CA1159377A - Recoverable sleeve assembly - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A recoverable sleeve assembly is disclosed having an inner elastomeric tube and an outer rigid tube surrounding and secured to the inner tube holding the inner tube in outwardly stretched condition and wherein the outer tube extends axially beyond and covering at least one end of the inner tube and secured to that end of the inner tube. The end of the outer tube extending beyond the end of the inner tube has a thickness equal to the total thickness of the inner tube plus the thickness of that portion of the outer tube that surrounds the inner tube. The outer tube is a rigid thermosetting adhesive polyurethane comprising a polyester polyol reacted with an isocyanate whereby the outer tube is sufficiently adhesive to hold the inner tube in outwardly stretched condition but will peel from the inner tube upon impact or force or application of heat without need for a solvent. The polyester polyol is disclosed as trimethylol propane branched glycol adipate polyol or polycaprolactone polyol modified with 1,4 butanediol reacted with the isocyanate. The sleeve is applied around a substrate, and the outer tube is fractured by impact of force to allow the inner tube to shrink and the fragments of the outer tube to peel from the inner tube.

Description

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3 RECOVERA~LE SLEEVE ASSEMB~Y
4 The present invention is directed to a recoverable sleeve assembly that can be applied without heat or a solvent. ~eat 6 shrinkable sleeves with or without internally coated sealant 7 have found wide utility for insulating conductors in a splice.
8 1 A major disadvantaye is the necessity of a heat source to 9 ¦accomplish th~ ~Gcovery. The heat source may be an open flame 10 ¦ or hot air gun, both of which provide a hazard in an atmosphere 11 ¦ where combustible gas may exist such as in a coal mine or man-12 1 hole.
13 U. S. Patent 4,035,534, to Nyberg discloses a heat 14 1 shrinkable member formed around and held by adhesive or 15 ¦ coupling agent to an elastomeric material. ~he heat shrinkable 16¦ member is disclosed as a heat recoverable thermoplastic material ~71 having sufficient rigidity at storage temperatures to hold the 18¦ elastomeric material in the desired stretched position. U. S.

~91 Patent 3,243,2ll to Wetmore discloses a sleeve ass~mbly co~- _ 201 prising a rigid fusible tubular member surrounding a recoverable 21 tubular member and holding the recoverable member in expanded 221 condition under tension. The fusable me~nber is describcd as 231 ~irtually any material capable of being rendered flowable by 24 the application of heat such as thermoplastic materials as well as thermosetting materials.
26 ~ number of methods Eor recovering an elastomeric sleeve 27 without the usq of heat have been proposed and some of these 28 are in a~tual use. ArtlcleF3 and methodc; emyloying both .
29 in~ernal support mombers and cxternal support members have be~!n designed~ Methods with internal support members are discloscd 31 in U. S. ratonts 2,725~62l ~o G~tes alld 3,515~798 to Sievert.
32 Thc Gates patent discloscs the use o a sloove o~ Era~yiblc ., ~

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1 ¦material holding an elastic sleeve or tube in stretched

2 ¦ condition so that an impact to the assembly disintergrates

3 ~ the inner sleeve allowing the elastomeric portion to collapse

4 1 and shrink. The Sievert patent discloses an elastic cove~

5 ¦ with an internal support core which can be removed by spirally

6 1 unwinding; such an article is in wide spread use. Internal

7 ~ support techniques have two major aisadvantages. No sealant

8 1 or adhesive can be applied to the inner surface to aid in 91 bonding the shrinkable member to a substrate such as a cable, -and the internal support is often difficult to remove over 111 an irregular substrate.
12¦ Several shrinkable elastomeric tubes have been designed 13¦ with external support means. U. S. Patents 3,770,876 to ' 14¦ Post discloses external means provided to pre-stretch the 15¦ elastomeric tube at the time of installation. U. S. Patent 16 3,824,331 to Mixon et Rl discloses an elastic tubular member 17¦ rolled back on itself in storage condition on an external ; 18 support member and unrolled at the time of use. This con-19¦ struction restricts the elastic member to a thin wall rubber _20 ¦ sleeve thus reducing the abrasive resistance of the resultant 21¦ cover. U. S. Patent 4,070,746 to Evans et al discloses an 22¦ external rigid restraint bonded to the outer surface of an 23 ¦ elastomeric member with the bond susceptible to attack by 241 solvents to allow the elastomeric sleeve to peel away from 2s1 the outer member upon the application of the solvent. British 26¦ Patent 1,556,677 discloses a recoverable article includinq 271 the ~eature~ o~ the Evans et al patent hut also disclosing 231 provislon ~or an outer restraining member capable o~ beinq .
291 sQgmented or broken by shattering, R typical restrainlng 301 mean~ is disclosed a~ a thqLmoplastic such a~ polyvinyl 3~1 chloride, U. S, Patent 4,l79,320 to Midgley disaloses a re-32 Govcrabla ar~icle having an elastomeric mamber hqld ln ', . . .

