JP3218923B2 - Surface-treated steel sheet for painted or film-laminated two-piece can with excellent work adhesion and work corrosion resistance, and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated steel sheet which is a material steel sheet for two-piece cans which is subjected to severe processing after coating or film laminating, and particularly to a coating or film excellent in adhesion and corrosion resistance after processing. Laminate 2
The present invention relates to a surface-treated steel sheet for a piece can and a method for producing the same.

[0002]

2. Description of the Related Art In a conventional can-making process, a tin plate, an electrolytic chromate-treated steel plate (hereinafter, referred to as TFS), a metal plate such as aluminum is coated once or a plurality of times, and then a can-making process is performed. In some cases, painting may be performed after can processing. In the manufacturing process of a can lid and a cap, it is common to apply a coating to a metal plate and then process it.

In recent years, a technique for laminating an organic resin film on a metal plate has been developed and put into practical use. JP-A-57-182428, JP-B-61-3676.
Japanese Patent Application Laid-Open Publication No. H11-133, etc. discloses a method in which a metal plate is heated to a temperature equal to or higher than the melting point of a film and bonded by heat fusion.

[0004] There are various methods for processing after coating or film lamination. Particularly high processing is performed by drawing or squeezing, squeezing, pulling, bending or the like on a metal plate alone or in combination. There is a two-piece can manufacturing method in which a can bottom and a can body are integrally formed by repeatedly performing the process as needed.

On the other hand, in recent years, can manufacturers have been reducing the thickness of can bodies from the viewpoint of material saving.
In the case of piece cans, measures are taken to increase the degree of processing during can making. In the production of can lids and caps, metal plates after painting or film lamination are subjected to processing such as drawing, bending, overhanging, and screw processing.

By the way, severe processing performed after painting or film lamination has a great influence on the form of the plating film on the base surface-treated steel sheet. For example, in the case of TFS, when the coating film or the film is dissolved and removed from the material after the draw bead processing and the plating film is observed, a number of cracks are generated in the metal chromium layer and the hydrated chromium oxide, and the new surface of the metal chromium and iron is formed. It has been found to appear. This is because the outermost resin film has a large ductility, so it shows a healthy appearance even when subjected to fairly severe processing, but the electrolytic chromate film is extremely thin, and the hydrated chromium oxide layer has low ductility and is deformed due to processing. Cracks because it cannot follow
It is considered that the new surface of iron and chromium metal is exposed.

[0007] The adhesion between the resin film and the base surface-treated steel sheet after processing depends on the adhesion state after processing of the interface between the resin film and the electrolytic chromate coating film, and the contact state between the newly formed surface of iron and metallic chromium and the resin film. Therefore, the adhesiveness after processing (hereinafter referred to as processing adhesiveness) is caused by the fact that cracks occur in the electrolytic chromate-treated film to reduce a sound adhesive interface and that the adhesive force between the new surface and the resin film interface is weak. )
And the corrosion resistance (hereinafter referred to as processing corrosion resistance) is deteriorated.

As described above, if the degree of processing is increased in order to reduce the wall thickness for the purpose of saving the material, performance such as processing adhesion and processing corrosion resistance is greatly deteriorated. Further, the film adhesion method by the above-mentioned heat fusion also has a large deterioration in processing adhesion and processing corrosion resistance, and is hardly practical.

As a technique for solving such a problem, a method of laminating an organic resin film coated with an adhesive in advance on a metal plate is disclosed in Japanese Patent Publication No. 4-74176.
It is disclosed in Japanese Patent Publication No. 5-71035, Japanese Patent Application Laid-Open No. 2-70430, and the like.

According to the methods disclosed in these publications, the working adhesion and the working corrosion resistance are improved, but it is necessary to evaporate the solvent of the adhesive by heating it, which not only complicates the process but also reduces the amount of solvent discharged. This causes problems such as treatment of wastewater and an increase in energy consumption, which is not preferable from the viewpoint of environmental conservation.

