MICROCAPSULE INCORPORATION IN STRUCTURED LIQUID DETERGENTS

TECHNICAL FIELD
The present invention relates to an improved process for the incorporation of
microcapsules into a structured aqueous liquid detergent composition comprising
at least 30 wt% total surfactant.
BACKGROUND
It is desirable to use microcapsules in liquid detergents. Microcapsules having a
shell that protects the inner core contents may provide delayed release of their
contents and /or provide a stable formulation when their contents would otherwise
interact with the bulk liquid. Such microcapsules are well known in the detergent
field, and they have been proposed for inclusion in aqueous liquid detergent
compositions. The microcapsules are small enough to be usable in large
numbers and are generally not visible to the eye when introduced to the liquid.
Nevertheless, they may cause the liquid to become hazy. Some microcapsules
may be suspendible in an unmodified liquid. Others, with less closely matched
specific gravity, may require modification of the liquid via a thickening or
structuring system in order to avoid creaming or settling. Typical of such
microcapsules are perfume encapsulates with melamine formaldehyde shells as
described in US-A-5 066 4 19 . The microcapsules may alternatively contain other
liquid fabric treatment additives such as shading dye, lubricants etc. The contents
of the microcapsules are not important for the present invention.
When such microcapsules are added to concentrated surfactant solutions,
especially ones comprising an external structurant, such as hydrogenated castor
oil, or microfibrous cellulose, the microcapsules have been found to undergo
agglomeration into clumps during the incorporation step. These agglomerates
remain undispersed in the liquid. This increases visibility of the microcapsules. It
also causes uneven dosing of their contents per wash, as liquid is removed from
the container. Finally, if the agglomerated microcapsules survive up to the point
of deposition onto a fabric then the content of the microcapsules is overdosed at
that point and is unevenly distributed across the surface of the fabric. This could
cause unwanted effects such as fabric damage or the need to use more
microcapsules than would otherwise be necessary. Thus, it is highly desirable to
avoid substantial agglomeration of microcapsules in an aqueous liquid detergent.
By concentrated is meant a total surfactant content (including soap) of 30 wt% or
greater.
WO09135765A discloses a process for the manufacture of a structured liquid
detergent composition comprising a disperse-phase benefit agent which may be a
perfume microcapsule, micro-fibrous cellulose structurant, at least 5 wt% of
anionic surfactant and 25 to 55 wt% surfactant, the process comprising the steps
of preparation of a micro-fibrous cellulose premix using high shear mixing, (ii)
separate preparation of an aqueous surfactant mix, combination of the microfibrous
cellulose premix and the surfactant mix using high shear mixing, perfume
microcapsules may be post dosed to the resulting structured concentrated
surfactant structured liquid. The high shear mixing step is achieved using an in
line mixing process, such as by contacting the two process streams directly before
an in-line mixer. Microcapsule particle sizes are in the range of 5 to 50 microns,
preferably 10 to 30 microns.
Example 4 of WO091 35765A discloses details of perfume microcapsule addition.
1.5 wt% perfume encapsulates were added to an MFC structured liquid with a
surfactant level of 40 to 50 wt%. Addition was performed over 30 sec, using a
Heidolph stirrer, mixing continued for 5 min (if required). A Heidolph laboratory
mixer is an overhead driven propeller or paddle stirrer. It is not a static in-line
mixer. There is not any disclosure made of the quality of the liquid detergent
product made this way. We have now found that certain perfume microcapsules
tend to suffer from agglomeration problems when added this way.
In US2005026800A microcapsules are stirred into a laundry liquid detergent
prepared by combining an aqueous premix of heavy duty liquid (HDL) detergent
composition and a structuring premix. The HDL premix is prepared by combining
HDL components with water in a suitable vessel under suitable agitation and the
structuring agent premix is prepared by combining hydrogenated castor oil and
other structuring agent premix ingredients. The microcapsules are then slowly
added to the structured liquid while it was maintained under gentle agitation -
paragraph 88.
Other prior art either gives no details of the way microcapsules are added, or says
to stir them in.
It has been known from US2005026800A and other publications that
hydrogenated castor oil (HCO) can be used as an external structurant and
rheology modifier to stabilise such concentrated liquid detergents.
In WO201 0/034736 we describe the incorporation of perfume microcapsules into
a concentrated liquid detergent, structured using hydrogenated castor oil. The
microcapsules are added as an encapsulated perfume slurry and mixed in using a
paddle mixer. The formulations were assessed visually by eye, and by
microscopy, to identify if there was phase separation, or if the encapsulates were
still monodispersed. The compositions exhibited no loss or change of structuring
or encapsulate dispersal after being tested for 12 weeks at 5 °C, 12 weeks at 37
°C and 4 weeks at 50 °C. We have now found that although there is no further
agglomeration of the microcapsules, the initial dispersal by paddle mixer gives an
unacceptably high amount of substantially agglomerated perfume encapsulates.
These agglomerates appear not to redisperse. The presence of such
agglomerated material is undesirable, for the reasons explained previously.
It is an object of the present invention to provide an improved process for the
production of concentred externally structured liquid detergents, which liquid
detergents are capable of suspending microcapsules, for example encapsulated
fragrances, which are not visible to the eye.
SUMMARY OF THE INVENTION
According to the present invention there is provided a process for the
incorporation of microcapsules with anionic charge into a structured aqueous
concentrated liquid detergent comprising at least 30 wt%, preferably at most 65
wt%, total surfactant of which at least 5 wt% based on the total composition is
anionic surfactant, including soap, and an external structurant, the process
comprising the combining of two premixes; Premix A which is the structured
aqueous concentrated liquid detergent composition without microcapsules and
Premix B which comprises an aqueous dispersion of the microcapsules with
anionic charge, characterised in that:
Premix B is a slurry of microcapsules with a maximum viscosity at 25°C of 100
mPas and at least 90 wt% of the microcapsules having a particle size in the range
5 to 40 microns, preferably 5 to 30 microns, and that
Premix B is added to Premix A and the resulting combined mixture is passed
through a static in-line mixer with an energy input of from 20 to 500 J/kg to form,
immediately after the mixer, a structured liquid comprising less than 10%, based
on the total number of groups of microcapsules, agglomerated groups of
microcapsules, an agglonnerated group of microcapsules being defined as a group
having more than 5 microcapsules grouped together.
Preferably the maximum viscosity of the Premix B is 50 mPas, more preferably 20
mPas, even more preferably 15 mPas.
By agglomerated we mean that more than 5 microcapsules are grouped together.
This is determined, for example, by taking a photomicrograph of the liquid and
counting the number of groups of microcapsules present in the form of groups of
1, 2 3 4 or 5 microcapsules and also counting the number of groups of
microcapsules present in the form of agglomerates of more than 5 microcapsules,
which we define as being agglomerated microcapsules. If more than 10% of the
groups are in the form of such agglomerated microcapsules then the
microcapsules are too agglomerated to be within the scope of this invention.
To obtain the low viscosity of Premix B it may be necessary to reduce the
viscosity of the raw material slurry concentrate of microcapsules. This can be
done, for example, by dilution with water, if necessary.
The microcapsule slurry can be added to the main liquid by either in line injection
or pouring into the vessel whilst mixing. The mixture is then passed through an in
line static mixer that applies enough energy to break the agglomerates whilst
avoiding rupture of individual microcapsules and retention of the liquid structure.
Surprisingly, the resulting structured liquid is highly effective at preventing further
agglomeration of the microcapsules over time.
