JP5497851B2 - Refrigerant transport hose and its polyamide resin composition for gas barrier layer formation - Google Patents

Description

  The present invention relates to a refrigerant transport hose, and more particularly, to a refrigerant transport hose having a gas barrier layer made of a polyamide resin composition. The present invention also relates to a polyamide resin composition for forming a gas barrier layer of the refrigerant transport hose.

  Conventionally, CFCs such as HFC-134a (R-134a) have been used as refrigerants in automobile air conditioners.

  From the viewpoint of improving ride comfort, rubber hoses with excellent vibration absorption performance are used in automotive air conditioner piping. The rubber hose has a gas barrier property in the innermost layer to prevent refrigerant leakage. A polyamide resin layer excellent in vibration durability such as impulse resistance is provided, an inner tube rubber layer is provided thereon, a reinforcing yarn layer made of organic fibers such as PET is provided thereon, and further thereon A structure in which an EPDM rubber layer having weather resistance is arranged is used (Patent Document 1).

  A refrigerant transport hose has also been proposed in which a polyolefin-based elastomer is blended as a flexibility-imparting agent with the polyamide resin constituting the innermost gas barrier layer to impart refrigerant resistance and flexibility (Patent Document 2).

However, polyamide resins have a problem of deterioration due to refrigerants such as CFCs and oil from compressors, and this problem cannot be solved even by blending polyolefin elastomers. For this reason, conventional refrigerant transport hoses are durable. There are still issues to be addressed.
For example, when an acidic component is present even in a small amount in an air conditioner system, the polyamide resin composition may be significantly deteriorated by the acidic component under high temperature / high pressure actual use conditions and may not be able to be used. As this acidic component, an extreme pressure agent contained in compressor oil sealed together with the refrigerant can be considered. For this reason, depending on the type of oil used in the air conditioner and the environmental conditions, the conventional refrigerant transport hose may not be practically durable and may not be usable.

  On the other hand, in a fiber reinforced hose for use in an oil hose for automobiles in which a fiber reinforcing layer is interposed between an inner layer and an outer layer made of an acrylic rubber containing an amine vulcanizing agent, hydrotalcite is added to the acrylic rubber. Containing an alcohol barrier layer formed on the outer periphery of the inner layer of the polyamide resin composition in the technology for preventing thermal deterioration of the reinforcing yarn during vulcanization molding (Patent Document 3) and the hose for gasohol fuel by blending Technologies for improving interlayer adhesion by blending hydrotalcite with a butyl rubber composition to be used (Patent Document 4) have been proposed. These technologies are based on the polyamide resin refrigerant and compressor oil which are the subject of the present invention. It does not suggest any prevention of deterioration due to.

JP 2007-15245 A JP 2000-120944 A JP 2001-116173 A JP 2008-265283 A

  The present invention has been made in view of the above-described conventional situation, and in a refrigerant transport hose having a gas barrier layer made of a polyamide resin composition containing a polyolefin-based elastomer, the gas barrier layer is deteriorated by refrigerant or compressor oil. It is an object of the present invention to provide a refrigerant transport hose that prevents and has excellent durability.

The refrigerant transport hose of the present invention (Claim 1) is a refrigerant transport hose having a gas barrier layer made of a polyamide resin composition containing a polyolefin-based elastomer and an inner rubber layer formed on the outer periphery of the gas barrier layer. The polyamide resin composition comprises one or more metal compounds selected from the group consisting of divalent or trivalent metal hydroxides, oxides and carbonates, and the metal compound and polymer component. 1 to 15% by weight based on the total, at least a part of the polyolefin-based elastomer is acid-modified, and the metal compound is hydrotalcite .

  A refrigerant transport hose according to claim 2 is characterized in that in claim 1, at least a part of the polyolefin-based elastomer is modified with maleic acid.

The refrigerant transporting hose according to claim 3, characterized in that in claim 1 or 2, the content of the polyolefin-based elastomer of the polyamide resin composition is 10 to 45% by weight relative to the total weight of the polyamide resin composition It is what.

