OPAQUE MULTI-LAYER BODY MADE OF POLYCARBONATE AND HAVING WEATHERING STABILITY

Abstract

The invention relates to opaque colored multilayer articles having a substrate layer based on polycarbonate or polymethylmethacrylate. The compositions of the substrate layer contain a titanium dioxide having particular properties as white pigment. Compared to the Kronos® 2230 white pigment which is conventionally used as white pigment for corresponding compositions and has more particularly been specially matched to polycarbonate, it is possible to achieve considerably higher weathering stability of the colored shaped bodies provided that a UV absorber-containing coating has been applied to the substrate layer. Color stability and gloss are maintained even after weathering, and brilliant colors can thus be assured.

Claims

1.-15. (canceled)

16. A multilayer article comprising a) a substrate layer having light transmittance in the range from 380 to 780 nm of less than 0.5%, determined at a sheet thickness of 4 mm to DIN ISO 13468-2:2006 (D65, 10°), consisting of a thermoplastic composition based on polymethylmethacrylate or aromatic polycarbonate, comprising i) titanium dioxide white pigment, wherein the titanium dioxide present in the composition of the substrate layer has a rutile content of at least 60% by weight and wherein the titanium dioxide has a coating containing silicon dioxide and aluminum oxide and optionally titanium dioxide, and wherein the ratio of the sum total of the aluminum content and silicon content in atom %, determined by means of x-ray photon electron spectroscopy, in the coating to the titanium content in atom %, determined by means of x-ray photon electron spectroscopy, in the coating is greater than 5:1, ii) at least two colorants that are either one organic colorant and one inorganic colorant or two organic colorants, wherein the inorganic colorant is not a titanium dioxide and not a carbon black, b) optionally a primer layer and c) a topcoat layer, wherein the primer layer and/or the topcoat layer includes at least one UV absorber, characterized in that the titanium dioxide present in the composition of the substrate layer has a median particle size D.sub.50, determined by means of scanning electron microscopy, of ≥0.3 μm.

17. The multilayer article as claimed in claim 16, wherein the topcoat layer comprises at least one UV absorber from the group of the benzophenones, resorcinols, 2-(2-hydroxyphenyl)benzotriazoles, hydroxyphenyl-s-triazines, 2-cyanoacrylates and/or oxalanilides.

18. The multilayer article as claimed in claim 16, wherein the total concentration of colorants in the thermoplastic composition of the substrate layer, excluding titanium dioxide, is 0.012% to 1.2% by weight.

19. The multilayer article as claimed in claim 16, wherein the titanium dioxide has a median particle size D.sub.50, determined by means of scanning electron microscopy, of 0.6 μm to 1.2 μm.

20. The multilayer article as claimed in claim 16, wherein the ratio of the sum total of the aluminum content and silicon content in atom % in the titanium dioxide coating to the titanium content in atom % in the titanium dioxide coating is at least 15:1.

21. The multilayer article as claimed in claim 16, wherein the titanium dioxide has a median particle size D.sub.50, determined by means of scanning electron microscopy, of 0.65 μm to 1.15 μm and the ratio of the sum total of the aluminum content and silicon content in atom % in the titanium dioxide coating to the titanium content in atom % in the titanium dioxide coating is at least 19:1.

22. The multilayer article as claimed in claim 16, wherein the thermoplastic composition of the substrate layer contains 0.1% to 0.6% by weight of at least one UV absorber.

23. The multilayer article as claimed in claim 16, wherein the thermoplastic composition of the substrate layer contains 2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol as UV absorber.

24. The multilayer article as claimed in claim 16, wherein the amount of titanium dioxide in the thermoplastic composition of the substrate layer is 0.1% to 1.5% by weight.

25. The multilayer article as claimed in claim 16, wherein the at least one organic colorant is selected from the group consisting of: ##STR00013## ##STR00014## where Rc and Rd are independently a linear or branched alkyl radical or halogen, n independently of the respective R is a natural number from 0 to 3, where the radical is hydrogen when n=0, ##STR00015## and at least one red and/or violet colorant selected from the group consisting of the colorants of formulae (7), (8), (9), (10), (11), (12a), (12b) and/or (13) ##STR00016## where R is selected from the group consisting of H and p-methylphenylamine radical, ##STR00017## where Ra and Rb are independently a linear or branched alkyl radical or halogen, n independently of the respective R is a natural number from 0 to 3, where the radical is hydrogen when n=0, ##STR00018## optionally one or more further colorants selected from the group consisting of the yellow and orange colorants of the formulae (14), (15), (16), (17) and/or (18) ##STR00019## the colorant Amaplast Yellow GHS with CAS number 13676-91-01, and those from the Heliogen Blue series and the Heliogen Green series.

