JP7384151B2 - Steel plate for cans and its manufacturing method - Google Patents
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- 229910000831 Steel Inorganic materials 0.000 title claims description 91
- 239000010959 steel Substances 0.000 title claims description 91
- 238000004519 manufacturing process Methods 0.000 title claims description 39
- 239000011651 chromium Substances 0.000 claims description 105
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 100
- 229910052804 chromium Inorganic materials 0.000 claims description 100
- 239000007864 aqueous solution Substances 0.000 claims description 27
- 229910052751 metal Inorganic materials 0.000 claims description 27
- 239000002184 metal Substances 0.000 claims description 27
- 150000001875 compounds Chemical class 0.000 claims description 12
- 229910052731 fluorine Inorganic materials 0.000 claims description 12
- 239000011737 fluorine Substances 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 11
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 8
- -1 fluorine ions Chemical class 0.000 claims description 8
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 claims description 6
- 239000010410 layer Substances 0.000 description 67
- 230000007797 corrosion Effects 0.000 description 21
- 238000005260 corrosion Methods 0.000 description 21
- 239000011347 resin Substances 0.000 description 13
- 229920005989 resin Polymers 0.000 description 13
- 239000002585 base Substances 0.000 description 9
- 238000005868 electrolysis reaction Methods 0.000 description 9
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 8
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 229910000423 chromium oxide Inorganic materials 0.000 description 5
- 239000003513 alkali Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- QQVIHTHCMHWDBS-UHFFFAOYSA-N isophthalic acid Chemical compound OC(=O)C1=CC=CC(C(O)=O)=C1 QQVIHTHCMHWDBS-UHFFFAOYSA-N 0.000 description 4
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- QQVIHTHCMHWDBS-UHFFFAOYSA-L isophthalate(2-) Chemical compound [O-]C(=O)C1=CC=CC(C([O-])=O)=C1 QQVIHTHCMHWDBS-UHFFFAOYSA-L 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 229920000139 polyethylene terephthalate Polymers 0.000 description 2
- 239000005020 polyethylene terephthalate Substances 0.000 description 2
- KMUONIBRACKNSN-UHFFFAOYSA-N potassium dichromate Chemical compound [K+].[K+].[O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O KMUONIBRACKNSN-UHFFFAOYSA-N 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Inorganic materials [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- QLOKJRIVRGCVIM-UHFFFAOYSA-N 1-[(4-methylsulfanylphenyl)methyl]piperazine Chemical compound C1=CC(SC)=CC=C1CN1CCNCC1 QLOKJRIVRGCVIM-UHFFFAOYSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 238000004873 anchoring Methods 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 235000011132 calcium sulphate Nutrition 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical class [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 229910001430 chromium ion Inorganic materials 0.000 description 1
- 229940117975 chromium trioxide Drugs 0.000 description 1
- GAMDZJFZMJECOS-UHFFFAOYSA-N chromium(6+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Cr+6] GAMDZJFZMJECOS-UHFFFAOYSA-N 0.000 description 1
- VQWFNAGFNGABOH-UHFFFAOYSA-K chromium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Cr+3] VQWFNAGFNGABOH-UHFFFAOYSA-K 0.000 description 1
- QFSKIUZTIHBWFR-UHFFFAOYSA-N chromium;hydrate Chemical compound O.[Cr] QFSKIUZTIHBWFR-UHFFFAOYSA-N 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 239000012611 container material Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-M hydrogensulfate Chemical compound OS([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-M 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000010409 ironing Methods 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- QPJSUIGXIBEQAC-UHFFFAOYSA-N n-(2,4-dichloro-5-propan-2-yloxyphenyl)acetamide Chemical compound CC(C)OC1=CC(NC(C)=O)=C(Cl)C=C1Cl QPJSUIGXIBEQAC-UHFFFAOYSA-N 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- NROKBHXJSPEDAR-UHFFFAOYSA-M potassium fluoride Chemical compound [F-].[K+] NROKBHXJSPEDAR-UHFFFAOYSA-M 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Landscapes
- Electroplating Methods And Accessories (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
- Electroplating And Plating Baths Therefor (AREA)
Description
本発明は、缶用鋼板およびその製造方法に関する。 The present invention relates to a steel plate for cans and a method for manufacturing the same.
特許文献１～２には、「鋼板の表面に、前記鋼板側から順に、金属クロム層およびクロム水和酸化物層」を有し、更に、金属クロム層が「粒状突起」を有する缶用鋼板が開示されている。 Patent Documents 1 and 2 describe a steel sheet for cans that has a "metallic chromium layer and a chromium hydrated oxide layer on the surface of the steel sheet in order from the steel sheet side," and the metal chromium layer further has "granular protrusions." is disclosed.
近年、缶用鋼板に要求される特性のレベルが高まっている。とりわけ、製缶加工後の耐食性がより良好な缶用鋼板が求められている。
そこで、本発明は、耐食性に優れる缶用鋼板およびその製造方法を提供することを目的とする。
In recent years, the level of properties required of steel sheets for cans has increased. In particular, there is a need for steel sheets for cans that have better corrosion resistance after can manufacturing.
Therefore, an object of the present invention is to provide a steel plate for cans having excellent corrosion resistance and a method for manufacturing the same.
本発明者らが鋭意検討した結果、下記構成を採用することにより、上記目的が達成されることを見出し、本発明を完成させた。 As a result of intensive studies, the present inventors have found that the above object can be achieved by employing the following configuration, and have completed the present invention.
すなわち、本発明は、以下の［１］～［７］を提供する。
［１］鋼板の表面に、上記鋼板側から順に、金属クロム層およびクロム水和酸化物層を有し、上記金属クロム層の付着量が、５０～２００ｍｇ／ｍ２であり、上記クロム水和酸化物層のクロム換算の付着量が、１５ｍｇ／ｍ２以上であり、上記金属クロム層は、平板状の基部と、上記基部上に設けられた粒状突起と、を含み、上記粒状突起の最大粒径が、１００ｎｍ以下であり、上記粒状突起の個数密度が、１０個／μｍ２未満である、缶用鋼板。
［２］上記クロム水和酸化物層のクロム換算の付着量が、３０ｍｇ／ｍ２超である、上記［１］に記載の缶用鋼板。
［３］上記クロム水和酸化物層のクロム換算の付着量が、３２ｍｇ／ｍ２以上である、上記［１］または［２］に記載の缶用鋼板。
［４］上記［１］～［３］のいずれかに記載の缶用鋼板を製造する方法であって、鋼板に対して、六価クロム化合物およびフッ素含有化合物を含有する水溶液を用いて、陰極電解処理Ｃ１、陽極電解処理Ａ１および陰極電解処理Ｃ２を、この順に施し、上記陽極電解処理Ａ１の電流密度が、１０．０Ａ／ｄｍ２以上であり、上記陽極電解処理Ａ１の電気量密度が、５．０Ｃ／ｄｍ２以上である、缶用鋼板の製造方法。
［５］上記水溶液におけるＣｒ量が、０．５０ｍｏｌ／Ｌ以上であり、上記水溶液におけるＦ量が、０．１０ｍｏｌ／Ｌ超である、上記［４］に記載の缶用鋼板の製造方法。
［６］上記陰極電解処理Ｃ２の電流密度が、２０．０Ａ／ｄｍ２以上であり、上記陰極電解処理Ｃ２の電気量密度が、５．０Ｃ／ｄｍ２以上である、上記［４］または［５］に記載の缶用鋼板の製造方法。
［７］上記フッ素含有化合物が、上記水溶液中でフッ素イオンを遊離する化合物である、上記［４］～［６］のいずれかに記載の缶用鋼板の製造方法。
That is, the present invention provides the following [1] to [7].
