EP0090648B1

EP0090648B1 - Detergent processing

Info

Publication number: EP0090648B1
Application number: EP83301766A
Authority: EP
Inventors: Terence Allan Clarke; Richard Barrie Edwards; Graeme Neil Irving
Original assignee: Unilever NV
Current assignee: Unilever NV
Priority date: 1982-03-29
Filing date: 1983-03-29
Publication date: 1986-06-04
Also published as: BR8301601A; CA1209437A; JPS58208398A; GB2118058B; EP0090648A1; MY8700908A; GB8308633D0; JPS6131752B2; GB2118058A; DE3363897D1

Description

Field of the Invention

This invention relates to the processing of detergent feedstocks. The processed feedstocks can be made into bars containing entrained gases. These bars are usually referred to as aerated bars.

Background to the Invention

The presence of entrained gas in a detergent bar reduces the bulk density of a product and thus allows it to float in the washing solution if sufficient gas is incorporated. The gas, which is usually air but may be nitrogen, carbon dioxide or other gas amenable to dispersal throughout the detergent, is introduced into the detergent material in finely dispersed form to provide a product which appears to have uniform structure when viewed by the user.

General Description

The present invention uses a device of the cavity transfer mixer class to introduce gas into the detergent material. These devices comprise two closely spaced mutually displaceable surfaces each having a pattern of cavities which overlap during movement of the surfaces so that material moved between the surfaces traces a path through cavities alternately in each surface so that the bulk of the material passes through the shear zone generated in the material by displacement of the surfaces.
Cavity transfer mixers are normally prepared with a cylindrical geometry and in the preferred devices for this process the cavities are arranged to give constantly available but changing path ways through the device during mutual movement of the two surfaces. The devices having a cylindrical geometry can comprise a stator within which is journalled a rotor; the opposing faces of the stator and rotor carry the cavities through which the material passes during its passage through the device.
The device may also have a planar geometry in which opposed plane surfaces having patterns of cavities would be moved mutually, for example by rotation of one plane, so that material introduced between the surfaces at the point of rotation would move outwards and travel alternately between cavities on each surface.
Another form of cylindrical geometry maintains the inner cylinder stationary while rotating the outer cylinder. The central stator is more easily cooled, or heated if required, because the fluid connections can be made in a simple manner; the external rotor can also be cooled or heated in a simple manner. It is also mechanically simpler to apply rotational energy to the external body rather than the internal cylinder. Thus this configuration has advantages in construction and use.
Material is forced through the mixer using auxiliary equipment as the rotor is turned. Examples of the auxiliary equipment are screw extruders and piston rams. The auxiliary equipment is preferably operated separately from the mixer so that the throughput and work performed on it can be separately varied. The separate operation may be carried out by arranging the auxiliary equipment to provide material for processing at an angle to the centre line of the shear- producing device. This arrangement allows rotational energy to be supplied to the device producing shear around its centre line. An in-line arrangement is more easily achieved when the external member of the device is the rotor. Separate operation of the device and auxiliary equipment assists in providing control of the processing.
In general a variety of cavity shapes can be used, for example Metal Box (GB-A-930 339) disclose longitudinal slots in the two surfaces. The stator and rotor may carry slots, for example six to twelve, spaced around their periphery and extending along their whole length.
EPA 0048590 describes a specific form of cavity transfer mixer and suggests its application in soap processing.
There are six applications directed to detergent processing copending with the present applications. EPA 0090644 (83301762.7) describes the processing of superfatted soap formulation to improve the properties. EPA 0090645 (83301763.5) describes the processing of a physically soft soap feedstock to provide a hardened product. EPA 0090646 (83301764.3) describes the processing of soap compositions to reduce gritti- ness. EPA 0090647 (83301765.0) describes the incorporation of a volatile component in a soap composition.
EPA 0090649 (83301767.6) describes the manufacture of a transparent soap composition and EPA 0090650 (83301768.4) describes the control of phases in soap containing compositions.
Preferably one or both surfaces are subjected to thermal control. The process allows efficient heating/cooling of the materials to be achieved.
The detergent feedstock may contain non-soap detergents. Examples of these actives are alkane sulphonates, alcohol sulphates, alkyl benzene sulphonates, alkyl sulphates, acyl isethionates, olefin sulphonates and ethoxylated alcohols. These non soap detergents may be the major proportion or, in some formulations, the whole of the detergent content.
The processed feedstock was made into bar form using standard stamping machinery. Other product forms, e.g. extruded particles (noodles) and beads can be prepared from the feedstock. The process of the invention provides efficient dispersal of the gas throughout the detergent. The gas may be introduced as a component or may be formed in situ by a chemical reaction controlled by injection of a reactant. The incorporation of the gas will usually be dependant on the temperature and composition of the detergent.
The gas may be incorporated in the auxiliary equipment or the cavity transfer mixer.
Examples of points at which gas can be incorporated are the input hopper of the auxiliary equipment, injection points in a screw plodder and by direct injection into a cavity, or cavities, in the cavity transfer mixer.

Drawings

The invention will be described with reference to the accompanying diagrammatic drawings in which:

Figure 1 is a longitudinal section of a cavity transfer mixer with cylindrical geometry;
Figure 2 is a transverse section along the line II-II on Figure 1;
Figure 3 illustrates the pattern of cavities in the device of Figure 1;
Figures 4, 5 and 7 illustrate other patterns of cavities;
Figure 6 is a transverse section through a mixer having grooves in the opposed surfaces of the device;
Figure 8 is a longitudinal section of a cavity transfer mixer in which the external cylinder forms the rotor.

