JP7042695B2 - Film formation method - Google Patents

Description

The present invention relates to a novel film forming method.

Conventionally, in the exterior of buildings and civil engineering structures, various coating materials are formed on various base materials for the purpose of protecting the base materials and imparting color. From the viewpoint of aesthetics and the like, such a coated surface may be provided with an uneven pattern or a multicolored pattern. However, such a coated surface tends to deteriorate due to the influence of sunlight, rainfall, etc. when exposed outdoors for a long period of time. Specifically, discoloration, cracks, etc. may be caused. Therefore, it becomes necessary to repaint the coated surface (existing coated surface) in which such deterioration has occurred.

On the other hand, in recent years, there has been a movement to repaint the existing coating surface to improve the aesthetic appearance and extend the life of the base material. For example, Patent Document 1 describes a method of polishing a deteriorated portion of the surface of a ceramic exterior wall material coating layer and then applying a transparent coating agent to restore the original color tone.

Japanese Unexamined Patent Publication No. 2001-227138

By the way, among the existing coated surfaces as described above, those having an uneven pattern have a partial difference in the way sunlight hits, the way water flows, the degree of retention, etc., depending on the shape of the unevenness. Become. Therefore, in a part where the load due to sunlight or water is large, deterioration is likely to proceed, and there is a possibility that discoloration, cracks, etc. may be locally caused. Further, if the durability of the film surface having a multicolor pattern differs depending on the color tone, the same deterioration may occur in the region of the color tone in which the durability is relatively insufficient.

Even if such an existing coated surface is repainted by the method described in the above patent document, the progress of deterioration of the existing coated surface cannot be sufficiently suppressed, and the effect of repainting can be obtained. It may be difficult to get a patent.

The present invention has been made in view of such problems, and while utilizing the uneven pattern and the multicolored pattern of the existing coating film, it suppresses the progress of deterioration such as discoloration and cracking caused by the existing coating film, and provides aesthetic appearance for a long period of time. It is an object of the present invention to provide a film forming method which can be retained.

In order to solve such a problem, as a result of diligent studies, the present inventor has applied a specific coating material to an existing coating surface having an uneven pattern and / or a multicolor pattern to form a coating. And came to complete the present invention.

That is, the present invention has the following features.
1. 1. It is a film forming method for forming a new film by applying a coating material having visible light transmission to an existing film surface provided on a base material.
The existing coated surface has an uneven pattern and / or a multicolored pattern.
The above-mentioned covering material is
It contains a resin component containing 20% by weight or more of (meth) acrylic acid alkyl ester (A) having an alkyl group having 3 or more carbon atoms in the resin constituent component, has a long-wave ultraviolet transmittance of 40% or less, and transmits medium-wave ultraviolet light. A film forming method characterized by forming a film having a ratio of 20% or less.
2. 2. The above-mentioned covering material is
The (meth) acrylic acid alkyl ester (A) having an alkyl group having 3 or more carbon atoms is characterized by containing a (meth) acrylic acid alkyl ester (a1) having an alkyl main chain having 3 or more carbon atoms. 1. 1. The film forming method according to the above.
3. 3. The new coating is characterized by having a film thickness of 30 μm or more. Or 2. The film forming method according to.

According to the film forming method of the present invention, it is possible to suppress the progress of deterioration such as discoloration and cracks caused by the existing film while utilizing the uneven pattern and the multicolor pattern of the existing film, and maintain the aesthetic appearance for a long period of time. ..

Hereinafter, embodiments for carrying out the present invention will be described.

The present invention is a coating method for forming a new coating by applying a specific coating material to an existing coating surface (an existing coating surface having an uneven pattern and / or a multicolor pattern) provided on a substrate. be.

Even if such an existing coating surface is repainted with a conventional transparent coating agent, it is difficult to suppress the progress of discoloration, cracks, etc. in the portion that is originally prone to deterioration, and for cracks, the existing coating is used. There is a possibility that fine cracks on the surface will progress over time. Such cracks are likely to spread to the coating film after repainting, which impairs the aesthetic appearance, water impermeability, etc. of the newly formed coating film, and makes it difficult to obtain a sufficient effect in terms of extending the life of the base material.

