US2005333A - Process for refining a soap base - Google Patents

Description

June 18, 1935. J. wl BODMAN PROCESS FOR REFINING A SOAP BASE Filed June 24, 1930 2 Sheets-Sheet l June 18, 1935. J, w. BODMAN PROCESS FOR REFINING A soar BASE Filed June 24, 1930 2 Shuts-Sheet 2 a (New. A

i'vr NW Patented June. 18, 1935 U IT D STATES totem .PBQCISSI'OBWQASOAPBASI Application Jul-e24, 1m. No. 403,414

4 Claims. (CI. 87-16) The present invention relates generally to a processforrefiningasoapbase, andmorespeeifically to a process for converting a partiallydried soap base which may have a varying moisi ture content and partially crystalline structure into a homogeneous, plastic mass from which bars or cakes may be produced by conventional methods while simultaneously afiording an effective method for the uniform incorporation of perfuming, filling, and such other ingredients as may be soap. 'Ihe purpose of the invention is to provide an improved and simplified method for working a heterogeneous, partially-driedsoap base in the form of chips, spray-dried particles or granules into a homogeneous mass having the desired physical properties for extrusion, or similar or equivalent shaping operations, into bars from which cakes of soap can be molded and stamped. Arelatedpurposeistouniformlyincorporate within thesoap base during the process ofconversion other commonly used ingredients," such as perfume in the case of toilet soap anddyes or pigments where color is desired.

Still another purpose of the invention is to remove and exclude from the refined base any coarse foreign material which may inadvertently have been picked up inthe course of mechanicallyliandling the stockfrom the soapery through the dryers, and to eliminate by assimilation into I the homogeneous mass occasional small lumps of hard, over-dried soap.

Due to the severalrelated functions which it performs, the present process can be considered and generally defined as a process for refining a soap base. in which the mechanical operations of mixing, levigating, and plasticizing are simultaneously performed in a relatively'simple and efiicient manner.

The present process has particular application in the manufacture of toilet soap from dried stock, such as chips, air-dried particles or granules. Soap as it comes from the kettle following the operations of "settling" will contain approximately thirty per cent. moisture. In this form it may be drawn on into frames" where on cooling it solidifies suificiently for cutting into bars. But-for the finer. grades of toilet soap it is necessary to remove some of the water before forming into bars. This can be accomplished in a variety of ways, the most conventional of which is to fiow the molten kettle soap'over cooling rolls from which it is scraped oil. in sheets or ribbonspnto a belt moving through a drying chamber in which a r tillatedcirculation of drying air is maintained. The resultant partiallydried sheets or ribbons of soap which have, assumed a friable condition occasioned by the lossof moistureare broken up into chips by necessary or desirable in the finished further handling in mechanical conveyors. Although such a method'of drying is rapid and economical. removing thirty-five per cent. or more of the associated water from the kettle soap, it .is practically impossible to secure uniform drying throughout the mass, and in consequence a certain small but significant portion of the soap may even be dried to a point where it does not readily reabsorb moisture on standing in contact or while worked with soap of substantially higher moisture content. If particles of such over-dried soap are not re-hydrated or uniformly dispersed as particles of infinitesimal size, a bar of soap made from such unrefined stock is obiectionably gritty as it wears away in use.

In commercial practice, the levigation of partially-dried kettle soap is universally carried out by passing the partially-dried soap base through milling apparatus, consisting of a series of .rolls of progressively increasing circumferential speed and decreasing clearance between successive pairs of mils. This milling operation is also employed to combine other ingredients. such .as perfume, which is generally added to the chips or mill feed in other form to secure a preliminary rough distribution. The passage of the soap base between the bite of successive pairs'of rolls is intended to break down the larger physical aggregateaand reduce the soap to as nearly a plastic condition as possible. The

milled soap scraped from the last roll in the a series, which may comprise eight, ten or more pairs of rolls in all, is in the form .of thin ribbons quite bulky in the mass. The following mechanical operation is intended to compress the ribbons into a continuous bar of desired dimensions fromwhich inividual cakes maybe cut. The machine commonly employed for this operation is known as a plodder, and comprises a continuous screw revolving in a horizontal chamber of circular cross-section, provided on the discharge endwith a conical section from which the bar is continuously discharged.

While it is possible to manufacture an ac-- ceptable bar of toflet soap by the milling method commonly employed and briefly described above, nevertheless this method of refining has many important and characteristic disadvantages long recognized by those skilled in the art. It utterly fails to screen and exclude coarse foreign materials from the-soap base. It is inadequate to produce a quality of uniformity much desired, and lacks the control necessary to invariably produce and reproduce a refined soap having the desirable homogeneous structure. Furthermore, the milling apparatus is costlyto install, requires excessive floor space in proportion to its unit of capacity, and excessive power for its operation. Inasmuch as the physical properties of a milled soap are improved'by continued working with lessened clearance between the milling rolls, the improvement in this type of soap necessitates still further milling rolls with a greater power consumption without, however, producing a proportionate im provement in the quality of the material.

