Note: Descriptions are shown in the official language in which they were submitted.
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DETERGENT COMPOSITIONS
TECHNICAL FIELD
The present invention relates to detergent
compositions in the form of tablets of compacted
detergent powder containing sodium percarbonate.
BACKGROUND AND PRIOR ART
Detergent compositions in tablet form have been
known for many years although the form has never achieved
great popularity on the market. In principle, tablets
offer several advantages over powder products: they do
not require measuring and are thus easier to handle and
dispense into the the washload, and they are more
compact, hence facilitating more economical packaging and
storage.
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One difficulty that has been experienced in the
formulation of detergent tablets is the incorporation of
bleaching ingredients, especially when the presence of
bleach-sensitive ingredients such as enzymes is also
desired: in a compressed tablet, the ingredients are
much more intimately associated with one another than in
a powder, and any adverse interactions and instability
will be exacerbated.
GB 911 204 (Unilever) discloses layered detergent
tablets containing persalt bleach, for example, sodium
perborate, and certain bleach activators, for example,
sodium acetoxybenzene sulphonate and phthalic anhydride.
To avoid destabilisation, the bleach activator is
segregated from the remaining tablet ingredients,
including the persalt bleach, in a separate section or
layer.
In contrast, EP 395 333A (Unilever) discloses a
detergent tablet containing sodium perborate in
conjunction with one or more bleach-sensitive ingredients
- tetraacetylethylenediamine or similar bleach
activator, enzyme, fluorescer, or any combination of
these - as well as detergent-active compounds,
detergency builders and optionally other ingredients.
The persalt is not segregated from the bleach-sensitive
ingredients but, surprisingly, the tablet is stable with
no more loss of bleach, enzyme or fluorescer performance
on storage than in a powder of the same composition.
Sodium percarbonate, Na2CO3.1.5H202, is less stable
than sodium perborate in the presence of moisture:
unlike sodium perborate, which exists as a tetrahydrate
and a monohydrate, it is anhydrous, and when it absorbs
water hydrogen peroxide is liberated and this decomposes
readily. Stabilisation of sodium percarbonate in
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detergent powders has long been recognised as a
difficulty: its incorporation in tablets would therefore
be expected to be even more problematic.
The problem becomes especially acute if sodium
percarbonate is to be included in a detergent powder with
a high free moisture content, when it tends to become
deactivated on storage. This situation applies in
particular to powders containing crystalline alkali metal
aluminosilicates (zeolites), because those materials
contain a large amount (about 10-15 wt% in zeolite 4A,
for example) of relatively mobile water.
Detergent tablets containing sodium percarbonate are
disclosed in US 3 953 350 (Kao) but the detergency
builder is sodium tripolyphosphate. JP 60 015 500A
(Lion) discloses tablets containing anionic surfactant,
zeolite, sodium sulphate, and a sodium bisulphate/sodium
percarbonate bleach system.
GB 1 50S 274 (Colgate-Palmolive) discloses detergent
compositions in the form of a plurality of small dosage
units, for example sachets but preferably and
specifically tablets, containing different ingredients
that can be dosed individually by the consumer. A
three-tablet system is described (Example 6) consisting
of a detergent tablet (surfactant, builders, fluorescer,
colourant), a separate builder tablet (additional
builder), and a separate bleach tablet (sodium
percarbonate and nonionic surfactant).
The present invention now presents a solution to the
problem of how to prepare a storage-stable detergent
tablet containing both sodium percarbonate and
ingredients to which it is sensitive. Surprisingly, the
tablet of the invention also shows improved dissolution
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in the wash liquor.
D~lNl~llON OF THE lNv~NllON
The present invention provides a tablet of
compressed particulate detergent composition comprising a
detergent-active compound, a detergency builder, a bleach
system comprising sodium percarbonate, and optionally
other detergent ingredients, wherein the percarbonate is
separated from any ingredient of the composition
detrimental to its stability by segregation in a discrete
region of the tablet.
