Note: Descriptions are shown in the official language in which they were submitted.
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ENCAPSULATED BLEACH PARTICLES
Field of the invention
This invention is concerned with encapsulated bleach
particles having a solid core material, which remain stable
for use in liquid and granular detergent cleaning products.
A method for producing said encapsulated particles is also
disclosed.
Backctround of the invention
It is well known in the detergent art to protect sensitive
solid constituents of a detergent formulation, such as
bleach components, from an incompatible environment by
separating them physically from their environment, for
example by encapsulation.
Bleach particles have been coated with a variety of
materials. In US-A-3,908,045 (Alterman et al), bleach
particles are disclosed which are coated with fatty acids,
polyvinyl alcohol or polyethylene glycols. Other known
coating materials include polymer latex (US-A-4,759,956);
polycarboxylate materials (US-A-4,762,637); polyethylene
waxes of melting point 50-65 C (EP-A-132,184); and various
waxes (US-A-4,421,669).
Since the improved bleach stability as a result of
conventional coatings often appeared to be insufficient,
attempts have been made to improve said stability of
,
encapsulated bleach particles by applying a second coat.
However, these known encapsulation methods often produce
encapsulates which are still incapable to standing up to
long-term storage and/or are too expensive to be
commercially viable.
A further potential problem with the known systems is that
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the encapsulating materials providing the protection may
themselves have an adverse interaction with the bleach
components to be protected.
As an alternative to these encapsulation techniques, WO-A-
94/12613 discloses a method of protecting a bleach component
by dissolving said component in a biopolymer, resulting in a
particulate bleach product comprising a molecular solid
solution of the bleach in the biopolymer.
However, this method was found to be less suitable for those
bleach components which are typically present in a detergent
composition, in amounts of more than 5o by weight based on
the composition.
One object of the invention is to provide a single coat
encapsulated bleach particle which has improved stability to
degradation by other components of the formulation in which
this type of particle is present, by humidity, high
temperature or aqueous liquid media.
An other object is to provide a particulate encapsulated
bleach having a coat with good solubility characteristics
such that the bleach material is released in a controlled
way during the wash.
A further object of the invention is to provide an
encapsulation process which is free of organic solvents that
lead to environmental pollution problems.
A still further object is to provide an encapsulated bleach
material which does not interact unfavourably with fabrics.
It was surprisingly found that these and other objects could
be achieved when a gelled polymer material is used as
coating film for the bleach. Thus coated detergent bleach
particles were found to have both good stability and
excellent solubility characteristics, which was not expected
since gelled polymers, such as gelled alginate, used in the
food industry are known to lack solubility.
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Definition of the invention
Accordingly, in a first aspect the present invention
provides an encapsulated bleach particle, comprising
(a) 1-30% by weight of a coating comprising
an alginate wherein at least 10% by weight of said alginate
is cross-linked with alkaline earth metal ions;
(b) 99-70% by weight of a core material selected from
the group consisting of a peroxygen bleach compound, a
bleach catalyst, and a peroxygen bleach precursor.
In a second aspect, the invention provides a bleaching
detergent composition, comprising surfactant material,
builder material and encapsulated bleach particles according
to the present invention, the concentration of these
particles in said composition being preferably in the range
of 2-40%, more preferably 2-30% by weight.
Detailed description of the invention
The coating
The alginate (a gelled polymer) is present in the coating at
a level of preferably 20-100% by weight, more preferably 50-
100% by weight, the other coating constituents being usual
coating materials known per se.
For obtaining favourable results in respect of storage
stability and solubility characteristics, at least 10% by
weight of the gelled polymer is preferably cross-linked with
alkaline earth metal ions. More preferably, at least 30% by
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weight of the gelled polymer is cross-linked in this way.
Calcium ions are preferred for use as cross-linking alkaline
earth metal ions.
For the alginate polymer material, the phenomena of cross-
linking resulting in gelling can be understood as follows.
