FLAME-RETARDANT MOLDING COMPOUNDS CONTAINING SILOXANE-CONTAINING POLYCARBONATE BLOCK CO-CONDENSATE

Abstract

The present invention relates to flame-retardant moulding compositions comprising siloxane-containing polycarbonate block cocondensate, and also to a process for the production of these moulding compositions. The invention further relates to the use of these flame-retardant moulding compositions in injection-moulding and extrusion applications.

Claims

1.-13. (canceled)

14. A flame-retardant, thermoplastic moulding compositions comprising (A) at least one polysiloxane-polycarbonate block cocondensate comprising siloxane blocks of the structure (1) ##STR00008## where R.sup.1 is H, Cl, Br or C.sub.1 to C.sub.4-alkyl, R.sup.2 and R.sup.3 are selected mutually independently from aryl, C.sub.1 to C.sub.10-alkyl and C.sub.1 to C.sub.10-alkylaryl, X is a single bond, —CO—, —O—, C.sub.1- to C.sub.6-alkylene, C.sub.2 to C.sub.5-alkylidene, C.sub.5 to C.sub.12-cycloalkylidene or C.sub.6 to C.sub.12-arylene, which can have been condensed with another aromatic ring comprising heteroatoms, n is an average value from 1 to 500, m is an average value from 1 to 10 and p is 0 or 1; (B) from 0.03 to 0.25% by weight of polytetrafluoroethylene or from 0.05 to 0.30% by weight of polytetrafluoroethylene blends which comprise from 30 to 70% by weight of polytetrafluoroethylene, and (C) from 0.1 to 0.6% by weight of at least one sulphonic salt, wherein the moulding compositions have a chlorine content of from 10 to 1000 ppm.

15. The moulding composition according to claim 14, wherein one or more chlorine-containing colorants are present.

16. The moulding composition according to claim 15, wherein the moulding compositions comprise at least one chlorine-containing colorant from the class of the chlorinated aromatics and/or titanium oxide prepared by the chloride process.

17. The moulding composition according to claim 14, wherein the moulding compositions comprise at least one chlorine aromatic selected from the classes of the phthalocyanine dyes and perinone dyes.

18. The moulding composition according to claim 14, wherein polytetrafluoroethylene with average particle diameter from 100 to 1000 μm is present as component (B).

19. The moulding composition according to claim 14, wherein at least one polytetrafluoroethylene blend is present as component (B) in the moulding compositions, where the polytetrafluoroethylene blend comprises a polytetrafluoroethylene core and a coating made of at least one polyvinyl derivative.

20. The moulding composition according to claim 14, wherein at least one sulphonic salt of the general formulae (4) and (5) is present as component (C) ##STR00009## where R.sub.4, R.sub.5, R.sub.6 and R.sub.7 are respectively mutually independently a C.sub.1 to C.sub.6-alkyl moiety, Me and M are respectively a metal, a and n are 1, 2 or 3, b and w are integers from 0 to 5, and x and y are integers from 0 to 4.

21. The moulding composition according to claim 14 composed of components (A), (B), (C) and (D) from 0.00% by weight to 20.00% by weight of one or more UV absorbers; (E) from 0.00% by weight to 1.00% by weight of one or more mould-release agents; (F) from 0.00% by weight to 0.20% by weight of one or more heat stabilizers and/or processing stabilizers; (G) from 0.00 to 10.00% by weight of other additives which differ from components (B) to (F); and (H) from 0.00% to 40.00% by weight of one or more (co)polycarbonates which do not have any siloxane units.

22. The moulding composition according to claim 14, wherein the quantity present of component A in the moulding compositions is at least 50% by weight.

23. The moulding composition according to claim 14, wherein the polysiloxane-polycarbonate block cocondensate comprises polycarbonate blocks based on bisphenol A.

