JPS5843470B2 - Different types of multilayer plated steel sheets for can manufacturing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides coating corrosion resistance, can body bondability,
In particular, the present invention relates to a low-cost surface-treated steel sheet for making cans that has excellent seam weldability and two-piece can formability.

Surface-treated steel sheets for can manufacturing generally include electrolytic tin plated (hereinafter referred to as tinplate) and electrolytic chromic acid treated steel sheets (hereinafter referred to as TFS).
-CT) is known.

Among these, tinplate is the most common and most widely used surface-treated steel sheet for can manufacturing.

It is used as food cans for fish, soup, fruit, etc. by leaving the tin bare or after painting and taking advantage of the corrosion resistance of the pot.In addition, it can be used as so-called food cans for fish meat, soup, fruit, etc., as well as so-called beverage cans such as cola and other carbonated beverage cans, fruit juice cans, etc. It is also widely used for 181 cans, bale cans, etc.

As a can manufacturing method, tin is used not only for the so-called 3-piece can making process, but also for the production of 2-piece cans, which are particularly common in beverage cans, taking advantage of the solid lubricity of tin.

On the other hand, TFS-CT is mainly used for beverage cans, which are relatively less corrosive, and is also used for 1M cans, bale cans, etc., but the manufacturing method is only for 3-piece cans, and 2-piece cans. It is not used to make single cans.

This is because the non-metallic chromium layer (hereinafter referred to as oxide chromium layer) consisting mainly of metallic chromium and chromium hydrated oxide of TFS-CT is hard and brittle, making it difficult to process 2-piece cans. This is because the corrosion resistance after can processing is greatly reduced.

Even in the case of three-piece cans, the so-called adhesion method is the main method for joining the can body, and therefore, when seam welding is performed, it is necessary to remove the chromium layer on the surface, which is not common.

As mentioned above, the usual uses and manufacturing methods of conventional tinplate and TFS-CT take advantage of their respective advantages, and tinplate is mainly used for applications that require stable storage over a long period of time. It is manufactured into 3-piece cans and 2-piece cans, excluding cans made by the adhesive method.

On the other hand, TFS-CT is mainly used for short-term storage.
It is already well known that the can manufacturing method is mainly used to manufacture three-piece cans by adhesion.

However, with the recent rise in the price of tin, in order to reduce can manufacturing costs and conserve resources, tin plating has become thinner, and in order to compensate for the deterioration in corrosion resistance that comes with thinner tin plating, paint has been used instead of tin plating. The use of TFS-CT in applications where tinplate has traditionally been used is also increasing.

On the other hand, the production ratio of 2-piece cans has increased as a can manufacturing method.
Due to social demands such as PB regulations, 3-piece cans are also undergoing a change from the conventional method of joining can bodies using .

First of all, tin plating is thinly plated with tin, and currently, in practical terms, the amount of tin deposited on one side is 2.8? /m'', and this level of tin adhesion is said to be the lower limit at which the solid lubricity of tin can be fully demonstrated in 2-piece can molding.
Whether it is a one-piece can or a two-piece can, in order to improve corrosion resistance, three-piece cans are painted before can manufacturing, and two-piece cans are painted after can manufacturing. Most of them are.

Next is the conversion of tinplate to TFS-CT, but of course, as is well known, TFS-CT requires that the entire surface be painted before it is used, and the application is for highly corrosive materials such as fruit juice. It is not preferable to use it when the content is such that the elution of iron ions or iron ions is extremely difficult.

Furthermore, there are many problems in converting tinplate to TFS-CT, such as making it impossible to produce two-piece cans, the consumption of which has been increasing in recent years.

Therefore, in order to reduce can manufacturing costs, we aim to create a low-cost surface for can manufacturing that has bare corrosion resistance, painted corrosion resistance, can body formability, and particularly seam weldability and two-piece can formability that are equal to or better than conventional tinplate. The development of treated steel sheets has been requested from various quarters, and as a result of conducting research in response to these requests, the present inventors have succeeded in developing a completely new surface-treated steel sheet for can manufacturing that satisfies all of these quality requirements. be.