Ca2+-ions are known to bind salts of alginic acid. Alginic
acid polymers consist of mannuronic and guluronic acid
segments. It is believed that the gel forming ability is
related primarily to the sequencing of guluronic segments in
the alginic acid polymer. The Na+-ion in the sodium salt of
alginic acid allows replacement of itself with divalent
calcium ions, which form bridges necessary to bind different
polymer segments and obtain the above-mentioned sequencing.
The extent to which said binding of polymer segments has
taken place can be estimated by measuring the ratio of Ca2+
to Na+ ions in the cross-linked sample. On this basis, the
degree (x) of cross-linking of the alginate material is
defined as follows:
2 Ca2+
x = --------------
2 Ca2+ + Na+
It was found that manipulating the degree of cross-linking
provides a powerful tool for controlling the properties of
25' the encapsulated particles of the invention.
The coating is desirably coherent and uniform.
When used in detergent powders, the encapsulated particles
of the invention have a mean particle size of generally 200
- 2500 microns, preferably 500 - 1500 m.
When used in detergent liquid formulations, the encapsulated
particles of the invention generally have a mean particle
size in between 10 and 200 m.
It is essential that the mean particle size of these
particles is such that segregation is avoided when they are
present in a fully formulated composition. The coating of
the encapsulated particles of the invention consitutes
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preferably 1-20t by weight, more preferably 1-10% by weight
of the final particle (i.e. core plus coating).
Core materials
5 The solid core of the particle of the present invention
preferably constitutes 70-99%, more preferably 90-80o by
weight of this particle. The core materials are selected
from the group consisting of a peroxygen bleach compound, a
bleach catalyst and a bleach precursor. All these core
materials are unstable in aqueous or humid environment and
will lose activity without a coating.
Some of the core materials may be obtained commercially in a
form which meets preferred physical characteristics with
respect to size and shape thereof. The preferred shape is
spherical or as close to this geometry as possible.
Many of the other active core materials which may be
suitably used in the encapsulated particle of the present
invention are not commercially available with these
preferred characteristics. It is then beneficial to produce
composite core particles consisting of the active core
ingredient and an agglomerating agent. The agglomerating
agent must be stable and inert with respect to the active
core material. Optionally, an inert material meeting the
same specifications as the agglomerating agent may be added
to the agglomerated core particles.
Bleaching agent
The peroxy bleaching agent
The peroxy bleaching agents may be effectively used as core
material for the particle of the invention.
In the context of the invention, these agents are preferably
= compounds which are capable of yielding hydrogen peroxide in
aqueous solution. Hydrogen peroxide sources are well known
in the art. They include the alkali metal peroxides, organic
peroxides such as urea peroxide, and inorganic persalts,
such as the alkali metal perborates, percarbonates,
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perphosphates persilicates and persulphates. Mixtures of two
or more such compounds may also be suitable.
Particularly preferred are sodium perborate tetrahydrate 5 and, especially,
sodium perborate monohydrate. Sodium
perborate monohydrate is preferred because of its high
active oxygen content. Sodium percarbonate may also be
preferred for environmental reasons.
Alkylhydroxy peroxides are another class of suitable peroxy
bleaching agents. Examples of these materials include cumene
hydroperoxide and t-butyl hydroperoxide.
Organic peroxyacids are a further class of peroxy bleaching
agents which may be used as bleach core. Such materials
normally have the general formula:
/0
H00 C R Y
wherein R is an alkylene or substituted alkylene group
containing from 1 to about 20 carbon atoms, optionally
having an internal amide linkage; or a phenylene or
substituted pYienylene group; and Y is hydrogen, halogen,
alkyl, aryl, an imido-aromatic or non-aromatic group, a COOH
or
0
C OOH
group or a quaternary ammonium group.
Typical monoperoxy acids useful herein include alkyl peroxy
acids and aryl peroxy acids, for example:
(i) peroxybenzoic acid and ring-substituted peroxybenzoic
acids, e.g. peroxy-cx-naphthoic acid;
(ii) aliphatic, substituted aliphatic and arylalkyl
_ _.. _.. ..__. . . ... _. _. _ t
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monoperoxyacids, e.g. peroxylauric acid, peroxystearic acid
and N,N-phthaloylaminoperoxy caproic acid (PAP); and
(iii) 6-octylamino-6-oxo-peroxyhexanoic acid.
