US1312093A - Iobo h - Google Patents

Description

*UNITED STATES PATENT onnrcn TJEU H.,BA .EKEI|AND, 0F YONKERS, NEW YORK, ASSIGNOR TO GENERAI BAKELITE COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

"rnnn'rmu rune-01L AND conrmc on. mrnn'anarme owners THEREWITIL lfilfifi t No Drawing. I

To all whom it may concern:

' Be it known that l, LEO H. BArmnnANo, a citizen of the United States, residing at Yonkers, in the county of Westchesterand State of New York, have invented certain new and useful Improvements in Treating Tung ".0l1 and Coating or llmpregnating ()bjects Therewith, of which the following is a specification.

llt is known thatso-called tung oil or Chinese Wood oil polymeriz'es or solidifies under the continued action of sufficiently high temperatures. Thus, ordinary tung. oil Wlll elatinize and solidify in time at about 232 b. This solidification is independent of any process of oxidation due to j atmospheric oxygen, and is therefore quite distinct from the hardening process induced in linseed oil, or in other so-called"drying oils, in which the solidification is due.to oxidation Solidified tung oil is an excellent electrical insulator, and has furthermore the advantage that it does not melt when subjected to higher temperatures. In this respect it is qulte different from the resinous substances which have been used heretofore in the electrical art for impregnating coils' of this material for impregnation difiicult hill or impracticable, for the reason that at the high temperatures at which solidification occurs rapidl organic materials and certain other substances are liable to damage or destruction through the action of the heat. This applies to such materials as contain fabric or fiber,- paper, soft solder, enamel, etc., which are commonly used in the construction of electricaldevices. Furthermore, the application of these high temperatures is by no means easy, involving many technical difficulties and .com lications. It has been asserted that the lntroduction of certain substances, for example metallic salts, reduces the temperature at which solidification occurs; but the introduction of such substances constitutes an element of danger for electrical purposes, particularly where very high voltages are to be used.

' The present invention comprises a' process Specification of Letters Patent.

I Application filed January 16, 1917. Serial No. 142,693:

whereby'the gelatinization or solidification of the tungoil may be carried out ata relatively low temperature, and may be accomplished with easily available means, for eitample steam and ordinary apparatus heated by steam. ll base my process on the fact that tung oil, by a preliminary heating at relatively high temperatures followed by coolmg, acqulres the property of gelatmizing rapidly at temperatures materially below those of the initial heating. 'Tung oil which has been subjected to such preliminary treatment can, it is found, be stored and kept in stock for long eriods, not only at ordinary temperatures, ut at temperatures'as high as 80 or even 100 C. lln certain instances the treated oil has been kept for more than a month at 100 C. without gelatinizingg and at 75 to 80 C. it appears to keep indefinitely, except for some oxidation from the surface downward when exposed to the air. The above facts are of great technical importance when it is taken into considera tion that in the impregnation of coils and other electrical devices the operation is customarily carried out in large tanks heated by steam jackets, the conditions being such as to render it impractical frequently or rapidly to cool the contents, which are accordingly kept warm for long periods.

The invention comprises also the modified oil capable of solidification at a rela? tively low temperature, and the process involvlng the coating-or impregnation of objects with such modified oil.

l[ have found it essential for practical urposes that the treatment of the oil eading to its gelatinization or solidification should be carried out in two distinct stages. The first stage is carried out at relatively high temperatures while avoiding solidification. For this purpose the oil is preferably quickly heated to 205 to 210 6., and is held approximatel at this temperature for some two and onealf hours, with sufficient stirring to prevent it from burning on the bottom of the pot. After sufficient treatment, a

sample of the oil when cooled. should have about the consistence of ordinary molasses: A small scale test will indicate when this point is reached. As soon as the desired condition is attained the oil is quickly cooled;

. thinner.

by any appropriate means, and may be at once stored for further use. now be found to undergo gelatinization readily at temperatures approximatmg 150 to 160 C. in eight or nine hours, while as stated above, it may be kept at temperatures as high as 80 or even 100 C. for several weeks without material change. I However, in order to avoid alteration by oxidation from the surface, it is desirable to store the oil in tanks free from oxygen or containing" an inert gas, as for instance flue gas, illuminating gas, carbon dioxid, nitrogen or hydrocarbons, thereby avoidin the formation by oxidation of a surface s in upon the liquid.-

The thickened tung oil, prepared as indicated above, can be used to excellent advantage for impregnating or coating paper, fabrics, wood or the like. For such purposes the ordinary methods of impregnation and coating are readily available. Usually there is no necessity for the addition of thinners or reducers, although it is'obvious that oils, resins or the like, may be added if desired. In certain cases the addition of a lighter or more mobile tung oil is beneficial as a This prepared tung oil is also advantageously used in con unction with suitable fillers or other substances for the preparation of molding mixtures.

