JP2011219550A - Coating resin composition and primer coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating resin composition which is diluted with a weak solvent such as a mineral spirit etc., has excellent initial drying properties and adhesive properties and is useful especially as a primer coating.SOLUTION: The coating resin composition includes a rosin modified epoxy ester resin (A) and a phenol modified alkyd resin (B). The rosin modified epoxy ester resin (A) is obtained by reacting an epoxy resin (a1) containing two or more epoxy groups in one molecule with a rosin (a2), a fatty acid (a3) and a polyisocyanate compound (a4) and the use ratio of the rosin modified epoxy ester resin (A) and the phenol modified alkyd resin (B) is in the range of 70/30-10/90 by a solid content mass ratio of (A)/(B).

Description

  The present invention relates to a coating resin composition that can be diluted with a weak solvent such as mineral spirit and is excellent in initial drying property and adhesion, and particularly useful as a primer coating.

  Epoxy resin paint with excellent corrosion resistance, chemical resistance, adhesion, etc. to protect metal parts of buildings, steel structures such as bridges, plants, tanks, and metal products such as steel sheets and steel pipes from the corrosive environment of the outside world Is widely used. Epoxy resins used in such epoxy resin coatings are generally highly polar and therefore soluble in organic solvents such as aromatic hydrocarbons such as toluene and xylene, and ketones such as methyl ethyl ketone. It has been.

  However, these organic solvents exhibit excellent solubility in epoxy resins, but on the other hand, they are highly harmful to human bodies and have a low flash point and boiling point. For this reason, epoxy resin paints using these organic solvents have problems in terms of work environment hygiene and safety, and when the old paint film is fragile, the old paint film is redissolved or swelled during repainting. There was also a problem that a lifting phenomenon (chijimi) of the coating film occurred.

  As a measure against such a problem, the importance of developing an epoxy resin paint that can be dissolved in a weak solvent such as an organic solvent having a high flash point, a high boiling point, and a relatively low environmental load, such as mineral spirit, is increasing.

  As an epoxy resin that can be dissolved in a weak solvent, for example, Patent Documents 1 and 2 disclose modified epoxy resins obtained by reacting an epoxy resin with an aliphatic monocarboxylic acid, a diisocyanate compound, or an alkylphenol.

  The modified epoxy resin can be dissolved in a weak solvent or can be stably dispersed, but the dryness of the coating film and the physical properties of the coating film are not satisfactory, and the coating viscosity becomes high, and the coating work In order to ensure the properties, a large amount of the organic solvent is added, so that the amount of the organic solvent in the paint increases.

  For such problems, Patent Document 3 proposes a modified epoxy resin that uses a specific aliphatic monocarboxylic acid and that has a specific range of the amount of modification of the aliphatic monocarboxylic acid and isocyanate.

  Such a modified epoxy resin has a good solubility in mineral spirits, and a paint containing the modified epoxy resin can be made into a high solid and the physical properties of the formed coating film are good, but in terms of initial drying properties. It is insufficient.

Japanese Patent Laid-Open No. 3-115318 JP-A-4-39320 JP-A-9-143246

  The object of the present invention is to propose a coating resin composition useful as a primer paint that can be diluted with a weak solvent such as mineral spirit and is suitable for forming a coating film excellent in initial drying property and adhesion. It is in.

