JP5818349B2 - High pressure gas transfer hose - Google Patents

Description

  The present invention relates to a high-pressure gas transfer hose such as high-pressure hydrogen, and more particularly to a high-pressure gas transfer hose such as a hydrogen gas supply hose used to supply hydrogen gas to an automobile fuel cell.

  Conventionally, metal pipes have been mainly studied as a hose for supplying hydrogen gas from a hydrogen gas station to a fuel cell. However, metal pipes are not flexible and handleability is troublesome. Since there is a problem of hydrogen embrittlement, development of rubber or resin hoses has been promoted in recent years. When a rubber or resin hose is used, a hose having a multilayer structure in which a gas barrier layer, a reinforcing layer, etc. are laminated is generally used so that hydrogen gas does not leak out and ensures durability.

  Here, as the gas barrier layer, for example, in Japanese Unexamined Patent Application Publication No. 2007-15279 (Patent Document 1) and Japanese Unexamined Patent Application Publication No. 2009-19717 (Patent Document 2), an ethylene / vinyl alcohol copolymer (EVOH resin) layer is used. It is used. As the hose, a water-resistant olefin-based resin or polyethylene terephthalate-based resin is used for the inner surface layer, and a sheet in which organic fibers or metal wires are braided is used as a reinforcing layer. .

  Japanese Patent Laid-Open No. 2006-168358 (Patent Document 3) discloses a multilayer tube for hydrogen transfer including an inner layer made of a fluorine-based polymer, a gas barrier layer made of EVOH resin, and an outer layer made of polyamide.

  As for a high-pressure hose for a liquefied propane gas supply facility, Japanese Patent Application Laid-Open No. 2007-218338 (Patent Document 4) uses a gas barrier layer made of polyamide resin and a spiral of organic fiber or metal wire as a reinforcing layer. A high-pressure hose using a vulcanized rubber layer on the inner surface is disclosed in order to use the layer and give the hose itself flexibility.

Japanese Patent Laid-Open No. 2010-31993 (Patent Document 5) discloses a heat in which the gas permeability coefficient of dry hydrogen gas at 90 ° C. is 1 × 10 ⁻⁸ cc · cm / cm ² · sec · cmHg or less on the inner surface layer. A material using a blade structure in which a plastic resin is used and a polyparaphenylene benzbisoxazole (PBO) fiber is braided as a reinforcing layer has been proposed. Here, specific examples of the thermoplastic resin used as the gas barrier layer include nylon, polyacetal, and EVOH resin (paragraph number 0011). In the examples, nylon is used. It is described that by forming the reinforcing layer with PBO fibers, hydrogen embrittlement can be avoided and an internal pressure of about 70 to 80 MPa can be withstood (paragraph number 0021).

Japanese Unexamined Patent Publication No. 2007-15279 JP 2009-19717 A JP 2006-168358 A JP 2007-218338 A JP 2010-31993 A

As described above, by providing a multi-layer structure in which a gas barrier layer, a reinforcing layer, and the like are combined, flexibility and gas barrier properties are imparted, but the hydrogen barrier properties of the gas barrier layer can be further improved for the following reasons. It has been demanded.
Since hydrogen has a smaller molecular size than oxygen, it is easy to dissolve and penetrate into the resin layer. In recent years, hoses used for supplying hydrogen gas to in-vehicle fuel cells have a high-pressure ( 35 to 80 MPa) of hydrogen gas is transferred and filled. For this reason, the high-pressure hydrogen gas supply hose is required to have a high gas barrier property against high-pressure hydrogen and low hydrogen solubility.

  Furthermore, when the high pressure hydrogen gas supply hose is not in use, the hydrogen gas dissolved in the resin layer expands when the pressure is returned from the high pressure to the normal pressure in the hose (at the time of depressurization), and blisters and cracks occur. In some cases, durability against repeated high-pressure gas supply and depressurization is also required.

  The present invention has been made in view of such circumstances, and the object of the present invention is to have a high gas barrier property and low hydrogen solubility, and further against changes accompanying the supply and stop of high-pressure gas. An object of the present invention is to provide a high-pressure gas transfer hose having excellent durability.

