Patent Application
20070277690
For a better understanding of the present invention, reference may be had to the accompanying figures.
Disclosed herein are fuser agents, release agents, fuser oils, and the like, comprising perfluorinated polyethers. The release agents are useful with toner-based printing and copying apparatuses, and with ink (such as solid ink)-based printing and copying apparatuses. Specifically, the release agent comprises a functional perfluorinated polyether (PFPE) fluid to improve the wettability of PFPE on a variety of surfaces. A functional fluid can also be blended with a non-functional PFPE, to be used in a variety of release agent applications.
Ink jet printing systems using intermediate transfer, transfix or transfuse members are well known, such as that described in U.S. Pat. No. 4,538,156. Generally, the transfix printing or intermediate transfer member is employed in combination with a print head. A final receiving surface or print medium is brought into contact with the transfix printing surface after the image has been placed thereon by the nozzles of the print head. The image is then transferred and fixed to a final receiving surface.
The imaging member is multi-functional. First, the ink jet print head prints images on the imaging member, and thus, it is an imaging member. Second, after the images are printed on the imaging member, they can then be transfixed or transfused to a final print medium. Therefore, the imaging member provides a transfix or transfuse function, in addition to an imaging function.
The details of embodiments of phase-change ink printing processes are described in the patents referred to above, such as U.S. Pat. Nos. 5,502,476; 5,389,958; and 6,196,675 B1, the disclosures of each of which are hereby incorporated by reference in their entirety.
Referring to
The ink used in the printing process can be a phase change ink, such as, for example, a solid ink. The term “phase change ink” means that the ink can change phases, such as a solid ink becoming liquid ink or changing from solid into a more malleable state. Specifically, in embodiments, the ink can be in solid form initially, and then can be changed to a molten state by the application of heat energy. The solid ink may be solid at room temperature, or at about 25° C. The solid ink may possess the ability to melt at relatively high temperatures above from about 85° C. to about 150° C. The ink is melted at a high temperature and then the melted ink 6 is ejected from print head 7 onto the liquid layer 2 of imaging member 3. The ink is then cooled to an intermediate temperature of from about 20° C. to about 80° C., or about 72° C., and solidifies into a malleable state in which it can then be transferred onto a final receiving substrate 8 or print medium 8.
The ink has a viscosity of from about 5 to about 30 centipoise, or from about 8 to about 20 centipoise, or from about 10 to about 15 centipoise at about 140° C. The surface tension of suitable inks is from about 23 to about 50 dynes/cm. Examples of suitable inks for use herein include those described in U.S. Pat. Nos. 4,889,560; 5,919,839; 6,174,937; and 6,309,453, the disclosure each of which are hereby incorporated by reference in their entirety.
Some of the liquid layer 2 is transferred to the print medium 8 along with the ink. A typical thickness of transferred liquid is about 100 angstroms to about 100 nanometer, or from about 0.1 to about 200 milligrams, or from about 0.5 to about 50 milligrams, or from about 1 to about 10 milligrams per print medium.
Suitable liquids that may be used as the transfix print liquid surface 2 include water, fluorinated oils, glycol, surfactants, mineral oil, silicone oil, functional oils, and the like, and mixtures thereof. Functional liquids include silicone oils or polydimethylsiloxane oils having mercapto, fluoro, hydride, hydroxy, and the like functionality.
Feed guide(s) 10 and 13 help to feed the print medium 8, such as paper, transparency or the like, into the nip 9 formed between the pressure member 11 (shown as a roller), and imaging member 3. It should be understood that the pressure member can be in the form of a belt, film, sheet, or other form. In embodiments, the print medium 8 is heated prior to entering the nip 9 by heated feed guide 13. When the print medium 8 is passed between the transfix printing medium 3 and the pressure member 11, the melted ink 6 now in a malleable state is transferred from the imaging member 3 onto the print medium 8 in image configuration. The final ink image 12 is spread, flattened, adhered, and fused or fixed to the final print medium 8 as the print medium moves between nip 9. Alternatively, there may be an additional or alternative heater or heaters (not shown) positioned in association with offset printing apparatus 1. In another embodiment, there may be a separate optional fusing station located upstream or downstream of the feed guides.