The external structurant is preferably hydrogenated castor oil (castor wax, or
trihydroxystearin). The external structurant may alternatively be another fibrous
agent, such as microfibrous cellulose or any other type of external structurant.
The microcapsules comprise a solid shell. We have found that the agglomeration
problem seems to be restricted to microcapsules carrying an anionic charge.
Microcapsules with a cationic charge may be added into concentrated liquids
without formation of agglomerates and therefore without the need for the process
of the present invention. Of course it is still possible to pass a mixture comprising
cationic microcapsules through an in-line static mixer to disperse the
microcapsules, if desired.
Most preferably, the microcapsule has a melamine formaldehyde shell. Other
suitable shell material may be selected from (poly)urea, (poly)urethane, starch/
polysaccharide and aminoplasts.
The microcapsules may be perfume encapsulates. We have found that inclusion
of microcapsules of smaller diameter makes the agglomeration problem worse.
The microcapsules have a diameter less than or equal to 40 micrometers. This
upper size ensures that even if small cluster of up to 5 particles form they should
remain substantially invisible. Most preferred are microcapsules with diameters.
It is advantageous to have a very narrow particle size distribution, for instance 90
wt% of microcapsules in the range 8 to 11 microns. This minimises the amount of
potentially high surface area material that may act as adhesive and bind larger
particles together.
Microcapsules in the range 2 to 5 microns cannot be dispersed so effectively
using the process according to the invention due to the high surface area of the
smaller particles. In contrast, microcapsules greater than 40 microns generally
require no additional processing as the smaller total surface area is sufficient to
prevent substantial agglomeration without need for the increased energy input
from an in-line static mixer. Nevertheless, the process may be used for larger
particles, if desired.
The process is most effective for microcapsules in the range 5 to 30 microns.
Removal of microcapsules ranging from 0.1 to less than 1 micron improves the
microcapsule dispersion. This is thought to be due to the reduction of high
surface area material.
Once the microcapsules have been incorporated into the structured liquid and
dispersed by the in line mixer, the structure is very effective at preventing any
agglomeration, even in the presence of high levels of surfactant.
The process may be used to make externally structured concentrated liquid
compositions comprising at least 30 wt% surfactant including anionic surfactant
(any soap being included in the calculation and being an anionic surfactant)
comprising 0.1 to 2.0 wt% microcapsules wherein the ratio microcapsules in
groups of 5 or less to agglomerated microencapsulates (in groups of 5 or more) is
more than 9:1 .
When hydrogenated castor oil is used as the external structurant, it is suitably
present at a level of from 0.1 5 to 0.5 wt% of the total composition. Preferably, it
has a dendritic structure wherein the fibres are entangled and the minor
dimension of the fibres is at most 40 nm.
DETAILED DESCRIPTION OF THE INVENTION
All percentages mentioned herein are by weight calculated on the total
composition, unless specified otherwise.
Premix A
Although, in principle, Premix A may be formed using any of the processes of the
prior art, or any other suitable process, when using hydrogenated castor oil as
external structurant it is preferable to employ a process such as that described in
WO20 10/034736, as also described below.
If using microfibrous cellulose it is preferred to employ an adaptation of the
process described in WO091 35765A.
External structurant
The preferred external structurant is hydrogenated castor oil. As an alternative,
microfibrous cellulose may be used, this material and its properties and use as an
external structurant are described in the published literature, for example in
WO09135765A (Unilever), and US20081 08541A (C P Kelco).
Hydrogenated Castor Oil
Castor oil, also known as ricinus oil, is a vegetable oil obtained from the bean of
the castor plant (Ricinus communis). Castor oil is a colourless to very pale yellow
liquid with mild or no odour or taste. It is a triglyceride in which approximately
ninety percent of fatty acid chains are ricinoleic acid ( 12-hydroxy-9-cisoctadecenoic
acid). Oleic and linoleic acids are the other significant components.
The controlled hydrogenation of castor oil yields fully hydrogenated castor oil,
which is used in the method and products according to the present invention. At
room temperature, hydrogenated castor oil is a hard white wax that melts at a
temperature of about 86-88°C. Suppliers are, for example, Hindustan Unilever,
supplying flakes or granules, Cognis (powder), Vertellus (flakes) or Elementis
(flakes or granules), or any mixture thereof. A hydrogenated castor oil suitable in
the present invention is, for example, Thixcin® R available from Elementis.
Structuring Process
When using hydrogenated castor oil as the external structurant PREMIX A, may
be produced using a process, comprising the following steps:
a) preparation of a first premix by adding surfactants and a base to water
under agitation at a temperature of at least 55°C, preferably at a temperature from
55 to 70°C, more preferably from 60 to 65°C, and most preferably at about 65°C,
having a pH from 7.5 to 11, preferably from 8 to 10;
b) preparation of a second premix by adding hydrogenated castor oil to a
liquid non-aqueous organic solvent at a temperature of at least 70°C, preferably at
a temperature from 70 to 75°C, under agitation to dissolve the hydrogenated
castor oil in the liquid non-aqueous organic solvent, wherein the non-aqueous
organic solvent preferably comprises free fatty acid, or nonionic surfactant, or
mixtures thereof;
c) addition of the second premix from step b) to the first premix from step a) at
a temperature of at least 55°C under mixing, preferably at a temperature from 55
to 70°C, more preferably from 55 to 65°C, most preferably from 60 to 65°C,
at a weight ratio of b) to a) of from 1:40 to 1:1 0, preferably from :30 to 1:1 5, more
preferably at a ratio of about :20; whereby the hydrogenated castor oil remains in
solution;
d) cooling of the mix of step c) to a temperature below 50°C, preferably below
40°, more preferably below 30°C, and subsequently storing this mix until the
hydrogenated castor oil has crystallised from solution.
Preferably in step a) the concentration of surfactants is from 20 to 65 wt%, more
preferably from 25 to 60 wt%, and mostly preferably from 25 to 45 wt% of the total
mix in this step. In step a), the surfactants preferably comprise synthetic anionic
and/or nonionic surfactants. More preferably, the surfactants in step a) comprise
the synthetic anionic surfactant linear alkylbenzene sulphonate (LAS). The pH of
the premix in step a) is preferably from 9 to 10 .
The first premix in step a) comprises surfactants and a base in water, and
preferably also a hydrotrope. A hydrotrope is a compound that solubilises
hydrophobic compounds in aqueous solutions. Typically, hydrotropes consist of a
hydrophilic part and a hydrophobic part, however the hydrophobic part is too small
to cause spontaneous self-aggregation and so they do not form micelles like
surfactants. Hydrotropes are used in detergent formulations to allow more
concentrated formulations of surfactants. Suitable hydrotropes are, for example,
glycerol and propylene glycol. Preferably, the first premix in step a) is a
transparent liquid at the prevailing temperature of step c). The base in the premix
in step a) preferably comprises an alkali metal hydroxide or triethanolamine, more
preferably the neutralising agent comprises sodium hydroxide, triethanolamine or
mixtures thereof. Typically, the premix in step a) is a micellar solution of the
surfactants in water.
A second premix is prepared containing hydrogenated castor oil dissolved in a
liquid non-aqueous organic solvent at a temperature of at least 70°C, preferably
from 70 to 75°C. Preferably the solvent comprises free fatty acid, or nonionic
surfactant, or a mixture of these. More preferably, the solvent comprises a free
fatty acid and most preferably, the free fatty acid comprises linear alkyl saturated
C 12-C1 8 fatty acid. Free water is not added to the solvent in the vessel in this
step b). Preferably, the second premix is made under low shear conditions; more
preferably, only gentle mixing is applied. This has as an advantage that only low
energy input is required when mixing the second premix. Suitably this second
premix in step b) is a transparent liquid at the prevailing temperatures in this step
b).