[1] A metal chromium layer and a chromium hydrated oxide layer are provided on the surface of the steel plate in order from the steel plate side, and the amount of the metal chromium layer deposited is 50 to 200 mg/m 2 , and the chromium hydrate The amount of adhesion of the oxide layer in terms of chromium is 15 mg/m2 or more , and the metallic chromium layer includes a flat base and granular projections provided on the base, and the maximum of the granular projections is 15 mg/m2 or more. A steel sheet for cans, wherein the grain size is 100 nm or less, and the number density of the granular projections is less than 10 pieces/μm 2 .
[2] The steel sheet for cans according to [1] above, wherein the chromium hydrated oxide layer has a deposited amount in terms of chromium of more than 30 mg/m 2 .
[3] The steel sheet for cans according to [1] or [2] above, wherein the chromium hydrated oxide layer has a deposited amount of 32 mg/m 2 or more in terms of chromium.
[4] A method for producing a steel sheet for cans according to any one of [1] to [3] above, which comprises applying an aqueous solution containing a hexavalent chromium compound and a fluorine-containing compound to a steel sheet to form a cathode. Electrolytic treatment C1, anodic electrolytic treatment A1, and cathodic electrolytic treatment C2 are performed in this order, and the current density of the anodic electrolytic treatment A1 is 10.0 A/dm 2 or more, and the charge density of the anodic electrolytic treatment A1 is A method for producing a steel plate for cans, the steel plate having a temperature of 5.0 C/dm 2 or more.
[5] The method for producing a steel sheet for cans according to [4] above, wherein the amount of Cr in the aqueous solution is 0.50 mol/L or more, and the amount of F in the aqueous solution is more than 0.10 mol/L.
[6] The current density of the cathodic electrolytic treatment C2 is 20.0 A/dm 2 or more, and the charge density of the cathodic electrolytic treatment C2 is 5.0 C/dm 2 or more, [4] or [ 5], the method for manufacturing a steel sheet for cans.
[7] The method for producing a steel sheet for cans according to any one of [4] to [6] above, wherein the fluorine-containing compound is a compound that liberates fluorine ions in the aqueous solution.
本発明によれば、耐食性に優れる缶用鋼板およびその製造方法を提供できる。 ADVANTAGE OF THE INVENTION According to this invention, the steel plate for cans which is excellent in corrosion resistance and its manufacturing method can be provided.
［缶用鋼板］
図１は、缶用鋼板の一例を模式的に示す断面図である。
図１に示すように、鋼板２を有する。缶用鋼板１は、更に、鋼板２の表面に、鋼板２側から順に、金属クロム層３およびクロム水和酸化物層４を有する。
金属クロム層３は、鋼板２を覆う平板状の基部３ａと、基部３ａ上に設けられた粒状突起３ｂとを含む。クロム水和酸化物層４は、粒状突起３ｂの形状に追従するように、金属クロム層３上に配置される。
[Steel plate for cans]
FIG. 1 is a cross-sectional view schematically showing an example of a steel plate for cans.
As shown in FIG. 1, it has a steel plate 2. The steel sheet for cans 1 further has a metal chromium layer 3 and a chromium hydrated oxide layer 4 on the surface of the steel sheet 2 in this order from the steel sheet 2 side.
The metal chromium layer 3 includes a flat base 3a that covers the steel plate 2, and granular protrusions 3b provided on the base 3a. The chromium hydrated oxide layer 4 is arranged on the metal chromium layer 3 so as to follow the shape of the granular projections 3b.
以下、缶用鋼板の各構成について、より詳細に説明する。 Hereinafter, each structure of the steel plate for cans will be explained in more detail.
〈鋼板〉
鋼板の種類は特に限定されない。通常、容器材料として使用される鋼板（例えば、低炭素鋼板、極低炭素鋼板）を使用できる。鋼板の製造方法、材質なども特に限定されない。通常の鋼片製造工程から熱間圧延、酸洗、冷間圧延、焼鈍、調質圧延等の工程を経て製造される。
<Steel plate>
The type of steel plate is not particularly limited. Steel plates (for example, low carbon steel plates, ultra-low carbon steel plates) that are normally used as container materials can be used. The manufacturing method and material of the steel plate are not particularly limited either. It is manufactured through normal steel billet manufacturing processes such as hot rolling, pickling, cold rolling, annealing, and temper rolling.
〈金属クロム層〉
上述した鋼板の表面には、金属クロム層が配置される。金属クロムは、鋼板の表面露出を抑えて耐食性を向上させる。
<Metallic chromium layer>
A metallic chromium layer is arranged on the surface of the steel plate mentioned above. Metallic chromium suppresses surface exposure of steel sheets and improves corrosion resistance.
《付着量》
缶用鋼板の耐食性が優れるという理由から、金属クロム層の付着量は、５０ｍｇ／ｍ２以上であり、６０ｍｇ／ｍ２以上が好ましく、７０ｍｇ／ｍ２以上がより好ましい。付着量は、鋼板の片面当たりの付着量である（以下、同様）。
《Amount of adhesion》
Since the corrosion resistance of the steel sheet for cans is excellent, the amount of the metal chromium layer deposited is 50 mg/m 2 or more, preferably 60 mg/m 2 or more, and more preferably 70 mg/m 2 or more. The amount of adhesion is the amount of adhesion per one side of the steel plate (the same applies hereinafter).
ところで、缶用鋼板は、その表面が塗料やフィルムなどの有機樹脂で被覆された後、製缶加工される場合がある。
金属クロム量が多すぎると、有機樹脂との密着性（以下、単に「密着性」ともいう）が、製缶加工後に不十分となる場合がある。
缶用鋼板の製缶加工後の密着性が優れるという理由から、金属クロム層の付着量は、２００ｍｇ／ｍ２以下であり、１８０ｍｇ／ｍ２以下が好ましく、１６０ｍｇ／ｍ２以下がより好ましく、１３４ｍｇ／ｍ２以下が更に好ましい。
Incidentally, a steel sheet for cans is sometimes processed into cans after its surface is coated with an organic resin such as a paint or a film.
If the amount of metallic chromium is too large, the adhesion with the organic resin (hereinafter also simply referred to as "adhesion") may become insufficient after can manufacturing.
Because the adhesion of the steel sheet for cans after can manufacturing is excellent, the amount of the metal chromium layer deposited is 200 mg/m 2 or less, preferably 180 mg/m 2 or less, more preferably 160 mg/m 2 or less, More preferably, it is 134 mg/m 2 or less.
（付着量の測定方法）
金属クロム層の付着量、および、後述するクロム水和酸化物層のクロム換算の付着量は、次のようにして測定する。
まず、金属クロム層およびクロム水和酸化物層を形成させた缶用鋼板について、蛍光Ｘ線装置を用いて、クロム量（全クロム量）を測定する。次いで、缶用鋼板を９０℃の７．５Ｎ－ＮａＯＨ中に１０分間浸漬させるアルカリ処理を行なってから、再び、蛍光Ｘ線装置を用いて、クロム量（アルカリ処理後クロム量）を測定する。アルカリ処理後クロム量を、金属クロム層の付着量とする。
次に、（アルカリ可溶性クロム量）＝（全クロム量）－（アルカリ処理後クロム量）を計算し、アルカリ可溶性クロム量を、クロム水和酸化物層のクロム換算の付着量とする。
(Method of measuring adhesion amount)
The deposited amount of the metallic chromium layer and the deposited amount of the chromium hydrated oxide layer (described later) in terms of chromium are measured as follows.
First, the amount of chromium (total amount of chromium) is measured using a fluorescent X-ray device on a steel sheet for cans on which a metallic chromium layer and a chromium hydrated oxide layer are formed. Next, the can steel plate is subjected to an alkali treatment by immersing it in 7.5N-NaOH at 90° C. for 10 minutes, and then the amount of chromium (the amount of chromium after the alkali treatment) is measured again using a fluorescent X-ray device. The amount of chromium after the alkali treatment is taken as the amount of deposited metal chromium layer.
