Film formation method

Abstract

To provide a film forming method which is excellent in adhesion between a base material and a top coating material.SOLUTION: A film forming method that coats a primer coating material to a base material and then coats a top coating material thereto, is provided, the primer coating material contains a non-aqueous dispersion type resin (A), an aliphatic hydrocarbon-containing non-aqueous solvent (B), a metal chelate compound (C) and a polyisocyanate compound (D), as components, wherein the non-aqueous dispersion type resin (A) has a hydroxyl group.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a novel film-forming method.

Background Art

[0002] Conventionally, as base materials constituting buildings, civil engineering structures, etc., inorganic base materials such as concrete, mortar, slate boards, calcium silicate boards, siding boards, etc. have been widely used. When applying paint to these surfaces, in order to ensure adhesion and further prevent swelling, peeling, lifting, etc. of the film over time, usually, a primer is applied first, and then a topcoat is applied. Also, when repairing an old paint film surface, especially when repairing a paint film having functions such as high weather resistance and stain resistance provided on exterior building materials used for exterior wall surfaces, a primer is similarly applied first, and then a topcoat is applied.

[0003] Such primers are mainly classified into solvent-based primers and water-based primers, but solvent-based primers are often used from the viewpoint of adhesion. Among them, in recent years, in consideration of safety during painting, work hygiene, etc., or environmental problems, for example, weak solvent-type primers using aliphatic hydrocarbon solvents as main solvents as in Patent Document 1 have been widely used.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, as described above, in consideration of environmental problems, etc., topcoats are also often water-based topcoats or weak solvent-based topcoats. However, depending on the painting conditions of weak solvent-based primers and topcoats, etc., it may be difficult to ensure a high level of sufficient adhesion, and there was room for improvement.

[0006] The present invention has been made in view of such points, and an object thereof is to provide a film-forming method having excellent adhesion.

Means for Solving the Problems

[0007] In order to solve such problems, as a result of intensive studies, the present inventors have conceived of applying an undercoat material containing a non-aqueous dispersion resin and a specific compound as essential components to a substrate, and then applying a topcoat material, and have completed the present invention.

[0008] That is, the present invention has the following features. 1. A film-forming method in which an undercoat material is applied to a substrate and then a topcoat material is applied, wherein the undercoat material contains, as constituent components, a non-aqueous dispersion resin (A), an aliphatic hydrocarbon-containing non-aqueous solvent (B), a metal chelate compound (C), and a polyisocyanate compound (D), and the non-aqueous dispersion resin (A) has a hydroxyl group and the hydroxyl value is 1 to 150 mg KOH / g and the acid value is 0.1 to 30 mg KOH / g A film-forming method characterized by this. 2. The undercoat material further contains a coloring pigment ( E ) and / or a extender pigment ( F ), and the pigment volume concentration thereof is 30 to 80%, 1. The film-forming method according to the above. 3. The topcoat material is an aqueous topcoat material, 1. or 2. The film-forming method according to the above.

Effects of the Invention

[0009] The film-forming method of the present invention can exhibit excellent performance in terms of adhesion and the like.

Modes for Carrying Out the Invention

[0010] Hereinafter, modes for carrying out the present invention will be described.

[0011] The present invention is a film-forming method in which a topcoat is applied after applying a primer to a substrate, The primer contains, as constituent components, a non-aqueous dispersion resin (A), an aliphatic hydrocarbon-containing non-aqueous solvent (B), a metal chelate compound (C), and a polyisocyanate compound (D), and the non-aqueous dispersion resin (A) is characterized by having a hydroxyl group.

[0012] <Substrate> Examples of the substrate include concrete, mortar, slate board, calcium silicate board, ALC board, extruded board, slate tile, cement tile, new tile, porcelain tile, siding board, metal, glass, wood, plywood, etc.

