MXPA99006524A - Telephone cables - Google Patents

Abstract

A cable construction comprises the following components:(i) a plurality of insulated electrical conductors having interstices therebetween, said insulation comprising (a) one or more polyolefins selected from the group consisting of polyethylene, polypropylene, and mixtures thereof, and, blended therewith, (b) a mixture containing one or more alkylhydroxy-phenylalkanoyl hydrazines and one or two functionalized hindered amines;(ii) hydrocarbon cablefiller grease within the inerstices;and (iii) a sheath surrounding components (i) and (ii) wherein said hindered amines have structural formulae:Formula (I), wherein n is about 2 to about 12;R is CxHyOz wherein x is about 2 to about 6, y is about 4 to about 16, and z is zero to about 3;Formula (II), wherein m is about 2 to about 30;n is about 2 to about 30;and x is about 1 to about 30;or Formula (III), wherein n is about 2 to about 20.

Description

TELEPHONE CABLES TECHNICAL FIELD This invention relates to wire and cable and to the insulation and coating thereof and, more particularly to a telephone cable. - BACKGROUND OF THE INVENTION A typical telephone cable consists of twisted pairs of metallic conductors for signal transmission. Each conductor is insulated with a polymeric material. The desired number of transmission pairs is assembled in a circular cable core protected by a cable jacket incorporating a metal foil and / or armature in combination with a polymeric casing material. The cover protects the transmission core against mechanical damage and, to some extent, environmental damage. Phone cables stuffed with grease are especially interesting. These cables were developed in order to minimize the risk of water penetration that can seriously affect the quality of the transmission of electrical signals. A waterproof cable is provided by filling the air spaces in the interstices of the cable with a hydrocarbon cable filler grease. While the cable filler grease removes a portion of the anti-oxidants from the insulation, the impervious cable does not fail due to premature oxidation to the extent that the cable retains its integrity. In the cable transmission network, however, the connections of two or more waterproof cables are required and this connection is often achieved in an external enclosure known as a pedestal (a box of interconnections). Inside the pedestal, the cable jacket is removed, the cable filling grease is removed, and the transmission wires are interconnected. The pedestal with its isolated wires now exposed is usually subjected to a severe environment, a combination of high temperature, air, and humidity. This environment together with the bulging of these antioxidants currently used in the cable filled with grease can cause the insulation on the pedestal to show a failure by premature oxidation. In its final stage, this failure is reflected in a fragile insulation from the perspective of oxidation that tends to form cracks and separate into sheets together with a loss of electrical transmission performance. To counteract the depletion of antioxidants, it has been proposed to add high levels of antioxidants to the polymeric insulation. However, this not only alters the performance characteristics of the insulator but is economically unsatisfactory considering the high cost of antioxidants. Therefore, there is a need for antioxidants that resist the extraction of cable filler grease in a necessary quantity to avoid failures due to premature oxidation and ensure the 30-40 year lifespan desired by the industry. SUMMARY OF THE INVENTION An object of the present invention is therefore to provide a cable construction filled with fat containing antioxidants, which will resist extraction and will be maintained at a satisfactory level of stabilization. Other objects and advantages will be apparent below. In accordance with the present invention, a cable construction that meets the aforementioned object has been discovered. The cable construction comprises the following components (i) a plurality of insulated electrical conductors having interstices therebetween, said insulation comprising (a) one or more selected polyolefins within the group consisting of polyethylene, polypropylene, and mixtures thereof and, together with them, (b) a mixture containing one or more alkylhydroxy-phenylalkanoyl hydrazines and one or two hindered functionalized amines; (ii) a hydrocarbon cable filler grease within the interstices; (iii) an envelope that wraps the components (i) and (iii) wherein said hindered amines have the following structural formulas: Formula I