Patents by Inventor Richard E. Ludwig

Richard E. Ludwig 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).

  • Security paper from film-fibril sheets
    Patent number: 4310591
    Abstract: A security paper is provided in which identifying material is contained as an intercalary layer within the thickness of a bonded, nonwoven, polyethylene-film-fibril sheet having an opacity of at least 70% and a delamination resistance of at least 60 grams per centimeter. A process for making such paper includes forming an assembly of two unbonded, lightly consolidated, nonwoven, polyethylene film-fibril sheets containing identifying material between them, compressing the assembly in an unheated nip at 17 to 85 kilograms per centimeter of assembly width and then self-bonding the compressed assembly while under restraint by contact with a heated drum. Such security paper is useful for bank notes, stock certificates, paper currency and the like.
    Type: Grant
    Filed: August 28, 1980
    Date of Patent: January 12, 1982
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: Chi C. Lee, Richard E. Ludwig
  • Process for making security paper from film-fibril sheets
    Patent number: 4247318
    Abstract: A security paper is provided in which identifying material is contained in a plane within the thickness of a bonded, nonwoven polyethylene film-fibril sheet having an opacity of at least 70% and a determination resistance of at least 60 grams per centimeter. A process for making such paper includes forming an assembly of two unbonded, lightly consolidated, nonwoven, polyethylene film-fibril sheets containing identifying material between them, compressing the assembly in an unheated nip at 17 to 85 kilograms per centimeter of assembly width and then self-bonding the compressed assembly while under restraint by contact with a heated drum. Such security paper is useful for bank notes, stock certificates, paper currency and the like.
    Type: Grant
    Filed: January 30, 1979
    Date of Patent: January 27, 1981
    Assignee: E. I. Du Pont de Nemours and Company
    Inventors: Chi C. Lee, Richard E. Ludwig