JP2001019904A - Rustproof paint composition, formation of paint film and painted object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rustproof paint composition enabling pin-holes in forming paint film when a preheated substrate is coated with the composition to be reduced and enabling excellent rustproof paint film to be formed even under a severe condition causing rust due to dew condensation by including a specific rustproofing pigment, a specific hydrophilic organic solvent and a specific vehicle. SOLUTION: This composition comprises (A) a rustproofing pigment obtained by modifying a phosphite of at least one metal selected from the group consisting of Mg, K, Ca, Ba, Zn and Al with a nitride, (B) a hydrophilic organic solvent (e.g. ethylene glycol monobutyl ether) having a boiling point of 160-250 deg.C and (C) a water-soluble or water-dispersible vehicle. A modification quantity of the nitrite in the ingredient A preferably is 1-20 wt.% based on the quantity of the phosphite. The ingredient A preferably is contained in a solid amount of 5-30 wt.% based on the solid weight of the composition. The composition preferably contains (D) an aqueous solution of a nitrite and (E) an adhesion- imparting agent additionally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a rust preventive paint composition,
The present invention relates to a method for forming a coating film and a coated article coated by the method.

[0002]

2. Description of the Related Art In fields where high rust resistance is required, such as steel sheets and steel pipes, a coating film using a rust-preventive paint composition containing a rust-preventive pigment is required. As one of the rust pigments, a chromic acid-based rust preventive pigment is known. Chromic acid-based rust-preventive pigments exhibit excellent performance from the viewpoint of rust-preventive performance, but their use is regulated from the viewpoint of environmental problems. Research has been conducted on non-chromium-based rust-inhibiting pigments as rust-inhibiting pigments that can be replaced with chromic acid-based rust-inhibiting pigments, and various non-chromium-based rust-inhibiting pigments have been proposed.

As such rust preventive pigments and rust preventive paints, JP-A-11-49975 discloses one or two kinds selected from the group consisting of Mg, Ca, Ba, Sr, Zn and Al modified with nitrite. A rust-preventive pigment composition containing the above metal oxyacid salt as a main component and a rust-preventive paint using the rust-preventive pigment are disclosed. To improve painting workability,
The base material is painted in a preheated state. In this case, in the rust-preventive paint, water as a solvent is bumped by the preheating, and a large number of holes are formed in the dried coating film, resulting in poor corrosion resistance under dew condensation conditions. Will be enough.

[0004]

The problem to be solved by the present invention is that when a coating film is formed on a preheated substrate by using a non-chromium-based rust-preventive pigment aqueous paint, water as a solvent is used. However, bumping occurs due to preheating, and a large number of pores are formed in the dried coating film. Even under such severe conditions, rust prevention as a primary rust prevention coating film using no chrome-based rust prevention pigment is obtained. An object of the present invention is to provide a coating composition, a coating film forming method, and a coated product.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned problems, and as a result, have reached the present invention.

[0006] 1. Mg, K, Ca, Ba, Zn or A
l, a rust-preventive pigment obtained by modifying one or more metal phosphites selected from l with nitrite, a hydrophilic organic solvent having a boiling point of 160 to 250 ° C, and a water-soluble or water-dispersible vehicle;
A rust preventive coating composition containing:

[0007] 2. The rust-preventive coating composition as described above, wherein the hydrophilic organic solvent is selected from ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, and diethylene glycol monobutyl ether.

[0008] 3. The rust preventive coating composition as described above, further comprising an aqueous nitrite solution.

4. The rust-preventive coating composition as described above, further comprising an adhesion-imparting agent.

[0010] 5. The rust preventive coating composition as described above, wherein the adhesion imparting agent is an epoxy ester resin.

6. A coating film forming method for forming a rust-preventive coating composition as described above as a primary rust-preventive coating film on a preheated substrate.

7. A coated article coated by the coating film forming method described above.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail.

