US2391931A - Method of manufacturing electrical conductors having a knitted protective jacket - Google Patents

Description

Jan. 1, 1946. M. D. SWARTZ ETAL 2,391,931

METHOD OF MANUFACTURING ELECTRICAL CONDUCTORS HAVING KNITTED PROTECTIVE JACKETS Filed April 4, 1942 INSUZ 4 TING SHEA THING 3 BEA/0E0 .14 CKET WITH 1 1 WIAT/IEE PEOOF/NG ASPHALT IMPEEGNA TIO/V my TING I l v Patented Jan. 1, 1 946 UNITED vSTATES PATENT OFFICE i ME'rnon or MANUFACTURING uaCrmCar.

CONDUCTORS HAVING A KNITTED rno- TECTIVE JACKET Application April 4, 1942, Serial No. 437.676

7 Claims.

The present invention relates primarily to improvements in insulated conductors provided with an insulating covering, the conductor core also carrying a loosely knitted tubular fibrous jacket or sheath, this being in contradistinction to prior art conductor cores which are provided with jackets which are tightly and securely braided around the conductor core.

The substitution of a knitted fibrous jacket, and particularly of the character herein disclosed, for a tightly braided jacket has made it necessary to provide a special saturant for the tubular knitted jacket, said saturant functioning to adequately bond the tubular knitted fabric sheath to the insulating medium of the conductor core and further to bond threads of the fibrous sheath one to the other so that upon the bending or flexing of the electrical conductor, the insulating covering is not exposed to the air or to a deteriorating amospheric influence. The saturant composition is applied in a liquid state to the tubular knitted fibrous sheath and cools to a soft pliable adhesive condition.

treated, it may be further processed to apply a dame proofing coating of stearine pitch and then a color coating, all as well known in the prior art.

It is the primary object or" the present inveu tion to provide a method of manufacturing an electrical conductor having a conductor Wire, and insulating jacket thereon, and thereover a tubular knitted protective jacket, said method comprising heating a saturant to substantially remove therefrom all'volatile matter, impregnating the knitted jacket with the so -treated saturant and adhesively uniting the knitted jacket to the in-= sulated jacket while adhesively uniting the threads of the knitted jacket together so that upon subjecting the so-treated conductor to substantial stresses, the insulating jacket is not exposed to deteriorating atmospheric conditions, said saturant being preferably a plastic resin saturant and, in some cases, having in admixture therewith a thermoplastic cellulose ether com patible with the resin.

It is a further object of the present invention to maintain the saturant or adhesive during the impregnating step at a temperature varying between about l80 F. and about 350 F. The invention will be illustrated in connection with the accompanying drawing, in which: I

' Figure 1 is a plan view showing a conductor provided with a prior art braided jacket, the latter being impregnated with an asphalt water proofing composition.

Figure 2 is a diagrammatic representation of the saturating, finishing and polishing apparatus.

Figure 3 is a perspective elevation oi a device Bill After the conductor core has been so did in which electric conductors made in accordance with the present invention may be coated with a color coating composition and thereafter dried.

Fisure i is a. plan view illustrating in detail the structure of a tubular braided jacket.

Figure 5 is an enlarged view of a conductor provided with a knitted jacket formed of a group of interconnected wales extending spirally around the insulating sheath.

' Figure 6. is a detail showing the applicator pot.

Reierring to Fig. 1, the copper wire, identified by the latter A, carries an insulating sheathing B which is preferably rubber, but which may be any material that will insulate the copper wire. Thi conductor core is Provided with a braided jacket C which is impregnated with the usual water proofing saturant or compound D, an asphalt composition being normally used for this purpose. After the tubular braided jacket has been treated with the saturant, there is then usually applied a coating E of a flame retarding and weather proofing material, said coating preferably being stearine pitch or a mixture of stearine pitch and other elements, as well known in the prior art. it is quite customary to cover the stearine pitch coating E with a color coating F. Thereafter, if desired. there is applied over the color coating F, a wax-like coating G1.

