JP3132979B2 - Galvanized steel sheet with excellent lubricity, chemical conversion properties and adhesive compatibility - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to lubricity, chemical conversion treatment,
The present invention relates to a galvanized steel sheet having excellent adhesive compatibility.

[0002]

2. Description of the Related Art Mn-
JP-A-3-249182 discloses that a non-crystalline oxide of P is formed to obtain a steel sheet having excellent pressability and chemical conversion treatment properties.
No. 6,086,045. Such a surface-treated steel sheet has improved slidability in press forming more than a steel sheet, and can uniformly generate a chemical conversion treatment such as a bond treatment.
It is a plated steel sheet that has excellent functions such as uniform coating.

[0003]

When the above-mentioned inorganic oxide is formed on a galvanized steel sheet, the pressability and the chemical conversion property are improved, but it is used for omitting or reinforcing welding in automobiles and home appliances. There is a problem such as lowering the adhesive strength of the existing adhesive. The method of the present invention has been made to solve such problems advantageously, and has an object to provide a galvanized steel sheet excellent in lubricity, chemical conversion property, and adhesive compatibility as described above. Things.

[0004]

Means for Solving the Problems] It is a feature of the present invention, 1 the Mn-Zn-OH-PO ₄ oxide on the plating layer surface as 0.1 -100 mg / m ² and the amount of P as a Mn amount -100 mg / This is a galvanized steel sheet excellent in lubricity, chemical conversion property and adhesive compatibility, characterized in that m ^{2 is} generated and the P / Mn ratio is set to 0.3 to 50.

[0005]

The present inventors have investigated the cause of such a decrease in adhesive strength in detail, and as a result, it has been confirmed that the adhesive is peeled off within the inorganic oxide layer. Further studies revealed that the peeled surface was P-rich. It was presumed that this P layer peeled finely during processing such as pressing, and that lubricity was obtained by the rolling function. On the contrary, it is considered that a peeled surface is formed. The present inventors have proposed to avoid such contradictory functions by controlling P / Mn in the inorganic oxide based on the above findings, thereby improving lubricity and improving adhesive strength (adhesion). It was developed to improve. As a zinc-based plated steel sheet that generates an inorganic oxide as described above,
For example, hot-dip plating, electroplating, vapor deposition plating,
There are various production methods such as thermal spraying, and the plating composition is not only pure Zn but also Zn and Fe, Zn and Ni, and Z
n and Al, Zn and Mn, Zn and Cr, Zn and Ti, Zn
Fe, Ni, Co, Al, Pb, S as a main component containing Zn such as Mg and Mg or for improving various functions such as corrosion resistance.
including one or more alloying elements and impurity elements such as n, Sb, Cu, Ti, Si, B, P, N, S, and O;
Also, ceramic fine particles such as SiO ₂ and Al ₂ O ₃ , T
Oxides such as iO ₂ , BaCrO _4, and organic polymers such as acrylic resin are dispersed in the plating layer. The composition changes in a single composition in the thickness direction of the plating layer, or continuously or in a layered manner. In addition, in the case of a multilayer plated steel sheet, the uppermost layer has a plating composition other than pure Zn, Zn and Fe, Zn and Ni, Zn and Al, Zn and Mn, Zn and C
r, Zn and Ti, Zn and Mg such as Mg as main components,
In order to improve various functions such as corrosion resistance, it contains one or more alloying elements and impurity elements, and contains SiO ₂ , Al ₂
Ceramic particles such as O ₃ , TiO ₂ , BaCrO
An oxide such as ₄ and an organic polymer such as an acrylic resin are dispersed in a plating layer. Furthermore, even in the case of a multi-layer plated steel sheet that is plated with zinc as a main component as described above on a surface of a coated steel sheet that does not contain zinc or that does not contain zinc as in the case of an aluminum-plated steel sheet, the surface also contains zinc as a main component. If it is, the effects such as pressability and chemical conversion treatment will not be changed.

