Note: Descriptions are shown in the official language in which they were submitted.
WO 94!15010 21~~~84 PCT/US93/06818
1
COATED PEROXYACID BLEACH PRECURSOR COMPOSITIONS
Technical Field
This invention relates to solid peroxy acid bleach
precursor particles and to particulate detergent
compositions incorporating inorganic perhydrate bleaches
together with N- or o- acyl group - containing
peroxycarboxylic acid bleach precursors (so-called bleach
activators).
Back4round of the Invention
Bleach precursor compositions have come into widespread
use in recent years as heavy duty fabric cleaning
products, particularly in automatic washing machines. The
growth in usage of bleach activators has mirrored a
decrease in fabric wash temperatures which itself has
WO 94/15010 ~ '141584 PCT/US93/06818
2
accompanied an increase in the proportion of fabrics that
are coloured.
One problem that has become more significant as a result
of these trends is that of damage to fabric colours and
materials caused by the development of localised high
concentrations of bleaching species. High bleach
concentrations can arise around any particulate bleaching
species for several reasons. The bleaching species may
itself have an intrinsically low solubility, its
solubility may have been hindered by the presence of other
materials such as viscous surfactant phases or the
agitation regime in the immediate environment of the
bleach species may not be high enough to disperse the
dissolved bleach. Where a~ bleach activator forms a
component of the composition the potential problem is
increased. In addition to the potential for localised
high concentrations of perhydroxyl ion arising from
dissolution of the inorganic perhydrate normally contained
in laundry detergent compositions, the perhydrolysis of
the bleach activator to form peroxycarboxyl anions can
give rise to significant localised peroxycarboxylate
bleach concentrations.
The development of so-called concentrated products and
their delivery via dispensing devices placed in the
machine drum together with the fabric load has merely
served to exacerbate these problems. Accordingly a need
exists to provide detergent compositions in which the
bleach activator is incorporated in a form that minimises
and preferably eliminates damage to fabric colours and
materials during its dissolution and perhydrolysis in the
wash liquor.
The prior art contains numerous examples of bleach
activators coated or agglomerated so as to increase their
WO 94115010 PCTIUS93/06818
2.415$4
3
stability on storage in detergent compositions and/or to
influence their solution behaviour.
EP-A-0070474 discloses granulate bleach activators
prepared by spray drying an aqueous pumpable dispersion
containing an N-acyl or O-acyl compound together with at
least one water soluble cellulose ether, starch or starch
derivative in a weight ratio of activator to coating of
from 98:2 to 90:10.
GB-A-1507312 discloses the coating of bleach activators
with a mixture of alkali metal Cg - C22 fatty acid salts
in admixture with the corresponding fatty acids. GB-A-
1381121 employs a molten coating of inter alia C14 - C18
fatty acid mixtures to protect solid bleach activators.
GB-A-1441416 discloses a similar process employing a
mixture of C12 - C14 fatty acids and C10 - C20 aliphatic
alcohols. EP-A-0375241 describes stabilised bleach
activator extrudates in which C5- Clg alkyl peroxy
carboxylic acid precursors are mixed with a binder
selected from anionic and nonionic surfactants, film
forming polymers fatty acids or mixtures of such binders.
EP-A-0356700 discloses compositions comprising a bleach
activator, a water soluble film forming polymer and 2-15%
of a C3-C6 polyvalent carboxylic acid or hydroxycarboxylic
acid for enhanced stability and ease of
dispersion/solubility. The carboxylic acid, of which a
preferred example is citric acid, is dry mixed with the
bleach activator and then granulated with the film forming
polymer. The citric acid is asserted to provide an
enhanced rate of dissolution of the bleach activator
granules.
EP-A-0382464 concerns a process for coating or
encapsulation of solid particles including bleaching
compounds and bleach activators in which a melt is formed
WO 94115010 ~'-4~-J~~ PCTIUS93/06818
4
of coating material in which the particles form a disperse
phase, the melt is destabilised and then caused to crumble
to a particulate material in which the disperse phase
particles are embedded in the continuous (coating) phase.
A variety of coating materials are disclosed and certain
materials such as polyacrylic acid and cellulose acetate
phthalate are taught as being useful where release of the
coated material is dependent on pH.
The overall emphasis in the prior art has thus been on the
protection of the bleach activator against a hostile
environment during storage and relatively little attention
has been paid to the dissolution characteristics of the
coated or agglomerated material in use. Where coating
and/or agglomeration has been~proposed with poorly soluble
materials such as fatty acids, this has resulted in a rate
of perhydrolysis of the bleach activator which is slower
than that which would occur if it had not been so
protected. Any use of more rapidly soluble materials such
as citric acid has been in the context of an agglomerate
component in which more rapid solution of the bleach
activator has been the objective. In both instances,
because perhydrolysis commences as soon as the detergent
product starts to dissolve and form an alkaline hydrogen
peroxide solution the problem of localised peroxy acid
bleach concentrations has remained unsolved.
One solution to this problem would be to delay the start
of perhydrolysis in order to avoid the fabric colour
damage problems associated with the dissolution behaviour
of other detergent product components. However it is
important that perhydrolysis of the bleach precursor and
subsequent dispersion of the peroxycarboxylate bleach is
as rapid-as possible when it commences because of the
short wash times of modern automatic washing machines.
~
21 41 584
The problem that arises in simultaneously satisfying these
two objectives does not appear to have been recognised in
the prior art.
It is known that the rate of perhydrolysis of a
percarboxylic acid bleach precursor in an aqueous
oxidising medium is progressively reduced as the pH of the
medium is reduced, particularly when the pH falls below
the pKa of the parent acid of the precursor leaving group.
However the fatty acids taught as coating agents in the
prior art are not useful as a means of providing a low pH
environment in an aqueous wash liquor because of their
insolubility. Moreover fatty acids used as coating and/or
agglomerating agents for peroxy acid bleach precursors
have been found to reduce the rate of perhydrolysis of the
latter, thereby reducing the effectiveness of the
resultant peroxycarboxylic acid bleach.
Another problem encountered within the compositions of the
prior art relates to the storage and handling properties
of said compositions, and is thus an additional object of
the present invention to provide a bleach precursor
composition as a free-flowable powder which remains as
such throughout prolonged storage time.
WO 92/13798, published August 20, 1992 proposes to use
various water-soluble organic materials, including certain
monomeric and olygomeric carboxylates as coating materials
for such bleach precursor compositions.
In WO 94/03395, applicant described how certain acidic polymeric
materials having certain specified characteristics can be used
as agglomerating and coating materials for peroxy acid bleach
precursors, to delay the onset of perhydrolysis during
dissolution of the product under the constrained agitation
conditions of a loaded washing machine drum without
B
-21 41 584
adversely hindering perhydrolysis when it occurs, and to
provide peroxyacid bleach precursor compositions as a
storage-stable free-flowable powder.
It has further been found that the coated bleach precursor
material described in WO 94/03395 can be improved by
controlling the level of coating as a function of the
particle size. This results in improved bleaching
performance whilst maintaining stability, and safety to
fabric colours. Alternatively, one can use the finding of
the present invention to further reduce fabric damage for
a given bleaching performance.
Summar~r of the Invention
The present invention is directed to a composition
comprising particles of coated peroxyacid bleach
precursor, wherein said composition comprises particles of
different sizes, wherein said precursor comprises one or
more N-, or o- acyl groups and has a Mpt>30°c, wherein
said precursor is coated with a coating material; wherein
said coating material is selected from water-soluble
acidic polymers, wherein said polymers have a water
solubility greater than 5 g/1 at 20°C, a molecular weight
of from 1000 to 250,000, wherein a 1% solution of said
polymer has a pH of less than 7, preferably less than 5.5,
and wherein the level of said coating in said particles is
greater in particles of smaller size. Preferably, said
precursor is co-agglomerated with a said water-soluble
acidic polymer before it is coated.
Detailed Description of the Invention
The compositions of the present invention comprise
particles of coated peroxyacid bleach
B
WO 94115010 ,~~~ S~~ PCT/US93106818
precursor. The compositions according to the present
invention comprise particles of different sizes. All
particles, which can be different or, preferably,
identical as to the specific ingredients they comprise,
comprise a solid peroxyacid bleach precursor, a coating
material and, preferably a binder material.
As a first essential ingredient, the solid peroxyacid
bleach precursor compositions of the present invention
incorporate precursors containing one or more N- or O-
acyl groups, which precursors can be selected from a wide
range of classes. Suitable classes include anhydrides,
esters, imides and acylated derivatives of imidazoles and
oximes, and examples of useful materials within these
classes are disclosed in GB-A-1586789. The most preferred
classes are esters such as are disclosed in GB-A-836988,
864,798, 1147871 and 2143231 and imides such as are
disclosed in GB-A-855735 & 1246338.
Particularly preferred precursor compounds are the N-
,N,N1N1 tetra acetylated compounds of formula
O O
CH3 - C C - CH3
\N - (CH2)x - N
CH3 - C ~ ~ C - CH3
O O
wherein x can be O or an integer between 1 & 6.
