JP6920792B2 - A method for manufacturing a three-layer polyolefin resin-coated steel pipe having an end shape with excellent peel resistance. - Google Patents
A method for manufacturing a three-layer polyolefin resin-coated steel pipe having an end shape with excellent peel resistance. Download PDFInfo
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- JP6920792B2 JP6920792B2 JP2016130313A JP2016130313A JP6920792B2 JP 6920792 B2 JP6920792 B2 JP 6920792B2 JP 2016130313 A JP2016130313 A JP 2016130313A JP 2016130313 A JP2016130313 A JP 2016130313A JP 6920792 B2 JP6920792 B2 JP 6920792B2
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- 229910000831 Steel Inorganic materials 0.000 title claims description 144
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- 238000005520 cutting process Methods 0.000 claims description 27
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- 230000000052 comparative effect Effects 0.000 description 21
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- 239000008188 pellet Substances 0.000 description 14
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- 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
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- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
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- 229910010293 ceramic material Inorganic materials 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 239000011538 cleaning material Substances 0.000 description 1
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- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
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- 239000002436 steel type Substances 0.000 description 1
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- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- BIKXLKXABVUSMH-UHFFFAOYSA-N trizinc;diborate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]B([O-])[O-].[O-]B([O-])[O-] BIKXLKXABVUSMH-UHFFFAOYSA-N 0.000 description 1
- 239000006097 ultraviolet radiation absorber Substances 0.000 description 1
- 239000010456 wollastonite Substances 0.000 description 1
- 229910052882 wollastonite Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 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 1
- 229910000165 zinc phosphate Inorganic materials 0.000 description 1
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- Protection Of Pipes Against Damage, Friction, And Corrosion (AREA)
- Rigid Pipes And Flexible Pipes (AREA)
- Laminated Bodies (AREA)
Description
石油・ガス等のエネルギー輸送に用いられるラインパイプの防食用外面被覆には通常ポリオレフィン樹脂被覆鋼管が使用されるが、本発明は、この耐剥離性に優れた端部形状を有する３層ポリオレフィン樹脂被覆鋼管に関する。 A polyolefin resin-coated steel pipe is usually used for the anticorrosion outer surface coating of line pipes used for energy transportation of oil, gas, etc., but the present invention presents a three-layer polyolefin resin having an end shape excellent in peeling resistance. Regarding coated steel pipes.
ラインパイプに用いられる外面ポリオレフィン樹脂被覆鋼管において、長期の防食性と施工時の耐疵性が要求される場合には３層被覆鋼管が用いられる。その構成は防食性の高いエポキシ樹脂プライマー層、接着剤層、ポリオレフィン樹脂層からなる３層構造である。被覆されるポリオレフィン樹脂には、ポリエチレン樹脂とポリプロピレン樹脂があるが、安価で信頼性が高いことから、一般的にはポリエチレン樹脂が、高温用や耐疵性が要求される場合にはポリプロピレン樹脂が使用される。これらの３層被覆鋼管は被覆工場で生産され、現地で溶接接合を行う。 In the outer surface polyolefin resin coated steel pipe used for the line pipe, a three-layer coated steel pipe is used when long-term corrosion resistance and flaw resistance during construction are required. Its structure is a three-layer structure consisting of an epoxy resin primer layer, an adhesive layer, and a polyolefin resin layer, which have high corrosion resistance. Polyolefin resins to be coated include polyethylene resin and polypropylene resin. Since they are inexpensive and highly reliable, polyethylene resin is generally used, and polypropylene resin is used for high temperature or when flaw resistance is required. used. These three-layer coated steel pipes are produced at the coating plant and welded and joined locally.
通常、外面被覆は、現地での溶接接合時の熱影響による被覆の劣化を考慮して、管端部の被覆を除去しておくため、管端部は鋼材が露出した状態で出荷される。ラインパイプで一般的な３層ポリオレフィン樹脂被覆に行われている鋼管端部の形状を図１に示す。鋼管被覆の一番弱い部分は、当該端部であり、ここから水分が侵入し被覆の剥離を発生させる場合がある。 Usually, the outer surface coating is shipped with the steel material exposed because the coating on the pipe end is removed in consideration of the deterioration of the coating due to the heat effect at the time of welding and joining in the field. FIG. 1 shows the shape of the end of the steel pipe, which is generally coated with a three-layer polyolefin resin in a line pipe. The weakest part of the steel pipe coating is the end portion, from which moisture may enter and cause peeling of the coating.
そこで、端部の応力を小さくするために、図１に示すように被覆端部を斜めの形状にする事が一般的に行われている。特許文献１では、この斜めの形状を形成するための加工装置が示されており、特許文献２では、斜めの形状をワイヤーブラシで形成するために曲面形状が示されている。
この斜めの形状は、現場溶接接合後に鋼材が露出した部分を架橋ポリエチレンスリーブ（収縮スリーブ）で防食する際に該スリーブと鋼管被覆端部とのなじみを良くし、埋設後の地中の水侵入を防止する働きがある。この関係を図２に示す。
Therefore, in order to reduce the stress at the end portion, it is common practice to shape the coated end portion into an oblique shape as shown in FIG.
This slanted shape improves the compatibility between the sleeve and the steel pipe coating end when the cross-linked polyethylene sleeve (shrink sleeve) protects the exposed part of the steel material after on-site welding, and allows water to enter the ground after burial. It works to prevent. This relationship is shown in FIG.
しかしながら、上記対策を持ってしても長期の埋設時には完全に水の侵入を防ぐことはできない。そこで、該スリーブと鋼管被覆端部の接着性をさらに向上させて水の侵入を防止する方法として、鋼管被覆端部にポリオレフィンプライマーを塗布することが特許文献３に提案されている。しかしこの方法は、現場での工程が増える問題がある。
However, even with the above measures, it is not possible to completely prevent the ingress of water during long-term burial. Therefore,
鋼管被覆の最も弱い部分は端面であり、端面の部分に水が侵入し鋼面が腐食すると被覆が剥離していく。従って、水の侵入を完全に防止する手段があればこの問題は解決するが、水の分子は小さく、ラインパイプのように数十年間の長期に渡って供用されるインフラにあっては、水の侵入を完全に防ぐことは困難である。
従って、この水の侵入を出来るだけ小さくし、被覆の剥離に至らしめない技術の開発が要望されている。
The weakest part of the steel pipe coating is the end face, and when water invades the end face and the steel surface corrodes, the coating peels off. Therefore, this problem can be solved if there is a means to completely prevent the ingress of water, but water molecules are small, and in infrastructure that is in service for a long period of several decades such as line pipes, water It is difficult to completely prevent the invasion of water.
Therefore, there is a demand for the development of a technique that minimizes the intrusion of water and does not lead to peeling of the coating.
すなわち、本発明に関する要旨は次の通りである。
（１）鋼管表面からエポキシ樹脂プライマー層、ポリオレフィン接着剤層、ポリオレフィン層が順次積層されたポリオレフィン被覆鋼管において、当該被覆端部のポリオレフィン接着剤層、ポリオレフィン層が鋼管表面と角度４５度以下に形成され、当該端部から外側にエポキシ樹脂プライマー層のみ５ｍｍ以上塗り残されていることを特徴とする耐剥離性に優れた端部形状を有するポリオレフィン被覆鋼管。
（２）エポキシ樹脂プライマー層が粉体塗料を用いて形成され、その厚みが１５０〜６００μｍであることを特徴とする上記（１）に記載の耐剥離性に優れた端部形状を有するポリオレフィン被覆鋼管。
（３）ポリオレフィン被覆が形成されたのち、その端部をまず切削刃によってポリオレフィン接着剤層、ポリオレフィン層を鋼管表面と角度４５度以下に形成し、しかるのちにスチールブラシによってエポキシ樹脂プライマー層を５ｍｍ以上塗り残すように整えることを特徴とする上記（１）又は（２）に記載の耐剥離性に優れた端部形状を有するポリオレフィン被覆鋼管の製造方法。
That is, the gist of the present invention is as follows.
