FLAME-RETARDANT POLYAMIDE COMPOSITION

Abstract

The invention relates to a flame-retardant, polyamide composition containing: as component A) 1 to 96 wt. % of one or more thermoplastic polyamides; as component B) 2 to 25 wt. % of a dialkylphosphinic acid salt of formula (I), where R1 and R2 are the same or different and represent linear, branched or cyclical C1-C18 alkyl, C6-C18 aryl, C7-C18 aryl alkyl and/or C7-C18 alkylaryl; M represents Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K and/or a protonated nitrogen base; m is 1 to 4; n is 1 to 4; as component C) 1 to 20 wt. % of a salt of phosphoric acid; as component D) 1 to 20 wt. % of one or more condensation products of melamine; as component E) 0 to 50 wt. % of a filler and/or reinforcing agent; as component F) 0 to 2 wt. % of a phosphite or phosphonite or mixtures thereof; and as component G) 0 to 2 wt. % of an ester or salt of long-chained aliphatic carboxylic acids (fatty acids) which typically have chain lengths of C14 to C40, the sum of the components always amounting to 100 wt. %. The invention also relates to the use of said composition.

Claims

1. A flame-retardant polyamide composition comprising as component A) 1% to 96% by weight of one or more thermoplastic polyamides, as component B) 2% to 25% by weight of a dialkylphosphinic salt of the formula (I) ##STR00008## wherein R.sup.1 and R.sup.2 are the same or different and are C.sub.1-C.sub.18-alkyl in linear, branched or cyclic form, C6-C18-aryl, C7-C18-arylalkyl and/or C7-C18-alkylaryl, M is Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K, a protonated nitrogen base or a mixture thereof; m is 1 to 4; n is 1 to 4; as component C) 1% to 20% by weight of a salt of phosphorous acid, as component D) 1% to 20% by weight of one or more condensation products of melamine, as component E) 0% to 50% by weight of filler, reinforcer or a mixture thereof, as component F) 0% to 2% by weight of phosphite or phosphonite or mixtures thereof, and as component G) 0% to 2% by weight of an ester or salt of long-chain aliphatic carboxylic acids having a chain length of C.sub.14 to C.sub.40, where the sum total of the components is always 100% by weight.

2. The flame-retardant polyamide composition as claimed in claim 1, comprising 15% to 89.9% by weight of component A), 5% to 20% by weight of component B), 2% to 10% by weight of component C), 2% to 10% by weight of component D), 1% to 50% by weight of component E), 0% to 2% by weight of component F) and 0.1% to 1% by weight of component G).

3. The flame-retardant polyamide composition as claimed in claim 1, comprising 15% to 75.8% by weight of component A), 5% to 20% by weight of component B), 2% to 10% by weight of component C), 2% to 10% by weight of component D), 15% to 35% by weight of component E), 0.1% to 1% by weight of component F) and 0.1% to 1% by weight of component G).

4. The flame-retardant polyamide composition as claimed in claim 1, comprising 35% to 65.8% by weight of component A), 5% to 20% by weight of component B), 2% to 7% by weight of component C), 2% to 7% by weight of component D), 25% to 35% by weight of component E), 0.1% to 0.5% by weight of component F) and 0.1% to 0.5% by weight of component G).

5. The flame-retardant polyamide composition as claimed in claim 1, comprising 35% to 96% by weight of component A), 2% to 25% by weight of component B), 1% to 20% by weight of component C), 1% to 20% by weight of component D), 0% to 50% by weight of component E), 0% to 2% by weight of component F) and 0% to 2% by weight of component G).

6. The flame-retardant polyamide composition as claimed in claim 1, having a comparative tracking index (CTI) of greater than 500 volts, measured according to International Electrotechnical Commission Standard IEC 60112/3.

7. The flame-retardant polyamide composition as claimed in claim 1, having a V-0 assessment according to UL-94 at a specimen thickness of 3.2 mm to 0.4 mm.

8. The flame-retardant polyamide composition as claimed in claim 1, having a glow wire flammability index (GWFI) according to IEC 60695-2-12 of 850° C. or more at a specimen thickness of 0.4 to 3 mm.

9. The flame-retardant polyamide composition as claimed in claim 1, having a glow wire ignition temperature index (GWIT) according to IEC 60695-2-13 of 750° C. or more at a specimen thickness of 0.4 to 3 mm.

10. The flame-retardant polyamide composition as claimed in claim 1, wherein the polyamide (PA) is selected from the group consisting of PA 6, PA 6,6, PA 4,6, PA 12, PA 6,10, PA 6T/66, PA 6T/6, PA 4T, PA 9T, PA 10T, polyamide copolymers, polyamide blends, and combinations thereof.

