Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-06-15
2002-10-15
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C525S453000, C525S484000, C525S523000, C528S149000
Reexamination Certificate
active
06465601
ABSTRACT:
The present invention relates to compounds that are active as accelerators for curable epoxy and polyurethane systems. The invention relates especially to new compounds that are obtained as reaction products of Mannich bases described hereinbelow with selected amines by means of transamination and that can be used as accelerators in curable epoxy and polyurethane systems.
Numerous curable epoxy systems are known. For certain applications, however, those systems have the disadvantage that they cure too slowly at comparatively low temperatures, that is to say at 5° C. or lower. When the atmospheric humidity is, at the same time, relatively high, this results, for example, in coatings or films of inadequate quality being obtained, for example with respect to flexibility, odour, gloss or tackiness. It has now been found that the new compounds according to the invention described hereinbelow are excellently suitable for use as accelerators in curable epoxy and polyurethane systems, the curing rate of the mentioned systems at low temperatures down to −5° C. being increased to such an extent that the described disadvantageous influence of high atmospheric humidity is substantially or completely overcome. The compounds according to the invention also have the advantage that they are of low molecular weight and comparatively low viscosity. They are therefore readily miscible with the compounds of the curable systems and positively influence the properties of the cured systems. The accelerators according to the invention are, moreover, chemically bonded in the cured systems, which means that the compounds according to the invention can be used in significantly higher concentrations. That is of fundamental importance at low temperatures (<5° C.) and currently cannot be achieved with known accelerators, which are not incorporated in the crosslinked network and render the network unusable at relatively high concentrations.
The present invention is defined in the patent claims. The present invention relates especially to compounds that are active as accelerators for curable epoxy and polyurethane systems, characterised in that the compounds are prepared by means of a transamination reaction by reacting
(a) a substituted phenolic compound (Mannich base) having at least one substituent of formula
R
1
(R
2
)N—CH(R
3
)— (A),
wherein R
1
and R
2
are each independently of the other linear or branched C
1
-C
4
alkyl and R
3
is hydrogen, methyl, ethyl or phenyl, with
(b) a compound of formula
R
4
(R
5
)N—C
n
H
2n
—(NH—C
n
H
2n
)
q
—NH
2
(B),
wherein R
4
and R
5
are each independently of the other C
1-6
alkyl or together form a radical of formula —(CH
2
)
5
— or —(CH
2
)
2
—O—(CH
2
)
2
—, n is an integer from 2 to 5 and q is zero, 1, 2 or 3, and the compound obtained or the compounds present in the mixture obtained has/have on average, per molecule, at least one substituent of formula
(R
4
)(R
5
)N—C
n
H
2n
—(NH—C
n
H
2n
)
q
—NH—CH(R
3
)—,
wherein the substituents R
3
, R
4
, R
5
, n and q have the meanings given above.
The present invention relates also to a process for the preparation of the compounds of the invention, which are active as accelerators, which process is characterised in that, by means of a transamination reaction, (a) a substituted phenolic compound (Mannich base) having at least one substituent of formula
R
1
(R
2
)N—CH(R
3
)— (A)
is so reacted with (b) a compound of formula
R
4
(R
5
)N—C
n
H
2n
—(NH—C
n
H
2n
)
q
—NH
2
(B),
wherein R
1
, R
2
, R
3
, R
4
, R
5
, n and q have the meanings given above, that the compound obtained or the compounds present in the mixture obtained has/have on average, per molecule, at least one substituent of formula
(R
4
)(R
5
)N—C
n
H
2n
—(NH—C
n
H
2n
)
q
—NH—CH(R
3
)—,
wherein the substituents R
3
, R
4
, R
5
, n and q have the meanings given above.
The present invention relates also to the use of the compounds according to the invention as accelerators in curable systems, especially in curable epoxy and polyurethane systems.
The present invention relates also to curable systems, especially curable epoxy and polyurethane systems, comprising a compound according to the invention or a mixture of such compounds, and also to the cured products produced therefrom.