Preferably the concentration of hydrogenated castor oil in the second premix is
such that the concentration in the final liquid detergent composition obtainable by
the method of the invention is from 0.1 5 to 0.5 wt% of the composition, preferably
from 0.1 5 to 0.35 wt%, even more preferably from 0.2 to 0.35 wt%, and most
preferably from 0.22 to 0.28 wt% of the total composition. The concentration of
hydrogenated castor oil in the second premix in step b) is preferably from 1.5 to
20 wt% of the premix, more preferably from 1.5 to 10 wt%, even more preferably
from 1.7 to 5 wt%, and most preferably from 3.4 wt% to 5 wt% of the premix.
Preferably, the second premix comprises only solvent and hydrogenated castor
oil, wherein the solvent preferably comprises free fatty acid, or nonionic surfactant,
or mixtures thereof, most preferably the solvent is free fatty acid, for the reasons
explained below in relation to step c).
In the method according to the invention, in step c) the second premix is added to
the first premix under agitation, wherein the weight ratio of the second and first
premix is from 1:40 to 1:1 0, preferably from 1:30 to 1:1 5, and more preferably at
about 1:20. Most preferred the second premix constitutes less than 6 wt% of the
total formulation, most preferred about 5 wt% of the total formulation. The
temperature in step c) is at least 55°C, preferably between 55 and 70°C, more
preferably between 55 and 65°C, most preferred between 60 and 65°C.
When the solvent in the second premix in step b) comprises free fatty acid, the
base in the first premix acts as neutralising agent for the fatty acid, and soap is
formed by mixing the first and second premix in step c). This formation of soap
leads to complete or partial elimination of the solvent for the hydrogenated castor
oil and this process is thought to act as a seed for its subsequent crystallisation to
the dendritic structure. A similar effect can be obtained by careful selection of
nonionic surfactant solution that will have a phase change on addition to anionic
surfactant solution, but this type of physical phase change is less preferred than
the chemical phase change due to the neutralisation of the free fatty acid solvent.
In step c) the first and second premixes are combined under gentle mixing.
Generally, the mix in step c) is clear at the prevailing temperature in step c), which
is at least 55°C, preferably from 55 to 70°C, indicating that the second premix
suitably completely dissolves in the first premix. Usually at this temperature, all
ingredients are in solution and the hydrogenated castor oil does not crystallise.
By the gentle mixing in step c), the solubilised hydrogenated castor oil is
homogeneously mixed before the crystallization process commences.
In step d) the mix from step c) is cooled to a temperature below 50°C, preferably
below 40°, more preferred below 35°C, even more preferred below 30°C.
Subsequently this mix is stored until the hydrogenated castor oil has crystallised
from solution. The skilled person is able to determine when the hydrogenated
castor oil has crystallised, as the crystallisation of the hydrogenated castor oil can
be visually observed by the liquid becoming cloudy. Otherwise by conventional
light microscopy it can be observed whether crystals of hydrogenated castor oil
have formed. Preferably, this cooling step d) is carried out while the mix is gently
mixed, at low shear conditions. In this case, low shear means that the shear is
insufficient to break up the emerging dendritic structure.
In a preferred method, in step d) the mix of step c) is cooled to a temperature
below 50°C at a cooling rate of maximally 1°C per minute. Preferably in step d)
the mix of step c) is cooled to a temperature below 40°C, more preferably 30°C, at
a cooling rate of maximally 1°C per minute, preferably maximally 0.7°C per
minute, even more preferably maximally 0.5°C per minute, mostly preferably
maximally 0.4°C per minute. When applying this preferred cooling step d), the
hydrogenated castor oil present in the premix suitably starts to crystallise during
the cooling step, at a temperature below 55°C.
In another preferred method, in step d) the mix of step c) is cooled to a
temperature below 40°C within 5 minutes, followed by storing this mix at a
temperature below 40°C for at least 5 minutes. Preferably in step d) the mix of
step c) is cooled to a temperature below 35°C within 5 minutes, more preferably
within 3 minutes, followed by storing this mix at a temperature below 35°C for at
least 5 minutes. More preferably in step d) the mix of step c) is cooled to a
temperature below 30°C within 5 minutes, most preferably within 3 minutes,
followed by storing this mix at a temperature below 30°C for at least 5 minutes.
Even more preferably, the mix of step c) is cooled to a temperature below 40°C
within 3 or even 2 minutes, followed by storage at a temperature below 40°C for at
least 5 minutes. Most preferably, the mix of step c) is cooled to a temperature
below 30°C within 3 or even 2 minutes, followed by storage at a temperature
below 30°C for at least 5 minutes. In another preferred embodiment, the mix is
stored for at least 8 minutes, or more preferably, at least 10 minutes at the
prevailing temperature after the cooling step has taken place. When applying this
rapid cooling step d), the hydrogenated castor oil present in the premix suitably
starts to crystallise during the storage of the mix after the rapid cooling.
An example of such a rapid cooling process is flash cooling in a plate heat
exchanger, wherein the mixture is cooled to below 30°C within a period of about 1
minute. When such a rapid cooling process is applied, the mixture will be kept at
the temperature below 40°C for a period of at least 5 minutes. In this holding
period the temperature of the mix is kept constant below 40°C, and crystallisation
of the hydrogenated castor oil will occur at the temperature at which the premix is
kept after the rapid cooling has taken place.
In this step d) an opacified non-Newtonian liquid is obtained, which preferably has
a shear thinning profile to provide a pourable liquid easily dispensed into a
washing machine. The solubilised hydrogenated castor oil may self-assemble into
a dendritic structure. A dendritic structure is a highly branched structure of solid
material having a core with branches extending from that core. The dendritic
structure seems to be formed by a series of nucleations on cooling the mix in step
d), followed by crystal growth from these nucleation sites leading to the formation
of the dendrites. The nucleating site can be described as the core of the
dendrimer. Suitably, the hydrogenated castor oil grows out into a threedimensional
branched structure from this core throughout the formulation, leading
to a three-dimensional scaffold. The hydrogenated castor oil, in the form of
dendrimers, forms a structuring network, where the dimensions of dendrimers are
preferably micron-sized (up to about 100 micrometer). The dendrimers form a
highly-tangled fibrous network. The branches (or fibres) of a dendrimer typically
have a thickness from 20 to 40 nanometre and typically extend up to more than 10
micrometer. These branches of the dendrimers are relatively long and thin and
have an aspect ratio of the order of 1000:1 . In comparison the prior art thread-like
structuring system formed by crystallising from an emulsion, as described in EP 1
502 944 and elsewhere, has an aspect ratio of up to 200:1 . The minor dimension
of the particles produced by the solvent process is also much smaller than that
obtained by the aqueous emulsion process. According to EP 1 502 944, the
preferred minor dimension for the thread-like structurant is from 5 to 15
micrometres. Even at the lower extreme of 1 micrometre mentioned in EP1 502
944 the fibres of the prior art thread-like structures are more than twice as thick as
the dendrimers formed by the solvent process. The crystallisation of the
hydrogenated castor oil causes the formulation to become translucent due to the
size of the dendritic structure interfering with the transmittance of the light through
the formulation. The microstructure of the dendrimers and the prior art thread-like
structures are easily distinguished by microscopic examination as well as by their
rheological and suspending properties.