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37'7 s-tretched condi-tion by a flexible ou-ter reS-traininCJ
means provicled with score lines.
The presen-t invention resides in a recoverable sleeve assembly includingan inner elas-tome,ric tube and an ou-ter rigid tube surrounding and secured to the inner tube and ho"Lding -the inner tube in outwardly stretched condition.
The outer tube extends axially beyond and covers at least one end of the inner tube and is secured to the end of the inner tube.
A specific embodiment of the invention provides a recoverable sleeve assembly wherein an inner elastomeric tube is held in expanded condition by a rigid thermose-tting polyuret'hane outer tube which is secured to a pre-stretched elastomeric inner tube. The recoverable sleeve assembly combines the two essen-tial features of rigidity and optimum peel strength in a single unit. The outer supporting tube can be removed at the time of recovery without the use of any solvent to break the adhesive bond. The outer tube is a rigid thermose-ttiny polyure-thane adhesive made from a polyol reacted with an isocyanate in a formula-tion to provide a decJree of adhesion which has suEEicient adhesive strenyth in tension to hold -the inner tube stre-kched but is weak enouyh in peel to allow the riyid sleeve to be r~moved after breakiny by impact or application of hea-t without the use of a solven-t.
The preEerred thermose-tting adhesive is a po:lyes-ter po:lyo:l Eormed Erom a m1xture oE tr:imethy:Lol propane brancilecl glycol, ad:ip~-te polyo:L or polycaprolac-tone polyol mocliEied , . , s ~ /

33~7 with 1,4 butanediol reacted with the isocyana-te.
In a specific embodimen-t -the outer -tube has a thickness equal to the to-tal thickness of the inner tube plus the -thickness of that portion of -the outer tube which surrounds the inner tube and preferably the outer tube extends axially beyond and covers and is secured to both ends of the inner tube.
Other features and advantages of the present invention will become more apparent upon perusal of the following specification taken in conjunction with the accompanying drawings wherein similar characters o~
reference refer to similar elements in each oE the several views.

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. , 3 Figure 1 is a perspective view partially broken away of 4 one recoverable sleeve in accordance with the present inventio~O
Figure 2 is a elevational view, partially in section, 6 of a portion of the structure shown in Figure 1 taken along 7 line 2-~ in the direction of the arrows.
8 Figure 3 is a elevational sectional view of a recoverable sleeve asser~ly in accordance with the present invention for insertion over a substrate.
11 Figure 4 is an enlarged sectional view of that portion of 12 the structure shown in Figure 3 deiineated by the line 4-4, 13 Figures 5, 6 and 7 illustrate one manner in which the 1 xecoverable sleeve is utilized in practice.
1 Figures 8 and 9, 10 and 11, and 12 and 13 illustrate other 16 manners of use of the present invention.
17 Figure 14 is a side elevational view, partially in section, 18 schematically illustrating certain of the steps in forming 19 a recoverable sleeve in accordance with the present invention. _ Figure lS is an elevational sectional view of a molding 21 step utilized in forming the recoverable sleeve assembly in 22 accordance with the present invention.
23 Figure 16 illustrates a recoverable sleeve assembly formed 24 in accordance with the molding step illustrated in Figure 15.
Fiyures 17 and 18 are flgures similar to Figures 15 and 26 16 illustrated in another embodiment of the present invention.

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DESCRIPTION OF PRFFERR~D EMBODIMENT
2 Referring now to the drawing with pa~ticular reference to 3 Pigures 1 - 3, there is illustrated a preferred embodiment of 4 the recoverable sleeve assembly in accordance with the present invention. The sleeve assembly 10 includes an inner elastomeri~
6 tube 11 in outwardly stretched condition and an outer rigid 7 tube member 12 surrounding and secured to the inner tube 11 and 8 holding the inner tube in its out~ardly stretched condition.

