US 2560097 A
Description (OCR text may contain errors)
Patented July 10, 1951 I UNlTElDYSTATES PATENT Y I 2,560,615?
HAND CLEANING TABLET Cherry L. Emerson, Jr., Newton Highlands, and William R. Cuming, Boston, Mass., vassignors to Lawrie L. Witter, as trustee No Drawing. Application January 25, 1949, Serial No. 72,756
, 2 Claims. (01. 252 -89) efiective in cleaning the hands through attrition and emulsification, Will have sufficient strength including small pellets or bars of soap, have been heretofore known but these have not been satisfactory products. Further, we are aware that tablets, primarily in the pharmaceutical field,
have been adapted to disintegrate rapidly in:
water, but the techniques used are not feasible in producing a rapidly disintegrable hand cleaning tablet.
Small bars or pellets of soap or non-soap detergents are not satisfactory for individual use because in the normal manufacturing process the product is so dense that the surface exposed to water for effecting solution of the detergent is small, necessitating prolonged rubbing by the user. Penetration of water intothe interior of the bar is negligible. During the rubbing the bar is likely to slip from the hands of the user and become lost; moreover, the central portion of the bar is wasted should the user be able to extract suflicient detergent for his hand cleaning requirements. To decrease the density of the bar to the point where rapid disintegration in use occurs is impractical as the product then becomes too fragile prior to use.
In tableting pharmaceutical products the technique used for effecting rapid disintegration consists of compressing in a mold a granulation to which has been added a small quantity (3 to 5% by weight) of dry starch or similar substance. Upon contact with water the starch swells, breaking apart the tablet granules. Effervescence is also occasionally employed, the escaping gas serving the disintegrating function. To maintain the integrity of pharmaceutical tablets when in the .possible for reasons which will presently become clear. 7
In fabricating a rapidly disintegrating hand cleaning tablet the techniques employed in the tableting art are not applicable. The detergents which we have found suitable with regard to their cleaning and emulsifying properties are of a plastic nature, that is, they undergo considerable plastic flow when subjected to the pressures normally used byus in the process of our invention.
Moisture content increases the degree of plastic flow during compression. We normally use a granulation which contains approximately 2% moisture. Typical satisfactory detergents used by us are alkyl aryl sodium sulphonates, and cocoanut oil soap.
To produce an efiective hand cleaning tablet it is necessary that a significant portion of the composition be a detergent which as previously indicated is of a plastic (fiowable under pressure) nature. To produce a hand cleaningtablet in which the active detergent ingredient is less than approximately 10% of the tablet weight, the remainder being a pressure non-flowable and water insoluble filler, is feasible by utilizing established pharmaceutical tableting methods as previously outlined. Such a tablet however is impractical since the active ingredient is diluted to such a degree that the tablet is cumbersome and ineffective We have invented a new and improved one-use hand cleaning tablet and the method of making same in which the proportions of active detergent may be as high as of the weight of the tablet while still maintaining the desirable properties of dry integrity and rapid disintegration in use. The actual percentage of detergent which we use depends primarily upon its activity as a cleaning agent. In general, the non-soap detergents are used in smaller proportions than soap. We have used soap and non-soap detergents together in several formulations; In preparing a granulation for tableting, we may either mix together the tablet ingredients in the dry state or in the presence of water. In the latter case the material must be dried prior to tableting.
The following is a preferred composition. The ingredients as listed will produce approximately grams of dry composition:
25 grams sawdust 25 grams alkyl aryl sodium sulphonate 50 grams sodium sulfate 0.8 cc. 1% methylene blue solution 1.0 cc. ortho cresol in a mixture of 5 cc. ethyl alcohol and 5 cc. water The alkyl aryl sodium sulphonate and the sodium sulfate are dissolved in 250 cc. of water and the solution is brought to a boil. The methylene When the solution is clear blue is then added. the sawdust is added and boiling is continued to drive oii a part of the water and leave the material in the form of a thick slurry. This is placed dome faced plungers.
3 V in a helby m drying p enma t nc a a temperature of 110 C. The material is stirred from time to time to prevent caking and the formation of a detergent film on the surface. When the material is dry it is wetted with the ortho oresol solution and again dried- The material is then broken up, and passed Qtlirough a 10 mesh per inch sieve. The moisture "cd ntefit of the material is brought to approximately 2% by spraying with water and mixing thoroughly. The granulation is then ready for tabletin'g.
