JP3099427B2 - Weldable black steel plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to home appliances, office equipment,
The present invention relates to a black steel plate which is suitable for copying machines, automobiles, building materials and the like and which can be welded and has an excellent black appearance.

[0002]

2. Description of the Related Art Recently, in the fields of home electric appliances and office equipment,
There is an increasing need for a black steel plate that can be welded and has an excellent appearance, which is obtained by performing a continuous and short-time treatment on a steel plate such as zinc or zinc alloy plating. For this reason,
Various attempts have been made to develop a blackening treatment method, a blackening treatment liquid, or a black steel sheet obtained therefrom.

Conventionally, there are the following methods for forming a black film on a steel sheet. (A) A method of applying a resin film containing a black pigment such as carbon black to a film thickness of several tens μm by spraying or a roll coater. (B) A method of forming a black film by reacting or electrolyzing a plating layer itself formed in advance as a film. (1) A method of obtaining a black chromate film by a chromate bath containing Ag ions (Japanese Patent Application Laid-Open No. 58-193376)
issue). (2) A method of electrodepositing a black resin film containing carbon black as a main component (JP-A-56-62996). (3) A method of performing anodizing after electroplating Zn-Co, Ni or Mo alloy (Japanese Patent Publication No. 61-38276).
issue). (4) A method of obtaining a black appearance by subjecting a Zn—Ni alloy-plated steel sheet to immersion, spraying, or anodizing in a bath containing nitric acid or nitrate (Japanese Patent Publication No. Sho 62-30262).
issue). (5) A method of forming a black plating film by a cathode treatment (for example, JP-A-62-263959). (6) A method in which displacement plating is performed on Zn or Zn alloy plating to deposit a metal having a more noble potential (for example, JP-A-62-89879). (C) A method of applying a treatment liquid obtained by adding an organic dye to an aqueous solution of potash water to zinc or a galvanized surface for the purpose of corrosion resistance and adhesion (Japanese Patent Publication No. 55-30593).
issue).

[0004]

However, these prior arts have the following problems. First,
The method (a) is a general coating method, but welding is impossible because the coating thickness for the exterior is usually 10 μm or more in a single layer. Further, the black color imparting agent in the coating film is carbon black, and has a film thickness (0.2 to 3 μm) within a weldable range.
In the case of coating in m), even if the black pigment concentration is increased to the limit as a coating, the blackness is insufficient, and it is difficult to obtain a sufficient black coating with only the coating. That is, with the conventional black imparting agent, it was impossible to obtain sufficient blackness with a film thickness (0.2 to 3 μm) within a weldable range.

[0005] The various methods (b) also have the following problems. Of these methods, first, the method (1) involves high production costs because Ag ions are contained in the processing bath, and the processing time required for blackening is as long as several tens of seconds. ) Is unsuitable. (2)
In the method (1), the processability of the black film is not sufficient, and the black film has electric conductivity because carbon black is a conductive pigment, and as a result, the corrosion resistance is poor. Moreover, the blackness is also insufficient.

[0006] The methods (3) and (4) are not only uneconomical but also cause the metal ions eluted from the plating to not only be uneconomical but also to elute a part of the previously formed plating during the blackening treatment. However, this deteriorates the blackening treatment, and becomes a serious problem in continuous operation. The method (3) uses Z
The method is limited to n-Co, Ni, and Mo-based alloy plating, and the method (4) is limited to Zn-Ni alloy plating. Also,
The method (5) has a problem that the workability of the black film is not sufficient.

In the method (6), since the adhesion of the black film is not sufficient, and a metal having a higher potential is formed on a base metal (Zn or Zn alloy) plating, the corrosion resistance is low. Is reduced. Next, the method (c) is not aimed at providing a film having excellent blackness, nor is it intended to impart weldability since the thickness of the film is not specified.
Further, since potash water glass is used as a basic material of the film, the film after curing has insufficient lubricity at the time of press working, and is unsuitable for use in steel sheets for home appliances and office equipment.

The present invention has been made in order to solve the above-mentioned problems, and a conventional black coating film using a black pigment such as carbon black as a black-imparting agent (a coating film obtained by the method (a)). The first object of the present invention is to provide a black steel sheet that can provide an excellent black appearance within a range of a weldable film thickness in order to impart weldability that was not possible in the case of (1). By solving such a problem of the above method (a),
Conventional reaction or electrolysis method (method (b) above)
As described above, there is no problem of deterioration of the treatment bath or plating loss due to elution of metal ions, and no problem of limiting the base plating due to blackening. In addition, by using existing strip continuous coating and baking equipment, continuous processing can be performed in a short time. Another object of the present invention is to provide a black steel sheet which is not only weldable and excellent in black appearance but also excellent in corrosion resistance, adhesion and workability.

[0009]

In order to achieve such an object, the present invention has the following arrangement. (1) A chromate film having a chromium deposition amount (calculated as chromium metal) of 10 to 200 mg / m ² is provided on the surface of zinc or a zinc-based alloy plating, and a thermosetting resin is provided on the base of the chromate film. A weldable black steel sheet having a black coating having a thickness of 0.3 to 3.0 μm, which is a resin and is prepared by mixing 1 to 200 parts by weight of a black dye as a blackening agent with respect to 100 parts by weight of the base resin.

(2) Amount of chromium (in terms of metallic chromium) of 10 to 200 mg /
m ² chromate film, and a thermosetting resin is used as a base resin on the upper part of the chromate film.
1 to 20 parts by weight of a black dye as a black imparting agent
A weldable black steel sheet having a black film having a thickness of 0.3 to 3.0 μm and containing 0 part by weight and 1 to 100 parts by weight of a solid lubricant.

(3) The amount of chromium deposited on the surface of zinc or zinc-based alloy plating (calculated as chromium metal): 10 to 200 mg /
m ² chromate film, and a thermosetting resin is used as a base resin on the upper part of the chromate film.
1 to 20 parts by weight of a black dye as a black imparting agent
A weldable black steel sheet having a black film having a thickness of 0.3 to 3.0 μm, in which 0 part by weight and further 1 to 100 parts by weight of a particulate rust preventive pigment are blended.

