WO2024252757A1 - Thermoplastic resin composition for refrigerant transport hose, and refrigerant transport hose - Google Patents

Abstract

The present invention provides a refrigerant transport hose that exhibits good flexibility, good resistance to refrigerant permeation, and good resistance to deterioration. The thermoplastic resin composition for a refrigerant transport hose has a sea-island structure in which an elastomer is present in domain form in a matrix including a thermoplastic resin, said thermoplastic resin composition characterized by comprising 100 parts by mass of an elastomer, 30-100 parts by mass of a thermoplastic resin, and 0.5-10 parts by mass of a hydrotalcite and/or a magnesium-aluminum solid solution, wherein the thermoplastic resin includes 50-100 parts by mass of a polyamide on the basis of 100 parts by mass of the thermoplastic resin, and the elastomer includes an elastomer having a polyisobutylene skeleton.

Description

Thermoplastic resin composition for refrigerant transport hose and refrigerant transport hose

The present invention relates to a thermoplastic resin composition for a refrigerant transport hose and a refrigerant transport hose. More specifically, the present invention relates to a thermoplastic resin composition used to manufacture a refrigerant transport hose for use in an automobile air conditioner or the like, and a refrigerant transport hose including a layer made of the thermoplastic resin composition.

Amid increasing demand for lighter vehicles, there are efforts to achieve weight reduction by replacing the rubber hoses currently used in cars with rubber and making them thinner using resins with high barrier properties. In particular, the main material of the refrigerant transport hoses in current car air conditioners is rubber, and if this main material could be replaced with resins with high barrier properties, weight reduction would be possible.

　JP 2011-58638 A (Patent Document 1) describes a refrigerant transport hose having an innermost layer obtained using a polyamide resin composition to which an acid acceptor such as hydrotalcite has been added.

JP 2011-58638 A

The refrigerant transport hose described in Patent Document 1 has high resistance to deterioration because the hydrolysis of polyamide can be suppressed by adding an acid acceptor, but flexibility and resistance to refrigerant permeation are not necessarily sufficient.

The present invention provides a thermoplastic resin composition and a refrigerant transport hose that are used to manufacture a refrigerant transport hose that has good flexibility, refrigerant permeability resistance, and deterioration resistance.

The present invention (I) is a thermoplastic resin composition for a refrigerant transport hose, which has a sea-island structure in which an elastomer exists as domains in a matrix containing a thermoplastic resin, characterized in that the thermoplastic resin composition contains 100 parts by mass of an elastomer, 30 to 100 parts by mass of a thermoplastic resin, and 0.5 to 10 parts by mass of a hydrotalcite and/or a magnesium-aluminum solid solution, the thermoplastic resin contains 50 to 100 parts by mass of a polyamide based on 100 parts by mass of the thermoplastic resin, and the elastomer contains an elastomer having a polyisobutylene skeleton.
The present invention (II) is a refrigerant transport hose comprising a layer made of the thermoplastic resin composition for a refrigerant transport hose of the present invention (I).

The present invention includes the following embodiments.
[1] A thermoplastic resin composition for a refrigerant transport hose, having an island-sea structure in which an elastomer exists as domains in a matrix containing a thermoplastic resin, the thermoplastic resin composition comprising 100 parts by mass of an elastomer, 30 to 100 parts by mass of a thermoplastic resin, and 0.5 to 10 parts by mass of a hydrotalcite and/or a magnesium-aluminum solid solution, the thermoplastic resin comprising 50 to 100 parts by mass of a polyamide based on 100 parts by mass of the thermoplastic resin, and the elastomer comprising an elastomer having a polyisobutylene skeleton.
[2] The thermoplastic resin composition for a refrigerant transport hose according to [1], wherein the thermoplastic resin composition contains at least one selected from the group consisting of zinc oxide, a phenylenediamine-based or quinoline-based antioxidant, and a processing aid.
[3] The thermoplastic resin composition for a refrigerant transport hose according to [1], wherein the polyamide is at least one selected from the group consisting of polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 6/66 copolymer, polyamide 6/12 copolymer, polyamide 46, polyamide 6T, polyamide 9T and polyamide MXD6.
[4] The thermoplastic resin composition for a refrigerant transport hose according to [1], wherein the elastomer having a polyisobutylene skeleton is at least one selected from the group consisting of butyl rubber, halogenated butyl rubber, isobutylene-monoalkylstyrene copolymer rubber, halogenated isobutylene-monoalkylstyrene copolymer rubber, and styrene-isobutylene-styrene block copolymer.
[5] The thermoplastic resin composition for a refrigerant transport hose according to [1], wherein the hydrotalcites and/or magnesium-aluminum solid solution have a specific surface area of 100 m ² /g or more.
[6] The thermoplastic resin composition for a refrigerant transport hose according to [1], further comprising a first fatty acid metal salt and a second fatty acid metal salt having a melting point lower than that of the first fatty acid metal salt.
[7] The thermoplastic resin composition for a refrigerant transport hose according to [6], wherein the melting point of the first fatty acid metal salt is 150°C or higher.
[8] The thermoplastic resin composition for a refrigerant transport hose according to [7], wherein the melting point of the second fatty acid metal salt is less than 150°C.
[9] The thermoplastic resin composition for a refrigerant transport hose according to [6], wherein the first fatty acid metal salt is 0.5 to 5.0 parts by mass based on 100 parts by mass of the elastomer.
[10] The thermoplastic resin composition for a refrigerant transport hose according to [6], wherein the second fatty acid metal salt is 0.5 to 5.0 parts by mass based on 100 parts by mass of the elastomer.
[11] The thermoplastic resin composition for a refrigerant transport hose according to [6], wherein the ratio Wd1/Wd2 of the mass Wd1 of the first fatty acid metal salt to the mass Wd2 of the second fatty acid metal salt is 0.5 to 5.0.
[12] The thermoplastic resin composition for a refrigerant transport hose according to [6], wherein the first fatty acid metal salt is at least one selected from the group consisting of calcium stearate, zinc 12-hydroxystearate, and lithium 12-hydroxystearate.
[13] The thermoplastic resin composition for a refrigerant transport hose according to [6], wherein the second fatty acid metal salt is at least one selected from the group consisting of zinc stearate and magnesium stearate.
[14] A refrigerant transport hose comprising a layer made of the thermoplastic resin composition according to [1].
[15] The refrigerant transport hose according to [14], which comprises an inner layer, a reinforcing layer and an outer layer, and the inner layer is a layer made of the thermoplastic resin composition according to [1].
[16] The refrigerant transport hose according to [14], which does not contain a layer made of vulcanized rubber.

