POLYCARBONATE COMPOSITION WITH GOOD FLAME RETARDANCY

Abstract

The invention relates to a composition for production of a thermoplastic moulding compound, wherein the composition comprises or consists of the following constituents: A) 50-90% by weight of aromatic polycarbonate or polyestercarbonate having a relative solution viscosity of at least 1.285, measured in CH.sub.2Cl.sub.2 as solvent at 25° C. and a concentration of 0.5 g/100 ml, B) 1-10% by weight of rubber-modified graft polymer, C) 2.5-10% by weight of boron nitride, D) 4-20% by weight of talc, E) 2-20% by weight of phosphorus-containing flame retardant, F) 0-20% by weight of further additives, and to a process for producing the thermoplastic moulding compound, to the moulding compound itself, to the use of the moulding compound for production of mouldings and to the mouldings themselves.

Claims

1. A thermoplastic moulding composition comprising: A) 50-90% by weight of aromatic polycarbonate or polyestercarbonate having a relative solution viscosity of at least 1.285, measured in CH.sub.2Cl.sub.2 as solvent at 25° C. and a concentration of 0.5 g/100 ml, B) 1-10% by weight of rubber-modified graft polymer, C) 2.5-10% by weight of boron nitride, D) 4-20% by weight of talc, E) 2-20% by weight of phosphorus-containing flame retardant, and F) 0-20% by weight of further additives.

2. The composition of claim 1, wherein component A is a branched polycarbonate based on bisphenol A.

3. The composition of claim 1, comprising, as component B, one or more graft polymers of: B.1 5% to 95% by weight of at least one vinyl monomer, onto B.2 95% to 5% by weight of at least one graft base selected from the group consisting of diene rubbers, EP(D)M rubbers, acrylate rubbers, polyurethane rubbers, silicone rubbers, chloroprene rubbers, ethylene/vinyl acetate rubbers, and silicone/acrylate composite rubbers.

4. The composition of claim 3, wherein the graft base B.2 is a silicone-acrylate composite rubber composed of mutually penetrating silicone rubber and polyalkyl(meth)acrylate rubber, wherein the proportion of silicone rubber is 50-95% by weight based on B.2.

5. The composition of claim 1, wherein component C is hexagonal boron nitride.

6. The composition of claim 1, wherein component C has a median particle size D50 of 0.1 to 50 μm, determined by laser diffraction.

7. The composition of claim 1, wherein component D has an average particle size d.sub.50 of 0.7 to 2.5 μm determined by sedimentation analysis.

8. The composition of claim 1, wherein component E is at least one flame retardant selected from the group comprising oligophosphate, phosphazene and salts of phosphinic acid.

9. The composition of claim 8, wherein component E is a compound having the following structure: ##STR00011##

10. The composition of claim 1, wherein component F comprises at least one additive selected from the group consisting of lubricants, mould release agents, antidripping agents, nucleating agents, antistats, conductivity additives, stabilizers, flowability promoters, compatibilizers, further impact modifiers other than component B, further polymeric blend partners, fillers and reinforcers other than component D, and dyes and pigments.

11. The composition of claim 1, wherein component F is zinc borate hydrate Zn.sub.2B.sub.6O.sub.11. 3.5H.sub.2O.

12. The composition of claim 1, comprising: 55-80% by weight of component A, 1-8% by weight of component B, 2.5-8% by weight of component C, 5-15% by weight of component D, 3-15% by weight of component E, and 0.1-10% by weight of component F.

13. (canceled)

14. A molded article comprising the composition of claim 1.

15. The molded article of claim 14 having a tensile modulus of elasticity of at least 4000 MPa measured to ISO 527, heat release according to ISO 5660-1 of not more than 90 kW/m.sup.2, a smoke gas density to ISO 5659-2 of Ds(4) not more than 300 and VOF4 of not more than 600, and a time before fracture in the ESC test in rapeseed oil at an edge fibre elongation of 2.4% of at least two hours.

16. The molded article of claim 14, wherein the article is injection molded or thermoform molded.

Description

EXAMPLES

[0228] Component A-1

[0229] Branched polycarbonate based on bisphenol A and having a relative solution viscosity of η.sub.rcl=1.325, measured in CH.sub.2Cl.sub.2 as solvent at 25° C. and a concentration of 0.5 g/100 ml, which has been branched by use of 0.4% by weight of THPE (1,1,1-tris(p-hydroxyphenyl)ethane) based on the sum total of bisphenol A and THPE.

