US2412819A - Detergent briquette - Google Patents

Description

Patented Dec. 17, 1946 James Douglas MaeMahon,

lsnor to The Math] a corporation of Virginia as New York, N. Y.,

Niagara Falls, N. Y.,

eson Alkali Works, Inc.,

No Drawing. Application July 21, 1945,

Serial No. 606,481

6Claims.

This invention relates to improved briquetted detergent compound. The briquette of my present invention is unique in its combination of detergent characteristics and other physical and chemical properties which make it highly satisfactory for use in modern mechanical washing operations.

Modern mechanical methods and apparatus for washing dishes, milk cans and the like, particularly where the operation is continuous or prolonged, have presented the serious problem of maintaining an alkali concentration in the wash tanks between desirable and restricted limits. Commercial experience has shown that this may be accomplished in a dependable and virtually automatic manner by dissolving alkaline briquettes in suitable auxiliary equipment and dispensing the resulting solution into the wash tanks at a predetermined rate. A very considerable amount of research has been carried out in view of developing detergents having chemical and physical characteristics satisfactory for this purpose.

The problem presented involves not merely the production of a material or mixtures of materials having the desired detergent characteristics but also the development of a product which, in addition to meeting that requirement, can be economically produced in the desired physical form possessing other essential physical characteristics.

For instance, it is desirable that the detergent be in briquette form; that the briquettes be sufiiciently hard and strong to withstand ordinary handling; be chemically and physically stable and non-deliquescent so as to withstand storage and the necessary handling and of such structure as will not disintegrate under the conditions of use. l

Inasmuch as the control of the rate at which the alkali is dispensed into the washing operation largely depends upon the dissolving rate of the briquette, it is desirable that the briquette not only have a satisfactory degree of uniformity in its composition but also that it have a uniform solubility rate.

It is, of course, also essential that the composition of the cleansing solution be such as to avoid harmfully afiecting the material being washed either by attacking the material or by forming deposits or coatings thereon. It is further essential that the composition of the detergent be such as to avoid deleteriously affecting the parts of the mechanical washer and the deposition of scale in the various chambers thereof.

It has been proposed to produce detergent chanical washers briquettes for such use by fusing the detergent or detergent mixture and casting the fused material by drawing it oif into molds to cool. For example, briquettes have been produced by fusing mixtures of trisodium phosphate and soda ash. However, the relatively high temperatures required to fuse the detergent or detergent mixtures have been a decided handicap in the production of satisfactory detergent briquettes, as many substances, the presence of which is highly desirable in detergent mixtures, are driven off or decomposed at temperatures below their fusion point or at temperatures necessary for fusing other desirable constituents.

This temperature requirement has not permitted the incorporation in detergent mixtures so produced of many very effective water conditioners and surface active agents such as synthetic detergent and wetting agents. Consequently, the use of such fused detergent briquettes has not been wholly satisfactory. For instance, particularly under adverse water conditions, their use has resulted in the precipitation of natural hardness of the water supply and the tendency to form scale on the inner surfaces of the mewith which the detergent is used. Rapidity of this scale formation depends upon the degree and nature of the hardness of the water and, in general, increases with the concentration of hardness of the water supply. If not periodically removed, this scale interferes with the normal functioning of the equipment. Further, this precipitated hardness interferes to a greater or less extent with .the' cleansing operation.

The presence of a water conditioner such as a sodium polyphosphate, for instance sodium tripolyphosphate, in the alkaline solution tanks of the mechanical washers has been found to inhibit or greatly retard scale formation. Also, the addition of surface active agents has been found further to enhance the cleansing action and to afford improved rinsing. However, for the reasons stated above, the incorporation of these materials in fused anhydrous detergent briquettes has been impractical.

Detergents have heretofore been produced in block form by crystallization or solidification of the detergent or detergent mixtures from aqueous solutions; for instance, by the evaporation of water therefrom or bycausing a chemical or physical union of the water or a proportion thereof with the detergent. The resulting blocks of detergent material have usually been reduced to a granular or powdered form before use.

