Reaction products of amine and a carboxyl functional microgel

Reaction products of a microgel that contains carboxylic acid groups with a nitrogen-containing base have a high latency and high stability towards mechanical influences and are suitable as hardeners for one-component epoxy resin systems.

The present invention relates to a reaction product of a microgel that 
contains carboxylic acid groups with a nitrogen-containing base (microgel 
amine salt or microgel imidazole salt), to a process for the preparation 
of such a reaction product, to a composition comprising such a reaction 
product and an epoxy resin, and also to cross-linked products obtainable 
by curing that composition. 
Nitrogen-containing bases are well known to the person skilled in the art 
as hardeners or curing-accelerators for epoxy resins. However, such 
systems have only limited storage stability, since the bases react with 
epoxides even at relatively low temperature, in some cases even at room 
temperature, which manifests itself in an increase in the viscosity of the 
epoxy resin formulation and, in the case of a prolonged period of storage, 
results in gelling of the mixture. Increasing reactivity of the 
nitrogen-containing base reduces the storage stability of the epoxy resin 
mixture and shortens the usable life (pot life). For that reason, such 
systems are formulated in the form of two-component systems, that is to 
say the epoxy resin and the nitrogen-containing base are stored separately 
and are mixed together only shortly before processing. 
Attempts have been made to improve the storage stability of such systems by 
developing curing systems that have a high latency. High latency means 
high stability at the storage temperature in question without there being 
any substantial reduction in the reactivity at the desired curing 
temperature. 
EP-A-304 503 describes master batches comprising encapsulated materials and 
epoxides as latent hardeners for epoxy resins, the core material being a 
tertiary amine in the form of a powder, which is surrounded by a shell 
comprising a reaction product of the same amine with an epoxy resin. 
A similar curing system, but having a core material comprising an amine and 
an anhydride, is disclosed in JP-A-Hei 02-191624. 
Although such latent hardeners or accelerators based on encapsulated 
particles are suitable for the preparation of one-component systems that 
are stable to storage, they have the disadvantage of insufficient 
stability towards mechanical influences, such as, for example, shearing 
forces and compressive loads. 
The problem underlying the present invention is to provide latent epoxy 
curing systems having an improved pot life that also have higher stability 
towards mechanical stress in the form of shearing forces. 
It has now been found that salts of microgels that contain COOH groups with 
nitrogen bases have the required property profile. 
The present invention relates to a reaction product of a microgel that 
contains carboxylic acid groups with a nitrogen-containing base. 
Generally, microgels are understood to mean macromolecules, the chain 
segments of which are cross-linked in the region of the individual 
agglomerates by covalent bridges. Microgels can be prepared in accordance 
with various known polymerisation methods. An advantageous method is the 
emulsion polymerisation of compounds having polymerisable C--C double 
bonds in the presence of so-called multifunctional cross-linkers, for 
example in accordance with the seeding technique. In that technique, after 
the polymerisation the microgel particles are in the form of an aqueous 
emulsion or suspension. The further reaction with the nitrogen-containing 
base can be carried out preferably using such an emulsion/suspension. It 
is, however, also possible first to isolate the microgel in the form of a 
solid powder, for example by means of spray-drying or freeze-drying, or to 
convert the aqueous emulsion into an organic phase by solvent exchange. 
In principle, any compounds containing at least two polymerisable C--C 
double bonds may be used as multifunctional cross-linkers. 
Intramolecularly cross-linked copolymers are formed, which generally have 
particle sizes in the nanometer range (approximately from 5 to 1000 nm). 
A preferred microgel for the preparation of the reaction product according 
to the invention is a copolymer of at least one unsaturated carboxylic 
acid and at least one multifunctional cross-linker. 
An especially preferred microgel is a copolymer of at least one unsaturated 
carboxylic acid, at least one vinyl monomer that contains no carboxylic 
acid groups and at least one multifunctional cross-linker. 
In principle, any carboxylic acids that contain a polymerisable C--C double 
bond are suitable for the preparation of microgels that contain carboxylic 
acid groups. 
Preferred unsaturated carboxylic acids are acrylic acid, methacrylic acid, 
2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, phthalic acid 
mono(2-acryloylethyl) ester, phthalic acid mono(2-methacryloylethyl) 
ester, maleic acid, maleic acid monomethyl ester, maleic acid monoethyl 
ester, fumaric acid, fumaric acid monomethyl ester, fumaric acid monoethyl 
ester, itaconic acid, cinnamic acid, crotonic acid, 
4-vinylcyclohexanecarboxylic acid, 4-vinylphenylacetic acid and 
p-vinylbenzoic acid. 
Acrylic acid and methacrylic acid are especially preferred. 
In principle, any compounds containing at least two polymerisable C--C 
double bonds are suitable as multifunctional cross-linkers. Also suitable 
as multifunctional cross-linkers are mixtures of at least two vinyl 
monomers, for example methacrylic acid and glycidyl methacrylate, that are 
capable of reacting with one another by way of additional functional 
groups during or after the polymerisation reaction. 
As a multifunctional cross-linker it is preferred to use a polyfunctional 
acrylic acid ester or methacrylic acid ester of an aliphatic, 
cycloaliphatic or aromatic polyol, an addition product of acrylic acid or 
methacrylic acid and a polyglycidyl compound, an addition product of 
acrylic acid or methacrylic acid and glycidyl acrylate or methacrylate, an 
acrylic acid alkenyl ester or methacrylic acid alkenyl ester, a 
dialkenylcyclohexane or a dialkenylbenzene. 