A refrigerant transport hose according to a fourth aspect of the present invention is characterized in that, in any one of the first to third aspects, a reinforcing layer made of a reinforcing yarn and an outer rubber layer are provided on the outer peripheral side of the gas barrier layer. It is what.

The polyamide resin composition for forming a gas barrier layer of a refrigerant transport hose according to the present invention (invention 5 ) includes a gas barrier layer comprising a polyamide resin composition containing a polyolefin-based elastomer, and an inner layer rubber formed on the outer periphery of the gas barrier layer. In the polyamide resin composition for forming a gas barrier layer of a refrigerant transport hose having a layer, one or more metals selected from the group consisting of hydroxides, oxides and carbonates of divalent or trivalent metals The compound is contained in an amount of 1 to 15% by weight based on the total of the metal compound and the polymer component, at least a part of the polyolefin elastomer is acid-modified, and the metal compound is hydrotalcite. It is what.

A polyamide resin composition for forming a gas barrier layer of a refrigerant transport hose according to claim 6 is characterized in that, in claim 5 , at least a part of the polyolefin-based elastomer is modified with maleic acid.

The refrigerant transport hose of the present invention includes a polyamide resin composition constituting a gas barrier layer and a polyolefin-based elastomer that is at least partially acid-modified, a divalent or trivalent metal hydroxide, oxide, and One or two or more metal compounds selected from the group consisting of carbonates are blended in an amount of 1 to 15% by weight based on the total of the metal compound and the polymer component. Thus, by blending a specific metal compound in the polyamide resin composition at a predetermined ratio, the gas barrier layer made of this polyamide resin composition is effectively prevented from being deteriorated by refrigerant or compressor oil, and its durability is improved. Can be increased. Moreover, the softness | flexibility and durability of a gas barrier layer improve by mix | blending polyolefin-type elastomer with the polyamide resin composition which comprises a gas barrier layer. Further, compatibility with the polyamide resin is improved by at least a part of the polyolefin-based elastomer being acid-modified.
Although details of the action mechanism for preventing deterioration of the polyamide resin by the refrigerant or compressor oil due to the specific metal compound used in the present invention are not clear, the metal compound blended in the polyamide resin composition is an acid acceptor, a halogen acceptor, etc. It is presumed that the deterioration prevention effect of the polyamide resin is exhibited by the metal compound trapping deterioration factors such as an acid component and a halogen component contained in the refrigerant and oil.

  For this reason, the refrigerant transport hose of the present invention exhibits excellent durability performance without being affected by the oil used or the environment in the system used, and can be used stably and safely over a long period of time.

  In the present invention, it is preferable that at least a part of the polyolefin-based elastomer is modified with maleic acid (Claim 2).

  In the present invention, hydrotalcite is preferably used as the metal compound (claim 3).

  Moreover, in this invention, you may mix | blend 10-45 weight% of polyolefin-type elastomers with the polyamide resin composition which comprises a gas barrier layer, and, thereby, the softness | flexibility and durability of a gas barrier layer improve (Claim 4).

  In the refrigerant transport hose of the present invention, it is preferable that a reinforcing layer made of reinforcing yarn and an outer rubber layer are provided on the outer peripheral side of such a gas barrier layer.

  The polyamide resin composition for forming a gas barrier layer of the refrigerant transport hose of the present invention is one or two or more metal compounds selected from the group consisting of divalent or trivalent metal hydroxides, oxides and carbonates. In an amount of 1 to 15% by weight based on the total of the metal compound and the polymer component, and at least a part of the polyolefin elastomer is acid-modified, and is excellent in gas barrier properties and durability.

  In the present invention, it is preferable that at least a part of the polyolefin-based elastomer is modified with maleic acid (claim 7).

It is a perspective view which shows embodiment of the hose for refrigerant | coolant transportation of this invention.

  Hereinafter, embodiments of the present invention will be described in detail.

[Polyamide resin composition for forming gas barrier layer of refrigerant transport hose]
First, the polyamide resin composition for forming a gas barrier layer of the refrigerant transport hose of the present invention that constitutes the gas barrier layer of the refrigerant transport hose of the present invention will be described.

