LAYERED COMPOSITE COMPRISING POLYCARBONATE AND A POLYCARBONATE BLEND FOR IMPROVED PAINTABILITY

Abstract

The present invention relates to a layered composite comprising a poly carbonate-based matrix, possibly containing fibres, and an outer layer of special poly carbonate-polyester blends, and also to a layered composite such as that described above and provided with painting on that side of its outer layer which is facing away from the matrix, to a method for producing these composites and also to their use for the production for example of automobile add-on parts.

Claims

1.-14. (canceled)

15. A layer composite comprising a substrate layer S and a top layer D at least partially joined to the substrate layer S, wherein the material of the substrate layer S comprises a first thermoplastic polymer and the material of the top layer D likewise comprises the first thermoplastic polymer, wherein the first thermoplastic polymer is an aromatic polycarbonate and the material of the top layer D comprises the first thermoplastic polymer as a blend with a polyester component P, wherein i) the proportion of the polyester component P is ≥2% by weight, based on the total weight of the material of the top layer D, and wherein the polyester component P comprises at least one polycycloalkylene terephthalate, or ii) the proportion of the polyester component P is ≥10% by weight, based on the total weight of the material of the top layer D, and wherein the polyester component P comprises at least one polyalkylene terephthalate, or iii) the proportion of the polyester component P is ≥20% by weight, based on the total weight of the material of the top layer D, and wherein the polyester component P comprises at least one polyalkylene naphthalate, or iv) the proportion of the polyester component P is ≥2% by weight, based on the total weight of the material of the top layer D, and wherein the polyester component P comprises a mixture of at least 2 of the following components: at least one polycycloalkylene terephthalate, at least one polyalkylene terephthalate, at least one polyalkylene naphthalate.

16. The layer composite as claimed in claim 15, wherein disposed on the side of the top layer D facing away from the substrate layer S there is a paint layer L which is at least partially joined to the top layer D.

17. The layer composite as claimed in claim 15, wherein the substrate layer S comprises reinforcing fibers.

18. The layer composite as claimed in claim 17, wherein the substrate layer S comprises a plurality of plies of in each case unidirectionally aligned endless fibers and the endless fibers of one ply do not have the same orientation as endless fibers of directly adjacent plies.

19. The layer composite as claimed in claim 15, wherein the first thermoplastic polymer 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.

20. The layer composite as claimed in claim 15, wherein the material of the top layer D further contains an impact modifier.

21. The layer composite as claimed in claim 15, wherein the top layer D has a thickness ≤500 μm.

22. The layer composite as claimed in claim 16, wherein the paint layer L comprises at least one primer layer G, at least one basecoat layer B and at least one clearcoat layer K.

23. The layer composite as claimed in claim 22, wherein at least one of the layers comprised by the paint layer L is water-based.

24. A process for producing a layer composite, comprising the step of: I) joining a substrate layer S to a top layer D, wherein the material of the substrate layer S comprises a first thermoplastic polymer and the material of the top layer D likewise comprises the first thermoplastic polymer, wherein the first thermoplastic polymer is an aromatic polycarbonate and the material of the top layer D comprises the first thermoplastic polymer as a blend with a polyester component P, wherein i) the proportion of the polyester component P is ≥2% by weight, based on the total weight of the material of the top layer D, and wherein the polyester component P comprises at least one polycycloalkylene terephthalate, or ii) the proportion of the polyester component P is ≥10% by weight, based on the total weight of the material of the top layer D, and wherein the polyester component P comprises at least one polyalkylene terephthalate, or iii) the proportion of the polyester component P is ≥20% by weight, based on the total weight of the material of the top layer D, and wherein the polyester component P comprises at least one polyalkylene naphthalate, or iv) the proportion of the polyester component P is ≥2% by weight, based on the total weight of the material of the top layer D, and wherein the polyester component P comprises a mixture of at least 2 of the following components: at least one polycycloalkylene terephthalate, at least one polyalkylene terephthalate, at least one polyalkylene naphthalate.