Further, in the case where particularly severe processing is performed in the manufacturing process, further processing adhesion and processing corrosion resistance are required, and when exposed to a high-temperature steam environment during retort processing, the degree of performance deterioration is further increased. Therefore, even with these techniques, the degree of improvement in processing adhesion and processing corrosion resistance is still insufficient, and there is a problem that it cannot be applied to some contents.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has excellent processing adhesion and processing corrosion resistance even when severe processing is performed after painting or film lamination. It is an object of the present invention to provide a surface-treated steel sheet for painted or film-laminated two-piece cans and a method for producing the same, which can be applied to all contents, including contents that require the following.

[0013]

In order to solve the above-mentioned problems, the present inventors have developed a TFS which is a surface-treated steel sheet having relatively good adhesion to an organic resin layer such as a painted or laminated film. Using as a base, the bonding mechanism at the bonding interface between the resin film and TFS was examined in detail. In addition, a detailed investigation was conducted on the bonding interface when subjected to severe processing after bonding with paint or a laminate film, and processing adhesion and processing corrosion resistance in an aqueous environment of the inner surface after filling the contents or in a high-temperature steam environment during retort processing. The mechanism by which the metal deteriorates was investigated in detail.

As a result, in order to suppress the deterioration of the work adhesion and the work corrosion resistance, the hydrogen bonding force which is dominant in the adhesion between the hydrated chromium oxide layer present on the uppermost layer of TFS and the paint or laminate film is required. It has been found that it is important to increase the content, and it is effective to provide an organic substance having a specific polar group. In addition, for the part where a new metal surface appears at the bonding interface due to deformation due to processing, re-adhesion occurs after processing, and furthermore, it is possible to suppress degradation of characteristics by collecting eluted metal ions. They have found that it is possible to use the above-described method of providing an organic substance having a polar group in this mechanism.

The present invention has nothing to do with the conventional method of applying an adhesive to a film at the time of laminating, and thus, by applying a specific organic substance to the hydrated chromium oxide layer of TFS, it is possible to paint or coat the film. The inventors have found that the work adhesion and work corrosion resistance after severe processing of the steel sheet after lamination are remarkably improved and completed.

That is, according to the present invention, first, the lower layer is formed on at least one surface of the base steel sheet in an amount of 30 to 300 per side.
mg / m ² of metallic chromium layer, the upper layer has an electrolytic chromate conversion coating consisting of hydrated chromium oxide layer of 5 to 30 mg / m ² of metal per side terms of chromium, further carboxyl groups in the molecule thereon A coating having excellent processing adhesion and processing corrosion resistance, comprising an organic layer containing at least one kind of organic resin having a molecular weight of 1000 or more and having an average adhesion amount of 1 to 1000 mg / m ² as a solid concentration. Provided is a surface-treated steel sheet for a film-laminated two-piece can.

Second, the organic material layer is characterized in that the total weight of carboxyl groups based on the total weight of organic materials is 1% or more, and the surface for painted or film-laminated two-piece cans excellent in process adhesion and process corrosion resistance. Provide treated steel sheet.

Thirdly, in any one of the above inventions, the organic material layer contains at least one of polyacrylic acid and a derivative thereof, wherein the coating or film laminate is excellent in processing adhesion and processing corrosion resistance. 2
Provide surface treated steel sheet for piece cans.

Fourth, by subjecting the steel sheet to electrolytic chromate treatment directly or after chromium plating, a metal chromium layer of 30 to 300 mg / m ² per side on at least one side of the steel sheet and a metal chromium layer After forming two layers of a hydrated chromium oxide layer with a conversion of 5 to 30 mg / m ² , after washing with water or washing with water and drying, 0.3 g of an organic substance containing at least one kind of polymer containing a carboxyl group in the molecule. The present invention provides a method for producing a coated or film-laminated two-piece surface-treated steel sheet having excellent work adhesion and work corrosion resistance, which comprises applying an aqueous solution containing a solution having a concentration of at least / l and then drying.

According to the present invention having such a configuration,
Suppresses the deterioration of processing adhesion and corrosion resistance due to the increase in workability due to the thinning of can bodies, which has been promoted from the viewpoint of resource saving, and can be applied to contents that require retort treatment, etc., which is a high-temperature steam environment. Painting or film lamination 2
The surface-treated steel sheet for a piece can can be provided without increasing the cost.

