Process for manufacturing composite flexible hose

A process for manufacturing a composite flexible hose comprising;

• (A) forming an innermost layer by extruding, in a tubular form, a modified polyamide obtainable by a blend of a polyamide and a carboxyl-containing modified polyolefin,
• (B) forming an intermediate rubber layer by extruding, directly onto an outer surface of the innermost layer, a rubber composition obtainable by a blend of a rubber material, 10 to 50 parts by weight of one of silicic acid and a salt thereof and 5 to 15 parts by weight of a brominated alkylphenol formaldehyde resin per 100 parts by weight of the rubber material, the rubber material is obtainable by a blend of butyl rubber and a halogenated butyl rubber at a weight ratio of 50/50 to 0/100,
• (C) forming a fibrous reinforcement layer on an outer surface of the intermediate layer without vulcanizing the intermediate layer,
• (D) forming an external rubber layer on the fibrous reinforcement layer by means of extrusion molding, and
• (E) vulcanizing all laminated layers, provided that there is no adhesive layer between the innermost layer and the intermediate layer.

A composite flexible hose consisting essentially of an innermost layer, an intermediate rubber layer on the innermost layer, a fibrous reinforcement layer on the intermediate layer and an external rubber layer on the fibrous reinforcement layer;

• the innermost layer comprising a modified polyamide obtained by blending a polyamide and a carboxyl-containing modified polyolefin;
• the intermediate rubber layer comprising a rubber composition obtained by blending a rubber material, 10 to 50 parts by weight of one of silicic acid and a salt thereof and 5 to 15 parts by weight of a brominated alkylphenol formaldehyde resin per 100 parts by weight of the rubber material;
• and the rubber material is obtained by blending butyl rubber and a halogenated butyl rubber at a weight ratio of 50/50 to 0/100;
• and the hose is obtained by vulcanizing after formation of the innermost, intermediate and external layers, and has no adhesive layer between the innermost layer and the intermediate rubber layer.