JP3412540B2 - Organic coated steel sheet with excellent corrosion resistance - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic coated steel sheet which is most suitable for automobiles, home appliances, building materials, etc. In order to adapt to environmental problems such as volatilization and elution of harmful substances from products, environmentally-friendly surface treatment that does not contain heavy metals such as chromium, lead, cadmium, and mercury that are harmful to the environment and human body during manufacturing and products. It relates to a steel plate.

[0002]

2. Description of the Related Art The purpose of improving corrosion resistance (white rust resistance, red rust resistance) on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet for steel sheets for home appliances, steel sheets for building materials, and steel sheets for automobiles. Therefore, a steel sheet that has been subjected to a chromate treatment with a treatment liquid containing chromic acid, dichromic acid or a salt thereof as a main component is widely used. This chromate treatment is an economical treatment method that has excellent corrosion resistance and can be performed relatively easily.

However, since the chromate treatment uses hexavalent chromium which is a pollution control substance, chromate has a bad influence on the human body in the treatment process, and it is difficult to dispose of the chromium sludge after the wastewater treatment. However, there are various problems such as the possibility that hexavalent chromium may be eluted from the product after chromate treatment. For this reason, as chromic acid usage control standards become stricter, management of chromate treatment plants, wastewater treatment, secondary contamination by chromate treatment products, etc. are becoming a problem, and in response to this, each plant has closed wastewater relations. , We are taking measures to prevent chromium ions from being discharged to the outside.
Also, in the process of degreasing the rust preventive oil and press oil adhered to the chromate-treated steel sheet by the user, when an alkaline degreasing liquid is used, the elution of chromium in the degreasing liquid is considerably large, so the degreasing liquid Dechrome treatment is required.

In view of the above, in order to prevent the occurrence of white rust on zinc-based plated steel sheets, many pollution-free treatment techniques have been proposed that do not rely on chromate treatment. Among them, some methods using organic compounds and organic resins have been proposed, and the following methods can be mentioned, for example.

(1) Method using tannic acid (for example,
(JP-A-51-71233) (2) A method using a thermosetting coating material in which an epoxy resin, an amino resin and tannic acid are mixed (for example, JP-A-63-9).
(0581) (3) A method using a mixed composition of an aqueous resin and a polyhydric phenolcarboxylic acid (for example, JP-A-8-325760).
How to utilize the chelating power of tannic acid such as

(4) A surface treatment method in which an aqueous solution of a hydrazine derivative is applied to the surface of a tin plate or a zinc iron plate (for example,
Japanese Patent Publication No. 53-27694, Japanese Patent Publication No. 56-10386
(5) A method of using a rust preventive agent containing an amine addition salt obtained by adding an amine to a mixture of acyl sarcosine and benzotriazole (for example, JP-A-58-130284).
(6) A method using a treating agent in which a heterocyclic compound such as a benzothiazole compound and tannic acid are mixed (for example, JP-A-57-198267).

[0007]

However, these conventional techniques have the following problems. First, all of the above methods (1) to (4) have problems in terms of corrosion resistance and the like. That is, the method (1) has insufficient corrosion resistance, and a uniform appearance after treatment cannot be obtained. In addition, the method of (2) above is a method of forming a thin film (0.1 to 5 μm) directly on a zinc-based or aluminum-based plating surface.
It is not intended to form the rust-preventive film of m), and therefore, even if it is applied in a thin film on the surface of zinc-based or aluminum-based plating, a sufficient anticorrosive effect cannot be obtained. Similarly, the method (3) also has insufficient corrosion resistance.

Furthermore, the above method (4) is not applied to a zinc-based or aluminum-based plated steel sheet, and even if it is applied to a zinc-based or aluminum-based plated steel sheet, the obtained film has a network structure. It does not have sufficient barrier properties, and therefore has insufficient corrosion resistance. In addition, Japanese Examined Japanese Patent Publication No. 53-23772
JP-B-56-10386, a water-soluble polymer compound (polyvinyl alcohol, maleic acid ester copolymer, acrylic acid ester copolymer, etc.) is mixed with an aqueous solution of a hydrazine derivative in order to improve the uniformity of the film. However, sufficient corrosion resistance cannot be obtained with a simple mixture of an aqueous solution of a hydrazine derivative and a water-soluble polymer compound.

Further, the above methods (5) and (6) are not aimed at forming a rust-preventive coating on the surface of a zinc-based or aluminum-based plated steel sheet in a short time.
Even if the treating agent is applied to the surface of the plated steel sheet, excellent corrosion resistance cannot be obtained because there is no barrier against corrosion factors such as oxygen and water. Regarding the method (6), mixing with a resin (epoxy resin, acrylic resin, urethane resin, nitrocellulose resin, vinyl chloride resin, etc.) as an additive is also described, but a complex such as a benzothiazole compound is mentioned. Sufficient corrosion resistance cannot be obtained with a simple mixture of a ring compound and a resin.

Further, in any of the above methods (1) to (6), in order to remove the oil applied to the surface by pressing or the like, alkaline degreasing of about pH 9 to 11 by spraying or the like is carried out under practical conditions. In the above, there is a problem that the film is peeled off or damaged by alkali degreasing, and the corrosion resistance cannot be maintained. Therefore, these methods are not suitable for practical use as a method for forming a rust preventive film. Therefore, an object of the present invention is to solve the problems of the prior art and to provide an organic coated steel sheet which is safe and harmless in the manufacturing process and in use, and which has excellent corrosion resistance.