Especially preferred multifunctional cross-linkers are ethylene glycol 
diacrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, 
propylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol 
dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol 
dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol 
dimethacrylate, 1,1,1-trimethylolpropane triacrylate, 
1,1,1-trimethylolpropane trimethacrylate, diglycidyl ether diacrylate of 
bisphenol A, diglycidyl ether dimethacrylate of bisphenol A, acrylic acid 
allyl ester, methacrylic acid allyl ester, divinylcyclohexane and 
divinylbenzene. 
The monomer mixture used for the preparation of the microgels may contain 
one or more vinyl monomers that contain no carboxylic acid groups, for 
example butadiene and butadiene derivatives, acrylonitrile, 
methacrylonitrile, acrylic acid esters and amides, methacrylic acid esters 
and amides, vinyl ethers and esters, allyl ethers and esters, styrene and 
styrene derivatives. 
Preferred vinyl monomers that contain no carboxylic acid groups are alkyl 
esters, hydroxyalkyl esters and glycidyl esters of unsaturated carboxylic 
acids, and styrene derivatives. 
Especially preferred vinyl monomers that contain no carboxylic acid groups 
are methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl 
methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, butyl 
acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl 
methacrylate and styrene. 
The reaction product according to the invention is preferably prepared from 
a microgel that is a copolymer of from 2 to 70% by weight of at least one 
unsaturated carboxylic acid, from 0 to 96% by weight of at least one vinyl 
monomer that contains no carboxylic acid groups and from 2 to 70% by 
weight of at least one multifunctional cross-linker, the total of the 
percentages by weight always being 100. 
Especially preferred microgels are copolymers of from 5 to 50% by weight, 
especially from 10 to 40% by weight, of at least one unsaturated 
carboxylic acid, from 0 to 90% by weight, especially from 30 to 85% by 
weight, of at least one vinyl monomer that contains no carboxylic acid 
groups and from 5 to 50% by weight, especially from 5 to 30% by weight, of 
at least one multifunctional cross-linker. 
For simplicity, the reaction products according to the invention are 
referred to hereinafter as "microgel amine salts", the term "amine" in 
this context denoting quite generally "nitrogen-containing bases" and not 
being limited to the meaning of the term "amine" in its stricter sense. 
Suitable nitrogen-containing bases for the preparation of the reaction 
products according to the invention are in principle any basic compounds 
containing at least one basic nitrogen atom. 
Examples thereof are aliphatic, cycloaliphatic and aromatic amines and also 
saturated and unsaturated N-heterocycles. 
Primary, secondary and tertiary amines may be used; it is also possible to 
use compounds having a plurality of basic nitrogen atoms. Examples thereof 
are imidazoles, polyamines, such as triethylenetetramine or 
isophoronediamine, polyaminoamides, for example, the reaction products of 
aliphatic polyamines and dimerised or trimerised fatty acids, and also 
polyoxyalkyleneamines, for example Jeffamine.RTM. (Texaco). 
Preferably an amine, a polyamine or an imidazole is used. 
Mixtures of amines and imidazoles are, of course, also suitable. 
Especially preferred nitrogen-containing bases are the amines and 
imidazoles of formula I, II or III 
NR.sub.1 R.sub.2 R.sub.3 (I), 
R.sub.4 R.sub.5 N--A--NR.sub.6 R.sub.7 (II) 
##STR1## 
wherein R.sub.1 to R.sub.7 are each independently of the others hydrogen, 
C.sub.1 -C.sub.12 alkyl, unsubstituted or substituted phenyl, benzyl, 
phenylethyl, cyclopentyl or cyclohexyl, or R.sub.2 and R.sub.3 or R.sub.4 
and R.sub.5 or R.sub.6 and R.sub.7 together form tetramethylene, 
pentamethylene, --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.2 -- 
--(CH.sub.2).sub.2 --NH--(CH.sub.2).sub.2 --, 
A is C.sub.1 -C.sub.30 alkanediyl, 
R.sub.8 to R.sub.11 are each independently of the others hydrogen, C.sub.1 
-C.sub.18 alkyl, phenyl or benzyl, or 
R.sub.8 and R.sub.9 or R.sub.8 and R.sub.11 or R.sub.10 and R.sub.11 
together form tetramethylene, pentamethylene, --(CH.sub.2).sub.2 
--O--(CH.sub.2).sub.2 -- or --(CH.sub.2).sub.2 --NH--(CH.sub.2).sub.2 --. 
Examples of amines of formula I are trimethylamine, triethylamine, 
phenyldimethylamine, diphenylmethylamine, triphenylamine, benzylamine, 
N,N-dimethylbenzylamine, pyrrolidine, N-methylpyrrolidine, 
N-methylpiperidine and N-phenylpiperidine. 
Suitable diamines of formula II are, for example, 1,2-diaminoethane and 
N,N,N',N'-tetramethyl-1,2-diaminoethane. 
Examples of imidazoles of formula III are imidazole, 1-methylimidazole, 
2-methylimidazole, 2-phenylimidazole, 2-isopropylimidazole, 
2-dodecylimidazole, 2-heptadecylimidazole and 2-ethyl-4-methylimidazole. 
2-Phenylimidazole, 2-isopropylimidazole, 2-dodecylimidazole, 
2-heptadecylimidazole and 2-ethyl-4-methylimidazole are especially 
preferred nitrogen-containing bases. 
