JPH04355127A - Weldable colored steel sheet - Google Patents

Abstract

PURPOSE:To provide a colored steel sheet which is within a range of a weldable film thickness, superior in a color tone and obtain a high-gloss external appearance. CONSTITUTION:This is a colored steel sheet where a chromate film is formed on a zinc plated or zinc based alloy plated surface of a steel sheet, thermosetting resin and dyes as a coloring agent are compounded with each other on the chromate film at a specific compounding ratio and a colored film comprised of a colored film composition obtained by compounding a specific additive component at need is formed at a film thickness within a specific range further.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to home appliances, office equipment,
The present invention relates to a colored steel plate that can be welded and has an excellent appearance and is suitable for copying machines and the like.

0002

[Prior Art] Recently, with the diversification and increasing quality of products in the fields of home appliances and office equipment, welding is possible by continuous and short-time treatment of zinc or zinc alloy plated steel sheets. There is an increasing need for colored steel sheets with excellent appearance, and the colors required are wide-ranging. In these fields, several black steel plates have been proposed that can be continuously produced in the form of strips and can be welded. However, with regard to weldable colored steel sheets that have an appearance mainly composed of chromatic colors other than black, it is difficult to stably produce the same color over a wide area, which has been a major technical problem.

Conventionally, there are the following methods for forming a colored film on a steel plate or a galvanized steel plate. (a) A method in which a resin film containing an organic or inorganic pigment is applied to a thickness of several tens of μm using a spray or roll coater. (b) A method of forming a colored film by reacting or electrolyzing the plating layer itself, which has already been formed as a film. (b-1) By immersing pure zinc in a chromate treatment solution containing chromic acid and acid, and changing the bath composition and reaction temperature, the surface of pure zinc plating can be painted in various colors, such as a shiny iridescent color or a matte grass green color. A method of forming a chromate film of a different color. (b-2) A method of forming a black chromate film on the surface of pure zinc plating using a chromate treatment bath containing Ag ions (JP-A-58-193376). (b-3) A method of forming a chromate film on the surface of pure zinc plating and further dyeing by immersing it in a dye solution. (b-4) A method of forming a colored film by immersion treatment in a solution containing Ni ions and Cu ions to replace and precipitate these metals on the surface of pure zinc plating. (b-5) A method of forming a black film by anodizing pure zinc plating in an alkaline bath. (b-6) A method of performing Zn-Co, Ni or Mo alloy electroplating and then anodizing to form a black film (Japanese Patent Publication No. 61-38276). (b-7) A method of obtaining a black appearance by subjecting a Zn-Ni alloy plated steel plate to immersion treatment with nitric acid or a bath containing nitric acid radicals, spray treatment, and anodization treatment (Special Publication No. 62-3
No. 0262). (c) A method of forming a colored film on the surface of a steel plate or galvanized steel plate by cathodic electrolytic treatment (for example,
(Japanese Patent Publication No. 10292/1983). (d) For the purpose of corrosion resistance and adhesion, a method in which a treatment solution prepared by adding an organic dye to a potash water glass solution is applied to zinc or galvanized surfaces (Japanese Patent Publication No. 55-30593
issue).

0004

[Problems to be Solved by the Invention] However, these conventional techniques have the following problems. First, (a
) is a general coating method, and in this method, organic pigments or inorganic pigments (hereinafter collectively referred to as colored pigments) are used as colorants. However, with this type of steel sheet, it is necessary to uniformly disperse the coloring pigment in the coating film in order to obtain a stable and even color tone, so a film thickness of about 10 μm is generally required, and therefore spot welding is required. is impossible. That is, with conventional colored pigments, it has been impossible to ensure a stable color tone with a film thickness within the weldable range (3 μm or less).

[0005] Among the methods (b), (b-2), (
b-5), (b-6), and (b-7) are techniques that are limited to black, and each of the various methods in (b) has the following problems. First, the method (b-1) has a problem in that the color varies depending on the slight difference in the thickness of the chromate film, which tends to cause unevenness in appearance. Further, the colors obtained are limited to yellow to green colors peculiar to reactive chromates, and it is impossible to obtain any color tone. The method (b-2) has the problem that, as described above, the color is limited to black, and the processing liquid contains Ag ions, so the cost is extremely high. (b-3
The method (2) has a problem that it cannot be applied to short-time processing (within 5 seconds) which is based on continuous production using strips because the processing time for dyeing the chromate film is long, several minutes or more. In method (b-4), the processing time is long, several minutes or more, and the resulting film has poor adhesion.
There is also the problem that the film formed by substitutional precipitation with Cu ions oxidizes and discolors over time. The method (b-5) is also not suitable for continuous treatment using strips because the treatment time is as long as 5 to 20 minutes.

[0006] Methods (b-6) and (b-7) allow short-time processing, but as mentioned above, the color is limited to black. Moreover, since both of these methods involve eluting a portion of the plating formed in advance during the blackening treatment, they are not only uneconomical, but also metal ions eluted from the plating deteriorate the blackening treatment. This becomes a major problem in continuous operation. In addition, method (b-6) uses Zn-C
There is also the problem that the types of underlying metals are limited, such as the method (b-7) is limited to Zn--Ni alloy plating, and the method (b-7) is limited to Zn--Ni alloy plating. Also,(
Method c) mainly uses a black film, and
There is a problem that the adhesion of the film is poor.

Next, method (d) is not intended to provide a coating with an excellent appearance, and the thickness of the coating is not specified, so it is not intended to provide weldability. do not have. Furthermore, since potash water glass is used as the basic material of the coating, the coating after hardening does not have sufficient lubricity during press processing, making it unsuitable for use on steel plates intended for home appliances, office equipment, etc.

The present invention has been made to solve the above-mentioned problems.
In order to provide spot weldability that was not possible with method (a) above, we sought to provide a colored steel sheet that has an excellent color tone and a high-gloss appearance within the range of weldable film thickness. Make it the first purpose. By solving the problems of the above method (a), the problems of the conventional reaction or electrolytic method (the above method (b)) do not occur. In other words, various colors can be freely selected and a uniform color tone can be obtained. Another object of the present invention is not only to be weldable and have an excellent appearance, but also to have corrosion resistance and
The objective is to provide a colored steel sheet with excellent adhesion and workability.

