Crosslinked tubular foam
AssigneeHalcor S.A.
InventorsIoannis Biris, George Hinopoulos
Life of this patent
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Abstract
There is provided an insulation foam in a tubular form, comprising at least one seamless layer of crosslinked polyethylene (PEX) closed-cell physical foam. The tubular foam can favourably be used to thermally insulate tubes that convey water, refrigerants or other fluids, in particular, copper tubes for Heating, Ventilation, Air-Conditioning and Refrigeration (HVAC&R) applications, as well as plastic tubes for use in domestic plumbing systems, hydronic radiant heating and cooling systems. There is also provided a method for manufacturing a crosslinked polyethylene (PEX) closed-cell physical foam in seamless tubular form, an insulation foam material using the same and a polymer blend for its manufacturing.
Claims16
A method for manufacturing a crosslinked polyethylene (PEX) closed-cell physical foam in seamless tubular form, wherein the method comprises the steps of:
- i) feeding an extruder with raw materials or a mixture thereof, wherein the raw materials or the mixture thereof comprises a polyethylene base resin, a crosslinking agent and a crosslinking catalyst as crosslinking means, a cell regulator, a cell regulator additive, a cell stabilizer, a cell stabilizer additive and an antistatic agent, and optionally a color agent or masterbatch, a fire-resistant additive and one or more other additives;
- ii) feeding foaming gas inside the extruder, adjusting the volume of the gas to obtain a desired foam density, and maintaining a pressure within the extruder to prevent premature foaming upon homogenizing the mixture of melt and blowing gas by the action of the extruder screw, wherein the foaming gas is injected into the extruder at a pressure of 40 to 70 bar and the pressure is maintained within the extruder to prevent premature foaming;
- iii) extruding the mix of materials through a corresponding die giving the desired tubular form, wherein the sudden pressure drop upon exit of the extrusion die leads to the formation of physical closed-cell foam;
- iv) optionally cooling the extruded physical closed-cell foam;
- and
- v) crosslinking the extruded physical closed-cell foam so as to attain a crosslinked polyethylene (PEX) physical closed-cell foam in seamless tubular form.
An insulation foam material in tubular form, which comprises a crosslinked polyethylene (PEX) closed-cell physical foam, wherein the crosslinked polyethylene (PEX) closed-cell physical foam has a seamless tubular form, a crosslinking density ranging from 8.0% to 15.0%, a foam density ranging from 28 to 36 kg/m3, and an average foam cell size ranging from 0.15 to 0.60 mm.
A polymer blend, comprising:
- 75.0 to 95.0 wt. % of a polyethylene base resin selected from at least one of LLDPE, LDPE, or HDPE;
- 0.75 to 4.0 wt. % of a crosslinking agent selected from at least one of silane crosslinker or trimethoxyvinylsilane;
- 0.1 to 2.0 wt. % of a crosslinking catalyst selected from at least one of organometallic tin compound or dibutyltin dilaurate;
- 0.5 to 3.0 wt. % of an antioxidant selected from at least one of hindered phenolic, phosphite, amine and silane-derived antioxidants, or a methyldecylpolysiloxane-based compound;
- 0.75 to 3.0 wt. % of a cell regulator selected from at least one of talc, clay, silica gel;
- 0.0.1 to 1.0 wt of a cell regulator additive selected from at least one of stearate salts or zinc stearate;
- 0.01 to 1.0 wt. % of an antistatic agent;
- 0.01 to 1.0 wt. % of a cell stabilizer selected from at least one of glycerol ester and amide compounds, stearamide-related compounds, or glycerol monostearate;
- 0.01 to 1.0 wt. % of a cell stabilizer additive selected from waxes or Montan wax;
- and
- 0.01 to 1.0 wt. % of a color agent.
Dependencies are inferred from the claim text.