JPS62297473A - Ni alloy multilayer plated steel sheet having superior corrosion resistance, weldability and paintability - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance, weldability and adhesion to paint by successively forming an underlayer of Ni or an Ni alloy, a coating layer of an Ni-P alloy and a chromate film on the surface of a steel sheet by a specified amount each. CONSTITUTION:The surface of a steel sheet is activated and plated with one or more among Ni, Ni-Co and Ni-Fe to form an underlayer by 100-200mg/m<2> per one side. The plated steel sheet is washed and an upper coating layer of an Ni-P alloy is formed on the underlayer by 10-300mg/m<2> per one side. A chromate film is further formed on the upper coating layer by 3-50mg/m<2> (expressed in terms of metal Cr) per one side. The Ni alloy multilayer plated steel sheet has superior corrosion resistance, weldability and paintability, so it can be used as a material for an electric resistance seam welded can, an easy opening can top or the like, after painting.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention provides corrosion resistance, weldability by electric resistance welding, χp'
%, -a This relates to a multilayer Ni-based alloy plated steel sheet that has excellent packaging performance and is used as a material for various containers such as beverage cans and general cans.

(Prior Art) In recent years, can manufacturing methods and can designs for beverage cans and food products have significantly advanced and diversified, and materials for containers that are compatible with these are required to be low-cost and high-performance.

In particular, electric resistance welding can manufacturing methods, such as the nude conic welding can manufacturing method, have a high material yield, high strength during bonding, extremely low leakage rate due to poor bonding, and are suitable for design cans of various shapes. It has many advantages and is beginning to be widely used.

Conventionally, this welded can making material has a Sn deposit of 310 or more (Sn deposit 1°129/nt''), preferably #2.
Sn of 5 or more (Sn adhesion amount 0.289/rr?)
Galvanized steel sheets have been used.

However, although Sn-plated steel sheets are excellent in weldability, corrosion resistance, etc., they also have drawbacks such as those of the reverse method, and countermeasures have been desired.

In other words, when using painted Sn-plated steel sheets, the paint adhesion, especially the paint adhesion (so-called secondary paint adhesion) when the building is left in a corrosive environment for a long time after painting, or the corrosion resistance after painting are not necessarily sufficient. There were some shortcomings such as:

In addition, in the welded parts of Sn-plated steel sheets, the Sn-plated layer is melt-bathed or only a small portion of the Sn oxide layer exists, and there is almost no Sn-plated layer, so it is difficult to apply painting. However, the corrosion resistance cannot necessarily be said to be sufficient.

In recent years, due to the development of coating technology, there is a tendency for painting methods to be adopted for high-temperature and short-time baking, but
If high-temperature paint baking is carried out at 0.degree. C., the Sn plating layer (melting point of Sn is 231.degree. C.) is melted, and a coating film with excellent coating performance cannot be obtained.

Recently, various steel plates in which the Ni plating layer is treated with a chromate coating have been developed as materials for containers in place of Sn-plated steel sheets, especially as materials that can be made using the electric resistance seam welding method. For example, ``
``Steel plate with Ni diffusion treatment layer and chromate coating layer on the surface of the steel plate'' JP-A-56-169788 Steel plate with Ni plating layer and chromate coating layer, JP-A-59-2
There is a steel plate etc. in which a chromate coating layer is applied after providing a Ni diffusion layer and a Ni plating layer as disclosed in Japanese Patent No. 32296.

These steel plates have a wide suitable welding range and also have excellent coating performance, and are used as materials for containers, mainly for welded cans.

(Problems to be Solved by the Invention) However, when these steel sheets for containers are examined in detail, it is found that although the Ni plating layer and the Ni-Fe diffusion layer have a melting point lower than that of the steel sheet, they have a considerably high temperature. Since the contact resistance value is also large, there is a problem that it is difficult to achieve sufficient welding strength and a wide welding range without welding defects (occurrence of splintering).

In addition, Ni metal has very good corrosion resistance, but
Compared to a steel plate, its potential is cathodic (noble), so
Depending on the type of can contents, perforation corrosion may occur from plating defects, so there is a problem in that the contents of the can must be limited.

On the other hand, easy-open can lids do not require a can opener.
It is used in almost 100% of beverage cans because it can be opened easily anytime and anywhere.