[0009]

[Means for Solving the Problems] The present inventors have achieved the above-mentioned object, in particular, to obtain a colored film (colored film of a color other than black) with a uniform and beautiful color tone within the range of weldable film thickness. For this purpose, we conducted a thorough study. As a result, the above objective can be achieved by forming a colored film made of a composition containing a base resin and a colored dye in a predetermined ratio with a film thickness within a specific range, and A colored steel sheet with even better corrosion resistance, adhesion, and workability can be obtained by forming the upper film into a specific multilayer structure including the above-mentioned colored film, and by adding specific components to the colored film composition as needed. The present invention has been completed by discovering that

[0010] According to the present invention, a chromate film is formed on the galvanized or zinc-based alloy plated surface of a steel sheet, and a thermosetting resin and a dye are mixed in a specific range on the chromate film. The gist of this method is to form a colored film with a thickness within a specific range from a colored film composition that has been blended with specific additive components as needed. That is, the present invention has the following configuration.

(1) Amount of chromium deposited on the surface of zinc or zinc-based alloy plating (metallic chromium equivalent) of 10 to 200 mg/
m2 of chromate film, a thermosetting resin is used as a base resin on the top of the chromate film, and this base resin 100
A weldable colored steel sheet having a colored film (excluding a black film) having a thickness of 0.3 to 3.0 μm and containing 1 to 200 parts by weight of a dye as a coloring agent.

(2) Amount of chromium deposited on the surface of zinc or zinc alloy plating (metallic chromium equivalent) 10 to 200 mg/
m2 of chromate film, a thermosetting resin is used as a base resin on the top of the chromate film, and this base resin 100
A film with a thickness of 0 containing 1 to 200 parts by weight of a dye as a coloring agent and 1 to 100 parts by weight of a solid lubricant based on the weight part.
．． 3-3.0 μm colored film (excluding black film)
Weldable colored steel plate with.

(3) Amount of chromium deposited on the surface of zinc or zinc alloy plating (metallic chromium equivalent) 10 to 200 mg/
m2 of chromate film, a thermosetting resin is used as a base resin on the top of the chromate film, and this base resin 100
A colored film with a thickness of 0.3 to 3.0 μm containing 1 to 200 parts by weight of a dye as a coloring agent and 1 to 100 parts by weight of a particulate rust-preventing pigment based on the weight part (excluding a black film) ) Weldable colored steel plate.

(4) Amount of chromium deposited on the surface of zinc or zinc-based alloy plating (metallic chromium equivalent) 10 to 200 mg/
m2 of chromate film, a thermosetting resin is used as a base resin on the top of the chromate film, and this base resin 100
A film having a thickness of 0.3 to 3.0 μm, containing 1 to 200 parts by weight of a dye as a coloring agent, 1 to 100 parts by weight of a solid lubricant, and 1 to 100 parts by weight of a particulate rust-preventing pigment.
A weldable colored steel sheet having a colored film (excluding a black film).

(5) In the colored steel sheet described in (2) or (4) above, the solid lubricant may be a hydrocarbon compound such as a polyolefin wax, a fluororesin compound, a fatty acid amide compound, a metallic soap, or 1 selected from the group of metal sulfides such as molybdenum sulfide, graphite, graphite fluoride, boron nitride, and polyalkylene glycol.
Weldable colored steel plate containing one or more species.

(6) In the colored steel sheet described in (3), (4) or (5) above, as the particulate rust preventive pigment, one selected from the group consisting of a sparingly soluble chromium compound and silica.
Weldable colored steel plate containing one or more species.

[0017]

[Operation] The details of the present invention and the reasons for its limitations will be explained below. The present invention provides a black coating (substantially black dye as a coloring agent).
This applies to colored steel sheets other than so-called black steel sheets that have a black film containing only a black imparting agent such as black pigment, and therefore, the colored steel sheets and colored films described below do not include black steel sheets and black films. do not have. Here, in the present invention, in order to distinguish it from a black steel sheet, a colored steel sheet is defined as having a chromatic or achromatic colored film with a lightness L value of over 25. However, as will be described later, this does not preclude the addition of black dye to the film by mixing it with dyes of other colors. In addition, most colored steel sheets are generally chromatic, but
As described above, the present invention does not exclude colored steel sheets in achromatic colors other than black.

The colored steel sheet of the present invention is made from a composition that uses a zinc-plated or zinc alloy-plated steel sheet as a starting material, has a chromate film on its surface, and furthermore has a thermosetting resin base and a dye blended thereon. It has a colored film. FIG. 1 schematically shows the cross-sectional structure of the colored steel sheet of the present invention.

[0019] As the starting material, zinc-based plated steel sheet,
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, Cr, etc. are added to the plating components of zinc-aluminum alloy plated steel sheets, zinc-cobalt-chromium alloy plated steel sheets, and any of these steel sheets. Those added can be used. Further, a steel sheet having dispersion plating in which particulate resin, silica, a chromium compound, etc. are eutectoided in any of the above-mentioned platings can be used. Furthermore, it may be a composite plated steel sheet having two or more layers of the same or different types of plating as described above. For example, F with different Fe contents
A plating film having two or more layers of e-Zn alloy plating can be used as the base.

[0020] If only the appearance is desired, it is possible to use hot-rolled steel sheets or cold-rolled steel sheets without a plating film as the starting material, and for the same reason, stainless steel sheets, aluminum alloy sheets, A material such as a titanium alloy plate can also be used. However, considering the use of forming and unpainted colored steel sheets for home appliances, it is desirable to use the above-mentioned zinc-based plated steel sheets as the starting material in terms of performance such as cost and corrosion resistance. A galvanized steel sheet was specified as the starting material. As the method for plating these zinc-based plated steel sheets, any practicable method among electrolytic methods, melting methods, vapor phase methods, etc. can be adopted.

A chromate film is formed on the surface of the above plated steel sheet by chromate treatment. In the colored steel sheet of the present invention, extremely excellent corrosion resistance can be obtained by the combination of this chromate film and a colored film containing a specific coloring agent (dye) as described below.

This chromate film has a chromium deposition amount (d
ry) from 10 to 200 mg/m2, preferably 30
~80mg/m2 (more than that in terms of metal chromium). When the amount of chromium deposited exceeds 200 mg/m2, workability and weldability tend to deteriorate. In addition, the amount of chromium deposited is 10m
If it is less than g/m2, the coating may become non-uniform and the corrosion resistance may deteriorate. In addition, the chromate film has hexavalent Cr.
It is preferable that there exist. Hexavalent Cr ions have a repair effect, and when a steel plate is damaged, it acts to suppress corrosion from there.

