FLAME RETARDANT MIXTURE FOR THERMOPLASTIC POLYMERS

Abstract

The invention relates to a flame retardant mixture for thermoplastic polymers, comprising as component A) 30% to 55% by weight of a zinc salt of a di-alkylphosphinic acid of the formula (I) in which R.sup.1 and R.sup.2 are the same or different and are C.sub.1-C.sub.18-alkyl linear, branched or cyclic, C.sub.6-C.sub.18-aryl, C.sub.7-C.sub.18-arylalkyl and/or C.sub.7-C.sub.18-alkylaryl, and M is zinc and m=1 to 2, as component B) 45% to 70% by weight of one or more reaction products of melamine with polyphosphoric acids and/or condensed melamine with polyphosphoric acids, as component C) 0% to 10% of at least one further inorganic flame retardant which is zinc borate, zinc stannate, zinc phosphate, zinc pyrophosphate, magnesium borate and/or calcium stannate, as component D) 0% to 20% by weight of one or more condensation products of melamine, as component E) 0% to 2% by weight of at least one phosphite or phosphinite or mixtures thereof and as component F) 0% to 2% by weight of at least one ester and/or salt of long chain aliphatic carboxylic acids (fatty acids) typically having chain lengths of C.sub.14 to C.sub.40, where the sum total of the components is always 100% by weight.

##STR00001##

Claims

1. A flame retardant mixture for thermoplastic polymers, comprising as component A) 30% to 55% by weight of a zinc salt of a dialkylphosphinic acid of the formula (I) ##STR00006## in which R.sup.1 and R.sup.2 are the same or different and are C.sub.1-C.sub.18-alkyl linear, branched or cyclic, C.sub.6-C.sub.18-aryl, C.sub.7-C.sub.18-arylalkyl and/or C.sub.7-C.sub.18-alkylaryl, and M is zinc and m=1 to 2, as component B) 45% to 70% by weight of one or more reaction products of melamine with polyphosphoric acids and/or condensed melamine with polyphosphoric acids, as component C) 0% to 10% of at least one further inorganic flame retardant which is zinc borate, zinc stannate, zinc phosphate, zinc pyrophosphate, magnesium borate and/or calcium stannate, as component D) 0% to 20% by weight of one or more condensation products of melamine, as component E) 0% to 2% by weight of at least one phosphite or phosphinite or mixtures thereof and as component F) 0% to 2% by weight of at least one ester and/or salt of long chain aliphatic carboxylic acids (fatty acids) typically having chain lengths of C.sub.14 to C.sub.40, where the sum total of the components is always 100% by weight.

2. The flame retardant mixture as claimed in claim 1, comprising 35% to 55% by weight of component A), 45% to 65% by weight of component B), 0% to 10% by weight of component C), 0% to 20% by weight of component D), 0% to 2% by weight of component E) and 0% to 2% by weight of component F).

3. The flame retardant mixture as claimed in claim 1, comprising 38% to 45% by weight of component A), 45% to 60% by weight of component B), 2% to 10% by weight of component C), 0% to 20% by weight of component D), 0% to 2% by weight of component E) and 0% to 2% by weight of component F).

4. The flame retardant mixture as claimed in claim 1, comprising 37% to 45% by weight of component A), 53% to 60% by weight of component B), 2% to 7% by weight of component C), 0% to 20% by weight of component D), 1% to 2% by weight of component E) and 0% to 2% by weight of component F).

5. The flame retardant mixture as claimed in claim 1, comprising 30% to 54.7% by weight of component A), 45% to 70% by weight of component B), 0.1% to 10% by weight of component C), 0% to 20% by weight of component D), 0.1% to 2% by weight of component E) and 0.1% to 2% by weight of component F).

6. The flame retardant mixture as claimed in claim 1, comprising 30% to 54.6% by weight of component A), 45% to 70% by weight of component B), 0.1% to 10% by weight of component C), 0.1% to 20% by weight of component D), 0.1% to 2% by weight of component E) and 0.1% to 2% by weight of component F).

7. The flame retardant mixture as claimed in claim 1, wherein R.sup.1 and R.sup.2 in component A) are the same or different and are methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl and/or phenyl.

