SiNH:
Si (CH ₃₎ hexamethyldisilazane represented by _3, the general formula _{(CH 3) n Si (CNO} ) 4-n ( where n is 1 to
And alkylsilyl isocyanate represented by 2), including their hydrolysates and partial condensates,
One or two or more can be used in combination. further,
In order to accelerate the curing reaction of these water-repellent silica compounds at a temperature at which the water absorbing performance is not reduced, it is preferable to add a curing catalyst.

The curing catalyst includes a chelating agent, an acid and a metal salt. Among them, chelating agents include aluminum chelate compounds such as aluminum ethyl acetoacetate isopropylate, aluminum tris (ethyl acetoacetate), aluminum tris (acetylacetonate), aluminum bisethylacetoacetate monoacetylacetonate, and di-iso- Titanium chelate compounds such as propoxy bis (acetylacetonato) titanium and iso-propoxy (2-ethylhexanediolato) titanium.

Examples of the acid include inorganic acids such as nitric acid and hydrochloric acid, and organic acids such as acetic acid, maleic acid and citric acid. Further, examples of the metal salt include sodium acetate, sodium aluminate, sodium zirconate, cobalt naphthenate and the like. These curing catalysts include 1
Species can be used alone or in combination of two or more. The raw material for forming the protective film is added to a solvent such as water, alcohol, ester or hydrocarbon, and if necessary, a leveling agent is added and mixed to form a coating liquid.

Next, these are applied as a coating solution on a glass substrate. Known application methods such as dip coating, flow coating, spin coating, ruul coating, spray coating, screen printing, and flexographic printing can be adopted as the application means. After application, at a relatively low temperature of 90 ° C to 150 ° C,
By heating for about 0 to 60 minutes, almost all of the solvent is scattered and a cured film is formed at the same time. Further, the thickness of the protective film is preferably reduced to a monomolecular level of 3 to 10 nm in order to utilize the water permeability obtained from the three-dimensional structure of the film after the heat treatment. Fogging performance is inferior.

As a substrate used in the present invention, glass is typically used, and the glass is a sheet glass generally used for automobiles, architectural and industrial glass, so-called float sheet glass, and the like. It can be used as various types of colored glass such as clear, green, bronze, etc., various functional glass, tempered glass and similar glass, laminated glass, multi-layer glass, etc., as well as various flat glass products such as flat or bent plates. Needless to say. The plate thickness is, for example, about 1.0 mm or more and about 12 mm or less, and about 3.0 m for architectural use.
The glass is preferably about 2.0 mm or more and about 10 mm or less, and is about 2.0 mm or more and about 5.0 mm or less for automobiles. In addition, since an antifogging film can be formed on the surface of a substrate such as glass or plastic at a relatively low temperature, for example, mirror-finished glass, bending and molding of automotive glass, etc. It is also possible to easily form a film. Further, the substrate of the present invention is not limited to glass, and other than glass, resins, metals, ceramics, and the like can be used as long as they do not deteriorate even after being dried in the above temperature range.

[0020]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited to such an embodiment.

The antifogging optical parts having an antifogging film obtained in the present invention and comparative examples were measured for various physical properties by the following measuring methods. [Repeated anti-fogging property]: The degree of fogging when kept in steam of warm water set at 43 ° C. for 3 minutes according to “JIS S 4030 Eyeglass Antifogging Agent Test Method”, and the room temperature (23
(° C., 63% RH), the degree of fogging due to the exhaled air was observed, and this operation was performed up to 10 cycles. [Cooling / anti-fogging property]: After keeping the anti-fogging optical component in a refrigerator set at 4 ° C. for 30 minutes, normal temperature (23 ° C., 63% RH)
The appearance, the degree of fogging, and the fogging due to exhalation when the inside was taken out were observed, and this operation was performed up to 10 cycles. [Water resistance]: The sample was immersed in distilled water at room temperature (23 ± 2 ° C.) for 6 hours. [Water resistance]: The surface of the anti-fogging film was wiped with a cloth soaked in water and squeezed. The degree of fogging due to exhalation was observed every 10 times. did. [Traverse abrasion]: Load 1 using canvas cloth
A traverse test was performed at 00 g / cm ² , and the appearance was observed and the degree of cloudiness due to exhalation was observed every 300 times.
A sample which passed no traverse and showed no abnormality in appearance and no fogging was judged as acceptable.