The present inventors tried various studies to use a polyamide resin conventionally used for a gas barrier layer and a PVA resin known as a resin having a higher gas barrier property than an EVOH resin as a raw material of the gas barrier layer. It was.
Since PVA resin is usually difficult to melt-mold, and is hard, flexible, and poor in elongation, it is necessary to solve these problems in order to use it as a constituent material of a hose. With the knowledge that the melt-formability can be solved by using a PVA resin having a specific structure, the PVA resin having this specific structure is used, and the elongation and flexibility have some gas barrier properties. However, the inventors reached the idea that the problem can be solved by mixing a polyamide resin that is excellent in elongation and flexibility, and proceeded with studies. However, it has been found that the generation of cracks and blisters associated with repeated cycles of high-pressure gas supply / stop (depressurization) cannot be solved simply by improving the gas barrier property in the sense that the gas is difficult to permeate.

Then, the present inventors arrived at this invention as a result of a further examination about the resin composition containing PVA-type resin and polyamide resin of a specific structure.
That is, the hose for high-pressure gas transfer of the present invention includes a polyvinyl alcohol resin (A) containing a structural unit represented by the following general formula (1), and a polyamide resin (B) having a solubility parameter of 22 to 28 MPa ^1/2. At least one layer made of a resin composition.

〔式中、Ｒ^１〜Ｒ^６はそれぞれ独立して水素原子又は有機基を表し、Ｘは単結合又は結合鎖を示す〕

[Wherein R ^{1 to} R ⁶ each independently represents a hydrogen atom or an organic group, and X represents a single bond or a bond chain]

The content weight ratio (A / B) of the polyvinyl alcohol resin (A) and the polyamide resin (B) is preferably 90/10 to 75/25, and the melt viscosity of the polyamide resin (B) is 200. It is preferably ˜2500 Pa · sec.
Moreover, it is preferable that the content rate of the said General formula (1) in the said polyvinyl alcohol-type resin (A) is 2-15 mol%.

The polyvinyl alcohol-based resin (A) has a content of structural units other than the structural unit represented by the formula (1) and a structural unit derived from a saponified vinyl ester monomer, of 50 mol% or less. Is preferred. Furthermore, it is preferable that the layer made of the resin composition is an inner layer.
The high-pressure gas transfer hose of the present invention is suitable as a hydrogen gas transfer hose.

  Here, the solubility parameter (SP value) refers to the square root of the cohesive energy density of molecules, and is usually used as an index of organic solvent resistance of plastic materials.

  By using a side chain 1,2-diol-containing polyvinyl alcohol-based resin, while maintaining the original excellent gas barrier property of polyvinyl alcohol and extremely low hydrogen solubility (4-10 ppm) under high pressure hydrogen of 35-80 MPa, It becomes possible to perform melt molding, and further, by using a specific polyamide resin, it is possible to suppress the occurrence of blisters in the gas barrier layer and the deterioration of the mechanical characteristics even under repeated supply of high-pressure hydrogen gas and depressurization.

It is a schematic diagram for demonstrating the structure of the hydrogen permeability measuring apparatus used in the Example. It is a figure which shows the structure of the test piece used in the Example. In an Example, it is a schematic diagram which shows the structure of the apparatus used for the high pressure hydrogen exposure test. It is a figure which shows the pressure pattern of a high pressure hydrogen gas exposure-depressurization cycle test.

The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and is not limited to these contents.
First, the resin composition as a raw material for the gas barrier layer of the high-pressure gas transfer hose of the present invention will be described.

<Resin composition for gas barrier layer>
The gas barrier layer of the hose of the present invention is composed of the following resin composition. The resin composition is a resin composition containing a polyvinyl alcohol resin (A) having a specific structure and a polyamide resin (B) having a solubility parameter of 22 to 28 MPa ^1/2 .

[(A) PVA resin]
The polyvinyl alcohol (PVA) resin having the specific structure is a polyvinyl alcohol having a side chain 1,2-diol unit represented by the following general formula (1) (hereinafter referred to as “side chain 1,2-diol-containing PVA”). ) System resin.

In the general formula (1), R ^{1 to} R ⁶ each independently represent a hydrogen atom or an organic group. R ^{1 to} R ⁶ are preferably all hydrogen atoms, but may be organic groups as long as the resin properties are not significantly impaired. Although it does not specifically limit as this organic group, For example, C1-C4 alkyl groups, such as a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, are preferable, You may have substituents, such as a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, and a sulfonic acid group, as needed.

