Environmentally friendly alkyd resin paint

Abstract

To provide an environment-responsive coating composition which is excellent in coating workability, surface dryness and coating film appearance using an alkyd resin that is excellent in surface dryness and adhesion and responds to environment, responds to safety of environment, and is excellent in viscosity adjustment and compatibility.SOLUTION: An environment-responsive coating composition contains an alkyd resin (A), an organic solvent (B) and a dryer (C), wherein the alkyd resin (A) contains a first alkyd resin (A1) composed of a phenol-modified alkyd resin, a content of the first alkyd resin (A1) occupied in the alkyd resin (A) is 5.0 to 20.0 mass%, and the organic solvent (B) has a content of an aromatic compound of 1,000 ppm or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an environmentally friendly alkyd resin paint.

Background Art

[0002] Conventionally, there has been a demand for paints having high functions that can meet social requirements such as not only protecting steel fixtures and giving them aesthetics but also preventing pollution to the natural environment, resource conservation, and protecting human health. Generally, the required performances of a paint composition include excellent storage stability, excellent surface drying property from the viewpoint of work efficiency, and excellent painting workability (for example, the property of easily forming a sufficient film thickness in a short time).

[0003] In addition, workers who apply paint to steel fixtures and users who use steel fixtures are required to deal with target chemical substances that are subject to the reporting obligation under the PRTR system in the "Law for Promotion of Chemical Substances Discharge Control" and specific chemical substances regulated by the "Regulations on Prevention of Specific Chemical Substances Hazards" (Special Regulations), because they may be harmed by chemical substances in organic solvents.

[0004] For example, Patent Document 1 discloses a one-component composition containing multiple modified epoxy resins, epoxy ester resins, and pigments for the purpose of exhibiting excellent rust prevention. It is described that this composition is easy to apply even at high concentrations and exhibits high rust prevention. Patent Document 2 discloses a paint composition containing two types of phenol-modified alkyd resins with different molecular weights, a silane coupling agent, and barium sulfate with a specified average particle size for the purpose of improving corrosion resistance and finish appearance. It is described that this composition provides excellent wet-on-wet suitability and high paint solid differentiation due to the two resins with different average molecular weights, corrosion-resistant film formation due to improved adhesion by the silane coupling agent, and a paint film with excellent finish appearance due to improved smoothness by the small average particle size of barium sulfate. Patent Document 3 discloses a paint composition containing a solvent, resin, and desiccant, with an alkyloxime material added as an anti-skinning agent for the purpose of preventing skinning. It is described that this composition prevents skinning by controlling the crosslinking of the resin with the alkyloxime material.

[0005] However, organic solvents that are not subject to the Specified Chemical Substances Act or PRTR (Pollutant Release and Transfer Register) have poor compatibility with alkyd resins, resulting in poor surface drying properties after coating, poor workability, and inferior appearance and adhesion after coating. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-152877 [Patent Document 2] Japanese Patent Publication No. 2020-037622 [Patent Document 3] Special Publication No. 2018-515644 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Therefore, the object of the present invention is to provide an environmentally friendly alkyd resin coating that uses an organic solvent that is not substantially subject to the Specified Chemical Substances Act or the PRTR system, and that has excellent compatibility, good coating workability, and excellent surface drying properties, coating film appearance, and adhesion after coating. [Means for solving the problem]

[0008] The features of this invention are listed below. (1) An environmentally friendly paint composition comprising an alkyd resin (A), an organic solvent (B), and a dryer (C), wherein the alkyd resin (A) includes a first alkyd resin (A1) made of a phenol-modified alkyd resin, and the content of the first alkyd resin (A1) in the alkyd resin (A) is 5.0 to 20.0% by mass, and the organic solvent (B) has an aromatic compound content of 1,000 ppm or less. (2) The environmentally friendly coating composition according to (1), wherein the alkyd resin (A) includes a second alkyd resin (A2) other than the first alkyd resin (A1), and the weight-average molecular weight of the second alkyd resin (A2) is 60,000 to 240,000. (3) The environmentally friendly coating composition according to (1), wherein the alkyd resin (A) comprises the second alkyd resin (A2), and the weight-average molecular weight of the second alkyd resin (A2) is 100,000 to 200,000. (4) The environmentally friendly paint composition according to (1) or (2), wherein the organic solvent (B) comprises a paraffinic hydrocarbon solvent (B1). (5) The environmentally friendly paint composition according to (1) or (2), wherein the dryer (C) contains a fatty acid metal salt. (6) The environmentally friendly paint composition according to (1) or (2), wherein the paint composition further comprises a resin (D) having an epoxy group. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an alkyd resin coating that uses an organic solvent that is substantially not subject to the Specified Chemical Substances Act or the PRTR system, and is an environmentally friendly alkyd resin coating that has excellent compatibility, good coating workability, and excellent surface drying properties, coating film appearance, and adhesion after coating. [Modes for carrying out the invention]

[0010] The environmentally friendly alkyd resin coating of the present invention will be described in detail below. Note that the following description illustrates one embodiment of the present invention and does not limit the scope of the present invention.

[0011] The environmentally friendly alkyd resin coating of the present invention is a coating composition comprising an organic solvent (B) and a dryer (C), wherein the alkyd resin (A) includes a first alkyd resin (A1) made of a phenol-modified alkyd resin, and the content of the first alkyd resin (A1) in the alkyd resin (A) is 5.0 to 20.0% by mass, and the organic solvent (B) has an aromatic compound content of 1000 ppm or less.

