Hose for refrigerant transfer and method for manufacturing the same

Abstract

The present invention provides a refrigerant delivery hose having excellent flexibility, water vapor barrier properties, and heat resistance. A refrigerant delivery hose comprising an outer layer, a reinforcing layer, and an inner layer, characterized in that the outer layer is formed of a resin composition containing an elastomer having a polyisobutylene backbone and a crosslinked resin, the content of the elastomer having a polyisobutylene backbone in the resin composition is 30% by mass or more and 90% by mass or less based on the mass of the resin composition, the content of the crosslinked resin in the resin composition is 10% by mass or more and 70% by mass or less based on the mass of the resin composition, the water vapor permeability of the resin composition is 2.0 g·mm / (m 2 ·24 h) or less, and the breaking strength TB of the resin composition at 100 °C 100 and the breaking strength TB at 25 °C 25 ratio TB 100 / TB 25 is 0.2 to 1.0.

Description

Technical Field

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

[0002] Among the increasing requirements for vehicle weight reduction, there have been efforts to replace rubber, which has been used for automotive hoses, with a resin having high barrier properties and to achieve weight reduction by thinning the wall thickness. In particular, since the main material of the refrigerant transfer hose for an existing automotive air conditioner is rubber, if this main material can be replaced with a resin having high barrier properties, weight reduction can be achieved.

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

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Laid-Open No. 4-145284 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] Since an automotive air conditioner, etc. is mounted in a limited and narrow space in an automobile, the refrigerant transfer hose is required to have excellent flexibility and be easily installed even in a narrow space. In addition, since the penetration of water vapor from the outside of the hose causes freezing of moisture inside the air conditioner, the material forming the outer tube of the refrigerant transfer hose is required to have excellent water vapor barrier properties. Furthermore, durability to withstand long-term use in a high-temperature and high-humidity environment in the engine room is also required.

[0009] 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, its heat resistance is not necessarily sufficient.

[0010] An object of the present invention is to provide a refrigerant transfer hose having excellent flexibility, water vapor barrier properties, and heat resistance.

[0011] Means for Solving the Problems

[0012] The present invention (I) is a refrigerant delivery hose including an outer layer, a reinforcing layer, and an inner layer, characterized in that the outer layer is formed of a resin composition containing an elastomer having a polyisobutylene backbone and a crosslinked resin, the content of the elastomer having a polyisobutylene backbone in the resin composition is 30% by mass or more and 90% by mass or less based on the mass of the resin composition, the content of the crosslinked resin in the resin composition is 10% by mass or more and 70% by mass or less based on the mass of the resin composition, the water vapor transmission rate of the resin composition is 2.0 g·mm / (m 2 ·24 h) or less, and the breaking strength TB of the resin composition at 100 °C 100 and the breaking strength TB at 25 °C 25 are in a ratio TB 100 / TB 25 of 0.2 to 1.0.

[0013] The present invention (II) is a method for manufacturing the refrigerant delivery hose of the present invention (I), characterized in that the method includes the following steps: a step of melt-kneading an elastomer having a polyisobutylene backbone and a crosslinkable resin to prepare a composition for the outer layer, and a step of adding a silanol condensation catalyst to the composition for the outer layer during the extrusion molding of the hose and extruding the composition added with the silanol condensation catalyst to form the outer layer.

[0014] The present invention includes the following embodiments.

[0015] [1] A refrigerant delivery hose, which is a refrigerant delivery hose including an outer layer, a reinforcing layer, and an inner layer, wherein the outer layer is formed of a resin composition containing an elastomer having a polyisobutylene backbone and a crosslinked resin, the content of the elastomer having a polyisobutylene backbone in the resin composition is 30% by mass or more and 90% by mass or less based on the mass of the resin composition, the content of the crosslinked resin in the resin composition is 10% by mass or more and 70% by mass or less based on the mass of the resin composition, the water vapor transmission rate of the resin composition is 2.0 g·mm / (m 2 ·24 h) or less, and the breaking strength TB of the resin composition at 100 °C 100 and the breaking strength TB at 25 °C 25 are in a ratio TB 100 / TB 25 of 0.2 to 1.0.

[0016] [2] The refrigerant delivery hose according to [1], wherein the crosslinked resin is a resin obtained by modifying a thermoplastic resin with a silane compound and crosslinking the obtained silane-modified resin.

[0017] [3] The refrigerant delivery hose according to [2], wherein the crosslinked resin is a resin obtained by modifying a polyolefin with a silane compound and crosslinking the resulting silane-modified polyolefin.

[0018] [4] The refrigerant delivery hose according to [3], wherein the crosslinked resin is a resin obtained by modifying a polypropylene with a silane compound and crosslinking the resulting silane-modified polypropylene.

[0019] [5] The refrigerant delivery hose according to any one of [1] to [4], wherein the elastomer having a polyisobutylene backbone is butyl rubber or modified butyl rubber, and the elastomer having a polyisobutylene backbone is dynamically crosslinked.

[0020] [6] The refrigerant delivery hose according to any one of [1] to [5], wherein the resin composition contains an anti-aging agent in an amount of 1% by mass or more and 4% by mass or less based on the mass of the resin composition.

[0021] [7] The refrigerant delivery hose according to any one of [1] to [6], wherein the inner layer is formed of a thermoplastic resin composition, and the thermoplastic resin composition has a sea-island structure in which an elastomer exists in the form of domains in a matrix containing a thermoplastic resin. The thermoplastic resin contains 50% by mass or more and 100% by mass or less of polyamide based on the mass of the thermoplastic resin. The elastomer contains an elastomer having a polyisobutylene backbone, and the content of the elastomer is 30% by mass or more and 80% by mass or less based on the mass of the thermoplastic resin composition. The thermoplastic resin composition further contains a phenylenediamine-based or quinoline-based anti-aging agent and a processing aid.