The pressure exerted at the nip 9 is from about 10 to about 1,000 psi, or about 500 psi, or from about 200 to about 500 psi. This is approximately twice the ink yield strength of about 250 psi at 50° C. In embodiments, higher temperatures, such as from about 72 to about 75° C. can be used, and at the higher temperatures, the ink is softer. Once the ink is transferred to the final print medium 8, it is cooled to an ambient temperature of from about 20° C. to about 25° C. Stripper fingers (not shown) may be used to assist in removing the print medium 8 having the ink image 12 formed thereon to a final receiving tray (also not shown).
Examples of the outer surface of the imaging system members include silicone, urethane, fluoroplastic or fluoropolymers, fluoroelastomers, or silicone-fluoropolymer hybrids. Specifically, suitable fluoroelastomers are those described in detail in U.S. Pat. Nos. 5,166,031, 5,281,506, 5,366,772 and 5,370,931, together with U.S. Pat. Nos. 4,257,699, 5,017,432 and 5,061,965, the disclosures each of which are incorporated by reference herein in their entirety. As described therein, these elastomers are from the class of 1) copolymers of two of vinylidenefluoride, hexafluoropropylene, and tetrafluoroethylene; 2) terpolymers of vinylidenefluoride, hexafluoropropylene and tetrafluoroethylene; and 3) tetrapolymers of vinylidenefluoride, hexafluoropropylene, tetrafluoroethylene and cure site monomer. These are known commercially under various designations as VITON A®, VITON B®, VITON E®, VITON E 60C®, VITON E430®, VITON 910®, VITON GH®; VITON GF®; and VITON ETP®. The VITON® designation is a Trademark of E.I. DuPont de Nemours, Inc. The cure site monomer can be 4-bromoperfluorobutene-1,1,1-dihydro-4-bromoperfluorobutene-1,3-bromoperfluoropropene-1,1,1-dihydro-3-bromoperfluoropropene-1, or any other suitable, known cure site monomer commercially available from DuPont. Other commercially available fluoropolymers include FLUOREL 2170®, FLUOREL 2174®, FLUOREL 2176®, FLUOREL 2177® and FLUOREL LVS 76®, FLUOREL® being a Trademark of 3M Company. Additional commercially available materials include AFLAS™ a poly(propylene-tetrafluoroethylene) and FLUOREL II® (LII11900) a poly(propylene-tetrafluoroethylenevinylidenefluoride) both also available from 3M Company, as well as the Tecnoflons identified as FOR-60KIR®, FOR-LHF®, NM® FOR-THF®, FOR-TFS®, TH®, and TN505®, available from Montedison Specialty Chemical Company.
The fluoroelastomers VITON GH® and VITON GF® have relatively low amounts of vinylidenefluoride. The VITON GF® and Viton GH® have about 35 weight percent of vinylidenefluoride, about 34 weight percent of hexafluoropropylene and about 29 weight percent of tetrafluoroethylene with about 2 weight percent cure site monomer.
The amount of fluoroelastomer compound in solution in the outer layer solutions, in weight percent total solids, is from about 10 to about 25 percent, or from about 16 to about 22 percent by weight of total solids. Total solids as used herein include the amount of fluoroelastomer, dehydrofluorinating agent and optional adjuvants and fillers, including metal oxide fillers.
In addition to the fluoroelastomer, the outer layer may comprise a fluoropolymer or other fluoroelastomer blended with the above fluoroelastomer. Examples of suitable polymer blends include the above fluoroelastomer, blended with a fluoropolymer selected from the group consisting of polytetrafluoroethylene and perfluoroalkoxy. The fluoroelastomer can also be blended with non-fluorinated ethylene or non-fluorinated propylene.
Specific examples of outer coatings include those listed in U.S. Pat. Nos. 6,910,765; 6,918,664; 6,843,559; 6,932,470; 6,648,467 and 6,939,000, the disclosures of each of these are incorporated by reference herein in their entirety.
