JPH0826248B2 - Anti-fog coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a coating composition having both excellent antifogging property and abrasion resistance which are excellent in durability.

<Prior Art> Transparent materials such as plastics and inorganic glass are widely used for construction, vehicle or aircraft window glass, greenhouse glass or film, mirrors, spectacle lenses, etc. by utilizing their properties. However, when these transparent materials are used in hot and humid places or interfaces with large temperature and humidity differences, and when they are moved from low to high temperatures by wearing spectacle lenses, Condensation forms on the surface of the article, which causes the inconvenience of clouding the surface and loss of transparency. Further, in the case of a plastic material, there is a drawback that the surface is easily scratched and the transparency is likely to be lowered due to the scratch.

<Problems to be Solved by the Invention> Accordingly, there have been demands from various fields for improvement of these problems, and various attempts to impart antifogging property and scratch resistance have been proposed so far. Among them, as a method for imparting antifogging property, a method of applying a hydrophilic substance such as a surfactant, glycerin, polyalkylene glycol, polyethyleneimine, etc. is proposed for the purpose of making the surface hydrophilic and improving water wettability. Has been done. However, although these methods can temporarily provide antifogging property,
Due to the outflow of the antifogging agent, the antifogging performance deteriorates with time and disappears. Further, the method of applying a hydrophilic polymer such as polyvinyl alcohol or polyhydroxyalkyl (meth) acrylate has a drawback that scratch resistance is not sufficient and scratches are easily formed particularly when moisture is absorbed.

On the other hand, as a method for making the surface of the plastic material hard so as not to be easily scratched, a coating of a melamine or silicone type thermosetting coating or an ultraviolet curing acrylic coating is used. These are effective for increasing the surface hardness of the plastic material, but have no anti-fogging property.

In general, when a component that is rich in hydrophilicity but inferior in abrasion resistance and a component that is rich in abrasion resistance but inferior in hydrophilicity are combined to try to bring out the advantages of both, not only synergistic effect of each physical property but also In many cases, even additivity cannot be obtained sufficiently. That is, when one of the components is added to the other, the physical properties of the receiving component are rapidly deteriorated and the meaning of mixing is often lost.

<Means for Solving Problems> Therefore, as a result of intensive efforts for development to solve the above problems, the present inventors have studied for a long time when applied to the surface of plastic, inorganic glass or the like and cured. The following (A), which can form a coating showing good abrasion resistance and anti-fogging properties,
The present invention has conceived a coating composition comprising (B), (C), (D) and (E) as essential components, each of which is mixed in a predetermined amount.

(A) An organosilicon compound having a non-hydrolyzable organic group having an epoxy group and at least two hydrolyzable groups.

(B) Aliphatic or aromatic polyvalent carboxylic acid or acid anhydride thereof.

(C) Polyethylene glycol having a molecular weight of 2000 to 25000.

(D) An alkyl betaine in which the alkyl group has 12 to 18 carbon atoms.

(E) Curing agent.

<Detailed Description of Means> The component (A) -an organosilicon compound having a non-hydrolyzable organic group having an epoxy group and at least two hydrolyzable organic groups-is generally a silane coupling agent or a carbon functional compound. Is called silane,
Among them, those having an epoxy group as an organic functional group. This component is the main component for forming a coating film of this coating composition, and is highly cross-linked with abrasion resistance due to condensation of hydrolyzed silanol and condensation of epoxy group and (B) component acid or acid anhydride. It gives a high hardness coating with excellent resistance and scratch resistance. Examples of the non-hydrolyzable organic group having an epoxy group of this component include a glycidoxyalkyl group and an epoxycyclohexylalkyl group. Further, examples of the hydrolyzable group include halogen, an acyloxy group, an alkoxy group, an alkoxyalkoxy group, an amino group and the like, but it is not preferable that the free substance after hydrolysis has high reactivity with an epoxy group. , Alkoxy groups or alkoxyalkoxy groups are particularly preferred. Specific examples of these include β-glycidoxyethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, δ-glycidoxybutyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, and γ-glycidyl. Sidoxypropyltriethoxysilane, δ-glycidoxybutyltriethoxysilane, γ-glycidoxypropyltris (methoxyethoxy) silane, β-glycidoxyethyl (methyl) dimethoxysilane, γ-glycidoxypropyl (methyl ) Dimethoxysilane, γ-glycidoxypropyl (vinyl) dimethoxysilane, γ-glycidoxypropyl (methyl) diethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4 -Epoxycyclohexyl) ethyltriethoxysilane, β (3,4-epoxycyclohexyl) ethyl (methyl) diethoxy silane, [2- (3,4-epoxy-4-methylcyclohexyl) propyl] methyldiethoxysilane, and the like, such as.

