JPH11158436A - Primer composition for precoated metal, method for forming coating film, and coated object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a primer composition which can give a precoated metal improve in anticorrosiveness in an edge, a cut part and a processed part and being excellent in scratch resistance. SOLUTION: 100 pts.wt. (in terms of the solids content) curable resin composition containing a film-forming resin (a) and a curing agent (b) comprising 10-100 pts.wt., per 100 pts.wt. (in terms of the solid content) above film-forming resin, amino resin and/or blocked isocyanate is incorporated with 1-150 pts.wt. at least one chromate rust-preventive pigment (c), 0.5-100 pts.wt. rust-preventive pigment based on a phosphite powder (d), and 0.1-50 pts.wt. ion exchanger inorganic powder whose anions or cations are ion-exchanged (e). To further improve the scratch resistance, the composition may further contain 1-30 pts.wt. inorganic substance particles and/or 0.5-10 pts.wt. organic polymer particles (f).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a primer composition to be applied as a primer on a precoated metal,
The present invention relates to a method for forming a coating film of the primer composition and a coated product.

[0002]

2. Description of the Related Art Galvanized steel sheets, zinc-base alloy-coated steel sheets, and aluminum-galvanized steel sheets have been widely used as durable steel sheets. These are used in a wide range of fields, including building roofing materials, wall materials, and various home appliances.

[0003] These coated steel sheets are subjected to a chemical conversion treatment such as a zinc phosphate treatment or a chromate treatment.
It is often used as a so-called pre-coated metal by applying a primer and further applying a top coat.
The pre-coated metal is a metal plate that is formed into a predetermined shape by performing a process such as bending after coating and coating on a steel plate or the like. In these pre-coated metals, the coating film may be blistered at a cut surface, a cut portion, a flaw portion, or the like of the painted product, and rust (red rust, white rust, etc.) resulting therefrom may be generated. This is considered to occur because the steel sheet is corroded and the coating is pushed up by corrosion products, water, hydrogen gas and the like. Such corrosion is remarkable especially in an aluminum / zinc alloy-plated steel sheet, and a countermeasure has conventionally been desired.

As a method for solving the above problems, for example, Japanese Patent Application Laid-Open No. Sho 58-120784 discloses a primer using a chromate pigment having high water solubility and a chromate pigment having low water solubility in combination. JP-A-59-14942 discloses a primer-coated steel sheet in which an aluminum / zinc alloy-plated steel sheet contains a strontium chromate pigment or a calcium chromate pigment at a concentration of 30 to 70% by weight based on the nonvolatile residue of the primer. Is disclosed. Japanese Patent Application Laid-Open No. 6-9902 discloses a primer using a chromate pigment in combination with a pigment obtained by complexing vanadate or vanadium pentoxide with phosphate. However, even when such a primer was used, the corrosion resistance at the cut surface or cut portion was still insufficient.

[0005] On the other hand, as described above, it is premised that the pre-coated metal is subjected to various types of processing. However, when the pre-coated metal is subjected to the processing, the film is liable to be scratched. Often decreased. As a method for improving such scratch resistance, Japanese Patent No. 2524886 discloses a method for improving scratch resistance by adding inorganic fine particles, silica and organic polymer particles to a primer. However, in such a primer composition, although scratch resistance is improved, since inorganic or organic polymer particles having a relatively large particle diameter are used, a gap is formed in the coating film, and water and corrosive substances are permeated. However, there is a problem that white rust and red rust are easily generated on end faces such as cut surfaces, although blisters are hardly generated on the flat surface portion of the coating film.

A first object of the present invention is to provide a primer composition for a precoated metal capable of improving the corrosion resistance of an end face, a cut portion, and a processed portion of a precoated metal, a method for forming a coating film using the same, and a coated product. To provide.

A second object of the present invention is to provide a primer composition for a pre-coated metal capable of obtaining a pre-coated metal having excellent scratch resistance, a method for forming a coating film using the same, and a coated product. is there.

[0008]

The primer composition for a precoated metal according to the first aspect of the present invention comprises (a) a film-forming resin and (b) 100 parts by weight of a solid content of the film-forming resin. (C) at least one chromate-based rust preventive pigment based on 100 parts by weight of the solid content of the curable resin composition containing 10 to 100 parts by weight of an amino resin and / or a curing agent comprising a blocked isocyanate compound; 150 parts by weight, (d) 0.5 to 100 parts by weight of a rust preventive pigment containing phosphite powder as a main component, and (e) 0.1 to 100 parts by weight of an ion-exchange inorganic powder obtained by ion exchange of anions or cations. 50 parts by weight of a primer composition for a precoated metal.

According to the first aspect of the present invention, it is possible to enhance the corrosion resistance of the end face, the cut portion, and the processed portion. The primer composition for a precoated metal according to the second aspect of the present invention comprises: (a) a film-forming resin; and (b) 10 to 100 parts by weight of a solid content of the film-forming resin.
(C) at least 1 part by weight based on 100 parts by weight of a solid content of a curable resin composition containing 100 parts by weight of an amino resin and / or a curing agent comprising a blocked isocyanate compound;
1 to 150 parts by weight of a kind of chromate-based rust-preventive pigment, and (d)
Rust preventive pigment containing phosphite powder as a main component 0.5 to 100
Parts by weight, and (e) 0.1 to 50 parts by weight of an ion-exchange inorganic powder obtained by ion-exchange of anions or cations;
(F) A primer composition for a precoated metal, comprising 1 to 30 parts by weight of inorganic substance particles and / or 0.5 to 10 parts by weight of organic polymer particles.

[0010] According to the second aspect of the present invention, it is possible to obtain a pre-coated metal having improved corrosion resistance at the end face, the cut portion, and the processed portion, and also having excellent scratch resistance. Hereinafter, the first aspect and the second aspect of the present invention will be described.
Each component of the primer composition for a precoated metal according to the above aspect will be described.