[0230] Component A-2

[0231] Linear polycarbonate based on bisphenol A and having a relative solution viscosity of η.sub.rcl=1.32, measured in CH.sub.2Cl.sub.2 as solvent at 25° C. and a concentration of 0.5 g/100 ml.

[0232] Component A-3

[0233] Linear polycarbonate based on bisphenol A and having a relative solution viscosity of η.sub.rcl=1.29, measured in CH.sub.2Cl.sub.2 as solvent at 25° C. and a concentration of 0.5 g/100 ml.

[0234] Component A-4

[0235] Linear polycarbonate based on bisphenol A and having a relative solution viscosity of η.sub.rcl=1.28, measured in CH.sub.2Cl.sub.2 as solvent at 25° C. and a concentration of 0.5 g/100 ml.

[0236] Component B-1

[0237] Impact modifier, graft polymer of [0238] B-1.1 11% by weight of methyl methacrylate onto [0239] B-1.2 89% by weight of a silicone-acrylate composite rubber as graft base, where the silicone-acrylate rubber contains [0240] B-1.2.1 92% by weight of silicone rubber and [0241] B-1.2.2 8% by weight of polyalkyl(meth)acrylate rubber, and [0242] where these two rubber components B.2.1 and B.2.2 penetrate one another in the composite rubber, such that they are essentially inseparable from one another.

[0243] Component B-2

[0244] Impact modifier, graft polymer of [0245] B-2.1 17% by weight of methyl methacrylate onto [0246] B-2.2 83% by weight of a silicone-acrylate composite rubber as graft base, where the silicone-acrylate rubber contains [0247] B-2.2.1 11% by weight of silicone rubber and [0248] B-2.2.2 89% by weight of polyalkyl(meth)acrylate rubber, and [0249] where these two rubber components B.2.1 and B.2.2 penetrate one another in the composite rubber, such that they are essentially inseparable from one another.

[0250] Component B-3

[0251] Impact modifier, ABS graft polymer with core-shell structure, prepared by emulsion polymerization of 43% by weight based on the ABS polymer of a mixture of 27% by weight of acrylonitrile and 73% by weight of styrene in the presence of 57% by weight based on the ABS polymer of a particulate-crosslinked polybutadiene rubber (median particle diameter d.sub.50=0.35 μm).

[0252] Component B-4

[0253] Impact modifier, MBS graft polymer with core-shell structure, prepared by emulsion polymerization of 24% by weight of methyl methacrylate in the presence of 76% by weight based on the MBS polymer of a particulate-crosslinked copolymer of 88% by weight of butadiene and 12% by weight of styrene.

[0254] Component B-5

[0255] Impact modifier, MB graft polymer with core-shell structure, prepared by emulsion polymerization of 25% by weight of methyl methacrylate in the presence of 75% by weight based on the MB polymer of a particulate-crosslinked polybutadiene rubber.

[0256] Component B-6

[0257] Impact modifier, graft polymer with core-shell structure, prepared by emulsion polymerization of 40% by weight of methyl methacrylate in the presence of 60% by weight based on the graft polymer of a particulate-crosslinked poly-n-butylacrylate rubber (median particle diameter d.sub.50=0.50 μm).

[0258] Component C

[0259] Hexagonal boron nitride; (BN, CAS No. 10043-11-5) having a median particle size D50=16 μm, a purity of >97% by weight, a carbon content of <0.1% by weight and a BET surface area of 8 m.sup.2/g.

[0260] Component D

[0261] Talc, Jetfine 3CA from Imerys with an MgO content of 32% by weight, an SiO.sub.2 content of 61% by weight and an Al.sub.2O.sub.3 content of 0.3% by weight, median particle size d.sub.50=1.0 μm.

[0262] Component E-1

[0263] Bisphenol-A-based oligophosphate having a phosphorus content of 8.9% by weight.

##STR00009##

[0264] Component E-2

[0265] Phenoxyphosphazene of formula (a) with 70% by weight n=1 and 30% by weight n=2-10.

