Non-migrating metallized disazo green shade yellow pigment

Details Non-migrating metallized disazo green shade yellow pigment Non-migrating metallized disazo green shade yellow pigment

2003-09-18

2004-06-29

Powers, Fiona T. (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Azo

C534S582000, C534S602000, C534S700000, C534S748000, C534SDIG004, C106S031810, C106S496000, C430S108230, C524S190000

Reexamination Certificate

active

06756486

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to metallized disazo green shade yellow pigments which are excellent in at least one of color strength, brightness and heat stability, a process for their preparation, and use of the pigments in plastic, coating, and ink compositions.
BACKGROUND OF THE INVENTION
Azo yellow pigments are a class of colorants that are tinctorially strong and relatively inexpensive. Monoazo yellow pigments show good lighffastness and are particularly useful as coloring agents for paints and some printing inks. In plastics, however, monoazo yellow pigments tend to bloom and discolor at high temperatures. Monoazo yellow pigments also exhibit undesirable levels of bleed resistance.
Diarylide disazo yellow pigments, made from 3,3′-dichlorobenzidine, are much stronger tinctorially and show a much lower tendency to bloom and discolor at high temperatures. C.I. Pigment Yellow 17 is a strong green shade diarylide yellow and has often been used for plastics. W. Herbst and K. Hunger, Industrial Organic Pigments, VCH, New York, 1993, p. 252, state: “The plastics industry, however, uses P.Y. 17 extensively. P.Y. 17 is also frequently used in polyolefins. Its heat stability in these media was said to be about 220 to 240° C.” However, R. Az et al reported in Dyes and Pigments, 15, 1 (1991), that diarylide yellows are degraded to potentially carcinogenic by products (e.g., 3,3′-dichlorobenzidine) in plastics processed above 200° C., a temperature lower than that used in processing most plastics (e.g., 230-330° C.). To overcome these disadvantages, azo pigment manufacturers have actively pursued development of alternative types of azo yellows.
One alternative type of azo yellows are disazo yellow pigments made by coupling bis(acetoacetamido)benzenes into aniline derivatives. U.S. Pat. No. 5,616,778 describes coupling 1,4-BAAAB into 2,5-dicarbomethoxyaniline (to give C.I. Pigment Yellow 155) and heating the pigment in an organic solvent at 80-150° C. for up to 6 hours. U.S. Pat. No. 5,559,216 relates to the preparation of printing inks involving the step of preparing disazo pigments in the presence of nonionic surfactants having a 5-90° C. cloud point to give pigments suitable for printing inks. This patent does not mention any metallized pigments. German Offenlegungsschrift 3501199 describes coupling 1,4-BAAAB into mixtures of anilines substituted with one or two carboalkoxy groups to give pigments that disperse easily into polypropylene. Canadian Patent 1135688 describes the pigments resulting from coupling 1,4-BAAAB into anilines substituted with nitro and carboalkoxy groups. Czech Patents 188727 and 185798 describe the pigments resulting from coupling 1,4-BAAAB into anilines substituted with urea groups. U.S. Pat. Nos. 4,146,558 and 4,103,092 describe coupling 1,4-BAAAB into anilines substituted with quaternized aminoalkyl or aminoalkoxy groups to give water-soluble dyes. Swiss Patent 585,247 describes coupling 1,4-BAAAB into an aminoquinoline derivative and heating with N,N-dimethylformamide at 140 C to obtain a greenish yellow pigment for coloring polyvinyl chloride plastics. U.S. Pat. No. 3,978,038 provides pigments resulting from coupling 1,4-BAAAB or various substituted 1,4-BAMBs into anilines substituted with nitro groups. U.K. Patents 1400533 and 1396526 describe the pigments resulting from coupling 1,4-BAAAB or various substituted 1,4-BAAABs into anilines substituted with a chlorine and methyl groups or two chlorine groups. German Offenlegungsschrift 2336915 describes the pigments resulting from coupling 1,4-BAAAB or various substituted 1,4-BAAABs into anilines substituted with nitro groups and other groups. U.S. Pat. No. 5,889,162 describes the pigments resulting from coupling 1,4-BAAAB or various substituted 1,4-BAAABs into o-phenetidine.
Another alternative type of azo yellows are the metallized monoazo yellows. C.I. Pigment Yellow 62 is a slightly redder yellow, but much weaker tinctorially than C.I. Pigment Yellow 17. A recent metallized monoazo yellow, disclosed in U.S. Pat. No. 5,669,967, is stronger tinctorially than C.I. Pigment Yellow 17, but is an even redder yellow (though not as red as metallized medium shade yellows C.I. Pigment Yellows 183 and 191). A metallized disazo yellow described in U.S. Pat. No. 6,254,671 is a green shade yellow, but much weaker than C.I. Pigment Yellow 17.
Two alternative yellow pigments are C.I. Pigment Yellow 109 (isoindolinone) and C.I. Pigment Yellow 138 (quinophthalone). These green shade yellows are very close in hue to C.I. Pigment Yellow 17, but are much more expensive, much weaker, and contain eight chlorine atoms per molecule, a potential environmental disadvantage.
Plastics processors that use diarylide yellows are particularly conscious of the increased costs of using the higher concentrations of weaker yellows required for coloring plastics to the required tinctorial strengths. Although one disazo pigment made from coupling 1,4-BAAAB, C.I. Pigment Yellow 155, is a commercial pigment, this pigment (Sandorin 4G) is much weaker and slightly redder than C.I. Pigment Yellow 17 and shows poor heat stability (see below) at 288 C, a temperature commonly used to process polypropylene and other plastics. Thus, there is a need for a new green shade yellow azo pigment that shows strength comparable to C.I. Pigment Yellow 17, as well as good heat stability and good lightfastness.
Pigments that are used in plastics for food and beverage packaging must resist extraction in order to avoid contaminating the packed consumable. Organic substances, such as ethyl alcohol, are common ingredients in food and beverages that could cause pigment extraction. Plastic processors have a limited choice in using Pigment Yellow 138 or Pigment yellow 180 for food and beverage packaging in the green-shade yellow color range. Thus, there is a need for economical green-shade yellow azo pigments that exhibit good color strength, heat stability and resistance to extraction/bleed resistance.
SUMMARY OF THE INVENTION
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Rather, the sole purpose of this summary is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented hereinafter. The present invention generally relates to disazo yellow pigments suitable for use as coloring agents, processes for their preparation and their use in plastic, coating and ink compositions. The disazo yellow pigments exhibit both a desirable green shade and strength.
One aspect of the invention relates to laked disazo pigment compounds represented by Formula I:
wherein R
1
and R
2
are independently selected from hydrogen, hydroxy, halogen, an alkyl group having 1 to about 4 carbon atoms, an alkoxy group having 1 to about 4 carbon atoms, a halo-alkyl group containing 1 to about 4 carbon atoms, an alkoxy carbonyl group having 1 to about 5 carbon atoms; R
3
and R
4
are independently selected from hydrogen, hydroxy, halogen, an alkyl group containing from 1 to about 4 carbon atoms, an alkoxy group containing from 1 to about 4 carbon atoms, and halo-alkyl groups containing from 1 to about 4 carbon atoms; and M is at least one divalent metal.
Another aspect of the invention relates to a method of making a green shade yellow pigment involving coupling a diazonium component containing a compound prepared from an aromatic amine represented by Formula II
wherein R
3
and R
4
are as described above with a coupling component comprising a coupler represented by Formula III
wherein R
1
and R
2
are as described above; and metallizing with a salt.
To the accomplishment of the foregoing and related ends, certain illustrative aspects of the invention are described herein in connection with the following description. The

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