EP0081248A1 - Geschäumte Petrolatum-Kabelfüllmasse - Google Patents

Geschäumte Petrolatum-Kabelfüllmasse Download PDF

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Publication number
EP0081248A1
EP0081248A1 EP82200424A EP82200424A EP0081248A1 EP 0081248 A1 EP0081248 A1 EP 0081248A1 EP 82200424 A EP82200424 A EP 82200424A EP 82200424 A EP82200424 A EP 82200424A EP 0081248 A1 EP0081248 A1 EP 0081248A1
Authority
EP
European Patent Office
Prior art keywords
petrolatum
cable
filler
wax
weight
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP82200424A
Other languages
English (en)
French (fr)
Inventor
Johannis Doorn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Witco Corp
Original Assignee
Witco Chemical Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Witco Chemical Corp filed Critical Witco Chemical Corp
Publication of EP0081248A1 publication Critical patent/EP0081248A1/de
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
    • H01B7/282—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
    • H01B7/285—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable
    • H01B7/2855—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable using foamed plastic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/17—Protection against damage caused by external factors, e.g. sheaths or armouring
    • H01B7/28—Protection against damage caused by moisture, corrosion, chemical attack or weather
    • H01B7/282—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable
    • H01B7/285—Preventing penetration of fluid, e.g. water or humidity, into conductor or cable by completely or partially filling interstices in the cable