DETAILED DESCRIPTION OF THE INVENTION
Detergent tablets of the invention solve the problem
of percarbonate instability by segregating that material
and isolating it from other ingredients which may
interact adversely with it. Greatly improved storage
stability is observed even when the detergent base
composition contains zeolite, with its large amounts of
associated mobile water. Surprisingly, the segregated
tablets of the invention also dissolve more quickly in
the wash liquor than do similar tablets in which the
sodium percarbonate is simply mixed homogeneously with
other ingredients before tabletting.
Percarbonate segregation
In the tablet of the invention, at least one
discrete region comprising sodium percarbonate and
optionally other ingredients compatible with sodium
percarbonate is present. Other components such as
detergent-active compound, detergency builder and any
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other ingredients of doubtful compatibility with sodium
carbonate are excluded from the discrete region(s) in
which the sodium percarbonate is segregated.
Various means may be used to achieve the
segregation. The percarbonate may, for example, be
isolated in a layer, core or insert, while other
ingredients are present in other layers, or in the main
body or matrix of the tablet. More than one layer, core
or insert may be present. Another possibility is the
use of relatively large granules or noodles distributed
throughout the main body or matrix of the tablet, the
granules or noodles being protected by coating or
encapsulation. Suitable coating materials or
encapsulants will readily suggest themselves to the
skilled detergent formulator.
A preferred embodiment of the invention which is
simple in structure and simple to manufacture is a tablet
consisting of two layers: the first layer containing the
percarbonate, and the second layer containing other
ingredients. Each layer is preferably substantially
homogeneous, that is to say, is the compaction product of
a single particulate composition, although that
particulate composition may have been prepared by mixing
a number of components and all its particles will not
necessarily be identical.
The percarbonate may be segregated alone, or
together with one or more other ingredients that are
fully compatible with it. It is generally preferred that
a major proportion of the non-percarbonate ingredients
should be separated from the percarbonate.
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However, the stability of the percarbonate may
actually be increased by segregating it together with a
diluent in the form of a compatible inorganic salt. The
salt is preferably in a finely divided or highly porous
form having a preferred surface area, as measured by
nitrogen absorption of 5.15m2/g. It is believed that
the inorganic salt contributes to percarbonate stability
by acting as a moisture sink. One especially preferred
inorganic salt is sodium carbonate, which of course also
plays a useful role in the detergent composition as a
whole, as a detergency builder and provider of
alkalinity. It is believed that sodium carbonate may
also contribute to percarbonate stability by reabsorption
of any liberated hydrogen peroxide.
According to one especially preferred embodiment of
the invention, the diluent is in the form of a
spray-dried composition comprising the compatible
inorganic salt, more preferably sodium carbonate, and a
polymeric binder.
The binder must itself be stable to oxidation.
Preferred binders are acrylic and/or maleic polymers, for
example, the acrylic/maleic copolymer sold commercially
as Sokalan (Trade Mark) CP5 ex BASF. As well as their
binder function which improves tablet integrity and
allows tabletting without having to wet the percarbonate
to any significant degree, polycarboxylate polymers of
this type also have a useful detergency building and
antiredeposition action.
In this embodiment of the invention, the discrete
tablet region or layer is the compaction product of a
particulate composition prepared by mixing sodium
percarbonate with the spray-dried salt/polymeric binder
granules. This particulate starting composition
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suitably contains from 30 to 70 wt% of sodium
percarbonate, from 30 to 70 wt% of the inorganic salt
(preferably sodium carbonate), and from 0.5 to 5 wt% of
the polymeric binder.
The total amount of sodium percarbonate in the
tabletted composition as a whole is preferably within the
range of from 5 to 40 wt%, more preferably from 10 to
30 wt%.
Other ingredients
As well as sodium percarbonate, the detergent tablet
of the invention contains at least one detergent-active
compound, at least one detergency builder, and optionally
other ingredients. Preferred tablets of the invention
provide a fully formulated, high performance detergent
composition within a single tablet.