It has also been proposed to use these detergent blocks as such in detergent operations. However, so far as I am aware, the detergent blocks so produced prior to my invention have fallen short of the requirements essential to their satisfactory commercial use in mechanical washing operations.

The detergent briquette of my present invention may be formed without resort to high temperatures and its constituents and proportions thereof may bevaried over a considerable range to meet the requirements of the particular washing operations in which it is to be used. Further, the physical limitations and deficiencies common to previous detergent briquettes are overcome. My improved briquettes consist of a dense crystalline aggregate of-relatively uniform composition. They are hard and strong and physically stable, beingcapable of withstanding the conditions of shipment and storage essential to ultimate commercial use without material deterioration, disintegration or deliquescence. They do not disintegrate under normal conditions of use and have a uniform solubility rate. Further, there is no objectionable chemical change in the composition of the briquette. Also, since they can be produced without resort to high temperatures, various desirable addition agents unstable at higher temperatures may be incorporated therein to meet special water conditions or detergent requirements. Accordingly, objectionable precipitations of natural hardness of the water used may be inhibited or greatly reduced and the detergent action of the resulting washing solution materially improved. Further, the congealing and hardening time of my briquettes during molding is sufliciently rapid to permit their economical commercial production.

The detergent mixtures of which my improved briquettes are composed are prepared by mixing with sodium silicate in the manner and proportions'hereinafter fully described various materials previously known to have detergent or waterconditioning properties. My invention is predicated on my discovery that various combinations of such materials, in proportions hereinafter described, may be compounded with the sodium silicate to form briquettes having the above-noted desirable characteristics and without resort to objectionably high temperatures.

In Patents Nos. 2,382,163 and 2,382,165, issued August 14, 1945, on my co-pending applications,

Serial Nos. 429,127 and 429,129, each filed Janu-.

ary 31, 1942, as continuations-in-pa'rt Of my application Serial No. 389,619, filed April 21, 1941, I have described and claimed briquettes comprising sodium silicate, of which the NazO:Si02 ratio is not less than 1:1, nor greater than 2:1, trisodium phosphate, sodium carbonate, water, and a phosphate water conditioner. These briquettes contain 30% to 40% of water as an essential ingredient. Other essential ingredients and proportions thereof of the briquettes described and claimed in Patent 2,382,163 are 1-15% trisodium phosphate, 1-25% of the sodium silicate, 20-50% of sodium carbonate, and 3-25% of tetrasodium pyrophosphate.

Essential ingredients of my briquette of Patent 2,382,1'65fin addition to water, and proportions thereof are as follows: 1-35% trisodium"phosphate,'1-25% of the sodium silicate, -50% of sodium carbonate, and 1-15% of sodium hexametaphosphate or sodium tetraphosphate.

Thus it appears that trisodium phosphate, sodium silicate and sodium carbonate, are essential ingredients of each of these types of briquettes.

However, by reason of some unexplainable peculiarity of the particular phosphates used, the permissible ranges of proportions of the trisodium phosphate and of the sodium carbonate may be materially extended in the second type,

The physical characteristics of the briquettes are of major importance and the necessity of attaining the essential physical characteristics has heretofore placed objectionable limitations on the composition of the briquette with respect to ingredients and proportions thereof. These limitations have been a deterrent to the attainment of briquettes having optimum detergent characteristics, for some special purposes, and also from a standpoint of cost and availability of certain of the essential ingredients.

In Patent No, 2,382,164, issued August 14, 1945, on my co-pending application Serial No. 429,128, filed January 31, 1942, as a continuation-in-part of my earlier application Serial No. 389,619, I have disclosed and claimed a briquette which affords material relief from the limitations just described but whichinvolves the use of a sodium silicate in which the NazOzSiOz ratio is less than unity.

