US3481880A - Detergent laundry bars - Google Patents

Description

Dec. 2, 1969 A. E. AUSTIN ET AL 3,481,880

DETERGENT LAUNDRY BARS Original Filed Feb. 21 1966 2 Sheets-Sheet 1 Q 5 6 Q 26 n INVENTOR.

AMQRY EARL Ausrm CHARLES FREDERICK F\$C\-\ER I W W/W4 70 E) Dec. 2, 1969 E. AUSTIN ET AL 3,481,880

DETERGENT LAUNDRY BARS Original Filed Feb. 21 1966 2 Sheets-Sheet 2 INVENTOR.

AM 0 RY EARL AUST t N CHARLES FRI-022K F SCHE-Q United States Patent C) 3,481,880 DETERGENT LAUNDRY BARS Amory Earl Austin, Colonia, and Charles Frederick Fischer, Jersey City, N..l., assignors to Colgate-Palmolive Company, New York, N.Y., a corporation of Delaware Continuation of application Ser. No. 529,087, Feb. 21, 1966. This application Nov. 12, 1968, Ser. No. 796,253 Int. Cl. Clld 1/02 U.S. Cl. 252-138 11 Claims ABSTRACT OF THE DISCLOSURE A process for making low density built detergent laundry bars in which a plastic blend of synthetic anionic detergent, water-soluble, hydratable builder salt and water is passed continuously through a zone of intense shear in the presence of gas and the gasified mass is continuously extruded as a bar. Hydration of the hydratable builder salt occurring after extrusion, and contributing to, the hardening to the gasified bar.

This application is a continuation of our copending application Ser. No. 529,087, filed on Feb. 21, 1966.

The present invention relates to a process and apparatus adapted for the continuous manufacture of a laundry bar comprising an anionic synthetic detergent and water-soluble inorganic builder salts and to the resulting products, as hereinafter described.

Within the last decade, commercial interest has developed in a laundry bar containing a minor amount of synthetic detergent and a substantial proportion of inorganic salts, particularly due to the commercial success and substantial consumer acceptance from about 1957 of a detergent bar product known in the detergent field under the name of Limpiol. This product was a mechanically worked, plodded detergent bar which contained usually according to analysis about 25-30% sodium higher alkyl benzene sulfonate detergent, about 60-65% inorganic salts and about ll2% water. The inorganic salt in the product was about 35-40% sodium bicarbonate and about 18-20% sodium tripolyphosphate primarily. It is understood that this product was made by a batch method which usually involved (1) mixing liquid alkyl benzene sulfonic acid and water with the inorganic salts in powdered form in a standard heavy-duty mixer to form a uniform mixture whereby powdered carbonate and bicarbonate dry neutralized the sulfonic acid to form the sodium salt with the release of carbon dioxide and Water,

(2) the mixing was continued until complete neutralization was obtained from the practical'standpoint and, (3) the resulting solid mixture was then fed to a soap plodder which further mechanically worked and compressed the mixture, and then extruded it in the form of a continuous bar which was cut into cakes or bars for individual use. It was known also to commercially manufacture laundry bars by equipment consisting of a tilting amalgamator for mixing organic detergent salt and inorganic salts, a mill for further fine mixing as desired, and plodders to form an extruded bar, such as US. Patent 2,845,391. Other methods are described in US. Patent 2,205,037 and 2,941,948 for example. Subsequently, similar processes have been proposed such as described in US. Patent 3,178,370 wherein a fine spray of sulfonic acid is sprayed onto an agitated bed of inorganic salts including carbonate to effect partial neutralization of the sulfonic acid with the release of carbon dioxide, and thereafter the mixture is further mechanically worked to make it more homogeneous and to complete the neutralization.

The detergent laundry bars produced in accordance with all these processes have, because of their high con- 3,481,880 Patented Dec. 2, 1 969 tent of builder salts, been quite dense, typicall having a density of about 1.57 as compared with the density of a typical laundry soap bar of about one. Detergent laundry bars of the same weight as the ordinary laundry soap bars have been, therefore, of considerably smaller size, presenting a correspondingly smaller surface area for washing purposes.

In accordance with one aspect of our invention, we have developed a process for making detergent laundry bars of substantially lower density, despite the fact that the bars contain a large amount of builder salt, well in excess of the amount of synthetic anionic detergent. A mixture of the detergent, said excess inorganic salt and Water are passed, in plastic state, continuously through a zone of intense shear in the presence of gas to disperse the gas throughout the plastic mixture passing through said zone. Preferably the mixture is formed by feeding the finely divided builder salt continuously to a zone in which there is formed continuously a mixture of the salt, detergent, and water, a gas is continuously dispersed into the material being intensively sheared, and an intimate heated plastic blend of said detergent, said gas and said builder salt is continuously discharged.

In a highly advantageous and preferred embodiment, this gas-containing plastic fiowable blend is extruded directly as a bar through an extrusion opening of suitable size (large enough to form the bar), the fiowable plastic blend being maintained continuously in a heated fiowable condition and continuously under shearing forces from the time of its formation until its passage through the extrusion opening. The mechanically applied pressure used for the extrusion is advantageously comparatively low (e.g. well below about p.s.i.g.). Advantageously, the residence time of the material in its travel from the intensive shearing zone to the extrusion opening is very short (e.g. well below 2 minutes and preferably less than 1 minute); the total residence time from initial solid-liquid contact to extrusion is also advantageously very short, generally well below 10 minutes, and preferably less than 5 minutes.

Individual laundry bars may be produced from the heated extruded porous material by hardening the extruded bar (as by cooling at room temperature) and then cutting it to a suitable size. The cutting may be effected prior to hardening.

By utilizing the process of this invention, bars of uniform texture having specific gravities well below 1.5, e.g., in the range of about 1.1-1.4, and having a microscopic pores invisible to the naked eye, distributed throughout the thickness and Width of the bar, have been formed continuously at high rates of production, without using heavy expensive equipment and without the expenditure of a large amount of energy for the extrusion operation.

The water soluble anionic organic synthetic detergents which may be present in the compositions produced in accordance with this invention contain a sulfo acid solubilizing group joined (directly or indirectly through an intermediate linkage) to a hydrophobic organic group. Thus, such detergents include both organic sulfonates, e.g. RSO compounds and organic sulfates, e.g. R-O-SO compounds, having sufficient water solubility to form detersive aqueous solutions with foaming properties in concentrations which are suitable for use in laundering operations. In the formula, R is a radical having an aliphatic chain of at least six carbons, the radical preferably having about 8-30 carbons. The detergents may be used individually or in any desired combination.

