Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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,
~AMINATED BODY, MORE ~SP~CIAL~Y
CONVEYOR ~LT OR DRIVING BE~T
The present invention relates to a strip or
web-like pliable laminated body made of rubber or
rubber~ e elastomeric material having metal rein-
forcing plies, more especially conveyor belts or
driving belts reinforced with steel wires, cables,
braids or the like, embedded therein and extending
substantially longitudinally therethrough.
The protection of the metal reinforcing
plies in industrial rubber and plastics material
articles against corrosive influences of the outer
atmosphere is a problem which, under different
provisions and conditions, repeatedly occurs and
despite far-reaching expenditures in individual
cases, does not always find satisfactory solutions.
A complete protection in the region of the elastomeric
material surrounding the plies is not always
generally obtainable in practice. It is difficult
to attain a complete, continuous envelopment of the
metal reinforcing plies over the whole of their
surfaces by adhesion to the elastomeric material.
~urther, a source of mechanical damage to the cover
layers or plates occurs by dynamic stress to the
article, whereby penetrating dampness finds cracks,
etc. through which to enter into the interior of the
article. The corrosion damage created thereby is
not, however, localised, but travels along the plies
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and, depending upon their nature, also continues
over long distances, so that without any external
effects initially being noticeable, extensive des-
truction can occur. Particularly endangered in this
respect are conveyor belts with embedded steel
wires, cables, braids or strands as reinforcing
plies. The plies which as a result of their structure
are comprised of a plurality of individual wires of
predetermined relative looseness and having a highly
fissurised surface and cavities extending into the
core, renders impossible the complete, enclosed
envelopment aimed at as ideal with adhesive bonding
to the elastomeric material by known techniques.
~here has been no lack of attempts to obtain a
thorough "through bonding" of the rubber or plastics
material in the core, for example, by prior impreg-
nation of the steel wires with rubber solution,
enveloping individual wires or braids with a plastics
mixture, insertion of a plastics component when
laying the wires, and others. All the endeavours in
this direction have never achieved more than partial
success.
It is an object of the present invention to
protect the metal reinforcing plies in dynamically
stressed rubber and plastics material articles,
whilst maintaining their bonding with the material
in which they are embedded 9 effectively against
corrosive influences of the outer atmosphere, in
~11955~)
first place against the penetration of moisture. Whilst
this problem is of special importance to so-called "steel
wire" conveyor belts and power transmission belts having
steel wires or the like filamentary metal reinforcing plies,
the present invention however, is not restricted exclusively
thereto, but to a large extent is also applicable to other
pliable laminated bodies used industrially.
The present invention provides a flexible laminated
body made of an elastomeric material mixture and having at
least one metal reinforcing ply embedded therein and extending
1~ substantially longitudinally therethrough, in which the or
each metal reinforcing ply is adhesively bonded, at least
along portions of its surface, with the surrounding elastomeric
material mixture, and in which the or each metal reinforcing
ply is coated with an anti-corrosion agent comprising a component
of the elastomeric material mixture.
Preferably, the anti-corrosion agent comprises a
processing aid and/or a plasticiser for the elastomeric
material mixture. Depending upon the type and nature of the
embedding material, the anti-corrosion agent may comprise a
paraffin or naphtha-based mineral oil, a chloroparaffin or a
liquid organic ester or ether compound, or the like.
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11195SO
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In any case, the anti-corrosion agent
preferably contains marked water-repellent components.
~iquid anti-corrosion agents for the surface
treatment of freely suspended, or otherwise used in
exposed arrangement, tension cables are known as
such. Within the scope of the present problem, the
use of such conventional anti-corrosion agents formed
from an oil, wax or vaseline base were not
considered because a serious impairment of the adhesive
bond between the wires and the surrounding material
was to be expected therefrom.
The solution provided by the present
invention, taken against all practical experiences,
concerning the preliminary treatment of the metal
reinforcing plies leads to surprisingly favourable
results, which showed a substantially reduced
susceptibility to corrosion and a simultaneously
improved dynamic proficiency of the plies, and which
also subject to vigorous bending change stresses,
e.g. of a steel wire conveyor belt was consistent
during continuous testing. The reasoning behind the
successful results obtained is probably due t~ the
combination of individual effects which are
important on their own; firstly, the elastomeric
material mixture is able in its flow phase to penetrate
deeply between the individual wires; secondly, also
the finest remaining cavities are filled with a water-
repellent agent at the same time as a lubricant which
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stops the direct metal sliding friction between the
wires; and finally the covering endlessly enclosing
the steel wires, regardless of their surface shape,
provides a reliable protection against moisture
penetrating through fissures and other damage points,
into the embedding material. The protective effect
provided already before the processing of the plies
is to be appreciated as an additional advantage.
The invention provides for perfect compatab-
ility between the anti-corrosion agent and the
composition of the elastomeric material mixtures, so
that it also absorbed at the intended bonding points ¦
by the mixtures. Its applicability therefore does
not require any changes in the conventional mixture
structure.
The present invention will be further
illustrated, by way of example, with reference to the
accompanying drawing, in which the single ~igure
shows a cross-section through a portion of a steel
wire conveyor belt.
The conveyor belt shown is built up in known
manner ~rom an upper and a lower cover plate 1 and
2 and a core layer 3 containing steel wires 4 as
reinforcing plies extending longitudinally therethrough
and mutually spaced relative to each other. Whilst
the two cover plates 1 and 2 in consideration of
mechanical stresses, are formed from an abrasion-
resistant, strong rubber mixture, the inner cor
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layer 3 is formed of material which will bond to
both the cover plates 1 and 2 and to the embedded
steel wires 4. : .
The steel wires 4 are coated with a flowable
anti-corrosion agent comprising a naphtha-based
oil which, in the drawing, is denoted by the reference
numeral 5.