In the general formula (1), X is a single bond or a linking group, and is preferably a single bond from the viewpoint of improving crystallinity and reducing free volume (intermolecular void) in an amorphous part. The bonding chain is not particularly limited, but other hydrocarbons such as alkylene, alkenylene, alkynylene, phenylene, naphthylene (these hydrocarbons may be substituted with halogen such as fluorine, chlorine, bromine, etc.) _{, -O -, - (CH 2} O) m -, - (OCH 2) m -, - (CH 2 O) mCH 2 -, - CO -, - COCO -, - CO (CH 2) mCO -, - _{CO (C 6 H 4) CO} -, - S -, - CS -, - SO -, - SO 2 -, - NR -, - CONR -, - NRCO -, - CSNR -, - NRCS -, - NRNR- _{, -HPO 4 -, - Si (} OR) 2 -, - OSi (OR) 2 -, - OSi (OR) 2 O -, - Ti (OR) 2 -, - OTi (OR) 2 -, - OTi ( _{OR) 2 O -, - Al} (OR) -, - OAl (OR) -, - OAl (O ) Although O- and the like (R is an optional substituent each independently, a hydrogen atom, an alkyl group are preferred, and m is a natural number) and the like. Among these, an alkylene group having 6 or less carbon atoms, particularly a methylene group, or —CH ₂ OCH ₂ — is preferable from the viewpoint of viscosity stability during production, heat resistance, and the like.

In the most preferable structure of the 1,2-diol structural unit represented by the general formula (1), R ^{1 to} R ⁶ are all hydrogen atoms, and X is a single bond. That is, the structural unit represented by the following structural formula (1a) is most preferable.

  Such side chain 1,2-diol-containing PVA resin is not particularly limited, but (i) a method of saponifying a copolymer of a vinyl ester monomer and a compound represented by the following general formula (2), (Ii) a method of saponifying and decarboxylating a copolymer of a vinyl ester monomer and a vinyl ethylene carbonate represented by the following general formula (3), and (iii) a vinyl ester monomer represented by the following general formula (4) The copolymer with 2,2-dialkyl-4-vinyl-1,3-dioxolane can be produced by a method of saponification and deketalization.

(2) In the formulas (3) and (4), R ^{1 to} R ⁶ are the same as those in the formula (1). R ⁷ and R ⁸ are each independently hydrogen or R ⁹ —CO— (wherein R ⁹ is an alkyl group having 1 to 4 carbon atoms). R ¹⁰ and R ¹¹ are each independently a hydrogen atom or an organic group.
For the methods (i), (ii), and (iii), for example, the method described in JP-A-2006-95825 can be employed.

Among them, the method in terms of excellent in copolymerization reactivity and industrial handling (i) are preferred, ^R 1 to R ⁶ are hydrogens, X a single ^bond, R 7, ^{R 8} is ^R 9 -CO- 3,4-diasiloxy-1-butene in which R ⁹ is an alkyl group is preferred, and among these, 3,4-diacetoxy-1-butene in which R ⁹ is a methyl group is particularly preferred.

  Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, versatic. Although vinyl acid acid etc. are mentioned, vinyl acetate is preferably used especially from an economical viewpoint.

  In addition to the above-mentioned monomers (vinyl ester monomers, compounds represented by the general formulas (2) to (4)), a range that does not affect the gas barrier properties (usually 50 mol% or less, preferably 33 mol% or less, More preferably, it is 10 mol% or less that does not affect the amount of hydrogen dissolved under high pressure). As a copolymer component, an α-olefin such as ethylene or propylene; 3-buten-1-ol, 4-pentene- Hydroxyl group-containing α-olefins such as 1-ol; further unsaturated acids such as vinylene carbonates and acrylic acid or salts thereof, mono- or dialkyl esters, nitriles such as acrylonitrile, amides such as methacrylamide, ethylene sulfonic acid , Olefin sulfonic acids such as allyl sulfonic acid and methallyl sulfonic acid or salts thereof. It may be copolymerized. Among these, ethylene that forms a eutectic with a vinyl alcohol structural unit is particularly preferable.

  The polymerization of the vinyl ester monomer and the general formula (2), (3), or (4) can be performed by any known polymerization method such as solution polymerization, suspension polymerization, emulsion polymerization, and the like.

  As the saponification of the obtained copolymer, as a known method and saponification method, a conventionally known saponification method which is a conventional PVA containing no side chain 1,2-diol can be adopted. . That is, it can be carried out using an alkali catalyst or an acid catalyst in a state where the copolymer is dissolved in alcohol or water / alcohol solvent. Examples of the alkali catalyst include alkali metal hydroxides and alcoholates such as potassium hydroxide, sodium hydroxide, sodium methylate, sodium ethylate, potassium methylate, and lithium methylate.

