WO2009103375A1

WO2009103375A1 - Multi-wall sheets with photosynthetically active radiation

Info

Publication number: WO2009103375A1
Application number: PCT/EP2008/067157
Authority: WO
Inventors: Wolfgang Scharnke; Volker Mende
Original assignee: Evonik Röhm Gmbh
Priority date: 2008-02-22
Filing date: 2008-12-10
Publication date: 2009-08-27
Also published as: TW200950965A

Abstract

The invention relates to transparent multi-wall or solid sheets, containing IR reflectors, possibly IR absorbers, carbon black and colourant, and to use thereof as a heat-insulating and sun-shielding roofing and glazing material.

Description

Multiwall sheets with photosynthetically active radiation

The invention relates to translucent web plates containing pigments with high scattering power and high light transmission and reduction of the IR radiation, its use as roofing and glazing material, in particular for greenhouses.

State of the art

Transparent, IR-absorbing bodies made of plastics are available in different

Patents described. EP 927741 describes thermoplastics containing a copper dithiocarbamate compound which can be injection molded.

JP 10157023 discloses thermoplastics that are IR absorbing

Dithiolmetallkomplexe included.

EP 607031 and JP 06240146 describe thermoplastic materials which

Contain IR-absorbing phthalocyanine metal complexes.

JP 61008113 discloses IR-absorbing adhesive sheets which can be applied to glazings.

JP 56129243 and EP 19097 disclose plastic sheets of methyl methacrylate which contain organic copper phosphate complexes as the I R absorber.

WO 01/18101 describes molding compositions containing IR-absorbing dyes. The molding compositions are also suitable, inter alia, for the production of cavity plates, double-skin sheets or multi-layer sheets, which may optionally also be provided with one or more coextruded layers. In such an embodiment, the entire shaped body contains the IR-absorbing pigment. This has the disadvantage that the absorbed heat heats the entire plastic body and the heat is unspecifically discharged in all directions.

WO 03/013849 describes plastic bodies with low thermal conductivity, high light transmission and absorption in the near infrared range. The plastic body, consist of a basic form body, which is made of a transparent thermoplastic resin base material, and which consists of at least two opposite planar layers which are interconnected by vertical or diagonally arranged webs, wherein one of the sheet-like layers with an additional Layer is provided of a plastic matrix of transparent plastic base material, characterized in that the additional layer is an IR-absorbing layer containing one or more, the transparency of the plastic body does not adversely affecting IR absorber, which in the range of near infrared radiation (780nm up to 1100 nm) has an average transmission of less than 80%, the plastic body a light transmission (D65) of 15 to 86%, a heat transfer coefficient of 4 W / m ² K or smaller and an SK number of 1, 15 or greater having.

Task and solution

It should thus be provided a plastic body which is translucent and has a more pleasant color tone. At the same time, the solar energy should be used by photosynthetically active radiation (PAR 400-700 nm) can pass through the plastic body, overheating is avoided by too much near IR radiation (NIR). The PAR / NIR ratio should be <1.

The object is achieved by a translucent plate consisting of a solid plate, web double or multiple plate made of transparent thermoplastic material, containing light-scattering pigment particles with high light transmission and simultaneous reduction of the IR component (780 nm to 1100 nm) of the sunlight spectrum.

It has been found that the use of light-scattering pigment particles and optionally the use of the transparency of the plastic body does not adversely affect the IR absorber, the solar energy for the growth of plants can be ideally used. The light-scattering pigment particles lead to a sufficient supply of photosynthetically active radiation (PAR), at the same time they act as IR reflectors. These IR reflectors and optionally added IR absorber cause that only greatly reduced near infrared radiation can pass through the Masiv- or web plate and thus the solar energy leads to much lower heating on the side facing away from the sun.