26. The multilayer article as claimed in claim 16, wherein the topcoat layer is polysiloxane-based and comprises a combination of an organomodified silane with a silica sol, and wherein the topcoat layer comprises silicon dioxide particles.

27. The multilayer article as claimed in claim 16, wherein the thickness of the substrate layer is 1.0 to 6.0 mm.

28. The multilayer article as claimed in claim 16, wherein the multilayer article is a pipe element, part of a window frame, part of a housing of an electrical switchgear box, part of an antenna, a lamp cover, a watering can, a housing part of a tool or toolbox, part of a toy or play equipment, an antenna or antenna element, or a housing or part of a housing of a mobile communications base station.

29. The multilayer article as claimed in claim 16, wherein the multilayer article is an element of an outer vehicle skin.

30. A method comprising utilizing white pigment titanium dioxide having a rutile content of at least 60% by weight and a median particle size D.sub.50, determined by means of scanning electron microscopy, of ≥0.3 μm, and having a coating comprising silicon dioxide, aluminum oxide and optionally titanium dioxide, wherein the ratio of the sum total of the aluminum content and silicon content in atom % in the coating to the titanium content in atom % in the coating, determined by means of x-ray photon electron spectroscopy, is greater than 5:1, in a substrate layer in combination with a coating comprising a topcoat layer and optionally a primer layer, wherein the topcoat layer and/or the primer layer includes at least one UV absorber, and achieving weathering stability, expressed by a change in the color values a*, b*, L* after artificial weathering for 2500 h with xenon illumination at 0.75 W at 340 nm to ASTM G 155-13 of ΔL*<1.5, Δa*<1.5 and Δb*<1.5, of colored multilayer articles comprising a) the substrate layer having light transmittance in the range from 380 to 780 nm of less than 0.5%, determined at a sheet thickness of 4 mm to DIN ISO 13468-2:2006 (D65, 10°), consisting of a thermoplastic composition based on polymethylmethacrylate or aromatic polycarbonate and comprising at least two colorants that are either one organic colorant and one inorganic colorant or two organic colorants, wherein the inorganic colorant is not a titanium dioxide and not a carbon black, b) the coating comprising the topcoat layer and optionally the primer layer.

Description

EXAMPLES

[0190] There follows a detailed description of the invention with reference to working examples, and the methods of determination described here are employed for all corresponding parameters in the present invention, in the absence of any statement to the contrary.

[0191] Determination Methods:

[0192] The determination methods for the properties specified hereinafter are also applicable elsewhere in the description, unless stated otherwise there. Conversely, the remarks relating to the determination methods in the rest of the examples section are applicable, unless stated otherwise hereinafter.

[0193] Melt volume flow rate (MVR) was determined according to ISO 1133:2012-03 (at a testing temperature of 300° C., mass 1.2 kg) using the Zwick 4106 instrument from Zwick Roell.

[0194] Color in transmission was determined with a Lambda 900 spectrophotometer from Perkin Elmer with a photometer sphere in accordance with ASTM E1348-15 with the weighting factors and formulae described in ASTM E308-08.

[0195] Transmission measurements (transmission in the VIS region, 380 to 780 nm) were conducted on a Lambda 900 spectrophotometer from Perkin Elmer with a photometer sphere according to ISO 13468-2: 2006 (i.e. determination of total transmission by measurement of diffuse transmission and direct transmission).

[0196] Color change: The samples were measured in reflection according to ASTM E 1331-04. This is used to calculate the color values L*, a*, b* in the CIELAB 1976 color space according to ASTM E 308-08 for the D65 illuminant and the 10° observer.

[0197] Yellowness index (Y.I.) was determined according to ASTM E 313-15 (observer: 10°/illuminant: D65) on specimen plaques having a sheet thickness of 4 mm.

[0198] Gloss Measurement

[0199] The surface properties were assessed by conducting gloss measurements. For this purpose, the samples were inserted into a gloss measuring instrument and gloss was measured at 60° (ASTM D 2457-08).

[0200] Artificial weathering with xenon illumination was conducted according to standard ASTM G 155-13 in a CI 5000 xenon weatherometer from Atlas on color specimen plaques (see production of the test specimens). The UV filters used were two borosilicate glass filters. The incident intensity was 0.75 W/m.sup.2/nm at 340 nm. The black standard temperature was 80° C., the sample space temperature 40° C. The samples were irrigated for 18 min every 120 min, with the illumination left switched on during the irrigation phase as well. The aforementioned weathering method is referred to hereinafter as “Xe Wom 0.75 W”.

[0201] Visual color impression is determined by the naked eye using color specimen plaques (see production of the test specimens). For this purpose, the color specimen plaques were viewed before a white background in daylight and assessed correspondingly.

