[0001] This invention relates to an agglomerated composition of improved colour and in particular
to white agglomerates of clay fabric softener for addition to white or differently
coloured detergent base powders.
[0002] Detergent powders without added colour are generally white or near-white in colour,
but some ingredients especially certain classes of fabric softening clay, enzyme granules
or bleach precursors may be brown, yellow or grey. The incidence of such discoloured
particles in a finished detergent powder can give the whole product an off-white unattractive
appearance.
[0003] GB 2 199 338 (Unilever Plc) proposes the use of large vividly coloured particles
("speckles") in detergent powder to render the presence of slightly discoloured particles
unnoticeable.
[0004] GB 2 121 843 (Colgate-Palmolive Co) proposes incorporating dyes or pigments in a
liquid agglomerating spray used in the manufacture of bentonite clay agglomerates
to form clay speckles.
[0005] In some powders however the use of speckles may not be desirable or may be ineffective
in camouflaging the discoloured particles.
[0006] We have surprisingly found that agglomerates coated or granulated with a whitening
particulate material of a certain average particle size, bulk density and reflectance
value (measured as R infinity at 460 nm which represents the reflectance value of
a layer so thick that a further increase in thickness of the layer fails to change
the reflectance) are often especially white, bright and unnoticeable when added to
a detergent base washing powder.
[0007] A first aspect of the present invention accordingly provides agglomerates comprising
whitening particulate material of average particle size less than 20 microns, a bulk
density of less than 400 grams per litre and a reflectance value (R infinity 460)
of greater than 85.
[0008] A second aspect of the invention provides a fabric softener comprising clay agglomerates,
said agglomerates comprising whitening particulate material of average particle size
less than 20 microns, a bulk density of less than 400 grams per litre and a reflectance
value (R infinity 460) of greater than 85.
[0009] A third aspect of the invention provides agglomerates comprising sufficient whitening
particulate material to give the agglomerate an R infinity 460 value greater than
75.
[0010] The agglomerates of improved colour can be formed either as a cogranulate with the
whitening particulate material or as agglomerates coated with the whitening particulate
material.
[0011] The cogranulated agglomerates preferably comprise from 30% to 60% by weight of the
particulate material, more preferably from 40% to 50% by weight.
[0012] The average particle size of the particulate material is preferably less than 15
microns, more preferably less than 10 microns.
[0013] The bulk density of the particulate material is preferably less than 250 grams per
litre.
[0014] The reflectance value measured as R infinity 460 is preferably greater than 95.
[0015] When the particulate material is present as a coating on the agglomerates it preferably
comprises from 10 to 40% by weight of the total agglomerate composition. More preferably
the particulate material comprises from 15 to 25% by weight of the total agglomerate
composition.
[0016] The particulate material is preferably a precipitated calcium carbonate or a silica.
The precipitated calcium carbonate employed can be in the form of particles of average
particle size of the order of 4 microns, built up from trigonal or aragonite crystals.
[0017] The silica employed is in the form of a precipitated amorphous powder of particle
size of the order of 10 microns.
[0018] A type of precipitated calcium carbonate which is most useful in whitening the agglomerates
is that which is known as SOCAL U3 (ex Solvay). A type of silica which is most useful
in whitening the agglomerates is that which is known as Microsil (ex Crosfields).
[0019] Clay softeners are well-known in the detergent patent literature. Included among
such clay softeners are various heat-treated kaolins and various multi-layer smectites.
GB 1 400 898 (Procter and Gamble) suggests the use of smectite clays having a relatively
high exchange capacity. There is a desire to boost the performance of fabric softening
clays in the wash and according to our copending patent application EP 287 344 it
has been found that if certain nonionic surfactant materials are carried on the clay,
at a specified level relative thereto, and the moisture content of the composition
is controlled, the fabric softening performance is enhanced. The examples of the invention
included herein are directed towards clay carrying a nonionic surfactant but it should
be understood that the invention is not limited to clays.
[0020] It has been found that the moisture content of clay agglomerates must be between
7.5% and 12% by weight, preferably from 8% to 10%. The term "moisture" in this context
is not necessarily the total water content, but rather it is the water which is lost
from the composition by drying in a static environment at 135°C to a constant weight.
