Coating formation method

Abstract

To improve adhesion, lifting resistance, etc. of a coating material including an oxidative curing resin.SOLUTION: A film formation method includes: manufacturing a coating material by uniformly mixing an oxidative curing resin (A1) which is a soluble resin soluble in an aliphatic hydrocarbon-containing solvent (C) and whose weight average molecular weight is 2000-20000, an oxidative curing resin (A2) which is a soluble resin soluble in the aliphatic hydrocarbon-containing solvent (C) and whose weight average molecular weight is 28000-300000, a metal dryer (B), and the aliphatic hydrocarbon-containing solvent (C); and applying an epoxy resin undercoat material to a base material, followed by applying the coating material thereto.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a novel coating material and a method for forming a coating. [Background technology]

[0002] Traditionally, in buildings, civil engineering structures, and other structures, various coating materials (primers, topcoats, etc.) have been layered to form a protective film, with the aim of adding functionality to the base material, as well as improving its protection and aesthetic appeal. In recent years, however, in the field of such coating materials, there has been a growing movement to reduce the use of aromatic hydrocarbon-containing solvents such as toluene and xylene, considering safety during painting, occupational hygiene, and the impact on air pollution. To address this trend, various environmentally friendly coating materials using aliphatic hydrocarbon-containing solvents have been proposed.

[0003] Furthermore, coatings using oxidative-curing resins are known as environmentally friendly coatings (e.g., Patent Document 1). Patent Document 1 describes a one-component crosslinking (curing type) coating that generates a crosslinking reaction through the oxidation of reactive double bonds contained in unsaturated fatty acids. Coatings containing such oxidative-curing resins are widely used as topcoats because they have excellent gloss and workability. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-262055 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, when using such environmentally friendly coatings as topcoats, lifting of the coating material may occur depending on the type of undercoat used. Furthermore, glossiness may also be inferior in some cases.

[0006] This invention has been made in view of the above points, and aims to improve the lifting resistance, gloss, etc., of coating materials containing oxidation-curing resins. [Means for solving the problem]

[0007] To solve these problems, the inventors, after diligent research, conceived of a coating material that uses a specific oxidation-curing resin as an essential component, and thus completed the present invention.

[0008] In other words, the present invention has the following features. 1. A soluble resin (A1) that is soluble in an aliphatic hydrocarbon-containing solvent (C) and has a weight-average molecular weight of 2,000 to 20,000, an oxidative-curing resin (A2) that is soluble in an aliphatic hydrocarbon-containing solvent (C) and has a weight-average molecular weight of 28,000 to 300,000, a metal dryer (B), and an aliphatic hydrocarbon-containing solvent (C) are uniformly mixed. The mixing ratio of the above-mentioned oxidative-curing resin (A1) and the above-mentioned oxidative-curing resin (A2) is 99:1 to 50:50 in terms of solid content by weight. We manufacture covering materials, A method for forming a coating, characterized by applying an epoxy resin primer to a substrate, and then applying the coating material described above. [Effects of the Invention]

[0009] The coating material of the present invention can form a coating with excellent lifting resistance and other properties. Furthermore, it can also provide advantageous effects in terms of finish, such as gloss. [Modes for carrying out the invention]

[0010] The following describes embodiments for carrying out the present invention.

[0011] <Coating material> The coating material of the present invention comprises an oxidative curing resin (A), a metal dryer (B), and an aliphatic hydrocarbon-containing solvent (C), and is a so-called weak solvent type coating material.

[0012] The oxidative curing resin (A) of the present invention (hereinafter also referred to as "component (A)") is characterized by being cured and dried by air oxidation due to oxidatively polymerizable double bonds (oxidative polymerizable groups), and being soluble in an aliphatic hydrocarbon-containing non-aqueous solvent (C). Such component (A) is not particularly limited as long as it has an oxidative polymerizable group, and can be obtained, for example, by polymerizing various vinyl monomers in the above-mentioned aliphatic hydrocarbon-containing non-aqueous solvent (C) by conventional methods.