The rust preventive pigment contained in the rust preventive paint composition of the present invention is Mg,
It is a rust preventive pigment obtained by modifying one or more metal phosphites selected from K, Ca, Ba, Zn or Al with nitrite.

Examples of the metal phosphite include magnesium phosphite, potassium phosphite, calcium phosphite, barium phosphite, zinc phosphite, aluminum phosphite, zinc calcium phosphite, and phosphorous acid Zinc potassium and the like can be mentioned. Among these phosphites, metal salts composed of two or more metals are preferred. Specific examples include zinc calcium phosphite and potassium potassium phosphite.

The above modification with nitrite is carried out by surface treatment. In this surface treatment, nitrite and metal phosphite particles are chemically or physically bonded to each other in a wet or dry manner.

Examples of the nitrite used for modifying the metal phosphite include sodium nitrite, potassium nitrite,
One or more of calcium nitrite, magnesium nitrite, barium nitrite, lithium nitrite, zinc nitrite, aluminum nitrite and the like are mentioned, and preferred are sodium nitrite, potassium nitrite and calcium nitrite. . As the nitrite, either water-containing or anhydrous nitrite can be used.

The amount of denaturation of nitrite is
It is 1 to 20% by weight, preferably 3 to 10% by weight. If the amount is less than 1% by weight, rust prevention performance tends to be poor. On the other hand, if it exceeds 20% by weight, there is a possibility that the water resistance and the paint stability become insufficient.

Content of antirust pigment in antirust paint composition
(Ratio of solid content of pigment to 100 parts by weight of paint solid content: PWC) is preferably 5% to 30%, and more preferably 10% to 2%.
5% is more preferable, and 15% to 20% is still more preferable. If it is less than 5%, the rust prevention performance is poor, and if it exceeds 30%, the appearance of the coating film tends to deteriorate.

Hydrophilic Organic Solvent The rust preventive coating composition of the present invention contains a hydrophilic organic solvent having a boiling point of 160 to 250 ° C. When coating on a preheated base material, water in the solvent remaining in the coating film being formed bumps, and it is presumed that holes are generated as traces of bumping, but this organic solvent is It functions as a coating film forming aid for preventing generation.

As the hydrophilic organic solvent having a boiling point of 160 to 250 ° C., an ether-based hydrophilic organic solvent is preferable, and in particular, ethylene glycol monobutyl ether (boiling point: 171)
° C), ethylene glycol dibutyl ether (boiling point 20
One or more selected from diethylene glycol monomethyl ether (boiling point 194 ° C.), diethylene glycol monoethyl ether (boiling point 203 ° C.), diethylene glycol diethyl ether (boiling point 188 ° C.), diethylene glycol monobutyl ether (boiling point 231 ° C.) Can be mentioned. Preferred are ethylene glycol monobutyl ether and diethylene glycol monobutyl ether. The amount of the hydrophilic organic solvent is preferably 1 to 20 parts by weight with respect to 100 parts by weight of the coating material.
More preferably, it is 5 to 15 parts by weight. When the amount is less than 1 part by weight, the function as a coating film forming aid is insufficient, and a large number of holes may be generated by preheating. When the amount is more than 20 parts by weight, the drying property may be reduced.

Water-soluble or water-dispersible vehicle The water-soluble or water-dispersible vehicle contained in the rust preventive coating composition of the present invention is one or two selected from the above-mentioned Mg, K, Ca, Ba, Zn or Al. A water-soluble or water-dispersible vehicle for dispersing a rust-preventive pigment obtained by modifying at least one kind of metal phosphite with nitrite, comprising a resin for forming a coating film and, if necessary, a crosslinking agent and / or a vehicle component. And an epoxy ester resin as an adhesion imparting agent. The resin used for the coating film forming resin is dissolved or dispersed in a medium containing water and the organic solvent.