On the other hand, in the present invention, it is possible to suppress the progress of deterioration such as discoloration and cracks caused by the existing coating surface and maintain the aesthetic appearance for a long period of time while utilizing the uneven pattern and the multicolor pattern of the existing coating surface. It is also possible to extend the life of the base material. It is considered that such an effect is achieved by sufficiently imparting resistance to sunlight and water by the specified new coating film of the present invention.

In the present invention, the existing coating surface provided on the substrate is targeted for coating. Examples of such an existing coating surface include those formed on the surface of a base material such as a building or a civil engineering structure, and in particular, an exterior surface (outer wall, roof, etc.) that is easily affected by sunlight, water, or the like. ) Is preferable. Examples of the base material include concrete, mortar, plate-like base material and the like. Among these, as the plate-shaped base material, for example, cement board, extruded board, slate board, PC board, ALC board, fiber reinforced cement board, metal siding board, ceramic siding board, ceramic board, calcium silicate board, etc. Examples include plastic boards, hard wood piece cement boards, PVC extruded siding boards, plywood and the like. The present invention is particularly useful when the substrate is a plate-like substrate.

When the existing coated surface is composed of a plurality of plate-shaped base materials, the joints between the plate-shaped base materials may be filled with joint materials such as a sealing material and a dry joint material. Among these, the sealing materials include, for example, silicone-based sealing materials, modified silicone-based sealing materials, polysulfide-based sealing materials, modified polysulfide-based sealing materials, acrylic urethane-based sealing materials, polyurethane-based sealing materials, SBR-based sealing materials, and butyl rubber-based sealing materials. Materials and the like can be mentioned.

The existing coated surface has an uneven pattern and / or a multicolor pattern. Such an existing coating is formed by one kind or two or more kinds of coating agents. Various coating agents such as colored or non-colored, opaque or transparent can be used. For example, vinyl acetate resin, alkyd resin, epoxy resin, acrylic resin, urethane resin, acrylic silicon resin, silicon resin, fluororesin, etc. can be used. And the like containing one or more kinds of resins selected from the above. The existing coating surface is one layer or two or more coatings, and may be, for example, one in which a colored coating layer, a transparent coating layer, or the like is laminated.

Examples of uneven patterns include tile-like patterns, brick-like patterns, stone-grain patterns, rock-like patterns, wood-grain patterns, geometric patterns, striped patterns, lattice patterns, polka dots patterns, and sand wall patterns. , Yuzu skin pattern, ripple pattern, etc., as well as graphic patterns designed with animals and plants. Specifically, examples of the shape of the convex portion when the uneven pattern is viewed from the front include a square, a rectangle, a circle, an ellipse, a triangle, a rhombus, a polygon, and an irregular shape. Examples of the cross-sectional shape of the convex portion in the uneven pattern include a trapezoid, a square, a rectangle, a semicircle, a corrugated shape, a stepped shape, a triangle, a chevron shape, and an irregular shape. The concave portion in the uneven pattern may be flat and form a joint or the like. The height difference between the concave portion and the convex portion may be constant or different in each portion, but is preferably 20 mm or less, more preferably about 1 to 15 mm. Such an uneven pattern may be applied to either one or both of the base material and the existing coating film.

A multicolor pattern is a pattern in which at least two or more colors are visibly mixed. For example, a pattern in which two or more colors are mixed, or spots (one color or two or more colors) are scattered on a background color. Patterns that are painted in two or more colors (for example, island-like pattern, linear pattern, tile-like pattern, brick-like pattern, stone-grain pattern, rock-like pattern, wood-grain pattern, geometric pattern, stripes Patterns, checkered patterns, random patterns, etc.) and the like. Such a multicolor pattern may be formed by, for example, various printing methods (inkjet printing or the like), or may be formed by a decorative coating agent such as a stone-like finish coating material or a multicolored pattern paint. It may be.

