FLAME-RESISTANT POLYCARBONATE-POLYESTER BLEND

Abstract

The present invention relates to a molding compound containing A) 45 to 65 wt. % of at least one aromatic polycarbonate, polyester carbonate or mixtures thereof, B) 18 to 31 wt. % of at least one polybutylene terephthalate having rheological properties of 5 g/10 min to 30 g/10 min determined according to DIN EN ISO 1133 at 250° C. measuring temperature and a load of 2.16 kg, C) 3 to 10 wt % of at least one rubber-modified graft polymer with a graft base consisting of a silicone-acrylate composite rubber and a silicone rubber content of 20 to 60 wt. % relative to the graft base, D) 8 to 13 wt. % of at least one phosphazene, and E) 0 to 8.0 wt. % of at least one polymer additive, the weight ratio of components D to C) being in the range of 1.3:1 to 2.5:1. The invention also relates to a method for producing the molding compound, to the use of the molding compound for producing moldings and to the moldings as such.

Claims

1. A thermoplastic molding compound comprising A) 45% to 65% by weight of at least one of an aromatic polycarbonate, polyestercarbonate,. and mixtures thereof, B) 18% by weight to 31% by weight of at least one polybutylene terephthalate having a flowability of 5 g/10 min to 30 g/10 min to DIN EN ISO 1133 at measurement temperature 250° C. and a load of 2.16 kg, C) 3% to 10% by weight of at least one rubber-modified graft polymer having a graft base comprising a silicone-acrylate composite rubber and a silicone rubber content of 20% to 60% by weight based on the graft base, D) 8% to 13% by weight of at least one phosphazene, E) 0% to 8.0% by weight of at least one polymer additive, wherein the weight ratio of components D) to C) is from 1.3:1 to 2.5:1.

2. The molding compound as claimed in claim 1, characterized in that component A is a linear polycarbonate based on bisphenol A.

3. The molding compound as claimed in claim 1, characterized in that component A has a weight-average molecular weight M.sub.w, determined by gel permeation chromatography in methylene chloride with polycarbonate based on bisphenol A as standard, of 28 000 to 33 000 g/mol.

4. The molding compound as claimed in claim 1, characterized in that component B has a flowability measured as MFR of 9 g/10 min to 15 g/10 min at measurement temperature 250° C. and a load of 2.16 kg to DIN EN ISO 1133.

5. The molding compound as claimed in claim 1, characterized in that component C is a graft polymer comprising C.1 8% to 20% by weight, based on component C, of at least one vinyl monomer onto C.2 92% to 80% by weight based on component C of a graft base composed of silicone-acrylate composite rubber.

6. The molding compound as claimed in claim 5, characterized in that C.1 is methyl methacrylate.

7. The molding compound as claimed in claim 1, characterized in that the graft base of component C includes a silicone rubber content of 25% to 50% by weight, based on the graft base.

8. The molding compound as claimed in claim 1, characterized in that component D is a cyclic phenoxyphosphazene of formula (V) ##STR00008## where k is an integer from 1 to 10.

9. The molding compound as claimed in claim 8, wherein the trimer content (k=1) is 60 to 100 mol %, based on component D.

10. The molding compound as claimed in claim 1, characterized in that the weight ratio of component D to component C is 2:1 to 2.5:1.

11. The molding compound as claimed in claim 1, comprising 50% to 62% by weight of component A, 20% to 30% by weight of the component B, 4% to 9% by weight of the component C, 9% to 12% by weight of component D and 0.2% to 3% by weight of the component E.

12. The molding compound as claimed in claim 1, consisting of components A to E.

13. A process for producing a molding compound as claimed in claim 1, characterized in that components A to E are mixed with one another at a temperature of 200 to 320° C. cooled, and pelletized.

14. In a process for production of molded articles, the improvement comprising including the molding compound as claimed in claim 1.

15. A molded article comprising a molding compound as claimed in claim 1.

Description

Production of the Molding Compounds and Molded Articles

[0117] The thermoplastic molding compounds can be produced, for example, by mixing the respective constituents in a known manner and melt-compounding and melt-extruding the mixture at temperatures of preferably 200° C. to 320° C., more preferably at 220° C. to 290° C., most preferably at 230° C. to 270° C., in customary apparatuses such as internal kneaders, extruders and twin-screw extruders for example. This process is generally referred to in the context of the present application as compounding.

[0118] The term “molding compound” is understood to mean the product obtained when the respective components are melt-compounded and melt-extruded.

[0119] The individual constituents of the molding compounds can be mixed in a known manner, either successively or simultaneously, either at about 20° C. (room temperature) or at higher temperature. This means that, for example, some of the constituents may be introduced via the main intake of an extruder and the remaining constituents may be introduced later in the compounding process via a side extruder.

