JPH10219188A - Coating composition and metallic plate coated therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating material which can form a coating film having a good hardness and processability and excellent design properties, resistance to contact mark and scratch resistance. SOLUTION: This invention provides a coating composition comprising 100 pts.wt. film-forming resin component comprising 65-95 pts.wt. hydroxyl polyester resin having a number - average molecular weight of 2,000-35,000, a glass transition temperature (Tg) of -25 to 35 deg.C and a hydroxyl value of 3-100mgKOH/g and 5-35 pts.wt. at least one crosslinking agent selected among amino resins and blocked polyisocyanate compounds and 1-20 pts.wt. at least resin powder selected among polyamide resin powders and polypropylene resin powders and having a means particle diameter of 20-60μm and a coated metallic sheet prepared by coating a metallic sheet with a polyester primer having a Tg of 40-100 deg.C and coating the primer film with a cured film of the above composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition having good hardness and workability and capable of forming a coating film having excellent designability, contact trace resistance and scratch resistance, and particularly to a precoated steel sheet for processing objects. The present invention relates to a coating composition suitable for use and a coated metal plate obtained by applying the coating composition.

[0002]

2. Description of the Related Art
Pre-painted coating for container processing
Paints in which a curing catalyst is blended with a mixture of a polyester resin as a base resin and a methyl etherified methylol melamine resin as a cross-linking agent are widely used because of their excellent balance between hardness and workability. In recent years, in addition to hardness and workability, performances such as designability, contact trace resistance, and scratch resistance have been required for precoated steel sheets for vessel processing.

In the above-mentioned conventional polyester resin-methyl etherified methylol melamine resin-based coating composition,
By increasing the amount of methyl etherified methylol melamine resin and increasing the amount of curing catalyst, paints with a good balance between the hardness of the coating and the workability have been proposed. The abrasion resistance has not yet been solved.

[0004] The above-mentioned contact trace resistance may be caused by attaching a rubber or plastic suction cup to an outer plate of, for example, a refrigerator or a microwave oven and hanging a memo or a pot holder. If left, or if the painted electrical product is wrapped and stacked with plastic film or styrofoam, it is resistant to the deterioration of the painted surface due to the trace of contact of the plastic film or styrofoam on the coating film . Contact trace resistance is
Generally, when the glass transition temperature (Tg point) of the coating film is high, for example, about 80 ° C. or higher, the film is good. However, when the Tg point is high, there is a problem that the workability is greatly reduced.

[0005] The abrasion resistance is resistance to a coating film being damaged when a painted article is packed in a corrugated cardboard, comes into contact with a hard object during transportation, or is scratched by a human nail. The abrasion resistance can be improved to some extent by increasing the coating film hardness, the sliding property of the coating film, and the crosslinking density of the coating film. However, there is a problem that the abrasion resistance cannot be improved to a satisfactory level even if the slip property of the coating film is improved.

[0006] Further, as a method of imparting design properties to a coating film, it has been practiced to blend a resin fine powder into the coating material to form a coating film having an uneven feeling.
There has been a problem that the processability of the coating film generally obtained is reduced.

As described above, paints having good hardness and workability and capable of forming a coating film having excellent design properties, stain resistance, contact mark resistance and scratch resistance have not been developed. The appearance of a paint that satisfies the performance of the above has been awaited.

[0008] The present invention has good hardness and workability,
An object of the present invention is to obtain a paint capable of forming a coating film having excellent design properties, stain resistance, contact trace resistance, and scratch resistance.

[0009]

Means for Solving the Problems The present inventors have found that the above object can be achieved by blending a specific polyamide resin powder in a specific polyester resin-based coating, and completed the present invention. I came to.

That is, the present invention provides (A) a number average molecular weight of 2,000 to 35,000, a glass transition temperature of -25 ° C.
Film formation comprising 35 to 95 parts by weight of a hydroxyl group-containing polyester resin having a hydroxyl value of 3 to 100 mgKOH / g at 35 ° C. and 5 to 35 parts by weight of at least one crosslinking agent selected from (B) an amino resin and a blocked polyisocyanate compound. For a total amount of 100 parts by weight of the conductive resin component,
(C) 1 to 20 parts by weight of at least one resin powder selected from polyamide resin powder and polypropylene resin powder and having an average particle diameter of 20 to 60 μm, and (D) a curing catalyst of 0.1 to It is intended to provide a coating composition characterized by containing 2.0 parts by weight.