Detergent-active compounds
Detergent-active compounds are suitably present in
an amount of from 2 to 50 wt%, more preferably from 5 to
40 wt%. Detergent-active material present may be
anionic (soap or non-soap), cationic, zwitterionic,
amphoteric, nonionic, or any combination of these.
Anionic detergent-active compounds may be present in
an amount of from 2 to 40 wt%, preferably from 4 to
30 wt%.
Synthetic anionic surfactants are well known to
those skilled in the art. Examples include alkylbenzene
sulphonates, particularly sodium linear alkylbenzene
sulphonates having an alkyl chain length of C8-C15;
primary and secondary alkyl sulphates, particularly
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sodium C12-C15 primary alcohol sulphates; olefin
sulphonates; alkane sulphonates; dialkyl
sulphosuccinates; and fatty acid ester sulphonates.
It may also be desirable to include one or more
soaps of fatty acids. These are preferably sodium soaps
derived from naturally occurring fatty acids, for
example, the fatty acids from coconut oil, beef tallow,
sunflower or hardened rapeseed oil.
Anionic surfactants are preferably concentrated in
discrete domains as described and claimed in our
copending Canadian application 2,046,483 (Unilever PLC).
Suitable nonionic detergent compounds which may be
used 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 either alone or with propylene oxide.
Specific nonionic detergent compounds are alkyl
(C6 22) phenol-ethylene oxide condensates, the
condensation products of linear or branched aliphatic
C8 20 primary or secondary alcohols with ethylene oxide,
and products made by condensation of ethylene oxide with
the reaction products of propylene oxide and
ethylenediamine. Other so-called nonionic detergent
compounds include long-chain tertiary amine oxides,
tertiary phosphine oxides, and dialkyl sulphoxides.
Especially preferred are the primary and secondary
alcohol ethoxylates, especially the C12 15 primary and
secondary alcohols ethoxylated with an average of from 5
to 20 moles of ethylene oxide per mole of alcohol.
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The nonionic detergent-active compounds are
preferably concentrated in discrete domains. Since the
nonionic detergent compounds are generally liquids, these
domains are preferably formed from any of the well-known
carriers in the detergent business impregnated by
nonionic detergent-active compound. Preferred carriers
include zeolite; zeolite granulated with other materials,
for example, Wessalith CS (Trade Mark), Wessalith CD
(Trade Mark), Vegabond GB (Trade Mark), sodium perborate
monohydrate; Burkeite (spray-dried sodium carbonate and
sodium sulphate as disclosed in EP 221 776 (Unilever)).
Nonionic detergent-active compounds may optionally
be mixed with materials which make the granules slow
wetting and/or prevent the nonionic leaching out into the
main tablet matrix. Such materials may suitably be fatty
acids, especially lauric acid.
DeterqencY builders
The detergent tablets of the invention contain one
or more detergency builders, suitably in an amount of
from 5 to 80 wt%, preferably from 20 to 80 wt%.
The invention is of especial relevance to tablets
derived from detergent compositions containing alkali
metal aluminosilicates as builders, since these builders
have a particular tendency to destabilise sodium
percarbonate. In the tablet of the invention,
aluminosilicate builders must always be excluded from the
region containing the sodium percarbonate.
Alkali metal (preferably sodium) aluminosilicates
may suitably be incorporated in amounts of from 5 to 60%
by weight (anhydrous basis) of the composition, and may
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be either crystalline or amorphous or mixtures thereof,
having the general formula:
0.8-1.5 Na20. Al203Ø8-6 Si02
These materials contain some bound water and are
required to have a calcium ion exchange capacity of at
least 50 mg CaO/g. The preferred sodium aluminosilicates
contain 1.5-3.5 SiO2 units (in the formula above). Both
the amorphous and the crystalline materials can be
prepared readily by reaction between sodium silicate and
sodium aluminate, as amply described in the literature.
Suitable crystalline sodium aluminosilicate
ion-exchange detergency builders 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, and
mixtures thereof. Also of interest is the novel
zeolite P described and claimed in EP 384 070A.