8. The flame retardant mixture as claimed in claim 1, wherein component D) is melam, melem and/or melon.

9. The flame retardant mixture as claimed in claim 1, wherein component D) is melem.

10. The flame retardant mixture as claimed claim 1, which further comprises telomers as component G) and wherein the telomers are ethylbutylphosphinic acid, dibutylphosphinic acid, ethylhexylphosphinic acid, butylhexylphosphinic acid, ethyloctylphosphinic acid, sec-butylethylphosphinic acid, 1-ethylbutyl butyl phosphinic acid, ethyl-1-methylpentylphosphinic acid, di-sec-butylphosphinic acid (di-1-methylpropylphosphinic acid), propylhexylphosphinic acid, dihexylphosphinic acid, hexylnonylphosphinic acid, dinonylphosphinic acid and/or zinc salts thereof; wherein components A) and G) are different.

11. A polymer composition comprising a flame retardant mixture as claimed in claim 1 and as component H) thermoplastic and/or thermoset polymers.

12. The polymer composition as claimed in claim 11, wherein the thermoplastic polymer comprises polyam ides and/or polyesters.

13. The polymer composition as claimed in claim 12, 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.

14. The polymer composition as claimed in claim 12, wherein polyamide is nylon-6,6 or copolymers or polymer blends of nylon-6,6 and nylon-6.

15. The polymer composition as claimed in claim 12, wherein the polyesters are polybutylene terephthalate (PBT) or polyethylene terephthalate (PET) or blends of PBT and PET or polyester elastomers.

16. The polymer composition as claimed in claim 11, which comprises: 1% to 96% by weight of polymer; 0% to 50% by weight of filler and/or reinforcer; and 3% to 35% by weight of the flame retardant mixture, where the percentages are based on the total amount of the polymer composition.

17. The polymer composition as claimed in claim 16, which comprises: 15% to 75% by weight of polymer; 15% to 45% by weight of filler and/or reinforcer; and 10% to 25% by weight of the flame retardant mixture, where the percentages are based on the total amount of the polymer composition.

18. The polymer composition as claimed in claim 17, which comprises: 35% to 65% by weight of polymer; 25% to 35% by weight of filler and/or reinforcer; and 15% to 25% by weight of the flame retardant mixture, where the percentages are based on the total amount of the polymer composition.

19. The polymer composition as claimed in claim 11, which has a comparative tracking index, measured by International Electrotechnical Commission Standard IEC-60112/3, of not less than 500 volts.

20. The polymer composition as claimed in claim 11, which attains a V-0 assessment according to UL-94, especially measured on moldings of thickness 3.2 mm to 0.4 mm.

21. The polymer composition as claimed in claim 11, which has a glow wire flammability index to IEC 60695-2-12 of not less than 960° C., especially measured on moldings of thickness 0.75-3 mm.

22. The polymer composition as claimed in claim 11, which has a glow wire ignition temperature (GWIT) according to IEC-60695-2-13 of at least 775° C.

23. The polymer composition as claimed in claim 11, which comprises further additives as component H which are antioxidants, UV stabilizers, gamma-ray stabilizers, hydrolysis stabilizers, co-stabilizers for antioxidants, antistats, emulsifiers, nucleating agents, plasticizers, processing auxiliaries, impact modifiers, dyes, pigments, fillers, reinforcers and/or further flame retardants.

24. The polymer composition as claimed in claim 11, which comprises glass fibers.

25. The use of the polymer composition as claimed in claim 11 as molding compounds, semifinished products or finished products in the electrical, electronics and motor vehicle industries, in packaging in the food sector or in the games and toys sector, as label motifs, in medical technology or as plastic tags for individual labeling of animals.

26. The use of the polymer composition as claimed in claim 11 for production of parts of printed circuit boards, housings, foils, wires, switches, distributors, relays, resistors, capacitors, coils, lamps, diodes, LEDs, transistors, connectors, controllers, storage devices and sensors, in the form of large-area components, especially of housing parts for switchgear and in the form of components of complex shape with demanding geometry.

