JP3584937B1 - Hexavalent chromium-free black rust-proof coating, surface treatment solution and treatment method - Google Patents
Hexavalent chromium-free black rust-proof coating, surface treatment solution and treatment method Download PDFInfo
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- JP3584937B1 JP3584937B1 JP2004000422A JP2004000422A JP3584937B1 JP 3584937 B1 JP3584937 B1 JP 3584937B1 JP 2004000422 A JP2004000422 A JP 2004000422A JP 2004000422 A JP2004000422 A JP 2004000422A JP 3584937 B1 JP3584937 B1 JP 3584937B1
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- 238000004381 surface treatment Methods 0.000 title claims abstract description 60
- 238000011282 treatment Methods 0.000 title claims abstract description 60
- 238000000576 coating method Methods 0.000 title claims description 30
- 239000011248 coating agent Substances 0.000 title claims description 28
- 238000000034 method Methods 0.000 title claims description 25
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 74
- 239000011701 zinc Substances 0.000 claims abstract description 74
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 71
- 239000000243 solution Substances 0.000 claims abstract description 64
- 239000000463 material Substances 0.000 claims abstract description 60
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 51
- 239000010959 steel Substances 0.000 claims abstract description 51
- 238000007747 plating Methods 0.000 claims abstract description 49
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims abstract description 34
- 150000001845 chromium compounds Chemical class 0.000 claims abstract description 25
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 claims abstract description 25
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims abstract description 24
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 22
- 230000003449 preventive effect Effects 0.000 claims abstract description 21
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 20
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 20
- 239000011651 chromium Substances 0.000 claims abstract description 16
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 16
- -1 nitrate ions Chemical class 0.000 claims abstract description 15
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 14
- 150000001869 cobalt compounds Chemical class 0.000 claims abstract description 14
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims abstract description 13
- 239000007864 aqueous solution Substances 0.000 claims abstract description 12
- 235000006408 oxalic acid Nutrition 0.000 claims abstract description 12
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 10
- 229910002651 NO3 Inorganic materials 0.000 claims abstract description 9
- 238000007654 immersion Methods 0.000 claims abstract description 7
- 239000007788 liquid Substances 0.000 claims description 24
- 230000002378 acidificating effect Effects 0.000 claims description 14
- 229910052804 chromium Inorganic materials 0.000 claims description 13
- 150000007524 organic acids Chemical class 0.000 claims description 11
- 238000001035 drying Methods 0.000 claims description 8
- 239000013522 chelant Substances 0.000 claims description 6
- 229910001297 Zn alloy Inorganic materials 0.000 claims description 3
- 238000005260 corrosion Methods 0.000 abstract description 36
- 230000007797 corrosion Effects 0.000 abstract description 36
- 229910001335 Galvanized steel Inorganic materials 0.000 abstract description 25
- 239000008397 galvanized steel Substances 0.000 abstract description 25
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 abstract description 22
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 abstract description 19
- 239000002253 acid Substances 0.000 abstract description 6
- 229940085991 phosphate ion Drugs 0.000 abstract description 6
- 229910019142 PO4 Inorganic materials 0.000 abstract description 5
- 239000010452 phosphate Substances 0.000 abstract description 4
- 229910000423 chromium oxide Inorganic materials 0.000 abstract description 2
- 229910001392 phosphorus oxide Inorganic materials 0.000 abstract description 2
- VSAISIQCTGDGPU-UHFFFAOYSA-N tetraphosphorus hexaoxide Chemical compound O1P(O2)OP3OP1OP2O3 VSAISIQCTGDGPU-UHFFFAOYSA-N 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 31
- 239000000047 product Substances 0.000 description 12
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 9
- MEFBJEMVZONFCJ-UHFFFAOYSA-N molybdate Chemical compound [O-][Mo]([O-])(=O)=O MEFBJEMVZONFCJ-UHFFFAOYSA-N 0.000 description 9
- 229910017604 nitric acid Inorganic materials 0.000 description 9
- 241001163841 Albugo ipomoeae-panduratae Species 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 150000003839 salts Chemical class 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 150000001875 compounds Chemical class 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- XTEGARKTQYYJKE-UHFFFAOYSA-M Chlorate Chemical compound [O-]Cl(=O)=O XTEGARKTQYYJKE-UHFFFAOYSA-M 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 229910001430 chromium ion Inorganic materials 0.000 description 4
- 229910001429 cobalt ion Inorganic materials 0.000 description 4
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 description 4
- 239000008119 colloidal silica Substances 0.000 description 4
- 238000004040 coloring Methods 0.000 description 4
- 150000002736 metal compounds Chemical class 0.000 description 4
- 239000007800 oxidant agent Substances 0.000 description 4
- 235000021317 phosphate Nutrition 0.000 description 4
- 229910021555 Chromium Chloride Inorganic materials 0.000 description 3
- 229910000640 Fe alloy Inorganic materials 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 3
- QSWDMMVNRMROPK-UHFFFAOYSA-K chromium(3+) trichloride Chemical compound [Cl-].[Cl-].[Cl-].[Cr+3] QSWDMMVNRMROPK-UHFFFAOYSA-K 0.000 description 3
- ABXXWVKOBZHNNF-UHFFFAOYSA-N chromium(3+);dioxido(dioxo)chromium Chemical group [Cr+3].[Cr+3].[O-][Cr]([O-])(=O)=O.[O-][Cr]([O-])(=O)=O.[O-][Cr]([O-])(=O)=O ABXXWVKOBZHNNF-UHFFFAOYSA-N 0.000 description 3
- WYYQVWLEPYFFLP-UHFFFAOYSA-K chromium(3+);triacetate Chemical compound [Cr+3].CC([O-])=O.CC([O-])=O.CC([O-])=O WYYQVWLEPYFFLP-UHFFFAOYSA-K 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- 239000012756 surface treatment agent Substances 0.000 description 3
- 239000011787 zinc oxide Substances 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 150000008064 anhydrides Chemical class 0.000 description 2
- 239000002738 chelating agent Substances 0.000 description 2
- 238000005660 chlorination reaction Methods 0.000 description 2
- PHFQLYPOURZARY-UHFFFAOYSA-N chromium trinitrate Chemical compound [Cr+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O PHFQLYPOURZARY-UHFFFAOYSA-N 0.000 description 2
- 229940044175 cobalt sulfate Drugs 0.000 description 2
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 2
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 2
- 150000004683 dihydrates Chemical class 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- KFZAUHNPPZCSCR-UHFFFAOYSA-N iron zinc Chemical compound [Fe].[Zn] KFZAUHNPPZCSCR-UHFFFAOYSA-N 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- KDYFGRWQOYBRFD-UHFFFAOYSA-N succinic acid Chemical compound OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 239000004640 Melamine resin Substances 0.000 description 1
- 229920000877 Melamine resin Polymers 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 241000872198 Serjania polyphylla Species 0.000 description 1
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 description 1
- 229910007570 Zn-Al Inorganic materials 0.000 description 1
- 229910007567 Zn-Ni Inorganic materials 0.000 description 1
- 229910007614 Zn—Ni Inorganic materials 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000011260 aqueous acid Substances 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical class OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- UBFMILMLANTYEU-UHFFFAOYSA-H chromium(3+);oxalate Chemical compound [Cr+3].[Cr+3].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O UBFMILMLANTYEU-UHFFFAOYSA-H 0.000 description 1
- GRWVQDDAKZFPFI-UHFFFAOYSA-H chromium(III) sulfate Chemical compound [Cr+3].[Cr+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O GRWVQDDAKZFPFI-UHFFFAOYSA-H 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 229940011182 cobalt acetate Drugs 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- GVPFVAHMJGGAJG-UHFFFAOYSA-L cobalt dichloride Chemical compound [Cl-].[Cl-].[Co+2] GVPFVAHMJGGAJG-UHFFFAOYSA-L 0.000 description 1
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 1
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 1
- MULYSYXKGICWJF-UHFFFAOYSA-L cobalt(2+);oxalate Chemical compound [Co+2].[O-]C(=O)C([O-])=O MULYSYXKGICWJF-UHFFFAOYSA-L 0.000 description 1
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 150000001991 dicarboxylic acids Chemical class 0.000 description 1
- CMMUKUYEPRGBFB-UHFFFAOYSA-L dichromic acid Chemical compound O[Cr](=O)(=O)O[Cr](O)(=O)=O CMMUKUYEPRGBFB-UHFFFAOYSA-L 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 150000002691 malonic acids Chemical class 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000002816 nickel compounds Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 150000002913 oxalic acids Chemical class 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000000682 scanning probe acoustic microscopy Methods 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000001384 succinic acid Substances 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- YONPGGFAJWQGJC-UHFFFAOYSA-K titanium(iii) chloride Chemical compound Cl[Ti](Cl)Cl YONPGGFAJWQGJC-UHFFFAOYSA-K 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2222/00—Aspects relating to chemical surface treatment of metallic material by reaction of the surface with a reactive medium
- C23C2222/10—Use of solutions containing trivalent chromium but free of hexavalent chromium
Landscapes
- Chemical Treatment Of Metals (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Abstract
【課題】クロメート皮膜に匹敵する黒色外観と良好な耐食性を併せ持つ、６価クロムフリーの黒色防錆皮膜を亜鉛系めっき鋼材の表面に形成する。特に、ジンケート浴のみならず塩化浴で電気めっきした場合にも有効な手段を提供する。
【解決手段】３価クロム化合物、コバルト化合物、シュウ酸、リン酸、および硫酸を含有し、６価クロムと硝酸イオンを含有しない酸性水溶液からなり、水溶液中のリン酸イオン／硫酸イオンの質量比が１より大である表面処理液を用いて、亜鉛系めっき鋼材に反応型の浸漬処理を行うと、耐食性に優れた黒色防錆皮膜が形成される。この皮膜は、めっき表面との界面の亜鉛の低次酸化物を含んだ黒色層と、その上のリン酸塩層と、最上層の亜鉛を含有しないクロム／リンの酸化物層の３層からなる皮膜構造を有する。その上に、有機または無機オーバーコート層を形成してもよい。
A hexavalent chromium-free black rust preventive film having both a black appearance comparable to a chromate film and good corrosion resistance is formed on the surface of a galvanized steel material. In particular, the present invention provides an effective means not only in a zincate bath but also in a chloride bath.
