JPS6035440B2 - Manufacturing method of bright tin-plated steel plate with excellent paint adhesion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bright tin-plated steel plate with excellent paint adhesion.

In recent years, can manufacturing methods have made tremendous progress, and in addition to the conventional can manufacturing method using soldering, tin-free steel (hereinafter referred to as TFS) has been developed.

), the can body bonding method using a nylon-based organic adhesive has become widespread and has been applied to many carbonated beverage cans and fruit juice cans, and TFS is often used as a material for cans. In this can body bonding method using a nylon-based organic adhesive, the organic adhesive is interposed between the coating on the surface of the adherend and the applied paint, and the adhesion between the adherend and the paint is The adhesive strength between the organic adhesive and the paint allows the can body to be joined. However, although tin-plated steel sheet is superior to TFS in terms of appearance and protection of contents,
Paint adhesion is poor, making it difficult to join can bodies using organic adhesives. Furthermore, when this can body joining method is applied, a fruit juice beverage can that is filled with contents that have been heat sterilized at a temperature of 80 to 10,000 °C, ie, a so-called hot pack, is used.
It has been considered impossible to apply tin-plated steel sheets to cans that require so-called retort sterilization, which is sterilization under pressure at temperatures above 0:00. US Pat. No. 3,245,577 is a proposal to improve the adhesion of a tinned steel sheet to a coating film. This method involves plating chrome on the tin layer, then coating the top layer with paint and curing it, but although the adhesion of the paint film at room temperature is improved, it is not sufficient and hot packs are required. It was impossible to apply this method to cans that undergo retort sterilization or to cans that undergo retort sterilization. The present invention provides a tin-plated steel sheet that exhibits excellent coating film adhesion, high-temperature water resistance, and retort resistance at room temperature under the above-mentioned heat sterilization conditions.

Furthermore, the present invention provides a tin-plated steel sheet that maintains the gloss of tinplate and satisfies the above-mentioned characteristics. That is, in the present invention, after forming a tin layer on both sides of a steel plate and a nickel layer at 1 to 100 o// on the top layer, heating to a temperature higher than the melting point of tin,
Melt tin and rapidly cool it. Subsequently, electrolytic chromic acid treatment is performed to form a metal chromium layer of 10 to 100 and a chromium hydrated oxide layer of 5 to 30 in terms of chromium on the top layer, which was previously impossible. A bright tin-plated steel plate is obtained which has been subjected to a can body joining method using an organic adhesive. In the can-bonding method using an organic adhesive to join the can body by joining the front and back sides of tin-plated steel plates, both sides of the tin layer are plated with nickel, the tin is melted, and then electrolytic chromic acid treatment is applied. This achieves the purpose of the present application.

On the other hand, in order to improve the adhesion of coating only on the inner or outer surface of the can, it is possible to nickel plate only one side of the tin layer, melt the tin, and then perform a chromic acid treatment. The tin layer of the tin-plated steel sheet of the present invention is suitably 1.12 to 11.2 m/m in order to obtain the gloss characteristic of tin.

Excellent coating film adhesion is shown when the amount of nickel exceeds 100 o/〆, and even higher coating adhesion cannot be obtained even when the amount exceeds 100 o/〆. A ratio of 9/1 to 100 is suitable because it is not possible to obtain the gloss characteristic of tinplate in the heating process for melting tin.

After forming the nickel layer, the purpose of heating above the melting point of tin is to increase the luster of the tin layer, but by melting the tin, an alloy of tin and nickel is formed, and the combination of tin and nickel is heated. This is to strengthen the bond at the interface. moreover,
The upper metallic chromium layer and chromium hydrated oxide layer are effective in coating adhesion at room temperature, high temperature water resistance, and retort resistance, and due to the synergistic effect with the nickel layer on the tin layer, A tin-plated steel sheet suitable for can manufacturing using a can body joining method using an organic adhesive, which cannot be obtained with a plated steel sheet, can be obtained.