It is thought that this technology will be used in all food cans in the future.

Currently, M plates are often used as materials for easy-open can lids due to their excellent can-opening properties, and surface-treated steel plates (tinplates) are used for foods where M cannot be used (for example, tomato juice, etc.) due to their corrosion resistance. (foods containing salt). However, as a result of recent studies in terms of steel plate materials and can lid design, it has become possible to manufacture easy-open can lids made of tin plates that have can opening properties comparable to M plates, and new materials are required to further reduce can prices. It became like that.

Easy-open can lids have a V-shaped notch on the surface to make opening the can easier and to open a mouth large enough to drain the contents. Strict processing is performed, such as overhanging, drawing, caulking to fix the tab in that area, and so-called rivet processing.

Therefore, for easy-open can lid materials, not only the workability of the steel plate itself but also the following performance is required of the surface coating layer.

(a)! By J pet processing and score processing.

Cracks should not occur in the coating layer, and even if they do occur, they should not reach the base steel.

(b) Do not deteriorate the coating performance of processed parts.

In addition, it is also required to have excellent paintability and corrosion resistance after painting as a whole. In addition, can lids other than easy-open can lids and can bodies are also subjected to severe processing such as tightening, so the same characteristics as described above are required for bending parts and the like.

Conventionally #25~s75 tinplate (Sn plating amount 2 EI
OO~8400 m1ij/rr? ) etc., but tin is expensive and there is a strong demand for cheaper materials with superior performance.

(Means to Solve the Problem) Under these circumstances, the inventors of the present invention have sought to further improve the performance of materials for welded cans, and to improve the amount of Sn coating that can be used as easy-open can lids or regular can lids. With the aim of developing a material that is inexpensive and has excellent properties such as weldability, corrosion resistance, and paint adhesion as an alternative to tinplate, which has a high
They developed an alloy-based multilayer plated steel sheet. The gist is that Ni, Ni-Co alloy, Ni-F
It has a base coating layer consisting of one or two or more layers of e-alloy and has an adhesion amount of 100 to 2000 m9/i per side,
The amount of adhesion per one side on the surface is 0~300 mg/m.
2 (D Ni alloy with excellent corrosion resistance, weldability, and coating performance, which has a Ni-P alloy coating layer and a chromate coating layer with a coating amount of 3 to 5 omg/- per side in terms of metal Cr amount on the outermost layer. This is a multi-layer plated steel sheet.

(effect) The present invention will be explained in detail below.

In the present invention, thin steel sheets include tinplate, tin-free steel (T, F,
Use various cold-rolled steel sheets manufactured for surface-treated steel sheets such as S, ) that have been subjected to cold rolling, annealing temper rolling, or second cold rolling, etc., and prepared as base sheets for surface-treated steel sheets. .

Currently, steel sheets are surface-activated by pretreatment in the production of surface-treated steel sheets, that is, alkaline cleaning and pickling, followed by Ni plating and Ni plating.
-Co alloy plating, one or more layers of Ni-Fe alloy plating, or a form of Ni-Fe alloy plating, Ni-
The above-mentioned Ni and N are added to the Fe diffusion alloy layer and the diffusion layer.
Overlapping plating of one or more layers of i-Co and Ni-Fe is applied.

The plating bath and method for applying these base coating layers are not particularly specified, and include nickel sulfate-nickel chloride-boric acid bath, sulfuric acid + nickel + copal) -
It is preferable to use a boric acid bath (nickel chloride + cobalt), a boric acid bath (nickel chloride + iron), a boric acid bath (nickel chloride + iron), or a boric acid bath (nickel chloride + iron).

For example, (a) Ni plating current density: 1O-5oA/am' Plating temperature: Room temperature to 8o'C (b) Ni-co alloy plating (Ni-50%Co alloy)
Current density: 10-50 A/arl Plating temperature: Room temperature to 80'C (c) Ni-Fe alloy plating (Ni-40% Fe alloy)
Current density; 5-50A/drr? Plating temperature: normal temperature to 80°C (d) Ni-Fe alloy plating using diffusion treatment method
A previously treated layer is provided on the surface of the steel plate using an electrical method or (a Ni-saccharide additive-based aqueous solution coating method), and a Ni-Fe alloy diffusion coating layer is provided by heating and diffusion treatment. For example, a cold-rolled steel plate is A method is employed in which a Ni treatment layer is provided after the surface is subjected to a surface cleaning treatment, and a diffusion treatment is performed at a heating temperature of 600 to aOO° C. in a non-oxidizing atmosphere or a reducing atmosphere, which also serves as annealing.