Water
The invention is particularly suited to the addition of microcapsules to
compositions comprising less than 40 wt% water. This low level of water makes
dispersal of the microcapsules more difficult when coupled with the high active
levels of the compositions of the invention. The invention is, however, also
applicable to high surfactant composition with higher water levels.
Surfactants
The liquid detergent compositions made using the process of the invention
preferably comprise from 30 to 65wt%, more preferred from 30 to 60wt%, and
most preferably from 35 to 45% of a surfactant, preferably selected from anionic,
nonionic, cationic, zwitterionic active detergent materials or mixtures thereof. In
the context of the present invention, anionic surfactants include both soap and
synthetic anionic surfactants. The minimum level of anionic surfactant is 5 wt%.
In general, the surfactants of the surfactant system may be chosen from the
surfactants described in 'Surface Active Agents' Vol. 1, by Schwartz & Perry,
Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958, in the
current edition of 'McCutcheon's Emulsifiers and Detergents' published by
Manufacturing Confectioners Company or in Tenside Taschenbuch', H. Stache,
2nd Edn., Carl Hauser Verlag, 1981 .
A preferred component of the liquid detergent compositions according to the
invention is soap (salt of fatty acid). Preferably, the organic non-aqueous solvent
used in step b) of the method of the invention comprises a fatty acid. Preferably
the fatty acid comprises linear alkyl saturated C 12-C1 8 fatty acids. Examples of
fatty acids suitable for use of the present invention include pure or hardened fatty
acids derived from palmitoleic, safflower, sunflower, soybean, oleic, linoleic,
linolenic, ricinoleic, rapeseed oil or mixtures thereof. An example of a preferred
fatty acid is a hydrogenated coconut fatty acid, for example Prifac 5908 (supplied
by Uniqema, Gouda, Netherlands). Mixtures of saturated and unsaturated fatty
acids can also be used herein.
It will be recognised that the fatty acid will be present in the (final) liquid detergent
composition primarily in the form of a soap. Suitable cations include sodium,
potassium, ammonium, monoethanol ammonium diethanol ammonium, triethanol
ammonium, tetraalkyl ammonium, e.g. tetra methyl ammonium up to tetradecyl
ammonium cations.
The amount of fatty acid will vary depending on the particular characteristics
desired in the final liquid detergent composition. Preferably, 0 to 30%, more
preferably 1 to 20% most preferably 2 to 10 wt% of fatty acid is present in the
liquid detergent composition according to the invention.
Mixtures of synthetic anionic and nonionic surfactants are especially useful in the
invention.
Nonionic detergent surfactants are well-known in the art. They normally consist of
a water-solubilising polyalkoxylene or a mono- or di-alkanolamide group in
chemical combination with an organic hydrophobic group derived, for example,
from alkylphenols in which the alkyl group contains from about 6 to about 12
carbon atoms, dialkylphenols in which primary, secondary or tertiary aliphatic
alcohols (or alkyl-capped derivatives thereof), preferably having from 8 to 20
carbon atoms, monocarboxylic acids having from 10 to about 24 carbon atoms in
the alkyl group and polyoxypropylene. Also common are fatty acid mono- and
dialkanolamides in which the alkyl group of the fatty acid radical contains from 10
to about 20 carbon atoms and the alkyloyi group having from 1 to 3 carbon atoms.
In any of the mono- and di-alkanolamide derivatives, optionally, there may be a
polyoxyalkylene moiety joining the latter groups and the hydrophobic part of the
molecule. In all polyalkoxylene containing surfactants, the polyalkoxylene moiety
preferably consists of from 2 to 20 groups of ethylene oxide or of ethylene oxide
and propylene oxide groups. Amongst the latter class, particularly preferred are
those described in EP 225 654 A. Also preferred are those ethoxylated nonionics
which are the condensation products of fatty alcohols with from 9 to 18 carbon
atoms condensed with from 3 to 11 moles of ethylene oxide. Examples of these
are the condensation products of C9-1 8 alcohols with on average 3 to 9 moles of
ethylene oxide. Preferred for use in the liquid detergent composition of the
invention are C 12-C1 5 primary, linear alcohols with on average 3 to 9 ethylene
oxide groups.
A preferred nonionic surfactant is a C 12-C1 8 ethoxylated alcohol, comprising 3 to
9 ethylene oxide units per molecule. More preferred are C 12-C1 5 primary, linear
ethoxylated alcohols with on average 5 to 9 ethylene oxide groups, more
preferably on average 7 ethylene oxide groups.
Suitable synthetic anionic surfactants for the detergent compounds which may be
used are usually water-soluble alkali metal salts of organic sulphates and
sulphonates having alkyi radicals containing from about 8 to about 22 carbon
atoms, the term alkyi being used to include the alkyi portion of higher acyl
radicals, including alkyi sulphates, alkyi ether sulphates, alkaryl sulphonates,
alkanoyl isethionates, alkyi succinates, alkyi sulphosuccinates, N-alkoyl
sarcosinates, alkyi ether carboxylates, alpha-olefin sulphonates and acyl methyl
taurates, especially their sodium, magnesium ammonium and mono , di- and
triethanolamine salts. The alkyi and acyl groups generally contain from 8 to 22
carbon atoms, preferably 8 to 18 carbon atoms, still more preferably 12 to 15
carbon atoms and may be unsaturated. The alkyi ether sulphates and alkyi ether
carboxylates may contain from one to ten ethylene oxide or propylene oxide units
per molecule, and preferably contain one to three ethylene oxide units per
molecule.
Examples of suitable synthetic anionics include sodium lauryl sulphate, sodium
lauryl ether sulphate, ammonium lauryl sulphosuccinate, ammonium lauryl
sulphate, ammonium lauryl ether sulphate, sodium cocoyl isethionate, sodium
lauroyl isethionate, and sodium N-lauryl sarcosinate. Mostly preferred the
synthetic anionic surfactants comprise the synthetic anionic surfactant linear
alkylbenzene sulphonate (LAS). Another synthetic anionic surfactant suitable in
the present invention is sodium alcohol ethoxy-ether sulphate (SAES), preferably
comprising high levels of sodium C 12 alcohol ethoxy-ether sulphate.
Preferred surfactant systems are mixtures of synthetic anionic with nonionic
detergent active materials and additionally cationic or amphoteric surfactant.
Especially preferred is a surfactant system that is a mixture of alcohol ethoxyether
sulphate (AES) and a C 12-C1 5 primary ethoxylated alcohol 3-9 EO
ethoxylate and a quaternary ammonium cationic surfactant.
Preferred surfactant systems are mixtures of synthetic anionic with nonionic
detergent active materials and soap, additionally with cationic or amphoteric
surfactant. Synthetic anionic surfactants can be present for example in amounts
in the range from about 5% to about 70wt% of the total surfactant material.
In a preferred embodiment of the invention, the detergent compositions also
comprises a cationic surfactant or an amphoteric surfactant, wherein the cationic
or amphoteric surfactant is present in a concentration of 1 to 20%, preferably 2 to
15% more preferably 3 to 12wt% of the total surfactant.
