US2433783A - Protein and drying oil emulsions - Google Patents

Description

Patented Dec. 30, 1947 PROTEIN AND DRYING OIL EMULSIONS William Pater-ck, St. Paul, Minn., assignor to 'Archer-Daniels-Midland Company, a corporation of Delaware No Drawing. Application July 26, 1944, Serial No. 546,749

9 Claims. (01. ins-143) This invention relates to protein and drying oil emulsions.

The emulsions are useful in providing a stable vehicle for clear, dyed, or pigmented coatings for use in the manufacture of wall board, paper, wallpaper, linoleum, and the like. Since the products are particularly satisfactory in water reducible paints, the invention will be described in detail in connection with the making of such paints.

In making water paints of the type .to whic the present invention applies, it is conventional to form an aqueous emulsion including a protein material, a fatty drying oil, and various miscellaneous ingredients. Miscellaneous ingredients frequenly include borax to promote dispersion or solubilizing of the protein, a preservative, an anti-foam agent, an anti-mold agent preventing molding of the protein, and glycerine to improve the brushability and flow of the composition.

A typical composition of the conventional type illustrated above, when cooked to 160 to 180 F., allowed to cool, pigmented, applied over a smooth surface, and dried for five days, showed a resistance to wet abrasion of 1,000 oscillations or somewhat less. (This test shows the number of oscillations or strokes which the dried film can withstand of a standard brush weighted to one pound and operated under running water. It is made according to the procedure of Federal Specification TT-P-88). After two weeks of incubation of the same paint at 95 F. in a closed chamber, the wet abrasion resistance of a film formed from it had been almost completely destroyed.

This loss of resistance to wet abrasion is characteristic of the usual protein and drying oil emulsions.

.In the effort to overcome this unsatisfactory resistance to wet abrasion, particularly after storage or incubation, it has been proposed to make the proportion of the drying oil to protein very large to replace the oil by a large proportion of varnish. The objection to this change in formulation will be readily appreciated when it is recalled that drying oil and varnish are more expensive than the protein, the present'price of the drying oil, for example, being 7 to 16 a pound as compared to 3 to 7 for satisfactory types of protein. Furthermore, the increased proportion of drying oil 'overtaxes the emulsifying power of the protein.

In addition the conventional emulsions are ordinarily stable only in alkaline condition and break when the alkalinity becomes low.

I The present invention provides a can-stable protein and fatty drying oil emulsion, suitable for use as a water reducible paint, that even after incubation and storage gives a film that is satisfactory in wet abrasion resistance, the resistance in typical specimens running as high as 4,000 oscillations. The invention provides also a composition that is stable at pHs on either the acid or the alkaline side of '7 providedthe pH is not at the isoelectric point of the protein, namely, about 4.6.

Briefly stated, the invention comprises emulsions including an aqueous solution of a protein, a dryingoil, a preservative, and ammonium chloride in addition to the usual miscellaneous and minor ingredients incorporated for their conventional efiect. The drying oil is added either as the protein is bein dissolved in the water or later, to give the finished protein and oil emulsion such as one suitable for use in a water paint to which the invention is particularly directed. In the preferred embodiment, the composition includes also sodium fluoride, it being understood that the fluorine andthe ammonia component may be added separately or together, as in the form of ammonium fluoborate.

As the protein used, that derived from soybean is particularly recommended because of satisfactory properties and low price. be used soybean meal, soybean flour, or deoiled and dehulled ground soybeans analyzing about 53% protein. Other proteins that may be used are cottonseed meal, peanut meal, isolated soybean protein and casein. These proteins may be used alone or in mixture with each other. A particularly satisfactory protein mixture is one consistingof of the ground soybean product (containing about 53% protein) and 25% casein. In such a combination, the soybean protein causes easy reduction with no foaming, while the casein contributes better brush application properties over thirsty surfaces and overnight film hardness. The various proteins described are known to be soluble in aqueous alkali, that is, dispersible in aqueous solutions of alkalies to give either a true or a colloidal solution.

