US2891919A - Coating composition vehicles prepared from acidulated soap stocks - Google Patents

Description

United StatesPatent COATING COMPOSITION VEHICLES PREPARED FROM ACIDULATED SOAP STOCKS .NoDrawing. Application March 16, 1954 .Serial No. 416,690

11 Claims. (Cl. 260-22) This invention relates to the preparation of novel and useful 'vehicles for coating compositions, and pertains more particularly to the preparation :of :such vehicles from acidulated soap stocks obtained in the alkali refining of glyceride oils.

@Glyceride oils such as soybean :oil, corn-oil, linseed oil and the like contain variable amounts of non-glyceride impurities. To remove such impurities the oil is -subjected to a refining operation, which ordinarily involves treating the oil with a small percentage, for example, about 0.1 percent to 2 or 3 percent by weight of an .alkali'such as sodium hydroxide or sodium carbonate, this treatment serving to -neutralize the free fatty acids .in the oil to form soaps and also to eliminate break and gums in the oil. There remains in the oil, after treatment, a sort of sludge, including the soaps, which can be removed by settling or centrifugation. The material removed in this manner is ordinarily termed a fsoap stock'and is a mixture of fatty acid soaps, 'water and entrained oil. When acidulated with an acid such as sulfuric acid, a rather dark mixture of fatty acids and glycerides, including some partial esters results, this ,ma terial normally containing about 95 percent free and combined fatty acids. Although both raw and acidulated soap stocks are available in large quantities at extremely low costs, relativelylittle direct commercial use has been made of these materials.

It has now been discovered that the acidulated soap stocks can .be economically treated to produce materials whichare useful asvehicles in coating compositions,

eliicles Whichare substantially equivalent in quality to, and which cost only a fraction of the cost or conventional .vehicles such as linseed oil, fish oils, alkyd resins and oleoresinous materials.

The enhancement of the properties of the acidulated soap stocks to render them useful as vehicles for use in coating compositions in accordance withthis invention is accomplished by esterification of the acidulated soap stock with .a polyol, modification of the resulting ester with a minor proportion of an alpha, beta-ethylenically unsaturated polycarboxylic acid, and aeration of the resultant modified ester. Coating compositions containing vehicles prepared in this manner are fast drying and form films which are extremely durable and resistant to the action of weathering, light and chemicals.

The acidulated soap stocks which can be processed into useful vehicles by the following process are obtained from any glyceride oil of "vegetable or animal (marine or-land) origin. Included among such oils are the following:

Sunflower seed oil 'Poppyseed oil Satfiower seed oil Sardine oil Coconut oil Whale oil Olive oil Menhaden oil Linseed 'oil 2,891,919 Patented June 23, -1959 If a soap stock from the alkali refining of one ofthe above oils, or another oil of'vegetable or animal origin, is obtained in the raw form, that is, the product obtained directly by the alkali refining process, it can readily be acidulated simply by the addition of an acid such as hydrochloric or sulfuric acid to neutralize the product or to make it slightly acidic, in which process theacidulated material is present as an oily 'toplayer that can be recovered by decantation or other means.

The properties of typical acidulated soap stocks are listed in the following table.

TABLE I Soybean Acidulated Corn 011 Soap Stocks Aeidu- Linseed Soap Stock Type lsated Acid Oil oap Type A Type B Type 0 Stock Acid Value 98. 2 144. 9 93. 5 185. 6 12,4. 0 Iodine Value 129. 6 132. 2 132. 9 119. 3 ,161. 1 Gardner Color 18+ 18+ 18+ 18+ 18+ Percent Moisture 2. 2 1 3 1.0 1. 6 0.8 Percent Unsaponifiable matter 7. 11 4. 06 9. 42 6. 46 5. 67 Percent tocopherol 0. 37 0. 47 0. 42 0.62 0.40

Three different types of acidulated soybean soap stocks are shown in the above table to demonstrate the fact that the properties may differ from sample to sample due to slight variation in alkali refining procedures or in the oil processed.

As mentioned hereinabove, the acidulated soap stocks possess .some free or available hydroxyl groups. The amount of available hydroxyl can be ascertained if desired either by trial esterification and determination of the drop in the acid value, or by a direct determination of thehydroxyl content of the acidulated soap stock. The amount of polyol which must be added in the esterification process can be adjusted accordingly.