Usually, when freshly prepared, the clay/nonionic agglomerates will have a higher
moisture content, such as, for example from 10% to 16% moisture, and will therefore
be too sticky for use, so that some post drying is necessary. When post-drying high
moisture content clay/nonionic agglomerates, a drying air temperature of 85-90°C has
been found to be suitable. Where the agglomerates are to be coated with precipitated
calcium carbonate it may be desirable to "over-dry" the agglomerates so that moisture
accommodated by the agglomerates as a result of the coating process leaves the agglomerates
with a final moisture content in the desired range.
[0021] The nonionic surfactant system exists as a cloudy phase in the temperature range
of 0°C to 80°C, preferably 0°C to 15°C in distilled water at 1% concentration. In
practise this means that the system has a cloud point of not more than 80°C, preferably
not more than 15°C. The cloud point correlates approximately to the hydrophilic-lipophilic
balance (HLB) of the surfactant system and it is therefore preferred that the HLB
should be less than 13.5, such as not more than 12.0, ideally less than 9.5. The HLB
should be above 6.0, preferably above 8.0 to provide sufficient detergency.
[0022] Specific nonionic surfactants are alkyl (C₆-C₂₂) phenols-ethylene oxide condensates,
the condensation products of aliphatic (C₈-C₁₈) primary or secondary linear or branched
alcohols with ethylene oxides, and products made by condensation of ethylene oxide
with the reaction products of propylene oxide and ethylenediamine.
[0023] The clay softener may be any such material capable of providing a softening benefit.
The effectiveness of a clay material as a fabric softener will depend on the level
of smectite clay. It is preferred that the ratio of the clay to the nonionic surfactant
in the agglomerate is from 3:1 to 20:1, most preferably 4:1 to 10:1.
[0024] Where the agglomerates are to be handled by conveyors, feeders, mixers, filling machinery
or are to be subjected to shipping shocks it may be necessary to employ a binder,
in addition to the nonionic if present, in the granulation process to improve the
structural stability of the agglomerate. Suitable binders include copolymers of polyacrylate
and maleic anhydride, polyacrylates, sugars, nonionic surfactants, polyethylene glycol,
polyoxyethylene alkyl ether, fatty acid monoethanolamide, carboxymethyl cellulose,
soap and latex.
[0025] The agglomerates can be made by known granulation processes typically by those described
in GB 2 121 843B. The cogranulated agglomerates can be made in any granulater where
the binding material can be contacted with materials to be agglomerated; preferably
a high shear, short residence time granulator, such as a Schugi Flexomix or a L ödige
Recycler, or a longer residence time, low shear granulater, such as a continuous drum
granulater, Eirich pan granulater or a drum or cement mixer. The coated agglomerates
can be made in any suitable device such as a rotary drum, pan or marumeriser mixer
using agglomerates made by a known granulation process.
[0026] Where the agglomerates are to be coated with the particulate material, it may be
desirable to include a binder in the coating solution (usually water) to aid adherence
of the particulate material to the agglomerate and to form durable bonds within the
coating layer.
[0027] A preferred process for forming coated agglomerates comprises granulating the agglomerates
with an excess of nonionic surfactant in a drum mixer to form "sticky" granules followed
by coating with the particulate material. The advantages of this process are that
an improved coating adherence and colour is obtained. The especially improved colour
is thought to be due to the fact that no binder is present at the light scattering
surface of the agglomerate.
[0028] A particularly preferred binder is Sokalan CP5 (ex BASF) a copolymer of maleic anhydride
and polyacrylate supplied as a 40% aqueous solution.
[0029] In addition to the binder it may be necessary to employ a plasticiser to improve
the friability resistance of the coating. For example the addition of 2% by weight
sorbitol or glycerol to the binder spray greatly decreases the friability of the agglomerate,
especially if the agglomerate is air dried.
[0030] When the agglomerates of the invention or the washing products containing them, contain
a detergent active material, this may be selected from nonionic detergent active materials,
anionic detergent active materials, zwitterionic or amphoteric detergent active materials
or mixtures thereof.
