JPH0941193A - Chromated galvanized steel sheet excellent in lubricity and corrosion resistance and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a chromated galvanized steel sheet excellent in lubricity and corrosion resistance. SOLUTION: In this chromated galvanized steel sheet excellent in lubricity and corrosion resistance, the chromate film is composed of (a) one or >=2 kinds selected from among Cr oxides, Cr hydroxides, and hydrates thereof in the amount of (5 to 200)mg/m<2> per one side of the steel expressed in terms of metallic Cr, (b) one or >=2 kinds among metallic Co and Co compounds in the amount of (1 to 100)mg/m<2> per one side of the steel sheet expressed in terms of metallic Co, and (c) organic resin in the amount of (0.1 to 1000)mg/m<2> per one side of the steel sheet, and further, the chromate film is free from metallic Cr. Moreover, it is preferable to use, as the organic resin, an acrylic resin prepared by using an acrylic ester and a methacrylic ester as essential monomer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chromate-treated zinc-based plated steel sheet having excellent lubricity and corrosion resistance, and a method for producing the same.

[0002]

2. Description of the Related Art It has been widely practiced to subject an upper layer of a zinc or zinc alloy plated steel sheet to a chromate treatment for the purpose of improving corrosion resistance and paintability. The chromate treatment methods are roughly classified into three types: reactive chromate, coating chromate, and electrolytic chromate.

Reactive chromate is a method of forming a chromate film on the plating surface by reacting the plating film with a chromate treatment liquid by spraying or dipping treatment.
It has been performed since ancient times because it can be manufactured at a relatively low cost. However, the quality of the chromate film is unstable and it is difficult to control the adhesion amount because it is affected by the deterioration of the chromate treatment solution due to the accumulation of zinc ions eluted from the plating film and the reactivity of the underlying plating film. I have a problem.

The coating type chromate is a method of forming a chromate film by applying a chromate treatment liquid on the plating surface and baking and drying without washing with water.
By adding silica, an organic resin, or the like to the treatment liquid, it is possible to improve performances such as corrosion resistance and paint adhesion. Therefore, it has been widely applied in recent years. However, there are problems that the appearance is likely to be uneven due to coating unevenness, and the manufacturing cost is high because a baking and drying process at high temperature is required.

Electrolytic chromate is a method of electrochemically forming a chromate film on the surface of plating, and it is easy to manage the liquid and has an excellent appearance uniformity, and it is possible to control the amount of adhesion by the amount of electricity applied. It has the advantage of being. However, although it has excellent paint adhesion, it is inferior in corrosion resistance to the coating type chromate, so that it is only used as a general chromate for a coating base or the like.

In recent years, there has been an increasing demand for higher functionality of chromate-treated zinc-based plated steel sheets, and in addition to corrosion resistance and paint adhesion, functions such as fingerprint resistance and lubricity are also required. In particular, if the chromate-treated zinc-based plated steel sheet has lubricity and can be pressed without oil coating, the degreasing step can be omitted, and the work environment can be improved by preventing the press oil from scattering. There are advantages.

As a method of imparting lubricity to a chromate-treated zinc-based plated steel sheet, for example, Japanese Patent Laid-Open No. 3-16726
Japanese Unexamined Patent Application Publication No. 1-316259 discloses a steel sheet in which a lubricant such as wax or fluororesin is mixed with a base resin and applied and baked on the upper layer of the chromate film, and the lubricant dispersed in the resin film is disclosed. Lubricity is imparted by the action. However, in these steel sheets, there are problems in the stability of the liquid such that the lubricant easily aggregates or precipitates in the base resin liquid and the liquid deteriorates with time.

[0008] Further, these steel sheets have a problem that the manufacturing cost is high because of the two-step treatment of chromate treatment and resin treatment in which a lubricant is mixed. As a method of imparting lubricity by the coating type chromate treatment, JP-A-2-243772 proposes a method of applying a chromate treatment liquid containing zirconium fluoride, silica, phosphate ions, and an organic resin, followed by heating and drying. There is. However, in this method, at the same time as forming the chromate film, the organic resin is heated and dried at a high temperature of 150 to 250 ° C for the purpose of curing the organic resin. Not only the damage but also the deterioration of the appearance of the product due to the galling of resin powder from the steel plate,
It has problems such as deterioration of corrosion resistance after processing.

In addition, the method of incorporating an organic resin in the chromate film by such a coating type chromate treatment cannot sufficiently improve the lubricity, which tends to cause unevenness in appearance due to coating unevenness, and further high temperature drying. Since it is necessary, there are problems such as high equipment cost and manufacturing cost. Electrolytic chromate is most advantageous as a method for solving the above-mentioned problems such as high manufacturing cost and easy occurrence of uneven appearance.

As a method for producing an electrolytic chromate-treated steel sheet having improved corrosion resistance, a bath prepared by adding a metal ion, a fluorine ion or a chlorine ion, an alkali metal or an alkaline earth metal, and a water-soluble resin to JP-B-52-3893 is used. The method of using electrolytic chromate is also described in Japanese Patent Publication No. 4-3.
Japanese Patent No. 0476 proposes a method of electrolytic chromating from a reduced chromic acid bath to which sulfate ions and an organic polymer compound (polyacrylamide) are added. However, with the steel sheets produced by these methods, the corrosion resistance and the paint adhesion are slightly improved, but the lubricity is not improved at all.

Further, as a method for producing an electrolytic chromate-treated steel sheet having improved corrosion resistance and fingerprint resistance, it is disclosed in Japanese Patent Laid-Open No. Hei 5 (1998)
No. 44094 discloses a method using a bath to which Ni ions, silica, sulfate ions and polyethylene glycol are added, and JP-A-5-44095 discloses Ni ions, silica, sulfate ions, aqueous acrylic resins (acrylic acid, acrylic acid,
Resin containing methacrylic acid and acrylamide as monomers)
A method has been proposed in which electrolytic chromating is carried out using a bath to which is added. However, the steel sheets produced by these methods have some improvement in corrosion resistance, fingerprint resistance, paint adhesion, and surface appearance, but they do not provide lubricity that allows press working without oil coating.

As described above, in the known electrolytic chromate treatment, a chromate-treated steel sheet excellent in lubricity capable of press working without oil coating and a method for producing the same have not been known. As described above, in the known art, a chromate-treated zinc-based plated steel sheet having a low cost method, excellent in uniformity of appearance, and having both lubricity and corrosion resistance capable of withstanding continuous pressing with no oil, and Its manufacturing method was unknown.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a chromate-treated zinc-based plated steel sheet excellent in lubricity and corrosion resistance, which solves the above problems, and a method for producing the same.

[0014]

As a result of intensive studies to solve the above problems, the present inventors have found that the chromate film is (a) a predetermined amount of Cr oxide, Cr hydroxide and these. One or more selected from hydrates of
Lubricity when satisfying the following conditions: (b) a predetermined amount of metal Co, one or more kinds of Co compounds, (c) a predetermined amount of organic resin, and no metal Cr present in the chromate film. It was found that a chromate-treated zinc-based plated steel sheet that simultaneously satisfies the corrosion resistance can be achieved.

Further, the present inventors have found that the chromate film is
(A) One or more selected from a predetermined amount of Cr oxide, Cr hydroxide and hydrates thereof, (b) One or two or more selected from a predetermined amount of metal Co, a Co compound,
(C) A chromate-treated zinc-based resin which is composed of a predetermined amount of an organic resin, and the organic resin is an acrylic resin obtained by polymerizing or copolymerizing a specific monomer, and which simultaneously satisfies the lubricity and the corrosion resistance when the conditions are satisfied. It was also found that a plated steel sheet can be achieved.

