JP4626485B2 - Surface-treated metal plate and manufacturing method thereof, resin-coated metal plate, metal can and can lid - Google Patents

Description

  The present invention is a metal plate that is mainly processed into a container such as a can, and in particular, a surface-treated metal plate excellent in adhesion to a resin such as a plastic film (hereinafter referred to as resin adhesion), and a method for producing the same, and The present invention relates to a resin-coated metal plate in which an organic resin is coated on the surface-treated metal plate, a metal can using the same, and a can lid.

  Various metal cans such as beverage cans, food cans, pail cans and 18 liter cans use metal plates such as electrolytic chromic acid treated steel plates called tin-plated steel plates or tin-free steel plates. Among these, tin-free steel plates are manufactured by electrolytic treatment of steel plates in a bath containing hexavalent chromium, and are characterized by excellent resin adhesion to paints and the like.

  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 to tin-free steel plates that do 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. Further, Patent Document 3 proposes a surface-treated metal material having an inorganic surface-treated layer containing Zr, O, and F as main components and hardly containing phosphate ions. Furthermore, Patent Document 4 proposes a method of surface-treating an aluminum material with a hydrophilic surface treatment agent containing polyacrylic acid and a zirconium compound.

On the other hand, various types of metal cans have been manufactured by processing metal plates such as tin-free steel plates and then processing them into cans. Instead of this, a method of processing a laminated metal plate (resin-coated metal plate) obtained by laminating a resin such as a plastic film into a can body is frequently used. This laminated metal plate requires that the resin and the metal plate are in close contact with each other. In particular, a laminated metal plate used as a beverage can or a food can may undergo a retort sterilization process after filling the contents. For this reason, strong resin adhesion that does not cause the resin to peel even in a high-temperature and humid environment is required.
JP 2004-285380 A Japanese Patent Laid-Open No. 2001-220685 JP 2005-97712 A JP-A-6-322552

  However, in the laminated steel plate using the container steel plate subjected to the electrolytic treatment in the tungstic acid solution described in Patent Document 1 and the container surface-treated steel plate in which the phosphate layer is formed on the surface described in Patent Document 2. In either case, the resin adhesion in the retort sterilization process is insufficient. Further, in the surface-treated metal material in which the inorganic surface treatment layer mainly composed of Zr, O, and F is formed on the surface described in Patent Document 3, the resin adhesion before canning is good, but the can The resin adhesion after processing is insufficient. Furthermore, when the method of surface treatment with a hydrophilic surface treatment agent containing polyacrylic acid and a zirconium compound described in Patent Document 4 is applied to a steel sheet, the adhesion between the base steel sheet and the treated film is poor. Thus, according to these conventional techniques, a substitute material for a tin-free steel plate cannot be obtained.

  The present invention provides a surface-treated metal plate that does not use chromium, has excellent resin adhesion, and can be used as a substitute for a tin-free steel plate, and a method for producing the same, and a resin-coated metal plate obtained by coating the surface-treated metal plate with an organic resin, An object is to provide a metal can and a can lid using the same.

  As a result of intensive research on a surface-treated metal plate excellent in resin adhesion without using chromium, the present inventors formed a film containing Zr and O on the surface, and further formed an organic film on the film It was found that extremely excellent resin adhesion can be obtained.

The present invention has been made based on such knowledge, and has a film containing Zr and O on at least one surface of a metal plate, and is formed by applying an organic acid on the film and then drying it. Provided is a surface-treated metal plate having an organic film.

In the surface-treated metal plate of the present invention, the Zr content of the coating containing Zr and O is preferably ³ to 200 mg / m ² .

The organic acids, hydroxy acids are preferable, citric acid, tartaric acid, glycolic acid, lactic acid, glyceric acid, more preferably of at least one acid selected from mandelic acid.

  The present invention also provides a resin-coated metal plate in which an organic resin is coated on the organic film of the surface-treated metal plate of the present invention, a metal can and a can lid using the same.

  The surface-treated metal plate of the present invention is, for example, formed by coating a metal plate with an organic acid after cathodic electrolysis treatment of the metal plate in an aqueous solution containing potassium fluoride zirconate, and drying to form an organic coating. It can be manufactured by the method of forming.

  According to the present invention, it is possible to produce a surface-treated metal plate that is excellent in resin adhesion without using chromium. The surface-treated metal plate of the present invention has no problem as an alternative to the conventional tin-free steel plate, and is coated with an organic resin to form a resin-coated metal plate. Can be processed without happening.