An acid aqueous solution containing a trivalent chromium compound, a cobalt compound, oxalic acid, phosphoric acid, and sulfuric acid and containing no hexavalent chromium and nitrate ions, and has a phosphate ion / sulfate ion mass ratio in the aqueous solution. When a reactive type immersion treatment is performed on a zinc-based plated steel material using a surface treatment solution having a value of greater than 1, a black rust-resistant film having excellent corrosion resistance is formed. This film consists of three layers: a black layer containing a lower oxide of zinc at the interface with the plating surface, a phosphate layer thereon, and a chromium / phosphorus oxide layer containing no zinc. It has a film structure of An organic or inorganic overcoat layer may be formed thereon.
Description
本発明は、６価クロム化合物を使用せずに、鋼板からボルトやナットといった小物製品までを含む多様な亜鉛系めっき鋼材の表面に、均一に真っ黒の美麗で高級感のある黒色防錆皮膜を形成する技術に関する。より詳しくは、本発明は、そのような黒色防錆皮膜を有す６価クロムフリーの黒色化亜鉛系めっき鋼材、ならびに亜鉛系めっき上にそのような黒色防錆皮膜を形成するための表面処理液および処理方法に関する。 The present invention provides a uniform black beautiful and high-grade black rust-preventive coating on the surface of various zinc-based plated steel materials, from steel plates to small products such as bolts and nuts, without using hexavalent chromium compounds. Related to forming technology. More specifically, the present invention relates to a hexavalent chromium-free blackened zinc-based plated steel material having such a black rust-proof coating, and a surface treatment for forming such a black rust-proof coating on zinc-based plating. The present invention relates to a liquid and a processing method.
亜鉛めっき鋼材と亜鉛合金めっき鋼材とを含む亜鉛系めっき鋼材の防錆処理として、６価クロムを含有する処理液を用いたクロメート処理がある。亜鉛系めっきのままでは、亜鉛の酸化による白錆がすぐに発生するため、長期的な耐食性を得ることができない。しかし、めっき後にクロメート処理を施すことにより、亜鉛系めっき鋼材の耐食性は飛躍的に向上し、塩水噴霧（ＳＳＴ）試験における白錆発生までの時間が96〜120 時間という耐食性が亜鉛系めっき鋼材に付与される。そのため、クロメート処理は亜鉛系めっき鋼材に対して広く利用されてきた。 As a rust preventive treatment for a galvanized steel material including a galvanized steel material and a zinc alloy-plated steel material, there is a chromate treatment using a treatment solution containing hexavalent chromium. In the case of zinc-based plating, long-term corrosion resistance cannot be obtained because white rust is immediately generated by oxidation of zinc. However, by performing the chromate treatment after plating, the corrosion resistance of the zinc-based plated steel material is dramatically improved, and the corrosion resistance of the zinc-coated steel material is 96 to 120 hours until white rust occurs in the salt spray (SST) test. Granted. Therefore, chromate treatment has been widely used for galvanized steel.
クロメート処理は、６価クロム化合物であるクロム酸 (または重クロム酸) に各種の鉱酸や他の添加剤を含有させたものであって、その組成を変化させることにより、青・黄・緑・黒の４種類の色調の皮膜 (クロメート皮膜) を形成することができる。そのため、例えば、自動車メーカーにおいては、この色調の違いを利用して、左右に取り付ける部品を識別することが行われている。従って、クロメート皮膜の色は、高級感を付与するといった美観の向上だけではなく、形状が似ている部品を識別するのにも役立っている。 Chromate treatment is a treatment in which various mineral acids and other additives are added to chromic acid (or dichromic acid), which is a hexavalent chromium compound, and the blue, yellow, and green colors are changed by changing the composition.・ Coatings of four types of black (chromate coatings) can be formed. For this reason, for example, an automobile manufacturer uses this difference in color to identify components to be attached to the left and right. Therefore, the color of the chromate film is useful not only for improving the aesthetic appearance such as giving a sense of quality, but also for identifying parts having similar shapes.
クロメート皮膜の主成分は、３価クロムと６価クロムとの化合物であるクロム酸クロムである。このクロム酸クロムは、クロメート処理中にクロム酸の一部が亜鉛の溶解 (即ち、酸化) により還元されて３価クロムイオンになり、この３価クロムイオンが亜鉛表面近傍でのｐＨ上昇に伴ってまたクロム酸と結合することにより生成したものである。クロメート皮膜の形成を促進するため、クロメート処理液中の６価クロムの一部を予め３価クロムに還元した部分還元型のクロメート処理液も利用されるが、その場合でも、形成されたクロメート皮膜はクロム酸クロムを主成分とするものであることに変わりはなく、３価クロムと６価クロムの両方を含有する皮膜となる。 The main component of the chromate film is chromium chromate, which is a compound of trivalent chromium and hexavalent chromium. In the chromium chromate, a part of the chromic acid is reduced by dissolution (that is, oxidation) of the zinc during the chromate treatment to become trivalent chromium ions, and the trivalent chromium ions increase with the pH increase near the zinc surface. It is also produced by bonding with chromic acid. In order to promote the formation of a chromate film, a partially reduced type chromate treatment solution in which a part of hexavalent chromium in the chromate treatment solution is reduced in advance to trivalent chromium is also used. Is a film containing chromium chromate as a main component, and becomes a film containing both trivalent chromium and hexavalent chromium.
ところが、６価クロム化合物は発がん性があり、人体や環境に有害であるため、その使用が規制されるようになってきた。そのため、亜鉛系めっき鋼材の防錆処理についても、６価クロム化合物を含有しない、６価クロムフリー処理液の使用に切り替わりつつある。そのような６価クロムフリー処理液としては、３価クロム化合物を使用した酸性処理液と、クロム化合物を全く使用しない無機系 (例、ケイ酸系) もしくは有機系 (樹脂系) の処理液とがある。処理の目的である亜鉛系めっき鋼材の耐食性の改善という点では、３価クロム化合物を含有する酸性処理液の方が、一般に耐食性の高い皮膜を形成することができる。 However, hexavalent chromium compounds are carcinogenic and harmful to humans and the environment, and their use has been regulated. Therefore, the use of a hexavalent chromium-free treatment liquid that does not contain a hexavalent chromium compound is also being switched to the rust prevention treatment of a zinc-based plated steel material. Such a hexavalent chromium-free treatment solution includes an acidic treatment solution using a trivalent chromium compound and an inorganic (eg, silicic acid) or organic (resin) treatment solution using no chromium compound at all. There is. From the viewpoint of improving the corrosion resistance of the zinc-based plated steel material, which is the purpose of the treatment, the acidic treatment solution containing a trivalent chromium compound can generally form a film having higher corrosion resistance.
しかし、従来の３価クロム化合物を含有する酸性処理液のほとんどは、亜鉛系めっき鋼材の表面処理に用いた場合、形成された防錆皮膜が無色または淡い色調、特に黄色系の色調となり、下地の亜鉛系めっきの表面が見えるため、製品に高級感を付与することができなかった。 However, most of the conventional acidic treatment solutions containing a trivalent chromium compound, when used for surface treatment of galvanized steel materials, result in a colorless or pale color tone, especially a yellow color tone, of the formed rust-preventive film. Since the surface of the zinc-based plating was visible, it was not possible to give the product a luxury feeling.
例えば、下記特許文献１には、３価クロム化合物とシュウ酸とCoイオンとを含有する酸性処理液で亜鉛系めっき鋼材を表面処理することが記載されているが、色調に関しては全く記載がない。下記特許文献２に記載された、亜鉛または亜鉛合金上に形成された、６価クロムを含まず、３価クロムを含む防錆皮膜は、透明かつ基本的に無色であると明記されている。 For example, Patent Literature 1 below describes that a zinc-based plated steel material is surface-treated with an acidic treatment solution containing a trivalent chromium compound, oxalic acid, and Co ions, but there is no description about a color tone. . The rust-preventive film formed on zinc or a zinc alloy and containing no trivalent chromium and containing trivalent chromium, which is described in Patent Document 2 below, is specified to be transparent and basically colorless.