##STR00010##

[0266] Component E-3

[0267] Phoslite MB 9545, masterbatch composed of 45% by weight of calcium phosphinate and 55% by weight of aromatic, bisphenol A-based polycarbonate (manufacturer: Italmatch Chemicals).

[0268] Component F-1

[0269] Zinc borate hydrate (Zn.sub.2B.sub.6O.sub.11 3.5H.sub.2O, CAS No. 138265-88-0)

[0270] Component F-2

[0271] Teflon PTFE CFP 6000 X, polytetrafluoroethylene powder (manufacturer: Chemours)

[0272] Component F-3

[0273] Pentaerythritol tetrastearate as lubricant/demoulding agent

[0274] Component F-4

[0275] Heat stabilizer, Irganox™ B900

[0276] (mixture of 80% Irgafos® 168 (tris(2,4-di-tert-butylphenyl) phosphite) and 20% Irganox™ 1076 (2,6-di-tert-butyl-4-(octadecanoxycarbonylethyl)phenol) (manufacturer: BASF AG)

[0277] Production and Testing of the Moulding Compounds

[0278] In a twin-screw extruder (Werner und Pfleiderer ZSK-25), the feedstocks listed in Table 1 are compounded and pelletized at a speed of 225 rpm and a throughput of 20 kg/h at a machine temperature of 260° C.

[0279] The finished pelletized materials are processed in an injection-moulding machine to give the appropriate specimens (melt temperature 240° C., mould temperature 80° C., flow front speed 240 mm/s).

[0280] Characterization is effected to ISO 180/1U (1982 version, Izod impact resistance), ISO 527 (1996 version, tensile modulus of elasticity), ISO 306 (2013 version, Vicat softening temperature, Method B with load 50 N and a heating rate of 120 K/h), ISO 11443 (2014 version, melt viscosity) and ISO 1133 (2012 version, melt volume flow rate (MVR) at 260° C./5 kg). A measure used for the chemical resistance of the compositions produced is the environmental stress cracking (ESC) test according to DIN EN ISO 22088 (2006 version), which is conducted as follows: with rapeseed oil as test medium, exposure at 2.4% edge fibre elongation; in other words, the duration at which fracture of the test specimen (test bar of dimensions 80×10×4 mm) occurs is ascertained and reported.

[0281] The heat release is tested on test specimens of thickness 3 mm to ISO 5660-1:2015 (cone calorimeter) at irradiation intensity 50 kW/m.sup.2; the MARHE (=maximum average rate of heat emission) value is determined. For classification in hazard level 2 (HL2) according to specification set R1/R6 of the European rail vehicles standard EN45545-2:2013, an MARHE value of 90 kW/m.sup.2 must not be exceeded.

[0282] Smoke gas evolution is measured on test specimens of thickness 3 mm in accordance with ISO 5659-2:2006 at an irradiation intensity of 50 kW/m.sup.2 without an ignition flame, for the determination of Ds(4) and VOF 4. For classification in hazard level 2 (HL2) according to specification set R1/R6 of the European rail vehicles standard EN45545-2:2013, a D(s)4 value of 300 and a VOF 4 value of 600 min must not be exceeded.

[0283] It is apparent from Table 1 that the compositions of Examples 3-7, 9-11, 14-21 and 24-35 achieve the object of the invention, i.e. a combination of high modulus of elasticity (at least 4000 MPa) and good chemical stability (time before fracture with rapeseed oil at least 2 h, with edge fibre elongation 2.4%) with simultaneously low heat release according to ISO 5660-1:2015 (MARHE max. 90 kW/m.sup.2) and low smoke gas density to ISO 5659-2:2006 (Ds(4) max. 300 and VOF4 max. 600 min).

[0284] The properties of the compositions of Examples 1-5 show that at least 2.5% by weight of boron nitride must be present.

[0285] Examples 5-8 show that, as well as branched polycarbonate, it is also possible to use linear polycarbonate based on bisphenol A when it has a greater relative solution viscosity than η.sub.rcl=1.28, measured in CH.sub.2Cl.sub.2 as solvent at 25° C. and a concentration of 0.5 g/100 ml.