According to the present invention, the soap base is completely refined after the addition of the final ingredients in such a manner as to completely plasticize and homogenize the stock, and cause uniform distribution or dispersion of perfuming, filling, and other added ingredients throughout the mass. This is preferably accomplished by forcing the soap while maintained in a plastic condition through a series of minute orifices under comparatively high pressure. The extrusion of the soap through these orifices thoroughly extends and works the mass, and the shearing action which takes place in plastic fiow is extremely effective in producing a product having the desired physical properties. This is apparently due to the fact that the mechanical working of the soap is attributable to the linear fiow of the stock forced under pressure through the orifices, with concentric layers flowing at different relative speeds with attendant shearing and milling action. For the purpose of promoting the most economical operation, it is preferable to initially force or extrude the soap stock through orifices larger than the final orifices, and thereafter as the fiuidity of the soap stock increases from stage to stage to progressively decrease the orifices until the final size of orifice is reached. For the further promotion of greatest efficiency, it is desirable to thermostatically control the temperature conditioning of the soap during the refining process, or in other words to insure that the soap shall be maintained during its extrusion through the minute orifices at a temperature best adapted to maintain the desired flow conditions. This temperature should neither be so high as to cause too great fiuidity of the soap nor so low as to cause the soap to harden and interfere with its proper handling during the process of refining.

It has been found that the efficiency of the operation can best be maintained through the provision of orifices, such as those furnished by a fine mesh screen surface. To maintain the screen against the considerable pressure engendered by the forcing of the soap base therethrough, it is desirable to back the screen with a support designed to permit the passage of the extruded soap freely therethrough. The refining action secured by the employment of minute orifices of inconsiderable depth is much superior to the action produced by forcing the soap through orificial passages of considerable depth, as in the case of a perforated plate of sufilcient thickness to withstand the pressures engendered in forcing the soap therethrough. It is proposed to deliver the soap stock to the orificial surfaces, as screens, by screws operating in closed barrels, which are designed to primarily compact and bring the mass as a whole to an optimum temperature controlled through the employment of a surrounding jacket which in the present case may have water circulating therein to control the upper limit of temperature and avoid undue elevation in temperature of the soap. To promote the volumetric efficiency of the orificial surfaces and aid in reducing hard particles by attrition, one or more revolving blades may be mounted on the screw shaft and serve by rotating in proximity to the orificial surface to aid in working the plastic mass of soap thercthrough, further reducing by attrition hard particles of dried soap which may be present into such a condition that these particles are completely assimilated by the mass. Not only does the homogenizing of the soap coupled with the prior conditioning effectually refine the plastic material, especially when repeated through orifices of diminishing size, but the extrusion or forcing of the soap through the minute orifices serves a screening function to preclude conveyance into the finished soap of such foreign materials as may inadvertently be collected and which cannot be reduced by the condition ing of the material.

An important and desirable aspect of the process is the maintenance of the soap base during the refining thereof at a predetermined consistency through the maintenance of temperature between generally predetermined limits. By properly controlling the consistency through maintenance of temperature in this manner, the desired refining results may be secured, whereas without such maintenance of proper temperature conditions, attempts to thus refine the soap are ineffective. It follows, therefore, that the development of the refining operation in a closed system with the maintenance of predetermined temperature limits is an important and essential adjunct of the process.

According to the best method of practising the invention now known, the plasticized soap is forced through and extruded from wire screens which progressively diminish in size of mesh. Goods results have been obtained by graduating the mesh from an initial screening area of twenty mesh downwardly to forty mesh, with possibly one intermediate screen therebetween. In conjunction with the wire screening devices, it has been found desirable, as stated heretofore, to provide perforated supports to resist the pres-t sure on the screens, but provided however with relatively large openings, the aggregate area of which substantially exceeds that of the screen openings, thus avoiding any restriction from the passage of the homogenized soap therethrough.

In the accompanying drawings illustrating the preferred form of the invention,

Fig. 1 represents an elevation partly in section of a suitable apparatus for carrying out my process; and

Fig. 2 is a section illustrating the screen and correlated devices on an enlarged scale.