[0011]

Means for Solving the Problems As a result of intensive studies made by the present inventors in order to solve the above problems, as a result, a chemical conversion film other than a chromate film was formed on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, if necessary. By forming a treatment film and then forming an organic film containing a specific rust preventive additive, it is pollution-free and excellent in corrosion resistance, without the need for chromate treatment that may adversely affect the environment or the human body. It has been found that an organic coated steel sheet can be obtained. The present invention has been made on the basis of such knowledge, and the characteristic configuration is as follows.

[0012]

[1] A film-forming organic resin (A) 100 is formed on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet.
With respect to parts by weight (solid content), zinc phosphate and / or aluminum phosphate (a) and calcium compound (b)
1 to 100 parts by weight (solid content) in total ( excluding chromium compound containing calcium ), and content of zinc phosphate and / or aluminum phosphate (a) and calcium compound (b) (Solid content) weight ratio (a) /
(B) is 1/99 to 99/1, and the film thickness is 0.1 to 5
An organic coated steel sheet having excellent corrosion resistance, which has an organic coating of μm.

[0014]

[2] A film-forming organic resin (A) 100 is formed on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet.
With respect to parts by weight (solid content), zinc phosphate and / or aluminum phosphate (a) and calcium compound (b)
(Excluding chromium compound containing calcium) and 1 to 100 parts by weight (solid content) in total, solid lubricant (c)
1 to 80 parts by weight (solid content), and a weight ratio (a) / (b) of zinc phosphate and / or aluminum phosphate (a) and calcium compound (b) content (solid content).
Is 1/99 to 99/1 and has an organic film having a film thickness of 0.1 to 5 μm, which is an organic coated steel sheet excellent in corrosion resistance.

[0016][3] On the organic coated steel sheet of [1] or [2] above
And zinc phosphate and / or phosphate in the organic film.
Luminium (a) and calcium compound (b)
5 to 100 parts by weight (solid content) in total, and organic peel
Zinc phosphate and / or aluminum phosphate in the film
Of the content (solid content) of (a) and the calcium compound (b)
The weight ratio (a) / (b) is 98 / 2-40 / 60.
An organic coated steel sheet with excellent corrosion resistance, characterized by: [4] In the organic coated steel sheet according to [1] or [2] above, the organic peel
Zinc phosphate and / or aluminum phosphate in the film
The total amount of (a) and the calcium compound (b) is 5 to 5.
100 parts by weight (solid content) of phosphorus in the organic film
Zinc and / or aluminum phosphate (a) and calcium
Weight ratio (a) of content (solid content) of sium compound (b)
/ (B) is 95/5 to 40/60
Organic coated steel sheet with excellent corrosion resistance. [5] In the organic coated steel sheet according to any one of the above [1] to [4],
The film-forming organic resin (A) is OH group and / or COO
Resistant to organic polymers having H groups
Organic coated steel sheet with excellent eating habits. [6] In the organic coated steel sheet of [5] above, an organic polymer resin
Excellent corrosion resistance, characterized by being a thermosetting resin
Organic coated steel sheet.

[7] The organic coated steel sheet according to the above [6], wherein the thermosetting resin is an epoxy resin and / or a modified epoxy resin, which is excellent in corrosion resistance. [8] In the organic coated steel sheet according to any one of the above [1] to [7],
An organic coated steel sheet having excellent corrosion resistance, characterized by having a chemical conversion treatment film containing no hexavalent chromium on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and having an organic coating on the surface thereof.

The basic characteristics of the organic coated steel sheet of the present invention are:
If necessary, after forming a chemical conversion treatment film on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet, a film-forming organic resin (A), preferably an organic polymer resin having an OH group and / or a COOH group ( More preferably a thermosetting resin, particularly preferably an epoxy resin and / or a modified epoxy resin), and zinc phosphate and / or aluminum phosphate (a) and calcium as rust preventive additives.
Compound (b) (excluding chromium compounds containing calcium)
The point is that an organic film was formed with an appropriate amount of

By adding an appropriate amount of zinc phosphate and / or aluminum phosphate (a) as an anticorrosive additive to the organic film , excellent anticorrosion performance (self-healing action at film defects) can be obtained. . The anticorrosion mechanism obtained by blending zinc phosphate and / or aluminum phosphate (a) in the organic film is considered to proceed in the following reaction steps.

[First step]: In a corrosive environment,
Zinc and aluminum, which are plating metals, are eluted. [Second step]: Zinc phosphate and / or aluminum phosphate undergoes a hydrolysis reaction and dissociates into phosphate ions. [Third step]: The eluted zinc ions and aluminum ions undergo a complex formation reaction with phosphate ions to form a dense and sparingly soluble protective film, which seals the film defects.
Suppresses corrosion reaction.

Further, in addition to the anticorrosive action of zinc phosphate and / or aluminum phosphate as described above, OH groups and / or C are added to the film-forming organic resin (A) of the organic film.
By using an organic polymer resin having an OOH group (preferably a thermosetting resin, more preferably an epoxy resin and / or a modified epoxy resin), the organic polymer resin reacts with a crosslinking agent to form a dense barrier film. This barrier film is excellent in the ability to suppress permeation of corrosion factors such as oxygen, and the OH and COOH groups in the molecule provide a strong bond with the base material, so that particularly excellent corrosion resistance is obtained. .

