Plastic and nonmetallic article shaping or treating: processes – Reactive gas or vapor treatment of work – Work is organic material
Patent
1988-12-09
1990-04-10
Thurlow, Jeffery
Plastic and nonmetallic article shaping or treating: processes
Reactive gas or vapor treatment of work
Work is organic material
174102SC, 252511, 264105, 264117, 264118, 264122, 264174, 264211, 26421113, 2642112, 264236, B29C 4706, B29C 6700, B32B 2718, H01B 106
Patent
active
049158899
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of producing an electrically semi-conducting, strippable plastics mixture, in particular for use as screening material for electric wires and cables.
BACKGROUND OF THE INVENTION
Electric wires and cables, such as copper wires, are often covered with a coating material or a protective sheath, which may be a plastics material. Sometimes the wire or cable is coated with several layers, e.g. a combination of one or several layers of semi-conducting material, one or more layers of insulating material and possibly with a metal taping or metal braid and an outer sheath.
It is known to use a coating consisting of an electrically semi-conducting plastics mixture which must be strippable to allow wire or cable ends to be stripped for connection.
It is the object of the present invention to produce an electrically semi-conducting strippable plastics mixture which is suited for use as screening material for electric wires and cables.
DESCRIPTION OF THE PRIOR ART
GB patent specification No. 1 286 460 describes a method of producing a cross-linked polyolefin, in which thermoplastic polyethylene or a copolymer of ethylene and a small amount of propylene and/or butylene is mixed with an unsaturated hydrolyzable silane in the presence of a free-radical-forming compound, e.g. a peroxide, the reaction being carried out at a temperature preferably within the range 160.degree.-220.degree. C., whereafter the mixture or a shaped product thereof is moisture-exposed to complete the cross-linking reaction.
The known material thus produced possesses high stress crazing resistance and a high tensile strength.
Furthermore, it possess high organic solvent resistance.
Because of these properties, the material has been suggested for use as electric insulation material and for containers and tubes which come into contact with hot fluids. On the other hand, it has not been possible on the basis of such a mixture or on the basis of otherwise known techniques to produce satisfactory, electrically semi-conducting, strippable coating materials suited for live electric wires and cables.
GB patent specification No. 1 526 398 describes the production of similar cross-linked polyolefins or copolymerizates which are particularly suited for insulating electric cables and for tube manufacture. This material is not semi-conducting either. It is, however, possible to add carbon black, but only in small amounts, and with the aim of achieving coloring or protection against sunlight, but not of achieving semi-conducting properties.
In order to produce an electrically semi-conducting material it would be obvious to modify one of the above known processes by admixing larger amounts of comminuted carbon, such as carbon black. Experiments, however, have shown that no satisfactory cross-linking of the semi-conducting material and consequently unsatisfactory mechanical properties are obtained by that procedure.
SUMMARY OF THE INVENTION
According to the present invention it has now surprisingly been found that a cross-linkable material with optimum semi-conducting properties and which is also strippable can be obtained if the comminuted carbon is admixed when the other plastics components have been intimately mixed and the cross-linking agent already has reacted with the polymeric materials. The stated mixing order is decisive to the achievement of the aimed at electric and in particular mechanical properties at the cable operating temperature.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Thus the invention relates to a method of producing an electrically semi-conducting, strippable plastics mixture, in particular for use as screening material for electric wires and cables, according to which a polyolefin and/or a copolymerizate of several olefins is mixed with a hydrolyzable unsaturated organic silane, a free-radical-forming organic compound, possible suited plastics additives and hot comminuted carbon, the method being characterized in that a premix containing the polyolefin and/or the copolymerizate of olefins,
REFERENCES:
patent: 2930083 (1960-03-01), Vostovich et al.
patent: 3946099 (1976-03-01), Mackenzie, Jr.
patent: 4008113 (1977-02-01), Glander et al.
patent: 4046849 (1977-09-01), Lever et al.
patent: 4058583 (1977-11-01), Glander et al.
patent: 4117195 (1978-09-01), Swarbrick et al.
patent: 4136132 (1979-01-01), Poole
patent: 4297310 (1981-10-01), Akutsu et al.
patent: 4489029 (1984-12-01), Keogh et al.
patent: 4493787 (1985-01-01), Taniguchi et al.
patent: 4534889 (1985-08-01), Van Konynenburg et al.
patent: 4581158 (1986-04-01), Lin
patent: 4592861 (1986-06-01), Bekele et al.
patent: 4592862 (1986-06-01), Nakamura et al.
patent: 4655964 (1987-04-01), Steinberger et al.
patent: 4716000 (1987-12-01), Kerschbaum et al.
patent: 4767894 (1988-08-01), Schomobourg
Poulsen Keld V.
Procida Inger-Margrete
NKT A/S
Tentoni Leo B.
Thurlow Jeffery
LandOfFree
Method of producing an electrically semi-conducting, strippable does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of producing an electrically semi-conducting, strippable , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of producing an electrically semi-conducting, strippable will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2298105