U.S. patent application number 09/917950 was filed with the patent office on 2001-11-22 for polymeric materials and their use.
Invention is credited to Lykke, Mads, Mistry, Kishor Kumar, Simonson, Ole, Symes, Kenneth Charles.
Application Number | 20010044483 09/917950 |
Document ID | / |
Family ID | 27268914 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010044483 |
Kind Code |
A1 |
Symes, Kenneth Charles ; et
al. |
November 22, 2001 |
Polymeric materials and their use
Abstract
A polymeric amphipathic stabilizer is formed of hydrophobic
monomer units and hydrophilic monomer units which comprise
carboxylic free acid or acid salt units and glycidyl or anhydride
units. The glycidyl or anhydride units react onto reactive groups
on polymer particles when dispersed in non-aqueous liquid and
provide improved stability when the particles are subsequently
dispersed in liquid electrolyte.
Inventors: |
Symes, Kenneth Charles;
(West Yorkshire, GB) ; Mistry, Kishor Kumar; (West
Yorkshire, GB) ; Lykke, Mads; (Bronshoj, DK) ;
Simonson, Ole; (Soborg, DK) |
Correspondence
Address: |
SUGHRUE, MION, ZINN, MACPEAK & SEAS, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
WASHINGTON
DC
20037-3213
US
|
Family ID: |
27268914 |
Appl. No.: |
09/917950 |
Filed: |
July 31, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09917950 |
Jul 31, 2001 |
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09635263 |
Aug 9, 2000 |
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09635263 |
Aug 9, 2000 |
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09107407 |
Jun 30, 1998 |
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6127499 |
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Current U.S.
Class: |
523/201 ;
526/317.1; 526/318; 526/318.2 |
Current CPC
Class: |
C11D 17/0013 20130101;
C09K 23/00 20220101; C11D 3/3765 20130101; B01J 13/16 20130101;
C11D 3/37 20130101; C11D 3/3757 20130101; C11D 17/0039 20130101;
B01J 13/20 20130101 |
Class at
Publication: |
523/201 ;
526/317.1; 526/318.2; 526/318 |
International
Class: |
C08F 002/00; C08F
220/06; C08F 122/10; C08F 122/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 1997 |
GB |
9713800.2 |
Jun 30, 1997 |
GB |
9713812.7 |
Oct 9, 1997 |
GB |
9721477.9 |
Claims
1. A polymeric amphipathic stabiliser comprising an addition
polymer of hydrophobic monomer units and hydrophilic monomer units
wherein the hydrophobic monomer units comprise carboxylic free acid
or acid salt units and reactive monomer units selected from (a)
glycidyl monomer units and (b) anhydride monomer units wherein the
amount of anhydride units is either below 10% by weight total
monomer units or is less than 19% by weight total carboxylic avid
monomer units.
2. A stabiliser according to claim 1 in which the amount of the
reactive monomer units is less than 10% by weight total monomer
units.
3. A stabiliser according to claim 1 in which the amount of
reactive monomer units is at least 0.5% by weight.
4. A stabiliser according to claim 1 in which the amount of the
reactive monomer units is 1 to 5%, preferably 1 to 3%, by
weight.
5. A stabiliser according to claim 1 in which the reactive monomer
units are selected from glycidyl acrylate and glycidyl
methacrylate.
6. A stabiliser according to claim 1 in which the reactive monomer
units are maleic anhydride.
7. A stabiliser according to claim 1 in which the hydrophilic
monomer units comprise 5 to 30% by weight carboxylic monomer units
and 0 to 20% by weight hydroxyalkyl monomer units and the reactive
monomer units.
8. A stabiliser according to claim 7 containing at least 10% by
weight of the carboxylic acid monomer units.
9. A stabiliser according to claim 1 formed from at least 20% by
weight C.sub.8-24 (meth) acrylate units and at least 10% by weight
C.sub.1-4 (meth) acrylate or styrene units.
10. A stabiliser according to claim 1 comprising 25 to 70% by
weight C.sub.8-24 alkyl methacrylate, 15 to 40% methyl methacrylate
and/or styrene, 5 to 30% methacrylic acid and/or maleic acid, 0 to
20% hydroxyalkyl (meth) acrylate and 1 to 5% maleic anhydride
and/or glycidyl (meth) acrylate.