Suitable cationic surfactants that may be used are, substituted or unsubstituted,
straight-chain or branched quaternary ammonium salts. Preferably the cationic
surfactant is of the formula:
R 1R2R3R4N+ Xwherein
R 1 is C8-C22-alkyl, C8-C22-alkenyl, C8-C22-alkylalkenylamidopropyl or
C8-C22-alkoxyalkenylethyl, R2 is C 1-C22-alkyl, C2-C22-alkenyl or a group of the
formula -A-(OA)n-OH, R3 and R4 are C 1-C22-alkyl, C2-C21 -alkenyl or a group of
the formula -A-(OA)n-OH, A is -C2H4- and/or -C3H6- and n is a number from 0 to
20 and X is an anion. A commercially available and preferred example of this type
of cationic surfactant is a compound of the formula above, where R 1 is a C 12/14
alkyl group, R2 is a group of the formula -A-(OA)n-OH, wherein A is -C2H4- and n
is nil, and R3 and R4 are both -CH3 (i.e. C 1-alkyl). This type of cationic surfactant
is commercially available. E.g. from Clariant under the name Praepagen HY®.
Typical examples of suitable amphoteric and zwitterionic surfactants are alkyl
betaines, alkylamido betaines, amine oxides, aminopropionates, aminoglycinates,
amphoteric imidazolinium compounds, alkyldimethylbetaines or
alkyldipolyethoxybetaines.
Optional ingredients
A wide variety of optional ingredients useful in detergent compositions can be
included in the compositions herein, including other active ingredients,
hydrotropes, processing aids, dyes or pigments, carriers, detergency builders,
antioxidants, fragrances, detersive enzymes, suds suppressors, chelating agents,
clay soil removal/ anti-redeposition agents, brighteners, fabric softeners, dye
transfer inhibition agents, bleaches and the like; some of which are describes in
more detail below.
Carriers
Liquid detergent compositions of the invention may contain various solvents as
carriers. Low molecular weight primary or secondary alcohols exemplified by
methanol, ethanol, propanol, and isopropanol are suitable. Other suitable carrier
materials are glycols, such as mono-, di-, tri-propylene glycol, glycerol and
polyethylene glycols (PEG) having a molecular weight of from 200 to 5000. The
compositions may contain from 1% to 50%, typically 5% to 30%, preferably from
2% to 10%, by weight of such carriers.
Detergencv builder
One or more detergency builders may be present in the liquid detergent
composition.
Examples of suitable organic detergency builders, when present, include the
alkaline metal, ammonium and substituted ammonium polyacetates, carboxylates,
polycarboxylates, polyacetyl carboxylates, carboxymethyloxysuccinates,
carboxymethyloxymalonat.es, ethylene diamine-N,N-disuccinic acid salts,
polyepoxysuccinates, oxydiacetates, triethylene tetramine hexa-acetic acid salts,
N-alkyl imino diacetates or dipropionates, alpha sulpho- fatty acid salts, dipicolinic
acid salts, oxidised polysaccharides, polyhydroxysulphonat.es and mixtures
thereof.
Specific examples include sodium, potassium, lithium, ammonium and substituted
ammonium salts of ethylenediamino-tetraacetic acid, nitrilo-triacetic acid,
oxydisuccinic acid, melitic acid, benzene polycarboxylic acids and citric acid,
tartrate mono succinate and tartrate di succinate.
Antioxidants
The liquid detergent compositions obtainable by the method according to the
present invention preferably comprise from 0.005 to 2 wt% of an anti-oxidant.
Preferably, the anti-oxidant is present at a concentration in the range of 0.01 to
0.08 wt%.
Anti-oxidants are substances as described in Kirk-Othmer (Vol 3, pg 424) and in
Uhlmans Encyclopedia (Vol 3, pg 9 1) . One class of anti-oxidants that could be
used in the present invention is alkylated phenols having the general formula:
wherein R is C1-C22 linear or branched alkyi, preferably methyl or branched C3-
C6 alkyi; C3-C6 alkoxy, preferably methoxy; R 1 is a C3-C6 branched alkyi,
preferably tert-butyl; x is 1 or 2 . Hindered phenolic compounds are a preferred
type of alkylated phenols according to this formula. A preferred hindered phenolic
compound of this type is 2, 6-di-tert-butyl-hydroxy-toluene (BHT).
A further class of anti-oxidants which could be suitable for use in the present
invention is a benzofuran or benzopyran derivative having the formula:
R7
wherein R 1 and R2 are each independently alkyi or R 1 and R2 can be taken
together to form a C5-C6 cyclic hydrocarbyl moiety; B is absent or CH2; R4 is C 1-
C6 alkyi; R5 is hydrogen or -C(O)R3 wherein R3 is hydrogen or C 1-C1 9 alkyi; R6
is C 1-C6 alkyi; R7 is hydrogen o C1-C6 alkyi; X is CH2OH, or CH2A wherein A
is a nitrogen comprising unit, phenyl, or substituted phenyl. Preferred nitrogen
comprising A units include amino, pyrrolidino, piperidino, morpholino, piperazino,
and mixtures thereof.
Anti-oxidants such as tocopherol sorbate, butylated hydroxy benzoic acids and
their salts, gallic acid and its alkyi esters, uric acid and its salts and alkyi esters,
sorbic acid and its salts, and dihydroxy fumaric acid and its salts may also be
used.
Fragrances
The liquid detergent compositions obtainable by the method according to the
present invention preferably comprise from 0.001 to 3 wt% of the total composition
of a perfume composition, preferably from 0.01 to 2 wt% of the total composition.
Said perfume composition preferably comprises at least 0.01 wt% based on the
liquid composition of a perfume component selected from terpenes, ketones,
aldehydes and mixtures thereof. The perfume composition may fully consist of
the perfume component but generally the perfume composition is a complex
mixture of perfumes of various differing perfume classifications. In this regard, the
perfume composition preferably comprises at least 0.1 %, more preferably at least
1.0%, still more preferably at least 5 wt% of the perfume component.
Detersive enzymes
'Detersive enzyme', as used herein, means any enzyme having a cleaning, stain
removing or otherwise beneficial effect in a laundry application. Suitable enzymes
that could be used in the composition of the present invention include proteases,
amylases, lipases, cellulases, peroxidases, and mixtures thereof, of any suitable
origin, such as vegetable, animal bacterial, fungal and yeast origin. Preferred
selections are influenced by factors such as pH-activity, thermostability, and
stability to active bleach detergents, builders and the like. In this respect bacterial
and fungal enzymes are preferred such as bacterial proteases and fungal
cellulases. Enzymes are included in the present detergent compositions for a
variety of purposes, including removal of protein-based, saccharide-based, or
triglyceride-based stains, for the prevention of refugee dye transfer, and for fabric
restoration.
Enzymes are normally incorporated into detergent composition at levels sufficient
to provide a "cleaning-effective amount". The term "cleaning effective amount"
refers to any amount capable of producing a cleaning, stain removal, soil removal,
whitening, or freshness improving effect on the treated substrate. In practical
terms for normal commercial operations, typical amounts are up to about 50 mg
by weight, more typically 0.01 mg to 30 mg, of active enzyme per gram of
detergent composition. Stated otherwise, the composition of the invention may
typically comprise from 0.001 to 3%, preferably from 0.01 to 1 wt% of a
commercial enzyme preparation.
Protease enzymes are usually present in such commercial preparations at levels
sufficient to provide from 0.005 to 0.1 Anson units (AU) of activity per gram of
composition. Higher active levels may be desirable in highly concentrated
detergent formulations. Suitable examples of proteases are the subtilisins that are
obtained from particular strains of B. subtilis and B. licheniformis. One suitable
protease is obtained from a strain of Bacillis, having maximum activity throughout
the pH-range of 8-1 2, developed and sold as Esperase® by NovoZymes of
Denmark.