Typical diperoxyacids useful herein include, for example:
(iv) 1,12-diperoxydodecanedioic acid (DPDA);
(v) 1,9-diperoxyazelaic acid;
(vi) diperoxybrassilic acid; diperoxysebasic acid and
diperoxyisophthalic acid;
(vii) 2-decyldiperoxybutane-l,4-diotic acid;
(viii) 4,4'-sulphonylbisperoxybenzoic acid; and
(ix) N,N'-Terephthaloyl-di(6-aminoperoxycaproic acid)
(TPCAP).
Inorganic peroxyacid compounds may also be suitable as cores
for the particles of the present invention. Examples of
these materials are salts of monopersulphate, such as
potassium monopersulphate-(MPS).
All these peroxy compounds may be utilized alone or in
conjunction with a peroxyacid bleach precursor and/or an
organic bleach catalyst not containing a transition metal.
Bleach Catalysts
25. Bleach catalysts are also suitable as the core material of
the present invention. Such suitable catalysts include a
manganese (II) salt compound as described in US-A-4,711,748.
Other suitable catalysts, e.g. sulfonimine compounds, are
described in US-A-5,041,232 issued to Batal et al. The
catalysts may be admixed with, or adsorbed upon other
compatible ingredients. Product formulations containing
encapsulated bleach catalysts of the present invention may
also contain a bleaching agent whose action is to be
catalyzed. That bleaching agent may also be optionally
encapsulated according to the present invention.
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Peroxygen Bleach Precursors
Peracid precursors, preferably in granular form, are also
suitable as cores for the particles of the present
invention. Peracid precursors are compounds which react in
the bleaching solution with hydrogen peroxide from an
inorganic peroxygen source to generate an organic peroxy
acid. They are also susceptible to hydrolysis, and cannot
normally be formulated directly into aqueous cleaning
compositions. Peracid precursors, encapsulated according to
the present invention, would be incorporated into products
along with a source of hydrogen peroxide, which also could
optionally be encapsulated according to the present
invention.
Peracid precursors for peroxy bleach compounds have been
amply described in the literature, including in British
Patent Nos. 836,988; 855,735; 907,356; 907,358; 907,950;
1,003,310 and 1,246,339; US-A-3,332,882 and US-A-4,128,494;
and Canadian Patent No. 844,481.
Typical examples of precursors are polyacylated alkylene
diamines, such as N,N,N',N'-tetraacetylethylene diamine
(TAED) and N,N;N',N'-tetraacetylmethylene diamine (TANID);
acylated glycolurils, such as tetraacetylglycoluril (TAGU);
triacetylcyanurate, sodium sulphophenyl ethyl carbonic acid
ester, sodium acetyloxybenzene sulfonate (SABS), sodium
nonanoyloxybenzene sulfonate (SNOBS) and choline sulfophenyl
carbonate.
Peroxybenzoic acid precursors are known in the art, e.g.,
from GB-A-836988. Examples thereof are phenylbenzoate;
phenyl p-nitrobenzoate; o-nitrophenyl benzoate; o-
carboxyphenyl benzoate; p-bromophenyl benzoate; sodium or
potassium benzoyloxybenzenesulfonate; and benzoic anhydride.
Preferred peroxygen bleach precursors for use in the
particle according to the present invention, are sodium-4-
benzoyloxy benzene sulphonate (SBOBS); N,N,N'N'-tetraacetyl
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ethylene diamine (TAED); sodium-l-methyl-2-benzoyloxy
benzene-4-sulphonate; sodium-4-methyl-3-benzoyloxy benzoate;
2-(N,N,N,-trimethyl ammonium) ethyl sodium-4-sulphonphenyl
carbonate chloride (SPCC); trimethyl ammonium toluyloxy-
benzene suiphonate; sodium nonanoyloxybenzene sulphonate
(SNOBS); sodium 3,5,5-trimethyl hexanoyloxybenzene
sulphonate (STHOBS); and the substituted cationic nitriles.