11. A dispersion in liquid electrolyte of polymer particles having
reacted onto their surfaces a stabiliser according to claim 1.
12. A dispersion according to claim 11 in which the liquid
electrolyte is an aqueous solution containing at least 3%
electrolyte.
13. A process in which a dispersion is formed in a non-aqueous
liquid containing a stabiliser according to claim 1 of aqueous
polymer particles having reactive groups on their surface which can
be reacted with the glycidyl or anhydride groups as a stabiliser,
this reaction is caused to occur and the particles are then
dispersed in liquid electrolyte.
14. A process according to claim 13 in which the reactive
stabiliser is added to a dispersion in non-aqueous liquid of the
polymer particles wherein the dispersion has been formed in the
non-aqueous liquid in the presence of a different polymeric
stabiliser.
15. A process according to claim 13 in which the dispersion in the
non-aqueous liquid has been formed by reverse phase polymerisation
or interfacial condensation.
Description
[0001] This invention relates to polymeric stabilisers and to the
formation of polymeric particles, i.e. particles having an external
surface of organic polymer, which give improved stability when
dispersed in a liquid, and to dispersions containing them.
[0002] WO97/24179 and WO97/24177 (PCT/GB96/03233 and
PCT/GB96/03231) were not published at the first priority date of
this application but describe various processes and products
wherein a dispersion of polymer particles is formed in the presence
of an amphipathic polymeric stabiliser in a non-aqueous medium, and
then the particles are dispersed in an electrolyte, namely a
detergent concentrate. The entire disclosure of those two
publications and applications is herein incorporated by
reference.
[0003] Those polymeric stabilisers are materials which are known
for use in, for instance, reverse phase polymerisation processes,
either reverse phase emulsion polymerisation or reverse phase bead
polymerisation processes.
[0004] The requirement for effective stabilising properties in
these very different media necessitates the provision of improved
stabilisers suitable for such conditions of media.
[0005] Different types of dispersions are known from, for instance,
GB-A-1,198,052, GB-A-1,231,614, GB-A-1,268,692, GB-A-2,207,681,
AU-A-455,165, U.S. Pat. No. 3,580,880, U.S. Pat. No. 3,875,262,
EP-A-707,018 and EP-A-719,085.
[0006] According to the invention, we provide novel polymeric
amphipathic stabilisers. Amphipathic stabilisers are stabilisers
which contain both hydrophobic groups and hydrophilic groups, both
groups being present in amounts sufficient to allow the stabiliser
to partition at the interface between aqueous and non-aqueous
phases.
[0007] The novel stabilisers of the invention are addition polymers
of hydrophobic monomer units and hydrophilic monomer units wherein
the hydrophilic monomer units comprise carboxylic free acids or
acid salt units and reactive monomer units selected from (a)
glycidyl monomer units and (b) anhydride monomer units wherein the
amount of anhydride monomer units is either below 10% by weight of
total monomer units or is less than 19% by weight of total
carboxylic acid monomer units.
[0008] Because the polymers are addition polymers of glycidyl or
anhydride monomer units, the polymers have a polymeric backbone
carrying the glycidyl or anhydride units as groups which are
pendant to the backbone hydrocarbon chain and which are thus
available for covalent reaction with other reactive groups. The
monomers are all ethylenically unsaturated monomers.
[0009] The amount of the reactive monomer units is usually at least
0.5% and preferably at least 1% (by weight of total monomers). It
may be at least 5%, for instance at least 10%. Usually it is not
above 50% and most usually it is not above 30% by weight of total
monomers. However best results are usually obtained with quite low
amounts of the glycidyl or anhydride monomer, e.g, down to 0.5 or
it and preferably not more than 5% or 10%. Amounts of 0.5 to 5%,
often around 1 to 3%, are often preferred.
[0010] In use, the amphipathic polymer is reacted onto the
polymeric particles in a dispersion, so as to stabilise the
dispersion. We believe that the use of the preferred low amounts of
reactive groups is desirable because it allows the stabilisers to
be permanently attached to the particles at points which are, on a
molecular scale, spaced far apart. This results in the other units
of the polymeric stabiliser being able to adopt their normal
configuration with respect to the particles and, in particular, it
allows for appropriate spacing of the hydrophobic units and the
hydrophilic units, and it allows for appropriate steric
displacement of the units relative to one another and from
particles. If the amount of reactive units in the stabiliser is too
high then there is a tendency for the stabiliser to be bonded, on a
molecular scale, at such closely spaced points around the particles
that the effectiveness of the stabiliser is inhibited.
