GB2283756A

GB2283756A - Particulate detergent composition

Info

Publication number: GB2283756A
Application number: GB9422554A
Authority: GB
Inventors: Jelles Vincent Boskamp
Original assignee: Unilever PLC
Current assignee: Unilever PLC
Priority date: 1993-11-11
Filing date: 1994-11-09
Publication date: 1995-05-17
Anticipated expiration: 2014-11-09
Also published as: DE4439418A1; GB9323300D0; SE9403856L; BR9404417A; ITTO940887A1; NL9401844A; ES2097700B1; FR2712298A1; FR2712298B1; ZA948558B; GB9422554D0; CH686960A5; GB2283756B; ES2097700A1; DE4439418B4; ITTO940887A0; SE9403856D0; IT1267492B1; BE1009038A5

Description

2283756 DETERGENT COMPOSITION This invention rialates to a detergent

composition and in particular to a particulate detergent composition having a low level of fine particles.

The use of detergent compositions for washing fabrics in a washing machine generally requires the detergent composition to be introduced to the wash by means of a dispensing device. Typically, washing machines have an integral dispensing drawer into which the detergent may be dosed and subsequently washed from the drawer into the wash compartment. Dispensing devices which are placed into wash compartment of the washing machine from which the detergent composition is dispensed are also known.

It is desirable that the detergent composition is dispensed into the wash without significant deposits being left in the dispensing device. Poor dispensing is undesirable as this causes a wastage of powder, the dosage of powder which reaches the wash is inaccurate thus leading to an inefficient wash cycle, the residue is unsightly in the dispensing device and the device must be cleaned between washes. Generally, a residue of more than about 10% of the powder dosed is considered as unacceptable and a residue of less than about 5% is preferable.

Dispensing problems have been encountered especially in the use of high bulk density detergent powders. It is believed that the low particle porosity of these powders may exacerbate dispensing problems. Furthermore, the temperature of the wash water may influence the dispensing properties of the powder, in particular greater residues may be left at lower wash water temperatures. Wash water temperatures below 20'C and in some cases below 1O'C are used and it is desirable that the powder dispenses satisfactorily at such temperatures and also at low water pressure.

C3567 2 Detergent powders may be produced by a spray-drying process but the high bulk density powders are generally produced by a process which involves mechanical mixing, for example, as disclosed in EP367339 (Unilever). The product of such a mixing process is herein referred to as a base powder. Further components may then be mixed with the base powder to provide a fully formulated detergent product.

We have found that high bulk density powders having excellent dispensing properties may be secured by controlling the particle size distribution of the base powder such that the level of fine particles does not exceed a specified level.

Accordingly the invention provides in a first aspect a particulate detergent composition having a high bulk density comprising a surfactant and a builder and having a particle porosity not in excess of 10% void volume wherein the particle size distribution of the particles is such that not more than 10% of the particles have a particle size not in excess of 180 microns.

Preferably the detergent composition is mixed with a further component to provide a formulated fully detergent product.

Suitably the detergent composition has a bulk density of at least 750g/1 and preferably at least 8OOg/l. Preferably the particles have a porosity not in excess of 8% void volume. The porosity is optimally between 3 and 8% void volume to provide a desirable combination of dispensing and dissolution properties.

Particle porosity is suitably determined using mercury porosimetry.

Preferably, the particle size distribution of the powder is such that no more than 5% of the particles have a particle size not in excess of 180 microns. It is further preferred that the composition does not comprise a significant proportion of large particles which may be referred to as C3567 is 3 - "oversize" particles. Preferably the particle size distribution of the powder is such that no more than 10% and more preferably no more than 5% of the particles have a particle size in excess of 1400 microns and desirably not in excess of 1000 microns.

Suitably the detergent composition has an average particle size of 200 to 1300 microns, preferably 400 to 1000 microns and more preferably 500 to 750 microns. The composition may be in powder form or in granular form as desired.

