Reflector with resistant surface

Abstract

Reflectors, for example, for lamps used for technical lighting purposes, having a surface which is resistant to mechanical and chemical attack and has high total reflectivity. The body (10) of the reflector, which is, for example, a rolled aluminum product such as a foil, a strip of a sheet, has a surface layer in the form of a layer system containing (a) a pretreatment layer (11), onto which is deposited (b) a functional layer (12) with silanes, having organo-functional groups, of a metal compound, and onto which is deposited (c) a metal-containing reflective layer (13). Layer (a) is deposited on the reflector body and increases the strength of bonding to the above lying layers (a) and (b). Layer (b) effects a flattening and increase in the mechanical strength of the above lying layer (c). The pretreatment layer can be a layer produced by anodic oxidation. The functional layer (b) can be a sol-gel layer. The reflective layer (c) can be a metallic reflective layer, in some cases with one or more protective layers, which are deposited, e.g., by vacuum thin layer deposition process.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a reflector having, on a reflector body, a surface which is resistant to mechanical and chemical attack and exhibits high total reflectivity. The invention relates also to a process for its manufacture and the use of such reflectors with a resistant surface layer.[0003]2. Background Art[0004]Known is the production of bright finish strips e.g. of high purity aluminium or AlMg alloys based on aluminium having a purity of 99.8% and higher, such as e.g. 99.9%, and roll surfaces that produce diffuse or directionally reflected light depending on the application. To increase the directional reflectivity (degree of brightness) of such strips, it is also known to brighten the strips chemically or electrolytically, then to create a e.g. 1.5 μm thick protective layer by anodic oxidation.[0005]Anodising processes are chemical treatments which suffer the disadvantage of requiring considerable precau...

AI Technical Summary

Benefits of technology

[0013]c) a metallic reflective layer,where layer a) is deposited on the reflector body and increases the strength of bonding to the layers lying above it, and layer b) effects a flattening and an increase in the mechanical strength of the above lying layer c).DETAILED DESCRIPTION OF THE INVENTION

[0031]The electrolytic production of such layers a) allows the thickness of the layer to be regulated very precisely. The maximum thickness of aluminium oxide barrier layer achieved is in nanometers (nm) approximately the value of the applied voltage (V), i.e. the maximum thickness of layer is linearly dependent on the anodising voltage—whereby the voltage drop at the outer layer has to be taken into consideration. The exact value of the maximum layer thickness achieved as a function of the applied direct voltage U and—taking into account the voltage drop at the outer layer—can be determined by a simple trial and lies in the region of 1.2 to 1.6 nm / V. The exact value of layer thickness is a function of the applied voltage, the electrolyte used i.e. its composition and its temperature.

Problems solved by technology

Anodising processes are chemical treatments which suffer the disadvantage of requiring considerable precaution in order to avoid contamination of the environment The extent of these precautions increases with increasing thickness of the oxide layer.

The known processes have the further disadvantage that high purity, expensive bright-finish alloys based on aluminium of very high purity have to be employed.

This represents a loss in energy.

Such a layer system, however, suffers the disadvantage that the surfaces are very sensitive to physical attack, such as mechanical or chemical attack e.g. by corrosive media.

This is also a possible way of arriving at reflective aluminium materials without having to employ anodising; the layered structure described in EP-A-0 568 943 is, however, not resistant to mechanical effects and corrosion to the extent desired.

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