Compared to the known plastic bodies according to the

WO 03/013849, a particular embodiment of the present invention differs in that in addition a mixture of a carbon black and colorants is included, so that the plastic body has an appealing shade of gray. Although the measures result in that the SK number is in contrast to WO 03/013849 under 1, 15, it was surprisingly found in a practice-oriented test that the temperature rise on the opposite side of the plastic body when exposed to light (greenhouse effect) in a similar manner is reduced as in plastic bodies according to WO 03/013849. The invention is therefore also based on the finding that the selectivity index according to DIN 67507 (SK number) is only a limited suitable control variable for the development of IR absorber-containing plastic body, which should have a reduced greenhouse effect. A more suitable benchmark for the reduction of the greenhouse effect in comparison to the SK number may be the total energy transmission coefficient g (DIN 67507) or the so-called "Solar Heat Gain Coefficient" (SHGC, ISO 15099.) Both quantities correlate relatively well (g = 0.86 However, the consideration of g or SHGC can not completely reproduce the overall impression. In the case of the solid plates, web double or multiple plates according to the invention, the transmission is in comparison to plates not according to the invention clearly, the total energy transmission coefficient only slightly reduced. Nevertheless, the plastic body according to the invention appear to the unbiased viewer in the review unexpectedly bright.

Embodiment of the invention

The invention relates to solid or web double or multiple plates, which are characterized by a particularly simple structure. A conventional solid plate, bar double or multiple plate according to the invention is provided with light-scattering pigmets and optionally with an IR absorber layer. As a result, solar energy is reflected or absorbed, which leads to the reduction of heat energy on the side of the web plate remote from the sun. Accordingly, the solid or web double or multiple web plate according to the invention also fulfills the object of thermal insulation.

The incorporation of the functional layer in the interior of the web double or - multiple plate also has the advantage that this layer is protected from the weather and mechanical influences.

Ideally, the plate according to the invention can be used directly as a greenhouse cover or other translucent roofing.

The invention relates to solid plates, web double or web multiple plates with pigment particles that emit photosynthetically active radiation and absorb a substantial portion of near infrared radiation (NIR) in the range of 0.7 to 1, 5 microns.

The invention also relates to solid plates, web double or multiple plates consisting of a transparent thermoplastic material containing one or more, the transparency of the plastic body not affecting IR Absorber, which has an average transmission of less than 80%, preferably less than 75 in the range of near infrared radiation (780 nm to 1100 nm).

In addition, a mixture of a carbon black and colorants may be included, so that the plastic body or possibly only portions of the plastic body a gray tone based on the Cie-Lab color space within L * corresponding to the specified light transmission range, eg. B. L * in the range 10 to 75 or 30 to 75, as well

a ^* = +/- 5.0, preferably -5.0 to -0.5, more preferably -3.0 to -2.0, and

b ^* = +/- 5.0, preferably 1, 0 to 5.0, particularly preferably 3.0 to 4.5.

The plastic body has an SK number of less than 1, 15, in particular less than 1, 1, z. B. 1, 0 to 1, 1 or optionally 0.8 to 1, 1 on.

In the chemical industry, as well as in the glass industry, two color systems or color spaces are used, in particular, to give the impression of colored plastics or glasses. These are the standard color chart and the Cie-Lab color space, which are described in detail in DIN 5033, Part 2, 3 and 7, as well as in DIN 5036, Part 1.

The Cie-Lab color space allows, in contrast to the two-dimensional standard color chart to make color comparisons and to measure the distance to target colors. The size L ^* indicates the brightness (leightness) and correlates approximately with the transmittance of a plastic body to be measured. L ^* in the range 10 to 75 correlates roughly with light transmission (D65) of 15 to 70%. The size a * indicates the red-green chroma, the size b * the yellow-blue chroma. The color space L * in the range or equal to 10 to 75, a * = +/- 5.0 and b * = +/- 5.0 is therefore a transparent plastic body with a shade of gray. Depending on the location of a * and b * may be the gray tone a slight hint (Stichigkeit) to the Red, Green, Yellow or Blue ^* = 0 have also fail completely neutral or a ^* and b.