In other words, after first applying nickel plating to the front and back sides of the steel plate,
By layering tin plating only on the surface of one nickel plating layer and further providing chromium treatment layers on both sides, the aim is to provide a completely new dissimilar multilayer plated steel sheet with dissimilar plating layers on the front and back sides. By exploiting the difference in performance between the front and back sides, the range of uses will expand, and the effects can be expected from dogs.

The skin structure of the new surface-treated steel sheet of the present invention is schematically illustrated in FIG. 1.

Reference numeral 1 indicates a cold-rolled steel plate serving as a plating material, and 2 indicates a nickel plating layer.The plating method is not particularly limited, and electroplating, chemical plating, etc. may be used.

Reference numeral 3 denotes a tin plating layer, and the plating method for this layer is not particularly limited either, and either electroplating or chemical plating may be used, but electroplating is usually used most often.

The most distinctive feature of the present invention is that this tin plating layer 3 is plated on only one side, and this will be explained in detail later.

In FIG. 1, the tin plating layer 3 is shown on the top surface of the steel plate for convenience of explanation, but the tin plating layer 3 may be provided on either the top or bottom surface of the steel plate, that is, the front or back surface.

4 is a chromium-treated layer obtained by dipping or electrolytic chromic acid treatment.

No. 5 has an oil film layer formed (the oil film is formed from commonly used cottonseed oil, dibutyl separate, dibutyl separate, etc.) and uses the electrostatic oil coating method, which is usually used as a post-treatment for electric tinplates. be exposed.

Next, the reasons for the limitations of the present invention will be explained.

First, when nickel-plating a steel plate whose surface has been surface-cleaned using the usual method, the thickness of the nickel-plated layer is 10 mm per side.
mff/m2 or more is required.

This is because if the nickel plating thickness is less than 10 m5'/l-, defects in the upper tin plating or coating cannot be compensated for, leading to deterioration in corrosion resistance.

The upper limit of the double layer is 5000 mff per side.
/m2 is limited to 5000 mff/m2 per side.
If it is more than that, it will not only be disadvantageous in terms of cost, but also lead to deterioration of seam weldability when sea welding is adopted as the can body joining method.
Although it is limited to the range of mff/m2, when electroplating is adopted as the nickel plating method, it is also within the scope of the present invention to perform differential thickness plating on the front and back of the steel plate as nickel plating.

In other words, when using the Ni-plated single layer side on the outside of the can and the Sn/NiZ layer-plated side on the inside of the can, due to the corrosion resistance of the outside of the can, etc.
The amount of nickel coated on the single layer side of the plating is preferably 100 mV/m2 or more, especially when forming a drawn can (hereinafter referred to as DI can), 300 ms'/m2 or more.

On the other hand, it is sufficient that the amount of nickel coated on the Sn/Ni two-layer plating layer side is 10 mff/m2 or more and 1000 mft/m2 or less.

The same applies when the Ni-plated single layer side is used for the inner surface of the can and the Sn/NiZ layer-plated side is used for the outer surface of the can.In this way, in the new surface-treated steel sheet of the present invention, the amount of nickel plating coated depends on the can manufacturing method, The front and back sides of the steel plate can be plated with different thicknesses to best suit the required characteristics.

Next, when placing the tin plating layer on the nickel layer, the reason why the tin plating layer was limited to 50 to 11000 mft/m2 per side was that the amount of tin plating was 50711 f/711. Below 50mg/m2, tin hardly contributes to corrosion resistance, and most of the tin is alloyed with nickel or iron during the next reflow process or paint baking process during can manufacturing, worsening the surface color.
More than that is required, and 11000mf? /m2 or more, it is not only disadvantageous in terms of cost, but also the adhesion of the paint after painting deteriorates, and an excessive tin-iron alloy layer is formed during seam welding. The amount of tin plating is 50 m because the paint adhesion of the repair coating will deteriorate.
? /m2 to 11000 mV/m2.

Note that when using Sn/NiZ layer plating on the outer surface of the can and using nada for adhesion, the amount of tin required to satisfy the adhesion performance is preferably 1000 mV/m2 or more.