Furthermore, in the organic coated steel sheet of the present invention, calcium compound (b) (calcium is contained in the organic coating together with zinc phosphate and / or aluminum phosphate (a).
By further adding (including the chromium compound contained therein) , a further corrosion resistance improving effect can be obtained. The reason for this is
It can be considered as follows. Since the self-repairing action of zinc phosphate and / or aluminum phosphate is triggered by the elution of the plating metal (first step) as described above, the corrosion reaction is suppressed at the very early stage of corrosion, but the corrosion reaction Cannot be completely suppressed. On the other hand, by using a calcium compound, which is a metal that is a base metal rather than zinc or aluminum, the preferential elution of calcium rather than the plating metal acts as the above-mentioned trigger, and thereby corrosion does not depend on the elution of the plating metal. The reaction can be suppressed. Due to such a mechanism, it is considered that a combined rust preventive effect can be obtained by using zinc phosphate and / or aluminum phosphate in combination with a calcium compound.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention and the reasons for limitation thereof will be described below. Examples of the zinc-based plated steel sheet as the base of the organic coated steel sheet of the present invention include a galvanized steel sheet and Zn-Ni.
Alloy-plated steel sheet, Zn-Fe alloy-plated steel sheet (electroplated steel sheet and galvannealed steel sheet), Zn-Cr
Alloy-plated steel sheet, Zn-Mn alloy-plated steel sheet, Zn-C
o alloy plated steel sheet, Zn-Co-Cr alloy plated steel sheet,
Zn-Cr-Ni alloy plated steel sheet, Zn-Cr-Fe alloy plated steel sheet, Zn-Al alloy plated steel sheet (for example, Z
n-5% Al alloy plated steel plate, Zn-55% Al alloy plated steel plate), Zn-Mg alloy plated steel plate, Zn-Al-
It is possible to use Mg plated steel sheets, and further zinc-based composite plated steel sheets (for example, Zn—SiO ₂ dispersion plated steel sheets) in which metal oxides, polymers and the like are dispersed in the plating films of these plated steel sheets.

In addition, it is also possible to use a multi-layer plated steel sheet obtained by plating two or more layers of the same kind or different kinds among the above-mentioned plating. Further, as the aluminum-based plated steel sheet which is the base of the organic coated steel sheet of the present invention, an aluminum-plated steel sheet, an Al-Si alloy-plated steel sheet, or the like can be used. Further, as the plated steel sheet, a steel sheet surface may be preliminarily plated with Ni or the like and then various kinds of plating as described above may be performed thereon. As the plating method, any of an electrolysis method (electrolysis in an aqueous solution or electrolysis in a non-aqueous solvent), a melting method and a vapor phase method can be adopted.

If necessary, in order to prevent film defects or unevenness when a chemical conversion treatment film or an organic film is formed on the surface of the plating film, alkaline degreasing, solvent degreasing, or surface conditioning may be performed on the surface of the plating film in advance. A treatment such as a treatment (alkaline surface conditioning treatment or acidic surface conditioning treatment) can be performed in advance. In addition, in order to prevent blackening (a kind of oxidation phenomenon of the plating surface) under the use environment of the organic coated steel sheet, iron group metal ions (Ni
Surface conditioning treatment with an acidic or alkaline aqueous solution containing ions, Co ions, Fe ions) can be performed. When an electrogalvanized steel sheet is used as a base steel sheet, iron group metal ions (Ni ions, Co ions, Fe ions) are added to the electroplating bath for the purpose of preventing blackening.
It is possible to add 1 ppm or more of these metals in the plating film by adding. In this case, there is no particular upper limit on the iron group metal concentration in the plating film.

On the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet, a chromate film (6
A chemical conversion treatment film other than a chemical conversion treatment film containing valent chromium can be formed. The chemical conversion treatment film is formed for the purpose of suppressing the activity of the plated steel sheet and improving the corrosion resistance and the adhesion, and the type thereof is not limited as long as it is a chemical conversion treatment film containing no hexavalent chromium.

As the chemical conversion treatment film containing no hexavalent chromium, for example, (1) phosphate treatment film (2) molybdate or tungstate treatment film, passivation film such as phosphoric acid / molybdic acid treatment film, 3) Alkali silicate treatment film composed of alkali metal oxide such as lithium oxide and silicon oxide (4) Composite oxide film composed of trivalent chromium (5) Inorganic film such as oxide film composed of titanium oxide and zirconium oxide Can be applied.

In addition to the above inorganic coatings, for example, (6) organic resin coating or organic composite silicate coating (7) chelate-forming organic coating of tannic acid, phytic acid, phosphonic acid, etc. (8) above (1), A composite film or the like in which an organic resin is mixed in the inorganic film of (2) or (3) can be applied. Among the above, a hardly soluble film containing silicon oxide (for example, an alkali silicate film) is most preferable from the viewpoint of suppressing white rust of zinc.

An organic resin may be added to the above chemical conversion coating for the purpose of improving workability and corrosion resistance. As this organic resin, an epoxy resin, a urethane resin, an acrylic resin, an acrylic-ethylene copolymer, an acrylic-styrene copolymer, an alkyd resin, a polyester resin, an ethylene resin, or the like can be used.
These can be supplied as a water-soluble resin and / or a water-dispersible resin. Furthermore, in addition to these water-dispersible resins,
It is effective to use a water-soluble epoxy resin, a water-soluble phenol resin, a water-soluble butadiene rubber (SBR, NBR, MBR), a melamine resin, a blocked isocyanate, an oxazoline compound or the like as a crosslinking agent.

In the above chemical conversion treatment film, polyphosphate salt is added as an additive for further improving the corrosion resistance.
Phosphates (eg, zinc phosphate, aluminum dihydrogen phosphate, zinc phosphite, etc.), molybdates, phosphomolybdates (aluminum phosphomolybdate, etc.), organic phosphoric acids and salts thereof (eg, phytic acid) , Phytate, phosphonic acid, phosphonate and their metal salts, alkali metal salts), organic inhibitors (for example, hydrazine derivatives, thiol compounds, dithiocarbamates, etc.), organic compounds (polyethylene glycol), etc. May be added to.