11. The flame-retardant polyamide composition as claimed in claim 1, wherein component A) is nylon-6,6 or copolymers or polymer blends of nylon-6,6 and nylon-6.

12. The flame-retardant polyamide composition as claimed in claim 1, wherein component A) is a polyamide PA 6T/66, PA 6T/6, PA 4T, PA 9T, PA 10T or a mixture thereof.

13. The flame-retardant polyamide composition as claimed in claim 1, wherein component D) comprises melam, melem, melon or a mixture thereof.

14. The flame-retardant polyamide composition as claimed in claim 1, wherein component D) is melem.

15. The flame-retardant polyamide composition as claimed in claim 1, wherein, in component B), R.sup.1 and R.sup.2 are the same or different and are methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, phenyl or a mixture thereof.

16. The flame-retardant polyamide composition as claimed in claim 1, wherein the salt of phosphorous acid, component C, conforms to the formula (II)
[HP(═O)O.sub.2].sup.2−M.sup.m+  (II) wherein M is Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K or a mixture thereof.

17. The flame-retardant polyamide composition as claimed in one claim 1, wherein the salt of phosphorous acid, component C) is aluminum phosphite Al(H.sub.2PO.sub.3).sub.3, secondary aluminum phosphite Al.sub.2(HPO.sub.3).sub.3, aluminum phosphite tetrahydrate Al.sub.2(HPO.sub.3).sub.3*4 aq, aluminum phosphonate, basic aluminum phosphite Al(OH)(H.sub.2PO.sub.3).sub.2*2 aq, Al.sub.7(HPO.sub.3).sub.9(OH).sub.6(1,6-hexanediamine).sub.1.5*12H.sub.2O, Al.sub.2(HPO.sub.3).sub.3*xAl.sub.2O.sub.3*nH.sub.2O with x=1−2.27 and n=1-5, Al.sub.4H.sub.6P.sub.16O.sub.18 or a mixture thereof.

18. The flame-retardant polyamide composition as claimed in claim 1, wherein the salt of phosphorous acid comprises aluminum phosphites of the formulae (Ill), (IV), (V) wherein
Al.sub.2(HPO.sub.3).sub.3x(H.sub.2O).sub.q  Formula (III): and q is o to 4;
Al.sub.2.00M.sub.z(HPO.sub.3).sub.y(OH).sub.vx(H.sub.2O).sub.w  Formula (IV) and M are alkali metal ions, z is 0.01 to 1.5, y is 2.63 to 3.5, v is 0 to 2 and w is 0 to 4;
Al.sub.2.00(HPO.sub.3).sub.u(H.sub.2PO.sub.3).sub.tx(H.sub.2O).sub.s  Formula (V) and u is 2 to 2.99 and t is 2 to 0.01 and s is 0 to 4, comprises mixtures of aluminum phosphite of the formula (III) with sparingly soluble aluminum salts and nitrogen-free extraneous ions, mixtures of aluminum phosphite of the formula (V) with aluminum salts, mixtures of aluminum phosphite of the formulae (III), (IV), (V) or a mixture thereof with aluminum phosphite [Al(H.sub.2PO.sub.3).sub.3], with secondary aluminum phosphite [Al.sub.2(HPO.sub.3).sub.3], with basic aluminum phosphite [Al(OH)(H.sub.2PO.sub.3).sub.2*2 aq], with aluminum phosphite tetrahydrate [Al.sub.2(HPO.sub.3).sub.3*4 aq], with aluminum phosphonate, with Al.sub.7(HPO.sub.3).sub.9(OH).sub.6(1,6-hexanediamine).sub.1.5*12H.sub.2O, with Al.sub.2(HPO.sub.3).sub.3*xAl.sub.2O.sub.3*nH.sub.2O with x=1-2.27 and n=1-50, with Al.sub.4H.sub.6P.sub.16O.sub.18 or a mixture thereof.

19. The flame-retardant polyamide composition as claimed in claim 1, wherein component C) has an average particle size of 0.2 to 100 μm.

20. The flame-retardant polyamide composition as claimed in claim 1, wherein the reinforcing filler or reinforce, component E), comprises glass fibers.

