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US 4,785,048 AGranted
Polyurea and polyurea-epoxy microcapsules
AssigneeMoore Business Forms, Inc.
InventorHung-Ya Chao
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Abstract
An improved process for the production of microcapsules by the use of hydrogen transfer polymerization in the presence of a mixture of emulsifiers including either an aqueous solution of a sodium salt of naphthalene-sulfonic acid-formaldehyde condensate or diphenyloxide disulfonate with a polyvinyl alcohol. The process is particularly useful for the production of microcapsules containing a colorless dye intermediate used in carbonless copy paper (CCP) applications.
Claims4
A process for the production of polyurea and polyurea/epoxy microcapsules, said process comprising the steps of:
- a. mixing an oil-core material containing a colorless dye and a high boiling point carrier solvent with a polyisocyanate or a polyisocyanate-epoxy resin mixture;
- b. dispersing the resultant solution into an aqueous solution of an emulsifying mixture, said mixture comprising a first emulsifier component of a protective colloid and a second emulsifier component of a sodium salt of a napthalene sulfonic acid formaldehyde condensate or diphenyloxide disulfonate, in order to form an oil-in-water emulsion;
- c. adding a water-soluble polyamine into the emulsion;
- d. stirring the emulsion to complete the reaction.
1 more element
Dependencies are inferred from the claim text.