US2381888A

US2381888A - Process of making mixed esters

Info

Publication number: US2381888A
Application number: US441225A
Authority: US
Inventors: Agre Courtland Le Verne
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1942-04-30
Filing date: 1942-04-30
Publication date: 1945-08-14
Anticipated expiration: 1962-08-14

Description

Patented Aug. 14, 1945 UNITED STATES PATENT OFFICE PROCESS OF MAKING MIXED ESTEBS No Drawing. Application April 30, 1942, Serial No. 41,225

'2 Claims.

This invention relates to the preparation of synthetic drying oils and, more particularly, to a process for the preparation of polyhydric alcohol mixed esters of natural oil fatty acids and certain unsaturated monocarboxylic acids.

The higher grade natural drying oils, such as China-wood oil, perilla oil, and oiticica oil, are outstanding in their ability to rapidly form hard, tack-free, water-resistant films when properly formulated into varnish and enamel compositlons. However, these oils are for the most part imported and are subject to wide fluctuation in price, quality, and availability.

Recent research has shown that synthetic polyhydric alcohol mixed esters of natural oil fatty acids and certain unsaturated monocarboxylic acids (which are readily available or may be prepared from readily available intermediates) possess drying properties equal to, and in some instances superior to, those of the natural tastdrying oils.

The usual procedure for the preparation of mixed esters of natural oil fatty acids and these synthetic monocarboxylie acids, such as p-iurylacrylic acids, has involved a. two-step process in which a partial ester 01' the fatty acids and polyhydric alcohol is first formed, for example, by reacting the natural oil with a polyhydric alcohol to give the alcoholized oil (such as a mixture of mono-, di-, and tri-glycerides), which is then treated with free monocarboxylic acid to give the mixed ester. This process has the disadvantage of requiring several steps, and in many instances the color is darker and the viscosity higher than is desired.

It is a general objective of this invention to provide a new and improved process of making synthetic drying oils.

Another objective is the preparation of synthetic drying oils of improved color and lower viscosity.

A more particular objective is to provide a. single step process for preparing synthetic drying oils from natural fatty oils, polyhydric alcohols, and certain kinds of unsaturated monocarboxylic acids. of which hexadien-2,4-oic and i'urylacrylic acids are typical.

The above and other objects appearing hereinafter are accomplished by the direct interaction of a naturally occurring glyceride with an essentially stoichiometric mixture 01' polyhydric alcohol and rip-unsaturated monofunctional monocarboxylic acid.

The term "an a e-unsaturated monoiunctional monocarboxylic acid is used in a generic sense to mean any monofunctional monocarboxylic acid having an ethylenic double bond between the a and 5 carbon atoms.

The term monofunctional means that the monocarboxylic acid contains no group capable of undergoing reaction with the single carboxyl group under normal esterification conditions; i. e., acids having such groups as OH, SH, NH-z, or NHR would not be suitable.

The products of this invention are in no way similar to mixtures of the fatty oil with, e. g., the triglyceride of the pt-unsaturated monofunctional monocarboxylic acid. Such mixtures, e. g., of linseed oil and p-(2-iuryl) acrylic triglyceride, are non-homogeneous and devoid of any known utility.

As indicated above, the general process of this invention is the simultaneous reaction of one or more natural fatty oils with one or more polyhydric alcohols and one or more cap-unsaturated monofunctional monocarboxylic acids. The latter acid is preferably one which contributes substantially toward improved drying properties. The fatty oil is preferably a drying or semi-drying 011, although the process is equally applicable to the production of mixed esters of non-drying oils, such as coconut oil and corn oil.

