U.S. patent application number 10/297515 was filed with the patent office on 2003-08-21 for method for producing nanoparticles suspensions.
Invention is credited to Dolhaine, Hans, Schroeder, Christine, Stalberg, Theo.
Application Number | 20030155668 10/297515 |
Document ID | / |
Family ID | 7644843 |
Filed Date | 2003-08-21 |
United States Patent
Application |
20030155668 |
Kind Code |
A1 |
Stalberg, Theo ; et
al. |
August 21, 2003 |
Method for producing nanoparticles suspensions
Abstract
The invention relates to a method for producing a suspension of
an undecomposed meltable material having an average particle
diameter of between 5 to 500 nm. The inventive method enables
stable suspensions to be produced and is characterised in that it
only requires a simple technical infrastructure in many production
plants, it delivers high space-time yields, and can easily be
scaled up.
Inventors: |
Stalberg, Theo; (Monheim,
DE) ; Schroeder, Christine; (Duesseldorf, DE)
; Dolhaine, Hans; (Korschenbroich, DE) |
Correspondence
Address: |
HENKEL CORPORATION
2500 RENAISSANCE BLVD
STE 200
GULPH MILLS
PA
19406
US
|
Family ID: |
7644843 |
Appl. No.: |
10/297515 |
Filed: |
April 15, 2003 |
PCT Filed: |
May 29, 2001 |
PCT NO: |
PCT/EP01/06077 |
Current U.S.
Class: |
264/4 |
Current CPC
Class: |
A61K 8/044 20130101;
C09K 23/14 20220101; A61K 2800/413 20130101; B82Y 5/00 20130101;
C09K 23/54 20220101; A61K 8/416 20130101; A61Q 19/00 20130101; C09K
23/00 20220101; A61K 8/342 20130101 |
Class at
Publication: |
264/4 |
International
Class: |
B65B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2000 |
DE |
100279481 |
Claims
1. A process for the production of a suspension of a substance
which can be melted without decomposing with a mean particle
diameter in the range from 5 to 500 nm, characterized in that (a)
an emulsion is prepared from the substance which can be melted
without decomposing, a liquid phase in which the substance is
poorly soluble and an effective quantity of at least one surface
modifier and (b) the resulting emulsion is expanded into a zone of
reduced pressure so that the emulsion is cooled to below the
melting point of the substance.
2. A process as claimed in claim 1, characterized in that the mean
particle diameter is in the range from 10 to 300 nm.
3. A process as claimed in claim 1 or 2, characterized in that the
emulsion from step (a) is prepared by melting the substance
together with the liquid phase and the at least one surface
modifier.
4. A process as claimed in claim 1 or 2, characterized in that the
emulsion from step (a) is prepared by initially introducing the
molten substance and then adding the liquid phase and at least one
surface modifier either together or successively.
5. A process as claimed in any of claims 1 to 4, characterized in
that the cooling of the emulsion to below the melting point of the
substance in step (c) is effected by partial evaporation of the
liquid phase.
6. A process as claimed in any of claims 1 to 5, characterized in
that the pressure in step (b) is in the range from 10 to 800 mbar
and preferably in the range from 20 to 300 mbar.
7. A process as claimed in any of claims 1 to 6, characterized in
that 5 to 50% by weight and preferably 10 to 20% by weight of the
liquid phase is removed from the emulsion in step (b), based on the
total weight of the emulsion before expansion.
Description
[0001] This invention relates to a process for the production of a
suspension of a substance which can be melted without decomposing
with a mean particle diameter in the range from 5 to 500 nm.
[0002] Many potential uses in various fields have fairly recently
been found for suspensions of substances with a particularly small
particle size, more particularly with a particle size below 1
micrometer. Various processes are known from the literature for the
production of fine-particle suspensions. Where the substances are
fusible, processes in which a melt of the substances is emulsified
and then cooled have proved successful.
[0003] Thus, EP-B1 0 506 197 describes a process for the production
of aqueous dispersions of lipid nanoparticles in which the lipid is
first melted in an aqueous phase, optionally in the presence of
emulsifiers. The mixture of molten lipid and aqueous phase is then
dispersed by intensive mixing, the lipid being converted in the
process into nanoparticlulate droplets with a size in the range
from 50 to 1,000 nm which are solidified by cooling to form the
dispersion according to the invention. This process requires very
intensive mixing to obtain the droplets in the nanometer range.
