JPS6141266B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for forming a coating film having excellent properties such as moisture resistance, water resistance and rust prevention. More specifically, a solvent-based undercoat paint composition is first applied onto an object to be coated, dried to form an undercoat film, and then a solvent-free paint composition containing a scale pigment on the paint film. The present invention relates to an anticorrosive coating method with excellent moisture resistance and other properties, which comprises applying an intermediate coating, drying to form a cured coating, and then topcoating with a solvent-free top coating composition. Conventionally, various types of tanks, bridges, land steel structures, pipes, etc. require long-term protection, so various solvent-based paint compositions, oil-based paint compositions, etc. have been combined in various ways, and undercoats and topcoats have been applied. being done. For example, considering the selectivity of topcoat paint over basecoat paint, oil-based paint / phenolic resin paint / chlorinated rubber paint, organic or inorganic zinc-rich paint / chlorinated rubber paint, epoxy resin paint / It is painted with a combination of polyurethane resin paint, epoxy resin paint/epoxy resin paint, etc. However, even if the object is coated with such a coating system, it may be exposed to harsh environments where water droplets or ice film are constantly present, such as penstocks in hydroelectric power plants, or submerged in water such as in water gates. In such an environment, the coated object could not be effectively protected for a long period of time by the coating film. In other words, penstocks with cold water constantly flowing inside the pipes have condensation on their outside surfaces at all times, except during the winter, or are submerged in water, so the paint film may swell within 6 to 15 months after painting. This was easy to occur, and as a result, degeneration progressed at the same time. On the other hand, with the rapid rise in labor costs for painting, there is a desire for a highly durable paint that can be repainted for a long time, that is, protects the object being coated from corrosion over a long period of time. By the way, it is commonly accepted that corrosion of iron occurs when water and oxygen exist simultaneously on the surface of the substrate. Therefore, it is understood that protection with a coating film can be achieved for a long period of time by blocking or reducing the permeation rate of any one of the above-mentioned components that enter through the coating film. As a result of studying various coating systems from the above viewpoint, the present inventors did not change the undercoat much in the conventional coating system, but rather changed the intermediate coating. By using a solvent-free coating composition containing a pigment and using a resin composition with low oxygen permeability, and using a similar solvent-free coating composition as a top coat, the moisture resistance of the coating film can be improved. The present invention has been achieved based on the discovery that various performances such as water resistance and rust prevention can be further improved. It should be noted that the usual intermediate coating compositions used in conventional coating systems are those that have a somewhat lower extender pigment content than the undercoat compositions and have good interlayer adhesion and topcoat finish. Ta. In addition, among conventional paint systems, oil-based and/or alkyd resin-based primer paints - Micaclous
In the coating system, phenolic resin intermediate coating containing lron oxide (hereinafter abbreviated as MIO) and chlorinated rubber top coating, an intermediate coating containing scale-like pigment is used. However, in this case, applying the top coat directly onto the base coat will cause lifting, so to prevent this,
In addition, since the intermediate coat contains MIO, its surface becomes uneven, improving the adhesion of the top coat, and as a result, the interval between top coats can be extended. It was hardly possible to improve the moisture resistance, water resistance, rust prevention, etc. of the coating film as intended by the present invention. In other words, since MIO-containing phenolic resin paint is a solvent-based paint, when the solvent scatters,
MIO becomes an obstacle and is difficult to scatter, and even if the solvent does scatter, it tends to result in a coating film with a porous structure.Therefore, it is expected that the moisture resistance, water resistance, rust prevention, etc. of a single film will improve. was actually difficult. Furthermore, an MIO-containing epoxy resin intermediate coating paint is considered for the epoxy resin coating system, but this coating is not much different from the aforementioned intermediate coating paint. Furthermore, in conventional coating systems, even if a topcoat paint is specified, a coating system with an optimal combination has not been substantially obtained from the viewpoint of selectivity to the undercoat paint, interlayer adhesion, etc. The present invention has been made for the purpose of eliminating or improving various drawbacks of the prior art as described above. In other words, by using a specific intermediate coating composition and top coating composition, a coating film with extremely low oxygen permeability can be formed, and it can be used for a long period of time.
No paint film defects such as rust or blisters occur.