The plastic body may have a light transmittance (D65, DIN 67 507, light _{transmittance} for daylight (standard _illuminant D65) _DΘS SZB also DIN 5033/5036) of 15 to 70, preferably from 25 to 50%.

The plates according to the invention are realized by means of a hollow-chamber plate, in particular a double-walled plate, a multi-plate plate, in particular a web triple plate or a quadruple plate.

The hollow chamber plate may consist of at least two layers which are not firmly connected and / or are firmly connected by coextrusion or by lamination or by painting.

Hollow chamber plates or web plates consist of two opposite flat layers, the outer straps, the upper and lower straps, which are interconnected by vertical or diagonally arranged webs. The laminar layers are preferably parallel to each other. In a double-walled plate z. B. are two parallel belt layers, namely the upper and lower flange, with corresponding webs before. A web trough panel also has an intermediate belt arranged parallel to the upper and lower belt. Intermediate straps lie in the interior of the plate in contrast to the upper and lower straps. In a truss bridge plate, the webs may be at least partially arranged diagonally.

In the case of solid sheets, the pigment particles are preferably in the co-extruded layers, in the case of web double or multi-layer sheets preferably in the laid-up, coextruded, laminated and / or lacquered layer. This layer may or may not contain soot and colorant. The optionally used IR absorber is expediently in the applied, coextruded, laminated and / or lacquered layer. This layer may or may not contain soot and colorant.

In the case of a multilayer plastic body, the pigment particles and optionally the IR absorber are preferably located in a layer, eg. B. an inner, thin coextruded layer, while soot and colorants are in another layer, in particular in the underlying base molding.

A further preferred embodiment is a hollow chamber plate, in particular a double-walled plate, a multi-plate web, in particular a web triple plate or a web quadruple plate, in which one or optionally both straps and the remaining web plate are coextruded, wherein at least one coextruded belt, the IR absorber, and carbon black and colorants contains. The rest of the web plate can z. B. colorless or, to ensure a uniform color impression, carbon black or carbon black and colorants. Particularly preferably, the web plate consists of impact-modified poly (meth) acrylate. The coextrusion of a complete outer belt has the advantage that the layer has sufficient thickness or thickness, for. B. from 0.5 to 2 mm, which allows it to be used with good distribution in the extrusion die a plastic molding compound of approximately the same or the same melt viscosity as for the basic form body. In particular, the same plastic molding compound can be used for both layers. This has the advantage in a web plate made of impact-modified poly (meth) acrylate, that the hail impact resistance of the coextruded belt layer is not less than that of the base mold body. This would inevitably be the case with very thin coextrusion layers, which require the use of a low-viscosity molding compound for reasons of distribution of the melt in the extrusion die.

The preferred way to place the pigment particles and optionally the IR-absorbing layer is in the context of a continuous coextruded inner coating of one or both belts. A corresponding extrusion tool for the inner coating of the belt surfaces of web plates is known from EP 1 270 176 A.

Typical dimensions for multi-wall sheets are: Thickness of the upper and lower chords for multi-wall sheets: approx. 0.4 to 3 mm Thickness of the intermediate chords and webs for multi-wall sheets: approx. 0.1 to 2 mm. Lengths: up to approx. 6000 mm or more (if necessary cut to length)

materials

The solid plates or web plates consist essentially of a transparent thermoplastic plastic base material, which has a z. Example, a polymethyl methacrylate plastic, a toughened polymethyl methacrylate (see, for example, EP-A 0 733 754), a polycarbonate plastic (branched or linear polycarbonate), a polystyrene plastic, styrene-acrylonitrile plastic, a Polyethylene terephthalate plastic, a glycol-modified polyethylene terephthalate plastic, a polyvinyl chloride plastic, a transparent polyolefin plastic (e.g., producible by metallocene-catalyzed polymerization), or an acrylonitrile-butadiene-styrene (ABS) plastic. It can also consist of combinations or blends of various thermoplastics.