The esterification of the acidulated soap stock can be carried out utilizing any of the various polyols. Examples of such polyols include ethylene glycol, glycerol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, pinacol, pentaerythritol, trimethylolethane, polyallyl alcohol, sorbitol, alpha-methyl glucoside, epoxide resins containing hydroxyl groups, polypentaerythritols, and the like. Obviously, the quantity of polyol employed .depends in large measure on the amount of available hydroxyl in the acidulated soap stock as determined "by one of the methods described above. In general it is desired that the polyol be employed in an amount. such that substantially complete esterification of the acidulated soap stock is obtained, that is, until an acid number of about 15 is reached. Mixtures of two or more polyols may sometimes be utilized advantageously, particularly a mixture of glycerol and pentaerythritol.

The esterification process is best carried .out by heating a mixture of the acidulated soap stock and the polyol in an inert solvent or diluent such as toluene or xylene at a temperature in the range of about C. to 300 C. or higher for a period of from about 1 hour to .o'hours or more. A catalyst is not necessary to efifect theesterification, particularly if a relatively large amount of acid is present in the soap stock, although the time of reaction may be decreased somewhat by utilizing .a conventional esterification catalyst such as litharge or toluenesulfonic acid, or the like. It is desirable to utilize a silicone antifoaming agent in a very small amount during the esteri fica'tionto prevent foaming which is likely to occur 3 during the esterification of the crude acidulated soap stocks, and additionally to employ an inert gas to prevent oxidation of the double bonds of the hydrocarbon groups in the fatty acids present.

The preferred alpha, beta-ethylenically unsaturated polycarboxylic acid for use in modifying the acidulated soap stock esters prepared according to the procedures described in the foregoing paragraph is maleic acid. However, other acids, including fumaric acid, crotonic acid, acrylic acid, itaconic acid and the like may be utilized. Alpha, beta-ethylenically unsaturated acids containing halogen or other substituent groups may also be employed, as may the anhydrides of any of the foregoing acids; in fact, the anhydrides are preferably utilized in the esterification reaction and it is intended that the terms acid include the corresponding anhydride. In most instances about 2.0 percent to 8.0 percent of the alpha, beta-ethylenically unsaturated acid, based on the weight of the acidulated soap stock, is used. However, smaller or larger amounts may also be utilized, with the larger amounts giving somewhat improved drying properties.

The alpha, beta-ethylenically unsaturated acid is preferably added to the esterification reaction mixture after esterification of the acidulated soap stock with the polyol is substantially complete. If the unsaturated acid is added while substantial polyol is present in the reaction mixture, the acid and polyol may react to form a relatively insoluble precipitate; for example, when maleic acid and glycerol are present, glycerol maleate may be formed. It is obvious, therefore, that where the presence of such a precipitate is objectionable, the alpha, betaunsaturated acid should not be added until most of the polyol has reacted with the acidulated soap stock.

The modified esters thus prepared can be used per so as vehicles in coating compositions. However, they do not dry as well as is desired for certain applications, probably due to the presence in the acidulated soap stocks of certain antioxidants, particularly tocopherol. Accordingly, it is another feature of this invention that the drying properties of the modified esters can be greatly improved by blowing air through the ester in a controlled manner to destroy the inhibitor, but not to oxidize the oil to any significant extent.

In the aeration process, the addition of small amounts of catalysts of oxidation and particularly catalysts such as are conventionally employed as driers in paints and varnishes is important. These catalysts include the various salts of heavy metals such as cobalt, nickel, chromium, manganese, lead, and the like, that have at least slight solubility in the modified ester. The salts may be, for example, the oleates, linoleates, naphthenates, resinates or the like of the foregoing metals. Soluble forms of these materials are now available. The amount of the drier is small and usually will be within a range of about .0001 to .001 percent by weight, with the preferred range being about .0002 to .0006 percent by weight. These percentages are calculated as active metal based upon the total amount of modified ester which is treated.

