FLAME-RETARDANT POLYAMIDE MOLDING COMPOUNDS

Abstract

The disclosed thermoplastic molding material includes a specific combination of at least three flame retardant additives in addition to at least one thermoplastic polyamide and glass fibers. In some embodiments, the present invention has for its object the provision of specific mixtures of flame retardant input materials which result in glass fiber reinforced polyamide molding materials which pass not only the UL 94 requirements but also the glow wire test in its various forms and can also be processed without discoloration.

Claims

1. A thermoplastic molding material comprising a) 25.0 to 64.5 wt % of at least one thermoplastic polyamide as component A, b) 2.0 to 8.0 wt % of at least one phosphazene of general formula (IX) or (X) ##STR00027## in which m is an integer from 3 to 25 and R.sup.4 and R.sup.4 are identical or different and represent C.sub.1-C.sub.20-alkyl-, C.sub.6-C.sub.30-aryl-, C.sub.6-C.sub.30-arylalkyl- or C.sub.6-C.sub.30-alkyl-substituted aryl or linear phosphazenes of general formula (X), n represents 3 to 1000 and X represents NP(OPh).sub.3 or NP(O)OPh and Y represents P(OPh).sub.4 or P(O)(OPh).sub.2, as component B, c) 1.5 to 6.0 wt % of at least one aliphatic or aromatic ester of phosphoric acid or polyphosphoric acid as component C, d) 5.0 to 30.0 wt % of at least one metal phosphinate or phosphinic acid salt of general formula (I) or diphosphinic acid salt of general formula (II) or polymers thereof ##STR00028## in which R.sup.1, R.sup.2 are identical or different and represent hydrogen, C.sub.1-C.sub.6-alkyl, linear or branched, and/or aryl; R.sup.3 represents C.sub.1-C.sub.10-alkylene, linear or branched, C.sub.6-C.sub.10-arylene, -alkylarylene or -arylalkylene; 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=1 to 4; n=1 to 4; x=1 to 4, preferably m=3, x=3, as component D, e) 26.0 to 65.0 wt % of glass fibers as component E, f) 0 to 10.0 wt % of further assistants as component F, wherein the total of components A to E sums to 100.0 wt %.

2. The thermoplastic molding material according to claim 1, wherein a cyclic phenoxyphosphazene having at least 3 phenoxyphosphazene units is employed as component B.

3. The thermoplastic molding material according to claim 1, wherein component C is selected from aromatic polyphosphates.

4. The thermoplastic molding materials according to claim 1, wherein in component D R.sup.1, R.sup.2 are identical or different and represent hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert.-butyl, n-pentyl and/or phenyl and R.sup.3 represents methylene, ethylene, n-propylene, isopropylene, n-butylene, tert-butylene, n-pentylene, n-octylene or n-dodecylene, phenylene or naphthylene; methylphenylene, ethylenephenylene, tert-butylphenylene, methylnaphthylene, ethylnaphthylene or tert-butylnaphthylene; phenylmethylene, phenylethylene, phenylpropylene or phenylbutylene.

5. The thermoplastic molding material according to according to claim 1, wherein component A is a blend of at least one aliphatic polyamide and at least one semiaromatic or aromatic polyamide.

6. The thermoplastic molding material according to claim 1, wherein component B is employed in an amount of 2.0 to 6.0 wt %, preferably 3.0 to 5.0 wt %, based on the total of components A to E which sums to 100%.

7. The thermoplastic molding material according to according to claim 1, wherein 2.5 to 5.5 wt %, preferably 3.0 to 5.0 wt %, of at least one aliphatic or aromatic ester of phosphoric acid or polyphosphoric acid are employed as component C.

8. A process for producing thermoplastic molding materials according to according to claim 1 by mixing the ingredients.

9. (canceled)

10. A molded article, fiber or film made of a thermoplastic molding material according to according to claim 1.

11. A process for producing molded articles, fibers or films made of a thermoplastic molding material according to claim 1 by melting, extruding and subsequent molding of a thermoplastic molding material according to claim 1.

12. (canceled)

13. (canceled)

Description

EXAMPLES

[0209] Input materials:

TABLE-US-00006 A PA66 VZ 120 cm.sup.3/g, UltramidA24, BASF SE polyamide 6 VZ 150 cm.sup.3/g, UltramidB27, BASF SE PA6I/6T Selar A 3426, DuPont B cyclophosphazene Rabitle FP 110, Fushimi Co. C aromatic polyphosphate PX-200, Daihachi Chemical D aluminum diethylphosphinate salt e.g. Exolit OP 1230, (DEPAL) Clariant AG E glass fiber OCF DS 1110 F melamine poly(aluminumphosphate) Satire 400 melamine polyphosphate (MPP) Melapur M200, BASF Schweiz (only in comparative examples)

[0210] Processing:

[0211] The individual components were mixed in a twin-screw extruder (ZSK 25) at a throughput of about 20 kg/h and about 280 C. (PA66) at a flat temperature profile, extruded, cooled until pelletizable and pelletized. The test specimens for the investigations set out in the tables were injection molded on an Arburg 420 injection molding machine at a melt temperature of about 260 to 280 C. and a mold temperature of about 80 C.

[0212] The compositions of the molding materials and the results of the measurements may be found in the tables.

