JPH09220518A - Article bearing water-repelling coating film and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high durability and excellent transparency by applying emulsified water-repelling fine particles and resin to an article, drying, and hardening the applied emulsion. SOLUTION: This article bearing a water-repelling coating film is obtained by applying emulsified water-repelling fine particles and a resin to an article, drying and hardening the applied emulsion. In the composition of the water- repelling coating film, since the fine particles having extremely high water- repelling property exist in a hydrophilic components, as shown in the model illustration of the cross-section structure of the water-repelling coating film, the water-repelling particles in the coating film on the article are spontaneously gathered in the surface of the coating film near the air layer due to the function of surface energy and the density of the water-repelling fine particles in the coating film is low in the article side and increases slantingly toward the surface. Moreover, the polarity of the coating film composition is heightened by emulsifying the fine particles and such a structure can be materialized easily.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an article having a water-repellent coating and a method for producing the article.

[0002]

2. Description of the Related Art Conventionally, there has been used a technique of coating a surface of a building outer wall or a roofing material with a water-repellent material for the purpose of preventing stains such as rainwater and stains of interiors and furniture. . As the material having water repellency, an alkylsilicone-based resin or a fluorine-based resin is used. However, a coating material in which the above resin is dissolved has a problem in adhesiveness with a base material, and it is difficult to improve the adhesiveness with the base material. A separate process is required. In addition, the material itself is expensive, which is economically disadvantageous.

On the other hand, in recent years, there has been found a technique of exhibiting water repellency by using a coating material containing hydrophobic fine particles. For example, JP-A-3-215570 discloses a water-repellent coating material and a coating film in which hydrophobic fine particles having a surface tension of 32 dyn / cm or less are added to a resin having a water absorption rate of 0.5% or less. In addition, JP-A-4-45181
Japanese Patent Application Laid-Open No. 4-93597 and Japanese Patent Application Laid-Open No. 4-93597 disclose a water-repellent coating composition in which fine particles having a hydrophobic surface treatment are mixed with a silicone resin.

However, in the paint disclosed in Japanese Patent Application Laid-Open No. 3-215570, the surface tension is 32.
A method for producing fine particles having a dyn / cm or less is not disclosed. Further, the compositions disclosed in JP-A-4-45181 and JP-A-4-93597 provide water repellency by blending hydrophobic fine particles and forming fine irregularities on the surface. However, since it lowers transparency, it is not suitable for applications requiring designability such as outer walls and interiors.

[0005]

In view of the above problems, the present invention provides an article having a water-repellent coating excellent in durability and transparency.

[0006]

According to the present invention, an article obtained by emulsifying hydrophobic fine particles and a resin is applied to an article,
An article having a water-repellent coating obtained by drying and / or curing is provided.

The article on which the water-repellent coating of the present invention is formed is
The material is not particularly limited, and a plastic material such as a plastic plate or a film,
Inorganic materials such as wood plywood, cement and glass, ceramic-based materials such as roof tiles, metals and the like. The shape is not limited, and a plate-shaped product, a plate-shaped product having an embossed surface, a molded product molded into various shapes, and the like can be used.

<Hydrophobic fine particles> The hydrophobic fine particles used in the water-repellent coating of the present invention are selected from materials having extremely high hydrophobicity. Further, in order to impart transparency to the film, those having a particle diameter of the visible light or less are used. Specifically, the particle size is 300n
m or less, and more preferably 100 nm or less. Moreover, since those having a particle size of 5 nm or less are difficult to stably produce and are not practical, the average particle size of the hydrophobic fine particles used in the water-repellent coating of the present invention is 5 to 300 nm.
It is preferred that

It is preferable that the hydrophobic fine particles have a hydrophobic group bonded to the surface of silica fine particles synthesized while controlling the particle size. In addition, as particles having high hydrophobicity, there are fine particles of fluororesin, but it is difficult to control the particle diameter of the resin fine particles to 300 nm or less,
It is necessary to go through an extremely time-consuming process such as branching. On the other hand, alkylated silica fine particles whose average particle size is controlled to 5 to 300 nm are commercially available, but this does not reach the high water repellency required for the present invention.

The silica fine particles used as the hydrophobic fine particles of the present invention are produced by a method of adding a solution of a tetrafunctional silane compound such as tetraethoxysilane to an acidic or alkaline aqueous solution and stirring the mixture (wet method), and purification 4. Examples thereof include a method of burning hydrolysis of silicon chloride (sintering method) and the like. Among these methods, particle size control is relatively easy,
Since the highly reactive silanol groups are sufficiently present on the surface of the obtained silica fine particles, the amount of tetraethoxysilane etc.
A method of dropping a solution of the functional silane compound into an alkaline aqueous solution and stirring the mixture is advantageous. The particle size of the silica fine particles can be controlled by adjusting the alkali concentration of the alkaline aqueous solution and the reaction temperature in consideration of the stirring efficiency of the stirring device used.

As a method of bonding a hydrophobic group to the surface of the silica fine particles, perfluoro group, alkyl group, trimethylsilyl group, dimethylsilylene group, phenyl group, polydimethylsiloxane are added to silica fine particles having many silanol groups on the surface. Examples include reacting a compound containing a segment and the like. Silica fine particles having a perfluoroalkyl group bonded to the surface thereof have high hydrophobicity and are therefore particularly preferable as the hydrophobic fine particles of the present invention.