21. The flame-retardant polyamide composition as claimed in claim 1, wherein the phosphonites, component F) are those of the general structure
R—[P(OR.sup.5).sub.2].sub.m  (VI) wherein R is a mono- or polyvalent aliphatic, aromatic or heteroaromatic organic radical and R.sup.5 is a compound of the structure (VII) ##STR00009## or the two R.sup.5 radicals form a bridging group of the structure (VIII) ##STR00010## wherein A is a direct bond, O, S, C.sub.1-18-alkylene (linear or branched), C.sub.1-18-alkylidene, linear or branched, wherein R.sup.6 is independently C.sub.1-12-alkyl (linear or branched), C.sub.1-12-alkoxy, C.sub.5-12-cycloalkyl or a mixture thereof and n is 0 to 5 and m is 1 to 4.

22. The flame-retardant polyamide composition as claimed in claim 1, wherein component G) comprises alkali metal, alkaline earth metal, aluminum and/or zinc salts of long-chain fatty acids having 14 to 40 carbon atoms and/or reaction products of long-chain fatty acids having 14 to 40 carbon atoms with polyhydric alcohols such as ethylene glycol, glycerol, trimethylolpropane, pentaerythritol or a mixture thereof.

23. The flame-retardant polyamide composition as claimed in claim 1, further comprises telomers and wherein the telomers are ethylbutylphosphinic acid, dibutylphosphinic acid, ethylhexylphosphinic acid, butylhexylphosphinic acid, ethyloctylphosphinic acid, sec-butylethylphosphinic acid, (1-ethylbutyl)butylphosphinic acid, ethyl(1-methylpentyl)phosphinic acid, di-sec-butylphosphinic acid (di-1-methylpropylphosphinic acid), propyl(hexyl)phosphinic acid, dihexylphosphinic acid, hexyl(nonyl)phosphinic acid, dinonylphosphinic acid, salts thereof with the metals Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K or a mixture thereof.

24. A three-dimensional article comprising the composition as claimed in claim 1, comprising shaped bodies, injection moldings, extrusion compounds or extrudates.

25. A three dimensional article comprising a flame-retardant polyamide composition as claimed in claim 1, wherein the three dimensional article is selected from the group consisting of plug connectors, current-bearing components in power distributors, circuit boards, potting compounds, plug connectors, circuit breakers, lamp housings, capacitor housings, coil elements and ventilators for grounding contacts, plugs, printed circuit boards, housings for plugs, cables, flexible circuit boards, charging cables for mobile phones, motor covers and textile coatings.

Description

EXAMPLES

1. Components Used

[0158] Commercial polyamides (component A)):

Nylon-6,6 (PA 6,6-GR): Ultramid® A27 (from BASF SE, Germany)
Nylon-6: Ultramid® B27 (from BASF SE, Germany)
Nylon-6T/6,6: Vestamid HTplus M1000 (from Evonik, Germany)
Nylon-10T: Vestamid HTplus M3000 (from Evonik, Germany)

[0159] Component E): PPG HP 3610 glass fibers with diameter 10 μm and length 4.5 mm (from PPG, the Netherlands)

[0160] Flame retardant (component B)):

aluminum salt of diethylphosphinic acid, referred to hereinafter as DEPAL

[0161] Flame retardant (component C)):

aluminum salt of phosphorous acid, referred to hereinafter as PHOPAL

[0162] Flame retardant (component D)):

Delacal 360 (melam)
Delacal 420 (melem)
Delacal 500 (melon), all from Delamin Ltd., UK

[0163] Comparison: MPP, melamine polyphosphate, Melapur® 200/70, from BASF AG, Germany

[0164] Phosphonites (component F)): Sandostab® P-EPQ, from Clariant GmbH, Germany

[0165] Wax components (component G)):

Licowax® E, from Clariant Produkte (Deutschland) GmbH, Germany (esters of montan wax acid)

2. Production, Processing and Testing of Flame-Retardant Polyamide Molding Compounds

[0166] The flame retardant components were mixed with the phosphonite, the lubricants and stabilizers in the ratio specified in the table and incorporated via the side intake of a twin-screw extruder (Leistritz ZSE 27/44D) into PA 6,6 at temperatures of 260 to 310° C., and into PA 6 at 250-275° C. The glass fibers were added via a second side intake. The homogenized polymer strand was drawn off, cooled in a water bath and then pelletized.

After sufficient drying, the molding compounds were processed to test specimens on an injection molding machine (Arburg 320 C Allrounder) at melt temperatures of 250 to 300° C., and tested and classified for flame retardancy using the UL 94 test (Underwriter Laboratories).