  The reaction temperature of the saponification reaction is preferably 20 ° C to 60 ° C. If the reaction temperature is too low, the reaction rate is reduced and the reaction efficiency is lowered. In addition, when saponifying under high pressure using a pressure tower type continuous saponification tower or the like, saponification can be performed at a higher temperature, for example, 80 to 150 ° C., and a small amount of saponification catalyst can be used for a short time. It is possible to obtain a saponification degree.

  The degree of polymerization in the side chain 1,2-diol-containing PVA resin as described above is usually 250 to 1000, preferably 300 to 650, more preferably 400 to 500. When the degree of polymerization becomes too high, the melt viscosity becomes too high, and a load is applied to the extruder, making it difficult to mold. Further, due to shear heat generation during melt-kneading, the resin temperature may be increased, and the resin may be deteriorated. On the other hand, if the degree of polymerization is too low, the molded product becomes brittle, so that in the gas hose, the gas barrier layer tends to crack, and the hydrogen gas barrier property tends to decrease.

  The saponification degree of the vinyl ester moiety in the side chain 1,2-diol-containing PVA resin is a value measured based on JIS K6726, and is usually 98 to 100 mol%, preferably 99 to 99.9 mol%. More preferably, it is 99.5-99.8 mol%. If the degree of saponification is too low, it means that the content of OH groups is reduced, and the hydrogen gas barrier property tends to be lowered. On the other hand, a highly saponified and completely saponified PVA resin tends to be difficult to produce industrially.

  The content of the structural unit represented by the above formula (1) (side chain 1,2-diol content) is usually 2 to 15 mol%, preferably 4 to 12 mol%, more preferably 5 to 8 mol%. is there. When the content of the side chain 1,2-diol is too high, the glass transition temperature is increased, which is preferable in terms of reducing hydrogen solubility, but the productivity of PVA tends to be reduced. On the other hand, if the side chain 1,2-diol content is too low, the melting point and the decomposition point of the PVA-based resin approach each other, and melt molding becomes difficult. Furthermore, the hydrogen gas barrier property becomes insufficient, and the hydrogen solubility increases.

The side chain 1,2-diol-containing PVA resin as described above tends to be excellent in hydrogen gas barrier property and low hydrogen solubility, in addition to being able to be melt-molded, compared to EVOH resin and unmodified PVA resin. It is in. In general, the side chain 1,2-diol-containing PVA resin is known to have lower crystallinity than unmodified PVA because the side chain 1,2-diol portion disturbs crystallization. From this fact, it is expected that the side chain 1,2-diol-containing PVA is inferior in gas barrier property to that of unmodified PVA. Was found to be contrary to the expectation that side chain 1,2-diol-containing PVA tends to outperform unmodified PVA. This means that in the amorphous part, the presence of primary hydroxyl groups in the side chain 1,2 diol part forms a dense network by hydrogen bonds stronger than normal PVA resin, and the free volume in the amorphous part is reduced. It is thought that it is because it is possible.
Further, preferably, the side chain 1,2-diol-containing PVA has an advantage that it has a low melting point and a low crystallinity and is excellent in melt moldability because the crystal lamella size is smaller than that of the unmodified PVA. .

[(B) Polyamide resin]
The polyamide resin used in the present invention is a resin having an amide bond in the main chain, and is a polyamide resin having an SP value (MPa ^1/2 ) of 22 to 28, preferably 24 to 26. Here, the solubility parameter (SP value) refers to the square root of the cohesive energy density of molecules, and is usually used as an index of organic solvent resistance of plastic materials.

The SP value of the polyamide resin depends on the polyamide structure (constituent monomer unit). The polyamide resin that can be used in the present invention may have an SP value (MPa ^1/2 ) of 22 to 28, and the type, composition, polymerization degree, and the like of the constituent monomers are not particularly limited.
Examples of polyamide resins having an SP value (MPa ^1/2 ) of 22 to 28 include polycapramide (nylon 6, SP value 25.7), polyhexamethylene adipamide (nylon 66, SP value 27.5), caprolactam / Hexamethylenediamine adipate copolymer (nylon 6/66, SP value 25.8 of copolymer with copolymerization ratio 80/20), caprolactam / lauryl lactam copolymer (nylon 6/12, copolymerization ratio 80/20) SP value of the copolymer of 24.4) and the like.