[0022] [8] The refrigerant delivery hose according to any one of [1] to [7], wherein the reinforcing layer contains polyester fiber, polyamide fiber, aromatic polyamide fiber, PBO fiber, vinylon fiber, or rayon fiber.

[0023] [9] A method for manufacturing the refrigerant delivery hose according to any one of [1] to [8], the method comprising the steps of: melting and kneading an elastomer having a polyisobutylene backbone and a crosslinkable resin to prepare an outer layer composition; and adding a silanol condensation catalyst to the outer layer composition during hose extrusion molding and extruding the composition added with the silanol condensation catalyst to form an outer layer.

[0024]

[10] The method according to [9], wherein the crosslinkable resin is a silane-modified resin obtained by modifying a thermoplastic resin with a silane compound.

[0025] Advantages of the Invention

[0026] The refrigerant transfer hose of the present invention is excellent in flexibility, water vapor barrier property, and heat resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a cross-sectional view of the refrigerant transfer hose.

[0028] Figure 2 It is a view showing an evaluation method of the flexibility of the hose. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention (I) relates to a refrigerant transfer hose.

[0030] The refrigerant transfer hose refers to a hose for transferring refrigerants for air conditioners and the like. The refrigerant transfer hose of the present invention is particularly suitable for use as a hose for transferring refrigerants for automotive air conditioners. Examples of refrigerants for air conditioners include hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), hydrocarbons, carbon dioxide, ammonia, water, etc. Examples of HFCs include R410A, R32, R404A, R407C, R507A, R134a, etc. Examples of HFOs include R1234yf, R1234ze, 1233zd, R1123, R1224yd, R1336mzz, etc. Examples of hydrocarbons include methane, ethane, propane, propylene, butane, isobutane, hexafluoropropane, pentane, etc.

[0031] The refrigerant transfer hose of the present invention includes an outer layer, a reinforcing layer, and an inner layer.

[0032] Figure 1 The cross-section of one embodiment of the refrigerant transfer hose of the present invention is shown in the figure. However, the present invention is not limited to Figure 1 the structure shown.

[0033] The refrigerant transfer hose 1 includes an inner layer 2, a reinforcing layer 3 disposed outside the inner layer 2, and an outer layer 4 disposed outside the reinforcing layer 3.

[0034] The outer layer is formed of a resin composition containing an elastomer having a polyisobutylene skeleton and a crosslinked resin.

[0035] The elastomer having a polyisobutylene skeleton is not limited as long as it has a polyisobutylene skeleton, and butyl rubber (IIR), modified butyl rubber, and styrene-isobutylene-styrene block copolymer are preferred, and butyl rubber or modified butyl rubber is more preferred.

[0036] The polyisobutylene skeleton refers to a chemical structure formed by polymerization of a plurality of isobutylenes, that is, -[-CH 2 -C(CH 3 ) 2 -] n -(where n is an integer of 2 or more.) shown chemical structure.

[0037] Butyl rubber refers to an isobutene-isoprene copolymer obtained by copolymerizing isobutene and a small amount of isoprene, and is abbreviated as IIR.

[0038] Modified butyl rubber refers to butyl rubber having double bonds and halogens on the isoprene backbone. The modified butyl rubber is preferably a halogenated butyl rubber, more preferably a brominated butyl rubber or a chlorinated butyl rubber, and further preferably a brominated butyl rubber.

[0039] Styrene-isobutene-styrene block copolymer is abbreviated as SIBS.

[0040] By containing an elastomer having a polyisobutene backbone in the resin composition, the flexibility and water vapor barrier property of the resin composition are improved.

[0041] The elastomer having a polyisobutene backbone is preferably dynamically crosslinked. By performing dynamic crosslinking, the durability is improved.

[0042] The content of the elastomer having a polyisobutene backbone is 30% by mass or more and 90% by mass or less, preferably 40% by mass or more and 89% by mass or less, and more preferably 50% by mass or more and 88% by mass or less based on the mass of the resin composition. If the content of the elastomer having a polyisobutene backbone is too small, the flexibility cannot be ensured, and if it is too large, the extrusion processability deteriorates.

[0043] The resin composition contains a crosslinked resin. The resin composition has excellent heat resistance by containing the crosslinked resin.

[0044] The crosslinked resin refers to a resin that has been crosslinked. The crosslinked resin is not limited, and preferably a resin obtained by crosslinking a silane-modified resin. The 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 crosslinkable resin having a hydrolyzable silyl group (preferably an alkoxysilyl group) obtained by modifying a polyolefin-based thermoplastic resin with a silane compound.

[0045] That is, the crosslinked resin is preferably a resin obtained by modifying a thermoplastic resin with a silane compound and crosslinking the obtained silane-modified resin, more preferably a resin obtained by modifying a polyolefin with a silane compound and crosslinking the obtained silane-modified polyolefin, and further preferably a resin obtained by modifying polypropylene with a silane compound and crosslinking the obtained silane-modified polypropylene.

[0046] The silane compound is not limited, and preferably a compound represented by the formula (1).

[0047] R 1 -SiR2 n Y 3-n (1)

[0048] Among them, R 1 is an ethylenically unsaturated hydrocarbon group, R 2 is a hydrocarbon group, Y is a hydrolyzable organic group, and n is an integer from 0 to 2.

[0049] R 1 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, a γ-(meth)acryloyloxypropyl group, etc.