These base coating layers are applied in an amount of 100 to 2000 mg/m2 per side.

If these base coating layers are less than lOOm97m', uniform coverage of the plating original plate is insufficient, and even if a predetermined amount of Ni-P alloy coating layer is provided on top of these,
The uniformity of the composite coating layer is insufficient and corrosion resistance cannot be obtained.

In addition, if the amount of the coating layer exceeds 2000 mg/m2, the effect of improving uniform coverage is saturated, and the base coating layer easily absorbs hydrogen during processing and is relatively hard, so it is difficult to tighten the coating. Processing during the manufacturing process of can containers, such as processing or riveting, may cause cranking or peeling of the coating layer, which is undesirable.

Therefore, these base coating layers have a coating amount per side of 100 to 2000/-1, preferably 1 s O-1
00o'fn9/r? is within the range of Next, one or more layers of these Nl-based base coating layers are applied, and then Ni-
Perform the upper layer coating treatment of the P alloy coating layer.

This method of providing the Ni--P alloy coating layer does not specify any plating bath composition, electrolytic treatment conditions, etc.

For example, the coating treatment is performed using a plating bath such as the following under electrolytic conditions: plating temperature: normal temperature to 80° C., current density: 1 to 50 A/dm'.

Therefore, in order to achieve the object of the present invention, the amount of the coating is heavy, and the amount of coating on one side is 10 to 300:n9.
/lr? A coating layer is provided.

Is this coating layer amount 10f/rr? If it is less than that, it will be difficult to form a uniform coating layer, and the anticorrosion effect on the base Ni-based coating layer will not be obtained, and the effect of improving weldability by the Ni-P alloy coating layer will not be obtained.

Also, the amount of the coating layer is 300 rru; 1/rr? 300 WvW.
? A large amount of electricity is required to obtain a coating layer with a coating amount exceeding 100%, which is not economical.

The Ni-P alloy coating layer has a thickness of lO~300 m9/n?
, preferably 30-100-/rr? It is.

In addition, it is desirable that the alloy composition of the Ni-P alloy coating layer has a low melting point from the viewpoint of weldability, and the P content is 3 by weight.
N with P content of ~30%, preferably 7.5-15%
It is preferable that the coating layer has an i-P alloy composition. In the present invention, after applying the Ni--P alloy coating layer, it is washed with water, and then a chromate treatment is performed in order to improve the paintability and coating performance.

1-Chromate coating improves the adhesion of can paints and prevents so-called undercutting collodion, which occurs when water (liquid content) permeates through the paint film and corrosion progresses at the interface between the steel plate and the paint film on the inside of the can. It has a big effect. Therefore, the adhesion of the coating film does not deteriorate over a long period of time, and good corrosion resistance is maintained.

The chromate coating is also highly effective in preventing blackening of the steel sheet surface, that is, sulfide blackening, which occurs in foods containing S compounds, such as fish meat and stored products. As described above, chromate coatings are effective in improving performance, especially when used as a coating, but are harmful to welding. The chromate coating referred to here refers to two cases: a single coating of water-use chromium oxide, that is, the original chromate film, and a coating consisting of two layers of water-use chromium oxide on top of which is metal Cr as a lower layer. The water-conserving chromium oxide film is an electrical insulator and has high electrical resistance, and metallic chromium has a high electrical resistance and melting point, both of which tend to deteriorate weldability.

Therefore, in the present invention, from the viewpoint of corrosion resistance, weldability, etc., the amount of Cr deposited on one side is 3 to 5 o in terms of metal chromium.
mg/m2, preferably 5-35 TrK)/rr?
The amount of Cr deposited is selected.

That is, if the amount of Cr deposited is less than 3 mtl/rr1, it will not be effective in improving paint adhesion or preventing corrosion under the paint film such as undercutting collodion, so the amount of Cr deposited is preferably 3 m9/ld or more! A coating amount of M19/m' or more is preferable.

