US 4,100,103 AGranted

Capsule manufacture

AssigneeNCR Corporation

InventorsPeter L. Foris, Robert W. Brown, Paul S. Phillips, Jr.

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Abstract

A process is disclosed for performing encapsulation, en masse, by an in situ polymerization reaction to yield capsule wall material. The polymerization comprises a reaction between melamine and formaldehyde and/or polycondensation of monomeric methylol melamine or etherified methylol melamine, or a low molecular weight polymer thereof, in an aqueous vehicle and the reaction is conducted in the presence of negatively-charged, carboxyl-substituted, linear aliphatic hydrocarbon polyelectrolyte material dissolved in the vehicle. Liquid-liquid phase separation is accomplished and maintained by increase in the molecular weight of the resulting condensation polymer without further dilution of the manufacturing vehicle. The negatively-charged polyelectrolyte material is required and has an apparent effect of controlling or modifying the polymerization reaction. The disclosed encapsulation process permits manufacture of micro-capsules in concentrations of capsule to capsule manufacturing vehicle higher than previously possible.

Claims17

Dependent claims

A process for manufacturing minute capsules, en masse, in an aqueous manufacturing vehicle, comprising:

establishing an agitating aqueous system comprising
(A) melamine and formaldehyde,
(B) monomeric methylol melamine or a low molecular weight polymer thereof or
(C) monomeric methylated methylol melamine or a low molecular weight polymer thereof as a starting material or mixtures of any of said starting materials, about 0.4 to about 15 percent by weight, based on the weight of aqueous manufacturing vehicle, of a system modifier material selected from the group consisting of poly(ethylene-co-maleic anhydride), poly(methyl vinyl ether-co-maleic anhydride), poly(acrylic acid), poly(propylene-co-maleic anhydride), poly(butadiene co-maleic anhydride) and poly(vinyl acetate-co-maleic anhydride), and particles of an intended capsule core material substantially insoluble in the system, in which agitating system the modifier is present prior to the addition of said particles, whereby said starting material polycondenses to form a condensation polymer resulting in
(i) liquid-liquid phase separation of the resulting condensation polymer above a molecular weight to be soluble in the system and
(ii) continued polycondensation of the separated polymerization product to give solid capsule wall material individually surrounding particles of the dispersed intended capsule core.

3 more elements

Dependencies are inferred from the claim text.