WO2003044152A1

WO2003044152A1 - Detergent sachets

Info

Publication number: WO2003044152A1
Application number: PCT/EP2002/011603
Authority: WO
Inventors: Rudolfus J. H. Hafkamp
Original assignee: Unilever N.V.; Unilever Plc; Hindustan Lever Limited
Priority date: 2001-11-19
Filing date: 2002-10-16
Publication date: 2003-05-30
Also published as: AU2002350554A1

Abstract

The invention provides a water soluble sachet containing a particulate detergent composition wherein the particulate detergent composition comprises 25% by weight or less of the composition of particles having a particle size of 180 um or less. By controlling the particle size of the particles good dissolution of the particulate detergent composition is obtained. Furthermore, coherent sachets seals can be formed more readily.

Description

Detergent sachets

This invention relates to water soluble detergent sachets comprising a particulate detergent composition, in particular a laundry detergent or machine dishwashing composition.

For many years detergent compositions, especially laundry detergent compositions, have been provided commercially in forms such as free-flowing powders and liquids. For these products the consumer is required to determine and provide the correct dosage of the product at the point of use. This may lead to over dosing of the product and/or to *an increased risk of spillage or wastage.

More recently, detergent products have been commercially available in a form which provide a single dose of the detergent product for the consumer to add directly to the cleaning operation. Two examples of these single-dose products are laundry detergent tablets of compressed powder and water- soluble sachets of detergent composition which may contain the detergent product in liquid, paste or particulate form.

These single-dosage products are advantageous in that they obviate the need for the consumer to determine and measure the correct dosage and allow for more accurate dosing of the detergent product. They are also easier to handle and dispense, for example into the wash load, so reducing the risk of spillage and/or wastage.

Water-soluble sachets generally comprise a detergent composition encapsulated with water-soluble film, such as polyvinyl alcohol . Encapsulation allows for handling of the product without direct contact with the detergent composition. This is especially advantageous when the detergent composition comprises aggressive cleaning components which could irritate the skin on direct contact .

EP-A-479 404 (Unilever) describes a sachet or bag containing a cleaning composition wherein the sachet or bag is made of a continuous base film soluble in water with a second plastics material present as a discontinuous layer and which is less soluble than the base film material.

EP-A-253 566 (Procter & Gamble) describes a laundry product which comprises a particulate laundry composition releasably contained within a sachet formed of a film of water-soluble material, said film having an outer covering of a flexible, apertured, water-insoluble but water permeable non-woven, textile or paper sheet material.

WO 00/04125 (Henkel Kommanditgesellschaft auf Aktienname) describes a detergent composition in a bag made from a water- soluble film where at least 70% by weight of the detergent composition particles have a particle size of greater than 800 um.

US 4 410 441 (Lever Brothers) discloses detergent sachets of particulate material where the sachets have pores and the particle size of the particulate material is chosen so that the amount of material which can escape through the pores is minimised.

EP-A-0-163 417 (Unilever) discloses sachets of a bleaching composition wherein the bleach composition has a mean particle size in the range of at least 30 um, preferably in the range of from 100 to 900 um.

However, a problem encountered with water soluble sachets containing a particulate detergent composition is that the dissolution properties of the particulate composition are somewhat hindered, especially the speed of dissolution, compared to the same detergent composition used without the sachet. Without wishing to be bound by theory, it is believed that this may be at least in part caused by the tendency of the sachet to become trapped in an area with restricted water flow during the cleaning operation. For example, the sachet may become lodged between layers of laundry in a washing machine. This reduces the water flow around the sachet and hinders the dissolution of the particulate detergent composition inside.

This effect of reduced dissolution has been found to be less apparent in conventional methods of introducing a particulate detergent composition into a cleaning operation. For example, particulate detergent compositions used with a conventional dispensing device, such as a detergent ball or net, allow a good flow of water to pass through the dispensing device directly to the particulate detergent composition. Therefore, even if they become lodged in an area with reduced water flow, there should still be some water contacting with the particulate detergent composition to begin the dissolution process.

One way of reducing the dissolution speed of the particulate detergent composition may be to provide it in another physical form, such as, a finely divided powder. However, this has several disadvantages. Firstly, such a finely divided composition does not have the appearance or flow-properties of a free-flowing particulate detergent composition which has been found to be important to the consumer. Secondly, such compositions are more difficult to handle during their preparation and/or during filling of the sachet. Thirdly, it can be difficult to obtain a good seal on a sachet comprising such fine particulate material and this can lead to a loss of integrity of the sachet seal during storage or transport.