Film-forming resin (a) As the film-forming resin in the present invention, a thermoplastic resin or a thermosetting resin can be used. As the thermosetting resin, for example, epoxy resin, epoxy urethane resin, modified epoxy resin, phenoxy resin, phenol resin, acrylic resin, acrylic epoxy resin, acrylic phenol resin, acrylic phenol epoxy resin, polyester resin, modified polyester resin, alkyd Examples of the film-forming resin include resins, isocyanate-curable acrylic resins, urethane resins, and acid anhydride-modified polypropylene resins. Of these, epoxy resins, phenol resins and polyester resins are particularly preferred, and one or more of these can be used.

As the thermoplastic resin, chlorinated polyolefin resins such as chlorinated polyethylene and chlorinated polypropylene, vinyl chloride resin, vinyl acetate resin, vinylidene chloride, which are commonly used in the field of coatings, and copolymers thereof are used. Vinyl resin, cellulose resin, acetal resin, chlorinated rubber resin and the like. When a thermoplastic resin is used as the film-forming resin (a) in the present invention, the curing agent (b) may not be used.
Therefore, the first aspect of the present invention comprises the components (a), (c),
A primer composition for a precoated metal containing (d) and (e). Further, a second aspect of the present invention is a primer composition for a pre-coated metal, comprising the components (a), (c), (d), (e), and (f).

The form of the resin can be used irrespective of solvent type or aqueous. As a curing method, active energy ray curing can be used in addition to heat curing. When an epoxy resin and a phenol resin are used, a primer excellent in adhesion to zinc plating, zinc-based alloy plating, aluminum-zinc alloy plating, aluminum, stainless steel, and the like, and furthermore, corrosion resistance can be obtained. When a polyester resin is used, a primer having excellent bending workability can be obtained. These resins can be used alone or in combination of two or more.

The glass transition point (Tg) of the film-forming resin used in the present invention is from 0 to 70 ° C. When workability is important, use a polyester resin
g is more preferably 0 to 30 ° C. More preferably 5-
20 ° C. The number average molecular weight is 500 to 30,000.
It is preferably 0, and the hydroxyl value is preferably 5 to 300.

Curing Agent (b) The curing agent used in the present invention is a curing agent for the film-forming resin (a), and an amino resin and / or a blocked isocyanate compound is used in accordance with the resin used.

The amino resin is not particularly limited.
For example, melamine resin, guanamine resin, glycoluril resin, urea resin, and the like can be given. The melamine resin is classified into a high imino-type alkyl etherified melamine resin, a methylol type alkyl etherified melamine resin, an alkyl etherified melamine resin, a mixed alkyl etherified melamine resin, and the like. It can be appropriately selected according to the temperature and the physical properties of the coating film. Since those having an imino group or a methylol group generally have low water resistance, alkyl etherified melamine resins and mixed alkyl etherified melamine resins are preferred from the viewpoint of water resistance of the coating film.

Examples of the alkyl etherified melamine resin include a butylated melamine resin etherified by an n-butyl group and an i-butyl group, a methylated melamine resin etherified by a methyl group, and a methyl group, an n-butyl group. Methyl etherified with a butyl group and an i-butyl group /
There are butyl mixed etherified melamine resins. Commercially available methylated melamine resins include, for example, those having a methoxy / isobutoxy group molar ratio of 60/4.
Cymel 238 having a molar ratio of methoxy / butoxy groups of 60/40, Cymel 231 having a molar ratio of methoxy / butoxy groups of 65/35, and Cymel 231 having a molar ratio of methoxy / butoxy groups of 40/60. Cymel 236,
Symar 266, 267 (manufactured by Mitsui Cytec) and Sumimar 50B (manufactured by Sumitomo Chemical Co., Ltd.) having a methoxy group / butoxy group molar ratio of 70/30.

Commercially available butylated melamine resins include, for example, Mycoat 506 (manufactured by Mitsui Cytec), Uban 20SE (manufactured by Mitsui Toatsu Chemicals), and Uban 20N-60 (manufactured by Mitsui Toatsu Chemicals). Manufactured).

Commercially available methylated melamine resins include, for example, Cymel 303 (manufactured by Mitsui Cytec), Sumimar M30W, M40S, M5
0W (manufactured by Sumitomo Chemical Co., Ltd.) and Melan 622 and 623 (manufactured by Hitachi Chemical Co., Ltd.).

Examples of the guanamine resin include commercially available products such as Cymel 1123, 1128, and Mycoat 105 (benzoguanamine resin, manufactured by Mitsui Cytec).

Examples of the glycoluril resin include commercially available products such as Cymel 1170, 1171 and 1172 (manufactured by Mitsui Cytec). Examples of the urea resin include commercially available products such as UFR65 and 300 (manufactured by Mitsui Cytec).

When the amino resin is used as the curing agent (b), the amount of the amino resin may provide an equivalent or more of the amino group to the hydroxyl value of the film-forming resin (a). Any amount is possible as long as it is possible. Usually, the weight ratio of [film-forming resin (a)] / [amino resin] is 100/10 to 100/100. Preferably 100/10 to 100/50, more preferably 10/10
0/25 to 100/50.

When the amino resin is used as the curing agent (b), it is preferable to use a catalyst which promotes the reaction with the film-forming resin (a). As the catalyst, an acid catalyst is used, and examples thereof include aromatic sulfonic acids such as dodecylbenzenesulfonic acid, paratoluenesulfonic acid, and dinonylnaphthalenesulfonic acid and salts thereof; organic phosphates; organic phosphonates; Can be. Of these, aromatic sulfonic acids and amine salts of aromatic sulfonic acids are preferred. As the counter cation of these acid catalysts, amines are preferred.