[0023] The chromate treatment for such a base film may be performed by any known method such as a reaction type, a coating type, or an electrolytic type. However, if the color of the colored film on the upper layer is bright yellow, red, blue, etc., the color tone of the colored film will be affected by the color of the chromate film on the lower layer, resulting in a dull color. To avoid this, it is preferable that the color of the chromate film be close to white.

The coating type chromate treatment liquid has a partially reduced chromic acid solution as its main component, and if necessary, it contains a water-dispersible or water-soluble organic resin such as an acrylic resin and/or a water-soluble acrylic resin.
Alternatively, it contains silica (colloidal silica, fumed silica) with a particle size of several microns to several hundred microns. In this case, the ratio of trivalent Cr ions/hexavalent Cr ions is 1/1 to
1/3, pH is 1.5-4.0 (more preferably 2-3
) is 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. Further, as the coating type chromate treatment, any method such as a roll coater method, a dipping method, a spray method, etc. may be used. In coating type chromate treatment, a film is obtained by drying without washing with water after the chromate treatment. The reason for drying without washing with water is that normal washing with water removes hexavalent Cr ions, and the ratio of trivalent Cr ions/hexavalent Cr ions is maintained stably as it is, and the upper part The formed resin film suppresses excessive outflow of hexavalent Cr ions in a corrosive environment, effectively maintains the passivation effect over a long period of time, and provides high corrosion resistance.

On the other hand, in electrolytic chromate treatment, 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 oxygen acid, followed by water washing and drying. to form a film.

Comparing the chromate films produced by the above two treatment methods, the coating type chromate has superior corrosion resistance as it contains more hexavalent chromium than the electrolytic chromate. When heat treated to do so, the film becomes dense and strong, resulting in better corrosion resistance than electrolytic chromate. On the other hand, electrolytic chromate has the advantage that the film has a high degree of completion regardless of the presence or absence of heat treatment, and also has the advantage that the amount of film deposited can be easily controlled.

Next, the components of the colored film will be explained. The colored film according to the present invention is characterized in that it uses a thermosetting resin as a base resin and contains a dye as a coloring agent. Furthermore, 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 colored film, and a rust preventive pigment can be contained for the purpose of improving the corrosion resistance.

The function required as a coloring agent is that it can exhibit a uniform and beautiful color in a weldable film (3 μm or less). Moreover,
When the coloring agent is mixed with the base resin at a mixing ratio that provides a sufficient appearance, there is no possibility that it will have a negative effect on other properties required for the colored film, such as processability and corrosion resistance. It won't happen.

Colorants can be broadly classified into pigments (inorganic pigments and organic pigments) and dyes. Pigments are generally particulate and dispersed in a solvent. These are widely used for coating automobiles and home appliances, and include inorganic pigments such as navy blue and yellow lead, and organic pigments such as xacridone pigments and phthalomianine pigments. These ordinary coatings generally have a film thickness of 10 μm.
It cannot be welded because it is thick (more than 300 ft).

[0030] The weldable thin film (
If such a pigment is used at a thickness of 3 μm or less, the pigments will come into contact with each other and coagulate in the thin film, resulting in problems such as insufficient hiding power and lack of luster in the film. In addition, especially when a large amount of pigment is added to a resin film, the workability and adhesion of the film decrease, and furthermore, water tends to penetrate into the base through the gaps between the pigment particles, resulting in a decrease in corrosion resistance. There are also problems. When a pigment is used as a coloring agent in such a thin film, a good appearance cannot be obtained;
Further, there is a problem that, especially when added in a large amount, the performance of the film is impaired. Therefore, conventionally it has been impossible to obtain a weldable thin colored film with a good appearance. In addition, two inorganic pigments and organic pigments such as those mentioned above can be used.
Even if more than one type is combined, sufficient performance cannot be obtained.

In contrast, the present inventors have found that dyes can form colored films with good appearance even if they are thin. Inorganic pigments and organic pigments are particles, and in a thin film, they tend to aggregate or create gaps between particles, resulting in extremely low gloss or uneven color density in the film. On the other hand, since dyes are soluble in water or organic solvents, it is possible to uniformly and densely disperse very fine particles at the molecular level in the film, making it possible to create an excellent colored film even in a thin film. It is thought that it can be formed.

[0032] Next, it is said that there are several thousand types of dyes currently on the market under trade names, but these can be roughly divided into two types of classification methods: chemical structural classification method (1) They are classified according to the practical classification method (2) based on dye characteristics (for example, "Organic Chemistry Handbook" published by Gihodo, edited by the Synthetic Organic Chemistry Association). In the classification method based on chemical structure (1), dyes are classified according to the main structure that causes coloration within the dye molecule, and include nitroso dyes, nitro dyes, azo dyes (monoazo dyes, disazo dyes, trisazo dyes, tetrakisazo dyes), and anthraquinone dyes. , indigo dyes, azine dyes, cyanine dyes, phthalocyanine dyes, stilbene dyes, sulfur dyes, triazole dyes, triphenylmethane dyes, acridine dyes, diphenylmethane dyes, oxazine dyes, and the like.

On the other hand, a practical classification method based on dye characteristics (2
), direct dyes, acid dyes, basic dyes, acid mordant dyes, metal complex dyes, sulfur dyes, vat dyes, Izog dyes, disperse dyes, reactive dyes, oxidation dyes, fluorescent whitening dyes, oil-soluble ( (organic solvent soluble) dyes, etc.

According to the above classification, for example, dyes classified as acidic dyes according to the classification method (2) are further classified as (
According to the classification method 1), they can be classified into azo dyes (monoazo, disazo, trisazo, tetrakisazo), anthraquinone dyes, triphenylmethane dyes, azine dyes, etc.

On the other hand, color, which is an important characteristic of dyes, is due to the combination of groups (chromophores) with unsaturated bonds such as -CH=CH- and -N=N- in their chemical structure, and -NH2, - This is because light of a certain wavelength is absorbed by a group with a free electron pair (auxochrome) such as OH, and the unabsorbed wavelength of light is captured by the naked eye as the color of the object. , there will be dyes of various colors. In "COLOUR INDEX" described below, these colors are classified into yellow, orange, red, violet, blue, green, brown, and black.

By the way, “THE SOCIETY O
F DYERS AND COLOURISTS” and “
AMERICAN ASSOCIATION OF T
EXTILE CHEMISTS AND COLOU
``COLOUR INDEX (T
HIRD EDITION Vol. 1 to 8)" describes the classification, structure, properties, uses, etc. to which commercially available dyes belong, and each dye is classified under this "COLOUR IND".
"C.I.Generi" classified and defined in "EX"
c Name". In other words, this "COLOUR INDEX" classification method first divides commercially available dyes into practical categories that are almost the same as the classification in (2) above, then displays the color categories, and then, among them, Classified by dyes with the same chemical structure (numbered sequentially starting from 1). If the specific structural formula is clear, the structure is expressed by "C.
I. "Constitution Number" is written on it, but even if it is not, most of the items have the above-mentioned (
For example, chemical structural classifications such as azo (monoazo, disazo, etc.), anthraquinone, azine, etc., such as the classification 1) are described.

