Amine hardener for epoxy resins
View Patent ↗Compounds of formula Ia or Ib wherein A is an (n+1)-valent aliphatic, cycloaliphatic, araliphatic or aromatic radical and n is an integer from 0 to 5, E is an (m+1)-valent aliphatic, cycloaliphatic, araliphatic or aromatic radical and m is an integer from 0 to 3, X is —O—, —C(═O)O or —CHR 4 —, with R 4 and R 3 together forming an ethylene group, R 1 and R 2 are, each independently of the other, hydrogen or methyl, R 3 is hydrogen, or R 3 and R 4 together form an ethylene group, and R 5 is a monovalent aliphatic, cycloaliphatic, araliphatic or aromatic radical, are highly reactive curing agents for epoxy resins and yield cured products having improved resistance to chemicals.
1. A composition comprising:
(A) an epoxy resin and
(B) a compound of formula Ia or Ib
wherein A is an (n +1)-valent aliphatic, cycloaliphatic, araliphatic or aromatic radical and n is an integer from 0 to 5,
E is an (m +1)-valent aliphatic, cycloaliphatic, araliphatic or aromatic radical and m is an integer from 0 to 3,
X in formula Ia is —O—, C(═O)O, or when R 3 is not hydrogen, —CHR 4 — with R 4 and R 3 together forms an ethylene group,
X in formula Ib is —O—, C(═O)O,
R 1 and R 2 are, each independently of the other, hydrogen or methyl,
R 3 is hydrogen, or in formula Ia, R 3 and R 4 together form an ethylene group,
and R 5 is a monovalent aliphatic, cycloaliphatic, araliphatic or aromatic radical.
2. The composition according to claim 1 further comprising
(C) a polyamine.
3. The composition according to claim 1 comprising component B in such amounts that the sum of the amine and mercaptan equivalents is from 0.5 to 2.0 equivalents, based on one epoxy equivalent.
4. A cross-linked product obtained by curing a composition according to claim 1 .
5. The composition according to claim 1 , wherein in the compound of formula Ia, X is —O— and A is a bivalent radical of a bisphenol or of a cycloaliphatic diol, a radical of a phenol novolak or cresol novolak, a bi- to tetra-valent radical of an isocyanate/polyol adduct or a tri- to hexa-valent radical of a tri- to hexa-functional aliphatic polyol.
6. The composition according to claim 1 , wherein in the compound of formula Ia, X is —O— and A is a bivalent radical of formula
a radical of a phenol novolak or cresol novolak, a trivalent radical of formula
or a tetravalent radical of formula
7. The composition according to claim 1 , wherein R 5 is C 1 –C 20 alkyl, C 5 –C 12 - cycloalkyl, C 6 –C 10 aryl or C 7 –C 12 aralkyl, each of which is unsubstituted or substituted by one or more amino groups, hydroxyl groups, C 1 –C 8 alkoxy groups or halogen atoms.
8. The composition according to claim 1 , wherein R 5 is C 2 –C 10 alkyl C 2 –C 10 aminoalkyl, phenyl, benzyl, cyclohexyl or a radical of formula H 2 N—Z—CH 2 —NH—, wherein Z is a bivalent cycloaliphatic, araliphatic or aromatic radical of formula —(CH 2 CH 2 NH) k —CH 2 —, wherein k is 2 or 3.
9. The composition according to claim 1 , wherein R 5 is n-butyl, n-octyl, cyclohexyl, benzyl, 2-aminoethyl, 4-(aminomethyl)pentyl, 5-amino-2-methylpentyl, 3 -dimethylaminopropyl, 3-methylaminopropyl, 4-aminocyclohexyl or a radical of formula
10. The composition according to claim 1 , wherein X is O— and R 1 and R 3 are hydrogen.
11. The composition according to claim 2 , wherein the polyamine is a cycloaliphatic or aliphatic amine.
12. The composition according to claim 11 , wherein the polyamine has the formula R 5 —NH—R 2 or E—(NHR 2 ) m+1 , wherein R 5, R 2, E and m are defined as in claim 1 .
13. The composition according to claim 3 comprising component B in such amounts that the sum of amine and mercaptan equivalents is from 0.8 to 1.5 equivalents, based on one epoxy equivalent.
14. The composition according to claim 13 comprising component B in such amounts that the sum of amine and mercaptan equivalents is from 0.9 to 1.2 equivalents, based on one epoxy equivalent.
15. The composition according to claim 1 , wherein X is —O— or —C(═O)O.