Example 1 (Preparation of Chemical Solution for Water Absorbent Composite Membrane) A polyvinyl acetal resin having a degree of acetalization of 8 mol% (trade name "KX-1", solid content 8%, manufactured by Sekisui Chemical) as a water absorbing resin, Silyl isocyanate (trade name “Orgatics SI-40”
0 ", solid content 100%, manufactured by Matsumoto Pharmaceutical Co., Ltd.) was prepared using a mixed solvent of ethanol and water to a solid content concentration of 3 wt%.

The weight ratio of the hydrolyzate or partial hydrolyzate of polyvinyl acetal resin and silyl isocyanate in the water-absorbent composite film after film formation is 98.5 wt%:
A chemical solution for a water-absorbing composite membrane was prepared by adding a mixed solvent to 1.5 wt% and performing a mixing treatment.

(Formation of a water-absorbing composite film) A glass plate having one side masked is immersed in a dipping tank using the chemical solution as a coating solution, and the glass plate is coated by dipping and pulled up. By heating and drying for about 30 minutes, a film having a thickness of 9.5 μm was formed.

(Formation of Chemical Solution for Protective Film) An Al-based curing catalyst was added to a water-repellent hexamethyldisilazane + dimethylsilicone composite chemical solution (trade name "KPN-3504", solid content 100%, manufactured by Shin-Etsu Chemical Co., Ltd.). Thus, a chemical solution for a protective film was obtained.

(Formation of Protective Film) In a dipping tank using this chemical solution as a coating liquid, a moisture-absorbing film-formed plate with the anti-hygroscopic film-formed surface masked is applied by a dipping method, and the glass plate to be coated is applied. By heating and drying at 120 ° C. for about 30 minutes, a water-permeable film having a thickness of 10 nm was formed. As shown in Table 1, it was confirmed that the glass having the antifogging film obtained by the above method was a glass excellent in various antifogging performance, abrasion resistance and appearance.

[0027]

[Table 1]

Example 2 The weight ratio of polyvinyl acetal resin to silyl isocyanate in the water-absorbing composite film was 99.5 wt%: 0.5 wt.
%, And a film having a water-absorbing composite film thickness of 8 μm and a protective film thickness of 10 nm was formed in the same manner as in Example 1 except that the film thickness was adjusted to be 0.1%. The evaluation results were as excellent as in Example 1.

Example 3 A water-absorbing composite film having a thickness of 13 μm was prepared in the same manner as in Example 1, except that the weight ratio of the polyvinyl acetal resin and the silyl isocyanate in the water-absorbing composite film was adjusted to 95 wt%: 5 wt%. Then, a film having a protective film thickness of 10 nm was formed. The evaluation results were as excellent as in Example 1.

Example 4 The same procedure as in Example 1 was repeated except that a methylsilyl triisocyanate-based coating agent (trade name "SIC-003" manufactured by Matsumoto Pharmaceutical Co., Ltd.) was used as a protective film to form a water-absorbing composite film having a thickness of 11 μm. A film having a protective film thickness of 10 nm was formed. The evaluation results were as excellent as in Example 1.

Example 5 A dimethyl silicone-based chemical solution (trade name "KF
Example 9 except that “-9901” manufactured by Shin-Etsu Chemical Co., Ltd.) was used.
A film having a water-absorbing composite film thickness of 12 μm and a protective film thickness of 10 nm was formed in the same manner as described above. The evaluation results were as excellent as in Example 1.

Comparative Example 1 A water-absorbing composite film having a thickness of 7 μm and a protective film having a thickness of 10 nm were formed in the same manner as in Example 1 except that the chemical solution for the water-absorbing composite film was made of a polyvinyl acetal resin alone. did. The evaluation results indicate that the traverse abrasion was 300
After the test, countless scratches were found on the surface. In addition, with respect to water wiping resistance, the film was peeled off by wiping 10 times.

Comparative Example 2 A water-absorbing composite film having a thickness of 7 μm and a protective film having a thickness of 2 nm were formed in the same manner as in Example 1, except that the thickness of the protective film was adjusted to 2 nm. As a result of the evaluation, in the traverse abrasion, countless scratches were confirmed on the surface after 600 tests. Also, with respect to water wiping resistance, the film was peeled off after 30 wiping operations.

Comparative Example 3 A water-absorbing composite film having a thickness of 7 μm and a protective film having a thickness of 20 nm were formed in the same manner as in Example 1 except that the thickness of the protective film was adjusted to 20 nm. As a result of the evaluation, fogging occurred due to exhalation in the initial antifogging property.