(1) In a polyolefin-coated steel pipe in which an epoxy resin primer layer, a polyolefin adhesive layer, and a polyolefin layer are sequentially laminated from the surface of the steel pipe, the polyolefin adhesive layer and the polyolefin layer at the coated end are formed at an angle of 45 degrees or less with the surface of the steel pipe. A polyolefin-coated steel tube having an end shape having excellent peel resistance, characterized in that only the epoxy resin primer layer is left uncoated on the outside from the end by 5 mm or more.
(2) The polyolefin coating having an end shape having excellent peel resistance according to the above (1), wherein the epoxy resin primer layer is formed by using a powder coating material and the thickness thereof is 150 to 600 μm. Steel pipe.
(3) After the polyolefin coating is formed, the edges thereof are first formed with a polyolefin adhesive layer and the polyolefin layer at an angle of 45 degrees or less with the steel pipe surface, and then the epoxy resin primer layer is formed with a steel brush to form an epoxy resin primer layer of 5 mm. The method for producing a polyolefin-coated steel pipe having an end shape having excellent peel resistance according to the above (1) or (2), which is prepared so as to be left uncoated.
次に、上記本発明の要旨について、その内容を記載する。
３層ポリオレフィン被覆鋼管の管端部の形状を検討した結果、ポリオレフィン被覆の端部よりプライマー部分をはみ出させて長くする事がもっとも簡便で効果が大きい事が分かった。概略を図３に示す。当該プライマー部をはみ出させて５ｍｍ上長くする（延長する）事によって、被覆の端部いわゆる鋼面と被覆の端部がプライマー部の端にまで移動する結果、鋼面に水が侵入したとしても剥離するのは当該プライマー部のみであり、被覆の剥離には至らないこととなり、長期の耐久性を有する３層ポリオレフィン被覆を得ることが出来る。
また、延長されたプライマー部には上層のポリオレフィン被覆層がないため、当該層の収縮応力が働かず剥離が起こりにくくなる。
さらに、副次的効果として、現場でポリオレフィン被覆鋼管を溶接後に防食の目的で溶接部分を収縮スリーブで被覆するが、該スリーブと延長されたプライマー部との接着性が向上し、供用中の鋼管被覆への水の侵入をなお一層防止することができる。（図４）
なお、現場でプライマーを塗布すれば一見同様の効果が得られるように考えられるが、ポリオレフィン被覆時に塗布されたプライマー層と現場で塗布したプライマー層とは完全には一体にならないため長年月の間に両層間が剥離し、ここに水が侵入することによって被覆の剥離が発生する可能性がある。
Next, the contents of the above gist of the present invention will be described.
As a result of examining the shape of the pipe end portion of the three-layer polyolefin-coated steel pipe, it was found that it is the simplest and most effective to extend the primer portion from the end portion of the polyolefin coating. The outline is shown in FIG. Even if water invades the steel surface as a result of the end of the coating, the so-called steel surface, and the end of the coating moving to the end of the primer by protruding (extending) the primer portion by 5 mm. Only the primer portion is peeled off, and the coating is not peeled off, so that a three-layer polyolefin coating having long-term durability can be obtained.
Further, since the extended primer portion does not have an upper polyolefin coating layer, the shrinkage stress of the layer does not work and peeling is less likely to occur.
Further, as a side effect, after welding the polyolefin-coated steel pipe on site, the welded portion is coated with a shrink sleeve for the purpose of corrosion protection, but the adhesiveness between the sleeve and the extended primer portion is improved, and the steel pipe in service is improved. It is possible to further prevent the ingress of water into the coating. (Fig. 4)
At first glance, it seems that the same effect can be obtained by applying the primer in the field, but for many years, the primer layer applied at the time of polyolefin coating and the primer layer applied in the field are not completely integrated. Both layers may be separated from each other, and water may enter the layers to cause the coating to be peeled off.
延長するプライマーのみの部分には高い防食性と耐加工性が要求されるため、無機顔料が２０重量％以上添加され、加熱硬化後のガラス転移温度が９５℃以上になるように樹脂成分を調整した粉体状のエポキシ樹脂を塗布して加熱硬化させ、１５０〜６００μｍの膜厚となるようにする。
なお、非晶質の固体（例えば、ポリオレフィン樹脂）を加熱した場合、低温では結晶なみに硬く（剛性が大きく）流動性がなかった固体が、ある狭い範囲で急速に剛性と粘度が低下し流動性が増す。このような温度をガラス転移温度という。従って、ガラス転移温度が高いポリオレフィン樹脂ほど、低温（常温）では硬い樹脂となる。
このようにして、無機顔料とガラス転移温度の高温化によって塗膜硬度が確保されることから、上層のポリオレフィン被覆のみを除去するのが容易となる。また、１５０μｍ以上の膜厚とすることで、加工後でもピンホールが発生しない膜厚を残存させることが可能で、防食性確保に有効となる。
Since high corrosion resistance and work resistance are required for the part containing only the primer to be extended, 20% by weight or more of an inorganic pigment is added, and the resin component is adjusted so that the glass transition temperature after heat curing becomes 95 ° C. or more. The powdery epoxy resin is applied and cured by heating so as to have a film thickness of 150 to 600 μm.
When an amorphous solid (for example, a polyolefin resin) is heated, the solid which is as hard as a crystal (high rigidity) and has no fluidity at a low temperature rapidly decreases in rigidity and viscosity in a narrow range and flows. Increases sex. Such a temperature is called a glass transition temperature. Therefore, the higher the glass transition temperature of the polyolefin resin, the harder the resin becomes at low temperature (normal temperature).
In this way, since the hardness of the coating film is secured by increasing the temperature of the inorganic pigment and the glass transition temperature, it becomes easy to remove only the polyolefin coating of the upper layer. Further, by setting the film thickness to 150 μm or more, it is possible to leave a film thickness at which pinholes do not occur even after processing, which is effective in ensuring corrosion resistance.
次に、本発明の被覆鋼管の端部の形成方法について説明する。通常、樹脂被覆鋼管の被覆端部は溶接の熱影響を避けるために、管端部から１００ｍｍ以上カットし溶接熱影響が被覆に及ばない用に鋼材露出部を設ける。この時、管端被覆端部には在る程度の斜めの形状（テーパー）加工が行われる。 Next, a method for forming the end portion of the coated steel pipe of the present invention will be described. Normally, the coated end of the resin-coated steel pipe is cut by 100 mm or more from the pipe end in order to avoid the heat effect of welding, and an exposed steel material is provided so that the heat effect of welding does not affect the coating. At this time, a certain degree of oblique shape (tapering) processing is performed on the pipe end covering end portion.
本発明の３層被覆鋼管では管端部の被覆に切削あるいはブラシ加工を行って、４５度以下のテーパー形状のポリオレフィン被覆部とそのテーパー端の延長に５〜５０ｍｍのエポキシ樹脂のプライマー層のみを残存させ、プライマー層から鋼管端部までは鋼材を露出させた加工を行う。３層の積層のうちプライマー１層のみを残す加工を行うため、最下層のエポキシ樹脂プライマーには厚みと耐切削・耐ブラシ加工性が必要となる。このため、加工に耐える厚み確保が容易な粉体エポキシ樹脂を塗装する。また、塗料としては、顔料を２０重量％以上含有し、硬化後のガラス転移温度が９５℃以上の粉体エポキシ樹脂を用いる。このときのプライマー層の厚みは１５０〜６００μｍとする。 In the three-layer coated steel pipe of the present invention, the coating of the pipe end is cut or brushed, and only a polyolefin coating having a taper shape of 45 degrees or less and an epoxy resin primer layer of 5 to 50 mm are applied to the extension of the tapered end. The steel material is exposed from the primer layer to the end of the steel pipe. Since only one primer layer is left out of the three layers, the epoxy resin primer on the bottom layer needs to have thickness and cutting / brushing resistance. Therefore, a powder epoxy resin that can easily secure a thickness that can withstand processing is applied. Further, as the paint, a powder epoxy resin containing 20% by weight or more of a pigment and having a glass transition temperature of 95 ° C. or higher after curing is used. The thickness of the primer layer at this time is 150 to 600 μm.