In addition, if the amount of Cr deposit exceeds 50 mg/m2, the contact resistance will increase significantly, so it is necessary to increase the welding current, and the welding range will become narrower due to the occurrence of spatter, which will deteriorate weldability. . Also, the amount of Cr deposited is 50 mg.
/m2, the appearance deteriorates. 1. In particular, when the treated material of the present invention is intended for use in welded cans by electrical resistance seam welding, it is preferable to regulate the amount of chromate film and the structure of the film as follows.

In other words, in terms of the amount of metal Cr, the amount of metal C deposited per one side
R layer is less than 2m9/rrl, water oxidation Cr layer is 1s
mg/r? The total amount of chromate coating is below 3~20F
Consists of a chromate coating layer of +9/m'. The chromate film with this film structure limits the gold@Cr layer, which has the most negative effect on welding work, to an extremely small amount, and is composed of a hydrated oxidized Cr layer within a range that does not impair weldability. be.

Chromate treatment is performed using chromic acid, Nα+ of various chromic acids.
Any method may be used, such as immersion in an aqueous solution of ammonia salt, spray treatment, cathodic electrolytic treatment, etc., but cathodic electrolytic treatment is superior. Among these, the most excellent method is to carry out cathodic electrolytic treatment in an aqueous solution containing Cry, to which So4 ions, F ions (including complex ions), or a mixture thereof are added. The concentration of Cr01 is 20-1002
A range of μ is sufficient, but there is no need to specifically regulate it. The amount of anions to be added is 1/1 of the hexavalent chromium ion concentration.
The best chromate coatings are obtained at a concentration of 300 to 1/25, preferably 1/200 to 1150. If the anion concentration is less than 1/300 of Cr, it becomes difficult to obtain a homogeneous and uniform chromate film of good quality, which greatly affects coating performance. If it is 1/25 or more, the amount of anions taken into the produced chromate film increases, and the performance of the film deteriorates. There is no need to particularly regulate the bath temperature, but it should be between 30 and 7
A range of 0°C is appropriate from the viewpoint of workability. The cathode electrolysis current density is 5 to 1 o A/drr? is sufficient. Processing time.

In any combination of the above processing conditions, the amount of chromate deposited is 3 to 20, depending on the application, as shown above.
m9/n? Or 3-50 rn9/rr? It is set so that it falls within the range of .

In addition, in the present invention, S and the like are contained as unavoidable impurities from the chemicals, electrodes, etc. used in the treatment process of forming the Nl base treatment layer and the Ni-P alloy plating layer, but this does not interfere with the present invention. isn't it.

In addition, the plating base plate used is a base plate used for ordinary container materials, that is, a tin base plate, and a base plate for TFS.For the purpose of improving corrosion resistance, Cu is added in the range of 0.05~
Cu-containing steel plate containing 0.3o or 0.2-10%
A steel plate containing Cr, a steel plate containing 0.1-1% Cr1CNi, etc. may be used as the plating base plate.

Examples of the present invention will be described below.

Ni, Ni-Co, and Ni- shown in Table 1 were applied to the surface of a cold-rolled steel plate (As Co1d material or steel plate subjected to Furufinitsu 7 finish) that had been subjected to surface cleaning treatment.
One or two Fe undercoat treatment layers were provided.

Next, various evaluation tests were conducted on the evaluation material, which was provided with a Ni--P alloy plating layer and a chromate film treatment layer on the surface, and was further coated with oil.

A. Painting performance and corrosion resistance The dry weight of epoxy phenol (phenol-rich) paint for can manufacturing is 50 m9/drr per side.・It was applied to the test surface of the evaluation material, baked at 250°C for 10 minutes, and then baked at 180°C for 20 minutes (simulating external coating). Scratches were made with a knife, and the following evaluation tests were conducted on each.

■ As a corrosive solution for paint adhesion over time (1.5% citric acid + 1.5 titr, cl
) using an aqueous solution, conduct a immersion test at 55°C for 7 days in the open atmosphere, peel off the scratched area and flat area with tape, and evaluate the state of paint film peeling on the scratched area and flat area using the following evaluation criteria. did.