In accordance with the invention therein described, either the trisodium phosphate or the sodium carbonate may be entirely omitted or may be usedin proportions aggregating 50%-60% of quette in which either the trisodium phosphate or the soda ash may be omitted or may be present in proportions aggregating about one-half the total formula weight but which has the further advantage that a sodium silicate of higher alkalinity, that is, one in which the NaaOzSiOrratio l is equal to 1 or up to as high as 2, may be used.

In accordance with my present invention, these advantages are attained by incorporating in the briquette a substantial proportion of sodium tripolyphosphate (NasPsOro) In addition to its effect upon the physical characteristics of the briquettes, the sodium tri-. polyphosphate has been found to be an excellent water conditioner and materially toimprove the detergent characteristics of the resultant briquette. It has also been found favorably to influence the molding characteristics of the briquette.

The essential ingredients of the briquette of I my present invention are sodium tripolyphosphate, either trisodium phosphate or soda ash,

-water, and sodium silicate having an alkalinity equal to the metasilicate or higher. In addition to these essential ingredients, various surface active agents capable of withstanding the com- .pounding temperatures in an alkaline environ- 'ment may be included in my briquettes to meet special conditions encountered in specific detergent operations for which the briquettes are intended. a For this purpose I have used with advantage a product consisting principally of sodium lauryl sulfate marketed under the trade name 0rvus,or pneconsisting principally 9 sodium dodecyl benzene sulfonate marketed un hydrated product generally represented by the formula Na3PO4.12H2O or a product having a lower water content. Theoretically, the dodecahydrate contains 56.8% water, but the commercial product usually contains somewhat less than this amount. Where high proportions of trisodium phosphate are to be used, it may be desirable to use one of lower water content to avoid the introduction of too much water.

Materials that react under the process conditions to form trisodium phosphate, for instance disodium phosphate and caustic soda, may be substituted for an equivalent proportion of trisodium phosphate, appropriate allowance being made for the water content of such reacting materials and water produced by the reactions.

The sodium silicate constituent of my briquettes should have an NazOtSiOz ratio of not less than 1 nor greater than 2. I have obtained excellent results by supplying the sodium silicate in the form of water glass of 41 B. gravity, and consisting of 8.9% NazO, 28.7% $102 and 62.4% water, and reacting the water glass with caustic soda in suflicient proportions to produce a sodium silicate of the desired Nazozsioz ratio. Other water glass or sodium silicatein solid form may be used in accordance with my invention by making appropriate allowance for difierences in composition. For example, instead of the use of water glass and sufl'icient caustic soda to react therewith to form the metasilicate, sodium metasilicate as such may be substituted wholly or in part for the water glass and caustic soda equivalent. When such substitution is made, due allowance should also be made for the amount of water which would otherwise be formed by the reaction between the water glass and caustic soda:

The caustic soda may be suppliedin solid form such as the usual commercial grade of about 76% NaaO. However, other forms of caustic soda, such as the commercially available 50% solution, may be substituted provided appropriate allowance is made for the diiference in composition.

The sodium carbonate, when used, mayconveniently be supplied as anhydrous soda ash and the proportions stated in the several formulae appearing herein are based upon the use thereof. However, it may be supplied in the form of hydrates such as monoor decahydrates, appropriate allowance being made for difierences in composition. Similarly, the sodium tripolyphosphate may be supplied in the usual anhydrous form, and proportions thereof appearing herein have reference to such material.

Before further defining and illustrating the ranges of proportions of the various ingredients incorporated in my approved briquette, I shall describe a process which may be used with advantage in compounding and preparing the same.

