JPS58193389A - Manufacture of zinc-electroplated steel sheet having resistance to fingerprint - Google Patents

Abstract

PURPOSE:To economically manufacture a zinc-electroplated steel sheet excellent in resistance to fingerprint and corrosion, by temper-rolling said steel sheet after the completion of a zinc-electroplating process in a manner such that the surface of the steel sheet is intensively flattened. CONSTITUTION:Zinc is electrodeposited on a steel sheet in a plating bath such as an industrially useful sulfuric or chloride one. After the completion of said electroplating process, the steel sheet is temper-rolled in a manner such that the surface roughness of the steel sheet comes to an extent of 1-7mum by the indication of the max. height Rmax defined by JIB061. The reduction ratio of said temper-rolling is usually below 1.5% enough. As a result, the ridged parts on the surface of the steel sheet which have come in direct contact with fingers so far are flattened, the wettability of the surface is lowered to reduce the adhesion of sweat, etc., and the adhesion of sweat, etc. to the trough parts is not formed. Consequently, the adhesion of fingerprint as a whole is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an electrogalvanized steel sheet having anti-fingerprint properties, and particularly to an economical method for manufacturing an electrolytic galvanized steel sheet that is resistant to fingerprints.

Electrogalvanized steel sheets are used in automobiles, home appliances, building materials, etc., and the demand for them is increasing year by year.However, the performance required of galvanized steel sheets is also becoming more diverse, and the appearance of home appliances is particularly important. There is.

In general, electrogalvanized steel sheets are susceptible to fingerprints, and if workers' fingerprints are left on the sheet during assembly, these fingerprints will stand out after painting, significantly impairing its appearance and lowering its commercial value.

The conventional manufacturing method for electrogalvanized steel sheets with anti-fingerprint properties is to add anti-fingerprint properties by adding organic or black oxide to electrogalvanized grade**, drying the baking process, and coating with lI41i. . However, this method has the following problems.

(b) The manufacturing technology for stably applying 4 grades has not been established.

(b) The hardness and abrasion resistance of the thin film required for passing the line through the line are insufficient.

e) Cor1) The blocking resistance of Nishiku Kotei is poor.

2) Coating and baking after electrogalvanizing increases manufacturing costs by adding a drying process.

The object of the present invention is to solve the problems of the prior art described above and to provide an economical method for manufacturing an electrogalvanized steel sheet having anti-fingerprint properties.

The gist of the present invention is as follows.

In other words, after the electrogalvanizing process, the surface roughness f of the steel sheet
This is a method for producing an electrogalvanized steel sheet having anti-fingerprint properties, which is characterized by temper rolling such that iL decoration ax is within the range of 1 to 7 μm.

The mechanism by which fingerprints adhere is thought to be that sweat and dirt (hereinafter referred to as sweat) are transferred from the surface of the finger and adhere to the surface of the plated steel plate.

The Wfr surface profile of conventional electrogalvanized steel sheet is gi
Shown in the figure. In Figure 1, the vertical axis is 5000 times, and the horizontal axis is Fi10.
Although it has been magnified 00 times, it is impossible to completely wipe off sweat and other substances that have adhered to the rounded surface, which has a very uneven surface.

Even after the sweat has dried, it remains on the steel plate as fingerprints.

@1 When examined in detail, the valley aX is relatively deep.

2. Your fingers can't touch it, so sweat won't stick to it. On the other hand, direct contact with large peaks 3.4ri fingers increases sweat and the like. The galvanized surface of the +fi side of the large ridge 3.4 has small irregularities, so it is easy for liquids to adhere to it.

Based on these studies, the inventors of the present invention discovered that smoothing the surface of a plated steel sheet by applying compression can provide a surface that is less likely to attract fingerprints.

FIG. 2 shows the WLR surface profile of a nine-dimensional galvanized steel sheet subjected to surface 1IIlii roughening by temper rolling according to the present invention. The magnification is the same as in FIG. The surface roughness after temper rolling is smoother than that before II quality rolling. In particular, the peaks 3.4 in Fig. 1 are smoothed, and the valleys s1 and 2 remain as they are. Therefore, the peaks that conventionally come in contact with fingers become smoother, reducing the wettability of the surface and reducing the adhesion of sweat, etc.; It has become attached.

