JPH07166369A - Al based and zn-al based plated steel sheet having surface layer excellent in adhesion - Google Patents

Abstract

PURPOSE:To develop an Al based and Zn-Al based alloy plated steel sheet having a surface layer excellent in adhesion by forming a layer contg. Al oxide and Al hydroxide by the equal quantity as the same or above on the surface of a steel sheet plated with Al based and Zn-Al based metal. CONSTITUTION:An Al based plated steel sheet plated with Al or an Al alloy of Al and Si, Mn, Zn or the like or a steel sheet obtd. by immersing a steel sheet into a Zn-55wt.% Al bath and plating the surface with a Zn-Al based alloy is immersed into water or is treated in steam to form a mixed layer enough in Al2O3 and Al (OH)3 by the equal quantity as the same or above on the surface of the plated film into 1nm thickness. This surface layer contains Al (OH)3 by >=0.1 molar ratio to compounds such as Al oxide, phosphate, borate and silicate and heavy metal oxysalt, and the Al plated steel sheet in which the intensity ratio of the oxygen spectrum of XPS showing an Al-OH bond to the intensity of the oxygen spectrum of XPS showing an Al-O bond is regulated to >=1 and excellent in adhesion can be obtd.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aluminum (Al) -based plated steel sheet and a zinc (Zn) -aluminum (Al) -based plated steel sheet having a surface layer having excellent adhesiveness.

[0002]

2. Description of the Related Art Al-based plated steel sheets and Zn-Al-based plated steel sheets have been evaluated for their excellent corrosion resistance and have been widely used for automobiles, home appliances, outdoor equipment, building materials and the like. Further, when it is used as a material for automobiles, higher corrosion resistance is required. Therefore, various alloy-plated steel sheets, resin-coated steel sheets and the like have been developed. These plated steel sheets and resin-coated steel sheets are incorporated into products through various processes such as processing, forming, and joining, but since spot weldability is not always sufficient, they are joined using an adhesive in the joining process. The application of adhesive bonding is being considered. Compared with the case of using welded joint, this adhesive joint has the advantages that the product can be made lighter in weight, has excellent rigidity, and that different materials can be easily joined together. It is considered that one of the characteristics required for a steel sheet is that it has excellent adhesive bondability.

Al-based plated steel sheets and Zn-Al-based plated steel sheets are generally manufactured industrially by a hot dip plating method or an electroplating method, but have a higher adhesiveness than cold-rolled steel sheets which are not plated. It has the disadvantage of being inferior.

In order to improve adhesiveness or bondability,
Usually, the surface of the adherend (substrate) is pretreated. That is, a method of removing oils and fats that adhere to the substrate surface and inhibit good adhesion with a degreasing solvent, a degreasing agent, etc., or remove surface products such as a passive film that deteriorates adhesion with mechanical polishing. Is commonly practiced. In addition, a method of modifying the surface of the substrate by performing a chemical pretreatment such as an alkali treatment or a chemical conversion treatment in order to improve the adhesiveness is generally performed.

For example, in Japanese Unexamined Patent Publication No. 4-350195, zinc (Zn) and iron (Fe) on the surface of an Al or Al alloy substrate, or together with these, silicon (Si) oxide, Al oxide and Al
A method for producing a material having excellent adhesiveness, coating film adhesion, etc. by forming a plating layer containing at least one selected from the group consisting of hydroxides and further subjecting this to a chemical conversion treatment is disclosed. .

As a surface treatment technique for a metal material using an alkaline solution, an Al or Al alloy bonding wire is treated in an alkaline aqueous solution having a pH of 10 to 13 to remove oil content and Al hydroxide on the surface of the wire. Method (JP-A-63-22)
9833), acid (sulfuric acid, hydrochloric acid, etc.), alkali (caustic soda, sodium silicate, sodium phosphate, etc.), solvent, etc. to remove the residual oil and fat on the surface. A plate material for conductive parts of electronic and electrical equipment made of Al alloy (JP-A-3-270061), and a method of electrolytically reducing a roughened metal surface with an alkaline solution (JP-A-4-180598).
Japanese Patent Laid-Open No. 4-289074), a method of colliding an alkaline aqueous solution containing fine particles with the bonding surface of an Al alloy metal fitting that is bonded to rubber has been proposed.

However, the above-mentioned prior art is not intended to improve the adhesiveness by changing the surface condition of the material to be adhered, but rather to smooth the surface of the material and remove the oil and fat components on the surface.

All of the above examples are directed to materials that have not been subjected to plating treatment, and techniques for improving the adhesiveness of plated steel sheets have not been disclosed so far.

