초록

A jacket (3) for flexible heat-insulated conduits, in particular district heat transport lines, comprising a foamed or inflated polyethylene-based thermoplastic with a modulus of elasticity between 90 and 300 MPa and a density between 0.560 and 0.850 g/cm3.

대표청구항 ▼

What is claimed is: 1. A flexible heat-insulated conduit comprising: (a) an internal tube; (b) an insulating layer surrounding the internal tube; (c) an outer jacket surrounding the insulating layer, the outer jacket provided by a foamed or inflated polyethylene-based thermoplastic with a modulus o

What is claimed is: 1. A flexible heat-insulated conduit comprising: (a) an internal tube; (b) an insulating layer surrounding the internal tube; (c) an outer jacket surrounding the insulating layer, the outer jacket provided by a foamed or inflated polyethylene-based thermoplastic with a modulus of elasticity between 90 and 300 MPa and a density between 0.560 and 0.850 g/cm3. 2. The conduit according to claim 1, wherein the jacket is corrugated. 3. The conduit according to claim 2, wherein the thermoplastic is a low density polyethylene (LDPE). 4. The conduit according to claim 2, wherein the thermoplastic is a linear low density polyethylene (LLDPE). 5. The conduit according to claim 2, wherein the thermoplastic is a copolymer of ethylene. 6. The conduit according to claim 5, wherein the copolymer of ethylene is based on low density polyethylene. 7. The conduit according to claim 1, wherein the thermoplastic is a low density polyethylene (LDPE). 8. The conduit according to claim 1, wherein the thermoplastic is a linear low density polyethylene (LLDPE). 9. The conduit according to claim 1, wherein the thermoplastic is a copolymer of ethylene. 10. The conduit according to claim 9, wherein the copolymer of ethylene is based on low density polyethylene. 11. The conduit according to claim 1, wherein the foamed polyethylene-based thermoplastic has a degree of foaming between 10 and 60%. 12. The conduit according to claim 1, wherein the foamed polyethylene-based thermoplastic has cells with diameters between 0.1 mm and 0.5 mm. 13. A method for manufacturing a flexible heat-insulated conduit comprising the steps of: (a) providing an internal tube surrounded by an insulating layer; (b) producing a mixture of a polyethylene-based granulated material and a granulated material based on polyethylene into which a propellant has been mixed; (c) introducing the mixture into an extruder to produce a melt; and (d) extruding the melt through an extruder die to form a jacket over the insulating layer, the jacket being foamed up or inflated upon or after emergence from the extruder die. 14. The method according to claim 13, wherein the mixture of polyethylene-based granulated material and granulated material based on polyethylene into which a propellant has a ratio between 90:10 and 99:1. 15. The method according to claim 14, wherein the propellant in the granulated material is in the form of hollow spherules made of plastic.