The thermoplastic resin composition for a refrigerant transport hose of the present invention is excellent in flexibility, refrigerant permeation resistance and deterioration resistance.
The refrigerant transport hose of the present invention is excellent in flexibility, refrigerant permeation resistance and deterioration resistance.

FIG. 1 is a cross-sectional view of a refrigerant transport hose. FIG. 2 is a diagram showing a method for evaluating the flexibility of a hose.

The present invention (I) relates to a thermoplastic resin composition for a refrigerant transport hose. The thermoplastic resin composition of the present invention is used to manufacture a refrigerant transport hose. The thermoplastic resin composition of the present invention is preferably used as a material constituting the inner layer of the refrigerant transport hose.

The thermoplastic resin composition of the present invention has an island-in-sea structure in which an elastomer exists as domains in a matrix containing a thermoplastic resin. The island-in-sea structure allows the thermoplastic resin composition to have flexibility. To obtain the island-in-sea structure, the rubber is crosslinked (dynamic crosslinking) during kneading.

The thermoplastic resin composition of the present invention contains 100 parts by mass of elastomer, 30 to 100 parts by mass of thermoplastic resin, and 0.5 to 10 parts by mass of hydrotalcites and/or magnesium-aluminum solid solution.

An elastomer is a polymeric substance that exhibits rubber elasticity at room temperature.
The elastomer includes an elastomer having a polyisobutylene backbone.
The polyisobutylene skeleton refers to a chemical structure formed by polymerization of a plurality of isobutylene units, that is, a chemical structure represented by --[--CH ₂ --C(CH ₃ ) ₂ --] _n -- (where n is an integer of 2 or more).
The elastomer having a polyisobutylene skeleton is not limited as long as it has a polyisobutylene skeleton, but is preferably at least one selected from the group consisting of butyl rubber (IIR), halogenated butyl rubber, isobutylene-monoalkylstyrene copolymer rubber, halogenated isobutylene-monoalkylstyrene copolymer rubber, and styrene-isobutylene-styrene block copolymer (SIBS). An example of the isobutylene-monoalkylstyrene copolymer rubber is isobutylene-p-methylstyrene copolymer rubber (IPMS). An example of the halogenated isobutylene-monoalkylstyrene copolymer rubber is halogenated isobutylene-p-methylstyrene copolymer rubber. The elastomer is more preferably brominated isobutylene-p-methylstyrene copolymer rubber (BIMS).
The elastomer may contain an elastomer other than the elastomer having a polyisobutylene skeleton, as long as the effects of the present invention are not impaired.

The thermoplastic resin contains 50 to 100 parts by mass of polyamide, preferably 70 to 100 parts by mass of polyamide, and more preferably 80 to 100 parts by mass of polyamide, based on 100 parts by mass of the thermoplastic resin. By containing polyamide in the thermoplastic resin, gas barrier properties can be ensured.
The polyamide is preferably, but not limited to, at least one selected from the group consisting of polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 6/66 copolymer, polyamide 6/12 copolymer, polyamide 46, polyamide 6T, polyamide 9T, and polyamide MXD6.
The thermoplastic resin may include thermoplastic resins other than polyamide, including, but not limited to, polyester, polyvinyl alcohol, polyketone, and the like.
The thermoplastic resin may include thermoplastic resins other than polyamide, but preferably includes only polyamide.

The content of the thermoplastic resin in the thermoplastic resin composition is 30 to 100 parts by mass, preferably 31 to 95 parts by mass, and more preferably 31 to 80 parts by mass, based on 100 parts by mass of the elastomer. When the content of the thermoplastic resin is within the above numerical range, it is possible to achieve both flexibility and resistance to refrigerant permeation.

The thermoplastic resin composition of the present invention contains hydrotalcites and/or a magnesium-aluminum solid solution.
When a thermoplastic resin composition containing polyamide is used for the inner layer of a refrigerant transport hose, acid generated due to deterioration of a lubricant such as an ester-based oil in the refrigerant promotes hydrolysis of the polyamide in the inner layer and reduces the deterioration resistance of the inner layer. However, by containing hydrotalcites and/or magnesium-aluminum solid solution, the hydrotalcites and/or magnesium-aluminum solid solution can capture the acid and suppress the decrease in the deterioration resistance of the inner layer.
Hydrotalcites are non-stoichiometric compounds represented by the general formula: [M2 ⁺ _1- ^xM3+ _x (OH) ₂ ] ^x+ [An ^- _{x/ n.mH2O} ] ^x- . ^M2+ is a divalent metal such as Mg2 ⁺ , Mn2 ⁺ , Fe2 ⁺ , Co2 ⁺ , Ni2 ⁺ , Cu2 ⁺ , or Zn2 ⁺ . M3 ⁺ is a trivalent metal such as Al3 ⁺ , Fe3 ⁺ , Cr3 ⁺ , Co3 ⁺ , or In3 ⁺ . A ^n- is an n-valent anion such as OH ^- , F ^- , Cl ^- , Br ^- , NO ₃ ^- , CO ₃ ^2- , SO ₄ ^2- , Fe(CN) ₆ ^3- , CH ₃ COO ^- , oxalate ion, salicylate ion, etc. x is in the range of 0<x≦0.33.
A representative mineral of hydrotalcites is a mineral having a chemical composition of Mg _1-x Al _x (OH) ₂ (CO ₃ ) _{x /2.nH 2} O. The chemical composition of hydrotalcite is (Mg ₆ Al ₂ (OH) ₂ (CO ₃ ) _{16.4H 2} O).
Hydrotalcites include natural and synthetic products, and either type of hydrotalcite can be used in the present invention.
Hydrotalcites are commercially available and can be obtained, for example, from Setras Holdings Co., Ltd. under the trade names DHT (registered trademark)-4C, DHT (registered trademark)-4A, and the like.
The magnesium aluminum solid solution is a magnesium aluminum oxide and has a dehydrating effect. The magnesium aluminum solid solution preferably has an MgO content of 55 to 65% and an Al ₂ O ₃ content of 30 to 40%. When the chemical composition of the magnesium aluminum solid solution is expressed as Mg _a Al _b O _c , it is preferable that a = 0.7, b = 0.3, and c = 1.15. The magnesium aluminum solid solution is commercially available, and can be obtained, for example, from Setras Holdings Co., Ltd. under the trade names KW-2000, KW-2100, KW-2200, etc.
The hydrotalcites and/or magnesium aluminum solid solution preferably have a specific surface area of 100 ^m2 /g or more, and more preferably 100 to 200 ^m2 /g. When the specific surface area of the hydrotalcites and/or magnesium aluminum solid solution is within the above range, the deterioration resistance of the thermoplastic resin composition is improved.
The hydrotalcites and/or magnesium-aluminum solid solutions may be contained in either the matrix or the domains, but are preferably contained in the matrix.