The process may be carried out either by fusion Or solution procedures. In one of the preferred methods of carrying out the invention, a natural oil and a stoichiometric mixture of polyhydric alcohol and a,s-unsaturated monofunctional monocarboxylic acid are charged, along with a small amount of esteriflcation catalyst (such as 01-05% sodium hydrogen sulfate, based on the acid), into a. reactor having three openings into which are fitted an agitator, a thermometer or other device for measuring temperature, and a as inlet tube. A hydrocarbon solvent, such as xylene or toluene, is introduced in suflicient amount to produce boiling at a temperature of about 200 C. The distilled vapors of solvent and water of esterification are condensed, the water separated mechanically, and the solvent returned to the reaction vessel in a continuous manner. Reaction is usually complete in 4-16 hours, depending upon the reaction temperature and the amount of esteriflcation catalyst employed. At a temperature of 200 C., using about 0.3% sodium hydrogen sulfate monohydrate as catalyst, the reaction is complete within 4-8 hours. The progress of the reaction may be followed by determination of the amount of water evolved or, more accurately, by acid number determinations, the heating being stopped when the acid number reaches constancy or the value desired. The solvent may be removed by distillation or by blowing the product with an inert Has. which procedure will also efiect a partial removal of unreacted unsaturated acid, or of natural oil fatty acids released during the reaction.

The following examples illustrate the detailed practice of the invention. More particularly, they show the production of improved synthetic drying oils through use of typical nip-unsaturated monofunctional monocarboxylic acids, and the formulation of such oils into coating compositions. In these examples, amounts of the ingradients are by weight; viscosities are in noises; colors are on the Gardner-Holdt scale; and the hydroxyl numbers are corrected for acidity; and, when cobalt drier is mentioned, sumcient of a 2% cobalt naphthenate solution is used to give the indicated content of cobalt metal, this proportion being based on the oil.

The ester compositions in the titles of each example do not mean th product actually contains the stated percentages of triglyceride, but are instead an index to the proportion of monocarboxylic acid radicals in the product. To illusstrate, a product referred to as having 20.4% afiunsaturated monofunctional monocarboxylic acid glyceride and 79.6% linseed acids glyceride is a product prepared from proportions of reactants so chosen as to yield theoretically a mixture of the two mentioned glycerides in the stated proportions by Weight. Actually, such a product is consldered to be composed principally of mixed glycerides, probably mixtures of mixed glycerides, though small amounts oi simple glycerides, partial glycerides (i. e., glycerol incompletely esterified), free glycerol, and free acids are probably present. The significance of the a,,8uns&tllrated monoiunctional monocarboxylic acid ester content is discussed following the examples.

EXAMPLE 1 Glycerol mixed ester of linseed oil acids and ,8-(2- juryllacrylic acid Percent p- (Z-iuryl) acrylic acid glyceride 20.4 Linseed acids glyceride 79.6

Two hundred eight (208) parts of alkali-refined linseed oil, 11.1 parts of highly refined glycerol, 49.2 parts of fi-(Z-furyl) acrylic acid (of M. P. 140- 141 C. (Gibson and Kahnweiler, Am. Chem. Journ. 12, 314 (1890)), and 0.25 part of sodium hydrogen sulfate monohydrate (ground into the p-(Z-iuryDacrylic acid) are heated in the presence of 10 parts of toluene at 200-225" C. under an atmosphere of carbon dioxide. The toluene and water, which distill, are condensed, the water separated and the toluene returned to the reaction vessel. Heating is continued for 5 hours and the product is then blown with carbon dioxide for about 0.5 hour to remove toluene (a small amount of unreacted ,5-(2-furyllacrylic acid is also removed by this operation). After cooling to 100 C., the product is filtered and has the following physical and analytical values: N 1.4997; (14 0.9802; hydroxyl No. 2.1; iodine No. 185.4; saponification No. 216.7; acid No. 3.2; viscosity 1.0; color 4.2.

With 0.03% cobalt, this product air-dries tackfree over steel or wood in about 8 hours to films which are clear, smooth and glossy, and show excellent flexibility, toughness, and hardness.

Films having similar properties can be obtained in a shorter time by baking at C. Attractive films can also be obtained on other substrates, such as silk or paper.

This oil shows almost exactly the same analytical properties as one prepared by first reacting the linseed oil with glycerol to form linseed diglyceride, followed by esteriilcation of the diglycerlde with fi-i'urylacrylic acid. However, the oil prepared according to the present invention has a lower viscosity, making it more applicable to preparation of enamels having high solids, such as metal protective paints, where the excellent drying and hardness of these oils are desired along with the best possible coverage. The color is also lighter, a factor of obvious importance for applications in tinted and light-colored coating compositions, such as that shown below.

