Fire-retardant polyamides comprising PVP

Abstract

A thermoplastic molding composition is disclosed. The thermoplastic molding composition includes A) from 20 to 96.9% by weight of a thermoplastic polyamide, B) from 1 to 20% by weight of an inorganic phosphinate salt, C) from 1 to 15% by weight of an organic phosphinate salt, D) from 1 to 15% by weight of melamine cyanurate, E) from 0.1 to 10% by weight of a polyvinylpyrrolidone homopolymer, and F) from 0 to 50% by weight of other additives. The total of the percentages by weight of A) to F) is 100%.

Claims

1. A thermoplastic molding composition comprising A) from 20 to 96.9% by weight of a thermoplastic polyamide, B) from 1 to 20% by weight of an inorganic phosphinate salt, C) from 1 to 15% by weight of an organic phosphinate salt, D) from 1 to 15% by weight of melamine cyanurate, E) from 0.1 to 10% by weight of a polyvinylpyrrolidone homopolymer, F) from 0 to 50% by weight of other additives, where the total of percentages by weight of A) to F) is 100% and component E) a number average molar mass Mn measured by GPC of from 1,000 to 500,000 g/mol, wherein the GPC is carried out with PVP standard and water/methanol (80/20) with 0.01 mol/L of phosphate buffer at pH 7.14 as eluent.

2. The thermoplastic molding composition according to claim 1, comprising: A) from 30 to 92.5% by weight, B) from 5 to 20% by weight, C) from 1 to 10% by weight, D) from 1 to 10% by weight, E) from 0.5 to 8% by weight, F) from 0 to 40% by weight, where the total of the percentages by weight of A) to F) is 100%.

3. The thermoplastic molding composition according to claim 1, in which component B) is a metal salt of an inorganic phosphinic acid of formula (I): ##STR00009## in which R.sup.1 and R.sup.2 are hydrogen and M=Mg, Ca, Al, Zn and m=from 1 to 3.

4. The thermoplastic molding composition according to claim 1, comprising aluminum hypophosphite as component B).

5. The thermoplastic molding composition according to claim 1, in which component C) is an organic phosphinate salt of formula (II): ##STR00010## in which R.sup.1 and R.sup.2 are identical or different and are C.sub.1-C.sub.6-alkyl, linear or branched and/or aryl; and M=Mg, Ca, Al, Ti, Zn, Fe, Li, Na, K or a protonated nitrogen base and m is from 1 to 5.

6. The thermoplastic molding composition according to claim 5, in which component C) is an aluminum salt of a dialkylphosphinic acid of formula (II).

7. The thermoplastic molding composition according to claim 1, in which component E) is pulverulent.

8. The thermoplastic molding composition according to claim 1, in which component E) has a d.sub.50 value of from 40 to 180 μm, determined by means of laser scattering on powder.

9. A fiber, film or molding obtainable from the thermoplastic molding compositions according to claim 1.

Description

EXAMPLES

(1) The following components were used:

(2) Component A:

(3) Polyamide 6 with intrinsic viscosity IV 107 ml/g, measured on a 0.5% by weight solution in 96% by weight sulfuric acid at 25° C. in accordance with ISO 307 (Ultramid® B22 from BASF SE).

(4) Component B:

(5) Aluminum hypophosphite (Phoslite® IP-A from Italmatch Chemicals SPA).

(6) Component C:

(7) Aluminum salt of diethylphosphinic acid (Exolit® OP1230 from Clariant GmbH).

(8) Component D:

(9) Melamine cyanurate with average particle size ˜2.6 μm (Melapur® MC 25 from BASF SE).

(10) Component E/1V: for Comparison

(11) Ethylene-vinyl alcohol copolymer with 29% ethylene content (Soarnol® DT2904RB from Nippon Gohsei).

(12) Component E/2:

(13) Pulverulent polyvinylpyrrolidone homopolymer with number-average molecular weight Mn from 1500 to 2500 daltons (Luvitec® K17 from BASF SE).

(14) Component E/3:

(15) Pulverulent polyvinylpyrrolidone homopolymer with number-average molecular weight Mn from 11 000 to 18 000 daltons (Luvitec® K30 from BASF SE).

(16) Component E/4:

(17) Polyvinylpyrrolidone homopolymer with number-average molecular weight Mn from 300 000 to 400 000 daltons (Luvitec® K90 from BASF SE).

(18) Component F/1:

(19) Standard chopped glassfiber for polyamides, L=4.0 mm, D=10 μm.

(20) Component F/2 (PVP Premix):

(21) Formulations F1-F5 used the following further additives: 0.35% of 3,3′-bis(3,5-di-tert-butyl-4-hydroxyphenyl)-N,N′-hexamethylenedipropionamide (CAS No. 23128-74-7) as heat stabilizer and 0.4% of ethylenebisstearamide (CAS No. 110-30-5) as processing aid.

(22) Component F/2 (EvOH Premix):

(23) Formulation V1 used the following further additives: 0.35% of 3,3′-bis(3,5-di-tert-butyl-4-hydroxyphenyl)-N,N′-hexamethylenedipropionamide (CAS No. 23128-74-7) and 0.2% of ethylenebis(oxyethylene) bis(3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate) (CAS No. 36443-68-2) as heat stabilizers and 0.4% of ethylenebisstearamide (CAS No. 110-30-5) as processing aid.

