US2188944A

US2188944A - Tableted polychlorophenol salts

Info

Publication number: US2188944A
Application number: US168202A
Authority: US
Inventors: Kent R Fox; Hatfield Ira
Original assignee: Monsanto Chemicals Ltd
Current assignee: Monsanto Chemicals Ltd; Monsanto Chemical Co
Priority date: 1937-10-09
Filing date: 1937-10-09
Publication date: 1940-02-06
Anticipated expiration: 1957-02-06

Description

' pound sets to a mass resembling'pl'aster of Paris Patented Feb. 6, 1940 TABLETED' POLYCHLOROPHENOL SALTS Kent R. For,v St. Louis, and Ira Hatfield, Webster Groves, Mo-., assignorstc:-Monsanto..Chemical Company, St. Delaware v No Drawing.

Louis, M0., a corporation of Application October 9, 1937, Serial No. 168,202

6 cl ims. (01. 23-245) {The present invention relates to watersoluble polychlorophenol salts, particularly pentachlorophenol salts, and refers to a new and improved physical 'form oi'such 'salts'which permits of their more advantageous handling in commerce and in industry 'Without substantial impairment of their ease of solubility.

I Pentachlorophenol and tetrachlorophenol salts in the dry powdered condition or in'the form of "theirmonohydrates, particularly the sodium salts ofthese phenols, are very light in bulk and are easiiy'blown'about; In handling such materials it is-difiicult to avoid dusting. These salts produce local irritation of the skin and mucousn embranes of the nose and throat and on continued exp'osur fmay produce a dermatosis of the skin characterized either by redness or anacneform eruption. The salts even when-inhaled in small amounts produce sneezing followed by excessive rhinorrheathat is, excessivedischarge of mucous from the nostrils. hazardous and have been-avoided because of the special precautionsrequired in their use.

Sodium pentachlorophenate or the monohy-. drate in the dry powdered condition readily dis-' solves in water by stirring. However, when itis merely .wetted with sufficient water, hydrate formation occurs-and the resulting hydrated-com- -Which is far more difficult to dissolve. Although the hydrated salt is less hazardous to handle, it is surprisingly more difiic'ult to use because of its failure to dissolve rapidly. Furthermore, dry sodium 'pentachlorophenate' which has been exposed to the atmosphere Will over a period of time develop varying proportions of water-insoluble components. a loss to the consumer. The primarycbject of the present invention is to produce Water-soluble salts of polychlorof phenols in a-form such that they are readily and completely soluble in water, are non-dusting, are not appreciably affected by exposure to the atmosphere, and. which-dissolve quickly and completely even after storage.

We have found that-the above objects are attainedin an especiallyadvantageous manner by producinglthe polychlorophenol salts in the 'form of .tablets or briquettes in the manner described hereinafter. l

difificulty in attaining the objects of the present inventionhas been encountered in making acompacted mass which While in vcompactform should-not be fragile and aiiected by atmospheric moisture and which, on the other hand, should.

Such materials, therefore, i are 9 The insoluble material represents when droppedintowater dissolve rapidly therein. Excellent tablets or briquettes can by produced by simple moistening of sodium pentachlorophenate with water and molding, but the resulting tablets resemble set plaster of Paris, are diflicultly soluble, and are therefore entirely unsatisfactory. Anhydrous "sodium pentachlorophenate itself can be compressed into a tablet or briquette but the mass'crumbles on standing. Any binding agents containing water which are added to aid in tableting or briquetting, for example, sodium silicate I solutions, produce hydration of the salt, Whereas bituminous, tarry or similar binding agents are not usable because they, of themselves, being in- 115 soluble, make the resulting tablet-or briquette extremely difficult to dissolve. Furthermore, When sodium silicate is used-as a'bindin'g agent for the tablets "or briquettes, it 'pro'duces'a powder which adheres to the -metal equipment and the resulting tablets are not readily disengaged from the mold after compression.

