JP2001146585A - Antifogging substrate and forming method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antifogging film which is excellent in antifogging properties and resistances to abrasion and wiping with water and can retain antifogging properties over a long time. SOLUTION: This antifogging film comprises (A) a composite water-absorbent film formed from a mixture comprising a polyvinyl acetal resin having a degree of acetalization of 10 mol% or lower and a hydrolyzate or partial hydrolyzate of an alkylsilyl isocyanate and (B) a water-permeable protective film formed thereon with a thickness of 3-10 nm.

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.

In Japanese Patent Application Laid-Open No. H11-84102, the 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.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is directed to a hydrolyzate of a polyvinyl acetaal resin having a water absorbing property on the surface of a substrate and an alkylsilyl isocyanate. Alternatively, a water-absorbing composite film composed of a partial hydrolyzate is formed, and a monomolecular-level water-permeable protective film having a film thickness of 3 to 10 nm is further laminated thereon to provide anti-fogging property, water wiping resistance, and water resistance. Excellent abrasion,
An antifogging substrate 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 hydrolyzate or a partial hydrolyzate of an A component consisting of a water-absorbing polyvinyl acetal resin and an alkylsilyl isocyanate on the surface of the substrate. A water-absorbing composite membrane in which the component B is mixed, and a film thickness 3 having water permeability.
And a protective film having a thickness of 10 to 10 nm. A component: polyvinyl acetal resin having a degree of acetalization of 10 mol% or less B component: General formula R2 _n SiR1 _4-n (wherein, R1 is a carbon atom having 1 carbon atom)
Or an alkyl group of 2, R2 is an isocyanate group, and n is 1 or 2). A hydrolyzate or partial hydrolyzate of an alkylsilyl isocyanate represented by the formula (1): Is from 95% by weight to 9% by weight of polyvinyl acetal resin.
It is characterized in that it contains 9 wt% and a hydrolyzate or partial hydrolyzate of alkylsilyl isocyanate in an amount of 1 wt% to 5 wt%.

Further, in the antifogging substrate of the present invention, the protective film has a general formula of R2 _n SiR1 _4-n (wherein R1 has 1 or 2 carbon atoms).
R2 is an isocyanate group, and n is 1 or 2. ) Is characterized by comprising a hydrolyzate or a partial hydrolyzate of the alkylsilyl isocyanate represented by the formula (1).

[0010] The method for forming the antifogging substrate of the present invention comprises:
Upon forming the antifogging base material, (a) preparing a substrate, and (b) the degree of acetalization less 10 mol% polyvinyl acetal resin of the general formula R2 _n SiR1 _4-n
(Wherein, R 1 is an alkyl group having 1 or 2 carbon atoms, R 2 is an isocyanate group, and n is 1 or 2), and the mixture is added to a solution containing a solvent and mixed to absorb water. Preparing a coating solution for the hydrophilic composite film, and (c) applying the coating solution on the surface of the base material;
A step of forming a water-absorbing composite film by heat treatment at a low temperature of at least 90 ° C. to 150 ° C., and (d) forming a general formula R2 _n SiR1 _4-n (where R1 is carbon An alkyl group of the formula 1 or 2, R2 is an isocyanate group, n is 1
Or 2) is coated with an alkylsilyl isocyanate, and heat treated at a low temperature of at least 90 ° C. to 120 ° C. to form a protective film, thereby forming a hardened antifogging film on the substrate surface. It is characterized by the following.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As a polyvinyl acetal resin which is one of the components forming a water-absorbing composite film, a good anti-fog transparent film is formed by using a polyvinyl acetal resin having an acetalization degree of 10 mol% or less. can do. 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. The water absorption indicates the ability to take in moisture inside the substance (polyvinyl acetal resin film). The higher the water absorption, the greater the amount of water allowed to work on the film, so that the time until dew condensation after supersaturation is reached. become longer. In addition, in normal use, the worked water is released again, so that the antifogging property can be repeatedly maintained.