An electrical conductor produced as above set forth and using a tubular braided fabric jacket has proved satisfactory when united to the insulating coating of the conductor core by means of an asphalt water proofing saturant. Recently, however, instead of manufacturing the electrical conductor with a braided jacket, it has been mam uiactured with a knitted loosely woven tubular threaded fabric jacket. The use of a knitted jacket, and particularly of th character herein set forth, has certain advantages; namely, rapid production and lower cost. One knitting machine can do the work of from six to ten braiding ma chines, and therefore from the standpoint of production capacity, the production of electrical conductors with knitted jacket is highly advantageous. Further, the use of the knitted jacket, and particularly of the character herein set forth, enables cotton of lower tensile strength to be used than has hitherto been used in the production of braided tubular protective fibrous jackets. However, the use of the knitted jacket has presented quite a problem in that on flexing, bending and twisting of the conductor carrying said knitted jacket, said jacket being impregnated with the prior art asphalt saturating composition, the threads of the knitted jacket did not adhere one to the other and did not adhere sufiiciently to the insulating rubber sheath, which ww just below the jacket, to prevent said rubber sheath from being exposed to the action of the atmosphere, therebycausing rapid deterioration of the rubber insulating medium of the conductor core and impairment of the insulating properties of the con doctor. The apparatus used in saturating the knitted jacket of the conductor core of the present invention and in applying the flame proofing stearine pitch and the subsequent color coating composition is shown inFig. 2. The electrical conductor is provided with a naturallyoccurring or synthetic vulcanized rubber insulating covering 28 and a tubular jacket 28, as shown inFig. 5. This electrical conductor is passed through the saturant 6 present in tank 2', the saturant me= dium in said tank being preferably maintained in the tankat a temperature of about 300 F al through this saturant liquid may vary in temperature between 180 to 350i" El, depending upon the specific composition of the saturant. The excess saturant medium is removed from the knitted fabric jacket by means of squeezing rolls 2. There is then applied to the saturated knitted jacket a finishing coating which may be of any suitable character but which is preferably a flame proofing and a weather proofing coating, as typifled by the prior art coatings of this character, and particularly stearine pitch. The latter is applied by means of a wheel is. rotating in a bath of stearine pitch present in the vessel said stearine pitch being preferably heated to 366 F. The amount of stearine pitch which is applied to the conductor is regulated by the size of the open ing between the rolls to and While the thickness of the stearine pitch coating may vary considerably depending on circumstances, it is usually between i to 1 thousandths of an inch thick. It may be somewhat greater or even somewhat less. Taicor an equivalent medium is then applied to the fairly hot stearine pitch coating from the corn tainer do, said talc serving to diminish the tend: ency of the conductor core to stick to itself when it is wound on the 'reel it. The stearine coated conductor core to which the talc has been applied is then passed through a polishing device ed aromas vary, the conductor core is preferably passed through these baths at a rate varying between 200 to 350 feet per minute. The speed of travel is not critical.

The color coating composition is applied to the conductor in the coating and drying apparatus shown in Fig. 3, said apparatus comprising an applicator pot 5 suitably located in a tower 6, said applicator not being provided with a partition l whereby there is formed a compartment 5 adapted to contain the color coating composition .3 and a wax coating compartment adapted to contain a waxing material it. Suitable upper and lower guide rolls it and liars provided, the wire it passing from the pay-off reel it under guide roll it and through the coating solution 3 present in the applicator pct t. The wire passes through the coating composition t, through the wiping gasket it, around the upper roll it, then back and down around the lower roll it; then through the coating composition t a second time; and, if

necessary, through the coating composition a thirdtime. Thereafter, the coated and dried wire passes through the waxing compartment it and then to the re-wind reel El. The tower id is pref: erably, although not necessarily, an air conditioned chamber. That is, th chamber may be controlled from the standpoint of temperature and from the standpoint of humidity.

The differences in structure between a braided jacket and a knitted tubular jacket will be clearly understood from a consideration of Figs. 4. and 5. Referring to Fig. 4, the copper or aluminum wire it carries the rubber insulating covering it, and the latter is provided with a tubular braided jacket 25. It is to be noted that the thread 22, a thread of the right to the left course, passing around the conductor core, passes under the thread 23 and over the thread of the left to for the purpose of smoothing and cylindrically,

shaping the conductor core to its final form prior to the application of the color coating. The

polishing device is generally water cooled by means of ordinary city water so that the coatings of the conductor may be, chilled and solidified at this stage of manufacture. Normally, the saturant tank 2 contains about 1000 pounds of saturant, and since the saturating step and the entire process is preferably a continuous one, the saturant tank is continuously replenished with melted saturant from a preheating tank which is preferably maintained at or about-the temperature of the satl ll'ullil in the saturant tank. One of th functions of the preheating tank is to drive ofi from the saturant before the latter is applied to the knitted jacket, all of the volatile matter that can be driven 0d at a temperature in the neighborhood of 250 to 350 or 400 F. t

