JP5929867B2 - Polyethylene coated steel pipe - Google Patents
Polyethylene coated steel pipe Download PDFInfo
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- JP5929867B2 JP5929867B2 JP2013208938A JP2013208938A JP5929867B2 JP 5929867 B2 JP5929867 B2 JP 5929867B2 JP 2013208938 A JP2013208938 A JP 2013208938A JP 2013208938 A JP2013208938 A JP 2013208938A JP 5929867 B2 JP5929867 B2 JP 5929867B2
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- 229910000831 Steel Inorganic materials 0.000 title claims description 89
- 239000010959 steel Substances 0.000 title claims description 89
- -1 Polyethylene Polymers 0.000 title claims description 44
- 239000004698 Polyethylene Substances 0.000 title claims description 22
- 229920000573 polyethylene Polymers 0.000 title claims description 22
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 94
- 239000002335 surface treatment layer Substances 0.000 claims description 57
- 239000010410 layer Substances 0.000 claims description 51
- 239000000377 silicon dioxide Substances 0.000 claims description 44
- 239000006087 Silane Coupling Agent Substances 0.000 claims description 40
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 36
- 239000011347 resin Substances 0.000 claims description 30
- 229920005989 resin Polymers 0.000 claims description 30
- ILRRQNADMUWWFW-UHFFFAOYSA-K aluminium phosphate Chemical compound O1[Al]2OP1(=O)O2 ILRRQNADMUWWFW-UHFFFAOYSA-K 0.000 claims description 29
- 239000012756 surface treatment agent Substances 0.000 claims description 29
- 229920013716 polyethylene resin Polymers 0.000 claims description 21
- BDSSZTXPZHIYHM-UHFFFAOYSA-N 2-phenoxypropanoyl chloride Chemical compound ClC(=O)C(C)OC1=CC=CC=C1 BDSSZTXPZHIYHM-UHFFFAOYSA-N 0.000 claims description 17
- UNTBPXHCXVWYOI-UHFFFAOYSA-O azanium;oxido(dioxo)vanadium Chemical compound [NH4+].[O-][V](=O)=O UNTBPXHCXVWYOI-UHFFFAOYSA-O 0.000 claims description 14
- 229910052845 zircon Inorganic materials 0.000 claims description 14
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 claims description 14
- 125000000524 functional group Chemical group 0.000 claims description 13
- 239000004593 Epoxy Substances 0.000 claims description 12
- 239000003795 chemical substances by application Substances 0.000 claims description 11
- 125000003700 epoxy group Chemical group 0.000 claims description 10
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 claims description 9
- 239000000853 adhesive Substances 0.000 claims description 9
- 230000001070 adhesive effect Effects 0.000 claims description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims description 5
- OTARVPUIYXHRRB-UHFFFAOYSA-N diethoxy-methyl-[3-(oxiran-2-ylmethoxy)propyl]silane Chemical compound CCO[Si](C)(OCC)CCCOCC1CO1 OTARVPUIYXHRRB-UHFFFAOYSA-N 0.000 claims description 5
- JXUKBNICSRJFAP-UHFFFAOYSA-N triethoxy-[3-(oxiran-2-ylmethoxy)propyl]silane Chemical compound CCO[Si](OCC)(OCC)CCCOCC1CO1 JXUKBNICSRJFAP-UHFFFAOYSA-N 0.000 claims description 5
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims description 3
- 229910000077 silane Inorganic materials 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 25
- 230000000694 effects Effects 0.000 description 23
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 22
- 239000000463 material Substances 0.000 description 22
- 239000002245 particle Substances 0.000 description 20
- 239000011247 coating layer Substances 0.000 description 17
- 238000000034 method Methods 0.000 description 15
- 230000007547 defect Effects 0.000 description 11
- 239000000243 solution Substances 0.000 description 11
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 8
- 238000000576 coating method Methods 0.000 description 8
- 239000011248 coating agent Substances 0.000 description 7
- 230000007797 corrosion Effects 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000012153 distilled water Substances 0.000 description 6
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 6
- 230000006872 improvement Effects 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 5
- 239000010936 titanium Substances 0.000 description 5
- 229910052719 titanium Inorganic materials 0.000 description 5
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000005507 spraying Methods 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- LLZRNZOLAXHGLL-UHFFFAOYSA-J titanic acid Chemical compound O[Ti](O)(O)O LLZRNZOLAXHGLL-UHFFFAOYSA-J 0.000 description 4
- 239000012808 vapor phase Substances 0.000 description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000000049 pigment Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 238000012935 Averaging Methods 0.000 description 2
- DBVJJBKOTRCVKF-UHFFFAOYSA-N Etidronic acid Chemical compound OP(=O)(O)C(O)(C)P(O)(O)=O DBVJJBKOTRCVKF-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 2
- 239000001506 calcium phosphate Substances 0.000 description 2
- 229910000389 calcium phosphate Inorganic materials 0.000 description 2
- 235000011010 calcium phosphates Nutrition 0.000 description 2
- 238000001723 curing Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000007865 diluting Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 238000007765 extrusion coating Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 239000003112 inhibitor Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- HJZKOAYDRQLPME-UHFFFAOYSA-N oxidronic acid Chemical compound OP(=O)(O)C(O)P(O)(O)=O HJZKOAYDRQLPME-UHFFFAOYSA-N 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 150000003009 phosphonic acids Chemical class 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 229920000098 polyolefin Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 125000005372 silanol group Chemical group 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 125000003396 thiol group Chemical group [H]S* 0.000 description 2
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- 239000012855 volatile organic compound Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- LRXTYHSAJDENHV-UHFFFAOYSA-H zinc phosphate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O LRXTYHSAJDENHV-UHFFFAOYSA-H 0.000 description 2
- 229910000165 zinc phosphate Inorganic materials 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 239000004606 Fillers/Extenders Substances 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 230000001680 brushing effect Effects 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 238000004210 cathodic protection Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000006482 condensation reaction Methods 0.000 description 1
- 238000007334 copolymerization reaction Methods 0.000 description 1
- 239000007822 coupling agent Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical class OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000010559 graft polymerization reaction Methods 0.000 description 1
- 238000013007 heat curing Methods 0.000 description 1
- 229920001903 high density polyethylene Polymers 0.000 description 1
- 239000004700 high-density polyethylene Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000000415 inactivating effect Effects 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 229960004592 isopropanol Drugs 0.000 description 1
- 239000004850 liquid epoxy resins (LERs) Substances 0.000 description 1
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- DCKVFVYPWDKYDN-UHFFFAOYSA-L oxygen(2-);titanium(4+);sulfate Chemical compound [O-2].[Ti+4].[O-]S([O-])(=O)=O DCKVFVYPWDKYDN-UHFFFAOYSA-L 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000003566 sealing material Substances 0.000 description 1
- 229920002379 silicone rubber Polymers 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 150000003609 titanium compounds Chemical class 0.000 description 1
- 229910000349 titanium oxysulfate Inorganic materials 0.000 description 1
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- BPSIOYPQMFLKFR-UHFFFAOYSA-N trimethoxy-[3-(oxiran-2-ylmethoxy)propyl]silane Chemical compound CO[Si](OC)(OC)CCCOCC1CO1 BPSIOYPQMFLKFR-UHFFFAOYSA-N 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Description
本発明は、鋼管表面に特定のノンクロメート系表面処理層を有するポリエチレン被覆鋼管に関する。 The present invention relates to a polyethylene-coated steel pipe having a specific non-chromate surface treatment layer on the surface of the steel pipe.
鋼管表面に防食層としてポリエチレン樹脂層を被覆した防食被覆鋼管は、防食性に優れていることから、ガス管、水道管、ケーブル保護管、ラインパイプなどの各種配管や鋼管杭などの土木用途などに広く利用されている。特に海底や地下への埋設用途が増大しており、その場合、電気防食が併用されることが多い。電気防食の効果によって鋼は防食されるが、一方で防食被覆が鋼界面から剥離しやすくなる問題があり、この問題は陰極剥離として知られている。 The anticorrosion coated steel pipe with a polyethylene resin layer coated on the surface of the steel pipe as an anticorrosion layer has excellent anticorrosion properties, so it can be used for various pipes such as gas pipes, water pipes, cable protection pipes, line pipes, and civil engineering applications such as steel pipe piles. Widely used. In particular, the use for embedding in the seabed or underground is increasing, and in that case, anticorrosion is often used in combination. Although the steel is anticorrosive due to the effect of cathodic protection, there is a problem that the anticorrosion coating tends to peel off from the steel interface, and this problem is known as cathodic peeling.
このような陰極剥離を抑制する方法として、クロメート処理が有効であることが知られている。例えば、特許文献１には、鋼材表面にクロメート層を有するクロメート被覆鋼材であって、エポキシプライマー層、無水マレイン酸変性ポリオレフィン層及びポリオレフィン層を順次積層した樹脂被覆重防食鋼材が開示されている。また、特許文献２には、鋼材の表面に特定のエポキシプライマーを適用するとともに、下地処理としてクロメート処理を施すことが示されている。 It is known that chromate treatment is effective as a method for suppressing such cathode peeling. For example, Patent Document 1 discloses a resin-coated heavy-duty anticorrosive steel material that is a chromate-coated steel material having a chromate layer on the surface of the steel material, in which an epoxy primer layer, a maleic anhydride-modified polyolefin layer, and a polyolefin layer are sequentially laminated. Patent Document 2 discloses that a specific epoxy primer is applied to the surface of a steel material and that chromate treatment is performed as a base treatment.