Hereinafter, the present invention will be described in detail. The conventional mechanism of adhesion between a TFS having a hydrated chromium oxide layer on the surface and a resin film such as a film or paint is as follows.
It is considered that the dominant one is caused by a hydrogen bond acting between the hydroxyl group of the hydrated chromium oxide layer and the polar group of the resin film. Therefore, there is no other way to increase the adhesion between the hydrated chromium oxide layer and the resin film except to change the resin film itself or the quality of the hydrated chromium oxide layer. However, even if the quality of the hydrated chromium oxide layer is changed, there is no other way but to reduce the mixing ratio of other anions contained in the electrolytic chromate treatment or to change the anion species. Since it does not change, there is naturally a limit in improving the adhesion.

On the other hand, the present invention provides a hydrated chromium oxide upper layer having a carboxyl group in the molecule having a molecular weight of 1,000.
Since the above organic resin is contained, the bonding mechanism itself is significantly different from the conventional one. That is, since an organic resin having a carboxyl group and a molecular weight of 1000 or more forms a hydrogen bond stronger than the hydrogen bond between the hydrated chromium oxide and the resin film, the use of such an organic resin significantly improves the adhesion. You do it.

The present invention can provide not only the effect of improving the primary adhesion to the resin film described above but also the following effects. When processing after bonding the resin film to TFS, the resin film can be deformed according to the processing, but the metal chromium layer and the hydrated chromium oxide layer are cracked and become island-like. New chromium and iron surfaces. In the conventional TFS, the portion that bears the adhesion after processing is dominated by the adhesion between the hydrated chromium oxide layer and the resin film remaining after processing, and the adhesion between the newly formed surface of iron and metallic chromium and the resin film. Because the force is extremely low, the overall adhesion is significantly reduced.
However, the surface-treated steel sheet according to the present invention has an organic resin having a carboxyl group between the newly formed surface of iron and metal chromium that appears after processing and the resin film, and has an adhesive force, and thus has excellent adhesion after processing. That is, if the adhesion between the organic resin having a carboxyl group and the resin film is superior to the adhesion between the organic resin having a carboxyl group and the hydrated chromium oxide layer, even after processing, the newly formed surface of iron and metal chromium and the resin There will be an organic resin with a carboxyl group between the films, and in the opposite case,
When the hydrated chromium oxide cracks during processing and breaks into islands, the organic resin having a carboxyl group bridges between islands or slides and attaches to the resin film side. Will go. In any case, an organic resin having a carboxyl group exists between the newly formed surface of iron and metallic chromium and the resin film.

It is considered that such a polymer is not linear but is three-dimensional, and it is advantageous to leave some room for elongation against processing deformation. Or it is considered disadvantageous if it is short. Under the processing environment, the new surface of iron and metallic chromium is oxidized as quickly as possible to produce hydroxyl groups,
The presence of the organic resin layer having a carboxyl group between the nascent surface and the resin film produces a strong adhesive force, and the adhesiveness is excellent even after processing.

Further, the carboxyl group can be esterified by causing a dehydration reaction with the metal hydroxide, and when the reaction occurs under the high temperature conditions at the time of bonding to the resin film and at the time of processing, the bonding which controls the bonding is performed. Is changed from a hydrogen bond to a covalent bond, so that the bonding force is dramatically increased.

Furthermore, the surface-treated steel sheet of the present invention has excellent adhesion in a high-temperature aqueous environment or a steam environment. In general, the adhesion deteriorates under the above-mentioned environment when water invades the interface between the resin film and the steel sheet,
Because of the polarity of the water, it is likely that the water replaces the hydrogen bonds that support the adhesion. However, in the present invention, the organic resin having a carboxyl group is a conventional T resin.
Since it has a stronger hydrogen bond than FS, it is hard to be replaced by water, and therefore has excellent adhesion even in a high-temperature aqueous environment or steam environment.

