Patent Publication Number: US-8541108-B2

Title: Fuser member

Description:
BACKGROUND 
     1. Field of Use 
     This disclosure is generally directed to fuser members useful in electrophotographic imaging apparatuses, including digital, image on image, and the like. In addition, the fuser member described herein can also be used in a transfix apparatus in a solid ink jet printing machine. 
     2. Background 
     Centrifugal molding is used to obtain seamless polyimide belts useful as fuser members. Typically, a thin fluorine or silicone release layer is applied to the inner surface of a rigid cylindrical mandrel. A polyimide coating is applied to the inner surface of the mandrel containing the release layer. The polyimide is cured and then released from the mandrel. 
     There are drawbacks to this process. The length of the polyimide belt is determined by the size of the mandrel. The requirement of a release layer on the inner surface of the mandrel is an additional process step. For fuser belts manufactured in this manner the cost is expensive. There is a need to reduce the cost. 
     In addition, a polyimide fuser belt requires a modulus that is greater than 6000 MPa. It is preferable the onset decomposition temperature be greater than 500° C. Such requirements, along with reduced cost of manufacturing are desirable. 
     SUMMARY 
     According to an embodiment, a fuser member is provided. The fuser member includes a substrate layer comprising a polyimide polymer and a hydroxyl terminated polybutadiene. 
     According to another embodiment, there is described a fuser member including a substrate layer comprising a polyimide polymer and a hydroxyl terminated polybutadiene. Disposed on the substrate layer is a silicone intermediate layer. A fluoropolymer release layer is disposed on the intermediate layer. 
     According to another embodiment there is provided a method of forming a fuser belt suitable for use with an image forming system. The method includes flow coating a composition of a polyimide, hydroxyl terminated polybutadiene and a solvent onto an outer surface of a rotating substrate. The coating is partially cured at a temperature of from about 125° C. to about 190° C. for a time of from about 30 to about 90 minutes to form a belt. The partially cured belt is removed from the rotating substrate. The partially cured belt is tensioned and rotated at a temperature of from about 250° C. to about 370° C. for a time of from about 30 to about 90 minutes to cure the belt. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the present teachings and together with the description, serve to explain the principles of the present teachings. 
         FIG. 1  depicts an exemplary fusing member having a belt substrate in accordance with the present teachings. 
         FIGS. 2A-2B  depict exemplary fusing configurations using the fuser belt shown in  FIG. 1  in accordance with the present teachings. 
         FIG. 3  depicts a fuser configuration using a transfix apparatus. 
         FIG. 4  depicts a tensioning of a fusing member for final curing. 
     
    
    
