SiCoPC blend containing phosphazene and silicone/acrylate impact modifier

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) 42% to 80% by weight of at least one polymer selected from the group consisting of aromatic polycarbonate and aromatic polyestercarbonate, B) 2% to 38% by weight of at least one polysiloxane-polycarbonate block co-condensate, C) 1% to 15% by weight of at least one rubber-modified graft polymer comprising C.1) 5% to 95% by weight based on the graft polymer C of a shell composed of at least one vinyl monomer and C.2) 95% to 5% by weight based on the graft polymer C of a graft substrate composed of silicone-acrylate composite rubber, D) 2% to 10% by weight of at least one phosphazene, E) 0% to 10% by weight of at least one additive, to the moulding compound itself, to the use of the composition or moulding compound for production of moulded articles and to the moulded articles themselves.

Claims

1. Composition for producing a thermoplastic moulding compound, wherein the composition contains: A) 42% to 80% by weight of at least one polymer selected from the group consisting of aromatic polycarbonate and aromatic polyestercarbonate, B) 2% to 38% by weight of at least one polysiloxane-polycarbonate block co-condensate characterized in that component B contains siloxane blocks derived from one of the following structures: ##STR00024## wherein R1 represents hydrogen, Cl, Br, C1-C4-alkyl, R2 independently represents aryl or alkyl, X represents a single bond, C1 to C5-alkylene, C2 to C5-alkylidene, C5 to C12-cycloalkylidene, —O—, —SO— —CO—, —S—, or —SO2—, n is a number between 10 and 150 determined by 1H-NMR spectroscopy, m is a number from 1.5 to 5 determined by 1H-NMR spectroscopy, C) 1% to 15% by weight of at least one rubber-modified graft polymer comprising C.1) 5% to 95% by weight based on the graft polymer C of a shell composed of at least one vinyl monomer and C.2) 95% to 5% by weight based on the graft polymer C of a graft substrate composed of silicone-acrylate composite rubber, D) 2% to 10% by weight of at least one phosphazene, E) 0% to 10% by weight of at least one additive.

2. Composition according to claim 1, characterized in that the graft substrate C.2 contains 20% to 80% by weight of silicone rubber and 80% to 20% by weight of polyalkyl (meth)acrylate rubber.

3. Composition according to claim 1, characterized in that the component B contains a proportion of 2% to 20% by weight of siloxane blocks.

4. Composition according to claim 1, characterized in that component C.1 is methyl methacrylate.

5. Composition according to claim 1, characterized in that component E contains talc.

6. Composition according to claim 1 containing: 50% to 70% by weight of component A, 15% to 35% by weight of component B, 5% to 11% by weight of component C, 4% to 8% by weight of component D, 0.2% to 5% by weight of component E.

7. Composition according to claim 1 consisting of components A, B, C, D and E.

8. Moulded article obtained from the composition according to claim 1.

Description

EXAMPLES

(1) Component A:

(2) Bisphenol A-based linear polycarbonate having a weight-averaged molecular weight M.sub.w of 26 500 g/mol (determined by GPC in methylene chloride using a bisphenol A-based polycarbonate as a standard).

(3) Component B:

(4) Polysiloxane-polycarbonate block co-condensate composed of bisphenol A and siloxane blocks of structure (13)

(5) ##STR00022##
having an MVR of about 4 (measured at 300° C., 1.2 kg; ISO 1133) and a siloxane block content of about 5% by weight (where n=30 and m=3-4; R1=H; R2=methyl).

(6) Component C-1

(7) Graft polymer composed of 14% by weight of methyl methacrylate on 86% by weight of a silicone-acrylate composite rubber as the graft substrate, wherein the silicone-acrylate composite rubber contains 36% by weight of silicone rubber and 64% by weight of polyalkyl (meth)acrylate rubber and wherein the two recited rubber components penetrate one another in the composite rubber and are therefore essentially inseparable.

(8) Component C-2

(9) Graft polymer composed of 17% by weight of methyl methacrylate on 83% by weight of a silicone-acrylate composite rubber as the graft substrate, wherein the silicone-acrylate composite rubber contains 11% by weight of silicone rubber and 89% by weight of polyalkyl (meth)acrylate rubber and wherein the two recited rubber components penetrate one another in the composite rubber and are therefore essentially inseparable.