Moreover, the present invention aims to provide a method for forming a coating layer that has excellent adhesion to non-coated paints and has excellent overall performance such as moisture resistance, water resistance, and rust prevention. . That is, the present invention comprises: (i) a step of undercoating a solvent-based coating composition on an object to be coated and drying to form an undercoat film; (ii) a step of containing a scaly pigment on the paint film; a step of applying a room temperature curable solvent-free coating composition capable of radical polymerization and oxidative polymerization as an intermediate coating, and forming a cured coating film by polymerization, and (iii) applying a radical polymerizable and oxidative polymerizable composition on the intermediate coating film The present invention relates to an anticorrosive coating method comprising the steps of: applying a topcoat with a room temperature curable solvent-free coating composition and forming a cured coating film by polymerization. The undercoating solvent-based composition used in the present invention is one in which the vehicle is diluted with a volatile organic solvent, such as oil-based paint compositions, solvent-based alkyd resin-based paint compositions, and solvent-based epoxy resins. Examples include solvent-based polyurethane resin-based paint compositions, solvent-based chlorinated rubber-based paint compositions, and solvent-based vinyl resin-based paint compositions. These may be used alone or in a mixture of two or more. More specifically, the oil-based coating composition uses boiled oil such as tung oil or soybean oil, or a composition in which part of it is replaced with petroleum resin, alkyd resin, etc., as a color vehicle. In addition, the alkyd resin coating composition includes oil or its fatty acid,
The color vehicle is a resin obtained by a known esterification reaction between a polyhydric alcohol and a polycarboxylic acid or its anhydride. The reaction temperature for the esterification is 150 to 280°C, and the reaction is performed while the generated water is successively removed. The end point of the esterification reaction is determined by measuring the amount of water produced by the esterification reaction or the acid value. From the viewpoint of coating film performance, the acid value at the end of the reaction is preferably 50 or less. Examples of the oil or fatty acid used for producing the alkyd resin include oils such as castor oil, cottonseed oil, dehydrated castor oil, linseed oil, safflower oil, soybean oil, and tung oil, and fatty acids thereof. The amount of the oil or fatty acid used is preferably 5 to 70% by weight of the total formulation for producing the alkyd resin. In addition, examples of the polyhydric alcohol used in the production of the alkyd resin include ethylene glycol, diethylene glycol, trinitylene glycol, propylene glycol, dipropylene glycol, butanediol 1.3, butanediol 1.4, butanediol 2. 3, bentanediol 1.5, hexanediol 1.6, neobentyl glycol, 2.2.4-trimethylbentanediol-1.3, hydrogenated bisphenol A,
2,2-di(4-hydroxybropoxyphenyl)bropane, glycerin, bentaerythritol diallyl ether, trimethylene glycol,
2-ethyl-1,3-hexanediol, trimethylolbropane, cyclohexanedimethanol-
Contains 1,4,2,2,4-tetramethylcyclobutanediol-1,3,1,4-bis(2-oxyethoxy)benzene, 2,2,4,4-tetramethylcyclobutanediol-1,3, etc. These can be used alone or as a mixture. Furthermore, saturated or unsaturated polycarboxylic acids or their acid anhydrides used in the production of alkyd resins include maleic acid, fumaric acid, itaconic acid,
Citraconic acid, mesaconic acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, hettic acid, 3,6-endomethylene Tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, methylnadic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, anthracene-maleic anhydride adduct, rosin-maleic anhydride adduct, etc. These can be used alone or as a mixture. Other known monocarboxylic acids and the like can also be used in combination, if desired. Furthermore, a modified alkyd resin obtained by polymerizing the alkyd resin with a polymerizable monomer described below can also be used. Furthermore, the epoxy resin coating composition used in the present invention is a composition containing an epoxy resin having at least two or more epoxy groups in one molecule and an amino curing agent as a color vehicle. Examples of the epoxy resin include (1) those synthesized by the reaction of bisphenol A and epichlorohydrin or methylepichlorohydrin, such as Epicote #827, #828, #1001 manufactured by Yuka Ciel Epoxy Co., Ltd.;
#1004, #1007, #1009, etc.; Union Carbide product name ERL #2772, #2774,
EKR2002 etc.; Ciba product name: Araldite
GY-#250, #260, #280, #6071, #6084,
#6099, etc.; product name DER #330 manufactured by Asahi Kasei Corporation,
#331, #332, #661, #664, etc.; trade name Epicron #800 manufactured by Dainippon Ink & Chemicals Co., Ltd.;
#1000, #4000, etc.; (2) Those synthesized by reacting glycols with epichlorohydrin or methylepichlorohydrin, such as the product name manufactured by Dow Chemical Co.
DER#736, etc.; (3) Novolaks or resols obtained by reacting phenols and formaldehyde under an acidic or alkaline catalyst and epichlorohydrin or methylepichlorohydrin, such as products manufactured by Dow Chemical Company. given name
DEN #431, #438, #448, etc.; Ciba product name ECN #1235, #1273, #1280, #1290, etc.; (4) Those synthesized by oxidizing intramolecular double bonds,
For example, the product names manufactured by Union Carbide Co., Ltd. include UNOTS #201, #206, #207, #221, #289;
Product name: Araldite CY#175, manufactured by Ciba.
#176, etc., product name Oxiron #2001, #2002, etc. manufactured by FMC, USA; (5) Products obtained by reacting halogenated phenols with epichlorohydrin or methylepichlorohydrin, for example, product name manufactured by Dow Chemical Company DER #511, #542, #580, etc.; Ciba product name: Araldite #8011, #8047, etc.; (6) Reacting phenols with ethylene oxide or propylene oxide, etc., and epichlorohydrin or methylepichlorohydrin. For example, Asahi Denka
(7) Those obtained by reacting carboxylic acid with epichlorohydrin or methylepichlorohydrin, such as the product name AK manufactured by Nippon Kayaku Co., Ltd.
#737, #838, etc., manufactured by Showa Denko Co., Ltd. under the trade name Syodyne #508, #540, #550, etc., Dainippon Ink & Chemicals Co., Ltd. under the trade name Epicron #200,
Examples include #300, #400, #500, etc. These can be used alone or as a mixture. Furthermore, it should be noted that epoxy compounds and derivatives of the above-mentioned epoxy resins that can be easily inferred from these compositions are also included within the scope of the present invention. For example, polyol-type epoxy resins, fat-reduced epoxy resins, halogen-containing epoxy resins, and the like are included. Alternatively, in order to improve workability, coating performance, and coating condition, if necessary, a mononiboxy compound having one epoxy group may be used in combination with the epoxy resin in an amount of up to 20% by weight. Examples of such compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, methyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, styrene oxide, cyclohexene oxide, and epichlorohydrin. Furthermore, in addition to the above, melamine resins, urea resins, phenol resins, hydrocarbon resins (such as polybutadiene), alkyd resins, polyester resins, maleated oils, urethanized oils, vinyl tar, asphalt, and the like may be used in combination. In the present invention, as the amino compound as a curing agent for the epoxy resin, amino compounds such as amine adduct, polyamide, and polyamine are used alone or as a mixture. In order to carry out a cross-linking reaction with the above-mentioned epoxy resin, these need to have at least two or more nitrogen atoms and an active hydrogen bonded to them in one molecule. Examples of the amino curing agent used in the present invention include: As polyamide resins, commonly available commercially available products such as Tomide Y-25 and Tomide Y-25, manufactured by Fuji Kasei Kogyo Co., Ltd.
