CURABLE CYANATE COMPOSITIONS

COMPOSITIONS DE CYANATE DURCISSABLES

English Abstract

Disclosed are hardenable compositions based on bifunctional or polyfunctional
aromatic
cyanates. Said compositions comprise: a) 10 - 100 wt. %, in relation to the
sum of components
(a) and (b), of a bi- or polyfunctional aromatic cyanate or prepolymer
consisting of at least one
bifunctional or polyfunctional aromatic cyanate or a mixture of the
abovementioned cyanates
and/or prepolymers; b) b) 0 - 90 wt %, in relation to the sum of components
(a) and (b), of
monofunctional, bifunctional or polyfunctional epoxy resin; c) 0.5 - 30 wt. %,
in relation to the
sum of components (a) and (b), of monofunctional or polyfunctional aromatic
amine and d)
0 - 5 wt. %, in relation to the sum of components (a) and (b), of a catalyst
from the group consisting
of transitional metal compounds and bortirhalogenides. After hardening, the
inventive
compositions provide duroplastics which have a high glass transition
temperature and which are
especially suitable for use in the production of high-temperature-resistant
molded items for
electrical appliances or the automobile and aviation construction industry.

French Abstract

La présente invention concerne des compositions durcissables à base de cyanates aromatiques bifonctionnels ou polyfonctionnels. Ces compositions comprennent au moins (a) de 10 à 100 % en poids, par rapport à la somme des composants (a) et (b), d'un cyanate aromatique bifonctionnel ou polyfonctionnel ou d'un prépolymère constitué d'au moins un cyanate aromatique bifonctionnel ou polyfonctionnel ou d'un mélange des cyanates et/ou des prépolymères susmentionnés, (b) de 0 à 90 % en poids, par rapport à la somme des composants (a) et (b), d'une résine époxy monofonctionnelle, bifonctionnelle ou polyfonctionnelle, (c) de 0,5 à 30 % en poids, par rapport à la somme des composants (a) et (b), d'une amine aromatique monofonctionnelle ou polyfonctionnelle et (d) de 0 à 5 % en poids, par rapport à la somme des composants (a) et (b), d'un catalyseur choisi dans le groupe formé par des composés à base de métal de transition et des trihalogénures de bore. Les compositions selon cette invention donnent, après durcissement, des plastiques thermodurcissables qui présentent une température de transition vitreuse élevée et qui conviennent notamment à la production de pièces moulées résistantes aux températures élevées, utilisées dans des appareils électroniques ou dans le domaine de la construction automobile et aéronautique.

Claims

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THE EMBODIMENTS OF THE PRESENT INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A curable mixture, at least comprising
(a) 10 to 100% by weight, in relation to the sum of the components (a) and
(b), of at least
one bi- or polyfunctional aromatic cyanate or a prepolymer formed from at
least one bi-
or polyfunctional aromatic cyanate or a mixture formed from the abovementioned
cyanates and/or prepolymers,
(b) 0 to 90% by weight, in relation to the sum of the components (a) and (b),
of at least one
mono-, bi- or polyfunctional epoxy resin,
(c) 0.5 to 30% by weight, in relation to the sum of the components (a) and (b)
of at least one
mono-, bi- or polyfunctional aromatic amine, and
(d) 0 to 5% by weight, in relation to the sum of the components (a) and (b),
of at least one
catalyst selected from the group consisting of transition metal compounds and
boron
trihalides.
2 The curable mixture according to claim 1, wherein the bi- or polyfunctional
aromatic
cyanate is selected from the group consisting of the compounds of the general
formulae
<IMG>
in which R1 is hydrogen, methyl or bromine and X is selected from the group
consisting of -CH2-,
-CH(CH3)-, -C(CH3)2-,-C(CF3)2-, -O-, -S-,
-SO2-, -C(=O)-, -OC(=O)-, -OC(=O)O- and

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<IMG>
in which n is a number from 0 to 10 and R 2 is hydrogen or methyl;
and
<IMG>
and which n has the abovementioned meaning,
and prepolymers formed from one or more of these compounds.
3. The curable mixture according to claim 1 or 2, wherein the epoxy resin is
selected from
the group consisting of the compounds of the general formulae
<IMG>
in which R1 and X have the meanings mentioned in claim 2, and the
corresponding oligomers,

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<IMG>
in which n and R2 have the meanings mentioned in claim 2,
and
<IMG>
in which n has the abovementioned meaning.
4. The curable mixture according to any one of claims 1 to 3, wherein the
aromatic amine
is selected from the group consisting of the compounds of the general formulae
<IMG>
in which R3, R4 and R5 are, independently of one another, hydrogen, C1-4 alkyl
or halogen, and

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<IMG>
in which R6, R7 and R8 are, independently of one another, hydrogen or C1-4-
alkyl.
5. A polytriazine-based thermosetting substance, obtained by thermal curing of
the mixture
according to any one of claims 1 to 4.
6. A polytriazine-based thermosetting substance, obtained by thermal curing of
the mixture
according to any one of claims 1 to 4 with addition of fillers and/or
auxiliaries.
7. The use of the thermosetting substance according to claim 5 or 6 in the
preparation of
molded items for electronic equipment, aircraft, spacecraft, road vehicles,
rail vehicles,
watercraft and industrial purposes.

