POLYCARBONATE COMPOSITIONS WITH IMPROVED STABILISATION

Abstract

The invention relates to compositions containing A) at least one polymer selected from the group of aromatic polycarbonates and aromatic polyester carbonates and B) at least one Brnsted-acidic compound selected from the group consisting of compounds of general formulae (I) and (II)

(R1).sub.y1-N[R2-COOH].sub.x1(I)

[HOOCR2].sub.x2(R1).sub.y2N(R3)-N(R1).sub.y3[R2-COOH].sub.x3(II) wherein R1 represents optionally functionalized or heteroatom-substituted alkyl, aryl or cycloalkyl, R2 represents C.sub.1- to C.sub.8-alkylene or C.sub.2- to C.sub.8-alkylidene, R3 represents (CH.sub.2).sub.n, (CH.sub.2).sub.n[O(CH.sub.2).sub.n].sub.m or (CH.sub.2).sub.n[NR4(CH.sub.2).sub.n].sub.m, n is an integer, m is an integer, R4 represents optionally functionalized or heteroatom-substituted alkyl, aryl or cycloalkyl, x1 is an integer between 1 and 3, x2 and x3 are respectively 1 or 2, and y1 is given by the formula y1=3x1, y2 by the formula y2=2x2, y3 by the formula y3=2x3, and wherein in compounds having a plurality of radicals R1 and/or R2 these may independently of one another represent different or identical radicals having the abovementioned definitions, and also to a process for producing compositions using components A, B and optionally further components, wherein at least one of the employed components is alkaline or contains alkaline constituents, to compositions obtained by this process and to the use of the compositions for producing molded articles and to the molded articles themselves.

Claims

1.-15. (canceled)

16. A composition containing A) at least one polymer selected from the group of aromatic polycarbonates and aromatic polyester carbonates and B) at least one Brnsted-acidic compound selected from the group consisting of compounds of general formulae (I) and (II)
(R1).sub.y1-N[R2-COOH].sub.x1(I)
[HOOCR2].sub.x2(R1).sub.y2N(R3)-N(R1).sub.y3[R2-COOH].sub.x3(II) wherein R1 represents optionally functionalized or heteroatom-substituted alkyl, aryl or cycloalkyl, R2 represents C.sub.1- to C.sub.8-alkylene or C.sub.2- to C.sub.8-alkylidene, R3 represents (CH.sub.2).sub.n, (CH.sub.2).sub.n[O(CH.sub.2).sub.n].sub.m or (CH.sub.2).sub.n[NR4(CH.sub.2).sub.n].sub.m n is an integer, m is an integer, R4 represents optionally functionalized or heteroatom-substituted alkyl, aryl or cycloalkyl, preferably cycloalkyl, x1 is an integer between 1 and 3, x2 and x3 are respectively 1 or 2, and y1 is given by the formula y1=3x1, y2 by the formula y2=2x2, y3 by the formula y3=2x3, wherein in compounds having a plurality of radicals R1 and/or R2 these may independently of one another represent different or identical radicals having the abovementioned definitions.

17. The composition as claimed in claim 16, wherein component B is selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), nitriloacetic acid, ethylene glycol bis(aminoethylether)-N,N,N,N-tetraacetic acid (EGTA) and diethylenetriaminepentaacetic acid (DTPA).

18. The composition as claimed in claim 16, wherein as component B ethylenediaminetetraacetic acid (EDTA) is employed.

19. The composition as claimed in claim 16, wherein component B is present in the composition in a proportion of 0.00001% to 0.5% by weight.

20. The composition as claimed in claim 16, wherein furthermore as component C one or more rubber-containing graft polymers and/or rubber-free vinyl (co)polymers are present.

21. The composition as claimed in claim 20, wherein component C contains at least one rubber-containing graft polymer produced by emulsion polymerization.

22. The composition as claimed in claim 16, wherein at least one alkali metal, alkaline earth metal, aluminum or transition metal salt of a strong mineral acid is present.

