JPS60103200A - Tin-free steel having excellent adhesive properties - Google Patents

Abstract

PURPOSE:To obtain economically a tin-free steel having excellent resistance to retort treatment by specifying respectively the S/O value and the value of an alkali soluble component in a chromium hydroxide film in the stage of subjecting a steel sheet as an anode to a reverse electrolysis after Cr plating then further to an electrolytic chromic acid treatment. CONSTITUTION:A thin steel sheet is cathodically treated in an aq. soln. congt. Cr, for example, an aq. sulfuric acid soln. contg. CrO3, Na2SiF6, by which electroplating consisting essentially of metallic Cr is accomplished. The electroplated steel sheet as an anode is in succession thereto subjected to a reverse electrolytic treatment in an aq. soln. contg. Cr. The thin steel sheet after the reverse electrolytic treatment is subjected to an electrolytic chromic acid treatment in an aq. soln. contg. >=1 kind of CrO3, K2Cr2O7 and dichromate. The S/O in the hydrated chromic oxide film on the surface of the tin-free steel (TFS) obtd. in this case is regulated to >=1.8 and the alkali soluble component to >=30%, respectively, by which the TFS having extremely high adhesive properties is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides tin-free steel having a lower layer of metallic chromium and an upper layer of chromium-water ol-thorhombide on the surface of a steel plate, which has excellent retort treatment resistance, especially as a paulownia material for adhesive cans. W
, concerning Koriya mate-treated steel.

'tiL%/41 chromate-treated steel sheet is called tin-free still chrome type (hereinafter abbreviated as 'rFS), and is known for its 9!f properties as a material for cans that can replace tinplate. Its usage has been increasing in recent years.T F S
The surface of the can body is coated with metal chromium and water UGH chromium), so it does not have sufficient welding performance because it has a high IQ, and when making cans, the can body is coated with epoxy, phenolic and J resin, and then nylon is used. It is joined with adhesive.

Recently, the use of T F 8 cans has expanded, and the contents such as charcoal drinks and beer can be filled at low temperatures! IJ- (not only hot bags, but also so-called pot punk bags or bags in which contents such as fruit juice and coffee are heated and filled) As it has come to be used for cans that require retort processing, problems have arisen in which the can body breaks.

The tear in the can body that occurs in the TFS shoulder can due to this hot pack and retort treatment is caused by the hot water penetrating through the nylon adhesive of the joint ff18.
Love the adhesion at the interface between W and TFS <7. c, coating film-1
'This occurs due to separation from the FS interface.

In order to obtain ``I'' FS with excellent adhesion, a lot of research has been carried out, and the sulfuric acid added to the chromium plating bath or the chromium glare bath is eutectoid in the hydrated chromium film. , 4 contained in the chromium hydrated film is believed to be eluted during retort treatment and cause peeling at the coating IIA-'I' FS interface.
Products that use fluoride ions to reduce A-power as much as possible (for example, JP-A-57-5344 (1° JP-A-56-1)
42897) has been proposed.

However, in order to do this, it was necessary not only to add sulfuric acid to the chromium plating bath, but also to add fluorine to the chromium plating bath. A method of adding a compound has been adopted, but in this case, the precipitation efficiency of all the chromium compounds is poor, resulting in a significant decrease in manufacturing efficiency, and the resulting TFS has frequent surface stains, which impairs the quality of the product. However, the inventors of the present application devised a method to solve this problem, which is called chromium plating in γ. After plating,
We proposed to perform a reverse FJJ solution using a steel plate as an anode in the solution, and to perform a chromic acid treatment in an aqueous chromium solution without adding sulfuric acid.
-277998). However, after investigating the bales, it was discovered that this method of inserting a reverse fermentation process using steel as an anode between the chromium plating process and the chromic acid treatment process improved paint adhesion. Although C4i has a strong C4i effect, the growth of chromium water A11 oxide film in the subsequent electrolytic chromium cleaning process is suppressed in the steel plate after reverse electrostatic discharge, showing excellent paint adhesion. 1-'l'E'
In order to stably obtain s, a large amount of chlorine and blood is required in the chromium vinegar treatment process, and it has been found that it is not economical.The present invention solves the above-mentioned situation. It was done after seeing a lot of things,
The object of the present invention is to provide a '1'P'S that can be produced economically and efficiently and has extremely good retort resistance.