A typical white enamel can be prepared by grinding in a ball mill, for 4 days, 22 parts or the above mixed glyceride, 50 parts of titanium dioxide, 50 parts of antimony oxide, and 24 parts of mineral spirits, and blending the grind with 78 additional parts of the mixed glyceride, 20 parts of mineral spirits and 0.03% cobalt. This enamel dries in 12-14 hours at room temperature over steel, wood, or other surface to films superior in hardness to those of a control enamel prepared from a 45-gallon China-wood oil/limed-leaded rosin varnish of viscosity 2.25 at 50% solids in mineral spirits.

A black enamel can be prepared by grinding 20 parts of carbon black with 100 parts of the above 011 and thinning with 20 parts of mineral spirits in the presence of 0.03% cobalt. This enamel dries overnight at room temperature to hard, tough, tack-free films over either bare steel or wood. Baking at elevated temperature (for example, 100 C.) gives much more rapid set-up.

EXAMPLE 2 Glycerol mixed ester of lrinseed oil acids and s- 2- furyl) acrylic acid-Fusion method Percent ,B-(Z-i'uryl) acrylic acid glyceride 20.4 Linseed acids glyceride 79.6

A stainless steel kettle equipped with stirrer,

thermometer, gas inlet tube, and exit tube for the escape of water is charged with 4770 parts of alkali-refined linseed oil, 253 parts of dynamitegrade glycerol, 1133 parts of fl-(Z-furyllacrylic acid, and 9.6 parts of an aqueous solution containing 2.4 parts of sodium hydrogen sulfate monohydrate. The temperature is maintained at 200 C. for 1 hour with a moderate inert gas blow to facilitate removal of the water formed. The temperature is then raised to 225 C. and held at this point until the acid number has reached 11, the gas blow being increased slowly during this period. The product is then blown vigorously with inert gas for a period of 0.5 hour. After cooling to room temperature and centrifuging, there is obtained 5868 parts of oil having the following physical and analytical values: Acid No. 8; viscosity 4.35; color 6.2.

Twenty (20) parts of the above oil and 10 parts of a 64% solution of limed rosin in mineral spirits are stirred together until a homogeneous mixture is effected. With 0.05% cobalt, this blend becomes tack-free in 6-7 hours at room temperature, giving extremely hard, glossy films after overnight drying which show no tendency to frost-II EXAMPLE 3 Glycerol mixed ester of 8011!! been oil acids and p- (Z-furyl) acrylic acid A mixture of 1800 parts of refined soya bean oil. 1648 parts of fl- (2-furyl) acrylic acid, 366 parts of refined Glycerol, and 7.0 parts oi an aqueous solution containing 4.9 parts of sodium hydrogen sulrate monohydrate is maintained at 200-225 C. for 3 hours in an atmosphere of deoxidiaed nitrogen. The water which is formed is removed as a binary with toluene, the water being separated out on condensation and toluene returned to the reaction vessel. After being blown with a rapid stream of deoxidized nitrogen for 1 hour at 220 C., the product is cooled to approximately 100 C. and filtered. A clear, high viscosity, oil of acid number 7.6 and'a viscosity above 150 is obtained. It is compatible with an equal weight of unbodied soya oil; the mixture with added cobalt dries slowly at room temperature to a tough, hard, tackfree film. n adding further quantities of soya bean oil (3 parts of soya bean oil to 2 parts of the oil), the mixture becomes incompatible.

Exams: 4

Glycerol mixed ester of linseed oil acids and hexadien-2,4-oic acid A mixture of 100 parts of alkali-refined linseed oil, 128 parts of hexadien-2,4-oic acid (Doebner, Ber. 33', 2140 (1900)), 35 parts of glycerol, and 0.13 part of sodium hydrogen sulfate monohydrate is heated at 200-210 C. for 6 hours under an atmosphere of carbon dioxide, the water being removed as in Example 1. After blowing with deoxidized nitrogen, cooling, and filtering, the blown oil has the following physical and analytical values: hydroxyl No. 9.3; acid No. 6.1; viscosity 1.0; color 3.3. With 0.03% c balt. the oil dries tackfree in about 8 hours at room temperature, giving clear, glossy and hard films possessing excellent color.

