JP5151062B2 - Coating liquid for imparting hydrophilicity to coating film and method for producing anti-fogging coating film - Google Patents

Description

  The present invention relates to a coating solution for imparting hydrophilicity to a coating to improve the anti-fogging property of the coating, and an anti-fogging coating formed using the coating solution.

  The haze generated on the substrate surface of glass and other articles is caused by a dew condensation phenomenon in which countless minute water droplets are formed on the substrate surface. In order to prevent this fogging, a hydrophilic coating that forms an infinite number of minute water droplets generated on the surface of the substrate as a uniform water film, a water-absorbing coating that takes water droplets into the coating, and the like have been formed on the substrate.

For example, Patent Document 1 discloses that the hydrophilicity of the glass surface is improved by applying a surfactant having excellent hydrophilicity on a substrate. In Patent Documents 2 and 3, a coating having a fine uneven shape is formed on a substrate so that retention of the applied hydrophilic chemical species can be prolonged, and a surfactant or the like is formed on the uneven portion. A hydrophilic member in which a chemical species having excellent hydrophilicity is retained is disclosed.
Japanese Patent Publication No. 52-47926 Japanese Patent Laid-Open No. 11-100284 JP 2000-2651653 A

  Conventionally, including Patent Documents 1 to 3 and the like, it has been proposed to improve the antifogging property of an article by holding a surfactant having excellent hydrophilicity on the outermost surface of the article. However, since the retention time of these chemical species on the surface is short, it has been a problem that the time that can be eluted from the surface immediately and exhibit antifogging properties is short. Therefore, in order to solve this problem, an object of the present invention is to provide means for producing an effect in prolonging the retention of the chemical species.

  In order to solve the above-mentioned problems, the present invention makes it possible to prolong the time during which antifogging properties can be exhibited by examining the coating for retaining a surfactant having excellent hydrophilicity and the chemical species retained in the coating. The idea was made after intensive study.

  That is, the coating liquid of the present invention is a coating liquid for imparting hydrophilicity to a film made of a water-absorbing urethane resin formed on a substrate, the coating liquid comprising a surfactant, an organic isocyanate, A surfactant having a hydroxyketone is mixed, and the surfactant is characterized in that a surfactant having at least an isocyanate-reactive group is used.

When the coating solution is applied to the coating, the coating solution is absorbed into the coating. Then, a surface active agent having an organic isocyanate and isocyanate-reactive groups are reacted in the liquid absorbing state. As a result, since the reaction product formed by combining two chemical species becomes a larger chemical species, the reaction product dispersed in the film is easily retained between the resin crosslinks, and exhibits antifogging properties. Succeeded in prolonging the period that can be done.

  In addition, the hydrophilic property as used in the field of this invention refers to the case where the contact angle of the water droplet to a film is 20 degrees or less. By making the contact angle 20 ° or less, it becomes easy to develop antifogging properties due to hydrophilicity.

  In addition, the solvent used in the coating solution of the present invention is soluble in each chemical species, has an affinity for the coating, and needs to be absorbed in the coating. In the present invention, it was possible to find a solvent having hydroxy ketones as being suitable for this condition. The solvent is an important component in the coating solution in order to impart hydrophilicity to a film made of a urethane resin having a water absorption of 10 to 40% by weight formed on the substrate.

  The surfactant having an isocyanate-reactive group is preferably a cationic surfactant. This is because the surfactant is a component that is highly effective in imparting hydrophilicity to the film.

  In addition to the surfactant having an isocyanate-reactive group, a surfactant that does not have an isocyanate-reactive group is preferably used as the surfactant in the coating solution. As the surfactant, a cationic, anionic, nonionic or amphoteric one can be used.

These species are easily eluted from the film than the species in which the surfactant having an organic isocyanate and an isocyanate-reactive group is generated by the reaction, but because it is applied easily ingredient the film with hydrophilicity, the present invention It may be introduced into the coating solution.

