Moldable silane-crosslinked polyolefin foam beads
AssigneeValcour Incorporated
InventorsThomas M. Pontiff, Frederick H. Collins
Life of this patent
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Abstract
Moldable foam beads comprising a silane-crosslinked polyolefin foam are produced by mixing a composition comprising a silane-modified polyolefin (such as a silane-grafted polyethylene) and a silanol condensation catalyst in an extruder to produce a melt, then injecting a blowing agent into the melt at a rate effective to produce a desired foam density in the extrudate; extruding and cutting the melt to form foam beads; and exposing the foam beads to moisture to produce silane crosslinking of the polyolefin foam.
Claims15
A process of producing moldable foam beads comprising a silane-crosslinked polyolefin foam, comprising the steps of:
- (a) mixing a composition comprising a silane-modified polyolefin and a silanol condensation catalyst in an extruder to produce a melt;
- (b) injecting a blowing agent into said melt at a rate effective to produce the desired foam density in the extrudate;
- (c) extruding and cutting said melt to form foam beads, and
- (d) exposing said foam beads to moisture to produce silane crosslinking of the polyolefin foam.
A process of producing moldable foam beads comprising a silane-crosslinked polyolefin foam, comprising the steps of:
- (a) mixing a composition comprising a silane-modified polyolefin, a silanol condensation catalyst and a solid blowing agent in an extruder to produce a melt;
- (b) heating said melt to a temperature effective to activate said blowing agent;
- (c) maintaining the temperature of said melt at an acceptable foaming temperature at the die of said extruder;
- (d) extruding and cutting said melt to form foam beads;
- and
- (e) exposing said foam beads to moisture to produce silane-crosslinking of the polyolefin foam.
A process of producing moldable foam beads comprising a silane-crosslinked polyolefin foam, comprising the steps of:
- (a) mixing effective amounts of a composition comprising at least one polyolefin with a silane compound containing at least one unsaturated group, a free radical initiator and a silanol condensation catalyst in an extruder to produce a melt comprising a silane-modified polyolefin;
- (b) injecting a blowing agent into said melt at a rate effective to produce the desired foam density in the extrudate;
- (c) extruding and cutting said melt to form foam beads, and
- (d) exposing said foam beads to moisture to produce silane crosslinking of the polyolefin foam.
A process of producing moldable silane-crosslinked polyethylene foam beads, comprising the steps of:
- (a) mixing a composition comprising a silane-grafted low density polyethylene and a silanol condensation catalyst selected from the group consisting of organotin esters in an extruder to form a melt;
- (b) injecting a hydrocarbon or halogenated hydrocarbon blowing agent into said melt at a rate effective to cool said melt to foaming temperature and produce an extruded foam product having a density in the range of from about 1.5 to about 2.5 pcf;
- (c) extruding and cutting said melt to form foam beads, and
- (d) exposing the foam beads to moist ambient air to produce silane crosslinking of the polyethylene foam.
Dependencies are inferred from the claim text.