Next, the reason why tin plating is limited to only one side of the steel plate, which is the most distinctive feature of the present invention, is not only to reduce the amount of tin, but also to meet the required performance depending on the type of can. Advantages obtained by layering a tin layer that cannot be obtained with a single layer of nickel, specifically, the excellent drawability and corrosion resistance that tin itself has, and the paintability obtained as a result of the two layers of tin and nickel. and has good corrosion resistance after painting.

Next, the reason why the chromium treatment layer coating on both sides was limited to 3mf/m2 to 50 mft/m2 per side in terms of metal chromium is that below 3mfl/m2, there is almost no sealing effect for pinholes in the plating layer, and it is also used for can manufacturing. When using paint after painting, the paint adhesion is poor, so 3 m? /m2 or more, and since seam weldability and solder performance deteriorate at 50 ms'/m2 or more, it was set to 50 mV/m2 or less.

The range is preferably 5 to 20 mV/m2.

Here, the features of the dissimilar multilayer plated steel sheet for can manufacturing according to the present invention will be specifically explained while presenting an example of its use.

Table 1 shows specific examples to which the new surface-treated steel sheet of the present invention is applied.

Usage Examples 1 and 2 When the new surface-treated steel sheet of the present invention is used for applications that require bare corrosion resistance or painted corrosion resistance on the inside of the can, and workability when the DI forming method is adopted as the can body forming method, Types of cans include 3-piece cans and 2-piece cans.

When applying the dissimilar multilayer plated steel sheet for can manufacturing of the present invention,
If the can is manufactured with the Ni-Sn two-layer plating surface corresponding to the inner surface of the can, the following advantages can be obtained.

That is, in the present invention, the corrosion resistance of the surface obtained by adding a chromium treatment layer to the Ni-Sn two-layer plating was compared to the conventional tinplate #25 (single-sided Sn Adhesion amount 2.
8S'/m2), =#=100 (one side Sn adhesion amount 11f
? Table 2 shows the results of comparison with those of /m2).

The corrosion resistance of the two-layer plated surface of the present invention is 2.8f of tin attached to one side.
It has corrosion resistance equivalent to or higher than conventional #100 tinplate at approximately f/m2, and has a tin content of 1000 mWIn- on one side.
It can be seen that the following also has performance better than #25 tinplate, and is effective in improving corrosion resistance and reducing the tin content and area weight.

Next, when using it for inner-coated cans, this is also N.
The purpose can be achieved by using this surface as the inner surface by taking advantage of the iSn two-layer plating.

Conventionally, tinplate and TFS-CT have been used for cans with internal coatings, but depending on the type of can contents, tinplates with tin adhesion of 2.81/m2 or less per side and TFS-CT It is not recommended to use it for highly corrosive contents such as fruit juice, or for cases that need to be stored for a long time such as general food cans such as fish cans.Therefore, tinplate generally has a tin coating of 2.5 mm per side. As mentioned above, those of 8 S'/m2 or more are used for internally coated cans, and TFS-CT is relatively less corrosive and is used when it is consumed in a short period of time.

On the other hand, in the present invention, by applying the Ni-Sn two-layer plated surface to the inner surface of the can after painting, not only can the amount of tin adhesion be greatly reduced, but also the paint adhesion, which was a drawback of conventional tinplate, can be improved. can also be greatly improved.

In the present invention, when a Ni-Sn two-layer plating surface is used on the inner surface of an inner-coated can, the corrosion resistance inside the can is supplemented by the paint, so the plating coverage of nickel and tin is 1000 m9/m2, 2700 mV/m2, respectively. m2 or less is sufficient, and increasing the amount of nickel or tin plating beyond this will not only be disadvantageous in terms of cost, but also cause deterioration in coating performance such as paint adhesion, and there will be no advantage.

The coating amount of the chromium treatment layer should be 3 mft/m2 or more, but from the viewpoint of corrosion resistance inside the can, it is preferably 10if/m2.
The above is good, and from the point of view of seam weldability, 50 rILf
/m2 or less.

In addition, in these usage examples 1 and 2, the outer surface is plated with a single Ni layer, but the amount of Ni single layer plating is sufficient to provide corrosion resistance after can manufacturing, and preferably 100 mf? /m2 or more, but if the DI molding method is used as the can manufacturing method, 300 mV/m2 or more is preferable.

