Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1()4~622
This in~ention relatss-to recoverable article~ especl- :
ally artlcles that are heat-racovorable and more especially
to articles ha~ing elastic msmory~ ~nd their U9~ o
Such articles haYe ~ow gained general aeceptance ~or
covering other articlas at joints or damaged portions ko
pro~ect them again~t mechanlcal damaga7 oorroslon~ to give
them electrical lnsulation~ prov~de electrical ~t~ess co~trol~
to ~onnect artlcles electr~cally and/or mechan~cally. Many
re¢ove~able artlcl~ are o~ a cro~slinXed thermoplast~c - -
10 materlalg or an elastomeric material~ and may be of a variety ~ :
e~ wall thicknesses and hence o~ variable rigidity or fle~
bility. Examples of proces~es o~ m~nu~acture and~u~es of
such articles are givan in UOS~ Patents ~osO 39086~242
3~2439211 and 3~297~8190 ;:
Ths recoverable artlcles frequ0ntly have the ~orm o~ :
heat shrinkable tube~ either closed or "wrap-around" - i.e.
ln sheet form with means ~or ~olning oppo~ite edges of the :
~heet to ~orm a closed tube a~ter it ha~ been wrapped around
a kedy hav~ng no available ~ree end~ The articles may, on ;`
20 the other hand~ be o~ a Y cros~-section i.e.~ in the ~orm o~ ~
a si~gle ~ube at one end and 2 tvr in some ca~e~ more) at the ~ :
otherO Further9 the artlcles ma~ be moulded to an~ of a
large number of shapesg wlth one or more open ends9 ~ut ln
general the articlss will have some llne~ not necessarily
~5 ~traight~ that can ~ regarded as an ~xis~ and directlon~ .-
parallel to th$s lln~ can be re~erre~ to as longitudinal or
axial~ The!~e directions ara in general tran~verse to the
dlrectlon ~f unrestrioted re¢o~ery of the article.
The articles are ~requently llned wlth matarials whlch
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have one or more o~ a number o~ properties - ~or ~:1cample~ the ~:
liner ma~ be a mastic, a cor~ta¢t adhesi~e, a hot melt adhe-
~l~re~ a soldera, which matarials may ba elactrlcally insulal;-
ing~ resisting~ or semi-conductlng all depending on the final
5 intonded use of the articl~
In the C~.~3 0~ art:lcles that are e~pan~blo~ for ~xample
heat. expanslble~ the "liner" will be pesitioned in the dir-
ect~ on of recovery, i .e ~, 9 en the outside of the articls i.
The previ~u~ly propo~ed articles havs suf~red a n~mber `:
o~ di~advant~ge~ in use, some being a3sociated with the need
for flexibility and the abllity to recover ovar Qubstrates
ha~ing v~ry dif~ersnt cross~sections at various po~nts longi-
tudi~ally spaced apart. Ixl order to achieve these alma~ the
material has to be relatively thin and where there are abrupt
¢hanges in cros~-se~tion of the substrat~ the materlal ma~
apl1t on shrinking otler the angle of the Ghange in cros~
seetion. Further~ such thin material offer~ in~u~icient
protection to the ~ubstrate~ becau~e of low meohanlcal
3t~ength and poor re#istance to torsion~ b~ndi~g or str~
It ha~ previouæly been proposed ~o reinforce heat re-
ooverable articles ~y incorporating braided or knltted
~brics that ~re coexten~ive with the articles; these rein-
forceme~ts have not found gen~ral use and are not of assl~t-
ance in meeting the pre~ent need.
~5 The pre~e~t inYention a¢cordingly provid~s a reoo~erable .
ar~icle ha~ing a plurallty o~ elongata rein~orcing member~
ly~ng generall~ parQllel to the lo~gitudinal axis o~ the
art~cle,
The longitudlnal axis i~ an axl~ tran~erse to the
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required direction of recovery of the artlcle,.
Preferably the me;nbers are metallio or flbre gla5s~ of
dlme~sions and having mechanlcal properties ~uch that in
general thsy do not total~ prevent recovery of the art~cle.
5 The members ma~ ba rods ~ strips ~ wlre~ ~ ribbon or ~ibres o~
~ny suitable ma~rial~ pre~erably spaeed apart on or ne~r the
inner sur~aee o~ the recoverable article and fres to move
their relati~re porti~ns on reco~rery. The mem~srs may be ~o
positloned and arranged wi~h respect to the ar~lcle that thay :~
10 do? or do not~ prevent or impcds recovery of the portien of
the oros~ ection of the article which they occupy. P'or ease ; -
o~ constructing the ar~icle~ the members may be ~olned by ~ ~ ;
interconnectirlg webs provided that such web~ do not impede :~
the r0covery o~ the articla or the relatitre movement of the
15 members where de~ired.
