Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Patent
1991-09-04
1994-02-15
Sluby, P. C.
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
428409, 428420, 428520, 4273722, 472 90, B32B 2708, B32B 704, B05D 302
Patent
active
052865517
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a material to pave skating rinks suitable for skates provided with blades. More particularly the invention relates to a material characterized by a chemical composition gradient between the upper skating surface and the inner surfaces.
BACKGROUND ART
As is known to those skilled in the field, the blade-skate skating dynamics requires that the skating surface be substantially grooved by the skate blades in order to balance the centrifugal forces generated during the movements which are typical of this sport. Thus it is indispensable that the sheeting regains the original smoothness after a certain time of use.
The smoothness of an ice surface is restorable by means of melting at relatively low costs. However, excepted the territories having a particularly cold climate, and in such territories during the warmer season, the maintenance of vast frozen surfaces involves very high investments and fixed maintenance expenses.
Owing to the above, skating rinks have been studied, which are made of synthetic materials such as Teflon (polytetrafluoroethylene), polyethylene, mixtures which include linear polyesters, the purpose being to reduce the initial investment and fixed maintenance expenses with respect to ice rinks, where ice is formed and maintained by means of cryogenic plants.
However, the surface of said materials, once it is worn out by skating, can only be restored by mechanical removal (by means of milling) of the worn out layer.
In particular, the polyethylene rinks, although they are the most economic, are quite unsatisfactory because the optimum maneuverability of blade-skates, which is only obtainable through a sufficient grooving, requires a substantial material removal for its restoration, which has proven to be uneconomical.
An improvement, as regards the problem of the costs involved in the restoring of the worn out skating surface, is disclosed in German patent application DE 3445976, which claims a water-repellent skating sheeting consisting of a mixture of saturated hydrocarbons.
In particular such sheeting is based on a mixture of waxes, polymers and copolymers of ethylene, propylene, butylene and mixtures thereof, having a melting point ranging from 30.degree. C. to 130.degree. C.
The materials in question are referred to, in the present specifications, as "Low-Melting Materials" or briefly "LMM". The "LMM" permit to restore the smoothness of the surface worn out by the skates by melting only the layer affected by wearing.
Such materials, however, are characterized by a high thermal expansion coefficient and exhibit poor mechanical properties; in particular a narrow elastic range, a low tensile strength, and a ductile/brittle transition temperature above 0.degree. C.
Such characteristics make it extremely difficult to prepare a smooth surface, free from cracks and splits.
This is due to the fact that, in manufacturing the skating sheeting, during the cooling from the melting temperature to the room temperature, the tensions resulting from the material shrinking cause cracks in several areas.
In order to solve said problems, the above-mentioned patent application claims a paving process consisting in laying preformed LMM tiles, i.e. already freely shrunk from the solidification temperature to the room temperature, onto particular porous substrates of inorganic nature, to which they anchor, thereby forming a prevailingly mechanical bond with said substrates.
A first problem connected with the practical use of pavings of the type claimed in the abovesaid patent application is encountered when the temperature of the LMM substrate complex drops and remains for a long time at values below -2.degree. to -3.degree. C. Under these conditions, many tiles get detached from the substrate, thus rendering the works unrealiable.
Another problem is connected with the formation and propagation of macroscopic cracks at temperatures also of a few degrees above 0.degree. C., which are caused either by frequent temperature fluctuations around such values or by the
REFERENCES:
patent: 5141816 (1992-08-01), Walker et al.
Di Stefano Vittorio
Marini Paolo
Skitech S.r.l.
Sluby P. C.
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