US2488680A - Method of preparing oxidized - Google Patents

Description

Patented Nov. 22, 1949 METHOD OF PREPARING OXIDIZED I DRYING OIL Izador J. Novak', Trumbull, Conn, assignor to Raybestos-Manhattan, Inc., Passaic, N. J., a corporation of New Jersey N Drawing. Application April 30, 1947,

Serial No. 745,107

This invention relates to a method of reduc-' ing the color formed in an air-blown or oxidized unsaturated vegetable oil when it is subsequently heated to cause it to react, polymerize or harden, and to the product of this method.

It is well known that when pro-oxidized or blown vegetable drying or semi-drying oils are heated above the temperature at which they were oxidized for the purpose of increasing theirbody 0r viscosity, or in making a varnish, the color of the oil deepens markedly. In most cases the darkening is far beyond the color permissible in a varnish or paint vehicle, except for colors 'suchas maroon, green .or black, where the'color of the vehicle is not an important factor. This darkening on heating has therefore largely precluded the use of blown oils in making varnishes where heating is necessary to combine or dissolve resins with the oil. In making a vehicle for a light colored paint, the color of the original blown oil is usually very light, but blown oils without further heat treatment have poor aging qualities when used for this purpose. On the other hand, if the blown oil is heated to 500-600 F., its aging qualities are greatly improved, but the color has been darkened beyond the desirable range.

While the method described hereinafter has usefulness in blown drying oils generally, I have found that it is particularly efiective in the blown oils described in my U. S. Patent No. 2,178,604 wherein the oxidation is carried out at a temperature below the usual range of blown oil manufacturing temperatures. Low temperature oxidation, say below 200 F., results mainly in the addition of oxygen to double bonds and to active hydrogens in the fatty acid chains together with a considerable shift of non-conjugated double bonds to conjugated double bonds. I have found that there is a minor amount of splitting of the chains resulting in the formation of short chain oxidized and unoxidized acids, such as pyruvic, glycollic, capric acids, etc. Oxidation at higher temperatures, such as to about 250 F., also probably results in higher breakdown of the oxidized long chains and distillation or breakdown of the acids formed thereby. Present in all vegetable oils are the natural coloring materials: chlorophylls, xanthophylls, carotenes, etc. These coloring materials also probably are susceptible to oxidation of the same type as the fatty acid chains and to the subsequent breakdown with heat.

One characteristic of the oxidized products above mentioned is a greater or less degree of water solubility. The shorter oxidized chains are 6 Claims. (o1. 260-406) water-soluble, the longer oxidized chains appear to be hydrophilic. v

My invention comprises the water extraction'of the water-soluble (including hydrophilic) materials present in an oxidized drying oil, to produce a new oil free from these Water-soluble or extractable substances. I

When this new oil is bodied by heating it evolves much less gas on heating to higher temperatures, up to say 575-600 F., and results in a bodied oil having a color distinctly lighter than that of the same oil handled in the same manner and carried to the same body but not water extracted. I am aware that water extraction has been widely used to remove dirt, dust, mucilage and the like from raw oils, to remove alkali and soap from alkali-treated oils, or excess acid from acid-treated oils, but it should be notedthat these operations are confined to refining of substantially unoxidized oils. The herein'described method of removing color forming bodies from a highly oxidized light colored oil before bodying so as to obtain the advantage of their absence when the oil is bodied, is new to the best of my knowledge. The results are unexpected in that there is no reason to support that the water-extractable portions of a blown oil include substances which are potential color formers when heated, since the water extract is practically colorless.

The vacuum dehydration of the water extract gives an amber colored residue which is not -ade-' quate to produce the diiference in color'shown by the new extracted oil. The residue darkens onheating in air. However, when the water" extract is remixed with the extracted oil and'the water carefully evaporated from the oil, and the oil is bodied as ordinarily done, the final color is of the same order as that of unextracted oil.

In this connection, water extraction of the refined oil before oxidation has no appreciable effect towards color reduction of the oxidized and 3 On separation, the water layer showed a pH of 2.6 indicating a strong organic acid content. The loss in weight of the oil was 0.25%, representing water-solubles in the oil. The water- 4 From the foregoing examples it is observed that the water extraction of the blown oils mentloned which are characteristic of the classes of drying and semi-drying vegetable oils leaves solubles reduce Fehling solution, indicating alde- 5 oil residues which behave diflerently on heat hydic and/onketonic substances.

