Multi-layer body made of polycarbonate with high weathering resistance

Abstract

Disclosed is a multi-layer body with high weathering resistance comprising (a) a substrate layer containing at least one thermoplastic polymer (b) one cover layer on at least one side of the substrate layer, characterized in that the substrate layer further contains: (a1) at 0.02 wt. % to 0.2 wt %, at least one colorant on the basis of anthraquinone of structure (1) or (2) with structure (1), R1 and R2 standing, independently of each other, for H, OH, OR5 NH2 and NHR5, R5 being selected from alkyl, cycloalkyl, phenyl and substituted and annulated phenyls, and R3 standing for H, alkyl, alkoxy, and R4 standing for H, OH and p-methylphenyl-NH—; and with structure (2): (a2) at 0.01 wt % to 1.00 wt. %, one or a plurality of demolders, and the cover layer consisting of a coating on the basis of polysiloxane or on the basis of polyacrylate or on the basis of polyurethane acrylate, containing at least one UV-absorber and having a layer thickness of 2-15 [mu]m.

Claims

1. A multilayer structure having high weathering stability comprising a) a substrate layer having a light transmission (ISO 13468-2) of less than 1.0% and containing at least one thermoplastic polymer, b) an outer layer at least on one side of the substrate layer, wherein the substrate layer further comprises: a1) 0.02% by weight to 0.2% by weight of at least one anthraquinone-based colorant of the structure (1) or (2) with structure (1) ##STR00018## where R.sub.1 and R.sub.2 are each independently H, OH, OR.sup.5, NH.sub.2 or NHR.sup.5, where R.sup.5 is alkyl, cycloalkyl, phenyl or substituted and fused phenyls and where R.sub.3 is H, alkyl or alkoxy and where R.sub.4 is H, OH or p-methylphenyl-NH—; and with structure (2): ##STR00019## a2) 0.01% by weight to 1.00% by weight of one or more demolding agents, and the outer layer consists of a polysiloxane-based or polyacrylate-based or polyurethane acrylate-based coating and contains at least one UV absorber and has a layer thickness of 2-15 μm.

2. The multilayer structure as claimed in claim 1, wherein the dye a1) is selected from the group consisting of structures 1A to 1H ##STR00020## ##STR00021##

3. The multilayer structure as claimed in claim 1, wherein the substrate layer a) further comprises at least one dyes selected from the group consisting of structures (3) to (7) ##STR00022## where R3 is halogen, where n is an integer of 0-4 and, ##STR00023## R5-R20 radicals are each independently hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, thexyl, fluorine, chlorine, bromine, sulfone or CN, M is aluminium, cobalt, iron, zinc, copper or manganese, ##STR00024## where R1 and R2 are each independently a linear or branched alkyl radical or halogen, n is a natural number from 0 to 4 ##STR00025##

4. The multilayer structure as claimed in claim 2, wherein the substrate layer comprises one dye of the structure (1C) and one dye selected from the group consisting of structures (1H), (1G), (1D) and (2).

5. The multilayer structure as claimed in claim 1, wherein the substrate layer is free of carbon black and perinone-based dyes.

6. The multilayer structure as claimed in claim 1, wherein the substrate layer further comprises the following components: a3) at least one thermal stabilizer in a proportion of 0.00% by weight-0.20% by weight, a4) at least one processing stabilizer in a positive proportion of less than 0.05% by weight, a5) at least one UV absorber in a proportion of 0.0% to 20.0% by weight, and a6) at least one further additive in a proportion of 0.0% by weight to 5.0% by weight.

7. The multilayer structure as claimed in claim 1, wherein the substrate layer further comprises the following components: a3) at least one thermal stabilizer in a proportion of 0.01% by weight-0.10% by weight, a4) at least one processing stabilizer in a proportion of 0.00005% by weight to 0.05000% by weight, a5) at least one UV absorber in a proportion of 0.10% to 1.00% by weight, and a6) at least one further additive in a proportion of 0.01% by weight to 1.00% by weight.