1) Surface-treated metal plate In the surface-treated metal plate of the present invention, a film containing Zr and O is formed on at least one surface of the metal plate, and an organic film is further formed on this film.

  As the metal plate, a general steel plate for cans, an aluminum plate, an aluminum alloy plate, or the like can be used.

  The film containing Zr and O formed on the surface of the metal plate is firmly bonded to the base metal plate, imparting corrosion resistance to the metal plate, and providing resin adhesion through a synergistic effect with the organic film formed on the metal plate. Improve. As a method for forming a film containing Zr and O, a method of immersing a metal plate in an aqueous zirconate solution, a method of electrolytically treating the metal plate in the same solution, or the like is suitable. As the zirconium salt, zirconium sulfate, zirconium acetate, zirconium nitrate, ammonium zirconium carbonate, potassium zirconium carbonate, potassium fluoride zirconate, ammonium fluoride zirconate, or the like can be used. In particular, the method of cathodic electrolysis of a metal plate in an aqueous potassium zirconate fluoride solution is preferable because a uniform film can be formed efficiently.

Zr amount of coating containing Zr and O are insufficient effect of improving adhesion between the resin and less than 3 mg / m ^2, not be expected further improvement in adhesion exceeds 200 mg / m ^2, cost Since it becomes high, it is preferable that it is 3-200 mg / m < ² >. The measurement of the Zr amount of the film can be performed by surface analysis using fluorescent X-rays. The amount of O is not particularly defined, but its presence can be confirmed by surface analysis using XPS.

  The organic film formed on the film containing Zr and O also contributes to resin adhesion with a plastic film or the like to be coated thereafter. The organic substance constituting the organic film is preferably a non-volatile substance that is solid at room temperature among alcohols, phenols, ethers, aldehydes, ketones, carboxylic acids, amines, and the like, and is made of such an organic substance. It is preferable to form an organic film. Of these, organic acids are preferred, and hydroxy acid is particularly preferred. Hydroxy acid is a general term for organic compounds having a carboxyl group and an alcoholic hydroxyl group in one molecule. In the present invention, hydroxy acid is selected from citric acid, tartaric acid, glycolic acid, lactic acid, glyceric acid, mandelic acid, and the like. At least one acid can be used. As a method for forming this organic film, a method in which the above organic substance is dissolved in water or an organic solvent, applied as a solution on a metal plate, and then dried is preferable. As a coating method, various known coating methods can be used. In order to shorten the drying time, a step of heating the metal plate may be provided as necessary. In addition, after forming a film | membrane by drying, it is preferable to remove the excess organic substance which remain | survived on the metal by passing through a water washing process. In this case, it is not necessary to perform particularly strong water washing, and it is sufficient to immerse in a water tank or water spray. After washing with water, it can be dried again and put to practical use.

If the adhesion amount of the organic film is less than 0.1 mg / m ² , the effect of improving the resin adhesion is insufficient, and if it exceeds 50 mg / m ² , cohesive failure occurs in the organic film, resulting in a decrease in resin adhesion. Since there exists a possibility, it is preferable that it is 0.1-50 mg / m < ² >. The amount of the organic film deposited can be measured by dissolving the film with water or an appropriate organic solvent and analyzing the composition of the gas generated by combustion by gas chromatography.

2) Resin-coated metal plate (laminated metal plate)
The organic film of the surface-treated metal plate of the present invention can be coated with an organic resin to form a resin-coated metal plate. As described above, since the surface-treated metal plate of the present invention is excellent in resin adhesion, the resin-coated metal plate has excellent corrosion resistance and workability.

  There is no limitation in particular as organic resin coat | covered on the surface treatment metal plate of this invention, Various thermoplastic resins and thermosetting resins can be mentioned. For example, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer, olefin resin film such as ionomer, or polyester film such as polybutylene terephthalate, or nylon 6 It may be a non-stretched or biaxially stretched thermoplastic resin film such as a polyamide film such as nylon 6,6, nylon 11, or nylon 12, a polyvinyl chloride film, or a polyvinylidene chloride film. When using an adhesive during lamination, urethane adhesive, epoxy adhesive, acid-modified olefin resin adhesive, copolyamide adhesive, copolyester adhesive (thickness: 0.1 to 5.0 μm), etc. Is preferably used. Furthermore, a thermosetting paint may be applied to the surface-treated metal plate side or film side in a thickness range of 0.05 to 2 μm, and this may be used as an adhesive.

