FILLED POLYCARBONATE COMPOSITION HAVING LOW THERMAL EXPANSION

Abstract

The present invention relates to a thermoplastic composition, comprising: A) aromatic polycarbonate and B) Ba) reinforcing fibers and/or Bb) spherical particles of oxides of metals or metalloids of the 3rd main group, 4th main group and/or 4th transition group. The composition further comprises: C) PMMI copolymer and D) phosphite stabilizer and/or phosphine stabilizer, wherein, furthermore, the proportion of B) is ≥35% by weight to ≤40% by weight and the proportion of C) is >0.1% by weight in each case based on the total weight of the composition.

The invention further relates to a layered arrangement comprising a substrate layer and a reflection layer distinct from the substrate layer and at least partially covering the substrate layer, wherein the reflection layer at least partially reflects light in the wavelength range from 380 nm to 750 nm, an illumination apparatus comprising a light source and a reflector, wherein the reflector is arranged such that at least a portion of the light transmitted by the light source is reflected by the reflector, and to a process for producing a molded article.

Claims

1.-15. (canceled)

16. A thermoplastic composition, comprising: A) aromatic polycarbonate and B) Ba) reinforcing fibers and/or Bb) spherical particles of oxides of metals or metalloids of the 3rd main group, 4th main group and/or 4th transition group, wherein the composition further comprises: C) PMMI copolymer and D) phosphite stabilizer and/or phosphine stabilizer, wherein, furthermore, the proportion of B) is ≥35% by weight to ≤60% by weight and the proportion of C) is >0.1% by weight in each case based on the total weight of the composition.

17. The composition as claimed in claim 16, wherein the aromatic polycarbonate A) is the homopolycarbonate based on bisphenol A, the homopolycarbonate based on 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, a copolycarbonate based on the monomers bisphenol A and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane or a mixture of at least two of the abovementioned polymers.

18. The composition as claimed in claim 16, wherein component B) is Bb) spherical quartz having an average diameter d.sub.50 of ≥3 μm to ≤5 μm and an average diameter d.sub.98, in each case determined according to ISO 13320:2009, of ≥10 μm to ≤15 μm and/or Ba) glass fibers having a cut length of ≥2 mm to ≤5 mm and a cross sectional ratio of ≥1:1 to ≤2:1.

19. The composition as claimed in claim 16, wherein the proportion of C) is ≤0.5% by weight based on the total weight of the composition.

20. The composition as claimed in claim 16, wherein the glass transition temperature of the PMMI copolymer C) determined according to DIN EN ISO 11357-2:2014-07 at a heating rate of 20° C./min is ≥120° C. to ≤170° C.

21. The composition as claimed in claim 16, wherein D) is tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, triphenylphosphine or a mixture containing at least one of the abovementioned compounds.

22. The composition as claimed in claim 16, wherein the proportion of D) is ≥0.01% by weight to ≤0.5% by weight based on the total weight of the composition.

23. The composition as claimed in claim 16, wherein the composition contains the spherical particles Bb) and has a coefficient of linear thermal expansion (CLTE) determined according to DIN 53752:19080-12 and measured in a temperature range of 23-60° C. of ≥20 ppm/K to ≤50 ppm/K.

24. The composition as claimed in claim 16, comprising, based on the total weight of the composition: ≥55% by weight to ≤65% by weight of A), ≥35% by weight to ≤45% by weight of B), ≥0.2% by weight to ≤0.5% by weight of C) and ≥0.01% by weight to ≤0.1% by weight of D), wherein the parts by % by weight sum to ≤100% by weight.

25. A layered arrangement comprising a substrate layer and a reflection layer distinct from the substrate layer and at least partially covering the substrate layer, wherein the reflection layer at least partially reflects light in the wavelength range from 380 nm to 750 nm, wherein the substrate layer contains a composition as claimed in claim 16.

26. The layered arrangement as claimed in claim 25, wherein the reflection layer is a metal layer.

27. The layered arrangement as claimed in claim 25, wherein the reflection layer has a thickness of ≥10 nm to ≤100 nm.

28. The layered arrangement as claimed in claim 25, wherein the layered arrangement is not planar.

29. An illumination apparatus comprising a light source and a reflector, wherein the reflector is arranged such that at least a portion of the light emitted by the light source is reflected by the reflector, wherein the reflector contains a layered arrangement as claimed in claim 25.

30. A process for producing a molded article, wherein a thermoplastic composition is molded to afford the molded article under the influence of heat, wherein the thermoplastic composition is a composition as claimed in claim 16.

Description

EXAMPLES

[0080] The present invention is more particularly elucidated with reference to the following examples without, however, being limited thereto.

Polymers:

[0081] A1: is a commercially available polycarbonate based on bisphenol A having an MVR of 19 cm.sup.3/10 min (300° C./1.2 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 145° C. (Makrolon® 2408 from Covestro Deutschland AG). The molecular weight M.sub.w was approx. 23 887 g/mol.