It is to be noted that no volatile medium or solveut is present in the saturant composition. It a volatile solvent were present, such as naphtha, benzol, alcohol, or the like, it would be necessary 7 to allow the volatile solvent to evaporate from the saturated knitted jacket before the saturant could assumeits final soft and pliable state. This would prohibit rapid manufacture since considerable time would have to elapse between the application of the saturant composition to the knitted tubular jacket, and the application of the finishing coat and its subsequent polishing. While the speed of travel of the conductor core through the saturant bath and the finishing. bath may the right course, and under thread 25. Thread it of the right to the left course passes over thread it, under thread 2t, and over thread The threads of one course may pass over one thread of the opposite course, under two threads, then over one thread, and then under two threads. There may be other variations of this over and under structure, but in any case, it is necessary for the threads to pass completely around the conductor core. Since a braided structure of this type sets comparatively tightly on the'rubber covered wire, the conductor and the conductor core maybe bent and flexed without the braided jacket being so displaced as to permit the exposure of the rubber when, as has been customary, the tubular braided jacket is impregnated with an asphalt saturating solution, then covered with a flame proofing stearine pitch, color coated, and waxed to produce the well known insulated conductor of the prior art.

Referring to Fig. 5, the wire 27 is provided with a rubber or prior art equivalent insulating covering 2d, the latter being provided with a knitted jacket 29 which is formed of a group of interconnected wales :iii and ti which extend spirally around the wire 2'5 and'the insulated covering 28 of the conductor core. The courses 32, 33, 3%. 35, 38 and 37 extend longitudinally of the conductor core. In such and similar knitted jackets, the knitting structure being capable of considerable variation so long as the tubular knitted structure is formed of wales extending'spirally around the conductor core, the successive threads of the wales having interconnected loops. Each thread, instead of being wrapped around the conductor core, is laid along it with a loop around to the next thread or a second adjoining thread.

However, since the threads are not wrapped around the conductor and are not bound under or tightly tied to each other, the entire knitted structure is a relatively loose one, and when the conductor is bent or flexed, the insulating cover of the conductor core, as for example, rubber. pushes through the jacket and is exposed. Stated differently, the fibrous jacket of the prior art was braided, woven or wrapped around the conductor, and each thread of'the Jacket encircled the conductor. The fibrous jacket of the present invention is a knitted jacket comprising interknitted courses of loops, the separate threads being laid along the conductor and not encircling the conductor. The pattern of this knit is subject to wide variation depending upon the number of thread supplies, the number of needles, the dispositionof the needles in the knitting machine, and the like, and nothing in this disclosure is intended to limit the invention to any one pattern of knitting. for the invention serves equally :well with any pattern of knitted fibrous jacket.

However, it is desired to point out that the present invention is particularly suitable for the treatment of knitted jackets as set' forth in Stove! Patents Nos. 2,240,058 and 2,276,523, and the tubular knitted coverings therein disclosed are by reference made a part of the present disclosure so that it may be clearly indicated that thesaturant composition of the present invention may be applied to a variety of knitted jackets, including those formed from a plurality of spirally extending interconnected wales, the threads of said wales having interconnected loops.

.The present invention is directed to the solution of the problem presented by the use of knitted jackets, and particularly those of the character herein set forth, in the production of electrical conductors and similar articles. It has been ascertained that the exposure of the rubber covering to atmospheric influences on the bending, flexing and twisting of the conductor core in a completed electrical conductor can be prevented if the tubular knitted jacket is caused to adhere to the rubber and the threads of the knitted jacket are caused to adhere to each other since, when this condition is satisfied, on the electrical conducto and the core being flexed, twisted or bent, the protective knitted jacket does not permit the rubber insulating sheath to become exposed and therefore impairmentof the insulating properties of the rubber sheath and of the electric conductor is prevented.

