Note: Descriptions are shown in the official language in which they were submitted.
PF 72435 CA 02856785 2014-05-23
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Microcapsule dispersion containing microcapsules having a hydrophilic capsule
core
Description
The present invention relates to microcapsule dispersions comprising
microcapsules
comprising a hydrophilic capsule core and a capsule wall polymer which is
obtainable
by polymerization of a monomer composition comprising
25 to 95% by weight of one or more C1-C24-alkyl and/or glycidyl esters of
acrylic acid
and/or methacnilic acid
5 to 75% by weight of one or more hydrophilic monomers selected from acrylic
acid
esters and/or methacrylic acid esters which carry hydroxy
and/or carboxy groups, and allylgluconamide
0 to 40% by weight of one or more compounds having two or more ethylenically
unsaturated radicals,
where the microcapsules are dispersed in a hydrophobic diluents, to the
microcapsules, and to a method for producing them and to their use for the
delayed
release of active ingredients for construction, cosmetics or crop protection
applications.
Microcapsules with a hydrophobic capsule core are known for numerous
applications.
EP 457 154 teaches microcapsules with a core oil comprising color formers and
walls
which are obtained by polymerization of methacrylates in an oil-in-water
emulsion. EP
1029018 describes microcapsules with capsule wall polymers based on
(meth)acrylates and a capsule core of lipophilic waxes as latent heat storage
materials.
Furthermore, WO 2011/064312 teaches microcapsules with crop protection active
ingredients dissolved in a hydrophobic oil as capsule core and likewise a
capsule wall
based on (meth)acrylate.
In contrast to the oil-in-water emulsions in which the oil is the disperse
phase, i.e. the
discontinuous phase, and the water is the continuous phase, encapsulation
methods
are also known in which the two phases are swapped. These methods are also
referred to as inverse microencapsulation.
DE 10120480 describes such an inverse encapsulation. It teaches microcapsules
with
a capsule core comprising water-soluble substances and a capsule wall of
melamine/formaldehyde resins. Furthermore, WO 03/015910 teaches microcapsules
with a capsule core comprising water-soluble substances and a capsule wall of
polyureas.
EP-A-0 148 169 describes microcapsules with a water-soluble core and a
polyurethane
wall which are produced in a vegetable oil. As capsule core material, as well
as
herbicides, water-soluble dyes, inter alia, are mentioned.
,
PF 72435 CA 02856785 2014-05-23
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However, there thus continues to be a need for microcapsules with a capsule
core
comprising water which can be used, for example, as pore formers in
construction
materials. It is also desirable to protect in this way acid, the release of
which can be
controlled as accelerator for, for example, chipboard. Delayed release of
water-soluble
active ingredients for crop protection or cosmetic applications is also of
interest.
It was an object of the present invention to encapsulate aqueous solutions or
water
itself.
Accordingly, the microcapsules described above and/or their dispersions in a
hydrophobic diluent, and a method for producing them have been found.
The microcapsules according to the invention comprise a capsule core and a
capsule
wall. The capsule core consists predominantly, to more than 95% by weight, of
water or
aqueous solutions. The average particle size of the capsules (Z average by
means of
light scattering) is 0.5 to 50 pm. According to one preferred embodiment, the
average
particle size of the capsules is 0.5 to 15 pm, preferably 0.5 to 10 pm. In
this connection,
preferably 90% of the particles have a particle size of less than twice the
average
particle size.
The weight ratio of capsule core to capsule wall is in general from 50 : 50 to
95: 5.
Preference is given to a core/wall ratio of 70 : 30 to 93 : 7.
A hydrophilic capsule core (capsule core material) is to be understood as
meaning
water, and aqueous solutions of water-soluble compounds whose content is at
least
10% by weight of a water-soluble compound. Preferably, the aqueous solutions
are at
least 20% by weight strength.
The water-soluble compounds are, for example, organic acids or salts thereof,
inorganic acids, inorganic bases, salts of inorganic acids such as sodium
chloride or
sodium nitrate, water-soluble dyes, agrochemicals such as Dicamba ,
flavorings,
pharmaceutical active ingredients, fertilizers or cosmetic active ingredients.
Preferred
hydrophilic capsule core materials are water, and aqueous solutions of organic
acids
such as acetic acid, formic acid, propionic acid and methanesulfonic acid,
and/or salts
thereof, inorganic acids such as phosphoric acid and hydrochloric acid, and
salts of
inorganic acids, and sodium silicate.
Depending on the thickness of the capsule wall, which is influenced by the
chosen
process conditions and also amount of feed materials, the capsules are
impermeable
or sparingly permeable for the hydrophilic capsule core material. With
sparingly
permeable capsules, a controlled release of the hydrophilic capsule core
material can
PF 72435 CA 02856785 2014-05-23
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be achieved. The water forming the capsule core will often evaporate from
isolated
microcapsules, i.e. microcapsules freed from the hydrophobic diluent, over the
course
of time.
Where -(meth)acrylates is used within the context of this application, both
the
corresponding -acrylates, i.e. the derivatives of acrylic acid, and also the -
methacrylates, the derivatives of methacrylic acid, are intended.
The polymers of the capsule wall comprise generally at least 25% by weight, in
preferred form at least 30% by weight and in particularly preferred form at
least 40% by
weight, and also in general at most 95% by weight, preferably at most 90% by
weight
and in particularly preferred form at most 80% by weight, of C1¨C24¨alkyl
and/or glycidyl
esters of acrylic acid and/or methacrylic acid (monomers I) in copolymerized
form,
based on the total weight of the monomers.
According to the invention, the polymers of the capsule wall generally
comprise at least
5% by weight, preferably at least 10% by weight, preferably at least 15% by
weight,
and in general at most 75% by weight, preferably at most 60% by weight and, in
a
particularly preferred form, at most 55% by weight, of one or more hydrophilic
monomers (II) selected from acrylic acid esters which carry hydroxy and/or
carboxy
groups, methacrylic acid esters which carry hydroxy and/or carboxy groups, and
allylgluconamide, based on the total weight of the monomers, in copolymerized
form.