Other builders may also be included in the detergent
tablet of the invention if necessary or desired: suitable
organic or inorganic water-soluble or water-insoluble
builders will readily suggest themselves to the skilled
detergent formulator. Inorganic builders that may be
present include alkali metal (generally sodium)
carbonate; while organic builders include polycarboxylate
polymers such as polyacrylates, acrylic/maleic
copolymers, and acrylic phosphinates; monomeric
polycarboxylates such as citrates, gluconates,
oxydisuccinates, glycerol mono-, di- and trisuccinates,
carboxymethyloxysuccinates, carboxymethyloxymalonates,
dipicolinates, hydroxyethyliminodiacetates; and
organic precipitant builders such as alkyl- and
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alkenylmalonates and succinates, and sulphonated fatty
acid salts.
Especially preferred supplementary builders are
polycarboxylate polymers, more especially polyacrylates
and acrylic/maleic copolymers, suitably used in amounts
of from 0.5 to 15 wt%, especially from 1 to 10 wt%; and
monomeric polycarboxylates, more especially citric acid
and its salts, suitably used in amounts of from 3 to 20
wt%, more preferably from 5 to 15 wt%. As previously
indicated, at least part of any polymer required in the
formulation may be incorporated, as binder, in the region
of the tablet in which the sodium percarbonate is
segregated.
Preferred tabletted compositions of the invention
preferably do not contain more than 5 wt% of inorganic
phosphate builders, and are desirably substantially free
of phosphate builders. However, phosphate-built
tabletted compositions are also within the scope of the
invention.
Bleach activators
To enhance the low-temperature performance of sodium
percarbonate, a bleach activator (bleach precursor) is
advantageously present. The bleach activator should be
excluded from the region in which the sodium percarbonate
is segregated.
Preferred bleach activators include peracetic acid
precursors, for example, tetraacetylethylenediamine
(TAED), and perbenzoic acid precursors. The novel
quaternary ammonium and phosphonium bleach activators
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disclosed in US 4 751 015 and US 4 818 426 (Lever
Brothers Company) and the monosaccharide esters as
disclosed in EP 0 380 437A (Procter & Gamble; Novo) are
also of great interest.
Bleach activators are suitably present in an amount
of from 1 to 10 wt%, more preferably from 2 to 5 wt%.
Detergent tablets containing persalts and bleach
activators are also described and claimed in our
copending British patent application of even date (Case
C3390).
Bleach stabilisers
The bleach system may also include a small amount of
a bleach stabiliser (heavy metal sequestrant) such as
ethylenediamine tetraacetate (EDTA), ethylenediamine
tetramethylene phosphonate (EDTMP) or diethylenetriamine
pentamethylene phosphonate (DTPMP).
Enzymes
The detergent tablets of the invention may also
contain one of the detergency enzymes well-known in the
art for their ability to degrade and aid in the removal
of various soils and stains. Most enzymes are
bleach-sensitive to some extent, and should also be
excluded from the region containing the sodium
percarbonate.
Suitable enzymes include the various proteases,
cellulases, lipases, amylases, and mixtures thereof,
which are designed to remove a variety of soils and
stains from fabrics. Examples of suitable proteases are
Maxatase (Trade Mark), as supplied by Gist-Brocades N.V.,
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Delft, Holland, and Alcalase (Trade Mark), Esperase
(Trade Mark) and Savinase (Trade-Mark), as supplied by
Novo Industri A/S, Copenhagen, Denmark. Detergency
enzymes are commonly employed in the form of granules or
marumes, optionally with a protective coating, in amounts
of from about 0.1% to about 3.0% by weight of the
composition; and these granules or marumes present no
problems with respect to compaction to form a tablet.
Minor ingredients
The detergent tablets of the invention 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 antifoam material is advantageously included in
the detergent tablet of the invention, especially if the
tablet is primarily intended for use in front-loading
drum-type automatic washing machines. Suitable antifoam
materials are usually in granular form, such as those
described in EP 266 863A (Unilever). Such antifoam
granules typically comprise a mixture of silicone oil,
petroleum jelly, hydrophobic silica and alkyl phosphate
as antifoam active material, sorbed onto a porous
absorbent water-soluble carbonate-based inorganic carrier
material. Antifoam granules may be present in any amount
up to 5% by weight of the composition.