Suitably the dispensing characteristics of a cbmposition according to the invention provide a residue of less than 10% and preferably less than 5% of the powder dosed into a PHILIPS AWB 126/127 dispenser at a water temperature of 200C, preferably 1CC and a water flow rate of 5 litres per minute for 1 minute.

Powders according to the present invention are advantageous in that excellent dispensing is obtained thus permitting appropriate dosage of the powder in the wash, avoiding significant waste and reducing the need to clean the dispensing device.

A second aspect of the invention provides a process for the production of a detergent composition having a bulk density in excess of 750g/1 which comprises mixing the components of the composition to form particles and densifying the particles such that the particles have a porosity not in excess of 10% void volume and classifying the particles such that no more than 10% of the particles have a particle size not in excess of 180 microns.

The components of the composition may be mixed and densified in the same apparatus or in separate apparatus. The process may be continuous or batch as desired.

Preferably the components of the composition are mixed in a high shear step, for example in a LODIGE CB30 Recycler mixer for a period of 5 to 30 seconds, and the rate of mixing C3567 is in the apparatus is suitably 100 to 2500 rpm depending on the degree of densification and the particle size required. A granulation step may be employed if desired and may be carried out using a low speed mixer in a moderate shear step, for example a LODIGE KM300 Ploughshare mixer for a period of 1 to 10 minutes and a rate of mixing of 40 to 160 rpm in the apparatus. Batch processing in, for example, a FUKAE mixer may be employed if desired.

other mixing devices including those produced by Drais Schrugi may be employed as desired.

The components of the composition may compriseindividual components, particles which comprise a plurality of components, herein referred to as adjuncts and/or particles of a spray-dried powder. The process may therefore be a non-tower process wherein no spray drying step is employed or alternatively a post-tower process wherein the components of the composition which are mixed and densified comprise the product of a spraydrying process.

The particles may be classified by any suitable means, for example sieving. It is further preferred that following mixing and densification, the particles are dried and/or cooled, preferably in a fluid bed. Suitably the fluid bed is employed to remove excess levels of fine particles in the powder. In particular, where a drying or cooling step is employed elutriation of fine particles may be secured as the lower powder temperature and/or humidity may increase the efficiency of fines removal.

If desired, fine particles which are removed from the composition to provide a fines level not in excess of 10% may be recycled to the mixing and/or densification step.

Additional components may be post-dosed to compositions according to the invention in order to provide a fully formulated product as desired which should have a particle size distribution such that no more than 10% of the particles have a particle size not in excess of 180 microns.

C 11 C3567 Detergent compositions according to the present invention will generally contain a surfactant and builder and may also contain bleaching components and other active ingredients to enhance performance and properties. The surfactant may be selected from soap and non soap anionic, nonionic, amphoteric, cationic and/or zwitterionic. Anionic surfactants, for example linear alkyl benzene sulphonates, primary and secondary alkylsulphates, olefin sulphates, fatty acid ester sulphonates and alkyl ether sulphates, and nonionic surfactants, for example primary and secondary alcohol ethoxylates, alkylpolyglycosides and glycerol monoethers are preferred. Suitable examples are described in the literature, for example "Surface active agents and Detergent" Volumes I and II by Schwartz, Perry and Birch. The total amount of surfactant is suitably free from 5 to 40% by weight of the composition.

The builder may comprise inorganic and/or organic builders. Suitable builders include sodium carbonate, aluminosilicates preferably zeolites, for example ZEOLITE A24, phosphates and polymeric builders for example polycarboxylates and acrylic/maleic acid copolymers. The builder may comprise a silicate, preferably a crystalline layered silicate and optionally a zeolite and/or a salt, for example citrate. The builder is suitably present in an amount of from 10 to 80% and preferably from 15 to 60% by weight of the composition.