24. The moulding composition according to claim 14, wherein the polysiloxane-polycarbonate block cocondensate comprises one or more structures of the formulae (I), (II), (III) and (IV): ##STR00010## where the phenyl rings are unsubstituted or mutually independently mono- or disubstituted with C.sub.1 to C.sub.8-alkyl and/or halogen, X is a single bond, C.sub.1 to C.sub.6-alkylene, C.sub.2 to C.sub.5-alkylidene or C.sub.5 to C.sub.6-cycloalkylidene, and the linkages indicated by -- in the structural units (I) to (IV) are respectively part of a carboxy group.

25. The moulding composition according to claim 14, wherein the content of siloxane blocks of the structure (1) is from 2 to 20% by weight, based on the total weight of the moulding compositions.

26. The moulding composition according to claim 14, wherein the energy absorbed in the Izod notched impact test at −30° C. on injection mouldings produced therefrom is at least 30 kJ/m.sup.2, measured in accordance with ISO 180/1A on test specimens measuring 80×10×3 mm or 80×10×4 mm, and the UL 94 classification of said injection mouldings, for thickness 1.5 mm, is V-0.

Description

EXAMPLES

[0167] Materials for the production of the compositions and of corresponding test samples:

Component (A)

[0168] Polysiloxane-polycarbonate block cocondensate (also termed Si—PC below) comprising bisphenol A homopolycarbonate blocks and siloxane blocks of the general formula (1) where R.sup.1═H, R.sup.2, R.sup.3=methyl, p=0, n is in the range from 30 to 35 and m is in the range from 3.5 to 4.0. The relative solution viscosity of the block cocondensate is 1.30 (determined at a concentration of 5 g/l in dichloromethane at 25° C. with an Ubbelohde viscometer).

[0169] The block cocondensate was produced by a melt transesterification process from a bisphenol A homopolycarbonate and a siloxane. The following components were used here:

[0170] Polycarbonate component: Linear bisphenol-A homopolycarbonate having terminal groups based on phenol with melt volume rate MVR about 59 cm.sup.3/10 min (measured at 300° C. with 1.2 kg loading in accordance with ISO 1033), produced by a melt transesterification process as described in DE 102008019503. This component comprises transposition structures of the formulae (I), (II), (III) and (IV). The content of transposition structures can be determined by determining the quantities of the corresponding degradation products (Ia) to (IVa) after use of sodium methanolate for complete suponification at reflux. The degradation products found by means of HPLC with UV detection were the following: (Ia): 142 ppm; (IIa): <10 ppm, (IIIa): <10 ppm, (IVa): 23 ppm.

[0171] Siloxane component: Hydroquinone-terminated polydimethylsiloxane of the formula (I) (i.e. R.sup.1═H, R.sup.2=methyl, p=0), where n is in the range from 30 to 35 and m is in the range from 3.5 to 4.0; produced as described in US 2013/0267665 A1, Example 1.

[0172] The block cocondensate made of the polycarbonate component and of the siloxane component is produced by way of a reactive extrusion process:

[0173] A diagram of the experimental set-up can be found in FIG. 1.

[0174] FIG. 1 is a diagram of the production of the siloxane-containing block cocondensates. Polycarbonate and a catalyst masterbatch (see below) are metered by way of the gravimetric feeds (4) and (5) into the twin-screw extruder (1). The extruder (ZSE 27 MAXX from Leistritz Extrusionstechnik GmbH, Nuremberg) is a corotating twin-screw extruder with vacuum zones for removal of the vapours. The extruder is composed of 11 barrel sections (a to k)—see FIG. 1. In barrel section a polycarbonate and catalyst masterbatch are added, and in barrel section b and c these components are melted. In barrel section d the liquid silicone component is added. Barrel sections e and f serve to mix the liquid silicone component into the material. Barrel sections g, h, i and j have vents for removing the condensation products. Barrel sections g and h are part of the first vacuum stage, and barrel sections i and j are part of the second vacuum stage. The vacuum in the first vacuum stage comprised an absolute pressure of from 250 to 500 mbar. The vacuum in the second vacuum stage comprised a pressure of less than 1 mbar. The siloxane is provided in a tank (6) and added to the extruder by way of a metering pump (7). The vacuum is generated by way of 2 vacuum pumps (8). The vapours are removed from the extruder and collected (9) in 2 condensers. The resultant devolatilized melt is conducted by way of a line from barrel section k of the twin-screw extruder to a high-viscosity reactor (2).

