Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
-1-
K-18011/A
Modified enoxy resins
The present invention relates to epoxy resin compositions modified with
tougheners, the
products obtained therefrom by curing, a method for improving the toughness of
epoxy
resins and also novel tougheners.
In the cured state, epoxy resins have in general excellent mechanical and
chemical
properties such as, for example, good heat resistance, hardness, dimensional
stability,
electrical properties and chemical resistance. However, typical epoxy
thermosetting
materials do not meet the requirements imposed on them relating to toughness
and they
tend to be brittle.
Attempts have already been made to improve this deficiency by incorporating
elastomeric
material into epoxy resins. Thus, EP-A 245 018 describes storage-stable,
thermocurable
epoxy resin compositions as adhesives which contain polymers having a rubber-
soft and a
thermoplastic phase as tougheners. Suitable materials are carboxyl-terminated
butadiene/acrylonitrile rubbers, graft polymers, for example
methacrylate/butadiene/
styrene polymers and so-called core/shell polymers which have a soft core and
a hard
shell. The best toughness is obtained by combining carboxyl-terminated
butadiene/acrylonitrile rubber with corelshell polymers. Furthermore, US-A 3
856 883
discloses a method of improving the impact strength and the fatigue properties
in
thermosetting materials, for example epoxy-, carboxyl- or hydroxyl-functional
resins,
melamine/formaldehyde or phenol/formaldehyde resins. In this publication,
core/shell
polymers having a soft acrylate core and a hard shell which has an epoxy,
carboxyl or
hydroxyl functionality, is incorporated into the resin prepolymer and cured at
the same
time.
US-A 4 778 851 furthermore describes an epoxy resin compasition having good
toughness
and heat resistance which contains a discontinuous phase made of graft rubber
particles in
the epoxy resin phase. These particles have a core/shell structure, with an
elastomeric core
which is insoluble in the epoxy resin and a shell which has groups which react
with the
epoxy groups of the resin.
CA 02039404 2001-04-06
30043-104
2
These epoxy :resins having improved toughness do not,
however, always meet the requirements which are imposed today
on casting resin formu_Lations based on epoxy resin, in
particular in electrical engineering.
It has now bE~en found, surprisingly, that adding a
toughener combined with a compound containing two active
hydrogen atoms improve; both the toughness and the other
mechanical properties of an epoxy resin markedly.
The present invention relates to an epoxy resin
composition which comprises
a) at least one epoxy resin containing on average
more than one 1,2-epoxy group per molecule,
b) an anhydride hardener for the epoxy resin a),
c) a toughenE>_r, and
d) a compound containing two active hydrogen atoms
which is capable of reacting with the epoxy resin a).
According to one aspect of the present invention,
there is provided an epoxy resin composition which comprises:
a) at least one epoxy resin containing on average more than one
1,2-epoxy group per molecule, which is liquid or of low
viscosity, b) an anhydn~de hardener for the epoxy resin a), c)
a Core/Shell polymer a~> a toughener, and d) a compound
containing two active hydrogen atoms which is capable of
reacting with the epoxy resin a), which compound is a
hydroxycarboxylic acid, a dicarboxylic acid, or a biphenol,
which is a mononuclear diphenol, dihydroxy
CA 02039404 2001-04-06
30043-104
2a
naphthalene, dihydroxy biphenyl or another binuclear aromatic
compound which has a methylene, isopropylidene, O, S02 or S
bridge and contains two hydroxyl groups bound to the aromatic
nuclei and wherein the benzene rings may also contain halogen
atoms.
According to another aspect of the present invention,
there is provided a cured product which can be obtained by
curing an epoxy resin composition as described herein i.n a
manner which is standard per se.
According to ~~till another aspect of the present
invention, there is provided a process for improving the
toughness of epoxy resins, wherein a combination of a toughener
with a compound d) as described herein is added to an unfilled
or filled epoxy resin/anhydride hardener system.
According to yet another aspect of the invention,
there is provided the i.;,se of the epoxy resin composition as
described herein as a casting resin, laminating resin, moulding
compound, coating compound or as an encapsulating system of
electrical or electronic components.
2 ~ Suitable epox:~.~ resins which can be used according to
the invention are all t~~pes of epoxy resin such as, for
example, those which contain groups of the formula
0
C HC / \C H ,
,..
2 !~
directly bound to oxygen, nitrogen or sulfur atoms, in which
formula either R' and R " ' are each a hydrogen atom, in which
case R " then denotes a hydrogen atom or a methyl group, or R'
CA 02039404 2001-04-06
30043-104
2b
and R' ' ' are together --CHzCH2- or -CH2CHzCH2-, in which case R' '
denotes a hydrogen atom.
