EP1379381A1

EP1379381A1 - Heat-absorbing layer system

Info

Publication number: EP1379381A1
Application number: EP02722277A
Authority: EP
Inventors: Martin Döbler; Peter Bier; Rüdiger Gorny; Monika Stihler
Original assignee: Bayer AG
Current assignee: Covestro Deutschland AG
Priority date: 2001-04-10
Filing date: 2002-03-28
Publication date: 2004-01-14
Also published as: CN1501861A; KR20030090722A; JP2004529007A; WO2002083412A1; US20030039821A1; BR0208740A; US6893689B2; MXPA03009192A; CN100374293C; DE10117785A1; CA2443706A1; IL158253A0; ZA200307815B

Abstract

The invention relates to a transparent heat-absorbing layer system comprising a first layer (A) and a second layer (B). The invention is characterized in that the first layer (A) contains at least one organic infrared absorber and at least one UV absorber and the second layer (B) contains at least one UV absorber, while the first layer (A) is the only layer of the layer system that contains an organic infrared absorber. The invention further relates to the production of said layer system, to the use thereof and to the products produced therefrom.

Description

Heat absorbing layer system

The invention relates to a heat-absorbing layer system which contains at least a first layer (A) and a second layer (B), as well as to its production, use and products made therefrom.

Discs from compositions containing transparent thermoplastic polymers such. As polycarbonate, offer many northern parts for the automotive sector and for buildings compared to conventional glass discs such as. B. increased

Break resistance or weight saving. In the case of automobile glazing, this achieves higher occupant safety in traffic accidents and, thanks to the weight saving, lower fuel consumption. Finally, transparent thermoplastic polymers and compositions containing transparent thermoplastic polymers allow for a much greater freedom of design due to their easier formability.

However, the high thermal permeability (ie permeability to IR radiation) of transparent thermoplastic polymers leads to undesirable heating inside when exposed to the sun. Like Parry Moon, Journal of the Franklin

Institute 230, pages 583-618 (1940), most of the solar energy is attributable to the visible range of light between 400 and 750 µm and the range of near infrared (ΝIR) between 650 and 1100 nm , B. absorbed inside an automobile and emitted as long-wave heat radiation of 5 to 15 microns. Since conventional glass materials and in particular transparent thermoplastic polymers are not transparent in this area, the heat radiation cannot radiate to the outside. You get a greenhouse effect. In order to keep the effect as small as possible, the transmission of the glazing in the ΝIR should be minimized as much as possible. Usual transparent thermoplastic polymers such. B. are polycarbonate, however transparent in the visible area as well as in the NIR. There are therefore z. B. Additives are required which have the lowest possible transparency in the NIR with the highest possible transparency in the visible region of the spectrum.

For this purpose, infrared absorbers are described in the literature, which these

Restrict heating (e.g. J. Fabian, H. Nakazumi, H. Matsuoka, Chem. Rev. 92, 1197 (1992), US 5 712 332, JP 06240146 A).

Dyes with absorption maxima in the near infrared (NIR) are known for such applications. For outdoor applications, however, in addition to the required spectral properties, a high long-term light resistance against staining and fading is required.

A distinction is made between organic and inorganic ΝIR absorbers. Inorganic ΝIR absorbers usually show high light stability, but have the disadvantage that they are not soluble in thermoplastics and therefore form cloudy to opaque molding compounds. In contrast, organic NIR absorbers soluble in thermoplastics are known, but they show less light stability.

JP 10-077360 A describes thin, film-like heat-absorbing layer systems which simultaneously contain (A) a phthalocyanine infrared absorber and (B) an ultraviolet absorber. This is intended to improve the weather resistance of the heat protection layer. According to one embodiment, a film-like coating layer with a thickness of 0.13 mm is proposed, which contains both phthalocyanine infrared absorber and ultraviolet absorber. Such a coating layer has an acceptable weather resistance in 48-hour rapid weathering tests. For practical applications, however, weathering tests of more than 500 hours are required. Furthermore, the thin film-like coating described in this publication layer inadequate optical properties and are therefore unsuitable for use in automotive glazing.

In order to improve the weather resistance of heat-absorbing layer systems, JP 10-077360 A also proposes a thin, film-like, heat-absorbing coating of 3 layers with a gradual decrease in phthalocyanine infrared absorber. This contains an ultraviolet absorber in the upper layer facing the light radiation, a mixture of ultraviolet and phthalocyanine infrared absorbers in the middle layer and further phthalocyanine infrared absorbers in the lower layer facing away from the light radiation. A disadvantage of such a layer system is the costly three-layer structure and the poor optical properties of the layer system produced by lamination.

