Hose for transporting refrigerant and method for manufacturing same

Abstract

Provided is a hose for transporting a refrigerant, which has excellent flexibility, water vapor barrier properties, and heat resistance. A hose (1) for transporting a refrigerant, which comprises an outer layer (4), a reinforcing layer (3), and an inner layer (2), and which is characterized in that the outer layer comprises a resin composition that contains 100 parts by mass of an elastomer having a polyisobutylene skeleton, 10-150 parts by mass of a crosslinked resin, and 2.5-25 parts by mass of a crosslinking agent for the elastomer having a polyisobutylene skeleton; the water vapor transmission rate of the resin composition constituting the outer layer is 3.0 g * mm / (m < 2 > * 24 h) or less.

Description

Technical Field

[0001] The present invention relates to a refrigerant transport hose and a method for manufacturing the same. More specifically, the present invention relates to a refrigerant transport hose used in an automobile air conditioner and a method for manufacturing the refrigerant transport hose. Background Art

[0002] As the demand for lightweight cars continues to increase, there is a measure to achieve lightweighting by using resin with high barrier properties instead of rubber to make rubber hoses that have been used in cars and making them thinner. In particular, the main material of the refrigerant delivery hose of existing car air conditioners is rubber. If this main material can be replaced with resin with high barrier properties, lightweighting can be achieved.

[0003] Japanese Patent Application Laid-Open No. 4-145284 (Patent Document 1) describes a hose for conveying a refrigerant such as Freon gas, wherein an outer tube thereof is formed using a thermoplastic elastomer composed of a thermoplastic polyolefin resin and EPDM or butyl rubber.

[0004] Prior Art Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 4-145284 Summary of the invention

[0006] Problems to be solved by the invention

[0007] Automobile air conditioners are installed in a limited and narrow space in the automobile, so the refrigerant delivery hose is required to be highly flexible and easy to install even in a narrow space. In addition, the penetration of water vapor from the outside of the hose causes water to freeze inside the air conditioner, so the material forming the outer tube of the refrigerant delivery hose needs to have excellent water vapor barrier properties. In addition, it is also required to be durable enough to be used for a long time in the high temperature and high humidity environment of the engine room.

[0008] However, since the outer tube of the resin hose described in Patent Document 1 is formed of a thermoplastic elastomer containing a thermoplastic polyolefin resin, the heat resistance is not necessarily sufficient.

[0009] An object of the present invention is to provide a hose for transporting refrigerant having excellent flexibility, water vapor barrier properties, and heat resistance.

[0010] Means for solving problems

[0011] The present invention (I) relates to a hose for transporting a refrigerant comprising an outer layer, a reinforcing layer and an inner layer, wherein the outer layer is composed of a resin composition, the resin composition comprising 100 parts by mass of an elastomer having a polyisobutylene skeleton, 10 to 150 parts by mass of a cross-linking resin and 2.5 to 25 parts by mass of a cross-linking agent for the elastomer having a polyisobutylene skeleton, and the water vapor permeability of the resin composition constituting the outer layer is 3.0 g·mm / (m 2 24h) or less.

[0012] The present invention (II) relates to a method for manufacturing a refrigerant transport hose of the present invention (I), characterized in that the method comprises: a step of melt-kneading an elastomer having a polyisobutylene skeleton, a cross-linking resin and a cross-linking agent for the elastomer having a polyisobutylene skeleton to prepare an outer layer composition, and a step of adding a silanol condensation catalyst to the outer layer composition during extrusion molding of the hose, and extruding the composition to which the silanol condensation catalyst was added to form an outer layer.

[0013] The present invention includes the following technical solutions.

[0014] [1] A hose for transporting refrigerant, comprising an outer layer, a reinforcing layer and an inner layer, wherein the outer layer is composed of a resin composition, the resin composition comprising 100 parts by mass of an elastomer having a polyisobutylene skeleton, 10 to 150 parts by mass of a cross-linking resin and 2.5 to 25 parts by mass of a cross-linking agent for the elastomer having a polyisobutylene skeleton, and the water vapor permeability of the resin composition constituting the outer layer is 3.0 g·mm / (m 2 24h) or less.

[0015] [2] The refrigerant transport hose according to [1], wherein the cross-linking agent of the elastomer having a polyisobutylene skeleton contains zinc white and an alkylphenol formaldehyde-based resin.

[0016] [3] The refrigerant transport hose according to [1] or [2], wherein the resin composition constituting the outer layer comprises 1 to 10 parts by mass of zinc white based on 100 parts by mass of the elastomer having a polyisobutylene skeleton, and 1.5 to 15 parts by mass of the alkylphenol formaldehyde resin based on 100 parts by mass of the elastomer having a polyisobutylene skeleton.

[0017] [4] The refrigerant transport hose according to any one of [1] to [3], wherein the elastomer having a polyisobutylene skeleton in the resin composition constituting the outer layer is butyl rubber or modified butyl rubber, and the elastomer having a polyisobutylene skeleton is dynamically crosslinked.

[0018] [5] The refrigerant transport hose according to any one of [1] to [4], wherein the cross-linked resin in the resin composition constituting the outer layer is a silane-modified resin obtained by cross-linking a thermoplastic resin modified with a silane compound.

[0019] [6] The refrigerant transport hose according to any one of [1] to [5], wherein the crosslinked resin in the resin composition constituting the outer layer is a silane-modified polyolefin crosslinked with a polyolefin modified with a silane compound.

[0020] [7] The refrigerant transport hose according to any one of [1] to [6], wherein the cross-linked resin in the resin composition constituting the outer layer is a cross-linked silane-modified polypropylene obtained by modifying polypropylene with a silane compound.

[0021] [8] The refrigerant transport hose according to any one of [1] to [7], wherein the resin composition constituting the outer layer contains 1 to 10 parts by mass of an antioxidant based on 100 parts by mass of the elastomer having a polyisobutylene skeleton.

[0022] [9] The refrigerant transport hose according to any one of [1] to [8], wherein the resin composition constituting the outer layer has a breaking strength TB at 150°C. 150 It is above 1.0MPa.

[0023]

[10] The refrigerant transport hose according to any one of [1] to [9], wherein the resin composition constituting the outer layer comprises a matrix containing a cross-linked resin and domains containing an elastomer having a polyisobutylene skeleton dispersed in the matrix, and the matrix is ​​cross-linked.

[0024]

[11] The refrigerant transport hose according to any one of [1] to

[10] , wherein the resin composition constituting the outer layer comprises a matrix containing a cross-linked resin and a domain containing an elastomer having a polyisobutylene skeleton dispersed in the matrix, and the domain is cross-linked.