As examples of such resins, mention may be made of
polyglycidyl and poly(y--methylglycidyl) esters which can be
obtained by reacting a compound containing two or more
carboxylic acid groups per molecule with epichlorohydri.n,
glycerol dichlorohydrin or ~3-methylepichlorohydrin in the
presence of alkali. Such polyglycidyl esters can be derived
from aliphatic polycarboxylic acids, for example oxalic acid,
-3-
succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic
acid, sebacic
acid or dimerised or trimerised linolic acid, from cycloaliphatic
polycarboxylic acids such
as tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic
acid and
4-methylhexahydrophthalic acid and from aromatic polycarboxylic acids such as
phthalic
acid, isophthalic acid and terephthalic acid.
Other examples are polyglycidyl and poly(-methylglycidyl) ethers which can be
obtained
by reacting a compound containing at least two free alcoholic and/or phenolic
hydroxyl
groups per molecule with the corresponding epichlorohydrin under alkaline
conditions or,
alternatively, in the presence of an acidic catalyst with subsequent alkali
treatment. These
ethers can be prepared with poly(epichlorohydrin) from acyclic alcohols such
as ethylene
glycol, diethylene glycol and higher poly(oxyethylene) glycols, propane-1,2-
diol and
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 and sorbitol, from cycloaliphatic
alcohols such
as resorcitol, quinitol, bis(4-hydroxycyclohexyl)methane,
2,2-bis(4-hydroxycyclohexyl)propane and l,l-bis(hydroxymethyl)-3-cyclohexene
and
from alcohols containing aromatic nuclei such as N,N-bis(2-
hydroxyethyl)aniline and
p,p =bis(2-hydroxyethylamino)diphenylmethane. They can furthermore be prepared
from
mononuclear phenols such as resorcinol and hydroquinone, and also polynuclear
phenols
such as bis(4-hydroxyphenyl)methane, 4,4-dihydroxydiphenyl,
bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane,
2,2-bis(4-hydroxyphenyl)propane (otherwise known as bisphenol A) and
2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, and also from aldehydes such as
formaldehyde, acetaldehyde, chloral and furfural, and novolaks formed with
phenols such
as phenol itself and phenols ring-substituted by chlorine atoms or alkyl
groups containing
up to nine carbon atoms in each case such as 4-chlorophenol, 2-methylphenol
and
4-tert-butylphenol.
Poly(N-glycidyl) compounds include, for example, those which are obtained by
dehydrochlorination of the reaction products of epichlorohydrin with amines
containing at
least two amino hydrogen atoms such as aniline, n-butylamine,
bis(4-aminophenyl)methane. and bis(4-methylaminophenyl)methane, and
triglycidyl
isocyanurate and also N,N'-diglycidyl derivatives of cyclic alkylene ureas
such as
ethylene urea and 1,3-propylene urea, and hydantoins such as 5,5-
dimethylhydantoin.
-4-
Poly(S-glycidyl) compounds are, for example, the di-S-glycidyl derivatives of
dithiols
such as ethane-1,2-dithiol and bis(4-mercaptomethylphenyl) ether.
Examples of epoxy resins containing groups of the formula
O
/ ~
- CH - C - CH
R' R" R"'
in which R' and R"' together denote a -CH2CH2- or a -CHl-CH2-CH2- group are
bis(2,3-epoxycyclopentyl) ether, 2,3-epoxycyclopentyl glycidyl ether,
1,2-bis(2,3-epoxycyclopentyloxy)ethane and 3,4-epoxycyclohexylmethyl
3',4'-epoxycyclohexanecarboxylate.
Also suitable are epoxy resins in which the 1,2-epoxy groups are bound to
hetero atoms of
various kinds, for example the N,N,O-triglycidyl derivative of 4-aminophenol,
the
glycidyl ether/glycidyl ester of salicylic acid or p-hydroxybenzoic acid,
N-glycidyl-N'-((2-glycidyloxypropyl)-5,5-dimethylhydantoin and
2-glycidyloxy-1,3-bis(5,5-dimethyl-1-glycidyl-3-hydantoinyl)propane.
If desired, epoxy resin mixtures can be used.
Preferred are epoxy resins based on bisphenol A, bisphenol F or a cycloolefin,
in
particular those which contain, on average, two 1,2-epoxy groups per molecule.
Very particularly preferred are liquid and low-viscosity epoxy resins.
Expediently the
viscosity at 25°C does not exceed a value of 20,000 mPa~s.