     It should be noted that some details of the FIGS. have been simplified and are drawn to facilitate understanding of the embodiments rather than to maintain strict structural accuracy, detail, and scale. 
     DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     In the following description, reference is made to the accompanying drawings that form a part thereof, and in which is shown by way of illustration specific exemplary embodiments in which the present teachings may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present teachings and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present teachings. The following description is, therefore, merely exemplary. 
     Furthermore, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” The term “at least one of” is used to mean that one or more of the listed items can be selected. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein. For example, a range of “less than 10” can include any and all sub-ranges between (and including) the minimum value of zero and the maximum value of 10, that is, any and all sub-ranges having a minimum value of equal to or greater than zero and a maximum value of equal to or less than 10, e.g., 1 to 5. In certain cases, the numerical values as stated for the parameter can take on negative values. In this case, the example value of range stated as “less than 10” can assume negative values, e.g. −1, −2, −3, −10, −20, −30, etc. 
     The fuser or fixing member can include a substrate having one or more functional intermediate layers formed thereon. The substrate described herein includes wbelt. The one or more intermediate layers include cushioning layers and release layers. Such fixing member can be used as an oil-less fusing member for high speed, high quality electrophotographic printing to ensure and maintain a good toner release from the fused toner image on an image supporting material (e.g., a paper sheet), and further assist paper stripping. 
     In various embodiments, the fixing member can include, for example, a substrate, with one or more functional intermediate layers formed thereon. The substrate can be formed in various shapes, such as a belt, or a film, using suitable materials that are non-conductive or conductive depending on a specific configuration, for example, as shown in  FIG. 1 . 
     In  FIG. 1 , the exemplary fixing or transfix member  200  can include a belt substrate  210  with one or more functional intermediate layers, e.g.,  220  and an outer surface layer  230  formed thereon. The outer surface layer  230  is also referred to as a release layer. The belt substrate  210  is described further and is made of a polyimide polymer and a hydroxyl terminated polybutadiene. 
     Functional Intermediate Layer 
     Examples of materials used for the functional intermediate layer  220  (also referred to as cushioning layer or intermediate layer) include fluorosilicones, 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; 106 RTV Silicone Rubber and 90 RTV Silicone Rubber, both from General Electric; and JCR6115CLEAR HTV and SE4705U HTV silicone rubbers from Dow Corning Toray Silicones. Other suitable silicone materials include 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. Commercially available LSR rubbers include Dow Corning Q3-6395, Q3-6396, SILASTIC® 590 LSR, SILASTIC® 591 LSR, SILASTIC® 595 LSR, SILASTIC® 596 LSR, and SILASTIC® 598 LSR from Dow Corning. The functional layers provide elasticity and can be mixed with inorganic particles, for example SiC or Al 2 O 3 , as required. 
     Other examples of the materials suitable for use as functional intermediate layer  220  also include fluoroelastomers. Fluoroelastomers 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 fluoroelastomers are known commercially under various designations such 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, such as those commercially available from DuPont. Other commercially available fluoropolymers include FLUOREL 2170®, FLUOREL 2174®, FLUOREL 2176®, FLUOREL 2177® and FLUOREL LVS 76®, FLUOREL® being a registered trademark of 3M Company. Additional commercially available materials include AFLAS™ a poly(propylene-tetrafluoroethylene), and FLUOREL II® (LII900) 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®, NH®, P757®, TNS®, T439®, PL958®, BR9151® and TN505®, available from Ausimont. 