[0082] A2: is a commercially available copolycarbonate based on bisphenol A and bisphenol TMC having an MVR of 18 cm.sup.3/10 min (330° C./2.16 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 183° C. (Apec® 1895 from Covestro Deutschland AG). The molecular weight M.sub.w was approx. 27 855 g/mol.

Fillers:

[0083] B1: is a spherical fused quartz from Quarzwerke GmbH (50226 Frechen, Germany) which is available under the trade name Amosil FW600 (D.sub.50=4 μm, D.sub.98=13 μm, unsized). This is a fired silicon dioxide having a D.sub.10/D.sub.90 ratio of about 1.5/10 μm and a specific surface area of about 6 m.sup.2/g determined according to DIN ISO 9277 (DIN-ISO 9277:2014-01).

[0084] B2: is a glass fiber from Nittobo (2-4-1, Kojimachi, Chiyoda-ku, Tokyo 102-8489, Japan) which is available under the trade name CSG 3PA-830. This is a flat glass fiber having a 3 mm cut length and a cross sectional ratio of 1.4.

Stabilizers:

[0085] C1: is a commercially available copolymer based on polymethacryloylmethylimide (Pleximid® 8803) having a softening temperature (VST/B 50; ISO 306:2013) of 130° C.

[0086] C2: is a commercially available copolymer based on polymethacryloylmethylimide (Pleximid® TT50) having a softening temperature (VST/B 50; ISO 306:2013) of 150° C.

[0087] D1: is a phosphite from Adeka which is available under the trade name ADK-Stab-Pep36 (CAS No. 80693-00-1; bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite).

[0088] D2: Triphenylphosphine (CAS No. 603-35-0) from BASF.

[0089] D3: is a stabilizer mixture (80% Irgafos168; s. D4)+20% Irganox1076; phenolic antioxidant; CAS No. 2082-79-3) from BASF (Ludwigshafen) which is commercially available under the trade name Irganox B900.

[0090] D4: is a phosphite from BASF available under the trade name Irgafos 168 (CAS No. 31570-04-4).

[0091] D5: is a phosphite from Dover Chemical Corporation available under the trade name Doverphos S9228 (CAS No. 154862-43-8).

Demolding Agent:

[0092] E1: PETS (pentaerythritol tetrastearate)

Production Conditions:

[0093] Method A: BUSS kneader, melt temperature: 280-300° C., speed: 350 rpm, throughput: 75 kg/h, torque: 30%, filler addition via side extruder.

[0094] Method B: ZE 25 AX 40D-UTX twin-screw extruder from Berstorff, extruder melt temperature: 300° C. (320° C. for polymer A2), extruder speed: 225 rpm, throughput: 20 kg/h, torque: 50-60%, filler addition via side extruder on housing 5 (of 9).

Procedure:

[0095] Production of the polycarbonate compositions was carried out using either a BUSS kneader (method A) or a twin screw extruder (method B). Depending on the apparatus the processing temperatures were between 280-300° C. at a speed of 225 min.sup.−1 or 350 min.sup.−1. The employed filler was supplied via a side extruder and the polycarbonate and the powder premixture containing all further additives were added via the main feed.

[0096] After sufficient drying of the granulates the test specimens were produced by injection molding at a processing temperature of the melt of 290-330° C. and in the case of Apec®-containing molding materials of 310-350° C.

[0097] The CLTE values were determined by thermomechanical analysis (TMA) according to DIN 53752:1980-12 in the range between room temperature and 60° C. on test specimens having dimensions of 10 mm×10 mm×4 mm.

[0098] Molecular weights Mw were determined as follows: Gel permeation chromatography, calibrated against bisphenol A polycarbonate standards, using dichloromethane as eluent. Calibration with linear polycarbonates (formed from bisphenol A and phosgene) of known molar mass distribution from PSS Polymer Standards Service GmbH, Germany, calibration by method 2301-0257502-09D (2009, German language) from Currenta GmbH & Co. OHG, Leverkusen. The eluent is dichloromethane. Column combination of crosslinked styrene-divinylbenzene resins. Diameter of analytical columns: 7.5 mm; length: 300 mm. Particle sizes of column material: 3 μm to 20 μm. Concentration of solutions: 0.2% by weight. Flow rate: 1.0 ml/min, temperature of solutions: 30° C. Injection volume: 100 μl. Detection by means of UW detector.

[0099] The reported compositions are numbered consecutively. A “V” denotes a comparative example and an “E” denotes an inventive example.