Polyamide resin is inferior in gas barrier properties compared to polyvinyl alcohol resin, but is excellent in flexibility and elongation, and by adding polyamide resin, flexibility and elongation are imparted to polyvinyl alcohol resin. Is considered possible.
On the other hand, the SP value of the side chain 1,2-diol-containing PVA resin varies depending on the polymerization degree, saponification degree, and 1,2-diol content, but is generally about 44 to 47. Therefore, the side chain 1,2-diol-containing PVA resin and the polyamide resin are not compatible as estimated from the difference in SP value, the free energy of mixing acts on the plus side, and the resin is a mixture of both The composition constitutes a sea-island structure using a side chain 1,2-diol-containing PVA resin as a main component as a matrix resin.

Since the polyamide resin having a large SP value generally tends to have a high melting point, the temperature of the melt blending process with the PVA resin has to be increased, and the deterioration of the side chain 1,2-diol-containing PVA resin is caused. Thus, industrial productivity is reduced. On the other hand, if the SP value of the polyamide resin is too small, the difference in SP value from the side chain 1,2-diol-containing PVA resin becomes too large, and the wettability with the side chain 1,2-diol-containing PVA resin is increased. This is because blisters are likely to be generated at the time of depressurization after the supply of high-pressure hydrogen gas, and the durability of the hose is lowered. The occurrence of this blister is a phenomenon that was not seen in the gas barrier layer composed of the PVA resin alone or the polyamide layer composed of the polyamide resin alone, and the gas barrier layer using a mixed resin composition of the polyamide resin and the PVA resin, particularly its This is a phenomenon that occurs in the surface layer. It was also found that this phenomenon can occur even when the hydrogen gas permeation amount and the hydrogen dissolution amount are small. As a result of the study by the present inventors, in the mixed system of the PVA resin and the polyamide resin, when the SP values of both are far apart, not only the dispersibility is lowered, but also at the interface between the PVA resin and the polyamide resin. Probably because the binding (affinity) also becomes moderate, small gas molecules such as hydrogen are likely to enter this interface portion. The once invaded hydrogen gas is less likely to be eliminated based on the gas barrier property of the original PVA resin itself, and remains in the gas barrier layer. It is considered that molecular movement can be performed at the sea-island interface between the resin and the polyamide resin, and expansion (so-called blistering) is likely to occur. On the other hand, by using a polyamide resin having an SP value (MPa ^1/2 ) of 22 to 28, even if the SP value difference becomes small, compatibility cannot be ensured. Absent. However, it is considered that the wettability at the interface of the sea-island structure has been improved, and it has become possible to withstand hydrogen expansion during high-pressure hydrogen depressurization.

The melt viscosity of the polyamide resin used in the present invention at 220 ° C. and a shear rate of 122 sec ⁻¹ is usually 200 to 2500 Pa · s, preferably 500 to 1800 Pa · s, and more preferably 1000 to 1500 Pa · s. If the melt viscosity is too high, the melt-mixability with the PVA resin (A) becomes poor, and the size of the island component (polyamide resin) in the sea-island structure formed by the PVA resin and the polyamide resin becomes too large. If the melt viscosity is too low, the melt-mixability with the PVA resin (A) becomes poor, the homogeneous dispersion of the polyamide resin becomes insufficient, and effects such as imparting flexibility by blending the polyamide resin cannot be sufficiently obtained.

  The polyamide resin is usually 95/5 to 60/40 as the weight ratio (A / B) of the side chain 1,2-diol-containing PVA resin (A) and the polyamide resin (B), preferably 90/10 to 70/30, more preferably 90/10 to 75/25. If the content ratio A / B is too large, that is, if the PVA resin content is too high, durability, bending fatigue resistance and stretchability will be poor. If A / B is too small, that is, if the PVA resin content is small, the hydrogen gas barrier effect by the PVA resin is insufficient.

[(C) Other additives]
The resin composition for a gas barrier layer used in the present invention does not impair the effects of the present invention, if necessary, in addition to the side chain 1,2-diol-containing PVA resin (A) and polyamide resin (B). As long as (for example, less than 5% by weight of the entire resin composition), a polyamide resin having an SP value outside the range of 22 to 28; an unmodified PVA resin not having the structural unit of the general formula (1); Thermoplastic resins; Plasticizers such as aliphatic polyhydric alcohols such as ethylene glycol, glycerin and hexanediol; Saturated aliphatic amides (such as stearic acid amide), unsaturated fatty acid amides (such as oleic acid amide), bis fatty acid amides (For example, ethylene bis stearamide), low molecular weight polyolefin (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10,000, or low molecular weight poly Anti-blocking agent; antioxidant; coloring agent; antistatic agent; ultraviolet absorber; antibacterial agent; insoluble inorganic salt (for example, hydrotalcite); filler (for example, inorganic filler); oxygen Absorbers (for example, ring-opening polymers of cycloalkenes such as polyoctenylene, cyclized products of conjugated diene polymers such as butadiene, etc.); surfactants, waxes; dispersants (eg, monoglycerides of stearic acid), heat stabilizers, Add appropriate additives such as light stabilizer, drying agent, flame retardant, crosslinking agent, curing agent, foaming agent, crystal nucleating agent, anti-fogging agent, biodegradation additive, silane coupling agent, conjugated polyene compound can do.

