JPS6028917B2 - Manufacturing method of ultra-thin tin-plated steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is capable of producing ultra-thin tin-plated steel sheets by applying electrogalvanizing to a cold-rolled steel sheet and then continuing tinning for 0.05 to 1.0 minutes per minute. The purpose is to improve weldability and solderability.

Traditionally, tin-plated steel plate, or tinplate, has been widely used as a container material.

The amount of tin plating for tinplate is 1.12 tinning and 2.8 tinning.
So, 5.69/, 8.4 evenings/power or 11.2 evenings/
The same plating amount and different plating thickness are used on both sides, but in recent years tin-free steel, which has a coating of metallic chromium and chromium hydrated oxide, has been used instead of expensive tin. (TFS) has begun to be used in large quantities as a material for beverage cans, replacing tin. Switching from expensive tinplate to cheaper TFS is being considered in the food can field.
Depending on the content, corrosion resistance may be a problem, so ultra-thin tin-plated steel sheets that take advantage of the advantages of tin, significantly reduce the amount of tin, and are cheaper than conventional tin plated steel sheets, such as JP-A No. 53-23833 and Tokuseki Akira No. 53-26236 was proposed, and it has started to attract attention from the concerned businesses. On the other hand, in the field of can manufacturing, welding cans have recently begun to be used instead of solder cans that use expensive tin, and although inexpensive welded TFS cans are being considered, they have difficulties in high-speed welding and have not been put into practical use. has various problems.

Tin-plated steel sheets exhibit excellent weldability, and ultra-thin tin-plated steel sheets that save tin and have excellent weldability, i.e., tin-plated steel sheets with a tin content of 1.0 mm/force or less, are It is starting to attract attention as a product for welded cans. However, since the tin layer of ultra-thin tin-plated steel sheets is thin, they do not have sufficient solderability or weldability, and materials with high-speed weldability are required in the can manufacturing industry. In view of the above-mentioned problems, the present invention has been developed by applying a small amount of zinc to a cold-rolled steel sheet, and then applying a coating of 1.0
The purpose is to improve the solderability and weldability of ultra-thin tin-plated steel sheets by coating them with the following tin by dipping or electroplating in an electric tinning bath.

On the other hand, when the amount of tin decreases and the amount of tin becomes less than 2.8 min/gold, the solderability deteriorates, and ultra-thin tin-plated steel sheets with a tin content of less than 1.0 y/ml are used for solder cans. is said to be difficult to put into practical use. In the container industry, since can manufacturing methods using solder are still widely used, there is a desire by those in the industry for inexpensive materials that can be applied to both welded cans and soldered cans. The present invention provides a clear answer to this demand,
The present invention provides an ultra-thin tin-plated steel sheet that has improved solderability and weldability and can be applied to solder cans, which was conventionally considered difficult when the amount of tin was small. The present invention will be explained in detail below.

The electrolytic galvanizing bath used in the present invention has acidic and alkaline properties, and acidic properties containing zinc sulfate as a main component are suitable from the viewpoint of economy and pollution prevention.

When pre-precipitated zinc is immersed into a tin plating plate, there is a substitution reaction of tin, so the zinc dissolves and after tinning, especially when tin plating is done by dipping, the amount of zinc plating before tinning is smaller than that before tinning. The amount of zinc decreases after tinning. In the case of bond immersion tin plating, tin corresponding to this amount of zinc reduction is precipitated. For this reason, the amount of electrolytic galvanizing is determined in consideration of the reduced amount of zinc so that the amount of zinc is required after tinning. As for the amount of zinc after tin plating, if the zinc content is 0.005 mm/metre or more,
Weldability and solderability are not improved.

Furthermore, if the zinc content exceeds 0.2 mm, weldability and solderability will deteriorate, and white rust will occur due to zinc corrosion, so the zinc amount is preferably 0.005 to 0.2 mm/cm. . For tinning, it is preferable to use an electric tinning bath from the viewpoint of productivity and workability.As for the electric tinning bath, an acid bath using tin sulfate, an alkaline bath using sodium stannate, and a dichloride bath are preferable. A halogen bath using tin is suitable.