Definitions

  • This invention relates to telecommunication cables of the kind comprising a multiplicity of plastic-insulated conductors enclosed within a water-proof sheath. More specifically this invention relates to a filler to be contained between the conductors and within the interstices of the material of the external sheath.
  • An electrical or communications cable is comprised of a great number of pairs of single conductive wires. Each of these singles is coated with a dielectric material to insulate them individually from one another. A large number of these singles are then collected into a bundle which is the cable. The cable is coated on the outside within a sheath of a dielectric material to make an integral structure.
  • Austrian Patent No. 330,871 discloses gross additions of air at the time of filling the cable with silica jelling agents and oil.
  • liquified gases such as freon., butane and pentane
  • an acceptable cable filler which utilizes substantially all petrolatum or petroleum jelly foamed with high volumes of a gas, such as air, in a closed-cell, stabile, pre-foamed condition.
  • the cable filler of present invention is a foamed petrolatum having a high hydrocarbon oil content with fine wax particulates dispersed throughout, and which is formed as a gas-filled, closed-cell foam having a cell volume of from 35 to 55%.
  • the gas is preferably air.
  • high oil contents of 40% to 90% by weight were useful in forming .the foam, and yet the foam remained stabile.
  • the petrolatum formed of hydrocarbon oil and wax is heated to 50°C to 95°C and preferably 80°-90°C to achieve a 40:60 to 90:10, oil to wax ratio, and then a substantial volume of air under extreme agitation and shear action is pumped through the oil and wax to comminute the wax to fine particulates of less than 100 microns. This is believed to help provide a structural integrity to the foam.
  • Petrolatum or “petroleum jelly” as used hereinbefore and hereinafter shall be construed as being synonymous with and include hydrocarbons of the methane and olefin series of C 16 u p to about C 6S .
  • Petrolatums by definition usually contain about 10% by weight of oil.
  • Petrolatums useful in the present invention contain surprisingly much higher percentages of about 40% to 90% by weight of oil at about 50°-95°C, as more fully discussed hereinafter.
  • the petrolatum preferably has a molecular weight range of 600 to 700.
  • the present.invention comprises a cable with a cable filler which comprises a pre-foamed petrolatum or petroleum jelly in which fine wax particulates are dispersed in a high liquid oil portion of the petrolatum.
  • a petrolatum of high oil content is heated to 50°C to 95°C, and preferably about 80°C-90°C, to where the liquid oil-to-solid wax ratio is at least about 90:10.
  • a high volume of 35% to 55% by volume of air is blown into the petrolatum under extreme agitation. It was surprisingly found that this combination of high air volumes with high agitation providing shear forces and high liquid-to-solid ratio created very fine particulates (less than 100 microns) of the solid wax, which particulates were evenly dispersed in the liquid portion of a micro-void (less than 100 micron-voids), closed-cell foam structure.
  • the high shear forces reduce the wax particulates from up to about 1,000 microns to where substantially all the particulates are less than 100 microns, and preferably less than 5 to 10 microns.
  • the solid wax particulate portion of the petrolatum is generally formed of a mixture of paraffinic and microcystalline waxes. The microcystalline waxes were found to most advantageously form fine particulates.
  • petrolatum structural viscosity at foaming Another important aspect of the present invention is the petrolatum structural viscosity at foaming. It has been found that petrolatums having oil contents of about 40% - 90% by weight, should exhibit a viscosity in the range of 50 to 10,000 centistokes at about 60°-80°C.
  • the foam once formed is then pumped into the cable core and flows in the interstices of the cable strands or conductors. Upon cooling in the cable, the foam is further solidified, and found particularly useful in underground cables with operating temperatures of -10°C to +20°C, and also found to be useful even when subjected to temperatures up to 80°C.
  • a petrolatum when pre-foamed according to the present invention provides an exceptional cable filler material.
  • the pre-foamed petrolatum of the present invention exhibits excellent properties'and characteristics particularly, low density, good dielectric, low cost, good stability, and improved flexibility in a cable.
  • the relatively small quantity of very fine wax particulates dispersed in oil permits a-lattice- type network to be formed when air or an inert gas is blown in large quantities through the petrolatum.
  • the particulates are finely dispersed through the lattice closed-cell foam structure.
  • inert gas as used hereinbefore and hereinafter throughout the specification and claims, it is contemplated to include air and the inert gas series (e.g., argon, neon, xenon, and the like) as well as organic gases which do not react with the petrolatum and will not condense at the normal operating temperatures of the cable (e.g., methane, ethane and propane), but excludes the higher molecular weight hydrocarbon gases such as pentane and butane; the latter being in common use in prior art foams. Furthermore, with the lighter inert gases, the bulk weight of the filler is substantially reduced with a concommitant reduction in savings in cable costs.
  • inert gas series e.g., argon, neon, xenon, and the like
  • organic gases which do not react with the petrolatum and will not condense at the normal operating temperatures of the cable (e.g., methane, ethane and propane), but excludes the higher molecular weight hydrocarbon gases such as
  • Cable 1 comprises an outer sheath 2 containing a plurality of individual conductors 3; each of said conductors 3 comprises a wire 6 being covered with an insulator 5.
  • the foamed petrolatum filler 4-of this present invention fills the interstices between the several conductors 3.
  • a metal core wrap 7, which is impervious to the petrolatum retains the conductors 3 and filler 4 in a fixed manner.
  • the filler 4 is shown with a plurality of closed-celled voids 8, although in actuality the voids may be microscopic in nature, and therefore not necessarily visible to the naked eye.
  • hydrocarbon polymeric material of a molecular weight of at least that within the wax range may be added to the petrolatum.
  • the molecular weight (m.w.) of the polymeric stabilizer may be from 2,000 to 200,000 and preferably 5,000 to 100,000. Other high molecular weight stabilizers are also within the contemplation of the invention.
  • One preferred stabilizer is a polyisobutylene-wax mixture of normal slack wax as obtained from medium neutral oil or bright stock oil, and a polyisobutylene in a m.w. range of 100,000 to 200,000, and up 1,000,000.
  • the polymeric stabilizer should only present in amounts of from about 0.01 to 0.5 weight percent based on the weight of the unfoamed petrolatum, and preferably 0.02 to 0.2 weight percent.
  • a second operating run at the same machine setting produced a foam with cupweights of 110 to 120 grams.
  • a petrolatum as in Example I was formed in a Oates Foaming Machine having the following settings:
  • the foam cupweight was 119 grams per 200 ml. cup (sp.gr. 0.6).
  • the foam had a microscopic closed-cell structure.
  • a petrolatum as in Table I having a melting point less than that of Examples I and II was foamed in the machine having the following settings:
  • the foam cupweight was relatively high at 150-165 gm/200 ml. the foam had a microscopic closed-cell structure.
  • Example III was repeated except that 0.1% wax polyisobutylene mixture was added to the petrolatum, and the back pressure increased to 36 psi.
  • the foamed product had a microscopic cell structure and a cupweight of 129 gms. per 100 ml.
  • the foamed products of Examples II, III and IV were injection molded into a braided hose and allowed to set.
  • a petrolatum as in Example I was foamed in the aforedescribed manner (with assurance that the mixing head was cooled) both with and without a polymeric stabilizer, and further compared with a control sample showing the dielectric constant prior to foaming, as follows:
  • the foamed products of Samples 1 and 2 had densities of 520 kg/m 3 and 510 kg/m 3 respectively, and exhibited dielectric constants at 500 V at 50 Hz as follows:
  • Example VI The composition of Example VI were filled into a multi-conductor cable as shown in Figs. 1 and 2.
  • the contemplation of this invention to include certain limited percentages of other materials in the petrolatum composition, such as polyolefins and additional waxes with melting points up to 220°F, particularly relatively high percentages of microcrystalline waxes.
  • Synthetic waxes are also preferred and include Fischer-Tropsch waxes or polyethylene waxes, ester waxes and the like. Natural waxes such as montan, candelilla, carnauba, are also useful. Microcrystalline waxes or other materials that tend to be readily reduced to fine particulates are most preferred.
  • the composition of the present invention may be formed by one of several known foaming techniques to provide a foam having up to about 55% by volume of a gas in a closed-cell configuration. Particularly suited foaming operations are those mechanical processes involving agitation and whipping action. It has been found that foam cup weight may be 90 gm/200 ml to 135 gm/200 ml and preferably 95 gm/200 ml; although cup weights less than 90 gm/200 ml and more than 135 gm/200 ml have been found useful.
  • the resultant filler should have a dielectric constant of less than 5 and preferably less than 2, and the foam produced pursuant to this invention has been found to exhibit a dielectric constant less than 2.
  • Cables containing the foamed petrolatum as a filler can be fabricated by suitable techniques well known in the.art.
  • An exemplary technique for fabricating a twisted, multi-pair communication cable includes the steps of passing a plurality of twisted pairs of insulated conductors in a forming zone to produce a bundle of the conductors and subsequently passing the bundle of the conductors through a stuffer box.
  • the stuffer box is connected to an injection pump by means of a conduit which serves to inject the foamed petrolatum from the pump to the stuffer box.
  • the foamed composition is passed through the side of the stuffer box under sufficient pressure to force it into the interstices between the several insulated conductors.
  • the stuffer box can be adjusted to provide a layer of the petrolatum composition around the periphery of the bundle of conductors.
  • the bundle of conductors including the foamed composition disposed within the bundle is passed from the stuffer box to a core wrapping machine which longitudinally folds first a strip of paper and then a strip of aluminum around the bundle.
  • the strip of aluminum has an adhesive coating of a random copolymer of ethylene and acrylic acid on both sides for the purpose of achieving a bond between the overlapped edges of the strip.
  • the bundle having the core as its outer-most surface is passed through a crosshead die attached to an extruder which extrudes a sheath layer of polyethylene containing carbon black around the core wrap.
  • the resulting cable is then collected on a take-up reel. While the several foregoing steps can be performed individually with interruptions between each step, it is generally preferred that the cable be fabricated on a continuous basis to avoid the necessity of using storage reels between the several steps.

