WO2009003787A1

WO2009003787A1 - Process and apparatus for making marbled detergent bars

Info

Publication number: WO2009003787A1
Application number: PCT/EP2008/056993
Authority: WO
Inventors: Vijay Jaykishore Daru; Umesh Laltaprasad Dubey; Saikumar Earla; Satishkumar Gopinath Nair; Meena Rajan; Raveendranathan Vadumkootil
Original assignee: Unilever N.V.; Unilever Plc; Hindustan Unilever Limited
Priority date: 2007-06-29
Filing date: 2008-06-05
Publication date: 2009-01-08
Also published as: MY161875A; BRPI0813290A2; CN101688165A; CN101688165B

Abstract

The present invention provides a process for making a shaped marbled detergent bar including the step of feeding an extrudable non-soap detergent composition into an extruder comprising at least one screw rotatably mounted within a barrel having inlet and outlet, where rotation of said screw conveys said composition from the outlet into a frusto-conically converging pressure zone, which converges into at least one nozzle from which a billet of extruded detergent emerges; and an apertured plate interspersed between said outlet ad said pressure zone. Said process additionally includes the step of injecting a coloured liquid into said composition through an injection means, located upstream of said apertured plate, the pressure of injection being higher than that generated within the extruder. Furthermore, the billet produced in said process is split once parallel to the axis of said screw, by splitting means, as it is extruded from said nozzle, so as to provide suitable marbling on the billet.

Description

PROCESS AND APPARATUS FOR MAKING MARBLED DETERGENT BARS

FIELD OF INVENTION

The present invention relates to a process and apparatus for making marbled detergent bars, particularly laundry detergent bars and more particularly non-soap detergent bars. The invention has been developed primarily for use in the manufacture of laundry detergent bars and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use.

BACKGROUND AND RELEVANT ART

Cleaning compositions in solid form are inexpensive as compared to liquids because of low cost packaging and this form is very popular, especially in developing countries. Amongst the various solid forms, bars are gaining popularity and are growing rapidly in the markets of developing countries, because of better value delivery.

Variegated, striped, marbled or mottled bars, also known in the art as multiphase bars, have been known for many years. They allow for a visually attractive mosaic pattern in the bar. This attractive pattern is highly preferred by consumers.

Multiphase bars are mainly used for skin cleansing purpose i.e. personal washing.

Thus, a marbled pattern on soap gives it a rich appearance, and stripes or other similar configurations make the soap distinctive . Multiphase bars are generally manufactured by one of the following methods:

(i) Use of mixed colour soap noodles

(ii) Use of dye-coated noodles

(iϋ) Dye injection

(iv) Co-extrusion, and

(v) Non-extrusion

Amongst these methods, dye-injection method has been widely reported.

US 3890419 (ARMOUR-DIAL INC) describes a process for preparing multiphase soap (personal wash) bars in which the dye is injected in the soap mass by way of a plurality of dye injection ports, which are present in the apertured pressure plate, that separates the barrel of the extruder from the conical pressure zone (cone) . The dye is introduced into the soap mass as it passes through the extruder and enters into the cone, the apertured plate separating the barrel and the cone. This process is for producing a striped bar, as opposed to a marbled bar.

On the other hand, GB 1316477 (UNILEVER PLC) describes a process for making multiphase soap (personal wash) bars in which dye is injected in the soap mass within the barrel of the extruder. A plurality of dye injection ports (picker pins) have been featured in the body of the barrel, as opposed to US 3890419, where the dye is injected through ports located within the apertured pressure plate. In GB' 477 the dye is introduced into the soap mass and it passes through the apertured plate and enters into the cone. The description also suggests that, as an alternative to use of picker pins, the dye could be injected through orifices disposed in the flights or shaft of hollowed out extrusion screws.

US3663671 (LEVER BROTHERS, 1980) describes a process to prepare marbled soap bars which allows a single screw extruder to extrude two streams of striped detergent material for subsequent processing into detergent tablets. The final extrusion plate has two apertures. The liquid dye is injected into the detergent mass while it passes through the single screw extruder and an apertured pressure plate into a common extrusion cone, immediately downstream of the apertured plate. It also describes a partition which is provided extending downstream from the pressure plate to separate the detergent mass into two streams into each of which liquid is injected. It has been disclosed that normally the worm in the screw extruder terminates immediately adjacent the upstream face of plate, but this could be modified so that the screw is spaced a sufficient distance from the plate to give a more equal pressure distribution over the plate surface.