These compounds may be used alone or in combination of two or more. Further, in order to increase the hardness of the coating film, it is also possible to add silicon functional silane such as methyl silicate, ethyl silicate, butyl silicate, methyltrimethoxysilane, and methyltriethoxysilane as a component.

These organosilicon compounds are hydrolyzed before use. The hydrolysis is carried out at room temperature by adding water in the range of 1/2 to equimolar to the hydrolyzable group, preferably a dilute aqueous solution of hydrochloric acid, sulfuric acid, perchloric acid or the like having a concentration of 0.1 to 0.001N. It is also possible to carry out hydrolysis after mixing the organosilicon compound with the solvent. As the solvent, alcohol, ketone,
Examples thereof include ethers, esters and glycol ethers. Further, depending on the purpose, when the hydrolysis and the initial condensation are carried out in a short time, the hydrolysis reaction can be carried out while heating at 50 to 80 ° C.

The component (B) -aliphatic or aromatic polyvalent carboxylic acid or acid anhydride thereof-reacts with the epoxy group of the component (A) to increase the crosslink density, and has high hardness with excellent wear resistance and scratch resistance. At the same time as providing the above-mentioned coating, the coating also has functions such as antistatic property and dyeability. Furthermore, the component (B) is (D), (E)
It has the function of strengthening the effect of adding components.

The acid anhydrides mentioned as the curing agent for the epoxy resin can all be used as the component (B). In addition, carboxylic acids similar to this (eg, phthalic acid to phthalic anhydride) can also be used. In addition, succinic acid, glutaric acid, which is not often used as a curing agent for epoxy resins,
Adipic acid, malic acid, citric acid, tartaric acid, itaconic acid, citraconic acid, maleic acid, fumaric acid, etc. It is an effective ingredient because it can be used as an optimum blending ratio.

The compounding ratio of the component (B) to the component (A) is 0.1 as an acid anhydride or an acid based on the epoxy group of the component (A).
1 to 1 equivalent. If it is less than 0.1 equivalent, the effect of adding the component (B) is not exhibited, and if it is more than 1 equivalent, a free carboxyl group remains, resulting in poor adhesion and water resistance. Generally, the compounding ratio of the acid anhydride to the epoxy resin is 0.85 to 1.
It is known that the amount is 1 equivalent, but in the present invention, the optimum mixing ratio exists at a lower mixing ratio.

The components (C) and (D) are essential components for imparting antifogging property in the present invention. That is, molecular weight 2000
~ 25,000 polyethylene glycol (hereinafter abbreviated as "PEG") and alkyl betaine having 12 to 18 carbon atoms in the alkyl group are both included as ingredients, resulting in durable and extremely excellent anti-fog performance. Demonstrate.

 When the component (C) is not present and only the component (D) is used, 1) the durability of the coating film deteriorates.

2) In order to bring out the antifogging effect of the same performance, it is necessary to add several times more than in the case of sharing.

3) The durability of anti-fogging performance becomes poor.

The results such as On the other hand, when the component (C) alone is used and the component (D) is not added, some antifogging property is recognized, but the antifogging property under more severe conditions cannot be obtained. That is, it does not become cloudy when it is exhaled at room temperature, but it becomes cloudy when it is exposed to boiling steam or when it is moved from an atmosphere of -20 ° C to room temperature. According to the present invention, it is possible to form a coating film which does not fog even under such conditions.

The component (C) and PEG having a molecular weight of 2000 to 25,000 are added in an amount of 5 to 50 parts by weight based on 100 parts by weight of the hydrolysis-condensation product of the component (A). When the molecular weight is less than this range or the addition amount is small, the antifogging property is not sufficiently exhibited. Molecular weight 25,000
When it is larger than the above range, the composition is difficult to obtain and the viscosity of the present composition is high, which makes the coating operation difficult. (C) component is 50
If the amount is more than the amount by weight, the adhesion of the coating film to the substrate becomes poor. It is also possible to improve the performance (hardness etc.) of the coating film by reacting with a part of the component (B) and esterifying it to form carboxyl groups at both ends prior to addition. is there.

The component (D), an alkyl betaine having an alkyl group having 12 to 18 carbon atoms, is a particularly essential component in the present invention. Although this component is a kind of surfactant, other surfactants, that is, other kinds of anion, cation and nonion type cannot obtain the antifogging performance as in the present invention. Similarly, the amphoteric type alkylglycine cannot obtain the performance of the present invention. In addition, even if a silicone-polyoxyethylene block / graft copolymer that is clearly shown to have antifogging performance is used, the antifogging performance as in the present invention cannot be obtained.