The article may also have a liner as de~cribed above~ :
and the members may be positloned on the inner surface ti.e.
the expo~ed surface, or the leading sur~ace in the direction
03E reeo~rery) of the li~ar~ ln ths liner~ between the li~er
and the recoverable article or withln ths article itsel~ tan
arra~geme~t that ~oes not~ of course~ require the u~e o~ a : ~ -
l~ner)~ In the latter case, the members may be po~ltioned .
be~ween two coax~al recoverable articles3 they may more
conveniantly be incorporated in a ~lngle reco~erable article
25 during l~s manufaeture~ for example ~y co-extrusion o~ the : `
plurallty o~ wire~ strips~ etc~ with the thermopla~tic or ~ :
other matexial o~ the reooverable artlcle. ~his method i~
most suitable whén the article i8 a tube.
Tha material o~ the ~ecoverable member, especially when
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it is heat~reco~erable~ may be any of those dlsclosed in U.S.
NoO 3~086~24~9 ~.e.~ generally c~os~-linXed cry~talllna
thermoplastic material; other materlalY lncluding elastomer~
are also suitable. As examples~ there may be mentionedg
cros~linked polyole~in~ eOg~ ethylene polymer~9 including
polyethylene~ ethylene/vinyl acetate~ ethylene/ethyl acrylate
copolymers, pol~butene, fluoropolym~rs~ e.g~ polyYinylidene
fluorlde7 and elastomers~ ~-gO~ tho~e mentioned in the U.S.
Patent No. 3~597~372.
The materlal~ may be crossllnked by radiation or by
chemical means. ~ :
The reinXorcing members may be metal~ e~g.~ copper~
~ra s~ aluminiuma or steel; they may be ribrs glass strips~
~or example polyester or epoxy flbre gla85 strips, or may be .
1~ o~ a plastics mat~rial~ e.gO~ polytetraf:Luorethylen~ or a .:
polyamide tnYlon)~ that do~s not melt at the reco~ery temp-
erature o~ the recoverable article,
As examples o~ polyamides that are e~poclally suitable~
: there may be mentioned ~romatic materials~ e.g.~ the conde~
sation products o~ m or ~ - phenylenediamine ~nd terephthal1¢
acid and the sel~-condensation product of p ~ aminobenzolc
acid. Thcre may also be u~ed m~mbar o~ other non - or high
~ meltlng sy~th~tic or natural materials9 e-gO~ oellulosio
materials (e.g~ ~otton) and Jute~ They may alternatlvely be ~ :
gla~s ~ibres or other f~bres with similar rein~orcing prop-
ertles. Alt~rna~tv~ly the article may be o~ integral con~
struction~ the relnforcement ln such ~a~e~ gener~lly takin~
the form o~ portions of cros3-sectlon thicker than the
remalnder of the reco~erable article.
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The articles of the i~vention have many uses; the ~n-
vention accordingly also provides methods of uslng the ;.
article~. It will be appreciated that some embodiments are
more suited for csr~aln usas than other~. For example~ a
tu~ular articl~ or ~leeve having aluminium wire~ or strip~
embedded in or on a hot melt adhesivs or a mastic is es~
pecially ~uitable for protecting and electrically lnsulating
a ~plice in a ~able9 for sxa~ple a telephone cable~ a power
cable or a ~oaxlal cable~ The splice i~ frsquently of larger
diameter than the cable in which it is madea e.g.~ twice the
diameter7 and thers is an angular shoulder to the splice ~ :
(which may be surrounded by a tubular case~ thereby maklng ; ~;
the diameter e~en larger and ~he ~houlder more abrupt). The - :
~leeve shrinks tightly around the bulky splice or its casa
and the adiacent cable; the rein~orcing strips or wires
causs ths transitlo~ of the recovared sleeve between the
larger and smaller portions to be a gentle curve. Thi~ con-
trasts with an unreinforced sleeve where the abrupt shoulder
gives a point of weakness where splltting is li~ely or a
possible loss o~ wall thicknes~ that renders the article vul-
nerable to mechanlcal damage when~ for example~ a trench ls
being ~llled. The rein~orcemen~ provldes the needed addl-
tional me¢hanical strength a~d resist~nce to bending~ torsion
or strass~
.A second pre~erred article according to the inYention
similar to that described in detall above but is suitable
for u~e when the splice described above has to be re-en~ered
~or ~epaixs or additions without every junotion being made.
Here~ the arti¢le usea i~ a "wrap-around" slee~e as defined
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above, for example, as described in U.S. Patent No.
3,45S,336 but otherwise similar in construction to
the first preferred tuhular sleeve~
Either of the two embodiments above may be
employed as a splice cover for high voltage cable,
for example as described in Raychem Limited~s British
- Patent Nov 1,434~71~ where materials suitable for
~aking the heat recoverable article are described. ~-
Where the heat recoverable material is semi-conducting,
it may have members e~g., wires, co-extruded wit~ it,
to aid in stress control.
The article may also be ~sed to encapsulate
bus-bars for use at hlgh voltages.
The dimensions of ~he rei~forcing members will
depend inter alia on the dimensions of the heat
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recoverable article, the degree ~f flexibility required,
the dimensions of the substrate to be dealt with and
the mechanical properties of all the materials concerned.