     Examples of three known fluoroelastomers are (1) a class of copolymers of two of vinylidenefluoride, hexafluoropropylene, and tetrafluoroethylene, such as those known commercially as VITON A®; (2) a class of terpolymers of vinylidenefluoride, hexafluoropropylene, and tetrafluoroethylene known commercially as VITON B®; and (3) a class of tetrapolymers of vinylidenefluoride, hexafluoropropylene, tetrafluoroethylene, and cure site monomer known commercially as VITON GH® or VITON GF®. 
     The fluoroelastomers VITON GH® and VITON GF® have relatively low amounts of vinylidenefluoride. The VITON GF® and VITON OH® 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 thickness of the functional intermediate layer  220  is from about 30 microns to about 1,000 microns, or from about 100 microns to about 800 microns, or from about 150 to about 500 microns. 
     Release Layer 
     An exemplary embodiment of a release layer  230  includes fluoropolymer particles. Fluoropolymer particles suitable for use in the formulation described herein include fluorine-containing polymers. These polymers include fluoropolymers comprising a monomeric repeat unit that is selected from the group consisting of vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, perfluoroalkylvinylether, and mixtures thereof. The fluoropolymers may include linear or branched polymers, and cross-linked fluoroelastomers. Examples of fluoropolymer include polytetrafluoroethylene (PTFE); perfluoroalkoxy polymer resin (PFA); copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP); copolymers of hexafluoropropylene (HFP) and vinylidene fluoride (VDF or VF2); terpolymers of tetrafluoroethylene (TFE), vinylidene fluoride (VDF), and hexafluoropropylene (HFP); and tetrapolymers of tetrafluoroethylene (TFE), vinylidene fluoride (VF2), and hexafluoropropylene (HFP), and mixtures thereof. The fluoropolymer particles provide chemical and thermal stability and have a low surface energy. The fluoropolymer particles have a melting temperature of from about 255° C. to about 360° C. or from about 280° C. to about 330° C. These particles are melted to form the release layer. 
     For the fuser member  200 , the thickness of the outer surface layer or release layer  230  can be from about 10 microns to about 100 microns, or from about 20 microns to about 80 microns, or from about 40 microns to about 60 microns. 
     Adhesive Layer(s) 
     Optionally, any known and available suitable adhesive layer may be positioned between the release layer  230 , the functional intermediate layer  220  and the substrate  210 . Examples of suitable adhesives include silanes such as amino silanes (such as, for example, I-IV Primer 10 from Dow Corning), titanates, zirconates, aluminates, and the like, and mixtures thereof. In an embodiment, an adhesive in from about 0.001 percent to about 10 percent solution can be wiped on the substrate. The adhesive layer can be coated on the substrate, or on the outer layer, to a thickness of from about 2 nanometers to about 2,000 nanometers, or from about 2 nanometers to about 500 nanometers. The adhesive can be coated by any suitable known technique, including spray coating or wiping. 
       FIGS. 2A and 2B  depict an exemplary fusing configuration for the fusing process in accordance with the present teachings. It should be readily apparent to one of ordinary skill in the art that the fusing configurations  300 B and  400 B depicted in  FIGS. 2A-2B , respectively, represent generalized schematic illustrations and that other members/layers/substrates/configurations can be added or existing members/layers/substrates/configurations can be removed or modified. Although an electrophotographic printer is described herein, the disclosed apparatus and method can be applied to other printing technologies. Examples include offset printing and inkjet and solid transfix machines. 
       FIG. 2A  depicts the fusing configuration  300 B using a fuser belt shown in  FIG. 1  in accordance with the present teachings. The configuration  300 B can include a fuser belt of  FIG. 1  that forms a fuser nip with a pressure applying mechanism  335 , such as a pressure belt, for an image supporting material  315 . In various embodiments, the pressure applying mechanism  335  can be used in combination with a heat lamp (not shown) to provide both the pressure and heat for the fusing process of the toner particles on the image supporting material  315 . In addition, the configurations  300 B can include one or more external heat rolls  350  along with, e.g., a cleaning web  360 , as shown in  FIG. 2A . 
