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US 6,476,222 B2Granted
Preparation of heat stable pigment violet 23
AssigneeSun Chemical Corporation
InventorsNorman W. Smith, Terrence R. Chamberlain, Barbara N. Berg, George McLaren, Russell J. Schwartz
Life of this patent
Estimating the term…
Abstract
A process for improving the heat stability of Pigment Violet 23 by conditioning crude Pigment Violet 23 in the presence of about 1 to 10 wt. % of Pigment Violet 23 by-products (1), (2) and (3).
Claims12
A process for improving the heat stability of Pigment Violet 23 having the formula:
- comprising conditioning said pigment in the presence of about 1 to about 10 wt. %, relative to the weight of the crude pigment, of at least one compound selected from the group consisting of:
- wherein each R is independently selected from either H or CH3.
A process for forming Pigment Violet 23 of structural formula (I)
- having a specific surface area of from about 115 m2/g to about 125 m2/g, and heat stability, the process comprising conditioning a crude pigment of structural formula (I) in the presence of from about 1 to about 10 weight percent, based on the weight of the crude pigment, of at least one compound selected from the group consisting of:
- wherein each R is independently H or CH3.
- to form a heat-stabilized product pigment having the desired specific surface area.
Pigment Violet 23 of structural formula (I):
- having a specific surface area of from about 115 m2/g to about 125 m2/g, and heat stability.
Dependencies are inferred from the claim text.