For example, hot-dip galvanized steel sheet, vapor-deposited galvanized steel sheet, iron-zinc alloyed hot-dip galvanized steel sheet, galvanized steel sheet mainly containing zinc and aluminum, iron, etc. Alloyed hot-dip galvanized steel sheet (generally called half-alloy),
One-sided-zinc alloyed hot-dip galvanized layer, other side hot-dip galvanized layer, galvanized steel sheet, metal containing zinc or zinc as a main component, and iron or nickel on these plated layers by electroplating, vapor deposition plating, etc. Or electrogalvanized steel sheets, electroplated steel sheets of alloys such as zinc, nickel, and chromium, as well as electroplated steel sheets of a single alloy layer or multilayer alloys, and vapor-deposited steel sheets of zinc and zinc-containing metals. In addition, there is a dispersion plated steel sheet in which ceramic fine particles such as SiO ₂ and Al ₂ O ₃ , TiO ₂ oxide fine particles, and organic polymer are dispersed in zinc or zinc alloy plating.

[0007] The above such as, as a Mn-Zn-OH-PO ₄ based oxide to produce the plating layer surface of the galvanized steel sheet,
For example, Mn metal oxide in the oxide mainly functions to prevent the adhesion of the plating metal to the mold during press molding, and when sliding during press molding, as an oxide having a Korugari lubrication function with a lubrication function It is considered that a structure in which an oxygen acid composed of P is bonded to the above crystalline structure via an oxygen bond mainly functions. However, since the film-forming reaction precipitates completely from the aqueous solution by utilizing the pH rise at the interface, the function of the film cannot be strictly selected. It can be understood that a part performs the roller lubrication function. The constituent components of the oxide are all inorganic substances, do not apply a load to the degreasing solution after pressing, and dissolve by a decrease in pH during the chemical conversion treatment, so that the chemical conversion film can be formed normally. These film forming components are also components contained in the chemical conversion treatment solution and do not contaminate the chemical conversion treatment solution.

[0008] The method for producing an oxide is as follows: a zinc-based plated steel sheet is immersed in an acidic aqueous solution containing an oxide component having an anti-adhesion function and an oxide component having a rolling lubrication function, or is subjected to cathodic electrolytic treatment. A film can be formed reliably. In the immersion treatment, when Zn dissolves,
H rises, and as a result, the film components are precipitated as hydroxides or oxides. Dissolved Zn and other plating layer components can also utilize an oxidation-reduction reaction mixed into the film. Dissolution of Zn is an oxidation reaction, and correspondingly, oxidized metal ions are precipitated as insoluble reduced oxides. Cathodic electrolysis treatment that can be deposited has the effect of promoting an increase in pH at the interface. The interfacial reaction can also be controlled by adjusting the thickness of the water film such as a spray treatment or a coating treatment.

[0009] oxidation amount with the adhesion-preventing function of the zinc-based plated steel sheet, Mn is obtained sufficiently effective in a small amount and 0.1-100 mg / m ² as metal, clear lubrication is less than 0.1 mg / m ² The effect is not recognizable. Even if it exceeds 100 mg / m ² , the effect does not change and is economically disadvantageous. Regarding the amount of the oxide having a rolling lubrication function, a reliable lubrication function can be obtained when P is 1 to 100 mg / m ² as an element, and a sufficient lubrication effect cannot be obtained if the P amount is less than 1 mg / m ² , and 100 mg / m 2 Even if it exceeds ^{2, the} effect does not change and it is economically disadvantageous. Mn-Zn-PO ₄ -OH oxide,
Although the structure is not clear, it is presumed to be an amorphous film. However, to improve the adhesiveness, the P / Mn ratio is determined by the P / Mn ratio.
The effect is an adhesive strength equal to or higher than that of a conventional steel sheet. In particular, when the P / Mn ratio is 0.3 to 30, the adhesive strength is much higher than that of the conventional steel sheet. If it is less than 0.3, the lubricating effect cannot be sufficiently exerted with a small amount, and if it exceeds 50, the adhesive compatibility is reduced. The lower the P / Mn ratio, that is, the higher the Mn ratio in the film, the higher the adhesive strength. However, this is because the Mn oxide-based (oxide, hydroxide, etc.) film has a high bonding force with the adhesive and the plating layer, and the film itself has a high strength, and further destruction. It can be estimated that it is hard to be done. Further, it is considered that this suppresses the propagation of cracks in the layer when the adhesive is peeled off. Such an oxide is generally formed as a mixed film when it is deposited by a chemical reaction at the interface as in an immersion method or a cathodic electrolytic treatment method. However, the anti-adhesion function is stronger at the interface with the galvanization, and the anti-rolling lubrication function is stronger at the surface of the film, so that the film can be formed with a gradient function.
Thus, when a high surface pressure is applied to a local part of a galvanized steel sheet as in the case of pressing a difficult-to-form part, there is an effect that the critical surface pressure at which galling occurs is improved.
Since a so-called press forming load range can be widely used, practically, the design of the mold is facilitated, and the press work is also stabilized, so that great benefits can be enjoyed.