In addition, the polymers can preferably comprise at least 5% by weight,
preferably at
least 10% by weight, preferably at least 15% by weight, and in general at most
40% by
weight, preferably at most 35% by weight and, in a particularly preferred
form, at most
30% by weight or one or more compounds having two or more ethylenically
unsaturated radicals (monomers III) in copolymerized form, based on the total
weight of
the monomers.
Furthermore, up to 5% by weight of other monomers IV, which are different from
the
monomers I, II and III, may be present in the capsule wall in copolymerized
form.
Preferably, the monomer composition consists of the monomers I and II, and
optionally
the monomers III, and optionally the monomers IV.
Suitable monomers I are C1¨C24¨alkyl esters of acrylic and/or methacrylic
acid, and
also the glycidyl esters of acrylic acid and/or methacrylic acid. Preferred
monomers I
are methyl, ethyl, n¨propyl and n¨butyl acrylate, and the corresponding
methacrylates.
In general, the methacrylates are preferred. Particular preference is given to
Cl-C4-
alkyl methacrylates. According to a further embodiment, glycidyl methacrylate
is
preferred.
PF 72435 CA 02856785 2014-05-23
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According to a particularly preferred embodiment, monomer I is methyl
methacrylate,
optionally in a mixture with glycidyl methacrylate and/or one or more C2-C24-
alkyl esters
of acrylic acid and/or methacrylic acid. The monomer composition particularly
preferably comprises 25-40% by weight of methyl methacrylate.
Monomers II are selected from acrylic acid esters which carry hydroxyl and/or
carboxy
groups, methacrylic acid esters which carry hydroxyl and/or carboxy groups,
and
allylgluconamide. They are preferably (meth) acrylic acid esters which carry
at least
one radical selected from carboxylic acid and hydroxyl radical. The preferred
(meth)
acrylic acid esters are hydrophilic, i.e. they have a solubility in water of
>50g/I at 20 C
and atmospheric pressure.
The monomers II used are preferably hydroxyalkyl acrylates and hydroxyalkyl
methacrylates such as 2-hydroxyethyl acrylate and methacrylate, hexapropyl
acrylate
and methacrylate, hydroxybutyl acrylate and diethylene glycol monoacrylate.
Further preferred hydrophilic monomers II are acrylamidoalkylpolyhydroxyacid
amides,
methacrylamidoalkyl-polyhydroxy acid amides, N-acryl-glycosylamines and N-
methacryl-glycosylamines.
The preparation of the acrylamidoalkyl-polyhydroxy acid amides and of the
methacrylamidoalkyl-polyhydroxyacid amides is known and described for example
in
WO 2010/118951. Furthermore, the preparation of the N-acryl-glycosylamines and
N-
methacryl-glycosylamines is known and described for example in WO 2010/118951.
Thus, the preparation of N-acryl-glycosylamines and N-methacryl-glycosylamines
takes
place in two steps by reacting an aldehyde sugar with a primary aliphatic
amine or
ammonia to give the corresponding glycosylamine, and reacting the resulting N-
glycosylamine with the acrylic anhydride or methacrylic anhydride to give the
N-acryl-
glycosylamine or N-methacryl-glycosylamine, respectively. According to the
invention,
the two process steps are carried out directly after one another, i.e. without
interim
isolation.
Hereinbelow, aldehyde sugars are to be understood as meaning reducing sugars
which
carry an aldehyde group in their open-chain form. The aldehyde sugars used
according
to the invention are open-chain or cyclic mono- and oligosaccharides from
natural and
synthetic sources with an aldehyde radical and/or semiacetal thereof. In
particular, the
aldehyde sugars selected from monosaccharides and oligosaccharides in
optically pure
form are preferred. They are also suitable as stereoisomer mixture.
,
PF 72435 CA 02856785 2014-05-23
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Monosaccharides are selected from aldoses, in particular aldo-pentoses and
preferably
aldo-hexoses. Suitable monosaccharides are, for example, arabinose, ribose,
xylose,
mannose and galactose, in particular glucose. Since the monosaccharides are
reacted
in aqueous solution, they are present, on account of the mutarotation, both in
ring-like
5 semiacetal form and also, to a certain percentage, in open-chain aldehyde
form.
Preferably, the aldehyde sugar is an oligosaccharide. Oligosaccharides are
understood
as meaning compounds having 2 to 20 repeat units. Preferred oligosaccharides
are
selected from di-, tri-, tetra-, penta-, and hexa-, hepta-, octa, nona- and
decasaccharides, preferably saccharides having 2 to 9 repeat units. The
linkage within
the chains takes place 1,4-glycosidically and optionally 1,6-glycosidically.
The aldehyde
sugars, even if they are oligomeric aldehyde sugars, have one reducing group
per
molecule.
Preferably, the aldehyde sugars (saccharides) used are compounds of the
general
formula I
OH OH
HO ____________________ ---0) 0 ____OH
(I)
OH OH .._ n OH OH
¨
in which n is the number 0, 1, 2, 3, 4, 5, 6, 7 or 8.
The oligosaccharides in which n is an integer from 1 to 8 are particularly
preferred. In
this connection, it is possible to use oligosaccharides with a defined number
of repeat
units. Examples of oligosaccharides which may be mentioned are lactose,
maltose,
isomaltose, maltotriose, maltotetraose and maltopentaose.
Preferably, mixtures of oligosaccharides with a different number of repeat
units are
selected. Mixtures of this type are obtainable by hydrolysis of a
polysaccharide,
preferably of celluloase or starch, such as enzymatic or acidically catalyzed
hydrolysis
of cellulose or starch. Vegetable starch consists of amylose and amylopectin
as main
constituent of the starch. Amylose consists of predominantly unbranched chains
of
glucose molecules which are 1,4-glycosidically linked to one another.
