Providing opaque ink jetted image
View Patent ↗Inkjet printing is carried out on a substrate having a topmost layer comprising aqueous soluble multivalent metal cations and a hydrophilic polymeric binder. An aqueous inkjet ink composition is drawn from a main fluid supply as a continuous stream that is broken into both printing drops and non-printing drops, forming a white printed image on the substrate with the printing drops. The non-printing drops are collected and returned to the main fluid supply. The aqueous inkjet ink composition comprises particles of titanium dioxide in an amount of at least 4 to 15 weight %. The particles of titanium dioxide have a 95 th percentile particle size of less than 200 nm, a 50 th percentile particle size of less than 130 nm, and are dispersed using a dispersing polymer comprising acidic groups. The weight ratio of the particles of titanium dioxide to the dispersing polymer is 19:1 to 2:1.
1. A method of inkjet printing, comprising:
providing a substrate that comprises a topmost layer comprising at least 30 weight % of one or more aqueous soluble multivalent metal cations and at least 0.05 g/m 2 of a hydrophilic polymeric binder,
ink jetting an aqueous inkjet ink composition from a main fluid supply as a continuous stream that is broken into both printing drops and non-printing drops, forming a white printed image having an opacity of at least 30% on the substrate with the printing drops,
collecting and returning the non-printing drops to the main fluid supply,
wherein:
the aqueous inkjet ink composition comprises particles of titanium dioxide in an amount of at least 4 weight % and up to and including 15 weight %, based on the total weight of the aqueous inkjet ink composition;
the particles of titanium dioxide have a 95 th percentile particle size of less than 200 nm and a 50th percentile particle size of less than 130 nm;
the particles of titanium dioxide are dispersed within the aqueous inkjet ink composition with a dispersing polymer comprising acidic groups; and
the weight ratio of the particles of titanium dioxide to the dispersing polymer is from 19:1 to and including 2:1,
the aqueous inkjet ink composition further comprising an aqueous medium comprising at least 50 weight % water content based on the total weight of the aqueous inkjet ink composition, and water comprises at least 50 weight % of all solvents.
2. The method of claim 1 , wherein the weight ratio of the particles of titanium dioxide to the dispersing polymer is from 13:1 to and including 4:1.
3. The method of claim 1 , wherein the dispersing polymer has a weight average molecular weight of at least 5,000 and up to and including 100,000, and an acid value of at least 100 and up to and including 500.
4. The method of claim 1 , wherein the particles of titanium dioxide have a 20 th percentile particle size of at least 50 nm, a 95 th percentile particle size of less than 150 nm, and a 50 th percentile particle size of less than 100 nm and the white printed image has an opacity of at least 40%.
5. The method of claim 1 , wherein:
the dispersing polymer comprises recurring units comprising hydroxy benzoic acid groups, and has a weight average molecular weight of at least 5,000 and up to and including 100,000, and an acid value of at least 100 and up to and including 500; and
the weight ratio of the titanium dioxide particles to the dispersing polymer is from 9:1 to and including 5:1.
6. The method of claim 1 , wherein the aqueous inkjet ink composition is capable of providing a white printed image of at least 40%.
7. A method of inkjet printing, comprising:
providing a substrate, and
ink jetting an aqueous inkjet ink composition to form a printed image on the substrate,
wherein the aqueous inkjet ink composition comprises:
pigment colorant particles that are present in an amount of at least 4 weight % and up to and including 15 weight %, wherein the pigment colorant particles have a 95 th percentile particle size of less than 200 nm and a 50 th percentile particle size of less than 130 nm;
a dispersing polymer that is a hexyloxy benzoic acid polymer;
a humectant having a molecular weight of less than 1,000; and
an aqueous medium having a water content of at least 50 weight % and water comprises at least 50 weight % of the total solvents,
wherein the weight ratio of the pigment colorant particles to the dispersing polymer is from 19:1 to and including 2:1.
8. The method of claim 1 , wherein the dispersing polymer comprises recurring units comprising hexyloxy benzoic acid groups in an amount of at least 50 mol % and up to and including 90 mol % based on all recurring units.
9. An ink set comprising two or more aqueous inkjet ink compositions,
at least one of which aqueous inkjet ink compositions provides a white printed image having an opacity of at least 30% when inkjet printed onto a substrate that comprises a topmost layer comprising at least 30 weight % of one or more aqueous soluble multivalent metal cations and at least 0.05 g/m 2 of a hydrophilic polymeric binder; and
at least one other aqueous inkjet ink composition provides a color other than white when inkjet printed onto the substrate,
wherein:
the aqueous inkjet ink composition that provides a white printed images having an opacity of at least 30%, comprises particles of titanium dioxide in an amount of at least 4 weight % and up to and including 15 weight %, based on the total weight of the aqueous inkjet ink composition;
the particles of titanium dioxide have a 95 th percentile particle size of less than 200 nm and a 50 th percentile particle size of less than 130 nm;
the particles of titanium dioxide are dispersed within the aqueous inkjet ink composition with a dispersing polymer comprising acidic groups; and
the weight ratio of the particles of titanium dioxide to the dispersing polymer is from 19:1 to and including 2:1,
the aqueous inkjet ink composition further comprising an aqueous medium comprising at least 50 weight % water content based on the total weight of the aqueous inkjet ink composition, and water comprises at least 50 weight % of all solvents.