WO2022106534A1

WO2022106534A1 - Improving reflectance and yellowness index of thermoplastic reflective white compositions

Info

Publication number: WO2022106534A1
Application number: PCT/EP2021/082131
Authority: WO
Inventors: Rolf Wehrmann; Anke Boumans
Original assignee: Covestro Deutschland Ag
Priority date: 2020-11-23
Filing date: 2021-11-18
Publication date: 2022-05-27
Also published as: CN116547354A; EP4247888A1

Abstract

Described is a graft polymer of (meth)acrylic acid(C₁-C₈)-alkyl ester on a graft base from the group of the acrylate rubbers for increasing reflectance and/or reducing the yellowness index of a titanium dioxide-containing thermoplastic composition. The invention describes in particular the use of the additive to improve the reflectance of polycarbonate-based reflective white compositions that can be use in the field of reflectors.

Description

Improvement of the reflection and the yellowness index of thermoplastic reflective white

compositions

The invention relates to improving the reflection and/or the yellowness index of thermoplastic compositions containing titanium dioxide. In addition to increased reflection and an improved yellowness index, the compositions exhibit good melt stability.

It is known in the prior art to add titanium dioxide to plastics such as polycarbonate in order to obtain compositions to be used where good reflective properties are required. Such compositions are also referred to as “reflective white” compositions. In particular, thermoplastic compositions are of interest here, since they are easy to process and can be converted relatively easily into a wide variety of molded parts.

CN 109867941 A, for example, describes a corresponding reflective polycarbonate material which contains titanium dioxide, a liquid silicone and other polymeric components.

There is a demand for components, e.g. At the same time, however, the melt stability of the compositions should not suffer from the improvement in reflection, because a lack of processing stability and the polycarbonate degradation directly associated with it lead to an increase in the yellowness index (Y.I.), which has a negative effect on reflection.

The task was therefore to further improve the reflection of thermoplastic compositions containing titanium dioxide, whereby the melt stability, preferably determinable using the melt volume flow rate (MVR; Melt Flow Ratio, ISO 1133:2012-03), should not be significantly negatively changed . In the case of compositions which are pure white without the new additive, the addition of the new additive and thus the improvement in reflection should, as far as possible, be associated with no disruptive color cast.

Optical brighteners that could be added have the disadvantage that when used, they lead to a non-linear reflection curve, which can lead to a blue color cast in the material, which is perceived as annoying.

It has surprisingly been found that the use of graft polymers of (meth)acrylic acid-(Ci- to -Cx)-alkylcstcr on a graft base from the group of acrylate rubbers, in particular acrylic core/shell graft polymer based on butyl acrylate rubber, below referred to as "Component C", leads to an improvement in reflection in thermoplastic compositions containing titanium dioxide. At the same time, a fundamentally positive effect on the yellowness index can even be observed. The flow behavior of the compositions is not significantly affected and the good processability in injection molding is retained.

SUBSTITUTE SHEET (RULE 26) The invention thus relates to the use of a graft polymer of (meth)acrylic acid (C1- to -C8)-alkyl ester on a graft base from the group of acrylate rubbers to increase the reflection of a thermoplastic composition containing titanium dioxide. The reflection is preferably determined according to ASTM E 1331-2015 with a layer thickness of 2 mm. The improvement in reflection relates to the corresponding compositions without such a graft polymer, preferably without an acrylic core/shell graft polymer based on butyl acrylate rubber (graft base), in particular with polymethyl methacrylate as the shell material. It goes without saying that a corresponding comparative composition is otherwise identical to the composition resulting from the use according to the invention and merely has a little more thermoplastic polymer instead of component C.

The reflection of the compositions in which the reflection is further improved by the addition of component C is preferably at least 94%, particularly preferably at least 96%, before the addition of component C, determined according to ASTM E 1331-2015 with a layer thickness of 2 mm.

The invention alternatively or additionally also preferably uses graft polymers of (meth)acrylic acid (C 1 -C 8 ) alkyl esters on a graft base from the group of acrylate rubbers to improve, ie reduce, the yellowness index determined according to ASTM E 313-15 (observer 10° / type of light: D65) on sample plates with a layer thickness of 2 mm. Again, the reference is the same as described above. Component C not only improves the reflection and reduces the yellowness index, but at the same time the degradation during compound production is usually reduced and the melt is stabilized during the injection molding process, which represents an outstanding combination of effects.

Thermoplastic compositions in which the addition of a graft polymer of (meth)acrylic acid (C1- to -C8)-alkyl ester on a graft base from the group of acrylate rubbers improves the reflection, the yellowness index and possibly also melt stabilization , preferably included

A) 50 to 94.5% by weight thermoplastic polymer,

B) 5 to 25% by weight titanium dioxide,

C) 0.5 to 5% by weight of graft polymer of (meth)acrylic acid (Ci to -C8) alkyl ester on a graft base from the group of acrylate rubbers,

D) 0 to 20% by weight of further additives.

More preferably, the compositions resulting from the use according to the invention contain no further components, but instead components A to D add up to 100% by weight, i.e. the compositions consist of these components A to D.

SUBSTITUTE SHEET (RULE 26) It goes without saying that the components used can contain the usual impurities which, for example, result from their production processes. It is preferred to use components that are as pure as possible. It is also understood that these impurities can also be contained in a closed formulation of the composition.

A core/shell graft polymer based on butyl acrylate rubber, in particular with a shell based on polymethyl methacrylate, is preferred, alone or in combination with other representatives of the graft polymers of (meth)acrylic acid-(C1- to -C8)-alkyl esters on a graft base from the group of acrylate rubbers used as component C.

Component C and the other ingredients of the compositions in which component C is to be used are explained in more detail below.

Component A

Thermoplastic compositions in the sense of the invention are preferably those based on one or more of the following plastics. "Based on" here means a proportion of at least 50% by weight, more preferably at least 60% by weight, even more preferably at least 65% by weight, particularly preferably at least 70% by weight, of such plastics in the composition. Examples of these plastics are: polycarbonates, especially aromatic polycarbonates, polystyrenes, polyacrylates, such as polymethyl methacrylates, styrene-acrylonitriles, cyclo-olefin copolymers, polyamides, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyetherimides, combinations of two or more of these plastics. More preferably, the thermoplastic composition contains aromatic polycarbonate. The thermoplastic composition is particularly preferably based on aromatic polycarbonate. Component A is very particularly preferably exclusively aromatic polycarbonate. A single polycarbonate or a mixture of different polycarbonates can be used.