Among the suitable water soluble anionic sulfonated detergents, the higher alkyl aryl sulfonate detergents having about 8 to 15 carbon atoms in the alkyl group are particularly effective. It is preferred to use the higher alkyl benzene sulfonate detergents for optimum eifects,

though other detergents containing a mononuclear aryl group, such as xylene, toluene or phenol, may be used also. The higher alkyl substituent on the aromatic nucleus may be branched or straight-chained in structure. Examples of straight chain alkyl groups are n-decyl, ndodecyl and n-tetradecyl groups derived from natural fatty acids and petroleum. Examples of branched chain alkyl derivatives are propylene and butylene polymers such as propylene trimer, tetramer and pentamer. Examples of other suitable water soluble anionic sulfonated detergents which may be satisfactorily used in the compositions of this invention are the alkane sulfonates containing about 8 to 20 carbon atoms in the alkyl group and the alkyl sulfonates wherein the alkyl group of about 8 to 20 carbon atoms is linked to the sulfonic acid group through a -COOR group, e.g. oleic acid isethionate, -CONHR group, e.g. lauric acid taurate, or a OR group, e.g. dodecyl glyceryl ether sulfonate, wherein the R is a lower alkyl or a substituted lower alkyl group containing 2-3 carbon atoms.

Among the suitable water soluble organic sulfated detergents which it is preferred to use in compositions of the invention are alkyl sulfates, e.g. sodium lauryl or coconut fatty alcohol sulfate, and the alkyl ethyleneoxy ether sulfates, e.g. sodium lauryl tri-ethyleneoxy sulfate, said alkyl groups having about 8 to 20 carbon atoms and the ethyleneoxy sulfates containing about 1 to 15, preferably 2 to moles of ethylene oxide. The alkyl groups may be derived from naturally occurring glycerides or synthetically from petroleum, e.g. cracked waxes or ethylene polymerization.

Other suitable organic sulfate detergents include sulfuric acid esters of polyhydric alcohols incompletely esterified with higher fatty acids, e.g. coconut oil monoglyceride monosulfate, and sulfated higher alkyl phenolethylene oxide condensates having an average of about 2 to 18 moles of ethylene oxide per phenol group and about 6 to 10 carbons in the alkyl group. The sulfated higher alkyl phenol-ethylene oxide condensates which it is preferred to employ have about 4 to 6 moles of ethylene oxide per phenol group and about 8 to 12 carbon atoms in the alkyl group.

In one preferred form of the invention, these sulfate and sulfonate detergents advantageously are supplied to the shearing zone in an acid liquid state and are present in the final product in the form of their alkali metal or alkaline earth metal salts. The preferred alkali metals are sodium and potassium and the preferred alkaline earth metals are calcium and magnesium. Optimum effects are obtained with the sodium salts in general.

The proportion of anionic organic detergent should be suitably selected so as to yield a product having the desired performance and physical characteristics. The detergent active functions as a foaming and cleansing agent as well as a plasticizer in the compositions of the invention. The proportion of said detergent will be minor compared to the inorganic salts, usually in the range of about 10 to 40% by weight, and preferably about 15 to by weight, of the finished bar.

The water soluble inorganic builder salts are known in the art generally. Particularly suitable are alkali metal or alkaline earth metal salts, or combinations thereof. Ammonium or an ethanolammonium salt in a suitable amount may be added also, but generally the sodium and potassium salts or similar salts effective to add hardness or strength to the bar are preferred. Examples are the water soluble sodium and potassium phosphates, silicates, carbonates, bicarbonates, borates, sulfates and chlorides. The builder salts contribute detersive efiiciency when used in combination with sulfonic acid and/or sulfuric ester organic synthetic detergents. Particularly preferred builder salts are the alkaline builder salts such as polyphosphates, silicates, borates, etc. Inasmuch as the builder effects and processing characteristics of the individual salts vary to some extent, generally mixtures of inorganic builder salts are used in variable, predominating, proportions, e.g. about 45-85% by Weight of the finished bar, usually in the range of about -75% preferably in proportion of about 50-65% by weight.

In the Water soluble inorganic builder salt mixtures used in the detergent laundry bar compositions, it is preferred to have present a mixture of sodium tripolyphosphate and sodium or potassium bicarbonate. The combination or mixture of salts wherein the bicarbonate to tripolyphosphate ratio is selected from the range of about 1:1 to about 3:1, and which when admixed with the particular organic detergent and Water in proportions such that this mixture of inorganic salts is at least about 40% of the total weight of the manufactured bar, results in desired processing effects and produces bars having superior physical characteristics. Preferably, the proportion of this particular inorganic salt mixture is within the range of about 45 to about by weight of the manufactured bar.

Both Phase I and Phase 11 sodium tripolyphosphate and mixtures thereof may be successfully used in the compositions. The usual commercial tripolyphosphate consists mainly of the Phase II material. The commercial tripolyphosphate material is usually essentially tripolyphosphate, e.g. 87-95%, with small amounts, e.g. 4-13% of other phosphates, e.g. pyrophosphate and orthophosphate. Sodium tripolyphosphate in its hydrated form may be used also. While trisodium orthophosphate may be used in the amounts indicated, its presence often results in a bar which tends to sweat in hot, humid climates and whose surface tends to slough off more readily in such climates.

The sodium or potassium bicarbonate is an effective pH buffer and is preferred because the particular tripolyphosphate-bicarbonate mixture results in plastic detergent compositions which yield superior extruded bars. This material is also desirable in that it is relatively inexpensive, has suitable solubility and does not cause frosting on the surface of the bar. The sodium bicarbonate may be incorporated directly as anhydrous bicarbonate or in the form of sesquicarbonate, a hydrate containing both bicarbonate and carbonate.

Other suitable builder salts which may be incorporated in the built synthetic detergent bar compositions include the water soluble sodium and potassium silicates, carbonates, borates, e.g. sodium tetraborate, chlorides and sulfates, e.g. magnesium sulfate. Generally, the total proportion of these additional builder salts will be within the range of from 0.5 to 24% by weight of the manufactured bar. The sodium and potassium silicates having an Na O:SiO ratio within the range of 1:1 to about 3.5 :1 are particularly effective as corrosion inhibitors in proportions of about 1 to 8% by weight of the fiinished bar. The sodium sulfate content is advantageously kept low, e.g. below /3 the weight of the phosphate (on an anhydrous basis); preferably, to avoiding frosting, the sodium sulfate content is below about 5% of the weight of the bar.