Next, (alkali-soluble chromium amount) = (total chromium amount) - (chromium amount after alkali treatment) is calculated, and the alkali-soluble chromium amount is taken as the attached amount of the chromium hydrated oxide layer in terms of chromium.
このような金属クロム層は、平板状の基部と、基部上に設けられた粒状突起と、を含む。次に、金属クロム層が含むこれらの各部について、詳細に説明する。 Such a metal chromium layer includes a flat base and granular protrusions provided on the base. Next, each of these parts included in the metal chromium layer will be explained in detail.
《基部》
金属クロム層の基部は、主に、鋼板の表面を被覆し、耐食性を向上させる。
金属クロム層の基部は、ハンドリング時に不可避的に缶用鋼板どうしが接触した際に、表層に設けられた粒状突起が基部を破壊して鋼板が露出しないように、充分な厚みを確保していることが好ましい。
缶用鋼板の耐食性が優れるという理由から、金属クロム層の基部の付着量は、３０ｍｇ／ｍ２以上が好ましく、４０ｍｇ／ｍ２以上がより好ましい。
"base"
The base of the metal chromium layer mainly covers the surface of the steel plate and improves corrosion resistance.
The base of the metal chromium layer is sufficiently thick to prevent the granular protrusions provided on the surface layer from destroying the base and exposing the steel plates when the can steel plates inevitably come into contact with each other during handling. It is preferable.
Since the corrosion resistance of the steel sheet for cans is excellent, the amount of the metal chromium layer deposited on the base is preferably 30 mg/m 2 or more, more preferably 40 mg/m 2 or more.
《粒状突起》
金属クロム層の粒状突起は、上述した基部の表面に形成されており、例えば、缶用鋼板どうしの接触抵抗を低下させて溶接性を向上させる（粒状突起がクロム水和酸化物層を破壊して、溶接電流の通電点になり、接触抵抗が大幅に低下すると考えられる）。
《Granular protrusions》
The granular protrusions of the metal chromium layer are formed on the surface of the base mentioned above, and for example, they reduce the contact resistance between steel plates for cans and improve weldability (the granular protrusions destroy the chromium hydrated oxide layer). (This is considered to be the point where the welding current passes through, and the contact resistance decreases significantly.)
また、缶用鋼板を有機樹脂で被覆した場合において、粒状突起のアンカー効果によって、その有機樹脂との密着性が良好になる。 Furthermore, when a steel sheet for cans is coated with an organic resin, the anchoring effect of the granular projections improves the adhesion with the organic resin.
ところで、クロム水和酸化物層は、後述するように、耐食性などの特性を向上させる。
しかし、缶用鋼板を製缶加工する際に、粒状突起によって、クロム水和酸化物層が破壊される場合がある。この場合、製缶加工後の耐食性が不十分となり得る。
そこで、粒状突起の最大粒径を１００ｎｍ以下、かつ、粒状突起の個数密度を１０個／μｍ２未満にする。これにより、粒状突起によるクロム水和酸化物層の破壊が抑制され、製缶加工後の耐食性が優れる。
By the way, the chromium hydrated oxide layer improves properties such as corrosion resistance, as will be described later.
However, when forming steel sheets for cans, the chromium hydrated oxide layer may be destroyed by the granular protrusions. In this case, the corrosion resistance after can manufacturing may be insufficient.
Therefore, the maximum grain size of the granular projections is set to 100 nm or less, and the number density of the granular projections is set to be less than 10 pieces/μm 2 . This suppresses destruction of the chromium hydrated oxide layer due to granular protrusions, resulting in excellent corrosion resistance after can manufacturing.
更に、これにより、缶用鋼板の表面外観が優れる。これは、粒状突起が小径化したり少なくなったりすることで、粒状突起による可視光の乱反射が抑制されて、色調が均一になるためと考えられる。 Furthermore, this improves the surface appearance of the steel sheet for cans. This is thought to be because the diameter of the granular protrusions is reduced or the number of the granular protrusions is reduced, thereby suppressing the diffuse reflection of visible light by the granular protrusions, thereby making the color tone uniform.
（最大粒径）
粒状突起の最大粒径は、上述したように１００ｎｍ以下であり、缶用鋼板の表面外観がより優れるという理由から、６０ｎｍ以下が好ましく、４４ｎｍ以下がより好ましく、４０ｎｍ以下が更に好ましく、３５ｎｍ以下が特に好ましい。
下限は特に限定されず、粒状突起の最大粒径は、例えば、５ｎｍ以上である。
(Maximum particle size)
As mentioned above, the maximum grain size of the granular protrusions is 100 nm or less, and is preferably 60 nm or less, more preferably 44 nm or less, even more preferably 40 nm or less, and 35 nm or less, since the surface appearance of the steel plate for cans is more excellent. Particularly preferred.
The lower limit is not particularly limited, and the maximum grain size of the granular protrusions is, for example, 5 nm or more.
（個数密度）
粒状突起の個数密度は、上述したように１０個／μｍ２未満であり、缶用鋼板の表面外観がより優れるという理由から、８個／μｍ２以下が好ましく、６個／μｍ２以下がより好ましい。
下限は特に限定されず、粒状突起の個数密度は、例えば、１個／μｍ２以上である。
(number density)
As mentioned above, the number density of the granular protrusions is less than 10 pieces/ μm2 , and for the reason that the surface appearance of the steel plate for cans is better, it is preferably 8 pieces/ μm2 or less, and more preferably 6 pieces/μm2 or less. preferable.
The lower limit is not particularly limited, and the number density of granular projections is, for example, 1 piece/μm 2 or more.
（粒径および個数密度の測定方法）
金属クロム層の粒状突起の粒径および個数密度は、次のようにして求める。
まず、金属クロム層およびクロム水和酸化物層を形成させた缶用鋼板の表面に、カーボン蒸着を行ない、抽出レプリカ法によって観察用サンプルを作製する。その後、走査透過電子顕微鏡（ＴＥＭ）で２０，０００倍にて写真を撮影する。撮影した写真について、ソフトウェア（商品名：ＩｍａｇｅＪ）を用いて二値化して画像解析を行なうことで、粒状突起の占める面積から逆算し、真円換算として粒径および個数密度を求める。最大粒径は、５視野での最大の粒径とする。個数密度は、５視野の平均とする。
(Measurement method of particle size and number density)
The grain size and number density of the granular protrusions of the metal chromium layer are determined as follows.
First, carbon evaporation is performed on the surface of a steel plate for cans on which a metallic chromium layer and a chromium hydrated oxide layer have been formed, and a sample for observation is prepared by an extraction replica method. A photograph is then taken with a scanning transmission electron microscope (TEM) at 20,000x magnification. The taken photographs are binarized and image analyzed using software (trade name: ImageJ), and the area occupied by the granular protrusions is back calculated to determine the particle diameter and number density in terms of a perfect circle. The maximum particle size is the maximum particle size in 5 fields of view. The number density is the average of 5 visual fields.
〈クロム水和酸化物層〉
クロム水和酸化物は、鋼板の表面に金属クロムと同時に析出し、耐食性を向上させる。クロム水和酸化物は、例えば、クロム酸化物およびクロム水酸化物を含む。
<Chromium hydrated oxide layer>
Chromium hydrated oxide precipitates simultaneously with metallic chromium on the surface of steel sheets, improving corrosion resistance. Chromium hydrated oxides include, for example, chromium oxide and chromium hydroxide.