25. The process as claimed in claim 24, further comprising the step of: II) applying at least one paint layer L to the side of the top layer D facing away from the substrate layer S in the layer composite obtained according to step I).

26. The process as claimed in claim 24, wherein the substrate layer S comprises reinforcing fibers.

27. The process as claimed in claim 25, wherein the paint layer L comprises at least one primer layer G, at least one basecoat layer B and at least one clearcoat layer K and wherein optionally at least one of the layers comprised by the paint layer L is water-based.

28. An automotive exterior components comprising a layer composite as claimed in claim 15.

Description

EXAMPLES

[0148] The present invention is elucidated in detail by the examples which follow, but without being limited thereto.

[0149] Production of the Substrate S:

[0150] For the experiments sheets of a composite material made of polycarbonate and carbon fiber (referred to hereinbelow as composite) having dimensions of 350×350 mm.sup.2 were used as the substrate layer. The composites were produced by Covestro Thermplast Composite GmbH (CTC) from 8 plies of UD tape, wherein the UD tapes themselves were constructed from 40-45% by volume of unidirectionally oriented carbon fiber of the type Mitsubishi TRH-50 60M and 60-55% by volume of polycarbonate matrix (Makrolon® 3107 in color 901510). A general description of production may be found for example in WO 2018/007335 A1.

[0151] Based on the angular orientation of the carbon fibers in the individual UD tape plies the ply construction was selected such that quasi-isotropic reinforcement of the composite was achieved (0°/45°/−45°/90°/90°/−45°/45°/0°).

[0152] Production of the Top Layer D:

[0153] Thermoplastic molding compounds containing the components A to E with the formulations reported in table 1 were produced on a ZSK25 twin-screw extruder from Coperion, Werner and Pfleiderer (Germany) at melt temperatures of 250° C. to 300° C. The obtained pellet materials were subsequently used to extrude films having a thickness of about 100 μm. To this end the corresponding material was after predrying (4 h, 85-90° C.) melted in the extruder (at about 50 rpm, melt temperature 265° C. (entries 1-16 in table 1) and 300° C. (entry 17 in table 1)), and extruded onto rollers via a 450 mm slot die.

[0154] Employed Components in the Top Layer D:

[0155] Component A: linear bisphenol A polycarbonate having an average molecular weight Mw of about 31 000 g/mol and a softening temperature (VST/B 120 according to ISO 306:2014-3) of 150° C. which contains no UV absorber. The melt volume flow rate (MVR) according to ISO 1133:2012-03 was 6.0 cm.sup.3/(10 min) at 300° C. and a 1.2 kg load.

[0156] Component B1: Polybutylene terephthalate (PBT) with a melt mass flow rate (MFR) of 9.0 g/10 min to 14.5 g/10 min measured according to DIN EN ISO 1133 at a temperature of 250° C. and with a load of 2.16 kg.

[0157] Component B2: Polyethylene terephthalate (PET) having an intrinsic viscosity of 0.623 dl/g. The specific viscosity is measured in dichloroacetic acid in a concentration of 1% by weight at 25° C. The intrinsic viscosity is calculated from the specific viscosity according to the following formula:

Intrinsic viscosity=specific viscosity.Math.0.0006907+0.063096

[0158] Component B3: Polyester based on terephthalic acid, cyclohexanedimethanol and 2,2,4,4-tetramethyl-1,3-cyclobutanediol having an inherent viscosity of 0.69-0.75 dl/g measured in a 60/40 mixture (% by wt/% by wt) of phenol/tetrachloroethane at 25° C. in a concentration of 0.5 g/100 ml.

[0159] Component B4: Polyethylene Naphthalate (PEN).

[0160] Component C: Impact modifier having core-shell morphology, a styrene-butadiene-rubber core and a grafted shell made of methyl methacrylate-styrene copolymer, a butadiene content of 68%-72% and a rubber particle size distribution between 130 nm and 160 nm.

