PRODUCTION OF FOAM PLASTICS FROM HIGH MOLECULAR WEIGHT OLEFIN POLYMERS

1382070 Expanded crystalline olefin polymers BADISCHE ANILIN- & SODA-FABRIK AG 26 May 1972 [29 May 1971] 24886/72 Heading C2C Expanded plastics material are made from a high molecular weight olefin polymer whose X- ray crystallinity at 25‹ C. is more than 50% by weight by mixing polymer at a tem...

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Hauptverfasser: TATZEL H,DT, BECK G,DT
Format: Patent
Sprache:eng
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Zusammenfassung:1382070 Expanded crystalline olefin polymers BADISCHE ANILIN- & SODA-FABRIK AG 26 May 1972 [29 May 1971] 24886/72 Heading C2C Expanded plastics material are made from a high molecular weight olefin polymer whose X- ray crystallinity at 25‹ C. is more than 50% by weight by mixing polymer at a temperature which is from 50‹ to 100‹ C. above the crystallite melting point of the olefin polymer and at a shear rate of from 20 to 200 seconds-1 at superatmospheric pressure with an unsubstituted or halosubstituted aromatic hydrocarbon, the mixture is introduced into a zone in which it is homogenized at a temperature of from the crystallite melting point of the polymer to a maximum of 50‹ C. above the same and at a shear rate of from 500 to 1500 seconds-1 with, as expanding agents from 5 to 40% by weight based on the olefin polymer of an aliphatic hydrocarbon and/or a halo-substituted aliphatic hydrocarbon whose boiling point at a pressure of 760 torr. is from 30‹ to 200‹ C. below the crystallite melting point of the olefin polymer, at a pressure which prevents expansion of the mixture, to form a gel, the gel is then cooled under superatmospheric pressure to a temperature which is from 10‹ to 60‹ C. below the crystallite melting point of the olefin polymer and it is then forced into a zone in which a pressure prevails which is lower than the vapour pressure of the expanding agent in the gel. In the examples, crystalline polyethylene or polypropylene was mixed with tale or barium stearate and then with (i) xylene, toluene or benzene, and optionally polyisobutylene and (ii) n-heptane, n-pentane, n-butane, iso-butane- and/or isopentane and optionally polyisobutylene or a copolymer of isobutylene and vinyl ether, under the above conditions and the mixture was extruded to form expanded strands which were cut into particles. The particles may be kept under heat and pressure to completely expand them and then heated in a mould and sintered together by compression.