       FIG. 2B  depicts the fusing configuration  400 B using a fuser belt shown in  FIG. 1  in accordance with the present teachings. The configuration  400 B can include a fuser belt (i.e.,  200  of  FIG. 1 ) that forms a fuser nip with a pressure applying mechanism  435 , such as a pressure belt in  FIG. 2B , for a media substrate  415 . In various embodiments, the pressure applying mechanism  435  can be used in a combination with a heat lamp to provide both the pressure and heat for the fusing process of the toner particles on the media substrate  415 . In addition, the configurations  400 B can include a mechanical system  445  to move the fuser belt  200  and thus fusing the toner particles and forming images on the media substrate  415 . The mechanical system  445  can include one or more rolls  445   a - c , which can also be used as heat rolls when needed. 
       FIG. 3  demonstrates a view of an embodiment of a transfix member  7  which may be in the form of a belt, sheet, film, or like form. The transfix member  7  is constructed similarly to the fuser belt described above. The developed image  12  positioned on intermediate transfer member  1 , is brought into contact with and transferred to transfix member  7  via rollers  4  and  8 . Roller  4  and/or roller  8  may or may not have heat associated therewith. Transfix member  7  proceeds in the direction of arrow  13 . The developed image is transferred and fused to a copy substrate  9  as copy substrate  9  is advanced between rollers  10  and  11 . Rollers  10  and/or  11  may or may not have heat associated therewith. 
     Described herein is a polyimide composition suitable for use as a substrate layer  210  of  FIG. 1 . The polyimide composition includes an internal release agent that self releases from a metal substrate such as stainless steel. Most references report applying an external release layer on the metal substrate before coating the polyimide layer, and then releasing it. The disclosed composition is cost effective since only one coating layer is needed. 
     Substrate Layer 
     The substrate layer  210  includes a polyimide composition that includes an internal release agent that self-releases from a metal substrate such as stainless steel. Typically, an external release layer is applied to the metal substrate before coating the polyimide layer, and this allows release of the polyimide. The disclosed composition is cost effective since only one coating layer is needed. 
     The disclosed polyimide substrate layer  210  possesses a Young&#39;s modulus of from about 4,000 MPa to about 10,000 MPa, or from about 6,000 MPA to about 8,000 MPa; and an onset decomposition temperature of from about 400° C. to about 600° C., or from about 450° C. to about 550° C. 
     Also described herein is a process of preparing a seamless polyimide belt for a fuser belt substrate via flow coating. In a centrifugal molding process, a thin fluorine or silicone release layer is applied on the inside of a rigid cylindrical mandrel, and then the polyimide layer is applied and subsequently cured and released it from the mandrel. Using a flow coating process eliminates the requirement of an extra release layer, thus reducing manufacturing cost. 
     The composition of the substrate layer comprises a polyamic acid such as a polyamic acid of pyromellitic dianhydride/4,4-oxydianiline and an internal release agent of a hydroxyl terminated polybutadiene, where the hydroxyl terminated polybutadiene chemically crosslinks together with the polyimide during the curing process. The internal release agent is present in an amount of from about 0.1 weight percent to about 10.0 weight percent or from about 0.3 weight percent to about 5.0 weight percent or from about 0.8 weight percent to about 2.0 weight percent. The hydroxyl terminated polybutadiene release agent is needed to fully release the polyimide layer from the stainless steel substrate. 