[0012] <Alkyd resin (A)> Alkyd resin (A) is a type of thermoplastic polyester resin obtained by condensation polymerization of polybasic acid components, polyhydric alcohol components, and unsaturated fatty acid components. It is used to create protective coatings with excellent weather resistance and is an important component of many synthetic paints due to its versatility and low cost. In the environmentally friendly paint composition of the present invention, alkyd resin (A) has high solubility and low viscosity, resulting in good workability, and also has good flowability, contributing to the gloss of the resulting coating film. In the present invention, there is no particular limitation as long as it is an alkyd resin (A) that can be applied to general paint compositions.

[0013] Examples of polybasic acid components that can be used as raw materials for alkyd resin (A) include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrophthalic acid, succinic acid, maleic acid, fumaric acid, adipic acid, itaconic acid, azelaic acid, pyromellitic acid, and their acid anhydrides.

[0014] Examples of polyhydric alcohol components include ethylene glycol, propylene glycol, butanediol, decanediol, diethylene glycol, pentanediol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0015] Examples of unsaturated fatty acid components include fatty acids from drying and semi-drying oils such as linseed oil, safflower oil, soybean oil, sesame oil, poppy oil, elm oil, corn oil, tall oil, sunflower oil, cottonseed oil, tung oil, dehydrated castor oil, and rice bran oil, as well as synthetic unsaturated fatty acids represented by hyale fatty acids.

[0016] The alkyd resin (A) applicable to the present invention may contain other components as raw materials for condensation polymerization. Examples of other components include monobasic acids such as benzoic acid and p-hydroxybenzoic acid. The alkyd resin (A) can be produced by known methods. For example, one method involves dehydrating and condensing each of the above raw material components in an inert gas atmosphere at approximately 200 to 240°C until the acid value is 10 or less.

[0017] <First Alkyd Resin (A1)> The first alkyd resin (A1) contained in the environmentally friendly coating composition of the present invention is a phenol-modified alkyd resin obtained by modifying alkyd resin (A) with a phenol resin. In the present invention, the phenol-modified alkyd resin is not particularly limited as long as it is generally applicable.

[0018] In the environmentally friendly paint composition of the present invention, the phenol-modified alkyd resin, which is the first alkyd resin (A1), can enhance the solvent resistance of the resulting paint film due to having a benzene ring. Furthermore, its low solubility in weak solvents and high glass transition temperature (Tg) impart drying properties to the formed paint film. In particular, when the first alkyd resin (A1) is blended at 5.0 to 20.0% by mass among the alkyd resins (A), the surface drying property becomes good. However, when the content of the first alkyd resin (A1) is more than 20.0% by mass, the paint film looks shriveled and the surface drying becomes prominent, so it tends to become in a sagging state and the appearance becomes poor.

[0019] As the phenol resin for modifying the alkyd resin (A), known phenol resins can be appropriately selected and used. For example, a resin obtained by reacting phenols and formaldehydes can be used. The method of reacting the phenol resin with the alkyd resin (A) is not particularly limited, and known methods can be applied. For example, a method of mixing the alkyd resin (A) and the phenol resin and heating and reacting them at a temperature of 120 to 180°C for about 1 to 10 hours can be mentioned. The phenol-modified alkyd resin, which is the first alkyd resin (A1) contained in the paint composition of the present invention, can also be a commercially available product. For example, Alkydia 1341 (manufactured by DIC Corporation), Arakide 7107 (manufactured by Arakawa Chemical Industries, Ltd.), HIRENOL PL-1000S (manufactured by Kolon Industries, Inc.) can be mentioned.

[0020] Examples of the modified phenols include phenols having one benzene ring in one molecule, such as phenol, methylphenol, p-ethylphenol, p-n-propylphenol, p-isopropylphenol, p-n-butylphenol, p-tert-butylphenol, p-tert-amylphenol, o-cresol, m-cresol, p-cresol, p-cyclohexylphenol, p-octylphenol, p-nonylphenol, 3,5-xylenol, resorcinol, catechol, etc.; phenols having two benzene rings in one molecule, such as phenylo-cresol, p-phenylphenol, etc.; bisphenol A, bisphenol F, etc. These can be used alone or in combination of two or more. Examples of the aldehydes include formaldehyde, paraformaldehyde, trioxane, etc.

[0021] In the environment-friendly paint composition of the present invention, the content of the first alkyd resin (A1) in the alkyd resin (A) is 5.0 to 20.0% by mass. The weight average molecular weight of the first alkyd resin (A1) composed of a phenol-modified alkyd resin is 40,000 to 200,000, preferably 45,000 to 150,000, and more preferably 50,000 to 90,000. From the viewpoint of the finished appearance, it is suitable that the mass of the phenol resin based on the total solid content of the first alkyd resin (A1) (phenol-modified alkyd resin) is within the range of 5.0 to 20.0% by mass, preferably 1.0 to 10.0% by mass.

[0022] <The second alkyd resin (A2)> Furthermore, the environment-friendly paint composition of the present invention contains a second alkyd resin (A2) other than the first alkyd resin (A1). The second alkyd resin (A2) can be appropriately selected from the above-mentioned alkyd resin (A). The alkyd resin (A) applicable to the present invention is not particularly limited, but from the viewpoint of appropriate surface drying properties, it is preferable that the weight-average molecular weight of the second alkyd resin (A2), other than the first alkyd resin (A1) made of phenol-modified alkyd resin, be 60,000 to 240,000, more preferably 100,000 to 200,000, and even more preferably 150,000 to 180,000.