According to the Examples, mixing with a Turrax homogenizer is not
enough and a stable suspension with a particle size in the
nanometer range can only be obtained by the additional use of a
high-pressure homogenizer of the microfluidizer type.
[0004] The processes known from the prior art for the production of
nanoparticle suspensions of fusible substances do not
simultaneously satisfy the need for
[0005] a) simple and inexpensive workability, even on an industrial
scale, by which is meant in particular a process involving little
outlay on equipment which comprises only a few steps and still
gives a high volume/time yield,
[0006] b) high storage stability of the suspensions produced
and
[0007] c) the possibility of producing even concentrated
suspensions.
[0008] The problem addressed by the present invention was to remedy
the deficiencies of the prior art and to provide a production
process which would satisfy the requirements mentioned above.
[0009] The problem stated above has been solved by the provision of
a process for the production of a suspension of a substance which
can be melted without decomposing with a mean particle diameter in
the range from 5 to 500 nm, characterized in that
[0010] (a) an emulsion is prepared from the substance which can be
melted without decomposing, a liquid phase in which the substance
is poorly soluble and an effective quantity of at least one surface
modifier and
[0011] (b) the resulting emulsion is expanded into a zone of
reduced pressure so that the emulsion is cooled to below the
melting point of the substance.
[0012] In a preferred embodiment of the invention, the mean
particle diameter of the substance which can be melted without
decomposing in the suspension is in the range from 10 to 300 nm and
more particularly in the range from 20 to 100 nm.
[0013] The particle diameters mentioned are meant to be interpreted
as the diameter in the direction of the largest linear dimension of
the particles. In the production of the fine particles, particles
with a size which follows a distribution curve are always obtained.
The particle size may be experimentally determined, for example, by
the dynamic light scattering method known to the expert.
[0014] Substances which can be melted without decomposing are
understood to be substances which have a melting point or melting
range of 25.degree. to 300.degree. C., preferably 30.degree. to
150.degree. C. and more particularly 35.degree. C. to 100.degree.
C. Suitable substances are both individual chemicals and
mixtures.
[0015] According to the invention, preferred substances are organic
substances and, more particularly, organic substances poorly
soluble in water.
[0016] The substances suitable for use in accordance with the
invention are, for example, substances which are industrially used
in the cosmetic and pharmaceutical preparations, in foods, in
detergents/cleaners, in adhesives, in surface treatment, in hygiene
products and in agriculture. Preferred substances are the
substances used in cosmetic preparations such as, for example, UV
protection factors, dyes, perfumes, emulsifiers, waxes, lipid layer
enhancers, antioxidants, deodorants and antiperspirants. Other
preferred substances are pharmacologically active substances which
are used as active principles in cosmetic, dermatological and
pharmaceutical preparations.
[0017] According to the invention, the liquid phase may be
selected, for example, from
[0018] water,
[0019] lower aliphatic alcohols, for example those containing 1 to
4 carbon atoms, such as methanol, ethanol, isopropyl alcohol and
the isomeric butanols,
[0020] polyols preferably containing 2 to 15 carbon atoms and at
least two hydroxyl groups such as, for example, ethylene glycol,
diethylene glycol, propylene glycol, butylene glycol, hexylene
glycol, polyethylene glycols with an average molecular weight of
100 to 1,000 dalton, glycerol, technical oligoglycerol mixtures
with a degree of self-condensation of 1.5 to 10 such as, for
example, technical diglycerol mixtures with a diglycerol content of
40 to 50% by weight,
[0021] lower alkyl glucosides, more particularly those containing 1
to 8 carbon atoms in the alkyl group such as, for example, methyl
and butyl glucoside
[0022] and mixtures of the above-mentioned substances. Water is the
preferred liquid phase.
[0023] By poor solubility is meant that at most 1% by weight,
preferably at most 0.1% by weight and more particularly at most
0.01% by weight of the substance which can be melted without
decomposing dissolves in the liquid phase at 20.degree. C., based
on the total weight of the solution.
[0024] Basically, the ratio by weight between the substance which
can be melted without decomposing and the liquid phase is not
critical and is largely determined by the need for the substance to
be sufficiently well distributed in the liquid phase.
[0025] Surface modifiers in the context of the invention are
substances which physically adhere to, but preferably do not
chemically react with, the surface of the nanoparticles. The
individual molecules of the surface modifiers adsorbed onto the
surface are substantially free from intermolecular bonds. By
surface modifiers are meant above all dispersants. Dispersants are
also known to the expert by such terms as, for example,
emulsifiers, protective colloids, wetting agents and
detergents.