Description

EXAMPLES

[0151] 1. Components Used

[0152] Commercial polyamides:

[0153] Nylon-6,6 (PA 6,6-GR): Ultramid® A27 (from BASF SE, Germany)

[0154] Nylon-6: Ultramie® B27 (from BASF SE, Germany)

[0155] Nylon-6T/6,6: Vestamid® HTplus M1000 (from Evonik, Germany)

[0156] Nylon-10T: Vestamid® HTplus M3000 (from Evonik, Germany)

[0157] PPG HP 3610 glass fibers with diameter 10 μm and length 4.5 mm (from PPG, the Netherlands)

[0158] Flame retardant (component A)):

[0159] zinc salt of diethylphosphinic acid, referred to hereinafter as DEPZN

[0160] By way of comparison:

[0161] aluminum salt of diethylphosphinic acid, referred to hereinafter as DEPAL

[0162] Flame retardant (component B)):

[0163] B1: melamine polyphosphate, Melapur® 200/70, from BASF AG, D, referred to as MPP

[0164] B2: zinc melamine phosphate, Safire® 400, from Huber, USA

[0165] Flame retardant (component C)):

[0166] C1: Firebrake® 500 zinc borate, from Rio Tinto, USA

[0167] C2: zinc stannate, Flamtare® S, from William Blythe, UK

[0168] Flame retardant (component D)):

[0169] Delflam® NFR (melem)

[0170] Phosphonites (component E)): Sandostab® P-EPQ, from Clariant GmbH, Germany

[0171] Wax components (component F)):

[0172] Licowae® E, from Clariant Produkte (Deutschland) GmbH, Germany (esters of montan wax acid)

[0173] 2. Production, Processing and Testing of Flame-Retardant Polyamide Molding Compounds

[0174] 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.

[0175] 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).

[0176] The UL 94 fire classifications are as follows: [0177] 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. [0178] 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. [0179] V-2: cotton indicator ignited by flaming drops, other criteria as for V-1.

[0180] not classifiable (ncl): does not comply with fire classification V-2.

[0181] 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.

[0182] 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.

[0183] Corrosion was studied with the aid of the plaque method.

[0184] The plaque method, developed at the DKI (German Plastics Institute, Darmstadt), provides for model studies for comparative assessment of metallic materials or the corrosion and wear intensity of plastifying molding compounds. In this test, two specimens are arranged in pairs in the nozzle such that they form a rectangular gap of length 12 mm, width 10 mm and height adjustable from 0.1 to a maximum of 1 mm for the passage of the plastic melt (FIG. 1). Plastic melt is extruded (or injection-molded) through this gap from a plastifying unit with occurrence of high local shear stresses and shear rates in the gap.

[0185] A wear measurement parameter is the loss of weight of the test specimens determined by difference weighing of the test specimens with an analytical A&D Electronic Balance with a difference of 0.1 mg. The mass of the test specimens was determined before and after the corrosion test, in each case with polymer throughput 25 or 50 kg.

[0186] After a predefined throughput (generally 25 or 50 kg), the sample plaques are deinstalled and adhering plastic is cleaned off by physical/chemical means. Physical cleaning is effected by removal of the hot plastic mass by rubbing with a soft material (cotton). Chemical cleaning is effected by heating the test specimens to 60° C. in m-cresol for 20 minutes. Plastic mass still adhering after the boiling is removed by rubbing with a soft cotton pad.

[0187] All tests in the respective series, unless stated otherwise, were performed under identical conditions (temperature programs, screw geometry, injection molding parameters, etc.) for comparability.

[0188] The results in which the flame retardant-stabilizer mixture according to the invention was used are listed in examples I1-I3. 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 PA 66 GF 30 test results. C1-C4 are comparative examples, I1 to I3 inventive flame retardant mixtures in the polyamide molding compound C1 C2 C3 C4 I1 I2 I3 Nylon-6,6 [% by wt.] 49.55 49.55 49.55 49.55 49.55 49.55 47.55 HP3610 glass fibers [% by wt.] 30 30 30 30 30 30 30 A: DEPZN [% by wt.] 13 8 9 10 DEPAL [% by wt.] 13 8 9 B1: MPP [% by wt.] 6 11 9 6 11 9 11 C1: zinc borate [% by wt.] 1 1 2 1 1 2 1 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-0 V-0 V-0 V-1 V-0 V-0 V-0 GWFI at thickness 0.4 mm [° C.] 960 960 960 960 960 960 960 MVR 275° C./2.16 kg 4 5 5 15 10 12 12 GWIT at thickness 0.75 mm [° C.] 725 800 775 700 800 750 800 Corrosion [weight loss**] [%] 0.4 1 0.4 0.1 0.1 <0.1 0.2 Exudation* moderate high moderate moderate moderate moderate moderate CTI [volts] 600 550 600 600 600 600 600 Impact resistance [kJ/m.sup.2] 60 63 58 69 68 71 70 Notched impact resistance [kJ/m.sup.2] 10 10 11 15 14 14 13 *14 days 100% humidity 70° C. **of the metal plaques, weight before test 6 g