Further, the present inventors have found that the coating type chromate has problems such as peeling of the organic resin cured by heating and drying at high temperature and high cost due to high temperature heating equipment as described above. We believe that electrolytic chromate treatment, which does not require a heating and drying process at high temperature and is inexpensive in equipment cost, is advantageous, and based on the results, chromate containing an organic resin without containing a lubricant that deteriorates the stability of the treatment liquid. By electrolyzing the treatment liquid, a diligent study was made to impart lubricity and corrosion resistance to the chromate film by a low-cost one-step treatment.

As a result, the present inventors have newly found that the chromate film is provided with lubricity by performing electrolytic chromate treatment under specific conditions, and the present invention has been completed. That is, (a) a predetermined amount of Cr ⁶⁺ and C
r ³⁺ , (b) predetermined amount of Co ²⁺ , (c) predetermined amount of S
By cathodic electrolysis of a high-viscosity chromate treatment liquid containing O ₄ ²⁻ , (d) a predetermined amount of a water-soluble or water-dispersible organic resin, the organic resin is not uniformly dispersed in the chromate film. , Most adhered to the outermost surface of the chromate film,
The surface shape has irregularities. By the surface shape having this unevenness and the sliding resistance reducing action of the organic resin itself,
It was found that the lubricity was remarkably improved.

Further, the steel sheet produced by this method has a barrier effect of the organic resin adhering to the surface of the chromate film,
It has been found that the organic resin has excellent corrosion resistance due to the action of retaining the soluble chromium. The present invention has been completed on the basis of the above-mentioned findings, and the deterioration of the stability of the liquid due to the inclusion of a lubricant, the high cost of the two-step treatment, the peeling of the organic resin cured by the heating and drying step at high temperature, and the high temperature heating facility High-performance chromate-treated zinc-based plated steel sheet that solves all problems such as high cost due to low cost, and can perform press working without oil coating with high lubricity and corrosion resistance by one-step electrolytic chromate treatment at low cost, and The manufacturing method is newly found.

(I) Chromate-treated zinc-based plated steel sheet excellent in lubricity and corrosion resistance: That is, the first and second inventions of the present invention which solve the above problems are chromate excellent in lubricity and corrosion resistance. Related to treated zinc-based plated steel sheet. That is, the constitutional requirement of the first invention of the present invention is a chromate-treated zinc-based plated steel sheet comprising a zinc or zinc alloy plating layer formed on at least one surface of the steel sheet and a chromate film formed on the zinc or zinc alloy plating layer. The chromate film is (a) one or more kinds selected from the range of 5 to 200 mg / m ^{2 in} terms of metal Cr per one side of the steel sheet, Cr oxide, Cr hydroxide and hydrates thereof, and (b) metal. 1 to 100 per side of steel plate in terms of Co
0 mg / m ² of metal Co, one or more kinds of Co compounds, (c) 0.1 to 1000 mg / m per steel plate surface
A chromate-treated zinc-based plated steel sheet excellent in lubricity and corrosion resistance, which is composed of ² organic resins, and is characterized by the absence of metal Cr in the chromate film,
Also, in the first aspect of the present invention, the chromate film is subjected to FT-IR analysis by a reflection method on its surface to obtain 175
It is preferable that the chromate film has an absorption peak at ⁰ to 1720 cm ^{−1 due} to C═O stretching vibration. Further, in the first invention, the organic resin is an acrylic resin, a polyester resin, a urethane resin, or a polyresin. One or more selected from carboxylic acid resins and their derivatives are preferable, and in the first invention, the organic resin is a water-soluble or water-dispersible acrylic resin. Preferably, in the first invention, the organic resin is an acrylic resin obtained by polymerizing or copolymerizing one kind or two or more kinds of acrylic acid ester and methacrylic acid ester, or acrylic acid ester and methacrylic acid ester. And one or more of these as essential monomers, acrylic acid, methacrylic acid, acrylamide, methacrylamide, and One or more and copolymerizing formed by acrylic resin selected from those of the derivative, or is preferably a mixture of those acrylic resins.

A second aspect of the present invention is that the chromate-treated zinc-based plated steel sheet comprises a zinc or zinc alloy plating layer formed on at least one surface of the steel sheet and a chromate film formed on the zinc or zinc alloy plating layer. In (a), the chromate film is (a) converted to metallic Cr and is 5 per one side of the steel plate.
~ 200 mg / m ² of one or more selected from Cr oxides, Cr hydroxides and hydrates thereof,
(B) 1-1000 mg per one side of steel plate in terms of metallic Co
/ M ² of metal Co, one or more of Co compounds,
(C) An acrylic resin composed of 0.1 to 1000 mg / m ² of organic resin per one side of the steel sheet, and the organic resin is obtained by polymerizing or copolymerizing one or more of acrylic acid ester and methacrylic acid ester. Resin, or one or more kinds of acrylic acid ester and methacrylic acid ester as essential monomers, and one or more kinds selected from acrylic acid, methacrylic acid, acrylamide, methacrylamide and derivatives thereof. A chromate-treated zinc-based plated steel sheet having excellent lubricity and corrosion resistance, which is an acrylic resin obtained by copolymerization or a mixture of those acrylic resins.

In the first and second inventions of the present invention, it is preferable that the content of the organic resin in the chromate film is highest on the outermost surface of the chromate film. In the second invention, it is preferable that the chromate film further contains 1 to 1000 mg / m ² of silica per one side of the steel plate, and in the first and second inventions, the chromate film further contains a steel plate. 0.0 per side
It is preferable to contain 1 to 50 mg / m ² of P.

Further, in the first and second inventions, the chromate film further contains 1 to 1000 mg / m ² of metal Ni, in terms of metal Ni, of one or more kinds of Ni and Ni compounds per one side of the steel sheet. The steel sheet may have a total Co content in terms of metallic Co and a Ni content in terms of metallic Ni in the range of 1 to 1000 mg / m ² per one side of the steel sheet.

(II) Black with excellent lubricity and corrosion resistance
Method for producing mate-treated zinc-based plated steel sheet:
The third invention of the present invention, which has solved the problems, provides lubricity and durability.
Manufacturing method of chromate-treated zinc-based plated steel sheet with excellent corrosion resistance
Involved in the law. That is, the constituent features of the third invention of the present invention
Is zinc or zinc compound on at least one surface of the steel sheet.
For zinc-based plated steel sheet with a gold-plated layer,
By applying cathodic electrolysis in the mate treatment liquid
Chromate treatment consisting of forming a chromate film
In the method for producing a zinc-base plated steel sheet,
As a processing solution, (a) the total Cr amount is 1 to 100 g / l, and
Cr³⁺/ Cr with a total Cr weight ratio of 0.05 to 0.3⁶⁺And Cr
³⁺, (B) 0.1-100 g / l Co²⁺, (C) All SO_Four ^2-The amount is 0.1 ~
100g / l and SO_Four ^2-/ Total Cr weight ratio exceeds 0.1
SO less than or equal to 2 _Four ^2-, (D) 0.1-100 g / l water-soluble or
Contains a water-dispersible organic resin and has a pH in the range of 1 to 5.
Yes, using a treatment liquid at a temperature of 20 to 70 ° C, current density of 1 to 1
50 A / dm²As 0.5 ~ 100C / dm²Depending on the amount of electricity
By applying cathodic electrolytic treatment to the system-plated steel sheet,
Chromate treatment characterized by forming a mate film
A method for manufacturing a galvanized steel sheet, and a third invention of the present invention.
Is a water-soluble or water-dispersible organic resin
Resin, polyester resin, urethane resin, polycarbonate
Rubonic acid-based resin and one of these derivatives
Alternatively, it is preferable that two or more kinds are used.
Ming is more preferably water-soluble or water-dispersible.
Machine resin is acrylic acid ester, methacrylic acid ester
Of one or more of
Ril resin, acrylic ester, methacrylic
One or more acid esters as essential monomers
And acrylic acid, methacrylic acid, and acrylic acid
, Methacrylamide and their derivatives
Acrylic tree obtained by copolymerizing one or more of
Fat or a mixture of those acrylic resins
And the third aspect of the present invention is the chromate treatment.
It is preferable that the solution contains 1 to 300 g / l of silica.
The third aspect of the present invention is the chromate treatment liquid.
But 0.01 to 10 g / l PO_Four ^3-Is preferred to contain
New