The drying Oil used is any oneof those that is commonly used because of drying properties in protein and drying oil water reducible paint compositions. Linseed oil is ordinarily used as it is readily'available and satisfactory in properties. Other drying oils that may be used are soybean, fish, perflla and tung oil. The drying oil used may be mixed with a small proportion of plasti- Thus, there may cizing material as. for example, a few percent of lanolin onthe weight or the drying oil.

A preserving agent is incorporated. This agent stabilizes the emulsion. While there may be used customary preserving agents such as an alkali metal formate or benzoate, an alkali metal fluoride is particularly recommended for use with the added ammonium chloride. Sodium fluoride is the agent used commercially.

The ammonium chloride seems to be specific for the purpose of increasing the wet resistance and no alternative for it that is available at a reasonable price is known. However, ammonia may be added in the form of another salt, say as a double salt or as a reaction product of ammonium chloride with any of the other ingredients of the composition.- Thus, ammonium fluoborate may be added to replace apart at least of the borax, sodium fluoride and ammonium chloride. Also, the ammonium chloride may be formed in situ, as by reaction of hydrochloric acid and ammonia added separately. There is no point in using the more expensive ammonium bromide or iodide, although they may be substituted for the chloride if cost is not an object.

Water is used as the suspending medium in amount to give the desired concentration of the protein and drying oil materials and the proper consistency of the product. Ordinarily there is used about 1 to 4 parts of water for 100 parts of protein in the finished protein-oil emulsion. More water may be added when the emulsion is pigmented to form a paste paint.

In addition to the main and essential ingredients described above it is necessary in making a commercially satisfactory and stable composition to include additional or minor ingredients serving their usual functions. Thus, there should be included a solubilizing agent for the protein, examples of which are borax, sodium carbonate and sodium hydroxide, the last if selected being used in very small proportion. Also there must be used preservatives and an agent to decrease the foaming. Pine oil is a good preservative and anti-foaming agent. Methyl stearate and n-octyl alcohol are other examples of anti-foaming agents that may be used. A satisfactory antimold agent is sodium pentachlorphenate. Others that may be used are sodium orthophenylphemate, and sodium chlorophenylphenate. Glycerine, glycol, diethylene glycol, or other polyhydric alcohol is used to advantage to improve the brushability and working properties of the emulsion. Conventional accelerators of oxidation of drying oils, namely, paint driers of usual kind are incorporated in about the usual ratio to the oil present. Of these minor elements, certain ones may serve two functions. Thus the pine oil is an anti-foam and a preservative.

As to proportions, considerable variation is permi'ssible.

causes the emulsion to "oil out, that is, undercreaming. This effect is obviously undesirable. Too small a proportion of ammonium chloride, on the other hand, results in inferior resistance to wet abrasion and rapid deterioration of this property during storage or incubation. Once there is known the effect of the use of ammonium chloride, within the range of proportions stated, upon emulsions including the drying oil and protein, the best amount of ammonium chloride for any particular protein and drying oil composition is readily ascertained by making a few compositions of varying percentages of ammonium chloride within about the ranges stated above, and then determining the wet abrasion resistance of the several products. both before and after incubation, say at 95 F. in a closed container for two weeks.

The other conventional ingredients are used in about the proportions ordinarily found in the protein and drying oil compositions of water reducible paints. Suitable proportions of these other ingredients are illustrated in the specific example which follows.

EXAMPLE In'the practice of the invention, the followin order of mixing and proportions have been used to advantage.

Ingredient B i Parts Finely divided soybean protein (53% protein) 250 Mia: c

Parts Borax 5 Sodium pentaohlorphenate (preservative) 10 Water 750 Mia: D

Parts 125 10 The non-aqueous ingredients of Mix A are stirred into the water, after which there is incorporated the soybean protein constituting ingredient B. A short soaking period after the Drying nil Lanolin incorporation of the protein is desirable but may Because of the improving effect of the ammonium chloride, the proportion of the drying oil may be kept low, with resultant economy in cost of the formulation. Thus, drying oil is used in the proportion of 25 to 75 parts and, for especially satisfactory commercial results at low cost, about 40 to 60 parts for 100 parts of the protein material.