The final essential ingredient in the built synthetic detergent bar composition is water or similar material. This component is generally present in a proportion within the range of about 2 to 30% by weight of the bar. This material serves as a plasticizer in the solid compositions produced by this invention and also helps promote the neutralization reaction. It will be appreciated that the total amount of water is the sum of the amount added with the other ingredients in the feed (e.g. in the sulfonic acid, or with the salts, or separately) and the amount formed during the neutralization reaction. It is preferred that the water be from about 4% to 25% by weight.

The neutralizing agent may be contained, in solid form, in the mixed powder fed to the intensive shearing zone, and the feed Water may be supplied in the liquid sulfonic acid portion of the feed. With certain detergent acids (such as long chain alkylbenzene sulfonic acids) the presence of the desired quantity of feed water causes partial gelation of the sulfonic acid-water blend, so that there are difficulties in metering the blend accurately to the intensive shearing apparatus. In the practice of our invention we have been able to avoid this difficulty by adding the feed water continuously in a separate stream; advantageously, when the powder contains an ingredient (e.g. unhydrated sodium tripolyphosphate) which tends to form hydrated crystals on contact with water, this separate stream of feed water is introduced into the intensive shearing apparatus downstream of the point where the liquid detergent acid is fed, so as to allow intimate prior contact between the acid and the unhydrated material. Preferably this addition is made just slightly downstream of the point of contact of the acid and powder, so that the moving builder salts come into contact with the water within a few seconds after their contact with the acid. Our invention also makes it possible to use a liquid neutralizing agent and to employ alkali metal hydroxides as the neutralizing agents. Thus, an aqueous solution of sodium hydroxide (e.g. of about 20 to 75% concentration) may be used as the neutralizing agent, alone, or in conjunction with a solid neutralizing agent. It is advantageous to add the stream of aqueous alkali metal hydroxide at a stage upstream of the point where the liquid detergent acid is introduced, particularly when the builder salt mixture contains material (such as solid carbonate and/ or bicarbonate) which can act as a neutralizing agent; such upstream addition insures that the detergent acid will react preferentially with the alkali metal hydroxide instead of with the carbonate or bicarbonate, even though the moving builder salts come into contact with the added alkali within a few second prior to the time the mixture comes into contact with the acid. Highly alkaline silicates such as alkaline sodium silicate may also be used as neutralizing agents, advantageously as aqueous solutions added in the same manner as the sodium hydroxide.

Optionally, a fatty acid alkylolamide may be included in the composition of this invention. Such materials are generally condensation products of higher fatty acids having about 10l8, preferably 1014, carbon atoms in the acyl group with alkylolamines selected from the group consisting of monoethanolamine, diethanolamine and isopropanol-amine. Examples are lauric, capric, myristic and coconut monoethanolamide, diethanolamide and isopropanolamide and the ethylene oxide adducts of such amides, (advantageously with small amounts, e.g. 1 to 2 moles, of ethylene oxide per mole of amide). The alkylolamides, which often act as suds builders, may be present in proportions within the range of about to 5%, preferably about 2%.

Various other ingredients may be included if desired, The compositions may beneficially include specific chelating agents capable of complexing iron such as the water soluble salts of ethylene diamine tetraacetic acid and the like. Other conventional auxiliary materials which may be incorporated in the compositions are soil-suspending agents such as sodium carboxymethylcellulose, tarnish inhibitors such as melamine, fluorescent brightening agents, perfumes, coloring agents, germicides or bacteriostats, other detergent materials such as water-soluble non-ionic, amphoteric and cationic surfactants or watersoluble and insoluble soaps, skin-conditioning agents such as glycerine or lanoline, and the like. These materials may be admixed with the compositions in any suitable manner which does not substantially adversely affect the plasticity of the compositions, and are preferably present in minor amounts relative to the synthetic anionic detergents.

Other ingredients which may be employed are starches (such as tapioca flour, cornstarch, yucca starch or potato starch); the presence of the starch aids in the processing of the mixture, improves its workability and appears to promote its flow over the inner walls of the bar-forming die of the plodder. Other agents which have related effects, and which may be added together with or in place of the starch, are clays such as bentonite and kaolin, which like starch tend to absorb moisture and swell to form gels in hot aqueous media, zinc oxide and finely divided cellulose (Solka-Floc), These additives may be included in amounts up to about 20%; their effects are marked above about 5% (e.g. 7%); a preferred proportion is about 1()12% of starch. Starch also helps to give the bar a brighter color.

Another processing aid is a wax such as paraffin, which may be added as fine flakes mixed with the builder salts or dissolved or dispersed in heated detergent sulfonic acid. Related waxy materials such as petrolatum may also be used. The wax also helps to increase the life of the bar in ordinary use and to prevent sweating of the bar in certain climates, when used in small amounts (e.g. A1 to l%%); smaller and larger amounts may be used as desired.

Among the particular detergent acid materials which may be used in the process are the industrially available alkyl aryl sulfonic acids having an average molecular weight in the range of about 270 to 380, preferably from about 300 to 380, prepared by sulfonating the corresponding alkyl aryl hydrocarbon with a sulfonating agent such as sulfur trioxide, oleum or sulfuric acid to yield a liquid composition containing about 65-99% sulfonic acid, about 1-34% sulfuric acid or sulfur trioxide monohydrate, O.52% sulfonation by-products and about 0.10% Water.

The neutralizing agent used in the process (advantageously alkali metal, preferably sodium or potassium, carbonate, oxide or hydroxide) may, as indicated previously, be employed in solid hydrated or unhydrated form, e.g. as dry finely divided particles pre-mixed with the inorganic builder salt, or they may be supplied as aqueous solutions or slurries. The carbonates and bicarbonates generally are used in solid form. Advantageously there is present an amount of neutralizing agent at least equal to the amount stoichrimetrically necessary for complete neutralization of the detergent acid and any acid constituents (such as sulfuric acid) accompanying the detergent acid.