It is desired to point out that with the introduction of the knitted tubular threaded jacket, the prior art procedure was followed; namely, the fibrous jacket was saturated with asphalt and finished with a finished coating of stearine Ditch. Thereafter, the stearine pitch coating was pro vided with a color coating, as for example, a cellulose base compound or an alcoholic soluble gum compound, as is well known in the art. When this procedure was followed, and an asphaltsaturating composition was used, it was discovered that the asphalt saturant did not cause the tubular knitted jacket to stick to the insulating sheath which it covered, and, further, that the asphalt did not possess sufllcient adhesive properties to cause the threads of the knitted jacket to stick one to the other when the so impregnated electrical core was bent, flexed and twisted.

After long experimentation, it was ascertained that the electrical conductor and its core' could be bent, flexed and twisted even when it carried the new knitted tubular protective jacket without exposing the underlying rubber sheath provided the tubular knitted jacket, and particularly that of the character herein disclosed, was treated with a saturating medium which would securely attach the loosely-held knitted tubular fabric to the underlying tubular sheath and which would also function to adhesively unite the threads of the tubular knitted jacket one to the other when thetsaturant solidified to an adhesive soft pliable s a e.

The knitted jacket, after being treated with the saturant of the present invention, then receives a finishing coat which maybe the prior art stearine pitch. Thereafter, the conductor is provided with a color coat.

Broadly stated, the saturating composition may be any material which is a liquid above 130 to 140 F., is capable of penetrating in and through the tubular knitted jacket, and on cooling assumes a soft pliable adhesive state, and bonds the tubular knitted jacket to the insulating sheath underlying it, and, further, bonds the threads of the knitted jacket one to the other, all in such a manner that when the conductor and its core is bent, flexed and/or twisted, the underlying insulating sheath will not be exposed to atmospheric influence. The saturating composition, when in a liquid or molten state, penetrates into the threads 0! the knitted tubular jacket and through the threads so that the jacket and individual portions thereof will be held over its entire under surface to the upper surface of the rubber insulating sheath, or the two will be held together by spots of adhesive in a, manner similar to the spot welding of one metal to another. When the saturant is cooled, it possesses, at room temperature, adhesive properties which tend to bind the tubular knitted jacket to the rubber insulating sheath, and tend to bind the threads of the jacket one to the other.

The saturant base of the saturant composition is applied to the tubular knitted jacket by immersing or passing the conductor core through abath of the saturant composition which is maintained in a thin fluid state. Naturally, the

temperature necessary to maintain the saturant in this condition will vary, but usually it varies between 260 to 350 F., but may be as low as 180 F. It is desirable to keep the impregnating temperature of 'the saturant composition as low as possible consistent with a liquid state because at elevated temperatures, the rubber insulatin sheath or other insulating medium may be slightly damaged. The saturating composition should be sufliciently liquid to penetrate the knitted jacket while having no deleterious effect on the insulating sheath, which is preferably rubber, but which, as pointed out, may be any other prior art material having insulating properties, and with the shortage of rubber, any of the equivalents of rubber may be used. The saturant composition cools from a temperature range of between 260 to 300 F. to a soft, pliable state characterized by the property, in its solid state, of causing the fibrous sheath to adhere to the rubber insulator and the various threads of the sheath to adhere one to the other.

The saturant composition may have as its saturant base a natural or synthetic gum or resin, acellulose ester or ether, chlorinated rubber, and the like, provided these materials have suflicient plasticity so that upon cooling from the temperature of application to normal room temperature or thereabcuts, the composition not only acts as an adhesive in the mannerset forth, but is also sufllclently soft and pliable to permit the elecknitted tubular jacket to separate from each other. If the saturant-base does not possess sumcient plasticity to function as specified, then there is added to the saturant composition a plasticlzer, which term as herein used includes the vegetable oils. The composite saturant composition will then possess the proper physical characterlstics which will enable it to set to a soft and pliable state.

It has been ascertained that particularly satisfactory results can be produced by using natural gums or natural or synthetic resins. Among the natural resins which may be used are rosin, .Pontianac, Manila gum, kauri, Congo, sandarac, shellac, dammar, ester gum, lime hardened rosin, and the like. Among the synthetic resins which may be used are the phenol aldehyde condensa= tion products, including phenol formaldehyde condensation products, furiural condensation resins, urea and thiourea aldehyde condensation products includingurea and thiourea formaldehyde'products, and alkyd resins including the glyptals. The alkyd resins constitute thecondensation product of a polyhydric alcohol and a poly basic acid. The g yptal resin is an example of an alkyd resin, said glyptal resin being a. condensation productof glycerol and phthalic anhvdrlde. Benzyl and styrene resins may be used, said resins being produced by polymerizing styrene or benzyl benzene. These resins, in many of their forms, are clear and colorless. Chlorinated rubber known under the trade name of Pliofihn, synthetic rubber compositions, and Paracoumarone-indene resins may also be used.