[0202] Materials for Production of the Test Specimens:

Titanium Dioxide for Comparative Examples

[0203] Kronos 2230 from Kronos Worldwide Inc. This titanium dioxide type features the following characteristics: Titanium dioxide of the rutile type in an amount of more than 93.0% by weight in Kronos 2230; median particle diameter (D.sub.50, determined by means of scanning electron microscopy (STEM)) about 0.2 μm. The outer inorganic layer having a thickness of about 10 nm contains a homogeneous mixture of titanium dioxide and silicon/aluminum oxides (determined by means of x-ray photon electron spectroscopy; XPS). The ratio of silicon+aluminum to titanium, in each case in atom %, is about 1:1.

Titanium Dioxide for Inventive Examples

[0204] Altiris 550 from Huntsman. This titanium dioxide type features the following characteristics: Titanium dioxide of the rutile type; median particle diameter (D.sub.50, determined by means of scanning electron microscopy (STEM)) about 0.7 μm, determined by means of scanning electron microscopy (STEM). The outer layer having a thickness of about 10 to 15 nm comprises a mixture of titanium dioxide and silicon/aluminum oxides having an elevated proportion of silicon and aluminum oxides (determined by means of x-ray photon electron spectroscopy; XPS). The ratio of the sum total of silicon+aluminum to titanium, in each case in atom %, in the coating is about 20:1. This ratio is also found at a detection angle of 45°.

[0205] Altiris 800 from Huntsman. This titanium dioxide type features the following characteristics: Titanium dioxide of the rutile type; median particle diameter (D.sub.50, determined by means of scanning electron microscopy (STEM)) about 1.1 μm, determined by means of scanning electron microscopy (STEM). The outer layer having a thickness of about 10-15 nm comprises a mixture of titanium dioxide and silicon/aluminum oxides having an elevated proportion of silicon and aluminum oxides (determined by means of x-ray photon electron spectroscopy; XPS). The ratio of the sum total of silicon+aluminum to titanium, in each case in atom %, in the coating is about 20:1. This ratio is also found at a detection angle of 45°.

[0206] PC1:

[0207] Composition consisting of polycarbonate from Covestro Deutschland AG with an MVR of about 12 cm.sup.3/(10 min), measured at 300° C. with a load of 1.2 kg (to ISO 1133-1:2012-03), based on bisphenol A and terminated by phenol, and 0.20% by weight of Tinuvin 329 (UV absorber) and 0.30% by weight of pentaerythritol tetrastearate (demolding agent).

[0208] PC2:

[0209] Polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/(10 min), measured at 300° C. and load 1.2 kg (to ISO 1133-1:2012-03) and based on bisphenol A and terminated by phenol. The polycarbonate does not contain any further additives.

[0210] PC3:

[0211] Polycarbonate from Covestro Deutschland AG having an MVR of about 6 cm.sup.3/(10 min), measured at 300° C. and load 1.2 kg (to ISO 1133-1:2012-03) and based on bisphenol A and terminated by phenol. The polycarbonate does not contain any further additives.

[0212] PC4:

[0213] Polycarbonate from Covestro Deutschland AG having an MVR of about 12 cm.sup.3/(10 min), measured at 300° C. and load 1.2 kg (to ISO 1133-1:2012-03) and based on bisphenol A and terminated by phenol, containing 0.30% by weight of pentaerythritol tetrastearate (demolding agent).

[0214] Colorants of Structure 12a and 12b with n=0 (No Substituents), 1:1 Mixture:

[0215] An initial charge of 5.62 g (0.025 mol) of benzene-1,2,4,5-tetracarboxylic dianhydride and 7.99 g (0.05 mol) of 1,8-diaminonaphthalene in 75 ml of N-ethylpyrrolidone at room temperature was heated gradually to 150° C. The mixture was stirred at this temperature for 5 hours. After cooling, 125 ml of water was added and the precipitate was filtered off. The precipitate was repeatedly suspended in water and washed in this way. The precipitate was dried under high vacuum at 80° C. The dried precipitate was admixed with a mixture of 50 ml of glacial acetic acid and 25 ml of acetic anhydride. The mixture was boiled under reflux for 4 hours. After cooling, the reaction mixture was added to 500 ml of water. The precipitate was filtered off, washed with water and dried under high vacuum at 80° C. 12.5 g of purple powder was obtained.

[0216] Bayferrox 110 M:

[0217] Micronized, yellowish iron oxide red pigment having CAS number 001309-37-1 from Lanxess Deutschland GmbH.

[0218] Colortherm Red 130M:

[0219] Heat-stable, micronized iron oxide red pigment having CAS number 001309-37-1 from Lanxess Deutschland GmbH.

[0220] Elftex 570 Pearls:

[0221] Carbon black for the coloring of plastics from Cabot Corp.

[0222] Yellow 3G:

[0223] MACROLEX® Yellow 3G, Solvent Yellow 93 pyrazolone dye from Lanxess Deutschland GmbH.