The amount of the acid catalyst is usually 0.5 to 3 parts by weight based on 100 parts by weight of the total of the film-forming resin (a) and the amino resin. If it is less than 0.5 parts by weight, curability is reduced, and only a soft coating film is obtained,
Not only the hardness but also the acid resistance, alkali resistance, and stain resistance are reduced. If it exceeds 3 parts by weight, the effect corresponding to the added amount cannot be obtained.

The above-mentioned blocked isocyanate compound is an isocyanate compound in which a reactive group is blocked by a suitable blocking agent. The blocked isocyanate compound is not particularly limited as long as it is a compound having at least two isocyanate groups in one molecule, and examples thereof include aliphatic diisocyanates such as hexamethylene diisocyanate (HMDI) and trimethylhexamethylene diisocyanate (TMDI). Alicyclic diisocyanates such as isophorone diisocyanate (IPDI); aromatic-aliphatic diisocyanates such as xylylene diisocyanate (XDI); tolylene diisocyanate (TD)
I), 4,4-diphenylmethane diisocyanate (M
DI) and other aromatic diisocyanates; dimer acid diisocyanate (DDI), hydrogenated TDI (HTD
I) hydrogenated diisocyanates such as hydrogenated XDI (H6XDI) and hydrogenated MDI (H12XDI); dimers, trimers, tetramers and higher polyisocyanates thereof; And polyhydric alcohols such as trimethylolpropane, water or low molecular weight polyester resins.

The blocking agent is not particularly restricted but includes, for example, oxime blocking agents such as methyl ethyl ketoxime, acetoxime, cyclohexanone oxime, acetophenone oxime and benzophenone oxime; phenol blocking agents such as m-cresol and xylenol; Methanol, ethanol, butanol, 2
Alcohol blocking agents such as ethylhexanol, cyclohexanol and ethylene glycol monoethyl ether; lactam blocking agents such as ε-caprolactam; diketone blocking agents such as diethyl malonate and acetoacetate; thiophenol and the like Urea-based blocking agents such as thiourea; imidazole-based blocking agents; carbamic acid-based blocking agents, and the like. Of these, lactam blocking agents, oxime blocking agents, and diketone blocking agents are preferred.

The above-mentioned blocked isocyanate compound is obtained by reacting the above-mentioned isocyanate compound and the above-mentioned blocking agent until free free isocyanate groups disappear by a conventional method. Some of these are commercially available. For example, Desmodur series (manufactured by Sumitomo Bayer Urethane Co., Ltd.), Vernock D series (manufactured by Dainippon Ink and Chemicals, Inc.), Takenate B series (manufactured by Takeda Pharmaceutical Co., Ltd.), Coronate 2500 series (Manufactured by Nippon Polyurethane Industry Co., Ltd.) or the like can be used.

When the above-mentioned blocked isocyanate compound is used as the above-mentioned curing agent (b), the amount of the above-mentioned blocked isocyanate compound provided is equivalent to or more than the equivalent of the hydroxyl value of the above-mentioned film-forming resin (a). The amount may be any amount that can be achieved, and is usually 0.8 to 1.5 times the equivalent. If the amount is too small, the curability decreases, and only a soft coating film can be obtained, and not only the hardness, but also the acid resistance, alkali resistance, and stain resistance decrease.If the amount is too large, the amount corresponding to the added amount is sufficient. In addition to the above-mentioned effects, not only because the block isocyanate compound is added in a large amount, the physical properties such as strength, hardness, and processability of the coating film designed based on the physical properties of the film-forming resin (a) are reduced. And acid resistance and alkali resistance also decrease. Also,
Yellowing and weather resistance of the coating film are apt to decrease. More preferably, it is 1.0 to 1.2 times the equivalent.

When the above blocked isocyanate compound is used as the curing agent (b), a known tin compound such as dibutyltin laurate is usually used as a catalyst for accelerating the reaction with the film-forming resin (a). Is preferred.

The addition amount of the amino resin and the blocked isocyanate compound is determined based on the solid content of the film-forming resin (a).
The amount is 10 to 100 parts by weight, preferably 10 to 50 parts by weight, based on 00 parts by weight. If the addition amount is too small, the curability will be reduced and only a soft coating film will be obtained, and not only the hardness but also the acid resistance, alkali resistance and stain resistance will be reduced. Further, if the addition amount is too large, not only the sufficient effect corresponding to the addition amount can not be obtained, but also the strength, hardness,
Physical properties such as processability are reduced, and acid resistance and alkali resistance are also reduced. Actually, as described above, it is preferable to mix the functional group amount of the curing agent with the functional group amount of the resin in an equivalent relation. When it is desired to change the physical properties of the cured films, they may be combined at slightly different equivalent ratios.

Chromate rust preventive pigment (c) Examples of the chromate rust preventive pigment used in the present invention include strontium chromate, calcium chromate, barium chromate and zinc chromate. The amount of the chromate-based rust preventive pigment to be added is 1 to 150 parts by weight based on 100 parts by weight of the solid content of the curable resin composition containing the film-forming resin (a), the curing agent (b), and the catalyst. . If the amount is less than 1 part by weight, the corrosion resistance decreases. On the other hand, if it exceeds 150 parts by weight, the yellowness of the primer coating film increases,
The yellow color is also reflected in the overcoat, making hue adjustment difficult.
In addition, the chromate-based rust-preventive pigment precipitates and the paint stability tends to decrease, and furthermore, chromium elution due to water cooling (water quenching) after baking the primer increases, resulting in uneven appearance and environmental pollution due to the outflow of chromium. May cause the problem described above. The preferable addition amount of the chromate-based rust preventive pigment is 1 to 100 parts by weight, preferably 5 to 70 parts by weight, more preferably 10 to 50 parts by weight, based on 100 parts by weight of the solid content of the curable resin composition.