[0023] Among these, the second alkyd resin (A2) may be modified, including acrylic modification, phenol modification, urethane modification, epoxy modification, and oil modification using various oils. In particular, it is preferable that the alkyd resin is modified by the reaction of a polymerizable vinyl monomer, and more preferably that it is an acrylic-modified alkyd resin. Such modified alkyd resins are preferable from the viewpoint of improving dispersion stability. An acrylic-modified alkyd resin is a modified alkyd resin using an acrylic component (acrylic acid, methacrylic acid and its esters, amides, and nitriles, etc.) as the polymerizable vinyl monomer, and it is preferable that the acrylic component is the main component. If the weight-average molecular weight of the second alkyd resin (A2) is too low, a tough film cannot be formed, and if the weight-average molecular weight is too high, it becomes difficult to dissolve during paint preparation, resulting in poor paint stability, etc. Therefore, the weight-average molecular weight is preferably 60,000 to 240,000, more preferably 100,000 to 200,000, and even more preferably 150,000 to 180,000.

[0024] The weight-average molecular weight of the resin in the environmentally friendly coating composition of the present invention is determined by converting the retention time (retention volume) measured using gel permeation chromatography (GPC) to the molecular weight of polystyrene using the retention time (retention volume) of standard polystyrene with a known molecular weight, measured under the same conditions. The gel permeation chromatography apparatus used was a TSKgel column (manufactured by Tosoh Corporation) equipped with a differential refractive index (RI) detector and size exclusion chromatography (SEC, trade name "HLC-8420GPC", manufactured by Tosoh Corporation). The SEC conditions were tetrahydrofuran as the developing solvent, with a flow rate of 0.35 ml / min and a temperature of 40°C. TSK standard polystyrene (manufactured by Tosoh Corporation) was used as the standard substance.

[0025] <Resin containing epoxy groups (D)> In the environmentally friendly coating composition of the present invention, a resin (D) having epoxy groups is preferred as the other resin. The resin (D) having epoxy groups is suitable for imparting adhesion to electrodeposited substrates. Examples of the resin (D) having epoxy groups used in the present invention include bisphenol-type epoxy resins such as bisphenol A-type epoxy resin and bisphenol F-type epoxy resin, naphthalene-type epoxy resin, biphenyl-type epoxy resin, novolac-type epoxy resin, cyclic aliphatic epoxy resin, glycidylamine-type resin, heterocyclic epoxy resin, and polyfunctional epoxy resin. These can be used alone or in combination. Specifically, solid epoxy resins synthesized from bisphenol A and epihalohydrin or epichlorohydrin, and solid epoxy resins obtained by an extension reaction between bisphenol A and a resin (D) having epoxy groups derived from bisphenol A, divalent phenols, and epihalohydrin, and bisphenol A are preferred.

[0026] The epoxy group-containing resin (D) can be used by mixing multiple epoxy group-containing resins (D) with different epoxy equivalents. The epoxy equivalent is not particularly limited, but is preferably between 400 and 3,000. It is also preferable to combine a resin with an epoxy equivalent of 1,000 or less with a resin with an epoxy equivalent of 1,000 or more, and the difference in epoxy equivalent between the epoxy resin with the minimum epoxy equivalent and the epoxy resin with the maximum epoxy equivalent is 300 or more, preferably 500 or more. From the viewpoint of coating film properties and painting workability, the weight-average molecular weight of the epoxy group-containing resin (D) is preferably between 100 and 600, more preferably between 250 and 500.

[0027] Examples of resins (D) having such epoxy groups include JER828, JER1004, JER1004F, JER1007, and JER4005P from Mitsubishi Chemical Corporation, EPICLON3050 and EPICLON4050 from DIC Corporation, EPOTOTE YD014D from Nippon Steel & Sumitomo Metal Chemical Corporation, and EPONANYANPES-904 from Nanya Plastics Co., Ltd.

[0028] <Other resins> Furthermore, the environmentally friendly coating composition of the present invention can be used by mixing a resin other than the first alkyd resin (A1) and the second alkyd resin as the resin component. Commonly used resins can be used as the resins to be mixed, but examples include acrylic resin, silicone resin, acrylic silicone resin, styrene-acrylic copolymer resin, polyester resin, fluororesin, rosin resin, petroleum resin, coumarone resin, phenolic resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, xylene resin, aliphatic hydrocarbon resin, butyral resin, maleic acid resin, fumaric acid resin, vinyl resin, amine resin, ketimine resin, and the like. These resins may be used individually or in combination of two or more.

