Ink composition
An ink composition includes colorant, co-solvent system, acid (e.g., oleic, linoleic, undecanoic, dodecanoic, and/or tridecanoic acids), lithium, polymer as binder, and water. The co-solvent system is selected from i) from ˜9 to ˜25 wt % of sulfolane with no other co-solvent, ii) hydroxylated co-solvent, from ˜4 to ˜16 wt % of sulfolane, and at least 8 wt % of another non-hy-droxylated co-solvent; iii) hydroxylated co-solvent, from ˜7 to ˜16 wt % of sulfolane, and at least 3 wt % of the other non-hydroxylated co-solvent; and iv) a hydroxylated co-solvent and from ˜9 wt % to ˜16 wt % of sulfolane. When i) or ii) or iv) is used, at least 0.15 wt % acid and at least 200 ppm lithium are included; or when iii) is used, at least 0.25 wt % acid and at least 100 ppm lithium are included; or when iii) is used, at least 0.15 wt % acid and at least 150 ppm lithium are included.
1. An ink composition, comprising:
a colorant;
a co-solvent system selected from the group consisting of i) from about 9 wt % to about 25 wt % of sulfolane with no other co-solvent, ii) a hydroxylated co-solvent, from about 4 wt % to about 16 wt % of sulfolane, and at least 8 wt % of an other non-hydroxylated co-solvent; iii) a hydroxylated co-solvent, from about 7 wt % to about 16 wt % of sulfolane, and at least 3 wt % of the other non-hydroxylated co-solvent; and iv) a hydroxylated co-solvent and from about 9 wt % to about 16 wt % of sulfolane;
an acid selected from the group consisting of oleic acid, linoleic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, and combinations thereof;
lithium;
a polyurethane copolymer binder formed from the polymerization of a diisocyanate and at least three diols including a first diol containing a hydrophilic stabilizing group, and a second diol having less than 8 atoms in a backbone chain between two hydroxyl groups, wherein a mole percentage of the second diol is at least 30% of a total mole percentage of diol monomers in the polyurethane copolymer binder, and wherein an acid number of the polyurethane copolymer ranges from 50 to 70; and
water;
wherein any of:
when the co-solvent system is i) or ii) or iv), at least 0.15 wt % of the acid and at least 200 ppm of the lithium are included;
when the co-solvent system is iii), at least 0.25 wt % of the acid and at least 100 ppm of the lithium are included; or
when the co-solvent system is iii), at least 0.15 wt % of the acid and at least 150 ppm of the lithium are included.
2. The ink composition as defined in claim 1 wherein a viscosity of the ink composition ranges from about 1.5 mPa·s to about 5.0 mPa·s.
3. The ink composition as defined in claim 1 wherein the co-solvent system is i) and consists of the sulfolane alone.
4. The ink composition as defined in claim 1 wherein the co-solvent system is ii), or iii), or iv), and wherein the hydroxylated co-solvent is selected from the group consisting of 2-methyl-1,3-propanediol, 2-hydroxyethyl-2-pyrrolidinone, 2-ethyl-2-hydroxymethyl-1,3-propanediol, di-(2-hydroxyethyl)-5,5-dimethylhydantoin, glycerol, diethylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, dipropyleneglycol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 1-(2-hydroxyethyl)-2-imidazolidinone, 1,6-hexanediol, 1,5-pentanediol, and combinations thereof.
5. The ink composition as defined in claim 1 wherein when the co-solvent system is ii) or iii), the other non-hydroxylated co-solvent is selected from the group consisting of 2-pyrrolidinone, diethyleneglycol dimethyl ether, and combinations thereof.
6. The ink composition as defined in claim 1 , further comprising an additive chosen from a biocide, a non-ionic surfactant, and combinations thereof.
7. The ink composition as defined in claim 1 , including:
from about 2.0 wt % to about 6.5 wt % of the colorant; and
from about 1.0 wt % to about 3.0 wt % of the polyurethane copolymer binder.