[0224] Heliogen Blue K7104 LW:

[0225] Heliogen® Blue K 7104 LW, copper phthalocyanine-based pigment, Pigment Blue 15:4 with CAS number 147-14-8 from BASF SE, Ludwigshafen, Germany.

[0226] Heliogen Green K8730:

[0227] Chlorinated copper phthalocyanine with CAS number 132-53-5 from BASF SE, Ludwigshafen, Germany.

[0228] Heucodur Blue 2R:

[0229] Cobalt aluminum blue spinel with CAS number 1345-16-0 from Heubach GmbH, Germany.

[0230] Lamp Black 101:

[0231] Carbon black for the coloring of plastics from The Cary Company 1195 W. Fullerton Ave, Addison IL 60101.

[0232] Macrolex Red EG:

[0233] Solvent Red 135 perinone dye from Lanxess Deutschland GmbH.

[0234] Macrolex Yellow 6G:

[0235] Solvent Yellow 179 methine dye from Lanxess Deutschland GmbH.

[0236] Macrolex® Yellow G. Gran.:

[0237] Solvent Yellow 114; Disperse Yellow 54 quinophthalone dye from Lanxess Deutschland GmbH.

[0238] Oracet Yellow 180 (Oracet Yellow GHS):

[0239] Anthraquinone dye, Solvent Yellow 163 from BASF SE, Ludwigshafen, Germany.

[0240] Paliogen Blue 6385:

[0241] Paliogen Blue L 6385 (Pigment Blue 60) with CAS number 81-77-6 from BASF SE, 67065 Ludwigshafen, Germany. This colorant has a bulk volume of 7 l/kg, a pH of 6-9 and a specific surface area of 40 m.sup.2/g.

[0242] Sicotan Yellow K1010:

[0243] Ni/Sb/Ti oxide with CAS number 8007-18-9 from BASF SE, Ludwigshafen, Germany.

[0244] Sicotan Yellow K2107:

[0245] Cr/Sb/Ti oxide with CAS number 68186-90-3 from BASF SE, Ludwigshafen, Germany.

[0246] Ultramarine Blue Nubix F-70:

[0247] Pigment Blue 29 with CAS number 057455-37-5 from Nubiola (Ferro Corp.; Mayfield Heights, Ohio, USA).

[0248] Triphenylphosphine:

[0249] Triphenylphosphine (TPP), Sigma-Aldrich, 82018 Taufkirchen, Germany.

[0250] Black Pearls 800:

[0251] Black Pearls® 800, CAS number 1333-86-4; particle size about 17 nm; from Cabot Corp.

[0252] Richnox B900:

[0253] Mixture of Richfos 168 (80% by weight) and Richox 1076 (20% by weight), Richfos 168 being tris(2,4-di-tert-butylphenyl) phosphite with CAS number 31570-04-4 and Richnox 1076 being octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; Rich Yu Chemical B.V., The Netherlands.

[0254] Tinuvin 326:

[0255] 2-(5-Chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol with CAS number 3896-11-5 from BASF SE, Ludwigshafen, Germany.

[0256] Tinuvin 329:

[0257] Tinuvin® 329; 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole with CAS number 3147-75-9 from BASF SE, Ludwigshafen, Germany.

[0258] TOF:

[0259] Triisooctyl phosphate (TOF; tris-2-ethylhexyl phosphate) with CAS number 78-42-2. Disflamoll TOF from Lanxess Deutschland GmbH.

[0260] Production of the Thermoplastic Polymer Compositions by Compounding:

[0261] The additives were compounded with the amounts of components specified in the examples on a KraussMaffei Berstorff ZE25 twin-screw extruder at a barrel temperature of 260° C. or a melt temperature of 270° C. and at a speed of 100 rpm at a throughput of 10 kg/h. First of all, for better mixing, a powder mixture (10% by weight of powder mixture, based on the overall composition) containing the additives was made up here. This powder mixture was metered into the remaining polycarbonate in the course of compounding.

[0262] Production of the Test Specimens:

[0263] The pelletized material was dried at 120° C. under reduced pressure for 3 hours and then processed on an Arburg 370 injection molding machine with a 25 injection unit at a melting temperature of 300° C. and a mold temperature of 90° C. to give color specimen plaques of dimensions 60 mm×40 mm×Z mm, where Z is 3.2 mm, 4.0 mm or 5.0 mm.

[0264] Painting of the Test Specimens (“UV Paint System”):

[0265] The primer used was the product SHP470FT (Momentive Performance Materials Inc. Wilton, Conn. USA). The protective varnish used was the product AS 4700 (Momentive Performance Materials Inc. Wilton, Conn. USA).

[0266] Coating was effected in a coating chamber with a controlled atmosphere under the respective stipulations of the coating manufacturer, at 23 to 25° C. and at 40% to 48% relative humidity.

