JP2001330179A - Resin tube and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin tube which can sufficiently prevent the permeation of hydrocarbons and / or oxygen and can be manufactured at low cost, and a method for manufacturing the same. SOLUTION: A resin pipe is composed of a mother pipe made of a polyolefin resin and a coating layer made of a thermoplastic polymer having a resistance to permeation of hydrocarbons and / or oxygen fused to the outer surface thereof without interposing an adhesive layer. Constitute. The resin tube having the above configuration is formed by molding a mother tube made of a polyolefin resin,
It is manufactured by fusing a coating layer made of a thermoplastic polymer having resistance to permeation of hydrocarbons and / or oxygen to the outer surface of the mother pipe without passing through an adhesive layer. Further, it is also produced by co-extrusion molding a polyolefin resin to constitute a mother tube and a thermoplastic polymer having resistance to permeation of hydrocarbons and / or oxygen to constitute a coating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin pipe suitable for a water distribution pipe or a gas pipe for supplying water or hot water, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, polyethylene resin pipes and polybutene resin pipes for water distribution pipes or gas pipes have replaced conventional PVC pipes and cast iron pipes due to their long-term soundness such as corrosion resistance and simple construction. Tend to be adopted. However, polyethylene resin pipes are easily permeable to organic solvents such as gasoline and trichloroethylene, and when polyethylene resin pipes are buried in soil contaminated with these substances,
There is a concern that water or gas in the piping will be contaminated with these organic solvents.

[0003] For high-temperature water such as for hot water supply, resin tubes made of cross-linked polyethylene and resin tubes made of polybutene are frequently used due to their excellent high-temperature corrosion resistance. However, these resin tubes are easily permeable to oxygen. Increase the oxygen concentration of water in the piping,
For example, promoting corrosion of a metal pump or the like has become a problem.

In order to solve these problems, a method of providing a protective layer which is not fixed to the outer periphery of a resin pipe is disclosed in, for example,
Japanese Patent Application Laid-Open No. 10-9448 discloses that a flexible transmission prevention tube is used in Japanese Patent Application Laid-Open No. 10-2448, and that a peelable transmission prevention layer is provided on the outer periphery in a laminated manner.
No. 46892 proposes to wind an anti-permeation laminate film.

Further, as a method of winding an adhesive tape around an outer layer of a resin tube, Japanese Patent Application Laid-Open Nos.
No. 0-318448 proposes winding a metal foil tape having an adhesive layer.

Further, as a method for laminating a resin-based anti-permeation layer on a resin pipe main body, Japanese Patent Application Laid-Open No. Hei 7-314620 proposes a method of coating a protective layer of an olefin-based polyester via an adhesive layer. ing. JP-A-8-260526 proposes a resin pipe composed of a main layer made of polyolefin coated on the outside with a hydrocarbon-impermeable thermoplastic polymer, and the hydrocarbon-impermeable thermoplastic polymer is It is disclosed that the material comprises a copolymer of ethylene and vinyl alcohol, a polyamide, and a mixture of a polyamide and a polyolefin.

A method of laminating a resin-made transmission preventing layer inside a resin tube has been proposed in JP-A-56-127441, JP-A-61-83035, and JP-A-61-14.
Japanese Patent Application Laid-Open No. 0691 proposes a structure of polyolefin / EVOH layer for preventing permeation / polyolefin.

Japanese Patent Application Laid-Open Nos. 7-186310 and 8-80587 disclose an EVOH-based polymer / adhesive layer / resin tube main body as a method in which the transmission preventing layer is an outer surface and the resin tube main body is interposed with an adhesive layer. Japanese Patent Application Laid-Open No. H11-210938 proposes an intermediate polyamide / outside crosslinked polyethylene having an adhesive layer.

On the other hand, Japanese Patent Publication No. Sho 60-14695 discloses a method for forming a layer of a permeation-preventing resin composition into an olefin by blow molding as means for preventing permeation of hydrocarbons in a plastic fuel container of an automobile. Have been. According to the publication, a layered structure is obtained by so-called blow molding in which stretching is performed in one direction and in a vertical direction, and the stretching is performed by blowing. As a method for obtaining a layered structure which can be hung other than by blow molding, US Pat.
As disclosed in JP-A-88,784, a die having a shape capable of extending in one direction at the tip of the die and then extending in the vertical direction has been proposed. However, a method for obtaining a layered structure in continuous tube forming is not disclosed.