The above mentioned processes are useful for making multiphase soap (personal wash) bars.

Although it may well be derived from these patents that reference to soap bars should be construed to include detergent bars and non-soap detergent bars, and that there is no criticality in the type of detergent, so long as it, together with the optional ingredients, is extrudable, the present inventors have observed that this is not the case, for the reasons mentioned below.

Multiphase detergent bars, in particular non-soap detergent bars with acceptable degree of marbling cannot be made by the methods used for making marbled soap bars. This is because the synthetic surfactants such as sodium linear alkyl benzene sulphonate used as active ingredients in detergent bars are more soluble, and hence the dyes tend to diffuse out in the body of the detergent bars very quickly. The presence of high amount of mineral material (fillers) in such bars causes the viscosity of the extrudable mass to be significantly higher than that of soap bars. Therefore, it is not possible to inject liquid dye into the extrudable mass as the back pressure that is generated due to the flow of the extrudable detergent mass is high enough to billet the pores (openings) of the dye injection means i.e. picker pins. In addition, due to the high viscosity of the extrudable mass, there is high resistance to diffusion of the dye within the mass. Further, only a portion of the liquid can be retained within the mass, as the remainder migrates to the surface of the mass as it is compressed, and forms a substantially continuous layer on the surface of the extruded bars .

Clearly the presence of a continuous layer on the final product will not provide the desired marbled appearance. It has also been observed by the present inventors that when the dye injection means are located within the apertured plate as in US 3890419, the resultant detergent bars, particularly non-soap detergent bars did not show a marbled appearance, as the dye did not mix to an appreciable extent with the detergent mass. Similarly, when the dye injection means were located within the body of the barrel as in GB 1316477, the resultant bars showed a substantially continuous layer on their surface.

An attempt has been made in the past to make multiphase (striped) non-soap detergent bars. WO2003/083034 (Unilever) describes a process wherein a striped, predominantly non-soap detergent bar composition including 5 to 50% by weight detergent active having less than 25 % soap level and 0.1 to 10 % by weight of the bar being a striping formulation including soap, non-soap or a mixture. The striping formulation includes up to 80% wt soap or up to 50% wt synthetic non-soap detergent or combinations thereof, with 5 to 30% wt water and up to 70% wt inorganic fillers. The striped detergent is made by a co- extrusion of two extrudable detergent compositions.

The present inventors have now found a process for making a multiphase detergent bar, more specifically a multiphase non- soap detergent bar that uses the dye injection method. This method has the advantage over co-extrusion method in that it is relatively simple and produces multiphase marbled bars, as opposed to striped bars.

In addition, it also offers the possibility of injecting several different colours at the same time to get intricate patterns and designs.

It is not possible to employ the processes described in prior art for the manufacture of multiphase marbled detergent bars, particularly non-soap detergent bars used for fabric wash or hard surface cleaning.

Thus there is an un-met need for a process to make multiphase marbled detergent bars, particularly non-soap detergent bars using the dye injection method.

OBJECT OF THE INVENTION

It is an object of the present invention to provide a process for making multiphase marbled detergent bars, particularly non- soap detergent bars using the dye injection method.

The present inventors have found that multiphase detergent bars, particularly non-soap detergent bars can be made using the dye-injection method if the extrudable detergent mass is passed through an apertured pressure plate, also known in the art as noodler plate, after the dye has been injected, which allows for the mixing of the dye with the mass by forming noodles, before it enters the frusto-conical pressure zone.

In addition, the provision of a distance (space) between the outlet end of the barrel of the extruder and the apertured plate, immediately before the apertured pressure plate has been found to give better control on the process as it allows for better mixing of the coloured liquid with the detergent mass.

Further, the present inventors have observed that in the case of shaped solid detergents, the billet of the detergent needs to be essentially split once, parallel to the axis of the screw of the extruder, so as to provide marbled appearance on the entire surface of the billet that is being extruded.

It has also been observed by the present inventors that the coloured liquid must be injected at a sufficiently high pressure and more specifically, at pressure that is higher than the pressure generated during the extrusion of the detergent mass. Unless the pressure is higher, the tip of the injection means billets with the detergent mass.