  When the coating liquid of the present invention is applied to a film made of a urethane resin having water absorption formed on a substrate, it can impart hydrophilicity to the film. And since the holding | maintenance in the film of the chemical species which provides hydrophilic property is stable, a film comes to exhibit hydrophilic property for a long term, and provides the anti-fogging article | item which was more excellent in anti-fog property. To be effective. In addition, since the coating solution has good affinity with the coating film, it is easy to apply the coating solution to the coating film, and even if the anti-fogging article is used for a long time and the hydrophilicity is lowered, again, It is also easy to improve or restore the hydrophilicity of the article.

  In the present invention, by applying a coating liquid for imparting hydrophilicity to a film made of a water-absorbing urethane resin formed on a base material, hydrophilicity is imparted to the film, an antifogging film, And an antifogging film-forming substrate is formed. The coating solution is a mixture of a surfactant and a solvent having organic isocyanate and hydroxyketone, and the surfactant contains at least a surfactant having an isocyanate-reactive group.

  The coating liquid for imparting hydrophilicity to the coating is a solvent having a hydroxyketone, an organic polyisocyanate, a surfactant having an isocyanate-reactive group, preferably a surfactant having no isocyanate-reactive group, More preferably, it can be prepared by mixing an organotin compound as a curing catalyst.

As hydroxy ketones, acetone alcohol, acetoin, diacetone alcohol, benzoin and the like are preferable. As the organic polyisocyanate, for example, hexaethylene diisocyanate, full E two diisocyanate, 2,4- or 2,6-tolylene diisocyanate, diphenyl E Nirumetan 4,4-diisocyanate, 3,3-dimethyl-4,4 Biff E d diisocyanate, dicyclohexylmethane-4,4-diisocyanate, isophorone diisocyanate, omega, .omega.-diisocyanate-1,3-dimethylbenzene, omega, omega-1,4-dimethylbenzene, omega, .omega.-diisocyanate-1,3 -Dimethylcyclohexane, ω, ω-diisocyanate-1,4-dimethylcyclohexane and mixtures thereof are preferred.

  As the surfactant having an isocyanate reactive group, anionic, cationic, zwitterionic and nonionic surfactants can be used. Anionic compounds include castor oil monosulfate, castor oil monophosphate, sorbitan fatty acid ester sulfate, sorbitan fatty acid ester phosphate, sorbitol fatty acid ester sulfate, sorbitol fatty acid ester phosphate, sucrose fatty acid ester sulfate, sucrose fatty acid ester phosphate, polyoxy Examples include alkylene castor oil ether monosulfate, polyoxyalkylene castor oil ether monophosphate, polyoxyalkylene sorbitan fatty acid ester sulfate, polyoxyalkylene sorbitan fatty acid ester phosphate, polyoxyalkylene glycerin ether monosulfate, polyoxyalkylene glycerin ether monophosphate, and the like.

  As cationic compounds, dialkanolamine salts, trialkanolamine salts, polyoxyalkylene alkylamine ether salts, fatty acid trialkanolamine ester salts, polyoxyalkylene dialkanolamine ether salts, polyoxyalkylene trialkanolamine ether salts , Di (polyoxyalkylene) alkylbenzylalkylammonium salt, alkylcarbamoylmethyldi (polyoxyalkylene) ammonium salt, polyoxyalkylenealkylammonium salt, polyoxyalkylenedialkylammonium salt, ricinoleamidopropylethyldimonium ethosulphate, etc. Is mentioned.

  Examples of zwitterionic compounds include N, N-di (β-hydroxyalkyl) N-hydroxyethyl-N-carboxyalkylammonium betaine, N-β-hydroxyalkyl-N, N-dipolyoxyalkylene-N-carboxy. Alkylammonium betaines, monoesters of N-alkyl-N, N-di (polyoxyalkylene) amines and dicarboxylic acids, N- (polyoxyethylene) -N ', N'-di (polyoxyethylene) aminoalkyl-N -Alkyl-N-sulfoalkylammonium betaines, N, N-di (polyoxyethylene) -N-alkyl-N-sulfoalkylammonium betaines, N- (β-hydroxyalkylaminoethyl) -N- (β-hydroxyalkyl) Aminoethyl carboxylic acid, N, N'-bis (2-hydroxyalkyl) -N, N'-bis (carboxyethyl) ethylenediamine salts, N-(beta-hydroxyalkyl) -N ', N'-di (polyoxyethylene) -N- carboxyethyl ethylenediamine salts.