“Polycarbonate” in the sense of the invention is understood to mean both aromatic homopolycarbonates and aromatic copolycarbonates. The polycarbonates can be linear or branched in a known manner.

The polycarbonates contained in the compositions are prepared in a known manner from dihydroxyaryl compounds, carbonic acid derivatives, optionally chain terminators and branching agents.

Details of the production of polycarbonates have been laid down in many patent specifications for about 40 years. For example see Schnell, "Chemistry and Physics of Polycarbonates", Polymer Reviews, Volume 9, Interscience Publishers, New York, London, Sydney 1964, see D. Freitag, U. Grigo, P.R. Müller, H. Nouvertne, BAYER AG, "Polycarbonates" in Encyclopedia of Polymer Science and Engineering, Volume 11, Second Edition, 1988, pages 648-718 and finally to U. Grigo, K. Kirchner

SUBSTITUTE SHEET (RULE 26) and PR Müller "Polycarbonate" in Becker/Braun, Kunststoff-Handbuch, Volume 3/1, Polycarbonate, Polyacetal, Polyester, Celluloseester, Carl Hanser Verlag Munich, Vienna 1992, pages 117 to 299.

Aromatic polycarbonates are produced, for example, by reacting dihydroxyaryl compounds with carbonic acid halides, preferably phosgene, and/or with aromatic dicarboxylic acid dihalides, preferably benzenedicarboxylic acid dihalides, by the phase interface process, optionally using chain terminators and optionally using trifunctional or more than trifunctional branching agents. Production via a melt polymerization process by reacting dihydroxyaryl compounds with, for example, diphenyl carbonate is also possible.

Examples of dihydroxyaryl compounds suitable for producing the polycarbonates are hydroquinone, resorcinol, dihydroxydiphenyls, bis(hydroxyphenyl)alkanes, bis(hydroxyphenyl)cycloalkanes, bis(hydroxyphenyl) sulfides, bis(hydroxyphenyl) ethers, bis( hydroxyphenyl) ketones, bis(hydroxyphenyl) sulfones, bis(hydroxyphenyl) sulfoxides, a-a'-bis(hydroxyphenyl)diisopropylbenzenes, phthalimidines derived from isatin or phenolphthalein derivatives, and their nucleus-alkylated, nucleated and nuclear halogenated compounds.

Preferred dihydroxyaryl compounds are 4,4'-dihydroxydiphenyl, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,4-bis(4-hydroxyphenyl)-2-methylbutane, l,l-bis- (4-hydroxyphenyl)-p-diisopropylbenzene, 2,2-bis(3 -methyl -4-hydroxyphenyl)propane, dimethyl -bisphenol A, bis(3,5-dimethyl-4-hydroxyphenyl)methane, 2 ,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, bis(3,5-dimethyl-4-hydroxyphenyl)sulfone, 2,4-bis(3,5-dimethyl-4- hydroxyphenyl)-2-methylbutane, 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)-p-diisopropylbenzene and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, as well as the bisphenols (I) to (III)

in which R 'in each case for C- to C4-alkyl, aralkyl or aryl, preferably for methyl or phenyl, very particularly preferably for methyl, is.

Particularly preferred bisphenols are 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-bis(4 -hydroxyphenyl)-cyclohexane, 1,1-bis(4-hydroxyphenyl)-

SUBSTITUTE SHEET (RULE 26) 3,3,5-trimethylcyclohexane, 4,4'-dihydroxydiphenyl and dimethyl bisphenol A and the bisphenols of the formulas (I), (II) and (III).

These and other suitable dihydroxyaryl compounds are described, for example, in US Pat. in DE 1 570 703 A, DE 2063 050 A, DE 2 036 052 A, DE 2 211 956 A and DE 3 832 396 A, in FR 1 561 518 A, in the monograph "H. Schnell, Chemistry and Physics of Polycarbonates , Interscience Publishers, New York 1964" and in JP 62039/1986 A, JP 62040/1986 A and JP 105550/1986 A.

In the case of homopolycarbonates, only one dihydroxyaryl compound is used; in the case of copolycarbonates, several dihydroxyaryl compounds are used.

Examples of suitable carbonic acid derivatives are phosgene or diphenyl carbonate.

Suitable chain terminators that can be used in the production of the polycarbonates are monophenols. Suitable monophenols are, for example, phenol itself, alkyl phenols such as cresols, p-tert. -butylphenol, cumylphenol and mixtures thereof.

Preferred chain terminators are the phenols which are linear or branched, preferably unsubstituted, one or more times with C 1 - to C 5 -alkyl radicals, or substituted with tert-butyl. Particularly preferred chain terminators are phenol, cumylphenol and/or p-tert-butylphenol.

The amount of chain terminator to be used is preferably 0.1 to 5 mol %, based on moles of dihydroxyaryl compounds used in each case. The chain terminators can be added before, during or after the reaction with a carbonic acid derivative.

Suitable branching agents are the trifunctional or more than trifunctional compounds known in polycarbonate chemistry, in particular those having three or more than three phenolic OH groups.

Examples of suitable branching agents are 1,3,5-tri(4-hydroxyphenyl)benzene, 1,1,1-tri(4-hydroxyphenyl)ethane, tri(4-hydroxyphenyl)phenylmethane, 2,4- Bis(4-hydroxyphenylisopropyl)-phenol, 2,6-bis(2-hydroxy-5'-methyl-benzyl)-4-methylphenol, 2-(4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl) -propane, tetra-(4-hydroxyphenyl)methane, tetra-(4-(4-hydroxyphenylisopropyl)phenoxy)methane and 1,4-bis-((4',4"-dihydroxytriphenyl)methyl)benzene and 3,3-bis(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole.

The amount of any branching agents to be used is preferably 0.05 mol % to 2.00 mol %, based on moles of dihydroxyaryl compounds used in each case.

The branching agents can either be presented with the dihydroxyaryl compounds and the chain terminators in the aqueous alkaline phase or dissolved in an organic solvent before

SUBSTITUTE SHEET (RULE 26) Phosgenation are added. In the case of the transesterification process, the branching agents are used together with the dihydroxyaryl compounds.