A transparent thermoplastic material or plastic base material has, without pigment particles, IR absorber, carbon black and colorants, for. B. a light transmission (D65) of 15 to 92, preferably 65 to 90%.

For certain applications, eg. B. if glare is to be avoided by very intense solar radiation, the transparent thermoplastic resin base material also another scattering agent, for. B. BaSO ₄ , z. B. in amounts of 0.5 to 5 wt .-%, or another light scattering agent, for. B. light scattering beads be added, whereby the originally transparent plastic light scattering, translucent.

Lichtstreuperlen can z. B. in concentrations of 0.1 to 30 wt .-%, preferably 0.5 to 10 wt .-% are added. Crosslinked light scattering beads of copolymers of methymethacrylate and styrene or benzyl methacrylate, which are particularly suitable for basic molded articles made of polymethyl methacrylate are, for. B. known z. Example from DE 35 28 165 C2, EP 570 782 B1 or EP 656 548 A2.

The pigment particles

Functional pigments are particulate, practically insoluble in the application medium, which are used as colorants or because of their corrosion-inhibiting, magnetic, electrical or electromagnetic properties. In addition to conventional functional pigments, new pigments have been developed and launched based on the layer-substrate principle. The substrate used in most cases is mica in the form of thin platelets, while the layers on the mica platelets consist of metal oxides which are carriers of the functional properties. Merck, Darmstadt sells various mica-based pigment types. The family of Solarflair ™ pigments are able to reflect heat. They reflect the invisible heat radiation of sunlight, but are permeable to the visible part of the light.

Preference is given to using pigments of the Solarflair ™ group, particularly preferably Solarflair 9870. Pigments in quantities of 0.625 to 12.5 g / m ² are used.

The IR absorbing layer

The layer thickness of the inner, thin layer is z. B. in the range of 2 to 250 microns. The layer thicknesses of coextruded layers are preferably in the range from 5 to 250, preferably from 20 to 150, in particular from 50 to 125 μm.

The layer thicknesses of laminated layers are preferably in the range of 10 to 250, preferably 10 to 100 microns.

The layer thicknesses of coated layers after drying are preferably in the range from 2 to 50, preferably from 5 to 25 μm.

The IR-absorbing layer may additionally comprise a UV absorber in conventional concentrations, eg. B. 0.1 to 15 wt .-%, to protect the IR absorber and the plastic matrix from degradation by UV radiation. The UV absorber may be a volatile, low molecular weight, slightly volatile, high molecular weight or polymerizable UV absorber (see, for example, EP 0 359 622 B1).

The plastic matrix of the IR absorbing layer is made of transparent plastic base material which may be thermoplastic, thermoelastic or crosslinked. Preferably, the plastic base material of the IR absorbing layer of the same type of transparent, thermoplastic plastic base material, which also consists of the basic form body, so z. Example of a polymethyl methacrylate plastic, a toughened polymethyl methacrylate plastic, a polycarbonate plastic (branched or linear polycarbonate), a polystyrene plastic, a polyethylene terephthalate plastic or an acrylonitrile-butadiene-styrene (ABS) plastic.

In this case, the base molding z. B. consist of a more viscous variant of a plastic type, z. Polymethyl methacrylate, and the plastic matrix of a lower viscous variant of the same type, e.g. B. a low-viscosity polymethylmethacrylate, z. B. is particularly well suited for coextrusion.

Due to the presence of the IR absorber, the outer layer and thereby the entire plastic body appears greenish to bluish turquoise, depending on the IR absorber used. In cases where you want to avoid or mitigate this color impression, can be a light-scattering pigment, eg. B. a white pigment, z. As barium sulfate, in amounts of 0.5 to 5 wt .-% enforce. This has the technical advantage that the glare effect in translucent sun is mitigated by the light is scattered. Optionally, a compensation of the color impression can be achieved by adding dyes.