23. The composition as claimed in claim 22, wherein the salt is magnesium sulfate.

24. A process for producing thermoplastic polycarbonate compositions containing the steps (i), (ii) and optionally (iii), wherein in a first step (i) A) at least one polymer selected from the group of aromatic polycarbonates and aromatic polyester carbonates and B) at least one Brnsted-acidic compound selected from the group consisting of compounds of general formulae (I) and (II)
(R1).sub.y1-N[R2-COOH].sub.x1(I)
[HOOCR2].sub.x2(R1).sub.y2N(R3)-N(R1).sub.y3[R2-COOH].sub.x3(II) wherein R1 represents an optionally functionalized or heteroatom-substituted alkyl, aryl or cycloalkyl, R2 represents C.sub.1- to C.sub.8-alkylene or C.sub.2- to C.sub.8-alkyidene, R3 represents (CH.sub.2).sub.n, (CH.sub.2).sub.n[O(CH.sub.2).sub.n].sub.m or (CH.sub.2).sub.n[NR4(CH.sub.2).sub.n].sub.m, n is an integer, m is an integer, R4 represents optionally functionalized or heteroatom-substituted alkyl, aryl or cycloalkyl, preferably cycloalkyl, x1 is an integer between 1 and 3, x2 and x3 are respectively 1 or 2, and y1 is given by the formula y1=3x1, y2 by the formula y2=2x2, y3 by the formula y3=2x3, wherein in compounds having a plurality of radicals R1 and/or R2 these may independently of one another represent different or identical radicals having the abovementioned definitions, and optionally further components are heated by supplying thermal and/or mechanical energy to melt at least component A, the components are dispersed in one another and subsequently the resulting composition present in the form of a melt is optionally degassed by applying negative pressure, wherein at least one of the components employed in step (i) is alkaline or contains alkaline constituents and in a further step (ii) the resulting composition is resolidified by cooling and in a further step (iii) is pelletized, wherein these further steps (ii) and (iii) may be performed in any desired sequence.

25. The process as claimed in claim 24, wherein component B is selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), nitriloacetic acid, ethylene glycol bis(aminoethylether)-N,N,N,N-tetraacetic acid (EGTA) and diethylenetriaminepentaacetic acid (DTPA).

26. The process as claimed in claim 24, wherein furthermore as component C at least one rubber-containing graft polymer produced by emulsion polymerization and optionally at least one further component selected from the group consisting of rubber-containing graft polymers produced by bulk, solution or suspension polymerization and rubber-free vinyl (co)polymers is employed and component C contains at least one alkali metal, alkaline earth metal, aluminum or transition metal salt of a strong mineral acid.

27. Use of an acid according to the general formulae (I) or (II)
(R1).sub.y1-N[R2-COOH].sub.x1(I)
[HOOCR2].sub.x2(R1).sub.y2N(R3)-N(R1).sub.y3[R2-COOH].sub.x3(II) wherein R1 represents optionally functionalized or heteroatom-substituted alkyl, aryl or cycloalkyl, R2 represents C.sub.1- to C.sub.8-alkylene or C.sub.2- to C.sub.8-alkylidene, R3 represents (CH2)n, (CH2)n[O(CH2)n]m or (CH2)n[NR4(CH2)n]m, n is an integer, m is an integer, R4 represents optionally functionalized or heteroatom-substituted alkyl, aryl or cycloalkyl, preferably cycloalkyl, x1 is an integer between 1 and 3, x2 and x3 are respectively 1 or 2, and y1 is given by the formula y1=3x1, y2 by the formula y2=2x2, y3 by the formula y3=2x3, and wherein in compounds having a plurality of radicals R1 and/or R2 these may independently of one another represent different or identical radicals having the abovementioned definitions, for stabilizing polycarbonate compositions.

28. A composition produced by a process as claimed in claim 24.

29. Use of compositions as claimed in claim 16 for the production of molded articles.

30. A molded article containing compositions as claimed in claim 16.

Description

EXAMPLES

[0132] Components used:

Component A

[0133] Linear polycarbonate based on bisphenol A having a weight-average molecular weight Mw of 28000 g/mol (determined by gel permeation chromatography (GPC) in a methylene chloride solvent and with a polycarbonate standard).

Component B1

[0134] Trilon BS: Ethylenediaminetetraacetic acid (EDTA); BASF (Ludwigshafen, Germany)

Component B2

[0135] Phenylphosphonic acid (98%), Sigma-Aldrich Chemie GmbH

Component B3

[0136] Citric acid (>99.5%), Merck KGaA

Component B4

[0137] Oxalic acid (?99.0%), Sigma-Aldrich Chemie GmbH

Component B5

[0138] Terephthalic acid (98%), Sigma-Aldrich Chemie GmbH

Component B6

[0139] Phosphorous acid (99%), (Sigma-Aldrich Chemie GmbH).

Component B7

[0140] Fabutit 313: Ca(H.sub.2PO.sub.4).sub.2; Chemische Fabrik Budenheim KG (Budenheim, Germany)

Component B8

[0141] p-toluenesulfonic acid (98%), Alfa Aesar GmbH & Co KG

Component C

[0142] ABS blend having a ratio of acrylonitrile:butadiene:styrene, based on the blend, of 20%:18%:62% by weight, containing an ABS polymer produced in emulsion polymerization, precipitated using magnesium sulfate, worked up in an alkaline medium and containing alkaline constituents and magnesium sulfate, an ABS polymer produced in bulk polymerization, and an SAN polymer.