The present invention further provides a top coating cured coating composition according to claim 1 on a metal plate via a polyester resin-based or modified polyester resin-based primer coating having a glass transition temperature of 40 to 100 ° C. An object of the present invention is to provide a coated metal plate having a film formed thereon.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the coating composition of the present invention will be described in more detail.

Polyester Resin (A) The polyester resin as the component (A) in the composition of the present invention is a polyester resin containing a hydroxyl group, and is an oil-free polyester resin, an oil-modified alkyd resin, or a modified product of these resins. Examples thereof include urethane-modified polyester resins, urethane-modified alkyd resins, and epoxy-modified polyester resins.

The oil-free polyester resin comprises an esterified product of a polybasic acid component and a polyhydric alcohol component. Examples of the polybasic acid component include one or more selected from phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic acid, fumaric acid, adipic acid, sebacic acid, maleic anhydride, and the like. Dibasic acids and lower alkyl esterified products of these acids are mainly used, and if necessary, monobasic acids such as benzoic acid, crotonic acid, pt-butylbenzoic acid, trimellitic anhydride, methylcyclohexenetricarboxylic acid And tribasic or higher polybasic acids such as pyromellitic anhydride. Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol,
Dihydric alcohols such as neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol and 1,6-hexanediol are mainly used, and if necessary, glycerin, trimethylolethane, trimethylolpropane, pentane A trihydric or higher polyhydric alcohol such as erythritol can be used in combination. These polyhydric alcohols can be used alone or in combination of two or more. The esterification or transesterification of both components can be carried out by a method known per se. As the acid component, isophthalic acid, terephthalic acid,
And lower alkyl esters of these acids are particularly preferred.

The alkyd resin is obtained by reacting an oil fatty acid by a method known per se in addition to the acid component and the alcohol component of the above-mentioned oil-free polyester resin. Soybean oil fatty acids, linseed oil fatty acids, safflower oil fatty acids, tall oil fatty acids, dehydrated castor oil fatty acids, kiri oil fatty acids and the like can be mentioned. The oil length of the alkyd resin is preferably 30% or less, particularly preferably about 5 to 20%.

As the urethane-modified polyester resin,
The oil-free polyester resin, or a low-molecular-weight oil-free polyester resin obtained by reacting an acid component and an alcohol component used in the production of the oil-free polyester resin, reacts with a polyisocyanate compound by a method known per se. Examples include: Further, the urethane-modified alkyd resin, the alkyd resin, or a low molecular weight alkyd resin obtained by reacting each component used in the production of the alkyd resin was reacted with a polyisocyanate compound by a method known per se. Things are included. Examples of polyisocyanate compounds that can be used when producing urethane-modified polyester resin and urethane-modified alkyd resin include hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate,
4,4'-methylenebis (cyclohexyl isocyanate), 2,4,6-triisocyanatotoluene, and the like. In general, as the urethane-modified resin, those having a modification degree in which the amount of the polyisocyanate compound forming the urethane-modified resin is 30% by weight or less based on the urethane-modified resin can be suitably used.

As the epoxy-modified polyester resin,
Using a polyester resin produced from each component used in the production of the above polyester resin, a reaction product of a carboxyl group of this resin and an epoxy group-containing resin, and a hydroxyl group in the polyester resin and a hydroxyl group in the epoxy resin are polyisocyanate. Reaction products such as addition, condensation, and grafting of a polyester resin and an epoxy resin, such as a product bonded via a compound, can be given.
In general, the degree of modification in such an epoxy-modified polyester resin is preferably such that the amount of the epoxy resin is 0.1 to 30% by weight based on the epoxy-modified polyester resin.

Among the polyester resins described above, an oil-free polyester resin is particularly preferable.

The polyester resin (A) has a number average molecular weight of 2,000 to 35,000, preferably 5,000 to 3
000, glass transition temperature (Tg point) -25 to 35
° C, preferably -10 ° C to 30 ° C, hydroxyl value 3 to 100
mgKOH / g, preferably 5 to 50 mgKOH / g.

