Rubber composition for hose production, hose, and process for producing refrigerant hose

A refrigerant hose comprising at least two layers of an inner tube and a reinforcing layer on the exterior of the inner tube, said inner tube of the hose being fabricated from a rubber composition comprising

• (A) 100 parts by weight of a brominated copolymer of a C4-7 isomonoolefin and a p-alkylstyrene wherein p-alkylstyrene content is 5 to 25% by weight, bromine content is at least 1.5% by weight, and the weight ratio of bromine unit to p-alkylstyrene unit is such that 0.15<bromine/p-alkylstyrene<0.40;
• (B) 0.1 to 10 parts by weight of zinc white;
• (C) 1 to 15 parts by weight of brominated alkylphenol resin;
• and
• (D) 20 to 150 parts by weight of talc as an inorganic laminar compound wherein the hose has a refrigerant gas impermeability of less than 8.0 mg.mm/24 hr.cm2 and has a compression set resistance of up to 50% after being subjected to 25% compression at 120° C. for 70 hours and a compression set resistance of up to 70% after being subjected to 25% compression at 150° C. for 70 hours.

A process for producing a refrigerant hose comprising at least two layers of an inner tube and a reinforcing layer on the exterior of the inner tube, wherein said inner tube is fabricated from a rubber composition comprising

• (A) 100 parts by weight of a brominated copolymer of a C4-7 isomonoolefin and a p-alkylstyrene where p-alkylstyrene content is 5 to 25% by weight, bromine content is at least 1.5% by weight, and the weight ratio of bromine unit to p-alkylstyrene unit is such that 0.15<bromine/p-alkylstyrene<0.40;
• (B) 0.1 to 10 parts by weight of zinc white;
• (C) 1 to 15 parts by weight of brominated alkylphenol resin;
• and
• (D) 20 to 150 parts by weight to talc as an inorganic laminar compound wherein the hose has a refrigerant gas impermeability of less than 8.0 mg.mm/24 hr.cm2 and has a compression set resistance of up to 50% after being subjected to 25% compression at 120° C. for 70 hours and a compression set resistance of up to 70% after being subjected to 25% compression at 150° C. for 70 hours;
• said inner tube being formed by an in-die drawing method wherein a drawing ratio (a/b) of the cross-sectional area at the die inlet (a) to the cross-sectional area of the extrudate at the die outlet (b) is at least 5.