The E component-hardening agent-in the present invention is E-1) dicyandiamide, E-2) aluminum trialkoxide or an aluminum chelate compound in which these alkoxides are substituted with β-diketone or β-ketoester E-3) imidazole or its 1 It is a compound selected from the group consisting of substituted isidazoles in which all or part of the 2, 4, 5 positions are substituted with an alkyl group, an aryl group, a hydroxyalkyl group, an alkoxyalkyl group, a cyanoalkyl group or the like. Specific examples of the aluminum alkoxide or aluminum chelate compound of E-2 include aluminum isopropoxide, aluminum isobutoxide, aluminum-Sec butoxide, aluminum bis (isopropoxide) methylacetoacetate, aluminum bis (Sec-butoxide) ethyl. Acetoacetate, aluminum bis (ethylacetoacetate) acetylacetonate, aluminum ethylacetoacetate bis (acetylacetonate) aluminum acetylacetonate and the like. Further, specific examples of the substituted imidazole of E-3 include 2-methylimidazole 2-ethylimidazole 2-ethyl-4-methylimidazole 2-isopropylimidazole 2-phenylimidazole 1-benzyl-2-methylimidazole 1-dia. Noethylimidazole 1-cyanoethyl-4-methylimidazole 2-phenyl-4-methyl-5-hydroxymethylimidazole 1-cyanoethyl-2-phenyl-4,5-bis (cyanoethoxymethyl) imidazole and the like.

Two or more of these compounds may be mixed and used as long as they are in the same group. The optimum amount of these components to be added varies depending on each component, but is generally 0.5 to 5 parts by weight with respect to 100 parts by weight of the hydrolysis-condensation product of the component (A).

In addition to the above-mentioned essential components, the composition of the present invention may contain a solvent, an additive, etc. in order to improve the performance as a coating material.

As the solvent, alcohol, ketone, ester, ether, glycol ether, cyclic ether or the like can be used as appropriate. As the additive, a silicone-based surfactant, a fluorine-based surfactant or the like can be used for the purpose of improving the smoothness of the surface. Further, it is possible to add an ultraviolet absorber to block ultraviolet rays and prevent deterioration of the substrate-coating film interface due to ultraviolet rays. It is also possible to add a dye or pigment to the composition of the present invention within a range that does not impair the transparency to color the cured film formed from the composition.

The antifogging coating composition of the present invention can be applied to various substrates and is used by applying it to a substrate and heating it to form a cured film. In this case, the base material is not particularly limited as long as it does not impair the characteristics of the present invention, but as the base material that can generally exhibit its characteristics effectively, plastic, inorganic glass, transparent ceramic, metal, etc. is there. Further, from the practical examples, the present invention is preferably used for various plastic and inorganic glass lenses, goggles, window glass, greenhouse glass and film, and cover glass for various instruments.

As a method for applying the composition of the present invention to a substrate, for example, a commonly known method such as brush coating, spray coating, dipping method, spin coating or flow coating can be used. It is also possible to pretreat the substrate in advance by various kinds of primer treatment, active gas treatment, corona treatment, or chemical treatment such as acid or base for the purpose of improving the adhesion to the substrate.

<Effects of the Invention> As will be apparent from the examples and comparative examples described below, the coating composition of the present invention is obtained by coating and curing a coating showing good abrasion resistance and antifogging property over a long time on a plastic inorganic glass. Can be obtained.

<Example> Hereinafter, the present invention will be described in more detail with reference to examples. In describing the examples, the test method for the cured coating is shown below.

(1) Appearance The transparency, coloring, and surface condition were examined by visual observation.

(2) Adhesion Adhesive tape (product name "Cellotape" manufactured by Nichiban Co., Ltd.) is strongly adhered to the coating surface of the test piece by making 100 pieces of burdock that reach the base material of 1 mm square from the top of the coating film with a knife. It was attached and quickly peeled off in the perpendicular direction, and the presence or absence of peeling of the coating film was indicated by the quality.

(3) Surface hardness According to JIS K-5400, pencil scratch hardness tester (load 1
kg) and showed the highest pencil hardness without scratches.

(4) Scratch resistance The surface was rubbed with # 0000 steel wool and judged as follows.

A: Almost no scratches.

B: A little scratched.

C: Severely scratched.

(5) Anti-fogging property in an atmosphere of 25 ° C, 60 to 65% RH (hereinafter referred to as room temperature)
Judgment is made based on the state of cloudiness when the exhaled air is blown on the test piece placed for 3 seconds.

◯: No fog occurs at all.