As a method of tinning, electroless immersion plating is performed in the above-mentioned electric tinning bath, or electroplating is performed. In the case of bond dipping, it is possible to utilize the fact that zinc precipitated on a cold-rolled steel sheet by electrogalvanizing reacts with tin in the electrolytic tinning, and tin is precipitated by displacement. Tin can be precipitated within a short immersion time of several seconds, and the amount of precipitated tin can be adjusted by adjusting the immersion time and the strength of galvanizing. In the case of electrolytic tinning, cathodic electrolysis is used, and the amount of tin can be controlled by current efficiency and amount of electricity. Welding is difficult unless the amount of tin plating is at least 0.05 mm/metre.
Also, it is not effective in preventing white rust caused by corrosion of zinc.

Moreover, if the amount of tin exceeds 1.0 m/m, it is not possible to provide an inexpensive container material. Therefore, with an amount of tin of 0.05 to 1.0 m/m, it is possible to provide an inexpensive ultra-thin tin-plated steel sheet with excellent acid solubility and solderability, which is the object of the present invention. For solder can applications, the solderability and weldability improve as the amount of tin increases, so it is preferably 0.3 to 1.0.
Tano that range is good. If the divalent or tetravalent tin ion in the electroless tin plating bath is not more than 0.2 m/m, the substitution reaction with the zinc precipitated by pre-plating will not occur quickly, and the Since it is not economical to use more than 0.2 to 50 m/s of divalent or tetravalent tin ion.

In acid conditions of pH 7 or lower, divalent tin ions are supplied by stannous sulfate, tin borofluoride, stannous chloride, or stannous hakamate. If the pH is alkaline and exceeds 7, tetravalent tin ions are supplied using sodium stannate or potassium stannate. When using stannous sulfate, it is suitable as sulfuric acid, when using tin borofluoride and stannous chloride, the fluoride group is suitable, and when using stannous oxalate, a boron acid bath is suitable. For sodium stannate and potassium stannate, a grade containing sodium hydroxide is suitable. Furthermore, when using stannous chloride with alkaline properties, sodium hydroxide can be used. In the case of tin-plated steel sheets, melting the tin layer gives the tin a glossy surface, so for applications that require gloss, the present invention can melt the tin layer or perform flow treatment. can.

Normal electroplating is done immediately after plating,
After fitting, a reflow treatment is performed, and after rapid cooling, a passivation treatment is performed using sodium dichromate, etc., and this treatment can also be applied to the present invention.

In the case of ordinary chromic acid-based treatment, the amount of chromium deposited is less than 100% and no problem occurs. Note that treatments that do not use chromium, such as phosphoric acid, phosphates, and sodium carbonate, can also be used. There are other post-processing methods, but the post-processing methods are not particularly limited. It can also be applied without post-processing. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A 0.22 rib cold rolled steel plate was electrolytically degreased in a 7% caustic Soda solution, washed with water, electrolytically pickled in a 3% sulfuric acid solution, washed with water, and then given the following composition and treatment conditions. After electrolytic galvanizing for 0.03 pm/day, washing with water, electroless immersion in a tin plating bath having the following composition, tin plating for 0.13 pm, and 30 pm /After the car was cathodically treated in a sodium chromate solution, di-octyl sebacate (hereinafter referred to as DOS) was applied.

The amount of zinc deposited after tin plating was 0.009 mm/metre.
Composition and processing conditions for electrolytic lotus lead plating Zinc sulfate 300/Sodium sulfate 75 Tanok aluminum sulfate 25
Evening/Sono Processing Conditions Normal Temperature 4000 Processing Electricity
Typical composition and processing conditions for tin plating at 1 coulomb/d Bath composition Tin sulfate 60/day Phenolsulfonic acid 30/So Ethoxylation Q Naphtholsulfonic acid 5 Tanok Processing conditions Temperature 4500 Soaking time
1 second Example 2 The same pretreatment as in Example 1 was carried out, and electrogalvanizing was performed for 0.03 minutes using the composition and treatment conditions shown below. After washing with water, After 41 days of tin plating and cathodic treatment in 30 days of sodium dichromate solution, DOS was applied.