Further, as other additives, organic coloring pigments (for example, condensed polycyclic organic pigments, phthalocyanine organic pigments, etc.), coloring dyes (for example, organic solvent-soluble azo dyes, water-soluble azo metal dyes, etc.) ), Inorganic pigments (titanium oxide), chelating agents (thiols, etc.), conductive pigments (eg, metal powders such as zinc, aluminum, nickel, iron phosphide, antimony-doped tin oxide, etc.), coupling agents (eg, A silane coupling agent, a titanium coupling agent, etc.), a melamine / cyanuric acid adduct, etc. can be added.

Further, for the purpose of preventing blackening (a kind of oxidation phenomenon of the plating surface) under the use environment of the organic coated steel sheet, these chemical conversion treatment films are coated with iron group metal ions (Ni ion, C ion).
O ions, Fe ions), preferably Ni ions may be added. In this case, the desired effect can be obtained if the concentration of the iron group metal ion is 1/10000 mol or more with respect to 1 mol of the (β) alkaline earth metal ion in the treatment composition. The upper limit of the concentration of the iron group metal ion is not particularly specified, but it is set to such an extent that the corrosion resistance is not affected as the concentration increases. The thickness of these chemical conversion coatings is 3 μm or less. This is because if the film thickness exceeds 3 μm, the workability and conductivity decrease. The lower limit is not particularly defined, but may be set to a film thickness that is effective in improving the corrosion resistance.

On the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet, the above chemical conversion treatment film is formed, if necessary, and then an organic film containing a specific rust preventive additive is formed. The base resin for the organic coating is not particularly limited, and any of water-soluble resins, water-dispersible resins, and organic solvent-soluble resins can be used. In particular, from the viewpoint of corrosion resistance, organic resins having an OH group and / or a COOH group can be used. It is preferable to use the polymer resin (A). Of these, thermosetting resins are preferable, and epoxy resins or modified epoxy resins are most preferable.

Examples of the organic polymer resin having an OH group and / or COOH group include epoxy resin, polyhydroxypolyether resin, acrylic copolymer resin, ethylene-acrylic acid copolymer resin, alkyd resin and polybutadiene. Examples thereof include resins, phenol resins, polyurethane resins, polyamine resins, polyphenylene resins, and mixtures or addition polymers of two or more of these resins.

(1) Epoxy resin As the epoxy resin, bisphenol A, bisphenol F, an epoxy resin in which novolac or the like is converted into glycidyl ether, bisphenol A with propylene oxide,
A glycidyl etherified epoxy resin to which ethylene oxide or polyalkylene glycol is added, and further an aliphatic epoxy resin, an alicyclic epoxy resin, a polyether epoxy resin, or the like can be used. These epoxy resins preferably have a number average molecular weight of 1500 or more, especially when curing at low temperature is required. The epoxy resins may be used alone or as a mixture of different types.

Examples of the modified epoxy resin include resins obtained by reacting various modifying agents with the epoxy group or bidroxyl group in the above epoxy resin. For example, an epoxy ester resin obtained by reacting a carboxyl group in a drying oil fatty acid,
Epoxy acrylate resin modified with acrylic acid, methacrylic acid, etc., urethane modified epoxy resin made to react with isocyanate compound, amine added urethane modified epoxy resin made by adding alkanolamine to urethane modified epoxy resin made to react epoxy compound with isocyanate compound, etc. Can be mentioned.

The above polyhydroxypolyether resin is
A polymer obtained by polycondensing a mononuclear or dinuclear dihydric phenol or a mixed dihydric phenol of a mononuclear and a dinuclear type with an approximately equimolar amount of epihalohydrin in the presence of an alkali catalyst. . Representative examples of mononuclear dihydric phenols include resorcin, hydroquinone, and catechol, and representative examples of dinuclear phenols include bisphenol A. These may be used alone or in combination of two or more. May be.

(2) Urethane Resin Examples of the urethane resin include oil-modified polyurethane resin, alkyd polyurethane resin, polyester polyurethane resin, polyether urethane resin and polycarbonate polyurethane resin. (3) Alkyd resin Examples of the alkyd resin include oil-modified alkyd resin, rosin-modified alkyd resin, phenol-modified alkyd resin,
Styrenated alkyd resin, silicon modified alkyd resin,
Examples thereof include acrylic modified alkyd resin, oil-free alkyd resin, and high molecular weight oil-free alkyd resin.

(4) Acrylic resin Examples of the acrylic resin include polyacrylic acid and its copolymer, polyacrylic acid ester and its copolymer, polymethacrylic acid ester and its copolymer, and polymethacrylic acid ester. And copolymers thereof, urethane-acrylic acid copolymer (or urethane-modified acrylic resin), styrene-acrylic acid copolymer, and the like, and further, these resins other alkyd resin, epoxy resin,
A resin modified with a phenol resin or the like may be used.

(5) Ethylene Resin (Polyolefin Resin) Examples of the ethylene resin include ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-based copolymers such as carboxyl-modified polyolefin resins, and ethylene-nonpolymers. Saturated carboxylic acid copolymers, ethylene ionomers and the like can be mentioned, and resins obtained by modifying these resins with other alkyd resins, epoxy resins, phenol resins and the like may be used. (6) Acrylic Silicone Resin Examples of the acrylic silicone resin include those containing a hydrolyzable alkoxysilyl group at the side chain or terminal of an acrylic copolymer as a main agent, and a curing agent added thereto. When these acrylic silicone resins are used, excellent weather resistance can be expected.