Various methods of the above surface perfluoroalkylation are known, and a method of condensing a metal alkoxy compound, a metal halogen compound, a metal isocyanate compound or the like having at least one perfluoroalkyl group on the surface of silica fine particles, Method with fluoroalkyl-containing surfactant, method with alcohol having fluoroalkyl group or alkyloxyethylene, method with polymer having fluoroalkyl group, plasma polymerized film on the surface in the presence of fluorine-containing gas The method of forming it may be mentioned. Among these, a metal alkoxy compound having a perfluoroalkyl group, a metal halogenated compound, and a metal isocyanate compound are preferable from the viewpoint of easy reaction control and stability of water repellency after treatment. Among these, those having silicon as a metal are advantageous from the viewpoint of availability because several kinds of perfluoroalkyl group-containing compounds are commercially available. Typical perfluoroalkyl group-containing compounds include 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, and 3,3,3-trifluoropropyltriisopropoxy. Silane, 3,
3,3-trifluoropropyltrichlorosilane, 3,
3,3-trifluoropropyltriisocyanate silane, 2-perfluorooctylethyltrimethoxysilane, 2-perfluorooctylethyltriethoxysilane, 2-perfluorooctylethyltriisopropoxysilane, 2-perfluorooctylethyltrichlorosilane , 2-perfluorooctylethyltriisocyanate silane and the like.

The surface hydrophobization of fine particles using the above-mentioned metal alkoxy compound having a perfluoroalkyl group, a metal halide compound, a metal isocyanate compound, etc., is carried out by adding a predetermined amount of peroxide to a solvent suspension of silica fine particles in alcohol or the like. It is carried out by adding a fluoroalkyl group-containing metal compound, stirring and drying. During stirring, heating may be performed up to the boiling point of the solvent. Reaction time is usually 3
It is adjusted according to the reactivity of the compound within the range of 0 minutes to 100 hours.

<Resin> The resin used in the water-repellent coating of the present invention is not particularly limited as long as it is soluble in a solvent or the like or has a proper fluidity by itself.
Examples of the resin include polymethylmethacrylate, polycarbonate, polyvinyl chloride and the like.

From the viewpoint of hardness and durability of the film, it is preferable to use a crosslinkable resin. Examples of the crosslinkable resin include epoxy resin, diallyl phthalate resin, silicone resin, phenol resin, unsaturated polyester resin, benzoguanamine resin, polyimide resin, polyurethane resin, melamine resin, urea resin, and (meth) acrylate resin. .

Due to the fact that high hardness can be realized and it can be easily cured by ultraviolet rays, electron beams, etc.
It is particularly preferable to use an acrylate having one or more (meth) acryloyl groups. Examples of the acrylate having two or more (meth) acryloyl groups in the molecule include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth). Acrylate, nonaethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, nonapropylene glycol di (meth) acrylate, polypropylene glycol di ( (Meth) acrylate, 2,2-bis [4- (acryloxydiethoxy) phenyl] propane, 2,2-bis [4- (methacryloxydiethoxy) phenyl] propa , 3-phenoxy-2-propanoyl acrylate,
Examples thereof include bifunctional (meth) acrylates such as 1,6-bis (3-acryloxy-2-hydroxypropyl) -hexyl ether. These can also be used for adjusting the viscosity of the coating composition.

Further, pentaerythritol tri (meth)
Trifunctional (meth) acrylates such as acrylate, trimethylolpropane tri (meth) acrylate, and glycerol tri (meth) acrylate, other pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) ) Acrylate, caprolactone-modified dipentaerythritol hexaacrylate obtained by reacting (meth) acrylic acid with a polyol obtained by adding ε-caprolactone to dipentaerythritol (commercially available as “DPCA series” from Nippon Kayaku Co., Ltd.), A tetra- or higher functional (meth) acrylate such as 1,1,3,3,5,5-hexa ((meth) acryloylalkylenedioxy) cyclotriphosphazene is advantageous for improving the film hardness.

Furthermore, when an acrylic urethane oligomer having a urethane bond in the molecule of an acrylic monomer is used, the abrasion resistance of the coating surface after curing is further improved. The urethane oligomer having an acryloyl group or a methacryloyl group at the molecular end can be obtained, for example, by reacting a compound having two or more isocyanate groups in one molecule with an acrylate or methacrylate having active hydrogen. Examples of the compound having two or more isocyanates in one molecule include m-phenylene diisocyanate, p-phenylene diisocyanate,
Toluene-2,4-diisocyanate, toluene-2,
6-diisocyanate, toluene-2,5-diisocyanate, toluene-3,5-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4 ′ -Diphenylmethane diisocyanate, 4,4'-diisocyanate-3,3'-dimethylbiphenyl, 4,4'-diisocyanate-3,3'-
Dimethylbiphenylmethane and the like can be mentioned. The above-mentioned active hydrogen-containing acrylate or methacrylate is 2
-Hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, glycerin di (meth) acrylate, 1,6-bis (3-acryloxy-
2-hydroxypropyl) -hexyl ether, pentaerythritol tri (meth) acrylate, tris-
(2-hydroxyethyl) -isocyanuric acid ester (meth) acrylate, (meth) acrylic acid, etc. are mentioned.

