JPS59145794A - Plated steel sheet for can making - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plated steel sheet for can manufacturing having different plating layers on the front and back surfaces.

Conventionally, tin plated with tin and TFS-CT with ultra-thin chrome plating have been widely used as plated steel sheets for can manufacturing, but as is well known, tin is extremely expensive and there are resource constraints, so thinner sheets are used. While the trend toward
-The current situation is that the transition to CT, etc. is progressing. However, TF'S-CT has disadvantages such as poor high-speed weldability, which severely limits the ability to make cans by wire seam welding. In this respect, tinplate has excellent weldability and solderability, but due to the reasons mentioned above, it has become thinner.
As the thickness becomes thinner, the solderability becomes inferior, and this will accelerate the decline of solder joint can manufacturing, which is disadvantageous in terms of cost. In addition, as tin becomes thinner, its corrosion resistance deteriorates, so this supplementary measure has become extremely important.

Furthermore, tinplate has disadvantages such as poorer coating adhesion than TFS-CT.

Therefore, considering the current state of these steel plates for can manufacturing, there is a strong desire to develop high-performance, low-cost steel plates that meet new needs.

Therefore, the present inventors conducted a study on steel sheets for can making from a wide range of angles based on these current circumstances, and as a result, they came to develop a plated steel sheet for can making that has features not seen in the past.

That is, one surface of the steel plate (the surface that becomes the outer surface of the can diameter) has an Fe-Sn alloy layer of 0.1 to 0.7II in terms of amount.
The other surface (the surface that becomes the inner surface of the can diameter) has a free Sn content of 0.1 to 12 g/rrl Sr.
l plating layer and further metal Cr layer at 2 to 40 m9/r
rt, and has a chromium hydrated oxide layer on the top layer on both sides of 2 to 151% in terms of Cr.Characteristics of the plated steel sheet The area where Fe-
By forming a Sn alloy layer, the paintability is significantly improved, and in particular, it is given the function of suppressing corrosion under the coating film, and the amount of tin is reduced. Fu on the surface that touches! J-8n and metal C
By forming r, corrosion resistance is significantly improved, and
By forming a chromium water-conserving oxide layer on the uppermost layer on both sides, it is possible to impart complete performance. As described above, it is essential that the coating thickness on each side of the plated steel sheet, which has different coating layers on both sides, is within the following range. In other words, the Fe-Sn alloy layer on the surface facing the can manufacturing surface must have an Sn content of 0.111/n1 or more, and if the thickness is less than this, properties such as corrosion resistance, paintability, and weldability will deteriorate. I can't grant it anymore. Also, the upper limit is 0.7 in Sn amount conversion! The reason for setting it to i'/m'' is that if it exceeds this value, the coating properties will be poor among the above-mentioned characteristics, and it will take time to form the upper metal layer, making it difficult to form a uniform alloy layer.

On the other hand, the lower limit of the Sn amount ()IJ - Sn amount) on the surface that becomes the inner surface after can manufacturing is set to 0.11//rrl because below this, weldability deteriorates and corrosion resistance cannot be expected.

In this case, even if the Fe-Sn alloy layer is threaded in addition to F') -Sn, the amount of F'J -Sn is o, t.
This indicates that g7m or more is required. And S
The reason why the upper limit of the n thickness is set to 121/rrt is that Sn is expensive if it exceeds this value, so it is not cost-effective as a material for cans in order to improve corrosion resistance.

Furthermore, the Cr layer formed on this Sn layer has a thickness of 2 to 40 rr.
It is necessary that u; y/m be in the range, and if it is less than 21 V/m, the corrosion resistance, especially under-coating corrosion resistance, will be poor, and if it exceeds 40 m9/m, the corrosion resistance will be excellent, but on the other hand,
Weldability becomes poor.

The thickness of the chromium water conserving oxide layer, which is the top layer of the coating layer on both sides, is 2 to 15 m9/nl in terms of Cr.
This is because if it is less than m9/I, no deterioration in coating corrosion resistance is observed, and if it exceeds 15 In9/rrl, weldability is reduced.

As mentioned above, a plated steel sheet for can manufacturing having a composition coating that differs on each side of the steel sheet has various characteristics, and these coatings can be easily formed by the method described below. That is, to give an example, Sn plating can be easily obtained by using a ferrostane bath, and a Fe-Sn alloy layer can be easily obtained by reflow treatment (heating diffusion treatment) after Sn plating. Furthermore, the metallic Cr layer can be formed using an anion-added chromic acid bath (e.g. Sargent bath), and the top layer of chromium hydrated oxide layer can be formed using a chromic acid bath (e.g. Sargent bath). chromate treatment baths (e.g. chromate baths). A different film can be easily formed on each side using these treatment baths.Next, the present invention will be described in more detail with reference to Examples.