[0010]

However, JP-A-10-2458, JP-A-10-9448, and JP-A-10-1468 in which a protective layer which is not fixed to the outer periphery of the resin tube is provided.
In the method disclosed in JP-A-92-92, when a penetration defect occurs in the protective tube or the protective layer, the surrounding organic solvent quickly permeates the resin tube main body.

Japanese Patent Application Laid-Open Nos. Hei 7-2998851 and Hei 1
According to the method disclosed in Japanese Patent Publication No. 0-318448, when an organic solvent penetrates into the adhesive layer, the function of the adhesive layer is lost, and finally the permeation to the resin pipe main body occurs.

According to the method disclosed in JP-A-7-314620, in which a resin-based permeation preventing layer is laminated on a resin tube main body, it is difficult to prevent hydrocarbons and / or oxygen from permeating with polyester, and the three-layer structure is a die. The initial cost of manufacturing etc. increases. Further, in the method disclosed in JP-A-8-260526, the hydrocarbon-impermeable layer is vulnerable to water and / or alcohol, so it is necessary to further coat the olefin on the outside of the thermoplastic polymer. Is provided with a binder. As a result, at least three layers of dies are required in addition to the main body of the resin pipe in order to manufacture such a resin pipe, and to obtain a desirable structure, a structure of three types and five layers including the main body is required. The cost of the equipment, including the machine, increases significantly.

Similarly, Japanese Patent Application Laid-Open No. 56-127441,
JP-A-61-83035, JP-A-61-14069
According to the method disclosed in Japanese Patent Application Laid-Open Publication No. H11-157, there are three types and five layers in consideration of the adhesive layer, and the cost of the apparatus is greatly increased. Further, JP-A-7-18
6310, JP-A-8-80587, JP-A-11
All of the methods disclosed in -210938 require coextrusion of at least three types and three layers, which greatly increases the cost.

Further, the methods of Japanese Patent Publication No. 60-14695 and US Pat. No. 5,188,784 do not disclose a method of obtaining a layered structure in continuous tube forming.

The present invention solves the above problems of the prior art, and provides a resin tube which can sufficiently prevent the permeation of hydrocarbons and / or oxygen and can be manufactured at low cost, and a method for manufacturing the same. Aim.

[0016]

The above object is achieved by the following invention. [1] It is composed of a mother pipe made of a polyolefin-based resin and a coating layer made of a thermoplastic polymer having a resistance to permeation of hydrocarbons and / or oxygen fused to the outer surface thereof without an adhesive layer therebetween. Characteristic resin tube.

[2] The resin tube according to the above [1], wherein the mother tube is made of polyethylene or polybutene resin.

[3] In the above item [1] or [2], the coating layer comprises a polyolefin resin (b) which can be fused to the polyolefin resin (a) constituting the mother tube, and the polyolefin resin (b). ) And a mixture with a resin composition (c) having a permeability of hydrocarbon and / or oxygen smaller than that of the polyolefin-based resin (a), wherein the resin composition (c) is contained in the coating layer. A resin tube characterized in that it is present in a layered form.

[4] In the above item [3], the resin composition (c) constituting a part of the coating layer is selected from a copolymer of ethylene and vinyl alcohol, polyamide, polyester and polyacrylonitrile. A resin tube comprising one or more resins.

[5] In the above [3] or [4], the polyolefin resin (b) constituting a part of the coating layer is
A resin tube comprising a modified polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof, or a mixture of the modified polyolefin resin and a polyolefin resin.

[6] After molding a mother tube made of a polyolefin resin, a coating layer made of a thermoplastic polymer having resistance to permeation of hydrocarbons and / or oxygen is formed on the outer surface of the mother tube without an adhesive layer interposed therebetween. A method for manufacturing a resin tube, which comprises fusing.