The amount of zinc deposited after tin plating was 0.01%. Electrogalvanizing grade composition and processing conditions Weak composition Zinc sulfate 300 t/Sodium sulfate 75 t/Aluminum sulfate
25th evening/So processing conditions: temperature
4000 Processing electricity amount 1 coulomb/d force Tin plating grade composition and processing conditions Rich composition Tin sulfate 60 evenings/day Phenolsulfonate 30 evenings/so Ethoxylation Q Naphtholsulfonic acid 59/day Treatment conditions (electroless immersion After bond processing, electrolytic treatment) Ordinary temperature 4500 soaking hours
0.9sa processing electricity amount
Example 3 The same pretreatment as in Example 1 was carried out at 3 coulombs/d, and electrogalvanizing was performed at 0.14 coulombs/day using the composition and treatment conditions shown below. After washing with water, the following composition and treatment conditions were applied: Tin plating was carried out at 0.64 pm under processing conditions, reflowed and the tin melted, cathodically treated in a 30 ton solution of sodium dichromate, and then coated with DOS.

The amount of zinc deposited after tin plating was 0.14 mm/metre. Weak composition and treatment conditions for electrogalvanizing Bath composition and treatment conditions for electrogalvanizing Weak composition: tin zinc sulfate 250 t/ammonium sulfate 80 t/sodium sulfate
50 evenings/sodana acid 3
09/〆Processing conditions Normal temperature 40゜Processing electricity amount
4 coulombs/d force Tin plating common bath composition and processing conditions Composition tin sulfate 4M/phenol sulfonic acid 30 tanoxethoxylated Q
Naphtholsulfonic acid 5 nights/so Processing conditions Normal temperature 45o0 Processing electricity amount 12 coulombs/d〆Example 4 The same pretreatment as in Example 1 was carried out, and the following composition and treatment conditions were used for 0.17 nights/〆 After electrolytic galvanizing and washing with water, tin plating was carried out for 0.11 evenings using the following composition and processing conditions, and after cathodic treatment in the sodium dichromate solution for 30 evenings, DOS was applied. It was oiled.

The amount of zinc deposited after tin plating was 0.17 mm/metre. Electrogalvanizing composition and processing conditions Bath composition Zinc sulfate 380 t/Sodium sulfate 72 t/Magnesium sulfate
61 evening/so Processing conditions Normal temperature 60qo Processing amount of electricity
Example 5 The same pretreatment as in Example 1 was carried out at 5 coulombs/d, followed by electroplating with the following composition and treatment conditions at 0.01 t/d, followed by washing with water. Tin plating was carried out at 0.45 mm under treatment conditions, and after 30 evenings of cathodic treatment with the sodium dichromate solution, DOS was applied.

The amount of zinc deposited after tin plating was 0.01 mm/metre. Common composition and processing conditions for electrogalvanizing: Zinc chloride 200 t/s Ammonium chloride 250 t/s Sodium chloride
80 evenings/so Sodium fluoride 5 evenings/so Treatment conditions Bath temperature: 35 q0 Processing electricity amount 0.3 coulombs/d Tin plating composition and treatment conditions Stannous chloride 75 evenings/Sodium chloride 45 evenings/Ku Sodium
25th evening/potassium hydrogen fluoride
5M/so Processing conditions normal temperature 65oo bonding time
0.9 Sand processing electricity amount
Example 6 The same pretreatment as in Example 1 was carried out at 3 coulombs/d, and 0.02/pillow electrogalvanization was performed with the following composition and treatment conditions, and after washing with water, the following composition and treatment conditions were applied. After 0.43 evenings of tin plating, and 30 evenings of cathodic treatment with the sodium dichromate solution, DOS was applied.

The amount of zinc deposited after tin plating was 0.02 mm/metre. Composition and processing conditions for electrolytic galvanizing General composition Zinc sulfate 350 t/ammonium sulfate 30 t/s Processing conditions Rating temperature 4500 Processing electricity 0.6 coulombs/d force Wearing composition and processing conditions for tin plating Rating composition Sodium stannate 100/Sodium hydroxide 159/So Processing conditions Normal temperature
85oo processing electricity amount
Comparative example of 15 coulombs/d 1 Perform the same pretreatment as in Example 1, apply tinning at 0.7 coulombs/force under the composition and treatment conditions shown below, perform reflow, and melt the tin. , 30 evening/cathode treatment in the sodium dichromate solution and oiling with DOS.