Nonionic types include polyoxyethylene polyoxypropylene block polymer, sorbitol fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, fatty acid monoglyceride, polyoxyalkylene fatty acid monoglyceride, polyglycerin fatty acid ester , Polyoxyalkylene castor oil ether, polyoxyalkylene alkylamine , polyoxyalkylene alkylamide and the like.

  As the surfactant having no isocyanate-reactive group, cationic, anionic, nonionic and zwitterionic ones can be used. Examples of the anionic compounds include polyoxyethylene alkyl ether sulfates, alkyl sulfates, alkylbenzene sulfonates, α-sulfo fatty acid esters, α-olefin sulfonates, alkane sulfonates, and the like.

  Examples of the cationic compounds include alkyl trimethyl ammonium salts, dialkyl dimethyl ammonium salts, alkyl dimethyl benzyl ammonium salts, and amine salts.

  Furthermore, examples of the nonionic type include sorbitan fatty acid ester and polyoxyethylene sorbitan fatty acid ester. Examples of the zwitterionic type include alkylcarboxybetaine, alkylamino fatty acid sodium, alkylbetaine, and alkylamine oxide. Is mentioned.

  The organotin compounds that are curing catalysts include dibutyltin dilaurate, dioctyltin dilaurate, stannous octoate, dibutyltin dioctoate, dibutyltin diacetate, dibutyltin marker butylide, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin It is preferable to use marker butylide, dioctyl tin thiocarboxylate or the like.

  The coating method of the coating liquid of the present invention on the water-absorbing film includes roll coating method, dip coating method, brush coating method, spray coating method, bar coating method, knife coating method, die coating method, spin coating method, curtain coating method, hand It can be performed by a known method such as painting. It is applied to a substrate and is naturally dried at room temperature for about 24 hours, or heated at 80 ° C. to 140 ° C. for 10 minutes to 60 minutes to dry the solvent in the coating solution to form a film and impart hydrophilicity.

  The coating film to which the coating liquid of the present invention is applied is formed on the substrate. As the substrate, it is preferable to use a window that transmits light in the visible light region or a mirror that reflects light in the visible light region. And soda lime silicate glass is used suitably as a typical member used for these windows, mirrors, and the like. The glass is a glass usually used for automobiles, buildings, industrial glasses and the like, and can be produced by a float method, a duplex method, a roll-out method or the like.

  As glass types, it can be used for various colored glasses such as clear, green and bronze, various functional glasses such as UV, IR cut glass and electromagnetic shielding glass, netted glass, low expansion glass, zero expansion glass and fireproof glass. Various glass products such as glass, tempered glass or similar glass, laminated glass, multilayer glass, mirrors produced by the silvering method or vacuum film forming method, flat plates, bent plates and the like can be used. The plate thickness is not particularly limited, but is preferably 1.0 mm or more and 10 mm or less, and is preferably 1.0 mm or more and 5.0 mm or less for vehicles.

  In addition to glass, resin films such as polyethylene terephthalate, resins such as polycarbonate, metals (particularly metal mirrors), ceramics, and the like can be used for the base material.

  The coating agent obtained by mixing a chemical species having an isocyanate group on the outermost surface of the substrate and a polyol is applied to the substrate, and the coating agent is heated by heating at 80 to 140 ° C. for 10 to 60 minutes. It hardens | cures and forms the film which consists of urethane resin which has water absorption. The coating method can be performed by a known method such as a roll coating method, a dip coating method, a brush coating method, a spray coating method, a bar coating method, a knife coating method, a die coating method, a spin coating method, a curtain coating method, or a hand coating method. it can. After coating, the solvent in the coating solution is dried by heating at 80 ° C. to 140 ° C. for 10 minutes to 60 minutes to form a film. In addition to the chemical species, the coating agent may have a solvent having a hydroxyketone as described above and a tin-based curing catalyst as described above.