[0189] Only the inventive combination of zinc phosphinate, melamine polyphosphates and zinc borate gives polyamide molding compounds that attain the UL 94 V-0 fire class at 0.4 mm and at the same time have a GWIT greater than 775° C. and CTI 600 volts, low corrosion, modern exudation and impact resistance greater than 65 kJ/m.sup.2, a notched impact resistance greater than 10 kJ/m.sup.2.

[0190] By contrast, the combination of aluminum phosphinate with melamine polyphosphate and zinc borate shows distinct corrosion and significant exudation, and lower impact and notched impact resistance.

[0191] Furthermore, the polyamides with the combination of the invention do not show any mold deposits in injection molding, whereas mold deposits take place with the comparative examples even after 200 shots, which necessitates cleaning of the mold.

TABLE-US-00002 TABLE 2 PA 66 GF 30 test results. I4 to I10 inventive flame retardant mixtures in the polyamide molding compound I4 I5 I6 I7 I8 I9 I10 Nylon-6,6 [% by wt.] 49.55 49.55 49.55 49.55 39.55 39.55 49.55 Nylon-6T/66 [% by wt.] 10 Nylon-6 [% by wt.] 10 HP3610 glass fibers [% by wt.] 30 30 30 30 30 30 30 A: DEPZN [% by wt.] 8 8 8 8 8 8 9.5 B1: MPP [% by wt.] 11 8 6 11 11 9.5 B2: Satire 400 [% by wt.] 11 D: melem [% by wt.] 3 5 C1: zinc borate [% by wt.] 1 1 1 1 1 C2: zinc stannate [% by wt.] 1 1 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-1 V-0 V-0 V-0 GWFI at thickness 0.4 mm [° C.] 960 960 960 960 960 960 960 MVR 275° C./2.16 kg 14 13 15 12 10 17 12 GWIT at thickness 0.75 mm [° C.] 775 800 775 775 825 825 800 Corrosion [%] 0.3 <0.1 0.1 <0.1 0.1 0.1 0.1 Exudation* moderate low moderate low low moderate moderate CTI [volts] 600 550 600 600 600 600 600 Impact resistance [kJ/m.sup.2] 63 68 67 69 68 69 70 Notched impact resistance [kJ/m.sup.2] 10 12 13 15 12 14 12 *14 days 100% humidity 70° C.

[0192] Overall, only the combinations of the invention attain all the parameters to be fulfilled.

TABLE-US-00003 TABLE 3 PA 6 GF 30 test results. C5-C7 are comparative examples, I11 to I14 inventive flame retardant mixtures in the polyamide molding compound C5 C6 C7 I11 I12 I13 I14 Nylon-6 [% by wt.] 49.55 49.55 49.55 48.55 49.55 49.55 45.55 HP3610 glass fibers [% by wt.] 30 30 30 30 30 30 30 A: DEPZN [% by wt.] 13 10 8 9 11.5 DEPAL [% by wt.] 13 8 B1: MPP [% by wt.] 6 11 6 10 11 9 11.5 C1: zinc borate [% by wt.] 1 1 1 1 1 2 1 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-0 V-1 V-1 V-0 V-1 V-0 V-0 GWFI at thickness 0.4 mm [° C.] 960 960 960 960 960 960 960 MVR 250° C./2.16 kg 5 5 13 12 10 11 13 GWIT at thickness 0.75 mm [° C.] 700 800 775 800 825 775 825 Corrosion [weight loss**] [%] 0.3 0.8 0.4 0.1 0.1 <0.1 0.1 Exudation* moderate high moderate moderate moderate moderate moderate CTI [volts] 600 550 600 600 600 600 600 Impact resistance [kJ/m.sup.2] 62 64 59 69 68 71 70 Notched impact resistance [kJ/m.sup.2] 11 11 12 15 14 15 14 *14 days 100% humidity 70° C. **of the metal plaques, weight before test 6 g

[0193] In nylon-6 with glass fibers too, only the combinations of the invention attain all the parameters to be fulfilled. No mold deposits are observed here either in injection molding for the formulations of the invention.