AU2004222849A1 - Method for producing a cleansing tablet - Google Patents

Description

.7 P/00/01 1 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention tide: Method for producing a cleansig tablet The following statement is a full description of this invention, including the best method of performing it known to us: mcmM l 1013685101304652993 4.04.2000 1

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Method for producing a cleansing tablet Field of the invention The present invention relates to a method for producing a cleansing tablet. In particular the present invention relates to a method for producing a cleansing tablet that allows a gel material to be added to the cleansing tablet in a controlled manner.

00 C Background of the invention In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date: part of common general knowledge; or (ii) known to be relevant to an attempt to solve any problem with which this specification is concerned.

Consumers rely on cleansing or freshening products for a variety of applications. For example, cleansing products are known for use in the laundry for clothes washing and bleaching or stain pre-treatment, in the kitchen for dishwashing, in the bathroom for personal care applications such as bathing, and for general household applications such as floor cleaning. These cleansing products are usually available in the form of a liquid, solid or flowable particles and are readily available at commercial outlets such as supermarkets.

Cleansing tablets have several advantages over particulate or liquid detergent compositions. In particular, from the perspective of the consumer, cleansing tablets provide a consistent standard dosage of active detergent components, substantially reduce the likelihood of spillage or exposure to the active ingredients of the tablet, and are generally more convenient to use than powders or liquids. From the perspective of the formulator, cleansing tablets have the advantage of enabling the use of technologies that would otherwise cause problems in a powder or liquid form. For example, multilayer tablets enable incompatible materials to be isolated from each other.

Cleansing tablets are commonly prepared by compressing powder or granular materials often incorporating more than one layer of materials (typically distinguishable by colour). However, some components are not suitable for inclusion in a tablet.

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For example, some active ingredients of cleansing processes are not well suited to incorporation into a cleansing tablet because the manufacturing process of the tablet may U have an adverse effect on the active ingredient.

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Some such components are adversely affected by the pressures used. to form the (Ni tablets, becoming unstable or inactive as a result of compression. One example is that of encapsulated enzymes which, if crushed, release potentially harmful enzyme dust. Hence O encapsulated enzymes require special precautions during manufacture have not owing to (Ni the compressive forces applied during the manufacturing process pose a risk of crushing the encapsulated enzymes.

O 10 Other components (such as many surfactants) have undesirable effects in tablet (Ni formulations such as excessive binding, stickiness or undesirable friability leading to inferior quality tablets.

Some combinations of components are also incompatible and when they are in close proximity in a tablet they can interact leading to loss of activity, formation of undesirable by-products, changes in aesthetics (appearance and odour) or disintegration of the tablet structure.

One solution to this problem has been to separate certain cleansing tablet components into different areas within the tablet. These areas may contain a region made using a different process or technology to the rest of the tablet. For example, multi-layer compressed cleansing tablets are well known in the technology, each layer comprising a zone in which different components are located. The different layers are often held together by soluble adhesive, or alternatively compression of the layers together may cause the layers to bind.

Multiple layer tablets, are commonly prepared using multiple compression steps.

The compression force may be varied in accordance with the nature and number of layers.

In general terms there is an inverse relationship between the rate at which the tablet dissolves and the compression force used to form the tablet.

If the compression force is not optimal problems may arise such as insufficient dissolution of regions of a tablet, particularly in shorter or lower temperature wash cycles of a dishwasher or clothes washing machine. If a single compression step is used to compress several layers at the same time other problems may arise because the optimum compression for each layer may be different. This may lead to one layer being soft and friable while another regions of the tablet is hard and slow to dissolve.

arsm M0111598591vl 305412057 Other methods are known for separating detergent components into different parts of a tablet. EP-0,224,135 describes a cleansing tablet for use in a dishwasher, the 0 tablet comprising a warm water soluble melt into which is pressed a cold water soluble 0 V tablet. One part of the tablet dissolves in the pre-rinse cycle, and the other part dissolves 5 in the main wash cycle of the dishwasher.

SUS 6,451,754 describes a process for preparing a detergent tablet where a non- 00 compressed portion containing an otherwise tablet-incompatible material such as an enzyme, is delivered to a pre-formed compressed portion, thereby allowing incorporation of the enzyme into the tablet body. The non-compressed portion is then coated with a water-soluble coating layer that becomes solid within about 60 seconds of contacting the non-compressed portion, Suitable materials for the coating layer are materials selected from the group consisting of fatty acids, alcohols, diols, esters and ethers, adipic acid, carboxylic acid, dicarboxylic acid, polyvinyl acetate (PVA), polyvinyl pyrrolidone (PVP), polyacetic acid (PLA), polyethylene glycol (PEG) and mixtures thereof.