[0026] Suitable surface modifiers are, for example, emulsifiers of
the nonionic surfactant type from at least one of the following
groups:
[0027] (1) adducts of 2 to 30 mol ethylene oxide and/or 0 to 5 mol
propylene oxide with linear fatty alcohols containing 8 to 22
carbon atoms, with fatty acids containing 12 to 22 carbon atoms and
with alkylphenols containing 8 to 15 carbon atoms in the alkyl
group;
[0028] (2) C.sub.12/18 fatty acid monoesters and diesters of
addition products of 1 to 30 mol ethylene oxide onto glycerol;
[0029] (3) glycerol monoesters and diesters and sorbitan monoesters
and diesters of saturated and unsaturated fatty acids containing 6
to 22 carbon atoms and ethylene oxide addition products
thereof;
[0030] (4) alkyl mono- and oligoglycosides containing 8 to 22
carbon atoms in the alkyl group and ethoxylated analogs
thereof;
[0031] (5) addition products of 2 to 60 mol ethylene oxide onto
castor oil and/or hydrogenated castor oil;
[0032] (6) polyol esters and, in particular, polyglycerol esters
such as, for example, polyglycerol polyricinoleate, polyglycerol
poly-12-hydroxystearate or polyglycerol dimerate. Mixtures of
compounds from several of these classes are also suitable;
[0033] (7) partial esters based on linear, branched, unsaturated or
saturated C.sub.6/22 fatty acids, ricinoleic acid and
12-hydroxystearic acid and glycerol, polyglycerol, pentaerythritol,
dipentaerythritol, sugar alcohols (for example sorbitol), alkyl
glucosides (for example methyl glucoside, butyl glucoside, lauryl
glucoside) and polyglucosides (for example cellulose);
[0034] (8) mono-, di- and trialkyl phosphates and mono-, di- and/or
tri-PEG-alkyl phosphates and salts thereof;
[0035] (9) wool wax alcohols;
[0036] (10) polysiloxane/polyalkyl polyether copolymers and
corresponding derivatives;
[0037] (11) mixed esters of pentaerythritol, fatty acids, citric
acid and fatty alcohol according to DE-PS 1165574 and/or mixed
esters of fatty acids containing 6 to 22 carbon atoms, methyl
glucose and polyols, preferably glycerol or polyglycerol, and
[0038] (12) polyalkylene glycols.
[0039] The addition products of ethylene oxide and/or propylene
oxide onto fatty alcohols, fatty acids, alkylphenols, glycerol
monoesters and diesters and sorbitan monoesters and diesters of
fatty acids or onto castor oil are known commercially available
products. They are homolog mixtures of which the average degree of
alkoxylation corresponds to the ratio between the quantities of
ethylene oxide and/or propylene oxide and substrate with which the
addition reaction is carried out.
[0040] C.sub.8/18 alkyl mono- and oligoglycosides, their production
and their use are known from the prior art. They are produced in
particular by reacting glucose or oligosaccharides with primary
alcohols containing 8 to 18 carbon atoms. So far as the glycoside
component is concerned, both monoglycosides where a cyclic sugar
unit is attached to the fatty alcohol by a glycoside bond and
oligomeric glycosides with a degree of oligomerization of
preferably up to about 8 are suitable. The degree of
oligomerization is a statistical mean value on which a homolog
distribution typical of such technical products is based.
[0041] Typical examples of anionic emulsifiers are soaps,
alkylbenzenesulfonates, alkanesulfonates, olefin sulfonates,
alkylether sulfonates, glycerol ether sulfonates, .alpha.-methyl
ester sulfonates, sulfofatty acids, alkyl sulfates, alkylether
sulfates such as, for example, fatty alcohol ether sulfates,
glycerol ether sulfates, hydroxy mixed ether sulfates,
monoglyceride (ether) sulfates, fatty acid amide (ether) sulfates,
mono- and dialkyl sulfosuccinates, mono- and dialkyl
sulfosuccinamates, sulfotriglycerides, amide soaps, ether
carboxylic acids and salts thereof, fatty acid isethionates, fatty
acid sarcosinates, fatty acid taurides, N-acylamino acids such as,
for example, acyl glutamates and acyl aspartates, alkyl
oligoglucoside sulfates, protein fatty acid condensates
(particularly wheat-based vegetable products) and alkyl (ether)
phosphates. If the anionic surfactants contain polyglycol ether
chains, they may have a conventional homolog distribution although
they preferably have a narrow homolog distribution.