[0161] Component D1: Talc having an average particle diameter d.sub.50 of 1.2 μm, measured using a sedigraph and having an Al.sub.2O.sub.3 content of 0.5% by weight.

[0162] Component D2: Irganox 1076, heat stabilizer, BASF SE

[0163] Component D3: Phosphorous acid H.sub.3PO.sub.3 as solid.

[0164] Component E: Pentaerythrityl tetrastearate as a lubricant/demolding agent.

[0165] The composites (substrate) were then laminated on both sides with the films to be examined (top layer D) on a static laboratory press (Joos LAP 100). A polished insert (“high-gloss stamp”) and an external release agent (Frekote®, Henckel) were used.

[0166] Production of the Paint Layer L

[0167] Substances Used for Producing the Primer, Basecoat and Clearcoat Layers:

[0168] Unless otherwise stated, the substances were employed without further purification or pretreatment.

[0169] Additol XL 250, Allnex Resins Germany GmbH, DE, anionic wetting and dispersion agent for pigments

[0170] Aerosil® R 972, Evonik Resource Efficiency GmbH, DE, fumed silica matting agent

[0171] Aquatix 8421, BYK Chemie GmbH, DE, rheology-modifying wax emulsion

[0172] Bayferrox® 318 M, Lanxess AG, DE, iron oxide pigment

[0173] Bayhydrol® U 2757, Covestro AG, DE, aliphatic, anionic, hydroxy-functional polyurethane dispersion based on a mixture of aromatic polyester diol and a polycarbonate diol, co-solvent-free. Binder for producing water-thinnable 2K-PUR paints, about 52% in water/N,N-dimethylethanolamine, hydroxy content about 1.8% (calculated) based on nonvolatile proportion (1 g/l h/125° C.) according to DIN EN ISO 3251, as per data sheet of 2016-09-13.

[0174] Bayhydrol® UH 2606, Covestro AG, DE, aliphatic, polycarbonate-containing anionic polyurethane dispersion, co-solvent-free. Binder for producing water-thinnable coatings for plastic substrates and wood-based materials, about 35% in water, neutralized with N-ethyldiisopropylamine (bound as salt) in a ratio of about 35:64:1, as per data sheet of 2016-09-13.

[0175] Bayhydrol® UA 2856 XP, Covestro AG, DE, aliphatic, acrylate-modified polyurethane dispersion binder for aqueous, air- and oven-drying basecoats for 2-layer vehicle painting, plastic painting, automotive repainting, industrial painting and for low-temperature-drying functional stone chip layers.

[0176] Viscosity <100 mPa s at 23° C. (ISO 3219/A.3), as per data sheet of 2016-03-03 Bayhydur® XP 2655, Covestro AG, DE, hydrophilic polyisocyanate based on trimers of hexamethylene diisocyanate, NCO content 20.8% (ISO 11909), viscosity 3500 mPa s at 23° C. (ISO 3219/A.3), as per data sheet of 2017-06-01.

[0177] Baysilone® Paint Additive OL 17, OMG Borchers, DE, polyether-modified polysiloxane (flow control additive)

[0178] Blanc fixe micro, Sachtleben Chemie GmbH, DE, filler

[0179] Borchigel® PW 25, OMG Borchers, DE, polyurethane thickener

[0180] Butyl acetate (n-butyl acetate), Azelis Deutschland GmbH, solvent

[0181] Butyl glycol (2-butoxyethanol), BASF SE, DE, solvent

[0182] Byk® 348, BYK Chemie GmbH, DE, silicone surfactant to improve substrate wetting

[0183] Desmodur® ultra N 3390, Covestro AG, DE, aliphatic polyisocyanate (trimer of hexamethylene diisocyanate). As a hardener component for lightfast polyurethane paint systems.

[0184] NCO content 19.6% (ISO 11909), viscosity 500 mPa s at 23° C. (ISO 3219/A.3), as per data sheet of 2018-11-14.