In the present invention, the glass transition temperature (Tg)
Is measured by differential thermal analysis (DTA), and the number average molecular weight is measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve.

When the number average molecular weight of the polyester resin (A) is less than 2,000, the processability is poor.
If it exceeds 5,000, the degree of cross-linking of the coating film obtained will be low, and the stain resistance, contact trace resistance and scratch resistance will be reduced. When the Tg point is lower than -25 ° C, the hardness of the obtained coating film is low, and the stain resistance is lowered. On the other hand, when the Tg point is higher than 35 ° C, the workability of the obtained coating film is deteriorated. The hydroxyl value is 3 mgKOH / g
If it is less than 100, the degree of crosslinking of the obtained coating film is low, and the stain resistance, the contact mark resistance, and the scratch resistance are reduced.
If it exceeds gKOH / g, the workability of the obtained coating film will deteriorate.

Crosslinking Agent (B) The crosslinking agent as the component (B) is capable of reacting with the polyester resin (A) to cure the resin (A). Representative examples thereof include amino resins and block resins. Polyisocyanate compound.

Examples of the amino resin include a methylolated amino resin obtained by reacting an aldehyde with an amino component such as melamine, urea, benzoguanamine, acetoguanamine, steloguanamine, spiroguanamine and dicyandiamide. Examples of the aldehyde used in the above reaction include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like. Further, those obtained by etherifying the above methylolated amino resin with a suitable alcohol can also be used as the amino resin. Examples of the alcohol used for the etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like.

Of the above amino resins, melamine resins are preferred, and methyl etherified melamine resins, mixed etherified melamine resins of methyl ether and butyl ether, or methyl etherified melamine resins or the above mixed etherified melamine resins are preferred. It is preferable that the mixed melamine resin contains 60% by weight or more and 40% by weight or less of the butyl etherified melamine resin.

Specific examples of the melamine resin include Cymel 300, 303, 325, 327, 350, 730, 736, and 738 (all of which are manufactured by Mitsui Cytec Co., Ltd.), and melan. 522, 523
[These are all manufactured by Hitachi Chemical Co., Ltd.], Nicaraq MS
001, MX430, and MX650 (all manufactured by Sanwa Chemical Co., Ltd.), Sumimar M-55, and M-M
100 and M-40S [all of which are Sumitomo Chemical Co., Ltd.]
Methyl etherified melamine resins such as Resin 740 and 747 (all manufactured by Monsanto); Uban 20SE and 225 (all manufactured by Mitsui Toatsu Co., Ltd.), Super Beckamine J820-60 , L
-117-60, L-109-65, 47-508
Butyl etherified melamine resins such as -60, L-118-60, and G821-60 (all of which are manufactured by Dainippon Ink and Chemicals, Inc.); Cymel 232, 26
6, XV-514 and 1130 (all of which are manufactured by Mitsui Cytec Co., Ltd.), Nikarac MX500, and MX
600, MS35, MS95 [all, all manufactured by Sanwa Chemical Co., Ltd.], Regimin 753, 755 [all, manufactured by Monsanto Co., Ltd.], Sumimar M-66B
Mixed etherified melamine resin of methyl ether and butyl ether such as [manufactured by Sumitomo Chemical Co., Ltd.]. These melamine resins can be used alone or as a mixture of two or more.

The blocked polyisocyanate compound is a compound obtained by blocking free isocyanate groups of the polyisocyanate compound with a blocking agent.

Examples of the polyisocyanate compound before blocking include aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate; cycloaliphatic diisocyanates such as hydrogenated xylylene diisocyanate or isophorone diisocyanate; tolylene diisocyanate Or an organic diisocyanate itself such as an aromatic diisocyanate such as 4,4'-diphenylmethane diisocyanate, or an adduct of each of these organic diisocyanates with a polyhydric alcohol, a low molecular weight polyester resin or water, or each organic diisocyanate as described above. Cyclic polymers among diisocyanates, and isocyanate / biuret compounds are also included.