SUMMARY OF THE INVENTION

According to an aspect, the present invention provides a process for making a shaped marbled non-soap detergent bar including the steps of:

(i) feeding an extrudable non-soap detergent composition into an extruder including at least one screw rotatably mounted within a barrel having inlet and outlet , where rotation of the screw conveys the composition from the outlet into a frusto-conically converging pressure zone, which converges into at least one nozzle from which a billet of extruded detergent emerges; and an apertured plate interspersed between the outlet and the pressure zone;

(ii) injecting a coloured liquid into the composition through an injection means, located upstream of the apertured plate, the pressure of injection being higher than that generated within the extruder, characterized in that, the billet is split once parallel to the axis of the screw, by a splitting means, as it is extruded from the nozzle, so as to provide marbling on the billet.

Preferably, the extrusion pressure in the barrel is from 10 to 1000 psi.

Preferably the penetration value of the composition is from 1.5 to 3 mm.

Preferably the composition includes 10 to 40 wt% non-soap detergent active, 30 to 70 wt% inorganic particulate matter, and 5 to 35 wt% water.

According to another aspect, the present invention provides a product obtainable by the process according to the invention.

According to another aspect the present invention provides an apparatus for making a shaped marbled non-soap detergent bar by a process according to the invention, including an extruder including: i. a barrel having inlet and outlet, within which at least one screw is rotatably mounted, ii. a frusto-conically converging pressure zone; which is in fluid communication with the outlet of the barrel, the zone having at least one nozzle; iii. an apertured plate interspersed between the outlet and the pressure zone; iv. means for injecting a coloured liquid into the composition, located upstream of the apertured plate; and v. means for splitting the billet, parallel to the axis of the screw.

Preferably the means for splitting is a die-plate having a pair of dies, with a blade having a cutting edge, disposed therebetween, said cutting edge being oriented parallel to the axis of the screw.

The invention will now be explained in detail in the following description .

DETAILED DESCRIPTION In accordance with one aspect the present invention relates to a process for making a shaped marbled non-soap detergent bar. Cross section of the bar could be rectangular, square or circular. It is preferred that the cross-section is rectangular . The term "non-soap detergent" is used herein to include compositions containing synthetic detergents of the class of anionic, non-ionic and cationic detergents e.g. salts of alkyl sulphates, alkaryl sulphonates, alkane sulphonates and sulphonated long chain fatty acids, alcohol sulphates and ethoxylated fatty alcohols. More specifically, the term non- soap detergent is used herein to include compositions that include largely such synthetic detergents, i.e. greater than 10 % synthetic detergents and less than 20% soap i.e. alkali salt of fatty acids.

The term "soap" means alkali metal salts of fatty acids.

The detergent bars could be used for fabric washing or dish washing depending upon the composition.

The non-soap detergent composition could also be fabric washing bars of the Nil-mineral type, i.e. bars having less than 10 wt% mineral content.

The term "marbled" includes equivalent terms such as variegated or mottled, and refers to an appearance of the shaped solid detergent in which one or more coloured liquids are jumbled in a completely random fashion with the detergent mass, thereby producing the random swirling appearance of marbled shaped solid detergent. Thus, a marbled appearance is one in which numerous, discrete contrasting colour streaks or striations each with variations in width and depth along their length appear in a random array. The appearance is distinguished from mere striping in the irregularity of the striation contour and particularly by the manner in which the colour streaks are subdued at their boundaries for indistinct merger with the extruded mass. It is to be understood that this effect is not fully reproducible from bar to bar and therefore, each billet when cut into bars, will produce bars having differing marbled appearance. As the surface of these bars is abraded during use, the marbled appearance within the bars' interior will become visible. The typical final product obtainable with the present process will have the marbled effect continuing throughout the bar, so that upon wearing through use, the marbled pattern continues with subtle variation in geometry and nearly imperceptible nuance of colour change at different levels of the bar as the veins of coloration are gradually progressively exposed.

