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C21-dicarboxylic acid anhydride and size agents and sizing process

US 3,821,075 A · Inventors: BILLS A

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Listed from its USPTO record in Patent Yard's full-term archive. Its claims, description and drawings are in the USPTO PDF and on Google Patents, and the Claude kit works from them.

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Why it's free to use

  • Granted June 28, 1974. A patent granted before 1976 lasted at most 17 years from grant, so its term ended by June 28, 1991.
  • We check US rights only. Old patents can still inspire new ones: improvements may be patentable.
FiledOctober 18, 1973
GrantedJune 28, 1974
Term endedJune 28, 1991
Application number—
Classification (CPC)D21H17/14
Length5 pages

Timeline

Timeline From USPTO dates

197419761978198019821984198619881990Application filedOct 18, 1973Patent grantedJune 28, 1974Term endedJune 28, 1991

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Official USPTO records

Full published documentText and every drawing sheet as a PDF.USPTOFile historyStatus, office actions, notices, fee records and petitions.USPTO Patent CenterPatent Public Search recordSearchable full text and bibliographic data.USPTO

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