[0025]

[12] A refrigerant transport hose according to any one of [1] to

[11] , wherein the inner layer is composed of a thermoplastic resin composition containing 100 parts by mass of an elastomer and 30 to 170 parts by mass of a thermoplastic resin, the thermoplastic resin composition having a sea-island structure in which the elastomer exists as a structural domain in a matrix containing the thermoplastic resin, the thermoplastic resin contains 50 to 100 parts by mass of a polyamide based on 100 parts by mass of the thermoplastic resin, the elastomer includes an elastomer having a polyisobutylene skeleton, and the thermoplastic resin composition further contains a processing aid and a phenylenediamine-based or quinoline-based antioxidant.

[0026]

[13] A method for manufacturing a refrigerant transport hose as described in any one of [1] to

[12] , the method comprising: a step of melt-kneading an elastomer having a polyisobutylene skeleton, a cross-linking resin, and a cross-linking agent for the elastomer having a polyisobutylene skeleton to prepare an outer layer composition; and a step of adding a silanol condensation catalyst to the outer layer composition during extrusion molding of the hose, and extruding the composition to which the silanol condensation catalyst was added to form an outer layer.

[0027]

[14] The method according to

[13] , further comprising, after the step of forming the outer layer, bringing the outer layer into contact with water or water vapor to crosslink the matrix in the resin composition constituting the outer layer.

[0028] Effects of the Invention

[0029] The refrigerant transport hose of the present invention is excellent in flexibility, water vapor barrier properties and heat resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a cross-sectional view of a hose for transporting refrigerant.

[0031] Figure 2 This is a diagram showing a method for evaluating the flexibility of a hose. DETAILED DESCRIPTION

[0032] The present invention (I) relates to a hose for transporting a refrigerant.

[0033] The refrigerant transport hose refers to a hose used to transport refrigerants for air conditioners and the like. The refrigerant transport hose of the present invention is particularly suitable as a hose for transporting refrigerants for automobile air conditioners. Examples of refrigerants for air conditioners include hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), hydrocarbons, carbon dioxide, ammonia, water, and the like. Examples of HFCs include R410A, R32, R404A, R407C, R507A, and R134a. Examples of HFOs include R1234yf, R1234ze, 1233zd, R1123, R1224yd, and R1336mzz. Examples of hydrocarbons include methane, ethane, propane, propylene, butane, isobutane, hexafluoropropane, and pentane.

[0034] The refrigerant transport hose of the present invention comprises an outer layer, a reinforcement layer and an inner layer.

[0035] A cross-sectional view of one embodiment of the refrigerant transport hose of the present invention is shown in Figure 1 However, the present invention is not limited to Figure 1 shown.

[0036] The refrigerant-transporting hose 1 includes an inner layer 2 , a reinforcement layer 3 disposed outside the inner layer 2 , and an outer layer 4 disposed outside the reinforcement layer 3 .

[0037] The outer layer is composed of a resin composition containing 100 parts by mass of an elastomer having a polyisobutylene skeleton, 10 to 150 parts by mass of a crosslinking resin, and 2.5 to 25 parts by mass of a crosslinking agent for the elastomer having a polyisobutylene skeleton.

[0038] The elastomer having a polyisobutylene skeleton is not limited as long as it has a polyisobutylene skeleton, but is preferably butyl rubber (IIR), modified butyl rubber, or styrene-isobutylene-styrene block copolymer, and more preferably butyl rubber or modified butyl rubber.

[0039] The polyisobutylene skeleton refers to the chemical structure formed by the polymerization of multiple isobutylenes, namely, -[-CH2-C(CH3)2-] n - (wherein n is an integer greater than or equal to 2).

[0040] Butyl rubber refers to an isobutylene-isoprene copolymer obtained by copolymerizing isobutylene with a small amount of isoprene, and is abbreviated as IIR.

[0041] Modified butyl rubber refers to butyl rubber having double bonds and halogens in the isoprene skeleton. The modified butyl rubber is preferably halogenated butyl rubber, more preferably brominated butyl rubber or chlorinated butyl rubber, and still more preferably brominated butyl rubber.

[0042] Styrene-isobutylene-styrene block copolymer is referred to as SIBS.

[0043] When the resin composition contains an elastomer having a polyisobutylene skeleton, the flexibility and water vapor barrier properties of the resin composition are improved.

[0044] The elastomer having a polyisobutylene skeleton is preferably dynamically crosslinked. Dynamic crosslinking improves durability.

[0045] The resin composition constituting the outer layer contains a crosslinked resin. The resin composition contains a crosslinked resin, and thus has excellent heat resistance.

[0046] Cross-linked resin refers to a cross-linked resin. The cross-linked resin is not limited, but preferably a cross-linked resin obtained by cross-linking a silane-modified resin. A silane-modified resin refers to a resin obtained by modifying a thermoplastic resin with a silane compound. The silane-modified resin is preferably a resin obtained by modifying a polyolefin-based thermoplastic resin with a silane compound, and more preferably a cross-linked resin having a hydrolyzable silyl group (preferably an alkoxysilyl group) obtained by modifying a polyolefin-based thermoplastic resin with a silane compound.

[0047] That is, the crosslinked resin is preferably a resin obtained by crosslinking a silane-modified resin obtained by modifying a thermoplastic resin with a silane compound, more preferably a resin obtained by crosslinking a silane-modified polyolefin obtained by modifying a polyolefin with a silane compound, and further preferably a resin obtained by crosslinking a silane-modified polypropylene obtained by modifying a polypropylene with a silane compound.

[0048] The silane compound is not limited, but is preferably a compound represented by formula (1).

[0049] R 1 -SiR 2 n Y 3-n (1)

[0050] Among them, R 1 is an olefinic (ethylenically) unsaturated hydrocarbon group, R 2 is a hydrocarbon group, Y is a hydrolyzable organic group, and n is an integer of 0 to 2.

[0051] R 1 It is preferably an ethylenically unsaturated hydrocarbon group having 2 to 10 carbon atoms, and examples thereof include a vinyl group, a propenyl group, a butenyl group, a cyclohexenyl group, and a γ-(meth)acryloyloxypropyl group.

[0052] R 2 It is preferably a hydrocarbon group having 1 to 10 carbon atoms, and examples thereof include methyl group, ethyl group, propyl group, decyl group, and phenyl group.

[0053] Y is preferably a hydrolyzable organic group having 1 to 10 carbon atoms, and examples thereof include methoxy, ethoxy, formyloxy, acetoxy, propionyloxy, alkylamino, and arylamino.

[0054] Specific examples of the silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and γ-methacryloxypropyltrimethoxysilane. Among them, vinyltrimethoxysilane is preferred.