The method of forming the functionally graded film utilizes the difference in solubility products of metal oxides and the like to obtain the ion concentration of each component,
It consists of controlling the ion concentration at the interface by adjusting the flow rate, the dissolution temperature, and the current density in the case of electrolytic treatment. For example, in the case of Mn and P-based oxides, potassium permanganate, phosphoric acid, and sulfuric acid are added to the treatment solution to cause reaction with the zinc-based plated steel sheet, thereby dissolving Zn and reducing permanganate ions. As a result, a film mainly composed of Mn oxide or hydroxide is formed due to a rapid increase in PH at the interface, and the increased PH is reduced by the formation of the film, hydrolysis of the formed film occurs, and phosphoric acid having lower solubility is formed. It becomes salt and reforms the film. It is considered that this repetition occurs within a short time, P is rich in the surface layer, and Mn is a gradient function rich in the lower layer.

[0011] Next, Mn-Zn-OH-PO ₄ system Mn in the oxide,
P-based oxides can be analyzed, but it is impossible to analyze the abundance of Zn and OH when oxides are formed. P / Mn ratio of 0.3 to 50
As described above, the shearing effect of the oxide (film) is improved as described above, and cracks are less likely to occur in press molding.
Further, even if a crack occurs, the propagation of the crack can be substantially prevented, so that the adhesiveness of the adhesive (adhesive compatibility) is excellent.

The elements which do not impair the lubricity, chemical conversion property and adhesive compatibility (adhesion) even if mixed into the film and which are essentially unchanged include Li, Be, C, F, and Na, Mg,
Al, Si, Cl, K, Ca, Ni, Mo, V, W, Ti, Fe, Rb, S
r, Y, Zn, Nb, Cs, Ba, lanthanide ions and oxides, hydroxides, phosphates, sulfate nitrates, etc. to some extent (less than about 10% in the coating) have no effect . Furthermore, if the amounts of Cr, Cd, Pb, Sn, and As are very small, they do not affect the chemical conversion property or the contamination of the chemical conversion solution, and the effect of the present invention is not changed.

The method for producing the Mn and P-based crystalline oxides described above includes, for example, a potassium permanganate concentration:
0.5 to 50 g / l, potassium monophosphate 0.5 to 100
g / l, phosphoric acid: 0 to 30 g / l, sulfuric acid: 0 to 10 g /
1 for contact such as dipping and coating, or current density of 5 to 60 A /
It can be produced by electrolysis at dm ² . If necessary, a pretreatment may be performed with an alkali or an acid, a brush, or the like before generating the inorganic oxide.

[0014]

Next, examples of the method of the present invention will be described together with comparative examples.

[Table 1]