Rust preventive pigment containing phosphite powder as a main component
(D) The phosphite powder is not particularly limited, but is preferably a phosphite of one or more metals selected from the group consisting of alkaline earth metals, aluminum, and zinc. It is. In particular, phosphites of alkaline earth metals such as calcium and magnesium are suitable for galvanized steel sheets and aluminum. Also, zinc salts of phosphorous acid are suitable for steel. Phosphite ion and alkaline earth metal ion eluted from the pigment act on the zinc-based metal, and zinc phosphate or a complex salt of calcium or magnesium based on each, or zinc, calcium, magnesium, etc. It is considered that a rustproof film is formed as the basic carbonate. In addition, it is considered that the formation of a zinc phosphate film improves the corrosion resistance of steel.

The average particle size of the phosphite powder is 0.01
It is preferably from 10 to 10 μm. If the average particle size is too small, the surface area increases, the solubility increases, the water-soluble content increases, and problems such as blisters tend to occur. On the other hand, if the average particle size is too large, the sedimentation of the pigment becomes conspicuous, the storage stability of the primer coating is reduced, the appearance of the coating film such as gloss is also reduced, and the appearance quality of the top coat is liable to deteriorate.

The amount of the rust-preventive pigment containing phosphite powder as a main component depends on the film-forming resin (a), the curing agent (b),
And 100 to 100 parts by weight of the solid content of the curable resin composition including the catalyst and 0.5 to 100 parts by weight, preferably 0.5 to 100 parts by weight.
50 parts by weight. If the amount is too small, the combined effect with the chromate-based rust preventive pigment is not exhibited, and if it is too large, no particular effect is exhibited.

Commercially available rust-preventive pigments containing phosphite powder as a main component include E.sub.2 containing calcium phosphite as a main component.
XPERT NP-1000, NP-1020C, EXPERT NP- containing aluminum phosphite as a main component
EXPN NP-1500, NP-153 mainly containing 1100, NP-1102 and zinc phosphite
0, NP-1600 and NP-1700 (all manufactured by Toho Pigment Co., Ltd.), and YM-60 and YM-70 (made by Taihei Chemical Co., Ltd.).

Ion-exchange inorganic powder (e) The ion-exchange inorganic powder used in the present invention is an ion-exchange inorganic powder in which anions or cations are ion-exchanged. Examples of ion-exchanged inorganic powders in which anions have been ion-exchanged include those in which hydrotalcite is ion-exchanged with anions such as chromate ions, nitrite ions, or vanadate ions, and those in which hydrocalumite is used as nitrite ions. And an ion-exchanged anion is carried. Various anticorrosive anions, for example, those obtained by ion exchange of anions such as chromate ion, dichromate ion, phosphate ion, and vanadate ion can be used. In the present invention, since a chromate pigment is used, non-chromate ions such as phosphate ions and vanadate ions are preferred.

When phosphate ions are carried, the ions are exchanged with chloride, which is a corrosive ion, to delay the chloride from reaching the substrate, and at the same time, release phosphate ions. It is considered that corrosion resistance is obtained by forming a protective film such as zinc phosphate on the surface. Further, it is considered that the ion exchange with the hydroxyl ions generated by the metal corrosion prevents the increase of the pH at the metal interface, thereby preventing the adhesion of the coating film from deteriorating. In addition, it is considered that the vanadate ion repairs after the chromate film, which is an oxidizing ion, is broken.

Examples of the ion-exchanged inorganic powder obtained by ion-exchange of anions include IXE-500, IXE-550, and IXE-550.
XE-700, IXE-800, IXE-1000 (all manufactured by Toa Gosei Chemical Industry Co., Ltd.) and the like.

Examples of the ion-exchanged inorganic powder having ion-exchanged and supported cations include Sealdex series (manufactured by Grace) which is a silica-based ion-exchanger having ion-exchanged and carried calcium ions. Dex CP4-7394 can be particularly preferably used. Other ion-exchange inorganic powders obtained by ion-exchanging cations include IX-100, IXE
-200, IXE-300, and IXE-400 (all manufactured by Toa Gosei Chemical Industry Co., Ltd.). Various cations can be ion-exchanged and carried on these. Calcium ions exchange with highly soluble ions such as sodium ions and H ⁺ (protons), and the released Ca ions form a protective film such as basic zinc calcium carbonate on the zinc-based alloy plating surface. It seems to be effective.

The amount of the ion-exchanger inorganic powder is from 0.1 to 100 parts by weight of the solid content of the curable resin composition.
50 parts by weight. The content of the ion-exchange inorganic powder is 0.
If it is less than 1 part by weight, the corrosion resistance is reduced. On the other hand, when the amount exceeds 50 parts by weight, blisters are easily generated. The preferable content of the inorganic substance particles is 2 to 20 parts by weight.

The ion-exchange inorganic powder (e) in the present invention may be coated on the surface of the phosphite powder (d). Therefore, in the present invention, the surface of the phosphite powder (d) is coated with the ion-exchange inorganic powder (e) as at least a part of the phosphite powder (d) and the ion-exchange inorganic powder (e). A composite powder may be used.