[0055] The polyolefin-based thermoplastic resin constituting the silane-modified resin is not limited, and examples thereof include polyethylene, copolymers of ethylene and α-olefins, polypropylene, copolymers of propylene and other α-olefins, etc. Polypropylene and copolymers of propylene and other α-olefins are preferred, and polypropylene is particularly preferred.

[0056] The hydrolyzable silyl group is a group that generates a silanol group (≡Si—OH) by hydrolysis, and is preferably a group represented by the formula (2).

[0057] -SiR 2 n Y 3-n (2)

[0058] Among them, R 2 and Y as described above.

[0059] The crosslinkable resin refers to a resin that is capable of undergoing a crosslinking reaction but has not yet been crosslinked. The type of the crosslinking reaction is not limited, and crosslinking using a peroxide may be used, and crosslinking using moisture (water crosslinking) is preferred.

[0060] The method of modification with silane compounds is not limited, and grafting or copolymerization can be cited. Grafting is a method of adding a silane compound to a resin by a grafting reaction, more specifically, a reaction in which a carbon-hydrogen bond of a polyolefin is cleaved to generate a carbon radical, and a silane compound having an ethylenically unsaturated hydrocarbon group is added thereto. The modification can preferably be carried out by melt-kneading the resin with a silane compound of formula (1) in the presence of a free radical initiator such as an organic peroxide. Copolymerization can preferably be carried out by free radical copolymerization of the monomer constituting the resin with the silane compound of formula (1).

[0061] The silane-modified resin is preferably silane-modified polypropylene. Silane-modified resins are commercially available, and commercially available products can be used as the silane-modified resin used in the present invention. Examples of commercially available silane-modified resins include "Linklon" (registered trademark) manufactured by Mitsubishi Chemical Corporation.

[0062] The content of the crosslinked resin is 10 to 150 parts by mass, preferably 10 to 100 parts by mass, and more preferably 10 to 80 parts by mass, based on 100 parts by mass of the elastomer having a polyisobutylene skeleton. If the content of the crosslinked resin is too small, extrusion processability deteriorates, and if it is too large, flexibility cannot be ensured.

[0063] The resin composition constituting the outer layer may contain a resin other than the cross-linked resin.

[0064] As resins other than cross-linked resins, polyolefin resins, polyamide resins, etc. can be cited. As polyolefin resins, polypropylene can be cited. By including polypropylene on the basis of the silane-modified resin, the viscosity of the resin component is stabilized, so that a phase structure that easily exhibits heat strength is formed. In addition, since polypropylene has good water vapor barrier properties, the water vapor barrier properties of the entire composition are good.

[0065] The resin composition constituting the outer layer contains a crosslinking agent for an elastomer having a polyisobutylene skeleton. Hereinafter, the "crosslinking agent for an elastomer having a polyisobutylene skeleton" is also referred to as a "crosslinking agent". The resin composition contains a crosslinking agent, and the heat resistance after crosslinking (dynamic crosslinking) is improved.

[0066] The crosslinking agent preferably contains zinc white and an alkylphenol formaldehyde resin. When the crosslinking agent contains zinc white and an alkylphenol formaldehyde resin, the crosslinked (dynamically crosslinked) resin composition can be endowed with heat resistance to a 150°C environment.

[0067] Zinc white refers to zinc oxide, which is an oxide of zinc represented by the chemical formula ZnO. Zinc white is available on the market, and commercially available products can be used in the present invention. Examples of commercially available products include three types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.

[0068] The alkylphenol formaldehyde resin refers to a compound represented by the formula (3).

[0069]

[0070] In formula (3), X is a hydroxyl group or a halogen, Y and Y' are hydrogen or an alkyl group, Z is an alkyl group or a halogen, and n is an integer of 0 to 20. The halogen constituting X and Z is preferably fluorine, chlorine, bromine or iodine, more preferably bromine. The alkyl group constituting Y, Y' and Z is preferably an alkyl group having 1 to 8 carbon atoms.

[0071] The structural formula represented by formula (3) is a straight chain, but the alkylphenol formaldehyde resin can be synthesized according to a conventional method to have a branched part.

[0072] When X is bromine, it is called brominated alkylphenol formaldehyde resin.

[0073] Alkylphenol formaldehyde resins are commercially available, and commercially available products can be used in the present invention. Examples of commercially available products include alkylphenol-formaldehyde resin "Hitanol" (registered trademark) 2501Y manufactured by Hitachi Chemical Co., Ltd.

[0074] The content of the crosslinking agent is 2.5 to 25 parts by mass, preferably 2.5 to 20 parts by mass, and more preferably 2.5 to 18 parts by mass, based on 100 parts by mass of the elastomer having a polyisobutylene skeleton. If the content of the crosslinking agent is too small, the dynamic crosslinking of the elastomer is insufficient, and the strength during heat treatment is reduced. If the content of the crosslinking agent is too large, the silane crosslinking of the resin is inhibited, and the strength during heat treatment is reduced.

[0075] The content of zinc white is 1 to 10 parts by mass, preferably 2 to 8 parts by mass, and more preferably 3 to 8 parts by mass, based on 100 parts by mass of the elastomer having a polyisobutylene skeleton. If the content of zinc white is too low, the dynamic crosslinking of the elastomer is insufficient, and the strength during heat treatment is reduced. If the content of zinc white is too high, the silane crosslinking of the resin is inhibited, and the strength during heat treatment is reduced.

[0076] The content of the alkylphenol formaldehyde resin is 1.5 to 15 parts by mass, preferably 1.5 to 10 parts by mass, and more preferably 2 to 10 parts by mass, based on 100 parts by mass of the elastomer having a polyisobutylene skeleton. If the content of the alkylphenol formaldehyde resin is too small, the dynamic crosslinking of the elastomer is insufficient, and the strength during heat treatment is reduced. If the content of the alkylphenol formaldehyde resin is too large, the silane crosslinking of the resin is inhibited, and the strength during heat treatment is reduced.

[0077] The resin composition constituting the outer layer preferably contains a silanol condensation catalyst. By containing the silanol condensation catalyst, crosslinking of the silane-modified resin is promoted during formation of the crosslinked resin.

[0078] The silanol condensation catalyst is not limited, and examples thereof include metal organic acid salts, titanic acid esters, borates, organic amines, ammonium salts, phosphonium salts, inorganic acids, organic acids, inorganic acid esters and the like.

[0079] Examples of the metal organic acid salt include, but are not limited to, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octoate, cobalt naphthenate, lead octoate, lead naphthenate, octanoic acid, caprylic acid, iron 2-ethylhexanoate, iron octoate, and iron stearate.

[0080] The titanate is not limited, and examples thereof include tetrabutyl titanate, tetranonyl titanate, and bis(acetoacetonitrile) diisopropyl titanate.

