JP2014177677A - Manufacturing method of surface-treated steel plate and surface-treated steel plate, resin-coated steel plate, and can and can top - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a surface-treated steel plate that has superior resin adhesion and corrosion resistance and may replace a tin-free steel plate by not using chromium, and using only conventional plating facilities without requiring thermal diffusion processing facilities after plating, the surface-treated steel plate obtained by the manufacturing method, a resin-coated steel plate formed by coating the surface-treated steel plate with organic resin, and a can and a can top that use the same.SOLUTION: A manufacturing method of a surface-treated steel plate includes forming a coating containing Ti and O through a cathode electrolytic treatment in a solution containing Ti after forming an Ni layer on at least one surface of a steel plate through electrodeposition so that an Ni amount is 50-1,000 mg/mand then forming an Fe layer on the Ni layer through electrodeposition so that the mass ratio of an Fe amount to the Ni amount is 0.5-5.0.

Description

  The present invention mainly relates to a method of manufacturing a surface-treated steel sheet excellent in adhesion (hereinafter referred to as resin adhesion) and corrosion resistance to a steel sheet, particularly a plastic film or the like, which is used by processing into a container such as a can. The present invention relates to a surface-treated steel sheet obtained by the method, a resin-coated steel sheet obtained by coating the surface-treated steel sheet with an organic resin, a can using the same, and a can lid.

  Various metal cans such as beverage cans, food cans, pail cans and 18 liter cans use steel plates such as electrochromated steel plates called tin-plated steel plates or tin-free steel plates. In particular, tin-free steel plates do not require the use of expensive tin, are produced by electrolytic treatment of steel plates in a bath containing hexavalent chromium, and have excellent resin adhesion to paints and the like. There is a special feature.

  In recent years, with the increasing awareness of the environment, the use of hexavalent chromium has been restricted worldwide, and alternative materials are also required for tin-free steel sheets that use a hexavalent chromium bath for production. As an alternative material for a tin-free steel plate that does not use chromium, for example, Patent Document 1 discloses a steel plate for containers that has been subjected to electrolytic treatment in a tungstic acid solution. Patent Document 2 discloses a surface-treated steel sheet for containers having a phosphate layer formed on the surface thereof. Further, Patent Document 3 has a phenol structure containing one or more of tannic acid or acetic acid and one or more of Ti or Zr or a compound thereof on a surface treatment layer containing one or more of Sn and Ni. A steel plate for containers to which a resin film is applied has been proposed. Patent Document 4 proposes a surface-treated metal material that does not contain phosphate ions and has an inorganic surface treatment layer and an organic surface treatment layer mainly composed of Zr, O, and F. Patent Document 5 proposes a surface-treated steel sheet having a film containing Ti and O on an Fe—Ni alloy layer.

  On the other hand, various metal cans have traditionally been manufactured by coating tin-free steel plates, etc., and then processing them into cans. A method of processing a laminated steel plate (resin-coated steel plate) in which a resin such as a plastic film is laminated into a can body is frequently used. In this laminated steel plate, it is necessary that the resin and the steel plate are strongly adhered, and particularly in the laminated steel plate used as a beverage can or food can, a retort sterilization process may be performed after filling the contents, Strong resin adhesion is required so that the resin does not peel off even in a high temperature and humid environment. Further, the steel sheet used for the laminated steel sheet needs to have corrosion resistance that does not cause a hole due to being attacked by the contents of the can even when the resin film is partially lost due to scratches or the like.

JP 2004-285380 A JP 2001-22085A Japanese Patent Laid-Open No. 2002-355921 JP 2006-009047 A JP 2009-052102 A

  However, a steel plate for containers subjected to electrolytic treatment in a tungstic acid solution described in Patent Document 1, a laminated steel plate using a surface-treated steel sheet for containers having a phosphate layer formed on the surface thereof described in Patent Document 2, And the steel sheet for containers to which the resin film having a phenol structure described in Patent Document 3 is used, the resin adhesion in the retort atmosphere is insufficient. In the surface-treated metal material on which the inorganic surface treatment layer mainly composed of Zr, O, and F and the organic surface treatment layer described in Patent Document 4 are formed, the corrosion resistance of the resin defect portion is insufficient. In Patent Document 5, in order to produce an Fe—Ni alloy layer, Ni plating is performed on a steel sheet, and then heat diffusion treatment is performed, so that Ni and Fe are strongly compatible. In resin adhesion, a sufficiently good result may not always be obtained. Furthermore, a dedicated facility for performing the thermal diffusion treatment is necessary, and there is a problem that the equipment cost is high.

