Loading patent…
AssigneeMitsui Petrochemical Industries, Ltd.
InventorsKazuo Yagi, Hitoshi Mantoku
Estimating the term…
If ultra-high-molecular-weight polyethylene having an intrinsic viscosity (.beta.) of at least 5 dl/g is grafted with a silane compound in the presence of a radical initiator and extrusion-molded and the extrudate is impregnated with a silanol condensation catalyst after or during drawing and is then exposed to water to effect crosslinking, there is obtained a novel molecularly oriented molded article in which increase of the melting temperature, which is not observed in conventional drawmolded or crosslinked molded articles of polyethylene, can be attained, and even if this molecularly oriented molded article is exposed to a temperature of 180.degree. C. for 10 minutes, the molded article is not fused but the shape is retained and even after this heat history, a high strength retention ratio can be maintained. In this draw-molded article, the adhesiveness and creep resistance are prominently improved while high elastic modulus and high tensile strength inherent to a drawmolded article of ultra-high-molecular-weight polyethylene are retained.
A process for the preparation of a molecularly oriented, silane-cross-linked ultra-high-molecular-weight polyethylene molded article, which comprises (i) melt-kneading a mixture of (a) an ultra-high-molecular-weight polyethylene having an intrinsic viscosity (.eta.) of at least 5 dl/g, (b) 0.1 to 10 parts by weight, per 100 parts by weight of the component (a), of a silane compound having both of a radical-polymerizable organic group and a hydrolyzable organic group, (c) 0.01 to 3 parts by weight, per 100 parts by weight of the component (a), of a radical initiator and 9900 to 33 parts by weight, per 100 parts by weight of the component (a), of a diluent, (ii) melt-extruding the resultant kneaded composition through a spinneret or a die to form an undrawn molded article, (iii) subjecting the obtained undrawn molded article of the silane-grafted ultra-high-molecular-weight polyethylene to a drawing treatment so that the drawn molded article has an orientation degree(F) of at least 0.90, (iv) impregnating the molded article with a silanol condensation catalyst during or after the drawing step (iii), and (v) contacting the drawn molded article impregnated with the catalyst with water to effect cross-linking.
A process for the preparation of a molecularly oriented, silane-cross-linked ultra-high-molecular-weight polyethylene molded article, which comprises (i) melt-kneading a mixture of (a) an ultra-high-molecular-weight polyethylene having an intrinsic viscosity (.eta.) of at least 5 dl/g, (b) 0.1 to 10 parts by weight, per 100 parts by weight of the component (a), of a silane compound represented by the following formula:
Dependencies are inferred from the claim text.