Other coatings suitable for the outer layer include an outer coating comprising an elastomer comprising monomers selected from the group consisting of halogenated monomers, polyorganosiloxane monomers, and polymers thereof. The elastomer is selected from the group consisting of volume grafted fluoroelastomers, ceramers, grafted ceramers, titamers and grafted titamers. The elastomer can also comprises polyorganosiloxane monomers, such as those comprising functionality selected from the group consisting of vinyl, alkoxy and hydrogen functionality, or the elastomer can comprise an additional monomer capable of reacting with said polyorganosiloxane monomer to form a polyorganosiloxane copolymer. For example, the polyorganosiloxane copolymer can be selected from the group consisting of polyamide polyorganosiloxane copolymers, polyimide polyorganosiloxane copolymers, polyester polyorganosiloxane copolymers, polysulfone polyorganosiloxane copolymers, polystyrene polyorganosiloxane copolymers, polypropylene polyorganosiloxane copolymers, and polyester polyorganosiloxane copolymers.
Other suitable outer layers include a thermoplastic such perfluoroalkoxy, polyimide, perfluorovinylalkylether tetrafluoroethylene, polyether, polyester, polypropylene, vinylidene fluoride, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, poly(vinyl fluoride), polychlorotrifluoroethylene, and mixtures thereof. The polyesters include polyester polydiorganosiloxane, poly(ethylene terephthalate), poly(butylene terephthalate), poly(ethylene naphthoate), and mixtures thereof. Specific polyethers include those is selected from the group consisting of polyether ether ketone, poly(phenylene ether), polyether sulfone, and mixtures thereof. Suitable polypropylenes include poly(ethylene propylene), polystyrene, polyphenylene oxide, and mixtures thereof. Other thermoplastics include a polyvinylidene halide such as those selected from the group consisting of polyvinylidene fluoride and polyvinylidene chloride. Thermoplastics also include polyimides such as polyamideimide, fluorinated polyimide, polyimidesulfone, polyimide polyorganosiloxane, and polyimide ether, and polyamideimide.
Other suitable outer layers include a thermoset such as ceramics and silicones, and include those thermosets selected from the group consisting of thermoset rubbers, urethenes, phenolics, epoxies, alkyds, and mixtures thereof.
Other suitable outer layers include fluorosilicones.
An inorganic particulate filler may be used in connection with the fluoroelastomer outer layer, in order to provide anchoring sites for the functional groups of the silicone release agent. However, a filler is not necessary for use with the present fluorosilicone release agent. In fact, dispensing with a metal oxide increases imaging member life and decreases fabrication costs. Examples of suitable fillers include a metal-containing filler, such as a metal, metal alloy, metal oxide, metal salt or other metal compound. The general classes of metals, which are applicable to the present invention include those metals of Groups 1b, 2a, 2b, 3a, 3b, 4a, 4b, 5a, 5b, 6b, 7b, 8 and the rare earth elements of the Periodic Table. The filler can be an oxide of aluminum, copper, tin, zinc, lead, iron, platinum, gold, silver, antimony, bismuth, zinc, iridium, ruthenium, tungsten, manganese, cadmium, mercury, vanadium, chromium, magnesium, nickel and alloys thereof. Other specific examples include inorganic particulate fillers are aluminum oxide and cupric oxide. Other examples include reinforcing and non-reinforcing calcined alumina and tabular alumina, respectively, along with nanoparticles. The size of the particle may be such that a low weight percent of loading into the polymer coating will provide a higher surface area of contact between the polymer and the filler, providing enhanced reinforcement or functionality.
The thickness of the outer fluoroelastomer surface layer of the imaging member herein is from about 10 to about 250 micrometers, or from about 15 to about 100 micrometers.
