WO1993024938A1

WO1993024938A1 - Telephone cables

Info

Publication number: WO1993024938A1
Application number: PCT/US1993/004884
Authority: WO
Inventors: Michael John Keogh; Geoffrey David Brown
Original assignee: Union Carbide Chemicals & Plastics Technology Corporation
Priority date: 1992-05-26
Filing date: 1993-05-24
Publication date: 1993-12-09
Also published as: MX9303054A

Abstract

An article of manufacture comprising (i) a plurality of electrical conductors, each surrounded by one or more layers comprising one or more polyolefins having bonded thereto, through an anhydride of an unsaturated aliphatic diacid, one or more functionalized hindered amines and/or functionalized hindered phenols and (ii) hydrocarbon cable filler grease within the interstices between the surrounded conductors.

Description

TELEPHONE CABLES

Technical Field

This invention relates to wire and cable and the insulation and jacketing therefor and, more particularly, to telephone cable.

Background Information

A typical telephone cable is constructed of twisted pairs of metal conductors for signal transmission. Each conductor is insulated with a polymeric material. The desired number of transmission pairs is assembled into a circular cable core, which is protected by a cable sheath incorporating metal foil and/or armor in combination with a polymeric jacketing material. The sheathing protects the transmission core against mechanical and, to some extent, environmental damage.

Of particular interest are the grease-filled telephone cables. These cables were developed in order to minimize the risk of water penetration, which can severely upset electrical signal transmission quality. A watertight cable is provided by filling the air spaces in the cable interstices with a hydrocarbon cable filler grease. While the cable filler grease extracts a portion of the antioxidants from the insulation, the watertight cable will not exhibit premature oxidative failure as long as the cable maintains its integrity.

In the cable transmission network, however, junction of two or more watertight cables are required and this joining is often accomplished in an outdoor enclosure known as a pedestal (an interconnection box). Inside of the pedestal, the cable sheathing is removed, the cable filler grease is wiped off, and the transmission wires are interconnected. The pedestal with its now exposed insulated wires is usually subjected to a severe environment, a

SUBSTITUTE SHEET combination of high temperature, air and moisture. This environment together with the depletion by extraction of those antioxidants presently used in grease filled cable can cause the insulation in the pedestal to exhibit premature oxidative failure. In its final stage, this failure is reflected in oxidatively embrittled insulation prone to cracking and flaking together with a loss of electrical transmission performance.

To counter 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 insulation, but is economically unsound in view of the high cost of antioxidants. There is a need, then, for antioxidants which will resist cable filler grease extraction to the extent necessary to prevent premature oxidative failure and ensure the 30 to 40 year service life desired by industry.

Disclosure of the Invention

An object of the invention, therefore, is to provide a grease-filled cable construction containing antioxidants which will resist extraction and be maintained in the cable insulation at a satisfactory stabilizing level. Other objects and advantages will become apparent hereinafter.

According to the invention, an article of manufacture has been discovered, which meets the above object, comprising, as a first component, a plurality of electrical conductors, each surrounded by one or more layers comprising one or more polyolefins having bonded thereto, through an anhydride of an aliphatic diacid, one or more functionalized hindered amines and/or functionalized hindered phenols and, as a second component, hydrocarbon cable filler grease within the interstices between the surrounded conductors.

SUBSTITUTE SHEET In one other embodiment, the article of manufacture comprises first and second components; however, the layer(s) of the first component contain absorbed hydrocarbon cable filler grease or one or more of the hydrocarbon constituents thereof and, in another embodiment, the article of manufacture is comprised only of the first component wherein the layer(s) contain hydrocarbon cable filler grease or one or more of the hydrocarbon constituents thereof.

Description of the Preferred Embodiments

The polyolefins used in this invention are generally thermoplastic resins, which are crosslinkable. They can be homopolymers or copolymers produced from two or more comonomers, or a blend of two or more of these polymers, conventionally used in film, sheet, and tubing, and as jacketing and/or insulating materials in wire and cable applications. The monomers useful in the production of these homopolymers and copolymers can have 2 to 20 carbon atoms, and preferably have 2 to 12 carbon atoms. Examples of these monomers are alpha-olefins such as ethylene, propylene, 1-butene, 1-hexene, 4-methyl-l- pentene, and 1-octene; unsaturated esters such as 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 1,4-pentadiene, 1,3-hexadiene, 1,5-hexadiene, 1,4-octadiene, and ethylidene norbornene, commonly the third monomer in a terpolymer; other monomers such as styrene, p-methyl styrene, alpha-methyl styrene, p-chloro styrene, vinyl naphthalene, and similar aryl olefins; nitriles such as acrylonitrile, methacrylonitrile, and alpha- chloroacrylonitrile; vinyl methyl ketone, vinyl methyl ether, vinylidene chloride, maleic anhydride, vinyl chloride, vinylidene chloride, vinyl alcohol, tetrafluoroethylene, and

SUBSTITUTE SHEET chlorotrifluoroethylene; and acrylic acid, methacrylic acid, and other similar unsaturated acids.

