Sachet product

Abstract: A sachet of flexible sheet material containing a composition, for example, for treating fabrics in a washing machine, so shaped and dimensioned that when immersed in water in the absence of the treatment composition its thickness at at least one point is at least 1 cm . The thickness of the sachet thus remains at least 1 cm after delivery of its contents, so that passage of the sachet between the inner and outer drums of an automatic washing machine is prevented or substantially reduced.

Description: TECHNICAL FIELD OF INVENTION This invention relates to sachets containing materials for treating fabrics in a washing machine. BACKGROUND AND PRIOR ART Sachets containing detergents and other treatment materials are well known in the washing art, for example, from EP 11 5008 and EP 163 417A (Unilever). These sachets of flexible sheet material may be water-permeable and deliver their contents by leaching out, or they may be designed so as to open during the wash cycle. US-A-4259373 discloses a pouch for a fabric softener composition, which pouch is made from four layers of nonwoven material having a total thickness of 1.66 cm. EP-A-99197 discloses laundry additive products in which a composition is combined with a water-insoluble carrier which may take the form of a sheet or a pouch. It is stated that a sheet should not be so small in area as to become trapped in crevices of the washing machine or clothes being washed nor so large as to be awkward to package and dispense. It has been found that both opening and non-opening sachets used in drum-type washing machines can undergo 'posting', that is to say, the sachet passes between the inner, rotating drum and the outer, stationary drum of the machine. The 'posted' sachet can then disrupt the normal functioning of the machine by, for example, blocking the pump inlet. Furthermore, full delivery of the sachet contents will not take place if 'posting' occurs early in the wash cycle. It is an object of the invention to provide a sachet having a substantially reduced inddence of 'posting'. A study of the use of simple non-opening sacnets in washing machines revealed that only 1-2% of such sachets underwent 'posting'. Further study showed, however, that not all machines were equally liable to 'post' sachets. 'Posting' was not found in some makes of machine whereas in others 'posting' occurred in 50% of trials. Other small objects, such as socks, are rarely found to undergo 'posting', perhaps because of their flexibility. A study of the motion of a sachet in a front-loading automatic washing machine revealed that'posting' tends to occur when the sachet has moved to the front of the machine, comes into contact with the door-window, and slides down into the gap between the drums. 'Posting' is more frequent towards the end of the wash cycle than at the start because the sachet contents have been exhausted and the empty sachet tends to be very thin, but can also occur much earlier. It has now been found that posting can be eiiminated or at least substantially reduced by making sure that, throughout the entire wash cycle, at least part of the sachet is sufficiently large that it cannot pass through the gap between the drums. SUMMARY OF INVENTION In a first embodiment, the present invention provides a sachet of flexible sheet material for a treatment composition, which sachet is a non-opening sachet consisting at least partially of water-permeable material characterised in that the sachet contains a water-insoluble ball so dimensioned that when the sachet is immersed in water in the absence of the treatment composition, the sachet has a thickness at at least one point which is at least 1 cm, whereby passage of the sachet between inner and outer drums of a drum-type automatic washing machine is prevented, or substantially reduced. In a second embodiment, the present invention provides a sachet of flexible sheet material for a treatment composition, which sachet is a non-opening sachet which in the dry state has a thickness smaller than 1 cm, consisting at least partially of water-permeable material characterised in that the sachet contains water-insoluble, water-swellable material which on immersion in water increases in bulk whereby the sachet then is so shaped and dimensioned that when immersed in water in the absence of the treatment composition the thickness of the sachet at at least one point is at least 1 cm, whereby passage of the sachet between inner and outer drums of a drum-type automatic washing machine is prevented, or substantially reduced. DETAILED DESCRIPTION OF THE INVENTION Sachets of the present invention fall into two classes: sachets which in the dry state and in the absence of the treatment composition have a thickness at at least one point of at least 1 cm (the first