(10) Component C-3

(11) Graft polymer produced by reaction of 11% by weight of methyl methacrylate on 89% by weight of a silicone-acrylate composite rubber as the graft substrate, wherein the silicone-acrylate composite rubber contains 92% by weight of silicone rubber and 8% by weight of polyalkyl (meth)acrylate rubber and wherein the two recited rubber components penetrate one another in the composite rubber and are therefore essentially inseparable.

(12) Component C-4

(13) Graft polymer of MBS type in which 15% by weight of a shell of methyl methacrylate are grafted onto 85% by weight of a polybutadiene-styrene rubber substrate, EXL 2650A, Dow Chemical.

(14) Component D:

(15) Phenoxyphosphazene of formula (16) having a proportion of oligomers where k=1 of 70 mol %, a proportion of oligomers where k=2 of 18 mol % and a proportion of oligomers where k>3 of 12 mol %.

(16) ##STR00023##

(17) Component E-1:

(18) Compacted talc having a talc content of 99%, an iron oxide content of 0.4%, an aluminium oxide content of 0.4%, ignition loss of 6.0%, pH (to EN ISO 787-9:1995) of 9.55, D50 (sedimentation analysis) of 0.65 μm; BET surface area 13.5 m2/g, type: HTPultra5c, manufacturer: Imifabi

(19) Component E-2:

(20) Cycolac INP449: polytetrafluoroethylene (PTFE) preparation from Sabic composed of 50% by weight of PTFE contained in an SAN copolymer matrix.

(21) Component E-3:

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

(23) Component E-4:

(24) Pentaerythritol tetrastearate (demoulding agent)

(25) Component E-5:

(26) Black Pearls™ 800 (Cabot Corp., Belgium): carbon black pigment

(27) Production and Testing of the Moulding Compounds According to the Invention

(28) The components were mixed in a ZSK-25 twin-screw extruder from Werner & Pfleiderer 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.

(29) Employed as a measure for hydrolysis resistance is the percentage change in MVR at 260° C. (according to ISO 1133, 2012 version, with an applied load of 5 kg) during storage of the granulate at 95° C. and 100% relative humidity for 7 days.

(30) Elastic modulus is determined at room temperature according to ISO 527 (1996 version).

(31) The IZOD notched impact strength was determined at −20° C. on test bars having dimensions of 80 mm×10 mm×4 mm according to ISO 180/U (2013 version).

(32) Maximum force in the puncture test according to ISO 6603-2 (2002 version) is used as a measure for material ductility under multiaxial stress. This is performed at 23° C. on test specimens having dimensions of 60 mm×60 mm×2 mm.

(33) Flame retardancy is assessed on strips measuring 127×12.7×1.5 mm in accordance with UL94V.

(34) Stress cracking (ESC) resistance in rapeseed oil at room temperature was used as a measure for 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).

(35) To assess surface quality a specimen sheet having dimensions of 60×40×2 mm is produced at an injection-moulding temperature of 290° C. and subsequently visually inspected. A glossy homogenous surface of the injection-moulded article is designated “$” and in case of small marks is designated “*”. If the sheets are matt this is noted accordingly.

(36) All moulding compounds from the tables 1 to 3 achieve a UL 94 V rating of at least V1 at 1.5 mm.

(37) TABLE-US-00001 TABLE 1 Moulding compounds and properties thereof (Comp.) (Comp.) 1 2 3 4 5 Components [parts by weight] A 83.2 73.2 63.2 53.2 43.2 B 10.0 20.0 30.0 40.0 C-1 9.0 9.0 9.0 9.0 9.0 D 6.5 6.5 6.5 6.5 6.5 E-2 0.8 0.8 0.8 0.8 0.8 E-3 0.1 0.1 0.1 0.1 0.1 E-4 0.4 0.4 0.4 0.4 0.4 E-5 0.5 0.5 0.5 0.5 0.5 Properties IZOD notched impact 47.9 46.3 50.2 52.4 52.4 strength at −20° C. [kJ/m.sup.2] Delta hydrolysis 64% 63% 61% 52% 78% Stress cracking (ESC) 12:25 14:20 15:35 24:05 38:35 resistance [h:min until fracture] Elastic modulus [N/mm.sup.2] 2028 1995 1998 1980 1970 Max. puncture force [N] 4548 4519 4505 4440 4391 Surface assessment MPL/ $ $ $ $ $ appearance $ . . . glossy; * . . . small mark; matt