During the extrusion of the detergent mass, the extrudable detergent mass inside the frusto-conically converging pressure zone undergoes severe churning inspite of the conveying movement of extrusion. The reason for this is the high back pressure owing to the viscosity of the mass. Due to this, the mass accumulated towards the inner surface of the pressure zone gets almost smudged with the injected coloured liquid due to "churning of mass" phenomenon. The smudged mass on the pressure zone sides gets extruded along with the mass in the core of the cone and hence coats the surface of the extruded billet. The result therefore is that the marbled effect is not visible on the surface of the billet and the bars, when the billet is cut into individual bars. The present inventors have found that marbled effect can be made visible on the entire surface of the billets, as well as cut bars, by the step of splitting the billet once, parallel to the axis of the screw, and more preferably in the plane of extrusion, so as to provide marbling on the surface of the billet. The screw may have plurality of axis. The splitting may be done out-of-plane of extrusion by suitably locating the splitting means. This is done with the help of a splitting means which is a die-plate having a pair of dies, with a blade having a cutting edge, disposed therebetween, the cutting edge being oriented parallel to the axis of the screw and preferably in the plane of the extrusion. While it is preferred that the blades of the die-plate are oriented parallel to the axis of the screw, the blades can also be oriented at any other orientation w.r.t. the axis of the screw, e.g. the blades could be oriented perpendicular to the screw. The essential part is that the extruded mass is split once, and this splitting can be achieved by orienting the splitting means at any orientation. It is preferred that the billet is split into two, preferably two equal halves, as it exposes the marbling effect from the core of the mass. The core of the un-split billet then forms respective marbled surfaces of the two billets which are formed after splitting.

Additionally, it is preferred that the die-plate has a pair of slits, adjacent to each die that are capable of shaving-off the outer 1-5 mm of the surface of the billet as it emerges from the nozzle, i.e. as it is extruded. This makes the marbled appearance readily apparent from the top surface.

The process according to the invention utilises an apparatus, i.e. an extruder that includes a barrel where extrusion of the detergent mass takes place, so that the mass assumes the form of a billet. The barrel has inlet and outlet and it is preferred that distance between the outlet of the barrel and the apertured plate is from 5 to 500 mm, more preferably from 250 to 350 mm.

The extrusion pressure within the barrel is from 10 to 1000 psi and more particularly from 20 to 300 psi. There is progressive increase in pressure from the inlet towards the outlet of the barrel and it is very high in the frusto-conical pressure zone. Due to this very high pressure towards the outlet of the barrel, the pressure of injection of the coloured liquid must be maintained higher than this pressure, when injection happens at or near the outlet.

The barrel usually will include one rotatably mounted screw, but it is preferred that the barrel is partitioned lengthwise into a pair of compartments, where each compartment contains one screw. In this configuration, the screws rotate in counter- current manner, thereby conveying the extrudable mass into the frusto-conical pressure zone.

The temperature prevailing in the barrel should preferably be maintained under 70°C, and more preferably under 60°C.

This in some cases necessitates the cooling of the barrel, and for this purpose the barrel is provided with cooling jackets. Preferably the plodding is carried out with a billet temperature of 60°C to 80°C.

Preferably the screws have from 3 to 15 spirals, more preferably from 4 to 12 spirals, and most preferably 4 spirals. The number of spirals and the size (dimensions) of the screws can be adjusted to suit the scale of manufacture.

It is preferred that the injection means is located between the 2^nd and the 4^th spiral of the screw from the outlet end of the barrel. Preferably at least one pair of injection means is used, especially when the barrel is partitioned into two compartments and a screw is present in each. In this case, one means is disposed adjacent to a flight of each screw. In the present invention, a coloured liquid is injected into the compacted mass during its passage through the barrel. The injection is preferably made by means of one or more of a series of nozzles extending through the walls of the extruder barrel, each nozzle being provided with a stream of liquid by respective conduits and positive displacement pumps. The location of each nozzle can vary between the inlet end and outlet end of the barrel. It is preferred that a series of four nozzles is used when working with a single coloured liquid, to inject the additive at only a single point. Simultaneous injection through more than one nozzle can be used, especially when it is desired to inject more than one coloured liquid, e.g. the injection of different dye streams.