In principle, all anhydrides of difunctional and higher-functional carboxylic
acids, for
example linear aliphatic polymeric anhydrides, for example polysebacic acid
polyanhydride or polyazelaic acid polyanhydride or cyclic carboxylic acid
anhydrides, the
latter being preferred, may be suitable as anhydride hardeners.
Cyclic carboxylic acid anhydrides are preferably an alicyclic monocyclic or
polycyclic
-5-
anhydride, an aromatic anhydride or a chlorinated or brominated anhydride.
Examples of alicyclic monocyclic anhydrides are: succinic anhydride,
citraconic
anhydride, itaconic anhydride, alkenyl-substituted succinic anhydrides,
dodecenylsuccinic
anhydride, malefic anhydride and tricarballylic anhydride.
Examples of alicyclic polycyclic anhydrides are: malefic anhydride adduct of
methylcyclopentadiene, linolic acid adduct of malefic anhydride, alkylated
endoalkylenetetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride,
tetrahydrophthalic anhydride, the isomer mixtures of the last two being
particularly
suitable. Also preferred is hexahydrophthalic anhydride.
Examples of aromatic anhydrides are: pyromellitic dianhydride, trirnellitic
anhydride and
phthalic anhydride.
Examples of chlorinated or brominated anhydrides are: tetrachlorophthalic
anhydride,
tetrabromophthalic anhydride, dichloromaleic anhydride and chlorendic
anhydride.
Preferably, liquid or readily melting dicarboxylic acid anhydrides are used in
the
compositions according to the invention.
Preferred are compositions containing an alicyclic single-ring or multi-ring
anhydride, in
particular Nadic Methyl Anhydride, hexahydrophthalic anhydride,
methyltetrahydrophthalic anhydride and its isomer mixture.
If desired, the anhydride hardener can be used in combination with a standard
reaction
accelerator for anhydride hardeners. The reaction accelerator can be
incorporated in the
composition simultaneously with the anhydride hardener or, to prolong the
service life,
added to the composition just before curing. Preferably, addition takes place
just shortly
before curing.
Preferably, the anhydride hardener is used in combination with the reaction
accelerator.
Suitable reaction accelerators are, for example, tertiary amines, metal salts
of carboxylic
acids, metal chelates or organophosphines.
-6-
Preferred are the tertiary amines, in particular substiW ted imidazoles, for
example
1-methylimidazole.
Suitable tougheners for the compositions according to the invention are the
elastomers
known to the person skilled in the art as "rubber tougheners" or elastomers
containing
graft polymers, provided they form a second dispersed phase in the epoxy resin
composition according to the invention in the cured state.
At the same time, the tougheners may be liquid or solid in the initial state.
Liquid tougheners form a homogeneous phase in the composition according to the
invention in the uncured state.
Liquid tougheners can also be used as pre-adducts with, for example, epoxy
resins.
Examples of such liquid tougheners are carboxyl-terminated
butadiene/acrylonitrile
copolymers such as those described, for example, in EP-A 245 018.
Solid tougheners include graft polymers such as those described, for example,
in
US-A 3 496 250 and also core/shell polymers such as those disclosed in EP-A 45
357 and
US-A 4 419 496.
Examples of graft polymers are methacrylate/butadiene/styrene,
acrylate/methacrylate/butadiene/styrene or acrylonitrile/butadiene/styrene
polymers.
Core/shell polymers have, as a rule, a soft core made of an elastomeric
material which is
insoluble in the epoxy resin. Grafted on to the latter is a shell of polymeric
material which
may have a functionality which is either reactive or non-reactive with epoxy
groups.
Examples of elastomers which can be used as core material are polybutadiene,
polysulfides, acrylic rubber, butyl rubber or isoprene elastomer. Preferably,
the core
material contains polybutadiene.
Examples of polymeric shell materials are polystyrene, polyacrylonitrile,
methacrylate/acrylic acid copolymers, polymethyl methacrylate or
styrene/acrylonitrile/glycidyl methacrylate copolymers. Preferably polymethyl
_7-
methacrylate is used as the shell material.
The size of such core/shell particles is expediently 0.05-30 um, preferably
0.05-15 wm.
Preferred are core/shell polymers having a shell which is non-reactive with
epoxy groups.
Some of the core/shell polymers, for example Paraloid~ EXL 2607 supplied by
Rohm &
Haas, USA, are commercially available or can be obtained in the way described
in, for
example, US-A 4 419 496 or EP-A 45 357.
Preferably used are core/shell polymers containing a core selected from the
group
comprising polybutadiene, polybutadiene/polystyrene and
polybutadiene/acrylonitrile and
a shell selected from the group comprising polymers based on methyl
methacrylate,
cyclohexyl methacrylate, butyl acrylate, styrene, methacrylonitrile, vinyl
acetate and vinyl
alcohol.