[0011] The glycidyl monomer can be any ethylenically unsaturated
glycidyl derivative, whereby the ethylenically unsaturated moiety
polymerises into the backbone of the polymer and the glycidyl group
is pendant.
[0012] The glycidyl derivative can be glycidyl acrylate but is
preferably glycidyl methacrylate.
[0013] When the reactive groups are anhydride monomer units, they
are anhydride groups of dicarboxylic acid monomers, for example
maleic acid. They can be introduced by copolymerisation of maleic
anhydride with other monomers such as maleic acid or other
carboxylic acid, or they can be introduced by polymerisation of
maleic anhydride or other anhydride monomer followed by hydrolysis
of some of the groups. The extent of hydrolysis is preferably high,
so that the amount of maleic anhydride or other anhydride groups is
less than 19% and preferably less than 15 or 17%, of the total
carboxylic acid monomer units.
[0014] We have described in, for example, British applications GB
9713812.7 and 9713310.1 on Jun. 30, 1997 and in PCT applications
filed even date herewith claiming priority from those and carrying
references PRL03819WO and PRL03821WO certain processes utilising
stabilisers containing anhydride groups, and it is mentioned
therein that the stabiliser may be derived by hydrolysis of 20 to
80% of the carboxylic acid monomer units.
[0015] The other monomers in the stabiliser are preferably one or
more hydrophobic monomers such as C.sub.1-4 or other lower alkyl
acrylate or methacrylate (preferably methyl methacrylate) and,
especially, fatty alkyl acrylate or methacrylate, or styrene or an
alkyl styrene. The fatty alkyl group can be C.sub.8-32, often
C.sub.10-24 and preferably C.sub.12-18. Any of the hydrophobic
monomers conventionally used in amphipathic stabilisers for reverse
phase polymerisation may be used in the invention.
[0016] The total amount of hydrophobic monomer is usually 30 or 40%
up to 70 or 80%, often 40-60% by weight of monomers. The amount of
fatty alkyl methacrylate is often 20-50% by weight of total
monomers, the remaining hydrophobic monomer preferably being 0-50%,
often 10-40%, methyl methacrylate.
[0017] The hydrophilic monomers which may be used may be ionisable
monomers such as ethylenically unsaturated carboxylic acids, such
as acrylic acid or, especially, methacrylic acid. Instead of or in
addition to using acrylic or methacrylic acid as hydrophilic
monomer, a carboxylic acid such as maleic acid (either as the free
acid or as the anhydride) may be used. Some or all of the
hydrophilic monomer may be a non-ionisable hydrophilic monomer.
Preferably the non-ionisable monomer is an ethylenically
unsaturated hydroxyalkyl monomer, e.g., a hydroxyalkyl ester of an
ethylenically unsaturated acid such as acrylic or methacrylic acid.
The hydroxyalkyl group is preferably a C.sub.1-8 (usually
C.sub.2-4) hydroxyalkyl group such as hydroxyethyl or, preferably,
hydroxypropyl. Preferably it is present as the methacrylate
ester.
[0018] The total amount of hydrophilic monomer may be within the
ranges typically used in amphipathic polymeric stabilisers for
reverse phase polymerisation processes, and may be as described in
the aforementioned PCT publications. For instance the total amount
of ethylenically unsaturated carboxylic acid monomer is generally
at least 5% by weight but usually not above 30% or 40% by weight.
The total amount of ethylenically unsaturated carboxylic acid
monomer and glycidyl monomer is generally in the range 5 to 70%,
preferably 10 or 20% up to 40 or 50% by weight of monomers.
[0019] When hydroxyalkyl monomer is used, the total amount of
hydrophilic monomer may be in the ranges given above for carboxylic
acid plus glycidyl monomers. Preferably the amount of hydroxyalkyl
monomer is 1 to 40%, often 3-20%, by weight of the monomers. If it
is used in conjunction with little or no carboxylic monomer (e.g.,
below lot), the amount of hydroxyalkyl monomer may be 10 or 15% up
to 40%. The hydrophilic monomer component may be a mixture of
methacrylic acid and hydroxypropyl (meth) acrylate in a weight
ratio of 15:1 to 1:5, often 8:1 to 1:1. For instance there may be
15-30% methacrylic acid and 2-10% hydroxypropyl methacrylate.
