POLYCARBONATE COMPOSITIONS CONTAINING POLYETHYLENE WAX

Abstract

The invention relates to polycarbonate compositions with an improved thermal behaviour and improved slip characteristics, achieved by the use of oxidised, acid-modified polyethylene waxes.

Claims

1.-13. (canceled)

14. A polycarbonate composition comprising A) polycarbonate B) oxidized acid-modified polyethylene wax and D) an inorganic filler, wherein the oxidized acid-modified polyethylene wax has an acid number of <10 mg KOH/g, a crystallinity of greater than 60% and less than 90%, a melting point between 90° C. and 130° C. and a viscosity average molar mass between 1500 g/mol and 5000 g/mol.

15. The composition as claimed in claim 14, wherein the composition comprises 20.0 to 99.8 wt % of polycarbonate.

16. The composition as claimed in claim 14, wherein the composition comprises 0.05 to 10.0 wt % of oxidized acid-modified polyethylene wax.

17. The composition as claimed in claim 14, wherein the composition comprises 0.2 to 0.5 wt % of oxidized acid-modified polyethylene wax.

18. The composition as claimed in claim 14, wherein the composition comprises 0.04 to 4.0 wt % of additives selected from the group consisting of heat stabilizers, demolding agents and UV stabilizers.

19. The composition as claimed in claim 14, wherein the composition comprises flame retardants and/or colorants.

20. The composition as claimed in claim 14, wherein the inorganic filler is a glass fiber.

21. The composition as claimed in claim 14, wherein the composition comprises 0.002 to 0.2 wt % of heat stabilizer, 0.01 wt % to 1.00 wt % of UV stabilizer and 0.05 wt % to 2.00 wt % of demolding agent.

22. The composition as claimed in claim 14, wherein the oxidation index of the oxidized acid-modified polyethylene wax is greater than 8.

23. The composition as claimed in claim 14, wherein the oxidized acid-modified polyethylene wax has a melt viscosity, determined as per ISO 11443, between 70 mPa.Math.s and 800 mPa.Math.s.

24. The composition as claimed in claim 14, wherein it consists of A) 46.0 to 99.8 wt % of polycarbonate, B) 0.05 to 10 wt % of oxidized acid-modified polyethylene wax, C1) 0.04 to 4.0 wt % of additives selected from the group of heat stabilizers, demolding agents and/or UV stabilizers, C2) optionally further additives selected from the group of flame retardants, colorants, antistats and/or impact modifiers and D) 5.0 to 30.0 wt % of inorganic fillers.

25. A molding produced from a composition as claimed in claim 14.

26. A method comprising utilizing oxidized acid-modified polyethylene waxes for reducing the coefficients of dynamic and static friction and/or improving the ball indentation temperature of polycarbonate compositions filled with at least one inorganic filler.

Description

EXAMPLES

[0130] Raw materials used: [0131] PC-1: Heat-stabilized bisphenol A polycarbonate having a melt volume flow rate MVR of 12.5 cm.sup.3/10 min at 300° C./1.2 kg, Covestro Deutschland AG (previously Bayer MaterialScience AG, Leverkusen); [0132] PC-2: Polycarbonate powder based on Makrolon 3108 (Bisphenol A polycarbonate having a melt volume flow rate MVR of 6 cm.sup.3/10 min at 300° C./1.2 kg, Covestro Deutschland AG (previously Bayer MaterialScience AG, Leverkusen)); [0133] PC-3: Heat-stabilized BPA polycarbonate having a melt volume flow rate MVR of 9.5 cm.sup.3/10 min at 300° C./1.2 kg, Covestro Deutschland AG (previously Bayer MaterialScience AG, Leverkusen); [0134] PC-4: Heat-stabilized BPA polycarbonate having a melt volume flow rate MVR of 6 cm.sup.3/10 min at 300° C./1.2 kg, Covestro Deutschland AG (previously Bayer MaterialScience AG, Leverkusen); [0135] TOF Triisooctyl phosphate, Lanxess AG, Leverkusen; [0136] PETS: Pentaerythritol tetrastearate: Loxiol VPG 861, Emery Oleochemicals; [0137] Tin 329: Tinuvin 329; hydroxybenzotriazole, UV absorber, BASF SE, Ludwigshafen; [0138] Glass fiber: Chopped Strands CS 7942 glass fiber, fiber diameter 14 μm, fiber length 4.5 mm, Lanxess AG, Leverkusen; [0139] PE wax: Oxidized acid-modified polyethylene wax having a molecular weight of 4000 g/mol, an acid number of 1 mg KOH/g, a degree of crystallinity of 80% and a melting point (DSC) of 121° C. and also a melt viscosity (at 140° C.) of 650 mPa*s. Hi-Wax 405MP from Mitsui Chemicals Inc. was used. The oxidation index (determined according to the method described above) is 9. [0140] C4 salt: Potassium perfluorobutanesulfonate; Lanxess AG, Leverkusen [0141] Comparative waxes: Oxidized acid-modified polyethylene wax (I) having a molecular weight of 2600 g/mol, an acid number of 17 mg KOH/g, a degree of crystallinity of 62% and a melting point (DSC) of 100° C. and also a melt viscosity (at 140° C.) of 300 mPa*s, Hi-Wax 4202E from Mitsui. Chemicals Inc. was used. The oxidation index (determined according to the method described above) is 481. [0142] Acid-modified polyethylene wax (II) having a molecular weight of 1500 g/mol, an acid number of 60 mg KOH/g, a degree of crystallinity of 60% and a melting point (DSC) of 104° C. and also a melt viscosity (at 140° C.) of 150 mPa*s. Hi-Wax 1105A from Mitsui Chemicals Inc, was used. The oxidation index (determined according to the method described above) is 1057.