[0081] The organic amine is not limited, and examples thereof include ethylamine, dibutylamine, hexylamine, triethanolamine, dimethylsoyamine, tetramethylguanidine, and pyridine.

[0082] The ammonium salt is not limited, and examples thereof include ammonium carbonate and tetramethylammonium hydroxide.

[0083] The phosphonium salt is not limited, and examples thereof include tetramethylphosphonium hydroxide and the like.

[0084] The inorganic acid is not limited, and examples thereof include sulfuric acid and hydrochloric acid.

[0085] The organic acid is not limited, and examples thereof include sulfonic acids such as acetic acid, stearic acid, maleic acid, toluenesulfonic acid, and alkylnaphthalenesulfonic acid. The inorganic acid ester is not limited, and examples thereof include phosphoric acid ester.

[0086] The silanol condensation catalyst is preferably a metal organic acid salt, a sulfonic acid, or a phosphoric acid ester, and more preferably a tin metal carboxylate, such as dioctyltin dilaurate, alkylnaphthalenesulfonic acid, or ethylhexyl phosphate. In addition, the silanol condensation catalyst may be used alone or in combination of two or more.

[0087] The content of the silanol condensation catalyst is not particularly limited, but is preferably 0.0001 to 0.5 parts by mass, more preferably 0.0001 to 0.3 parts by mass, based on 100 parts by mass of the silane-modified resin.

[0088] In addition, the silanol condensation catalyst is preferably used as a silanol condensation catalyst-containing masterbatch containing a resin and a silanol condensation catalyst. Resins that can be used in the silanol condensation catalyst-containing masterbatch include polyolefins, preferably polyethylene, polypropylene, and copolymers thereof.

[0089] When the silanol condensation catalyst is used as a silanol condensation catalyst-containing masterbatch containing a resin and a silanol condensation catalyst, the content of the silanol condensation catalyst in the masterbatch is not limited, but is preferably 0.1 to 5.0% by mass. In addition, a commercially available masterbatch containing a silanol condensation catalyst can be used, for example, "PZ010" manufactured by Mitsubishi Chemical Corporation can be used.

[0090] The resin composition constituting the outer layer preferably contains an antioxidant. By containing the antioxidant, the extrusion moldability when the resin composition before crosslinking is molded is excellent.

[0091] As the anti-aging agent, there is no limitation, and examples thereof include hindered phenol antioxidants, phenol antioxidants, amine antioxidants, phosphorus heat stabilizers, metal deactivators, sulfur heat stabilizers, etc., preferably hindered phenol antioxidants, more preferably hindered phenol antioxidants containing a pentaerythritol ester structure. As a specific example of the hindered phenol antioxidant, IRGANOX (registered trademark) 1010 (pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] manufactured by BASF Japan Co., Ltd. can be cited.

[0092] The content of the antioxidant is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, and even more preferably 3 to 7 parts by mass, based on 100 parts by mass of the elastomer having a polyisobutylene skeleton.

[0093] The resin composition constituting the outer layer may contain an elastomer other than the elastomer having a polyisobutylene skeleton, a resin other than the crosslinking resin, and an additive other than the silanol condensation catalyst and the antioxidant, within a range not impairing the effects of the present invention.

[0094] The resin composition constituting the outer layer may have any phase structure, preferably a sea-island structure or a co-continuous structure, more preferably a sea-island structure consisting of a matrix (sea phase) comprising a cross-linked resin and a domain (island phase) comprising an elastomer having a polyisobutylene skeleton dispersed in the matrix.

[0095] The matrix is ​​preferably cross-linked. Cross-linking of the matrix contributes to heat resistance.

[0096] The domains are preferably cross-linked. Cross-linking of the domains contributes to heat resistance.

[0097] More preferably, both the matrix and the domains are cross-linked.

[0098] The co-continuous structure has excellent flexibility.

[0099] The water vapor permeability of the resin composition constituting the outer layer is 3.0 g·mm / (m 2 ·24h) or less, preferably 2.5g·mm / (m 2 ·24h) or less, more preferably 2.0g·mm / (m 2 24h) or less.

[0100] If the water vapor permeability is too high, moisture in the outside air penetrates into the refrigerant transport hose, causing water to freeze inside the air conditioner. The present invention effectively blocks the intrusion of moisture from the outside by using a material that is difficult to permeate water vapor as the material constituting the outer layer.

[0101] The water vapor permeability coefficient is defined as follows: The water vapor permeability coefficient is the value of the water vapor permeability coefficient per 1m under specified temperature and humidity conditions. 2 The amount of water vapor that permeates an area with a thickness of 1 mm in 24 hours.

[0102] The water vapor transmission rate was measured using a water vapor transmission tester under the conditions of a temperature of 60° C. and a relative humidity of 95%.

[0103] The breaking strength TB of the resin composition constituting the outer layer at 150°C 150 In order to make the breaking strength TB of the resin composition at 150°C 150 Within the above numerical range, the degree of crosslinking of the rubber is important.

[0104] The breaking strength can be measured in accordance with the measuring method specified in JIS K6251 "Rubber, vulcanized and thermoplastic rubber-Methods for determining tensile properties".

[0105] There is no limitation on the reinforcing layer, and it may be a woven fiber layer, for example.

[0106] The reinforcing layer is not limited, but preferably contains polyester fiber, polyamide fiber, aramid fiber, PBO fiber, vinylon fiber or rayon fiber.

[0107] There is no limitation on the inner layer, but it is preferably formed from a thermoplastic resin composition containing 100 parts by mass of an elastomer and 30 to 170 parts by mass of a thermoplastic resin, the thermoplastic resin composition having an island structure in which the elastomer exists as a structural domain in a matrix containing a thermoplastic resin, the thermoplastic resin containing 50 to 100 parts by mass of a polyamide based on 100 parts by mass of the thermoplastic resin, the elastomer containing an elastomer having a polyisobutylene skeleton, and the thermoplastic resin composition further containing a phenylenediamine-based or quinoline-based antioxidant and a processing aid.

[0108] Regarding the thermoplastic resin composition constituting the inner layer, the thermoplastic resin constituting the matrix is ​​not limited, but preferably contains 50 to 100 parts by mass of polyamide based on 100 parts by mass of the thermoplastic resin, more preferably contains 75 to 100 parts by mass of polyamide based on 100 parts by mass of the thermoplastic resin, and further preferably contains 95 to 100 parts by mass of polyamide based on 100 parts by mass of the thermoplastic resin. By containing polyamide within the above numerical range, gas barrier properties can be ensured.

[0109] Examples of the polyamide include nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 6 / 66 copolymer, nylon 6 / 12 copolymer, nylon 46, nylon 6T, nylon 9T, and nylon MXD6. Among them, nylon 6 and nylon 6 / 12 copolymer are preferred.