In the present invention, the surface roughness after homogeneous pressure is JISB06
Although the display of the rut large tube max specified in 01 is limited to the range of 1 to 7^ shoulder, when the Rmax of the salt mountain exceeds 7μ, the effect of preventing fingerprint adhesion by surface conditioning is small, and on the other hand, surface #I /4 If Rmax is less than 1 μm by excessively applying Rmax, the surface of the galvanized steel sheet will become mirror-like and traces of fingerprints will become more noticeable, so Rmax should be set to 1 to 7.
The area was limited to shore m.

1 The electrolytic galvanized steel sheet temper-rolled according to the present invention has no special specifications, but a sulfuric acid bath used industrially,
Any round steel plate that has been electrodeposited with zinc in a plating bath such as a chloride bath may be used.

The surface roughness of the steel material is 114'i [JE] in the present invention, and the rolling reduction rate is not limited, but it is usually 1.511i.
The following can be effective.

In the chromate treatment of a high-quality electric galvanizer, conventional electrolytic galvanized steel sheets have sharp edges at peaks 3 and 4 of the cross-sectional profile shown in Figure 1.
There was a drawback that the galvanized surface could not be completely coated, which caused defects in the coating.

On the other hand, the electrogalvanized steel sheet that has been surface-conditioned by temper rolling according to the present invention has a smooth surface, the chromate treatment film adheres uniformly, there are fewer defects in the film, and the corrosion resistance is improved even if the same chromate treatment is applied. There are four advantages to doing so.

Note that in the method of the present invention, coating and baking of paint is different from the conventional method of preventing fingerprint adhesion by drying.
Since it is N-toned, there are no problems with coating hardness, abrasion resistance, or scratching, and only fingerprint resistance can be improved.

Example After plating electrocurved plated steel plates under the conditions shown in Table 1, that is, test materials 11 to 5 - actual pressure iAt, 2 to 6
In the table m@fgJ1t', A5r and Hmax do not satisfy the limited range of the present invention. Sample materials 16 to 8 had surface roughness [1 m! This is a comparison material that did not undergo Step 1. The chromate treatment was carried out under the same conditions as the usual chromate treatment solution at a liquid temperature of 40° C. and an immersion time of 4 seconds, and the fingerprint resistance, corrosion resistance, etc. were evaluated and the results are also shown in Table 1.

The fingerprint resistance test was conducted in two ways: by actually applying fingerprints with the thumb and by applying artificial sweat made by combining sweat components, and after 24 hours, the residual status was visually judged. . The criteria for evaluation was rated 5 for no marks at all, 1 for clear marks, and 1 to 5 in between.

Corrosion resistance was evaluated by the salt spray test based on the time spent in the trench at the initial stage (1).

As is clear from Table 1, samples 1 to 4, which are examples of the present invention, have excellent fingerprint resistance and corrosion resistance.
Since the surface roughness Rmax is α9 μm, the fingerprint resistance is slightly inferior to that of the examples of the present invention, and the comparative examples Muro to 8, in which the roughness fA* is not carried out, are overall inferior in fingerprint resistance and hardness.

The present invention makes it possible to economically produce an electrogalvanized steel sheet with excellent fingerprint resistance and corrosion resistance by temper rolling the electrogalvanized steel sheet to have a surface roughness kbnax in the range of 1 to 7μ.

[Brief explanation of the drawing]

Figure 1 is an enlarged cross-sectional view showing the cross-sectional profile of an electrogalvanized steel sheet by the conventional method, and FIG. 2 is an enlarged cross-sectional view showing the cross-sectional profile of the electrogalvanized steel sheet by the method of the present invention. Representative Nakaji Muko

Claims (1)

[Claims] (1) Surface roughness Rm of steel plate after electrogalvanizing process
A method for producing an electrogalvanized steel sheet having anti-fingerprint properties, which comprises heat rolling so that ax is within the range of 1 to 7 mm.