The substituted phenolic compounds (Mannich bases) are preferably low-molecular-weight-di-alkylaminomethyl-substituted phenols, ortho-, meta- and para-cresols, the isomeric xylenols, para-tert-butylphenol, para-nonylphenol, &agr;-naphthol, &bgr;-naphthol, diphenols or polyphenols, preferably resorcinol, hydroquinone, 4,4′-dihydroxydiphenyl, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenylmethane, bisphenol A, and the condensation products of phenol and formaldehyde termed novolaks. Preference is given to di-C
1
-C
4
alkylaminomethyl-substituted phenols and cresols, especially substituted phenol.
Preferably, R
1
and R
2
are each independently of the other methyl or ethyl; R
1
and R
2
are preferably methyl. R
3
is preferably hydrogen, methyl or ethyl, preferably hydrogen.
The substituent (A) is preferably di-C
1
-C
4
alkylaminomethyl, especially dimethylaminomethyl, ethylmethylaminomethyl and diethylaminomethyl, especially dimethylaminomethyl. The decisive criterion is that it should be possible for the low-molecular-weight dialkylamine liberated in the transamination reaction to be readily removed, by virtue of its low boiling point, from the reaction mixture.
The substituted phenolic compounds are so-called Mannich bases. They are obtained in a manner known per se by reacting the phenolic compound with formaldehyde, acetaldehyde, propionaldehyde or benzaldehyde and the appropriate amine.
Mannich bases preferably used are substituted phenols of formulae (I), (IIa), (IIb) and (III), with preference being given to compounds of formulae (IIa) and (III). In practice, a mixture of those compounds may also be used. The radicals R
1
and R
2
are as defined for formula (A).
The substituted phenolic compounds mentioned hereinabove are derived in analogous manner to the phenols of formulae (I), (IIa), (IIb) and (III) mentioned by way of example.
In accordance with the invention, the Mannich bases described above are reacted, by means of a transamination reaction, with compounds of formula (B)
R
4
(R
5
)N—C
n
H
2n
—(NH—C
n
H
2n
)
q
—NH
2
(B).
Preferably, R
4
and R
5
therein are each independently of the other C
1-4
alkyl, preferably methyl or ethyl. R
4
and R
5
are preferably methyl. n is preferably 2, 3 or 4, preferably 3. q is preferably zero or 1, preferably zero.
In accordance with the preferred meanings, the corresponding reaction products are also obtained in the transamination reaction.
For example, reaction of the compound of formula (III) with dimethylaminopropylamine results in the following Reaction Scheme 1, wherein H
2
NR is dimethylaminopropylamine and DMA is the leaving group dimethylamine.
Scheme 1
By means of transamination, only one dimethylaminomethyl substituent or only two of the substituents, of which there are at most three, may, as desired, be brought to reaction, the unreacted dimethylaminomethyl substituent(s) remaining unchanged on the phenolic nucleus. The above Scheme 1 also shows (bottom row) that, on continuation of the reaction, dimerisation and further reaction to linear and branched oligomeric forms occur. Scheme 2 shows the general structure of the oligomeric forms that are then formed.
Scheme 2
In the above compound of formula (IV), —(CH
2
)
s
— corresponds to the radical —C
n
H
2n
— as defined for the compound of formula B.
As will be seen from Scheme 1 and Scheme 2, R
6
may be hydrogen, a radical —(CH
2
)
S
—N(R
4
)R
5
or an oligomeric radical.
Reaction of the Mannich bases of formulae (I), (IIa) and (III) with dimethylaminopropylamine, results, for example, in the following monomeric compounds of formulae (V), (VI), (VII), (VIII), (IX) and (X), amongst others, depending on the starting material:
The compounds
Dobinson Bryan
Fischer Walter
Wiesendanger Rolf
Neuman Kristin H.
Proskauer Rose LLP
Sellers Robert E. L.
Vantico Inc.
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