The nozzles project into the space between the barrel and the screws. For this reason, a clearance of from 2 to 5 mm is provided between the flight of the screws and the inner wall of the barrel so that the screws do not touch the wall of the barrel. The screw is preferably provided with a respective registering notch for each nozzle. In this case, the dye is injected close to the front end of the screws at a location corresponding approximately to the root diameter of the screws and at an angular position of 4 o'clock for the left screw and 10 o'clock for the right screw when facing the front end of the extruder. It is essential that the injection of coloured liquid happens at sufficiently high pressure so as to exceed pressure of extrudable detergent mass inside the barrel of extruder so that the colour can be injected without developing any backpressure on the picker pins, thereby clogging the pins. It is preferred that the pressure of injection of the coloured liquid is from 400 to 1200 psi. More preferably this pressure is between 500 and 1000 psi. The size of the picker pin opening can be varied as per requirement of colour injection, but it is preferred that it is from 0.2 to 20 mm, more preferably from 0.3 to 10 mm and most preferably it is 0.3 mm.

The type of coloured liquid to be injected is not critical, although it is preferred that the colouring matter is a non- bleeding dye or pigment, such as D & C Green dye No. 5. The pressure required to inject the colored liquid into the flowing stream of detergent mass also is critical and it should be greater than the pressure that is generated during extrusion in the barrel. The term "coloured liquid" herein refers to a fluent or fluid material, having colour contrast with a soap mass into which it is injected. The coloured liquid is preferably saponaceous solution e.g. of a dye or pigment but may also be a suspension or emulsion of pigment or dye in water, alcohol, glycerine or other liquid compatible with the detergent mass. It is preferred that the coloured liquid is a composition including 0.1 to 10 wt% dye, the balance being a polyol, such as glycerine. The preferred coloured liquid has a composition in percentages by weight, of water 9.5%, glycerine 83%, sodium carboxymethyl cellulose 1.5%, Monastral® Blue BVS Paste 2%, Ansteads® Green 11125 4%.

Where there are multiple points of injection of the coloured liquid, the dye solution fed into the middle area of the barrel serves principally for colouring the inner portions of the detergent. The amount of dye introduced at this point should amount to from 30% to 80% of the total quantity of dye that is to be used. The remaining dye solution is introduced into the detergent in the so-called "end area" which is located at the first to third screw spiral from the outlet end of the barrel. The end area is separated from the middle area by at least one, and preferably by 2 to 4 screw spirals. The dye solution introduced into the end area serves mainly for colouring the marginal portions of the detergent billets. The number of injection means located in this zone amounts preferably to from 2 to 6, although any desired number of such injection means can be used. The injection means can be spaced apart from one another as desired and distribution over the periphery of the barrel. It is preferred that the coloured liquid is injected in the direction of movement of the extrudable detergent composition as it reduces or prevents the clogging of the tip of the injection means that is in direct contact with the detergent mass.

Dyes commonly used in the soap industry can be used to colour the detergent mass. It is desirable to add thickening agents to the dye solutions in order to increase their viscosities. Suitable thickening agents are, for example, cellulose derivatives, such as cellulose glycolate or methyl cellulose, alginates, starch, hydrolyzed proteins, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylates, polyglycols and other polymers of natural or synthetic origin which can be dissolved in water or can be made to swell in water. For the production of pastel-toned marbling, generally from 10 to 40 g. of dye are needed per 100 Kg of detergent mass. Several times that amount i.e. from two to five times that amount is required to produce a brightly patterned detergent. It is also possible that different coloured solutions can be fed into the various areas and feeding means in order to achieve numerous attractive colour combinations and marbled pattern. Preferably, in order to obtain the desired contrast a relatively large volume of liquid will be injected.

It was observed by the present inventors that in the absence of the apertured plate, only a portion of the liquid was retained within the mass, while the remainder migrated to the surface of the mass as it was compressed and formed a substantially continuous layer on the surface.

This migration was mitigated by using the apertured plate, which allows for some desirable degree of mixing of the coloured liquid with the detergent mass. Over and above the use of apertured plate, It is preferred that the die-plate has a pair of slits, adjacent to each die to shave-off the outer 1 to 5 mm of the surface of the billet as it emerges from the nozzle, so as to reveal the marbled appearance below the surface of the billets.

It is preferred that the apertured plate has from about 5 to about 300 apertures, more preferably from 10 to 150 apertures. When a detergent mass is extruded through the apertures on each of the circular areas in the plate, bundles of rods are formed and as these bundles are compressed inwardly the coloured liquid injected through injection means is distributed substantially uniformly throughout the bundle. Passage of the extrudable detergent mass through this plate improves the quality of marbling and is crucial to ensure mixing of the coloured liquid with the detergent mass, else the colour tends to be concentrated only in one or more regions or locations within the billet that subsequently emerges from the nozzle.