Specific resins include, for example, an organic solvent type such as (a) an acrylic resin, (b) a polyester resin, (c) an alkyd resin, (d) an epoxy resin, and (e) a urethane resin, or a water-soluble or aqueous dispersion. (Emulsion) type aqueous type. These can be used in combination of two or more. Acrylic resins and polyester resins are preferred, and acrylic resins are more preferably used. (A) Examples of the acrylic resin include a copolymer of an acrylic monomer and another ethylenically unsaturated monomer. Acrylic monomers that can be used in the copolymerization include methyl, ethyl, propyl, n-butyl and i-acrylic acid or methacrylic acid.
Butyl, t-butyl, 2-ethylhexyl, lauryl,
Esterified products such as phenyl, benzyl, 2-hydroxyethyl and 2-hydroxypropyl, ring-opened adducts of caprolactone of acrylic acid or 2-hydroxyethyl methacrylate, acrylamide, methacrylamide and N
-Methylol acrylamide, acrylic acid, methacrylic acid, itaconic acid, maleic acid, and the like. Other ethylenically unsaturated monomers copolymerizable therewith include styrene, vinyl acetate and the like. When synthesizing an acrylic resin, it is synthesized by copolymerization and emulsion polymerization, and it is usual to use an initiator as an initiator. Examples are inorganic peroxide initiators such as hydrogen peroxide, ammonium persulfate, potassium persulfate, t-butyl hydroperoxide, t-butyl
There are organic peroxide initiators such as amyl hydroperoxide, cumene hydroperoxide, tetralin hydroperoxide, diisopropyl hydroperoxide, and azo-based initiators such as 4,4'-azobis (4-cyanovaleric acid). As the surfactant used for the emulsion copolymerization, a conventional nonionic or anionic surfactant can be used.

(B) Examples of the polyester resin include a saturated polyester resin and an unsaturated polyester resin. Examples thereof include a condensate obtained by heat-condensing a polybasic acid and a polyhydric alcohol. Examples of the polybasic acids include saturated polybasic acids and unsaturated polybasic acids. Examples of the saturated polybasic acids include phthalic anhydride, terephthalic acid, and succinic acid. Examples of the acid include maleic acid, maleic anhydride, fumaric acid and the like. Examples of the polyhydric alcohol include dihydric alcohol and trihydric alcohol, and examples of the dihydric alcohol include ethylene glycol and diethylene glycol.
For example, glycerin, trimethylolpropane and the like can be mentioned. Further, when the vehicle component contains an epoxy ester resin described later, it can function as an adhesion-imparting agent. The resin for forming a coating film includes a curable type and a lacquer type, and a lacquer type is usually used. A type having curability can also be used, but in that case, it is used after being mixed with a crosslinking agent such as an amino resin, a (block) polyisocyanate compound, an amine-based, a polyamide-based, or a polyvalent carboxylic acid. You.

In order to dissolve or disperse the resin in an aqueous medium, the acid value is preferably from 10 to 100, and the acid value is preferably 1 to 1.
If it is less than 0, water solubility and water dispersibility may decrease,
If it exceeds 100, the coating film performance may be reduced. More preferably, it is 20-50. The hydroxyl value is 10-1
If the hydroxyl value is less than 10, the drying property may decrease. If the hydroxyl value exceeds 100, the coating film performance may decrease. More preferably, it is 20-50. The number average molecular weight is preferably from 3,000 to 10,000, and if the number average molecular weight is out of the above range, the coating film performance may be reduced. More preferably 4000 to 800
0.

The acid value of the water-soluble or water-dispersible resin is preferably 10 to 100, more preferably 1 to 100.
5 to 40. The hydroxyl value is preferably 5 to 50, and more preferably 5 to 20. The glass transition temperature (TG) of the paint film of the resin is preferably 15 to 50 ° C., and if it is out of this range, the rust prevention may decrease. More preferably, it is 25 to 40 ° C.