In the present invention, metal chromium plating is applied to a thin steel plate at a thickness of 50 to 200 cm/d, and the metal chromium-enhanced surface is coated with 5 to 30 μm/d.
Regarding TFSK with a chromium hydrate coating of /d, the metallic chromium layer has poor corrosion resistance at less than 50~1rrl. Since further improvement cannot be expected, normal TFS
has a metallic chromium layer of 50-200 +v/1. - If the chromium hydrated oxide film has a droplet of 5 Tη/ze, the desired paint layer density cannot be obtained;
If the amount is more than yrl, the appearance will deteriorate and the chromium water U oxide film will crack during processing, making it impractical.

Furthermore, chromium slag 1" enemy monster hit 1 knowledge is 8-25
η/d is most desirable.

The inventors of the present application previously proposed a method for producing TFS with excellent paint adhesion, by chromium plating in a chromium plating bath to which sulfuric acid was added, and then performing reverse electrolysis to make the steel plate positive in the solution.
Next, he proposed electrolytic chromic acid treatment in an aqueous chromic acid solution without sulfuric acid (+!j Kaisho 57-1779).
(See No. 98). Therefore, this method of inserting a reverse electrolytic application process as a steel plate anode between the chromium plating process and the chromic acid treatment process is effective for producing TFS with good paint VB layer properties. However, in the steel sheet after reverse electrolysis, the growth of the chromium hydroxide film in the subsequent electrolytic chromic acid treatment process is suppressed, and the T.
In order to maintain stable FS44), a large amount of electricity is required in the electrolytic chromium cutting process11). The reason for this is not clear, but it is thought that the properties of the surface layer of the steel sheet were deteriorated by the reverse electrolytic treatment in which the steel sheet was used as an anode after chromium plating.

The Genmyojaji of this application has a taste in the characteristics of the surface of the chromium-plated steel plate that has been altered by this reverse electrolysis, and also has eutectoid properties in the chromium slag 1'' oxide film regarding the VC layer properties of the TFS paint can. I had doubts about the conventional theory that the sulfate root is the title, and chrome plating → energization → ``The frustration of the customers who manufactured the process of 1m chromium enemy treatment in the company-f4ttY has 'I''
For F S, +m=I retortability and water o11
We quantitatively investigated the relationship between the S content of the chromium oxide film and the alkali Irn content.As a result, it was found that hydration is It has been discovered that a chromium oxide film in which S10≧0.18 and alkali soluble content≧30 can provide extremely excellent adhesion, leading to the creation of the present invention.

The test method for retorting resistance, the method for measuring the water-to-water ratio and the alkali-soluble content in the wolfberry chromium dioxide film, which were used to understand the quality characteristics of TFS, were as follows.

(1) Apply 60 mf/drrl of phenol-epoxy paint to the sample surface 1 of retort processable 'r iL''S, and apply it at 210℃ for 1 hour.
Bake for 2 minutes. Apply the same paint 2 to another sample surface 2.
It was applied at a rate of 5 my/dm' and baked under the same conditions. These two samples were each cut into pieces of 70 m wide and 60 m long, and two specimens with different coating thicknesses were cut at both ends in the length direction (IA and 2
A) Layer k 8 w and cover the song with 100 μm nylon film 3 (adhesive) fK: preheated at 200°C for 120 seconds using scissors and a hot press, 3
Layering was carried out at 2()0° C. for 3() seconds under a pressure of Kg/cri (see Figure 1a). Ten sets of these test pieces 4 were made, and after pre-rolling them to about 1011 rrus like a can body, they were fixed to an angle 5 with a base of 70 rpx as shown in Fig. , 1.
The presence or absence of peeling after 300 minutes in a retort pot of 6 to 1.7 k,y/~ was observed. IO+hi
The index of retort treatment resistance and C by the number of strips in i
7. 6.1-The lateral force f is traced as follows.

