JPS6029484A - Surface treated steel sheet for can making having excellent seam weldability - Google Patents

Abstract

PURPOSE:To provide a titled steel sheet having excellent resistance to corrosion by painting and resistance to rusting by providing an Ni-Fe alloy coating layer on the lower layer of both surfaces of a steel sheet, providing an Sn coating layer on at least one surface of the upper layer thereof and forming further a Cr treating layer on both surfaces. CONSTITUTION:An Ni-Fe alloy coating layer is provided on the lower layer of both surfaces of a steel sheet and an Sn coating layer is provided on at least one surface of the upper layer of said coating layer and thereafter a Cr treating layer is formed on both surfaces to obtain a surface treated steel sheet for can making having excellent seam weldability. The Ni-Fe alloy coating layer of said steel sheet on the inside surface of the can is coated at 10-500mg/m<2> and the Fe is incorporated therein at 10-80wt%. The Sn coating layer to be provided on the upper layer thereof is preferably coated at 100-2,500mg/m<2>. The Ni-Fe alloy coating layer on the outside surface of the can is coated at 100- 1,000mg/m<2> and the Fe is incorporated preferably thereon at <=50%. It is possible not to provide the Sn coating layer thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a surface-treated steel sheet for can manufacturing, which is used as a material for can manufacturing, and particularly has excellent seam weldability.

(Prior art) Electrolytic Sn-plated steel sheets (hereinafter referred to as tin plate) and electrolytic chrome-plated steel sheets (hereinafter referred to as T
It is called FS-CT. ), and when these are used to make 3-piece cans (cans whose body consists of 3 parts, the bottom and bottom of the can, and the can body), in the case of tinplate, soldering is required. In the case of TFS-CT, an adhesive method has been mainly used. However, in recent years, seam welding methods have been used as an alternative to the "Hantai" method and adhesive methods.

When seam welding is used as the can body joining method,
The main material used is tinplate, and TFS-CT is not common because the metal chromium, chromium oxide, etc. on its surface have a high melting point, and this surface layer must be polished off before seam welding.

However, the cost of tinplate is high due to the rise in the price of Sn, etc., and there is a desire to develop a new material with low cost and high performance that can replace tinplate as a material for seam welded cans. People have already applied for a special patent application in 1982-7.
3795.55-77015.55-77017.55
-111040 and patent application No. 513-12907? proposed a surface-treated steel sheet in which a chromate treatment layer is formed after coating the steel sheet with Ni or Ni-Zn alloy. The chromate treatment layer plays a very important role in improving the corrosion resistance of these Ni-based coated steel sheets, but it is difficult to achieve a balance between corrosion resistance and seam weldability as a material for can manufacturing, and the amount of chromate treatment is small. The seam weldability is good, but the corrosion resistance is poor; conversely, if the amount of chromate treated is too large, the corrosion resistance is good, but the seam weldability is poor. The current situation is that in the old thread-coated steel sheets currently on the market, paint corrosion resistance, especially sulfide blackening resistance, is sacrificed to ensure seam weldability.

That is, when industrially producing these Nl-based coated steel sheets, it is necessary to always satisfy both corrosion resistance and seam weldability.

(4. Purpose of the invention) The purpose of the present invention is to solve this problem, and as a result of the inventor's intensive research, it has been found that N
By layering Sn, which is effective for seam welding, as a single coating layer after providing an i-Fe alloy coating layer,
It was discovered that even with an extremely low Sn coating layer of 2,500 mg/m' or less, a surface-treated steel sheet for can manufacturing that does not cause deterioration of seam weldability and has excellent paint corrosion resistance was completed, and the present invention was completed. This is what I came to do.

(Structural tension effect of the invention) That is, the present invention provides a Ni-Fe alloy coating on both sides of a steel plate, and superimposes a Sn coating on at least one side,
In addition, this is a surface-treated steel sheet for can making that has a coating structure in which Cr treatment layers are formed on both sides, and by using a Sn coated multilayer surface on the surface corresponding to the inner surface of the can after can manufacturing, it has excellent paint corrosion resistance, especially seam weldability. It is used as a material for making cans.

The present invention will be explained below.

First, the Xl-Fe alloy of the present invention is typically made of Ni-
Although it is a Fe binary alloy, Co, Cr, Sn, Cu,
It also includes cases where P etc. are contained.

