JP2007283582A - Multilayered resin pipe for feeding hydrogen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipe for feeding hydrogen which has a hydrogen-barrier functionality high enough for feeding a gas or liquid mainly composed of hydrogen, a mechanical strength sufficient for the pipe and is used for various purposes. <P>SOLUTION: The pipe for feeding hydrogen is a multilayered resin pipe comprising at least five layers composed of a polyolefin layer (a1: outer layer)/an adhesive layer (b)/a gas barrier layer (c)/an adhesive layer (b)/and a polyolefin layer (a2: inner layer) and has a hydrogen permeability of ≤4 cc/m day atm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hydrogen supply multilayer resin pipe having both hydrogen gas barrier properties and mechanical strength as a molded body.

Multi-layer resin pipes are lightweight and have few seams, so there is no risk of leakage at welds. Instead of metal pipes, they are used as circulating pipes for hot and hot water such as floor heating and central heating. Widely used. For example, polyolefin pipes such as cross-linked polyethylene, polypropylene, and polybutene, and laminated pipes of them with a gas barrier resin such as EVOH are used. (See Patent Document 1 and Patent Document 2)
On the other hand, the use of hydrogen gas has attracted attention due to the energy situation and environmental problems. Since hydrogen gas has problems in handling, infrastructure development is necessary and its research is widely conducted. Initially, metal pipes have been studied mainly due to the explosion risks inherent in hydrogen gas, but in recent years, special resins have been developed for multilayer rubber pipes with metal layers and infrastructure equipment for hydrogen supply. Yes. (Refer to Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6) However, these technologies still have problems in the corrosion of the metal layer, the strength as a tube, and the versatility of the resin. There is a need for a hydrogen supply pipe that does not require any use conditions.
JP-A-61-83035 JP-A-8-224836 JP 2002-168377 A JP 2004-190738 A JP-A-2005-214287 JP 2005-126652 A

  It has a high hydrogen gas barrier property necessary for supplying hydrogen gas or a gas containing hydrogen gas as a main component, which has not been achieved by the currently known technology, and has sufficient mechanical strength as a pipe, and An object of the present invention is to provide a hydrogen supply pipe that can be used under any conditions.

  As a result of intensive studies, the present inventors have surprisingly found that a specific multilayer resin tube can solve the above problems as a hydrogen supply tube, and have completed the present invention.

That is, the present invention
[1] A multilayer resin pipe comprising at least five layers comprising a polyolefin layer (a1: outer layer) / adhesive layer (b) / gas barrier layer (c) / adhesive layer (b) / polyolefin layer (a2: inner layer). And the hydrogen permeation amount of the multilayer resin tube is 1000 cc / m ² · day · atm or less,
[2] The multilayer resin pipe for supplying hydrogen according to [1], wherein the gas barrier layer (c) is EVOH,
[3] The multilayer resin pipe for hydrogen supply according to [1] or [2], wherein the polyolefin layer (a1) and / or the polyolefin layer (a2) is any one of crosslinked polyethylene, non-crosslinked polyethylene and polybutene. ,
[4] The multilayer resin pipe for hydrogen supply according to [3], wherein the polyolefin layer (a1) is a crosslinked polyethylene or polybutene, and non-crosslinked polyethylene is further laminated on the outside of the polyolefin layer (a1).
[5] The multilayer resin pipe for hydrogen supply according to [3], wherein the polyolefin layer (a2) is a crosslinked polyethylene or polybutene, and non-crosslinked polyethylene is further laminated inside the polyolefin layer (a2),
[6] When the film thickness of the gas barrier layer (c) is 1, the polyolefin layers (a1) and (a2) have a film thickness of 1 or more (however, a1 / a2 is 1 or more), and the adhesive layer (b) The multilayer resin pipe for hydrogen supply according to [1], wherein the film thickness is 0.1 to 1.0, and
[7] A multilayer resin pipe structure for hydrogen supply in which the resin pipes of [1] to [6] are joined by electrofusion bonding using a joint,
Is to provide.

