Polyamide hose for compressed air

1. A multilayer hose for compressed air, having only 3 layers, in this order:

an outer layer (1) consisting of polyamide, and optionally a plasticizer, an impact modifier or a catalyzed, different polyamide,

an intermediate layer (2) consisting of ethylene copolymer(s) or propylene copolymer(s) having a flexural modulus of less than 500 MPa, and

an inner layer (3) of a polymer having a flexural modulus of greater than 1100 MPa, the inner layer (3) being in contact with compressed air, wherein said inner layer polymer (3) is polycarbonate (PC), polyphenyene sulfide (PPS), polyphenylene oxide (PPO) or an aromatic polyamide or a semiaromatic polyamide,

wherein the polyamide of the outer layer (1) is:

PA11,

PA12,

a polyamide A corresponding to the formula X,Y/Z or 6,Y2/Z, in which:

X denotes the residues of an aliphatic diamine having from 6 to 10 carbon atoms,

Y denotes the residues of an aliphatic dicarboxylic acid having from 10 to 14 carbon atoms,

Y2 denotes the residues of an aliphatic dicarboxylic acid having from 15 to 20 carbon atoms,

Z denotes at least one unit that is residues of a lactam, residues of an α,ω-aminocarboxylic acid or the unit X1, Y1 in which X1 denotes the residues of an aliphatic diamine and Y1 denotes the residues of an aliphatic dicarboxylic acid,

the ratios by weight Z/(X+Y+Z) and Z/(6+Y2+Z) being between 0 and 15%, or

a semiaromatic polyamide B.

2. The hose as claimed in claim 1 , wherein polyamide A of the outer layer is PA 6,14, PA 6,18 or PA 10,10.

3. The hose as claimed in claim 1 , wherein polyamide B of the outer layer is PA 6,I/6,T, PA 6,6/6,I/6,T, PA 6/6,T, PA 11/10,T, PA 12/12,T, PA 10,10/10,T or PA 10,I/10,T.

4. A multilayer hose for compressed air having only 3 layers, in this order:

an outer layer (1) consisting of polyamide, and optionally a plasticizer, an impact modifier or a catalyzed, different polyamide,

an intermediate layer (2) consisting of ethylene copolymer(s) or propylene copolymer(s) having a flexural modulus of less than 500 MPa, and

an inner layer (3) consisting of three adjacent layers successively composed of a layer of polymer having a flexural modulus of greater than 1100 MPa, of a braid and of a layer of polymer having a flexural modulus of greater than 1100 MPa, in which said layer of polymer having a flexural modulus of greater than 1100 MPa is polycarbonate (PC), polyphenyene sulfide (PPS), polyphenylene oxide (PPO) or a polyamide that is PA 6, PA 6,6, PA 6,10, PA 6,12, an aromatic polyamide or a semiaromatic polyamide,

wherein the polyamide of the outer layer (1) is:

PA11,

PA12,

a polyamide A corresponding to the formula X,Y/Z or 6,Y2/Z, in which:

X denotes the residues of an aliphatic diamine having from 6 to 10 carbon atoms,

Y denotes the residues of an aliphatic dicarboxylic acid having from 10 to 14 carbon atoms,

Y2 denotes the residues of an aliphatic dicarboxylic acid having from 15 to 20 carbon atoms,

Z denotes at least one unit that is residues of a lactam, residues of an α,ω-aminocarboxylic acid or the unit X1, Y1 in which X1 denotes the residues of an aliphatic diamine and Y1 denotes the residues of an aliphatic dicarboxylic acid,

the ratios by weight Z/(X+Y+Z) and Z/(6+Y2+Z) being between 0 and 15%, or

a semiaromatic polyamide B.

5. The hose of claim 1 , wherein said semi-aromatic polyamide B of the outer layer (1) corresponds to the formula X/Y, AR, in which:

Y denotes the residues of an aliphatic diamine having from 8 to 20 carbon atoms,

Ar denotes the residues of aromatic dicarboxylic acid,

X either denotes the residues of aminoundecanoic acid NH 2 —(CH 2 ) 10 —COOH, of lactam 12 or of the corresponding amino acid, or denotes the unit Y,x, the residue of the condensation of the diamine with an aliphatic diacid (x) having between 8 and 20 carbon atoms, or denotes the unit Y,I, the residue of the condensation of the diamine with isophthalic acid.