US2079943A

US2079943A - Insulated electrical conductor

Info

Publication number: US2079943A
Authority: US
Inventors: Lobdell George Spencer
Original assignee: General Cable Corp
Current assignee: General Cable Corp
Priority date: 1932-10-26
Filing date: 1932-10-26
Publication date: 1937-05-11
Anticipated expiration: 1954-05-11

Description

May 11, 1937. G. s. OBDELL 2,079,943

I `INSULATED ELECTRICAL CONDUCTOR Original Filed Oct. 26, 1932 ATTORNEY` Patented May 11, 1937 l 2,079,943

INSULATED ELECTRICAL CONDUCTOR George Spencer Lobdell, Rome, N. Y., assig'nor to General Cable Corporation, New York, N. Y., a V corporation of New Jersey Application October 26, 1932, Serial No. 639,594

Renewed June 1, 1936 16 Claims. (Cl. 173-264) This invention relates to insulated electrical In chemical plants, rubber-insulated wires and conductors. It is an object of the invention to cables must be replaced at short intervals beprovide improved insulated conductors. Other cause of the injurious effects of acids and alkalis objects and advantages of the invention will on the rubber. The problem in chemical plants appear hereinafter. is of such moment that wherever possible bare 5` An illustrativeembodiment of the invention conductors are being substituted for insulated selected merely for descriptive purposes is shown conductors because of the short life of rubber in th'e accompanying drawing, in which: and other known insulating materials.

Fig. 1 is an enlarged longitudinal elevation of This plastic substance has a further important 10 4a section of insulated conductor with the insu-V advantageover rubber as an electrical insulating 10 lating layers removed progressively greater dismaterial for the reason that this plastic subtances to disclose the construction; D stance is very highly resistant to injuryvby the Fig.-2 is a section through the conductor o effects of electrical corona. In rubber-insulated Fig. 1 substantially on the line 2 2; conductors used at medium or high voltages, par- Fig. 3 is an enlarged longitudinal elevation of ticularly if the rubber is also under physical stress l5 Vanother se'ction of insulated conductor with the s uch as is caused by bending the conductors, the insulating layers removed progressively greater o'zone which is formed by the corona cuts and distances to disclose the construction; and destroys the rubber. Experimental tests have Fig. 4 is a section through the conductor of shown that this plastic substance is substantially f Fig. 3 substantially on the line 4 4. unaffected by corona, and that for the same 20 This application is a continuation in part of thickness of insulation it may be used at high my application Serial No. 619,410, filed June 27, voltages and under physical conditions which 1932. are prohibitive for rubber.

The plastic substance disclosed in Canadian When used for insulating electrical conduc- Letters Patent No. 290,645, June 18, 1929, to Jotors, these olen polysulfide reaction products 25 a seph C. Patrick, consists mainly of organically desirably are mixed with fillers and curing agents combined sulfur. This plastic substance may be in somewhat the same manner as rubber. 'I'he formed by the interaction of halogen additive comterm "olefin polysulfide reaction products is used pounds of olefins with polysuliides, for example. herein to include such mixtures in the same sense by the interaction of ethylene dichloride and sothat .irubber is used as a broad term to include 30 dium polysulde, and merelyk for convenience in mixtures of pure rubber with fillers and curing description may be described as an olen polysulagents. dereaction product, and inthe exemplary case g Olefin polysulfide reaction products may be as a condensation product of ethylene dichloride cured by heating in a manner somewhat similar and an alkali pOlySlllde- ThiSySllbStanCe, WhiCh to that used in curing rubber, as by the open -is a'combinationof carbon, hydrogen and sulfur, steam process, but when so cured the resultant has ,certain physical properties resembling those substance is very SpOngy and porous. Although of rubber. 'I'he hardness of this substance may olefin polysulflde reaction products are cured by Vary OVel a Wide fange, dependent 0n the Sulfur heating, the word cured has an entirely differ- 40 COD'Ilt, flOm a hard DlOdllCi? t0 a Soft elastic ent significance than when used with reference 40 those of rubber in a number of important reoften is desirable that the insulation of electrical product. For the insulation of flexible electrical to rubber, 1u the case of fumery buying comconductors the sulfur content desirably is about prises the combination of the rubber with sulfur .82% t0 33%- whereas inthe case of olefin polysulde reaction The Properties 0f thls substance infer from products, curing comprises the production ofa stable chemical compound from an unstable form 45` of the same compound. Cured olefin polysulde reaction products loaded suciently to.'reduce porosity have a low resistance to fatigue and crack rather easily, and the dielectric qualities 50 conductor@ be immune to attack by oils, acids, are not satisfactory for use in insulatingelectrical alkalis and organic solvents. For example, rub- Conductors. During the Curlng 0f Olen polyslllber-insulated ignition wire used in internal comfide reaction products by theheat process a .disbustion engines deteriorates rapidly because of agreeable gaseous decomposition product .is given spects. This plastic substance is highly resistant to decomposition by oils, acids and alkalis, and is substantially insoluble in practically all known acids, alkalis and organic solvents. It

the oil which comes in contact with the rubber. off having the characteristics of tear gas. The 55 formation of this gas makes the handling and curing of the substance more diiilcult.

