US2120089A - Process of preparing oil compositions - Google Patents

Description

Patented June 7, 1938 UNITED STATES PATET OFFICE PROCESS OF PREPARING OIL GOIWPOSI- TIONS No Drawing. Continuation of application January 20, 1933, Serial No. 652,688. This application January 31, 1936, Serial No. 61,744

8 Claims.

This invention relates to the production of oil compositions, and more particularly, to a process of producing homogeneous dispersions of solid-gelled non-drying vegetable oils in a liquid medium, and is a continuation of our copending application Serial No. 652,688.

Incopending application Serial No.- 545,840, filed June 20, 1931, a'method of preparing homogeneous dispersions of a solid-gelled non-drying vegetable oil in a liquid medium is disclosed. Prior to the process outlined.in this earlier application, several investigators had made numerous unsuccessful attempts to incorporate solidgelled castor oil in nitrocellulose coating compositions.

Ordinary mixing in available mixi-ng machinery, even at high speeds failed to provide homogeneous dispersions in liquid mediums such as the solvents and diluents utilized in the lacquer industries. The solid-gelled oils are substantially insoluble in these solvents and, therefore, even when subjected to extended mixing failed to dissolve or to homogeneously disperse so as to be capable of use. Invariably the results were the same, regardless of modifications introduced with respect to mixing cycles, ratio of solvent to oil, or type of standard lacquer solvent or diluent employed. Further efforts to utilize a ball mill, a standard equipment of the lacquer industries, which makes use of the grinding action of steel or porcelain balls or pebbles, were likewise unsuccessful. Here again the solid-gelled oil showed no tendency to disperse or dissolve in.

the solvent or diluent.

Investigational work on these solid-gelled oils led to no commercial use in coating compositions, ,and the like, until Arnold and Callahan, as outlined in their patent application Serial No. 545,840 mentioned above, devised a process for incorporating solid-gelled oils homogeneously in nitrocellulose solutions, and other liquid inediums, by means of colloid rolls. This process permitted the manufacture of nitrocellulose compositions containing solid-gelled oils, thereby bringing to light the several advantages inherent to such combinations.

This invention has as an object to provide a new and economical process whereby solid-gelled non-drying vegetable oil may be homogeneously dispersed in a liquid medium. A further object of the invention is to provide a process for dispersing solid-gelled non-drying vegetable oil in cellulose derivative coating compositions. A still further object is to provide a process for carrying out the above dispersion, which is characterized by simplicity and high degree of efliciency and economy of operation. A still further object is to provide a process of carrying out the above dispersion with a small amount of readily available equipment. Other objects will appear hereinafter.

These objects are accomplished according to the present invention by kneading a solid-gelled non-drying vegetable oil in a Werner-Pfieiderer, or similar type of mixer, which gives a kneading action until the oil changes from the characteristic translucent mass to an opaque mass, and then either adding a cellulose derivative to the oil in the mixer and continuing the kneading action until the whole mass becomes homogeneous and dispersing the mass in a solvent mixtur for the cellulose derivative by adding the solvent mixture gradually thereto, or dispersing the kneaded oil, without incorporating a cellulose derivative, in any desired liquid medium.

The term solid-gelled non-drying vegetable oil as used herein, may be defined as any vegetable oil that is not classified as a drying oil, which has been polymerized and/or oxidized by heating, and/or blowing, to such a high degree that it becomes gelled and semi-plastic and will not flow. An oil in such condition is not to be confused with the well-known blown or boiled oils which have a high viscosity but are by no means gelled, nor with drying oils, such as linseed or china-wood oil, which have been polymerized to such a high degree that theybecome crumbly. The solid-gelled non-drying oils are substantially insoluble in the usual solvents and diluents used in various nitrocelluose coating compositions, and in that respect are sharply distinguished from the common solid plasticizers such as triphenyl phosphate, phenyl salicylate, and the like, used in cellulose derivative compositions, and which are soluble in the usual solvents and diluents used in such compositions.