(7) Fluororesin As the fluororesin, there is a fluoroolefin copolymer, and examples thereof include alkyl vinyl ether, synchroalkyl vinyl ether, carboxylic acid modified vinyl ester, hydroxyalkyl allyl ether and tetrafluoropropyl as monomers. There is a copolymer obtained by copolymerizing vinyl ether or the like with a fluorine monomer (fluoroolefin). When using these fluororesins,
Excellent weather resistance and excellent hydrophobicity can be expected.

Further, for the purpose of lowering the drying temperature of the resin, the core portion and the shell portion of the resin particles are made of different resin types or cores made of resins having different glass transition temperatures.
A shell type water dispersible resin can be used. Further, using a water-dispersible resin having a self-crosslinking property, for example, by providing an alkoxysilane group to the resin particles, the silanol group is generated by the hydrolysis of the alkoxysilane during the heating and drying of the resin, and the silanol group between the resin particles is generated. Inter-particle cross-linking utilizing the dehydration condensation reaction of can be used. Further, as the resin used for the organic film, an organic composite silicate obtained by combining the organic resin with silica via a silane coupling agent is also suitable.

In the present invention, it is particularly desirable to use a thermosetting resin in order to improve the corrosion resistance and workability of the organic film. In this case, urea resin (butylated urea resin, etc.), melamine resin (butylated melamine resin), butylated urea
Amino resins such as melamine resin and benzoguanamine resin,
A curing agent such as a blocked isocyanate, an oxazoline compound, or a phenol resin can be added.

Among the above-mentioned organic resins, epoxy resin and ethylene resin are preferable in consideration of corrosion resistance, processability and paintability, and in particular, thermosetting having excellent barrier property against corrosion factors such as enzymes. Epoxy resin and modified epoxy resin are particularly suitable. Examples of these thermosetting resins include thermosetting epoxy resins, thermosetting modified epoxy resins, acrylic copolymer resins copolymerized with epoxy group-containing monomers, and epoxy group-containing polybutadiene resins.
Examples thereof include a polyurethane resin having an epoxy group, and an addition product or a condensation product of these resins. One kind of these epoxy group-containing resins can be used alone, or two or more kinds can be mixed and used.

In the present invention, zinc phosphate and / or aluminum phosphate (a) is added as an anticorrosive additive in the organic film.
Is compounded. Zinc phosphate and aluminum phosphate compounded in the organic film are not particularly limited in terms of the skeleton and the degree of condensation of phosphate ions, and any of normal salts, dihydrogen salts, monohydrogen salts and phosphites can be used. Well, the regular salts include all condensed phosphates such as polyphosphates as well as orthophosphates. For example, LF Bosei ZP-DL manufactured by Kikuchi Color Co., Ltd. can be used as zinc phosphate, and K-WHITE manufactured by Teika Co., Ltd. can be used as aluminum phosphate.

These zinc phosphates and aluminum phosphates are dissociated into phosphate ions by hydrolysis in a corrosive environment and undergo a complex formation reaction with the eluted metal to form a protective film.

The amount of zinc phosphate and / or aluminum phosphate (a) in the organic resin film is 1 to 1 with respect to 100 parts by weight (solid content) of the film-forming organic resin (A).
00 parts by weight (solid content), preferably 5 to 80 parts by weight (solid content), more preferably 10 to 50 parts by weight (solid content).
And When the amount of zinc phosphate and / or aluminum phosphate (a) is less than 1 part by weight, the effect of improving corrosion resistance after alkali degreasing is small. On the other hand, if the blending amount exceeds 100 parts by weight, the corrosion resistance decreases, which is not preferable.

Further, in the present invention, a calcium compound (b) (chromium containing calcium ) is contained in the organic film together with the above zinc phosphate and / or aluminum phosphate (a) .
(Excluding the compound) is added in combination, whereby particularly excellent corrosion resistance is obtained. That is, by adding zinc phosphate and / or aluminum phosphate (a) and calcium compound (b) in combination, a particularly excellent anticorrosion effect can be obtained by the above-mentioned composite rust prevention mechanism of both. To be

The calcium compound (b) may be any of calcium oxide, calcium hydroxide and calcium salt, and one or more of these may be used. In addition, the type of calcium salt is not particularly limited, and in addition to single salts containing only calcium as a cation such as calcium silicate, calcium carbonate, and calcium phosphate,
A double salt containing calcium and a cation other than calcium, such as calcium phosphate / zinc and calcium phosphate / magnesium, may be used.

The calcium compound elutes preferentially over the plated metal in a corrosive environment, thereby causing a complex formation reaction with phosphate ions without triggering the elution of the plated metal to form a dense and sparingly soluble protective film. It is thought to form and suppress the corrosion reaction.

When the zinc phosphate and / or aluminum phosphate (a) and the calcium compound (b) are added together in the organic film, the compounding amount is 1% of the film-forming organic resin (A).
1 to 100 parts by weight (solid content) as a total compounding amount of zinc phosphate and / or aluminum phosphate (a) and calcium compound (b) with respect to 00 parts by weight (solid content).
It is preferably 5 to 80 parts by weight (solid content), and the weight ratio (a) / (of the blending amount (solid content) of the zinc phosphate and / or aluminum phosphate (a) and the calcium compound (b). b) is 99/1 to 1/99, preferably 95
/ 5 to 40/60, more preferably 90/10 to 60
/ 40.

If the total amount of zinc phosphate and / or aluminum phosphate (a) and calcium compound (b) is less than 1 part by weight, the effect of improving corrosion resistance after alkaline degreasing is small. On the other hand, if the total blending amount exceeds 100 parts by weight, the corrosion resistance decreases, which is not preferable. Further, the weight ratio (a) / of the compounding amount (solid content) of zinc phosphate and / or aluminum phosphate (a) and calcium compound (b) /
When (b) is less than 1/99, corrosion resistance is poor, while when the weight ratio (a) / (b) exceeds 99/1, zinc phosphate and / or aluminum phosphate (a) and calcium compound (b) The effect of combined addition cannot be sufficiently obtained.

