JPH0726708B2 - Composite pipe - Google Patents
Composite pipeInfo
- Publication number
- JPH0726708B2 JPH0726708B2 JP1040952A JP4095289A JPH0726708B2 JP H0726708 B2 JPH0726708 B2 JP H0726708B2 JP 1040952 A JP1040952 A JP 1040952A JP 4095289 A JP4095289 A JP 4095289A JP H0726708 B2 JPH0726708 B2 JP H0726708B2
- Authority
- JP
- Japan
- Prior art keywords
- polyethylene resin
- layer
- density polyethylene
- silane
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Rigid Pipes And Flexible Pipes (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、主として給湯用配管等に好適に使用される複
合管に関する。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention mainly relates to a composite pipe preferably used as a hot water supply pipe and the like.
（従来の技術） 従来、例えば、実公昭59-42550号公報に示されているよ
うに、水架橋型シラン変性ポリエチレン樹脂粉末を、該
ポリエチレン樹脂の融点以上に加熱された鋼管内面に吹
き付けて、未架橋のポリエチレン樹脂層を形成し、次い
で該ポリエチレン樹脂層を水又は熱水と接触させること
により、架橋したポリエチレン樹脂層を内面にライニン
グした鋼管は公知であった。(Prior Art) Conventionally, for example, as shown in Japanese Utility Model Publication No. 59-42550, a water-crosslinking type silane-modified polyethylene resin powder is sprayed onto the inner surface of a steel pipe heated to a temperature above the melting point of the polyethylene resin, A steel pipe having an inner surface lined with a crosslinked polyethylene resin layer by forming an uncrosslinked polyethylene resin layer and then contacting the polyethylene resin layer with water or hot water has been known.
（発明が解決しようとする課題） しかしながら、上記従来技術において、ポリエチレン樹
脂層として低密度ポリエチレン樹脂のシラン変性物を使
用した場合は、該低密度ポリエチレン樹脂の耐熱性が劣
るために、長期間高温水を通水することによって、該ポ
リエチレン樹脂層の表面が劣化を起こすという問題点が
あった。(Problems to be Solved by the Invention) However, in the above-mentioned conventional technique, when a silane-modified product of a low-density polyethylene resin is used as the polyethylene resin layer, the heat resistance of the low-density polyethylene resin is inferior, so that a high temperature is maintained for a long time. There is a problem that the surface of the polyethylene resin layer is deteriorated by passing water.
また、ポリエチレン樹脂層として高密度ポリエチレン樹
脂のシラン変性物を使用した場合は、該高密度ポリエチ
レン樹脂層は耐熱性が優れるものの、低密度ポリエチレ
ン樹脂に比べて接着性が劣るため、高温水と冷水が交互
に通水されるなどして、温度の上下が繰り返された場
合、樹脂と鋼管との熱膨張率の相違による伸縮差によっ
て、樹脂層が鋼管内面から剥離したり、ストレスクラッ
キングによって樹脂層に亀裂が発生するという問題点が
あった。Further, when a silane-modified product of a high-density polyethylene resin is used as the polyethylene resin layer, the high-density polyethylene resin layer has excellent heat resistance, but has poor adhesiveness as compared with the low-density polyethylene resin. When the temperature rises and falls repeatedly, such as when water flows alternately, the resin layer peels from the inner surface of the steel pipe due to the difference in expansion and contraction due to the difference in the coefficient of thermal expansion between the resin and the steel pipe, or the resin layer undergoes stress cracking. There was a problem that cracks occurred in the.
（課題を解決するための手段） 本発明の複合管は、上記従来品の欠点を解決するために
なされたものであって、水架橋型シラングラフト変性高
密度ポリエチレン樹脂を内層、水架橋型シラングラフト
変性低密度ポリエチレン樹脂を中間層、金属を外層とし
たことを要旨とする。(Means for Solving the Problem) The composite pipe of the present invention is made to solve the above-mentioned drawbacks of the conventional products, and comprises a water-crosslinking silane-grafted modified high-density polyethylene resin as an inner layer and a water-crosslinking silane. The gist is that the graft-modified low-density polyethylene resin is used as the intermediate layer and the metal is used as the outer layer.