黒色の防錆皮膜に関して、下記特許文献３には、３価クロム化合物を用いて、６価クロムを含有しない黒色化成皮膜を形成する処理溶液が記載されている。この処理溶液は、硝酸イオンと３価クロムとのモル比 (NO3 -/Cr3+) が0.5 未満となる量で硝酸（イオン）を含有し、３価クロムはキレート剤との水性錯体の形態で存在し、さらにCoおよび／またはNiイオンを、キレート剤と難溶性の塩を形成しない状態で含有する。 Regarding a black rust-preventive film, Patent Document 3 below describes a treatment solution for forming a black chemical conversion film containing no hexavalent chromium by using a trivalent chromium compound. This treatment solution contains nitric acid (ion) in an amount such that the molar ratio of nitrate ions to trivalent chromium (NO 3 − / Cr 3+ ) is less than 0.5, and trivalent chromium is an aqueous complex of a chelating agent and an aqueous complex. It exists in a form and further contains Co and / or Ni ions in a state that does not form a sparingly soluble salt with a chelating agent.
しかし、本発明者らが特許文献３の実施例を追試したところ、確かに黒色の防錆皮膜が形成される場合もあるが、その場合でも形成された防錆皮膜は全体に均一な真っ黒な皮膜とはならず、黒色度が不十分で黒みが薄く、着色が不均一な皮膜となることが多かった。また、ジンケート浴に比べて、塩化浴により電気めっきした亜鉛系めっき鋼材を処理した場合には防錆皮膜に色が着きにくく、下地の電気亜鉛めっきに用いためっき浴がジンケート浴である場合と塩化浴である場合との間で、防錆皮膜の黒色の着色状況に大きな差を生じた。 However, when the present inventors performed additional tests on the example of Patent Document 3, there was a case where a black rust-preventive film was formed in some cases. However, even in such a case, the formed rust-preventive film was uniform and completely black. In many cases, the film did not become a film, had insufficient blackness, had a dark black color, and had uneven coloring. Also, compared to zincate baths, when a zinc-based galvanized steel material electroplated with a chloride bath is treated, the color of the rust-preventive film is less likely to be obtained, and the zincate bath is used as the plating bath used for the underlying zinc plating. There was a large difference in the state of black coloration of the rust preventive film between the case of the chlorination bath and the case of the chlorination bath.
下記特許文献４には、亜硫酸イオンの供給源と酸化性物質の供給源（例、硝酸、過酸化物等）を含む、亜鉛等の金属表面に黒色皮膜を形成するための表面処理剤が記載されている。この表面処理剤は、さらに３価クロムを含む各種金属カチオンを含有しうる。しかし、この表面処理剤から形成された皮膜は、基本的に防錆皮膜ではなく、耐食性に劣るものである。また、３価クロム化合物を含有させる場合でも、硝酸または他の酸化剤が共存するため、特許文献３に記載された酸性処理液と同様に、真っ黒の美麗な黒色皮膜を形成することはできないと考えられる。 Patent Document 4 listed below describes a surface treatment agent for forming a black film on a metal surface such as zinc, including a source of sulfite ions and a source of oxidizing substances (eg, nitric acid, peroxide, etc.). Have been. This surface treatment agent may further contain various metal cations including trivalent chromium. However, the film formed from this surface treatment agent is basically not a rust-proof film and has poor corrosion resistance. Further, even when a trivalent chromium compound is contained, since a nitric acid or other oxidizing agent coexists, a beautiful black black film cannot be formed similarly to the acidic treatment solution described in Patent Document 3. Conceivable.
亜鉛を黒く変色する方法として、モリブデン酸塩法と塩素酸塩法 (以下、モリブデン酸塩法等という) が古くから知られている。これらの方法によれば、亜鉛表面に均一で真っ黒な皮膜を形成することができる。しかし、その皮膜は、亜鉛上に別の金属が置換析出したものであるため、耐食性はクロメート皮膜に遠く及ばず、防錆皮膜であると言えるものではない。
前述したように、６価クロムを利用せずに、部品の識別を可能にする明確な色調と、クロメート皮膜に匹敵するような耐食性とを併せ持つ、有色の防錆皮膜を亜鉛系めっき鋼材の表面に形成することができる処理液の開発が望まれていた。 As described above, a colored rust-preventive film that has a distinct color tone that enables component identification and corrosion resistance comparable to a chromate film without using hexavalent chromium is applied to the surface of a galvanized steel material. There has been a demand for the development of a processing solution that can be formed on a substrate.
特に、識別を可能にする点に加えて、高級感・重量感を与える色であるという理由から、黒色の外観を持つ防錆皮膜を亜鉛系めっき鋼材の表面に形成することが、亜鉛系めっき鋼材のユーザーから強く要望されていた。この点に関して、上記特許文献３に記載された処理液から亜鉛系めっき鋼材の表面に形成された化成皮膜は、黒色度がやや薄く、しかも不均一であって、従来のモリブデン酸塩法等により形成された均一に真っ黒の黒色皮膜と比べると、黒色度が不十分であり、特に塩化浴で亜鉛めっきした場合の着色は非常に薄かった。 In particular, in addition to the point of enabling discrimination, it is necessary to form a rust-preventive film with a black appearance on the surface of galvanized steel, because it is a color that gives a sense of quality and weight. It was strongly requested by users of steel products. In this regard, the chemical conversion film formed on the surface of the zinc-based plated steel material from the treatment solution described in Patent Document 3 has a slightly thin blackness and is not uniform, and is formed by a conventional molybdate method or the like. Compared to the formed black film, which was uniformly black, the degree of blackness was insufficient, and the coloring was extremely light, especially when galvanized in a chloride bath.
本発明の課題は、従来のモリブデン酸塩法等により形成されるのと同じレベルの美麗な黒色外観と、クロメート皮膜に匹敵しうる優れた耐食性とを併せ持つ、６価クロムフリーの黒色防錆皮膜を亜鉛系めっき鋼材の表面に形成する技術を開発することである。 An object of the present invention is to provide a hexavalent chromium-free black rust preventive film having a beautiful black appearance at the same level as formed by a conventional molybdate method or the like and excellent corrosion resistance comparable to a chromate film. Is to develop a technology for forming a steel on the surface of galvanized steel.
本発明の別の課題は、ジンケート浴のみならず、塩化浴を用いた亜鉛系めっき鋼材に対しても、美麗な黒色の防錆皮膜を形成できる技術を開発することである。 Another object of the present invention is to develop a technique capable of forming a beautiful black rust-proof coating not only on a zincate bath but also on a zinc-based plated steel material using a chloride bath.
本発明者らは、耐食性の良好な皮膜を形成できることが知られている３価クロム化合物を含有する６価クロムフリーの酸性の表面処理液において、３価クロム化合物以外の成分の種類や量を選択することにより、ジンケート浴や塩化浴を含む各種のめっき手法によりめっきを施した亜鉛系めっき鋼材のめっき表面に、モリブデン酸塩法等と同様に真っ黒に見える美麗な黒色外観と、クロメート皮膜に匹敵する良好な耐食性とを併せ持つ黒色防錆皮膜を形成することができることを見出した。 The present inventors have determined that a hexavalent chromium-free acidic surface treatment solution containing a trivalent chromium compound, which is known to be capable of forming a film having good corrosion resistance, can control the types and amounts of components other than the trivalent chromium compound. Depending on the choice, a beautiful black appearance that looks black as well as a molybdate method, and a chromate film on the plating surface of galvanized steel material plated by various plating methods including zincate bath and chloride bath It has been found that it is possible to form a black rust-preventive film having comparable good corrosion resistance.
一方で、本発明者らは、従来のモリブデン酸塩法等により形成された均一で真っ黒な皮膜について、Ｌ*ａ*ｂ* 表色系の測定機器を用いて調べたところ、この種の黒色皮膜では、上記表色系の明度指数Ｌ* の値 (以下、Ｌ値という、Ｌ値が小さいほど皮膜の黒みは増す) が常に15未満であることを知った。 On the other hand, the present inventors examined a uniform and black film formed by a conventional molybdate method or the like using a measuring instrument of L * a * b * color system. It was found that the value of the lightness index L * of the color system (hereinafter referred to as the L value, the smaller the L value, the darker the film increases) is always less than 15.
また、上記特許文献３の実施例に従って形成した黒色皮膜についても同様に調べたところ、Ｌ値は15以上であり、20以上となる場合もあった。さらに、この特許文献３の実施例ではジンケート浴を用いて電気亜鉛めっきをしているが、塩化浴で電気めっきした亜鉛めっき鋼板に同様に黒色皮膜を形成したところ、Ｌ値は最低でも20を超え、場合により30以上と非常に大きかった。そして、黒色皮膜におけるＬ値と肉眼で見た黒色度とがよく相関し、Ｌ値が15未満、特に14以下であると、真っ黒に見える黒色皮膜となり、Ｌ値が20以上では灰色となり、Ｌ値が30以上では着色は非常に薄いものとなることがわかった。 In addition, when a black film formed in accordance with the example of Patent Document 3 was examined in the same manner, the L value was 15 or more, and in some cases was 20 or more. Furthermore, in the example of Patent Document 3, electrogalvanization is performed using a zincate bath. However, when a black film is formed on a galvanized steel plate electroplated in a chloride bath, the L value is at least 20. Exceeded and in some cases was very large, over 30. The L value in the black film and the degree of blackness seen by the naked eye correlate well. When the L value is less than 15, especially 14 or less, the black film looks black, and when the L value is 20 or more, it becomes gray. When the value was 30 or more, the coloring was found to be very light.
そこで、本発明者らが開発した上記の黒色防錆皮膜について、同様にＬ値を測定したところ、モリブデン酸塩法等により形成された黒色皮膜と同様に、この皮膜のＬ値は15未満、ほとんどは14以下であった。 Therefore, when the L value of the above black rust preventive film developed by the present inventors was measured in the same manner, the L value of this film was less than 15, like the black film formed by the molybdate method or the like. Most were less than 14.