245, 2400, 2500; Daiichi Zeoral Co., Ltd., product name: Xenamide 2000, Versamide 115, 125, DSX
−1280; Manufactured by Sanwa Chemical Co., Ltd., trade name Sanmide 320,
Epicure 330; manufactured by Yuka Ciel Epoxy Co., Ltd., product name Epicure 3255, Epicure 4522. Amine adduct resin manufactured by Fuji Kasei Kogyo Co., Ltd.
Manufactured by, product name: Tomide 238, Fujiki Your #202,
#5000: Manufactured by Asahi Denka Co., Ltd., trade name: ADEKA HARDENER
EH-212, EH-220, EH-240, EH-531 Examples of heterocyclic diamine derivatives include products such as Epomate B-002, Epomate C-002, and Epomate S005 manufactured by Ajinomoto Co., Inc. These curing agents may be used singly or as a mixture of two or more depending on the purpose. The polyurethane resin coating composition used in the present invention is a one-component type, a two-component type, or a moisture-curing type obtained by using a hydroxyl group-containing compound, an isocyanate group-containing compound, and, if necessary, a modifier. This is a composition that uses a polyurethane resin such as a mold as a color vehicle. Therefore, the one-component polyurethane resin contains a polyhydric alcohol compound having two or more hydroxyl groups in one molecule and, if necessary, various active hydrogen-containing compounds such as phenol type, alcohol type, active methylene type, mercabutan. Compounds such as acid amide, imide, amine, imine, imidazole, urea, carbamate, oxime, and sulfite compounds (generally called blocking agents), and isocyanate group-containing compounds. can be obtained by reacting in a conventional manner. Furthermore, two-component polyurethane resin is a two-component composition consisting of a polyisocyanate compound containing two or more isocyanate groups in one molecule and a compound containing two or more active hydrogen groups in one molecule. This is obtained as follows. Furthermore, moisture-curable urethane resins are obtained from polyisocyanate compounds having two or more isocyanate groups in one molecule. In the present invention, it is also possible to use the one-component, two-component, and moisture-curable urethane resins modified by conventional methods. Examples of the polyhydric alcohols mentioned above include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexanediol, neobentyl glycol, hexanetriol, trimethylolpropane, glycerin, castor oil, and pentaerythritol. Examples of compounds containing two or more active hydrogen groups include polyester, polyether, and hydroxyl group-containing acrylic resin. Further, as the polyisocyanate compound, 2,4-tolylene diisocyanate, 2,6
-tolylene diisocyanate, 1,6-hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, trans-cyclobutane-1,2-bismethylisocyanate, 1,3-
Phenyl diisocyanate, isopropylidene bis(4-phenyl isocyanate), bis(4
-Isocyanate phenyl) sulfone, 4,4'-
Diphenyl ether diisocyanate, bisphenylene diisocyanate, 3,3'-dimethyl-
4,4'-phenylene diisocyanate, cyclohexylmethane-4,4'-diisocyanate, xylylene diisocyanate, 2,4-cyclohexylene diisocyanate, or reaction products of excess of these isocyanate compounds with polyhydric alcohols. I can do it. These can be used alone or as a mixture of two or more. Examples of the blocking agent include phenol, cresol, methanol, cyclohexanol, dimethyl malonate, butylmercabutane, thiophenol, acetanilide, acetaniside, succinimide, diphenylamine, 2-ethylimidazole, urea, thiourea, N- Examples include phenyl phenylcarbamate, ethyleneimine, formaldoxime, methyl ethyl ketoxime, and sodium bisulfite. The chlorinated rubber coating composition used in the present invention is commercially available, for example, from Sanyo Kokusaku Pulp Co., Ltd. Product name Super Chron CR10, CR20
Compositions containing chlorinated rubber as the main color vehicle are used. The chlorinated rubber can also be used in combination with chlorinated paraffins, epoxy resins, alkyd resins, and the like. Furthermore, the vinyl resin coating composition uses a resin obtained by copolymerizing the following polymerizable monomers as a color vehicle. The polymerizable monomers include, for example, styrene, methylstyrene, chlorostyrene, tertiarybutylstyrene, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.
Acrylate, lauryl (meth)acrylate,
β-Hydroxyethyl (meth)acrylate, β
-Hydroxypropyl (meth)acrylate, 4
-Hydroxybutyl (meth)acrylate, monoester of (meth)acrylic acid of glycerol trimethylolpropane, glycidyl (meth)acrylate, N-butoxymethyl (meth)acrylamide, N-tertiarybutyl (meth)acrylamide, dimethyl Aminoethyl (meth)acrylate, diacetone acrylamide, vinylpyrrolidone, N-methylol acrylamide, acrylamide, (meth)acrylic acid, crotonic acid, vinyl acetate, vinyl chloride, (meth)acrylonitrile, ethylene glycol mono( Examples include meth)acrylates and derivatives thereof. These may be used alone or as a mixture of two or more. In addition, the various color vehicles used in the present invention may include extender pigments such as talc, barium sulfate, calcium carbonate, barite powder, titanium oxide, zinc white, scaly oxide, etc., as necessary. Coloring pigments such as iron, yellow lead, chromium oxide, ultramarine blue, phthalocyanine blue, carbon black, and iron black; metal powders such as aluminum and zinc; reinforcing pigments such as glass fiber, glass flakes, mica powder, asbestos, and synthetic silica; Rust pigments, other thickeners, rust preventives, antifoaming agents, anti-settling agents, hardening accelerators, chelation reaction accelerators, concomitant resins, etc. can be added. In the method of the present invention, the above-mentioned solvent-based undercoating paint composition is first applied onto a surface to be coated after cleaning the surface or onto a surface to which a shovel primer or the like has been applied in advance. Then, it is dried at room temperature or by forced drying. Painting methods include brush painting, spray painting,
General methods such as airless painting can be applied. The dry film thickness of the undercoat is preferably about 30 to 200 microns. On the other hand, the room temperature curable, solvent-free coating composition capable of radical polymerization and oxidative polymerization as an intermediate coating or top coating containing the scale pigment used in the present invention includes (A) sorbic acid; An oil-modified alkyd resin with an oil length of 30 to 70% modified with an α/β-unsaturated monocarboxylic acid selected from crotonic acid and 2-(β-furyl)acrylic acid (however, α/β-unsaturated monocarboxylic acid Acid content is 0.5-30% by weight)
......30 to 70% by weight, and (B) a polymerizable monomer that dissolves component (A)