For certain applications, eg. B. if glare is to be avoided by very intense solar radiation, the transparent plastic base material of the additional layer, a scattering agent, for. B. BaSO ₄ or another light scattering agent, for. As Lichtstreuperlen be added, whereby the original transparent plastic light scattering, translucent, is.

Optionally, on the additional layer of transparent plastic, which contains an IR-absorbing layer, one or more further z. B. coextruded, painted or laminated layer of plastic, preferably transparent plastic. In this case, the IR-absorbing layer is not outside but inside the outer layer of the plastic body. The further or the further layers can have different functions, eg. B. mechanical protection of the IR-absorbing layer, z. As a scratch-resistant coating, anti-graffiti coating, UV absorber layer, pigment-containing layer to effect a color impression etc .. Preferably, the layer thicknesses of the other layers are in the range of 2 to 200, preferably from 5 to 60 microns.

It can, for. B. be useful in the case of a web plate made of polycarbonate on the IR absorber layer nor an additional z. Coextruded layer which contains a UV absorber and protects the polycarbonate from premature weathering (polycarbonate web sheets with additional UV absorber layer are known, for example, from EP 0 359 622 B1). The UV absorber may be a volatile, low molecular weight, slightly volatile, high molecular weight or a polymerizable UV absorber and in a layer with a layer thickness z. B. in the range 2 to 100 microns in a concentration of z. B. 0.01 to 15 wt .-% may be included. The IR absorber

The use of the IR-absorbing compounds suitable for carrying out the invention as an additive to various thermoplastics is known in principle (see prior art).

The additional layer contains an IR absorber which does not impair the transparency of the plastic body. This means that the plastic body remains clearly transparent in the presence of the contained IR absorber. This is possible because the IR absorber in the plastic matrix of the additional layer is quasi-soluble or copolymerized. Since soluble IR absorbers are relatively high molecular weight, there is generally no migration into underneath or optionally overlying plastic layers.

The IR absorber may be an organic Cu (II) phosphate compound. Preferably z. Example, an organic Cu (II) phosphate compounds, which can be obtained from 4 parts by weight Phosphorsäuremethacryloyloxyethylester (PMOE) and one part by weight of copper (II) - carbonate (KCB).

Suitable are z. As organic Cu (II) phosphate complexes, such as. In JP 56129243 or EP 19097. These compounds may, for. B. be used as co-monomers in Polymehsierenden paint layers of polymethyl methacrylate plastic. Due to their cross-linking effect, they also provide increased scratch resistance of the plastic surface.

The IR absorber may be a phthalocyanine derivative. Preference is given to phthalocyanine derivatives such as. As described in patents EP 607,031 and JP 06240146. The IR absorber may be a perylene Dehvat or z. B. be a Quaterrylentetracarbonsäureimid compound such. As described in EP 596 292.

Preferably, the non-crosslinking compounds, as these z. B. for the coextrusion process or for application in non-polymerizing paints that cure after evaporation of a solvent by itself. The application of an IR-absorbing layer by lamination with prefabricated films has the advantage that the film production generally allows a more uniform layer thickness distribution. Laminated film layers containing the IR absorber are usually more uniform than corresponding coextruded layers. High molecular weight IR absorbers or polymerized IR absorbers have the advantage of being particularly migration stable, i. they do not migrate at high manufacturing or service temperatures or in the course of their useful life practically in the underlying or possibly overlying plastic layers.

The above-mentioned IR absorber types can, for. B. in a coextruded or laminated plastic matrix in a concentration of 0.01 to 5, preferably from 0.05 to 2, in particular 0.1 to 0.5 wt .-%.

In polymerizing paint systems, the concentration z. B. 0.1 to 5 wt .-% based on the paint dry substance.

In non-polymerizing coating systems, the concentration z. B. 0.2 to 5% by weight based on the paint dry substance.

A preferred IR absorber is lanthanum hexaboride (LaB ₆ ). This IR absorber is already effective in very low concentrations.