Compounding According to Method A and Subsequent Injection Molding Experiments with Phosphite/PMMI:

TABLE-US-00001 TABLE 1 Changes in the molecular weight of polycarbonate measured after compounding and after injection molding at different melt temperatures. No. V-1 V-2 V-3 V-4 E-5 E-6 V-7 V-8 A1 59.5 59.425 59.325 59.35 59.35 59.35 59.475 59.325 B1 40 40 40 40 40 40 40 40 E1 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 C1 0.1 0.2 D1 0.075 0.15 0.25 0.25 0.15 0.05 D2 0.025 0.025 0.025 0.025 0.025 D3 0.1 0.25 Longitudinal/ 46/48 transverse CLTE (ppm/K) Mw (g/mol) Comp.: 21 820 22 390 22 550 22 620 23 140 23 070 20 890 20 930 ΔM.sub.w comp. 8.65 6.27 5.60 5.30 3.13 3.42 12.55 12.38 (%).sup.3 Injection molding: 290° C. 19 820 23 080 300° C. 19 390 22 340 310° C. 18 910 22 080 320° C. 19 380 21 550 330° C. 18 380 20 930 .sup. 18 500.sup.2 .sup. 18 410.sup.2 ΔM.sub.w SG 23.05 12.38 22.55 22.93 (%).sup.1 .sup.1Difference between molecular weight of polycarbonate before compounding and of the respective composition after processing by injection molding at 330° C. .sup.2Measured on polymer strands after rheology measurement at 330° C. .sup.3Difference between molecular weight of polycarbonate before and after compounding.

[0100] From table 1 it is initially apparent that the molecular weight of polycarbonate is less severely reduced in the compounding process with increasing content of D1 (compositions 1-3). However, above 0.15% of component D1 there is no longer a big difference. Omitting D2 as a processing stabilizer has no effect on molecular weight (cf. V-3/V-4). The addition of C1 reduces molecular weight degradation during compounding (cf. E-5 with V-2). Increasing the C-1 content further reduces the phosphite amount (cf. E-6 with V-1). The use of another customary process stabilizer (D3) shows much more severe molecular weight degradation (cf. V-7 with V-1 and V-8 with V-3).

[0101] In terms of processing stability in the downstream process (injection molding) the differences are even clearer. Thus, composition E-6 which contains both phosphite and PMMI is markedly more stable to molecular weight degradation than composition V-3 which contains only the phosphite. Stability is demonstrated over a temperature range which is very wide and relevant for this material (high filler contents require a greater melt temperature to ensure flowability).

[0102] The results thus show a synergistic effect of phosphite and PMMI.

Compounding According to Method B and Subsequent Injection Molding Experiments with Phosphite/PMMI:

TABLE-US-00002 TABLE 2 Changes in the molecular weight of polycarbonate measured after compounding and after injection molding at different melt temperatures. Mol % phosphorus No. (.Math.10.sup.−4) E-9 E-10 E-11 E-12 V-13 V-14 V-15 A1 59.35 59.35 59.35 59.05 59.05 59.4 59.35 B1 40 40 40 40 40 40 40 E1 0.4 0.4 0.4 0.4 0.4 0.4 0.4 C1 0.2 0.2 0.2 0.2 0 0.2 0 D1 1.6 0.05 0.05 0 0.25 D2 1.9 0.05 D4 0.77 0.05 D5 1.2 0.05 Mw (g/mol) Comp.: 23 400 23 500 23 500 23 400 23 070 23 180 23 080 ΔM.sub.w comp. 2.04 1.62 1.62 2.04 3.42 2.96 3.38 (%).sup.2 Injection molding: 290° C. 23 560 23 110 23 190 22 800 21 950 22 910 22 060 310° C. 23 000 22 670 22 890 22 430 21 480 22 420 21 580 330° C. 22 490 22 290 22 440 22 300 21 200 22 080 20 860 ΔM.sub.w SG 5.85 6.69 6.06 6.64 11.25 7.56 12.67 (%).sup.1 .sup.1Difference between molecular weight of polycarbonate before compounding and of the respective composition after processing at 330° C. .sup.2Difference between molecular weight of polycarbonate before and after compounding.

[0103] It is apparent from the data in table 2 that there is a synergistic effect of phosphite/phosphine and PMMI in respect of process stabilization. This applies to a series of different P-based heat stabilizers (D4 shows the highest effectiveness measured by the molecular amount of active P species). The differences at a content of 0.2% by weight of C1 are low but it is especially shown that the absence of PMMI results in a marked deterioration of ΔMw from 5.9% to 11.3% (cf. for example V-13 with E-9). Comparing the molecular weights after extrusion makes it clear that the compositions containing both phosphite and PMMI are less severely damaged than the compositions V-13 and V-14. Despite a similar percentage decrease of the Mw for V-14 the final value at the respective processing temperature is thus lower than for the inventive compositions. Increasing the phosphite content (V-15) moreover interestingly results in a marked deterioration relative to V-13.