Insofar as the core/shell polymers employed according to the invention are
novel polymer
compositions, they are also a subject of the present invention.
The amount of toughener which is added to the epoxy resin composition
according to the
invention is preferably up to 40% by weight, in particular up to 20% by
weight, based on
the epoxy resin a).
The toughener can also be used in a particularly preferred embodiment as a
suspension in
an epoxy resin.
As compound d), any compound can be used provided it has two active hydrogen
atoms
and is able to react with the epoxy resin a). Preferred compounds d) are those
which are
known to the person skilled in the art as pre-extension compounds for epoxy
resins, for
example biphenols, hydroxycarboxylic acids, dicarboxylic acids, disecondary
amines or
primary amines.
Examples of biphenols are: mononuclear diphenols (such as resorcinol),
naphthalines
containing two hydroicyl groups such as 1,4-dihydroxynaphthalene, biphenyls
and other
binuclear aromatic compounds which have a methylene, isopropylidene, O, S02 or
S
bridge and contain two hydroxyl groups bound to the aromatic nuclei such as,
in
~~~t~fl4
_g_
particular, bisphenol A, bisphenol F or bisphenol S; the benzene rings may
also contain
halogen atoms, such as tetrabromobisphenol A.
Examples of hydroxycarboxylic acids are «-hydroxycarboxylic acids such as
glycolic acid
or lactic acid, S-hydroxycarboxylic acids such as hydracrylic acid or
phenolcarboxylic
acids such as salicylic acid.
Examples of dicarboxylic acids are aliphatic dicarboxylic acids such as oxalic
acid,
malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic
acid or
3,6,9-trioxaundecanedioic acid or aromatic dicarboxylic acids such as phthalic
acid,
isophthalic acid, terephthalic acid or naphthalic acid or diesterdicarboxylic
acids which
can be obtained, for example, by reacting glycols, for example neopentyl
glycol, with two
equivalents of dicarboxylic acid anhydride such as, for example,
tetrahydrophthalic
anhydride.
Examples of disecondary amines which may be either aliphatic or aromatic are
N,N'-diethylethylamine, piperazine or N,N'-dimethylphenylenediamine.
Examples of primary amines are aliphatic amines such as n-propylamine, n-
butylamine,
n-hexylamine or aromatic amines such as aniline or naphthylamine.
Preferred are biphenols, in particular bisphenol A, and dicarboxylic acids, in
particular
3,6,9-trioxaundecanedioic acid.
Expediently up to 50 % by weight, preferably up to 25 % by weight, based on
the epoxy
resin a) of the compound d) is used.
For filled epoxy resin compositions according to the invention, the following
fillers, for
example, are suitable: mineral and fibrous fillers such as quartz powder,
fused quartz,
aluminium oxide, glass powder, mica, kaolin, dolomite, graphite, soot, and
also carbon
fibres and textile fibres. Preferred fillers are quartz powder, fused silica,
aluminium oxide
or dolomite.
The epoxy resin compositions according to the invention are prepared by
methods known
per se, for example with the aid of known mixing units (stirrers, kneaders,
rollers or, in the
case of solid substances or powders, in mills or dry mixers).
-9-
In this connection, it is unimportant whether the toughener is first mixed
separately with
the compound d) and is incorporated as a mixture into the resin/hardener
system or
whether the toughener or the compound d) is added individually, in which case
the
sequence is irrelevant.
Thus, for example, the toughener and the compound d) may be stirred into the
liquid
epoxy resin/anhydride hardener system.
The techniques of incorporation are known and are described, for example, in
US-A 4 778 851.
The epoxy resin compositions according to the invention are cured to form
moulded
bodies or the like at elevated temperature in a manner which is standard per
se for
anhydride hardeners. The curing can be earned out in one, two or more stages,
the first
curing stage being carried out at low temperature and the post-curing at
higher
temperature.
The present invention therefore also relates to the cured products which are
obtainable by
curing the epoxy resin compositions according to the invention in a manner
which is
standard per se.
The present invention also relates to a process for improving the toughness of
epoxy
resins, wherein a combination of a toughener with a compound d) is added to an
unfilled
or filled epoxy resin/anhydride hardener system and the system so obtained is
cured in a
manner which is standard per se.
The epoxy resin compositions according to the invention are eminently suitable
as casting
resins, laminating resins, moulding compounds, coating compounds and also as
encapsulating systems for electrical and electronic components, and in
particular as
casting resins and encapsulating systems for electrical and electronic
components.
