The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 26, 1981
Filed:
Oct. 22, 1979
Emil A Lawton, Sherman Oaks, CA (US);
Whittaker Corporation, Los Angeles, CA (US);
Abstract
An improved imbibitive polymer is prepared by a method which comprises linearly polymerizing methyl acrylate with a free radical-yielding catalyst while the acrylate is suspended in an aqueous medium containing selected suspending agent and while cross-linking the acrylate to a low level with selected cross-linking agent in a concentration of about 0.02-3%, by weight of the acrylate. The aqueous medium is heated and agitated during the reaction to keep the acrylate in fine suspension so that polymethyl acrylate beads are formed which do not agglomerate and which are capable of imbibing liquids having solubility parameters of about 8.5-11.5 Hildebrands. The catalyst concentration is usually about 1%, by weight of the methyl acrylate, and benzoyl peroxide and azo-bis-isobutyronitrile are preferred as the catalyst. The cross-linking agent is preferably divinyl benzene, 1,6-hexane-diol acrylate, ethylene glycol dimethacrylate and mixtures thereof, and is preferably used in a concentration of about 0.11-0.334%, by weight of the methyl acrylate. The suspending agent comprises a viscosity-increasing liquid such as acrylamide and/or sodium polyacrylate, with or without a solid suspending agent such as talc, bentonite, calcium carbonate, kaolin and mixtures thereof. Preferably an additional amount of catalyst is utilized near the end of the reaction to inhibit coalescence or agglomeration of the formed polymethyl acrylate beads.