It is also generally known that certain thermoplastics can be protected by using UV-absorbing lacquers and / or coextruded layers with a high content of UV absorber. For example, it is known from EP 0 110 221 A to improve the weather resistance of polycarbonate plastic sheets by coating them with a layer containing 3 to 15% by weight of a UV absorber. The multilayer systems described in this publication do not contain an infrared absorber.

Finally, EP 0 774 551 A describes heat filters based on inorganic pigments which have a UV-absorbing protective layer. The disadvantage of inorganic pigments is that they do not dissolve in thermoplastics, so that there are no transparent moldings with low turbidity in the visible area.

The object of the invention is to provide heat-absorbing coating systems which are as simple and inexpensive as possible to produce excellent long-term weather resistance as well as excellent optical properties such as transparency and gloss and can be used for the thermal insulation of transparent plastic glazing elements.

According to the invention, this task is achieved by a transparent heat absorbing

Layer system containing a first layer (A) and a second layer (B), dissolved, the first layer (A) at least one organic infrared absorber and at least one ultraviolet absorber and the second layer (B) at least one ultraviolet absorber and the first layer (A) is the only layer in the layer system which contains an organic infrared absorber.

The heat-absorbing layer systems according to the invention are distinguished by the fact that organic infrared absorber and ultraviolet absorber are introduced together into one layer (layer A, “NIR / UV layer”). Because the two additives are present together in the same layer, a large part of the sensitive organic infrared absorber is protected against UV radiation. In addition, the organic infrared absorber is protected from decomposition by UV radiation by means of a further layer containing ultraviolet absorber (layer B, “UV layer”). It is also special that layer (A) is the only layer in the layer system according to the invention which contains organic IR absorbers. If appropriate, further layers contained in the layer system, such as clear layers, do not contain any organic infrared absorber. Since the UV layer (layer B) u. a. to protect NIR dye in layer (A) from UV rays, it is advantageous to arrange layer (B) in the direction of the incident light above layer (A). Starting with the side facing the light, the following is therefore

Layer structure advantageous: layer (B) - layer (A), in particular with the proviso that layer (A) serves simultaneously as a substrate (e.g. plastic car window). It is also possible to arrange one or more further layers (B) below layer (A), which leads, for example, to the following layer structure: layer (B) - layer (A) - layer (B). In this embodiment too, it is advantageous if Layer (A) also serves as a substrate (e.g. plastic car window). An example of this is a sheet of thermoplastic coextruded on both sides, containing organic infrared absorber and UV absorber [layer (A)] with two thin UV absorber layers on both sides [layer (B)]. Likewise possible is a double-coated plate or an injection molded part made of a thermoplastic containing organic infrared absorber and UV absorber [layer (A)] with UV absorber in both layers of lacquer [layer (B)].

It was surprisingly found that arranging a single UV protective layer above the NTR / UV layer sufficiently improved the long-term

Weather resistance and excellent gloss and transparency values of the heat-absorbing layer system can be obtained. The layer system according to the invention is distinguished from the single-layer thermal protection coating described in JP 10-077360 A by a significantly improved long-term weather behavior. Compared to the 3-layer thermal protection coating described in JP 10-077360 A, the layer system according to the invention is distinguished by considerably better transparency and gloss values and by a simpler and less expensive production. Contrary to the teaching of JP 10-077360, it was surprisingly found according to the invention that introducing NIR absorber into several layers for the purpose of achieving a gradual decrease in NIR absorber in the layer system is not necessary for an improvement in the Long-term weather resistance. By saving an additional NIR layer with the layer system according to the invention, the transparency and gloss behavior of the heat-absorbing layer system is also significantly improved.

Furthermore, it was found that it is advantageous if the individual layers of the layer system according to the invention are designed in a certain thickness. According to a preferred embodiment of the invention, the first layer (A) accordingly has a thickness of 2 to 8 mm, in particular 3 to 5 mm. According to one Another preferred embodiment of the invention, the second layer (B) has a thickness of 1 to 100 microns. In particular, it is advantageous if the second layer is designed as a polymer film with a thickness of 30 to 80 μm, in particular 40 to 60 μm. It is also possible to design the second layer as a lacquer with a thickness of 1 to 30 μm, in particular 4 to 10 μm.