[0120] The molding compounds of the invention may be used to produce molded articles of any kind. These may be produced by injection molding, extrusion and blow molding processes for example. A further form of processing is the production of molded articles by thermoforming from previously produced sheets or films. The molding compounds of the invention are particularly suitable for processing by injection molding, extrusion, blow molding and thermoforming methods. Most preferred is the injection molding method.

[0121] It is also possible to meter the constituents of the molding compound directly into an injection molding machine or into an extrusion unit and to process them to give molded articles.

[0122] Examples of such molded articles that are producible from the molding compound of the invention are films, profiles, housing parts of any kind, for example for domestic appliances such as juice presses, coffee machines, mixers; for office machinery such as monitors, flatscreens, notebooks, printers, copiers; sheets, pipes, electrical installation ducts, windows, doors and other profiles for the construction sector (interior fitout and exterior applications) and also electrical and electronic components such as switches, plugs and sockets, and parts for commercial vehicles, in particular for the automotive sector. The compositions and molding compounds of the invention are also suitable for producing the following molded articles or moldings: interior fitout parts for rail vehicles, ships, aircraft, buses and other motor vehicles, bodywork components for motor vehicles, housings of electrical equipment containing small transformers, housings for equipment for the processing and transmission of information, massage equipment and housings therefor, toy vehicles for children, two-dimensional wall elements, housings for safety equipment, thermally insulated transport containers, molded parts for sanitation and bath equipment, protective grilles for ventilation openings and housings for garden equipment. The molding compounds of the invention are particularly suitable for production of housings and facings for medical equipment.

EXAMPLES

Component A

[0123] Linear polycarbonate based on bisphenol A and having a weight-average molecular weight M.sub.w of 31 000 g/mol (determined by GPC in methylene chloride with polycarbonate based on bisphenol A as standard).

Component B-1

[0124] Polybutylene terephthalate having a melt flow rate (MFR) of 12.0 g/10 min, measured to DIN EN ISO 1133 (2012 version) at 250° C. and load 2.16 kg.

Component B-2

[0125] Polybutylene terephthalate having a melt flow rate (MFR) of 49.0 g/10 min, measured to DIN EN ISO 1133 (2012 version) at 250° C. and load 2.16 kg.

Component B-3

[0126] Polyethylene terephthalate (PET) having an intrinsic viscosity of 0.87 dl/g, measured in dichloroacetic acid in a concentration of 1% by weight at 25° C.

Component C-1

[0127] Graft polymer composed of 14% by weight of methyl methacrylate onto 86% by weight of a silicone-acrylate composite rubber as graft base, where the silicone-acrylate composite rubber contains 36% by weight of silicone rubber and 64% by weight of polyalkyl(meth)acrylate rubber and where there is interpenetration of the two rubber components mentioned in the composite rubber, such that they are essentially inseparable.

Component C-2

[0128] Graft polymer prepared by reaction of 11% by weight of methyl methacrylate onto 89% by weight of a silicone-acrylate composite rubber as graft base, wherein the silicone-acrylate composite rubber contains 92% by weight of silicone rubber and 8% by weight of polyalkyl(meth)acrylate rubber and where there is interpenetration of the two rubber components mentioned in the composite rubber, such that they are essentially inseparable.

Component C-3

[0129] Graft polymer composed of 17% by weight of methyl methacrylate onto 83% by weight of a silicone-acrylate composite rubber as graft base, where the silicone-acrylate composite rubber contains 11% by weight of silicone rubber and 89% by weight of polyalkyl(meth)acrylate rubber and where there is interpenetration of the two rubber components mentioned in the composite rubber, such that they are essentially inseparable.

Component C-4

[0130] Graft polymer composed of 23% by weight of methyl methacrylate and 6% by weight of styrene onto 71% by weight of butadiene rubber as graft base.

Component D

[0131] Phenoxyphosphazene of the formula (VI) having a fraction of oligomers where k=1 of 70 mol %, a proportion of fraction where k=2 of 18 mol % and a fraction of oligomers where k>3 of 12 mol %.

##STR00007##

Component E-1

[0132] Cycolac™ INP449: polytetrafluoroethylene (PTFE) preparation from Sabic, composed of 50% by weight of PTFE present in an SAN copolymer matrix.

Component E-2

[0133] Irganox™ 1010 (pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate); BASF (Ludwigshafen, Germany)

Component E-3

[0134] Irgafox™ 168 (tris(2,4-di-tert-butylphenyl) phosphite); BASF (Ludwigshafen, Germany)

Component E-4

[0135] phosphorous acid, H.sub.3PO.sub.3, Sigma-Aldrich Chemie GmbH, Germany

Component E-5

[0136] pentaerythritol tetrastearate as demolding agent, Cognis Oleochemicals GmbH, Germany

Production and Testing of the Molding Compounds of the Invention

[0137] The components were mixed in a Werner & Pfleiderer ZSK-25 twin-screw extruder at a melt temperature of 260-280° C. The molded articles were produced at a melt temperature of 260° C. (or at 270° C. in the case of V22 owing to the higher melting temperature of PET) and a mold temperature of 70° C. on an Arburg 270 E injection molding machine.