[0013] Specifically, the following resins can be used. 1) A resin obtained by copolymerizing a vinyl monomer having an oxidative polymerizable group with another vinyl monomer copolymerizable with this monomer. 2) A resin obtained by copolymerizing an epoxy group-containing vinyl monomer with another vinyl monomer copolymerizable with this monomer, and then adding an unsaturated fatty acid to the epoxy group-containing vinyl monomer. 3) A resin obtained by copolymerizing and / or graft polymerizing a vinyl monomer having an oxidative polymerizable group, and / or another vinyl monomer copolymerizable with this monomer, in an alkyd resin. In the present invention, the resins described in 1) to 3) above can be mixed and used.

[0014] Examples of vinyl monomers having oxidative polymerizable groups in 1) and 3) above include vinyl monomers obtained by adding unsaturated fatty acids to epoxy group-containing vinyl monomers. These vinyl monomers are obtained by the reaction of epoxy groups with carboxyl groups in unsaturated fatty acids. The resin in 2) above is obtained by the addition reaction of unsaturated fatty acids to epoxy groups in the resin. When reacting epoxy groups with unsaturated fatty acids, catalysts such as tertiary amines or quaternary ammonium salts can be used.

[0015] Specific examples of the epoxy group-containing vinyl monomer include glycidyl (meth)acrylate, β-methyl glycidyl (meth)acrylate, 3,4-oxycyclohexylpropyl (meth)acrylate, allyl glycidyl ether, and the like.

[0016] Examples of the unsaturated fatty acid include linseed oil fatty acid, tung oil fatty acid, fish oil fatty acid, dehydrated castor oil fatty acid, soybean oil fatty acid, sesame oil fatty acid, poppy seed oil fatty acid, perilla oil fatty acid, safflower oil fatty acid, hemp seed oil fatty acid, grape seed oil fatty acid, tall oil fatty acid, sunflower oil fatty acid, cottonseed oil fatty acid, corn oil fatty acid, walnut oil fatty acid, and the like.

[0017] As the vinyl monomer having an oxidation-polymerizable group in the above 1) and 3), for example, a dicyclopentadiene oxyalkyl group-containing vinyl monomer such as dicyclopentadiene oxyalkyl (meth)acrylate, and an allyl group-containing vinyl monomer such as allyl (meth)acrylate can also be used.

[0018] The content of the unsaturated fatty acid in the above 1) to 3) is preferably 1 to 20% by weight (more preferably 2 to 15% by weight) as a solid content in the component (A). By containing the unsaturated fatty acid in the component (A) within such a range, the coating material of the present invention can form a film excellent in adhesion, anti-lifting property, glossiness, and the like. In the present invention, "α to β" has the same meaning as "α or more and β or less".

[0019] As the alkyd resin in 3) above, a resin obtained by polycondensing a polyhydric alcohol and a polyhydric carboxylic acid and modifying it with a drying oil, unsaturated fatty acid, etc., can be used. Examples of polyhydric alcohols include ethylene glycol, glycerin, and pentaerythritol, and examples of polyhydric carboxylic acids include phthalic anhydride and maleic anhydride. Examples of drying oils include linseed oil, tung oil, safflower oil, etc. The alkyd resin content is preferably 0 to 20% by weight (more preferably 2 to 15% by weight) as solid content in component (A). By containing alkyd resin in component (A) within this range, the coating material of the present invention can form a film with excellent adhesion, lifting resistance, gloss, etc.

[0020] Other vinyl monomers mentioned in 1) to 3) above include, for example, alkyl (meth)acrylates, aromatic monomers, and other vinyl monomers.

[0021] Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, and cyclohexyl (meth)acrylate. These can be used individually or in combination of two or more.

[0022] Examples of aromatic monomers include styrene, 2-methylstyrene, vinyltoluene, t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene, and divinylbenzene. These can be used individually or in combination of two or more.

[0023] Other vinyl monomers that can be used include, for example, hydroxyl group-containing vinyl monomers, carboxyl group-containing vinyl monomers, and amino group-containing vinyl monomers. Examples of hydroxyl group-containing vinyl monomers include 2-hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate. These can be used individually or in combination of two or more. Examples of carboxyl group-containing vinyl monomers 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, etc. These can be used individually or in combination of two or more. Examples of amino group-containing vinyl monomers include N-methylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylaminoethyl vinyl ether, N-(2-dimethylaminoethyl)acrylamide, and N-(2-dimethylaminoethyl)methacrylamide. These can be used individually or in combination of two or more.

[0024] Component (A) of the present invention preferably includes, as other vinyl monomers, a copolymer of at least an alkyl (meth)acrylate, or a copolymer of an alkyl (meth)acrylate and an aromatic monomer.