While the apertures can assume any geometrical shape such as square, rectangular, oval or irregular shape, it is preferred that the apertures are circular, with the diameter being about

1 inch.

It is preferred that the apertured plate is 10 to 40 mm thick.

More preferably, thickness of the plate is 30 mm thick.

The penetration value of the extrudable detergent composition is preferably from 1.5 to 3 mm. It is preferred that the billet is cut into bars after it is split . It is preferred that the extrudable detergent composition includes from 10 to 40 wt% non-soap detergent active; 30 to 70 wt% inorganic particulate matter; 5 to 35 wt% water and from 0 to 70 wt% soap.

Further preferably, the composition includes 15 to 20 wt% non- soap detergent active, 40 to 50 wt% inorganic particulate matter and from 6 to 10 wt% water, and upto 25 wt% soap.

The non-soap detergent active

The actives are selected from non-soap actives that may be anionic, nonionic, cationic, zwitterionic or amphoteric in nature and it is particularly preferred that the soap level is upto 25% by weight of the composition, preferably it is less than 10% by weight and more preferably, the composition does not include any soap. The preferred anionic and specific detergent actives used in detergent bar technology are described in literature, for example in Surface Active Agents and Detergents, Volume II by 30 Schwartz, Perry and Berch (Interscience Publishers, N. Y. 1958) .

Specific examples of suitable anionic actives useful in this invention is non-soap actives selected from linear and branched alkyl benzene sulphonates, alkane sulphonates, secondary alcohol sulphates, primary alcohol sulphates, alpha olefin sulphonates, alkyl ether sulphates, fatty acyl ester sulphonates, alkyl carboxylates and mixtures of these. Especially preferred are compositions in which the anionic detergent active is linear alkyl benzene sulphonate (LAS) .

The term "total fatty matter", usually abbreviated to TFM is used to denote the percentage by weight of fatty acid and triglyceride residues present in soaps without taking into account the accompanying cations. For a soap having 18 carbon atoms, an accompanying sodium cation will generally amount to about 8% by weight. Other cations may be employed as desired for example zinc, potassium, magnesium, alkyl ammonium and aluminium. The term "soap" denotes salts of carboxylic fatty acids, more specifically alkali metal salts. The soap may be derived from any of the triglycerides conventionally used in soap manufacture-consequently the carboxylate anions in the soap may contain from 8 to 22 carbon atoms.

Builders

The detergency builders used in the formulation are preferably inorganic and suitable builders include, for example, alkali metal aluminosilicates (zeolites), alkali metal carbonate, sodium tripolyphosphate (STPP) , tetrasodium pyrophosphate (TSPP), citrates, sodium nitrilotriacetate (NTA) and combinations of these.

Builders are suitably used in an amount ranging from 0 to 30% by weight, preferably 10 to 20 % by weight.

Inorganic particulates

Inorganic particulate phase is an essential ingredient of the formulation and are incorporated especially for hard surface cleaning compositions. Preferably, the particulate phase includes a particulate structurant and/or abrasive, which is insoluble in water. Suitable inorganic particulates can be selected from, particulate zeolites, calcites, dolomites, feldspars, silicas, silicates, other carbonates, bicarbonates, borates, sulphates and polymeric materials such as polyethylene .

The most preferred inorganic particulates are calcium carbonate (as Calcite) , mixtures of calcium and magnesium carbonates (as dolomite) , sodium hydrogen carbonate, borax, sodium/potassium sulphate, zeolite, feldspars, talc, koalin and silica.

Calcite, talc, kaolin, feldspar and dolomite and mixtures thereof are particularly preferred due to their low cost and colour. Other conventional inorganic particulate structurants such as alumina silicate, boro-silicate structuring, boro- alumino silicate or calcium alumina silicate may be generated in situ or readily available forms can be incorporated. These are preferably included at 30 to 70 wt% and more preferably from 40 to 50 wt%.

Other additives

Other additives such as one or more water insoluble particulate materials such as polysaccharides such as starch or modified starches and celluloses may be incorporated.