Although this process allows otherwise incompatible materials to be incorporated into cleansing tablets, it has led to a further problem that those materials are easily displaced from their site of application on the tablet when coating layer is added. In particular, when the materials are added to a cavity formed in the tablet body, the addition of the liquid coating layer causes the materials to be spilled out of the cavity.

It would thus be advantageous to provide a method for forming a cleansing tablet that allows a coating layer to be added to a tablet body in a controlled manner to minimise this displacement.

Summary of the invention According to a first aspect of the present invention there is provided a method for producing a cleansing tablet, the method comprising the steps of: forming at least one tablet layer; applying at least one active or beneficial ingredient to the layer; providing a damper and adding a gel material to the active or beneficial ingredient in a manner such that gel material impacts the damper, to at least partially absorb the kinetic energy of the gel material, immediately prior to contacting the active or beneficial ingredient.

arsm MO 111598591vl 305412057 The damper preferably takes the form of a landing, step or ledge. The damper may be located on the equipment used to add the gel material to the active or beneficial o ingredient.

0 t In one particularly preferred arrangement the damper comprises a ledge formed in the tablet layer. The ledge is preferably positioned and shaped such that the ledge projects above the applied active or beneficial ingredient.

0- 00 In this arrangement the material may be added to the tablet layer in a controlled

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manner so as to contact the ledge wherein the material's kinetic energy is partly absorbed prior to contacting the active or beneficial ingredient. By adding the gel material via the S10 damper the gel material may be added in a controlled manner to minimise disturbance of (Ni the active or beneficial ingredient.

Preferably the method further includes the steps of forming a cavity in the tablet layer and applying the active or beneficial ingredient to the layer by placing the ingredient into the cavity. In this arrangement the damper may comprise a ledge located to extend into the cavity above the active or beneficial ingredient. The gel material may be added to the tablet layer by first contacting the ledge and then flowing into the cavity to mix with and/or cover the beneficial or active ingredient. The gel material may also cover the ledge in the completed tablet.

The damper may extend into the cavity from an internal wall of the cavity, and may be substantially horizontal or angled downwardly and inwardly into the cavity.

In another embodiment according to the present invention the damper is operatively connected to the apparatus used to apply the gel material so that the damper is located above the active or beneficial ingredient when the material is added, the material being added to the tablet layer by first contacting the damper, wherein the material's kinetic energy is partly absorbed.

The method provided by the present invention may further include the step of heating the top surface of the tablet layer prior to applying the gel material, thereby minimising the tendency of the gel material to extract granules from the tablet layer upon cooling of the tablet layer.

The method may also include the step of heating the tablet after applying the gel material, wherein a portion of the gel material melts andthen resets to form a smoother finish for the tablet.

arsm MO111598591v1 305412057 The term "gel material" is used herein to mean a gel or gel-like material and may include a gel-like material sometimes known in the art as a "melt".

O The present invention provides in another embodiment a method for producing a cleansing tablet, wherein the gel material comprises a clear or translucent gel which (-i permits the active or beneficial ingredient to be visible in the formed cleansing tablet.

The present invention provides in another embodiment a method for producing a 00 cleansing tablet, the method comprising the steps of: (-i (N forming at least one tablet layer having a cavity or depression therein, applying at least one active or beneficial ingredient to the cavity or depression, and adding a gel material to the active or beneficial ingredient in a manner which permits the ingredient to be visible, whereby to form a cleansing tablet.

The present invention provides in another embodiment a method for producing a cleansing tablet, the method comprising the steps of: forming at least one tablet layer having a cavity or depression therein, applying at least one active or beneficial ingredient to the cavity or depression, and adding a clear or translucent gel or gel-like material to the active or beneficial ingredient in a manner which permits the ingredient to be visible, whereby to form a cleansing tablet.

Step of the above embodiments may precede step The present invention further provides a cleansing tablet produced in accordance with methods according to the invention as described herein.

The present invention provides in another embodiment a cleansing tablet having at least one tablet layer and at least one active or beneficial ingredient applied to the tablet layer, and a gel or gel-like material applied to the ingredient.

The present invention provides in another embodiment a cleansing tablet having at least one tablet layer and at least one active or beneficial ingredient applied to the arsm M0111598591vl 305412057 tablet layer, and a clear or translucent gel or gel-like material applied to the ingredient in a manner which permits the active ingredient to be visible.

O The active or beneficial ingredient may be fully or partly visible through the gel or ti gel-like material. Where the ingredient is visible through the gel or gel-like material, the (Ni presence or absence of the active ingredient can be readily determined by visual inspection.

0- 00 In the context of the present invention the term "tablet" is also intended to include (Ni bars, sticks and other cleansing or freshening agent delivery forms known in the art for c-i personal care and not limited to such delivery forms for dishwashing or clothes washing machines.