Surprisingly, it was found that it is advantageous for the optical properties and for the long-term weather resistance of the heat-absorbing layer systems according to the invention that the NIR / UV layer (layer A) is not, as described in JP 10-077360 A, but as a thin, film-like coating layer in a thickness of 0.8 to 15 mm. This was surprising because thin layers generally have a better opacity than thick ones. A layer system in which a relatively thick NIR / UV layer (layer A) from 0.8 to 15 mm is coated with a relatively thin UV protective layer (layer B) from 1 to 100 μm has proven to be particularly advantageous. The coating can take place, for example, as a lacquer or as a thin polymer film. Such a layer system exhibits excellent transparency and clouding behavior with excellent long-term weather resistance. It has proven to be particularly advantageous if NIR / UV layer, both in terms of production technology and property-specific for use in automotive glazing

(Layer A) and UV layer (Layer B) and optionally further layers of the layer system are formed as coextruded polymer layers in the corresponding thicknesses.

According to a further preferred embodiment of the invention, the layer system according to the invention contains, in addition to layers (A) and (B), at least one further transparent layer (C) which contains neither an organic infrared absorber nor an ultraviolet absorber. Layer (C) is also referred to as "clear layer" and serves to improve the scratch resistance or to increase the mechanical rigidity. In the layer system according to the invention, one or There are clear layers. 1 to 3 clear layers are preferably used, particularly preferably 1 clear layer. The clear layers can be arranged anywhere in the layer system, ie above, below and / or between layers (A) and (B). However, a layer system with the following layer structure (starting with the one facing the light irradiation) is particularly advantageous

Side): Layer (B) - Layer (A) - Layer (C) or Layer (C) - Layer (B) - Layer (A). There are no particular restrictions with regard to the material of the clear layer (C); as a rule, however, it is advantageous to design the clear layer as a polymer or glass layer. In particular, layers made of transparent thermoplastics come into consideration as polymer layers. Particularly suitable transparent thermoplastics are polycarbonates or copolycarbonates or PMMA or PETG. For the optical properties of the layer system, it is advantageous if the same polymer as in the other layers is used in layer (C). In a layer system according to the invention, in which layers (A) and / or (B) are, for example, layers based on polycarbonate, it is advantageous if layer (C) is also a layer based on polycarbonate or PMMA or PETG.

Organic infrared absorbers which are suitable for use in the layer system according to the invention are compounds which have the highest possible absorption between 700 and 1500 nm (near infrared = NIR). Literature-known infrared absorbers, such as those used for. B. in M. Matsuoka, Infrared Absorbing Dyes, Plenum Press, New York, 1990 are described in terms of substance classes. Infrared absorbers from the classes of phthalocyanines, naphthalocyanines, metal complexes, azo dyes, anthraquinones, squaric acid derivatives, immonium dyes, perylenes, quaterylenes and polymethines are particularly suitable. Of these, phthalocyanines and naphthalocyanines are particularly suitable. Due to the improved solubility in thermoplastics, phthalocyanines and naphthalocyanines with bulky side groups are preferred. There are no particular restrictions with regard to the amount of organic infrared absorber contained in layer (A), as long as the desired absorption of heat radiation and sufficient transparency of the layer system is ensured. It has proven to be particularly advantageous if layer (A) contains organic infrared absorbers in an amount of 0.001 to 10 g / m ² , in particular 0.1 to 1 g / m ² . Depending on the extinction coefficient and layer thickness of the NIR / UV layer (layer A), the infrared absorbers are preferably used in concentrations between 1 and 10,000 ppm, preferably between 10 and 1,000 ppm and very particularly preferably between 20 and 400 ppm. Mixtures of infrared absorbers are also particularly suitable. The person skilled in the art can achieve an optimization of the absorption in the near infrared range with dyes of different wavelengths of the absorption maxima.

Ultraviolet absorbers suitable for use in the layer system according to the invention are compounds which have the lowest possible transmission below 400 nm and the highest possible transmission above 400 nm. Such compounds and their preparation are known from the literature and are described, for example, in EP 0 839 623 A, WO 96/15102 and EP 0 500496 A. Ultraviolet absorbers which are particularly suitable for use in the layer system according to the invention are benzotriazoles, triazines, benzophenones and / or arylated cyanoacrylates.