Moreover, the fact that the hydrogen bond is hardly replaced by water molecules has the effect of preventing expansion leakage,
Corrosion resistance after processing is also excellent. Furthermore, carboxyl groups have the ability to trap cations as used in ion exchange resins. Therefore, the carboxyl group collects the eluted iron ions. In a system in which a new surface of iron is exposed after processing, such a mechanism for trapping iron ions does not exist in the conventional TFS. Therefore, as compared with the conventional TFS, the surface-treated steel sheet of the present invention is significantly improved in the work corrosion resistance.

Hereinafter, the reasons for limiting the invention will be described.
In the present invention, at least one surface of the base steel sheet has a two-layer electrolytic chromate treatment film in which the lower layer is a metal chromium layer and the upper layer is a hydrated chromium oxide layer.

Here, the amount of deposited metal chromium in the lower layer is 30 to 300 mg / m ² per one side. The amount of adhesion is 30
If the amount is less than mg / m ² , there is a problem in corrosion resistance, and 300
If it exceeds mg / m ² , the processability is inferior.
In any case, there is no problem as long as the amount is used for a normal electrolytic chromate treated steel sheet.

The amount of hydrated chromium oxide in the upper layer is 5 to 30 mg / m ^{2 in} terms of metallic chromium per side. If the adhesion amount is less than 5 mg / m ² , the metal chromium layer is not uniformly covered with the hydrated chromium oxide, the exposed area of the metal layer becomes large, and the corrosion resistance, the aging deterioration resistance, and the processing adhesion are inferior. On the other hand, if it exceeds 30 mg / m ² , the hydrated chromium oxide layer is unfavorably caused because the hydrated chromium oxide layer is too thick, which causes deterioration in appearance and adhesion.

An organic layer containing at least one organic resin having a carboxyl group in the molecule and having a molecular weight of 1000 or more and having an average adhesion amount of 1 to 1000 mg / m ² as a solid content concentration is formed on the electrolytic chromate treatment film. It is formed. Here, in the organic layer containing a resin having a carboxyl group in the molecule, the total weight of the carboxyl groups with respect to the total organic substance weight is preferably 1% or more. This is because the carboxyl group can function effectively at this concentration or more, and can exert the effect of significantly improving the adhesion.

In the present invention, examples of the organic resin having a carboxyl group in the molecule include polyacrylic acid, itaconic acid, derivatives thereof, and copolymers containing them. More than one species is contained. Among them, polyacrylic acid and its derivatives can be suitably used, and at least one of them can be contained.

The organic layer may contain other organic substances such as polyethylene glycol and polyvinyl alcohol in addition to the organic resin having a carboxyl group in the molecule.

It is necessary that the molecular weight of the organic resin having a carboxyl group in the molecule is at a high molecular level of 1,000 or more. The reason why the molecular weight is specified to be 1000 or more is that if the molecular weight is low, it cannot be stretched at the time of processing as described above, and the processing adhesion cannot be sufficiently improved. Although there is no particular upper limit on the molecular weight of the organic resin,
It is preferably not more than 10,000.

The average adhesion amount of the organic layer is 1 to 1000 mg.
/ M ² . 1m to effectively improve adhesion
g / m ² is the minimum required and 1000 mg / m ²
This is because, even if the ratio exceeds 1, the effect of improving the adhesion is saturated, and the thickness of the organic material layer is increased, so that cohesive failure easily occurs in the polymer, which adversely affects the adhesion. Further, in order to make the average amount adhered to 100 mg / m ² or more, it is necessary to use appropriate equipment capable of uniformly adhering organic substances so as not to impair the surface appearance, and it takes time to dry. It is uneconomical because it is difficult to produce in-line on a production line. Therefore, it is preferable that the average amount of adhesion be less than 100 mg / m ² .

In the present invention, the steel sheet is subjected to electrolytic chromate treatment directly or after chromium plating, so that at least one side of the steel sheet has a thickness of 30 to 300 m per side.
g / m ² chromium metal layer and ^two layers of 5-30 mg / m ² hydrated chromium oxide layer in terms of metal chromium per side are formed on the upper layer, and after water washing or water washing and drying,
An aqueous solution containing an organic substance containing at least one polymer having a carboxyl group in the molecule at a concentration of 0.3 g / l or more is applied, and then dried to produce a surface-treated steel sheet having the above-described structure.

