Flame-retardant polyamide compositions with a high glow wire ignition temperature and use thereof

Abstract

A flame-retardant polyamide composition can be prepared with a glow wire ignition temperature of not less than 775° C. Such a composition can include a polyamide having a melting point of not more than 290° C. as component A, fillers and/or reinforcers as component B, a phosphinic salt of the formula (I) as component C, a compound selected from the group of the Al, Fe, TiO.sub.p and Zn salts of ethylbutylphosphinic acid, of dibutylphosphinic acid, of ethylhexylphosphinic acid, of butylhexylphosphinic acid and/or of dihexylphosphinic acid as component D, a phosphonic salt of the formula (II) as component E, and a melamine polyphosphate having an average degree of condensation of 2 to 200 as component F. Additional components can be included in the composition.

Claims

1. A flame-retardant polyamide composition, comprising: 25% to 75% by weight of polyamide having a melting point of not more than 290° C. as component A, wherein the component A comprises polymer mixtures of nylon-6,6 and nylon-6; 20% to 40% by weight of fillers and/or reinforcers as component B; 5% to 10% by weight of phosphinic salt of the formula (I) as component C ##STR00004## in which R.sub.1 and R2 are ethyl, M is Al, Fe, TiO.sub.p or Zn, m is 2 to 3, and
p=(4−m)/2; 0.05% to 1.5% by weight of a compound selected from the group of the Al, Fe, TiO.sub.p and Zn salts of ethylbutylphosphinic acid, of dibutylphosphinic acid, of ethylhexylphosphinic acid, of butylhexylphosphinic acid and/or of dihexylphosphinic acid as component D, wherein p=(4−m) / 2 and m is 2 to 3; 0.01% to 0.6% by weight of a phosphonic salt of the formula II as component E ##STR00005## in which R.sub.3 is ethyl, Met is Al, Fe, TiO.sub.q or Zn, n is 2 to 3, and
q=(4−n)/2; 2% to 10% by weight of melamine polyphosphate having an average degree of condensation of 20 to 200 as component F; and 0.02% to 2% by weight of an inorganic phosphite phosphonate as component G, wherein the flame-retardant polyamide composition has a glow wire ignition temperature (GWIT) according to IEC-60695-2-13 of not less than 800 ° C. at thickness 0.75-3 mm.

2. The flame-retardant polyamide composition as claimed in claim 1, wherein M and Met are Al, m and n are 3, and component D is an aluminum salt.

3. The flame-retardant polyamide composition as claimed in claim 1, wherein the inorganic phosphonate as component G is a compound of the formula (III) ##STR00006## in which Me is Fe, TiO.sub.r, Zn or Al, o is 2 to 3, and
r=(4−o)/2, where the compound of the formula III is present in an amount of 0.02% to 5% by weight, based on the total amount of the polyamide composition.

4. The flame-retardant polyamide composition as claimed in claim 1, wherein the flame-retardant polyamide composition has a comparative tracking index measured by International Electrotechnical Commission Standard IEC-60112/3 of not less than 500 volts.

5. The flame-retardant polyamide composition as claimed in claim 1, wherein the flame-retardant polyamide composition attains a V-0 assessment according to UL94 from thickness 3.2 mm to 0.4 mm.

6. The flame-retardant polyamide composition as claimed in claim 1, wherein the flame-retardant polyamide composition has a glow wire flammability according to IEC-60695-2-12 of not less than 960° C. at thickness 0.75-3 mm.

7. The flame-retardant polyamide composition as claimed in claim 1, wherein component A consists to an extent of at least 75% by weight of nylon-6,6 and to an extent of at most 25% by weight of nylon-6.

8. The flame-retardant polyamide composition as claimed in claim 1, wherein glass fibers are used as component B.

9. The flame-retardant polyamide composition as claimed in claim 1, wherein components C, D, E and F are in particulate form, where the median particle size d.sub.50 of these components is 1 to 100 μm.

10. The flame-retardant polyamide composition as claimed in claim 1, wherein the average degree of condensation of the melamine polyphosphate is 40 to 150.

11. The flame-retardant polyamide composition as claimed in claim 1, wherein the melamine polyphosphate has a breakdown temperature of not less than 320° C.