[0267] The test specimens were cleaned using so-called iso wipes (LymSat® from LymTech Scientific; saturated with 70% isopropanol and 30% deionized water), rinsed off with isopropanol, dried in air for 30 minutes and blown with ionized air.

[0268] The test specimens were coated by hand by the flow-coating method. This involved pouring the primer solution over the sheet in the longitudinal direction starting from the upper edge of the small part, while the starting point of the primer on the sheet was simultaneously guided from left to right across the width of the sheet. The primed sheet was ventilated until dust-dry hanging vertically on a clip and cured in an air circulation oven according to the respective manufacturer's stipulations (ventilated at room temperature for 30 minutes and cured at 125° C. for 30 minutes). Cooling to room temperature was followed by coating of the primed surface with AS 4700. Ventilation until dust-dry was followed by curing at 130° C. in an air circulation oven for 60 min.

[0269] The primer layer thickness and the thickness of the topcoat can affect the weathering properties.

[0270] The primer layer thickness for the examples that follow was in the range of 1.2-4.0 μm, and the thickness of the topcoat between 4.0 and 8.0 μm.

TABLE-US-00001 TABLE 1 Comparative example 1-1. Uncoated test specimen. Starting material % by weight PC1, containing UV absorber, demolding agent 99.440 Macrolex Yellow G Gran. 0.005 Bayferrox 110 M 0.100 Macrolex Red EG 0.300 Colorant 12a/b [specialty] 0.005 Kronos 2230 0.150

TABLE-US-00002 TABLE 2 Comparative example 1-2. Uncoated test specimen. Starting material % by weight PC2 95.00 PC3 4.29 Macrolex Yellow G 0.005 Bayferrox 110 M 0.100 Macrolex Red EG 0.300 Colorant 12a/b 0.005 Altiris 550 0.300

TABLE-US-00003 TABLE 3 Comparative example 1-3. Uncoated test specimen. Starting material % by weight PC2 95.00 PC3 4.29 Macrolex Yellow G 0.005 Bayferrox 110 M 0.100 Macrolex Red EG 0.300 Colorant 12a/b 0.005 Altiris 800 0.300

TABLE-US-00004 TABLE 4 Comparative example 1-4. Uncoated test specimen. Starting material % by weight PC2 95.00 PC3 4.29 Macrolex Yellow G 0.005 Bayferrox 110 M 0.100 Macrolex Red EG 0.300 Colorant 12a/b 0.005 Kronos 2230 titanium dioxide 0.150 Altiris 550 0.150

TABLE-US-00005 TABLE 5 Uncoated test specimens 1-1 to 1-4 before and after weathering. Ex. Y.I. Gloss 60° 1-1 0 h 103.4 103 1-1 1100 h 90.6 28 1-2 0 h 106.1 102.3 1-2 1100 h 100.2 8 1-3 0 h 101.1 102 1-3 1100 h 97.4 11 1-4 0 h 109 102.4 1-4 1100 h 97.5 5

[0271] It is found that, after weathering, all samples, the uncoated test specimens 1-1 to 1-4, have a severe loss of gloss. The differences in the loss of gloss between the samples tend to be small. Of all the samples, example A with titanium dioxide of the Kronos 2230 type still shows the greatest gloss value after weathering. The color is likewise adversely affected, which is documented by the change in Y.I. (measured in reflection). Mixtures of various titanium dioxide types (example 4) show a severe loss of gloss and a color shift. It is barely possible to visually distinguish samples 1-1 to 1-4. In spite of different titanium dioxide types, there are visually no significant differences between the colors of the samples after weathering.

TABLE-US-00006 TABLE 6 Comparative example 2-1; substrate layer coated with UV paint system. Red color impression. Starting material % by weight PC4 99.435 Kronos 2230 0.100 Sicotan Yellow K2107 0.030 Heucodur Blue 2R 0.022 Macrolex Red EG 0.350 Bayferrox 110 M 0.0630

TABLE-US-00007 TABLE 7 Comparative example 2-2; substrate layer coated with UV paint system. Brown color impression. Starting material % by weight PC4 99.2055 Oracet Yellow 180 (Oracet Yellow GHS) 0.0145 Sicotan Yellow K2107 0.2200 Colortherm Red 130M 0.2850 Elftex 570 pearls [specialty] 0.1400 Kronos 2230 0.1350

TABLE-US-00008 TABLE 8 Comparative example 2-3; substrate layer coated with UV paint system. Green color impression. Starting material % by weight PC4 98.9845 Macrolex Yellow 6G [specialty] 0.0125 Sicotan Yellow K2107 0.3500 Heliogen Green K8730 0.3470 Lamp Black 101 0.1060 Kronos 2230 0.2000