TAED is the most preferred bleach precursor.
The process of producing the coated particles
Preferably, the process of the invention comprises the steps
of -
(i) atomizing an aqueous suspension containing both the
polymer to be gelled and the core material;
(ii) gelling the thus obtained droplets; and
(iii) drying the gelled droplets to form dry free-flowing
particles.
To obtain the best results with regard to homogeneity and
uniformity of the particles to be obtained, these steps are
desirably carried out sequentially, without interruption.
As a first step of said preferred process for producing the
coated particles of the invention, an aqueous suspension
containing both the polymer to be gelled and the core
material is atomized. Atomization techniques are well-known
in the art. Favourable results have been obtained when
atomization is carried out by applying mechanical
disturbance to a streaming aqueous suspension of the polymer
to be gelled and the core material. In a specific example,
mechanical disturbance is achieved by applying resonating
nozzles. This technique offers the advantage of tight
control of particle size distribution while retaining a good
potential for scale-up of the process. Other atomization
techniques are those in which use is made of one-phase
nozzles, two-phase nozzles, and spinning discs.
The gelling step is preferably performed in a bath
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containing alkaline earth metal ions or in a falling film
reactor. The drying step is preferably carried out in a ~
fluid bed.
5 The surface-active material
The bleaching detergent composition according to the
invention generally contains surface-active material in an
amount of from 10 to 501; by weight. Said surface-active
material may be naturally derived, such as soap, or a
10 synthetic material selected from anionic, nonionic,
amphoteric, zwitterionic, cationic actives and mixtures
thereof. Many suitable actives are commercially 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.
Typical synthetic anionic surface-actives 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 aryl radicals. Examples of
suitable synthetic anionic detergent compounds are sodium
and ammonium alkyl sulphates, especially those obtained by
sulphating higher (C$-C18) alcohols produced, for example,
from tallow or coconut oil; sodium and ammonium alkyl (C9-
Clo) benzene sulphonates, particularly sodium linear
secondary alkyl (Cio-C1s) benzene sulphonates; sodium alkyl
glyceryl ether suiphates, especially those ester of the
higher alcohols derived from tallow or coconut oil fatty
acid monoglyceride sulphates and sulphonates; sodium and
ammonium salts of sulphuric acid esters of higher (C9-C1$)
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 ammonium salts
of fatty acid amides of methyl taurine; alkane
monosulphonates such as those derived by racting alpha-
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olefins (C8-C20) with sodium bisulphite and those derived by
reaction paraffins with SO2 and C12 and then hydrolysing with
a base to produce a random sulphonate; sodium an ammonium
C7-C12 dialkyl sulphosuccinates; and olefin sulphonates which
term is used to describe material made by reacting olefins,
particularly C10-C20 alpha-olefins, with SO3 and then
neutralising and hydroysing the reaction product. The
preferred anionic detergent compounds are sodium (Clo-C1s)
alkylbenzene sulphonates, sodium (C16-C18) alkyl ether
sulphates.
Examples of suitable nonionic surface-active compounds which
may be used, preferably together with the anionic surface-
active compounds, include, in particular, the reaction
products of alkylene oxides, usually ethylene oxide, with
alkyl (C6-C22) phenols, generally 5-25 EO, i.e. 5-25 units of
ethylene oxides per molecule; and the condensation products
of aliphatic (C$-C18) primary or secondary linear or branched
alcohols with ethylene oxide, generally 2-30 EO. Other so-
called nonionic surface-actives include alkyl
polyglycosides, sugar ester, long-chain tertiary amine
oxides, long-chain tertiary phosphine oxides and dialkyl
sulphoxides.
25*Amphoteric or zwitterionic surface-active compounds can also
be used in the composition of the invention but this is not
normally desired owing to their relatively high cost. If any
amphoteric or zwitterionic detergent compounds are used, it
is generally in small amounts in compositions based on the
much more commonly used synthetic anionic and nonionic
actives.
The bleaching detergent composition of the invention will
preferably comprise from 1-15 % wt of anionic surfactant and
from 10-40 1; by weight of nonionic surfactant.