Examples of the blocking agent for blocking the isocyanate group include phenols such as phenol, cresol and xylenol; ε-caprolactam;
Lactams such as valerolactam, γ-butyrolactam, β-propiolactam; methanol, ethanol, n-
Or i-propyl alcohol, n-, i- or t-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether,
Alcohols such as benzyl alcohol; oximes such as formamidoxime, acetoaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime; dimethyl malonate, diethyl malonate, ethyl acetoacetate, ethyl acetoacetate, methyl acetoacetate, acetylacetone A blocking agent such as an active methylene type can be suitably used.

The free isocyanate groups of the polyisocyanate compound can be easily blocked by mixing the polyisocyanate compound with the blocking agent.

The crosslinking agent (B) may be composed of one kind of crosslinking agent or a mixture of two or more kinds of crosslinking agents.

In the composition of the present invention, the blending amount of the polyester resin (A) and the crosslinking agent (B) in 100 parts by weight of the resin component must be within the following range.

Polyester resin (A): 65 to 95 parts by weight, preferably 70 to 90 parts by weight, Crosslinking agent (B): 5 to 35 parts by weight, preferably 10 to 30 parts by weight.

Resin powder (C) The resin powder (C) is selected from polyamide resin powder and polypropylene resin powder, and has an average particle size of 20 to 60 μm.
m is at least one resin powder. The resin powder (C) is to improve the design by imparting irregularities to the coating film, and to improve the contact trace resistance and the scratch resistance.

In the composition of the present invention, the resin powder (C)
Is selected from polyamide resin powders and polypropylene resin powders.Other types of resin powders and inorganic powders cannot satisfy all of the design properties, contact trace resistance, and scratch resistance. Only the powder and / or the polypropylene resin powder could satisfy the above performance. As the resin powder (C), a polyamide resin powder is particularly preferable.

The resin powder (C) has an average particle size of 20 to 60.
μm, and the average particle diameter is 30 to 50 μm.
m is preferred. If the average particle size is less than 20 μm, the design of the coating film and the contact trace resistance are not sufficient.
If it exceeds 0 μm, the design of the coating film will be reduced, and the coating workability will also be reduced.

The compounding amount of the resin powder (C) is 1 to 20 parts by weight, preferably 3 to 20 parts by weight, based on 100 parts by weight of the total amount of the film-forming resin component composed of the polyester resin (A) and the crosslinking agent (B). To 10 parts by weight. If the amount of the resin powder (C) is less than 1 part by weight, the design, the contact mark resistance and the abrasion resistance are not sufficiently improved, while if it exceeds 20 parts by weight, the processability and adhesion of the coating film are poor. descend.

Curing Catalyst (D) The curing catalyst (D) is optionally blended to promote the reaction between the polyester resin (A) and the crosslinking agent (B). Are appropriately selected and used according to the type of the stencil.

When the crosslinking agent (B) contains a melamine resin, particularly a low-molecular-weight melamine resin of methyl etherification or a mixed etherification of methyl ether and butyl ether, a sulfonic acid compound or a sulfonic acid compound is used as a curing catalyst. Amine neutralized products are preferably used. Representative examples of the sulfonic acid compound include p-toluenesulfonic acid,
Dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid and the like can be mentioned. The amine in the amine-neutralized sulfonic acid compound may be any of a primary amine, a secondary amine and a tertiary amine. Among these, from the viewpoint of the stability of the paint, the reaction promoting effect, and the physical properties of the obtained coating film,
An amine neutralized product of p-toluenesulfonic acid and / or an amine neutralized product of dodecylbenzenesulfonic acid are preferred.

When the crosslinking agent (B) is a blocked polyisocyanate compound, a curing catalyst which promotes the dissociation of the blocking agent of the blocked polyisocyanate compound as the crosslinking agent is suitable. For example, tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide, 2-ethyl An organic metal catalyst such as lead hexanoate may be used.

When these curing catalysts are blended, they are usually used in an amount of 100 parts by weight of the total amount of the film-forming resin component composed of the polyester resin (A) and the crosslinking agent (B).
It is blended in the range of 0.1 to 2.0 parts by weight. When the curing catalyst is a sulfonic acid compound or an amine neutralized sulfonic acid compound, the curing catalyst amount means an amount converted to a sulfonic acid amount, and when the curing catalyst is an organometallic catalyst, the solid content is Means

The coating composition of the present invention can be substantially composed of a polyester resin (A), a crosslinking agent (B), a resin powder (C), and a curing catalyst (D) used as required. And, if necessary, further lubricating agents, inorganic matting agents, organic solvents, coloring pigments; luminosity such as aluminum powder, copper powder, nickel powder, mica powder coated with titanium oxide, mica powder coated with iron oxide, and brilliant graphite Pigments; which may contain additives known per se for paints, such as antifoaming agents and coating surface conditioners.