Exam ne Glycerol mixed ester of corn oil acids and p- 2-furyl) acrylic acid Percent B-(2-furyDacrylic acid glyceride 20.0 Corn acids glyceride 80.0

A mixture of 200 parts of corn oil, 46.4 parts of B-(Z-furyl) acrylic acid, 11.3 parts of refined glycerol, and-0.2 art of sodium hydrogen sulfate monohydrate is heated at 200-205 C. for 6 hours in an atmosphere of carbon dioxide, the water being removed with toluene as in Example 1.- After being blown with carbon dioxide for 0.5 hour at 200 C., the oil is cooled to 100 C., and filtered. At room temperature, the oil has the following physical and analytical values: N 1.4953; hydroxyl No. 6.9; acid No. 3.1; viscosity 1.25; color 4.2.

EXAMPLE 6 Glycerol mixed ester of linseed oil acids, soya been oil acids, and B- (z-juryl) acrylic acid Soya bean acids glyceride A mixture of 177 parts of soya bean oil, 31 parts 0! linseed 011, 54.1 parts 01' ,B-(Z-furyl) acrylic acid. 11.0 parts of refined glycerol, and 0.05 part of sodium hydrogen sulfate monohydrate is heated at 200.225 C. for 5 hours in the presence of an inert gas, the water being removed with toluene as in Example 1. The product is blown for 0.5 hour at 200' C. with inert gas, cooled to C., and filtered, giving an oil with the following physical and analytical values: hydroxyl No. 2.9; acid 7.4; viscosity 1.4; color 3.7. With 0.03% cobalt, this oil dries tack-free at room temperature in about 3 days.

Emmet: l

Glycerol mired ester of linseed oil acids, Chinawood oil acids, and p-(Z-iuryl) acrylic acid Percent p-(2-furyl) acrylic acid glyceride 20.6 Linseed acids glyceride 67.6 China wood acids glyceride 11.8

A mixture of 177 parts of alkali-refined linseed oil, 31 parts oi China wood oil, 54.1 parts of p-(2- luryhacrylic acid, 11.0 parts of dynamite-grade glycerol, and 0.05 part of sodium hydrogen sulfate monohydrate is heated at 200-225 C. for 5 hours in an atmosphere of carbon dioxide, water being removed as in the previous examples. The prodnot is blown for 0.5 hour with oxygen-free carbon dioxide, cooled, and filtered. An oil is obtained which has the following physical values: viscosity 3.4; color 4.1. With 0.03% cobalt, this oil flowed on wood or steel becomes tack-free in less than 8 hours at room temperature, the films being clear glossy, and hard after overnight drying. In view of the light color of the films produced from this oil, this material is particularly well suited for the preparation of light colored enamels.

Exmrtr: 8

Glycerol mixed ester of linseed oil acids and p-benzoylocrylic acid Percent c-benzoylacrylic acid glyceride 20.0 Linseed acids glyceride 80.0

A mixture of 192 parts of alkali-refined linseed oil, 45 parts of p-benzoylacrylic acid monohydrate (obtainable from benzene and maleic anhydride according to the general method outlined by von Pechmann, Ber. 15, 885 (1882)), and 7.1 parts of glycerol is heated according to the procedure described in Example 1 for 9 hours at 200-206 C. After being blown, cooled, and filtered, the resulting oil has the following physical and analytical valum: Np 1.5020; hydroxyl No. 29.5; acid No. 8.5; viscosity 8.8; color 10. With 0.03% cobalt, films or the oil become tack-free in 8-15 hours at room temperature. and, after exposure in Delawere for over one year, show good gloss and hardness, and excellent durability.

