US3118805A - Drying of hydrazinium salt solutions for packaging - Google Patents

Description

Jan. 21, 1964 P. MESSINA ETAL 3,118,805

DRYING 0F HYDRAZINIUM SALT SOLUTIONS FOR PACKAGING Filed July 12, 1961 PHILIP MESSINA SU TIONG PHOA INVENTORS BY zwzw j;

AGENT United States Patent 3 118,805 DRYING 0F HYDRAZINIUM SALT SGLUTIONS FOR PACKAGING Phiiip Messina, Hanover, and Su Tiong Phoa, Baltimore,

Md, assignors to W. R. Grace 8; (30., New York, N.Y.,

a corporation of Connecticut Filed July 12, N61, Ser. No. 123,446 2 Claims. (Cl. 159-47) This invention relates to the use of hydrazinium compounds as textile softeners. In one specific aspect, this invention relates to the drying of hydrazinium compounds in preparation for packaging as textile softeners.

Cationic textile softening agents are finding wide acceptance in both mill and home laundry application. Over 8,000,000 pounds of cationic finishing agents are used each year. It has recently been suggested that selected hydrazinium salts, owing to their inherent chemical properties, would be effective textile softeners. And indeed, this has been found to be the case. However, one of the big drawbacks is that most of the effective compounds of this group exist normally in the liquid state, and are consequently somewhat cumbersome to use. And even more important, the liquids are not easily adapted to the current popular packaging methods wherein powdered laundering compounds are sealed in individual water-soluble packages for easy, pre-measured addition to washing machines. The obvious solution to this problem is to dry these compounds, thereby rendering them suitable for use as a powder. But to date, this has not been successfully carried out in many compounds.

It is an object of our invention, therefore, to effect the drying of hydraziniums and related compounds in such a way as to render them useful as a powder.

It has been found that a simple but critical step must be added to the usual drying procedure where it is desired to pulverize the more difiicul-tly dried compounds. The material is satisfactorily dried by heating in a vacuum dryer, after which it is subjected to a cooling period. Here, the dryer acts as a pulverizer, changing the large pasty chunks ordinarily produced into a fine granular material. Thereafter, the material is reheated to dry it completely.

In accordance with our invention the compound to be dried is introduced into a vacuum rotary dryer at suificiently high temperatures to insure that said compound is in a fluid state. The jacket of the dryer is maintained at a temperature such that this will remain the case. Solvent is removed until the compound begins to foam or thicken. At this state, the temperature of the jacket is dropped below the freezing point of the compound. We have found that generally, ordinary tap water, in the order of 60 to 80 F. is low enough to bring about this change. At higher temperatures, the solids are waxy and do not tend to break up; on cooling, the solids become substantially hardened and break up on agitation. This reduced temperature is maintained for sufiicient time that the agitating action of the rotary dryer effectively breaks up all lumps and gives a fine, granular material. The temperature of the dryer is then raised to a point at which the remaining volatiles are efficiently removed. The invention is more readily understood by considering in some detail and comparing two compounds, 1,1-bis(perhydrotallow)-1-methyl hydrazinium chloride, and 1,1-dimethyll-perhydrotallow hydrazinium chloride. Of these two compounds, the former dries fairly readily, whereas the latter is ordinarily more difiicultly dried. The reason for this lies in the processes by which the two compounds are made.

3,118,805 Patented Jan. 21, 1964 In both cases, the process involves two main chemical reactions as shown below:

where R is a hydrogenated tallow (C -C or methyl radical and R is a hydrogenated tallow radical.

Reaction 1 shows the conversion of ammonia and chlorine to chlorarnine. Chloramine is then added to a tertiary amine to form the hydraziniur'n chlorides referred to above. Both of these reactions occur simultaneously in a solvent The molar ratio of ammonia to chlorine in the reaction is maintained at about 5:1 at all time to prevent the formation of undesirable and hazardous nitrogen compounds. The reaction proceeds with both gases sparging from a twin fluid nozzle until approximately 200% of the theoretical chlorine required to form the hydrazinium chloride has been added. At this point the reaction is usually complete. The chlorine flow is discontinued and, after a few minutes, so is the ammonia flow. Ammonium chloride is removed as a solid, after which the resulting filtrate is placed in a vacuum still. Here, solvent is evaporated from the solution at a liquid temperature of about 140 F. and an absolute pressure of 15 inches of mercury. It is desirable to operate at low temperature to avoid discoloration of the final product. Evaporation to about 70% solids level, at which point the material is still fluid, is complete in about 6 to 10 hours, and the recovered solvent is recycled.

The problem arises in the final drying step. In some instances, the drying is not difficult. For purposes of comparison, the drying of 1,1-bis(perhydrotallow)-1- methyl hydrazinium chloride is described as typical of the procedure where no particular difiiculties are encountered. The concentrated solvent at temperatures of 130- 140 F. containing approximately 70% by weight of the hydrazinium chloride is pumped or sucked into a rotary vacuum dryer by maintaining a slight vacuum on the dryer. Liquid is drawn into the dryer until a charge somewhat greater than 50% of the total volume is achieved. During this charging period the jacket is maintained relatively cool, usually below F. At the completion of charging, the vacuum is gradually increased to the maximum capacity of the vacuum system. The material is agitated during this period, but no external heat is applied to the jacket. Within 1 or 2 hours the liquid within the dryer will solidify to granules or chunks which eventually become a fairly smooth flowing powder. When solidification is complete, drying is continued by maintaining a temperature of about F. in the jacket and maximum vacuum inside the unit. Final volatiles are below 2% However, 1,l-dimethyl-l-perhydrotallow hydrazinium chloride does not dry as readily as the compound described above, and hence production of it is seriously affected. We have modified the drying procedure in the manner described as follows to achieve rapid, thorough drying.