The temperature of treating the modified ester is preferably within a range of about 230 F. to 280 F., although higher or lower temperatures may also be utilized successfully. The aeration may be carried out in any convenient reactor.

Air constitutes the usual oxidizing agent, but it is to be understood that oxygen gas can also be utilized by appropriate adjustment of the amount and the rate of addition. The air (or oxygen) is more effective if it is thoroughly distributed in the modified ester which is undergoing treatment. Various types of agitation may be employed. For example, the air may be whipped or stirred relatively uniformly in tiny bubbles in the ester by means of conventional agitators or turboagitators. It is also possible to break up the air or oxygen as it is supplied to the ester by bubbling it into the ester through a distributor head provided with minute openings.

In most instances the total amount of air (assuming air is employed as the oxidizing agent) will not exceed 2.5 cubic feet of air per gallon of oil, with about 0.2 to 1.0 cubic foot of air per gallon of oil being preferably utilized. Considerable variation in the rate of addition of air (or oxygen) can be tolerated but usually the rate will be within the range of 0.005 to 0.02 of air or 0.001 to 0.004 of oxygen expressed in terms of cubic foot per minute per gallon of oil treated. It is to be understood that if oxygen is employed, the necessary reduction in volume to compensate for the increased concentration of the active agent should be made.

The time of aeration can be varied substantially but in most instances will be within the range of about 2 to 6 hours, and preferably 2 to 4 hours. Excessively protracted aeration will result in increases in the viscosity of the oil, in peroxide value and of acid value which may in some instances be objectionable.

The completion of the aeration of the oil can easily be determined by conventional tests for inhibitors, for example by the well known Emmerie-Engel test. The overall inhibitor content of the ester is reduced as much as 98 percent by the aeration process.

The following examples are intended to illustrate more fully the preparation of vehicles from acidulated soap stocks in accordance with the practice of this invention. The examples are not, however, intended to limit the scope of the invention for there are, of course, numerous possible variations and modifications.

Example I The following materials were charged into a glass lined reactor:

Soybean acidulated soap stock,

Silicone anti-foaming agent 40 cc. (1% solution).

The resulting mixture was heated at a temperature within the range of about 200 C. to 235 C. for 4% hours. One and two-tenths pounds of maleic anhydride were then added over a 10 minute period and heating was continued at about 235 C. for an additional 5 hours. The resultant product had an acid value of 9.5, a viscosity of L (Gardner-Holdt), a Gardner color of 18+ and a solids content of 95.5 percent.

The modified ester thus prepared was then aerated for about 2 hours at 230 F. in the presence of about 0.001 percent cobalt (as the nahphthenate), utilizing 0.075 cubic foot of air per minute. The final product contained only 0.04 percent of tocopherol. Drying tests utilizing 6.9 cc. of a lead-cobalt drier (0.3 percent lead and 0.03 percent cobalt) per 100 grams of resin solids were made on the original and aerated samples. The original ester set to touch in 320 minutes and the aerated ester in only minutes.

The aerated ester prepared according to the above method was formulated into a conventional house paint and showed no appreciable checking, flaking, peeling or chalking after prolonged exposure under various climatic conditions. The paint was found to be the sub-= stantial equivalent in durability and other properties to paints utilizing a linseed oil vehicle.

Examples 11 to IX A series of vehicles was prepared from various acidulated soap stocks as follows. The soap stock was first heated with pentaerythritol for about 1 to 4 hoursin the-same manner and substantially'the same temperatures as set forth in Example I. Maleic-anhydride was-then added and the heating continuedat about 235 C. until 6 Vehicle type: Average durability Pentaerythritol-ester of linseed oil .210 Cyclopentadiene treated'soybean oil Milli/iii ii -4 ester was then aerated by blowing with air for from 2 5 Blown safflower oil 7.0 "to 6 hours at about 230 F., the air being supplied at the Blown linseed 011 9.0 rateof about 0.075 cubic foot per minute. The per- Bodied, crude and rosln extended mixture of them data are recorded in the table below: llnseed oll 5.0

Charge Physical Properties Exam 1e Soap Stock "1 pa Miscellaneous p y Soap Penta- Maleic Stock erythritol Anhydride Viscosity Gardner Acid Percent (Grams) (Grams) (Grams) Color Value oilds .II .ac i dulatgd soybean soap'stocks- 2,500.0 156.0 50.0 (2%) E 18+ 6.0