In addition to the above-mentioned rust-preventive additives, the organic film also contains fine oxide particles (eg, silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide) as a corrosion inhibitor. , Molybdate, phosphomolybdate (for example, aluminum phosphomolybdate, etc.), organic phosphoric acid and salts thereof (for example, phytic acid, phytate, phosphonic acid, phosphonate, and metal salts thereof, alkali metal) Salts, alkaline earth metal salts, etc.), organic inhibitors (eg, hydrazine derivatives, thiol compounds, dithiocarbamates, etc.)
Etc. can be added.

If necessary, a solid lubricant (c) may be added to the organic coating for the purpose of improving the workability of the coating. Examples of the solid lubricant applicable to the present invention include the following. (1) Polyolefin wax, paraffin wax:
For example, polyethylene wax, synthetic paraffin, natural paraffin, microwax, chlorinated hydrocarbon, etc. (2) Fluorine resin fine particles: For example, polyfluoroethylene resin (polytetrafluoroethylene resin etc.), polyvinyl fluoride resin, polyvinylidene fluoride Resin, etc.

In addition to the above, fatty acid amide compounds (eg stearic acid amide, palmitic acid amide,
Methylene bis stearamide, ethylene bis stearamide, oleic acid amide, esyl acid amide, alkylene bis fatty acid amide, etc.), metallic soaps (eg calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc.), metal Sulfides (molybdenum disulfide, tungsten disulfide), graphite,
Fluorinated graphite, boron nitride, polyalkylene glycol,
You may use alkali metal sulfate etc.

Among the above solid lubricants, particularly polyethylene wax, fluororesin fine particles (among others, poly 4
Fluorinated ethylene resin fine particles) are suitable. As the polyethylene wax, for example, Ceridust 9615A, Ceridust 3715, Ceridust 3 manufactured by Hoechst Co.
620, Ceridust 3910, Sun Wax 131-P, San Wax 161-P manufactured by Sanyo Kasei Co., Ltd., Chemipearl W-100, Chemipearl W-200, Chemipearl W-500, Chemipearl W-500 manufactured by Mitsui Petrochemical Co., Ltd.
W-800, Chemipearl W-950 and the like can be used.

Further, as the fluororesin fine particles, tetrafluoroethylene fine particles are most preferable, and for example, Lubron L-2 and Lubron L- manufactured by Daikin Industries, Ltd.
5, MP1100, MP12 manufactured by Mitsui DuPont Co., Ltd.
00, full-on dispersion AD1, full-on dispersion AD2, full-on L141J, full-on L15 manufactured by Asahi IC Fluoropolymers Co., Ltd.
0J and FLUON L155J are suitable. Further, among these, a particularly excellent lubricating effect can be expected by using a combination of polyolefin wax and tetrafluoroethylene fine particles.

The compounding amount of the solid lubricant (c) in the organic coating is 1 to 80 relative to 100 parts by weight of the base resin (solid content).
By weight (solid content), preferably 3 to 40 parts by weight (solid content). When the blending amount of the solid lubricant (c) is less than 1 part by weight, the lubricating effect is poor, while when the blending amount exceeds 80 parts by weight, the coating property is deteriorated, which is not preferable.

The organic coating film of the organic coated steel sheet of the present invention comprises a film-forming organic resin (A), zinc phosphate and / or aluminum phosphate (a) and a calcium compound (b).
And a solid lubricant (c), a curing agent, etc. are added as necessary, and as an additive, an organic coloring pigment (for example, a condensed polycyclic organic pigment, a phthalocyanine-based pigment) is added. Organic pigments, etc.), coloring dyes (eg organic solvent-soluble azo dyes, water-soluble azo metal dyes, etc.), inorganic pigments (eg titanium oxide), chelating agents (eg,
Thiol), conductive pigment (for example, metal powder such as zinc, aluminum, nickel, iron phosphide, antimony-doped tin oxide, etc.), coupling agent (for example, silane coupling agent, titanium coupling agent, etc.), melamine·
A cyanuric acid adduct or the like can be added. Further, the coating composition for forming a film containing the above-mentioned base resin and additional components usually contains a solvent (organic solvent and / or water), and further, a neutralizing agent and the like are added if necessary.

The dry thickness of the organic film is 0.1 to 5 μm, preferably 0.3 to 3 μm, more preferably 0.5 to 2
μm. When the film thickness of the organic film is less than 0.1 μm, the corrosion resistance is insufficient, while when the film thickness exceeds 5 μm, the conductivity and workability are deteriorated.

Next, a method of manufacturing the organic coated steel sheet of the present invention will be described. The organic coated steel sheet of the present invention is obtained by subjecting the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet to chemical conversion treatment, if necessary, and then adding zinc phosphate and / or aluminum phosphate to the above-mentioned film-forming organic resin (A).
(A) and calcium compound (b) are added, and if necessary,
Then, the coating composition to which the solid lubricant (c) or the like is added is applied, and the coating composition is heated and dried. The surface of the plated steel sheet may be subjected to alkali degreasing treatment as needed before applying the treatment liquid, and further subjected to pretreatment such as surface conditioning treatment in order to improve adhesion and corrosion resistance.

When a chemical conversion coating is formed on the surface of the plated steel sheet, the method of coating the surface of the plated steel sheet with the treatment liquid may be any of a coating method, a dipping method and a spray method. In the coating method, a roll coater (3 Any coating means such as a roll system, a two roll system, etc.), a squeeze coater, a die coater or the like may be used. Also,
It is also possible to adjust the coating amount, make the appearance uniform, and make the film thickness uniform by an air knife method or a roll squeezing method after the coating treatment with a squeeze coater, the dipping treatment, and the spray treatment.