This polyamide resin composition comprises one or more metal compounds selected from the group consisting of divalent or trivalent metal hydroxides, oxides, and carbonates, and the metal compound and polymer component. It is characterized by containing 1 to 15% by weight based on the total.
Here, the polymer component in the polyamide resin composition refers to a total of a polyamide resin or a polymer component such as a polyamide resin and a polyolefin-based elastomer described later and other resins.

<Polyamide resin>
The polyamide resin used in the present invention is a polyamide resin mainly composed of amino acid, lactam or diamine and dicarboxylic acid. Specific examples of these components include lactams such as ε-caprolactam, enantolactam, ω-laurolactam, amino acids such as ε-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, tetramethylenediamine, hexa Methylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, m-xylylenediamine, p-xylylenediamine, 1 Diamines such as 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, bis-p-aminocyclohexylmethane, bis-p-aminocyclohexylpropane, isophoronediamine, adipic acid, suberic acid, azelaic acid, zebacic acid , Dodecanedioic acid, 1,4-cyclo Cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, dicarboxylic acids such as dimer acid. These constituent components are used for polymerization alone or in the form of a mixture of two or more, and the resulting poamide resin may be either a homopolymer or a copolymer.

  Polyamide resins (nylon 6), polyhexamethylene adipamide (nylon 66), polytetramethylene adipamide (nylon 46), polyhexamethylene sebamide (nylon 610) are particularly useful as the polyamide resin that is effectively used in the present invention. ), Polyundecanamide (nylon 11), polydodecanamide (nylon 12), polyhexamethylene adipamide / hexamethylene terephthalamide copolymer (nylon 66 / 6T), polycoupleramide / polyhexamethylene adipamide copolymer (Nylon 6/66) may be mentioned, and these may be used alone or in combination of two or more.

  The degree of polymerization of the polyamide is not particularly limited, and a 1% by weight sulfuric acid solution having a relative viscosity at 25 ° C. (hereinafter sometimes simply referred to as “relative viscosity”) in the range of 1.5 to 5.0. It can be used arbitrarily. In addition, in the polyamide resin, the terminal group concentration is adjusted by adding one or more of a monocarboxylic acid compound and / or a dicarboxylic acid compound or a monoamine compound and / or a diamine compound to the polyamide at an arbitrary stage. May be.

<Metal compound>
The metal compound contained in the polyamide resin composition of the present invention is selected from divalent or trivalent metal hydroxides, oxides, and carbonates.
Here, examples of the divalent or trivalent metal include divalent metals such as magnesium, iron, zinc, calcium, nickel, cobalt, and copper, and trivalent metals such as aluminum, iron, and manganese.
Specific examples of hydroxides, oxides and carbonates of these metals include hydrotalcite, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium oxide, and calcium carbonate. Hydrotalcite is preferred because it is considered to have an acid accepting effect.
These metal compounds may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Hydrotalcite is a kind of naturally occurring viscous mineral, and is a double hydroxide represented by the following general formula (I).
M ¹ _8-x M ² _x (OH) ₁₆ CO ₂ .nH ₂ O (I)

In formula (I), M ¹ is Mg ²⁺ , Fe ²⁺ , Zn ²⁺ , Ca ²⁺ , Li ²⁺ , Ni ²⁺ , Co ²⁺ , Cu ^2+, etc., M ² is Al ³⁺ , Fe ³⁺ , Mn ^3+, etc. ≦ x ≦ 2 and n ≧ 0.

As hydrotalcite, in the form containing crystal water, for example, Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O, Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ , Mg ₄ Al ₂ (OH) ₁₂ CO ₃ .3.5H ₂ O, Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O, Mg ₅ Al ₂ (OH) ₁₄ CO ₃ .4H ₂ O, Mg ₃ Al ₂ (OH) ₁₀ CO _{3 · 1.7H 2 O, Mg 3 ZnAl} 2 (OH) 12 CO 3 · wH 2 O, Mg 3 ZnAl 2 (OH) 12 CO 3 and the like. Examples of commercially available hydrous hydrotalcite include “DHT-4A” and “DHT-6” manufactured by Kyowa Chemical Industry Co., Ltd.