As a result of intensive studies on the above-mentioned problems, the inventors of the present invention formed a coating film excellent in initial drying and adhesion by combining rosin-modified epoxy ester resin and phenol-modified alkyd resin at a specific blending ratio. We have found that we can do it and have arrived at the present invention. That is, the present invention
1. A coating resin composition comprising a rosin-modified epoxy ester resin (A) and a phenol-modified alkyd resin (B), wherein the rosin-modified epoxy ester resin (A) has two or more epoxy groups in one molecule. Epoxy resin (a1), rosin (a2), fatty acid (a3), and polyisocyanate compound (a4) having a rosin-modified epoxy ester resin (A) and a phenol-modified alkyd resin A coating resin composition characterized in that the use ratio of (B) is in the range of 70/30 to 10/90 in terms of (A) / (B) solid content mass ratio,
2. In the rosin-modified epoxy ester resin (A), the use ratio of the epoxy resin (a1), the rosin (a2) and the fatty acid (a3) is that of the rosin (a2) with respect to 1 equivalent of the epoxy group contained in the epoxy resin (a1). The sum of the equivalents of the carboxyl group and the carboxyl group of the fatty acid (a3) is in the range of 0.9 to 1.1 equivalents, and the equivalent ratio of the carboxyl group of the rosins (a2) and the carboxyl group of the fatty acid (a3) is The resin composition for coating according to 1, wherein the ratio (a2) / (a3) is in the range of 1/9 to 6/4,
3. In the rosin-modified epoxy ester resin (A), the amount of the polyisocyanate compound (a4) used is
The isocyanate group equivalent in (a4) is within the range of 0.1 to 0.9 equivalent to 1 equivalent of hydroxyl group in the reaction product obtained from the epoxy resin (a1), rosin (a2) and fatty acid (a3). The coating resin composition according to item 1 or 2, which is an amount of
4). Items 1 to 3 wherein the phenol-modified alkyd resin (B) comprises animal and vegetable oils or fats or fatty acids thereof (b1), polybasic acids (b2), polyhydric alcohols (b3), and phenol resins (b4). The resin composition for coating according to any one of
5. The coating resin composition according to 4, wherein the amount of the phenol resin (b4) used is in the range of 0.5 to 10 parts by mass based on 100 parts by mass of the alkyd resin (B) solid content,
6). A primer paint comprising the coating resin composition according to any one of claims 1 to 5,
7). A coating method for applying the primer paint according to item 6 on the substrate surface;
About.

  According to the coating resin composition according to the present invention, it can be easily diluted with a weak solvent such as mineral spirit, and the initial drying property immediately after coating is excellent even under drying conditions at room temperature, and the adhesiveness is excellent. Is also useful as a primer paint because an excellent coating film can be formed.

  The coating resin composition of the present invention comprises a rosin-modified epoxy ester resin (A) and a phenol-modified alkyd resin (B).

≪Rosin modified epoxy ester resin (A) ≫
In the present invention, rosin-modified epoxy ester resin (A) is obtained by reacting epoxy resin (a1) having two or more epoxy groups in one molecule, rosin (a2), fatty acid (a3) and polyisocyanate compound (a4). It is resin obtained by making it.

  Examples of the resin (a) having two or more epoxy groups in one molecule include epoxy resins derived from dihydroxybenzenes and epichlorohydrin, alkylphenol novolac resins and alkylphenol novolac epoxy resins derived from epichlorohydrin; A-type epoxy resin, bisphenol F-type epoxy resin, hydrogenated bisphenol A-type epoxy resin, hydrogenated bisphenol F-type epoxy resin, and the like can be used. A bisphenol A type epoxy resin is preferable from the viewpoint of adhesion of a coating film formed from the resin composition.

  Moreover, since the solubility with respect to weak solvents, such as a mineral spirit, improves and the selectivity of the organic solvent which can be used becomes wide, it is preferable also in order to ensure the softness | flexibility of a coating film that an epoxy equivalent is 300 or less.

  In this specification, epoxy equivalent (g / eq) is the mass (g) of resin per gram equivalent of epoxy group, and can be measured as follows based on JIS K7236 (1995).

  The sample epoxy resin was dissolved in chloroform and acetic acid, 10 ml of a solution of 100 g of tetraethylammonium bromide dissolved in 400 ml of acetic acid was added to the solution, and titrated with perchloric acid acetic acid solution using crystal violet as an indicator. calculate.

  Epoxy equivalent (g / eq) = 1000 × m / (C × V) Formula.

  m: sample solid content mass (g), C: concentration of perchloric acid acetic acid in titrant, V: titration.

  The weak solvent generally means an organic solvent having a weak dissolving power and is not strictly distinguished. For example, the weak solvent is selected from an aliphatic hydrocarbon solvent and an aromatic hydrocarbon solvent. And hydrocarbon solvents having a boiling point of 148 ° C. or higher.

  Specific examples of the weak solvent include, for example, mineral spirit, white spirit, mineral turpentine, isoparaffin, solvent kerosene, aromatic naphtha, VM & P naphtha, solvent naphtha, and petroleum naphtha. Examples of these commercially available products include “Solvesso 100”, “Solvesso 150”, “Solvesso 200”, “Essonaphtha No. 6” (manufactured by Esso Oil Co., Ltd.); “Swazol 1000”, “Swazol 1500” (and above, "Ipsol 100" (manufactured by Idemitsu Kosan Co., Ltd.); "HAWS", "LAWS" (manufactured by Shell Chemicals Japan Co., Ltd.); "A Solvent" (manufactured by Nippon Oil Co., Ltd.), etc. Can be mentioned.