After coating the treatment liquid as described above, it is washed with water if necessary and then dried by heating. The method of heating and drying the coated treatment liquid is arbitrary, and, for example, a dryer, a hot air oven, a high frequency induction heating oven, an infrared oven or the like can be used. This heat drying treatment is performed at an ultimate plate temperature of 40 to 350 ° C., preferably 80 to 200.
C., more preferably in the range of 80 to 160.degree. If the heating and drying temperature is lower than 40 ° C, a large amount of water remains in the film, resulting in insufficient corrosion resistance. On the other hand, if the heating and drying temperature is higher than 350 ° C., not only is it uneconomical, but also the film is apt to have defects and the corrosion resistance is lowered.

After the chemical conversion treatment film is formed as necessary, the coating composition for forming an organic film is applied.
As a method of applying the coating composition, a coating method, a dipping method,
Any method such as a spray method can be adopted. As a coating method, any method such as a roll coater (3 roll system, 2 roll system, etc.), a squeeze coater, a die coater or the like may be used. Further, it is possible to adjust the coating amount, make the appearance uniform, and make the film thickness uniform by an air knife method or a roll squeezing method after the coating treatment with a squeeze coater or the like, the dipping treatment or the spray treatment.

After application of the coating composition, heating and drying are usually carried out without rinsing with water, but a rinsing step may be carried out after application of the coating composition. A dryer, hot air oven, high-frequency induction heating oven, infrared oven, or the like can be used for the heating and drying treatment. The heat treatment is performed at an ultimate plate temperature of 50 to 350 ° C.
It is desirable to carry out in the range of 80 ° C to 250 ° C. If the heating temperature is lower than 50 ° C, a large amount of water remains in the film, resulting in insufficient corrosion resistance. Also, the heating temperature is 350 ℃
If it exceeds, not only is it uneconomical, but there is a possibility that defects may occur in the film and the corrosion resistance may be reduced.

The present invention includes a steel sheet having the above-mentioned organic coating on both sides or one side. Therefore, examples of the form of the steel sheet of the present invention include the following. (1) One side: plating film-chemical conversion film-organic film, one side: plating film (2) One side: plating film-chemical conversion film-organic film, one side: plating film-chemical conversion film (3) Both sides: plating film- Chemical conversion coating-organic coating (4) One side: plating coating-chemical conversion coating-organic coating, one side: plating coating-organic coating (5) Both sides: plating coating-organic coating

[0067]

Examples As the organic resin for forming an organic film, those shown in Table 3 were used, and in this resin composition, zinc phosphate and / or aluminum phosphate shown in Table 4, calcium compounds shown in Table 5, and Table 6 were used. The solid lubricant shown below was appropriately blended and dispersed for a required time using a paint disperser (sand grinder) to obtain a desired paint composition.

In order to obtain an organic coated steel sheet for home appliances, building materials and automobile parts, the thickness is 0.8 mm and the surface roughness Ra is 1.0.
The plated steel sheet shown in Table 1 obtained by applying various zinc-based plating or aluminum-based plating to a cold-rolled steel sheet having a thickness of μm was used as a treatment original plate, and after the surface of this plated steel sheet was subjected to alkali degreasing treatment, washed with water and dried, Table 2 was used as necessary. The chemical conversion treatment was performed under the conditions shown in. Then, a coating composition for forming an organic film was applied by a roll coater and dried by heating to form an organic film, to produce organic coated steel sheets of the examples of the present invention and comparative examples. The film thickness of the organic film was adjusted by the solid content (heating residue) of the coating composition or the coating conditions (roll rolling force, rotation speed, etc.).

The obtained organic coated steel sheet was evaluated for quality performance (film appearance, white rust resistance, white rust resistance after alkaline degreasing, paint adhesion, workability). The results are shown in Tables 7 to 1 together with the chemical composition coating and the coating composition of the organic coating.
8 shows. The quality performance of the organic coated steel sheet was evaluated as follows.

(1) Appearance of coating film Each sample was visually evaluated for uniformity of coating appearance (with or without unevenness). The evaluation criteria are as follows. ◯: Uniform appearance with no unevenness Δ: Appearance with some conspicuous unevenness ×: Appearance with conspicuous unevenness

(2) White rust resistance For each sample, a salt spray test (JIS-Z-23
71) was carried out and the white rust generation area ratio after a predetermined time was evaluated. The evaluation criteria are as follows. ◎: White rust does not occur ○ +: White rust occurrence area ratio is less than 5% ○: White rust occurrence area ratio is 5% or more and less than 10% ○-: White rust occurrence area ratio is 10% or more and less than 25% △: White rust Occurrence area ratio 25% or more and less than 50% ×: White rust occurrence area ratio 50% or more

(3) White rust resistance after alkaline degreasing For each sample, alkaline treatment liquid CLN-364S (60 ° C., spray 2 manufactured by Nippon Parkerizing Co., Ltd.)
After degreasing with alkali, the salt spray test (JIS
-Z-2371) was carried out, and the white rust area ratio after a predetermined time was evaluated. ◎: White rust does not occur ○ +: White rust occurrence area ratio is less than 5% ○: White rust occurrence area ratio is 5% or more and less than 10% ○-: White rust occurrence area ratio is 10% or more and less than 25% △: White rust Occurrence area ratio 25% or more and less than 50% ×: White rust occurrence area ratio 50% or more