For example, yellow dyes in the acid dye category are displayed in the category "C.I.Acid Yellow", and among them, "C.I.Acid Yellow"
"Yellow 1" is a monoazo dye with a specific chemical structure, "C.I. Acid Yellow 28" is a disazo dye with a specific chemical structure, "C.I.Ac
id Yellow 109" is classified as atraquinone dye with a specific chemical structure, and the color, characteristics, uses, etc. are described for each. This "C.I. Generic Name" can be compared with the trade name of a commercially available dye.

The following functions are required as a coloring agent in a colored film. (1) It must be able to be dissolved or dispersed in the base resin (thermosetting resin) and solvent (regardless of whether it is water-based or organic solvent-based), and it must not change color during thermosetting by baking (2)
The formed colored film has a weldable thin thickness (~3
(3) The color should not deteriorate even when used on steel plates for home appliances, office equipment, etc. that are illuminated by various light sources. In other words, as a result of studies to ensure good light fastness, by blending the above-mentioned dye with a thermosetting resin, a clear and uniform appearance can be obtained even in weldable thin films (3 μm or less). It has been found.

However, it goes without saying that dyes that are not registered in the "COLOUR INDEX", such as newly developed dyes that have not yet been registered, or a mixture of a plurality of dyes can be used. Further, the mixture may be a mixture of dyes of the same color or a mixture of dyes of different colors. For example, it is generally known that when a yellow dye and a red dye are mixed, an orange color is obtained due to the law of subtractive color mixture, but it is also possible to obtain films of various colors using this principle. It is.

Examples of dyes include azo dyes, azo-methine dyes, quinoline dyes, ketone imine dyes, fluorone dyes, nitro dyes, xanthene dyes, acenaphthene dyes, quinophthalone dyes, anthraquinone dyes, aminoketone dyes, methine dyes, perylene dyes, and coumarin dyes. , perinone dyes, triphenyl dyes, triallylmethane dyes, phthalocyanine dyes, inclophenol dyes, azine dyes, etc., and one or a mixture of two or more of these dyes may be used.

[0041] Further, in the above study, the present inventors found that
Among the above dyes, by adding an azo metal complex dye, which is one of the azo dyes, the most excellent appearance,
It has been found that a colored film having light fastness and corrosion resistance can be obtained. The azo metal complex dye referred to in the present invention is
It belongs to the eight color classifications mentioned above in "COLOUR INDEX" and is a complex compound of an azo dye and a trivalent metal such as chromium, copper, or cobalt.

The characteristics of this dye are: 1. It can produce a bright and uniform color tone even in a thin film; 2. It is a complex compound of 2 molecules of azo dye and 1 atom of metal (2:1 type metal complex salt) or azo dye. Due to its structure, which is thought to be a complex compound with one metal atom per molecule (1:1 type metal complex salt), it has better stability against light (light fastness) than other dyes. . Metals that can form complex salts with dyes include Cr, Co, Cu, Fe, Al, etc., but many of them mainly form complex salts with Cr.

[0043] As mentioned above, this azo metal complex dye belongs to eight types of color classifications in the "COLOUR INDEX", and each classification includes the following, for example. 1) "C.I. Acid Yellow": 59, 10
0, 133, 139, 185, 407 2) "C.I. Acid Orange": 60, 96
, 107, 129, 139 3) "C.I. Acid Red": 186, 190,
209, 281, 339 4) "C.I. Acid Violet": 58, 98
, 1115) "C.I. Acid Blue": 152
, 179, 200, 240, 268 6) "C.I. Acid Green": 35, 49,
52, 60, 92 7) "C.I. Acid Brown": 231, 25
5, 270, 299, 328 8) "C.I. Acid Black": 8, 107,
108, 120, 155

[0044] Also, as mentioned above, "COLOUR I
Azo metal complex dyes that are not registered in NDEX, such as those that have been newly developed and have not yet been registered, or mixtures of multiple types of dyes, in which at least one type of azo metal complex dye is included in the mixture. It goes without saying that you can use anything that includes .

[0045] When such an azo metal complex dye is blended as a coloring agent in a colored film, even a thin film (~3 μm) within the weldable range shows a uniform and excellent appearance;
Furthermore, since the dye itself has excellent light fastness, there is no problem at all when using colored steel sheets for home appliances, office equipment, etc. that are illuminated by various light sources.

A colored film to which an azo metal complex dye is added has excellent corrosion resistance as described above, and its corrosion resistance is far superior to a colored film containing a pigment as a coloring agent. This is because the azo metal complex dye is uniformly and densely distributed within the colored film at the molecular level, and when using an azo metal complex dye in which the metal that forms the complex salt as a water-soluble dye is Cr. Possible factors include that trivalent Cr ions forming the complex salt of this dye form an oxide that becomes a passive film. Steel sheets with such a colored film have a barrier effect due to the formation of a passive film of the base chromate (action of trivalent Cr ions) and a barrier effect of the resin film itself, as well as an anticorrosive effect due to the above-mentioned azo metal. The barrier effect of the complex salt dye increases corrosion resistance, and the hexavalent Cr of the base chromate
A high degree of corrosion resistance can be obtained due to factors such as a self-healing action that repairs defects in the passive film by ions → trivalent Cr ions, and good adhesion between the base Zn plating, the chromate film, and the colored film.

Furthermore, as shown in Example (6) below, by using an azo chromium complex dye as the azo metal complex dye, a synergistic effect between the trivalent Cr ions and the underlying chromate can be achieved. Estimated extremely excellent corrosion resistance is obtained. For the reasons mentioned above, the most preferable azo metal complex dye is one in which the metal forming the complex salt is trivalent Cr ion (azo chromium complex dye).

Since the dye is easily dissolved in a solvent, it is possible to prepare a composition for a colored film by mixing it with a thermosetting resin. When incorporated as a coloring agent in a colored film in this manner, even a thin film (up to 3 μm) within the weldable range exhibits a uniform and excellent appearance. In addition, unlike conventional coloring treatments that involve reactions such as etching, electrolytic treatment, and displacement plating, the biggest advantage of coating treatment is that there is no bath deterioration associated with the treatment, and there are no restrictions on the type of underlying plating. You can also make use of it.

