The present invention relates a method or process for obtaining a
plate, preferably a composite plate, of vulcanized rubber, particularly for obtaining
shoe soles, having "pull-up" features, i.e. they undergo chromatic changes when
subjected to mechanical stress, such as bending or traction.
Such a method is suitable for rubber plates, particularly composite
plates, and soles obtained from them and designed to be subjected to a number of
working processes, e.g. die-cutting, milling and/or under edge trimming, to give
thereto a non-flat shape at predetermined portions of the sole, e.g. at the plantar
arch, and/or to obtain a peripheral rim "raising" slightly upward towards a shoe
upper all along a sole edge, e.g. as disclosed in the Italian patent application
VR2003A000096, filed on August 05, 2003 entitled "Composite robber plate" in the
name of the applicant of the present invention.
The main object of the present invention is to provide a method of
obtaining rubber plates, in particular composite rubber plates, from which a plurality
of shoe soles can be obtained by die-cutting that can undergo a desired chromatic
effect on the surface thereof during subsequent working operations.
Another object of the present invention is to provide a method suitable
for ennobling a rubber plate and thus any shoe soles obtained therefrom.
Another object of the present invention is to provide a method relatively
easy and inexpensive to be carried out, whereby not substantially affecting the
production costs of a rubber sole.
According to a first aspect of the present invention, there is provided
a method of obtaining a rubber plate, which includes providing and heat vulcanizing
at least one layer comprising a number of different mixtures, whereby obtaining
a tape or plate and is characterized in that it comprises
- applying at least one layer of spreadable finishing product suitable for providing
a so-called pull-up effect onto at least one surface of said plate or tape thus
obtained, and
- applying mechanical stress to said plate or to a shoe sole obtained therefrom
through die-cutting to determine a desired chromatic change of said pull-up effect
product.
Advantageously, the layer or layers of the pull-up effect product
comprises a solution of waxes and oils or a dispersion of waxes or a varnish.
According to another aspect of the present invention, there is provided
a rubber plate or sole obtained by the method according to the present invention
and suitable for providing chromatic variation effects obtained by applying mechanical
stresses to the plate or sole.
Further features and advantages of the present invention will better
appear from the following detailed description of presently preferred embodiments
thereof, given below by way of non-limiting examples on how to carry out the present
invention.
Example 1
A composite plate of vulcanized rubber was prepared and a coat or
layer of an Arz-3-33 product, i.e. a varnish, (a solution of oils and waxes or a
dispersion of hydrosoluble waxes), manufactured and commercialised by the company
Stahl Itatia S.p.A. at Arzignano - Vicenza - Italy, was spayed directly onto the
rubber plate. By subjecting the plate to a bending and/or pulling and/or compression
action, a pull-up effect, i.e. a change of colour tonality or a permanent brightening
in the mechanically stressed portion of the plate, is obtained.
The same effect is obtained by mechanically stressing a shoe sole
obtained from a rubber composite plate as processed in the above described manner
and subjected to a trimming operation.
Example 2
A composite plate (two layer with different hardness) of vulcanized
rubber having an overall thickness of 4 mm was produced. On such a plate a layer
comprising 74% of transparent varnish Idropol 4417 manufactured by the company Polaris
S.r.l. at Thiene - Vicenza - Italy, and 25% of Nero Special, manufactured by the
company SIC S.p.A at Robbecchetto - Milan - Italy, was applied by spreading by means
of an engraved-surface roll. Idropol 4417 is a transparent bright resin that when
coloured with a Nero Special pigment generates a smooth and bright black primer.
The varnish was allowed to dry and while making use of a roll with
an engraved surface a second layer of the above-mentioned Arz-3-33 varnish was spread
onto it.
The second layer of varnish was allowed to dry and then a semi-bright
finished surface with pull-up effect was obtained. When the surface is subjected
to a bending stress, one obtains a brightening effect of grey tonalities.
Example 3
A vulcanized rubber composite plate having a thickness of 3 mm was
produced. On this plate a layer of Idropol 44004 Nero varnish, manufactured by the
company Polaris S.r.l. was applied. When such a layer was dried, a second layer
of varnish comprising 90% Arz-3-33 and 10% Ocra dye, manufactured by SIC S.p.A was
applied onto it by means of a roll having an engraved surface.
The second layer of varnish was also allowed to dry and, using again
an engraved surface roll, a third layer of Idropol 44017 was applied which produced
a bright and transparent finish.
After drying of the third layer, a plate having a surface with a bright
finish was obtained showing a light yellow brightening, when subjected to mechanical
stress.
Example 4
The procedure of the Example 3 was repeated, but a mono-layer plate
of vulcanised rubber was used, thus obtaining the same results as in the Example
3.
The invention as described above is susceptible to numerous modifications
and variations within its scope as defined by the claims.