[0013] Further, the above substrate may have various coating films (old coating films). Examples of such coating films include architectural weather-resistant topcoat paint (JIS K5658:2010), weather-resistant paint for steel structures (JIS K5659:2008), glossy synthetic resin emulsion paint (JIS K5660:2008), architectural fireproof paint (JIS K5661:1970), synthetic resin emulsion paint (JIS K5663:2008), road marking paint (JIS K5665:2011), multicolor pattern paint (JIS K5667:2003), synthetic resin emulsion pattern paint (JIS K5668:2010), acrylic resin-based non-aqueous dispersion paint (JIS K5670:2008), lead- and chromium-free rust preventive paint (JIS K5674:2008), roof high solar reflectance paint (JIS K5675:2011), building floor paint (JIS K5970:2008), architectural film waterproofing material (JIS A6021:2011), architectural finishing material (JIS A6909:2014), etc. In particular, the present invention can also be applied to fluororesin coating films, silicone resin coating films, etc.

[0014] <Primer> The primer of the present invention contains, as constituent components, a non-aqueous dispersion resin (A), an aliphatic hydrocarbon-containing non-aqueous solvent (B), a metal chelate compound (C), and a polyisocyanate compound (D).

[0015] The non-aqueous dispersion resin (A) (hereinafter also referred to as the “component (A)”) has both a resin part soluble in the aliphatic hydrocarbon-containing non-aqueous solvent (B) and a resin part insoluble therein, and is dispersed in the non-aqueous solvent (B) in the form of resin particles. The component (A) can be obtained, for example, by polymerizing various vinyl monomers in a conventional manner in the presence of a resin soluble in the non-aqueous solvent (B).

[0016] Examples of the vinyl monomer used include alkyl acrylates, hydroxyl group-containing monomers, and other monomers. The alkyl (meth)acrylate is a compound having a (meth)acryloyl group and an alkyl group. In the present invention, the alkyl acrylate and the alkyl methacrylate are collectively referred to as the alkyl (meth)acrylate. A monomer is a general term for compounds having a polymerizable unsaturated double bond.

[0017] Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 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, 3-methylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, 2-methylpentyl (meth)acrylate, 4-methylpentyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, n-lauryl (meth)acrylate and the like. These can be used alone or in combination of two or more.

[0018] Examples of the above-mentioned hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. These can be used alone or in combination of two or more.

[0019] Examples of the above-mentioned other monomers include aromatic monomers, carboxyl group-containing monomers, amino group-containing monomers, pyridine-based monomers, nitrile group-containing monomers, amide group-containing monomers, epoxy group-containing monomers, carbonyl group-containing monomers, alkoxysilyl group-containing monomers, fluorine-containing monomers, ultraviolet-absorbing group-containing monomers, and light-stabilizing group-containing monomers. These can be used alone or in combination of two or more.

[0020] The hydroxyl value (solid content) of component (A) is preferably 1 to 150 mgKOH / g (more preferably 5 to 100 mgKOH / g, still more preferably 10 to 80 mgKOH / g). By using component (A) having such a hydroxyl value, the curability (initial drying property) can be enhanced and the adhesion can be improved. In the present invention, "a to b" is synonymous with "a or more and b or less".

[0021] Furthermore, component (A) preferably has an acid value. Thereby, the effects of the present invention can be enhanced. The acid value (solid content) of component (A) is preferably 0.1 to 30 mgKOH / g (more preferably 0.3 to 20 mgKOH / g). Within such a range, the above effects can be further enhanced.

[0022] In order to set the acid value in the component (A) within the above range, as the above other monomer, for example, a carboxyl group-containing vinyl monomer or the like may be used. Examples of the carboxyl group-containing vinyl monomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid or its monoalkyl ester, itaconic acid or its monoalkyl ester, fumaric acid or its monoalkyl ester, ω-carboxy-polybutyrolactone mono (meth) acrylate, ω-carboxy-polyvalerolactone mono (meth) acrylate, ω-carboxy-polycaprolactone mono (meth) acrylate, ω-carboxy-polycaprylolactone mono (meth) acrylate, ω-carboxy-poly lauryllactone mono (meth) acrylate, (meth) acrylic acid dimer, (meth) acrylic acid trimer, (meth) acrylic acid tetramer, (meth) acrylic acid heptamer, (meth) acrylic acid hexamer and the like. These can be used alone or in combination of two or more.