It may also be desirable to include in the detergent
tablet of the invention an amount of an alkali metal
silicate, particularly sodium ortho-, meta- or preferably
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neutral or alkaline silicate. The presence of such
alkali metal silicates at levels, for example, of 0.1 to
10 wt%, may be advantageous in providing protection
against the corrosion of metal parts in washing machines,
besides providing some measure of building and giving
processing benefits.
Further ingredients which can optionally be employed
in the detergent tablet of the invention include
antiredeposition 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; pigments, colourants or coloured
speckles; and inorganic salts such as sodium and
magnesium sulphate. Sodium sulphate may if desired be
present as a filler material in amounts up to 40% by
weight of the composition; however as little as 10% or
less by weight of the composition of sodium sulphate, or
even none at all, may be present.
As well as the functional detergent ingredients
listed above, there may be present various ingredients
specifically to aid tabletting or to aid tablet
dispersion in the wash, for example, binders,
disintegrants, or lubricants. As already indicated,
some ingredients may give both functional wash benefits
and tabletting benefits.
Tabletting
As previously indicated, the tablets of the
invention are prepared by compaction of particulate
starting material. Any suitable compaction process may
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be used, for example, tabletting, briquetting or
extrusion, but tabletting is the preferred and most
suitable process.
For any given starting composition, the time taken
for the tablet to disintegrate in the wash liquor will
vary with the compaction pressure used to form the
tablet. If the compaction pressure is too low, the
tablet will tend to crumble and break up in the dry
state, on handling and packaging; an increase in
compaction pressure will improve tablet integrity, but
eventually at the expense of disintegration time in the
wash liquor.
Using an Instron (Trade Mark) Universal Testing
Machine at constant speed, or a Research and Industrial
screw hand press, to operate a steel punch and die, it
has been found that effective tablets may be produced
using compaction pressures ranging from 0.1 to 500 MPa
(0.01 to 50 kN/cm ), especially from 0.2 to 100 MPa (0.02
to 10 kN/cm ).
The optimum compaction pressure will depend to some
extent on the starting composition; for example, a
formulation containing a high proportion of organic
ingredients (for example, surfactants) and a low
proportion of inorganic salts may require a compaction
pressure lower than that required for a formulation
containing a lower proportion of organic ingredients and
a higher proportion of inorganic salts; and a dry-mixed
formulation will generally require a higher pressure than
will a spray-dried powder.
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Preferred tablet forms
Preferred tablets having improved disintegration and
dissolution properties are described and claimed in our
copending Canadian Patent Applications Nos. 2,046,453, 2,046,483 and
2,072,766 (Unilever PLC). These preferred tablet forms have particular
relevance for tablets of fully formulated delerg~nt compositions.
The tablet described and claimed in Application No.
90 15503.7 or a discrete region thereof, consists
essentially of a matrix of particles substantially all of
which have a particle size within a range having upper
and lower limits each lying within the range of from 200
to 2000 ~m and differing from each other by not more than
700 ~m.
According to Application No. 90 15504.5, a tablet of
compacted particulate detergent composition comprises a
minor proportion (2-40 wt%) of a first component (a)
which contains 20-100 wt% anionic surfactant, the rest of
the composition containing only 0-3 wt% anionic
surfactant.
The tablet described and claimed in our copending
British Application C3408, filed on 1 July 1991, or a
discrete region thereof, consists essentially of a matrix
of particles substantially all of which have a particle
size ~200~m, at least the particles of detergent-active
compound and detergent builder are coated with
binder/disintegrant before tablet compaction.
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Dosage forms
The detergent tablet of the invention may be, and
preferably is, formulated for use as a complete
heavy-duty fabric washing composition. The consumer
does not need to use a mix of tablets having different
compositions.