When the vehicle contains a cross-linking agent, the ratio of the resin for forming a coating film to the cross-linking agent is 90 to 50% by weight and the solid content of the cross-linking agent is 10 to 50% by weight in terms of solid content. And preferably, the coating film forming resin is 85 to 60% by weight, and the crosslinking agent is 15 to 40% by weight. When the amount of the crosslinking agent is less than 10% by weight (when the amount of the resin for forming the coating film exceeds 90% by weight), the crosslinking in the coating film is insufficient. On the other hand, when the cross-linking agent exceeds 50% by weight (when the amount of the resin for forming a coating film is less than 50% by weight), the storage stability of the coating composition is lowered and the curing speed is increased.

Aqueous nitrite solution The rust-preventive coating composition of the present invention comprises an aqueous solution of nitrite, which is separate from the nitrite used for the modification of the metal phosphite of the rust-preventive pigment, to provide an anti-rust coating composition. Rustability is further improved. Examples of the nitrite in the aqueous nitrite solution include those used for modifying the rust preventive pigment. Preferred are sodium nitrite, potassium nitrite and calcium nitrite. The compounding amount of the nitrite aqueous solution is preferably 0.05 to 2 parts by weight, more preferably 0.1 to 1 part by weight as nitrite, based on 100 parts by weight of the paint. 0.05
If the amount is less than part by weight, the function as long-term rust prevention performance may be insufficient, and if it exceeds 2 parts by weight, water resistance may decrease.

Adhesion-imparting agent The rust-preventive coating composition of the present invention contains an adhesion-imparting agent, whereby the adhesion between the coating film and the substrate is improved, and the rust-prevention performance is further improved. As the adhesion-imparting agent, a water-soluble or water-dispersible epoxy ester resin is preferable. In this case, the epoxy resin is a vehicle component as described above. The epoxy ester resin is obtained by adding and condensing an epoxy resin and a fatty acid by a known method.

Examples of the epoxy resin include a resin obtained by a reaction between bisphenol and epichlorohydrin. As bisphenol, for example,
Bisphenol A, F and the like can be mentioned. As the bisphenol-type epoxy resin, for example, Epicoat 82
8, epicoat 1001, epicoat 1004, epicoat 1007, epicoat 1009 (all manufactured by Shell Chemical Co., Ltd.), and those obtained by chain-extending these with an appropriate chain extender can also be used. Among these bisphenol type epoxy resins, when used as an aqueous type resin, Epicoat 1001 and Epicoat 1004 (both manufactured by Shell Chemical Co., Ltd.) are preferable from the viewpoint of excellent water dispersibility and drying property. Epoxy resins are used alone or in combination of two or more. The epoxy equivalent of these epoxy resins is not particularly limited. Fatty acids include dry fatty acids, semi-dry oils, and fatty acids derived from non-drying oils, such as tung oil fatty acids, linseed oil fatty acids, soybean oil fatty acids, castor oil fatty acids, dehydrated castor oil fatty acids, safflower oil fatty acids, and tall oil. Fatty acids, coconut oil fatty acids and the like, linoleic acid, linolenic acid, oleic acid and the like, and synthetic fatty acids such as versatic acid and the like can be mentioned. These can be used alone or in combination of two or more. In order to impart room temperature curability, it is preferable to use a fatty acid derived from a drying oil or a semi-drying oil. The blending amount of the adhesiveness-imparting agent is preferably from 2 to 20 solid parts by weight, more preferably from 5 to 15 solid parts by weight, based on 100 parts by weight of the paint. When the amount is less than 2 parts by weight, the function as a long-term anticorrosive property may be insufficient due to insufficient adhesion, and when it exceeds 20 parts by weight, the drying property may be reduced.