Minor additives

Minor and conventional ingredients preferably selected from enzymes, antiredeposition agents, fluorescers, colour, preservatives and perfumes, also bleaches, bleach precursors, bleach stabilizers, sequestrants, soil release agents (usually polymers) and other polymers may optionally be incorporated up to 10 wt%.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of non-limiting examples only, with reference to the accompanying drawings in which: Figure 1 is a longitudinal section of the detergent extrusion apparatus according to one embodiment.

Figure 2 shows a plan view of the nozzle used in the apparatus of figure-1, when viewed from within the barrel.

Figure 3 shows the perspective view of a billet of detergent cut into two detergent bars .

Figure 4 shows marbled detergent bars according to the invention and an un-cut bar.

In all figures, like numerals represent like parts or components .

DETAILED DESCRIPTION OF THE FIGURES

In Figure 1 the extruder 1 is made up of the barrel 2 which has inlet 3 and outlet 4. Two screws 5 and 6 are rotatably mounted inside the barrel. A hopper 7 is provided near the inlet end of the barrel 2, through which extrudable detergent composition is fed into the barrel. Temperature inside the barrel is controlled by circulating coolant through cooling jackets 8 and 9. There is space 12 between the outlet of the barrel 4 and the apertured plate 10. Picker pins 13 and 14, act as the means for injecting liquid colour into the mass as it is extruded. The frusto-conical pressure zone 11 terminates into a nozzle 15. This nozzle has a die plate 16 which has dies with profiles corresponding to the desired profile of the extruded billet.

In use, extrudable detergent mass in the form of dough is fed through the hopper 7 into the barrel 2. Screws 5 and 6 rotating within the barrel help to mix the dough and convey it forward in the direction of the apertured plate 10. Each screw has respective axis 5' -5" and 6' -6". The screws 5 and 6 are connected to an external driving assembly (not shown) with the help of which they rotate in a counter-current manner. As the mass is conveyed, coloured liquid having a visual appearance differing from the detergent mass is injected through picker pins 13 and 14. These pins are in communication with a source of liquid and a compressor which pressurizes the liquid, (source and compressor not shown) . When the detergent mass passes through the plate 10, it is extruded in the form of noodles .

Thereafter, it enters the frusto-conical pressure zone 11 where it undergoes compression due to the positive conveying action of the screws and the back-pressure generated due to the progressively decreasing cross-sectional area of the zone 11. The mass then passes through die plate 16 fitted inside the nozzle 15, through which it emerges in the form of a billet. As the billet emerges from the nozzle, it gets split into two halves and each half passes through the respective die, whereafter, it emerges from the die on the opposite side, assuming the profiles of the dies. The cutting edge in the nozzle 15 splits the billet parallel to the axis of the screws 5 and 6 and in the plane of extrusion. After the detergent mass is extruded in the form of a billet and after the billet has been split into two halves, a cutter blade or blades, operating co-incidentally, (not shown) positioned ahead of the nozzle can cut the split billet into bars of desired shape and size .

Figure 2 shows the plan view of the die-plate 16, when viewed from within the barrel, which shows nuts 17 and 18 which are used to connect this plate 16 to the nozzle. The die-plate 16 has two dies 19 and 20 which are mirror images of each other and have profiles corresponding to the desired profile of the detergent bars. At the intersection of the dies 19 and 20 there is a cutting edge 21 of the blade which helps to split the billet into two halves as it emerges from the nozzle. In addition to the cutting edges, the dies 19 and 20 also have respective slits 22 and 23, which help to shave-off the outer 1-5 mm of the billet as it is extruded.

Figure 3 shows a billet cut into two detergent bars 24 and 25. They have been shown in a bottom perspective view. Figure-4 shows marbled detergent bars according to the invention and an un-cut bar.

The inventive process will now be described further with the help of the following non-limiting examples.

Examples

The following raw materials were used to make non-soap detergent bars in an approximately 20 Kg batch size.

Table-1

Perfume 0.02

Colour (Liquid RED ST from Milliken Corp, USA) 0.1 (10% solution in glycerine)

Total 20.42

Example 1

Soda ash was charged into a sigma-mixer, followed by addition of LAS acid. This neutralizes the acid. Water was then added to this mixture to facilitate neutralisation.

Thereafter, aluminium sulphate, sodium tripolyphosphate, 6.64 Kg calcite, alkaline silicate, HA-20, 4 Kg of calcite and perfume were added in sequence. The materials were mixed for 5- 7 minutes to get white dough.