INDUSTRIAL APPLICABILITY The present invention can be preferably applied as a repainting method (remodeling method) when the existing coated surface deteriorates over time as described above. The degree of deterioration over time is not particularly limited, but a wall surface that has been used for about 5 years or more (further, 8 years or more) is suitable as the object of the present invention. Before the formation of the new coating, the existing coating surface can be cleaned or partially repaired, if necessary. If the existing coating surface has a joint material such as a sealing material, the existing joint material may be left as it is, but a new joint material may be placed before the formation of the new coating, or the existing joint may be placed. It is also possible to apply a treatment such as painting to the surface of the material.

The coating material in the present invention contains a resin component, and the resin component is a (meth) acrylic acid alkyl ester (A) having an alkyl group having 3 or more carbon atoms as a resin component (hereinafter, “(A) component””. Also called). Such a resin component acts as a binder, and the component (A) can mainly impart resistance to water. In the present invention, the acrylic acid alkyl ester and the methacrylic acid alkyl ester are collectively referred to as a (meth) acrylic acid alkyl ester.

Examples of the form of the alkyl group in the component (A) include linear, branched, cyclic and the like. Examples of the component (A) include n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and t-butyl (meth) acrylate. N-pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, t-pentyl (meth) acrylate, 1-ethylpropyl (meth) acrylate, 2-methylbutyl (meth) acrylate , (Meta) 3-methylbutyl acrylate, (meth) n-hexyl acrylate, (meth) cyclohexyl acrylate, (meth) 2-ethylbutyl acrylate, (meth) 2-methylpentyl acrylate, (meth) acrylate 4-Methylpentyl, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, (meth) ) N-decyl acrylate, n-undecyl (meth) acrylate, n-lauryl (meth) acrylate and the like. These can be used alone or in combination of two or more. Among these, as the component (A), one having an alkyl group having 4 or more carbon atoms (more preferably 4 or more and 8 or less) is preferable.

The ratio of the component (A) in the resin constituents is 20% by weight or more, preferably 25 to 99% by weight, and more preferably 30 to 98% by weight. When the component (A) has the above ratio, resistance to water and the like can be enhanced, and effects such as discoloration, suppression of deterioration such as cracks, and maintenance of aesthetics can be obtained. In the present invention, "α to β" is synonymous with "α or more and β or less".

In the coating material of the present invention, as the component (A) in the resin constituent, a (meth) acrylic acid alkyl ester (a1) having an alkyl main chain having 3 or more carbon atoms (hereinafter, also referred to as “component (a1)”) is used. It is preferable to include it. As such a component (a1), the alkyl portion thereof is a linear or branched alkyl group (excluding a cyclic group), and the main chain (longest carbon straight chain) has 3 or more carbon atoms. Some can be used. If the resin component contains the component (a1), it is possible to further enhance the crack prevention property in addition to the resistance to water, and it is more preferable in terms of water impermeability, aesthetic retention, long life of the base material, and the like. ..

The component (a1) has an alkyl main chain having 3 or more carbon atoms in the alkyl moiety. The alkyl moiety of the component (a1) may have various side chains (for example, an alkyl group having a smaller number of carbon atoms than the alkyl main chain) as long as it has such an alkyl main chain. As the component (a1), among the above-mentioned components (A), those satisfying such conditions can be used. For example, n-propyl (meth) acrylic acid, isobutyl (meth) acrylic acid, and (meth) acrylic acid can be used. 1-Ethylpropyl, t-pentyl (meth) acrylate, neopentyl (meth) acrylate, n-butyl (meth) acrylate, 2-methylbutyl (meth) acrylate, isopentyl (meth) acrylate, (meth) acrylic 3-Methylbutyl acid, 2-ethylbutyl (meth) acrylate, n-pentyl (meth) acrylate, 2-methylpentyl (meth) acrylate, 4-methylpentyl (meth) acrylate, n- (meth) acrylate Hexil, 2-ethylhexyl (meth) acrylate, n-heptyl (meth) acrylate, isooctyl (meth) acrylate, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, (meth) acrylic acid Examples thereof include n-decyl, n-undecyl (meth) acrylate, and n-lauryl (meth) acrylate. These can be used alone or in combination of two or more. Among these, as the component (a1), one having an alkyl main chain having 4 or more carbon atoms (more preferably 4 or more and 8 or less) in the alkyl moiety is preferable.