[0050] R 2 is preferably a hydrocarbon group having 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, a decyl group, a phenyl group, etc.

[0051] Y is preferably a hydrolyzable organic group having 1 to 10 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a formyloxy group, an acetyloxy group, a propionyloxy group, an alkylamino group, an arylamino group, etc.

[0052] Specific examples of the silane compound include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-(meth)acryloyloxypropyltrimethoxysilane, etc. Among these, vinyltrimethoxysilane is preferred.

[0053] The polyolefin-based thermoplastic resin constituting the silane-modified resin is not limited, and examples thereof include polyethylene, a copolymer of ethylene and an α-olefin, polypropylene, a copolymer of propylene and other α-olefins, etc. Polypropylene and a copolymer of propylene and other α-olefins are preferred, and polypropylene is particularly preferred.

[0054] The hydrolyzable silyl group means a group that can generate a silanol group (≡Si-OH) by hydrolysis, and a group represented by the formula (2) is preferred.

[0055] -SiR 2 n Y 3-n (2)

[0056] Among them, R 2 and Y are as described above.

[0057] The crosslinkable resin means a resin that can undergo a crosslinking reaction but has not yet undergone crosslinking. The type of crosslinking reaction is not limited, and it can be crosslinked by a peroxide, but crosslinking by moisture (water crosslinking) is preferred.

[0058] The method of modifying with a silane compound is not limited, and grafting or copolymerization can be cited. Grafting is a method of adding a silane compound and a resin by a graft reaction. More specifically, it is a reaction in which a carbon-hydrogen bond of a polyolefin is cleaved to generate a carbon radical, and an addition reaction is carried out with a silane compound having an ethylenically unsaturated hydrocarbon group. The modification is preferably carried out by melt-kneading the resin and the silane compound of formula (1) in the presence of a radical generator such as an organic peroxide. Copolymerization is preferably carried out by radical copolymerization of the monomers constituting the resin and the silane compound of formula (1).

[0059] The preferred silane-modified resin is a silane-modified polypropylene. There are commercially available silane-modified resins, and commercially available products can be used as the silane-modified resins used in the present invention. As commercially available products of silane-modified resins, "Linkron" (registered trademark) manufactured by Mitsubishi Chemical Corporation can be cited.

[0060] The content of the crosslinked resin is 10% by mass or more and 70% by mass or less, preferably 11% by mass or more and 60% by mass or more, more preferably 12% by mass or more and 50% by mass or less based on the mass of the resin composition. If the content of the crosslinked resin is too small, the extrusion processability deteriorates, and if it is too large, flexibility cannot be ensured.

[0061] The resin composition may contain resins other than the crosslinked resin. Examples of resins other than the crosslinked resin include polyolefin resins and polyamide resins. Examples of polyolefin resins include polypropylene. In addition to the crosslinked resin, by further containing polypropylene, the viscosity of the resin component is stabilized, so that a phase structure that easily exhibits hot strength is formed. In addition, since polypropylene has good water vapor barrier properties, the water vapor barrier properties of the entire composition are good.

[0062] When the resin composition contains a resin other than the crosslinked resin, the content of the resin other than the crosslinked resin is preferably 1% by mass or more and 60% by mass or less, more preferably 2% by mass or more and 55% by mass or less, and further preferably 3% by mass or more and 50% by mass or less based on the mass of the resin composition.

[0063] The water vapor transmission rate of the resin composition is 2.0 g·mm / (m 2 ·24 h) or less, preferably 1.9 g·mm / (m 2 ·24 h) or less.

[0064] If the water vapor transmission rate is too high, moisture in outdoor air penetrates into the refrigerant delivery hose, causing water freezing inside the air conditioner. In the present invention, by using a material that is difficult to transmit water vapor as the material constituting the outer layer, the intrusion of external moisture can be effectively blocked.

[0065] The water vapor transmission coefficient is defined as follows. The water vapor transmission coefficient is the amount of water vapor permeating through an area of 1 m 2 under a thickness of 1 mm in 24 hours under specified temperature and humidity conditions.

[0066] The water vapor permeability is measured using a water vapor permeation testing machine at a temperature of 60°C and a relative humidity of 95%.

[0067] The breaking strength TB of the resin composition at 100°C 100 and the breaking strength TB at 25°C 25 The ratio TB 100 / TB 25 is 0.2 or more and 1.0 or less, preferably 0.3 or more and 1.0 or less, more preferably 0.35 or more and 1.0 or less.

[0068] TB 100 / TB 25 The closer TB 100 / TB 25 is to 1.0, the better the heat resistance. By using a crosslinked resin, TB

[0069] The breaking strength can be measured according to the measurement method specified in JIS K6251 "Vulcanized Rubber and Thermoplastic Rubber - Method for Determining Tensile Properties".

[0070] The resin composition preferably contains a silanol condensation catalyst. By containing a silanol condensation catalyst, the crosslinking of the silane-modified resin is promoted during the formation of the crosslinked resin.

[0071] There is no limitation on the silanol condensation catalyst, and examples thereof include metal organic acid salts, titanates, borates, organic amines, ammonium salts, phosphonium salts, inorganic acids, organic acids, inorganic acid esters, etc.

[0072] There is no limitation on the metal organic acid salt, and examples thereof include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dioctanoate, stannous acetate, stannous octoate, cobalt naphthenate, lead octoate, lead naphthenate, zinc octoate, zinc decanoate, iron 2-ethylhexanoate, iron octoate, iron stearate, etc.

[0073] There is no limitation on the titanate, and examples thereof include tetrabutyl titanate, tetranonyl titanate, bis(acetylacetonitrile)di-isopropyl titanate, etc.