Lanthanum hexaboride (LaB ₆ ) can be found in a z. B. concentration of 0.0005 to 0.1, preferably 0.005 to 0.08 wt .-% are present. Commercially available lanthanum hexaboride Preparations which may contain from about 10 to 30% by weight of lanthanum hexaboride, 15 to 35% by weight of zirconium oxide and 40 to 60% by weight of organic dispersing agents are suitable for the purposes of the invention.

Selectivity index (SK number, T / g according to DIN 67 507)

The ratio between light transmittance (T) and total energy transmittance (g) is less than 1, 15, in particular less than 1, 1, z. B. 1, 0 to 1, 1 or optionally 0.8 to 1, 1. The total energy transmittance (g) describes the proportion of the energy of solar radiation passing through the body. It is composed of directly transmitted radiation and a heat fraction generated by absorption. A high level of thermal insulation can be achieved in that the body consists of at least two solid layers, which are thermally decoupled by air chambers. The layers are interconnected in web plates by thin webs. The IR-absorbing layer preferably consists of a coating layer of a transparent plastic which adheres to the base material and contains one or more IR-absorbing compounds. Concentration of the IR-absorbing compound and layer thickness of the coating layer are preferably z. B. to be chosen so that the maximum of the absorption in the range between 780 and 1100 nm at least 25%, in particular at least 50%. The average absorption in the range between 780 and 1100 nm can z. B. preferably at least 10, more preferably at least 20, in particular at least 25%. In the case of a multiple-wall plate, the heat transfer coefficient according to DIN 52612 may be less than or equal to 4, preferably 3 to 1.5 W / m ² K.

use

The translucent solid plates according to the invention, web double or multiple web plates can be used as a glazing, roofing or thermal insulation element. Equipped with pigments Planting foils with a limited shelf life of 2-4 years, the solid plates or web plates according to the invention for greenhouse construction can be used. The life of these plates can be further increased by appropriate additives. The RESIST ^® multi-wall sheets sold by the company Röhm, Darmstadt show an increased weather resistance. The ALLTOP ^® multi-wall sheets are equipped with water-spreading surfaces, which also increase the service life of multi-wall sheets in horticulture. According to the invention, weather-resistant or water-spreading surface-modified webs are processed with SOLAFLAIR ™ pigments into transparent panels with a PAR / NIR ratio> 1.

Advantages of the invention

The energy content of the light in the solar radiation is about 50%, the UV radiation content is about 5% and about 45% is attributable to the NIR radiation. All three types of radiation contribute to the heating of glazed rooms. Prior art thermal barrier glazings are based on either reflection or solar radiation absorption.

Simple systems reduce the overall energy transmittance by reducing radiation transmission over the entire solar radiation range (from 300 nm to 2500 nm). Carbon black pigments absorb the radiation in this area and thus reduce the total energy transmittance depending on the layer thickness or concentration. As a result, the light transmission is also reduced. The selectivity index, which describes the ratio of light transmission to total energy transmittance, is therefore no greater in these systems than standard glazes, or even worse in the case of carbon black pigments. However, there are applications such as greenhouses where a high selectivity index is beneficial. A high selectivity index is achieved by selective, high transmission in the visible wavelength range between 380 nm and 780 nm and shielding against IR radiation (> 780 nm) and UV radiation (<380 nm). This selectivity is generated by interference in reflective systems. Either you vaporize the Surfaces with layers of different refractive indices at submicrometer layer thicknesses, or pigments which already contain such interference layers. The evaporation of the surface is technically very complicated and the use of the pigments leads to a strong scattering of the radiation, whereby the transparency is lost. Absorbent systems use substances that have a low absorption in the visible range and a high absorption in the NIR range.

A disadvantage of these systems is that the absorbed radiation leads to a heating of the glazing body. The solar radiation, consisting of UV, VIS and NIR radiation impinges on the glazing. The essential part of the radiation in the visible range is transmitted. The proportion of radiation absorbed by the glazing is emitted as long-wave heat radiation to the outside (q _a ) and to a slight extent inside (q,). By exploiting the convection ratios according to the invention, substantially more heat is released to the outside than to the inside.