(4) Amount of chromium deposited on the surface of zinc or zinc-based alloy plating (calculated as chromium metal): 10 to 200 mg /
m ² chromate film, and a thermosetting resin is used as a base resin on the upper part of the chromate film.
1 to 20 parts by weight of a black dye as a black imparting agent
0 part by weight, 1 to 100 parts by weight of a solid lubricant, and 1 to 100 parts by weight of a particulate rust preventive pigment.
A weldable black steel plate having a 3.0 μm black coating.

(5) In the black steel sheet of the above (2) or (4), as a solid lubricant, hydrocarbon compounds such as polyolefin wax, fluororesin compounds, fatty acid amide compounds, metal soaps, molybdenum disulfide A weldable black steel sheet containing one or more selected from the group consisting of metal sulfides such as, graphite, fluorinated graphite, boron nitride, and polyalkylene glycol.

(6) In the black steel sheet according to the above (3), (4) or (5), as the particulate rust preventive pigment, one or more kinds selected from the group consisting of a hardly soluble chromium compound and silica are used. Weldable black steel sheet including.

[0015]

The details of the present invention and the reasons for limiting the same will be described below. The black steel sheet of the present invention uses a zinc-plated or zinc alloy-plated steel sheet as a starting material, and has a chromate film on its surface.
Further, a black film made of a thermosetting resin-based composition in which a black dye is blended is provided on the upper portion. Here, the black dye in the present invention includes a dye that exhibits black by only the same kind of molecule due to the chemical structure of the molecule and a dye that exhibits black by mixing several kinds of dyes having different chemical structures of the molecule. It is a thing.

As a starting material, a zinc-based plated steel sheet includes:
Galvanized steel sheet, zinc-iron alloy plated steel sheet, zinc-nickel alloy plated steel sheet, zinc-manganese alloy plated steel sheet,
One or more elements such as Ni, Fe, Mn, Mo, Co, Al, and Cr are added to the plating components of zinc-aluminum alloy-plated steel sheet, zinc-cobalt-chromium alloy-plated steel sheet, and any of these steel sheets. Those added can be used. In addition, a steel sheet having a dispersion plating in which a particulate resin, silica, a chromium compound, or the like is co-deposited during any of the above platings can be used. Further, a composite plated steel sheet having two or more layers of the same or different types of the above-mentioned plating may be applied. For example, a plating film obtained by applying two or more layers of Fe—Zn alloy plating having different Fe contents can be used as a base.

From the viewpoint of blackness, a similar black film can be obtained irrespective of the type of the base steel sheet. Therefore, it is possible to use a hot-rolled steel sheet or a cold-rolled steel sheet having no plating film as a starting material. For the same reason, a stainless steel plate, an aluminum alloy plate, or a titanium alloy plate can be used as a material. However, considering the use of forming and unpainted as a black steel sheet for household appliances, from the viewpoint of performance such as cost and corrosion resistance, it is desirable that the starting material be the above-mentioned galvanized steel sheet. The starting material was limited to a galvanized steel sheet or a zinc-based alloy-coated steel sheet. As a method for plating these zinc-based plated steel sheets, any method that can be used, such as an electrolytic method, a melting method, or a gas phase method, can be adopted.

A chromate film is formed on the surface of the material-plated steel sheet by chromic acid treatment. In the black steel sheet of the present invention, extremely excellent corrosion resistance can be obtained by combining this chromate film with a black film containing a specific black imparting agent as described later. The chromate film has a chromium adhesion amount (dry) of 10 to 200 mg / m ² , preferably 30 to 80 mg / m ² (the above is converted to chromium metal). If the chromium adhesion amount exceeds 200 mg / m ² , workability and weldability tend to deteriorate. On the other hand, if the chromium adhesion amount is less than 10 mg / m ² , the coating may be uneven and the corrosion resistance may be deteriorated. It is preferable that hexavalent Cr be present in the chromate film. Hexavalent Cr ions have a repairing action and, when the steel sheet is damaged, act to suppress corrosion therefrom. Such a chromate treatment for the undercoat may be performed by any known method such as a reaction type, a coating type, and an electrolytic type.

The coating type chromate treatment solution contains a partially reduced chromic acid solution as a main component, and if necessary, a water-dispersible or water-soluble organic resin such as an acrylic resin and / or an organic resin such as an acrylic resin.
Alternatively, it contains silica (colloidal silica, fumed silica) having a particle size of several μm to several hundred μm. In this case, the ratio of trivalent Cr ions / hexavalent Cr ions is 1 /
1 to 1/3, pH 1.5 to 4.0 (more preferably 2 to 1/3)
To 3) are preferred. The ratio of trivalent Cr ions / hexavalent Cr ions is adjusted to a predetermined ratio using a general organic reducing agent (for example, sugars, alcohols, etc.) or an inorganic reducing agent. In addition, as a coating type chromate treatment, a roll coater method,
Any method such as an immersion method and a spray method may be used. In the coating type chromate treatment, a film is obtained by drying without washing after the chromate treatment. Drying without washing in this manner is performed by hexavalent Cr in ordinary washing with water.
This is because ions are removed, and the ratio of trivalent Cr ions / hexavalent Cr ions is stably maintained as it is, and the resin film formed on the upper portion suppresses excessive outflow of hexavalent Cr ions in a corrosive environment. However, the passivation effect can be effectively maintained over a long period of time, and high corrosion resistance can be obtained.

On the other hand, in the electrolytic type chromate treatment, a cathodic electrolysis treatment is performed in a bath containing chromic anhydride and one or more anions such as sulfuric acid, phosphoric acid fluoride or halogen oxyacid, followed by washing and drying. To form a film.
Comparing the chromate films obtained by the above two treatment methods, the coating type chromate is superior in corrosion resistance because it contains a larger amount of hexavalent chromium in the film than the electrolytic type chromate. When subjected to heat treatment, the film becomes dense and strong, so that the corrosion resistance becomes better than that of electrolytic chromate. On the other hand, the electrolytic type chromate has the advantages that the degree of completion of the film is high irrespective of the presence or absence of the heat treatment, and has the advantage that the control of the amount of the film adhered is easy. In consideration of corrosion resistance, coating type chromate is most desirable.