Acrolein and acrylic acid resins which are on the market under the trade name of Lucite-znay also be used. Few of the gums or esters form sufilciently plastic adhesives to be used without the addition of an agent acting as plasticizer and imparting to or augmenting the adhesive proper- Esomple 1 J her cent Ester 8 Soya bean ni 2.8

Emmple 2 Per cent Paracoumarone-indene resin- 86.3 Menhaden 11 16.? Example 3 Per cent Asphalt $1.2 Paracoumarone-indene resin 15A Cotton seed oil 23% Example 4 i Per cent Ethyl cellulose bl Soya bear oil as Eoompie 5 Per cent Lime. hardened rosin so Ethyl cellulose Castor oil 29 Example 6 Per cent Phenol formaldehyde resin l3 Linseed oil 25 Anti-oxidant 2 Example EPer cent Alkyd resin 37 Petroleum oil b Ester of phthallc acid i 4.

Example 8 Per cent Manila gum d7 Tricresyl phosphate 23 Example 9 Per cent Shellac 5:3 Urea formaldehyde resin 31 Dibutyl phthalate l5 ties of the saturant. For example, it has been i found that while'ester gum may be used as a base of the saturating compound, it is highly desirable to add thereto a material which will increase the adhesive properties thereof and plasticize it. Such a material, is the mineral, vegetable, or animal oil. Among the oils which may be combined with the ester gum or similar base are petroleum derivatives including lubricating oil, parafiln, vegetable oil such as castor oil, linseed oil, soya bean oil, corn oil, China-wood oil, oiticica oil, cocoanut oil, rapeseed oil, and the like. Fish oil is a representative of a suitable animal oil. The plasticizing and adhesive increasing agent may also be organic compounds, as, for example, esters of phosphoric acid or esters of phthalic acid. The chlorinated polynuclear aromatic hydrocarbons also function well in the above capacity.

asonear From the standpoint of expense, ester is the most desirable saturant base to use and in order to plasticize the'gum, it is desirable that there be present in the satu'rant composition a suitable plasticizer. The vegetable oils, and particularly soya bean oil, have given very satisfactory results. The ester gum may be produced by melting ordinary resin in a kettle with the required amount of glycerine. The molten ester gum may be allowed to cool, or, if desired, the saturant composition may be produced by adding to the molten ester gum a plasticizing constituent which also preferably imparts to the saturant composition adhesive properties. The acid number of the ester gum used in carrying out the present invention is not critical; it may be low or high, but the physical hardness or brittleness i of the ester gum determines the kind and amount g It is quite desirable that the saturant compo- The following are examples of suitable saturant compositions:

The saturant may solidify to a sticky of plasticizer which may be instead of using ester gum, rosin itself, or lime hardened rosin may be used. While the plasticizing-constituent of the saturant composition is preferably a non-drying or semi-drying oil so that the composite saturant composition will not lose its salt pliable adhesive condition after being applied to the knitted jacket, a drying, oil may be used, as for example, linseed oil or China-wow 011 provided an anti-oxidant is present in the saturant composition to substantially prevent or inhibit oxidaticnoi the r 1. oil. It is desirable used. In some cases,

The ethyl cellulose ether is used because this derivative is easily and readily available and, further, it forms a tougher and harder film than any of the other cellulose ethers. It has a very low burning rate and is free from discoloration from sunlight. The ethyl ether set forth in Example 4 may be replaced in whole or in part by any one or a mixture of thermoplastic cellulose ethers having the properties above set forth. These cellulose ethers include propyl cellulose, butyl cellulose, benzol cellulose, ethyl benzol cellulose, ethyl propyl cellulose, methy butyl cellulose, and the like. The term thermoplastic cellulose ether" is intended to designate those cellulose ethers which at room temperature and slightly above are solid and which melt tb a liquid at elevated temperatures. The saturant composition may contain a gum or resin in conjunction with a cellulose ether of the kind above referred to, and especially ethyl cellulose. As indicated in Example 5, the saturant base contains a predominating quantity of a resin; namely, a