[0025] In this invention, as component (A), a component having an acid value of preferably 0.1 to 20 mg KOH / g (more preferably 0.5 to 10 mg KOH / g) can be used. Such an acid value of component (A) contributes to improved adhesion with the undercoat material. Furthermore, if the acid value of component (A) is within the above range, adhesion after long-term storage is also ensured. The acid value is expressed by the number of mg of potassium hydroxide equivalent to the acid groups contained in 1 g of the solid content of component (A). To set the acid value of component (A) within the above range, for example, the carboxyl group-containing vinyl monomer can be used as the vinyl monomer during the polymerization of component (A).

[0026] The present invention is characterized by containing at least two components (A) with different weight-average molecular weights. By including such components (A), excellent adhesion, lifting resistance, and other properties can be achieved, and superior effects can be observed in finish properties such as gloss. The weight-average molecular weight of component (A) is preferably 2,000 to 300,000 (more preferably 5,000 to 250,000). The weight-average molecular weight is measured, for example, by gel permeation chromatography (GPC).

[0027] In the present invention, it is preferable that component (A) contains an oxidative curing resin (A1) (hereinafter also referred to as "component (A1)") having a weight-average molecular weight of 25,000 or less (more preferably 2,000 to 20,000). This provides excellent improvements in adhesion, lifting resistance, gloss, and other finish properties. In the present invention, component (A) may contain two or more of the above-mentioned component (A1), but it is particularly preferable to contain the above-mentioned component (A1) and an oxidative curing resin (A2) (hereinafter also referred to as "component (A2)") having a weight-average molecular weight of more than 25,000 (more preferably 28,000 to 300,000). By including such components (A1) and (A2), even better improvements in adhesion, lifting resistance, gloss, and other finish properties can be obtained.

[0028] The mixing ratio of component (A1) and component (A2) is preferably a solid weight ratio (A1):(A2) = 100:0 to 50:50 (more preferably 99:1 to 60:40). In this case, the above effect can be further enhanced.

[0029] The glass transition temperature of component (A) is preferably 0°C to 80°C (more preferably 10°C to 60°C). If the glass transition temperature is within this range, the film properties such as adhesion and durability can be improved. The glass transition temperature is a value determined by Fox's formula based on the vinyl monomers constituting the resin.

[0030] The metal dryer (B) in the coating material of the present invention (hereinafter also referred to as "component (B)") is a component that acts as a curing catalyst for component (A) above. As component (B), known organometallic compounds such as cobalt-based, manganese-based, zirconium-based, tin-based, lead-based, zinc-based, copper-based, iron-based, calcium-based, and barium-based compounds can be used. Specifically, examples include cobalt octoate, cobalt naphthenate, manganese octoate, manganese naphthenate, zirconium octoate, zirconium naphthenate, tin octoate, lead naphthenate, zinc naphthenate, copper naphthenate, iron naphthenate, calcium octoate, calcium naphthenate, barium octoate, and barium naphthenate. These can be used one or more of each.

[0031] The mixing ratio of component (B) is preferably 0.001 to 10 parts by weight (more preferably 0.01 to 5 parts by weight) of metal content per 100 parts by weight of solid content of component (A).

[0032] The aliphatic hydrocarbon-containing solvent (C) of the present invention (hereinafter also referred to as "component (C)") is a non-aqueous solvent that is less toxic, safer to use in the workplace, and has less impact on air pollution compared to aromatic hydrocarbon-containing solvents. Examples of component (C) include n-hexane, n-pentane, n-octane, n-nonane, n-decane, n-undecane, and n-dodecane. In addition, in the present invention, terpine oil and mineral spirits can also be used as the aliphatic hydrocarbon-containing solvent.

[0033] In addition to the components described above, the coating material of the present invention may also contain various other components to the extent that they do not affect the effects of the present invention. Examples of such components include coloring pigments, extender pigments, thickeners, film-forming aids, leveling agents, plasticizers, antifreeze agents, pH adjusters, diluents, preservatives, antifungal agents, antialgal agents, antibacterial agents, dispersants, defoaming agents, ultraviolet absorbers, antioxidants, light stabilizers, fibers, catalysts, crosslinking agents, and the like.