Ingredients Other than the Above The rust preventive coating composition of the present invention may contain a coloring pigment and an extender pigment in addition to the above components. Examples of such pigments include those conventionally used for paints.Examples of organic pigments include, for example,
Azo lake pigments, phthalocyanine pigments, indico pigments, perylene pigments, quinophthalone pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, metal complex pigments, and the like.Inorganic pigments include, for example, , Yellow iron oxide, red iron oxide, titanium dioxide,
Examples of the extender include talc, clay, and calcium carbonate. In addition,
When the rust-preventive pigment and, if necessary, the color pigment and extender are used, the total content (PWC) of the pigment as a whole is 50%.
-75% is preferable, and 60-70% is more preferable. 5
If it is less than 0%, the drying property may be reduced, and if it exceeds 75%, the appearance of the coating film is reduced.

Further, a sedimentation inhibitor, a curing catalyst, an ultraviolet absorber, an antioxidant, and a leveling agent which are a polyamide wax which is a lubricating dispersion of an aliphatic amide and a polyethylene wax which is a colloidal dispersion mainly composed of polyethylene oxide. , Surface modifiers such as silicon and organic polymers, surfactants, dispersants, anti-sagging agents, thickeners, defoamers, fungicides,
An antiseptic, a lubricant, a crosslinkable polymer particle (microgel), and the like can be appropriately contained. The performance of paints and coatings can be improved by blending these additives at a ratio of 20 parts by weight or less to 100 parts by weight of the paint.

The rust preventive coating composition of the present invention is obtained by dissolving or dispersing the above-mentioned constituents in water or a solvent containing water and an organic solvent. Examples of the organic solvent used in combination with water include aromatic hydrocarbon solvents, alcohol solvents and the like in addition to the above-mentioned hydrophilic organic solvents.

The film forming method of a coating film forming method of the present invention, 70 to the anticorrosive coating composition
After coating on a base material preheated to 110 ° C. to form a primary rust-preventive coating film, it may be stored outdoors or in a warehouse or the like, and repair painting may be performed when necessary.

The rust-preventive coating composition of the present invention is a primary rust-preventive coating composition having good rust-preventive properties, particularly when stored outdoors or in a warehouse, especially in severe conditions in which the substrate is subject to condensation. A film can be formed.

The substrate is not limited, and includes metals such as iron, aluminum, copper and alloys thereof, and can be applied to plate-like substrates and processed substrates. . The base material may be subjected to a treatment such as degreasing, blasting or chemical conversion as necessary.

The method of applying the rust preventive coating composition on a substrate is not particularly limited, but a spray method, a roll coater method and the like are preferable. Regarding the number of times of coating, one coating or multiple coatings may be used.

Coated product The coated product of the present invention is obtained by the above-mentioned coating film forming method. The dry film thickness of the primary rust-preventive coating film coated with the rust-preventive coating composition is 10 to 50 μm per coat. Preferably
20 to 40 μm is more preferable.

As a primer and a top coating applied to the primary rust-preventive coating film of the present invention as required, those generally used for metal coating can be used. A mixture of at least one resin selected from polyester resins, alkyd resins, fluorine resins, epoxy resins, polyurethane resins, polyether resins, and modified resins thereof, and, if necessary, the above-mentioned crosslinking agent. be able to. Also,
These primers, top coatings, if necessary, color pigments and extenders and modifiers, UV absorbers,
Additives such as leveling agents, dispersants and defoamers can be included.

[0040]

EXAMPLES Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the compounding amount represents a weight part unless there is particular notice.

Examples 1 to 18 and Comparative Examples 1 to 4 Preparation of Substrates Black scale steel sheet (length 150 mm, width 70 mm and thickness 4 m)
m) was subjected to a solvent degreasing treatment to obtain a substrate.