As carried out in this apparatus, a kettle soap dried to a moisture content of five to twenty per cent. approximately, and to which has already been added perfuming, filling, and such other ingredients as are desirable, is delivered to a hopper l communicating with the interior of a closed chamber or barrel l2 in which is mounted a revolving feed screw I 4. This feed screw conveys the soap lengthwise of the barrel, and preliminarily plasticizes and mixes it during its travel. At the delivery end of the feed screw is located the initial screen l6 of twenty mesh approximately, supported by a plate I8. Operating in conjunction with the screen and in proximity thereto are a series of rotating blades 20 mounted upon the shaft 2| of the feed screw,

and aiding to force the plasticized stock through the screening device. The blades effectively augment the function of the feed screw by virtue of the attritive effect exerted upon the soap, tending to reduce hard particles of soap to dimensions of sufficient size to permit their ready passage through the screen. The feeding device coupled with the resistance at the surface of the screen creates a substantial pressure generally in excess of 250 pounds per square inch which is instrumental in creating the desired action upon the soap. From the first or initial screen of twenty mesh, the partially refined soap is discharged through the duct 24 to a second or intermediate feed screw 26 which delivers the soap to a second or intermediate screen 28 of thirty mesh, this screen being supported by a perforated member 30 and cooperating with attritive blades 32 in a manner similar to that previously described. From this second or intermediate screen, the soap is again discharged through a. duct 36 to a feed screw 38 which conveys it to a third and final screen iii of forty mesh, having a perforated support 42 and cooperating with blades Obviously the number and character of screening devices may well be altered as occasion requires without affecting the broad concept of my invention. Furthermore, the size of the screens may be altered as the condition of the base may necessitate. The soap base in process of refining is maintained within desired temperature limits through the employment of a surrounding jacket adapted to contain temperature regulating fluid, such as steam or water, depending upon whether the function is to remove the heat from the mass of soap or prevent escape of heat therefrom. This jacket, as indicated generally at 50, surrounds each of the plasticizing chambers or barrels. If extreme accuracy is desired, the requisite temperatures within the refining apparatus may be maintained by any desired method of temperature control (not shown), or in the absence of such method of temperature control, approximate temperature limits can be maintained satisfactorily by manual control of the volume and temperature of the fluid passing through the jackets. The optimum temperature at which the base should be worked cannot be specified precisely and is governed by the characteristics of the particular soap stock in process of refining. Generally speaking, the condition of the soap should be such as to maintain a substantial working pressure at the orificial surfaces.

A specific example of the improved method of refining may be cited in connection with a kettle soap having the following composition:

Per cent Palm oil 50 Tallow 25 Cocoanut oil 25 The soap coming from the kettle contains approximately thirty per cent. of moisture, and is partially dried in chip form to a twelve per cent. moisture content approximately. These partially dried chips are delivered to the first stage of the refining operation at a temperature slightly above F. This temperature may rise slightly throughout the three stages of the operation, approximately 10 to 20 higher at the completion of the refining operation. It will be understood that the entering temperature is determined by practical operating conditions, and might desirably be somewhat lower than that indicated without in any way altering and in fact in some cases improving the efiiciency of the operation.

As will be evident to those skilled in the art in view of the foregoing specification, my improved process as carried out in the above-described apparatus accomplishes several distinct and advantageous results. nlpulation of the soap on passage through the screening devices, especially when complemented by the attrition of the stock in proximity to the screening devices, thoroughly homogenizes all of the soap subjected to the refining operation, repeatedly extruding it in condition particularly favorable for compression into a smooth bar. The hard particles of soap are progressively reduced by attrition, and the accompanying hydration until. they are completely absorbed in the soap as a whole. Aside from the major and important function of thoroughly working and homogenizing the soap, the screens serve the further and useful purpose of impeding or preventing the passage of foreign material which may inadvertently collect in the soap and which is of such a character that it cannot be reduced and caused to pass therethrough. Obviously this foreign material collects ahead of the screens, is removed from the soap passing therethrough, and can be completely removed from the refining apparatus by removal and cleaning of the screens.

What is claimed is:

1. That step in the process of homogenizing and refining a soap base for the production of a homogeneous plastic mass from which bars or cakes may be subsequently formed, which consists in regulating the temperature of the base to maintain a predetermined condition of plasticity and, while so maintained, forcing the base under high pressure through minute orifices of a size comparable to or less than the orifices of a 20-mesh screen.

2. The process of homogenizing and refining a soap base for the production of a homogeneous plastic mass from which bars or cakes may be subsequently formed, which consists in regulating the temperature of the base to maintain a predetermined condition of plasticity and, while so maintained, repeatedly forcing the base under a high pressure through successive sets of minute orifices of decreasing size, with none of the orifices having a. size comparably greater than the openings of a 20-mesh screen.

3. In the process of homogenizing and refining a soap base for the production of a homogeneous plastic mass from which bars or cakes may be subsequently formed, the steps which consist in regulating the temperature of the base to maintain a predetermined condition of plasticity and, while so maintained, forcing the base under high pressure through minute orifices of a size comparable to or less than the openings of a 20-mesh screen and supplementing the forcing by pressure through the orifices by a rubbing and attritive action.

4. That step in the process of homogenizing and refining a soap base having a moisture content not in excess of 25% approximately for the production of a homogeneous plastic mass from which bars or cakes may be subsequently formed, which consists in regulating the temperature of the base to maintain a predetermined condition of plasticity and, while so maintained, forcing the base under high pressure through minute orifices of a size comparable to or less than that of the openings in a 20-mesh screen.

JOHN W. BODMAN.

The working or ma-

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