[Preparation of resin composition for gas barrier layer]
The resin composition for a gas barrier layer is formulated with a predetermined amount of the side chain 1,2-diol-containing PVA resin (A), polyamide resin (B), and an additive (C) added as necessary. It can be prepared by melt-kneading.

  For the melt-kneading, a known kneader such as an extruder, a Banbury mixer, a kneader ruder, a mixing roll, or a blast mill can be used. For example, in the case of an extruder, a single screw or a twin screw extruder may be used. After melt-kneading, a method of extruding the resin composition into a strand shape, cutting and pelletizing can be employed.

  The melt kneading temperature is appropriately selected according to the types of the side chain 1,2-diol-containing PVA resin (A) and polyamide resin (B), but is usually from 215 to 230 ° C, preferably from 220 to 235 ° C. is there.

<High pressure gas transfer hose>
The hose for high-pressure gas transfer of the present invention includes at least one layer composed of the resin composition for the gas barrier layer, and is preferably an inner layer or an intermediate layer, more preferably an intermediate layer, particularly a hose having a multilayer structure. It is included in the intermediate layer from the inner layer. When the gas barrier layer is an intermediate layer, a water-resistant, moisture-impermeable thermoplastic resin layer is preferably used for the innermost hose layer. Moreover, it is preferable to provide a reinforcing layer in the outermost layer or the intermediate layer.

Although the internal diameter of a hose is not specifically limited, Usually, it is about 4.5-12 mm, an outer diameter is about 7-15 mm, and the thickness is set to about 1-10 mm.
The thickness of the gas barrier layer is not particularly limited, but is selected in the range of 5 to 15%, particularly 8 to 12% of the thickness of the hose.

  As the thermoplastic resin used for the moisture-impermeable thermoplastic resin layer, for example, a hydrophobic thermoplastic resin is preferably used. For example, linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, ethylene-α-olefin (carbon number) 4-20 α-olefin) copolymer, ethylene-acrylate copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polybutene, polypentene, and other olefins. Homologous polyolefin resins such as homo- or copolymers, cyclic polyolefins, or homo- or copolymers of these olefins grafted with unsaturated carboxylic acids or esters thereof, polystyrene resins, polyamides, copolymer polyamides, etc. Polyamide resin, polyvinyl chloride, poly salt Vinylidene, acrylic resins, vinyl ester resins such as polyvinyl acetate, polyurethane resins, tetrafluoroethylene, tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymers, ethylene / tetrafluoroethylene copolymers, tetrafluoroethylene / Fluoropolymers such as hexafluoropropylene copolymer, and thermoplastic resins such as chlorinated polyethylene and chlorinated polypropylene.

  As the reinforcing layer, for example, a nonwoven fabric, a cloth, a metal foil, or the like can be used as long as the flexibility and elongation of the hose are not impaired. Preferably, the sheet layer is formed of braided high-strength resin fibers such as polyparaphenylene bisbisoxazole (PBO) fibers and aramid fibers, or a layer formed by winding the sheet in a spiral.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to description of a following example.
In the examples, “part” means a weight basis unless otherwise specified.

[Measurement evaluation method]
First, the measurement evaluation method employed in the following examples will be described.
(1) Hydrogen gas barrier property (hydrogen gas permeation)
A film test piece having a thickness of 20 μm is set in the sample portion of the hydrogen permeability measuring apparatus shown in FIG. 1, and pressurized hydrogen is sent toward the film sample at 41 ° C. and a hydrogen pressure of 0.5 MPa, and the permeated hydrogen is removed. The amount of permeation (cc · 20 μm / m ² · day · atm) was measured.

(2) Tensile elongation at break (%)
Using a dumbbell-shaped test piece having a thickness of 2 mm shown in FIG. 2, the tensile tester was used to extend the length by 30%. When it broke before extending 30%, the elongation at break was taken as the measured value, and when it did not break even after 30% elongation, the measured value was over 30%.

