Flat element having a dark surface exhibiting a reduced solar absorption

The flat element having a dark surface and exhibiting a reduced solar absorption as set forth in any of the preceding claims, characterized in that the reflection of said substrate in the visible light range from 380 to 720 nm is less than 50% is due to colouration with soluble dyes or pigments.

The flat element having a dark surface and exhibiting a reduced solar absorption as set forth in any of the preceding claims, characterized in that said first pigments, which impart in the visible light range from 380 to 720 nm a reduced reflection of the coating less than 50% and in the spectral range of the near-infrared range from 720 to 1500 nm a transparency exceeding 50%, are selected from the group of organic pigments, selected from the group of azo pigments, selected from monoazo, disazo, β-naphtol, naphtol AS, lacquered azo, benzimidazolon, disazo condensation, metal complex, isoindolinon and isoindolin pigments, selected from the group of polycyclic pigments, selected from phthalocyanine, chinacridon, perylene and perinon, thioindigo, anthraquinone, anthrapyrimidin, flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylcarbonium, chino-phthalone, diketo-pyrrolo-pyrrole pigments.

The flat element having a dark surface and exhibiting a reduced solar absorption as set forth in any of the preceding claims, characterized in that said second pigments, which impart in the visible light range from 380 to 720 nm a reduced reflection of the coating less than 50% and in the near-infrared range from 720 to 1500 nm a reflection exceeding 40%, are selected from the group of inorganic pigments, selected from the group of metal oxides and hydroxides, from cadmium, bismuth, chromium, ultramarine pigments, selected from the group of coated, laminar mica pigments, selected more preferably from the group of rutile and spinelle mixed phase pigments.

The flat element having a dark surface and exhibiting a reduced solar absorption as set forth in any of the preceding claims, characterized in that said binder is selected

• a) from the group of solvent-based binders comprising acrylates, methacrylates, styrene-acrylates, styrene-methacrylates, selected from substituted polyolefins, selected from polystyrene and styrene copolmers, alkyd resins, selected from saturated and non-saturated polyesters or polyamides, polyimides, polyurethanes, polyethers, epoxy resins, silicones, chlorosulfonated polyethylene, fluorated polymers selected from fluorated acrylic copolymers or fluorosilicones;
• b) selected from the group of aqueous binders comprising the group of aqueous binders from alkyd resins, polyesters, polyacrylates, epoxides and epoxide esters, from the group of aqueous dispersions and emulsions, comprising dispersions and emulsions based on acrylate, methacrylate, styrene acrylate, polyethylene, polyethylene oxidate, ethylene acrylic acid copolymers, methacrylate, vinylpyrrolidone-vinylacetate copolymers, polyvinylpyrrolidone, polyisopropylacrylate, polyurethane, wax dispersions based on polyethylene, polypropylene, Teflon®, synthetic waxes, fluorated polymers, fluorinated acrylic copolymer in aqueous solution, fluorosilicones.

The flat element having a dark surface and exhibiting a reduced solar absorption as set forth in any of the preceding claims, characterized in that the particle size of said first pigments is smaller than 0.9 μm and the particle size of said second pigments is greater than or equal to 0.9 μm.

The flat element having a dark surface and exhibiting a reduced solar absorption as set forth in any of the preceding claims, characterized in that the reflection of said substrate in the spectral range 720 to 1500 nm exceeds 70%.

The flat element having a dark surface and exhibiting a reduced solar absorption as set forth in any of the preceding claims, characterized in that the reflection of said substrate and/or of said coating in the spectral range of visible light from 380 to 720 nm is less than 40%.

The flat element having a dark surface and exhibiting a reduced solar absorption as set forth in any of the preceding claims, characterized in that said first and/or second pigments in the spectral range of visible light from 380 to 720 nm result in a low reflection of the coating less than 40%.

The flat element having a dark surface and exhibiting a reduced solar absorption as set forth in any of the preceding claims, characterized in that the layer thicknesses of said substrate are in the range 10 μm to 8 mm, more particularly in the range from 20 μm to 6 mm.

The flat element having a dark surface and exhibiting a reduced solar absorption as set forth in any of the preceding claims, characterized in that the layer thicknesses of said coating are in the range 10 μm to 500 μm, more particularly in the range from 20 μm to 300 μm.

Use of flat element having a dark surface and exhibiting a reduced solar absorption comprising a dark substrate with a substantially evenly pigmented coating to reduce heating up of usually dark pigmented surfaces.