[0023] The weight average molecular weight of the component (A) is preferably 10,000 to 500,000 (more preferably 20,000 to 300,000). The glass transition temperature of the component (A) is preferably -5°C to 70°C, more preferably 10°C to 60°C. The glass transition temperature is a value determined by Fox's calculation formula based on the vinyl monomer constituting the resin.

[0024] The above aliphatic hydrocarbon-containing non-aqueous solvent (B) (hereinafter also referred to as "component (B)") is a non-aqueous solvent with lower toxicity than toluene, xylene, etc., high safety in operation, and less impact on air pollution. Examples of the aliphatic hydrocarbon include n-hexane, n-pentane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane and the like. These can be used alone or in combination of two or more. In the present invention, an aliphatic hydrocarbon can also be introduced by using a mixed solvent such as mineral spirit. The aliphatic hydrocarbon is preferably contained in an amount of 5% by weight or more (more preferably 10 to 80% by weight) based on the total amount of the component (B).

[0025] (B) component may contain a solvent miscible with aliphatic hydrocarbons. Examples of such solvents include petroleum solvents such as petroleum ether, petroleum naphtha, and solvent naphtha, as well as ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, etc. Preferred solvents include, for example, petroleum solvents (aromatic hydrocarbon-containing petroleum mixed solvents) with a mixed aniline point or aniline point of 12 to 70 °C. The mixed aniline point or aniline point is a value measured by the method of JIS K2256:2013.

[0026] (B) The mixing ratio of the component is preferably 100 to 500 parts by weight, more preferably 120 to 400 parts by weight, based on 100 parts by weight of the solid content of the (A) component. Note that the (B) component also includes the solvent used as the medium for each component.

[0027] Examples of the metal in the above metal chelate compound (C) (hereinafter also referred to as the "(C) component") include various metals such as Al, Ti, Zr, Ca, Sn, Sr, Ba, Y, V, Nb, Ta, Cr, Mo, W, Fe, Co, Ni, Cu, Bi, and lanthanoid series. As the preparation method of the metal chelate compound, various known and commonly used methods can be adopted, such as the method of reacting alkoxides of the above various metals with a chelating agent.

[0028] Examples of the chelating agent include β-diketone compounds such as acetylacetone, dipyrovylmethane, trifluoroacetylacetone, hexafluoroacetylacetone, benzoylacetone, and dibenzoylmethane; β-ketoester compounds such as methyl acetoacetate, ethyl acetoacetate, allyl acetoacetate, benzyl acetoacetate, isopropyl acetoacetate, tert-butyl acetoacetate, isobutyl acetoacetate, 2-methoxyethyl acetoacetate, and methyl 3-keto-n-valerate; alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine.

[0029] In the present invention, as the component (C), at least one selected from an aluminum chelate compound, a titanium chelate compound, and a zirconium chelate compound is preferable. In particular, an aluminum chelate compound is preferable.

[0030] Examples of the aluminum chelate compound include tris(ethylacetoacetate)aluminum, tris(n-propylacetoacetate)aluminum, tris(isopropylacetoacetate)aluminum, tris(n-butylacetoacetate)aluminum, isopropoxybis(ethylacetoacetate)aluminum, diisopropoxyethylacetoacetatealuminum, tris(acetylacetonato)aluminum, tris(propionylacetonato)aluminum, diisopropoxypropionylacetonatoaluminum, acetylacetonato·bis(propionylacetonato)aluminum, monoethylacetoacetatebis(acetylacetonato)aluminum, tris(acetylacetonato)aluminum, and the like.

[0031] Examples of the titanium chelate compound include diisopropoxy·bis(ethylacetoacetate)titanate, diisopropoxy·bis(acetylacetonato)titanate, diisopropoxy·bis(acetylacetonato)titanate, and the like. Examples of the zirconium chelate compound include tetrakis(acetylacetonato)zirconium, tetrakis(n-propylacetoacetate)zirconium, tetrakis(acetylacetonato)zirconium, tetrakis(ethylacetoacetate)zirconium, and the like.

