Patents by Inventor Subhotosh Khan

Subhotosh Khan 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: 8206808
    Abstract: A prepreg composite material that includes a fiber layer and a resin comprising a thermoset resin component, a curing agent and a fibrous micropulp. The micropulp component is an aramid fiber having a volume average length of from 0.01 to 100 micrometers. The prepreg is useful in composite panel construction for minimizing fluid permeation into the cured structure. This prepreg is particularly suitable for making honeycomb sandwich panels. Film adhesives, liquid and paste resins containing aramid fiber micropulp are also disclosed.
    Type: Grant
    Filed: June 2, 2011
    Date of Patent: June 26, 2012
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Subhotosh Khan, Halvar Young Loken
  • Publication number: 20110274873
    Abstract: A prepreg composite material that includes a fiber layer and a resin comprising a thermoset resin component, a curing agent and a fibrous micropulp. The micropulp component is an aramid fiber having a volume average length of from 0.01 to 100 micrometers. The prepreg is useful in composite panel construction for minimizing fluid permeation into the cured structure. This prepreg is particularly suitable for making honeycomb sandwich panels. Film adhesives, liquid and paste resins containing aramid fiber micropulp are also disclosed.
    Type: Application
    Filed: June 2, 2011
    Publication date: November 10, 2011
    Applicant: E. I. DU PONT DE NEMOURS AND COMPANY
    Inventors: SUBHOTOSH KHAN, HALVAR YOUNG LOKEN
  • Patent number: 8025949
    Abstract: This invention relates to a honeycomb having cells of paper, comprising by weight 3 to 30 parts by weight aliphatic polyamide binder, and 70 to 97 parts of a poly(paraphenylene terephthalamide) fiber having a modulus of 600 grams per denier (550 grams per dtex) or greater, based on the aliphatic polyamide binder and PPD-T fiber in the paper. In another embodiment, the honeycomb is made from paper comprising by weight 30 to 50 parts aliphatic polyamide binder, and 50 to 70 parts of a poly(paraphenylene terephthalamide) fiber having a modulus of 600 grams per denier (550 grams per dtex) or greater, based on the aliphatic polyamide binder and PPD-T fiber in the paper. Both papers have an average specific tensile index of 60 (lbs/in)/opsy (310 Nm/g) or greater. Articles made from the honeycombs include a panel or an aerodynamic structure.
    Type: Grant
    Filed: December 15, 2006
    Date of Patent: September 27, 2011
    Assignee: E.I. du Pont de Nemours and Company
    Inventors: Mikhail R. Levit, Subhotosh Khan, Gary Lee Hendren
  • Patent number: 7927691
    Abstract: A prepreg composite material that includes a fiber layer and a resin comprising a thermoset resin component, a curing agent and a fibrous micropulp. The micropulp component is an aramid fiber having a volume average length of from 0.01 to 100 micrometers. The prepreg is useful in composite panel construction for minimizing fluid permeation into the cured structure. This prepreg is particularly suitable for making honeycomb sandwich panels. Film adhesives, liquid and paste resins containing aramid fiber micropulp are also disclosed.
    Type: Grant
    Filed: April 3, 2009
    Date of Patent: April 19, 2011
    Assignee: E.I. du Pont de Nemours and Company
    Inventors: Subhotosh Khan, Halvar Young Loken
  • Patent number: 7815993
    Abstract: This invention relates to an improved flame retardant honeycomb comprising high modulus fiber and a flame retardant thermoplastic binder having a melt point of from 120° C. to 350° C. and a limiting oxygen index of 26 or greater, methods for making the honeycomb, and articles comprising the honeycomb. In a preferred embodiment the paper in the honeycomb has a flame classification of UL-94 V-0.