The reaction of the nitrogen-containing base with the microgel that 
contains carboxylic acid groups is preferably carried out in solution. 
Preferred solvents are water and mixtures of water and water-miscible 
solvents, for example, methanol, ethanol, isopropanol or acetone. The 
emulsion or suspension produced in the preparation of the microgel by 
emulsion polymerisation can be used directly. The reaction temperatures 
are advantageously from 0.degree. to 200.degree. C., preferably from 10 to 
100.degree. C. The relative proportions of the starting materials can vary 
within wide limits. Advantageously, however, the microgel that contains 
carboxylic acid groups and the nitrogen-containing base are used in 
amounts such that the COOH groups are present in equimolar amounts or in 
excess in relation to basic nitrogen atoms. The number of basic nitrogen 
atoms, based on the number of COOH groups in the microgel, is preferably 
from 5 to 100 mol %, especially from 30 to 100 mol % and more especially 
from 60 to 95 mol %. 
The isolation of the microgel amine salt in the form of a solid powder may 
be carried out by means of spray-drying or lyophilisation. Alternatively, 
however, it is possible to cause the emulsion/suspension to coagulate 
using known methods (addition of electrolyte, freezing out) and to isolate 
the resulting product in the form of a solid substance by filtration, 
which solid substance can be converted, as appropriate, into the desired 
particle size by further pulverisation. It is also possible for the 
product to be obtained by concentrating the emulsion to dryness by 
evaporation and converting the residue into the desired form using known 
methods. 
Depending on the intended use, it is not, however, absolutely necessary to 
isolate the microgel amine salt of the invention in the form of a solid 
substance; it can also be used in the form of an aqueous 
emulsion/suspension or in the form of an emulsion/suspension in an organic 
solvent or in a mixture of more than one organic solvent. 
The invention relates also to a process for the preparation of a reaction 
product according to the invention, which comprises reacting a microgel 
that contains carboxylic acid groups with a nitrogen-containing base at a 
temperature of from 0.degree. C. to 200.degree. C., preferably from 
10.degree. C. to 100.degree. C., the starting materials being used in 
amounts such that the number of carboxylic acid groups is equal to or 
greater than the number of basic nitrogen atoms. 
The process for the preparation of the microgel amine salts according to 
the invention is significantly simpler than the preparation of the 
encapsulated amines according to EP-A-304 503. 
As mentioned at the outset, the microgel amine salts according to the 
invention are suitable especially as hardeners or curing-accelerators for 
epoxy resins. 
The invention accordingly relates also to a composition comprising: 
(a) an epoxy resin having on average more than one 1,2-epoxide group per 
molecule, and 
(b) a reaction product of a microgel that contains carboxylic acid groups 
with a nitrogen-containing base (microgel amine salt). 
Suitable as component (a) for the preparation of the compositions according 
to the invention are the epoxy resins customarily employed in epoxy resin 
technology. Examples of epoxy resins are: 
I) Polyglycidyl and poly(.beta.-methylglycidyl) esters, obtainable by 
reaction of a compound having at least two carboxy groups in the molecule 
with epichlorohydrin or .beta.-methyl-epichlorohydrin, respectively. The 
reaction is advantageously carried out in the presence of bases. 
As compounds having at least two carboxy groups in the molecule there may 
be used aliphatic polycarboxylic acids. Examples of such polycarboxylic 
acids are oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic 
acid, suberic acid, azelaic acid and dimerised or trimerised linoleic 
acid. 
It is also possible, however, to use cycloaliphatic polycarboxylic acids, 
for example tetra-hydrophthalic acid, 4-methyltetrahydrophthalic acid, 
hexahydrophthalic acid and 4-methyl-hexahydrophthalic acid. 
Aromatic polycarboxylic acids may also be used, for example phthalic acid, 
isophthalic acid and terephthalic acid. 
II) Polyglycidyl or poly(.beta.-methylglycidyl) ethers, obtainable by 
reaction of a compound having at least two free alcoholic hydroxy groups 
and/or phenolic hydroxy groups with epichlorohydrin or 
.beta.-methylepichlorohydrin, respectively, under alkaline conditions or 
in the presence of an acid catalyst with subsequent alkaline treatment. 
Such glycidyl ethers are derived, for example, from acyclic alcohols, e.g. 
from ethylene glycol, diethylene glycol or higher poly(oxyethylene) 
glycols, propane-1,2-diol or poly-(oxypropylene) glycols, 
propane-1,3-diol, butane-1,4-diol, poly(oxytetramethylene) glycols, 
pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerol, 
1,1,1-trimethylolpropane, pentaerythritol, sorbitol, and also from 
polyepichlorohydrins. Further such glycidyl ethers are derived from 
cycloaliphatic alcohols, such as 1,4-cyclo-hexanedimethanol, 
bis(4-hydroxycyclohexyl)methane or 2,2-bis(4-hydroxycyclohexyl)propane, or 
from alcohols containing aromatic groups and/or further functional groups, 
such as N,N-bis(2-hydroxyethyl)aniline or 
p,p'-bis(2-hydroxyethylamino)diphenylmethane. 