The compounding of my improved detergent is advantageously carried out in a conventional steam-jacketed kettle equipped'with a stirring device. I have obtained excellent results in preparing and in duplicating the structure of the briquettes by adhering to the following procedure: The predetermined amounts of the sodium silicate, trisodium phosphate, caustic soda, and additional water, or such of these materials as are to be used, are placed in the kettle and heated with constant agitation until the mass is fluid. The temperature is then maintained below that at which evolution of steam would occur with a resultant loss in water content. Higher. temperatures than necessary are to be avoided,

The fluid mass is held at as it is desirable to reduce to a minimum the amount of water lost during the heating operation. The maximum temperature to which the material is heated, and at which it is held, depends primarily upon the concentration of the solution in the fluid mass and is usually found to be within the range of about 80 C. to 100 C. this temperature until maximum clarity is obtained. This usually requires from 10 to 20 minutes, depending upon the composition and amount of solute.

At this point, a predetermined amount of soda ash is added, if this constituent is to be used. and thoroughly mixed with the fluid mass. If the addition of soda ash results in a decrease in temperature and the mass becomes too viscous for final pouring, the temperature may be increased until adequate fluidity is obtained, care being taken to avoid temperatures which would result in the material loss of water. The tripolyphosphate is advantageously added and thoroughly mixed in the mass in the kettle just prior to pouring. The temperatureshould preferably be at a minimum for adequate pouring fluidity.

The mixture is finally drawn ofi into suitable molds and allowed to congeal until the briquette has developed suiiicient mechanical strength to permit its removal from the mold. The necessary molding time will generally vary from about 1 hour to several hours, depending upon the composition of the mixture.

On cooling, detergent compositions of this type seem to expand somewhat and this, combined with the tendency to adhere to metal surfaces of the molds, has previously presented considerable difliculty in the molding of detergent materials. I have found that, by using flexible briquettemolds such as molds made ofrubber or similar materials, these difllculties are eliminated.

When it is desirable to incorporate in the briquettes a so-called surface active agent, such material may be introduced into the mixture just I The proportion prior to withdrawal from the kettle. However, where such addition agent is in solid form and has a relatively slow rate of solubility, I prefer to add it prior to the addition of the soda ash.

The amount of water present in the detergent composition is of major importance with respect to molding time and mechanical structure of the resultant briquette and also its detergent capacity. It is essential that suflicient water be present during the processing to produce under processing conditions a mass sufllciently fluid to permit satisfactory mixing and pouring into the molds and have satisfactory molding characteristics. However, the addition of an excess of water is generally to be avoided since the processing normally does not involve conditions under which excess water would be eliminated.

I have found the permissible range of proportions of water in my briquetted product to be from about 30% to about 50% by weight. As above noted, it is necessary that the product contain suflicient water to permit satisfactory pouring and molding but an increased amount of water in the product results in a corresponding reduction in the alkali content of the briquette.

of water present also has a distinct efiect upon the physical characteristics of the briquette. Proportions of water in the product up to about 40% The optimum amount of water present in the.

finished product appears to depend to a considerable extent upon the proportion of other ingredients added. Usually, more satisfactory re-.- sults are obtained where the proportion of water is not much in excess of that required to give sufficient'fiuidity for molding, as hereinbefore described. In determining the quantity of water, if any, to be added as such in the compounding operation, due consideration must be given tothe amount of water present in thevarious constituents, either as water of crystallization or otherwise, and of water formed by chemical reactions.

A small amount of water may be vaporized or lost during the compounding of the detergent mixture, particularly if the higher temperature be used. The amount of water thus lost is usually of no particular consequence. However, if the amount of water thus lost is excessive,'additional water may be added to the batch. I have observed that where a surface active agent is used in proportions approaching the upper limit of the presently to be described range, there is a tendency toward a relatively more fluid mass in the kettle, and that under such conditions the proportions of water may be reduced slightly below 30% and still permit satisfactory pouring.

As previously noted, either the trisodium phosphate or the soda ash, but not both, may be completely omitted. Where one is omitted, the other should be-used in an amount not less than about one-tenth the formula weight. Similarly, where both are used, the amounts should aggregate not less than about one-tenth the formula weight. The aggregate amounts-of these materials may be as high as about one-half the formula weight, say 5060%, or either of these materials may be used in that amount.