The surface of the steel plate does not need to have the same plating layer, and the amount of coating may be different on the front and back sides. For example, the surface corresponding to the outer surface of the can after can manufacturing may be coated with only a Ni-Fe alloy or a single layer of N1 without overlapping the Sn coating.

This is because the characteristics required for the surface that becomes the inner surface of the can and the surface that becomes the outer surface after can production are different, and the surface that becomes the inner surface of the can after can production is the surface that comes into direct contact with the contents. It is necessary to satisfy characteristics such as paint corrosion resistance, in other words, prevention of Fe elution from paint defects, etc., and so-called under-paint corrosion performance such as sulfide blackening. This is because it is sufficient as long as the rust resistance and the aesthetic appearance after painting and printing are satisfied, and it is sufficient that the seam weldability as a whole is good.

Although the Ni--Fe alloy coating method is not particularly limited, an electric alloy plating method can be used and is economical. As for the plating bath, any known plating bath can be used, and there is no particular limitation.

Ru. As mentioned above, the surface that becomes the inner surface of the can after can manufacturing is required to have excellent coating corrosion resistance, etc., and conventionally, 250hg/m per side
'A super Sn plating coating was required. However, S
Since n is expensive, it was believed that if the amount of Sn plating was reduced to 25,001 g/m'' or less in order to reduce costs, the corrosion resistance of the coating and the seam weldability would deteriorate, making it unusable for practical use.

The present inventor conducted research to ensure coating corrosion resistance and seam weldability as a can manufacturing material using ultra-thin tinplate with a thickness of 2500II1g/m' or less per side, and found that Fewt% was After coating 10-80wt% Ni-Fe alloy coating at 10-500mg/rrf per side, apply Sni$ coating at 100-2500II1g/r per side.
n′ coating and further reflow treatment, or as it is as T-Cr (total chromium amount) using the usual method,
By forming a chromium treatment layer of 2 to 30II1g/m' per side, the Sn coating amount can be reduced to 2500f per side.
It has been found that even in the extremely thin plating region of fig/rn' or less, excellent paint corrosion resistance and seam weldability are achieved.

11f! -, 11-1+MaJ, WIl+enc'++
-/11, --Chinodo [1=d1C4 Riki's problem is that, as mentioned above, the plating layer has insufficient coverage of the base metal,
Due to poor paint corrosion resistance and heat treatment during paint baking, alloying between the Sn layer and the base metal progresses, especially when
In the Sn layer below 0 mg/lrf, almost all Fe-
This resulted in a Sn binary alloy, resulting in poor seam weldability.

However, when Sn plating is performed after coating a steel plate with a Ni-Fe alloy as in the present invention, a dense Ni-Fe alloy coating exists on the base steel and has a small galvanic effect with the base Fe. Therefore, 2500mg/rr per side
Even if the amount of Sn plating is less than f, the coating corrosion resistance is good. Also, even if the amount of Sn plating is less than 500mg/rn' per side,
When the Ni-Fe alloy coating layer undergoes heat treatment during coating film baking, S
The alloying of n with Fe is suppressed, and the unalloyed so-called Fre
It seems that e Sn W can be secured.

Free Sn FAF is particularly effective for seam weldability, so even if the amount of Sn plating is thin as in the present invention,
If Free Sn is present in sufficient amount even after the paint is baked,
Advantageous for seam weldability.

In addition, after can manufacturing, Fe in the Ni-Fe coating layer on the inner surface of the can
It is desirable that the t% is 10 to 80 wt%; if it is less than 10 wt%, it will have a character similar to that of a single Ni layer coating, and the alloying reaction with the Sn layer will increase, and if it exceeds 80 wt%, it will have a character similar to that of the base Fe. In particular, even if Sn coating is further applied,
If the coating amount is less than 2500 mg/rn' per side, the corrosion resistance after coating will deteriorate. Also, the amount of Ni-Fe alloy coating is 10
No effect was observed below mg/m'; 500 mg/m
'At super-high levels, the effect becomes saturated and the cost increases.

Next, the surface that will become the outer surface of the can after can manufacturing will be explained.

As mentioned above, the surface that becomes the outer surface of the can after can manufacturing only needs to satisfy the rust resistance after can manufacturing, and is not necessarily required to have a Sn coating layer like the surface that becomes the inner surface of the can after can manufacturing. Of course, in the present invention, a similar coating structure in which both surfaces are coated with Sn can also be used.

