Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2000-03-10
2001-04-24
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031850, C106S472000, C106S473000, C106S476000, C106S478000, C106S499000, C106S505000
Reexamination Certificate
active
06221143
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to cationic pigments and aqueous compositions containing the same and, more particularly, to ink compositions useful for imaging applications, such as ink jet ink compositions.
2. Discussion of the Related Art
Aqueous systems are increasingly being used in many applications such as automotive and industrial coatings, paints, papers, inks, toners, adhesives, latexes, etc. as manufacturers face increased pressure to replace conventional solvent based systems. Such aqueous systems are known and generally contain a colorant, such as a dye, which is soluble in the aqueous vehicle, such as water or a mixture of water and a water-soluble or water-miscible organic solvent.
Although dye-based compositions are readily utilized, dyes have several disadvantages when used in aqueous ink systems. For example, dyes, being water-soluble in a water/organic mixture, may dissolve and run when exposed to moisture or water. Dye images may further smear or rub-off on contact with felt pen markers or upon being rubbed or touched by a finger. Dyes also exhibit poor light stability when exposed to visible or ultraviolet light.
Pigments are also known as colorants in aqueous compositions but have not received a wide degree of acceptance in aqueous systems, such as ink jet inks, because of problems associated with the performance and reliability of the composition, i.e., print properties, stability, latency, and the like. Examples of such pigments include carbon black, titanium dioxide white, cobalt blue (CoO—Al
2
O
3
), phthalocyanine blue, phthalocyanine green, and chrome yellow (PbCrO
4
).
U. S. Pat. Nos. 5,571,311; 5,630,868; 5,707,432; 5,803,959; and 5,837,045 and PCT Publication No. WO 96/18688; and PCT Publication No. WO 96/18695 (all incorporated in their entirety herein by reference), describe novel surface-modified pigments and aqueous compositions containing such surface-modified pigments. Although such surface-modified pigments are a considerable improvement over dye-based or traditional pigment systems (i.e. pigments requiring stabilization with a polymer or surfactant compositions), a continuing need exists for improved cationic based pigments, as well as aqueous or solvent based compositions containing such pigments, especially for use in ink compositions which require long term colloidal stability and lightfastness. It is also desirable to produce improved aqueous ink compositions which exhibit improved recoverability in their respective printing systems while providing good print properties. A further need exists for improved aqueous ink compositions which generate print images having improved waterfastness.
SUMMARY OF THE INVENTION
The present invention relates to cationic pigments having an organic group which comprises: a) at least one aromatic group, at least one C
1
-C
20
alkyl group, or both; and b) at least one cationically charged ionic group, at least one cationically chargeable ionizable group or both, and a corresponding counter-anion. In one embodiment of the present invention, the corresponding counter-anion is formed from hydroxy acids, such as a hydroxy carboxylic acid, a polyhydroxy carboxylic acid, a hydroxy sulfonic acid, a polyhydroxy sulfonic acid, a hydroxy sulfinic acid, a polyhydroxy sulfinic acid, a hydroxy hydrogen sulfate, a polyhydroxy hydrogen sulfate, and mixtures thereof. In a second embodiment of the present invention, the corresponding counter-anion is fluoride. In a third embodiment of the present invention, the corresponding counter-anion is mono-carboxy glycols, mono-sulfo glycols, mono-sulfinate glycols or mono-sulfate glycols, such as mono-carboxy or mono-sulfo ethylene glycol or polyethylene glycol; mono-carboxy or mono-sulfo propylene glycol; or polypropylene glycol, and mixtures thereof. In a fourth embodiment of the present invention, the corresponding counter-anion is a counter-anion formed from an aromatic carboxylic acid, aromatic sulfonic acid, aromatic sulfinic acid, aromatic hydrogen sulfate, or mixtures thereof.
Methods for producing the cationic pigments of the present invention described above are also disclosed. For example, a method of preparing a cationic pigment is disclosed including the steps of: preparing the cationic pigment dispersion having at least one organic group, the organic group comprises: a) at least one aromatic group, at least one C
1
-C
20
alkyl group, or both; and b) at least one cationically charged ionic group, at least one cationically chargeable ionizable group, or both, and a corresponding counter-anion; exchanging said corresponding counter-anion of said pigment dispersion with hydroxide; and adding one equivalent of an acid to said pigment dispersion to produce a cationic pigment with the desired corresponding counter-anion of said acid.
The present invention is further directed to ink compositions incorporating one or more of the cationic pigments described above.
The cationic pigments of the present invention may be used in aqueous or solvent based compositions containing conventional pigments. Such compositions include, for example, automotive and industrial coatings, paints, printing plates, papers, toners, inks (particularly, ink jet ink compositions), adhesives, latexes, textiles and fibers. The cationic pigments may be tailored to provide compatibility with the particular aqueous or solvent based system and provide easier, more complete dispersion, improved colloidal stability, improved smear resistance, improved waterfastness, good inter-color bleed qualities, and greater color intensity and shades, as well as decap stability and reliability of the printhead.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention relates to cationic pigments having attached at least one organic group which comprises: a) at least one aromatic group, at least one C
1
-
20
alkyl group, or both; and b) at least one cationically charged ionic group, at least one cationically chargeable ionizable group, or both, and a corresponding counter-anion.
In one embodiment of the present invention, the corresponding counter-anion is formed from hydroxy acids. The hydroxy acids can be polyhydroxy acids. Also, the hydroxy acids can be unsubstituted or substituted. Examples of such hydroxy acids include, but are not limited to, a hydroxy carboxylic acid, a polyhydroxy carboxylic acid, a hydroxy sulfonic acid, a polyhydroxy sulfonic acid, a hydroxy sulfinic acid, a polyhydroxy sulfinic acid, a hydroxy hydrogen sulfate, a polyhydroxy hydrogen sulfate, and mixtures thereof. Specific examples of such counter-anions include, but are not limited to, hydroxy alkyl carboxylates, polyhydroxy alkyl carboxylates, hydroxy alkyl sulfonates, polyhydroxy alkyl sulfonates, hydroxy alkyl sulfinates, polyhydroxy alkyl sulfinates, hydroxy alkyl sulfates, polyhydroxy alkyl sulfates, and mixtures thereof. Representative examples of such corresponding counter-anions include, but are not limited to, d-glucuronate, d-gluconate, isethionate, lactate, l-ascorbate, and mixtures thereof
In a second embodiment of the present invention, the corresponding counter-anion is fluoride (F
−
).
In a third embodiment of the present invention, the corresponding counter-anion is a mono-carboxy glycol, mono-sulfo glycol, mono-sulfinate glycol, or mono-sulfate glycol. The glycols can be polyglycols. Also, the glycols are mono-substituted.
Examples include, but are not limited to, mono-carboxy-, mono-sulfo-, mono-sulfinate-, or mono-sulfate- ethylene glycol; mono-carboxy-, mono-sulfo-, mono-sulfinate-, or mono-sulfate- polyethylene glycol; mono-carboxy, mono-sulfo, mono-sulfinate-, or mono-sulfate- propylene glycol; mono-carboxy-, mono-sulfo-, mono-sulfinate-, or mono-sulfate- polypropylene glycol; and mixtures thereof. The preferred counter-anion for this embodiment is represented by the formula:
RO—(CHR′CHR″—O)
y
—(CH
2
)
m
—X
where R is hydrogen, a substituted or unsubstitued alkyl group, or a substituted or unsubstituted aryl group (e.g., an aromatic group)
Cabot Corporation
Klemanski Helene
LandOfFree
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