The glycidyl ethers may be based on mononuclear phenols, for example 
resorcinol or hydroquinone, or on polynuclear phenols, for example 
bis(4-hydroxyphenyl)methane, 4,4'-dihydroxybiphenyl, 
bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 
2,2-bis(4-hydroxyphenyl)propane or 
2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane. Further suitable hydroxy 
compounds for the preparation of glycidyl ethers are novolaks, obtainable 
by condensation of aldehydes, such as formaldehyde, acetaldehyde, chloral 
or furfuraldehyde, with phenols or bisphenols unsubstituted or substituted 
by chlorine atoms or by C.sub.1 -C.sub.9 alkyl groups, for example phenol, 
4-chlorophenol, 2-methylphenol or 4-tert-butyl-phenol. 
III) Poly(N-glycidyl) compounds, obtainable by dehydrochlorination of the 
reaction products of epichlorohydrin with amines that contain at least two 
amine hydrogen atoms. Those amines are, for example, aniline, 
n-butylamine, bis(4-aminophenyl)methane, m-xylylene-diamine or 
bis(4-methylaminophenyl)methane. 
The poly(N-glycidyl) compounds, however, include also triglycidyl 
isocyanurate, N,N'-diglycidyl derivatives of cycloalkyleneureas, such as 
ethyleneurea or 1,3-propyleneurea, and diglycidyl derivatives of 
hydantoins, such as of 5,5-dimethylhydantoin. 
IV) Poly(S-glycidyl) compounds, for example di-S-glycidyl derivatives, 
derived from dithiols, for example ethane-1,2-dithiol or 
bis(4-mercaptomethylphenyl) ether. 
V) Cycloaliphatic epoxy resins, for example bis(2,3-epoxycyclopentyl) 
ether, 2,3-epoxy-cyclopentylglycidyl ether, 
1,2-bis(2,3-epoxycyclopentyloxy)ethane or 
3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate. 
Alternatively, epoxy resins may be used in which the 1,2-epoxide groups are 
bonded to different hetero atoms and/or functional groups; those compounds 
include, for example, the N,N,O-triglycidyl derivative of 4-aminophenol, 
the glycidyl ether-glycidyl ester of salicylic acid, 
N-glycidyl-N'-(2-glycidyloxypropyl)-5,5-dimethylhydantoin and 
2-glycidyloxy-1,3-bis-(5,5-dimethyl-1-glycidylhydantoin-3-yl)propane. 
For the preparation of the epoxy resin compositions according to the 
invention, it is preferred to use a liquid or solid polyglycidyl ether or 
ester, especially a liquid or solid diglycidyl ether of bisphenol or a 
solid or liquid diglycidyl ester of a cycloaliphatic or aromatic 
dicarboxylic acid, or a cycloaliphatic epoxy resin. Mixtures of epoxy 
resins may also be used. 
Suitable solid polyglycidyl ethers and esters are compounds having melting 
points above room temperature up to approximately 250.degree. C. 
Preferably the melting points of the solid compounds are in the range from 
50 to 150.degree. C. Such solid compounds are known and some of them are 
commercially available. As solid polyglycidyl ethers and esters there may 
also be used the advancement products obtained by pre-extension of liquid 
polyglycidyl ethers and esters. 
The epoxy resin compositions according to the invention especially comprise 
a liquid polyglycidyl ether or ester. 
Especially preferred as component (a) are a diglycidyl ether of bisphenol A 
and a diglycidyl ether of bisphenol F. 
The microgel amine salts according to the invention may be used not only as 
hardeners but also as accelerators for curing using other curing agents. 
The present invention accordingly relates also to a composition comprising: 
(a) an epoxy resin having on average more than one 1,2-epoxide group per 
molecule, 
(b) a reaction product of a microgel that contains carboxylic acid groups 
with a nitrogen-containing base (microgel amine salt) and 
(c) a hardener for the epoxy resin (a) that is different from component 
(b). 
Preferred hardeners are polycarboxylic acid anhydrides. 
The anhydrides may be linear aliphatic polymeric anhydrides, for example 
polysebacic acid polyanhydride or polyazelaic acid polyanhydride, or 
cyclic carboxylic acid anhydrides. 
Cyclic carboxylic acid anhydrides are especially preferred. 
Examples of Cyclic Carboxylic Acid Anhydrides are 
succinic acid anhydride, citraconic acid anhydride, itaconic acid 
anhydride, alkenyl-substituted succinic acid anhydrides, dodecenylsuccinic 
acid anhydride, maleic acid anhydride and tricarballylic acid anhydride, 
adduct of maleic acid anhydride with cyclopentadiene or 
methylcyclopentadiene, adduct of linoleic acid with maleic acid anhydride, 
alkylated endoalkylenetetrahydrophthalic acid anhydrides, 
methyltetrahydrophthalic acid anhydride and tetrahydrophthalic acid 
anhydride; the isomeric mixtures of the latter two are especially 
suitable. Also preferred are hexahydrophthalic acid anhydride and 
methylhexahydrophthalic acid anhydride. 
Further examples of cyclic carboxylic acid anhydrides are aromatic 
anhydrides, for example pyromellitic acid dianhydride, trimellitic acid 
anhydride and phthalic acid anhydride. 
Chlorinated or brominated anhydrides, for example tetrachlorophthalic acid 
anhydride, tetrabromophthalic acid anhydride, dichloromaleic acid 
anhydride and chlorendic anhydride, may also be used. 
Also suitable as hardeners are the carboxylic acids, derived from the 
above-mentioned carboxylic acid anhydrides, that have at least two carboxy 
groups per molecule or at least one carboxy group and one anhydride group 
per molecule. A further suitable hardener is dicyandiamide. 
