US2418454A

US2418454A - Isomerized fatty acid esters

Info

Publication number: US2418454A
Application number: US611269A
Authority: US
Inventors: Auer Laszlo
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-08-17
Filing date: 1945-08-17
Publication date: 1947-04-08
Anticipated expiration: 1964-04-08

Description

metal hydroxides.

Patented Apr. 8, 1947 Laszlo Auer, South Orange, N. J.

N Drawing. Application August 17, 1945;

Serial No. 611,269

20 Claims.

GENERAL FIELD or Invunnon AND STATEMENT or Gamers This invention relates to the isomerization of fatty acids and to esters of such fatty acids. Its object is to increase the number of conjugated double bonds in the fatty acid chain, when compared with the conjugated double bond content of the fatty acids before treatment in accordance with the present invention.

The fatty acids treated according to this invention are the acids found in natural fats and fatty oils, It is known that esters of fatty acids, having conjugated double bonds, dry faster when used in coating materials, such as varnishes and paints, than esters of fatty acids having only isolated double bonds. The esters of fatty acids. having conjugated double bonds in the fatty acid chain are also known to body faster at heat bodying or varnish cooking temperatures.

Examples of esters of fatty acids with conjugated double bonds are: tung oil, oiticica oil and dehydrated castor oil. Esters of fatty acids with isolated double bonds are for instance: linseed oil, soyabean oil, perilla oil, fish oils, and others.

Whereas fatty acids may form esters with monohydric or dihydric alcohols, for the purposes of coating materials esters of polyhydric alcohols are preferred, having at least three hydroxyl groups in the molecule, such as glycerine, pentaerythritol, sorbitol, mannitol, amongst others.

The object of this invention is to isomerize the fatty acids of drying and semidrying oils, which have at least two double bonds in the molecule, such double bonds being in an isolated position. By such isomerization the double bonds are rearranged and instead of being in an isolated position, they are in conjugated position.

Such isomerization has been done in the past using solutionsof alkalies, such as alcoholic solutions of alkali metal hydroxides or of alkali metal acoholates, or aqueous solutions of alkali The fatty oils, fatty acids or in general, the esters of the fatty acids to be isomerized are heated with such solutions of alkali metal hydroxides or alkali metal alcoholates. Soaps are formed and after the treatment is completed, the soaps are converted into the fatty acids, which may be esterifled in another step. In all such isomerization processes excess alkalies are necessary, 1. e. a larger quantity of alkaline agent, than necessary to neutralize the fatty acids and convert them completely into soaps.

According to my copending application Serial No. 601,725, filed June 26,1945, isomerization of fatty acids occurs if fatty acids or their esters or compounds containing fatty acid radicals in a form that fatty acids may split off during the reaction, are heated with anhydrous alkali metal oxides or hydroxides or free alkali metals to temperatures exceeding C. and not exceeding 350 C. or the decomposition temperatureof the product, whichever is lower. carbonates may also be used.

In Patent 1,957,437 applicant has disclosed his anhydrous saponification method. Similar subject is disclosed in Ser. No. 455,131, filed August 17, 1942, now Patent2,382,530, and in Ser. No. 455,132, filed August 17, 1942, how Patent 2,382,531. The present specification is a continuation-impart of my application Ser, No. 601,725, which in turn is a continuation-in-part of the last two mentioned patents.

According to this invention only the smaller portionof the fatty acids of the fatty material is converted into an anhydrous soap. The anhydrous soaps are formed between C. and 350 C, by the addition of an anhydrous alkali agent to the fatty material. The quantity of the alkali agent is enough to convert the equivalent of at least 5 and not more than about 60 saponification number units into soaps, The soap containing fatty material is dispersed in water, the soap is split and the soap-free fatty material is separated and recovered. The so-treated fatty material may be used as SUCIL'OI may be used after re-esterification of its free fatty acid content, or it may be freed from its fatty acid content by distilling the fatty acids out of the ester portion of the fatty material. I

The present invention is a further improvement of the earlier copending process of applicant and its main characteristic is, that only a comparatively small portion of the fatty acids is converted into soaps and therefore it is not nec essary to split and recover all the fatty acids and to re-esterify the entire fatty acid content in the last leg of the process.

has been found. that so: and ms gas or 3 a mixture of both very favorably accelerates the isomerization process according to this invention.

a It is further advantageous to evolve these gases i ilssitu during the reaction. If alkali sulfides or sulfites are used as alkali agents in this process, theyf'evolve H28 and S02 gas in situ in the reaction chamber.