In the method of U.S. Pat. No. 3,245,577, in which chromium plating is performed on the tin layer and the chromium is coated, after tin plating, which is used for ordinary tin-plated steel sheets, the tin layer is coated with chromium. Although the coating adhesion was improved compared to the cathodic treatment method, the high-temperature water resistance and retort resistance were inferior, and it was difficult to apply the can body joining method using an organic adhesive. The peeling of the paint film occurs not at the interface between the chromium hydrated oxide layer and the paint film, but between the tin layer and the metal. occurs at the interface with the chromium layer or chromium hydrated oxide layer. In other words, this suggests that the bond between the tin layer and the metallic chromium layer or the chromium hydrated oxide layer is weak.
By interposing nickel and melting tin, peeling on the surface of the tin layer is eliminated and the adhesion between nickel and tin and between nickel and the metal chromium layer is strengthened. The amount of metallic chromium is 10
If it is less than 9/100%, the coating adhesion, hot water degradation resistance and retort resistance will not improve, and as the amount of metallic chromium increases, the above properties will improve, but even if it exceeds 9/100,
A ratio of 10 to 100 female/width is suitable because not only the effect is not further restricted, but also the gloss of the tin layer peculiar to tin-plated steel sheet is lost. The amount of chromium hydrated oxide is required to be 5 or more in terms of high temperature water resistance and retort resistance. If it exceeds 30 tano, the tin paper will lose its luster and spoil its appearance, so
9/〆 of 30 is preferable.

Hereinafter, the contents of the present invention will be explained in detail.

First, a cold-rolled steel sheet is degreased and pickled, then subjected to electric tin plating, followed by nickel plating and heated above the melting temperature of tin to melt the tin.

During the melting process of tin, an alloy of tin and nickel is formed at the interface between the tin and nickel. After melting the tin, it is rapidly cooled, washed with water, and then electrolytically treated with chromic acid to form a metallic chromium layer on the nickel layer or tin-nickel alloy layer. A hydrated oxide layer is formed, washed with water, dried, and then coated with oil to obtain the bright tin-plated steel sheet of the present invention. For electric tinning, a known tinning grade can be used, and a tin sulfate bath, an acidic type such as tin chloride, or an alkaline type such as sodium stannate or potassium stannate can be used.

For electrolytic nickel plating, any of nickel sulfate, nickel chloride, sulfamine acid, and ammonium nickel sulfate can be used. The amount of the nickel layer in the tin-plated steel sheet of the present invention is as small as 1 to 100 times a day, and if the nickel concentration is about 1/10, which is lower than the normally used nickel concentration, the nickel precipitation efficiency will be low.
In particular, when the amount of nickel is less than 9/5, it becomes easy to control the amount of nickel layer. Furthermore, similar effects can be obtained by alloy plating of tin and nickel. For example, the desired tin-plated steel sheet can be obtained by alloy plating of tin and nickel containing tin chloride and nickel chloride. Next, for the electrolytic chromic acid treatment, we use a general method consisting of chromic acid anhydride used in TFS production as the main component and one or two auxiliary agents such as sulfuric acid, fluorine compounds, aromatic disulfonic acid, and thiourea added. can.

Cathode treatment is performed in these chambers to form a metallic chromium layer and a chromium hydrated oxide layer. 3 in sodium dichromate solution, which is commonly used as a post-treatment for electro-tinning.
~4C/d Since it is difficult to precipitate metallic chromium using that cathodic treatment method, it is suitable to use a case containing chromic anhydride as the main component. Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A rolled steel sheet with a thickness of 0.21 mm was electrolytically degreased in a 7% sodium hydroxide solution, washed with water, electrolytically degreased in a 3% sulfuric acid solution, washed with water, and then placed in a sulfuric acid tin plating bath. After rinsing with water, nickel plating is performed using the following nickel sulfate plating composition and processing conditions to form a nickel layer of 5 and 9 on the tin layer. After the tin was melted and rapidly cooled in a reflow process, electrolytic chromic acid treatment was performed using the following electrolytic treatment composition and treatment conditions to obtain a metal chromium layer of 80 p/15/9/〆 in terms of chromium. A chromium hydrated oxide layer was obtained.

