JPS6020430B2 - anti-fog coating - Google Patents

Description

[Detailed description of the invention] The present invention relates to a novel anti-fog coating.

In the past, water vapor condensed on the surface of glass, plastic, metal, etc., resulting in water droplets adhering to the surface, which impeded reflectivity and transparency, and caused metal corrosion.
In order to prevent this phenomenon, a number of methods have been proposed in which a film of a water-insoluble hydrophilic polymer is formed on the surface of the substrate.

However, these methods had the following drawbacks. The first point is that when an article with a conventional water-insoluble hydrophilic polymer film attached to its surface is exposed to a high humidity atmosphere (for example, inside a melting room or greenhouse), the polymer film absorbs moisture. , anti-fogging or hair-curdling properties (for a certain period of time)
In this book, cloud-proofing properties and fog-proofing properties are collectively expressed as cloud-proofing properties. ), but if the water absorption amount of the polymer film exceeds the water absorption amount of the bonito powder, water vapor will be exposed in stripes on the polymer film, causing cloudiness. Therefore, conventional hydrophilic polymer films have little effect on applications exposed to high temperature atmospheres. As a method to improve this drawback, a method of adding a nonionic surfactant to a hydrophilic polymer (Samurai Kosho 50-6
No. 437) was also proposed, but since the nonionic surfactant in this hydrophilic polymer gradually washes away during use, it was impossible to maintain excellent anti-ballistic properties over a long period of time. . Another conventional method is to attach a film of a water-insoluble hydrophilic polymer containing acrylic acid as a main component to a substrate, and then immerse the film in an aqueous solution of caustic soda or baking soda (alkaline post-treatment). A method of converting a part of carboxyl groups in a polymer into an alkali salt (Japanese Patent Publication No. 51-1
No. 1124) has also been proposed, but this method not only cannot completely prevent clouding caused by water droplets, but also requires a long time (2 hours) for alkaline post-treatment, making it inefficient in terms of time efficiency. Not only is it bad, but it also requires a large investment in equipment for alkaline post-treatment, making it difficult to industrialize. Due to the current state of the prior art as described above, it has been long awaited for the appearance of an article that has wing protection performance for a long time even in a high temperature atmosphere.

In order to solve this technical problem, the present inventors created a novel anti-fog coating and propose it here.
According to one feature of the present invention, the general formula (wherein X and Y each independently represent a hydrogen atom or a methyl group, and n represents an integer from 1 to 3).

) Water-insoluble hydrophilic copolymers and surfactants whose main components are at least one acrylic ester or methacrylic ester and at least one metal monoacrylate or monomethacrylate. An anti-fog coating is proposed consisting of:

Examples of the hydrophilic single star represented by formula (1) include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, diethylene glycol monoacrylate,
Diethylene glycol monomethacrylate, triethylene glycol monoacrylate, triethylene glycol monomethacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, dipropylene glycol monoacrylate, dipropylene glycol mono/methacrylate, tripropylene glycol monoacrylate Those in which n is an integer of 1 to 3 are preferred, such as tripropylene glycol methacrylate and tripropylene glycol methacrylate.

This is because if n is larger than 3, the strength of the coating will decrease. When producing hydroxymoalkyl noacrylate or hydroxyalkyl monomethacrylate represented by formula (1), a small amount of diacrylate or dimethacrylate is simultaneously produced, but these esters do not need to be removed. . Metal mo/acrylates or monomethacrylates include potassium acrylate, sodium acrylate, aluminum monoacrylate, aluminum monomethacrylate, stearyl calcium acrylate, stearyl calcium methacrylate, stearyl aluminum monoacrylate, stearyl magnesium acrylate, Sorbitsk. Calcium acrylate, Sorbitk calcium methacrylate, Sorbitk magnesium acrylate, Sorbitk magnesium methacrylate, Citric calcium acrylate, Citric lucium methacrylate, Citric magnesium methacrylate, Citric magnesium methacrylate, gluconyl calcium acrylate, gluconyl calcium methacrylate Suitable examples include gluconyl magnesium acrylate, gluconyl magnesium methacrylate, turtric calcium acrylate, tartric calcium methacrylate, salicyl calcium acrylate, salicyl calcium methacrylate, salicyl magnesium acrylate, and salicyl magnesium methacrylate.

The ratio of the hydrophilic monomer and the metal salt in formula (1) is 99:1.
The preferred range is from about 95:5 to about 80:20, although it can vary from 70:3 to 70:3.

If the amount of metal salt is too low, the anti-fog durability will be poor, and if it is too high, the strength of the coating film will be weakened when moisture is absorbed. In addition to the above-mentioned two groups of monomers, small amounts of ethylenically unsaturated carboxylic acids, monoethylenically unsaturated amines, or amides of ethylenically unsaturated carboxylic acids can also be used as comonomers. The use of these comonomers is preferred because it improves the strength and alkali resistance of the coating film. Ethylenically unsaturated carboxylic acids include acrylic acid, itaconic acid, maleic acid,
Cinnamic acid, citraconic acid, etc. can be used.