従来、クロメート処理は有機被覆材の下地処理として広く使用されてきたが、近年では環境上の懸念から使用が控えられている。このため最近では、クロメート処理を施さない、すなわち、ノンクロメート処理を施した耐食性に優れた有機被覆鋼材が望まれている。
また、特許文献３には、ノンクロメート処理を施した耐食性に優れた有機被覆鋼板が示されているが、めっき鋼板を処理して耐食性を向上させるものであり、鋼材表面に直接作用するものではなく、また、陰極剥離を抑制するものでもない。
Conventionally, chromate treatment has been widely used as a base treatment for organic coating materials, but in recent years it has been refrained from use due to environmental concerns. For this reason, recently, there is a demand for an organic coated steel material that is not subjected to chromate treatment, that is, is subjected to non-chromate treatment and has excellent corrosion resistance.
In addition, Patent Document 3 shows an organic coated steel sheet that has been subjected to non-chromate treatment and is excellent in corrosion resistance. However, it is intended to improve corrosion resistance by treating a plated steel sheet, and does not directly act on the steel surface. Neither does it suppress cathode peeling.
したがって本発明の目的は、以上のような従来技術の課題を解決し、樹脂被覆層の耐陰極剥離性に優れるとともに、クロメート処理を施すことなく製造することができるポリエチレン被覆鋼管を提供することにある。 Accordingly, an object of the present invention is to provide a polyethylene-coated steel pipe that solves the problems of the prior art as described above, is excellent in resistance to cathodic peeling of a resin coating layer, and can be manufactured without performing chromate treatment. is there.
本発明者らは、上記課題を解決すべく実験と検討を重ねた結果、以下のような知見を得た。
まず、本発明者らは、鋼材表面にシリカからなる表面処理層を形成することがポリエチレン被覆層の陰極剥離を防止するのに有効であることを見出した。しかしながら、シリカからなる表面処理層を効率良く鋼材表面に形成させることは、以下に述べるように困難を伴い、技術上の課題も多い。すなわち、シリカは鋼材との間では殆ど反応しないため、シリカを鋼材表面に処理層として形成させるためには、何らかのバインダー成分が必要である。そのため樹脂やクロメート液、若しくはチタン過酸化物などのような鋼材に付着する成分を必要とする。シリカは、それ自体である程度の防食性を有しているが、リン酸アルミニウムや炭酸ジルコニルアンモニウムなどのように鋼材表面を保護する機能を有しているものを加えた場合に、より性能の高い耐久性を有する。さらに、これらの機能を担う成分として、ジルコンフッ化アンモニウムやメタバナジン酸アンモニウムが挙げられる。しかしながら、これらから構成される表面処理層の上に有機被覆層を形成することを考えると、さらに表面処理層と有機被覆層、特に有機プライマー層との結合を強化させる成分を含有させることが、より高い耐久性をもたせるために必要となる。
As a result of repeated experiments and studies to solve the above problems, the present inventors have obtained the following knowledge.
First, the present inventors have found that forming a surface treatment layer made of silica on the surface of a steel material is effective in preventing cathode peeling of the polyethylene coating layer. However, it is difficult to form a surface treatment layer made of silica on the steel surface efficiently as described below, and there are many technical problems. That is, since silica hardly reacts with steel materials, some binder component is required to form silica as a treatment layer on the steel material surface. Therefore, a component adhering to the steel material such as resin, chromate liquid, or titanium peroxide is required. Silica has a certain degree of anticorrosion by itself, but it has higher performance when it has a function to protect the steel surface such as aluminum phosphate and zirconyl ammonium carbonate. It has durability. Furthermore, examples of the component responsible for these functions include ammonium zircon fluoride and ammonium metavanadate. However, considering the formation of the organic coating layer on the surface treatment layer composed of these, it is possible to further contain a component that strengthens the bonding between the surface treatment layer and the organic coating layer, particularly the organic primer layer, Necessary for higher durability.
そこで本発明者らは、シリカからなる表面処理層を鋼材表面に形成させる方法について鋭意検討し、その結果、以下のような知見を得た。表面処理層の主たる形成材として、シリカ（好ましくは気相法により製造されるシリカ。以下、「気相シリカ」という）とチタン過酸化物を用いる。チタン過酸化物の表面にはＯＨ基が存在するためシランカップリング剤と反応し結合を生成することができる。その結果、チタン過酸化物どうしの結合のほかに、シランカップリング剤を介してのチタン過酸化物どうしの結合生成も可能になる。また、シリカ（特に気相シリカ）の表面にはＯＨ基が多数存在し、このＯＨ基によりシランカップリング剤との反応が可能となる結果、シランカップリング剤を介してのシリカどうしの結合が生成する。また、鋼材表面にもＯＨ基が存在し、このＯＨ基もシランカップリング剤との反応が可能である。したがって、表面処理層を構成するに際してシランカップリング剤を用いることで、シランカップリング剤が、チタン過酸化物どうしの結合、シリカ粒子間の結合、鋼材とチタン過酸化物及びシリカの結合を可能にし、鋼材表面にシリカとチタン過酸化物を主体とする表面処理層を形成することが可能となる。そして、このような表面処理層を鋼材表面に形成することにより、ポリエチレン被覆層の耐陰極剥離性が効果的に高められる。また、シランカップリング剤は有機官能基と反応する部位を有し、それが表面処理層の上に形成されるプライマー層中の有機官能基と反応する結果、チタン過酸化物とシリカと有機プライマーとの結合に寄与し、表面処理層とその上層の有機プライマー層との接着が改善され、この点もポリエチレン被覆層の耐陰極剥離性の向上につながる。また、有機プライマー層としてはエポキシプライマーが好ましく、それとの接着性向上が期待でき、且つ良好な貯蔵安定性が得られるシランカップリング剤として、特に有機官能基としてエポキシ基を有するシランカップリング剤が好ましい。 Therefore, the present inventors diligently studied a method of forming a surface treatment layer made of silica on the steel material surface, and as a result, obtained the following knowledge. Silica (preferably silica produced by a vapor phase method, hereinafter referred to as “vapor phase silica”) and titanium peroxide are used as the main forming material of the surface treatment layer. Since an OH group exists on the surface of the titanium peroxide, it can react with the silane coupling agent to form a bond. As a result, in addition to bonding between titanium peroxides, bonding between titanium peroxides via a silane coupling agent can be generated. In addition, there are many OH groups on the surface of silica (particularly vapor phase silica), and this OH group enables reaction with the silane coupling agent. As a result, the silica is bonded to each other via the silane coupling agent. Generate. Moreover, OH group exists also on the steel material surface, and this OH group can react with a silane coupling agent. Therefore, by using a silane coupling agent when forming the surface treatment layer, the silane coupling agent can bond titanium peroxides, bond between silica particles, and bond steel materials with titanium peroxide and silica. Thus, a surface treatment layer mainly composed of silica and titanium peroxide can be formed on the steel material surface. And by forming such a surface treatment layer on the steel material surface, the cathode peel resistance of the polyethylene coating layer is effectively enhanced. In addition, the silane coupling agent has a site that reacts with an organic functional group, which reacts with the organic functional group in the primer layer formed on the surface treatment layer, resulting in titanium peroxide, silica, and an organic primer. The adhesion between the surface treatment layer and the upper organic primer layer is improved, and this also leads to the improvement of the cathode peel resistance of the polyethylene coating layer. Moreover, as an organic primer layer, an epoxy primer is preferable, and a silane coupling agent having an epoxy group as an organic functional group can be used as a silane coupling agent that can be expected to improve adhesion with the organic primer layer and obtain good storage stability. preferable.
そしてさらに、上記表面処理層中に、（i）適量のリン酸アルミニウム、炭酸ジルコニルアンモニウム、有機ホスホン酸化合物を複合添加することにより、鋼管表面の不働態化を促進させるという効果が得られ、（ii）好ましくはさらに、適量のジルコンフッ化アンモニウム、メタバナジン酸アンモニウムの１種以上を添加することにより、鋼管表面のｐＨ変化を抑制するという効果が得られ、これらにより、樹脂被覆層の耐陰極剥離性がさらに高められる。
以上の結果、クロメート処理材とほぼ同等の優れた耐陰極剥離性が得られる。
一方、上記表面処理層は、基本的に水分散性有機樹脂などの有機樹脂を含有しない方がよい。表面処理層が有機樹脂を含有すると、却って接着耐久性が低下しやすくなり、また、表面処理層を形成するための水性表面処理剤が増粘して塗装性が低下しやすくなるからである。また、接着耐久性が低下しやすくなる理由は、有機樹脂を含有すると塗装時に泡が発生しやすくなり、泡を含んだまま乾燥して脆弱な皮膜が形成されてしまうためであると考えられる。
Furthermore, in the surface treatment layer, (i) by adding a suitable amount of aluminum phosphate, zirconyl ammonium carbonate, and organic phosphonic acid compound, the effect of promoting passivation of the steel pipe surface can be obtained. ii) Preferably, the addition of an appropriate amount of one or more of ammonium zircon fluoride and ammonium metavanadate provides an effect of suppressing pH change on the surface of the steel pipe, and thereby the cathode peel resistance of the resin coating layer. Is further enhanced.
As a result of the above, excellent cathode peel resistance substantially equal to that of the chromate treatment material can be obtained.
On the other hand, the surface treatment layer should basically not contain an organic resin such as a water-dispersible organic resin. This is because if the surface treatment layer contains an organic resin, the adhesion durability tends to be lowered, and the aqueous surface treatment agent for forming the surface treatment layer is thickened and the paintability tends to be lowered. In addition, the reason why the adhesion durability is likely to be lowered is considered to be that when an organic resin is contained, bubbles are easily generated during coating, and a fragile film is formed by drying while containing the bubbles.
