HEAT-AGING RESISTANT POLYAMIDE MOLDING COMPOSITIONS

Abstract

Described herein is a thermoplastic molding composition, including 30 to 99.8 wt % of at least one thermoplastic polyamide as component A; 0.001 to 5 wt % of at least one polyethylenimine homo-or copolymer as component B; 0.1 to 2.0 wt % of at least one condensation product of secondary aryl amines and aliphatic aldehydes, aliphatic ketones, or mixtures thereof, or a combination of at least one secondary aryl amine and the at least one condensation product as component C; 0 to 3 wt % of at least one lubricant as component D; 0 to 50 wt % of at least one fibrous and/or particulate filler as component E; and 0 to 25 wt % of further additives as component F, where a total of wt % of components A to F is 100 wt %, which is free from copper.

Claims

1. A thermoplastic molding composition, comprising a) 30 to 99.8 wt % of at least one thermoplastic polyamide as component A; b) 0.001 to 5 wt % of at least one polyethylenimine homo-or copolymer as component B; c) 0.1 to 2.0 wt % of at least one condensation product of secondary aryl amines and aliphatic aldehydes, aliphatic ketones, or mixtures thereof, or a combination of at least one secondary aryl amine and the at least one condensation product as component C; d) 0 to 3 wt % of at least one lubricant as component D; e) 0 to 50 wt % of at least one fibrous and/or particulate filler as component E; and f) 0 to 25 wt % of further additives as component F, wherein a total of wt % of components A to F is 100 wt %, which is free from copper.

2. The thermoplastic molding composition according to claim 1, wherein component B is selected from the group consisting of homopolymers of ethylenimine, copolymers of ethylenimine and amines having at least two amino groups, crosslinked polyethylenimines, grafted polyethylenimines, amidated polymers obtainable by reaction of polyethylenimines with carboxylic acids or carboxylic esters, carboxylic anhydrides, carboxamides or carbonyl halides, alkoxylated polyethylenimines, hydroxyl-containing polyethylenimines, amphoteric polyethylenimines and lipophilic polyethylenimines.

3. The thermoplastic molding composition according to claim 1, wherein component B has a weight average molecular weight M.sub.w of 100 to 3000000 g/mol.

4. The thermoplastic molding composition according to claim 1, wherein component B is a polyethylenimine homopolymer having a weight average molecular weight M.sub.w of 10000 to 50000 g/mol.

5. The thermoplastic molding composition according to claim 1, wherein component D is selected from the group consisting of aluminum salts, alkali metal salts, alkaline earth metal salts, esters or amides, and fatty acids having from 10 to 44 carbon atoms.

6. The thermoplastic molding composition according to claim 1, which is free from metal halides.

7. The thermoplastic molding composition according to claim 1, wherein component C comprises or is at least one condensation product of diaryl amine with formaldehyde and/or acetone.

8. The thermoplastic molding composition according to claim 7, wherein component C further comprises at least one secondary aryl amine.

9. The thermoplastic molding composition according to claim 1, wherein component D is present in an amount of from 0.05 to 3 wt %.

10. The thermoplastic molding composition according to claim 1, wherein component E comprises glass fibers, and is present in an amount of from 10 to 50 wt %.

11. A process for preparing the thermoplastic molding composition according to claim 1 by mixing the components A to F.

12. A method of using the thermoplastic molding composition according to claim 1, the method comprising using the thermoplastic molding composition for producing fibers, foils or moldings of any type.

13. A fiber, foil or molding, made of the thermoplastic molding composition according to claim 1.

14. (canceled)

15. (canceled)

16. The thermoplastic molding composition according to claim 1, wherein component B has a weight average molecular weight M.sub.w of 500 to 2000000 g/mol.

17. The thermoplastic molding composition according to claim 1, wherein component B has a weight average molecular weight M.sub.w of more than 700 to 1500000 g/mol.

18. The thermoplastic molding composition according to claim 1, wherein component D is present in an amount of from 0.1 to 1.5 wt %.

19. The thermoplastic molding composition according to claim 1, wherein component D is present in an amount of from 0.1 to 1.0 wt %.

20. The thermoplastic molding composition according to claim 1, wherein component E comprises glass fibers, and is present in an amount of from 15 to 45 wt %.

21. The thermoplastic molding composition according to claim 1, wherein component E comprises glass fibers, and is present in an amount of from 20 to 40 wt %.