As the ethylenically unsaturated amine, p-aminostyrene, o-aminostyrene or alkylaminoalkyl acrylates can be used.

As the ethylenically unsaturated carboxylic acid amide, N-isopropylacrylamide, N-isopropylmethacrylamide, diacetone acrylamide, diacetone methacrylamide, N-methylacrylamide, N-methylmethacrylamide, etc. can be used.

The copolymer of the present invention can be produced by a conventional solution polymerization method.

Typical organic solvents include lower alcohols such as methyl alcohol, ethyl alcohol, and inpropyl alcohol, ethylene glycol, propylene glycol,
Glycols and glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol, dipropylene glycol, etc., dimethyl formamide, dimethyl sulfoxide, tetrahydrofurfuryl alcohol, diacetone alcohol, etc. . The copolymerization reaction requires approximately 40 qo
It is generally carried out at temperatures within the range of from to about 120°C.

Conventional means for promoting radical polymerization can be used in conjunction. Therefore, radical polymerization catalysts, ultraviolet irradiation, radiation irradiation, etc. are effective. As radical polymerization catalysts, common free radical initiators such as t-butyl peroctate, isopropyl percarbonate, benzoyl/g-oxide, methyl ethyl ketone peroxide, cumene hydroperoxide, dicumyl peroxide, azobis Isoptilonitrile and the like can be used.

The amount of free radical initiator added is generally about 0.05 to 2% of the monomer, but 0.1 to 2%.
Approximately 0.5% by weight is suitable. If the amount added is too small, polymerization will not occur, and if it is too large, the molecular weight of the resulting polymer will decrease, which is not preferable. Since the anti-fog coating of the present invention is water-proof and has hydrophilic properties, it can be used on glass, plastic, etc.
When attached to the surface of a metal or the like, it absorbs water vapor in the atmosphere and therefore has the effect of preventing water droplets from adhering to the surface of the article, that is, it has cloud-proofing properties.

Moreover, the anti-fog coating of the present invention is different from conventional anti-fog substances in that the water adhering to the surface of the coating after reaching the saturated water absorption amount can completely cover the surface of the coating without forming water droplets. Furthermore, if the amount of water is increased, the water will flow down the surface of the coating, so it can be used for a long time in a high-temperature atmosphere and maintain its vine-proof properties semi-permanently. Therefore, the anti-fog coating of the present invention is useful as an innovative anti-fog coating that exhibits sufficient anti-fog properties even in fields where conventional anti-fog agents are ineffective. Furthermore, when the anti-fog coating of the present invention is compared with the alkali post-treated product described in Japanese Patent Publication No. 51-11124, the coating of the present invention is far superior in terms of both anti-sweep properties and long-lasting anti-fog properties. It is. Furthermore, the coating of the present invention does not deteriorate its coating performance at all by ordinary painting methods, has no inferior adhesion to the substrate than conventional antifogging agents, can improve surface hardness, and can It has the feature that it can be sufficiently cured by a curing method. To form the antifog coating of the present invention, the copolymer is dissolved in a suitable organic solvent and applied to the surface of the article.

As the coating method, commonly used spray coating, dipping, knife coating, roll coping, etc. can be appropriately used. As the organic solvent for dissolving the copolymer, the organic solvent used in the polymerization reaction described above can be used as is, but it can also be diluted with another solvent.

Examples of these solvents include aromatic hydrocarbons such as toluene and xylene, chlorinated hydrocarbons such as dichlorethylene and trichlorethylene, ketones such as methyl ethyl ketone and acetone, esters such as ethyl acetate and butyl acetate, Examples include cyclic ethers such as dioxane and tetrahydrofuran. The anti-ball coating can be cured.

If it is necessary to further increase the strength of the coating film during curing,
Crosslinking agents and catalysts can also be used. As a crosslinking agent, a compound having at least two reactive ethylene bonds,
Polycarboxylic acid compounds, jepoxy compounds, aminoplasts, ammonium dichromate, etc. can be used.
Examples of compounds having at least two reactive ethylenic bonds include ethylene glycol diacrylate, ethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, divinylbenzene, triallyl cyanurate, triallyl isocyanurate, N, N'-methylenebisacrylamide, glycerin triacrylate, diallyl maleate, diallyl monoethylene glycol citrate,
Diaryl itaconate, propylene glycol diacrylate, propylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolmethane triacrylate, trimethylolmethane trimethacrylate, tetramethylolmethane polyacrylate, tetramethane poly Examples include methacrylate and diventaerythritol polyacrylate.

As the polycarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, adipic acid, etc. can be used.

As the jepoxy compound, vinylcyclohexene dioxide, bisphenol A epichlorohydrin, epoxycyclohexylmethyl 3,4'-epoxycyclohexane carpoxylate, etc. can be used.