[0031] The anionic detergent active materials are usually water-soluble alkali metal salts
of organic sulphates and sulphonates having alkyl radicals containing from about 8
to about 22 carbon atoms, the term alkyl being used to include the alkyl portion of
higher acyl radicals. Examples of suitable synthetic anionic detergent compounds are
sodium and potassium alkyl sulphates, especially those obtained by sulphating higher
(C₈-C₁₈) alcohols produced for example from tallow or coconut oil, sodium and potassium
alkyl (C₉-C₂₀) benzene sulphonates, particularly sodium linear secondary alkyl (C₁₀-C₁₅)
benzene sulphonates; sodium alkyl glyceryl ether sulphates, especially those ethers
of the higher alcohols derived from tallow or coconut oil and synthetic alcohols derived
from petroleum; sodium coconut oil fatty monoglyceride sulphates and sulphonates;
sodium and potassium salts of sulphuric acid esters of higher (C₈-C₁₈) fatty alcohol-alkylene
oxide, particularly ethylene oxide, reaction products; the reaction products of fatty
acids such as coconut fatty acids esterified with isethionic acid and neutralised
with sodium hydroxide; sodium and potassium salts of fatty acid amides of methyl taurine;
alkane monosulphonates such as those derived by reacting alpha-olefins (C₈-C₂₀) with
sodium bisulphite and those derived from reacting paraffins with SO₂ and Cl₂ and then
hydrolysing with a base to produce a random sulphonate; and olefin sulphonates, which
term is used to describe the material made by reacting olefins, particularly C₁₀-C₂₀
alpha-olefins, with SO₃ and then neutralising and hydrolysing the reaction product.
The preferred anionic detergent compounds are sodium (C₁₁-C₁₅) alkyl benzene sulphonates
and sodium (C₁₆-C₁₈) alkyl sulphates.
[0032] When the fabric washing products contain a detergency builder material this may be
any material capable of reducing the level of free calcium ions in the wash liquor
and will preferably provide the composition with other beneficial properties such
as the generation of an alkaline pH, the suspension of soil removed from the fabric
and the dispersion of the fabric softening clay material.
[0033] Examples of phosphorus-containing inorganic detergency builders, when present, include
the water-soluble salts, especially alkaline metal pyrophosphate, orthophosphates,
polyphosphates and phosphonates. Specific examples of inorganic phosphate builders
include sodium and potassium tripolyphosphates, phosphates and hexametaphosphates.
[0034] Examples of non-phosphorus-containing inorganic detergency builders, when present,
include water-soluble alkali metal carbonates, bicarbonates, silicates and crystalline
and amorphous alumino silicates. Specific examples include sodium carbonate (with
or without calicte seeds), potassium carbonate, sodium and potassium bicarbonates
and silicates.
[0035] Examples of organic detergency builders, when present, include the alkaline metal,
ammonium and substituted ammonium polyacetates, carboxylates, polycarboxylates, polyacetyl
carboxylates and polyhydroxsulphonates. Specific examples include sodium, potassium
lithium, ammonium and substituted ammonium salts of ethylenediaminetetraacetic acid,
nitrilotriacetic acid, oxydisuccinic acid, melitic acid, benzene polycarboxylic acids
and citric acid.
[0036] Apart from the ingredients already mentioned, a number of optional ingredients may
also be present, either as part of the clay containing compositions or as part of
the overall fabric washing product.
[0037] Examples of other ingredients which may be present in the composition include the
lather boosters, lather depressants, oxygen-releasing bleaching agents such as sodium
perborate and sodium percarbonate, peracid bleach percursors, chlorine-releasing bleaching
agents such as tricloroisocyanuric acid, inorganic salts such as sodium sulphate,
and, usually present in very minor amounts, fluorescent agents, perfumes, enzymes
such as proteases, lipalases, cellulases and amylases, germicides and colourants.
[0038] When the agglomerates are included in a detergent base powder they are typically
present at a level from 5 to 20% by weight.
[0039] A typical formulation is as follows:
|
Parts by weight |
Lauryl alkyl sulphonate |
6 |
Nonionic detergent active |
3 |
Soap |
1.5 |
Zeolite |
22 |
Sokalan CP5 |
3 |
Alkaline silicate |
0.5 |
Perborate Monohydrate |
7.5 |
TAED |
1.8 |
Savinase |
0.35 |
Carbonate |
10.00 |
EDTA |
0.15 |
Sulphate |
24.39 |
SCMC |
0.50 |
Clay agglomerates |
10.00 |
Water, perfume, minors |
9.31 |
Examples
[0040] The invention will now be illustrated by the following non-limiting examples.