《付着量》
クロム水和酸化物層は、その付着量が多いほど、製缶加工の際に粒状突起により破壊されにくく、良好な耐食性が維持されやすい。
缶用鋼板の製缶加工後の耐食性が優れるという理由から、クロム水和酸化物層のクロム換算の付着量は、１５ｍｇ／ｍ２以上であり、３０ｍｇ／ｍ２超が好ましく、３２ｍｇ／ｍ２以上がより好ましく、３５ｍｇ／ｍ２以上が更に好ましく、４０ｍｇ／ｍ２以上が特に好ましい。
《Amount of adhesion》
The larger the amount of chromium hydrated oxide layer deposited, the more difficult it is to be destroyed by granular protrusions during can manufacturing, and the easier it is to maintain good corrosion resistance.
Because the corrosion resistance of the steel sheet for cans after can manufacturing is excellent, the amount of chromium hydrated oxide layer deposited in terms of chromium is 15 mg/m 2 or more, preferably more than 30 mg/m 2 , and 32 mg/m 2 The above is more preferable, 35 mg/m 2 or more is even more preferable, and 40 mg/m 2 or more is particularly preferable.
なお、クロム水和酸化物層は、缶用鋼板を有機樹脂で被覆した場合において、その有機樹脂との密着性にも寄与する。
もっとも、クロム水和酸化物層の付着量が多すぎると、有機樹脂との密着性が製缶加工後に不十分となる場合がある。
このため、缶用鋼板の製缶加工後の密着性が優れるという理由から、クロム水和酸化物層のクロム換算の付着量は、８０ｍｇ／ｍ２以下が好ましく、７０ｍｇ／ｍ２以下がより好ましく、６０ｍｇ／ｍ２以下が更に好ましい。
Note that the chromium hydrated oxide layer also contributes to adhesion to the organic resin when the can steel sheet is coated with the organic resin.
However, if the amount of the hydrated chromium oxide layer is too large, the adhesion with the organic resin may become insufficient after can manufacturing.
For this reason, since the adhesion of the steel sheet for cans after can manufacturing is excellent, the amount of chromium hydrated oxide layer adhered in terms of chromium is preferably 80 mg/m 2 or less, more preferably 70 mg/m 2 or less. , more preferably 60 mg/m 2 or less.
クロム水和酸化物層のクロム換算の付着量の測定方法は、上述したとおりである。 The method for measuring the adhesion amount of the chromium hydrated oxide layer in terms of chromium is as described above.
［缶用鋼板の製造方法］
次に、上述した缶用鋼板を製造する方法を説明する。
概略的には、鋼板に対して、六価クロム化合物およびフッ素含有化合物を含有する水溶液を用いて、陰極電解処理Ｃ１、陽極電解処理Ａ１および陰極電解処理Ｃ２を、この順に施す。
[Method for producing steel sheets for cans]
Next, a method of manufacturing the above-mentioned steel sheet for cans will be explained.
Generally speaking, a steel plate is subjected to cathodic electrolytic treatment C1, anodic electrolytic treatment A1, and cathodic electrolytic treatment C2 in this order using an aqueous solution containing a hexavalent chromium compound and a fluorine-containing compound.
〈水溶液〉
水溶液は、少なくとも、六価クロム化合物およびフッ素含有化合物を含有する。
<Aqueous solution>
The aqueous solution contains at least a hexavalent chromium compound and a fluorine-containing compound.
六価クロム化合物としては、例えば、三酸化クロム（ＣｒＯ３）；二クロム酸カリウム（Ｋ２Ｃｒ２Ｏ7）などの二クロム酸塩；クロム酸カリウム（Ｋ２ＣｒＯ４）などのクロム酸塩；等が挙げられる。 Examples of hexavalent chromium compounds include chromium trioxide (CrO 3 ); dichromates such as potassium dichromate (K 2 Cr 2 O 7 ); chromates such as potassium chromate (K 2 CrO 4 ); ; etc.
フッ素含有化合物としては、水溶液中で重フッ素イオンを遊離するケイフッ化水素酸の塩（ケイフッ化ナトリウム、ケイフッ化アンモニウムなど）よりも、水溶液中でフッ素イオンを遊離する化合物の方が好ましい。金属クロムの析出効率が良好であり、クロム水和酸化物層の膜厚が均一になりやすいからである。
水溶液中でフッ素イオンを遊離する化合物としては、例えば、フッ化水素酸（ＨＦ）、フッ化カリウム（ＫＦ）、フッ化ナトリウム（ＮａＦ）などが挙げられる。
As the fluorine-containing compound, a compound that releases fluorine ions in an aqueous solution is preferable to a salt of hydrofluorosilicic acid (sodium fluorosilicide, ammonium fluorosilicide, etc.) that releases heavy fluoride ions in an aqueous solution. This is because the precipitation efficiency of metallic chromium is good and the thickness of the hydrated chromium oxide layer tends to be uniform.
Examples of compounds that liberate fluorine ions in an aqueous solution include hydrofluoric acid (HF), potassium fluoride (KF), and sodium fluoride (NaF).
水溶液におけるＣｒ量は、０．３０ｍｏｌ／Ｌ以上が好ましく、０．５０ｍｏｌ／Ｌ以上がより好ましく、０．７０ｍｏｌ／Ｌ以上が更に好ましい。
一方、水溶液におけるＣｒ量は、５．００ｍｏｌ／Ｌ以下が好ましく、３．００ｍｏｌ／Ｌ以下がより好ましい。
The amount of Cr in the aqueous solution is preferably 0.30 mol/L or more, more preferably 0.50 mol/L or more, and even more preferably 0.70 mol/L or more.
On the other hand, the amount of Cr in the aqueous solution is preferably 5.00 mol/L or less, more preferably 3.00 mol/L or less.
水溶液におけるＦ量は、０．１０ｍｏｌ／Ｌ超が好ましく、０．１５ｍｏｌ／Ｌ以上がより好ましい。
一方、水溶液におけるＦ量は、４．００ｍｏｌ／Ｌ以下が好ましく、２．００ｍｏｌ／Ｌ以下がより好ましい。
The amount of F in the aqueous solution is preferably more than 0.10 mol/L, more preferably 0.15 mol/L or more.
On the other hand, the amount of F in the aqueous solution is preferably 4.00 mol/L or less, more preferably 2.00 mol/L or less.
水溶液は、更に、硫酸を含有してもよい。硫酸は、その一部または全部が、硫酸ナトリウム、硫酸カルシウム、硫酸アンモニウムなどの硫酸塩であってもよい。
水溶液中のフッ素含有化合物および硫酸は、フッ化物イオン、硫酸イオンおよび硫酸水素イオンへと解離した状態で存在する。これらは、陰極電解処理および陽極電解処理において進行する、水溶液中に存在する六価クロムイオンの還元反応および酸化反応に関与する触媒として働く。
水溶液が硫酸を含有する場合、水溶液におけるＳＯ４
２－量は、０．０００１ｍｏｌ／Ｌ以上が好ましく、０．０００３ｍｏｌ／Ｌ以上がより好ましく、０．００１０ｍｏｌ／Ｌ以上が更に好ましい。
一方、このＳＯ４
２－量は、０．１０００ｍｏｌ／Ｌ以下が好ましく、０．０５００ｍｏｌ／Ｌ以下がより好ましい。
The aqueous solution may further contain sulfuric acid. Part or all of the sulfuric acid may be a sulfate such as sodium sulfate, calcium sulfate, or ammonium sulfate.
The fluorine-containing compound and sulfuric acid in the aqueous solution exist in a dissociated state into fluoride ions, sulfate ions, and hydrogen sulfate ions. These act as catalysts involved in the reduction and oxidation reactions of hexavalent chromium ions present in the aqueous solution, which proceed in cathodic electrolysis and anodic electrolysis.