[0029] <Organic solvent (B)> The environmentally friendly coating composition of the present invention is not particularly limited as an organic solvent (B), but includes aromatic hydrocarbon solvents such as xylene and toluene, ester solvents such as ethyl acetate, butyl acetate, isobutyl acetate, and methoxypropyl acetate, alcohol solvents such as isopropyl alcohol, butyl alcohol, and 1-methoxy-2-propanol, ether solvents such as dioxane, diethyl ether, and dibutyl ether, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and molecular formula C n H 2n+2 Examples of saturated chain compounds that can be represented as such include paraffinic hydrocarbon solvents such as octane, nonane, decane, dodecane, and tetradecane, which have straight and branched structures, and naphthenic hydrocarbon solvents such as cyclohexane and methylcyclohexane. Among these, esteric solvents and paraffinic hydrocarbon solvents are preferred. As esteric solvents, butyl acetate and ethyl acetate are preferred. As paraffinic hydrocarbon solvents, there are unbranched normal paraffins and branched isoparaffins, but isoparaffins with 10 or more carbon atoms are particularly preferred. These solvents can be used alone or in combination of two or more. Including 15.0% by mass of isoparaffinic hydrocarbon solvent makes it easier to adjust the viscosity to suit painting. Note that if only butyl acetate is used without using isoparaffinic hydrocarbon solvent, the solubility with alkyd resin (A) becomes too high, and the viscosity tends to decrease rapidly when the solvent is diluted. On the other hand, if the isoparaffinic hydrocarbon solvent is replaced with a hydrocarbon solvent with a low carbon number of less than 20 carbon atoms, the compatibility with alkyd resin (A) deteriorates, and clumping occurs.

[0030] The organic solvent (B) in the environmentally friendly coating composition of the present invention is an organic solvent that is not substantially subject to the Specified Chemical Substances Act or the PRTR system. In particular, the requirements for products (handled raw materials, materials, etc.) that are subject to the PRTR system when determining the annual handling volume and emissions are that products containing 1% by mass or more of the target chemical substance (Type I designated chemical substance), however, for specific Type I substances such as benzene, toluene, and xylene, the requirement is 0.1% by mass (1,000 ppm) or more. Therefore, the organic solvent (B) in the environmentally friendly coating composition of the present invention has an aromatic compound content of 1,000 ppm or less, preferably 500 ppm or less. The organic solvent (B) in the environmentally friendly coating composition of the present invention complies with the Specified Chemical Substances Act by substantially not using organic solvents containing aromatic compounds, and is environmentally friendly by preventing health hazards to users from the chemical substances of the organic solvent.

[0031] Typically, organic solvents (B) containing aromatic compounds with high solubility for organic compounds such as resins are used in paint compositions. Organic solvents (B) containing aromatic compounds are poorly soluble in water due to the presence of a benzene ring, but they have high solubility for organic compounds such as resins, and their low boiling point makes them highly volatile, thus improving the efficiency of painting work. However, they are harmful to the human body and carcinogenic, posing a risk of causing occupational cancer, dermatitis, and neurological disorders in workers. Therefore, the organic solvent (B) in the environmentally friendly paint composition of the present invention substantially does not contain organic solvents containing aromatic compounds that are subject to the Specified Chemical Substances Act and the PRTR system, and instead contains alcohol-based solvents, glycol ether-based solvents, and paraffin-based solvents, thereby increasing solubility with alkyd resin (A) and improving paint compatibility, paint workability, surface drying properties, appearance, and adhesion.

[0032] Aromatic solvents are solvents containing aromatic compounds and compounds having a benzene ring in a resonance state within the molecule, such as benzene, toluene, xylene, ethylbenzene, naphthalene, styrene monomer, and C9 to C11 aromatic hydrocarbon mixtures.

[0033] The content of organic solvent (B) in this invention is 50% by mass or less relative to the paint composition. If the content of organic solvent (B) exceeds 50% by mass, the compatibility improves. However, the drying time during painting increases, and the paintability decreases. Furthermore, the likelihood of the applicator absorbing the solvent increases, increasing the risk of health damage. The lower limit of the content of organic solvent (B) that does not contain aromatic compounds in this invention is the content at which the viscosity of the paint composition becomes unsuitable for application.

[0034] <Hair dryer (C)> The environmentally friendly coating composition of the present invention contains a dryer (C). The dryer (C) acts as a curing catalyst to accelerate the curing of the primer coating composition and dry the surface of the painted coating. The dryer (C) uses a metal salt compound of a metal and a fatty acid. Examples of metals include cobalt, manganese, zirconium, lithium, barium, zinc, copper, iron, calcium, magnesium, cerium, aluminum, and strontium. Examples of fatty acids include octic acid, naphthenic acid, neodecanoic acid, butyric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, ligrinoceric acid, cerotic acid, montanic acid, melissic acid, sucroseic acid, lindelic acid, tuzic acid, makous acid, myristooleic acid, zomaric acid, petroseric acid, oleic acid, vaccenic acid, gadoleic acid, whale oil acid, erucic acid, shark oil acid, linoleic acid, hiragonic acid, eleostearic acid, bunic acid, tricosanic acid, linolenic acid, moloctic acid, parinaric acid, arachidonic acid, sardine acid, hiragashilic acid, herringic acid, soybean oil fatty acid, stearic acid, tall oil fatty acid, etc.

[0035] Dryer (C) can specifically include cobalt octoate, zirconium naphthenate, cobalt naphthenate, barium naphthenate, zirconium octoate, barium octoate, zinc naphthenate, copper naphthenate, iron naphthenate, calcium naphthenate, magnesium naphthenate, zinc octoate, copper octoate, iron octoate, calcium octoate, magnesium octoate, cerium octoate, aluminum octoate, calcium neodecanoate, etc. These can be used individually or in combination of two or more. Cobalt octoate and zirconium octoate are particularly preferred.