Next, the components of the black film will be described. The most distinctive feature of the black film of the present invention is that a thermosetting resin is used as a base resin, and a black dye is contained in the base resin. Further, in the present invention, in addition to the above components, a solid lubricant can be contained for the purpose of improving the processability of the black film, and a rust preventive pigment can be contained for the purpose of improving the corrosion resistance. In the following description, the blackness of the black film is evaluated by the lightness L value. As for the L value, the smaller the value, the better the blackness, and the target of the black film in the present invention is L ≦ 25, preferably L ≦ 20, and more preferably L ≦ 15. The L value was measured using a Suga tester.
The measurement was performed using a multi-source light spectrophotometer (model MSC) manufactured by Co., Ltd.

The function required as a blackening agent is that a film having a weldable thickness (3 μm or less) can exhibit a sufficient degree of blackness. Moreover, when the black imparting agent is mixed with the base resin at a mixing ratio that provides sufficient blackness, other properties required for the black coating,
For example, there should be no material that adversely affects workability, corrosion resistance, and the like.

Colorants generally used can be broadly classified into inorganic pigments, organic pigments, and dyes. Of these, when inorganic pigments and organic pigments are used in a thin coating film of several μm or less,
The hiding power of the pigment is important for blackness. Carbon black is a typical example of a black pigment for inorganic pigments, and is most frequently used among black pigments because of its low cost and the like, and there are many grades according to the purpose. However, unlike carbon black having a film thickness of several tens of μm as in ordinary paints, the blackness of carbon black is not sufficient for a thin film having a thickness of 3 μm or less, which is the target of the present invention. It is not suitable because it is insufficient and, furthermore, is a conductive pigment, so that the black film has electrical conductivity and the corrosion resistance of the steel sheet is inferior. Further, other black inorganic pigments such as iron oxide and titanium black have insufficient blackness.

As a typical black organic pigment, aniline black is typical. However, since the hiding power is also inferior, sufficient blackness cannot be obtained. As other black organic pigments, there is perylene black, which cannot similarly provide a sufficient degree of blackness. Even when two or more of the above-mentioned inorganic pigments and organic pigments are combined, the blackness is still insufficient.

On the other hand, the present inventors have found that a black dye can impart excellent blackness even with a thin film.
Inorganic pigments and organic pigments are particles, and it is considered that the aggregate of particles absorbs visible light to exhibit black color.Therefore, in order to impart a good degree of blackness, a certain thickness of the aggregate of particles, That is, it is considered that the thickness of the film is required. On the other hand, the black dye is soluble in water or an organic solvent, so that it can be dispersed in a very fine state at a molecular level and densely in a film, and therefore, excellent blackness can be obtained even in a thin film. It can be given.

It is said that there are several thousands of dyes on the market at present as trade names. These are roughly classified into two types of classification methods, namely, a chemical structural classification method (1) and a dye method. Classified by a practical classification method (2) based on characteristics (for example, "Organic Chemistry Handbook")
Published by Gihodo, edited by the Society of Synthetic Organic Chemistry). In the classification method (1) based on the chemical structure, it is classified according to the main structure that causes color development in the dye molecule, and is classified into nitroso dye, nitro dye, azo dye (monoazo dye, disazo dye, trisazo dye, tetrakisazo dye), anthraquinone dye ,
There are indigo dye, azine dye, cyanine dye, phthalocyanine dye, stilbene dye, sulfur dye, triazole dye, triphenylmethane dye, acridine dye, diphenylmethane dye, oxazine dye and the like. On the other hand, in the practical classification method (2) based on the dye properties, direct dyes, acid dyes, basic dyes, acid mordant dyes, metal complex dyes, sulfur dyes, vat dyes, IZOC dyes, disperse dyes, reactive dyes, oxidation dyes Dyes, fluorescent brightening dyes, oil-soluble (organic solvent-soluble) dyes and the like.

According to the above classification, for example, dyes classified into acidic dyes by the classification method of (2) are further classified into azo dyes (monoazo, disazo, trisazo, tetrakisazo) by the classification method of (1). , Anthraquinone dye, triphenylmethane dye, azine dye and the like. On the other hand, color is an important characteristic of the dye, -CH = CH in its chemical structure -, - N = N-like groups having an unsaturated bond and (chromophore), -NH _2, -OH, etc. Groups having a free electron pair (auxochromophore) absorb light of a specific wavelength, and light of a wavelength that is not absorbed is captured by the naked eye as the color of the substance. Dyes of various colors will be present. See “COLOUR I” below.
NDEX classifies these colors into yellow, orange, red, violet, blue, green, brown, and black.

By the way, "THE SOCIETY OF DYERS AND C
OLOURISTS '' and `` AMERICAN ASSOCIATION OF TEXTILE CHE
MISTS AND COLOURISTS "by" COLOUR INDEX (THIRD
EDITION Vol.1-8) ”describes the classification, structure, properties, uses, etc., to which each of the commercially available dyes belongs, and each dye is described in“ CIGe INDEX ”as“ CIGe
neric Name ". In other words, this "COLOUR INDEX" classification method divides commercially available dyes into practical categories, which are almost the same as those in the above (2), and then displays the color categories. The dyes having the same chemical structure are classified (numbered in order from 1).
Those that are clear up to the specific structural formula represent the structure `` CI
Constitution Number ”is described, but even if it is not, most of them are classified as described in (1) above.
For example, chemical structural classifications of azo (monoazo, disazo, etc.), anthraquinone, azine and the like are described.

For example, a black dye in the class of acid dyes is indicated by a classification “CI Acid Black”,
Among them, "CI Acid Black 1" has a specific chemical structure of disazo dye, "CI Acid Black 2" has a specific chemical structure of azine dye, "CI Acid Black 3"
Are classified as having a specific chemical structure of a disazo dye, and the color, characteristics, application, and the like are described for each. This "CI Generic Name" can be mutually compared with the trade name of a commercially available dye.

As a result of the study by the present inventors, it has been found that by blending the above-mentioned black dye with a thermosetting resin, good blackness can be obtained even as a weldable thin film (3 μm or less). . However, in the present invention, "CO
It goes without saying that dyes that are not registered in "LOUR INDEX", for example, newly developed dyes that have not been registered, or a mixture of a plurality of dyes can be used.

