Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1999-08-09
2001-05-08
Krynski, William (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S375000, C428S378000, C174S02300R, C174S1130AS, C174S1100PM, C174S1100SR
Reexamination Certificate
active
06228495
ABSTRACT:
The present invention pertains to a polyolefin composition for use as insulation for wire and cable that has improved resistance to the deleterious effects of heat, oxygen and moisture. The stabilized compositions are suitable for use as telecommunications (telecom) cable.
BACKGROUND OF THE INVENTION
A typical telecom cable is constructed of twisted pairs of polyolefin-insulated copper wire which are bundled together and protected by a cable sheath. The cable sheath is composed of a metal foil and/or armor in combination with a polymeric jacketing material. The entire system is referred to as “telecom cable”.
To reduce the risk of water penetration into the cable system and to minimize the deleterious effects of moisture on the polyolefin insulation, the system is made water-tight by filling the voids in the cable with a hydrophobic grease. Cable systems of this type are described for example in U.S. Pat. Nos. 3,888,709, 4,044,200, 4,218,577, 5,502,288 and European patent application 565,868 A2, and the references therein. The cable filler grease is known to extract stabilizers incorporated into the wire insulation. This is discussed for example in “Plastics Additives Handbook”, 3
rd
Edition, R. Gälchter, H. Müller, Eds., Hanser Publishers, pages 116-119 (1990)].
Junctions of two or more telecom cables are often required and this is accomplished in an outdoor enclosure known as a pedestal or an interconnection box. Inside the pedestal, the cable sheathing is removed, the cable filler grease is wiped off, and the transmission wires are joined as necessary. The exposed insulated wires are now subject to the adverse conditions of heat, oxygen and moisture. The polyolefin insulation, having lost a portion of its stabilizer additives to extraction by the filler grease, is especially vulnerable to these environmental conditions and may exhibit premature oxidative failure. This failure exhibits itself in the loss of physical properties of the insulation which ultimately results in a loss of electrical transmission performance.
The stabilization of polyolefin wire insulation in telecom applications with hindered phenolic antioxidants is known. A state of the art stabilizer system includes the use of a hindered phenol together with a metal deactivator such as IRGANOX® MD 1024, 1,2-bis(3,5-di-tert-butyl4-hydroxyhydrocinnamoyl)hydrazine or NAUGARD® XL-1, 2,2′-oxalyldiamido-bis-[ethyl 3-(3,5-di-tert-butyl4-hydroxylphenyl)propionate]. A typical stabilizer package includes, as the primary antioxidant, IRGANOX® 1010, pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and as the metal deactivator, IRGANOX® MD 1024. This system is disclosed in European patent application 565,868 A2 and U.S. Pat. Nos. 4,044,200, 5,380,591 and 5,575,952. IRGANOX® is a protected trade name of Ciba Specialty Chemicals Corp., NAUGARD® is a protected trade name of Uniroyal.
U.S. Pat. No. 4,044,200 discloses the stabilization of polyethylene wire insulation in the presence of a moisture barrier filler with a combination of an alkylhydroxyphenylalkanoyl hydrazide and/or a substituted amido triazole together with a high molecular weight hindered phenolic antioxidant. Specifically disclosed is the combination of IRGANOX® MD 1024 and IRGANOX® 1010.
U.S. Pat. No. 4,812,500 discloses a polyolefin composition having improved resistance to deterioration when exposed to hot oxygenated water, chlorinated water, and Uv radiation. The composition comprises a hindered amine UV stabilizer, a hindered phenolic thermal stabilizer and a chelating (metal deactivating) agent. The hindered phenolic is selected from a specific group including IRGANOX® 1010, pentaerytiritol tetrakis [3-(3,5-di-tert-butyl4-hydroxyphenyl)propionate], and IRGANOX® 3114, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate. The chelating agent is selected from a group including IRGANOX® MD 1024, 1,2-bis(3,5di-tert-butyl-4-hydroxyhydrocinnamoyl)hydrazine. IRGANOX® is a trademark of Ciba Specialty Chemicals Corp. It is contemplated that the invention may be used for various systems where water or moisture are present, including wire and cable coatings. There is no mention of grease filled cable systems where the potential for extraction of the additives exists.