As the above-mentioned lubricant, any known lubricant in the field of paints can be used as long as it can impart lubricity to the surface of the coating film. Polyolefin wax such as polyether-modified silicone oil, higher fatty acid ester-modified silicone oil, higher alkoxy-modified silicone oil and other modified silicone oils; paraffin wax such as microcrystalline wax; montan wax, lanolin wax, carnauba wax,
Examples include fatty acid ester waxes such as beeswax and whale wax. Among them, polyethylene wax is preferred.

As the inorganic matting agent, any inorganic matting agent used in the field of paints can be used as appropriate, and examples thereof include silica fine powder. By blending the inorganic matting agent, it is possible to obtain a coating film having a uniform unevenness, which is advantageous from the viewpoint of design.

The organic solvent is added as necessary to improve the coating properties of the composition of the present invention, and includes the polyester resin (A), the crosslinking agent (B) and the curing catalyst (D). Those that can dissolve or disperse the components can be used.Specifically, for example, toluene, xylene, hydrocarbon solvents such as high boiling petroleum hydrocarbons, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ketone solvents such as isophorone, Ester solvents such as ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate and diethylene glycol monoethyl ether acetate; alcohol solvents such as methanol, ethanol, isopropanol and butanol;
Examples thereof include ether alcohol solvents such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and diethylene glycol monobutyl ether. These can be used alone or as a mixture of two or more.

Examples of the color pigments which can be used as required include those usually used in the field of paints, for example, white pigments such as titanium white and zinc white; cyanine blue, cyanine green, azo series and quinacridone series. Organic red pigments, organic yellow pigments such as benzimidazolone-based, isoindolinone-based, isoindoline-based, and quinophthalone-based; and inorganic coloring pigments such as titanium yellow, red iron black, carbon black, graphite and various calcined pigments.

The composition of the present invention can be applied to various substrates such as metal plates, plastics and glass plates, for example, directly or via a primer coating.

Hereinafter, the coated metal sheet of the present invention will be described.

The coated metal sheet of the present invention is obtained by forming the above-mentioned cured coating film of the coating composition of the present invention on a metal plate via a polyester-based primer coating film.

Examples of the metal plate used as the object to be coated include a cold-rolled steel plate, a zinc-plated steel plate, and an aluminum plate. Among them, a zinc-plated steel plate can be preferably used. As galvanized steel sheet,
Hot-dip galvanized steel sheet, electro-galvanized steel sheet, iron-zinc alloy-plated steel sheet, nickel-zinc alloy-plated steel sheet, aluminum-zinc alloy-plated steel sheet (eg, “galvalume”, “galfan”), and the like Zinc phosphate treatment on galvanized steel sheet,
A chemical conversion-treated zinc-based plated steel sheet subjected to a chemical conversion treatment such as a chromate treatment can be given.

A primer coating film can be formed by painting and baking a polyester-based primer on the metal plate. Although the thickness of the primer coating is not particularly limited, it is usually 2 to 10 μm in dry film thickness.
It is about.

The polyester-based primer contains, as a main component, a polyester resin or a modified polyester resin, and, if necessary, a resin component containing a crosslinking agent such as an amino resin or a polyisocyanate compound.
It contains pigments, organic solvents, and other paint additives. Examples of the modified polyester resin include an epoxy-modified polyester resin and a urethane-modified polyester resin.

The primer coating film to be formed has a glass transition temperature of 40 to 100 ° C., preferably 50 to 90 ° C. If the glass transition temperature is less than 40 ° C., the coating film hardness as a total coating film and the abrasion resistance become insufficient,
In addition, the corrosion resistance and moisture resistance of the coating film are reduced, and when the glass transition temperature exceeds 100 ° C., the workability of the coating film is reduced.