・・・Jdkon (L number (1/
To 1.0 lines...〃 1 to 2/I (1 line x... 〃 3 or more/10 lines (21810 ratio d (11 constant i' F
Mosquito 4ii! The three-dimensional Ik of
As shown in Figure 2, the intensity ratio of the 20 yellow peak and the 11 yellow peak on the AES chart is determined by
The value of 0 is set to 1.
．． OXl 0-9torr, beam pressure 10.
One by one at OKV. :. In order to perform depth analysis, A
1-sputtering force 1] I4・ton u= 4. o KV,
Mountain, flow rate 0.6μA/trX, J'% S'-I
f 2.2 S in the model conducted at xlo-7torr
/ , 0 in the I-shape direction takes its maximum value slightly inside the M surface (at a depth of about 10 mm). In the present invention, this maximum value was defined as the S10 value of each sample.

(3) Alkali-soluble molecule FS After nitriding at 210℃ for 12 minutes, 7.5N
- Na1l (110°C for 10 minutes), and the amount of chromate coating dissolved at that time was divided by the original amount of chromate coating. For those with a larger value of 11, the chromate coating was insolubilized by dry baking. I will show you something difficult.

When manufacturing the TFS of the present invention, a Y steel plate is degreased in-situ using a conventional method, washed with water, and then dried in an acid bath to obtain Cr0310 (
)~2 I) OP/l, 1(2S(J4 (1
5-1t/l.

Cathodic treatment was performed in a chromium plating bath having a composition of 65 to 8 f/l Na2SiF, followed by M? Reverse electrolytic treatment is carried out using a steel plate as an anode with an electricity amount of 0.3 to 9 C/dm', and after washing with water, waterless ROM sales: 30 to 9
(l t/13,6tt acid 0.03-0.9ill,
The steel plate was treated as a cathode in a tuna cream acid solution prepared at 10°C.

The amount of hydrated electrified chromium removed formed on the surface of the obtained 'r F S is determined by
Fluorescent X-ray segment of surface chromium before and after melting operation in Ii)
It was detected by tr, and the d-decomposition h was defined as water AL1 supported chromium i (t).

The samples used were chromium plated, m, 1p (metallic chromium after adjusting the amount of electricity during chromium treatment with Ii4) 0~
120 thy/m', water * chromium content 1o-2
0ノ〃y/y(” was kept in the A11 box.

Figure 3 shows the T FSO resistance resistance process tested.
Mizuo IJ f'i S / f 34 of the black tribe" d
and alkali soluble content. S10 value is 0.18
As mentioned above, the alkali soluble content is in the range of 30% or more/
It can be seen that the retort resistance (11) is extremely excellent in cases where membranes are ruptured.

Because the above rice milling process was reverse electrolyzed as a chrome plate, the chromium hydroxide film was It has been found that if the S/C1 value in the coating is 0.18 or more and the alkali soluble content is 30 or more, the multilayer property during coating can be maintained at an extremely good level.

According to many research results that have been published so far, the sulfur base that coexists with chromium hydroxide generally affects the retortability, and also contributes to the insolubilization of the chromium hydroxide film during burnout. It was a common belief that the Alka'J al bath content, which is an indicator of grain size, impairs retortability.

In 1P'S, which uses a reverse 'tL W4 process in which a steel plate is treated as an anode between the chromium plating process and the electrolytic chromic acid treatment process, a certain amount or more of both 4JT
(Iff) It has been discovered that the presence of acidic radicals actually improves the retort resistance, and also produces a product that has better properties than the conventional one in terms of 1ml durability when retorted at still temperature. Although the details of the improvement mechanism are not clear, the reverse electrolytic treatment after chromium plating causes the hydrated chromium oxide film shown in Table 11 of the steel plate to become seismic.
During the subsequent electrolytic chromium dispersion treatment process, eutectoids (mt-rich), which are generated in the treatment bath to which sulfuric acid is added, have no effect on the performance of the film, which is difficult to insolubilize with alkali during the baking treatment, and the resulting It is considered that this greatly improves the contact properties of rP's.