Description

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Curable cyanate compositions
Field of the Invention
The invention relates to curable mixtures formed from aromatic cyanates or
cyanate/epoxide
mixtures, aromatic amines and optionally catalysts for the preparation of
polytriazine-based
thermosetting materials. It additionally relates to the thermosetting
substances obtainable by
curing these mixtures and to their use in the preparation of molded items.
Background of the Invention
It is true that it is also possible to cure the abovementioned starting
materials by a purely
thermal route but the curing is usually carried out by addition of
catalytically effective transition
metal compounds, such as, for example, cobalt or copper acetylacetonate or
zinc octanoate
("zinc octoate"). However, because of their toxicity and/or danger to the
environment (in
particular in the disposal of materials prepared with them), and the possible
influencing of the
electrical and magnetic properties, these are per se undesirable.
Summary of the Invention
The polytriazines obtainable from bi- or polyfunctional aromatic cyanates and
the thermosetting
materials obtainable from the abovementioned cyanates and epoxy resins are
valuable
materials because of their outstanding heat-resistance and good dielectric
properties. In each
case, the term polyfunctional cyanates, polyfunctional epoxides or
polyfunctional amines are
understood to mean, here and subsequently, compounds comprising three or more
cyanate,
epoxy or amino groups in a molecule.
Accordingly an aspect of the present invention is to make available
alternative additives for the
curing of aromatic cyanates and cyanate/epoxide mixtures which do not exhibit
the
abovementioned disadvantages.
This aspect is achieved according to the present invention by a curable
mixture, at least
comprising (a)10 to 100% by weight, in relation to the sum of the components
(a) and (b), of at
least one bi- or polyfunctional aromatic cyanate or a prepolymer formed from
at least one bi- or
polyfunctional aromatic cyanate or a mixture formed from the abovementioned
cyanates and/or
prepolymers, (b) 0 to 90% by weight, in relation to the sum of the components
(a) and (b), of at
least one mono-, bi- or polyfunctional epoxy resin, (c) 0.5 to 30% by weight,
in relation to the
sum of the components (a) and (b) of at least one mono-, bi- or polyfunctional
aromatic amine,
and (d) 0 to 5% by weight, in relation to the sum of the components (a) and
(b), of at least one

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catalyst selected from the group consisting of transition metal compounds and
boron trihalides.
It has been found, surprisingly, that, by the use of aromatic amines as curing
agent of bi- or
polyfunctional cyanates ortheir mixtures with epoxides, not only can catalysts
comprising heavy
metals be dispensed with but also products with outstanding properties are
obtained after
curing. Thus, the glass transition temperature (Tg) in particular is markedly
increased and the
cured products exhibit an improved impact strength. In addition, the through-
curing is improved
and the curing pattern, in particular the latency in the curing, is improved.
The curable mixtures according to an aspect of the present invention comprise
at least the
following constituents:
(a) 10 to 100% by weight, in relation to the sum of the components (a) and
(b), of at least
one bi- or polyfunctional aromatic cyanate or a prepolymer formed from at
least one bi-
or polyfunctional aromatic cyanate or a mixture formed from the abovementioned
cyanates and/or prepolymers,
(b) 0 to 90% by weight, in relation to the sum of the components (a) and (b),
of at least one
mono-, bi- or polyfunctional epoxy resin,
(c) 0.5 to 30% by weight, in relation to the sum of the components (a) and (b)
of at least one
mono-, bi- or polyfunctional aromatic amine, and
(d) 0 to 5% by weight, in relation to the sum of the components (a) and (b),
of at least one
catalyst selected from the group consisting of transition metal compounds and
boron
trihalides.
Transition metal compounds are to be understood as meaning both salts and
coordination
compounds, the transition metals in particular being able to be first-row and
second-row
transition metals. This includes, for example, coordination compounds, such as
cobalt or copper
acetylacetonate, or salts, such as zinc octanoate or zinc stearate.
Boron trihalides that are particularly useful for boron trifluoride and boron
thrichloride.
Preferably the bi- or polyfunctional aromatic cyanates used are those selected
from the group
consisting of compounds of the general formulae
R
NCO OCN
R RI

