Super-LumiNova
LumiNova is a trademark of the Japanese manufacturer Nemoto & Co. Ltd.. , Are offered under the inorganic Afterglow. The pigments are based on alkaline earth aluminates and were developed and patented by Nemoto. Under the name Superluminova a development with increased luminosity is offered specifically for the watch industry. LumiNova pigments are available in fluorescent yellow-green, blue-green and blue-violet.
The pigments were developed as an alternative to the previously used on radium or tritium based self-luminous substances later in 1998. In contrast to prior products, these pigments exhibit no radioactivity and are consequently virtually no degradation.
Composition
The pigments according to the manufacturer based on strontium aluminate ( SrAl2O4 ). The crystal lattice is doped with europium, which serves as an activator for the visual effect. Other rare metals are used as co- activators.
Operation
The pigments shine through inorganic phosphorescence. By excitation with artificial or natural light, electrons are lifted into the excitation centers to a higher energy level. This excitation centers consist of atoms that are incorporated into the crystals of Luminova. The more intense and longer the exposure is made, the more complete the excitation up to saturation and then the brighter the glow. With a certain probability / time the electrons fall back to the ground state, indicating energy in the form of visible light.
This decay takes (essentially) a characteristic typical of the material time. By suitable material mixture may be a long burn time combined with very high at the beginning, but this quickly decaying brightness. So the then very bright luminous hands directly after turning off the light or leaving a bright space, that is, if the sense of sight is not yet adjusted to the darkness, be easy to read, but even after a prolonged dark phase, at about the end of the night.
Properties
Coloristic
Two different color is required to identify the color of the luminescent pigments clear: the color under sunlight and fluorescent inks. Fluorescent colors are, for example, green, yellow or red In addition, there are various gradations of light color from light to dark. Standard colors are listed in ISO 3157 and ISO / DIS 17514.
Stability
Due to the fact that after one charge-discharge cycle has been no chemical alteration of the pigments retain their afterglow theoretically unlimited period. A reduction of the light intensity will be very slow, almost imperceptible, instead. This reduction increases with the degree of coloring of the pigments. Intensive gefärbe types ( eg bright green) lose so quickly in intensity as neutral. High temperatures up to several hundred degrees Celsius without problems. To be avoided is merely a prolonged contact with water or high humidity, since this forms a hydroxide layer, which affects the luminous intensity negative.
Toxicity
In contrast to the tritium also used in bright color strontium containing no radioactive substances. Since the pigments consist of a alkaline earth metal aluminate -based shows an alkaline behavior in contact with water. Otherwise, the handling in accordance with the common safety and health rules shall be classified as harmless.
Applications
As with all Nachleuchtpigmenten the best-known application is the luminescent coating on watch dials. Here the pigments used to illuminate dial and hands in the dark. It is used on signs and boards for marking of escape routes for emergencies.