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  • Insulated Conductors (AREA)
  • Organic Insulating Materials (AREA)
EP82200424A 1981-12-09 1982-04-05 Geschäumte Petrolatum-Kabelfüllmasse Withdrawn EP0081248A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US32896681A 1981-12-09 1981-12-09
US328966 1981-12-09

Publications (1)

Publication Number Publication Date
EP0081248A1 true EP0081248A1 (de) 1983-06-15

Family

ID=23283249

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82200424A Withdrawn EP0081248A1 (de) 1981-12-09 1982-04-05 Geschäumte Petrolatum-Kabelfüllmasse

Country Status (2)

Country Link
EP (1) EP0081248A1 (de)
JP (1) JPS58102407A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000026925A1 (en) * 1998-11-04 2000-05-11 Shrieve Chemical Products, Inc. Environmentally friendly dielectric fluids
US6169160B1 (en) 1996-09-26 2001-01-02 Union Camp Corporation Cable protectant compositions
CN102277222A (zh) * 2011-05-20 2011-12-14 天津市百润石油制品有限公司 一种工业凡士林及其制备方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3060136A (en) * 1959-08-05 1962-10-23 Socony Mobil Oil Co Inc Foamed wax composition containing a major proportion of wax and a minor proportion of rubber
DE2243615A1 (de) * 1972-09-01 1974-03-07 Siemens Ag Laengsdichtes nachrichtenkabel
EP0037611A1 (de) * 1980-04-07 1981-10-14 Witco Chemical Corporation Geschäumte Kabelfüllmasse und solche Füllmasse enthaltendes Kabel
EP0039867A2 (de) * 1980-05-12 1981-11-18 Siemens Aktiengesellschaft Längswasserdichtes Kabel, insbesondere Nachrichtenkabel

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3060136A (en) * 1959-08-05 1962-10-23 Socony Mobil Oil Co Inc Foamed wax composition containing a major proportion of wax and a minor proportion of rubber
DE2243615A1 (de) * 1972-09-01 1974-03-07 Siemens Ag Laengsdichtes nachrichtenkabel
EP0037611A1 (de) * 1980-04-07 1981-10-14 Witco Chemical Corporation Geschäumte Kabelfüllmasse und solche Füllmasse enthaltendes Kabel
EP0039867A2 (de) * 1980-05-12 1981-11-18 Siemens Aktiengesellschaft Längswasserdichtes Kabel, insbesondere Nachrichtenkabel

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6169160B1 (en) 1996-09-26 2001-01-02 Union Camp Corporation Cable protectant compositions
WO2000026925A1 (en) * 1998-11-04 2000-05-11 Shrieve Chemical Products, Inc. Environmentally friendly dielectric fluids
CN102277222A (zh) * 2011-05-20 2011-12-14 天津市百润石油制品有限公司 一种工业凡士林及其制备方法

Also Published As

Publication number Publication date
JPS58102407A (ja) 1983-06-18

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19840525

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Inventor name: DOORN, JOHANNIS