(Ni A tablet layer will typically form part of the main body of the tablet. A tablet layer may be substantially planar so that the ingredient is applied to a surface or a face of that layer. A tablet layer may in one embodiment include a cavity, into which part or all of the ingredient may be deposited. A tablet layer may include a cavity on more than one face to enable the application of active ingredient to the cavity of each face of the tablet layer.

A main body of the cleansing tablet will typically be formed from a compressed material such as is known in the art. The compressed material may be a cleansing agent or a plurality of cleansing agents as is known in the art, or it may be another material such as a bath salt. Other cleansing tablet materials are envisaged within the scope of the invention.

The active or beneficial ingredient may be delivered or deliverable to the tablet layer in any suitable form. Suitable forms include liquid, powder or granular form. It may comprise a bead in which the active or beneficial ingredient is encapsulated. Examples of suitable encapsulated active ingredients include encapsulated enzymes. Encapsulated enzymes have hitherto been difficult to incorporate into cleansing tablets as they have been observed to be adversely affected by abrading or crushing during a tablet pressing operation. Methods according to the present invention are thought to improve or preserve the activity of the enzymes when introduced into a tablet in the form envisaged by the invention.

Other examples of suitable active or beneficial ingredients include encapsulated and non-encapsulated oils such as a bath oil or an oil containing a vitamin, encapsulated and non-encapsulated creams such as a vitamin E cream, encapsulated and nonencapsulated scents such as a perfume. In these embodiments layers of two different gels or gel like materials may be used. Further examples of suitable active or beneficial arsm M0111598591vl 305412057 ingredients include encapsulated and non-encapsulated botanical products such as dried petals or whole flowers. Other active or beneficial ingredients for use in cleansing tablets O according to the invention are envisaged within the scope of the present invention. The tA bead material used for encapsulating an active ingredient will typically be degradable or capable of rupture in response to exposure to a stimulus such as water or heat.

It is also envisaged that active or beneficial ingredient(s) having a purely aesthetic 0or decorative effect may be incorporated into tablets according to methods of the 00 invention.

(Ni The gel material will preferably be in the form of a soft solid or a solidified liquid at ambient temperatures. It is particularly preferred that the gel material is solid or a t\ pseudo-plastic gel that remains substantially static in the absence of force.

It is particularly envisaged that the gel material has sufficient fluidity when heated to enable application to the active ingredient, and to have a solid or pseudo-plastic consistency following production and return to ambient temperatures.

The gel material preferably forms a seal with the tablet layer so that no, or no substantial, migration of active ingredient away from the site of its application occurs.

The gel material may be added to the active or beneficial ingredient in any suitable manner. The gel material is applied by means of at least one nozzle at elevated temperatures. Where the active or beneficial ingredient is in a mobile form such as powder or granules, rapid application of the gel directly onto the ingredient may result in unwanted displacement of, or disruption to, the ingredient. Where the tablet layer includes a cavity into which active or beneficial ingredient is to be placed, the gel materialdelivery nozzle is preferably oriented such that the gel is applied near the edges of the cavity and away from the ingredient, wherein displacement of the ingredient by the application of the gel is minimised. Due to the relative fluidity of the gel material when heated, the gel material is able to migrate from the edges of the cavity and to mingle or mix with, encapsulate, entrain, cover, coat or otherwise bond to the ingredient.

In another embodiment the gel material may be applied to the granules or powder of active or beneficial ingredient relatively slowly so that displacement of or disruption to the active ingredient is minimised. In this embodiment the gel material may also mingle, coalesce or mix with, encapsulate, entrain, cover, coat or otherwise bond to the active ingredient.

The gel material is typically substantially soluble in water and/or capable of dissolving when exposed to elevated temperatures, so as to facilitate the release of the arsm M0111598591vl 305412057 active ingredient(s) into an environment such as a dishwashing water, a clothes washing water or into a bath water.

o The tablet layer and the gel material preferably have bonding characteristics to t' enable the gel-like material and the tablet layer to be held together for transport, storage

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and handling in order to maintain the integrity of the tablet during those phases of its life cycle.

00 Brief description of preferred embodiment (N The invention will now be further explained and illustrated by reference to the accompanying drawings in which: 10 Figure 1 is a cross-sectional view of a cleansing tablet to which an active ingredient has been added according to one form of the method of the invention; and Figure 2 is a side view illustrating the step of adding the active or beneficial ingredient to a cleansing tablet by use of a nozzle arrangement and damper according to one form of the method of the invention; and Figure 3 is a side view illustrating an alternative arrangement for providing the damper.

Turning to Figure 1, a cleansing tablet 10 is shown having upper and lower layers and a cavity or depression 12 in the upper layer, into which an active or beneficial ingredient 14 has been added by carrying out the method of the present invention. A gel material 16 has also been added to the cleansing tablet to mingle, cover, coalesce with or coat the active or beneficial ingredient.

In the embodimentshown the gel material 16 substantially fills the cavity 12.