  The present invention does not use chromium, does not require post-plating heat diffusion treatment equipment, and uses only conventional plating equipment, so that it has excellent resin adhesion and corrosion resistance, and can be a substitute for tin-free steel sheets. An object of the present invention is to provide a method for producing a treated steel sheet, a surface-treated steel sheet obtained by the production method, a resin-coated steel sheet obtained by coating an organic resin on the surface-treated steel sheet, a can using the same, and a can lid.

  As a result of intensive research on a surface-treated steel sheet that can be used as a substitute for a tin-free steel sheet without using chromium, and having excellent resin adhesion and corrosion resistance, the present inventors have formed a Ni layer on the steel sheet and then on the Ni layer. It was found that extremely good resin adhesion and corrosion resistance can be achieved by forming a Fe layer on the Fe layer and further forming a film containing Ti and O on the Fe layer.

The present invention has been made on the basis of such knowledge, and at least one surface of a steel plate is subjected to electroplating so that the amount of Ni is 50 to 1000 mg / m ² to form a Ni layer. Further, after forming an Fe layer by performing electroplating so that the Fe amount is 0.5 to 5.0 in terms of mass ratio to the Ni amount, Ti and A are subjected to cathodic electrolysis in an aqueous solution containing Ti. The present invention provides a method for producing a surface-treated steel sheet, wherein a film containing O is formed.

Regarding the film containing Ti and O, the amount of Ti is preferably 5 to 200 mg / m ² .

  The present invention also provides a surface-treated steel sheet obtained by the above production method. Furthermore, a resin-coated steel sheet coated with an organic resin on the surface-treated steel sheet of the present invention, a can using the same, and a can lid are provided.

  According to the present invention, a surface-treated steel sheet having excellent resin adhesion and corrosion resistance can be produced by using only conventional plating equipment without using chromium. The surface-treated steel sheet of the present invention has no problem as an alternative to the conventional tin-free steel sheet, and even if it is coated with an organic resin to form a resin-coated steel sheet and processed into a can or can lid, the resin does not peel at all. Further, even in a resin deficient part due to scratches or the like, Fe has a corrosion resistance with very little elution of Fe from the base iron.

It is a figure explaining a 180 degree peel test.

1) Formation of Ni layer and Fe layer In the surface-treated steel sheet of the present invention, a general steel sheet for cans can be used as the steel sheet. First, an Ni layer is formed by performing electroplating on at least one surface of a steel plate so that the Ni amount is 50 to 1000 mg / m ^{2. On the} Ni layer, the Fe amount is 0 by mass ratio to the Ni amount. An Fe layer is formed by performing electroplating so as to be .5 to 5.0. In this manner, two electroplating layers composed of the Ni layer and the Fe layer are formed.

  In order to form a two-layer electroplating layer consisting of a Ni layer and a Fe layer from the steel plate side, a well-known plating bath containing Ni ions (for example, a watt bath or a sulfamic acid bath) is used for electroplating. An appropriate method is to form the Fe layer by forming the layer and then washing with water, followed by electroplating using a plating bath containing Fe ions (eg, ferrous sulfate aqueous solution). In order to suppress divalent Fe ions from being oxidized by air during plating, an antioxidant can be appropriately added to the bath.