[0074] There is no limitation on the organic amine, and examples include ethylamine, dibutylamine, hexylamine, triethanolamine, dimethyl soya amine, tetramethylguanidine, pyridine, etc.

[0075] There is no limitation on the ammonium salt, and examples include ammonium carbonate, tetramethylammonium hydroxide, etc.

[0076] There is no limitation on the phosphonium salt, and examples include tetramethylphosphonium hydroxide, etc.

[0077] There is no limitation on the inorganic acid, and examples include sulfuric acid, hydrochloric acid, etc.

[0078] There is no limitation on the organic acid, and examples include acetic acid, stearic acid, maleic acid, sulfonic acids such as toluenesulfonic acid, alkylnaphthalenesulfonic acid, etc. There is no limitation on the inorganic acid ester, and examples include phosphate esters, etc.

[0079] The silanol condensation catalyst is preferably an organometallic acid salt, a sulfonic acid, or a phosphate ester, more preferably a metal carboxylate of tin, such as dioctyltin dilaurate, alkylnaphthalenesulfonic acid, or ethylhexyl phosphate ester. It should be noted that the silanol condensation catalyst can be used alone or in combination of two or more as appropriate.

[0080] There is no particular limitation on the content of the silanol condensation catalyst. Based on 100 parts by mass of the silane-modified resin, it is preferably 0.0001 to 0.5 part by mass, more preferably 0.0001 to 0.3 part by mass.

[0081] It should be noted that the silanol condensation catalyst is preferably used as a masterbatch containing the silanol condensation catalyst in which the resin and the silanol condensation catalyst are compounded. Examples of the resin that can be used for the masterbatch containing the silanol condensation catalyst include polyolefins, etc., and preferably polyethylene, polypropylene, their copolymers, etc.

[0082] When the silanol condensation catalyst is used as a masterbatch containing the silanol condensation catalyst in which the resin and the silanol condensation catalyst are compounded, there is no limitation on the content of the silanol condensation catalyst in the masterbatch, and it is preferably 0.1 to 5.0% by mass. It should be noted that the masterbatch containing the silanol condensation catalyst can be a commercially available product, and for example, "PZ010" manufactured by Mitsubishi Chemical Corporation can be used.

[0083] The resin composition preferably contains an anti-aging agent. By containing the anti-aging agent, the extrusion moldability during the molding of the resin composition before crosslinking becomes good.

[0084] There is no limitation on the anti-aging agent, and examples thereof include hindered phenol antioxidants, phenolic antioxidants, amine antioxidants, phosphorus-based heat stabilizers, metal deactivators, sulfur-based heat stabilizers, etc. A hindered phenol antioxidant is preferred, and a hindered phenol antioxidant containing a pentaerythritol ester structure is more preferred. As a specific example of the hindered phenol antioxidant, IRGANOX (registered trademark) 1010 (pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]) manufactured by BASF Japan Ltd. can be cited.

[0085] The content of the anti-aging agent is preferably 1% by mass or more and 4% by mass or less, more preferably 1% by mass or more and 3.5% by mass or less, based on the mass of the resin composition.

[0086] The resin composition may contain, within the range not hindering the effects of the present invention, an elastomer other than the elastomer having a polyisobutylene backbone, a resin other than the silane-modified resin, and additives other than the silanol condensation catalyst and the anti-aging agent.

[0087] The resin composition may have any phase structure, but preferably has a sea-island structure or a co-continuous structure, and more preferably has a sea-island structure formed by a matrix (sea phase) containing a crosslinked resin and a domain (island phase) containing an elastomer having a polyisobutylene backbone dispersed in the matrix, and the matrix is crosslinked. The crosslinking of the matrix contributes to heat resistance. As long as it is a co-continuous structure, the flexibility is excellent.

[0088] The reinforcing layer is not limited, and for example, it is a layer of woven fibers.

[0089] The reinforcing layer is not limited, and preferably contains polyester fiber, polyamide fiber, aramid fiber, PBO fiber, vinylon fiber or rayon fiber.

[0090] The inner layer is not limited, and is preferably formed of a thermoplastic resin composition having a sea-island structure in which an elastomer exists in the form of domains in a matrix containing a thermoplastic resin. Based on the mass of the thermoplastic resin, the thermoplastic resin contains 50% by mass or more and 100% by mass or less of polyamide, the elastomer contains an elastomer having a polyisobutylene backbone, and the content of the elastomer is 30% by mass or more and 80% by mass or less based on the mass of the thermoplastic resin composition. The thermoplastic resin composition also contains a phenylenediamine-based or quinoline-based anti-aging agent and a processing aid.

[0091] The thermoplastic resin constituting the matrix of the thermoplastic resin composition is not limited. Preferably, 50% by mass or more and 100% by mass or less of polyamide is contained based on the mass of the thermoplastic resin. More preferably, 75% by mass or more and 100% by mass or less of polyamide is contained based on the mass of the thermoplastic resin. Even more preferably, 95% by mass or more and 100% by mass or less of polyamide is contained based on the mass of the thermoplastic resin. By containing polyamide within the above numerical range, gas barrier properties can be ensured.

[0092] 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, nylon MXD6, etc. Among them, nylon 6 and nylon 6 / 12 copolymer are preferred.

[0093] The thermoplastic resin constituting the matrix of the thermoplastic resin composition may contain resins other than polyamide. Examples of the resins other than polyamide are not limited, and include polyester, polyvinyl alcohol, polyketone, etc.

[0094] The elastomer constituting the domain of the thermoplastic resin composition contains an elastomer having a polyisobutylene backbone. The elastomer having a polyisobutylene backbone is as described above.