The content of hydrotalcites and/or magnesium-aluminum solid solution in the thermoplastic resin composition is 0.5 to 10 parts by mass, preferably 0.5 to 8 parts by mass, and more preferably 0.5 to 6 parts by mass, based on 100 parts by mass of elastomer. If the content of hydrotalcites and/or magnesium-aluminum solid solution is too low, the deterioration resistance of the thermoplastic resin composition becomes insufficient. If the content of hydrotalcites and/or magnesium-aluminum solid solution is too high, fatigue resistance and durability become poor.
The thermoplastic resin composition may contain either or both of hydrotalcites and magnesium-aluminum solid solution. When the thermoplastic resin composition contains both, the total content of the hydrotalcites and the magnesium-aluminum solid solution is 0.5 to 10 parts by mass based on 100 parts by mass of the elastomer.

The thermoplastic resin composition of the present invention preferably contains at least one selected from the group consisting of zinc oxide, phenylenediamine or quinoline antioxidants, and processing aids. By containing at least one selected from the group consisting of zinc oxide, phenylenediamine or quinoline antioxidants, and processing aids, the extrusion processability of the thermoplastic resin composition is improved. The three additives of zinc oxide, phenylenediamine or quinoline antioxidants, and processing aids may contain only one of them, any two of them, or all three of them.

Zinc oxide is also known as zinc white.
Zinc oxide functions as a viscosity stabilizer, and by including zinc oxide in the thermoplastic resin composition, an increase in viscosity during extrusion molding of the thermoplastic resin composition can be suppressed, and the occurrence of retained matter can be effectively reduced, resulting in good processability.
Zinc oxide is commercially available, for example, from Seido Chemical Industry Co., Ltd. under the trade name Zinc Oxide Type 3.
The content of zinc oxide is not limited as long as the desired effect is obtained, but 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 6 parts by mass, based on 100 parts by mass of the total amount of the thermoplastic resin and the elastomer.
Zinc white may be contained in either the matrix or the domain, but it is preferable that 50% by mass or more of zinc white is contained in the matrix. By containing 50% by mass or more of zinc white in the matrix, an increase in viscosity during extrusion molding of the thermoplastic resin composition can be suppressed and the occurrence of retained matter can be effectively reduced, resulting in good processability.

The phenylenediamine-based or quinoline-based antioxidant functions as an antioxidant and/or a crosslinking agent, improves the heat aging resistance of the thermoplastic resin composition, and contributes to improving the extrusion processability.
The phenylenediamine-based antioxidant refers to an antioxidant having in its molecular structure an aromatic ring having two secondary amines as substituents, and is preferably at least one selected from the group consisting 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 N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine.
Phenylenediamine-based antioxidants are commercially available, for example, from Solutia under the trade name 6PPD.
The quinoline-based 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.
Quinoline-based antioxidants are commercially available and can be obtained, for example, from Ouchi Shinko Chemical Industry Co., Ltd. under the trade name "Nocrac" (registered trademark) 224.
The content of the phenylenediamine-based antioxidant or quinoline-based antioxidant in the thermoplastic resin composition (in the case where both a phenylenediamine-based antioxidant and a quinoline-based antioxidant are contained, the total content of the phenylenediamine-based antioxidant and the quinoline-based antioxidant) is not limited as long as the desired effects can be obtained, but 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.
The phenylenediamine or quinoline antioxidant may be contained in either the matrix or the domain, but is preferably contained in the domain.

The processing aid contributes to improving the extrusion processability of the thermoplastic resin composition.
The processing aid is not particularly limited, but is preferably at least one selected from fatty acids, fatty acid metal salts, fatty acid esters, and fatty acid amides.
Examples of fatty acids include stearic acid, palmitic acid, lauric acid, oleic acid, and linoleic acid, with stearic acid being preferred.
Examples of fatty acid metal salts include calcium stearate, aluminum stearate, zinc 12-hydroxystearate, lithium 12-hydroxystearate, potassium stearate, zinc stearate, magnesium stearate, and sodium stearate.
Examples of fatty acid esters include glycerin monostearate, sorbitan stearate, stearyl stearate, and ethylene glycol distearate.
Examples of the fatty acid amide include stearic acid monoamide, oleic acid monoamide, and ethylene bisstearic acid amide.
The content of the processing aid in the thermoplastic resin composition is not limited as long as the desired effect is obtained, but 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.
The processing aid may be contained in either the matrix or the domain, but is preferably contained in the matrix.

In the present invention, the thermoplastic resin composition preferably contains both a first fatty acid metal salt and a second fatty acid metal salt having a melting point lower than that of the first fatty acid metal salt.
By adding the first fatty acid metal salt having a high melting point as a processing aid, the first fatty acid metal salt has good mobility at the temperature when the alloy of the thermoplastic resin and the elastomer is kneaded and extruded, and has a high effect as a processing aid, but the first fatty acid metal salt has insufficient molecular mobility at the operating temperature of the refrigerant transport hose (for example, 150°C or lower), and its effect as an acid acceptor is limited. Simply increasing the amount of fatty acid metal salt to enhance the acid-accepting effect improves flexibility, but there is a concern that the barrier property may be insufficient.
The second metal fatty acid salt having a low melting point has high molecular mobility at the operating temperature of the refrigerant transport hose (for example, 150° C. or lower), and can be highly effective as an acid acceptor.
In the present invention, by further adding a second fatty acid metal salt having a low melting point in addition to a first fatty acid metal salt having a high melting point, it is possible to improve hydrolysis resistance without impairing flexibility and barrier properties at the operating temperature of the refrigerant transport hose.

