Xuan Bao Hao Corp

Product Name	UV Vis Range
Introduction
H.W. Sands Corp. is the exclusive World-wide Distributor to the Imaging Industry for the Photochromic Dye manufacturing Unit of PPG Industries, Pittsburgh, PA. PPG's Photosol^TM photochromic dyes reversibly alter their color upon exposure to ultraviolet sources. Full color changes appear with exposure to UV light from milliseconds using a flash gun, to 20 to 60 seconds in the sunlight. When sunlight or ultraviolet (UV) radiation is applied, the dye becomes excited and the molecular structure is changed allowing a color to appear. When the stimulus (sunlight/UV) is removed, the dye will return to a state of rest, which is its colorless form. The photochromics can be activated by UV light ranging from 300 to 360 nanometers. PPG's Photosol^TM photochromic dyes are supplied as a crystalline organic dye. The proprietary organic materials come in four base colors: blue, yellow, purple and orange/red. When combined, additional colors such as green, brown and gray can be produced. By further adjusting the rations of combinations of these four photochromic dyes, various additional shades of greens, blues, browns and reds can be achieved. By using a base UV transparent color, additional photochromic color effects can be produced, i.e., base pink plus blue photochromic used in sunlight will give a purple color. Photochromics can be used in various imaging applications including inks and are soluble in most organic solvents.
Applications
Photosol^TM photochromic dyes can be used to develop products that are suitable for printing, or other imaging applications. Existing products include textiles that evolve new patterns upon exposure to sunlight, security devices that are observable spectroscopically or by specialized instruments, inks for screen printing and laminates, automotive, industrial and aerospace coatings. Photosol^TM photochromic dye can be subjected to processing temperatures of 180^oC to 240^oC (350^oF-460^oF) without degradation. Thermal degradation is a function of the combination of time and temperature. The shorter the time and the lower the temperature, the better the performance.
Technical Overview
Photochromics are a colorless isomer that contains a spirocarbon atom. This carbon atom is SP3 hybridized and serves to separate the molecule into two halves. Because of the highly localized pi systems that are separated by a SP3 hybridized carbon, all absorption is in the UV part of the spectrum with none in the visible and hence the molecule appears colorless. When the molecule absorbs UV light, the spiro atom opens. The molecular structure then changes to one of extended conjugation and the molecule now absorbs light in the visible region. The life of a photochromic depends on the amount of photochromic dye used, the stabilizers used, and the material in which it is used. Generally, it is suggested that 0.1 gram per square foot be used to provide an adequate reservoir of photochromics. The use of ultra-violet absorber will also extend the life of the photochromic, but will reduce the color intensity.
Dyes
MSA5003	430nm
MSA5830	486nm
MSA7049	505nm
MSA7106	535nm
MSA2650	615nm
MSA3367	616nm