Examples include tetra acetyl methylene diamine (TAMD) in
which x=1, tetra acetyl ethylene diamine (TAED) in which
x=2 and tetraacetyl hexylene diamine (TAHD) in which x=6.
These and analogous compounds are described in GB-A-
907356. The most preferred peroxyacid bleach precursor is
TAED.
.,
WO 94/15010 ~"' PCT/US93/06818
214~~~4 _
8
Solid peroxyacid bleach precursors useful in the present
invention have a Mpt>30°C and preferably >40°C. Such
precursors will normally be in fine powder or crystalline
form in which at least 90% by weight of the powder has a
particle size < 150 micrometers.
Another essential ingredient of the compositions according
to the present invention is a water-soluble acidic
polymer. Said polymer is used in the compositions
according to the present invention as the coating material
to coat said precursor. In one embodiment of the present
invention, said precursor is co-agglomerated with a binder
material before it is coated. Said binder material is
preferably but not necessarily also a said water-soluble
acidic polymer. In a preferred embodiment of the
invention the binder material and the coating material are
different water-soluble acidic polymers, but in another,
most preferred embodiment of the present invention, the
binder material and the coating material are the same
water-soluble acidic polymer.
Suitable polymers for use herein are water-soluble. By
water-soluble, it is meant herein that the polymers have a
solubility greater than 5 g/1 at 20°C.
Suitable polymers for use herein are acidic. By acidic,
it is meant herein that a 1% solution of said polymers has
a pH of less than 7, preferably less than 5.5.
Suitable polymers for use herein have a molecular weight
in the range of from 1000 to 280,000, prefereably from
1500 to 150,000, preferably, suitable polymers for use
herein have a melting point superior to 30°C.
~~~~5~4
WO 94!15010 PCTIUS93/06818
9
Suitable polymers which meet the above criteria and are
therefore particularly useful in the present invention,
include those having the following empirical formula I .
R1 yp (-X - CR3-) R2
I
C02M n
wherein X is O or CH2; Y is a comonouer or comonomer
mixture; R1 and R2 are bleach-stable polymer-end groups;
R3 is H, OH or C1_4 alkyl; M is H, and mixtures thereof
with alkali metal, alkaline earth metal, annonium or
substituted ammonium; p is from 0 to 2; and n is at least
10, and mixtures thereof. the proportion of M being H in
such polymers must be such as to ensure that the polymer
is sufficiently acidic to meet the acidity criteria as
hereinbefore defined.
Polymers according to formula I are known in the field of
laundry detergents, and are typically used as chelating
agents, as for instance in GB-A-1,597,756. Preferred
polycarboxylate polymers fall into several categories. A
first category belongs to the class of copolymeric
polycarboxylate polymers which, formally at least, are
formed from an unsaturated polycarboxylic acid such as
malefic acid, citraconic acid, itaconic acid and mesaconic
acid as first monomer, and an unsaturated monocarboxylic
acid such as acrylic acid or an alpha -C1_4 alkyl acrylic
acid as second monomer. Referring to formula I,
therefore, preferred polycarboxylate polymers of this type
are those in which X is CH2, R3 is H or C1_4 alkyl,
especially methyl, p is from about 0.1 to about 1.9,
prefereably from about 0.2 to about 1.5, n averages from
about 10 to about 1500, preferably from about 50 to about
1000, more preferably from 100 to 800, especially from 120
to 400 and Y comprises monomer units of formula II
WO 94115010 ~,a1..~1-5~~ PCTlUS93/06818
CH CH
C02M C02M II
Such polymers are available from BASF under the trade name
Sokalan(R) CP5 (neutralized form) and Sokalan(R) CP45
(acidic form)
A second category belongs to the class of polycarboxylate
polymers in whichm referring to fromula I, X is CH2, R3 is
OH, p is from 0 to 0.1, preferably 0 and n averages from
about 50 to about 1500, preferably from about 100 to 1000.
Y, if present, can be a polycarboxylic acid such as II
above, or an ethylene oxide moiety.
A third category belongs to the class of acetal
polycarboxylate polymers in which, referring to formula I,
X is ) , R3 is H, p is from 0 to 0. l, preferably 0 and n
averages from 10 to 500. If present, Y again can be a
polycarboxylic acid such as II above or an ethyleneoxide
moiety.
A fourth category belongs to the class of polycarboxylate
polymers in which referring to fromula I, X is CH2, R3 is
H or C1_4 alkyl, p is 0 and n averages from about 10 to
1500, preferably from about 500 to 1000.
A fifth category of polycarboxylate polymers has the
formula I in which X is CH2, R3 is H or C1-4 alkyl,
especially methyl, p is from 0.01 to 0.09, preferably from
0.02 to 0.06, n averages from about 10 to about 1500,
preferably from about 15 to about 300 and Y is a
polycarboxylic acid formed from malefic acid, citraconic
acid,m itaconic acid or mesaconic acid, highly preferred
being malefic acid-derived comonomers of formula II above.
-- WO 94J15010 ~1~~~8q PCTIUS93J06818
11
The bleach-stable polymer end groups in formula I suitably
include alkyl groups, oxyalkyl groups and alkyl carboxylic
acid groups and salts and esters thereof.
In formula I above, M is H or mixtures thereof with alkali
metal, alkaline earth metal, ammonium or substituted
ammonium. The proportion of M which is H is such as to
ensure that the polymer meets the pH criteria described
herein above.
In the above, n, the degree of polymerization of the
polymer can be determined from the weight average polymer
molecular weight by dividing the latter by the average
monomer molecular weight. Thus, for a malefic-acrylic
copolymer having a weight average molecular weight of
15,500 and comprising 30 mole % of malefic acid derived
units, n is 182 (i.e. 15,500/(116 x 0.3 + 72 x 0.7).
In case of doubt, weight-average polymer molecular weights
can be determined herein by gel permeation chromotography
using Water [mu] Porasil (RTM) GPC 60 A2 and [mu] Bondagel
(RTM) E-125, E-500 and E-1000 in series, temperature-
controlled columns at 40°C against sodium polystyrene
sulphonate polymer standards, available from Polymer
Laboratories Ltd., Shropshire, UR, the polymer standards
being 0.15M sodium dihydrogen phosphate and 0.02M
tetramethyl ammonium hydroxide at pH 7.0 in 80/20
water/acetonitrile.
Mixtures of polycarboxylate polymers are also suitable
herein, especially mixtures comprising a high molecular
weight component having an n value of at least 100,
preferably at least 120, and a low molecular weight
component having an n value of less than 100, preferably
from 10 to 90, more preferably from 2o to 80. Such
mixtures are optimum from the viewpoint of providing
excellent bleach stability and anti-incrustation
WO 94/15010 ~~4~J~~ PCT/US93/06818
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performance in the context of a zerophosphate detergent
f ormula .
In mixtures of this type, the weight ratio of high
molecular weight component to low molecular weight
component is generally at least 1:1, preferably from about
1:1 to about 20:1, more preferably from about 1.5:1 to
about 10.1, especially from about 2:1 to about 8:1.
Preferred polycarboxylate polymers of the low molecular
weight type are polycarboxylate polymers of the fourth
category (homopolyacrylate polymers) listed above.
Of all the above, highly preferred polycarboxylate
polymers herein are those of the first category in which n
averages from 100 to 800, preferably from 120 to 400 and
mixtures thereof with polycarboxylate polymers of the
fourth category in which n averages from 10 to 90,
preferably from 20 to 80.
Other suitable polymers for use herein include polymers
derived from amino acids such as polyglutamine acid, as
disclosed in co-pending application GB 91-20653.2, and
polyaspartic acid, as disclosed in EP 305 282, and EP 351
629.
The particles in the compositions according to the present
invention comprise from 30% to 93 % by weight of the total
composition of said peroxyacid bleach precursor,
preferably from 70% to 88%. Furthermore, the particles in
the compositions according to the present invention
comprise from 7% to 70% by weight of the total composition
of said binding agent, preferably from 12% to 30%.
The composition according to the invention comprises
particles described hereinabove of different size.
Another essential feature of the present invention is that
WO 94/15010 2~~~s$L~ PCTIUS93/06818
13
the level of coating should be greater in the smaller
particles than in the bigger particles.
Particles of different sizes in the composition of the
present invention can be separated by using sieves. The
compositions according to the present invention comprise
particles of from 100 micrometers to 1700 micrometers, i.e
all particles which pass through a sieve of 1700
micrometer and and which do not pass through a sieve of
100 micrometer. Smaller and bigger particles are not
suitable for the purpose of the present invention.
The composition according to the present invention can be
separated in at least two classes, each class comprising
particles within a size range. For each class, the mean
coating level can be determined. Compositions according
to the present invention are those where the mean coating
level is greater for the particles belonging to the class
of smaller particle size.
For each particle size class, the mean coating level, as
used herein, is the amount of coating material eicpressed
in weight % based on the total weight of the particles in
the class, i.e. the mean coating level does not take into
account the differences in particle sizes within a given
class. As used herein, the mean coating level of the
composition according to the present invention is the
amount of coating material, expressed in weight $, based
on the total weight of the composition.