Examples of the component (A) other than (a1) (hereinafter, also referred to as “component (a2)”) include isopropyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate and the like. Be done. These can be used alone or in combination of two or more.

The weight ratio of the component (a1) to the component (A) can be expressed as "r". This "r" is a value calculated by the following formula.
[Formula] r = {Weight of component (a1) in the resin component} / {Weight of component (A) in the resin component}

The r represented by the above formula is preferably 0.05 to 1.0, more preferably 0.1 to 0.9, still more preferably 0.15 to 0.8, and particularly preferably 0.2 to 0.7. Is.

As the resin constituent component, other monomers other than the component (A) (hereinafter, also referred to as “component (B)”) can be included. Examples of the component (B) include methyl (meth) acrylate, ethyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, or a carboxyl group-containing monomer, an amino group-containing monomer, and a pyridine-based monomer. , Hydroxyl group-containing monomer, nitrile group-containing monomer, amide group-containing monomer, epoxy group-containing monomer, carbonyl group-containing monomer, alkoxysilyl group-containing monomer, fluorine-containing monomer, aromatic monomer, ultraviolet-absorbing group-containing monomer, photostability group Examples include contained monomers. These can be used alone or in combination of two or more. The composition ratio of the component (B) is preferably 80% by weight or less (more preferably 1 to 75% by weight, more preferably 2 to 70% by weight) in the resin component. In the present invention, the monomer is a compound having a polymerizable unsaturated double bond.

In the present invention, the embodiment containing the ultraviolet-absorbing group-containing monomer and / or the light-stability group-containing monomer as the component (B) is preferable in terms of improving the effect of the present invention. The ultraviolet-absorbing group-containing monomer is a compound having a UV-absorbing group and a polymerizable unsaturated double bond, and examples of the UV-absorbing group include a benzophenone-based UV-absorbing group and a benzotriazole-based UV-absorbing group. Examples thereof include a triazine-based ultraviolet absorbing group and a salicylate-based ultraviolet absorbing group. The photostable group-containing monomer is a compound having a photostable group and a polymerizable unsaturated double bond, and examples of the photostable group include a piperidyl group and the like.

Such a resin component can be produced, for example, by polymerizing a component (A) (preferably containing the component (a1)) and a monomer group containing the component (B), if necessary. Examples of the form of the resin component include a water-soluble resin, a water-dispersible resin, a solvent-soluble resin, a solvent-free resin, a non-aqueous dispersion resin, and the like, or a composite thereof. Of these, the water-dispersible resin can be produced by a one-stage or multi-stage (two-stage or three-stage or more) emulsification polymerization method or the like. These may have a cross-linking reactivity, or may be either a one-component type, a two-component type, or the like.

The coating material in the present invention forms a coating film having visible light transmission. As a result, a transparent film can be formed, and it is possible to obtain a finish that makes use of the color tone (multicolor pattern, etc.) of the existing film surface. The visible light transmission may be such that the existing coating surface can be visually recognized.

The degree of visible light transmittance can be indicated by the visible light transmittance. The visible light transmittance is preferably 10% or more, more preferably 10 to 100%, still more preferably 15 to 90%. The visible light transmittance is a value measured by using a spectrophotometer for a film having a film thickness of 30 μm and a wavelength of 580 nm (the transmittance is 100% in the case of no film (air)). be.