lime hardened rosin, and a relatively small proportion of a cellulose ether. However, it is not intended to limit the invention to a saturant base in which the resin predominates over the cellulose ether. The reverse may be true, and the cellulose ether predominate over the resin. Where necessary, the plasticizer may be present in the saturant composition in an amount varying between 2% to about 50% based on the weight of the composite saturant composition. The plasticizers are present in the respective examples in the following amounts: Example 1, 23%; Example 2, 17%; Example 3, 23%; Example 4, 46%; Example 5, 29%; Example 6, 25%; Example 7, 13%; Example 8, 13%; and Example 9, 15%.

The saturant base as shown in Example 9 may consist of a natural resin illustrated by shellac and a synthetic resin illustrated by a urea formaldehyde resin. Obviously, for the shellac, other natural resins may be substituted, and other synthetic resins may be substituted for the urea formaldehyde resin.

Referring to Example 7, it is to be noted that the saturant base comprises an alkyd resin, the term alkyd designating a well known type of resin. It is within the province of the present invention to mix the alkyd resin with a cellulose ether of the type herein described, the latter being present in a predominating proportion or the alkyd resin being present in a predominating proportion and the cellulose ether present in a minor proportion.

Th examples given are merely illustrative of saturant compositions which may :be used to carry out the invention. Having once pointed out the problem to be solved and its solution, those skilled in the art will be able to formulate equivalent saturant compositions for filling the basic requirements herein set forth.

The proportions set forth in the above ex amples are by way of illustration and not by way of limitation. The various ingredients may be varied considerably and still come within the spirit of the present invention. The physical characteristics of the saturant; namely, its ductility, its tensile strength, its adhesiveness, its ability to penetrate into and through the knitted fabric Jacket, its capacity to retain these characteristics for a considerable period oftime, its thermal nature including its liquidity at above 130 F. and its ability to be maintained in a solid state at temperatures below 130 F., are the factors which determine the usefulness of the saturant base in carrying out the present invention, and therefore any combination of materials which possesses the properties herein set forth including gums, resins and cellulose ethers with or without a plasticizer such as oil or those of the character set forth in the examples, may be satisfactorily used.

The stearin pitch which may be used as the finishing coat to be applied over the knitted jacket which has been saturated with the above disclosed saturant composition, typifies the residue which remains in the retorts from which it is distilled by vacuum distillation, such free fatty acids as stearic, palmitic, oleic, myristic, and the like, such as may be obtained from oleo stearine, lard, oil, cotton seed, soya bean oil, corn oil, and the like, after said materials have been hydrolyzed for the recovery of their glycerol content. This residual pitch is a solid, jet black in color, containing free carbon in suspension,

- and is a highly polymerized condensed residue of a rubbery-like nature, which becomes tacky and flows at slightly elevated temperatures.

of course. such a material may be mixed with asphalt or wax, or with both or these ingredients may be copper, or aluminum, or any other electrical conductive wire, any equivalents of the rubber may be used provided the equivalent material has comparable insulating properties. Naturally, the synthetic vulcanizable rubbers may be used, as, for example, that derived from butadiene, isoprene, dimethyl butadiene, or other homologs or analogs of butadiene.

It is desired to point out that any suitable color coating composition may .be applied over the finishing coat. Examples of satisfactory color coating compositions are as follows:

, Table 3 s Per cent Metallic red oxideu 21.5 Filmscrap or cellulose nitrate 8.? Shellac 1.2- Acetone 61.08 Methyl alcohol 1.4;,1 Beta nap .16

Table 4 Per cent American whi in 9.65 Ashestine 5.60 Red iron oxide La 15.30 Filmscrap 7.15 Alkvd res 3.28 Aluminum stearate 9.87 Beta naphi-hnl @995 Hydrogenated petroleum iraction 7.95

Acetone 50.19?