Among these plating layers, Ni is imparted with corrosion resistance by being firmly bonded to and coated with the underlying steel plate. When the amount of Ni is less than 50 mg / m ² , when the organic resin coating layer on the steel sheet surface is cracked due to contact with a tool or impact applied to the can body when it is processed into a can, a defect occurs. The organic resin is peeled off and the iron base is corroded, which hinders the function of the can. On the other hand, if the Ni content exceeds 1000 mg / m ² , further improvement in corrosion resistance cannot be expected, resulting in an increase in cost. Therefore, the Ni amount is 50 to 1000 mg / m ² .

  Further, among the plated layers, Fe contributes to improvement in adhesion with an organic resin. Although the detailed mechanism is unknown, when forming the chemical conversion treatment layer containing Ti and O on the plating layer, Fe is incorporated into the chemical conversion treatment layer, and the surface of the chemical conversion treatment film containing Ti and O is finely formed. Thus, it is considered that the contact area with the organic resin is increased and the adhesion is improved. Such an effect of improving adhesion cannot be obtained from a layer (Ni—Fe alloy layer) in which the Ni plating layer and the steel sheet base Fe are thermally alloyed by thermal diffusion. Compared with Fe co-deposited with Ni by electroplating or Fe deposited by electroplating with Fe alone, Fe bound to Ni is formed by chemical conversion containing Ti and O described later. This is thought to be because it is difficult to be incorporated into the treatment layer. Accordingly, in the present invention, the heat diffusion treatment is not performed after the plating treatment, and the two electroplating layers composed of the Ni layer and the Fe layer are formed in a stable manner. Thereby, compared with the case of a Ni-Fe alloy layer, adhesiveness with organic resin improves.

  Regarding the amount of Fe, when the mass ratio with respect to the amount of Ni is less than 0.5, the incorporation of Fe into the chemical conversion treatment layer containing Ti and O is insufficient, and sufficient adhesion cannot be obtained. On the other hand, if the mass ratio to Ni exceeds 5.0, Fe is likely to elute from the defective portion of the organic resin coating layer, and sufficient corrosion resistance cannot be obtained. Therefore, the Fe amount is set to 0.5 to 5.0 in terms of mass ratio with respect to the Ni amount.

The Ni amount can be measured by surface analysis using fluorescent X-rays. Regarding the measurement of Fe amount, a cross-section thin film sample of the plating layer is prepared by FIB (Focused Ion Beam) method, elemental analysis is performed using a transmission electron microscope with an energy dispersive X-ray analyzer, and Ni The element ratio can be obtained and converted into a mass ratio for quantification.
2) Formation of coating containing Ti and O In the present invention, the coating containing Ti and O (oxygen) formed on the two electroplating layers composed of the Ni layer and the Fe layer improves the resin adhesion. It is indispensable. A film containing Ti and O has a stronger resin adhesion than other oxides (for example, an oxide film made of Zr and O), and is a very effective film for obtaining a resin adhesion comparable to a tin-free steel plate. It is.

  The coating containing Ti and O is formed by a method of cathodic electrolysis in an aqueous solution containing Ti from the viewpoint of controlling the amount of Ti. The amount of Ti can be easily controlled by appropriately selecting the current density and electrolysis time during cathodic electrolysis. Note that the amount of Ti in the film can be measured by surface analysis using fluorescent X-rays. The amount of O is not particularly specified, but its presence can be confirmed by surface analysis using XPS.

  As a method for forming a film containing Ti and O, a method of cathodic electrolysis in an aqueous solution containing fluorotitanate ions, or a water-free solution containing no fluorine such as titanium sulfate, titanium nitrate, titanium lactate, titanium oxalate, etc. A method of cathodic electrolysis in an aqueous solution in which a porous titanium material is dissolved is suitable. As the compound that gives fluorotitanate ions, fluorinated titanate, ammonium fluoride titanate, potassium fluoride titanate, and the like can be used. In particular, a method of cathodic electrolysis in an aqueous solution containing potassium fluorinated titanate is preferable because it can form a uniform film efficiently.

In the present invention, when the amount of Ti in the film is 5 mg / m ² or more, the surface coverage is sufficient, and the effect of improving the adhesion with the organic resin is sufficiently obtained. If the amount of Ti is 200 mg / m ² or less, the cost is not increased and sufficient adhesion can be improved. Therefore, the Ti amount is preferably 5 to 200 mg / m ² .