If desired, a polymerization initiator (crosslinking initiator) suitable for the resin may be added to the resin. For example, unsaturated polyesters, polyfunctional acrylates, and other resins that can react by a radical polymerization mechanism can be reacted with organic peroxides such as methyl ethyl ketone peroxide, benzoyl peroxide, cumene hydroperoxide, and lauroyl peroxide, and azobisisobutyrate. It can be thermally cured using an azo compound such as ronitrile. At this time, as a curing accelerator, cobalt naphthenate, cobalt octenoate, metal soaps such as manganese naphthenate, aromatic tertiary amines such as dimethylaniline, and quaternary ammonium salts such as dimethylbenzylammonium chloride are used. May be.

Further, for a resin which is cured through a radical polymerization mechanism and has a high reaction rate such as a polyfunctional acrylate, the following photopolymerization initiator is used to irradiate it with ultraviolet rays or visible rays. It can also be cured by. As the photopolymerization initiator, sodium methyldithiocarbamate sulfide, diphenyl monosulfide, sulfides such as dibenzothiazoyl monosulfide and disulfide; thioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,
Thioxanthone derivatives such as 4-diethylthioxanthone; azo compounds such as hydrazone and azobisisobutyronitrile; diazo compounds such as benzenediazonium salts; benzoin, benzoin methyl ether, benzoin ethyl ether, benzophenone, dimethylaminobenzophenone, Michler's ketone, benzylanthraquinone , T
-Butyl anthraquinone, 2-methyl anthraquinone,
Aromatic carbonyl compounds such as 2-ethylanthraquinone, 2-aminoanthraquinone and 2-chloroanthraquinone; methyl p-dimethylaminobenzoate, ethyl p-dimethylaminobenzoate, butyl p-dimethylaminobenzoate, p-diethylaminobenzoic acid Dialkylaminobenzoic acid esters such as isopropyl; peroxides such as benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, cumene hydroperoxide; 9-phenylacridine, 9-p-methoxyphenylacridine, 9 Acridine derivatives such as acetylaminoacridine and benzacridine; 9,10-dimethylbenzphenazine, 9-methylbenzphenazine,
Phenazine derivatives such as 10-methoxybenzphenazine; quinoxaline derivatives such as 6,4 ′, 4 ″ -trimethoxy-2,3-diphenylquinoxaline; 2,4,5-
Triphenylimidazoyl dimer, 2-nitrofluorene, 2,4,6-triphenylpyrylium boron tetrafluoride salt, 2,4,6-tris (trichloromethyl) -1,
Examples include 3,5-triazine, 3,3′-carbonylbiscoumarin, thiomichler ketone and the like.

The addition amount of the above-mentioned polymerization initiator is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the crosslinkable resin which is the object of the polymerization. This is because if the addition amount is too small, the reaction will be slow and uncured, and the crosslinking will require heating or light irradiation for a long time. If the amount added is too large, the weather resistance of the resin after curing will decrease, and yellowing tends to occur, such being undesirable. Instead of adding a polymerization initiator, it is possible to carry out crosslinking with a high energy ray such as electron beam or radiation.

Further, an amine compound may be added in order to prevent a decrease in sensitivity due to oxygen inhibition. The amine compound is not particularly limited as long as it is a non-volatile compound such as an aliphatic amine or an aromatic amine. For example, triethanolamine and methyldiethanolamine are often used. As the photopolymerization initiator, from the above examples,
The above object can be achieved by using an amino group-containing one such as dialkylaminobenzoic acid ester and Michler's ketone.

<Surfactant> In recent years, in view of prevention of environmental pollution and safety during production or work, it has been required to make paints and film-forming substances nonsolvent. In order to meet these requirements, in the present invention, it is preferable to form a film with a so-called water-based emulsion paint in which the paint is dispersed in water.

At this time, a surfactant is added for the purpose of facilitating the dispersion of the coating material in water, improving the coating property when coating the emulsified composition on the article surface, and suppressing foaming. To do. The above-mentioned surfactants are nonionic surfactants, anionic surfactants, cationic surfactants,
Amphoteric surfactants and the like can be used.

Examples of the nonionic surfactants include ether types such as polyoxyethylene alkylphenyl ether and polyoxyethylene alkyl ether, ester types such as glycerin fatty acid ester, sorbitan fatty acid ester and sucrose fatty acid ester, polyethylene glycol fatty acid ester, Examples thereof include ester ether type such as polyoxyethylene sorbitan fatty acid ester and fatty acid alkanolamide type.

As the anionic surfactant, a carboxylic acid type such as fatty acid monocarboxylic acid salt and N-acylloylglutamate, an alkyl sulfonate, an alkylbenzene sulfonate, a naphthalene sulfonate-formaldehyde condensate, and a sulfosuccinate. Examples thereof include sulfonic acid type such as acid dialkyl ester, sulfuric acid ester type such as alkyl sulfate salt, and phosphoric acid ester type such as alkyl phosphate salt. As the cationic surfactant, an amine salt type such as an alkylamine salt, an alkyltrimethylammonium salt,
Examples thereof include quaternary ammonium salt type compounds such as dialkyldimethylammonium salt and alkyldimethylbenzylammonium salt.