When the neutralizing agent is a suitable carbonate or bicarbonate, the inorganic builder salt may comprise only the neutralizing salt itself, in which case the neutralizing salt is usually present in excess of the stoichriometric quantity needed to completely neutralize the liquid organic sulfo acid containing material. For best results, however, additional inorganic builder salts (e.g. polyphosphates) should also be present with the particulate neutralizing agent to enhance the performance characteristics of the built detergent product. It is found that when excess unreacted soda ash is present in the final bar, the product is less advantageous in that it is not as smooth or as free from bloom.

The amount of Water (including water of neutralization) present in the intensive shearing zone will generally be varied in accordance with the type and amount of anionic detergent formed therein. It should, however, be sufiicient to impart some plasticity to the anionic detergent at the temperature of the shearing operation. Ordinarily, it is advantageous to supply some water in addition to the water of neutralization. The amount of water present is such that the composition is plastic without the need for an intermediate drying step. Water present in salt hydrates which are stable under the conditions prevailing in the shearing zone will generally not be available for plasticiza= tion.

The heat liberated by the neutralization reaction raises the temperature of the mixture of builder salt and anionic detergent and makes the mixture more plastic and workable in the intensive shearing zone. The temperature attained in this zone will naturally depend also on the amounts and heat capacities of the builder salt and other ingredients present, as well as the amount of heat generated by the shearing. In some cases it is advantageous to abstract some of the heat from the mixture, as by circulating cooling fluid around the shearing zone. The evaporation occasioned by the injection of the gas into the mixture may also have a cooling effect. It has been found, however, that the process may operate over a wide range of temperatures of the material being extruded from the intensive shearing zone; for example, temperatures in the range of about 100 to 200 F.

As previously mentioned, the neutralization reaction takes place very rapidly in the zone of intense shearing. In a preferred form of the invention, the material emerging from that zone is practically completely neutralized as evidenced by an indicator incorporation test. A satisfactory test for determination of the completion of the neutralization from the practical standpoint is by the incorporation of a suitable dye as an indicator which normally changes color at a pH of about 3 to 4 in water, such as Pylaklor Detergent Blue S5OO or Bromphenol blue. For example, the Pylaklor dye preferably dissolved in water is added at a suitable inlet in a concentration of about 0.01% of the finished formula weight (for example, with an amount of water corresponding to about 12% of the finished formula weight) with the inorganic salts and sulfonic acid. Where the mixture being discharged is essentially pink in color to the eye, then insufiicient neutralization has occurred, whereas a non-pinkish color, e.g. bluish, means that the neutralization is practically complete.

The gas used in the process is preferably air, which is 9 obviously the cheapest and most available. It is, however, within the broad scope of this invention to employ other gases such as nitrogen, carbon dioxide, etc.

The process does not require high gas injection pressures. A significant decrease in the density of the product has been attained even when the gas pressure at the point of injection was only slightly above atmospheric. Pressures well below 100 p.s.i.g., e.g. on the order of about 20 to 60 p.s.i.g., have given excellent results.

The gasification treatment has been found to produce an intimate extrudable blend which flows readily at low mechanically applied pressures but still retains its shape on extrusion.

Apparatus suitable for carrying out the process of this invention is illustrated in the accompanying drawings in which:

FIGURE 1 is a side view of the apparatus;

FIGURE 2 is a plan view with parts in cross-section;

FIGURES 3-6 are end views showing different positions of the paddles used for mixing and intensive shears;

FIGURE 7 is an end view of one type of paddle, which acts also to advance the material along the apparatus;

FIGURE 8 is a top view of the tip section of the paddle of FIG. 7;

FIGURE 9 is an end view showing one arrangement of the paddles;

FIGURE 10 is a side view, with parts in cross-section, showing another arrangement for discharging the material in the form of a bar or slab;

FIGURE 11 is a view of an end wall shown in FIG. 10, looking downstream;

FIGURE 12 is a side view, partly in cross-section, showing still another extrusion arrangement;

FIGURE 13 is an end view of the end wall shown in FIG. 12; and

FIGURE 14 is an overall schematic view showing one operating sequence.

The apparatus includes a jacketed housing 11 within which there are mounted a pair of parallel rotatable shafts 12 (FIG. 2), each extending horizontally the full length of the housing and each having mounted thereon, for rotation therewith, feed screw elements 13 and agitator elements or paddles 14. The longitudinal cavity within the housing is made up of two intersecting circular cylindrical zones (as can be seen from the end view in FIG. 3) meeting at upper and lower ridges 16 and 17, respectively, each such cylindrical zone being coaxial with the rotatable shaft situated in said zone, there being a small radial clearance between the inner walls of the cavity and the outer peripheries of the paddles and feed screw elements. There is an opening or hopper 18 at end of the housing, above the feed screw elements and a plurality of spaced injection ports 19, 21, 22 and 23 communicating with the lower portion of the cavity.

The two shafts are adapted to be driven in the same direction by a drive motor and gear arrangement 26 situated at one end of the housing. The feed screw elements on the shafts are of conventional helical type, suitably intermeshing in well-known fashion as the shafts rotate to advance the material, supplied through the hopper 18, in an axial direction towards the paddles.

The paddles 14 are arranged in matching pairs, the design being such that a tip 27 (FIG. 3) of one paddle of each pair is always moving in wiping relationship to an edge or flank 28 of the other paddle of the pair during the continuous co-rotation of the shafts. In the construction shown, the paddles of any pair are identical with each other and mounted with their long axes LA (FIG. 4) at right angles, the edges 28 of each paddle being defined by equiradial symmetrical arcs whose centers are symmetrically situated on the prolongations of the short axis SA of the paddle. As will be seen from the sequence shown in FIGS. 3 to 6, during the co-rotation of the shafts about their rotational axes RA, one tip 27 of the left hand paddle follows along an edge 28 of the right hand paddle, two tips of the paddles then meet, after which a tip of the right hand paddle follows along an edge of the left hand paddle. Thus, in a full 360 rotation, each edge of each paddle will be wiped once by a tip of its matching paddle. During this full 360 rotation, the internal walls of the housing 11 will be wiped twice by the tips of the paddles.