EXAMPLE 9 Glycerol mixed ester of linseed oil acids and a-vinylcinnamic acid Percent a-vinylcinnamic acid glyceride 20.0 Linseed acids glyceride 80.0

A mixture of 113 parts of alkali-refined linseed oil, 4.? parts of glycerol. and 26.5 parts of u-vinylcinnamic acid (prepared by condensing 212 parts or benzaldehyde with 154 parts of crotonic anhydride in the presence of 202 parts of triethylamine at -132 C. for 2.5 hours according to EXAMPLE 10 Glycerol mixed ester linseed oil acids and cinnamalacetic acid Percent Cinnamalacetic acid glyceride 24.0 Linseed acids glyceride 76.0

A mixture of 138 parts of alkali-refined linseed oil. 41 parts of cinnamalacetic acid (prepared by heating at 100 C. with stirring for 10 hours 502 parts of cinnamaldehyde, 396 parts of malonic acid, and 300 parts of pyridine, cooling and pouring into 2000 parts of 20% sulfuric acid, filtering and recrystallizin the precipitate from alcohol: see Doebner, Ber. 35, 2137 (1902)), 7.3 parts of refined glycerol, and 0.14 part of sodium hydrogen sulfate monohydrate is heated at 200-220 C. for 7 hours in an atmosphere of carbon dioxide, water being removed as in Example 1. After being blown, cooled, and filtered, the oil has the following physical and analytical values: No 1.5071; hydroxyl No. 4.4; acid No. 12.8; viscosity 4.0; color 3.25. With 0.03% cobalt, films become tack-free in less than 8 hours at room temperature and show good gloss.

EXAMPLE ll Glycerol mixed ester of linseed oil acids and a-methacrylic acid Percent m-methacrylic acid glycerlde 14.4 Linseed acids glyceride 85.6

To a mixture of 14.1 parts of water-white linseed oil acids, '70 parts of alkali-refined linseed oil, 6.3 parts of refined glycerol, and 0.7 part of sodium hydrogen sulfate, heated to 180 C., are added 14.1 parts of a-methacrylic acid and sufflcient toluene to give refluxing at about 200 C. The mixture is heated for hours at 200-210 C. under an atmosphere of carbon dioxide, the water formed being removed continuously as in Example 1. After being blown with carbon dioxide for 20 minutes to remove toluene, the product is cooled and filtered. The residue is alight-colored oil with the following physical and analytical values: Np 1.4832; hydroxyl No. 4.5; acid No. 5.8; viscosity 1.4; color 2.5. With 0.03% cobalt, this oil becomes dust-free in 2 hours at room temperature, and after overnight drying has good hardness and color.

In view of the highly reactive nature of the tip-unsaturated monofunctional monocarboxylic acids, stoichiometric mixtures with the polyhydric alcohols give essentially neutral products by the processes of this invention. However, in some cases it may be desired to use an excess of either the acid or the polyhydric alcohol. Thus, when operating by open kettle procedures using fusion technique, it is usually advisable to start with a slight excess of the unsaturated acid, since the gas blow used to facilitate removal of water often carries oil an appreciable amount of the acid. As illustrated in the examples, a slight excess of the acid may also be used as a means to speed the reaction to completion, since the excess acid is readily removed on completion of the reaction merely by blowing with an inert gas.

A indicated previously. temperatures of 180- 225 C. are generally satisfactory for obtaining essentially complete reaction in a reasonable length of time. In certain instances, however, it may be advantageous to operate either below or above this range; for example, when fusion methods are used, operation at higher temperatures, especially toward the end of the reaction. is found advantageous to eifect a more rapid completion of the reaction.

In order to obtain the best color possible, it is usually advisable to operate in glass, enamel, stainless steel, or similar equipments; however, generally satisfactory oils can be prepared in steel kettles where color is not of prime importance. Although the reactions are generally blanketed with an inert gas, this procedure is required only when excellence of color and low viscosity are desired, open kettle procedures giving otherwise satisfactory products.