本発明はこのような知見に基づきなされたもので、以下を要旨とするものである。
［1］鋼管の表面に、シリカ（Ａ）、リン酸アルミニウム（Ｂ）、チタン過酸化物（Ｃ）、有機ホスホン酸化合物（Ｄ）、炭酸ジルコニルアンモニウム（Ｅ）及び有機官能基としてエポキシ基を有するシランカップリング剤（Ｈ）を含有し、該シランカップリング剤（Ｈ）は３−グリシドキシプロピルメチルジエトキシシラン、３−グリシドキシプロピルトリエトキシシランの中から選ばれる１種以上からなり、前記成分（Ａ），（Ｂ），（Ｃ），（Ｄ）及び（Ｅ）の合計１００質量部に対するシリカ（Ａ）の割合が４０〜５０質量部、リン酸アルミニウム（Ｂ）の割合が１０〜３０質量部、チタン過酸化物（Ｃ）の割合が５〜２０質量部、有機ホスホン酸化合物（Ｄ）の割合が６〜２４質量部、炭酸ジルコニルアンモニウム（Ｅ）の割合が２〜２０質量部、シランカップリング剤（Ｈ）の割合が５〜４０質量部である水性表面処理剤により形成された表面処理層を有し、
該表面処理層の上に、下層側から順に、エポキシ系プライマー樹脂層、接着性ポリエチレン樹脂層及びポリエチレン樹脂層を有すること特徴とするポリエチレン被覆鋼管。
The present invention has been made on the basis of such findings and has the following gist.
[1] Silica (A), aluminum phosphate (B), titanium peroxide (C), organic phosphonic acid compound (D), zirconyl ammonium carbonate (E) and an epoxy group as an organic functional group on the surface of the steel pipe A silane coupling agent (H) having at least one selected from 3-glycidoxypropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane. becomes, the proportion of the component (a), (B), (C), (D) and the ratio is 40 to 50 parts by weight of silica (a) to the total 100 parts by mass of (E), aluminum phosphate (B) Is 10-30 parts by mass, the ratio of titanium peroxide (C) is 5-20 parts by mass, the ratio of organic phosphonic acid compound (D) is 6-24 parts by mass, and the ratio of zirconyl ammonium carbonate (E) is 2. ~ 20 parts by mass, having a surface treatment layer formed by an aqueous surface treatment agent having a silane coupling agent (H) ratio of 5 to 40 parts by mass,
A polyethylene-coated steel pipe comprising an epoxy primer resin layer, an adhesive polyethylene resin layer, and a polyethylene resin layer in order from the lower layer side on the surface treatment layer.
［2］鋼管の表面に、シリカ（Ａ）、リン酸アルミニウム（Ｂ）、チタン過酸化物（Ｃ）、有機ホスホン酸化合物（Ｄ）、炭酸ジルコニルアンモニウム（Ｅ）及び有機官能基としてエポキシ基を有するシランカップリング剤（Ｈ）を含有し、該シランカップリング剤（Ｈ）は３−グリシドキシプロピルメチルジエトキシシラン、３−グリシドキシプロピルトリエトキシシランの中から選ばれる１種以上からなり、さらに、ジルコンフッ化アンモニウム（Ｆ）又は／及びメタバナジン酸アンモニウム（Ｇ）を含有し、前記成分（Ａ），（Ｂ），（Ｃ），（Ｄ），（Ｅ），（Ｆ）及び（Ｇ）の合計１００質量部に対するシリカ（Ａ）の割合が４０〜５０質量部、リン酸アルミニウム（Ｂ）の割合が１０〜３０質量部、チタン過酸化物（Ｃ）の割合が５〜２０質量部、有機ホスホン酸化合物（Ｄ）の割合が６〜２４質量部、炭酸ジルコニルアンモニウム（Ｅ）の割合が２〜２０質量部、ジルコンフッ化アンモニウム（Ｆ）の割合が２〜１５質量部、メタバナジン酸アンモニウム（Ｇ）の割合が２〜１０質量部、シランカップリング剤（Ｈ）の割合が５〜４０質量部である水性表面処理剤により形成された表面処理層を有し、
該表面処理層の上に、下層側から順に、エポキシプライマー樹脂層、接着性ポリエチレン樹脂層及びポリエチレン樹脂層を有すること特徴とするポリエチレン被覆鋼管。
[2] On the surface of the steel pipe, silica (A), aluminum phosphate (B), titanium peroxide (C), organic phosphonic acid compound (D), zirconyl ammonium carbonate (E) and an epoxy group as an organic functional group A silane coupling agent (H) having at least one selected from 3-glycidoxypropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane. And further containing ammonium zircon fluoride (F) and / or ammonium metavanadate (G), and the components (A), (B), (C), (D), (E), (F) and ( The proportion of silica (A) is 40 to 50 parts by mass, the proportion of aluminum phosphate (B) is 10 to 30 parts by mass, and the proportion of titanium peroxide (C) is 100 parts by mass of G). 5 to 20 parts by mass, 6 to 24 parts by mass of the organic phosphonic acid compound (D), 2 to 20 parts by mass of zirconyl ammonium carbonate (E), and 2 to 15 parts by mass of zircon ammonium fluoride (F) Part, the ratio of ammonium metavanadate (G) is 2 to 10 parts by mass, the ratio of the silane coupling agent (H) is 5 to 40 parts by mass, and has a surface treatment layer formed by an aqueous surface treatment agent,
A polyethylene-coated steel pipe having an epoxy primer resin layer, an adhesive polyethylene resin layer, and a polyethylene resin layer in order from the lower layer side on the surface treatment layer.
本発明のポリエチレン被覆鋼管は、電気防食が併用された場合において、樹脂被覆層の接着劣化による陰極剥離が効果的に抑制され、クロメート処理材とほぼ同等の優れた耐陰極剥離性が得られる。このように本発明のポリエチレン被覆鋼管は、クロメートを用いることなく優れた耐陰極剥離性を有するため、特に海底や地下への埋設用途に好適である。 In the polyethylene-coated steel pipe of the present invention, when the anticorrosion is used in combination, the cathode peeling due to the adhesion deterioration of the resin coating layer is effectively suppressed, and excellent cathode peeling resistance substantially equivalent to that of the chromate treatment material is obtained. Thus, since the polyethylene-coated steel pipe of the present invention has excellent cathode peeling resistance without using chromate, it is particularly suitable for embedment in the seabed or underground.
本発明のポリエチレン被覆鋼管は、鋼管表面に特定の水性表面処理剤（ノンクロメート系表面処理剤）により形成される表面処理層を有し、この表面処理層の上に複層の樹脂被覆層を有する。
まず、鋼管表面に形成される表面処理層について説明する。
この表面処理層は、シリカ（Ａ）、リン酸アルミニウム（Ｂ）、チタン過酸化物（Ｃ）、有機ホスホン酸化合物（Ｄ）、炭酸ジルコニルアンモニウム（Ｅ）及び有機官能基としてエポキシ基を有するシランカップリング剤（Ｈ）を含有し（好ましくは主成分として含有する）、さらに必要に応じてジルコンフッ化アンモニウム（Ｆ）又は／及びメタバナジン酸アンモニウム（Ｇ）を含有する（好ましくは主成分の一部として含有する）水性表面処理剤により形成される。
The polyethylene-coated steel pipe of the present invention has a surface treatment layer formed by a specific aqueous surface treatment agent (non-chromate surface treatment agent) on the surface of the steel pipe, and a multilayer resin coating layer is formed on the surface treatment layer. Have.
First, the surface treatment layer formed on the steel pipe surface will be described.
This surface treatment layer comprises silica (A), aluminum phosphate (B), titanium peroxide (C), organic phosphonic acid compound (D), zirconyl ammonium carbonate (E), and a silane having an epoxy group as an organic functional group. Contains a coupling agent (H) (preferably contained as a main component) and further contains ammonium zircon fluoride (F) and / or ammonium metavanadate (G) as necessary (preferably part of the main component) It is formed by an aqueous surface treating agent.
前記シリカ（Ａ）としては、その種類は特に問わないが、さきに述べた理由から気相シリカがより好ましい。
鋼管表面に形成される表面処理層は、シリカ粒子とチタン過酸化物によって形成されるネットワーク構造が主体になる。また、シリカ粒子の比表面積は、より緻密な構造を形成するという点から大きい方が有利である。比表面積は基本的に粒径に依存しており、粒径を小さくすることでより比表面積が大きくなり、緻密な構造を形成する上で有利になると考えられる。このような効果を得るためには、平均粒径が１０μｍ以下のシリカを使用することが好ましい。平均粒径が１０μｍを超えると、表面処理層に隙間構造が多くでき、表面処理層として欠陥の大きな層が形成されてしまう場合がある。また、このような観点から、より好ましくは、平均粒径が１０００ｎｍ以下の気相シリカを使用することが好ましい。なお、シリカ粒子は細かい方が分散性および接着耐久性の観点からは好ましいと考えられるため、平均粒径の下限は特に規定しない。
The type of silica (A) is not particularly limited, but gas phase silica is more preferable for the reason described above.