Optional intermediate adhesive layers and/or intermediate polymer or elastomer layers may be applied to achieve desired properties and performance objectives of the present invention. The intermediate layer may be present between the substrate and the outer fluoroelastomer surface. An adhesive intermediate layer may be selected from, for example, epoxy resins and polysiloxanes. Examples of suitable intermediate layers include silicone rubbers such as room temperature vulcanization (RTV) silicone rubbers; high temperature vulcanization (HTV) silicone rubbers and low temperature vulcanization (LTV) silicone rubbers. These rubbers are known and readily available commercially such as SILASTIC® 735 black RTV and SILASTIC® 732 RTV, both from Dow Corning; and 106 RTV Silicone Rubber and 90 RTV Silicone Rubber, both from General Electric. Other suitable silicone materials include the siloxanes (such as polydimethylsiloxanes); fluorosilicones such as Silicone Rubber 552, available from Sampson Coatings, Richmond, Va.; liquid silicone rubbers such as vinyl crosslinked heat curable rubbers or silanol room temperature crosslinked materials; and the like. Another specific example is Dow Corning Sylgard 182.
There may be provided an adhesive layer between the substrate and the intermediate layer. There may also be an adhesive layer between the intermediate layer and the outer layer. In the absence of an intermediate layer, the fluoroelastomer layer may be bonded to the substrate via an adhesive layer.
The thickness of the intermediate layer is from about 0.5 to about 20 mm, or from about 1 to about 7 mm.
The release agents or fusing oils described herein are provided onto the outer layer of the imaging member via a delivery mechanism such as a delivery roll. The delivery roll is partially immersed in a sump, which houses the fuser oil or release agent. The oil is renewable in that the release oil is housed in a holding sump and provided to the imaging member when needed, optionally by way of a release agent donor roll in an amount of from about 0.1 to about 20 mg/copy, or from about 1 to about 12 mg/copy, or from about 1 to about 5 mg/copy. The later range encompasses most solid ink and lower oil levels in some applications.
Examples of suitable release agents include those having the following skeletal Formulas I or II:
CF3—(CF2CF2)m—O—(R1R2O)—(R3R3O)n—(R3O)p—(CF2)q—CF3 Formula I
wherein R1 is CF2, CF—CF3 or —NHR4; R2 is CF2, CF—CF3, or —NR4R5; and R3 is CF2 or CF3, wherein R1 is selected from the group consisting of CF2, CF—CF3 or —NR4R5; R2 is selected from CF2 or CF—CF3; R3 is CF2 or CF3; R4 is selected from the group consisting of hydrogen, alkyl group having from about 1 to about 18 carbon atoms or from about 1 to about 8 carbons or from about 1 to about 6 carbons or from about 1 to about 3 carbon atoms, arylalkyl group (with either the alkyl group or the aryl group being attached to the silicon atom) having from about 7 to about 18 carbon atoms or from about 7 to about 9 carbon atoms, mercapto, hydride or carbinol functional group; R5 is selected from the group consisting of alkyl having from about 1 to about 20 carbons or from about 1 to about 10 carbons such as methyl, ethyl, butyl and the like, and a fluoroalkyl having from about 2 to about 10 carbons such as fluoromethyl, fluorobutyl, difluoroethyl, and the like; m is a number of 0 or 1; n is a number of from about 0 to about 500, or from about 200 to about 350; p is a number of from about 0 to about 100 or from about 50 to about 75; q is a number of 0 or 1; and p+n is a number of from about 180 to about 500 or from about 250 to about 425; and
R1—(CF2CF2)m—O—(R2R2O)n—(R2O)p—(CF2)q—CF3—R1 Formula II
wherein R1 is CF3; R2 is selected from the group consisting of CF2 and CF—CF3; m is a number of 0 or 1; n is a number of from about 0 to about 500, or from about 200 to about 350; p is a number of from about 0 to about 100 or from about 50 to about 75; q is a number of 0 or 1; and p+n is a number of from about 180 to about 500 or from about 250 to about 425. The alkyl groups above can include including linear, branched, cyclic, and unsaturated alkyl groups.
In embodiments, the release agent has a viscosity of from about 75 to about 1,500 cS, or from about 100 to about 1,000 cS, when the release agent is used with toner. When the release agent is used with a phase change ink, the viscosities are from about 50 to about 200 cS, or from about 10 to about 40 cS.