The relative proportions of components (a) and (b) can vary within wide 
limits in the compositions according to the invention. The optimum ratio 
is, inter alia, dependent on the type of amine and on the amine content of 
the microgel amine salt and can be determined readily by the person 
skilled in the art. 
When the microgel amine salt is used as a hardener, the weight ratio of 
components (a):(b) is advantageously from 1:5 to 500:1, preferably from 
1:2 to 200:1 and especially from 1:1 to 100:1. 
When the microgel amine salt is used as an accelerator, substantially 
smaller amounts are effective. The weight ratio of components (a):(b) is 
in that case advantageously from 1:2 to 2000:1, preferably from 1:1 to 
1000:1 and especially from 2:1 to 1000:1. 
The compositions according to the invention may, where appropriate, 
comprise further accelerators, such as imidazoles or benzyldimethylamine. 
Furthermore, the curable mixtures may comprise tougheners, for example 
core/shell polymers or the elastomers or elastomer-containing graft 
polymers that are known to the person skilled in the art as "rubber 
tougheners". 
Suitable tougheners are described, for example, in EP-A-449 776. 
Moreover, the curable mixtures may comprise fillers, such as metal powder, 
wood dust, glass powder, glass beads, semimetal oxides and metal oxides, 
for example SiO.sub.2 (aerosils, quartz, quartz powder, fused silica 
powder), corundum and titanium oxide, semimetal nitrides and metal 
nitrides, such as silicon nitride, boron nitride and aluminum nitride, 
semimetal carbides and metal carbides (SiC), metal carbonates (dolomite, 
chalk, CaCO.sub.3), metal sulfates (barite, gypsum), mineral fillers and 
natural or synthetic minerals mainly from the silicates series, such as 
zeolites (especially molecular sieves) talcum, mica, kaolin, wollastonite, 
bentonite and others. 
In addition to the above-mentioned additives, the curable mixtures may 
comprise further customary adjuvants, for example antioxidants, light 
stabilizers, plasticizers, colorants, pigments, thixotropic agents, 
toughness improvers, antifoams, antistatics, glidants and demoulding 
auxiliaries. 
The compositions according to the invention may be prepared in accordance 
with known methods using known mixing apparatus, for example stirrers, 
kneaders, rollers or dry mixers. In the case of solid epoxy resins, 
dispersing may be carried out also in the melt. The temperature during the 
dispersing is to be so selected that premature curing does not occur 
during the mixing process. The optimum curing conditions are dependent on 
the microgel, on the type and amount of the nitrogen-containing base, on 
the epoxy resin and on the form of dispersing, and can be determined by 
the person skilled in the art in each case using known methods. 
When component (b) is in the form of a solid, the microgel amine salt is 
dispersed in the epoxy resin (a) or in a solution of the epoxy resin (a) 
by known methods, for example by simple stirring or by stirring with the 
aid of glass beads. The operation is advantageously carried out at a 
temperature below the temperature at which the microgel amine salt and the 
epoxy resin start to react. Preferably the operation is carried out at 
temperatures below 60.degree. C. 
When component (b) is in the form of a suspension in water or in a solvent, 
that suspension is first mixed with the epoxy resin. The water or solvent 
is then removed by known methods, for example by distillation or 
freeze-drying. The operation is advantageously carried out at a 
temperature below the temperature at which the microgel amine salt and the 
epoxy resin start to react. Preferably the operation is carried out at 
temperatures below 60.degree. C. 
When component (b) is used as an accelerator, the microgel amine salt may 
also be dispersed in the hardener (c). 
The curing of the epoxy resin compositions according to the invention into 
moulded bodies, coatings or the like is carried out in a manner 
customarily employed in epoxy resin technology, as described, for example, 
in "Handbook of Epoxy Resins", 1967, by H. Lee and K. Neville. 
Because of the high latency of the microgel amine salts according to the 
invention, the curable compositions have high storage stability and a long 
usable life and also high resistance to strong mechanical influences 
(shearing load, compressive load). 
The compositions according to the invention are excellently suitable as 
casting resins, laminating resins, adhesives, compression moulding 
compounds, coating compounds and encasing systems for electrical and 
electronic components, especially as casting resins, laminating resins and 
adhesives.

The present invention relates also to the cross-linked products prepared 
from the compositions according to the invention, such as moulded 
materials, coatings or bonded materials. 
EXAMPLES 
I. Preparation of Microgels that Contain Carboxylic Acid Groups 
Example I.1 
Microgel of Methacrylic Acid, Ethyl Acrylate, Methyl Methacrylate, Ethylene 
Glycol Dimethacrylate and Trimethylolpropane Trimethacrylate 
First, a monomer mixture of 21 g of methacrylic acid, 15 g of ethyl 
acrylate, 12 g of methyl methacrylate, 6 g of ethylene glycol 
dimethacrylate and 6 g of trimethylolpropane trimethacrylate is prepared. 
In a sulfonating flask equipped with a glass anchor stirrer, a thermometer, 
a gas connection and a metering connection, 1.8 g of sodium dodecyl 
sulfate and 320 g of deionised water are stirred under nitrogen (approx. 
200 rev/min) and heated at 65.degree. C. (internal temperature). 6 ml of 
the above monomer mixture and a solution of 0.026 g of ammonium persulfate 
in 20 ml of deionised water are then added. The resulting mixture is 
heated to 70.degree. C. and, after 15 minutes' stirring at 70.degree. C., 
the remainder of the monomer mixture is added in the course of 1 h 45 min. 