[0110] The thermoplastic resin composition constituting the inner layer may contain a resin other than polyamide as a thermoplastic resin constituting the matrix. The resin other than polyamide is not limited, and examples thereof include polyester, polyvinyl alcohol, and polyketone.

[0111] Regarding the thermoplastic resin composition constituting the inner layer, the elastomer constituting the domain thereof includes an elastomer having a polyisobutylene skeleton. The elastomer having a polyisobutylene skeleton is as described above.

[0112] The content of the thermoplastic resin in the thermoplastic resin composition constituting the inner layer is preferably 30 to 170 parts by mass, more preferably 35 to 169 parts by mass, and further preferably 40 to 100 parts by mass, based on 100 parts by mass of the elastomer in the thermoplastic resin composition constituting the inner layer. By making the content of the elastomer within the above numerical range, it is possible to ensure that the elastomer has a dispersed form of a sea-island structure in which the structural domain is formed, thereby ensuring flexibility and gas barrier properties.

[0113] The thermoplastic resin composition constituting the inner layer preferably contains a phenylenediamine-based or quinoline-based antioxidant. When the thermoplastic resin composition contains a phenylenediamine-based or quinoline-based antioxidant, heat aging resistance is improved.

[0114] The phenylenediamine antioxidant refers to an antioxidant having an aromatic ring in its molecular structure, wherein the aromatic ring has two secondary amines as substituents, and is preferably selected from at least one of N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, N-phenyl-N'-(1-methylheptyl)-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine and N,N'-diphenyl-p-phenylenediamine, and more preferably N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine.

[0115] The quinoline antioxidant refers to an antioxidant having a quinoline skeleton in its molecular structure, and is preferably a 2,2,4-trimethyl-1,2-dihydroquinoline polymer.

[0116] The content of the phenylenediamine antioxidant or the quinoline antioxidant in the thermoplastic resin composition constituting the inner layer (when containing both the phenylenediamine antioxidant and the quinoline antioxidant, it is the sum of the content of the phenylenediamine antioxidant and the content of the quinoline antioxidant) is preferably 0.1 to 10 parts by mass, and more preferably 0.1 to 5.0 parts by mass, based on 100 parts by mass of the total amount of the thermoplastic resin and the elastomer.

[0117] The thermoplastic resin composition constituting the inner layer preferably contains a processing aid. The processing aid contributes to improving the extrusion processability of the thermoplastic resin composition.

[0118] The processing aid is not particularly limited, but is preferably at least one selected from the group consisting of fatty acids, fatty acid metal salts, fatty acid esters, and fatty acid amides.

[0119] Examples of the fatty acid include stearic acid, palmitic acid, lauric acid, oleic acid, and linoleic acid, and stearic acid is preferred.

[0120] Examples of the fatty acid metal salt include calcium stearate, potassium stearate, zinc stearate, magnesium stearate, sodium stearate, and the like, and calcium stearate is preferred.

[0121] Examples of the fatty acid ester include glyceryl monostearate, sorbitan stearate, stearoyl stearate, and ethylene glycol distearate.

[0122] Examples of the fatty acid amide include stearic acid monoamide, oleic acid monoamide, and ethylene bisstearic acid amide.

[0123] The content of the processing aid in the thermoplastic resin composition constituting the inner layer is preferably 0.2 to 10 parts by mass, more preferably 1 to 8 parts by mass, and even more preferably 1 to 5 parts by mass, based on 100 parts by mass of the total amount of the thermoplastic resin and the elastomer.

[0124] The thermoplastic resin composition constituting the inner layer preferably contains a viscosity stabilizer. By containing a viscosity stabilizer, the increase in viscosity can be suppressed when the thermoplastic resin composition is extruded, and the generation of stagnation can be effectively reduced, thereby improving processability.

[0125] Examples of the viscosity stabilizer include divalent metal oxides, ammonium salts, carboxylates, and the like.

[0126] Examples of the divalent metal oxide include zinc oxide, magnesium oxide, copper oxide, calcium oxide, and iron oxide. Zinc oxide or magnesium oxide is preferred, and zinc oxide is more preferred.

[0127] Examples of the ammonium salt include ammonium carbonate, ammonium hydrogen carbonate, ammonium chloride, ammonium bromide, ammonium sulfate, ammonium nitrate, ammonium acetate, and alkylammonium.

[0128] Examples of the carboxylate salt include sodium acetate, potassium acetate, zinc acetate, copper acetate, sodium oxalate, ammonium oxalate, calcium oxalate, and iron oxalate.

[0129] The viscosity stabilizer is most preferably zinc oxide.

[0130] The content of the viscosity stabilizer in the thermoplastic resin composition constituting the inner layer is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 0.5 to 5 parts by mass based on 100 parts by mass of the total amount of the thermoplastic resin and the elastomer.

[0131] The matrix preferably contains 50% by mass or more of a viscosity stabilizer. When the matrix contains 50% by mass or more of a viscosity stabilizer, the viscosity increase can be suppressed during extrusion molding of the thermoplastic resin composition, and the generation of stagnation can be effectively reduced, thereby improving processability.

[0132] The thermoplastic resin composition constituting the inner layer may contain various additives in addition to the above-mentioned components.

[0133] The method for manufacturing the refrigerant transport hose is not particularly limited, and the hose can be manufactured as follows: First, an inner layer is extruded into a tube by extrusion molding, and then fibers as a reinforcement layer are woven on the tube, and then an outer layer is coated on the fibers by extrusion molding.

[0134] The method for manufacturing a hose for transporting refrigerant of the present invention preferably includes: a step of melt-kneading an elastomer having a polyisobutylene skeleton, a cross-linking resin, and a cross-linking agent for the elastomer having a polyisobutylene skeleton to prepare an outer layer composition, and a step of adding a silanol condensation catalyst to the outer layer composition during extrusion molding of the hose, and extruding the composition to which the silanol condensation catalyst was added to form an outer layer.

[0135] The crosslinkable resin refers to a resin before crosslinking of the crosslinkable resin. The crosslinkable resin is preferably the silane-modified resin.

[0136] The step of melt-kneading the elastomer having a polyisobutylene skeleton, the crosslinkable resin, and the crosslinking agent for the elastomer having a polyisobutylene skeleton to prepare the outer layer composition is hereinafter also referred to as simply a "melt-kneading step".

[0137] The melt kneading is not limited and can be carried out using a kneader, a single-screw or double-screw kneading extruder, or the like.

[0138] The temperature for melt kneading is not limited as long as melt kneading can be performed, but is preferably 170 to 240°C.

[0139] The melt-kneading time is not limited as long as the target kneaded product can be prepared, but is preferably 2 to 10 minutes.