Particularly preferred polycarbonates are the homopolycarbonate based on bisphenol A, the copolycarbonates based on 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and 4,4′-dihydroxydiphenyl and the copolycarbonates based on of the two monomers bisphenol A and 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and of the dihydroxyaryl compounds of the formulas (I), (II) and (III)

in which R 'in each case stands for C 1 - to C 4 -alkyl, aralkyl or aryl, preferably for methyl or phenyl, very particularly preferably for methyl, derived homo- or copolycarbonates, in particular with bisphenol A.

Preference is also given to copolycarbonates produced using diphenols of the general formula (Ia):

whereby

R ⁵ is hydrogen or Ci to C4 alkyl, Ci to Cs alkoxy, preferably hydrogen; methoxy or methyl,

R ⁶ , R ⁷ , R ⁸ and R ⁹ each independently represent Ci- to C-alkyl or Ce- to Ci2-aryl, preferably methyl or phenyl,

Y for a single bond, SO2-, -S-, -CO-, -O-, Ci- to C ₍ , -alkylene. C2- to Cs-alkylidene, C - to C12- arylene, which optionally with further heteroatoms-containing aromatic Rings may be fused or for a C5 to Cö-cycloalkylidene which is sub- or polysubstituted with Ci to C -alkyl

SUBSTITUTE SHEET (RULE 26) may be situated, preferably for a single bond, -O-, isopropylidene or for a C5- to C ₍ ,- cycloalkylidene radical which may be mono- or polysubstituted by Ci to C's-alkyl,

V is oxygen, C2- to Ce-alkylene or C3- to C6-alkylidene, preferably oxygen or Cs-alkylene, p, q and r are each independently 0 or 1 when q=0, W is a single bond , when q = 1 and r = 0, W is oxygen, C2- to G-alkylene or C3- to G-alkylidcn. preferably represents oxygen or Cs-alkylene when q = 1 and r = 1, W and V each independently represent C2- to C ₍ -, -alkylene or C3- to G>-alkylidcn. preferably C3-alkylene,

Z is a Ci to Ce -alkylene, preferably Cs-alkylene, o is an average number of repeating units of 10 to 500, preferably 10 to 100, and m is an average number of repeating units of 1 to 10, preferably 1 to 6, more preferably 1.5 to 5. It is also possible to use diphenols in which two or more siloxane blocks of the general formula (Ia) are linked to one another via terephthalic acid and/or isophthalic acid to form ester groups.

Particular preference is given to (poly)siloxanes of the formulas (2) and (3)

where RI is hydrogen, C 1 -C 4 -alkyl, preferably hydrogen or methyl and particularly preferably hydrogen,

R2 independently for aryl or alkyl, preferably for methyl,

SUBSTITUTE SHEET (RULE 26) X for a single bond, -SO2-, -CO-, -O-, -S-, Ci- to G, -alkylene. C2- to Cs-alkylidene or C - to Ci2-arylene, which may optionally be fused with aromatic rings containing further heteroatoms,

X preferably represents a single bond, Ci to Cs-alkylene, C2 to Cs-alkylidene, C5 to C12-cycloalkylidene, -O-, -SO- -CO-, -S-, -SO2-, particularly preferably X represents a single bond, isopropylidene, C5 to C12 cycloalkylidene or oxygen, and very particularly preferably isopropylidene, n is an average number from 10 to 400, preferably 10 and 100, particularly preferably 15 to 50, and m is an average number from 1 to 10, preferably from 1 to 6 and particularly preferably from 1.5 to 5.

Also preferably, the siloxane block can be derived from the following structure

(VI), where a in formula (IV), (V) and (VI) is an average number of 10 to 400, preferably 10 to 100 and particularly preferably 15 to 50.

SUBSTITUTE SHEET (RULE 26) It is also preferred that at least two identical or different siloxane blocks of the general formulas (IV), (V) or (VI) are linked to one another via terephthalic acid and/or isophthalic acid to form ester groups.

It is also preferred if in the formula (Ia) p=0, V is Cs-alkylene, r=1, Z is Cs-alkylene, R ⁸ and R ⁹ are methyl, q=1, W is Cs-alkylene, m = 1, R ⁵ is hydrogen or Ci to C4-alkyl, preferably hydrogen or methyl, R ⁶ and R ⁷ are each independently Ci to C-ralkyl, preferably methyl and o is 10 to 500.

Copolycarbonates with monomer units of the formula (Ia) and in particular their preparation are described in WO 2015/052106 A2.

Copolycarbonates with monomer units of the formula (IV) and in particular also their production are described in WO 2015/052106 A2.

The thermoplastic polycarbonates, including the thermoplastic, aromatic polyester carbonates, preferably have weight-average molecular weights _Mw of 15,000 g/mol to 40,000 g/mol, more preferably up to 34,000 g/mol, particularly preferably 17,000 g/mol to 33,000 g/mol, in particular 19,000 g/mol to 32,000 g/mol, determined by gel permeation chromatography, calibrated against bisphenol A polycarbonate standards using dichloromethane as eluent, calibration with linear polycarbonates (from bisphenol A and phosgene) of known molar mass distribution from PSS Polymer Standards Service GmbH, Germany, calibration according to method 2301-0257502-09D (from 2009 in German) from Currenta GmbH & Co. OHG, Leverkusen. The eluent is dichloromethane. Column combination of crosslinked styrene-divinylbenzene resins. Analytical columns diameter: 7.5 mm; Length: 300mm Column material particle sizes: 3 pm to 20 pm. Concentration of the solutions: 0.2% by weight. Flow rate: 1.0 ml/min, temperature of solutions: 30°C. Using UV and/or RI detection.

Component B

The component C reflection improver to be used according to the invention is used for compositions which contain titanium dioxide as a white pigment.

These compositions preferably contain from 5% to 25.0%, more preferably from 5.0% to 20.0%, even more preferably from 8.0% to 18.0% by weight % by weight, particularly preferably from 10.0% by weight to 15.0% by weight, very particularly preferably from 11.0% by weight to 13.0% by weight, titanium dioxide.

The titanium dioxide according to component B of the compositions according to the invention preferably has an average particle size D50, determined by means of scanning electron microscopy (STEM), of 0.1 to 5 μm, preferably 0.2 μm to 0.5 μm. However, the titanium dioxide can also have a different particle size

SUBSTITUTE SHEET (RULE 26) sen, for example an average particle size D50, determined by means of scanning electron microscopy (STEM), of> 0.5 pm, about 0.65 to 1.15 pm.