Referring to the accompanying drawing, the concentrated liquid is drawn into a vacuum rotary dryer 1, driven by a motor 2 at -150 F. by employing the vacuum system. The jacket 3 is again maintained at about 100 F. or lower. The dryer is charged in this instance to somewhat less than 50% of the total volume and full vacuum is applied until the material forms a heavy pasty mass. In the case of this compound, as compared with the one described previously, the material does not go rapidly to a fine granular powder but does solidify in large pasty chunks. When the pasty mass is obtained the jacket temperature is increased, usually to about 165 F., and held there for about one hour while the entire mass is agitated. After the one hour period, cold water is introduced into the jacket 3 While still agitating the mass. The rotary vacuum dryer at this point really acts like a large pulverizer and the chunks are slowly ground into a fine granular material. Once this point has been achieved, heat is applied to the jacket 3 again to a maximum temperature or about 120 F. and the drying is continued to completion. The solvent evaporated from the solids is recovered from condenser 4. Final volatiles are below 2% The method set out above may be applied to other difficultly dried long-chain hydrazinium salts. As well, quaternary ammonium compounds already on the market as textile softeners but none in the dried form, could be reduced to dry dispersible powders by the same general technique.

We claim:

1. A method of reducing diflicultly dried hydrazinium salts to dispersible powders comprising drawing a concentrated solution of said hydrazinium salt into a vacuum rotary dryer at a temperature sufiiciently high to insure that the compound is in a fluid state, equipping said dryer with a water jacket having means for the ingress and egress of water and serving as a heat exchanger, charging said dryer to just under 50% of the total volume, applying vacuum to said dryer until said compound exhibits signs of solidification, maintaining said vacuum and increasing the temperature of said jacket to a temperature sufiiciently high to evaporate solvent efficiently maintaining said temperature until said compound begins to foam and thicken substantially, introducing water at a temperature below the freezing point of said compound into said jacket, continuing the agitation until the thickened mass is a fine granular solid, and reapplying heat to said jacket to completely dry said compound.

2. A method of reducing 1,l-dimethyl-l-perhydrotallow hydrazinium chloride to a dispersible powder comprising drawing a concentrated solution of said compound into a vacuum rotary dryer at 130 to 150 F., equipping said dryer with a Water jacket having means for the ingress and egress of water and serving as a heat exchanger maintaining said jacket of said dryer at about 100 F., charging said dryer to just under of the total volume, applying vacuum to said dryer until said compound forms a heavy mass, increasing the temperature of said jacket to about 165 F., agitating said mass at said temperature until said compound begins to foam and thicken, introducing water at a temperature of about -80" F. to said jacket with continued agitation of said mass until said mass is converted to a fine, granular material, and increasing the temperature of said jacket to about F. to dry said compound to completion.

References Cited in the file of this patent UNITED STATES PATENTS 668,159 Campbell Feb. 19, 1901 1,297,496 Rogers Mar. 18, 1919 1,831,049 Treschow Nov. 10, 1931 2,087,788 Thal July 20, 1937 2,716,052 Felger Aug. 23, 1955 FOREIGN PATENTS 818,431 Great Britain Aug. 19, 1959

Claims (1)

1. A METHOD OF REDUCING DIFFICULTY DRIED HYDRAZINIUM SALTS TO DISPERSIBLE POWDERS COMPRISING DRAWING A CONCENTERED SOLUTION OF SAID HYDRAZINIUM SALT INTO A VACUUM ROTARY DRYER AT A TEMPERATURE SUFICIENTLY HIGH TO INSURE THAT THE COMPOUND IS IN A FLUID STATE, EQUIPPING SAID DRYER WITH A WATER JACKET HAVING MEANS FOR THE INGRESS AND EGRESS OF WATER AND SERVING AS A HEAT EXCHANGER, CHARGING SAID DRYER TO JUST UNDER 50% OF THE TOTAL VOLUME, APPLYING VACUUM TO SAID DRYER UNTIL SAID COMPOUND EXHIBITS SIGNS OF SOLIDIFICATION, MAINTAINING AID VACUUM AND INCREASING THE TEMPERATURE OF SAID JACKET TO A TEMPERATURE SUFFICIENTLY HIGH TO EVAPORATE SOLVENT EFFICIENTLY MAINTAINING SAID TEMPERATURE UNTIL SAID COMPOUND BEGINS TO FOAM AND THICKEN SUBSTANTIALLY, INTRODUCING WATER AT A TEMPERATURE BELOW THE FREEZING POINT OF SAID COMPOUND INTO SAID JACKET, CONTINUING THE AGITATION UNTIL THE THICKENED MASS IS A FINE GRANULAR SOLID, AND REAPPLYING HEAT TO SAID JACKET TO COMPLETELY DRY SAID COMPOUND.

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