[0175] The high-viscosity reactor (2) is a self-cleaning apparatus with two contra-rotating, horizontal rotors arranged with parallel axes. The structure is described in FIG. 7 of the European Patent Application EP0460466. The rotor diameter of the machine used is 187 mm, with length 924 mm. The volume of the entire space within the reactor is 44.6 litres. Attached to the high-viscosity reactor there is likewise a vacuum pump (8) and a condenser (9). The vacuum applied to the high-viscosity reactor comprises a pressure of from 0.1 to 5 mbar. After conclusion of the reaction the block cocondensate is discharged by way of a discharge screw and then pelletized (by way of water bath (10) and pelletizer (11)). The molecular weight of the block cocondensate is controlled by way of the throughput. The throughput in the extruder/high-viscosity reactor combination is adjusted in such a way to give a solution viscosity of eta rel 1.30 for the block cocondensate (determined at a concentration of 5 g/l in dichloromethane at 25° C. with an Ubbelohde viscometer).

[0176] The catalyst masterbatch required for the production of the block cocondensate is produced as follows: The catalyst is tetraphenylphosphonium phenoxide from Rhein Chemie Rheinau GmbH (Mannheim, Germany). The catalyst is used in the form of a masterbatch. Tetraphenylphosphonium phenoxide is used in the form of Co-crystal with phenol and comprises about 70% of tetraphenylphosphonium phenoxide. The content values specified below relate to the product from Rhein Chemie (i.e. in the form of the co-crystal with phenol).

[0177] The masterbatch used takes the form of a 0.25% dilution. This is produced by mixing 4982 g of polycarbonate with 18 g of tetraphenylphosphonium phenoxide (in the form described above) in a gym-wheel mixer for 30 minutes. The metering ratio for the masterbatch is 1:10, and the catalyst content is therefore 0.025% by weight, based on the polycarbonate used.

Component (B)

[0178] PTFE powder CFP 6000 from DuPont with average particle diameter about 490 μm and bulk density about 460 g/L. Blendex B449 (about 50% of PTFE and about 50% of SAN [made of 80% of styrene and 20% of acrylonitrile] from Chemtura.

Component (C)

[0179] Potassium diphenyl sulphone sulphonate: product name KSS-FR from Brenntag GmbH, Germany.

Component (D)

[0180] Tinuvin® 234 (bis(1,1-dimethylbenzyl)-2′-hydroxyphenyl)benzotriazole, BASF SE, Ludwigshafen) is used as UV absorber.

Component (F)

[0181] Irgafos® 168 (tris(2,4-di-tert-butylphenyl)phosphite, CAS 31570-04-4, BASF SE, Ludwigshafen) is used as heat stabilizer.

Component (G)

[0182] Colorant

[0183] Carbon black (particle size about 17 nm) in the form of Black Pearls® 800 (CAS No. 1333-86-4) from Cabot Corp. is used as colorant.

[0184] Macrolex Red EG (Solvent Red 135, CAS No. 20749-68-2) from Lanxess AG, Leverkusen, is used as colorant.

[0185] Potassium perfluoro-1-butanesulphonate, obtainable commercially as Bayowet® C4 from Lanxess, Leverkusen, Germany, CAS No. 29420-49-3 is used as flame retardant which is not in accordance with the invention.

Component (H)

[0186] Linear bisphenol A homopolycarbonate having terminal groups based on phenol with melt volume rate MVR 6 cm.sup.3/10 min (measured at 300° C. with 1.2 kg loading in accordance with ISO 1033), also referred to below as PC 1.