The homopolymers and copolymers referred to 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. The homopolymers and copolymers of ethylene and propylene are preferred, both in the non-halogenated and halogenated form. Included in this preferred group are terpolymers such as ethylene/propylene/diene monomer rubbers.

Other examples of ethylene polymers are as follows: a high pressure homopolymer of ethylene; a copolymer of ethylene and one or more alpha-olefins having 3 to 12 carbon atoms; a homopolymer or copolymer of ethylene having a hydrolyzable silane grafted to their backbones; a copolymer of ethylene and a hydrolyzable silane; or a copolymer of an alpha-olefin having 2 to 12 carbon atoms and an unsaturated ester having 4 to 20 carbon atoms, e.g., an ethylene/ethyl acrylate or vinyl acetate copolymer; an ethylene/ethyl acrylate or vinyl acetate/hydrolyzable silane terpolymer; and ethylene/ethyl acrylate or vinyl acetate copolymers having a hydrolyzable silane grafted to their backbones.

With respect to polypropylene: homopolymers and copolymers of propylene and one or more other alpha-olefins wherein the portion of the copolymer based on propylene is at least about 60 percent by weight based on the weight of the copolymer can be used to provide the polyolefin of the invention. The polypropylene can be prepared by conventional processes such as the process described in United States patent 4,414,132. The alpha-olefins in the copolymer are preferably those having 2 or 4 to 12 carbon atoms.

The homopolymer or copolymers can be crosslinked or cured with an organic peroxide, or to make them hydrolyzable, they can be grafted with an alkenyl trialkoxy silane in the presence of an

SUBSTITUTE SHEET organic peroxide which acts as a free radical generator or catalyst. Useful alkenyl trialkoxy silanes include the vinyl trialkoxy silanes such as vinyl trimethoxy silane, vinyl triethoxy silane, and vinyl triisopropoxy silane. The alkenyl and alkoxy radicals can have 1 to 30 carbon atoms and preferably have 1 to 12 carbon atoms. The hydrolyzable polymers can be moisture cured in the presence of a silanol condensation catalyst such as dibutyl tin dilaurate, dioctyl tin maleate, stannous acetate, stannous octoate, lead naphthenate, zinc octoate, iron 2-ethyl hexoate, and other metal carboxylates.

The homopolymers or copolymers of ethylene wherein ethylene is the primary comonomer and the homopolymers and copolymers of propylene wherein propylene is the primary comonomer may be referred to herein as polyethylene and polypropylene, respectively.

Anhydrides of unsaturated aliphatic diacids having 4 to 20 carbon atoms, and preferably 4 to 10 carbon atoms, can be used to provide the means for bonding or coupling the hindered phenol and/or hindered amine to the polyolefin. The bonding can be accomplished in three ways. The first and preferred technique is to graft the anhydride to the resin and then react the grafted anhydride with the hindered phenol and/or hindered amine antioxidant or stabilizer. The second is to copolymerize the anhydride with the olefin and again react the copolymerized anhydride with the antioxidant(s). The third technique is to first react the anhydride with the antioxidant(s) and then graft the reaction product to the polyolefin or copolymerize the reaction product with one or more olefins.

Examples of useful anhydrides containing unsaturation are maleic anhydride, itaconic anhydride, and nadic anhydride. The preferred anhydride is maleic anhydride. Excess anhydride, if present after reaction can be removed by

SUBSTITUTE SHEET devolatilization at temperatures in the range of about 200°C to about 250°C.

The grafted polyolefin can be prepared by simultaneously mixing and heating the polyolefin together with the anhydride, or the reaction product of anhydride and stabilizer, and an organic peroxide. Grafting temperatures can be in the range of about 100°C. to about 300°C. and are preferably in the range of about 150°C. to about 200°C. After grafting, the anhydride loses its unsaturation and becomes a succmic anhydride derivative.

For each 100 parts by weight of polyolefin, about 0.01 to about 10 parts by weight of anhydride, preferably about 0.1 to about 5 parts of anhydride, and about 0.01 to about 1 part by weight of organic peroxide, preferably about 0.05 to about 0.5 part of peroxide, can be used.