The following examples are given to illustrate the process of the present invention. A solidgelled castor oil was used in these examples, which was amber in color, transparent, and substantially insoluble in the usual lacquer solvents and diluents. It had a gel-like structure, having a time of six minutes for a mobilometer rod weighted with 200 grams to penetrate one inch into the oil. The size of the initial charge is dependent upon the size of the kneading machine employed, because it is necessary that the initial charge of oil be great enough so that the blades of the mixing machine meet with sufiicient resistance to set up a shearing and tearing A Werner-Pfieiderer kneading machine (2-gallon capacity), as marketed by the Baker-Perkins Company, was used and the final composition was as follows:

Grams Solid-gelled castor oil 2200 Pyroxylin (viscosity 200 sec.) 550 Denatured alcohol 2'75 Ethyl acetate 2500 Toluol 2500 The initial charge of 2200 grams of solid-gelled castor oil represents about the minimum charge which will afi'ord proper kneading conditions for this size mixer. The viscosity characteristic of the nitrocellulose was determined according to A. S. T. M. Tentative Specifications and Tests for Soluble Nitrocellulose, designation D-301-30T.

The solid-gelled oil was first added and the machine operated for a period of approximately one hour, or until the desired breakdown of the oil has occurred. .Obviously this stage may be reached in less than one hour if the kneading machine is operated at a rapid rate, and more than one hour will be required if the machine is operated at a low rate. This holds true not only for this example, but for all the examples given. During this period the physical structure of the oil appears to be broken down and the oil changes from an amber colored, transparent gel to a yellow opaque mass, indicating the end point of the required kneading. This treatment causes no significant change in the actual consistency of the oil, although a very slight drop in consistency may be observed it critically examined and the oil appears to be slightly more tacky. However, with the exception of the color and opacity changes just noted, and the physical change which is not visually apparent, but which nevertheless does take place since the oil may now be readily dispersedlin an organic liquid medium, the oil in other respects is in nature quite similar to the oil prior to the kneading treatment which is described in detail above. If the ofi is not pulled' or kneaded for" a sufiicient length of time for it to assume this new condition, the final dispersion will not be homogeneous, but will be characterized by the presence of an appreciable amount of undispersed lumps of oil which have retained their original structure and appearance. Therefore, this kneading should be continued until all or the oil has been broken down, as indicated, and no amber colored transparent lumps are visible in the mass.

The nitrocellulose, wet with alcohol according to standard practice, was-then added gradually with continued kneading. Mixing was continued for a period oi. one to two hours to insure uniform distribution oi. the nitrocellulose throughout the The nitrocellulose was not dissolved to any appreciable extent during this stage,

mass of oil.

but its identity was practically lost, since it became coated and uniformly distributed throughout the oil mass.

The solvent mixture of equal parts of toluol and ethyl acetate was then added very gradually at first with continued mixing. The adding of the entire charge of solvent mixture at one time was avoided, since definitely better results are obtained with gradual additions. With the addition of this solvent mixture, the character of the composition changed irom the yellow opaque mass to a clear amber colored dispersion, which is quite fluid and can readily be removed from the mixer.

Thecomposition in these proportions is rather too heavy for ordinary use and it is therefore advisable to further disperse this mixture in additional solvents. This can readily be carried out in an ordinary mixer commonly used in the lacquer industry. For example, a composition of 20% solids, which represents a coating composition readily usable in the art, may be secured as follows:

Percent Above mixture 58.4 Ethyl acetate 21.8 Toluol 14-.8 Isobutyl acetate 5.0

In making up this final composition no special precautions need be observed, since the mixture readily disperses in the added solvents with ordinary mixing technique. If the Werner-Pfieiderer mixer is of sufficient capacity, the additional solvents may be added there, thus avoiding the necessity of additional equipment. It is obvious that by adding more or less solvents, compositions of any desired solids may be secured, depending upon the purpose for which they are intended.