Component D1

[0143] Pentaerythritol tetrastearate as lubricant/demolding agent

Component D2

[0144] Heat stabilizer, Irganox B900 (mixture of 80% Irgafos 168 (tris(2,4-di-tert-butylphenyl)phosphite) and 20% Irganox 1076 (2,6-di-tert-butyl-4-(octadecanoxycarbonylethyl)phenol); BASF (Ludwigshafen, Germany)

Component D3

[0145] Heat stabilizer, Irganox 1076 (2,6-di-tert-butyl-4-(octadecanoxycarbonylethyl)phenol), BASF (Ludwigshafen, Germany).

Process for Producing Compositions (Molding Materials) from the Employed Components

[0146] In a first process step (i) the components A, B, C and D were mixed at room temperature and the mixture introduced into the intake zone of a ZSK25 twin-screw extruder from Coperion, Werner & Pfleiderer (Stuttgart, Germany) at a flow rate of 20 kg/h. In the melting and kneading zone of the extruder at speeds of 220 and 500 rpm the mixture was brought to temperatures of 260 C. and 290 C. respectively to melt it, and kneaded at this temperature to disperse the components in one another. The thus compounded mixture was degassed in the subsequent degassing zone of the extruder by applying a negative pressure of 100 mbar (absolute) to the melt. In a second process step (ii) the degassed melt was discharged from the extruder at the abovementioned temperatures of 260 C. or 290 C. via a nozzle and the resulting melt strand was passed through a water bath temperature-controlled to about 30 C. for cooling.

[0147] In a third process step (iii) the solidified melt strand was pelletized by means of a strand pelletizer.

Production of the Test Specimens and Testing

[0148] The pelletized materials resulting from the respective compounding were processed in an injection molding machine (from Arburg) at melt temperatures of 260 C. or 300 C. and a mold temperature of 80 C. to afford test specimens having dimensions of 60 mm40 mm2 mm (for determining yellowness indices and gloss levels) and at a melt temperature of 260 C. and a mold temperature of 80 C. to afford test specimens having dimensions of 150 mm105 mm3.2 mm (for determining blistering behavior after storage under hot and humid conditions). Both test specimen types were produced using highly polished injection molds.

[0149] The MVR serves as a measure for any polycarbonate molecular weight degradation during the thermal stress of the compounding and is determined on the pellets produced by compounding after drying at 110 C. for 4 h in a circulating air dryer according to ISO1133 at a melt temperature of 300 C. with a piston loading of 5 kg after a hold time of 5 min.

[0150] The iMVR is determined under the same conditions as the MVR but with a prolonged hold time of 15 min.

Relative increase of iMVR relative to MVR

[0151] MVR(300 C./5 kg, 5 min.fwdarw.15 min)=100%.Math.(iMVRMVR)/MVR serves as a measure for the polycarbonate molecular weight degradation to be expected in the injection mold at elevated processing temperatures and thus as a measure for the processing stability of the composition in the injection mold.

[0152] The natural tone/the inherent color is measured in reflection according to DIN 6174 on specimens having dimensions of 60 mm40 mm2 mm and produced at a melt temperature of 260 C./300 C. in an injection mold. The yellowness index (YI) is calculated according to ASTM E313.

[0153] The gloss level is measured on platelets having dimensions of 60 mm40 mm2 mm and produced at a melt temperature of 260 C./300 C. in an injection mold. The measurement is performed in reflection at a measuring angle of 60 according to DIN 67530.

[0154] Serving as further important parameters for characterizing process stability are the absolute changes in the yellowness index and in the gloss level upon increasing the melt temperature in the injection mold from 260 C. to 300 C. which are calculated according to

Yellowness index (260 C..fwdarw.300 C.)=yellowness index (300 C.)yellowness index (260 C.)

and

Gloss level (260 C..fwdarw.300 C.)=gloss level (300 C.)gloss level (260 C.).

[0155] What is assessed is whether the yellowness index measured on test specimens produced at a melt temperature in the injection mold of 260 C. is smaller than 25 and whether the gloss level of these test specimens is greater than 95. Also assessed is whether the absolute changes in the yellowness index and in the gloss level upon increasing the processing temperature in the injection mold from 260 C. to 300 C. are each less than 10. This corresponds to customary requirement profiles for molding materials stable during processing and intended for coloring and high-gloss applications.