[0034] The coating material of the present invention can be manufactured by uniformly stirring and mixing the above-mentioned components using conventional methods. The coating material of the present invention can be used in a one-component form.

[0035] <Film formation method> The coating material of the present invention can be applied mainly to protect the structure and improve the aesthetics of buildings, civil engineering structures, etc., and is suitable, for example, as a topcoat coating material applied to a substrate via an undercoat coating. In the present invention, for example, a coating can be formed by applying an undercoat to a substrate and then applying the coating material of the present invention.

[0036] The base material is primarily used for protecting the structure of buildings, civil engineering structures, etc., and can be used for surface finishing of various base materials such as concrete, mortar, porcelain tiles, siding boards, extruded boards, color steel plates, copper plates, aluminum plates, titanium plates, stainless steel plates, galvanized steel plates, metals, glass, plastics, wood, and plywood. These base materials may have a pre-existing coating on their surface. In the film-forming method of the present invention, the undercoat material can be applied directly to the base material, but it is also possible to apply some kind of surface treatment to the base material beforehand (such as undercoating with sealers, primers, surfacers, fillers, putties, etc.).

[0037] Various known or commercially available primers can be used as undercoats. Specifically, examples of primers include acrylic resin primers, epoxy resin primers, urethane resin primers, and chlorinated rubber primers. Such primers may be clear or colored. They may also contain rust-preventive pigments such as phosphate, molybdate, or zinc-based pigments.

[0038] In particular, the present invention can be used in conjunction with epoxy resin primers to achieve remarkable results. For example, when a coating material containing an oxidation-curing resin and a metal dryer is applied over an epoxy resin primer, the coating material may dissolve or lift (lift) the coating film. However, by using the coating material of the present invention, the occurrence of such problems can be suppressed, and excellent adhesion, lifting resistance, and finish quality can be improved.

[0039] As an epoxy resin primer, one containing one or more epoxy resins as a binder component can be used. Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, alkyl ether type epoxy resin, hydrogenated bisphenol A type epoxy resin, or modified versions thereof. The epoxy resin primer may be in one-component or two-component form. In the case of a two-component type, a hardening agent containing an amine compound or the like can be used.

[0040] The primer material contains the above-mentioned binder component as an essential component, and various other components may be added to an extent that does not affect the effects of the present invention. Examples of such components include coloring pigments, extender pigments, rust inhibitors, thickeners, film-forming aids, leveling agents, plasticizers, antifreeze agents, pH adjusters, diluents, preservatives, antifungal agents, antialgal agents, antibacterial agents, dispersants, defoaming agents, ultraviolet absorbers, antioxidants, light stabilizers, fibers, catalysts, crosslinking agents, and the like.

[0041] Such primers can be applied using various methods, such as brush painting, roller painting, spray painting, roll coater, and flow coater. The application rate depends on the form of the primer, but is preferably 0.05 to 3 kg / m². 2 (more preferably 0.05~2kg / m 2 )

[0042] Various methods can be used to apply the coating material of the present invention, such as brush coating, roller coating, spray coating, roll coater, and flow coater. In this case, the coating material of the present invention may be appropriately diluted with an aliphatic hydrocarbon solvent. The application amount is preferably 0.1 to 0.5 kg / m². 2 To that extent. Furthermore, the coating material may be finished with a single layer, or it may be finished by laminating two or more layers. [Examples]

[0043] The following examples illustrate the features of the present invention.

[0044] (Coating material 1~10) Coating materials 1 to 10 were manufactured by mixing the raw materials listed below according to the formulations shown in Table 1 using a conventional method.