The titanium dioxide preferably has a rutile structure.

The titanium dioxide used according to the invention is a white pigment, Ti(IV)C>2. In addition to titanium, colored titanium dioxides also contain significant amounts of elements such as Sb, Ni and Cr, resulting in a color impression other than “white”. It goes without saying that the white pigment titanium dioxide can also contain traces of other elements as impurities. However, these amounts are so small that the titanium dioxide does not acquire a color cast.

Suitable titanium dioxides are preferably those which are produced by the chloride process, made hydrophobic, specially post-treated and suitable for use in polycarbonate. In principle, instead of sized titanium dioxide, it is also possible to use unsized titanium dioxide or a mixture of both in compositions according to the invention. However, the use of sized titanium dioxide is preferred.

Possible surface modifications of titanium dioxide include inorganic and organic modifications. These include, for example, surface modifications based on aluminum or polysiloxane. An inorganic coating may contain 0.0% to 5.0% by weight silica and/or alumina. An organic based modification may contain from 0.0% to 3.0% by weight of a hydrophobic wetting agent. The titanium dioxide preferably has an oil absorption number, determined according to DIN EN ISO 787-5: 1995-10, from 12 to 18 g/100 g titanium dioxide, more preferably from 13 to 17 g/100 g titanium dioxide, particularly preferably from 13.5 to 15 .5 g/100 g titanium dioxide.

Particular preference is given to titanium dioxide with the standard designation R2 according to DIN EN ISO 591-1:2001-08, which is stabilized with aluminum and/or silicon compounds and has a titanium dioxide content of at least 96.0% by weight. Such titanium dioxides are available under the brand names Kronos 2233 and Kronos 2230.

Component C

The reflection improver to be used according to the invention, component C in the thermoplastic compositions, is preferably used in amounts of 0.5% by weight to 5.0% by weight, more preferably 0.8% by weight to 4.0% by weight. %, even more preferably 1% by weight to 3.5% by weight, particularly preferably 1% by weight to 3% by weight, very particularly preferably 1.0% by weight to 3.0% by weight %, used.

Component C is at least one graft polymer of (meth)acrylic acid-(Ci- to -Cx)-alkylcstcr on a graft base from the group of acrylate rubbers.

Component C is preferably one or more graft polymer(s) of

SUBSTITUTE SHEET (RULE 26) C. l 5 to 95, preferably 30 to 90 wt .-%, at least one (meth) acrylic acid (Ci to -Cs) - alkyl ester

C.2 95 to 5, preferably 70 to 10% by weight of at least one graft base selected from the group of acrylate rubbers.

Methyl methacrylate, alone or in a mixture with other monomers from the group of (meth)acrylic acid (C 1 -C 8 )-alkyl esters, is more preferably used as monomer C.1. The monomer C.1 is particularly preferably methyl methacrylate.

Suitable acrylate rubbers according to C.2 of the polymers C are preferably polymers of acrylic acid alkyl esters, optionally with up to 40% by weight, based on C.2, of other polymerizable, ethylenically unsaturated monomers. The preferred polymerizable acrylic acid esters include Ci to Cx-alkylcstcr. for example methyl, ethyl, butyl, n-octyl and 2-ethylhexyl esters; Haloalkyl esters, preferably halo-Ci- to -G-alkylcstcr. such as chloroethyl acrylate and mixtures of these monomers.

For crosslinking, monomers having more than one polymerizable double bond can be copolymerized. Preferred examples of crosslinking monomers are esters of unsaturated monocarboxylic acids having 3 to 8 carbon atoms and unsaturated monohydric alcohols having 3 to 12 carbon atoms, or saturated polyols having 2 to 4 OH groups and 2 to 20 carbon atoms, such as ethylene glycol dimethacrylate, allyl methacrylate ; polyunsaturated heterocyclic compounds such as trivinyl and triallyl cyanurate; polyfunctional vinyl compounds such as di- and trivinylbenzenes; but also triallyl phosphate and diallyl phthalate. Preferred crosslinking monomers are allyl methacrylate, ethylene glycol dimethacrylate, diallyl phthalate and heterocyclic compounds containing at least three ethylenically unsaturated groups. Particularly preferred crosslinking monomers are the cyclic monomers triallyl cyanurate, triallyl isocyanurate, triacryloylhexahydro-s-triazine, triallylbenzenes. The amount of crosslinked monomers is preferably from 0.02 to 5% by weight, in particular from 0.05 to 2% by weight, based on the graft base C.2. In the case of cyclic crosslinking monomers having at least three ethylenically unsaturated groups, it is advantageous to limit the amount to less than 1% by weight of the graft base C.2.

Preferred "other" polymerizable, ethylenically unsaturated monomers which, in addition to the acrylic acid esters, can optionally be used to prepare the graft base C.2, are, for example, acrylonitrile, styrene, a-methylstyrene, acrylamides, vinyl-C1- to -C ₍ ,-alkylcthcr. methyl methacrylate , Butadiene Preferred acrylate rubbers as the graft base C.2 are emulsion polymers which have a gel content of at least 60% by weight.

SUBSTITUTE SHEET (RULE 26) At least butyl acrylate rubber, alone or in a mixture with other acrylate rubbers, is more preferably used as the graft base C.2. Component C.2 is particularly preferably butyl acrylate rubber, in particular n-butyl acrylate rubber.

The graft base C.2 preferably has an average particle size (dso value) of 0.05 to 10 μm, preferably 0.1 to 5 μm, particularly preferably 0.2 to 0.4 μm. The mean particle size dso is the diameter above and below which 50% by weight of the particles are in each case. It can be determined by means of an ultracentrifuge measurement (W. Scholtan, H. Lange, Colloid, Z. and Z. Polymere 250 (1972), 782-796).

The gel content of the graft base C2 is determined at 25° C. in a suitable solvent (M. Hoffmann, H. Kroemer, R. Kuhn, Polymeranalytik I and II, Georg Thieme-Verlag, Stuttgart 1977). The gel content of the graft base C.2 is preferably at least 20% by weight, in the case of graft bases C.2 produced in emulsion polymerization preferably at least 40% by weight (measured in toluene, M. Hoffmann, H. Krämer, R. Kuhn, Polymer analysis I and II, Georg Thieme-Verlag, Stuttgart 1977).