Amylopectin
consists of branched chains in which, besides the 1,4-glycosidic linkages,
there are
additionally 1,6-glycosidic linkages which lead to branches. Also of
suitability according
to the invention are hydrolysis products of amylopectin as starting compound
for the
method according to the invention and are encompassed by the definition of
oligosaccharides.
PF 72435 CA 02856785 2014-05-23
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Primary aliphatic amines suitable for the reaction may be linear or branched.
Within the
context of this invention, primary aliphatic amines are aliphatic monoamines,
preferably
saturated monoamines, with one primary amino group. The saturated aliphatic
radical
is generally an alkyl radical, having preferably 1 to 8 carbon atoms, which
can be
interrupted by 0 atoms and which can optionally carry one or two carboxyl
groups,
hydroxyl groups and/or carboxamide groups.
-
Suitable primary aliphatic amines which are substituted with hydroxyl,
carboxyl or
carboxamide which may be mentioned are alkanolamines such as ethanolamine, and
amino acids such as glycine, alanine, phenyialanine, serine, asparagine,
glutamine,
asparatic acid and glutamic acid. Suitable primary aliphatic amines, the
alkylene radical
of which is interrupted with oxygen, are preferably 3-methoxypropylamine, 2-
ethoxy-
ethylamine and 3-(2-ethylhexyloxy)propylamine.
As primary aliphatic amines, preference is given to using C1-C8-alkylamines,
in
particular C1-C4-alkylamines, such as ethylamine, 1-aminopropane, 2-
aminopropane,
1-aminobutane, 2-aminobutane, in particular methylamine.
Preferably, the primary aliphatic amines are selected from methylamine and
ethanolamine. Furthermore, the reaction with ammonia or mixtures of ammonia
with
primary aliphatic amines is preferred.
The anhydrides used are methacrylic anhydride and acrylic anhydride.
The preparation of the acrylamidoalkyl-polyhydroxy acid amides or
methacrylamidoalkyl-polyhydroxy acid amides takes place schematically in two
steps:
in the first step of the reaction of the polyhydroxy acid lactone with the
aliphatic diamine
to give the corresponding aminoalkylaldonamide and in the second step of the
reaction
of the aminoalkylaldonamide with methacrylic anhydride or acrylic anhydride to
give the
unsaturated methacryl- or acrylamidoalkylpolyhydroxy acid amide according to
the
invention. Optionally, an interim isolation may be advantageous.
Hereinbelow, polyhydroxy acid lactone is to be understood as meaning lactones
of
saccharides from a natural and synthetic source oxidized merely on the
anomeric
carbon. Polyhydroxy acid lactones of this type can also be referred to as
lactones of
aldonic acids. The polyhydroxy acid lactones can be used individually or in
their
mixtures.
The saccharides are selectively oxidized only on the anomeric center.
Processes for
the selective oxidation are generally known and are described, for example, in
J.
PF 72435 CA 02856785 2014-05-23
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7
Lonnegren, I. J. Goldstein, Methods Enzymology, 242 (1994) 116. For example,
the
oxidation can be carried out with iodine in an alkaline medium or with
copper(II) salts.
Suitable saccharides are the aforementioned saccharides, in particular the
saccharides
specified as being preferred.
Suitable aliphatic diamines can be linear, cyclic or branched. Within the
context of this
invention, aliphatic diamines are diamines having two primary or secondary
amino
groups, preferably having one primary and one further primary or secondary
amino
group, which are bonded with one another via an aliphatic, preferably
saturated
bivalent radical. The bivalent radical is generally an alkylene radical,
having preferably
2 to 10 carbon atoms, which can be interrupted by 0 atoms and which can
optionally
carry one or two carboxyl groups, hydroxyl groups and/or carboxamide groups.
Furthermore, aliphatic diamines are also understood as meaning cycloaliphatic
diamines.
Examples of suitable aliphatic diamines which are substituted with hydroxyl,
carboxyl or
carboxamide which may be mentioned are N-(2-aminoethyl)ethanolamine, 2,4-
diaminobutyric acid or lysine.
The suitable aliphatic diamines, the alkylene radical of which is interrupted
with oxygen,
are preferably a,w-polyether diamines in which the two amino groups are at the
chain
ends of the polyether. Polyether diamines are preferably the polyethers of
ethylene
oxide, of propylene oxide and of tetrahydrofuran. The molecular weights of the
polyether diamines are in the range from 200 - 3000 g/mol, preferably in the
range
from 230 - 2000 g/mol.
Preference is given to using aliphatic C2-C8-diamines and cycloaliphatic
diamines, such
as 1,2-diaminoethane, 1,3-diaminopropane, 1,5-diaminopentane, 1,6-
diaminohexane,
N-methyl-1,3-diaminopropane, N-methyl-1,2-diaminoethane, 2,2-dimethylpropane-
1,3-
diamine, diaminocyclohexane, isophoronediamine and 4,4"-diaminodicyclohexyl-
methane.
Compounds with two or more ethylenically unsaturated radicals (monomers III)
act as
crosslinkers. Preference is given to using monomers with vinyl, allyl, acryl
and/or
methacryl groups.
Suitable monomers III with two ethylenically unsaturated radicals are, for
example,
divinylbenzene and divinylcyclohexane and preferably the diesters of diols
with acrylic
acid or methacrylic acid, also the diallyl and divinyl ethers of these diols.
By way of
example, mention may be made of ethanediol diacrylate, ethylene glycol
dimethacrylate, 1,3-butylene glycol dimethacrylate, diethylene glycol
diacrylate,
dipropylene glycol diacrylate, methallylmethacrylamide, allyl acrylate and
allyl
PF 72435 CA 02856785 2014-05-23
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methacrylate. Particular preference is given to propanediol diacrylate,
butanediol
diacrylate, pentanediol diacrylate and hexanediol diacrylate and the
corresponding
methacrylates.