  For the polyol, an oligomer of the water-absorbing polyol is preferably used in order to cause the film to exhibit antifogging properties due to water absorption. The water-absorbing polyol is a chemical species that brings water absorption to the film after the film is formed, and is a polyol having an alkylene oxide chain such as polyethylene glycol or a polyol having a main chain of a copolymer of ethylene oxide / propylene oxide, that is, oxyalkylene. Polyols of the system are typically used. The alkylene oxide chain is a chemical species that can take in water by hydrogen bonding, that is, can be taken into the film as bonded water, and has an advantage that water can be easily absorbed without swelling the film. Of the alkylene oxides, the smaller the molecular weight of the alkylene unit, the more advantageous for water absorption. Therefore, the alkylene oxide chain used is preferably an ethylene oxide chain, a propylene oxide chain, particularly an ethylene oxide chain. .

  The oxyalkylene polyol preferably has a number average molecular weight of 400 to 5,000. This is because when the number average molecular weight is less than 400, the ability to absorb water as bound water becomes low, and when the number average molecular weight exceeds 5000, the strength of the coating tends to decrease. Considering the water absorption and film strength of the coating, the average molecular weight is preferably 400-4500. And in the case of especially preferable polyethylene glycol, it is preferable to use a thing with a number average molecular weight of 400-2000.

  The water-absorbing polyol described above is combined with a polyester polyol such as a polycarbonate polyol having a number average molecular weight of 500 to 2000, a polycaprolactone polyol, an average molecular weight 2000 to 4000 acrylic polyol, a short chain polyol having a number average molecular weight of 60 to 200, and the like.

The short-chain polyols described above, et Ji glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, glycerin , 2-ethyl-2- (hydroxymethyl) -1,3-propanediol, 1,2,6-hexanetriol, alkyl polyols such as 2,2′-thiodiethanol, alkanolamines such as diethanolamine and triethanolamine, etc. Can be used . The species having isocyanate groups used to form the target membrane, diisocyanates, preferably hexamethylene diisocyanate be used trifunctional polyisocyanate having the biuret and / or isocyanurate structure as the starting material preferable. The substance has weather resistance, chemical resistance and heat resistance, and is particularly effective for weather resistance. In addition to the above substances, diisophorone diisocyanate, diphenylmethane diisocyanate, bis (methylcyclohexyl) diisocyanate, toluene diisocyanate and the like can also be used.

  And in the film obtained, it is preferable to adjust the chemical species for forming the film and the amount thereof so that the water absorption of the film made of water-absorbing urethane resin is 10 wt% to 40 wt%. When the water absorption rate of the coating is less than 10% by weight, the amount of liquid supplied into the coating of the coating agent of the present invention is small, and it tends to be difficult to impart hydrophilicity to the coating. This is because the strength tends to decrease.

  In addition, a surfactant having an isocyanate-reactive group used in the coating agent of the present invention is added to the coating agent for forming the coating when forming the coating, and the coating agent of the present invention is formed after the coating is formed. May be applied to the film to improve the hydrophilicity of the film.

Example 1
1. Preparation of coating film made of urethane resin having water absorption A coating solution for forming a water absorbing film made of a polymer material on the outermost surface of the substrate was prepared by the following procedure. The average polycaprolactone diol (trade name "PLACCEL L212AL" Daicel Chemical Industries) having a molecular weight of 1250 0.95 g quantity, and a primary ethylene glycol 0.47g amounts reagent, polyethylene glycol having an average molecular weight of 1000 to bring the water-absorbent resin 3 . 32 g amount was mixed.

4.26 g of hexamethylene diisocyanate burette-type polyisocyanate (manufactured by Sumitomo Bayer Urethane, trade name “N3200”) is added to and mixed with the mixture obtained above, and diacetone alcohol is added so that the total components are 30% by weight. in diluted, to prepare a coating solution to obtain a coating film made of a urethane resin having a water absorption. The coating solution was applied by spin coating to the entire surface of the mirror substrate (100 mm × 100 mm × 5 mm (thickness) size) obtained by silvering a soda lime glass plate on the side opposite to the reflective layer.
Thereafter, a film made of a urethane resin having water absorption was formed on the substrate by heating at 150 ° C. for 60 minutes. The water absorption of the coating was 20% by weight . The water absorption is measured by the following procedure. The weight of the glass before coating (A), the weight of the sample measured with a precision balance (B) immediately after coating and heating to the glass, and water vapor at 40 ° C. applied to the coating, resulting in cloudiness and distortion in the field of view. It was derived from the following formula from the weight (C) of the sample at the time.