Next, in the colored film of the steel sheet of the present invention, the mixing ratio of the dye to the thermosetting resin, the range of the film thickness, and the reason for the limitation will be explained. Dye is thermosetting resin 1
1 to 200 parts by weight, preferably 5 to 200 parts by weight
Add 120 parts by weight. In addition, the thickness of the colored film is 0.3
~3.0 μm, preferably 0.7 to 2.5 μm.

First, the upper limit of the amount of dye blended is 200 parts by weight, preferably 120 parts by weight per 100 parts by weight of the thermosetting resin.
The reason why it is expressed as parts by weight is because if the blending amount exceeds this upper limit, especially 200 parts by weight, the dye will not dissolve in the resin or solvent.
Not only is it uneconomical because the dye precipitates or becomes coarse particles, but if an insoluble dye is mixed into the film, it will have a negative effect on the color tone, and furthermore, the colored film may peel off at the bending part. This is because it becomes significant. In addition, the lower limit of the amount of dye blended is 1 part by weight, preferably 5 parts by weight, per 100 parts by weight of the thermosetting resin.
This is because the coloring effect is particularly low when the amount is less than 1 part by weight.

Next, the reason why the upper limit of the film thickness is set to 3.0 μm, preferably 2.5 μm is that the film thickness is set to 3.0 μm, preferably 2.5 μm.
This is because if it exceeds 0 μm, spot weldability will be significantly reduced. In addition, the lower limit of the film thickness is 0.3 μm, preferably 0.
．． The reason for setting it to 5 μm is that the film thickness is at this lower limit, especially 0.3 μm.
This is because if it is less than m, the hiding power will be insufficient, and the base will be visible and the color tone will be uneven. Figure 2
This is a summary of the prescribed range of the present invention as described above.

The base resin of the colored film of the steel sheet of the present invention is a thermosetting resin. The reason why such a resin is specified as the base resin is that when a thermoplastic resin is used, a problem arises in the scratch resistance of the formed colored film.

Examples of thermosetting resins include acrylic copolymer resins, alkyd resins, epoxy resins, polybutadiene resins, phenol resins, polyurethane resins, fluororesins, mixtures of two or more of these resins, and other monomers. Examples include addition condensates with and modified derivatives with other resins. Among these, acrylic copolymer resins, alkyd resins, epoxy resins, fluororesins, and the like are preferred.

The above-mentioned acrylic copolymers are resins synthesized by solution polymerization, emulsion polymerization, suspension polymerization, etc. using ordinary unsaturated ethylenic monomers, and include methacrylate, acrylic, etc. Hard monomers such as nitrile, styrene, acrylic acid, acrylamide, and vinyltoluene are essential components, and unsaturated vinyl monomers are appropriately blended with this for the purpose of imparting hardness, flexibility, and crosslinking properties to the resin. obtained by Further, this resin can also be modified with other alkyd resins, epoxy resins, phenol resins, etc.

[0055] As the alkyd resin, known ones obtained by ordinary synthesis methods can be used, such as oil-modified alkyd resin, rosin-modified alkyd resin, phenol-modified alkyd resin, styrenated alkyd resin,
Examples include silicone-modified alkyd resin, acrylic-modified alkyd resin, and oil-free alkyd resin (polyester resin).

Epoxy resins include straight epoxy resins such as epichlorohydrin type and glycidyl ether type, and fatty acid modified epoxy resins (epoxy ester resins).
, 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, etc. are used. Known predetermined curing agents are used for these resins. Examples of the curing agent include melamine, blocked isocyanate, and urea.

The colored film of the steel sheet of the present invention described above has the necessary properties as it is, but even better properties can be obtained by adding the additives described below.

First, in order to impart good self-lubricating properties to the colored coating, it is desirable to add a solid lubricant to the coating composition. Examples of solid lubricants applicable to the present invention include the following.・Hydrocarbon lubricants; for example, natural paraffin, synthetic paraffin, microwax, polyethylene wax, chlorinated hydrocarbons, etc. ・Fluororesins; for example, polyfluoroethylene resin, polyvinyl fluoride resin, polytetrafluoroethylene resin, Polyvinylidene fluoride resin etc./fatty acid amide lubricant; for example, stearic acid amide,
Palmitic acid amide, methylene bis stearamide, ethylene bis stearamide, oleic acid amide, ethyl acid amide, alkylene bis fatty acid amide, etc. Metallic soaps; for example, calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc.・Metal sulfides: molybdenum disulfide, tungsten disulfide ・Others: graphite, graphite fluoride, boron nitride, grease, alkali metal sulfates, etc.

However, the solid lubricant is preferably one that does not affect the color of the colored film when added. For example, achromatic hydrocarbon lubricants, fluororesins, etc. can be applied to colored films of any color, but consideration must be given to applying black molybdenum disulfide only to dark colored films. It is.

The solid lubricant is blended in an amount of 1 to 100 parts by weight, preferably 3 to 60 parts by weight, per 100 parts by weight of the thermosulfurizing resin. The blending amount is less than 3 parts by weight, especially 1
If the amount is less than 60 parts by weight, the effect of improving the lubrication of the colored film by adding the solid lubricant will be poor; on the other hand, if it exceeds 60 parts by weight, especially 10
If it exceeds 0 parts by weight, the strength of the colored film after curing will decrease and a portion of the film will adhere to the press mold, which is not suitable.

The colored film obtained by applying a colored film composition consisting of a base resin and a 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 the processed parts, it is possible to add a particulate anti-corrosion pigment to the colored coating composition, which is preferable because even better corrosion resistance can be obtained and the applications of the colored steel sheet can be expanded. As the particulate antirust pigment, one or more selected from sparingly soluble chromate and silica are used.

Examples of sparingly soluble chromates include barium chromate (BaCrO4) and strontium chromate (Sr
CrO4), lead chromate (PbCrO4), zinc chromate (ZnCrO4.4Zn(OH)2), calcium chromate (CaCrO4), potassium zinc chromate (K2
O・4ZnO・4CrO3・3H2O), silver chromate (
AgCrO4).