TABLE-US-00009 TABLE 9 Comparative example 2-4; substrate layer coated with UV paint system. Yellow color impression. Starting material % by weight PC4 98.875 Macrolex Yellow 6G [specialty] 0.124 Sicotan Yellow K2107 0.021 Kronos 2230 0.98

TABLE-US-00010 TABLE 10 Comparative example 2-5; substrate layer coated with UV paint system. Blue color impression. Starting material % by weight PC4 99.26182 Sicotan Yellow K1010 0.10000 Ultramarine Blue Nubix F-70 0.23800 Heliogen Blue K7104 LW 0.16800 Heliogen Green K8730 0.00148 Lamp Black 101 0.00070 Kronos 2230 0.13000 Triphenylphosphine (TPP) 0.10000

TABLE-US-00011 TABLE 11 Test specimens 2-1 to 2-5 before and after XeWom 0.75 W weathering L* a* b* L* a* b* 0 h 0 h 0 h 3000 h 3000 h 3000 h Δ L* Δ a* Δ b* C. 2-1 34.21 36.85 17.33 35.97 34.59 14.62 1.76 2.26 2.71 C. 2-2 26.40 2.02 1.67 26.94 1.50 0.95 0.54 0.52 0.72 C. 2-3 30.54 −12.44 2.45 31.44 −12.17 1.01 0.90 0.27 1.44 C. 2-4 90.02 −9.35 81.89 90.86 −8.55 65.88 0.84 0.80 16.09 C. 2-5 34.73 −5.48 −29.34 36.07 −6.74 −28.74 1.34 1.26 0.6 C.: here and hereinafter = comparative example Visual impression: C. 2-1: loss of gloss C. 2-2: loss of gloss C. 2-3: loss of gloss C. 2-4: loss of gloss C. 2-5: loss of gloss; streaks

[0272] Surprisingly, color formulations for red, green, blue, yellow and brown hues all show unstable weathering characteristics, even though a titanium dioxide pigment optimized for polycarbonate, Kronos 2230, was used. Moreover, a UV scratch-resistant coating had also been applied to the specimens. For all specimen plaques, however, after weathering, a loss of gloss or brilliance was visually apparent. This loss of brilliance is in spite of coating with a UV-containing paint system. Example 2-2 shows a smaller variance in color with regard to the Lab values. This is probably attributable to a small content of organic colorant. It can be assumed that inorganic colorants will have much higher color stability.

TABLE-US-00012 TABLE 12 Comparative examples 3-1 to 3-5. Substrate layer coated with UV paint system. C. 3-1 C. 3-2 C. 3-3 C. 3-4 C. 3-5 Yellow Red Green Blue Brown % by % by % by % by % by Starting materials weight weight weight weight weight Makrolon ® AG2677 98.3405 99.44 93.905 99.4035 99.288 Kronos 2230 1.47 0.15 0.200 0.29 0.22 Bayferrox 110M 0.100 0.29 Red EG 0.300 Macrolex Yellow 6G 0.181 Oracet Yellow 180 0.0085 Macrolex Yellow G 0.005 0.005 0.001 0.005 Colorant 12a/b 0.005 0.0055 Sicotan Yellow K2107 0.43 Heliogen Green K8730 0.35 Lamp Black 101 0.11 Heliogen Blue K7104 0.25 TPP 0.05 Sicotan Yellow K2011 0.077 Black Pearls 800 0.12

TABLE-US-00013 TABLE 13 Comparative examples 3-1 to 3-5 before and after weathering. Gloss Gloss L* a* b* 60° L* a* b* 60° 0 h 2600 h C. 3-1 90.5 −9.6 82.1 81.5 91.9 −8.9 65.6 79.8 Yellow C. 3-2 34.9 36.1 17 79 36.7 34.1 13.4 76.2 Red C. 3-3 31.2 −12.7 2.5 78 32.5 −12 1.43 76.3 Green C. 3-4 26.5 1.9 1.7 78 27.2 1.46 1.1 76.8 Brown Visual impression: C. 3-1 Yellow: distinct loss of gloss C. 3-2 Red: distinct loss of gloss C. 3-3 Green: distinct loss of gloss C. 3-4 Brown: moderate loss of gloss

[0273] Further compositions for a green, red, yellow and brown color setup are detailed in comparative examples 3-1 to 3-4. As in comparative examples 2-1 to 2-5, the compositions are unstable to weathering.