For a given application, however, it i9 a matter of
routine experiment to ascerta1n optimum values; it
i9 similarly a matter of such expeximent to determine
the optimum spacing and positioning details.
Several articles constructed in accordance
with the invention will now be described by way of
example only with reference to the accompanying
drawings, in w~ich: ~ -
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FIG. l illustrates in per~pective view a
closed tubular sleeve,
FIGo 2 illustrates a cross-section of a
wrap-around sleeve in open config-
uration, '
FIG. 3 illustrates a telephone splice pro- .
' técted by a tubular sleeve,
FIG. 4 illustrates a te~ephone splice and ., ~
. case similarly protected by a tubular ~ :
sleeve;
FIGSo 5 to 8 illustrate various possible :
. positions and configurations of
: reinforcement in a lined article,, a
portion only of which is shown,
; lS~ FI~. 9 illustrates:a portion of; an article
with a co-extruded reinforcement '
~:
before e~pansion and
PIG~ lO~il}ustra~es the~artlcle of Fig. 8 ,;:~
~ : after ex~ansio~. ' ~ :
20~ : Turning now to the drawings, and more
:
especially to Fig. 1, there is~illustrated:in Fig.
1 a heat-shrinka~le tube il~having disposed longit~ . -
udinally on its inner sùrface a plurality of spaced
reinforcing wires l2. The~se are retained in position
: 25: by any one of a variety of means. for:example by a
' thin layer of adhesive'or mastic (not shownl: as
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indicated above. On heating to cause recovery of
the tube 11 over a substrate or substratesO the
adhesive or mastic melts or softens allowing the
wires to be moved circum~erentially~ to become closer
- together, contact or overlap as the configuration
of the substrate or substrates demands.
Fig. 2 illustrates a section through a wrap-
around sleeve constructed in accordance with the
- invention. The recoverable member Z1 has integral
longitudinal rails 22g 23 in accordance with U.S.
Patent No~ 3~455,336, which when the article is
wrapped around a substrate will be contiguous and
joined by a channel as described in the U.S. Patent.
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~ Z 2 ~:
A layer of hot malt adhesive 24 i9 ap~lied to the ~urface of the
member 21 which in use abuts tha substrate. Embedded in the :~
~ree surface of the adhesive 24 are a plurality o~ matal
strlp~ ~5. In USe7 ~he portion 26 of the m0mber 21 khat ex- .:
tends keyond the rail 22 forms a ~lap that underlies the end
portion near the rail 23. A rein~orcing strlp 27 ls~ or two
or more such s~rips are, positloned on thi~ flap to reslst
shrinkage~ thereby maintaining the flap in contac~ with the
underside o~ the sleeve margin during recovery. The strip
10 or strlps 27 may be~ for exampleg of glass ~lbre rods. ~.
Referring now to Figs~ 3 and 4~ there are shown pro-
teoted 8plices in multiway telephone cables 33, ~3. In ~ig.
3t individual conductors 34~ o~ whlch only a ~ew are shown
~or clarity~ a~e ~pllced~ as by a heat shrinkable sleeve
aontaining solder 35~ indicated diagrammaticallyt The dia~
meter o~ ~he ~undle o~ spliced conductor,s 3~ is much greater
~han th~t of the cable 33~ and a heat shrunk article 31
according to the invention has a corre pondingly larger dia- :
m~ter where i~ protects the splice than where lt seals and
protec~ the J acket o~ tho cable 33 . Metal strlps 32 pro - :
duce a graflual transition between the two diameters.
The sf~ect of the metal strip 32 is evon more apparent
ln Fig. 4~ where ~ spliae case 45 is lnterposed betw~en the
spli¢e itsel~ and the ~hrink~ble ar~icle 31. In the ab~ence
o~ metal strips9 the heat shr~nkable member would recov~r
sharply around the ends 46 o~ the case 45 and be llable to
damage or splitti~g.
Turni~g now to Flgs~ ~ to 8~ there are illustrated
~ections th~ ugh various const~uctions according to the
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invantlon~ employing a recoverable member 51 and a mastic 52~ -
In Fig. 5~ strips 53 are in contact with the lnner surface o~
the member 51 and co~ered by the mas~io 52; ln Flg. 6~ tha
strips ~3 are embedded in the ~ree surfaoe o~ the mastic 52
while in Fig9 7~ they are totally enclosed within it. Fi~o
8~ is sim~lar to Fig~ 7~ except that the strips 53 are re-
placed by wire~ 5~.
It will ba apparent that the wires or other forms of
rein~oroement can be positlonad in any o~ the po~itio~9
~ .
10 shown ~n Figs~ 5 to 7. ::
Re~erring now to Fig~. 9 and 10~ there is shown a therm~
oplastic article 91 ha~i~g metal ribbon~ ~2 co-extruded
therewith. On ~xpansion~ an ar~icle as shown in Fig,. 10 is
produced~ the expansion o~ the portions of the thermoplastlc
material 91 bonded to ~he ribbon~ 92 during extrusion bei~g
inhiblted by thsir relatiYe immovabllity. .
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