Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C61/00—Shaping by liberation of internal stresses; Making preforms having internal stresses; Apparatus therefor
  • B29C61/06—Making preforms having internal stresses, e.g. plastic memory
  • B29C61/0608—Making preforms having internal stresses, e.g. plastic memory characterised by the configuration or structure of the preforms
  • B29C61/0625—Preforms comprising incorporated or associated heating means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
  • B29C65/3404—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint
  • B29C65/344—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint being a woven or non-woven fabric or being a mesh
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
  • B29C65/3404—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint
  • B29C65/3444—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint being a ribbon, band or strip
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
  • B29C65/3404—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint
  • B29C65/3444—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint being a ribbon, band or strip
  • B29C65/3452—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the type of heated elements which remain in the joint being a ribbon, band or strip forming a sleeve, e.g. a wrap-around sleeve
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/66—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by liberation of internal stresses, e.g. shrinking of one of the parts to be joined
  • B29C65/68—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by liberation of internal stresses, e.g. shrinking of one of the parts to be joined using auxiliary shrinkable elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
  • B29C66/51—Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
  • B29C66/52—Joining tubular articles, bars or profiled elements
  • B29C66/522—Joining tubular articles
  • B29C66/5221—Joining tubular articles for forming coaxial connections, i.e. the tubular articles to be joined forming a zero angle relative to each other
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
  • B29C66/51—Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
  • B29C66/52—Joining tubular articles, bars or profiled elements
  • B29C66/522—Joining tubular articles
  • B29C66/5229—Joining tubular articles involving the use of a socket
  • B29C66/52291—Joining tubular articles involving the use of a socket said socket comprising a stop
  • B29C66/52293—Joining tubular articles involving the use of a socket said socket comprising a stop said stop being external
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
  • B29C65/3472—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint
  • B29C65/3476—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" characterised by the composition of the heated elements which remain in the joint being metallic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
  • B29C66/71—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the composition of the plastics material of the parts to be joined