Specific Description of Devices

Embodiments of the devices will now be described.
A cavity transfer mixer is shown in Figure 1 in longitudinal section. This comprises a hollow cylindrical stator member 1, a cylindrical rotor member 2 journalled for rotation within the stator with a sliding fit, the facing cylindrical surfaces of the rotor and stator carrying respective pluralities of parallel, circumferentially extending rows of cavities which are disposed with:

a) the cavities in adjacent rows on the stator circumferentially offset;
b) the cavities in adjacent rows on the rotor circumferentially offset; and
c) the rows of cavities on the stator and rotor axially offset.

The pattern of cavities carried on the stator 3 and rotor 4 are illustrated on Figure 3. The cavities 3 on the stator are shown hatched. The overlap between patterns of cavities 3, 4 is also shown in Figure 2. A liquid jacket 1A is provided for the application of temperature control by the passage of heating or cooling water. A temperature control conduit 2A is provided in the rotor.
The material passing through the device moves through the cavities alternately on the opposing faces of the stator and rotor. The cavities immediately behind those shown in section are indicated by dotted profiles on Figure 1 to allow the repeating pattern to be seen.
The material flow is divided between pairs of adjacent cavities on the same rotor or stator face because of the overlapping position of the cavity on the opposite stator or rotor face.
The whole or bulk of the material flow is subjected to considerable working during its passage through the shear zone generated by the mutual displacement of the stator and rotor surfaces. The material is entrained for a short period in each cavity during passage and thus one of its velocity components is altered.
The mixer had a rotor radius of 2.54 cm with 36 hemispherical cavities (radius 0.9 cm) arranged in six rows of six cavities. The internal surface of the stator carried seven rows of six cavities to provide cavity overlap at the entry and exit. The material to be worked was injected into the device through channel 5, which communicates with the annular space between the rotor and stator, during operation by a screw extruder. The material left the device through nozzle 6.
Figure 4 shows elongate cavities arranged in a square pattern; these cavities have the sectional profile of Figure 2. These cavities are aligned with their longitudinal axis parallel to the longitudinal axis of the device and the direction of movement of material through the device; the latter is indicated by the arrow.
Figure 5 shows a pattern of cavities having the dimensions and profile of those shown in Figures 1, and 3. The cavities of Figure 5 are arranged in a square pattern with each cavity being closely spaced from four adjacent cavities on the same surface. This pattern does not provide as high a degree of overlap as given by the pattern of Figure 3. The latter has each cavity closely spaced to six cavities on the same surface, i.e. a hexagonal pattern.
Figure 6 is a section of a cavity transfer mixer having a rotor 7 rotatably positioned within the hollow stator 8 having an effective length of 10.7 cm and a diameter of 2.54 cm. The rotor carried five parallel grooves 9 of semi-circular cross section (diameter 5 mm) equally spaced around the periphery and extending parallel to the longitudinal axis along the length of the rotor. The inner cylindrical surface of the stator 8 carried eight grooves 10 of similar dimensions extending along its length and parallel to the longitudinal axis. This embodiment, utilised cavities extending along the length of the stator and rotor without interruption. Temperature control jacket and conduit were present.
Figure 7 shows a pattern of cavities wherein the cavities on the rotor, shown hatched, and stator have a larger dimension normal to the material flow; the latter is indicated by an arrow. The cavities are thus elongate. This embodiment provides a lower pressure drop over its length compared with devices of similar geometry but not having cavities positioned with a longer dimension normal, i.e. perpendicular to the material flow. To obtain a reduction in pressure drop at least one of the surfaces must carry elongate cavities having their longer dimension normal to the material flow.
The cavity transfer mixer of Figure 8 had the external cylinder 11 journalled for rotation about the central shaft 12. Temperature control jacket 13 and conduit were present but the latter is not shown because the cavities on the central shaft are shown in plan view while the rotor is sectioned. The central stator (diameter 52 mm) had three rows 14 of three cavities with partial, i.e. half cavities at the entry and exit points. On the rotor there were four rows 15 of three cavities. The cavities on the stator and rotor were elongate with a total arc dimension of 5.1 cm normal to the material flow with hemispherical sections ends of 1.2 cm radius joined by a semicircular sectioned panel of the same radius. The cavities were arranged in the pattern of Figure 7, i.e. with their long dimension normal to material flow. The rotor was driven by a chain drive to external toothed wheel 16.

Example

A cavity transfer mixer illustrated in Figure 1 was used.
The mixer had a rotor radius of 2.54 cm with 36 hemispherical cavities (radius 0.9 cm) arranged in six rows of six cavities. The internal surface of the stator carried seven rows of six cavities to provide cavity overlap at the entry and exit.
A soap feedstock derived from tallow (60%) and coconut oil (40%) in which 7.5% was present as free fatty acids; was vacuum dried to 10% moisture and 0.6% electrolyte. The dried material in chip form was extruded through a standard soap plodder which did not apply a vacuum to the feed chamber. Air was thereby incorporated in the material as coarse bubbles. The material then passed into the cavity transfer mixer as the rotor was rotated at 120 rotations per minute. The soap temperature at the mixer inlet was 38°C and it left the mixer at 55°C; the throughput was 500 g min-^1. Water cooling was applied to the rotor and starter. The extruded billet presented an even appearance and had a reduced density.

Claims

1. The process of aerating detergent material in which detergent material in admixture with gas is subjected to working by passing the material between two closely spaced mutually displaceable surfaces each having a pattern of cavities which overlap during movement of the surfaces so that the material moved between the surfaces traces a path through cavities alternately in each surface, whereby the bulk of the material passes through the shear zone generated in the material by displacement of the surfaces.

2. A process according to Claim 1 wherein the two surfaces have cylindrical geometry.

3. A process according to Claim 1 or 2 wherein thermal control is applied to at least one surface.

4. A process according to any preceding claim wherein the cavities in at least one surface are elongate with their long dimension normal to the flow of material.