本発明の粉体エポキシ樹脂を用いた３層ポリオレフィン被覆鋼管において、鋼管の被覆両管端部に所定のテーパー加工とプライマー層のみを残存させる加工とを行う処理を行うことにより、現地溶接継ぎ手部の防食性を向上させる（図４）とともに、置き場保管中における被覆端部からの剥離を防止することが出来る。 In a three-layer polyolefin-coated steel pipe using the powdered epoxy resin of the present invention, a field-welded joint portion is subjected to a process of performing a predetermined taper process and a process of leaving only a primer layer on both end portions of the coated steel pipe. (FIG. 4), and it is possible to prevent peeling from the coated end portion during storage in the storage place.
以下、本発明につき詳細に説明を行なう。
本発明の３層ポリオレフィン樹脂被覆鋼管本体部分の被覆は既存の方法によって鋼管１の外面にプライマー層５、接着剤層３、ポリオレフィン樹脂層４の順に３層に形成される。
被覆に使用する鋼管に特に制限は無く、普通鋼、あるいは高合金鋼など、どのような鋼種でも適用可能である。また、サイズ、厚みの制約は設備に起因するのみである。鋼管は油等の付着がある場合は事前に除去した後に鋼管表面の錆や汚れを除去し、接着に必要な粗度を確保するためにブラスト処理を行う。ブラスト処理に用いる研掃材としては、一般的には鋼製グリッド・ショット粒を用いる。更に清浄な表面が要求される場合には、アルミナ等のセラミック素材を用いても良い。ブラスト処理後の表面に、鉄粉等の汚れが付着している場合、ブラシ、吸引、液体による洗浄等の処理を行うことができる。
Hereinafter, the present invention will be described in detail.
The coating of the main body of the three-layer polyolefin resin-coated steel pipe of the present invention is formed on the outer surface of the
The steel pipe used for coating is not particularly limited, and any steel type such as ordinary steel or high alloy steel can be applied. Moreover, the restrictions on size and thickness are only due to the equipment. If oil or the like adheres to the steel pipe, it is removed in advance, and then rust and dirt on the surface of the steel pipe are removed, and blasting is performed to secure the roughness required for adhesion. As the cleaning material used for the blasting treatment, steel grid shot grains are generally used. If a cleaner surface is required, a ceramic material such as alumina may be used. If dirt such as iron powder adheres to the surface after the blasting treatment, treatments such as brushing, suctioning, and cleaning with a liquid can be performed.
次に、洗浄処理、あるいは化成処理を行う。化成処理はリン酸やその他の処理を使用する事が出来るが、特に高い防食性能が要求される場合には、例えば日本パーカーライジング社製のパルクロム１００などを用いて塗布型クロメート化成処理を行っても良い。 Next, a cleaning treatment or a chemical conversion treatment is performed. Phosphoric acid or other treatments can be used for the chemical conversion treatment, but when particularly high anticorrosion performance is required, a coating type chromate chemical conversion treatment is performed using, for example, Parchrome 100 manufactured by Nippon Parker Rising Co., Ltd. Is also good.
次に、エポキシ樹脂プライマー層について説明する。プライマー層５には本発明の管端被覆構造を得るのに必要な１５０μｍ以上の膜厚と加工に対する耐切削性・耐ブラシ加工性が必要である。従来使用されているような液体タイプでは耐切削性・耐ブラシ加工性向上のために無機顔料を多く入れた場合、沈降や粘度の問題が生じる。また、厚膜塗装が難しいこともあって、厚膜塗装が可能な粉体エポキシ樹脂を加熱した鋼管に静電粉体塗装して形成する。
Next, the epoxy resin primer layer will be described. The
粉体エポキシ樹脂塗料はビスフェノールＡ型エポキシ樹脂、ビスフェノールＦ型エポキシ樹脂を単独、もしくは混合し、更に多官能性のフェノールノボラック型エポキシ樹脂やハロゲン化エポキシ樹脂を組み合わせたものに、フェノール系、アミン系、イミダゾール化合物、ジシアンジアミドといった硬化剤を添加して調整されているものが用いられるが、本発明で必要とされる特性としては切削、あるいはブラシ加工時の膜の耐久性である。そのため、粉体エポキシ樹脂紛体塗料としては無機顔料を２０〜５０重量％配合する。 The powder epoxy resin paint is a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin alone or in combination, and a combination of polyfunctional phenol novolac type epoxy resin and halogenated epoxy resin, and phenol type and amine type. , The imidazole compound, and the one adjusted by adding a curing agent such as dicyandiamide are used, but the property required in the present invention is the durability of the film during cutting or brushing. Therefore, 20 to 50% by weight of an inorganic pigment is blended as the powder epoxy resin powder coating material.
無機顔料はシリカ、酸化チタン、ウォラストナイト、マイカ、タルク、カオリン、酸化クロム、ホウ酸亜鉛、燐酸亜鉛等の顔料、もしくは亜鉛、Ａｌ等の金属粉、あるいはセラミック粉等を適宜用いることができる。また、膜の硬度は耐切削性・耐ブラシ加工性には重要であるから、塗膜の硬度を上げるために高いガラス転移温度を持った材料を使用する。具体的にはガラス転移温度としては９５℃以上になることが好ましい。 As the inorganic pigment, pigments such as silica, titanium oxide, wollastonite, mica, talc, kaolin, chromium oxide, zinc borate and zinc phosphate, metal powders such as zinc and Al, ceramic powders and the like can be appropriately used. .. Further, since the hardness of the film is important for cutting resistance and brushing resistance, a material having a high glass transition temperature is used in order to increase the hardness of the coating film. Specifically, the glass transition temperature is preferably 95 ° C. or higher.
粉体エポキシ樹脂塗料は、国内では日本ペイント株式会社、もしくは関西ペイント株式会社から入手可能で、本発明に該当するものを選択して用いる。プライマー層の厚みは１５０μｍ以上であれば良いが、厚みが厚くなりすぎると塗膜の内部応力が増加し、昼夜又は季節の移り変わりによる冷熱繰り返しで応力が加わる場合、特に屋外での曝露で剥離し易くなることから１５０〜６００μｍが適切である。 The powder epoxy resin paint can be obtained from Nippon Paint Co., Ltd. or Kansai Paint Co., Ltd. in Japan, and the one corresponding to the present invention is selected and used. The thickness of the primer layer may be 150 μm or more, but if the thickness becomes too thick, the internal stress of the coating film increases, and when stress is applied due to repeated cooling and heating during the day and night or due to the change of seasons, it peels off especially when exposed outdoors. 150 to 600 μm is appropriate because it facilitates.