[0036] The amount of dryer (C) added can be in the range of 0.01 to 2.5% by mass relative to 100% by mass of alkyd resin (A). Dryer (C) contributes to the hardening of the coating surface and, in particular, to the hardening of the inside of the coating. As a result, the environmentally friendly coating composition of the present invention yields a coating film with good adhesion to the substrate, excellent surface drying properties, and excellent weather resistance.

[0037] <Pigment (E)> The environmentally friendly coating composition of the present invention preferably contains a pigment (E). The inclusion of a pigment (E) allows for the formation of a coating film with excellent compatibility and surface drying properties. It is necessary to contain at least an extender pigment (E1), and optionally, a coloring pigment (E2), a rust-preventive pigment (E3), and a gloss pigment (E4).

[0038] <<Extender Pigment (E1)>> Extender pigments (E1) are white or colorless pigments. Because they have a low refractive index, they have little effect on opacity when mixed with binders, and are used as fillers to adjust color strength, gloss, strength, and feel. Known materials can be used as extender pigments (E1), such as precipitated barium sulfate, silica, cristobalite, calcium carbonate, alumina, alum, white clay, magnesium hydroxide, and magnesium oxide. Extender pigments (E1) may also be thin, flat pigments (flak-like pigments), such as glass flakes, talc, mica, and kaolin clay.

[0039] The environmentally friendly paint composition of the present invention preferably contains precipitated barium sulfate as an extender pigment. Barium sulfate is an ionic crystalline compound composed of barium ions and sulfate ions. Since it is completely insoluble in acid and not absorbed by the human body, it is non-toxic and therefore suitable for environmentally friendly paint compositions. The pigment (E) contained in the environmentally friendly paint composition of the present invention contains an extender pigment (E1) with an average particle size of 10 μm or less. Here, the average particle size of the pigment is determined by observing the particles using a scanning electron microscope or the like, measuring the maximum length of the particles (the longest length between any two points on the circumference of the particle), and taking the number average of these values ​​as the average particle size. If the particles are photographed as aggregates, the particle diameter of the primary particles forming the aggregates is measured.

[0040] Furthermore, the pigment (E) contained in the environmentally friendly paint composition of the present invention contains an extender pigment (E1) with an oil absorption capacity of 15 ml / 100g or more and 25 ml / 100g or less. Here, the oil absorption amount is measured using the refined linseed oil method according to the JIS standard (JIS K 5101-13-1). When the oil absorption amount of pigment (E) is greater than 25 ml / 100 g, the surface area of ​​the pigment is large and the surface shape becomes complex, which improves the appearance and adhesion of the coating film. When the oil absorption amount is small, less than 15 ml / 100 g, the compatibility of the paint and the surface drying properties of the coating film are greatly reduced. Furthermore, a range of 15 ml / 100 g to 20 ml / 100 g is preferable.

[0041] <<Coloring Pigment (E2)>> Coloring pigments (E2) are broadly classified into inorganic pigments and organic pigments based on their composition. Examples of inorganic pigments include titanium dioxide, red iron oxide, yellow iron oxide, and carbon black, while examples of organic pigments include phthalocyanine blue, phthalocyanine green, naphthol red, quinacridone red, benzimidazolone yellow, Hansa yellow, benzimidazolone orange, and dioxazine violet.

[0042] Furthermore, in the environmentally friendly coating composition of the present invention, the pigment content in the solid content of the film-forming component is preferably 6% by mass or more and 10% by mass or less. If the content is less than 6% by mass, compatibility is excellent, but the workability of the coating decreases and the surface drying performance decreases. If the content exceeds 10% by mass, adhesion decreases and coating defects occur in appearance.

[0043] <Other additives (F)> The environmentally friendly coating composition of the present invention may appropriately incorporate other additives as needed, such as other resins, matting agents, flexibility agents, surface modifiers, wetting agents, dispersants, emulsifiers, viscosity modifiers, settling inhibitors, anti-skinning agents, anti-sagging agents, defoaming agents, color separation inhibitors, leveling agents, drying agents, plasticizers, film-forming aids, antifungal agents, antibacterial agents, insecticides, light stabilizers, UV absorbers, electrostatic lubricants, antistatic agents, and conductivity modifiers. Commercially available products can be suitably used for these components.

[0044] <<Viscosity modifier (F1)>> The environmentally friendly coating composition of the present invention can use the following viscosity modifiers: inorganic viscosity modifiers such as sodium silicate and bentonite; cellulose viscosity modifiers such as methylcellulose, carboxymethylcellulose, and hydroxymethylcellulose with a number average molecular weight of 20,000 or more; protein viscosity modifiers such as casein, sodium caseinate, and ammonium caseinate; acrylic viscosity modifiers such as sodium polyacrylate and ammonium polyacrylate with a number average molecular weight of 20,000 or more; and vinyl viscosity modifiers such as polyvinyl alcohol with a number average molecular weight of 20,000 or more. In particular, inorganic viscosity modifiers are preferred, and bentonite is especially preferred. By including bentonite, viscosity can be easily adjusted, and the composition is heat resistant and less prone to degradation.

[0045] <<Dispersant (F2)>> The environmentally friendly coating composition of the present invention can be used as a dispersant to increase the viscosity of the coating composition and form a smooth surface. While the dispersant is not particularly limited, viscosity can be increased by using a surfactant as an emulsifier. Examples of such surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. When such surfactants are included in the repair coating, an emulsion containing alkyd resin and an organic solvent can be formed. Cationic surfactants are particularly preferred. Cationic surfactants improve dispersibility, resulting in improved color and gloss when the coating film is formed.