Depending on the polymer used for agglomeration and
coating in the compositions according to the present
invention, different analytical means can be used to
measure the amount of polymer in the particles, thus the
coating level. Such means include colorimetric tritration
with ferrothiocyanate, photometric titration with
chromotropes, gas chromatography, etc. A preferred and
WO 94/15010
PCT/US93/06818
19
simple method is an acid-base titration calibrated with
the polymer. In the preferred embodiment of the present
invention where the binder material and the coating
matetial are the same polymer, the coating level can be
determined by measuring the amount of polymer in an
agglomerated but uncoated sample, measuring the amount of
polymer in an agglomerated and coated sample of same
weight, then calculating the difference between both
samples. Suitable compositions herein have a mean coating
level of from 2% to 25%, preferably 5% to 20%, most
preferably 5% to 15%.
Preferred composition herein can be splitted in particles
belonging to three classes.
A first class comprises particles of from 1700 to 850
micrometers. Particles of said first class have a mean
coating level which is of from more than 0% to 100% of the
mean coating level of the composition, preferably 0% to
50%.
A second class comprises particles of from less than 850
micrometers to 500 micrometers. Particles of said second
class have a mean coating level of from 0% to 150% of the
mean coating level of the composition, preferably from o%
to 100%.
A third class comprises particles of from less than 500
micrometers to 250 micrometers. Particles of said third
class .have a mean coating level of from 50% to 300 % of
the mean coating level of the composition, preferably from
75% to 275%, most preferably 100% to 250%
A process for manufacturing a preferred solid peroxyacid
bleach precursor according to the present invention
includes the steps of .
WO 94/15010 PCT/US93/06818
2~.4~5~
- co-agglomerating a peroxyacid bleach precursor with a
binder material as hereinbefore defined;
- optionally drying said co-agglomerate;
- coating said dried co-agglomerate with a coating
material as hereinbefore defined;
- drying said coated co-agglomerate.
According to said process the peroxyacid bleach precursor
powder must be co-agglomerated into a water-soluble acidic
polymer binder material as hereinabefore defined. Any
agglomerating technique known to the man skilled in the
art is suitable for use herein.
The co-agglomerated particulate material does not itself
provide the benefits of the invention, and said co-
agglomerated material needs to be coated with a water-
soluble acidic polymer as hereinabove defined. The
coating of the co-agglomerated material with the coating
material can be carried out in several ways.
The coating material may be sprayed on as a molten
material or as a solution or dispersion in a
solvent/carrier liquid which is subsequently removed by
evaporation. The coating material can also be applied as a
powder coating e.g. by electrostatic techniques although
this is less preferred as the adherence of powdered
coating material is more difficult to achieve and can be
more expensive.
WO 94/15010 Z~~S8~ PCTIUS93/06818
16
Molten coating is a preferred technique for coating
materials of Mpt<80°C but is less convenient for higher
Melting Point acids (i.e. >100°C). For coating materials
of Mpt>80°C, spray on as a solution or dispersion is
preferred. Organic solvents such as ethyl and isopropyl
alcohol can be used to form the solutions or dispersions,
although this will necessitate a solvent recovery stage in
order to make their use economic. However, the use of
organic solvents also gives rise to safety problems such as
flammability and operator safety and thus aqueous solutions
or dispersions are preferred.
Aqueous solutions are particularly advantageous as the
coating materials herein have a high aqueous solubility,
provided the solution has a sufficiently low viscosity to
enable it to be handled. Preferably a concentration of at
least 25% by weight of the coating material in the solvent
is used in order to reduce the drying/evaporation load
after surface treatment has taken place. The treatment
apparatus can be any of those normally used for this
purpose, such as inclined rotary pans, rotary drums and
fluidised beds, high and low speed mixers (Lodige).
In the present invention, it is essential to control the
coating distribution to ensure that the smaller particles
are more coated than the larger particles.
An appropriate way to control the coating level as a
function of the particle size in the process to be used for
the manufacturing of the particles of the present
invention, is to separate the particles of the composition
into several streams of particles of different sizes after
the agglomeration step, and coat-treat each stream
individually.
A more elegant way to control the coating level on the
particles is to use a fluid bed where the particles are
WO 94/15010 2141584 PCT/US93/06818
17
fluidized in an air stream. This fluidising provides a
natural particle size gradient with smaller particles at
the top of the bed and larger particles at the bottom. The
coating material is then sprayed onto the particles, and an
appropriate coating can be achieved by appropriately
positioning the spray jet or jets. Specifically, increased
spraying at the top of the bed will provide a higher
coating level on the small particles.
Solid peroxyacid bleach precursor compositions in
accordance with the invention can be used in a variety of
applications. Thus the peroxyacid bleach compositions may
themselves be incorporated into other solid compositions
such as tablets, extrudate$ and agglomerates. The
compositions can also be suspended in nonaqueous liquid
compositions in which the organic acid surface treating
material is insoluble and inert. However, the preferred
application for the solid peroxybleach precursor
compositions of the invention is as particulate components
of granular detergent compositions, particularly the so-
called concentrated detergent compositions that are added
to a washing machine by means of a dosing device placed in
the machine drum with the soiled fabric load. Concentrated
granular detergent compositions dispensed into the wash
liquor via a dosing device are more subject to dissolution
problems, than compositions added via the dispensing
compartment of a washing machine because, in the initial
stages of a wash cycle, the agitation in the immediate
environment of the product is inhibited by the presence of
the fabric load. Whilst this can constitute a benefit in
permitting the development of high transient concentrations
of builder and surfactant, the development of high
transient peroxyacid concentrations can, as noted
previously, lead to fabric and colour damage. The
compositions of the present invention, when incorporated
into concentrated detergent products delivered to the wash
liquor via a dispensing device, mitigate if not eliminate
this problem.
wo 9ansolo 2~-~~''''~~
PCT/US93/06818
18
Detergent compositions incorporating the coated peroxy acid
bleach precursor composition of the present invention will
normally contain from 0.5% to 20% of the precursor
composition, more frequently from 1% to 9% and most
preferably from 3% to 8%, on a composition weight basis.
Such detergent compositions will, of course, contain a
source of alkaline hydrogen peroxide necessary to form a
peroxyacid bleaching species in the wash solution and
preferably will also contain other components conventional
in detergent compositions. Thus preferred detergent
compositions will incorporate one of more of surfactants,
organic and inorganic builders, soil suspending and anti-
redeposition agents, suds suppressors, enzymes, fluorescent
whitening agents, photo activated bleaches, perfumes and
colours.
Detergent compositions incorporating the coated particulate
peroxyacid precursors of the present invention will include
an inorganic perhydrate bleach, normally in the form of the
sodium salt, as the source of alkaline hydrogen peroxide in
the wash liquor. This perhydrate is normally incorporated
at a level of from 3% to 35% by weight, more preferably
from 3% to 35% by weight and most preferably from 5% to 30%
by weight of the composition.
The perhydrate may be any of the inorganic salts such as
perborate, percarbonate, perphosphate and persilicate salts
but is conventionally an alkali metal perborate or
percarbonate. Whilst fabric colour damage arising from
compositions in accordance with the invention is low,
irrespective of whether a perborate or percarbonate salt is
employed, the improvement in comparison with uncoated
precursor particulates is more noticeable with percarbonate
bleach as this causes greater fabric colour damage in the
absence of any coating on the bleach precursor.
WO 94/15010 '?'~4~-~ .~' ~ PCT/US93/06818
19
Sodium percarbonate, which is the preferred perhydrate, is
an addition compound having a formula corresponding to
2Na2C03.3H202, and is available commercially as a
crystalline solid. Most commercially available material
includes a low level of a heavy metal sequestrant such as
EDTA, 1-hydroxyethylidene 1, 1-diphosphonic acid (HEDP) or
an amino-phosphonate, that is incorporated during the
manufacturing process. For the purposes of the detergent
composition aspect of the present invention, the
percarbonate can be incorporated into detergent
compositions without additional protection, but preferred
executions of such compositions utilise a coated form of
the material. A suitable coating is sodium silicate of
Si02:Na20 ratio from 1.6:1 to~ 3.4:1, preferably 2.8:1,
applied as an aqueous solution to give a level of from 2%
to 10%, (normally from 3% to 5%) of silicate solids by
weight of the percarbonate. Another coating is a mixed
salt of an alkali metal sulphate and carbonate. Such
coatings together with coating processes have previously
been described in GH-1,466,799, granted to Interox on 9th
March 1977. The weight ratio of the mixed salt coating
material to percarbonate lies in the range from 1:200 to
1:4, more preferably from 1:99 to 1:9, and most preferably
from 1:49 to 1:19. Preferably, the mixed salt is of sodium
sulphate and sodium carbonate which has the general formula
Na2S04.n.Na2C03 wherein n is from 0.1 to 3, preferably n is
from 0.3 to 1.0 and most preferably n is from 0.2 to 0.5.