ここに、本発明は、下記の通りである。
(1)亜鉛系めっき鋼材の表面に黒色防錆皮膜を形成するための酸性の表面処理液であって、３価クロム化合物、コバルト化合物、キレート形成能のある有機酸、リン酸、および硫酸を含有し、６価クロムと硝酸イオンを含有しない酸性水溶液からなり、水溶液中のリン酸イオン／硫酸イオンの質量比が１以上であることを特徴とする表面処理液。
Here, the present invention is as follows.
(1) An acidic surface treatment liquid for forming a black rust preventive film on the surface of a zinc-based plated steel material, comprising a trivalent chromium compound, a cobalt compound, an organic acid capable of forming a chelate, phosphoric acid, and sulfuric acid. A surface treatment solution comprising an acidic aqueous solution containing no hexavalent chromium and nitrate ions, wherein the mass ratio of phosphate ions / sulfate ions in the aqueous solution is 1 or more.
(2)前記有機酸がシュウ酸である、上記(1) に記載の表面処理液。
(3)液のｐＨが２〜３の範囲である、上記(1) または(2) に記載の表面処理液。
(4)亜鉛系めっき鋼材を上記 (1)〜(3) のいずれかに記載の表面処理液中に浸漬した後、乾燥して、黒色防錆皮膜をめっき表面に形成することを特徴とする、亜鉛系めっき鋼材の黒色化処理方法。
(2) The surface treatment solution according to the above (1), wherein the organic acid is oxalic acid.
(3) The surface treatment liquid according to the above (1) or (2), wherein the pH of the liquid is in the range of 2-3.
(4) The zinc-based plated steel material is immersed in the surface treatment solution according to any one of (1) to (3), and then dried to form a black rust-proof coating on the plating surface. , Blackening treatment method for galvanized steel.
(5)形成された黒色防錆皮膜の上に有機または無機オーバーコート層を形成する上記(4) に記載の亜鉛系めっき鋼材の黒色化処理方法。
(6)塩化浴を用いた電気亜鉛系めっき表面に、３価クロム化合物を含有し、６価クロムを含まない、Ｌ値が15未満の黒色防錆皮膜を有する、黒色化亜鉛系めっき鋼材。
(5) The method for blackening zinc-plated steel according to (4), wherein an organic or inorganic overcoat layer is formed on the formed black rust-preventive film.
(6) A blackened zinc-based plated steel material containing a trivalent chromium compound, excluding a hexavalent chromium, and having a black rust-proof coating having an L value of less than 15 on an electrogalvanized plating surface using a chloride bath.
(7)亜鉛系めっき表面に、上記 (1)〜(3) のいずれかに記載の表面処理液を用いた浸漬処理により形成された、６価クロムを含まず、３価クロムを含む、Ｌ値15未満の黒色防錆皮膜を有する、黒色化亜鉛系めっき鋼材。 (7) L-containing, not containing hexavalent chromium, formed on a zinc-based plating surface by immersion treatment using the surface treatment solution according to any of (1) to (3) above, A blackened zinc-based plated steel material having a black rust-proof coating with a value of less than 15.
(8)前記黒色防錆皮膜の上にさらに無色の無機または有機オーバーコート層を有する、上記(6) または(7) に記載の黒色化亜鉛系めっき鋼材。 (8) The blackened zinc-based plated steel material according to the above (6) or (7), further comprising a colorless inorganic or organic overcoat layer on the black rust preventive film.
本発明によれば、３価クロム化合物を主な皮膜形成成分とし、６価クロムを含まない処理液を利用して、６価クロムを含有するクロメート皮膜に匹敵する耐食性を示す、６価クロムフリーの黒色防錆皮膜を亜鉛系めっき鋼材のめっき表面に形成することができる。 According to the present invention, a trivalent chromium compound is used as a main film forming component, and a hexavalent chromium-free treatment liquid containing hexavalent chromium is used to exhibit corrosion resistance comparable to that of a chromate film containing hexavalent chromium. Can be formed on the plating surface of a zinc-based plated steel material.
この３価クロム系の黒色防錆皮膜は、従来のモリブデン酸塩法等により形成された黒色皮膜と同様に、Ｌ値が15未満で、肉眼で見て均一に真っ黒である。また、特許文献３に記載の技術では、塩化浴を用いて電気亜鉛めっきした鋼材にはジンケート浴に比べて黒色の色が着きにくかったが、本発明の黒色防錆皮膜は、塩化浴とジンケート浴との間で差がなく、亜鉛めっきが塩化浴である場合にも、ジンケート浴の場合と同様の真っ黒な美麗な黒色の防錆皮膜をめっき表面に形成することができる。 This trivalent chromium-based black rust-preventive film has an L value of less than 15 and is uniformly black with the naked eye, similarly to a black film formed by a conventional molybdate method or the like. Further, in the technology described in Patent Literature 3, a black color is harder to reach on a steel material electrogalvanized using a chloride bath than a zincate bath, but the black rust-preventive film of the present invention uses a chloride bath and a zincate bath. There is no difference from the bath, and even when the zinc plating is a chloride bath, it is possible to form a beautiful black black rust-proof coating on the plating surface similar to the zincate bath.
その結果、左右に取り付けるべき亜鉛系めっき鋼材製の部品を、一方は従来の無色の防錆皮膜、他方は本発明の黒色の防錆皮膜を形成することにより、肉眼で識別することが可能となり、それらを簡単に識別でき取り付け作業が容易になる上、取り付けミスを防ぐことができる。 As a result, parts made of galvanized steel to be attached to the left and right can be visually identified by forming a conventional colorless rust-proof coating on one side and the black rust-proof coating of the present invention on the other side. In addition, they can be easily identified, the mounting work can be facilitated, and mounting errors can be prevented.
また、本発明の黒色防錆皮膜は、重厚で高級感のある黒色外観を亜鉛系めっき鋼材に付与することができ、かつ下地の亜鉛系めっきの金属質の表面は完全に見えなくなる。そのため、この黒色防錆皮膜は、特に外部に見える部品や製品への適用に適しており、それらに黒色の美麗な外観を付与して、その商品価値を高めることができる。 In addition, the black rust-preventive film of the present invention can impart a thick and high-grade black appearance to a zinc-based plated steel material, and the underlying zinc-based plated metal surface is completely invisible. Therefore, this black rust-preventive film is particularly suitable for application to parts and products that are visible to the outside, and can impart a beautiful black appearance to them to enhance their commercial value.
以下に本発明をより具体的に説明する。本明細書において、％は、特に指定しない限り質量％である。
本発明は、亜鉛系めっき鋼材に６価クロムフリーの黒色防錆皮膜を形成する技術に関する。
Hereinafter, the present invention will be described more specifically. In this specification,% is% by mass unless otherwise specified.
The present invention relates to a technique for forming a hexavalent chromium-free black rust preventive film on a galvanized steel material.
めっき母材となる鋼材は、鋼板、鋼管、線材、棒材、異形材といった一次加工品でも、それらをさらに加工した部品、半加工品もしくは製品であってもよい。後者の例としては、ボルトやナットといった小物部品、プレス成形品、打抜き加工品、鍛造品、鋳造品などが例示されるが、それらに限られるものではない。 The steel material used as the plating base material may be a primary processed product such as a steel plate, a steel pipe, a wire, a bar, or a deformed material, or a part, a semi-processed product, or a product obtained by further processing the primary processed product. Examples of the latter include small parts such as bolts and nuts, press-formed products, stamped products, forged products, cast products, and the like, but are not limited thereto.
本発明において、亜鉛系めっき鋼材とは、亜鉛めっき鋼材と亜鉛合金めっき鋼材の両方を含む意味である。亜鉛合金めっきの例としては、Zn−Ni合金めっき、Zn−Fe合金めっき (合金化溶融亜鉛めっきを含む) 、Zn−Al合金めっきなどが例示される。亜鉛系めっきのめっき方法は、電気めっきでも溶融めっきでもよく、また気相めっき等の特殊なめっき方法であってもかまわない。めっき付着量も、鋼材に必要な耐食性を付与することができれば、特に制限されない。 In the present invention, the galvanized steel material includes both galvanized steel material and zinc alloy-plated steel material. Examples of zinc alloy plating include Zn-Ni alloy plating, Zn-Fe alloy plating (including galvannealed galvanizing), and Zn-Al alloy plating. The zinc-based plating method may be electroplating or hot-dip plating, or may be a special plating method such as vapor phase plating. The coating weight is not particularly limited as long as necessary corrosion resistance can be imparted to the steel material.
電気亜鉛系めっきのめっき浴は、当業者には周知のように、鋼材の種類により選択することができる。例えば、鋼板のめっきにはジンケート浴が、小物部品には塩化浴がよく使用されるが、それに限定されるものではない。上述したように、特許文献３に記載の技術とは異なり、本発明では、塩化浴を用いて電気めっきを行った亜鉛系めっき鋼材に対しても、真っ黒な美しい防錆皮膜を形成することができる。従って、塩化浴が適用されることが多い小物部品にも適用することができるので、例えば、ボルトやナットに耐食性と黒色外観の両方を同時に付与することができ、その商品価値を著しく高めることができる。 The plating bath for the electro-zinc plating can be selected according to the type of the steel material, as is well known to those skilled in the art. For example, a zincate bath is often used for plating a steel sheet, and a chloride bath is often used for small parts, but the present invention is not limited to this. As described above, unlike the technique described in Patent Document 3, in the present invention, it is possible to form a beautiful black anticorrosive film even on a zinc-based plated steel material electroplated using a chloride bath. it can. Therefore, since the present invention can be applied to small parts to which a chloride bath is often applied, for example, it is possible to simultaneously impart both corrosion resistance and a black appearance to bolts and nuts, thereby significantly increasing the commercial value. it can.