◎・・・°・°Paint peeling width from scratch area is 0.2
Less than 5mm, no peeling of the paint on the flat surface, ○...The width of the peeling of the paint from the scratch area is 0.2
5m or more to less than 0.40mm, no paint peeling on the flat surface, △...The width of the paint peeling from the scratch area is 0.4
0- or more to less than 0.60 mm or 10 points or less of the part where the paint film peeled from the flat surface ×...The width of the paint film peeled from the scratch part is 0.6
0m+++ or more or 11 or more points where the paint film peeled off from the flat surface ■Corrosion resistance after painting The above evaluation material was immersed in a 0.5% citric acid aqueous solution at 50'C in an N2 atmosphere for 12 days to determine whether the scratched area The drilling corrosion depth was measured and the corrosion resistance was evaluated using the following evaluation criteria.

◎・・・・・・Maximum drilling corrosion depth O, less than lOw++○
・・・・・・ 0.10 or more ~ 0.
Less than 15 Δ... Maximum drilling corrosion depth 0.15 ■ or more ~ 0.
Less than 20+nm X...0.
20+a+ or moreB, weldability and welding performance by electric resistance seam welding method ■ Using a Sudronik type welding machine, 0,5
A welding test was conducted with a welding lap width of m width, a pressurizing force of c2 kg, a welding speed of 3 Q, and m/min, and the appropriate welding range was determined. That is, the welding current (,) at which sufficient welding strength is obtained for the welding can and the welding current (b) at which welding defects such as splash become noticeable are measured, respectively.
(b) The current value of −(,) was taken as the welding range. In addition, the evaluation criteria were based on the following method.

◎・・・・・・Welding current range (b) −(,) is 3A or more ○・・・・・・2Å or more
Less than 3A△・・・・・・IA
More than 2 people×Less than 2 people×・・・・・・
Less than IA ■ Painting performance of the Punto part on the inner surface of the welded can A welded can was created with the inner surface of the can coated with EBOKI 7 phenolic paint at 651n9/dm' within the above appropriate welding range.The welded can was coated with 0.1% phosphoric acid. Filling with an aqueous solution, a weight having a weight of I kg is dropped from a height of 1 OO crn onto the can body from the outside surface to generate a punt part in which the inside surface of the can becomes a convex part,
After being left at 55° C. for 3 months, the condition of the Punto part was observed, and the peeling of the paint film and the corrosion under the paint film were investigated and evaluated. In addition, the evaluation criteria were based on the following method.

◎・・・No peeling of the paint film or corrosion under the paint film due to tape peeling, O・・・Slight peeling of the paint film due to tape peeling, but no corrosion under the paint film. Δ: Significant peeling of the paint film occurred due to tape peeling, and some red rust was observed under the paint film.

×・・・・・・Most of the paint film peels off due to tape peeling, or pitting-like corrosion occurs under the paint film■ Paint a 50μ thick PVC sol-based repair paint on the corrosion-resistant bath contact area of the welding area. After that, a scratch was made, and the sample was immersed in commercially available apple juice at 50°C for 1.5 months under an N2 atmosphere, and the corrosion resistance was evaluated by measuring the state of perforation corrosion in the scratched area.The evaluation criteria were as follows: The following method was used.

◎・・・・・・Maximum drilling corrosion depth is less than 0.075 wm0 ””” OoO'75 r
More than m -0, less than 1O △・・・・・・ More than O, 1Om ~
Less than 0.15 tone ×・・・・・・ O, 15m5+ or more C, Performance after EOE processing Easy open end (gog) For the purpose of evaluating corrosion resistance performance after processing, apply epoxy/phenol paint for EOE to 50 m9/ After painting, EO to become drd
E-processing was performed, and evaluation tests were conducted on the inner and outer surfaces of the can, focusing on the rivet processing section, score processing section (remaining score thickness of 75μ), etc., which undergo severe processing, and the performance after EOE processing. Ta.

■ Corrosion resistance for internal surfaces In order to clearly determine the superiority of the performance of each evaluation material, (1.5% citric acid + 1.5%
% NaCJ, water) system solution at 27°C under N2 atmosphere.
We conducted a 3-month immersion test to observe the adhesion of the paint film and the corrosion under the paint film, and conducted an evaluation.The evaluation corresponds to processed parts such as riveting and scoring. The evaluation was performed mainly on the inner surface, and the evaluation criteria were as follows.