即ち、高温水と接する内層には、耐熱性の優れたシラン
グラフト変性高密度ポリエチレン樹脂を配し、中間層に
は、該中間層と金属管の熱膨張率の相違によって起こる
剥離を防止するために、柔軟性を有し、且つ金属管と内
層に対して優れた接着力を有するシラングラフト変性低
密度ポリエチレン樹脂を配したことを特徴とする。That is, a silane graft-modified high-density polyethylene resin having excellent heat resistance is arranged in the inner layer in contact with high-temperature water, and in the intermediate layer, in order to prevent peeling caused by a difference in coefficient of thermal expansion between the intermediate layer and the metal tube. In addition, a silane-grafted modified low-density polyethylene resin having flexibility and excellent adhesion to the metal tube and the inner layer is arranged.
本発明において、内層であるシラングラフト変性高密度
ポリエチレン樹脂を中間層の内面に積層することによ
り、内層を直接外層である金属管に積層する場合に比べ
て、熱膨張率の相違に伴う両層の伸縮差が小さくなるの
で、内層に発生する内部応力が小さくなり、内層にスト
レスクラッキングにより亀裂やブリスターが発生するの
を防止することができる。In the present invention, by laminating the inner layer of the silane-grafted modified high-density polyethylene resin on the inner surface of the intermediate layer, both layers due to the difference in coefficient of thermal expansion are compared with the case of laminating the inner layer directly to the outer layer of the metal tube. Since the difference in expansion and contraction is small, the internal stress generated in the inner layer is small and it is possible to prevent cracks and blisters from being generated in the inner layer due to stress cracking.
本発明でいう水架橋型シラングラフト変性ポリエチレン
樹脂とは、例えばポリエチレン樹脂がシラン化合物で変
性され、水好ましくは熱水と接触させることにより、分
子間で架橋を起こすポリエチレン樹脂をいう。The water-crosslinking silane-grafted modified polyethylene resin referred to in the present invention means, for example, a polyethylene resin in which the polyethylene resin is modified with a silane compound and crosslinks between molecules when brought into contact with water, preferably hot water.
本発明において、内層に使用される高密度ポリエチレン
樹脂は、結晶化度が70％以上、優れた耐熱性を得るため
に重量平均分子量が10万以上、望ましくは20万以上であ
る。In the present invention, the high density polyethylene resin used for the inner layer has a crystallinity of 70% or more and a weight average molecular weight of 100,000 or more, preferably 200,000 or more in order to obtain excellent heat resistance.
また、該樹脂の弾性率は、温度の上下に伴う伸縮によっ
て起こるストレスクラッキングを防止するために、２×
109dyn/cm2以下、望ましくは1.5×109dyn/cm2以下であ
る。The elastic modulus of the resin is 2 × in order to prevent stress cracking caused by expansion and contraction with temperature rise and fall.
It is 10 9 dyn / cm 2 or less, preferably 1.5 × 10 9 dyn / cm 2 or less.
上記高密度ポリエチレン樹脂の結晶化度が70％未満の場
合は、該樹脂の溶融粘度が高くなるため、金属管内面へ
均一な押出被覆が難しくなり、押出被覆された樹脂層
は、その表面が平滑なものとならず、波打ったものとな
ることが実験的に確かめられている。When the crystallinity of the high-density polyethylene resin is less than 70%, the melt viscosity of the resin increases, which makes uniform extrusion coating on the inner surface of the metal pipe difficult, and the extrusion-coated resin layer has a surface It has been experimentally confirmed that it does not become smooth but wavy.
本発明において、高密度ポリエチレン樹脂は、上述した
ように、結晶化度が70％以上のものを使用するが、優れ
た接着性ならびに耐ストレスクラッキング性を得るため
には、この結晶化度は大き過ぎるので、該樹脂をシラン
グラフト変性することによって、結晶化度を低下させ、
接着性ならびに耐ストレスクラッキング性の向上を計
る。In the present invention, the high-density polyethylene resin has a crystallinity of 70% or more as described above, but the crystallinity is high in order to obtain excellent adhesion and stress cracking resistance. Therefore, the silane graft modification of the resin reduces the crystallinity,
Measures adhesion and stress cracking resistance.
前記シラングラフト変性は、高密度ポリエチレン樹脂10
0重量部に、有機珪素化合物0.1〜10重量部とラジカル発
生剤0.001〜３重量部を加えて、押出機中でグラフト化
させることにより行われる。The silane graft modification is a high-density polyethylene resin 10
It is carried out by adding 0.1 to 10 parts by weight of an organosilicon compound and 0.001 to 3 parts by weight of a radical generator to 0 part by weight and grafting in an extruder.
有機珪素化合物としては、加水分解なメトキシ基、エト
キシ基などの有機官能基を含む化合物、例えばビニルト
リメトキシシラン、ビニルトリエトキシシランなどが好
適である。As the organosilicon compound, compounds containing organic functional groups such as hydrolyzable methoxy groups and ethoxy groups, such as vinyltrimethoxysilane and vinyltriethoxysilane, are suitable.