本発明で亜鉛系めっき鋼材の表面に黒色防錆皮膜を形成するのに用いる表面処理液は、３価クロム化合物、コバルト化合物、キレート形成能のある有機酸、リン酸、および硫酸を含有し、６価クロムと硝酸イオンを含有しない酸性水溶液からなる。 The surface treatment solution used to form a black rust-proof coating on the surface of the zinc-based plated steel material in the present invention contains a trivalent chromium compound, a cobalt compound, an organic acid capable of forming a chelate, phosphoric acid, and sulfuric acid, It consists of an acidic aqueous solution containing no hexavalent chromium and nitrate ions.
３価クロム化合物は、防錆皮膜の主要な皮膜形成成分である。本発明の場合、３価クロム化合物は、主に処理液中のリン酸イオンと反応して不溶性のリン酸塩を形成することにより、耐食性に優れた皮膜を形成する。３価クロム化合物としては、酸性水溶液中に可溶性の化合物を使用すればよい。そのような３価クロム化合物の例としては、塩化クロム、硫酸クロムのような無機酸塩と、酢酸クロム、シュウ酸クロムのような有機酸塩とが挙げられる。 The trivalent chromium compound is a main film forming component of the antirust film. In the case of the present invention, the trivalent chromium compound forms a film having excellent corrosion resistance by mainly reacting with phosphate ions in the treatment liquid to form an insoluble phosphate. As the trivalent chromium compound, a compound soluble in an acidic aqueous solution may be used. Examples of such trivalent chromium compounds include inorganic acid salts such as chromium chloride and chromium sulfate, and organic acid salts such as chromium acetate and chromium oxalate.
コバルト化合物も同様に酸性水溶液中に可溶性の化合物であればよい。そのようなコバルト化合物の例は、塩化コバルト、硫酸コバルトのような無機酸塩と、酢酸コバルト、シュウ酸コバルトのような有機酸塩とが挙げられる。コバルト化合物は、メカニズムは不明であるが、皮膜の黒色化に関与しており、表面処理液がコバルト化合物を含んでいないと、形成された皮膜は無色〜薄黄色となる。 Similarly, the cobalt compound may be any compound that is soluble in the acidic aqueous solution. Examples of such cobalt compounds include inorganic acid salts such as cobalt chloride and cobalt sulfate, and organic acid salts such as cobalt acetate and cobalt oxalate. Although the mechanism of the cobalt compound is unknown, it is involved in the blackening of the film, and if the surface treatment solution does not contain the cobalt compound, the formed film becomes colorless to pale yellow.
キレート形成能のある有機酸は、ジカルボン酸やヒドロキシカルボン酸を含むが、好ましくはシュウ酸、マロン酸、コハク酸といった炭素数が６以下の脂肪族ジカルボン酸であり、価格も考慮するとシュウ酸が最も好ましい。表面処理液がこの種の有機酸を含有していなくても、皮膜は形成されるが、やはり無色〜薄黄色の皮膜となり、黒色化しない。その上、この有機酸は皮膜の耐食性にも影響し、表面処理液がこの種の有機酸を含有しないと、皮膜は耐食性が非常に劣ったものとなる。以下では、キレート形成能のある有機酸をシュウ酸で代表させて、本発明を説明する。 Organic acids capable of forming chelate include dicarboxylic acids and hydroxycarboxylic acids, but are preferably oxalic acids, malonic acids, and aliphatic dicarboxylic acids having 6 or less carbon atoms such as succinic acid. Most preferred. Even if the surface treatment liquid does not contain this kind of organic acid, a film is formed, but it is still a colorless to light yellow film and does not turn black. In addition, this organic acid also affects the corrosion resistance of the coating, and if the surface treatment solution does not contain this kind of organic acid, the coating will have very poor corrosion resistance. Hereinafter, the present invention will be described using an organic acid capable of forming a chelate as oxalic acid.
リン酸と硫酸は、いずれも、適当な濃度に希釈したものを処理液の調製に使用してもよい。表面処理液がリン酸を含有せず、代わりに硝酸、硫酸および／または塩酸だけを含有している場合には、黒色度の高い皮膜は形成されない。代わりに、黒い煤状の微粒子が表面に付着した、美麗ではない (煤けた) 皮膜が形成されることが多い。 Both phosphoric acid and sulfuric acid may be used after diluting to an appropriate concentration for preparing a treatment solution. When the surface treatment liquid does not contain phosphoric acid, but instead contains only nitric acid, sulfuric acid and / or hydrochloric acid, a film having a high degree of blackness is not formed. Instead, they often form an unclean (soot) film with black soot-like particles attached to the surface.
水溶液中のリン酸イオンおよび硫酸イオンの量は、リン酸および硫酸として添加された量だけでなく、例えば、３価クロム化合物やコバルト化合物としてリン酸塩または硫酸塩を使用した場合には、そのような金属塩からアニオンとして供給されるリン酸イオンおよび硫酸イオンの量も含んだ量である。 The amounts of phosphate ions and sulfate ions in the aqueous solution are not limited to the amounts added as phosphoric acid and sulfuric acid. For example, when phosphates or sulfates are used as trivalent chromium compounds or cobalt compounds, The amount also includes the amounts of phosphate ions and sulfate ions supplied as anions from such a metal salt.
黒色の防錆皮膜を形成するには、水溶液中のリン酸イオン／硫酸イオンの質量比が１以上になるようにする。この質量比が１より小さくなって、リン酸イオンより硫酸イオンの量の方が多くなると、防錆皮膜が黒色にならずに、灰色になったり、リン酸を含有しない場合と同様に煤けたものとなることがある。この質量比が大き過ぎても、黒色度が低下することがあるので、この質量比は好ましくは５以下である。 In order to form a black rust preventive film, the mass ratio of phosphate ion / sulfate ion in the aqueous solution is adjusted to 1 or more. When the mass ratio is less than 1 and the amount of sulfate ions is larger than that of phosphate ions, the rust preventive film does not become black, but becomes gray or soots as in the case where it does not contain phosphoric acid. It may be something. If the mass ratio is too large, the blackness may decrease, so that the mass ratio is preferably 5 or less.
本発明の表面処理液は、硝酸イオンを含有しない。上記特許文献３に記載の表面処理液は硝酸を含有し、特許文献４に記載の処理液は酸化剤を含有する。本発明の表面処理液が硝酸イオンを含有すると、特許文献３に記載の表面処理液と同様に、形成された防錆皮膜の黒色度が低下し、特に塩化浴による亜鉛めっき表面においてその傾向が高くなる。従って、本発明では、表面処理液の調製に用いる成分として、遊離の硝酸だけでなく、硝酸クロムや硝酸コバルトといった硝酸イオンの供給源となる硝酸塩も使用しない。 The surface treatment liquid of the present invention does not contain nitrate ions. The surface treatment solution described in Patent Document 3 contains nitric acid, and the treatment solution described in Patent Document 4 contains an oxidizing agent. When the surface treatment solution of the present invention contains nitrate ions, similarly to the surface treatment solution described in Patent Document 3, the blackness of the formed rust-preventive film decreases, and this tendency is particularly observed on the galvanized surface by a chloride bath. Get higher. Accordingly, in the present invention, not only free nitric acid but also a nitrate serving as a source of nitrate ions such as chromium nitrate and cobalt nitrate is not used as a component used for preparing the surface treatment liquid.
表面処理液のｐＨは２〜３の範囲内であることが好ましい。ｐＨが低すぎると処理中の亜鉛めっきの溶出が多くなり、亜鉛系めっき鋼材の耐食性が低下する。ｐＨが高すぎると、皮膜形成が起こりにくくなり、黒色度も低下する傾向がある。 The pH of the surface treatment solution is preferably in the range of 2-3. If the pH is too low, the dissolution of zinc plating during processing increases, and the corrosion resistance of the zinc-based plated steel material decreases. If the pH is too high, film formation is unlikely to occur, and the blackness tends to decrease.
この表面処理液は、亜鉛系めっき浴の表面にＬ値が15未満の黒色防錆皮膜を形成することができる限り、上記成分以外に、６価クロムを含まない他の成分を含有しうる。そのような成分の例としては、液のｐＨを調整するための化合物が挙げられる。また、コバルト化合物に加えて、ニッケル化合物を併用してもよい。 This surface treatment solution may contain, in addition to the above components, other components not containing hexavalent chromium, as long as a black rust preventive film having an L value of less than 15 can be formed on the surface of the zinc-based plating bath. Examples of such components include compounds for adjusting the pH of the solution. Further, a nickel compound may be used in addition to the cobalt compound.