The surface treatment layer formed on the surface of the steel pipe is mainly composed of a network structure formed by silica particles and titanium peroxide. In addition, the larger specific surface area of the silica particles is advantageous from the viewpoint of forming a denser structure. The specific surface area basically depends on the particle diameter, and it is considered that the specific surface area is increased by reducing the particle diameter, which is advantageous in forming a dense structure. In order to obtain such an effect, it is preferable to use silica having an average particle size of 10 μm or less. When the average particle diameter exceeds 10 μm, a gap structure may be increased in the surface treatment layer, and a layer having a large defect may be formed as the surface treatment layer. From this point of view, it is more preferable to use vapor phase silica having an average particle size of 1000 nm or less. Since finer silica particles are considered preferable from the viewpoint of dispersibility and adhesion durability, the lower limit of the average particle size is not particularly specified.
なお、平均粒径については、シリカ粉少量を走査型電子顕微鏡（ＳＥＭ）で観察し、１０μｍ四方の視野を写真撮影し、はっきりと形状が確認できるシリカ粒子８個を無作為に選択（抽出）してそれらの粒径を測定する。これを５視野について行ない、全部で４０個のシリカ粒子の粒径を算術平均することにより、シリカの平均粒径を求める。 Regarding the average particle size, a small amount of silica powder is observed with a scanning electron microscope (SEM), a field of view of 10 μm square is photographed, and 8 silica particles whose shape can be clearly confirmed are randomly selected (extracted). Then, their particle size is measured. This is performed for five visual fields, and the average particle diameter of silica is obtained by arithmetically averaging the particle diameters of all 40 silica particles.
シリカ（Ａ）の割合は、成分（Ａ），（Ｂ），（Ｃ），（Ｄ）及び（Ｅ）の合計１００質量部、若しくは成分（Ｆ）又は／及び（Ｇ）が含まれる場合には成分（Ａ），（Ｂ），（Ｃ），（Ｄ），（Ｅ），（Ｆ）及び（Ｇ）の合計１００質量部（以下の各成分の配合割合の説明では、便宜上、上記を総称して「基本成分の合計１００質量部」という）に対して４０〜５０質量部、好ましくは４５〜５０質量部とする。この範囲でシリカ（Ａ）を含有させることで高い接着耐久性が得られる。シリカ（Ａ）の割合が４０質量部未満では、シリカ添加による効果が十分に得られない。一方、５０質量部を超えると、表面処理層に隙間構造が多くでき、表面処理層として欠陥の大きな層が形成されてしまうため耐陰極剥離性が低下する。 The proportion of silica (A) is 100 parts by mass in total of components (A), (B), (C), (D) and (E), or when component (F) or / and (G) is included. Is a total of 100 parts by mass of the components (A), (B), (C), (D), (E), (F) and (G). Collectively referred to as “total 100 parts by mass of basic components”) to 40-50 parts by mass, preferably 45-50 parts by mass. By including silica (A) within this range, high adhesion durability can be obtained. When the proportion of silica (A) is less than 40 parts by mass, the effect of silica addition cannot be sufficiently obtained. On the other hand, if it exceeds 50 parts by mass, the surface treatment layer can have a large number of gap structures, and a layer having a large defect is formed as the surface treatment layer, so that the cathode peel resistance is lowered.
前記リン酸アルミニウム（Ｂ）は、鋼材表面を保護する機能を有しており、含有することでより高い耐久性が得られ、耐陰極剥離性の向上に寄与する。リン酸アルミニウムは、平均粒径が５０μｍ以下のものが好ましく、特に１０μｍ以下のものが好ましい。ポリエチレン被覆鋼管が水に接するような環境におかれた場合、樹脂被覆層を透過した水により表面処理層中のリン酸アルミニウムが徐々に溶解し、鋼管表面まで到達するとリン酸アルミニウムにより鋼表面を不働態化する作用が発生する。この際、リン酸アルミニウムの平均粒径が５０μｍ以下であると、より溶解しやすくなり有利に働くことになる。なお、平均粒径については、リン酸アルミニウム粉少量を走査型電子顕微鏡（ＳＥＭ）で観察し、所定の視野を写真撮影し、はっきりと形状が確認できるリン酸アルミニウム粒子８個を無作為に選択（抽出）してそれらの粒径を測定する。これを５視野について行ない、全部で４０個のリン酸アルミニウム粒子の粒径を算術平均することにより、リン酸アルミニウムの平均粒径を求める。 The aluminum phosphate (B) has a function of protecting the surface of the steel material. By containing the aluminum phosphate (B), higher durability can be obtained, which contributes to improvement of the cathode peel resistance. The aluminum phosphate preferably has an average particle size of 50 μm or less, particularly preferably 10 μm or less. When the polyethylene-coated steel pipe is placed in contact with water, the aluminum phosphate in the surface treatment layer is gradually dissolved by the water that has permeated the resin coating layer. An inactivating effect occurs. At this time, if the average particle size of the aluminum phosphate is 50 μm or less, it becomes easier to dissolve and works advantageously. Regarding the average particle diameter, a small amount of aluminum phosphate powder is observed with a scanning electron microscope (SEM), a predetermined field of view is photographed, and 8 aluminum phosphate particles that can clearly confirm the shape are randomly selected. (Extract) and measure their particle size. This is performed for five visual fields, and the average particle diameter of the aluminum phosphate is determined by arithmetically averaging the particle diameters of all 40 aluminum phosphate particles.
リン酸アルミニウム（Ｂ）の割合は、基本成分の合計１００質量部に対して１０〜３０質量部、好ましくは１３〜２０質量部とする。リン酸アルミニウム（Ｂ）の割合が１０質量部未満では、リン酸アルミニウムの添加による効果が十分に得られないため耐陰極剥離性が劣り、一方、３０質量部を超えると、表面処理層に隙間構造が多くでき、表面処理層として欠陥の大きな層が形成されてしまうため耐陰極剥離性が低下する。
なお、リン酸アルミニウムと同様な効果を期待して、リン酸アルミニウムに代えてリン酸亜鉛やリン酸カルシウムを添加したが、リン酸アルミニウムと同様の効果は確認できなかった。
The proportion of aluminum phosphate (B) is 10 to 30 parts by mass, preferably 13 to 20 parts by mass with respect to 100 parts by mass of the total of the basic components. When the proportion of aluminum phosphate (B) is less than 10 parts by mass, the effect due to the addition of aluminum phosphate cannot be sufficiently obtained, so that the resistance to cathodic peeling is inferior. Since the structure can be increased and a layer having a large defect is formed as the surface treatment layer, the cathode peeling resistance is lowered.
In addition, in view of the same effect as aluminum phosphate, zinc phosphate or calcium phosphate was added instead of aluminum phosphate, but the same effect as aluminum phosphate could not be confirmed.
前記チタン過酸化物（Ｃ）は、シリカととともに、表面処理層の主体となるネットワーク構造を構成する。チタン過酸化物はそれ自体で緻密な皮膜を形成することが可能であるが、上記シリカと共存することで、緻密でかつ鋼管表面及び有機プライマー層との優れた密着性を示す表面処理層を形成することができる。また、シリカ（Ａ）を含有する表面処理層は上面が微細な凹凸面となるので、有機プライマー層のアンカー効果が発現し、これも密着性の向上に寄与する。 The titanium peroxide (C), together with silica, constitutes a network structure that is the main component of the surface treatment layer. Titanium peroxide can form a dense film by itself, but by coexisting with the silica, a surface treatment layer that is dense and exhibits excellent adhesion to the surface of the steel pipe and the organic primer layer. Can be formed. Moreover, since the upper surface of the surface treatment layer containing silica (A) is a fine uneven surface, the anchor effect of the organic primer layer is exhibited, which also contributes to the improvement of adhesion.
チタン過酸化物（Ｃ）は、チタン化合物を過酸化水素などの酸化剤で酸化することにより得ることができ、例えば、以下のような方法で得ることができる。
（1） 四塩化チタンに蒸留水を加えた溶液に、アンモニア水を滴下して水酸化チタンを沈殿させ、次いで、この沈殿した水酸化チタンを蒸留水で洗浄後、過酸化水素水溶液を加えて、チタン過酸化物を得る方法。具体的には、例えば、四塩化チタン６０質量％溶液を蒸留水で１００倍に希釈した溶液に、アンモニア水（１：９）を滴下し、水酸化チタンを沈殿させ、蒸留水で洗浄後、過酸化水素水３０質量％溶液を、初期の四塩化チタン６０質量％溶液の２倍量加えてかき混ぜ、チタンを含む黄色半透明の粘性のあるチタン過酸化物を得ることができる。
（2） テトラｉｓｏ−プロポキシチタンとｉｓｏ−プロパノールの混合物に、過酸化水素水と脱イオン水の混合物を滴下し、その後、時間をかけて熟成し、チタン過酸化物を得る方法。
The titanium peroxide (C) can be obtained by oxidizing a titanium compound with an oxidizing agent such as hydrogen peroxide, and can be obtained, for example, by the following method.
(1) Ammonia water is dropped into a solution obtained by adding distilled water to titanium tetrachloride to precipitate titanium hydroxide. Next, after washing the precipitated titanium hydroxide with distilled water, an aqueous hydrogen peroxide solution is added. To obtain titanium peroxide. Specifically, for example, ammonia water (1: 9) is dropped into a solution obtained by diluting a titanium tetrachloride 60% by mass solution with distilled water 100 times, to precipitate titanium hydroxide, and after washing with distilled water, A 30% by mass solution of hydrogen peroxide is added and stirred twice as much as the initial 60% by mass solution of titanium tetrachloride to obtain a yellow translucent viscous titanium peroxide containing titanium.
(2) A method in which a mixture of hydrogen peroxide and deionized water is dropped into a mixture of tetraiso-propoxytitanium and iso-propanol and then aged over time to obtain a titanium peroxide.