Electric coils or similar devices impregnated with tung oil, which is afterward gelatinized or polymerized, present the disadvantage that they do not sufiiciently resisted the action of transformer oils and other liquids used in transformers, such liquids exerting a solvent or swelling action on the polymerized tung oil. In order to avoid this such devices may be incased in suitable envelops which will prevent access of the liquid to the gelatinized tung oil. Any suitable material which is not ma terially affected by the transformer oil or similar liquids, and which does not liquefy too readily under an increase of temperature, can be used to advantage for this purpose. For example, transformer coils impregnated with polymerized tung oil, may be coated with a protective layer of a material consisting of or containing the known infusible and insoluble phenohc condensation products; or the condensation product or other protective material, instead of being applied directly,may be embodied in or associated with a protectivelayer of fabric; or it may be used in conjunction with other suitable materials, as for example inert fillers or finely divided. substances.

While I have specified in the foregoing description certain definite temperatures and times of treatment as constituting the 'most advantageous operating conditions known to me, it is to be understood that the invention The oil will ried out at temperatures somewhat lower.

than those specified as most desirable, sufficient time beinggiven for attaining the results desired in the respective cases. Caution should be used however in employing during the preliminary treatment, temperatures much above 210 C., as there is danger that the reaction may pass beyond control.

In order to utilize my invention for the manufacture of molded articles such as molded insulators and the like, suitable molding mixtures are prepared by intimatel mixing the prepared or preliminarily heated oil with sultable fillers or finely-divided solid materials. Or if desired the filler may be added directly to the raw oil and the mixture subjected to the preliminary heat treatment as described above; but in general it is much simpler first to prepare the oil and then to incorporate the filler. The proportion of filler to oil ma vary through a rather wide range, accor ing to the character of the filler and the purpose in view. In general, a mixture containing in the neighborhood o f.70 parts of filler by weight to 30 parts of oil will be found suitable, although 80 parts of filler to 20 of oil may afford acceptable molding mixtures for certain purposes.

Such molding mixtures can be pressed in molds or in any suitable devices according to the well known methods. A simple method is to shape the cold or warm molding mixture by application of sufiicient pressure in the mold, and then to subject the molded article to a further hardening process in an oven or by equivalent means at a temperature of about 170180 C. At this temperature, 20 to 24 hours will sufiice to produce the maximum hardness of which the mixture is capable. stood that either higher or lower temperatures may be used, but I have found that at the temperature indicated the molded articles show less tendency to distortion and the process may be comp eted within a reasonable time in a baking oven.

Among the suitable fillers clay, silex, asbestos, and wood fiber may be mentioned as typical of many others, such ,fillers being used either alone or in admixture with each other, or in conjunction with pigments or dyes. For some purposes the addition of It will be under ieiaoaa asphaltum or asphaltum compounds, including the so-called bituminite, maybe of advantage. An illustrative molding mixture may contain The ingredients are mixed as intimately as possible, and the molding and subsequent baking are performed as described above. 7

lln order to improve the surface of the molded articles, they may be coated with a suitable external protective layer, for example a coating of asphaltum, or better, a protective enamel of a phenolic condensation product, preferably of the infusi'ble type, this enamelbeing converted into its infusible and insoluble state by application of heat, or of heat and pressure, in accordance with the methods now well understood in the art.

The method of molding herein described, and the molded product, are claimed in my divisional application Serial No. 211,639, filed Jan. 12, 1918.

I claim 1. As a new article of manufacture, modified tung oil, practically stable at temperatures up to 80l00 (1., but solidifyin r at temperatures substantially below 200 2. As a new article of manufacture, modified tung oil, practically stable at temperatures up to 80100 0., but solidifying without substantial evaporation at temperatures substantially below 200 C.

3. As a new article of manufacture, modified tung oil, practically stable at temperatures up to 80-100 (l, but solidifying at a'loout 150-160 C.

temperature while avoiding solidi cation thereof, and thereafter solidifying the oil by application of heat at a temperature below that of the initial heating.

6. A method of treating tung oil, consisting in heating the oil to a temperture of approximately 200 C. while avoiding solidification thereof, and thereafter solidifying the oil at a temperature approximating USO-160 C.

7. A method of treating tung oil and impregnatingor coating objects therewith, consisting in heating the oil to a relatively high temperature while avoiding solidification thereof, and thereafter solidifying the oil by application of heat in presence of the object to be coated or impregnated, at a temperature below that of the initial heating.

8. A method of treating tung oil and impregnating or coating objects therewith, consisting in heating the oil to a temperature of approximately 200 C. while avoid ing solidification thereof, and thereafter solidifying the oil by application of heat in presence of the object to be coated or impregnated, at a materially lower temperature.

9. A method of treating tung oil and impregnating or coating objects therewith, consisting in heating the oil to a tempera ture of approximately 200 C. while avoiding solidification thereof, and thereafter solidifying the oil in presence of the object to be coated or impregnated, at approximately 150-160 C.

10. An article coated or impregnated with solidified tung oil, and provided with an external coating resistant to transformer oil and ordinary solvents.

11. An article coated or impregnated with solidified tung oil, and provided with an external coating of an infusible and insoluble phenolic condensation product.

In testimony whereof I aflix my signature in presence of two witnesses.

. LEO H. BAEKELAN D.

'Witnesses:

ALBERT lDUBIEL, Manna EVANS,