The composition may comprise a bleach system which may be oxygen or chlorine based. Peroxy bleach compounds for example inorganic persalts and organic peroxy acids, are preferred. Percarbonate is especially preferred. The bleach is suitably present in an amount of 5 to 35% by weight and preferably 10 to 25%.

A bleach activator may also be present, for example tetraacetyl ethylene diamine (TAED), suitably in an amount of from 1 to 8% by weight of the composition.

C3567 6 Other conventional components may be present in the composition including, silicate, fluorescer, carbonate, sulphate, powder structurant enzyme, perfume, dyes as desired. This list is not intended to be exhaustive.

The invention is illustrated by the following nonlimiting Examples.

Examole 1 A composition according to the present invention having the components as listed below was produced by mixing the components in a Lodige CB30 Recycler mixer to produce composition particles and subsequently densifying and agglomerating the particles to produce a powder having an average particle size in the range 550 to 700 microns, a particle porosity of less than 10% and a bulk density in excess of 750g11. Several components including perearbonate bleach, bleach activator, sodium silicate. sodium carbonate, enzyme fluorescer and perfume were post-dosed to the powder to produce a fully formulated powder comprising about 60% of the densified powder and about 40% post-dosed materials.

The densified powder comprised the following materials: Parts bv weiaht Anionic surfactant (Na-PAS) Nonionic surfactant Soap Zeolite A24 Sodium carbonate 22 3 55 2 The densified powder was sieved and the level of particles having a particle size of less than 180 microns was below 5%.

Comnarative Examnles Comparative compositions were produced having the same composition as described in Example 1 but with the level of particles of the densified powder having a particle size of less than 180 microns being in excess of 10%, specifically 20%, 30% and 40%.

i C3567 7 ExamDle 2 The dispensing properties of the compositions produced in Example 1 and the Comparative Example were tested by placing 100g of the composition into PHILIPS AWB 126/127 dispenser and passing water through the dispenser at a flow rate of 51/minute for 1 minute at 0.5 atmospheres pressure and measuring the amount of residue remaining in the dispenser as a percentage of the total composition. The experiments were conducted with water at a temperature of 100C and at 200C.

The results are shown in graph form in the attached Figure 1 which shows that compositions having a low level of fine materials provide excellent dispensing properties and in particular that compositions having a fine level not in excess of 5% provide no significant difference in dispensing properties at 100C and 200C.

C3567

Claims

Claims 1. A particulate detergent composition comprising a surfactant and

a builder and having a particle porosity not in excess of 10% void volume wherein the particle size distribution of the particles is such that no more than 10% of the particles have a particle size not in excess of 180 microns.
2. A composition according to Claim 1 in which no more than 5% of the particles have a particle size not in excess of 180 microns.
3. A composition according to claim for 2 having a particle porosity of 3 to 8% void volume.
4. A composition according to any preceding claim in which no more than 10% of the particles have a particle size in excess of 1400 microns.
5. A composition according to any preceding claims which provide a residue of less than 10% of the composition when dispensed from a dispenser of a PHILIPS AWB 126/127 at a water temperature of 200C and a water f low rate of 5 litres per minute for I minute.
6. A composition according to any preceding claim which comprises an anionic surfactant, a nonionic surfactant, and a builder which preferably comprises a silicate and a zeolite.
7. A detergent product comprising a detergent composition as defined in any preceding claim and a further component, preferably a precarbonate bleach, admixed therewith.
8. A process for the production of a detergent composition having a bulk density in excess of 750g/1 which comprises mixing the components of the composition to form particles and densifying the particles such that the particles have a porosity not in excess of 10% void volume and classifying the particles such that no more than 10% of the particles have a particle size not in excess of 180 microns.

C3567
9. A process according to claim 8 in which some of the components of the composition are mixed in a high shear step at a mixing speed of 100 to 2500 rpm and subsequently cooled and/or dried.
10. A process according to claim 9 in which the components of the compositions are mixed in a moderate shear step at a mixing speed of 40 to 160 rpm prior to or immediately after the high shear step.