Because the active or beneficial ingredient 14 and the gel material 16 have been added to a preformed cleansing tablet 10, they are not subject.to the compressive and other forces and temperatures associated with the manufacturing process of the cleansing tablet.

Figure 2 illustrates a nozzle 20 for adding the gel material 16 to the cleansing tablet 10 so as to cover, coat, mingle or mix with the active ingredient 14 that has already been added to the cleansing tablet 10. A horizontal platform 15 is integrally formed with the tablet layer extends out from the cavity wall and into the cavity. The level of the platform is above that of the active ingredient 12.

When the gel material is added to the preformed tablet layer its first point of contact with the tablet is with the platform owing to it being at a higher level than the arsm M0111598591vl 305412057 active or beneficial ingredient. This has the effect of the platform 12 effectively reducing the kinetic energy of the gel material that could otherwise cause the active or beneficial 0 ingredient to splash up out of the cavity 16. Instead, the gel material flows in a controlled V) manner into the cavity to coat the active or beneficial ingredient.

Some gel materials used to fill the cavity 16 contract during cooling from process temperatures and can pull some of the tablet granules away from the tablet. One possible solution to this problem is to operate at a lower temperature. This however is not 00 possible for some gel materials. Somewhat surprisingly if the top surface of the tablet C1 layer prior is heated prior to applying the gel material, the tendency of the gel material to C 10 extract granules from the tablet layer upon cooling of the tablet layer is minimised..

Some gel materials used to fill the cavity 16 also contract during cooling from process temperatures, leading to cracking or an uneven textured surface of the cooled gel material. Such a surface is less visually appealing than a smooth surface. To overcome this problem, the tablet may be heated after applying the gel material, wherein a portion of the gel material melts and then resets to form a smoother finish for the tablet.

An alternative arrangement is illustrated in Figure 2 where the platform 15 is provided as part of the nozzle apparatus 20 through which the gel is added to the cavity of the cleansing tablet.

The word 'comprising' and forms of the word 'comprising' as used in this description does not limit the invention claimed to exclude any variants or additions.

Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention.

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Claims (14)

1. A method for producing a cleansing tablet, the method comprising the steps of: 0 forming at least one tablet layer; c applying at least one active or beneficial ingredient to the layer; and C 5 providing a damper and adding a gel material to the active or beneficial 00 ingredient in a manner such that gel material impacts the damper, to at least C partially absorb the kinetic energy of the gel material, immediately prior to contacting the active or beneficial ingredient.

2. A method according to claim 1 wherein the damper takes the form of a landing, step or ledge.

3 A method according to claim 2 wherein the damper is located on the equipment used to add the gel material to the active or beneficial ingredient.

4. A method according to claim 2 wherein the damper comprises a ledge formed in the tablet layer, the ledge positioned and shaped such that the ledge projects above the applied active or beneficial ingredient.

A method according to one of claims 1 to 4 further including the step of forming a cavity in the tablet layer and applying the active or beneficial ingredient to the layer by placing the ingredient into the cavity.

6. A method according to claim 5 wherein the damper extends into the cavity from an internal wall of the cavity, and is substantially horizontal or angled downwardly and inwardly into the cavity.

7. A method according to any one of claims 1 to 6 wherein the gel material has sufficient fluidity when heated to enable application to the tablet body, and to have a solid or pseudo-plastic consistency following production and return to ambient temperatures.

8. A method according to any one of claims 1 to 7 wherein the gel material forms a seal with the tablet layer so there is no, or no substantial migration of active ingredient away from its site of application to the tablet layer.

9. A method according to any one of claims 1 to 6 wherein the gel material is substantially soluble in water and/or capable of dissolving when exposed to elevated temperatures, so as to facilitate the release of the active or beneficial arsm M0111598591vl 305412057 ^1- ingredients into an environment such as dishwashing water, clothes washing water or bath water.

S i10. A method according to claim 9 wherein the gel material is a water soluble waxy l t material such as PEG 4000.

11. A method according to claim 9 wherein the gel material is a blend of a solvent such as PEG 1500 and a gelling agent such as Teric PE68 or Teric PE87. 00

12. A method according to any one of claims 1 to 11 wherein the gel material is clear or translucent, wherein the active or beneficial ingredient is fully or partially visible O through the gel material.

13. A method according to any one of claims 1 to 12 further include the step of heating the top surface of the tablet layer prior to applying the gel material, thereby minimising the tendency of the gel material to extract granules from, the tablet layer upon cooling of the tablet layer.

14. A method according to any one of claims 1 to 13 further including the step of heating the tablet after applying the gel material-, wherein a portion of the gel material melts and then resets to form a smoother finish for the tablet. A cleansing tablet produced according to the method of any one of claims 1 to 14. PZ Cussons (International) Ltd 25 October 2004 arsm M0111598591v1 305412057