The coating material in the present invention forms a film having a long-wave ultraviolet transmittance of 40% or less (preferably 0 to 30%) and a medium-wave ultraviolet transmittance of 20% or less (preferably 0 to 10%). .. In the present invention, when the long-wave ultraviolet ray transmittance and the medium-wave ultraviolet ray transmittance (hereinafter, also simply referred to as “ultraviolet ray transmittance”) are within the above ranges, the resistance to sunlight and the like can be enhanced, and discoloration, cracks and the like can be prevented. It is possible to obtain effects such as suppression of deterioration and maintenance of aesthetics. The long-wave ultraviolet transmittance is a value measured by using a spectrophotometer for a film having a film thickness of 30 μm and having a wavelength of 400 nm (the transmittance is 100% in the case of no film (air)). be. The medium-wave ultraviolet transmittance is a value measured by using a spectrophotometer for a film having a film thickness of 30 μm and having a wavelength of 300 nm (the transmittance is 100% in the case of no film (air)). ..

As a means for obtaining such an ultraviolet transmittance, for example,
(1) Use a coating material containing a resin component having an ultraviolet absorbing group.
(2) Use a covering material containing an ultraviolet absorber.
(3) Use a coating material containing UV-shielding powder.
And so on. These means may be adopted alone or in combination.

In the above (1), for example, a resin component containing an ultraviolet absorbing group-containing monomer may be used as the component (B). The ratio of the ultraviolet-absorbing group-containing monomer in the resin constituents is preferably 0.05 to 10% by weight, more preferably 0.1 to 5% by weight.

Examples of the ultraviolet absorber (excluding the compound having a polymerizable unsaturated double bond) in (2) above include a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, a triazine-based ultraviolet absorber, and a salicylate-based ultraviolet absorber. Examples include agents. Among these, examples of the benzophenone-based ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, and 2-hydroxy-4-n. -Octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 2,2'-dihydroxy -4-methoxybenzophenone, 2,2'-dihydroxy-4,4'dimethoxybenzophenone, 2,2', 4,4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-4- Examples thereof include methoxy-2'-carboxybenzophenone and 2-hydroxy-4-stearyloxybenzophenone. Examples of the benzotriazole-based ultraviolet absorber include 2- (2-hydroxy-5-t-butylphenyl) -2H-benzotriazole and 3- (2H-benzotriazole-2-yl) -5- (1,1). -Dimethylethyl) -4-hydroxyalkylester, 2- (2H-benzotriazole-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol, 2- (2H-benzotriazole-2) -Il) -6- (1-Methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol, methyl 3- (3- (2H-benzotriazole-2-yl) Examples thereof include reaction products of -5-t-butyl-4-hydroxyphenyl) propionate and polyethylene glycol. Examples of the triazine-based ultraviolet absorber include 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine-2-yl) -5-hydroxyphenyl derivative and 2- (2). , 4-Dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1,3,5-triazine and (2-ethylhexyl) -glycidate ester reaction product, 2,4-bis " 2-Hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3-5-triazine, etc. These can be used in one or more types. UV absorbers. The mixing ratio of the above is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the resin component.

As the ultraviolet shielding powder in (3) above, a powder having the ability to absorb and / or reflect ultraviolet rays can be used, and for example, barium sulfate, precipitated barium sulfate, calcium carbonate, magnesium carbonate, aluminum hydroxide, and water can be used. Magnesium oxide, zirconium oxide, magnesium oxide, boron nitride, bismuth oxychloride, zinc phosphate, mica, cold water stone, talc, diatomaceous clay, white clay, kaolin, clay, porcelain clay, barite powder, silica sand, silica stone powder, white carbon, metal powder , Organic resin powder and the like. These can be used in one type or two or more types. The average particle size of the ultraviolet shielding powder is preferably 1 nm to 20 μm. In the above (3), it is desirable to set the mixing ratio of the ultraviolet shielding powder within the range where the visible light transmission can be ensured.

In the above (3), the ultraviolet-shielding colored powder can also be used as the ultraviolet-shielding powder. Such UV-shielding colored powder exhibits colors such as yellow, orange, red, green, blue, purple, black, and white, and specifically, for example, yellow iron oxide and red oxidation. Iron, ultramarine, cobalt blue, cobalt green, carbon black, iron black, iron-manganese composite oxide, iron-copper-manganese composite oxide, iron-chromium-cobalt composite oxide, copper-chromium composite oxide, copper- Inorganic substances such as manganese-chromium composite oxide, alumina, titanium oxide, zinc oxide, etc., or azo-based, naphthol-based, pyrazolone-based, anthraquinone-based, perylene-based, quinacridone-based, disazo-based, isoindolinone-based, benzoimidazole. Examples thereof include organic substances such as system, phthalocyanine system, and quinophthalone system. These can be used in one type or two or more types.