According to this invention fatty materials comprising" fatty acids with isolated double bonds are converted in part into soaps by an anhydrous saponification method. The soaps are formed by the fatty acids of the fatty material on one end and by an anhydrous alkali material on the other end upon the action of heat. Such anhydrous alkali materials are alkali metals, their oxides, hydroxides, carbonates, sulfides or sulfites. The heating is carried out between 150 C. and 350 C. but not above the boiling or decompo sition point in the fatty material, the heating being for at least 30 minutes, and until upon cooling to room temperature a solid fatty material is formed. During this process the fatty acids isomerize and the isolated double bonds rearrange into conjugated double bonds, at least in a considerable proportion. The conjugated double bond content of such fatty acids is thereby increased. The soap containing fatty materials so formed are dispersed in water, forming therein a colloidal dispersion. The soap is then split and the fatty acids are freed by acidifica tion of the aqueous dispersion. Such acidification separates the fatty acids and also the esters of fatty acids, which did not convert into soaps during the process. The metal constituent of the soap remains dissolved in the water phase of the mixture in form of a metal salt of the acids used for acidification and the fatty material com prising the fatty acids with improved drying properties and increased conjugated double bond content are then separated, washed and dried. For many purposes the fatty material so obtained may be used as such with its free fatty acid content. However, an improved material may be obtained for many other purposes if the free fatty acids are re-esterified with polyhydric alcohols, to form esters useful in coating materials. In another alternative the free fatty acids may be removed, for instance by distillation.

FATTY MATERIAL The invention is applicable generally to fats and fatty oils comprising fatty acids with isolated double bonds, a typical list of fatty oils being asfollows:

Tung oil Oiticlca oil Dehydrated castor oil Linseed oil Poppyseed oil Soyabean oil Walnut oil Rapeseed oil Pine seed oil Olive oil Corn oil Cottonseed oil Coconut oil 'Hydroxylated oils such as castor oil, etc. Fish oils (train oils) Acids of any of the above oils.

From the list it will be seen that not only drying oils are suitable, but also semi-drying and non-drying oils. The fatty acids of these oils may also be used and the starting material may consist of a single oil or fatty acid or mixtures thereof. Fats may also be present in addition to the above oils.

Fats and non-drying oils are suitable for the instant process insofar as they contain fatty acids with isolated double bonds.

Oils which contain already conjugated double bonds in their fatty acids, may be used as starting materials of this process insofar as they contain also fatty acids with isolated double bonds.

Still further, the invention is adapted to the treatment of other raw materials such as fatty waste material, for instance, fatty acid distillation residues, foots, such as mucilaginous matter, and other byproducts of fatty oil refining (sludges).

It is .here pointed out that the expression fatty materials" as used herein; including the claims appended hereto, comprehends various of the oil and fatty materials of the types mentioned above, all of which contain fatty acids with at least two double bonds in the molecule, said double bonds being in isolated position.

ALKALI AGENT The alkali agents may be alkali metals, alkali metal oxides or alkali metal hydroxides, or alkali metal carbonates or alkali metal bicarbonates. Alkali metal sulfides, sulfites, bisulfides, bisulfites and hydrosulfites may also be used as alkali agents, as they form metal oxides or hydroxides in situ during the reaction.

.With reference to the metals, it may be mentioned that lithium, sodium and potassium are well suited for this process. Ammonium is also herein classed with these metals, since the action thereof is similar to the alkali metals.

Using chemically equivalent quantities, compounds of lithium will normally produce the hardest soap containing products, other treatment conditions being equal. Compounds of sodium, potassium and ammonium yield progressively softer soap containing products in the order listed, although all are capable of producing a solid soap containing product (solid when cooled to room temperature). The alkali agents may be used separately or in admixture with each other. For most purposes hydroxides or carbonates of sodium are preferred since they are not only readily available but, also capable of producing a soap containing product of good hardness. However, good quality materials may be obtained also by using other alkali materials such as, potassium compounds.

