US 2022827 A
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Description (OCR text may contain errors)
Dec. 3, 1935. s. RUBEN 2,022,827
INSULATED WIRE Filed Sept. 29, 1932 fwprey/zvf/eswow m INVENTOR.
. 1932; I described an insulating compound for electrical conductors, comprising a iinely divided [Patented Dec. 3, 1935 UNITED STATES PATENT OFFICE 'lNsULA'rED WmE Samuel Ruben, New Rochelle, N. Y., assigner to Vega Manufacturing Corporation, Wilmington, Del., a corporation of Delaware Application September 29, 1932, Serial No. 635,304
, .pregnated'textile covered metallic body in which l textile covered wire.
Further objects will be apparent from the disclosure.
In the accompanying drawing Fig. 1 is a view partly in section, of an impregnated fabric covered Wire;
Figs. 2 and 3 are similar views of a modification of the invention;
Fig. 4 shows an impregnated cellulose fabric; and
Fig. 5 illustrates an impregnated heat fabric..
. In my issued Patents #1,896,041, #1,896,042, and #1,896,043 and co-pending applications, Serial No. 580,531 of 12th December, 1931; 619,019 of 9th July, 1932 and 631,654 of 3rd September,
inorganic refractory material, such as an oxide and a Water-insoluble resinous binder, such as an oleoresinous varnish. Where high heat resistance was a factor, the compound contained an inorganic binder, such as boric acid or other boron compounds, eiective at elevated temperatures.
I have found that if a textile covered Wire, such as the conventional silk or cotton covered magnet Wire, is impregnated with a compound such as described, that the heat resistance, dielectric strength and life of the insulation are greatly increased. This is due in a great measure to the to the fact that the finely divided inorganic materials filter through the textile winding to the wire and also into the textile itself. When an inorganic binder, such as a berate is present, the heat and llame resistance is very high.
If the textile covered wire has iirst vhad an initial coat of the refractory oxide-resinous binder insulation over. which the textile has been Wound, the refractory ability of the insulation is still further increased by impregnation.
If the textile covered Wire has rst had an initial coat of conventional varnish enamel or rubber over which the textile has been wound, the refractory ability of the insulation is much increased.
The fabric textile to be impregnated may be in Asheet or tape form and unattached to metal at the time of impregnation y I may select as a suitable impregnating compound, one of the insulating compounds mentioned in the copending applications referred to, 10 which include as resinous or water-insoluble organic binding materials, spirit varnishes of the shellac type, oleoresinous varnishes, phenol varnishes, rubber varnishes, oil-rubber varnishes or alkyd resin lacquers, to any one or more of which is added the finely divided insulating compound which may consist of one or more of the oxidesof such elements, as iron, chromium, titanium, beryllium, magnesium, aluminum, silicon, tantalum, vanadium, manganese, cobalt, nickel, copper, zinc, molybdenum, tungsten, lead, thorium, zirconium. Where the borates, silicates, hydroxides or hydrates of these elements form insulating compounds, these may be used. Mixtures containing more than one compound, for example beryl, chromite, rutile or mica, may also be used in combination or otherwise.
Finely divided aluminum may in some cases be substituted for one of the refractory materials, as aluminum in a finely divided state is not conductive, probably due to the thin film of oxide which seems to naturally form upon its surface. If desirable, the thickness of this insulating lm can be materially increased by chemical treatment, as for instance, by immersion in nitric acid.
In a number of cases it will be found desirable to add to the mixture of refractory material and organic binder, an inorganic binding and reacting agent. AThe cho-ice of this material is governed to some degree by the temperature which the insulating compound will be called upon to withstand, one of the objects in using a compond of this nature being to provide a. binding action after the organic materials have lost their ability to hold the refractory material in place. Another reason is that these compounds usually increase heat and iire resistance of the organic materials with which they are mixed or come in contact with or impregnate and tend to preserve them from deterioration. It is Well known that organic insulations definitely deteriorate with age and in time become conductive, due to carbonization. This eiect is rapidly accelerated by heat, such as would be inherent in motors, etc. (see be used. Theseinorganic binders may be added separately or in the form of a compound or. mixture with any of the other components and should bev ground to the same fine dimension. 1 Preferably, they should have a melting or flowing point lower than the carbonizatlon temperature of the organic materials used.