The graft bases C.2 generally have a glass transition temperature of <10°C, preferably <0°C, particularly preferably <-10°C. The glass transition temperature is determined using dynamic differential thermal analysis (DSC) in accordance with the standard DIN EN 61006 (DIN EN 61006:2004-11) at a heating rate of 10 K/min with the definition of the T _g as the midpoint temperature (tangent method).

The graft polymer composed of components C.1 and C.2 preferably has a core-shell structure, with component C.1 forming the shell (also referred to as the shell) and component C.2 forming the core (see, for example, Ullmann's Encyclopedia of Industrial Chemistry, VCH-Verlag, Vol. A21, 1992, page 635 and page 656).

The graft copolymers C are prepared by free-radical polymerization, for example by emulsion, suspension, solution or bulk polymerization, preferably by emulsion or bulk polymerization.

Since, as is known, the graft monomers are not necessarily completely grafted onto the graft base in the graft reaction, graft polymers C are also understood according to the invention as products which are obtained by (co)polymerization of the graft monomers in the presence of the graft base and are also obtained during work-up.

The weight-average molar weight of the graft polymers used as component C is preferably from 15,000 to 200,000 g/mol, particularly preferably from 80,000 to 150,000 g/mol, determined by light

SUBSTITUTE SHEET (RULE 26) Scattering in methylene chloride. Component C preferably has a melting range of 130°C to 150°C.

A particularly suitable component C is a core/shell graft polymer based on butyl acrylate rubber (butyl acrylate rubber as the graft base). Polybutyl acrylate is the base of the core, the shell is preferably based on polymethyl methacrylate. "Based" in this context is to be understood as meaning that it is the main material of the core or shell, i.e. the material whose weight makes up at least 50% by weight of the total material of the core or shell. “Based” very particularly preferably means that the respective material is the material of the core or the shell. Core/shell graft polymer based on butyl acrylate rubber, in particular with a shell based on polymethyl methacrylate, as a representative of component C can be present as component C alone or in a mixture with other suitable representatives of component C. A suitable graft polymer is available under the name “Paraloid EXL2300” from Dow.

Component D

The compositions in which the reflection improver to be used according to the invention is used can contain further customary additives as component D. It is preferably up to 20% by weight, more preferably up to 10% by weight, even more preferably from 0.1% by weight to 6.0% by weight, particularly preferably from 0.1% by weight to 3.0% by weight, very particularly preferably 0.2% by weight to 1.0% by weight, in particular up to 0.5% by weight, of other customary additives (“further additives”). The group of other additives does not include titanium dioxide, as this has already been described as component B. The group of other additives also does not include the reflection improver to be used according to the invention, i.e. no graft polymer according to component C, i.e. no graft polymer of (meth)acrylic acid-(Ci- to -Cx)-alkylcstcr on a graft base from the group of acrylate rubbers.

Such further additives as are usually added to polycarbonates are, in particular, thermal stabilizers, antioxidants, mold release agents, UV absorbers, IR absorbers, impact modifiers other than component C, antistatic agents, optical brighteners, fillers other than component B, flame retardants, anti-drip agents, light scattering agents, Hydrolysis stabilizers, transesterification stabilizers, further flow improvers, compatibilizers and/or additives for laser marking, in particular in the amounts customary for polycarbonate-based compositions. Such additives are described, for example, in EP-A 0 839 623, WO-A 96/15102, EP-A 0 500 496 or in “Plastics Additives Handbook”, Hans Zweifel, 5th Edition 2000, Hanser Verlag, Munich. These additives can be added individually or as a mixture. It goes without saying that only such additives and only in such amounts may be added if they do not have a significantly negative effect on the inventive effect of improved reflection. Compositions according to the invention therefore preferably contain no carbon black, for example. There must continue to be an improvement in reflection

SUBSTITUTE SHEET (RULE 26) be observed over such corresponding reference compositions, which differ from the composition according to the invention only in that they contain no impact modifier according to component C.

There are preferably no organic colorants, organic or inorganic pigments in the compositions. It is also preferred that no carbon black is present.

Additives contained with particular preference are heat stabilizers. Phosphorus-based stabilizers selected from the group consisting of phosphates, phosphites, phosphonites, phosphines and mixtures thereof are particularly suitable as thermal stabilizers. Mixtures of different compounds from one of these subgroups can also be used, for example two phosphites. Phosphorus compounds with the oxidation number +III, in particular phosphines and/or phosphites, are preferably used as thermal stabilizers. Particularly suitable thermal stabilizers are triphenylphosphine, tris-(2,4-di-tert-butylphenyl)phosphite (Irgafos® 168), tetrakis-(2,4-di-tert-butylphenyl)-[1,1-biphenyl]- 4,4'-diylbisphosphonite, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Irganox® 1076), bis-(2,4-dicumylphenyl)pentaerythritol diphosphite (Doverphos® S- 9228), bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (ADK STAB PEP-36). They are used alone or in a mixture, e.g. B. Irganox® B900 (mixture of Irgafos® 168 and Irganox® 1076 in a ratio of 4: 1) or Doverphos® S- 9228 with Irganox® B900 or Irganox® 1076. The heat stabilizers are preferably used in amounts up to 1.0% by weight, more preferably from 0.003% to 1.0% by weight, even more preferably from 0.005% to 0.5% by weight, especially preferably 0.01% by weight to 0.2% by weight.