上記特許文献３に記載の処理液は、耐食性の向上のためにコロイダルシリカや三塩化チタンをはじめとする多様な金属種の化合物をさらに含有することができ、実際に全ての実施例においてそのような追加の金属化合物を含有させている。本発明の表面処理液にもそのような追加の金属化合物を含有させることができるが、種類によっては皮膜の性状がやや変質することがある。例えば、コロイダルシリカを表面処理液に含有させると、皮膜の光沢はやや高まるが、黒色皮膜としての高級感はやや失われる。本発明の表面処理液の場合、コロイダルシリカ等の追加の金属化合物を含有させなくても、クロメート皮膜なみの優れた耐食性を亜鉛系めっき鋼材に付与することができる。 The treatment liquid described in Patent Document 3 described above can further contain various metal species compounds such as colloidal silica and titanium trichloride for improving corrosion resistance. Additional metal compounds. The surface treatment liquid of the present invention can also contain such an additional metal compound, but depending on the type, the properties of the coating may be slightly altered. For example, when colloidal silica is contained in the surface treatment solution, the gloss of the film is slightly increased, but the sense of quality as a black film is slightly lost. In the case of the surface treatment solution of the present invention, excellent corrosion resistance comparable to a chromate film can be imparted to a galvanized steel material without adding an additional metal compound such as colloidal silica.
本発明の表面処理液中の上記各成分の含有量は、耐食性に優れた黒色皮膜が形成されるように選択すればよい。処理液中の３価クロムイオンの含有量は 0.5〜30 g/lの範囲とすることが好ましく、より好ましくは 1.5〜20 g/lの範囲である。 The content of each of the above components in the surface treatment solution of the present invention may be selected so that a black film having excellent corrosion resistance is formed. The content of trivalent chromium ions in the treatment liquid is preferably in the range of 0.5 to 30 g / l, more preferably in the range of 1.5 to 20 g / l.
シュウ酸または他のキレート形成能を有する有機酸は、３価クロム化合物とコバルト化合物、さらに存在すれば他の金属化合物が沈殿しないような量で含有させる。通常は、３価クロムイオンに対するモル比で 0.2〜４の範囲内が好ましく、このモル比はより好ましくは 0.4〜２の範囲内である。 Oxalic acid or another organic acid capable of forming a chelate is contained in such an amount that a trivalent chromium compound and a cobalt compound, and if present, other metal compounds do not precipitate. Usually, the molar ratio to the trivalent chromium ion is preferably in the range of 0.2 to 4, and the molar ratio is more preferably in the range of 0.4 to 2.
コバルト化合物の含有量は、コバルトイオンとして 0.1〜10 g/lの範囲内とすることが好ましい。この量はより好ましくは 0.3〜５g/l であり、さらに好ましく 0.5〜３g/l である。 The content of the cobalt compound is preferably in the range of 0.1 to 10 g / l as cobalt ions. This amount is more preferably from 0.3 to 5 g / l, even more preferably from 0.5 to 3 g / l.
リン酸イオンおよび硫酸イオンは、前述したように、リン酸イオン／硫酸イオンの質量比が１以上となり、かつ表面処理液のｐＨが好ましい値となる量で含有させる。
本発明の表面処理液は亜鉛系めっき鋼材の反応型化成処理に使用するものである。従って、所望の皮膜を形成するのに十分な時間、亜鉛系めっき鋼材を表面処理液に浸漬した後、乾燥することにより、表面処理を実施することができる。
As described above, the phosphate ion and the sulfate ion are contained in such an amount that the mass ratio of the phosphate ion / sulfate ion becomes 1 or more and the pH of the surface treatment solution becomes a preferable value.
The surface treatment solution of the present invention is used for reactive chemical conversion treatment of zinc-based plated steel materials. Therefore, the surface treatment can be performed by immersing the zinc-based plated steel material in the surface treatment solution for a sufficient time to form a desired film, and then drying it.
浸漬時間 (処理時間) や処理温度 (表面処理液の浴温度) といった処理条件は、十分な耐食性と黒色外観を持つ防錆皮膜が形成されるように選択すればよく、表面処理液の組成によっても適切な処理条件は異なる。処理による皮膜形成が亜鉛系めっき鋼材の全体に均一に進行するように、浸漬中に表面処理液を適当な手段 (例、揺動) により攪拌してもよい。 The treatment conditions such as immersion time (treatment time) and treatment temperature (bath temperature of the surface treatment solution) may be selected so as to form a rust-preventive film with sufficient corrosion resistance and black appearance, and depending on the composition of the surface treatment solution. The appropriate processing conditions also differ. During the immersion, the surface treatment solution may be agitated by a suitable means (eg, rocking) so that the film formation by the treatment proceeds uniformly throughout the galvanized steel material.
一般に、弱酸塩である酢酸クロムを含有する表面処理液より、強酸塩である塩化クロムを含有する表面処理液の方が、反応がより起こり易いので、処理時間を短めにするか、および／または処理温度を低めにすることができる。例えば、塩化クロムを含有する表面処理液では、処理時間を30〜120 秒、処理温度を20〜70℃とすることが好ましい。一方、酢酸クロム (または他の３価クロム有機酸塩) を含有する表面処理液の場合は、処理時間を60〜180 秒、処理温度は40〜70℃とすることが好ましい。但し、Ｌ値が15未満の防錆性に優れた黒色防錆皮膜が形成できれば、処理条件はこの範囲外であってもよい。 In general, a surface treatment solution containing chromium chloride, which is a strong acid salt, is more likely to react than a surface treatment solution containing chromium acetate, which is a weak acid salt, so that the treatment time is shortened, and / or The processing temperature can be lowered. For example, for a surface treatment solution containing chromium chloride, the treatment time is preferably 30 to 120 seconds, and the treatment temperature is preferably 20 to 70 ° C. On the other hand, in the case of a surface treatment solution containing chromium acetate (or another trivalent chromium organic acid salt), the treatment time is preferably 60 to 180 seconds, and the treatment temperature is preferably 40 to 70 ° C. However, the processing conditions may be outside this range as long as a black rust preventive film having an L value of less than 15 and excellent in rust prevention can be formed.
処理を受ける亜鉛系めっき鋼材は、クロメート処理の場合と同様の前処理を予め施しておくことが好ましい。この前処理は、例えば、まず亜鉛系めっき鋼材を水洗した後、塩酸、硝酸、硫酸といった鉱酸の水溶液に浸漬して、めっき表面を活性化させ、再び水洗することにより実施できる。 It is preferable that the zinc-based plated steel material to be subjected to the treatment is previously subjected to the same pretreatment as in the case of the chromate treatment. This pretreatment can be performed, for example, by first washing the zinc-based plated steel material with water, immersing it in an aqueous solution of a mineral acid such as hydrochloric acid, nitric acid, or sulfuric acid to activate the plating surface and washing again with water.
本発明の表面処理液を用いて浸漬処理した亜鉛系めっき鋼材は、その後、表面の余分な成分を取り除いて正常な皮膜を形成させるために、水洗した後、乾燥することが好ましい。この乾燥は、常温乾燥でも、加熱乾燥でもよい。 The galvanized steel material immersed using the surface treatment solution of the present invention is preferably washed with water and then dried in order to remove excess components on the surface and form a normal film. This drying may be room temperature drying or heat drying.
こうして、本発明により、亜鉛系めっき鋼材の表面に、３価クロム化合物を含有し、６価クロムを含まない処理液を用いて反応型浸漬処理により形成された黒色防錆皮膜を有する、黒色化亜鉛系めっき鋼材が提供される。この亜鉛系めっき表面に形成された黒色防錆皮膜は、当然、６価クロムを含まず、３価クロムを含む皮膜である。 Thus, according to the present invention, the surface of a zinc-based plated steel material has a black rust-proof coating formed by a reactive immersion treatment using a treatment solution containing a trivalent chromium compound and containing no hexavalent chromium. A galvanized steel material is provided. The black rust preventive film formed on the zinc-based plating surface is, of course, a film containing trivalent chromium without containing hexavalent chromium.
この黒色防錆皮膜がなぜ黒色を呈するかを、皮膜断面をオージェ分光分析装置により測定し、得られた結果を使って検討したところ、めっき表面との界面に亜鉛の低次酸化物を含んだ黒色層が生成しており、このめっき界面 (即ち、皮膜最下層) の黒色層のために、皮膜全体が黒色に見えるようになっていると結論づけられた。 The black rust-preventive film was measured for its black color by measuring the cross section of the film with an Auger spectrometer and examining the results using the results. It was concluded that a black layer had formed and that the entire coating appeared black because of the black layer at the plating interface (ie, the bottom layer of the coating).
周知のように、酸化亜鉛 (ZnＯ) は白色物質であり、活性な亜鉛系めっきの表面はすぐに酸化して、酸化亜鉛の白色を呈するようになる (白錆が発生する) 。しかし、本発明の表面処理液の場合、亜鉛めっき表面では、亜鉛が不完全にしか酸化されず、亜鉛の低次酸化物 (ZnＯx : ｘ＜0.8)の状態にとどまる。そして、この皮膜最下層に含まれる亜鉛の低次酸化物が黒色を呈するために、皮膜全体が黒く見えるのである。 As is well known, zinc oxide (ZnO) is a white substance, and the surface of an active zinc-based plating is immediately oxidized to become zinc oxide white (white rust is generated). However, in the case of the surface treatment solution of the present invention, zinc is only incompletely oxidized on the zinc plating surface, and remains in a state of a lower oxide of zinc (ZnO x : x <0.8). And, since the lower oxide of zinc contained in the lowermost layer of the film exhibits a black color, the entire film appears black.