Therefore, there is a need to provide a water soluble sachet containing a free-flowing particulate detergent composition which has good dissolution properties of the composition in use. There is also a need to provide such a sachet which does not present significant handling problems during manufacture. Furthermore, these sachets should exhibit good integrity of the seal up to the point of use.

It is an object of the present invention to provide a water- soluble sachet containing a particulate detergent composition which addresses one or more of the above problems .

Broadly the present invention addresses one or more of the above problems by controlling the particle size of the particulate detergent composition to within specified limits .

Thus the invention provides a water soluble sachet containing a particulate detergent composition wherein the detergent composition comprises 25% by weight or less of the composition of particles having a particle size of 180 um or less.

Preferably the detergent composition comprises 20% by weight or less of the composition of particles having a particle size of 180 um or less. Advantages of controlling the particle size according to the present invention include quicker dissolution of the detergent composition to form a wash liquor. Furthermore, good sachet seal integrity is provided and the compositions do not present any unacceptable problems during manufacture of the powder or production of the sachet .

When the concentration of very fine particles in the detergent composition is controlled there is a reduced tendency for an unacceptable amount of the composition to form clumps and/or to adhere to the sachet as the sachet dissolves. Both of these undesirable effects can increase the dissolution time of the detergent composition. Furthermore, the detergent composition has a free-flowing appearance in the sachet which consumers find desirable.

Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word about." All amounts are by weight, unless otherwise specified.

Particle size

The particulate detergent composition comprises 25% by weight or less of the composition of particles having a particle size of 180 um or less, preferably 20% by weight or less, more preferably 18% by weight or. less .

It is preferred that the particulate detergent composition comprises 10% by weight or less of the composition of particles having a particle size of 1400 um or greater, preferably 5% by weight or less, more preferably 3% by weight or less.

The detergent composition preferably has a mean particle size in the range of from 300 um to 750 um or 800 um, more preferably in the range of from 450 um to 650 um, especially 500 um to 600 um.

The mean particle size referred to herein is measured by sieving the granules and collecting the sievings . The weight of the sieved fractions is plotted against the particle size of the fractions and the weight average mean particle size is then calculated following the method defined in Rosin and Rammler, J. Inst. Fuel, 7, 29-36 (1933) to give the weight average particle size.

Particulate detergent product

The particulate detergent composition may be any type of detergent composition- for which it is desirable to provide a single dose thereof in a water soluble sachet.

For example, the detergent composition may be a laundry (fabric cleaning, softening and/or treatment) composition or a machine dishwashing detergent composition.

Thus the detergent sachets are suitable for use in (fabric) washing machines and in dishwashing machines amongst other applications . They can also be used in the manual laundry and dishwashing operations.

The particulate detergent composition may contain particles which have been prepared by spray-drying or granulation and which contain a mixture of ingredients . Such particles may contain organic detergent surfactant and some, or all, of any water-softening agent (detergency builder) present in the composition. Suitable granulation and spray drying methods are well known in the art. The spray dried or granulated particles may be optionally mixed with other materials to form the particulate detergent composition.

The particulate detergent composition may have a bulk density of at least 400 g/litre, preferably at least 500 g/litre, and most preferably at least 600 g/litre.

a) Surfactant Compounds

The particulate detergent compositions typically comprise one or more organic surfactants . Many suitable detergent-active compounds are available and are fully described in the literature, for example, in "Surface-Active Agents and

Detergents", Volumes I and II, by Schwartz, Perry and Berch.

The surfactant may be anionic (soap or non-soap) , cationic, zwitterionic, amphoteric, nonionic or a combination of these. The preferred detergent-active compounds that can be used are soaps and synthetic non-soap anionic and nonionic compounds .

Anionic surfactant may be present in an amount from 0.5 to 50% by weight, preferably from 2% or 4% up to 30% or 40% by weight of the composition. Suitable examples include alkyl benzene sulphonates, particularly sodium linear alkyl benzene sulphonates having an alkyl chain length of Cs-Cis; olefin sulphonates; alkane sulphonates; dialkyl sulphosuccinates; and fatty acid ester sulphonates .

Suitable nonionic surfactant compounds include in particular the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom, for example, aliphatic alcohols, acids, amides or alkyl phenols with alkylene oxides, especially ethylene oxide .

Specific nonionic surfactant compounds are alkyl (C₈-₂₂) phenol- ethylene oxide condensates, the condensation products of linear or branched aliphatic C₈-2o primary or secondary alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylene-diamine .