Monomers III with three or more, generally 3, 4 or 5, ethylenically
unsaturated radicals
are, for example, the polyesters of polyols with acrylic acid and/or
methacrylic acid,
also the polyallyl and polyvinyl ethers of these polyols. Preference is given
to
monomers III with three or more ethylenically unsaturated radicals such as
trimethylolpropane triacrylate and methacrylate, pentaerythritol Wally! ether,
pentaerythritol tetraallyl ether, pentaerythritol triacrylate and
pentaerythritol
tetraacrylate, and their technical-grade mixtures. For example, as a rule,
pentaerythritol
tetraacrylate is present in technical-grade mixtures in a mixture with
pentaerythritol
triacrylate and small amounts of oligomerization products.
Suitable other monomers IV are monoethylenically unsaturated monomers which
are
different from the monomers I and II, such as styrene,13-methylstyrene, vinyl
acetate,
vinyl propionate and vinylpyridine suitable.
The water-soluble monomers IV are particularly preferably acrylic acid,
methacrylic
acid, acrylonitrile, methacrylamide, itaconic acid, maleic acid, maleic
anhydride, N-
vinylpyrrolidone, and acrylamido-2-methylpropanesulfonic acid. In addition,
mention is
to be made in particular of N-methylolacrylamide, N-methylolmethacrylamide,
dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate.
Preference is given to using monomer compositions consisting of
25 to 90% by weight of one or more Ci-C24-alkyl and/or glycidyl esters of
acrylic acid
and/or methacrylic acid,
5 to 75% by weight of one or more monomers selected from acrylic
acid and/or
methacrylic acid esters which carry hydroxy and/or carboxy
groups, and allylgluconamide
15 to 40% by weight of one or more compounds having two or more ethylenically
unsaturated radicals
0 to 10% by weight of one or more other monomers
for the formation of the capsule wall polymer by free-radical polymerization.
Likewise preference is given to using monomer compositions comprising,
preferably
consisting of
25 to 95% by weight of one or more C1-C24-alkyl and/or glycidyl esters of
acrylic acid
and/or methacrylic acid,
PF 72435 CA 02856785 2014-05-23
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30 to 75% by weight of one or more monomers selected from acrylic acid and/or
methacrylic acid esters which carry hydroxy and/or carboxy
groups, and allylgluconamide
0 to 40% by weight of one or more compounds having two or more
ethylenically
unsaturated radicals
0 to 5% by weight of one or more other monomers
for the formation of the capsule wall polymer by free-radical polymerization.
The microcapsules according to the invention are obtainable by preparing a
water-in-oil
emulsion comprising hydrophobic diluent as continuous phase, and the
hydrophilic
capsule core material and the monomers and subsequent free-radical
polymerization of
the monomers to form the capsule wall polymer. The monomers can be used here
in
the form of a mixture. However, it is likewise possible to meter them in
separately,
depending on their hydrophilicity, i.e. solubility in water, in a mixture with
the capsule
core material and in a mixture with the hydrophobic diluent. Thus, the
monomers ll are
preferably metered in in a mixture with the hydrophilic capsule core material.
The
monomers I are preferably metered in in a mixture with the hydrophobic
diluent.
The continuous phase of the emulsion usually comprises surface-active
substances in
order to avoid coalescence of the droplets. In this emulsion, the water or the
aqueous
solution is the discontinuous later disperse phase and the hydrophobic diluent
the
continuous phase. The emulsified droplets here have a size which corresponds
approximately to the size of the subsequent microcapsules. The wall formation
takes
place as a result of the polymerization of the monomer composition which is
started by
free-radical starters.
Hereinbelow, hydrophobic diluent is understood as meaning diluents which have
a
solubility in water of <19/I, preferably <0.5 g/I at 20 C and standard
pressure.
Preferably, the hydrophobic diluent is selected from
- cyclohexane,
- glycerol ester oils,
- hydrocarbon oils, such as paraffin oil, diisopropylnaphthalene,
purcellin oil,
perhydrosqualene and solutions of microcrystalline waxes in hydrocarbon oils,
- animal or vegetable oils,
- mineral oils, the distillation start-point of which under atmospheric
pressure is ca.
250 C and the distillation end-point of which is 410 C, such as e.g. Vaseline
oil,
- esters of saturated or unsaturated fatty acids, such as alkyl
myristate, e.g.
isopropyl myristate, butyl myristate or cetyl myristate, hexadecyl stearate,
ethyl
palmitate or isopropyl palmitate and cetyl ricinoleate,
- silicone oils, such as dimethylpolysiloxane, methylphenylpolysiloxan and
the
silicone glycol copolymer,
PF 72435 CA 02856785 2014-05-23
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- fatty acids and fatty alcohols or waxes such as Carnauba
wax, Candellila wax.
beeswax, microcrystalline wax, ozokerite wax and Ca, Mg and Al oleates,
myristates, linoleates and stearates.
5 Glycerol ester oils are understood as meaning esters of saturated or
unsaturated fatty
acids with glycerol. Mono-, di- and triglycerides, and their mixtures are
suitable.
Preference is given to fatty acid triglycerides. Fatty acids which may be
mentioned are,
for example, Cs-Cu-fatty acids such as hexanoic acid, octanoic acid, decanoic
acid and
dodecanoic acid. Preferred glycerol ester oils are C6-C12-fatty acid
triglycerides, in
10 particular octanoic acid and decanoic acid triglycerides, and their
mixtures. Such an
octanoyl glyceride/decanoyl glyceride mixture is for example Miglyol 812 from
I-101s.
In order to obtain a stable emulsion, surface-active substances such as
protective
colloids and/or emulsifiers are required. As a rule, surface-active substances
are used
which are miscible with the hydrophobic phase.
Preferred protective colloids are linear block copolymers with a hydrophobic
structural
unit of a length > 50A, alone or in mixtures with other surface-active
substances. The
linear block copolymers are given by the general formula
in which w is 0 or 1, x is 1 or more, y is 0 or 1 and z is 0 or 1 and A is a
hydrophilic
structural unit with a solubility in water at 25 C> 1% by weight ( > 10g/1)
and a
molecular weight of from 200 to 50 000, which is covalently bonded to the B
blocks,
and B is a hydrophobic structural unit with a molecular weight of from 300 to
60 000
and a solubility < 1% by weight in water at 25 C and can form covalent bonds
to A; and
in which C and D are end groups which, independently of one another, can be A
or B.