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The deteraency builder
The bleaching detergent composition of the invention
normally and preferably also contains a detergency builder
in an amount of from about 5-80 ~k by weight, preferably from
about 10-60% by weight.
Builder materials may be selected from 1) calcium
sequestrant materials, 2) precipitating materials, 3)
calcium ion-exchange materials and 4) mixtures thereof.
Examples of calcium sequestrant builder materials include
alkali metal polyphosphates, such as sodium
tripolyphosphate; nitrilotriacetic acid and its water-
soluble salts; the alkali metal salts of carboxymethyloxy
succinic acid, ethylene diamine tetraacetic acid,
oxydisuccinic acid, mellitic acid, benzene polycarboxylic
acids, citric acid; and polyacetal carboxylates as disclosed
in US-A-4,144,226 and US-A-4,146,495.
Examples of precipitating builder materials include sodium
orthophosphate and sodium carbonate.
Examples of calcium ion-exchange builder materials include
the various types of water-insoluble crystalline or
amorphous aluminosilicates, of which zeolites are the best
known representatives, e.g. zeolite A, zeolite B (also know
as Zeolite P), zeolite C, zeolite X, zeolite Y and also the
zeolite P type as described in EP-A-0,384,070.
In particular, the compositions of the invention may contain
any one of the organic and inorganic builder materials,
though, for environmental reasons, phosphate builders are
preferably omitted or only used in very small amounts.
Typical builders usable in the present invention are, for
example, sodium carbonate, calcite/carbonate, the sodium
salt of nitrilotriacetic acid, sodium citrate,
carboxymethyloxy malonate, carboxymethyloxy succinate and
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the water-insoluble crystalline or amorphous aluminosilicate
builder material, each of which can be used as the main
builder, either alone or in admixture with minor amounts of
other builders or polymers as co-builder.
it is preferred that the composition contains not more than
5 s by weight of a carbonate builder, expressed as sodium
carbonate, more preferable not more than 2.5 %- by weight to
substantially nil, if the composition pH lies in the lower
alkaline region of up to 10.
Other ingredients
Apart form the components already mentioned, the bleaching
detergent composition of the invention can contain any of
the conventional additives in amounts of which such
materials are normally employed in fabric washing detergent
compositions. Examples of these additives include buffers
such as carbonates, lather boosters, such as alkanolamides,
particularly the monoethanol amides derived from palmkernel
fatty acids and coconut fatty acids; lather depressants,
such as alkyl phosphates and silicones; anti-redeposition
agents, such as sodium carboxymethyl cellulose and alkyl or
substituted alkyl cellulose ethers; stabilizers, such as
phosphonic acid derivatives (i.e. Dequest types); fabric
softening agents; inorganic salts and alkaline buffering
agents, such as sodium sulphate, sodium silicate etc.; and
usually in very small amounts, fluorescent agents; perfumes;
enzymes, such as proteases, cellulases, lipases, amylases
and oxidases; germicides and colourants.
Of the additives, transition metal sequestrants, such as
EDTA and the phosphonic acid derivatives, e.g. ethylene
diamine tetra-(methylene phosphonate)-EDTMP- are of special
importance, as not only do they improve the stability of
sensitive ingredients, such as enzymes, fluorescent agents,
perfumes and the like, but also improve the bleach
performance, especially at the higher pH region of above 10,
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particularly at pH 10.5 and above.
A highly desirable additive ingredient with multi-functional
characteristics in detergent compositions is from 0.1 s to
about 3%- by weight of a polymeric material having a
molecular weight of from 1,000 to 2,000,000 and which can be
a homo- or co-polymer of acrylic acid, maleic acid, or salt
or anhydride thereof, vinyl pyrrolidone, methyl- or
ethylvinyl ethers, and other polymerizable vinyl monomers.