Tin plating case composition and treatment conditions Bath composition Tin sulfate 60 t/t Phenolsulfonic acid 30 t/t Oxylated Q naphtholsulfonic acid 5 t/t Treatment conditions Bath temperature 4500 Processing electricity amount 20 coulombs/d〆 Comparative example 2 The same pretreatment as in Example 1 was carried out, the tin plating was carried out in the same manner as in Comparative Example 1 for 0.7 evenings, and the car was cathodically treated in a sodium chromate solution for 30 evenings, and the car was coated with DOS. .

The tin-plated steel plates obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were subjected to the following solderability, salt water fog test, rust resistance test by indoor exposure, and weldability test.

{1} Solderability test A rectangular specimen of 75 ribs x 25 skins was cut out, and the short sides were bent so that the cross section was parallel.

After soaking this in flux to a depth of 5 skin, 29
The sample was vertically immersed in pure tin solder solution at 0° C. for 1 minute, and the sample was taken out and rapidly cooled in water. The crease of the specimen was opened, and the height of the solder rising from the solder surface due to capillary action was evaluated as solderability. The higher the height of the raised solder, the better the solderability. ■ Rust test by indoor exposure After being exposed indoors for 4 weeks, the state of rust was examined and evaluated based on the area ratio of rust occurrence.

The lower the number, the better the corrosion resistance. Glue After heating the weldability test sample at 210°C for 15 minutes, welding was performed using a test welding machine at a frequency of 60Hz, a lap width of 0.4, and a speed of 7.
．． Welding No. 1 under the conditions of 2 min/min and a pressure of 45 k9/min.
Table note 11) Indoor exposure test: Shows the rust occurrence area rate.

■ Weldability: Indicates the weldable current range. I did it.

The maximum current that would not cause splash (molten iron sputtering due to overheating) during welding by electric resistance heating and the minimum current that would provide welding strength that would not cause leakage were measured. This difference was defined as the weldable current range. The larger this range is, the better the weldability is. This weldable current range was measured.

As shown in Table 1, the ultra-thin tin-plated steel plate produced by the method of the present invention was found to have excellent solderability and weldability.

Claims (1)

[Claims] 1. In a method for producing an ultra-thin tin-plated steel sheet, the amount of zinc after tin-plating is 0.005 to 0.05 on one or both sides of the cold-rolled steel sheet.
After electrogalvanizing at 0.2g/m^2, the amount of tin is 0.
．． A method for producing an ultra-thin tin-plated steel sheet, characterized by applying electro-tinning of 0.05 to 1.0 g/m^2. 2. In the method for producing ultra-thin tin-plated steel sheets, the amount of zinc after tin-plating is 0.005 to 0.05 on one or both sides of the cold-rolled steel sheet.
Ultra-thin tin characterized by electroless galvanizing to a tin content of 0.2 g/m^2 and then electroless immersion tinning with a tin content of 0.05 to 1.0 g/m^2. Manufacturing method for galvanized steel sheets. 3 Electroless immersion tin plating bath absorbs 0.2 divalent tin ions.
The method for producing an ultra-thin tin-plated steel sheet according to claim 2, which is an acidic tin plating bath containing ~50 g/l or an alkaline tin plating bath containing 0.2 to 50 g/l of tetravalent tin ions. 4. In the method for producing an ultra-thin tinned steel sheet, the amount of zinc after tinning is 0.005 to 0.005 on one or both sides of the cold rolled steel sheet.
After electrolytic galvanizing to a concentration of 0.2 g/m^2, electroless immersion tinning was followed by electrolytic tinning to a tin amount of 0.05 to 1.0 g/m^2. A method for producing ultra-thin tin-plated steel sheets. 5 The electroless immersion tin plating bath absorbs 0.2 divalent tin ions.
Production of an ultra-thin tin-plated steel sheet according to claim 4, which is an acidic tin plating bath containing ~50 g/l or an alkali tin plating bath containing 0.2-50 g/l of tetravalent tin ions. Method.