[0138] Tensile modulus of elasticity was determined to ISO 527 (1996 version) at room temperature.

[0139] IZOD notched impact resistance was determined at room temperature on test specimens of dimensions 80 mm×10 mm×4 mm to ISO 180-A (1982 version).

[0140] Impact resistance was determined at room temperature on test specimens of dimensions 80 mm×10 mm×4 mm to ISO 180-U (1982 version).

[0141] Melt viscosity as a measure of melt flowability was determined to ISO 11443 (2014 version) at a temperature of 260° C. and a shear rate of 1000 s.sup.−1. In the case of V22, measurement was effected at 270° C. owing to the higher melting temperature of PET.

[0142] Melt volume flow rate (MVR) was measured to ISO 1133 (2012 version) at a temperature of 260° C. (or at 270° C. in the case of V22) and a load of 5 kg.

[0143] Flame retardancy was assessed to UL94V on specimens of dimensions 127×12.7×2.4 mm

[0144] A measure used for chemical stability was stress cracking (ESC) resistance in various media at room temperature. What was determined was the time taken for stress-induced failure resulting from the occurrence of edge cracks or complete fracture on a test specimen of dimensions 80 mm×10 mm×4 mm that had been injection-molded at melt temperature 260° C. (or 270° C. in the case of V22), which was subjected to an external outer fiber strain 1.2% or 2.4% by means of a clamping template and completely immersed in the liquid. Measurement was in accordance with ISO 22088 (2006 version). Media used were rapeseed oil and the detergents Cidex™ OPA (Johnson & Johnson Medical Ltd., UK) and Hexaquart™plus (BBraun, Germany). The maximum test duration is 168 h. If no edge cracks or fracture of the test specimen have been observed within this period, the test is considered to have been passed (resistant).

[0145] Cidex™ OPA is a detergent and disinfectant which is used particularly for the cleaning of medical equipment and instruments. The active ingredient of Cidex™ OPA is ortho-phthalaldehyde in a concentration of 0.55%.

[0146] Hexaquart™ plus is a concentrate for cleaning and disinfection of surfaces in the medical sector. Active ingredients of the detergent are didecyldimethylammonium chloride (6.0 g per 100 g) and N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine (5.5 g per 100 g). A solution having the manufacturer's recommended concentration of 2% by volume in water was produced from the concentrate and used as test medium.

TABLE-US-00001 TABLE 1 Compositions of the inventive molding compounds and their properties 1 2 3 4 5 6 Components [% by weight] A 52.90 50.95 60.90 52.90 54.20 49.65 B-1 28.48 27.43 20.48 28.48 29.18 26.73 C-1 5.00 8.00 5.00 5.00 5.00 8.00 D 12.00 12.00 12.00 12.00 10.00 14.00 E-1 0.80 0.80 0.80 0.80 0.80 0.80 E-2 0.10 0.10 0.10 0.10 0.10 0.10 E-3 0.10 0.10 0.10 0.10 0.10 0.10 E-4 0.02 0.02 0.02 0.02 0.02 0.02 E-5 0.60 0.60 0.60 0.60 0.60 0.60 D/C ratio 2.4 1.5 2.4 2.4 2.0 1.75 Properties MVR [cm.sup.3/10 min] 32 28 31 31 28 34 Melt viscosity [Pas] 256 253 273 255 280 227 Tensile modulus of elasticity [MPa] 2337 2171 2360 2337 2338 2172 Izod impact resistance [kJ/m.sup.2] n.f. n.f. n.f. n.f. n.f. n.f. Izod notched impact resistance [kJ/m.sup.2] 46 61 52 49 51 58 UL94-V (2.4 mm) V-0 V-0 V-0 V-0 V-0 V-0 ESC resistance rapeseed oil, 2.4% OFS resistant Cidex ™ OPA, 2.4% OFS resistant Hexaquart ™ plus, 1.2% OFS resistant *n.f.: no fracture