In the third aspect of the invention, the chromate treatment liquid further contains 0.1 to 100 g / l of Ni ²⁺ , and the total amount of Co ²⁺ and Ni ²⁺ is 0.1 to 100 g / l. It may be a treatment liquid within the range.

[0025]

Hereinafter, the present invention will be described in more detail.
As the zinc or zinc alloy plating of the present invention, zinc or zinc alloy plating such as electrogalvanization, electrozinc alloy plating, hot dip galvanizing, alloying hot dip galvanizing, hot dip zinc-aluminum alloy plating is applied.

For electrogalvanized alloy plating, Ni, C
Electrozinc alloy plating containing one or more of o, Fe, Cr, Mn, etc., dispersion plating containing one or more of inorganic compounds such as silica, alumina, etc., and electrozinc by a combination thereof. All system plating is included. Examples of hot dip galvanizing include Al, Pb, M
It also includes all hot-dip galvanizing containing components such as n, Cr, Si and Fe.

The alloying hot-dip galvanizing is a process in which the hot-dip galvanizing is heat-treated for alloying. In the hot dip zinc-aluminum alloy plating, the aluminum content is as low as about 5% and the aluminum content is 5%.
It is included up to about 5% or higher.

In the present invention, the zinc or zinc alloy plating is formed on at least one surface of the steel sheet, and a chromate film is formed on the above zinc or zinc alloy plating. When it is necessary to clean or activate the surface of the zinc or zinc alloy plating, it is possible to carry out pretreatment such as degreasing, pickling, chemical treatment with alkali or the like and polishing before the chromate treatment.

The chromate-treated zinc-based plated steel sheet having excellent lubricity and corrosion resistance according to the first and second aspects of the present invention will be described below. (I) Chromate-treated galvanized steel sheet excellent in lubricity and corrosion resistance: The method of chromate treatment in the present invention is not particularly limited, and any of reactive chromate, coating chromate and electrolytic chromate methods can be applied.
However, reactive chromate is not suitable because it is difficult to obtain a chromate film having the film composition of the present invention. Further, the coating type chromate can obtain the chromate film of the present invention, but is disadvantageous in that the manufacturing cost is high and the appearance is likely to be non-uniform. The electrolytic chromate is most suitable because it is easy to obtain the chromate film of the present invention, the production cost is low, and the appearance is uniform.

The chromate film of the first invention of the present invention comprises:
(A) One or more selected from Cr oxides, Cr hydroxides and hydrates thereof, (b) Metal Co, C
One or more kinds of o compounds and (c) an organic resin, and no metal Cr is present in the chromate film. The chromate film of the second invention of the present invention comprises (a) C
one or more selected from r oxides, Cr hydroxides and hydrates thereof, (b) one or more of metal Co and Co compounds, and (c) an organic resin,
The organic resin is an acrylic resin obtained by polymerizing or copolymerizing a specific monomer, or a mixture of those acrylic resins.

One or more selected from Cr oxides, Cr hydroxides and hydrates thereof are the basic components constituting the chromate film of the present invention. Cr oxide,
Structural formulas of Cr hydroxides and hydrates thereof are not particularly limited, and examples thereof include Cr ₂ O ₃ , Cr (OH) ₃ , and CrO.
(OH), Cr (OH) CrO ₄ , or a complex of these compounds, and hydrates of these compounds, and also amorphous Cr oxides having no structural formula, Cr hydroxides and these Includes all hydrates. Further, as seen in the known chromate film, a part of the OH group is S
It may be substituted with an anion such as O ₄ ²⁻ , Cl ⁻ , F ⁻ .

As conventionally known, Cr oxide, Cr hydroxide and hydrates thereof not only form a dense barrier film, but also improve the corrosion resistance by the self-repairing action of Cr ⁶⁺ . The ratio of Cr ⁶⁺ in Cr oxide, Cr hydroxide and hydrates thereof is not particularly limited,
In order to fully develop the effect of improving the corrosion resistance by the self-repairing action and at the same time reduce the Cr elution amount as much as possible, the range of 1 to 30 wt% is preferable with respect to the total Cr amount.

When forming a chromate film by electrolytic chromate, metal Cr is usually deposited. Since the metal Cr layer is extremely hard, a crack is formed, and in this crack portion, the exposed zinc or zinc alloy plating layer and the metal Cr layer
An electrochemical microcell is formed with the layer to initiate a corrosion reaction, which causes deterioration of corrosion resistance. First of the present invention
In order to suppress such deterioration of corrosion resistance, the invention of (1) makes it essential that metal Cr is not present in the chromate film.

Here, a method of detecting metallic Cr in the chromate film will be described. The presence or absence of metal Cr in the first invention of the present invention is determined by ESCA (X-ray photoelectron spectroscopy).
It is measured by state analysis according to. As a specific measurement example, using ESCA Lab5 manufactured by VG, sputtering ion species Ar, acceleration energy 3 keV, current density 400 nA / m ² , measurement area 3 mmφ, vacuum degree 3 to.
The sample is sputtered under the condition of 4 × 10 ⁻⁸ until reaching the base metal, and 100 W, 1486.6 eV of AlKα ray is irradiated for detection.

Metal chromate is contained in the chromate film referred to in the present invention.
Is not present means that the sample of metal Cr is not subjected to a penetration analysis under such conditions until the base metal is reached and a peak of metal Cr is not detected. Usually, since the analytical limit is 1 atomic%, for example, if it is composed mainly of Cr (OH) ₃ Cr (OH) CrO ₄ and metal Cr is not detected in the chromate film having a Cr amount of 50 mg / m ² , the metal Cr is not detected. Is less than 1 mg / m ² even if present.

The total content of Cr oxide, Cr hydroxide and their hydrates in the chromate film of the present invention is 5 to 200 mg / m ^{2 in} terms of metal Cr per one side of the steel sheet.
It is. The reason is that if it is less than 5 mg / m ² , desired corrosion resistance cannot be obtained, and if it exceeds 200 mg / m ² , not only is it uneconomical because the effect of improving corrosion resistance is saturated, but the lubricity is adversely affected.

The chromate film of the present invention is made of metal Co, C
One or more o compounds are contained. Metal Co,
Each of the Co compounds has a function of uniformly dispersing and holding the organic resin and a function of holding soluble Cr ⁶⁺ , and this function improves lubricity and corrosion resistance. The type of Co compound is not particularly limited, and examples thereof include CoO and Co.
(OH) ₂ , CoSO ₄ , CoCl ₂ , CoCrO ₄ ,
CoCr ₂ O ₇ or a complex of these compounds, a hydrate of these compounds, and an amorphous Co compound having no structural formula are all included.