[0213] Testing:

[0214] The mechanical properties were determined according to ISO 527-2/1A/5 and Charpy impact strength (unnotched) was determined according to ISO 179-2/1eU.

[0215] The flame retardancy of the molding materials was firstly determined according to method UL94-V (Underwriters Laboratories Inc. Standard of Safety, Test for Flammability of Plastic Materials for Parts in Devices and Appliances, Northbrook 1998, page 14 to page 18).

[0216] Glow wire test:

[0217] Glow wire tests were performed according to DIN EN 60695-2-11/-12/-13 (edition valid in March 2017). As a criterion for the test on the component part, a plug in this case, reported in the examples it was observed in accordance with IEC 60335-1 whether flame formation is visible for a period of >2 s. The temperature reported in the examples is the maximum glow wire temperature at which no flame formation occurred.

[0218] A plug which may be regarded as typical for the relevant product class was used as the component part in the examples by way of example. The plug comprises sections of different wall thickness (0.8 mm in thin places, 2 mm in thick places and has external dimensions of 23 mm10 mm17 mm). The plugs were produced with molding materials according to the invention and exhibit no dark spots.

[0219] TGA:

[0220] Thermogravimetric analysis was performed with a TA Instruments Q5000IR instrument. The sample mass was 2 mg to 3 mg. Samples were weighed in aluminum crucibles and the material was heated from 40 C. to 600 C. at a constant heating rate of 20 C. min.sup.1 under nitrogen flow.

Examples I

[0221]

TABLE-US-00007 1 2 3 C1 C2 C3 C4 C5 C6 C7 C8 Ultramid A24 44 39 32 33.5 45 37 35 36 43 35.6 45 Selar PA 3426 8 13 7 7.0 0 7 15 7 8 7.1 8 Ultramid B22 0 0 5 4.5 0 5.0 0 5 0 4.7 0 Glass fiber DS 30 30 30 30 30 30 25 30 30 30 30 1110 Melapur 200 0 0 0 3 3 0 16.7 0 3 3 0 Safire 400 0 0 0 0 0 3 0 0 0 0 0 Rabitle FP-110 3 3 5 6 6 5 8.3 6 0 3.6 0 Exolit OP 1230 12 12 13 16 16 13 0 16 16 16 12 PX-200 3 3 5 0 0 0 0 0 0 0 5 Modulus of elastici- 9900 10050 9300 9950 9600 10500 9400 9900 8800 10300 10500 ty (MPa) Elongation at break 3.0 3.2 2.2 3.0 2.6 2.7 2.7 2.7 2.7 3.3 3.0 (%) Charpy aCU 75 75 32 66 51 37 53 64 66 72 78 (kJ/m.sup.2) GWT testing on 750 750 775 750 750 750 750 725 725 725 725 plug. Max. tem- perature ( C.) with- out ignition GWIT 2 mm sheet 800 875 UL V-94 0.8 mm V-0 V-0 V-0 V-0 V-0 V-0 C2 V-0 V-0 V-0 V-0 UL V-94 0.4 mm V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 C1 Visual appearance Light- Light- Light- Black Black Black Light- Light- Black Black Light- colored, colored, colored, marks marks spots colored, colored, marks marks colored, homoge- homoge- homoge- homoge- few marks homoge- neous neous neous neous neous no values available

[0222] As shown in the examples both the glow wire test on the sheet and on the component part and the UL 94 test at 0.4 mm wall thickness can be passed with a combination of phosphinates, cyclophosphazene and melamine polyphosphate (MPP) (comparative examples C1, C2). However the samples exhibit black planar colorations and also black spots. The dark colorations indicate an incompatibility of cyclophosphazene with melamine polyphosphates. Substitution of pure MPP with a modified melamine polyphosphate cannot achieve significant improvement (comparative example C3). Sheetlets (60 mm60 mm2 mm) produced by injection molding of an inventive molding material (1) and a noninventive molding material (C3) show by way of example a uniform light-colored surface for molding material (1) and gray streaks and a grayer coloration for molding material (C3). Molding materials comprising a large amount of MPP and cyclophosphazene can achieve very good resistance to the glow wire (comparative example C4) and the effect of MPP as a light-colored filler results in an attractive surface of the material. However a pass cannot be achieved in the vertical UL 94 test with such samples even at a wall thickness of 0.8 mm.

[0223] In turn, in formulations comprising cyclophosphazene without addition of MPP a pass cannot be achieved in the glow wire test at 750 C. (comparative example C5). Likewise, the addition of MPP without cyclophosphazene does not result in a pass in the glow wire test at 750 C. (comparative example C6). A reduced addition of the combination of MPP and cyclophosphazene likewise cannot result in a pass in the glow wire test at 750 C. (comparative example C7) and the dark coloration remains present.

[0224] In accordance with the invention all requirements of the glow wire and UL 94 test are achieved by combinations of cyclophosphazene, phosphinate and a phosphate ester (examples 1 to 3). The samples exhibit a homogeneous surface without colorations. If the phosphate ester is used without addition of the cyclophosphazene the molding materials exhibit too low a resistance to the glow wire and can achieve only a UL 94 V1 classification at a wall thickness of 0.4 mm (comparative example C8). The inventive molding materials 1 and 2 in particular exhibit not only good flame retardancy but also a very good impact strength.