As the amphoteric surfactant, carboxybetaine type such as betaine N, N-dimethyl-N-alkylaminoacetate, 2-alkyl-1-hydroxyethyl-1-
Examples thereof include glycine type ones such as carboxymethylimidazolinium betaine.

Among the above surfactants, those in which hydrogen in the alkyl group portion is replaced with fluorine are particularly preferable in order to improve the dispersibility and dispersion stability of the surfactant.

<Water> Water used in the present invention is not particularly limited, but when an anionic surfactant is used, it contains a cationic metal salt such as calcium.
So-called hard water is not preferred. Although a chelating agent may be used to trap undesired ions, it is convenient to use ion-exchanged water or distilled water that does not contain these.

<Additives> In the water-repellent coating composition of the present invention, in addition to the above-mentioned components, various kinds of pigments, thixotropic agents, fillers, ultraviolet absorbers, antioxidants, surface modifiers, degutting agents, etc. Additives may be added.

Further, the viscosity of the composition can be adjusted by adding a solvent and a thickener so that the work of forming a water-repellent coating on the article surface becomes easy. As the above-mentioned solvent, a solvent having a low boiling point or a solvent having a strong volatility evaporates during the construction to change the viscosity, and a solvent having a high boiling point requires a time for the drying step, and thus a solvent having a boiling point of about 60 to 160 ° C is desirable. . Specifically, cyclohexanone, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), diethylene glycol dimethyl ether, tetrahydrofuran, dioxane, butyl acetate, ethyl acetate, methyl isopropyl ketone, methyl ethyl ketone, toluene, xylene,
Examples include anisole, methanol, ethanol, isopropanol, butanol and the like. As the thickener, a polymer or the like which can be dissolved in a solvent is used, for example, an acrylic resin
Acrylic silicon resin, polysiloxane resin, fluororesin, vinyl chloride-vinyl acetate copolymer and the like are preferably used.

<Method for producing coating composition> The coating composition of the present invention can be obtained by mixing and stirring the above-mentioned hydrophobic fine particles, resin, water, surfactant, and other additives. At this time, it is preferable to add 0.1 to 200 parts by weight of the hydrophobic fine particles to 100 parts by weight of the resin, and more preferably 1 to 100 parts by weight.
This is because if the proportion of the hydrophobic fine particles is too large, it may cause deterioration of transparency and embrittlement of the film after formation, and if it is too small, water repellency cannot be exhibited.

The mixing method is not particularly limited, but generally, the hydrophobic fine particles are dispersed in a solvent in advance, and thereafter, a crosslinking agent, a thickener, and various additives are added. A general stirring device such as a mechanical stirrer or a mixer can be used for stirring, and if necessary, heating may be performed during dispersion or stirring.

The above coating composition is emulsified by vigorous stirring. At the time of emulsification, not only a method of stirring after mixing all components of the water-repellent composition, but also adding only the crosslinking agent to the mixture after stirring beforehand, or adding particles alone or particles and a solvent later. Further, various methods such as stirring can be adopted, and the order of introducing the materials can be arbitrarily selected depending on the apparatus used and the viscosity of the composition.

The amount of the above-mentioned surfactant added is required to be higher than the critical micelle concentration and is determined by the kind of the surfactant. Further, since the water repellency of the coating material is deteriorated when the surfactant is present in excess, it is preferable that the addition amount does not exceed 50% by weight of the solid content.

In the emulsification, the mixing ratio of the solid content and water in the coating composition is such that the solid content is 0.5 to
It is preferably 50% by weight. This is because if the solid content is too small, the shearing effect is reduced and the efficiency is reduced, and if it is too large, the viscosity becomes too high and it becomes difficult to emulsify and disperse by shearing. After dispersion,
Water can be added to dilute the emulsion as long as the stability of the emulsion is not impaired.

As a stirring device for carrying out the emulsification, a high speed emulsifying machine, a pressure kneader, a colloid mill,
A high speed stirring shaft, a sonicator, etc. can be used. The time required for the stirring varies depending on the device, but it is preferable to select the shortest time for stable emulsion formation.

<Film Formation> The obtained water-repellent film composition is applied to the surface of an article and dried and / or cured to form a film. For the coating, an appropriate method can be used depending on the physical properties of the coating composition and the article. Generally, brush coating, spray coating method, curtain coating method, flow coating method, bar coating method, doctor blade method, roll coating method, dip coating method, air knife method, spin coating method and the like are used. The film thickness of the film can be changed as necessary. Generally, it is between 1 μ and 1 mm, but is not limited to this. The film provided on the surface of the article may be dried as it is, or by heat,
It may be cured by light, high energy rays or the like.

<Structure of coating> In order to more effectively develop water repellency by the blended hydrophobic fine particles, it is preferable that many hydrophobic fine particles are present on the surface of the coating. If the amount of the hydrophobic fine particles present in the entire film is increased, the amount of the fine particles existing on the surface of the film can be increased accordingly, but there are disadvantages that the film becomes brittle or becomes opaque.