Preparation of Rust Preventive Paint Composition Rust preventive pigment, coloring pigment (iron oxide coloring pigment / carbon black = 97/3: weight ratio), extender pigment to epoxy ester having a number average molecular weight of 4,500 and an acid value of 40 (Calcium carbonate / talc = 40/60: weight ratio) and a dispersible amount of pure water were mixed and dispersed in the types and ratios shown in Table 1. Next, the emulsion resin, the remaining pure water, the hydrophilic organic solvent having a boiling point of 160 to 250 ° C. in the type and ratio shown in Table 1 and an additive (surfactant / dispersant / antifoaming agent) are added together with an additive (surfactant / dispersant / antifoaming agent) by a stirrer to obtain a proper viscosity. To prepare a rust-preventive coating composition. When an aqueous solution of sodium nitrite was contained, it was mixed and stirred with the above additives. When not containing the epoxy ester,
The rust-preventive pigment, the coloring pigment, the extender and the dispersible amount of pure water were blended in the types and ratios shown in Table 1 and dispersed. Next, the emulsion resin, the remaining pure water, and the above-mentioned hydrophilic organic solvent in the type and ratio shown in Table 1 were stirred together with additives (surfactant / dispersant / antifoaming agent) by a stirrer so as to obtain an appropriate coating viscosity. The mixture was mixed to prepare a rust preventive coating composition.

[0043]Formation of primary rust preventive coating A base material maintained at a preheating temperature of 85 ° C. is coated with the above rust-preventive coating composition.
The product is dried with water so that the dry film thickness becomes 15 μm and 25 μm.
Coating was performed separately at the same dry film thickness. Painting is a spray painting machine
("Wider 77", manufactured by Iwata Paint Co., Ltd.)
Formation pressure 3kg / cm ^TwoI went in. Booth atmosphere during painting
Was maintained at a temperature of 25 ° C. and a humidity of 75%. Preheating to room temperature
The heat was released for 1 hour and used as a test plate. The resulting coating
Was evaluated by the following evaluation method. Table 1 shows the evaluation results.
Show.

Evaluation method Rust prevention: Each test plate having a dry film thickness of 15 μm and 25 μm was (1) cooled at 5 ° C. for 5 hours.
12 hours in a humid condition of 00%, this is one cycle,
The rusting area S due to dew condensation after 5 cycles was visually evaluated. 5 ... S = 0% 4 ... 0 <S≤1% 3 ... 1% <S≤5% 2 ... 5% <S≤10% 1 ... 10% <S

[0045]

[Table 1]

[0046]

According to the present invention, one or more metal phosphites selected from Mg, K, Ca, Ba, Zn or Al are modified with nitrite on a preheated substrate. The rust preventive pigment and the rust preventive paint composition in which a hydrophilic organic solvent having a boiling point of 160 to 250 ° C. is used in combination with an aqueous vehicle to form a coating film. The number of holes at the time of formation was reduced, and a favorable rust-preventive coating film could be formed even under severe conditions of rusting due to dew condensation. Incidentally, the primary rust-preventive coating film obtained by the present invention, a good rust-prevention property is obtained even under the dew condensation condition on the substrate on which the film is formed,
It is preferably used for various processed steel materials.

Claims (7)

[Claims] An anti-corrosion pigment obtained by modifying one or more metal phosphites selected from Mg, K, Ca, Ba, Zn or Al with nitrite, and having a boiling point of 160 to 250 ° C. A rust preventive coating composition containing an organic solvent and a water-soluble or water-dispersible vehicle. 2. The method according to claim 1, wherein the hydrophilic organic solvent is selected from ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, and diethylene glycol monobutyl ether. Antirust paint composition. 3. The rust preventive coating composition according to claim 1, further comprising an aqueous nitrite solution. 4. The method according to claim 1, further comprising an adhesion-imparting agent.
The rust-preventive coating composition according to any one of Items 1 to 3. 5. The rust-preventive coating composition according to claim 4, wherein the adhesion-imparting agent is an epoxy ester resin. 6. A method for forming a rust-preventive coating composition according to claim 1 on a preheated substrate as a primary rust-preventive coating film. 7. A method according to claim 6, wherein said film is formed by said method.
The painted object described.