チタン過酸化物（Ｃ）の割合は、基本成分の合計１００質量部に対して５〜２０質量部、好ましくは８〜１６質量部とする。チタン過酸化物（Ｃ）の割合が５質量部未満では、チタン過酸化物の添加による効果が十分に得られないため耐陰極剥離性が劣り、一方、２０質量部を超えると耐水密着性が低下するため、耐陰極剥離性も低下する。 The ratio of the titanium peroxide (C) is 5 to 20 parts by mass, preferably 8 to 16 parts by mass with respect to 100 parts by mass of the total of the basic components. If the ratio of titanium peroxide (C) is less than 5 parts by mass, the effect of adding titanium peroxide cannot be sufficiently obtained, so that the cathode peel resistance is inferior. Therefore, the resistance to cathodic peeling is also reduced.
前記有機ホスホン酸化合物（Ｄ）は、表面処理剤、特にチタン過酸化物の貯蔵安定性を向上させるのに有効であり、その結果、耐陰極剥離性の向上にも寄与する。有機ホスホン酸化合物（Ｄ）としては、例えば、１−ヒドロキシエタン−１,１−ジホスホン酸、１−ヒドロキシメタン−１,１−ジホスホン酸などのヒドロキシル基含有有機ホスホン酸化合物；２−ヒドロキシホスホノ酢酸（カルボキシ（ヒドロキシ）メチルホスホン酸）などのカルボキシル基含有有機ホスホン酸化合物；及びこれらの塩などが挙げられ、これらの１種以上を用いることができる。
有機ホスホン酸化合物（Ｄ）の割合は、基本成分の合計１００質量部に対して６〜２４質量部、好ましくは７〜２３質量部とする。また、チタン過酸化物（Ｃ）の配合量に対して質量比で１．２〜１．５倍とすることが好ましい。有機ホスホン酸化合物（Ｄ）の割合が６質量部未満では、有機ホスホン酸化合物の添加による効果が十分に得られないため耐陰極剥離性が劣り、一方、２４質量部を超えると耐水密着性が劣化するため、耐陰極剥離性も低下する。
The organic phosphonic acid compound (D) is effective in improving the storage stability of the surface treatment agent, particularly titanium peroxide, and as a result, contributes to the improvement in resistance to cathodic peeling. Examples of the organic phosphonic acid compound (D) include hydroxyl group-containing organic phosphonic acid compounds such as 1-hydroxyethane-1,1-diphosphonic acid and 1-hydroxymethane-1,1-diphosphonic acid; Examples thereof include carboxyl group-containing organic phosphonic acid compounds such as acetic acid (carboxy (hydroxy) methylphosphonic acid); and salts thereof, and one or more of these can be used.
The ratio of the organic phosphonic acid compound (D) is 6 to 24 parts by mass, preferably 7 to 23 parts by mass with respect to 100 parts by mass of the total of the basic components. Moreover, it is preferable to set it as 1.2 to 1.5 times by mass ratio with respect to the compounding quantity of a titanium peroxide (C). If the proportion of the organic phosphonic acid compound (D) is less than 6 parts by mass, the effect of addition of the organic phosphonic acid compound cannot be sufficiently obtained, so that the cathode peel resistance is inferior. Since it deteriorates, the cathode peel resistance also decreases.
前記炭酸ジルコニルアンモニウム（Ｅ）は、鋼管表面を不働態化させる作用とインヒビターとしての作用を有し、鋼管表面の耐食性を向上させる結果、上記したような鋼管の腐食反応に伴う鋼表面の環境(ｐＨ)の変化を抑制し、樹脂被覆層の剥離や接着劣化を引き起こしにくくする表面処理層が形成される。その結果、耐陰極剥離性の向上に寄与する。
炭酸ジルコニルアンモニウム（Ｅ）の割合は、基本成分の合計１００質量部に対して２〜２０質量部、好ましくは３〜１０質量部とする。この範囲で含有することで、樹脂被覆層の高い接着耐久性が得られる。炭酸ジルコニルアンモニウム（Ｅ）の割合が２質量部未満では、炭酸ジルコニルアンモニウムの添加による効果が十分に得られないため耐陰極剥離性が劣り、一方、２０質量部を超えると耐水密着性が劣化するため、耐陰極剥離性も低下する。
The zirconyl ammonium carbonate (E) has an action to passivate the surface of the steel pipe and an action as an inhibitor, and as a result of improving the corrosion resistance of the surface of the steel pipe, the environment of the steel surface accompanying the corrosion reaction of the steel pipe as described above ( A surface treatment layer is formed that suppresses changes in pH and makes it difficult to cause the resin coating layer to peel off or to deteriorate the adhesion. As a result, it contributes to improvement of the resistance to cathode peeling.
The ratio of zirconyl ammonium carbonate (E) is 2 to 20 parts by mass, preferably 3 to 10 parts by mass with respect to 100 parts by mass as the total of the basic components. By containing in this range, high adhesion durability of the resin coating layer can be obtained. If the proportion of zirconyl ammonium carbonate (E) is less than 2 parts by mass, the effect of adding zirconyl ammonium carbonate cannot be sufficiently obtained, so that the cathode peel resistance is inferior. On the other hand, if it exceeds 20 parts by mass, the water-resistant adhesion deteriorates. For this reason, the cathode peel resistance is also lowered.
ジルコンフッ化アンモニウム（Ｆ）、メタバナジン酸アンモニウム（Ｇ）も、鋼管表面を不働態化させる作用とインヒビターとしての作用を有し、鋼管表面の耐食性を向上させる結果、上記した鋼管の腐食反応に伴う鋼表面の環境(ｐＨ)の変化を抑制し、有機被覆層の剥離や接着劣化を引き起こしにくくする表面処理層の形成に寄与する。したがって、表面処理剤にさらに、ジルコンフッ化アンモニウム（Ｆ）、メタバナジン酸アンモニウム（Ｇ）の１種以上を加えることにより、一段と高い接着耐久性が得られ、その結果、耐陰極剥離性がより向上する。 Zircon ammonium fluoride (F) and ammonium metavanadate (G) also have the effect of passivating the steel pipe surface and acting as an inhibitor, and as a result of improving the corrosion resistance of the steel pipe surface, the steel accompanying the corrosion reaction of the steel pipe described above It contributes to the formation of a surface treatment layer that suppresses changes in the surface environment (pH) and makes it difficult to cause peeling or adhesion deterioration of the organic coating layer. Therefore, by further adding at least one of zircon ammonium fluoride (F) and ammonium metavanadate (G) to the surface treatment agent, higher adhesion durability can be obtained, and as a result, the cathode peel resistance is further improved. .
ジルコンフッ化アンモニウム（Ｆ）は基本成分の合計１００質量部に対して２〜１５質量部（好ましくは４〜１３質量部）、メタバナジン酸アンモニウム（Ｇ）は基本成分の合計１００質量部に対して２〜１０質量部（好ましくは３〜６質量部）、それぞれ配合することにより効果が発揮される。すなわち、ジルコンフッ化アンモニウム（Ｆ）、メタバナジン酸アンモニウム（Ｇ）の割合がそれぞれ２質量部未満では、これらの成分添加による効果が十分に得られず、一方、ジルコンフッ化アンモニウム（Ｆ）の割合が１５質量部を、また、メタバナジン酸アンモニウム（Ｇ）の割合が１０質量部を、それぞれ超えても耐陰極剥離性のさらなる向上効果は期待できない。 Zircon ammonium fluoride (F) is 2 to 15 parts by mass (preferably 4 to 13 parts by mass) with respect to 100 parts by mass of the basic components, and ammonium metavanadate (G) is 2 with respect to 100 parts by mass of the basic components. -10 mass parts (preferably 3-6 mass parts) and an effect are exhibited by mix | blending each. That is, when the proportions of zircon ammonium fluoride (F) and ammonium metavanadate (G) are each less than 2 parts by mass, the effect of adding these components cannot be sufficiently obtained, while the proportion of zircon ammonium fluoride (F) is 15 Even if the mass part and the proportion of ammonium metavanadate (G) exceed 10 parts by mass, no further improvement effect of the cathode peel resistance can be expected.
前記シランカップリング剤（Ｈ）（有機官能基としてエポキシ基を有するシランカップリング剤）は、上記のようにチタン過酸化物とシリカの結合、さらに、それらと有機プライマー層及び鋼管表面との結合に寄与する。シランカップリング剤は各種のものが知られているが、その大半がシラノール基と有機官能基を有するものである。有機官能基としては、表面処理層の上に形成される有機プライマー層に使用されるエポキシ系樹脂と反応性に優れている点から、エポキシ基またはメルカプト基が好適であるが、メルカプト基を有するシランカップリング剤を用いると貯蔵安定性が悪い。このため本発明では、有機官能基としてエポキシ基を有するシランカップリング剤（Ｈ）を用いる。 The silane coupling agent (H) (a silane coupling agent having an epoxy group as an organic functional group) is bonded to titanium peroxide and silica as described above, and further bonded to the organic primer layer and the steel pipe surface. Contribute to. Various types of silane coupling agents are known, but most of them have silanol groups and organic functional groups. As the organic functional group, an epoxy group or a mercapto group is preferable because it has excellent reactivity with the epoxy resin used for the organic primer layer formed on the surface treatment layer, but has a mercapto group. When a silane coupling agent is used, the storage stability is poor. For this reason, in this invention, the silane coupling agent (H) which has an epoxy group as an organic functional group is used.