In the event alkali metals are used as alkali agents, hydrogen is being formed during the reaction and proper precautions are required.

ANHYDROUS SOAP FORMING Pxocnss and/or time increases the hardness of the product. In any event for the purpose of producing the solid soap containing materials, herein contemplated, the treatment temperature and time should be such as to drive off most or substantially all of the water formed during the process.

The quantity of alkali agent should preferably, according to this invention, be so much that the anhydrous soap formation should account for a reduction of at least'5 and notmore than 60 units of the saponification number of the fatty material. The exact quantity of alkali agent required will vary, depending upon the result and change desired.

In the present process a partial soap forma-' tion occurs and the major part of the fatty acids remain in the form of esters, or remain free of soap formation. To illustrate the proportion of soap formed, it maybe mentioned, that free fatty acids have saponification numbers just above 200, whereas the saponification number of fats and oils is generally in the neighborhood of 190. Therefore, the portion of fatty acids converted into soap, according to thisprocess, is in maximum not more than slightly above one quarter of the fatty acid content available, providing that natural fatty oils or'their acids are treated.

Preferably the alkali agent shouldbe used in anhydrous form, that is free of crystal water.

During the soap formation, as'is mentioned more fully hereinafter, and also as illustrated in the examples, the reaction mass may be placed under vacuum. This is of advantage in many" instances in order to reduce contact pf'the air with the reaction mass. Other means may be employed for this purpose, for instance, the reaction may be. carried out in a vessel having only a small outlet to the atmosphere, CO2 released during the reaction from a carbonate used as alkali agent being relied upon to exclude the air.

Generally speaking to preserve light color of the product, I found that keeping the reaction mixture out of contact with the atmosphere is of.

advantage. Light colored soaps will yield light colored fatty acids and esters of fatty acids. Therefore it is advantageous to blanket the reaction mixture with an inert gas or pass the gas through the reaction mixture. Besides CO2, nitrogen, H251 and S02 may be used, amongst others. I found that S02 and Has are 'promoting isomerization. These gases may be introduced into the reaction vessel from the outside or may be evolved in the reaction mixture by employing salts containing them, such as sulfides and sulfites.

The product containing the soap is a bad heat conductor and therefore partial overheating may occur at certain spots. Such overheating causes charring and darkening of the product. Proper agitation and engineering precautions may help to solve this difficulty. I have found that addi tion of rosin to the reaction mixture acts as a fluxing agent and promotes light color of the product obtained. Usually 5 to 20% rosin based on the fatty material is sufllcient for the purpose. The addition of rosin also assists reduction of foaming. If rosin is used larger quantities of alkali agents may have to be used, to convert the rosin acids also into soaps.

Still further, supplemental conditions and/or treating agents may be employed during the formation of the anhydrous soap containing product, but many of these have direct bearing on the process steps of the present invention and these are, therefore, considered more fully hereinafter.

DISPERSIN'G rm: SOAP CONTAINING Pnonuor IN WATER AND Acmrrrmo rm: Warns DISPERSION .free the fatty acids of the soap. As the. fatty material, according to this process is; only partially saponified, unsaponified esters remain in the product and the fatty acids so separated contain also the unsaponified fatty material.

For the purposes of acidification'any acid may be used, which is able to split the soap containing water dispersions. For the most purposes sulfuric' acid or hydrochloric acid may serve well.

After the acidification is completed, the fatty material is separated from the water phase, washed and dried. The separation may be carried out by decantati'on, but the addition of water immiscible organic fat solvents may be of additional advantage.

The free fatty acids may be left in the product and the soap-free treated fatty material may be used for many purposes with its free fatty acid content.

For other purposes, and especially, if the free fatty acid content is high, esterification, i. e. re-esterification of the free fatty acids is desirable. For uses in protective and decorative coatings, polyhydric alcohols having at least 3 OH- groups are desirable. Glycerine, pentaerythritol and sorbitol are examples. Some polyhydroxyphenols may be used for the esterification of the free fatty acids such as resorcinol and pyrogallol.

