Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2000-06-12
2002-05-21
Rodee, Christopher (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S114000, C430S108240, C430S137100, C106S411000
Reexamination Certificate
active
06391507
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the use of a certain copper phthalocyanine composition in electrophotographic toners and developers, powder coating materials and inkjet inks.
In electrophotographic recording techniques a “latent charge image” is produced on a photoconductor. This latent charge image is developed by applying an electrostatically charged toner which is then transferred, for example, to paper, textiles, foils or plastic and is fixed by means, for example, of pressure, radiation, heat, or the action of a solvent. Typical toners are one- or two-component powder toners (also called one- or two-component developers); furthermore, special toners are employed, examples being magnetic or liquid toners, latex toners, polymerization toners and microencapsulated toners based on wax, for example.
One measure of the quality of a toner is its specific charge q/m (charge per unit mass). In addition to the sign and level of the electrostatic charge, the rapid attainment of the desired charge level and the constancy of this charge over a prolonged activation period, in particular, is a decisive quality criterion. Moreover, the insensitivity of the toner to climatic effects such as temperature and atmospheric humidity is another important criterion for its suitability.
Both positively and negatively chargeable toners are used in photocopiers, laser printers, LED (light emitting diode), LCS (liquid crystal shutter) printers or other digital printers based on electrophotography, depending on the type of process and type of equipment.
In order to obtain electrophotographic toners or developers with either a positive or a negative charge it is common to add charge control agents. As the color-imparting component in color toners, use is typically made of organic color pigments. As compared with dyes, color pigments have considerable advantages on account of their insolubility in the application medium, such as improved thermal stability and lightfastness, for example. On the basis of the principle of subtractive color mixing it is possible, with the aid of the three primary colors yellow, cyan and magenta, to reproduce the entire spectrum of colors visible to the human eye. Exact color reproduction is only possible if the particular primary color satisfies the precisely defined color requirements. If this is not the case, some shades cannot be reproduced and the color contrast is inadequate.
In the case of full color toners, the three toners yellow, cyan and magenta must not only meet the precisely defined color requirements but must also be matched exactly to one another in their triboelectric properties, since they are transferred one after another in the same device.
6- and 7-color systems are likewise known. The base colors are red, green, blue, cyan, magenta, yellow and black. It is also possible to produce full color prints by the Pantone Hexachrome® system with the colors cyan, magenta, yellow, black, orange and green.
It is known that colorants may have a long-term effect on the triboelectric charging of toners. As a result, it is normally not possible simply to add the colorants to a toner base formulation once prepared. It may instead be necessary to prepare a specific formulation for each colorant, with the nature and amount of the required charge control agent being tailored specifically. This approach is, correspondingly, laborious and in the case of color toners for process color is just another difficulty to add to those already described above.
Furthermore, it is important for practical use that the colorants possess high thermal stability and good dispersibility. Typical temperatures for incorporation of colorants into the toner resins are between 100° C. and 200° C. when using compounders or extruders. Accordingly, a thermal stability of 200° C., or even better 250° C., is a great advantage. It is also important that the thermal stability is maintained over a prolonged period (about 30 minutes) and in different binder systems. Typical toner binders are resins formed by addition polymerization, polyaddition and polycondensation, such as styrene, styrene-acrylate, styrene-butadiene, acrylate, polyester and phenol-epoxy resins, polysulfones and polyurethanes, individually or in combination.
Fundamentally there is a need for color pigments possessing a very high degree of transparency, good dispersibility and a low inherent electrostatic effect: as far as possible a neutral inherent triboelectric effect. Neutral inherent triboelectric effect means that the pigment has very little or no effect on the inherent electrostatic charging of the resin and readily follows a defined charge established by means, for example, of charge control agents.
Transparency is of great importance since, in the case of full color copies or in printing, the colors yellow, cyan and magenta are copied or printed over one another, the sequence of colors depending on the device. Consequently, if an overlying color is not sufficiently transparent, then the underlying color is unable to show through to a sufficient extent and the color reproduction is distorted. In the case of copying or printing on sheets for overhead projection use, transparency is even more important, since in this case a lack of transparency even in just one color makes the whole of the projected image gray.
The cyan shade, furthermore, is of great importance since it is used both in four-color printing and in 6- or 7-color printing.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an improved cyan pigment satisfying the above requirements for use in electrophotographic toners and developers, powder coating materials, inkjet inks, color filters, and electret fibers.
This object has surprisingly been achieved by the use of the copper phthalocyanine composition defined hereinbelow.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides for the use of a copper phthalocyanine composition consisting essentially of a compound of the formula (I)
and of a compound of the formula (II)
as a colorant in electrophotographic toners and developers, powders and powder coating materials, electret materials, inkjet inks, and color filters, wherein the compounds of the formulae (I) and (II) have a particle morphology with an average length-to-width ratio of more than 2.5:1, preferably from 3:1 to 6:1.
The relative proportions of the compound of the formula (I) to the compound of the formula (II) can fluctuate within wide limits; for example, from 0.1:99.9% by weight to 99.9:0.1% by weight. Preference is given to compositions of from 80 to 99.5% by weight of the compound of the formula (I) and from 0.5 to 20% by weight of the compound of the formula (II). Particular preference is given to compositions of from 90 to 99% by weight of the compound of the formula (I) and from 1 to 10% by weight of the compound of the formula (II).
The compound of the formula (I) is known per se (DE-A-2 432 564) and is in commerce under the designation C.I. Pigment Blue 15. The &bgr;-modification is preferred, being known under the names C.I. Pigment Blue 15:3 and 15:4. Also suitable in principle, however, are the &agr;-modification (C.I. Pigment Blue 15:1 and 15:2, from 0.5 to 1 Cl) and the,-modification (C.I. Pigment Blue 15:6).
The compound of the formula (II) is known per se and can be prepared in analogy to EP-A-0 508 704 by reacting the N-methylol-phthalimide with a phthalocyanine.
Conventional C.I. Pigment Blue 15, especially 15:3, possesses a very pronounced intrinsic triboelectric effect (e.g., U. Schlösser et al., Society of Imaging Science and Technology, 11th Congress on Advances in Non-impact Printing Technology, Hilton Head, S.C., Oct. 29-Nov. 11, 1995, Proceedings pp 110-112) which can be overcome only with great effort and in many cases only partly by means, for example, of adding charge control agents, which is very expensive.
It is novel and surprising that the phthalocyanine composition used in accordance with the invention and having the stated particle morphology possesses a
Baur Ruediger
Geisenberger Josef
Harz Andreas
Macholdt Hans-Tobias
Menzel Heidemarie
Clariant GmbH
Jackson Susan S.
Rodee Christopher
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