[0140] In the melt kneading step, the elastomer having a polyisobutylene skeleton, the crosslinkable resin, the crosslinking agent for the elastomer having a polyisobutylene skeleton, and various additives such as an antioxidant, a processing aid, and a viscosity stabilizer as required are put into a kneader and melt kneaded.

[0141] However, it is preferred that the silanol condensation catalyst is not added in the melt-kneading step. When the silanol condensation catalyst is added in the melt-kneading step, when the outer layer composition prepared in the melt-kneading step comes into contact with water vapor in the atmosphere, the crosslinkable resin in the outer layer composition gradually crosslinks, and the crosslinked outer layer composition becomes difficult to shape. Therefore, the silanol condensation catalyst is preferably added to the outer layer composition during shaping.

[0142] The step of adding a silanol condensation catalyst to the outer layer composition during hose extrusion molding and extruding the composition to which the silanol condensation catalyst has been added to form the outer layer is hereinafter also referred to as "outer layer forming step".

[0143] The term "at the time of extrusion molding" means at the same time as extrusion molding or within 6 hours before extrusion molding.

[0144] The extrusion molding is not limited and can be carried out using a kneading extruder, preferably a twin-screw kneading extruder.

[0145] The silanol condensation catalyst may be added to the outer layer composition before being fed into the kneading extruder, the outer layer composition and the silanol condensation catalyst may be fed into the kneading extruder simultaneously, or the outer layer composition and the silanol condensation catalyst may be fed into separate feed ports of the kneading extruder.

[0146] The silanol condensation catalyst itself may be directly added to the outer layer composition, but is preferably added as a masterbatch containing the silanol condensation catalyst in which the resin and the silanol condensation catalyst are blended.

[0147] The composition to which the silanol condensation catalyst is added is extruded onto the outer surface of the reinforcing layer to form an outer layer.

[0148] The conditions for extrusion molding are not limited as long as the outer layer can be formed.

[0149] The method for manufacturing a hose for transporting a refrigerant of the present invention preferably includes: after the outer layer forming step, bringing the outer layer into contact with water or water vapor to crosslink the matrix in the resin composition constituting the outer layer (hereinafter also referred to as "water contact step"). By implementing the water contact step, the crosslinkable resin in the resin composition constituting the outer layer is crosslinked, and the heat resistance of the outer layer is improved.

[0150] When the outer layer formed by the outer layer forming step comes into contact with water vapor in the atmosphere, the crosslinkable resin in the outer layer gradually crosslinks to generate a crosslinked resin, and the outer layer is crosslinked. When it is desired to rapidly crosslink the outer layer, it is preferred to perform the water contact step.

[0151] There is no limitation on the method of contacting with water or water vapor, and examples thereof include immersion in a water bath, spraying water, and placing in an atmosphere containing water vapor. Preferably, the method is placing in an atmosphere containing water vapor. In the method of placing in an atmosphere containing water vapor, the temperature is room temperature to 200° C., preferably room temperature to 100° C., and the relative humidity is 30 to 100%, preferably 40 to 90%, and the mixture is allowed to stand for 1 minute to 1 month, preferably 1 hour to 1 week, and more preferably 1 to 4 days in air at a temperature of 25° C. and a relative humidity of 50%. More specifically, the mixture is preferably allowed to stand for 72 hours or more in air at a temperature of 25° C. and a relative humidity of 50%.

[0152] When the cross-linkable resin is a silane-modified resin, the hydrolyzable silyl groups (preferably alkoxysilyl groups) of the silane-modified resin in the outer layer are hydrolyzed to generate silanol groups through the water contact step, and the silanol groups undergo a condensation reaction to form siloxane bonds (Si—O—Si) and cross-link to obtain a cross-linked outer layer.

[0153] Example

[0154] [raw materials]

[0155] The raw materials used in the following Examples and Comparative Examples are as follows.

[0156] (Raw materials for outer layer)

[0157] IIR: ExxonMobil Chemical Company butyl rubber "Exxon Butyl" 268

[0158] Br-IIR: Exxon Bromobutyl 2255, manufactured by ExxonMobil Chemical Company

[0159] Cross-linking resin: Silane-modified polypropylene "Linklon" (registered trademark) XPM800HM manufactured by Mitsubishi Chemical Corporation

[0160] Polypropylene: Prime Polymer Co., Ltd. propylene homopolymer "Prime Polymer" (registered trademark) J108M

[0161] PP / EPDM: PP / EPDM thermoplastic elastomer "Santoprene" (registered trademark) 111-35 manufactured by ExxonMobil Japan Corporation

[0162] Resin-based crosslinking agent-1: Alkylphenol formaldehyde resin "Hitanol" (registered trademark) 2501Y manufactured by Hitachi Chemical Co., Ltd.

[0163] Resin-based crosslinking agent-2: Brominated alkylphenol formaldehyde resin "Tackirol" (registered trademark) 250-I manufactured by Taoka Chemical Industry Co., Ltd.

[0164] Zinc white: 3 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.

[0165] Silanol condensation catalyst: Mitsubishi Chemical Corporation's silane crosslinking agent masterbatch "Catalyst MB" PZ010

[0166] Anti-aging agent-1: Hindered phenol-based anti-aging agent "IRGANOX" (registered trademark) 1010 manufactured by BASF Japan Co., Ltd.

[0167] (Raw materials for inner layer)

[0168] Butyl rubber: ExxonMobil Chemical Company's brominated isobutylene-p-methylstyrene copolymer rubber "EXXPRO" (registered trademark) 3745

[0169] Nylon 6: Nylon 6 "UBE Nylon" (registered trademark) 1011FB manufactured by Ube Industries, Ltd.

[0170] Nylon 6 / 12: Nylon 6 / 12 copolymer "UBE Nylon" (registered trademark) 7024B manufactured by Ube Industries, Ltd.

[0171] Anti-aging agent-2: Phenylenediamine antioxidant "SANTOFLEX" (registered trademark) 6PPD manufactured by Solutia (substance name: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine)

[0172] Viscosity stabilizer: 3 types of zinc oxide manufactured by Shodo Chemical Industry Co., Ltd.

[0173] Processing aid-1: Industrial stearic acid manufactured by Chiba Fatty Acid Co., Ltd.

[0174] Processing aid-2: Calcium stearate SC-PG manufactured by Sakai Chemical Industry Co., Ltd.

