High-temperature (co)polycarbonates with improved rheological properties

Abstract

The invention relates to (co)polycarbonate compositions and molding compounds, characterized by improved rheological properties and a high heat deflection temperature.

Claims

1. A composition comprising A) from 99.9 to 92 parts by weight (based on the sum of components A+B) of high molecular weight, thermoplastic, aromatic (co)polycarbonate having a molecular weight Mw (weight average) of at least 10 000 g.Math.mol.sup.−1 and comprising structural units of formula (I), ##STR00008## where R.sup.a and R.sup.b each independently of one another represent hydrogen or C.sub.1-C.sub.4 alkyl, k represents 0, 1, 2, 3 or 4 B) from 0.1 to 8 parts by weight (based on the sum of components A+B) of one or more organically modified telechelic or comb polysiloxanes selected from the group consisting of polysiloxanes of general formulae (IIa) and (IIb) ##STR00009## where the radicals R.sup.1 in a molecule are identical or different and represent alkyl radicals comprising from 1 to 4 carbon atoms, A are identical or different and represent —R.sup.2—X, where R.sup.2 is a radical having the general formula (IIc) ##STR00010## R.sup.3 is a divalent alkyl or alkenyl radical comprising from 2 to 11 carbon atoms, R.sup.4 are identical or different at each occurrence and are divalent alkyl or aralkyl radicals, x independently of one another has a value of 0 or 1, y independently of one another has a value of from 0 to 100 and X is an amino group, n, k and r each independently of one another represent a number between 0 and 200, subject to the proviso that n, k and r are not all 0; and C) optionally additives.

2. The composition as claimed in claim 1, wherein the (co)polycarbonate A) has a molecular weight Mw (weight average) of from 15 000 g mol.sup.−1 to 300 000 g.Math.mol.sup.−1.

3. The composition as claimed in claim 1, wherein component A) is employed in amounts of from 99.7 to 94 parts by weight and component B) is employed in amounts of from 0.3 to 6 parts by weight (based on the sum of components A+B).

4. The composition as claimed in claim 1, wherein the composition comprises an additive, a UV absorber, a demolding auxiliary or a heat stabilizers, in an amount of from 50 to 5000 ppm by weight in each case, based on the sum of components A+B.

5. The composition as claimed in claim 1, wherein the structural unit of formula (I) comprises the following structure (IX) ##STR00011##

6. A process for producing the composition as claimed in claim 1 comprising mixing the constituents to form a mixture and melt compounding and melt extruding the mixture at elevated temperature.

7. A method for producing a molded part utilizing the compositions as claimed in claim 1.

8. A molded parts comprising the composition as claimed in claim 1.

9. A method for producing blend comprising mixing A), B) and optionally C) of the composition as claimed in claim 1.

Description

EXAMPLES

(1) Production of the compounds employed the following raw materials.

(2) PC-1 nat.: Heat-stabilized, demolding agent-containing copolycarbonate of bisphenol TMC and BPA from Bayer Material-Science AG, Leverkusen, having an MVR of 18 cm.sup.3/10 min (330° C., 2.16 kg) and a Vicat temperature of 182° C. Tegomer® A-Si 2322: alpha, omega-amine-terminated siloxane from Evonik Industries AG, Essen.

(3) A multi-screw extruder was used to produce various test mixtures of the amine-terminated siloxane Tegomer® A-Si 2322 with the base copolycarbonate PC-1 at a temperature of 330° C.

(4) As a control, the mechanical and thermal properties of the blends are subjected to the customary tests such as Vicat temperature, HDT, tensile test, modulus of elasticity and impact resistance using PC-1 nat. without additives. A summary of all properties is contrasted with the comparative example (sample without additives) in Table 1 which follows.

(5) As a measure for the heat distortion resistance the Vicat softening temperature VST/B50 was determined according to ISO 306 on 80×10×4 mm test specimens with a needle load of 50 N and a heating rate of 50° C./h using a Coesfeld Eco 2920 instrument from Coesfeld Materialtest.