The method of applying the coating composition of the present invention on the primer coating film is not particularly limited, and can be carried out using, for example, roll coating, curtain flow coating, dip coating, spray coating, or the like. The coating film thickness at that time is usually 5 to 30 μm in dry film thickness, especially 10 to 2 μm.
A range of 5 μm is preferred. The average particle size of the resin powder (C) in the paint of the present invention is 1.0 to 5.0 times, preferably 1.5 to 4.0 times, the average thickness of the formed top coat. Appropriate.

The curing conditions of the coating composition of the present invention can be appropriately selected from the baking conditions under which the coating is cured.
In the case of coil coating in which a long, continuously coated metal plate that moves continuously is continuously coated by roll coating or the like, the material ultimate temperature (PMT) is usually 16
Within a range of 15 to 90 seconds at 0 to 260 ° C, especially PMT19
Conditions within the range of 0 to 230 ° C and 20 to 60 seconds are suitable.

[0055]

The present invention will be described more specifically with reference to the following examples. Hereinafter, “parts” and “%” are based on weight.

Examples 1 to 8 and Comparative Examples 1 to 7 Coatings were prepared according to the composition shown in Table 1 below to obtain respective top coatings.

The amounts of the polyester resin and the cross-linking agent in Table 1 are indicated by the weight of the solid content.
The sulfonic acid-based curing catalyst was expressed in terms of weight in terms of the amount of each sulfonic acid compound, and the organotin-based curing catalyst was expressed in terms of solids weight. In addition, at the time of making the top coats of Examples and Comparative Examples into a paint, titanium white as a white pigment was dispersed. In addition, a mixed solvent of cyclohexanone / Swazol 1500 (manufactured by Cosmo Oil Co., Ltd., aromatic petroleum-based high boiling point solvent) = 60/40 (weight ratio) was used for adjusting the viscosity of the paint. When painting,
The paint viscosity was adjusted to about 90 seconds (25 ° C) with a Ford cup # 4.

[0058]

[Table 1]

(Note) in Table 1 has the following meanings, respectively.

The polyester resins indicated by (* 1) to (* 3) in Table 1 are all polyester resins manufactured by Toyobo Co., Ltd., and the polyester resins indicated by (* 4) are manufactured by Bayer Corporation. It is a polyester resin and has properties shown in Table 2 below.

[0061]

[Table 2]

(* 5) Cymel 303: low molecular weight methyl etherified melamine resin, manufactured by Mitsui Cytec Co., Ltd., having a content of hexakis (methoxymethyl) melamine of 60% by weight or more. (* 6) Desmodur BL-3175: a blocked polyisocyanate compound manufactured by Sumitomo Bayer Urethane Co., Ltd.

(* 7) Nail cure 5225: Aqueous neutralized solution of dodecylbenzenesulfonic acid manufactured by King Industries, USA. (* 8) Nailure 2500X: Aqueous neutralized solution of paratoluenesulfonic acid, manufactured by King Industries, USA. (* 9) Formate TK-1: An organotin-based curing catalyst manufactured by Takeda Pharmaceutical Co., Ltd.

(* 10) Olgasol 2002ES-3: Nylon 12 having an average particle diameter of about 30 μm, manufactured by Ato Shimmy, France
Resin powder. (* 11) Olgasol 2002ES-5: Nylon 12 resin powder having an average particle size of about 50 μm, manufactured by Ato Shimmy, France. (* 12) TEXTURE5378W: Shamrock Technologies INC.
(Shamrock Technologies Inc.), a polypropylene resin powder having an average particle diameter of about 25 μm. (* 13) TEXTURE5382D: Shamrock Technologies INC.
(Shamrock Technologies, Inc.) polypropylene resin powder having an average particle size of about 40 μm. (* 14) Olgasol 2002EX-D: Nylon 12 resin powder having an average particle diameter of about 10 μm, manufactured by Ato Shimmy, France. (* 15) X-52-1032: silicone resin powder, manufactured by Shin-Etsu Silicone Co., Ltd., average particle size about 20 μm. (* 16) Tuftic A-20: manufactured by Toyobo Co., Ltd., polyacrylonitrile resin powder, average particle size about 28 μm.