この黒色の亜鉛低次酸化物がめっき表面に生成する理由は完全には解明されていないが、本発明の表面処理液が硝酸といった酸化剤を含有していないことと、コバルトイオンを含有することが関係していると考えられる。即ち、強力な酸化剤が存在していないため、酸性の表面処理液と接触して亜鉛が溶解して生じた亜鉛イオンが再び酸化物としてめっき表面で析出する際に、完全に酸化されずに、亜鉛の低次酸化物の状態でとどまると推測される。ZnＯx のｘが0.8 未満である亜鉛の低次酸化物は黒色となることは知られている。また、コバルトイオンは亜鉛の低次酸化物が生成する環境の創出に関与していると考えられる。コバルト以外の鉄系金属であるニッケルや鉄のイオンもいくらか有効であるが、コバルトイオンの効果が最も高い。それ以外に、リン酸と硫酸の比率やシュウ酸も皮膜の黒色化に関与しているが、その詳細は不明である。 The reason why this black zinc lower oxide is formed on the plating surface has not been completely elucidated, but the surface treatment solution of the present invention does not contain an oxidizing agent such as nitric acid and contains cobalt ions. Is considered to be related. That is, since there is no strong oxidizing agent, when the zinc ions produced by dissolving zinc in contact with the acidic surface treatment solution and precipitate again as oxides on the plating surface, they are not completely oxidized. It is speculated that they will remain in the state of a lower oxide of zinc. It is known that a lower oxide of zinc in which x of ZnO x is less than 0.8 turns black. Further, it is considered that cobalt ions are involved in creating an environment in which low-order oxides of zinc are generated. Nickel and iron ions, which are iron-based metals other than cobalt, are somewhat effective, but cobalt ions are the most effective. In addition, the ratio of phosphoric acid to sulfuric acid and oxalic acid also contribute to the blackening of the film, but the details are unknown.
めっき界面に形成された、亜鉛の低次酸化物を主成分とする最下層 (第１層) の黒色層の上には、オージェ分光分析の結果、第１層の上のクロムと亜鉛の不溶性リン酸塩を主成分とする層 (第２層) と、表層の亜鉛を含有しないのクロム／リンの酸化物層 (第３層) とが形成されていた。この３層構造からなる皮膜は、例えば、第１層が200 nm、第２層が500 nm、第３層が200 nmの厚みを有していて、第２層が最も厚く、第１層と第３層の厚みは比較的小さかった。この３層構造の皮膜では、第２層と第３層とで耐食性が確保され、特に第３層が亜鉛を含有していないため、高い耐食性を示すことができるものと推測される。 As a result of Auger spectroscopy, the insolubility of chromium and zinc on the first layer was found on the bottom black layer (first layer) mainly composed of a lower oxide of zinc formed at the plating interface. A layer mainly composed of phosphate (second layer) and a surface layer of zinc-free chromium / phosphorus oxide (third layer) were formed. The film having the three-layer structure has, for example, a first layer having a thickness of 200 nm, a second layer having a thickness of 500 nm, a third layer having a thickness of 200 nm, and a second layer having the largest thickness. The thickness of the third layer was relatively small. It is presumed that in the three-layered film, corrosion resistance is secured between the second layer and the third layer, and in particular, since the third layer does not contain zinc, it can exhibit high corrosion resistance.
但し、前述したように、皮膜を黒色化しているのは、めっき界面に形成された第１層に含まれる亜鉛の低次酸化物であり、この黒色層がめっき界面に形成されていれば、その上の層は、耐食性があれば、上記とは異なる層であってもよい。 However, as described above, the blackening of the film is due to the lower oxide of zinc contained in the first layer formed at the plating interface, and if this black layer is formed at the plating interface, The layer thereon may be a different layer as long as it has corrosion resistance.
この黒色防錆皮膜の全体の厚みは、特に制限されるものではないが、 300〜5000 nm の範囲であることが好ましい。300 nm以下では耐食性が不十分となる。5000 nm 以上の厚い皮膜を形成するには非常に長い処理時間が必要であって、コストが非常にかかる。 The total thickness of the black rust preventive film is not particularly limited, but is preferably in the range of 300 to 5000 nm. If it is less than 300 nm, the corrosion resistance becomes insufficient. Forming thick films of 5000 nm or more requires very long processing times and is very costly.
この黒色防錆皮膜の上に、耐食性をさらに高めるために、オーバーコート層を形成してもよい。このオーバーコート層は、クロメート皮膜や他の化成処理皮膜の上に従来より形成されているものであって、公知の方法や塗布液を使用して形成することができる。オーバーコート層は、その下の黒色防錆皮膜の色を損なわないように、透明のものとすることが好ましい。 An overcoat layer may be formed on the black rust preventive film in order to further increase the corrosion resistance. The overcoat layer is conventionally formed on a chromate film or another chemical conversion treatment film, and can be formed using a known method or a coating solution. The overcoat layer is preferably transparent so as not to impair the color of the underlying black rust preventive film.
具体的には、オーバーコート層は、コロイダルシリカ (ケイ酸ゾル) やチタニアゾルなどの金属酸化物（またはそれらの前駆物）またはリン酸塩を用いた無機質のものと、薄い樹脂被膜 (例、ポリエステル、アクリル樹脂、エポキシ樹脂、フェノール樹脂、ポリウレタン、メラミン樹脂、フッ素樹脂等) からなる有機質のものがあり、いずれを使用してもよい。その厚みについても特に制限はないが、通常は 0.1〜30μｍ程度である。オーバーコート層は、一般に処理液の塗布と乾燥により形成され、塗布は、鋼材の形状に応じて、浸漬、噴霧、ロール塗布など、適当な手段で実施すればよい。乾燥は普通には加熱乾燥である。 More specifically, the overcoat layer is made of a metal oxide (or a precursor thereof) such as colloidal silica (silicate sol) or titania sol or a phosphate, and a thin resin film (eg, polyester). , An acrylic resin, an epoxy resin, a phenol resin, a polyurethane, a melamine resin, a fluororesin, etc.), and any of them may be used. The thickness is not particularly limited, but is usually about 0.1 to 30 μm. The overcoat layer is generally formed by applying and drying a treatment liquid, and the application may be performed by an appropriate means such as dipping, spraying, or roll application according to the shape of the steel material. Drying is usually heat drying.
冷間圧延鋼板またはボルトに、市販の亜鉛または亜鉛−鉄合金めっき液を用いて電気亜鉛系めっき (膜厚８μｍ）を施した。電気亜鉛めっきは、鋼板にはジンケート浴を、ボルトには塩化浴を用いて行った。電気亜鉛−鉄合金めっきはジンケート浴を使用して行った。このめっき材（鋼板またはボルト）を、水洗した後、67.5％硝酸３ml/Lを含有する酸水溶液に室温で５秒間浸漬して活性化処理を行った。この活性化処理しためっき材を水洗してから、３価クロム化合物を含有し、６価クロムを含有しない、本発明の黒色防錆皮膜を形成するための表面処理液を用いて浸漬揺動処理を行い、最後に水洗した。使用した表面処理液の組成と処理条件 (浸漬処理時間と処理浴温) を表１に示す。 An electro-zinc plating (film thickness: 8 μm) was applied to a cold-rolled steel plate or bolt using a commercially available zinc or zinc-iron alloy plating solution. Electrogalvanizing was performed using a zincate bath for the steel sheet and a chloride bath for the bolts. Electric zinc-iron alloy plating was performed using a zincate bath. The plating material (steel plate or bolt) was washed with water, and then immersed in an aqueous acid solution containing 67.5% nitric acid (3 ml / L) at room temperature for 5 seconds to perform an activation treatment. After the activated plating material is washed with water, it is immersed and rocked using a surface treatment solution for forming a black rust-proof coating of the present invention containing a trivalent chromium compound and not containing hexavalent chromium. And finally washed with water. Table 1 shows the composition of the surface treatment solution used and the treatment conditions (immersion treatment time and treatment bath temperature).
本実施例では黒色防錆皮膜の上にオーバーコート層は形成しなかった。
比較例として、３価クロム化合物を含有し、６価クロム化合物を含有しないが、組成が本発明の範囲外である表面処理液を使用して黒色化処理を行った。具体的には、シュウ酸、リン酸、またはコバルト化合物のいずれかを含有しないか、またはリン酸イオン／硫酸イオンの質量比が１より小である表面処理液を使用した。処理液組成と処理条件を表２に示す。
In this example, no overcoat layer was formed on the black rust preventive film.
As a comparative example, a blackening treatment was performed using a surface treatment solution containing a trivalent chromium compound and not containing a hexavalent chromium compound but having a composition outside the scope of the present invention. Specifically, a surface treatment solution that did not contain any of oxalic acid, phosphoric acid, or a cobalt compound, or had a phosphate ion / sulfate ion mass ratio of less than 1 was used. Table 2 shows the composition of the processing solution and the processing conditions.
表１および表２において、「酸比」とは、リン酸イオン／硫酸イオンの質量比を意味する。硫酸イオンの量は、遊離の硫酸に加えて、コバルト化合物が硫酸コバルトである場合には、その硫酸イオンの量も含めた量である。 In Tables 1 and 2, “acid ratio” means the mass ratio of phosphate ion / sulfate ion. When the cobalt compound is cobalt sulfate in addition to free sulfuric acid, the amount of sulfate ion is the amount including the amount of sulfate ion.
また、従来例として、公知の亜鉛系めっき表面の黒色化用処理液を用いて黒色化処理を行った。その処理液の組成と処理条件は表３に示す。
上記のように表面処理した亜鉛系めっき材の外観（黒色度）と耐食性について、次のように評価した。それらの試験結果も、表１ (実施例) 、表２ (比較例) および表３ (従来例) に併記する。なお、亜鉛めっき材がボルトである場合、外観についてはボルト材により評価したが、明度と耐食性の評価は、鋼板に同じめっき浴とめっき条件で電気亜鉛系めっきおよび表面処理を行った試験片を用いて行った。
In addition, as a conventional example, a blackening treatment was performed using a known treatment liquid for blackening a zinc-based plating surface. Table 3 shows the composition of the processing solution and the processing conditions.