Magnesium silicate can also be included in the coating.
The particle size range of the crystalline percarbonate is
from 350 micrometers to 450 micrometers with a mean of
approximately 400 micrometers. When coated, 60 % to 80% by
weight of the crystals have a size greater than 425
micrometers, with a mean of approximately 650 micrometers
Whilst heavy metals present in the sodium carbonate used to
manufacture the percarbonate can be controlled by the
inclusion of sequestrants in the reaction mixture, the
. 21 41 584
zo
percarbonate still requires protection from heavy metals
present as impurities in other ingredients of the product.
Accordingly, in detergent compositions utilising
percarbonate as the perhydrate salt, the total level of
Iron, Copper and Manganese ions in the product should not
exceed 25 ppm and preferably should be less than 20 ppm in
order to avoid an unacceptably adverse effect on
percarbonate stability. Detergent compositions in which
alkali metal percarbonate bleach has enhanced stability are
disclosed in the Applicants copending Canadian Patent
Application No. 2,093,438.
A wide range of surfactants can be used in the detergent
compositions. A typical listing of anionic, nonionic,
ampholytic and zwitterionic classes, and species of these
surfactants, is given in U.S.P. 3,929,678 issued to
Laughlin and Heuring on December, 30, 1975. A list of
suitable cationic surfactants is given in U.S.P. 4,259,217
issued to Murphy on March 31, 1981.
Mixtures of anionic surfactants are suitable herein,
particularly blends of sulphate, sulphonate and/or
carboxylate surfactants. Mixtures of sulphonate and
sulphate surfactants are normally employed in a sulphonate
to sulphate weight ratio of from 5:1 to 1:2, preferably
from 3:1 to 2:3, more preferably from 3:1 to 1:1.
Preferred sulphonates include alkyl benzene sulphonates
having from 9 to 15, especially 11 to 13 carbon atoms in
the alkyl radical, and alpha-sulphonated methyl fatty acid
esters in which the fatty acid is derived from a C12-C18
fatty source, preferably from a C16-Clg fatty source. In
each instance the cation is an alkali metal, preferably
sodium. Preferred sulphate surfactants in such sulphonate
sulphate mixtures are alkyl sulphates having from 12 to 22,
preferably 16 to 18 carbon atoms in the alkyl radical.
Another useful surfactant system comprises a mixture of two
alkyl sulpl-.ate materials whose respective mean chain
lengths differ from each other. One such system comprises
B
WO 94/15010 PCT/US93/06818
2~.~~:584
21
a mixture of C14-C15 alkyl sulphate and C16-Clg alkyl
sulphate in a weight ratio of C14-C15~ C16-C18 of from 3:1
to 1:1. The alkyl sulphates may also be combined with
alkyl ethoxy sulphates having from 10 to 20, preferably 10
to 16 carbon atoms in the alkyl radical and an average
degree of ethoxylation of 1 to 6. The cation in each
instance is again an alkali metal, preferably sodium.
Other anionic surfactants suitable for the purposes of the
invention are the alkali metal sarcosinates of formula
R-CON (R) CH2 COOM wherein R is a Cg-C17 linear or branched
alkyl or alkenyl group, R' is a C1-C4 alkyl group and M is
an alkali metal ion. Preferred examples are the lauroyl,
Cocoyl (C12-C14), myristyl and oleyl methyl sarcosinates in
the form of their sodium salts.,
One class of nonionic surfactants useful in the present
invention comprises condensates of ethylene oxide with a
hydrophobic moiety, providing surfactants having an average
hydrophilic-lipophilic balance (HLB) in the range from 8 to
17, preferably from 9.5 to 13.5, more preferably from 10 to
12.5. The hydrophobic (lipophilic) moiety may be aliphatic
or aromatic in nature and the length of the polyoxyethylene
group which is condensed with any particular hydrophobic
group can be readily adjusted to. yield a water-soluble
compound having the desired degree of balance between
hydrophilic and hydrophobic elements.
Especially preferred nonionic surfactants of this type are
the Cg-C15 primary alcohol ethoxylates containing 3-8 moles
of ethylene oxide per mole of alcohol, particularly the
C14-C15 primary alcohols containing 6-8 moles of ethylene
oxide per mole of alcohol and the C12-C14 primary alcohols
containing 3-5 moles of ethylene oxide per mole of alcohol.
Another class of nonionic surfactants comprises alkyl
polyglucoside compounds of general formula
RO (CnH2n0)tZx
WO 94/15010 PCTIUS93l06818
1214~.~~4
22
wherein Z is a moiety- derived from glucose; R is a
saturated hydrophobic alkyl group that contains from 12 to
18 carbon atoms; t is from 0 to 10 and n is 2 or 3; x is
from 1.3 to 4, the compounds including less than l00
unreacted fatty alcohol and less than 50% short chain alkyl
polyglucosides. Compounds of this type and their use in
detergent compositions are disclosed in EP-B 0070074,
0070077, 0075996 and 0094118.
A further class of surfactants are the semi-polar
surfactants such as amine oxides. Suitable amine oxides
are selected from mono C8-C20, preferably C10-C14 N-alkyl
or alkenyl amine oxides and propylene-1,3-diamine dioxides
wherein the remaining N positions are substituted by
methyl, hydroxyethyl or hydroxpropyl groups.
Cationic surfactants can also be used in the detergent
compositions herein and suitable quaternary ammonium
surfactants are selected from mono Cg-C16, preferably C10-
C14 N-alkyl or alkenyl ammonium surfactants wherein
remaining N positions are substituted by methyl,
hydroxyethyl or hydroxypropyl groups.
The detergent compositions comprise from 5o to 20% of
surfactant but more usually comprise from 7% to 20%, more
preferably from 10% to 15% surfactant by weight of the
compositions.
Combinations of surfactant types are preferred, more
especially anionic-nonionic and also anionic-nonionic-
cationic blends. Particularly preferred combinations are
described in GB-A-2040987 and EP-A-0087914. Although the
surfactants can be incorporated into the compositions as
mixtures, it is preferable to control the point of addition
of each surfactant in order to optimise the physical
characteristics of the composition and avoid processing
problems. Preferred modes and orders of surfactant
addition are described hereinafter.
r _~~~_._...__.._. .. _.....T_ ._ _..__,..__._ ~_T.r.~~_.__... ._ _ .. _
_._~."._..~.~..~..
WO 94J15010 PCT/US93J06818
23
Another highly preferred component of detergent
compositions incorporating the coated peroxy acid precursor
particulates of the invention is a detergent builder system
comprising one or more non-phosphate detergent builders.
These can include, but are not restricted to alkali metal
carbonates, bicarbonates, silicates, aluminosilicates,
monomeric polycarboxylates, homo or copolymeric
polycarboxylic acids or their salts in which the
polycarboxylic acid comprises at least two carboxylic
radicals separated from each other by not more than two
carbon atoms, organic phosphonates and aminoalkylene poly
(alkylene phosphonates) and mixtures of any of the
foregoing. The builder system,is present in an amount of
from 25% to 60% by weight of the composition, more
preferably from 30% to 60% by weight.
Preferred builder systems are free of boron compounds and
any polymeric organic materials are preferably
biodegradable.
Suitable silicates are those having an Si02:Na20 ratio in
the range from 1.6 to 3.4, the so-called amorphous
silicates of Si02 . Na20 ratios from 2.0 to 2.8 being
preferred. These materials can be added at various points
of the manufacturing process, such as in a slurry of
components that are spray dried or in the form of an
aqueous solution serving as an agglomerating agent for
other solid components, or, where the silicates are
themselves in particulate form, as solids to the other
particulate components of the compositor. However, for
compositions in which the percentage of spray dried
components is low i.e. 30%, it is preferred to include the
amorphous silicate in the spray-dried components.
Within the silicate class, highly preferred materials are
crystalline layered sodium silicates of general formula
WO 94/15010 21'~~"58~ PCT/US93/06818
24
NaMSix02x+l.yH2~
wherein M is sodium or hydrogen, x is a number from 1.9 to
4 and y is a number from 0 to 20. Crystalline layered
sodium silicates of this type are disclosed in EP-A-0164514
and methods for their preparation are disclosed in DE-A-
3417649 and DE-A-3742043. For the purposes of the present
invention, x in the general formule above has a value of 2,
3 or 4 and is preferably 2. More preferably M is sodium
and y is 0 and preferred examples of this formula comprise
the q'~ ~ ~ Y and ~j forms of Na2Si205 . These materials are
available from Hoechst AG FRG as respectively NaSKS-11 and
NaSKS-6. The most preferred material is ~ -Na2Si205,
(NaSKS-6). Crystalline layered silicates are incorporated
either as dry mixed solids, or as solid components of
agglomerates with other components.
Whilst a range of aluminosilicate ion exchange materials
can be used, preferred sodium aluminosilicate zeolites have
the unit cell formula
Naz [(A102 ) z (Si02 )y ] xH 20
wherein z and y are at least 6; the molar ratio of z to y
is from 1.0 to 0.5 and x is at least 5, preferably from 7.5
to 276, more preferably from 10 to 264. The
aluminosilicate materials are in hydrated form and are
preferably crystalline, containing from l0% to 280, more
preferably from 18% to 22% water in bound form.