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in which R' is hydrogen, methyl or bromine and X is a divalent organic radical
chosen from the
group consisting of -CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, -0-, -S-, -SO2-, -
C(=O)-, -OC(=O)-,
-OC(=O)O- and
CH3
CH3
H
3
H3
OCN OCN
OCN
R2
\ \ \ RZ
n
in which n is a number from 0 to 10 and R2 is hydrogen or methyl;
and
OCN
OCN
in which n has the abovementioned meaning. Mixtures of these compounds,
prepolymers of
these compounds, prepolymers formed from mixtures of these compounds and
mixtures formed
from prepolymers of these compounds can likewise also be used. Prepolymers are
to be
understood as the oligomers obtainable by partial trimerization. These
comprise both triazine
groups produced by trimerization and unreacted cyanate groups. The cyanates
are known
compounds and are in many cases available commercially; likewise, the
prepolymers are known
and are in some cases available commercially or can be readily prepared from
the cyanates.
Preferably the epoxy resins used are those selected from the group consisting
of the
compounds of the general formulae
R R
O \ x
R

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in which R' and X have the abovementioned meanings, and the corresponding
oligomers;
O O O
O Y
Rz
C RZ (V),
R/
n
in which n and R2 have the abovementioned meanings:
and
0 0
0
n
in which n has the abovementioned meaning. These compounds are also known and
are
available commercially from various manufacturers.
Preferably the aromatic amines used are those selected from the group
consisting of the
compounds of the general formulae
R3
R5 Ra
N C (),
R4 R5 R3

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in which R3, R4 and R5 are, independently of one another, hydrogen, C1.4-alkyl
or halogen, and
R6 NH2 (VIII),
R 8
in which R6, R' and R8 are, independently of one another, hydrogen or C1.4-
alkyl. These
compounds are also known and are in many cases available commercially.
Compounds of the
formula VII are, for example, used as chain extenders in polyurethanes and
those of the formula
VIII as amine component in polyureas or as starting materials for the
preparation of isocyanates.
The polytriazine-based thermosetting substances obtainable by thermal curing
of the mixtures
described above, optionally with addition of fillers and/or auxiliaries, are
likewise subject matter
of the invention. Fillers and auxiliaries are to be understood as in
particular reinforcing materials
in the form of fabrics, fibers or particles, colorants or other additives for
obtaining particular
mechanical, optical, electrical or magnetic properties or for improving the
processing
characteristics. These fillers and auxiliaries are known to a person skilled
in the art.
The use of the thermosetting substances thus obtainable in the preparation of
molded items for
electronic equipment, aircraft, spacecraft, road vehicles, rail vehicles,
watercraft and industrial
purposes is an additional subject matter of the invention.
The following exemplary embodiments clarify the invention without a limitation
to be seen
therein.
Examples 1-8
Mixtures of cyanates (Primaset PT 15 from Lonza AG; formula II, R2 = H,
viscosity 20-30 Pas
at 80 C), optionally epoxide (Dow DER 330; formula IV, R1=H, X = -C(CH3)2-),
and amine
(Lonzacure DETDA from Lonza AG, formula VIII, R' = R' = Et, R8 = Me, mixture
of isomers)
were prepared and thermally cured. The glass transition temperature (T9) was
determined from
the cured test specimens by thermomechanical analysis. The mixing proportions,
curing
conditions and glass transition temperatures are summarized in the following
table 1.

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Table I
Example Epoxide Cyante Amine Tg Cure Cure time
No. [g] [g] [g] [ C] temperature [min]
IOC]
1 - 100 1.0 361 150 60
2 - 100 2.5 3611) 150 60
3 - 100 5.0 368 150 60
4 - 100 10.0 377 150 60
5 75 25 2.5 375 150 60
6 75 25 5.0 367 150 60
7 75 25 10.0 351 150 60
8 75 25 10.0 378 150/200/250 180/180/180
1) after complete curing (2nd measuring cycle)
Examples 9-12
Processing was carried out as described in the above examples but using
Lonzacure M-CDEA
(formula VII, R3 = R4 = Et, R5 = Cl) as the amine. The results are summarized
in the following
table 2.
Table 2
Example Epoxide Cyante Amine T9 Cure Cure time
No. [g] 191 [g] IOC] temperature [min]
[ C]
9 - 100 5.0 384') 150 60
10 75 25 2.5 366 150/200/250 180/180/180
11 75 25 5.0 362 150 60
12 75 25 10.0 -r370T 150 60
'~ after complete curing (2nd measuring cycle)

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Examples 13-16
Processing was carried out as described in examples 9-12 but using the cyanate
Primaset CT
90 (formula II, R2 = Me, softening point ) 60 C) instead of the cyanate
Primaset PT 15. The
results are summarized in the following table 3.
Table 3
Example Epoxide Cyante Amine Tg Cure Cure time
No. [g] [g] [g] [ C] temperature [min]
[ C]
13 75 25 5.0 3691) 150 60
14 75 25 5.0 376 150/200/250 180/180/180
15 75 25 10.0 372 150 60
16 75 25 10.0 373 150/200/250 180/180/180
'~ after complete curing (2nd measuring cycle)