After can manufacturing, the surface that becomes the outer surface of the can is not coated with Sn, and Ni-F
When using only a single layer of e-based alloy coating, the coating amount of the Ni-Fe based alloy coating layer is 100 = 1000 mg/side per side.
m', Fewt% in the alloy layer is preferably 50 wt% or less, and depending on the case, a single Ni layer coating with Fewt% of 0 may be used. If it is less than +00 mg/rn', the rust resistance after painting will be insufficient, and if it exceeds 1000 mg/m', no improvement in performance can be expected, resulting in high costs.

Moreover, if the Fewt% in the alloy layer exceeds 50wt%, the rust resistance after painting will deteriorate.

After the coating layer having the above-described structure is provided on the inside and outside of the can, a chromium-treated layer is formed on both surfaces with or without reflow treatment. Chromium treatment improves rust and corrosion resistance.

Reflow processing is not an essential requirement of the present invention, and may be performed at an appropriate time. The reflow treatment also includes so-called undermelt treatment, which does not reach the level of melting the surface layer Sn.

In the present invention, there is no particular restriction on the coating method of the chromium treatment layer performed on both sides, and even if the coating method is mainly 0X-Cr (chromium oxide), such as chemical treatment of tinplate, C
MeCr (metallic chromium), 0X-C carried out in a treatment bath such as rO3-5Q42- or CrO3%a2 SiF6
Those with a two-layer structure of r (referred to as TFS-CT untreated)
However, it may be selected as appropriate depending on the required performance.

In the case of chromate coating mainly composed of 0X-Cr, such as chemical treatment of tinplate, 2mg/CrJi is added.
m' or more and 30 mg/m' or less, preferably TFS-C
Without T treatment, MeCr amount is 10 mg/rn2 or less, 0X
-Crl is 20+ng/rn' or less, T a Cr is 2mg/m' or more 30mg/m', same as chemical treatment.
m' or less is preferable. If T*Cr is less than 2 mg/m', corrosion resistance deteriorates, and if it exceeds 30 mg/rrf, seam weldability deteriorates.

After the above-mentioned coating, oil is applied in the usual manner to prevent rusting during transportation and storage, and then the product is made.

Next, an example will be described.

Example 1 Ni was applied to both surfaces of a surface-cleaned cold-rolled steel sheet under the conditions shown in (1).
- Fe binary alloy coating with electroplating method of 100% per side
mg/m' (Ni 70 to 80 wt%) and then coated on both sides of the coating under the conditions shown in (2) at 850% per side.
A Sn coating of mg/m' was applied. After that, (3) and (
4) Electrolytic chromic acid treatment was applied to both sides under the conditions shown in 4), and an oil film of dioctyl sebacate was applied to each side.
/rrf was formed and subjected to various tests.

(1) Bath composition NiSO4Fist6H2015o~200g
/ Sentence N1CQ240~80g/fL F[! SO4・7H20+o~15g/1)1. , B
O340~5'Og/1 Bath temperature 50°C Cathode current density 10A/dI112 (2) Bath composition Tin sulfate 20~30g/standing phenolsulfonic acid (65% solution) 25~35g/Bath temperature 50°C Cathode current Density 15A/dco2 (3) Bath composition Na2 Cr207 20-30g/
1 Bath temperature 40-70°C (4) Bath composition CrO350-150g/lH2SO
4 or Na2 S+F, 3-5g/x Bath temperature 50°C Example 2 In place of bath (1) in Example 1, the following bath (5) was adopted. S
The electrolytic chromic acid treatment after n coating was performed only in (3) of Example 1. Other details were the same as in Example 1.

(5) Bath composition N1Cij280~xoog/FeC
Q2 10~20g/n K4 P2O7100~150g/1 Bath temperature 50℃ Cathode current density 10A/dm2 Example 3 In Example 1, the old-Fe binary alloy coating was replaced with the former (
Under the conditions of 1), the surface that will become the inner surface of the can after can manufacturing is 100% per side.
rng/m' (Ni70~80wt%), 800mg/m' (Ni70~80wt%) per side for the outer surface of the can after can manufacturing.
80 wt%), only on the surface that will become the inner surface of the can after can manufacturing.
850mg/rrf per side under the conditions of Example 1 (2)
The surface that will become the outer surface of the can after can manufacturing is not coated with Sn multilayer coating, and both surfaces are coated with Sn of Example 1 (3) and (4).
Example 1 except that electrolytic chromic acid treatment was performed under the conditions shown in
It was carried out under the same conditions. The evaluation test was conducted on the outer surface of the can after the can was made. The inner surface of the can is the same as in Example 1.