Preferred additives are also special UV stabilizers which have the lowest possible transmission below 400 nm and the highest possible transmission above 400 nm. Ultraviolet absorbers which are particularly suitable for use in the composition according to the invention are benzotriazoles, triazines, benzophenones and/or arylated cyanoacrylates. Particularly suitable ultraviolet absorbers are hydroxy-benzotriazoles, such as 2-(3',5'-bis-(1,1-dimethylbenzyl)-2'-hydroxy-phenyl)-benzotriazole (Tinuvin® 234, BASF SE, Ludwigshafen), 2-(2'-Hydroxy-5'-(tert.-octyl)-phenyl)-benzotriazole (Tinuvin® 329, BASF SE, Ludwigshafen), bis-(3-(2H-benzotriazolyl)-2-hydroxy-5- tert-octyl)methane (Tinuvin® 360, BASF SE, Ludwigshafen), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-(hexyloxy)-phenol (Tinuvin® 1577 , BASF SE, Ludwigshafen), 2-(5chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methyl-phenol (Tinuvin® 326, BASF SE, Ludwigshafen), and benzophenones such as 2,4-dihydroxybenzophenone (Chimasorb® 22, BASF SE, Ludwigshafen) and 2-hydroxy-4-(octyloxy)benzophenone (Chimassorb® 81, BASF SE, Ludwigshafen), 2,2-bis[[(2-cyano- 1-oxo-3,3-diphenyl-2-propenyl)oxy]-methyl]-1,3-propanediyl ester (9CI) (Uvinul 3030, BASF SE, Ludwigshafen), 2-[2-hydroxy-4-(2- ethylhexyl)oxy]phenyl-4,6-di(4-phenyl)phenyl-1,3,5-triazine (Tinuvin® 1600, BASF SE, Ludwigshafen), Tetraet hyl -2,2'-(1,4-phenylene-dimethylidene)-bismalonate (Hostavin B-Cap, Clariant AG) or N-(2-ethoxyphenyl)-N'-(2-ethylphenyl)-ethanediamide (Tinuvin® 312 , CAS no. 23949-66-8, BASF SE, Ludwigshafen).

SUBSTITUTE SHEET (RULE 26) Particularly preferred special UV stabilizers are Tinuvin® 360, Tinuvin® 329, Tinuvin® 326, Tinuvin® 1600, Tinuvin® 312, Uvinul® 3030, Cyasorb® UV-3638F and/or Hostavin B-Cap, which are very particularly preferred Tinuvin® 329 and Tinuvin® 360.

Mixtures of the ultraviolet absorbers mentioned can also be used.

If UV absorbers are present, the composition preferably contains ultraviolet absorbers in an amount of up to 0.8% by weight, preferably 0.05% by weight to 0.5% by weight, more preferably 0.08% by weight. -% to 0.4% by weight, very particularly preferably 0.1% by weight to 0.35% by weight, most preferably 0.15 to 0.2% by weight, based on the total composition.

The compositions may also contain phosphates or sulfonic acid esters as transesterification inhibitors. Triisooctyl phosphate is preferably present as a transesterification inhibitor. Triisooctyl phosphate is preferred in amounts of from 0.003% to 0.05%, more preferably from 0.005% to 0.04%, and most preferably from 0.01% to 0.03% by weight % by weight, based on the total composition.

The compositions may also contain flow improvers, e.g., diglycerol ester or diglycerol ester/carboxylic acid mixtures.

Examples of impact modifiers other than component C are: other core-shell polymers such as ABS or MBS; Olefin-acrylate copolymers such as. B. Elvaloy® grades from DuPont; Silicone acrylate rubbers such. B. the Metablen® grades from Mitsubishi Rayon Co., Ltd.

If one or more antidrip agents are present, their total amount is preferably 0.1% by weight to 0.8% by weight, in particular 0.10% by weight to 0.8% by weight, more preferably 0.15% by weight Wt% to 0.7 wt%, more preferably 0.4 wt% to 0.6 wt%.

SUBSTITUTE SHEET (RULE 26) A fluorine-containing polymer, in particular polyolefin, is preferably used as the anti-drip agent.

The fluorinated polyolefins used with particular preference as anti-drip agents are of high molecular weight and have glass transition temperatures above -30° C., usually above 100° C., fluorine contents preferably from 65% by weight to 76% by weight, in particular from 70 to 76% by weight %. Preferred fluorinated polyolefins are polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene/hexafluoropropylene and ethylene/tetrafluoroethylene copolymers. The fluorinated polyolefins are known (cf. "Vinyl and Related Polymers" by Schildknecht, John Wiley & Sons, Inc., New York, 1962, pages 484-494; "Fluoropolymers" by Wall, Wiley-Interscience, John Wiley & Sons, Inc., New York, Volume 13, 1970, pages 623-654, "Modem Plastics Encyclopedia", 1970-1971, Volume 47, No. 10 A, October 1970, Mc Graw-Hill, Inc., New York, page 134 and 774, "Modem Plastics Encyclopedia", 1975-1976, October 1975, Vol 723 373 and 3 838 092).

They can be prepared by known methods, for example by polymerizing tetrafluoroethylene in an aqueous medium with a catalyst which forms free radicals, for example sodium, potassium or ammonium peroxydisulfate at pressures of 7 to 71 kg/cm ² and at temperatures of 0 to 200° C, preferably at temperatures from 20 to 100°C. Further details are described, for example, in US Pat. No. 2,393,967.

Depending on the form of use, the density of the fluorinated polyolefins can be between 1.2 and 2.3 g/cm ³ , preferably 2.0 g/cm ³ to 2.3 g/cm ³ 'determined according to ISO 1183-1 (2019-09) , the mean particle size between 0.05 and 1000 pm, determined by light microscopy or white light interferometry.

Polytetrafluoroethylene (PTFE) or a PTFE-containing composition is particularly preferably used. PTFE is commercially available in various product qualities. These include Hostaflon® TF2021 or PTFE blends such as Blendex® B449 (approx. 50% by weight PTFE and approx. 50% by weight SAN [from 80% by weight styrene and 20% by weight acrylonitrile]) from Chemtura company. Blendex® B449 is preferably used.

Suitable tetrafluoroethylene polymer powders are commercially available products and are available, for example, from DuPont under the trade name Teflon®.

To incorporate additives, the thermoplastic on which the thermoplastic composition is based, or the thermoplastic mixture, is preferably used in the form of powders, granules or mixtures of powders and granules.

When using the reflection improvers to be used according to the invention for the stated purpose, these, like other additives, including titanium dioxide, are mixed with common incorporation

SUBSTITUTE SHEET (RULE 26) process by bringing together, mixing and homogenizing the individual components into corresponding compositions, with the homogenization in particular preferably taking place in the melt under the action of shearing forces. If appropriate, the bringing together and mixing takes place before the melt is homogenized using powder premixes.

Premixes of granules or granules and powders with the individual components can also be used.

It is also possible to use premixes which have been prepared from solutions of the mixture components in suitable solvents, with the solution optionally being homogenized and the solvent then being removed.

In particular, the components of the compositions can be introduced into the thermoplastic polymer, in particular into the polycarbonate, optionally into the polycarbonate with a blend partner, by known methods or as a masterbatch.

The use of masterbatches is preferred for introducing the respective components, individually or as a mixture.