[0286] Examples 9-13 show that at least 1.0% by weight of an impact modifier must be used, the chemical nature of the impact modifier being variable (Examples 14-18).

[0287] The properties of the compositions of Examples 19-23 show that at least 4% by weight of talc must be used. The use of zinc borate hydrate is optional (Examples 24-27).

[0288] Examples 28-35 show that both the content and the chemical nature of the phosphorus-containing flame retardant are variable.

TABLE-US-00001 TABLE 1 Composition and properties of the moulding compounds Feedstock 1 2 8 (% by wt.) (comp.) (comp.) 3 4 5 6 7 (comp.) A-1 71 70 69 68 67 A-2 67 A-3 67 A-4 67 B-1 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 C 1 2 3 4 5 5 5 5 D 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 E-1 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 F-1 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 F-2 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 F-3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 F-4 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Test Condition Standard Unit Izod impact 23° C. ISO kJ/m.sup.2 140 109 84 71 78 92 70 42 resistance 180/1 U Tensile 1 mm/min ISO MPa 3755 3984 4150 4281 4436 4472 4198 4396 modulus 527-1, -2 Vicat 50N; ISO ° C. 112 111 111 110 109 108 108 107 softening 120° C./h 306 temperature Viscosity function Melt 260° C. ISO Pas 1180 1176 1125 1116 1017 880 642 422 viscosity 11443 [100 s − 1] Melt 260° C. ISO Pas 421 415 392 393 395 386 319 227 viscosity 11443 [1000 s − 1] Melt 260° C. ISO Pas 325 319 304 305 306 299 254 193 viscosity 11443 [1500 s − 1] Melt 260° C.; ISO cm3/ 7.5 7.6 7.6 7.8 7.9 12.4 17.9 28.0 volume 5 kg 1133 (10 min) flow rate (MVR) ESC in rapeseed oil Time until 2.4% edge ISO h 21 20 16 15 23 23 2.3 0.3 fracture fibre 4599 elongation Heat 50 kW/m.sup.2 ISO kW/m.sup.2 83 71 64 70 59 47 50 57 release 5660-1 (3 mm) MARHE Smoke gas 50 kW/m.sup.2 ISO density without 5659-2 (3 mm) ignition flame Ds(4) 212 239 203 169 167 207 205 185 VOF4 min 432 404 322 301 324 352 340 277 Feedstock 12 13 (% by wt.) 9 10 11 (comp.) (comp.) 14 15 16 17 18 A-1 68 69 70 71 71.5 67 67 67 67 67 B-1 3.5 2.5 1.5 0.5 0 B-2 4.5 B-3 4.5 B-4 4.5 B-5 4.5 B-6 4.5 C 5 5 5 5 5 5 5 5 5 5 D 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 E-1 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 F-1 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 F-2 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 F-3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 F-4 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Test Condition Standard Unit Izod impact 23° C. ISO kJ/m.sup.2 76 57 38 31 27 74 47 49 44 41 resistance 180/1 U Tensile 1 mm/min ISO MPa 4473 4637 4954 5189 5495 4662 4903 4812 4755 4811 modulus 527-1, -2 Vicat 50N; ISO ° C. 110 111 111 110 108 110 110 110 110 111 softening 120° C./h 306 temperature Viscosity function Melt 260° C. ISO Pas 1102 1066 915 626 403 1183 995 1014 1037 1043 viscosity 11443 [100 s − 1] Melt 260° C. ISO Pas 401 401 362 274 201 423 382 391 401 385 viscosity 11443 [1000 s − 1] Melt 260° C. ISO Pas 310 313 285 222 169 327 298 304 313 298 viscosity 11443 [1500 s − 1] Melt 260° C.; ISO cm3/ 8.5 8.9 11.9 21.9 36.7 6.5 7.9 8.7 8.8 9.1 volume 5 kg 1133 (10 min) flow rate (MVR) ESC in