F1 i III Ac idulatfii-soybean soap stocks- 2,500.0 215.0 75.0 (3%) 16 d(grains Glycerol N 18+ 9.0 198.0

. ype a e IV Ac ivdulatgl soybean-soapstocks- 2,500.0 193.0 95.0 (4%) P 18+ 7.2 95. 6

e V. -Iig 1,500.00 116.0 504.01%) 2.85 griams Litharge '1 18+ 7.2

a e 229.0 141.0 (6% V 18+ 9.0 95.1 127.8 96.0 (8% Zr; 18+ 95:2 227.9 125.0 (5) Anili'oiming agent T 18+ 9.9 96.0

a e IX Acidulated linseed oil 1,200.0 80.0 1.5.?i dgrsms Lltharge F+ 18+ 9.9 94.8

The vehicles prepared in the above examples were formulated into paint compositions for exterior use as follows:

Pigments (litharge, zinc oxide, iron oxide,

Venetian red (iron oxide 33%, calcium sulfate 67%, asbestine) 42.1

Vehicle (prepared acording to method of Example I) 31.9 Driers 7.2 Solvents 18.8

The resulting compositions were applied to test panels and exposed to weathering in several ditierent locations in the United States for 24 months. The panels were then compared with panels coated with paints prepared using other vehicle types including the conventional linseed oil (raw, blown or bodied), fish oils and soybean oil. The panels were rated on the basis of appearance, checking, flaking, peeling and chalking, a value of being considered as maximum durability on all the above factors. The comparison is set forth below:

Vehicle type: Average durability Modified-aerated ester prepared according to method of Example III 8.3 Modified-aerated ester prepared according to method of Example V 9.0 Maleic acid-pentaerythritol modified whole fish oil 3.5 Maleic-pentaerythritol modified 75% fish oil,

25% soybean oil 3.0

The above data demonstrates conclusively that the very economically prepared vehicles of the present invention are the equivalent of the more expensive conventional vehicles. In addition the formulations based upon the vehicles of this invention give initially equally good appearance, brushability and gloss and a more positive drying than paints containing a linseed oil vehicle. Accordingly, the vehicles prepared from acidulated soap stocks can be substituted in whole or part for more expensive vehicles in both interior and exterior coating compositions, particularly in colored paints. Since the acidulated soap stock vehicles tend to be relatively dark, they cannot ordinarily be utilized as the sole vehicle in a white paint, but can be used in amounts up to about 50 percent in such compositions. The color of the vehicles can be somewhat improved by bleaching with a material such as sodium chlorite, NaClO bleaching earths or activated carbons, although for colored coating compositions such treatment isnot necessary.

Example X Seven hundred eighty grams of the modified ester prepared according to the method of Example I was formulated into a varnish by heating the modified ester with 500 grams of pentaerythritol-maleic acid-rosin ester gum (prepared from 2500 grams rosin, 538 grams pentaerythritol and 312.5 grams of maleic anhydride). The cook ing log is as follows:

Tempera- Viscosity at Time (Minutes) ture C.) 50% Total Solids The product thus obtained was thinned to 48.2 percent total solids (Gardner viscosity G) in a high flash aliphatic naphtha, giving a varnish having a Gardner color of 16.5. The drying rate and other properties of the varnish was equivalent to that of an analogous varnish utilizing linseed oil as the oil component.

The modified esters of the above examples may be readily bodied if desired. For example, when the ester prepared according to the method of Example I is heated and aerated for about 4 hours at 300 C., the resultant product has a Gardner-Holdt viscosity of Z, and a Gardner color of 16.0 at 25% total solids.

The acidulated soap stocks may also be utilized to prepare alkyd resins, the drying properties of which can be greatly improved by aeration. The aeration process may be carried out upon the acidulated soap stocks, the esterified acid oil, the esterified oil modified with the unsaturated acid, or upon the alkyd resin.

