Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2000-10-27
2003-01-14
Green, Anthony J. (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S412000, C106S413000, C106S472000, C106S476000, C106S494000, C106S495000, C106S496000, C106S497000, C106S498000
Reexamination Certificate
active
06506245
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to colored pigments and aqueous and non-aqueous compositions containing the same. The present invention further relates to methods of preparing colored pigments and their use in a variety of applications, including inks, such as ink jet inks and the like.
The use of colored pigments in the industry has gained wide acceptance in a number of applications. Generally, the particle size of available colored pigments has hindered efforts to improve products containing colored pigments. Currently, the only satisfactory way to make colored pigments having small particle sizes has been with the use of a dispersant, such as surfactants and polymeric resins. However, while the colored pigments having the small particle sizes can be made, these colored particles are only stable with the aid of the dispersant, and if the dispersant is substantially removed, the colored pigments will agglomerate and thus lose their small particle size. The need for the dispersant to be always present has, however, prevented or hindered the use of colored pigments in many applications, since the presence of the dispersant must be taken into account when formulating compositions, such as inks. Other problems associated with the use of dispersant include: dispersants can be incompatible with other ink components, the dispersants must be used in large quantities, and the inks with surfactants generally has low surface tension.
Also, 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. No. 5,837,045, to Johnson et al. describes novel surface-modified colored pigments and aqueous compositions containing such surface-modified colored pigments. Although such surface-modified colored pigments are a considerable improvement over dye-based or traditional pigment systems (i.e. pigments requiring stabilization with polymer or surfactant compositions), a continuing need exists for improved surface-modified colored pigments and processes for making the same, as well as aqueous or solvent based compositions containing such surface-modified colored 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 latency and recoverability in their respective printing systems while providing good print properties. A further need exists for improved colored pigments and ink compositions which contain the colored pigments.
SUMMARY OF THE INVENTION
The present invention relates to colored pigments having one or more desired parameters and/or properties without the addition of dispersants. These parameters and/or properties include:
a particle size distribution of from about 10 nm to about 300 nm;
an accusizer number of less than 10
10
particle/ml of dispersion (at 15% solids) which are greater than 0.5 micron;
a filterability such that when in a liquid medium, 100 ml with 10% solids of the colored pigment filters through a 3 micron nylon absolute filter;
a colored pigment purity of greater than about 80%, based on extractable material; and/or
a stability such that the above-described properties do not change by more than 50% at 25 degrees C for 1 week.
The above-described colored pigment is preferably in an aqueous or non-aqueous media having no external dispersant present.
The present invention further relates to a colored pigment having attached at least one organic group and having one or more of the above-described characteristics.
In addition, the present invention relates to a process for preparing surface-modified colored pigments. The process involves combining at least one treating agent and at least one type of colored pigment in a container to form a mixture and subjecting the mixture to high shearing and introducing at least one diazotizing agent to the mixture at least for a portion of time while the high shearing is taking place, and preferably while the entire high shearing is taking place, such that a reaction product is formed and contains surface-modified colored pigment(s). The treating agent has an organic group which comprises at least one diazotizable group. In a preferred embodiment, the diazotizable group comprises a) at least one aromatic group, at least one C
1
-C
20
alkyl group, or mixtures thereof, and b) at least one ionic group, ionizable group, nonionic group, or mixtures thereof. Preferably, in this process, the product yield results in from about 30% to about 100% of the colored pigment having a particle size of from about 10 nm to about 300 nm.
The present invention is further directed to a process for preparing ink compositions incorporating the colored pigments described above.
The colored pigments prepared by the process 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, papers, toners, inks (particularly, ink jet ink compositions), adhesives, latexes, textiles and fibers. The colored pigments may be tailored to provide compatibility with the particular aqueous or solvent based system and provide easier, more complete dispersion, improved colloidal stability and greater color intensity and shades.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention relates to colored pigments having one or more desired characteristics and methods of making these colored pigments, as well as their use in a variety of applications. The colored pigments of the present invention can be characterized such that the colored pigments have at least one of the following characteristics wherein an aqueous or non-aqueous media:
a) a particle size distribution of from about 10 nm to about 300 nm;
b) an accusizer number of less than 10
10
particle/ml of dispersion (at 15% solids) which are greater than 0.5 micron;
c) a filterability such that when in a liquid medium, 100 ml with 10% solids of the colored pigment filters through a 3 micron nylon absolute filter;
d) a colored pigment purity of greater than about 80%, based on extractable material; and/or
e) a stability such that the above-described properties do not change by more than 50% at 25 degrees C.
The above-described colored pigment preferably has one or more of the above characteristics when present in an aqueous or non-aqueous media having no added external dispersant present.
The pigment can be, but is not limited to, pigments traditionally used in ink compositions (including inkjet ink compositions), coating compositions (including paint formulations), liquid and solid toners, films, plastics, rubbers, and the like. Examples include, but are not limited to, black pigments (e.g., carbon products
Kinney Thomas A.
von Gottberg Friedrich K.
Welch John F.
Yu Yuan
Cabot Corporation
Green Anthony J.
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