Example A: Polymer I
202.7 g of polybutadiene latex (BL 2004 K supplied by Bayer AG) having a
solids content
of 59.2% and 397.3 g of deionised water are introduced under N2 into a 1 I
flask with
plane ground joint fitted with double jacket, glass anchor stirrer,
thermometer, condenser,
- 10-
circulating thermostat and N2 connection and stirred at 100 rpm (revolutions
per minute).
The mixture is heated to 80°C ~ 1 °C. After approximately 55
minutes, an internal
temperature of 80°C has been reached. Now the dropwise addition of 90.0
g of distilled
methyl methacrylate (pure, supplied by Fluka, Switzerland) and a solution of
4.0 g of
potassium peroxydisulfate and 3.5 g of sodium dodecylbenzenesulfonate in 110
ml of
distilled water is started. After 3.5 hours, a homogeneous white emulsion is
obtained.
After a total of 6 hours 10 minutes, the addition of the methyl methacrylate
and of the
initiator is terminated.
Stirring is continued for a further 2 hours at 80°C. At the end of this
time, 3 ml of a 20 %
emulsion of n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxylphenyl)propionate are
added to the
homogeneous white emulsion and the whole is then cooled to room temperature.
At room
temperature the emulsion is also homogeneous and white in colour. It is
filtered through
glass wool. No agglomerates are present. The emulsion is diluted to 900 g,
which results
in a solids content of 22.5 %. The emulsion thus obtained can be used as a
toughener in
two different ways:
- as it is, ie. as a latex (polymer Ia)
- coagulated and ground (polymer Ib).
For the purpose of coagulation, 700 g of the emulsion are heated with 1000 ml
of
deionised water to approximately 70°C while stirring in a 2.51
sulfonation flask. At 68°C,
100 ml of coagulating soh.~tion (100 g of MgS04~7H20 + 850 ml of deionised
water +
50 ml of glacial acetic acid) are added, after which heating is carried out to
90-95°C. At an
internal temperature of 73°C, the emulsion coagulates in very fme form.
As soon as the
internal temperature has reached 90°C, stirring is continued at 90-
95°C for 1 hour. A very
finely divided white suspension is now obtained. This is followed by cooling
to room
temperature, filtering, washing with water and drying in vacuum at 50-
60°C.
157.5 g of white product (96.4 % of theory) are obtained.
Glass transition temperature Tg: -81°C (TMA)
Shore D hardness (DIN 53 505): 51 '
Polymethyl methacrylate (PMMA) effectively grafted on: 71.5 %* (determined by
exhaustive extraction with CHCl3. The homopolymerised PMMA is soluble in this
solvent
and is dissolved out).
-11-
A smaller quantity of the coagulated and worked-up polymer is ground in a ball
mill for
24 hours.
Examples B and C: Polymers II & III
Two further core/shell polymers are synthesised analogously to Example A,
starting from
the same polybutadiene latex BL 20004 K.
The products are the polymers II and III.
Polymer II
Shore D hardness: 61
PMMA grafted on (effectively): 96.4 %*
Polymer III
Shore D hardness: 66
PMMA grafted on (effectively): 146.3 %*
* The values refer to the amount of PMMA (weight) of the shell in relation to
the care.
The polymer II is isolated both in ground form (polymer IIa) and in spray-
dried form
(polymer IIb). In the latter case, the spray-drying is carried out directly
from the emulsion
with the aid of a Biichi~ 190 spray dryer supplied by Biichi, Switzerland, the
inlet
temperature being 104°C and the outlet temperature 69°C.
The polymer III is isolated only in spray-dried form (inlet temperature
104°C, outlet
temperature 67°C).
Example D: Polymer IV
100 g of a solid crystalline epoxy resin based on isocyanurate having an epoxy
content of
9.44 eq/kg are introduced into a 350 ml sulfonation flask having stirrer,
condenser and
thermometer and melted at 120°C. At an internal temperature of
122°C, 100 g of a
carboxyl-terminated butadiene/acrylonitrile copolymer having an H+
equivalent/1944 g
(Hycar~ 1300 x 13 supplied by Goodrich, USA) are weighed out and added to the
flask
directly. At an internal temperature of 131 °C a brown, virtually clear
melt is obtained. The
progress of the reaction is monitored by measuring the epoxy content of the
mixture. The
reaction is continued at an internal temperature of 140°C while
stirring, until a measured
6 k
f'~ ~~ ~ :~
- 12-
epoxy content of 4.41 eq/kg is obtained. With a starting epoxy value of the
mixture of
4.72, this corresponds to a decrease of 0.31 eq/kg (theoretical value 0.26).
The product is
poured off at a temperature of 140°C. Then the product is cooled to
room temperature,
during which process it solidifies.