[7] By co-extruding a polyolefin resin to form the mother tube and a thermoplastic polymer having a resistance to permeation of hydrocarbons and / or oxygen to form the coating layer, the mother tube and the thermoplastic resin are formed. A method for producing a resin tube, comprising: producing a resin tube having a coating layer fused to the outside without an adhesive layer interposed therebetween.

[8] In the above [7], the die used for co-extrusion molding has a spiral mandrel, and the helical groove formed on the outer periphery of the spiral mandrel has a groove depth from upstream to downstream. A method for manufacturing a resin tube, wherein the resin tube is formed to be shallow.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. The resin tube according to the present invention comprises a mother tube made of a polyolefin-based resin and a coating layer made of a thermoplastic polymer having a resistance to permeation of hydrocarbons and / or oxygen fused to the outer surface thereof without an adhesive layer therebetween. It is characterized by comprising.

In the present invention, by dividing the mother tube and the coating layer, the coating layer is freed from the mechanical characteristics such as impact resistance, and can be specialized in improving the permeation resistance by increasing the permeation prevention performance. .

Here, the mother pipe made of polyolefin resin is preferably made of polyethylene or polybutene resin. This is because these are chemically stable substances and have long-term durability.

The coating layer made of the thermoplastic polymer is made of a polyolefin resin (b) which can be fused to the polyolefin resin (a) constituting the mother tube, and a polyolefin resin (b) compatible with the polyolefin resin (b). And a mixture with a resin composition (c) having a permeability of hydrocarbon and / or oxygen smaller than that of the polyolefin resin (a), wherein the resin composition (c) is present in a layer form in the coating layer. It is preferable that

Since the resin composition (c) having a permeability of hydrocarbon and / or oxygen smaller than that of the polyolefin resin (a) constituting the mother tube is present in the coating layer as a layer, the layer is formed. Effectively prevents hydrocarbons and / or oxygen from penetrating into the resin tube from the outside, and the polyolefin-based resin (b) of the coating layer serves as a protective layer for the layered body. Furthermore, since the polyolefin-based resin (b) contained in the coating layer can be fused with the polyolefin-based resin (a) forming the main layer, a strong bonding can be achieved without the interposition of an adhesive layer.

The resin composition (c) includes a copolymer of ethylene and vinyl alcohol, a polyamide,
It is preferable to use one or more resins selected from polyester and polyacrylonitrile. This is because they have a strong polarity, a strong affinity for oxygen, and an effective permeation preventing function for hydrocarbons and oxygen.

The polyolefin resin (b) contained in the coating layer may be a modified polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof, or a mixture of the modified polyolefin resin and a polyolefin resin. Preferably, it is used. This is because these have an affinity for both the polyolefin-based resin (a) and the resin composition (c) that constitute the mother tube, and enable stronger bonding.

The resin tube having the structure described above is, for example, shown in FIG.
Can be manufactured by using the die shown in FIG.

The die 10 shown in FIG.
A mandrel 1 arranged inside the die ring 2 and a die head 6 attached to the tip of the die ring 2
The mandrel 1 is composed of a spiral mandrel 1b and a spiral mandrel 1a disposed so as to surround a part of the spiral mandrel 1b.

The distributor 8 constituting the die 10 is connected to an extruder (not shown), and the molten resin extruded from the extruder passes through a plurality of radial grooves 5 provided in the distributor 8. ,
It is introduced into a helical groove 3 formed on the outer periphery of the spiral mandrel 1a and a helical groove 4 formed on the outer periphery of the spiral mandrel 1b. Here, the helical grooves 3, 4 formed on the outer periphery of the spiral mandrels 1a and 1b are located upstream (on the distributor section 8 side).
The groove is formed so as to have a shallower depth toward the downstream (toward the die head 7).

The molten resin extruded through the helical grooves 3 and 4 is joined and fused at a portion A in the figure. The melted and laminated molten resin passes through an annular passage formed by the mandrel 1 b and the die ring 2 and passes through the die head 6.
And is pushed out of the die lip 7.