有機官能基としてエポキシ基を有するシランカップリング剤（Ｈ）としては、例えば、３−グリシドキシプロピルトリメトキシシラン、３−グリシドキシプロピルメチルジエトキシシラン、３−グリシドキシプロピルトリエトキシシランなどが挙げられ、これらの１種以上を用いることができる。これらのシランカップリング剤は、いずれもシラノール基を複数有するので、チタン過酸化物とシリカ間、或いはそれらと鋼管表面間、有機プライマー層間に架橋構造が形成され、チタン過酸化物及びシリカの鋼管表面上での固定、及び有機プライマー層との間での接着の効果が期待できる。 Examples of the silane coupling agent (H) having an epoxy group as an organic functional group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane. One or more of these can be used. Since each of these silane coupling agents has a plurality of silanol groups, a crosslinked structure is formed between the titanium peroxide and silica, or between them and the steel pipe surface, and between the organic primer layers, and the titanium peroxide and silica steel pipe. The effect of fixing on the surface and adhesion between the organic primer layer can be expected.
シランカップリング剤（Ｈ）の割合は、基本成分の合計１００質量部に対して５〜４０質量部、好ましくは１５〜２５質量部とする。シランカップリング剤（Ｈ）の割合が５質量部未満では上記のような種々の結合効果が発現しないため耐陰極剥離性が劣り、一方、４０質量部を超えると多数のシランカップリング剤どうしが自己縮合反応するため、上記のチタン過酸化物及びシリカとの結合が却って弱くなるなどの弊害をきたすため、却って耐陰極剥離性が低下する。また、処理剤の安定性が損なわれるなどの悪影響もある。 The ratio of the silane coupling agent (H) is 5 to 40 parts by mass, preferably 15 to 25 parts by mass with respect to 100 parts by mass as the total of the basic components. When the proportion of the silane coupling agent (H) is less than 5 parts by mass, the various bonding effects as described above are not exhibited, so that the resistance to cathodic peeling is poor. On the other hand, when the proportion exceeds 40 parts by mass, a large number of silane coupling agents are present. Since the self-condensation reaction causes adverse effects such as weakening of the bond between the titanium peroxide and silica, the cathode peel resistance is deteriorated. In addition, there are adverse effects such as the stability of the treatment agent being impaired.
また、水性表面処理剤には、本発明の効果を妨げない限度で、他の成分、例えば、顔料などの添加成分を適量配合することを妨げない。ただし、水性表面処理剤には、基本的に水分散性有機樹脂などの有機樹脂は配合しない方がよい。有機樹脂を配合すると、却って接着耐久性が低下しやすくなり、また、水性表面処理剤が増粘して塗装性が低下しやすくなり、この傾向は配合量が多くなるほど顕著になる。このため、有機樹脂を配合する場合でも基本成分の合計１００質量部に対して２質量部以下が好ましく、添加しないことが特に望ましい。 Further, the aqueous surface treating agent does not prevent the addition of an appropriate amount of other components, for example, an additive component such as a pigment, as long as the effects of the present invention are not hindered. However, it is better not to mix an organic resin such as a water-dispersible organic resin with the aqueous surface treatment agent. When an organic resin is blended, the adhesion durability tends to decrease, and the aqueous surface treatment agent tends to thicken and the paintability tends to decrease. This tendency becomes more prominent as the blending amount increases. For this reason, even when blending an organic resin, 2 parts by mass or less is preferable with respect to a total of 100 parts by mass of the basic components, and it is particularly desirable not to add them.
表面処理層の付着量は、上記成分（Ａ）〜（Ｈ）の合計で０.１ｇ／ｍ２以上が好ましく、また、より好ましくは０.８〜１０ｇ／ｍ２、特に好ましくは１〜８ｇ／ｍ２である。表面処理層の付着量が０.１ｇ／ｍ２未満では、表面処理層による効果が低下し、一方、付着量が過剰になると、経済的に不利となるばかりでなく、却って耐陰極剥離性が低下するようになる。 The total amount of the components (A) to (H) is preferably 0.1 g / m 2 or more, more preferably 0.8 to 10 g / m 2 , and particularly preferably 1 to 8 g. / M 2 . When the adhesion amount of the surface treatment layer is less than 0.1 g / m 2 , the effect of the surface treatment layer is reduced. On the other hand, when the adhesion amount is excessive, it is not only economically disadvantageous, but also has a resistance to cathode peeling. It begins to decline.
本発明において、表面処理層を形成するための表面処理剤は、上述した各成分を水に溶解又は分散させた水性表面処理剤である。溶媒を水としたのは、処理時における環境上の問題を考慮したためである。有機溶媒でも表面処理は可能であるが、処理時に蒸発させて溶媒を取り除くので、有機溶媒では揮発性有機化合物（ＶＯＣ）などの有害物質の発生が懸念される。
表面処理剤の粘度・塗装性などを考慮して、水の量は基本成分１００質量部に対して９００〜５０００質量部が好ましく、１５００〜２５００質量部がさらに好ましい。それ以上希釈すると、スプレー、はけ塗り、転写などの通常の塗装方法では、鋼管表面に塗布する際に十分な塗布量（付着量）が確保できない場合がある。また、シランカップリング剤（Ｈ）は、水と成分（Ａ）〜（Ｇ）の合計質量に対し２.０質量％を超えて添加すると凝集する恐れがあるため、シランカップリング剤量が水と成分（Ａ）〜（Ｇ）の合計質量に対して２.０質量％以下となるように、水の量を調整することが好ましい。
In the present invention, the surface treatment agent for forming the surface treatment layer is an aqueous surface treatment agent in which the above-described components are dissolved or dispersed in water. The reason why the solvent is water is that environmental problems during processing are taken into consideration. Surface treatment is possible with an organic solvent, but since the solvent is removed by evaporation during the treatment, there is a concern that harmful substances such as volatile organic compounds (VOC) may be generated in the organic solvent.
Considering the viscosity and paintability of the surface treatment agent, the amount of water is preferably 900 to 5000 parts by mass, more preferably 1500 to 2500 parts by mass with respect to 100 parts by mass of the basic component. If it is further diluted, a normal coating method such as spraying, brushing, or transfer may not ensure a sufficient coating amount (adhesion amount) when coating on the surface of the steel pipe. Moreover, since the silane coupling agent (H) may aggregate when added in excess of 2.0 mass% with respect to the total mass of water and the components (A) to (G), the amount of the silane coupling agent is water. It is preferable to adjust the amount of water so that it is 2.0 mass% or less with respect to the total mass of the components (A) to (G).
また、本発明で使用する表面処理剤を調製するにあたり、調製後使用するまでの時間が長期化する場合、シランカップリング剤の安定性が問題となる場合がある。これは、シランカップリング剤を一度混合すると水溶液中でシランカップリング剤どうしが反応して自己縮合し、シランカップリング剤が機能しなくなることがあるためである。そのため、シランカップリング剤（Ｈ）以外の成分（Ａ）〜（Ｇ）を調合したものに、シランカップリング剤（Ｈ）を添加した後は、鋼管への接触処理まで、あまり長期間おかない方が好ましい。また、シランカップリング剤（Ｈ）を添加した後には、各成分の分散を良好にするという意味で１時間程度の撹拌を行うのが好ましい。 Moreover, when preparing the surface treating agent used by this invention, when the time until it uses it after preparation prolongs, stability of a silane coupling agent may become a problem. This is because once the silane coupling agent is mixed, the silane coupling agents react with each other in the aqueous solution and self-condensate, and the silane coupling agent may not function. Therefore, after adding the silane coupling agent (H) to the mixture of the components (A) to (G) other than the silane coupling agent (H), the contact treatment to the steel pipe does not take a long time. Is preferred. Moreover, after adding a silane coupling agent (H), it is preferable to stir about 1 hour in the meaning of making dispersion | distribution of each component favorable.
表面処理剤の調製と、この表面処理剤による鋼管表面への表面処理層の形成は、例えば、以下の方法で行うことができる。
所定量のシリカ（Ａ）、リン酸アルミニウム（Ｂ）、チタン過酸化物（Ｃ）、有機ホスホン酸化合物（Ｄ）、炭酸ジルコニルアンモニウム（Ｅ）、さらに必要に応じてジルコンフッ化アンモニウム（Ｆ）又は／及びメタバナジン酸アンモニウム（Ｇ）を水に溶解又は分散させ、これにシランカップリング剤（Ｈ）を所定量加えて１０〜６０分ほど撹拌し、各成分を十分に溶解又は分散させた表面処理剤を調製する。この表面処理剤中には、他のシランカップリング剤や、添加成分の安定性をコントロールするための酸や安定剤、沈降防止剤などを添加してもよい。以上により得られた表面処理剤を鋼管表面に接触させる。接触させる方法としては、スプレー塗布法、鋼管表面に適量を滴下してシリコンゴム等でしごく方法、など任意の方法でよい。その後、６０〜１００℃程度に加熱するなどの方法で水を蒸発させ、これにより鋼管表面に表面処理層が形成される。
The preparation of the surface treatment agent and the formation of the surface treatment layer on the steel pipe surface by this surface treatment agent can be performed, for example, by the following method.