In the water-repellent coating composition of the present invention, since very fine particles having extremely high hydrophobicity are present in the hydrophilic component, the surface fine particles serve to provide hydrophobic fine particles in the coating formed on the article. However, the structure is such that the density of the hydrophobic fine particles existing in the film spontaneously gathers on the surface of the film close to the air layer, and the density is small on the article side, and the density gradually increases toward the film surface. Furthermore, the emulsification increases the polarity of the coating composition, making it easier to realize the above structure.

A schematic view of the cross-sectional structure of the water-repellent coating of the present invention is shown in FIG. The density of the hydrophobic fine particles shown by the circle is small on the article side, and increases gradually toward the film surface. With such a structure, water repellency can be imparted to the article surface without extremely increasing the amount of the hydrophobic fine particles in the entire film. For this reason, not only does it not have the above-mentioned drawbacks, but the objective can be effectively achieved with a smaller amount of hydrophobic fine particles. Further, since only a very small amount of hydrophobic fine particles are present on the surface where the coating film and the article come into contact with each other, it is possible to handle it in the same manner as a normal resin without requiring treatment for improving the adhesion.

In order to obtain the above effect, it is preferable that 50 to 100% by weight of the coating content of the hydrophobic fine particles is contained in the thickness portion of 30% from the surface of the coating. This condition can be achieved by the method for producing a coated article.

<Hydrophobic fine particles having a crosslinkable group> The water-repellent coating formed by the method of the present invention has an ideal structure in which most of the hydrophobic fine particles are present near the surface of the coating, as described above. However, the presence of a large amount of fine particles on the surface may be disadvantageous depending on the environment to be placed after the production and the combination with the resin, which may cause whitening of the film surface.

In order to prevent whitening of the surface of the film and to stably maintain the structure in which the hydrophobic fine particles are inclined toward the surface, a crosslinkable group is introduced into the fine particle surface, and The resin in the film-forming product can be crosslinked.
Crosslinking of the crosslinkable group on the surface of the fine particles and the resin in the coating composition,
At the same time, it has the effect of improving the surface hardness of the film. Therefore, a surface having excellent abrasion resistance and transparency can be obtained by the above crosslinking.

The combination of the crosslinkable group and the resin may be arbitrarily selected from those generally known to carry out a crosslinking reaction. The silica fine particles mentioned as a suitable example above have silanol groups with high reactivity on the surface, and are therefore advantageous in introducing a crosslinkable group.

In order to introduce a crosslinkable group onto the surface of the above-mentioned silica fine particles, a portion which reacts with a silanol group in one molecule,
A compound having both crosslinkable groups may be used by reacting with a silanol group. Examples of compounds that react with silanol groups include silane coupling agents and isocyanate compounds. As the crosslinkable group, those having a double bond at the terminal of the molecular chain such as vinyl group, acryloyl group and methacryloyl group can be used. Specifically, a silane coupling agent such as γ-methacryloyloxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane as a compound that reacts with the silanol group; methacryloyl isocyanate, methacryloyloxyethyl. Examples thereof include isocyanate compounds such as isocyanate.

The crosslinkable groups that can be used differ depending on the combination with the resin. For example, for epoxy resins, epoxy groups can be used in addition to those exemplified above. Examples of the compound having an epoxy group and reacting with a silanol group include γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldimethoxysilane.

The amount of the crosslinkable group to be introduced should be adjusted within the range where hydrophobicity is a dominant property of the surface of the fine particles.
In the case of surface perfluoroalkylated silica fine particles, the molar ratio of the crosslinkable group to the perfluoroalkyl group introduced on the surface is preferably in the range of 0.01 to 1.

When a crosslinkable group is introduced into the hydrophobic fine particles, it can be used as a resin in the film-forming material to form a film.
It is necessary to use one that involves a chemical reaction (so-called polymerizable one). The usual thermosetting resin and photocurable resin correspond to this. The chemical reaction is not limited to the resin alone, and the chemical reaction may be performed by an additive such as a polymerization initiator. A step of reacting the crosslinkable group on the surface of the hydrophobic fine particles may be performed separately from the step of forming a film by drying and / or curing, but if the object of the present invention is achieved, the step of simultaneously forming the film may be performed. It would be convenient to carry out the above crosslinking.

Specific examples of the resin suitable for carrying out the above-mentioned crosslinking are the same as those exemplified above as the "crosslinkable resin". By simultaneously achieving the cross-linking with the surface of the hydrophobic fine particles and the cross-linking of the resin itself, it is possible to obtain a film having high hardness and excellent durability.

Besides, it is the same that a polymerization initiator or the like can be added depending on the resin used, and a plurality of resins can be mixed and used. When a plurality of resins are mixed and used, at least one of them may be one that involves the above chemical reaction.