[0042] In addition, zwitterionic surfactants may be used as
emulsifiers. Zwitterionic surfactants are surface-active compounds
which contain at least one quaternary ammonium group and at least
one carboxylate and one sulfonate group in the molecule.
Particularly suitable zwitterionic surfactants are the so-called
betaines, such as the N-alkyl-N, N-dimethyl ammonium. glycinates,
for example cocoalkyl dimethyl ammonium glycinate,
N-acylaminopropyl-N, N-dimethyl ammonium glycinates, for example
cocoacylaminopropyl dimethyl ammonium glycinate, and
2-alkyl-3-carboxymethyl-3-hydroxyethyl imidazolines containing 8 to
18 carbon atoms in the alkyl or acyl group and cocoacylaminoethyl
hydroxyethyl carboxymethyl glycinate. The fatty acid amide
derivative known under the CTFA name of Cocoamidopropyl Betaine is
particularly preferred. Ampholytic surfactants are also suitable
emulsifiers. Ampholytic surfactants are surface-active compounds
which, in addition to a C.sub.8/18 alkyl or acyl group, contain at
least one free amino group and at least one --COOH-- or
--SO.sub.3H-- group in the molecule and which are capable of
forming inner salts. Examples of suitable ampholytic surfactants
are N-alkyl glycines, N-alkyl propionic acids, N-alkylaminobutyric
acids, N-alkyliminodipropionic acids,
N-hydroxyethyl-N-alkylamidopropyl glycines, N-alkyl taurines,
N-alkyl sarcosines, 2-alkylaminopropionic acids and
alkylaminoacetic acids containing around 8 to 18 carbon atoms in
the alkyl group. Particularly preferred ampholytic surfactants are
N-cocoalkylaminopropionate, cocoacylaminoethyl aminopropionate and
C.sub.2/18 acyl sarcosine. Besides ampholytic emulsifiers,
quaternary emulsifiers may also be used, those of the esterquat
type, preferably methyl-quaternized difatty acid triethanolamine
ester salts, being particularly preferred.
[0043] Protective colloids suitable as surface modifiers are, for
example, natural water-soluble polymers such as, for example,
gelatin, casein, gum arabic, lysalbinic acid, starch, albumin,
alginic acid and alkali metal and alkaline earth metal salts
thereof, water-soluble derivatives of water-insoluble natural
polymers such as, for example, cellulose ethers, such as methyl
cellulose, hydroxyethyl cellulose, carboxymethyl cellulose or
modified carboxymethyl cellulose, hydroxyethyl starch or
hydroxypropyl guar, and synthetic water-soluble polymers such as,
for example, polyvinyl alcohol, polyvinyl pyrrolidone, polyalkylene
glycols, polyaspartic acid and poylacrylates.
[0044] According to the invention, preferred surface modifiers are
nonionic or anionic surfactants and mixtures thereof. Among the
nonionic surfactants, products of the addition of 2 to 60 mol
ethylene oxide onto castor oil and/or hydrogenated castor oil,
alkyl mono- and oligoglycosides containing 8 to 22 carbon atoms in
the alkyl group and polyalkylene glycols are particularly
preferred.
[0045] In the context of the invention, an effective quantity of
the at least one surface modifier is the minimum quantity necessary
for obtaining a stable suspension of the substance which can be
melted without decomposing in the practical application of the
process according to the invention. The necessary quantity can be
determined by simple routine tests. The substance which can be
melted without decomposing and the at least one surface modifier
are generally used in a ratio by weight of 1:10 to 10:1 and
preferably in a ratio by weight of 1:2 to 2:1.
[0046] In step (a) of the process according to the invention, an
emulsion is prepared from the substance which can be melted without
decomposing, a liquid phase in which the substance is poorly
soluble and an effective quantity of at least one surface modifier.
The substance which can be melted without decomposing is present in
this emulsion in liquid, i.e. molten, form. Accordingly, the
emulsion is prepared at a temperature above the melting point of
the substance which can be melted without decomposing. A
temperature 5 to 25.degree. C. above the melting point of the
substance which can be melted without decomposing is particularly
preferred, a temperature 10 to 20.degree. C. above that temperature
being most particularly preferred.
[0047] If the mixture of the substance which can be melted without
decomposing used in accordance with the invention and surface
modifier shows a reduction in melting point, the above figures
apply to the melting point of the mixture rather than the substance
which can be melted without decomposing alone.