[0143] Melt viscosity was determined as per ISO 11443 with a Göttfert Visco-Robo 45.00 instrument.

[0144] Melt volume flow rate MVR was determined in accordance with ISO 1133 at a test temperature of 300° C. and loading of 1.2 kg using a Zwick 4106 instrument from Zwick Roell. The abbreviation MVR stands for the starting melt volume flow rate (after 5 minutes preheating time) and the abbreviation IMVR20′ stands for melt volume flow rate after 20 min.

[0145] The Vicat softening temperature VST/B50 as a measure of heat distortion resistance was determined in accordance with ISO 306 on test specimens measuring (80×10×4) mm with a 50 N ram loading and a heating rate of 50° C./h with a Coesfeld Eco 2920 instrument from Coesfeld Materialtest.

[0146] The heat deflection temperature (HDT) as a measure of distortion temperature was measured according to DIN EN ISO 75 on test specimens having the dimensions (80×10×4) mm with a loading of 1.8 MPa (HDT A) or 0.45 MPa (HDT B) with a HDT Vollautomat instrument from Coesfeld.

[0147] Heat resistance (ball indentation test, BIT) was measured according to IEC 60335-1 on test specimens having the dimensions (127×12.7×3) mm.

[0148] The coefficients of friction were determined using a modified Arburg-370S-800-150 injection molding machine. The method is described in EP 1 377 812 B1. Comparative examples 1 to 3 and 6 to 7 are used as an internal standard.

[0149] The fire behavior was measured according to UL94 Von bars having the dimensions (127×12.7×1.5) mm.

TABLE-US-00001 TABLE 1 Performed experiments 1 to 9 1 2 3 4 5 6 7 8 9 (comp.) (comp.) (comp.) (comp.) (comp.) (comp) (comp.) (comp.) (comp.) Formulation: PC-1 wt % 85.0 85.0 85.0 85.0 85.0 85.0 85.0 85.0 85.0 PC-2 wt % 15.0 14.8 14.6 14.8 14.6 14.8 14.6 14.8 14.6 PETS wt % — 0.2 0.4 — — — — — — oxid. acid-mod. PE wax wt % — — — 0.2 0.4 — — — — comparative wax (I) wt % — — — — — 0.2 0.4 — — comparative (II) wt % — — — — — — — 0.2 0.4 Tests: MVR cm.sup.3/10 min 9.7 9.8 10.1 9.6 9.9 11.3 12.1 11.4 11.3 IMVR20′ cm.sup.3/10 min 9.6 9.9 10.4 9.7 9.8 11.3 12.8 11.9 11.9 delta MVR/IMVR20′ −0.1 0.1 0.3 0.1 −0.1 0.0 0.7 0.5 0.6 vicat VST/B/50 ° C. 146.8 145.6 144.0 146.3 145.5 145.9 145.4 145.5 145.2 Coefficients of friction static friction 0.60 0.35 0.32 0.25 0.23 dynamic friction 0.51 0.33 0.30 0.23 0.21

[0150] Examples 1 to 9 are comparative examples. It is apparent that the polycarbonate compositions of examples 4 and 5 comprising the oxidized acid-modified polyethylene wax have higher Vicat temperatures than compositions comprising the same amount of the conventional demolding agent PETS or comprising comparative waxes having higher acid numbers while also exhibiting reduced coefficients of static and dynamic friction. The compositions 4 and 5 accordingly have improved thermal properties while also being easier to process on account of the low friction.

