Preparation of cast polyamides using special activators
The present invention relates to a system comprising a) at least one catalyst for the anionic polymerization of lactams, and b) at least one activator for the anionic polymerization of lactams, wherein the at least one activator is a cyclic isocyanate, at least one allophanate or a mixture thereof.
1. A system, comprising:
a) at least one catalyst capable of anionic polymerization of lactams selected from the group consisting of alkali metals, alkali metal salts of lactams, alkali metal hydrides, alkali metal alcoholates, alkali metal hydroxides and organo-metallic compounds; and
b) at least one activator capable of anionic polymerization of lactams, wherein the at least one activator is a uretdione based on 1,4-cyclohexyl diisocyanate, hexamethylene-1,6-diisocyanate, isophorone diisocyanate, 1,4-cyclohexyl diisocyanate, 1,1-methylene-bis-(4-isocyanatocyclohexane), 1,2-bis-(9-isocyanatononyl) -3-heptyl-4-pentylcyclohexane, tetramethylxylylene diisocyanate, 4,4′-methylene diphenyldiisocyanate, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 1,5-naphthylene diisocyanate,1,3-bis-(3-isocyanato-4-methylphenyl)-2,4-dioxodiazetidine, and/or N,N′-bis-(4-methyl-3-isocyanatophenyl)-urea.
2. The system according to claim 1 , wherein the content of the at least one activator for the anionic polymerization of lactams, relative to the at least one catalyst for the anionic polymerization of lactams, is 5 to 500% by wt.
3. The system according to claim 1 , further comprising at least one lactam.
4. The system according to claim 3 , wherein the lactam comprises at least 4 carbon atoms in the ring.
5. The system according to claim 3 , wherein the lactam is selected from the group consisting of caprolactam, oenathic lactam, caprylic lactam, lauryl lactam, lauric lactam and mixtures thereof.
6. The system according to claim 5 , wherein the lactam is ε-caprolactam.
7. The system according to claim 1 , further comprising at least one hydrophobic silicic acid.
8. The system according to claim 1 , further comprising at least one additive selected from the group consisting of reinforcing fillers, non-reinforcing fillers, flameproofing agents, deforming agents, lubricants, antistatic agents, agents for increasing thermal conductivity, agents for increasing electrical conductivity, colorants, pigments, stabilizers, antihydrolysis agents, antioxidants, softeners, antiblocking agents, thickeners, impact resistance modifiers and auxiliary processing substances.
9. A kit comprising the system according to claim 1 .
10. A process for the preparation of cast polyamides comprising providing the system according to claim 1 to a mould.
11. A process for preparing polyamides by anionic polymerization of lactams comprising providing the system according to claim 1 .
12. A polyamide obtained by the process according to either claim 10 or 11 .