Example 2 A second and more flexible method provides for the dispersion of the solid-gelled oil in a liquid medium comprising a single solvent, o group of solvents, and diluents. In this form, then, it may readily be subsequently incorporated with cellulose derivative compositions in any proportions desired.

For convenience then, we may disperse the solid-gelled castor oil in toluol or alcohol.

As described above, the solid-gelled oil is added first to the Wemer-Pfieiderer mixer in sufilcient quantity to permit pulling or kneading action to break down the physical structure of the oil. This first step is identical to that described above.

The addition of nitrocellulose, as indicated for the second stage in Example 1, is omitted here.

Instead, when the oil has reached the physical appearance as described above, that is, become uniformly yellow opaque, the solvent, or mixture of solvents, is added gradually with continued kneading until a transparent, amber colored. homogeneous solution is secured.

A representative charge, using the same equipment as in Example 1, is as follows:

. Grams Solid-gelled castor oil 2200 Toluol (or alcohol) 2200 The availability of the solid-gelled castor oil base noted above permits a more flexible utilization, and the preliminary treatment which places it in a homogeneous solution obviates any further difficulty in connection with standard practices. For this reason, the latter example is of perhaps greater merit from the commercial angle in its simplicity and flexibility.

A ratio of equal parts of solid-gelled oil and thinner is indicated, but it will be understood that this may be varied over wide limits depending upon the use for which the solution may be put, a higher solids and higher viscosity being preferable in some cases and a lower solids with corresponding lower viscosity in others.

The above examples merely illustrate specific preferred embodiments of the invention, which is broadly applicable to solid-gelled non-drying vegetable oils, and not merely the particular castor oil above disclosed. Solid-gelled castor oil is the preferred non-drying vegetable oil; but the process is broadly applicable to non-drying vegetable oils such as solid-gelled rape, cocoanut, and cottonseed oils.

It will also be understood that various resins (natural or synthetic), gums, pigments or dyes, may be incorporated in the basic dispersion of the solid-gelled oil in a liquid medium, and may with out the'incorporation of nitrocellulose serve as a basis for a coating composition. Where it is desired to include a cellulose derivative, nitrocellulose is preferable, but other derivatives such as ethyl cellulose, and other ethers, cellulose laurate, cellulose nitroacetate, and other esters may be used in place of cellulose nitrate. The viscosity characteristic of the nitrocellulose may be varied over a wide range, from a very low viscosity such as indicated by /2 second nitrocellulose to a high viscosity, almost a gel, limited only by its workability for the purpose intended.

It will also be understood that the solvents and diluents given in the examples may be replaced by other solvents and diluents, such as are well known in the art, and that the proportions of ingredients can be varied widely, for example, the solvent and diluent content may be reduced to such an extent that a composition of very high consistency, almost without flow, may be obtained, or a. composition of very low viscosity may be secured by adding greater amounts of solvents and diluents. The particular proportion of ingredients will be largely influenced by the use for which the composition is desired.

In carrying out the process of the present invention, it is necessary to give the solid-gelled oil a kneading to a point where the transparent mass becomes opaque, and it is also preferable to add the solvents slowly to avoid breaking up of the oil mass into separate portions which will float around the blades of the machine and delay, or entirely prevent, the uniform dispersion in the liquid dispersing medium. Although a Werner- Pfieiderer mixer has been found very advantageous for the kneading step, other mixers which will give a kneading action to the mass may be used, such as a Banbury mixer.

Applicants do not claim to know exactly what change occurs in the structure of the oil during the initial kneading treatment, but the fact that some change occurs is apparent from the change in the physical appearance of the oil, and the fur-- ther fact that the oil cannot be uniformly dispersed unless kneaded to this point. It is not believed that a true solution of the oil in the various lacquer solvents and diluents occurs. but rather that the solld-gelled oil is uniformly dispersed throughout the liquid medium in apparently the form of a colloidal type solution. This belief is borne out by the results of the application of this type of composition to the more porous and open types of surfaces, such as the deeper cuts of leather, the resulting finish showing very little tendency to strike into the surface, the film forming ingredients having a tendency to remain on top, whereas in a true solution, the film forming ingredients would be carried into the leather, as in the case of the leather coating compositions heretofore known.