[0020] Reference should be made to WO97/24179 and WO97/24177 (the
entire disclosure of which is herein incorporated by reference) for
further details of the monomers which can be used and the amounts
of the monomers and for the molecular weight of the stabiliser
polymers.
[0021] The hydrophobic monomers are preferably the water insoluble
nonionic monomers defined therein having a partition coefficient K
between hexane and deionised water as defined therein and
preferably comprise a combination of lower alkyl methacrylate or
styrene (including alkyl styrene) together with fatty alkyl
methacrylate.
[0022] Preferred polymers are formed of at least 20% and usually 25
to 70% by weight C.sub.8-20 (meth) acrylate or other fatty acrylic
monomers, at least 10% and usually 15 to 40% methyl or other
C.sub.1-4 (meth) acrylate and/or styrene (including alkyl styrene
monomers), 5 to 30% by weight (meth) acrylic acid and/or maleic
acid (or other ethylenically unsaturated monomer), 0 to 20%
hydroxypropyl or other hydroxyalkyl (meth) acrylate and a low
amount, generally 1 to 5%, maleic anhydride and/or glycidyl (meth)
acrylate. The total amount of ethylenically unsaturated carboxylic
acid monomer is generally 5 to 30% and the total amount of
hydroxyalkyl monomer (if present) is usually not more 20%, with the
total amount of combined hydrophilic monomers (carboxylic,
hydroxyalkyl and glycidyl anhydride) generally being not more than
40 or 50% by weight.
[0023] A preferred stabiliser is formed of 25-50% fatty alkyl
methacrylate (usually stearyl methacrylate in an amount of 30-40%),
1-5% (usually 2-3%) glycidyl methacrylate, 15-40% (usually 20-30%)
methyl methacrylate, 5-35% (usually 20-30%) methacrylic acid and
0-20% (often 2-20% usually 3-8%) hydroxypropyl methacrylate. For
instance the amounts of the named monomers may be in the
proportions 39:2:27:27:5, by weight.
[0024] The polymers can be used for stabilising a dispersion of
hydrophilic polymer particles in an aqueous medium or a liquid
electrolyte, usually an aqueous electrolyte medium. Thus preformed
polymer made by any convenient technique can be mixed into the
aqueous medium or electrolyte and/or the polymer particles can be
formed in the aqueous electrolyte, for instance by a precipitation
polymerisation.
[0025] The liquid (usually aqueous) electrolyte generally contains
at least 0.5% by weight electrolyte, often at least 3% and
generally at least 5% up to, for instance, 30% or 50% by weight
electrolyte. The electrolyte may be inorganic or organic. The
electrolyte may be monomeric or polymeric. The electrolyte can be a
water soluble ionic polymer, for instance a low molecular weight
cationic or anionic water soluble polymer such as a polymer formed
from water soluble ethylenically unsaturated monomer comprising
water soluble ethylenically unsaturated anionic or cationic monomer
usually in amount of at least 50% and generally at least 80% by
weight and preferably at least 100% by weight of the monomers used
for forming that polymer, or the polymer may be a condensation
polymer for instance it may be polyethylene imine or dicyan diamide
or polyamine polymer.
[0026] The surface of the polymer particles must be reacted with
the reactive stabilisers. This reaction may be with groups that are
chemically bonded into the polymer, for instance as a result of the
choice of monomer from which the surface of the polymer particles
(or the entire volume of the polymer particles) is made, or may be
with material which is trapped in the polymer.
[0027] The polymer particles are preferably first provided as a
dispersion in a non-aqueous liquid. The dispersion may be formed by
dispersing preformed polymer particles into the non-aqueous liquid,
or by forming the particles by polymerisation in the non-aqueous
liquid.
[0028] The particles may be formed of a matrix of a polymer which
carries the reactive groups and which, for instance, extends
throughout the particles. For instance the particles may be aqueous
polymer particles made by polymerising droplets of aqueous monomer
or monomer blend while dispersed in a first non-aqueous liquid (for
instance by reverse phase polymerisation in a non-aqueous liquid)
or the particles may be made by dispersing in a liquid (often a
non-aqueous liquid) polymeric material in liquid form and
converting it to solid particles. For instance the polymeric
material may be introduced as a solution in water or as an emulsion
in water and the resultant aqueous polymer particles of solution or
emulsion may then be converted to solid form, for instance by
distilling or otherwise removing the water from the dispersion of
those particles in the first liquid. The particles may contain an
active ingredient dispersed throughout the matrix.