The organic peroxide used for grafting preferably has a decomposition temperature of 100° to 220°C. for a half-life of 10 minutes and is exemplified by the following compounds (the numbers set off by the parentheses are their decomposition temperatures (°C)): succmic acid peroxide (110), benzoyl peroxide (110), t-butyl peroxy-2-ethyl hexanoate (113), p-chlorobenzoyl peroxide (115), t-butyl peroxy isobutylate (115), t-butyl peroxy isopropyl carbonate (135), t-butyl peroxy laurate (140), 2,5-dimethyl- 2,5-di(benzoyl peroxy )hexane (140), t-butyl peroxy acetate (140), di-t- butyl diperoxy phthalate (140), t-butyl peroxy maleic acid (140), cyclohexanone peroxide (145), t-butyl peroxy benzoate (145), dicumyl peroxide (150), 2,5-dimethyl-2,5-di(t-butyl peroxy)hexane (155), t-butyl cumyl peroxide (155), t-butyl hydroperoxide (158), di-t-butyl peroxide (160), 2,5-dimethyl-2,5-di(t-butyl peroxy)hexane-3 (170), di- isopropyl benzene hydroperoxide (170), p-methane hydroperoxide (180), and 2,5-dimethyl hexane-2,5-di-hydroperoxide (213).

A typical procedure for grafting maleic anhydride onto polyethylene is described in United States patent 4,506,056.

SUBSTITUTE SHEET Grafting can also be accomplished by adding a solution of anhydride, an organic peroxide catalyst, and an organic solvent to a mixture of polyethylene or polypropylene in particulate form. The organic peroxide catalyst is soluble in the organic solvent. Various organic solvents, which are inert to the reaction, can be used. Examples of useful organic solvents are acetone, methyl ethyl ketone, methyl propyl ketone, 3-pentanone, and other ketones. Other carrier solvents which allow solubilization of peroxide and anhydride and which strip off well under appropriate devolatilization conditions may be used. Acetone is a preferred solvent because it acts as a stripping agent for residuals such as non-grafted anhydride or anhydride by-products.

The anhydride solution can contain about 10 to about 50 percent by weight anhydride; about 0.05 to about 5 percent by weight organic peroxide; and about 50 to about 90 percent by weight organic solvent based on the total weight of the solution. A preferred solution contains about 20 to about 40 percent anhydride; about 0.1 to about 2 percent peroxide; and about 60 to about 80 percent solvent.

The organic peroxides mentioned above or other conventional crosslinking agents can also be used to crosslink the polyolefins if desired.

The copolymer can be prepared by copolymerizing the olefin with the anhydride or the reaction product of anhydride and stabilizer in the presence of a radical polymerization initiator. Conventional processes of this type are discussed in Trivedi et al., Maleic Anhydride. Plenum Press, New York, 1982, pages 288, 289, 586, and 587.

One technique for preparing the copolymer involves contacting the comonomers in the gas phase in a tubular or, preferably, a tank reactor under a pressure of about 500 to about 4000 kilograms per square centimeter, preferably about 1000 to about 4000 kilograms per square centimeter, at a temperature of about 100

SUBSTITUTE SHEET to about 400°C, preferably about 150 to about 350°C, in the presence of a radical polymerization initiator and, if necessary, a chain transfer agent.

In the copolymerization, any one of the radical polymerization initiators and chain transfer agents conventionally used for the homopolymerization or copolymerization of ethylene or propylene can be used. Examples of the polymerization initiators are organic peroxides such as lauryl peroxide,dipropionyl peroxide, benzoyl peroxide, di-t-butyl peroxide, t-butyl hydroperoxide, and t- butyl peroxy-isobutyrate; molecular oxygen; and azo compounds such as azobisisobutyronitrile and azoisobutyrovaleronitrile. Examples of the chain transfer agents include hydrogen, paraffinic hydrocarbons such as methane, ethane, propane, butane, and pentane; alpha-olefins (such as butene-1 and hexene-1); aldehydes such as formaldehyde, acetaldehyde, and N-butylaldehyde; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; aromatic hydrocarbons; and chlorinated hydrocarbons.

Hydrocarbon cable filler grease is a mixture of hydrocarbon compounds, which is semisolid at use temperatures. It is known industrially as "cable filling compound". A typical requirement of cable filling compounds is that the grease have minimal leakage from the cut end of a cable at a 60°C or higher temperature rating. Another typical requirement is that the grease resist water leakage through a short length of cut cable when water pressure is applied at one end. Among other typical requirements are cost competitiveness; minimal detrimental effect on signal transmission; minimal detrimental effect on the physical characteristics of the polymeric insulation and cable sheathing materials; thermal and oxidative stability; and cable fabrication processability.

Cable fabrication can be accomplished by heating the cable filling compound to a temperature of approximately 100°C.

SUBSTITUTE SHEET This liquefies the filling compound so that it can be pumped into the multiconductor cable core to fully impregnate the interstices and eliminate all air space. Alternatively, thixo tropic cable filling compounds using shear induced flow can be processed at reduced temperatures in the same manner.