[0167] The UL 94 fire classifications are as follows: [0168] V-0: afterflame time never longer than 10 sec, total of afterflame times for 10 flame applications not more than 50 sec, no flaming drops, no complete consumption of the specimen, afterglow time for specimens never longer than 30 sec after end of flame application. [0169] V-1: afterflame time never longer than 30 sec after end of flame application, total of afterflame times for 10 flame applications not more than 250 sec, afterglow time for specimens never longer than 60 sec after end of flame application, other criteria as for V-0. [0170] V-2: cotton indicator ignited by flaming drops, other criteria as for V-1. not classifiable (ncl): does not comply with fire classification V-2.

[0171] Glow wire resistance was determined using the GWFI (glow wire flammability index) glow wire test according to IEC 60695-2-12 and the glow wire ignitability test GWIT (glow wire ignition temperature) according to IEC 60695-2-13. In the GWFI test, using three test specimens (for example using plates of geometry 60×60×1.5 mm), with the aid of a glow wire, at temperatures between 550 and 960° C., the maximum temperature at which an afterflame time of 30 seconds is not exceeded and the sample does not give off burning drops is determined. In the GWIT test, in a comparable measurement procedure, the glow wire ignition temperature 25 K higher (30 K between 900° C. and 960° C.) than the maximum glow wire temperature that does not lead to ignition in 3 successive tests even during the contact time of the glow wire is reported. Ignition is regarded here as a flame having a burning time of 5 seconds or more.

[0172] The flowability of the molding compositions was determined by finding the melt volume flow rate (MVR) at 275° C./2.16 kg. Higher MVR values mean better flowability in the injection molding process. However, a significant rise in the MVR value can also suggest polymer degradation.

[0173] All tests in the respective series, unless stated otherwise, were performed under identical conditions (temperature programs, screw geometry, injection molding parameters, etc.) for comparability.

[0174] The results in which the flame retardant-stabilizer mixture according to the invention was used are listed in examples 11-13. All amounts are reported as % by weight and are based on the polymer molding compound including the flame retardants, additives and reinforcers.

TABLE-US-00001 TABLE 1 N 6,6 GF 30 test results. C1-C4 are comparative examples, I1 to I3 are polyamide moulding compound of the invention C1 C2 C3 C4 I1 I2 I3 A: Nylon-6,6 [% by wt.] 49.55 49.55 49.55 39.55 39.55 49.30 49.30 A: Nylon-6 [% by wt.] 10 10 E: HP3610 glass fibers [% by wt.] 30 30 30 30 30 30 30 B: DEPAL [% by wt.] 20 17 15 10 14 12 12 C: PHOPAL [% by wt.] 3 3 3 3 MPP [% by wt.] 10 D1: Delacal 360 [% by wt.] 5 3 5 D2: Delacal 420 [% by wt.] 5 G: Licowax E [% by wt.] 0.25 0.25 0.25 0.25 0.25 0.25 0.25 F: P-EPQ [% by wt.] 0.20 0.20 0.20 0.20 0.20 0.20 0.20 Test results UL 94 at thickness 0.4 mm V-1 V-0 V-1 V-0 V-0 V-0 V-0 GWFI at thickness 0.4 mm [° C.] 850 960 850 960 960 960 960 MVR 275° C./2.16 kg 4 5 6 17 9 8 10 GWIT at thickness 0.75 mm [° C.] 700 725 725 775 800 800 775 Color of the specimens** yellow yellow white white white white white Exudation* none none none marked none none none CTI [volts] 600 600 550 550 600 600 600 Impact resistance [kJ/m.sup.2] 60 63 58 61 68 71 69 Notched impact resistance [kJ/m.sup.2] 12 11 11 10 14 14 12 *14 days 100% humidity 70° C. **yellow: yellowness index >20

[0175] Only by virtue of the inventive combination of polyamide, glass fibers, DEPAL, PHOPAL and melem or melam are polyamide molding compounds obtained that attain the UL 94 V-0 fire class at 0.4 mm and simultaneously have a GWIT greater than 775° C. and CTI 600 volts, impact resistance greater than 65 kJ/m.sup.2, notched impact resistance greater than 10 kJ/m.sup.2, and do not exhibit any coloring (yellowness index <20) or any exudation. Moreover, only these compositions of the invention have the desired whiteness. The use of DEPAL without PHOPAL (C1) does not achieve V-0; the combination of DEPAL with MPP (C4) does achieve V-0 and GWIT 775° C., but the polyamide molding compound shows coloring and exudation. A CTI of 600 V is likewise not attained. The combination of DEPAL with PHOPAL does not attain GWIT >=775° C.; the combination of DEPAL with melam (C3) does not fulfill UL 94 V-0 and GWIT 775° C.

