Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-12-11
1999-01-05
Smith, Jeffrey T.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C08F26704
Patent
active
058564071
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention is directed to a resinous composition useful as a component of toner powder, a toner powder incorporating said composition, and a method for the preparation of said composition, where the toner powder is useful in reprographic printing.
BACKGROUND OF THE INVENTION
Reprographic printing is the type of printing that is most commonly employed in plain paper copiers and printers. In reprographic printing, paper is electrostatically coated with particles of pigmented toner powder, and then transported to the nip between two rollers. Hot roll fusing is commonly used to fuse the toner powder to the paper. In hot roll fusing, the temperature of the top roll, which comes in direct contact with the unfused toner powder, is maintained at about 150.degree. C.-280.degree. C. The specific temperature depends on the machine design. The bottom roller acts as a pressure roll and is normally constructed with a resilient layer (e.g., silicone rubber). The fusing cycle of reprographic printing consists of passing the toner-covered (toned) paper through the two rollers, where the toner is softened and pressed against the paper. After passing through the rollers, the toner cools and sticks to the paper.
Two important components of toner powder are the toner resin and the colorant. Toner resin, which constitutes the majority of the toner powder formulation, acts as a binder. That is, the toner resin serves to bind the colorant to the paper. The toner should fix, i.e., develop some binding character, to the paper at the relatively low temperature attained during the initial stage of the fusing cycle. Whether this will occur is largely dependent on the melt characteristics of the toner resin.
In addition, the toner should not offset to the top roll at the higher temperatures attained toward the end of the fusing cycle. Any toner which offsets to the hot roll eventually contaminates the pressure roll and subsequent copies. Again, the melt characteristics of the toner resin will influence whether offset occurs. To minimize toner contamination of the hot roll, the roll is typically coated with a "non-sticking" layer, e.g., a fluorocarbon polymer, or is continually wetted with silicone oil. However, the non-sticking layer provides only a partial solution to the offset problem, and toner resin manufacturers have put considerable effort into designing resins that eliminate offset.
Two types of toner resin designs have been used to solve the offset problem. The first employs partially crosslinked, also known as gelled, resins. These resins obtain a high melt viscosity through having a partially crosslinked (gel) polymeric structure. These resins are typically produced by water-based suspension or emulsion, free radical-initiated, polymerization of ethylenically unsaturated monomers, as described for example in U.S. Pat. No. Reissue 31,072 of T. A. Jadwin et al., assigned to Eastman Kodak Company. These partially crosslinked or gelled resins cannot be made via solution polymerization, i.e., starting with the monomers dissolved in organic solvent, because of the insolubility of the product resin in the organic reaction solvent.
Although crosslinked resins are helpful in reducing offset, their presence in a toner formulation is detrimental to the initial fixing of the toner. To counter this, toner manufacturers add low molecular weight resins to their formulations. However, macrophases of crosslinked resin and low molecular weight resin often result, due to the difficulty in obtaining adequate mixing. This inhomogeneity adversely affects toner performance and reproducibility. To obtain a homogeneous blend of crosslinked and low molecular weight resins, the low molecular weight resin can be mixed with the monomers used to prepare the crosslinked resin, prior to initiating the water-based suspension polymerization process that is commonly employed to prepare the crosslinked resin. However, by either approach, one needs to independently prepare and isolate the low molecular weight polymer, and this adds ad
REFERENCES:
patent: 4146590 (1979-03-01), Yamamoto et al.
patent: 4382128 (1983-05-01), Li
patent: 5684090 (1997-11-01), Chupka, Jr.
Cheng Wu C.
Image Polymers Company
Smith Jeffrey T.
LandOfFree
Process for making bimodul, cross-linked toner resin does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for making bimodul, cross-linked toner resin, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for making bimodul, cross-linked toner resin will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-863082