  When a film containing Ti and O is formed, an organic substance can be added to the bath. It is also possible to form an organic film on a film containing Ti and O. In this case, it is performed by immersing the steel sheet in an organic solution. As the organic substance, for example, a non-volatile substance that is solid at room temperature is preferable among alcohols, phenols, ethers, aldehydes, ketones, carboxylic acids, amines, and the like, and an organic film made of such an organic substance is formed. It is preferable. For example, organic acids, particularly hydroxy acids are suitable. Hydroxy acid is a general term for organic compounds having a carboxyl group and an alcoholic hydroxyl group in one molecule, and is at least one selected from citric acid, tartaric acid, glycolic acid, lactic acid, glyceric acid, mandelic acid, and the like. The acid can be used. After the treatment, the steel sheet can be washed with water and dried to form a film.

  The surface-treated steel sheet produced by the method of the present invention can be coated with an organic resin to form a resin-coated steel sheet (laminated steel sheet). As described above, since the surface-treated steel sheet produced by the method of the present invention is excellent in resin adhesion, this resin-coated steel sheet has excellent corrosion resistance and workability.

There is no limitation in particular as an organic resin coat | covered on the surface treatment steel plate of this invention, Various thermoplastic resins and a thermosetting resin can be mentioned. For example, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer, olefin resin film such as ionomer, polyester film such as polybutylene terephthalate, or nylon 6 It may be a non-stretched or biaxially stretched thermoplastic resin film such as a nylon film such as nylon 6,6, nylon 11 or nylon 12, a polyvinyl chloride film or a polyvinylidene chloride film. When an adhesive is used for lamination, urethane adhesive, epoxy adhesive, acid-modified olefin resin adhesive, copolyamide adhesive, copolyester adhesive, etc. (thickness: 0.1 to 5) 0.0 μm) is preferably used. Further, a thermosetting paint may be applied to the surface-treated steel sheet side or the film side in a thickness range of 0.05 to 2 μm, and this may be used as an adhesive.
Furthermore, modified epoxy paints such as phenol epoxy and amino-epoxy, vinyl chloride-vinyl acetate copolymer, saponified vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, epoxy-modified- Epoxyamino-modified, epoxyphenol-modified-vinyl paint or modified vinyl paint, acrylic paint, thermoplastic or thermosetting paint such as synthetic rubber paint such as styrene-butadiene copolymer, or a combination of two or more kinds It may be a combination.

In the present invention, the thickness of the organic resin coating layer is preferably in the range of 3 to 50 μm, particularly 5 to 40 μm. If the thickness is 3 μm or more, the corrosion resistance is sufficient, and if the thickness is 50 μm or less, the workability is also excellent.
In the present invention, the organic resin coating layer can be formed on the surface-treated steel sheet by any means, for example, by an extrusion coating method, a cast film thermal bonding method, a biaxially stretched film thermal bonding method, or the like. . In the case of the extrusion coating method, it can be produced by extrusion coating an organic resin in a molten state on a surface-treated steel plate and thermally bonding it. That is, after melt-kneading the organic resin with an extruder, it is extruded into a thin film from a T-die, and the extruded molten resin film is passed through a pair of laminate rolls together with a surface-treated steel sheet and pressed and integrated under cooling, Cool quickly. When extrusion coating a multi-layered organic resin coating layer, use multiple extruders for each layer, merge the resin flow from each extruder in a multi-layer die, and thereafter, as in the case of a single layer resin Extrusion coating may be performed. Moreover, an organic resin coating layer can be formed on both surfaces of the surface-treated steel sheet by passing the surface-treated steel sheet vertically between a pair of laminate rolls and supplying a molten resin web to both sides thereof.