The end groups can be identical or different and are dependent on the
preparation
process.
Examples of hydrophilic groups are polyethylene oxides, poly(1,3-dioxolane),
copolymers of polyethylene oxide or poly(1,3-dioxolane), poly(2-methyl-2-
oxazoline),
poly(glycidyltrimethylammonium chloride) and polymethylene oxide.
Examples of hydrophobic groups are polyesters in which the hydrophobic moiety
is a
steric barrier 50 A, preferably 75 A, in particular .100 A. The polyesters are
derived
from components such as 2-hydroxybutanoic acid, 3-hydroxybutanoic acid, 4-
hydroxybutanoic acid, 2-hydroxycaproic acid, 10-hydrodecanoic acid, 12-
hydroxydodecanoic acid, 16-hydroxyhexadecanoic acid, 2-hydroxyisobutanoic
acid, 2-
(4-hydroxyphenoxy)propionic acid, 4-hydroxyphenylpyruvic acid, 12-
hydroxystearic
acid, 2-hydroxyvaleric acid, polylactones of caprolactone and butyrolactone,
polylactams of caprolactam, polyurethanes and polyisobutylenes. Preferably,
the
PF 72435 CA 02856785 2014-05-23
11
water-in-oil emulsion is stabilized with a 12-hydroxystearic acid block
copolymer as
linear block copolymer.
The linear block copolymers comprise both hydrophilic and hydrophobic units.
The
block polymers have a molecular weight above 1000 and a length of the
hydrophobic
moiety of 50 A calculated in accordance with the law of cosines. These
parameters
are calculated for a stretched-out configuration taking into consideration the
binding
lengths and angles given in the literature. The preparation of these units is
generally
known. Preparation processes are, for example, condensation reaction of
hydroxy
acids, condensations of polyols such as diols with polycarboxylic acids such
as
dicarboxylic acids, Also of suitability is the polymerization of lactones and
lactams, and
also the reaction of polyols with polyisocyanates. Hydrophobic polymer units
are
reacted with the hydrophilic units as generally known, for example by
condensation
reaction and coupling reaction. The preparation of such block copolymers is
described
for example in US 4 203 877, to which reference is expressly made.
Preferably, the fraction of linear block copolymer is 20-100% by weight of the
total
amount of surface-active substance used.
Suitable surface-active substances are also the emulsifiers customarily used
for water-
in-oil emulsions, for example
- C12-C18-sorbitan fatty acid esters,
esters of hydroxystearic acid and C,2-C30 fatty alcohols,
mono- and diesters of C12-C18-fatty acids and glycerol or polyglycerol,
- condensates of ethylene oxide and propylene glycols,
oxypropylenated/oxyethylenated C12-C20-fatty alcohols,
- polycyclic alcohols, such as sterols,
aliphatic alcohols with a high molecular weight, such as lanolin,
- mixtures of oxypropylenated/polyglycerolated alcohols and magnesium
isostearate,
succinic esters of polyoxyethylated or polyoxypropylenated fatty alcohols,
magnesium, calcium, lithium, zinc or aluminum lanolate and stearate,
optionally
as a mixture with hydrogenated lanolin, lanolin alcohol, or stearic acid or
stearyl
alcohol.
Emulsifiers of the Span series (ICI Americas, Inc.) have proven to be
particularly
advantageous. These are cyclized sorbitol sometimes polyesterified with a
fatty acid,
where the basic framework can also be substituted with further radicals known
from
surface-active compounds, for example with polyoxyethylene. By way of example,
the
sorbitan esters with lauric acid, palmitic acid, stearic acid and oleic acid
may be
mentioned, such as Span 80 (sorbitan monooleate) and Span 60 (sorbitan
monostearate).
PF 72436 CA 02856785 2014-05-23
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In a preferred embodiment oxypropylenated/oxyethylenated C12-C20-fatty
alcohols are
used as mixing component with further surface-active substances. These fatty
alcohols
generally have 3 to 12 ethylene oxide or propylene oxide units.
Preferably, C12-C18-sorbitan fatty acid esters are used as emulsifier. These
can be used
individually, in their mixtures and/or as mixtures with other aforementioned
emulsifier
types. Preferably, the fraction of sorbitan fatty acid esters is 20-100% by
weight of the
total amount of surface-active substance used.
In a preferred embodiment, a mixture of surface-active substances comprising
the
above-defined linear block copolymers and C12-C18-sorbitan fatty acid esters
is
selected.
Particularly preferably, a mixture of surface-active substances comprising the
linear
block copolymers C12-C18-sorbitan fatty acid esters and
oxypropylenated/oxyethylenated C12-C20-fatty alcohols is selected.
Preference is given to those mixtures comprising 20 to 95% by weight, in
particular 30
to 75% by weight, of linear block copolymer and 5 to 80% by weight, in
particular 25 to
70% by weight, of C12-C18-sorbitan fatty acid esters, based on the total
amount of
surface-active substance. The fraction of oxypropylenated/oxyethylated Cu-Cm-
fatty
alcohol is preferably 0 to 20% by weight.
In particular, preference is given to mixtures of surface-active substances
comprising
essentially 40 to 60% by weight of linear block copolymer, 30 to 50% by weight
of C12-
C18-sorbitan fatty acid esters and 2 to 10% by weight of
oxypropylenated/oxyethylenated C12-C20-fatty alcohols, based on the total
amount of
surface-active substance.
The optimum amount of surface-active substance is influenced firstly by the
surface-
active substance itself, secondly by the reaction temperature, the desired
microcapsule
size and the wall materials. The optimally required amount can be determined
easily
through simple experimental series. As a rule, the surface-active substance is
used for
preparing the emulsion in an amount of from 0.01 to 10% by weight, preferably
0.05 to
5% by weight and in particular 0.1 to 3% by weight, based on the hydrophobic
phase.