     The disclosed polyamic acid includes one of a polyamic acid of pyromellitic dianhydride/4,4′-oxydianiline, a polyamic acid of pyromellitic dianhydride/phenylenediamine, a polyamic acid of biphenyl tetracarboxylic dianhydride/4,4′-oxydianiline, a polyamic acid of biphenyl tetracarboxylic dianhydride/phenylenediamine, a polyamic acid of benzophenone tetracarboxylic dianhydride/4,4′-oxydianiline, a polyamic acid of benzophenone tetracarboxylic dianhydride/4,4′-oxydianiline/phenylenediamine, and the like and mixtures thereof. 
     The polyamic acid includes a polyamic acid of pyromellitic dianhydride/4,4-oxydianiline, commercially available from Industrial Summit Technology Corp., Parlin, N.J. with the trade name of PYRE-ML RC5019 (about 15-16 weight percent in N-methyl-2-pyrrolidone, NMP). Other commercial examples of polyamic acid of pyromellitic dianhydride/4,4-oxydianiline include, RC5057 (about 14.5-15.5 weight percent in NMP/aromatic hydrocarbon=80/20), and RC5083 (about 18-19 weight percent in NMP/DMAc=15/85), all from Industrial Summit Technology Corp., Parlin, N.J.; DURIMIDE® 100, commercially available from FUJIFILM Electronic Materials U.S.A., Inc. 
     The polyamic acid includes a polyamic acid of biphenyl tetracarboxylic dianhydride/4,4′-oxydianiline include U-VARNISH A, and S (about 20 weight in NMP); both from UBE America Inc., New York, N.Y. 
     The polyamic acid includes a polyamic acid of biphenyl tetracarboxylic dianhydride/phenylenediamine include PI-2610 (about 10.5 weight in NMP), and PI-2611 (about 13.5 weight in NMP), both from HD MicroSystems, Parlin, N.J. 
     The polyamic acid includes a polyamic acid of benzophenone tetracarboxylic dianhydride/4,4′-oxydianiline include RP46, and RP50 (about 18 weight percent in NMP), both from Unitech Corp., Hampton, Va. 
     The polyamic acid includes a polyamic acid of benzophenone tetracarboxylic dianhydride/4,4′-oxydianiline/phenylenediamine include PI-2525 (about 25 weight percent in NMP), PI-2574 (about 25 weight percent in NMP), PI-2555 (about 19 weight percent in NMP/aromatic hydrocarbon=80/20), and PI-2556 (about 15 weight percent in NMP/aromatic hydrocarbon/propylene glycol methyl ether=70/15/15), all from HD MicroSystems, Parlin, N.J. 
     Various amounts of polyamic acid can be selected for the substrate, such as for example, from about 90 weight percent to about 99.9 weight percent, from about 95 weight percent to about 99.7 weight percent, or from about 98 weight percent to about 99.2 weight percent. 
     Other polyamic acid or ester of polyamic acid examples that can be included in the substrate layer are from the reaction of a dianhydride and a diamine. Suitable dianhydrides include aromatic dianhydrides and aromatic tetracarboxylic acid dianhydrides such as, for example, 9,9-bis(trifluoromethyl)xanthene-2,3,6,7-tetracarboxylic acid dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 2,2-bis((3,4-dicarboxyphenoxy) phenyl)hexafluoropropane dianhydride, 4,4′-bis(3,4-dicarboxy-2,5,6-trifluorophenoxy)octafluorobiphenyl dianhydride, 3,3′,4,4′-tetracarboxybiphenyl dianhydride, 3,3′,4,4′-tetracarboxybenzophenone dianhydride, di-(4-(3,4-dicarboxyphenoxy)phenyl)ether dianhydride, di-(4-(3,4-dicarboxyphenoxy)phenyl) sulfide dianhydride, di-(3,4-dicarboxyphenyl)methane dianhydride, di-(3,4-dicarboxyphenyl)ether dianhydride, 1,2,4,5-tetracarboxybenzene dianhydride, 1,2,4-tricarboxybenzene dianhydride, butanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 2,2′,3,3′-biphenyltetracarboxylic dianhydride, 3,3′,4-4′-benzophenonetetracarboxylic dianhydride, 2,2′,3,3′-benzophenonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, bis(2,3-dicarboxyphenyl)sulfone 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexachloropropane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 4,4′-(p-phenylenedioxy) diphthalic dianhydride, 4,4′-(m-phenylenedioxy)diphthalic dianhydride, 4,4′-diphenylsulfidedioxybis(4-phthalic acid)dianhydride, 4,4′-diphenylsulfonedioxybis(4-phthalic acid)dianhydride, methylenebis(4-phenyleneoxy-4-phthalic acid)dianhydride, ethyl idenebis(4-phenyleneoxy-4-phthalic acid)dianhydride, isopropylidenebis-(4-phenyleneoxy-4-phthalic acid)dianhydride, hexafluoroisopropylidenebis(4-phenyleneoxy-4-phthalic acid)dianhydride, and the like. Exemplary diamines suitable for use in the preparation of the polyamic acid include 4,4′-bis-(m-aminophenoxy)-biphenyl, 