Most preferred is a composition in which a curing catalyst is blended into a resin component consisting of 70 to 30% by weight. Such a composition can be cured by drying at room temperature or accelerated drying, and has excellent moisture resistance, water resistance, rust prevention, as well as surface smoothness, hardness, bending resistance, impact resistance, etc. Gives a coating. To explain further, the component (A), that is, the oil-modified alkyd resin modified with an α/β-unsaturated monocarboxylic acid, has the following characteristics, except that it is modified with a specific α/β-unsaturated monocarboxylic acid. It is essentially the same as conventional oil-modified alkyd resin. Furthermore, the method of modification with α/β-unsaturated monocarboxylic acid is carried out in the same manner as the method of modifying ordinary alkyd resin with fatty acid. As the polybasic acid component of the alkyd resin,
Phthalic anhydride, isophthalic acid, tetrahydrophthalic anhydride, adipic acid, sebacic acid, azelaic acid, having a side chain obtained by the Diels-Alder addition reaction between various conjugated double bond-containing isobrene dimers and maleic anhydride. 1, 2, 3, 6-
Tetrahydrophthalic anhydride derivatives, such as mircel maleic anhydride, alloocimene maleic anhydride, 3-(β-methyl-2-butenyl)-5-methyl-1,2,3,6-tetrahydrophthalic acid,
Aromatics such as hexahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, trimellitic acid,
One or a mixture of two or more aliphatic or alicyclic saturated polybasic acids may be used. A portion of the saturated polybasic acid may be replaced with an unsaturated polybasic acid, such as maleic acid, maleic anhydride, fumaric acid, itaconic acid, etc., as long as gelation does not occur. Particularly preferred among the saturated polybasic acids are phthalic acid and 3-(β-methyl-2-butenyl)-5-
It is a combination with methyl-1,2,3,6-tetrahydrophthalic anhydride (hereinafter abbreviated as MBTHP). When MBTHP is used as part of the polybasic acid, it has a remarkable effect on lowering the viscosity of alkyd resins. In addition, in the above, the polyhydric alcohol component of the alkyd resin includes ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol,
One or a mixture of two or more of neobentyl glycol, glycerin, bentaerythritol, trimethylolpropane, trimethylolethane, tris(2-hydroxyethyl) isocyanurate, etc. is used. Generally, dihydric or trihydric alcohols having about 2 to 12 carbon atoms are used. Examples of the fat or fatty acid forming the alkyd resin include air-drying fats and oils such as linseed oil, soybean oil, tall oil, and safflower oil, or fatty acids separated therefrom. The oil-modified alkyd resin is further modified with an α/β-unsaturated monocarboxylic acid. The α·β-unsaturated monocarboxylic acid is crotonic acid, sorbic acid or 2-(β-furyl)acrylic acid. Particularly preferred is sorbic acid. The α/β-unsaturated monocarboxylic acid exists in the alkyd resin skeleton and contributes to curing through radical copolymerization with component (B), so it has a great effect on improving the hardness and water resistance of the resulting coating film. . The α/β-unsaturated monocarboxylic acid, fatty acid,
Oil-modified alkyd resins can be obtained from polybasic acids and polyhydric alcohols by conventional methods, but from the viewpoint of preventing gelation during the reaction, fatty acids, polybasic acids, and polyhydric alcohols are first reacted, and then α and β
- Most preferred is a production method in which an unsaturated monocarboxylic acid is reacted. Furthermore, in order to avoid gelation during the reaction, it is desirable to add an antigelation agent such as hydroquinone. The oil-modified alkyd resin has an oil length of 30 to 70
%, preferably 55-65%. If the oil length is less than 30%, the water resistance of the coating film tends to decrease, while if it exceeds 70%, it may lead to insufficient hardness in the early stage of drying and a decrease in surface smoothness. Further, the α/β-unsaturated monocarboxylic acid content in the α/β-unsaturated monocarboxylic acid-modified oil-modified alkyd resin is 0.5 to 30
% by weight, more preferably in the range 2-15% by weight. In the above, the α/β-unsaturated carboxylic acid content is
If it is less than 0.5% by weight, the water resistance, hardness, etc. of the coating film will decrease, and if it exceeds 30% by weight, it will tend to gel during the reaction. The acid value of the α/β-unsaturated monocarboxylic acid-modified oil-modified alkyd resin is about 15 to 40. The polymerizable monomer that dissolves the alkyd resin thus obtained is particularly preferably a monomer containing at least one radically polymerizable ethylenically unsaturated bond and having a boiling point of 200°C or higher. Specific examples of such monomers are as follows. Monoacrylates or methacrylates of monohydric or polyhydric alcohols having 2 to 20 carbon atoms, preferably 2 to 18 carbon atoms, such as 2-hydroxyethyl (meth)
Acrylate, 2-hydroxybropyl (meth)
Acrylate, 2-hydroxyethoxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxybentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, neopentyl glycol mono(meth)acrylate, 3 -Butoxy-2-
Hydroxypropyl (meth)acrylate, 2-
Hydroxy-1 or 2-phenylethyl (meth)acrylate, polypropylene glycol monomethacrylate, glycerin mono(meth)acrylate monohalf maleate, diethylene glycol mono(meth)acrylate, cyclohexyl (meth)acrylate, pendyl (meth)acrylate, 2-ethoxy Ethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate,
Tetrahydrofurfuryl (meth)acrylate, etc.; having at least 2 hydroxyl groups and having 2 or more carbon atoms
20, preferably 2 to 6 polyhydric alcohols, preferably dihydric to tetrahydric alcohols, and di, tri or tetraesters of acrylic acid or methacrylic acid,
For example, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylol Propantry (Meta)
Examples include acrylate, bentaerythritol tetra(meth)acrylate, glycerin monoacrylate monomethacrylate, etc.; relatively low boiling point styrene, methyl methacrylate, divinylbenzene, etc. Particularly preferred are tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, 3-butoxy-2-hydroxypropyl acrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane tri(meth)
It is acrylate. These monomers may be used alone or as a mixture of two or more. The blending ratio of the α/β-unsaturated monocarboxylic acid-modified oil-modified alkyd resin and the polymerizable monomer is:
It is preferable to use the resin at a ratio of 30 to 70% by weight: 70 to 30% by weight, preferably 40 to 60% by weight, taking the resin content of both as 100 to be 60 to 40% by weight. In the above range, if the amount of the former exceeds 70% by weight, the composition becomes highly viscous, leading to a decrease in coating workability, while if it is not 30% by weight, the water resistance of the coating film deteriorates.