Although one tablet may contain sufficient of all
the components to provide the correct amount required for
an average washload, it is convenient if each tablet
contains a submultiple quantity of the composition
required for average washing conditions, so that the
consumer may vary the dosage according to the size and
nature of the washload. For example, tablet sizes may be
chosen such that two tablets are sufficient for an
average washload; one or more further tablets may be
added if the washload is particularly large or soiled;
and one only tablet may be used if the load is small or
only lightly soiled.
Alternatively, larger subdivisible tablets
representing a single or multiple dose may be provided
with scorings or indentations to indicate unit dose or
submultiple unit dose size to the consumer and to provide
a weak point to assist the consumer in breaking the
tablet if appropriate.
The size of the tablet will suitably range from 10
to 160 g, preferably from 15 to 60 g, depending on the
wash conditions under which it is intended to be used,
and whether it represents a single dose, a multiple dose
or a submultiple dose.
The tablet may be of any suitable shape, but for
manufacturing and packaging convenience is preferably of
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uniform cross-section, for example, circular (preferred)
or rectangular.
EXAMPLES
The following non-limiting Examples illustrate the
invention. Parts and percentages are by weight unless
otherwise stated. Examples identified by numbers are win
accordance with the invention, while Examples identified
by letters are comparative.
Example 1. Comparative Example A
(i) Prearation of bleach composition
A 40 wt% solution of Analar sodium carbonate was
prepared. Acrylic/maleic copolymer in sodium salt form
- Sokalan (Trade Mark) CP5 ex BASF - was admixed in an
amount of 2 wt% based on the sodium carbonate (dry
weight), and the solution was stirred at 50C for
2 hours. The solution was then spray-dried using
laboratory equipment (inlet temperature 275C, feed rate
10 ml/min through a 0.75 mm jet) to give granular
anhydrous sodium carbonate of high specific surface area.
A bleach composition was then prepared by dry-mixing
equal weights of the spray-dried sodium carbonate
composition and sodium percarbonate.
(ii) Preparation of detergent base composition
A detergent base composition was prepared to the
formulation shown in Table 1, by spray-drying an aqueous
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slurry of all ingredients except the nonionic surfactant
3EO which was subsequently sprayed on.
(ii) Tabletting
Tablets were prepared using an Instron (Trade Mark)
Model 4202 Materials Testing Machine fitted with a lOkN
load cell. The machine was operated at its maximum speed
of 100 mm/min and at a pressure of 0.14 kN/cm2 (1.4 MPa).
For Example 1 (the invention), bleach composition
(10 g) was added to the die, the die was tapped gently to
level the powder, and detergent base composition (30 g)
was added on top of the bleach composition, before
tabletting.
For Comparative Example A, the same weights of
bleach composition and detergent composition as in
Example 1 were mixed together, and the mixture added to
the die for tabletting.
The tablets each weighed 40 g, and were 53 mm in
diameter and 22 mm in thickness.
(iii) Storage
The tablets were stored under two sets of
conditions: at 37C/70% relative humidity, and at
28C/70% relative humidity. The storage regime was
deliberately chosen to be as adverse as possible: the
tablets, totally unprotected by any packaging, were
placed standing on edge and separated from one another so
as to expose the maximum possible surface area to the
atmosphere.
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(iv) Dissolution tests
Dissolution testing was carried out in a Miele
(Trade Mark) 756 front-loading automatic washing machine,
using the 40C wash cycle without a washload:
dissolution was monitored using a conductivity cell. The
results are given as the times taken, to the nearest
minute, for 50 wt% and 90 wt% dissolution to take place.
The results are shown in Table 2.