[0095] The content of the elastomer is preferably 30% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 80% by mass or less, and even more preferably 50% by mass or more and 80% by mass or less based on the mass of the thermoplastic resin composition. By the content of the elastomer being within the above numerical range, it is ensured that the elastomer becomes a dispersed form of a sea-island structure of the domain, and flexibility and gas barrier properties can be ensured.

[0096] The thermoplastic resin composition constituting the inner layer preferably contains a phenylenediamine-based or quinoline-based anti-aging agent. By the thermoplastic resin composition containing a phenylenediamine-based or quinoline-based anti-aging agent, heat aging resistance is improved.

[0097] The phenylenediamine-based anti-aging agent refers to an anti-aging agent having an aromatic ring with 2 secondary amino groups as substituents in its molecular structure, 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. More preferably, it is N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine.

[0098] The quinoline-based anti-aging agent refers to an anti-aging agent having a quinoline backbone in its molecular structure, and is preferably 2,2,4-trimethyl-1,2-dihydroquinoline polymer.

[0099] The content of the phenylenediamine-based antioxidant or quinoline-based antioxidant is preferably 0.1 to 10% by mass, more preferably 0.1 to 5.0% by mass, based on the mass of the thermoplastic resin composition.

[0100] The thermoplastic resin composition constituting the inner layer preferably contains a processing aid. The processing aid helps to improve the extrusion processability of the thermoplastic resin composition.

[0101] There is no particular limitation on the processing aid, and at least one selected from fatty acids, fatty acid metal salts, fatty acid esters, and fatty acid amides is preferred.

[0102] Examples of the fatty acid include stearic acid, palmitic acid, lauric acid, oleic acid, linoleic acid, etc., and stearic acid is preferred.

[0103] Examples of the fatty acid metal salt include calcium stearate, potassium stearate, zinc stearate, magnesium stearate, sodium stearate, etc., and calcium stearate is preferred.

[0104] Examples of the fatty acid ester include glycerol monostearate, sorbitan stearate, stearyl stearate, ethylene glycol distearate, etc.

[0105] Examples of the fatty acid amide include stearic monoamide, oleic monoamide, ethylene bisstearamide, etc.

[0106] The content of the processing aid is preferably 0.2 to 10% by mass, more preferably 1 to 8% by mass, and further preferably 1 to 5% by mass, based on the mass of the thermoplastic resin composition.

[0107] The thermoplastic resin composition constituting the inner layer preferably contains a viscosity stabilizer. By containing the viscosity stabilizer, the increase in viscosity can be suppressed during the extrusion molding of the thermoplastic resin composition, and the occurrence of residues can be effectively reduced, so the processability is improved.

[0108] Examples of the viscosity stabilizer include divalent metal oxides, ammonium salts, carboxylates, etc.

[0109] Examples of the divalent metal oxide include zinc oxide, magnesium oxide, copper oxide, calcium oxide, iron oxide, etc., zinc oxide or magnesium oxide is preferred, and zinc oxide is more preferred.

[0110] Examples of the ammonium salt include ammonium carbonate, ammonium bicarbonate, ammonium chloride, ammonium bromide, ammonium sulfate, ammonium nitrate, ammonium acetate, alkylammonium, etc.

[0111] Examples of the carboxylate include sodium acetate, potassium acetate, zinc acetate, copper acetate, sodium oxalate, ammonium oxalate, calcium oxalate, iron oxalate, etc.

[0112] The viscosity stabilizer is most preferably zinc oxide.

[0113] The content of the viscosity stabilizer is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and still more preferably 0.5 to 5% by mass based on the mass of the thermoplastic resin composition.

[0114] Preferably, the matrix contains 50% by mass or more of the viscosity stabilizer. By containing 50% by mass or more of the viscosity stabilizer in the matrix, it is possible to suppress the increase in viscosity during the extrusion molding of the thermoplastic resin composition, and effectively reduce the occurrence of residues, so the processability is improved.

[0115] The thermoplastic resin composition constituting the inner layer may contain various additives in addition to the above-mentioned components.

[0116] There is no particular limitation on the manufacturing method of the refrigerant delivery hose, and it can be manufactured according to the following operations. First, the inner layer is extruded into a tubular shape by extrusion molding, then fibers for the reinforcing layer are woven on the tube, and further, the outer layer can be coated on the fibers by extrusion molding.

[0117] The method for manufacturing the refrigerant delivery hose of the present invention preferably includes the following steps: a step of melt-kneading an elastomer having a polyisobutylene backbone and a crosslinkable resin to prepare an outer layer composition; and a step of adding a silanol condensation catalyst to the outer layer composition during the extrusion molding of the hose, and extruding the composition added with the silanol condensation catalyst to form the outer layer.

[0118] Hereinafter, the step of melt-kneading an elastomer having a polyisobutylene backbone and a crosslinkable resin to prepare an outer layer composition is simply referred to as the "melt-kneading step".

[0119] There is no limitation on the melt-kneading, and a kneader, a single-screw or twin-screw kneading extruder, etc. can be used.

[0120] The temperature of the melt-kneading is not limited as long as it can perform melt-kneading, and is preferably 170 to 240 °C.

[0121] The time of the melt-kneading is not limited as long as it can prepare the target kneaded product, and is preferably 2 to 10 minutes.

[0122] In the melt-kneading step, an elastomer having a polyisobutylene backbone, a silane-modified resin, and various additives such as an anti-aging agent, a processing aid, and a viscosity stabilizer added as needed are put into a kneader, etc. for melt-kneading.

