The Standard Register Company

Michael E Seitz

Gary W Doll

William F Pinell

Richard Lynn Shields

Frank V Parenti

Naoki Tsuda

A process for making melamine-formaldehyde microcapsules in an aqueous solution containing a high concentration of a water miscible or water soluble organic solvent is provided. The aqueous solution is prepared and a water insoluble melamine-formaldehyde pre-condensate is dissolved therein by adjusting the temperature and organic solvent concentration of the aqueous solution such that the melamine-formaldehyde pre-condensate is barely soluble therein. A substance to be encapsulated, preferably an oily solution containing a dyestuff precursor, is dispersed into the aqueous solution to form an emulsion, the melamine-formaldehyde pre-condensate being insoluble in the substance to be encapsulated. The melamine-formaldehyde pre-condensate is separated from the aqueous solution onto droplets of the substance to be encapsulated and the self-condensation reaction of the phase-separated melamine-formaldehyde pre-condensate initiated to form capsule walls around the droplets, thereby producing melamine-formaldehyde microcapsules in the aqueous solution containing a high concentration of a water miscible or water soluble organic solvent.

Melamine formaldehyde microencapsulation in aqueous solutions containing

A high solids content, aqueous, microcapsule-containing printing ink is prepared by forming microcapsules in situ in a printing ink vehicle. The microcapsules are preferably prepared by interfacial polymerization or interfacial crosslinking between a reactant, such as a polyisocyanate dissolved in an oily solution and a coreactant such as a polysalt of casein and diethylene triamine present in an aqueous solution into which the oily solution is dispensed. The aqueous solution contains water and preferrably a non-volatile diluent such as a non-reducing sugar, for example methyl glucoside. The oil-containing microcapsules contain an oil solvent and a mixture of dye precursors which upon reaction with a color developer produces an intense black image. The printing ink preferably has a 60-70% by weight solids content and may be used as a low-coat-weight CB coating for preparing carbonless copy paper.

High solids CB printing ink which produces a black image

A process for producing melamine-formaldehyde microcapsules using a reactive protective colloid is provided. The reactive protective colloid is prepared by reactively coupling a surface active polymer with a first melamine-formaldehyde pre-condensate. An aqueous solution which includes the reactive protective colloid and a second melamine-formaldehyde pre-condensate is then prepared. A substance to be encapsulated, preferably an oily solution containing a dyestuff precursor, is dispersed as droplets into the aqueous solution. The reactive protective colloid surrounds the droplets to form an emulsion. The second melamine-formaldehyde pre-condensate and the reactive protective colloid are made to self-condense to form melamine-formaldehyde microcapsule walls around the droplets of the substance to be encapsulated.

Microencapsulation process using melamine-formaldehyde and microcapsules

A process for the production of microcapsules containing a core material is provided and includes the steps of providing a polar solvent, and adding thereto a dispersion of a tertiary aliphatic isocyanate and a core material in an oleophilic liquid and an amine-containing composition having at least three primary amine groups to form a mixture. The mixture containing these components is reacted to form microcapsules containing the core material. The tertiary aliphatic isocyanate preferably comprises an adduct of m-tetramethylxylene diisocyanate and trimethylolpropane. The core material may contain a dyestuff precursor which is capable of reacting with a color developer to form a color. The microcapsules containing dyestuff precursor may be used to coat a support sheet to form carbonless copy paper.

Microencapsulation using tertiary aliphatic isocyanate capsule wall

A CF ink and process which can be applied to a support sheet by standard transfer-litho press is provided. The nonvolatile printing ink which is capable of color development may be used to produce a CF carbonless copy sheet, or, in combination with a high solids, aqueous-based CB ink, to produce a CFB carbonless copy sheet. The ink includes from about 25 to 35% of a non-volatile oil, 25 to 35% of an acidic color developer, 20 to 50% filler, and 4 to 15% dispersed wax particles, all percentages by weight.

CF ink and tandem printing process

A high solids content, aqueous, microcapsule-containing printing ink is prepared by forming microcapsules in situ in a printing ink vehicle. The microcapsules are preferably prepared by interfacial polymerization or interfacial crosslinking between a reactant, such as a polyisocyanate dissolved in an oily solution and a coreactant such as a polysalt of casein and diethylene triamine present in an aqueous solution into which the oily solution is dispensed. The aqueous solution contains water and a non-volatile diluent such as a non-reducing sugar, for example methyl glucoside. The printing ink preferably has a 60-70% by weight solids content and may be used as a low-coat-weight CB coating for preparing carbonless copy paper.

Carbonless copy paper sheet bearing a high solids CB printing ink

A high solids contents, aqueous-based, self-contained printing ink is provided including, a non-volatile diluent, an acidic color developer, a binder, and a water soluble surfactant which is compatible with the binder in the ink, but which is incompatible with the binder when the ink has dried. The high solids, self-contained printing ink further includes microcapsules containing a dyestuff precursor that is capable of reacting with the acidic color developer to form a color. The ink may be used to prepare self-contained carbonless copy sheets.

High solids self-contained printing ink

A high solids content, aqueous, color developer-containing printing inks having as it main ingredients water, a non-volatile diluent and an acidic color developer such as zinc salicylate or a phenolic resin. The high CF printing ink preferably has a 50-70% by weight solids content and may be used as a low-coat-weight CF coating for preparing carbonless copy paper by coating the high solids CF printing ink on a support sheet at a coat weight of less than 3 gm/m.sup.2.

High solids CF printing ink

Microencapsulated load bearers to prevent the premature rupture of dye precursor-containing microcapsules are formed concurrently in the same microencapsulation process in which oil/dye precursor-containing microcapsules are formed by emulsifying an oily mixture, containing therein a dye-precursor solution and non-rupturable core particles, as droplets into an aqueous solution. The core particle and oil/dye precursor droplets are then microencapsulated to form a binary microcapsule mixture consisting of microencapsulated load bearers and oil/dye precursor-containing microcapsules, respectively. This binary microcapsule mixture in an appropriate solvent vehicle may be used as a coating for the preparation of carbonless copy paper.

Carbonless copy paper coating containing microencapsulated load bearers

High solids CB printing ink containing a protective colloid blend

Process for making a high solids CB printing ink

Microcapsules having hard, thick walls are formed by dispersing an oily solution containing a crosslinking agent in an aqueous solution, and forming a polysalt in the aqueous solution, the polysalt including a high molecular weight polyanion and a low molecular weight polycationic polyamine having a functionality of at least three. The polyanion is preferably casein. The microcapsules may be used in a CB ink for preparing carbonless copy paper.

Production of microcapsules

High solids CB printing ink

Microcapsules having hard, thick walls are formed by dispersing an oily solution containing a crosslinking agent in an aqueous solution, and forming a polysalt in the aqueous solution, the polysalt including a high molecular weight polyanion and a polycationic polyamine having a functionality of at least three. The polyanion is preferably casein. If the surface of the microcapsules formed in the aqueous solution is lipophilized, the microcapsules easily separate from the solution by filtration. By use of a suitable wetting agent, the filter cake can be used in place of the pigment in any conventional printing ink. The microcapsules may be used in carbonless copy paper technology.

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Miamisburg, OH, United States of America

Michael E Seitz