From the viewpoint of processability and deterioration resistance of the thermoplastic resin composition, the melting point of the first fatty acid metal salt is preferably 150°C or higher. From the same viewpoint, the melting point of the second fatty acid metal salt is preferably less than 150°C. The melting point of the first fatty acid metal salt may be 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, 190°C or higher, 200°C or higher, or 210°C or higher. On the other hand, the melting point of the second fatty acid metal salt may be less than 150°C, 145°C or lower, 140°C or lower, 135°C or lower, 130°C or lower, or 125°C or lower.

From the viewpoints of flexibility, barrier properties, and processability, the first fatty acid metal salt in the thermoplastic resin composition is preferably 0.5 to 5.0 parts by mass based on 100 parts by mass of elastomer. The first fatty acid metal salt in the thermoplastic resin composition is more preferably 1.0 to 3.0 parts by mass, and even more preferably 2.0 to 2.5 parts by mass based on 100 parts by mass of elastomer.

From the viewpoint of deterioration resistance, the second fatty acid metal salt in the thermoplastic resin composition is preferably 0.5 to 5.0 parts by mass based on 100 parts by mass of elastomer. The second fatty acid metal salt in the thermoplastic resin composition is more preferably 0.5 to 2.0 parts by mass, and even more preferably 0.5 to 1.0 part by mass based on 100 parts by mass of elastomer.

From the viewpoint of a balance between flexibility, barrier properties, processability, and resistance to deterioration, it is preferable that the ratio Wd1/Wd2 of the mass Wd1 of the first fatty acid metal salt to the mass Wd2 of the second fatty acid metal salt is 0.5 to 5.0.

The first fatty acid metal salt is preferably at least one selected from the group consisting of calcium stearate (melting point: 155±5° C.), zinc 12-hydroxystearate (melting point: 150±10° C.), and lithium 12-hydroxystearate (melting point: 212±10° C.).
The second fatty acid metal salt is preferably at least one selected from the group consisting of zinc stearate (melting point: 125±5° C.) and magnesium stearate (melting point: 145±5° C.).

The thermoplastic resin composition may contain additives other than those mentioned above, provided that they do not impair the effects of the present invention.

The thermoplastic resin composition of the present invention preferably has a breaking elongation (post-treatment EB) in a tensile test after treating the thermoplastic resin composition in a refrigerant-containing composition containing a refrigerant, refrigerating machine oil, and water for 96 hours at 150°C, which is 30 to 100% of the breaking elongation (pre-treatment EB) in a tensile test of the thermoplastic resin composition before treatment. Post-treatment EB/pre-treatment EB x 100 [%] is hereinafter referred to as the "post-treatment EB residual rate." The post-treatment EB residual rate is more preferably 35 to 100%, and even more preferably 50 to 100%. If a refrigerant transport hose is produced using a thermoplastic resin composition having a post-treatment EB residual rate within the above numerical range, a refrigerant transport hose with excellent resistance to deterioration can be obtained.

The measurement of the elongation at break (EB) is carried out as follows.
The thermoplastic resin composition is molded into a sheet having an average thickness of 1.0 mm using a 40 mmφ single-screw extruder equipped with a 200 mm wide T-type die (manufactured by Plagiken Co., Ltd.) with the cylinder and die temperatures set to the melting point of the polymer component with the highest melting point in the thermoplastic resin composition + 10°C, at a cooling roll temperature of 50°C and a take-up speed of 3 m/min. The molded sheet is punched out into a JIS No. 6 dumbbell shape to prepare test pieces of the thermoplastic resin composition.
A tensile test is performed on the prepared test piece of the thermoplastic resin composition in accordance with JIS K7161 at a temperature of 25°C, a relative humidity of 50%, and a speed of 500 mm/min. The elongation at break is determined from the obtained stress-strain curve, and this elongation is defined as the break elongation (EB).

The method for measuring EB after treatment is as follows.
A JIS No. 6 dumbbell-shaped test piece of the thermoplastic resin composition prepared for measuring the breaking elongation is sealed in a constant volume container together with water, refrigerating machine oil, and a refrigerant, and is subjected to a heat treatment at a predetermined temperature for a predetermined time. The amounts of the water, refrigerating machine oil, and refrigerant charged are in a mass ratio of 1:80:160.
After the treatment, a test piece of the thermoplastic resin composition is taken out of the constant volume container, and the breaking elongation of the test piece is measured, which is defined as the post-treatment EB.
The EB remaining rate after treatment is measured as follows.
The breaking elongation of a test piece of an untreated thermoplastic resin composition is measured, and this is defined as pre-treatment EB.
The EB remaining rate after treatment is calculated by the following formula.
EB remaining rate after processing (%)=EB after processing/EB before processing×100

The thermoplastic resin composition of the present invention preferably has a 10% modulus of 10 MPa or less, more preferably 2 to 10 MPa, and even more preferably 5 to 9 MPa at a temperature of 25° C. If a refrigerant transport hose is produced using a thermoplastic resin composition having a 10% modulus at a temperature of 25° C. within the above numerical range, a refrigerant transport hose with excellent flexibility can be obtained.
The 10% modulus is measured in accordance with JIS K7161.

The thermoplastic resin composition of the present invention has an oxygen permeability coefficient at a temperature of 21° C. and a relative humidity of 50% of preferably 0.03 ^cm3 ·mm/( ^m2 ·day·mmHg) or less, more preferably 0.0001 to 0.0300 ^cm3 ·mm/( ^m2 ·day·mmHg), and even more preferably 0.0050 to 0.0200 ^cm3 ·mm/( ^m2 ·day·mmHg). If a refrigerant transport hose is produced using a thermoplastic resin composition having an oxygen permeability coefficient at a temperature of 21° C. and a relative humidity of 50% within the above numerical range, a refrigerant transport hose having excellent refrigerant permeability resistance can be obtained.
The oxygen permeability coefficient refers to the amount of oxygen that permeates per day per 1 mmHg pressure, per 1 ^m2 area, and per 1 mm thickness under specified temperature and humidity conditions.

The present invention (II) relates to a hose for transporting a refrigerant.
The refrigerant transport hose refers to a hose for transporting refrigerant such as air conditioners. The refrigerant transport hose of the present invention (II) is particularly suitable for use as a hose for transporting refrigerant in automotive air conditioners. Examples of refrigerants for air conditioners include hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), hydrocarbons, carbon dioxide, ammonia, and water. 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.