  If the content of the metal compound in the polyamide resin composition is too small, the deterioration prevention effect due to the compounding of the metal compound cannot be sufficiently obtained, and if it is too much, an effect commensurate with the compounding amount cannot be obtained. As a result, the properties such as gas barrier properties, flexibility, and aging resistance are impaired. Therefore, the content of the metal compound in the polyamide resin composition is 1 to 15% by weight, preferably 1 to 5% by weight, based on the total of the metal compound and the polymer component in the polyamide resin composition.

<Polyolefin elastomer>
You may mix | blend polyolefin-type elastomer with the polyamide resin composition of this invention. By blending the polyolefin-based elastomer, flexibility and durability of the gas barrier layer composed of the polyamide resin composition can be imparted.

  Examples of the olefin elastomer include ethylene / butene copolymer, EPR (ethylene-propylene copolymer), modified ethylene / butene copolymer, EEA (ethylene-ethyl acrylate copolymer), modified EEA, modified EPR, Modified EPDM (ethylene-propylene-diene terpolymer), ionomer, α-olefin copolymer, modified IR (isoprene rubber), modified SEBS (styrene-ethylene-butylene-styrene copolymer), halogenated isobutylene- Examples thereof include a paramethylstyrene copolymer, an ethylene-acrylic acid modified product, an ethylene-vinyl acetate copolymer, an acid-modified product thereof, and a mixture containing them as a main component. These may be used alone or in combination of two or more.

  Polyolefin-based elastomers, especially those modified with acid anhydrides such as maleic anhydride, alkyl acrylate esters such as glycidyl methacrylate, epoxies, and modified products thereof, have a fine alloy structure based on polyamide resin. It can be obtained and is preferable.

  If the polyolefin elastomer content in the polyamide resin composition according to the present invention is too small, the effect of improving the flexibility and durability due to the blending of the polyolefin elastomer cannot be sufficiently obtained, and if too large, the gas barrier property Therefore, the content in the polyamide resin composition is preferably 10 to 45% by weight, particularly preferably 20 to 40% by weight. If the content of the polyolefin-based elastomer in the polyamide resin composition is too large, the sea phase and the island phase are reversed in the sea-island structure described later, and the gas barrier property is remarkably lowered.

When a modified elastomer such as an acid-modified elastomer is used as the polyolefin-based elastomer, an effect that less specific energy and a high kneading technique are not required at the time of kneading (dispersing) can be obtained. In the case of using a modified elastomer as the polyolefin-based elastomer, the content of the modified elastomer in the polyamide resin composition is 20% by weight or less, for example, It is preferable to set it as 5 to 20 weight%.
In particular, in the present invention, it is preferable that 40 to 100% by weight of the polyolefin elastomer in the polyamide resin composition is an acid-modified elastomer.

In order to make the polyamide resin composition and the polyolefin elastomer compatible with each other, that is, in a good dispersion state, it is preferable that at least a part of the elastomer is modified with maleic anhydride or the like to obtain a good dispersion form. Therefore, it is preferable that the average acid value (acid modification rate) of the whole elastomer used is 0.8 mg-CH ₃ ONa / g or more.

The higher the acid value of the elastomer, the better the dispersion form, but the viscosity of the polyamide resin composition obtained with an increase in the acid value increases and the molding processability is impaired. For this reason, in order to reduce the increase in viscosity due to the increase in the acid value, the acid value of the elastomer is preferably low in a range where a good dispersion state can be obtained, and the average acid value of the whole elastomer used is 7.5 mg. is preferably not more than -CH ₃ ONa / g.

Moreover, even if the average acid value is the same, when the acid value of the modified elastomer contained in the elastomer to be used is high, the modified elastomer is mixed with the unmodified elastomer, thereby extruding even if the average acid value is lowered. Occasionally, gel-like foreign substances appear due to local overreaction. Therefore, the acid value of the modified elastomer to be used is preferably 15.0 mg-CH ₃ ONa / g or less.

  Thus, by blending the polyolefin-based elastomer with the polyamide resin composition, the flexibility and durability are improved, but the gas barrier property is inevitably lowered. However, by adopting a fine alloy structure of polyamide resin and elastomer, the island phase of the elastomer is dispersed in the sea phase of the polyamide resin, and the polyamide resin is dispersed in the form of dots in the island phase of the elastomer. With such a structure, a decrease in gas barrier properties due to the blending of the elastomer can be suppressed, which is preferable.