The portion of the long-wave heat radiation that is emitted inwardly into the room contributes to the overall energy transmittance. Another advantage of the invention lies in the ease of manufacture of the plastic body. In the co-extrusion process, in a continuous process, multi-web plates of low k value can be directly provided with a topcoat containing the IR absorber.

Light transmittance, total energy transmittance and selectivity index

The degree of transmission of light and the total energy transmittance are dependent on the type, concentration and layer thickness of the IR absorber in the cover layer as well as on the base body. The appropriate light transmission level depends on the application. In greenhouses, it should be very high, as it has a direct influence on the yield. For roofing of pedestrian passages or large-area glazing in air-conditioned buildings is rather a very low Total energy transmittance important. By further incorporation of carbon black pigments or other colorants in the topcoat that absorb in both the visible and NIR ranges, the light transmission and, likewise, the total energy transmittance can be further reduced. The minimum light transmission should be at least 30%. For non-dyed double skin plates as a base body, the max. Light transmission up to 86%. In the case of uncoated web plates, the selectivity index is about 1, SK-numbers of a similar size were determined on systems coated on one side in the sense of the invention.

The plastic body has z. Example, the shape of a multi-web plate, consisting of at least two parallel plastic layers which are interconnected by vertically or diagonally arranged webs. Typical thicknesses for the two outer plates are between 0.2 mm and 5 mm, preferably between 0.5 mm and 3 mm. Typical thicknesses for any existing inner plates are between 0.05 and 2 mm, preferably between 0.1 mm and 1 mm. In order to achieve effective thermal insulation, the distance between the plates should be at least 1 mm, preferably more than 4 mm. The web thickness should be between 0.2 mm and 5 mm, preferably between 0.5 mm and 3 mm. The suitable web spacing is between 5 mm and 150 mm, preferably between 10 mm and 80 mm. The body should be designed in its entirety so that the heat transfer coefficient k according to DIN 52619 is less than 4 W / m ² K, preferably less than 3 W / m ² K. The base material consists of a transparent plastic, suitable for this purpose for example being a polymethyl methacrylate plastic, an impact-modified polymethyl methacrylate (see, for example, EP-A 0 733 754), a polycarbonate plastic (branched or linear polycarbonate), a polystyrene plastic , Styrene-acrylonitrile plastic, a polyethylene terephthalate plastic, a glycol-modified polyethylene terephthalate plastic, a polyvinyl chloride plastic, a transparent polyolefin plastic (for example producible by metallocene-catalyzed polymerization) or an acrylonitrile-butadiene-styrene ( ABS Plastic. It can also consist of mixtures (blends) of various thermoplastics. Under polymethylmethacrylate are in the sense The invention is understood to mean rigid amorphous plastics which are composed of at least 60% by weight, preferably at least 80% by weight, of methyl methacrylate. The polycarbonate plastics are predominantly aromatic polycarbonates of bisphenols, in particular of bisphenol A.

Soot and colorants

Preference is given to using carbon black, particularly preferably a carbon black, having an average particle size in the range from 10 to 20 μm.

The carbon black is preferably added to colorants which have a lower absorption maximum in the wavelength range from 650 to 750 nm than in the wavelength range from 250 to <650 nm.

The colorants are different from the used I R absorber and usually not even IR-absorbing. There are all colorants alone or in mixture into consideration, with their help together with the IR absorber and the Russ a corresponding gray-tinted coloration of the plastic body, or the colored part of the plastic body in the Cie-Lab color space of L ^* = 10 to 75, a ^* = +/- 5.0 and b ^* = +/- 5.0 can be achieved. It can z. B. Colorants from the commercially available dye series Thermoplast® (BASF), Macrolex® (Bayer), Sandoplast® (Clariant) or Oracet® (Ciba)

Macrolexgrün® 5B (green colorant based on anthraquinone with the Color Index Solvent Green 3) and Plast Red® 8350 (red colorant based on anthraquinone with the Color Index Disperse Red 22) may preferably be added as the colorant. The content of carbon black and colorants together may be 0.001 to 0.15, preferably 0.05 to 0.1 wt .-% .-%, based on the colored therewith layer of the plastic body.

