Preparation of green colorant from mixed rare earth and molybdenum compounds and process of surface coatings thereof

Patent metadata

Field	Value
Publication number	US-9242872-B2
Application number	US-201013260481-A
Country	US
Kind code	B2
Filing date	Mar 29, 2010
Priority date	Mar 27, 2009
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

The present invention proposes the development of inorganic green pigment, having a general formula, RE 2 MoO 6 (where RE is mixed rare earth metal and Mo is molybdenum metal) comprising mixed rare earth elements having atomic number in the range of 57 to 66 and having a composition of at least lanthanum in the range of 43-45% w/w, neodymium in the range of 33-35% w/w, praseodymium in the range of 9-10% w/w, samarium in the range of 4-5% w/w and other rare earths to a maximum of 5% w/w and molybdenum. The colorant can be prepared in a convenient and inexpensive method utilizing the solid state route by calcining the mixed rare earth carbonate and ammonium molybdate at a temperature range of 900-1100° C. for 3-6 h at a heating rate of 10° C./min followed by grinding. The well ground calcined powders were used for characterization of the pigments. The phase purity and optical properties of the prepared pigments were investigated. The pigment is useful as a colorant to various substrate materials such as plastics, paints, ceramics and the like.

First claim

I claim:

1. A process for the preparation of green inorganic colorant from mixed rare earth and molybdenum compounds, comprising the steps:
a) homogenizing a mixed rare earth carbonate and ammonium molybdate;
b) calcinating the homogenate obtained in step a) in air atmosphere; and
c) cooling and subsequent reduction of particle size,
wherein the mixed rare earth carbonate used in step a) is a mixture of rare earth elements having atomic number in the range of 57 to 66 and having a composition of at least lanthanum in the range of 43-45% w/w, neodymium in the range of 33-35% w/w, praseodymium in the range of 9-10% w/w, samarium in the range of 4-5% w/w and other rare earths to a maximum of 5% w/w.

2. The process as claimed in claim 1 , wherein calcination temperature in step b) is in the range of 900° C.-1100° C.

3. The process as claimed in claim 1 , wherein time for calcination in step b) is in the range of 3-6 h with a rate of heating of 10° C./min.

4. A green inorganic colorant, which comprises mixed oxides of rare earth elements and molybdenum, wherein said green inorganic colorant obtained, has a general formula RE 2 MoO 6 (where RE is mixed rare earth metal and Mo is molybdenum metal), wherein the colorant is obtained from a mixed rare earth carbonate which is a mixture of the rare earth elements having atomic number in the range of 57 to 66 and having a composition of at least lanthanum in the range of 43-45% w/w, neodymium in the range of 33-35% w/w, praseodymium in the range of 9-10% w/w, samarium in the range of 4-5% w/w and other rare earths to a maximum of 5% w/w.

5. The green inorganic colorant as claimed in claim 4 , wherein said colorant has chromaticity coordinates determined as per the CIE 1976 color scales at different temperatures are
900° C., L*=79.54, a*−−7.16, b*=20.90;
1000° C., L*=83.79, a*=−9.58, b*=29.97;
1100° C., L*=82.44, a*=−10.13, b*=36.44.

6. The green inorganic colorant as claimed in claim 4 , wherein the particle size of said colorant is in the range of 9-11 microns.

7. The green inorganic colorant as claimed in claim 4 , wherein said colorant comprises of a tetragonal crystal structure.

8. A process for colouring a substrate material, comprising the step of adding to said material a colouring amount of a green inorganic colorant as claimed in claim 4 , in an amount in the range of 5% by weight.

9. The process as claimed in claim 8 , wherein the material is selected from the group consisting of poly methacrylate, organic polymers, plastics, glasses, ceramics, paints, and textiles.

Assignees

• Reddy Mundlapudi Lakshmipathi
• Council Scient Ind Res

Inventors

• Reddy Mundlapudi Lakshmipathi

Classifications

• Y10T442/20

  Coated or impregnated woven, knit, or nonwoven fabric which is not [a] associated with another preformed layer or fiber layer or, [b] with respect to woven and knit, characterized, respectively, by a particular or differential weave or knit, wherein the coating or impregnation is neither a foamed material nor a free metal or alloy layer · CPC title

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title

• C01P2006/60

  Optical properties, e.g. expressed in CIELAB-values · CPC title

• C01P2006/88

  Isotope composition differing from the natural occurrence · CPC title