  Examples of the rosins (a2) include natural rosins such as gum rosin, tall rosin, and wood rosin; polymerized rosins derived from the natural rosins; stabilized rosins obtained by disproportionating or hydrogenating the natural rosins and polymerized rosins ; Unsaturated acid-modified rosin such as maleic acid-modified rosin, maleic anhydride rosin, fumaric acid-modified rosin, itaconic acid-modified rosin, crotonic acid-modified rosin, cinnamic acid-modified rosin, acrylic acid-modified rosin, methacrylic acid-modified rosin, etc. These may be used alone or in combination of two or more. Of these, natural rosin, particularly gum rosin or tall rosin is preferred.

  As the fatty acid (a3), conventionally known dry oil fatty acid, non-drying oil fatty acid, saturated fatty acid and the like can be used without particular limitation, fish oil fatty acid, dehydrated castor oil fatty acid, safflower oil fatty acid, linseed oil fatty acid, soybean oil fatty acid, Dry oil fatty acids such as sesame oil fatty acid, poppy oil fatty acid, eno oil fatty acid, hemp oil fatty acid, grape kernel oil fatty acid, corn oil fatty acid, tall oil fatty acid, sunflower oil fatty acid, cottonseed oil fatty acid, walnut oil fatty acid, rubber seed oil fatty acid; Non-drying oil fatty acids such as oil fatty acids, hydrogenated coconut oil fatty acids and palm oil fatty acids; saturated fatty acids such as caproic acid, capric acid, lauric acid, myristic acid, palmitic acid and stearic acid; In the present invention, it is suitable to use a dry oil fatty acid as the fatty acid (a3) from the viewpoint of the initial drying property of the formed coating film and the curability at room temperature.

  Examples of the polyisocyanate compound (a4) include tolylene diisocyanate (usually called “TDI”), xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,4′-diisocyanate, diphenylmethane-4,4′-diisocyanate (usually “MDI”). Aromatic, aliphatic or cycloaliphatic polyisocyanate compounds such as crude MDI, bis (isocyanate methyl) cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate (commonly referred to as “IPDI”); Cyclized polymers of these polyisocyanate compounds, isocyanate violets; ethylene glycol in excess of these polyisocyanate compounds, Examples thereof include terminal isocyanate-containing compounds obtained by reacting low-molecular active hydrogen-containing compounds such as propylene glycol, trimethylolpropane, hexanetriol, and castor oil. These can be used alone or in combination of two or more.

  In the present invention, the rosin-modified epoxy ester resin (A) can be produced as follows.

  First, the epoxy resin (a1), rosin (a2), and fatty acid (a3) mixture are heated to 100 to 160 ° C. until the acid value becomes approximately 1 mg KOH / g or less, thereby producing a reaction having a hydroxyl group. Manufacturing things.

  At this time, an epoxy group / carboxyl group reaction catalyst may be used as necessary.

  Examples of epoxy group / carboxyl group reaction catalysts include quaternary salt catalysts such as tetraethylammonium bromide, tetrabutylammonium bromide, tetraethylammonium chloride, tetrabutylphosphonium bromide, triphenylbenzylphosphonium chloride; triethylamine, tributylamine And the like; and the like.

  In the production of the reaction product, the use ratio of the epoxy resin (a1), the rosin (a2) and the fatty acid (a3) is the carboxyl group of the rosin (a2) with respect to 1 equivalent of the epoxy group contained in the epoxy resin (a1). And the sum of the equivalents of the carboxyl groups of the fatty acid (a3) is preferably within a range of 0.9 to 1.1 equivalents, preferably so that no epoxy group remains, the carboxyl groups of the rosins (a2) and It is suitable that the equivalent ratio of the carboxyl group of the fatty acid (a3) is adjusted so that the ratio (a2) / (a3) is within the range of 1/9 to 6/4, preferably 2/8 to 4/6. ing.

  By using the proportions of the epoxy resin (a1), rosin (a2) and fatty acid (a3) within this range, both the initial drying property and the solubility in a weak solvent are compatible, and the degree of freedom in selecting an organic solvent that can be used is increased. It is possible to obtain a wide coating resin composition.