The above aluminosilicate ion exchange materials are
further characterised by a particle size diameter of from
0.1 to 10 micrometers, preferably from 0.2 to 4
micrometers. The term "particle size diameter" herein
represents the average particle size diameter of a given
ion exchange material as determined by conventional
analytical techniques such as, for example, microscopic
determination utilizing a scanning electron microscope or
T _._~. ___._ ~ ._..
WO 94115010 ,"~~,~~~8~ PCTIUS93I06818
by means of a laser granulometer. The aluminosilicate ion
exchange materials are further characterised by their
calcium ion exchange capacity, which is at least 200 mg
equivalent of CaCO3 water hardness/g of aluminosilicate,
calculated on an anhydrous basis, and which generally is in
the range of from 300 mg eq./g to 352 mg eq./g. The
aluminosilicate ion exchange materials herein are still
further characterised by their calcium ion exchange rate
which is at least 130 mg equivalent of
CAC03/litre/minute/(g/litre) [2 grains Ca++/
gallon/minute/gram/gallon)] of aluminosilicate (anhydrous
basis), and which generally lies within the range of from
130 mg equivalent of CaCO3/litre/minute/(gram/litre) [2
grains/gallon/minute/ (gram/gallon).] to 39o mg equivalent
of CaC03/litre/minute/ (gram/litre) [6
grains/gallon/minute/(gram/gallon)], based on calcium ion
hardness.
Optimum aluminosilicates for builder purposes exhibit a
calcium ion exchange rate of at least 260 mg equivalent of
CaCO3/litre/ minute/ (gram/litre) (4
grains/gallon/minute/(gram/gallon)].
Aluminosilicate ion exchange materials useful in the
practice of this invention are commercially available and
can be naturally occurring materials, but are preferably
synthetically derived. A method for producing
aluminosilicate ion exchange materials is discussed in US
Patent No. 3,985,669. Preferred synthetic crystalline
aluminosilicate ion exchange materials useful herein are
available under the designations Zeolite A, Zeolite B,
Zeolite X, Zeolite HS and mixtures thereof. In an
especially preferred embodiment, the crystalline
aluminosilicate ion exchange material is Zeolite A and has
the formula
Na 12 [(A102 ) 12 (Si02)12 ]. xH2 O
.. 21 41 584
26
wherein x is from 20 to 30, especially 27. Zeolite X of
formula Nag6 [(A102)g6(Si02)106J~ 276 H20 is also suitable,
as well as Zeolite HS of formula Na6 [(A102)6(Si02)6J 7.5
H2 O) .
Suitable water-soluble monomeric or oligomeric carboxylate
builders include lr.ctic acid, glycolic acid and ether
derivatives thereof as disclosed in Belgian Patent Nos.
831,368, 821,369 and 821,370. Polycarboxylates containing
two carboxy groups include the water-soluble salts of
succinic acid, malonic acid, (ethylenedioxy) diacetic acid,
malefic acid, diglycolic acid, tartaric acid, tartronic acid
and fumaric acid, as well as the ether carboxylates
described in German Offenlegenschrift 2,446,686, and
2,446,687 and U.S. Patent No. 3,935,257 and the sulfinyl
carboxylates described in Belgian Patent No. 840,623.
Polycarboxylates containing three carboxy groups include,
in particular, water-soluble citrates, aconitrates and
citraconates as well as succinate derivatives such as the
carboxymethyloxysuccinates described in British Patent No.
1,379,241, lactoxysuccinates described in British Patent
No. 1,389,732, and aminosuccinates described in Canadian
Patent No. 973,771, and the oxypolycarboxylate materials
such as 2-oxa-1,1,3-propane tricarboxylates described in
British Patent No. 1,387,447.
Polycarboxylates containing four carboxy groups incldue
oxydisuccinates disclosed in British Patent No. 1,261,829,
1,1,2,2-ethane tetracarboxylates, 1,1,3,3-propane
tetracarboxylates and 1,1,2,3-propane tetracarboxylates.
Polycarboxylates containing sulfo substituents include the
sulfosuccinate derivatives disclosed in British Patent Nos.
1,398,421 and 1,398,422 and in U.S. Patent No. 3,936,448,
and the sulfonated pyrolysed citrates described in British
Patent No. 1,439,000.
Alicyclic and heterocyclic polycarboxylates include
cyclopentane-cis,cis,cis-tetracarboxylates,
B
--- WO 94/15010 2~4~s~,~ PCTIUS93I06818
27
cyclopentadienide pentacarboxylates, 2,3,4,5-
tetrahydrofuran - cis, cis, cis-tetracarboxylates, 2,5-
tetrahydrofuran - cis - dicarboxylates, 2,2,5,5-
tetrahydrofuran - tetracarboxylates, 1,2,3,4,5,6-hexane -
hexacarboxylates and carboxymethyl derivatives of
polyhydric alcohols such as sorbitol, mannitol and xylitol.
Aromatic polycarboxylates include mellitic acid,
pyromellitic acid and the phthalic acid derivatives
disclosed in British Patent No. 1,425,343.
Of the above, the preferred polycarboxylates are
hydroxycarboxylates containing up to three carboxy groups
per molecule, more particularly citrates.
The parent acids of the , monomeric or oligomeric
polycarboxylate chelating agents or mixtures thereof with
their salts, e.g. citric acid or citrate/citric acid
mixtures are also contemplated as components of builder
systems of detergent compositions in accordance with the
present invention.
Other suitable water soluble organic salts are the homo- or
co-polymeric polycarboxylic acids or their salts in which
the polycarboxylic acid comprises at least two carboxyl
radicals separated from each other by not more than two
carbon atoms. Polymers of the latter type are disclosed in
GB-A-1,596,756. Examples of such salts are polyacrylates
of MWt 2000-5000 and their copolymers with malefic
anhydride, such copolymers having a molecular weight of
from 20,000 to 70,000, especially about 40,000. Such
builder polymeric materials may be identical to the
polymeric materials as binder materials and coating
materials, as described hereinabove. These materials are
normally used at levels of from 0.5% to 10°s by weight more
preferably from 0.750 to 8%, most preferably from to to 60
by weight of the composition.
Another preferred polycarboxylate builder is ethylenediamine-
N,N'-disuccinic acid (EDDS) or the alkali metal, alkaline earth
~14~..~84
WO 94/15010 PCT/US93/06818
28
metal, ammonium, or substituted ammonium salts thereof, or
mixtures thereof. Preferred EDDS compounds are the free acid
form and the sodium or magnesium salt thereof. Examples of such
preferred sodium salts of EDDS include NaEDDS, Na2EDDS and
Na4EDDS. Examples of such preferred magnesium salts of EDDS
include Mg EDDS and Mg2EDDS. The magnesium salts are the most
preferred for inclusion in compositions in accordance with the
invention.
The structure of the acid form of EDDS is as follows .
H-N-CH2-CH2-N-H
CH2 H CH CH2
I i I I
COON COON , COOH COON
EDDS can be synthesised, for example, from readily available,
inexpensive starting material such as malefic anhydride and
ethylene diamine as follows .
O
2 O=C C=O + NH2-CH2-CH2-NH2+Na~ EODS
d
CH CH
A more complete disclosure of methods for synthesising EDDS from
commercially available starting materials can be found in US
Patent 3,158,635, Kezerian and Ramsay, issued November 24, 1964.
The synthesis of EDDS from malefic anhydride and ethylene diamine
yields a mixture of three optical isomers, [R,R],[S,S], and
[S,R], due to the two asymmetric carbon atoms. The
biodegradation of EDDS is optical isomerspecific, with the (S, S]
isomer degrading most rapidly and extensively, and for this
reason the [S,S] isomer is most preferred for inclusion in the
compositions of the invention.
r t _ _ .. . r .. _ ._.. _._... _._.~ T .~... . .t ...._. _
--- WO 94!15010 214184 PCT/US93/06818
29
The [S, S] isomer of EDDS can be synthesised from L-aspartic acid
and 1,.2-dibromoethane, as follows .
2 CH2--CH-NH2 + Br-CH2-CH2-BR N Q [S,S]~DDS
COON COOH
A more complete disclosure of the reaction of L-aspartic acid
with 1,2-dibromoethane to form the [S,S] isomer of ~DOS can be
found in Neal and Rose, Stereospecific Ligands and Their
Complexes of Ehtylenediaminediscuccinic Acid, Inorcxanic
Chemistry, Vol 7 (1968), pp. 2405-2412.
Organic phosphonates and amino alkylene poly (alkylene
phosphonates) include alkali, metal ethane 1-hydroxy
diphosphonates, nitrilo trimethylene phosphonates, ethylene
diamine tetra methylene phosphonates and diethylene
triamine penta methylene phosphonates, although these
materials are less preferred where the minimisation of
phosphorus compounds in the compositions is desired.