Example 1 One side (corresponding to the outer surface of can manufacturing) of a thin steel plate for cans (plate thickness 0.24mm, T-4CA material) was subjected to Sn plating (plating using a ferrostane bath) on various metals, and subjected to reflow treatment. After alloying, the other surface (corresponding to the inside surface of the can) is coated with S to a thickness such that 0.2 g/Sn remains even after the flow treatment.
N-plated. Furthermore, chromium hydrated oxide material is applied to the outer surface in various thicknesses (-1 metal carbon is applied to the inner surface).
A sample material was prepared by applying an r layer to a thickness of 54 mm and a chromium hydrated oxide layer to a thickness of 87 nm/nl. The weldability of the test materials was examined using a wire seam welding machine, and the behavior of corrosion under the coating was examined using a filliform corrosion test.

The FIRIFOAM corrosion test method is as follows.

0 filiform corrosion test: Apply epoxy phenol paint to a thickness of 50 m9/dm2, bake it, make cross cuts with a cutter, and conduct salt spray test (JI
S-Z-7321) for 4 hours, and then kept at constant temperature and humidity (38°C).

After being kept for 3 weeks in a room with a relative humidity of 80%, the state of corrosion under the coating was evaluated.

The evaluation test results are shown in Table-1.

As is clear from this result, F
The e-Sn alloy layer has a thickness of 01 to 07 g/ze in terms of Sn content, and the chromium hydrated oxide layer has a thickness of 2 to 1 in terms of Cr.
It is clear that a plated steel sheet having a thickness of 54 mm can be an excellent material for cans.

Example 2 Sn plating of various thicknesses was applied to one side (corresponding to the outside surface of the can) of the same thin plate as in Example 1 in a ferrostane tin plating bath, and Cr of various types was applied in a dilute Sargent bath.
layers were formed and a chromium hydrated oxide layer was formed on top. On the other hand, on the other surface (corresponding to the outer surface of the can), a Fe-Sn alloy layer with an Sn content of 0.31/rrt is formed, and a chromium hydrated oxide layer with an amount of 10/rrt in terms of Cr is further formed. This material was used as the test material. The weldability of the test materials was examined using a wire seam welder, and the behavior of corrosion under the coating was examined using an LCC test. The LCC test method is as follows.

OLCC test: 50 mti of epoxy phenol paint
After painting to a thickness of /m'', make a cross cut, 1.5%
Nact, 1, immersed in a 5% citric acid solution at 50°C for 3 days, and after peeling off the coating, the coating surface was evaluated.

The planned test results are shown in Table 2. As is clear from these results, in terms of overall performance, free Sn is present on the barrel side of the inner surface after can manufacturing.
It has an Sn layer with an amount of 0.1 to 1217, and
A plated steel sheet having a Cr layer with a thickness of 2 to 40 rn9/yr+'' and a chromium hydration oxide layer of 2 to 40 mg/- in terms of Cr on the top layer can be an excellent material for cans. it is obvious.

[Table 2] Relationship to the case of Kazuo Wakasugi, Commissioner of the Japan Patent Office Applicant 4th generation Qj person j'e I'Ji 3307 Marunouchi Shigesu Building, 2-6-2 Marunouchi, Nanaida-ku, Tokyo, subject of amendment Amendment The following matters will be amended in the specification of Patent Application No. 1.

Record 1. The scope of claims is amended as shown in the attached sheet.

2. r LC on page 9, 5th line, 4th line and 3rd line from the bottom
Correct the words ``C exam'' to ``r UCC exam'' respectively.

3, in page 11 [Table-2] r　LCC exam'' r　UCC exam''.

Punch Claimed range F'e-Sn alloy layer on one side of the steel plate 0.1 to o in terms of Sn
, 74 and chromium hydrated oxide monolayer, 2 to 15 in terms of Or
mV/m2, with a free Sn layer 0.1-12 on the other side
Sn plating layer with t/-2, metal Cr layer 2 to 40
mF/- and chromium hydrated oxide layer 2 to 1 in terms of Cr
5 mt/m2. A plated steel sheet for can making.

Claims (1)

[Claims] An Fe-8s alloy layer on one side of the steel plate is 0.1 to 0.0 in terms of Sn.
7II/m and chromium hydrated oxide layer 2 to 15■ in terms of Cr
/m and a free Sn layer o, i~12g on the other side
/m Sn plating layer, metal Cr layer 2 to 40 m9
/rrl and chromium hydrated oxide layer 2~2 in terms of Cr
15 m9/m". A plated steel sheet for can making.