Particularly useful ultraviolet absorbers are hydroxy-benzotriazoles, such as 2- (3 ', 5'-bis (l, l-dimethylbenzyl) -2'-hydroxyphenyl) benzotriazole (Tinuvin ^® 234, Ciba Specialty Chemicals, Basel) 2- (2'-Hydroxy-5 '- (tert-octyl) phenyl) benzotriazole (Tinuvin ^® 329, Ciba Specialty Chemicals, Basel), 2- (2 ^, -hydroxy-3' - (2-butyl ) -5 '- (tert-butyl) phenyl) benzotriazole (Tinuvin ^® 350, Ciba Specialty Chemicals, Basel), bis- (3- (2H-benzotriazolyl) -2-hydroxy-5-tert-octyl ) methane, (Tinuvin ^® 360, Ciba Specialty Chemicals, Basel), 2- (hydroxy-2-hydroxyphenyl) -4,6-diphenyl-l, 3,5-triazine (Tinuvin ^® 1577, Ciba Specialty Chemicals, Basel), and that Benzophenone 2,4-dihydroxy-benzophenone (Chimasorb22 ^® , Ciba Specialty Chemicals, Basel), 2-propenic acid, 2-cyano-3,3-diphenyl-, 2,2-bis [[(2-cyano-l-oxo-3,3-diphenyl-2-propenyι) oxy] - methyl] -l, 3-propanediyl ester (9Cl) (Uvinul ^® 3030, BASF AG, Ludwigshafen). Mixtures of these ultraviolet absorbers can also be used.

Furthermore, nanoscale inorganic UV absorbers with or without organic UV absorbers can also be used. TiO ₂ , ZnO, CeO ₂ are preferred. The size of these particles is smaller than 100 nm. The production is known.

There are no particular restrictions with regard to the amount of ultraviolet absorber contained in the layer system, as long as the desired absorption of UV radiation and sufficient transparency of the layer system are ensured. According to a preferred embodiment of the invention, layer (A) contains ultraviolet absorbers in an amount of 0.1 to 10%, in particular 0.2 to 1%. It has also proven to be advantageous if layer (B) contains ultraviolet absorbers in an amount of 0.1 to 40%, in particular 1 to 10%.

There are no special restrictions with regard to the base material for layers (A) and (B) as long as the material has a high level of transparency and weather resistance and is therefore suitable for use in automotive glazing. However, it has proven to be particularly advantageous if the individual layers of the layer system are layers based on polymers or lacquers. This means that the organic infrared absorbers and / or ultraviolet absorbers, insofar as they are contained in the individual layers, are incorporated in a polymer or lacquer layer.

Transparent thermoplastic polymers are preferably used.

Transparent thermoplastic polymers in the sense of the invention are e.g. B. polymers of ethylenically unsaturated monomers and / or polycondensates of bifunctional reactive compounds. Examples of transparent thermoplastic Polymers are e.g. B. polycarbonates or copolycarbonates based on diphenols, poly- or copolyacrylates and poly- or copolymethacrylate such as. B. poly- or copolymethyl methacrylates and copolymers with styrene such as. B. transparent polystyrene-acrylonitrile (PSAN) or polymers based on ethylene and / or propylene and aromatic polyesters such as PET, PEN or PETG and transparent thermoplastic polyurethanes. Polymers based on cyclic olefins (eg TOPAS ^® , a commercial product from Ticona), poly- or copolycondensates of terephthalic acid such as, for. B. Poly- or copolyethylene terephthalates (PET or CoPET) or PETG can be mixed.

Mixtures of several transparent thermoplastic polymers are also possible.

Polycarbonates or copolycarbonates are preferred.

Particularly preferred polycarbonates are the homopolycarbonate based on bisphenol A, the homopolycarbonate based on 1,3-bis (4-hydroxyphenyι) -3,3,5-trimethylcyclohexane and the copolycarbonates based on the two monomers bisphenol A and 1.1 bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

Polycarbonates in the sense of the present invention are both homopolycarbonates and copolycarbonates; the polycarbonates can be linear or branched in a known manner.

The polycarbonates are prepared in a known manner from diphenols, carbonic acid derivatives, optionally chain terminators and branching agents.

Details of the production of polycarbonates have been laid down in many patents for about 40 years. For example, let's just look at Schnell, "Chemistry and Physics of Polycarbonates", Polymer Reviews, Volume 9, Interscience Publishers, New York, London, Sydney 1964, on D. Freitag, U. Grigo, PR Müller, H. Nouvertne ', BAYER AG, "Polycarbonates" in Encyclopedia of Polymer Science and Engineering, Volume 11, Second Edition, 1988, pages 648-718 and finally on Dres. U. Grigo, K. Kirchner and PR Müller "Polycarbonate" in Becker / Braun, plastic manual, volume 3/1, polycarbonates, polyacetals, polyesters, cellulose esters, Carl Hanser Verlag Munich, Vienna 1992, pages 117-299.