[0123] Among them, it is preferable not to add a silanol condensation catalyst in the melt-kneading step. When a silanol condensation catalyst is added in the melt-kneading step, if 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 slowly crosslinks, and the crosslinked outer layer composition becomes difficult to mold. Therefore, the silanol condensation catalyst is preferably added to the outer layer composition during molding.

[0124] Hereinafter, the step of adding a silanol condensation catalyst to the outer layer composition during the hose extrusion molding and extruding the composition added with the silanol condensation catalyst to form the outer layer is simply referred to as the "outer layer forming step".

[0125] The so-called "during extrusion molding" means simultaneously with the extrusion molding or within 6 hours before the extrusion molding.

[0126] There is no limitation on the extrusion molding, and a kneading extruder can be used. Preferably, a twin-screw kneading extruder is used.

[0127] The addition of the silanol condensation catalyst can be added to the outer layer composition before feeding it into the kneading extruder, or the outer layer composition and the silanol condensation catalyst can be fed into the kneading extruder simultaneously, or the outer layer composition and the silanol condensation catalyst can be fed into separate inlets of the kneading extruder respectively.

[0128] Regarding the silanol condensation catalyst, it can be directly added to the outer layer composition itself, but it is preferably added in the form of a masterbatch containing a resin and a silanol condensation catalyst.

[0129] The composition added with the silanol condensation catalyst is extruded onto the outer surface of the reinforcing layer to form the outer layer.

[0130] The conditions for the extrusion molding are not limited as long as the outer layer can be formed.

[0131] The method for manufacturing the refrigerant transfer hose of the present invention preferably includes a step of bringing the outer layer into contact with water or water vapor (hereinafter simply referred to as the "water contact step") after the outer layer forming step. By implementing the water contact step, the crosslinkable resin in the outer layer crosslinks, and the heat resistance of the outer layer is improved.

[0132] If 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 slowly crosslinks and a crosslinked resin is generated, and the outer layer crosslinks. However, when it is desired to rapidly crosslink the outer layer, it is preferable to implement the water contact step.

[0133] The method of bringing it into contact with water or water vapor is not limited, and examples include immersing it in a water bath, spraying water, placing it in an atmosphere containing water vapor, etc. The method of placing it in an atmosphere containing water vapor is preferred. In the method of placing it in an atmosphere containing water vapor, it is left standing in air at a temperature of room temperature to 200°C, preferably room temperature to 100°C, and a relative humidity of 30 to 100%, preferably 40 to 90%, for 1 minute to 1 month, preferably 1 hour to 1 week, more preferably 1 to 4 days. More specifically, it is preferably left standing in air at a temperature of 25°C and a relative humidity of 50% for 72 hours or more.

[0134] When the crosslinkable resin is a silane-modified resin, the hydrolyzable silyl group (preferably alkoxysilyl group) in the outer layer of the crosslinkable resin undergoes hydrolysis through the water contact step to generate silanol groups, and condensation reactions occur between the silanol groups to form siloxane bonds (Si-O-Si) for crosslinking, thereby obtaining a crosslinked outer layer.

[0135] Examples

[0136] [Raw materials]

[0137] The raw materials used in the following examples and comparative examples are as follows.

[0138] Nylon 6: Nylon 6 "UBE Nylon" (registered trademark) 1011FB manufactured by Ube Industries, Ltd.

[0139] Nylon 6 / 12: Nylon 6 / 12 copolymer "UBE Nylon" (registered trademark) 7024B manufactured by Ube Industries, Ltd.

[0140] Polypropylene: Propylene homopolymer "Prime Polypro" (registered trademark) J108M manufactured by Prime Polymer Co., Ltd.

[0141] Crosslinkable polypropylene: Silane-modified polypropylene "Linkron" (registered trademark) XPM800HM manufactured by Mitsubishi Chemical Corporation

[0142] IIR: Butyl rubber "Exxon Butyl" 268 manufactured by ExxonMobil Chemical Company

[0143] Br-IIR: Bromobutyl rubber "Exxon Bromobutyl" 2255 manufactured by ExxonMobil Chemical Company

[0144] Butyl rubber: Bromoisobutene-p-methylstyrene copolymer rubber "EXXPRO" (registered trademark) 3745 manufactured by ExxonMobil Chemical Company

[0145] PP / EPDM: ExxonMobil Japan Co., Ltd. - made PP / EPDM thermoplastic elastomer "Santoprene" (registered trademark) 111-35

[0146] Elastomer crosslinking agent - 1: Hitachi Chemical Co., Ltd. - made alkylphenol - formaldehyde resin "Hitanol" (registered trademark) 2501Y

[0147] Elastomer crosslinking agent - 2: Three types of zinc oxide made by Shoei Chemical Industry Co., Ltd.

[0148] Silanol condensation catalyst: Mitsubishi Chemical Corporation - made silane crosslinking agent masterbatch "Catalyst MB" PZ010

[0149] Antioxidant - 1: BASF Japan Ltd. - made hindered phenol - based antioxidant "IRGANOX" (registered trademark) 1010

[0150] Antioxidant - 2: Solutia - made phenylenediamine - based antioxidant "Santoflex" (registered trademark) 6PPD (substance name: N - phenyl - N′-(1,3 - dimethylbutyl) - p - phenylenediamine)

[0151] Viscosity stabilizer: Three types of zinc oxide made by Shoei Chemical Industry Co., Ltd.

[0152] Processing aid - 1: Industrial stearic acid made by Chiba Fatty Acids Co., Ltd.

[0153] Processing aid - 2: Calcium stearate SC - PG made by Sakai Chemical Industry Co., Ltd.