A predetermined amount of silica (A), aluminum phosphate (B), titanium peroxide (C), organic phosphonic acid compound (D), zirconyl ammonium carbonate (E), and if necessary, zircon ammonium fluoride (F) or / And surface treatment in which ammonium metavanadate (G) is dissolved or dispersed in water, a predetermined amount of silane coupling agent (H) is added thereto and stirred for about 10 to 60 minutes, and each component is sufficiently dissolved or dispersed Prepare the agent. In the surface treatment agent, other silane coupling agents, acids and stabilizers for controlling the stability of the added components, anti-settling agents, and the like may be added. The surface treating agent obtained by the above is made to contact the steel pipe surface. The contacting method may be any method such as a spray coating method, a method in which an appropriate amount is dropped onto the surface of a steel pipe and then rubbed with silicon rubber or the like. Thereafter, water is evaporated by a method such as heating to about 60 to 100 ° C., whereby a surface treatment layer is formed on the surface of the steel pipe.
次に、上記表面処理層の上に形成される複層の樹脂被覆層について説明する。
上述した表面処理層の上には、下層側から順に、エポキシ系プライマー樹脂層、接着性ポリエチレン樹脂層及びポリエチレン樹脂層が形成される。
エポキシ系プライマーとしては、例えば、ビスフェノールＡ型のエポキシ樹脂にアミン系硬化剤を混合し、必要に応じて体質顔料や防錆顔料を添加したものを用いることができ、このようなエポキシ系プライマーを硬化させてエポキシ系プライマー樹脂層を形成させることができる。接着性ポリエチレン樹脂層を形成する接着性ポリエチレン樹脂としては、例えば、ポリエチレン樹脂に無水マレイン酸を共重合またはグラフト重合させたものを用いることができる。また、ポリエチレン樹脂層を形成するポリエチレン樹脂としては、低密度、中密度、高密度のいずれのポリエチレン樹脂を用いてもよいが、特に高密度ポリエチレン樹脂が望ましい。
Next, the multilayer resin coating layer formed on the surface treatment layer will be described.
On the surface treatment layer described above, an epoxy primer resin layer, an adhesive polyethylene resin layer, and a polyethylene resin layer are formed in order from the lower layer side.
As the epoxy primer, for example, a bisphenol A type epoxy resin mixed with an amine curing agent, and an extender pigment or a rust preventive pigment added as necessary can be used. It can be cured to form an epoxy-based primer resin layer. As the adhesive polyethylene resin for forming the adhesive polyethylene resin layer, for example, a polyethylene resin obtained by copolymerization or graft polymerization of maleic anhydride can be used. Moreover, as a polyethylene resin which forms a polyethylene resin layer, you may use any polyethylene resin of a low density, a medium density, and a high density, However, A high density polyethylene resin is especially desirable.
各樹脂層の形成方法は、従来公知の方法でよく、例えば、エポキシ系プライマーを表面処理層の上にスプレー塗布し、加熱硬化させた後、接着性ポリエチレン樹脂とポリエチレン樹脂を押出被覆で被覆するなどの方法を採ることができる。
表面処理層と樹脂層は、鋼管内外面の任意の面に形成することができるが、通常は鋼管外面のみに形成される。
有機プライマー層下の界面を破壊する主たる作用としては、有機プライマー層を透過する酸素及び水などが引き起こす陰極反応の結果として生成するアルカリなどによる界面の破壊が挙げられる。これに対して、本発明のポリエチレン被覆鋼管では、表面処理剤により形成される表面処理層が、リン酸やクロメート処理層とは異なり、基本的にアルカリに不溶性であるので、有機プライマー層下の接着耐久性が向上し、耐陰極剥離性が向上するものと考えられる。
The method for forming each resin layer may be a conventionally known method. For example, after spray-coating an epoxy-based primer on the surface treatment layer and heat-curing, the adhesive polyethylene resin and the polyethylene resin are covered by extrusion coating. It is possible to adopt such a method.
The surface treatment layer and the resin layer can be formed on any surface on the inner and outer surfaces of the steel pipe, but are usually formed only on the outer surface of the steel pipe.
The main effect of destroying the interface under the organic primer layer is the destruction of the interface due to alkali or the like generated as a result of the cathode reaction caused by oxygen and water permeating the organic primer layer. On the other hand, in the polyethylene-coated steel pipe of the present invention, the surface treatment layer formed by the surface treatment agent is basically insoluble in alkali unlike the phosphoric acid or chromate treatment layer. It is considered that the adhesion durability is improved and the cathode peeling resistance is improved.
［表面処理剤の調製］
鋼管表面に塗布する表面処理剤は、以下のようにして調製した。
イオン交換水中にシリカ（平均粒径９００ｎｍの気相シリカ）を添加し、撹拌して分散させた後、リン酸アルミニウム（平均粒径８μｍ、１５μｍ、５０μｍ）、チタン過酸化物、有機ホスホン酸化合物（１−ヒドロキシエタン−１，１−ジホスホン酸または１−ヒドロキシメタン−１，１−ジホスホン酸）、炭酸ジルコニルアンモニウム、ジルコンフッ化アンモニウム、メタバナジン酸アンモニウムを適宜添加した。次いで、シランカップリング剤を添加して６０分間撹拌し、表面処理剤を調製した。なお、実施例No.９４の表面処理剤には、さらに水分散性アクリル樹脂を添加した。
[Preparation of surface treatment agent]
The surface treatment agent applied to the steel pipe surface was prepared as follows.
Silica (gas phase silica having an average particle size of 900 nm) is added to ion-exchanged water and dispersed by stirring, and then aluminum phosphate (average particle size: 8 μm, 15 μm, 50 μm), titanium peroxide, organic phosphonic acid compound (1-hydroxyethane-1,1-diphosphonic acid or 1-hydroxymethane-1,1-diphosphonic acid), zirconyl ammonium carbonate, zircon ammonium fluoride, and ammonium metavanadate were appropriately added. Next, a silane coupling agent was added and stirred for 60 minutes to prepare a surface treatment agent. In addition, a water dispersible acrylic resin was further added to the surface treatment agent of Example No. 94.
また、比較のために、リン酸アルミニウムに代えてリン酸亜鉛またはリン酸カルシウムを添加した表面処理剤、チタン過酸化物に代えてチタンのオキシ硫酸塩である硫化チタニルを添加した表面処理剤をそれぞれ調製した。
前記チタン過酸化物は、以下のようにして得られたものである。すなわち、四塩化チタン６０質量％溶液を蒸留水で１００倍に希釈した溶液に、アンモニア水（１：９）を滴下し、水酸化チタンを沈殿させ、蒸留水で洗浄後、過酸化水素水３０質量％溶液を、初期の四塩化チタン６０質量％溶液の２倍量加えてかき混ぜ、チタンを含む黄色半透明の粘性のあるチタン過酸化物を得た。
表面処理剤中での各成分及び水の配合量を表１〜表１０に示す。
For comparison, a surface treatment agent added with zinc phosphate or calcium phosphate instead of aluminum phosphate, and a surface treatment agent added with titanyl sulfide, which is a titanium oxysulfate, instead of titanium peroxide, were prepared. did.
The titanium peroxide is obtained as follows. That is, ammonia water (1: 9) was dropped into a solution obtained by diluting a titanium tetrachloride 60 mass% solution 100 times with distilled water to precipitate titanium hydroxide, washed with distilled water, hydrogen peroxide solution 30 The mass% solution was added and stirred twice as much as the initial 60 mass% titanium tetrachloride solution to obtain a yellow translucent viscous titanium peroxide containing titanium.
Tables 1 to 10 show the amount of each component and water in the surface treatment agent.
［ポリエチレン被覆鋼管の作製］
鋼管は、ＪＩＳ ＳＧＰ
８０Ａサイズとし、黒皮をブラスト処理で取り除いたものを使用した。この鋼管の外面に表面処理剤を一定量スプレー塗布した後、誘導加熱により表面温度が１００℃に達するまで加熱し、溶媒（水）を蒸発させることにより鋼管表面に表面処理層を形成した。なお、表面処理層の付着量は、以下のように推定した。別途用意し、予め質量を測定した鋼板の表面に、実施例の鋼管と同一条件で表面処理層を形成した後、その鋼板の質量を測定し、処理前の質量との差より鋼板表面に形成された表面処理層の１ｍ２当たりの質量を算出し、この質量に基づいて鋼管表面に形成された表面処理層の付着量を推定した。
次いで、表面処理層の上に、市販の液状エポキシ樹脂（三菱化学（株）製「基本液状タイプ828」）と硬化剤（三菱化学（株）製「変性脂肪族アミングレードＴ」）を混合したエポキシプライマーを膜厚が４０μｍとなるようにスプレー塗布し、誘導加熱により硬化させた後、市販の接着性ポリエチレン樹脂（三井化学（株）製「アドマーNE065」）、ポリエチレン樹脂（プライムポリマー（株）製「HI-ZEX5100E」）を押出被覆により被覆してポリエチレン被覆鋼管を作製した。
[Production of polyethylene-coated steel pipe]
Steel pipe is JIS SGP
The size was 80A, and the black skin was removed by blasting. After applying a certain amount of a surface treatment agent to the outer surface of the steel pipe, it was heated by induction heating until the surface temperature reached 100 ° C., and the solvent (water) was evaporated to form a surface treatment layer on the steel pipe surface. In addition, the adhesion amount of the surface treatment layer was estimated as follows. Separately, after forming a surface treatment layer on the surface of the steel plate whose mass was measured in advance under the same conditions as the steel pipe of the example, measure the mass of the steel plate and form it on the steel plate surface from the difference from the mass before treatment The mass per 1 m 2 of the surface treatment layer thus formed was calculated, and the adhesion amount of the surface treatment layer formed on the steel pipe surface was estimated based on this mass.