In the present invention, by using such an ultraviolet shielding colored powder, it becomes easy to set the ultraviolet transmittance, particularly the long wave ultraviolet transmittance within the above range, and the effects such as deterioration suppression such as discoloration and cracking and maintenance of aesthetics are achieved. Can be increased. Further, by using one or more kinds of UV-shielding colored powders, it is possible to impart a desired color tone to the coating film while ensuring visible light transmission, and to improve the vividness of the existing coating film. It is also possible to increase it. In particular, the use of an inorganic UV-shielding colored powder is suitable in terms of improving such effects, and has an advantage in maintaining aesthetic appearance for a long period of time. The mixing ratio of the UV-shielding colored powder is preferably 0.01 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the resin component.

In addition to the above components, the coating material in the present invention is, if necessary, known additives such as aggregates, colored grains, dyes, matting agents, and thickeners, as long as the effects of the present invention are not significantly impaired. , Wetting agents, antifreeze agents, film-forming aids, preservatives, fungicides, algae-proofing agents, antibacterial agents, dispersants, defoamers, light stabilizers, antioxidants, adhesion-imparting agents, low pollution It may contain an agent, a hydrophilizing agent, a water repellent agent, a cross-linking agent, a curing accelerator, a catalyst and the like.

In the present invention, a new coating is formed by applying (painting) such a coating material. As the covering material, one kind or two or more kinds of covering materials satisfying the above conditions can be used. In the present invention, such a covering material can be overcoated. For example, one type of covering material may be applied a plurality of times, or two or more types of covering materials may be applied over and over again. When recoating, it is also possible to provide an appropriate interval to dry the film. Such a new coating film may be either glossy or matte (including 7-minute gloss, 5-minute gloss, 3-minute gloss, and the like).

The film thickness of the new coating formed by such a coating material is preferably 30 μm or more, more preferably 50 μm or more, still more preferably 60 μm or more, particularly preferably more than 65 μm, and most preferably 70 μm or more. When the lower limit of the film thickness is within the above range, the newly formed film is sufficiently resistant to sunlight and water, discoloration due to the existing film surface, deterioration suppression such as cracks, maintenance of aesthetic appearance for a long period of time, etc. It is suitable in that respect. The upper limit of the film thickness of the new coating film is not particularly limited, but is preferably 300 μm or less, more preferably 250 μm or less, and further preferably 200 μm or less. When the upper limit of the film thickness is within the above range, it is possible to obtain a finish utilizing the uneven pattern of the existing film surface. The film thickness in the present invention is a dry film thickness, and when one or more kinds of coating materials are applied repeatedly, it is the total dry film thickness after the application.

A known coating tool can be used for coating the covering material. As the painting tool, for example, a spray, a roller, a brush, or the like can be used. It is desirable to set the coating amount, the number of layers, etc. of the covering material so that the final film thickness is within the above range. The coating amount of the covering material is preferably 0.1 to 0.6 kg / m ² , more preferably 0.15 to 0.5 kg / m ² . The number of coats of the covering material is preferably 1 to 3 times. At the time of painting, the coating material can be appropriately diluted as needed. The drying after the coating material is applied may be carried out at room temperature (preferably 0 to 50 ° C., more preferably 5 to 45 ° C.), and may be heated if necessary.

Examples are shown below to clarify the features of the present invention.

The following materials (coating materials 1 to 7) were prepared as coating materials having visible light transmission.

-Coating material 1: Water-dispersible resin 1 {Cyclohexyl methacrylate, 2-ethylhexyl acrylate, methyl methacrylate, UV-absorbing group-containing monomer, photostability group-containing monomer, acrylic acid (weight ratio 20:52:23: 2: 2) 1) Emulsified polymer, resin constituent (A) component 72% by weight, r = 0.72}, thickener, film-forming aid, defoaming agent, UV-shielding powder (inorganic UV-shielding property) A mixture of colored powders, 0.4 parts by weight with respect to 100 parts by weight of the resin component), and a mixture of water. Long wave UV transmittance 18%, medium wave UV transmittance 4%.