[0154] [Preparation of the outer layer resin composition]

[0155] The outer layer resin compositions A1, A2, A3, and A4 are prepared by the following method. Each raw material other than the silanol condensation catalyst is put into a twin - screw kneading and extruding machine (made by Japan Steel Works, Ltd.) at the formulation ratios shown in Table 1, and kneaded at 235°C for 3 minutes. By continuously extruding the kneaded material from the extruder into a strand - like shape, water - cooling it, and then cutting it with a cutter, the granular outer layer resin compositions A1, A2, A3, and A4 are obtained. The silanol condensation catalyst is added when forming a sheet through the extruder during the measurement of water vapor permeability and breaking strength, and is added during the tubular extrusion of the outer layer resin composition when manufacturing a refrigerant - conveying hose.

[0156] As the outer layer resin composition A5, a commercially available PP / EPDM thermoplastic elastomer "Santoprene" (registered trademark) 111 - 35 (with a matrix of polypropylene and a domain of a thermoplastic elastomer as an ethylene - propylene - diene copolymer) is used.

[0157] For the outer layer resin compositions A1, A2, A3, A4, and A5, the water vapor transmission rate and the breaking strength at 25°C and 100°C were measured, and TB was calculated. 100 / TB 25 . The measurement results are shown in Table 1.

[0158] [Preparation of the inner layer thermoplastic resin composition]

[0159] Each raw material was put into a twin-screw kneading and extruding machine (manufactured by Japan Steel Works, Ltd.) at the blending ratio shown in Table 2 and kneaded at 235°C for 3 minutes. By continuously extruding the kneaded material from the extruder into a strand-like shape, after water cooling, it was cut with a cutting machine to obtain granular inner layer thermoplastic resin compositions B1, B2, and B3.

[0160] [Manufacture of the refrigerant delivery hose]

[0161] The inner layer thermoplastic resin composition was extruded into a tube of the thickness shown in Table 3 on a mandrel pre-coated with a mold release agent by an extruder. By using a braiding machine to braid the reinforcing filaments of polyester thereon, and then extruding the outer layer resin composition added with a silanol condensation catalyst into a tube of the thickness shown in Table 3 thereon, the mandrel was pulled out to manufacture a hose formed of an inner layer / reinforcing layer / outer layer.

[0162] For the manufactured hose, it was left standing in air at a temperature of 25°C and a relative humidity of 50% for 72 hours or more. After crosslinking the outer layer resin composition, the refrigerant permeability resistance, water permeability resistance, flexibility, and heat resistance were evaluated. The evaluation results are shown in Table 3.

[0163] The measurement and evaluation methods are as follows.

[0164] [Measurement of the water vapor transmission rate]

[0165] A sample of the outer layer resin composition added with a silanol condensation catalyst was used with a 40 mmφ single-screw extruder equipped with a 550 mm wide T-die (developed by Plastech Co., Ltd.), and the temperatures of the barrel and the die were set to the melting point of the polymer component with the highest melting point in the sample composition + 10°C, and 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 drawing speed of 3 m / min. The manufactured sheet was left standing in air at a temperature of 25°C and a relative humidity of 50% for 72 hours or more to produce a sheet with the resin composition crosslinked.

[0166] The obtained sheet was cut, and a water vapor transmission tester manufactured by GTR Tech Co., Ltd. was used for measurement at a temperature of 60°C and a relative humidity of 95%.

[0167] [Measurement of the breaking strength]

[0168] A sheet with an average thickness of 0.2 mm made during the measurement of water vapor permeability is left standing in air at a temperature of 25 °C and a relative humidity of 50% for 72 hours or more to produce a sheet in which the resin composition is crosslinked. The sheet in which the resin composition is crosslinked is punched into a JIS No. 3 dumbbell shape, and according to the measurement method specified in JIS K6251 "Vulcanized Rubber and Thermoplastic Rubber - Method for Obtaining Tensile Properties", a tensile test is carried out under the conditions of a temperature of 25 °C and a speed of 500 mm / min and a temperature of 100 °C and a speed of 500 mm / min, and the stress at break (breaking strength) is obtained from the resulting stress-strain curve.

[0169] The breaking strength at 25 °C is designated as TB 25 and the breaking strength at 100 °C is designated as TB 100 , and their ratio TB 100 / TB 25 is calculated. TB 100 / TB 25 is an index of heat resistance, and the closer TB 100 / TB 25 is to 1.0, the more excellent the heat resistance.

[0170] [Evaluation of Refrigerant Permeability Resistance]

[0171] Measurements are carried out in accordance with SAE J2064 AUG2015. In each test sample S with a length of 1.07 m, a refrigerant (HFO-1234yf) is enclosed at 70% ± 3% with respect to the internal volume of each test sample S of 1 cm 3 . The test sample S is placed in an 80 °C atmosphere for 25 days, and the mass reduction amount (refrigerant permeation amount) [kg / day] per day during the last specified period (5 days to 7 days) within the 25-day period is measured. The value obtained by dividing this reduction amount by the internal surface area of the test sample S is converted into a value per year, thereby calculating the refrigerant permeation coefficient [kg / (m 2 ·year)]. The smaller the value of the refrigerant permeation coefficient, the more excellent the refrigerant permeability resistance. If this value is 3 or less, it can be evaluated that there is sufficient refrigerant permeability resistance in practice. In Table 3, when this value is 3 or less, it is indicated by 〇, and when this value exceeds 3, it is indicated by ×.