また、ラジカル発生剤としては、ジクミルパーオキサイ
ド、ｔ−ブチルパーオキサイドなどが好適である。As the radical generator, dicumyl peroxide, t-butyl peroxide and the like are suitable.
本発明において、中間層として使用されるシラングラフ
ト変性低密度ポリエチレン樹脂は、弾性率が2.5×109dy
n/cm2以下、望ましくは２×109dyn/cm2以下である。In the present invention, the silane-grafted modified low density polyethylene resin used as the intermediate layer has an elastic modulus of 2.5 × 10 9 dy.
It is n / cm 2 or less, preferably 2 × 10 9 dyn / cm 2 or less.
低密度ポリエチレン樹脂のシラングラフト変性は、高密
度ポリエチレン樹脂の場合と同様な方法で行われる。The silane graft modification of the low density polyethylene resin is performed by the same method as in the case of the high density polyethylene resin.
本発明において使用される金属管としては、鋼管、鋳鉄
管、銅管、アルミニウム管等が挙げられるが、樹脂との
接着性の点からアルミニウム管を使用するのが好まし
い。Examples of the metal pipe used in the present invention include a steel pipe, a cast iron pipe, a copper pipe, an aluminum pipe, and the like, and it is preferable to use the aluminum pipe from the viewpoint of adhesiveness with a resin.
本発明の複合管は、金属の長尺帯状シートを徐々に断面
Ｕ字状から円管状に加工して金属管を形成しながら、金
属管になる前の位置で内部に押出金型を挿入し、金属管
に形成した位置で中間層、内層を押出して被覆すること
により連続して成形される。In the composite pipe of the present invention, a metal strip is gradually processed from a U-shaped cross section into a circular pipe to form a metal pipe, and an extrusion die is inserted into the metal pipe at a position before the metal pipe is formed. Then, the intermediate layer and the inner layer are extruded and coated at the position where they are formed on the metal tube, so that they are continuously molded.
また、本発明の複合管は、金属外層の外側にも樹脂被覆
が施されていてもよい。Further, the composite pipe of the present invention may have a resin coating on the outside of the metal outer layer.
（作用） 本発明の複合管は、水架橋型シラングラフト変性高密度
ポリエチレン樹脂を内層、水架橋型シラングラフト変性
低密度ポリエチレン樹脂を中間層、金属を外層として構
成されることにより、内層は耐熱性に優れるとともに、
中間層は内層及び外層に対する接着性が優れるので、冷
熱の繰り返しによる伸縮が起こった場合でも、層間剥離
が発生せず、内層にストレスクラッキングによる亀裂や
ブリスターが発生するのを防止する （実施例） 以下、本発明の実施例を説明するが、本発明は本実施例
に限定されるものではない。(Function) The composite pipe of the present invention is composed of a water-crosslinking type silane-grafted modified high-density polyethylene resin as an inner layer, a water-crosslinking type silane-grafted modified low-density polyethylene resin as an intermediate layer, and a metal as an outer layer. It excels in
Since the intermediate layer has excellent adhesion to the inner and outer layers, delamination does not occur even when expansion and contraction due to repeated cold and heat occur, and cracks and blisters due to stress cracking in the inner layer are prevented (Example) Examples of the present invention will be described below, but the present invention is not limited to these examples.
実験例 厚さ1.5mmのアルミニウム長尺帯状板を円筒状に曲げ加
工した後、接合部を溶接して内径80mmのアルミニウム管
を連続成形し、これを外層とした。Experimental Example A long aluminum strip having a thickness of 1.5 mm was bent into a cylindrical shape, and then a joint portion was welded to continuously form an aluminum tube having an inner diameter of 80 mm, which was used as an outer layer.
このアルミニウム管の内面に、中間層として、密度が0.
935、重量平均分子量が6.8万、弾性率が1.77×109dyn/c
m2、厚さが0.1mmの低密度ポリエチレン樹脂のシラング
ラフト変性物を押出被覆し、更にこの内面に、内層とし
て、密度が0.964、重量平均分子量が20万、弾性率が1.2
5×109dyn/cm2、厚さが2mmの高密度ポリエチレン樹脂の
シラングラフト変性物を押出被覆して複合管を作製し
た。On the inner surface of this aluminum tube, as an intermediate layer, the density is 0.