[0052]

【Example】

Example 1 <Synthesis of Silica Fine Particles> A solution prepared by mixing 40 g of tetraethoxysilane (manufactured by Nacalai Tesque, Inc.) with 200 ml of methanol (manufactured by Nacalai Tesque, Inc.) was mixed with 475 m of methanol.
1 and 28% ammonia solution (manufactured by Nacalai Tesque) 6
A solution in which fine silica particles were suspended was obtained by adding dropwise to 0 ml of the mixed solution while stirring with a mechanical stirrer (manufactured by Shinto Scientific Co., Ltd.). The ammonia and methanol components in this solution were replaced by ethanol (Nacalai Tesque, Inc.) by distillation.

<Perfluoroalkylation of Silica Fine Particles> To 100 parts by weight of the silica fine particles obtained above, 0.1 part by weight of 2-perfluorooctylethyltrichlorosilane (manufactured by Toshiba Silicone Co., Ltd.) was added and heated under reflux for 12 hours. By doing so, a suspension of silica fine particles having a 2-perfluorooctylethyl group introduced on the surface was obtained. This was evaporated to dryness to obtain silica fine particles whose surface was perfluoroalkylated.

<Measurement of Particle Size of Silica Fine Particles> The silica fine particles obtained by the above method were dispersed on a glass substrate to which a double-sided tape was attached in advance and photographed with a scanning electron microscope. The particle size of the particles shown in this photograph was directly measured and the average particle size was determined.
m.

<Preparation of Water-Repellent Film Composition> Caprolactone-modified dipentaerythritol hexaacrylate as an acrylic monomer (Kayarad DPC manufactured by Nippon Kayaku Co., Ltd.)
A-30) 100 parts by weight, 2,4-diethylthioxanthone as a photo-curing agent (manufactured by Nippon Kayaku Co., Kayakyu DE
TX) 5 parts by weight, ethyl 4-dimethylaminobenzoate as a photo-curing accelerator (manufactured by Nippon Kayaku Co., Kayakyu EP
A) 5 parts by weight, 10 parts by weight of sodium perfluoroundecanoate (manufactured by Daikin Fine Chemical Laboratories, Inc., product number C-2000) as a surfactant, and 500 parts by weight of water were mixed, and a sonicator (manufactured by Nippon Seiki Seisakusho, US60) was mixed.
It was emulsified by treating it with 0T and a tip of 20 mmφ for 60 seconds. On the other hand, 20 parts by weight of the fine particles of perfluoroalkylated silica, 500 parts by weight of toluene, and 10 parts by weight of a surfactant (sodium perfluoroundecanoate) were mixed, and a sonicator (manufactured by Nippon Seiki Seisakusho Ltd., US6) was mixed.
00T, chip 20 mmφ) for 60 seconds for emulsification. The above two emulsion solutions were combined and stirred to obtain a water repellent coating composition.

<Formation of film> The above water-repellent film composition was applied onto a polymethylmethacrylate resin plate having a thickness of 3 mm by using a brush and light irradiation (1,0) with a metal halide lamp.
To 100 mJ / cm ² ) to prepare a resin plate having a water-repellent coating. When the film thickness of the above film was confirmed by a scanning electron microscope, it was 3 μm.

Example 2 The same as Example 1 except that 30 ml of aqueous ammonia and 0.4 wt% of 2-perfluorooctylethyltrichlorosilane were added to the silica particles during the perfluoroalkylation of the silica particles. Fine particles were synthesized. The average particle size of the obtained fine particles was 50 nm. Example 1
A film was formed in the same manner as in 1. to produce a resin plate having a water-repellent film.

Example 3 Similar to Example 1, except that 15 ml of ammonia water and 2.2 wt% of 2-perfluorooctylethyltrichlorosilane were added to the silica fine particles during the perfluoroalkylation of the silica fine particles. Fine particles were synthesized. The average particle size of the obtained fine particles was 30 nm. Example 1
A film was formed in the same manner as in 1. to produce a resin plate having a water-repellent film.

Example 4 100 parts by weight of caprolactone-modified dipentaerythritol hexaacrylate, 5 parts by weight of 2,4-diethylthioxanthone, 5 parts by weight of ethyl 4-dimethylaminobenzoate, 2 parts by weight of sodium perfluoroundecanoate, 2000 parts by weight of water. The parts were mixed and treated with a sonicator for 60 seconds to emulsify. Fine particles of perfluoroalkylated silica prepared in Example 1 (particle size 100 nm)
10 parts by weight, 500 parts by weight of toluene, and 2 parts by weight of sodium perfluoroundecanoate were mixed and treated with a sonicator for 60 seconds to emulsify. The above two emulsion solutions were combined and stirred, and the obtained water-repellent film composition was subjected to film formation in the same manner as in Example 1 to prepare a resin plate having a water-repellent film.

Example 5 100 parts by weight of caprolactone-modified dipentaerythritol hexaacrylate, 5 parts by weight of 2,4-diethylthioxanthone, 5 parts by weight of ethyl 4-dimethylaminobenzoate, 10 parts by weight of sodium perfluoroundecanoate,
6400 parts by weight of water was mixed and treated with a sonicator for 60 seconds to emulsify. Perfluoroalkylated silica fine particles (particle size 50 nm) 2 prepared in Example 2
0 parts by weight, 500 parts by weight of toluene and 20 parts by weight of sodium perfluoroundecanoate were mixed and treated with a sonicator for 60 seconds to emulsify. The above two emulsion solutions were combined and stirred, and the obtained water-repellent film composition was subjected to film formation in the same manner as in Example 1 to prepare a resin plate having a water-repellent film.