TABLE-US-00002 TABLE 2 Compositions of the noninventive molding compounds and their properties V7 V8 V9 V10 V11 V12 Components [% by weight] A 52.90 50.95 52.90 50.95 52.90 50.95 B-1 28.48 27.43 28.48 27.43 28.48 27.43 C-2 5.00 8.00 C-3 5.00 8.00 C-4 5.00 8.00 D 12.00 12.00 12.00 12.00 12.00 12.00 E-1 0.80 0.80 0.80 0.80 0.80 0.80 E-2 0.10 0.10 0.10 0.10 0.10 0.10 E-3 0.10 0.10 0.10 0.10 0.10 0.10 E-4 0.02 0.02 0.02 0.02 0.02 0.02 E-5 0.60 0.60 0.60 0.60 0.60 0.60 D/C ratio 2.4 1.5 2.4 2.4 2.4 1.5 Properties MVR [cm.sup.3/10 min] 29 25 28 26 28 25 Melt viscosity [Pas] 253 250 269 261 277 272 Tensile modulus of elasticity [MPa] 2411 2263 2420 2249 2352 2226 Izod impact resistance [kJ/m.sup.2] n.f. n.f. n.f. n.f. n.f. n.f. Izod notched impact resistance [kJ/m.sup.2] 13 58 31 63 11 36 UL94-V (2.4 mm) V- V-1 V- V- V- V- NOT NOT NOT NOT NOT n.f.: no fracture V-NOT: no UL classification, failed

TABLE-US-00003 TABLE 3 Compositions of the noninventive molding compounds and their properties V13 V14 V15 V16 V17 V18 V19 Components [% by weight] A 49.00 52.25 51.60 56.77 48.90 40.90 65.025 B-1 26.38 28.13 27.78 30.57 32.48 40.48 16.260 C-1 11.00 8.00 5.00 5.00 5.00 5.00 5.00 D 12.00 10.00 14.00 6.00 12.00 12.00 12.00 E-1 0.80 0.80 0.80 0.80 0.80 0.80 0.80 E-2 0.10 0.10 0.10 0.15 0.10 0.10 0.20 E-3 0.10 0.10 0.10 0.10 0.10 0.10 0.10 E-4 0.02 0.02 0.02 0.01 0.02 0.02 0.015 E-5 0.60 0.60 0.60 0.60 0.60 0.60 0.60 D/C ratio 1.09 1.25 2.8 1.2 2.4 2.4 2.4 Properties MVR [cm.sup.3/10 min] 25 24 37 22 34 33 31 Melt viscosity [Pas] 248 277 227 338 238 239 291 Tensile modulus of elasticity [MPa] 2045 2199 2323 2377 2362 2347 2278 Izod impact resistance [kJ/m.sup.2] n.f. n.f. n.f. n.f. n.f. n.f. n.f. Izod notched impact resistance [kJ/m.sup.2] 60 62 17 58 14 12 68 UL94-V (2.4 mm) V-1 V- V-1 V-1 V-0 V-0 V-0 NOT ESC resistance rapeseed oil, 2.4% OFS resistant Cidex ™ OPA, 2.4% OFS resistant Hexaquart ™ plus, 1.2% OFS edge cracks after 118.5 h n.f.: no fracture V-NOT: no UL classification, failed

TABLE-US-00004 TABLE 4 Compositions of the noninventive molding compounds and their properties V20 V21 V22 Components [% by weight] A 52.90 52.90 52.81 B-1 18.98 B-2 9.50 28.48 B-3 28.48 C-1 5.00 5.00 5.00 D 12.00 12.00 12.00 E-1 0.80 0.80 0.80 E-2 0.10 0.10 0.20 E-3 0.10 0.10 0.10 E-4 0.02 0.02 0.02 E-5 0.60 0.60 0.60 D/C ratio 2.4 2.4 2.4 Properties MVR [cm.sup.3/10 min] 41 48  48 (270° C.) Melt viscosity [Pas] 224 200 132 (270° C.) Tensile modulus of 2335 2354 2383 elasticity [MPa] Izod impact n.f. n.f. n.f. resistance [kJ/m.sup.2] Izod notched impact 13 15 24 resistance [kJ/m.sup.2] UL94-V (2.4 mm) V-0 V-0 V-0 ESC resistance rapeseed oil, 2.4% OFS resistant Cidex ™ OPA, 2.4% OFS resistant Hexaquart ™ plus, 1.2% OFS fracture at <168 h n.f.: no fracture

[0147] The data from tables 1 to 4 show that only the inventive molding compounds have the desired property profile of mechanical properties, especially impact resistance and notched impact resistance, flowability and flame retardancy. Molding compounds 1, 3, 4 and 5 additionally show the preferably desired stiffness.

[0148] If a noninventive graft polymer is used (V7 to V12), flame retardancy and in some cases also toughness are not at the required level.

[0149] If the weight ratio of components D to C is not within the claimed range (V13 to V16), flame retardancy is likewise inadequate. Moreover, in the case of too high a ratio, toughness is limited.

[0150] If the proportion of component B is too high, toughness is distinctly limited (V17 and V18). By contrast, if the proportion is too low, resistance to detergents is limited, i.e. there is not resistance against all detergents.

[0151] It is also disadvantageous when component B has excessive flowability (V20 and V21) or when a polyethylene terephthalate is used rather than polybutylene terephthalate (V22).