Certain paddles are designed to advance the material longitudinally of the shafts. In these paddles (hereinafter called advancing paddles), the profile of the rear face 31 (FIGS. 7 and 8) of the paddle 14 is offset by a slight angle a (about the axis of rotation) from the profile of its front face 32. For example, for a paddle having its long axis 4% inches long and its short axis 2 inches long, and having a thickness of 1 inch, the two faces may be offset by an angle of l2 /2. The other paddle of the same pair has the profiles of its faces similarly offset by the identical angle, the design being such that the edge of flank of each paddle will be wiped by the tip of its paired paddle, as previously described. Thus, in any cross-section, through the pair of paddles, at right angles to the axis of rotation, the relationship of the cross-sectional profiles will be the same as that shown in FIGS. 3 to 6. To advance the material from the hopper end of the housing toward its opposite end, the profile at the rear face of the paddle (that is the face nearest the hopper end) is preferably offset (from the profile at its front face) in the same direction as the direction of rotation of the paddles illustrated by the arrows in FIG. 7. It will be appreciated that while the tips are shown as being relatively sharp in the drawings, they may be relatively blunt, as indicated by the dotted lines on FIG. 7, the dimensions being adjusted so that the tips, though blunt, still are in close wiping relationship with the inner walls of the housing and with the edges of the matching paddle.

To continue the longitudinal advance of the material, in a more or less helical path, the long axes of each successive pair of paddles may be offset, by an acute angle, from the long axes of the pair previously engaged by the material being treated. FIG. 9 (in which the arrows indicate the direction of rotation of the shafts) illustrates various positions of the front faces of successive paddles, the paddle designated as I being nearer to the discharge end of the machine than the other paddles; the paddle II being next, then the paddle III and then the paddle IV which is furthest from the discharge end, there being a 45 angle between the long axes of successive paddles. This offsetting of the long axes of adjacent paddles also aids in the mixing action of the apparatus. As will be seen from FIG. 9, when the paddles are in the position designated as II, for example, their further movement acts to compress the material between the edges or flanks of the paddles and the walls of the housing, forcing the material into the paths of the movement of adjacent pairs of paddles.

The front and rear faces 32, 31 of the paddles are advantageously flat and, when the paddles are mounted on the shafts and situated in planes perpendicular to said shafts, the faces of adjacent paddles are preferably close to each other; thus the clearance between the front face of one paddle and the rear face of the next paddle may be on the order of about 0.03 inch. The clearances between the tips of the paddles and the inner walls of the housing may be, for example, about 0.03-0.04 inch; the clearances between the tip of the paddles and the edges of the paired paddles which they wipe may be about the same, eg about 0.03 inch.

At the discharge end of the apparatus, several arrangements may be employed for extruding the material. In one arrangement (illustrated in FIGS. 10 and 11) there is an adjustably mounted end wall 35 having a rearwardly projecting skirt 36 dimensioned to fit closely within the walls of the housing 11, whose shape at this point is a symmetrical oval (formed by two spaced opposed vertical semicircles, of the same diameter and aligned with the corresponding inner walls of the main cavity in the housing, joined by tangent horizontal lines). The material leaving the last paddles 14 flows between the lower wall 37 of the housing and the bottom portion 38 of the end Wall 35. The skirt prevents flow of the material out of the sides and top of the discharge end. Smooth outward flow is aided by the presence of an inclined apron 39 extending downward from the lower wall 37.

In another extrusion arrangement, illustrated in FIG. 2, there is a fixed end wall 41 completely blocking the end of the housing 11 (and having circular openings to closely receive the shafts) and a rectangular horizontal discharge tube 42 leading from the space adjacent the last group of paddles. With this arrangement, particularly good results have been obtained when successive paddles nearest the discharge end have their long axes offset at a relatively large angle (preferably at the maximum, 90, angle), as illustrated in FIG. 2 in which the sequence of the last five pairs of paddles is I, III, I, III, I (using the terminology discussed above and illustrated in FIG. 9).

In still another extrusion arrangement, shown in FIGS. 12 and 13, there is a fixed end wall 44 having a rectangular bar-sized discharge opening 45 therein, but otherwise completely blocking the end of the housing, the discharge opening being eccentrically arranged with respect to the center line of the cavity in the housing and located nearer to that side of the housing which corresponds to the side where the motion of the paddle tips has a generally upward, rather than downward, component.

In the operating sequence shown in FIG. 14, the extruded bar 51 continuously leaving the discharge tube 42 is taken up on a moving endless belt 52, cooled and aged to harden it, passed through a conventional cutting device 53 and then stamped at 54.

Cooling water or other cooling or heating fluid may be passed through any desired portion of the jacket 56 of housing 11.

In the use of the illustrated apparatus, best results have thus far been obtained when the speed of rotation is such that there are about 7000-11000 paddle cuts per minute; (a paddle cut occurs between the paddles of successive pairs each time the paddle of one pair, on one shaft, passes in close shearing relationship with a paddle of the other pair, on the other shaft; for example, in FIG. 9 paddle I on the left hand shaft and paddle II on the right hand shaft are just beginning to make a cut. With all the pairs of paddles offset as shown in FIG. 9 of the drawing, there will be two cuts per full rotation; for example, with 26 pairs of paddles [of 5-inch length], using a preferred speed of 175 rpm, there will be 26 175 2:9,000 paddle cuts per minute).

Typically, the extrusion opening may have an area of at least 2 square inches and a height (at least equivalent to the thickness of the individual bars) in the range of about to 3 inches, and a width of at least about 2 inches. The width of the extrusion opening may be equal to the width of a single bar, or may be a multiple of that width, in which case the extrudate may be cut lengthwise before or after it is fully cooled and hardened (e.g. by pulling or pushing it past one or more cutting elements, such as thin vertical wires which may be heated to facilitate the cutting).

The preferred extrusion temepratures are above F. One suitable range is about 140 F.; the periphery of the extrusion opening may be heated to a temperature above (e.g. 1020 F. above) that of the extrudate to promote the extrusion. It has been found, however, that much higher extrusion temperatures may be employed, yielding special effects. Thus, in runs involving continuous neutralization (an exothermic reaction which tends to heat the product considerably, as previously noted) there was produced an extrudate having a temperature above F. (e.g. 186 F.) which extruded smoothly, as a bar, from the discharge opening, retaining the crosssection of that opening (in this case, a side discharge tube such as that shown at 42, rectangular in cross-section). The extruded material at this relatively high temperature was found to be considerably tougher and stronger than similar extrudates at lower temperatures.