Example 1A
[0041] Clay/nonionic agglomerates were prepared by spraying 83 parts by weight of clay (KBU,
clay of cec <50 meq/100g ex Colin Stewart Minerals) with 17 parts of Synperonic A3
(a nonionic surfactant ex ICI which is a C₁₃-C₁₅ alcohol ethoxylated with approximately
3 moles of ethylene oxide per molecule and having a cloud point below 0°C) in a drum
mixer.
[0042] The agglomerates were tumbled in a drum coater with 20% by weight of Socal U3 (precipitated
calcium carbonate ex SOLVAY having a bulk density of 230 g/l a particle size of 4
microns, and an R infinity 460 of 96) and 20% by weight of a 25% solution of Sokalan
CP5. The moisture content of the agglomerates as made was 18%, these were dried to
a moisture content of 8%.
Example 1B
[0043] Example 1A was repeated excepting that the agglomerates were coated with 10% by weight
Microsil a silica (ex Crosfields) having a particle size of 10-15 microns, a bulk
density of 130 g/l and a reflectance value (R infinity 460) of 98.4.
Example 2
[0044] Example 1 was repeated excepting that the agglomerates were coated with 20% by weight
Durcal, a calcite (ex Omya) having a bulk density of 670 g/l a particle size of 4
microns and a reflectance value (R infinity 460) of 93.
Example 3
[0045] Example 1 was repeated excepting that the agglomerates were coated with 20% by weight
Speswhite, a kaolinite ex English China Clays Ltd (ECC).
[0046] Speswhite has a bulk density of 425 g/l, a particle size of 80% less than 2 microns
and a reflectance value R infinity 460 of 85.
Example 4
[0047] Clay/nonionic/precipitated calcium carbonate agglomerates were prepared by co-granulating
83 parts by weight of clay ('KBU) with 83 parts by weight Socal U3 using 24 parts
by weight of Synperonic A3 and 62 parts by weight of a 2% solution of Sokalan CP₅
as a granulating spray.
[0048] The agglomerates were then dried to a moisture content of approximately 8% on a fluidised
bed dryer using drying air having a temperature of 80°C.
Example 5
[0049] Example 4 was repeated excepting that the agglomerates were cogranulated with 83
parts by weight Speswhite a kaolin ex ECC in place of the Socal U3.
[0050] The reflectance of the agglomerates was then determined and is quoted in Table I
as an R460* (infinity) value which denotes, on a scale of 1 to 100 the amount of light
reflected back from a sample. The higher the reflectance value the whiter the sample.
R460* values presented here are an average of 5 with a least significant difference
of 0.5.
Table I
Example |
R460* |
1A |
80 |
1B |
80 |
2 |
58 |
3 |
66 |
4 |
80 |
5 |
62 |
1. An agglomerate comprising whitening particulate material of average particle size
less than 20 microns, a bulk density less than 400 grams per litre and a reflectance
value (R infinity 460) of greater than 85.
2. An agglomerate comprising sufficient whitening particulate material to give the
agglomerate an R infinity 460 value greater than 75.
3. An agglomerate as claimed in claim 1 or claim 2, wherein the whitening particulate
material is present as a coating on the agglomerate.
4. An agglomerate as claimed in claim 1 or claim 2 wherein the whitening particulate
material is present throughout the agglomerate as a cogranulate.
5. An agglomerate as claimed in any preceding claim wherein the bulk density of the
whitening particulate material is less than 250 grams per litre.
6. An agglomerate as claimed in any preceding claims wherein the average particle
size of the particulate material is less than 15 microns.
7. An agglomerate as claimed in any preceding claim wherein the average particle size
of the particulate material is less than 10 microns.
8. An agglomerate as claimed in claim 3 wherein the particulate material comprises
from 10 to 40% by weight of the total agglomerate composition.
9. A fabric softener comprising clay agglomerates, said agglomerates comprising whitening
particulate material of average particle size less than 20 microns, a bulk density
of less than 400 grams per litre and a reflectance value (R infinity 460) of greater
than 85.
10. A detergent composition comprising from 5% to 20% by weight of agglomerates as
claimed in claim 1.