On the other hand, when starch is added to the material as a bind- 'ing agent it yieldsa tablet of more or less -lamellarform, as a result of which it crumbles and-disin'tegrates readily. The application of the common methods heretofore known, failed to produce coherent masses of required solubility in Water. v H

The present invention is based upon our unexpected discovery thatsodium tetrachlorophenates and 'pentachlorophenate of controlled moisture" content -will form into coherent tablets or briquettes whencompressed in a particular manner, hereinafter described in full, to produce the desired'objectsset forth above. In such tablets or briquettes the outer surfaces are in more or less coherent form whereas the interior 'is-"in par- 7 ticulate 0r granular formQ The tablet is impervious :to atmospheric moisture and air to a remarkable degree and the salt in the interior of the tablet or briquette is thereby protected from decomposition and dehydration.

The tablets, briquettes or cakes are substantially noncrumbling, "non-hydroscopic and quescenuthat is, they neither absorb nor liberate waterto any appreciable extent. The small content of moisture required .for producing such co- 'herent tablets or briquettes is without substantial effect on thesolub-ility in water of the formed 50 mass. When. the salt is thus used in the form of coherent tablets there is little danger of the occurrence or dusting. Elven should any. small particles become disengagediroin a formed cake non delior tablet by abrasion ordroppingthey are in a compressed or agglomerated form and not in the form of a fine bulky powder that is a hazard.

In an example of the method of practicing the invention a powdered sodium pentachlorophenate containing from approximately 3% to 10% of moisture or water is used. Such moisture or water is probably held in the salt as water of crystallization, inasmuch as the salt itself is sub-' stantially dry. This water content may be controlled in the production of thesalt or water may be incorporated into dried sodium pentachlorophenate powder of a lower moisture content by careful uniform mixing in the customary manner, care being taken to avoid any local concentration of water which would result in hydration to the less soluble form. By controlling the drying operation used in the productionof the salt this moisture content can be maintained most conveniently. This optimum moisture content isvarlable to some extent, the limits beingapproximately 3% to about which corresponds to from roughly A; to 4 molecules of water for each molecule of anhydrous sodium than 70% or thereabouts of water are fluid susv pensions or solutions, for example, parts of v tion are intended particularly for ,thepreparapentachlorophenate. At about a water content of the product produces a hydrate which sets similar to plaster of Paris. With proportions of water from about 30% to as high as 70%, the products are solids. Products having more dry sodium pentachlorophenate in about '75 parts of water yields a clear solution at room ternperature. For best results in tableting or briquetting, a water content of about 3% to 10% is most satisfactory. Smaller water contents require greater pressure in the tableting operation and yield tablets which disintegrate too readily.

Products of higher water content (containing quetted in the followingmanner: The powder is efed to a tableting machine of conventional design in which the pressure applied to the mold is from approximately 5,000 to 20,000 pounds per from about 10% to 20% water) do not compress with any substantially greater ease than those of about 10% water content, and since these products have a higher water content, the sodium pentachlorophenate becomes more expensive to ship and the tablets or briquettes themselves have a smaller margin of safety with regard to any detrimental effects which might result from any extraordinary exposure to moistureor accidental wetting.

The powdered sodium pentachlorophenate of controlled moisture content is tableted or brisquare inch. .The resulting molded mass, which at this stage is easily broken when dropped, is then disintegrated or granulated in a cob mill or a suitable grinding machine to yield particles of about 1 to 10 mesh in size, the preferred size being approximately 4 mesh. The particulate compressed material or granulations are then subjected to a second compression under approximately the same conditions in a mold.

The mold in this first compression can be of any shape or size but the mold used in the final compression (recompression) should be that corresponding to the form in which the final tablets are desired. After this second compression the resulting tablet is firmly coherent and will easily resist abrasion or breaking during handling and transportation. The recompressed tablet is not deliquescent or efiiorescent and is substantially impervious to atmospheric moisture or carbon dioxide. On standing exposed to the atmosphere for long periods there is no substantial disintegration of formation of water -insoluble com pounds. To prepare'aqueous solutions of the salts from the tablets, agitation is desirable, preferably agitation by means of aujet of steam through the solution.

- Instead of using one preliminary compression f and granulation as above, the salts'may with advantage be subjected to two or more preliminary compressions to produce compacted particulate masses or granulations. The preliminary and final compressions may be conducted if desired on suitable rotary briquetting machines, al-

though in this event more than two compressionsand granulations are usually necessary since such briquetting machines permit the application of great pressures but do not in any one compression reduce the bulk of thern'aterial sufficiently.