[0048] The preparation of the emulsion in step (a) of the process
according to the invention can be carried out in various ways. In
one variant, the substance which can be melted without decomposing
is first introduced into the liquid phase and the mixture is then
heated beyond the melting point of the substance to form a
two-phase system. The molten substance is then emulsified by
addition of one or more surface modifiers. In another variant of
the process, the substance and the liquid phase are introduced
together with the surface modifier(s) and then melted and
emulsified together or the melt of substance and surface
modifier(s) initially prepared is mixed with the liquid phase which
may also contain one or more surface modifiers. In the latter case,
the temperature of the liquid phase should be selected so that it
is above the melting point of the mixture of substance and surface
modifier(s). In yet another variant of the process, the melt of the
substance may be mixed and emulsified with a solution of one or
more surface modifiers in the liquid phase, the temperature of the
solution having to be selected so that it is above the melting
point of the substance.
[0049] In a preferred variant of step (a) of the process according
to the invention, the emulsion is prepared by melting the substance
which can be melted without decomposing together with the liquid
phase and the at least one surface modifier.
[0050] In another preferred variant of step (a) of the process
according to the invention, the emulsion is prepared by first
introducing the molten substance and then adding the liquid phase
and at least one surface modifier together or successively at a
temperature above the melting point of the substance. In the latter
case, the liquid phase may be added before or after the surface
modifier.
[0051] To prepare the emulsion in step (a) of the process according
to the invention, the components are mixed preferably exclusively
with a stirrer of the type typically used for industrial
stirred-tank reactors, for example a blade, propeller or impeller
stirrer.
[0052] The emulsion prepared in step (a) of the process according
to the invention is then expanded in the second step of the process
into a zone of reduced pressure so that the emulsion is cooled to
below the melting point of the substance. Where the mixture of the
substance and the surface modifier(s) present in the emulsion has a
lower melting point than the substance itself, the emulsion must be
cooled to below the melting point of the mixture.
[0053] The introduction of the emulsion into the reduced pressure
zone in step (b) of the process is carried out by effecting the
cooling of the emulsion to below the melting point of the substance
by partial evaporation of the liquid phase. The cooling process
takes place in a very short time of preferably 0.01 to 5 seconds
and more particularly 0.1 to 2 seconds.
[0054] The vacuum is selected so that the emulsified particles of
the substance which can be melted without decomposing solidify
during the expansion by evaporation cooling. Accordingly, the
choice of a suitable vacuum is determined by the nature of the
liquid phase and the melting point of the substance or the mixture
of the substance and the surface modifier(s) and may readily be
made by the expert, for example on the basis of the vapor pressure
curves of the liquid phase. Where water is used as the liquid
phase, a suitable vacuum is one in the range from 10 to 800 mbar.
Here, cooling to ca. 60.degree. C. is achieved, for example, at 200
mbar and cooling to ca. 20.degree. C. at 20 mbar.
[0055] According to the invention, therefore, a pressure of 10 to
800 mbar is preferred for step (b), a pressure of 20 to 300 mbar
being particularly preferred.
[0056] In one embodiment of the invention, the emulsion is expanded
into the vacuum through a line equipped with a valve.
Alternatively, expansion through a nozzle is also possible.
[0057] Surprisingly, the process according to the invention gives
nanoparticle suspensions with mean particle diameters in the range
from 5 to 500 nm without the emulsion prepared in step (a) of the
process itself having to have this particle fineness.
[0058] According to the teaching of the prior art, as represented
for example by EP-B 0 506 197 cited at the beginning, particles of
the required size have to be produced in the emulsion initially
prepared which can only be done by introducing high mechanical
energy, for example through a high-pressure homogenizer. These
particles then solidify on cooling without the particle size
changing, more particularly becoming smaller. On the contrary, it
is repeatedly pointed out in the literature that the cooling of
nanoparticle emulsions of molten substances is often accompanied by
agglomeration into relatively coarse particles.
[0059] By contrast, it has been found in accordance with the
invention that the additional use of a high-pressure homogenizer in
step (a) of the process according to the invention actually leads
to a deterioration, i.e. to the formation of distinctly coarser
particles.
[0060] Accordingly, in the process according to the invention, the
particles of the emulsified substance are reduced in size and, at
the same time, solidified to form a nanoparticle suspension by the
procedure adopted in step (b). It is assumed that this is
attributable to the mechanical influences occurring during
expansion into the vacuum in conjunction with the sudden cooling
which convert the emulsion into a suspension in fractions of a
second.