Water absorption rate = (C−B) / (B−A) × 100 [ wt %]

2. Preparation of coating solution for imparting hydrophilicity to coating film and application of coating solution to coating film Lisinoleamidopropylethyldimonium ethosulphate (Lipo Chemicals), a cationic surfactant having an isocyanate-reactive group Inc., trade name “Lipoquant-R” ) An amount of 56 g was mixed with an amount of 1.56 g of an ionic surfactant having no isocyanate-reactive group (manufactured by Toho Chemical Co., Ltd., sodium polyoxyethylene lauryl ether sulfate, trade name “ALSCOPE NS-230”). .

Obtained above mixture of hexamethylene diisocyanate biuret type polyisocyanate (Sumitomo Bayer Urethane Co., trade name "N3200") 0.48 g quantity added and mixed, as described above all components is 18.3 by weight% Dilution with diacetone alcohol produced a coating solution for imparting hydrophilicity to the coating.

  The coating solution obtained in 1 above is wiped with a cotton cloth soaked with the coating solution, and the coating solution is applied to the coating, and then left to stand for 24 hours. To give an antifogging film.

Example 2
3.12 g amount of ricinoleamidopropylethyldimonium ethosulphate (trade name “Lipoquant-R”, manufactured by Lipo Chemicals Inc.), a cationic surfactant having an isocyanate-reactive group, and hexamethylene diisocyanate biuret type polyisocyanate (Sumitomo Bayer urethane Co., trade name "N3200") were mixed 0.48g addition amount, diluted with diacetone alcohol so that the entire component is 18.3 by weight%, hydrophilic the film A coating solution for imparting properties was prepared.

And by wiping the film made of urethane resin having water absorption obtained in Example 1 with the cotton cloth soaked with the coating liquid, the coating liquid is applied to the film, and then allowed to stand for 24 hours. Further, hydrophilicity was imparted to the water-absorbing film to obtain an antifogging film.
[Characteristic evaluation of Examples 1 and 2]
By evaluating the following items, the characteristics of the antifogging coatings of Examples 1 and 2 were evaluated.
○ Evaluation item 1: Visual evaluation of the image reflected in the mirror when exhaled air is applied to the coating ○ Evaluation item 2: Water vapor hits the anti-fogging coating on the sample at a position 3 cm from the surface of the thermostat set at a water temperature of 43 ° C. Then, after standing still for 3 minutes, the image reflected on the mirror when it is quickly moved to room temperature of about 25 ° C. is visually evaluated. This is defined as one cycle, repeated evaluation is performed, and the number of cycles required for the occurrence of distortion in the field of view is counted.
Evaluation item 3; Table 1 shows the evaluation results for the contact angle of water droplets (JIS R 3257).
For comparison, the tests of evaluation items 1 to 3 were also performed when the coating solution obtained in 1 above and the coating solution obtained in 2 above were applied to a mirror base material. The former is referred to as Comparative Example 1, and the latter is referred to as Comparative Example 2.

Claims (4)

Was made form on a substrate, a coating liquid for providing the film with hydrophilicity consisting urethane resin water absorption has a 10 to 40% by weight of water-absorbent, the coating solution of the surfactant and organic It is obtained by mixing a solvent having an isocyanate and a hydroxyketone, and a surfactant having at least an isocyanate-reactive group is used as the surfactant. Coating liquid for. The coating liquid according to claim 1, wherein a surfactant that does not have an isocyanate-reactive group is further used as the surfactant. A method for forming an antifogging film comprising a step of forming a film made of the urethane resin on a base material and a step of applying a coating liquid that imparts hydrophilicity to the film, wherein the coating liquid comprises: A method for producing an antifogging film, comprising the coating liquid according to claim 2. An anti-fogging film-forming base material comprising a base material and a film made of the urethane resin formed on the base material. In the film, a reaction product of an organic isocyanate and a surfactant having an isocyanate-reactive group. The antifogging film-forming substrate produced by the method for producing an antifogging film according to claim 3, wherein the product is dispersed and the reaction product is held during resin crosslinking.