[0032] The above aluminum chelate compound, zirconium chelate compound, and titanium chelate compound can be used by appropriately combining one or more of them. The blending amount of component (C) is preferably 0.5 to 10 parts by weight (more preferably 1.0 to 8 parts by weight, even more preferably 1.5 to 8 parts by weight) based on 100 parts by weight of the solid content of component (A). By being in such a range, sufficient adhesion to the base material and the topcoat material can be obtained. In particular, it is effective in improving the adhesion to the topcoat material, and even when the topcoat material is an aqueous coating material, excellent adhesion effects can be exhibited.

[0033] It is preferable to further add the chelating auxiliary agent (C’) (hereinafter also referred to as “component (C’)”) to the undercoat material of the present invention. As component (C’), the above chelating agent can be used, and in particular, compounds such as acetoacetic acid esters and β-diketones are preferable. Thereby, sufficient storage stability can be obtained, and the adhesion can be further enhanced. It is preferable to add component (C’) to component (C) at a weight ratio of 1:1 to 5. In such a range, the above effects can be sufficiently obtained.

[0034] The polyisocyanate compound (D) (hereinafter also referred to as “component (D)”) has two or more isocyanate groups in one molecule and reacts with component (A). As component (D), those that can react with component (A) at room temperature are preferable. Here, the room temperature preferably refers to -10°C or higher and 50°C or lower, more preferably 5°C or higher and 40°C or lower.

[0035] As component (D), at least one diisocyanate selected from aliphatic diisocyanates and alicyclic diisocyanates, an alcohol component, and, if necessary, a polyol component, etc. are derivatized by alphanation, biuretization, dimerization (uretidonization), trimerization (isocyanuration), adductization, carbodiimidization reaction, etc., and mixtures thereof. These can be used singly or in combination of two or more.

[0036] An aliphatic diisocyanate is a compound having a saturated aliphatic group in the molecule. Examples include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane (also known as hexamethylene diisocyanate (HDI)), 1,6-diisocyanato-2,2,4-trimethylhexane, methyl 2,6-diisocyanatohexanoate (lysine diisocyanate), and the like. On the other hand, an alicyclic diisocyanate is a compound having a cycloaliphatic group in the molecule. Examples include 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane (isophorone diisocyanate), 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated xylylene diisocyanate), bis(4-isocyanatocyclohexyl)methane (hydrogenated diphenylmethane diisocyanate), 1,4-diisocyanatocyclohexane, and the like. Among these, HDI is most preferred because of its excellent weather resistance and flexibility.

[0037] Examples of the alcohol component include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, 2-pentanol, isoamyl alcohol, 1-hexanol, 2-hexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, 3,3,5-trimethyl-1-hexanol, tridecanol, pentadecanol, palmityl alcohol, stearyl alcohol, cyclopentanol, cyclohexanol, methylcyclohexanol, trimethylcyclohexanol, and the like. These can be used alone or in combination of two or more.

[0038] Examples of the polyol component include polyether polyol, polyester polyol, polyolefin-based polyol, and the like. In the present invention, polyether polyols such as polypropylene triol, polypropylene glycol, and polytetramethylene glycol are particularly preferred. These can be used alone or in combination of two or more.

[0039] The compounding quantity of component (D) is preferably 0.1 to 10 parts by weight (more preferably 0.2 to 5 parts by weight) with respect to 100 parts by weight of the solid content of component (A). By being in such a range, sufficient adhesiveness can be obtained. In particular, excellent effects can be exhibited in the adhesiveness to the substrate. Further, the molar ratio [NCO] / [OH] of the isocyanate group of component (D) and the hydroxyl group of component (A) is preferably 0.01 to 0.5 (more preferably 0.05 to 0.3). By being in such a range, excellent storage stability can be obtained and sufficient adhesiveness can be obtained.