Next, a commercially available liquid epoxy resin (“Basic Liquid Type 828” manufactured by Mitsubishi Chemical Corporation) and a curing agent (“Modified Aliphatic Amine Grade T” manufactured by Mitsubishi Chemical Corporation) were mixed on the surface treatment layer. Epoxy primer is spray-coated to a thickness of 40 μm, cured by induction heating, then commercially available adhesive polyethylene resin (“Admer NE065” manufactured by Mitsui Chemicals), polyethylene resin (Prime Polymer Co., Ltd.) "HI-ZEX5100E") was coated by extrusion coating to produce a polyethylene-coated steel pipe.
参考例としてクロメート処理材によるポリエチレン被覆鋼管を作製した。上記の表面処理剤の代わりに、クロメート処理液（関西ペイント（株）製「コスマー１００」）を純水で１／５に希釈したものを使用し、鋼管外面にＣｒ換算付着量が３００ｍｇ／ｍ２となるようスプレー塗布し、鋼管到達温度が１００℃となるよう加熱乾燥させてクロメート層を形成した。それ以外は、他の実施例と同様とし、ポリエチレン被覆鋼管を作製した。Ｃｒ換算付着量は、上記と同じ方法でクロメート層を形成したダミー板を作製し、所定面積のクロメート皮膜を１０％ＮａＯＨで剥離した後、剥離溶液中のＣｒ量を吸光光度法で測定し、これを元に１ｍ２当たりのＣｒ換算付着量を算出した。 As a reference example, a polyethylene-coated steel pipe made of a chromate treatment material was prepared. Instead of the above-mentioned surface treatment agent, a chromate treatment solution (“Cosmer 100” manufactured by Kansai Paint Co., Ltd.) diluted to 1/5 with pure water is used, and the Cr conversion adhesion amount is 300 mg / m on the outer surface of the steel pipe. It was applied by spraying to a temperature of 2, and dried by heating so that the temperature reached by the steel pipe was 100 ° C. to form a chromate layer. Other than that was carried out similarly to the other Example, and produced the polyethylene covering steel pipe. The amount of Cr equivalent adhesion was prepared by preparing a dummy plate having a chromate layer formed by the same method as described above, peeling the chromate film of a predetermined area with 10% NaOH, and then measuring the Cr amount in the stripping solution by absorptiometry, Based on this, the Cr conversion adhesion amount per 1 m 2 was calculated.
［ポリエチレン被覆鋼管及び表面処理剤の性能評価］
（１）耐陰極剥離性（陰極剥離距離）
ポリエチレン被覆鋼管から適当な大きさの試験片を採取し、以下の方法で陰極剥離距離を測定し、耐陰極剥離性を評価した。試験片の中央部に直径６ｍｍφの円形の人工欠陥部を形成し、鋼管を露出させた。人工欠陥部を中心にして直径７０ｍｍφのアクリル製の円筒を樹脂被覆層上に縦に設置してシール材で樹脂被覆層に固定し、円筒内部を３質量％ＮａＣｌ水溶液で満たし、セルを作成した。対極に白金を使用して人工欠陥部の鋼材の電位を−１.５Ｖ vsSCEにポテンシオスタットを使用して保持した。このまま６０℃の恒温槽内に試験片を静置し、２８日間電位を保持した。次いで、試験片を回収後、セルをはずし、人工欠陥部の周囲をたがねとカッターを使用して強制的に剥離した。人工欠陥周辺部は樹脂被覆層が鋼管から剥離し、鋼管の表面が露出していたため、人工欠陥部からの剥離距離を調べるため、人工欠陥部を中心とした４方向（管軸方向を１２時方向として、１２時、３時、６時、９時方向)で人工欠陥端部からの剥離部の距離を測定して、その平均値を陰極剥離距離とした。この陰極剥離距離は、値が小さいほど良好であり、「２０ｍｍ以下」を合格とした。
[Performance evaluation of polyethylene-coated steel pipe and surface treatment agent]
(1) Cathodic stripping resistance (cathode stripping distance)
A test piece of an appropriate size was taken from the polyethylene-coated steel tube, and the cathode peeling distance was measured by the following method to evaluate the cathode peeling resistance. A circular artificial defect with a diameter of 6 mmφ was formed at the center of the test piece to expose the steel pipe. An acrylic cylinder having a diameter of 70 mmφ centered on the artificial defect portion was vertically installed on the resin coating layer, fixed to the resin coating layer with a sealing material, and the inside of the cylinder was filled with a 3 mass% NaCl aqueous solution to form a cell. . Platinum was used as the counter electrode, and the potential of the steel material at the artificial defect portion was held at -1.5 V vs SCE using a potentiostat. The test piece was left still in a constant temperature bath at 60 ° C., and the potential was maintained for 28 days. Next, after collecting the test piece, the cell was removed, and the periphery of the artificial defect portion was forcibly separated using a chisel and a cutter. Since the resin coating layer was peeled from the steel pipe and the surface of the steel pipe was exposed at the artificial defect peripheral part, in order to investigate the peel distance from the artificial defect part, four directions centered on the artificial defect part (the pipe axis direction was 12:00) As the direction, the distance of the peeled portion from the edge of the artificial defect was measured at 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock), and the average value was taken as the cathode peeling distance. The smaller the value of the cathode peeling distance, the better, and “20 mm or less” was considered acceptable.
（２）塗装性（貯蔵安定性）
調製直後の表面処理剤の粘度を測定し、さらに常温で１０日放置した後の粘度を測定した。１０日放置後の粘度が調製直後の粘度の３倍以下であった場合を塗装性良好「○」、３倍を越えていた場合を塗装可能だが取り扱い不良「△」とした。また、「△」のなかでも塗装性が相対的に良いものは「△+」とした。一方、ゲル化したものは塗装せず、評価対象外とした。
以上の評価結果を、ポリエチレン被覆鋼管の製造条件ととともに表１〜表１０に示す。これによれば、本発明例では、比較例に較べて優れた耐陰極剥離性（陰極剥離距離が小さい）が得られている。また、本発明例では、クロメート処理材（参考例）とほぼ同等の優れた性能が得られている。
(2) Paintability (storage stability)
The viscosity of the surface treatment agent immediately after the preparation was measured, and the viscosity after standing at room temperature for 10 days was measured. When the viscosity after standing for 10 days was not more than 3 times the viscosity immediately after preparation, the coating property was good “◯”, and when the viscosity was more than 3 times, the coating was possible but the handling was poor “Δ”. Among “△”, those having relatively good paintability were designated as “△ +”. On the other hand, the gelled one was not painted and excluded from the evaluation.
The above evaluation results are shown in Tables 1 to 10 together with the production conditions of the polyethylene-coated steel pipe. According to this, in the example of the present invention, excellent cathode peel resistance (cathode peel distance is small) compared to the comparative example is obtained. Moreover, in the example of this invention, the outstanding performance substantially equivalent to the chromate processing material (reference example) is obtained.
Claims (2)
該表面処理層の上に、下層側から順に、エポキシ系プライマー樹脂層、接着性ポリエチレン樹脂層及びポリエチレン樹脂層を有すること特徴とするポリエチレン被覆鋼管。 Silane cup having silica (A), aluminum phosphate (B), titanium peroxide (C), organic phosphonic acid compound (D), zirconyl ammonium carbonate (E) and epoxy group as organic functional group on the surface of the steel pipe Containing a ring agent (H), the silane coupling agent (H) comprising at least one selected from 3-glycidoxypropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane, The proportion of silica (A) is 40 to 50 parts by mass and the proportion of aluminum phosphate (B) is 10 to 100 parts by mass in total of components (A), (B), (C), (D) and (E). 30 parts by mass, 5 to 20 parts by mass of titanium peroxide (C), 6 to 24 parts by mass of organic phosphonic acid compound (D), and 2 to 2 of zirconyl ammonium carbonate (E) Parts by weight, the proportion of the silane coupling agent (H) has a surface treatment layer formed by the aqueous surface treatment agent is 5 to 40 parts by weight,
A polyethylene-coated steel pipe comprising an epoxy primer resin layer, an adhesive polyethylene resin layer, and a polyethylene resin layer in order from the lower layer side on the surface treatment layer.
該表面処理層の上に、下層側から順に、エポキシプライマー樹脂層、接着性ポリエチレン樹脂層及びポリエチレン樹脂層を有すること特徴とするポリエチレン被覆鋼管。 Silane cup having silica (A), aluminum phosphate (B), titanium peroxide (C), organic phosphonic acid compound (D), zirconyl ammonium carbonate (E) and epoxy group as organic functional group on the surface of the steel pipe Containing a ring agent (H), the silane coupling agent (H) comprising at least one selected from 3-glycidoxypropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane; , Ammonium zircon fluoride (F) and / or ammonium metavanadate (G), and the components (A), (B), (C), (D), (E), (F) and (G) The proportion of silica (A) is 40 to 50 parts by mass, the proportion of aluminum phosphate (B) is 10 to 30 parts by mass, and the proportion of titanium peroxide (C) is 5 to 100 parts by mass. 0 parts by mass, 6-24 parts by mass of the organic phosphonic acid compound (D), 2-20 parts by mass of zirconyl ammonium carbonate (E), 2-15 parts by mass of zircon ammonium fluoride (F), Having a surface treatment layer formed by an aqueous surface treatment agent having a proportion of ammonium metavanadate (G) of 2 to 10 parts by mass and a proportion of silane coupling agent (H) of 5 to 40 parts by mass;
A polyethylene-coated steel pipe having an epoxy primer resin layer, an adhesive polyethylene resin layer, and a polyethylene resin layer in order from the lower layer side on the surface treatment layer.
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