where n is from about 2 to about 12; R is CxHyOz where x is from about 2 to about 6, and is from about 4 to about 16, and z is from about 0 to about 3; Formula II where m is from about 2 to about 30; n is from about 2 to about 30, and x is from about 1 to about 30; or Formula III where n is from about 2 to about 20. Description of preferred embodiments The polyolefins employed in this invention are generally thermoplastic resins that are crosslinkable. They can be homopolymers or copolymers produced from 2 or more comonomers, or a mixture of 2 or more of these polymers, conventionally used in film, sheet and tube and as wrapping materials and / or insulation in applications in wires and cables . The monomers useful in the production of these homopolymers and copolymers can have from 2 to 20 carbon atoms, and preferably have from 2 to 12 carbon atoms. Examples of these monomers are alpha olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pendant, and 1-octene; unsaturated esters such as for example vinyl acetate, ethyl acrylate > methyl acrylate, methyl methacrylate, t-butyl acrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, and other alkyl acrylates; diolefins such as for example 1,4-pentadiene, 1,3-hexadiene, 1,5-hexadiene, 1,4-octadiene, and ethylene norbornene, commonly, the third monomer in a terpolymer; other monomers such as for example styrene, p-methylstyrene, alpha-methylstyrene, p-chlorostyrene, vinylnaphthalene, and similar arylolefins; nitriles such as, for example, acrylonitriles, methacrylonitrile, and alpha-chloroacrylonitrile; vinyl methyl ketone, vinyl methyl ether, vinylidene chloride, maleic anhydride, vinyl chloride, vinylidene chloride, vinyl alcohol, tetrafluoroethylene, and chlorotrifluoroethylene; and acrylic acid, methacrylic acid, and other similar unsaturated acids. The mentioned homopolymers and copolymers can be non-halogenated or halogenated in a conventional manner, generally with chlorine or bromine. Examples of halogenated polymers are polyvinyl chloride, polyvinylidene chloride, and polytetrafluoroethylene. Homopolymers and copolymers of ethylene and propylene are preferred, both in non-halogenated form and in halogenated form. Preferred in this preferred group are terpolymers, such as, for example, ethylene / propylene / diene monomer rubbers. Other examples of ethylene polymers are the following: a high pressure ethylene homopolymer; a copolymer of ethylene and one or more alpha olefins having from 3 to 12 carbon atoms; a copolymer or ethylene copolymer having a hydrolysable silane grafted to its structures; a copolymer of ethylene and an alkenyltrialkoxysilane such as for example trimethoxyvinyl silane; or a copolymer of an alpha olefin having from 2 to 12 carbon atoms and an unsaturated ester having from 4 to 20 carbon atom, for example ethylene / ethyl acrylate or vinyl acetate copolymer; a terpolymer of ethylene / ethyl acrylate or vinyl acetate / silane hydrolyzable; and ethylene / ethyl acrylate or vinyl acetate copolymers having a hydrolysable silane grafted to their structures. As regards polypropylene: homopolymers and copolymers of propylene and one or more other alpha olefins where the propylene-based copolymer portion is at least about 60% by weight based on the weight of the copolymer can be used to provide the polyolefin of the present invention. The polypropylene can be prepared by conventional processes such as for example the process described in U.S. Patent No. 4,414,132. The alpha-olefin polypropylene comonomers are those having 2 or 4 to 12 carbon atoms. The homopolymer or copolymers can be crosslinkable either cured with an organic peroxide or to make them hydrolysable, they can be grafted with an alkenyltrialcixysilane in the presence of an organic peroxide which acts as a free radical generator or catalyst. Useful alkenyltrialkoxysilanes include vinyltrialkoxysilanes such as for example vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltriisopropoxysilane. The alkenyl and alkoxy radicals may have from 1 to 30 carbon atoms and preferably have from 1 to 12 carbon atoms. The hydrolysable polymers can be cured with moisture in the presence of a silanol condensation catalyst, such as, for example, dibutyltin dilaurate, dioctyltin maleate, stannous acetate, stannous octoate, lead naphthenate, zinc octoate, iron 2-ethyl hexoate. , and other metal carboxylates. Ethylene homopolymers or copolymers where ethylene is the primary comonomer and propylene homopolymers and copolymers where propylene is the primary comonomer can be referred to herein as polyethylene and polypropylene, respectively. For each 