[0040] Furthermore, as component (D), it is preferable to contain a polyisocyanate compound having an isocyanate group content of 10% by weight or more (more preferably 15% by weight or more and 30% by weight or less) in the solid content. Thereby, sufficient adhesiveness can be obtained and the water resistance is enhanced, which is effective in suppressing swelling of the film and the like. In the present invention, the isocyanate group content is defined as the content (% by weight) of the isocyanate group contained in the solid content of the polyisocyanate compound, and is a value obtained by back-titration with hydrochloric acid after neutralizing the isocyanate group with an excess amine.

[0041] The undercoat material of the present invention preferably contains a coloring pigment (E) and / or a extender pigment (F) in addition to the above components.

[0042] As the coloring pigment (E) (hereinafter also referred to as the "(E) component"), colored pigments, white pigments, black pigments, etc. can be used. Among these, colored pigments are pigments that exhibit colors such as yellow, orange, red, green, blue, purple, etc. Examples of such colored pigments include inorganic ones such as ferric oxide, hydrated ferric oxide, ultramarine, cobalt blue, cobalt green, etc., and organic ones such as azo-based, naphthol-based, pyrazolone-based, anthraquinone-based, perylene-based, quinacridone-based, disazo-based, isoindolinone-based, benzimidazole-based, phthalocyanine-based, quinophthalone-based, etc. On the other hand, white pigments are pigments that exhibit white, and examples include titanium oxide, zinc oxide, aluminum oxide, etc. Black pigments are pigments that exhibit black, and examples include inorganic ones such as iron black, iron-manganese composite oxide, iron-copper-manganese composite oxide, iron-chromium-cobalt composite oxide, copper-chromium composite oxide, copper-manganese-chromium composite oxide, etc., and others such as carbon black. These can be used alone or in combination of two or more. Also, those with some treatment on their surface may be used. The average particle diameter of the (E) component is preferably 1 μm or less, more preferably 0.01 - 0.9 μm.

[0043] The blending amount of the (E) component is preferably 5 - 100 parts by weight (more preferably 10 - 80 parts by weight) with respect to 100 parts by weight of the solid content of the (A) component. If the (E) component is in such a ratio, the undercoat material can be colored to a desired color, and hiding power, aesthetic appearance, etc. can be enhanced.

[0044] The extender pigment (F) (hereinafter also referred to as the "(F) component") can be used, for example, for the purposes of solid content adjustment, viscosity adjustment, gloss adjustment (such as gloss reduction), or improvement of storage stability and pigment miscibility. Examples of the component (F) include heavy calcium carbonate, light calcium carbonate, kaolin, clay, pottery clay, china clay, diatomaceous earth, hydrated fine silica, talc, barite powder, barium sulfate, precipitated barium sulfate, barium carbonate, magnesium carbonate, silica powder, aluminum hydroxide, etc. These can be used alone or in combination of two or more. The average particle diameter of the component (F) is preferably 0.1 to 100 μm (preferably 1 to 80 μm).

[0045] The blending amount of the component (F) is preferably 10 to 500 parts by weight (more preferably 20 to 300 parts by weight) with respect to 100 parts by weight of the solid content of the component (A).

[0046] In the present invention, the above-mentioned component (E) and / or the above-mentioned component (F) are blended so that the pigment volume concentration in the formed coating film is preferably 30 to 80% (more preferably 35 to 65%). With such a pigment volume concentration, a coating film having sufficient adhesion can be formed.

[0047] In addition to the above-mentioned components, the undercoat material of the present invention may contain various components to the extent that it does not affect the effects of the present invention. Examples of such components include plasticizers, preservatives, fungicides, algicides, defoamers, leveling agents, pigment dispersants, thickeners, anti-skinning agents, dehydrating agents, matting agents, ultraviolet absorbers, light stabilizers, antioxidants, catalysts, etc. Further, it may contain a resin component other than the component (A). The undercoat material of the present invention can be produced by uniformly stirring and mixing the above-mentioned components (A) to (D) (preferably components (A) to (F)) and such various components as needed by a conventional method. Further, it is desirable to use the undercoat material of the present invention in the form of a one-component type.