The appearance (blackness) and corrosion resistance of the zinc-based plated material surface-treated as described above were evaluated as follows. The test results are also shown in Table 1 (Example), Table 2 (Comparative Example) and Table 3 (Conventional Example). When the galvanized material is a bolt, the appearance was evaluated using the bolt material.Brightness and corrosion resistance were evaluated using a test piece that had been subjected to electro-zinc plating and surface treatment on the steel sheet in the same plating bath and plating conditions. It was carried out using.
外観：目視で次の基準で判定した。◎だけが良好な黒色皮膜である。
◎：黒色 (均一に真っ黒) 、
○：灰色 (一部が黒色だが不均一であるものを含む) 、
△：黒っぽい煤状物質が表面に付着している、
×：白色〜薄黄色。
Appearance: Visually evaluated according to the following criteria. Only ◎ is a good black film.
◎: Black (uniformly black),
○: Gray (including some black but non-uniform),
Δ: Black soot-like substance is attached to the surface,
X: White to pale yellow.
明度：東京電色社製のデジタルカラーメーターTC-3600 を用いて、Ｌ値 (Ｌ*ａ*ｂ* 表色系におけるＬ* 値) を測定し、次の基準で明度を評価した：
◎：Ｌ値＜15
○：15≦Ｌ値＜20
×：Ｌ値≧20。
Brightness: using Tokyo Denshoku made digital color meter TC-3600, measured L value (L * a * b * L * values in a color system) to evaluate the brightness by the following criteria:
◎: L value <15
：: 15 ≦ L value <20
×: L value ≧ 20.
耐食性：JIS Z 2371に準じた塩水噴霧試験（ＳＳＴ）を120 時間行い、試験後の白錆発生状況 (面積率) により、下記の基準で判定した。試験時間を120 時間としたのは、96〜120 時間の塩水噴霧試験で白錆が発生しないクロメート皮膜の耐食性と比較するためである。 Corrosion resistance: A salt spray test (SST) according to JIS Z 2371 was conducted for 120 hours, and the white rust occurrence state (area ratio) after the test was determined according to the following criteria. The test time was set to 120 hours in order to compare with the corrosion resistance of a chromate film that does not generate white rust in a salt spray test for 96 to 120 hours.
◎：120 時間で白錆発生なし、
○：120 時間での白錆発生面積率が10％未満、
×：120 時間での白錆発生面積率が10％以上。
◎: No white rust generated in 120 hours
：: The area ratio of white rust in 120 hours is less than 10%,
×: The area ratio of white rust in 120 hours is 10% or more.
表３に示すように、モリブデン酸塩や塩素酸塩を用いた従来例の黒色化処理では、Ｌ値が15未満で均一に真っ黒の黒色皮膜が形成された。しかし、その皮膜は、耐食性に著しく劣るものであった。 As shown in Table 3, in the conventional blackening process using molybdate or chlorate, an L value was less than 15, and a black black film was uniformly formed. However, the coating was extremely poor in corrosion resistance.
これに対し、表１に示すように、本発明の表面処理液を用いて黒色防錆皮膜を形成した実施例では、全例において、上記の従来例と同様に外観が完全に黒色 (即ち、均一に真っ黒) で、Ｌ値は15未満の高級感のある美しい黒色皮膜が形成された。より詳しくは、Ｌ値は12〜14の範囲であり、最大で13.8であった。しかも、この黒色皮膜はクロメート皮膜に匹敵する優れた耐食性も同時に示した。また、処理材の電気亜鉛めっき浴が塩化浴である場合にも、ジンケート浴の場合と全く同様の、Ｌ値が14以下の真っ黒の黒色防錆皮膜が形成され、めっき浴によって黒色防錆皮膜の着色に差が出ることがなかった。 In contrast, as shown in Table 1, in Examples in which a black rust-preventive film was formed using the surface treatment liquid of the present invention, the appearance was completely black (ie, A uniform black film having an L value of less than 15 was formed. More specifically, L values ranged from 12 to 14, with a maximum of 13.8. In addition, this black film also exhibited excellent corrosion resistance comparable to a chromate film. Also, when the electrogalvanizing bath of the treatment material is a chloride bath, a black black rust-preventive film having an L value of 14 or less is formed in exactly the same manner as in the zincate bath. There was no difference in coloring.
一方、表２に示すように、使用する表面処理液の組成が本発明の範囲外である比較例１〜８では、完全に黒色の外観が得られない上、耐食性も程度の差はあるが、低下する傾向があった。なお、これらの比較例の結果から、外観とＬ値がよく相関していることもわかる。 On the other hand, as shown in Table 2, in Comparative Examples 1 to 8 in which the composition of the surface treatment solution to be used is out of the range of the present invention, a completely black appearance is not obtained, and the corrosion resistance is also different. , Tended to decrease. The results of these comparative examples also show that the appearance and the L value are well correlated.
別の比較例として、前述した特許文献３ (特開2003−268562号公報) の実施例１〜６に従って亜鉛めっき鋼板の表面に黒色防錆皮膜を形成した。この実施例１〜６では、ジンケート浴を用いた電気亜鉛めっき鋼板を表面処理しているが、本実施例においては塩化浴とジンケート浴の両方の方法で電気亜鉛めっきを実施した。処理液の組成と処理条件 (温度、時間) は、この公報の表１に示されている組成および処理条件と同一であった。但し、シュウ酸を含有する処理液については、このシュウ酸が無水物であるか２水和物であるかが不明であったため、表示の濃度でシュウ酸無水物を使用した場合とシュウ酸２水和物を使用した場合の２種類の処理液を調製した。 As another comparative example, a black rust-proof coating was formed on the surface of a galvanized steel sheet according to Examples 1 to 6 of Patent Document 3 (Japanese Patent Application Laid-Open No. 2003-268562) described above. In Examples 1 to 6, an electrogalvanized steel sheet using a zincate bath was subjected to surface treatment. In this example, electrogalvanization was performed by both methods of a chloride bath and a zincate bath. The composition of the processing solution and the processing conditions (temperature and time) were the same as those shown in Table 1 of this publication. However, it was not known whether the oxalic acid was an anhydride or a dihydrate for the treatment solution containing oxalic acid. Two kinds of treatment liquids when hydrates were used were prepared.
形成された黒色防錆皮膜の外観と明度（Ｌ値）を上記と同様に評価した。その結果は下記の通りであった。
(1)この公報の実施例１〜６に従って、ジンケート浴で電気亜鉛めっきした亜鉛めっき鋼板を表面処理した場合、実施例４および６ではＬ値＝15の黒色皮膜が形成されたが、その他の実施例でのＬ値は、１例でＬ値が18であったのを除いて、Ｌ値は20以上であった (シュウ酸が無水物である場合と２水和物である場合の両方を含めて) 。
The appearance and lightness (L value) of the formed black rust preventive film were evaluated in the same manner as described above. The results were as follows.
(1) According to Examples 1 to 6 of this publication, when a galvanized steel sheet subjected to electrogalvanization in a zincate bath was subjected to a surface treatment, in Examples 4 and 6, a black film having an L value of 15 was formed. The L value in the examples was 20 or more except that the L value was 18 in one case (both when oxalic acid was an anhydride and when it was a dihydrate). Including).
(2)この公報の実施例１〜６の表面処理を、塩化浴で電気亜鉛めっきした亜鉛めっき鋼板に対して適用した場合、ジンケート浴の場合とは全く異なる結果が得られた。即ち、Ｌ値は最も低い場合でも22で、大半は30を超えるＬ値となった。Ｌ値が30を超えると、皮膜は淡い黄色であるか、またはそれが煤けたような色となり、灰色にもなっていなかった。 (2) When the surface treatments of Examples 1 to 6 of this publication were applied to a galvanized steel sheet electrogalvanized in a chloride bath, completely different results were obtained than in the zincate bath. That is, the L value was 22 even at the lowest, and most of the L values exceeded 30. Above an L value of 30, the film was pale yellow or it had a sooty color and was not gray.
これらの結果から、特許文献３に記載の表面処理液は、ジンケート浴による電気亜鉛系めっき鋼材については黒色防錆皮膜を形成できる場合もあるが、塩化浴で電気亜鉛めっきした亜鉛系めっき鋼材に対しては、黒色防錆皮膜を形成することができず、ジンケート浴と塩化浴とで、形成された皮膜に著しい差があることがわかる。即ち、この表面処理液は塩化浴を用いて電気亜鉛めっきを施した亜鉛めっき鋼材には適用しえないものである。 From these results, the surface treatment liquid described in Patent Literature 3 can form a black rust-proof coating on an electrogalvanized steel material in a zincate bath, but it is possible to form a galvanized steel material electrogalvanized in a chloride bath. On the other hand, it was not possible to form a black rust preventive film, and it was found that there was a remarkable difference in the film formed between the zincate bath and the chloride bath. That is, this surface treatment liquid cannot be applied to galvanized steel which is electrogalvanized using a chloride bath.
Claims (8)
The blackened zinc-based plated steel material according to claim 6 or 7, further comprising a colorless inorganic or organic overcoat layer on the black rust preventive film.
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