The following illustrates4 typical mixtures: rst, as to the organic binding material; (1) 100 grams flake shellac and 100 grams of Venice turpentine dissolved in 400 cc. alcohol; (2) oleoresinous varnish consisting of ester and kauri gums,
China wood and linseed oil, turpentine andmineral thinner in proper proportions, heated to about 500 F.; (3) a phenol resinous varnish made up with proportions of #2 above and a compound consisting of China wood oil, fish oil and phenol formaldehyde resin heated together to about 450 F. thinned out with toluol or xylol; (4) an oilr'ubber varnish consisting of varying amounts of rubber, such 'as from 25% to 50% rubber dissolved in an oil resinous compound. Various other types of varnish and lacquers are described in my copending applications, for instance,'gly
cerol-phathalate resin varnish, etc.
To 400 cc. of a properly thinned out compound, such as one of the types described, I add 200 grams of one of the finely divided inorganic insulating materials hereinbefore mentioned and :grind these together until the solid matter has beenreduced to a very fine dimension.. If it is desired to add an inorganic binder, flame or heat resistant compound such as boric acid, this is preferably put in and ground with the mixture.
It may be added in'amounts from 2% of the n amount of the insulating material up to 75%.
'I'he amount of insulating material, such as the oxide, may be determined by its specic gravity, bulking and wetting qualities and by the degree of refractoriness desired. For instance-if nely divided aluminum were used, only a small proportionate Weight comparedwith heavy oxide would be necessary.
The size of the solid inorganic materials should be not greater than will allow them to pass through a 200 mesh screen and much better results are obtained if they are small enough to pass through a 300, 350 or 400 mesh screen.
It will be recognized, of course, that the figuresv given and the composition of the insulating compound may be varied within wide limits according to the use to which the compound is to be put and the amountv of heat to be encountered.
That is to say, in the formula given above, twice 4the amount of oxide may be used or only 115 as much and the boric acid might be 2%l of the amount of oxide or 100%. The organic binder or carrier should'be of proper consistency in relation to the specific gravity of the solid materials used so that these materials do not deposit too rapidly. A typical coating mixture might comprise 400 cc. of a compound consisting of one part of rubber dissolved in three Darts of an oil-resinous compound, 200 grams finely divided iron oxide and 25 grams of boric acid, ground together. Such a mixture would also be suitable as an impregnating compound.
Afterv the wire hasbeen coated the textile 5 winding such as cotton` or silk is wound on by machine in a manner well known in the art. For someapplications the textile may be wound directly on the bare wire without surface insulation. Also other cellulosic materials, such as 10 paper or certain forms of regenerated sheetcellulose, may be used. t
In impregnating an insulated wire for instance, of the textile covered type'above referred to, it is desirable to use a continuous process. 15 'Ihe wire is passed through cups or baths containing the impregnating compound and is then dried vand preferably heated in ovenslocated between the cups. The amount of heat applied should be such as will not seriously injure the 20 textile covering. I n this connection, the use of a heat or iire resistant material such as boric acid in the impregnating compound is highly useful. After the wire is impregnated and dried, 5
it may be rolled up into spools. 2
If sheet or tape fabric material is to be impregnated, this may be passed through the impregnating compound, either lcontinuously or otherwise as may be found best and then dried and/or baked. 30
Drying and baking schedules are determined in a large degree by the amount of and quality of the solvents used with the organic binder and by the nature of the binder base. For instance, a shellac-alcohol mixture will give a rapid drying 35 while an oil-resinous naptha thinner type varnish will dry much slower.