9 The outer tube 12 includes a central portion 1~ surrounding and secured to the outer surface of the inner tube 10 and two end 11 portions 14 and 15 extending axially beyond the ends lla and llb 12 o~ the inner tube and secured to the ends lla and llb of the 13 inner tube. The end portion~ 14 and 15 have a thickness equal 14 to the total thic~ness of the inner tube plus the thickness of the central portion 13 of the outer tube which surrounds the 16 inner tube 11.
17 The end portions 14 and 15 serve several different purposes.
18 They provide a strong support ring at the end of the assembly 19 which is thicker and stronger in the radial direction than the _ 20 central portion 13 of the outer tube. They cover and are secured 21 to the end of the inner tube 11 preventing access to the inter-22 face between the outside surface of the tubular member 11 and the 23 central portion 13 of the outer me~ber where peeling ,apart 24 of the inner and outer tubular members 11 and 12 begins.
25 Additionally they serve to shield the intarace between the 26 inner and outer tubular member~ 11 and 12 at the end of the 27 tubular member 11 from engagement by the end of a substrate 16 2a such as a c~ble onto which the recoverablc sleeve i~ tele~copi- .
2 cally moved SUCII as for coverincJ a splJca or the like, Contao~
3 between the ~ubstrate 16 and either the interPace or tho end ~f 3 tha innor t:ube 11 can causo the tubes 11 and 12 to becJirl to 3 pcel apart~ --., . . . ~5_ . .. . . .. . .. . . . ..... ... ~ ... . .. . . . ..
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. .. :, ~ ., '' ^.~.'il 59J77 1 ¦ The inner tubular member is preferably a rubber elastomerie 2 ¦sleeve. The major property requirement of the elastomerie 3 ¦sleeve or tube 11 is that it must have low permanent set when 4 ¦stretched such as approximately 100 to 150% radially. This i3 ¦required since in the end produet the elastomeric tube 11 will 6 ¦be held in expanded condition for extended period of time during 7 Istorage. A preferred material for the inner tube 11 is a 8 ¦neoprene rubber formulation which has necessary recovery - _ .
9 ¦properties with flame retardance, particularly suitable for

10¦ splicing coal mining cable. Typical mechanical properties ~or

11 ¦this formulation are tensile strength of 1800 psi, elongation

12 ¦of 400~ and 100% modulus of 430 p~i.

13 ¦ The preferred outer tube 12 is a rigid thermosetting

14¦ adhesive comprising a polyurethane formed of a mixture of a polyol

15 ¦preferably polyester polyol such as TMP (trimethylol propane)

16 ¦bra~ched glycol adipate or polycaprolactone polyol modified with 1

17 ¦4 butanedi~l reacted with an isocyanate. The trimethylol propane

18 ¦branched glycol adipate preferred is a hydroxyl terrninated

19 ¦polyester in the lecular weight range of 1000-2000 which _

20 can be prepared from dibasic acids such as adipic and se~aeie

21 reacted with an excess glycol (ethyleneglycol or diethylene

22¦ glycol) or polyhydric alcohol such as glycerol or trimethylol

23 ¦ propane. Reaction with a slight excess of glycol insures that

24 ¦ the polyester will be hydroxyl terminated. These hydroxyl

25 ¦ groups are available to participate in the urethane reaction.

26 ¦ A pxeferr~d formulation is as ~ollows:

27 ¦ FO~ULATION I

28 Parts I ~r---P branch~d,~lycol adipate~FORMREZ 102, .

29 I Wi~co Che~nieal) 15 1~ 4 b~tanediol ~BASF)

30 ¦ 3 Phenylrnercurie propionate aatalyst I ~ T~SOI. 57, ~erck) 81 1 antio~idant ~ c~ol ll Monsanto) 32 ¦ 1 releas~ ~In~ -20~ Axel Pl~5tlcs) ..................... .........', .