Investigation into Effect of PMMI Concentration:

TABLE-US-00003 TABLE 3 Changes in the molecular weight of polycarbonate measured after compounding and after injection molding at different melt temperatures. Examples V-13 and E-9 are reported again for comparative purposes. Composition V-13 V-16 E-9 E-17 E-18 A1 59.55 59.45 59.35 59.05 59.35 B1 40   40   40   40   40   E1 0.4 0.4 0.4 0.4 0.4 C1 0.1 0.2 0.5 C2 0.2 D1  0.05  0.05  0.05  0.05  0.05 Mw (g/mol) Comp.: 23 070    23 260    23 400    23 560    23 370    ΔM.sub.w comp. (%).sup.2  3.42  2.62  2.04  1.37  2.16 Injection molding: 290° C. 21 950    23 040    23 560    23 760    23 190    310° C. 21 480    22 520    23 000    23 510    22 980    330° C. 21 200    21 870    22 490    23 400    22 440    ΔMw (%).sup.1 11.25  8.44  5.85  2.04  6.06 .sup.1Difference between molecular weight of polycarbonate before compounding and of the respective composition after processing at 330° C. .sup.2Difference between molecular weight of polycarbonate before and after compounding.

[0104] It is apparent from the data in table 3 that an increase in the concentration of C1/C2 brings about a marked improvement in respect of processing stability (ΔM.sub.w). At a PMMI content of 0.5% by weight the molecular weight of the polycarbonate compound has fallen by only 1% (the optimal upper limit is 0.5% by weight). This effect is also apparent when using C2 in example E-18.

Effect of Filler Content: +Further Fillers (Glass Fiber, 30-50% SiO.SUB.2.); Production According to Method B:

[0105]

TABLE-US-00004 TABLE 4 Changes in the molecular weight of polycarbonate measured after compounding and after injection molding at different melt temperatures. Example E-9 is reported again for comparative purposes. Composition V-19 E-20 E-21 E-9 V-22.sup.C V-23.sup.C V-24 E-25 A1 69.35 69.35 64.35 59.55 54.19 49.19 59.35 59.35 B1 30 30 35 40 45 50 B2 40 40 E1 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 C1 0.2 0.2 0.2 0.2 D1 0.25 0.05 0.05 0.05 0.25 0.25 0.25 0.05 Longitudinal/ 51/53 46/48 40/43 38/40 19/60 transverse CLTE (ppm/K) Mw (g/mol) Comp.: 23 690 23 400 23 120 22 670 ΔM.sub.w comp. 0.82 2.04 3.21 5.09 (%).sup.2 Injection molding: 290° C. 23 060 23 570 23 500 23 560 21 790 23 150 310° C. 22 310 23 380 23 170 23 000 21 560 22 980 320° C. 21 200 22 640 330° C. 21 800 23 150 22 930 22 490 21 260 20 270 20 760 ΔMw (%).sup.1 8.74 3.08 4.01 5.85 10.99 15.14 11.25* 5.22* .sup.1Difference between molecular weight of polycarbonate before compounding and of the respective composition after processing at 330° C. .sup.2Difference between molecular weight of polycarbonate before and after compounding. .sup.CIncludes 0.16% by weight of carbon black. *Difference measured after injection molding at a melt temperature of 320° C.

Effect in Copolycarbonate:

[0106]

TABLE-US-00005 TABLE 5 Changes in the molecular weight of (co)polycarbonate measured after compounding and after injection molding at different melt temperatures. Composition E-9 E-29.sup.2 V-30 V-31 A1 59.55  5.00 A2 54.35 59.55 59.55 B1 40   40   40   40   E1 0.4 0.4 0.4 0.4 C1 0.2 0.2 D1  0.05  0.05  0.05  0.25 Mw (g/mol) Comp.: 23 400    26 400    25 730    25 750    ΔM.sub.w comp. (%).sup.3  2.04  5.22  7.63  7.56 Injection molding: 290° C. 23 560    310° C. 23 000    25 880    24 560    24 060    330° C. 22 490    25 510    24 110    24 120    350° C. 24 670    23 280    23 710    ΔMw (%).sup.1a  5.85  8.88 13.44 13.41 ΔMw (%).sup.1b 11.43 16.42 14.88 .sup.1aDifference between molecular weight of polycarbonate before compounding and of respective composition after processing at 330° C. .sup.1bDifference between molecular weight of polycarbonate before compounding and of respective composition after processing at 350° C. .sup.2The melt temperature during compounding was 320° C. .sup.3Difference between molecular weight of polycarbonate before and after compounding.

[0107] The effect is likewise clearly apparent in A2 (Apec®). Increasing the content of stabilizer D1 only shows a slight improvement (cf. V-31 and V-30) in molecular weight degradation at a processing temperature of 350° C. but said degradation is still markedly higher than in E-29.