TABLE-US-00002 TABLE 2 PA 6 GF 30 test results. C5-C7 are comparative examples, I4 and I5 are polyamide moulding compound of the invention C5 C6 C7 I4 I5 A: Nylon-6 [% by wt.] 49.55 49.55 49.55 49.55 49.55 E: HP3610 glass fibers [% by wt.] 30 30 30 30 30 B: DEPAL [% by wt.] 20 12 17 12 14 C: PHOPAL [% by wt.] 3 3 3 MPP [% by wt.] 8 D2: Delacal 420 [% by wt.] 5 3 G: Licowax E [% by wt.] 0.25 0.25 0.25 0.25 0.25 F: P-EPQ [% by wt.] 0.20 0.20 0.20 0.20 0.20 Test results UL 94 at thickness 0.4 mm V-1 V-0 V-0 V-0 V-0 GWIT at thickness 0.75 mm [° C.] 700 775 725 800 775 MVR 250° C./2.16 kg 5 12 5 10 9 Exudation* none marked none none none CTI [volts] 600 550 600 600 600 Impact resistance [kJ/m.sup.2] 61 59 62 67 65 Notched impact resistance [kJ/m.sup.2] 11 9.8 10 12 12 *14 days, 100% humidity, 70° C.

[0176] The experiments in nylon-6 show a similar picture: only the inventive combination of nylon-6 with glass fibers, DEPAL, PHOPAL and melem gives molding compounds which simultaneously have UL 94 V-0 at 0.4 mm, GWIT >=775° C., CTI 600 V, no exudation, good flowability and good mechanical values.

TABLE-US-00003 TABLE 3 PA 10T GF 30 test results. C8-C10 are comparative examples, I6 and I7 are polyamide moulding compound of the invention C8 C9 C10 I6 I7 A: Nylon-10T [% by wt.] 49.55 49.55 49.55 49.55 49.55 E: HP3610 glass fibers [% by wt.] 30 30 30 30 30 B: DEPAL [% by wt.] 20 12 17 12 14 C: PHOPAL [% by wt.] 3 3 3 D2: Delacal 420 [% by wt.] 8 5 3 G: Licowax E [% by wt.] 0.25 0.25 0.25 0.25 0.25 F: P-EPQ [% by wt.] 0.20 0.20 0.20 0.20 0.20 Test results UL 94 at thickness 0.4 mm V-1 V-1 V-0 V-0 V-0 GWIT at thickness 0.75 mm [° C.] 750 750 750 800 825 Exudation* none marked none none none CTI [volts] 600 550 600 600 600 Impact resistance [kJ/m.sup.2] 70 61 61 71 68 Notched impact resistance [kJ/m.sup.2] 9 8 9 8 9 *14 days, 100% humidity, 70° C.

[0177] In nylon-10T as well, only the inventive combination of polyamide with glass fibers, DEPAL, PHOPAL and melem gives molding compounds which simultaneously have UL 94 V-0 at 0 4 mm, GWIT >=775° C., CTI 600 V, no exudation and good mechanical values. The combination of DEPAL and MPP cannot be processed in PA 10T.

TABLE-US-00004 TABLE 4 PA 6T/66 GF 30 test results. C11-C13 are comparative examples, I8 and I9 are polyamide moulding compound of the invention C11 C12 C13 I8 I9 A: Nylon-6T/66 [% by wt.] 54.55 54.55 54.55 54.55 54.55 E: HP3610 glass fibers [% by wt.] 30 30 30 30 30 B: DEPAL [% by wt.] 15 10 12 10 8 C: PHOPAL [% by wt.] 3 2 2 D2: Delacal 500 [% by wt.] 5 3 5 G: Licowax E [% by wt.] 0.25 0.25 0.25 0.25 0.25 F: P-EPQ [% by wt.] 0.20 0.20 0.20 0.20 0.20 Test results UL 94 at thickness 0.4 mm V-0 V-1 V-0 V-0 V-0 GWIT at thickness 0.75 mm [° C.] 750 750 750 825 800 Exudation* none none none none none CTI [volts] 600 600 600 600 600 Impact resistance [kJ/m.sup.2] 62 58 61 63 62 Notched impact resistance [kJ/m.sup.2] 7 7 8 8 7 *14 days, 100% humidity, 70° C.

[0178] In nylon-6T/6,6, the inventive combination of polyamide with glass fibers, DEPAL, PHOPAL and melon gives molding compounds which simultaneously have UL 94 V-0 at 0 4 mm, GWIT >=775° C., CTI 600 V, no exudation and good mechanical values. The combination of DEPAL and MPP cannot be processed in PA 6T/66 either.

[0179] Overall, only the combinations of the invention attain all the parameters to be fulfilled.