Note 1) Galvanized steel sheet EG: Electro-galvanized steel sheet, AS: Alloyed hot-dip galvanized steel sheet (Fe 10%, Al 0.2%, remaining Zn), GI: Hot-dip galvanized steel sheet, HA: Semi-alloyed hot-dip zinc Coated steel sheet (Fe
5%, Al 0.3%, residual Zn), Zn-Ni: zinc-nickel alloy electroplated steel sheet (Ni 9%, residual Zn), Zn
-Mg: zinc-magnesium alloy vapor-deposited plated steel sheet (Mg1
0%, residual Zn), Zn-Cr: Zn-Cr alloy electroplated steel sheet (Cr 14%, residual Zn), Zn-Mn: Zn-M
n alloy electroplated steel sheet (Mn 20%, residual Zn), Zn-
Al: hot-dip galvanized aluminum alloy steel sheet (Al5
%, Mg 0.1%, residual Zn), Zn / Al-Zn: zinc upper layer aluminum zinc alloy hot-dip coated steel sheet (upper layer Zn2
g / m ^2, the lower layer Al55%, residual Zn60g / m ^2), Z
n-Fe: zinc-iron alloy electroplated steel sheet (Zn 85%,
Fe 15%), Zn-Cr-Ni: Zn-Cr-Ni alloy electroplated steel sheet (Zn 85%, Cr 13%, Ni2
%), Zn / Al: zinc upper layer aluminum-plated steel sheet (upper layer Zn 1 g / m ² , lower layer Al 60 g / m ² ). All steel plates are 0.8mm thick . Note 2) Pretreatment Activation method A: 1% plating steel sheet in 5% H ₂ SO ₄ solution
Soak for 10 seconds. Activation method B: Electrolysis of 5 to 10 Adm ² was performed in a 5% NaOH solution using a plated steel sheet as a cathode. Activation Method C: A roll having a diameter of 0.5 mm and a hair length of 20 mm (made of stainless steel) having a diameter of 300 mm was formed, and the surface of the steel plate was rotated at a contact pressure of 10 kg to activate the surface. Note 3) Method for producing inorganic oxides Potassium permanganate: 0.5 to 50 g / l, phosphoric acid 1
Potassium 0.5-100 g / l, phosphoric acid 0-30 g /
1, sulfuric acid 0 to 10 g / l solution was prepared. Immersion: The coated steel sheet was immersed for 1 to 60 seconds and then washed and dried. Coating: Sprayed onto a plated steel sheet by spraying, adjusted the water film with a roll, and dried. Electrolysis: A plated steel sheet was used as a cathode in the solution, and a current density of 5 to 60 A / dm ² was generated, followed by washing with water and drying.
The impurity element was added as a carbonate or the like. Note 4) Pressability Sample size: 17 mm x 300 mm, Tensile speed: 50
0 mm / min, square beat shoulder R: 1.0 / 3.0 mm, sliding length: 200 mm, oiling: Knoxlast 530F40 (manufactured by Parker Kosan Co., Ltd.) 40.1 g / m ^{2 under} a condition of surface pressure of 100 A few points test was conducted between 〜600 kgf, the pulling load was measured, and the friction coefficient was determined from the surface pressure and the slope of the pulling load. Note 5) Chemical conversion property SD5000 (manufactured by Nippon Paint Co., Ltd.) was used as the chemical conversion solution, and after the degreasing and surface conditioning were performed as prescribed, the chemical conversion treatment was performed. The chemical conversion treatment film was judged by SEM (secondary electron beam image) as follows: も の if the film was uniformly formed, △ if the film was partially formed, and partially not formed. Those were judged as x. Note 6) Adhesive compatibility A plated steel sheet is made into a strip with a width of 25 mm, and rust-preventive oil (Knoxlast 530F40, manufactured by Parker Kosan Co., Ltd.)
g / m ² , an epoxy-based adhesive (EP190, manufactured by Cemedine Co., Ltd., hemming adhesive) was applied to the wrap for 8 m.
m, adhesive thickness 0.15mm, three layers adhered, 17
After baking and hardening at 0 ° C. for 20 minutes, the shearing peeling force was determined with a tensile tester, and the shearing force (kgf / cm ² ) on one side was calculated.

[0016]

According to the present invention, it is possible to improve the lubricity and chemical conversion treatment properties of a zinc-based plated steel sheet in which Mn and P-based oxides have been formed, and also to improve the compatibility with an adhesive. Can be expanded. In addition, there is no contamination of the chemical conversion treatment liquid, and not only the productivity is improved in a series of steps of press-adhesion-chemical conversion treatment, but also there is no deterioration of the chemical conversion treatment liquid, and excellent effects such as cost reduction by reducing wastewater treatment can be obtained. can get.

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Claims (1)

(57) [Claims] 1. A 1 as 0.1 -100 mg / m ² and the amount of P the Mn-Zn-OH-PO ₄ oxide as the amount of Mn in the plating layer surface -100 mg /
m ² yielding, lubricity, chemical conversion treatability, good galvanized steel sheet on the adhesive compatibility, characterized in that the P / Mn ratio from 0.3 to 50.