Example 4 After the Sn multilayer coating in Example 1, a so-called reflow treatment of heating at 270° C. for 3 seconds was performed as surface Sn melting treatment. The electrolytic chromium treatment was carried out only in (3) of Example 1. Other conditions were the same as in Example 1.

Comparative Example 1 In Example 1, the Ni-Fe binary alloy coating (1) was omitted. Other conditions were the same as in Example 1.

Example 5 In Example 1, the following bath composition (8) was adopted as the Ni-Fe binary alloy coating, and the Fewt% in the Ni-Fe binary alloy coating was set to 1θ% or less. The electrolytic chromic acid treatment was performed only in (3) of Example 1. Other conditions were the same as in Example 1.

(6) Bath composition NiSO4-6H20150-200g
/text NiCu2 40-60g/textFeSO4” 7H201-2g/fLH3B0340
~50g/bath temperature 50°C Cathode current density 10A/dm2 Example 6 In Example 1, the following (
7) was adopted, F in the Ni-Fe binary alloy coating was
evt% was set to 80% or more. The electrolytic chromic acid treatment was performed only in (3) of Example 1. Other conditions were the same as in Example 1.

(7) Bath composition N15O+ a6H20+00~150
g/ lNiC9□ 40-60g/SeeFeSO4・7H,080-80g/IH3B034
0 to 50 g/bath temperature 50°C Cathode current density 3 to 5 A/dm2 Example 7 In Example 1, the Ni-Fe binary alloy coating amount was set to 5 mg/m' per side. The electrolytic chromic acid treatment was performed in Example 1 (
3) only. Other conditions were the same as in Example I.

Example 8 In Example 1, the Ni-Fe binary alloy coating amount was set to 40 omg/rrf per side. The electrolytic chromic acid treatment was performed only in (3) of Example 1. Other conditions were the same as in Example 1.

Example 9 Ni-Fe on the surface that becomes the outer surface of the can after can manufacturing in Example 2
Binary alloy coating amount is 80mg/rn' (Ni7
0 to 80 wt%). Electrolytic chromic acid treatment is Example 1
(4) only. Other conditions were the same as in Example 2.

As the above-mentioned examples of the present invention, comparative examples, and conventional examples, ordinary tin plate (#2S
It is called ET. )Also, the amount of metal Cr per serpentine surface is 100 vag
The following evaluation test was carried out on a chromium-plated steel sheet (referred to as TFS-CT) with oxidation Cri of 15 mg/m' and oxidation Cri of 15 mg/m'.

The test items (A) to (E) shown below were conducted and their performance was evaluated.

(A) UCC (Undercut Film Corrosion) Test An epoxy phenol paint for can making was applied to the test surface of the sample to give a dry weight of 50 mg/d, z per side, and baked at 205°C for 0 minutes. 180°C
There was a vacancy of 20 minutes. Then, scratch the painted surface with a knife, immerse it in a corrosive solution (1.5% citric acid - 1.5% table salt), and heat it to 50°C while bubbling CO2 gas.
After holding for 3 days, the scratched area was peeled off with tape, and the peeling state of the paint on the scratched area and the pitting of the scratched area were evaluated.

The coating film peeling status was evaluated as 0: no peeling, ○: small peeling, △: slightly large peeling, ×: large peeling, and the perforation corrosion status: 0: no peeling, O: small, Δ: slightly dogged, and X: large.

(B) IN sulfide blackening test A test specimen coated with the same coating as in (A) was made with a 4 mm overhang in the center using an Erichsen tester, and the specimen was placed in a commercially available can. After repacking the wooden barrel, 1
A rinsing treatment was carried out at 25° C. for 9 minutes. After slow cooling, the can was opened, and the state of blackening on the surface of the Erichsen ridged portion and the non-Erichsen ridged portion (flat plate portion) was visually determined. The evaluation was 0: no black change, O: small, Δ: slightly large, and X: large.

(C) Paint film secondary adhesion test A specimen coated with the same coating as in (A) was immersed in 3% saline solution and retorted at 125°C for 80 minutes.
Judgment was made by making gobbles at 2 mm intervals on the coating film with a knife and peeling off the tape. The evaluation was as follows: O: no peeling, O: small, Δ: slightly large, and X: large.