[0185] Desmodur® ultra N 3600, Covestro AG, DE, polyisocyanate based on trimers of hexamethylene diisocyanate, NCO content 23.0% (ISO 11909), viscosity 1200 mPa s at 23° C. (ISO 3219/A.3), as per data sheet of 2017-06-01.

[0186] Desmophen® 670 BA, Covestro AG, DE, low-branched, hydroxyl-containing polyester for producing weather-resistant elastic paints.

[0187] Viscosity 3000 mPa s at 23° C. (ISO 3219/A.3), as per data sheet of 2018-03-01

[0188] Diacetone alcohol (DAA), Acros Organics, solvent

[0189] Dibutyltin dilaurate, ISO-ELEKTRA—Elektrochemische Fabrik GmbH, catalyst

[0190] N,N-Dimethylethanolamine (DMEA), Sigma Aldrich Chemie, DE, neutralizing agent

[0191] Dispex® Ultra FA 4436, BASF SE, DE, dispersing aid

[0192] Finntalc® M-15 AW, Mondo Minerals BV, NL, talc

[0193] 1-Methoxy-2-propyl acetate (MPA), BASF SE, DE, solvent

[0194] R-KB-2, Sachtleben Chemie GmbH, DE, white pigment

[0195] Setalux® DA 365 BA/X, Allnex Resins Germany GmbH, DE, functional acrylate polymer-containing binder

[0196] Setaqua 6801, Allnex Belgium SA/NV, non-functional acrylate-containing copolymer

[0197] Solvent Naphtha 100 (heavy benzol), Azelis Deutschland GmbH, solvent

[0198] Stapa Hydrolan 2156 No. 55900/G Aluminium, Eckart GmbH, DE, aluminum pigment paste

[0199] Surfynol® 104 E, Evonik Resource Efficiency GmbH, DE, nonionic wetting, defoaming and dispersing aid

[0200] Tinuvin® 292 and Tinuvin® 1130, BASF SE, DE, UV stabilizers

[0201] Paint Formulations:

[0202] Primer (aqueous, two-component plastic primer PCO-0148-PS as per starting formulation published by Covestro Deutschland AG (2016-09-13 edition)): To produce component 1 first the binders were initially charged and then the further constituents weighed in in the reported sequence before the mixture was admixed with glass beads (2.85-3.45 mm) 1:1 (by volume) and then ground with a Lau Skandex BA-S20 laboratory shaker for 30 minutes. The glass beads were then removed by sieving. While stirring with a dissolver (dissolver disk 5 cm, 800 rpm) the thickener was then slowly added and the mixture stirred for a further 5 minutes. Component 1 was then adjusted with demineralized water to a cup efflux time in the 4 mm DIN cup of 25 to 30 s.

[0203] Shortly before application component 2 was incorporated while stirring with a paddle stiffer (5 min, 700 rpm) and the ready-to-use primer was applied within 30 minutes.

TABLE-US-00001 TABLE 1 2-Component primer for plastics % by wt Component 1 Binder: Bayhydrol ® U 2757 20.5 Bayhydrol ® UH 2606 30.4 Constituents: 0.4 Dispex ® Ultra FA 4436 0.3 Surfynol ® 104 E 0.2 Byk ® 348 7.4 R-KB-2 11.1 Blanc fixe micro 3.7 Finntalc ® M-15 AW 0.2 Bayferrox ® 318 M 0.6 Aerosil ® R 972 0.2 Thickener: Borchigel ® PW 25 0.2 Demineralized water 20.5 Component 2 Desmodur ® ultra N 3600/Bayhydur ® 4.5 XP 2655 (70:30), 75% in MPA

[0204] Water-based metallic basecoat (one-component water-based paint HEBE 4134/1 according to starting formulation published by Covestro Deutschland AG (2016-08-23 edition)):

[0205] First, the metallic paste (table 2, part 3) was prepared in a separate vessel. To this end all constituents in table 2, part 3 were mixed in the reported sequence while stirring with a propeller stiffer. The pH was then tested (target: pH 8.0-8.5) and, if necessary, adjusted with DMEA. After stirring for a further 30 minutes at about 10.5 m/s (maximum heating to 50° C.) the paste was ready to use.