A cross section of a typical finished grease-filled cable transmission core is made up of about 52 percent insulated wire and about 48 percent interstices in terms of the area of the total cross section. Since the interstices are completely filled with cable filling compound, a filled cable core typically contains about 48 percent by volume of cable filler.

The cable filling compound or one or more of its hydrocarbon constituents enter the insulation through absorption from the interstices. Generally, the insulation absorbs about 3 to about 30 parts by weight of cable filler or one or more of its hydrocarbon constituents, in toto, based on 100 parts by weight of polyolefin. A typical absorption is in the range of about 5 to about 25 parts by weight per 100 parts by weight of polyolefin.

It will be appreciated by those skilled in the art that the combination of resin, cable filling compound constituents and antioxidant in the insulation is more difficult to stabilize than an insulating layer containing only resin and antioxidant, and no cable filling compound constituents.

Examples of hydrocarbon cable filler greases are petrolatum; petrolatum/polyolefin wax mixtures; oil modified thermoplastic rubber (ETPR or extended thermoplastic rubber); paraffin oil; naphthenic oil; mineral oil; the aforementioned oils thickened with a residual oil, petrolatum, or wax; polyethylene wax; mineral oil/rubber block copolymer mixture; lubricating grease; and various mixtures thereof, all of which meet industrial requirements similar to those typified above.

SUBSTITUTE SHEET Generally, cable filling compounds extract insulation antioxidants, as noted above, and are absorbed into the polymeric insulation. Since each cable filling compound contains several hydrocarbons, both the absorption and the extraction behavior are preferential toward the lower molecular weight hydrocarbon wax and oil constituents. It is found that the insulation composition with its antioxidant not only has to resist extraction, but has to provide sufficient stabilization (i) to mediate against the copper conductor, which is a potential catalyst for insulation oxidative degradation; (ii) to counter the effect of residuals of chemical blowing agents present in cellular and cellular/solid (foam/skin) polymeric foamed insulation; and (iii) to counter the effect of absorbed constituents from the cable filling compound.

Functionalized hindered phenols, useful in the invention, can be, among others, hydrazides, semicarbazides, oxamides, carbazates, or amino and amine compounds. The following are examples of the above: 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-aminopropane 2,6-di-t-butyl-4-aminophenol 2,6-di-t-amyl-4-aminophenol 2 ,6-di-t-hexyl-4-aminophenol 2,6-bis(l,l-dimethylpentyl)-4-aminophenol 2 ,6-bis( 1, 1,3 ,3-tetramethylbutyl)-4-aminophenol 2-t-butyl-6-t-amyl-4-aminophenol 2-t-butyl-6-( 1, l-dimethylbutyl)-4-aminophenol 2-t-amyl-6-(l,l-dimethylbutyl)-4-aminophenol 2-t-butyl-6-(l,l-dimethylpentyl)-4-aminophenol 2-t-butyl-6-(l,l,3,3-tetramethylbutyl)-4-aminophenol 2-t-butyl-6-methyl-4-aminophenol 2-t-amyl-6-methyl-4-aminophenol 3 ,5-di-t-butyl-4-hydroxybenzylamine 3,5-di-t-amyl-4-hydroxybenzylamine

SUBSTITUTE SHEET 3 , 5-di-t-hexyl-4-hydroxybenzylamine

3-t-butyl-5-methyl-4-hydroxybenzylamine

2-(3,5-di-t-butyl-4-hydroxyphenyl)ethylamine

2-(3,5-di-t-amyl-4-hydroxyphenyl)ethylamine

2-(3-t-butyl-5-methyl-4-hydroxyphenyl)ethylamine

3-(3,5-m-t-butyl-4-hydroxyphenyl)propylamine

3-(3,5-di-t-amyl-4-hydroxyphenyl)propylamine

3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propylamine

3-(3,5-di-t-butyl-4-hydroxyphenyl)propionhydrazide

3-(3,5-di-t-amyl-4-hydroxyphenyl)propionhydrazide

3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionhydrazide

3-(3-t-butyl-4-hydroxyphenyl)propionhydrazide

3-(3,6-m-t-hexyl-4-hydroxyphenyl)propionhydrazide

3,5-di-t-butyl-4-hydroxybenzhydrazide

3,5-di-t-amyl-4-hydroxybenzhydrazide

3-t-butyl-5-methyl-4-hydroxybenzhydrazide

3-(3,5-di-t-butyl-4-hydroxyphenyl)acrylic acid hydrazide

4-(3,5-di-t-butyl-5-hydroxyphenyl)semicarbazide l-methyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionhydrazide

(3,5-di-t-butyl-4-hydroxyphenyl)acetylhydrazide

N-(3,5-di-t-butyl-4-hydroxyphenyl)-N'-aminooxamide

2,5-di-t-butyl-4-hydroxyphenylcarbazate

3,5-di-t-butyl-4-hydroxybenzylcarbazate

(3,5-di-t-butyl-4-hydroxyphenylmercapto)acetylhydrazide

⁽3-t-butyl-5-methyl-4-hydroxyphenylmercapto)acetylhydrazide

3-(3,5-di-t-butyl-4-hydroxyphenylmercapto)propionhydrazide

3-(3-t-butyl-5-methyl-4-hydroxyphenylmercapto)propionhydrazide

(3,5-di-t-butyl-4-hydroxybenzylmercapto)acetylhydrazide

(3-t-butyl-5-methyl-4-hydroxybenzylmercapto)acetylhydrazide

3-( 3 ,5 -di-t-butyl-4-hydroxybenzylmercapto)propionhydrazide

3-(3-t-butyl-5-methyl-4-hydroxybenzylmercapto)propionhydrazide

SUBSTITUTE SHEET The preferred hindered phenol is 3-(3,5-di-tert-butyl-4- hydroxyphenyDpropionhydrazide.

Functionalized hindered amines, useful in the invention, can be, among others, piperidines functionalized with amines, hydrazines, hydrazides, carboxamides, oxamides, succinamides, or malonamides. The following are examples of the above:

4-amino-2,2,6,6-tetramethylpiperidine 4-amino-l-benzyl-2,2,6,6-tetramethylpiperidine 4-amino-l,2,2,6,6-pentamethylpiperidine 4-amino-l-(2-hydroxyethyl)-2,2,6,6-tetramethylpiperidine 4-amino-l-(2-cyanoethyl)-2,2,6,6-tetramethylpiperidine 4-amino-l-butyl-2,2,6,6-tetramethylpiperidine 4-aπ no-2,6-methyl-2,3,6-trimethylpiperidine 4-amino-2,6-diethyl-l,2,3,6-tetramethylpiperidine 2,2,6,6-tetramethyl-4-piperidinylhydrazine l,2,2,6,6-pentamethyl-4-piperidinylhydrazine 3-(2,2,6,6-tetramethyl-4-piperidinylamino)propionhydrazide (2,2,6,6-tetramethyl-4-piperidinylamino)acetylhydrazide 3-(l,2,2,6,6-pentamethyl-4-piperidinylamino)propionhydrazide N- (2 , 2 ,6 , 6-tetramethyl-4-piperidinyl)hydrazinecarboxamide N-(l,2,2,6,6-pentamethyl-4-piperidinyl)hydrazinecarboxamide N-(2,2,6,6-tetraιnethyl-4-piperidinyl)-N'-aminooxamide N-(2,2,6,6-tetramethyl-4-piperidinyl)-N'-aιmnosuccinamide N-(2,2,6,6-tetramethyl-4-piperidinyl)-N'-aminomalonamide N-(l-acetyl-2,2,6,6-tetraπιethyl-4-piperidinyl)-N'aminooxamide 3-(l-acetyl-2,2,6,6-tetramethyl-4-piperidinylamino)propion- hydrazide (2,2,6,6-tetramethyl-4-piperidinyloxy)acetyl hydrazide ( l,2,2,6,6-pentamethyl-4-piperidinyloxy)acetyl hydrazide 3-(2,2,6,6-tetramethyl-4-piperidinyloxy)propion hydrazide 3-( l,2,2,6,6-pentamethyl-4-piperidinyloxy)propion hydrazide

SUBSTITUTE SHEET N,N-bis-(2,2,6,6-tetramethyl-4-piperidinyl)-N'-aminooxamide 3-[N,N-bis(2,2,6,6-tetramethyl-4-piperidinyl)amino]- propionhydrazide N-(2,2,6,6-tetramethyl-4-piperidinyl)-N-butyl-N'aminooxamide

The preferred hindered amine is N-(2,2,6,6- tetramethyl-4-piperidinyl)-N'-aminooxamide.

The units bonded to the resin are the reaction product(s) of the bonded anhydride with the functionalized hindered amine and/or functionalized hindered phenol. These units can have the following generic formulas:

said units occurring in the polymer backbone, on grafted side chains, and/or as pendant units wherein x is 0 or 1;

Ri and R^ are independently methyl or hydrogen, and N-G is the residue of a primary amino or hydrazido substituted stabilizer group represented by either or both of the following formulas:

SUBSTITUTE SHEET

wherein R^ and R^ are independently tertiary alkyl groups of 4 or 5 carbon atoms, and

X' is a direct bond or -NH-,

-NH-C(=0)-(CH₂)_a-, or

-NH-C(=0)-(CH₂)_a-S-CH₂- wherein a = 0, 1 or 2 and the polymer is bound to the nitrogen;

(b)

wherein each B is independently methyl or ethyl, and Y is -(N(R⁶)C(=0)R⁷C(=0)-N(R⁶)- wherein each R° is independently hydrogen or methyl and R ' is a direct bond or a 1 to 4 carbon atom diradical.