Inorganic substance particles (f) and organic polymer particles
(F) The inorganic substance particles used in the second aspect of the present invention include natural or synthetic mica, gypsum, barium sulfate, diatomaceous earth, aluminum powder, aluminum flake, calcium silicate, iron oxide, kaolin clay, talc, carbonate Calcium, glass, feldspar, quartz, silica fine powder and manganese dioxide. Examples of the glass include glass powder and glass fiber. Examples of the fine silica powder include wet silica, dry silica, and colloidal silica. The Mohs hardness of the inorganic substance particles is preferably from 5 to 8, more preferably from 6 to 7. In the case where the inorganic material particles are other than the above-mentioned glass fiber and silica fine powder, it is preferable to use those having a particle size of 3 to 30 μm, and in the case of silica fine powder, those having a particle size of 5 μm or less. It is preferably used. In the case of glass fiber, the diameter is 1 to 30 μm,
It is a glass fiber having a fiber length of 1 to 200 μm and preferably a Mohs hardness of 5 to 8.

The amount of the inorganic particles is 1 to 30 parts by weight based on 100 parts by weight of the solid content of the curable resin composition. When the content of the inorganic substance particles is less than 1 part by weight, the scratch resistance is reduced. On the other hand, when the amount exceeds 30 parts by weight, the coating film strength cannot be obtained and the processability is poor.
In addition, the surface smoothness of the formed coating film may decrease. The preferred content of the inorganic substance particles is 5 to 25 parts by weight. When the inorganic substance particles include silica fine powder, the mixing ratio of the inorganic substance particles other than the silica fine powder to the silica fine powder (inorganic substance particles other than the silica fine powder / silica fine powder)
Is preferably from 98/2 to 70/30.

In the second aspect of the present invention, the above-mentioned inorganic substance particles and / or organic polymer particles are added. Examples of the organic polymer particles that can be used include fluororesins including polytetrafluoroethylene, polyethylene, polypropylene, silicone, cellulose, urethane, nylon, polyester, phenolic resins, acrylic resins, amino resins, polyamide resins and modifications thereof. Resins. As such organic polymer particles,
It is preferable to use one having a particle size of 0.001 to 30 μm.

Preferred organic polymer particles have a particle size of 0.1 to
10 μm polytetrafluoroethylene, polyamide resin, polyethylene. The amount of the organic polymer particles is 0.5 to 10 parts by weight based on 100 parts by weight of the solid content of the curable resin composition. When the amount of the organic polymer particles is less than 0.5 part by weight, the scratch resistance is reduced.
On the other hand, when the amount exceeds 10 parts by weight, the strength of the coating film cannot be obtained and the workability becomes poor. The preferred amount of the organic polymer particles is 0.5 to 5 parts by weight.

In the primer composition according to the second aspect of the present invention, scratch resistance is improved by adding inorganic substance particles and / or organic polymer particles. The reason why the scratch resistance is improved by adding the above-mentioned inorganic substance particles and / or organic polymer particles is considered to be due to the following effects.

That is, the presence of the above-mentioned filler (inorganic substance particles and / or organic polymer particles) in the coating film ensures that even if a stress is applied to the coated steel sheet, the point of action of the stress is different from that of the coating film. It migrates to the surface of the filler in the coating film without forming an interface with the substrate (steel plate substrate). When the stress applied to the coating film is relieved by the filler as described above, scratches are less likely to be formed in the coating film.

Further, even if a shearing force is applied to the coating film, internal sliding due to the filler (particularly, organic polymer particles) is effective and the force is dispersed, so that the coating film is less likely to be broken. As described above, the use of inorganic polymer particles and organic polymer particles such as polytetrafluoroethylene, polyimide, and polyamide powder, which have a lubricating effect due to internal slip, impairs general coating film performance such as coating film gloss and workability. And the scratch resistance is improved.

Further, by adding such a filler, the surface of the coating film (primer coating film) becomes moderately rough, whereby the interlayer adhesion with the top coating film is improved,
It also has the advantage of preventing peeling of the coating film.

Other Additives The primer composition of the present invention may further contain, if necessary, a color pigment, an extender pigment and other rust-preventive pigments. Such pigments include, for example, titanium dioxide, phthalocyanine blue, phthalocyanine green,
Examples include coloring pigments such as quinacdrine, indanthrone, isoindolinone, perylene, anthrapyrimidine, carbon black, benzimidazolone, graphite, yellow iron oxide and red iron oxide, and extenders such as clay.

Further, various additives such as a benzophenol-based ultraviolet absorber, a surface conditioner such as silicone or an organic polymer, an anti-sagging agent and a thickener can be added. These additives can be blended in an amount of 5 parts by weight or less based on 100 parts by weight of the solid content of the curable resin composition to improve paint performance and coating film performance. However, if the amount of these additives is too large, repelling may occur at the time of forming a coating film, or interlayer adhesion may be deteriorated. A solvent may be appropriately added for viscosity adjustment (workability).

The components are mixed by using a paint shaker, dissolver, ball mill,
A device such as a sand grind mill or a kneader is used. The method for forming a coating film of the present invention comprises the steps of: coating the primer composition for a precoated metal of the present invention with a galvanized steel sheet, a zinc / aluminum alloy plated steel sheet, an aluminum / zinc alloy plated steel sheet, a zinc / iron alloy plated steel sheet, an aluminum plated steel sheet; A coating film forming method characterized in that at least one surface of an aluminum plate or a stainless steel plate is coated so as to have a dry film thickness of 1 to 10 μm.

The coating in the coating film forming method of the present invention can be performed, for example, as follows. First, a steel sheet to be coated is degreased and then subjected to a chemical conversion treatment. Degreasing (surface cleaning) and chemical conversion treatment may be performed by a known method, and a method suitable for a steel sheet to be used is appropriately selected.

Next, the above-mentioned primer composition of the present invention is applied. At the time of coating, the coating composition is adjusted in advance to an appropriate viscosity as described above. The coating method is not particularly limited, and ordinary coating methods such as air spray coating, airless coating, and electrostatic coating can be used. In particular, when the accuracy of the coating thickness, the smoothness of the coating surface, and the like are required, a gravure coating method, a roll coating method, a curtain coating method, a bar coating method, and an offset gravure coating method are preferably used.
In the case of the precoat method, it is preferable to adopt a roll coating method.