Here, the electrolytic chromate treatment method is a one-liquid method in which chromium metal and hydrated chromium oxide are simultaneously precipitated.
And a two-liquid method in which a hydrated chromium oxide is deposited after the formation of the metal chromium layer.

When forming the organic material layer, the aqueous solution to be applied on the electrolytic chromate-treated film contains 0.3 g of the organic material.
/ L or more. If the concentration is lower than this, the effective amount does not adhere to the steel sheet surface, and it is difficult to sufficiently increase the adhesion.

The base steel sheet is not particularly limited, and any steel sheet usually used for this type of surface-treated steel sheet can be used. For example, a low carbon Al-killed steel sheet can be used.

[0040]

Next, specific examples of the present invention will be described. [Test materials] (1) Surface-treated steel sheet All examples and comparative examples are low carbon Al-killed continuous cast steel, a T4CA material having a thickness of 0.20 mm as an original steel strip.
It was manufactured using a vertical TFS line.

Next, an electrolytic chromate treatment shown in Table 1 was performed, and then an aqueous solution of an organic substance or an aqueous solution in which an organic emulsion was dispersed was applied under the same conditions as shown in Table 1, and dried to form an organic substance layer. The amount of the organic layer deposited was controlled by adjusting the pressing pressure of the squeezing roll or setting the coating roll. Table 2 shows the substances used for the organic layer.

(2) Coating The surface-treated steel sheets described in Examples and Comparative Examples were 200 × 3
A cut plate having a thickness of 00 mm was coated with an epoxy resin paint on both sides under the following conditions and baked.

Epoxy resin paint adhesion amount: 60 mg / dm ² (after drying) Baking temperature: 210 ° C. Baking time: 10 minutes (3) Film lamination The surface-treated steel sheet described in Examples and Comparative Examples was 200 × 3.
A cut sheet of 00 mm was formed, and a commercially available polyester film was laminated on both sides under the following conditions.

Film: Biaxially oriented polyester film (copolymer of polyethylene glycol and terephthalic acid / isophthalic acid) Film thickness: 25 μm Crystal melting temperature of film: 229 ° C. Steel sheet temperature immediately before lamination: 235 ° C. Laminating speed: 2 m / Sec Cooling after lamination: water cooling (rapid cooling) [Evaluation] (1) Drawing workability A painted or laminated surface-treated steel sheet was punched into a disk having a diameter of 158 mm, and a cylindrical cup was drawn at a drawing ratio of 2.92. Thereafter, the peeling state of the film or coating on the inner surface of the cup was observed with a loupe. At that time, five points were set to a good state without delamination, and the evaluation was made in five stages so that the degree of delamination increased as the number of points decreased to four points, three points, two points, and one point.

Further, a retort treatment was carried out in a 1.5% NaCl + 1.5% citric acid aqueous solution for 90 minutes, washed with water and dried, and the peel strength of the inner surface of the cup was similarly evaluated in five steps based on the same standard.

(2) Bending work Painted or laminated surface-treated steel sheet is 30 × 300 mm
Using a tool with a tip R of 0.25 mm, a draw bead test is performed at a holding pressure of 1000 kgf, and a 15% compression process is performed by a rolling mill, and a loupe is formed on the opposite side of the draw bead tool contact surface. Was observed. At this time, the degree of peeling was evaluated in five steps as in the evaluation of the drawability.

A retort treatment was performed in 1.5% NaCl + 1.5% citric acid aqueous solution for 90 minutes. Similarly, the opposite side of the contact surface of the draw bead tool was observed with a loupe, and evaluated on a 5-point scale based on the same standard.

(3) Repack test A laminated surface steel plate is punched into a disk having a diameter of 110 mm.
First, a cylindrical cup is drawn with a draw ratio of 1.51,
Next, redrawing was performed at a drawing ratio of 1.20, and a cylindrical cup (total drawing ratio of 1.81) was prepared. The state of peeling of the film on the inner surface of the cup was observed with a loupe, and evaluated on a 5-point scale based on the same criteria as above.