SUBSTITUTE SHEET In formula (a), preferably, the hydroxy group is in the 4 position, and R^ and R^ are tertiary butyl and in the 3 and 5 positions.

In formula (b), preferably, R^ is hydrogen and R ' is a direct bond.

In the cable construction, for each 100 parts by weight of polyolefin, the following components are present in about the following proportions:

Parts bv Weight Component Broad Range Preferred Range

Anhydride 0.01 to 50 0.1 to 5

Hindered amine, 0.01 to 5 0.05 to 2.5 if present

Hindered phenol, 0.01 to 5 0.05 to 2.5 if present

Total hindered 0.01 to 5 0.05 to 2.5 amine and hindered phenol

Grease admixed 3 to 30 5 to 25 with polyolefin

The hindered phenols and hindered amines can be bonded to the same or different polyolefins, which can be blended. The bonded hindered phenol or amine can be present together with free hindered phenol or amine, and can also be used in combination with disulfides, phosphites or other non-phenolic or non-amine antioxidants in ratios of about 1:1 to about 1:2 for additional

SUBSTITUTE SHEET oxidative and thermalstability, but, of course, it must be determined to what extent these latter compounds are extracted by the grease since this could affect the efficacy of the combination.

The following conventional additives can be added in conventional amounts if desired: ultraviolet absorbers, antistatic agents, pigments, dyes, fillers, slip agents, fire retardants, stabilizers, crosslinking agents, halogen scavengers, smoke inhibitors, crosslinking boosters, processing aids, e.g., metal carboxylates, lubricants, plasticizers, viscosity control agents, and blowing agents such as azodicarbonamide. The fillers can include, among others, magnesium hydroxide and alumina trihydrate. As noted, other antioxidants and/or metal deactivators can also be used, but for these or any of the other additives, resistance to grease extraction must be considered. l,2-bis(3,5-di-tert-butyl-4-hydroxy- hydrocinnamoyl)hydrazine added as an adjunct metal deactivator and antioxidant is desirable.

Additional information concerning grease- filled cable can be found in Eoll, The Aging of Filled Cable with Cellular Insulation. International Wire & Cable Symposium Proceeding 1978, pages 156 to 170, and Mitchell et al, Development. Characteristics, and Performance of an Improved Cable Filling Compound. International Wire & Cable Symposium Proceeding 1980, pages 15 to 25. The latter publication shows a typical cable construction on page 16 and gives additional examples of cable filling compounds.

Additional examples of various polyolefins, hindered phenols, hindered amines, and anhydrides useful in the invention can be found in United States patents 4,801,749; 4,824,884; 4,857,596; 4,863,999; 4,866,136; 4,868,246; 4,874,803; and 4,927,891; and European patent application 434,080.

SUBSTITUTE SHEET The patents, patent application, and other publications mentioned in this specification are incorporated by reference herein.

The invention is illustrated by the following examples.

EXAMPLES 1 to 14

Various materials used in the examples are as follows:

Polyethylene I is a copolymer of ethylene and 1-hexene. The density is 0.946 gram per cubic centimeter and the melt index is 0.80 to 0.95 gram per 10 minutes.

Polyethylene II is a copolymer of ethylene and 1- hexene. The density is 0.95 gram per cubic centimeter and the melt index is 7.5 to 9.0 grams per 10 minutes.

Antioxidant A is tetrakis[methylene(3,5-di-tert-butyl-4- hydroxyhydrocinnamate)]methane.

Antioxidant B is l,2-bis(3,5-di-tert-butyl-4-hydroxy- hydrocinnamoyl)hydrazine.

Antioxidant C is N-(2,2,6,6-tetramethyl-4-piperidinyl)- N'aminooxamide .

Antioxidant D is 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic hydrazide.

Resin I is a copolymer of 1-octadecene and maleic anhydride in a 1 to 1 molar ratio. The molecular weight is 30,000 to 50,000. The particular copolymer is referred to in United States patent 4,857,596 together with references to conventional processes for the copolymerization of maleic anhydride and alpha-olefins.

In a Brabender™ mixer, polyethylene II is mixed and melted with maleic anhydride and dicumyl peroxide (added as 40 weight percent peroxide on clay). After fluxing, the temperature of the mixture is raised to 185°C and held at that temperature for three minutes before discharging and grinding. A sample is extracted with acetonitrile to remove any unreacted anhydride and the

SUBSTITUTE SHEET percent grafted anhydride is determined using Fourier transform infrared analysis (FTIR).

A Brabender™ mixer is charged with maleic anhydride grafted polyethylene II, prepared as above, containing sufficient anhydride to react completely with antioxidant. Antioxidants C or D or mixtures of C and D are added in weighed quantities and the blend is fluxed and heated to 220°C for 5 minutes, and then held at the temperature for an additional 5 minutes to complete the reaction. The resultant polymer bound antioxidant products are pelletized for use as a masterbatch.