In a fabric washing composition, these organic surfactants preferably provide from 5 to 50% by weight of the overall composition. In a machine dishwashing composition, organic surfactant is likely to constitute from 0.5 to 8% by weight of the overall composition and is likely to consist of nonionic surfactant, either alone or in a mixture with anionic surfactant .

b) Water-softening agent The detergent compositions may contain a so-called water- softening agent, which serves to remove or sequester calcium and/or magnesium ions in the water. In the context of a detergent composition containing organic surfactant, a water- softening agent is more usually referred to as a detergency builder.

When a water-softening agent (detergency builder) is present, the amount of it is likely to lie in a broad range from 5%, preferably 15 wt% up to 98% by weight of the composition. The amount is likely to be from 15 to 80% by weight, more usually 15 to 60% of the composition. Water-softening agents may be provided wholly by water soluble materials, or may be provided in large part or even entirely by water-insoluble material with water-softening properties.

Alkali metal aluminosilicates are strongly favoured as environmentally acceptable detergency builders for fabric washing. Suitable crystalline sodium aluminosilicate ion- exchange materials are described, for example, in GB 1 429 143 (Procter & Gamble) . The preferred sodium aluminosilicates of this type are the well known commercially available zeolites A and X, the newer zeolite P described and claimed in EP 384 070 (Unilever) and mixtures thereof. This form of zeolite P is also referred to as "zeolite MAP" . One commercial form of it is denoted "zeolite A24" (ex Ineos Silicas, UK) .

The builder may also be a water-soluble phosphorus-containing inorganic softener for example alkali-metal orthophosphates, metaphosphates, pyrophosphates and polyphosphates . Specific examples of inorganic phosphate detergency builders include sodium and potassium tripolyphosphates, orthophosphates and hexametaphosphates .

Non-phosphorus water-soluble detergency builders may be organic or inorganic. Inorganics that may be present include alkali metal (generally sodium) carbonate; while organics include polycarboxylate polymers, such as polyacrylates, acrylic/maleic copolymers, and acrylic phosphonates, monomeric polycarboxylates such as citrates, gluconates, oxydisuccinates, glycerol mono- di- and trisuccinates, carboxymethyloxysuccinates, carboxymethyloxymalonates, dipicolinates and hydroxyethyliminodiacetates . c) Bleach System

The detergent compositions according to the invention may contain a bleach system. This preferably comprises one or more peroxy bleach compounds, for example, inorganic persalts or organic peroxyacids, which may be employed in conjunction with activators to improve bleaching action at low wash temperatures. If any peroxygen compound is present, the amount is likely to lie in a range from 10 to 85% by weight of the composition. If the composition contains surfactant and detergency builder, the amount of peroxygen compound bleach is unlikely to exceed 25%wt of the composition.

Preferred inorganic persalts are sodium perborate monohydrate and tetrahydrate, and sodium percarbonate, advantageously employed together with an activator. Bleach activators, also referred to as bleach precursors, have been widely disclosed in the art .

d) Further optional ingredients Detergency enzymes may be employed in the compositions and are commonly employed in the form of granules or marumes, optionally with a protective coating, in amount of from about 0.1% to about 3.0% by weight of the composition.

The compositions may also contain a fluorescer (optical brightener) , for example, Tinopal (Trade Mark) DMS or Tinopal CBS available from Ciba-Geigy AG, Basel, Switzerland. Tinopal DMS is disodium 4, 4'bis- (2-morpholino-4-anilino-s-triazin-6- ylamino) stilbene disulphonate; and Tinopal CBS is disodium 2,2'-bis-(phenyl-styryl) disulphonate. An antifoa material is advantageously included if organic surfactant is present; especially if the detergent composition is primarily intended for use in front-loading drum-type automatic washing machines.

It may also be desirable that the composition comprises an amount of an alkali metal silicate. A composition for machine dishwashing will frequently contain at least 20 wt% silicate.

Further ingredients which can optionally be employed in laundry detergent compositions of the invention include anti- redeposition agents such as sodium carboxymethylcellulose, straight-chain polyvinyl pyrrolidone and the cellulose ethers such as methyl cellulose and ethyl hydroxyethyl cellulose, fabric-softening agents; heavy metal sequestrants such as EDTA; perfumes; and colorants or coloured speckles.

Sachet material

The water soluble sachet may be produced from any suitable material. This may be a film material, which can be of substantially uniform material or of non-woven texture. Non- woven films are preferred for bleach containing tablets because of the evolution of oxygen gas on storage where the small holes in the film allow the oxygen gas to escape.

