Phosphorescent marine products

Abstract

In one embodiment of the invention, a marine article of the invention includes a phosphorescent phosphor. A particularly advantageous phosphorescent phosphor comprises MAl2O4. As used herein, “M” is at least one cation selected from a group consisting of calcium, strontium, and barium. The phosphor comprises 0.001% to 10% of a europium activator, and 0.001% to 10% of at least one dopant selected from the group consisting of lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, tin and bismuth as a co-activator, in terms of mol % relative to the metal element expressed by M. The phosphorescent marine article has an afterglow corresponding to a luminance of at least 0.3 mCd / m2 for at least 420 minutes.

Description

[0001] This application is a continuation of application Ser. No. 11 / 316,797, filed Dec. 22, 2005, which is a continuation of application Ser. No. 10 / 791,363, filed Mar. 1, 2004, now abandoned, which is a continuation of application Ser. No. 09 / 778,973, filed Feb. 6, 2001, now abandoned, which is a continuation of application Ser. No. 09 / 152,377, filed Sep. 14, 1998, now U.S. Pat. No. 6,253,698, which are incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] During recent years, maritime activities both commercial and recreational have increased dramatically. As a consequence, visibility of marine articles is more important as U.S. bodies of water become crowded. The current means of increasing visibility of marine articles, such as, for example, buoy markers and boat indicators, include phosphorescent or fluorescent materials and brightly colored paints. However, these current means suffer from serious visibility and durability challenges. [0003] Generally, the afterg...

AI Technical Summary

Problems solved by technology

However, these current means suffer from serious visibility and durability challenges.

However, many of these sulfide phosphorescent phosphors are chemically unstable and show degraded light resistance, i.e., they suffer from problems that must be solved for practical use.

However, zinc sulfide phosphorescent phosphor is decomposed as the result of irradiation by ultraviolet radiation in the presence of moisture and thus, over time, blackens or reduces the phosphor's luminance.

Therefore, it is difficult to use this phosphorescent phosphor in fields where it is placed outdoors and exposed to a direct sunlight, that is, application is limited to luminous clocks / watches or clocks / watches and instrument dials, evacuation guiding signs or indoor night-time display.

The use of brightly-colored paints, including fluorescent paints, on marine floats do not solve the visibility problem in darkness.

Also, these paints become eroded or worn from the relatively soft and pliable surface of microporous resinous or foam marine floats, during use, so that any advantage which justifies the expense of applying such a paint is soon lost or severely diminished.

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