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Table 1: Detergent Base and Tablet Compositions
parts % (tablet)
Detergent base composition
Linear alkylbenzene sulphonate6.00 7.16
Nonionic surfactant (7E0) 2.75 3.28
Soap 1.65 1.97
Zeolite 4A (anhydrous basis) 24.00 28.64
Polymer (acrylic/maleic) 4.00 4.77
Sodium alkaline silicate 0.46 0.55
Sodium carbonate 8.13 9.70
Sodium carboxymethylcellulose0.50 0.60
Fluorescer 0.19 0.23
EDTA 0.20 0.24
Salts, moisture 10.72 12.79
Nonionic surfactant 3EO 4.25 5.07
62.85 75.00
Tablet Composition
Detergent base composition 30.0
Sodium percarbonate 5.0 12.5
Spray-dried sodium carbonate 5.0 12.5
40.00 100.0
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Table 2: Dissolution Results
(i) 28C/70% relative humidity
Storage time Example 1 Exam~le A
(weeks) 50% 90% 50% 90%
1 2 9 10 30
2 2 9 15 25
4 3 12 20 >30
6 3 17 25 >30
(ii) 37C/70% relative humidity
Storage time Example 1 Exam~le A
(weeks) 50% 90% 50% 90%
2 2 12 8 23
4 4 14 8 27
6 Tablets disintegrated during storage
(v) Bleach stability
Percarbonate storage stability was determined by
available oxygen titration using potassium permanganate,
the results being expressed as residual available oxygen
as a molar percentage of the theoretical value.
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The results are shown in Table 3.
Table 3: Percarbonate storage stability
(i) 28C/70% relative humidity
Storage time Remaining available oxygen (mole %)
(weeks)
Example 1Example A
0 100 100
1 91 59
2 83 22
4 70 2
6 68 0
8 63 0
(ii) 37C/70% relative humidity
Storage time Remaining available oxygen (mole %)
(weeks)
Example 1 Example A
0 100 . 100
2 75 20
4 50 0
6 48 o
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Exam~les 2 and 3
(i) Preparation of bleach composition
Example 2
Burkeite was made by spray-drying a mixture of sodium
carbonate, sodium sulphate and Sokolan (Trade Mark) CP5
as described in EP 221776 (Unilever).
A bleach composition was then prepared by dry-mixing
equal weights of the spray-dried Burkeite composition and
sodium percarbonate.
Example 3
Spray dried sodium carbonate/Sokolan (Trade Mark) CP5 was
prepared as in Example 1.
A bleach composition was then prepared by dry-mixing
equal weights of the spray-dried sodium carbonate
composition and sodium percarbonate.
(ii) Preparation of detergent base comPosition
A detergent base composition was prepared to the
formulation shown in Table 4, by spray-drying on aqueous
slurry of all the ingredients except the nonionic
surfactant 3EO which was subsequently sprayed on and the
PAS noodles which were posed-dosed.
(iii) Tablettinq
As for Example 1.
(iv) Storage
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As for Example 1.
Table 4. Detergent Base and Tablet Composition
Parts % ftablet)
Detergent base com~osition
Nonionic surfactant (7EO) 4.5 3.95
Zeolite 4A 37.0 32.45
Polymer (acrylic/maleic) 5.0 4.39
Sodium carbonate 14.9 13.07
Sodium carboxymethyl cellulose 0.5 0.44
Fluorescer 0.2 0.18
Moisture 11.0 9.65
Nonionic surfactant (3EO) 4.0 3.50
PAS Noodles 8.4 7.37
85.5 75.00
Tablet Composition
Detergent Base Composition 30.0
Sodium percarbonate 5.0 12.5
Spray-dried Burkeite (Example 2) or 5.0 12.5
Sodium carbonate (Example 3) ---- -----
100
(v) Bleach Stability
Percarbonate storage stability was determined as in
Example 1.
The results are shown in Table 5.
2053~34
- 26 - C3391
Table 5. Percarbonate Stora~e Stability
(i) 28C/70% relative humidity
Storage time Remaining available oxygen (mole %)
(Weeks)
Example 2 Example 3
0 100 100
2 70 83
4 71
(ii) 37C/70% relative humiditY
Storage time Remaining available oxygen (mole %)
(Weeks)
Example 2 Example 3
0 100 100
2 71 77
4 72 38
23