Preferably the sachets are made from film or non-woven material having less than 10% by area, more preferably less than 5%, better less than 2% of material through which water can pass before the sachet begins to dissolve in use. It is especially preferred that the sachets are produced from a film material having substantially no apertures through which water can pass, before the sachet is in use, to contact with the particulate detergent composition inside. Film materials have been found to be especially advantageous .

Water soluble materials which may be used to form the water soluble sachets are widely disclosed in the literature and include, for example, polyester amides, polyvinyl alcohol, co- polymers of vinyl alcohol and methacrylate, polyethylene oxide, alginates, cellulose ethers such as carboxymethyl cellulose and methylcellulose, starches and starch derivatives, gelatin and any combination of these.

The desired degree of solubilisation can be achieved by • matching the type of packaging material and its thickness such that the desired solubilisation time is achieved.

Substantially uniform PVA film can for example be purchased from Chris Craft, Chicago, U. S .A. , reference CC8534 , and thermally non woven PVA fabric from BFF Nonwovens , Bridgewater, U.K. , product name SOLUFAB HEN30.

The water soluble sachet is preferably mainly composed of poly vinyl alcohol (PVA) or of a co-polymer of poly vinyl alcohol and poly methyl acrylate (PVA-PMA) . The term poly vinyl alcohol as used herein also includes partially hydrolysed poly vinyl acetates. The water soluble film can also contain minor quantities of plasticizers, antifoams, anti-oxidants, surfactants, perfumes and the like.

The exterior surface of the film may be treated with BITREX™ or similar material to discourage ingestion of the package of the invention by children. Sachet construction and use

The water soluble sachet may be of any suitable shape and construction and is preferably a flexible sachet.

The most convenient shapes from the viewpoints of both manufacture and packing are square and rectangular, but any other desired shape is also within the scope of the invention.

One other suitable form of sachet is in the form of a polyhedron having four or more walls and wherein each wall is inclined at an angle relative to each other wall, such as a tetrahedron (four-walled polyhedron) . The tetrahedron may be regular or irregular i.e. the walls may take the shape of regular or irregular polygons .

In use the sachets according to the invention are preferably, and conveniently, placed directly into the liquid which will form the wash liquor or into the area where this liquid will be introduced. The sachet dissolves on contact with the liquid, thereby releasing the particulate detergent composition.

EXAMPLES

The invention will be further described by reference to the following example. Further examples within the scope of the invention will be apparent to the Skilled Person.

A particulate laundry detergent composition having the composition set out in the table below was made by granulating the first eight ingredients together under high shear followed by densification under reduced shear to produce a base powder. To 61.05 grams of this base powder the other ingredients were added to produce a particulate detergent composition having the overall composition given below.

*^x Zeolite A24 is maximum aluminium zeolite P ex Ineos Silicas,

UK. *² NDOM is non detergent organic matter *³ Gerol™ soil release polymer *⁴ coated percarbonate available from Interox

*⁵ Dequest 2047 is ethylene diamine tetra methylene phosphonate available from Monsanto *⁶ Dequest 2016 is ethylene hydroxy diphosphonate available from Monsanto

The particulate composition had the following particle size distribution;

The mean particle size was 772 um +/- 34.5 um.

The particulate composition was encapsulated in a polyvinyl alcohol sachet and the sachet was sealed. The dissolution time of the detergent composition was monitored in washing tests and was found to have a faster dissolution time than an equivalent composition having more than 25% by weight of the composition of particles with a particle size of 180 um of less. Furthermore, the sachet seal was formed easily and was substantially free of particles of the detergent composition.

Claims

l.A water soluble sachet containing a particulate detergent composition wherein the particulate detergent composition comprises 25% by weight or less of the composition of particles having a particle size of 180 um or less.

2. A water soluble sachet according to claim 1 wherein the composition comprises 20% by weight or less of the composition of particles having a particle size of 180 um or less.

3. A water soluble sachet according to either claim 1 or claim 2 wherein the composition comprises 10% by weight or less of the composition of particles having a particle size of 1400 um or greater .

4. A water soluble sachet according to claim 3 wherein the composition comprises 5% by weight or less of the composition of particles having a particle size of 1400 um or greater.

5. A water soluble sachet according to any one of the preceding claims wherein the composition has a mean particle size in the range of from 300 um to 800 um.

6. A water soluble sachet according to any one of the preceding claims wherein the composition has a mean particle size in the range of from 450 um to 650 um.

7. A water soluble sachet according to any one of the preceding claims wherein the composition is a laundry detergent composition. A water soluble sachet according to any one of the preceding claims wherein the composition is a machine dishwash composition.