  The multilayer resin pipe for hydrogen supply of the present invention has an extremely excellent hydrogen gas barrier property, is excellent in mechanical strength and versatility as a pipe, and is extremely useful as an infrastructure member for hydrogen gas supply. In addition, when non-crosslinked polyethylene is used for the outermost layer of the resin tube, electrofusion bonding is possible, and gas leakage from a joint where gas leakage is likely to occur can be prevented, which is particularly useful. Furthermore, under certain conditions of use, wear resistance and underground use can withstand earth pressure and loads from the ground, and functional deterioration due to corrosive components such as moisture and hydrogen sulfide in the soil is negligible. It is small and has excellent durability when used on the ground because it is so small that functional deterioration due to ultraviolet rays, moisture, and other atmospheric components can be ignored.

<Polyolefin layer>
The type of resin is not particularly limited as long as the polyolefin layer of the present invention is a polyolefin capable of forming a tube, but polybutene, crosslinked polyolefin, and non-crosslinked polyethylene are preferable. As polybutene, it is possible to use one or more of homopolymers of polybutene-1 and polymers obtained by copolymerizing butene-1 as a main component and other olefin monomers as minor components in the main chain. it can. Examples of other monomers used in the butene-1 copolymer include olefins such as ethylene and propylene, diene olefins such as butadiene, and unsaturated carboxylic acid anhydrides such as maleic anhydride. In addition, thermoplastic elastomers such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer elastomer, and polyisobutylene rubber may be mixed within a range that does not impair the object of the present invention.

Examples of the crosslinked polyolefin include water-crosslinked polyolefin, radiation-crosslinked polyolefin, and peroxide-crosslinked polyolefin. A water-crosslinked polyolefin is obtained by copolymerizing a water-crosslinkable polyolefin obtained by copolymerizing a vinyl monomer having a hydrolyzable silyl group with an olefin or graft-polymerizing it with a polyolefin in the presence of a silanol condensation catalyst. It is obtained by crosslinking using hot water, water vapor or the like. Although the silyl group-containing vinyl monomer having a hydrolyzable organic group used for the production of the water-crosslinked polyolefin is not particularly limited, for example, the following general formula:
R-Si- (OR ') ₃
[Wherein, R represents CH ₂ ═CH— or CH═C (CH ₃ ) —COO— (CH ₂ ) _n — (n is an integer of 1 to 5), R ′ represents a methyl group, an ethyl group, CH ₃ — O—CH ₂ —CH ₂ — etc. are shown]
And vinyl monomers represented by The base polyolefin is not particularly limited, but polyethylene is most preferable. The degree of crosslinking of the water-crosslinked polyolefin is preferably 55% or more. Further, an unmodified polyolefin may be blended within a range not impairing the object of the present invention, and in that case, it is desirable that the final degree of crosslinking is 55% or more.

  Examples of radiation-crosslinked polyolefin include polyethylene, polypropylene, ethylene and / or propylene as main components, and other olefins such as butene, diolefin, and one or two unsaturated carboxylic acid anhydrides such as maleic anhydride. A copolymer obtained by copolymerizing the above; and one or more of unsaturated carboxylic acid anhydrides such as other olefins such as butene, diolefins, and maleic anhydrides on a trunk polymer composed of ethylene and / or propylene Polyolefins comprising one or more graft copolymers obtained by graft polymerization of these, or other thermoplastic polymers, ethylene-vinyl acetate copolymers, ethylene-propylene elastomers, polyisobutylenes if necessary. Thermoplastic elastomers such as rubber are used in the present invention. Those included in an amount within the range of interest is not inhibited, polyolefin cross-linked with radiation is preferably used. In this case, ionizing radiation such as γ-rays, β-rays, electron beams, and X-rays is preferably used, and the radiation dose is preferably about 5 to 20 Mrad.

  The peroxide-crosslinked polyolefin can be obtained by reacting with a polyolefin in a polymerization tank or an extruder using a peroxide, particularly an organic peroxide. Specific examples of the peroxide include ketone peroxide, diacyl peroxide, hydroperoxide, dialkyl peroxide, and alkyl perester.