  Subsequently, the polyisocyanate compound (d) is reacted with the hydroxyl group of the reaction product thus obtained until the isocyanate group disappears by heating the polyisocyanate compound (d) to about 70 to 120 ° C. to obtain a rosin-modified epoxy ester resin (A). Manufacturing. At this time, an organic tin catalyst such as dibutyltin dilaurate may be used as necessary.

  The amount of the polyisocyanate compound (a4) used in the polyisocyanate compound (a4) with respect to 1 equivalent of hydroxyl group in the reaction product obtained from the epoxy resin (a1), rosin (a2) and fatty acid (a3). Is selected so that the isocyanate group equivalent is within the range of 0.1 to 0.9 equivalent, particularly 0.4 to 0.8 equivalent, and the coating performance such as the exposed interlayer adhesion and the solubility in weak solvents Suitable from a point.

≪Phenol-modified alkyd resin (B) ≫
In the present invention, the phenol-modified alkyd resin (B) is a resin obtained by modifying an alkyd resin with a phenol resin, and any conventionally known one can be used without limitation. In the present invention, by using the phenol-modified alkyd resin (B) together with the rosin-modified epoxy ester resin (A), the initial drying property of the formed coating film at room temperature can be further improved.

  Examples of the phenol-modified alkyd resin (B) include resins comprising animal and vegetable fats and oils or fatty acids thereof (b1), saturated polybasic acids (b2), polyhydric alcohols (b3), and phenol resins (b4). Can do.

  As animal and vegetable fats and oils or fatty acids thereof (b1), conventionally known ones can be used without any particular limitation, but dry oils are preferably used. For example, fish oil, dehydrated castor oil, safflower oil, flaxseed oil, soybean oil, sesame oil, poppy oil, eno oil, hemp seed oil, grape kernel oil, corn oil, tall oil, sunflower oil, cottonseed oil, walnut oil, rice bran oil, tung oil Or the fatty acid etc. can be mentioned. These can be used alone or in combination of two or more.

  As the polybasic acid (b2), phthalic acid, phthalic anhydride, halogenated phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic acid, hexahydrophthalic anhydride, hexahydroterephthalic acid, hexahydroisophthalic acid, succinic acid , Malonic acid, glutaric acid, adipic acid, sebacic acid, 1,12-dodecanedioic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,3-naphthalene Dicarboxylic acid anhydride, 4,4'-biphenyldicarboxylic acid, and dialkyl esters thereof can be used, and these can be used alone or in combination of two or more.

  Examples of the polyhydric alcohol (b3) include diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 2-methyl-1,3-propanediol, 1,3-butanediol, and neopentyl. Glycol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, bisphenols or adducts of bisphenols and alkylene oxide, 1,2,3,4-tetrahydroxybutane, glycerin, tri Methylolpropane, 1,3-propanediol, 1,2-cyclohexane glycol, 1,3-cyclohexane glycol, 1,4-cyclohexane glycol, 1,4-cyclohexanedimethanol, paraxylene glycol Le, bicyclohexyl-4,4'-diol, 2,6-decalin glycol, 2,7-decalin glycol, etc. These may be used either alone or in combination.

  The phenol-modified alkyd resin (B) can be produced by a conventionally known method. For example, a condensation reaction of animal or vegetable oil or fatty acid (b1), saturated polybasic acid (b2), or polyhydric alcohol (b3). It can manufacture by making a phenol resin (b4) react with the alkyd resin obtained by making it carry out.

  The phenol resin (b4) is used for increasing the molecular weight of the alkyd resin and improving the drying property of the coating film formed using the coating resin composition according to the present invention. Resin can be used without limitation.

  As such a phenolic resin (b4), for example, a resin obtained by reacting phenols with formaldehyde can be used.

  Examples of the phenols include phenol, methylphenol, p-ethylphenol, pn-propylphenol, p-isopropylphenol, pn-butylphenol, p-tert-butylphenol, p-tert-amylphenol, o Phenols having one benzene ring in one molecule such as cresol, m-cresol, p-cresol, p-cyclohexylphenol, p-octylphenol, p-nonylphenol, 3,5-xylenol, resorcinol, catechol; -Phenols having two benzene rings in one molecule such as cresol and p-phenylphenol; bisphenol A, bisphenol F and the like can be mentioned, and these can be used alone or in combination. Examples of formaldehydes include formaldehyde, paraformaldehyde, and trioxane.

