| abstract |
The present invention relates to a multilayer tube comprising, in its radial direction from the outside inwards: a polyamide outer layer (1); an inner layer (2) of a composition comprising, the total being 100%, 5 to 30% by weight of a blend (A) comprising: a polyethylene carrying epoxy functional groups, an impact modifier chosen from elastomers and very low density polyethylenes, the said impact modifier being completely or partly functionalized; 95 to 70% by weight of a blend (B) comprising: a fluoropolymer (B1), a functionalized fluoropolymer (B2), the proportion of (B2) being between 1 and 80% by weight of (A)+(B), the layers being successive and adhering to one another in their respective contact region. The inner layer is the layer in contact with the fluid being transported. According to one advantageous embodiment, a layer of functionalized polyolefin having functional groups capable of reacting with the functional groups of the fluoropolymer (B2) is placed between the layer (2) and the layer (3). The tube of the present invention has a very low permeability to the cooling liquid and to its additives (boric acid and its salts). These tubes also exhibit good resistance to fuels and to engine lubrication oils. This tube exhibits very good mechanical properties at low temperature and at high temperature. These tubes may be smooth or corrugated. The invention also relates to the use of these tubes for transporting cooling liquids. |