Δ: Fogging occurs, but disappears within 5 seconds.

X: It takes more than 5 seconds for the haze to disappear.

Boiled steam is applied to the coating film test piece kept at room temperature for 5 seconds, and it is judged by the cloudiness.

◯: No fog occurs at all.

Δ: Water droplets are attached, but the particles are large and the transparency is not lost.

X: Fogging occurs due to adhesion of minute water droplets.

After leaving it at -20 ℃ for 30 minutes, remove it at room temperature and judge by the cloudiness.

◯: No fog occurs, or a fog disappears as a liquid film within 30 seconds.

Δ: The cloudiness disappears within 2 minutes.

×: The cloudiness does not disappear even if it exceeds 2 minutes.

(6) Durability of anti-fogging property The coating film test piece is immersed in warm water at 80 ° C for 30 minutes, and then the anti-fogging property test is performed.

Examples 1 to 20, Comparative Examples 1 to 5 (1) Preparation of coating composition 141 g of γ-glycidoxypropyltrimethoxysilane (trade name: A-187, Nippon Unicar Co., Ltd.) was placed in a beaker and stirred. While adding 30 g of 0.01 N dilute aqueous hydrochloric acid solution. After stirring for 30 minutes, leave at room temperature for 24 hours. In this It contains 100 g of the hydrolyzed condensate converted as. To this, the amount of maleic anhydride (reagent 1
Grade), PEG6000 (trade name: PEG6000P, average molecular weight: 7800 to 900)
0, Sanyo Chemical Industry Co., Ltd. was added, 150 g of ethylene glycol monoethyl ether was added as a solvent, and the mixture was stirred and uniformly dissolved. To this, an amount of alkyl betaine (trade name: Anon BF, NOF Corporation) shown in Table 1 was further added. Since this is an aqueous solution, the amount as alkylbetaine is shown. Further, a curing agent described in Table 1,
As a leveling agent, 0.2 g of L-77 (a silicone-based surfactant manufactured by Nippon Unicar Co., Ltd.) was added to obtain a coating composition.

As comparative examples, those not containing succinic anhydride as the component (B) (Comparative Example 1), too much (Comparative Example 2), and those not containing PEG as the (C) component as compared to the Examples ( Comparative example 3), too little (comparative example 4) and too much (comparative example 5) are shown.

(2) Painting and curing A lens made of poly (diethylene glycol bisallyl carbonate) (hereinafter referred to as CR-39 lens) at 50 ° C.
After immersing in 10% caustic soda aqueous solution heated for 3 minutes,
It was thoroughly rinsed with water to completely remove the water, then dipped in the above coating composition, applied at a pulling rate of 10 cm / min, and heat-cured in a hot air dryer at 120 ° C. for 3 hours. The results of the characteristic test are shown in Table 2.

From the results shown in Table 2, Comparative Example 1 which does not contain the component (B) has a problem in abrasion resistance and scratch resistance, and Comparative Example 2 in which the component (B) is too much causes a problem in adhesion. , Comparative Examples 3 and 4 which do not contain component (C) or are too small, may cause problems in antifogging property, and Comparative Example 5 which contains too much (C) component may cause problems in surface hardness and scratch resistance. Recognize.

Examples 21 to 30 (1) Preparation of coating composition 141 g of γ-glycidoxypropyltrimethoxysilane was placed in a beaker and stirred, and 0.01N dilute aqueous hydrochloric acid solution was added.
After adding 30 g and stirring for 30 minutes, the mixture was left at room temperature for 24 hours. In this It contains 100 g of the hydrolyzed condensate converted as. In addition to these, the acids or acid anhydrides shown in Table 3 (all of which are reagent grade 1 or equivalent) and polyethylene glycol 20000
(Average molecular weight 18,000 to 25,000, NOF Corporation) 13g was added, and methyl ethyl ketone 50g and methanol 80g as solvent.
And stir. Lauryl betaine (trade name:
Bister ML, Matsumoto Yushi Co., Ltd.) was added as a solid substance to 10 g, and 2-ethyl-4-methylimidazole 2 g as a curing agent and L-77 0.2 g as a leveling agent were added to the composition for coating. And

(2) Coating and curing The CR-39 lens was treated and coated by the same method as in Example 1, and then heat-cured in a hot air dryer at 110 ° C for 2 hours. The results of the characteristic tests are shown in Table 3.