In a preferred form of the invention, the process is operated in such fashion that the material being fed to the intensive shearing zone forms a plug capable of retaining the gas injected into that zone and substantially preventing the gas from blowing back and leaving that zone through the feed end. Operation with the apparatus illustrated in the drawing and in the manner described in the following Example I, using pre-neutralized detergent effectively avoids such blowback; in such operation the temperatures near the feed end of the intensive shearing zone are generally relatively low, usually lower than those near the discharge end, so that the mixture adjacent the feed end is more resistant to flow (e.g. more viscous). When the continuous neutralization procedure is used, blowback will occur at times, presumably due to the fact that the exothermic heat is usually generated adjacent the feed end, raising the temperature there and making the ingredients less viscous and less likely to form an airretaining plug. This effect can be prevented or reduced by suitable modifications to make the configuration, dimensions, and temperature of the material at the feed end such that its resistance to air flow is increased. For example, the circumferential edges of the feed screw flights can be made broad and flat, rather than sharp, so as to increase the area of contact between the flight edges and the stationary internal Well of the housing; other arrangements to seal the feed end more effectively may be used, e.g. in place of the open hopper 18 there may be an enclosed tube of small diameter, having a feed screw operating therein, arranged at an angle (e.g. feeding downward at 90 to the shafts 12).

The following examples are given to illustrate this invention further:

EXAMPLE 1 Into the hopper of a device as illustrated in FIGS. 1 and 2, there was continuously fed 605 pounds per hour of a dry blend of detergent and builder salt (through the hopper 18) at room temperature and 75 pounds per hour of cold water (through the port 21) containing a minor amount of a blue dye, while air was continuously injected into the lower portions of the resulting mixture at a pressure of 60 p.s.i.g. (measured just outside the ports 22 and 23, through which the air was supplied). The dry blend contained 33.1% of sodium linear alkyl benzenesulfonate (the linear alkyl radicals having an average of 13 carbon atoms and being about 15 mole percent C12, 55 mole percent C13 and 30 mole percent C14, the alkyl substitucnt containing about 20% of akyl groups whose benzene attachment is on the 2-carbon of the alkyl group, the remainder of its alkyl groups having the benzene attachment on the 3-, or higher, carbon atom), 12.3% tapioca flour, 32% sodium bicarbonate, 22.4% pentasodium tripolyphosphate (commercial grade anhydrous), together with minor amounts of perfume and impurities. Each of the paired feed screw elements was composed of four helical turns extending about 8 inches on the shafts, and the pattern of paddles thereafter (using A to designate advancing paddles, as shown in FIGS. 7 and 8, and N to designate the nonadvancing paddles) was 6A (meaning 6 successive pairs of advancing paddles), 1N (meaning one pair of non-advancing paddles), 3A, 1N, 3A, 1N, 3A, 1N, 3A, SA. All the paddles were arranged at 45 to the preceding and succeeding paddles, except for the last five paddles, for which this angle was 90. The water injection port 21 was at a point about 9 inches forward of the forward end of the feed screw section, one air injection port 22 was at a point about 9 inches forward of port 21, and the second air injection port was at a point about 7 inches forward of port 22, and within the length of the 90 five-paddle section. The dimensions of the paddles and the clearances were those described earlier in this specification. The discharge tube 42 was rectangular, about 2 inches wide and about 1 inch high, and 6 inches long; extended tube served as a zone for compacting the material being extruded. The speed of rotation of the shafts was about 175 rpm. corresponding to about 9400 paddle cuts per minute. The residence time of the material in the apparatus was less than minutes (the free volume of the apparatus, per se, was about 0.4 cu. ft.). The material emerging from the discharge tube had a temperature of about 130 F. It retained the shape of the cross-section of the tube without significant slump, the thickness, width and shape of the extruded bar being substantially the same as the height, width, and shape of the extrusion opening. After it had been permitted to cool and harden, its density was about 1.25.

During the run there was no indication of leakage of air from the apparatus, either from its joints or from the feed end. Apparently the air was prevented from blowing back past the feed end by the presence of the pasty mass of material which was being advanced toward the discharge end by the action of the feed screw elements and the advancing paddles. This pasty mass was at a lower temperature, and therefore was presumably more resistant to flow (more viscous) than the more extensively worked material nearer the discharge end of the apparatus.

By increasing the proportion of water (e.g. to about 100 lbs./hr.), products having a density of about 1.15, and even about 1.07, after hardening at room temperature were obtained.

In this example (as in the following examples), hydration of the hydratable salts (e.g. the sodium tripolyphosphate) in the mixture was largely incomplete during the mixing and extruding; the hydration occurring thereafter, on standing, contributed to the hardness of the product. This hydration appeared to take place substantially uniformly throughout the cross-section of the bar; in penetrometer tests on a bar, made in a similar manner and aged one day at room temperature after wrapping, the penetration measured at. the outer surface of the bar, was 2.0 mm., which was the same as the penetration measured on a freshly exposed surface about /3 inch from the outer surface of the day-old bar (the new surface being exposed by carefully cutting away a portion of the bar with a sharp razor blade, without compressing the surface). The warm material emerging from the extrusion nozzle could be deformed easily, yielding readily to pressure with the fingers and was not sticky.

In these examples the material was subjected to intensive shearing forces in one portion of the apparatus and to lesser, but significant, shearing forces during its subsequent flow through the discharge portions of the apparatus (said shearing forces accompanying the flow of the pasty material under pressure), and there was no stage during its travel through the apparatus that the material was in a quiescent state in which it had an opportunity to set.

The extrusion pressures mechanically generated by the apparatus of these examples (i.e. the pressures generated when operating under the same conditions but without injecting air into the apparatus) were relatively low; for example, a pressure gauge connected to ports 22 and 23 indicated a pressure of about 40-50 p.s.i.g. (when the air supply was shut off).

The gas pockets, or pores, in the bars were microscopic and, under the microscope, appeared to be discrete and unconnected; the bars were quite free, throughout their thickness, of pores that were of such size as to be visible to the naked eye.

The density of the freshly hardened bar was also substantially uniform throughout its thickness.

The penetrometer measurements, previously mentioned, were made with a standard penetrometer needle (made from 0.41 inch diameter wire with the point ground and honed at an angle of 12) under a load of 151 grams, the reading being taken 15 seconds after application of the load.