(* 17) Toshiba glass beads GB402T: hollow glass powder, manufactured by Toshiba Corporation.

(* 18) Sylysia 446: an inorganic matting agent which is a fine silica powder manufactured by Fuji Silysia Ltd.

(* 19) High Flat TE-10P-K-5: polyethylene wax manufactured by Gifu Shellac Works.

APPLICATION EXAMPLES 1 to 21 KP color 863, manufactured by Kansai Paint Co., Ltd., on a 0.5 mm thick electrogalvanized steel sheet subjected to a chromate treatment.
0 primer (epoxy-modified polyester primer for pre-coated steel sheet, Tg point of the coating film is 52 ° C.) so that the dry film thickness is about 4 μm,
C. for 30 seconds to obtain a primer-coated steel sheet. On the primer-coated steel sheet, each of the overcoats obtained as described above is applied by a bar coater so as to have a dry film thickness of about 18 μm, and baked for 45 seconds so that the maximum temperature of the material reaches 220 ° C. A coated steel plate was obtained. Various tests were performed on the obtained coated steel sheet. Application Examples 13 to 1
9 is an application example for comparison. Application examples 20 and 21
Is an application example when the glass transition temperature of the primer coating film is out of the range of 40 to 100 ° C.

Table 3 shows the test results.

[0070]

[Table 3]

The primer species in Table 3 have the following meanings.

KP8630pr: "KP Color 8630 Primer" manufactured by Kansai Paint Co., Ltd., epoxy-modified polyester resin-based primer for pre-coated steel sheet, Tg point of coating film is 52 ° C. KP8692pr: “KP Color 8692 Primer” manufactured by Kansai Paint Co., Ltd., epoxy-modified polyester resin-based primer for pre-coated steel sheet, Tg point of coating film is 90 ° C. KP8690pr: "KP Color 8690 Primer" manufactured by Kansai Paint Co., Ltd., epoxy-modified polyester resin-based primer for pre-coated steel sheet, Tg point of coating film is 65 ° C. KP8620pr: "KP Color 8620 Primer" manufactured by Kansai Paint Co., Ltd., polyester resin-based primer for pre-coated steel sheet, Tg point of coating film is 81 ° C. KP8600pr: "KP Color 8600 Primer: Kansai Paint Co., Ltd., polyester resin-based primer for pre-coated steel sheet, Tg point of coating film is 37 ° C. KP8464pr:" KP Color 8644 Primer: Kansai Paint Co., Ltd., for pre-coated steel sheet Epoxy resin-based primer,
The Tg point of the coating film is 106 ° C.

The tests in Table 3 were performed according to the following test methods.

Test Method Appearance of Painted Surface: The appearance of the painted surface (30 cm × 30 cm) was visually observed, and the uniformity of unevenness was evaluated according to the following criteria.

◎: There is no unevenness in unevenness, and the reflected light is uniform. ：: 1 to 4 places where the reflected light is different from the surroundings Δ: 5 to 10 places where the reflected light is different from the surroundings X: 11 places where there is no unevenness or reflected light is different from the surroundings
There are more than two places.

Pencil hardness: JIS
A pencil scratch test specified in K-5400 8.4.2 (1990) was performed, and evaluation by scratches was performed.

Folding workability: In a room at 20 ° C., the test plate was bent 180 ° with the painted surface outside, and the T number at which no cracks occurred in the bent portion was visually evaluated and indicated. The T number is 1 without anything inside the bend.
0T when 80 ° bending is performed, 1T when one plate having the same thickness as the test plate is sandwiched and 2T when two plates are bent,... The case was 6T.

Adhesion: JIS K-5400 8.5.
2 (1990) According to the crosscut-tape method, 11 parallel vertical and horizontal straight lines are drawn at 1 mm intervals on the surface of the coating film of the test plate so as to reach the substrate with a cutter knife, and the distance is 1 mm. 100 × 1 mm squares were created. A cellophane adhesive tape was adhered to the surface, and the degree of peeling of the squares when the tape was abruptly peeled was observed and evaluated according to the following criteria. ：: No peeling of the coating film was observed at all. Δ: The coating film was slightly peeled, but 90 or more squares remained. ×: The coating film was considerably peeled, and the number of remaining squares was less than 90.