935, weight average molecular weight 68,000, elastic modulus 1.77 × 10 9 dyn / c
m 2 , the thickness is 0.1mm, extrusion-coated with a silane-grafted modified product of a low-density polyethylene resin, and the inner surface has a density of 0.964, a weight average molecular weight of 200,000, and an elastic modulus of 1.2.
A composite pipe was prepared by extrusion coating a silane-grafted modified product of a high-density polyethylene resin having a thickness of 5 × 10 9 dyn / cm 2 and a thickness of 2 mm.
尚、シラングラフト変性は、内外層とも樹脂100重量部
に、ビニルエトキシシラン１重量部、過酸化物0.1重量
部を添加し、押出機の中で行った。The silane graft modification was carried out in an extruder by adding 1 part by weight of vinylethoxysilane and 0.1 part by weight of peroxide to 100 parts by weight of resin for both the inner and outer layers.
上記複合管から長さ50cmのカットサンプルを作成し、こ
のカットサンプルに90℃の熱水と30℃の常温水を、30分
間ずつ交互に通水する通水繰り返しテストを5000回繰り
返したが、中間層及び内層にクラックの発生がなく、外
層と中間層、及び中間層と内層との間に剥離は生じなか
った。A cut sample with a length of 50 cm was created from the above composite pipe, and hot cut water of 90 ° C. and normal temperature water of 30 ° C. were alternately passed through this cut sample for 30 minutes, and a repeated water flow test was repeated 5000 times. No cracks were generated in the middle layer and the inner layer, and no peeling occurred between the outer layer and the middle layer and between the middle layer and the inner layer.
比較例 内層にシラングラフト変性しない高密度ポリエチレン樹
脂（密度0.964、弾性率1.25×109dyn/cm2、重量平均分
子量20万）を使用したこと以外は、実施例−１と同様な
方法で複合管を作製し、実施例−１と同様な方法で通水
繰り返しテストを1000回実施した結果、内層の表面に多
数のクラックを発生した。Comparative Example A composite was prepared in the same manner as in Example 1 except that a high-density polyethylene resin (density 0.964, elastic modulus 1.25 × 10 9 dyn / cm 2 , weight average molecular weight 200,000) that was not silane-grafted was used for the inner layer. A pipe was prepared, and a water flow repeated test was conducted 1000 times in the same manner as in Example-1. As a result, many cracks were generated on the surface of the inner layer.
（発明の効果） 本発明の複合管は、水架橋型シラングラフト変性高密度
ポリエチレン樹脂を内層、水架橋型シラングラフト変性
低密度ポリエチレン樹脂を中間層、金属を外層として構
成されることにより、接着性、耐熱性及び耐ストレスク
ラッキング性に優れたものとなるので、高温水や冷水の
通水が交互に繰り返される配管に使用された場合でも、
層間に剥離がなく、内層にはクラックの発生もないの
で、給湯管として好適に使用しうる。(Effect of the invention) The composite pipe of the present invention is formed by bonding the water-crosslinking silane-grafted modified high-density polyethylene resin as the inner layer, the water-crosslinking silane-grafted modified low-density polyethylene resin as the intermediate layer, and the metal as the outer layer. Since it is excellent in heat resistance, heat resistance and stress cracking resistance, even when used in piping where hot water or cold water is alternately passed,
Since there is no peeling between layers and no cracks occur in the inner layer, it can be suitably used as a hot water supply pipe.
Claims (1)
チレン樹脂を内層、水架橋型シラングラフト変性低密度
ポリエチレン樹脂を中間層、金属を外層としてなる複合
管。1. A composite pipe comprising a water-crosslinking silane-grafted modified high-density polyethylene resin as an inner layer, a water-crosslinking silane-grafted modified low-density polyethylene resin as an intermediate layer, and a metal as an outer layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1040952A JPH0726708B2 (en) | 1989-02-21 | 1989-02-21 | Composite pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1040952A JPH0726708B2 (en) | 1989-02-21 | 1989-02-21 | Composite pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02221790A JPH02221790A (en) | 1990-09-04 |
| JPH0726708B2 true JPH0726708B2 (en) | 1995-03-29 |
Family
ID=12594833
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1040952A Expired - Fee Related JPH0726708B2 (en) | 1989-02-21 | 1989-02-21 | Composite pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0726708B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010156361A (en) * | 2008-12-26 | 2010-07-15 | Nix Inc | Resin pipe and connecting structure of resin pipe to joint |
-
1989
- 1989-02-21 JP JP1040952A patent/JPH0726708B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02221790A (en) | 1990-09-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |