US 2304308 A
Description (OCR text may contain errors)
.aienieoi. Dec. i942 amazes nrsrnnsmtn coimosnnon Loren C. Hui-d1, Glenside, lPa., assignor to Riilim & Haas Company, Philadelphia, Pa.
No Drawing. 7 Application .llnne 24 Serial No. 280,910
This invention relates to the dispersion of finely divided solids and particularly to the dispersion of one finely divided solid when mixed with another such solid. The invention deals with a method for improving the degree of dispersion or the dispersibility of a powder, particularly a dry powder, by treating it with a lyophilic protein colloid and a tanning'agent.
It has frequently been observed that it is'very dimcult to mix two or more dry powders and obtain an entirely even, uniform distribution, free from agglomerates of at least one of the con,- stituents of the mixture. For example, in the preparation of parasiticidal dusts, containing a toxic ingredient, such as calcium arsenate, or cuprous oxide, or both, in a diluent such as clay or talc, the toxic material tends to ball up and segregate instead of becoming evenly and uniformly distributed throughout the mass. In the manufacture of tinted water paints of the dry calcimine type, it is not easy to incorporate dry tinting materialsuniformly throughout a mass oi. powder so that no streaks of color will appear upon examination of the dry mixture. In general the mixing of dry materials has frequently been impractical, because no simple, adequate method -without resorting to involved and prolonged grinding and mixing operations. Further, it is an object'to improve the'dispersibilityof one powder in another in such a manner that the time required to secure a given uniformity under a given set of conditions is greatly reduced. It is" also an objectto improve the dry dispersibility of one solid in another to such an extent that homogeneity of the final mixture may be at I tained with simple and inexpensive equipment. Ancillary objects are to provide parasiticides in dry'form which possess increased effectiveness,
v to improve the quality of dry, mixed pigments and colors, to increase the tinting and toning power of a pigment in white, neutral colored or colored pi ments. c r e or dry ue ta-and to treated is dissolved in asuitable liquid, such as allow production of more uniform ceramic frits, cements, plasters, etc.
These objects are accomplished by treating a finely divided solidwith a lyophilic protein colloid and then with a. tanning agent. The processing of the finely divided solid is mostv conveniently performed while the solid is suspended in a liquid. The finely divided material may also be made, into a paste with a solution of a lo lyophilic protein and treated with a solution of Q a. tanning agent. Excess liquid is then taken oil. The solid material may be driedand ground at this point, if desired.
Asa result of this process, solid material is obtained which may readily be mixed with a dry powder by stirring, agitating, or grinding.
The solids which are treated with advantage include a wide variety of insecticides, fungicides,
\ pigments, lakes, toners, dyes, opacifiers, inorganic oxides, minerals, insoluble salts, soluble salts, catalyst, and the like.
In the preferred method of treatment the material to be treated is taken up with a suitable liquid to form a sludge or suspension. A solution or dispersion .of a lyophilic protein colloid is thoroughly stirred into the suspension. A solution of a tanning agent, that is, a substance which is known to react with or precipitate proteins, is added slowly with emcient stirring.
:30 After the material has been treated, it is separated from excess liquid by any suitable method such as decantatiomfiltration, or centrifuging, and dried under conditions suitable for the particular material at hand. It may then be readily 35 incorporated with other powdered products, such as clay, talc, chalk, lime, gypsum, cement, pigments, etc. depending on the application intended.
Alternatively, a powder may be treated with a 40 lophilic protein while in a slurry or suspension, separated, and dried. The protein-treated powder is then subjected to the 'action of a tanning agent, which may be in dry form or in solution -in water or other solvent, such as alcohol or 40 ketone. In this way it is possible to carry out the process in two stages and use liquids other than water. It is also possible to 'obtain improved dispersibility by dry grinding together 'a solid and a protein, followed by grinding with a 50 tanning agent.
This permits the processing of insoluble or soluble materials, but the general method is also adaptable to the treatment of soluble material in a wet way. In this case the material to be water, the protein is added, preferably in a dissolved form, and thoroughly stirred through the solution, the solid and protein are then precipitated by the addition of a liquid which is miscible with the solution but which has less solubility for the dissolved material than the original solution, and the precipitated material is then treated with a tanning agent dissolved in a liquid which is substantially a non-solvent for the precipitated material. The solid is then dried. It may be ground, if desired.
The treatment with protein and with tanning agent may be performed at room temperature or at elevated temperatures. The use of heated suspensions or solutions often shortens the time of treatment and provides improved conditions for handling the various materials involved.
The lyophilic protein colloids which may be used for the treatment of powders includ albumen, geiatin, glue, casein, and other water-dispersible, nitrogenous, colloidal proteinic materials. Animal glues of various origins are particularly economical and effective. The amount of protein required for proper dispersion of a solid varies from about 0.05% upward, based on the weight of the material to be dispersed. Usually the addition of 0.2% to??? of protein is preferred. Larger amounts of protein may be used inthose applications where the bonding action of the tanned protein is not objectionable.
The tanning agents, which are reacted with the lyophilic proteins to improve the dispersion of finely divided solids in solids, include the salts of heavy metals such as chromiu-m, aluminum, iron, tungsten, zirconium, thorium, and cerium. These metals are known to give fixation or hide substances. Tannic acids from various natural sources, such as gall nuts, quebracho. and the like, are likewise effective as are the syntans.
The latter include a wide variety of synthetic substances, such as naphthalene sulfonic acid condensed with formaldehyde, phenol sulfonic acids, such as dihydroxydiphenyl methane disulfonate, aryl sulfonic acids condensed with formaldehyde and phenols, urea, or cyanamide and its derivatives, condensation products of arcmatic hydrocarbons and phenols solubilized with sulfonic acids, mixtures of synthetic tannin terials and mixtures of syntans with other tanning agents. The syntans are preferably used in the form of their salts or in partially-neutralized form, for due consideration must be given the pH of the solutions used to treat protein on solid particles, so as not to attack or appreciably alter the fundamental properties of the solid. Other substances known to precipitate proteins, such as picric acid, quinone, or aldehydes. are also effective.
In general, the amount of tanning agent required depends upon the amount of protein to be fixed. It appears desirable to use sufficient tanning material to react with all or a substantial portion thereof. In the preferred compositions there is used from about one-fourth per cent. to about five per cent. of any of the tanning agents, based on the weight of material to be dispersed.
The powders or finely divided solids, which may be treated by this Process for improving the dry dispersion, include practically any soluble or insoluble material which can be prepared in powdered form. Such insecticides as lead, copper, calcium or magnesium arsenates are effectively rendered dispersible for use in agricultural or horticultural dusts. Likewise, fungicides, such as cuprous oxide, basic copper sulfate, copper sulfate pentahydrate or monohydrate, basic copper chloride, cuprous cyanide, and basic copper salts prepared with other elements such as calcium, magnesium or zinc, become easily dispersible in dry mixes after they have been treated by my process. Dry pigment mixes are greatly improved when one or more of the ingredients have been treated. Tints and toners may be treated for incorporation with white pigments, such as lithopone. Frits for enamels may be improved by treating one ingredient or more according to my process before dry mixing of materials. Pigments for tinting such diversified products as cement or face powder give more uniform results with better color values when treated with protein and tanning agent. Solids of high dispersibility are likewise desirable in numerous other applications such as in baking powders, dentifrices, powdered food products, and similar products which for one reason or another cannot conveniently be wetmilled.
In order to determine the effectiveness of the protein-tanning agent treatment, it was necessary to develop a method for testing dispersibility. No simple and precise method for the accurate evaluation of dispersibility of a component of a dust has heretofore been proposed. Obviously, any method which introduces an extraneous material or new component, such as oil, grease, water, or solution may change dispersion in the system significantly. One must adhere, therefore, to an examination of the dry dust. A technique, based on this consideration, was developed. By following it, one may mak comparisons and characterize the dispersion in practically any mixture of dry ingredients.
The standard test consists in taking a fixed weight of the material under investigation (5 grams) and mixing it with talc, whiting, Or any other desired diluent or mixture of diluents grams) in a 500 ml. bottle or jar by shaking or rotating the bottle or jar at a fixed rate for a given time. In my work it was found that a tumbling period of five minutes at 37 R. P. M. was satisfactory and gave reproducible results. A small mound of the mixed powder is formed and a spatula or knife drawn across the pile. A perfectly mixed dust shows no streaks or spots, but poorly mixed dusts will show a large number of streaks from poorly dispersed particles or agglomerates. If the material is colored, as in the case of copper compounds mixed with a lightcolored or White diluent, there will be no difficulty in observing the streaks because of the red, blue, or green or other color on a white background. In some cases it has been found that non-homogeneity may be more readily detected if the streaked mixture is exposed to ammonia fumes for a short period. In the case of zinc oxide, the streaks become evident under ultraviolet light. Another way to appraise the dispersion of white powders in dusts is to tint the diluent with a dye and observe the white streaks in a colored background.
The degree of dispersion of the mixed solids is best evaluated on a comparative basis. A numerical scale is conveniently applied, 1 being best, 2 next best and so on.
Treatment of typical powders, pigments, and dusts is shown in the following examples.
Example 1 A batch of red cuprous oxide, prepared electrolytically, was divided into four lots, each f which was treated in a different way, as will be deto serve as a control.
process herein disclosed. Each lot was taken up in hot water so as to form a suspension of 100 parts in 500 parts of water. The first lot was filtered, dried at 110 C. in vacuo, and powdered The second lot was treated with 0.5 part of glue in a concentrated solution, was well stirred, filtered, dried in vacuo at 110 C. and powdered. The third lot was treated with 0.5 part of glue in solution, just as the second lot had been, and then treated with a concentrated solution of two parts of commercial aluminum sulfate 17 A1203), which was added slowly with constant stir ring. At the end of 30 minutes, the suspension was filtered, the press cake dried at 110 C. in vacuo and powdered. Analysis of the product showed 0.07% A120 The fourth lot was treated directly with 2 partsl of alum in solution. After 30 minutes this suspension was filtered, the press cake dried at 110 t 0. in vacuo and powdered.
Tests of the dried products from each lot were made. The stability to oxidation of the gluetreated material (lot No. 2) and the glue-alum treated material (lot No. 3) was very high and similar for the two lots, as shown by exposure to air at 100 F. and at 95% humidity for a long period of time in atropical chamber. The preservation of cuprous oxide with glue and the testing of the stability of cuprous .oxide are described in U. S. Application Serial No. 190,036 filed February 11, 1938, which on December 26, 1939, issued as United States Patent No. 2,184,617. Lots Nos. 2 and 3 showed the same fungicidal activity when used as anti damping oif agents on seeds, as shown by germination tests. Lots No. 2 and No. 3 showed excellent dispersion in water. But lot No. 3'was outstanding in dry dispersion tests, in which 5 "grams of each product was mixed with 95 grams of clay by the standard, uniform procedure. These tests are summarized in the following table.
Treatment Rank order of dispersion Lot No.
wh ne- 'The difference between lot No. 3 and any of the others-was marked and greater than differences to be observed among the other lots.
Example 2 alum (17% A1203) in one-half gallon of water.
After the water was filtered ofi, the product was dried in an oven on trays at 90 C. and ground in a hammer mill. By the standard test the powdered product was more easily dispersed in talc than the same cuprous oxide treated only with glue.
The cuprous oxide carrying a tanned protein was compounded in dusts for parasiticidal applications and tested on a variety of plants, such as cucumber, muskmelon, squash, tomato, potato, and ginseng. A mixture of six pounds of the treated oxide in 94 pounds of talc was found to replace 20-80, -75, or -70 monohydrated copper sulfate-lime dusts. Lime injury, shown by curlingand distortion of leaves, dropping of blossoms. .dwariing of plants, and burning, was entirely avoided and there was, likewise, freedom from necrotic areas 'due to agglomerates of copper compounds. The control of diseases, such as blight on celery and potatoes and Septoria leaf spot on tomatoes, was unusually satisfactory.
Another dust was prepared with six pounds of cuprous oxide prepared as shown above, ten pounds of treated calcium arsenate prepared as will be described in Example 7 ,five pounds of flour and 79 pounds of talc as-a diluent. This mixture was particularly effective against fungus and chewing insects, such as the.potato beetle, the striped cucumber beetle, etc. and was an ex cellent repellent for leaf hoppers and flea beetles. The, homogeneity of the dust made with materials carrying tanned proteins was superior to dusts made with untreated materials. Also the dusts with treated materials were definitely superior in that they did not cause phytocidal ac- Superiority was also found for dusts containing six parts of cuprous oxide, five parts of flour, fifteen parts of powdered derris (5% rotenone content) and 74 parts of a diluent consisting of clay and talc, when the oxide carrying tanned protein was used. 3
' v Example 3 Red cuprous oxide, 250 parts, was taken up in 1000 parts-0f warm water. A water solution of lpart of glue was added and the mixture thoroughly stirred. A solution of 1.25 parts of zirconium oxychloride (0.47 part ZrOz) in 25 parts of water was then added and the mixture stirred for about thirty minutes. The slurry was filtered, dried in an oven at C. in vacuo and ground.
In a similar way samples of cuprous oxide were treated with glue and thorium nitrate, with glue and cerium sulfate, with glue and chromium sulfate, with glue and ferric chloride, etc. In all cases there was a marked improvement in dis-" persion of the treated cuprous oxide in dusts.
Example 4 A slurry of cuprous oxide was made with 250 parts of oxide in 1000 parts of warm water, one
part of glue in solution was stirred in, and then 4 parts of commercial tannic acid added. After the mixture had been well stirred, it was filtered, the press cake dried in an oven, and the dried material ground. The final product produced highly homogeneous mixtures with dry diluents,
such as clay, talc, magnesia, and chalk. It was definitely more dispersible in these diluents than samples made with glue alone or tannic acid alone. Example 5 Example 6 200 parts of zind oxide was suspended in 500 parts of water. A solution of 0.5 part of glue in 20 parts of water .was stirred in very thoroughly. Then a solution of 2.5,parts of commercial aluminum sulfate in 20 parts of water was slowly added with continuous stirring. The suspension was allowed to stand for two hours with occasional stirring. The oxide was filtered off, dried at 140 C. and ground.
The treated zinc oxide was dispersed in talc which had been dyed pink. It was observed that the treated oxide was more readily and completely dispersed than the untreated zinc oxide.
Example 7 200 parts of a calcium arsenate, such as sold for insecticidal purposes, was suspended in 500 parts of water, A solution of 0.5 part of glue in parts of water was thoroughly stirred in. Then a solution containing 2.5 parts of commercial aluminum sulfate in parts of water was slowly added while stirring was continued. The suspension was left standing for an hour and then filtered. The press cake was dried at 100-110 C. and powdered by grinding. Mixing experiments with dyed talc indicated clearly that the calcium arsenate treated with glue and alum was dispersed more readily than the untreated calcium arsenate, or calcium arsenate treated with glue alone or with alum alone.
Example 8 A slurry of 200 parts of flowers of sulfur was made in about 500 parts of water and thereto was added one-half part of glue dissolved in a little water. After the slurryhad been stirred for fifteen minutes, a concentrated solution of 2.5 parts of the sodium salt of naphthalene sulfonic acid condensed with formaldehyde was added and the slurry well stirred again. The suspension was then allowed to stand for thirty minutes, after which it was filtered and air dried at 60 C. for ten hours. The treated sulfur was ground into clay and was much more readily dispersed than the original sulfur or than sulfur carrying glue or the syntan separately.
Example 9 Ground sulfur carrying a small amount of calcium phosphate was treated as described in Example 8 except that one-half part of egg albumen was used in place of glue and eight parts of a solution containing a syntan made according to U. S. Patent No. 2,129,553 and assaying 12.5% tans was used in place of the condensed naphthalene sulfonate. The dried product was ground, sifted, and mixed with talc. Dispersion was greatly improved by the treatment given the sulfur.
Example 10 A suspension of 100 parts of red iron oxide pigment was prepared in 500 parts of water and one-half part of glue was stirred in. A solution of 2.5 parts of neutralized condensed naphthalene sulfonic acid in 20 parts of water was added with stirring. The mixture was allowed to stand for minutes; the iron oxide was removed by filtration, dried, and ground.
Example 11 The treatment of iron oxide described in Example 10 was repeated with substitution of egg albumen for the glue and the syntan used in Example 9 for the condensed naphthalene sulfonate.
The iron oxides prepared in Examples 10 and 11 were tested in talc. Both preparations showed improved dispersibility. The two samples were similarly dispersed in a dry calcimine wall paint.
aaoasoe The treated oxides were more evenly and more uniformly dispersed therein than untreated oxide. tinted with treated and untreated oxides. The lots of plaster to which treated oxide had been added were definitely superior to samples containing untreated oxide in distribution and freedom from agglomerates of tinting material. The oxides were likewise dispersed in Portland cement. Not only were more even distribution of particles and freedom from streaking obtained, but the color obtained with equal weights of the different oxide samples in a given weight of cement was definitely darker.
Example 12 A suspension of parts of ground derris root was prepared in 100 parts of water and onehalf part of soluble egg albumen added. The suspension was warmed to 50 C. and one-half part of condensed naphthalene sodium sulfonate added. After 30 minutes the suspension was filtered and dried at 60 C. The treated derris was definitely superior in dispersibility to untreated derris and uniform mixing of derris and talc was more readily obtained.
Example 13 A slurry of 100 parts of yellow cuprous oxide was made in 250 parts of water and a concentrated solution containing one-half part of bone glue added and stirred in well. After the slurry had stood for about 30 minutes, a solution of 1.5 parts of zirconium oxychloride in denatured ethyl alcohol was added. The mixture was stirred, filtered off, and the treated solids dried in vacuo. 'Dispersibility was superior to un treated cuprous oxide or glue-treated oxide,
Example 14 Commercial titanium dioxide (100 parts) was taken up in water (1500 parts) and a solution of commercial glue (5 parts) added. After the suspension had been agitated for a short time, sodium alum (7.5 parts) in water (20 parts) was added with good stirring. The treated titanium dioxide was filtered ofi, dried, and ground.
A second lot of titanium dioxide was slurried, filtered, dried, and ground by the same procedure, but without the addition of the treating re agents, and used for comparison.
These two lots of titanium dioxide were tested in compositions used for acid-resisting porcelain enamel frits. Batches of 35 pounds each were prepared according to the following formula After these ingredients had been weighed out, they were added to a Day mixer which was run fifteen minutes for each batch. The frits were then smelted at 2200 F. and poured as soon as the evolution of gas had ceased.
It was observed that there were fewer black A white patching plaster was likewise encased species due to titania in the fruit prepared with titanium dioxide treatedaccording to the process herein disclosed. When titania is agglomerated in frits, there-is a marked tendency for the oxide to yield black specks which are objectionable in the finished enamel. Although prolonged smelting helps to destroy the black specks.-
such treatment has a deleterious effect upon other properties of the frit. Emcient and uniform preparation of the pre-mixes save time,
labor, and material and produce frits of superior properties.
Example the zirconium oflchloride and drying was per-- formed at room temperature.
Dyed talc was used as the diluting medium for the dispersion tests. Finer particles and more .uniform distribution were obtained with the tanned salt than with alcohol-precipitated but untanned salt.
The process of treating finely divided solids withv a lyophilic protein colloid and a tanning agent permits better andmore uniform mixing of dry powders. Thus, when pigments are.mixed in a dry way, advantages, such as better coloring power, more even tinting, and freedom from A 5000 gram batch of antimony oxide was treated similarly but without addition of glue or alum. Thisbatch was used as a standard of comparison.
The degree of dispersion of the two samples and the resulting improvement in ceramic frits were demonstrated by incorporating them in typical mixtures for frits and smelting under a carefully controlled, uniform procedure. mamination of the two frits at the end of a minimum smelting period showed definitely that the specially treated antimony oxide gave fewer brown specks of undispersed antimony control sample.