Here, the molten resin introduced into the helical groove 4 is a polyolefin resin constituting the mother tube, and the molten resin introduced into the helical groove 3 is resistant to permeation of hydrocarbons and / or oxygen constituting the coating layer. A coating layer made of a thermoplastic polymer having resistance to permeation of hydrocarbons and / or oxygen was fused to a mother pipe made of a polyolefin resin without using an adhesive layer. A resin tube is manufactured.

Here, as the thermoplastic polymer constituting the coating layer, a polyolefin resin (b) fusible with the polyolefin resin (a) constituting the mother tube, and a polyolefin resin (b) which can be fused with the polyolefin resin (b). By using a mixture with a resin composition (c) that is incompatible and has a lower hydrocarbon and / or oxygen permeability than the polyolefin-based resin (a), the mixture becomes shallower from upstream to downstream. 3 and is deformed in the circumferential direction by being extruded through the die 3. Further, the gap distance and the gap area formed by the mandrel and die ring at the die lip portion 7 at the tip of the die head 6 are made smaller and pulled down, so that the tube axis direction is reduced. And as a result, the resin composition (c) becomes a layered body.

The method of manufacturing the resin tube is not limited to the above method. For example, the mother tube is extruded by a straight die, the coating layer is heated again by using a crosshead die. It is also possible to use a method of forming on the outer surface of the mother tube.

[0038]

EXAMPLES Example 1 The main layer was made of a high-density polyethylene HZ7700M for water distribution, MI 0.07 g / 10min (2.16 kgf) (manufactured by Mitsui Chemicals) and a masterbatch resin (manufactured by Toyo Ink) containing a water distribution pigment. Molded with a mixture, and the coating layer is blow-molding grade high molecular weight type high density polyethylene MI 1.9g /
10min (21.6kgf) (Mitsui Chemicals) and a mixture of modified polyethylene and polyamide SELAR RB901 (Mitsui Chemicals)
Was mixed with 10 parts per 100 parts of high-density polyethylene.

The laminated tube was formed by co-extrusion using the die shown in FIG. 1 so that the base tube had a nominal size of 75 (outer diameter 89 mm, thickness 8.65 mm) and the coating layer had a layer thickness of 2 mm.

In the test, pure water was put inside the tube to be evaluated at room temperature, and the outside was immersed in toluene. The amount of toluene in the water was measured by gas chromatography analysis. Was evaluated in mg / l. The evaluation was performed until it was considered that a steady state was reached.

The amount of permeation of toluene in Example 1 was 7 mg / l. In the case where only the main layer was used as a comparative example, the permeation amount of toluene was 85 mg / l, and the effect of the present invention was confirmed.

Example 2 The same main layer as in Example 1 was used, and the coating layer was a blow molding grade high molecular weight type high-density polyethylene MI 1.9 g / 10 min (21.6 kgf);
Polyethylene modified with 0.2% by weight of maleic anhydride and polyamide 6 / polyamide 66 copolymer (Ube Industries, Ltd.)
5033B) and 100 parts of high density polyethylene with 10 parts of copolymer.

The production and test methods are the same as in Example 1. The permeation amount of toluene in Example 2 was 10 mg / l.

Example 3 The main layer was the same as in Example 1, and the coating layer was a blow molding grade high molecular weight type high-density polyethylene MI 1.9 g / 10 min (21.6 kgf);
Polyethylene modified with 0.2% by weight of maleic anhydride and polyacryl nitrile (Mitsui Chemicals "Valex # 1")
000 "), 100 parts of high-density polyethylene, 4 parts of modified polyethylene, 10 parts of polyacrylonitrile
Parts were used.

The production and test were the same as in Example 1. However, the outside of the tube is methyl alcohol 15
What mixed vol% was used. The permeation amount of toluene in Example 3 was 6 mg / l.

Example 4 The main layer was made of polybutene-1P5
050 (manufactured by Mitsui Chemicals) and a masterbatch containing a high concentration of a predetermined pigment for water supply. The coating layer is made of polybutene-1P5050, a maleic anhydride-modified resin of polybutene, and a saponification degree of 32. % Of a copolymer of ethylene and vinyl alcohol, and 10 parts of polymer per 100 parts of polybutene-1.