When using organic solvent-soluble resin as the base resin, hydrophobic silica is effective from the viewpoint of compatibility with the organic solvent (ease of compatibility), and colloidal silica made hydrophobic, Examples include hydrophobicized fumed silica. Specifically, organic solvent-dispersed colloids dispersed in solvents such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, ethyl cellosolve, and nethylene glycol. Silica (for example, manufactured by Catalysts & Chemicals Co., Ltd.)
OSCAL 1132, 1232, 1332, 14
32, 1532, 1622, 1722, 1724, etc.),
■ Silica whose surface has been made hydrophobic with an organic solvent or a reactive silane compound, i.e. hydrophobic ultrafine particle silica (e.g.
Made by Nippon Aerosil Co., Ltd. R974, R811, R8
12, R805, T805, R202, RY200, R
X200, etc.). The above hydrophobic silica is
Stably disperses in organic solvent-soluble base resin.

When a water-soluble or water-dispersible resin is used as the base resin, dry silica (for example, AEROSIL 130, AEROSIL manufactured by Nippon Aerosil Co., Ltd.)
L 200, AEROSIL300, AEROSIL
380, etc.), colloidal silica (for example, Snowtex 20, Snowtex C, Snowtex N, Snowtex O, Snowtex S manufactured by Nissan Chemical Industries, Ltd.)
etc.), wet silica precipitation method (e.g. T-32(S), K-41, F-80 manufactured by Tokuyama Soda Co., Ltd.), wet silica gel method (e.g. Thyroid method manufactured by Fuji Davison Chemical Co., Ltd.) 244, Thyroid 150, Thyroid 72, Thyroid 65, SHIELDEX, etc.) can be used. It is also possible to use a mixture of one or more of the above silicas. The silica described above is stably dispersed in a water-soluble or water-dispersible base resin.

[0065] However, it is preferable that the addition of the rust-preventing pigment has a small effect on the color of the colored film. For example, it is not preferable to add a yellow, slightly soluble chromate to a film of other colors such as red or blue.

[0066] One or more of the above rust-preventing pigments are blended into the above-mentioned colored film composition as its constituent components. The amount of anti-corrosion pigment is 1 part by weight per 100 parts by weight of thermosetting resin.
~100 parts by weight, preferably 3 to 60 parts by weight. If the amount of the rust-preventive pigment is less than the above-mentioned lower limit, especially 1 part by weight, the rust-preventive effect due to the addition of the rust-preventive pigment will not be obtained. Excessive amount of rust pigment not only reduces the lubricity of the colored film, but also causes problems such as reduced surface gloss and marked change in color.

[0067] Furthermore, by adding the solid lubricant and the particulate rust preventive pigment in combination, it becomes possible to form a colored film that is excellent in both workability and corrosion resistance of the processed parts. At that time, the solid lubricant and the particulate antirust pigment are each 1 to 100 parts by weight, preferably 3 to 6 parts by weight, relative to 100 parts by weight of the base resin.
It is added in an amount of 0 parts by weight. In addition, in order to adjust the color tone and gloss of the colored film according to your preference, other colored pigments (
Inorganic pigments, organic pigments) and colored dyes may also be added. For example, by adding an inorganic pigment or an organic pigment, it is possible to improve the hiding power and make the color deeper, or to adjust the gloss level. Further, as described above, by mixing dyes of different colors or dyes with different chemical structures, a colored film with a new color can be formed.

[0068] The above colored film is prepared by diluting the composition with a solvent as necessary and applying it to a predetermined thickness using a method such as roll squeezing, roll coater, or air knife, and then heating the plate to a temperature of 80 to 300°C (preferably). is obtained by heating and curing at 120 to 250°C). The coating method and baking method are carried out using general methods, and there are no particular restrictions. However, in the production of the steel sheet of the present invention, a major advantage is that the coating equipment owned by steel manufacturers for manufacturing highly corrosion-resistant surface-treated steel sheets can be used as is. There are benefits.

[0069]

[Examples] Examples (1) to (7) based on the present invention and comparative examples (1) to (7) corresponding to these examples are shown below as steel plates for home appliances and office equipment. The plating components of each steel plate are as follows, and after degreasing with alkaline, it is washed with water and dried, and then a coated chromate treatment solution is applied with a roll coater or immersed in an electrolytic chromate treatment bath to form an electrolytic chromate film. After drying, a resin liquid was applied as a second layer using a roll coater. After further drying, it was heat-treated and air-cooled. Ni-Zn alloy electroplating...Ni content: 12%Fe-
Zn alloy electroplating...Fe content: 25%

[0070]
The conditions for the above coating type chromate treatment and 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), a chromate treatment solution with a solid content of 20 g/l was applied at room temperature using a roll coater and then dried. - Electrolytic chromate treatment conditions CrO3: 50 g/l, H2SO4: 0.5 g/l, bath temperature 50°C, current density 4.9 A/dm2, electrolysis time 20 seconds, cathodic electrolysis treatment, washing with water, drying.

Tables 1 to 4 show the base resin for forming a colored film, coloring agent, solid lubricant, and particulate antirust pigment used in each example and comparative example.
~Table 26 shows the test results for the plated steel sheets, chromate films, compositions for forming colored films, and the obtained colored steel sheets used in the present examples and comparative examples. The composition for forming a colored film was prepared by blending the components shown in Tables 1 to 4 in the amounts shown in Table 5 and below, and diluted by adding a solvent as necessary. Further, tests on the colored steel sheets prepared above were conducted as follows.

(1) Appearance evaluation The appearance of the obtained colored film, particularly the unevenness of color tone, was visually evaluated. The evaluation criteria are as follows. ◎: Uniform and beautiful appearance ○: Almost uniform and beautiful △ to ×: Surface is rough and lacks luster. Or, the color tone becomes uneven and is not beautiful.

(2) Glossiness Using a glossmeter manufactured by Suga Test Instruments Co., Ltd., the glossiness was measured at an incident angle and a reflection angle of 60°. The higher the glossiness value, the higher the glossiness.

