Methods and compositions for increasing ink clay loading in heatset ink formulations while maintaining ink gloss, and ink formulations produced therefrom
In some variations, this disclosure provides a surface-modified hydrophobic clay composition for an ink formulation, the composition comprising up to 99 wt % clay particles with a particle-size distribution characterized in that at least 10% are smaller than 0.2 microns, at least 25% are smaller than 0.5 microns, and at least 95% are less than 5 microns; and from about 1 wt % to about 10 wt % of one or more organic compounds selected from quaternary ammonium compounds, organic acids, fatty acids, organic silanes, or organic polysilanes. The surface-modified hydrophobic clay composition may be produced by various methods, including a slurry method or a dry-mixing method. Ink clay loadings in heatset ink formulations may be increased to 10-15% without losing ink gloss. Inks may be produced with lower solvent, resin, and/or pigment concentrations, thereby reducing cost.
1. A surface-modified hydrophobic clay composition for an ink formulation, said composition comprising:
(i) from more than 0 to 99 wt % of clay particles with a particle-size distribution characterized in that 40% to 60% of said clay particles are smaller than 0.2 microns, 70% to 98% of said clay particles are smaller than 0.5 microns, and substantially all of said clay particles are less than 5 microns; and
(ii) from about 1 wt % to about 5 wt % of one or more quaternary ammonium compounds given by the formula [R 1 R 2 R 3 R 4 N + ][X − ], wherein each of R 1 , R 2 , R 3 , and R 4 are independently selected hydrocarbon groups or chains, and wherein X − is a monovalent anion.
2. The composition of claim 1 , wherein at least 50% of said clay particles are smaller than 0.2 microns.
3. The composition of claim 1 , wherein said clay particles comprising one or more clays selected from the Kaolin group of minerals comprising kaolinite, dickite, halloysite, nacrite, montmorrilite, or any other polymorph of Al 2 Si 2 O 5 (OH) 4 .
4. The composition of claim 3 , wherein said clay particles are kaolin clay particles.
5. The composition of claim 1 , wherein at least one of R 1 , R 2 , R 3 , and R 4 is selected from C 10 -C 24 chains.
6. The composition of claim 5 , wherein at least two of R 1 , R 2 , R 3 , and R 4 are selected from C 10 -C 24 chains.
7. The composition of claim 1 , wherein at least one of R 1 , R 2 , R 3 , and R 4 is selected from C 1 -C 9 chains.
8. The composition of claim 7 , wherein at least two of R 1 , R 2 , R 3 , and R 4 are selected from C 1 -C 9 chains.
9. The composition of claim 1 , wherein at least one of R 1 , R 2 , R 3 , and R 4 is a methyl group.
10. The composition of claim 9 , wherein at least two of R 1 , R 2 , R 3 , and R 4 are methyl groups.
11. The composition of claim 1 , wherein two of R 1 , R 2 , R 3 , and R 4 are methyl groups and wherein the other two of R 1 , R 2 , R 3 , and R 4 are selected from C 16 -C 18 chains.
12. The composition of claim 1 , wherein X − is an organic anion.
13. The composition of claim 1 , wherein X − is an inorganic anion.
14. The composition of claim 13 , wherein X − is a halide anion.
15. An ink formulation containing a surface-modified hydrophobic clay composition, said composition comprising:
(i) from more than 0 to 99 wt % of clay particles with a particle-size distribution characterized in that 40% to 60% of said clay particles are smaller than 0.2 microns, 70% to 98% of said clay particles are smaller than 0.5 microns, and substantially all of said clay particles are less than 5 microns; and
(ii) from about 1 wt % to about 10 wt % of one or more organic compounds selected from the group consisting of a quaternary ammonium compound, an organic acid, a fatty acid, an organic silane, an organic polysilane, and combinations thereof,
wherein said ink formulation has an ink gloss of least 90%.
16. The ink formulation of claim 15 , wherein said composition comprises from about 2 wt % to about 8 wt % of said one or more organic compounds.
17. The ink formulation of claim 15 , wherein at least 50% of said clay particles are smaller than 0.2 microns.
18. The ink formulation of claim 15 , wherein said clay particles comprising one or more clays selected from the Kaolin group of minerals comprising kaolinite, dickite, halloysite, nacrite, montmorrilite, or any other polymorph of Al 2 Si 2 O 5 (OH) 4 .
19. The ink formulation of claim 18 , wherein said clay particles are kaolin clay particles.