Patents by Inventor Pranab Bagchi

Pranab Bagchi 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: 5066572
    Abstract: This invention describes a substantially less pressure sensitive photographic film comprising a support, at least one light sensitive silver halide element, and an overlaying element comprising gelatin-grafted or case-hardened gelatin-grafted soft polymer particle composite element. The incorporation of such an overlaying composite particle cushioning layer does not compromise either the physical properties or physical integrity of the film unit. This invention is particularly suitable for highly pressure sensitive tabular grain emulsions.
    Type: Grant
    Filed: March 22, 1990
    Date of Patent: November 19, 1991
    Assignee: Eastman Kodak Company
    Inventors: Kevin M. O'Connor, Richard P. Szajewski, Pranab Bagchi
  • Patent number: 5055379
    Abstract: A negative-working photoresist composition comprising, in admixture, (a) dye-loaded or dye-precursor-loaded polymeric particles individually covered with a layer of gelatin that is covalently bonded thereto and (b) a radiation-sensitive dichromate is useful in the preparation of continuous tone dyed imaging elements such as color filter arrays for use in solid state color image sensing devices.
    Type: Grant
    Filed: March 19, 1990
    Date of Patent: October 8, 1991
    Assignee: Eastman Kodak Company
    Inventors: Pranab Bagchi, Raymond F. Reithel, Tsang J. Chen, Steven Evans
  • Patent number: 5026632
    Abstract: It has been shown by Photon Correlation Spectroscopy that when additional hardener is added to below saturation gel-grafted polymer particles, the gel layer shrinks due to hardening, as there is no free gel left in solution. In films, such case-hardened gelatin-grafted soft polymer particles can act as highly elastic stress absorbing fillers. This is because the dry case-hardened shell is expected to form a thin hard shell around the soft polymer particles. It is shown that gelatin-grafted soft polymer particles and case-hardened gelatin-grafted soft polymer particles, incorporated in the emulsion layers of pressure sensitive photographic products, produce coatings with highly reduced pressure sensitivity without any developability or delamination concerns. In this invention the case-hardened gelatin-grafted polymer particles are preferred over the simple gelatin-grafted material.
    Type: Grant
    Filed: March 22, 1990
    Date of Patent: June 25, 1991
    Assignee: Eastman Kodak Company
    Inventors: Pranab Bagchi, William L. Gardner
  • Patent number: 5013640
    Abstract: The invention is generally accomplished by utilization of a surfactant for very small particle photographic dispersions. Three types of such surfactants that have been identified are as follows:Type A--Surfactant comprising 6 to 22 carbon atom hydrophobic tail with one or more attached hydrophilic chains comprising at least 8 oxyethylene and/or glycedyl ether groups that may or may not be terminated with a negative charge such as a sulfate group.Type B--Block oligomeric surfactants comprising hydrophobic polyoxypropylene blocks (A) and hydrophilic polyoxyethylene blocks (B) joined in the manner of A-B-A, B-A-B, A-B, (A-B).sub.n .tbd.G.tbd.(B-A), or (B-A).sub.n .tbd.G.tbd.(A-B).sub.n, where G is a connective organic moiety and n is between 1 and 3.Type C--Sugar surfactants, comprising between one to three 6 to 22 carbon atom hydrophobic tail with one or more attached hydrophilic mono or oligosaccharidic chains that may or may not be terminated by a negatively charged group such as a sulfate group.
    Type: Grant
    Filed: June 15, 1989
    Date of Patent: May 7, 1991
    Assignee: Eastman Kodak Company
    Inventors: Pranab Bagchi, Gary J. McSweeney, Steven J. Sargeant
  • Patent number: 4990431
    Abstract: The invention is performed by providing a first flow of water and surfactant, a second flow comprising solvent, base and photographic material, and mixing said first and second streams and either simultaneously or immediately following thereof neutralizing said streams to prevent hydrolysis of a hydrolyzable surfactant and/or premature precipitation of particles before neutralization. The streams then may be immediately treated for formation into photographic materials. In a preferred method the first and second stream may be brought together immediately prior to a mixer with addition of acid directly into the mixer to neutralize the dispersion of fine particles.
    Type: Grant
    Filed: January 17, 1989
    Date of Patent: February 5, 1991
    Assignee: Eastman Kodak Company
    Inventors: Pranab Bagchi, James T. Beck, Lia A. Crede
  • Patent number: 4970139
    Abstract: Base and auxiliary solvent solubilized precipitated dispersions of couplers and other photographic materials usually produce very small particle dispersions, and usually such dispersions are extremely highly reactive because of the smallness of the particle size. However, some relatively more hydrophobic couplers, even though they produce small particles when a dispersion is formed by the precipitation technique, lead to extremely unreactive dispersions. The method of this invention constitutes a single step precipitation technique where a permanent high boiling water insoluble coupler solvent is incorporated into the precipitated particles to produce photographically highly active coupler dispersions.
    Type: Grant
    Filed: October 2, 1989
    Date of Patent: November 13, 1990
    Assignee: Eastman Kodak Company
    Inventor: Pranab Bagchi
  • Patent number: 4933270
    Abstract: The invention provides a method of forming a dispersion of base degradable hydrophobic component for a photographic system. The invention is accomplished by mixing the component, solvent, and surfactant, at an elevated temperature if necessary, metering the mixture of solvent, surfactant, and hydrophobic component to an excess of water with agitation so as to precipitate from the water solvent solution small particles of the hydrophobic component. The small particles then form a stable dispersion, after washing by dialysis or diafiltration, that will not agglomerate during storage prior to use. The preferred photographic component for use in the system of the invention is an ester terminated photographic coupler that would decompose if subjected to the high pH treatment of prior art procedures.
    Type: Grant
    Filed: September 26, 1988
    Date of Patent: June 12, 1990
    Assignee: Eastman Kodak Company
    Inventor: Pranab Bagchi
  • Patent number: 4920004
    Abstract: There are disclosed polymer particles that are individually covered with gelatin that is covalently bonded thereto. The particles are useful in a variety of applications, such as photographic matting agents.
    Type: Grant
    Filed: February 7, 1989
    Date of Patent: April 24, 1990
    Assignee: Eastman Kodak Company
    Inventor: Pranab Bagchi
  • Patent number: 4855219
    Abstract: A photographic element comprising a support having thereon a gelatin-containing layer, and a matting agent comprising polymer particles covalently bonded to the gelatin in the layer. The polymer particles may be individually covered with gelatin that is covalently bonded thereto and the gelatin that is covalently bonded to the particles may be cross-linked with the gelatin in the layer. There is also provided a process of preparing a photographic element comprising a matting agent and a layer comprising gelatin. In this process, the gelatin layer is coated onto a support, at least partially dried, and polymer particles are applied to the layer. The polymer particles are then covalently bonded to the gelatin in the layer.
    Type: Grant
    Filed: September 18, 1987
    Date of Patent: August 8, 1989
    Assignee: Eastman Kodak Company
    Inventors: Pranab Bagchi, Melvin D. Sterman, Howard M. Low