粉体エポキシ樹脂プライマー層５を形成後に、変性ポリオレフィン樹脂接着剤層３を介してポリオレフィン樹脂層４を積層する。変性ポリオレフィン樹脂接着剤は、ポリオレフィン樹脂を無水マレイン酸で変性したもの、あるいはポリオレフィンと無水マレイン酸との共重合体、ポリオレフィンとアクリル酸エステルと、無水マレイン酸との共重合体を用いることができる。
After forming the powder epoxy
変性ポリオレフィン樹脂接着剤は、粉体あるいはペレットで供給される。ポリエチレン被覆に使用する接着剤としては、例えば三井化学社製のNE060,NE065,NE080、BOREALIS社製のBorcoat ME0420、Lyondell Basell社製のLucalen G3710E等が使用できる。ペレットの場合、接着剤押出機を用いて加熱溶融した樹脂を、Ｔダイスを用いてプライマー塗布後の鋼管外面に被覆する。中小径鋼管では丸ダイスを用いる場合もある。その他の方法としては、変性ポリオレフィン樹脂接着剤を粉砕して粉体化し、この粉体を塗布する方法もある。これらの方法により、０．１〜０．４ｍｍの接着剤層を形成する。 The modified polyolefin resin adhesive is supplied as a powder or pellets. As the adhesive used for polyethylene coating, for example, NE060, NE065, NE080 manufactured by Mitsui Chemicals, Borcoat ME0420 manufactured by BOREALIS, Lucalen G3710E manufactured by Lyondell Basell and the like can be used. In the case of pellets, the resin heated and melted by using an adhesive extruder is coated on the outer surface of the steel pipe after applying the primer using a T-die. Round dies may be used for small and medium diameter steel pipes. As another method, there is also a method of crushing the modified polyolefin resin adhesive into powder and applying this powder. By these methods, an adhesive layer of 0.1 to 0.4 mm is formed.
変性ポリオレフィン接着剤層３の上に被覆するポリオレフィン樹脂は、鋼管被覆用として市販されているものを使用することができる。代表的なポリオレフィンはポリエチレンであり、その他には高温用にポリプロピレンが用いられる。ポリエチレン樹脂としては鋼管被覆用に用いられる銘柄を使用することができる。例えば、国内では日本ポリエチレン社製のNOVATEC ER002S、海外では BOREALIS社製のBorcoat HE3450、Lyondell Basell社製のLupolen 4552Dなどの、鋼管被覆に要求される長期耐久性を有し、カーボンブラックを添加したものが使用可能である。
As the polyolefin resin to be coated on the modified
ポリプロピレン樹脂としては一般的にはホモポリマーよりも低温特性に優れる共重合体が使用され、耐熱性と耐候性対策として、着色顔料、充填強化剤、酸化防止剤、紫外線吸収剤、ヒンダードアミン系の耐候剤等が添加されたもので、低温靭性と高温使用での耐酸化劣化性を兼ね備えたものであることが好ましい。ポリプロピレン樹脂での着色顔料としてカーボンブラックを用いると、高温で酸化防止剤の効果が消失するため、高性能の被覆鋼管品では用いられない。このため、着色顔料の色としては白色が一般的である。ポリプロピレン樹脂は、例えば国内では日本ポリプロピレンのTX1843B、海外ではBOREALIS社製のBorcoat BB108E-1199、LyondellBasell社製のMoplen Coat EP60R/BIANCOといった鋼管被覆用の樹脂が使用出来る。 As a polypropylene resin, a copolymer having better low temperature characteristics than a homopolymer is generally used, and as heat resistance and weather resistance measures, a coloring pigment, a filling strengthening agent, an antioxidant, an ultraviolet absorber, and a hindered amine-based weather resistance are used. It is preferably one to which an agent or the like is added, which has both low-temperature toughness and oxidative deterioration resistance in high-temperature use. When carbon black is used as a coloring pigment in polypropylene resin, the effect of the antioxidant disappears at high temperatures, so that it is not used in high-performance coated steel pipe products. Therefore, white is generally used as the color of the coloring pigment. As the polypropylene resin, for example, a resin for coating steel pipes such as TX1843B of Japanese polypropylene in Japan, Borcoat BB108E-1199 manufactured by BOREALIS, and Moplen Coat EP60R / BIANCO manufactured by Lyondell Basell can be used overseas.
ポリオレフィン樹脂層４は取り扱い時の疵発生を抑制するため、通常２ｍｍ以上被覆される。ポリオレフィン樹脂層は厚い程、耐疵性と防食性に優れるが、厚膜になると内部応力が大きくなるため、６ｍｍ以下が望ましい。
The
以下に図３に示す本発明のテーパー形状を有する管端被覆部と、その延長にプライマー層５を有する管端部構造の形成方法の一例を述べる。３層ポリオレフィン樹脂被覆鋼管を製造した後、図５に示すように鋼管を回転させながら、ポリオレフィン被覆部が斜め（テーパー）になるような角度を持ち、かつ、プライマーと接着剤の界面を切削可能とするために鋼管に対して平行な形状の切削刃８を、表面から内部に押し込んで切削加工を実施する。これにより、ポリオレフィン樹脂被覆部には４５度以下の一定の角度を有するテーパー断面を形成し、且つプライマーのみを残す加工が可能である。
An example of a method for forming a tube end covering portion having a tapered shape of the present invention shown in FIG. 3 and a tube end portion structure having a
次いで、図６に示すように回転ワイヤーブラシ９によって被覆を完全に削りとって、管端部から１００ｍｍ以上の鋼管露出部（カットバック）を形成する。一般的なカットバックの場合、１５０ｍｍを確保する。最後に図３で形成した延長部のプライマー層の上に接着剤が残存していると現地防食との接着性を阻害するので、必要に応じて、プライマー面をワイヤーブラシ等で研磨して残存接着剤をはぎ取って仕上げる。 Next, as shown in FIG. 6, the coating is completely scraped off by the rotating wire brush 9 to form a steel pipe exposed portion (cutback) of 100 mm or more from the pipe end portion. In the case of a general cutback, secure 150 mm. Finally, if the adhesive remains on the primer layer of the extension portion formed in FIG. 3, the adhesiveness with the on-site anticorrosion is hindered. Therefore, if necessary, the primer surface is polished with a wire brush or the like and remains. Peel off the adhesive to finish.
プライマー単層部分はパイプラインの供用中に水の侵入がポリオレフィン被覆部まで到達しない距離があれば良く、最低でも５ｍｍの延長が必要である。また最大長さに特に制約は無いが、長すぎると加工が困難であることと、カットバック距離との関係にもよるが被覆端部の鋼材露出部を標準の１５０ｍｍとすると、プライマーを５０ｍｍ以上延長すると現地溶接時に溶接の熱影響を受けやすい１００ｍｍ以内（溶接部からの距離）となってしまうことから５０ｍｍまでとし、５〜５０ｍｍを適切な範囲とした。 The primer single layer portion may be extended at least 5 mm as long as there is a distance that water does not reach the polyolefin coating during the operation of the pipeline. There is no particular restriction on the maximum length, but if it is too long, it will be difficult to process, and depending on the relationship with the cutback distance, if the exposed steel material at the coated end is the standard 150 mm, the primer will be 50 mm or more. If it is extended, it will be within 100 mm (distance from the welded part), which is easily affected by the heat of welding during on-site welding, so the range was set to 50 mm, and 5 to 50 mm was set as an appropriate range.
〔実施例１〜５〕
以下、本発明のポリオレフィンにポリエチレンを使用し、テーパー角度、プライマーの塗装厚みを変えた実施例１〜５を具体的に説明する。
鋼管は２００ＡのＪＩＳ Ｇ３４５２の配管用炭素鋼管５．５ｍ長を用いた。鋼管外面にIKK社製のTGD−70番のグリッドブラスト処理を行って除錆したものを用意した。その後、鋼管の表面洗浄処理を行って汚れや鉄粉等を除去した。
鋼管を加熱装置で２２０℃に加熱後、粉体エポキシ樹脂プライマー（BASEPOX PE50-1081、Arsonsisi社製、顔料添加量27%、ガラス転移温度102℃）を、本発明の膜厚範囲である１５０〜６００μｍで静電粉体塗装を実施した後にポリエチレン接着剤として三井化学社製のNE065のペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。次いで、ポリエチレン被覆には日本ポリエチレン社製のNOVATEC ER002Sのペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。接着剤膜厚は０．２ｍｍ、ポリエチレン樹脂被覆は３ｍｍになるように調整した。被覆後、水冷を行って３層ポリエチレン樹脂被覆鋼管を製造した。
[Examples 1 to 5]
Hereinafter, Examples 1 to 5 in which polyethylene is used as the polyolefin of the present invention and the taper angle and the coating thickness of the primer are changed will be specifically described.