  In the present invention, the phenol resin (b4) preferably has a weight average molecular weight in the range of 1,000 to 100,000, particularly 2,000 to 8,000, and the phenol-modified alkyd resin (B) has a solid content. The dryness of the formed coating film and the paint viscosity are such that the mass of the phenol resin (b4) based on 100 parts by mass is in the range of 0.5 to 10 parts by mass, preferably 1.0 to 5.0 parts by mass. It is suitable in terms of

  In this specification, the weight average molecular weight of the resin is the retention time (retention capacity) measured using a gel permeation chromatograph (GPC), based on the retention time (retention capacity) of a standard polystyrene having a known molecular weight measured under the same conditions. It is the value calculated in terms of the molecular weight of polystyrene.

  "HLC-8120GPC" (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and "TSKgel G4000HXL", two "TSKgel G3000HXL", and "TSKgel G2000HXL" are used as columns. A total of four (one product name, all manufactured by Tosoh Corporation) are used, a differential refractometer is used as a detector, mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 mL / min. Can be measured below.

  In order to obtain the phenol-modified alkyd resin (B) by reacting the alkyd resin with the phenol resin (b4), it is considered that the hydroxyl group of the alkyd resin and the methylol group or dimethyl ether group of the phenol resin (b4) are subjected to a condensation reaction. The alkyd resin and the phenol resin (b4) may be mixed, and the reaction temperature may be 120 to 180 ° C. for 1 to 10 hours to cause a heat reaction.

≪Resin composition for coating≫
In the coating resin composition of the present invention, the rosin-modified epoxy ester resin (A) and the phenol-modified alkyd resin (B) are used at a ratio of 70/30 to 10 in A / B in terms of the solid content mass ratio of these two components. Within the range of / 90.
If the ratio of the rosin-modified epoxy ester resin (A) is too low, the viscosity of the paint at a low temperature increases, and the paint becomes unstable. On the other hand, if the ratio of the rosin-modified epoxy ester resin (A) is too large, the initial drying property is inferior.

  The ratio of the rosin-modified epoxy ester resin (A) and the phenol-modified alkyd resin (B) is 50/50 to 10/90, preferably 40/60 to 20/80.

  The coating resin composition of the present invention is not particularly limited, but can be dissolved in a weak solvent, can suppress the lifting phenomenon of the old coating film, and is excellent in initial drying property and adhesion. Therefore, when used as a primer paint, the effect can be maximized.

≪Primer paint≫
The primer paint of the present invention includes pigments such as rust preventive pigments, extender pigments and colored pigments as necessary; organic solvents; modifying resins, thickeners, dispersants, curing agents, curing accelerators, antifoaming agents An additive for paint such as an agent can be blended.

  Of these, phosphoric acid type anticorrosive pigments are suitable as the antirust pigments. Examples of phosphoric acid anticorrosive pigments include magnesium, calcium, zinc, aluminum, or phosphomolybdate compounds of phosphoric acid compounds such as phosphoric acid, phosphorous acid, and polyphosphoric acid, or these What contains 2 or more types of compounds can be utilized. Moreover, what modified these compounds with the silica is also included as a phosphoric acid type anti-rust pigment.

  Also, molybdates and borates such as zinc molybdate and calcium molybdate; metaborates such as barium metaborate; cyanamide zinc calcium; cations such as calcium, zinc, cobalt, lead, strontium and barium It is also possible to use a modified silica in which is bonded to porous silica particles, an ion-exchanged silica by binding a cation by ion exchange; an antirust pigment such as an aluminum pyrophosphate.

  The amount of the rust preventive pigment is generally 5 to 50% by weight, preferably 15 to 25% by weight, based on the resin solid content contained in the primer paint of the present invention. Suitable for corrosion resistance.

  As extender pigments, those known per se can be used, such as silica, barita powder, precipitated barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, white carbon, diatomaceous earth, talc, magnesium carbonate, alumina. Examples thereof include white, gloss white, and tankal, and these can be used alone or in combination of two or more.

  As the coloring pigment, those known per se can be used, and examples thereof include titanium oxide, bengara, cyanine-based coloring pigment, carbon black, zircon powder and the like.

  In addition, the organic solvent contained in the primer paint of the present invention can be conventionally used without limitation depending on the use of the paint composition, but the weak solvent contained in the total organic solvent contained in the paint. It is suitable that the content is 70% by mass or more.