Diphenols suitable for the preparation of the polycarbonates are, for example, hydroquinone, resorcinol, dihydroxydiphenyls, bis (hydroxyphenyl) alkanes, bis (hydroxyphenyl) cycloalkanes, bis (hydroxyphenyl) sulfides, bis (hydroxyphenyl) ethers,

Bis (hydroxyphenyl) ketones, bis (hydroxyphenyl) sulfones, bis (hydroxyphenyl) sulfoxides, α-α'-bis (hydroxyphenyl) diisopropylbenzenes, and their core alkylated and nuclear halogenated compounds.

Preferred diphenols are 4,4'-dihydroxydiphenyl, 2,3-bis (4-hydroxyphenyi) propane, 2,4-bis (4-hydroxyphenyl) -2-methylbutane, 1,1-bis (4th -hydroxyphenyl) -p-diisopropylbenzene, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 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, 2,2- Bis (3,5-dichloro-4-hydroxyphenyl) propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3, 3, 5-trimethylcyclohexane.

Particularly preferred diphenols are 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis

(3,5-dimethyl-4-hydroxyphenyi) propane, 2,2-bis (3,5-dichloro-4-hydroxyphenyl) propane, 2,2-bis (3,5-dibromo-4 -hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane. These and other suitable diphenols are e.g. See, for example, US-A-3,028,635, US-A-2,999,825, US-A-3,148,172, US-A-2,991,273, US-A-3,271,367, US-A-4,982,014 and US-A-2,999 846, in DE-A 1 570 703, DE-A 2063 050, DE-A 2 036 052, DE-A 2 211 956 and DE-A 3 832 396, in FR-A 1 561 518, in the monograph “H , Schnell, Chemistry and Physics of Polycarbonates, Interscience

Publishers, New York 1964 "and in JP-A 62039/1986, JP-A 62040/1986 and JP-A 105550/1986.

In the case of homopolycarbonates, only one diphenol is used; in the case of copolycarbonates, several diphenols are used.

Suitable carbonic acid derivatives are, for example, phosgene or diphenyl carbonate.

Suitable chain terminators that can be used in the production of the polycarbonates are both monophenols and monocarboxylic acids. suitable

Monophenols are phenol itself, alkylphenols such as cresols, p-tert-butylphenol, p-n-octylphenol, p-iso-octylphenol, pn-nonylphenol and p-iso-nonylphenol, halophenols such as p-chlorophenol, 2,4-dichlorophenol, p-bromophenol and 2,4,6-tribromophenol, 2,4,6-triiodophenol, p-iodophenol, and mixtures thereof.

Particularly preferred chain terminators are p-tert-butylphenol and phenol.

Suitable monocarboxylic acids are also benzoic acid, alkylbenzoic acids and halobenzoic acids.

Preferred chain terminators are also the phenols of the formula (I)

wherein R is hydrogen or a C _\ to C ₃₀ -alkyl radical, is linear or branched, is preferably tert-butyl or is a branched or unbranched C ₈ and / or C -alkyl radical.

The amount of chain terminator to be used is preferably 0.1 to 5 mol%, based on moles of diphenols used in each case. The chain terminators can be added before, during or after phosgenation.

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

Suitable branching agents are, for example, phloroglucin, 4,6-dimethyl-2,4,6-tri- (4-hydroxyphenyl) -hepten-2, 4,6-dimethyl-2,4,6-tri (4-hydroxyphenyl) -heptane , 1,3,5-

Tri (4-hydroxyphenyl) benzene, 1,1,1-tri- (4-hydroxyphenyl) ethane, tri- (4-hydroxyphenyl) phenylmethane, 2,2-bis- [4,4-bis- (4-hydroxyphenyl) cyclohexyl] propane, 2,4-

Bis (4-hydroxyphenylisopropyl) phenol, 2,6-bis (2-hydroxy-5'-methylbenzyl) -4-methylphenol, 2- (4-hydroxyphenyl) -2- (2,4- dihydroxyphenyl) propane, hexa- (4 (4-hydroxyphenylisopropyl) phenyI) orthoterephthalic acid ester, tetra- (4-hydroxyphenyl) methane, tetra- (4- (4-hydroxyphenylisopropyl) phenoxy) methane and 1, 4-bis

(4 ', 4 "-Dihydroxytripehnyl) methyl) benzene and 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride and 3,3-bis (3-methyl-4-hydroxyphenyl) -2-oxo-2,3 dihydro indole.

The amount of branching agents which may be used is preferably 0.05 to 2 mol%, based in turn on moles of diphenols used in each case.

The branching agents can either be introduced with the diphenols and the chain terminators in the aqueous alkaline phase, or in an organic solvent. Solvent added before the phosgenation. In the case of the conversion process, the branching devices are used together with the diphenols.