  Furthermore, modified epoxy paint such as phenol epoxy, 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, Synthetic rubber paint such as styrene-butadiene copolymer, etc. It may be a combination.

  In the present invention, the thickness of the organic resin coating layer is desirably 3 to 50 μm, particularly 5 to 40 μm. When the thickness is below the above range, the corrosion resistance becomes insufficient, and when the thickness is above the above range, problems are likely to occur in terms of workability.

  In the present invention, the formation of the organic resin coating layer on the surface-treated metal plate can be performed 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. it can. 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 metal plate and thermally bonding it. That is, after melt-kneading the organic resin with an extruder, it is extruded from the T-die into a thin film, and the extruded molten resin film is passed through a pair of laminating rolls with a surface-treated metal plate to be pressed and integrated under cooling, Then quench rapidly. When extrusion coating a multilayer organic resin coating layer, an extruder for the surface layer resin and an extruder for the lower layer resin are used, and the resin flow from each extruder is merged in a multi-layer die, and thereafter Extrusion coating may be performed as in the case of the layer resin. Moreover, an organic resin coating layer can be formed on both surfaces of the surface-treated metal plate by passing a surface-treated metal plate vertically between a pair of laminate rolls and supplying a molten resin web to both sides thereof.

3) Metal can and can lid As long as the metal can of the present invention is formed from the above-mentioned resin-coated metal plate, any can-making method may be used. The metal 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, bent and stretched by drawing and redrawing (stretching), and stretched and drawn by drawing and redrawing so that the surface of the surface-treated metal plate coated with the organic resin faces the inner surface of the can. -It is manufactured by attaching to a conventionally known means such as ironing or drawing / ironing.

  The can lid of the present invention may be formed by any conventionally known lid-making method as long as it is formed from the above-described resin-coated metal plate. 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 various modifications can be made within the scope of the claims.

As a metal plate,
A: Low carbon cold-rolled steel sheet with a thickness of 0.20mm and tempering grade T-4
B: Ultra low carbon cold-rolled steel sheet with a thickness of 0.20mm and tempering grade T-2
C: Using a JIS5021H18 aluminum plate with a plate thickness of 0.28 mm, after alkaline degreasing and pickling, in the treatment liquid of the composition shown in Table 1, it is subjected to cathodic electrolysis under the same conditions as shown in Table 1, washed with water, The film containing Zr and O was dried to form both surfaces of the metal plate. In the cathode electrolysis treatment, iridium oxide-coated titanium was used for the anode. Subsequently, an organic treatment liquid having the composition shown in Table 1 was applied onto a metal plate using a roll coater, dried for 20 seconds in an electric furnace at 80 ° C., washed with water to form an organic film, and a surface-treated metal. Plates No. 1 to 11 were produced. Here, in the surface-treated metal plate No. 5, coatings containing Zr and O are formed on both surfaces of the metal plate not by electrolytic treatment but by immersion treatment.

  For comparison, electrolytic treatment was performed using the metal plate A under the conditions shown in Table 2, and a portion of the metal plate was then immersed in an immersion treatment liquid having the composition shown in Table 2 for 1 second to obtain a surface-treated metal. Plate No. 12-14 were produced. No treatment for forming an organic film on any metal plate is performed. Here, in the surface-treated metal plates No. 12 and No. 13, a film containing Zr and O and a W-containing film are formed on both surfaces of the metal plate by cathodic electrolysis, respectively, and in No. 14, after the anodic electrolysis The Mg-containing film is formed on both surfaces of the metal plate by immersing in an aqueous magnesium phosphate solution.

  Surface treatment metal plate No. 1-12 Zr adhesion amount, No. 13 W adhesion amount, No. 14 Mg adhesion amount, respectively, by comparison with a calibration plate obtained by wet analysis of the adhesion amount in advance This was performed by fluorescent X-ray analysis. The presence of O was confirmed by XPS surface analysis. Moreover, the adhesion amount of the organic film of the surface-treated metal plates No. 1 to 12 was measured by dissolving the film in water or ethanol and analyzing the composition of the gas generated by combustion by gas chromatography. Tables 1 and 2 show the amount of Zr, W, Mg, and organic film.