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1 101 parts of the above ~olyester polyol were reacted with 2 ¦115 parts of a polymeric ~socyanate such as Rubinate-M by 3 ¦Rubicon Cl-emicals to produce a composition having a tensile 4 ¦modulus of 363,000 psi. Other isocyanates such as PAPI 135 by 5 ¦ ~pjohn and MONDVR MR by Mobay Chemicals can be used.
6 ¦ The polymeric isocyanatPs or diisocyanates when reacted 7¦ with the polyol in the presence of a catalyst react rapidly to 8¦ form a polyurethane. The ratio of the isocyanat:e to the polyol 9¦ mixture should be in the range of 1.05 to 1.10 equivants of 10¦ isocyanate per eguivalent ~eight of polyol. A unique feature 111 f the polyurethanes used in this invention is that they can be 12¦ mixed in a high intensity mixing head and injected into a mold 13¦ while still liquid and within a few minutes cure to a solid 14¦ thermoset resin.
15 ¦ Other formulations can be based on polycaprolactone polyols 16 ¦ modified with l, 4 butanediol and reacted with an isocyanate.
17 The exact modulus of the outer shell is difficult to define since 18 ~he ability to hold the rubber sleeve expanded without collapsing 19 is a function both of the modulus and the thickness of the outer _ shell. For example, both of the following polyol formulations 21 reacted with isocyanate (PAPI 135 by Vpjohn), will function in 22 this invention.
23 . FO~UI.ATION II
Parts 24 65 polycaprolactone polyol (NIAX polyol PCP 0300, Vnion Carbide) 20 polycaprolactone polyol ~NIAX polyol PCP 0200, Union Carbide) 26 15 l/ 4 butanediol (BASF) 27 100 parts of the above polyol were reacted with 100 parts 23 of PAPI 135 to produce a composition having a tcnsile modulus o~ 210,000 p~i.
29 FORMU~CO~ III
Part~
~~~~lycaprvlactone polyol ~ X pol,yol PCP 0300, Vnion Carbidc)

31 15 1~ 4 butanediol ~ASF)

32 100 parts o~ thls ~ormul.ltion reactod with llS part:s o~ PAPI
~ 135 p~oduc ~ ~ompo:~tlon h~vlng a tonsll~ mo~l~luo of 317~00d P~

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b~1593'~7 ( 1 Obviously For~nulation III can be used in a thinner cross- ~:
2 section to resist the collapsing force of an expanded rubber 3 tube. Howe~er, all forrnulations are effective.
4 In the present invention a thickness of 0.040-0.130 inch is preferred for the ou~er mernber for an unexpanded neoprene 6 rubber inner tube .140 inches thick and ID of .85 inches which 7 is then stretched to an ID of 1.85 inches.

8 Other polyols which may be substituted for the polyols in 9 the above forrnulations to produce the rigid outec tube of the sleeve assernbly are-polyester polyols such as ~ y~1 11 p~v~e-g~yeo-~ a~*e~-and poly neopentyl adipate and polyether ~, 12 polyols such as polyethylene glycol, polypropylene glycol, 13 alithatic hydroxy terrninated polyester and polypropylene 14 derivitives of propylene glycol, trimethylolpropane ~r sucrose.
A typical application of the recoverable sleeve assembly lb 10 is illustrated in Figures 5, 6 and 7. ~he recoverable 17 sleeve assernbly 10 is placed on the substrate 16 and rested on 18 a flat surface. By stamping on the recoverable sleeve assembly 19 10 and allowing the assernbly to set for 30 second the inner 20 tube 11 will break free of the fragrnents of the outer tube 12 _ 21 and shrink around the substrate 16. The outer shell fragments 22 are peeled away. Flexing of the splice as illustrated in 23 E'igure 1~ will help to remove the fragrnents of the outer tube 24 in any area where the inner tube has not been cornpletely released~
26 Other techniques of utili2ation are illustrate~ in Figures 27 8 - 13. In Figures 8 and 9 utilization of the recoverable 23 sleevq assarnbly 10 is illustratcd by fir-;t fractur;ng such as .

29 ~7ith ha~MneL Il at only one erl~l of the assemhly 10 whereby the ~ inner tube 11 begins to peel aw~ly from the o-lter tmbe 12 and 3l then peels away successively longitudina]ly of the two members.
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1 ¦The remainder of the outer tube 12' can then be removed by 2 ¦frac~uring at the location or elsewhere after movement 3 ¦longitudinally o$ the substrate 16.
4¦ The present invention can be utilized without heat, but ¦ Figures 10 and 11 illustrate that heat can be applied to the 6 ¦ assembly 10 adjacent the joinder of the end of the inner tube 7 ¦ 11 to the end portions of the outer tube 12. The bond between 8 1 the inner tube 11 and outer tube 12 will be weakened and the :