  As long as the can of the present invention is formed from the above-mentioned resin-coated steel sheet, any can manufacturing method may be used. The can can be a three-piece can having a side seam, but is generally preferably a seamless can (two-piece can). This seamless can is drawn and redrawn, drawn and stretched by drawing and redrawing (stretching), and stretched and drawn by drawing and redrawing so that the coated surface of the organic resin on the surface-treated steel sheet is on the inner surface of the can. It is manufactured by subjecting it to a conventionally known means such as ironing or drawing / ironing.

  Moreover, the can lid of this invention may be based on the conventionally well-known arbitrary lid-making method, as long as it is formed from the resin-coated steel plate mentioned above. In general, the present invention can be applied to a stay-on-tab type easy open can lid and a full open type easy open can lid.

  The above description is merely an example of the embodiment of the present invention, and the present invention is not limited thereto.

  As a steel plate, a low carbon cold rolled steel plate having a thickness of 0.20 mm and a tempering degree T-4 is used, and after alkaline degreasing and pickling, in the treatment liquid having the bath composition of the treatment bath E shown in Table 1. Then, cathodic electrolysis was performed at the temperature and current density shown in Table 1, Ni layers were formed on both surfaces of the steel sheet, washed with water, and then in the treatment liquid having the bath composition of treatment bath F shown in Table 1. Cathodic electrolysis was performed at the current density and processing temperature shown in FIG. 1 to form Fe layers on both surfaces of the steel sheet. Subsequently, cathodic electrolysis is carried out at the temperature and current density shown in Table 1 in a treatment solution having the bath composition G or I shown in Table 1, and dried to form films containing Ti and O on both surfaces of the steel sheet. did.

  The surface-treated steel sheet shown in Table 3 was produced by the above method. By adjusting the cathode electrolysis time in each treatment bath, inventive examples (Nos. 1 to 9) and comparative examples (Nos. 10 to 19) deviating from the scope of the inventive examples were produced.

Moreover, the surface treatment steel plate (No. 20) shown in Table 3 was similarly produced in the following procedure as a comparative example that deviated from the scope of the present invention.
As a steel plate, a low carbon cold-rolled steel plate having a thickness of 0.20 mm and a tempering degree T-4 was used, and after alkaline degreasing and pickling, the same treatment was performed in the treatment liquid of treatment bath E shown in Table 1. Cathodic electrolysis was performed at the current density and processing temperature shown in FIG. 1, and Ni electroplating layers were formed on both surfaces of the steel sheet. Thereafter, the steel plate was annealed at 700 ° C. in a 10 vol% H ₂ + 90% vol N ₂ atmosphere to diffuse Ni and Fe of the steel plate to each other, thereby forming an Fe—Ni alloy layer on the steel plate. Subsequently, cathodic electrolysis is performed in the treatment liquid having the bath composition shown in Table 1 at the current density and treatment temperature shown in Table 1, and dried to form a coating containing Ti, Fe, and O on both surfaces of the steel sheet. (No. 20).