Fig. 1 shows a cross-sectional view of one embodiment of a refrigerant transport hose of the present invention. However, the present invention is not limited to the one shown in Fig. 1.
The refrigerant transport hose 1 includes an inner layer 2, a reinforcing layer 3, and an outer layer 4. The reinforcing layer 3 is disposed on the outside of the inner layer 2, and the outer layer 4 is disposed on the outside of the reinforcing layer 3.

The refrigerant transport hose of the present invention (II) is characterized in that it comprises a layer made of the thermoplastic resin composition of the present invention (I). In Fig. 1, the layer made of the thermoplastic resin composition of the present invention (I) is an inner layer 2.
The inner layer 2 is preferably made of the thermoplastic resin composition of the present invention (I). When the inner layer 2 is made of the thermoplastic resin composition of the present invention (I), the refrigerant transport hose has improved refrigerant permeation resistance.

The thickness of the inner layer is not particularly limited, but may be, for example, 0.2 to 3 mm.

The reinforcing layer is a layer provided between the inner layer and the outer layer, and the reinforcing material that can form the reinforcing layer is not particularly limited, and may be either an organic material or an inorganic material. For example, the organic material may be a polymer (fiber material), such as polyester, polyamide, aramid, vinylon, rayon, PBO (polyparaphenylene benzobisoxazole), polyketone, polyarylate, etc. Examples of the inorganic material include metal, such as brass-plated wire and zinc-plated wire. The reinforcing material may be surface-treated. The reinforcing layer is preferably made of polyester-based fiber from the viewpoint of excellent fatigue resistance and excellent cost performance. By having the reinforcing layer, the strength of the hose can be ensured and the pressure resistance can be excellent. The thickness of the reinforcing layer is not particularly limited, but may be, for example, 0.3 to 3 mm.
The reinforcing layer (reinforcing material) may preferably be braided into a spiral structure and/or a braid structure, and may be a single reinforcing layer or a plurality of reinforcing layers.

Materials constituting the outer layer 4 include, but are not limited to, thermoplastic elastomers, vulcanized rubber, etc., and are preferably thermoplastic elastomers. Thermoplastic elastomers include, but are not limited to, polyolefin elastomers, polyester elastomers, polyamide elastomers, and polyurethane elastomers. More preferably, thermoplastic elastomers using polypropylene and thermoplastic elastomers using polyamide 12 are included.

The thickness of the outer layer is not particularly limited, but may be, for example, 0.2 to 3 mm.

The refrigerant transport hose preferably does not include a layer made of vulcanized rubber. By not including a layer made of vulcanized rubber, the number of hose manufacturing processes is reduced (specifically, the vulcanization process is omitted), resulting in energy savings.

The manufacturing method of the refrigerant transport hose is not particularly limited, but it can be manufactured as follows. First, the inner layer (inner tube) is extruded into a tube shape by extrusion molding, then a reinforcing material is braided on the tube to form a reinforcing layer, and the outer layer (outer tube) is further extruded onto the reinforcing layer to produce the refrigerant transport hose.

Examples 1 to 11 and Comparative Examples 1 to 3
[raw materials]
BIMS: Brominated isobutylene-p-methylstyrene copolymer rubber "EXXPRO" (registered trademark) 3745 manufactured by ExxonMobil Chemical Corporation
Acid-modified PO elastomer: Maleic acid-modified α-olefin copolymer "Tafmer" (registered trademark) MH7010 manufactured by Mitsui Chemicals, Inc.
PA6: Polyamide 6 "UBE Nylon" (registered trademark) 1011FB manufactured by Ube Industries, Ltd.
PA6/12: Polyamide 6/12 copolymer "UBE Nylon" (registered trademark) 7024B manufactured by Ube Industries, Ltd.
PA12: Polyamide 12 "UBESTA" (registered trademark) 3012U manufactured by Ube Industries, Ltd.
Magnesium-aluminum solid solution: Magnesium-aluminum solid solution KW-2200 (specific surface area: 145 m ² /g) manufactured by Setras Holdings Co., Ltd. (hereinafter, "magnesium-aluminum solid solution" is also referred to as "Mg.Al solid solution").
Hydrotalcites: Hydrotalcite "DHT" (registered trademark)-4C (specific surface area: 15 m ² /g) manufactured by Setras Holdings Co., Ltd.
Zinc oxide: Three types of zinc oxide manufactured by Seido Chemical Industry Co., Ltd. (zinc oxide mixed with polyamide 6 as a master batch with the zinc oxide content listed in the table)
6PPD: Solutia's phenylenediamine-based antioxidant "SANTOFLEX" (registered trademark) 6PPD (substance name: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine)
Calcium stearate: Calcium stearate SC-PG manufactured by Sakai Chemical Industry Co., Ltd.
Stearic acid: Industrial stearic acid manufactured by Chiba Fatty Acid Co., Ltd.

(1) Preparation of Thermoplastic Resin Compositions The raw materials were charged into a twin-screw kneading extruder (manufactured by The Japan Steel Works, Ltd.) in the blending ratios shown in Tables 1 and 2, and kneaded for 3 minutes at 235° C. The kneaded product was continuously extruded from the extruder in the form of a strand, cooled with water, and cut with a cutter to obtain pellet-shaped thermoplastic resin compositions A1 to A14.
The thermoplastic resin compositions A1 to A14 thus obtained were measured for the post-treatment EB residual rate, 10% modulus and oxygen permeability coefficient. The measurement results are shown in Tables 1 and 2.

