NOVEL COMPOSITIONS FOR PRODUCING CAST POLYAMIDES

1 . A composition comprising

a) solidified lactam melts having 0.1-5% by weight of at least one polymeric carbodiimide, preferably of at least one polymeric aromatic carbodiimide, and/or of at least one uretdione, and

b) solidified lactam melts having 0.2-5% by weight of catalyst selected from the group of: lactam magnesium halide, alkali metal aluminodilactamate, alkali metal and/or alkaline earth metal lactamate,

and/or

c) solidified lactam melts having 0.2-5% by weight of catalyst selected from the group of: lactam magnesium halide, alkali metal aluminodilactamate, alkali metal and/or alkaline earth metal lactamate, and 0.1-5% by weight of at least one polymeric carbodiimide, preferably of at least one polymeric aromatic carbodiimide, and/or of at least one uretdione,

optionally in combination with further solidified lactam melt b).

2 . The composition as claimed in claim 1 , characterized in that compounds of the formula (1)

are used for the lactam melt, where R is an alkylene group having 3 to 13 carbon atoms.

3 . The composition as claimed in claim 1 or 2 , characterized in that the uretdione is prepared proceeding from monomeric compounds which follow, selected from the group of isophorone diisocyanate, cyclohexyl 1,4-diisocyanate, 1,1-methylenebis(4-isocyanatocyclohexane), 1,2-bis(4-isocyanatononyl)-3-heptyl-4-pentylcyclohexane and hexamethylene 1,6-diisocyanate.

4 . The composition as claimed in one or more of claims 1 to 3 , characterized in that the uretdione comprises compounds which are obtained proceeding from an aromatic isocyanate selected from the group consisting of 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, naphthylene 1,5-diisocyanate, methylenediphenyl 4,4′-diisocyanate, 1,3-bis(3-isocyanato-4-methylphenyl)-2,4-dioxodiazetidine, N,N′-bis(4-methyl-3-isocyanatophenyl)urea and tetramethylxylylene diisocyanate.

5 . The composition as claimed in one or more of claims 1 to 4 , characterized in that the polymeric carbodiimide is at least one compound of the formula (II)

R 1 —(—N═C═N—R 2 —) m —R 3   (II),

in which

m is an integer from 2 to 500,

R 1 ═R 2 —NCO, R 2 —NHCONHR 4 , R 2 —NHCONR 4 R 5 or R 2 —NHCOOR 6 ,

R 2 ═C 1 -C 18 -alkylene, C 5 -C 18 -cycloalkylene, arylene and/or C 7 -C 18 -aralkylene, preferably arylene and/or C 7 -C 18 -aralkylene

and

R 3 ═—NCO, —NHCONHR 4 , —NHCONR 4 R 5 or —NHCOOR 6 ,

where R 4 and R 5 in R 1 are the same or different and are each independently a C 1 -C 6 -alkyl, C 6 -C 10 -cycloalkyl or C 7 -C 18 -aralkyl radical and R 6 has one of the definitions of R 1 or is a polyester or polyamide radical or —(CH 2 ) h —O—[(CH 2 ) k —O] g R 4 ,R 4 ,

where 1=1-3, k=1-3, g=0-12 and

R 4 ═H or C 1 -C 4 -alkyl.

6 . The composition as claimed in one or more of claims 1 to 5 , characterized in that the solidified lactam melts having 0.1-5% by weight of at least one polymeric carbodiimide, preferably of at least one polymeric aromatic carbodiimide, and/or of at least one uretdione and/or having 0.2-5% by weight of catalyst selected from the group of: lactam magnesium halide, alkali metal aluminodilactamate, alkali metal and/or alkaline earth metal lactamate, based on the lactam melt, comprise powder, pellets, granules and/or flakes.

7 . A solidified lactam melt having 0.2-5% by weight of catalyst selected from the group of: lactam magnesium halide, alkali metal aluminodilactamate, alkali metal and/or alkaline earth metal lactamate, and 0.1-5% by weight of carbodiimide and/or uretdione, obtainable by mixing

a. at least one melt of caprolactam and 0.1-5% by weight of at least one polymeric carbodiimide, preferably of at least one polymeric aromatic carbodiimide, and/or of at least one uretdione, and

b. at least one melt of caprolactam and 0.2-5% by weight of at least one catalyst selected from the group of: lactam magnesium halide, alkali metal aluminodilactamate, alkali metal and/or alkaline earth metal lactamate,

at temperatures of 70-120° C. over a period of 1-60 seconds, and subsequent finishing with cooling.

8 . A process for producing cast polyamides by polymerizing one or more of the constituents from one or more of claims 1 to 4 in the casting mold at temperatures of 100 to 160° C.

9 . A cast polyamide obtainable by polymerizing a composition as claimed in one or more of claims 1 to 6 .

10 . The use of one or more constituents of the composition as claimed in one or more of claims 1 to 4 for production of cast polyamides.