[0046] <<Surface modifier (F3)>> The environmentally friendly coating composition of the present invention can use silicone-based additives, fluorine-based additives, cellulose-based additives, etc., as surface modifiers. Silicone-based additives have the effect of preventing repelling when applied to metal substrates by lowering surface tension and improving wettability. Specific examples of silicone-based additives include dimethyl silicone oil. Furthermore, methyl silicone oil excels in surface drying properties and the appearance of the coating film surface, and since prioritizing surface drying properties tends to result in a loss of the coating film surface appearance, it can achieve both conflicting performances.

[0047] <<Anti-skinning agent (F4)>> The environmentally friendly coating composition of the present invention can be used with an anti-skinning agent to prevent the phenomenon of skin formation on the surface of a painted coating when it comes into contact with air. Examples of anti-skinning agents include oxime-based anti-skinning agents such as methyl ethyl ketone oxime, and phenol-based anti-skinning agents such as 2,6-di-tert-butyl-p-cresol (BHT), butylated hydroxyanisole (BHA), and 2,2-methylene-bis(4-methyl-6-tert-butylphenol). Methyl ethyl ketone oxime is particularly preferred. Some anti-skinning agents suppress oxidation by reducing contact with air, but may worsen surface drying properties. Methyl ethyl ketone oxime does not adversely affect surface drying properties and can moderately reduce contact with air and suppress oxidation.

[0048] These additives (F) can further improve the compatibility, paintability, surface drying properties after painting, film appearance, and adhesion of the environmentally friendly coating composition of the present invention. In the environmentally friendly coating composition of the present invention, these additives (F) may be used individually or in combination of two or more. The content of additive (F) in the environmentally friendly coating composition of the present invention is preferably 0.1 to 10% by mass.

[0049] <Method for manufacturing environmentally friendly paint compositions> The environmentally friendly coating composition of the present invention is prepared, for example, by mixing an alkyd resin (A), an organic solvent (B), and a dryer (C) with various additives as appropriate, and stirring and kneading them together. In this process, it is preferable to use an SG mill or the like to disperse the mixture as uniformly as possible.

[0050] <Application Method> The environmentally friendly coating composition of the present invention is not particularly limited in terms of application method, and known application methods include, for example, dipping method, spin coating method, flow coating method, roll coating method, spray coating method, blade coating method, and air knife coating method.

[0051] <Applications of environmentally friendly paint compositions> The environmentally friendly coating composition of the present invention can be used for spray coating and dipping coating, and examples of objects to be coated include structures such as buildings and structures, vehicles (automobiles, etc.), furniture, fixtures, electronic equipment (home appliances, etc.), and their parts, which have a coating film on the surface of a metal substrate. The metal substrate is not particularly limited, but its shape can be, for example, plate-like, sheet-like, or foil-like. The metal constituting the substrate can be iron or steel, galvanized steel, stainless steel, magnesium alloy, aluminum, aluminum alloy, etc., with iron or steel being preferred. Furthermore, the metal substrate may be subjected to various surface treatments, such as oxidation treatment. As an example, substrates of iron or aluminum that have been oxidized by methods such as anodizing, phosphate treatment, chromate treatment, or non-chromate treatment can be used. The metal substrate also includes various plastic substrates having a thin metal film on their surface (their shape can be, for example, a housing and film with a three-dimensional structure). For metal film formation, vapor deposition, sputtering, plating, etc. can be used. Examples of thin metal films include thin films of metals such as aluminum, tin, zinc, gold, silver, platinum, and nickel. The amount of the environmentally friendly coating composition of the present invention applied can be varied depending on the type of substrate to which it is applied and its intended use. [Examples]

[0052] Examples of the present invention are described below. The present invention can be in various forms and is not limited to the following examples.

[0053] <Preparation of Examples 1-12 and Comparative Examples 1-5> According to the formulations shown in Table 1 (values ​​are in parts by mass), a first alkyd resin (A1) using a phenol-modified alkyd resin and a second alkyd resin (A2) that does not use the first alkyd resin (A1) were pre-mixed with butyl acetate and a C8-C15 paraffin-based solvent as organic solvents (B), carbon black as a pigment, precipitated barium sulfate, and other materials such as viscosity modifiers and dispersants. The mixture was then dispersed using a bead mill to produce a compound.

[0054] The mixture obtained through this dispersion process was further mixed with a phenol-modified alkyd resin (A1) and a phenol-modified alkyd resin (A2) from among the alkyd resins (A), an epoxy resin (D), an organic solvent (B) consisting of butyl acetate, ethyl acetate, and a C8-C15 paraffin-based solvent, a dryer (C) consisting of zirconium octoate and cobalt octoate, and other materials such as a surface modifier and an anti-skinning agent, all while stirring, to produce environmentally friendly oil-based paint compositions (Examples 1-12, Comparative Examples 1-5).