Approximately 1.3 grams of material is introduced to a die which is in diameter with V The granulation is compressed to 6,500 pounds per square inch. The resulting tablets have a void volume to solid constituent volume ratio of roughly 0.5. These tablets have excellent dry strength, disintegrate readily in use and are extremely effective as hand cleaning agents. 7
We have used a variety of detergents as the active ingredient in the hand cleaning tablet of our invention. Specifically, the following detergents have been used and are illustrative:
The alkali salts'of palmitio, stearic, oleic and linoleic acid. These soaps are present in the wool soap manufactured by Swift & Co.
ponol M E Dry.
An alkyl arylsodium sulphonate manufactured by Monsanto Chemical Co. and sold as Santomerse D.
An alkyl sodium'sulphonate manufactured by Dupont and sold as M P I89. Sodium sulfate is incorporated in this product as a diluent. V
A sulphonated glyceride ester manufactured by Colgate Palmolive Peet C0. and sold as Arctic Syntex M. V
A protein'derived detergent manufactured by Kalide Corp. and sold as Lamepon 4C.
Obviously other detergents, for example sulfated or sulfonated amides, sulfated or sulforated amines and quaternary ammonium compounds maybe incorporated in the hand cleaning tablet of our invention to achieve desired characteristics.
coalesces into a homogeneous mass when sub'- jected to a pressure of 6,000 pounds per'square inch and as non-pressure flowable a material which does not coalesce into or resemble a homogeneous mass when subjected to a pressure of 12,000 pounds per square inch.
As fillers we have used organic and inorganic materials and combinations thereof.
The organic materials used include maple wood sawdust, pine wood sawdust, wood flour,
arrowroot starch, corn meal, wheat hulls, ground leather, comminuted paper, cane sugar and sorbitol. Inorganic materialsv include silica gel, alumina gel, sand, pumice, kieselguhr, sodium carbonate, sodium sulfate and trisodium pliosphate. for imparting specific features to the final prod- Obviously, other materials may be used uct. For example, sodium silicate may be used as a water softening agent.
We prefer to use as a filler a porous hydrophilic solid with a water permeable structure of the ultimate particle. Among the organic fillers, those high in cellulose and/or starch content have particular merit. We have found the following to be highly satisfactory: wood sawdust, weed flour, cornmeal, silica gel and alumina gel. Sodium sulfate is a preferred non-porous filler when using sulfated or sulphonated detergents as it is often incorporated as a diluent in commercially available products.
The particle size distribution of the filler is selected in accordancewiththe degree of attrition desired in the final product. We have found that wood sawdustof screen analysis through 40 and on 48 mesh per inch is satisfactory when mild scrubbing is desired. If gentle action is desired a more finely divided filler is used.
We have discovered the tablet structural conditions which must be fulfilled in order to produce'satisfactory hand cleaning tablets in'which the percentage of detergent constituent i's'high. We have also discovered the mathematical expression which relates the percentage plastic constituent in the granulation to the maximum permissible pressure to which the granulation may be subjected in the tableting operation. Higher pressures than those given by'tlie expression will produce tablets which "are ii'iisatisfactory as regards wet disintegration in use.
The expression is:
Pmax=35,0006" where- Pmm=the maximum permissible compression pressure in pounds per squareinch'to produce a satisfactory hand cleaning tablet.
D=the fraction by weight of plastic constituent in the tablet. The plastic constituent is normally a detergent. h
e is the base of the natural logarithms and has the value 2.72.
I We prefer to produce tablets ,in. whichthe amount of detergent is roughly 0.35'of the tablet weight. We find. that the expression helds lexceedingly well over the range of plastic constituent fractions from 0.125 to 0.75. Tablets containing less than 0.125 detergent are ineffective hand cleaners, while those containing morethan 0.75 detergent have the undesirable"characteristics of a solid bar or pellet. v
In developing the mathematical expressio'n'referred to a large number of "tablets were produced from granulations coh'tainingjvarious percentages of plastic constituent. The granulations were preparedby'eitlier mixing together the ingredients in finelydivided dry form or by preparing a water slurry of the "constituents,
graph paper. Compression pressures which are greater than those given by the equation yield tablets which do not disintegrate readily. The
equation holds over the range from 0.125 to 0.75
detergent. Below 0.125 plasticconstituent tablets of a hand cleaning tablet which must be realized so that the tablet will have the desirable properties of dry strength and rapid wet disintegration. We have discovered that the voids within the tablet must bear a definite relationship to the volume. occupied by solid constituents. We have discovered that the void volume to solid constituent volume ratio cannot be below 0.12 nor greater than 1.8. We prefer to use in our tablets a ratio of roughly 0.5. By void volume we mean that volume of a tablet prior to use not occupied by a solid or liquid constituent. Normally the voids are filled with air which is quickly displaced by water and causes rapid disintegration when the tablet is used.