  Polybutene and crosslinked polyolefin are applied to the outer layer (a1) and / or the inner layer (a2). In addition, when non-crosslinked polyethylene is applied to either the outer layer (a1) or the inner layer (a2), it is applied to the other layer.

  In addition, the use of non-crosslinked polyethylene as the polyolefin layer is essential when the multilayer resin pipe of the present invention is electrofused. In the case of the main pipe, it is adopted as the outer layer (a1), and in the case of the joint, it is adopted as the inner layer (a2). The polyethylene used is preferably a polyethylene having an MFR of 0.01 to 10 g / 10 min and a density of 0.910 to 0.980 at 190 ° C. under a load of 2.16 kg. In addition, when using as a main pipe and polybutene or a crosslinked polyethylene is employ | adopted for the outer layer (a1), in order to enable electrofusion joining, you may provide a non-crosslinked polyethylene layer in the outer side of an outer layer.

  The polyolefin layer may contain additives such as an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a colorant, and a filler to the extent that the effects of the present invention are not impaired. For example, as an antioxidant, 2,5-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4′-thiobis- (6-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), octadecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis- (6-t-butylphenol), etc .; Examples of ultraviolet absorbers include ethylene 2-cyano-3,3'-diphenyl acrylate, 2- (2'-hydroxy-5 ' -Methylphenyl) benzotrizol, 2- (2'hydroxy-3'-t-butyl-5'-methylphenyl) 5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2 ' -Dihydroxy-4-methoxy Benzophenone, 2-hydroxy-4-oxybenzobenzophenone, etc .; antistatic agents such as pentaerythrit monostearate, sorbitan monopalmitate, sulfated polyolefins, polyethylene oxide, carbowax, etc .; Is ethylene bisstearoamide, butyl stearate, etc .; carbon black, phthalocyanine, quinacridone, indoline, azo pigments, bengara, etc. as colorants; glass fiber, carbon fiber, ballastite as filler And calcium silicate. Since ultraviolet rays affect the life of the resin tube and the quality of the hydrogen-containing fluid to be supplied, it is particularly useful to add an ultraviolet absorber or an inorganic filler with high ultraviolet shielding properties to the polyolefin layer used for the outer layer (a1). is there.

<Adhesive layer (b)>
The adhesive layer (b) of the present invention is not particularly limited as long as it is an adhesive capable of firmly bonding the polyolefin layer (a) and the gas barrier layer (c), but is graft-modified with an unsaturated carboxylic acid or a derivative thereof. It is preferable to use polyolefin. The polyolefin to be modified is not particularly limited, but polyethylene, ethylene / α-olefin copolymer (α-olefin: 3 to 12 carbon atoms), and polypropylene are preferable. As the graft monomer, an unsaturated carboxylic acid and / or a derivative thereof can be preferably used. Examples of unsaturated carboxylic acids and / or derivatives thereof used as graft monomers include unsaturated compounds having one or more carboxylic acid groups, esters of compounds having carboxylic acid groups and alkyl alcohols, and unsaturated compounds having one or more carboxylic anhydride groups. Examples of the unsaturated group include a vinyl group, vinylene group, and unsaturated cyclic hydrocarbon group. Specific examples of the compound include acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acid [trademark] (endocis-bicyclo [2.2.1] hept Unsaturated carboxylic acids such as -5-ene-2,3-dicarboxylic acid); or derivatives thereof such as acid halides, amides, imides, anhydrides, esters and the like. Specific examples of such derivatives include maleenyl chloride, maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, trimellitic acid, glycidyl maleate and the like. These unsaturated carboxylic acids and / or derivatives thereof can be used singly or in combination of two or more. Of these, unsaturated dicarboxylic acids or acid anhydrides thereof are suitable, and maleic acid, nadic acid or acid anhydrides thereof are particularly preferably used. These may further be grafted with a compound (for example, carbodiimide) for improving the adhesive strength.