The products obtained after the re-esterification is completed, may be used per se in coating materials, or may be cooked into varnishes and used in that form. In another alternative of the process the free fatty acids may be distilled off from the unsaponified fatty material and the two components may be used separately. It is one of the characteristics of this process, that the isomerization does not occur only in the fatty acids which take part in the soap formation, but that the unsaponified fatty acids and their esters are also improved for the purposes of their use in paints, varnishes and other coating materials. The distilled fatty acids may be re-esterified, or used in or anhydrides may be present, to form mixed esters of the alkyd resin type. Examples are maleic anhydride, phthalic anhydride, sebacic acid, Petrex, which latter is an adduct of maleic anhydride formed with terpene hydrocarbons, etc.

The steps' of dispersing the soap containing product in water, acidification, separation of the isomerized fatty material, washing and drying of said material and the esterification of same, if any, may be better described in the form of examples.

ILLUSTRATIVE EXAMPLES For the purpose of illustrating the process, the following examples are given with the under standing that the scope of this invention should not be limited to these examples.

Example 1.--1,000 grams of alkali refined linseed oil were heated in a 5 liter 3-neck flask. In the center neck of the flask an agitator was placed. One of the side necks carried the ther m'ometer, which emerged into the oil and the same neck had a gas inlet, through which a gas could be introduced into the reactor (flask). The

other side neck connected the flask with a receivlng bottle which collected easily condensed distillates and also served to catch foamed over reaction mixture. 50 grams oi sodium bisulfite was added to the oil, representing of the weight of the oil and the reaction mixture was heated to 285 C. and kept there for 5 hours. The 3 neck flask through the receiving bottle was connected with a vacuum pump and the gas atmosphere above the reaction mixturein the 3 neck flask was kept constantly at 400 mm. pressure, representing a moderate vacuum. During the reaction, most of the S02 content of the sodium bisulfite was given ofi and the evolved gas left the reaction mixture. A sodium soap was formed by the NaOI-I, formed from the sodium bisulfite, on one end, and the linseed oil fatty acids on the other end. The product obtained after the 5 hour heating at 285 C. was a solid soft product, when cooled to room temperature. The same product at the reaction temperature was a viscous but liquid material.

The soap containing product so obtained was emulsified by water, using times as much water by weight, as the weight of the soap containing treated material. To obtain the aqueous dispersion (emulsion) the water was heated to its boiling temperature and the soap containing oil product was heated to a temperature at which it was fluid. About 100-120" C. is usually satisfactory for this purpose. The oil and the water were mixed together under agitation. It is possible to add the oil to the water, but for most purposes it may be advantageous to add the water to the oil, providing the temperature of the oil is not too far above the boiling point of water.

After a uniform aqueous dispersion has been obtained, dilute sulfuric acid was added in a quantity required to bring the aqueous mixture permanently to the acid side. At this stage a water immiscible organic fat solvent is added, such as petroleum ether, or toluol, or carbon ",tetrachloride and the organic solvent solution is separated from the water solution, repeatedly washed until the wash water was free from sulfate ions, dried from,water and the resulting soap-free fatty material was recovered by disheated with glycerine under reflux at a temperature of 230 C. with so much glycerine, that the weight'of the glycerine was about 10% of the weight of the free fatty acid content of the product of Example 1. This free fatty acid content corresponds approximately to about -21% of the product of Example 1, in view of the acid value of 40.8, and of the fact that the acid value of free fatty acids is about 200. During the reesterification process 400 mm. vacuum was maintained over the reaction mixture. Calcium oxide was used as esterification catalyst in the amount of-0.1%, based on the fatty material treated. The esterification was completed in about 5 hours time and if the product was kept for 5% hours at the esterification temperature a solid gel was obtalnedat the reaction temperature.

Some portion of the product of Example '1 was left in its original condition for some of the ex amples further below.