The oilllayenafter water extractionwas; heated cautiously at first up to 300 F., to eliminate its water content. It became clear at 275-300 F. On continuing the heating to 575 F., the

bodying temperature, it darkened "less and frothed less than the unextracted oil of the same derivation. It bodied at thewsamezrate ..as--.,the unextracted oil, and reached a Z96 body in approximately one hour at 575 F. The color of the unextracted oil was about 15, n, the Gardner- Holdt scale after bodying in airtoZ-6. ;The color of the water extracted bodied oil was"1'2% after similar treatment. With vacuum rbody-ing.

under a C02 atmosphereg'the color of unextracted oil was; .111, I {that ofthe; extracted aoil .-.1l. ,fIThe bodying time under vacuum was-rconsiderably longer-:about 715/2 =hoursto; Z16.

. Sinceethe wwater extract ,:is acid zit "would .be

expfictedzthatthe acid number ,of ltheextracted goods-explanation.torsthisgphenomenon. .--It,may

be vtha the waterextr ction removes .a fat-- splitting agent which results: in the lower acid content-noted. Whatevertheicausefithe 210W acid number -.-bodied oil ;is-,a -i ery desirable product bodyingathan-athe. unextractedoils in that final color. is: generally reduced and certain. oils show marked reduction in acid content in the bodied sstate.

These improvements were not predictable on -the basis of the prior art since washing unoxidized oils subsequent to standard refining methods ashcwseno comparableeffects.

;:I claimas. myzinyentionz ElJThe method =..:of inhibiting darkening of .-vegetable drying. Oil which has been oxidized by .::,treatmentwith an oxygen-containing gas at a "temperature below 250 F. on subsequent heatingsabove said temperature, which comprises water extracting said oxidized oil prior to said iurther heatin g,,thereof.

.,2.;.The,.proc.ess-. of ,treating unsaturated vegetablel'dryingi oil,,\whi'ch comprises. blowing it .with an. oxy en-containing gas. at. .a.. temp.erature..below 250 F. and extractingit withwater.

3. Ilka-process ,ofitreating unsaturated vegetable drying.,.oil, which comprises treating ,the oil. withranoxygen-containing gas. at a temp eraiiurer below .250.. F... extracting it with "water to remove. potentialcolor forming .materials. thereirom and recovering a treated. oiLcharacterized by reduction .in ,,acid number a and reduction .in color darkening. =and. ..frothing on, ,he atin g. rabove 250 -E.,.,as compa1ted.to alike derived, oxidized andheatedoilin the absenceof saidinterrnediate watenextraction treatmentstep.

.Ah-The -process of. claim: 3 wherein the oil ,is oxidized ata temperaturebelowjw? F.

. 5. \The pmcess .of; .claim. 3 whereinithe. oxidized sincefoilsv with highacidnumbers; are Jess :water-.-. .40 and-Mater extractedoil "is. bodied. by,. heating. to

resistant and-yreactymoreawith pismentsnandgdry 110. 18, slowly-than; those.gwithrloweraacidz numbers; It ;is .=welll-rknown that -lowT H-Cid'gbOdiGdOilS command hisherr emiums in. th i r n z oil markets tha hi hfacidbodied oils.

ow;:temperatur 10W;n refined =-sQyaean-.oi1 handled ii irlthe sa-me; manner as the l-aboves example vand:rina viurn bodi dl'to the rea m de ree sav aacolor; Oil .15. versus.;;18-= f -thercomparame unextracted soya bean oil.

:Asain, irefin d;;1ins d;Loi1-:-b1o\un Ito. J. visco ity at i1240 ,F. ;accordi1 1g:to standard goil blowing practicedos/distinguished from Iow -temperature blow n ,r-afte 'wesh seanchb d in gave a'idisatemperature between 500and600iF.

.6. .The process oi. claim. 3 whereinrthe oxidized and water .extracted-"oil heatedat ,a varnish cooking temperature to .desired varnish oil viscosity.

HIZADORJJ. NOVAK.

REFERENCES ,.CITED ;-The j followingi-references-:areof record: in-the file of this:.patent:

"UNITED? STATES PATENTS Number t n lvrlis t r c lc r than th r nwashe -ioilswheni bodied.

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