[0029] As an example, the particles may be formed of a polymer of
acrylic acid, hydroxy ethyl acrylate or a glycidyl acrylate,
optionally copolymerised with other water soluble monomer such as
acrylamide, so that the particles are then formed of an addition
polymer having free carboxylic, hydroxyl or epoxy groups, which
then serve as the reactive groups.
[0030] It is often preferred that the particles should have a
shell-core configuration wherein the core contains an active
ingredient and the shell is formed of a polymer carrying the
reactive groups. The core may include a matrix polymer or may
consist solely of reactive ingredient, and optionally a
non-polymeric carrier or diluent.
[0031] The shell may be formed by any convenient technique. It may
be formed by, for instance, coacervation of one or more polymers,
wherein at least one of the polymers in the coacervate carries
reactive groups. For instance polymers that are used for
coacervation may consist of or include polymers carrying the
carboxylic groups such as polyacrylic acid or natural polymers-such
as-carboxy methyl cellulose.
[0032] Preferably, however, the shell is formed by interfacial
condensation (IFC). Suitable combinations of materials for forming
the shell by IFC are described in PCT/GB96/03233 which is
incorporated herein by reference. Any of these may be used in the
invention. Such methods produce aqueous polymer particles, having a
hydrophilic core.
[0033] The polymer dispersion may be formed in the presence of
amphipathic polymeric stabiliser or any other stabiliser. If
desired, the dispersion can be formed initially in the presence of
a reactive stabiliser as defined herein. Alternatively this may be
added after the initial production of the polymer particles.
[0034] Accordingly, preferred processes according to the invention
are those in which a dispersion is formed in a non-aqueous liquid
in the presence of a reactive stabiliser as defined herein (which
may be present during the initial formation of the dispersion or
may be added after its initial formation) wherein the dispersion
has a dispersed phase of non-aqueous polymer particles having
reactive groups on their surface which can be reacted with the
glycidyl or anhydride groups, this reaction is caused to occur and
the particles are then dispersed in the liquid electrolyte.
[0035] Generally, however, the stabiliser is added to a dispersion
in non-aqueous liquid and which has been formed in the non-aqueous
liquid, often in the presence of a different polymeric stabiliser,
such as a conventional stabiliser formed of un-reactive hydrophilic
and hydrophilic monomer units.
[0036] The polymeric stabiliser concentrates at the interface
between the aqueous and non-aqueous phases in a reverse phase
system and a particular advantage of the use of glycidyl units in
the polymeric stabiliser is that it is possible to promote covalent
reaction between the glycidyl or anhydride units and reactive
groups in the aqueous phase of the dispersion. Accordingly, it is
not essential that the glycidyl or anhydride groups should be
present during the initial formation of the polymeric stabiliser
and, instead of using a glycidyl or anhydride monomer, it is
possible in the invention to react glycidyl substitution onto a
stabiliser which is free of glycidyl groups so as to form glycidyl
monomer units in the polymer.
[0037] The glycidyl groups can react with groups which are bonded
or physically trapped in the surface of the particle and which
contain an active hydrogen (e.g., hydroxyl, carboxylic or amino
groups). For instance they can react with diethylene triamine or
other primary or secondary amino residues, for instance from IFC
reaction using such an amine.
[0038] The reaction of the stabiliser with the polymer particles is
usually caused while the polymer particles are dispersed in the
non-aqueous liquid. Alternatively, if desired the non-aqueous
liquid in which the dispersion is first formed may be changed with
another non-aqueous liquid or with some other liquid such as a
surfactant before the reaction is caused to occur between the
stabiliser and the particles, or even before the stabiliser is
added to the dispersion particles.
[0039] To achieve reaction, the dispersion may be left to react at
ambient temperature for, for instance 3 to 48 hours, but preferably
the reaction is driven by heating, e.g. 30 to 90.degree. C.,
preferably 35 to 60.degree. C. or 70.degree. C., for 1 to 8 hours,
e.g. 3 to 16 hours at 35 to 55.degree. C.