TABLE-US-00014 TABLE 14 Comparative examples 4-1 to 4-5. Test specimens with UV absorber and triisooctyl phosphate in the substrate layer. Substrate layer coated with UV paint system. C. 4-1 C. 4-2 C. 4-3 C. 4-4 C. 4-5 Yellow Red Green Blue Brown % by % by % by % by % by Starting material weight weight weight weight weight Makrolon ® AG2677 98.1305 99.23 98.795 99.1935 99.078 Kronos 2230 1.47 0.15 0.200 0.29 0.22 Bayferrox 110M 0.100 0.29 Red EG 0.300 Macrolex Yellow 0.181 6G Oracet Yellow 180 0.0085 Macrolex Yellow G 0.005 0.005 0.001 0.005 Colorant 12a/b 0.005 0.0055 Sicotan Yellow 0.43 K2107 Heliogen Green 0.35 K8730 Lamp Black 101 0.11 Heliogen Blue 0.25 K7104 TPP 0.05 Sicotan Yellow 0.077 K2011 Black Pearls 800 0.12 TOF 0.01 0.01 0.01 0.01 0.01 Tinuvin 329 0.2 0.2 0.2 0.2 0.2

TABLE-US-00015 TABLE 15 Comparative examples 4-1 to 4-5 before and after weathering. Gloss Gloss L* a* b* 60° L* a* b* 60° 0 h 2600 h C. 4-1 90.5 −9.6 82.7 80 91.9 −9.0 65.1 79.1 Yellow C. 4-2 34.9 36.1 17.2 78 36.7 34.3 13.5 76.8 Red C. 4-3 31.3 −13.7 2.5 77.8 32.0 −13 1.7 76.7 Green C. 4-4 34.8 −6.5 −29 77.9 35.2 −5.4 −30 77 Blue C. 4-5 26.5 1.71 1.7 77.9 27.2 1.26 0.77 76.6 Brown Visual impression: C. 4-1: distinct loss of gloss C. 4-2: distinct loss of gloss (color looks very dull) C. 4-3: distinct loss of gloss (color looks very dull) C. 4-4: no loss of gloss (color looks colorful) C. 4-5: moderate loss of gloss (color looks dull)

[0274] It is known that titanium dioxide-containing pigments interact with UV radiation and hence have high photoactivity. However, a relatively high UV absorber content in the substrate layer has, surprisingly, no influence on weathering stability in the case of Kronos 2230 titanium dioxide pigment optimized for polycarbonate.

TABLE-US-00016 TABLE 16 Comparative examples 5-1 to 5-4. Substrate layer coated with UV paint system. C. 5-4 C. 5-1 C. 5-2 C. 5-3 Red Red Yellow Blue w/o TiO.sub.2 % by % by % by % by Starting material weight weight weight weight PC1 95.00 95.00 95.00 95.00 PC3 4.437 3.86 4.6693 4.398 Kronos 2230 0.1 1.0 0.13 Bayferrox 110M 0.063 0.2 Red EG 0.4 0.35 Yellow 3G 0.14 Lamp Black 101 0.0007 Paliogen Blue 6385 0.2 Heucodur Blue 2R 0.022 Sicotan Yellow 0.03 K2107

TABLE-US-00017 TABLE 17 Comparative examples 5-1 to 5-4 before and after weathering. Gloss Gloss L* a* b* 60° L* a* b* 60° 0 h 2600 h C. 5-1 33.5 37.2 16.9 77.7 34.6 36.3 14.8 76.8 Red C. 5-2 87.1 −6.2 68.4 81 87.9 −5.1 60.8 79.2 Yellow C. 5-3 29.3 5.79 −20.5 78 29.6 4.37 −18.4 77 Blue C. 5-4 30.9 29.5 14.8 80 31.4 29.1 14.4 76.3 Red w/o TiO.sub.2 Visual impression: C. 5-1: distinct loss of gloss C. 5-2: distinct loss of gloss C. 5-3: little loss of gloss C. 5-4: no loss of gloss; dull color; not brilliant (relative to the 0 h value)

[0275] It is found that color formulations containing no titanium dioxide are very stable. No significant loss of gloss occurs after weathering. However, such hues have a dull color impression of low brilliance.

TABLE-US-00018 TABLE 18 Comparative examples 6-1 to 6-4. Higher colorant concentrations in the substrate layer. Substrate layer coated with UV paint system. C. 6-1 C. 6-2 C. 6-3 C. 6-4 % by % by % by % by Starting material weight weight weight weight PC1 95.0 95.0 95.0 95.0 PC3 3.87 3.15 3.50 4.0 Kronos 2230 0.2 0.4 0.5 Bayferrox 110M 0.126 0.25 Macrolex Red EG 0.7 1.0 Heucodur Blue 2R 0.044 0.1 Sicotan Yellow K2107 0.06 0.1 Sicotan Yellow K1010 1.0 Yellow 3G 0.5 0.5

TABLE-US-00019 TABLE 19 Comparative examples 6-1 to 6-4 before and after weathering. Gloss Gloss L* a* b* 60° L* a* b* 60° 0 h 2600 h C. 6-1 33.6 35.6 15.8 78 35.8 32.8 12.9 77.2 C. 6-2 34.2 35.4 15.8 78 38.8 29.4 11.6 77.1 C. 6-3 78.3 6.0 84.5 79 79.5 6.6 82.7 78.3 C. 6-4 73.8 16.1 74.9 79.3 74.4 16.4 70.3 78.2 Visual color impression: C. 6-1: loss of gloss C. 6-2: loss of gloss C. 6-3: no loss of gloss C. 6-4: no loss of gloss