The diiculties encountered in curing olen polysuliide reaction products may bepartially overcome by the addition of rubber. It has been found that the addition of very small quantities of rubber does not seriously affect the resistance of the resulting mixture to oils, acids, alkalis, and organic solvents. However, if rubber is added in sufficient quantities to materially reduce the porosity and sponginess of the cured product, the resistance to oil and to the effects of electrical corona are greatly reduced.

It is believed that the objectionable porosity and sponginess in the cured olen polysulde reaction products is caused by the formation of the gaseous decomposition product, probably a thio-aldehyde, in the substance during the heating process. Other substances may be added to accelerate the curing of the oleiin polysulde reaction products, but in the manufacture of insulated wires it is impractical to use an accelerator sufficiently rapid to eect complete curing of the substance before gas is formed in any substantial quantity. The reason for this is that.

the use of such a rapid accelerator would result in the precuring of the substance on the rolls and in the extruding machines before the substance is on the wire. Furthermore, such a rapid accelerator would result in any rubber in the mixture being overcured.

Applicant has found that olefin polysulfide reaction products may be heat treated to give a substantially non-porous product by adding to the compound before heating another substance which substantially prevents the formation of free gas in the compound. It is believed that this -added substance combines with the gaseous decomposition product to form a condensation product with a low vapor pressure, thereby substantially preventing the formation of pores and holes in the compounds. Such substances are found in the classes of primary aromatic amines, naphthylamines, naphthols and phenols, and contain the group NH2 or the group OH combined with radicals which so limit the activity of these groups as to cause the prevention of gas formation to take place under .curing conditions. In this use the chemical activity of the individual members of these classes varies, and therefore the most effective member of these series of compounds is determined by the conditions of curing the oleiin polysulfide reaction products. For

example, applicant has found that a small amount of orthotoluidine incorporated inl` an olen polysulde reaction product before" curing permits curing in a solid, non-porous compound in open steam. One suitable mixture for a cure of fty minutes at 287 F. is as follows:

This compound has excellent electrical properties and exhibits a high resistance to oils, acids, alkalis and organic solvents. b

If the electrical properties are not of primary importance, as where the compound is to be used as a sheath enclosing an insulated conductor, a different mixture may be preferable. In such a compound it is desirable that the resistance to oils, acids, alkalis land organic solvents be a maximum. One suitable mixture for a cure of 50 minutes at 287 F. is as follows: Olen polysulde reaction product gm 500 Smoked 'sheets gm..- 50 Diphenyl-guanidine gm 4.5 Orthotoluidine c'.c 5 Zinc oxide gm 50 Talc gm-.. Stearic acid gm-- 5 Phenyl beta naphthylamine gmg- 5 vCarbon black gm-- 50 Sulfur gm-- 5 For somewhat softer cured compounds applicant has found that beta-naphthylamine is suitable for preventing porosity, while for still softer stock, beta-naphthol may be used in lieu of orthotoluidine. Olen polysulde reaction products cured in accordance with this invention have characteristics which make vthem highly desirable as coverings for electrical conductors. The cured product is flexible and elastic, and resembles rubber in these respects. The cured product is rm and substantially non-porous. `The product retains its high resistance to oil and chemicals, and also to the effect of corona discharge. The substance may be milled and handled in much the same manner as rubber, and the formation of the objectionable gas during such handling is largely avoided. This plastic substance and the method of curing are disclosed and claimed in my copending application Serial No; 639,733, filed October 26, 1932.

Plastics made in accordance with this invention may be used as insulation on single or multiple strand conductors, and may be applied in substantially the same manner as rubber, for example by extruding. If desired, the olefin polysulfide plastic may replace rubber and comprise the entire electrical insulation for'the conductor. However, it may be desirable to cover the conductor with a sheath of rubber only slightly thinner than the normal thickness of rubber insulation, and then apply a continuous thin protective wall of olefin polysulde plastic over the rubber insulation. In such a construction the rubber is effectively protected by the olen polysulfide reaction product wall against oils and acids, as well as against ozone which may be formed by corona discharge. It will be apparent that suitablejackets or armorings, for example wrappings of cloth tape, may be applied over the insulating jacket Ain the same manner as is done at present with rubber insulated conductors.