  In particular, the ratio of the polyamide resin phase that is scattered in the island phase of the elastomer to the polyamide resin (the total of the polyamide resin that constitutes the sea phase and the polyamide resin phase that is scattered in the island phase of the elastomer) (Hereinafter, the ratio is referred to as “spot dispersion”) is preferably about 5 to 40% by weight. If this proportion is less than 5% by weight, it is not possible to sufficiently obtain the effect of the presence of the polyamide resin phase in the form of scattered dots in the island phase of the elastomer. There is a possibility that the polyamide resin phase becomes too small and the gas barrier property is lowered.

  The size of the elastomeric island phase and the size of the polyamide resin phase in the elastomeric island phase are approximately 0.1 to 3.0 μm for the elastomeric island phase and 0.5 for the polyamide resin phase. It is preferable that it is about -2.0 micrometers.

<Other ingredients>
The polyamide resin composition of the present invention may contain a resin component other than the polyamide resin as a resin component. In that case, 70% by weight or more of the total polymer component in the refrigerant transport hose is a polyamide resin. It is preferable to ensure gas barrier properties.

  Examples of other resin components in this case include ethylene / vinyl alcohol resin.

  Further, the polyamide resin composition of the present invention includes other additives, that is, a lubricant, an antistatic agent, an anti-aging agent, an antioxidant, a coloring agent, a crystal nucleating agent, a filler, a reinforcing material, a heat resistance agent, and a light resistance agent. Etc. can also be added.

[Hose for refrigerant transport]
Next, the refrigerant transport hose of the present invention using the polyamide resin composition for forming a gas barrier layer of the refrigerant transport hose as a constituent material of the gas barrier layer will be described with reference to the drawings.

  FIG. 1 is a perspective view for explaining a layer structure of a refrigerant transport hose 1 according to an embodiment. The innermost layer of the refrigerant transport hose 1 is composed of the gas barrier layer 2 made of the above-described polyamide resin composition for gas barrier layer formation of the refrigerant transport hose of the present invention, and the inner rubber layer 3 is formed on the outer periphery thereof. A first reinforcing yarn layer 4, an intermediate rubber layer 5, a second reinforcing yarn layer 6, and a jacket rubber layer 7 are formed in sequence. The inner diameter of the hose 1 is usually about 6 to 20 mm, particularly about 8 to 19 mm.

  Hereinafter, the material of each layer will be described.

<Gas barrier layer>
The gas barrier layer 2 is made of the polyamide resin composition for forming a gas barrier layer of the refrigerant transport hose of the present invention, in which the above-mentioned metal compound is blended in an amount of 1 to 15% by weight based on the total of the metal compound and the polymer component.

The thickness of the gas barrier layer 1 made of such a polyamide resin composition is preferably thicker from the viewpoint of gas barrier properties. However, as the film thickness increases, the flexibility as a hose decreases.
Therefore, the film thickness of the gas barrier layer 2 is preferably 50 to 400 μm, particularly preferably 100 to 300 μm.

  In the refrigerant transport hose of the present invention, an inner rubber layer may be further formed as an innermost layer on the inner layer of the gas barrier layer 2 in the refrigerant transport hose 10 of FIG.

  There is no restriction | limiting in particular about the other structure of the refrigerant | coolant transport hose of this invention, The structure of the normal refrigerant | coolant transport hose is employable as follows.

<Inner rubber layer 3, outer rubber layer 7 and intermediate rubber layer 5>
As the rubber constituting the inner rubber layer 3 and the outer rubber layer 7, butyl rubber (IIR), chlorinated butyl rubber (C1-IIR), chlorinated polyethylene, chlorosulfonated polyethylene, brominated butyl rubber (Br-IIR), Isobutylene-bromoparamethylstyrene copolymer, EPR (ethylene-propylene copolymer), EPDM (ethylene-propylene-diene terpolymer), NBR (acrylonitrile butadiene rubber), CR (chloroprene rubber), hydrogenated NBR Acrylic rubber, ethylene acrylic rubber (AEM), a blend of two or more of these rubbers, or a blend with a polymer based on these rubbers, preferably butyl rubber or EPDM rubber. . These rubbers can be applied with compounding recipes such as commonly used fillers, processing aids, anti-aging agents, vulcanizing agents, and vulcanization accelerators.