When the aqueous solution contains sulfuric acid, the amount of SO 4 2 in the aqueous solution is preferably 0.0001 mol/L or more, more preferably 0.0003 mol/L or more, and even more preferably 0.0010 mol/L or more.
On the other hand, the amount of SO 4 2- is preferably 0.1000 mol/L or less, more preferably 0.0500 mol/L or less.
陰極電解処理Ｃ１、陽極電解処理Ａ１、および、陰極電解処理Ｃ１においては、１種類の水溶液のみを用いてもよく、２種類以上の水溶液を併用してもよい。
水溶液の液温は、２０℃以上が好ましく、４０℃以上がより好ましい。一方、この液温は、８０℃以下が好ましく、６０℃以下がより好ましい。
In cathodic electrolytic treatment C1, anodic electrolytic treatment A1, and cathodic electrolytic treatment C1, only one type of aqueous solution may be used, or two or more types of aqueous solutions may be used in combination.
The temperature of the aqueous solution is preferably 20°C or higher, more preferably 40°C or higher. On the other hand, the liquid temperature is preferably 80°C or lower, more preferably 60°C or lower.
〈陰極電解処理Ｃ１〉
陰極電解処理Ｃ１は、金属クロムおよびクロム水和酸化物を析出させる。
このとき、適切な析出量とする観点から、陰極電解処理Ｃ１の電気量密度（電流密度と通電時間との積）は、３０．０Ｃ／ｄｍ２以上が好ましく、４５．０Ｃ／ｄｍ２以上がより好ましい。
一方、陰極電解処理Ｃ１の電気量密度は、７０．０Ｃ／ｄｍ２以下が好ましく、５５．０Ｃ／ｄｍ２以下がより好ましい。
陰極電解処理Ｃ１の電流密度（単位：Ａ／ｄｍ２）および通電時間（単位：ｓｅｃ．）は、上記の電気量密度から、適宜設定される。
<Cathode electrolysis treatment C1>
The cathodic electrolytic treatment C1 precipitates metallic chromium and hydrated chromium oxide.
At this time, from the viewpoint of obtaining an appropriate amount of precipitation, the charge density (product of current density and current application time) of the cathode electrolytic treatment C1 is preferably 30.0 C/dm 2 or more, and 45.0 C/dm 2 or more. More preferred.
On the other hand, the charge density of the cathode electrolytic treatment C1 is preferably 70.0 C/dm 2 or less, more preferably 55.0 C/dm 2 or less.
The current density (unit: A/dm 2 ) and energization time (unit: sec.) of the cathodic electrolytic treatment C1 are appropriately set from the above-mentioned electricity quantity density.
〈陽極電解処理Ａ１〉
陽極電解処理Ａ１は、陰極電解処理Ｃ１で析出した金属クロムを溶解させて、陰極電解処理Ｃ２における金属クロム層の粒状突起の発生サイトを形成する。
このとき、陽極電解処理Ａ１において、電流密度を１０．０Ａ／ｄｍ２以上、電気量密度を５．０Ｃ／ｄｍ２以上にする。
これにより、金属クロムの溶解が強くなり、発生サイトが減少し、粒状突起の個数密度が減少したり、粒状突起が小径化したりする。
<Anodic electrolysis treatment A1>
The anodic electrolytic treatment A1 dissolves the metallic chromium deposited in the cathodic electrolytic treatment C1 to form sites where granular protrusions of the metallic chromium layer in the cathodic electrolytic treatment C2 occur.
At this time, in the anodic electrolysis treatment A1, the current density is set to 10.0 A/dm 2 or more, and the charge density is set to 5.0 C/dm 2 or more.
This intensifies the dissolution of metallic chromium, reduces the number of generation sites, reduces the number density of granular protrusions, and reduces the diameter of granular protrusions.
ところで、陽極電解処理Ａ１では、クロム水和酸化物層も溶解する。
このとき、クロム水和酸化物層が不均一に溶解すると、続く陰極電解処理Ｃ２では、クロム水和酸化物層における局所的に溶解した部分において、優先的に金属クロムが析出して、粒状突起が形成される。この場合、粒状突起は、大径化したり、個数密度が増加したりしやすい。
しかしながら、陽極電解処理Ａ１の電流密度および電気量密度を上記範囲にすることで、クロム水和酸化物層の不均一な溶解が抑制される。これにより、粒状突起の大径化および個数密度の増加が抑制される。
更に、その結果、クロム水和酸化物層の付着量を、十分な量にすることができる。
By the way, in the anodic electrolytic treatment A1, the chromium hydrated oxide layer is also dissolved.
At this time, if the chromium hydrated oxide layer is unevenly dissolved, in the subsequent cathodic electrolytic treatment C2, metallic chromium is preferentially precipitated in the locally dissolved portions of the chromium hydrated oxide layer, resulting in granular protrusions. is formed. In this case, the granular projections tend to increase in diameter or increase in number density.
However, by setting the current density and charge density of the anodic electrolytic treatment A1 within the above ranges, non-uniform dissolution of the chromium hydrated oxide layer is suppressed. This suppresses an increase in the diameter of the granular protrusions and an increase in their number density.
Furthermore, as a result, a sufficient amount of the chromium hydrated oxide layer can be deposited.
陽極電解処理Ａ１の電流密度は、上述したように１０．０Ａ／ｄｍ２以上であり、２０．０Ａ／ｄｍ２以上が好ましく、３０．０Ａ／ｄｍ２以上がより好ましい。
上限は特に限定されず、陽極電解処理Ａ１の電流密度は、例えば、８０．０Ｃ／ｄｍ２以下であり、７０．０Ｃ／ｄｍ２以下が好ましい。
As mentioned above, the current density of the anodic electrolytic treatment A1 is 10.0 A/dm 2 or more, preferably 20.0 A/dm 2 or more, and more preferably 30.0 A/dm 2 or more.
The upper limit is not particularly limited, and the current density of the anodic electrolytic treatment A1 is, for example, 80.0 C/dm 2 or less, preferably 70.0 C/dm 2 or less.
陽極電解処理Ａ１の電気量密度は、上述したように５．０Ｃ／ｄｍ２以上であり、１０．０Ｃ／ｄｍ２以上が好ましく、１５．０Ｃ／ｄｍ２以上がより好ましく、２０．０Ｃ／ｄｍ２以上が更に好ましい。
上限は特に限定されず、陽極電解処理Ａ１の電気量密度は、例えば、４０．０Ｃ／ｄｍ２以下であり、３５．０Ｃ／ｄｍ２以下が好ましい。
As mentioned above, the electric charge density of the anodic electrolytic treatment A1 is 5.0 C/dm 2 or more, preferably 10.0 C/dm 2 or more, more preferably 15.0 C/dm 2 or more, and 20.0 C/dm 2 or more. More preferably 2 or more.
The upper limit is not particularly limited, and the electrical quantity density of the anodic electrolytic treatment A1 is, for example, 40.0 C/dm 2 or less, preferably 35.0 C/dm 2 or less.
陽極電解処理Ａ１の通電時間（単位：ｓｅｃ．）は、上記の電流密度および電気量密度から、適宜設定される。 The energization time (unit: sec.) of the anodic electrolysis treatment A1 is appropriately set from the above-mentioned current density and charge density.
〈陰極電解処理Ｃ２〉
上述したように、陰極電解処理は、金属クロムおよびクロム水和酸化物を析出させる。
特に、陰極電解処理Ｃ２は、上述した発生サイトを起点として、金属クロム層の粒状突起を生成させる。更に、陰極電解処理Ｃ２は、クロム水和酸化物層の付着量を制御する。
クロム析出反応と競合する水素発生反応を効果的に抑制し、金属クロム層およびクロム水和酸化物層を効率良く析出させるという理由から、陰極電解処理Ｃ２の電流密度は、２０．０Ａ／ｄｍ２以上が好ましく、３０．０Ａ／ｄｍ２以上がより好ましい。
一方、陰極電解処理Ｃ２の電流密度は、６０．０Ａ／ｄｍ２以下が好ましく、５０．０Ａ／ｄｍ２以下がより好ましい。
<Cathode electrolysis treatment C2>
As mentioned above, cathodic electrolysis precipitates metallic chromium and hydrated chromium oxide.
