Hose for transporting refrigerant

1. A hose for transporting refrigerant comprising an inner tube layer including a gas barrier layer and a rubber layer adjacent to an outer surface of the gas barrier layer, wherein

the gas barrier layer comprises a polyamide resin composition comprising from 0.5 to 20 parts by mass of a hydrotalcite that is not surface treated per 100 parts by mass of a modified polyamide obtained by blending a polyamide and a carboxyl group-containing modified polyolefin;

the rubber layer comprises a rubber composition comprising from 1 to 15 parts by mass of an alkylphenol-formaldehyde resin per 100 parts by mass of a raw rubber and from 30 to 80 parts by mass of a carbon black per 100 parts by mass of the raw rubber;

the raw rubber comprises a BIMS, a butyl rubber and/or a halogenated butyl rubber, which is a copolymer rubber and, also, an EPDM (ethylene propylene diene terpolymer);

a content of the BIMS in the raw rubber is from 5 to 40 parts by mass, a total content of the BIMS and the copolymer rubber is from 20 to 80 parts by mass, and a content of the EPDM is from 80 to 20 parts by mass; and

the carbon black has an N 2 SA that is greater than or equal to 75 m 2 /g and a DBP dibutyl phthalate) absorption number that is greater than or equal to 90 cm 3 /100 g.

2. The hose for transporting refrigerant according to claim 1 , wherein the copolymer rubber is a halogenated butyl rubber.

3. The hose for transporting refrigerant according to claim 1 , wherein the polyamide is at least one selected from the group consisting of polyamide 6, polyamide 11, polyamide 12, polyamide 4-6, polyamide 6-6, polyamide 6-10, polyamide 6-12, polyamide MXD-6, and copolymers of two or more of these.

4. The hose for transporting refrigerant according to claim 1 , wherein the hydrotalcite is produced by calcining a raw hydrotalcite.

5. The hose for transporting refrigerant according to claim 1 , wherein an adhesive layer is not interposed between the gas barrier layer and the rubber layer.

6. The hose for transporting refrigerant according to claim 1 , wherein the gas barrier layer and the rubber layer are directly bonded.

7. The hose for transporting refrigerant according to claim 1 , wherein a reinforcing layer is provided on the inner tube layer and an outer tube layer is provided on the reinforcing layer.

8. The hose for transporting refrigerant according to claim 1 , wherein the hydrotalcite is Mg 1−x Al x O 3.83x where 0.2≦x≦0.5.

9. The hose for transporting refrigerant according to claim 1 , wherein a sheet is fabricated at a temperature of 230° C. using the polyamide resin composition, a sample having a width of 5 mm, a length of 80 mm, and a thickness of 0.15 mm is cut from the sheet and used as a sample, and a Young's modulus of the sample when measured at a tensile speed of 50 mm/minute in accordance with JIS (Japanese Industrial Standard) K 7161 is 300 MPa or less.

10. The hose for transporting refrigerant according to claim 1 , wherein a refrigerant-containing composition comprising a refrigerant and a lubricant is used therein, and the refrigerant is a fluorine-based compound containing double bond or a saturated hydrofluorocarbon.

11. The hose for transporting refrigerant according to claim 1 , wherein a mass ratio of the polyamide to the carboxyl group-containing modified polyolefin is from 85/15 to 65/35.

12. The hose for transporting refrigerant according to claim 1 , wherein an amount of the hydrotalcite is from 3 to 15 parts by mass per 100 parts by mass of the modified polyamide.

13. The hose for transporting refrigerant according to claim 1 , wherein a mixing temperature is from 200° C. to 280° C.

14. The hose for transporting refrigerant according to claim 1 , wherein a Young's modulus of the polyamide resin composition after hardening is 270 MPa or less.

15. The hose for transporting refrigerant according to claim 1 , wherein a thickness of the gas barrier layer is from 0.05 to 0.20 mm and wherein a content of a p-alkylstyrene in the BIMS is from 5 to 10 mass %.