[0055] Table 1 shows details of the raw materials used and examples of formulations. (1) Alkyd resin (A) (Preparation of alkyd resin) Soybean oil fatty acids, castor oil fatty acids, pentaerythritol, ethylene glycol, benzoic acid, phthalic anhydride, and a high-boiling point aromatic solvent S100 as an azeotropic solvent were placed in a reaction vessel and the esterification reaction was carried out while stirring and removing the generated water. The reaction mixture was heated from 150°C to 235°C over 6 hours and the reaction was carried out while maintaining this temperature. At the end of the reaction, a sample of the reaction system was taken and the acid value of the sampled reaction system was measured. The reaction was considered to have ended when the acid value dropped from 7 to 13. The acid value was measured by manual standardization with a methanol solution of 1 / 10 N potassium hydroxide using phenolphthalein as an indicator. The reaction vessel used for the reaction was prepared by purging it with nitrogen before adding the raw materials and blowing in nitrogen gas.

[0056] (Preparation of phenol-modified alkyd resin) Alkyd resin, butyl acetate, and styrene were placed in a reaction vessel and stirred under heating. After reaching 110°C, methyl methacrylate, styrene, and a mixture of NOF Corporation's Niper BMT-40(SV) and tert-butyl peroxy-2-ethylhexanoate (pre-mixed) as polymerization initiators were added dropwise over 1 hour. After the dropwise addition was complete, while maintaining the reaction mixture at 110°C, a mixture of NOF Corporation's Niper BMT-40(SV) and tert-butyl peroxy-2-ethylhexanoate as polymerization initiators and butyl acetate as solvent was added dropwise over 3 hours, and the mixture was continued to stir at 110°C for 1 hour to complete the preparation.

[0057] Next, by adjusting the amounts of the transesterified product, glycerin, and phthalic anhydride, we prepared the first and second alkyd resins with different weight-average molecular weights, as shown below. (A1-1) Primary alkyd resin (phenol-modified alkyd resin: weight-average molecular weight: 22,000) (A1-2) First alkyd resin (phenol-modified alkyd resin (weight-average molecular weight: 20,000) (A2-1) Second alkyd resin (alkyd resin, weight-average molecular weight: 150,000) (A2-2) Second alkyd resin (alkyd resin, weight-average molecular weight: 100,000) (A2-3) Second alkyd resin (alkyd resin, weight-average molecular weight: 60,000) (A2-4) Second alkyd resin (alkyd resin, weight-average molecular weight: 200,000) (A2-5) Second alkyd resin (alkyd resin, weight-average molecular weight: 250,000)

[0058] (2) Epoxy resin (D) (D-1) Epoxy resin (Epoxy resin (product name: JER828, manufactured by Mitsubishi Chemical Corporation), weight-average molecular weight: 370) (D-2) Epoxy resin (Epoxy resin (product name: JER815, manufactured by Mitsubishi Chemical Corporation), weight-average molecular weight: 370)

[0059] (3) Hair dryer (C) (C-1) Fatty acid metal salt (Zirconium octoate (Trade name: 12% Zr-OCTOATE, manufactured by DIC Corporation)) (C-2) Fatty acid metal salt (cobalt octoate (product name: Co-OCTOATE, manufactured by DIC Corporation))

[0060] (4) Pigment (E) (E-1) Coloring pigment (carbon black (product name: Mitsubishi Carbon Black MA100, manufactured by Mitsubishi Chemical Corporation)) (E-2) Extender pigment (Precipitated barium sulfate (product name: Precipitated barium sulfate, manufactured by Kawatsu Sangyo Co., Ltd.))

[0061] (5) Other (F) (F-1) Viscosity modifier (0.50 parts by mass: (Product name: ANTI-TERRA-U, manufactured by Bic Chemie)) (F-2) Dispersant (0.07 parts by mass: (Product name: Homogenol L-95, manufactured by Kao Corporation)) (F-3) Surface modifier (0.10 parts by mass: (Product name: KF-69, manufactured by Shin-Etsu Chemical Co., Ltd.)) (F-4) Anti-skinning agent (0.30 parts by mass: (Product name: MEK Oxime, manufactured by Ube Industries, Ltd.))

[0062] (7) Organic solvents (B) (B-1) Ester-based solvent (butyl acetate (product name: butyl acetate, manufactured by Shoei Chemical Co., Ltd.)) (B-2) Ester solvent (ethyl acetate (product name: ethyl acetate, manufactured by Shoei Chemical Co., Ltd.)) (B-3) Isoparaffinic solvent (C8-C15 isoparaffin mixture (product name: IP Solvent 1620, manufactured by Idemitsu Kosan Co., Ltd.)) (B-4) Aromatic solvent (toluene (unknown due to impurities))

[0063] Table 1 shows Examples 1 to 12 prepared according to the formulation. Table 2 shows Comparative Examples 1-5, which were prepared according to the formulation.

[0064] [Table 1]

[0065] [Table 2]

[0066] <Evaluation of paint performance and coating performance> Compatibility was evaluated as the paint performance of Examples 1-12 and Comparative Examples 1-5. Furthermore, the coating performance of the samples (coated bodies) in Examples 1 to 12 and Comparative Examples 1 to 5 was evaluated as paintability, surface drying properties, appearance, and adhesion. The test panels were prepared by applying the prepared environmentally friendly coating composition uniformly to a non-chromate treated galvanized steel sheet using an air spray, and then drying it at a constant temperature for a constant time to form the test coating. The evaluation method is described below. Table 3 shows the evaluation results for Examples 1 to 12. Furthermore, Table 4 shows the evaluation results for Comparative Examples 1 to 5.