rapeseed oil Time 2.4% edge ISO h 23 23 7 1 0.1 20 20 20 20 20 until fibre 4599 fracture elongation Heat 50 kW/m.sup.2 ISO kW/m.sup.2 37 44 39 42 59 43 50 58 52 49 release 5660-1 (3 mm) MARHE Smoke 50 kW/m.sup.2 ISO gas without 5659-2 density ignition (3 mm) flame Ds(4) 217 162 140 117 154 248 203 249 247 254 VOF4 min 363 317 227 186 225 415 294 421 469 454 Feedstock 22 23 (% by wt.) 19 20 21 (comp.) (comp.) 24 25 26 27 A-1 64 68.5 70 73 76.5 67.8 68.8 69.8 70.8 B-1 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 C 5 5 5 5 5 5 5 5 5 D 12.5 8 6.5 3.5 0 9.5 9.5 9.5 9.5 E-1 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 F-1 3.8 3.8 3.8 3.8 3.8 3 2 1 0 F-2 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 F-3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 F-4 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Test Condition Standard Unit Izod impact 23° C. ISO kJ/m.sup.2 67 73 106 128 144 59 62 64 64 resistance 180/1 U Tensile 1 mm/min ISO MPa 4729 4582 4037 3627 3302 4463 4429 4311 4320 modulus 527-1, -2 Vicat 50N; ISO ° C. 109 109 111 111 113 111 111 112 112 softening 120° C./h 306 temperature Viscosity function Melt 260° C. ISO Pas 1093 1097 1088 1088 982 1077 1078 1098 1159 viscosity 11443 [100 s − 1] Melt 260° C. ISO Pas 397 391 404 404 382 385 382 391 402 viscosity 11443 [1000 s − 1] Melt 260° C. ISO Pas 306 303 317 317 300 295 291 301 311 viscosity 11443 [1500 s − 1] Melt 260° C.; ISO cm3/ 7.2 7.3 9.3 9.9 10.4 7.4 7.4 7.2 7.6 volume 5 kg 1133 (10 min) flow rate (MVR) ESC in rapeseed oil Time 2.4% edge ISO h 23 23 41 23 7 26 31 39 23 until fibre 4599 fracture elongation Heat 50 kW/m.sup.2 ISO kW/m.sup.2 53 54 54 76 81 31 36 37 35 release 5660-1 (3 mm) MARHE Smoke 50 kW/m.sup.2 ISO gas without 5659-2 density ignition (3 mm) flame Ds(4) 224 254 249 287 361 217 168 228 190 VOF4 min 364 408 432 482 578 355 318 412 376 Feedstock (% by wt.) 28 29 30 31 32 33 34 35 A-1 64 65.5 68.5 70 68 70.2 55.4 71.3 B-1 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 C 5 5 5 5 5 5 5 5 D 9.5 9.5 9.5 9.5 9.5 9.5 9.5 9.5 E-1 12.5 11 8 6.5 E-2 9.5 6.3 E-3 21.1 5.2 F-1 3.8 3.8 3.8 3.8 3.8 3.8 3.8 3.8 F-2 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 F-3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 F-4 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Test Condition Standard Unit Izod impact 23° C. ISO kJ/m.sup.2 41 52 84 96 108 124 36 117 resistance 180/1 U Tensile 1 mm/min ISO MPa 4688 4435 4147 4085 4198 4145 4662 4116 modulus 527-1, -2 Vicat 50N; ISO ° C. 100 105 114 120 118 126 145 146 softening 120° C./h 306 temperature Viscosity function Melt 260° C. ISO Pas 811 911 1284 1503 1220 1559 2324 2708 viscosity 11443 [100 s − 1] Melt 260° C. ISO Pas 308 342 449 503 413 464 674 775 viscosity 11443 [1000 s − 1] Melt 260° C. ISO Pas 243 267 345 376 315 355 515 581 viscosity 11443 [1500 s − 1] Melt 260° C.; ISO cm3/ 11.2 9.3 6.2 5.1 6.5 4.0 2.8 2.5 volume 5 kg 1133 (10 min) flow rate (MVR) ESC in rapeseed oil Time 2.4% edge ISO h 21 21 21 21 35 37 25 24 until fibre 4599 fracture elongation Heat 50 kW/m.sup.2 ISO kW/m.sup.2 44 43 45 42 68 36 82 61 release 5660-1 (3 mm) MARHE Smoke 50 kW/m.sup.2 ISO gas without 5659-2 density ignition (3 mm) flame Ds(4) min 208 208 198 202 243 153 235 161 VOF4 min 343 359 331 348 411 287 416 256