(3) Weldability test Spot welding was performed under the following conditions and evaluated by the number of consecutive welds. Electrode: Cr-Cu, D-type electrode diameter
: 6mmφ Welding current: 10kA Current application force: 200kg Current application time: 12 cycles/60Hz The evaluation criteria are as follows. ◎: 1000 RBIs or more ○: 700 RBIs or more ×: Less than 700 RBIs

(4) Corrosion resistance test of flat plate part and processed part Salt spray test (JI
S-Z-2371) was carried out for 480 hours. Corrosion resistance evaluation is based on the area ratio of 5 for the amount of white rust on flat plate parts.
%, and for processed areas, the evaluation was based on the time it took for white rust to start flowing downward from the processed areas. The evaluation criteria are as follows. ◎: No white rust + ○: Over 240 hours, within 480 hours ○: Over 120 hours, within 240 hours - ○: Over 72 hours, within 120 hours △: Over 24 hours, within 72 hours ×: Within 24 hours

(5) Adhesion of the colored film 100 gobbins are carved at 1 mm intervals on the colored film surface.
This was done by attaching and peeling adhesive tape to the grids. The evaluation criteria are as follows. ◎: Peeling area 0% ○: Peeling area less than 10% △: Peeling area 10% or more, less than 20% ×: Peeling area 20% or more

(6) Press formability test 10m with blank diameter φ120mm and die diameter φ50mm
A hat drawing process was performed using m-extrusion, and the processed side surface of the steel plate was peeled off with an adhesive tape, and the degree of peeling of the film to the tape and the change in the appearance of the colored film were evaluated. The evaluation criteria are as follows. ◎: No powdery peeling at all. +○: Some powdery peeling occurs locally, but the appearance of the colored film remains almost unchanged. ○: The tape is extremely lightly colored due to powdery peeling, but the appearance of the colored film remains almost unchanged. -○: The tape is lightly colored due to powdery peeling, and the appearance of the colored film becomes slightly white. Δ: The tape was colored due to powdery peeling, and the colored film was noticeably whitened. ×: The tape is significantly colored due to powdery peeling, and the colored film is completely peeled off.

(7) Lightfastness The colored film was irradiated with a fade meter using the JIS L-0842 second exposure method, and graded using a blue scale. The evaluation criteria are as follows. ◎: Blue scale grade 7-8 ○: Blue scale grade 5-6 △: Blue scale grade 3-4 ×: Blue scale grade 1-2

Example (1) and Comparative Example (1) Appearance, gloss, weldability, processability, adhesion, corrosion resistance, and light fastness were evaluated for the materials of the present invention having colored films containing different coloring agents. Examined. Similar measurements and tests were also conducted on comparative materials. The results are shown in Tables 5 and 6. In this example, the composition of the colored film was constant at 70 parts by weight of the coloring agent relative to 100 parts by weight of the base resin, and the film thickness was also constant at 1.5 μm. According to Table 6, the material of the present invention using a dye as a coloring agent achieves the target appearance and gloss within a weldable film thickness range. On the other hand, comparative materials using colored pigments have poor appearance and gloss within the weldable film thickness range, and are also poor in press formability, corrosion resistance, and adhesion. In addition, among the examples of the present invention, the material of the present invention using an azo metal complex dye as the dye has excellent light fastness, and
It shows excellent corrosion resistance due to the anticorrosion effect of the dye itself.

Example (2) and Comparative Example (2) Using azo dyes, phthalocyanine dyes, and azo metal complex dyes as dyes, the influence of the thickness of the colored film on each property was investigated. The results are shown in Tables 7 to 10. Figure 3 summarizes the weldability measurement results of Example (2) and Comparative Example (2). Weldability begins to decline when the coating thickness exceeds 2.5 μm, and especially when the coating thickness exceeds 3.0 μm. It turns out that proper welding becomes impossible.

Example (3) and Comparative Example (3) Using phthalocyanine dyes and azo metal complex dyes as dyes, the influence of the amount of dye blended in the colored film on each property was investigated. The results are shown in Tables 11 to 14.

Example (4) and Comparative Example (4) Using an azo dye or an azo metal complex dye as the dye, type of plating, presence or absence of chromate film, chromate treatment method, amount of chromium deposited, base resin The effects of the type and baking temperature on each property were investigated. The results are shown in Tables 15 to 18.

Example (5) and Comparative Example (5) Characteristics of colored steel sheets were investigated using azo metal complex dyes and azo dyes as dyes and containing solid lubricants and particulate rust preventive pigments as additives. Ta. At the same time, we also investigated the effects of the amounts of solid lubricant and particulate rust-preventing pigment on each property. The results are shown in Tables 19 to 24.

Example (6) and Comparative Example (6) Organic solvent-soluble azo metal complex dye (azo chromium complex dye)
Corrosion resistance and other properties were investigated for the material of the present invention having a colored film containing dye and a comparative material having a clear film containing no dye. The results are shown in Tables 25 and 26. For comparison, the same table shows No. 1 of Comparative Example (4). 3 (colored film material without chromate) was also described. As is clear from the same table, the present invention material (Zn plating base + chromate 50 mg/m2 + colored film 1.5 μm) is different from the comparative material having a clear film (Zn plating base + chromate 50 mg/m2).
mg/m2+clear film). In this way, the reason why the material of the present invention has superior corrosion resistance compared to comparative materials is that in addition to the barrier effect of the chromate film and resin film, the azo metal complex dye blended in the resin has a strong effect on the inside of the colored film at the molecular level. uniformly and densely distributed,
The first step is to improve the barrier effect of the resin film. Furthermore, it is presumed that the material of the present invention provides excellent corrosion resistance not only due to the colored film alone, but also due to the interaction between the colored film and the underlying chromate, and this indicates that the material of Comparative Example (4) No. This is clear even when compared with the corrosion resistance of the colored film material without chromate in No. 3. That is, the above-mentioned comparative material, in which only a colored film was formed on a Zn-plated steel sheet without forming an underlying chromate film, was significantly inferior in corrosion resistance to the present invention material. The corrosion resistance of the present invention material compared to comparative materials is not simply due to the added barrier effect of the chromate film;
It is clear that this is due to a synergistic effect between the base chromate film and the colored film containing the azo metal complex dye.

Example (7) and Comparative Example (7) The surface of a Zn-12% Ni alloy plated steel sheet whose surface had been previously degreased was coated with a chromium coating amount of 50 m using continuous roll coater equipment.
A coating-type chromate film of g/m2 was formed, and a composition in which 70 parts by weight of an organic solvent-soluble azo dye (No. 3 in Table 2) was blended with 100 parts by weight of epoxy resin (No. 1 in Table 1) was continuously mixed. The material of the present invention was coated using roll coater equipment and thermally cured at 210° C. to produce a colored film having a thickness of 1.5 μm. In addition, as a comparison material, a Zn-12%Ni alloy plated steel sheet with a degreased surface was immersed in a 5% by weight nitric acid aqueous solution at 25°C for 5 seconds, and then washed with water and dried to form a black film. Ta.

In the method of the comparative example, approximately 0.0.
When the 03m2 Zn-Ni plated steel sheet was blackened,
The blackness of the steel plate gradually decreased, and after approximately 0.04 m2 of treatment, the blackness L value exceeded 20, making continuous blackening treatment impossible. On the other hand, in the case of the material of the present invention, continuous treatment was possible as long as the prepared colored film composition could be supplied.