In the method for forming a coating film of the present invention, the above-mentioned primer composition is applied to an object to be coated. The coating may be performed on one side of the object to be coated (steel plate) or on both sides. There may be. If the primer composition of the present invention is applied to both sides of the steel sheet, the corrosion resistance is further improved, but it may be applied only to one side of the steel sheet in consideration of required performance, production cost and the like. When the primer composition of the present invention is undercoated on only one side, a conventional undercoat may be used as the undercoat on the other side. In addition, the primer composition of the present invention can be applied to the coating on the surface to be the back surface when a steel plate is processed into a product. By applying the primer composition of the present invention on the back surface, the corrosion current is suppressed even on the edge end surface where the coating film is not formed,
Edge creep properties of both surfaces can be further improved.

The thickness of the coating film obtained by this primer coating is 1 to 10 μm, preferably 2 to 10 μm, and more preferably 3 to 8 μm as a thickness when dried. When the film thickness is less than 1 μm, the corrosion resistance is reduced. When the thickness exceeds 10 μm, the smoothness of the coating film surface may be reduced. In addition,
On the surface which becomes the back surface when the steel plate is processed into a product, this film thickness is 5 to 25 μm, preferably 8 to 20 μm.
And

After the above-mentioned primer coating was performed,
Bake at 30 ° C. for 20 to 60 seconds. As described above, after forming the primer coating, oil-free polyester, vinyl chloride, silicone polyester, fluororesin, thermosetting acrylic resin, melamine alkyd resin,
A well-known top coat made of a silicone acrylic resin or the like can be applied. The coating at this time may be performed by a known method. The combination of the undercoat paint (primer paint) and the resin for the overcoat paint described above may be a combination of paints containing the same kind of resin as a main component as long as there is no problem in adhesion between the overcoat paint film and the undercoat paint film. A combination of paints containing different kinds of resins as main components may be used.

The thickness of the top coat is preferably 10 to 20 μm in the case of a material other than vinyl chloride, and 100 to 200 μm in the case of a top coat mainly composed of vinyl chloride.

After the top coat is applied, baking is performed at 190 to 250 ° C. for 20 to 60 seconds. In addition, an intermediate coating may be performed between the above-mentioned undercoating and topcoating, and a paint (topcoating paint or undercoating paint) suitable for the undercoating paint and the topcoating paint as appropriate according to the required performance of the coating film. Apply the same type of paint). At this time, baking is preferably performed after the intermediate coating, so that a so-called three-coat three-bake process is preferably performed.

The coated article of the present invention is obtained by applying the above primer composition of the present invention or applying the above-mentioned coating film forming method of the present invention and then applying the above-mentioned top coat. Things.

[0061]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Production Example 1: Hydrotalcite /
Manufacture of vanadate ion exchanger inorganic powder Hydrotalcite (Kyowa Chemical Industry Co., Ltd., trade name "DH
T-4 ") was heated at 500 ° C. for 1 hour and cooled in a desiccator to room temperature. Next, 1 liter of an aqueous solution of Na ₃ VO ₄ (9.4 g / l) was placed in a 2 liter glass beaker, and heat-treated hydrotalcite 15 was placed therein.
g was added and stirred at 50 ° C. for 1 hour. At that time, p
The pH of the mixture was maintained at 6.5 while monitoring H with a pH meter.

Next, the reaction product was settled using a centrifuge to remove the supernatant, and then washed with deionized water. The washing operation was repeated 5 times, and the conductivity of the supernatant was 45 μs /
cm, the precipitate was taken out and dried at 105 ° C. for 3 hours to obtain a white pigment.

Production Example 2: Hydrotalcite / nitrite
Production of On-Exchanger Inorganic Powder In place of the aqueous solution of Na ₃ VO _{4, an} aqueous solution of NaNO ₂ (6.
9 g / liter), and an inorganic powder composed of hydrotalcite ion-exchanged with nitrite ions was produced under the same conditions as in Production Example 1 except that the pH of the mixture was adjusted to 9.5.

Production Example 3: Surface of phosphite powder was
Rotarsite / nitrite ion exchanger coated with inorganic powder
Production of Composite Particles 100 parts by weight of calcium / zinc phosphite powder (trade name “EXPERPNP-1020C” manufactured by Toho Pigment Industry Co., Ltd.) and the hydrotalcite / nitrite ion exchanger inorganic powder 5 produced in Production Example 2 above The mixture was stirred in a Henschel mixer (rotation speed: 2200 rpm) for 10 minutes, and the mixture was stirred for 10 minutes. The stirring was stopped once, the powder mixture adhering to the lid of the container and the vessel wall was scraped off, and the mixture was again stirred and mixed for 30 minutes. As described above, composite particles obtained by coating the surface of the calcium / zinc phosphite powder with the hydrotalcite / nitrite ion exchanger inorganic powder were obtained.

Examples 1 to 7 and Comparative Examples 1 to 3 Primer coatings were prepared in the proportions shown in Tables 1, 2 and 3. The blending amount indicates a solid content. 40 parts by weight of the film-forming resin (a), each component other than the curing agent (b) and the curing catalyst were mixed, and mixed with a glass bead mill.
Time dispersed. After filtering the beads, the particle size is measured with a particle gauge, and after confirming that the particle size is 10 μm or less, the remaining film-forming resin (a), the curing agent (b), and the curing catalyst are added, and the mixture is uniformly dispersed with a disper. To obtain a primer coating.