(3) High-pressure hydrogen gas exposure-decompression cycle test (durability)
Using a hydrogen high-pressure gas facility configured as shown in FIG. 3, a dumbbell-shaped test piece having a thickness of 2 mm as shown in FIG. The high pressure hydrogen was exposed for 20 hours, and after standing for 0.5 hours after depressurization, 20 cycles were repeated (total exposure time 400 hours).
After the high-pressure hydrogen gas exposure-depressurization cycle test, the test piece was taken out and the state of the test piece was visually observed. In particular, the presence or absence of blisters (usually generated in the dumbbell portion) was observed.

(Preparation of resin composition)
(1) Side chain 1,2-diol-containing PVA resin (A)
A reaction vessel equipped with a reflux condenser and a stirrer was charged with 68.0 parts of vinyl acetate, 23.8 parts of methanol, and 8.2 parts of 3,4-diacetoxy-butene, and 0.3 mol of azobisisobutyronitrile. % (Vs. vinyl acetate charged) was added and the temperature was raised under a nitrogen stream while stirring to initiate polymerization. When the polymerization rate of vinyl acetate reaches 90%, m-dinitrobenzene is added to terminate the polymerization, and then unreacted vinyl acetate monomer is removed from the system by blowing methanol vapor. A methanol solution of the polymer was used.
Next, the methanol solution was further diluted with methanol, adjusted to a concentration of 45%, charged into a kneader, and while maintaining the solution temperature at 35 ° C., a 2% methanol solution of sodium hydroxide was added to vinyl acetate in the copolymer. Saponification was performed by adding 11.5 mmol with respect to 1 mol of the total amount of the structural unit and 3,4-diacetoxy-1-butene structural unit.
As saponification progressed, the saponified product precipitated and became particulate, and was filtered off. The obtained saponified product was thoroughly washed with methanol and dried with a hot air dryer to obtain a PVA resin (A1) having a side chain 1,2-diol structural unit of the above formula (1a).

The saponification degree of the obtained side chain 1,2-diol-containing PVA resin was analyzed by the alkali consumption required for hydrolysis of residual vinyl acetate and 3,4-diacetoxy-1-butene. Mol%. The average degree of polymerization was 450 when analyzed according to JIS K6726. The content of the 1,2-diol structural unit represented by the general formula (1a) is based on an integral value measured by ¹ H-NMR (300 MHz proton NMR, d6-DMSO solution, internal standard substance: tetramethylsilane). When calculated, it was 6 mol%. The MFR (210 ° C., load 2160 g) was 5.5 g / 10 minutes, and the melt viscosity (220 ° C., shear rate 122 sec ⁻¹ ) was 1148 Pa · s.

(2) Polyamide resin (B)
The following polyamide resin B1 or B2 was used.
B1: Nylon 6/66, “Novamid 2420J” (SP value 25.8) manufactured by Mitsubishi Engineering Corporation was used. The melt viscosity (220 ° C., shear rate 122 sec ⁻¹ ) is 1368 Pa · s.
B2: Nylon 11, “Rilsan P40” (SP value 20.8) manufactured by EMS Chemies Japan Ltd. was used. The melt viscosity (220 ° C., shear rate 122 sec ⁻¹ ) is 1557 Pa · s.

(3) Resin pellet and test piece No. Preparation of 1-4 PVA-based resin (A) and polyamide resin (B) were dry blended at a weight ratio shown in Table 1, and pelletized under the following conditions using a twin screw extruder (manufactured by Technobel). .
Screw diameter: 15mm
L / D = 60mm
Rotation direction: Same direction Screw pattern: Kneaded in 3 places Screen mesh: 90/90 mesh Screw rotation speed: 200 rpm
Temperature pattern: C1 / C2 / C3 / C4 / C5 / C6 / C7 / C8 / D = 180/195/210/210/215/220/220/220/220 ℃
Discharge rate: 15 kg / hr

  Using the prepared test piece, hydrogen gas barrier properties, flexibility, and durability were measured and evaluated based on the above-described measurement evaluation method. The results are shown in Table 1.

