Amine for rapid-curing epoxy resin compositions
An amine of formula (I) which is particularly suitable for use as a curing agent for epoxy resins. The amine of formula (I) is devoid of non-incorporable toxic phenols, and is low-viscosity and pale in color. It allows the production of easily-workable, low-emission or emission-free epoxy resin products which cure rapidly even at relatively low ambient temperatures thus obtaining a high degree of hardness and a nice surface with hardly any yellowing. This is particularly suited to use in floor or top coatings.
1. An amine of the formula (I),
where
m is 0 or 1 or 2,
n is 1 or 2 or 3,
R is a hydrogen radical or alkyl radical having 1 to 8 carbon atoms or phenyl radical, and
X represents identical or different radicals selected from the group consisting of hydroxyl, alkyl, alkenyl and alkoxy, N-pyrrolidinylmethyl, N-piperidinylmethyl, and N-morpholiynlmethyl, wherein each of said alkyl, alkenyl and alkoxy has up to 18 carbon atoms and optionally contains ether oxygen, hydroxyl oxygen or amine nitrogen.
2. The amine as claimed in claim 1 , wherein m is 0 or 1, n is 1, and R is a hydrogen radical or methyl radical.
3. The amine as claimed in claim 1 , wherein (m+n) is 3, R is a hydrogen radical, and X is an N,N-dialkyl radical which optionally contains one or two hydroxyl groups, or is an N-alkyl radical which optionally contains a hydroxyl group or one or two amine nitrogens, or is an N-pyrrolidinylmethyl or N-piperidinylmethyl or N-morpholinylmethyl radical.
4. A process for preparing the amine as claimed in claim 1 , wherein 1,2-propylenediamine is reacted
either, with reductive alkylation, with at least one aldehyde or ketone of the formula (II) and hydrogen
or, with transamination, with a Mannich base of the formula (III)
where
R 1 and R 2 are each identical or different alkyl, cycloalkyl or aralkyl radicals having 1 to 4 carbon atoms and optionally containing ether oxygen or amine nitrogen, or together are an alkylene radical having 4 to 8 carbon atoms and optionally containing ether oxygen or amine nitrogen.
5. The process as claimed in claim 4 , wherein it is carried out with a ratio between the number of 1,2-propylenediamine molecules and the number of aldehyde or keto groups in the aldehyde or ketone of the formula (II) of at least 1.5/1.
6. The process as claimed in claim 4 , wherein it is carried out with salicylaldehyde or 2′-hydroxyacetophenone as aldehyde or ketone of the formula (II).
7. The process as claimed in claim 4 , wherein it is carried out with a ratio between the number of 1,2-propylenediamine molecules and the number of aminoalkyl substituents in the Mannich base of the formula (III) of at least 1/1.
8. The process as claimed in claim 4 , wherein it is carried out with 2,4,6-tris(N,N-dimethylaminomethyl)phenol as Mannich base of the formula (III).
9. A hardener for epoxy resins comprising at least one amine as claimed in claim 1 .
10. A hardener for epoxy resins, comprising at least one amine as claimed in claim 1 and at least one further amine and/or at least one additive.
11. The hardener as claimed in claim 10 , wherein the further amine is selected from the group consisting of 2-butyl-2-ethyl-1,5-pentanediamine, 2,2(4),4-trimethylhexamethylenediamine, 1,12-dodecandiamine, bis(4-aminocyclohexyl)methane, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 2,5(2,6)-bis(aminomethyl)bicyclo[2.2.1]heptane, 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0 2,6 ]decane, 1,4-diamino-2,2,6-trimethylcyclohexane, 1,8-menthanediamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3-bis(aminomethyl)benzene, aliphatic primary di- and triamines containing ether groups, N 1 -benzyl-1,2-propanediamine, N 1 -(4-methoxybenzyl)-1,2-propanediamine, N-benzyl-1,3-bis(aminomethyl)benzene, N,N′-dibenzyl-1,3-bis(aminomethyl)benzene, N-2-ethylhexyl-1,3-bis(aminomethyl)benzene, N,N′-bis(2-ethylhexyl)-1,3-bis(aminomethyl)benzene, partially styrenized 1,3-bis(aminomethyl)benzene, and adducts of (i) at least one polyamine having at least three amine hydrogens that are reactive toward epoxide groups with (ii) at least one epoxide.
12. The hardener as claimed in claim 11 , wherein the further amine is N 1 -benzyl-1,2-propanediamine.
13. An epoxy resin composition comprising
a resin component comprising at least one epoxy resin, and
a hardener component comprising at least one amine as claimed in claim 1 .
14. A coating obtained from an epoxy resin composition as claimed in claim 13 .
15. A method for accelerating the curing of an epoxy resin composition, wherein an amine as claimed in claim 1 is added.