(6) Determination of the melt volume-flow rate (MVR) was carried out according to ISO 1133 (at a test temperature of 300° C., mass 1.2 kg) using a Göttfert MI-ROBO 8998 instrument from Göttfert or a Zwick 4106 instrument from Zwick Roell.

(7) The Charpy notched impact strength was measured according to ISO 7391/179A using single-side injected 80×10×4 mm test rods at room temperature.

(8) TABLE-US-00001 TABLE 1 Formulation: -1 -2 -3 -4 PC-1 % 100 98.5 97 95.5 Tegomer A-Si 2322 % — 1.5 3 4.5 Rheological properties MVR 330° C./2.16 kg ml/10 min 16.3 35.2 45.6 64.6 IMVR20′ 330° C./2.16 kg ml/10 min 17.3 38.8 56.2 74.9 Delta MVR/IMVR20′ 1.0 3.6 10.6 10.3 Vicat VSTB 120 ° C. 182.0 178.0 175.5 172.0

(9) It is clearly apparent that the MVR is significantly increased due to the addition of the siloxane, i.e. the melt viscosity is reduced and the flowability is thus increased.

(10) Addition of the liquid additive slightly reduces the Vicat temperature though said temperature remains within a high range.

(11) TABLE-US-00002 TABLE 2 Formulation: -1 -2 -3 -4 PC-1 % 100 98.5 97 95.5 Tegomer A-Si 2322 % — 1.5 3 4.5 Melt viscosity @ 300° C. 50 Pas 1621 704 533 370 100 Pas 1481 661 490 331 200 Pas 1314 575 387 272 500 Pas 927 403 257 188 1000 Pas 636 299 178 136 1500 Pas 501 236 148 110 5000 Pas 185 112 83 52 Melt viscosity @ 320° C. 50 Pas 741 394 316 215 100 Pas 720 380 302 213 200 Pas 673 331 267 188 500 Pas 540 251 178 134 1000 Pas 405 191 132 92 1500 Pas 326 162 110 78 5000 Pas 152 83 66 39 Melt viscosity @ 330° C. 50 Pas 545 264 200 138 100 Pas 532 257 193 134 200 Pas 506 248 182 126 500 Pas 426 194 149 95 1000 Pas 335 146 107 71 1500 Pas 275 125 86 61 5000 Pas 133 70 51 31 Melt viscosity @ 340° C. 50 Pas 393 180 126 99 100 Pas 387 179 125 97 200 Pas 376 178 118 90 500 Pas 323 150 110 72 1000 Pas 265 117 88 54 1500 Pas 225 98 73 45 5000 Pas 112 56 42 24 Melt viscosity @ 360° C. 50 Pas 208 93 66 55 100 Pas 205 92 65 53 200 Pas 199 90 64 51 500 Pas 184 87 63 47 1000 Pas 163 77 56 38 1500 Pas 146 68 50 34 5000 Pas 84 48 30 19

(12) It is apparent from the melt viscosities that addition of the siloxane achieves a marked improvement in flowability over the entire range of shear and at different temperatures.

(13) TABLE-US-00003 TABLE 3 Formulation: -1 -2 -3 -4 PC-1 % 100 98.5 97 95.5 Tegomer A-Si 2322 % — 1.5 3 4.5 Spiral flow cm 25 33 40 to 41.5 44.5 to 46

(14) It is apparent from the spiral flow values that addition of the siloxane achieves a marked improvement in flowability.

(15) TABLE-US-00004 TABLE 4 Formulation: -1 -2 -3 -4 PC-1 % 100 98.5 97 95.5 Tegomer A-Si 2322 % — 1.5 3 4.5 Mechanical properties Charpy notched impact kJ/m.sup.2 9 s 8 s 8 s 9 s ISO7391/179A Yield stress N/mm.sup.2 73 72 71 69 Yield strain % 6.7 6.5 6.4 6 Ultimate tensile strength N/mm.sup.2 62 57 55 60 Modulus of elasticity N/mm.sup.2 2432 2390 2354 2333

(16) It is apparent from these values that the mechanical properties are largely retained despite large amounts of a liquid additive being added.