Polymerization initiators which can be used are all compounds which
disintegrate into
free radicals under the polymerization conditions, e.g. peroxides,
hydroperoxides,
persulfates, azo compounds and the so-called redox initiators.
In some cases, it is advantageous to use mixtures of different polymerization
initiators,
e.g. mixtures of hydrogen peroxide and sodium or potassium peroxodisulfate.
Mixtures
PF 72435 CA 02856785 2014-05-23
13
of hydrogen peroxide and sodium peroxodisulfate can be used in any desired
ratio.
Suitable organic peroxides are, for example, acetylacetone peroxide, methyl
ethyl
ketone peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, tert-amyl
perpivalate, tert-butyl perpivalate, tert-butyl perneohexanoate, tert-butyl
perisobutyrate,
tert-butyl per-2-ethylhexanoate, tert-butyl perisononanoate, tert-butyl
permaleate, tert-
butyl perbenzoate, tert-butyl per-3,5,5-trimethylhexanoate and tert-amyl
perneodecanoate. Further suitable polymerization initiators are azo starters,
e.g. 2,2'-
azobis-(2-amidinopropane) dihydrochloride, 2,2'-azobis(N,N-
dimethylene)isobutyramidine dihydrochloride, 2-(carbamoylazo)isobutyronitrile
and
4,4'-azobis(4-cyanovaleric acid),
Preference is given to using azo starters and peroxides as polymerization
initiators.
The specified polymerization initiators are used in customary amounts, e.g. in
amounts
of from 0.1 to 5, preferably 0,1 to 2.5 mol%, based on the monomers to be
polymerized.
The dispersion of the core material takes place in a known manner according to
the
size of the capsules to be produced. For producing large capsules, dispersion
using
effective stirrers, in particular anchor stirrers and MIG (cross-arm) stirrers
suffices.
Small capsules, particularly if the size is to be below 50 pm, require
homogenization
and dispersion machines.
The capsule size can be controlled within certain limits via the rotational
speed of the
dispersing device/homogenizing device and/or with the help of the
concentration of the
surface-active substance and/or via its molecular weight, i.e. via the
viscosity of the
continuous phase. Here, as the rotational speed increases up to a limiting
rotational
speed, the size of the dispersed particles decreases.
In this connection, it is important that the dispersing devices are used at
the start of
capsule formation. In the case of continuously operating devices with forced
flow, it is
advantageous to send the emulsion several times through the shear field.
As a rule, the polymerization is carried out at 20 to 100 C, preferably at 40
to 95 C.
The polymerization is expediently carried out at atmospheric pressure,
although it is
also possible to work at reduced or slightly increased pressure, e.g. in the
case of a
polymerization temperature above 100 C, thus for example in the range from 0.5
to 5
bar.
The reaction times of the polymerization are normally 1 to 10 hours, in most
cases 2 to
5 hours.
PF 72435 CA 02856785 2014-05-23
14
By means of the method according to the invention it is possible to produce
microcapsule dispersions with a content of from 5 to 40% by weight of
microcapsules.
The microcapsules are individual capsules. By means of suitable conditions
during the
dispersion, capsules with an average particle size in the range from 0.5 up to
100 pm
can be produced. Preference is given to capsules with an average particle size
of from
0.5 to 50 pm, in particular up to 20 pm.
The method according to the invention permits the production of microcapsules
with a
hydrophilic capsule core and a capsule wall made of a polymer based on
(meth)acrylic
acid esters. The capsules according to the invention can be used in a very
wide variety
of fields depending on the core material. In this way, it is possible to
convert hydrophilic
liquids or mixtures of organic acids or salts thereof, inorganic acids,
inorganic bases,
salts of inorganic acids, water-soluble dyes, flavorings, pharmaceutical
active
ingredients, fertilizers, crop protection active ingredients or cosmetic
active ingredients
into a solid formulation and/or oil-dispersible formulation which releases
these as
required.
Thus, microcapsules with a water core are suitable as pore formers for
concrete. A
further application in construction materials is the use of encapsulated water-
soluble
catalysts in binding construction materials.
Microcapsules with encapsulated inorganic or organic acids can advantageously
be
used as boring auxiliaries for, for example, geothermal bores since they
permit a
release only at the bore site. For example, they permit the increase in the
permeability
of underground, carbonatic mineral oil- and/or natural gas-carrying and/or
hydrothermal
rock formations and for the dissolving of carbonatic and/or carbonate-
containing
impurities during the recovery of mineral oil and/or natural gas or the
production of
energy by hydrothermal geothermy by injecting a formulation comprising
microcapsules
according to the invention with encapsulated inorganic or organic acids
through at least
one bore into the rock formation. In addition, encapsulated acids, which
afterall permit
a delayed or targeted release of the acid, are also suitable as catalysts for
producing
chipboard.
Furthermore, the microcapsule dispersion according to the invention with water-
soluble
bleaches or enzymes as core material permits use in detergents and cleaners,
especially in liquid formulations. Consequently, the present invention also
provides the
use of the microcapsules dispersion in detergents for textiles and cleaners
for non-
textile surfaces.
Furthermore, active ingredients which are to be released in a controlled
manner,
whether medical active ingredients, cosmetic active ingredients or else crop
protection
PF 72435 CA 02856785 2014-05-23
active ingredients, can be prepared such that release takes place over an
extended
period as a result of the tightness of the capsule wall.