100 parts by weight of polyolefin, the other components of the isolation mixture may be present in approximately the following proportions: Parts in Weight Wide Range Preferred Range (i) Hydrazine at least 0.1 from 0.3 to 2.0 (ii) amine hindered at less 0.01 from 0.05 to 1.0 (iii) fat from 3 to 30 from 5 to 25 Regarding hydrazine and hindered amine, there is no upper limit except the practical limits, which are determined by economic factors, ie the cost of antioxidants. In accordance with this perspective, the most preferred upper limits are about 1.0 and about 0.5 part by weight, respectively. The weight ratio between hydrazine and the hindered amine may be within the range of about 1: 1 to about 20: 1, and it is preferable that it be within the range of about 2: 1 to about 15: 1. A more preferred ratio is from about 3: 1 to about 10: 1. It will be noted that the hindered amine is effective for use at very low levels relative to hydrazine. In US Patent Nos. 3,660,438 and 3,773,722, alkylhydroxyphenylallanyl hydrazines are described. A preferred general structural formula for hydrazines useful in accordance with the present invention is as follows: where n is n is 0 or an integer from 1 to 5; R1 is an alkyl having 1 to 6 carbon atoms; R2 is a hydrogen or R1; and R3 is hydrogen, an alkanoyl having from 2 to 18 carbon atoms, or the following structural formula: where n, Rl and R2 are identical to the aforementioned. The hindered amines useful in this invention have a limited solubility in the hydrocarbon cable filler fat described below. An analogy can be drawn between solubility in filler fat and solubility in n-hexane at 202C. Thus, each of the hindered amines has a solubility in n-hexane at a temperature of less than about 1% by weight based on the weight of n-hexane. The hindered amines are presented above as formulas I, II, and III. Note: the terminal groups can be hydrogen, hydroxide, methoxy, or another conventional termination group. A specific example of formula I is the hindered amine Hostavin (registered trademark) N30, CAS registry number 162731, available from Hoechst-Celanese. A specific example of Formula I is the hindered amine Lo ilite (registered trademark) 62, formerly available from Lo i Chemical Company. It is a product of the reaction of alpha-methyl styrene; N- (2,2,6,6-tetramethyl-piperidinyl-4) maleimide; and N-steryl-maleimide. A specific example of formula III is poly ((methyl-methacrylate) -co- (4 (2,2,6,6-tetramethyl) -piperidin-4-ol) acrylate)) available from Ferro Corporation, as protection against radiation UVAN-806, CAS registry number 115340-81-3. A hydrocarbon cable filler grease is a mixture of hydrocarbon compound that is in a semi-solid state at temperatures of use. It is known in the industry as "cable filling compound". A typical requirement for cable filler compounds is that the grease has a minimum leak from the cut end of a cable at a temperature of 602C or more. Another typical requirement is that the grease resists water leakage through a short length of cut wire when water pressure is applied at one end. Among other typical requirements are cost competitiveness; minimal negative effect on the transmission of signals; minimal negative effect on the physical characteristics of polymer insulation, and cable coating materials; thermal stability and oxidation; and processing capacity for cable manufacturing. The cable fabrication can be achieved by heating the cable filler compound to a temperature of about 100 degrees C. This liquifies the filler compound in such a way that it can be pumped into a multi-conductor cable core to completely impregnate the interstices and eliminate all the air space. Alternatively, thixotropic cable filler compounds can be processed by using subjuvant cutting at reduced temperatures in the same manner. A cross section of a cable transmission core filled with typical finished grease consists of approximately 52% insulated wire and approximately 48% interstices in terms of the total cross-sectional areas. Since the interstices are fully filled with the cable filler compound, a filled cable core typically contains approximately 48% by volume of cable filler compound. The cable filling compound or one or more of its hydrocarbon constituents penetrates the insulation through the absorption of the interstices. Generally, the insulation absorbs from about 3 to about 30 parts by weight of a cable filler compound or one or more of its hydrocarbon constituents, in total, based on 100 parts by weight of polyolefin. A typical absorption is within the range of a total of about 5 to about 25 parts by weight