US1372114A - Molded article and method of making same - Google Patents

Description

, UNITED STATES PATENT OFFICE.

.LEO H. BAEKELAND, OF YONKERS, NEW YORK, ASSIGNOR TO GENERAL BAKELIETE COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

MOLDED anrrcnnan'n mn'rnon or Maxine samn Specification of Letters Patent.

Patented Mar. 22, 1921.

No Drawing. Original application filed January 16, 1917, Serial No. 142,693, now Patent No. 1,312,093, dated August 5, 1919. Divided and this application filed January 12, 1918. Serial No. 211,639.

To all whom it may concern Be it known that I, LEO H. BAEKELAND, a citizen of the United States, residing at Yonkers-in the county of Westchester and State of New York, have invented certain new and useful Improvements in Molded Articles and Methods of Making Same, of

which the following isa specification.

It is known that so-called tung oil or Chinese wood oil polymerizes or solidifies under the continued action of sufficiently high temperatures. Thus, ordinary tung 011 higher temperatures, In this respect it 15 I quite different'from the resinous substances which have been used heretofore in the electrical art for impregnating coils and like elements. However, the fact that the polymerization takes place at such relatively high temperatures renders the use of this materialfor impregnation difficult or impracticable,

for the reason that at thehigh temperatures at which solidification occurs rapidly, organic materials and certain other substances are liable to damage or destruction through the action of theheat. This applies to such materials as contain fabric or fiber, paper,

, soft solder, enamel, etc., which are commonly used in the construction of electrlcal devices.

, many technical difficulties an tions. duction of certain substances, for example Furthermore, the application of thesehigh temperatures is by no means eas involving com lica- It hasbeen asserted that the intrometallic salts, reduces the temperature at which solidification occurs; but the intro- ,duction of such substances constitutes an element of danger for electrical purposes, particularly where very high voltages are to, be used.

, In the practice of the present invention, the gelatinization or solld-ification of the tung oil is carried out .at a 'relatlvel low temperature, and may be accomplishe iwith by any ap easily available means, for example steam and ordmary apparatus heated by steam. I base my process on the fact that tung oil, by a prellm nary heating at relatively high temperatures followed by coolin acquires the property of gelatinizing rapidly at temperatures materially below those of the ,in-

itial heating. Tung oil which has been subjected to such preliminary treatment can, it is found, be stored and ke t in stock for long periods, not only at or inary temperatures, but at temperatures as high as 80 or even 100 C. In certain instances the treated 011 has been kept for more than a month at 100 C. without gelatinizing; and at to C. it appears to keep indefinitely, except for some oxidation from the surface downward when exposed to the air. The

above facts are of at technical importance when it 1s taken into consideration 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.

I have found it essential for practical purposes that the treatment of the oil leading to its gelatinization or solidification should be carried out in two distinct stages. The

first stage is carried out at relatively high temperatureswhile avoiding solidi cation and reserving a fluid consistence of the oil. or this purpose the oil is preferably quickly heated to 205 to 210 Q,- and is held approximatel at this temperature for some two and onealf hours, with suflicient stirring to revent it from burning on the bottom of t e pot. After sufiicient 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 ropr-iate means, and may be at once store for further use. The oil will now be found to undergo gelatinization readily at temperatures approximating 150 to 160 C. in eight or nine hours, while as 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, illumivantage 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 nonecessity for the a( dition 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 thinner.

This prepared tung oil is also advantageously used in c0njuncti0n with suitable fillers or other substances for the preparations 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 sufficiently resist 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 materially 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 phenolic condensation products; or the condensation product or other protective material, instead of being applied directly. may be embodied in or associated with a protective layer 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 is not restricted to such specific temperatures or times of treatment, or to the other details of manipulation above described, inasmuch as time and temperature are in this case to some extent correlated factors. in the sense that either may be varied within reasonable limits with appropriate variationof the other. Thus, somewhat higher temperatures may be used pr0- vided the time of treatment is appropriately shortened; and similarly, the preliminary treatment as well as the final solidification of the oil may be carried out at temperatures somewhat lower than those specified as most desirable, sufiicient time being given for attaining the results desired in the respective cases. Caution should be used however in employing during the preliminary treatment, temperatures much above 210 (1., 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 intimately mixing the prepared or preliminarily heated-oil with suitable 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 may vary through a rather wide range, according .to the character of the filler and the purpose in view. In general, a mixture containing in the neighborhood of parts of filler by weight to 30 parts of oil will be found suitable, although 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 l70180 C. At this temperature, 20 to 24 hours will suffice to produce the maximum hardness of which -the mixture is capable. It will be understood 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 completed within a reasonable time in a bakin 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 asphaltum or asphaltum compounds, including the so-called bituminite, may be of advantage. An illustrative molding mixture may contain 75 parts by weight of prepared tung oil.

100 parts silex.

100 parts short asbestos fiber.

100 parts wood flour.

' treatment whereby solidification of the oil as possible, and the molding and subsequent baking are performed as described above.

In orderto improve the surface of the molded articles, they may be coated with a suitable external rotective layer, for example a coating o asphaltum, or better, .a protective enamel of a phenolic condensation product, preferably of the infusible type, this enamel being converted into. its infusible'and insoluble state by application of heat, or of heat and pressure, 1n accordance with the methods now well understood in the art.

This application is a division of my coending application Serial No. 142,693, filed anuary 16, 1917, now Patent #1,312',093-

Aug. 5, 1919.

I claim I 1. A method of making molded articles,

comprising subjecting tung oil to a heat-' treatment whereby solidification of. the oil is avoided but it acquires the property of solidifying by prolonged heating at a lower temperature; molding a mixture comprisin the treated oil compounded witligigfsuitable filling material; and bakin ar-lticle to efiect solidification o the-'treate" "d 01 a comprising subjecting tung oil to a heatis avoidedvbut it acquires the property of solidifying by prolonged heating-at alower temperature; molding a mixture comp the treated oil com unded with a suitable filling material; an baking the molded article at a temperature below that of the initial heating .to eifect solidification of the treated oil.

3. A method of-making molded articles, which consists in heating tun oil to a rela tivelyhigh temperature w ile avoiding solidification thereof, molding a mixture comprisin the. treated oil compounded'with' a suitable filling material, baking the molded article, and applying thereto an external insoluble coating.

4. A method of making molded articles, which consists in heating tung oil to a relatively high temperature while avoiding solidification thereof, molding a mixture comprisin the treated oil compounded with a suitab e filling material, baking'the molded article, and applying thereto 'an external coating of an infusible and insoluble phenolic condensation product.

5. A method of making molded articles, comprising subjecting tun treatment substantially equivalent to maintaining it at 205210 C. for two and onehalf hours, whereby solidification of the oil is avoided but it acquires the property of solidifying by prolonged heating at a. lower temperature; molding a mixture comprising the treated oil compounded with a suitable material; and baking the molded article at a temperature below that of the initial heating to efiect solidification of the treated oil. '2. A method of .making molded articles,

6. A molded article comprising solidified tung oil and a filling material, said article provided with an external protective coating.

7. A molded article comprising solidified tung oil and a filling material, said article rovided with an external coating of an insible and insoluble phenolic condensation product.

I testimony whereof I afiix my signature.

' LEO H. BAEKELAND.

oil to a heat-f