5 Examples
Example 1
Oil phase:
495.42 g Miglyol 812(decanoyl/octanoyl glyceride fatty acid ester; I-
101s)
10 4.55 g Arlacel P 135 (PEG-30 dipolyhydroxystearate, Atlas Chemie)
1.19 g Cremophor A 6 [75% by weight ceteareth-6 (ethoxylated cetyl
alcohol)]
1.19 g Span 80 (sorbitan monooleate)
4.55 g Span 85 (sorbitan trioleate)
12.00 g methyl methacrylate
15 8.00 g 1,4-butanediol diacrylate
Feed 1
160.00 g water (core material)
20.00 g N-maltoyl-N-methylmethacrylamide
Feed 2
1.33 g of a 75% strength by weight aqueous solution of tert-butyl
perpivalate
The oil phase was introduced as initial charge, feed 1 was added and the
mixture was
dispersed for 30 minutes using a high-speed dissolver stirrer (disk diameter 5
cm) at
5000 rpm. Feed 2 was then added. The emulsion was heated to 60 C with stirring
using an anchor stirrer in 60 minutes. Over 120 minutes, the temperature was
increased to 70 C and heated to 85 C over a further 30 minutes. The mixture
was then
stirred for 120 minutes at this temperature. It was then cooled to room
temperature.
An oil-based microcapsule dispersion with an average particle size D [4,3] of
< 1 pm
was obtained. The wall thickness of the microcapsules was 20% by weight and
the
solids content of the microcapsule dispersion was 30% by weight.
Example 2
Oil phase:
495.42 g diisopropylnaphthalene
4.55 g Arlacel P 135
1.19g Cremophor A 6
1.19g Span 80
4.55g Span 85
12.00 g methyl methacrylate (MMA)
8.00 g 1,4-butanediol diacrylate (BDDA)
PF 72435 CA 02856785 2014-05-23
16
Feed 1:
100.00 g water (core material)
60.00 g maleic acid
20.00 g N-allylgluconamide
Feed 2:
1.33 g of a 75% strength by weight aqueous solution of tert-butyl
perpivalate
The oil phase was introduced as initial charge, feed 1 was added and the
mixture was
dispersed for 30 minutes using a high-speed dissolver stirrer (disk diameter 5
cm) at
5000 rpm. Feed 2 was added. The emulsion was heated to 60 C with stirring
using an
anchor stirrer over the course of 60 minutes. Over 120 minutes, the
temperature was
increased to 70 C and heated to 85 C over a further 30 minutes. The mixture
was then
stirred for 120 minutes at this temperature. It was then cooled to room
temperature.
An oil-based microcapsule dispersion with an average particle size D [4,3] of
< 1 pm
was obtained. The wall thickness of the microcapsules was 20% by weight. The
solids
content of the microcapsule dispersion was 30% by weight.
Example 3
Oil phase:
608.77 g diisopropylnaphthalene
10.00 g AtIoxo 4912
12.50 g methyl methacrylate (MMA)
Feed 1:
225.00 g water
7.73 g of a 97% strength aqueous solution of 2-hydroxyethyl methacrylate
(HEMA)
1.00 g sodium peroxodisulfate
5.00 g of a Cm/i8 fatty alcohol polyglycol ether (Lutensol AT 25)
The oil phase was introduced as initial charge at 40 C, feed 1 was added and
the
mixture was stirred for 30 minutes using a high-speed dissolver stirrer (disk
diameter
5cm) at 3000 rpm. Feed 2 was added. The emulsion was heated to 60 C with
stirring
using an anchor stirrer over the course of 60 minutes. Over 120 minutes, the
temperature was increased to 70 C and heated to 85 C over the course of a
further 30
minutes. The mixture was then stirred for 120 minutes at this temperature. It
was then
cooled to room temperature.
PF 72435 CA 02856785 2014-05-23
17
An oil-based microcapsules dispersion with an average particle size D [4,3] of
< 1 pm
was obtained. The wall thickness of the microcapsules was 7.75% by weight and
the
solids content of the microcapsules dispersion was 30% by weight.
Example 4
Oil phase:
608.69 g diisopropylnaphthalene
5.00 g Atlox 4912
15.00 g methyl methacrylate (MMA)
Feed 1:
225.00 g water
10.31 g of a 97% strength by weight aqueous solution of 2-hydroxyethyl
methacrylate (HEMA)
1.00 g sodium peroxodisulfate
The oil phase was introduced as initial charge, feed 1 was added and the
mixture was
dispersed for 20 minutes using a high-speed dissolver stirrer (disk diameter 5
cm) at
3000 rpm. The emulsion was heated to 60 C with stirring using an anchor
stirrer over
the course of 60 minutes. Over 120 minutes, the temperature was increased to
70 C
and heated to 85 C over a further 30 minutes. The mixture was then stirred for
120
minutes at this temperature. It was then cooled to room temperature.
An oil-based microcapsule dispersion with an average particle size D [4,3] of
< 1 pm
was obtained. The wall thickness of the microcapsules was 10% by weight, based
on
wall and core. The solids content of the microcapsules dispersion was 30% by
weight.
Example 5
Oil phase:
453.68 g diisopropylnaphthalene
1.50g Atlox 4912
18.00 g methyl methacrylate (MMA)
Feed 1:
270.00 g water
12.37 g of a 97% strength by weight aqueous solution of 2-hydroxyethyl
methacrylate (HEMA)
1.20 g sodium peroxodisulfate
The oil phase was introduced as initial charge, feed 1 was added and the
mixture was
dispersed for 10 minutes using a high-speed dissolver stirrer (disk diameter 5
cm) at
2000 rpm. The emulsion was heated to 60 C with stirring using an anchor
stirrer in 60
PF 72435 CA 02856785 2014-05-23
18
minutes. Over 120 minutes, the temperature was increased to 70 C and heated to
85 C over a further 30 minutes. The mixture was then stirred for 120 minutes
at this
temperature. It was then cooled to room temperature. The wall thickness of the
microcapsules was 10% by weight of the microcapsules. The solids content of
the
microcapsule dispersion was 40% by weight.