The compositions according to the invention may also contain conventional polymer additives, such as. B. those in EP-A 0 839 623, WO 96/15102 and EP-A 0 500

496 described antioxidants and mold release agents, but also flame retardants, glass fibers, fillers, foaming agents, pigments, optical brighteners or dyes known in the literature, in the amounts customary for the respective thermoplastics. Quantities of up to 5% by weight, preferably 0.01 to 5% by weight, based on the amount of the compositions, particularly preferably 0.01 to 1, are preferred

% By weight, based on the amount of the compositions. Mixtures of several additives are also suitable.

The ion contents present in the thermoplastic polycarbonates as an impurity are preferably less than 10 ppm, particularly preferably less than 5 ppm.

The measures for producing the thermoplastic polycarbonates are familiar to the person skilled in the art.

In the case of several thermoplastic layers, the thermoplastic materials can be different or the same.

Suitable moldings / protective layer combinations are listed, for example, in EP 0 320 632 A. Similar plastics are preferably suitable.

Lacquer systems suitable for use in the layer system according to the invention are those whose crosslinking components have acrylate, allyl, epoxy, siloxane, isocyanate, anhydride and / or melamine formaldehyde functions. Comprehensive descriptions of such paint systems can be found in: “Textbook of paints and layers ", publisher: Dr. Hans Kittel, publishing house Hirzel, Stuttgart, 1998; in" Lackkunstharze "by Hans Wagner, Hans Friedrich Sarx, Carl Hanser publishing house Munich, 1971; especially for epoxy resins in "Epoxy Resins, Chemistry and Technology" edited by Clayton A. May and Yoshio Tanaka with Marcel Dekker, Inc. New York, 1973, Chapter 7, page 451 ff.

Siloxane paints such as, for. B. described in DE 4 020 316 A.

The thickness of the lacquer layers is 1 to 200 μm, preferably 2 to 50 μm and very particularly preferably 2 to 10 μm. The viscosity of the lacquer is preferably 5 to

10,000 mPa s.

Optionally, the polymers or lacquers used in layers (A), (B) and / or (C) may contain further additives, such as. B. the antioxidants, flame retardants, fillers described in EP 0 839 623 AI and EP 0 500 496 AI,

Foaming agents, conventional dyes and pigments, optical brighteners and nucleating agents or the like, preferably in amounts of up to 5% by weight, preferably 0.01 to 5% by weight, based on the mixture as a whole, particularly preferably 0.01 to 1 wt .-%, based on the amount of plastic. Mixtures of these additives are also suitable.

In addition, the thermoplastics can also contain conventional thermal stabilizers. As thermal stabilizers according to the invention are particularly suitable: hindered phenols such as octadecyl 3- (3 ', 5 ^t -di-tert-butyl-4'-hydroxyphenyl) propionate (Irganox ^® 1076, Ciba Specialty Chemicals, Basel, Switzerland). Furthermore, thermal stabilizers according to the invention particularly suitable phosphites, especially tris (2,4-di-tert-butyl-phenyl) phosphite (Irgafos ^® 168, Ciba Specialty Chemicals, Basel, Switzerland) or phosphines such. B. triphenylphosphine. The thermoplastics of the layer system according to the invention can also contain conventional mold release agents. Particularly suitable mold release agents are pentaerythritol tetrastearate (PETS) or glycerol monostearate (GMS).

The organic infrared absorbers, ultraviolet absorbers and other additives can be introduced into the individual layers of the layer system according to the invention by known methods such as compounding, mixing in solution, coextrusion, kneading, mixing in by injection molding or as a master batch.

The layer system according to the invention can by known methods such as painting,

Coextrusion, dipping, pressing, laminating, laminating, multi-component injection molding, application from solution, back injection or the like can be produced in one or more optionally different steps.

The application of the individual layers to each other can be done simultaneously or immediately after the shape of the grand body, z. B. by coextrusion or multi-component injection molding. The application can also be done on the molded base, z. b. by lamination with a film or by coating with a solution.

The layer structure according to the invention can optionally also subsequently be thermoplastic deformed, for example by deep drawing.

The layer system according to the invention can be produced, for example, by the following process steps:

(a) producing a composition for layer (A) by mixing organic infrared absorber and ultraviolet absorber with a transparent polymeric base material or coating system, (b) preparing a composition for layer (B) by mixing ultraviolet absorber with a transparent polymeric base material or coating system and

(c) Production of a layer system by coextrusion, injection molding or spraying on the layers (A) and (B) and optionally further layers.