As the steel pipe, a 200A JIS G3452 carbon steel pipe for piping with a length of 5.5 m was used. The outer surface of the steel pipe was prepared by performing grid blast treatment of TGD-70 manufactured by IKK to remove rust. After that, the surface of the steel pipe was cleaned to remove dirt, iron powder, and the like.
After heating the steel tube to 220 ° C with a heating device, a powder epoxy resin primer (BASEPOX PE50-1081, manufactured by Arsonsisi, pigment addition amount 27%, glass transition temperature 102 ° C) is applied to the film thickness range of the present invention from 150 to. After electrostatic powder coating was performed at 600 μm, NE065 pellets manufactured by Mitsui Chemicals Co., Ltd. were formed into a sheet-like semi-molten state using an extruder and a T-die as a polyethylene adhesive, and wound and coated. Next, for the polyethylene coating, pellets of NOVATEC ER002S manufactured by Japan Polyethylene Corporation were formed into a sheet-like semi-molten state using an extruder and a T-die, and wound and coated. The adhesive film thickness was adjusted to 0.2 mm, and the polyethylene resin coating was adjusted to 3 mm. After coating, water cooling was performed to produce a three-layer polyethylene resin-coated steel pipe.
作製した３層ポリエチレン樹脂被覆鋼管を回転させ、角度を持った刃と鋼管に平行な刃を兼ね備えた切削刃によってテーパー加工と、延長プライマー層を形成するための接着剤とポリエチレン樹脂被覆の切削加工とを同時に行った。テーパー加工の角度は本発明の範囲となる３０度と４５度の角度を選定した。この時、ポリエチレン樹脂の被覆端部は鋼管の端部から１５０ｍｍの位置になるように調整した。その後ワイヤーブラシを用いて鋼管端部から被覆を削り取って鋼面を露出させ、プライマー単層部分を２０ｍｍの長さで残存させた。プライマー単層部分についてはワイヤーブラシで表面のみを更に研削し、接着剤が表面に残存しないように仕上げ、実施例１〜５を製造した。 The produced 3-layer polyethylene resin-coated steel pipe is rotated and tapered by a cutting blade that has both an angled blade and a blade parallel to the steel pipe, and an adhesive and polyethylene resin-coated cutting process for forming an extension primer layer. And at the same time. For the taper processing angle, angles of 30 degrees and 45 degrees, which are within the scope of the present invention, were selected. At this time, the coated end portion of the polyethylene resin was adjusted so as to be at a position 150 mm from the end portion of the steel pipe. After that, the coating was scraped off from the end of the steel pipe using a wire brush to expose the steel surface, and the primer single layer portion remained with a length of 20 mm. Only the surface of the primer single layer portion was further ground with a wire brush and finished so that the adhesive did not remain on the surface, and Examples 1 to 5 were manufactured.
〔実施例６〜８〕
以下、本発明のポリオレフィンにポリプロピレンを使い、プライマー延長部の長さを変えた場合の実施例６〜８を具体的に説明する。
鋼管は２００ＡのＪＩＳ Ｇ３４５２の配管用炭素鋼管５．５ｍ長を用いた。鋼管外面にIKK社製のTGD−70番のグリッドブラスト処理を行って除錆したものを用意した。その後、鋼管の表面洗浄処理を行って汚れや鉄粉等を除去した。
鋼管を加熱装置で２２０℃に加熱後、粉体エポキシ樹脂プライマー（Scotchkote 226N+、３M社製、顔料添加量44%、ガラス転移温度106℃）を、本発明の膜厚範囲である３００μｍで静電粉体塗装を実施した後に接着剤として三菱化学のAP−P501のペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。次いで、ポリプロピレン被覆には日本ポリプロピレンのTX1843Bのペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。接着剤膜厚は０．２ｍｍ、ポリプロピレン樹脂被覆は３ｍｍになるように調整した。被覆後、水冷を行って３層ポリプロピレン樹脂被覆鋼管を製造した。
[Examples 6 to 8]
Hereinafter, Examples 6 to 8 in the case where polypropylene is used as the polyolefin of the present invention and the length of the primer extension portion is changed will be specifically described.
As the steel pipe, a 200A JIS G3452 carbon steel pipe for piping with a length of 5.5 m was used. The outer surface of the steel pipe was prepared by performing grid blast treatment of TGD-70 manufactured by IKK to remove rust. After that, the surface of the steel pipe was cleaned to remove dirt, iron powder, and the like.
After heating the steel tube to 220 ° C with a heating device, a powder epoxy resin primer (Scotchkote 226N +, manufactured by 3M, pigment addition amount 44%, glass transition temperature 106 ° C) is electrostatically applied at 300 μm, which is the film thickness range of the present invention. After powder coating, pellets of AP-P501 of Mitsubishi Chemical Co., Ltd. were formed into a sheet-like semi-molten state using an extruder and a T-die as an adhesive, and wound and coated. Next, on the polypropylene coating, pellets of TX1843B of Japanese polypropylene were formed into a sheet-like semi-molten state using an extruder and a T-die, and wound and coated. The adhesive film thickness was adjusted to 0.2 mm, and the polypropylene resin coating was adjusted to 3 mm. After coating, water cooling was performed to produce a three-layer polypropylene resin-coated steel pipe.
作製した３層ポリプロピレン樹脂被覆鋼管を回転させ、角度を持った刃と鋼管に平行な刃を兼ね備えた切削刃によってテーパー加工と、延長プライマー層を形成するための接着剤とポリエチレン樹脂被覆の切削加工とを同時に行った。テーパー加工の角度は本発明の範囲となる４５度の角度を選定した。この時、ポリプロピレン樹脂の被覆端部は鋼管の端部から１５０ｍｍの位置になるように調整した。その後ワイヤーブラシを用いて鋼管端部から被覆を削り取って鋼面を露出させ、プライマー単層部分を調整して本発明の範囲である５〜５０ｍｍ長さで残存させた。プライマー単層部分についてはワイヤーブラシで表面のみを更に研削し、接着剤が表面に残存しないように仕上げ、実施例６〜８を製造した。 The produced 3-layer polypropylene resin-coated steel pipe is rotated and tapered by a cutting blade that has both an angled blade and a blade parallel to the steel pipe, and an adhesive and polyethylene resin-coated cutting process for forming an extension primer layer. And at the same time. For the taper processing angle, an angle of 45 degrees, which is within the range of the present invention, was selected. At this time, the coated end portion of the polypropylene resin was adjusted so as to be at a position 150 mm from the end portion of the steel pipe. After that, the coating was scraped off from the end of the steel pipe using a wire brush to expose the steel surface, and the primer single layer portion was adjusted to remain in a length of 5 to 50 mm, which is the range of the present invention. Only the surface of the primer single layer portion was further ground with a wire brush and finished so that the adhesive did not remain on the surface, and Examples 6 to 8 were manufactured.
