Patents by Inventor Dhan N. Parekh

Dhan N. Parekh 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: 4863764
    Abstract: A method for achieving the flame retardancy of polypropylene fiber and for fabrics which include such fibers has been devised which has a low add-on finish. The finish comprises a mixture containing a bromochlorinated paraffin having a high concentration of bromine, up to 80% by weight, but, notwithstanding low add-on, the invention will produce an extremely effective fire retardancy where the bromine and chlorine constituents equal 20% and 40% respecively by weight of the bromochlorinated paraffin. Antimony oxide, preferably a antimony pentoxide is used, having a preferred particulate size in the range of 30-50 millimicrons. The quantity of antimony oxide to be used may be 1/3 mole to 1 mole of bromine. After the bromochlorinated paraffin is combined with emulsifiers to form a stable premix, the premix and antimony pentoxide are preferably combined with a binder consisting of an ethylacrylate latex.
    Type: Grant
    Filed: May 31, 1988
    Date of Patent: September 5, 1989
    Assignee: West Point Pepperell, Inc.
    Inventors: Gayron N. Davis, Henry W. Haynes, Sr., Dhan N. Parekh
  • Patent number: 4589233
    Abstract: A sectional cloth backed abrasive belt comprising a series of abrasive coated cloth backed sections joined together so that the joints between sections are at an angle of from about 45.degree., to about 85.degree. to the running direction of the belt. The cloth backing has at least a portion of the fill filaments of the cloth backing at an angle of from 45.degree. to 85.degree. to the warp filaments of the cloth backing and the sections are joined such that at least 30% of the fill filaments are disposed in the running direction of the belt. The invention further comprises the process for making such an abrasive belt by joining appropriate parallelogram shaped sections. The section of abrasive belt of the invention has increased strength in the running direction of the belt and decreased stretch in the running direction of the belt.
    Type: Grant
    Filed: June 25, 1984
    Date of Patent: May 20, 1986
    Assignee: Carborundum Abrasives Company
    Inventors: Dhan N. Parekh, David E. Williams
  • Patent number: 4543106
    Abstract: A coated abrasive product which comprises a fabric backing, a layer of abrasive grain and at least one layer of resin between the backing and abrasive grain. Hollow microspheres are present and at least partly and usually entirely embedded in the resin layer. In general, such hollow microspheres comprise hollow spherical bodies which may be of glass or plastic materials such as a phenolic resin, which have a diameter of from about 5 to about 500 microns and an average diameter of from about 25 to about 150 microns. Such hollow microspheres generally have a shell thickness which averages from about 5 to about 20 percent of the diameter of the microsphere. Such microspheres are usually incorporated into the resin layer in an amount of from about 5 to about 20 percent by weight of the resin layer.
    Type: Grant
    Filed: June 25, 1984
    Date of Patent: September 24, 1985
    Assignee: Carborundum Abrasives Company
    Inventor: Dhan N. Parekh
  • Patent number: 4478610
    Abstract: A flexible sheet material particularly suitable as a backing for coated abrasive products and method of making same are described. The flexible sheet material is of that type employing a straight warp fabric. The yarns of the straight warp fabric are coated and at least partially impregnated with a flexible polymeric material, such as polyvinyl alcohol, having thereover an intermediate filling coat of a phenol formaldehyde resin/latex and an outer filling coat of phenol formaldehyde resin. Alternatively, the straight warp fabric includes a penetrating base coating of flexible polymeric material and thereover a backfilling including approximately equal parts by weight of calcium carbonate and magnesium carbonate dispersed in a flexible synthetic polymeric resin which backfilling fills the interstices and encapsulates the yarns of one of the yarn arrays that form the straight warp fabric. The straight warp fabric may include a non-woven web located between adjacent arrays of warp and weft yarns.
    Type: Grant
    Filed: February 6, 1984
    Date of Patent: October 23, 1984
    Assignee: Carborundum Abrasives Company
    Inventors: Dhan N. Parekh, Paul R. Schweyen
  • Patent number: 4437865
    Abstract: A flexible sheet material particularly suitable as a backing for coated abrasive products and method of making same are described. The flexible sheet material is of that type employing a straight warp fabric. The yarns of the straight warp fabric are coated and at least partially impregnated with a flexible polymeric material, such as polyvinyl alcohol, having thereover an intermediate filling coat of a phenol formaldehyde resin/latex and an outer filling coat of phenol formaldehyde resin. Alternatively, the straight warp fabric includes a penetrating base coating of flexible polymeric material and thereover a backfilling including approximately equal parts by weight of calcium carbonate and magnesium carbonate dispersed in a flexible synthetic polymeric resin which backfilling fills the interstices and encapsulates the yarns of one of the yarn arrays that form the straight warp fabric. The straight warp fabric may include a non-woven web located between adjacent arrays of warp and weft yarns.
    Type: Grant
    Filed: August 27, 1982
    Date of Patent: March 20, 1984
    Assignee: Carborundum Abrasive Company
    Inventors: Dhan N. Parekh, Paul R. Schweyen