≪Painting method≫
Although it does not restrict | limit especially as a base material surface on which the primer coating material of this invention is coated, For example, metal material surfaces, such as iron, aluminum, and zinc, and its surface treatment surface; Materials, such as concrete, mortar, slate, wood, plastic, stone A surface and a surface-treated surface thereof; and a material surface and an old paint film surface provided on the surface-treated surface.

  The coating can be performed by a general method such as brush coating, spray coating, roller coating, trowel coating, and various coater coatings. Alternatively, a top coat can be applied. As the intermediate coating and top coating, any conventionally known organic solvent-type paint or water-based paint can be applied without any particular limitation. For example, epoxy resin, acrylic resin, urethane resin, acrylic rubber, silicon resin, fluorine Resin-based paints can be mentioned.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples. In the following examples, “part” and “%” mean “part by mass” and “% by mass”, respectively.

≪Production of rosin-modified epoxy ester resin solution≫
Production Example 1
In a reactor having a heating device, a stirrer, and a nitrogen introduction tube, 375 parts of “jER828” (trade name, manufactured by Japan Epoxy Resin, bisphenol A type epoxy resin having an epoxy equivalent of 185), 180 parts of gum rosin, and linseed oil fatty acid 392 parts were charged, heated to 160 ° C. with stirring under a dry nitrogen atmosphere, and reacted until the acid value became 1 or less. Charge 702.5 parts of “Swazole 1000” (trade name, manufactured by Cosmo Oil Co., Ltd., boiling point 162 to 176 ° C.), cool, and then charge 106.8 parts of diphenylmethane-4,4′-diisocyanate until the isocyanate group disappears. The mixture was reacted at 100 ° C. to obtain a rosin-modified epoxy ester resin solution (A-1) having a heating residue of 60%.
Production Example 2
In a reactor having a heating device, a stirrer, and a nitrogen introduction tube, 375 parts of “jER828” (trade name, manufactured by Japan Epoxy Resin, bisphenol A type epoxy resin having an epoxy equivalent of 185), 300 parts of tall rosin, and soybean oil fatty acid 280 parts were charged and heated to 160 ° C. with stirring under a dry nitrogen atmosphere until the acid value was 1 or less. After charging 717.9 parts of “Swasol 1000” (trade name, manufactured by Cosmo Oil Co., Ltd., boiling point: 162 to 176 ° C.), 121.8 parts of tolylene diisocyanate was added and reacted at 100 ° C. until the isocyanate group disappeared. A rosin-modified epoxy ester resin solution (A-2) having a heating residue of 60% was obtained.
Production Example 3
In a reactor having a heating device, a stirrer, and a nitrogen introduction tube, 330 parts of “jER806” (trade name, manufactured by Japan Epoxy Resin, bisphenol F type epoxy resin having an epoxy equivalent of 165), 120 parts of gum rosin, and dehydrated castor oil 448 parts of a fatty acid were charged, heated to 160 ° C. with stirring under a dry nitrogen atmosphere, and reacted until the acid value was 1 or less. "Swasol 1000" (trade name, manufactured by Cosmo Oil Co., Ltd., boiling point: 162 to 176 ° C) is charged with 668 parts, and after cooling, 84 parts of hexamethylene diisocyanate is charged and reacted at 100 ° C until the isocyanate group disappears. A 60% rosin-modified epoxy ester resin solution (A-3) was obtained.

≪Manufacture of modified epoxy resin solution without rosin modification≫
Production Example 4
375 parts of “jER828” (trade name, manufactured by Japan Epoxy Resin Co., Ltd., bisphenol A type epoxy resin having an epoxy equivalent of 185) and 560 parts of soybean oil fatty acid are charged into a reactor having a heating device, a stirrer and a nitrogen introduction tube. The mixture was heated to 160 ° C. with stirring in a dry nitrogen atmosphere and reacted until the acid value became 1 or less. After charging 741.7 parts of “Swazole 1000” (trade name, manufactured by Cosmo Oil Co., Ltd., boiling point 162-176 ° C.) and cooling, 177.6 parts of isophorone diisocyanate was added and reacted at 100 ° C. until the isocyanate group disappeared, A modified epoxy ester resin solution (A-4) having a heating residue of 60% was obtained.