  The rubber type of the inner rubber layer 3 and the rubber type of the jacket rubber layer 7 may be the same or different.

  Moreover, the rubber | gum of the intermediate | middle rubber layer 5 should just have the adhesiveness with the inner-layer rubber layer 2 and the jacket rubber layer 7, and there is no restriction | limiting in particular.

  The thickness of the inner rubber layer 3 is preferably about 0.5 to 4 mm from the viewpoint of flexibility. The thickness of the intermediate rubber layer 5 is preferably about 0.1 to 0.6 mm, and the thickness of the outer rubber layer 7 is preferably about 0.5 to 2 mm.

<Reinforcing thread layers 4, 6>
The first reinforcing yarn layer 4 is obtained by winding a reinforcing yarn in a spiral shape, and the second reinforcing yarn layer 6 is obtained by winding a reinforcing yarn in a spiral shape in the opposite direction to the first reinforcing yarn layer 4. is there.

  The material of the reinforcing yarn is not particularly limited as long as it is usually used. In general, polyester, wholly aromatic polyester, nylon, vinylon, rayon, aramid, polyarylate, polyethylene naphthalate and blended yarns thereof are used.

<Method for manufacturing refrigerant transport hose>
Such a refrigerant transport hose according to the present invention is formed by extruding the material of the gas barrier layer 2 and the inner rubber layer 3 to a predetermined thickness on a mandrel and laminating them on the mandrel, and winding the reinforcing yarn layer 4 on the intermediate rubber layer. 5 is extruded and laminated, the reinforcing yarn layer 6 is wound, then the outer rubber layer 7 is extruded and laminated, and then vulcanized at 140 to 170 ° C. for 30 to 120 minutes.

[Test example]
Below, the test example equivalent to an Example, a reference example, and a comparative example performed about the polyamide-type resin piece is demonstrated.

  Each material was kneaded with the formulation shown in Table 1 and Table 2 to produce a polyamide resin piece for testing. In the kneading, a twin-screw kneader manufactured by Toyo Seiki Co., Ltd. was used and kneaded at a temperature of 230 ° C. above the melting point of the polyamide resin.

  The materials used for the production of the test polyamide resin pieces are as follows.

Polyamide 6: 6 nylon “1022B” manufactured by Ube Industries, Ltd.
Elastomer: Mitsui Chemicals Co., Ltd. α-olefin polymer (ethylene butene copolymer) “Tuffmer A-1050S”
Maleic acid-modified elastomer: maleic acid-modified α-olefin polymer (ethylene / butene copolymer) “Tuffmer MH7010” manufactured by Mitsui Chemicals, Inc.
Hydrotalcite A: “Hydrotalcite DHT-4A” manufactured by Kyowa Chemical Co., Ltd.
Composition formula: Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O
Magnesium oxide: “Kyowa Mug 30” manufactured by Kyowa Chemical Co., Ltd.
Composition formula: MgO

  About the obtained polyamide-type resin piece for a test, the characteristic evaluation was performed by the following method and the result was shown to Table 1,2.

<Elastomer dispersibility>
Using an electron microscope (SEM), observe the test polyamide resin piece surface-treated with phosphotungstic acid to examine the dispersed particle size of the elastomer. If the elastomer dispersed particle size is 3 μm or less, OK is greater than 3 μm. It was.

<4% elongation elastic modulus index>
Using a tensile tester manufactured by Toyo Seiki Co., Ltd., each test polyamide resin piece was stretched at a pulling speed of 50 mm / min to measure the modulus of elasticity, and an index relative to the test polyamide resin piece (100) of Comparative Example 1 was used. Indicated.

<Gas permeability index>
Using a gas permeation tester manufactured by GTR Tech, the He gas permeability coefficient was measured at 100 ° C. with an absolute differential pressure of 226 cmHg for each polyamide resin piece for testing, and an index for the polyamide resin piece for testing (100) in Comparative Example 1 The notation.