Preferred examples of such polymeric materials are
polyacrylic acid or plyacrylate; polymaleic acid/acrylic
acid copolymer; 70-30 acrylic acid/hydroxyethyl maleate
copolymer; 1:1 styrene/maleic acid copolymer;
isobutylene/maleic acid and diisobutylene/maleic acid
copolymers; methyl- and ethylvinylether/maleic acid
copolymers; ethylene/maleic acid copolymer; polyvinyl
pyrrolidone; and vinyl pyrrolidone/maleic acid copolymer.
The bleaching detergent composition of the invention can be
formulated in any suitable form, such as the powdered or
granulated, the liquid or paste-like form.
When formulated as free-flowing particles, e.g. in powdered
or granulated'form, the bleaching detergent composition can
be produced by any of the conventional techniques employed
in the manufacture of detergent compositions, for instance
by slurry-making, followed by spray-drying to form a
detergent base powder to which the heat-sensitive
ingredients and optionally some other ingredients as desired
can be added as dry substances.
It will thus be appreciated, that the detergent base powder composition, to
which the particles of the present invention
are added, can itself be made in a variety of ways, such as
the so-called part-part processing, non-tower route
processing, dry-mixing, agglomeration, granulation,
extrusion, compacting and densifiying processes etc., such
ways being well known to those skilled in the art and not
forming the essential part of the present invention.
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The following non-limiting examples will more fully
illustrate the embodiments of the invention. All parts and
percentages referred to herein are by weight unless
otherwise indicated.
5 In the Examples the following abbreviations are used:
Manugell DM, : different grades ofsodium alginate, ex
Manugel DH : Kelco international (division of Merck)
Manugel. GMB
10 Protonals"SF120M: Sodium alginate, ex Pronova Biopolymers;
Na-PAS : sodium salt of primary alkyl sulphate;
Nonionic 7E0 : nonionic surfactant; C12-C14 ethoxylated
alcohol containing an average of 7 ethylene
oxide group per molecule, ex ICI;
15 Nonionic 3E0 : nonionic surfactant; C12-C14 ethoxylated
alcohol containing an average of 3 ethylene
oxide groups per molecule, ex ICI;
Soap : sodium salt of stearic acid;
Zeolite A 24 : crystalline sodium aluminosilicate, ex
Crosfield;
Maxacall'CX 600K: enzyme granules, ex Genencor;
',Dequest 2047 : phosphonic acid derivative;
Coated Percarbonate: Boron coated percarbonate, ex Interox
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Examples 1,2. Comparative Example A
TAED alginate granules were prepared using the following
procedure.
900 ml of 1o solution of alginate was made in demi water.
The sodium alginate used ( having tradename Manugel DM) was
obtained from Kelco International. The sodium and calcium
levels in the dry Manugel DM were determined by X-ray
fluorescense to be 7.33% and 0.137% by weight repectively.
The alginate solution was made by intensive mixing using a
very high shear mixer (Ultra Turrax-) and by introducing
the required level-s of alginate slowly.
TAED (ex Hoechst) was subsequently introduced in the thus
prepared alginate solution, while continuing the mixing
operation. Two levels of TAED dispersions were prepared:
171 grams TAED respectively 36 grams TAED in 900 ml of
alginate solution. The TAED had an average particle size of
90 microns and its activity was 97% ( as measured by
volumetric titration).
The thus prepared TAED dispersions (also called: slurries)
were fed to a two-phase nozzle through as presurized vessel.
A small over-pressure was applied to facilitate the flow.
The two-phase nozzle had an internal diameter of 1.0 mm. The
amount of air introduced was regulated to provide droplets
of desired particle size.
The thus atomized droplets were fed into a calcium bath
having a capacity of 1.5 litre. Calcium chloride salt was
used to provide 0.1 M Ca2+ solution. A cross-linking time of
20 minutes was applied before the thus formed wet gelled
granules were removed by filtration. These granules were
subsequently dried in a fluid bed at 70 C for 15 minutes,
and finally sieved to obtain the desired particle size
distribution.
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In addition, for reasons of comparison, a reference sample
of sulphate containing granulated TAED particles was
prepared using a method known per se.
The process conditions applied and the granule compositions
obtained are illustrated in Table 1.