[0009]

DISCLOSURE OF THE INVENTION The present invention is directed to Al-based plated steel sheets and Zn-Al-based plated steel sheets, and has an adhesive bondability which is a highly required characteristic as an anticorrosive steel sheet for automobiles. Al-based and Zn-Al with excellent corrosion resistance
The object of the present invention is to provide a system-plated steel sheet.

[0010]

Means for Solving the Problems As a result of repeated studies to solve the above-mentioned problems, the present inventors dip an Al-based plated steel sheet or a Zn-Al-based plated steel sheet in water or treat it in steam. Then, a layer rich in Al oxide and the same amount or more of Al hydroxide on the surface (Al hydroxide and Al
Adhesiveness, by producing a mixed layer of oxides)
In particular, it has been found that it is possible to obtain a material having excellent adhesiveness with a soft synthetic rubber adhesive.

The present invention was made on the basis of the above findings, and the gist of the present invention is that "in the surface layer portion, the molar ratio of Al hydroxide to surface compounds other than Al hydroxide is 0.1 or more, and the thickness is A surface layer having a thickness of 1 nm or more is formed, and the ratio of the spectrum intensity of oxygen of XPS showing Al-OH bond to the spectrum intensity of oxygen of XPS showing Al-O bond in this surface layer is 1 or more. "Al-based and Zn-Al-based plated steel sheet having a surface layer excellent in adhesiveness."

The surface compound other than the above Al hydroxide is
In addition to Al oxides, there are phosphates, borates, silicates, heavy metal oxygenates, and the like.

The surface elements were identified and the number of moles was determined by analyzing the surface of the plated steel sheet by XPS (X-ray photoelectron spectroscopy) and using the obtained photoelectron spectrum.

[0014]

The present invention will be described in detail below.

The Al-based plated steel sheet or the Zn-Al-based plated steel sheet of the present invention is a steel sheet in which a surface layer having a predetermined thickness and composition is formed on the surface of the plating film as described above. The Al-based plated steel sheet, in addition to the steel sheet plated with pure Al, is a steel sheet plated with an Al alloy containing Si, Mn, Zn, etc. as alloy elements, and the Zn-Al-based plated steel sheet is a steel sheet.
Manufactured by dipping in a Zn-55 wt% Al bath,
It is a so-called galvalume steel plate and a so-called galfan steel plate produced by immersing in a Zn-5 wt% Al bath.

On the surfaces of these plated steel sheets, in addition to Al oxides and hydroxides, phosphates, borates, silicates, heavy metal oxyacid salts and the like are mixed, and the amount of adhesion varies. Therefore, the adhesiveness is not good, but when the surface layer is present on the surface of the plating film, the adhesiveness is good.

The surface layer needs to contain Al hydroxide in a molar ratio of 0.1 or more with respect to the surface compound other than Al hydroxide. If the molar ratio is less than 0.1, the adhesion is improved. Is not recognized.

Further, in this surface layer, Al oxide is present at the same time in addition to Al hydroxide, but when the amount of Al hydroxide present exceeds the amount of Al oxide, the adhesion is good. On the contrary, when the amount of Al oxide present exceeds the amount of Al hydroxide present, the adhesiveness deteriorates. That is, when this surface layer is analyzed by XPS, XP showing Al-O bonds
The ratio of the intensity of the oxygen spectrum of XPS showing the Al-OH bond to the intensity of the oxygen spectrum of S (hereinafter (Al-O
H) / (Al-O)) is 1 or more, the adhesion is good, and when it is less than 1, it is not good. The reason for this is not clear, but it is considered as follows.

When Al hydroxide or Al oxide is present on the surface of the Al-based plated steel sheet or the Zn-Al-based plated steel sheet, hydroxyl groups are present on the surface of the hydroxide and are also present on the surface of the Al oxide. Reacts with water in the atmosphere and hydrates, so there are hydroxyl groups. A strong bond represented by a hydrogen bond or a covalent bond is generated between this hydroxyl group and the polar group of the adhesive, but the number of hydroxyl groups generated on the surface of the Al oxide is hydrated and is the surface of the Al hydroxide. It is thought that it is extremely less than that of
When the amount of Al oxide present on the surface is larger than the amount of Al hydroxide present, the number of hydroxyl groups on the surface is small and the number of bonding points with the adhesive is small, resulting in poor adhesion.

As a result of measuring the thickness of the Al hydroxide and the surface layer containing the oxide by XPS and investigating, it was found that good adhesion cannot be obtained when the thickness is less than 1 nm. Therefore, the thickness of the surface layer needs to be 1 nm or more.