[0206] For the metallic basecoat part 1 and part 2 from table 2 were mixed with a propeller stiffer at about 5.2 m/s. Part 3 was then added and incorporated for 30 minutes at about 10.5 m/s. Finally, part 4 was added and the mixture was stirred for a further 5 minutes at 5.2 m/s. Before application the pH of the paint was adjusted to 8.0-8.5 with DMEA. The cup efflux time was adjusted to 40 s according to DIN cup 4 mm with demineralized water and the paint was filtered off through a 56 μm sieve.

TABLE-US-00002 TABLE 2 Water-based metallic basecoat % by wt Part 1 (binder) Setaqua 6801, f.s. (Nuplex Resins bv, 26.66 Netherlands) 26.66 Bayhydrol ® UA 2856 XP 13.71 Bayhydrol ® UH 2606 13.71 Part 2 Demineralized water 8.00 Butylglycol 7.01 DMEA, 10% in water 3.94 Part 3 (metallic paste having following 12.59 composition) Butylglycol (41.88) Setaqua B E 270 (2.89) Additol XL 250 (4.36) Stapa Hydrolan 2156 No. 55900/ (50.64) G Aluminium DMEA (0.23) Part 4 Aquatix 8421 4.48 Demineralized water 9.90

[0207] Clearcoat (solvent-based clearcoat RR 4822 according to starting formulation published by Covestro Deutschland AG (2015-09-01 edition):

[0208] To produce component 1 initially the binders were introduced. While stirring with a dissolver (dissolver disk 5 cm, 800 rpm) all further constituents in table 3, part 1 were added in the reported sequence and the mixture stirred for a further 5-10 minutes.

[0209] Shortly before application component 2 was incorporated while stirring with a paddle stirrer (5 min, 700 rpm) and the ready-to-use clearcoat was applied within 30 minutes.

TABLE-US-00003 TABLE 3 Clearcoat % by wt Part 1 Desmophen ® 670 BA 19.4 Setalux ® DA 365 BA/X 23.8 Baysilone ® Paint Additive OL 17, 0.5 10% in butyl acetate Dibutyltin dilaurate, 1% in butyl acetate 1.0 Tinuvin ® 292, 10% in MPA 1.0 Tinuvin ® 1130, 10% in MPA 4.9 1-Methoxy-2-propyl acetate (MPA) 2.5 Solvent Naphtha 100 11.1 Diacetone alcohol (DAA) 11.1 Part 2 5.5 Desmodur ® ultra N 3390 20.1

[0210] Painting of the Substrate-Top Layer Laminates

[0211] The procedure for producing the paint formulations and subsequent painting of the substrate layer-top layer laminates is described, inter alia, in the European patent application with application Ser. No. 18/213,389.2 still unpublished at the date of filing of the present invention. First, the aqueous, two-component plastic primer was prepared as described above and applied over the entire surface with a Satajet RP gravity spray gun, 1.3 mm, air pressure 2.1 bar, in 1 cross-pass to obtain a (dry) layer thickness of 20-25 m. After application, the primer was dried for 10 min at room temperature and for 30 min at 80° C. in a forced circulation oven and stored for 16 h at room temperature.

[0212] Subsequently the one-component water-based paint was prepared as described hereinabove and likewise applied over the entire surface with a Satajet HVLP gravity spray gun, 1.2 mm, air pressure 2.1 bar, in 1 cross-pass to obtain a (dry) layer thickness of 9-12 m. The basecoat was dried for 10 min at room temperature and for 30 min at 80° C. in a forced circulation oven and stored for 3 h at room temperature.