The black dye may be a dye having any structure classified according to the category (1), for example, azo dye, azo-methine dye, quinoline dye, ketone imine dye, fluorone dye, nitro dye, xanthene dye, acenaphthene dye Quinophthalone dye, anthraquinone dye, aminoketone dye, methine dye, perylene dye, coumarin dye, perinone dye, triphenyl dye, triallylmethane dye, phthalocyanine dye, inclophenol dye, azine dye, and the like. Two or more dyes can be used.

The black dye belongs to “Black” in the color classification “COLOUR INDEX”. However, a black film may be formed by mixing dyes of, for example, three colors of yellow, red, and purple by utilizing the conventionally known principle of subtractive color mixing. That is, as described above, as the black dye applied to the present invention, not only those that exhibit black with only the same kind of molecule due to the chemical structure of the molecule, but also that several kinds of dyes with different chemical structures of the molecule are mixed. Some of them have a black color. Therefore, by utilizing the principle of subtractive color mixture, it is possible to apply a dye obtained by mixing several coloring dyes belonging to one or more of the above-mentioned dyes into a black dye. Also, among the above dyes, black azo dyes are particularly inexpensive and can obtain good blackness.

Further, the present inventors have added the water-soluble azo metal complex dye which is one of the black azo dyes, so that the blackness is excellent, and the light fastness and corrosion resistance are higher than other dyes. It was found that an excellent black film was obtained.

This dye is characterized by a complex compound of one atom of metal to two molecules of azo dye (2: 1 type metal complex salt) or a complex compound of one atom of metal to one molecule of azo dye (1: 1). For structural reasons considered to be (type 1 metal complex salt), stability to light (light fastness) is superior to other dyes, and blackness is superior to other dyes. Metals that can form complex salts with dyes are C
r, Co, Cu, Fe, Al, etc.
There are many complex salts. Examples of the black azo metal complex dye include, among the above-mentioned classification (2), black acid dyes (Acid Black), black direct dyes (DirectBlack), black mordant dyes (Mordant Black), Some belong to the classification of organic solvent-soluble black dyes (Solvent Black).

1) "CI Acid Black": CI Acid Black 8, 43, 49, 51, 52, 52:
1,53,55,57,60,63,65,71,8
2,84,92,98,99,107,108,11
4,115,118,119,120,121,12
2,124,129,132,133,134,13
5,136,137,138,139,140,14
7,148,149,150,151,153,15
4,155,157,158,159,164,16
5,168,170,171,172,174,17
6,178,180,181,183,184,18
5,187,188,192,194,195,19
8, 199, 207, 211, 213, 215, 21
6,217,218,220,222,223,22
5,226,227 2) "CI Direct Black": CI Direct Black 57, 109, 116, 130, 1
42,143,144 3) "CI Mordant Black": CI Mordant Black 9
0 4) “CI Solvent Black”: CI Solvent Black 6, 22, 23, 25, 28, 2
9,30,34,35,36,37,39,40,4
1,42,43,45,47,48,49

As described above, black azo metal complex dyes not registered in "COLOUR INDEX", for example, newly developed dyes which have not been registered yet, and mixtures of plural kinds of dyes, It goes without saying that a mixture containing at least one black metal complex dye in the mixture can be used. When such a black azo-based metal complex dye is blended as a blackening agent in a black film, a uniform and excellent black appearance is exhibited even in a thin film (up to 3 μm) in a weldable range, and the light fastness of the dye itself is further improved. Is excellent, there is no problem even when a black steel plate is used for home appliances, office equipment and the like illuminated by various light sources.

A black azo dye which is not a metal complex salt with a black azine dye is inferior to the above black azo metal complex dye, but has excellent light fastness as compared with a black mordant dye or the like. Further, since the production unit is about 50 to 80% of the black azo metal complex dye, the raw material cost of the black film can be reduced as compared with a black steel sheet using the black azo metal complex salt dye as a blackening agent. There is an advantage that can be.

The black film to which the black dye is added has excellent corrosion resistance as described above, and the corrosion resistance is far superior to that of a black film containing a pigment as a black-imparting agent. This is because the black dye is non-conductive, the black dye is uniformly and densely distributed in the black film at the molecular level,
The dye itself has a function as a passive film. The black dye uniformly and densely distributed in the black film at the molecular level prevents ions from penetrating into the film and improves the barrier effect of the film. It is considered something.

The steel sheet having such a black coating has a barrier effect due to the formation of a passivation film of the base chromate (action of trivalent Cr ions) and an anticorrosion effect due to the barrier effect of the resin film itself. In addition, the above-described barrier effect of the black dye makes the corrosion resistance higher, and furthermore, the self-healing action of repairing the defects of the passive film by hexavalent Cr ion → trivalent Cr ion of the base chromate, and the base Zn
High corrosion resistance can be obtained due to factors such as good adhesion between the system plating, the chromate film and the black film.

Further, as shown in Example (6), which will be described later, by using an azo-based chromium complex dye as the black azo-based metal complex dye, in particular, the trivalent Cr ion and the base chromate can be used. Extremely excellent corrosion resistance, which is presumed to be a synergistic effect, is obtained. This is considered to be because the black azo metal complex salt dye containing trivalent Cr ions is stably present as a passive film, and the barrier effect is further improved. For these reasons, the black azo-based metal complex dye is most preferably one in which the metal forming the complex is trivalent Cr ion (black azo-based chromium complex dye).

Since the dye easily dissolves in a solvent, it can be made into a black film composition by mixing with a thermosetting resin. And when it is blended as a black imparting agent in the black film as described above, a uniform and excellent black appearance is exhibited even with a thin film (〜3 μm) within a weldable range. In addition, unlike the conventional etching type, black treatment involving reactions such as electrolytic treatment and displacement plating, the biggest advantage of the coating treatment is that there is no deterioration of the bath due to the treatment and the type of base plating is not limited. Can also be used.