(4) Paint adhesion For each sample, a melamine-based baking paint (film thickness 30
(μm), then soak it in boiling water for 2 hours, immediately cut a grid (10 × 10 grid at 1 mm intervals), apply and peel with an adhesive tape, and remove the coating film. The rate was evaluated. The evaluation criteria are as follows. ◎: No peeling ○: Peeling area ratio less than 5% △: Peeling area ratio 5% or more, less than 20% ×: Peeling area ratio 20% or more

(5) Workability Deep drawing was carried out with a blank diameter of 120 mm and a die diameter of 50 mm (oil-free condition), and the height of molding until cracking was evaluated. The evaluation criteria are as follows. ◎: Through-drawing ○: Molding height of 30 mm or more △: Molding height of 20 mm or more, less than 30 mm ×: Molding height of less than 20 mm

[0075]

[Table 1]

[0076]

[Table 2]

[0077]

[Table 3]

[0078]

[Table 4]

[0079]

[Table 5]

[0080]

[Table 6]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[Table 7]

[0088]

[Table 8]

[0089]

[Table 9]

[0090]

[Table 10]

[0091]

[Table 11]

[0092]

[Table 12]

[0093]

[Table 13]

[0094]

[Table 14]

[0095]

[Table 15]

[0096]

[Table 16]

[0097]

[Table 17]

[0098]

[Table 18]

[0099]

As a conventional reactive chromate-treated steel sheet,
Chromic anhydride: 30 g / l, phosphoric acid: 10 g / l, Na
F: 0.5 g / l, K ₂ TiF ₆ : 4 g / l was used, and the amount of chromium deposited (calculated as metallic chromium) was obtained by spraying at a bath temperature of 40 ° C. and then washing and drying. Of 20 mg / m ² of chromate-treated steel sheet was manufactured. When this was subjected to a salt spray test under the same conditions as in this example, white rust occurred in about 24 hours. Therefore,
From this result and the result of this example, it is understood that the organic coated steel sheet of the present invention can obtain much more excellent corrosion resistance than the conventional chromate-treated steel sheet.

[0101]

As described above, the organic coated steel sheet of the present invention does not contain hexavalent chromium in the coating liquid of the treatment liquid or the product at the time of production, and is an organic coating for use in building materials, home appliances, automobiles, etc. It has a high degree of corrosion resistance as a steel plate, and also has a film appearance,
Excellent in paint adhesion.

Continued Front Page (72) Inventor Satoshi Ando Marunouchi 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Steel Pipe Co., Ltd. (72) Masaaki Yamashita 1-2-1 Marunouchi Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Steel Pipe Co., Ltd. (56) References JP-A-8-318218 (JP, A) JP-A-5-59571 (JP, A) JP-A-10-212586 (JP, A) JP-A-4-56783 (JP, A) Kai-56-113383 (JP, A) JP-A-12-160355 (JP, A) JP-B-62-24505 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 22 / 00-30/00

Claims (8)

(57) [Claims] 1. Zinc phosphate and / or aluminum phosphate (a) and calcium per 100 parts by weight (solid content) of a film-forming organic resin (A) on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet. Compound (b) (mosquito
1 to 100 parts by weight (solid content) in total, and a content of zinc phosphate and / or aluminum phosphate (a) and calcium compound (b) ( excluding chromium compound containing lucium ). (Solid content) weight ratio (a) /
(B) is 1/99 to 99/1, and the film thickness is 0.1 to 5
An organic coated steel sheet having excellent corrosion resistance, which has an organic coating of μm. 2. Zinc phosphate and / or aluminum phosphate (a) and calcium per 100 parts by weight (solid content) of the film-forming organic resin (A) on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet. Compound (b) (mosquito
Excluding inclusive chromium compound calcium) and 1 to 100 parts by weight total of both the (solid), the solid lubricant (c) 1
To 80 parts by weight (solid content), and the weight ratio (a) / (b) of zinc phosphate and / or aluminum phosphate (a) and calcium compound (b) content (solid content) is 1
/ 99-99 / 1, which has an organic film having a film thickness of 0.1 to 5 μm, and is an organic coated steel sheet excellent in corrosion resistance. 3. An organic film containing zinc phosphate and / or
Aluminum phosphate (a) and calcium compound (b)
5 to 100 parts by weight (solid content) in total, and
Zinc phosphate and / or aluminum phosphate in organic film
Content of Ni (a) and Calcium Compound (b) (solid
Min) weight ratio (a) / (b) is 98/2 to 40/60
Corrosion resistance according to claim 1 or 2, characterized in that
Excellent organic coated steel sheet. 4. An organic film containing zinc phosphate and / or
Aluminum phosphate (a) and calcium compound (b)
5 to 100 parts by weight (solid content) in total, and
Zinc phosphate and / or aluminum phosphate in organic film
Content of Ni (a) and Calcium Compound (b) (solid
Min) weight ratio (a) / (b) is 95/5 to 40/60
Corrosion resistance according to claim 1 or 2, characterized in that
Excellent organic coated steel sheet. 5. The organic material having excellent corrosion resistance according to claim 1, 2, 3 or 4, wherein the film-forming organic resin (A) is an organic polymer resin having an OH group and / or a COOH group. Coated steel sheet. 6. The organic coated steel sheet having excellent corrosion resistance according to claim 5, wherein the organic polymer resin is a thermosetting resin. 7. The thermosetting resin is an epoxy resin and / or a modified epoxy resin, according to claim 6.
Organic coated steel sheet having excellent corrosion resistance as described in 1. 8. The zinc-based plated steel sheet or the aluminum-based plated steel sheet has a chemical conversion treatment film containing no hexavalent chromium on the surface thereof, and an organic film as an upper layer thereof. The organic coated steel sheet having excellent corrosion resistance according to 4, 5, 6 or 7.