The raw material of the hydrolyzate or partial hydrolyzate of alkylsilyl isocyanate, which is the other component forming the water-absorbing composite film, is represented by the general formula R2 _n SiR
14 _-n (wherein R1 is an alkyl group having 1 or 2 carbon atoms, R2
Is an isocyanate group, and n represents 1 or 2). These components are excellent in binding properties with polyvinyl acetal resin, and in balance with various physical properties such as anti-fogging property and water wiping resistance, a hydrolyzate or partial hydrolysis of polyvinyl acetal resin and alkylsilyl isocyanate. The weight ratio of the substance in the water-absorbing composite membrane is preferably from 95: 5 to 99: 1. If the weight ratio is less than 1 wt%, the strength of the membrane is weakened, and the water wiping resistance is deteriorated. %, The antifogging property is inferior.

Next, 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 added and mixed to form a coating solution. As the diluting solvent, water and an alcohol-based solvent are preferable, and specific examples thereof include methanol, ethanol, propanol, ethylene glycol, propylene glycol, hexylene glycol, and furthermore. Ethyl acetate, butyl acetate, esters such as amyl acetate, furthermore, methylcellosolve, ethyl cellosolve, cellosolves such as butyl cellosolve and a mixed solvent thereof, and a suitable amount of methyl silicones such as dimethyl silicone as a leveling agent may be added. . 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 onto a substrate as a coating solution. 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 the coating, the mixture is heated at a relatively low temperature of 90 ° C. to 150 ° C. for 30 minutes to 60 minutes, whereby most of the solvent is scattered, and at the same time, the hydrolyzate or partial hydrolyzate of the alkylsilyl isocyanate forms Act as 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 alkylsilyl isocyanate are cross-linked and strongly bonded.

The thickness of the water-absorbing composite film is 3 after the heat treatment.
If it is less than 3 μm, the antifogging durability tends to be inferior, and if it exceeds 10 μm, optical distortion may occur in appearance quality.

Next, as a raw material of a hydrolyzate or partial hydrolyzate of alkylsilyl isocyanate as a protective film, a general formula R2 _n SiR1 _4-n (where R1 is an alkyl group having 1 or 2 carbon atoms, R2 is an isocyanate group, n
Represents 1 or 2. )) Can be used. The raw material for forming the protective film is added to a solvent such as an ester or a hydrocarbon, and if necessary, a leveling agent is added and mixed to form a coating solution.

Next, these are applied as a coating solution on a glass 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 the coating, the mixture is heated at a relatively low temperature of 90 ° C. to 120 ° C. for 10 minutes to 60 minutes, whereby most of the solvent is scattered and at the same time, the hydrolyzate or partial hydrolyzate of the alkylsilyl isocyanate is cured. It becomes a film. By using a hydrolyzate or partial hydrolyzate of alkylsilyl isocyanate as the protective film, the scratch resistance and the water wiping resistance can be improved.

The thickness of the protective film is preferably 3 to 3 to utilize the water permeability obtained from the three-dimensional structure of the film after the heat treatment.
It is desirable to make it as thin as about 10 nm to a single molecule level, and if it is less than 3 nm, it does not serve as a protective film and has poor abrasion resistance and water wiping resistance. Comes inferior. Note that water permeability is the performance of the protective film, and when water permeability deteriorates, moisture attached to the surface of the film becomes difficult to permeate to the water-absorbing film, accumulates on the surface layer, and dew condensation easily occurs. If the protective film is not used, the antifogging performance cannot be obtained even if a superabsorbent material is used.

As the substrate used in the present invention, glass is typically used, and the glass may be plate glass commonly used for automobiles, architectural and industrial glass, so-called float plate glass, etc. 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 thickness is, for example, about 1.0 mm or more and about 12 mm or less, and about 3.0 mm for architectural use.
The glass is preferably about 10 mm or more and about 10 mm or less, and 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.