A laboratory procedure simulating the grease filled cable application is used to demonstrate performance. The polyethylene pellets are formed into approximately 10 mil (0.010 inch) thick test plaques using ASTM D-1928 methods as a guideline. There is a final melt mixing on a two roll mill or laboratory Brabender™ type mixer followed by preparation of the test plaques using a compression molding press at 150°C. Initial oxygen induction time is measured on these test plaques.

A supply of hydrocarbon cable filler grease is heated to about 80°C and well mixed to ensure uniformity. A supply of 30 millimeter dram vials are then each filled to approximately 25 millimeters with the cable filler grease. These vials are then cooled to room temperature for subsequent use. An oil extended thermoplastic rubber (ETPR) type cable filler grease is the hydrocarbon cable filler grease used in these examples. It is a typical cable filling compound.

Each ten mil test plaque is then cut to provide about twenty approximately one-half inch square test specimens. Before testing, each vial is reheated to about 70°C to allow for the easy insertion of the test specimens. The specimens are inserted into the vial one at a time together with careful wetting of all surfaces with the cable filler grease. After all of the specimens have been

SUBSTITUTE SHEET inserted, the vials are loosely capped and placed in a 70°C circulating air oven. Specimens are removed after 2 and 4 weeks, the surfaces are wiped dry with tissue, and the specimens are tested for OIT. After 4 weeks, the remaining specimens are removed, wiped dry, and placed in a static air chamber at 90°C. At various intervals, specimens are removed and tested for OIT.

OIT testing is accomplished in a differential scanning calorimeter with an OIT test cell. The test conditions are: uncrimped aluminum pan; no screen; heat up to 200°C under nitrogen, followed by a switch to a 50 milliliter flow of oxygen. Oxidation induction time (OIT) is the time interval between the start of oxygen flow and the exothermic decomposition of the test specimen. OIT is reported in minutes; the greater the number of minutes, the better the OIT. OIT is used as a measure of the oxidative stability of a sample as it proceeds through the cable filler grease exposure and the oxidative aging program. Relative performance in the grease filled cable applications can be predicted by comparing initial sample OIT to OIT values after 70°C cable filled grease exposure and 90°C oxidative aging.

Variables and results are set forth in the following Table.

SUBSTITUTE SHEET TABLE

EXAMPLE 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Formulation (% by wt):

CΛ

Polyethylene I 99.56 99.80 99.45 99.56 90 99.80 99.25 89.80 99.00 99.85 89.85 89.85 89.85 90.0

S3 Antioxidant A 0.44 - 0.40 - - - - - - - - - - -

0.20 0.20 0.20 0.15 0.15 0.15 0.15 0.15 m

CO - - - 0.55 - 0.33 σ

ID 0.44

10(i) - - 10(ii) - - lθ(iii) 10(iv) 10(v) 10(vi)

0.52 - - - - -

TABLE (contd.)

4 weeks 8 weeks 12 weeks

CD 16 weeks

9 20 weeks

c

H m N> co m m

Notes to Table:

(i) Polyethylene II is grafted with 1.3 percent by weight maleic anhydride based on the weight of the polymer. The polymer is bonded to 4 percent by weight antioxidant D based on the weight of the polymer. The amount of masterbatch is sufficient to provide 0.4 percent by weight antioxidant D to polyethylene I based on the weight of the polymer.

(ii) Polyethylene II is grafted with 0.5 percent by weight maleic anhydride based on the weight of the polymer. The polymer is bonded to 1.25 percent by weight antioxidant C based on the weight of the polymer. The amount of masterbatch is sufficient to provide 0.125 percent by weight antioxidant C to polyethylene I based on the weight of the polymer.

In example 9, the resins and antioxidants are compounded at 220°C for five minutes, pelletized, and then prepared for OIT testing.

(iii) Polyethylene II is grafted with 0.9 percent by weight maleic anhydride based on the weight of the polymer. The polymer is bonded to 1.38 percent by weight antioxidant D and 1.65 percent by weight antioxidant C based on the weight of the polymer. The two antioxidants are mixed with the grafted polyethylene II, heated for 5 minutes at 220°C, and held for 5 minutes at 220°C.

(iv) The procedure of (iii) is repeated except that antioxidant C is first mixed with grafted polyethylene II and heated to 220°C for 5 minutes and then antioxidant D is added, mixed, and heated to 220°C for 5 minutes.

(v) The procedure of (iv) is repeated except that antioxidant D is first mixed with grafted polyethylene II and heated to 220°C for 5 minutes and then antioxidant C is added, mixed, and heated to 220°C for 5 minutes.