Example 6 <Perfluoroalkylation of silica fine particles> 100 parts by weight of silica fine particles obtained by the same method as in <Synthesis of silica fine particles> of Example 1 was used to prepare 2-perfluorooctylethyltrimethoxysilane ( 160 parts by weight of Toshiba Silicone Co., Ltd.) was added, and the mixture was heated under reflux for 4 hours to obtain a suspension of silica fine particles having a 2-perfluorooctylethyl group introduced on the surface. This was evaporated to dryness to obtain surface perfluoroalkylated silica fine particles.

<Measurement of Particle Diameter of Silica Fine Particles> The average particle diameter of the silica fine particles was determined by the same method as in Example 1 and found to be 60 nm.

<Preparation of Water Repellent Film Composition> Caprolactone-modified dipentaerythritol hexaacrylate as an acrylic monomer (Kayarad DPC manufactured by Nippon Kayaku Co., Ltd.
A-30) 100 parts by weight, as a surfactant 10 parts by weight of sodium perfluoroundecanoate (manufactured by Daikin Fine Chemicals Ltd., product number C-2000), water 800
0 parts by weight were mixed and treated with a sonicator (manufactured by Nippon Seiki Seisakusho, US600T, chip 13 mmφ) for 60 seconds to emulsify. On the other hand, 20 parts by weight of the above silica fine particles, 500 parts by weight of toluene, and 10 parts by weight of a surfactant (sodium perfluoroundecanoate) were mixed to obtain a sonicator (manufactured by Nippon Seiki Seisakusho, US600).
T, tip 13 mmφ) for 60 seconds for emulsification. The above two emulsion solutions were combined and ultrasonically stirred to obtain a water repellent coating composition.

<Formation of film> The above water-repellent film composition was applied onto a polymethylmethacrylate resin plate having a thickness of 3 mm with a brush and irradiated with light from a high pressure mercury lamp (5,000 m).
J / cm ² ) to prepare a resin plate having a water-repellent coating. When the film thickness of the above film was confirmed by a scanning electron microscope, it was 3 μm.

Example 7 <Introduction of crosslinkable group into perfluoroalkylated silica fine particles> Surface fluoroalkylated silica fine particles 1 obtained by <Perfluoroalkylation of silica fine particles> in Example 6
To 00 parts by weight, 30 parts by weight of γ-methacryloyloxypropyltrimethoxysilane (manufactured by Toray Dow Corning Silicone Co., Ltd.) was added, and the mixture was heated and refluxed for 4 hours to give fluoroalkyl groups and γ-methacryloyloxypropyl groups on the surface. A suspension of the introduced silica fine particles was obtained. This was evaporated to dryness, and silica fine particles surface-perfluoroalkylated and having a crosslinkable group introduced were obtained.

<Measurement of Surface State of Silica Fine Particles> FT-IR of the above-mentioned silica fine particles perfluoroalkylated and having a crosslinkable group introduced therein and silica fine particles not subjected to these treatments were measured. Compared. FIG. 2 shows the measurement results. The above is the measurement result of the silica fine particles that have not been subjected to the above treatment, but compared with this, 115 derived from the C—F bond by the surface perfluoroalkylation treatment.
Peak near 0 cm ^−1, C = due to treatment for introducing crosslinkable group
A peak around 1650 cm ⁻¹ derived from C bond is observed.

<Measurement of Particle Size of Silica Fine Particles> The average particle size of the silica fine particles was determined in the same manner as in the above method, and was found to be 60 nm.

<Preparation of Water-Repellent Film Composition and Film Formation> A film was formed in the same manner as in Example 6 by using the above-mentioned fine particles of perfluoroalkylated silica and having a crosslinkable group introduced, to form a film. A resin plate having an aqueous film was prepared.

Examples 8 and 9 In the preparation of the water-repellent coating composition in Example 7, the amount of water added was 17,000 parts by weight in Example 7 and 98,000 parts by weight in Example 8. A film was formed in the same manner as in No. 7, to prepare a resin plate having a water-repellent film.

Example 10 Except that DPR-047 (manufactured by Nippon Kayaku Co., Ltd.) was used in place of DPCA-30 as the acrylic monomer in <Preparation of water-repellent coating composition> in Example 7.
A film was formed in the same manner as in Example 7 to produce a resin plate having a water repellent film.

Example 11 The procedure of <Preparation of water-repellent coating composition> in Example 7 was repeated except that DPR-047 was used in place of DPCA-30 as the acrylic monomer, and the amount of water added was 98,000 parts by weight. Perform film formation as in Example 7,
A resin plate having a water repellent film was produced.

Comparative Example 1 Silica fine particles obtained by the method of <Synthesis of silica fine particles> of Example 1 were subjected to surface perfluoroalkylation treatment and cross-linkable group introduction treatment, and the silica fine particle suspension solution was evaporated as it was. A resin plate having a water-repellent coating was prepared in the same manner as in Example 7, except that the water-repellent coating composition was prepared using the dried product.