In particular, the cathodic electrolytic treatment C2 generates granular protrusions of the metallic chromium layer starting from the above-mentioned generation sites. Furthermore, the cathodic electrolytic treatment C2 controls the amount of chromium hydrated oxide layer deposited.
The current density of the cathodic electrolytic treatment C2 was set at 20.0 A/dm 2 because it effectively suppresses the hydrogen generation reaction that competes with the chromium precipitation reaction and efficiently deposits the metallic chromium layer and the chromium hydrated oxide layer. The above is preferable, and 30.0 A/dm 2 or more is more preferable.
On the other hand, the current density of the cathodic electrolytic treatment C2 is preferably 60.0 A/dm 2 or less, more preferably 50.0 A/dm 2 or less.
同様の理由から、陰極電解処理Ｃ２の電気量密度は、５．０Ｃ／ｄｍ２以上が好ましく、７．０Ｃ／ｄｍ２以上がより好ましく、１０．０Ｃ／ｄｍ２以上が更に好ましい。
一方、陰極電解処理Ｃ２の電気量密度は、３０．０Ｃ／ｄｍ２以下が好ましく、２５．０Ｃ／ｄｍ２以下がより好ましく、２０．０Ｃ／ｄｍ２以下が更に好ましい。
For the same reason, the charge density of the cathode electrolytic treatment C2 is preferably 5.0 C/dm 2 or more, more preferably 7.0 C/dm 2 or more, and even more preferably 10.0 C/dm 2 or more.
On the other hand, the charge density of the cathode electrolytic treatment C2 is preferably 30.0 C/dm 2 or less, more preferably 25.0 C/dm 2 or less, and even more preferably 20.0 C/dm 2 or less.
陰極電解処理Ｃ２の通電時間（単位：ｓｅｃ．）は、上記の電流密度および電気量密度から、適宜設定される。 The energization time (unit: sec.) of the cathode electrolytic treatment C2 is appropriately set from the above-mentioned current density and charge density.
陰極電解処理Ｃ１、陽極電解処理Ａ１および陰極電解処理Ｃ２は、それぞれ、連続電解処理でなくてもよい。すなわち、工業生産上、複数の電極に分けて電解することにより不可避的に無通電浸漬時間が存在する断続電解処理であってもよい。断続電解処理の場合、トータルの電気量密度が上記範囲内であることが好ましい。 Each of the cathodic electrolytic treatment C1, the anodic electrolytic treatment A1, and the cathodic electrolytic treatment C2 does not have to be continuous electrolytic treatment. That is, in industrial production, an intermittent electrolytic treatment may be used in which a non-current immersion time inevitably exists by performing electrolysis using a plurality of electrodes. In the case of intermittent electrolytic treatment, it is preferable that the total electrical quantity density is within the above range.
以下に、実施例を挙げて本発明を具体的に説明する。ただし、本発明は以下の実施例に限定されない。 The present invention will be specifically described below with reference to Examples. However, the present invention is not limited to the following examples.
〈缶用鋼板の作製〉
０．２２ｍｍの板厚で製造した鋼板（調質度：Ｔ５ＣＡ）に対して、通常の脱脂および酸洗を施した。
次いで、この鋼板に対して、下記表１に示す水溶液のいずれかを流動セルでポンプにより１００ｍｐｍ相当で循環させ、鉛電極を使用し、下記表２に示す条件で電解処理（陰極電解処理Ｃ１、陽極電解処理Ａ１および陰極電解処理Ｃ２）を施した。電解処理を施さなかった場合は、下記表２に「－」を記載した。
こうして、缶用鋼板を作製した。作製後の缶用鋼板は、水洗し、ブロアを用いて室温で乾燥した。
<Production of steel plate for cans>
A steel plate manufactured with a thickness of 0.22 mm (temperature degree: T5CA) was subjected to normal degreasing and pickling.
Next, one of the aqueous solutions shown in Table 1 below was circulated through a flow cell using a pump at a rate equivalent to 100 mpm, and the steel plate was subjected to electrolytic treatment (cathode electrolytic treatment C1, Anodic electrolytic treatment A1 and cathodic electrolytic treatment C2) were performed. When electrolytic treatment was not performed, "-" is written in Table 2 below.
In this way, a steel plate for cans was produced. The manufactured can steel plate was washed with water and dried at room temperature using a blower.
〈付着量ならびに粒状突起の最大粒径および個数密度〉
作製した缶用鋼板について、金属クロム層の付着量、および、クロム水和酸化物層のクロム換算の付着量（下記表３では単に「付着量」と表記）を測定した。
また、作製した缶用鋼板の金属クロム層について、粒状突起の最大粒径および個数密度を測定した。
測定方法は、いずれも上述したとおりである。結果を下記表３に示す。粒状突起が観察されなかった場合は、下記表３に「－」を記載した。
<Amount of adhesion, maximum particle size and number density of granular protrusions>
Regarding the produced steel sheets for cans, the amount of deposited metal chromium layer and the amount of chromium hydrated oxide layer deposited in terms of chromium (in Table 3 below, simply referred to as "deposition amount") were measured.
In addition, the maximum grain size and number density of granular protrusions were measured for the metal chromium layer of the manufactured steel sheet for cans.
All measurement methods were as described above. The results are shown in Table 3 below. If no granular protrusions were observed, "-" was written in Table 3 below.
〈評価〉
作製した缶用鋼板について、以下の評価を行なった。評価結果は下記表３に示す。
<evaluation>
The produced steel sheet for cans was evaluated as follows. The evaluation results are shown in Table 3 below.
《表面外観》
作製した缶用鋼板について、旧ＪＩＳ Ｚ ８７３０（１９８０）において規定されるハンター式色差測定に基づいて、Ｌ値を測定した。缶用鋼板ごとに、任意の１０部位でＬ値を測定し、その平均値および標準偏差値σを求め、下記基準に従い評価した。実用上、「◎」または「○」であれば、表面外観に優れると評価できる。
◎：７０≦Ｌ値の平均値、σ≦１
○：６７≦Ｌ値の平均値＜７０、１＜σ≦３
×：Ｌ値の平均値＜６７、３＜σ
《Surface appearance》
The L value of the produced steel plate for cans was measured based on the Hunter color difference measurement specified in the old JIS Z 8730 (1980). For each steel plate for cans, the L value was measured at 10 arbitrary locations, and the average value and standard deviation value σ were determined and evaluated according to the following criteria. In practical terms, if the score is "◎" or "○", it can be evaluated that the surface appearance is excellent.
◎: 70≦Average value of L value, σ≦1
○: 67≦average value of L value<70, 1<σ≦3
×: Average value of L value<67, 3<σ
《製缶加工後の特性》
作製した缶用鋼板を有機樹脂（延伸フィルム）で被覆してから、金属缶（シームレス缶）を作製し、耐食性および密着性を評価した。具体的には、以下のとおりである。
《Characteristics after can manufacturing process》
After covering the produced steel sheet for cans with an organic resin (stretched film), metal cans (seamless cans) were produced, and corrosion resistance and adhesion were evaluated. Specifically, it is as follows.