Experimental data was obtained by preparing a number of granulations and tablets therefrom. The tablets were compressed at various pressures. Flat faced plungers were used in the die. The dimensions of each tablet were measured; and each tablet was weighed. The total volume of the tablet was obtained by calculation. Tablets for each pressure used were subjected to dry strength tests and.wet disintegration tests in use. In these two respects tablets were rated as excellent, good, poor and unsatisfactory. It is to be noted that a tablet rated as unsatisfactory in either respect is not suitable as a hand cleaning tablet. Tablets designated at unsatisfactory as regards wet disintegration were, in general, produced at pressures higher than those given by the previously referred to mathematical expression, whereas those rated excellent, good and poor were produced at pressures below that given by the expression.
The determination of voids was accomplished in the following manner. Dependent upon the materials used in a specific tablet composition, a low viscosity liquid was selected in which all constituents were sparingly soluble. For example, it was determined that tablets containing only maple sawdust and Santomerse D, an
alkyl aryl sodium sulfonate detergent manufactured by Monsanto Chemical Co., were sparingly soluble in acetone. Prior to use the selected liquid was saturated with the constituents of the tablet. This was accomplished by allowing a large quantity of the constituents to stand in the liquid for several days with occasional stirring. Tablets of each granulation and of each pressure used were then immersed in the selected saturated liquid as prepared above. The liquid was contained in a graduated cylinder. The change in the liquid level in the cylinder then was interpreted as the solid constituent volume of the tablets. In the case of 'very dense tablets several hours were allowed for penetration of the This accounts for the low percent-;
1 Example 1 Composition 1 part (by weight) -alkyl. aryl sodium sulphonate 2 parts-sodium sulfate 1 part- -pine sawdust The granulation was prepared essentially in accord with the previously outlined procedure. The particle size distribution in the granulation was through 10 and on 60 mesh.
Dry Strength Wet Disintegration Ratio Excellent Excellen DoIIIIIIT'""'" 'IIIII Unsatisfactory I: Poor Excellent--. Unsatisfactory do Example 2 Composition:
2 partsalkyl aryl sodium sulphonate 4 partssodium sulphate 3 parts-calcium carbonate The granulation was prepared in accord with the outlined procedure. The particle size distribution was through 10 mesh (0.065 screen opening) and on60 mesh."
Dry Strength Wet Disintegration Ratio Excellent Good o. 433 Do Unsatisfactory. 0.118 Poor- Excellen 0. 748 Unsatisfactory. do 1. 87
Example 3 Composition:
2 parts-alkyl aryl sodium sulphonate 4 parts-sodium sulfate 3 parts-silica gel The granulation was prepared in accord with the outlined procedure. The particles in the granulation passed through a 10 mesh sieve.
Dry Strength Wet Disintegration Ratio Good 0.550 Poor 0.204
Example 4 The granulation was prepared in accord with the outlined procedure. The particles in the granulation passed through 10 mesh screening.
Dry Strength Wet Disintegration Ratio Excellent Excellent l. 0. 657
Having-thus disclosed our inventionfand described in detailcillustrativeembodimentst'themof; we. claim as new and desiretov secure by Letters Patent:
1; A'dry'one-use cleaning tablet having adny strength sufficient to sustain it, against breakage in transit and storage, and a void content. sufficient to cause it readily to absorb. water and rapidly disintegrate in the presence of: moisture, consisting essentially of a solid ionic. organic detergent and a substantially water insoluble solids filler mixed together and compressed at a pressure of about that given by the expression R=3;5;0o0er in which D is-the weightv fraction of detergent in the tablet and e ish-thebase-of the 15 natural logarithms and has the valueof- 2.72, the detergent being not,1ess'than0.125 and not greater than 0.75 of the tablet Weight and the 'tablet having a gas void volume to solid volume in a ratio o f' notless than 0.24 and-snotgreater I 20 in whichthe weight ,1 of the detergent-is-bet-ween .25: and: .5 0 of the weight of. the tablet and the filler comprises a granular cellulose.
CHERRY L. EMERSON, JR; WILLIAM R. CUMING;
REFERENCES CITED The following references are of record in the m file of..tl1is patent:
UNITED STATES. PATENTS Number Name Date 2175,28'5v Duncan Oct. 10, 1939 2.401647" Bodman Sept; 1'7, 1946 2322 128 Percy June. 10, 1947 FOREIGN PATENTS Number Name Date" 5,698 Great Britain 1881 OTI-IEI-K. REFERENCES Publication: U; S. Dept. of Commerce, National Bureauof Standards Circular C424--Washing, Cleaning I and' Polishing 'Materials, p. a 17.