Infrared reflective color pigment

Abstract

The present invention provides new solid solutions having a corundum-hematite crystalline structure which are useful as inorganic color pigments. Solid solutions according to the present invention include a host component having a corundum-hematite crystalline structure which contains as guest components one or more elements from the group consisting of aluminum, antimony, bismuth, boron, chrome, cobalt, gallium, indium, iron, lanthanum, lithium, magnesium, manganese, molybdenum, neodymium, nickel, niobium, silicon, tin, titanium, vanadium, and zinc. Solid solutions according to the present invention are formed by thoroughly mixing compounds, usually metal oxides or precursors thereof, which contain the host and guest components and then calcining the compounds to form the solid solutions having the corundum-hematite crystalline structure. Some of the new solid solutions according to the present invention exhibit relatively low Y CIE tri-stimulus values and relatively high near infrared reflectance.

Description

REFERENCE TO PRIOR APPLICATION[0001] This is a continuation-in-part of application Ser. No. 09 / 178,957, filed Oct. 26, 1998.[0002] The present invention concerns new solid solutions which are useful as inorganic color pigments. More particularly, the present invention concerns new solid solutions having a corundum-hematite crystalline structure which are useful as inorganic color pigments, some of which exhibit low Y CIE tri-stimulus values and high reflectivity in the near infrared portion of the electromagnetic spectrum.[0003] Chromium green-black hematite (basic chemical formula: Cr.sub.2O.sub.3) is an inorganic color pigment, C.I. Pigment Green 17, having a corundum-hematite crystalline structure. It is commonly used to impart a green color to ceramics, paints, polymers, and other materials. The DCMA Classification and Chemical Description of the Complex Inorganic Color Pigments, Third Addition (1991), published by the Dry Color Manufacturer's Association, states that its compos...

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Benefits of technology

0009] Some of the new solid solutions according to the present invention, such as for example chrome oxide as a host component containing the elements iron, boron, and titanium as guest components, exhibit dark drab colors in the visible and high reflectivity in the near infrared portions of the electromagnetic spectrum. One of the primary uses for new solid solutions having these properties would be as inorganic color pigments in military camouflage paint or netting applications, which would permit the radiati

Problems solved by technology

A chromium green-black hematite pigment manufactured by Bayer Corporation of Germany, product number AC 5303, was observed to exhibit a higher near infrared reflectance than other chromium

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