-Coating material 2: Water-dispersible resin 2 {Cyclohexyl methacrylate, 2-ethylhexyl acrylate, methyl methacrylate, UV-absorbing group-containing monomer, photostable group-containing monomer, acrylic acid (weight ratio 25:30:40: 2: 2) 1) Emulsified polymer, resin constituent (A) component 55% by weight, r = 0.55}, thickener, film-forming aid, defoaming agent, UV-shielding powder (inorganic UV-shielding property) A mixture of colored powders, 0.4 parts by weight with respect to 100 parts by weight of the resin component), and a mixture of water. Long wave UV transmittance 18%, medium wave UV transmittance 3%.

-Coating material 3: Water-dispersible resin 3 {Cyclohexyl methacrylate, 2-ethylhexyl acrylate, methyl methacrylate, UV-absorbing group-containing monomer, photostable group-containing monomer, acrylic acid (weight ratio 32:18:45: 2: 2) 1) Emulsified polymer, resin constituent (A) component 50% by weight, r = 0.36}, thickener, film-forming aid, defoaming agent, UV-shielding powder (inorganic UV-shielding property) A mixture of colored powders, 0.4 parts by weight with respect to 100 parts by weight of the resin component), and a mixture of water. Long wave UV transmittance 18%, medium wave UV transmittance 4%.

-Coating material 4: Water-dispersible resin 4 {cyclohexyl methacrylate, 2-ethylhexyl acrylate, methyl methacrylate, ultraviolet-absorbing group-containing monomer, photostable group-containing monomer, acrylic acid (weight ratio 46: 4: 45: 2: 2) 1) Emulsified polymer, resin constituent (A) component 50% by weight, r = 0.08}, thickener, film-forming aid, defoaming agent, UV-shielding powder (inorganic UV-shielding property) A mixture of colored powders, 0.4 parts by weight with respect to 100 parts by weight of the resin component), and a mixture of water. Long wave UV transmittance 18%, medium wave UV transmittance 4%.

-Coating material 5: Water-dispersible resin 5 {cyclohexyl methacrylate, 2-ethylhexyl acrylate, methyl methacrylate, photostable group-containing monomer, acrylic acid (weight ratio 32:18:47: 2: 1) emulsified polymer, resin Among the constituents, (A) component 50% by weight, r = 0.36}, thickener, film-forming aid, defoaming agent, UV-shielding powder (mixture of inorganic UV-shielding colored powder, resin component 100) 0.4 parts by weight with respect to parts by weight), water, and a mixture of a triazine-based ultraviolet absorber (0.3 parts by weight with respect to 100 parts by weight of the resin component). Long wave UV transmittance 20%, medium wave UV transmittance 11%.

-Coating material 6: Water-dispersible resin 6 {Cyclohexyl methacrylate, 2-ethylhexyl acrylate, methyl methacrylate, UV-absorbing group-containing monomer, photostable group-containing monomer, acrylic acid (weight ratio 10: 8: 77: 2: 2) 1) Emulsified polymer, resin constituent (A) component 18% by weight, r = 0.44}, thickener, film-forming aid, defoaming agent, UV-shielding powder (inorganic UV-shielding property) A mixture of colored powders, 0.4 parts by weight with respect to 100 parts by weight of the resin component), and a mixture of water. Long wave UV transmittance 18%, medium wave UV transmittance 4%.

Coating material 7: Emulsified polymer of water-dispersible resin 7 {cyclohexyl methacrylate, 2-ethylhexyl acrylate, methyl methacrylate, acrylic acid (weight ratio 10: 8: 81: 1), 18 weights of component (A) in the resin constituents %, R = 0.44}, thickener, film-forming aid, defoaming agent, and a mixture of water. Long wave UV transmittance 56%, medium wave UV transmittance 53%.

