MINERAL-FILLED POLYCARBONATE-POLYALKYLENE TEREPHTHALATE COMPOSITION, MOULDING COMPOUND AND MOULDED BODIES WITH GOOD IMPACT TOUGHNESS

Abstract

The invention relates to a composition for producing a thermoplastic moulding compound, wherein the composition contains the following constituents or consists of same: A) between 50 and 70 wt. % of at least one aromatic polycarbonate, B) between 16 and 40 wt. % of at least one polyalkylene terephthalate, C) between 8 and 22 wt. % of at least one mineral filler based on talc, D) between 0.0110 and 0.0280 wt. % of phosphorous acid, and E) between 0 and 8.0 wt. % of at least one additive. Furthermore, the invention relates to a method for producing a thermoplastic moulding compound from the composition, to the moulding compound itself, and to the use of the composition and the moulding compound for producing moulding bodies.

Claims

1. A thermoplastic molding composition comprising: A) 50% to 70% by weight of at least one aromatic polycarbonate, B) 16% to 40% by weight of at least one polyalkylene terephthalate, C) 8% to 22% by weight of at least one talc-based mineral filler, D) 0.0110% to 0.0280% by weight of phosphorous acid, E) 0% to 8.0% by weight of at least one additive.

2. The composition of claim 1, wherein component A has a weight-average molecular weight Mw, determined by gel permeation chromatography in methylene chloride using polycarbonate based on bisphenol A as a standard, of 22 to 28 kg/mol.

3. The composition of claim 1, wherein component B is selected from the group consisting of polyethylene terephthalates and polybutylene terephthalates.

4. The composition of claim 3, wherein component B is a polyethylene terephthalate having an intrinsic viscosity of 0.58 dl/g to 0.68 dl/g is employed as component B.

5. The composition of claim 1, wherein component C is a talc having an Al.sub.2O.sub.3 content of less than 0.7% by weight.

6. The composition of claim 1, wherein component C has an upper grain size d.sub.95 of less than 6 μm.

7. The composition of claim 1, wherein component D is solid.

8. The composition of claim 1, wherein the weight ratio of component D to component B is 0.0003:1 to 0.0010:1.

9. The composition of claim 1, wherein the composition does not comprise any fillers or reinforcers other than component C.

10. The composition of claim 1 comprising: 54% to 66% by weight of component A, 20% to 26% by weight of component B, 12% to 18% by weight of component C, 0.0120% to 0.0220% by weight of the component D, 0.3% to 6% by weight of component E.

11. The composition of claim 1 consisting of components A to E.

12. A process for producing a molding compound, wherein the constituents of the composition of claim 1 are mixed with one another at a temperature of 200° C. to 320° C. and subsequently cooled and pelletized.

13. A molding compound produced by the process of claim 12.

14. (canceled)

15. A molded article produced from the composition of claim 1.

16. A molded article produced from the molding compound of claim 13.

Description

EXAMPLES

[0182] Component A

[0183] Linear polycarbonate based on bisphenol A having a molecular weight of 24 kg/mol (weight-average M.sub.w, measured by GPC (gel permeation chromatography) using a polycarbonate standard based on bisphenol A).

[0184] Component B

[0185] Polyethylene terephthalate (for example PET from Invista, Germany) having an intrinsic viscosity of 0.623 dl/g. The specific viscosity is measured in dichloroacetic acid in a concentration of 1% by weight at 25° C. The intrinsic viscosity is calculated from the specific viscosity according to the following formula.

Intrinsic viscosity=specific viscosity×0.0006907+0.063096

[0186] Component C

[0187] Talc having an average particle diameter d.sub.50 of 1.2 μm and a d.sub.95 of 3.5 m measured using a sedigraph and having an Al.sub.2O.sub.3 content of 0.5% by weight.

[0188] Component D

[0189] Phosphorous acid H.sub.3PO.sub.3 as a solid

[0190] Component E-1

[0191] Black Pearls™ 800 carbon black

[0192] Component E-2

[0193] Montanic acid ester wax (Licowax™ E) as a lubricant/demolding agent

[0194] Component E-3

[0195] Pentaerythritol tetrastearate as a lubricant/demolding agent

[0196] Production of the Molding Compounds

[0197] The molding compounds according to the invention containing the components A to E are produced on a ZSK25 twin-screw extruder from Coperion, Werner and Pfleiderer (Germany) at melt temperatures of 270° C. to 290° C.

[0198] Production of the Test Specimens and Testing

[0199] The pellets obtained from the respective compounding were processed into test specimens on an injection molding machine (for example from Arburg) at a melt temperature of 270° C. and a mold temperature of 70° C.

[0200] Melt flowability is assessed by means of the melt volume flow rate (MVR) measured according to ISO 1133 (2012 version) at a temperature of 270° C. and with a die load of 5 kg.

[0201] Heat resistance was measured according to DIN ISO 306 (Vicat softening temperature, method B with 50 N load and a heating rate of 120 K/h, 2013 version) on a test specimen injection-molded from one side and having dimensions of 80×10×4 mm.

[0202] Impact strength is determined according to ISO 180/1U (1982 version) at room temperature (23° C.) or −30° C. by a 10-fold determination on test bars measuring 80 mm×10 mm×4 mm.

[0203] The examples which follow serve to further elucidate the invention.

TABLE-US-00001 TABLE 1 Component (parts by weight) V1 2 3 4 V5 A PC 61.4 61.4 61.4 61.4 61.4 B PET 22.6 22.6 22.6 22.6 22.6 C Talc 15.0 15.0 15.0 15.0 15.0 D H3PO3 0.0100 0.0125 0.0150 0.0200 0.0300 E-1 Carbon black 0.45 0.45 0.45 0.45 0.45 E-21 Licowax 0.2 0.2 0.2 0.2 0.2 E-3 PETS 0.37 0.37 0.37 0.37 0.37 Properties Unit Vicat °C. 143 142 143 143 143 MVR cm.sup.3/10 min 34 35 33 34 37 Izod impact strength 23° C. kJ/m.sup.2 64 89 85 74 65 Izod impact strength −30° C. kJ/m.sup.2 67 69 71 70 64

[0204] Table 1 shows that the compositions according to the invention allow production of molding compounds having good flowability (MVR) and molded articles having a high heat resistance (Vicat) in conjunction with improved impact strength at room temperature and at −30° C. If the concentration of component D is outside the claimed range the impact strength is insufficient. The compositions according to examples 2 and 3 for which the impact strength at 23° C. is most improved are very particularly preferred.