Next, in the black film of the present invention, the mixing ratio of the black dye to 100 parts by weight of the base resin is from 1 to 20.
0 parts by weight, preferably 4 to 120 parts by weight. If the amount is less than 1 part by weight, the coloring effect of the black dye is poor.
When the amount exceeds the weight part, undissolved dye remains, which adversely affects the adhesion. Also, the thickness of the black film is 0.3 ~
3.0 μm, desirably 0.7 to 2.5 μm. When the film thickness is less than 0.3 μm, the coloring effect of the black dye is poor,
On the other hand, if it exceeds 2.5 μm, the spot weldability decreases,
In particular, when the thickness exceeds 3.0 μm, the weldability is significantly reduced.

The base resin of the black coating of the steel sheet of the present invention is a thermosetting resin. The reason why the base resin is defined as such a resin is that when a thermoplastic resin is used, a problem occurs in the scratch resistance of the formed black film. Examples of the thermosetting resin include an acrylic copolymer resin, an alkyd resin, an epoxy resin, a polybutadiene resin, a phenol resin, a polyurethane resin, a fluororesin, a mixture of two or more of these resins, and other monomers. And a modified derivative with another resin. Among them, acrylic copolymer resin, alkyd resin, epoxy resin, fluororesin and the like are preferable.

The acrylic copolymer is a resin synthesized by a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, or the like using a normal unsaturated ethylenic monomer, and is a methacrylate-based resin. An essential component is a hard monomer such as acrylonitrile, styrene, acrylic acid, acrylamide, and vinyltoluene, and an unsaturated vinyl monomer is appropriately added for the purpose of imparting resin hardness, flexibility, and crosslinkability. Obtained by blending. Further, this resin may be modified by another alkyd resin, epoxy resin, phenol resin or the like. Further, as the alkyd resin, a known alkyd resin obtained by a usual synthesis method can be used, for example, an oil-modified alkyd resin,
Rosin-modified alkyd resin, phenol-modified alkyd resin, styrenated alkyd resin, silicon-modified alkyd resin, acryl-modified alkyd resin, oil-free alkyd resin (polyester resin) and the like can be mentioned.

Epoxy resins include straight epoxy resins such as epichlorohydrin type and glycidyl ether type, fatty acid-modified epoxy resin (epoxy ester resin), polybasic acid-modified epoxy resin, acrylic resin-modified epoxy resin, alkyd (or polyester) ) Modified epoxy resin, polybutadiene-modified epoxy resin, phenol-modified epoxy resin, amine or polyamine-modified epoxy resin, urethane-modified epoxy resin and the like are used. Known predetermined curing agents are used for these resins. Examples of the curing agent include melamine, block isocyanate, and urea.

The above-described black coating of the steel sheet of the present invention has sufficient properties as it is, but more excellent properties can be obtained by adding the additives described below.

First, it is desirable to add a solid lubricant to the coating composition in order to impart good self-lubricating properties to the black coating. Examples of the solid lubricant applicable to the present invention include the following. -Hydrocarbon lubricants: For example, natural paraffin, synthetic paraffin, microwax, polyethylene wax, chlorinated hydrocarbon and the like. -Fluororesin: For example, polyfluoroethylene resin, polyvinyl fluoride resin, polytetrafluoroethylene resin, polyvinylidene fluoride resin and the like. -Fatty acid amide-based lubricant: For example, stearic acid amide, palmitic acid amide, methylene bisstearamide, ethylene bisstearamide, oleic acid amide, esylic acid amide, alkylenebisfatty acid amide and the like. -Metal soaps: For example, calcium stearate, lead stearate, calcium laurate, calcium palmitate and the like. -Metal sulfides: molybdenum disulfide and tungsten disulfide. -Others: graphite, fluorinated graphite, boron nitride, grease, alkali metal sulfate, etc.

The solid lubricant is used in an amount of 1 to 100 parts by weight, preferably 3 to 60 parts by weight, based on 100 parts by weight of the thermosulfide resin.
It is blended in the range of parts by weight. If the compounding amount is less than 10 parts by weight, particularly less than 1 part by weight, the effect of improving the lubrication of the black film by adding the solid lubricant is poor. On the other hand, if it is more than 60 parts by weight, especially more than 100 parts by weight, It is not suitable because the strength of the black film is reduced and a part of the film adheres to the press mold.

The black film obtained by applying the black film composition comprising the base resin and the black dye has sufficient corrosion resistance due to the synergistic effect of the base plating and the chromate film. In order to further improve the corrosion resistance in
A rust-preventive pigment can be added to the black coating composition, whereby more excellent corrosion resistance is obtained, and the use of the black steel sheet is also widened.

As the rust preventive pigment, one or more kinds selected from hardly soluble chromates and silica are used. Barium chromate (B
aCrO ₄ ), strontium chromate (SrCr)
O ₄ ), lead chromate (PbCrO ₄ ), zinc chromate (Z
_{nCrO 4 · 4Zn (OH) 2} ), calcium chromate (CaCrO _4), zinc chromate potassium (K ₂ O · 4Z
nO.4CrO ₃ .3H ₂ O), silver chromate (AgCrO)
₄ ) There is.

When a resin soluble in an organic solvent is used as a base resin, hydrophobic silica is effective in terms of compatibility with an organic solvent (ease of compatibility). Colloidal silica is used as the hydrophobic silica. Hydrophobized and fumed silica may be mentioned. In particular,
Colloidal silica dispersed in an organic solvent dispersed in a solvent such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, ethyl cellosolve, ethylene glycol (for example,
OSCAL 1132, 123 manufactured by Catalyst Chemical Industry Co., Ltd.
2,1332,1432,1532,1622,172
2,1724), silica whose surface has been hydrophobized with an organic solvent or a reactive silane compound, that is, hydrophobic ultrafine silica (for example, R97 manufactured by Nippon Aerosil Co., Ltd.)
4, R811, R812, R805, T805, R20
2, RY200, RX200, etc.). Such hydrophobic silica is stably dispersed in a base resin soluble in an organic solvent.