Further, since all of these Co compounds have a stable color tone, the presence of the Co compound makes the chromate film as a whole a stable color tone and a beautiful appearance can be obtained. Metal Co, C in the chromate film of the present invention
The total content of one or more o compounds is 1 to 1000 mg / m ² in terms of metal Co per one surface of the steel sheet. The reason for this is that if it is less than 1 mg / m ² , the organic resin is not evenly dispersed and retained, so that the lubricity and corrosion resistance are deteriorated, and if it exceeds 1000 mg / m ² , the effect is saturated, which is uneconomical. This is because the lubricity and corrosion resistance are rather deteriorated.

As for the appearance, if it is less than 1 mg / m ² , there is much unevenness and a beautiful appearance cannot be obtained.
When it exceeds m ² , the appearance is bluish and the original color tone of the chromate steel sheet cannot be obtained. Therefore, the range of 1 to 1000 mg / m ² is preferable. The chromate film of the present invention may further contain one or more of metallic Ni and Ni compounds. Both metallic Ni and Ni compounds are metallic Co and C
By the action similar to that of the o compound, lubricity and corrosion resistance are improved. The type of Ni compound is not particularly limited, and examples thereof include NiO, Ni (OH) ₂ , NiSO ₄ , and NiC.
l ₂ , NiCrO ₄ , NiCr ₂ O ₇ , or a complex of these compounds, a hydrate of these compounds, and an amorphous Ni compound having no structural formula are all included.

These Ni compounds do not have the effect of stabilizing the color tone of the chromate film and providing a beautiful appearance like Co compounds. Therefore, in order to obtain a chromate film having a beautiful appearance, one of Co and Co compounds or two of Co compounds is used.
It is essential to contain at least one kind, and even when one or more kinds of metallic Ni and Ni compounds are partially substituted, a chromate film having a beautiful appearance can be obtained by the action of the Co compound.

The total content of one kind or two or more kinds of metal Ni and Ni compounds in the chromate film is 1 to 1000 mg / m ² in terms of metal Ni per one side of the steel sheet, and 1 of metal Co and Co compounds. Or two or more metal Co
The total of the converted Co content and the Ni content of the metallic Ni and one or more kinds of Ni compounds converted to metallic Ni is in the range of 1 to 1000 mg / m ² per one side of the steel sheet.

The reason for this is that both lower limit values are 1 mg / m 2.
^If it is less than ^2, it has no effect of uniformly dispersing and holding the organic resin, so that the lubricity and corrosion resistance are deteriorated, and if the upper limit of any of them exceeds 1000 mg / m ² , the effect is saturated and not only uneconomical. This is because the lubricity and the corrosion resistance are rather deteriorated. The chromate film of the present invention contains an organic resin. The organic resin in the chromate film is the most important component in the present invention that mainly improves lubricity. The reason that the organic resin improves the lubricity is to reduce the sliding resistance on the surface of the chromate film during press working. The organic resin also contributes to the improvement of corrosion resistance due to the barrier effect.

The organic resin used in the present invention is not particularly limited as long as it is a water-soluble or water-dispersible organic resin which is stable in the chromate treatment liquid, and examples thereof include acrylic resin, polyester resin and urethane. Examples thereof include water-soluble or water-dispersible organic resins containing hydrophilic resins such as carboxyl group, hydroxyl group, sulfonic acid group, amino group, and the like.

Examples of the polycarboxylic acid resin used in the present invention include maleic anhydride-olefin copolymers, maleic anhydride-styrene copolymers and esterified products thereof. The content of the organic resin in the chromate film of the present invention is 0.1 to 1 per one side of the steel plate.
It is 000 mg / m ² . The reason for this is 0.1 mg / m
^If it is less than ² , the lubricity improving effect does not appear, and 1000 mg /
This is because if it exceeds m ² , the surface of the chromate film becomes rough and the lubricity deteriorates.

The chromate film of the present invention is preferably a chromate film showing an absorption peak due to C = O stretching vibration at 1750 to 1720 cm ^-1 by subjecting its surface to FT-IR analysis by a reflection method. In order to achieve the chromate-treated zinc-based plated steel sheet having excellent lubricity and corrosion resistance of the present invention, the present inventors have added various organic resins to the chromate film and investigated its lubricity and corrosion resistance, and at the same time, chromate film. The surface of F by reflection method
The research which analyzed by T-IR analysis has been repeated.

As a result, it was found that a chromate film having an absorption peak at 1750 to 1720 cm ^-1 due to C = O stretching vibration has the best lubricity by FT-IR analysis by the reflection method. It should be noted that even with a chromate film showing an absorption peak due to the same C = O stretching vibration, 1780
Chromate film showing an absorption peak near cm ^-1 or 17
The chromate film showing an absorption peak near 10 cm ^-1 is
It was found that the lubricity was inferior to that of a chromate film showing an absorption peak at 1750 to 1720 cm ^-1 .

For this reason, in the present invention, the surface is subjected to FT-IR analysis by the reflection method so that 1750 to 1720 can be obtained.
A chromate film showing an absorption peak due to C = O stretching vibration at cm ^-1 is most preferable. The reason for this is not clear,
A C═O bond having an absorption peak due to C═O stretching vibration at 1750 to 1720 cm ⁻¹ is a Cr oxide surrounding,
Cr hydroxides and their hydrates, metallic Co, Co
It is considered that this is because the surface of the chromate film is changed to a form having excellent lubricity such that sliding resistance is reduced by binding with the compound in some form.

The organic resin preferably used in the present invention is 1750 to 1720 in the FT-IR analysis.
The resin is not particularly limited as long as it is a resin that forms a chromate film exhibiting an absorption peak due to C = O stretching vibration at cm ^-1 . For example, one or two or more of acrylic acid ester and methacrylic acid ester are polymerized or copolymerized. Or one or more of acrylic acid ester and methacrylic acid ester as essential monomers, and one or more selected from acrylic acid, methacrylic acid, acrylamide, methacrylamide, and derivatives thereof. An acrylic resin, a polyester resin, a urethane resin, a polycarboxylic acid resin esterified product obtained by copolymerizing two or more kinds thereof, or a mixture of these resins is preferable.

Here, in the present invention, the chromate film is a chromate film which exhibits an absorption peak at 1750 to 1720 cm ⁻¹ by C═O stretching vibration by subjecting the surface to FT-IR analysis by a reflection method. Will be described with reference to the drawings. FIG. 1 shows the surface of a chromate film which is particularly excellent in lubricity using an ethyl acrylate-methyl methacrylate copolymer as an organic resin according to the present invention, using FT-IR and a reflection method (incident angle 70 °). It is an example of the spectrum measured by.

The peak P in FIG. 1 is the absorption peak due to the C = O stretching vibration, and the peak position is 1735 cm ^-1 . Since the absorption peak is a sharp peak, it can be easily confirmed. The organic resin used in the present invention is preferably a water-soluble or water-dispersible acrylic resin. This is because the properties peculiar to acrylic resins are excellent in lubricity and corrosion resistance as compared with other resins.

As the water-soluble or water-dispersible acrylic resin, one or more selected from acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, acrylamide, methacrylamide, and derivatives thereof are polymerized or All acrylic resins obtained by copolymerization are included. Examples of these acrylic resins include polyacrylic acid, polymethacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, polyacrylamide, acrylic acid ester-methacrylic acid ester copolymer, acrylic acid-acrylic acid ester-methacrylic acid ester. Copolymer, methacrylic acid-acrylic acid ester-
Examples thereof include methacrylic acid ester copolymers, their derivatives, and mixtures thereof.

