FLAME-RETARDANT POLYCARBONATE COMPOSITION WITH LOW BISPHENOL A CONTENT

Abstract

The invention relates to a composition for production of a thermoplastic moulding compound, wherein the composition comprises or consists of at least the following constituents: A) 50.0% to 95.0% by weight of at least one polymer selected from the group consisting of aromatic polycarbonate, aromatic polyestercarbonate and aromatic polyester, B) 1.0% to 40.0% by weight of polymer free of epoxy groups, consisting of B1) rubber-modified graft polymer, prepared by emulsion polymerization and B2) optionally rubber-free vinyl (co)polymer, C) 0.1% to 7.5% by weight of a polymer containing structural elements that derive from styrene and an epoxy-containing vinyl monomer, D) 1.0% to 20.0% by weight of phosphorus-containing flame retardant, E) 0.1% to 10.0% by weight of additives, and F) 0% to 10.0% by weight of one or more fillers,
where component C) has a weight ratio of structural elements that derive from styrene to those that derive from epoxy-containing vinyl monomers of 100:1 to 1:1. The invention further relates to the use of the composition and to a process for producing such a moulding compound and to the moulding compound itself. The invention additionally relates to a moulded article formed from the aforementioned moulding compound.

Claims

1. A thermoplastic moulding composition, wherein the composition comprises: A) 50.0% to 95.0% by weight of at least one polymer selected from the group consisting of aromatic polycarbonate, aromatic polyestercarbonate and aromatic polyester, B) 1.0% to 40.0% by weight of polymer free of epoxy groups, consisting of B1) rubber-modified graft polymer prepared by emulsion polymerization and B2) optionally rubber-free vinyl (co)polymer, C) 0.1% to 7.5% by weight of a polymer comprising structural elements that derive from styrene and an epoxy-containing vinyl monomer; D) 1.0% to 20.0% by weight of phosphorus-containing flame retardant E) 0.1% to 10.0% by weight of additives; and F) 0% to 10.0% by weight of one or more fillers, wherein component C) has a weight ratio of structural elements that derive from styrene to those that derive from epoxy-containing vinyl monomers of 100:1 to 1:1.

2. The composition of claim 1, wherein component C) comprises structural units derived from at least one further vinyl monomer free of epoxy groups which is copolymerizable with styrene.

3. The composition of claim 1, wherein the weight ratio of the structural units derived from styrene to those derived from the vinyl monomers free of epoxy groups which are copolymerizable with styrene in component C) is in the range from 85:15 to 60:40.

4. The composition of claim 1, wherein component C) comprises structural units derived from acrylonitrile.

5. The composition of claim 1, wherein component C is a block polymer or graft polymer.

6. The composition of claim 1, wherein the vinyl monomer containing epoxy groups of component C) is selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, allyl glycidyl ether, vinyl glycidyl ether, vinylbenzyl glycidyl ether and propenyl glycidyl ether.

7. The composition of claim 1, wherein component B) comprises 40% to 90% by weight of component B1), based on component B).

8. The composition of claim 1, wherein component D) is at least one phosphorus-containing flame retardant of the general formula (IV) ##STR00010## in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are independently an in each case optionally halogenated C.sub.1 to C.sub.8-alkyl radical, or an in each case optionally alkyl-substituted C.sub.5 to C.sub.6-cycloalkyl, C.sub.6 to C.sub.20-aryl or C.sub.7 to C.sub.12-aralkyl radical, n is independently 0 or 1, q is an integer from 1 to 30, and X is a polycyclic aromatic radical which has 12 to 30 carbon atoms and is optionally substituted by halogen and/or alkyl groups ##STR00011##

9. The composition of claim 1, wherein component A has phenolic OH groups and the stoichiometric ratio of the epoxy groups of component C) to the phenolic OH groups of component A) is at least 1:1.

10. The composition of claim 1, wherein component E comprises 0.05% to 2.0% by weight of antidripping agents, and 0.05% to 2.0% by weight of demoulding agents and 0.05% to 2.0% by weight of stabilizers, based in each case on the sum of components A)-F).

11. The composition of claim 1, comprising: A) 51.0% to 85.0% by weight, of aromatic polycarbonate and/or aromatic polyestercarbonate; B) 2.0% to 25.0% by weight, of polymer free of epoxy groups, consisting of B1) rubber-modified graft polymer prepared by emulsion polymerization and B2) optionally rubber-free vinyl (co)polymer, C) 0.3% to 8.0% by weight, of the epoxy-vinyl polymer comprising or consisting of structural units that derive from styrene and from a vinyl monomer containing epoxy groups; D) 2.0% to 18.0% by weight, of phosphorus-containing flame retardant; E) 0.2% to 8.0% by weight, of additives; and F) 0.2% to 8.0% by weight of one or more fillers, where the amounts of components A) to F) are independent of one another.