<Strong retention after aging>
Using a tensile tester manufactured by Toyo Seiki Co., Ltd., for each test polyamide resin piece before and after the aging test, the tensile strength was measured by stretching at a tensile speed of 50 mm / min, and after the aging test with respect to the value before the aging test Expressed as a percentage of the value.

<Elongation at break after aging>
Using a tensile tester manufactured by Toyo Seiki Co., Ltd., for each test polyamide resin piece before and after the following aging test, the elongation at break was measured at a tensile rate of 50 mm / min, and the rupture elongation was measured with respect to the value before the aging test. Expressed as a percentage of the value.

(Aging test)
The following procedures 1 to 7 were performed.
1 Put 1 cc of water in a pressure vessel.
2 Insert a test polyamide-based resin piece of width 10 × length 50 mm × thickness 0.1 mm.
3 Add 100 cc of polyalkylene glycol oil.
4 After freezing the pressure vessel for 15 minutes, vacuum the pressure vessel for 5 minutes.
5 Add 100 cc of R-134a as refrigerant.
6 Leave in a high temperature bath at 150 ° C for 4 weeks.
7. Remove the test polyamide resin piece from the container and use it for evaluation measurement.

<Surface roughness>
The center line average roughness was measured according to JIS B0601 using a “surface roughness measuring device Surfcorder SE-2300” manufactured by Kosaka Laboratory.

  From Tables 1 and 2, it can be seen that the refrigerant transport hose of the present invention obtained by blending a predetermined amount of a metal compound with the polyamide resin composition for a gas barrier layer is excellent in gas barrier properties, flexibility and durability.

  From Tables 1 and 2, it can be seen that the refrigerant transport hose of the present invention obtained by blending a predetermined amount of a metal compound with the polyamide resin composition for a gas barrier layer is excellent in gas barrier properties, flexibility and durability. As shown in Table 1, the surface roughness Ra is smaller in Reference Example 1 and Example 5 than in Reference Examples 3 and 4.

DESCRIPTION OF SYMBOLS 1 Refrigerant transport hose 2 Gas barrier layer 3 Inner rubber layer 4,6 Reinforcing thread layer 5 Intermediate rubber layer 7 Outer rubber layer

Claims (6)

In a refrigerant transport hose having a gas barrier layer comprising a polyamide resin composition containing a polyolefin-based elastomer, and an inner rubber layer formed on the outer periphery of the gas barrier layer,
The polyamide resin composition comprises one or more metal compounds selected from the group consisting of divalent or trivalent metal hydroxides, oxides and carbonates, and the total of the metal compound and the polymer component. 1 to 15% by weight based on the weight, at least a part of the polyolefin-based elastomer is acid-modified, and the metal compound is hydrotalcite .   The refrigerant transport hose according to claim 1, wherein at least a part of the polyolefin-based elastomer is modified with maleic acid. 3. The refrigerant transport hose according to claim 1 , wherein the content of the polyolefin-based elastomer in the polyamide resin composition is 10 to 45% by weight based on the total weight of the polyamide resin composition. In any one of claims 1 to 3, wherein the outer peripheral side of the gas barrier layer, the refrigerant transporting hose, characterized in that the reinforcing layer and the external rubber layer is provided consisting of reinforcing threads. A polyamide resin composition for forming a gas barrier layer of a refrigerant transport hose having a gas barrier layer comprising a polyamide resin composition containing a polyolefin-based elastomer and an inner rubber layer formed on the outer periphery of the gas barrier layer. 1 to 15% by weight of one or more metal compounds selected from the group consisting of hydroxides, oxides and carbonates of a valent metal with respect to the total of the metal compound and the polymer component, A polyamide resin composition for forming a gas barrier layer of a refrigerant transport hose , wherein at least a part of the polyolefin elastomer is acid-modified and the metal compound is hydrotalcite . 6. The polyamide resin composition for forming a gas barrier layer of a refrigerant transport hose according to claim 5 , wherein at least a part of the polyolefin-based elastomer is modified with maleic acid.

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