Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-11-22
2002-06-25
Sanders, Kriellion (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C106S410000, C106S411000, C106S412000, C106S413000, C106S493000, C106S494000, C106S495000, C106S496000, C106S497000, C106S498000
Reexamination Certificate
active
06410619
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to processes of preparing conditioned organic pigments with one or more acrylic polymer dispersants.
Crude organic pigments are obtained after chemical synthesis and are generally unsuitable for use as pigments in coating formulations. Consequently, crude organic pigments undergo one or more finishing steps that modify particle size, particle shape, surface characteristics, and/or crystal structure of the pigment in such a way that provides a pigment of good pigmentary quality. See, for example, W. Carr, “Improving the Physical Properties of Pigments” in
Pigment Handbook
, Vol. III (New York: John Wiley & Sons, Inc., 1973), pages 29-35; W. Herbst and K. Hunger,
Industrial Organic Pigments
(New York: VCH Publishers, Inc., 1993), pages 205-207; R. B. McKay, “The Development of Organic Pigments with Particular Reference to Physical Form and Consequent Behavior in Use” in
Rev. Prog. Coloration,
10, 25-32 (1979); and R. B. McKay, “Control of the application performance of classical organic pigments” in
JOCCA,
89-93 (1989) herein incorporated by reference. In some finishing processes, one or more of the finishing steps can include a strong mineral acid or caustic alkali, followed by precipitation of the pigment, and/or milling the crude pigment. A pigment conditioning process that avoids a strong acid or caustic step would be desirable because elimination of such a step would significantly reduce environmental and health risks associated with caustic chemicals and lower costs associated with pigment conditioning processes. Crude organic pigments having undergone a pigment conditioning process are called conditioned organic pigments and are typically sold commercially.
Milling methods are known to improve various properties of organic pigments. E.g., U.S. Pat. Nos. 5,614,014, 5,626,662, and 5,704,556. However, milling in the presence of acrylic polymers as specified in the present invention has not previously been described.
Acrylic copolymers have been used to disperse and maintain, in a dispersed state, conditioned organic pigments in coatings and other materials. See U.S. Pat. Nos. 5,859,113 and 5,219,945, as well as U.S. Pat. Nos. 4,293,475, 4,597,794, 4,734,137, 5,530,043, and 5,629,367, herein incorporated by reference. These dispersions are combined with other components (such as resins and other additives) to form paints and other coatings and other materials. Although dispersing agents have been used to disperse conditioned organic pigments in liquid dispersions, very little is known about the use of copolymer dispersants during processes of conditioning crude organic pigments prior to their isolation as dry powders. U.S. Pat. No. 3,806,464 discloses a method for encapsulating pigments with acrylic polymers and U.S. Pat. No. 4,734,137 discloses a method for reprecipitating pigments that have been dissolved in solvents containing caustic alkali and acrylic resins. Neither patent, however, discloses a milling process, a critical feature of the present invention that provides readily dispersible pigments under relatively gentle conditions.
SUMMARY OF THE INVENTION
The present invention relates to a process for making conditioned organic pigments using at least one acrylic copolymer dispersant. In certain embodiments, these processes may avoid the need for the normal processes requiring the use of strong acids having a pH of less than 2. The conditioned organic pigments formed from the processes of the present invention may be used, in part, in pigmented formulations such as coating compositions, paints and printing inks. The process comprises
(a) milling a mixture comprising:
(1) one or more crude organic pigments;
(2) at least about 0.1 % by weight, relative to the organic pigment, of one or more acrylic copolymer dispersants (preferably containing at least one polymerized monomer having an aromatic functionality in an adsorbing segment); and
(3) 0 to about 100 parts by weight, relative to the organic pigment, of a milling liquid in which the organic pigment is substantially insoluble; and
(b) isolating the milled organic pigment.
The milling mixture may also include one or more of the following:
(4) one or more milling additives; and/or
(5) one or more surface treatment additives.
Upon completion of the milling, one or more of the following may be added to flocculate the milled pigment prior to isolation:
(6) one or more acids;
(7) one or more divalent metal salts; and/or
(8) one or more quaternary ammonium salts.
All pigments produced from the processes of the present invention are highly dispersible and provide enhanced color in wet and/or dried coating systems.
The term “crude organic pigment” as used herein refers to an organic pigment that has not been treated using the process of the present invention. Such crude organic pigments may or may not be modified after chemical synthesis and may or may not have desirable coloristic properties in coatings systems.
The term “conditioned organic pigment” as used herein refers to an organic pigment that is modified by the process of the present invention after chemical synthesis.
DETAILED DESCRIPTION OF THE INVENTION
Processes of the present invention require milling a crude organic pigment or reprocessing of a finished organic pigment with one or more acrylic polymer dispersants, an optional milling liquid, and optionally one or more milling additives, followed by isolation. The components of the milling mixture may be added or combined in any order such that preferably (but not necessarily) all are present at the start of the milling. Suitable milling methods include dry-milling methods, such as jet milling, ball milling, and the like, and wet-milling methods, such as salt kneading, sand milling, bead milling, and the like in a milling liquid. The resultant organic pigments contain readily dispersible individual particles or loosely bound aggregates.
Crude Organic Pigments
Crude organic pigments used in the practice of the present invention include perylenes, quinacridones, phthalocyanines, isoindolines, dioxazines (that is, triphenedioxazines), 1,4-diketopyrrolopyrroles, anthrapyrimidines, anthanthrones, flavanthrones, indanthrones, perinones, pyranthrones, thioindigos, 4,4′-diamino-1,1′-dianthraquinonyl, and azo compounds, as well as substituted derivatives thereof. Preferred organic pigments are aromatic pigments such as perylene, quinacridone, phthalocyanine, isoindoline, and dioxazine pigments. Mixtures, including solid solutions, may also be prepared.
Perylene pigments used in the practice of the present invention may be unsubstituted or substituted. Substituted perylenes may be substituted at imide nitrogen atoms for example, and substituents may include an alkyl group of 1 to 10 carbon atoms, an alkoxy group of 1 to 10 carbon atoms and a halogen (such as chlorine) or combinations thereof. Substituted perylenes may contain more than one of any one substituent. The diimides and dianhydrides of perylene-3,4,9,10-tetracarboxylic acid are preferred. Crude perylenes can be prepared by methods known in the art. Please review, W. Herbst and K. Hunger,
Industrial Organic Pigments
(New York: VCH Publishers, Inc., 1993), pages 9 and 467-475, H. Zollinger,
Color Chemistry
(VCH Verlagsgessellschaft, 1991), pages 227-228 and 297-298, and M. A. Perkins, “Pyridines and Pyridones” in
The Chemistry of Synthetic Dyes and Pigments
, ed. H. A. Lubs (Malabar, Fla.: Robert E. Krieger Publishing Company, 1955), pages 481-482, incorporated herein by reference.
Phthalocyanine pigments, especially metal phthalocyanines may be used in the practice of the present invention. Although copper phthalocyanines are preferred, other metal-containing phthalocyanine pigments, such as those based on zinc, cobalt, iron, nickel, and other such metals, may also be used. Metal-free phthalocyanines are also suitable but are generally less preferred. Phthalocyanine pigments may be unsubstituted or partially substituted, for example, with one or more alkyl (having 1 to 10 carbon atoms
Greene Michael J.
King James G.
McIntyre Patrick F.
Schulz Gregory R.
Visscher Karyn B.
Bayer Corporation
Gil Joseph C.
Roy Thomas W.
Sanders Kriellion
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