Though the sodium silicate'is an essential ingredient of my present briquette, satisfactory' physical and chemical characteristics may be obtained using proportions of sodium silicate, of the type described, as low as about 1%, and where desirable, the silicate content may be increased to as high as about 15% without detrimentally affecting the physical characteristics of the briquette.

A briquette having satisfactory physical and chemical properties maybe prepared in accord-' ance with my present invention, using proportions of sodium tripolyphosphate as low as about 2%, and where desired, the proportion of this ingredient may be increased to about one-half the formula weight without detrimentally affecting the physical characteristics of the briquette. I

Where the presence of a surface active agent, such as previously mentioned synthetic detergents and wetting agents, is desirable, such materials may be incorporated in the briquettes in amounts ranging as high as about 5% of the active ingredient, though smaller proportions are usually sumcient for most purposes.

The addition of even a fraction of 1% of many of the so-called surface active agents. or synofthe resulting briquette. This effect has been found to increase generally as the amount of the agent is increased. Also, under similar conditions of preparation, the addition of some of these surface active agents somewhat increases proportions of sodium silicate.

the molding time. Though for some purposes a reduced dissolving rate is undesirable, the addition of a predetermined amount of a surface active agent isof value in controlling the dissolving rate to meet a specific requirement in this respect. However, the primary purpose of the surface active agent is to increase the wetting power of the washing solution and so tend to improve the detergent and rinsing properties thereof. The addition of these materials in proportions as small as 0.1% has been found to have a noticeable effect on solubility rate.

One of the advantages of my invention is that such surface active agents may be incorporated in my briquettes where desirable either for controlling the dissolving rate or for improving the detergency of the washing solution. However, under many conditions encountered, the detergent mixture need not be so supplemented. Various surface active agents may be used for this purpose. However, alkali-stable, non-saponaceous, synthetic, organic surface active agents have been found to be particularly desirable.

While the proportions of the various ingredients may be varied over a considerable range without destroying the desirable physical ;or chemical properties of the resulting briquette, I have found the permissible range of variation to be rather sharply defined. However, where the ingredients and proportions thereof are used in proportions within the herein described ranges, briquettes having satisfactory physical properties may be prepared to meet a wide variety of detergent requirements.

The following analyses are presented as specific illustrations of the proportions of the several constituents of the briquettes of my present invention. It will be understood, however, that my invention is not limited to products having the particular composition shown. In each instance the proportions indicated in the following tabulation, and elsewhere herein, are by weight and on an anhydrous basis.

- Sodium tripolyphosphate Soda ash Sodium silicate Total T. S. P.

Per cent Per cent Per cent Per cent Per cent In the foregoing Examples 1 to 9, sodium metasilicate was used. In Example 10, the alkalinity of the silicate approximated that of sodium sesquisilicate. These examples illustrate approximately the maximum and minimum For simplicity of comparison, the amount of sodium silicate used in the first nine examples has been maintained constant. Example 1 is further illustrative of a briquette containing approximately the minimum prescribed proportion of sodium in th say about 7 to 15%.

anaeig tripolyphosphate and approximately the maxisodium phosphate-and soda ash. Example 2 is illustrative of approximately the maximum pro- Y portion of sodium tripolyphosphate and approximately the minimum proportion of soda ash when no trisodium phosphate is present. Example 3 is further illustrative of a briquette containing no trisodium phosphate, and Example 4 is 11- lustrative of a briquette containing no soda ash. Examples 5 and 6 are illustrative of a briquette containing both trisodium phosphate and soda ash in intermediate proportions. Examples 4 and 7 further illustrate the approximate minimum and maximum proportions of water. Example 8is illustrative of a briquette containing approximately the maximum proportion of sodium tripolyphosphate, containing both trisodium phosphate and soda ash in proportions approaching the lower limit of the prescribed range, and Example 9 is illustrative of a briquette containing substantially the maximum proportions of sodium tripolyphosphate and containing no soda ash.