U.S. Pat. Nos. 5,380,591, 5,453,322, 5,575,952, 5,766,761 and 5,807,635 disclose the stabilization of hydrocarbon grease filled telephone cables with the combination of a mixture of an alkylhydroxyphenylalkanoyl hydrazine with a functionalized hindered amine. IRGANOX® MD 1024 is specifically disclosed as the hydrazine in each case.
U.S. Pat. No. 5,474,847 teaches the stabilization of polyolefin wire insulation in grease filled telephone cables with the reaction products of hydrazide derivatives of hindered phenols or hindered amines or amino derivatives of hindered amines with a quinone.
U.S. Pat. No. 5,502,288 discloses the stabilization of polyolefin wire insulation in telephone cables with the use of IRGANOX® MD 1024 or NAUGARD® XL-1 or mixtures thereof with selected antioxidants.
European patent application 565,868 A2 teaches the stabilization of polyolefin wire insulation compositions exposed to water-blocking cable fillers with a combination of divalent metal salts of phenolic carboxylic or phosphonic acids together with a metal deactivator. Specifically named metal deactivators are IRGANOX® MD 1024 and NAUGARD® XL-1. A preferred composition also includes the use of IRGANOX® 1010.
WO 93/24935 teaches the use of the reaction products of an anhydride of an unsaturated aliphatic diacid with one or more functionalized hindered amines and/or functionaiized hindered phenols for the stabilization of polyolefin wire insulation in grease filled telephone cables.
WO 93/24938 discloses a grease filled cable construction in which the polyolefin wire insulation which has bonded to it, through an anhydride of an aliphatic diacid, one or more functionalized hindered amines and/or functionalized hindered phenols.
In order to protect the polyolefin wire insulation that is exposed to enviromnental conditions in the interconnection box, and to counteract the extraction of stabilizers by the cable filler grease, it has been suggested that high loadings of the stabilizer system be employed. There is a need to find more efficient primary antioxidant/metal deactivator combinations than those that are the state of the art in order to reduce the high cost associated with the use of these levels of stabilizers. Stabilizer efficiency in this context is the combined ability of the stabilizer system to resist extraction from the polyolefin wire insulation into the cable filler grease and to provide the polyolefin with resistance to the deleterious effects of heat, oxygen and moisture.
Surprisingly, it has been found that the combination of one or more primary phenolic antioxidants selected from IRGANOX® 1098, N,N′-hexane-1,6-diylbis-(3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)), IRGANOX® 3114, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, and IRGANOX® 3125, tris(2-(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyloxy)ethyl)isocyanurate, together with one or more alkylhydroxyphenylalkanoyl hydrazine metal deactivators is especially effective towards providing oxidative stability for polyolefin wire insulation in grease filled telecom cables. IRGANOX® is a trademark of Ciba Specialty Chemicals Corp.
DETAILED DESCRIPTION OF THE INVENTION
The present invention pertains to a novel hydrocarbon grease filled cable construction wherein the polyolefin wire insulation has improved oxidative stability.
More particularly, the novel cable construction of this invention comprises
(i) a plurality of insulated electrical conductors having interstices therebetween,
said insulation comprising
(a) one or more polyolefins, and
(b) one or more primary antioxidants selected from the group of N,N′-hexane-1,6-diylbis-(3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide)), tris(3,5-di-tert-butyl4-hydroxybenzyl)isocyanurate and tris(2-(3,5-di-tert-butyl-4-hydroxyhydrocinna
Fay Joseph
Lupia Joseph
Ciba Specialty Chemicals Corporation
Gray J. M.
Hall Luther A. R.
Krynski William
Stevenson Tyler A.
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