[0067] <<Compatibility>> Each sample was mixed with an equal amount of organic solvent as its solid content, thoroughly stirred, and then allowed to stand at 25°C for 24 hours. Separation was then confirmed visually. The evaluation criteria are as follows: ○: Dissolves in solvent and does not separate the next day. ×: Dissolves in the solvent, but separates by the next day, or does not dissolve at all.

[0068] <<Evaluation of paintability>> After thorough mixing, painting was performed using an air sprayer. The paint application process was then evaluated. The evaluation criteria were as follows: ○: When the atomization properties and the state of adhesion to the painted surface are at the same level as those of non-environmentally compliant products. △: This indicates that the atomization properties or the state of adhesion to the painted surface are slightly inferior compared to products that are not environmentally friendly. ×: Although dissolution is possible with a diluent, if there are obvious problems during painting. -: Evaluation is not possible due to poor compatibility between the resin and solvent in the paint.

[0069] <<Evaluation of surface drying properties>> After thorough stirring, the coating was applied using an air spray to achieve a film thickness of 30-40 μm. After coating, the surface was left to stand for 1 hour at 22°C and 50% RH. Subsequently, the surface drying properties of the coating were evaluated according to JIS K5600-1-1:1999. The evaluation criteria were as follows: ○: When you touch the painted surface with your fingertip, no fingerprints or other marks are left, and when you lift your finger, you do not feel any stickiness. △: When touching the painted surface with a fingertip, some fingerprints and other marks remain, but no stickiness is felt when the finger is lifted. do not have If it is in that state ×: When the painted surface is touched with a fingertip, fingerprints or other marks are left behind, and when the finger is lifted, a sticky feeling is felt. -: The compatibility between the resin and solvent in the paint is poor, making it impossible to evaluate the surface drying properties.

[0070] <<Evaluation of appearance>> After thorough stirring, the coating was applied using an air sprayer to achieve a post-drying film thickness of 30-40 μm. After coating, the surface was left to stand for 1 hour at 23°C and 50% RH. The appearance of the coating surface was then evaluated according to JIS K5600-1-1:1999. The evaluation criteria were as follows: ○: Compared to non-environmentally compliant products, the color, gloss, and paint film condition are at the same level, and there are no general defects in the paint film. △: Compared to non-environmentally compliant products, there are differences in color, gloss, or coating condition, but there are no general coating defects. ×: This indicates a general coating defect. -: When the appearance cannot be evaluated due to poor compatibility between the resin and solvent in the paint.

[0071] <<Evaluation of Adhesion>> After thorough stirring, the coating was applied using an air sprayer to achieve a post-drying film thickness of 30-40 μm. After coating, the surface was left to stand for 1 hour at 23°C and 50% RH. Adhesion was then evaluated on the coating surface using JIS K 5600-5-6:1999 (cross-cut method: 1 mm x 100 grids, material: SPCC-SB). The evaluation criteria were as follows. ○: When the edges of the cut are perfectly smooth and there is no peeling at any of the grid lines. △: Small peeling of the coating is observed at the intersection of the cuts, but the area of ​​peeling relative to the total coating area is less than 5%. ×: When the area of ​​peeling off the paint film is 5% or more of the total paint film area due to cross-cutting. -: Evaluation is not possible due to poor compatibility between the resin and solvent in the paint.

[0072] [Table 3]

[0073] [Table 4]

[0074] As shown in Table 3, the environmentally friendly coating compositions of Examples 1 to 12 all received a rating of "○" or "△" for compatibility, paintability, surface drying properties, appearance, and adhesion, indicating no practical problems.

[0075] As shown in Table 4, the sample of Comparative Example 1 contains the aromatic solvent B-4:toluene, resulting in a "×" in compatibility. Furthermore, it is impossible to evaluate its paintability, surface drying properties, appearance, or adhesion.

[0076] The sample in Comparative Example 2, lacking a dryer (C), exhibits a "×" rating for surface drying properties.

[0077] In Comparative Example 3, the content of the first alkyd resin relative to the alkyd resin was outside the lower limit range, resulting in a "×" for surface drying properties.

[0078] In Comparative Example 4, the content of the first alkyd resin relative to the alkyd resin was outside the lower limit range, resulting in a "×" rating for appearance and adhesion.

[0079] The sample in Comparative Example 5, lacking the first alkyd resin and dryer, exhibits a "×" rating for surface drying properties.

[0080] From the results of Examples 1-12 and Comparative Examples 1-5, it was found that the one-component epoxy resin coating composition of the present invention has no practical problems in terms of compatibility, paintability, surface drying properties, appearance, and adhesion.

Claims

1. A paint composition comprising an alkyd resin (A), an organic solvent (B), and a dryer (C), The alkyd resin (A) comprises a first alkyd resin (A1) made of a phenol-modified alkyd resin and a second alkyd resin (A2) other than the first alkyd resin (A1), and The content of the first alkyd resin (A1) in the alkyd resin (A) is 5.0 to 20.0% by mass, and the weight-average molecular weight of the second alkyd resin (A2) is 100,000 to 200,000. The organic solvent (B) is an environmentally friendly coating composition having an aromatic compound content of 1,000 ppm or less and comprising an ester-based solvent and an isoparaffinic hydrocarbon solvent.

2. The environmentally friendly paint composition according to claim 1, wherein the dryer (C) contains a fatty acid metal salt.

3. The environmentally friendly paint composition according to claim 1, wherein the paint composition further comprises a resin (D) having an epoxy group.

Images