Example 3.200 grams of the product of Example 1 were heated in a 1 liter aluminum beaker with 100 grams of ester gum, to yield an approximately 25 gallon long varnish. The mixture of the oil and resin were heated to 300 C. and kept at that temperature until they yielded varnish solids, which when diluted with mineral spirits to 50% non volatile content, had a. viscosity of C to H on the Gardner scale. The mixture treated in this example yielded a viscosity G after 125' of cooking.

Example 4.-Using the product of Example 2, a similar varnish was cooked as described in Example 3. The cooking time was 180 and the viscosity was B at 50% non volatile content.

Example 5.Example 1 was repeated with the only difierence, that sodium sulfide was used in an equivalent quantity to the sodium bisulfite of Example 1. 13.5% crystalline sodium sulfide were used. The cooking temperature and cooking time and the vacuum were the same as in Example 1, so were other reaction conditions. The solid soap containing product was dispersed in water, acidified, washed and separated,'in a, similar way as described in Example 1. The resulting product had an acid value of 29.3, saponification value of 190.5, and an iodine value of 129.3.

Example 6.-The free fatty acid containing product of Example 5 was re-esterified in the manner described in Example 2. After 5 hours of heating at 230 C., as described in Example 2, a viscous oil resulted with an acid value of 17.1.

Example 7 .An approximately 25 gallon long ester gum varnish was made out of the product a of Example 5, in a manner as described in Example 3. The heating time was 200 and the viscosity at 50% non volatile content was D.

Example 8.--An approximately 25 gallon long ester gum varnish was prepared of the product of Example 6, in the same manner as described in Example 3. The heating time was 190', but the viscosity at 50% non volatile content was only A.

Example 9.-Example 1 was repeated with an equivalent quantity of sodium hydrosulfite, to replace the 5% sodium bisulfite of Example 1. The required quantity was 13.7%. The sodium hydrosulfite used had two molecules of water of crystallization. Proceeding in the same way as described in Example 1, the final product, free of soaps, was a viscous oil, having an acid value of 46.5, a saponification value of 189.6, and an iodine value of 95.5.

Example 10.A portion of the product of Example 9 was re-esterified in the manner described in Example 2. After 9 hours of heating the acid value dropped to 8 and the product was a viscous oil. The esterification time in this example was longer than in Example 2.

Example 11.-An approximately 25 gallon ester gum varnish was cooked out of the product of Example 9, in a manner as described in Example 3. The cooking time was and the viscosity was slightly higher than A, when thinned to 50% non volatile content.

Example 12.--An approximately 25 gallon ester gum varnish was cooked out of the product of Example 10, in a manner as described in Example 3. The cooking time was 180 and the viscosity was slightly higher than A, when thinned to 50% non volatile content.

Driers were added to thevarnishes of experiments-3, 4, 7, 8, 11, and 12, to yield 0.03% cobalt metal, 0.3% lead metal and 0.02% manganese metal, based on the oil content. The'drier containing'varnishes of Examples 3, 4, 7, 8, 11, and 12 have been tested on drying time, alkali resistance, cold water resistance and hot water resistance.

The state ofthe films was evaluated according to the, standards, as described in the Oflicial.

Digest of the Federation of Paint & Varnish Pro.-

All films were deposited with'a' Bird filmsap+ plicator to yield .0015" wet film thickness; Print. condition was only measuredon films which were.

more advanced than the best stage (E) In asured' under the heading of Film condition or t rough' drying. H

Table 1 1 Sodium Hydrosulfite Sodium Bisulfite Example No. 11 i2 (Acidic) (Ester-med)...

Dust Free lhru llihrsldhrsn -6brs.

S t a g e Reached.

State of Film A f t c r 7 hours.

State of Film After Overnight Drying.

With 48 hour old films, deposited in 0.003" wet film thickness, alkali resistance tests were carried out and it was found that most of the varnishes resisted 3% NaOH solution for longer than 7 hours and the varnish of Example 7 was resistant even after 24 hours immersion.

Th resistance to cold water and to boiling water was also tested and the products of varnishes of Examples 7 and 8 were most satisfactory in the water tests, whereas the products of Examples 11 and 12 followed next.