Other suitable proteases include Alcalase® and Savinase® Relase® from
Novozymes and Maxatase® from International Bio-Synthetics, Inc., The
Netherlands.
The composition may additionally comprise enzymes as found in WO 01/00768.
Suitable lipase enzymes for use in the composition of the invention include those
produced by microorganisms of the Pseudomonas group, such as Pseudomonas
stutzeri ATCC 19.1 54, as disclosed in GB 1,372,034. A very suitable lipase
enzyme is the lipase derived from Humicola lanuginosa and available from
Novozymes under the tradename Lipex®.
Preferably enzymes are added to the compositions after the cooling step d) in the
preferred process to form PREMIX A.
Suds Suppressors
Compounds for reducing or suppressing the formation of suds can be
incorporated into the compositions of the present invention. Suds suppression
can be of particular importance in the so-called "high concentration cleaning
process" as described in US-A-4,489,455 and US-A-4,489,574 and in frontloading
European-style washing machines.
A wide variety of materials may be used as suds suppressors, and suds
suppressors are well known to those skilled in the art. See, for example, Kirk
Othmer Encyclopedia of Chemical Technology, Third Edition, Volume 7, pages
430- 447 (John Wiley & Sons, Inc., 1979). One category of suds suppressor of
particular interest encompasses monocarboxylic fatty acid and soluble salts
therein. See US-A-2,954,347. The monocarboxylic fatty acids and salts thereof
used as suds suppressor typically have hydrocarbyl chains of 10 to about 24
carbon atoms, preferably 12 to 18 carbon atoms. Suitable salts include the alkali
metal salts such as sodium, potassium, and lithium salts, and ammonium and
alkanolammonium salts. Favourable anti-foaming results were obtained with fatty
acid mixtures comprising lauric acid, myristic acid, palmitic acid, stearic acid,
arachidic acid and behenic acid. A preferred saturated fatty acid of this type is
Prifac 5908 (trademark ex Uniqema).
The detergent compositions herein may also contain non-surfactant suds
suppressors. These include, for example: high molecular weight hydrocarbons
such as paraffin, fatty acid esters (e.g., fatty acid triglycerides), fatty acid esters of
monovalent alcohols, aliphatic C 18-C40 ketones (e.g., stearone), etc.
The preferred category of non-surfactant suds suppressors comprises silicone
suds suppressors. This category includes the use of polyorganosiloxane oils,
such as polydimethylsiloxane, dispersions or emulsions of polyorganosiloxane oils
or resins, and combinations of polyorganosiloxane with silica particles wherein the
polyorganosiloxane is chemisorbed or fused onto the silica. Silicone suds
suppressors are well known in the art and are, for example, disclosed in US-A-
4,265,779.
For any detergent compositions to be used in automatic laundry washing
machines, suds should not form to the extent that they overflow the washing
machine.
Suds suppressors, when utilized, are preferably present in a "suds suppressing
amount. By "suds suppressing amount" is meant that the formulator of the
composition can select an amount of this suds controlling agent that will
sufficiently control the suds to result in a low-sudsing laundry detergent for use in
automatic laundry washing machines. The compositions herein will generally
comprise from 0.1 % to about 5% of suds suppressor.
If high sudsing is desired, suds boosters such as the C10-C1 6 alkanolamides can
be incorporated into the compositions, typically at 1%- 10% levels. The C 10-C14
monoethanol and diethanol amides illustrate a typical class of such suds boosters.
If desired, soluble magnesium salts such as MgCI2, MgSO4, and the like, can be
added at levels of, typically, 0.1 %-2%, to provide additional suds and to enhance
grease removal performance.
Chelating Agents
The liquid detergent compositions herein may also optionally contain one or more
iron, copper and/or manganese chelating agents. Such chelating agents can be
selected from the group consisting of amino carboxylates, amino phosphonates,
polyfunctionally- substituted aromatic chelating agents and mixtures therein, all as
hereinafter defined.
If utilised, these chelating agents will generally comprise from about 0.1 % to about
10 wt% of the detergent compositions herein. More preferably, if utilised the
chelating agents will comprise from about 0.1 % to about 3.0 wt% of such
compositions.
Clay Soil Removal/Anti-redeposition Agents
The compositions of the present invention can also optionally contain watersoluble
ethoxylated amines having clay soil removal and antiredeposition
properties. Liquid detergent compositions typically contain about 0.01 % to about
5% of these agents.
One preferred soil release and anti-redeposition agent is ethoxylated
tetraethylenepentamine. Suitable ethoxylated amines are further described in USA-
4,597,898.
Other types of preferred antiredeposition agent include the carboxy methyl
cellulose (CMC) materials. These materials are well known in the art.
Brighteners
Any optical brighteners or other brightening or whitening agents known in the art
can be incorporated at levels typically from about 0.05% to about 1.2%, by weight,
into the liquid detergent compositions herein. Commercial optical brighteners,
which may be useful in the present invention, can be classified into subgroups,
which include, but are not necessarily limited to, derivatives of stilbene,
pyrazoline, cournarin, carboxylic acid, methinecyanines, dibenzothiphene-5,5-
dioxide, azoles, 5- and 6-membered- ring heterocycles, and other miscellaneous
agents. Examples of such brighteners are disclosed in "The Production and
Application of Fluorescent Brightening Agents", M. Zahradnik, Published by John
Wiley & Sons, New York ( 982).
Fabric Softeners
Various through-the-wash fabric softeners, especially the impalpable smectite
clays of US-A-4,062,647 as well as other softener clays known in the art, can
optionally be used typically at levels of from about 0.5% to about 10 wt% in the
present compositions to provide fabric softener benefits concurrently with fabric
cleaning. Clay softeners can be used in combination with amine and cationic
softeners as disclosed, for example, in US-A-4, 375,41 6 and US-A-4,291 ,071 .
Dye Transfer Inhibiting Agents
The compositions of the present invention may also include one or more materials
effective for inhibiting the transfer of dyes from one fabric to another during the
cleaning process. Generally, such dye transfer inhibiting agents include polyvinyl
pyrrolidone polymers, polyamine N-oxide polymers, copolymers of Nvinylpyrrolidone
and N- vinylimidazole, manganese phthalocyanine, peroxidases,
and mixtures thereof. If used, these agents typically comprise from about 0.01 %
to about 10 wt% of the composition, preferably from about 0.01 % to about 5%,
and more preferably from about 0.05% to about 2%.
Bleaches
Optionally, the composition according to the present invention may contain a
bleach or bleach system. This bleach or bleach system may be, for example: (a)
a peroxygen bleach species alone and/or in combination with a bleach activator
and/or a transition metal catalyst; and (b) a transition metal catalysts in a
composition substantially devoid of peroxygen species.
Bleaching catalysts for stain removal have been developed over recent years and
may be used in the present invention. Examples of transition metal bleaching
catalysts that may be used are found, for example, in: WO-01/48298, WO-
00/60045, WO-02/48301 , WO-00/29537 and WO-00/12667. The catalyst may
alternatively be provided as the free ligand that forms a complex in situ.
Bleach activators are also well known in the art. The exact mode of action of
bleach activators for peroxybleach compounds is not known, but it is believed that
peracids are formed by reaction of the activators with the inorganic peroxy
compound, which peracids then liberate active-oxygen by decomposition. They
are generally compounds which contain N-acyl or O-acyl residues in the molecule
and which exert their activating action on the peroxy compounds on contact with
these in the washing liquor.