The main layer is extruded with a straight die so as to have a nominal size of 13 (outer diameter: 17 mm, thickness: 2.2 mm). It covered so that it might be set to 5 mm.

The test is carried out according to the method specified in DIN 4726 to 4729.
I went in. Here, the oxygen transmission rate is g / m ^Two/ day was evaluated.

The laminated tube was formed using the die shown in FIG. 1, and the base tube was co-extruded so that the nominal diameter was 13 (outer diameter 17 mm, thickness 2.2 mm), and the coating layer was 0.5 mm in thickness. .

In Example 4, the amount of oxygen permeation was 0.9 g / m ² / day
Met. In addition, in the case of only the above-mentioned main layer performed as a comparative example, the oxygen permeation amount was 3 g / m ² / day, and the effect of the present invention was confirmed.

[0051]

As described above, according to the present invention, there is provided a resin tube which can sufficiently prevent the permeation of hydrocarbons and / or oxygen and can be manufactured at low cost, and a method for manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a sectional view of a die used for coextrusion molding of a resin tube according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 mandrel 1a, 1b spiral mandrel 2 die ring 3, 4 helical groove 5 radial groove 6 die head 7 die lip 8 distributor section 10 die

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme Court ゛ (Reference) // B29K 23:00 B29K 23:00 B29L 23:00 B29L 23:00 (72) Inventor Masatoshi Kobayashi Tokyo 1-1-2 Marunouchi, Chiyoda-ku Nihon Kokan Co., Ltd. (72) Inventor Akihiko Furuta 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. F-term (reference) 3H111 AA04 BA15 CB23 CC13 DA14 DB03 DB11 EA04 4F100 AK01B AK03A AK03B AK04A AK09A AK27B AK41B AK46B AK69B AL05B AL07B BA02 BA10A BA10B BA15 DA11 EC032 EH20 EH202 EH23 EH232 GB90 JB16B JD02B JD03A AA AA A4A AA A4A AA 4A

Claims (8)

[Claims] The present invention comprises a mother tube made of a polyolefin resin and a coating layer made of a thermoplastic polymer having a resistance to permeation of hydrocarbons and / or oxygen fused to an outer surface of the mother tube without interposing an adhesive layer. A resin tube, characterized in that: 2. The resin pipe according to claim 1, wherein the mother pipe is made of polyethylene or polybutene resin. 3. A polyolefin resin (b) whose coating layer is fusible with the polyolefin resin (a) constituting the mother tube.
And a resin composition (c) that is incompatible with the polyolefin-based resin (b) and has a lower hydrocarbon and / or oxygen permeability than the polyolefin-based resin (a). The resin tube according to claim 1, wherein the article (c) exists in a layered form in the coating layer. 4. A resin composition (c) constituting a part of a coating layer.
4. The resin tube according to claim 3, wherein the resin tube is made of one or more resins selected from a copolymer of ethylene and vinyl alcohol, polyamide, polyester, and polyacrylonitrile. 5. The polyolefin resin (b) constituting a part of the coating layer comprises a modified polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof, or a mixture of the modified polyolefin resin and a polyolefin resin. The resin tube according to claim 3, wherein: 6. After forming a mother tube made of a polyolefin resin, a coating layer made of a thermoplastic polymer having resistance to permeation of hydrocarbons and / or oxygen is melted on the outer surface of the mother tube without interposing an adhesive layer. A method for manufacturing a resin tube, comprising: 7. The base tube and its outside by co-extrusion molding a polyolefin resin to form the base tube and a thermoplastic polymer having resistance to permeation of hydrocarbons and / or oxygen to form the coating layer. A method for manufacturing a resin tube, comprising: manufacturing a resin tube having a coating layer fused to the resin tube without an interposition of an adhesive layer. 8. A die used for co-extrusion molding has a spiral mandrel, and a helical groove formed on an outer periphery of the spiral mandrel is formed such that a depth of the groove decreases from upstream to downstream. The method for manufacturing a resin tube according to claim 7, wherein: