HEAT-RECOVERABLE WRAPPING WITH DIMPLES

EMBALLAGE THERMO-RETRACTABLE GARNI D'EXCROISSANCES

English Abstract

ABSTRACT
A heat-recoverable material in stressed condition
with a plurality of irregularities on the outer surface adapted
to disappear on recovery of the material. Preferably the
irregularities are protuberances pushed out from the material
and a coating of heat-fusible sealant fills the corresponding
depressions.

Claims

The embodiments of the invention for which an exclusive
property or privilege is claimed are as follows:-
1. A protective wrapping of cross-linked
material which has been dimensionally changed from a
heat stable form to a dimensionally heat unstable form
throughout its thickness with a plurality of
irregularities on the outer surface formed by mechanical
or hydraulic means, which material is capable of
returning to its original heat stable form, with
disappearance of the irregularities solely by the
application of heat.
2. A protective wrapping according to Claim 1,
in which the irregularities are protuberances defined
by depressions on the inner surface, a layer of heat-
fusible sealant on the inner surface of the material
filling the depressions.
3. A protective wrapping comprising a flexible
sheet or tape of cross-linked material which has been
dimensionally changed from a heat stable form to a
dimensionally heat unstable form throughout its
thickness with a plurality of protuberances on the outer
surface defined by depressions on the inner surface
formed by mechanical or hydraulic means, which material
is capable of returning to its original form with
disappearance of the irregularities solely by the
application of heat and a layer of heat-fusible sealant
on the inner surface of the material filling the
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depressions.
4. A method of making a protective wrapping
comprising a flexible sheet or tape of cross-linked
material which has been dimensionally changed from a heat
stable form to a dimensionally heat unstable form
throughout its thickness with a plurality of protuberances
on the outer surface defined by depressions on the inner
surface which material is capable of returning to its
original form with disappearance of the irregularities
solely by the application of heat and a layer of heat-
fusible sealant on the inner surface of the material
filling the depressions by deforming the material by
mechanical or hydraulic means when dimensionally changed
from the heat stable form to the dimensionally heat
unstable form to produce the depressions and protuberances
and coating the inner surface with the heat-fusible
sealant.
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Description

: ` 1067165 8698
The invention relates to a protective wrapping -
of heat-recoverable material.
According to the invention there is provided a
protective wrapplng of cross-llnked materlal which has
been dimensionally changed from a heat stable form to a
dimensionally heat unstable form throughout its
thickness with a plurality of irregularities on the
outer surface formed by mechanical or hydraulic means,
whlch material is capable of returning to lts original
heat stable form, with disappearance of the
irregularities solely by the applicatlon of heat.
More specifically, there is provided a
: protective wrapping comprising a flexible sheet or tape
of cross-linked material whlch has been dimensionally
lS changed from a heat stable form to a dimenslonally heat
unstable orm throughout lts thlckness with a plurality
of protuberances on the outer surface defined by
depressions on the inner surface formed by mechanical
or hydraulic means, which material ls capable of
returning to its original form with disappearance of
the irregularities solely by the application of heat
;- and a layer of heat-fusible sealant on the inner surface
of the material filling the depressions.
The invention includes a method of making a
protecti~e wrapping as described above by deforming the
material by mechanical or hyd~aulic means when
dimensionally changed from a heat stable form to a
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~ 8698
1~67165
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dimensionally heat unstable form to produce the
depresslons and protuberances and coating the inner
surface with heat-fuslble sealant.
A specific example of a protective wrapping
according to the lnvention wlll now be descrlbed wlth
reference to the accompanying drawings ln which:-
Flgures 1 and 2 are perspective view of a wirespllce during applicatlon and heat treatment of the
wrapping of heat-recoverable material according to the
invention;
Figure 3 ls a cross-sectional view of the heat-
recoverable material on the wire prior to recovery;
Figure 4 is a view similar to Figure 3 after
heat treatment and recovery; and
Flgure 5 ls a cross-sectlonal view of the heat-
recoverable material applied to a wire during heat
treatment.
A protective wrapping of heat-recoverable tape
18 is made from a suitable material such as hydrocarbon
that has been cross-linked and deformed (e.g. by
stretching longltudlnally). The tape is embossed to
define protuberances 26 on the outer surface 24 and
' corresponding depressions or dimples on the inner surface
; which i5 coated with a layer of heat-fusible sealant
; 25 20 which completely fills the dimples. The meltlng point
of the sealant is approxlmately the temperature required
for recovering or shrinking the tape.
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: 106716S 8698
In use, the tape may be wrapped around a splice
between wires 10 and 12 which may have previously been
wrapped with adhesive vinyl tape 16. A strip of waxed
paper 28 is peeled from the sealant during application
of the tape to the splice. The tape is then treated
with heat 32 from a heat source 34 relieving the
internal stresses in the tap and permitting recovery of
; its pre-deformed dimension. A correct amount of heat
~; melts the sealant during recovery and the protuberances
also shrink leaving a smooth outer surface on the tape
which can be seen or felt by the operator to indicate
that recover~ and sealant flow is complete. Thus,
application of excessive heat causing destruction of
the materlal can be avolded. The protuberances provide
a gap 36 between overlapplng portions of tape ventlng
alr from between sealant 20 and the wire during the
appllcation of heat.
In preparation of the material, after cross-
`~ llnking and deformatlon by conventional means, the
sealant, if used, is applied to the inner surface, e.g.
; by lamination. A roll bar having protuberances is
pressed against the sealant to form the dimples ensuring
that each dimple is completely filled with sealant.
An advantage of the example is that the
protuberances disappear only after sufficient heat has
been applied throughout the material and the sealant.
In addition, complete recovery can be ascertained by
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8698
1(~67165
an operator merely by touch so that the material can
be used where the light level is low, for example in
manholes.
A suitable polyer for the material is an alpha-
olefin sold under the "SURLYN A 1650 (Trade Mark) and a
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suitable sealant is a copolyamide "TERLAN 1510" (Trade
Mark).
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