After washing with water and drying, di-octyl sebacate (hereinafter referred to as DOS) was applied. '1- Electrolytic nickel plating grading composition and heat treatment conditions nickel sulfate grading composition
200 yen/boric acid
10 evenings/so Processing conditions Current density 0.2 distance/d〆 Processing time
1. Current sand temperature
45CO (2' Electrolytic chromic acid General composition and treatment conditions Conditional composition Chromic acid anhydride 30 evenings / Sodium fluoride 2 evenings / So Treatment conditions Current density 4 pine / d〆 Treatment time
1. Lump sand temperature
55CO Example 2 Example 1
The same pretreatment as above was carried out, and 1.7% of
After applying final tin plating and washing with water, electrolytic nickel plating was performed using the following nickel sulfate plating composition and processing conditions to obtain a nickel layer of 20 o / final on the tin layer, followed by a reflow process. After melting and rapidly cooling tin, electrolytic chromic acid treatment is performed using the following electrolytic treatment composition and treatment conditions.
After obtaining a metallic chromium layer of 20 mm/force and a chromium hydrated oxide layer of 20 mm/force in terms of chromium, DOS was applied.

, m Electrolytic nickel plating composition and processing conditions Rating composition Nickel ammonium sulfate 100/sodium citrate
15 evening/so Processing conditions Current density IA/d〆 Processing time
ISeC bath temperature
460 ■ Electrolytic chromic acid bath composition and heat treatment time Composition Chromic anhydride 60 t/sulfuric acid
0.69 evening/evening processing condition current density
Processing time at 2 ships/d
1 second case temperature
55q○ Example 3 The same pretreatment as in Example 1 was carried out, and a tin-plated steel plate was applied for 5.6 days/day in a sulfuric acid tin plating bath, and after washing with water, the following nickel sulfate tin plating bath composition and Electric nickel plating is performed under the processing conditions, and 6
After obtaining a nickel layer with a thickness of 3/50 and then melting tin in a reflow process and rapidly cooling it, electrolytic chromic acid treatment was performed using the following electrolytic treatment composition and treatment conditions to form a metallic chromium layer with a thickness of 3/50. After obtaining a chromium hydrated oxide layer of 8 p/ by chromium calculation, I applied DOS.

'1) Electrolytic nickel plating composition and processing conditions Nickel sulfamate 100%/boric acid
15 evening/so Processing conditions Current density Tsumugi/d Processing time
1 second case temperature
5000 {12) Electrolyte.

Chromic acid bath composition and treatment conditions Rich composition Chromic anhydride
30 evening/potassium fluoride
1.5 m/s Processing conditions Current density
40A/d〆processing time 1
Second grade temperature 5yo Example 4 Perform the same pretreatment as in Example 1, tin the pillow for 2.8 nights in a sulfuric acid tin plating bath, and after washing with water, the following nickel sulfate plating bath composition: Electrolytic nickel plating was performed under the following processing conditions to obtain a nickel layer of 90 mg/pillow on the tin layer, followed by melting and quenching the tin in a reflow process.
After performing electrolytic chromic acid treatment with the following electrolytic treatment composition and treatment conditions to obtain a metallic chromium layer of 30 o/〆 and a chromium hydrated oxide layer of 15/9 in terms of chromium, DO
S was anointed with oil.

tl) Electrolytic nickel plating composition and processing conditions General composition Nickel sulfamate 150/soboric acid
10 evening/evening treatment conditions current density 4. /d processing time
1 second bath temperature
5000 ■ Electrolytic chromium acid rating composition and processing conditions Rich composition Chromic anhydride 35 t/Ammonium fluoride 1.5 t/t Treatment conditions Current density
3pu/d closing processing time
1 second bath temperature
Comparative Example 1 The same pretreatment as in Example 1 was carried out, followed by 2.89% tin plating in a known sulfuric acid tin plating bath, and after melting the tin in the reflow process, the following DOS
anointed with oil.