Table 5 Per cent Titanium di 871i Ferric oxide yellow 1.88 Lea-d chr 7. 08 Red iron oxide" 1.25,

ll ilmscrap 5716 Alkyd resin 3.98 'lvialeic .ahhydride resin 2.475 Blown castor oil 1.88

Methyl acetate 33.49 Methyl alcohol 5.91 Beta n h hn 0.005

While the stearine pitch coating may be used as the finishing coat, the tubular knitted jacket carrying the saturant herein disclosed may be flexed and/or twisted, said basic material having r a primary covering therefor and a knitted jacket of any shape covering said primary covering, said jacket being formed of interconnected wales, the successive threads of said wales having interconnected loops. The knitted jacket may be impreg-= nated with the soft pliable adhesive saturant composition herein set forth to adhesively unite the knitted jacket to the primary covering and to also adhesively unite the threads of the jacket together so that upon bending and/or flexing and/or twisting of the base material, the primary covering,

irrespective of whether or not it has insulating properties, is not exposed to deteriorating atmospheric influence.

Having thus described the invention, what is claimed as new and desired to be secured by Let ters Patent is: v

1'. The method of manufacturing an electrical conductor having a conductor wire, an insulating jacket thereon, and therecver a tubular knitted protective jacket comprising heating a saturant to substantially remove therefrom all volatile matter, impregnating said knitted jacket with said saturant and adhesively uniting the knitted jacket to the insulating jacket while adhesively uniting the threads oi the lmitted jacket together While the invention is of particular.

accuser 7 so that upon subjecting the so-treated conductor to substantial stresses the insulating jacket is not exposed to deteriorating atmospheric conditions. 2. The method of manufacturing an electrical conductor having a conductor wire, an insulating jacket thereon, and thereover a tubular knitted protective jacket comprising heating a plastic resin saturant to substantially remove therefrom all volatile matter, impregnating said knitted jacket with said saturant and adhesively uniting the knitted jacket to the insulating jacket while adheslvely uniting the threads of the hiitted jacket together so that upon subjecting the sotreated conductor to substantial stresses the in sulating jacket is not exposed to deteriorating atmospheric conditions.

3. The method of manufacturing an electrical.

conductor having a conductor wire, an insulating jacket thereon, and thereover a tubular mitted protective jacket comprising heating a saturant to substantially remove therefrom all volatile com= ponents, maintaining the so-treated saturant at a temperaturevarying between 180 F. to 350 lid, impregnating said knitted jacket with said heated saturant free or volatile components and adhe= sively uniting the knitted jacket to the insulating jacket while adhesively uniting the threads of theknitted jacket together so that upon subjecting the so-treated conductor .to substantial stresses the insulating jacket is not exposed to deteriorating atmospheric conditions.

i. The method or manufacturing an electrical conductor having a conductor wire, an insulating jacket thereon, and thereover a tubular knitted protective acket comprising heating a plastic resin saturant to substantially remove therefrom all volatile components, maintaining the sotreated saturant at a temperature varying between 180 F. to 350 ii, impregnating said knitted jacket with said plastic resin saturant free of volatile components and adhesiveiy unit= ing the knitted jacket to-the insulating jacket while adhesively uniting the threads of the knitted jacket together so that upon subjecting I hesively uniting the threads of the-knitted jacket together so that upon subjecting the so-treated conductor to substantial stresses the insulating jacket is not exposed to deteriorating atmospheric conditions.

6. The method of manufacturing an electrical conductor having a conductor wire, an insulating jacket thereon, and thereover a tubular knitted protective jacket comprising treating said knitted jacket with a saturant containing a resin and a thermoplastic cellulose ether compatible with said resin, said saturant being sufiioiently liquid to penetrate the knitted jacket while exerting little deleterious efiect on the insulating jacket thereunder and adhesively uniting the knitted jacket to the insulating jacket while adhesively uniting the threads of the hitted jacket together so that upon subjecting the so-treated conductor to stresses the insulating jacket is not exposed to deteriorating atmospheric conditions, and applying a flame-proofing coating to the so-treated knitted jacket.

7. The method of conductor having a. conducting core, comprising applying directly to saidcore a vulcanized rubber insulating jacket and applying directly over said insulating Jacket a single relatively loose knitted tubular jacket only, impregnating-said knitted jacket with a hot non-vulcanizable liquid adhesive maintained at a temperature varyingbemanufacturing an electrical tween 180 and 350' F. and which "a by cooling only to a soft pliable solid' adhesive state and in its set state has sumcient adhesiveness to adhesively unite the threads of the knitted jacket together and hold the knitted'jacket in adhesive contact with the insulating Jacket to prevent the latter from being exposed to deteriorating atmospheric influences upon bending flexing and twisting of the conductor, and directly cooling the so-

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