  The content of unsaturated carboxylic acid and / or derivative thereof with respect to 100% by weight of the modified polyolefin is usually 0.001 to 5% by weight, preferably 0.01 to 3% by weight. When the content of the unsaturated carboxylic acid and / or derivative thereof is in the above range, the polyolefin composition of the present invention exhibits high adhesive strength with respect to polyester or ethylene / vinyl alcohol copolymer. The content of the unsaturated carboxylic acid and / or derivative thereof can be easily controlled by, for example, appropriately selecting the grafting conditions.

  The method for grafting a graft monomer selected from an unsaturated carboxylic acid and / or a derivative thereof is not particularly limited, and conventionally known graft polymerization methods such as a solution method and a melt-kneading method can be employed. For example, there are a method in which a polymer is melted and a grafting monomer is added thereto for a grafting reaction, or a solution is prepared by dissolving the polymer in a solvent and a grafting monomer is added thereto for a grafting reaction.

  In the adhesive layer (b) of the present invention, other thermoplastic resins, elastomers and the like can be blended within a range that does not impair the properties of the graft-modified product. Their blending may be in the graft modification step or after modification.

  Furthermore, it is also possible to add a known process stabilizer, heat stabilizer, heat aging agent, filler and the like to the adhesive layer (b) of the present invention as long as the properties of the graft-modified product are not impaired. In particular, it is preferable to add a so-called tackifier for the purpose of imparting tackiness. Examples of the substance that imparts tackiness include rosin derivatives, terpene resins, petroleum resins, and hydrides thereof. Among these, hydrogenated terpene resins and hydrogenated petroleum resins are preferable. The tackifier is preferably blended in a proportion of 70 to 95% by weight of the graft modified product and 5 to 30% by weight of the tackifier.

  The adhesive constituting the adhesive layer (b) of the present invention has an MFR of 0.5 to 10 g / 10 min, a density of 0.880 to 0.940, an M value of 0.1 at 190 ° C. under a load of 2.16 kg. It is preferable that it is 01-5.

<Gas barrier layer (c)>
The gas barrier layer (c) in this invention will not be specifically limited if it is resin excellent in the shielding property of hydrogen gas. Examples thereof include ethylene-vinyl alcohol copolymer, vinylidene chloride, polyacrylonitrile, polyvinyl alcohol, polyamide, polyester, and modified products thereof. These may be used alone or in combination of two or more. A particularly preferable resin is a saponified ethylene-vinyl alcohol copolymer (hereinafter abbreviated as EVOH). The ethylene content of EVOH is preferably 20 to 70 mol%, more preferably 22 to 65 mol%, and the saponification degree of the vinyl ester component is preferably 90% or more, and more preferably 95% or more. A typical vinyl ester is vinyl acetate, but other fatty acid vinyl esters (such as vinyl propionate and vinyl pivalate) can also be used.

  In addition, when EVOH contains 0.0002 to 0.2 mol% of a vinylsilane compound as a copolymer component, not only can a homogeneous co-extruded molded product be produced, but also the dispersibility when EVOH is blended with each other is improved. It is useful. Examples of the vinylsilane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane, and γ-methacryloxypropylmethoxysilane. Of these, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used. Further, other comonomer [for example, propylene, butylene, unsaturated carboxylic acid or ester thereof {(meth) acrylic acid, methyl (meth) acrylate ester, ethyl}, etc.) within the range in which the object of the present invention is not inhibited. ], And vinyl pyrrolidone (N-vinyl pyrrolidone etc.) can also be blended.

  EVOH further includes a small amount of α-olefin such as propylene, isobutene, 4-methylpentene-1, hexene and octene, unsaturated carboxylic acid such as itaconic acid, methacrylic acid, acrylic acid and maleic anhydride, and salts thereof. , Its partial or complete ester, its nitrile, its amide, its anhydride, vinylsilane compounds such as vinyltrimethoxysilane, unsaturated sulfonic acid, its salts, alkylthiols, and copolymerization components such as N-vinylpyrrolidone You may go out.

  EVFR used as the gas barrier layer (c) has an MFR under 190 ° C. and a load of 2.16 kg, preferably 0.1 to 50 g / 10 min, and most preferably 0.5 to 20 g / 10 min.