  Laminated metal plates (resin coating) were laminated on both surfaces of these surface-treated metal plates No. 1 to 14 with an isophthalic acid copolymerized polyethylene terephthalate film (organic resin coating layer) having a thickness of 25 μm and a copolymerization ratio of 12 mol%. Metal plates No. 1 to 14 were prepared. Lamination was performed by sandwiching a metal plate heated to 245 ° C. and a film between a pair of rubber rolls, fusing the film to the metal plate, and cooling with water within 1 second after passing through the rubber roll. At this time, the feed speed of the metal plate was 40 m / min, and the nip length of the rubber roll was 17 mm. Here, the nip length is the length in the conveyance direction of the portion where the rubber roll and the metal plate are in contact. And about the produced laminated metal plate No. 1-14, the following resin adhesiveness evaluation was performed.

i) Resin adhesion evaluation (1)
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 off a part 3 of the metal plate 1 while leaving the film 2 as shown in FIG. As shown in b), this 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 30 minutes. Then, the peeling length 5 shown in FIG. 1 (c) was measured, and the resin adhesion was evaluated as follows.
○: Peel length is less than 20mm △: Peel length is 20mm or more and less than 70mm ×: Peel length is 70mm or more
ii) Resin adhesion evaluation (2)
The can is processed under the conditions shown in Table 3, and after making a cut with a cutter knife at a position 10 mm from the upper end of the outer surface of the can body, retort treatment is performed for 15 min at 130 ° C while immersed in tap water. It was. And the film peeling length from a cut end was measured, resin adhesiveness was evaluated as follows, and if it was (circle), it was considered that resin adhesiveness was favorable.
○: Film peel length is less than 1 mm Δ: Film peel length is 1 mm or more and less than 10 mm ×: Film peel length is 10 mm or more Table 4 shows the evaluation results of resin adhesion. In laminated metal plates Nos. 1 to 11 which are examples of the present invention, all show good resin adhesion. On the other hand, in the laminated metal plate No. 12, which is a comparative example, the resin adhesion evaluation (1) is good, but the resin adhesion evaluation (2) is inferior because it does not have an organic film. Further, the laminated metal plates No. 13 and No. 14 which are comparative examples do not have a film containing Zr and O, and therefore the resin adhesion evaluations (1) and (2) are inferior.

  Using the laminated metal plates No.1, 3-6, and 14 produced in Example 1, the cans were processed under the conditions shown in Table 3, and the opening end of the can body was necked in and flanged to make a metal seamless can No. 1-6 were produced. In addition, using the same laminated metal plate, a 209-diameter SOT lid was prepared, and the inner and outer surfaces of the score processed part were repaired with an epoxy phenol-based paint.

  The produced metal cans Nos. 1 to 6 and the lids were visually inspected for abnormalities such as peeling of the film after the can making and perforation. After filling a metal can with a coffee drink at 50 ° C, double-wrap the lid, perform a retort treatment at 125 ° C for 25 min, leave it at 37 ° C for 6 months, and then open the can. Corrosion and film abnormalities were examined visually.

  The results are shown in Table 5. For metal cans Nos. 1 to 5 using the laminated metal plate according to the present invention, the metal can and the lid were examined after making the can and filling the contents, but in any case, no abnormality of the film could be confirmed.

  On the other hand, in metal can No. 6 using a laminated metal plate not according to the present invention, film abnormality after can making, film abnormality (peeling) and corrosion after filling contents were confirmed.

It is a figure explaining a 180 degree peel test.

Explanation of symbols

1 Metal plate
2 film
3 Parts cut out of a metal plate
4 weights
5 Peel length

Claims (8)

A surface-treated metal sheet comprising a film containing Zr and O on at least one surface of a metal sheet, and an organic film formed by applying an organic acid on the film and then drying . ^2. The surface-treated metal sheet according to claim 1, wherein the Zr content of the coating containing Zr and O is 3 to 200 mg / m ² . The surface-treated metal plate according to claim 1 or 2 , wherein the organic acid is a hydroxy acid.   The surface-treated metal sheet according to claim 3, wherein the hydroxy acid is composed of at least one acid selected from citric acid, tartaric acid, glycolic acid, lactic acid, glyceric acid, and mandelic acid. A resin-coated metal plate, wherein an organic resin is coated on the organic film of the surface-treated metal plate according to any one of claims 1 to 4 . A metal can comprising the resin-coated metal plate according to claim 5 . A can lid comprising the resin-coated metal plate according to claim 5 .   A surface-treated metal characterized in that a metal plate is subjected to cathodic electrolysis in an aqueous solution containing potassium fluoride zirconate to form a film containing Zr and O, and then an organic acid is applied and dried to form an organic film. A manufacturing method of a board.

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