Bath composition Sodium dichromate 30 min/s Treatment conditions Current density 3 A/d Treatment time
1 second Comparative Example 2 The same pretreatment as in Example 1 was carried out, the tin plating was carried out for 2.8 days in a known sulfuric acid tin plating bath, and the tin was melted in the reflow process. Patent No. 3,245 57
By the method described in No. 7, a metallic chromium layer of 9/20 and a chromium hydrated oxide of 4/9/1 in terms of chromium were obtained.

After washing with water and drying, I applied DOS. Common composition Chromic anhydride 270/sulfuric acid
2.7 evening/evening processing conditions current density
20A/d treatment time
1 second bath temperature
The following various coating film adhesion tests were conducted on the tinned steel plates obtained in Examples 1 to 4 and Comparative Examples 1 and 2, and the results are shown in Table 1.

(1) Paint adhesion test A phenol-epoxy paint was applied to the surface of one sample at a rate of 60 m/d, and baked at 210°C for 18 minutes.

The same paint was applied to the other side with a 9/d finish of 25, and moths were attached under the same conditions. This single sample was cut into a serpentine cut with a length of 10 on each of the 5 sides. Two specimens with different coating thicknesses were placed on top of each other, and a 100 m thick nylon film was sandwiched between them.
Using a hot press, 12 sands were heated at 20,000 yen, and then crimped at 200 qo for 30 seconds under a pressure of 4k9/ground. This adhesive specimen was tested at 180% by tensile testing machine.
0 peel was performed and the peel strength was evaluated using K9/5 Yanagi. The peeling speed was 10 strips/min. ■ High-temperature water resistance test for paint adhesion The bush-covered specimen from '1' above was immersed in a 0.4% citric acid solution of 9 and 0 for 3 days, and then subjected to 180o beer using a tensile tester to determine its peel strength. k
Rated 9/5.

This test evaluated the high temperature water resistance of paint adhesion after adhesion. {3} Retort resistance test for paint adhesion Create samples with different paint film thicknesses in the same way as in {1} above, cut each into 7 pieces in length and 6 pieces in length, and cut into two pieces with different paint film thicknesses. The lengthwise ends of the specimens are overlapped by 5 willows, and 10
A nylon film of "m" was sandwiched and pressure bonded under the same conditions as for "m" above.

This test piece was made into one shape, rolled into a semicircle shape with a radius of about 10 degrees like a circular can body, and fixed at both ends.
The presence or absence of peeling after aging for 2 and 3 hours in a 3,000 liter retort pot was expressed as the number of peeled pieces per strip. '4} Paint adhesion after processing A sample coated on one side with the same paint as in {1} above was used as the first sample.
Table * Number of pieces to be peeled/number of samples 125 Punch out a disc after the ribs, deep draw it using a punch with a side diameter of 83 so that the painted surface is the outer surface, form a cup, and cut the center of the side wall surface to the circumference. An adhesive specimen similar to '1' above was prepared so that the painted surfaces adhered to each other, and evaluated by the same paint adhesion test as in {1} above.

Claims (1)

[Claims] 1.1 to 1 on each side of the tin layer on both sides of the steel plate.
After forming a nickel layer of 100 mg/m^2 and subsequently melting the tin layer, electrolytic chromic acid treatment was performed, and 1
A method for producing a bright tin-plated steel sheet with excellent paint adhesion, characterized by forming a metallic chromium layer of 0 to 100 mg/m^2 and a hydrated chromium oxide layer of 5 to 30 mg/m^2 in terms of chromium. .