The pressures which areapplied to the mold v in the tableting operation are'somewhat variable,

but are within a preferred range of from about 5,000 to 20,000 pounds per square inch. Less pressure may be used in the preliminary molding as can be well understood. The pressures to betion of baths for the treatment of wood toprevent the growth of sap-staining organisms and other fungous growths. Insuch use a precipitation of the polychlorophenol appears in the bath after prolonged Wood treatment; This precipitation in such baths can be prevented and the quality of the tablet or briquette is furthermore markedly improved by the incorporation with the salt of a small proportion of sodium hydroxide v or potassium hydroxide or other suitable strong alkali. Proportions of from 1% to 1 0% of sodium hydroxide have an especially advantageous ef feet on the quality of the resulting tablet and.

aqueous baths made with such sodium-hydrox+ ide-containing tablets can be used for long .periods without any difiiculties from precipitation of the free chlorophenols. The sodium hydroxide can be advantageously incorporated inthe original preparation of the salt, that is, prior to the I drying of the salt. I Tablets containing alkali in these proportions, surprisingly, are not affected to, any substantial extent by prolonged exposure to the atmosphere, any more than tablets not containing alkali.

,To aid in solubilizing the tablet or it is desirable also to add asmall proportionof a Wetting agent such as a sulfonated high molecular weight alcohol or preferably asulfonated alkylated aromatic hydrocarbon such as briquette I that known to the industry under the trade name Santomerse. For this purpose less than 1% by weight of Santomerse is'ample. I

Additions of coloring agents, substances which 7 exert a synergistic action upon the polychlorophenol; talc or other mold lubricants, and similar components of a secondary nature in small 1 proportions may be made prior to the compression without necessitating changes in the mold.-

ing procedure. I

The invention is particularly applicable to the tableting or 'briquetting of sodium tetrachloro- The optimum understood that mixtures of sodium tetrachlorophenates and sodiumpentachlorophenate are also influenced to some extent by the factors pointed out hereinabove but will be within the range of 3% to 20% which has been. specified for sodium pentachlorophenate.

Inasmuch as this specification contemplated. What we claim is: i

1. A formed compressed coherent mass consisting predominantly of sodium pentachlorophenate having a moisture content of from 3% to 20% and containing from 1% to 10% of sodiumhydroxide, and being characterized by being readily and substantially completely soluble in Water, said product beingobtainedby compression of the powdered salt, subsequent granulation of the compacted mass, and final molding thereof.

2. A formed compressed coherent mass consist ing predominantly of va sodium salt selected from the group consisting of the sodium salts of tetrachlorophenol and pentachlorophenol having a moisture content of from approximately 3% to 20% and containing from 1% to 10% of sodium hydroxide, said tablet being characterized by being readily and substantially completely soluble in water.

comprises pre-v ferred embodiments of the invention it is to be understood that it is not limited to these specific 3. A formed compressed coherent mass consisting predominantly of sodium pentachlorophenate having a moisture content of from approximately 3% to 20% and being readily and substantially completely soluble in water.

4. A recompressed tablet consisting predominantly of a sodium salt selected from the-group consisting of the sodium salts of tetrachlorophenol and pentachlorophenol having a moisture content of fromapproximately 3% to 20% and containing from 1% to10% of sodium hydroxide,

said tablet being readily and substantially completely soluble in water.

5. A recompressed tablet consisting predominantly of a sodium pentachlorophenatehaving a" moisture content of from approximately 3% to 20% and containing from approximately 1% to 10% of sodium hydroxide, said tablet being characterized by its resistance to breakage and abrasion and by being readily and substantially completely soluble in water.

6; The method of tableting a salt selected from the group consisting of the sodium salts of tetrachlorophenol and pentachlorophenol, consisting in incorporating uniformly with said salt a proportion of water such that the water content of the salt corresponds toifrom 3% to 20% of the mass I and a proportion of sodium hydroxide such that themass contains from 1% to 10% thereof, and

c: thereafter by means of compression and disintegration producing a mass of said salt of reduced bulk in particulate granular form, and subse-' quently subjecting said granulated mass to a final molding to produce a coherent tablet which is readily and substantially completely dissolved in water.

KENT R. FOX. IRA HATFIELD.