The mixing of the ultraviolet and / or infrared absorber with the polymeric base material is preferably carried out by compounding.

According to a preferred embodiment of the invention, layer (A) is produced by injection molding, layer (B) by painting and optionally further layers by injection molding or painting.

The individual layers are preferably produced by coextrusion.

In addition to solid sheets, multi-wall sheets (double-wall sheets, three-wall sheets, etc.) or corrugated sheets can also be produced from the layer systems according to the invention. It is also used for injection molded parts such as food containers, components of electrical appliances and in glasses, e.g. B. also possible for goggles such as welding goggles.

The layer systems according to the invention can be used universally where heat permeability is undesirable. The application in automotive components, such as. B. glazing elements, car roof windows, plastic lenses and architectural applications such as building glazing, greenhouse components, skylights, bus stops or similar applications. The layer system according to the invention is suitable for the production of moldings, in particular for the production of transparent plastic glazing elements such as, for example, plastic glazing elements based on polycarbonate and / or copolycarbonate. The invention therefore also relates to moldings produced using the layer system according to the invention.

Examples

The invention is described in more detail below with the aid of exemplary embodiments.

example 1

To produce the test specimens, the polycarbonates (Makrolon 2808 or Makrolon ^® DP 1265 from Bayer AG, Leverkusen) with an average molecular weight of approx. 28,000 or 20,000 (M _w according to GPC) were used at 300 ° C on a twin-screw extruder with the The amount of additive stated in Table 1 was compounded and then granulated. Color sample plates are then sprayed from this granulate (60 mm x 40 mm x 2 mm). Compositions V5 and 6 were sprayed directly at 250 ° C.

The following compounds were used as IR absorbers:

IR absorber (A): vanadyl-5,14,23,32-tetraphenyl-2,3-naphthalocyanine (Aldrich, Steinheim, Germany),

IR absorber (B): copper (II) - 1,4,8,1 l, 15,18,22,25-octabutoxy-29H, 3 lH-phthalocyanine (Aldrich, Steinheim, Germany) and

IR absorber (C): KU3-2052 (commercial two-component NIR dye from Bayer AG, Leverkusen, Germany with the components

A and B). The following compounds were used as UN absorbers:

UV absorber (A): 2- (2'-hydroxy-3 ^, - (2-butyl) -5 ^, (tert-butyl) -ρhenyl) -benzotriazole (Tinuvin ^® 350 from Ciba Specialty Chemicals, Basel, Switzerland) and

UN absorber (B): bis- (3- (2H-benzotriazolyl) -2-hydroxy-5-tert.-oxtyl) methane

(Tinuvin ^® 360 from Ciba Specialty Chemicals, Basel, Switzerland).

Table 1

Composition of the samples

The color sample plates are then coated with a 100 μm thick polycarbonate film consisting of 5% UV absorber (B) in Makrolon ^® 3108 by pressing on at 155 ° C. and 100 kN for 60 s.

Example 2

The transmission spectra of the color sample platelets from the compositions 2, 4 and 6 and the comparative compositions 1, 3 and 5 were measured with a "lamda 9" UV-VIS-NIR spectrometer from Perkin Elmer. The samples are then measured with Xe-WOM below 0 , 35 W / m ² (102: 18) weathered and again the

Measure transmission spectra.

The transmission was measured at the absorption maximum in the NIR. In addition, in the case of compositions 2 and 4 and comparative compositions 1 and 3, the transmissions were measured at a secondary maximum in order to obtain a better comparison of the stabilizing effect of the layer system according to the invention.

Table 2

Transmission properties of compositions 2, 4 and 6, and of comparative compositions 1, 3 and 5 after 5,000 h Xe-WOM (Δ means T (5000) -T (0 h)

As can be seen from Table 2, the transmission at the absorption maxima or secondary maxima of the compositions 2, 4 and 6 according to the invention increases less than in the comparison compositions 1, 3 and 5. This means that the NIR dyes with the aid of The layer system according to the invention (compositions 2, 4 and 6) fades less during weathering than by protection only with a conventional UV protective layer (non-uniform compositions 1, 3 and 5). Example 3

The turbidity of weathered and unweathered samples was determined in accordance with ASTM D 1003 using the Haze-Gard device from BYK-Gardner

GmbH, D-82538 Geretsried.