The PWC of the obtained paint is shown in each table. The obtained primer paint was applied to a steel plate (thickness: 0.6 mm) of a material shown in each table using a bar coater so as to have a dry film thickness shown in each table, baked and dried. The reached plate temperature was 210 ° C. In addition, the steel plate of each material used what apply | coated the coating type chromate processing liquid (the product name "Surfcoat NRC300" by Nippon Paint Co., Ltd.) beforehand, and dried at 80 degreeC. The amount of chromium adhered was 20 mg /
m ² .

Next, the top coat shown in each table was applied so that the dry film thickness became 20 μm. The reached plate temperature was 22
It was 0 ° C. Hereinafter, the components used in each table will be described.

(A) Film-forming resin Polyester resin “Vylon 300”: a polyester resin manufactured by Toyobo, Tg 7 ° C., number average molecular weight 26000,
Hydroxyl value 4, acid value 2 or less Epoxy resin "Epototo YD7020": phenol-modified bisphenol type epoxy resin manufactured by Toto Kasei Co., Ltd.

(B) Curing agent Melamine resin "Cymel 235": methoxy / butoxy mixed modified melamine resin manufactured by Mitsui Cytec Co., Ltd. Melamine resin "Sumimar M40S": methylated melamine resin manufactured by Sumitomo Chemical Co., Ltd. Melamine resin Cymel 303 ": Methylated melamine resin manufactured by Mitsui Cytec Co., Ltd.-Blocked isocyanate" CORONATE 2536 ": Nippon Polyurethane Industry Co., Ltd., lactam block / methylene diisocyanate (MDI) system

Curing catalyst p-toluenesulfonic acid DMEA salt: diethanolamine salt of p-toluenesulfonic acid

(C) Chromate-based rust preventive pigment Strontium chromate: Strontium chromate N (d) phosphite-based rust preventive pigment manufactured by Kikuchi Color Co., Ltd. "EXPERT NP1020C": manufactured by Toho Pigment Industry Co., Ltd .; "EXPERT NP1020C N-1": manufactured by Toho Pigment Industry Co., Ltd., particle size 0.5 to 1.0 m

(E) Inorganic powder of ion exchanger "Sealdex CP4-7394": silica-based Ca ion exchanger manufactured by Grace

(F) Inorganic substance particles and organic polymer particles Glass fiber “Microsurface strand REV-
1 ": Glass fiber manufactured by Nippon Glass Fiber Co., Ltd.-Barium sulfate:" Precipitable barium sulfate 100 "manufactured by Sakai Chemical Industry Co., Ltd.-Feldspar powder:" MINEX 7 "manufactured by Shiraishi Calcium Co.

• Wet silica "Nipsil E200": manufactured by Nippon Silica Co., Ltd., average particle size: about 3 μm. • Wet silica "Nipsil SS70B": manufactured by Nippon Silica Industry Co., average particle size: 2 μm. • Wet silica "Nipsil SS170X": Nippon Silica. Made by Kogyo Co., Ltd., average particle size 3 μm ・ Nylon fine powder: "Orgasol 2" manufactured by Rilsan Japan
002EXG ", nylon 11 particles

Other pigments-Titanium oxide "CR95": "Taipec CR95" manufactured by Ishihara Sangyo Co., Ltd.-Titanium oxide "CR97": "Taipec CR97" manufactured by Ishihara Sangyo Co., Ltd.-Titanium oxide "R930": "Taipec R930" manufactured by Ishihara Sangyo Co., Ltd. "EXPERT NP530": manufactured by Toho Pigment Industry Co., Ltd.
Zinc phosphate pigment

Material: Hot-dip Al / Zn plated steel sheet: 55% Al / 45% Zn
Galvanized steel sheet

Topcoat paint ・ Polyester resin “Flexcoat”: Nippon Paint Co., Ltd. polyester resin topcoat “Flexcoat1”
500HQ ”・ Polyester resin“ Nippe Supercoat ”: Nippon Paint Co., Ltd. polyester resin topcoat“ Nippe Supercoat 300HQ ”

[0078]

[Table 1]

[0079]

[Table 2]

[0080]

[Table 3]

With respect to the sample coated plate (test plate) coated with the primer paint and the top coat obtained as described above, the edge creep resistance, the white rust resistance in the processed portion, and the scratch resistance were determined as follows. evaluated.

The edge creep resistance test plate was cut into a size of 7 cm × 20 cm, and the cut three sides were sealed with a polyester tape. In addition,
The seal width was 5 mm from the cut end. afterwards,
Each test plate was subjected to a salt spray test. As the salt spray test, a test was performed for 750 hours in accordance with JIS Z2371. With respect to the test plate after the test, the maximum length (mm) from the unsealed piece of the blister formed on the coating film was measured.

Processed part White rust property Each test plate was cut into a size of 7 cm × 18 cm,
In the side having a length of 1 cm, bending is performed at a portion 15 cm from the end and 2T processing (1 mm from the end so as to form a J-shape as viewed from the side so as to form a gap capable of sandwiching two plates.
Bend this plate at the part of 5cm) and JIS Z2
A salt spray test was performed according to 371. After the completion of the test for 1000 hours, the occurrence of white rust from the place where the bending was performed was evaluated according to the following criteria. 3: White rust generation less than 20% 2: White rust generation less than 40% 20% or more 2: White rust generation 40% or more

Scratch Resistance The test coating film was scratched (with a force of 0.5 kg) with a 10-yen coin having no jagged outer peripheral surface, and the damage of the test coating film was evaluated according to the following criteria. 3: Even if the surface has scratches and peeling, the degree is small and a part of the overcoat film remains, and the undercoat (primer) coating film does not appear. 2: A part of the undercoat (primer) coating is shaved,
Undercoat (primer) coating with peeling. 1: Both the top coat and the undercoat (primer) coat are scraped off, exposing the substrate (chemical conversion treated surface of the substrate). Table 4 shows the evaluation results.