Abrasion resistance: The coating film of the coated plate was tested for abrasion resistance by the following sandpaper method and nail resistance test method. (1) Sandpaper method: A water-resistant abrasive paper # 1500 (manufactured by Sankyo Rikagaku Co., Ltd.) was attached to a friction fastness tester (manufactured by Daiei Chemical Seiki Seisakusho), and the coated paper was contacted with a load of 500 g and reciprocated 20 times. Thereafter, the coating film surface was visually evaluated according to the following criteria. ◎: No scar is observed on the surface of the coating film ○: Scar is observed on the surface of the coating film, but the scar is not conspicuous △: A scar is observed on the surface of the coating film, and the scar is considerably noticeable ×: A remarkable scar is observed on the surface of the coating film (2) Nail scratch resistance: The degree of scratching of the coating film was evaluated by visual inspection according to the following criteria when a nail was stood on the coating film surface and reciprocated 10 times. ◎: No scar is observed on the surface of the coating film ○: Scar is observed on the surface of the coating film, but the scar is not conspicuous △: A scar is observed on the surface of the coating film, and the scar is considerably noticeable ×: A remarkable scar is observed on the surface of the coating film Is seen.

Contact Trace Resistance: The coating trace of the coated plate was tested for contact trace resistance by the following heating and pressurizing resistance and suction cup resistance. (1) Heating and pressurization resistance: A polyethylene terephthalate film (PET) having a size of 20 mm × 20 mm
Film) was placed thereon, a load was applied thereon so as to be 1 kg / cm ² , the mixture was heated at 60 ° C. for 2 hours, and the coated surface was visually evaluated according to the following criteria. ：: No trace of the PET film was observed at all. △: Part of the edge of the PET film was recognized. ×: The trace of the PET film was increased in gloss and clearly recognized. (2) Sucker resistance: Lec Co., Ltd. And a clear suction cup (mini) attached to the coating surface and heated at 60 ° C for 3 hours.
The coated surface was visually evaluated according to the following criteria. ：: No trace of suction cup is observed. Δ: Slight trace of suction cup is observed. X: Remarkable trace of suction cup is recognized.

[0081]

The coating composition of the present invention is obtained by combining a specific polyester resin with a specific crosslinking agent and blending the resin system with a polyamide resin powder and / or a polypropylene resin powder, and has good hardness and workability. It is a design having uniform unevenness, excellent contact resistance, excellent scratch resistance,
It is possible to form a coating film having a well-balanced performance which has not been achieved so far.

By forming a coating film of the coating composition of the present invention on a metal plate via a (modified) polyester resin-based primer coating film having a Tg of 40 to 100 ° C., the above-mentioned properties, particularly hardness and workability, are obtained. A coated metal plate having a well-balanced overall coating film performance can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 175/06 C09D 175/06 // C08L 75/06 C08L 75/06

Claims (5)

[Claims] (A) a number average molecular weight of 2,000 to 35,
000, glass transition temperature -25 ° C to 35 ° C, hydroxyl value 3
Total amount of a film-forming resin component consisting of 65 to 95 parts by weight of a hydroxyl group-containing polyester resin of 100 to 100 mgKOH / g and 5 to 35 parts by weight of (B) at least one crosslinking agent selected from amino resins and blocked polyisocyanate compounds. 100 parts by weight, (C) 1 to 20 parts by weight of at least one kind of resin powder selected from polyamide resin powder and polypropylene resin powder and having an average particle diameter of 20 to 60 μm, and if necessary, (D) A) a coating composition comprising 0.1 to 2.0 parts by weight of a curing catalyst; 2. The paint according to claim 1, wherein the crosslinking agent is a melamine resin curing agent which is a methyletherified melamine resin or a mixed melamine resin of a methyletherified melamine resin and a butyletherified melamine resin. Composition. 3. The coating composition according to claim 1, further comprising a lubricant. 4. The coating composition according to claim 1, further comprising an inorganic matting agent. 5. The method according to claim 1, wherein the glass transition temperature is between 40 and 1 on the metal plate.
A coated metal sheet, comprising a cured top coat of the coating composition according to claim 1 formed through a polyester resin-based or modified polyester resin-based primer coating at 00 ° C.