For some applications, it is desirable -to incorporate the impregnating material as an initial component of the fabric or sheet material, for ln- 4p stance, in the production of sheetlaminating material for insulation to replace sh paper, etc. This may be accomplished by taking brous material such as asbestos or cotton or silk, and mixing it with one of the types of impregnatingy compounds described; preferably of the oilrubber oxide type and then rolling into sheets which 'can be dried and baked. A highly useful and relatively thin sheet material composed of low priced asbestos bres, -a 50/50 oil-rubber 50 compound and preferably containing a small amount of a boron compound, such as boric acid, can be obtained.
In order to -illustrate the invention, reference is made to the accompanying drawing. A
In Fig. 1, the wire (I) has a cotton winding (2) and the wound wire has been impregnated with compound (3)' consisting of a resinous binder, a finely divided oxide and an inorganic binder serving as a heat and fire resistant material.
In Fig. 2, the wire (I) has an insulating coating (d) of the enamel or oxide-resin or rubber voe over which is cottonwinding (5)`and Vthe wire as such has been impregnated with compound (3), similar to compound (3) of Fig. l.
In Fig. 3, is shown a piece of thread (1) impregnated with impregnating compound (3), similar to compound (3) of Fig. 1. It will be observed that the impregnating material not only covers the whole thread but has filtered through to compound (3) of Fig. 1. 75
The fabric (l shown in Fig. 3, might also consist in whole or in part of non-cellulosic materials such as asbestos.
In Fig. 5, is shown a sheet lamination (il) consisting of a mixture (i3) of asbestos bre,
an oil-rubber compound and boric acid.
1. A wire having a surface insulation comprising a mixture of finely divided oxide, a resinous binder and a boron compound, and having a textile winding over said insulation, said textile being impregnated with a mixture of finely divided oxide, a resinous binder and a boron compound.
2. A Wire having a surface insulation comprising a mixture of finely divided oxide, a resinous binder and a boron compound, and having a textile winding over said insulation, said textile being impregnated with amixture of nely divided oxide, a resinous binder and a boron compound.
3. A wire having a surface insulation comprising a mixture of nely divided oxide, a resinous binder and a heat resistant inorganic binder, and having a textile winding over said insulation,
said textile being impregnated with a mixture of ilnely divided chromium oxide, a resinous binder and a boron compound.
` 4. A wire having a surface insulation comprising a mixture of iinely divided chromium oxide, 5 a resinous binder and a boron compound, and having a textile winding over said insulation, said textile being impregnated with a mixture of finely divided chromium oxide, a resinous binder and a boron compound.
5. A wire having a surface insulation comprising a mixture of 200 grams finely divided chromium oxide, 25 grams of boric acid and 400 cc. of a compound consisting of one part of rubber dissolved in three parts of an oil resinous binder, a textile fabric winding over said insulation, and an impregnant of nely divided oxide, a resinous binder and a boron compound within said fabric.
6. A wire having a surface insulation comprising a mixture of finely divided oxide, a resinous binder and a heat resistant organic binder, a textile fabric over said insulation, and an impregnant identical in composition to that of the insulation, in said fabric.
Patent No. December 3, 1935.
eersreeiyixm es follower Page 5, "egamien read inergamie;
read with 'bh' Correction therein ef' me Cese "met erre? @fonemi-41:5 in the Specification Office.
Signed. A. D 1957.
Henry Van Aredele (Seal) Acting Commiseoner o1" Patents.
Patent No. 2, 22,827- December 3, 1935.
SAM EL RUBEN r, :is errer appenrs in une printed speeif'iction 0f the above n1. u .nis :requiring caorrection es follows: Page C5, eeeond column, line @Laim 6, for the werd. "Organice" read inorganic; and the Seid 'rt should with this correction therein that 'the may 'to 'the record. 0f t'ne Cese in the Paterna Office.
Signed ernia .Sealed 23.1%. of September, A. Do 1957.
Henry Van Arsdale (Seal) Acting Commissioner of Patents.