As the aminoplast, hexamethoxymethylolmelamine, hexabutoxymethylolmelamine, tetramethoxymethylolbenzoguanamine, etc. can be used.

Common free radical catalysts can be used as catalysts, such as t-butyl peroctoate, isopropyl percarbonate, benzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, t-butyl perbesozoate, dicumyl peroxide. , azobisisoputilonitrile, etc. can be used.

Curing is carried out at 70-220°C, preferably 100-200°C.

Furthermore, surprisingly, adding a small amount of surfactant to the coating of the present invention to further improve water wetting also has the effect of significantly increasing surfactant retention.

As the surfactant, anionic surfactants and /ionic surfactants can be used, but polyoxyethylene surfactants are particularly preferred from the viewpoint of long-lasting cloud prevention. As the polyoxyethylene surfactant, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ether, polyethylene glycol alkyl ester, etc. can be used, but polyoxyethylene/nylphenyl ether is particularly preferred.

Next, examples will be shown to explain the present invention in further detail.

In addition, tests for hardness, antifogging properties, and antifogging durability were conducted using the following methods.

Pencil hardness: Measured in an atmosphere with a temperature of 2 pi and a humidity of 40%.

Back resistance test: A sample was placed 5 feet above the surface of 55°C warm water, and the extent of surface continuity was measured immediately after the coating reached saturated water absorption.

The evaluation criteria are as follows.

Rating 5: The surface is very smooth, there are no irregularities caused by water droplets, and the image appears very clear.

4...The surface is slightly uneven, but the image appears clear.

3...The surface has large irregularities, and nearby images appear clear, but distant images appear quite blurry.

2...The unevenness of the surface is quite large, and nearby images appear blurry.

1...The surface is so uneven that it is impossible to see nearby images at all.

Cloud-proofing durability test: A cloud-proofing test was conducted by soaking the sample in 490°C warm water for a certain period of time and then drying it.

Reference Example 1 In a 1.5 flask equipped with a timer, electric heater, and gas inlet, 800 g of ethylene glycol, 180 g of 2-hydroxyethyl methacrylate, 20 g of acrylic acid, and
-butyl peroctate was supplied for 2 hours, and the mixture was heated at 85° C. for 6 hours in a carbon dioxide atmosphere to obtain a polymer solution.

100 g of the solution, 2 g of ethylene glycol dimethacrylate, 0.5 g of t-butyl peroctoate, and 0.02 g of the leveling agent Rayb3 were added and mixed to obtain solution A.

Solution A was applied to a glass plate using a bar coater, dried at room temperature for 30 minutes, and then heated and cured at 160o0 for 1 hour.

The membrane source was 15 Buddhas. The test results are shown in Table 1.

Reference Example 2 To solution A of Reference Example 1, one night of polyoxyethylene nonyl phenyl ether (HLB15) was added.

Reference Example 3 The cloud-proofing treated glass plate obtained in Reference Example 1 was 0.1
It was immersed in N baking soda for 2 hours to perform alkali treatment.

The results are shown in Table 1. Example 1 In a 1.5 flask equipped with a timer, electric heater, and gas inlet, 770 g of ethylene glycol monomethyl ether, 170 g of 2-hydroxyethyl methacrylate, 20 g of acrylic acid, and 25% sodium acrylate were added. Methanol solution) After 40 minutes and t-butyl peroctate were supplied, the mixture was stirred at 90° C. for 6 hours in a carbon dioxide atmosphere to obtain a polymer solution.

Add 100 g of the solution, 2 g of ethylene glycol dimethacrylate, 0.5 g of t-butyl peroctoate, 0.02 g of Misaki Aybo 3 for leveling, and 1 g of polyoxyethylene nonyl phenyl ether, and mix. I got a B.

Solution B was applied to a glass plate using a percoater, dried at room temperature for 30 minutes, and then cured by heating at 16,000 for 1 hour.

The waist thickness was 15r. The test results are shown in Table 1.

Example 2 Citric calcium acrylate was used in place of sodium acrylate in Example 1.

Table 1 As is clear from Table 1, those containing acrylic acid metal salts have extremely good cloud-proofing properties and long-lasting cloud-proofing properties, and also have a good sustained effect of the surfactant.

Claims (1)

[Claims] 1 General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (In the formula, X and Y each independently represent a hydrogen atom or a methyl group, and n is an integer from 1 to 3. A water-insoluble hydrophilic copolymer and an interface mainly composed of at least one acrylic ester or methacrylic ester represented by ) and at least one metal monoacrylate or monomethacrylate. Anti-fog coating consisting of an active agent. 2. The anti-fog coating according to claim 1, wherein the methacrylic acid ester is 2-hydroxyethyl methacrylate. 3. The anti-fog coating according to claim 1 or 2, wherein the metal monoacrylate and/or monomethacrylate is a sodium salt and/or calcium salt. 4. The anti-fog coating according to claim 1, 2 or 3, wherein the surfactant is a polyoxyethylene surfactant.