  The EVOH used for the gas barrier layer may be a mixture of two or more types of EVOH having different ethylene contents, or may be a mixture of two or more types of EVOH having different degrees of polymerization or degree of polymerization. Further, both the ethylene content and the degree of polymerization or the degree of saponification may be different.

  When EVOH is used for the gas barrier layer (c), an antioxidant, a colorant, an organic ultraviolet absorber, a lubricant, an antistatic agent, a plasticizer, a cross-linking agent such as boric acid, a filler, and the like, as long as the present invention is not inhibited. Various additives such as inorganic desiccant, and various resins such as polyolefin, polyester, and polyamide may be blended. In particular, since ultraviolet rays affect the life of the resin tube and the quality of the hydrogen-containing fluid to be supplied, it is desirable to add an ultraviolet absorber or an inorganic filler having a high ultraviolet shielding property.

  The gas barrier layer (c) may be a multilayer body. The multilayer body may be subjected to a crosslinking treatment with various aldehydes including boric acid and formalin. Further, a metal such as aluminum, aluminum oxide, or silicon oxide and a metal oxide may be deposited on the surface.

<Multilayer resin pipe>
The layer structure of the multilayer resin pipe of the present invention is at least 5 of polyolefin layer (a1: outer layer) / adhesive layer (b) / gas barrier layer (c) / adhesive layer (b) / polyolefin layer (a2: inner layer). A multilayer resin tube containing layers. Preferred five-layer structure is crosslinked polyolefin or polybutene layer / graft modified polyolefin layer / EVOH layer / graft modified polyolefin layer / crosslinked polyolefin or polybutene layer, more preferably water crosslinked polyolefin layer / graft modified polyethylene layer / EVOH layer / Graft-modified polyethylene layer / water-crosslinked polyethylene layer, more preferably water-crosslinked polyethylene layer / maleic anhydride-modified polyethylene layer / EVOH layer / maleic anhydride-modified polyethylene layer / water-crosslinked polyethylene layer.

  When joining the multilayer resin pipe of the present invention by electrofusion, it is essential to apply non-crosslinked polyethylene as the polyolefin layer. In the case of the main pipe, non-crosslinked polyethylene layer / maleic anhydride modified polyethylene layer / EVOH layer / Maleic anhydride-modified polyethylene layer / water-crosslinked polyethylene layer is the most preferred 5-layer structure. Further, when the polyolefin layer is a crosslinked polyolefin or polybutene, electrofusion bonding can be performed by employing non-crosslinked polyethylene on the outside (or inside) thereof.

  In addition, in the multilayer resin pipe as described above, a surface protective layer may be further provided on the resin layer constituting the outermost layer as necessary. The material for the surface protective layer is preferably a durable polymer such as polyester, vinyl chloride resin, polyolefin, polystyrene, polyamide. They may be laminated using an adhesive. The shape may be any shape such as a film shape, a woven fabric shape, a knitted fabric shape, an unemployed cloth shape, or may be in a state impregnated with another resin. Although the thickness of a surface protective layer is not specifically limited, About 10-100 micrometers is preferable.

  It does not specifically limit as a manufacturing method of the multilayer resin tube of this invention, Arbitrary methods are employable. For example, a method in which the inner layer pipe is melt-extruded, the next layer is melt-extruded on the outer surface, and the like is sequentially formed (in the case of a layer containing a crosslinked polyolefin, a cross-linking treatment is optionally performed after the extrusion). And a coextrusion method (in the case where there is a layer containing a cross-linked polyolefin, a cross-linking treatment is performed after the co-extrusion. When a cross-linked polyolefin having a different cross-linking method is included, a cross-linking treatment is sequentially performed). Can be mentioned. In particular, the coextrusion method is economical and convenient.

In the present invention, the hydrogen permeation amount of the multilayer resin tube is measured as follows.
Nitrogen is charged from the valve C and exhausted from the valve D to replace the inside of the chamber with nitrogen. Hydrogen is charged from the valve B, and the inside of the pipe is replaced with hydrogen. After the valve A is closed, water is injected from the valve C, and the gas in the chamber is sampled into the gas chromatograph through the valve D. (See Figure 1)
The hydrogen permeation amount of the multilayer resin pipe of the present invention is desirably a concentration that is normally in contact with the atmosphere and does not ignite even when naturally mixed. Specifically, it is 1000 cc / m ² · day · atm or less, preferably 500 cc / m. ² · day · atm or less, more preferably 200 cc / m ² · day · atm or less.