    Type: Grant
    Filed: December 15, 2006
    Date of Patent: October 19, 2010
    Assignee: E.I. du Pont de Nemours and Company
    Inventors: Gary Lee Hendren, Subhotosh Khan, Mikhail R. Levit
  • Patent number: 7785520
    Abstract: A honeycomb containing a thermoplastic material, high modulus fiber and thermoset resin has process steps of fracturing the thermoset resin, bending, molding or forming the honeycomb in a mold or over a form, heating to allow flow of thermoplastic material and cooling of the honeycomb to retain the shape of the mold or form.
    Type: Grant
    Filed: December 15, 2006
    Date of Patent: August 31, 2010
    Assignee: E.I. du Pont de Nemours and Company
    Inventors: Subhotosh Khan, Gary Lee Hendren, Mikhail R. Levit
  • Patent number: 7771809
    Abstract: This invention relates to a honeycomb comprising cells having edges forming a face of the honeycomb, the face defined by a plurality of points and having an area of curvature wherein at least two of the points are located in different tangential planes, the walls of the cells comprising 5 to 50 parts by weight thermoplastic material having a melting point of from 120° C. to 350° C., and 50 to 95 parts by weight of a high modulus fiber having a modulus of 600 grams per denier (550 grams per dtex) or greater, based on the total amount of thermoplastic material and high modulus fiber in the walls; wherein less than 25 percent of the honeycomb cells in the area of curvature have a re-entrant angle of greater than 180 degrees. This invention also relates to articles including panels and/or aerodynamic structures comprising the honeycomb.
    Type: Grant
    Filed: December 15, 2006
    Date of Patent: August 10, 2010
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Gary Lee Hendren, Mikhail R. Levit, Subhotosh Khan
  • Patent number: 7771811
    Abstract: This invention relates to an improved high performance honeycomb, methods for making the same, and articles including aerodynamic structures comprising the honeycomb, the honeycomb made with a paper that allows rapid impregnation of the honeycomb by structural resins while retarding excessive impregnation of node-line adhesives during manufacture. The honeycomb comprises a paper having a thickness of from 25 to 75 microns and a Gurley porosity of 2 seconds or greater and comprising high modulus fiber and thermoplastic binder having a melt point of from 180° C. to 300° C., wherein at least 30 percent by weight of the total amount of thermoplastic material is in the form of discrete film-like particles in the paper, the particles having a film thickness of about 0.1 to 5 micrometers and a minimum dimension perpendicular to that thickness of at least 30 micrometers.
    Type: Grant
    Filed: December 15, 2006
    Date of Patent: August 10, 2010
    Assignee: E.I. du Pont de Nemours and Company
    Inventors: Mikhail R. Levit, Subhotosh Khan, Gary Lee Hendren
  • Patent number: 7771810
    Abstract: This invention relates to a honeycomb including articles such as a panel or aerodynamic structure comprising matrix resin and paper, the paper comprising 50 to 80 parts by weight fibrous material having a modulus of 600 grams per denier (550 grams per dtex) or greater, 0 to 50 parts by weight powdered inorganic material, and 20 parts by weight or greater thermoplastic fiber, the improvement comprising the thermoplastic fiber is a binder for the paper and has a melting temperature above the curing temperature of the matrix resin; a glass transition temperature of greater than 100° C., and the weight average molecular weight of the thermoplastic polymer in the thermoplastic fibers changes 20% or less after being maintained for 10 minutes at the melting temperature.
    Type: Grant
    Filed: December 15, 2006
    Date of Patent: August 10, 2010
    Assignee: E.I. du Pont de Nemours and Company
    Inventors: Mikhail R. Levit, Subhotosh Khan, Gary Lee Hendren
  • Publication number: 20090252920
    Abstract: A prepreg composite material that includes a fiber layer and a resin comprising a thermoset resin component, a curing agent and a fibrous micropulp. The micropulp component is an aramid fiber having a volume average length of from 0.01 to 100 micrometers. The prepreg is useful in composite panel construction for minimizing fluid permeation into the cured structure. This prepreg is particularly suitable for making honeycomb sandwich panels. Film adhesives, liquid and paste resins containing aramid fiber micropulp are also disclosed.