I have also found that the addition of a minor proportion, for instance about 5 to of sodium bicarbonate to the detergent mixture tends to improve its molding characteristics, particularly where the trisodium phosphate content is on the lower side of the prescribed range, say less than about 25%, and the silicate content is e upper portion of the prescribed range,

I claim:

1. A detergent briquette, physically stable, hard, strong and non-deliquescent, consisting of a dense crystalline aggregate consisting essentially of the following constituents in proportions by weight within the respective indicated ranges: Sodium silicate, of which the NazOzSiOz ratio is not less than 1:1 nor greater than 2:1, about 1-15%, total water about 30-50%, sodium tripolyphosphate about 2-50%, and at least one detergent of the group consisting of sodium carbonate and trisodium phosphate aggregating from about one-tenth to about one-half of the total formula weight.

2. A detergent briquette, physically stable, hard, strong and non-deliquescent, consisting of a dense crystalline aggregate consisting essentially of the following constituents in proportions by weight within the respective indicated ranges: Sodium silicate, of which the NagOzSiOa ratio is not less than 1:1 nor greater than 2:1, about 1-15%, total water about 30-50%, sodium tripolyphosphate about 2-50%, at least one detergent of the group consisting of sodium carformula weight, and about Oils-about 5% of an alkali-stable. non-saponaceous. synthetic, organic surface active agent.

. 1 3. A 7 detergent briquette, physically stable, hard, strong and no -deliquescent, consisting of a dense crystalline aggregate consisting essentially of the following constituents in proportions by weight within the respective indicated ranges: Sodium silicate, of which the Naz02$i0z ratio is not less than 1:1 nor greater than 2:1, about 1-15%, total water about 30-40%, sodium tripolyphosphate about 2-50%, and at least one detergent of the group consisting of sodium carbonate and trisodium phosphate aggregating from about one-tenth to about one-half of the total formula weight.

4. A detergent briquette, physically stable, hard, strong and non-deliquescent, consisting of a dense crystalline aggregate of the following constituents weight within the respective indicated ranges: Sodium silicate, of which the Nazozsioz ratio is not less than 1:1 nor greater than 2:1, about 7-15%, total water about 30-50%, sodium tripolyphosphate about 2-50%, at least one deterin proportions by gent of the group consisting of sodium carbonate and trisodium phosphate aggregating from about one-tenth to one-half of the total formula weight,

the trisodium content not exceeding about 25%,

and about 5-15% of sodium bicarbonate.

5. A detergent briquette, hard, strong and non-deliquescent, consisting of a dense crystalline aggregate consisting essentially of the following constituents in proportions by weight within the respective indicated ranges: Sodium silicate, of which the not less than 1:1 nor greater than 2:1, about 1-15%, total water about 30-50%, sodium tripolyphosphate about 2-50%, at least one detergent of the group consisting of sodium carbonate and trisodium phosphate aggregating from about one-tenth to about one-half of the total formula weight, and about 0.1-about 5% of an alkalistable, non-saponaceous, synthetic, organic, surface active agent, consisting principally of sodium lauryl sulfate.

6. A detergent briquette, physically stable, hard,

strong and non-deliquescent, consisting of a dense crystalline aggregate consisting essentially of the following constituents in proportions by weight within the respective indicated ranges: Sodium silicate, .of which the Na:O:SiOz ratio is not less than 1:1 nor greater than 2:1, about 1-15%, total water about 30-50%, sodium tripolyphosphate about 2-50%, at least one detergent of the group consisting of sodium carbonate and trisodium phosphate aggregating from about one-tenth to about one-half of the total formula weight, and about 0.1-about 5% of an alkalistable, non-saponaceous. synthetic, organic surface active agent, consisting principally of sodium dodecyl benzene sulfonate.

.mms Donor-As MacMAHON.

consisting essentially physically stable,

NazOzSiO: ratio is