. Example 16 The application of the principles herein disclosed to the treatment or easily soluble materials is hereby illustrated:
(a) A solution of 150 g. of copper sulfate was made in about 250 ml. of hot water. A solution of 1.5 g. of glue in 15 ml. of water was added and the solution stirred. There was then added about 400 ml. of 2 1B denatured alcohol, which caused precipitation of salt and glue. The precipitate was allowed to settle and the clear liquid drawn oil. The wet solid was treated with a solution or 5 g. of zirconium oxyehloridln alcohol. After the lapse of an hour, the product was filtered and dried. A batch of copper sulfate was precipitated by alcohol without the treatment with glue or zirconium salt and used for comparison.
Equal weights of the two copper sulfates were mixed with talc and examined in the standard way. Exposure of the spread mixtures to ammonia fumes helped to establish that the tanned material was very much better and more uniformly dispersed.
Such dispersions are particularly advantageous for the preparation of dusts containing copper sulfate for use on plants. They yield unithan the streaking, result. Treated pigments and admixes I are more readily incorporated in cement, plaster,
or other dry solids. The process, for further example, may advantageously be applied to materials used in compounding rubber.
By the treatment of parasiticides with a protein and a tanning agent, the process being applicable to any insecticidal or fungicidal agent, a definite improvement results in the dispersibility of toxicants' to be mixed with dry diluents used for agricultural and horticultural dusts. Improvement in dispersion is also noticed when these toxicants are applied in aqueous sprays.
Improved dispersion is of value because more uniform, complete and effective coverage of plants and parasites is thereby secured. Be-
cause better distribution of-toxicants treated in accordance with the described process may be obtained, it is possible to use smaller amounts in the formulation of dusts. Not only does this result in a saving in.cost, but it is advantageous from the standpoint of spray residues.
1. The process of preparing a mixture of finely divided solids characterized by improved dispersion of solids. which comprises treating in a wet way a solid, which in the dry, untreated state normally tends to agglcmerate when mixed with a second finely divided solid, with a water-soluble lyophilic protein colloid to form a thin surface layer of protein thereon and then treating the solid with a mineral tanning agent, separating the thus treated-material, drying it, and intimately comingiing the dry, treated material with another finely divided, solid material.
2. The process of preparing a mixture of finely divided solids, one of which normally tends toagglomerate when dispersed in another finely divided solid, which comprises treating the solid which tends to agglomerate with an aqueous solution of glue to form a thin layer of glue there-.
on and then with a tanning agent selected from a member of the class consisting of mineral tanning agents, natural tannins, and syntans, sepa-. rating the thus treated solid, drying it, and intimately comingling the dry, treated solidwith another finely divided solid material. 7
3. The-process of claim 2 in which the tanning agent is a soluble aluminum salt.
4. The process of preparing a mixture of finely divided solids, one of which normally tends to agglomerate when dispersed in another finely divided solid, which comprises treating an a. wet way the solid which tends to agglomerate with a water-soluble lyophilic protein colloid to form a 5. A fungicidal composition of matter comprising a mixture of finely divided cuprous oxide in other finely divided solid material, said mixture being characterized by uniformity, freedom from agglomerates cf cuprous oxide, and the presence on the surface of said oxide of a thin film of a water-soluble lyophilic protein which has been rendered insoluble with a mineral tanning agent.
6. The composition of claim 5- in which the mineral tanning agent is aluminum sulfate.
'7. The process of preparing a mixture of finely divided solids, one of which is a finely divided water-soluble solid which in the dry, untreated state normally tends to ag lomerate when admixed with another finely divided solid, which 15 asoasoa comprises dissolving the water-soluble solid in a solvent, adding a. lyophilic protein colloid to the solution so formed, precipitating the solid along with the protein colloid by adding to the solution a second liquid which is miscible with the so--v lution but has less solubility for the dissolved solid than the solvent aforesaid, treating the precipitated solid with a mineral tanning agent dissolved in a liquid which is substantially a nonsolvent for the precipitated solid, drying the solid carrying the protein colloid and tanning agent, and intimately comingling the dried solid with another finely divided solid.