4,4′-bis-(m-aminophenoxy)-diphenyl sulfide, 4,4′-bis-(m-aminophenoxy)-diphenyl sulfone, 4,4′-bis-(p-aminophenoxy)-benzophenone, 4,4′-bis-(p-aminophenoxy)-diphenyl sulfide, 4,4′-bis-(p-aminophenoxy)-diphenyl sulfone, 4,4′-diamino-azobenzene, 4,4′-diaminobiphenyl, 4,4′-diaminodiphenylsulfone, 4,4′-diamino-p-terphenyl, 1,3-bis-(gamma-aminopropyl)-tetramethyl-disiloxane, 1,6-diaminohexane, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 1,3-diaminobenzene, 4,4′-diaminodiphenyl ether, 2,4′-diaminodiphenylether, 3,3′-diaminodiphenylether, 3,4′-diaminodiphenylether, 1,4-diaminobenzene, 4,4′-diamino-2,2′,3,3′,5,5′,6,6′-octafluoro-biphenyl, 4,4′-diamino-2,2′,3,3′,5,5′,6,6′-octafluorodiphenyl ether, bis[4-(3-aminophenoxy)-phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ketone, 4,4′-bis(3-aminophenoxy)biphenyl, 2,2-bis[4-(3-aminophenoxy)phenyl]-propane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenylmethane, 1,1-di(p-aminophenyl)ethane, 2,2-di(p-aminophenyl)propane, and 2,2-di(p-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, and the like and mixtures thereof. 
     The dianhydrides and diamines are, for example, selected in a weight ratio of dianhydride to diamine of from about 20:80 to about 80:20, and more specifically, in an about 50:50 weight ratio. The above aromatic dianhydride like aromatic tetracarboxylic acid dianhydrides and diamines like aromatic diamines are used singly or as a mixture, respectively. 
     The hydroxyl terminated polybutadiene (HTPB) possesses a weight average molecular weight of from about 200 to about 10,000, or from about 500 to about 5,000, present in an amount of from about 0.1 weight percent to about 10 weight percent or from about 0.3 weight percent to about 5.0 weight percent or from about 0.8 weight percent to about 2.0 weight percent of the substrate layer. 
     The polybutadiene (PB) backbone of the HTPB can be poly(1,3-butadiene), poly(1,4-butadiene), hydrogenated poly(1,3-butadiene), hydrogenated poly(1,4-butadiene), and mixtures thereof. 
     Examples of the HTPB that can be used in the substrate layer include KRASOL® HLBH-P2000 (hydroxyl hydrogenated PB), HLBH-P3000 (hydroxyl hydrogenated PB), LBH-P2000 (hydroxyl value of 50 mg KOH/g; M n =2,100), LBH-P3000 (hydroxyl value of 37 mg KOH/g; M n =3,000), LBH-P5000, LBH 2000 (hydroxyl value of 52 mg KOH/g; M n =2,100), LBH 3000 (hydroxyl value of 37 mg KOH/g; M n =3,000), LBH 5000 (hydroxyl value of 22 mg KOH/g; M n =5,000), LBH 10000, LBH 2040 (mercaptoethanol PB), POLY BD® R45HT, R45M, R45HTLO (hydroxyl functionality of 2.4-2.6; M n =2,800; T g =−75° C.), LFM, R20LM, and R30LM, all commercially available from Sartomer Company, Warrington, Pa. 
     The polyimide substrate composition can optionally contain a polysiloxane copolymer to enhance or smooth the coating. The concentration of the polysiloxane copolymer is less than about 1 weight percent or less than about 0.2 weight percent. The optional polysiloxane copolymer includes a polyester modified polydimethylsiloxane, commercially available from BYK Chemical with the trade name of BYK® 310 (about 25 weight percent in xylene) and 370 (about 25 weight percent in xylene/alkylbenzenes/cyclohexanone/monophenylglycol=75/11/7/7); a polyether modified polydimethylsiloxane, commercially available from BYK Chemical with the trade name of BYK® 330 (about 51 weight percent in methoxypropylacetate) and 344 (about 52.3 weight percent in xylene/isobutanol=80/20), BYK®-SILCLEAN 3710 and 3720 (about 25 weight percent in methoxypropanol); a polyacrylate modified polydimethylsiloxane, commercially available from BYK Chemical with the trade name of BYK®-SILCLEAN 3700 (about 25 weight percent in methoxypropylacetate); or a polyester polyether modified polydimethylsiloxane, commercially available from BYK Chemical with the trade name of BYK® 375 (about 25 weight percent in Di-propylene glycol monomethyl ether). The polyimide, the hydroxyl terminated polybutadiene and the polysiloxane polymer of the substrate are present in a weight ratio of about 99.89/0.1/0.01 to about 94/5/1. 
     Typical reactions between the polyamic acid and the hydroxyl terminated polybutadiene can be represented by the following three steps: 
     Step 1: Immobilization of HTPB as Cross-linking and/or Grafting by the Reaction of PAA and HTPB 
     