[0048] In the coating of the undercoat material of the present invention, for example, various methods such as brush coating, roller coating, spray coating, etc. can be adopted. When coating in a factory, it can also be coated using a roll coater, a flow coater, etc.

[0049] The coating amount of the undercoat material is preferably 0.1 to 0.6 kg / m2 (more preferably 0.2 to 0.5 kg / m 2 ). Also, the number of coating applications may be appropriately set according to the surface condition of the substrate etc., but is preferably 1 to 2 times. The drying time is preferably 1 hour or more and within 1 week. Also, the drying temperature is preferably -10°C or more and 50°C or less (more preferably -5°C or more and 40°C or less).

[0050] <Topcoat material> In the present invention, after applying and drying the above-mentioned undercoat material, by applying the topcoat material, it is possible to protect the finished surface or improve the aesthetics etc.

[0051] As the resin component in the topcoat material, various resins can be used. Examples of the type of resin include vinyl acetate resin, polyester resin, alkyd resin, vinyl chloride resin, epoxy resin, acrylic resin, urethane resin, acrylic silicone resin, fluororesin, etc., or composite resins thereof etc. Among these, one or more selected from acrylic resin, urethane resin, acrylic silicone resin, fluororesin, etc. are preferable. Also, examples of the form of such a resin component include water-soluble resin, water-dispersible resin (resin emulsion), solvent-soluble resin, solventless resin, non-aqueous dispersion resin, powder resin, etc. Among these, one or more selected from aqueous topcoat materials such as water-soluble resin and water-dispersible resin, and solvent-based (preferably weak solvent-based) topcoat materials such as solvent-soluble resin and non-aqueous dispersion resin are preferable. In the present invention, by using the above-mentioned undercoat material, sufficient adhesion can be ensured even for an aqueous topcoat material.

[0052] Such topcoats may contain various components other than the above components as long as the effects of the present invention are not significantly impaired. Such components include, for example, thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreeze agents, pH adjusters, coloring pigments, extender pigments, aggregates, preservatives, fungicides, algicides, antibacterial agents, dispersants, defoamers, adsorbents, fibers, crosslinking agents, ultraviolet absorbers, light stabilizers, antioxidants, low-pollution agents, hydrophilizing agents, water-repellent agents, catalysts, solvents, water, and the like. The topcoat of the present invention can be produced by uniformly mixing the above resin component and, if necessary, the various components described above by a conventional method. The form of the topcoat can be, for example, a one-component type, a two-component type, or a multi-component type of three or more components.

[0053] In the painting of the topcoat, known painting tools can be used. As the painting tools, for example, sprayers, rollers, brushes, etc. can be used. The coating amount of the topcoat may be appropriately set according to the surface shape of the existing wall surface, the type of the topcoat, the type of the painting tool, etc., but is preferably 0.1 to 0.5 kg / m 2 (More preferably 0.2 to 0.4 kg / m 2 )). At the time of painting, the topcoat can be appropriately diluted if necessary.

Examples

[0054] Examples are shown below to make the features of the present invention clearer. <Manufacture of the primer> According to the formulation shown in Table 1, each component was mixed and stirred by a conventional method to obtain a primer.