per 100 parts of polyolefin. It will be observed by those skilled in the art that the combination of resin, constituents of cable filler compound, and antioxidants in the insulation is more difficult to stabilize than an insulating layer containing only resin and antioxidant, and that it does not contain constituent of cable filling compound. Examples of hydrocarbon cable filler grease (cable filler compound) are petrolatum; petrolatum / polyolefin wax mixtures; thermoplastic rubber modified with oil (ETPR or extended thermoplastic rubber); paraffin oil; naphthalic oil; mineral oil; the aforementioned oils thickened with a residual oil, petrolatum, or wax; polyethylene wax; mineral oil / rubber block copolymer mixture; lubricant grease; and various mixtures thereof, all of which meet industrial requirements similar to those described above. In general, cable filler compounds extract isolation antioxidants and, as noted above, are absorbed in polymeric insulation. Since each cable filling compound contains hydrocarbon bars, both the absorption behavior and the extraction behavior are preferential towards the lower molecular weight hydrocarbon wax and constituents of the oil. It is found that the isolation composition with its antioxidant not only has to resist extraction, but also has to provide sufficient stabilization (i) to mediate against the copper conductor, which is a potential catalyst for the oxidative degradation of isolation; (ii) to counteract the effect of residues of chemical expansion agents present in insulation in the form of polymer foam (foam / skin) cellular and cellular / solid; and (iii) to counteract the effect of absorbed constituents of the cable filler compound. The polyolefin may be a polyolefin or a mixture of polyolefins. The hydrazine and the hindered hindered amine are mixed with the polyolefin. The composition containing the above can be used in combination with disulfides, phosphites or other antioxidants which are not amines at molar ratios of about 1: 1 to about 1: 2 for additional oxidative and thermal stability, but must obviously end in what measure these last compounds are extracted by fat since this would affect the effectiveness of the combination. The following conventional additives can be added in conventional amounts if desired: ultraviolet radiation observers, antistatic agents, pigments, colorants, fillers, glidants, flame retardants, stabilizers, crosslinking agents, halogen scavengers, smoke inivers, reinforcers crosslinking, processing aids, etc., metal carboxylates, lubricants, plasticizers, viscosity control agents, and blowing agents such as azodicarbonamide. Fillers may include, among others, magnesium hydroxide and alumina trihydrate. As noted, other metal antioxidants and / or deactivators may also be employed, but for these or for any other additives, resistance to grease removal must be taken into consideration. Additional information regarding the cable filled with grease can be found in Eoll, The Aging of Filled Cable with Cellular Insulation, (the aging of cable filled with cellular insulation), International Wire & Cable Symposium Proceeding 1978 (minutes from the International Wire and Cable Symposium, 1978, pages 156-170, and Mitchel et al, Development, Characterization, and Performance of an Improved Cable Filling Compound (development, characterization and performance of an improved cable compound , International Wire &Cable Symposium Proceeding 1980 Sminutes of the International Wire and Cable Symposium 1980, pages 15 to 25. This latest publication shows a typical cable construction on page 16 and offers additional examples of cable filler compounds.

The patents and other publications mentioned in this specification are incorporated herein by reference. The invention is illustrated through the following examples.

EXAMPLES 1-4 The various materials used in the examples are the following: Polyethylene I is a copolymer of ethylene and 1-exoene. The density is 0.946 gram per cubic centimeter and the melting index is 0.80 to 0.95 gram per 10 minutes. The antioxidant A is l, 2-bis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamoyl) hydrazine. The antioxidant B in the specific example of the aforementioned formula I. The antioxidant C specific example of the formula II mentioned above. The antioxidant D is the exemplary rate of formula III mentioned here. 10-mil polyethylene plates were prepared for oxidation induction time (OIT) test. The plates are prepared from a mixture of polyethylene and the antioxidants mentioned above. The parts by weight of each one is established in the attached tables.