[0187] The additives were compounded in a Berstorff ZE25 twin-screw extruder from KrausMaffei at a barrel temperature of 260° C. and a melt temperature of 280° C. at rotation rate 150 rpm, the quantities of additives being those shown in the Examples.

[0188] The pellets were dried in vacuo for 3 hours at 120° C. and then processed in an Arburg 370 with a 25 injection unit injection-moulding machine at a melt temperature of 300° C. and a mould temperature of 80° C. to give appropriate mouldings. The starting materials used here are those stated in Table 1, at the stated concentrations.

[0189] Examples 1 and 2 are inventive examples; Examples 3 to 6 are comparative examples.

[0190] Melt volume rate (MVR) is determined in accordance with ISO 1133 (at 300° C.; 1.2 kg).

[0191] Fire performance is measured in accordance with UL 94V on specimens measuring 127 mm×12.7 mm×3.0 mm and on specimens measuring 127×12.7×1.5 mm.

[0192] Two sets of in each case 5 UL test samples of the thickness stated above were then tested by a method based on UL 94V. One set was tested after 48 hours of storage at 50% rel. humidity and 23° C. Another set was tested after 7 days of storage at 70° C. in an oven. (The total number of UL test samples tested in each case was 10.)

[0193] Mechanical properties are determined on, in each case, 10 test specimens measuring 80×10×4 and 80×10×3 mm (see Table 2 for thickness of the test specimens) (Izod notched impact measured in accordance with ISO 180/1A; 23° C. and −30° C.).

[0194] Inventive Examples 1 and 2 and Comparative Examples 3 to 6 are produced with the additives and raw materials stated in Table 1 at the respective concentrations stated (in % by weight) under the conditions stated above.

TABLE-US-00001 TABLE 1 Example 3 Example 4 Example 5 Example 6 Component Example 1 Example 2 (Comparison) (Comparison) (Comparison) (Comparison) (A) Si—PC 95    95    95    95    95    95    (H) PC 1 3.78 3.85 3.43 4.08 3.83 3.83 (B) Blendex 0.15 — 0.60 0.15 0.40 — (B) PTFE powder — 0.08 — — — 0.3  (C) 0.40 0.40 0.30 0.40 0.40 0.30 (D) 0.27 0.27 0.27 0.27 0.27 0.27 (F) 0.10 0.10 0.10 0.10 0.10 0.10 G) Carbon black 0.20 0.20 0.20 — 0.20 0.20 G) Macrolex Red EG 0.10 0.10 0.10 — 0.10 — G) Potassium — — — — 0.10 — perfluoro-1- butanesulphonate

TABLE-US-00002 TABLE 2 Ex.3 Ex. 4 Ex. 5 Ex. 6 Ex. 1 Ex. 2 (Comparison) (Comparison) (Comparison) (Comparison) Chlorine content 250 260 220 2 170 4 (ppm) Izod notched 23° C. 64 d * 63 d * — 64 d * 68 d — [kJ/m.sup.2] Izod notched −30° C. 40 d * 43 d * 25 b 46 d −40° C. * 4 Test 28 b [kJ/m.sup.2] specimens: 32 d 6 Test specimens: 26 b UL 3.0 mm V0 V0 V0 V0 V0 V0 UL 1.5 mm V0 V0 V1 V1 V1 V0 *thickness of the test specimen in Izod notched impact test = 4 mm; b: brittle fracture in the Izod notched impact test; d: toughness behaviour in the Izod notched impact test; for examples 3, 5 and 6, the thickness of the test specimen in the Izod notched impact test = 3 mm.

[0195] It is seen that the examples according to the invention exhibit the combination of good fire performance and excellent low-temperature notched impact toughness, whereas the comparative examples, which have excessively low content of chlorine (Examples 4 and 6) or excessively high content of component B (Examples 3 and 5), exhibit weaknesses in fire behaviour and/or in the mechanical properties.