Examples of the acrylic (meth) acrylic acid ester include alkyl (meth) acrylic acid such as methyl (meth) acrylic acid and ethyl (meth) acrylic acid, and cyclo (meth) acrylic acid such as cyclohexyl (meth) acrylic acid. Acrylic (methacrylic) such as alkyl and phenyl acrylic (methacrylic) acid
All acid esters are included.

The organic resin used in the present invention is more preferably one of acrylic acid ester and methacrylic acid ester.
Acrylic resin obtained by polymerizing or copolymerizing one or more kinds, or one or more kinds of acrylic acid ester and methacrylic acid ester as an essential monomer, and acrylic acid, methacrylic acid, acrylamide, methacrylamide It is preferably an acrylic resin obtained by copolymerizing one or two or more selected from these derivatives, or a mixture of these acrylic resins.

This is because these resins are the same as the above-mentioned FT-IR.
This is because it is a resin that forms a chromate film that exhibits an absorption peak due to C = O stretching vibration at 1750 to 1720 cm ^-1 in the analysis, and therefore has excellent lubricity, and at the same time, it has excellent lubricity and corrosion resistance due to the properties inherent to acrylic resins. . Therefore, it is essential to use these resins in the second invention of the present invention.

In the present invention, the content of the organic resin in the chromate film is preferably highest on the outermost surface of the chromate film. The reason for this is that the organic resin is most abundant on the outermost surface of the chromate film, so that the effect of reducing sliding resistance during press working is maximized and the lubricity is most improved.

A method for confirming that the content of the organic resin in the chromate film is highest on the outermost surface of the chromate film will be described with reference to the drawings. In the present invention, the distribution state of the organic resin in the chromate film in the depth direction is determined by AES (Auger electron spectroscopy), ESCA (X-ray photoelectron spectroscopy), GDS (glow discharge spectroscopy), SIMS (secondary ion mass). By using an apparatus capable of elemental analysis in the depth direction, such as an analysis method), the distribution of the C element when the sputtering is performed in the depth direction from the surface of the chromate film toward the base iron by Ar ions is performed.

FIG. 2 shows an example of the result of AES analysis of the chromate film of the present invention using an ethyl acrylate-methyl methacrylate copolymer as an organic resin in the depth direction. As shown in FIG. 2, it can be seen that the analytical value of C is highest on the outermost surface of the chromate film, and the content of the organic resin in the chromate film is highest on the outermost surface of the chromate film.

The chromate film of the present invention preferably further contains 1 mg / m ² or more and 1000 mg / m ² or less of silica per one surface of the steel sheet. This is because the presence of silica in the chromate film not only improves the corrosion resistance due to its barrier effect, but also improves the corrosion resistance because the soluble Cr ⁶⁺ is adsorbed on the silica surface to exhibit a self-repairing action for a long time. This is because. If it is less than 1 mg / m ² , the effect is small. Further, if the content of silica in the chromate film exceeds 1000 mg / m ² , not only is it uneconomical because the effect of improving the corrosion resistance is saturated, but also the lubricity and corrosion resistance are deteriorated, which is not preferable.

It is preferable that the chromate film of the present invention further contains 0.01 mg / m ² or more and 50 mg / m ² or less of P per one surface of the steel sheet. This is because the presence of P in the chromate film improves the corrosion resistance. The reason for this is not clear, but soluble Cr that has a self-repairing effect by combining with Cr oxide and Cr hydroxide in some form
^{This is probably} because it suppresses the elution of ⁶⁺ . 0.01
If it is less than mg / m ² , the effect is small. Further, if the content of P in the chromate film exceeds 50 mg / m ² , the corrosion resistance is rather deteriorated, which is not preferable.

The method for producing a chromate film thus formed is most preferably electrolytic chromate treatment and can be produced by the production method of the third aspect of the present invention described below. Next, a method for producing a chromate-treated zinc-based plated steel sheet having excellent lubricity and corrosion resistance according to the third aspect of the present invention will be described.

(II) Method for producing chromate-treated zinc-based plated steel sheet excellent in lubricity and corrosion resistance: The chromate treatment liquid used in the present invention is (a) Cr ⁶⁺ and Cr ³⁺ ,
(b) Co ²⁺ , (c) SO ₄ ²⁻ , (d) Water-soluble or water-dispersible organic resin. In the present invention, Cr ⁶⁺ and Cr
³⁺ is a basic component of the chromate treatment liquid used in the present invention. The supply of Cr ⁶⁺ is performed by using one kind or two or more kinds of chromic anhydride, chromic acid or dichromic acid alkali metal salts or ammonium salts. Cr ³⁺ is supplied by Cr ³⁺ such as chromium sulfate, chromium nitrate, chromium oxide, etc.
The compound or the solution thereof may be added directly to the treatment liquid, or Cr ⁶⁺ in the treatment liquid may be reduced with a reducing agent. As the reducing agent, known reducing agents such as alcohol, starch, glucose and tannic acid can be used.

The total amount of Cr in the chromate treatment liquid is 1 to 100 g / l
It is. The reason for this is that if the amount is less than 1 g / l, the amount of Cr deposited on the chromate film formed is small and the desired lubricity and corrosion resistance cannot be obtained, and if it exceeds 100 g / l, the effect is saturated, which is uneconomical. This is because the lubricity and corrosion resistance are adversely affected. The weight ratio of Cr ³⁺ / total Cr in the chromate treatment liquid is 0.05 to 0.3. The reason for this is that if the ratio is less than 0.05, the chromate film formation efficiency is low, and not only the desired lubricity and corrosion resistance cannot be obtained, but also the chromium fixation ratio of the generated chromate film is low and chromium elution becomes a problem. This is because the ratio of Cr ⁶⁺ in the chromate film is reduced, the self-repairing effect becomes insufficient, and desired corrosion resistance cannot be obtained.

In the present invention, Co ²⁺ is an essential component for improving the production efficiency of the chromate film and at the same time for adhering the organic resin to the surface of the chromate film, and for improving the lubricity and corrosion resistance. is there. Further, Co ²⁺ has a function of making the appearance of the chromate film after the electrolytic treatment beautiful. The reason is that the Co compound deposited by electrolysis has a stable color tone, so that the entire chromate film has a stable color tone without unevenness.

The supply of Co ²⁺ may be carried out by adding a compound such as cobalt sulfate, cobalt carbonate, cobalt chloride or cobalt nitrate, or may be carried out by dissolving metallic cobalt, cobalt oxide or the like. . The amount of Co ²⁺ in the chromate treatment liquid is 0.1 to 100 g / l. The reason for this is that if it is less than 0.1 g / l, the chromate film formation efficiency is low,
In addition, the amount of organic resin that adheres to the surface of the chromate film is so small that the desired lubricity and corrosion resistance cannot be obtained, and 100 g / l
If it exceeds, not only is it uneconomical because the effect is saturated, but also the lubricity and corrosion resistance are adversely affected.

As for the appearance, if it is less than 0.1 g / l, a beautiful appearance cannot be obtained due to unevenness, and if it exceeds 100 g / l, the appearance is bluish and the original color tone of the chromate film cannot be obtained. The range of 0.1 to 100 g / l is preferred. The chromate treatment liquid of the present invention may further contain Ni ²⁺ . Ni
²⁺ improves lubricity and corrosion resistance by the same action as Co ²⁺ . The supply of Ni ²⁺ may be carried out by adding a compound such as nickel sulfate, nickel carbonate, nickel chloride or nickel nitrate, or may be carried out by dissolving metallic nickel, nickel oxide or the like.