  When the multilayer resin pipe of the present invention is used for hydrogen supply, the strength of the pipe is important in view of the danger of the gas handled. The necessary mechanical properties are 10 MPa or more, preferably 15 MPa or more as the tensile yield stress, 20 MPa or more as the tensile break stress, and 300% or more, preferably 400% or more, as the elongation at break.

  The outer diameter, inner diameter, and thickness of the multilayer resin pipe of the present invention can be appropriately selected according to the resin constituting each layer and the application scene, but the outer diameter is, for example, about 10 to 100 mm, The inner diameter is, for example, about 5 to 95 mm. The wall thickness is, for example, about 5 to 20 mm. Regarding the five basic layers, the film thickness of the polyolefin layers (a1) and (a2) when the film thickness of the gas barrier layer (c) is 1 is 1 or more and a1 / a2 is 1 or more Is preferred. Since the main purpose of each layer is different such that the inner layer has a barrier property of impurities (for example, water) in the pipe gas, and the outer layer has strength against external impacts, etc., such a film thickness ratio is used. It is desirable. Further, when a1 / a2 is 1 or more, the resin used is minimized, and the thickness of the tube can be increased. In that case, as a1, for example, 1-1000 are preferable, More preferably, it is 1-800, More preferably, it is 1-500. On the other hand, as a2, Preferably it is 1-100, More preferably, it is 1-50, More preferably, it is 1-30. The film thickness of the adhesive layer (b) is preferably 0.1 to 1.0, more preferably 0.3 to 0.8. The film thickness (absolute value) of the gas barrier layer (c) varies depending on the tube diameter and the resin to be used. For example, when EVOH is used, it is 1 to 500 μm, preferably 10 to 300 μm. However, all of these numerical values need to be adjusted so as to satisfy the hydrogen permeation amount and the mechanical properties.

  The multilayer resin tube of the present invention may have any shape as long as the inside is hollow, and examples thereof include a simple cylindrical straight tube, a manifold such as an L-shaped tube and a T-shaped tube. The length is not particularly limited, and a joint for joining is also included in the multilayer resin pipe of the present invention.

<Multilayer resin pipe structure>
Of the multilayer resin pipes of the present invention, those that can be electrofused can be formed into a structure via a joint by a conventionally known method. In addition to its own hydrogen gas barrier property, the structure using the multilayer resin pipe of the present invention can also reduce gas leakage from the connecting portion where gas leakage is likely to occur compared to mechanical fastening, etc. Very useful.

  The joint used for the electric fusion bonding may be a conventionally known non-crosslinked polyethylene single layer, or a two-layered one in which the inner layer is non-crosslinked polyethylene and the outer layer is crosslinked polyethylene. A multi-layer joint having a symmetric layer structure may be used. Electrofusion can be performed by a known method.

The hydrogen permeation amount of the multi-layer resin pipe structure bonded by electrofusion is 1000 cc / m ² · day · atm or less, preferably 500 cc / m ² · day · atm or less, per 1 m of the structure including one joint. Preferably, it is 200 cc / m ² · day · atm or less.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereby.

<Use resin>
Polyethylene A: Silane-crosslinked polyethylene
MFR (190 ° C., 2.16 kg load): 0.2 g / 10 min
Density: 0.939
Polyethylene B: Medium density polyethylene (non-crosslinked)
MFR (190 ° C., 2.16 kg load): 0.2 g / 10 min
Density: 0.939
Adhesive: Maleic anhydride-modified polyethylene
MFR (190 ° C., 2.16 kg load): 1.8 g / 10 min
Density: 0.916
EVOH: MFR (190 ° C., 2.16 kg load): 1.6 g / 10 min
Density: 1.19
Ethylene content: 32%

<Method for measuring physical properties>
[Hydrogen permeation]
Nitrogen is charged from the valve C and exhausted from the valve D to replace the inside of the chamber with nitrogen. Hydrogen is charged from the valve B, and the inside of the pipe is replaced with hydrogen. After the valve A is closed, water is injected from the valve C, and the gas in the chamber is sampled into the gas chromatograph through the valve D. (See Figure 1)
[Tensile yield stress]
[Tensile breaking stress]
[Elongation at tensile break]
The measurement was performed according to JIS K 6769.