12. The composition of claim 1, comprising: A) 55.0% to 85.0% by weight of aromatic polycarbonate and/or aromatic polyestercarbonate B) 4.0% to 20.0% by weight of polymer free of epoxy groups, consisting of B1) rubber-modified graft polymer prepared by emulsion polymerization and B2) optionally rubber-free vinyl (co)polymer; C) 3.0% to 6.0% by weight of the epoxy-vinyl polymer comprising or consisting of structural units that derive from styrene and from a vinyl monomer containing epoxy groups; D) 3.0% to 16.0% by weight of phosphorus-containing flame retardant; E) 0.5% to 6.0% by weight of additives; and F) 0% to 4.0% by weight of one or more fillers.

13-15. (canceled)

16. A moulded article comprising the composition of claim 1.

17. The composition of claim 1, wherein component C) has an epoxy content measured according to ASTM D 1652-11 in dichloromethane of 0.1% to 5% by weight.

18. The composition of claim 1, wherein component B) comprises 50% to 80% by weight of component B1), based on component B).

19. The composition of claim 1, wherein component D) has the following formula (V): ##STR00012##

20. The composition of claim 1, component A) has a proportion by weight of phenolic OH groups of 50 to 2000 ppm.

Description

EXAMPLES

[0248] Component A:

[0249] Linear polycarbonate based on bisphenol A having a weight-average molecular weight M.sub.W of 26 900 g/mol (determined by GPC in methylene chloride with polycarbonate based on bisphenol A as standard) and a proportion by weight of phenolic OH groups of 135 ppm.

[0250] Component B-1:

[0251] Graft polymer of 43 parts by weight of a copolymer of styrene and acrylonitrile in a ratio of 73:27 onto 57 parts by weight of a particulate crosslinked polybutadiene rubber (particle diameter of d.sub.50=350 nm), prepared by emulsion polymerization.

[0252] Component B-2:

[0253] SAN copolymer with 23% by weight acrylonitrile content and weight-average molecular weight about 130 000 g/mol (determined by GPC in tetrahydrofuran, using polystyrene as standard).

[0254] Component C:

[0255] Modiper™ CL430-G (NOF Corporation, Japan): polymer containing blocks of polycarbonate and blocks of glycidyl methacrylate-styrene-acrylonitrile terpolymer, which has been obtained by free-radical graft polymerization, initiated by a peroxide, of 30% by weight of a monomer mixture of styrene, acrylonitrile and glycidyl methacrylate in a ratio of 15:6:9% by weight in the presence of 70% by weight of linear polycarbonate based on bisphenol A. The epoxy content of component C measured according to ASTM D 1652-11 in dichloromethane is 2.4% by weight.

[0256] Component D:

[0257] Bisphenol-A-Based Oligophosphate

##STR00009##

[0258] Component E-1:

[0259] Cycolac INP 449: polytetrafluoroethylene (PTFE) preparation from Sabic composed of 50% by weight of PTFE, present in an SAN copolymer matrix.

[0260] Component E-2:

[0261] Pentaerythritol Tetrastearate

[0262] Component E-3:

[0263] Irganox B 900 (mixture of 80% Irgafos™ 168 (tris(2,4-di-tert-butylphenyl) phosphite) and 20% Irganox™ 1076 (2,6-di-tert-butyl-4-(octadecanoxycarbonylethyl)phenol); BASF (Ludwigshafen, Germany)

[0264] Component E-4:

[0265] Pural 200, aluminium oxide hydroxide, average particle size about 50 nm (manufacturer: Condea Hamburg)

[0266] Production and Testing of the Moulding Compounds According to the Invention

[0267] The components were mixed in a Werner & Pfleiderer ZSK-25 twin-screw extruder at a melt temperature of 260° C. The moulded articles were produced at a melt temperature of 260° C. and a mould temperature of 80° C. in an Arburg 270 E injection moulding machine.

[0268] MVR is determined in accordance with ISO 1133 (2012 version) at 240° C., using 5 kg ram loading. Table 1 indicates this value as “MVR value of starting sample”.

[0269] The change in MVR during storage of the granulate for 5 days at 95° C. and 100% relative humidity serves as measure of hydrolysis resistance.

[0270] Impact resistance (weld line strength) is determined on test specimens measuring 80 mm×10 mm×4 mm at 23° C. in accordance with ISO 179/1eU (2010 version).

[0271] Melt viscosity is determined according to ISO 11443 (2014 version) at a temperature of 260° C. and a shear rate of 1000 s.sup.−1.

[0272] Tensile strain at break is determined at room temperature in accordance with ISO 527 (1996 version).

[0273] Flame retardancy is assessed on strips measuring 127×12.7×1.5 mm in accordance with UL94V.