In addition, from the aspect of seam weldability, 5000771? /m2 or less.

Also, the amount of chromium treated layer is the same as that on the inner surface of the can.

Usage Examples 3 and 4 Usage Examples 3 and 4 are cases in which the outer surface of the can is plated with two layers of tin and nickel, and the inner surface of the can is plated with a single layer of nickel. The corrosivity of tin is relatively weak, and the outer surface of the can requires corrosion resistance or the luster of tin.For example, aerosol cans are considered, and the can manufacturing method is seam welding and soldering as the can body joining method. It is a 3-piece can that does this.

The amount of plating on the outer and inner surfaces of the can and the presence or absence of can manufacturing coating can be freely selected within the range of each coating amount limitation of the present invention, depending on the contents to be filled, the storage of the can, and the environment in which the can is used.

Usage example 3 is a 3-piece can, usage example 4 is a 2-piece can (a so-called squeeze can), and the inner surface of each can is limited to those that contain the mildly corrosive substances mentioned above, such as oil cans. The nickel single layer surface of the present invention can also be used in place of thinly plated tin plate (for example -#25ET) or TFS-CT.

However, the amount of nickel plating deposited is preferably 500 mg/m2 or more in order to ensure corrosion resistance on the inside of the can.

On the other hand, in response to the requirement for corrosion resistance on the outer surface of the can, the Ni-8nZ of the present invention
There are good reasons for using a layered surface.

FIG. 2 shows the results of a salt spray test conducted by the inventors to evaluate the corrosion resistance of the bare surface of a two-piece can after processing.

From the figure, N i −S n 2 of the new surface-treated steel sheet of the present invention
The corrosion resistance of the layer plated surface is superior to the conventional #50 tin plate #1
It has performance equivalent to or better than 00 tinplate.

The corrosion resistance was evaluated by the area where red rust occurred.

In the example of the present invention, Ni plating amount is 300 mW/m2, Sn
Plating amount 5500 mV/m2 Chromium treatment layer amount 15mf
/m2 (metallic chromium equivalent).

Use example 4 is a case where it is used in a two-piece can, and another reason for applying the Ni-Sn two-layer plating surface of the present invention to the outer can surface is that it takes advantage of the press lubricity of tin. It will be done.

The usual method for making two-piece cans involves forming a cup by drawing with a press, and then ironing the cup in two to three stages to stretch the side wall of the cup.

During this ironing process, the outer wall of the can is particularly strongly squeezed by the die.

Therefore, chrome plating such as TFS-CT is hard and has poor lubrication performance, so it cannot withstand ironing, and the plating layer has fine particles and racks, which deteriorates the corrosion resistance after can manufacturing.Also, the die is made of chrome, which is a hard metal. Therefore, it is subject to severe wear and cannot be used in practical use.

However, metals with a low melting point (melting point of tin: 232°C), such as tin, are highly malleable, so the heat generated during ironing provides a solid lubricant effect, and the corrosion resistance after can manufacturing does not deteriorate much. Also, it is suitable for two-piece molding because there is little die wear during continuous processing.

However, in the case of tinplate, the tin plating layer on the outer surface of the can is stretched and becomes thinner after the can is made, and the corrosion resistance after the can is deteriorated due to the inevitable increase in processing flaws in the plating layer. will use a thicker one.

Therefore, if the surface of the 5n-Ni two-layer plating layer of the new surface-treated steel sheet of the present invention is used on the outer surface of the can, the tin plating layer will have solid lubricity when forming the 2-piece can. By applying a nickel plating layer on the base, it is possible to obtain the advantage of killing two birds with one stone by preventing deterioration of corrosion resistance after processing.

As mentioned above, it can be seen from FIG. 2 that the Ni-Sn two-layer plated surface of the present invention has excellent corrosion resistance after processing.

As described above, the dissimilar multilayer plated steel sheet for can making of the present invention is described in Example 1 of Use.
As shown in 4-4, by using the right material in the right place depending on the purpose of the can, conventional tinplate and TFS-
This is an attractive new product as a completely new can-making material that can be used to take advantage of CT's individual strengths.