[0172] [Evaluation of Water Permeability Resistance]

[0173] Using each test sample S that has been placed in an oven at 50°C for 5 hours, a desiccant equivalent to 80% of the internal volume of the test sample S is filled therein, and it is sealed. The test sample S is placed in an atmosphere at a temperature of 50°C and a relative humidity of 95%, and the increase in the mass of the desiccant after 360 hours starting from 120 hours is measured. The increase in mass at around 240 hours is divided by the internal surface area of the test sample S to calculate the water vapor transmission coefficient [mg / (240h·cm 2 )]. The smaller the value of the water vapor transmission coefficient, the more excellent the moisture resistance. If this value is 3 or less, it can be evaluated that it has sufficient moisture resistance for practical use. In Table 1, the case where this value is 3 or less is indicated by 〇, and the case where this value exceeds 3 is indicated by ×.

[0174] [Evaluation of flexibility]

[0175] As Figure 2 shown, for each test sample S, one end of the length direction is fixed using a fixing tool such as a clamp, and a spring scale is installed at the other end only at a distance of a specified length L (120 + outer diameter of the hose / 2) × π [mm] from the fixed position and pulled. The test sample S is bent from the state shown by the dotted line into a semi-circular arc shape to the state shown by the solid line. Moreover, the tensile force F measured by the spring scale pulled along the horizontal direction in the bent state where the inner radius R of the hose is 120 mm is used as an evaluation index. The smaller the value of this tensile force F, the easier it is for the test sample S to bend and the more excellent the flexibility. If this tensile force F is 20 N or less, it can be evaluated that it has sufficient flexibility for practical use. In Table 3, the case where this tensile force F is 20 N or less is indicated by 〇, and the case where this tensile force F exceeds 20 N is indicated by ×.

[0176] [Evaluation of heat resistance]

[0177] The test sample S that has been placed in an oven at 150°C for 168 h is pressurized to an internal pressure of 3.5 MPa, and the airtightness of the fastened part after heat aging is confirmed by maintaining an airtight test for 5 minutes. The case without leakage is recorded as 〇, and the case with leakage is recorded as ×.

[0178]

[0179] Table 2 Ingredients of the inner layer thermoplastic resin composition

[0180]

[0181]

[0182] Industrial applicability

[0183] The refrigerant transfer hose of the present invention can be suitably used for transferring refrigerants for air conditioners of automobiles and the like.

[0184] Explanation of Reference Numerals

[0185] 1 Refrigerant transfer hose 2 Inner layer

[0186] 3 Reinforcement layer

[0187] 4 Outer layer

[0188] F Tensile force

[0189] L Specified length

[0190] R Inner radius of the hose

[0191] S Test sample

Claims

1. A refrigerant delivery hose, which is a refrigerant delivery hose comprising an outer layer, a reinforcing layer, and an inner layer. Wherein, The outer layer is formed of a resin composition containing an elastomer having a polyisobutylene backbone and a crosslinked resin. The content of the elastomer having a polyisobutylene backbone in the resin composition is 30% by mass or more and 90% by mass or less based on the mass of the resin composition. The content of the crosslinked resin in the resin composition is 10% by mass or more and 70% by mass or less based on the mass of the resin composition. The water vapor transmission rate of the resin composition is 2.0 g·mm / (m 2 ·24 h) or less, and the breaking strength TB of the resin composition at 100 °C 100 and the breaking strength TB at 25 °C 25 The ratio TB 100 / TB 25 is 0.2 to 1.

0. The crosslinked resin is a resin obtained by modifying a thermoplastic resin with a silane compound and crosslinking the resulting silane-modified resin.

2. The refrigerant delivery hose according to claim 1, Wherein, The crosslinked resin is a resin obtained by modifying a polyolefin with a silane compound and crosslinking the resulting silane-modified polyolefin.

3. The refrigerant delivery hose according to claim 2, Wherein, The crosslinked resin is a resin obtained by modifying polypropylene with a silane compound and crosslinking the resulting silane-modified polypropylene.

4. The refrigerant delivery hose according to any one of claims 1 to 3, Wherein, The elastomer having a polyisobutylene backbone is butyl rubber or modified butyl rubber, and the elastomer having a polyisobutylene backbone is dynamically crosslinked.

5. The refrigerant delivery hose according to any one of claims 1 to 3, Wherein, The resin composition contains an anti-aging agent in an amount of 1% by mass or more and 4% by mass or less based on the mass of the resin composition.

6. The refrigerant delivery hose according to any one of claims 1 to 3, Wherein, The inner layer is formed of a thermoplastic resin composition having a sea-island structure in which an elastomer exists in a domain form in a matrix containing a thermoplastic resin, and the thermoplastic resin contains 50% by mass or more and 100% by mass or less of polyamide based on the mass of the thermoplastic resin. The elastomer contains an elastomer having a polyisobutylene backbone, and the content of the elastomer is 30% by mass or more and 80% by mass or less based on the mass of the thermoplastic resin composition. The thermoplastic resin composition further contains a phenylenediamine-based or quinoline-based anti-aging agent and a processing aid.

7. The refrigerant delivery hose according to any one of claims 1 to 3, Wherein, The reinforcing layer contains polyester fiber, polyamide fiber, aromatic polyamide fiber, PBO fiber, vinylon fiber, or rayon fiber.

8. A method for manufacturing a refrigerant delivery hose, which is a method for manufacturing the refrigerant delivery hose according to any one of claims 1 to 7, Wherein, The method includes the following steps: A step of melt-kneading an elastomer having a polyisobutylene backbone and a crosslinkable resin to prepare a composition for the outer layer, and A step of adding a silanol condensation catalyst to the composition for the outer layer during the extrusion molding of the hose, and extruding the composition added with the silanol condensation catalyst to form the outer layer. The crosslinkable resin is a silane-modified resin obtained by modifying a thermoplastic resin with a silane compound.

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