[0156] Serving as a measure for the hydrolysis resistance of the compositions is the relative change in the MVR measured according to ISO 1133 at 260 C. with a die load of 5 kg with a hold time of 5 min upon storage of the pelletized material for 7 days under hot and humid conditions (HH storage) at 95 C. and 100% relative humidity. The relative increase in the MVR value relative to the MVR value before the storage in question is calculated as MVR(hydr) which is defined by the formula below:

[00001]$.Math..Math.\mathrm{MVR}\left(\mathrm{hyrdr}\right)=\frac{\mathrm{MVR}\left(\mathrm{after}.Math..Math.\mathrm{HH}.Math..Math.\mathrm{storage}\right)-\mathrm{MVR}\left(\mathrm{before}.Math..Math.\mathrm{storage}\right)}{\mathrm{MVR}\left(\mathrm{before}.Math..Math.\mathrm{storage}\right)}.Math.100.Math.\%.$

[0157] The propensity for formation of surficial defects with blistering topology is determined on sheets having a geometry of 150 mm105 mm3.2 mm and high-gloss surfaces on both sides. These sheets generally exhibit no blistering whatsoever immediately after injection molding. Blistering is assessed visually without using magnifying technical aids (microscopes, magnifying glasses etc.) after three-day storage of these sheets under hot and humid conditions at 40 C. and a relative humidity of >95%. All visually apparent blister defects on both sides of altogether two sheets having the above-defined dimensions (i.e. on an effective surface area of 4.Math.15 cm.Math.10.5 cm=630 cm.sup.2) are counted. From experience this purely visual assessment without magnifying technical aids accounts for all defects having a diameter above approximately 100-200 m. What is assessed is whether this counting reveals less than 10 blister defects, which corresponds to a generally acceptable quality.

TABLE-US-00001 TABLE 1 Component 1 1b V2 V3 V4 V4b V5 V6 V7 V8 A Polycarbonate 60.28 60.28 60.28 60.28 60.28 60.28 60.28 60.32 60.32 60.32 B1 EDTA 0.05 0.05 B2 Phenylphosphonic acid 0.05 B3 Citric acid 0.05 B4 Oxalic acid 0.05 0.05 B5 Terephthalic acid 0.05 B6 Phosphorous acid 0.01 B7 Ca(H2PO4)2 0.05 B8 p-Toluenesulfonic acid 0.05 C ABS 38.61 38.61 38.61 38.61 38.61 38.61 38.61 38.61 38.61 38.61 D1 Demolding agent 0.74 0.74 0.74 0.74 0.74 0.74 0.74 0.74 0.74 0.74 D2 Stabilizer 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 0.12 D3 Stabilizer 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 0.20 Compounding conditions Speed [rpm] 220 500 220 220 220 500 220 220 220 220 Properties MVR(300 C./5 kg/5 min) [ml/10 min] 61 68 61 59 61 72 60 54 60 59 iMVR(300 C./5 kg/15 min) [ml/10 min] 61 72 66 61 62 96 61 57 60 60 MVR(300 C./5 kg, 5 min-->15 min) 0% 6% 8% 3% 2% 33% 2% 6% 0% 2% MVR(hydr) [%] 58 58 363 59 64 50 68 58 48 96 Yellowness index (260 C.) < 25 yes yes yes yes yes yes yes yes yes Yellowness index (260 C.-->300 C.) < 10 yes yes yes yes yes yes yes yes yes Gloss level @ 60 (260 C.) > 95 yes yes yes yes yes yes yes yes yes Gloss level @ 60 (260 C.-->300 C.) < 10 yes yes yes no yes yes yes yes no Blistering (<10 blisters/630 cm.sup.2) yes yes no no yes no no no no

[0158] The examples in table 1 show that only the inventive molding materials according to example 1/1b produced with and containing EDTA as an acidic compound fully achieve the object of the invention while the compositions according to comparative examples V2 to V8 produced with acids according to the prior art all diverge from the target profile of properties at least in terms of one required property.

[0159] Compositions produced with phenylphosphonic acid (V3) show unsatisfactory hydrolysis stability and unsatisfactory blistering behavior.

[0160] Compositions produced with citric acid (V2) show unsatisfactory hydrolysis stability and unsatisfactory blistering behavior.

[0161] Compositions produced with oxalic acid (V4/V4b) show increased thermally induced polycarbonate molecular weight degradation already during compounding at elevated melt temperatures (i.e. an unsatisfactory processing window in the production of the compounds) and moreover also unsatisfactory processing stability in injection molding of such compounds produced under more intense thermal conditions with respect to polycarbonate molecular weight degradation.

[0162] Compositions produced with terephthalic acid, phosphorous acid or calcium dihydrogenphosphate (V5-V7) all show unsatisfactory blistering behavior.

[0163] Compositions produced with p-toluenesulfonic acid (V8) show unsatisfactory hydrolysis and gloss level stability and unsatisfactory blistering behavior.