Examples 31 to 35, Comparative Examples 6 to 12 (1) Preparation of coating composition 141 g of γ-glycidoxypropyltrimethoxysilane was placed in a beaker and stirred while stirring to obtain a 0.01N dilute hydrochloric acid aqueous solution.
After adding 30 g and stirring for 30 minutes, the mixture was left at room temperature for 24 hours. In this It contains 100 g of the hydrolyzed condensate calculated as. 25 g of trimellitic anhydride and 15 g of PEG having various molecular weights shown in Table 4 are added thereto, 50 g of ethylene glycol monoethyl ether and 80 g of methanol are added as a solvent, and the mixture is stirred and dissolved.

To this, 10 g of lauryl betaine was added, and further 3 g of aluminum acetylacetonate was added as a curing agent to obtain a coating composition.

As a comparative example, PEG having a small molecular weight (Comparative Example 6,
7), those having an excessively large molecular weight (Comparative Example 8), and those using other surfactants in place of lauryl betaine (Comparative Examples 9 to 12) were prepared.

(2) Coating and curing The CR-39 lens was treated, coated and heat cured in exactly the same manner as in Example 2. The results of the characteristic tests are shown in Table 4.
The composition of Comparative Example-8 had a very high viscosity, and a smooth coating film could not be obtained.

From the results shown in Table 4, Comparative Examples 6 and 7 in which the molecular weight of PEG as the component (C) is too small, and Comparative Examples 9 to 12 in which a surfactant other than alkyl betaine was used as the component (D) were all antifogging. It turns out that it causes a problem in sex.

Examples 36 to 40 (1) Preparation of coating composition 141 g of γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyl (methyl) diethoxysilane
Take 50g and 40g of Methyl Ethyl Ketone into a 500ml three-necked fusco and attach a reflux condenser, a dropping funnel and a thermometer.
Heat to 80 ° C. on a water bath to reflux. With a dropping funnel
35 g of 0.01 N dilute hydrochloric acid aqueous solution is added dropwise over 30 minutes to carry out hydrolysis. After completion of dropping, reflux is continued for 2 hours to carry out precondensation. To this, trimellitic anhydride 35g, PEG20000
Add 20 g and 160 g of methanol as a solvent and stir. Furthermore, 12 g of lauryl betaine was added, 2-methylimidazole 3 g as a curing agent, and L-7 as a flow control agent.
7 0.2 g was added to obtain a coating composition.

(2) Coating and curing Treat each sample shown in Table 5 with a 10% caustic soda aqueous solution heated to 50 ° C, rinse thoroughly with water, wipe off water, and then dip at a pulling rate of 15 cm / min. Application, fifth
It was heat-cured under the conditions shown in the table.

Examples 41, 42 (1) Preparation of coating composition 246 g of (3,4-epoxycyclohexyl) ethyltrimethoxysilane is placed in a beaker, and while stirring, 58 g of a 0.01 N aqueous solution of perchloric acid is added and hydrolyzed. After stirring for 1 hour, leave at room temperature for 24 hours. PEG20000 30g
Take in a beaker and heat on an electric heater to 130 ° C to 140 ° C to dissolve. To this, 2 g of trimellitic anhydride is added and stirred at this temperature for 1 hour. After mixing both components, 80 g of methylnadic acid anhydride is added, 200 g of methanol and 50 g of 1,4-dioxane are added as solvents, and the mixture is stirred. 16g of stearyl betaine (trade name; Bister MS, manufactured by Matsumoto Yushi Co., Ltd.)
In addition, 4.5 g of 2-ethyl-4-methylimidazole as a curing agent, L-77 as a flow control agent.
Add 5 g to make a coating composition.

(2) Coating and curing CR-39 lens treated with an aqueous solution of caustic soda (Example-
41) and a polycarbonate molded product lens (Mitsubishi Gas Chemical Co., Inc., Iupilon S-3000) (Example-42) were applied by a dipping method at a pulling speed of 15 cm / min, and then in a hot air dryer at 120 ° C. for 2 hours. Heat cured. The results of the characteristic tests are shown in Table 6.

Claims (1)

[Claims] 1. The following components (B), (C), (D) and (E) are added in respective amounts to 100 parts by weight of the hydrolyzed condensate of the following component (A). An antifogging coating composition characterized by the above. (A) An organosilicon compound in which a non-hydrolyzable organic group having an epoxy group and at least two hydrolyzable groups are introduced. (B) Aliphatic or aromatic polycarboxylic acid, or its acid anhydride: 0.1 to 1 equivalent as an acid with respect to the epoxy group contained in the component (A). (C) Polyethylene glycol having a molecular weight of 2000 to 25,000 ...
5 to 50 parts by weight. (D) Alkyl group Alkyl betaine having 12 to 18 carbon atoms ... 4
~ 40 parts by weight. (E) Curing agent: 0.5 to 5 parts by weight.