Typical examples of activators within these groups are polyacylated alkylene
diamines, such N,N,N1 N,1 -tetraacetylethylene diamine (TAED) and N,N,N1 ,N1 -
tetraacetylmethylene diamine (TAMD); acylated glycolurils, such as
tetraacetylgylcoluril (TAGU); triacetyl cyanurate and sodium sulphophenyl ethyl
carbonic acid ester.
Peroxygen bleaching agents are also well known in the art, for example, peracids
(e.g., PAP), perborates, percarbonates, peroxyhydrates, and mixtures thereof.
Specific preferred examples include: sodium perborate, commercially available in
the form of mono- and tetra-hydrates, and sodium carbonate peroxyhydrate.
Other examples of peroxyl species and activators as well as other transition metal
catalyst are found in WO 02/0771 45.
It is also preferred to include in the compositions, a stabiliser for the bleach or
bleach system, for example ethylene diamine tetramethylene phosphonate and
diethylene triamine pentamethylene phosphonate or other appropriate organic
phosphonate or salt thereof. These stabilisers can be used in acid or salt form
which is the calcium, magnesium, zinc or aluminium salt form. The stabiliser may
be present at a level of up to about 1 wt%, preferably from about 0.1 % to about
0.5 wt%.
Since many bleaches and bleach systems are unstable in aqueous liquid
detergents and/or interact unfavourably with other components in the composition,
e.g. enzymes, they may for example be protected, e.g. by encapsulation or by
formulating a structured liquid composition, whereby they are suspended in solid
form.
Photobleaches, including singlet oxygen photobleaches, could also be used.
PREMIX B
In addition to any viscosity modifying ingredient, normally water, but hydrotropes
could also be used, Premix B comprises the microcapsules.
Microcapsules
An essential element of the composition as made by the process according to the
invention is at least 0.01 wt% of microcapsules, with an anionic charge. Such
microcapsules may deliver a variety of benefit agents by deposition onto
substrates such as laundry fabric. To obtain maximum benefit they should be well
dispersed through the liquid detergent composition and the vast majority of the
microcapsules must not be significantly agglomerated. It is our finding that any
microcapsules that become agglomerated during the processing remain so in the
container and will thus be dispensed unevenly during use of the composition.
This is highly undesirable. The contents of the microcapsules are normally liquid.
For example, fragrances, oils, fabric softening additives and fabric care additives
are possible contents. The invention is not specific for any particular type of
content. Preferred microcapsules are particles termed core-in-shell
microcapsules. As used herein, the term core-in-shell microcapsules refers to
encapsulates whereby a shell which is substantially or totally water-insoluble at
40°C surrounds a core which comprises or consists of a benefit agent (which is
either liquid or dispersed in a liquid carrier).
Suitable microcapsules are those described in US-A-5 066 4 19 which have a
friable coating, preferably an aminoplast polymer. Preferably, the coating is the
reaction product of an amine selected from urea and melamine, or mixtures
thereof, and an aldehyde selected from formaldehyde, acetaldehyde,
glutaraldehyde or mixtures thereof. Preferably, the coating is from 1 to 30 wt% of
the particles.
Core-in-shell microcapsules of other kinds are also suitable for use in the present
invention. Ways of making such other microcapsules of benefit agents such as
perfume include precipitation and deposition of polymers at the interface such as
in coacervates, as disclosed in GB-A-751 600, US-A-3 341 466 and EP-A-385
534, as well as other polymerisation routes such as interfacial condensation, as
described in US-A-3 577 5 15, US-A-2003/01 25222, US-A-6 020 066 and WO-A-
03/101 606. Microcapsules having polyurea walls are disclosed in US-A-6 797
670 and US-A-6 586 107.
Other patent applications specifically relating to use of melamine-formaldehyde
core-in-shell microcapsules in aqueous liquids are WO-A-98/28396,
WO02/074430, EP-A-1 244 768, US-A-2004/0071 746 and US-A-2004/01 42868.
White oil is a highly refined, colourless hydrocarbon oil of low volatility and a wide
range of viscosities; used for lubrication of food and textile machinery and as
medicinal and mineral oils. Melamine shelled microcapsules containing white oil
are slightly anionic (negatively charged). Surface charge on the microcapsules
has been found to affect their dispersal. A low charge seems to result in there
being too little electrostatic repulsion/ stabilisation to keep them apart in low water
(concentrated) formulations. This gets even worse for highly concentrated anionic
compositions. The problem seems to be worse for weakly anionic particles of
certain size.
Perfume encapsulates are a preferred type of microcapsule suitable for use in the
present invention.
The preferred perfume microcapsules utilised in the present invention are core-inshell
microcapsules. As used herein, the term core-in-shell microcapsules refers
to encapsulates whereby a shell which is substantially or totally water-insoluble at
40°C surrounds a core which comprises or consists of perfume (including any
liquid carrier therefor).
A preferred class of core-in-shell perfume microcapsule comprises those
disclosed in WO 2006/066654 A 1. These comprise a core having from about 5%
to about 50 wt% of perfume dispersed in from about 95% to about 50wt% of a
carrier material. This carrier material preferably is a non-polymeric solid fatty
alcohol or fatty ester carrier material, or mixtures thereof. Preferably, the esters or
alcohols have a molecular weight of from about 100 to about 500 and a melting
point from about 37°C to about 80°C, and are substantially water-insoluble. The
core comprising the perfume and the carrier material are coated in a substantially
water-insoluble coating on their outer surfaces. Similar microcapsules are
disclosed in US 5,1 54,842 and these are also suitable.
The microcapsules as described in US-A-5 066 4 19 have a friable coating which
is preferably an aminoplast polymer. Preferably, the coating is the reaction
product of an amine selected from urea and melamine, or mixtures thereof, and
an aldehyde selected from formaldehyde, acetaldehyde, glutaraldehyde or
mixtures thereof. Preferably, the coating is from 1 to 30 wt% of the particles.
Core-in-shell perfume microcapsules of other kinds are also suitable for use in the
present invention. Ways of making such other microcapsules of perfume include
precipitation and deposition of polymers at the interface such as in coacervates,
as disclosed in GB-A-751 600, US-A-3 341 466 and EP-A-385 534, as well as
other polymerisation routes such as interfacial condensation, as described in USA-
3 577 5 15, US-A-2003/01 25222, US-A-6 020 066 and WO-A-03/1 0 1606.
Microcapsules having polyurea walls are disclosed in US-A-6 797 670 and US-A-6
586 107.
Other patent applications specifically relating to use of melamine-formaldehyde
core-in-shell microcapsules in aqueous liquids are WO-A-98/28396,
WO02/074430, EP-A-1 244 768, US-A-2004/0071 746 and US-A-2004/01 42868.
The microcapsules may attach to suitable substrates, e.g. to provide persistent
fragrance that is desirably released after the cleaning process is complete.
Liquid detergent compositions
The process provides structured liquid detergent compositions, wherein the
microcapsules are present without a significant proportion of them being in
wasteful and size enlarged agglomerated form. The composition is concentrated
and has greater than or equal to 30 wt% of surfactant and an external structuring
system, preferably hydrogenated castor oil, is present at a concentration of from
0.15 and 0.5 wt% of the total composition.
Preferably, the concentration of surfactants in the liquid detergent composition
according to the invention is from 30 to 65 wt%, more preferred from 32 to 60
wt%, and most preferably from 35 to 50 wt% of the total composition.