[Test I]
(Example 1)
As an existing coating surface, a ceramic siding boat that has deteriorated due to outdoor exposure (has a tile-like uneven pattern on the surface, a black acrylic resin coating on the concave part, and a mixture of light brown and dark brown on the convex part). A color acrylic resin film, one having an acrylic silicon resin transparent film as a whole) was prepared. The entire surface of the existing coating surface was spray-coated with the coating material 1 so that the dry film thickness (referred to as "film thickness" in Table 1; the same applies hereinafter) was 75 μm (two coats) for 7 days. It was dried and cured. By the above method, a transparent new film was formed on the existing film surface, and a test piece was obtained in which the pattern on the existing film surface was visually recognized in a state of high vividness. All the painting and curing steps were performed under standard conditions (temperature 23 ° C., relative humidity 50%).

For the test piece obtained by the above method, an eye super UV tester (manufactured by Iwasaki Electric Co., Ltd.) was used as an accelerated weather resistance tester, and up to 45 cycles with 6 hours of light irradiation and 2 hours of dew condensation (8 hours in total) as one cycle. A accelerated test was performed. At this time, the appearance change (cracked state) of the surface of the test piece at the end of 25 cycles and the end of 45 cycles was observed, and the color difference before and after the promotion was measured. The change in appearance was evaluated on a four-point scale (excellent; A> B> C> D; inferior) with “A: no change” and “D: cracking progressed”. The color difference was evaluated as "A: color difference less than 1", "B: color difference 1 or more and less than 3", "C: color difference 3 or more and less than 10", and "D: color difference 10 or more". The test results are shown in Table 1.

(Example 2)
A similar test piece was prepared according to Example 1 except that the covering material 2 was used instead of the covering material 1, and the same test was performed. The test results are shown in Table 1.

(Example 3)
A similar test piece was prepared according to Example 1 except that the covering material 3 was used instead of the covering material 1, and the same test was performed. The test results are shown in Table 1.

(Example 4)
A similar test piece was prepared according to Example 1 except that the covering material 4 was used instead of the covering material 1, and the same test was performed. The test results are shown in Table 1.

(Example 5)
A similar test piece was prepared according to Example 1 except that the covering material 5 was used instead of the covering material 1, and the same test was performed. The test results are shown in Table 1.

(Example 6)
A similar test piece was prepared according to Example 1 and the same test was performed, except that the coating material 3 was used instead of the covering material 1 and the coating material 3 was coated so that the dry film thickness was 25 μm. rice field. The test results are shown in Table 1.

(Comparative Example 1)
A similar test piece was prepared according to Example 1 except that the covering material 6 was used instead of the covering material 1, and the same test was performed. The test results are shown in Table 1.

(Comparative Example 2)
A test body was prepared according to Example 1 except that the covering material 7 was used instead of the covering material 1, and the same test was performed. The test results are shown in Table 1.

[Test II]
The test specimens of Examples 1 to 6 were exposed to the outdoors for 3 months, and changes in appearance due to stains on the surface of the specimens were observed. A>B>C>D; inferior). The test results are shown in Table 1.

Claims (3)

It is a film forming method for forming a new film by applying a coating material having visible light transmission to an existing film surface provided on a base material.
The existing coated surface has an uneven pattern and / or a multicolored pattern.
The above-mentioned covering material is
It contains a resin component containing 20% by weight or more of (meth) acrylic acid alkyl ester (A) having an alkyl group having 3 or more carbon atoms in the resin constituent component, has a long-wave ultraviolet transmittance of 40% or less, and transmits medium-wave ultraviolet light. A film forming method characterized by forming a film having a ratio of 20% or less. The above-mentioned covering material is
The (meth) acrylic acid alkyl ester (A) having an alkyl group having 3 or more carbon atoms is characterized by containing a (meth) acrylic acid alkyl ester (a1) having an alkyl main chain having 3 or more carbon atoms. The film forming method according to claim 1. The film forming method according to claim 1 or 2, wherein the film thickness of the newly formed film is 30 μm or more.