Alternatively, a blend of functional silicone materials and nonfunctional perfluorinated polyether release agent can be used to combine the advantages of both individual fluids. In embodiments, a functional element can be added to the PFPE fluids in order to provide a replenishable, consistently uniform and non-interactive release fluid for use on variety of surfaces. In embodiments, the use of amine-functional PFPE fluids enables initial wetting performance and potentially sustained performance as this would also improve the wetting behavior of PFPE fluids so that they might wet areas of the imaging member that have been contaminated with ink. This should not, however, compromise the non-interactive nature of the PFPE fluid as the functional level would likely be very low in relation to the overall fluid composition. This concept should be applicable to other systems where a fluoroelastomer surface is used in conjunction with a release fluid and where there is a component of the toner or ink that is soluble in or capable of reacting with silicone oil. The use of functional PFPE release fluids is promising in a wide variety of technologies as it could further reduce problematic side-reactions with ink, ink additives, paper debris, and the like elements that lead to early failure in marking subsystems.
In embodiments wherein a blend is used, the non-functional PFPE is used in an amount of from about 99 to about 60, or from about 90 to about 70 percent, or from 90 to about 80 percent by weight in combination with the functional fluorinated material. Similarly, the functional PFPE component is used in amounts of from about 1 to about 40 percent, or from about 10 to about 30 percent, or from about 10 to about 20 percent weight in combination with the non-functional PFPE material.
The combination of non-functional PFPE and functional PFPE fluid shows little interaction of the substituents to the copy substrate, such as paper. In this manner, the release agents do not prevent adhesives and POST IT® notes and other tabs from adhering adequately to copies or prints fused with these fluorinated release agents. In addition, the release agents spread better than known release agents on silicone rubber surfaces, and prevent swelling, which is a common problem. Moreover, the use of functional PFPE oils with non-functional PFPE oils reduces costs.
A nonfunctional oil, as used herein, refers to oils that do not interact or chemically react with the surface of the imaging member or with fillers on the surface. A functional oil, as used herein, refers to a release agent having functional groups, which chemically react with the fillers present on the surface of the imaging member or with the polymer itself, so as to reduce the surface energy of the fillers so as to provide better release of ink particles from the surface of the imaging member. If the surface energy is not reduced, the ink particles will tend to adhere to the imaging roll surface or to filler particles on the surface of the imaging roll, which will result in copy quality defects.
All the patents and applications referred to herein are hereby specifically, and totally incorporated herein by reference in their entirety in the instant specification.
The following Examples further define and describe embodiments of the present invention. Unless otherwise indicated, all parts and percentages are by weight.
Preparation of Functional Fluids
A perfluoropolyether fluid may be prepared or modified via several known synthetic methodologies in order to obtain pendant chemical structures relevant for enhancing the affinity of the fluid for various imaging member surfaces. The affinity between the functional pendant group may be obtained via polarity, charged ion or chemical bonding interactions. The desired chemical functional level in the concentrated fluid is from about 0.1 to about 2.0 mole percent. Lower values of from about 0.1 to about 0.5 mole percent fluids may not be diluted to functional levels desirable for the release agent application.
Blended Fluid Composition
A prepared functional fluid concentrate fluid may be diluted with a non-functional fluid for the purpose of tailoring viscosity or functional level to a level appropriate for the intended application. Suitable blending fluids are sold under the trade names Krytox®, Fomblin®, Galden® or similarly available PFPE or fluorinated fluids. An example is a functional concentrated PFPE fluid of approximately 400 cS at 25° C. made to a functional level of 1.0 mole percent blended with a 400-800 cS at 25° C. non-functional PFPE fluid at a 1:9 ratio by weight. The resulting fluid has a viscosity of approximately 600 cS at 25° C. and a functional level of 0.1 mole percent.
Functional PFPE Fluid Blend Use as Release Agent in Phase Chance Ink Application
A fluid as fabricated in Examples 1 or 2 may be delivered to an imaging drum member or other imaging member for the purpose of maintaining separation between an imaging drum surface in continuous and variable contact with ink or ink components and those ink or ink components during printing operation. This fluid can be delivered to the desired surface by several known methods for delivering release agents in printing, providing superior results than currently employed release agents.
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.
Reference is made to co-pending, commonly assigned U.S. Patent Application Attorney Docket No. 20051761, entitled “Perfluorinated Polyether Release Agent for Fuser Members.” The application is hereby incorporated by reference in its entirety.
