Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-02-28
2004-03-30
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...
C399S336000, C430S110200, C430S097000
Reexamination Certificate
active
06713222
ABSTRACT:
BACKGROUND
The present invention is generally directed to processes for hardening toner based xerographic images for use in packaging media. In embodiments, the present invention is directed to the ultraviolet light assisted post curing of xerographic images comprised of xerographic toners wherein the toners are comprised of, for example, an unsaturated resin, colorant and various additives to thereby render the images with anti-offset properties when heat and pressure is applied, such as in packaging applications. In a specific embodiment of the present invention, the post ultraviolet light assisted curing results in the crosslinking of the toner image thereby resulting in an improved hot-offset performance, such as from about 180° C. to 240° C., and high toner elasticity, such as from about 106 poise to about 108 poise at a temperature of from about 180° C. to about 200° C., as measured by thermometer at a shear frequency of from about 10 to about 100 radian per second, and which cured crosslinked toner images are useful in packaging applications wherein xerographic images on a variety of substrates can then be heat sealed onto containers, such as plastic bottles, and the like. A xerographic engine can be utilized in marking images on, for instance, an aluminum foil substrate with a toner comprised of an unsaturated resin, colorant and toner additives fused by either a contact or non-contact fuser. These images are then hardened by exposure to ultraviolet light causing the unsaturated resin in the toner to be crosslinked, and whenever the hardened images can then be heat and pressure sealed onto containers, such as for example, pharmaceutical bottles, food containers such as yogurt cups and the like, without or minimal image offset, or transported onto pressure sealing devices. An overcoating lacquer comprised of an ultraviolet initiator and optionally an unsaturated monomer can be applied or coated onto the xerographic image, followed by the application of ultraviolet light to harden the image on a substrate like paper.
REFERENCES
Electrophotographic toners are generally comprised of a resin, such as a styrene-acrylate or polyester, a colorant and optionally a charge control agent. Many various toner formulations are known, and more specifically, one toner formulation is comprised of an unsaturated polyester resin, such that desirable low fixing temperatures and offset properties are attained, reference, for example, U.S. Pat. No. 5,227,460, the disclosure of which is totally incorporated herein by reference, and wherein there is illustrated the unsaturated polyester resin poly(propoxylated bisphenol co-fumarate) which is branched to a gel content of up to about 40 weight percent utilizing a peroxide to provide a toner useful for electrophotographic processes.
In U.S. Pat. No. 3,590,000, an unsaturated polyester for use as a toner binder is disclosed. Similarly, in U.S. Pat. No. 4,331,755, there is disclosed an unsaturated polyester resin derived from fumaric acid and a polyol blend of propoxylated bisphenol. Additionally, U.S. Pat. No. 4,525,445, discloses an unsaturated polyester resin derived from fumaric acid, isophthalic acid and a polyol blend of propoxylated bisphenol. The aforementioned unsaturated polyester resins can be utilized, for example, as a toner binder, especially for xerographic copiers and printers. Other patents of that may be of interest are U.S. Pat. Nos. 4,788,122; 5,466,554, 5,686,218; 4,988,794; 4,727,011; 4,533,614 and 5,366,841. The disclosures of all the patents are totally incorporated herein by reference.
Ultraviolet-hardenable printing inks for use in flexographic printing forms are disclosed in U.S. Pat. Nos. 5,948,594 and 5,972,565, the disclosures of which are totally incorporated herein by reference, and wherein a photopolymerizable printing plate and ultraviolet printing inks are disclosed. Ultraviolet curable epoxy-polyester powder paints are disclosed in U.S. Pat. No. 4,129,488, the disclosure of which is totally incorporated herein by reference, wherein there is illustrated powder paint coatings comprised of ethylenically unsaturated polymers.
U.S. Pat. No. 5,275,918, the disclosure of which is totally incorporated herein by reference, discloses an ultraviolet curable heat activatable transfer toner, and more specifically, a nonelectroscopic prolonged toner comprising (i) an ultraviolet curable, epoxy-containing, copolymer comprising a first monomer and a second monomer wherein the second monomer is selected from the group consisting of glycidyl methacrylate and glycidyl acrylate, and wherein the copolymer possesses an average molecular of about 100 to about 10,000 and is present in an amount of about 10 to about 50 percent by weight based on the total toner weight; (ii) a solid plasticizer present in an amount of from about 50 to about 90 percent by weight based on the total toner weight; and (iii) a photoinitiator present in an amount of about 0.5 to about 15 percent by weight based on the total toner.
In U.S. Pat. No. 4,110,187, the disclosure of which is totally incorporated herein by reference, there is illustrated, for example, a radiation composition of a solution of a polyester resin and a solvent containing an ethylenic unsaturated photopolymerizable compound.
In U.S. Pat. Nos. 5,049,646 and 5,102,762, the disclosures of which are totally incorporated herein by reference, there are disclosed polyesters and ultraviolet toners thereof wherein the toner particles are useful in photolithographic applications and wherein ultraviolet light is used for generating printing plates from color separation transparencies which contain imaged areas defined by the toner particles.
In a number of xerographic engines and processes, the toner image is fused on a substrate, such as paper or a transparency, by heating the toner with a contact fuser or a non-contact fuser, and wherein the transferred heat melts the toner mixture onto the substrate. When a resin is highly branched or crosslinked, such as about 40 to about 65 percent, higher temperatures can be used to melt the toner mixture, and in some instances, when the crosslinking level is too high, then the toner mixture usually will not melt and may even decompose before melting. Thus, to retain the energy of the xerographic engine to a minimum, such as at a low fusing temperature of from about 125° C. to about 145° C., it is desirable to utilize low, for example toners which fuse at from about 125° C. to about 145° C., and wherein less heat is utilized during the fusing of the image on paper. However, such low melting toner mixtures may not be as effective for use in packaging, especially wherein heat and pressure devices are utilized to seal these substrate images onto packages. Hence a process is needed to overcome this disadvantage, and more specifically, a method or process wherein a low melting toner is utilized to generate a xerographic image, and wherein the xerographic image is hardened on the substrate by, for example, use of an ultraviolet light source, and also wherein an overcoating lacquer may be included on the substrate, which lacquer can be comprised of an ultraviolet initiator and/or unsaturated monomers, causing the unsaturated resin in the toner to crosslink and which enables its effective use in packaging applications wherein heat and pressure devices are utilized to seal the xerographic image substrate on various packaging containers.
SUMMARY
It is a feature of the present invention to provide processes utilizing a low melting toner comprised of an unsaturated resin, colorant and toner additives.
It is another feature of the present invention to provide xerographic images on a variety of substrates, such as paper, MYLAR® or an aluminum foil, and wherein the xerographic image is comprised of a toner comprised of an unsaturated resin and colorant.
In yet another feature of the present invention, there are provided processes for hardening xerographic images, such as by ultraviolet light, which enables the toner resin to crosslink.
Moreover, it is a feature of the present
Gutman Edward J.
Sacripante Guerino G.
Fay Sharpe Fagan Minnich & McKee LLP
Rodee Christopher
Xerox Corporation
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