[0175] [Preparation of outer layer resin composition]

[0176] The outer layer resin compositions A1 to A11, A'1 and A'2 are prepared by the following method. The raw materials except the silanol condensation catalyst are put into a twin-screw kneading extruder (manufactured by Nippon Steel Works, Ltd.) in the mixing ratio shown in Table 1, and kneaded at 235°C for 3 minutes. The kneaded material is continuously extruded from the extruder into a strand shape, and cut with a cutter after water cooling, thereby obtaining granular outer layer resin compositions A1 to A11, A'1 and A'2. When measuring and evaluating the water vapor permeability, flexibility, extrusion processability and breaking strength, the silanol condensation catalyst is added when the sheet is formed by the extruder, and when the hose for refrigerant transportation is made, the silanol condensation catalyst is added during the tubular extrusion of the outer layer resin composition.

[0177] As the outer layer resin composition A'3, commercially available PP / EPDM thermoplastic elastomer "Santoprene" (registered trademark) 111-35 (a thermoplastic elastomer having a matrix of polypropylene and a domain of ethylene-propylene-diene copolymer) was used.

[0178] The water vapor transmission rate, flexibility, extrusion processability and breaking strength TB at 150° C. of the outer layer resin compositions A1 to A11 and A′1 to A′3 were measured and evaluated. 150 The measurement and evaluation results are shown in Table 1.

[0179] [Preparation of the thermoplastic resin composition for inner layer]

[0180] The raw materials were fed into a twin-screw kneading extruder (manufactured by The Nippon Steel Works, Ltd.) at the mixing ratios shown in Table 2 and kneaded for 3 minutes at 235° C. The kneaded product was continuously extruded from the extruder into a strand, water-cooled, and cut with a cutter to obtain pelletized thermoplastic resin compositions B1 to B4 for the inner layer.

[0181] [Manufacturing of hose for refrigerant transportation]

[0182] On a mandrel pre-coated with a release agent, the inner layer thermoplastic resin composition was extruded into a tube having a thickness shown in Tables 3 to 5 by an extruder. A polyester reinforcing yarn was braided thereon using a braiding machine, and on the outer layer resin composition to which a silanol condensation catalyst was added was extruded into a tube having a thickness shown in Tables 3 to 5 by an extruder, and the mandrel was pulled out, thereby producing a hose consisting of an inner layer / reinforcement layer / outer layer.

[0183] The produced hose was left to stand in air at 25°C and 50% relative humidity for 72 hours or more to crosslink the outer layer resin composition, and then evaluated for heat resistance, water permeation resistance, refrigerant permeation resistance, and flexibility. The evaluation results are shown in Tables 3 to 5.

[0184] The measurement and evaluation methods are as follows.

[0185] [Measurement of water vapor transmission rate]

[0186] Using a 40 mm φ single-screw extruder (Pla Technology Co., Ltd.) with a 550 mm wide T-die, the temperature of the barrel and the die was set to the melting point of the polymer component with the highest melting point in the sample composition + 10°C, and the sample of the outer layer resin composition to which the silanol condensation catalyst was added was formed into a sheet with an average thickness of 0.2 mm under the conditions of a cooling roll temperature of 50°C and a pulling speed of 3 m / min. The prepared sheet was left to stand in air at a temperature of 25°C and a relative humidity of 50% for more than 72 hours to prepare a sheet of a cross-linked resin composition.

[0187] The obtained sheet was cut out, and the water vapor transmission rate was measured at a temperature of 60° C. and a relative humidity of 95% using a water vapor transmission tester manufactured by GTR Tec Co., Ltd.

[0188] [Evaluation of Flexibility of Outer Layer Resin Composition]

[0189] The cross-linked sheet with an average thickness of 0.2 mm produced in the measurement of water vapor transmission rate was punched into a JIS No. 3 dumbbell shape, and a tensile test was carried out at a temperature of 25°C and a speed of 500 mm / min based on the measurement method specified in JIS K6251 "Rubber, vulcanized and thermoplastic rubber - Method for determining tensile properties". The stress at 10% elongation (10% modulus) was calculated from the obtained stress-strain curve.

[0190] The 10% modulus is an index of flexibility. The smaller the 10% modulus, the better the flexibility. The flexibility was evaluated as ○ when the 10% modulus was 10 MPa or less, and was evaluated as × when the 10% modulus exceeded 10 MPa.

[0191] [Evaluation of extrusion processability]

[0192] Using a 40mmφ single-screw extruder with a 550mm wide T-die (Pla Technology Co., Ltd.), the temperature of the barrel and die was set to the melting point of the polymer component with the highest melting point in the sample composition + 10°C, and the sample of the outer layer resin composition added with a silanol condensation catalyst was molded into a sheet with an average thickness of 0.2mm under the conditions of a cooling roller temperature of 50°C and a pulling speed of 3m / min. The situation where molding could be carried out without problems was evaluated as ○, the situation where slight particles, openings or breaks at the ends of the sheet were evaluated as △, and the situation where serious particles, openings or breaks at the ends of the sheet were evaluated as ×.

[0193] [Determination of breaking strength]

[0194] The sheet with an average thickness of 0.2 mm produced in the measurement of water vapor transmission rate was left to stand in air at a temperature of 25°C and a relative humidity of 50% for more than 72 hours to produce a sheet of a cross-linked resin composition. The sheet of the cross-linked resin composition was punched into a JIS No. 3 dumbbell shape, and a tensile test was performed at a temperature of 150°C and a speed of 500 mm / min based on the measurement method specified in JIS K6251 "Vulcanized rubber and thermoplastic rubber-Method for determining tensile properties". The stress at break was determined from the obtained stress-strain curve and was taken as the breaking strength TB at 150°C. 150 .

[0195] [Evaluation of heat resistance]

[0196] The test sample placed in an oven at 150°C for 240 hours was pressurized to an internal pressure of 3.5 MPa and kept for 5 minutes to confirm the sealing of the riveted part after heat aging. The case of no leakage was evaluated as ○, and the case of leakage was evaluated as ×.

[0197] [Evaluation of moisture permeability resistance]

[0198] Each test sample was placed in an oven at 50°C for 5 hours, and a desiccant volume equivalent to 80% of the internal volume of the test sample was filled into the test sample and sealed. The test sample was placed in an atmosphere of temperature 50°C and relative humidity 95%, and the mass increase of the desiccant after 120 hours to 360 hours was measured. The mass increase after 240 hours was divided by the internal surface area of ​​the test sample to calculate the water vapor permeability coefficient [mg / (240h·cm 2 )]. The smaller the value of the water vapor permeability coefficient, the better the water permeability resistance. If the value is 3 or less, it can be evaluated as having sufficient water permeability resistance for practical use. In Tables 3 to 5, the case where the value is 3 or less is evaluated as ○, and the case where the value exceeds 3 is evaluated as ×.