(2) Preparation of Outer Layer Resin Composition 100 parts by mass of IIR (butyl rubber "Exxon Butyl" 268 manufactured by ExxonMobil Chemical Company), 19 parts by mass of crosslinkable resin (silane-modified polypropylene "Linkron" (registered trademark) XPM800HM manufactured by Mitsubishi Chemical Corporation), 19 parts by mass of polypropylene (propylene homopolymer "Prime Polypro" (registered trademark) J108M manufactured by Prime Polymer Co., Ltd.), 3 parts by mass of resin-based crosslinking agent (alkylphenol-formaldehyde resin "Hitanol" (registered trademark) 2501Y manufactured by Hitachi Chemical Co., Ltd.), 6 parts by mass of zinc oxide (zinc oxide type 3 manufactured by Seido Chemical Industry Co., Ltd.), and 5 parts by mass of antioxidant (Irganox 1010) were charged into a twin-screw kneading extruder (manufactured by The Japan Steel Works, Ltd.) and kneaded at 235°C for 3 minutes. To the kneaded pellets, 2 parts by mass of a silanol condensation catalyst (silane crosslinker master batch "Catalyst MB" PZ010 manufactured by Mitsubishi Chemical Corporation) was added by dry blending to prepare an outer layer resin composition B1. The outer layer was extruded within 30 minutes after the addition of Catalyst MB.
BIMS (ExxonMobil Chemical Corp., brominated isobutylene-p-methylstyrene copolymer rubber "EXXPRO" (registered trademark) 3745) 100 parts by mass, PA12 (Ube Industries, Ltd., polyamide 12 "UBE NYLON" (registered trademark) 3012U) 39 parts by mass, zinc oxide (Seido Chemical Industry Co., Ltd., zinc oxide 3 types) 5 parts by mass, 6PPD (Solutia Corp., phenylenediamine-based antiaging agent "SANTOFLEX" ( Three parts by mass of N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (registered trademark) 6PPD, one part by mass of calcium stearate (calcium stearate SC-PG manufactured by Sakai Chemical Industry Co., Ltd.), and one part by mass of stearic acid (industrial stearic acid manufactured by Chiba Fatty Acid Co., Ltd.) were charged into a twin-screw kneading extruder (manufactured by The Japan Steel Works, Ltd.) and kneaded at 235°C for three minutes to prepare outer layer resin composition B2.

(3) Production of refrigerant transport hose The thermoplastic resin composition prepared in (1) above was extruded by an extruder onto a mandrel that had been previously coated with a release agent into a tubular shape having a thickness shown in Tables 3 and 4. A polyester reinforcing thread was braided on top of this using a braiding machine, and outer layer resin composition B1 or B2 was extruded by an extruder onto this into a tubular shape having a thickness shown in Tables 3 and 4, and the mandrel was removed to produce a hose consisting of an inner layer/reinforcing layer/outer layer.
The hoses thus produced were evaluated for refrigerant permeation resistance and flexibility. The evaluation results are shown in Tables 3 and 4.

The measurement and evaluation methods are as follows:

[Measurement of breaking elongation (EB)]
The thermoplastic resin composition was molded into a sheet having an average thickness of 1.0 mm using a 40 mmφ single-screw extruder equipped with a 200 mm wide T-type die (manufactured by Plagiken Co., Ltd.) under conditions of a cylinder and die temperature set to the melting point of the polymer component with the highest melting point in the thermoplastic resin composition + 10°C, a cooling roll temperature of 50°C, and a take-up speed of 3 m/min. The molded sheet was punched out into a JIS No. 6 dumbbell shape to prepare test pieces of the thermoplastic resin composition.
The test pieces of the prepared thermoplastic resin composition were subjected to a tensile test in accordance with JIS K7161 at a temperature of 25°C, a relative humidity of 50%, and a speed of 500 mm/min. The elongation at break was determined from the obtained stress-strain curve, and this elongation was designated as the break elongation (EB).

[Measurement of EB Residual Rate after Treatment]
A JIS No. 6 dumbbell-shaped test piece of the thermoplastic resin composition prepared for measuring the breaking elongation was sealed in a constant volume container together with water, refrigerating machine oil, and a refrigerant, and subjected to a heat treatment at a predetermined temperature for a predetermined time. The amounts of the water, refrigerating machine oil, and refrigerant contained were in a mass ratio of 1:80:160.
After the treatment, a test piece of the thermoplastic resin composition was taken out of the constant volume container, and the elongation at break of the test piece was measured, which was defined as the EB after the treatment.
For the test piece of the untreated thermoplastic resin composition, the breaking elongation was measured, and this was defined as pre-treatment EB.
The EB remaining rate after treatment was calculated by the following formula.
EB remaining rate after processing (%)=EB after processing/EB before processing×100

[Measurement of 10% modulus]
The thermoplastic resin composition was molded into a sheet having an average thickness of 1.0 mm using a 40 mmφ single-screw extruder equipped with a 200 mm wide T-type die (manufactured by Plagiken Co., Ltd.) under conditions of a cylinder and die temperature set to the melting point of the polymer component with the highest melting point in the thermoplastic resin composition + 10°C, a cooling roll temperature of 50°C, and a take-up speed of 3 m/min.
The prepared sheets having an average thickness of 1.0 mm were punched out into a JIS No. 6 dumbbell shape, and a tensile test was carried out in accordance with JIS K7161 at a temperature of 25°C, a relative humidity of 50%, and a speed of 500 mm/min. From the obtained stress-strain curve, the stress at 10% elongation was determined, and this was taken as the 10% modulus.

[Measurement of oxygen permeability coefficient]
The thermoplastic resin composition was molded into a sheet having an average thickness of 0.2 mm using a 40 mmφ single-screw extruder equipped with a 200 mm wide T-type die (manufactured by Plagiken Co., Ltd.) under conditions of a cylinder and die temperature set to the melting point of the polymer component with the highest melting point in the thermoplastic resin composition + 10°C, a cooling roll temperature of 50°C, and a take-up speed of 3 m/min.
The prepared sheet was cut out, and the oxygen permeability coefficient was measured at a temperature of 21° C. and a relative humidity of 50% using OXTRAN 1/50 manufactured by MOCON Corporation.

[Evaluation of refrigerant permeability resistance]
Measurements were performed in accordance with SAE J2064 AUG2015. A test sample of a hose with a length of 1.07 m was filled with 70% ± 3% of refrigerant (HFO-1234yf) ^per 1 cm3 of the internal volume of the test sample. The test sample was left in an atmosphere of 80 ° C. for 25 days, and the mass loss per day (refrigerant permeation amount) [kg / day] during the last predetermined period (5 days to 7 days) during the 25-day period was measured, and the value obtained by dividing this loss by the inner surface area of the test sample was converted to a value per year to calculate the refrigerant permeability coefficient [kg / (m ² · year)]. The smaller the value of the refrigerant permeability coefficient, the better the refrigerant permeability resistance. If this value is 6 or less, it can be evaluated as having sufficient refrigerant permeability resistance for practical use. In Tables 3 and 4, the value is indicated as ◯ when it is 6 or less, and × when it is more than 6.