The Ni compound deposited by electrolyzing the chromate treatment liquid containing these Ni ²⁺ does not have the effect of stabilizing the color tone of the chromate film such as the Co compound and providing a beautiful appearance. Therefore, in order to obtain a beautifully-appearing chromate film, it is essential that the chromate treatment liquid contains Co ²⁺ , and the chromate treatment liquid contains Ni ²⁺ in addition to Co ^{2+.
Even when 2+} is contained, a chromate film having a beautiful appearance can be obtained by the action of the Co compound deposited by electrolysis.

The amount of Ni ²⁺ in the chromate treatment liquid is 0.1 to 10
0 g / l, and the total amount of Co ²⁺ and Ni ²⁺ is 0.1 to 100 g / l
Is within the range. The reason for this is that both lower limits are 0.1 g / l.
When the ratio is less than 1, the efficiency of forming the chromate film is low, and the amount of the organic resin adhering to the surface of the chromate film is too small to obtain the desired lubricity and corrosion resistance.
If the amount exceeds 100 g / l, not only is it uneconomical because the effect is saturated, but also the lubricity and corrosion resistance are adversely affected.

In the present invention, SO ₄ ²⁻ has an action of improving the production efficiency of the chromate film and at the same time attaching the organic resin to the surface of the chromate film, and is an essential component for improving the lubricity and corrosion resistance. Is. The supply of SO ₄ ²⁻ is performed by adding sulfuric acid or a sulfate compound such as cobalt sulfate or ammonium sulfate. The amount of SO ₄ ²⁻ in the chromate treatment liquid is 0.1 to 100 g / l. The reason for this is that if it is less than 0.1 g / l, the chromate film formation efficiency is low,
In addition, the amount of organic resin that adheres to the surface of the chromate film is so small that the desired lubricity and corrosion resistance cannot be obtained, and 100 g / l
This is because the effect is saturated when the value exceeds the above range, which is not only uneconomical but also adversely affects lubricity and corrosion resistance due to chemical reactions other than electrolysis.

The SO ₄ ²⁻ / total Cr weight ratio in the chromate treatment liquid is more than 0.1 and 2 or less. The reason for this is that if the ratio is 0.1 or less, the generation efficiency of the chromate film is low, metal Cr is deposited, and the amount of the organic resin adhering to the surface of the chromate film is small, so the desired lubricity and corrosion resistance cannot be obtained.
This is because the effect is saturated when the value exceeds the above range, which is not only uneconomical but also adversely affects lubricity and corrosion resistance due to chemical reactions other than electrolysis.

The weight ratio of SO ₄ ² / / total Cr in the chromate treatment liquid is more preferably 0.2 to 1.5. In the present invention, the water-soluble or water-dispersible organic resin is the most important component for improving lubricity and corrosion resistance. The amount of the water-soluble or water-dispersible organic resin in the chromate treatment liquid in the present invention is 0.1 to 100 g / l.

The chromate treatment liquid to which the organic resin was added in the range of 0.1 to 100 g / l had a high viscosity. By electrolyzing this liquid, the organic resin was not uniformly dispersed in the chromate film and the chromate film It is possible to make most of them exist on the outer surface, and the surface shape becomes uneven. Lubricity is improved by the surface shape having the unevenness and the sliding resistance reducing action of the organic resin itself. Further, the barrier effect of the organic resin attached to the surface of the chromate film and the action of the organic resin retaining the soluble chromium improve the corrosion resistance.

When the amount of the organic resin is less than 0.1 g / l, the viscosity of the treatment liquid is low, and therefore the organic resin does not adhere to the outermost surface of the chromate film and is dispersed in the chromate film, resulting in lubricity and corrosion resistance. The improvement effect of does not appear. Also, if it exceeds 100 g / l, not only is it uneconomical because the effect is saturated,
On the contrary, it adversely affects lubricity and corrosion resistance. Further, since the viscosity of the treatment liquid is too high, problems such as gelation of the treatment liquid and poor appearance of the chromate film occur.

The amount of the water-soluble or water-dispersible organic resin in the chromate treatment liquid is more preferably 20 to 100 g / l. The water-soluble or water-dispersible organic resin used in the present invention is not particularly limited, for example,
Acrylic resin, polyester resin, urethane resin, epoxy resin, polycarboxylic acid resin, polyethylene glycol, other water-soluble or water-dispersible containing hydrophilic groups such as carboxyl group, hydroxyl group, sulfonic acid group, amino group, etc. Organic resins can be mentioned.

As the water-soluble or water-dispersible acrylic resin, one or more selected from acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, acrylamide, methacrylamide, and derivatives thereof are polymerized or All acrylic resins obtained by copolymerization are included. Examples of these acrylic resins include polyacrylic acid, polymethacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, polyacrylamide, acrylic acid ester-methacrylic acid ester copolymer, acrylic acid-acrylic acid ester-methacrylic acid ester. Copolymer, methacrylic acid-acrylic acid ester-
Examples thereof include methacrylic acid ester copolymers, their derivatives, and mixtures thereof.

Examples of the polycarboxylic acid resin used in the present invention include maleic anhydride-olefin copolymers, maleic anhydride-styrene copolymers, and esterified products thereof. These organic resins are required to be water-soluble or water-dispersible in order to stably exist in the treatment liquid, and when a water-dispersible organic resin is used, a surfactant, an emulsifier, a surface A charge adjusting agent, a viscosity adjusting agent, a dispersant and the like can be added if necessary.

The organic resin used in the present invention is more preferably one or more selected from acrylic resins, polyester resins, urethane resins, polycarboxylic acid resins and derivatives thereof. This is because these resins are resins that form a chromate film showing an absorption peak due to C = O stretching vibration at 1750 to 1720 cm ^-1 in the FT-IR analysis described in the first invention of the present invention, so that the lubricity is improved. Because it is excellent in.

The organic resin used in the present invention is more preferably one of acrylic acid ester and methacrylic acid ester.
Acrylic resin obtained by polymerizing or copolymerizing one or more kinds, or one or more kinds of acrylic acid ester and methacrylic acid ester as an essential monomer, and acrylic acid, methacrylic acid, acrylamide, methacrylamide And an acrylic resin obtained by copolymerizing one or more selected from these derivatives, or a mixture of these acrylic resins.

This is because these resins are the same as the above-mentioned FT-IR.
This is because it is a resin that forms a chromate film that exhibits an absorption peak due to C = O stretching vibration at 1750 to 1720 cm ^-1 in the analysis, and therefore has excellent lubricity, and at the same time, it has excellent lubricity and corrosion resistance due to the properties inherent to acrylic resins. . The pH of the chromate treatment liquid in the present invention is in the range of 1-5. The reason for this is that if it is less than 1, not only does the chromate film form due to chemical reactions other than electrolysis, making it difficult to control the amount of adhesion, but also the chromate film and the organic resin on the surface are redissolved after the cathodic electrolysis treatment, resulting in poor lubricity and corrosion resistance. This is because the adverse effect is exerted, and when it exceeds 5, the stability of the treatment liquid is lowered to generate a precipitate, and the generation efficiency of the chromate film and the adhesion efficiency of the organic resin are also reduced. The pH can be adjusted by adding sulfuric acid, alkali metal hydroxide or the like.