〔比較例１〜３〕
以下、本発明のポリオレフィンにポリエチレンを使用し、テーパーの無い場合を比較例１、プライマー単層部が無いか又は小さい場合を比較例２及び３として具体的に説明する。
鋼管は２００ＡのＪＩＳ Ｇ３４５２の配管用炭素鋼管５．５ｍ長を用いた。鋼管外面にIKK社製のTGD−70番のグリッドブラスト処理を行って除錆したものを用意した。その後。鋼管の表面洗浄処理を行って汚れや鉄粉等を除去した。
鋼管を加熱装置で２２０℃に加熱後、粉体エポキシ樹脂プライマー（BASEPOX PE50-1081、Arsonsisi社製、顔料添加量27%、ガラス転移温度102℃）を、本発明の膜厚範囲である１５０μｍで静電粉体塗装を実施した後にポリエチレン接着剤として三井化学社製のNE065のペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。次いで、ポリエチレン被覆には日本ポリエチレン社製のNOVATEC ER002Sのペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。接着剤膜厚は０．２ｍｍ、ポリエチレン樹脂被覆は３ｍｍになるように調整した。被覆後、水冷を行って３層ポリエチレン樹脂被覆鋼管を製造した。
[Comparative Examples 1 to 3]
Hereinafter, the case where polyethylene is used as the polyolefin of the present invention and there is no taper will be specifically described as Comparative Example 1, and the case where the primer single layer portion is absent or small is referred to as Comparative Examples 2 and 3.
As the steel pipe, a 200A JIS G3452 carbon steel pipe for piping with a length of 5.5 m was used. The outer surface of the steel pipe was prepared by performing grid blast treatment of TGD-70 manufactured by IKK to remove rust. afterwards. The surface of the steel pipe was cleaned to remove dirt and iron powder.
After heating the steel pipe to 220 ° C with a heating device, a powder epoxy resin primer (BASEPOX PE50-1081, manufactured by Arsonsisi, pigment addition amount 27%, glass transition temperature 102 ° C) is applied at 150 μm, which is the film thickness range of the present invention. After performing electrostatic powder coating, NE065 pellets manufactured by Mitsui Chemicals Co., Ltd. were formed into a sheet-like semi-molten state using an extruder and a T-die as a polyethylene adhesive, and wound and coated. Next, for the polyethylene coating, pellets of NOVATEC ER002S manufactured by Japan Polyethylene Corporation were formed into a sheet-like semi-molten state using an extruder and a T-die, and wound and coated. The adhesive film thickness was adjusted to 0.2 mm, and the polyethylene resin coating was adjusted to 3 mm. After coating, water cooling was performed to produce a three-layer polyethylene resin-coated steel pipe.
〔比較例１〕
作製した３層ポリエチレン樹脂被覆鋼管を回転させ、９０度の角度を持った刃と鋼管に平行な刃を兼ね備えた切削刃による加工と、延長プライマー層を形成するための接着剤とポリエチレン樹脂被覆の切削加工とを同時に行った。この時、ポリエチレン樹脂の被覆端部は鋼管の端部から１５０ｍｍの位置になるように調整した。その後ワイヤーブラシを用いて鋼管端部から被覆を削り取って鋼面を露出させ、プライマー単層部分を５ｍｍの長さで残存させた。プライマー単層部分についてはワイヤーブラシで表面のみを更に研削し、接着剤が表面に残存しないように仕上げ、比較例１を製造した。
[Comparative Example 1]
The prepared 3-layer polyethylene resin-coated steel pipe is rotated and processed with a cutting blade that has a blade with an angle of 90 degrees and a blade parallel to the steel pipe, and an adhesive for forming an extension primer layer and a polyethylene resin coating. Cutting was performed at the same time. At this time, the coated end portion of the polyethylene resin was adjusted so as to be at a position 150 mm from the end portion of the steel pipe. After that, the coating was scraped off from the end of the steel pipe using a wire brush to expose the steel surface, and the primer single layer portion remained with a length of 5 mm. Only the surface of the primer single layer portion was further ground with a wire brush and finished so that the adhesive did not remain on the surface, and Comparative Example 1 was manufactured.
〔比較例２〕
作製した３層ポリエチレン樹脂被覆鋼管を回転させ、４５度の角度を持った刃と鋼管に平行な刃を兼ね備えた切削刃によってテーパー加工と、延長プライマー層を形成するための接着剤とポリエチレン樹脂被覆の切削加工とを同時に行った。テーパー加工の角度は本発明の範囲となる４５度の角度を選定した。この時、ポリエチレン樹脂の被覆端部は鋼管の端部から１５０ｍｍの位置になるように調整した。その後ワイヤーブラシを用いて鋼管端部から被覆を削り取って鋼面を露出させ、プライマー単層部分を残さない（０ｍｍ）ようにして比較例２を製造した。
[Comparative Example 2]
The produced 3-layer polyethylene resin-coated steel pipe is rotated and tapered by a cutting blade that has a blade with an angle of 45 degrees and a blade parallel to the steel pipe, and an adhesive and polyethylene resin coating for forming an extension primer layer. The cutting process of was performed at the same time. For the taper processing angle, an angle of 45 degrees, which is within the range of the present invention, was selected. At this time, the coated end portion of the polyethylene resin was adjusted so as to be at a position 150 mm from the end portion of the steel pipe. After that, the coating was scraped off from the end of the steel pipe using a wire brush to expose the steel surface, and Comparative Example 2 was manufactured so as not to leave the primer single layer portion (0 mm).
〔比較例３〕
作製した３層ポリエチレン樹脂被覆鋼管を回転させ、４５度の角度を持った刃と鋼管に平行な刃を兼ね備えた切削刃によってテーパー加工と、延長プライマー層を形成するための接着剤とポリエチレン樹脂被覆の切削加工とを同時に行った。この時、ポリエチレン樹脂の被覆端部は鋼管の端部から１５０ｍｍの位置になるように調整した。その後ワイヤーブラシを用いて鋼管端部から被覆を削り取って鋼面を露出させ、プライマー単層部分を２ｍｍの長さで残存させて比較例３を製造した。
[Comparative Example 3]
The produced 3-layer polyethylene resin-coated steel pipe is rotated and tapered by a cutting blade that has a blade with an angle of 45 degrees and a blade parallel to the steel pipe, and an adhesive and polyethylene resin coating for forming an extension primer layer. The cutting process of was performed at the same time. At this time, the coated end portion of the polyethylene resin was adjusted so as to be at a position 150 mm from the end portion of the steel pipe. After that, the coating was scraped off from the end of the steel pipe using a wire brush to expose the steel surface, and the primer single layer portion remained with a length of 2 mm to produce Comparative Example 3.
〔比較例４〕
以下、本発明のポリオレフィンにポリエチレンを使用し、プライマー部分の厚みが異なる場合として具体的に説明する。
鋼管は２００ＡのＪＩＳ Ｇ３４５２の配管用炭素鋼管５．５ｍ長を用いた。鋼管外面にIKK社製のTGD−70番のグリッドブラスト処理を行って除錆したものを用意した。その後、鋼管の表面洗浄処理を行って汚れや鉄粉等を除去した。
鋼管を加熱装置で２２０℃に加熱後、粉体エポキシ樹脂プライマー（BASEPOX PE50-1081、Arsonsisi社製、顔料添加量27%、ガラス転移温度102℃）を、本発明の膜厚範囲から外れる１００μｍで静電粉体塗装を実施した後にポリエチレン接着剤として三井化学社製のNE065のペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。次いで、ポリエチレン被覆には日本ポリエチレン社製のNOVATEC ER002Sのペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。接着剤膜厚は０．２ｍｍ、ポリエチレン樹脂被覆は３ｍｍになるように調整した。被覆後、水冷を行って３層ポリエチレン樹脂被覆鋼管を製造した。
[Comparative Example 4]
Hereinafter, a case where polyethylene is used as the polyolefin of the present invention and the thickness of the primer portion is different will be specifically described.
As the steel pipe, a 200A JIS G3452 carbon steel pipe for piping with a length of 5.5 m was used. The outer surface of the steel pipe was prepared by performing grid blast treatment of TGD-70 manufactured by IKK to remove rust. After that, the surface of the steel pipe was cleaned to remove dirt, iron powder, and the like.