These surface-treated steel plates No. A laminated steel plate (resin-coated steel plate) was prepared by laminating an isophthalic acid-copolymerized polyethylene terephthalate film (organic resin coating layer) having a thickness of 25 μm and a copolymerization ratio of 12 mol% on both surfaces 1 to 20. Lamination was performed by sandwiching a surface-treated steel sheet heated to 210 ° C. and a film between a pair of rubber rolls, fusing the film to the steel sheet, and cooling with water within 1 sec after passing through the rubber roll. At this time, the feeding speed of the steel plate was 40 m / min, and the nip length of the rubber roll was 14 mm. Here, the nip length is the length in the transport direction of the portion where the rubber roll and the steel plate are in contact. And the produced laminated steel plate No.1. About 1-23, the following characteristic evaluation test was done.
Resin adhesion test:
Laminated steel plate No. For 1 to 20, the resin adhesion was evaluated by a 180 ° peel test in a retort atmosphere at a temperature of 130 ° C. and a relative humidity of 100%. The 180 ° peel test is a test piece (size: 30 mm × 100 mm) obtained by cutting a part 3 of the steel plate 1 while leaving the film 2 as shown in FIG. As shown, it is a film peeling test performed by attaching a weight 4 (100 g) to one end of the test piece, turning it 180 ° to the film 2 side, and allowing it to stand for 60 minutes. And the peeling length 5 shown to (c) of FIG. 1 was measured, resin adhesiveness was evaluated as follows, and if it was (double-circle) or (circle), it was considered that resin adhesiveness was favorable.
A: Peeling length is less than 15 mm B: Peeling length is 15 mm or more and less than 20 mm B: Peeling length is 20 mm or more and less than 50 mm X: Peeling length is 50 mm or more After continuous treatment Resin adhesion test:
In order to evaluate the stability of the film performance against the continuous electrolytic treatment, the electrolytic film was electrolyzed under the same conditions as the initial stage after the electrolytic treatment was performed for a total of 2 hours at the treatment liquid temperature and current density shown in Table 1. The resin adhesion was examined according to the above procedure, and if it was ◎ or ◯, it was determined to be good.
A: Peel length is less than 15 mm B: Peel length is 15 mm or more and less than 20 mm B: Peel length is 20 mm or more and less than 50 mm X: Peel length is 50 mm or more Corrosion resistance test:
Laminated steel plate No. Cuts reaching the steel plate substrate using a cutter were crossed on 1 to 20 resin-coated surfaces, and an immersion test was performed under the following test solution composition and conditions.
Test liquid composition: citric acid 1.5% by mass, salt 1.5% by mass
Test temperature: 38 ° C
Test period: 21 days Corrosion resistance of the cut part was evaluated as follows.
○: almost no film peeling and corrosion Δ: slight film peeling and corrosion ×: remarkable film peeling and corrosion Real can storage test:
Laminated steel plate No. 1 to 20, cans were made under the conditions shown in Table 2, and the opening end of the can body was necked in and flanged to create a seamless can No. 1-20 were produced. Moreover, using the same laminated steel plate, a 209-diameter SOT lid was prepared, and the inner and outer surfaces of the score processed portion were repaired with an epoxy phenol-based paint.

The produced steel can No. For 1 to 20 and the lid, after filling the steel can with a coffee drink at 50 ° C., the lid is double wrapped, retorted at 125 ° C. for 25 min, left at 55 ° C. for 3 months and then opened. The corrosion and film abnormality on the inner surface of the can were visually examined.
○: No film peeling or corrosion △: Slight film peeling or corrosion ×: Film peeling or corrosion is remarkable Resin adhesion test, resin adhesion test after continuous treatment, corrosion resistance test, actual can storage test Table 3 shows.

  No. which is an example of the present invention. 1 to 9 all show good test results. On the other hand, No. which is a comparative example. 10 to 19 are inferior in any or all of the results of the resin adhesion test, the resin adhesion test after continuous treatment, the corrosion resistance test, and the actual can storage test. No. For No. 20, the results of the resin adhesion test, the corrosion resistance test, and the actual can storage test were good, but the results of the resin adhesion test after continuous treatment were poor.

DESCRIPTION OF SYMBOLS 1 Steel plate 2 Film 3 Part cut out of steel plate 4 Weight 5 Peeling length

Claims (6)

A Ni layer is formed on at least one surface of the steel plate by electroplating so that the Ni amount is 50 to 1000 mg / m ^{2. On the} Ni layer, the Fe amount is 0.5 by mass ratio to the Ni amount. A surface treatment characterized in that after forming an Fe layer by electroplating to be ~ 5.0, a film containing Ti and O is formed by cathodic electrolysis in an aqueous solution containing Ti A method of manufacturing a steel sheet. The method for producing a surface-treated steel sheet according to claim ² , wherein the amount of Ti in the coating containing Ti and O is 5 to 200 mg / m2.   A surface-treated steel sheet obtained by the method for producing a surface-treated steel sheet according to claim 1 or 2.   A resin-coated steel sheet, wherein the surface-treated steel sheet according to claim 3 is coated with an organic resin.   A can comprising the resin-coated steel sheet according to claim 4.   A can lid comprising the resin-coated steel sheet according to claim 4.

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