After preparing each test material, a portion of the residue of the colored film composition liquid used to form the film of the present invention material was collected from the tray of the roll coater, and was also used for the blackening treatment of the comparative material. A portion of the nitric acid aqueous solution was sampled, and the amount of zinc in each solution was measured by atomic absorption spectrometry (Z-8100 manufactured by Hitachi, Ltd.) to examine the amount of zinc eluted from the plating film. As a result, the amount of zinc in the solution used to form the film on the inventive material was less than trace, but the amount of Zn-12%Ni plating eluted from the solution used to treat the comparative material at about 5 g per 1 m2 of treated area. Zinc equivalent to

Next, a corrosion resistance test was conducted on the above-mentioned materials of the present invention and comparative materials by the same method as described above (salt spray test). As a result, the material of the present invention showed no white rust on the flat plate portion even after 480 hours, but the comparative material completely developed white rust after about 1 to 2 hours. After the comparative material was blackened, a coating type chromate film with a chromium adhesion amount of 50 mg/m2 was formed, and Table 1 No. 1 clear resin film 1
．． When it was formed to a thickness of 5 μm and a corrosion resistance test was conducted again, white rust was found to be about 5% after 240 hours of salt water spraying.
It was observed that the corrosion resistance was improved compared to the comparative material that did not form a chromate film or a resin film. However, in the case of the colored steel sheet according to the present invention, the processing process is ``plated steel sheet → chromate film formation → colored film formation'', whereas in the case of the above comparative material, it is necessary to produce a black steel sheet with sufficient corrosion resistance for home appliances. requires "Zn-Ni alloy plated steel sheet → reactive blackening treatment → (washing and drying) → chromate film formation → clear resin film formation", and when comparing the two processes,
In the present invention, the reactive coloring treatment step and the subsequent washing and drying steps are completely unnecessary, so it can be said that the material of the present invention is extremely advantageous in terms of the treatment process.

[0089]

[Table 1]

[0090]

[Table 2]

[0091]

[Table 3]

[0092]

[Table 4]

[0093]

[Table 5]

[0094]

[Table 6]

[0095]

[Table 7]

[0096]

[Table 8]

[0097]

[Table 9]

[0098]

[Table 10]

0099

[Table 11]

[0100]

[Table 12]

[0101]

[Table 13]

[0102]

[Table 14]

[0103]

[Table 15]

[0104]

[Table 16]

[0105]

[Table 17]

[0106]

[Table 18]

[0107]

[Table 19]

[0108]

[Table 20]

[0109]

[Table 21]

[0110]

[Table 22]

[0111]

[Table 23]

[0112]

[Table 24]

[0113]

[Table 25]

[0114]

[Table 26]

(*1) See Table 1 (*2) See Table 2 (*3) Represents parts by weight of coloring agent based on 100 parts by weight of base resin. (*4) See Table 3 (*5) Represents parts by weight of solid lubricant relative to 100 parts by weight of base resin. (*6) See Table 4 (*7) Represents parts by weight of particulate rust-preventing pigment relative to 100 parts by weight of base resin.

[0116]

Effects of the Invention According to the present invention described above, since the colored film is thinner (~3 μm) than conventional coated steel sheets, welding is possible, and the coloring is uniform in color and has an excellent glossy appearance. A steel plate is obtained. Moreover, this colored steel sheet is excellent not only in appearance and weldability but also in the adhesion of the colored film, workability, corrosion resistance, and light fastness. Furthermore, since it can be manufactured by coating and baking using existing roll coater equipment, compared to reactive etching type colored steel sheets,
Steel plates with various colors can be obtained, and since there is no problem of bath deterioration due to plating elution, productivity can be greatly improved, and colored steel plates can be provided that are extremely superior in terms of both performance and productivity. It is. In addition, colored steel sheets containing azo metal complex dyes have better corrosion resistance,
Provides light fastness.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a film structure in a steel sheet of the present invention.

FIG. 2 shows the range of the blending amount of the dye and the thickness of the colored film in the present invention.

FIG. 3 shows the relationship between the colored film thickness and weldability of test materials in Examples.

Claims (6)

[Claims] [Claim 1] A chromate film with a chromium adhesion amount (metal chromium equivalent) of 10 to 200 mg/m2 on the surface of zinc or zinc-based alloy plating, a thermosetting resin as a base resin on the top of the chromate film, A weldable colored steel sheet having a colored film (excluding the black film) having a thickness of 0.3 to 3.0 μm, which is made by blending 1 to 200 parts by weight of a dye as a coloring agent to 100 parts by weight of this base resin. [Claim 2] Amount of chromium deposited on the surface of zinc or zinc-based alloy plating (metallic chromium equivalent) of 10 to 200 mg/m
2, and on the top of the chromate film, a thermosetting resin is used as a base resin, and 1 to 200 parts by weight of a dye as a coloring agent is added to 100 parts by weight of this base resin.
Further, 1 to 100 parts by weight of solid lubricant is added to the film, which has a thickness of 0.
A weldable colored steel sheet having a colored film of 3 to 3.0 μm (excluding the black film). [Claim 3] Amount of chromium deposited on the surface of zinc or zinc-based alloy plating (metallic chromium equivalent) of 10 to 200 mg/m
2, and on the top of the chromate film, a thermosetting resin is used as a base resin, and 1 to 200 parts by weight of a dye as a coloring agent is added to 100 parts by weight of this base resin.
A weldable colored steel sheet having a colored film (excluding a black film) having a thickness of 0.3 to 3.0 μm and further containing 1 to 100 parts by weight of a particulate anticorrosive pigment. [Claim 4] Amount of chromium deposited on the surface of zinc or zinc-based alloy plating (metallic chromium equivalent) of 10 to 200 mg/m
2, and on the top of the chromate film, a thermosetting resin is used as a base resin, and 1 to 200 parts by weight of a dye as a coloring agent is added to 100 parts by weight of this base resin.
Furthermore, weldable coloring with a colored film (excluding black film) with a thickness of 0.3 to 3.0 μm containing 1 to 100 parts by weight of a solid lubricant and 1 to 100 parts by weight of a particulate rust-preventive pigment. steel plate. [Claim 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. The weldable colored steel sheet according to claim 2 or 4, which contains one or more selected from the group consisting of polyalkylene glycol. 6. The weldable colored steel sheet according to claim 3, wherein the particulate rust preventive pigment contains one or more selected from the group consisting of a hardly soluble chromium compound and silica.