[0061] The process according to the invention gives nanoparticle
suspensions which show particularly high stability in storage, i.e.
neither agglomerate nor sediment, even under heat stress.
[0062] The production process according to the invention is
distinguished by the fact that it requires only a simple technical
infrastructure available in many production plants, gives high
volume/time yields, is inexpensive and can readily be
scaled-up.
[0063] Another advantage of the process according to the invention
is that the suspension is concentrated by the partial evaporation
of the liquid phase in step (b).
[0064] Accordingly, the present invention also relates to a process
as described in the foregoing in which 5 to 50% by weight and
preferably 10 to 20% by weight of the liquid phase is removed from
the emulsion in step (b), based on the total weight of the emulsion
before expansion.
[0065] This concentration is advantageous in cases where, although
a certain quantity of the liquid phase is necessary for forming the
emulsion in the first step of the process, this liquid phase is
problematical so far as the subsequent use of the nanoparticle
suspension is concerned. Thus, where the nanoparticle suspensions
are used, for example, in cosmetic or pharmaceutical preparations,
it is generally desirable for various reasons, for example to avoid
formulation problems or unwanted impurities, to introduce as few
accompanying substances as possible--including the liquid phase of
a nanoparticle suspension--into the formulation with the
nanoparticles.
[0066] If desired, the nanoparticle suspensions produced in
accordance with the invention can be completely freed from the
liquid phase by methods known per se, preferably by evaporating the
liquid phase under reduced pressure at temperatures below the
melting point of the nanoparticles.
[0067] The nanoparticles are thus obtained in the form of flowable
dry powders which can readily be redispersed, even after prolonged
storage, and which are suitable for use, for example, in cosmetic
and pharmaceutical preparations, in foods, in detergents/cleaners,
in adhesives, in hygiene products and in agriculture.
[0068] The following Examples are intended to illustrate the
invention.
EXAMPLES
Example 1
Preparation of a Suspension of Dehyquart F 75
[0069] 6.0 kg Dehyquart F 75 (Distearoylethyl Hydroxyethylmonium
Methosulfate and Cetearyl Alcohol), 6.0 kg Eumulgin B2
(polyoxyethylene-20-ceylstearyl alcohol) and 32.2 kg dist. water
were introduced into a reactor and heated to 60.degree. C. The
mixture was then heated with stirring to 90-95.degree. C. and
stirred at that temperature for half an hour. The emulsion formed
was expanded through a nozzle over a period of 15 minutes into a
second reactor kept by evacuation at a pressure of 20 to 30 mbar.
During the expansion, the dispersion was cooled from 90-95.degree.
C. to 20-25.degree. C. 36.0 kg of a storable suspension with a mean
particle size of 30 nm were obtained.
Example 2
Preparation of a Suspension of Dehyquart AU 56
[0070] 28.0 kg of suspension with a mean particle size of 60 nm
were obtained as in Example 1 from 6.0 kg Dehyquart AU 56 (N-methyl
triethanolammonium dialkylester methosulfate with 10% by weight
isopropanol), 6.0 kg Plantacare 1200 UP (C.sub.12-16 alkyl
glycoside) and 19.8 kg dist. water.
Example 3
Preparation of a Suspension of Lanette O
[0071] 3.0 kg Lanette O (cetylstearyl alcohol), 3.0 kg Texapon N 70
(sodium lauryl ether sulfate+2 EO) and 15.6 kg dist. water were
reacted as in Example 1, another 12.0 kg water having been
introduced into the reactor into which the emulsion was expanded.
30.5 kg of suspension with a mean particle size of 200 nm were
obtained.
Example 4
Preparation of a Suspension of Lanette O
[0072] 32.0 kg of suspension with a mean particle size of 200 nm
were obtained as in Example 1 from 3.0 kg Lanette O, 3.0 kg
Eumulgin HRE 455 (hydrogenated castor oil+40 EO in propylene
glycol/water) and 33.1 kg dist. water.
Comparison Example 1
Preparation of a Suspension of Lanette O
[0073] The procedure was as described in Example 4 except that,
before expansion into the second reactor, the emulsion of the
starting materials was circulated three times through a
high-pressure homogenizer (Cavitron). 31.5 kg of suspension with a
mean particle size of more than 1,000 nm were obtained.
* * * * *