The ammonium chloride is'added in the proportion of about 8 to 20 parts for 100 parts of the protein. A large proportion of the ammonium chloride is advantageous in giving the maximum wet abrasion resistance. However, the use of ammonium chloride in too large a proportion be omitted.

Mix 0 is then introduced into the combination of Mix A and the soybean protein, the borax and pentachlorphenate being first dissolved or suspended in the water present.

Finally Mix D consisting principally of the drying oil is stirred into the combination A, B, and C.

The entire mass is heated momentarily to F. with constant agitation. The whole is then allowed to cool.

The resulting emulsion may be used either with or without the addition of pigment.

This emulsion, when pigmented, applied and tested for resistance to wet abrasion according to the standard procedure referred to above, gave a film which did not rupture appreciably with 4,000 oscillations of the standard weighted brush. Furthermore, the paint will tolerate long periods of storage or'incubation without loss of high resistance to wet abrasion.

Various orders of mixing of the several ingredients maybe used, so long as the order and the method chosen is one that gives a good smooth and uniform emulsion of the drying oil with the protein and other ingredients including the very large proportion of water.

At any suitable stage during this mixing there may be and should be introduced the paint driers of which lead and cobalt naphthenates are satisfactory.

As pigments there may be introduced lithopone, titanium oxide, or the like, either with or without inerts such as china clay.

Emulsion paints made as described are stable. After five months incubation at 95, they have shown no signs of spoilage, putrefaction, gas generation, loss of water resistance or change in physical properties upon storage. The dried film after incubation withstood 4,000 strokes without rupture, using the wet abrasion test described.

These paints have'good adhesion, hardness and flow.

The incorporation of the drying oil may be omitted in the initial compounding of the emulsifier composition. Thus, in the example, Mix D may be omitted from the initial preparation. There is thus produced a protein emulsion into which the drying oil, either with or without lanolin, is later emulsified.

It will be understood that it is intended to cover all changes and modifications or the examples of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope oi! the in-- vention.

What is claimed is: I v

1. A water reducible paint comprising an emulsion of an aqueous alkaline solution 01' a protein that is soluble in aqueous alkali, a fatty drying oil, a preserving agent for the protein, and ammonium chloride in the proportion of about 8 to 20 parts for 100 parts of the protein, the

protein being in proportion in excess of thatof 3. A composition as described in claim 1, the preserving agent .being sodium fluoride.

4. A composition as described in claim 1 including an anti-foam agent, a pigmentary material, and a paint oil dryer, the proportion of the drying oil being 25 to parts for parts of the protein.

5. A composition as described in claim 1 the protein being a finely ground-non-isolated soybean protein containing about 50% protein and the proportion of it including non-protein material being in excess of the drying oil.

6. A water reducible paint comprising an emulsion of the following materials in about the proportions shown: soybean protein 100 parts, linseed oil 50, sodium fluoride 8, ammonium chloride 10, pine oil 10, borax 2, sodium pentachiorphenate 4, lanolin 4, and water 500, all proportions being expressed as parts by weight.

7. A composition as described in claim 1, the protein material being a mixture of soybean pro tein and casein,

8. A composition as described in claim 1, the protein material being casein.

9. A composition as described in claim 1, the protein material being a mixture of non-isolated soybean protein and casein in the proportion of .The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Schuler Apr. 21, 1942 Number Harford Aug. 1, 1939 Atwood Jan. 10, 1933 FOREIGN PATENTS Country Date Great Britain Apr. 30, 1925 Australia 1935 Great Britain 1912 OTHER REFERENCES United States Government Paint Specifications-Circular 718, page 144--Scientiflc Section, National Paint, Varnish and Lacquer Association, Inc., Dec. 1946.

Number Scholz et al. Sept. 30, 1941 Dunham May 27, 1923