When a water-soluble or water-dispersible resin is used as the base resin, dry silica (eg, AEROSIL 130, AEROSIL 200, AEROIL manufactured by Nippon Aerosil Co., Ltd.)
SIL300, AEROSIL 380, etc.), colloidal silica (for example, Snowtex 2 manufactured by Nissan Chemical Industries, Ltd.)
0, Snow-Tex C, Snow-Tex N, Snow-Tex O, Snow-Tex S, etc.), wet silica precipitation method (for example, T-32 (S), K-4 manufactured by Tokuyama Soda Co., Ltd.)
1, F-80, etc.), wet silica gel method (for example, Syloid 244, Syloid 150, Syloid 72, Syloid 65, SHIELDEX manufactured by Fuji Devison Chemical Co., Ltd.)
Etc.) can be used. In addition, the above silica
It is also possible to use a mixture of more than one species. Such silica is stably dispersed in a water-soluble or water-dispersible base resin.

One or more of the above rust-preventive pigments are blended in the black coating composition as a component thereof. The mixing ratio of the rust preventive pigment is based on 100 parts by weight of the thermosetting resin.
The range is 1 to 100 parts by weight, preferably 3 to 60 parts by weight. When the distribution ratio of the rust-preventive pigment is less than 1 part by weight, the rust-preventive effect obtained by blending the rust-preventive pigment does not appear, while
If the amount is more than 10 parts by weight, the rust preventive pigment itself has a black effect other than black. For example, in the case of a hardly soluble yellow chromate, there is a problem that the blackness is reduced.

Further, if the solid lubricant and the particulate rust preventive pigment are added in combination, a black film excellent in both processability and corrosion resistance of the processed portion can be formed. At that time, the solid lubricant and the particulate rust preventive pigment are each 1 to 100 parts by weight, preferably 3 to 6 parts by weight, based on 100 parts by weight of the base resin.
It is added in a range of 0 parts by weight. In order to adjust the subtle color tone of black as desired, other black pigments (inorganic pigments, organic pigments) or black dyes may be added. For example,
By adding carbon black, which is a black inorganic pigment, glossiness can be adjusted and blackness can be changed. Further, by adding a coloring pigment or a coloring dye other than black, a subtle color tone such as reddish or bluish can be adjusted even in the same black.

The above black film is obtained by diluting the composition in a solvent as necessary, applying the film to a predetermined thickness by a method such as roll drawing, a roll coater or an air knife. It is obtained by heating and curing at 80 to 300 ° C (preferably 120 to 250 ° C). The coating method and the baking method are performed by a general method, and are not particularly limited. However, in the production of the steel sheet of the present invention, a coating facility for producing a highly corrosion-resistant surface-treated steel sheet possessed by a steel manufacturer is provided. There is a great merit that it can be used as it is.

[0056]

EXAMPLES Examples (1) to (6) based on the present invention and comparative examples (1) to (6) corresponding to these examples are shown below as steel sheets for home appliances and office equipment. . The plating components of each steel sheet are as follows. These are alkali-degreased, washed with water and dried, and then coated with a coating type chromate treatment solution with a roll coater or placed in an electrolytic chromate treatment bath. It was immersed to form an electrolytic chromate film, and after drying, a resin liquid was applied as a second layer by a roll coater. After further drying, it was heated and air-cooled. Ni-Zn alloy electroplating ... Ni content 12% Fe-Zn alloy electroplating ... F
e content 25%

The conditions of the coating type chromate treatment and the electrolytic chromate treatment are as follows. Coating-type chromate treatment conditions Trivalent Cr ion: hexavalent Cr ion = 2: 3, pH = 2.
5 (pH adjusted with KOH), chrome of 20g / l solid content
The coating solution was applied with a room temperature roll coater and dried. Electrolytic chromating conditions: Cathodic electrolysis with a current density of 4.9 A / dm ² and an electrolysis time of 20 seconds in a bath of 50 g / l of CrO ₃ , 0.5 g / l of H ₂ SO ₄ and a bath temperature of 50 ° C. Then, it was washed and dried.

Tables 1 to 5 show the plating original plate, the base resin for forming a black film, the black imparting agent, the solid lubricant, and the particulate rust preventive pigment used in each of the Examples and Comparative Examples. Tables 6 to 35 show test results for the plated steel sheet, the chromate film, the composition for forming a black film, and the obtained black steel sheet used in Examples and Comparative Examples. The composition for forming a black film was prepared by blending the components shown in Tables 2 to 5 in the amounts shown in Table 6 and below, and was diluted by adding a solvent as needed.

The test of the black steel sheet prepared as described above was performed as follows. (1) Blackness Suga Test Instruments Co., Ltd. multi-source spectrophotometer (model MS
Using L), the L value of the black film was measured. The evaluation criteria are as follows. ◎: L ≦ 15 ○ +: 15 <L ≦ 20 ○: 20 <L ≦ 25 ×: L> 25

(2) Weldability test The spot welding was performed under the following conditions, and the evaluation was made by the number of continuous spots. The evaluation criteria are as follows. Electrode: Cr-Cu, D type Electrode diameter: 6 mmφ Welding current: 10 kA Energizing pressure: 200 kg Energizing time: 12 cycles / 60 Hz ◎: 1000 or more points ○: 700 or more points ×: less than 700 points

(3) Corrosion resistance test of flat plate portion and processed portion A salt water spray test (JIS-Z-2371) of the flat plate portion and the Ericksen 7 mm extruded portion was performed for 480 hours. The corrosion resistance was evaluated based on the time until the amount of generated white rust reached 5% in area ratio. The evaluation criteria are as follows.

(4) Adhesion of black film 1 m on the black film surface
This was carried out by cutting 100 pieces of gobang at intervals of m and sticking and peeling an adhesive tape to this gobang. The evaluation criteria are as follows. ◎: Peeled area 0%: Peeled area less than 10% △: Peeled area 10% or more and less than 20% ×: Peeled area 20% or more

(5) Workability test 10 m with blank diameter φ120 mm and die diameter φ50 mm
Hat drawing by m-extrusion was performed, the side surface processed portion of the steel sheet was peeled off with an adhesive tape, and the degree of peeling of the film on the tape and the change in the appearance of the black film were evaluated.
The evaluation criteria are as follows.

