Air brake line
View Patent ↗A pipe includes an outer layer composed of a molding composition which includes at least 40% by weight of a polyamide whose monomer units contain an average of at least 8 carbon atoms, and a layer composed of a polypropylene molding composition. An outer diameter of the pipe is in a range from 6 to 20 mm, a wall thickness of the pipe is in a range from 1.0 to 2.0 mm, and a thickness of the polypropylene layer is from 25 to 75% of the wall thickness. The pipe can be used as an air-brake line that can be produced at low cost, has high bursting strength, and has good low-temperature impact resistance.
1. An air-brake line, comprising:
a first layer comprising a polyamide molding composition comprising at least 40% by weight of a polyamide having monomer units including an average of at least 8 carbon atoms;
a second layer formed on the first layer, the second layer comprising an adhesion-promoting molding composition;
a third layer formed on the second layer so that the second layer is interposed between the first layer and the third layer, the third layer comprising a polypropylene molding composition;
a fourth layer formed on the third layer, the fourth layer comprising an adhesion-promoting molding composition; and
a fifth layer formed on the fourth layer so that the fourth layer is interposed between the third layer and the fifth layer, the fifth layer comprising a polyamide molding composition comprising at least 40% by weight of a polyamide having monomer units including an average of at least 8 carbon atoms;
wherein:
an outer diameter of the pipe is in a range from 6 to 20 mm;
a wall thickness of the pipe is in a range from 1.0 to 2.0 mm;
a thickness of the second layer is in a range of from 0.02 to 0.2 mm;
a thickness of the third layer is from 25 to 75% of the wall thickness; and
the polypropylene molding composition comprises a polypropylene having a melt flow rate (MFR) measured by ISO 1133 (230° C./2.16 kg) in a range of from 0.1 to 3 g/10 mm.
2. The air-brake line according to claim 1 , wherein:
the polyamide molding composition that forms the first layer further comprises at least one component selected from the group consisting of: impact modifiers, other thermoplastics, plasticizers, pigments, fillers, processing aids, flame retardants, glass fibers, antioxidants, UV stabilizers, and additives giving electrical conductivity or antielectrostatic properties to the layer (I); and
the polyamide forms a matrix of the polyamide molding composition of the first layer.
3. The air-brake line according to claim 1 , wherein the polyamide molding composition of the first layer comprises:
from 50 to 95 parts by weight of polyamide based on 100 parts by weight of the composition;
from 1 to 49 parts by weight of functionalized or unfunctionalized polyolefin based on 100 parts by weight of the composition; and
from 1 to 49 parts by weight of functionalized or unfunctionalized impact modifier based on 100 parts by weight of the composition.
4. The air-brake line according to claim 1 , wherein a modulus of elasticity of the polyamide molding composition of the first layer is from 300 to 800 MPa.