A laboratory procedure that simulates the application of cable filled with grease is used to demonstrate performance. Resin samples are prepared that incorporate specific antioxidants. Samples are first formed into pellets and then formed on 10-mil thick (0.010-inch) test plates, using AFTMD-1928 methods as a guideline. There is a final melt blend in a two roll mill, or in a Brabender (TM) type laboratory mixer followed by the preparation of the test plates using a 150sec compression molding press. The induction or initial oxygen time is measured in these test plates. A supply of hydrocarbon cable filler grease is heated to a temperature of about 80 ° C and mixed well to ensure uniformity. A supply of 30 mm flasks is then filled to approximately 25 mm with the cable filling grease. These bottles are then cooled to room temperature for subsequent use. An oil-extended thermoplastic rubber-type cable filler grease (ETPR) is the hydrocarbon cable filler grease used in these examples. It is a typical cable filler compound. Each 10 mil test plate is then cut to provide approximately 20 test samples of approximately 0.5 square inch. Before the test, each bottle is heated again to a temperature of about 70 ° C to allow easy insertion of the test samples. The samples are inserted into the bottle one by one together with careful wetting of all surfaces with the cable filling grease. After the insertion of all the samples, the bottles are covered in a loose way and placed in a circulating air oven at a temperature of 70 ° C. The mixtures are removed after 1.2 and four weeks. The samples are then cleaned of cable filling grease with a cloth and aged in an air oven at a temperature of 90 ° C. A sample is then removed after 4 weeks at 90 ° C (eight weeks of total aging). The initial samples, one week, 2 weeks, 4 weeks and 8 weeks are tested for OIT. The OIT test is carried out in a differential scanning calorimeter with an ILO test cell. The test conditions are: an aluminum container without folds; without sieve; heating at 200 ° C under a nitrogen atmosphere followed by a change to a flow of 50 millimeters of oxygen. The oxidation induction time (OIT) is the time interval between the start of the oxygen flow and the exothermic decomposition of the test sample. The ILO reports in minutes. The higher the number of minutes the better the ILO. The ILO is used as a measure of the oxidation stability of a sample as it progresses through the exposure of cable filler grease and the oxidizing aging program. A relative performance in cable applications filled with grease can be predicted by comparing the OIT of an initial sample with the OIT values after exposure of cable filler grease at 70 ° C and oxidative aging at 90 ° C. The variables and the results appear in the following table. Example 1 Example 2 Example 3 Example 4 (% by weight) Antioxidant A 0.5 0.5 0.5 0.5 Antioxidant B 0.1 none none none Antioxidant C none 0.1 none none Antioxidant D none none 0.1 none Polyethylene 99.4 99.4 99.4 99.5 ILO (minutes): Initial 248 200 193 176 1 Week 278 283 218 150 2 Weeks 264 249 237 163 4 Weeks 273 272 247 140 8 Weeks 248 229 236 99

Claims (10)

1. CLAIMS 1. A cable construction comprises the following components: (i) a plurality of insulated electrical conductors having interstices therebetween, said insulation comprising (a) one or more selected polyolefins within the group consisting of - polyethylene, polypropylene, and mixtures thereof and, mixed with them (b) a mixture containing one or more alkylhydroxy-phenylalkanoyl hydrazines and one or more functionalized hindered amines; (ii) hydrocarbon cable filler grease inside the interstices; and (iii) an envelope surrounding components (i) and (ii) wherein said hindered amines have the following structural formulas: Formula I where n is from about 2 to about 12; R is CxHyOz where x is from about 2 to about 6, and is from about 4 to about 16 and z is from 0 to about 3; Formula II where m is from about 2 to about 30; n is from about 2 to about 30; and x is about 1 