For each particular combination of polyhydric alcohol, t p-unsaturated monofunctional monocarboxylic acid, and other monocarboxylic acid, there is a range of a,5unsaturated monofunctional monocarboxyiic acid-polyhydric alcohol ester content within which the products dry fastest and/or have the best film properties generally. It will usually be found that the most valuable products are obtained from that proportion of a o-unsaturated monofunctional monocarboxyllc acid which gives a product theoretically having on the order of 5-60% of the 1,5- unsaturated monofunctional monocarboxylic acid-polyhydric alcohol ester. However, the exact best range should be determined for each nip-unsaturated monofunctional monocarboxylic acid. Almost any desired degree of improvement in drying properties (up to the maximum possible for the ingredients involved), as compared to the polyhydric alcohol simple ester of the acid other than the rip-unsaturated monofunctional monocarboxylic acid, may be attained merely by varying the content of cup-unsaturated monofunctional monocarboxylic acid-polyhydrlc alcohol ester. In this respect, products containing either more or less of the latter ester than that giving optimum drying qualities may be pre pared. Where improvement in drying properties only is desired, smaller amounts of nip-unsaturated moncfunctional monocarboxylic acid-polyhydric alcohol esters are advised, whereas it may often be advantageous to use a higher concentration if some other property contributed by these esters is also desired, for example, for use in inhibiting wrinkling of coating compositions.

Preparative details are to be adjusted to the particular reaction involved, the manner of so doing being apparent to one skilled in the art. When solution techniques are used, any inert water-immiscible liquid diluent is suitable. hydrocarbons being preferable, and the amount can be varied as desired. Suitable specific solvents include toluene, xylene, para-cymene, amylbenzene, tetrachloroethane, anisol, and cyclohexanone. Aromatic hydrocarbons, chlorinated solvents, ethers, and ketones are in general suitable. A boiling point in the range -200" C. is usually desirable.

As indicated previously, the arr-unsaturated monofunctional monocarboxylic acid which can be used are those which contain no other group capable of reaction with the carboxyl group under normal esterification conditions. Examples of additional r p-unsaturated monorunctionai monocarboxylic acids which can be used are as follows: octatrien-2,4,6-oic acid, o-cyclohexylpentadien-2,4-oic acid, 6-pherwlhexadien-2,4-oic acid a, s-di-(2-furyl) acrylic acid, p-(3-iurylJ- acrylic acid, p- [2-(5-chlorofuryl) lacrylic acid, [3- i2-thienyllacrylic acid, cinnamic acid, fl-acylacrylic acid, 2-cyanohexadien-2,4-oic acid, and the like. Mixtures oi these unsaturated acids can, of course, be used where the properties contributed by each are desired. For example, the use of some a-methacrylic acid in conilmction with p-iz-furyll acrylic acid has been found to contribute appreciably toward better film color than can be obtained using the latter acid alone.

Other monotunctional monocarboiwlic acids which do not contain an ethylenio bond d, 8 to the carboxyl group can also be present in the reaction mixture. Any such acids can be used. Thus. these additional acids can be aromatic or aliphatic; open or closed chain, and, if the latter, monocyclic, polycyclic, homocyclic, or heterocyclic; saturated or unsaturated; straight or branched chain; and substituted or not by other roups or atoms such as ether, ketone, halogen, etc., which do not interfere with the esterificatiofi reaction used for the preparation of the mixed esters. In addition to those of the examples, the specific acids which can be used include th following: cottonseed oil acids, coconut oil acids, oleic acid, iuroic acid. lauric acid, paratoluic acid, quinolinic acid, phenoxyacetic acid, and the like.

Polyhydric alcohols other than glycerol can also be used in the process of this invention, such as diethylene glycol, decamethylene glycol, erythritol, sorbitol, methyltrimethylolmethane, p,p'-di(2-hydroxyethyl) benzene, and cyclohexyl- 1,2-dicarbinol, and the like.

Catalysts are desirable though not essential. Alkali metal partial salts of inorganic acids, such as sulfuric and phosphoric, will in general accelerate the reaction. As implied by the examples, sodium hydrogen sulfate is particularly efiective; thus, without it, 10 hours are required for preparing the product of Exampl 1.

Any slyceride of naturally occurring fatty acids can be used with the c p-unsaturated monofunctional monocarboxylic acids and polyhydric alcohols in the process of this invention. When rapid dry products are desired, it is usually best to employ a drying or semi-drying natural oil either in part or as the entire source of natural oil component; however naturally occurring glycerides of the non-drying type can be used with equal facility when the properties contributed by these materials are sought. Examples of naturally occurring glycerides which can be used includesuch oils as linseed, soya bean, China wood, oiticica, perilla, caster, cottonseed menhaden, and the like.