(24) The sum of the proportions of components A) to F) in table 1 is 100% by weight. The constitutions of the molding compositions and the results of the tests can likewise be found in table 1.

(25) Production of Molding Compositions

(26) Appropriate plastics molding compositions were prepared by compounding. For this, the individual components were mixed at throughput 20 kg/h in a ZSK 26 (Berstorff) twin-screw extruder with a flat temperature profile at about 250-270° C., discharged in the form of strand, cooled until pelletizable and pelletized.

(27) The test samples for the tests listed in table 1 were injection-molded in an Arburg 420C injection-molding machine at melt temperature about 250-290° C. and mold temperature about 80° C.

(28) Flame retardancy of the molding compositions was determined by the UL 94 V method (Underwriters Laboratories Inc. Standard of Safety, “Test for Flammability of Plastic Materials for Parts in Devices and Appliances”, p. 14 to p. 18, Northbrook 1998).

(29) Glow-wire resistance was determined by the GWFI (glow-wire flammability index) glow-wire ignition test in accordance with DIN EN 60695-2-12 and the GWIT (glow-wire ignition temperature) glow-wire ignition test in accordance with DIN EN 60695-2-13.

(30) The GWFI test, carried out on 3 test samples (for example plaques measuring 60×60×1.0 mm or disks), used a glowing wire at temperatures of from 650 to 960° C. to determine the maximal temperature leading to no ignition during a time including the period of exposure to the glow-wire in 3 successive tests. The test sample was pressed by a force of 1 Newton for a period of 30 seconds against a heated glow-wire. The penetration depth of the glow-wire was restricted to 7 mm. The test is considered passed if the afterflame time of the test sample after removal of the glow-wire is less than 30 seconds and if tissue paper placed under the test sample does not ignite.

(31) The GWIT test, carried out on 3 test samples (for example plaques measuring 0×60×1.5 mm), used a glowing wire at temperatures of from 650 to 960° C. to determine the maximal temperature leading to no ignition during a time including the period of exposure to the glow-wire in 3 successive tests. The glow-wire ignition temperature stated was 25 K above the maximal temperature determined. The ignition criterion used here was a flame with flame time >5 sec.

(32) The molding compositions (for example plaques measuring 60×60×1.5 mm) were heat-aged in a convection oven at the respective stated temperature.

(33) Color was measured in accordance with DIN 53236, R45/0° illumination, in accordance with CIE L*a*b.

(34) The data in table 1 show that the compositions Inv1-Inv5 exhibit better values than the prior art (Comp. 1) both in respect of flame retardancy at low wall thicknesses (UL 94 V-2 at 0.4 mm) and in relation to thermal stability. The MVR results reveal that melt stability at prolonged residence times does not increase as sharply as for Comp. 1 after 20 min. Color measurement after/during heat-aging at 150° C. moreover shows that yellowing of the molding compositions of the invention proceeds less rapidly than in the prior art (smaller delta E values).

(35) The reduced stabilizes amount in V3 is mirrored in the reduced thermal ageing stability.

(36) TABLE-US-00001 TABLE 1 Constitutions and properties Comp. Comp. Comp. Component/Test method Inv1 Inv2 Inv3 Inv4 Inv5 1 2 3 A/1 45.25 44.25 43.25 43.25 43.25 44.55 46.25 44.75 B 11.3 11.3 11.3 11.3 11.3 11.3 11.3 11.3 C 5 5 5 5 5 5 5 5 D 6.7 6.7 6.7 6.7 6.7 6.7 6.7 6.7 E/1 1.5 1.5 E/2 1 2 3 E/3 3 E/4 3 F/1 30 30 30 30 30 30 30 30 F/2 0.75 0.75 0.75 0.75 0.75 0.75 0.75 F/3 0.95 Intrinsic viscosity in 113 111 110 120 135 113 122 112 H2SO4/cm3/g (ISO307) Tensile modulus of 12307 12411 12268 12494 12449 12063 11515 11926 elasticity/MPa (ISO 527) Tensile stress at 167 168 171 170 166 172 148 174 break/MPa (ISO 527) Tensile strain at 2.7 2.5 2.6 2.5 2.4 2.5 3.0 2.6 break/% (ISO 527) MVR 275° C./5 Kg 119 118 — 96 66 33 42 28 (ISO1133) MVR 275° C./5 Kg 98 101 — 66 66 78 — 64 (ISO1133) after 10 min MVR 275° C./5 Kg 67 75 — 67 45 >500 — 434 (ISO1133) after 20 min UL 94 V test (0.4 mm) V-2 V-2 V-2 V-2 V-2 n.c. n.c. n.c. UL 94 V test (0.8 mm) V-0 V-0 V-0 V-0 V-0 V-0 V-2 V-0 GWFI 960° C./1.5 mm passed passed passed passed passed passed passed passed GWIT max, 1.5 mm/° C. 825 825 825 825 825 875 825 850 GWIT 775° C./1.5 mm passed passed passed passed passed passed passed passed Tensile stress at break 119 124 122 95 after 500 h of heat-aging at 150° C./MPa (ISO 72 74 71 51 527)/% from initial value Color measurement after 18 21 32 36 24 h of heat-aging at 150° C./delta E (DIN 53236) Color measurement after 26 27 43 43 48 h of heat-aging at 150° C./delta E (DIN 53236)