about 30; or Formula III where n is from about 2 to about 20. The cable construction defined in claim 1, wherein the hydrazine has the following structural formula: wherein n is 0 or a number from 1 to 5; R1 is an alkyl having 1 to 6 carbon atoms; R 2 is hydrogen or R 1; and R3 is hydrogen, an alkanoyl having from 2 to 18 carbon atoms, or the following structural formula: where n, Rl, and R2 are the same as indicated above. The cable construction defined in claim 1, wherein for every 100 parts by weight of polyolefin, the hydrazine (s) is (are) present in an amount of at least about 0.1 part by weight and the hindered amine (s) is (are) present in an amount of at least about 0.1 part by weight. . The cable construction defined in claim 1, wherein the weight ratio between hydrazine and hindered amine is within the range of about 1: 1 to about 20: 1. The cable construction defined in claim 2, wherein the hydrazine is l, 2-bis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamoyl) hydrazine. The cable construction defined in claim 2, wherein the hindered amine is poly ((6-morpholino-s-triazine-2,4-diyl) (2,2,6,6-tetramethyl-4-piperidyl) imino) - hexamethylene ((2,2,6,6-tetramethyl-4-piperidyl)) iminol)) and / or poly ((6- ((1, 1,3, 3-tetramethylbutyl) amino) -s-triazine-2 , 4-diyl) ((2, 2, 6, 6-tet'ramethyl-4-piperidyl) imino) -hexamethylene ((2,2,6,6-tetramethyl-4-piperidyl) imino)). The cable construction defined in the claim, wherein the hydrocarbon cable filler grease or one or more of the hydrocarbon constituents thereof is present in the insulation of the component (i). The cable construction defined in claim 7, wherein the amount of hydrocarbon cable filler grease or one or more of the hydrocarbon constituents thereof, present in the insulation of component (i) is within the range of about 3 to about 30 parts by weight based on 100 parts by weight of polyolefin. A cable construction comprising the following components: (i) a plurality of insulated electrical conductors having interstices therebetween, said insulation comprising (a) one or more selected polyolefins within the group consisting of polyethylene, polypropylene, and mixtures thereof. and blended therewith (b) a mixture containing one or more alkylhydroxy-phenylalkanoyl hydrazines where the alkyl has from 1 to 6 carbon atoms and the alkanoyl has from 2 to 18 carbon atoms and one or two functionalized hindered amines (ii) ) a hydrocarbon cable filler grease inside the interstices; and (iii) an envelope surrounding components (i) and (ii) wherein said hindered amines have the following structural formulas: Formula I where n is from about 2 to about 12; R is CxHyOz where x is from about 2 to about 6, and is from about 4 to about 16, and z is from 0 to about 3; Formula II where m is from about 2 to about 30; n is from about 2 to about 30; and x is from about 1 to about 30; or Formula III where n is from about 2 to about 20. The cable construction defined in claim 9, wherein the weight ratio between the hydrazine and the hindered amine is within. from the range of about 3: 1 to about 10: 1 SUMMARY OF THE INVENTION A cable construction comprises the following components: (i) a plurality of insulated electrical conductors having interstices therebetween, said insulation comprising (a) one or more selected polyolefins within the group consisting of polyethylene, polypropylene, and mixtures thereof and, mixed with them (b) a mixture containing one or more alkylhydroxyphenylalkanoyl hydrazines and one or more functionalized hindered amines; (ii) hydrocarbon cable filler grease inside the interstices; and (iii) an envelope surrounding components (i) and (ii) wherein said hindered amines have the following structural formulas: Formula I where n is from about 2 to about 12; R is CxHyOz where x is from about 2 to about 6, and is from about 4 to about 16 and z is from 0 to about 3; Formula II where m is from about 2 to about 30; n is from about 2 to about 30; and x is about 1 about 30; or Formula III where n is from about 2 to about 20.