Comparative Example 4 A resin having a degree of acetalization of 70 mol% or more (manufactured by Sekisui Chemical Co., Ltd.)
The same operation as in Example 1 was carried out except that the trade name “ESLEK KS-5”) was used, and the water-absorbing composite film thickness was 6 μm.
A protective film having a thickness of 10 nm was formed. As a result of the evaluation, fogging occurred due to exhalation in the initial antifogging property.

Comparative Example 5 A polyvinyl alcohol resin was used in place of the polyvinyl acetal resin in the chemical solution for the water-absorbing composite membrane, except that a polyvinyl alcohol resin was used.
The same operation as in Example 1 was performed, and the thickness of the water-absorbing composite film was about 6 μm.
m, a protective film having a thickness of 10 nm was formed. The evaluation result was that the film was peeled off by wiping 20 times in terms of water wiping resistance. Also, in the water resistance test, clouding due to exhalation occurred even when the test was left for one day or more after the test.

COMPARATIVE EXAMPLE 6 A hygroscopic film having a thickness of 7 was obtained in the same manner as in Example 1 except that the protective film was not formed and a water-absorbing composite film was used as a single-layer film.
A μm membrane was obtained.

As the evaluation results, in the traverse abrasion, countless scratches were confirmed on the surface after 300 tests. Also, with respect to water wiping resistance, the film was peeled off by wiping 20 times.

[0039]

As described in detail above, according to the present invention,
The water-absorbing composite film has a strong film strength because the OH group of the polyvinyl acetal resin and the isocyanate group of the silyl isocyanate are cross-linked and strongly bonded, and the upper layer of the water-absorbing composite film has water repellency. And the film thickness is 10
Since a monomolecular-level water-permeable protective film of nm or less is laminated, the antifogging property, water wiping resistance, and abrasion resistance are excellent, and it is possible to maintain the antifogging performance for a long period of time. It can be widely used for mirrors and the like. Furthermore, since an anti-fog coating can be formed on the surface of a substrate such as glass or plastic at a relatively low temperature, for example, mirror-finished glass, bending and molding of automotive glass, etc. This has the advantage that the film can be formed easily and easily.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02B 1/10 G02B 1/10 Z F term (Reference) 2K009 BB02 CC32 CC42 DD02 EE02 4D075 BB21Z CA39 DA06 DB13 DC13 EB02 EB19 4F100 AA20B AG00C AH02A AH02H AH03A AH03H AH06A AH06H AK23A AK52B AR00B AT00C BA02 BA03 BA07 BA10A BA10B BA10C CC00A CC00B EH461 EH462 EJ421 EJ422 GB07 GB32 JA20BJBYAJ05B06A06

Claims (4)

[Claims] 1. A water-absorbing composite film comprising a polyvinyl acetal resin shown below and a component B which is a silyl isocyanate mixed on the surface of a base material, and a water-permeable protective film having a thickness of 3 to 10 nm. An antifogging base material comprising a film and a laminated film. A component: a polyvinyl acetal resin having an acetalization degree of 10 mol% or less B component: a silyl isocyanate represented by the general formula Si (NCO) ₄ , a hydrolyzate of the silyl isocyanate,
Any one or more of the partial condensates 2. The water-absorbing composite membrane contains polyvinyl acetal resin in a weight ratio of 95.0 wt% to 99.5 wt%,
The antifogging substrate according to claim 1, wherein the silyl isocyanate is comprised of 0.5 wt% to 5.0 wt%. 3. The antifogging substrate according to claim 1, wherein the protective film is a silica compound having water repellency. 4. A process for preparing the antifogging substrate according to claim 1, wherein (a) a step of preparing the substrate; and (b) a polyvinyl acetal resin having an acetalization degree of 10 mol% or less.
Adding at least one of a silyl isocyanate represented by the general formula Si (NCO) ₄ , a hydrolyzate of the silyl isocyanate, and a partial condensate thereof to a liquid containing a solvent,
(C) applying the coating solution on the surface of the base material and heat-treating the coating solution at a low temperature of 90 ° C. to 150 ° C. to form a water-absorbing composite film; d) coating a water-repellent silica compound on the upper layer of the water-absorbing composite film and heat-treating the film at a low temperature of 90 ° C. to 150 ° C. to form a protective film. A method for forming an antifogging substrate, comprising forming a cured film.