Stock material or miscellaneous articles – Structurally defined web or sheet – Physical dimension specified
Patent
1993-05-19
1995-11-21
Ryan, Patrick J.
Stock material or miscellaneous articles
Structurally defined web or sheet
Physical dimension specified
428245, 428286, 428292, 428302, 428339, 428364, 4284744, 428484, 428910, 526 73, 521919, 264280, 26433117, 264348, 2642104, 156324, B32B 900
Patent
active
054685435
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention concerns a process for producing a strip of ski coating material made of polyethylene of ultra high molecular weight and a ski coating made by this process and its application.
STATE OF THE ART
The essential properties of a ski running-surface coat are resistance to abrasion and wax acceptance. The resistance to abrasion is determined prevailingly by the molecular weight of the polyethylene whereas the wax acceptance depends on the polyethylene density and hence on the crystal proportion in this polyethylene.
In order to meet the strength requirements of the ski industry regarding polyethylene ski coats, polyethylene of high molecular weight has been processed; this entails polyethylenes of ultra high molecular weights which can be processed only in a restricted number of ways. A preferred procedure of the ski industry is press-sintering. The blocks so made are further worked by peeling into strip-shaped ski-coatings.
The Japanese disclosure Hei 3-215,280 describes a procedure for further processing these ski-coating strips. Lengths of material cut to the corresponding ski lengths are heated in a discontinuous procedure and cooled in an immersion bath, as a result of which the ratio of amorphous to crystal portions in the polyethylene of ultra high molecular weight are set in such a way that the ski coating shall well accept wax. However this procedure incurs the drawback that warping arises at the surfaces of the ski coating on account of rapid cooling, and after finishing in the form of stretching is therefore necessary.
DISCUSSION OF THE INVENTION
The object of the invention is to create a simple process which can be carried out in only a few steps to manufacture a ski-coating strip polyethylene of ultra high molecular weight and allowing to so adjust the crystal portion in the final ski-coating that it shall evince not only high resistance to abrasion but also optimal gliding properties.
This problem is solved in the process of the invention in that a ski-coating strip made by screw extrusion, by ram extrusion or press sintering with ensuing peeling first is uniformly raised to a temperature above 140.degree. C. by continuously moving it through a heating zone and then is uniformly cooled by continuously moving it through a cooling zone to a temperature equal to or lower than ambient.
This process ensures thereby improvement of ski-coating materials made in conventional manner and which are the subject to ever higher requirements by the ski industry regarding especially wax acceptance and ski gliding behavior on snow.
In an advantageous embodiment mode of the invention, the process is characterized in that the ski-coating strip is 0.5 to 1.5 mm thick and is heated in the heating zone by infrared for 10 to 25 sec., preferably between 13 and 20 sec. Moreover the process of the invention is characterized in that the ski-coating strip material is cooled in the cooling zone to a temperature of 10.degree. to 20.degree. C., the cooling zone consisting at least in part of a cooled sizing system. This step is advantageous in that the ski-coating strip retains its smooth surface following cooling and that thereby the otherwise conventional surface-stretching can be eliminated following cooling. In another feature of the invention, it is characterized in that the dwell time of the ski-coating strip in the cooling zone is 8 to 30, preferably 10 to 25 sec.
The advantageous implementations of the process of the invention, such as controlled temperatures both in the heating and in the cooling zones and the dwell time of the ski material in the heating and cooling zones result in that the crystal structure of the initial ski-coating material can slowly disintegrate in the heating zone at a temperature above 140.degree. C. and in that recrystallization can be carried out thereupon in the cooling zone by means of controlled temperature and dwell time. The crystalline proportion of the ski coatings made by the process of the invention therefore can be adjusted in the most precise mann
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Bahta Abraham
Isosport Verbundbauteile Gesellschaft m.b.H.
Ryan Patrick J.
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