[0199] [Evaluation of refrigerant permeation resistance]

[0200] The measurement was performed based on SAE J2064 AUG2015. In each test sample with a length of 1.07 m, every 1 cm 3 The internal volume of the test sample is filled with 70% ± 3% of refrigerant (HFO-1234yf). The test sample is placed in an atmosphere of 80°C for 25 days, and the mass reduction (refrigerant permeation) [kg / day] per day during the last predetermined period (5 to 7 days) of the 25-day period is measured. The value obtained by dividing the reduction by the internal surface area of ​​the test sample is converted into a value per year, and the refrigerant permeation coefficient [kg / (m 2 ·year)]. The smaller the value of the refrigerant permeability coefficient, the better the refrigerant permeability resistance. If the value is 3 or less, it can be evaluated as having practically sufficient refrigerant permeability resistance. In Tables 3 to 5, the case where the value is 3 or less is evaluated as ○, and the case where the value exceeds 3 is evaluated as ×.

[0201] [Evaluation of the flexibility of the hose]

[0202] like Figure 2 As shown, for each test sample S, one end in the length direction is fixed by a fixing tool such as a clamp, and a spring balance is installed and stretched at the other end which is away from the fixed position by a predetermined length L (120 + hose outer diameter / 2) × π [mm], so that the test sample S is bent in a semicircular arc shape from the state shown by the dotted line to the state shown by the solid line. In addition, the tensile force F measured by the spring balance stretched in the horizontal direction in the bent state with the inner radius R of the hose being 120 mm is used as an evaluation index. The smaller the value of the tensile force F, the easier the test sample S is to bend and the better the flexibility. If the tensile force F is less than 20N, it can be evaluated as having sufficient flexibility for practical use. In Tables 3 to 5, the case where the tensile force F is less than 20N is evaluated as ○, and the case where the tensile force F exceeds 20N is evaluated as ×.

[0203] [Table 1]

[0204]

[0205] [Table 2]

[0206] Table 2 Composition of the thermoplastic resin composition for the inner layer

[0207]

[0208] [Table 3]

[0209]

[0210] [Table 4]

[0211]

[0212] [Table 5]

[0213]

[0214] Industrial Availability

[0215] The refrigerant transport hose of the present invention can be preferably used to transport refrigerant for air conditioners of automobiles and the like.

[0216] Description of Reference Numerals

[0217] 1Refrigerant delivery hose

[0218] 2Inner layer

[0219] 3 Strengthening layer

[0220] 4 Outer Layer

[0221] F tensile force

[0222] LPredetermined length

[0223] R Hose inner radius

[0224] S test sample

Claims

1. A hose for transporting a refrigerant, comprising an outer layer, a reinforcing layer and an inner layer, wherein the outer layer is composed of a resin composition, the resin composition comprising 100 parts by mass of an elastomer having a polyisobutylene skeleton, 10 to 150 parts by mass of a cross-linking resin and 2.5 to 25 parts by mass of a cross-linking agent for the elastomer having a polyisobutylene skeleton, and the water vapor permeability of the resin composition constituting the outer layer is 3.0 g·mm / (m 2 24h) or less.

2. The refrigerant transport hose according to claim 1, wherein the crosslinking agent of the elastomer having a polyisobutylene skeleton contains zinc white and an alkylphenol formaldehyde resin.

3. The refrigerant transport hose according to claim 1 or 2, wherein in the resin composition constituting the outer layer, the content of zinc white is 1 to 10 parts by mass based on 100 parts by mass of the elastomer having a polyisobutylene skeleton, and the content of alkylphenol formaldehyde-based resin is 1.5 to 15 parts by mass based on 100 parts by mass of the elastomer having a polyisobutylene skeleton.

4. The refrigerant transport hose according to any one of claims 1 to 3, wherein the elastomer having a polyisobutylene skeleton in the resin composition constituting the outer layer is butyl rubber or modified butyl rubber, and the elastomer having a polyisobutylene skeleton is dynamically crosslinked.

5. The refrigerant transport hose according to any one of claims 1 to 4, wherein the crosslinked resin in the resin composition constituting the outer layer is a silane-modified resin obtained by crosslinking a thermoplastic resin modified with a silane compound.

6. The refrigerant transport hose according to any one of claims 1 to 5, wherein the crosslinked resin in the resin composition constituting the outer layer is a crosslinked silane-modified polyolefin obtained by modifying a polyolefin with a silane compound.

7. The refrigerant transport hose according to any one of claims 1 to 6, wherein the crosslinked resin in the resin composition constituting the outer layer is a crosslinked silane-modified polypropylene obtained by modifying polypropylene with a silane compound. 8 . The refrigerant transport hose according to claim 1 , wherein the resin composition constituting the outer layer contains 1 to 10 parts by mass of an antioxidant based on 100 parts by mass of the elastomer having a polyisobutylene skeleton.

9. The refrigerant transport hose according to any one of claims 1 to 8, wherein the resin composition constituting the outer layer has a breaking strength TB at 150°C. 150 It is above 1.0MPa.

10. The refrigerant transport hose according to any one of claims 1 to 9, wherein the resin composition constituting the outer layer comprises a matrix containing a crosslinked resin and domains containing an elastomer having a polyisobutylene skeleton dispersed in the matrix, and the matrix is ​​crosslinked.

11. The refrigerant transport hose according to any one of claims 1 to 10, wherein the resin composition constituting the outer layer comprises a matrix containing a crosslinked resin and domains containing an elastomer having a polyisobutylene skeleton dispersed in the matrix, and the domains are crosslinked.

12. A refrigerant transport hose according to any one of claims 1 to 11, wherein the inner layer is composed of a thermoplastic resin composition containing 100 parts by mass of an elastomer and 30 to 170 parts by mass of a thermoplastic resin, the thermoplastic resin composition having a sea-island structure in which the elastomer exists as a structural domain in a matrix containing the thermoplastic resin, the thermoplastic resin contains 50 to 100 parts by mass of a polyamide based on 100 parts by mass of the thermoplastic resin, the elastomer includes an elastomer having a polyisobutylene skeleton, and the thermoplastic resin composition further contains a processing aid and a phenylenediamine-based or quinoline-based antioxidant.

13. A method for manufacturing the refrigerant transport hose according to any one of claims 1 to 12, the method comprising: The invention also provides a process of preparing an outer layer composition by melt-kneading an elastomer having a polyisobutylene skeleton, a cross-linking resin and a cross-linking agent for the elastomer having a polyisobutylene skeleton, and a process of adding a silanol condensation catalyst to the outer layer composition during hose extrusion molding, and extruding the composition to which the silanol condensation catalyst has been added to form an outer layer.

14. The method according to claim 13, further comprising, after the step of forming the outer layer, bringing the outer layer into contact with water or water vapor to crosslink the matrix in the resin composition constituting the outer layer.

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