Impact resistance, bending resistance, etc. tend to decrease. In the present invention, the composition comprising the oil-modified alkyd resin and the polymerizable monomer includes coloring pigments such as titanium oxide, carbon black, iron oxide, and ultramarine, and extender pigments such as talc, zinc white, and barium sulfate. , anticorrosion pigments such as red lead, zinc powder, and zinc chromate, paint film surface property improvers such as polyethylene glycol,
Additives such as fillers, stabilizers, pigment dispersants, thixotropes, silane coupling agents, anti-skinning agents, etc. can be added. Furthermore, the solvent-free coating composition used in the present invention is
Curing can be carried out by using a curing catalyst, ie, a redox catalyst consisting of an organic peroxide and a reducing agent, and, if necessary, a metal drier such as manganese naphthenate or cobalt naphthenate. Examples of the curing catalyst include (1) a combination of methyl ethyl ketone peroxide and cobalt naphthenate, (2) a combination of a redox catalyst consisting of benzoyl peroxide and dimethylaniline and cobalt naphthenate or manganese naphthenate, (3) cyclohexanone Examples include a combination of peroxide and cobalt naphthenate. In particular, cobalt naphthenate is suitable because it not only participates in radical generation as a reducing agent but also acts as a metal dryer that participates in the oxidative hardening of the oil-modified alkyd resin. The above-mentioned various curing catalysts are used in a ratio of about 0.5 to 5 parts by weight of organic peroxide and 0.01 to 5 parts by weight of reducing agent to 100 parts by weight of the total of oil-modified alkyd resin and polymerizable monomer. is preferable. In the coating method of the present invention, when a solvent-free coating composition is used as an intermediate coating, flaky pigments are essential. As the scale pigment,
For example, flaky iron oxide, glass flakes, aluminum powder, talc, mica, etc. are used. These may be used alone or as a mixture of two or more. Further, the intermediate coating composition includes a resin content of 30 to 90% by weight consisting of the oil-modified alkyd resin and the polymerizable monomer, and 70 to 10% by weight of the flaky pigment.
It is preferred to use a composition consisting of % by weight. In the above, when the amount of flaky pigment is less than the lower limit, the desired effect of the present invention tends to decrease. On the other hand, if the amount exceeds the upper limit, the smoothness of the surface tends to be easily impaired, which is not preferable. As already explained, the coating film forming method of the present invention includes:
After the intermediate coating solvent-type paint composition is applied to the object to be coated and dried, the intermediate coating solvent-free coating composition is applied thereon by a known general coating method such as brush coating, air spray coating, airless coating, etc. The dry film thickness is approximately
30 to 500μ, preferably in the range of 40 to 350μ, and then further apply the above-mentioned top coat solvent-free paint composition by a known general painting method such as brush painting, air spray painting, airless painting, etc.
The dry film thickness is approximately 30 to 500 mm.
It consists of various steps of making the particle size about μ, preferably in the range of 40 to 350 μ. The solvent-free coating composition is cured by radical polymerization and oxidative polymerization during the drying process to form a coating film. Thus, according to the method of the present invention, the following effects can be achieved. (1) It is possible to form a coating film with excellent interlayer adhesion, no prister formation, and excellent corrosion resistance. (2) A coating film with excellent pre-star resistance can be obtained. (3) It has no selectivity to the undercoat paint and has excellent lifting properties. (4) The oxygen permeability of the paint film is very low. For example, the oxygen permeability of the film formed from the intermediate coat and top coat of the present invention is approximately 1/10 to 1/1 that of the chlorinated rubber coating.
It is about 100. (5) Since the intermediate coating and top coating compositions are solvent-free coatings, thick film coating is possible. Since the various effects described above can be exhibited, the industrial utility value of the present invention is necessarily great. Hereinafter, the present invention will be explained in detail with reference to Examples. In addition, "parts" or "%" in each example indicate "parts by weight" or "% by weight." () Preparation of solvent-based undercoat paint composition (i) Oil-based paint composition for undercoat (A) 34.0 parts of linseed oil boiled oil and Bengara color pigment
6.0 parts, calcium carbonate 52.3 parts, mineral spirits 4.0 parts, anti-skinning agent 0.2 parts, metal dryer 2.5 parts and thixotropic agent 1.0 parts,
Knead with a roller and add 23.5% of lead zinc oxide powder during use.