The temperature of the chromate treatment liquid is 20 to 70 ° C. The reason for this is that if the temperature is lower than 20 ° C, the undissolved substance precipitates in the treatment liquid, and the electrical conductivity also decreases, and if the temperature exceeds 70 ° C, the amount of water vapor in the treatment liquid is large and the components of the treatment liquid This is because it becomes difficult to control the concentration of. Chromate treatment in the present invention, the current density is 1 ~ 50 A / dm ² , 0.5 ~ 10
It is performed by subjecting a zinc-based plated steel sheet to cathodic electrolysis with an electric quantity of 0 C / dm ² . The reason for this is that when the current density is less than 1 A / dm ² or more than 50 A / dm ² , the chromate film formation efficiency and the organic resin adhesion efficiency are significantly reduced. Moreover, the chromate film when the electrical quantity surface desired lubricity not sufficiently cover the chromate film and the organic resin is a zinc-based plated steel sheet is less than 0.5 C / dm ^2, no corrosion resistance is obtained, greater than 100C / dm ² This is because not only is the film formed excessively thick and the external appearance deteriorates, but the lubricity and corrosion resistance are adversely affected.

The chromate-treating solution is preferably 1
Contains ~ 300 g / l silica. In the present invention, silica has a function of further improving lubricity and corrosion resistance.
The silica is supplied by adding colloidal silica, vapor phase silica or the like to the treatment liquid. The amount of silica is 1g /
If it is less than l, the effect of improving lubricity and corrosion resistance is not exhibited, and
When it exceeds 0 g / l, not only the stability of the treatment liquid is deteriorated, but also the lubricity and corrosion resistance are adversely affected.

The chromate-treating solution preferably further has a concentration of 0.
01 containing the PO ₄ ^3- of 10g / l. In the present invention, PO ₄
^3- has the effect of further improving lubricity and corrosion resistance. PO ₄ ^3- supply is performed by adding phosphoric acid, a phosphate compound, such as the first sodium phosphate to the treatment liquid. The PO ₄ ^3- amount is less than 0.01 g / l of lubricity, without corrosion resistance improvement effect of the expression, exceeds 10 g / l, not only the stability of the processing solution is lowered, rather lubricity, corrosion resistance Adversely affect.

[0082]

EXAMPLES Hereinafter, the present invention will be specifically described based on examples.
I will tell. (Example 1) For a cold rolled steel plate (SPCC) having a plate thickness of 0.7 mm
Adhesion amount of 20 g / m by known method ²Electrogalvanizing
After washing, rinsing with water, and drying, various sets can be prepared by electrolytic chromating.
The formed chromate film was formed.

The bath of the chromate treatment solution contains anhydrous chromium.
Acid, 40% chromium (III) sulfate solution, cobalt sulfate,
Nickel sulfate, organic resin shown in Table 1, colloidal silica
(Nissan Chemical Co., Ltd. ST-40), 1st sodium phosphate
Cr using Cr⁶⁺, Cr ³⁺, Co²⁺, Ni²⁺, SO
_Four ^2-, Organic resin, silica, PO_Four ^3-Is in the following range
The treatment liquid was prepared as described above.

The treatment solution had a pH of 3, a temperature of 50 ° C., a current density of 10 A / dm ² , and an electric quantity of 0.5 to 100 C / dm ² .
Cathodic electrolysis was performed under the condition of ² . In addition, when manufacturing the steel plate of a comparative example, the electrolytic treatment was performed with a bath composition and an electrolysis condition outside these ranges. [Chromate treatment liquid composition] Cr ⁶⁺ + Cr ³⁺ : 1 to 100 g / l Cr ³⁺ / (Cr ⁶⁺ + Cr ³⁺ ): 0.05 to 0.3 Co ²⁺ : 0.1 to 100 g / l Ni ²⁺ : No addition or 0.1 to 100 g / l SO ₄ ²⁻ : 0.1 to 100 g / l SO ₄ ²⁻ / (Cr ⁶⁺ + Cr ³⁺ ): 0.11 to 2 Organic resin: 0.1 ˜100 g / l Silica: no addition or 1 to 300 g / l PO ₄ ³⁻ : no addition or 0.01 to 10 g / l Table 2 shows the composition and lubricity of the obtained chromate film,
The corrosion resistance test results and the appearance determination results are shown. In addition,
Lubricity and corrosion resistance test methods and appearance determination methods are as follows.

[Lubricity and Corrosion Resistance Test Method, Appearance Judgment Method] Lubricity was judged by measuring friction resistance by a plane sliding test. That is, an oil-free sample with chromate treatment on both sides was pressed with a pressing load (F) of 50 kgf using a flat indenter (contact length 10 mm), and the drawing speed was 500 mm / min.
The average pulling load (P) when pulled out by 50 mm was measured, and the friction coefficient μ (P / 2F) was calculated. The criteria are as follows.

⊚: μ <0.15 ◯: 0.15 ≦ μ <0.2 Δ: 0.2 ≦ μ <0.3 ×: 0.3 ≦ μ Corrosion resistance was measured by salt spray test (JIS Z2371) 200.
The appearance was evaluated after a lapse of time.

⊚: No white rust occurred ○: White rust occurrence area ratio <5% △: 5% ≦ White rust occurrence area ratio <30% ×: 30% ≦ White rust occurrence area ratio Appearance with or without color tone and unevenness It was visually determined by.

◯: Good appearance Δ: Somewhat poor appearance ×: Poor appearance

[0089]

[Table 1]

[0090]

[Table 2]

[0091]

[Table 3]

[0092]

[Table 4]

[0093]

[Table 5]

[0094]

[Table 6]

[0095]

[Table 7]

[0096]

[Table 8]

As is clear from Table 2, the chromate-treated zinc-based plated steel sheet of the present invention has excellent lubricity and corrosion resistance, and has a beautiful appearance. (Example 2) A cold-rolled steel plate (SPCC) having a plate thickness of 0.7 mm was electrogalvanized by a known method at an adhesion amount of 20 g / m ² . After washing with water and drying, a chromate film is formed on this electrogalvanized steel sheet by subjecting it to cathodic electrolysis with various bath compositions, pH, and temperature using chromate treatment liquids with varying current densities and amounts of electricity. did.

Reagents used for the bath of chromate treatment liquid
Is Cr⁶⁺Chromic anhydride or sodium dichromate as the source
Uses Cr, Cr³⁺40% chromium (III) sulfate solution
Or add the reducing agent isopropyl alcohol.
Cr by adding call ⁶⁺To reduce Cr³⁺age
Was. Co²⁺As a source, cobalt sulfate or cobalt chloride
Using. Ni²⁺Nickel sulfate or nickel chloride as a source
Was used. SO_Four ^2-Sulfuric acid or cobalt sulfate as a source
Was used. As the organic resin, the organic resin shown in Table 1 is used.
Resin was used.

As silica, colloidal silica (ST-40 manufactured by Nissan Chemical Industries, Ltd.) or vapor phase silica (AEROSIL200 manufactured by Nippon Aerosil Co., Ltd.) was used. The PO ₄ ^3- source using phosphoric acid or the monosodium phosphate. In Table 3,
The bath composition, pH, temperature of the chromate treatment liquid and the current density and quantity of electricity in the cathodic electrolysis treatment are shown.

Further, the lubricity of the obtained chromate film,
Table 3 also shows the results of the corrosion resistance test and the results of determining the appearance of the chromate film. The lubricity and corrosion resistance test methods and the appearance determination method were the same as in Example 1.

[0101]

[Table 9]

[0102]

[Table 10]

[0103]

[Table 11]

As is clear from Table 3, all the chromate-treated zinc-based plated steel sheets produced by the method of the present invention have excellent lubricity and corrosion resistance, and have a beautiful appearance.