    Type: Application
    Filed: April 3, 2009
    Publication date: October 8, 2009
    Applicant: E.I. DU PONT DE NEMOURS AND COMPANY
    Inventors: Subhotosh Khan, Halvar Young Loken
  • Publication number: 20090214818
    Abstract: This invention relates to a honeycomb core having improved shear properties made from a p-aramid paper substrate. The paper comprises 50-85 parts by weight of p-aramid floc, 10-40 parts by weight of p-aramid pulp and 5-30 parts by weight of aramid fibrids. Prior to impregnation with resin, the paper has a Gurley air resistance of from 3 to 40 seconds per 100 milliliters.
    Type: Application
    Filed: February 20, 2009
    Publication date: August 27, 2009
    Inventors: Mikhail R. Levit, Subhotosh Khan
  • Patent number: 7459044
    Abstract: A sheet comprising thermoplastic polymer (TP) and short high tensile modulus fibers, in which the concentration of TP in the middle of the sheet is higher than at the surface of the sheet, useful for making prepregs with a thermoset resin.
    Type: Grant
    Filed: February 3, 2005
    Date of Patent: December 2, 2008
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Subhotosh Khan, Michael Robert Samuels, Mikhail R. Levit
  • Publication number: 20080286522
    Abstract: This invention relates to a honeycomb and articles made therefrom, the articles having cell walls provided with a structural or matrix resin, the planes of the cell walls being parallel to the Z-dimension of the honeycomb, the honeycomb cell walls comprising 5 to 35 parts by weight thermoplastic material having a melting point of from 120° C. to 350° C. and a coefficient of thermal expansion of 180 ppm/° C. or less; and 65 to 95 parts by weight of a high modulus fiber having a modulus of 525 grams per denier (480 grams per dtex) or greater and having an axial coefficient of thermal expansion of 2 ppm/° C. or less, based on the total amount of thermoplastic and high modulus fiber in the honeycomb cell walls; wherein the honeycomb has a coefficient of thermal expansion in the Z-dimension of 10 ppm/° C. or less as measured by ASTM E831.
    Type: Application
    Filed: December 15, 2006
    Publication date: November 20, 2008
    Inventors: Subhotosh Khan, Mikhail R. Levit, Gary Lee Hendren
  • Publication number: 20080145598
    Abstract: This invention relates to a honeycomb comprising matrix resin and paper, the paper comprising 50 to 80 parts by weight fibrous material having a modulus of 600 grams per denier (550 grams per dtex) or greater, 0 to 50 parts by weight powdered inorganic material, and 20 parts by weight or greater thermoplastic fiber, the improvement comprising the thermoplastic fiber is a binder for the paper and has a melting temperature above the curing temperature of the matrix resin; a glass transition temperature of greater than 100° C., and the weight average molecular weight of the thermoplastic polymer in the thermoplastic fibers changes 20% or less after being maintained for 10 minutes at the melting temperature. One embodiment of this invention includes an article comprising the aforesaid honeycomb, with such articles including a panel or an aerodynamic structure.
    Type: Application
    Filed: December 15, 2006
    Publication date: June 19, 2008
    Inventors: Mikhail R. Levit, Subhotosh Khan, Gary Lee Hendren
  • Publication number: 20080145600
    Abstract: This invention relates to an improved flame retardant honeycomb comprising high modulus fiber and a flame retardant thermoplastic binder having a melt point of from 120° C. to 350° C. and a limiting oxygen index of 26 or greater, methods for making the honeycomb, and articles comprising the honeycomb. In a preferred embodiment the paper in the honeycomb has a flame classification of UL-94 V-0.