(6) Light fastness A black film was formed according to JIS L-
0842 Fade meter irradiation by the second exposure method,
Grading was performed on a blue scale. ◎: Bull scale 7 to 8 ○: Bull scale 5 to 6 △: Bull scale 3 to 4 ×: Bull scale 1 to 2

Example (1) and Comparative Example (1) The blackness, weldability, workability, and adhesion of the material of the present invention having a black film containing different black imparting agents as shown in Tables 6 to 9 , Corrosion resistance and light fastness were examined. The results are shown in Tables 11 to 14. In this embodiment, the composition of the black film is constant at 70 parts by weight of the black imparting agent with respect to 100 parts by weight of the base resin, and the thickness of the black film is varied by changing the application conditions of the black film by a roll coater. A black film was formed. Further, the measurement and test of blackness, weldability, corrosion resistance and light fastness were also performed on each steel sheet shown in Table 10 as a comparative material. Table 15 shows the results. In FIG.
The measurement result of the blackness of Example (1) and Comparative Example (1) is shown. According to this, the agent of the present invention using a black dye as the black imparting agent has a target blackness within the range of the weldable film thickness. Further, in particular, a black steel sheet using a black azo-based metal complex dye as a black imparting agent shows excellent blackness.

Example (2) and Comparative Example (2) As shown in Tables 16 to 18, water-soluble black azo-based metal complex dyes were used as blackening agents, and different black film compositions (blackening agent concentrations) were used. The blackness, weldability, workability, adhesion, corrosion resistance and light fastness of the material of the present invention having different thicknesses were examined. The results are shown in Tables 20 to 22. In addition, blackness and weldability were measured and tested for each steel sheet as shown in Table 19 as a comparative material. Table 23 shows the results. FIG. 2 shows the measurement results of the weldability of Examples (1) and (2) and Comparative Examples (1) and (2). The weldability starts to decrease when the film thickness exceeds 2.5 μm. , Especially 3μ
If the film thickness exceeds m, proper welding becomes impossible.

Example (3) and Comparative Example (3) As shown in Table 24, as shown in FIG.
The blackness, weldability, workability, corrosion resistance and light fastness of the material of the present invention in which the type and amount of coating and the composition of the black film were changed were examined. The results are shown in Table 26.
Similar measurements and tests were also performed on each steel sheet as shown in Table 25 as a comparative material. Table 27 shows the results.

Example (4) and Comparative Example (4) The blackness, weldability, workability, and blackness of the material of the present invention having black coatings having different compositions as shown in Tables 28 and 29 were measured.
The corrosion resistance and light fastness were examined. The results are shown in Table 31 and Table 32. Similar measurements and tests were performed on each steel sheet as shown in Table 30 as a comparative material. The results are shown in Table 33.

Example (5) and Comparative Example (5) As shown in Table 34, the material of the present invention having a black film containing a black azo metal complex salt dye and a clear film containing no black azo dye were used. The corrosion resistance of the comparative material having the same was examined. Table 35 shows the results. For comparison, the same table shows No. 3 of Comparative Example (3). 3 (black film material without chromate) is also described.

As is clear from the table, the material of the present invention (Z
The n-plating base + chromate 50 mg / m ² + black film 1.5 μ) is a comparative material having a clear film (Zn plating base + chromate 50 mg / m ² + clear film)
Shows superior corrosion resistance. As described above, the material of the present invention has excellent corrosion resistance as compared with the comparative material, in addition to the barrier effect of the chromate film and the resin film, and the black azo-based metal complex salt dye incorporated in the resin has a molecular level. First, it is possible to raise the barrier effect of the resin film uniformly and densely in the black film to improve the barrier effect. Further, it is presumed that in the material of the present invention, not only the corrosion resistance due to the black film alone, but also excellent corrosion resistance is obtained by the interaction between the black film and the underlayer chromate. . It is also evident in comparison with the corrosion resistance of the black coating material without the chromat.

That is, the undercoat chrome was applied to the Zn-plated steel sheet.
The comparative material, in which only a black film was formed without forming a coating, was significantly inferior in corrosion resistance to the material of the present invention. The corrosion resistance of the material of the present invention as compared with the comparative material is not only that the barrier effect of the chromate film is simply added, but also that the black color in which the base chromate and the black azo metal complex salt dye are blended. Obviously, this is due to a synergistic effect with the coating.

Example (6) and Comparative Example (6) Coating of 50 mg / m ² of chromium was applied to the surface of a Zn-12% Ni alloy plated steel sheet whose surface was previously degreased by a continuous roll coater. And a water-soluble epoxy ester resin (Table 2 No. 2).
4) A composition comprising 70 parts by weight of an acidic black azo-based metal complex dye (Table 3 No. 5) per 100 parts by weight was continuously rolled.
The material of the present invention having a black coating having a thickness of 1.5 μm was prepared by coating with a coater and heat-setting at 140 ° C.

As a comparative material, Z whose surface was degreased was used.
An n-12% Ni alloy-plated steel sheet is immersed in a 5% by weight, 25 ° C. aqueous nitric acid solution (hereinafter referred to as a blackening treatment bath) for 5 seconds, and then washed and dried to form a black film. Was. In the comparative example, about 0.
When the 03m ² Zn-Ni plated steel sheet was blackened,
The blackness of the steel sheet gradually decreased, and the blackness L value exceeded 20 at the time of about 0.04 m ² treatment, and thereafter, the L value was sharply increased. On the other hand, in the case of the material of the present invention, continuous processing was possible as long as the prepared black film composition could be supplied.

After each test material was prepared, a part of the residue of the black coating composition solution used for forming the film of the material of the present invention was collected from a roll coater tray, and a comparative material was prepared. A part of the aqueous nitric acid solution used for the blackening treatment was collected, and the amount of zinc in each liquid was measured by an atomic absorption method (Z-8100, manufactured by Hitachi, Ltd.), and the amount of zinc eluted from the plating film was examined. As a result, although the amount of zinc was less than the trace in the solution used for forming the film of the material of the present invention, the solution used for the treatment of the comparative material showed about 5 g of Zn-12% Ni per 1 m ² of the treated area. Zinc corresponding to the elution of the plating was detected.