Example 6
Oil phase:
800.00 g diisopropylnaphthalene
8.00 g Atlox 4912
Feed 1:
205.70 g of a 35% strength sodium silicate solution in water
154.30g water
Feed 2:
34.00 g methyl methacrylate (MMA)
4.00 g 1,4-butanediol diacrylate
2.00 g 2-hydroxyethyl methacrylate
Feed 3:
0.15 g Wako V 50 [2,2"-azobis(2-amidinopropane) dihydrochloride]
Feed 4:
0.15 g Wako V 65 [2,2"-azobis(2,4-dimethylvaleronitrile)]
The oil phase was introduced as initial charge, feed 3 was dissolved in feed
1, and
feeds 1 and 2 were added to the oil phase. The mixture was dispersed for 20
minutes
using a high-speed dissolver stirrer (disk diameter 5 cm) at 2000 rpm and then
feed 4
was added. The emulsion was heated to 67 C with stirring using an anchor
stirrer over
the course of 60 minutes and to 75 C over a further 60 minutes. The mixture
was then
stirred for 180 minutes at this temperature. It was then cooled to room
temperature.
The wall thickness of the microcapsules was 10% by weight of the
microcapsules. The
solids content of the microcapsule dispersion was 34% by weight.
Example 7
Analogously to example 2, in place of the mixture of maleic acid and water,
instead a
mixture of 70.59 g of phosphoric acid and 89.41 g of water was encapsulated.
The wall thickness of the microcapsules was 20% by weight of the
microcapsules. The
solids content of the microcapsule dispersion was 30% by weight.
PF 72435 CA 02856785 2014-05-23
19
Example 8
Analogously to example 2, in place of the mixture of maleic acid and water,
instead
60.00 g of catechol were encapsulated with 100.00 g of water.
The wall thickness of the microcapsules was 20% by weight of the
microcapsules. The
solids content of the microcapsule dispersion was 30% by weight.
Example 9
Analogously to example 3, a microcapsule dispersion was prepared, where the
oil
phase used was a mixture of
597.10 g diisopropylnaphthalene
5.00 g AtIox 4912
12.50 g methyl methacrylate (MMA).
The wall thickness of the microcapsules was 7.75% by weight of the
microcapsules.
The solids content of the microcapsule dispersion was 30% by weight.
Example 10
Analogously to example 4, a microcapsule dispersion was prepared, a mixture of
225.00 g water
10.00 g 2-hydroxyethyl acrylate
1.00 g sodium peroxodisulfate
being used as feed 1.
The wall thickness of the microcapsules was 10% by weight of the
microcapsules. The
solids content of the microcapsule dispersion was 29.6% by weight.
Example 11
Analogously to example 4, a microcapsule dispersion was prepared, where the
oil
phase had the following composition.
Oil phase:
588.27 g diisopropylnaphthalene
1.25g Atlox 4912
10.00 g methyl methacrylate (MMA)
5.00 g 1,4-butanediol diacrylate
The wall thickness of the microcapsules was 10% by weight of the
microcapsules. The
solids content of the microcapsule dispersion was 30% by weight.
Example 12
Oil phase:
495.42 g diisopropylnaphthalene
4.55g Arlacel P 135
1.19g Cremophor A 6
1.19g Span 80
PF 72436 CA 02856785 2014-05-23
4.55g Span 85
12.00 g methyl methacrylate (MMA)
8.009 1,4-butanediol diacrylate (BDDA)
5 Feed 1:
89.41 g water (core material)
70.59 g phosphoric acid
20.00 g 1-methacrylamido-2-D-gluconoylaminoethane
10 Feed 2:
1.33 g of a 75% strength by weight aqueous solution of tert-butyl
perpivalate
The oil phase was introduced as initial charge, feed 1 was added and the
mixture was
dispersed for 30 minutes using a high-speed dissolver stirrer (disk diameter 5
cm) at
15 5000 rpm. Feed 2 was added. The emulsion was heated to 60 C with
stirring using an
anchor stirrer over the course of 60 minutes. Over 120 minutes, the
temperature was
increased to 70 C and heated to 85 C over a further 30 minutes. The mixture
was then
stirred for 120 minutes at this temperature. It was then cooled to room
temperature.
An oil-based microcapsule dispersion with an average particle size D [4,3] of
< 1 pm
20 was obtained. The wall thickness of the microcapsules was 20% by weight.
The solids
content of the microcapsule dispersion was 30% by weight.
Example 13
Analogously to example 4, but with 1.00 g of Wako V50 instead of sodium
peroxodisulfate and with the oil phase described in example 11, a microcapsule
dispersion was prepared.
The wall thickness of the microcapsules was 10% by weight of the
microcapsules. The
solids content of the microcapsule dispersion was 30% by weight.
Example 14
Oil phase:
588.27 g diisopropylnaphthalene
1.25g Atlox 4912
7.50 g methyl methacrylate (MMA)
10.00 g tert-butyl acrylate
Feed 1:
225.00 g water
7.73 g of a 97% strength by weight aqueous solution of 2-hydroxyethyl
methacrylate (HEMA)
1.00 g Wako V 50
PF 72435 CA 02856785 2014-05-23
21
The oil phase was introduced as initial charge, feed 1 was added and the
mixture was
dispersed for 10 minutes using a high-speed dissolver stirrer (disk diameter 5
cm) at
2000 rpm. The emulsion was heated to 60 C with stirring using an anchor
stirrer over
the course of 60 minutes. Over 120 minutes, the temperature was increased to
70 C
and heated to 85 C over a further 30 minutes. The mixture was then stirred for
120
minutes at this temperature. It was then cooled to room temperature.
An oil-based microcapsule dispersion with an average particle size D [4,3] of
< 1 pm
was obtained. The wall thickness of the microcapsules was 10% by weight, based
on
wall and core. The solids content of the microcapsule dispersion was 30% by
weight.
Example 15
Analogously to example 14, in place of 10.00 g of tert-butyl acrylate, 10.00 g
of glycidyl
methacrylate were used.
The wall thickness of the microcapsules was 10% by weight and the solids
content of
the microcapsule dispersion was 30% by weight.
US Provisional Patent Application No. 61/577105, filed on December 19, 2011,
is
included in the present application by literature reference.