In order to form the surface layer containing the above-mentioned Al hydroxide and oxide on the surface layer portion of an Al-based or Zn-Al-based plated steel sheet, these plated steel sheets are immersed in water or steam. It may be carried out in the inside (surface treatment).

When this surface layer is formed by immersion in water, an Al-based or Zn-Al-based plated steel sheet is applied at 80 to 100 ° C.
It is preferable to apply a method (called boiling method) of immersing the surface in pure water heated to form Al hydroxide on the surface and then drying it as it is. At this time, some Al oxides are formed in addition to Al hydroxides. If the water temperature is less than 80 ° C., the reaction of forming hydroxide on the plating surface does not sufficiently occur, and a surface layer having excellent adhesiveness cannot be formed.

By varying the immersion time in water
Since the amount of Al hydroxide and oxide produced, that is, the ratio of the amount of Al hydroxide to the amount of Al oxide, can be changed, the immersion time is appropriately adjusted. Usually, the surface layer defined in the present invention can be formed by performing the immersion treatment for 20 minutes or more.

When the surface layer is formed by treatment in water vapor, pure water vapor at 80 ° C. or higher is used as Al-based or Zn-Al water.
It is preferable to use a method of spraying a system-plated steel sheet, forming a hydroxide on the surface of the steel sheet, and then drying it (steam spraying method). As in the case of the boiling method, the amount of hydroxide and oxide produced can be changed by changing the treatment time, so the treatment time is adjusted appropriately.

By subjecting the surface of the Al-based or Zn-Al-based plated steel sheet to the above-mentioned surface treatment, a surface layer containing a hydroxide and oxide of Al can be formed on the surface of the plated steel sheet. It is possible to improve the adhesiveness by modifying only the surface layer portion without changing the value. This method is extremely simple as described above and can be performed quickly.

The formation of the surface layer on the surface layer portion of the Al-based or Zn-Al-based plated steel sheet is not limited to the above method, but may be any method as long as the predetermined surface layer is formed. Good.

[0027]

[Examples] Commercially available Al-based plated steel sheets and Zn-Al-based plated steel sheets (both width 25 mm x length 100 mm x thickness 1 mm) manufactured under the normal manufacturing conditions shown in Tables 1 and 2 were used as test materials. Al hydroxide and oxide were formed on the surface by boiling method or steam blowing method. (Al-OH) /
(Al-O) and film thickness were adjusted by changing the processing time, and both were measured by XPS using O1s spectrum. The molar ratio of Al hydroxide to surface compounds other than Al hydroxide, (Al-OH) / (Al-O) and film thickness are as shown in Tables 1 and 2.

After applying a commercially available soft synthetic rubber adhesive to the surface of the test material on which the surface layer containing the oxide of Al and the hydroxide is formed, the test materials of the same size are laminated. , Baked and cured in an oven heated to 165 ° C for 25 minutes. The thickness of the adhesive was adjusted to 0.15 mm by providing a spacer.

An adhesive strength test was performed on the test materials after adhesion by the T-peel method (T-type peel test). Adhesiveness is evaluated as "adhesiveness is good" (failure is indicated by a circle) when it is broken inside the adhesive (cohesive failure), and when the entire adhesive surface is peeled off at the interface between the adhesive and the test material (interfacial peeling). Was evaluated as "adhesiveness is poor" (indicated by a mark "X"), and even if a part of the adhesive surface is peeled off at the interface, "adhesiveness is slightly good" (indicated by a mark ")".

The test results are also shown in Tables 1 and 2.
In the table, the molar ratio of Al hydroxide means the molar ratio of Al hydroxide to surface compounds other than Al hydroxide. As is clear from this result, the thickness is 1 nm or more, the molar ratio of Al hydroxide to surface compounds other than Al hydroxide is 0.1 or more, and (Al-OH) / (Al-O) is 1 or less. .
When the above-described surface layer defined in the present invention was formed, no peeling was observed at the interface between the adhesive and the test material, and the adhesiveness was good.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

The Al-based and Zn-Al-based plated steel sheets of the present invention have a surface layer having excellent adhesiveness. This surface layer can be formed by a quick and simple surface treatment,
In the future, it is expected that the adoption will increase as a joining method for materials in the industrial fields such as automobiles and home appliances.

Claims (1)

[Claims] 1. A surface layer having a molar ratio of Al hydroxide to surface compounds other than Al hydroxide of 0.1 or more and a thickness of 1 nm or more is formed on the surface layer portion, and the Al--O in this surface layer is formed.
Al against the intensity of the oxygen spectrum of XPS showing a bond
An Al-based and Zn-Al-based plated steel sheet having a surface layer excellent in adhesiveness, characterized in that the intensity ratio of the oxygen spectrum of XPS showing -OH bond is 1 or more.