[0276] It is found that compositions containing no titanium dioxide (C. 6-3) are very stable to weathering. However, such hues have a dull color impression of low brilliance. Since titanium dioxide breaks down organic colorants as a result of the photoactivity discussed, the person skilled in the art would have expected an increase in the color concentration of organic colorants in the compositions to contribute to elevated stability. However, this is surprisingly not the case (C. 6-1, C. 6-2).

TABLE-US-00020 TABLE 20 Inventive examples 7-1 to 7-4. Different titanium dioxide (Altiris 550, 800) in the substrate layer. Substrate layer coated with UV paint system. Ex. 7-1 Ex. 7-2 Ex. 7-3 Ex. 7-4 Inv. Inv. Inv. Inv. % by % by % by % by Starting material weight weight weight weight PC2 95.000 95.000 95.000 95.000 PC3 4.290 4.290 3.740 3.740 Macrolex Yellow G 0.005 0.005 0.005 0.005 Bayferrox 110 M 0.100 0.100 0.100 0.100 Macrolex Red EG 0.300 0.300 0.300 0.300 Colorant 12a/b 0.005 0.005 0.005 0.005 Altiris 550 0.300 0.300 Altiris 800 0.300 0.300 Tinuvin 326 0.500 0.500 Richnox B900 0.050 0.050

TABLE-US-00021 TABLE 21 Examples 7-1 to 7-4 before and after weathering. L* a* b* L* a* b* 0 h 0 h 0 h 2750 h 2750 h 2750 h Δ L* Δ a* Δ b* Ex. 7-1 Inv. 36.06 35.68 18.94 36.87 35.15 17.49 0.81 0.53 1.45 Ex. 7-2 Inv. 34.38 33.78 17.66 35.08 33.59 16.41 0.70 0.19 1.25 Ex. 7-3 Inv. 35.29 35.39 18.11 36.00 35.05 16.85 0.71 0.34 1.26 Ex. 7-4 Inv. 33.88 33.70 16.88 34.41 33.65 16.11 0.53 0.05 0.77 In all inventive examples, the compositions have light transmittance of <0.5% in the range from 380 to 780 nm, determined at a sheet thickness of 4 mm to DIN ISO 13468-2: 2006 (D65, 10°). Visual impression: Inv. ex. 7-1: no loss of gloss Inv. ex. 7-2: no loss of gloss Comp. ex. 6-3: distinct loss of gloss Comp. ex. 6-4: distinct loss of gloss Inv. ex. 7-3: no loss of gloss Inv. ex. 7-4: no loss of gloss

[0277] Since red formulations showed the greatest loss of gloss after weathering, red formulations were selected as the basis for these further experiments. Compositions 7-1 to 7-4 together with a UV paint system as coating completely surprisingly result in a weathering-stable multilayer article. The combination of titanium dioxide for use in accordance with the invention having a specific minimum particle size and coating composition comprising Kronos 2230, by contrast, does not lead to weathering-stable multilayer articles. This could not be assumed from the small or zero differences in the case of uncoated test specimens. The titanium dioxide for use in accordance with the invention with the greatest particle size (D.sub.50) gives the most stable compositions for the multilayer articles of the invention.

[0278] It is also apparent (C. 7-3, C. 7-4) that UV absorbers in combination with the titanium dioxide grades to be used in accordance with the invention display a positive effect. This was likewise not to be expected in the light of the comparative examples with elevated UV absorber content.

TABLE-US-00022 TABLE 22 Melt stability of compositions with different titanium dioxide grades. Compositions 8-1 to 8-3. Ex. 8-1 Ex. 8-2 Ex. 8-3 Starting material % by weight % by weight % by weight PC2 95.0 95.0 95.0 PC3 4.5 4.5 4.5 Altiris 550 0.5 Altiris 800 0.5 Kronos 2230 0.5

TABLE-US-00023 TABLE 23 Melt stability of compositions 8-1 to 8-3. Ex. 8-1 Ex. 8-2 Ex. 8-3 MVR 300° C.; 5 min 7.4 6.8 6.9 MVR 300° C.; 20 min 7.7 7.5 7.5 MVR 300° C.; 30 min 8.0 7.9 7.8

[0279] It has been shown that, surprisingly, compositions containing a non-polycarbonate-optimized titanium dioxide pigment (ex. 8-1 and 8-2) do not show significantly lower melt stability than compositions containing a polycarbonate-optimized titanium dioxide grade (Kronos 2230, ex. 8-3).