  No. in Table 1 3 and no. From the comparison of 4, the hydrogen gas permeation amount of the polyamide resin alone was about 4000 times the permeation amount of the side chain 1,2-diol-containing PVA. In this regard, no. From the comparison of 1-3, the hydrogen gas permeation amount when about 20% of the PVA resin was replaced with polyamide was less than twice, although increased compared to the case of the PVA resin alone. On the other hand, with respect to elongation, polyamide B1 (polyamide resin considered to have higher affinity with side chain 1,2-diol PVA-based resin) having a higher SP value, which is increased by blending with polyamide, has improved elongation at break. The effect was great.

  No. 1 and No. 2 is a case where 20% of the side chain 1,2-diol-containing PVA resin is replaced with a polyamide resin, and the hydrogen gas permeation amount is almost the same. For durability of the high-pressure hydrogen gas exposure-depressurization cycle test, see “No. In No. 2, blistering was observed. On the other hand, in the case of the polyamide resin alone having a hydrogen gas permeation amount as high as 4000 times (No. 4), generation of blisters was not recognized. For this reason, the high-pressure hydrogen gas exposure-depressurization cycle test is a phenomenon that can occur even when the gas permeation amount is small. It can be seen that this is a phenomenon.

  Therefore, it is presumed that the cause of blistering is caused by the interface between the PVA resin and the polyamide resin. In the polyamide 11 having an SP value of 20.8, the interaction between the polyamide and the PVA interface is weak. It is thought that it occurred. On the other hand, in polyamide 66/6 with SP value of 25.8, the bond at the interface (the relationship between the proton donor by the primary hydroxyl group and the proton acceptor at the amide bond) becomes stronger, and the PVA resin containing side chain 1,2 diol is used. As well as the islands composed of polyamide resin, the wettability of the interface between the side chain 1,2-diol-containing PVA resin and polyamide resin is strong, and as a result, even in the depressurization repeated cycle, It is thought that the generation of blisters due to hydrogen gas expansion is suppressed.

In addition, No. About 1 dumbbell-shaped test piece, solid NMR was measured before and after the durability test. The measurement conditions are as follows. In the measurement results before and after the durability test, there was no significant change in the resonance caused by intermolecular hydrogen bonds and the resonance line caused by intramolecular hydrogen bonds. This is because a layer (gas barrier layer) comprising a resin composition containing a side chain 1,2-diol-containing PVA resin (A) and a polyamide resin (B) having a solubility parameter of 22 to 28 MPa ^1/2. It can be said that there is almost no uptake of hydrogen gas due to the exposure and depressurization of high-pressure hydrogen gas, and there is no significant change in the solid structure.

・ Device: Bruker AVANCEIII 400WB
・ Probe: 4mmΦ CPMAS
・ Temperature: 22 ℃
・ Sample tube rotation speed: 5000 Hz
・ Measurement method: Inversion Recovery
・¹ H 90 ° pulse width: 4.2μsec × 44W
・¹³ C90 ° pulse width: 4.2μsec × 124W
・ Contact time 350μsec
・¹ H decoding sequence TPPM15
・¹ H decoupling power 44W (70 kHz)

  The hose for high-pressure gas transfer of the present invention has a high gas barrier property against a small molecule gas such as hydrogen, and also has excellent elongation and flexibility. It is useful as a hose for supplying high-pressure hydrogen gas such as that used for gas supply.

Claims (7)

At least a layer composed of a resin composition containing a polyvinyl alcohol resin (A) containing a structural unit represented by the following general formula (1) and a polyamide resin (B) having a solubility parameter of 22 to 28 MPa ^1/2. High pressure gas transfer hose with one layer.

[Wherein R ^{1 to} R ⁶ each independently represents a hydrogen atom or an organic group, and X represents a single bond or a bond chain] The high-pressure gas transfer hose according to claim 1, wherein a content weight ratio (A / B) of the polyvinyl alcohol resin (A) and the polyamide resin (B) is 90/10 to 75/25. The hose for high-pressure gas transfer according to claim 1 or 2, wherein the polyamide resin (B) has a melt viscosity of 200 to 2500 Pa · sec. The content rate of the said General formula (1) in the said polyvinyl alcohol-type resin (A) is 2-15 mol%, The hose for high pressure gas transfer in any one of Claims 1-3. The polyvinyl alcohol-based resin (A) has a content of structural units other than the structural unit represented by the formula (1) and a structural unit derived from a saponified vinyl ester monomer, of 50 mol% or less. The hose for high-pressure gas transfer according to any one of? The hose for high-pressure gas transfer according to any one of claims 1 to 5, wherein the layer made of the resin composition is an inner layer. The hose for high-pressure gas transfer according to any one of claims 1 to 6, which is for hydrogen gas transfer.

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