12. The flame-retardant polyamide composition as claimed in claim 1, which comprises further additives as component H, where the further additives are selected from the group consisting of antioxidants, UV stabilizers, gamma ray stabilizers, hydrolysis stabilizers, costabilizers for antioxidants, antistats, emulsifiers, nucleating agents, plasticizers, processing auxiliaries, impact modifiers, dyes, pigments and/or further flame retardants other than components C, D, E, F and G.

13. The flame-retardant polyamide composition as claimed in claim 1 in the form of fibers, films or shaped bodies.

Description

EXAMPLES 1-5, 1a, 1b, 5a AND COMPARATIVE EXAMPLES C1-C5 WITH PA 6,6

(1) The results of the experiments with PA 6,6 molding compounds are listed in the examples adduced in the table which follows. All amounts are reported as % by weight and are based on the polyamide molding compound including the flame retardants and reinforcers.

(2) TABLE-US-00001 TABLE 1 PA 6,6 GF 30 Test results Example No. 1 2 3 4 5 1a 1b 5a C1 C2 C3 C4 C5 A: Nylon-6,6 53  53  53  53 53 53 50  50  53 53  58  53  53 B: HP3610 glass 30  30  30  30 30 30 30  30  30 30  30  30  30 fibers C + D + E: FM 1 12 — — — — 8 16 — — — — — — C + D + E: FM 2 —  12 — — 10 — —  10 — 12  12  17 — C + D + E: FM 3 — —  12 — — — — — — — — — — C + D + E: FM 4 — — —  12 — — — — — — — — — C: FM 5 — — — — — — — — — — — —  12 C + E: FM 6 — — — — — — — —  12 — — — — G: FM 7 — — — — 0.02 — —  5 — — — — — F: FM 8 5  5  5  5 5 9 4  5  5 — — —  5 Comparison: FM 9 — — — — — — — — —  5 — — — UL 94 0.4 mm/time C-0/25 C-0/20 C-0/25 C-0/40 C-0/10 C-0/28 C-0/26 C-0/10 C-0/45 n.d. C-2/99 C-1/85 C-0/49 [sec] GWIT [ ° C.] 775 775 775 800 775 775 775 775 725 n.d. 700 700 725 GWFI [ ° C.] 960 960 960 960 960 960 960 960 960 n.d. 850 900 960 CTI [volts] 600 600 600 600 600 600 600 600 500 n.d. 600 600 500 (1-5, 1a, 1b and 5a inventive; C1-C5 comparisons; n.d. = not determined)

(3) The inventive polyamide compositions of examples 1 to 5, 1a, 1b and 5a are molding compounds which attain the UL94 V-0 fire class at 0.4 mm, simultaneously have CTI 600 volts or 550 volts, GWFI 960° C. and GWIT 775° C. The addition of component G in examples 5 and 5a leads to another improvement in flame retardancy, expressed by a reduced afterflame time.

(4) The omission of component D in comparative example C1 resulted not only in a prolonged afterflame time but also in a reduced CTI value compared to examples 1-4.

(5) The replacement of component F by a component having a lower degree of condensation in comparative example C2 had the result that the polyamide strand foamed in the course of production and no measurements could be undertaken.

(6) The omission of component F in comparative example C3 resulted not only in a deterioration of the fire protection class compared to example 2 but also in reduced GWFI and GWIT values.

(7) In comparative example C4, an improvement in fire protection class compared to example C3 was achieved by increasing the concentration of components C, D and E. However, this polyamide composition still exhibited a lower fire protection class compared to example 2 and reduced GWFI and GWIT values.

(8) The omission of components D and E in comparative example C5 resulted not only in a prolonged afterflame time but also in a reduced value compared to examples 1-4.

EXAMPLES 6-10 AND COMPARATIVE EXAMPLES C6-C10 WITH PA 6,6/PA 6

(9) The results of the experiments with PA 6/PA 6,6 molding compounds are listed in the examples adduced in the table which follows. All amounts are reported as % by weight and are based on the polyamide molding compound including the flame retardants and reinforcers.