υF The present invention will be specifically explained with reference to Examples and Comparative Examples.

A convex steel plate (T4CA) with a thickness of about 0.22 was heated at 80℃ in a pomerin bath, and with a density of 10
Electrolytic degreasing was performed for seconds, and after washing with water, 10% [5 in 2804]
After dipping for a second and washing with water, the main treatment was performed under the following conditions. This process consists of (1) chrome plating process → (2) reverse electrolytic treatment process → (3) army j tampering ROM modification treatment Ill+ of IA'A
't is bamboo, (1) and (2) are the same '+44,) 1 Jlu of fruit is continuously washed in the liquid, and between (2) and (3) and after (3) is finished, it is washed with water. No.

(1) Chromium plating plating solution composition Cr(J3 150 f/eHzSO4
(1,3-1,Oy/(I Na2SiF6 7 t/11 Plating conditions Liquid temperature 50℃, rli flow V'j'j Ij
J451+ A/d m' with a shade width JV, Treatment (2) Reverse electrolytic treatment Reverse electrolytic treatment was performed at 0.5 to 4 coulombs/d m' using the steel plate as an anode. For comparison, Table 1 also shows an example in which reverse voltage yjr was not performed.

(3) 1 Crazy chromic acid treatment composition CrO360f/11 H2SU4 0.05~0.6 f/lj liquid temperature 40~
What about cathodic treatment in chromium enemy baths with different sulfurization carbon degrees at 45℃? When reporting samples immediately, please be sure to check the conditions during chromium plating and electrolytic chromic acid treatment. r: The amount of metal chromium was adjusted to be 100 to 2 o omy/m, and the amount of chromium oxide per day in water was 10 to 20 μ/1n°. Table 1 shows the 11σ retort processability, the alkali soluble content of water-based chromium oxide 1, and the S/() value measured for the obtained sample O-1.

From the results in Table 1, (1) Chrome Metsugi → (2) Reverse electrolysis →
(3) In l' FS produced in the process of electrolytic ROM fermentation treatment, hydrated chromium on the surface (S/o≧0
．． It can be seen that retort treatment resistance is extremely good if the S value of 18 and the alkali d soluble content is 30 or more.

Even for TFS processed in a similar process using reverse 'It purchasing processing, the S/() value, alkali rJTY6 component force, upper i
If you are not satisfied with your own area, it is an insufficient characteristic. In addition, when the reverse electrolytic treatment is not performed, the i
Even if the hydrated chromium oxide group of FS satisfies the above range with respect to S/Of@, alkali soluble content, it exhibits significantly poor paint tightness.

Table 1

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the retort resistance test method for rlI'S paint @ lump force, Figure 2 is an AES measurement chart, and Figure 3
The figure is a graph showing the relationship between the retort treatment resistance of TFS, the S10 value of the water-omylated chromium film, and the alkaline MJ bath content. Figure 2 E (eV) Figure 3 Alkali soluble content

Claims (1)

[Claims] A thin 5III plate is cathodically treated in an aqueous solution containing chromium to perform electroplating mainly consisting of metallic chromium, followed by reverse electrolytic treatment in a chromium-containing water solution using a steel plate as an anode. Consists of acids, dichromic acid and dichromic hydrochloric acid! In tin-free steel produced by electrolytic chromic acid treatment in an aqueous solution containing 1 at or more selected from IP, the hydrated chromium oxide film on the surface contains S7 with S10≧0.18 and has a
A tin-free steel with excellent adhesive properties, which has an alkali-soluble content of 30 or more after dry firing for a minute.