Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
1999-12-14
2002-03-26
Wu, Shean C. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
C430S105000, C430S137100, C430S627000, C106S031130, C106S031270, C347S100000, C523S334000, C523S335000
Reexamination Certificate
active
06361916
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to new compositions, elements and processes. More specifically, the compositions of the present invention are dispersions of hydrophobic latex polymer particles having associated therewith both a dye and a stabilizer for the dye. Processes for making the composition and methods for making various elements using the compositions form other aspects of the invention.
DESCRIPTION RELATIVE TO THE PRIOR ART
Dyes are often unstable to light. Dyes which absorb in the infrared region are particularly susceptible to light fade. These dyes degrade more rapidly under light due to the fast reaction of the excited dye with reactive oxygen species. This degradation renders them useless for most applications without the presence of a stabilizer. When a dye is used to carry a data element, the degradation of this dye eventually results in the inability to retrieve the data element.
Dye stabilization is well known in the art. Mitsubishi Kasai (EP 0 483 387 A1) and TDK Corp. (U.S. Pat. No. 4,713,314) describes the use of cyanine dyes combined with metal stabilizers. Nickel formazan dyes have been described by Kodak as stabilizers for infrared dyes (U.S. Pat. No. 5,547,728). Additionally, metal dithiolene dyes alone have been disclosed as useful stable dyes for barcoding applications by Kodak (U.S. Pat. No. 4,753,923).
It is believed that the mechanism for most stabilization requires the close intimate contact of the stabilizer with the dye. In conventional systems, the dye and stabilizer materials are useful when they are coated together in relatively high concentration. Alternatively, relatively lower concentration of infrared absorbing dye can be used when a high stabilizer to dye ratio can be tolerated. The prior art is mainly directed to thin films of dye and stabilizer where residual color from these dyes is not detrimental. Examples of these types of application include CD storage media and thermal transfer donor elements.
However, in some applications only a low total concentration of dye and stabilizer can be tolerated. In particular, when dyes are needed at levels where they are invisible to the naked eye, high dilution of the dye and stabilizer are required. This, in turn, reduces the interaction between the dye and stabilizer. Especially in the case were ink jet printing is used to apply the dye to a print and the ink solution is relatively dilute, the stabilization effect is small.
There are several reasons why one might want to apply an infrared dye containing composition to the surface of an element carrying a photographic image. For example, a protective overcoat including the infrared absorbing dye can be applied as a final overcoat to assist in the stabilization of the underlying dye stability in an inkjet print. In another embodiment, information can be encoded using an infrared absorbing ink that is invisible to the naked eye over the surface of a photographic print. The information that is in coated on the surface of the print can be, for example, sound information and the like. The sound information can be encoded for example using barcoding, or some other form of the digital encoding. The surface of the print can then be “played” using a suitable infrared dye detecting apparatus.
Loaded latex particles are known for use in a variety of photographic and nonphotographic applications. For example, in U.S. Pat. No. 4,237,194 there is described in antistatic composition that uses a polyaniline salt loaded on a polymer latex particle. Coating of the latex composition followed by drying and core lessons of the latex, produce a suitable antistatic layer. It is also known to load latex particles with fluorescent labels in immunology research. (See for example U.S. Pat. No. 4,259,313) Also, multiple fluorescent dyes can be loaded onto the same latex particle to achieve useful results (see for example U.S. Pat. Nos. 5,326,692 and 5,919,850).
U.S. Pat. No. 5,852,074 discloses the use of latex compositions for inkjet inks. U.S. Pat. No. 5,614,008 describes “invisible” inkjet inks containing IR absorbing dyes.
None of the prior art however, discloses loading both a dye and a stabilizer for the dye onto the same latex.
SUMMARY OF THE INVENTION
We have found that dyes, particularly infrared absorbing dyes, can be stabilized at relatively low overall concentrations by associating both the dye and the stabilizer on the same polymer particle. The dye and a stabilizer on the surface of the particle are in close proximity and are in high concentration on the surface of the particle. Thus, the spatial distance between the dye in the stabilizer is not influenced by dilution of the latex and subsequent application to the surface of an element, such as a photographic element. Thus, according to the invention, there is provided a composition which is a latex having water as a continuous phase and, as the dispersed phase, hydrophobic polymer particles having associated therewith both a dye and a stabilizer.
In another aspect of the present invention, there is provided an inkjet ink that includes a composition of the invention wherein the dye is an infrared absorbing dye.
In another aspect of the invention, there is provided a photographic element having on the surface thereof, a coalesced latex of the invention wherein the dye is an infrared absorbing dye. Preferably, the coalesced latex forms a pattern representing digital information. The digital information is preferably sound information.
In another aspect of the invention, there is provided a process for associating the dye and stabilizer with the polymer particles in the latex. The process comprises the steps of:
(1) forming a solution by dissolving a dye and a stabilizer in a water miscible organic solvent,
(2) forming a latex by dispersing hydrophobic polymer particles in an aqueous continuous phase,
(3) blending the latex with the solution, and
(4) loading of the polymer particles by removing the organic solvent thereby forming a latex having the dye and stabilizer associated therewith.
In another aspect of the invention there is provided a process for producing a photographic element having on the surface thereof a digital pattern of the coalesced latex of the invention comprising the steps of:
(1) applying the latex in a digital pattern to the surface of the photographic element by inkjet printing, and
(2) coalescing the latex.
DETAILED DESCRIPTION OF THE INVENTION
The compositions of this invention provide a number of advantages over the prior art. One advantage is the ability to provide for good light stability at low overall concentrations of dyes and stabilizers. Where the dye is an infrared absorbing dye, this can result in the dyes, when applied to the surface of the photographic element, being stable yet invisible to the naked eye. In particular preferred embodiments the gloss of the invisible coalesced latex can be matched with the gloss of the underlying photographic element so as to afford near optimum print quality. Another advantage is that by using a latex of the invention, dye aggregation is minimized. Another advantage is that certain dyes that are otherwise unsuitable, for example because of their low solubility, can now be provided in stable form in compositions and in coated elements.
According to the present invention, the dye and the stabilizer must be “associated with” the hydrophobic latex particles in the composition. By “associated with” we mean that both the dye and the stabilizer are attached to or located within the polymer particle. That is, the dye and stabilizer are not merely mixed or dispersed with the latex dispersion as is known in the art, but must become a part of the individual polymer particles. That is, substantially all of the dye and stabilizer in the coating composition must be adsorbed, absorbed or otherwise become an integral part of the polymer particles. Reference is made to the following U.S. Pat. Nos.: 4,199,363; 4,304,769; 4,401,787; 5,558,908; 5,594,047.
A broad range of organic soluble dyes and stabilizers can be loaded onto polymer par
Chen Huijuan D.
Chen Tien-Teh
Williams Kevin W.
Eastman Kodak Company
Hawley J. Jeffrey
Wu Shean C.
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