Definitions

• This invention relates to an assembly and to a method for passing an electrical current through a heat recoverable article.
• a heat-recoverable article is one whose dimensional configuration can be made to change substantially when subjected to heat treatment.
• a heat-recoverable article will usually recover towards an original shape from which it has previously been deformed but the term as used herein also includes articles which adopt a new configuration when subjected to heat treatment, even if it has not previously been deformed.
• Heat recoverable articles including those that comprise one or more members of a conductive polymer i.e. an organic polymer having sufficient finely divided electrically conductive material disposed therein to render it electrically conductive, are known. They may be used to provide sealing, insulating or protective coatings on substrates, for example, electrical joints and terminations. Reference may be made, for example to Pat Nos US 2,027,962, US 3,086,142, US 3,770,556, EP-0307207 and EP-0307205.
• Heat recoverable articles are typically recovered towards a; original configuration by means of a torch.
• it is also known (see British Pat. No. 1,265, 194, US Pat No. 4,421,582, EP Pat No. 0343757 and US Pat No. 4,570,055) to make heat recoverable articles out of conductive polymers and to cause recovery of the article by passing an electric current through the conductive polymer, thus raising the temperature of the article to the recovery temperature.
• Current may be supplied to the ends or intermediate points of the article by any suitable method. For example, alligator clips or other conventional clamps or electrodes may be used.
• One problem that may be encountered is maintaining contact with the heat recoverable article during recovery. For example for a tubular.
• an annular electrode applied over the outer surface of the article may lose contact with the shrinkable sleeve part way through the shrinking process so that shrinkage is halted prematurely.
• US 4,570,055 describes an assembly comprising a conductive tubular article and two electrodes which can change their size and shape to follow the recovery of the article, e.g. they may be spring electrodes to follow the radial heat shrinkage of the article.
• EP-A-0307206 Another method of overcoming the problem of the electrode losing contact with the heat recoverable article during recovery, is to arrange for that part of the article which is in contact with the electrode not to recover at all. even though other parts of the article do recover.
• EP-A-0307206 This describes a heat recoverable conductive polymeric tubular article in which electrodes are fixed to heat-stable support elements on the article, e.g. elongate flanges extending along the article. The flanges are not expanded or are only slightly expanded, so that they are not heat-recoverable.
• a first aspect of the invention provides an assembly comprising
• a second aspect of the invention provides a method of bonding to an elongate object such as a pipe or cable or a joint or splice therebetween using an assembly according to the first aspect of the invention, the method comprising
• the invention involves a heat recoverable element.
• a heat recoverable element By this it is meant that at least part, preferably all, the element is recoverable.
• recoverable is meant that the article will recover if heated to a sufficiently high temperature.
• the region of the element that is in contact with the electrodes may be heat recoverable (and typically is. for ease of manufacture), it is not actually recovered since the temperature of that region does not ever reach the recovery temperature.
• the tubular element is radially heat shrinkable, and the electrodes are positioned on the outer surface of the element.
• the region of the element in contact with the electrodes is the region underlying the electrodes and coterminous therewith.
• the electrodes, at least when positioned, are annular in shape. Therefore the region of the element in contact with the electrodes is the annular region immediately beneath the electrodes.
• the electrodes are positioned towards opposite ends of the tubular element so that the end regions of the element do not recover, and the intermediate region between the ends does recover.
• the wall thickness of the region of the element that is in contact with the electrode (hereinafter the "contact region") thicker than the wall thickness of the region of the element that is not in contact with the electrode (hereinafter the "non-contact region).
• the wall thickness in each of the contact region and the non-contact regions may or may not be uniform along the length or around their circumference of those regions.
• the wall thickness along most, preferably all, of the length of the contact region is greater than the wall thickness along most preferably all, of the length of the non-contact region, preferably 1.2, especially 1.4, more preferably 1.5,1.6, or even 2 times as great.
• At least one, preferably any cross-section through the region of the element that is in contact with at least one of the electrodes (the contact region) is larger than preferably 1.2, more preferably 1.4, especially preferably 1.5, 1.6 or even 2 times the area of at least one, preferably any, cross-section through the region of the element that is between the said at least two electrodes (the non-contact region).
• At least one of the electrodes is of sufficient thermal mass to act as a heat sink, thereby substantially preventing the said region of the element that is in immediate contact with the electrode being heated to a temperature sufficient to cause recovery of that region.
• the electrode comprises a metal.
• the electrodes may be provided on a backing sheet which can be wrapped around the outer surface of the element. This can optionally be removed after electrical current has been supplied to the element.
• the backing sheet must, of course, comprise a material which allows electrical current to pass from the electrode to the heat recoverable element.
• the region of the element that is in contact with the electrodes it does not mean that there has to be direct contact between the electrode and the element. What is meant is that region of the element which, if it did recover, would cause electrical contact between the electrode and the element to be broken.
• the embodiment within the invention, in which electrodes are provided on a backing sheet and positioned on the outer surface of a radially shrinkable element.
• the region of the element that is in contact with the electrode is the annular region immediately underlying the annular electrodes (and having an outer surface coterminous with the inner surface area of the annular electrodes) but separated therefrom by the backing sheet.
• the assembly according to the invention may be part of a larger tubular article, which has a heat recoverable element according to the invention at one or both ends. It may have a non-recoverable, or heat-stable section between the two end heat-recoverable elements.
• a larger article may be used for example to bond to pipes or cables or joints therebetween.
• the larger article is particularly suitable for covering a joint between district heating pipes.
