Aqueous printing vehicle

A process for preparing an aqueous polymer dispersion having an aqueous external phase of a water-soluble, glyceride oil adduct and an internal phase of minute vinyl aromatic polymer particles uniformly dispersed therein, said process being conducted under conditions sufficient to provide a dry solids content of at least 45% by weight and a free monovinyl aromatic monomer content of less than 0.7% by weight of the total aqueous dispersion weight, said process comprising the steps of:

• A. reacting at least one dicarboxylic acid selected from the group consisting of an alpha, beta-ethylenically unsaturated dicarboxylic acid and an alpha, beta-ethylenically unsaturated dicarboxylic acid anhydride with an unsaturated glyceride oil under adduct reaction conditions sufficient to provide an oil adduct containing at least 2 moles to about 4.5 moles of the dicarboxylic acid per equivalent of unsaturation in the unsaturated glyceride oil,
• B. neutralizing the oil adduct with an aqueous tertiary amine solution to a pH of greater than 7.0 but less than 10.0 and thereby providing a tertiary amine water-soluble salt of said oil adduct,
• C. initiating, in the presence of persulfate catalyst, the polymerization of the internal phase in a polymerization media comprised of at least a portion of the tertiary amine water-soluble oil adduct and a monovinyl aryl monomer,
• D. incrementally adding additional vinyl aryl monomer and additional persulfate catalyst at a predetermined rate to the polymerization media while maintaining the temperature of the reaction media at a temperature of less than 200.degree. F.,
• E. continuing the polymerization of monovinyl aryl monomer under conditions of (D) above for a period of time and under conditions sufficient to provide a weight ratio of water-soluble adduct to polymerizable monomer constituents of 1:3 to about 2:3,
• F. permitting substantially all of the monovinyl aryl monomers in the polymerization media to be polymerized via the persulfate catalyst, and
• G. polymerizing the residual monovinyl aryl monomers by adding a peroxide catalyst and a promoter to the polymerization media and permitting the polymerization to continue for a period of time and under conditions sufficient to reduce the total free monovinyl aryl monomers to a level of less than 0.7% by weight of the aqueous polymer dispersion weight.

In a method for providing overprint varnish on a printed cellulosic article wherein a pervious, cellulosic substrate is printed with a printing ink to provide a printed article, an aqueous vehicle is applied as continuous film coating upon the surface of the printed article, and permitting the aqueous coating to dry and thereby provide printed article having the aqueous vehicle solids as a coating film thereon, the improvement which comprises the utilization of an aqueous polymer dispersion as the aqueous coating vehicle, said aqueous polymer dispersion consisting essentially of:

• a. a continuous, aqueous external phase consisting essentially of an adduct reaction product of at least one dicarboxylic acid selected from the group consisting of an alpha, beta-ethylenically unsaturated dicarboxylic acid and an alpha, beta-ethylenically unsaturated dicarboxylic acid anhydride and an unsaturated glyceride oil, said adduct reaction product being neutralized with an aqueous solution of a tertiary amine in an amount sufficient to provide a water-soluble, tertiary amine salt reaction product having a pH within the range of 7.0 to 10.0,
• b. a non-continuous, internal phase of minute, monovinyl aromatic polymer particles having an average particle size of less than 0.4 micron uniformly dispersed within said external phase,
• said polymer dispersion being further characterized as containing (on total weight basis) at least 40% by weight dry solids of said external phase and said internal phase, less than 0.7% by weight unpolymerized monovinyl aromatic monomer, at least one part to less than two parts external phase dry solids for each three parts by weight of dry internal phase solids, and a sufficient amount of water to permit the aqueous coating of the printed cellulosic substrate therewith.