SUBSTITUTE SHEET (vi) The procedure of (iii) is repeated except that antioxidant D is used in an amount of 1.65 percent by weight and antioxidant C is used in an amount of 1.38 percent by weight.

In (iii), (iv), (v), and (vi), the total amount of antioxidants is sufficient to provide 0.40 percent by weight antioxidants based on the weight of polyethylene I.

SUBSTITUTE SHEET

Claims

1. An article of manufacture comprising (i) a plurality of electrical conductors, each surrounded by one or more layers comprising one or more polyolefins having bonded thereto, through an anhydride of an aliphatic diacid, one or more functionalized hindered amines and/or functionalized hindered phenols and (ii) hydrocarbon cable filler grease within the interstices between the surrounded conductors.

2. The article of manufacture defined in claim 1 wherein the reaction product(s) of the bonded anhydride with the amine and/or phenol have the following formula:

said reaction product(s) occurring in the polymer backbone, on grafted side chains, and/or as pendant units wherein x is 0 or 1;

R and Br are independently methyl or hydrogen, and N-G is the residue of a primary amino or hydrazido substituted stabilizer group represented by either or both of the following formulas:

SUBSTITUTE SHEET (a)

X' is a direct bond or -NH-,

-NH-C(=0)-(CH₂)_a-, or

-NH-C(=0 )-(CH₂)_a-S-CH₂- wherein a = 0, 1 or 2 and the polymer is bound to the nitrogen; and

(b)

wherein each R^ is independently methyl or ethyl, and Y is -(N(R⁶)C(=0)R⁷C(=0)-N(R⁶)- wherein each R° is independently hydrogen or methyl and R ' is a direct bond or a 1 to 4 carbon atom diradical.

SUBSTITUTE SHEET

3. The article of manufacture defined in claim 2 wherein, in formula (a), the hydroxy group is in the 4 position, and R^ and R are tertiary butyl and in the 3 and 5 positions.

4. The article of manufacture defined in claim 2 wherein, in formula (b), R" is hydrogen and R ' is a direct bond.

5. The article of manufacture defined in claim 2 wherein the hydrocarbon cable filler grease or one or more of the hydrocarbon constituents thereof is present in the layer(s) of component (i).

6. The article of manufacture defined in claim 5 wherein the total amount of hydrocarbon cable filler grease or one or more of the hydrocarbon constituents thereof present in the layer(s) of component (i) is in the range of about 3 to about 30 parts by weight based on 100 parts by weight of polyolefin.

7. An article of manufacture comprising one or more electrical conductors, each surrounded by one or more layers of a mixture comprising

(a) one or more polyolefins having bonded thereto reaction product(s) having the following formula:

SUBSTITUTE SHEET said reaction product(s) occurring in the polymer backbone, on grafted side chains, and/or as pendant units wherein x is 0 or 1;

Ri and R^ are independently methyl or hydrogen, and

N-G is the residue of a primary amino or hydrazido substituted stabilizer group represented by either or both of the following formulas:

X' is a direct bond or -NH-, -NH-C(=0)-(CH₂)_a-, or

-NH-C(=0)-(CH₂)_a-S-CH₂- wherein a = 0, 1 or 2 and the polymer is bound to the nitrogen; and

SUBSTITUTE SHEET wherein each R^ is independently methyl or ethyl, and Y is -N(R⁶)C(=0)R⁷C(=0)-N(R⁶)- wherein each R^ is independently hydrogen or methyl and R ' is a direct bond or a 1 to 4 carbon atom diradical;

and

(b) a hydrocarbon cable filler grease or one or more of the hydrocarbon constituents thereof.

8. The article of manufacture defined in claim 7 wherein, in formula (a), the hydroxy group is in the 4 position, and R and R are tertiary butyl and in the 3 and 5 positions and, in formula (b), R" is hydrogen and R' is a direct bond.

9. An article of manufacture comprising (i) a plurality of electrical conductors, each surrounded by one or more layers comprising polyethylene, polypropylene, or mixtures thereof having bonded thereto, through maleic anhydride, N-(2,2,6,6- tetraniethyl-4-piperidinyl)-N'-aminooxamide and/or 3-(3,5-di-tert- butyl-4-hydroxyphenyl) propionic hydrazide and (ii) hydrocarbon cable filler grease within the interstices between the surrounded conductors wherein the total hindered amine and hindered phenol is about 0.01 to about 5 parts by weight and the maleic anhydride is about 0.01 to about 10 parts by weight, all based on 100 parts by weight of polyethylene or polypropylene.

10. The article of manufacture defined in claim 9 wherein 1,2-bis (3-5-di-tert-butyl-4-hydroxy-hydrocinnamoyl)- hydrazine is included in the layer(s) as an unbound constituent.

SUBSTITUTE SHEET