For the purposes of detergent compositions embodying the
surface treated bleach precursor particulates of the
invention , the non-phosphate builder ingredient will
comprise from 25% to 60% by weight of the compositions,
more preferably from 30% to 60% .by weight. Within the
preferred compositions, sodium aluminosilicate such as
Zeolite A will comprise from 20% to 60% by weight of the
total amount of builder, a monomeric or oligomeric
carboxylate will comprise from l0% to 30% by weight of the
total amount of builder and a crystalline layered silicate
will comprise from 10% to 65% by weight of the total amount
of builder. In such compositions the builder ingredient
preferably also incorporates a combination of auxiliary
inorganic and organic builders such as sodium carbonate and
malefic anhydride/acrylic acid copolymers in amounts of up
to 35% by weight of the total builder.
WO 94/15010 y ~1'41'~8~ pCT/US93/06818
.30
Anti-redeposition and soil-suspension agents suitable
herein include cellulose derivatives such as
methylcellulose, carboxymethylcellulose and
hydroxyethycellulose, and homo-or co-polymeric
polycarboxylic acids or their salts. Polymers of this type
include copolymers of malefic anhydride with ethylene,
methylvinyl ether or methacrylic acid, the malefic anhydride
constituting at least 20 mole percent of the copolymer.
These materials are normally used at levels of from 0.5% to
10% by weight, more preferably from 0.75% to 8%, most
preferably from 1% to 6% by weight of the composition.
Other useful polymeric materials are the polyethylene
glycols, particularly those of, molecular weight 1000-10000,
more particularly 2000 to 8000 and most preferably about
4000. These are used at levels of from 0.20% to 5% more
preferably from 0.25% to 2.5% by weight. These polymers
and the previously mEntioned homo- or co-polymeric
polycarboxylate salts are valuable for improving whiteness
maintenance, fabric ash deposition, and cleaning
performance on clay, proteinaceous and oxidizable soils in
the presence of transition metal impurities.
Preferred optical brighteners are anionic in character,
examples of which are disodium 4,41-bis-(2-diethanolamino-
4-anilino -s- triazin-6- ylamino)stilbene-2:21
disulphonate, disodium 4,41-bis-(2-morpholino -4-anilino-2-
triazin-6-ylaminostilbene-2:21-disulphonate,disodium 4, 41-
bis-(2,4-dianilino-s-triazin-6-ylamino)stilbene-2:21 -
disulphonate, monosodium 41.411-bis-(2,4-dianilino-s-
triazin-6 ylamino)stilbene-2- sulphonate, disodium 4,41-
bis-(2-anilino-4-(N-methyl-N-2-hydroxyethylamino)-2-
triazin-6-
ylamino)stilbene-2,21 - disulphonate, disodium 4,41-bis-(4-
phenyl-2,1,3-triazol-2-yl)stilbene-2,21 disulphonate,
disodium 4,41bis(2-anilino-4-(1-methyl-2-
hydroxyethylamino)-s-triazin-6-ylamino)stilbene-
T ~ ....~~.~.__........_ ~ _._..__... . ...._
PCT/US93/06818
_. WO 94/15010
31
2,21disulphonate and sodium 2(stilbyl-411-(naphtho-
11,21:4,5)-1,2,3 - triazole-211- sulphonate.
Soil-release agents useful in compositions of the present
invention are conventionally copolymers or terpolymers of
terephthalic acid with ethylene glycol and/or propylene
glycol units in various arrangements. Examples of such
polymers are disclosed in the commonly assigned US Patent
Nos. 4116885 and 4711730 and European Published Patent
Application No. 0272033. A particular preferred polymer in
accordance with EP-A-0272033 has the formula
(CH3(PEG)43)0.75(POH)0.25~ PO)2.8~-PEG)0.4)T(PO-
H)0.25((PEG)43CH3)0.75
where PEG is -(OC2H4)O-, PO is (OC3Hg0) and T is (pCOCgH4C0).
Certain polymeric materials such as polyvinyl pyrrolidones
typically of MWt 5000-20000, preferably 10000-15000, also
form useful agents in preventing the transfer of labile
dyestuffs between fabrics during the washing process.
Another optional detergent composition ingredient is a suds
suppressor, exemplified by silicones, and silica-silicone
mixtures. Silicones can be generally represented by
alkylated polysiloxane materials while silica is normally
used in finely divided forms, exemplified by silica
aerogels and xerogels and hydrophobic silicas of various
types. These materials can be incorporated as particulates
in which the suds suppressor is advantageously releasably
incorporated in a water-soluble or water-dispersible,
substantially non-surface-active detergent-impermeable
carrier. Alternatively the suds suppressor can be
dissolved or dispersed in a liquid carrier and applied by
spraying on to one or more of the other components.
As mentioned above, useful silicone suds controlling agents
can comprise a mixture of an alkylated siioxane, of the
WO 94/15010 PCT/US93/06818
32
type referred to hereinbefore, and solid silica. Such
mixtures are prepared by affixing the silicone to the
surface of the solid silica. A preferred silicone suds
controlling agent is represented by a hydrophobic silanated
(most preferably trimethyl-silanated) silica having a
particle size in the range from 10 nanometers to 20
nanometers and a specific surface area above 50 m2/g,
intimately admixed with dimethyl silicone fluid having a
molecular weight in the range from about 500 to about
200,000 at a weight ratio of silicone to silanated silica
of from about 1:1 to about 1:2.
A preferred silicone suds controlling agent is disclosed in
Bartollota et al. US Patent 3,933,672. Other particularly
useful suds suppressors are the self-emulsifying silicone
suds suppressors, described in German Patent Application
DTOS 2,646,126 published April 28, 1977. An example of
such a compound is DC0544, commercially available from Dow
Corning, which is a siloxane/glycol copolymer.
The suds suppressors described above are normally employed
at levels of from 0.001% to 0.5% by weight of the
composition, preferably from 0.01% to 0.1% by weight.
The preferred methods of incorporation comprise either
application of the suds suppressors in liquid form by
spray-on to one or more of the major components of the
composition or alternatively the formation of the suds
suppressors into separate particulates that can then be
mixed with the other solid components of the composition.
The incorporation of the suds modifiers as separate
particulates also permits the inclusion therein of other
suds controlling materials such as C20-C24 fatty acids,
microcrystalline waxes and high MWt copolymers of ethylene
oxide and propylene oxide which would otherwise adversely
affect the dispersibility of the matrix. Techniques for
forming such suds modifying particulates are disclosed in
......_... ...~..T.... ........ ., _ ...... __.
WO 94/15010 ~1,4.~5,84 PCTIUS93/06818
33
the previously mentioned Bartolotta et al US Patent No.
3,933,672.
Another optional ingredient useful in the present invention
is one or more enzymes.
Preferred enzymatic materials include the commercially
available amylases, neutral and alkaline proteases,
lipases, esterases and cellulases conventionally
incorporated into detergent compositions. Suitable enzymes
are discussed in US Patents 3,519,570 and 3,533,139.
Fabric softening agents can also be incorporated into
detergent compositions in acGOrdance with the present
invention. These agents may be inorganic or organic in
type. Inorganic softening agents are examplified by the
smectite clays disclosed in GB-A-1,400,898. Organic fabric
softening agents include the water insoluble tertiary
amines as disclosed in GB-A-1514276 and EP-B-0011340.
Their combination with mono C12-C14 Quaternary ammonium
salts is disclosed in EP-B-0026527 & 528. Other useful
organic fabric softening agents are the dilong chain amides
as disclosed in EP-B-0242919. Additional organic
ingredients of fabric softening systems include high
molecular weight polyethylene oxide materials as disclosed
in EP-A-0299575 and 0313146.
Levels of smectite clay are normally in the range from 5%
to 15%, more preferably from 8% to 12% by weight, with the
material being added as a dry mixed component to the
remainder of the formulation. Organic fabric softening
agents such as the water-insoluble tertiary amines or
dilong chain amide materials are incorporated at levels of
from 0.5% to 5% by weight, normally from 1% to 3% by
weight, whilst the high molecular weight polyethylene oxide
materials and the water soluble cationic materials are
added at levels of from 0.1% to 2%, normally from 0.15% to
~141~~
WO 94!15010 PCT/US93/06818
34
1.5% by weight. Where a portion of the composition is
spray dried, these materials can be added to the aqueous
slurry fed to the spray drying tower, although in some
instances it may be more convenient to add them as a dry
mixed particulate, or spray them as a molten liquid on to
other solid components of the composition.
The coated peroxyacid bleach precursor particulates of the
present invention are particularly useful in concentrated
granular detergent compositions that are characterised by
a relatively high density in comparison with conventional
laundry detergent compositions. Such high density
compositions have a bulk density of at least 650 g/litre,
more usually at least 700 g/litre and more preferably in
excess of 800 g/litre.