The liquid cleaning composition may be formulated as a concentrated cleaning
liquid for direct application to a substrate, or for application to a substrate following
dilution, such as dilution before or during use of the liquid composition by the
consumer or in washing apparatus.
Whilst the composition and method according to the present invention may be
used for cleaning any suitable substrate, the preferred substrate is a laundry
fabric. Cleaning may be carried out by simply leaving the substrate in contact for
a sufficient period of time with a liquid medium constituted by or prepared from the
liquid cleaning composition. Preferably, however, the cleaning medium on or
containing the substrate is agitated.
Product Form
The liquid detergent compositions obtainable by the method according to the
present invention are preferably concentrated liquid cleaning compositions. The
liquid compositions have a physical form, which ranges from a pourable liquid, a
pourable gel to a non-pourable gel. These forms are conveniently characterised
by the product viscosity. In these definitions, and unless indicated explicitly to the
contrary, throughout this specification, all stated viscosities are those measured at
a shear rate of 2 1 s-1 and at a temperature of 25°C. This shear rate is the shear
rate that is usually exerted on the liquid when poured from a bottle. The liquid
detergent compositions made according to the invention are shear-thinning
liquids.
Pourable liquid detergent compositions preferably have a viscosity of not more
than 1,500 mPa.s, more preferably not more than 1,000 mPa.s, still more
preferably, not more than 500 mPa.s. Typically, the viscosity is lower than 500
mPa.s at 2 1 s-1 .
Liquid detergent compositions, which are pourable gels, preferably have a
viscosity of at least 1,500 mPa.s but no more than 6,000 mPa.s, more preferably
no more than 4,000 mPa.s, still more preferably no more than 3,000 mPa.s and
especially no more than 2,000 mPa.s.
Non-pourable gels, preferably have a viscosity of at least 6,000 mPa.s but no
more than 12,000 mPa.s, more preferably no more than 10,000 mPa.s, still more
preferably no more than 8,000 mPa.s and especially not more than 7,000 mPa.s.
For the purpose of the invention a composition is considered physically stable
when it remains homogeneous with dispersed and suspended perfume
encapsulates over a period of about 3 months at temperatures from 5 to 50°C.
The invention will now be further described with reference to the following nonlimiting
examples
Example 1
The composition as listed in Table 1 (PREMIX A) was prepared by a process as
described in PCT/EP2009/062313, the relevant content of which is repeated
above. This process is based on a conventional neutralisation process for
manufacture of a LAS/SLES/NI and soap based active heavy-duty liquid
detergent. The enzymes and perfume are added after the neutralisation.
Table 1 - PREMIX A
The liquid detergent composition was obtained by the following method:
Premix 1
Under agitation at 150 rpm, using an overhead stirrer, 200g of deionised water
was added to a 3 litre beaker and warmed to 30°C. Optical Brightener 1.47g was
then added to this solution along with glycerol 50g, propylene glycol 90g and the
neutralising bases sodium hydroxide 57.5g and thethanolamine 3 1.5g. Then
Nonionic 7EO, 201 g, linear alkylbenzene sulphonic acid, 128g, and citric acid 20g
were added in quick succession generating considerable heat of neutralisation
and bringing the temperature to 65-70°C. This base temperature of 65-70°C was
maintained until addition of the Premix 2 .
Premix 2
Prifac 5908, 47g, was dissolved in a separate 500ml beaker using agitation at 100
rpm and heating to 70-75°C. Then 2g of hydrogenated castor oil, Thixcin ® ex
Elementis was dissolved in the hot fatty acid. This premix is stirred for a further 5-
10 minutes to ensure complete dissolution and mixing of the external structurant.
The dissolution is complete when the premix 2 solution is completely transparent.
PREMIX A: (Premix 1 + Premix 2)
The two premixes are now combined by adding Premix 2 (70-75°C) to Premix 1
(65-70°C), increasing the agitation to 200rpm and allowing the two premixes to
mix thoroughly for 10 minutes. Then the sequestrant,1 6g was added followed by
sodium laurylether sulphate (sLES) 96g and allowed to mix for a further 10
minutes before cooling to 30°C. Cooling was done by either natural cooling over
a period of 2 hours, or alternatively the main batch was cooled using a plate heat
exchanger cooling the main mix from 60-65°C to 30°C in less than a minute and
keeping it for 10 minutes at this low temperature.
Subsequently, colour dyes 0.08g were added, as well as enzymes 10.5g, and
perfume 10g and allowed to mix for a further 10 minutes before pumping out of
the vessel to form PREMIX A. This mix is a non-Newtonian fluid with a yield
stress of ca. 0.3 Pa and a viscosity of 350 mPas at 2 1 s-1 .
PREMIX B
The microcapsules used had a melamine formaldehyde shell, were anionic with
an average particle size of 15.8 microns. They are available in a slurry with a
solids content of 46.8 wt% and a slurry viscosity of 425 mPas. On dilution with an
equivalent volume of water the resulting PREMIX B has a viscosity at 25°C of 10
mPas.
2 parts of PREMIX B were added to 98 parts of PREMIX A in a paddle stirred
batch mixer and mixed for approx 15 mins, using the vessel agitation only. This
resulted in formation of agglomerates of microcapsules, the agglomerated were
well dispersed in the mixture.
To try to break-up the agglomerates, the mixture was then pumped through an in
line static mixer. The typical mixing energy supplied by such a mixer is about 100
times that of a paddle mixer.
When mixed in to a liquid in the conventional way using such a paddle mixer
these microcapsules produce a dispersion ratio of 70:30 (nonagglomerated
:agglomerated as defined above) compared to 96:4 using the
process according to the present invention.
The microcapsule level on the final dispersed mix is 0.46%.
Microscopic visual inspection of the dispersed microcapsules also proved that
there was no rupture of the microcapsules caused by the process.

Claims

1. A process for the incorporation of microcapsules with anionic charge into a
structured aqueous concentrated liquid detergent comprising at least 30 wt%,
preferably at most 65 wt%, total surfactant of which at least 5 wt% based on the
total composition is anionic surfactant, including soap, and an external structurant,
the process comprising the combining of two premixes; Premix A which is the
structured aqueous concentrated liquid detergent composition without
microcapsules and Premix B which comprises an aqueous dispersion of the
microcapsules with anionic charge, characterised in that:
Premix B is a slurry of microcapsules with a maximum viscosity at 25°C of 100
mPas and at least 90 wt% of the microcapsules having a particle size in the range
5 to 30 microns, and that
Premix B is added to Premix A and the resulting combined mixture is passed
through a static in-line mixer with an energy input of from 20 to 500 J/kg to form,
immediately after the mixer, a structured liquid comprising less than 10%, based
on the total number of groups of microcapsules, agglomerated groups of
microcapsules, an agglomerated group of microcapsules being defined as a group
having more than 5 microcapsules grouped together.
2 . A process according to claim 1 in which the viscosity of Premix B is
reduced by dilution with water.
3 . A process according to any preceding claim in which the external
structurant is hydrogenated castor oil (castor wax).
4 . A process according to any preceding claim in which the microcapsules
comprise a melamine formaldehyde shell.
5 . A process according to any one of claims 1 to 3 in which the microcapsules
comprise a shell comprises a material selected from (poly)urea, (poly)urethane,
starch/ polysaccharide and aminoplasts.
6 . A process according to any preceding claim in which the microcapsules are
perfume encapsulates.