[0022]

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 physical properties of the antifogging optical parts having an antifogging film obtained in the present invention and the comparative examples were measured by the following measurement methods.

[Repeated anti-fogging property]: JIS S 4030
(Fogging Stopper Test Method for Glasses) Cloudiness when kept in steam of hot water set at 43 ° C. for 3 minutes, and cloudiness due to exhalation when taken out at room temperature (23 ° C., 63% RH) after holding The condition was observed, and this operation was performed up to 10 cycles, and those having no abnormality in appearance and causing no fogging were judged as acceptable.

[Cooling / anti-fogging property]: After keeping the anti-fogging optical parts in a refrigerator set at 4 ° C. for 30 minutes, they were kept at room temperature (23 ° C.,
(63% RH), the appearance, the degree of fogging, and the fogging due to exhalation were observed. This operation was performed up to 10 cycles, and the appearance was judged as passing without any abnormality.

[Water resistance]: The sample was immersed in distilled water at room temperature (23 ± 2 ° C.) for 6 hours.

[Water-proof wiping resistance]: The surface of the antifogging film is wiped with a cloth squeezed with water and the degree of fogging due to exhalation is observed every 10 times, and no fogging occurs after wiping 50 times. Was passed.

[Traverse abrasion]: A traverse test was carried out using a canvas cloth under a load of 100 g / cm ² , the appearance was observed every 300 times, and the degree of fogging due to exhalation was observed. Those which did not cause fogging were judged as acceptable.

Example 1 ( Preparation of Chemical Solution for Water Absorbent Composite Membrane) 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, An alkylsilyl isocyanate coating agent (trade name “Orgatics SIC-003”, solid content 10%, 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 the polyvinyl acetal resin and the alkylsilyl isocyanate in the water-absorbing composite film after film formation is 97.5.
wt%: 2.5 wt%, a mixed solvent was added and mixed to prepare a chemical solution for a water-absorbing composite membrane.

(Formation of water-absorbing composite film) A glass plate having one side masked is immersed in a dipping tank using this chemical solution as a coating solution and applied by a dipping method of pulling up the glass plate. By heating and drying for about 30 minutes, a film having a thickness of 7.5 μm was formed.

(Formation of Chemical Solution for Protective Film) Ethyl acetate was added to a slippery alkylsilyl isocyanate coating agent (trade name “Orgatic SIC-003”, solid content: 10%, manufactured by Matsumoto Pharmaceutical Co., Ltd.) to give a solid concentration of 1 % To give a chemical solution for a protective film.

(Formation of Protective Film) In a dipping tank using this chemical solution as a coating solution, a moisture-absorptive 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 moisture-permeable film having a thickness of 10 nm was formed.

As shown in Table 1, the glass having an antifogging film obtained by the above method has various antifogging properties, abrasion resistance,
It was confirmed that the glass had an excellent appearance.

[0034]

[Table 1]

Example 2 The procedure of Example 1 was repeated except that the weight ratio of the hydrolyzate or partial hydrolyzate of the polyvinyl acetal resin and the alkylsilyl isocyanate in the water-absorbent composite membrane was adjusted to 99 wt%: 1 wt%. By the same operation, a film having a water-absorbing composite film thickness of 8 μm and a protective film thickness of 10 nm was formed. The evaluation results were as excellent as in Example 1.

Example 3 The procedure of Example 1 was repeated except that the weight ratio of the hydrolyzate or partial hydrolyzate of the polyvinyl acetal resin and the alkylsilyl isocyanate in the water-absorbing composite membrane was 95 wt%: 5 wt%. By the same operation, a film having a water-absorbing composite film thickness of 7 μm and a protective film thickness of 10 nm was formed. The evaluation results were as excellent as in Example 1.

Example 4 A film having a water-absorbing composite film thickness of 7 μm and a protective film thickness of 4 nm was formed in the same manner as in Example 1 except that the thickness of the protective film was adjusted to 4 nm. 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 polyvinyl acetal resin alone was used as the chemical for the water-absorbing composite film. . As a result of the evaluation, in the traverse abrasion, countless scratches were confirmed on the surface after 300 tests. In addition, with respect to water wiping resistance, the film was peeled off by wiping 10 times.