Also, Coca-Cola (trade name) is contained in the cup.
Were repacked and subjected to a storage test at 38 ° C. for 3 months.
After this storage test, the peeling state of the film and the metal plate on the inner surface of the cup was observed with a loupe, and evaluated on a 5-point scale based on the same criteria as above. At the same time, iron ions eluted in Coca-Cola were determined by atomic absorption method.

The results of these evaluations are also shown in Table 1.
As shown in Table 1, the surface-treated steel sheets of Examples that are within the scope of the present invention have not only excellent primary adhesion after painting or film lamination, but also adhesion after processing, and further after retorting. It was confirmed that the adhesiveness was excellent. Further, the amount of iron eluted when the contents were stored for a long time was extremely small, and it was confirmed that the processing corrosion resistance was remarkably improved.

On the other hand, the comparative examples out of the range of the present invention were particularly inferior in processing adhesion after retort treatment and corrosion resistance during storage of contents. As described above, it was confirmed that by using the surface-treated steel sheet according to the present invention, excellent processing adhesion and processing corrosion resistance can be obtained regardless of the electrolytic chromating method. It should be noted that the present invention is not limited to the above-described embodiment, and can be carried out in other various modes without departing from the gist of the present invention.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

As described above, according to the present invention,
It is excellent in processing adhesion and processing corrosion resistance even when subjected to severe processing after painting or film lamination, and can respond to increase in processing degree due to thinning of can body, requiring retort treatment Provided are a surface-treated steel sheet for a painted or film-laminated two-piece can and a method for producing the same, which can be applied to all kinds of contents such as the following contents. As described above, according to the present invention, since excellent processing adhesion and processing corrosion resistance can be obtained without going through complicated steps, its economic value is extremely high.

Continuation of the front page (51) Int.Cl. ⁷ identification code FI C23C 22/24 C23C 22/24 28/00 28/00 C C25D 11/38 301 C25D 11/38 301A 303 303 (56) References JP 57-19398 (JP, A) JP-A-2-70430 (JP, A) JP 4-74176 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05D 1/00 -7/26 B32B 15/08 104 C23C 22/24 C23C 28/00 C25D 11/38 301 C25D 11/38 303

Claims (4)

(57) [Claims] 1. A metal chromium layer having a lower layer of 30 to 300 mg / m ² per one side and a hydrated chromium oxide layer of 5 to 30 mg / m ^{2 in} terms of metal chromium per one side on at least one surface of a base steel sheet. Comprising an electrolytic chromate-treated film comprising at least one organic resin having a carboxyl group in the molecule and having a molecular weight of 1000 or more, and having an average adhesion amount of 1 mg / m ² or more as a solid concentration of 1
200 mg / m and having an organic substance layer is less than ^2, processing adhesion and processing corrosion resistance superior full I Lum laminated two-piece can for surface treated steel sheet. 2. The process according to claim 1, wherein the organic material layer has a total weight of carboxyl groups of 1% or more based on the total weight of the organic material.
Off I Lum laminated two-piece can for surface treated steel sheet was. Wherein the organic material layer, polyacrylic acid and off I Lum laminate having excellent processability adhesion and processing corrosion resistance according to claim 1 or claim 2, characterized in that it comprises at least one of its derivatives Surface treated steel plate for two-piece cans. 4. The steel sheet is subjected to electrolytic chromate treatment directly or after chromium plating, whereby a metal chromium layer of 30 to 300 mg / m ² per side on at least one side of the steel sheet and a metal chromium layer per side thereof are converted to metal chromium per side. 5-
Forming two layers of 30 mg / m ² hydrated chromium oxide layer,
After washing with water or washing and drying , at least a polymer having a carboxyl group in the molecule and having a molecular weight of 1,000 or more is obtained.
By applying an aqueous solution containing one kind of organic substance at a concentration of 0.3 g / l or more and then drying , an average amount of adhesion is obtained.
Solids concentration as 1 mg / ^{m 2} or more 100 mg / ^{m 2} un
And forming an organic material layer is fully, processability adhesion and method for producing superior La Mi sulfonates film two-piece can for surface-treated steel sheet to the processing corrosion resistance.