    Type: Application
    Filed: December 15, 2006
    Publication date: June 19, 2008
    Inventors: Gary Lee Hendren, Subhotosh Khan, Mikhail R. Levit
  • Publication number: 20080145596
    Abstract: This invention relates to a honeycomb having cells comprising a paper, the paper in one embodiment comprising 3 to 30 parts by weight aliphatic polyamide binder, and 70 to 97 parts by weight of a poly(paraphenylene terephthalamide) fiber having a modulus of 600 grams per denier (550 grams per dtex) or greater, based on the total amount of aliphatic polyamide binder and PPD-T fiber in the paper; and wherein the paper has an average specific tensile index of 60 (lbs/in)/opsy (310 Nm/g) or greater. In another embodiment, the honeycomb is made from a paper comprising 30 to 50 parts by weight aliphatic polyamide binder, and 50 to 70 parts by weight of a poly(paraphenylene terephthalamide) fiber having a modulus of 600 grams per denier (550 grams per dtex) or greater, based on the total amount of aliphatic polyamide binder and PPD-T fiber in the paper; and wherein the paper has an average specific tensile index of 60 (lbs/in)/opsy (310 Nm/g) or greater.
    Type: Application
    Filed: December 15, 2006
    Publication date: June 19, 2008
    Inventors: Mikhail R. Levit, Subhotosh Khan, Gary Lee Hendren
  • Publication number: 20080145597
    Abstract: This invention relates to a honeycomb comprising cells having edges forming a face of the honeycomb, the face defined by a plurality of points and having an area of curvature wherein at least two of the points are located in different tangential planes, the walls of the cells comprising 5 to 50 parts by weight thermoplastic material having a melting point of from 120° C. to 350° C., and 50 to 95 parts by weight of a high modulus fiber having a modulus of 600 grams per denier (550 grams per dtex) or greater, based on the total amount of thermoplastic material and high modulus fiber in the walls; wherein less than 25 percent of the honeycomb cells in the area of curvature have a re-entrant angle of greater than 180 degrees. This invention also relates to articles including panels and/or aerodynamic structures comprising the honeycomb.
    Type: Application
    Filed: December 15, 2006
    Publication date: June 19, 2008
    Inventors: Gary Lee Hendren, Mikhail R. Levit, Subhotosh Khan
  • Publication number: 20080145601
    Abstract: This invention relates to an improved high performance honeycomb, methods for making the same, and articles including aerodynamic structures comprising the honeycomb, the honeycomb made with a paper that allows rapid impregnation of the honeycomb by structural resins while retarding excessive impregnation of node-line adhesives during manufacture. The honeycomb comprises a paper having a Gurley porosity of 2 seconds or greater and comprising high modulus fiber and thermoplastic binder having a melt point of from 120° C. to 350° C., wherein at least 30 percent by weight of the total amount of thermoplastic material is in the form of discrete film-like particles in the paper, the particles having a film thickness of about 0.1 to 5 micrometers and a minimum dimension perpendicular to that thickness of at least 30 micrometers.
    Type: Application
    Filed: December 15, 2006
    Publication date: June 19, 2008
    Inventors: Mikhail R. Levit, Subhotosh Khan, Gary Lee Hendren
  • Publication number: 20080145602
    Abstract: This invention relates to processes for making a honeycomb comprising cells having edges forming a face of the honeycomb, the face defined by a plurality of points and having an area of curvature wherein at least two of the points are located in different tangential planes, comprising the steps of: a) bonding a plurality of sheets along parallel lines of adhesive, the sheets comprising 5 to 50 parts by weight thermoplastic material having a melting point of from 120° C. to 350° C.
    Type: Application
    Filed: December 15, 2006
    Publication date: June 19, 2008
    Inventors: Gary Lee Hendren, Mikhail R. Levit, Subhotosh Khan
  • Publication number: 20080145599
    Abstract: This invention relates to processes of making a honeycomb comprising cells having edges forming a face of the honeycomb, the face defined by a plurality of points, at least two of the points located in different tangential planes, comprising the steps of: a) forming a honeycomb having expanded cells from a plurality of sheets comprising thermoplastic material having a melting point of from 120 to 350° C.
    Type: Application
    Filed: December 15, 2006
    Publication date: June 19, 2008
    Inventors: Subhotosh Khan, Gary Lee Hendren, Mikhail R. Levit