In another set of experiments, cold out varnishes were prepared in a similar manner to'the constitution of varnishes of Examples 3, 4, 7, 8, l1, and 12, with the only exception that the varnishes were not cooked but the ingredients were mixed in the cold, using an ester gum solution.

in mineral spirits. From these cold cut varnishes especially fast drying products were obtained in formulations similar to Examples 7 and 8, using the oils treated with sodium sulfide.

In the above examples other oils, such as soyabean oil and dehydrated castor oil may be sub stituted for linseed oil, other alkali agents for the ones used; and other reaction conditions maybe,

materials being, however, the common characteristics of the products of the various alternatives of this process.

Immovsn Arrrnmrrvs laocsss It has been found, that if agents are added to the soap containing treated fatty products, which form with the alkali ion of the soap and oil-insoluble salt, it is possible to form such salt in the oil as a precipitate. without necessitating the following steps: dispersing the soap containingfatty oil products inwater, acidifying water dispersion, washing and drying In other words all these latter steps could be eliminated.

The oil-insoluble alkali salts could be either left in the oil mixture, or could be removed by filtration or by centrifuging.

Examples are phosphoric acid or pyroantimonic acid oragents producing such acids in situ in. the reaction mixture.

-I claim:

1. In the process of producing a composition of matter comprising fatty acid esters with improved drying properties, the combination or steps of (1) forming an ,anhydrous soap by heating a fatty material comprising a polyunsaturated fatty acid with a substantially anhydrous alkali agent at temperatures ranging from 150 C. to about 350 C. ,but not higher than the boilingpoint or decomposition point of the fatty material, whichever is lower,for at least one half hour and until a portion of the fatty acids is converted into a.

soap, showing a decrease of saponiflcation number of at least about 5 and not more than about 60 units, and until the resulting product is solid at room temperature, said alkali agent being enough to convert the equivalent of at least 5 and not more than about 60 saponincation number units into a soap. (2) splitting the so formed soap and (3) separating the unsaponifled fatty mate- 1 rial and the fatty acids which formed the soap from th cations of the soap and recovering the mixtureof theunsaponified fatty material and of the free fatty acids.

2. The process of claim 1 wherein in a further step the free fatty acids of the product are esterifiedwith a polyhydric alcohol.

3. The process of claim 1 wherein in a further step the free fatty acids of .the product are distilled on? and recovered.

4. The process of claim 1 wherein the temperature of soap formation is between 250 C. and 300 C.

5. The process of claim 1 wherein the pressure in the reaction vessel is kept below that of atmospheric.

6. The process of claim 1 wherein the pressure in the reaction vessel is kept above that of atmospheric.

7. The process of claim 1 wherein in a further step th free fatty acids of the product are esterified with a member of the class consisting ofresorcinol and pyrogallol.

8. The process of claim 1 wherein S02 gas is present in the reaction vessel during the reaction.

9. The process of claim 1 wherein HzS gas is present in the reaction vessel during the reaction.

10. The process of claim 1 wherein S02 gas and H28 gas are simultaneously present in the reaction vessel during the reaction.

11. The process of claim 1 wherein the alkali agent is a, sulfide.

12. The process of claim 1 wherein the alkali agent is a sulfite.

11 13. The process of claim 1 wherein the alkali agent is sodium bisulflte.

14. The process of claim 1 wherein the alkali agent is sodium hydrosulflte.

- 12 unsaponifled fatty material and the fatty acids from the mother lye; i

20.' The process of claim 1 wherein the splitting of the soap is carried out by adding an agent 15. The process oi claim 1 wherein the alkali 5 to the anhydrous treated fatty material, which agent is sodium sulfide. v

16. The process of claim lwherein the i'atty material is linseed 01L 7 17. The process of claim 1 wherein the fatty material is a castor oil.

18. The process of claim 1 wherein the fatty material is soya-bean oil.

19. The process of claim 1 wherein the splitting of the soap is carried out in an aqueous mediu and an organic water immiscible-fat solvent is added to the aqueous mixture after the splitting of the soap, to aid the separation 01' the 15 Number- REFERENCES CITED The following references are of record in the file of this patent-:

' UNITED STATES PATENTS Name Date 2,389,260 Kirschenibauer Nov. 20, 1945