Example E: Polymers V-XV
The core/shell polymers listed in the table below are synthesised analogously
to Example
A, stauting from the same polybutadiene latex BL 2004 K.
PolymerMonomers % grafting-onShore D
hardness
V Methyl methacrylate/styrene100 57
75:25
VI Methyl methacrylate/glycidyl100 59
methacrylate
75:25
VII Methyl methacrylate/vinyl 100 54
acetate
75:25
VIII Styrene 75 34
IX Vinyl acetate 75 27
X Butyl methacrylate 100 15
XI Butyl acrylate 100 36
XII 2-Ethylhexyl methacrylate 100 6
XIII Methacrylonitrile 100 48
XIV Cyclohexyl methacrylate 100 44
XV Isobutyl methacrylate 100 42
Example F: Suspension of the graft polymer from Example A in an epoxy resin
500 g of a liquid epoxy resin based on bisphenol A having an epoxy content of
5.35 eq/kg
are introduced into a 21 flask with plane ground joint having glass anchor
stirrer and
vacuum connection, and 100 ml of methyl ethyl ketone are added while stirring.
222.2 g of
graft polymer emulsion from Example A having a solids content of 22.5 % (=
50.0 g of
polymer I, 100 % grafting-on) are added to the clear solution so obtained and
stirring is
carried out for 15 min. The homogeneous mixture is heated to approximately
60°C and
evacuated to 150-200 mbar, in which process a methyl ethyl ketone/water
mixture is first
distilled off and then water. Towards the end of the distillation, the
temperature is raised
to 80°C and the pressure lowered to 40-50 mbar, the remaining water
being removed in
the course of 30 min. A homogeneous white suspension which is readily
stirrable at 80°C
is obtained and is poured off after cooling to 50°C.
Yield: 546.2 g
~~~4~~
-13-
Epoxy content: 4.86 eq/kg
Water content: 0.16 % (determined by K. Fischer method)
Toughener content: 10 phr (based on the epoxy resin)
Example G
120 g (100 %) of methyl methacrylate are grafted on to 342.9 g of the
polybutadiene/acrylonitrile latex Europrene~ 2620 (acrylonitrile content 35 %)
having a
solids content of 35.0 % analogously to Example A.
Yield: 967 g of latex
Graft polymer content of the latex: 24.6 %
Shore D hardness (graft polymer): 62
The latex obtained is processed with a liquid epoxy resin based on bisphenol
A, epoxy
content 5.35 eq/kg analogously to Example F to produce a suspension.
Yield: 547 g
Epoxy content: 4.86 eq/kg
.Water content: 0.11 % (determined by K. Fischer method)
Toughener content: 10 phr (based on the epoxy resin)
Example H:
120 g (100 %) of methyl methacrylate are grafted on to 300 g of the
polybutadiene/styrene
latex Intex~ 084 (styrene content 24 %) having a solids content of 40.0
%analogously to
Example A.
Yield: 961 g of latex
Graft polymer content of the latex: 24.7 %
Shore D hardness (graft polymer): 62
The latex obtained is processed with a liquid epoxy resin based on bisphenol
A, epoxy
content 5.35 eq/kg, analogously to Example F to produce a suspension. '
Yield: 549 g
Epoxy content: 4.86 eq/kg
Water content: 0.07 % (determined by K. Fischer method)
~~v~~l
-14-
Toughener content: 10 phr (based on the epoxy resin)
Example I:
202.7 g of polybutadiene latex Baystal~ 2004 K (solids content 59.2%) are
mixed with
397.2 g of deionised water in a 1.51 flask with plane ground joint having
double jacket,
glass anchor stirrer, thermometer and condenser, and heated to 80°C~
1°C while stirring
(1000 rpm). At 80°C, 23.0 g of hexanediol dimethacrylate (0.15 eq C-C
double
bonds/100 g of polybutadiene) and 30 ml of initiator solution were added in
the course of
1 h. Stirnng of the homogeneous emulsion is then continued for 1 h at
80°C. To determine
the Shore hardness, a sample of the emulsion is coagulated and dried.
Polybutadiene latex 2004 K: Shore A hardness = 41
Additionally crosslinked polybutadiene latex 2004 K: Shore A hardness = 67
Methyl methacrylate (100 %) is then grafted on to the modified (additionally
crosslinked)
polybutadiene analogously to Example A.
Yield: 937 g of latex
Graft polymer content of the latex: 26.9 %
Shore D hardness (graft polymer): 64
The latex obtained is processed with a liquid epoxy resin based on bisphenol
A, epoxy
content 5.3I eq/kg analogously to Example F to produce a suspension.