EXAMPLE 2 In this example, the apparatus shown in FIGS. 1, 10 and 11 was employed. The dry material, fed into the hopper at the rate of about 776 lb./hr., containing 12.3% sodium carbonate (commercial grade, anhydrous), 35.8% sodium sesquicarbonate (a hydrate), 31.1% pentasodium tripolyphosphate (commercial grade, anhydrous), 17.1% tapioca flour, 3.1% sodium toluene sulfonate, together with perfume and titanium dioxide. Through port 19 (leading into lower portion of the section containing the feed screw flights) there was injected 294 lb./hr. of an acidic stream containing 96% of branched chain alkyl benzene sulfonic acid (the alkyl group having an average of 13 carbon atoms, derived from lower polymers of propylene), 2% H 1% moisture and 1% by-prodnets and impurities of the sulfonation reaction. Ports 21, 22 and 23 were located as in Example 1. Into port 21 (leading into the lower portion of the section containing the paddles, near the feed end of the apparatus) there was injected 135 lb./hr. of water containing an indicator dye (Pylaklor Blue) which turns blue when the acid is neutralized. Air was injected into ports 22 and 23. The feed screw elements were arranged as in Example 1, but the paddle pattern was 5A, 1N, 3A, 1N, 4A, 1N, 3A, 1N, 3A, 1N, 5A, all paddles being arranged at 45 to the preceding and succeeding paddles. The material was continuously extruded as a continuous slab of a width of about 9 /2 inches and a thickness of about 1 /2 inch; the temperature of the slab as it was extruded was well over F. After cooling and hardening, the slab had a specific gravity of 1.39. It was cut into individual laundry bars and pressed in a conventional soap press.

EXAMPLE 3 In this example the apparatus used was similar to that described in Example 1 except that the sequence of paddles starting from the feed end was: 6A, 1N, 3A, 1N, 3A, 1N, 3A, 1N, 9A (the long axis of each paddle being offset, as in Example 1, 45 from the long axes of the preceding and succeeding paddles, except that for the last five paddles, adjacent the discharge end, this angle of offset was 90). The discharge was effected through a horizontal rectangular side discharge tube about 2 inches wide, about 1 inch high and about 6 inches long, whose long axis was at right angles to the axes of the shafts, which led from a point on the lower portion of the housing adjacent the last few paddles, being situated on that side of the housing where the paddles had a downward movement. (The end wall of the apparatus in this case was constructed to block completely any discharge of material through said end wall.)

A stream of dry-blended, screened (but not pulverized) solid ingredients, of the following composition, was fed to the hopper at the rate of 624 lbs./hr.:

All the salts were anhydrous.

The same detergent acid as used in Example 2 was fed at the same point as in that example, at a rate of 415 lbs/hr.

A stream of cold water and a very small amount of blue dye was fed to the port 21 at the rate of 70% lbs/hr.

Air under a pressure of about 65 p.s.i.g. was injected continuously through the ports 22, 23.

No cooling water was employed in the jacket of the apparatus.

The bar emerging continuously from the discharge tube had a temperature of about 186 F. It extruded smoothly, retaining the cross-section of the extrusion opening without significant slump, and was not sticky. After cooling, it was cut transversely to form individual bars.

The density of the bars was about 1.3.

Similar results were obtained when, instead of a discharge tube of substantially uniform cross-section along its length, there was employed a discharge tube of the tapered, converging type, whose cross-section at its inlet end was larger than that of the extrusion opening.

The extruded material at this relatively high temperature of 186 F. was found to be considerably tougher than similar extrudates at lower temperatures; it had sufiicient strength so that during the continuous extrusion, the hot bar (about 2 inches wide and about 1 inch in height) leaving the tube supported its own weight over a span, measured horizontally, of 4 feet or more forming a catenary curve whose lowest point was on the order of about 2 feet below the level of the two ends of that span.

EXAMPLE 4 Example 3 is repeated except that the stream of solids, supplied at the rate of 407 lb./hr., had the following composition:

52.1% of sodium sesquicarbonate (a hydrate) 29.5% of sodium tripolyphosphate (commercial grade anhydrous) 16.2% tapioca starch plus T i and perfume.

The sulfonic acid stream is supplied to port 21 (rather than port 19) at the rate of 117 lbs/hr. Instead of a simple water-color mixture, there is supplied 76 lbs/hr. of a caustic-water-color stream containing 59% water and 40.9% of a 48.9% solution of NaOH in water; this is added at port 19 (rather than port 21).

14 EXAMPLE 5 In this example, the apparatus was like that of Example 3 except that the paddle pattern was: 3A, 1N, 3A, IN, IA, 1N (after which the 1A, 1N sequence was repeated 11 times more). The stream of solids had the following composition, all the ingredients being anhydrous:

Percent Soda ash 16.9 Sodium bicarbonate 40.7 Trisodium phosphate 5.8 Sodium tripolyphosphate 28.6 Sodium sulfate 3.5 Carboxymethylcellulose .6- Sodium chloride .3 Lauric-myristic isopropanolamide 3.1 Q.S. perfume.

The detergent sulfonic acid stream was a branched chain alkyl benzene sulfonic acid, as in Example 2. The relative proportions of the three streams (i.e., solidszacidzwater) were about 11:4:1, and the total rate of feed wa about 800 lbs/hr. Air was supplied through port 23 at a pressure about 12 p.s.i. above the pressure mechanically generated by the apparatus (i.e., the pressure generated when operating under the same conditions but without air injection, which mechanically generated pressure was on the order of about 25 p.s.i.g. in this example). The material was discharged at a temperature of F. through the discharge tube which, in this case, was also externally heated by a small electric heater. The extruded bar had a density of about 1.4, had a content of anionically active material (as determined by conventional titration with a cationic agent) of 25% and a moisture content of 10 /2%.

Using streams of the same composition and operating at a total feed rate of about 1000 lbs/hr. (with air at a pressure 2-3 p.s.i. above the mechanically generated pressure) there was obtained a bar of density 1.32 having a moisture content of 14%% and a content of anionically active material of 22%.

The foregoing examples have dealt with processes in which a stream of air was injected. The air may also be introduced in other forms; for example, spray-dried hollow particles, or beads, of well known structure, of the pre-neutralized detergent (i.e. alkyl benzene sulfonate, which may be blended with sodium silicate as in US. Patent 2,515,577 of July 18, 1950) may be used as the detergent feed material under conditions such that the air contained within these particles (e.g., air encapsulated in the particles) is in large part retained within the mass of material being blended; by operating in this manner, without injection of a stream of air, using substantially the same procedure and basic formulation as described in Example 1, and employing spray-dried hollow particles as the detergent feedstock, bars of density 1.35-1.4 have been produced.

