Patents by Inventor Thomas R. Hoffend

Thomas R. Hoffend has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4490455
    Abstract: This invention is generally directed to an electrostatic toner composition comprised of resin particles, pigment particles, and from about 0.25 weight percent to about 20 weight percent based on the weight of the toner particles of an amine acid salt charge enhancing additive composition of the following formula: ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 are independently selected from the group consisting of alkyl groups, and aromatic groups, and A is an anion.
    Type: Grant
    Filed: December 20, 1982
    Date of Patent: December 25, 1984
    Assignee: Xerox Corporation
    Inventors: Thomas R. Hoffend, Michelle M. Bruzee
  • Patent number: 4397935
    Abstract: The present invention is directed to a developer composition comprised of resin particles, pigment particles, carrier particles, and a charge enhancing additive of the following formula ##STR1## wherein R is an alkyl radical containing from about 1 carbon atom to about 25 carbon atoms, A is an anion, and x, y and z are numbers representing the weight percent of monomer present, wherein z is equal to about 1 weight percent to about 50 weight percent, and the sum of x plus y is equal to 100 minus z, thus this sum is equal to about 50 weight percent to about 99 weight percent, accordingly, the total sum of x+y+z is equal to about 100 weight percent; which compositions are useful in causing the development of electrostatic latent images in electrostatographic imaging systems wherein the photoresponsive device utilized is charged negatively.
    Type: Grant
    Filed: January 18, 1982
    Date of Patent: August 9, 1983
    Assignee: Xerox Corporation
    Inventors: Roger N. Ciccarelli, Thomas R. Hoffend
  • Patent number: 4330460
    Abstract: Dispersion polymerization process for producing colored toner particles comprising admixing a colorant with a monomer to form an oil soluble organic phase, admixing a polymerization initiator with the organic phase, admixing the organic phase with an aqueous phase containing a suspending agent and an inorganic salt therein under polymerization conditions to form a suspension, polymerizing the suspension under continuous agitation to provide polymer particles containing the colorant and having a particle size in the range of from about 1 micron to about 100 microns, and recovering the polymer particles. The inorganic salt inhibits polymerization in the aqueous phase. Developer compositions and processes for developing electrostatic latent images are also disclosed.
    Type: Grant
    Filed: April 14, 1980
    Date of Patent: May 18, 1982
    Assignee: Xerox Corporation
    Inventors: Thomas R. Hoffend, Robert A. Nelson
  • Patent number: 4314931
    Abstract: This invention relates to a process for substantially eliminating polymerization inhibition in a pigment containing dispersion polymerization reaction, which comprises grafting polymer molecules onto the pigment used in the polymerization reaction, whereby there results a polymerized product which contains essentially no monomer material.
    Type: Grant
    Filed: June 9, 1980
    Date of Patent: February 9, 1982
    Assignee: Xerox Corporation
    Inventors: Thomas R. Hoffend, Moshe Levy
  • Patent number: 4185140
    Abstract: Polymeric release agents having functional groups such as carboxy, hydroxy, epoxy, amino, isocyanate, thioether or mercapto groups are applied to a heated fuser member in an electrostatic reproducing apparatus to form thereon a thermally stable, renewable, self-cleaning layer having excellent toner release properties for conventional electroscopic thermoplastic resin toners. The functional polymeric fluids interact with the fuser member in such a manner as to form a thin, thermally stable interfacial barrier at the surface of the fuser member while leaving an outer film or layer of unreacted release fluid. The interfacial barrier is strongly attached to the fuser member surface and prevents electroscopic thermoplastic resin toner material from contacting the outer surface of the fuser member. The material on the surface of the fuser member is of minimal thickness and thereby represents a minimal thermal barrier.
    Type: Grant
    Filed: April 19, 1978
    Date of Patent: January 22, 1980
    Assignee: Xerox Corporation
    Inventors: Stephen Strella, Donald A. Seanor, George R. Imperial, Thomas R. Hoffend
  • Patent number: 4170957
    Abstract: Polyarylsiloxanes are used on metal fusing devices in photocopiers to fix particulate thermoplastic toner to a substrate while the toner is in a fused state. The polyarylsiloxanes can be continuously applied in minimal thicknesses on the fusing device to form a thermally stable, renewable, self-cleaning layer having excellent toner release properties. A preferred polyarylsiloxane is polyphenylmethyl dimethyl siloxane.
    Type: Grant
    Filed: August 29, 1977
    Date of Patent: October 16, 1979
    Assignee: Xerox Corporation
    Inventors: Clifford O. Eddy, Thomas R. Hoffend
  • Patent number: 4101686
    Abstract: Polymeric release agents having functional groups such as carboxy, hydroxy, epoxy, amino, isocyanate, thioether or mercapto groups are applied to a heated fuser member in an electrostatic reproducing apparatus to form thereon a thermally stable, renewable, self-cleaning layer having excellent toner release properties for conventional electroscopic thermoplastic resin toners. The functional polymeric fluids interact with the fuser member in such a manner as to form a thin, thermally stable interfacial barrier at the surface of the fuser member while leaving an outer film or layer of unreacted release fluid. The interfacial barrier is strongly attached to the fuser member surface and prevents electroscopic thermoplastic resin toner material from contacting the outer surface of the fuser member. The material on the surface of the fuser member is of minimal thickness and thereby represents a minimal thermal barrier.
    Type: Grant
    Filed: July 24, 1974
    Date of Patent: July 18, 1978
    Assignee: Xerox Corporation
    Inventors: Stephen Strella, Donald A. Seanor, George R. Imperial, Thomas R. Hoffend
  • Patent number: 4065586
    Abstract: Polyarylsiloxanes are used on fusing devices in photocopiers to fix particulate thermoplastic toner to a substrate while the toner is in a fused state. The polyarylsiloxanes can be continuously applied in minimal thicknesses on the fusing device to form a thermally stable, renewable, self-cleaning layer having excellent toner release properties. A preferred polyarylsiloxane is polyphenylmethyl dimethyl siloxane.
    Type: Grant
    Filed: March 1, 1976
    Date of Patent: December 27, 1977
    Assignee: Xerox Corporation
    Inventors: Clifford O. Eddy, Thomas R. Hoffend