[Flexibility evaluation]
As shown in Fig. 2, one end of the hose test sample S in the longitudinal direction is fixed by a fixture such as a clamp, and a spring balance is attached to the other end separated from the fixed position by a predetermined length L (120 + hose outer diameter / 2) x π [mm] and pulled, bending the test sample S in a semicircular arc from the state shown by the broken line to the state shown by the solid line. The tensile force F measured by the spring balance pulling the test sample S in the horizontal direction in the bent state with the hose inner radius R of 120 mm was used as an evaluation index. The smaller the value of this tensile force F, the easier the test sample S is to bend and the more flexible it is. In Tables 3 and 4, the case where the tensile force F is less than 20 N is indicated by ◯, and the case where the tensile force F is 20 N or more is indicated by x.

Examples 12 to 19 and Reference Examples 1 to 3
[raw materials]
BIMS: Brominated isobutylene-p-methylstyrene copolymer rubber "EXXPRO" (registered trademark) 3745 manufactured by ExxonMobil Chemical Corporation
SIBS: Kaneka Corporation's isobutylene-based thermoplastic elastomer "SIBSTAR" (registered trademark)
6PPD: Solutia's phenylenediamine-based antioxidant "SANTOFLEX" (registered trademark) 6PPD (substance name: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine)
Zinc oxide: Three types of zinc oxide manufactured by Seido Chemical Industry Co., Ltd. (zinc oxide mixed with polyamide 6 as a master batch with the zinc oxide content listed in the table)
PA6: Polyamide 6 "UBE Nylon" (registered trademark) 1011FB manufactured by Ube Industries, Ltd.
PA6/12: Polyamide 6/12 copolymer "UBE Nylon" (registered trademark) 7024B manufactured by Ube Industries, Ltd.
PA11: Polyamide 11 "Rilsan" (registered trademark) OTL manufactured by Arkema Co., Ltd.
Hydrotalcites: Hydrotalcite "DHT" (registered trademark)-4C (specific surface area: 15 m ² /g) manufactured by Setras Holdings Co., Ltd.
Stearic acid: Industrial stearic acid manufactured by Chiba Fatty Acid Co., Ltd. Calcium stearate: Calcium stearate SC-PG manufactured by Sakai Chemical Industry Co., Ltd. (melting point: 155±5°C)
Zinc stearate: Zinc stearate SZ-PG (melting point: 125±5°C) manufactured by Sakai Chemical Industry Co., Ltd.
Magnesium stearate: Magnesium stearate SM-PG (melting point: 145±5°C) manufactured by Sakai Chemical Industry Co., Ltd.

(1) Preparation of Thermoplastic Resin Composition The materials described in the conditions in Table 5 were charged into a twin-screw kneader (Japan Steel Works, Ltd.) in the blending ratios shown in each example, and kneaded for 3 minutes at 200 to 225° C. The kneaded product obtained was continuously extruded into a strand shape, and cut with a cutter after cooling with water to obtain a thermoplastic resin composition in the form of pellets.

(2) Film Molding The obtained thermoplastic resin composition was molded into a sheet using a 40 mmφ single screw extruder with a 200 mm wide T-shaped die (Pla Giken Co., Ltd.) Specifically, the cylinder and die temperatures were set to 200 to 240° C., and the cooling roll temperature and take-up speed were set to arbitrary conditions to obtain a sheet with an average thickness of 1.0 mm.

[Measurement of 10% modulus]
The obtained sheet was punched out into a JIS No. 6 dumbbell shape and subjected to a tensile test in accordance with JIS K7161 at a temperature of 25°C and a speed of 500 mm/min. The stress at 10% elongation was determined from the obtained stress-strain curve and was taken as the 10% modulus.

[Measurement of oxygen permeability coefficient]
The obtained sheet was cut out, and the oxygen permeability coefficient ^cm3 ·mm/( ^m2 ·day·mmHg) was measured at a temperature of 21° C. and a relative humidity of 50% using an OXTRAN 1/50 manufactured by MOCON Corporation.

[Measurement of kneading energy]
When producing a thermoplastic resin composition, the specific energy of the twin-screw kneader, i.e., the power consumption of the extruder motor (kWh/kg) taking into account the motor efficiency and mechanical efficiency of the kneader per kg of raw materials in kneading, was measured and used as the kneading energy.

[Measurement of EB Residual Rate after Treatment]
The obtained sheet was punched out into a JIS No. 6 dumbbell shape to prepare a test specimen.
The test pieces were subjected to a tensile test in accordance with JIS K7161 at a temperature of 25°C, a relative humidity of 50%, and a speed of 500 mm/min. The elongation at break was determined from the obtained stress-strain curve, and this elongation was defined as the elongation at break before treatment (EB).
Next, the thermoplastic resin composition was treated in a refrigerant-containing composition containing a refrigerant, a refrigerating machine oil and water at 150° C. for 96 hours, and then the breaking elongation (post-treatment EB) was measured in a tensile test.
The EB residual rate was calculated according to the following formula.
EB remaining rate (%)=EB after processing/EB before processing×100

The manufacturing conditions and measurement results are shown in Table 5 below. Note that in Table 5, the values of the 10% modulus, oxygen permeability coefficient, kneading energy, and EB residual rate after treatment for each example are not measured values but are listed as relative values when the measured value in Reference Example 1 is set to 100.