[0274] Resistance to environmental stress cracking (ESC) in toluene/isopropanol (60/40 parts by volume) at room temperature serves as measure of chemicals resistance. A test specimen measuring 80 mm×10 mm×4 mm injection-moulded at melt temperature 260° C. is subjected to 2.4% external outer fibre strain by means of a clamping template and completely immersed in the liquid, and the time required for fracture failure induced by environmental stress cracking is determined. The test method is based on ISO 22088 (2006 version).

[0275] The content of free bisphenol A monomer was determined by means of high-performance liquid chromatography (HPLC) with a diode array (DAD) detector on the pellets produced by means of a twin-screw extruder. For this purpose, the pellets were first dissolved in dichloromethane and then the polycarbonate was reprecipitated with acetone/methanol. The precipitated polycarbonate and all components of the compositions that are insoluble in the reprecipitant were filtered off, and the filtrates were then concentrated almost to dryness on a rotary evaporator. The residues were analysed by means of HPLC-DAD at room temperature (gradient: acetonitrile/water; stationary phase C-18).

TABLE-US-00001 TABLE 1 Moulding compounds and properties thereof 1 7 (comp.) 2 3 4 5 6 (comp.) Components [parts by weight] A 76.00 75.65 75.30 74.60 73.90 71.80 86.2 B.1 7.70 7.70 7.70 7.70 7.70 7.70 5.50 B.2 4.70 4.55 4.40 4.10 3.80 2.90 2.00 C — 0.50 1.00 2.00 3.00 6.00 — D 10.00 10.00 10.00 10.00 10.00 10.00 5.00 E-1 0.80 0.80 0.80 0.80 0.80 0.80 0.80 E-2 0.40 0.40 0.40 0.40 0.40 0.40 0.40 E-3 0.10 0.10 0.10 0.10 0.10 0.10 0.10 E-4 0.30 0.30 0.30 0.30 0.30 0.30 — Properties Weld line strength 46.7 53.2 55.7 56.7 57.2 57.8 48.2 [kJ/m.sup.2] Tensile strain at break 102 112 114 117 120 125 105 [%] UL94V assessment at V0 V0 V0 V0 V0 V0 V0 1.5 mm Toal AFT [s] 39 34 23 20 15 12 35 (after storage at 70° C. for 7 days) ESC-characteristics in 02:46 04:11 4:37 5:00 5:00 5:00 3:25 toluene/isopropanol no no [fracture after min:sec] fracture fracture Melt viscosity 245 270 300 320 336 352 355 260° C./1000 s−1 [Pas] MVR after storage (5 20.8 18.31 16.5 14.7 12.8 11.3 16.3 days) [cm.sup.3/10 min] Residual BPA content 25 21 19 16 13 10 32 [ppm] 11 8 9 10 (comp.) 12 13 14 Components [parts by weight] A 85.50 84.10 82.00 63.70 63.00 61.60 59.50 B.1 5.50 5.50 5.50 10.00 10.00 10.00 10.00 B.2 1.70 1.10 0.20 10.00 9.70 9.10 8.20 C 1.00 3.00 6.00 — 1.00 3.00 6.00 D 5.00 5.00 5.00 15.00 15.00 15.00 15.00 E-1 0.80 0.80 0.80 0.80 0.80 0.80 0.80 E-2 0.40 0.40 0.40 0.40 0.40 0.40 0.40 E-3 0.10 0.10 0.10 0.10 0.10 0.10 0.10 E-4 — — — — — — — Properties Weld line strength 52.3 55.4 60.1 6.5 7.1 7.9 8.5 [kJ/m.sup.2] Tensile strain at break 109 117 121 52 63 75 83 [%] UL94V assessment at V0 V0 V0 V0 V0 V0 V0 1.5 mm Toal AFT [s] 30 22 15 30 23 19 13 (after storage at 70° C. for 7 days) ESC-characteristics in 4:35 5:00 5:00 3:10 4:25 5:00 5:00 toluene/isopropanol no [fracture after min:sec] fracture Melt viscosity 381 419 441 139 162 185 207 260° C./1000 s−1 [Pas] MVR after storage (5 14.9 13.3 12.5 28.0 22.2 19.5 17.9 days) [cm.sup.3/10 min] Residual BPA content 25 17 12 46 39 30 24 [ppm]

[0276] The examples from Table 1 show that only the compositions comprising the inventive proportion of epoxy-containing vinyl copolymer achieve a good combination of high elongation at break, good weld line strength, high chemical stability in the ESC test, short afterflame time in the flame test, a lower residual BPA content and good hydrolysis stability.

[0277] A particularly favourable profile of properties is achieved when the proportion of component C is in the range from 3.0% to 6.0% by weight. The properties mentioned are improved to the greatest degree and the increase in the melt viscosity is still within an acceptable range.