Comparative Example 2 A film having a water-absorbing composite film thickness of 7 μm and a protective film thickness of 2 nm was 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.
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 a protective film was not formed and a single-layer water-absorbing composite film was used.
A μm membrane was obtained. As a result of the evaluation, 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.

[0044]

As described in detail above, according to the present invention,
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 alkylsilyl isocyanate are cross-linked and strongly bonded, and the film thickness is formed on the upper layer of the water-absorbing composite film. 3-10n
m, a monomolecular-level water-permeable protective film is laminated, so it is excellent in antifogging property, water wiping resistance and abrasion resistance, and can maintain antifogging performance for a long period of time. Can be widely used for applications. Furthermore, since an antifogging film can be formed on the surface of a substrate such as glass and plastic at a relatively low temperature, for example, mirror-processed glass,
It has the advantage of being able to easily form a film on the entire or partial surface of automotive glass etc., which has been completed up to bending and molding.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 5/00 C09D 5/00 Z 129/14 129/14 183/04 183/04 F-term (Reference) 4F100 AG00A AH02B AH02C AH06B AH06C AK23B AL05B AT00A BA03 BA07 BA10C CA10B CA10H CC01C EH46 EJ01B GB08 GB32 GB81 JD05C JD15B JK09 JL07 YY00B 4G059 AA01 AC21 FA22 FB06 GA02 GA03 4A06 AB01 A02

Claims (4)

[Claims] 1. A water-absorbing composite membrane comprising a component A comprising a polyvinyl acetal resin shown below and a component B which is a hydrolyzate or partial hydrolyzate of an alkylsilyl isocyanate mixed on the surface of a base material; An anti-fogging base material comprising a protective film having a thickness of 3 to 10 nm and a protective film laminated thereon. A component: polyvinyl acetal resin having a degree of acetalization of 10 mol% or less B component: General formula R2 _n SiR1 _4-n (wherein, R1 is a carbon atom having 1 carbon atom)
Or an alkyl group of 2, R2 is an isocyanate group, and n is 1 or 2, or a hydrolyzate or partial hydrolyzate of an alkylsilyl isocyanate represented by 2. The water-absorbing composite membrane is characterized in that the weight ratio of the polyvinyl acetal resin is 95 to 99 wt%, and the hydrolyzate or partial hydrolyzate of the alkylsilyl isocyanate is 1 to 5 wt%. The antifogging substrate according to claim 1, wherein 3. The protective film has a general formula R2 _n SiR1 _4-n (wherein
R1 represents an alkyl group having 1 or 2 carbon atoms, R2 represents an isocyanate group, and n represents 1 or 2. 2. The antifogging substrate according to claim 1, comprising a hydrolyzate or a partial hydrolyzate of the alkylsilyl isocyanate represented by the formula (1). 4. A process for preparing the antifogging substrate according to claim 1, wherein (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: An alkylsilyl isocyanate represented by R2 _n SiR1 _4-n (wherein R1 is an alkyl group having 1 or 2 carbon atoms, R2 is an isocyanate group, and n is 1 or 2) is added to a liquid containing a solvent. (C) applying the coating liquid on the surface of the base material and heat-treating the coating liquid at a low temperature of 90 ° C. to 150 ° C. to form a water-absorbing composite film. (D) On the upper layer of the water-absorbing composite membrane, a general formula R2 _n SiR1 _4-n (wherein, R1 is an alkyl group having 1 or 2 carbon atoms, R2 is an isocyanate group, and n is 1 or 2) Applying the alkylsilyl isocyanate represented, 90 The method of forming the antifogging base material, which comprises forming a step of forming a protective film was heat-treated at a low temperature of to 120 ° C., an antifogging cured film on the substrate surface by.