9¦ end of the inner tube 11 will release and shrink peeling away 10¦ successively longitudinally from the outer tube 12. The outer ; 11¦ tube 12 can then be r~moved such as in the manner described 12¦ with reference to Figures 8 and 9 13¦ Figures 12 and 13 illustrate an alternative embodiment of 14 the present invention wherein the outer tube 12 " extends .
15 ¦ axially beyond and covers only one end of the inner tube 11.
16 ¦ In this embodiment when the substrate 16 is inserted into the - 17 ¦ assembly through the end.where the outer tube projects beyond 18 ¦ the inner tube, the extending end portion of the outer ~ube 12'' ; 19¦ protects engagement of the substrate with the end of the inner _ 20 ¦ tube that could cause the inner tube to begin to peel away from 21 ¦ the outer tube.
.~ 22 ¦ The polyurethane shell can be molded in a relatively short 23¦ cycle. Referring now to Figures 14 - 16 t`here is illustrated 2~1 ~ preferred molding operation. In Figure 14 the .inner tube 25 ¦ 21 in unexpanded condition is providad over the outside of a 26 ¦ first, hollow cylinclrical, small diameter mandrel 22 one end of 27¦ which is connected to an air supply and the other end of which 28¦ is fittad into the small diameter end of a tapered mandrel 23.
29 ¦~'apered m~ndrel.23 is pr~vided with a aentral bore 24 which .
30 ¦communicatcs with ~.ha cen~ral hore 25 o~ mandrel 22. Passageways . ..
31 ¦2G axtend from tha taperad mandrel central bore 2~ to th~ 1.

32 ¦~ ~

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~ 93'~7 fi 1 outside surface thereof terminating in ports 270 The large 2 ¦diameter end of the mandrel 23 fits on a small diameter 3 ¦cylindical end extension 31 of a matching larg~ diameter 4 ¦mandrel 32. The other end of the large diameter mandrel 32 is provided with a similar cylindrical end extension 33 which 6 ¦isconnected to an airsource for passing air through a central 7I axial bore 34 and radial passages 35 to ports 36 in the 8 ¦exterior surface of the mandrel 32. The elastomeric tube 21 . . . .
9¦ is slid longitudinally from the small mandrel 22 over the _-10 ¦ tapered mandrel 23 onto the outside surface of large diameter 11¦ mandrel 32 whose diameter is equal to the desired expanded I ~
12¦ diameter o the inner tube 11 of the recoverable sleeve assembly.
13 ¦ Mandrel 32 is disconnected from the air supply and from 14 tapered mandrel 23 and with the stretched rubber sleeve 21' .
15 ¦ acts as the central core in a mold.i}lustrated in Figure 15.
16 ¦ The mold consists of lower and upper halves 41 and 42 each of 17 ¦ which have semi-cylindrical cavities which when the parts are 13 ¦ assembled provide a hollo~ cylindrical cavity having a diameter 19 ¦ equal to the desired out side diameter of the outer tube 12 of 20 ¦ the assembly. The mold halves 41 and 42 contain semi-cylindrical _ 21 recesses ~or receiving the small diamater cylindrical and 22 ¦ extensions 31 and 33 of the mandre.l 32. The mandrel ~2 with 23 ¦ the attached elastomeric tube 21' is placed in the lower hal~
24 41 of the mold and the mold closed and the above mentioned 25 ¦ polyol~isocyanate mixture injected .into the mold around the 26 ¦ central core. The clearance between the outside surface of 27 ¦ the elastomeric tube ,21' of the central core and ths mold 23 ~avi~y is the wall ~:hickness o~ the outer tube 12 that surrounds .
29 ¦ thq inn~r tubq 11. It ls noted that the cavity ~3 Oe tllq 30 ¦ mold 1~ th~ full length o~ the mandr~l 32 ~hereas thq expandqd 31 elastomeric s].eevs is of lesser length and spaced :erom the ends 32 / .

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1 ¦of the cavity 43. The material forming the outer tube will fill 2 ¦the space between the e~ds of the expanded tube 21 and the 3 ¦qnds of the mold cavity 43. The mold is heated to accelerata 4¦ the cure of the urethane. After about 10 to 15 minutes the 5¦ mold i5 opened and the core removed. After post-cure, the 6¦ composite rubber sleeve and polyurethane outer shell are blown 7 ~ off the rnandrel 32 by prsssuring the inside of the mandrel.
8 ¦ Prior ~o insertion of the mandrel 23 and expanded tube 9 21' into the mold, the outer surface of the sleeve 21' is 10¦ cleaned with a suitable solvent and treated with a release 11¦ agent to control the degree of adhesion of the outer urethane 12¦ jacket. Release agent~ such as zinc sterate, fluorocarbon basPd ~*~
13 releases or silicones such as RAM 225 by Ram Chemicals are 14 ¦suitable.
While the preferred recoverable sleeve asse~bly in 16 ¦ accordance with the present invention includes end portions of 17 ¦the outer member extending beyond both ends of the inner member, 18 an end extension of the outer ~ember can be provided on only 19 ¦one end of the inner member or on neither of the ends. _ 20 ¦ Figs. 17 and 18 illustrate the molding method for providing 21 ¦ an assembly with an outer member extension on only one end.