In a method for printing pervious cellulosic substrates, such as paper and paperboards, wherein a water-type aqueous ink vehicle containing color imparting and other ink additives is employed to impregnate the substrate surface by rotogravure and flexographic printing means to provide printed substrates thereof, the improvement which comprises the printing thereof with a press-ready ink formulation containing an aqueous polymer dispersion as a major ink binder (on a dry ink binder solids basis), said polymer dispersion comprising:

• a. a continuous, aqueous external phase consisting essentially of an adduct reaction product of at least one dicarboxylic acid selected from the group consisting of an alpha, beta-ethylenically unsaturated dicarboxylic acid and an alpha, beta-ethylenically unsaturated dicarboxylic acid anhydride and an unsaturated glyceride oil, said adduct reaction product being neutralized with an aqueous solution of a tertiary amine in an amount sufficient to provide a water-soluble, tertiary amine salt reaction product having a pH within the range of 7.0 to 10.0, and
• b. a non-continuous, internal phase of minute polymer particles having an average particle size of less than 0.4 micron uniformly dispersed within said external phase,
• said polymer dispersion being characterized as contining at least one part to less than two parts external phase dry weight solids for each three parts by weight dry internal phase solids, the total dry solids weight of said external phase and said internal phase being at least 40% with the remaining non-solids portion of said polymer dispersion consisting essentially of water, said polymer dispersion being further characterized as containing less than 0.5% by weight monomeric styrene;
• said press-ready ink being characterized as having a No. 2 Zahn cup value between about 25 to about 50 seconds and a total dry ink solids weight ranging from about 40 to about 80% by weight, said press-ink being further characterized as having a total dry solids weight between about 40 to about 55% by weight and pigment to binder ratio between about 1:2 to about 1:1 when the major coloring agent (total coloring agent weight basis) is an organic coloring agent;
• and between 55 to about 80% by weight total dry solids and a pigment to binder ratio from about 3:2 to about 5:2 when the major coloring agent (total coloring agent weight basis) is an inorganic coloring agent.

A printing ink composition suitable for use under ambient printing conditions and containing, uniformly dispersed throughout the ink composition, a polymer dispersion as a principal ink vehicle on a weight basis, said printing ink composition comprising an admixture of:

• A. a polymer dispersion comprising:
• a. a continuous, aqueous external phase consisting essentially of an adduct reaction product of at least one dicarboxylic acid selected from the group consisting of an alpha, beta-ethylenically unsaturated dicarboxylic acid and an alpha, beta-ethylenically unsaturated dicarboxylic acid anhydride and an unsaturated glyceride oil, said adduct reaction product being neutralized with an aqueous solution of a tertiary amine in an amount sufficient to provide a water-soluble, tertiary amine salt reaction product having a pH within the range of 7.0 to 10.0,
• b. a non-continuous, internal phase of minute, monovinyl aromatic polymer particles having an average particle size of less than 0.4 micron uniformly dispersed within said external phase, said polymer dispersion being further characterized as containing (on total dry weight basis) at least 40% by weight of said external phase and said internal phase, less than 0.5% by weight monovinyl aromatic monomer, and at least one part to less than two parts external phase dry solids for each three parts by weight of dry internal phase solids, and
• B. a color imparting agent of at least one member selected from the group consisting of an organic color agent and an inorganic coloring agent with the proviso that when the major coloring agent (on a total dry solid coloring agent weight basis) is an organic coloring agent, the ink composition contains from at least one part by weight to less than two parts by weight organic coloring agent for each two parts by weight polymer dispersion dry solids, and that when the major coloring agent (total dry solids coloring agent weight basis) is an inorganic coloring agent, the ink composition contains from about 3 to 8 parts by weight inorganic coloring agent for each two parts by weight of dry polymer dispersion solids,
• said ink composition being further characterized as containing at least 40% by weight dry solids and a sufficient amount of (A), (B), ink additives and water to provide a No. 2 Zahn cup reading of between 25-50 seconds, with the further proviso that when the ink composition contains organic coloring agents as a major coloring agent (on a weight basis), the total dry solids content of said printing ink composition ranges from about 40 to about 55% and when the inorganic coloring agents are a major color agent, the total dry solids content of said ink composition ranges from at least 55 to about 80% by weight.