The products of this invention are especially useful as ingredients for coating compositions in the paint and varnish field. For example, they can be used directly for clear coatings, or, they can be formulated into pigmented compositions by either grinding with pigments or by using them as let-down vehicles for standard mill bases. Coating compositions prepared from the oils of this invention can also contain one or more of the following auxiliary components, as needed or desired for the intended use: natural resins, such as kauri, congo, Manilla, damar, and shellac; synthetic resins, such as hydrogenated rosin, ester gum, phenolic extended ester gums, phenolaldehyde resins, polyacrylates and methacrylates, and vinyl resins generally; cellulose derivatives, such as nitrocellulose, cellulose acetate, and cellulose esters and ethers generally; waxes; natural ying oils; other oils; fillers; corks; bitumens;

Paints formulated from red lead and the products or this invention are particularly valuable as hardrying. durable primers for steel. For this purpose, products formulated from soya bean oil and p-(ll-ruryl) acrylic acid are particularly valuable. House paints based on this vehicle also show good properties and are free of the aftertack which usually accompanies soya bean Oil paints. Aluminum paints prepared from the products of this invention or from varnishes prepared therefrom show excellent retention of leai ing characteristics on storage.

Surprisingly, it has been found possible by this invention to react simultaneously a polyhydric alcohol, a natural fatty oil, and an lip-unsaturated monofunctional monocarboxylic acid to give products of low viscosity and excellent color with the added advantage that the process is carried out in one step instead of two. It would not be expected that the two procedures could be carried out simultaneously in the presence of a single catalyst since an alkaline catalyst is generally used for the alcoholysls, and an acidic agent is required for the esterification steps, in the usual two-step preparation of synthetic glycerides. Furthermore, in view of the high reactivity of these arr-unsaturated acids and the strong tendency of their esters to undergo polymerization and Diels-Alder type condensations, it would not be expected that homogeneous, low viscosity products would result from the reaction of free acid with free polyhydric alcohol in the presence or a natural oil. It should be pointed out, in this connection, that the products of this invention, aside from having the advantage of generally lower viscosities and lighter colors, appear to be otherwise at least equal to those prepared by the former two-step process. For example, they possess essentially the same specific gravity, iodine number and refractive index, and behave the same in preparation of coating compositions, such as varnishes, enamels, and the like. Furthermore, drying properties, such as dust-free and tackfree times, hardness, print resistance, adhesion, and flexibility, appear the same.

It is apparent that many widely diflerent embodiments or this invention may be made without departing from the spirit and scope thereof; and, therefore. it is not intended to be limited except as indicated in the appended claims.

I claim:

1. A proces for the preparation of polyhydric alcohol mixed esters of fatty acids of naturally occurring oils and rip-unsaturated monofunctional monocarboxylic acids, which comprises the direct interaction 01' a naturally occurring g yceride, a polyhydric alcohol, and the afi-unsaturated monoiunctional monocarboxylic acid.

2. A process for the preparation oi polyhydric alcohol mixed esters of fatty acids of naturally occurring oils and nos-unsaturated monofun tional monocarboxyiic acids, which comprises reacting simultaneously a naturally occurring giyceride, a polyhydric alcohol, and the exp-unsaturated monofunctional monocarbozqrlic acid.

3. The process of claim 2, in which an alkali metal acid salt is used as a catalyst.

4. The process of claim 2, in which sodium hydrogen sulfate catalyst is used.

5. The process of claim 2, in which the nat- COURTLAND LE VERNE AGRE.

CERTIFICATE OF GORREC TIDE.

Patent No. 2,38 ,888-

Augus t 11;, 1914.5.

COURTLAND LE VERHE' AGHE.

It is hereby certified that error appears in the printed specification of, the above numbered patent requiring correctionae follows: Page 5, second column, line 5, for 200.225 C. read "200-225 0,"; and that the said Letters Patent should. be read with this correction therein that the same may conform to the record of the case in the Patent Office- Signed and sealed this 18th day of December, A. D. 1914.5.

(Seal) Leslie Frazer First Assistant Commissioner of iatente.

ide, a polyhydric alcohol, and the afi-unsaturated monoiunctional monocarboxylic acid.