Yield: 549 g
Epoxy content: 4.83 eq/kg
Water content: 0.13 % (determined by K. Fischer method)
Toughener content: 10 phr (based on the epoxy resin)
Example 1: Methyltetrahydrophthalic anhydride, bisphenol A, a core/shell
toughener
having a PMMA/polybutadiene/styrene coxe and a PMMA shell and having a
particle size
of 0.1-0.3 ~m (Paraloid~ EXL 2607 supplied by Rohm & Haas, USA) and also
1-methylimidazole are added in the amounts shown in Table 1 below to 100 parts
by
weight of a liquid epoxy resin based on bisphenol A having an epoxy content of
5.0-5.25 eq/kg and a viscosity at 25°C of 9000-14 000 mPa~s, and the
mixture is mixed
thoroughly by stirring, the imidazole component only being added to the
mixture at the
a,~~~.~~Q
,.
-15-
end.
Moulded bodies are produced with this mixture which are cured for 6 hours at
$0°C and
then for 10 hours at 140°C and the fracture toughness is then
deternnined.
Table 1
Parts
by
weight
Epoxy resin 1~
Methyltetrahydrophthalic 62
anhydride
Core/shell toughener 16.1
Bisphenol A 16.1
1-Methylimidazole 0.5
Fracture toughness 2032
GIs
(Bend notch) [J/m2]
~~~~~~=x
- 16-
Example 2: The filled epoxy resin system shown in Table 2 is used analogausly
to
Example 1. Curing is carried out for 2 hours at 100°C and then for 10
hours at 140°C.
Table 2
Parts by
weight
Epoxy resin based on bisphenol1~
A,
epoxy eq. 5.0-5.25 kg
Methyltetrahydrophthalic 62
anahydride
Paraloid ~ EXI. 2607 16.1
(Rohm & Haas, USA)
Bisphenol A 16.1
1-Methylimidazole 0.5
Quartz powder W 12 292
Fracture toughness GIs 10I5
(Double torsion) [J/m2]
Impact toughness 15.8
(ISO) [kJ/m2]
Flexural strength 126
(ISO) [N/mm2]
Extreme fibre extension 2.25
(ISO) [%]
r, ~~, ~ l~,
~'~~~'d~
-17-
Example 3: A filled epoxy resin system is used analogously to Example 2, the
resin being
an epoxy resin based on bisphenol A and cycloolefin (69.9 % by weight of
bisphenol A
diglycidyl ether, 29.9 % by weight of 3,4-epoxycyclohexylmethyl
3,4-epoxycyclohexanecarboxylate and 0.2 % by weight of benzyltriethylammonium
chloride) and having an epoxy content of 5.6-6.0 eqlkg and also a viscosity at
25°C of
4200-6500 mPa~s.
The amounts used are shown in Table 3. Curing is carried out for 2 hours at
100°C and
then for 10 hours at 140°C.
Table 3
Parts by
weight
Epoxy resin 1~
Methyltetrahydrophthalic72.2
anhydride
Paraloid ~ EXL 2607 10
Bisphenol A.
18.7
1-Methylimidazole 0.5
Quartz powder W 12 302.1
Fracture toughness GIC 647
(Double torsion) [J/m2]
Impact toughness 10.6
(ISO) [kJ/m2]
Flexural strength 123
(ISO) [N/mm2]
Extreme fibre extension 1.8
(ISO) [%]
-18-
Example 4: 55 parts by weight of the polymer IV from Example D, 25 parts by
weight of
bisphenol A, 80.1 parts by weight of Nadic Methyl Anhydride and 0.5 parts by
weight of
1-methylimidazole are added to 45 parts by weight of a solid epoxy resin based
on
isocyanurate having an epoxy content of 9.3-10.0 eq/kg and mixed.
Curing is carried out fox 10 hours at 80°C, followed by 4 hours at
180°C and 8 hours at
220°C.
The results of the toughness test are shown in Table 4.
Table 4
Example
4
Impact toughness [kJ/m2] 23
Bending angle (to fracture) 51
(<]
Glass transition temperature219
Tg [C]
~~e~~~~ ~~w
- 19-
Example 5: Methyltetrahydrophthalic anhydride and bisphenol A are added to 110
parts
by weight of epoxy resin/graft polymer suspension from Example F at
60°C and mixed.
While stirring vigorously, quartz powder preheated to 140°C is added. 1-
Methylimidazole
is added to the mixture heated to approximately 80°C and the mixture is
stirred
thoroughly. The casting compound is subjected to a vacuum of 5 mbar for 10 min
and then
cast. Curing is carried out for 2 hours at 100°C and then for 10 hours
at I40°C.