[0151] It is furthermore a feature of examples 4 and 5 that test specimens ((155×75×2.3) mm sheets) produced from the polycarbonate compositions attract markedly less dust in a dust atmosphere (coal dust). This is advantageous for injection molded parts in use.

TABLE-US-00002 TABLE 2 Performed experiments 10 to 17 10 11 14 15 16 17 (comp.) (comp.) 12 13 (comp.) (comp.) (comp.) (comp.) Raw materials PC-3 wt % 79.1 79.09 79.19 79.09 79.19 79.09 79.19 79.09 PC-4 wt % 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 GF CS 7942 wt % 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 PETS wt % 0.45 0.45 — — — — — — oxid. acid-mod. PE wt % — — 0.35 0.45 — — — — wax TIN 329 wt % 0.25 0.25 0.25 0.25 0.25 0.25 0.23 0.25 C4 salt wt % 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 TOF wt % — 0.01 0.01 0.01 0.01 0.01 0.01 0.01 comparative wax (I) wt % — — — — 0.35 0.45 — — comparative wax (II) wt % — — — — — — 0.35 0.45 Tests: MVR ml/10 10.0 6.4 6.3 6.0 7.2 7.5 6.5 6.5 min IMVP20′ ml/10 11.8 7.2 7.1 6.9 8.5 8.5 7.2 7.2 min delta MVR/IMVR20′ 1.8 0.8 0.8 0.9 1.3 1.0 0.7 0.7 Vicat VST/B/50 ° C. 144.5 144.7 147.1 147.2 45.6 144.6 143.1 142.7 HDT A ° C. 134.7 135.2 138.3 137.8 136.6 137.1 133.1 131.9 HDT B ° C. 141.7 141.6 144.8 144.9 143.3 143.5 141.4 140.6 BIT ° C. 136 115 138 138 136 136 136 135 Mechanics ISO180/1U impact kJ/m.sup.2 58 50 41 42 — — strength brittle brittle brittle brittle UL94V (1.5 mm) overall assessment s V2 V0 V1 V0 — — Coefficient of friction static friction 0.30 0.25 0.18 0.19 — — dynamic friction 0.28 0.23 0.17 0.18 — —

[0152] Examples 10 and 11 and 14 and 17 are comparative examples while examples 12 and 13 are according to the invention. It is apparent that the polycarbonate compositions according to the invention of examples 12 and 13 comprising the oxidized acid-modified polyethylene wax have higher Vicat temperatures, higher heat distortion temperatures (HDT) and improved ball indentation temperatures (BIT) while also exhibiting reduced coefficients of static and dynamic friction than corresponding compositions comprising the conventional demolding agent PETS or comprising comparative waxes having a higher acid number. Particularly for smart meter applications, ball indentation temperatures of 134° C. to 136° C., as are achieved with comparable amounts of PETS in the polycarbonate compositions, are too low. The effect achieved by employment of the oxidized acid-modified polyethylene waxes is particularly noticeable in example 12 in which the content of oxidized acid-modified polyethylene wax was even reduced compared to the PETS of comparative example 11.

[0153] Compared to comparative examples 14 and 17, it is apparent that the reduction in the acid number of the oxidized acid-modified polyethylene wax results in better thermal properties while also resulting in better melt stability. Vicat temperatures and BIT at least about 2° C. above the values obtained using higher acid numbers in the polyethylene wax were achieved in accordance with the invention. In addition the compositions according to the invention also result in a lower delta MVR/IMVR20′ than when the comparative wax (I) is used which demonstrates that a better melt stability is present than when a comparable wax having a higher acid number is used.

[0154] The polycarbonate compositions according to the invention thus have improved thermal properties while also being easier to process on account of the low friction.