| 摘要 |
<p>1466408 Extruding ethylene oxide polymer UNION CARBIDE CORP 5 Dec 1974 [10 Dec 1973] 52698/74 Headings B5A and B5B [Also in Divisions C3 and A5] The moulding of a molten ethylene oxide polymer, e.g. by extrusion, injection moulding, blow moulding, or slot casting, is facilitated by the blending with the polymer of a fugitive moulding aid comprising 4 to 200 parts by weight of water, per 100 parts of polymer, to obtain a melt flow index of 0À05 to 20 decigrams per minute, under specified conditions. The water permits lower extrusion pressure and evaporates from the moulding, e.g. to 2% by weight of a film continuously produced by inflation of an extruding tube, and thereby produces a cooling effect. Preferred ranges are 10 to 20 parts of water, and 0À1 to 10 decigrams per minute melt flow index. The polymer may be a homopolymer of ethylene oxide, or a copolymer with propylene, or butylene, or styrene oxide. In the examples, a homopolymer of specified molecular weight was blended with specified percentages of water on a two roll mill, and cut into pieces which were extruded; (I)-(III), to produce films by inflation of a tube issuing from the extruder die; (V), to produce a monofilament which was then uniaxially stretched at a 7À8 to 1 ratio; (VI) to produce a tube using an air cooled mandrel. Extrusion is effected at a polymer temperature of 55‹ to 120‹ C., and the extruded product may be a sheet. The polymer may have a weight average molecular weight of 250,000 to 5,000,000, and may contain a dye, a stress cracking, or oxidation, or heat, or ultra violet stabilizer, a surfactant and/or a filler. The films obtained by inflation of an extruded tube may be of a density of 1À0 to 1À2 gm./cc., and may be made into uniaxially oriented tapes of higher tensile strength. The unoriented films may be made into a bag for containing a toxic water dispersible powder, e.g. an insecticide, fungicide, or bactericide, the bag being enclosed within an outer bag of water insensitive polyethylene, polypropylene, polystyrene, or vinyl chloride resin, the outer bag being removed and the inner bag being inserted in water to disintegrate and permit the powder to dissolve.</p> |