TABLE 1
Example no, 1 2 A
Slurry composition(in t)
water 83.2 95.2
Manugel DM 0.8 1.0
TAED 16.0 3,8
Calcium bath O.1M 0.1M
Dry gelled granule composition(in 20 TAED 88.3 68.3 80.0
sodium 0.65 0.25
calcium 0.93 2.18
alginate 5 15
sulphate 10.0
other filler/binder 7.0
minors/water 5.14 14.27 3.0
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Examples 3 , 4
In these Examples, two solubility tests were carried out
using following particulate detergent base composition:
( s by weight)
Na-PAS 12.68
Nonionic 7E0 8.21
Nonionic 3E0 5.47
soap 2.14
Zeolite A-24 (anhydrous) 44.54
Na citrate 5.89
Light soda ash 3.19
Antifoam granule 5.55
Na bicarbonate 1.38
Maxacal CX 600k 2019 GU/mg 2.08
Moisture, Minors 8.88
The solubility tests were performed in a 1 litre demi water
bath kept at a constant temperature of 40 C.
In the first test, the detergent base composition
illustrated above was used together with a 710-1000 microns
sieve fraction of the coated TAED granules prepared in
Example 1.
The second test was performed without the presence of the
detergent base composition in order to illustrate the effect
of said detergent base composition on the solubility of
alginate-coated TAED granules. In this second test, the same
sieve fraction of the coated TAED granules prepared in
Example 1, was used.
Aqueous wash solutions with compositions as indicated in
Table 2 were prepared and TAED release was measured by
withdrawing 25 ml aliquots from the aqueous wash solutions
after the indicated time periods and determining TAED levels
by standard peracid volumetric titration. The results with
respect to TAED dissolution characteristics are shown in
Table 2.
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TABLE 2
Example no. 3
4
Composition of wash solution (g/1) (g/1)
Detergent base formulation 7.45 -
Coated percarbonate 2.05 2.00
TAED granules (710-1000 microns) 0.5 0.5
Dequest 2047 0.03 0.1
TAED release (in g/1)
after time period (minutes)
5 0.151 0.169
10 0.392 0.278
0.422 0.351
15 20 0.415 0.408
0.417 0.404
0.422 0.406
20 It is thus clearly demonstrated that in the presence of a
standard detergent formulation the coated TAED granules of
the invention have favourable solubility, and that in the
absence of such detergent formulation the TAED-alginate
granules dissolve somewhat more slowly.
Examples 5-7, Comparative Example B
Stability tests were carried out by mixing the detergent
base composition of Example 3 with various TAED-alginate
granules and percarbonate , and storing the thus obtained
mixtures in a climate cell at 37 C and 709.1- humidity during a
period of 4 weeks.
The mixture of Example 5 contained a 710-1400 microns sieve
fraction of the alginate-coated TAED granules prepared in
Example 1.
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The mixtures of Examples 6 and 7 contained a 500-710 microns
~
sieve fraction respectively a 710-1400 microns sieve
fraction of the alginate-coated TAED granules prepared in
Example 2.
5 The mixture of Example B contained a 710-1400 microns sieve
fraction of the sulphate containing TAED granules prepared
in Example A.
The compositions prepared for stability testing and the
10 stability results (i.e. the TAED activity after the
indicated storage periods, in terms of the measured level -
in !k by weight- of TAED in the composition) are shown in
Table 3.
15 TABLE 3
Example no. 5 6 7
Sample Composition (in grams)
20 Detergent base formulation 14.5 14.5 14.5 14.5
coated percarbonate 4.1 4.1 4.1 4.1
TAED-granules, 710-1400 (example 1) 1.3
TAED-granules, 500-710 (example 2) 1.3
TAED-granules, 710-1400 (example 2) 1.3
TAED-granules, 710-1400 (example A) 1.3
Dequest 2047 0.08 0.08 0.08 0.08
TAED activitv (%~TAED)
after storage period (in weeks)
0 5.3 4.1 3.7 4.8
1 5.3 4.0 3.7 4.1
2 4.8 3.6 3.5 2.8
3 4.5 3.3 3.2 2.6
4 4.2 3.0 3.0 2.3
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It can clearly be noticed that alginate-coated TAED granules
have outstanding stability in standard particulate detergent
compositions. Furthermore two remarkable observations can be
made:
(i) very high levels of TAED loadings are possible. The 88%
TAED granules of example 1 were observed to have a higher
stability than the 80's reference granules of Example A. This
can be derived from the above Table 3 when comparing the
stability results of Example 5 with those of Example B;
(ii) when comparing the stability results of Example 6 with
those of Example B, it can be noticed that smaller particle
sizes of particles according to the invention offer
significantly better stability than larger particles of the
prior art.