       
         
         
             
             
         
       
     
     Step 2: Further Cross-linking in Solid Phase and Effective Imidization 
     
       
         
         
             
             
         
       
     
     Step 3: Cyclization of PB, Cleavage of Ester Linkage, Decarbonylation, And Effective Imididization of Residual PAA 
     
       
         
         
             
             
         
       
         
         
           
             The chemistry of R is given below: 
           
         
       
    
     
       
         
         
             
             
         
       
     
     The hydroxyl terminated polybutadiene not only is chemically attached to the polyimide network, but also cyclizes above 300° C., thereby bringing extra strength to the resulting polyimide fuser belt. 
     The polyimide-HTPB composition is flow coated on a welded stainless steel belt at the desired product circumference. The polyimide-HTPB belt is partially cured, or pre-cured, and self releases from the stainless steel belt, and then is further completely cured at about 250° C. to about 370° C., or from about 300° C. to about 340° C., for a time of about 30 minutes to about 150 minutes, or from about 60 minutes to about 120 minutes under tension in the configuration shown in  FIG. 4 . This final curing is at a tension of from about 1 kilogram to about 10 kilograms. As shown in  FIG. 4 , the pre-cured belt  210  is tensioned between two rollers  250  while rotating the direction of arrow  20 . The final curing produces a belt that exhibits a modulus suitable for use as a fuser member. 
     The seam thickness and profile can be minimized, and the surface finish and roughness of the substrate belt can be specified, for example, a rough lathed or honed belt is better for the polyimide layer release. Such a configuration easily allows the production of belts of various lengths and widths. Using a rotating mandrel limits the width and length of the belts able to be produced as each belt requires a separate mandrel. 
     In one embodiment, the coating belt substrate is a rough lathed belt substrate with a R a  of from about 0.01 micron to about 0.5 micron, or from about 0.05 micron to about 0.3 micron, or from about 0.1 micron to about 0.2 micron; and a R max  or from about 0.05 micron to about 2 micron, or from about 0.1 micron to about 1 micron, or from about 0.2 micron to about 0.7 micron. The back of the polyimide fuser substrate flow coated from this substrate is similarly rough lathed, thus recognizable. 
     In another embodiment, the coating belt substrate is a honed belt substrate with a R a  of from about 0.15 micron to about 1 micron, or from about 0.2 micron to about 0.8 micron, or from about 0.3 micron to about 0.7 micron; and a R max  of from about 0.5 micron to about 10 microns, or from about 1 micron to about 7 microns, or from about 2 microns to about 4 microns. The back of the polyimide fuser substrate flow coated from this substrate is similarly honed, thus recognizable. 
     The polyimide-HTPB layer thickness can be achieved by single pass or multi pass coating. For single pass, the polyimide layer is coated, and pre-cured at a temperature between about 125° C. and about 190° C. for a time of about 30 to about 90 minutes, and then fully cured at a temperature between about 250° C. and about 370° C. for a time of about 30 to about 90 minutes. For multi-pass, such as dual pass, the bottom polyimide layer is coated on a substrate and pre-cured between about 125° C. and about 190° C. for a time of about 30 to about 90 minutes, and the top polyimide layer is subsequently coated and pre-cured between about 125° C. and about 190° C. for a time of about 30 to about 90 minutes, and then the dual layer polyimide layer is fully cured at a temperature between about 250° C. and about 370° C. for a time of about 30 to about 90 minutes. In an embodiment a stainless steel belt is used as the coating substrate. The substrate is rotated at a speed of from about 20 rpm to about 100 rpm, or from about 40 rpm to about 60 rpm during the thermal curing of the coating. 