◎・・・・・・There is no peeling of the coating due to damage such as cracks on the coating layer due to processing (peeling of cellophane tape), and no corrosion under the coating is observed. O・・・・・・Above. Similar to the above, damage to the coating layer has little effect, but although the adhesiveness of the paint film deteriorates over time and the paint film peels off with cellophane tape, there is no obvious corrosion under the paint film.

Δ: Due to the influence of damage to the coating layer, peeling of the paint film occurred, but the occurrence of the above damage was small, and although the occurrence of corrosion under the paint film was clearly observed, it was slight.

×: Severe damage to the coating layer, significant peeling of the coating, and significant corrosion remaining under the coating.

■ Rust resistance for the outside surface To evaluate the rust resistance of the EOE outside surface, 20 cycles of a cycle test were conducted under the following conditions.

Salt water spray test (5 inches NaCfl 35'CX 1 hour) → Humidity tank storage (49°Q, RH 98 degrees or more x 1 hour)
→Leave indoors (22 hours) The rusting status of the rivet-processed area that underwent EOE processing was observed and evaluated.

In addition, the evaluation criteria were based on the following method.

◎・・・・・・No rust caused by damage such as cracks to the coating layer due to processing. (E.O.
Rust occurrence rate in the E-processed part is 0%) ○... Slight occurrence of rust due to damage to the coating is observed (Rust occurrence rate in the EOE-processed part is less than 10%)
*) △・・・・・・A considerable amount of rust is observed due to damage to the coating. (Rust occurrence rate in EOE processing part: 10-3
0chi not t4) ×...The occurrence of rust due to damage to the film is significant (rust occurrence rate in EOE processed parts is 30% or more) (Effects of the invention) Therefore, the steel plate of the present invention When used for electric resistance seam welded cans that are painted, or easy-open can lids that undergo severe processing, the following effects are achieved.

(,) Compared to the melting point of Ni metal (melting point: 1452°C), Ni-P alloy (17.4 wt% P; 1
175°C111 parts by weight; 880°C) coating layer with Ni,
One or two Ni-Co, Ni-Fe coating layers
Since it is applied as a surface layer of a base coating layer consisting of more than one layer, the contact resistance value during welding is reduced, thereby expanding the appropriate welding range.

(b) Since the Ni-P alloy coating layer is an amorphous layer, it prevents the occurrence of cracks even when subjected to severe processing such as riveting or winding.

In addition, since each coating layer has a different crystal form and hardness, even if a crack occurs, it stops propagating at the boundary between each layer, and its reach to the steel surface is significantly reduced.

(c) Ni in the Ni-P alloy single coating layer or the base coating layer.

Compared to a coating layer consisting of only one or more layers of Ni--Co or Ni--Fe, these superimposed coating layers have extremely reduced coating layer defects (pinholes).

Even if pinholes are generated, the Ni--P coating has an extremely large corrosion-preventing effect on the base coating layer, and is extremely effective in preventing pitting corrosion that occurs from defects formed in the base coating layer.

Therefore, the types of can contents are diversified.

(d) The coating layer in the present invention is smaller than the Sn plating layer.

Because of its high melting point, it is possible to apply a wider range of paint baking conditions compared to Sn-plated steel sheets, and it is possible to apply high-temperature painting treatments of 250°C or higher, which is a problem with Sn-plated steel sheets. The improvement in coating performance due to the mutual effect with the chromate coating layer applied to the outermost surface of the coating is extremely remarkable, although the reason is not clear, and the effect of improving paint adhesion and post-coating corrosion resistance is extremely significant.

Claims (1)

[Claims] On the surface of the steel plate, the amount of adhesion per one side composed of one or more layers of Ni, Ni-Co alloy, Ni-Fe alloy is 10
It has a base coating layer of 0 to 2000 mg/m^2, and the amount of Ni deposited on one side is 10 to 300 mg/m^2.
- Excellent corrosion resistance, weldability, and coating performance, characterized by having a P-based alloy coating layer and a chromate coating layer on the outermost layer with a coating amount of 3 to 50 mg/m^2 per side in terms of metal Cr content. Ni alloy multilayer plated steel sheet