In this context, the composition resulting according to the invention can be brought together, mixed, homogenized and then extruded in conventional devices such as screw extruders (for example twin-screw extruders, ZSK), kneaders, Brabender or Banbury mills. After extrusion, the extrudate can be cooled and chopped up. Individual components can also be premixed and then the remaining starting materials can be added individually and/or also mixed.

A premix can also be brought together and mixed in the melt in the plasticizing unit of an injection molding machine. In the subsequent step, the melt is transferred directly into a shaped body.

The compositions can be processed in a customary manner on customary machines, for example on extruders or injection molding machines, to give any moldings, such as films, sheets or bottles, for example.

The compositions resulting from the use of component C according to the invention are preferably used to produce moldings. The compositions preferably have a melt volume flow rate (MVR) of from 3 to 40 cm ³ /(10 min.), more preferably from 6 to 30 cm ³ /(10 min.), even more preferably from 8 to 25 cm ³ /(10 min ), particularly preferably from 9 to 24 cm ³ /(10 min), determined according to ISO 1133:2012-3 (test temperature 300° C., mass 1.2 kg).

SUBSTITUTE SHEET (RULE 26) The compositions particularly preferably consist of component C after use according to the invention

A) 60 to 94.5% by weight of thermoplastic polymer, aromatic polycarbonate being present as the thermoplastic polymer,

B) 5 to 25% by weight titanium dioxide,

D) 0 to 10 wt. anti-drip agents, flame retardants, light scattering agents, hydrolysis stabilizers, transesterification stabilizers, compatibilizers and/or laser marking additives, and combinations thereof.

Such compositions very particularly preferably consist of component C after use according to the invention

A) 67 to 91% by weight thermoplastic polymer, wherein the thermoplastic polymer is aromatic polycarbonate,

B) 8 to 20% by weight titanium dioxide,

C) 1 to 3 wt. C8) alkyl ester on a graft base from the group of acrylate rubbers is a core/shell graft polymer with butyl acrylate rubber as the graft base and the shell of the core/shell graft polymer with butyl acrylate rubber as the graft base is based on polymethyl methacrylate,

Extremely preferably at least one UV absorber is contained as a further additive, in particular a UV absorber selected from the group Cyasorb UV-3638F (2,2'-(1,4-phenylene)bis[4H-3,1-benzoxazine- 4-on]), Hostavin B-Cap (Tetraethyl -2,2'-(1,4-phenylenedimethylidene)bismalonate), Tinuvin 329 (2-(2'-Hydroxy-5'-(tert-octyl)phenyl)benzotriazole ), Uvinul 3030 (2,2-bis[[(2-cyano-1-oxo-3,3-diphenyl-2-propenyl)oxy]methyl]-1,3-propanediyl ester (9CI)), in particular in an amount from 0.1 to 0.35% by weight. The addition of UV absorbers, especially those mentioned above, leads to a further improvement

SUBSTITUTE SHEET (RULE 26) tion of the reflection. Component C is therefore preferably also used according to the invention in combination with a UV absorber, in particular with one of the aforementioned.

The use of component C to improve reflection is of particular interest where highly reflective compositions are required, i.e. in particular in the field of compositions for moldings for the lighting sector, which are, for example, reflectors or parts of reflectors of lamps, in particular LED lamps or LED arrays in the automotive sector, for example for headlight reflectors. However, the improvement in reflection can also be aimed at compositions that are used for molded parts, which are used for frames or frame parts, housing or housing parts in general in the EE (electrical/electronics) sector.

examples

1. Description of raw materials and test methods

The polycarbonate-based compositions described in the following examples were produced by compounding on a ZE 25 extruder from Berstorff with a throughput of 10 kg/h. The melt temperature was 275°C. a) raw materials

Component Al: Linear polycarbonate based on bisphenol A with a melt volume flow rate MVR of 19 cm ³ /(10 min) (according to ISO 1133:2012-03, at a test temperature of 300°C and 1.2 kg load), containing 250 ppm triphenylphosphine as component Dl (listed separately in the tables).

Component A-2: Linear polycarbonate in powder form based on bisphenol A with a melt volume flow rate MVR of 19 cm ³ /(10 min) (according to ISO 1133:2012-03, at a test temperature of 300°C and 1.2 kg Burden).

Component A-3: Linear polycarbonate based on bisphenol A with a melt volume flow rate MVR of 19 cm ³ /(10 min) (according to ISO 1133:2012-03, at a test temperature of 300°C and 1.2 kg load) .

Component A-4: polycarbonate from Covestro Deutschland AG. Linear polycarbonate based on bisphenol A with a melt volume flow rate MVR of 17 cm ³ /(10 min) (according to ISO 1133:2012-03, at a test temperature of 250°C and 2.16 kg load).

Component B-1: Kronos 2230 titanium dioxide from Kronos Titan GmbH, Leverkusen.

Component B-2: Kronos 2233 titanium dioxide from Kronos Titan GmbH, Leverkusen.

SUBSTITUTE SHEET (RULE 26) Component C: Paraloid EXL2300 from Dow. Acrylic core/shell graft polymer made from methyl methacrylate (shell) and butyl acrylate rubber (core, grafting base).

Component D-1: triphenylphosphine, commercially available from BASF SE, Ludwigshafen.

Component D-2: Blendex® B449 (about 50% by weight PTFE and about 50% by weight SAN [from 80% by weight styrene and 20% by weight acrylonitrile]) from Chemtura Corporation. antidrip agent.

Component D-3: Einar 601; Diglycerol ester from Palsgaard, Denmark

Component D-4: UV absorber Cyasorb UV-3638F. 2,2'-(1,4-phenylene)bis[4H-3,1-benzoxazin-4-one].

Component D-5: UV absorber Hostavin B-Cap. Tetraethyl -2,2'-(1,4-phenylenedimethylidene)bismalonate.

Component D-6: Tinuvin 329 UV absorber. 2-(2'-Hydroxy-5'-(tert-octyl)phenyl)benzotriazole.

Component D-7: UV absorber Uvinul 3030. 2,2-Bis[[(2-cyano-l-oxo-3,3-diphenyl-2-propenyl)oxy]methyl]-1,3-propanediyl ester (9CI) . b) test methods

The melt volume flow rate (MVR) was determined according to ISO 1133:2012-03 (mainly at a test temperature of 300° C., mass 1.2 kg) using the Zwick 4106 device from Zwick Roell. In addition, the MVR value was measured after 20 minutes of preheating (IMVR20'). This is a measure of melt stability under increased thermal stress.