Comparative Example 2 The silica fine particles obtained by the method of <Synthesis of silica fine particles> of Example 1 were subjected to surface perfluoroalkylation treatment, and the silica fine particle suspension solution was evaporated to dryness as it was. A resin plate having a water-repellent coating was produced in the same manner as in Example 1 except that the water-repellent coating composition was prepared.

Comparative Example 3 Example 1 was repeated except that fluorinated graphite (Cefbon CMA, manufactured by Central Glass Co., average particle size 1 to 2 μ) was used in place of the perfluoroalkylated silica fine particles used in Example 1. A resin plate having a water-repellent film was prepared in the same manner as in.

Comparative Example 4 The same as Example 1 except that the perfluoroalkylated silica fine particles used in Example 1 were replaced with alkylated silica fine particles (AEROSIL R972D manufactured by Nippon Aerosil Co., Ltd., particle size 14 nm). Then, a resin plate having a water-repellent film was produced.

The water-repellent coatings produced in the examples and comparative examples were evaluated as follows. The results are shown in Table 1.

<Evaluation of water repellency> Distilled water was dropped on the surface of the water repellent film, and the contact angle was measured using a contact angle meter (CA-X manufactured by Kyowa Interface Science Co., Ltd.).

<Evaluation of Transparency> Printed matter (character size 9
The acrylic plate was placed on top of (point) with the coated surface facing up, and the visibility of the printed characters was visually determined. Those that could see the letters were marked with ◯, and those that could not be seen were marked with x.

<Evaluation of Scratch Resistance> The scratch resistance of the surface of the water-repellent coatings of Examples 6 to 11 was measured by a scratch tester (manufactured by Lesca, CSR-02, needle used: 212 gf / mm,
The contact angle was measured using a radius of curvature: 15 μm). Generation of white powder was observed on the surface of Example 6 in which the crosslinkable group was not introduced, but it was not observed on the surface of Examples 7 to 11 using silica fine particles into which the crosslinkable group was introduced. It was

[0080]

[Table 1]

<Measurement of coating structure> Secondary ion mass spectrometer (SIMS: A-DIDA30 manufactured by Atomika)
00) was used to measure the depth profile (element abundance ratio in the depth direction) in the entire thickness of the water-repellent coating of Example 2. The results are shown in FIG.

When calculated from the integral of the element distribution in FIG. 3, the elemental content of fluorine and silicon derived from the hydrophobic fine particles was reduced to 900 nm on the surface (thickness of 30% from the surface) with respect to the total film thickness of 3 μm. About 90% of the content was shown, and it was confirmed that a large amount of hydrophobic fine particles were present on the surface of the water-repellent film in an inclined manner.

[0083]

The water-repellent film of the present invention can simultaneously realize excellent water repellency and transparency. In addition, by using a composition in which fine particles having high hydrophobicity are present in the hydrophilic component as an emulsion, the action of surface energy allows hydrophobic fine particles to be present at a high concentration on the surface of the formed film. I can. Therefore, water repellency can be imparted to the surface of the article without extremely increasing the amount of the hydrophobic fine particles in the entire film. Therefore, not only does it not have a defect such as embrittlement of the film, but also a smaller amount of the hydrophobic fine particles can effectively achieve the purpose. Further, since only a very small amount of hydrophobic fine particles are present on the surface where the coating film and the article come into contact with each other, there is no need to perform a treatment for improving the adhesion. further,
By using silica fine particles having a crosslinkable group introduced on the surface, the surface hardness of the film is improved and a surface having excellent scratch resistance and transparency is realized. At the same time, it is possible to stably maintain the state in which the hydrophobic fine particles are present at the above-mentioned high concentration and prevent whitening of the surface.

[0084]

[Brief description of drawings]

FIG. 1 is a schematic diagram of a cross-sectional structure of a water-repellent coating of the present invention.

FIG. 2 is a measurement diagram of FT-IR in Example 6 of the present invention.

FIG. 3 is a structural measurement diagram of a film in Example 2 of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09D 201/00 PDC C09D 201/00 PDC (72) Inventor Masatoshi Murashima Hyakusan, Shimamoto-cho, Mishima-gun, Osaka Prefecture 2-1 Sekisui Chemical Co., Ltd.

Claims (6)

[Claims] 1. An article having a water-repellent film obtained by applying an emulsion of hydrophobic fine particles and a resin to an article, and drying and / or curing the article. 2. An article in which a coating film composed of hydrophobic fine particles and a resin is laminated, and 50 to 100% of the coating content of the hydrophobic fine particles is provided in a portion 30% in thickness from the surface of the coating film.
An article having a water-repellent coating, characterized in that the content of the water-repellent coating is in the range of% by weight. 3. The article having a water-repellent film according to claim 1, wherein the hydrophobic fine particles are surface perfluoroalkylated silica fine particles. 4. The article having a water-repellent coating according to claim 1, wherein a crosslinkable group is introduced on the surface of the hydrophobic fine particles. 5. The average particle size of the hydrophobic fine particles is 5 to 300 n.
The article having the water-repellent film according to any one of claims 1 to 4, wherein m is m. 6. A method for producing an article having a water-repellent film, which comprises applying an emulsion of hydrophobic fine particles and a resin to an article, and drying and / or curing the article.