(D) Thread rust resistance test A specimen coated with the same coating as in (A) was scratched with a knife, and the center of the specimen was made a 4mm overhang using an Erichsen tester, and then tested using a salt spray test FF7II machine. 5%N
aC1 was sprayed for 3 hours.

After washing and drying the specimen, roll the ball 3'8'O1 wet bulb 35
．． The specimen was placed in a constant temperature tester at 5° C. and 85% relative humidity and left for 14 days. The thread rust resistance was evaluated by visually determining the occurrence of thread rust in the scratched portion of the paint film of the specimen. The evaluation was as follows: @no thread rust, little O, slightly large Δ, and large X.

(E) Seam weldability test After forming each specimen into a can body, using a seam welding machine,
Can body joint lap width Q, fimm, pressing force 50kg
, seam welding was performed under conditions of a secondary side welding current of 4.5 KA. The strength of the seam weld was determined by an impact test and a pulling test in which a V-shaped notch was inserted into the weld and pliers were inserted, and the appearance of the seam weld was visually determined based on the presence or absence of exfoliation. The specimens used in the seam weldability test were not coated, but only subjected to a vacuum treatment at 210° C. for 20 minutes. Judgment of strength is 0: All materials are broken, △: Some welds are broken, × Welds are broken, and appearance is: 0: No scattering at all.
○ Small scattering, △ Slightly large scattering, and X Large scattering.

The above test results are shown in Table 1.

As shown in Table 1, Example 1 exhibited good performance in all respects, and in particular, seam weldability was stable and excellent.

On the other hand, Comparative Example 1 is a so-called ultra-thin Sn-plated steel sheet that omitted the Ni-Fe binary alloy coating, and is inferior in corrosion resistance and seam weldability, and Example 5 is an example in which the Fevt% is low. However, it has poor seam weldability. Example 6 is an example in which the Fewt% is large, and the corrosion resistance and seam weldability are poor, and Examples 7 and 8 are examples in which the Ni-Fe binary alloy coating is small and large, respectively, and the corrosion resistance and seam weldability are poor.
Seam weldability is poor. Example 9 is an example in which the amount of coating of the Ni-Fe binary alloy on the surface that forms the outer surface of the can after can manufacturing is small, and both rust resistance and seam weldability are poor.

(Effects of the Invention) As described above, the present invention provides a material for seam welding cans, which has stable corrosion resistance, rust resistance, and good seam weldability due to the multilayer coating of the Ni-Fe binary alloy coating layer and the Sn layer. This is a surface-treated steel sheet for can making that has excellent properties.

/ Procedural amendment dated August 16, 1980 Kazuo Wakasugi, Commissioner of the Patent Office 1, Indication of this case Patent Application No. 137 of 1988? ElO No. 2, name of the invention, surface-treated steel sheet for can manufacturing with excellent seam weldability 3, relationship with the amended case Patent applicant address: 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name (6)
65) Nippon Steel Corporation Representative Takeshi 1) Yutaka 4, Agent 103 Address 2-2-1-5 Nihonbashi, Chuo-ku, Tokyo Date of amendment order Voluntary action 8 Contents of amendment (1) Specification No. Page 8, line 9, “This will increase costs.

" is corrected to "It increases the cost and also deteriorates the seam weldability."

(2) Table 1, page 20, Example 8, Ni-Fe alloy coating, plating amount mg/m' column, r 400J was changed to r 80
Correct it to 0J.

Agent: Patent attorney Masao Igami

Claims (3)

[Claims] (1) Provide a Ni-Fe alloy coating layer on the lower layer on both sides of the steel plate,
A surface-treated steel sheet for can manufacturing having excellent seam weldability, characterized in that a Sn coating layer is provided on at least one side of the upper layer of the Ni-Fe alloy coating layer, and a Cr treatment layer is further formed on both sides. (2) The amount of Ni-Fe alloy coating layer on the inner surface of the can is 1
0 to 500II1g/m', the Fe content in the coating layer is 1
0 to 8 wt%, and the coating amount of the Sn coating layer provided on the coating layer is 100 to 2500 mg/rn'. (3) The coating amount of the Ni-Fe alloy coating layer on the outer surface of the can is 10
0 to xooomg/m', the Fe content in the coating layer is 50
wt% or less, and the steel plate according to claim 48, wherein the Sn'$ coating layer is not provided on the coating layer.