(10) TABLE-US-00002 TABLE 2 PA 6/PA 6,6 GF 30 Test results Example No. 6 7 8 9 10 C6 C7 C8 C9 C10 A: Nylon-6,6 38  38 38 38 38 38 38 43 38 38 A: Nylon 6 15  15 15 15 15 15 15 15 15 15 B: HP3610 glass fibers 30  30 30 30 30 30 30 30 30 30 C + D + E: FM 1 12 — — — — — — — — — C + D + E: FM 2 —  12 — — 10 — 12 12 17 — C + D + E: FM 3 — — 12 — — — — — — — C + D + E: FM 4 — — — 12 — — — — — — C: FM 5 — — — — — — — — — 12 C + E: FM 6 — — — — — 12 — — — — H: FM 7 — — — —  2 — — — — — F: FM 8 5  5  5  5  5  5 — — —  5 Comparison: FM 9 — — — — — —  5 — — — UL 94 0.4 mm/time [sec] C-0/29 C-0/23 C-0/44 C-0/28 C-0/14 C-0/47 n.d. C-2/99 C-1/87 C-0/49 GWIT [ ° C.] 775 775 775  775  800  725  n.d. 675  700  725  GWFI [ ° C.] 960 960 960  960  960  960  n.d. 850  900  960  CTI [volts] 600 600 600  600  600  500  n.d. 600  600  500  (6-10 inventive; C6-C10 comparisons; n.d. = not determined)

(11) The inventive polyamide compositions of examples 6 to 10 are molding compounds which attain the UL94 V-0 fire class at 0.4 mm, simultaneously have CTI 600 volts or 550 volts, GWFI 960° C. and GWIT 775° C. The addition of component G in example 10 leads to another improvement in flame retardancy, expressed by a reduced afterflame time.

(12) The omission of component D in comparative example C6 resulted not only in a prolonged afterflame time but also in a reduced CTI value compared to examples 6-9.

(13) The replacement of component F by a component having a lower degree of condensation in comparative example C7 had the result that the polyamide strand foamed in the course of production and no measurements could be undertaken.

(14) The omission of component F in comparative example C8 resulted not only in a deterioration of the fire protection class compared to example 7 but also in reduced GWFI and GWIT values.

(15) In comparative example C9, an improvement in fire protection class compared to example C8 was achieved by increasing the concentration of components C, D and E. However, this polyamide composition still exhibited a lower fire protection class compared to example 7 and reduced GWFI and GWIT values.

(16) The omission of components D and E in comparative example 010 resulted not only in a prolonged afterflame time but also in a reduced CTI value compared to examples 6-9.

COMPARATIVE EXAMPLES C11-C16 WITH PA 6T/6,6

(17) The results of the experiments with PA 6T/6,6 molding compounds are listed in the examples adduced in the table which follows. All amounts are reported as % by weight and are based on the polyamide molding compound including the flame retardants and reinforcers.

(18) TABLE-US-00003 TABLE 3 PA 6T/6,6 GF 30 test results Example No. C11 C12 C13 C14 C15 C16 A: Nylon-6T/6,6   52.8   52.8   52.8   52.8   52.8   52.8 B: HP3610 glass fibers 30 30 30 30 30 30 C + D + E: FM 1 12 — — — — — C + D + E: FM 2 — 12 — — 10 — C + D + E: FM 3 — — 12 — — — C + D + E: FM 4 — — — 12 — — C: FM 5 — — — — — 12 C + E: FM 6 — — I: FM 7 — — — —  2 — F: FM 8  5  5  5  5  5  5 Comparison: FM 9 — — — — — — UL 94 0.4 mm/time [sec.] n.d. n.d. n.d. n.d. n.d. n.d. GWIT [° C.] n.d. n.d. n.d. n.d. n.d. n.d. GWIF [° C.] n.d. n.d. n.d. n.d. n.d. n.d. CTI [volts] n.d. n.d. n.d. n.d. n.d. n.d. (n.d. = not determined)

(19) None of the PA molding compounds from comparative examples 011-C16 produced test specimens since the PA molding compounds were found not to be workable. The polyamide strands foamed up in the course of production and it was not possible to produce any test specimens suitable for the measurements.