Examples 8 - 11
These examples illustrate that excellent storage stability
of TAED granules can be obtained when using several
different grades of alginate material as a coating for these
granules.
Four different alginate-coated TAED granules were tested in
this series, the composition of the slurry used for making
these TAED granules being illustrated in Table 4.
TABLE 4
Example no. 8 9 10 11
Slurry composition(in
demin water 83.2 70.8 82.8 83.1
Manugel DM 0.9
Manugel DH 1.45
Manugel GMB 0.85
Protonal SF120M 0.85
TAED 15.9 27.7 16.4 16.1
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The two-phase nozzle assembly as described in Examples 1 and
2 above, was used to atomize this slurry. The internal
diameter of the nozzle was 1.0 mm and an over-pressure of
0.5-0.8 bar was applied to achieve atomization.
The cross-linking step was carried out in a 0.1 M CaC12
solution. A cross-linking time of 10 minutes was applied.
The thus formed wet gelled granules were removed by
filtration and subsequently dried in a fluid bed at 70 C
for 15 minutes. The 500-710 microns sieve fraction was
sieved out from the dried granules and further tested.
The level of TAED in the obtained granules was in the range
of 88-90W by weight.
Solubility and storage tests were performed using the base
composition of example 3 together with coated percarbonate
and the thus obtained TAED granules. The following total
detergent formulations were used for these tests (see Table
5).
TABLE 5
Example 8 9 10 11 C
Total Composition (in %)
Detergent base'composition 73 73 73 73 73
Coated percarbonate 20.5 20.5 20.5 20.5 20.5
TAED granules (500-710 m) 6.5 6.5 6.5 6.5 6.5
It can be seen that Table 5 also shows a comparative example
C relating to a reference composition including sulphate
containing TAED granules having a composition equal to that
of the granules of Example A (see Table 1).
The solubility was tested by dosing 10 grams of the total
detergent compositions shown in Table 5, in a 1 litre demi
water bath kept at a constant temperature of 40 C, for
obtaining aqueous wash solutions. The level of the TAED
released in said solutions was measured as indicated in
Examples 3, 4. The results with respect to TAED dissolution
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characteristics are shown in Table 6, as a percentage of the
TAED initially present in the total detergent compositions.
Table 6
Example no. 8 9 10 11 C
TAED-release (in W)
after time-period (minutes)
5 96.4 90.8 74.2 75.1 98.9
10 100.0 100.0 98.9 100.0 95.0
99.5 94.6 97.4 98.9 96.1
97.4 96.2 100.0 97.9 91.0
The storage stability of the total compositions shown in
15 Table 5 was measured by storing 20 grams of said
compositions in plastic cups having a perforated lid and
placed in a climate cell at 37 C and 70% humidity.
Periodically, the cups were removed and the compositions
contained therein titrated, for determining remaining active
20 TAED levels. The stability results results (i.e. the TAED
activity remaining after the indicated storage periods,
expressed as a percentage of the TAED initially present in
the compositions) are shown in Table 7.
Table 7
Example no. 8 9 10 11 C
TAED activity (1~)
after storage period (weeks)
0 100 100 100 100 100
1 92.5 95.8 96.8 93.2 93.4
2 82.5 90.4 87.0 79.0 79
3 74.7 85 81.3 71.2 67.5
4 63.1 77 73.9 64.9 48.8
It can be seen that the alginate coated TAED granules
exhibit a higher stability than the sulphate containing
granules of the prior art.