(38) TABLE-US-00002 TABLE 2 Moulding compounds and properties thereof (Comp.) (Comp.) 6 7 8 9 10 Components [parts by weight] A 80.2 70.2 60.2 50.2 40.2 B 10.0 20.0 30.0 40.0 C-1 9.0 9.0 9.0 9.0 9.0 D 6.5 6.5 6.5 6.5 6.5 E-1 3.0 3.0 3.0 3.0 3.0 E-2 0.8 0.8 0.8 0.8 0.8 E-3 0.1 0.1 0.1 0.1 0.1 E-4 0.4 0.4 0.4 0.4 0.4 E-5 0.5 0.5 0.5 0.5 0.5 Properties IZOD notched impact 22.8 41.6 50.6 52.7 56.0 strength at −20° C. (brittle) (tough) (tough) (tough) (tough) [kJ/m.sup.2] Delta hydrolysis 42% 42% 43% 38% 45% Stress cracking (ESC) 17:30 21:01 40:16 57:55 71:55 resistance [h:min until fracture] Elastic modulus [N/mm.sup.2] 2314 2267 2247 2212 2180 Max. puncture force [N] 4364 4371 4292 4356 3881 Surface assessment MPL/ $ $ $/* $/* $/* appearance $ . . . glossy; * . . . small mark; matt

(39) TABLE-US-00003 TABLE 3 Moulding compounds and properties thereof 3 11 4 12 Components [parts by weight] A 63.2 63.2 53.2 53.2 B 20.0 20.0 30.0 30.0 C-1 9.0 9.0 C-2 9.0 C-3 9.0 D 6.5 6.5 6.5 6.5 E-2 0.8 0.8 0.8 0.8 E-3 0.1 0.1 0.1 0.1 E-4 0.4 0.4 0.4 0.4 E-5 0.5 0.5 0.5 0.5 Properties IZOD notched impact strength 50.2 48.6 52.4 46.6 at −20° C. [kJ/m.sup.2] Delta hydrolysis 61% >200% 52% 195% Stress cracking (ESC) resistance 15:35 13:15 24:05 16:00 [h:min until fracture] Elastic modulus [N/mm.sup.2] 1998 1977 1980 1964 Max. puncture force [N] 4505 4501 4440 4213 Surface assessment MPL/ $ somewhat $ matt appearance $ . . . glossy; matt * . . . small mark n.m.: not measurable, too high

(40) TABLE-US-00004 TABLE 4 Moulding materials and properties thereof 13 14 15 16 Components [parts by weight] A 67.2 67.2 51.2 51.2 B 20.0 20.0 30.0 30.0 C-1 5.0 11.0 C-4 5.0 11.0 D 6.0 6.0 6.0 6.0 E-2 0.8 0.8 0.8 0.8 E-3 0.1 0.1 0.1 0.1 E-4 0.9 0.9 0.9 0.9 Properties IZOD notched impact strength 52 54 50 48 at −20° C. [kJ/m.sup.2] Delta hydrolysis 46 48 44 59 Stress cracking (ESC) resistance 16:20 14:00 20:35 14:30 [h:min until fracture] Elastic modulus [N/mm.sup.2] 2176 2192 1904 1983 Max. puncture force [N] 4725 4714 4273 4322 Surface assessment MPL/ $ $ $/* $ appearance $ . . . glossy; * . . . small mark

(41) The examples from tables 1-4 show that the compositions and the moulded articles according to the invention exhibit a good balance of good low temperature notched impact strength, high maximum force in the puncture test (i.e. good multiaxial toughness), high stiffness, good stability toward hydrolytically induced molecular weight degradation (low MVR increase) and high chemicals resistance.

(42) Notched impact strength and chemicals resistance are poorer without the component B (comp. 1).

(43) If the proportion of the component B is excessively high surface quality may deteriorate somewhat (table 2), hydrolysis resistance is reduced, as are toughness in the puncture test and stiffness.

(44) The compositions of the examples comprising 20% and 30% by weight of the component B, in which the advantages of the use of component B in terms of toughness and chemicals resistance are most marked without stiffness and toughness in the puncture test having already deteriorated significantly, are particularly advantageous.

(45) The use of component C-1 is likewise preferred. This graft polymer results in a particularly good chemicals resistance, notched impact strength at low temperatures and a high stability toward thermally induced molecular weight degradation and a good moulded article surface (table 3).

(46) The data in table 4 finally show that the graft polymer according to the invention makes it possible to achieve an altogether advantageous profile of properties compared to an MBS graft polymer. Especially hydrolysis stability and chemicals resistance are improved over MBS through the use of the graft polymer according to the invention while the other properties investigated are at a similar level.