After 2 hours' stirring at 70.degree. C., a solution of 0.078 g of 
ammonium persulfate in 2 g of deionised water is added, and the reaction 
mixture is stirred at 70.degree. C. for a further 4 hours. After cooling 
to room temperature, the contents of the reaction vessel are filtered 
through a paper filter. The resulting emulsion has a solids content of 
13.8% and an acid value of 0.60 mol/kg, and can be reacted directly with 
an amine or imidazole to form a microgel amine salt according to the 
invention. 
Example I.2 
Microgel of Methacrylic Acid, Ethyl Acrylate, Methyl Methacrylate, Ethylene 
Glycol Dimethacrylate and Trimethylolpropane Trimethacrylate 
First, a monomer mixture of 57.6 g of methacrylic acid, 48 g of ethyl 
acrylate, 86.4 g of methyl methacrylate, 24 g of ethylene glycol 
dimethacrylate and 24 g of trimethylolpropane trimethacrylate is prepared. 
In a sulfonating flask equipped with a glass anchor stirrer, a thermometer, 
a gas connection and a metering connection, 7.2 g of sodium dodecyl 
sulfate and 1280 g of deionised water are stirred under nitrogen (approx. 
200 rev/min) and heated at 65.degree. C. (internal temperature). 24 ml of 
the above monomer mixture and a solution of 0.104 g of ammonium persulfate 
in 80 ml of deionised water are then added. The resulting mixture is 
heated to 70.degree. C. and, after 15 minutes' stirring at 70.degree. C., 
the remainder of the monomer mixture is added in the course of 
approximately 2 hours. After 2 hours' stirring at 70.degree. C., a 
solution of 0.312 g of ammonium persulfate in 8 g of deionised water is 
added, and the reaction mixture is stirred at 70.degree. C. for a further 
6 hours. After cooling to room temperature, the contents of the reaction 
vessel are filtered through a paper filter. The resulting emulsion has a 
solids content of 14.2% and an acid value of 0.45 mol/kg, and can be 
reacted directly with an amine or imidazole to form a microgel amine salt 
according to the invention. 
Example I.3 
Microgel of Methacrylic Acid, Methyl Methacrylate, Ethylene Glycol 
Dimethacrylate and Trimethylolpropane Trimethacrylate 
First, a monomer mixture of 14.4 g of methacrylic acid, 33.6 g of methyl 
methacrylate, 6 g of ethylene glycol dimethacrylate and 6 g of 
trimethylolpropane trimethacrylate is prepared. 
In a sulfonating flask equipped with a glass anchor stirrer, a thermometer, 
a gas connection and a metering connection, 1.8 g of sodium dodecyl 
sulfate and 320 g of deionised water are stirred under nitrogen (approx. 
200 rev/min) and heated at 65.degree. C. (internal temperature). 6 ml of 
the above monomer mixture and a solution of 0.026 g of ammonium persulfate 
in 20 ml of deionised water are then added. The resulting mixture is 
heated to 70.degree. C. and, after 15 minutes' stirring at 70.degree. C., 
the remainder of the monomer mixture is added in the course of approx. 1 
hour. After 2 hours' stirring at 70.degree. C., a solution of 0.026 g of 
ammonium persulfate in 2 g of deionised water is added, and the reaction 
mixture is stirred at 70.degree. C. for a further 6 hours. After cooling 
to room temperature, the contents of the reaction vessel are filtered 
through a paper filter. The resulting emulsion has a solids content of 
14.0% and an acid value of 0.41 mol/kg, and can be reacted directly with 
an amine or imidazole to form a microgel amine salt according to the 
invention. 
Example I.4 
Microgel of Methacrylic Acid, Methyl Methacrylate, Ethylene Glycol 
Dimethacrylate, Trimethylolpropane Trimethacrylate and Silicone Diacrylate 
First, there is prepared a monomer mixture of 15.66 g of methacrylic acid, 
38.82 g of methyl methacrylate, 6.47 g of ethylene glycol dimethacrylate, 
6.47 g of trimethylolpropane trimethacrylate and 0.68 g of silicone 
diacrylate (Ebecryl.RTM. 350 (Radcure Specialties)) and an initiator 
solution of 0.1 g of sodium persulfate in 10 g of deionised water. 
In a sulfonating flask equipped with a glass anchor stirrer, a thermometer, 
a gas connection and a metering connection, 2.07 g of sodium dodecyl 
sulfate and 388 g of deionised water are stirred under nitrogen (approx. 
200 rev/min) and heated at 60.degree. C. (internal temperature). 6.8 ml of 
the above monomer mixture and 3 ml of the initiator solution are then 
added. The resulting mixture is heated to 65.degree. C. and, after 15 
minutes' stirring at 65.degree. C., the remainder of the monomer mixture 
is added in the course of approximately 1 hour. After 2 hours' stirring at 
65.degree. C., 1 ml of the initiator solution is added and, after a 
further 3 hours, a further 2 ml of the initiator solution are added. The 
reaction mixture is stirred for a further 2.75 hours at 65.degree. C. 
After cooling to room temperature, the contents of the reaction vessel are 
filtered through a paper filter. The resulting emulsion has a solids 
content of 14.3% and an acid value of 0.402 mol/kg, and can be reacted 
directly with an amine or imidazole to form a microgel amine salt 
according to the invention. 