Next, the present invention will be explained in more detail with reference to Examples.

Example A cold-rolled steel plate was degreased and pickled in the usual manner, and electrolytic nickel plating was applied to both sides of the steel plate under the conditions shown in (1).
) Electrolytic tin plating is performed on only one side of the steel plate under the conditions shown in (3) and (4), followed by electrolytic chromic acid treatment on both sides of the steel plate under the conditions shown in (3) and (4), and an oil film of dioctyl sebacate is formed using a commonly known method. did.

As a comparison with the example of the present invention, a single-sided tin coating amount of 2800
mV/m2 and 5500 mV/m2, chromate coating amount 10 mV/m2 (metallic chromium equivalent) tinplate (hereinafter referred to as #25 tinplate and #50 tinplate) metal chromium amount per side 100 mft/m2, chromium oxide amount 12 m
ft/m2 (metallic chromium equivalent) TFS-CT was used.

Examples of the present invention, comparative examples, and conventional examples were subjected to various tests as shown below under the conditions described above, and their performances were evaluated.

(A) Salt water spray test A 3% NaCl solution was sprayed onto the sample surface for 44 hours, and the area of rust on the sample surface was examined.

(6) Tin elution test The sample was immersed in commercially available orange juice and sealed at 37°0.
After retention for 6 months, the amount of tin in the orange juice was measured.

(4) and (B) test results are shown in Table 3.

In this way, the examples of the present invention are superior to the conventional #50 tinplate.

(C: 1UCC (Undercut Corrosion) Test Apply 45mg/d♂ of epoxy phenol paint to the Ni-Sn 2 layer coated side, bake at 205℃ for XIO minutes, and add Kl for 10 minutes at 80℃ After baking and applying a knife scratch on the painted surface, immerse it in a corrosive solution (a mixture of 1,5% citric acid and 1,5 euchloride, etc.) and heat it at 50°C.
The three-pronged method, in which the scratched area was held for three days and the tape was peeled off to determine the corrosion state around the scratch, is a general method for evaluating the post-coating corrosion resistance of can-making materials.

0 Paint adhesion test A painted board painted under the same conditions as C) was immersed in a 3% NaCl solution as is (primary adhesion) at 125°C.
After retorting for 90 minutes (secondary adhesion) and after UCC test (adhesion after UCC), evaluation was made by making gongs with a knife at 2 mm intervals and peeling off the tape.

■ Seam welding Using a seam welding machine, stack the same type of plates 0.8 m apart.
Pressure force 50kg/CrIL2 or secondary side welding current 4, 5
The seam weldability was tested under KA conditions, the strength of the seam weld was evaluated by an impact test, and the appearance of the seam weld was visually evaluated.

The evaluation results of the above (O-■) are shown in Table 4.

From Table 4, the examples of the present invention have corrosion resistance after painting (UCC test)
The paint adhesion is equal to or better than #25 tinplate, and the seam weldability is also equal to #25 tinplate.

In Comparative Examples 1 to 4, the amount of nickel plating, the amount of tin plating, and the amount of chromium coating are outside the limited range of the present invention, but Comparative Examples 1 and 2 were tested by UCC test, and Comparative Example 3 was tested by seam weldability. Also, Comparative Example 4 was inferior in both UCC properties and paint adhesion.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view showing the coating structure of a dissimilar multi-layer plated steel sheet for can manufacturing according to the present invention, and Figure 2 is a comparison diagram of the corrosion resistance of the surface formed into a 2-piece can, evaluated by a salt spray test. be. 1... Cold rolled steel plate, 2... Nickel plating layer, 3...
-Tin plating layer, 4...Chromium treatment layer, 5...Oil film layer.

Claims (1)

[Claims] 1 A nickel plating layer with a thickness of 10 to 5000 m1/m2 per side is provided on the lower layer of both sides, an electrolytic tin plating layer of 50 to 11000 m1/m2 is provided on the nickel layer on only one side, and an amount of chromium is further applied on both sides of the steel plate. A dissimilar multi-layer plated steel sheet for can manufacturing, on which a chromium treatment layer of 3 to 50?7Lff/77+2 is formed in terms of metallic chromium per side.