8. The multilayer structure as claimed in claim 1, wherein the thermoplastic polymer in the substrate layer is a polycarbonate or a polycarbonate blend containing vinyl (co)polymers or polyesters.

9. The multilayer structure as claimed in claim 6, wherein component a4) is triisooctyl phosphate.

10. The multilayer structure as claimed in claim 1, wherein the outer layer is a polysiloxane-based coating.

11. The multilayer structure as claimed in claim 1, wherein the outer layer has a thickness of 4.0 to 12.0 μm.

12. The multilayer structure as claimed in claim 1, wherein an outer layer is disposed on both sides of the substrate layer.

13. The multilayer structure as claimed in claim 1, wherein a primer layer is disposed between the outer layer and substrate layer.

14. The multilayer structure as claimed in claim 13, wherein the primer layer has a thickness of 0.3 μm to 8.0 μm.

15. A process for producing a multilayer structure, wherein the process comprises the following steps: producing a substrate material comprising polycarbonate having a light transmission (ISO 13468-2) of less than 1.0% and a melt volume flow rate (MVR) of 7 cm.sup.3/10 min to 25 cm.sup.3/10 min comprising a1) 0.02% by weight to 0.2% by weight of at least one anthraquinone-based colorant of the structure (1) or (2) with structure (1) ##STR00026## where R.sub.1 and R.sub.2 are each independently H, OH, OR.sup.5, NH.sub.2 or NHR.sup.5, where R.sup.5 is alkyl, cycloalkyl, phenyl or substituted and fused phenyls and where R.sub.3 is H, alkyl or alkoxy and where R.sub.4 is H, OH or p-methylphenyl-NH—; and with structure (2): ##STR00027## a2) 0.01% by weight to 1.00% by weight of one or more demolding agents and optionally components a3) to a6); a3) at least one thermal stabilizer, a4) at least one processing stabilizer, a5) at least one UV absorber, a6) at least one further additive producing a molding in a specific framework geometry at high mold temperatures; coating the molding in a flow-coating process with a primer solution comprising a) organic binder material which enables adhesion between PC and a polysiloxane-based coating material, and b) at least one UV absorber, c) an alcohol-based solvent, venting the molding at room temperature for 10-60 min and curing at 100-135° C. for 5 min to 60 min., coating the molding with a siloxane coating material in a flow-coating process comprising a) organosilicon compounds of the formula R.sub.nSiX.sub.4-n (with n from 1 to 4), where R represents aliphatic C1 to C10 radicals and aryl radicals, and X is H, aliphatic C1 to C10 radicals and aryl radicals, or partial condensates thereof, b) at least one finely divided inorganic compound, c) an alcohol-based solvent, d) at least one UV absorber; and venting the molding at room temperature for 10-60 min and curing at 100-140° C. for 10 min to 120 min.

Description

EXAMPLES

(1) The invention is described in detail hereinafter with reference to working examples, the determination methods described here being employed for all the corresponding parameters in the present invention, unless stated otherwise.

(2) Melt Volume Flow Rate:

(3) Melt volume flow rate (MVR) is determined to ISO 1133 (at 300° C.; 1.2 kg).

(4) Light transmission (Ty):

(5) The transmission measurements were conducted to ISO 13468-2 on a Perkin Elmer Lambda 900 spectrophotometer with photometer sphere (i.e. determination of total transmission by measurement of diffuse transmission and direct transmission).

(6) Weathering:

(7) Artificial weathering with xenon exposure is conducted to standard ASTM G 155 in an Atlas CI 5000 xenon weatherometer. The UV filters used were two borosilicate filters. The exposure intensity is 0.75 W/m.sup.2/nm at 340 nm. The black standard temperature is 80° C., the sample space temperature is 40° C. The samples are sprayed every 120 min for 18 min, with the exposure remaining switched on during the spraying phase as well. The aforementioned weathering method is called Xe-Wom 0.75W hereinafter.