Bulk density is measured by means of a simple funnel and
cup device consisting of a conical funnel moulded rigidly
on a base and provided with a flap valve at its lower
extremity to allow the contents of the funnel to be emptied
into an axially aligned cylindrical cup disposed below the
funnel. The funnel is 130 mm and 40 mm at its respective
upper and lower extremities. It is mounted so that the
lower extremity is 140 mm above the upper surface of the
base. The cup has an overall height of 90 mm, an internal
height of 87 mm and an internal diameter of 84 mm. Its
nominal volume is 500 ml.
To carry out a measurement, the funnel is filled with
powder by hand pouring, the flap valve is opened and powder
allowed to overfill the cup. The filled cup is removed
from the frame and excess powder removed from the cup by
passing a straight edged implement e.g. a knife, across its
upper edge. The filled cup is then weighed and the value
obtained for the weight of powder doubled to provide the
bulk density in g/litre. Replicate measurements are made as
required.
7.. _ r _.__ ..T____..__..~ _.
PCTIUS93/06818
WO 94/15010
Concentrated detergent compositions also normally
incorporate at least one multi-ingredient component i.e.
they do not comprise compositions formed merely by dry-
mixing individual ingredients. Compositions in which each
individual ingredient is dry-mixed are generally dusty,
slow to dissolve and also tend to cake and develop poor
particle flow characteristics in storage.
Subject to the above bulk density and component content
limitations, the compositions of the invention can be made
via a variety of methods including dry mixing, spray
drying, agglomeration and granulation and preferred methods
involve combinations of these techniques. A preferred
method of making the compositions involves a combination of
spray drying, agglomeration in a high speed mixer and dry
mixing.
Preferred detergent compositions in accordance with the
invention comprise at least two particulate multi-
ingredient components. The first component comprises at
least 15%, conventionally from 25% to 50%, but more
preferably no more than 35% by weight of the composition
and the second component from 1% to 50%, more preferably
lo% to 40% by weight of the composition.
The first component comprises a particulate incorporating
an anionic surfactant in an amount of from 0.75% to 40% by
weight of the powder and one or more inorganic and/or
organic salts in an amount of from 99.25% to 60% by weight
of the powder. The particulate can have any suitable form
such as granules, flakes, prills, marumes or noodles but is
preferably granular. The granules themselves may be
agglomerates formed by pan or drum agglomeration or by in-
line mixers but are customarily spray dried particles
produced by a atomising an aqueous slurry of the
ingredients in a hot air stream which removes most of the
water. The spray dried granules are then subjected to
densification steps, e.g. by high speed cutter mixers
WO 94115010 ~1.~"~-~~~ PCT/US93106818
'3~
and/or compacting mills, to increase density before being
reagglomerated. For illustrative purposes, the first
component is described hereinafter as a spray dried powder.
Suitable anionic surfactants for the purposes of the first
component have been found to be slowly dissolving linear
alkyl sulfate salts in which the alkyl group has an average
of from 16 to 22 carbon atoms, and linear alkyl carboxylate
salts in which the alkyl group has an average of from 16 to
24 carbon atoms. The alkyl groups for both types of
surfactant are preferably derived from natural sources such
as tallow fat and marine oils.
The level of anionic surfactant in the spray dried powder
forming the first component is from 0.75% to 40% by weight,
more usually 2.5% to 25% preferably from 3% to 20% and most
preferably from 5% to 15% by weight. Water-soluble
surfactants such as linear alkyl benzene sulphonates or
C14-C15 alkyl sulphates can be included or alternatively
may be applied subsequently to the spray dried powder by
spray on.
The other major ingredient of the spray dried powder is one
or more inorganic or organic salts that provide the
crystalline structure for the granules. The inorganic
and/or organic salts may be water-soluble or water-
insoluble, the latter type being comprised by the, or the
major part of the, water-insoluble builders where these
form part of the builder ingredient. Suitable water
soluble inorganic salts include the alkali metal carbonates
and bicarbonates. Alkali metal silicates other than
crystalline layered silicates can also be present in the
spray dried granule provided that aluminosilicate does not
form part of the spray dried component.
However, in concentrated detergent compositions it is
preferred that water-soluble sulphate, particularly sodium
sulphate, should not be present at a level of more than
T r __.~ ~~._._T _ _ . T.
PCT/US93/06818
WO 94/15010
37
2.5o by weight of the composition. Preferably no sodium
sulphate is added as a separate ingredient and its
incorporation as a by-product e.g. with sulph(on)ated
surfactants, should be minimised.
Where an aluminosilicate zeolite forms the, or part of the,
builder ingredient, it is preferred that it is not added
directly by dry-mixing to the other components, but is
incorporated into the multi-ingredient component(s). Where
incorporation of the zeolite takes place in the spray-dried
granule, any silicate present should not form part of the
spray-dried granule. In these circumstances, incorporation
of the silicate can be achieved in several ways, e.g. by
producing a separate silicate-containing spray-dried
particulate, by incorporating the silicate into an
agglomerate of other ingredients, or more preferably by
adding the silicate as a dry mixed solid ingredient.
The first component can also include up to 15% by weight of
miscellaneous ingredients such as brighteners, anti-
redeposition agents, photoactivated bleaches (such as
tetrasulfonated zinc phthalocyanine) and heavy metal
sequestering agents. Where the first component is a spray
dried powder it will normally be dried to a moisture
content of from 7 % to 11 % by weight , more preferably from
8% to 10% by weight of the spray dried powder. Moisture
contents of powders produced by other processes such as
agglomeration may be lower and can be in the range 1-10% by
weight.
The particle size of the first component is conventional
and preferably not more than 5 o by weight should be above
l.4mm, while not more than 10% by weight should be less
than 0.15 mm in maximum dimension. Preferably at least
600, and most preferably at least 80%, by weight of the
powder lies between 0.7 mm and 0.25 mm in size. For spray
dried powders, the bulk density of the particles from the
spray drying tower is conventionally in the range from 540
WO 94115010 PCT/US93106818
21415~~
38 ~.
to 600 g/litre and this is then enhanced by further
processing steps such as size reduction in a high speed
cutter/mixer followed by compaction. Alternatively,
processes other than spray drying may be used to form a
high density particulate directly.
A second component o~ a preferred composition in accordance
with the invention is another multi-ingredient particulate
containing a water soluble surfactant.
This may be anionic, nonionic, cationic or semipolar in
type or a mixture of any of these. Suitable surfactants
are listed hereinbefore but preferred surfactants are C14-
C15 alkyl sulphates, linear ,C11- C15 alkyl benzene
sulphonates and fatty C14-Cig methyl ester sulphonates.
The second component may have any suitable physical form,
i.e. it may take the form of flakes, grills, marumes,
noodles, ribbons, or granules which may be spray-dried or
non spray-dried agglomerates. Although the second
component could in theory comprise the water soluble
surfactant on its own, in practice at least one organic or
inorganic salt is included to facilitate processing. This
provides a degree of crystallinity, and hence acceptable
flow characteristics, to the particulate and may be any one
or more of the organic or inorganic salts present in the
first component.
The particle size range of the second component should be
such as to obviate segregation from the particles of the
first component when blended therewith. Thus not more than
5% by weight should be above 1.4 mm while not more than 10%
should be less than 0.15 mm in maximum dimension.
The bulk density of the second component will be a function
of its mode of preparation. However, the preferred form of
the second component is a mechanically mixed agglomerate
which may be made by adding the ingredients dry or with an
1 ~ _._.._~_~...__T ~ _._.___._._p_ _. T
PCTIUS93/06818
WO 94/15010
39
agglomerating agent to a pan agglomerator, Z blade mixer or
more preferably an in-line mixer such as those manufactured
by Schugi (Holland) BV, 29 Chroomstraat 8211 AS, Lelystad,
Netherlands and Gebruder Lodige Maschinenbau GmbH, D-4790
Paderborn 1, Elsenerstrasse 7-9, Postfach 2050 F.R.G. By
this means the second component can be given a bulk density
in the range from 650 g/litre to 1190 g/litre more
preferably from 750 g/litre to 850 g/litre.
Preferred compositions include a level of alkali metal
carbonate in the second component corresponding to an
amount of from 3% to 15% by weight of the composition, more
preferably from 5% to 12% by weight. This will provide a
level of carbonate in the second component of from 20% to
40% by weight.
A highly preferred ingredient of the second component is
also a hydrated water insoluble aluminosilicate ion
exchange material of the synthetic zeolite type, described
hereinbefore, present at from 10% to 35% by weight of the
second component. The amount of water insoluble
aluminosilicate material incorporated in this way is from
1% to 10% by weight of the composition, more preferably
from 2% to 8% by weight.
In one process for preparing the second component, the
surfactant salt is formed in situ in an inline mixer. The
liquid acid form of the surfactant is added to a mixture of
particulate anhydrous sodium carbonate and hydrated sodium
aluminosilicate in a continuous high speed blender, such as
a Lodige KM mixer, and neutralised to form the surfactant
salt whilst maintaining the particulate nature of the
mixture. The resultant agglomerated mixture forms the
second component which is then added to other components of
the product. In a variant of this process, the surfactant
salt is pre-neutralised and added as a viscous paste to the
mixture of the other ingredients. In the variant, the
2141584
mixer serves merely to agglomerate the ingredients to form
the second component.