Parts were mixed to obtain an oil-based paint composition (A). (ii) Solvent-type alkyd resin coating composition for undercoat (B) 35.0 parts of soybean oil-modified alkyd resin (oil length 65%, non-volatile content 70%, viscosity at 20°C 55 Stokes Poise), linseed oil/soybean oil boiler Oil 5.0 parts, Bengara coloring pigment 13.0 parts, calcium carbonate 3.5 parts, anti-skinning agent 0.2 parts, thixotropic agent 1.0
and 2.5 parts using a mixing dryer were kneaded using a roller, and 26.6 parts of zinc oxide powder was added at the time of use to obtain a solvent-type alkyd resin coating composition (B). (iii) Solvent-based epoxy resin coating composition for undercoating
(C) (Main agent) 70% xylene solution of solid bisphenol A-based epoxy resin (epoxy equivalent: 450-500)
30.0 parts, liquid bisphenol A-based epoxy resin (epoxy equivalent 230-270) 3.0 parts, talc
40.0 parts, Bengara coloring pigment 5.0 parts, thixotropic agent 1.0
10.0 parts of xylene, 10.0 parts of cellosolve, and 1.0 part of additives were kneaded with a roller to form a main ingredient. (Curing agent) Modified heteroalicyclic polyamine (amine value 87mg
A curing agent was prepared by dissolving 50.0 parts of KOH/g) in 50 parts of xylene. When using, base agent and hardening agent are 80:20 (weight ratio)
A solvent-type epoxy resin coating composition (C) was obtained. (iv) Solvent-borne polyurethane resin coating composition for undercoat (D) (Main ingredient) Castor oil 5.0 parts, trimethylolpropane
1.0 part, hydroxyl group-containing solid bisphenolic epoxy equivalent weight 450-500, 70% xylene solution)
30.0 parts, methyl isobutyl ketone 6.0 parts, talc 45.0 parts, Bengara coloring pigment 5.0 parts, thixotropic agent
2.4 parts of xylene and 5.6 parts of xylene were kneaded with a roller to form a main ingredient. (Curing agent) 50 parts of 4,4'-diphenylmethane diisocyanate solution (NCO content 31%) was mixed with 50 parts of methyl isobutyl ketone to prepare a curing agent. The base agent and curing agent were mixed at a ratio of 80:20 (weight ratio) at the time of use to obtain a solvent-type polyurethane resin coating composition (D). (v) Solvent-type chlorinated rubber paint composition for undercoating (E) Chlorinated rubber [CR-10 manufactured by Sanyo Kokusaku Pulp Co., Ltd.]
10.0 parts, chlorinated paraffin 4.0 parts, modified alkyd resin (oil length 50%, non-volatile content 50%) 6.0
part, thixotropic agent 1.0 parts, xylene 9.0 parts, talc
70.0 parts were kneaded with a roller to obtain a solvent-type chlorinated rubber coating composition (E). (vi) Solvent-type vinyl resin coating composition for undercoat (F) 40.0 parts of a mixed solution of vinyl acetate-methacrylic acid ester copolymer in methyl isobutyl ketone and xylene (nonvolatile content 50%, viscosity at 20°C 25 Stokes Poise), 40 parts of talc, 2.0 parts of thixotropic agent, 8.0 parts of methyl isobutyl ketone, 8.0 parts of xylene, and 2.0 parts of additives were kneaded with a roller to obtain a solvent-based vinyl resin coating composition (F). () Preparation of a room-temperature curable solvent-free coating composition capable of radical polymerization and oxidative polymerization for intermediate coating (i) Solvent-free coating composition for intermediate coating (A) Stirrer, water separator, cooler, and nitrogen gas In a four-neck flask equipped with an inlet, 52.9 parts of soybean oil fatty acid, 14.9 parts of phthalic anhydride,
After charging 11.7 parts of MBTHP, 5.5 parts of glycerin, and 15.1 parts of bentaerythritol, and further adding 0.1 part of hydroquinone and 4.0 parts of xylene, a reaction was carried out at 220°C in a nitrogen stream. When the acid value of the alkyd produced reached 40, 7.1 parts of sorbic acid and hydroquinone were added.
0.2 part was added and the reaction was continued until the acid value reached 20, resulting in a sorbic acid content of 7.1% and oil length.
A 55.3% oil-modified alkyd resin (a) was obtained. 10.0 parts of 2-hydroxypropyl acrylate and 35.0 parts of 1,4-butanediol diacrylate were added to 55.0 parts of the oil-modified alkyd resin.
and stir until the viscosity is 1.6 poise (25℃)
A resin composition was obtained. This resin composition 98.0
parts, cobalt naphthenate (metal content 6%) 0.98
After stirring and mixing 0.15 parts of methyl ethyl ketone oxime, 0.001 part of silicone antifoaming agent, and 0.4 parts of asbestos thixotropic agent, 1.7 parts of methyl ethyl ketone peroxide and 66.4 parts of aluminum paste were added immediately before use to form a solvent-free coating composition ( A) was obtained. (ii) Solvent-free paint composition for intermediate coating (B) 56.5 parts of dehydrated castor oil fatty acid, phthalic anhydride
15.0 parts, MBTHP 11.9 parts, glycerin 6.7 parts,
The above alkyd resin except that 13.5 parts of pentaerythritol and 3.5 parts of crotonic acid were used.
The reaction was carried out in exactly the same manner as in (a) to obtain an oil-modified alkyd resin having a crotonic acid component content of 3.5% and an oil length of 59.0%. To 55.0 parts of the oil-modified alkyd resin, 10.0 parts of 2-hydroxyprovinyl acrylate, 1.4 parts
-Butanediol diacrylate (35.0 parts) was added and stirred to dissolve, thereby obtaining a solvent-free resin composition having a viscosity of 2.3 poise (25°C). 25.0 parts of the solvent-free resin composition, 0.25 parts of cobalt naphthenate (metal content 6%), 4.0 parts of talc.