[0055] In addition, the following raw materials were used. (A) Non-aqueous dispersion resin ·(A1): Non-aqueous dispersion acrylic polyol (alkyl acrylate·acrylic ester methacrylate·hydroxyalkyl methacrylate copolymer dispersion [hydroxyl value 40 mgKOH / g, acid value 2 mgKOH / g, weight average molecular weight 70000, solid content 50% by weight, medium: mineral spirit (aniline point 42°C) ·(A2): Non-aqueous dispersion type acrylic polyol (alkyl acrylate·acrylic methacrylate·alkyl methacrylate copolymer dispersion [hydroxyl value 0 mgKOH / g, acid value 2 mgKOH / g, weight average molecular weight 70,000, solid content 50 wt%, medium: mineral spirit (aniline point 42°C)] (B) Aliphatic hydrocarbon-containing non-aqueous solvent · Mineral spirit (C) Metal chelate compound · Aluminum chelate compound [ethyl acetoacetate aluminum diisopropylate (Al content: 9.8 wt%)] (C’) Chelating auxiliary agent · Acetylacetone (D) Polyisocyanate compound ·(D1): Hexamethylene diisocyanate derivative solution [solid content: 100 wt%, isocyanate group content: 21 wt%] ·(D2): Hexamethylene diisocyanate derivative solution [solid content: 100 wt%, isocyanate group content: 12 wt%] (E) Coloring pigment · Rutile type titanium oxide (average particle diameter: 0.3 μm, specific gravity: 4.2) (F) Extender pigment · Calcium carbonate (average particle diameter: 10 - 20 μm, specific gravity 2.7) (Additive) · Defoamer, thickener, dispersant, etc.

[0056]

Table 1

[0057] <Topcoat> · Topcoat 1 (acrylic resin emulsion paint) · Topcoat 2 (acrylic silicone resin emulsion paint)

[0058] (Examples 1 - 11, Comparative Examples 1 - 4) The undercoats and topcoats shown in Table 2 were used, and the following evaluations were carried out. The results are shown in Table 2. <Adhesion Evaluation 1> □ On a siding board with an inorganic clear coating film formed as an existing coating film, an undercoat material was applied at an application rate of 0.30 kg / m 2 and the test specimen [I] was prepared by drying it for 24 hours under standard conditions (temperature 23°C, relative humidity 50%). □ The prepared test specimen [I] was evaluated for adhesion by the cross-cut tape method according to JIS K 5600-5-6. The evaluation criteria are as follows. AA: The area of the defective part is less than 5% A: The area of the defective part is 5% or more and less than 10% AB: The area of the defective part is 10% or more and less than 25% B: The area of the defective part is 25% or more and less than 40% C: The area of the defective part is 40% or more and less than 55% D: The area of the defective part is 55% or more

[0059] <Adhesion Evaluation 2> □ On a siding board with an inorganic clear coating film formed as an existing coating film, an undercoat material was applied at an application rate of 0.30 kg / m 2 and dried for 24 hours under standard conditions (temperature 23°C, relative humidity 50%). Then, a topcoat material was applied at an application rate of 0.20 kg / m 2 and the test specimen [II] was prepared by drying it for 24 hours in an environment at 50°C. □ The prepared test specimen [II] was evaluated in the same manner as in Adhesion Evaluation 1.

[0060] <Adhesion Evaluation 3> The prepared test specimen [II] was immersed in water at 20°C for 3 days, then the specimen was taken out and dried (23°C, 3 hours), and the coating film state was visually observed for swelling, peeling, whitening, etc. and evaluated. The evaluation criteria were a four-level evaluation (A > B > C > D) where those with almost no abnormality were rated as "A" and those with abnormalities were rated as "D".

[0061] In Examples 1 to 10, good adhesion was obtained. In particular, in Examples 3 to 7, excellent adhesion to both the substrate and the aqueous topcoat could be obtained.

[0062]

Table 2

Claims

1. A film-forming method in which a topcoat is applied after applying a primer to a substrate, wherein the primer contains, as constituent components, a non-aqueous dispersion resin (A), an aliphatic hydrocarbon-containing non-aqueous solvent (B), a metal chelate compound (C), and a polyisocyanate compound (D), and the non-aqueous dispersion resin (A) has a hydroxyl group, a hydroxyl value of 1 to 150 mgKOH / g, and an acid value of 0.1 to 30 mgKOH / g.

2. The film-forming method according to claim 1, wherein the primer further contains a coloring pigment (E) and / or a extender pigment (F), and the pigment volume concentration thereof is 30 to 80%.

3. The film-forming method according to claim 1 or claim 2, wherein the topcoat is an aqueous topcoat.

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