From the foregoing specific examples, it is readily apparent that the vehicles prepared according to the process of the present invention constitute a novel and useful class of materials. It is also apparent, therefore, that various embodiments of the invention, in addition to those specifically disclosed, may be provided without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

'1. A method of preparing a product useful as a vehicle in coating compositions, which comprises substantially completely esterifying an acidulated soap stock with a polyhydric alcohol containing from 2 to 4 hydroxyl groups at a temperature of about 150 C. to 300 C., reacting the resultant ester with about 2 percent to 8 percent by weight of the acidulated soap stock of an alpha, beta-ethylenically unsaturated polycarboxylic acid, and then blowing the reaction mixture with a member of the class consisting of air and oxygen in the presence of a metallic drier in an amount such that there is present from about 0.0001 to 0.001 percent by weight of active metal, based upon the weight of the acid modified ester, for a time sufiicient to remove substantially all of the antioxidants present in said reaction mixture.

2. The method of claim 1 wherein said member of the class consisting of air and oxygen is utilized in an amount such that from 0.001 to 0.004 cubic foot per minute of oxygen is utilized per gallon of ester for a period of about 2 to 6 hours.

3. The method of claim 2 wherein the alpha, betaethylenically unsaturated polycarboxylic acid is maleic acid.

4. A vehicle for coating compositions prepared according to the method of claim 2.

5. The method of claim 1 wherein the acidulated soap stock is a soybean oil soap stock and the polyhydroxy alcohol is pentaerythritol.

6. A method of preparing a product useful as a vehicle in coating compositions which comprises substantially completely esterifying an acidulated soybean oil soap stock with pentaerythritol at a temperature of about C. to 300 C., reacting the resulting ester with from about 2 percent to 8 percent by weight of maleic anhydride at a temperature of about 200 C. to 250 C., and then blowing the reaction mixture with air for about 2 to 6 hours at about 230 F. to 250 F. and at a rate such that the reaction mixture is treated with oxygen in an amount of from about 0.001 to 0.004 cubic foot per minute per gallon of ester, in the presence of a metallic drier in an amount such that there is present about 0.0001 to 0.001 percent by weight of active metal based upon the amount of ester treated with air.

7. The method of claim 6 wherein the acidulated soybean oil soap stock is replaced by an acidulated corn oil soap stock.

8. The method of claim 6 wherein the acidulated soybean oil soap stock is replaced by an acidulated linseed oil soap stock.

9. A vehicle for coating compositions prepared according to the method of claim 1.

10. A pigmented paint composition, the vehicle thereof comprising the product of claim 9.

11. A varnish composition, the vehicle thereof comprising the product of claim 9.

References Cited in the file of this patent UNITED STATES PATENTS 1,872,568 Ellis Aug. 16, 1932 2,063,855 Rosenblum Dec. 8, 1936 2,078,239 Ellis Apr. 27, 1937

Claims (1)

1. A METHOD OF PREPARING A PRODUCT USEFUL AS A VEHICLE IN COATING COMPOSITIONS, WHICH COMPRISES SUBSTANTIALLY COMPLETELY ESTERIFYING AN ACIDULATED SOAP STOCK WITH A POLYHYDRIC ALCOHOL CONTAINING FROM 2 TO 4 HYDROXYL GROUPS AT A TEMPERATURE OF ABOUT 150* C. TO 300* C. REACTING THE RESULTANT ESTER WITH ABOUT 2 PERCENT TO 8 PERCENT BY WEIGHT OF THE ACIDULATED SOAP STOCK OF AN ALPHA, BETA-ETHYLENICALLY UNSATURATED POLYCARBOXYLIC ACID, AND THEN BLOWING THE REACTION MIXTURE WITH A MEMBER OF THE CLASS CONSISTING OF AIR AND OXYGEN IN THE PRESENCE OF A METALLIC DRIER IN AN AMOUNT SUCH THAT THERE IS PRESENT FROM ABOUT 0.0001 TO 0.001 PERCENT BY THE WEIGHT OF ACTIVE METAL, BASED UPON THE WEIGHT OF THE ACID MODIFIED ESTER, FOR A TIME SUFFICIENT TO REMOVE SUBSTANTIALLY ALL OF THE ANTIOXIDANTS PRESENT IN SAID REACTION MIXTURE.