Molding polyamides, methods for the production thereof, and use thereof

1. A cast polyamide comprising a reaction product of:

a) a catalyst for the anionic polymerization of lactams;

b) an activator for the anionic polymerization of lactams, wherein the activator is at least one compound selected from the group consisting of biurets, and uretdiones;

c) at least one coactivator selected from the group consisting of tert-amines; and

d) a lactam,

wherein the components a), b), c) and d) are combined and cast at a temperature of 80° C. to 130° C.

2. The cast polyamide as claimed in claim 1 , wherein the catalyst is at least one compound selected from a group consisting of lactam magnesium halides, alkali metal aluminodilactamates, alkali metal and/or alkaline earth metal lactamates, potassium lactamates, and magnesium lactamates.

3. The cast polyamide as claimed in claim 1 , wherein the activator is at least one biuret.

4. The cast polyamide as claimed in claim 1 , wherein the activator is at least one uretdione.

5. The cast polyamide as claimed in claim 1 , wherein:

the coactivator is triethylenediamine;

the lactam corresponds to lactams of the general formula

 where R is an alkylene group having 3 to 13 carbon atoms; and

the combined components are cast in an injection casting, stationary casting, or rotary casting process.

6. The cast polyamide as claimed in claim 1 , wherein the components a), b) and c) are present in the following proportions based on the lactam:

a) 0.1 to 3% by weight,

b) 0.1 to 2% by weight, and

c) 0.0005 to 02% by weight.

7. A process for producing the cast polyamide as claimed in claim 1 , the process comprising:

mixing at least one lactam melt with the catalyst a) to produce a first mixture,

mixing at least one lactam melt with the activator b) to produce a second mixture,

at least one of:

mixing a lactam melt with the coactivator c) to produce a third mixture, and

mixing the coactivator c) with at least one of:

the first mixture of lactam melt and catalyst a), and

the second mixture of lactam melt and activator b), and

combining the first mixture, the second mixture, and if the first and/or second mixture does not contain the coactivator c), also the third mixture at a temperature of 80° C. to 130° C. to produce a reaction mixture for polymerizing the lactam melts, and casting the reaction mixture at the temperature of 80° C. to 130° C.

8. A roller, a semifinished product or a sheet for mechanical engineering prepared with a polyamide according to claim 1 .

9. The cast polyamide as claimed in claim 1 , wherein:

the catalyst is at least one compound selected from a group consisting of lactam magnesium halides, alkali metal aluminodilactamates, alkali metal and/or alkaline earth metal lactamates, potassium lactamates and magnesium lactamates;

the activator is at least one compound selected from the group consisting of biurets, and uretdiones;

the lactam corresponds to compounds of general formula

 where R is an alkylene group having 3 to 13 carbon atoms; and

the temperature is 80° C. to <130° C.

10. The cast polyamide as claimed in claim 9 , wherein components a), b) and c) are present in the following amounts based on the lactam:

a) 0.1 to 3% by weight,

b) 001 to 2% by weight, and

c) 0.0005 to 02% by weight.

11. The cast polyamide as claimed in claim 10 , wherein the temperature is 110° C. to 130° C.

12. The cast polyamide as claimed in claim 11 , wherein;

the coactivator is triethylenediamine;

the activator is at least one biuret; and

the lactam is at least one of caprolactam and laurolactam.

13. The cast polyamide as claimed in claim 11 , wherein:

the coactivator is triethylenediamine;

the activator is at least one uretdione; and

the lactam is at least one of caprolactam and laurolactam.

14. The cast polyamide as claimed in claim 9 , wherein:

components a), b) and c) are present in the following amounts based on the lactam:

a) 0.2 to 1.5% by weight,

b) 0.5 to 1% by weight, and

c) 0.005 to 0.1% by weight; and

the activator is at least one of: hexamethylene diisocyanate biuret and toluene diisocyanate uretdione;

the catalyst is sodium caprolactamate; and

the temperature is 110° C. to 130° C.

15. The cast polyamide as claimed in claim 1 , wherein the cast polyamide is produced by reaction of at least:

a) sodium lactamate as an 18-20% by weight caprolactam solution,

b) at least one activator selected from the group consisting of a uretdione based on 2,4-diisocyanatotoluene, and a biuret of the formula (IV)

 with p=6,

c) triethylenediamine, and

d) caprolactam.

16. The cast polyamide as claimed in claim 15 , wherein:

the cast polyamide is produced by reaction of components a), b), c) and d);

components a), b) and c) are present in the following amounts based on the lactam:

a) 1 to 2% by weight,

b) 0.5 to 1% by weight, and

c) 0.005 to 0.1% by weight; and

the temperature is 110° C. to 130° C.