[0105]

As described above, the chromate-treated zinc-based plated steel sheet of the present invention is excellent in lubricity, corrosion resistance and appearance, and according to the production method of the present invention, A chromate-treated zinc-based plated steel sheet having excellent properties, corrosion resistance, and appearance can be produced by a low-cost method that is excellent in the stability of a treatment liquid, and the present invention is industrially extremely valuable.

[Brief description of drawings]

FIG. 1 shows the surface of a chromate film of the present invention, which is obtained by FT-IR
3 is a graph showing a spectrum measured by using a reflection method.

FIG. 2 is a graph showing the relationship between the sputtering time of the chromate film of the present invention and the AES electron spectrum intensity of each element.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuo Totsuka, No. 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture, Technical Research Institute, Kawasaki Steel Co., Ltd. (72) Nobuyuki Morito No. 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Kawasaki Steel Corporation Technical Research Center

Claims (16)

[Claims] 1. A chromate-treated zinc-based plated steel sheet comprising a zinc or zinc alloy plated layer formed on at least one surface of a steel sheet and a chromate film formed on the zinc or zinc alloy plated layer, wherein the chromate film is (a) metal. 5 to 200 mg / m ² of one surface of the steel sheet in terms of Cr, selected from Cr oxides, Cr hydroxides and hydrates thereof.
1 or 2 or more, (b) 1 to 1000 mg / m ² of metallic Co or Co compound per steel plate in terms of metallic Co conversion
Type or two or more types, (c) 0.1-10 per one side of steel plate
A chromate-treated zinc-based plated steel sheet excellent in lubricity and corrosion resistance, which is composed of an organic resin of 00 mg / m ² and has no metal Cr in the chromate film. 2. The chromate film is subjected to FT-IR analysis by a reflection method on its surface, which is 1750 to 172.
The chromate-treated zinc-based plated steel sheet according to claim 1, which is a chromate film having an absorption peak due to C = O stretching vibration at 0 cm ^-1 . 3. The chromate treatment according to claim 1, wherein the organic resin is one or more selected from acrylic resins, polyester resins, urethane resins, polycarboxylic acid resins and derivatives thereof. Zinc-based plated steel sheet. 4. The chromate-treated zinc-based plated steel sheet according to claim 1, wherein the organic resin is a water-soluble or water-dispersible acrylic resin. 5. An acrylic resin obtained by polymerizing or copolymerizing one or more kinds of acrylic acid ester and methacrylic acid ester, or one or two kinds of acrylic acid ester and methacrylic acid ester as an organic resin. An acrylic resin obtained by copolymerizing these with one or more selected from acrylic acid, methacrylic acid, acrylamide, methacrylamide, and derivatives thereof, using the above as essential monomers, or a mixture of the above acrylic resins. The chromate-treated zinc-based plated steel sheet according to any one of claims 1 to 4. 6. A chromate-treated zinc-based plated steel sheet comprising a zinc or zinc alloy plated layer formed on at least one surface of a steel sheet and a chromate film formed on the zinc or zinc alloy plated layer, wherein the chromate film is a metal (a). 5 to 200 mg / m ² of one surface of the steel sheet in terms of Cr, selected from Cr oxides, Cr hydroxides and hydrates thereof.
1 or 2 or more, (b) 1 to 1000 mg / m ² of metallic Co or Co compound per steel plate in terms of metallic Co conversion
Type or two or more types, (c) 0.1-10 per one side of steel plate
00 mg / m ² of organic resin, wherein the organic resin is one of acrylic acid ester and methacrylic acid ester.
Acrylic resin obtained by polymerizing or copolymerizing one or more kinds, or one or more kinds of acrylic acid ester and methacrylic acid ester as an essential monomer, and acrylic acid, methacrylic acid, acrylamide, methacrylamide And a chromate-treated zinc-based resin excellent in lubricity and corrosion resistance, which is an acrylic resin obtained by copolymerizing one or more selected from these derivatives, or a mixture of the acrylic resins. Plated steel sheet. 7. The chromate-treated zinc-based plated steel sheet according to claim 1, wherein the content of the organic resin in the chromate film is highest on the outermost surface of the chromate film. 8. The chromate film further contains 1 to 1000 mg / m ² of silica per one side of the steel sheet.
7. The chromate-treated zinc-based plated steel sheet according to any of 7. 9. The chromate film further contains 0.01 to 50 mg / m ² of P per one side of the steel sheet.
Chromate-treated zinc-based plated steel sheet according to any one of the above. 10. The chromate film further comprises 1 to 1000 mg / m ² of metallic Ni per one side of the steel sheet in terms of metallic Ni,
Contains one or more Ni compounds and contains metal C
The chromate-treated zinc-based plated steel sheet according to any one of claims 1 to 9, wherein the total of the O content-equivalent Co content and the metal Ni-equivalent Ni content is 1 to 1000 mg / m ² per one side of the steel sheet. 11. A chromate film is formed by subjecting a zinc-based plated steel sheet having a zinc or zinc alloy plating layer formed on at least one surface of the steel sheet to cathodic electrolytic treatment in a chromate treatment solution. ,
In the method for producing a chromate-treated zinc-based plated steel sheet,
As the chromate treatment liquid, (a) the total Cr amount is 1 to 100 g / l
And the Cr ³⁺ / total Cr weight ratio is 0.05 to 0.3
Cr ⁶⁺ and Cr ³⁺ , (b) 0.1-100 g / l Co ²⁺ , (c) total SO ₄
^2- amount is 0.1 to 100 g / l, and SO ₄ ^2- / total Cr weight ratio is more than 0.1 and 2 or less SO ₄ ^2- , (d) 0.1 to 100 g
/ l water-soluble or water-dispersible organic resin, containing, pH
Is in the range of 1 to 5, the temperature is 20 to 70 ° C., the current density is 1 to 50 A / dm ² , and the electrical quantity of 0.5 to 100 C / dm ² is applied to the galvanized steel sheet. A method for producing a chromate-treated zinc-based plated steel sheet, which comprises forming a chromate film by performing a cathodic electrolysis treatment. 12. A water-soluble or water-dispersible organic resin,
The method for producing a chromate-treated zinc-plated steel sheet according to claim 11, which is one or more selected from acrylic resins, polyester resins, urethane resins, polycarboxylic acid resins and derivatives thereof. 13. A water-soluble or water-dispersible organic resin,
Acrylic resin obtained by polymerizing or copolymerizing one or more kinds of acrylic acid ester and methacrylic acid ester, or acrylic resin and acrylic resin using one or more kinds of acrylic acid ester and methacrylic acid ester as essential monomers. The chromate treatment according to claim 11, which is an acrylic resin obtained by copolymerizing one or more selected from acids, methacrylic acid, acrylamide, methacrylamide, and derivatives thereof, or a mixture of the acrylic resins. Manufacturing method of zinc-based plated steel sheet. 14. The chromate treatment liquid further comprises 1 to 300 g.
The method for producing a chromate-treated zinc-based plated steel sheet according to any one of claims 11 to 13, containing / l of silica. 15. The chromate treatment liquid further comprises 0.01-10.
method for producing a chromate-treated zinc-based plated steel sheet according to any one of claims 11 to 14 containing PO ₄ ^3- of g / l. 16. The chromate treatment liquid further comprises 0.1 to 10
It contains 0 g / l Ni ²⁺ and the total amount of Co ²⁺ and Ni ²⁺ is 0.1.
The method for producing a chromate-treated zinc-based plated steel sheet according to any one of claims 11 to 15, wherein the method is -100 g / l.