（有機樹脂被覆鋼板の作製）
作製した缶用鋼板の一方の片面（金属缶の内面となる面）上に、厚さ１９μｍの延伸フィルム１を、他方の片面（金属缶の外面となる面）上に、厚さ１３μｍの延伸フィルム２を、それぞれ、ラミネートロールを介して熱圧着させた。
延伸フィルム１は、ポリエチレンテレフタレートおよびイソフタレートの共重合組成を有し、１１モル％のイソフタル酸成分を含有する、延伸フィルムである。
延伸フィルム２は、ポリエチレンテレフタレートおよびイソフタレートの共重合組成を有し、１２モル％のイソフタル酸成分を含有する、延伸フィルムである。延伸フィルム２は、更に、酸化チタンを含有することにより、ホワイトに着色している。
熱圧着後、直ちに水冷することにより、延伸フィルムに適度な配向状態が残るように留意しながら、有機樹脂被覆鋼板を得た。得られた有機樹脂被覆鋼板は、後述する金属缶（シームレス缶）の作製に使用した。
(Production of organic resin coated steel sheet)
A stretched film 1 with a thickness of 19 μm was placed on one side (the surface that would become the inner surface of the metal can) of the manufactured steel sheet for cans, and a stretched film 1 with a thickness of 13 μm was placed on the other side (the surface that would be the outside surface of the metal can). Films 2 were each bonded by thermocompression via a laminating roll.
Stretched film 1 is a stretched film having a copolymer composition of polyethylene terephthalate and isophthalate and containing 11 mol% of an isophthalic acid component.
Stretched film 2 is a stretched film having a copolymer composition of polyethylene terephthalate and isophthalate, and containing 12 mol % of an isophthalic acid component. The stretched film 2 is colored white by further containing titanium oxide.
Immediately after thermocompression bonding, water cooling was performed to obtain an organic resin-coated steel sheet, with care being taken so that an appropriate orientation state remained in the stretched film. The obtained organic resin-coated steel sheet was used for producing a metal can (seamless can), which will be described later.
（金属缶の作製）
得られた有機樹脂被覆鋼板を、その両面にパラフィンワックスを塗布してから、直径１４３ｍｍの円形に打ち抜いた。円形に打ち抜かれた有機樹脂被覆鋼板を用いて、定法に従い、径９１ｍｍ、高さ３６ｍｍの絞りカップを作製した。
次いで、作製した絞りカップを、同時絞りしごき加工を２回繰り返すことによって、径が小さく高さの大きいカップに成形した。得られたカップの諸特性を、以下に示す。
カップ径：５２．０ｍｍ
カップ高さ：１１１．７ｍｍ
元板厚に対する板厚減少率（缶側壁部）：３０％
得られたカップをドーミング成形した後、延伸フィルムの歪みを除去するために、２２０℃で６０秒間の熱処理を実施した。続いて、カップの開口端をトリミング加工してから、曲面印刷した。その後、直径が５０．８ｍｍとなるようにネックイン加工し、更に、フランジ加工をした。こうして、２００ｍＬ用の金属缶（シームレス缶）を得た。
(Production of metal can)
The obtained organic resin-coated steel plate was coated with paraffin wax on both sides, and then punched out into a circular shape with a diameter of 143 mm. A drawing cup with a diameter of 91 mm and a height of 36 mm was produced using an organic resin-coated steel plate punched into a circular shape according to a standard method.
Next, the produced drawing cup was formed into a cup having a small diameter and a large height by repeating the simultaneous drawing and ironing process twice. The various properties of the obtained cup are shown below.
Cup diameter: 52.0mm
Cup height: 111.7mm
Thickness reduction rate relative to original thickness (can side wall): 30%
After doming the obtained cup, heat treatment was performed at 220° C. for 60 seconds to remove distortion of the stretched film. Next, the open end of the cup was trimmed, and then curved surfaces were printed. Thereafter, neck-in processing was performed so that the diameter was 50.8 mm, and further flange processing was performed. In this way, a 200 mL metal can (seamless can) was obtained.
（耐食性）
得られたシームレス缶の缶側壁部を、試験片として切り出した。試験片の端部を、テープで被覆した。その後、試験片における缶下部から５０ｍｍの部分に、カッターを用いて、長さ４ｃｍのクロスカットを入れた。クロスカットを入れた試験片を、市販のコーヒー（商品名：Ｂｌｅｎｄｙ・ボトルコーヒー低糖、味の素ゼネラルフーズ社製）に浸漬し、３７℃に保持した状態で、４週間経過させた。その後、クロスカット部からの変色の広がり（片側あたり）を測定し、下記基準に従い評価した。実用上、「◎◎」、「◎」または「○」であれば、耐食性に優れると評価できる。
◎◎：０．３ｍｍ未満
◎：０．３ｍｍ以上０．５ｍｍ未満
○：０．５ｍｍ以上１ｍｍ未満
△：１ｍｍ以上２ｍｍ未満
×：２ｍｍ以上
(corrosion resistance)
The can side wall portion of the obtained seamless can was cut out as a test piece. The ends of the specimens were covered with tape. Thereafter, a cross cut with a length of 4 cm was made using a cutter at a portion of the test piece 50 mm from the bottom of the can. The cross-cut test piece was immersed in commercially available coffee (trade name: Blendy Bottle Coffee Low Sugar, manufactured by Ajinomoto General Foods) and kept at 37°C for 4 weeks. Thereafter, the spread of discoloration from the cross-cut portion (per side) was measured and evaluated according to the following criteria. In practical terms, if the rating is "◎◎", "◎" or "○", it can be evaluated as having excellent corrosion resistance.
◎◎: Less than 0.3mm ◎: 0.3mm or more and less than 0.5mm ○: 0.5mm or more and less than 1mm △: 1mm or more and less than 2mm ×: 2mm or more
（密着性）
得られたシームレス缶の缶側壁部の外面（缶上部から１５ｍｍの部分）に、直線状の切れ目を入れた。その後、引張試験機を用いて、延伸フィルムを缶高さ方向（１８０度方向）に引き剥がし、その際の最大引張強さを測定し、下記基準に従い評価した。実用上、「◎」または「○」であれば、密着性に優れると評価できる。
◎：３．０Ｎ／１５ｍｍ以上
○：０．５Ｎ／１５ｍｍ以上３．０Ｎ／１５ｍｍ未満
×：０．５Ｎ／１５ｍｍ未満
(Adhesion)
A linear cut was made on the outer surface of the side wall of the obtained seamless can (15 mm from the top of the can). Thereafter, the stretched film was peeled off in the can height direction (180 degree direction) using a tensile testing machine, and the maximum tensile strength at that time was measured and evaluated according to the following criteria. In practical terms, if it is ``◎'' or ``○'', it can be evaluated as having excellent adhesion.
◎: 3.0N/15mm or more ○: 0.5N/15mm or more but less than 3.0N/15mm ×: Less than 0.5N/15mm
〈評価結果まとめ〉
上記表３に示す結果は、以下のとおりであった。
<Summary of evaluation results>
The results shown in Table 3 above were as follows.
《比較例１～４の説明》
クロム水和酸化物層の付着量が１５ｍｇ／ｍ２未満である比較例１は、製缶加工後の耐食性が不十分であった。
クロム水和酸化物層の付着量が１５ｍｇ／ｍ２未満であり、粒状突起の最大粒径が１００ｎｍ超であり、かつ、粒状突起の個数密度が１０個／μｍ２以上である比較例２～４は、製缶加工後の耐食性が不十分であった。
《Explanation of Comparative Examples 1 to 4》
Comparative Example 1, in which the amount of chromium hydrated oxide layer deposited was less than 15 mg/m 2 , had insufficient corrosion resistance after can manufacturing.
Comparative example 2 to which the adhesion amount of the chromium hydrated oxide layer is less than 15 mg/ m2 , the maximum grain size of the granular protrusions is more than 100 nm, and the number density of the granular protrusions is 10 pieces/μm2 or more No. 4 had insufficient corrosion resistance after can manufacturing.