Typically, a cross section of the bar (such as a surface exposed by careful slicing) appears, under the microscope, as a relatively loose aggregation of materials including builder salt crystals and starch grains (when starch is used as a component) with numerous discrete spaces or interstices distributed throughout the mass, some of the interstices being as small as the starch grains (10-15 microns in diameter) and others, less numerous, being considerably larger (e.g., 20 times the diameter of the starch grains). The largest crystals are on the order of 200-300 microns long and about 2050 microns wide, and there are numerous crystals of much smaller size.

Although the present invention has been described with reference to particular embodiments and examples, it will be apparent to those skilled in the art that variations and modifications can be substituted therefor without departing from the principles and true spirit of the invention.

What is claimed is:

1. Process for the production of detergent laundry bars which comprises continuously feeding finely divided solid water-soluble inorganic hydratable builder salt to a zone in which there is formed a mixture of said salt, a synthetic anionic detergent, starch, and Water and in which the ingredients of said mixture are continuously intensively sheared together to form a heated flowable blend and continuously. forwarded through said zone, continuously dispersing gas into the material being intensively sheared, and continuously discharging an intimate plastic blend of said detergent, said dispersed gas, said starch and said builder salt from said zone, said process including the steps of extruding said heated flowable blend through a heated extrusion opening of such size that said blend is extruded continuously from said extrusion opening as a mass whose cross-section has a thickness of at least about inch and an area of at least about 2 square inches, said flowable blend being maintained continuously in a flowable condition and continuously under shearing forces from the time of the formation of said blend until its passage through said extrusion opening, hardening said extruded mass and subdividing said mass into detergent laundry bars, said detergent being a synthetic anionic sulfonate salt detergent and being formed in said zone by the exothermic reaction of a basic neutralizing agent with the corresponding detergent sulfonic acid in liquid state in the presence of solid pentasodium tripoly' phosphate builder salt supplied to said zone in finely divided substantially unhydrated form, the process being one in which the extruded blend contains partially hydrated water soluble inorganic builder salts including partially hydrated pentasodium tripolyphosphate and in which hydration of said salts occurs during, and contributes to, the hardening of said extruded mass, said gas being selected from the group consisting of air, CO and N the proportions of the ingredients, based on the weight of the finished mixture being in the ranges of about 10 to 40% of the synthetic anionic detergent, about 45 to 85% of the builder salt, about 10-12% of starch, and about 2 to 30% of water.

2. Process as set forth in claim 1 in which the material leaves said extrusion opening within 2 minutes of leaving the intensive shearing zone and in which the heated extrusion opening is maintained at a temperature of about 10 to F. above the temperature of the extruded mass.

3. Process as set forth in claim 1 in which said extrusion takes place under a mechanically applied pressure below about 100 p.s.i.g.

4. Process as set forth in claim 3 in which said gas is air, the air being injected at a pressure of up to about 100 p.s.i.g.

5. Process as set forth in claim 4 in which the air pressure is about 20 to 100 p.s.i.g.

6. Process as set forth in claim 1 in which the material leaves said extrusion opening within about one minute of leaving the intensive shearing zone and in which said extrusion takes place under a mechanically applied pressure below about 60 p.s.i.g.

7. Process as set forth in claim 1 in which said neutralizing agent is selected from the group consisting of sodium and potassium carbonate, oxide and hydroxide.

8. Process as set forth in claim 1 in which said detergent acid is a higher alkyl benzene sulfonic acid and said finely divided builder salt comprises sodium carbonate, at least a portion of said sodium carbonate acting as a neutralizing agent by reacting with said acid.

9. Process as set forth in claim 7 in which said detergent acid is a higher alkyl benzene sulfonic acid and said neutralizing agent is sodium hydroxide, said sodium hydroxide being supplied in aqueous solution to said zone.

10. Process as in claim 1 in which said zone is an enclosed space into one end of which the ingredients of the mixture are fed and from the other end of which the resulting heated flowable blend containing dispersed gas is extruded through an extrusion opening as a mass whose cross-section has a thickness of at least about inch and an area of at least about 2 square inches, said fiowable blend being maintained continuously in a flowable condition and continuously under shearing forces from the time of the formation of said blend until its passage through said extrusion opening, said extruded mass is then hardened and subdivided into detergent laundry bars, said process including the steps of injecting air into said zone at a superatmospheric pressure greater than the pressure mechanically generated in said zone, while substantially preventing the escape of air from the feed end of said zone by forming, of the materials being fed to said zone, a plug capable of retaining the air injected into said zone, said extruded mass containing finely divided partially hydrated builder salt including pentasodium tripolyphosphate, the hydration of said builder salt occurring during, and contributing to, the hardening of said extruded mass, the proportions of the ingredients fed to said zone being such that the bars contain about 10- synthetic anionic detergent, about to of a mixture of sodium tripolyphosphate and sodium bicarbonate or sodium sesquicarbonate, about 10-20% of starch, and about 4 to 25% water, the total residence time in said zone, from the initial contact of the solid builder salt and the liquid in said zone to the extrusion of the blend through said extrusion opening, being below 10 minutes, said bars having a density of about 1.3 to 1.4, having gas pockets distributed therethrough, and containing crystals of hydrated pentasodium tripolyphosphate.

11. Process as in claim 10 in which the sulfonate detergent is sodium alkylbenzenesulfonate having about 13 carbons in the alkyl, said sulfonate detergent is present in amount of above 15 to 30% in said bars, said basic neutralizing agent is sodium hydroxide or sodium carbonate, and the air is injected at a pressure of about 20 to p.s.i.g., the gas pockets in the bars are microscopic and distributed substantially throughout said bars, and said bars consist essentially of said sulfonate detergent, said builder salt, said starch, and water.

References Cited UNITED STATES PATENTS 2,407,647 9/ 1946 Bodman 252--121 3,178,370 4/1965 Okenfuss 252-438 3,081,267 3/1963 Laskey 252 3,089,197 5/1963 Chaffee et al. 264--50 FOREIGN PATENTS 858,075 1/ 1961 Great Britain.

OTHER REFERENCES Synthetic Detergents-McCutcheon-MacNair-Dorland Co., N.Y., 1950, p. 187498.

Soaps and Detergents-Thomssem, MacNair-Dorland Co., N.Y., 1949, p. -188.

LEON D. ROSDOL, Primary Examiner P. E. WILLIS, Assistant Examiner US. Cl. X.R. 252161; 264-50

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