The amounts used and the results of the toughness test are shown in Table S.
Table 5
Parts by
weight
Epoxy resin/graft polymer110*
suspension
Methyltetrahydrophthalic62
anhydride
Bisphenol A 18.6
1-Methylimidazole 0.5
Quartz powder W 12 287
Fracture toughness GIs 595
(Double torsion) [J/m2]
Impact toughness 12.9
(ISO) [kJ/m2]
Flexural strength 130
(ISO) [N/mm2]
Extreme fibre extension 2.0
(ISO) [%]
* 10 parts by weight of toughener to 100 parts by weight
of epoxy resin
-20-
Example 6: Instead of bisphenol A as component d) 3,6,9-trioxaundecanedioic
acid is used
analogously to Example 5.
The amounts used and the results of the toughness test are shown in Table 6.
Table 6
Parts by
weight
Epoxy resin/graft polymer110*
suspension
Methyltetrahydrophthalic62
anhydride
3,6,9-Trioxaundecanedioic18.1
acid
1-Methylimidazole 0.5
Quartz powder W 12 286
Fracture toughness GiC 697
(Double torsion) [J/m2]
Impact toughness 12.1
(ISO) (kJ/m2]
Flexural strength 126
(ISO) [N/mm2]
Extreme fibre extension 1.8
(ISO) [%]
* 10 parts by weight of toughener to 100 parts by weight of
epoxy resin
-21-
Example 7: An unfilled epoxy resin system containing the same epoxy resin
based on
bisphenol A and cycloolefin is used analogously to Example 3.
The amounts used and the results of the toughness test are shown in Table 7.
Table 7
Parts by
weight
Epoxy resin 100
Methyltetrahydrophthalic70.9
anhydride
Polymer II from Example 19.64
A
Bisphenol A 19.51
1-Methylimidazole 0.5
Fracture toughness GIs 765
(Double torsion) [J/m2]
Impact toughness (ISO) 35.7
[kJ/m2]
Flexural strength (ISO) 120
[N/mm2]
Extreme fibre extension 6.7
(ISO) [%]
-22-
Examples 8-11: Methyltetrahydrophthalic anhydride and 3,6,9-
trioxaundecanedioic acid
are added to 110 parts by weight of epoxy resin/graft polymer suspension from
Example H
at 60°C and mixed.
The amounts used and the results of the toughness test are shown in Table 8.
Table 8
Parts
by weight
~
Example g 9 10 11
Epoxy resin/graft polymer 110* 110* 110* 110*
suspension
Methyltetrahydrophthalic 62.0 66.5 71.0 71.0
anhydrided
3,6,9-Trioxaundecanedioic 18.1 15.1 12.1 12.1
acid
1-Methylimidazole 0.5 0.5 0.5 0.5
Quartz powder VV12 - - - 290.4
Fracture toughness GIs 2222 1684 1375 700
(Double torsion) [J/m2]
Impact toughness 69.7 62.7 59.0 12.2
(ISO) [kJ/m2]
Flexural strength 124 125 124 122
(ISO) [N/mm2]
Extreme fibre extension 11.0 10.2 10.9 1.9
(ISO) [%]
* 10 parts by weight of toughener to 100 parts by weight of epoxy resin
-23-
Example 12: A mixture of 85 parts by weight of methylhexahydrophthalic
anhydride,
parts by weight of a dicarboxylic acid prepared by reacting 2 mol of
tetrahydrophthalic
anhydride with 1 mol of neopentyl glycol, and 0.2 part by weight of 1-
methylimidazole is
homogenised at 60°C and 100 parts by weight of epoxy resin based on
bisphenol A having
an epoxy content of 5.25-5.40 eq/kg are added at the same temperature. 10
parts by weight
of the toughener Paraloid~ EXL 2600 (Rohm & Haas, USA, particle size: 0.1-0.3
p,m)
and 300 parts by weight of quartz powder W 12 are added in portions to the
mixture while
stirnng vigorously. After addition has been completed, the temperature is
raised to 80°C in
the course of 10 min and the reaction mixture is evacuated to approximately 40-
50 mbar
for 10 min.
The mixture is then cast to produce test pieces. The curing is carried out for
2 h at 100°C
and then for 16 h at 140°C.
The test results are shown in Table 9.
Table 9
Example
12
Glass transition temp. Tg 146
(DSC) [C]
Tensile strength (ISO) [N/mm2]46
Fracture toughness (Double 610
torsion) [J/m2]
Impact toughness (ISO) [kJ/m2]10.7
Flexural strength (ISO) 116
[N/mm2]
Elongation at fracture (ISO)2.06
[%]