[Example 1]
Three types and five layers were coextruded so that the outermost layer and innermost layer were polyethylene A, the second layer and the fourth layer were adhesive, and the third layer was EVOH, followed by crosslinking treatment to form a five-layer resin tube. . The outer diameter was 13 mm, the inner diameter was 9.8 mm, and the thickness of each layer was 750/50/100/50/550 (μm). Each characteristic of the obtained five-layer resin pipe was as follows.
Hydrogen permeation amount: 63.9 cc / m ² · day · atm
Tensile yield stress: 15.3 MPa
Tensile stress at break: 23.1 MPa
Tensile elongation at break: 410%

[Example 2]
A 5-layer resin board was prepared in the same manner as in Example 1 except that polyethylene B was used for the outermost layer. The five-layer resin pipes were fusion-bonded with an electric fusion-type socket using a non-crosslinked polyethylene single-layer joint. As a result of measuring the hydrogen permeation amount of the fusion bonded resin pipe, it was 88.9 cc / m ² · day · atm.

[Comparative Example 1]
Polyethylene A was used to extrude a single layer resin tube. The outer diameter, inner diameter, and thickness of the tube were combined with Example 1. The hydrogen permeation amount of the pipe was 1730 cc / m ² · day · atm.

[Comparative Example 2]
The resin pipe obtained in Example 1 was used, and the pipe was joined with an existing mechanical joint. The hydrogen permeation amount of the bonded tube was measured but could not be measured due to leakage.

    The multilayer resin pipe and multilayer resin pipe structure of the present invention are particularly suitable as infrastructure pipes for hydrogen supply because they are excellent in workability and durability, and have excellent hydrogen gas barrier properties and mechanical properties as pipes. .

It is the schematic of the apparatus which measures the hydrogen permeation amount of the multilayer resin pipe and multilayer resin pipe structure of the present invention.

Claims (7)

A multilayer resin pipe comprising at least five layers comprising a polyolefin layer (a1: outer layer) / adhesive layer (b) / gas barrier layer (c) / adhesive layer (b) / polyolefin layer (a2: inner layer), A multilayer resin pipe for supplying hydrogen, wherein the hydrogen permeation amount of the multilayer resin pipe is 1000 cc / m ² · day · atm or less. The multilayer resin pipe for hydrogen supply according to claim 1, wherein the gas barrier layer (c) is EVOH. The multilayer resin pipe for hydrogen supply according to claim 1 or 2, wherein the polyolefin layer (a1) and / or the polyolefin layer (a2) is any one of crosslinked polyethylene, non-crosslinked polyethylene, and polybutene. The multilayer resin pipe for hydrogen supply according to claim 3, wherein the polyolefin layer (a1) is a crosslinked polyethylene or polybutene, and non-crosslinked polyethylene is further laminated on the outside of the polyolefin layer (a1). The multilayer resin pipe for hydrogen supply according to claim 3, wherein the polyolefin layer (a2) is a crosslinked polyethylene or polybutene, and non-crosslinked polyethylene is further laminated inside the polyolefin layer (a2). When the film thickness of the gas barrier layer (c) is 1, the polyolefin layers (a1) and (a2) have a film thickness of 1 or more (however, a1 / a2 is 1 or more), and the adhesive layer (b) has a film thickness of It is 0.1-1.0, The multilayer resin tube for hydrogen supply of Claim 1 characterized by the above-mentioned. A multilayer resin pipe structure for supplying hydrogen, wherein the resin pipes according to claim 1 are joined by electrofusion bonding using a joint.

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