The kneading process disclosed above provides a method for securing a uniform and homogeneous dispersion of the solid-gelled oil in liquid solvents and diluents with which it is otherwise incompatible, and thereby permits a more general utilization of a product which has numerous industrial uses in the finishing art.

We are aware that it has been proposed in Patents Nos. 1,794,325, 1,796,219 and 1,889,702 to treat certain oils in the presence of a catalyst with heat and air until they are oxidized to a crumbly mass, which is comparatively easily dissolved in ordinary cellulose nitrate solvents. We make no claim to the invention disclosed in those patents, since our process is concerned with the use of an oil which has not been oxidized and polymerized to a crumbly state and which likewise does not reach such condition by applying the very moderate kneading treatment hereinbefore described.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

We claim:

1. Process comprising kneading a semi-plastic solid-gelled vegetable oil until it has changed from-a translucent semi-plastic mass to a yellow opaque semi-plastic mass without substantial change in consistency, and then dispersing the same in a liquid medium.

2. Process comprising kneading a semi-plastic solid-gelled non-drying vegetable oil for about one hour, stopping the kneading treatment when the oil has changed from a translucent mass to a yellow opaque mass, and before substantial change in consistency has occurred, feeding a cellulose derivative into the mass at this stage while continuing the kneading, and kneading the mass further until the cellulose derivative is uniformly dispersed in the solid-gelled oil, and then physically dispersing the mixture in a solvent mixture for the cellulose derivative.

3. Process comprising kneading semi-plastic solid-gelled castor oil for about one hour, stopping the kneading treatment when the oil has changed from a translucent mass to a yellow opaque semi-plastic mass, and before it has reached the crumbly stage, feeding a cellulose derivative into the mass at this stage while continuing the kneading, and kneading the mass further until the cellulose derivative is uniformly dispersed in the solid-gelled oil, and then physically dispersing the mixture in a solvent mixture for the cellulose derivative.

4. Process comprising kneading a semi-plastic solid-gelled non-drying vegetable oil in a Werner- Pfleiderer type mixer for about one hour, stopping the kneading treatment when the oil has changed from a translucent mass to a yellow opaque semiplastic mass, and before substantial change in consistency has occurred, feeding a cellulose de-- rivative into the mixer at this stage while continuing the kneading, kneading the mass further until the cellulose derivative is uniformly physically dispersed in the solid-gelled oil, and then dispersing the mixture in a solvent mixture forthe cellulose derivative.

5. Process comprising kneading semi-plastic solid-gelled castor oil in a Werner-Pfleiderer type mixer for about one hour, stopping the kneading treatment when the oil has changed from a translucent mass to a yellow opaque semi-plastic mass, and before it has reached the crumbly stage, feeding a cellulose derivative into the mixer at this stage while continuing the kneading, kneading the mass further until the cellulose derivative is uniformly dispersed in the solid-gelled oil, andthen physically dispersingthe mixture in a solvent mixture for the cellulose derivative.

6. Process of preparing a homogeneous dispersion of an oil in a liquid medium which comprises lumps have disappeared and then dispersing the.

same in a liquid medium.

7. Process of preparing a homogeneous dispersion of an oil in a liquid medium which comprises kneading a non-drying vegetable oil which has been rendered solid-gelled by treating it until semi-plastic and stopping the treatment before the oil reaches the crumbly stage, for approximately one hour until it has changed from a translucent mass to ayellow, opaque semi-plastic mass without substantial change in consistency and no transparent lumps are visible, and then dispersing the same in a liquid medium.

8. Process of claim 7 in which the non-drying oil is castor oil.

' PAUL B. COCHRAN. ROBERT T. HUCKS.