[0040] As a result of utilising a stabiliser which can and does
react covalently with the IFC, coacervate or other polymeric
surface material which is within the dispersed phase, it is
possible to promote the self-stabilising properties of the
dispersed phase. Thus the stabilising polymer is covalently reacted
to the dispersed particles.
[0041] As a result, the stabiliser is not displaced during
subsequent handling of the materials, for instance when the
original dispersion in non-aqueous liquid is subjected to
distillation and/or a solvent swap technique and/or the dispersed
particles are dispersed into an aqueous electrolyte and/or into a
liquid detergent concentrate, for instance all as described in the
WO publications identified above. The dispersions in liquid
electrolyte are novel.
[0042] The use of relatively small amounts (rather than large
amounts) of the glycidyl or anhydride monomer has the result of
reducing the number of points at which the stabiliser molecule can
react on to the receiving IFC or other surface, and so tends to
promote the stabiliser to extend out from the surface. The use of
non-ionisable hydrophilic monomer has the advantage of reducing the
effect of the ionic content (of the liquid in which the particles
are dispersed) on the stabilising properties. Accordingly such
monomer can impart solvating or hydrophilic properties which are
not significantly reduced by, for instance, changing the
environment from a strongly alkaline detergent to a near neutral
detergent concentrate.
[0043] The novel stabilisers (especially those containing
hydroxyalkyl groups and/or low glycidyl content) cause particularly
good stabilisation of amine-TPC or other interfacial condensation
(IFC) shell particles, for instance in aqueous detergent
concentrates. The invention improves stability against
agglomeration and/or settling during storage.
[0044] When the polymer particles are formed by other techniques,
such as reverse phase polymerisation, they may be made by reverse
phase polymerisation of an aqueous solution of ethylenically
unsaturated monomer or monomer blend in a non-aqueous liquid in
conventional manner, in which event the monomers which are being
polymerised can include, for instance, ethylenically unsaturated
anionic monomers, ethylenically unsaturated cationic monomers or
ethylenically unsaturated water soluble anionic monomer (such as
acrylamide) and which may be selected to include monomer that will
provide an addition polymer having reactive groups that can react
with anhydride or glycidyl groups of the stabiliser. For instance
the particulate polymer may be formed from monomers that provide
free carboxylic, hydroxyl or epoxy groups.
[0045] The novel stabilisers can be made by polymerisation and to a
molecular weight (typically 10,000 to 200,000 measured by Gel
Permeation Chromatography) similar to conventional amphipathic
stabilisers which are well known for reverse phase or other
polymerisation processes.
[0046] The particles which are stabilised in the invention are
usually relatively small, for instance having a size at least 90%
by weight below 30 .mu.m, preferably below 10 or 20 .mu.m, such
that they can be provided as a substantially stable dispersion in
the detergent concentrate or other aqueous electrolyte. The
invention reduces or eliminates the risk of the particles
aggregating and/or sedimenting, both at low concentrations (e.g.,
down to 0.1% by weight) and at higher concentrations (e.g., 5% or
even much higher such as 30% or 50% in some liquids. However, the
invention also includes the use of the stabilisers to reduce
aggregation in bead polymerisation or in other processes where the
particles have a size of above 30 .mu.m, for instance at least 90%
in the range 100 to 1000 .mu.m.
[0047] The use of the stabiliser of the invention minimises the
risk of aggregation of the particles and increases the stability of
a dispersion of the particles. In particular, the use of the
stabilisers is of a special value in processes and products as
described in WO97/24179 and WO97/24177 and in the PCT application
filed today reference PRL03820WO claiming priority from GB
9713310.1 and in the PCT application filed today reference
PRL03821WO claiming priority from GB 9713804.4, the entire
disclosure of which is herein incorporated by reference. Thus, as
described in those, the polymer particles can be made by
interfacial condensation as a shell core configuration with a
detergent enzyme entrapped in the core, with the result that a
dispersion concentrate in which the particles are dispersed has
improved stability and improved separation of the encapsulated
enzyme from other materials, such as enzymes, in the continuous
phase, all as discussed in those applications.