[0045] The following raw materials were used for each topcoat material. (A) Oxidation-curing resin (A-1) Dehydrated castor oil fatty acid modified product of styrene-isobutyl methacrylate-2-ethylhexyl acrylate-glycidyl methacrylate copolymer [Weight-average molecular weight: 12,000, Solids content: 50% by weight (Unsaturated fatty acid content in solids: 10% by weight), Acid value: 1.5 mg KOH / g, Solvent: Mineral spirit solution] (A-2) Styrene-isobutyl methacrylate-2-ethylhexyl acrylate-glycidyl methacrylate copolymer, modified soybean oil fatty acid [Weight-average molecular weight: 25,000, Solids content: 50% by weight (Unsaturated fatty acid content in solids: 10% by weight), Acid value: 1.5 mg KOH / g, Solvent: Mineral spirit solution] (A-3) Styrene-isobutyl methacrylate-2-ethylhexyl acrylate-glycidyl methacrylate copolymer, modified soybean oil fatty acid [Weight-average molecular weight: 40,000, Solids content: 50% by weight (Unsaturated fatty acid content in solids: 10% by weight), Acid value: 1.5 mg KOH / g, Solvent: Mineral spirit solution] (A-4) A copolymer of monomer, styrene, isobutyl methacrylate, 2-ethylhexyl acrylate, dimethylaminoethyl methacrylate, and alkyd resin obtained by adding glycidyl methacrylate and soybean oil fatty acid [Weight-average molecular weight: 45,000, Solids content: 50% by weight (Unsaturated fatty acid content in solids: 8% by weight, Alkyd resin content: 10% by weight), Acid value: 1.5 mg KOH / g, Solvent: Mineral spirit solution] (B) Metal hair dryer • Mixture of cobalt naphthenate and zirconium naphthenate (mineral spirit solution, Co 0.3% by weight, Zr 3% by weight) (C) Non-aqueous solvent containing aliphatic hydrocarbons • A mixture of mineral spirits and a petroleum-based solvent containing aromatic hydrocarbons (aliphatic hydrocarbon content: 65% by weight) (D) Other • Coloring pigment: Titanium dioxide • Additives: Antifoaming agents, dispersants, UV absorbers, light stabilizers, etc.

[0046] (Examples 1-8, Comparative Examples 1-2) <Preparation of test specimen [I]> For a 200 x 150 mm tin plate, apply a two-component reactive curing epoxy resin primer [main component: phenol novolac type epoxy resin with epoxy equivalent of 1350 g / eq, curing agent component: polyamideamine with activated hydrogen equivalent of 360 g / eq] at a rate of 0.1 kg / m². 2 It was applied with a brush and allowed to dry and cure for 24 hours under standard conditions. Next, the coating material obtained by the above method is applied using a roller at a rate of 0.12 kg / m². 2 The coating was applied and allowed to dry and cure for 16 hours under standard conditions to form a film, after which cross-cuts were made with a cutter. Next, the same coating material was applied using a roller at a rate of 0.12 kg / m². 2 Test specimen [I] was prepared by applying the material and curing it under standard conditions for 24 hours.

[0047] <Lifting resistance evaluation> The surface condition of test specimen [I] was observed and evaluated on the following five-point scale. The results are shown in Table 1. AA: No abnormality was observed. A: Almost no abnormality was observed (there was a slight shrinkage). B: A slight lifting phenomenon (there was a slight shrinkage) was observed at the cut part. C: A lifting phenomenon (overall shrinkage) was observed. D: A dissolution phenomenon was observed.

[0048] <Preparation of Specimen [II]> For a 200×150 mm iron plate, a two-component reaction-curing epoxy resin primer (same as above) was applied by brush at an application rate of 0.1 kg / m 2 and dried and cured for 24 hours under standard conditions. Next, the coating material obtained by the above method was applied using a roller at an application rate of 0.12 kg / m 2 and after drying and curing for 16 hours under standard conditions, the same coating material was applied using a roller at an application rate of 0.12 kg / m 2 and cured for 24 hours under standard conditions. The resulting specimen was designated as Specimen [II], and the following evaluations were performed.

[0049] <Appearance of Finished Product> For Specimen [II], its finished appearance (such as gloss) was visually confirmed. The results are shown in Table 1. The evaluation criteria were based on a four-level scale (excellent: A > B > C > D: poor), where those with excellent finish were rated as "A" and those with poor finish were rated as "D".

[0050]

Table 1

Claims

1. A coating material is produced by uniformly mixing an oxidative-curing resin (A1) that is soluble in an aliphatic hydrocarbon-containing solvent (C) and has a weight-average molecular weight of 2,000 to 20,000, an oxidative-curing resin (A2) that is soluble in an aliphatic hydrocarbon-containing solvent (C) and has a weight-average molecular weight of 28,000 to 300,000, a metal dryer (B), and the aliphatic hydrocarbon-containing solvent (C), wherein the mixing ratio of the oxidative-curing resin (A1) to the oxidative-curing resin (A2) is a solid weight ratio of 99:1 to 50:

50. A method for forming a coating, characterized by applying an epoxy resin primer to a substrate, and then applying the coating material described above.

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