     The polyimide substrate composition includes a solvent. Examples of the solvent selected to form the composition include toluene, hexane, cycloheaxne, heptane, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, N,N′-dimethylformamide, N,N′-dimethylacetamide, N-methylpyrrolidone (NMP), methylene chloride and the like and mixtures thereof where the solvent is selected, for example, in an amount of from about 70 weight percent to about 95 weight percent, and from 80 weight percent to about 90 weight percent based on the amounts in the coating mixture. 
     Additives and additional conductive or non-conductive fillers may be present in the above-described composition or the various layers of the fuser belt. In various embodiments, other filler materials or additives including, for example, inorganic particles, can be used for the coating composition and the subsequently formed surface layer. Conductive fillers used herein include carbon blacks such as carbon black, graphite, fullerene, acetylene black, fluorinated carbon black, and the like; carbon nanotubes, metal oxides and doped metal oxides, such as tin oxide, antimony dioxide, antimony-doped tin oxide, titanium dioxide, indium oxide, zinc oxide, indium oxide, indium-doped tin trioxide, and the like; and mixtures thereof. Certain polymers such as polyanilines, polythiophenes, polyacetylene, poly(p-phenylene vinylene), poly(p-phenylene sulfide), pyrroles, polyindole, polypyrene, polycarbazole, polyazulene, polyazepine, poly(fluorine), polynaphthalene, salts of organic sulfonic acid, esters of phosphoric acid, esters of fatty acids, ammonium or phosphonium salts and mixture thereof can be used as conductive fillers. In various embodiments, other additives known to one of ordinary skill in the art can also be included to form the disclosed composite materials. 
     The composition is coated on a substrate in any suitable known manner. Typical techniques for coating such materials on the substrate layer include flow coating, liquid spray coating, dip coating, wire wound rod coating, fluidized bed coating, powder coating, electrostatic, spraying, sonic spraying, blade coating, molding, laminating, and the like. 
     Specific embodiments will now be described in detail. These examples are intended to be illustrative, and not limited to the materials, conditions, or process parameters set forth in these embodiments. All parts are percentages by solid weight unless otherwise indicated. 
     EXAMPLES 
     Experimentally, a composition comprising polyamic acid of pyromellitic dianhydride/4,4-oxydianiline/hydroxyl terminated polybutadiene=99/1 was prepared in NMP, about 13 wt % solid, where the polyamic acid was Pyre-M.L. RC5019, and the hydroxyl terminated polybutadiene was POLY BD® R45HTLO. The clear coating solution was flow coated on a stainless steel belt, and subsequently cured at 125° C. for 30 minutes, and 190° C. for 30 minutes. A 40 μm thick polyimide bottom layer was formed on the substrate belt. Subsequently, a 2 nd  pass polyimide layer was coated on top of the bottom polyimide layer, and cured at 125° C. for 30 minutes and then at 190° C. for 30 minutes. The dual pass coating produced an 80 μm polyimide belt. 
     The pre-cured polyimide belt self released from the substrate belt, and was further cured at 320° C. for an additional hour under tension. A seamless polyimide belt was obtained with a smooth surface and a thickness of about 80 μm. 
     The polyimide belt was further tested for modulus and onset decomposition temperature. The modulus was greater than about 7,200 MPa, and the onset decomposition temperature was greater than about 550° C. As a comparison, commercially available polyimide belts possess a modulus of from about 6000 MPa to about 8,000 MPa. The onset decomposition temperature of commercially available polyimide belts is about 500° C. Thus, the key properties of the disclosed polyimide belt were comparable to commercially available belts. 
     It will be appreciated that variants of the above-disclosed and other features and functions or alternatives thereof may be combined into other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art, which are also encompassed by the following claims.