[0213] Finally the solvent-based clearcoat was produced as described hereinabove and immediately after mixing of the masterbatch and the hardener applied with a Satajet HVLP gravity spray gun, 1.2 mm, air pressure 2.1 bar, in 1 cross-pass to obtain a (dry) layer thickness of 25-32 M. The clearcoat was dried for 10 min at room temperature and for 45 min at 80° C. in a forced circulation oven.

[0214] Visual Assessment of the Painted Overall Constructions:

[0215] The visual assessment of the surface of the overall constructions composed of the substrate layer, top layer and paint was undertaken after aging of the coated sheets for at least 16 h at 60° C. in a forced circulation oven followed by 8 h of storage at room temperature. The results of the visual assessment are shown in table 5.

[0216] A score of “1” was assigned if the painted substrate layer-top layer laminate was free from bubbles, sink marks, blisters or cracks and if fibers from the substrate underneath the film were at most minimally visible on the surface.

[0217] A score of “2” was assigned if the painted substrate layer-top layer laminate was free from bubbles, sink marks, blisters or cracks but fibers from the substrate underneath the film were visible on the surface.

[0218] A score of “3” was assigned if the coated substrate layer-top layer laminates exhibited bubbles, sink marks, blisters and/or cracks.

[0219] It was found that scores of 1 and 2 could only be achieved with a certain concentration of the polyester components B1 to B4 in the top layer while bubbles, sink marks, blisters and/or cracks always occurred after painting (example 17, score 3) without admixture of a polyester component (when using pure component A).

[0220] When using PBT (B1) and PET (B2) as polyester components, good painted finish results were achieved from a content as low as 18% by weight based on the total weight of the composition of the top layer (examples 2-4 and 6-8). When using PBT the visual appearance of the surfaces was also markedly improved from as low as 36% by weight since fibers from the substrate underneath the film were less visible at the painted surface (example 3) while when using PET this effect was only apparent from a higher concentration in the top layer (example 8).

[0221] When using B3 as the polyester component good painted finish results were achieved from a content as low as 9% by weight based on the total weight of the composition of the top layer (examples 9-12), wherein the visual appearance of the surfaces was markedly improved from 36% by weight since fibers from the substrate underneath the film were less visible at the painted surface (examples 11 and 12).

[0222] When using PEN (B4) as the polyester component good painted finish results were achieved only above a higher content of 36% by weight based on the total weight of the composition of the top layer (examples 15 and 16) while fibers from the substrate underneath the film were still visible at the painted surface to a significant extent and the score of 1 was accordingly unachievable.

TABLE-US-00004 TABLE 4 (E: inventive example; V: comparative example; all reported data in % by wt, based on the total weight of the composition): 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 (V) (E) (E) (E) (V) (E) (E) (E) (E) (E) (E) (E) (V) (V) (E) (E) (V) (A) 80.09 71.19 53.39 35.6  80.09 71.19 53.39 35.6  80.09 71.19 53.39 35.6  80.09 71.19 53.39 35.6  100 (B1)  8.9  17.8  35.6  53.39 (B2)  8.9  17.8  35.6  53.39 (B3)  8.9  17.8  35.6  53.39 (B4)  8.9  17.8  35.6  53.39 (C) 10.0  10.0  10.0  10.0  10.0  10.0  10.0  10.0  10.0  10.0  10.0  10.0  10.0  10.0  10.0  10.0  (D1)  0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1  (D2)  0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1   0.1  (D3)  0.01  0.01  0.01  0.01  0.01  0.01  0.01  0.01  0.01  0.01  0.01  0.01  0.01  0.01  0.01  0.01 (E)  0.8   0.8   0.8   0.8   0.8   0.8   0.8   0.8   0.8   0.8   0.8   0.8   0.8   0.8   0.8   0.8 

TABLE-US-00005 TABLE 5 (E: inventive example; V: comparative example) Composite with film 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 made of composition (V) (E) (E) (E) (V) (E) (E) (E) (E) (E) (E) (E) (V) (V) (E) (E) (V) Evaluation of surface Score 3 2 1 1 3 2 2 1 2 2 1 1 3 3 2 2 3 quality after painting