II. Preparation of Microgel Amine Salts 
Example II.1 
A solution of 5.95 g of 2-ethyl-4-methylimidazole in 110 ml of isopropanol 
is added, with stirring, to 100 g of the aqueous emulsion prepared in 
accordance with Example I.1. The resulting emulsion of a microgel 
imidazole salt (particle size: 180 nm) is spray-dried (inlet temperature: 
132.degree. C., outlet temperature: 72-76.degree. C.). The dried microgel 
imidazole powder has an amine value of 2.55 mol/kg and an acid value of 
2.97 mol/kg. Thermogravimetric analysis (TGA) shows onset of weight loss 
at 182.degree. C. (onset temperature). 
Example II.2 
A solution of 4.63 g of 2-ethyl-4-methylimidazole in 40 g of isopropanol 
and 40 g of deionised water is added, with stirring, to 100 g of the 
aqueous emulsion prepared in accordance with Example I.2. The resulting 
emulsion of a microgel imidazole salt (particle size: approx. 65 nm) is 
spray-dried (inlet temperature: 132.degree. C., outlet temperature: 
62-73.degree. C.). The dried microgel imidazole powder has an amine value 
of 2.05 mol/kg and an acid value of 2.24 mol/kg. TGA shows onset of weight 
loss at 180.degree. C. (onset temperature). 
Example II.3 
A solution of 7.78 g of 2-phenylimidazole in 110 g of isopropanol is added, 
with stirring, to 100 g of the aqueous emulsion prepared in accordance 
with Example I.1. The mixture is stirred at room temperature until the 
precipitate has dissolved. The resulting emulsion of a microgel imidazole 
salt is spray-dried (inlet temperature: 132.degree. C., outlet 
temperature: 62-72.degree. C.). The dried microgel imidazole powder has an 
amine value of 2.30 mol/kg and an acid value of 2.62 mol/kg. TGA shows 
onset of weight loss at 232.degree. C. (onset temperature). 
Example II.4 
A solution of 10.1 g of 1-benzyl-2-methylimidazole in 110 g of isopropanol 
is added, with stirring, to 100 g of the aqueous emulsion prepared in 
accordance with Example I.1. The mixture is stirred at room temperature 
until the precipitate has dissolved. The resulting emulsion of a microgel 
imidazole salt is spray-dried (inlet temperature: 132.degree. C., outlet 
temperature: 59-62.degree. C.). The dried microgel imidazole powder has an 
amine value of 2.13 mol/kg and an acid value of 2.56 mol/kg. 
Example II.5 
A solution of 8.36 g of 2-ethyl-4-methylimidazole in 30 g of isopropanol 
and 30 g of deionised water is added, with stirring, to 200 g of the 
aqueous emulsion prepared in accordance with Example I.3. The resulting 
emulsion of a microgel imidazole salt (particle size: approx. 130 nm) is 
spray-dried (inlet temperature: 132.degree. C., outlet temperature: 
69-72.degree. C.). The dried microgel imidazole powder has an amine value 
of 2.12 mol/kg and an acid value of 2.47 mol/kg. TGA shows onset of weight 
loss at 182.degree. C. (onset temperature). 
Example II.6 
A solution of 8.42 g of 2-ethyl-4-methylimidazole in 20 g of isopropanol is 
added, with stirring, to 100 g of the aqueous emulsion prepared in 
accordance with Example I.4. The resulting emulsion of a microgel 
imidazole salt is spray-dried (inlet temperature: 132.degree. C., outlet 
temperature: 80.degree. C.). The microgel imidazole powder is then dried 
in vacuo (200 Torr, 26 660 Pa) at 45.degree. C. for 8 hours and has an 
amine value of 1.96 mol/kg and an acid value of 2.04 mol/kg. 
III. Application Examples 
Example III.1 
10.46 g of the microgel imidazole powder prepared in accordance with 
Example II.1. are added to 120 g of a liquid epoxy resin mixture of 
diglycidyl ether of bisphenol A and diglycidyl ether of bisphenol F having 
an epoxy value of 5.3 mol/kg, and are dispersed using a Dispermat 
dispersing apparatus with glass beads at 2000 rev/min (&lt;40.degree. C.) for 
30 minutes. 
The resulting mixture has a viscosity of 1560 mPa.cndot.s at 40.degree. C. 
The viscosity doubles after 12.5 days' storage at 40.degree. C. and after 
90 days' storage at room temperature. 
The gelling times measured in dependence on the temperature are given in 
Table 1. 
Example III.2 
Analogously to Example III.1., a mixture of 10 g of the microgel imidazole 
powder prepared in accordance with Example II.2. and 90 g of a liquid 
epoxy resin mixture of diglycidyl ether of bisphenol A and diglycidyl 
ether of bisphenol F having an epoxy value of 5.3 mol/kg is prepared. The 
mixture has a viscosity of 1520 mPa.cndot.s at 40.degree. C. The viscosity 
doubles after 8 days' storage at 40.degree. C. 
The gelling times measured in dependence on the temperature are given in 
Table 1. 
Example III.3 
Analogously to Example III.1., a mixture of 10.63 g of the microgel 
imidazole powder prepared in accordance with Example II.3. and 110 g of a 
liquid epoxy resin mixture of diglycidyl ether of bisphenol A and 
diglycidyl ether of bisphenol F having an epoxy value of 5.3 mol/kg is 
prepared. The mixture has a viscosity of 1190 mPa.cndot.s at 40.degree. C. 