(8) Materials for Production of the Test Specimens:

(9) Linear bisphenol A polycarbonate having end groups based on phenol, having an MVR of 12.5 cm.sup.3/10 min, measured at 300° C. and load 1.2 kg to ISO 1033), containing 0.025% by weight of triphenylphosphine (CAS 603-35-0) and 0.40% by weight of pentaerythritol tetrastearate (CAS 115-83-3), referred to hereinafter as PC1. For the comparative examples, the nanoscale carbon black used—in the masterbatch as well—is Black Pearls® 800 (CAS No. 1333-86-4) (particle size about 17 nm) from Cabot Corp. For the inventive example, the colorant used is of the structure (1H) Macrolex Violet 3R from Lanxess AG. For the inventive example, the colorant used is of the structure (1C) Macrolex Green 5B from Lanxess AG.
Painting of the Test Specimens:

(10) The primer used is the product SHP470FT (Momentive Performance Materials Inc. Wilton, Conn. USA). The protective varnish used is the product AS 4700 (Momentive Performance Materials Inc. Wilton, Conn. USA).

(11) The coating was effected in a climate-controlled coating chamber following the respective instructions from the coating material manufacturer at 23 to 25° C. and 40% to 48% relative humidity.

(12) The test specimens were cleaned with Iso wipes (LymSat® from LymTech Scientific; saturated with 70% isopropanol and 30% deionized water), rinsed with isopropanol, dried under air for 30 min and blown dry with ionized air.

(13) The test specimens were coated manually by the flow-coating process. This involves pouring the primer solution, proceeding from the upper edge of the small part, over the sheet in the longitudinal direction, while, at the same time, the application point of the primer to the sheet is moved from left to right over the sheet width. The primed sheet was vented until it was dust-dry and cured in an air circulation oven while hanging vertically, suspended from a clamp, according to the respective manufacturer's instructions (vented at room temperature for 30 minutes and cured at 125° C. for 30 minutes). After cooling to room temperature, the primed area was coated with AS 4700. Venting to dust-dryness was followed by curing at 130° C. in an air circulation oven for 60 min.

(14) The primer layer thickness and the thickness of the topcoat can affect the weathering properties.

(15) In order to achieve an adequate and comparable barrier action against weathering, the primer layer thickness for the examples which follow is to be in the range of 1.2-4.0 μm and the thickness of the topcoat between 4.0 and 8.0 μm.

(16) Production of Thermoplastic Polymer Compositions by Compounding:

(17) The polymer composition was compounded with the amounts of components specified in the examples on a KraussMaffei Berstorff ZE25 twin-screw extruder at a casing temperature of 260° C. and a melt temperature of 270° C. and a speed of 100 rpm at a throughput of 10 kg/h.

(18) The pellets are dried at 120° C. under reduced pressure for 3 hours and then processed on an Arburg 370 injection molding machine having a 25 injector unit at a melt temperature of 300° C. and a mold temperature of 90° C. to give color specimen sheets having dimensions 60 mm×40 mm×3.2 mm.

Example 1 (Inventive)

(19) PC1 is compounded as described above with 0.1% by weight of Macrolex Violet 3R and 0.1% by weight of Macrolex Green 5B. The above-described color specimen sheets are produced, and painted and weathered as described.

Example 2 (Comparative)

(20) PC1 is compounded as described above with 0.08% by weight of Black Pearls. The above-described color specimen sheets are produced, and painted and weathered as described.

Example 3 (Comparative)

(21) PC1 is compounded as described above with 0.16% by weight of Black Pearls. The above-described color specimen sheets are produced, and painted and weathered as described.

(22) TABLE-US-00001 Example 1 Example 2 Example 3 (inventive) (comparative) (comparative) Light transmission 0% 0% 0% Finding after 5000 h No defects No defects Cracks; Xe-WOM 0.75 W commencement of weathering delamination of the paint layer Finding after 6000 h No defects Large-area Large-area Xe-WOM 0.75 W delamination of delamination of the weathering the paint layer paint layer

(23) It is apparent that the inventive multilayer structure has a much higher weathering resistance than multilayer structures corresponding to the prior art.