• the heat recoverable element may be lined with a layer of material which can bond to an elongate object positioned within the heat recoverable element.
• the bonding material may be selected from materials which provide an adhesive bond and from, materials which provide a fusion bond. The selection will depend on the materials of the recoverable layer and on the object to which it is to bond.
• the bonding material will be heat-activatable, that is for example a material which can provide a fusion bond, or if a material which provides an adhesive bond (ie, an adhesive) a hot-melt adhesive or a heat-curable adhesive.
• EP-B-0245067 examples of materials that can be used as the bonding layer are described in EP-B-0245067 (B129).
• hot-melt adhesives which may be used as bonding material in the article of the invention are disclosed in US-4181775 and US- 4018733, which disclose formulations comprising polyamides modified with hydrocarbon waxes, and mixtures of acidic ethylene polymers and tackifiers.
• compositions based on ethylene vinyl-acetate copolymers, blended with hydrocarbon waxes and optionally butyl rubber are examples of materials that can be used as the bonding layer.
• a fusion bond (as the term is used herein) on the other hand is one that is based on physical interactions initiated by intimate contact between compatible materials in their visco-elastic state, and is more akin to a weld.
• Polymeric materials that may be used for a fusion bonding layer include, for example polyethylene, polypropylene, polybutene. copolymers of ethylene, propylene, butene and hexene. copolymers of ethylene with ethyl acrylate, vinyl acetate, acrylic acid, methacrylic acid, acrylic esters or methacrylic esters in which polyethylene predominates, blends of these polymers, and blends of these polymers with elastomers.
• the heat recoverable element of the invention comprises a conductive polymer, that is an organic polymer and, dispersed in the polymer, a particulate conductive filler.
• a conductive polymer that is an organic polymer and, dispersed in the polymer, a particulate conductive filler.
• Preferred materials are those described in EP-0307207 (RK365) and EP-0307205 (DK005) the disclosures of which are incorporated herein by reference. Typically such materials have resistivities at 25°C of less than 25 ohmcm.
• the diameter of the heat recoverable element may be in the range 90 mm to 560 mm, and the wall thickness in the range 3 mm to 10 mm, and the length in the range 250 mm to 750 mm
• the larger article may typically have a length in the region of 0.2 to 0.7 metres
• the remainder of the article may or may not also be heat recoverable. However if the electrodes are only positioned at either end of the said element(s) then electrical current will not flow through the remainder of the article so only the elemental will actually recover.
• Figure 3 shows the assembly of Figure 2 after the elements have been recovered onto an elongate object.
• FIGS. 4 and 5 show second assembly according to the invention respectively before and after the heat recoverable elements have been rendered heat recoverable
• Figure 6 shows the assembly of Figure 5, with electrodes installed
• Figure 7 shows the assembly of Figure 6 after the heat recoverable elements have been recovered onto an elongate object.
• Figure 1 shows a tubular article comprising end regions 2, a central region 4, and intermediate tapering regions 5, the end regions 2 being of smaller cross-sectional area than the intermediate region 4.
• the article has an increased wall thickness, that is an increased cross sectional area at either end of the end regions 2. This is illustrated by reference number 6 in the drawings.
• the material of the entire article comprises a conductive polymer material.
• the article of Figure 1 is made by moulding.
• Figure 2 shows the article of Figure 1 after the end regions 2 (now designated 2') have been expanded (now referenced 2'). This makes them heat recoverable, in particular radially heat shrinkable.
• the presence of tapered section 5 in the moulded part facilitates the expansion process.
• the end regions are heat recoverable.
• the increased wall thickness of regions 6 is not significantly affected by the expansion, although, of course, their internal diameter is increased by the expansion.
• Silver paint electrodes 10 are shown painted on the regions 6.
• An electrical power supply may be connected by e.g. alligator clips to the electrodes 10 and electrical current supplied sufficient to heat the end regions 2 to effect heat recovery.
• FIG. 3 shows the article after recovery onto an elongate pipe 12. It will be seen that regions 6 have not recovered. Hence there is no risk of loss of contact between the electrode 10 and the conductive polymer region 6 below. The region between the electrodes 10 has recovered into contact with the pipe (now indicated as 2").
• Figure 4 shows another tubular article according to the invention. It has end sections 22, a central section 24 and tapering sections 25, the end section 22 being of smaller cross-sectional area than central section 24. In this case there is no area of increased wall thickness corresponding to region 6 in the article of Figures 1 to 3.
• the article comprises a conductive polymer material, and is made by moulding.
• Figure 5 shows the article of Figure 4 after end regions 22 have expanded to render them radially heat shrinkable (now indicated as 22'). Tapered regions 25 facilitate expansion.
• Figure 6 shows two pairs of metal braid electrodes 26 provided on backing sheets 28 which are wrapped around respective end sections 22' of the article of Figure 5.
• the sheet 28 allows electrical current to flow from the electrode 26 to the conductive polymer region 30 immediately beneath it.
• the metal electrodes 26 have a sufficient heat mass to act as a heat sink to prevent recovery of the conductive polymer region immediately beneath them.
• the article is positioned around pipe 32, but not yet recovered.
• Electrodes 26 are then connected to an electrical power source and powered to effect recovery in a manner similar to that described for Figures 1 to 3.
• Figure 7 show the assembly of Figures 4 and 5 after recovery onto a pipe 32, and after removal of the electrodes 28 and backing sheet 28.
• a lining of fusion bondable material of the type described hereinbefore is included, lining the end regions 2 and 22. This is not shown in the drawings for simplicity. It is activated by the heat which effects recovery. It enhances or forms the bond to the pipes 12, 32.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Textile Engineering (AREA)
• Lining Or Joining Of Plastics Or The Like (AREA)
• Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
• Cable Accessories (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10703418

Family Applications (1)

Country Status (4)

Cited By (8)

Citations (6)

• 1991
  • 1991-10-23 GB GB919122511A patent/GB9122511D0/en active Pending
• 1992
  • 1992-10-22 WO PCT/GB1992/001938 patent/WO1993008013A1/en not_active Application Discontinuation
  • 1992-10-22 EP EP92921589A patent/EP0609302A1/en not_active Ceased
• 1994
  • 1994-04-22 FI FI941881A patent/FI941881A0/fi not_active Application Discontinuation

Patent Citations (6)

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