After heating the steel pipe to 220 ° C with a heating device, a powder epoxy resin primer (BASEPOX PE50-1081, manufactured by Arsonsisi, pigment addition amount 27%, glass transition temperature 102 ° C) is applied at 100 μm outside the film thickness range of the present invention. After performing electrostatic powder coating, NE065 pellets manufactured by Mitsui Chemicals Co., Ltd. were formed into a sheet-like semi-molten state using an extruder and a T-die as a polyethylene adhesive, and wound and coated. Next, for the polyethylene coating, pellets of NOVATEC ER002S manufactured by Japan Polyethylene Corporation were formed into a sheet-like semi-molten state using an extruder and a T-die, and wound and coated. The adhesive film thickness was adjusted to 0.2 mm, and the polyethylene resin coating was adjusted to 3 mm. After coating, water cooling was performed to produce a three-layer polyethylene resin-coated steel pipe.
作製した３層ポリエチレン樹脂被覆鋼管を回転させ、４５度の角度を持った刃と鋼管に平行な刃を兼ね備えた切削刃によってテーパー加工と、延長プライマー層を形成するための接着剤とポリエチレン樹脂被覆の切削加工とを同時に行った。この時、ポリオレフィン樹脂の被覆端部は鋼管の端部から１５０ｍｍの位置になるように調整した。その後ワイヤーブラシを用いて鋼管端部から被覆を削り取って鋼面を露出させ、プライマー単層部分を４ｍｍの長さで残存させて比較例４を製造した。 The produced 3-layer polyethylene resin-coated steel pipe is rotated and tapered by a cutting blade that has a blade with an angle of 45 degrees and a blade parallel to the steel pipe, and an adhesive and polyethylene resin coating for forming an extension primer layer. The cutting process of was performed at the same time. At this time, the coated end portion of the polyolefin resin was adjusted so as to be at a position 150 mm from the end portion of the steel pipe. After that, the coating was scraped off from the end of the steel pipe using a wire brush to expose the steel surface, and the primer single layer portion remained with a length of 4 mm to produce Comparative Example 4.
〔比較例５〕
以下、本発明のポリオレフィンにポリエチレンを使用し、プライマー部分のガラス転移温度が不足した場合として具体的に説明する。
鋼管は２００ＡのＪＩＳ Ｇ３４５２の配管用炭素鋼管５．５ｍ長を用いた。鋼管外面にIKK社製のTGD−70番のグリッドブラスト処理を行って除錆したものを用意した。その後、鋼管の表面洗浄処理を行って汚れや鉄粉等を除去した。
鋼管を加熱装置で２２０℃に加熱後、粉体エポキシ樹脂プライマー（国内試作品、顔料添加量25%、ガラス転移温度91℃）を、本発明の膜厚範囲の１５０μｍで静電粉体塗装を実施した後にポリエチレン接着剤として三井化学社製のNE065のペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。次いで、ポリエチレン被覆には日本ポリエチレン社製のNOVATEC ER002Sのペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。接着剤膜厚は０．２ｍｍ、ポリエチレン樹脂被覆は３ｍｍになるように調整した。被覆後、水冷を行って３層ポリエチエン樹脂被覆鋼管を製造した。
[Comparative Example 5]
Hereinafter, a case where polyethylene is used as the polyolefin of the present invention and the glass transition temperature of the primer portion is insufficient will be specifically described.
As the steel pipe, a 200A JIS G3452 carbon steel pipe for piping with a length of 5.5 m was used. The outer surface of the steel pipe was prepared by performing grid blast treatment of TGD-70 manufactured by IKK to remove rust. After that, the surface of the steel pipe was cleaned to remove dirt, iron powder, and the like.
After heating the steel pipe to 220 ° C with a heating device, electrostatic powder coating is applied with a powder epoxy resin primer (domestic prototype, pigment addition amount 25%, glass transition temperature 91 ° C) within the film thickness range of the present invention of 150 μm. After this, NE065 pellets manufactured by Mitsui Chemicals Co., Ltd. were formed into a sheet-like semi-molten state using an extruder and a T-die as a polyethylene adhesive, and wound and coated. Next, for the polyethylene coating, pellets of NOVATEC ER002S manufactured by Japan Polyethylene Corporation were formed into a sheet-like semi-molten state using an extruder and a T-die, and wound and coated. The adhesive film thickness was adjusted to 0.2 mm, and the polyethylene resin coating was adjusted to 3 mm. After coating, water cooling was performed to produce a three-layer polyethylene resin-coated steel pipe.
作製した３層ポリエチレン樹脂被覆鋼管を回転させ、４５度の角度を持った刃と鋼管に平行な刃を兼ね備えた切削刃によってテーパー加工と、延長プライマー層を形成するための接着剤とポリエチレン樹脂被覆の切削加工とを同時に行った。この時、ポリエチレン樹脂の被覆端部は鋼管の端部から１５０ｍｍの位置になるように調整した。その後ワイヤーブラシを用いて鋼管端部から被覆を削り取って鋼面を露出させ、プライマー単層部分を４ｍｍの長さで残存させて比較例５を製造した。 The produced 3-layer polyethylene resin-coated steel pipe is rotated and tapered by a cutting blade that has a blade with an angle of 45 degrees and a blade parallel to the steel pipe, and an adhesive and polyethylene resin coating for forming an extension primer layer. The cutting process of was performed at the same time. At this time, the coated end portion of the polyethylene resin was adjusted so as to be at a position 150 mm from the end portion of the steel pipe. After that, the coating was scraped off from the end of the steel pipe using a wire brush to expose the steel surface, and the primer single layer portion remained with a length of 4 mm to produce Comparative Example 5.
〔比較例６〕
以下、本発明のポリオレフィンにポリエチレンを使用し、プライマー部分の無機顔料の添加が不足した場合として具体的に説明する。
鋼管は２００ＡのＪＩＳ Ｇ３４５２の配管用炭素鋼管５．５ｍ長を用いた。鋼管外面にIKK社製のTGD−70番のグリッドブラスト処理を行って除錆したものを用意した。その後、鋼管の表面洗浄処理を行って汚れや鉄粉等を除去した。
鋼管を加熱装置で２２０℃に加熱後、粉体エポキシ樹脂プライマー（国内試作品、顔料添加量11%、ガラス転移温度101℃）を、本発明の膜厚範囲の１５０μｍで静電粉体塗装を実施した後にポリエチレン接着剤として三井化学社製のNE065のペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。次いで、ポリエチレン被覆には日本ポリエチレン社製のNOVATEC ER002Sのペレットを押出機とＴダイスを用いてシート状の半溶融状態に成形して巻き付け被覆を行った。接着剤膜厚は０．２ｍｍ、ポリエチレン樹脂被覆は３ｍｍになるように調整した。被覆後、水冷を行って３層ポリエチレン樹脂被覆鋼管を製造した。
[Comparative Example 6]
Hereinafter, a case where polyethylene is used as the polyolefin of the present invention and the addition of the inorganic pigment in the primer portion is insufficient will be specifically described.
As the steel pipe, a 200A JIS G3452 carbon steel pipe for piping with a length of 5.5 m was used. The outer surface of the steel pipe was prepared by performing grid blast treatment of TGD-70 manufactured by IKK to remove rust. After that, the surface of the steel pipe was cleaned to remove dirt, iron powder, and the like.
After heating the steel pipe to 220 ° C with a heating device, electrostatic powder coating is applied with a powder epoxy resin primer (domestic prototype, pigment addition amount 11%, glass transition temperature 101 ° C) within the film thickness range of the present invention of 150 μm. After this, NE065 pellets manufactured by Mitsui Chemicals Co., Ltd. were formed into a sheet-like semi-molten state using an extruder and a T-die as a polyethylene adhesive, and wound and coated. Next, for the polyethylene coating, pellets of NOVATEC ER002S manufactured by Japan Polyethylene Corporation were formed into a sheet-like semi-molten state using an extruder and a T-die, and wound and coated. The adhesive film thickness was adjusted to 0.2 mm, and the polyethylene resin coating was adjusted to 3 mm. After coating, water cooling was performed to produce a three-layer polyethylene resin-coated steel pipe.