embodiment) and those which are thinner than 1 cm in the dry state in the absence of the treatment composition but acquire such a minimum dimension on immersion in water (the second embodiment). Sachets according to both embodiments are of the non-opening type, which deliver their contents by leaching out through a water-permeable wall. In the first embodiment of the invention the insoluble ball prevents the sachet from being 'posted' by increasing its thickness. Sachets of the first embodiment, although very satisfactory as non-posting sachets, do suffer from the minor disadvantage that they are somewhat more bulky than other sachets, leading to increased storage space requirements and packaging costs. This problem is avoided with the second embodiment of the invention according to which the sachet in the dry state has, in the absence of the treatment material, a thickness smaller than 1 cm but on immersion in water increases in bulk whereby the thickness of the wet sachet at at least one point is at least 1 cm. This is conveniently achieved by including in the sachet a water swellable material which increases in bulk whereby the sachet then has a thickness at at least one point of at least 1 cm after immersion in water. This material is conveniently in the form of a small object or "insert". In a non-opening sachet the insert may simply be loose, while if the sachet is of the opening variety it will, of course, be necessary to secure the insert and the sachet together, for example, by glueing. If secured, the insert could if desired be on the outside of the sachet. A preferred insert is a small piece of the compressed sponge material sold under the Trade Mark 'Spontex'. This material is especially useful in that it can be compressed to a state in which, on wetting, it expands rapidly in one dimension to at least five times the compressed size while remaining substantially unchanged in the other two dimensions. Thus a 2 cm square of this material having a thickness of 0.2 cm will expand rapidly on wetting to a thickness of 1.5-2 cm to give a cuboid of approximate dimensions 2 × 2 × (1.5-2) cm, i.e. the thickness increases dramatically while the other dimensions are unchanged. Such an insert can be packed flat in a sachet which is thus conveniently thin in the dry state, but will swell up quickly when the sachet encounters the water of the washing machine. The insert can be of any shape: square, rectangular, or especially triangular inserts are preferred as they may be cut from the bulk material with minimal wastage. Other materials may, of course, also be used to impart water-swellability to the sachet. In a closed sachet the material need not be a discrete insert but may take the form of balls, beads, granules or powder. Certain water-swellable polymers, for example, the starch and cellulose derivatives used as "superabsorbents", may be suitable provided that the swelling is not too sensitive to temperature. It is preferred that the water-swellable material should swell before all the sachet contents have been delivered: in practice most sponge materials will swell almost instantarieously. NATURE OF THE SACHET WALLS Preferably the sachet walls, which are of flexible sheet material, comprise paper, woven fabric, non-woven fabric, or plastics film, or laminates of these materials. The sachet walls must of course be compatible with the treatment composition to be contained in the sachet. The seams or seals of the sachet may be formed by any method, heat-sealing or glueing being preferred. NATURE OF TREATMENT COMPOSITION The sachet is intended to contain any treatment composition useful for treating fabrics in the washing machine. Examples of such compositions include fully formulated detergents, bleaches, bleach activators, fabric conditioners, and other detergent ingredients or combinations thereof. Alternatively the sachet may contain materials useful for treating the washing machine itself. An example of such a treatment would by the removal of a accumulated calcium- or phosphate-containing scale. If the machine treatment material is neutral or alkaline, for example, a salt of EDTA, then the treatment may be carried out at the same time as the fabric washing. If the machine treatment material is acidic, for example, citric acid or adipic acid, then it is preferred that the machine treatment be carried out as a separate operation. According to one especially preferred embodiment of the invention, the sachet is intended as a bleach adjunct for use in conjunction with a detergent powder, and contains sodium perborate and an activator therefor: a closed sachet of this type is described and claimed in EP 163 417A (Unilever). It is especially preferred that the sodium perborate be in monohydrate form and that the activator be tetraacetylethylenediamine (TAED). The sachet may also be employed in other aqueous environments, for example in swimming pools. The invention will be illustrated by reference to the following non-limiting Examples. EXAMPLE 1 Sachet products in accordance with the invention were prepared from a porous nonwoven fabric, of average pore size 70 µm, consisting of 40% polyester fibres and 60% viscose fibres, coated on one side (the inside of the sachet) with a polyamide heat-seal finish. Each sachet was square and had dimensions of 10 cm × 10 cm. Three sides of the each sachet were sealed together by heat-sealing, and it was filled with the following bleaching composition: Sodium perborate monohydrate (ex Degussa, particle size substantially 100-700 µm) 9.7 g TAED granules (300-200 µm) (65.3% TAED, 32% phosphates, 2.7% water) 13.9 g Perfume 0.3 g Fluorescer (CBSX ex CIBA-Geigy) 0.12 g A small square of compressed 'Spontex' (ex Spontex, 24 Rue de Jeuneurs, 75002 Paris) sponge material having dimensions of 2 cm × 2 cm and a thickness of 0.2 cm was placed flat inside each sachet with the bleaching composition, and the fourth side of the sachet was dosed by heat-sealing. EXAMPLE 2 A sachet similar to that described in Example 1 was prepared by the same method. However, the sachet contained a piece of 'Spontex' 1.5 cm square which is capable of expanding to a height of 1.6 cm on wetting. EXAMPLE 3 As Example 2 but containing a 'Spontex' insert of 1 × 2 cm. EXAMPLE 4 As Example 2 but containing a 'Spontex' insert of 2 cm square, which was capable of expanding to a height of 2.1 cm on wetting. EXAMPLE 5 As Example 5 but containing a drcular 'Spontex' insert of 2 cm diameter. EXAMPLE 6 A similar sachet to that described in Example 1 was prepared by the same method. The sachet, however, contained a cube of uncompressed sponge material having a 1.5 cm side instead of 'Spontex'. EXAMPLE 7 A similar sachet to that described in Example 1 was prepared by the same method. The sachet contained a hollow polyethylene ball of 2 cm diameter instead of 'Spontex'. Comparative Example A A similar sachet to that described in Example 1 was prepared by the same method. The sachet did not contain an insert or an external protrusion. POSTING TESTS The sachets of Examples 1-7 and Comparative Example A were tested in a range of washing machines. A similar wash load and cycle were used for each test of a particular machine. The results are set out in the table. It is clear from the table that sachets of the invention did not undergo 'posting' whereas conventional sachets were prone to 'posting'; in one case in more the half the trials the conventional sachets tested underwent posting. Miele W753 Miele W753 Laden 585 Philips 921 Zanussi SL27T No. tested No. posted No. tested No. posted No. tested No. posted No. tested No. posted No. tested No. posted Example A (comparative) 30 4 - - - 200 104 Example 1 36 0 9 0 32 0 14 0 - - Example 2 20 0 - - - - Example 3 15 0 - - - - Example 4 36 0 9 0 32 0 14 0 - Example 5 36 0 9 0 32 0 14 0 Example 6 - - - - - 10 0 Example 7 - - - - 25 0 Gap between inner and outer drums: the difference in the gaps between the drums is due to manufacturing tolerances 5-13 mm 8-11 mm 5-10 mm 5-12 mm

Claims: A sachet of flexible sheet material for a treatment composition, which sachet is a non-opening sachet consisting at least partially of water-permeable material characterised in that the sachet contains a water-insoluble ball so dimensioned that when the sachet is immersed in water in the absence of the treatment composition, the sachet has a thickness at at least one point which is at least 1 cm, whereby passage of the sachet between inner and outer drums of a drum-type automatic washing machine is prevented, or substantially reduced. A sachet of flexible sheet material for a treatment composition, which sachet is a non-opening sachet which in the dry state has a thickness smaller than 1 cm, consisting at least partially of water-permeable material characterised in that the sachet contains water-insoluble, water-swellable material which on immersion in water increases in bulk whereby the sachet then is so shaped and dimensioned that when immersed in water in the absence of the treatment composition the thickness of the sachet at at least one point is at least 1 cm, whereby passage of the sachet between inner and outer drums of a drum-type automatic washing machine is prevented, or substantially reduced. A sachet as claimed in claim 2, wherein the water-swellable material is in the form of a piece of compressed sponge material.

Inventors: FORET ROGER, WALKER ADRIAN WILLIAM, WALLAERT RAYMOND JEAN, FORET, ROGER, WALKER, ADRIAN WILLIAM, WALLAERT, RAYMOND JEAN
Applicants: UNILEVER NV, UNILEVER PLC, UNILEVER N.V.
Application year: 1987
Main classification: D06F39
IPC codes: D06M23, D06F39, C11D17