《実施例１～２０の説明》
クロム水和酸化物層の付着量が１５ｍｇ／ｍ２以上であり、粒状突起の最大粒径が１００ｎｍ以下であり、かつ、粒状突起の個数密度が１０個／μｍ２未満である実施例１～２０の缶用鋼板は、比較例１～４と比較して、製缶加工後の耐食性に優れていた。
更に、実施例１～２０の缶用鋼板は、表面外観に優れ、かつ、製缶加工後の密着性も良好であった。
《Description of Examples 1 to 20》
Examples 1 to 3 in which the amount of chromium hydrated oxide layer deposited is 15 mg/ m2 or more, the maximum grain size of the granular protrusions is 100 nm or less, and the number density of the granular protrusions is less than 10 pieces/ μm2 . Can steel sheet No. 20 had excellent corrosion resistance after can manufacturing compared to Comparative Examples 1 to 4.
Furthermore, the steel sheets for cans of Examples 1 to 20 had excellent surface appearance and good adhesion after can manufacturing.
金属クロム層の付着量が１３４ｍｇ／ｍ２以下である各実施例（実施例８を除く）は、これを満たさない実施例９、１５および１８よりも製缶加工後の密着性がより良好であった。 Each example (excluding Example 8) in which the amount of adhesion of the metallic chromium layer was 134 mg/m2 or less had better adhesion after can manufacturing than Examples 9, 15, and 18 that did not satisfy this. there were.
クロム水和酸化物層の付着量が３２ｍｇ／ｍ２以上である実施例６～８、１１、１４、１７および２０は、これを満たさない各実施例と比較して、製缶加工後の耐食性がより良好であった。
このうち、実施例７～８は、製缶加工後の耐食性が更に良好であった。
ただし、製缶加工後の密着性については、実施例８よりも、クロム水和酸化物層の付着量が少ない実施例７の方が良好であった。
Examples 6 to 8, 11, 14, 17, and 20, in which the amount of chromium hydrated oxide layer deposited is 32 mg/m2 or more, have better corrosion resistance after can manufacturing than the examples that do not satisfy this. was better.
Among these, Examples 7 and 8 had even better corrosion resistance after can manufacturing.
However, in terms of adhesion after can manufacturing, Example 7, which had a smaller amount of chromium hydrated oxide layer deposited, was better than Example 8.
粒状突起の最大粒径が４４ｎｍ以下であり、かつ、粒状突起の個数密度が６個／μｍ２以下である各実施例は、これらのいずれか一方または両方を満たさない実施例４、９、１２、１５、１８および１９と比較して、表面外観がより良好であった。 Examples in which the maximum grain size of the granular protrusions is 44 nm or less and the number density of the granular protrusions is 6 pieces/μm 2 or less are Examples 4, 9, and 12 that do not satisfy either or both of these. , 15, 18 and 19, the surface appearance was better.
１：缶用鋼板
２：鋼板
３：金属クロム層
３ａ：基部
３ｂ：粒状突起
４：クロム水和酸化物層
1: Steel plate for cans 2: Steel plate 3: Metallic chromium layer 3a: Base 3b: Granular projections 4: Chromium hydrated oxide layer
Claims (5)
前記金属クロム層の付着量が、５０～２００ｍｇ／ｍ２であり、
前記クロム水和酸化物層のクロム換算の付着量が、３２ｍｇ／ｍ２以上であり、
前記金属クロム層は、平板状の基部と、前記基部上に設けられた粒状突起と、を含み、
前記粒状突起の最大粒径が、１００ｎｍ以下であり、
前記粒状突起の個数密度が、１０個／μｍ２未満である、缶用鋼板。 A metal chromium layer and a chromium hydrated oxide layer are provided on the surface of the steel plate in order from the steel plate side,
The amount of the metal chromium layer deposited is 50 to 200 mg/m 2 ,
The chromium hydrated oxide layer has a deposited amount of chromium equivalent of 32 mg/m 2 or more,
The metal chromium layer includes a flat base and granular protrusions provided on the base,
The maximum grain size of the granular protrusions is 100 nm or less,
A steel plate for cans, wherein the number density of the granular projections is less than 10 pieces/μm 2 .
鋼板に対して、六価クロム化合物およびフッ素含有化合物を含有する水溶液を用いて、陰極電解処理Ｃ１、陽極電解処理Ａ１および陰極電解処理Ｃ２を、この順に施し、
前記陽極電解処理Ａ１の電流密度が、１０．０Ａ／ｄｍ２以上であり、
前記陽極電解処理Ａ１の電気量密度が、５．０Ｃ／ｄｍ２以上である、缶用鋼板の製造方法。 A method for manufacturing the steel sheet for cans according to claim 1 , comprising:
Using an aqueous solution containing a hexavalent chromium compound and a fluorine-containing compound, the steel plate is subjected to cathodic electrolytic treatment C1, anodic electrolytic treatment A1, and cathodic electrolytic treatment C2 in this order,
The current density of the anodic electrolytic treatment A1 is 10.0 A/dm 2 or more,
A method for manufacturing a steel sheet for cans, wherein the electrical quantity density of the anodic electrolytic treatment A1 is 5.0 C/dm 2 or more.
前記水溶液におけるＦ量が、０．１０ｍｏｌ／Ｌ超である、請求項２に記載の缶用鋼板の製造方法。 The amount of Cr in the aqueous solution is 0.50 mol/L or more,
The method for manufacturing a steel sheet for cans according to claim 2 , wherein the amount of F in the aqueous solution is more than 0.10 mol/L.
前記陰極電解処理Ｃ２の電気量密度が、５．０Ｃ／ｄｍ２以上である、請求項２または３に記載の缶用鋼板の製造方法。 The current density of the cathodic electrolytic treatment C2 is 20.0 A/dm 2 or more,
The method for manufacturing a steel sheet for cans according to claim 2 or 3 , wherein the electrical quantity density of the cathodic electrolytic treatment C2 is 5.0 C/dm 2 or more.
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| JP2000248371A (en) | 1999-02-26 | 2000-09-12 | Nkk Corp | Laminated steel sheet for non-polished general welded can |
| WO2017098991A1 (en) | 2015-12-11 | 2017-06-15 | Ｊｆｅスチール株式会社 | Steel sheet for cans and production method for steel sheet for cans |
| WO2020044714A1 (en) | 2018-08-29 | 2020-03-05 | Ｊｆｅスチール株式会社 | Steel sheet for cans, and method for producing same |
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|---|---|---|---|---|
| JPS61281899A (en) * | 1985-06-08 | 1986-12-12 | Kawasaki Steel Corp | Tin-free steel sheet for welded can and its production |
| JPS61264195A (en) * | 1985-05-16 | 1986-11-22 | Kawasaki Steel Corp | Production of tin-free steel for retort can |
| JPH03229897A (en) * | 1990-02-05 | 1991-10-11 | Kawasaki Steel Corp | Tin-free steel sheet for welded can high in surface brilliance and its production |
| JPH05287591A (en) * | 1992-04-16 | 1993-11-02 | Kawasaki Steel Corp | Tin-free steel sheet for welded can with one-surface brightness enhanced |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000248371A (en) | 1999-02-26 | 2000-09-12 | Nkk Corp | Laminated steel sheet for non-polished general welded can |
| WO2017098991A1 (en) | 2015-12-11 | 2017-06-15 | Ｊｆｅスチール株式会社 | Steel sheet for cans and production method for steel sheet for cans |
| WO2020044714A1 (en) | 2018-08-29 | 2020-03-05 | Ｊｆｅスチール株式会社 | Steel sheet for cans, and method for producing same |
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