≪Manufacture of rosin-modified epoxy ester resin solution not modified with isocyanate≫
Production Example 5
In a reactor having a heating device, a stirrer, and a nitrogen introduction tube, 375 parts of “jER828” (trade name, manufactured by Japan Epoxy Resin, bisphenol A type epoxy resin having an epoxy equivalent of 185), 180 parts of gum rosin, and soybean oil fatty acid 392 parts were charged, heated to 160 ° C. with stirring under a dry nitrogen atmosphere, and reacted until the acid value became 1 or less. 631 parts of “Swazole 1000” (trade name, manufactured by Cosmo Oil Co., Ltd., boiling point: 162 to 176 ° C.) was charged and cooled to obtain a rosin-modified epoxy ester resin solution (A-5) having a heating residue of 60%.

  In the above production examples 1 to 5, each equivalent ratio of carboxyl groups contained in rosins and fatty acids relative to 1 equivalent of epoxy groups, equivalent ratio of carboxyl groups contained in rosins and fatty acids, of isocyanate groups relative to 1 equivalent of hydroxyl groups in the reaction product The equivalent ratio is shown in Table 1 below.

≪Production of phenol-modified alkyd resin solution≫
Production Example 6
A stirrer, thermometer, 131.7 parts soybean oil, 43.9 parts linseed oil, 46 parts glycerin, 40.8 parts pentaerythritol, 26.7 parts p-tertbutylbenzoic acid, 142.1 parts phthalic anhydride, A four-necked flask equipped with a nitrogen gas inlet tube and an air-cooled tube was charged, and the esterification reaction was advanced at a temperature of 240 ° C. to obtain an alkyd resin. Next, 11 parts of a phenol resin having a weight average molecular weight of 4000 was added, reacted at 150 ° C. for 3 hours, and then diluted with mineral spirits to obtain a phenol-modified alkyd resin solution (B-1) having a solid content of 50%. .

Production Example 7
A phenol-modified alkyd resin solution (B-2) having a solid content of 50% was obtained in the same manner as in Production Example 6 except that the linseed oil was replaced with tung oil in Production Example 6.

Production Example 8
A phenol-modified alkyd resin solution (B-3) having a solid content of 50% was obtained in the same manner as in Production Example 6 except that the weight average molecular weight of the phenol resin was 6000 in Production Example 6.

≪Example of production of phenol-modified alkyd resin solution≫
Production Example 9
In Production Example 6, an alkyd resin solution (B-4) was obtained in the same manner as in Production Example 6 except that modification with a phenol resin was not performed.

≪Manufacture of primer paint≫
Examples 1-7 and Comparative Examples 1-5
The modified epoxy ester resin solution and the alkyd resin solution obtained in the above production examples are mixed with pigments, additives and the like with the composition shown in Table 2, and subjected to a dispersion treatment to produce a primer coating, which is used for the following performance test. did. The compounding amount of the resin is solid mass, and the other components are actual compounding. The results are also shown in Table 2.

(Note 1) “Iron oxide KP-105”: trade name, manufactured by Shin Nippon Metal Chemical Co., Ltd., mainly iron oxide (97% active ingredient) red rust colored pigment,
(Note 2) “Super SS”: trade name, manufactured by Maruo Calcium Co., Ltd., calcium carbonate,
(Note 3) “S talc”: trade name, Nippon Taishi Smelting Co., Ltd., magnesium oxide, extender based on alumina,
(Note 4) “K-White 105”: trade name, manufactured by Teika Co., Ltd., aluminum dihydrogen tripolyphosphate, rust preventive pigment,
(Note 5) “Cobalt naphthenate 5%”: trade name, manufactured by Nikko Materials Co., Ltd., metal dryer,
(Note 6) “UBE MEK oxime”: trade name, manufactured by Ube Industries, Ltd., methyl ethyl ketoxime, anti-skinning agent,
(Note 7) “Dappo SN354”: trade name, manufactured by San Nopco Co., Ltd., antifoaming agent,
(Note 8) “ASA T300-20AK”: trade name, manufactured by Ito Oil Co., Ltd., fatty acid amide wax.

