Multilayer plastic pipe

A method for transporting a petrochemical substance, comprising flowing said petrochemical substance through a multilayer plastic pipe, which comprises:

• (I) an outer layer comprising a moulding composition based on polyamide;
• (II) a first intermediate layer adjacent to the outer layer comprising a moulding composition based on a mixture of:
• (a) from 95 to 99% by weight based on the total weight of said layer (II), of a linear crystalline polyester, and
• (b) from 1 to 5% by weight, based on the total weight of said layer (II), of a compound having at least two isocyanate groups,
• wherein the isocyanate groups originating from component (IIb) are present in the mixture of (IIa) and (IIb) in a concentration of from 0.03 to 0.3% by weight;
• (III) a second intermediate layer adjacent to the first intermediate layer comprising a moulding composition based on polyamide,
• (IV) a third intermediate layer adjacent to said second intermediate layer and an inner layer comprising a moulding composition comprising a mixture of:
• (a) from 50 to 90% by weight of the polyamide, and
• (b) from 10 to 50% by weight of a poly(alkyl)acrylic ester;
• and
• (V) an inner layer comprising a moulding composition based on polyvinylidene fluoride;
• and
• wherein each of said layers (I) to (V) is adhesively bonded to the respectively adjacent layer.

A method for transporting brake, cooling and hydraulic fluids or fuel in a motor vehicle comprising flowing said fluid or fuel through a multilayer plastic pipe, which comprises:

• (I) an outer layer comprising a moulding composition based on polyamide;
• (II) a first intermediate layer adjacent to the outer layer comprising a moulding composition based on a mixture of:
• (a) from 95 to 99% by weight, based on the total weight of said layer (II), of a linear crystalline polyester, and
• (b) from 1 to 5% by weight, based on the total weight of said layer (II), of a compound having at least two isocyanate groups,
• wherein the isocyanate groups originated from component (IIb) are present in the mixture of (IIa) and (IIb) in a concentration from 0.03 to 0.3% by weight;
• (III) a second intermediate layer adjacent to the first intermediate layer comprising a moulding composition based on polyamide;
• (IV) a third intermediate layer adjacent to the second intermediate layer and an inner layer comprising a moulding composition comprising a mixture of:
• (a) from 50 to 90% by weight of a polyamide, and
• (b) from 10 to 50% by weight of poly(alkyl)acrylic ester;
• and
• (V) an inner layer comprising a moulding composition based on polyvinylidene fluoride;
• and
• wherein each of said layers (I) to (V) is adhesively bonded to the respectively adjacent layer.

A hollow article, comprising a multilayer plastic pipe, which comprises:

• (I) an outer layer comprising a moulding composition based on polyamide;
• (II) a first intermediate layer adjacent to the outer layer comprising a moulding composition based on a mixture of:
• (a) from 95 to 99% by weight, based on the total weight of said layer (II), of a linear crystalline polyester, and
• (b) from 1 to 5% by weight, based on the total weight of said layer (II), of a compound having at least two isocyanate groups,
• wherein the isocyanate groups originating from component (IIb) are present in the mixture of (IIa) and (IIb) in a concentration of from 0.03 to 0.3% by weight;
• (III) a second intermediate layer adjacent to the first intermediate layer comprising a moulding composition based on polyamide;
• (IV) a third intermediate layer adjacent to said second intermediate layer and the inner layer comprising a moulding composition comprising a mixture of:
• (a) from 50 to 90% by weight of a polyamide, and
• (b) from 10 to 50% by weight of a poly(alkyl)acrylic ester;
• and
• (V) an inner layer comprising a moulding composition based on polyvinylidene fluoride;
• and
• wherein each of said layers (I) to (V) is adhesively bonded to the respectively adjacent layer.

A motor vehicle filling port or tank, comprising a multilayer plastic pipe, which comprises:

• (I) an outer layer comprising a moulding composition based on polyamide;
• (II) a first intermediate layer adjacent to the outer layer comprising a moulding composition based on a mixture of:
• (a) from 95 to 99% by weight, based on the total weight of said layer (II), of a linear crystalline polyester, and
• (b) from 1 to 5% by weight, based on the total weight of said layer (II), of a compound having at least two isocyanate groups,
• wherein the isocyanate groups originating from component (IIb) are present in the mixture of (IIa) and (IIb) in a concentration of from 0.03 to 0.3% by weight;
• (III) a second intermediate layer adjacent to the first intermediate layer comprising a moulding composition based on polyamide;
• (IV) a third intermediate layer adjacent to the second intermediate layer and the inner layer comprising a moulding composition comprising the mixture of:
• (a) from 50 to 90% by weight of a polyamide, and
• (b) from 10 to 50% by weight of a poly(alkyl)acrylic ester;
• and
• (V) an inner layer comprising a moulding composition based on polyvinylidene fluoride;
• and
• wherein each of said layers (I) to (V) is adhesively bonded to the respectively adjacent layer.