The viscosity doubles after 15 days' storage at 40.degree. C. 
The gelling times measured in dependence on the temperature are given in 
Table 1. 
Example III.4 
Analogously to Example III.1., a mixture of 9.4 g of the microgel imidazole 
powder prepared in accordance with Example II.4. and 90 g of a liquid 
epoxy resin mixture of diglycidyl of bis of bisphenol A and diglycidyl 
ether prepared. The mixture has a viscosity of 1280 mPa.cndot.s at 
40.degree. C. The viscosity doubles after 5 days' storage at 40.degree. C. 
The gelling times measured in dependence on the temperature are given in 
Table 1. 
Example III.5 
20 g of the microgel imidazole powder prepared in accordance with Example 
II.3. are added to 80 g of a liquid epoxy resin mixture (epoxy value: 5.1 
mol/kg), prepared by mixing 91 g of diglycidyl ether of bisphenol A and 9 
g of polypropylene glycol (400) diglycidyl ether, and dispersed using a 
Dispermat dispersing apparatus with glass beads at 2000 rev/min 
(&lt;40.degree. C.) for 30 minutes. 10 g of the resulting mixture are diluted 
with 70 g of a liquid epoxy resin mixture (epoxy value: 5.1 mol/kg), 
prepared by mixing 91 g of diglycidyl ether of bisphenol A and 9 g of 
polypropylene glycol (400) diglycidyl ether, and the mixture is added to 
66 g of methyltetrahydrophthalic acid anhydride. The unfilled 
resin/hardener/accelerator mixture has a viscosity of 150 mPa.cndot.s at 
40.degree. C. The viscosity doubles after 19 hours' storage at 40.degree. 
C. 
60 g of W12 EST quartz powder are added to 40 g of the unfilled 
resin/hardener/accelerator mixture and mixed using a Dispermat dispersing 
apparatus with glass beads at 1000 rev/min (&lt;25.degree. C.). The resulting 
resin/hardener/accelerator mixture filled with quartz powder has a 
viscosity of 8800 mPa.cndot.s at 40.degree. C. The viscosity doubles after 
20 hours' storage at 40.degree. C. 
The gelling times measured in dependence on the temperature are given in 
Table 1. 
Example III.6 
7 g of the microgel imidazole powder prepared in accordance with Example 
II.5. are added to 63 g of a liquid epoxy resin mixture (epoxy value: 5.1 
mol/kg), prepared by mixing 91 g of diglycidyl ether of bisphenol A and 9 
g of polypropylene glycol (400) diglycidyl ether, and dispersed using a 
Dispermat dispersing apparatus with glass beads at 2000 rev/min 
(&lt;40.degree. C.) for 30 minutes. 24 g of the resulting mixture are diluted 
with 56 g of a liquid epoxy resin mixture (epoxy value: 5.1 mol/kg), 
prepared by mixing 91 g of diglycidyl ether of bisphenol A and 9 g of 
polypropylene glycol (400) diglycidyl ether, and the mixture is added to 
66 g of methyltetrahydrophthalic acid anhydride. The unfilled 
resin/hardener/accelerator mixture has a viscosity of 152 mPa .cndot. s at 
40.degree. C. The viscosity doubles after 48 hours' storage at 40.degree. 
C. 
60 g of W12 EST quartz powder are added to 40 g of the unfilled 
resin/hardener/accelerator mixture and mixed using a Dispermat dispersing 
apparatus with glass beads at 1000 rev/min (&lt;25.degree. C.). The resulting 
resin/hardener/accelerator mixture filled with quartz powder has a 
viscosity of 5000 mPa.cndot.s at 40.degree. C. The viscosity doubles after 
46 hours' storage at 40.degree. C. 
The gelling times measured in dependence on the temperature are given in 
Table 1. 
Example III.7 
10.0 g of the microgel imidazole powder prepared in accordance with Example 
II.6. are added to 100 g of a liquid epoxy resin mixture (epoxy value: 5.1 
mol/kg), prepared by mixing 91 g of diglycidyl ether of bisphenol A and 9 
g of polypropylene glycol (400) diglycidyl ether, and dispersed using a 
Dispermat dispersing apparatus with glass beads at 2000 rev/min 
(&lt;40.degree. C.) for 30 minutes. 13.2 g of the resulting composition are 
diluted with 26.8 g of a liquid epoxy resin mixture (epoxy value: 5.1 
mol/kg), prepared by mixing 91 g of diglycidyl ether of bisphenol A and 9 
g of polypropylene glycol (400) diglycidyl ether, and the mixture is added 
to 33 g of methyltetrahydrophthalic acid anhydride. The unfilled 
resin/hardener/accelerator mixture has a viscosity of 145 mPa .cndot. s at 
4000. The viscosity doubles after 85 hours' storage at 40.degree. C. 
The gelling times measured in dependence on the temperature are given in 
Table 
TABLE 1 
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Gelling times [s] at different temperatures 
Example 100.degree. C. 
120.degree. C. 
130.degree. C. 
140.degree. C. 
150.degree. C. 
160.degree. C. 
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III.1. &gt;6000 893 305 150 102 71 
III.2. 4800 295 170 109 77 58 
III.3. 2400 400 258 155 132 83 
III.4. 922 245 161 119 87 68 
III.5. 2520 740 445 270 164 108 
III.6. 4700 793 440 253 154 96 
III.7 4800 943 526 300 182 113 
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