Next, a corrosion resistance test was performed on the above-mentioned material of the present invention and the comparative material by the same method (salt spray test) as described above. As a result, the material of the present invention did not generate any white rust even after 480 hours in the flat part, but the comparative material became entirely white rust in about 1 to 2 hours. With respect to the comparative material, after the blackening treatment, a coating type chromate film having a chromium adhesion amount of 50 mg / m ² was formed. When a clear resin film of No. 1 was formed to a thickness of 1.5 μm and the corrosion resistance test was performed again, white rust was about 5% after 240 hours of salt water spraying, and a comparison was made in which a chromate film and a resin film were not formed. Corrosion resistance was improved compared to the material. However, in the case of the black steel sheet according to the present invention, the processing step is “plated steel sheet → chromate film formation → black film formation”, whereas in the case of the above comparative material, a corrosion-resistant black steel sheet sufficient for household appliances is manufactured. For this purpose, “Zn—Ni alloy plated steel sheet → reaction type blackening treatment → (washing / drying) → chromate film formation → clear-resin film formation” is required. Since the reactive blackening step and the washing / drying step immediately after this step are not required at all, the material of the present invention is extremely advantageous also in the treatment step.

[0076]

[Table 1]

[0077]

[Table 2]

[0078]

[Table 3]

[0079]

[Table 4]

[0080]

[Table 5]

[0081]

[Table 6]

[0082]

[Table 7]

[0083]

[Table 8]

[0084]

[Table 9]

[0085]

[Table 10]

[0086]

[Table 11]

[0087]

[Table 12]

[0088]

[Table 13]

[0089]

[Table 14]

[0090]

[Table 15]

[0091]

[Table 16]

[0092]

[Table 17]

[0093]

[Table 18]

[0094]

[Table 19]

[0095]

[Table 20]

[0096]

[Table 21]

[0097]

[Table 22]

[0098]

[Table 23]

[0099]

[Table 24]

[0100]

[Table 25]

[0101]

[Table 26]

[0102]

[Table 27]

[0103]

[Table 28]

[0104]

[Table 29]

[0105]

[Table 30]

[0106]

[Table 31]

[0107]

[Table 32]

[0108]

[Table 33]

[0109]

[Table 34]

[0110]

[Table 35]

* 1: See Table 1 * 2: See Table 2 * 3: See Table 3 * 4: Indicates the parts by weight of the black agent relative to 100 parts by weight of the base resin. * 5: Refer to Table 4. * 6: Part by weight of solid lubricant with respect to 100 parts by weight of base resin. * 7: See Table 5 * 8: Indicates the parts by weight of the particulate rust preventive pigment based on 100 parts by weight of the base resin.

[0112]

According to the present invention described above, the black coating is thinner (up to 3 .mu.m) than the conventional coated steel plate, so that welding is possible and a black steel plate having excellent blackness can be obtained.
In addition to the blackness and weldability, this black steel sheet has excellent black film adhesion, workability, corrosion resistance, and light fastness, and must be manufactured by coating and baking with existing roll coater equipment. Therefore, compared with the black plate of the reactive etching type, there is no problem of bath deterioration due to elution of plating, and therefore, the productivity can be greatly improved, and black which is extremely excellent in both performance and productivity It can provide a steel plate.

[Brief description of the drawings]

FIG. 1 shows the relationship between black film thickness and blackness.

FIG. 2 shows the relationship between black film thickness and weldability.

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI B32B 27/18 B32B 27/18 E 27/20 27/20 A C23C 22/00 C23C 22/00 Z (56) References JP JP-A-63-128935 (JP, A) JP-A-61-231177 (JP, A) JP-A-60-103185 (JP, A) JP-A-2-263633 (JP, A) JP-A-2-214653 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 22/00-22/86 B05D 7/24 301 B23K 11/16 101 B32B 7/02 104 B32B 15/08 B32B 27/18 B32B 27/20

Claims (6)

(57) [Claims] 1. A chromium deposition amount (in terms of metallic chromium) of 10 to 200 mg / m ^{2 on} the surface of zinc or zinc-based alloy plating.
Having a chromate film, and on top of the chromate film,
A thermosetting resin is used as a base resin, and a black coating having a thickness of 0.3 to 3.0 μm is prepared by mixing 1 to 200 parts by weight of a black dye as a blackening agent with respect to 100 parts by weight of the base resin. Possible black steel plate. 2. The amount of chromium deposited on the surface of zinc or zinc-based alloy plating (calculated as chromium metal) 10 to 200 mg / m ^2.
Having a chromate film, and on top of the chromate film,
A thermosetting resin is used as a base resin, and a black dye of 1 to 200 parts by weight and a solid lubricant of 1 to 100 parts by weight are blended with respect to 100 parts by weight of the base resin. A weldable black steel plate having a 3.0 μm black coating. 3. The amount of chromium deposited on the surface of zinc or zinc-based alloy plating (calculated as chromium metal): 10 to ²⁰⁰ mg / m ^2.
Having a chromate film, and on top of the chromate film,
A thermosetting resin is used as a base resin, and a black dye is added in an amount of 1 to 200 parts by weight and a particulate rust preventive pigment in an amount of 1 to 100 parts by weight based on 100 parts by weight of the base resin. A weldable black steel plate having a 3-3.0 μm black coating. 4. A chromium deposition amount (in terms of metallic chromium) of 10 to 200 mg / m ^{2 on} the surface of zinc or zinc-based alloy plating.
Having a chromate film, and on top of the chromate film,
A thermosetting resin is used as a base resin, and a black dye is used in an amount of 1 to 200 parts by weight, a solid lubricant is used in an amount of 1 to 100 parts by weight, and a particulate rust preventive pigment is used in an amount of 100 parts by weight of the base resin. 0.3 to 3.0 parts by weight of 100 to 100 parts by weight
A weldable black steel plate with a black coating of μm. 5. Solid lubricants include hydrocarbon compounds such as polyolefin wax, fluororesin compounds, fatty acid amide compounds, metal soaps, metal sulfides such as molybdenum disulfide, graphite, graphite fluoride, and boron nitride. And 1 selected from the group consisting of polyalkylene glycols
The weldable black steel sheet according to claim 2 or 4, comprising at least one kind. 6. The weldable black steel sheet according to claim 3, wherein the particulate rust preventive pigment comprises one or more selected from the group consisting of a hardly soluble chromium compound and silica.