Description

EXAMPLES

[0373] The following components were used: [0374] PA1: Polyamide-66 having a viscosity number of 150 ml/g, measured on a 0.5% strength by weight solution in 96% strength by weight of sulfuric acid at 25° C. to ISO 307, melting point: 260° C. (Ultramid® A27 from BASF SE) [0375] PA2: Polyamide-6 having a viscosity number of 150 ml/g, measured on a 0.5% strength by weight solution in 96% strength by weight of sulfuric acid at 25° C. to ISO 307, melting point: 220° C. (Ultramid® B27 from BASF SE) [0376] GF: Standard E glass fiber, NEG T249H [0377] Lubricant: Ethylene bis stearamide (EBS) from Lonza Cologne GmbH [0378] Stabilizer 1: Cuprous iodide (CAS: 7681-65-4) [0379] Stabilizer 2: Potassium iodide (CAS: 7681-11-0) [0380] Stabilizer 3: OKAFLEXTM EM from OKA-Tec GmbH [0381] Stabilizer 4: Polyethylenimine (CAS: 9002-98-6), Lupasol® WF from BASF SE [0382] Colorant: Solvent Black 7 (CAS: 8005-02-5)

[0383] Preparation of the Granules

[0384] The natural-colored polyamide granulates were previously dried in a drying oven at 100° C. for four hours so that the moisture content was below 0.1% while all other ingredients were premixed in a tumble mixer for 10 minutes. In the next step, the dried polyamide granulates together with the dry blended ingredients were melt-extruded and granulated using a twin-screw extruder with a diameter of 25 mm and an L/D ratio of 44 at 300° C. cylinder temperature for PA66 and 280° C. respectively for PA6. The resulting granules were injection-molded on an injection molding machine at 300° C. melt temperature for PA66 and 280° C. melt temperature for PA6 to various specimen for the adjacent characterization.

[0385] Compositions and mechanical data for inventive (INV) and comparative (COMP) examples are listed in below Table 1.

[0386] Tensile modulus of elasticity, tensile stress at break and tensile strain at break are determined according to ISO 527. The Charpy (notched) impact strength is determined according to ISO 179-2/1eU and ISO 179-2/1eAf, respectively. Melting point and crystallization temperature are determined according to ISO 11357 using differential scanning calorimetry (DSC). All of the norms refer to the version valid in 2020.

[0387] Heat aging experiments were conducted in a standard laboratory oven at elevated temperatures and air as indicated in the tables below. Retention of tensile strength and elongation at break after heat aging in comparison with the value of the virgin specimens, the non-heat-aged control specimens were considered as being 100%.

TABLE-US-00003 TABLE 1 COMP1 COMP2 INV1 INV2 PA 1 0 0 0 50.75 PA 2 69.22 68.97 67.75 12 GF 30 30 30 35 Lubricant 0.2 0.2 0.2 0.2 Stabilizer 1 0.06 0.06 0 0 Stabilizer 2 0.22 0.22 0 0 Colorant 0.3 0.3 0.3 0.3 Stabilizer 3 0 0 1.5 1.5 Stabilizer 4 0 0.25 0.25 0.25 Mechanical properties (dry), 23° C. Modulus of elasticity (ISO 527) [MPa] 9357 9555 9749 11269 Tensile strength (ISO 527) [MPa] 173 180 179 199 Elongation at break (ISO 527) [%] 3.9 3.6 3.5 2.9 Impact strength (ISO 179/1eU) [kJ/m.sup.2] 96.4 83.8 87.3 83.1 Notched impact strength [kJ/m.sup.2] 12.8 10.4 12 11.1 Aging 150° C. Tensile strength (ISO 527) (3000 h) [MPa] 149 162 168 181 Retention of tensile strength after 3000 hours [%] 86 90 94 91 Aging 180° C. Tensile strength (ISO 527) (3000 h) [MPa] 141.0 153.0 153.0 162 Retention of tensile strength after 3000 hours [%] 81 85 85 81

[0388] The above examples illustrate that by employing the combination of stabilizer 4 (a polyethylenimine according to component B) and stabilizer 3 (according to component C), polyamide molding compositions can be obtained which show a high retention of tensile strength after prolonged heat-treatment. The high retention of tensile strength can be achieved without using CuI and Kl.

[0389] Superior results were obtained in comparison to a stabilizer system formed of CuI/Kl. When compared to a stabilizer system comprising CuI, Kl and polyethylenimine, the stabilized system according to the present invention leads to a similar tensile strength after heat aging at 180° C. and an improved tensile strength after heat aging at 150° C. The compositions according to the present invention INV1 and INV2 did not require the presence of CuI/Kl in order to achieve this effect.

[0390] When instead of polyamide 66, a polyamide 6 is employed as thermoplastic polymer, similar results were achieved, see Example INV2.

[0391] The above examples illustrate that by employing a combination of polyethylenimine homo- or copolymers with an aromatic amine co-stabilizer selected from secondary aryl amine compounds and/or condensation products of secondary aryl amines, aliphatic aldehydes and aliphatic ketones, the retention of the tensile strength, especially at an aging temperature of 150° C., can be significantly improved.