[0048] In particular those applications describe
[0049] (a) a process for making a dispersion in liquid electrolyte
of particles having a size below 30 .mu.m, the process comprising
forming a dispersion in a first liquid of particles which have a
size of below 30 .mu.m and which have a core containing a detergent
active ingredient and a shell which has been formed by interfacial
condensation and which has an outer surface which includes reactive
groups, and covalently reacting a reactive stabiliser material with
some of the reactive groups and thereby forming a dispersion of the
particles with the stabiliser material covalently bonded on to the
outer surface of the shell of the particles, and dispersing the
resultant self-stabilised particles into the liquid electrolyte,
and
[0050] (b) a liquid detergent concentrate containing a dispersion
of particles having a size below 30 .mu.m wherein the particles
have a shell core configuration, the shell has been made by
interfacial condensation and has an outer surface which includes
reactive groups, and a reactive stabiliser is covalently bonded
with some of the reactive groups on to the surface of the
particles.
[0051] In each of these, the reactive stabiliser may be as
described herein.
[0052] The following are examples of the invention
EXAMPLE 1
[0053] Amphipathic polymer is made by conventional polymerisation
in hydrocarbon of a monomer blend of 65% stearyl methacrylate,
17.5% styrene, 15.05 maleic acid and 2.5% maleic anhydride. This is
stabiliser A.
EXAMPLE 2
[0054] Amphipathic stabiliser is made by solution polymerisation in
a hydrocarbon by conventional techniques of a monomer blend formed
of 55% by weight stearyl methacrylate, 33% methyl methacrylate, 10%
methacrylic acid and 2% by weight glycidyl acrylate.
EXAMPLE 3
[0055] An oil phase is prepared by diluting 46 g of 20% un-reactive
amphipathic emulsion stabiliser with 586 gm of Isopar G solvent (a
hydrocarbon).
[0056] An aqueous dispersion at pH 5.0 (900 g) comprising
precipitated Savinase enzyme, sodium polyacrylate homopolymer,
sodium sulphate and boric acid is added to the oil phase under a
high shear Silverson mixer to form a water-in-oil emulsion with
mean droplet size 3 microns. During this step, the temperature of
emulsion is kept below 40.degree. C. After formation of the
emulsion, extra 306 g Isopar G and 25 g diethylenetriamine are
added with high shear mixing.
[0057] A 3% solution of terephthaloyl chloride in Isopar G (562 g)
is prepared and this is contacted with the above enzyme emulsion by
means of an in-line static mixer to produce polyamide shell
capsules.
[0058] Next, the capsule suspension is warmed to 40.degree. C. and
182 g of 20 glycidyl polymeric stabiliser B is added. The mixture
is then stirred at 40.degree. C. for 16 hours to attach the
polymeric stabiliser to the capsule outer shell.
[0059] The modified capsules formed above are then placed under
vacuum distillation to remove volatile solvent and the volatile
solvent is replaced by a less volatile hydrocarbon Isopar M oil 300
gm.
[0060] The final product is Savinase capsules suspension in oil
having 40 KNPU/g enzyme activity.
[0061] The improved enzyme capsules are dosed into commercial
heavy-duty liquid detergent at 1.0 KNPU/g enzyme activity and
subjected to accelerated storage test at 40.degree. C. After 4
weeks, the capsules remain discrete and uniformly dispersed in the
detergent medium.
EXAMPLE 4
[0062] An aqueous solution of 50% polyethylene imine (500 g) is
added under agitation into an oil phase (500 g) comprising of 10 g
Span 85 and 490 g Exxson D-40 hydrocarbon solvent. The coarse
emulsion formed is then passed through a high pressure homogeniser
to produce water-in-oil emulsion with mean droplet size of 0.5
microns. Next, 5 mls of 40% glutaraldehyde solution is added and
the emulsion warmed to 55% to cross-link the polyethylene imine
polymer.
[0063] After the above cross-linking reaction, 50 g of 20%
stabiliser B in Exxsol D-40 is added and the emulsion kept at
50.degree. C. for a further 3 hours. This step covalently bonds the
stabilising polymer onto the cross-linked polymer particles.
[0064] When the cross-linked polymer emulsion is added to 10%
ammonium sulphate solution, the polymer particles disperse and
remain uniformly suspended. Even after 3 weeks storage, there is no
sign of any instability.
[0065] As a comparison, the procedure is repeated except 50 g
Exxsol D-40 solvent is added instead of glycidyl stabiliser to the
cross-linked polymer particles in oil. When the polymer particles
are added to the 10% ammonium salt solution, the polymer particles
disperse but aggregate into large flocs after only 1 day
storage.
* * * * *