Study On The Preparation Of Environmental Protection Type Of Optically Variable Nano Thin Film Materials

Optical variable material is a senior first-line anti-counterfeiting materialsrecognized internationally. It has been widely used in currency, securities, cigarette, wineand other security. In the production process, which has tended to be mature, from thedesign, the production process of a series, to the final product, optical variable materialsare inevitably containing heavy metals. How to avoid the heavy metal, and not lose somepaste characteristics of chromotropic material itself, such as brightness, chroma, flop, is atechnical problem today.This paper studies a titanium base, aluminum base composite material withoutheavy metal environmental protection type optical variable materials. This study from the5layers symmetrical structure,we have studied environmental protectiontype opticallyvariable materials or4kinds of material sturcture:(1). Titajium absorbing layer/MgF2dielectric layer/Titanium reflector layer/MgF2dielectric layer/Titanium Absorbing layer;（2）.Titajium absorbing layer/SiO2dielectric layer/Titanium reflector layer/SiO2dielectric layer/Titanium Absorbing layer;（3）.Titajium absorbing layer/SiO2dielectric layer/Aluminum reflector layer/SiO2dielectric layer/Titanium Absorbing layer;（4）.The SiO2protective layer/Titanium absorbing layer/SiO2dielectric layer/Titanium absorbing layer/SiO2dielectric layer/Titanium absorbing layer/SiO2protective layer.The results show that: with the above5kinds of structure design to obtain the sampleoptical variable materials, the structural design of1, the complexity of the technology ofpreparing MgF2, not conducive to the formation of good flop products; structural designof2, can get the product angle dependent color effect ideal, but its brightness andcorrosion resistance could be improved the structure design;3, can greatly improve thebrightness and brightness of the sample, but the corrosion type slightly worse; structuredesign4, seen from the results, the flop, product brightness and have more ideal. At thesame time, the detection of heavy metal material structure, basically reached theexpected.The samples prepared in this study after testing, the following verification:(1) the MgF2as dielectric layer material, titanium absorbing layer, the reflectionlayer structure design, the ideal titanium absorption layer thickness of9nm, titaniumreflecting layer thickness of70nm, at the same time, magnesium fluoride used as adielectric layer, higher requirements on equipment, to increase the ion assisted, baking equipment, or material membranes were surface is not smooth, more defects, greatlyaffect the performance of the product.(2) using silica instead of magnesium fluoride, preparation of environmentalprotection type photochromic materials better, the membrane surface is smooth, can getthe good flip-flop effect.(3) made from aluminum reflector, replace titanium reflecting layer, can greatlyimprove the brightness of environment-friendly photochromic materials and brightness.But the design and preparation of samples, after a period of time, the color will drift,brightness, brightness will gradually becomes poor, analysis may be, titanium at roomtemperature surface will naturally formed oxide layer is a layer of titanium, such astitanium dioxide, titanium oxide, three two five three titanium oxide, the chemicalproperties titanium is very stable, when titanium absorbing layer, the thickness of thin,and in the nanocrystalline state, nature is lively, the formation of titanium oxide easily,change the optical properties of titanium absorbing layer, resulting in over time, colordrift, brightness and angle dependent color effect weakening.(4) in the titanium absorption increase silica layer about5nm layer, does not changethe brightness, environmental protection type photochromic material brightness andangle dependent optical properties, also greatly increased the resistanceenvironment-friendly photochromic materials, so that it can be preserved for a long time.(5) the preparation of heavy metal environmental protection type photochromicmaterials without lead, arsenic, mercury, cadmium, chromium and nickel in quantity,content were36mg/kg,9.8mg/kg, may be coated material not purity, containing a smallamount of chromium, nickel incidental.