Table 3

Turbidity tests and difference Δ of the turbidity before and after weathering for 3,000 h Xe-WOM

Δ = difference to the unweathered sample

The measured values in Table 3 show that the UV protective layer according to the invention (composition 6 with protective film) suffers only a 3.7% increase in haze, instead of 4.9% or even 21.3% or 27.4% in the comparison compositions , The absolute haze is also lower after weathering in the protective layer according to the invention. Example 4

The gloss of weathered and unweathered samples was determined in accordance with DIN standard 67530.

Table 4

glossy investigations

The measured values in Table 4 show that the layer system according to the invention (composition 2 with protective film), with 119% and 138%, exhibits a higher gloss after 5,000 h of Xe-WOM than comparison samples, which were in some cases weathered for less time.

The test results show that the layer systems according to the invention with simple construction have excellent long-term weather stability with Xe-WOM weathering, even after 5,000 hours, excellent transparency behavior and excellent gloss values.

Claims

Patent claims

1. Transparent heat-absorbing layer system, containing a first layer (A) and a second layer (B), the first layer (A) having at least one organic infrared absorber and at least one ultraviolet absorber.

Absorber and the second layer (B) contains at least one ultraviolet absorber and the first layer (A) is the only layer in the layer system that contains an organic infrared absorber.

2. Layer system according to claim 1, characterized in that the first

Layer (A) has a thickness of 0.8 to 15 mm, in particular 3 to 6 mm.

3. Layer system according to one of the preceding claims, characterized in that the second layer (B) has a thickness of 1 to 100 μm.

4. Layer system according to one of the preceding claims, characterized in that the second layer (B) is designed as a polymer film with a thickness of 30 to 80 μm, in particular 40 to 60 μm.

5. Layer system according to one of the preceding claims, characterized in that the second layer (B) is designed as a lacquer with a thickness of 1 to 10 μm, in particular 4 to 6 μm.

6. Layer system according to one of the preceding claims, characterized in that in addition to the layers (A) and (B), at least one further transparent layer (C) is present in the layer system, which contains neither infrared nor ultraviolet absorbers.

7. Layer system according to claim 6, characterized in that the transparent layer (C) contains a polymer and / or a glass.

8. Layer system according to one of the preceding claims, characterized in that the first layer (A) contains an organic infrared absorber

Amount of 0.001 to 10 g/m ² , in particular 0.1 to 1 g/m ² .

9. Layer system according to one of the preceding claims, characterized in that the first layer (A) contains ultraviolet absorbers in an amount of 0.1 to 10%, in particular 0.2 to 1%.

10. Layer system according to one of the preceding claims, characterized in that the second layer (B) contains ultraviolet absorbers in an amount of 0.1 to 40%, in particular 1 to 10%.

11. Layer system according to one of the preceding claims, characterized in that the infrared absorber is selected from the group of phthalocyanines and naphthalocyanines.

12. Layer system according to one of the preceding claims, characterized in that the ultraviolet absorber is selected from the group of benzotriazoles, triazines, benzophenones and arylated cyanoacrylates.

13. Layer system according to one of the preceding claims, characterized in that the layers (A) and (B) are based on polymer and/or layers

varnish base.

14. Layer system according to claim 13, characterized in that a transparent thermoplastic, in particular a polycarbonate or a co-polycarbonate, is used as the polymer.

15. Layer system according to claim 13, characterized in that the lacquer is selected from the group of acrylate, allyl, epoxy, siloxane, isocyanate, anhydride and melamine formaldehyde crosslinked lacquers.

16. Layer system according to claim 15, characterized in that the lacquer is a siloxane lacquer.

17. Method for producing a layer system according to points 1 to 16, characterized by the following steps:

(a) producing a composition for layer (A) by mixing organic infrared absorbers and ultraviolet absorbers with a transparent polymeric base material or lacquer system,

(b) preparing a composition for layer (B) by mixing ultraviolet absorber with a transparent polymeric base material or lacquer system

(c) producing a layer system by coextrusion, injection molding or

Spraying on the layers (A) and (B) and, if necessary, one or more clear layers (C).

18. The method according to claim 17, characterized in that the mixing is carried out by compounding.

19. Method according to points 17 or 18, characterized in that layer (A) is produced by injection molding, layer (B) by painting and layer (C) by injection molding or painting.

20. The method according to any one of claims 17 to 19, characterized in that the layers (A) and (B) and optionally (C) are produced by coextrusion.

21. Shaped body containing a layer system according to one of claims 1 to

16.

22. Shaped body according to address 21, characterized in that the shaped body is a transparent plastic glazing element, in particular a transparent plastic glazing element based on polycarbonate and / or

Copolycarbonate is.

23. Use of a layer system according to one of claims 1 to 16 for heat radiation shielding of plastic glazing elements.