≪Performance Test≫
(* 1) Each paint was applied to an initial drying glass plate with a doctor blade with a gap of 6 mil, and left standing in an environment of 23 ° C. After 4 hours, the dryness of the coating surface was evaluated according to the following criteria.
A: No tack, O: Slight tack remains, but no problem in practical use, Δ: Slight tack remains, x: Paint does not adhere to fingers, but stickiness is remarkable.
(* 2) Suitability for galvanizing Hot-dip galvanized steel sheet (70 × 150 × 3.2 mm, purchased by Partec Co., Ltd.) was degreased with xylene, and each paint was applied with a brush to a coating amount of 130 g / m ² . The next day, “Cera M Retan” (manufactured by Kansai Paint Co., Ltd., urethane resin paint) was applied onto the coated surface with a brush so that the coating amount was 120 g / m ² . After curing at 23 ° C. for 7 days, it was immersed in tap water at 23 ° C. After soaking for 10 days, the coated plate is pulled up, wiped off with a soft cloth and waste cloth, and immediately with a cutter knife in the center of the test piece, a 40 mm long cut reaching the substrate intersecting at an angle of 30 degrees is applied. Next, a cellophane adhesive tape (with a width of 18 mm as defined in JIS Z1522) is applied so that the length of the adhesive part is 50 mm from the top of the two crossed chips, and rubbed with an eraser so that there are no bubbles. The tape is completely attached to the coating film, and within 90 ± 30 seconds after the tape is attached, one end of the tape is kept at right angles to the coating surface, and is peeled off instantaneously, and evaluated according to the following criteria. Went.
◯: No peeling, △: There is peeling in the peripheral part, ×: Full peeling.
(* 3) Low temperature stability The viscosity at 5 ° C. and 23 ° C. of each paint was measured, and the difference was confirmed.
○: No significant difference in viscosity is observed, ×: A significant difference in viscosity is observed
(* 4) Salt spray resistant polished mild steel plate SPCC-SB (70 x 150 x 0.8 mm, purchased by Partec Co., Ltd.) was polished with # 240 sandpaper, degreased with xylene, and applied by brush coating 130 g / m Each paint was applied so as to be ² . After curing for 7 days in an environment of 23 ° C., cutting was made with a cutter knife, the coated plate was placed in a salt spray device in accordance with JIS K5600-7-1, taken out after 240 hours, and evaluated according to the following criteria.
A: There is no rust or swelling.
◯: Very little rust and swelling around the notch.
(Triangle | delta): Rust and a part of swelling are recognized by the notch part periphery.
X: Many blisters are recognized in the whole coating plate.

Claims (7)

A coating resin composition comprising a rosin-modified epoxy ester resin (A) and a phenol-modified alkyd resin (B), wherein the rosin-modified epoxy ester resin (A) has two or more epoxy groups in one molecule. Epoxy resin (a1), rosin (a2), fatty acid (a3), and polyisocyanate compound (a4) having a rosin-modified epoxy ester resin (A) and a phenol-modified alkyd resin The resin composition for coating, wherein the use ratio of (B) is in the range of 70/30 to 10/90 in terms of (A) / (B) solid content mass ratio. In the rosin-modified epoxy ester resin (A), the use ratio of the epoxy resin (a1), the rosin (a2) and the fatty acid (a3) is that of the rosin (a2) with respect to 1 equivalent of the epoxy group contained in the epoxy resin (a1). The sum of the equivalents of the carboxyl group and the carboxyl group of the fatty acid (a3) is in the range of 0.9 to 1.1 equivalents, and the equivalent ratio of the carboxyl group of the rosins (a2) and the carboxyl group of the fatty acid (a3) is The resin composition for coating according to claim 1, wherein the ratio (a2) / (a3) is in the range of 1/9 to 6/4. In the rosin-modified epoxy ester resin (A), the amount of the polyisocyanate compound (a4) used is
The isocyanate group equivalent in (a4) is within the range of 0.1 to 0.9 equivalent to 1 equivalent of hydroxyl group in the reaction product obtained from the epoxy resin (a1), rosin (a2) and fatty acid (a3). The resin composition for coating according to claim 1 or 2, wherein The phenol-modified alkyd resin (B) comprises animal or vegetable oil or fat or fatty acid (b1), polybasic acid (b2), polyhydric alcohol (b3) and phenol resin (b4) as constituent components. The coating resin composition according to any one of the above. The coating resin composition according to claim 4, wherein the amount of the phenol resin (b4) used is in the range of 0.5 to 10 parts by mass based on 100 parts by mass of the solid content of the alkyd resin (B). A primer paint comprising the coating resin composition according to any one of claims 1 to 5. A coating method of coating the primer coating according to claim 6 on a substrate surface.