[0085]

[Table 4]

As is evident from the results in Table 4, the precoated metals of Examples 1 to 7 according to the present invention are superior to Comparative Examples 1 to 3 in edge creep resistance and white rust in the processed part. It turns out that it shows good corrosion protection.

Further, in Examples 3 to 5 in which inorganic substance particles and / or organic polymer particles were blended according to the second aspect of the present invention.
It can be seen that the coating No. 7 has excellent scratch resistance.

[0088]

According to the present invention, in the pre-coated metal, the corrosion resistance of the end face, the cut portion and the processed portion can be enhanced.

According to the second aspect of the present invention, a precoated metal having excellent scratch resistance can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 7/12 C09D 7/12 AZ 161/20 161/20 175/04 175/04 // C08G 18/80 C08G 18/80 (72) Inventor Yoichi Tozaki 19-17 Ikedanakamachi, Neyagawa-shi, Osaka Nippon Paint Co., Ltd.

Claims (13)

[Claims] 1. A film forming resin comprising: (a) a curing agent comprising an amino resin and / or a blocked isocyanate compound in an amount of 10 to 100 parts by weight based on 100 parts by weight of a solid content of the film forming resin; (C) at least one chromate-based rust-preventive pigment based on 100 parts by weight of the solid content of the curable resin composition containing
0 parts by weight, and (d) a rust-preventive pigment containing phosphite powder as a main component 0.5 to 0.5 parts by weight.
A primer composition for a precoated metal, comprising 100 parts by weight and (e) 0.1 to 50 parts by weight of an ion-exchange inorganic powder obtained by ion exchange of an anion or a cation. 2. The solid content of (a) the film-forming resin is 10
(C) at least one chromate-based rust-preventive pigment based on 0 parts by weight
0 parts by weight, and (d) a rust-preventive pigment containing phosphite powder as a main component 0.5 to 0.5 parts by weight.
A primer composition for a precoated metal, comprising 100 parts by weight and (e) 0.1 to 50 parts by weight of an ion-exchange inorganic powder obtained by ion exchange of an anion or a cation. 3. A film-forming resin comprising: (a) a curing agent comprising an amino resin and / or a blocked isocyanate compound in an amount of 10 to 100 parts by weight based on 100 parts by weight of a solid content of the film-forming resin. (C) at least one chromate-based rust-preventive pigment based on 100 parts by weight of the solid content of the curable resin composition containing
0 parts by weight, and (d) a rust-preventive pigment containing phosphite powder as a main component 0.5 to 0.5 parts by weight.
100 parts by weight; (e) 0.1 to 50 parts by weight of an ion-exchanged inorganic powder obtained by ion exchange of anions or cations; (f) 1 to 30 parts by weight of inorganic substance particles and / or organic polymer particles. 5 to 10 parts by weight of a primer composition for a precoated metal. 4. The solid content of (a) the film-forming resin is 10.
(C) at least one chromate-based rust-preventive pigment based on 0 parts by weight
0 parts by weight, and (d) a rust-preventive pigment containing phosphite powder as a main component 0.5 to 0.5 parts by weight.
100 parts by weight; (e) 0.1 to 50 parts by weight of an ion-exchanged inorganic powder obtained by ion exchange of anions or cations; (f) 1 to 30 parts by weight of inorganic substance particles and / or organic polymer particles. 5 to 10 parts by weight of a primer composition for a precoated metal. 5. The phosphite powder (d) is a phosphite of one or more metals selected from the group consisting of alkaline earth metals, aluminum and zinc. 5. The primer composition for a precoated metal according to any one of 4. 6. The method according to claim 1, wherein the average particle diameter of the phosphite powder (d) is 0.01 to 10 μm.
14. The primer composition for a precoated metal according to the above item. 7. The ion-exchanged inorganic powder (e) is an ion-exchanged inorganic powder ion-exchanged with an alkaline earth metal ion as a cation or a vanadate ion or a nitrite ion as an anion. 1 to
7. The primer composition for a precoated metal according to any one of 6. 8. The surface of the phosphite powder (d) as at least a part of the phosphite powder (d) and the ion-exchange inorganic powder (e). The primer composition for a precoated metal according to any one of claims 1 to 7, wherein the composite powder coated with (1) is used. 9. The method according to claim 9, wherein the inorganic substance particles are natural or synthetic mica, gypsum, barium sulfate, calcium silicate, iron oxide,
Kaolin clay, talc, calcium carbonate, diatomaceous earth,
The primer composition for a precoated metal according to any one of claims 3 to 8, wherein the primer composition is one or more particles selected from aluminum powder, aluminum flake, glass, feldspar, quartz, silica fine powder, and manganese dioxide. Stuff. 10. The inorganic substance particles include silica fine powder, and (inorganic substance particles other than silica fine powder) /
The primer composition for a precoated metal according to any one of claims 3 to 9, wherein the weight ratio of the (silica fine powder) is 98/2 to 70/30. 11. The method according to claim 11, wherein the organic polymer particles are a fluororesin,
The primer composition for a pre-coated metal according to any one of claims 3 to 10, which is a polyolefin, silicone, cellulose, polyurethane, polyamide, polyester, phenol resin, acrylic resin, amino resin, or a modified resin thereof. 12. The precoated metal primer composition according to claim 1, wherein the precoated metal primer composition is a galvanized steel sheet, a zinc / aluminum alloy plated steel sheet, an aluminum / zinc alloy plated steel sheet, or a zinc / iron alloy plated steel sheet. , An aluminum-plated steel plate, an aluminum plate, or a stainless steel plate having a dry film thickness of 1 to 10 μm
m. 13. A coated article characterized by applying the primer composition according to any one of claims 1 to 11 or applying the method according to claim 12 and then applying a top coat. .