part, 0.4 part of methyl ethyl ketone oxime, 0.001 part of silicone antifoaming agent, and organic thixotropic agent
After kneading 0.8 parts with a roller, 70.0 parts of M10 was added and mixed, and 1.0 parts of methyl ethyl ketone peroxide was added immediately before use to obtain a solvent-free coating composition (B). (iii) Solvent-free paint composition for intermediate coating (C) 54.6 parts of dehydrated castor oil fatty acid, phthalic anhydride
15.1 parts, MBTHP 12.0 parts, glycerin 7.7 parts,
12.1 parts of pentaerythritol and 2-(β
An oil-modified alkyd with an acid value of 20, a content of 2-(β-furyl)acrylic acid of 5.4%, and an oil length of 57.1% was prepared in exactly the same manner as the alkyd resin (a) except that 5.4 parts of -furyl)acrylic acid was used. Resin was obtained. To 55 parts of the oil-modified alkyd resin, 10.0 parts of 2-hydroxypropyl acrylate, 1.4 parts
-35.0 parts of butanediol acrylate was added, stirred and dissolved to obtain a solvent-free resin composition having a viscosity of 2.5 poise (25°C). 75.0 parts of the solvent-free resin composition, 4.0 parts of titanium oxide, 0.9 parts of cobalt naphthenate, 0.1 part of methyl ethyl ketone oxime, and a silane coupling agent [trade name KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.]
After adding 0.5 part of silicone antifoaming agent, 0.001 part of silicone antifoaming agent, and 0.5 part of organic thixotropic agent and kneading with a roller, 23.0 parts of glass flakes (150 mesh) were added and stirred. A solvent-free coating composition (C) was obtained. () Preparation of comparative intermediate coating composition (i) Comparative intermediate coating composition (D) Commercially available non-water dispersible acrylic alkyd resin (non-volatile content 50%, viscosity Gardner Z) 30.0
part, talc 10.0 parts, mineral spirits 9.0 parts
After kneading with a roller 0.4 parts of organic thixotropic agent, 0.2 parts of methyl ethyl ketone oxime, and 0.6 parts of cobalt naphthenate (metal content 5%),
50.0 parts of M10 and 3.0 parts of mineral spirits were added and stirred to obtain a comparative intermediate coating composition (D). (ii) Comparative intermediate coating composition (E) 70% xylene solution of solid bisphenol A-based epoxy resin (epoxy equivalent: 450-500)
After kneading with a roller 25.0 parts, 16.0 parts of talc, 3.0 parts of Bengara, 1.0 parts of an organic thixotropic agent, 13 parts of xylene, 5 parts of ethyl cellosolve, and 3.0 parts of methyl isobutyl ketone, 4.5 parts of MIO was added and stirred. It was used as the main ingredient. On the other hand, modified heteroalicyclic polyamine (solid content
65%, amine value 165) was dissolved in 30 parts of xylene to prepare a curing agent. At the time of use, the main agent and curing agent were mixed at a ratio of 90/10 (weight ratio) to obtain a comparative intermediate coating composition (E). () Preparation of solvent-free coating composition for top coating (i) Coating composition for top coating () In a four-necked flask equipped with a stirrer, water separator, cooler and nitrogen gas inlet, soybean oil fatty acid 52.9 parts, 14.9 parts of phthalic anhydride,
MBTHP 11.7 parts, glycerin 5.5 parts and pentaerythritol 15.1 parts and xylene 4.0 parts
After adding 50% of the solution, the reaction was carried out at 220°C in a nitrogen stream. When the acid value of the alkyd produced reached 40, 7.1 parts of sorbic acid and hydroquinone were added.
0.2 part was added and the reaction was continued until the acid value reached 20, resulting in a sorbic acid content of 7.1% and oil length.
A 55.3% oil-modified alkyd resin (b) was obtained. 10.0 parts of 2-hydroxypropyl acrylate and 35.0 parts of 1,4-butanediol diacrylate were added to 55.0 parts of the oil-modified alkyd resin.
and stir until the viscosity is 1.6 poise (25℃)
A resin composition was obtained. To 65.0 parts of the composition, 10.0 parts of barium sulfate, 5.0 parts of talc, and 20.0 parts of titanium oxide were mixed, and a silicone antifoaming agent was added.
0.001 part, asbestos-based thixotropic agent 0.4 part, cobalt naphthenate (metal content 6%) 0.65 part, and methyl ethyl ketone oxime 0.12 part to prevent skinning and adjust pot life, and mix with a roller before use. At the same time, 1 part of methyl ethyl ketone peroxide was added to obtain a solvent-free top coating composition (). (ii) Top coating composition () 56.5 parts of dehydrated castor oil fatty acid, phthalic anhydride
15.0 parts, MBTHP 11.9 parts, glycerin 6.7 parts,
The reaction was carried out in exactly the same manner as alkyd resin (b) except that 13.5 parts of pentaerythritol and 3.5 parts of crotonic acid were used to determine the crotonic acid component content.
An oil-modified alkyd resin of 3.5% and oil length of 59.0% was obtained. To 55.0 parts of the oil-modified alkyd resin, 10.0 parts of 2-hydroxypropyl acrylate, 1.