The present disclosure includes the following inventions.
Invention [1] A thermoplastic resin composition for a refrigerant transport hose, having an island-sea structure in which an elastomer exists as domains in a matrix containing a thermoplastic resin, the thermoplastic resin composition comprising 100 parts by mass of an elastomer, 30 to 100 parts by mass of a thermoplastic resin, and 0.5 to 10 parts by mass of a hydrotalcite and/or a magnesium-aluminum solid solution, the thermoplastic resin comprising 50 to 100 parts by mass of a polyamide based on 100 parts by mass of the thermoplastic resin, and the elastomer comprising an elastomer having a polyisobutylene skeleton.
Invention [2] The thermoplastic resin composition for a refrigerant transport hose according to Invention [1], wherein the thermoplastic resin composition comprises at least one selected from the group consisting of zinc oxide, a phenylenediamine-based or quinoline-based antioxidant, and a processing aid.
Invention [3] The thermoplastic resin composition for a refrigerant transport hose according to Invention [1] or [2], wherein the polyamide is at least one selected from the group consisting of polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 6/66 copolymer, polyamide 6/12 copolymer, polyamide 46, polyamide 6T, polyamide 9T and polyamide MXD6.
Invention [4] The thermoplastic resin composition for a refrigerant transport hose according to any one of Inventions [1] to [3], wherein the elastomer having a polyisobutylene skeleton is at least one selected from the group consisting of butyl rubber, halogenated butyl rubber, isobutylene-monoalkylstyrene copolymer rubber, halogenated isobutylene-monoalkylstyrene copolymer rubber, and styrene-isobutylene-styrene block copolymer.
Invention [5] The thermoplastic resin composition for a refrigerant transport hose according to any one of Inventions [1] to [4], wherein the hydrotalcites and/or magnesium-aluminum solid solution have a specific surface area of 100 m ² /g or more.
[6] The thermoplastic resin composition for a refrigerant transport hose according to any one of inventions [1] to [5], further comprising a first fatty acid metal salt and a second fatty acid metal salt having a melting point lower than that of the first fatty acid metal salt.
[7] The thermoplastic resin composition for a refrigerant transport hose according to invention [6], wherein the melting point of the first fatty acid metal salt is 150°C or higher.
[8] The thermoplastic resin composition for a refrigerant transport hose according to the invention [7], wherein the melting point of the second fatty acid metal salt is less than 150°C.
[9] The thermoplastic resin composition for a refrigerant transport hose according to any one of inventions [6] to [8], wherein the first fatty acid metal salt is 0.5 to 5.0 parts by mass based on 100 parts by mass of the elastomer.
[10] The thermoplastic resin composition for a refrigerant transport hose according to any one of inventions [6] to [9], wherein the second fatty acid metal salt is 0.5 to 5.0 parts by mass based on 100 parts by mass of the elastomer.
[11] The thermoplastic resin composition for refrigerant transport hose according to any one of inventions [6] to [10], wherein the ratio Wd1/Wd2 of the mass Wd1 of the first fatty acid metal salt to the mass Wd2 of the second fatty acid metal salt is 0.5 to 5.0.
[12] The thermoplastic resin composition for a refrigerant transport hose according to any one of inventions [6] to [11], wherein the first fatty acid metal salt is at least one selected from the group consisting of calcium stearate, zinc 12-hydroxystearate, and lithium 12-hydroxystearate.
[13] The thermoplastic resin composition for a refrigerant transport hose according to any one of inventions [6] to [12], wherein the second fatty acid metal salt is at least one selected from the group consisting of zinc stearate and magnesium stearate.
Invention [14] A refrigerant transport hose comprising a layer made of the thermoplastic resin composition according to any one of inventions [1] to [13].
Invention [15] The refrigerant transport hose according to invention [14], comprising an inner layer, a reinforcing layer and an outer layer, the inner layer being a layer made of the thermoplastic resin composition according to any one of inventions [1] to [13].
Invention [16] The refrigerant transport hose according to invention [14] or [15], which does not include a layer made of vulcanized rubber.

The thermoplastic resin composition of the present invention can be suitably used for the manufacture of refrigerant transport hoses.

REFERENCE SIGNS LIST 1 refrigerant transport hose 2 inner layer 3 reinforcing layer 4 outer layer F tensile force L specified length R hose inner radius S test sample

Claims (16)

A thermoplastic resin composition for a refrigerant transport hose having an island-sea structure in which an elastomer exists as domains in a matrix containing a thermoplastic resin, the thermoplastic resin composition containing 100 parts by mass of an elastomer, 30 to 100 parts by mass of a thermoplastic resin, and 0.5 to 10 parts by mass of a hydrotalcite and/or a magnesium-aluminum solid solution, the thermoplastic resin containing 50 to 100 parts by mass of a polyamide based on 100 parts by mass of the thermoplastic resin, and the elastomer containing an elastomer having a polyisobutylene skeleton. The thermoplastic resin composition for a refrigerant transport hose according to claim 1, wherein the thermoplastic resin composition contains at least one selected from the group consisting of zinc oxide, phenylenediamine-based or quinoline-based antioxidants, and processing aids. The thermoplastic resin composition for a refrigerant transport hose according to claim 1, wherein the polyamide is at least one selected from the group consisting of polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 6/66 copolymer, polyamide 6/12 copolymer, polyamide 46, polyamide 6T, polyamide 9T and polyamide MXD6. The thermoplastic resin composition for a refrigerant transport hose according to claim 1, wherein the elastomer having a polyisobutylene skeleton is at least one selected from the group consisting of butyl rubber, halogenated butyl rubber, isobutylene-monoalkylstyrene copolymer rubber, halogenated isobutylene-monoalkylstyrene copolymer rubber, and styrene-isobutylene-styrene block copolymer. 2. The thermoplastic resin composition for a refrigerant transport hose according to claim 1, wherein the hydrotalcites and/or magnesium-aluminum solid solution have a specific surface area of 100 m ² /g or more. The thermoplastic resin composition for a refrigerant transport hose according to claim 1, further comprising a first fatty acid metal salt and a second fatty acid metal salt having a melting point lower than that of the first fatty acid metal salt. The thermoplastic resin composition for a refrigerant transport hose according to claim 6, wherein the melting point of the first fatty acid metal salt is 150°C or higher. The thermoplastic resin composition for a refrigerant transport hose according to claim 7, wherein the melting point of the second fatty acid metal salt is less than 150°C. The thermoplastic resin composition for a refrigerant transport hose according to claim 6, wherein the first fatty acid metal salt is 0.5 to 5.0 parts by mass based on 100 parts by mass of the elastomer. The thermoplastic resin composition for a refrigerant transport hose according to claim 6, wherein the second fatty acid metal salt is 0.5 to 5.0 parts by mass based on 100 parts by mass of the elastomer. The thermoplastic resin composition for a refrigerant transport hose according to claim 6, wherein the ratio Wd1/Wd2 of the mass Wd1 of the first fatty acid metal salt to the mass Wd2 of the second fatty acid metal salt is 0.5 to 5.0. The thermoplastic resin composition for a refrigerant transport hose according to claim 6, wherein the first fatty acid metal salt is at least one selected from the group consisting of calcium stearate, zinc 12-hydroxystearate, and lithium 12-hydroxystearate. The thermoplastic resin composition for a refrigerant transport hose according to claim 6, wherein the second fatty acid metal salt is at least one selected from the group consisting of zinc stearate and magnesium stearate. A refrigerant transport hose comprising a layer made of the thermoplastic resin composition according to claim 1. The refrigerant transport hose according to claim 14, comprising an inner layer, a reinforcing layer and an outer layer, the inner layer being a layer made of the thermoplastic resin composition according to claim 1. The refrigerant transport hose according to claim 14, which does not include a layer made of vulcanized rubber.

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