In a particularly preferred process for making detergent
compositions incorporating the coated peroxyacid bleach
precursor par~ticulates of the invention, part of the spray
dried product comprising the first granular component is
diverted and subjected to a loW level of nonionic
surfactant spray on before being reblended with the
remainder. The second granular component is made using the
preferred process described above. The first and second
components together with the coated bleach precursor
particulate and the perhydrate bleach, other dry mix
ingredients such as any carboxylate chelating agent, soil-
release polymer, silicate of conventional or crystalline
layered type, and enzyme are then fed to a conveyor belt,
from which they are transferred to a horizontally rotating
drum in which perfume and silicone suds suppressor are
sprayed on to the product. In highly preferred
compositions, a further drum mixing step is employed in
which a low (approx. 2% by weight) level of finely divided
crystalline material is introduced to increase density and
improve granular flow characteristics.
In preferred concentrated detergent products incorporating
an alkali metal percarbonate as the perhydrate salt it has
been found necessary to control several aspects of the
product such as its heavy metal ion content and its
equilibrium relative humidity. Sodium percarbonate-
containing compositions of this type having enhanced
stability are disclosed in the commonly assigned CA 2,093,438.
Compositions in accordance with the invention can also
benefit from delivery systems that provide transient
localised high concentrations of product in the drum of an
automatic washing machine at the start of the wash cycle,
B
WO 94/15010 ~~~~"~~4 PCT/US93/06818
S~ 1
thereby also avoiding problems associated with loss of
product in the pipework or sump of the machine.
Delivery to the drum can most easily be achieved by
incorporation of the composition in a bag or container from
which it is rapidly releasable at the start of the wash
cycle in response to agitation, a rise in temperature or
immersion in the wash water in the drum. Alternatively the
washing machine itself may be adapted to permit direct
addition of the composition to the drum e.g. by a
dispensing arrangement in the access door.
Products comprising a detergent composition enclosed in a
bag or container are usually designed in such a way that
container integrity is maintained in the dry state to
prevent egress of the contents when dry, but are adapted
for release of the container contents on exposure to a
washing environment, normally on immersion in an aqueous
solution.
Usually the container will be flexible, such as a bag or
pouch. The bag may be of fibrous construction coated with a
water impermeable protective material so as to retain the
contents, such as is disclosed in European published Patent
Application No. 0018678. Alternatively it may be formed of
a water-insoluble synthetic polymeric material provided
with an edge seal or closure designed to rupture in aqueous
media as disclosed in European published Patent Application
Nos. 0011500, 0011501, 0011502, and 0011968. A convenient
form of water frangible closure comprises a water soluble
adhesive disposed along and sealing one edge of a pouch
formed of a water impermeable polymeric film such as
polyethylene or polypropylene.
In a variant of the bag or container form, laminated sheet
products can be employed in which a central flexible layer
is impregnated and/or coated with a composition and then
one or more outer layers are applied to produce a fabric-
WO 94/15010 ~1~~~~~ PCT/US93I06818
42
like aesthetic effect. The layers may be sealed together
so as to remain attached during use or may separate on
contact with water to facilitate the release of the coated
or impregnated material.
An alternative laminate form comprises one layer embossed
or deformed to provide a series of pouch-like containers
into each of which the detergent components are deposited
in measured amounts, with a second layer overlying the
first layer and sealed thereto in those areas beteen the
pouch-like containers where the two layers are in contact.
The components may be deposited in particulate, paste or
molten form and the laminate layers should prevent egress
of the contents of the pouch-like containers prior to their
addition to water. The layers may separate or may remain
attached together on contact with water, the only
requirement being that the structure should permit rapid
release of the contents of the pouch-like containers into
solution. The number of pouch-like containers per unit
area of substrate is a matter of choice but will normally
vary between 500 and 25,000 per square metre.
Suitable materials which can be used for the flexible
laminate layers in this aspect of the invention include,
among others, sponges, paper and woven and non-woven
fabrics.
However the preferred means of carrying out the washing
process is to introduce the composition into the liquid
surrounding the fabrics that are in the drum via a reusable
dispensing device having walls that are permeable to liquid
but impermeable to the solid composition.
Devices of this kind are disclosed in European Patent
Application Publication Nos. 0343069 & 0343070. The latter
Application discloses a device comprising a flexible sheath
in the form of a bag extending from a support ring defining
an orifice, the orifice being adapted to admit to the bag
r ~___~..,.~.... _ _..._ _
'" WO 94/15010 ~a.-'~~J~ ~; PCT/US93106818
43
sufficent product for one washing cycle in a washing cycle.
A portion of the washing medium f lows through the orif ice
into the bag, dissolves the product, and the solution then
passes outwardly through the orifice into the washing
medium. The support ring is provided with a masking
arrangement to prevent egress of wetted, undissolved,
product, this arrangement typically comprising radially
extending walls extending from a central boss in a spoked
wheel configuration, or a similar structure in which the
walls have a helical form.
Example
TAED powder was agglomerated and dried as described above
using Sokalan(R)CP45. The resultant dry agglomerate was
then spray-coated with a further quantity(25% by weight) of
Sokalan(R)P45 in a fluid bed. The height of the spray-
nozzle was adjusted so that it was above the highest
particles fluidised in the air-stream. To reduce the
tendency to cake and facilitate drying the temperature of
the fluidising air was raised to around 85 deg.C. When the
spray-on was complete the fluidisation with hot air was
continued until the residual moisture was below 5% (by
weight). The final dry agglomerate was then screened as
before to provide a material where 95% of the particles lay
between 1700 and 425 micrometers.
The agglomerate had the following composition:-
TAED: 76.8%
Sokalan(R)CP45: 18.60, and the mean coating level
determined by acid-base titration and calculated difference
was 10.4%.
Water/Misc: to 100%
WO 94/15010 ~1,~~58~ PCT/US93/06818
44
The composition was then separated into four classes of
particles and the meanc coating level was determined by
acid base titration and calculated difference.
Part. Size (micrometers) >1200 >850 >425 <425
mean coating 6.4 10.0 12.4 14.9
A reference TAED agglomerate was prepared by agglomerating the
same TAED powder with molten TAE25 as binder in the same mixing
device as above. Particles were then cooled and sized to the
same standards as above. Agglomerate composition was .
TAED 87.Oo
TAE25 ~ 13$
The detergent agglomerates were tested for colour damage
potential when incorporated into the following detergent matrix
(composition in parts by weight) .
C12 Linear Alkyl Benzene Sulfonate 9.0
Tallow Alkyl Sulphate 2.8
Dobanol 45E7 3.8
Zeolite A 20
Citrate 6.5
Carbonate 15.0
Silicate (Si02:Na20=2:1) 3.5
Perborate monohydrate 16.0
Sokalan(R) CP45* 4.0
Miscellaneous up to 100
* The detergent matrix already contains Sokalan(R) CP45 as a
co-builder, independently from the Sokalan(R) CP45 present in
the agglomerates.
The amount of agglomerate in the composition was such as to
provide an active level of 5% by weight of TAED versus the total
composition.
_.. _._._ .... _ _~ . _...~... ___.,..-__r__. ~..~ _ _.._._a
m WO 94115010 ~a"~s~~ PCTIUS93106818
The formulations containing the TAED agglomerates were subjected
to a full scale washing machine test using Miele automatic
washing machines (Model W754) set to the Short Wash cycle at
40°C.
Bleach-sensitive coloured fabric swatches were used, a 43 cm2
swatch being wrapped around the dispensing device in which 100g
of the formulation was added. In each machine, 3.3 kg of white
cotton bedsheets were used as ballast. 12 litres of water of
15o ppm hardness (expressed as CaC03) with a Ca:Mg ratio of 3:1
was fed to each machine. The swatches were made of 100%
lambswool woven fabric with purple 48 dye (Design No. W3970)
supplied by Borval Fabrics, Albert Street, Huddersfield, West
Yorkshire, England. 24 replicates of each treatment were
performed and the swatches were then graded visually for fabric
colour damage by an expert panel using the following grading
system.
Three coloured swatches demonstrating differing degrees of
colour damage are used as standards to establish a 4 point scale
in which 1 represents 'virtually no damage' and 4 represents
'very damaged'. The three standards are used to define the mid
points between the various descriptions of colour damage viz
1 virtually no damage
2 slight damage
3 damage
4 very damaged
Two expert panellists are used and their results are averaged.
Using this technique to compare colour damage resulting from use
of the formulations above the following results were obtained:
~..41~~4 .
WO 94/15010 PCT/US93/06818
46
Formulations o of swatches having grade Overall
Grade
1 2 3 4
(Reference) TAE25/TAED 13 17 58 12 2.69
(Invention): 33 33 30 4 2.05
Sokalan(R) CP45/TAED
It can be seen that the formulation incorporating the
agglomerate in accordance with the invention produces
appreciably less fabric colour damage than the reference
agglomerate. Further testing also confirmed that there
was no loss in bleaching performance for the optimised
product.
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