35.0 parts of 4-butanediol diacrylate was added and dissolved with stirring to obtain a solvent-free resin composition having a viscosity of 2.3 poise (25°C). 65 parts of this composition, 3.0 parts of talc, barium sulfate
10.0 parts, calcium carbonate 3.0 parts, titanium oxide
20.0 parts, cobalt naphthenate (metal content 6%)
0.65 parts, methyl ethyl ketone oxime 0.11
After adding 0.001 part of a silicone antifoaming agent and 0.4 part of an asbestos thixotropic agent and performing roller kneading, 1.5 parts of methyl ethyl ketone peroxide was added at the time of use to obtain a solvent-free top coating composition (). . (iii) Top coating composition () 54.6 parts of dehydrated castor oil fatty acid, phthalic anhydride
15.1 parts, MBTHP 12.0 parts, glycerin 7.7 parts,
12.1 parts of pentaerythritol and 2-(β
-Furyl) React in exactly the same manner as alkyd resin (b) except for using 5.4 parts of acrylic acid,
An oil-modified alkyd resin having an acid value of 20, a 2-(β-furyl)acrylic acid content of 5.4%, and an oil length of 57.1% was obtained. To 55 parts of the oil-modified alkyd resin, 10.0 parts of 2-hydroxypropyl acrylate, 1.4 parts
35.0 parts of -butanediol diacrylate was added, stirred and dissolved to obtain a solvent-free resin composition having a viscosity of 2.5 poise (25°C). 65 parts of this composition, 10.0 parts of talc, barium sulfate
5.0 parts, titanium oxide 20.0 parts, cobalt naphthenate (metal content 6%) 0.7 parts, methyl ethyl ketone oxime 0.09 parts, silicone antifoaming agent
After adding 0.001 part and 0.3 part of an asbestos-based thixotropic agent and kneading with a roller, 1 part of methyl ethyl kentone peroxide was added at the time of use to obtain a solvent-free top coating composition (). () Preparation of comparative top coat composition (i) Comparative top coat composition () Mineral spirit solution of modified soybean oil alkyd resin (oil length 60%, non-volatile content 70%) 40.0
parts, titanium oxide 25.0 parts, barium sulfate 25 parts,
Anti-skinning agent 0.4 parts, mixed dryer 2.0 parts
part, 1.3 parts of additives and mineral spirits
6.3 parts were kneaded with a roller to obtain a comparative top coating composition (). (ii) Comparative top coat composition () (Main ingredient) 28.0 parts of bisphenol A type epoxy resin (epoxy equivalent: 450-500), 12 parts of xylene, 30.0 parts of talc, 10.0 parts of barium sulfate, 5.5 parts of titanium oxide, ethyl 10.0 parts of Cellosolve, 1.5 parts of a thixotropic agent, and a leveling agent were kneaded with a roller to obtain a base ingredient. (Curing agent) Modified heteroalicyclic polyamine (solid content 65%,
A curing agent was obtained by dissolving 70 parts of amine value (165) in 30 parts of xylene. At the time of use, the main agent and curing agent were mixed at a ratio of 87/13 (weight ratio) to obtain a comparative top coating composition (2). Examples 1 to 6 and Comparative Examples 1 to 4 (1) Preparation of test pieces First, an undercoat paint composition was applied to a sandblasted steel plate (1.6 x 70 x 150 mm) using air according to the coating system shown in Table 1. After spray painting to the specified dry film thickness, store at room temperature (20℃)
I left it for 2 days. Next, an intermediate coating composition was applied thereon in the same manner and left at room temperature for 2 days. Subsequently, a top coating composition was applied in the same manner, and after being left at room temperature for 7 days, it was subjected to a comparative test. The results are shown in Table 1. (2) Test method (i) Humidity resistance: 49 Tests were conducted at 1°C and 97% RH or higher, and the time until blistering occurred was determined. (ii) Water resistance: The entire surface was immersed in pure water at room temperature, and the time until blister formation was measured. (iii) Rust prevention: After making a cross cut that reached the substrate on the coated surface of the test piece, a salt spray test (JIS-K-544, 7, 8) was conducted to observe the state of rust on the test piece. .

【table】

[Table] The coating film formed by the method of the present invention uses a solvent-free coating composition with excellent corrosion resistance and low oxygen permeability as an intermediate coating composition and a top coating composition. It is clear from the table that this coating system has much better properties such as moisture resistance, water resistance, and rust prevention than the other coating systems.

Claims (1)

[Scope of Claims] 1 (i) A step of undercoating a solvent-based coating composition on an object to be coated and then drying to form a coating film; (ii) Radical polymerization and oxidation containing the flaky pigment. A step of applying a polymerizable room temperature curable solvent-free coating composition as an intermediate coating and polymerizing it to form a cured coating film, and (iii) a step of applying thereon a room temperature curable solvent-free coating composition that is capable of radical polymerization and oxidative polymerization. Topcoat with a mold paint composition,
An anticorrosive coating method comprising the steps of polymerizing to form a cured coating film. 2. The solvent-based coating composition for undercoating includes oil-based coating compositions, alkyd resin-based coating compositions, epoxy resin-based coating compositions, polyurethane resin-based coating compositions, chlorinated rubber-based coating compositions, and vinyl resin-based coating compositions. The anti-corrosion coating method according to claim 1, wherein the anti-corrosion coating method is selected from the following. 3. The room-temperature curable intermediate-coat, solvent-free coating composition containing a flaky pigment and capable of radical polymerization and oxidative polymerization is composed of ()(A) sorbic acid, crotonic acid and 2-(β
−Frill)α・β− selected from acrylic acid
Oil length 30-70 modified with unsaturated monocarboxylic acid
% of oil-modified alkyd resin (however, α and β
-Unsaturated monocarboxylic acid content is 0.5 to 30% by weight) ...30 to 70% by weight and (B) a polymerizable monomer that dissolves component (A)
A composition consisting of a resin content of 70 to 30% by weight, a resin component of 30 to 90% by weight, () a scale pigment 70 to 10% by weight, and () a required amount of curing catalyst. , the anticorrosive coating method according to claim 1. 4. Claims 1, 2, or 4, wherein the scaly pigment is one or a mixture of two or more selected from glass flakes, scaly iron oxide, aluminum powder, talc, and mica. The anticorrosive coating method according to item 3. 5. The above-mentioned solvent-free paint composition capable of radical polymerization and oxidative polymerization for top coating is curable at room temperature, and (A) contains an α/β-union selected from sorbic acid, crotonic acid, and 2-(β-furyl)acrylic acid. Oil-modified alkyd resin with an oil length of 30 to 70% modified with a saturated monocarboxylic acid (however, the α/β-unsaturated monocarboxylic acid content is 0.5 to 30% by weight)
......30 to 70% by weight and (B) a polymerizable monomer that dissolves component (A)
The anticorrosive coating method according to claim 1, 2, 3, or 4, wherein the composition is a composition in which a curing catalyst is blended into a resin component consisting of 70 to 30% by weight.