This dough was fed into an extruder having two screws, each having 4 screw threads, through the hopper. The coloured liquid was injected into the dough under pressure of 500 psi, through a pair of picker pins disposed near the flight of each screw and close to the 2^nd screw from the apertured plate, along the direction of extrusion. A billet of detergent was extruded through the nozzle, and the same was split into two, as it was extruded. The split billets were further cut into bars with a cutting blade. The resulting bars showed marbled appearance on the entire surface.

Comparative Example 2

For comparative analysis, the coloured liquid was added to the dough through the hopper. The extruded billet was cut into bars. The resulting bars showed that the colour had substantially blended with the dough and no marbled appearance could be seen. Comparative Example 3

In this experiment, the coloured liquid was injected through conduits in the apertured plate. In this case, the colour did not blend at all with the dough and it could be seen as concentrated spots within the billet. No marbled appearance was visible .

Although the invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms .

Claims

1. A process for making a shaped marbled non-soap detergent bar, comprising the steps of:

(a) feeding an extrudable non-soap detergent composition into an extruder comprising at least one screw rotatably mounted within a barrel having inlet and outlet , where rotation of said screw conveys said composition from the outlet into a frusto-conically converging pressure zone, which converges into at least one nozzle from which a billet of extruded detergent emerges; and an apertured plate interspersed between said outlet and said pressure zone;

(b) injecting a coloured liquid into said composition through an injection means, located upstream of said apertured plate, the pressure of injection being higher than that generated within the extruder, characterized in that, said billet is split once parallel to the axis of said screw, by a splitting means, as it is extruded from said nozzle, so as to provide marbling on the billet.

2. A process as claimed in claim 1 , wherein the extrusion pressure in said barrel is from 10 to 1000 psi, preferably from 20 to 300 psi.

3. A process as claimed in claim 1 or claim 2, wherein the penetration value of said extrudable detergent composition is from 1.5 to 3 mm.

4. A process as claimed in any one of the preceding claims wherein said composition comprises 10 to 40 wt% non-soap detergent active; 30 to 70 wt% inorganic particulate matter; 5 to 35 wt% water and from 0 to 70 wt% soap.

5. A process as claimed in any one of the preceding claims wherein said coloured liquid is a composition comprising 0.1 to 10 wt% dye, the balance being a polyol.

6. A shaped solid marbled non-soap detergent obtainable by a process as claimed in any one of the preceding claims.

7. An apparatus for making a shaped marbled non-soap detergent bar by a process as claimed in any one of the preceding claims 1 to 5, comprising an extruder comprising:

(i) .a barrel having inlet and outlet, within which at least one screw is rotatably mounted,

(ii).a frusto-conically converging pressure zone; which is in fluid communication with the outlet of said barrel, said zone having at least one nozzle;

(iii) . an apertured plate interspersed between said outlet and said pressure zone;

(iv) . means for injecting a colored liquid into said composition, located upstream of said apertured plate; and

(v) . means for splitting said billet, parallel to the axis of said screw.

8. An apparatus as claimed in claim 7, wherein said means for splitting is a die-plate having a pair of dies, with a blade having a cutting edge, disposed there between, said cutting edge being oriented parallel to the axis of the screw.

9. An apparatus as claimed in claim 7 or 8, wherein the distance between the outlet of said barrel and the apertured plate is from 5 to 500 mm, preferably from 250 to 350 mm.

10. An apparatus as claimed in any one of the preceding claims 7 to 9, wherein said injection means is located between the 2^nd and 4^th thread of said screw from the outlet end of said barrel .

11. An apparatus as claimed in any one of the preceding claims 7 to 10, wherein said die-plate has a pair of slits, adjacent to each die to shave-off the outer 1 to 5 mm of the surface of the billet as it is extruded from the nozzle.

12. An apparatus as claimed in any one of the preceding claims 7 to 11, wherein said barrel is partitioned lengthwise into a pair of compartments, each said compartment including a screw.

13. An apparatus as claimed in any one of the preceding claims 7 to 12, comprising at least one pair of said injection means.

14. An apparatus as claimed in any one of the preceding claims 7 to 13, wherein said apertured plate has from 5 to about 300 apertures .

15. An apparatus as claimed in claim 13, wherein said injection means is a pair of picker pins, which are in fluid communication with a source of said coloured liquid.