| abstract |
This disclosure is directed to a high solid, low viscosity carbonless paper gelatin base microcapsule system producing microcapsules having sizes characteristically from about 3 to about 10 microns (micrometers) and being characterized as single oil drop microcapsules. This system of microcapsules is further characterized by a high solids content, viz., from about 25 to about 50 weight percent solids, in combination with a low viscosity, viz., ranging from about 10 to about 60 centipoises and having a high microcapsule payload (core concentration by weight based on total capsule weight), e.g., of 80+wt. % and preferbly about 90 weight percent and higher, in aqueous suspensions. The combination of high solid content and high microcapsule payload, with low viscosity enables delivery of a high concentration of solid microcapsules at reasonably high coating speeds via comparatively inexpensive conventional pumping systems and paper coating systems. The present gelatin based microcapsule system is arrived at by blending low Bloom strength gelatin, e.g., about 100 to 200 Bloom strength, with a blend of at least two anionic phase inducers comprising (1) sodium hexametaphosphate (SHMP), and at least one of: (2) a copolymer of vinyl methyl ether and maleic anhydride (PVM/MA), (3) a copolymer of ethylene and maleic anhydride (E/MA), (4) gum arabic and (5) carboxy methyl cellulose (CMC). |