EXAMPLES

example 1

Test System:

Plant cultures were covered with different sample plates and the

Plant growth assessed under the same conditions.

As sample plates were double-walled sheets of PMMA with different proportions

Pigment Solarflair ™ used in the harness and various proportions in the compound.

The results are summarized in Table 1:

Table 1

Claims

1. Translucent plates consisting of a web double or - multiple plate or solid sheets of transparent thermoplastic material, containing light-scattering pigment particles with high light transmission and simultaneous reduction of the IR component (780nm to 1100 nm) of the sunlight spectrum.

2. Translucent panels according to claim 1, characterized in that the plastic body consists essentially of one, optionally of a combination or mixtures of the following plastics: polymethyl methacrylate plastic, impact modified polymethyl methacrylate, polycarbonate plastic, polystyrene plastic, styrene acrylic Nithl plastic, polyethylene terephthalate plastic, glycol-modified polyethylene terephthalate plastic, polyvinyl chloride plastic, transparent polyolefin plastic, acrylonitrile-butadiene-styrene (ABS) plastic or mixtures (blends) of various thermoplastics.

3. Translucent panel according to claim 1, characterized in that it consists of one or more plastic layers

4. Translucent panel according to claim 1, characterized in that it consists of at least two layers that are not firmly connected and / or firmly connected by coextrusion or by lamination or by painting.

5. Translucent plate according to claim 1, characterized in that it is a hollow chamber plate, in particular a double-walled plate, a multi-plate plate, in particular a web triple plate or a Stegvierfachplatte is in which one or optionally both outer straps and the rest of the moldings are coextruded, wherein at least one coextruded belt contains the IR reflector in the near IR range, and optionally IR absorber, carbon black and colorant.

6. Translucent panel according to claim 1, characterized in that it consists of impact-modified poly (meth) acrylate.

7. Translucent panel according to claim 1, characterized in that the IR reflector, and optionally IR absorber, carbon black and colorants are next to each other in the same plastic layer.

8. Translucent panel according to claim 1, characterized in that in the case of a multilayer plastic body, the IR reflector in a layer and optionally IR absorber, carbon black and colorants are in another layer.

9. Translucent panel according to claim 1, characterized in that the IR-reflecting layer additionally contains a UV absorber.

10. Translucent panel according to claim 1, characterized in that are added as colorant Macrolexgrün® 5B and Plast Red® 8350.

11. Translucent panel according to claim 1, characterized in that the content of carbon black and colorants together may be 0.001 to 0.15 wt .-%, based on the thus colored layer of the plastic body.

^. Translucent panel according to claim 1, characterized in that the IR reflector is a pigment SOLARFLAIR ™ 9870 from Messrs. Merck, Darmstadt.

13. Translucent plate according to claim 1, characterized in that the IR absorber is an organic Cu (II) phosphate compounds.

14. A translucent panel according to claim 13, characterized in that the organic Cu (II) phosphate compound is a phosphoric acid methacryloyloxyethyl ester / copper (II) complex.

15. Translucent plate according to claim 1, characterized in that the IR absorber is a phthalocyanine derivative.

16. Translucent panel according to claim 1, characterized in that the IR absorber is a Quaterrylentetracarbonsäureimid compound.

17. Translucent plate according to claim 1, characterized in that the IR absorber is lanthanum hexaboride (LaB ₆ ).

18. Translucent panel according to claim 17, characterized in that the lanthanum hexaboride (LaB ₆ ) is present in a concentration of 0.0005 to 0.1 wt .-%.

19. Use of a translucent web or solid plate according to claim 1 as glazing, roofing or thermal insulation element.