22 ¦ As illustrated there the expanded tubular member 21'' is 23 ¦ positioned on thq mandr~l 23 with one end of the tubular member 24 all the way at the end of the larger diameter portion of the 25 mandrel 32 leavlng space between the opposite end of the tubular 26 member 21~' and the end of the hollow cavity 43 of the mold.
27 When the urethane mi~ture is injected into the mold cavity an 28 end yortion oP the outer rnember will project beyond only one 29 Qnd oP ~he inno~r mqmbcr. ~1hen the 40re m~mber ls removed from 3~ thq rnold~ ~he r~40ver~ble sleevq as~Qmbly r~moved Prom the 31 mandr~l will app~ar as in ~iCJure 18.

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Claims (11)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a recoverable sleeve assembly including an inner elastomeric tube and an outer rigid tube surrounding and secured to the inner tube and holding the inner tube in outwardly stretched condition, the improvement comprising the outer tube extending axially beyond and covering at least one end of the inner -tube and secured to said end of the inner tube.

2. In the sleeve assembly of claim 1 -the portion of the outer tube extending beyond said end of the inner tube having a thickness equal to the total thickness of the inner tube plus the thickness of that portion of the outer tube which surrounds the inner tube.

3. In the sleeve assembly of claims 1 or 2 the outer tube extending axially beyond and covering both ends of the inner tube and secured to said ends of -the inner tube.

4. In a recoverable sleeve assembly including an inner elastomeric tube and an outer rigid tube surrounding and secured to the inner tube and holding the inner tube in outwardly stretched condition, the improvement comprising:
an outer tube extending axially beyond and covering at least one end of the inner tube and secured to said one end of the inner tube and, comprising a rigid thermosetting adhesive polyurethane comprising a polyol reacted with an isocyanate whereby the outer tube is sufficiently adhesive to hold the inner tube in outwardly stretched condition but will peel from the inner tube after breaking by impact or application of heat without use of a solvent.

5. In a sleeve assembly of claim 4 the outer tube formed from a trimethylol propane branched glycol adipate polyol modified with 1, 4 butanediol reacted with said isocyanate.

6. In a sleeve assembly of claim 4 the outer tube formed from a mixture of polycaprolactone polyol modified with 1,4 butanediol reacted with said isocyanate.

7. In a sleeve assembly of claim 4 the portion of the outer tube extending beyond the end of the inner tube having a thickness equal to the total thickness of the inner tube plus the thickness of that portion of the outer tube which surrounds the inner tube.

8. In the sleeve assembly of claims 4 or 7 the outer tube extending axially beyond and covering both ends of the inner tube and secured to said ends of the inner tube.

9. In a sleeve assembly of claims 5 or 6 the ratio of the isocyanate to the polyol mixture being in the range of 1.05 to 1.10 equivants of isocyanate per equivalent weight of polyol.

10. In a recoverable sleeve assembly including an inner elastomeric tube and an outer rigid tube surrounding and secured to the inner tube and holding the inner tube in outwardly stretched position, the improvement comprising:
a outer tube extending axially beyond and covering at least one end of the inner tube and secured to said one end of the inner tube and, comprising a rigid thermosetting adhesive polyurethane comprising substantially 101 parts of a mixture of trimethylol propane branched glycol adipate, 1,4 butanediol,catalyst, antioxidant release agent and substantially 115 parts of a polymeric isocyanate.

11. In a recoverable sleeve assembly including an inner elastomeric tube and an outer rigid tube surrounding and secured to the inner tube and holding the inner tube in outwardly stretched position, the improvement extending axially beyond and covering at least one end of the inner tube and secured to said one end of the inner tube and, comprising:
an outer tube comprising a rigid thermosetting adhesive polyurethene comprising substantially 100 parts of a mixture of polycaprolactone polyol and 1,4 butanediol and substantially 100-115 parts polymeric isocyanate.