作製した３層ポリエチレン樹脂被覆鋼管を回転させ、４５度の角度を持った刃と鋼管に平行な刃を兼ね備えた切削刃によってテーパー加工と、延長プライマー層を形成するための接着剤とポリエチレン樹脂被覆の切削加工とを同時に行った。この時、ポリオレフィン樹脂の被覆端部は鋼管の端部から１５０ｍｍの位置になるように調整した。その後ワイヤーブラシを用いて鋼管端部から被覆を削り取って鋼面を露出させ、プライマー単層部分を４ｍｍの長さで残存させて比較例６を製造した。 The produced 3-layer polyethylene resin-coated steel pipe is rotated and tapered by a cutting blade that has a blade with an angle of 45 degrees and a blade parallel to the steel pipe, and an adhesive and polyethylene resin coating for forming an extension primer layer. The cutting process of was performed at the same time. At this time, the coated end portion of the polyolefin resin was adjusted so as to be at a position 150 mm from the end portion of the steel pipe. After that, the coating was scraped off from the end of the steel pipe using a wire brush to expose the steel surface, and the primer single layer portion remained with a length of 4 mm to produce Comparative Example 6.
〔実施例、比較例の性能試験結果〕
前記方法で製造した実施例及び比較例の、鋼管の端部仕様の違いと腐食による耐剥離性との関係を確認するため、管端部から５００ｍｍ長さで切断して屋外に１年間曝露した後、ポリオレフィン被覆端部から被覆をはつって、円周上の８点の剥離長さを測定して平均剥離長さを求めた。
また、現地防食被覆における防食性を評価するため、同様に管端部から５００ｍｍ長さに鋼管を切断後、これらの鋼管を円周溶接し接合した。その後、現地防食収縮スリーブの内層６、現地防食収縮スリーブの外層７からなるポリエチレン樹脂製収縮スリーブにて現地防食被覆を実施し、腐食評価用の模擬現地継ぎ手部を作製した。現地継ぎ手部の防食性については、促進試験として８０℃の塩水に９０日間試験体を浸漬した後、継ぎ手部の現地防食被覆を除去しさらに上記と同様にポリオレフィン被覆端部から被覆をはつって、円周上の８点の剥離長さを測定して平均剥離長さを求めた。
[Performance test results of Examples and Comparative Examples]
In order to confirm the relationship between the difference in the end specification of the steel pipe and the peeling resistance due to corrosion between the examples and the comparative examples manufactured by the above method, the pipe was cut to a length of 500 mm from the end and exposed to the outdoors for one year. After that, the coating was peeled off from the end of the polyolefin coating, and the peeling lengths at eight points on the circumference were measured to obtain the average peeling length.
Further, in order to evaluate the anticorrosion property of the on-site anticorrosion coating, the steel pipes were similarly cut to a length of 500 mm from the pipe end portion, and then these steel pipes were circumferentially welded and joined. Then, on-site anticorrosion coating was carried out with a polyethylene resin shrinkage sleeve composed of an
上記試験結果について実施例、比較例を表１にまとめた。
表１の本発明の実施例の結果からも明らかな様に、ポリオレフィン被覆にテーパー形状加工を行い、その先端にプライマー層のみを残存させた本発明では、被覆の端部の剥離応力が小さいだけで無く、腐食剥離も残存プライマーによって抑制されることから、屋外に１年間曝露しても剥離を生じない。更に、現地防食が２層被覆であっても、プライマーが残存することによって３層となる部分が円周状の両端に出来ることから、腐食因子である水やイオンが鋼材と現地被覆の接着界面に到達しづらいため、促進試験においてもポリオレフィン被覆の端部剥離が発生しなかった。
Examples and comparative examples of the above test results are summarized in Table 1.
As is clear from the results of the examples of the present invention in Table 1, in the present invention in which the polyolefin coating is tapered and only the primer layer remains at the tip thereof, the peel stress at the end of the coating is small. In addition, since corrosion peeling is also suppressed by the residual primer, peeling does not occur even when exposed outdoors for one year. Furthermore, even if the on-site anticorrosion is a two-layer coating, the remaining primer creates three layers at both ends of the circumference, so that water and ions, which are corrosion factors, are the adhesive interface between the steel material and the on-site coating. Therefore, the edge peeling of the polyolefin coating did not occur even in the accelerated test.
一方、ポリオレフィン被覆端部がテーパー形状を有しない比較例１の場合には、剥離応力が端部に集中することと、現地防食が角部に十分になじまないといった問題から、防食性に問題が生じる。比較例２及び３のように、本発明に必要なプライマー残存長さが不十分であった場合、屋外曝露では腐食剥離、現地防食では管端シール効果が不十分となって剥離が生じる。
また比較例４〜６の様にプライマーに必要な膜厚や、加工による耐切削性・耐ブラシ加工性（ガラス転移温度及び無機顔料添加量）等が不足すると、プライマー残存部の防食性が低下し、結果としてポリオレフィン被覆の端部剥離が発生する。
On the other hand, in the case of Comparative Example 1 in which the polyolefin-coated end portion does not have a tapered shape, there is a problem in corrosion resistance due to the problems that the peeling stress is concentrated on the end portion and the on-site corrosion protection does not sufficiently adapt to the corner portion. Occurs. When the residual primer length required for the present invention is insufficient as in Comparative Examples 2 and 3, the corrosion peeling is caused by outdoor exposure, and the pipe end sealing effect is insufficient by the on-site anticorrosion, resulting in peeling.
Further, if the film thickness required for the primer and the cutting resistance / brushing resistance (glass transition temperature and amount of inorganic pigment added) due to processing are insufficient as in Comparative Examples 4 to 6, the corrosion resistance of the remaining primer portion is lowered. As a result, edge peeling of the polyolefin coating occurs.
以上の結果からも明らかなように、３層ポリオレフィン樹脂被覆鋼管において既存のカットバックとテーパーのみによる端部の被覆仕様では、置き場曝露と、現地被覆を行った後の防食性が十分では無かった。これに対して、本発明のプライマー部を残存させる加工を行う被覆の端部仕様では、屋外曝露で問題となる冷熱繰り返しによる剥離応力が小さく、防食性の高いプライマー部が延長被覆されていることから、曝露によってポリオレフィン被覆端部の剥離が開始する事が無く、更に現地防食においてはシール効果が高いために現地防食部の防食性を大きく向上させることが可能である。 As is clear from the above results, the existing cutback and taper-only end coating specifications for the three-layer polyolefin resin-coated steel pipe did not provide sufficient anticorrosion after storage exposure and on-site coating. .. On the other hand, in the end specification of the coating for which the primer portion of the present invention is left, the peeling stress due to repeated cooling and heating, which is a problem in outdoor exposure, is small, and the primer portion having high corrosion resistance is extendedly coated. Therefore, the peeling of the polyolefin-coated end portion does not start due to exposure, and the sealing effect is high in the on-site anticorrosion, so that the anticorrosion property of the on-site anticorrosion can be greatly improved.
１ 鋼管
２ プライマー層
３ 接着剤層
４ ポリオレフィン樹脂層
５ 延長被覆された粉体エポキシ樹脂塗装によるプライマー層
６ 現地防食収縮スリーブの内層
７ 現地防食収縮スリーブの外層
８ 被覆端部のテーパー加工とプライマー残存部上の被覆を切削除去する形状の切削刃
９ 回転ワイヤーブラシ
1
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