The ash content was determined in accordance with DIN 51903:2012-11 (850°C, hold for 30 minutes).

The total reflectance spectrum was measured using a spectrophotometer based on the ASTM E 1331-04 standard. From the transmission or reflection spectrum obtained in this way, the visual transmission Ty (according to illuminant D65, observer 10°) or the visual reflection Ry (according to illuminant D65, observer 10°) were calculated in accordance with ASTM E 308-08. This also applies to the color values L*a*b*. The thickness of the specimens was 2 mm.

Gloss was determined according to ASTM D 523-14.

The yellowness index (Y.I.) was determined according to ASTM E 313-10 (observer: 10° / illuminant: D65).

The flammability of the tested samples was also assessed and classified according to UL94. For this purpose, specimens measuring 125 mm x 13 mm x d(mm) were produced, with the thickness d corresponding to the smallest wall thickness in the intended application. A V0

SUBSTITUTE SHEET (RULE 26) Classification means that the flame goes out by itself after a maximum of 10 s. Burning dripping does not occur. An afterglow after the second flaming occurs for a maximum of 30 s.

The Vicat softening point VST/B50 as a measure of heat resistance was determined in accordance with ISO 306:2013 on test specimens measuring 80 mm x 10 mm x 4 mm with a stamp load of 50 N and a heating rate of 50°C/h using the Coesfeld Eco device 2920 from Coesfeld Materialtest.

The sample plates were each produced by injection molding at the melt temperatures given in the tables below.

Comparative experiments are identified below with “V”, experiments according to the invention with “E”.

SUBSTITUTE SHEET (RULE 26) Table 1

The addition of only 1 wt Polycarbonate compositions (E-5 to E-8 vs. VI to V-4). With a further increase in the amount of component C to 3% by weight (E-9 to E-12), a further increase can likewise be observed. At the same time, the yellowness index is significantly improved. In addition, the melt is stabilized during processing of the compounds, and AMVR is noticeably reduced in the compositions that contain component C to be used according to the invention. At the same time, the starting values of the MVR of the examples containing component C to be used according to the invention are lower. Component C thus also brings about melt stabilization during compound production.

Table 2

A practically relevant improvement in reflection and a reduction in the yellowness index can also be observed in compositions with additives, in this case containing anti-drip agents, if component C is used.

SUBSTITUTE SHEET (RULE 26) Table 3

Two different types of titanium dioxide were used in examples E-19 to E-23 and E-26 to E-29, or V-17, V-18 and V-24 and V-25. While this does not appear to have a significant impact on most properties, the Yellowness Index is further improved when Kronos 2233 (E-26 to E-29) is used instead of Kronos 2230 (E-19 to E-23).

Table 4

Addition of component C also leads to an improvement in reflection and a reduction in the yellowness index in compositions containing flow improvers (E-35 to E-37 compared to V-31 to V-33).

Table 5

.b.: not determined

The addition of UV absorbers has also proven to be particularly advantageous according to the invention. The person skilled in the art would expect a reduction in reflection due to the intrinsic color of the UV absorbers. Surprisingly, however, the addition of UV absorbers leads to a further increase in reflection (E-39 to E-46 compared to E-38 without UV absorber).

Claims

patent claims

1. Use of graft polymer of (meth)acrylic acid (Ci to -Cg) alkyl ester on a graft base from the group of acrylate rubbers to increase the reflection and / or reduce the yellowness index of a titanium dioxide-containing thermoplastic composition.

2. Use according to any one of the preceding claims, wherein the thermoplastic composition contains the following components after the addition of component C:

A) 50 to 94.5% by weight thermoplastic polymer,

B) 5 to 25% by weight titanium dioxide,

D) 0 to 20% by weight of other additives.

3. Use according to claim 1 or 2, wherein the thermoplastic composition is based on aromatic polycarbonate.

4. Use according to any one of the preceding claims, wherein the thermoplastic composition contains at least 60% by weight of aromatic polycarbonate.

5. Use according to any one of the preceding claims, wherein the thermoplastic composition consists of the following components after the addition of component C:

B) 5 to 25% by weight titanium dioxide,

C) 0.5 to 5% by weight of graft polymer of (meth)acrylic acid (Ci to -Cs) alkyl ester on a graft base from the group of acrylate rubbers,

D) 0 to 10 wt. Flame retardants, light scattering agents, hydrolysis stabilizers, transesterification stabilizers, compatibilizers and/or additives for laser marking and combinations thereof.

6. Use according to any one of the preceding claims, wherein the graft polymer of (meth)acrylic acid (Ci to -Cs) alkyl ester on a graft base from the group of acrylate rubbers comprises a core / shell graft polymer with butyl acrylate rubber as the graft base .

7. Use according to any one of claims 1 to 6, wherein the graft polymer of (meth) acrylic acid (Ci to -Cs) alkyl ester on a graft from the group of acrylate rubbers is a core / shell graft polymer with butyl acrylate rubber as graft base is.

8. Use according to claim 6 or 7, wherein the shell of the core/shell graft polymer with butyl acrylate rubber as the grafting base is based on polymethyl methacrylate.

9. Use according to any one of the preceding claims, wherein the thermoplastic composition consists of the following components after the addition of component C:

B) 8 to 20% by weight titanium dioxide,

C) 1 to 3 wt. Cs) alkyl ester on a graft base from the group of acrylate rubbers is a core/shell graft polymer with butyl acrylate rubber as the graft base and the shell of the core/shell graft polymer with butyl acrylate rubber as the graft base is based on polymethyl methacrylate,

D) 0 to 10 wt , light scattering agents, hydrolysis stabilizers, transesterification stabilizers, compatibilizers and/or additives for laser marking, and combinations thereof.

10. Use according to one of the preceding claims, wherein the improvement in reflection relates to the comparison of two samples, of which the comparative sample represents a corresponding composition without component C and therefore contains correspondingly more thermoplastic polymer according to component A, but otherwise the same composition as the composition that results from the inventive use of the graft polymer of (meth)acrylic acid (Ci to -Cs) alkyl ester on a graft base from the group of acrylate rubbers.

11. Use according to any one of the preceding claims, wherein the thermoplastic composition contains at least one UV absorber.