Referring to Figs. l and 2 there is shown merely by way of illustration a multiple strand conductor I0 enclosed in a sheath Il of olefin polysulde reaction product over which is a wrapping l2 of cloth tape. A modified construction is shown in Figs. 3 and 4 in which a conductor 20 is enclosed in a sheath 2l of rubber over which is a relatively thin wall 22 of olen polysulde reaction product and a spirally Wrapped cloth tape 23.

The foregoing description of certain speciflc embodiments of the invention is illustrative merely, and is not intended as defining the limits of the invention.

I claim:-

l. An insulated electrical conductor comprising in combination a conductor, a sheath of rubber, and a relatively thinner outer sheath o f substantially non-porous'oleiin polysulde reaction product which has been heat treated in the presence of avgas formation retarding substance selected from the classes of aromatic amines, napthol and phenols containing respectively the group NH2 and the group OH combined with radicals which so limit the activity of the groups as to cause the reduction of gas formation in the product under curing conditions 2. An insulated electrical conductor comprising in combination a conductor, a sheath of rubber, and a relatively thinner outer sheath of substantially non-porous olen polysulde reaction product which has been heat treated in the presence of a primary amine substance capable of combining with a gaseous product formed in the olefin polysulfide reaction product during heating to yield a condensation product.

3. An insulated electrical conductor comprising in combination a conductor, and a sheath of a substantially non-porous plastic olefin polysulde reaction product which has been heat treated in the presence of orthotoluidine.

4. An insulated electrical conductor comprising in combination a conductor, and a sheath of a substantially non-porous plastic olefin polysulde reaction product which has been heat treated in the presence of beta-naphthylamine.

5. An insulated electrical conductor comprising in combination a conductor, and a sheath of a substantially non-porous plastic olefin polysulfide reaction product which has been heat treated in the presence of beta-naphthol.

6. An insulated electrical conductor comprising in combination a conductor, and a sheath of substantially non-porous olefin polysulfide reaction product which has been heat treated in the presence of a primary amine substance capable of combining with a. gaseous product formed in the olefin polysulde reaction product during heating to yield a condensation product.

7. An insulated electrical conductor comprising in combination a conductor, and a sheath of substantially non-porous condensation product of ethylene dichloride and an alkali polysulflde which has been heat-treated in the presence of a primary amine compound having the property of 'preventing or retarding the formation of gas in said condensation product.

8. An insulated electrical conductor comprising in combination, a conductor, a sheath of rubber, and a relatively thinner outer sheath of substantially non-porous olefin polysulfide lreaction product which has been heat treated in the presence of orthotoluidine.

/ 9. An insulated electrical conductor comprising in combination a conductor, and a sheath of a substantially non-porous plastic olefin polysulide reaction product which has been heat treated in the presence of a napthol compound which contains the group OH combined with radicals which so limit the activity of this group as to cause the prevention of gas formation to take place under curing conditions.

10. An insulated electrical conductor comprising in combination a conductor, and a sheath of a substantially non-porous plastic olen polysulfide reaction product which has been heat treated in the presence of an amino-base compound which contains the group NH2 combined with radicals which so limit the activity of this group as to cause the prevention of gas formation to take place. under curing conditions.

11. An insulated electrical conductor comprising in combination, a conductor, a sheath of rubber, and a relatively thin outer sheath of substantially non-porous olefin polysulfide reaction product Which has been heat treated in the presence of beta-naphthylamine.

12. An insulated electrical conductor comprising in combination, a conductor, a sheath of rubber, and a relatively thin outer sheath of substantially non-porous olen polysulde reaction product which has been heat treated in the presence of beta-naphthol.

13. An insulated electrical conductor comprising in combination, a conductor, and a sheath of a substantially non-porous, plastic olen polysulflde reaction product which has been heat treated in the presence of a mono-amino derivative of an aromatic hydrocarbon of a hexacarbocyclic ring on to which is substituted an alkyl group in the ortho position.

14. An insulated electrical conductor comprising in combination, a conductor, anda sheath of substantially non-porous olen polysulfide reaction product which has been heat treated in the presence of a primary amine compound having the property of preventing or retarding the formation of gas in said olen polysulde reaction product.

15. An insulated electrical conductor comprising in combination a conductor, and a sheath of substantially non-porous olen polysulde reaction product which has been heat treated in the presence of a substance from the group consisting of orthotoluidine, beta-naphthylamine and betanaphthol.

16. An insulated electrical conductor comprising in combination a conductor, and a sheath of a substantially non-porous plastic olen polysulflde reaction product which has been heat treated in the presence of a phenol compound which contains the group OH combined with radicals which so limit the activity .of this group as to cause the prevention of gas formation to take place under curing conditions.

' GEORGE SPENCER LOBDELL.