8. A print cartridge, comprising:
a fluid reservoir;
a fluid ejector in fluid communication with the fluid reservoir;
a nozzle in fluid communication with the fluid ejector;
the ink composition of claim 1 present in the fluid reservoir; and
an anti-evaporative layer present at an interface between air and the ink composition in an orifice of the nozzle, the anti-evaporative layer formed during uncapped non-use, thereby reducing evaporation of the water from the ink composition.
9. The print cartridge as defined in claim 8 wherein:
the co-solvent system is ii) or iii) or iv);
the hydroxylated co-solvent is selected from the group consisting of 2-methyl-1,3-propanediol, 2-hydroxyethyl-2-pyrrolidinone, 2-ethyl-2-hydroxymethyl-1,3-propanediol, di-(2-hydroxyethyl)-5,5-dimethylhydantoin, glycerol, diethylene glycol, triethylene glycol, tripropylene glycol, tetraethylene glycol, dipropyleneglycol, 3-methyl-1,3-butanediol, 3-methyl-1,5-pentanediol, 1-(2-hydroxyethyl)-2-imidazolidinone, 1,6-hexanediol, 1,5-pentanediol, and combinations thereof; and
when the non-hydroxylated co-solvent is ii) or iii), the other non-hydroxylated co-solvent is selected from the group consisting of 2-pyrrolidinone, diethyleneglycol dimethyl ether, and combinations thereof.
10. A high speed printing method, comprising:
selecting the ink composition of claim 1 ; and
printing the ink composition using a printer having a drop frequency ranging from about 24 kHz to about 36 kHz;
wherein a thick thin line print image quality defect is reduced in a resulting image.
11. The ink composition as defined in claim 1 wherein the co-solvent system is ii), or iii), or iv), and wherein the hydroxylated co-solvent is 2-hydroxyethyl-2-pyrrolidinone.
12. The ink composition as defined in claim 1 wherein the co-solvent system is ii) or iii), and wherein the other non-hydroxylated co-solvent is 2-pyrrolidinone.
13. An ink composition, comprising:
a colorant;
a co-solvent system including:
2-hydroxyethyl-2-pyrrolidinone as a hydroxylated co-solvent; and
from about 9.7 wt % to about 10.5 wt % of sulfolane alone as a non-hydroxylated co-solvent;
an acid selected from the group consisting of oleic acid, linoleic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, and combinations thereof;
lithium;
a polymer binder; and
water;
wherein at least 0.15 wt % of the acid and at least 200 ppm of the lithium are included.
14. An ink composition, comprising:
a colorant;
a co-solvent system including:
2-hydroxyethyl-2-pyrrolidinone as a hydroxylated co-solvent;
about 4.0 wt % of sulfolane; and
about 8.8 wt % of 2-pyrrolidinone as an other non-hydroxylated co-solvent;
lithium present in an amount of about 212 ppm;
an acid present in an amount of about 0.18 wt %, the acid selected from the group consisting of oleic acid, linoleic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, and combinations thereof;
a polymer binder; and
water.
15. An ink composition, comprising:
a colorant;
a co-solvent system including:
2-hydroxyethyl-2-pyrrolidinone as a hydroxylated co-solvent; and
about 7.0 wt % of sulfolane and about 3.5 wt % of 2-pyrrolidinone as an other non-hydroxylated co-solvent;
an acid selected from the group consisting of oleic acid, linoleic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, and combinations thereof;
lithium;
a polymer binder; and
water;
wherein:
the lithium is present in an amount of at least 150 ppm; and
the acid is present in an amount of about 0.18 wt %.
16. An ink composition, comprising:
a colorant;
a co-solvent system including:
2-hydroxyethyl-2-pyrrolidinone as a hydroxylated co-solvent; and
about 7.0 wt % of sulfolane and about 3.5 wt % of 2-pyrrolidinone as an other non-hydroxylated co-solvent;
an acid selected from the group consisting of oleic acid, linoleic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, and combinations thereof;
lithium;
a polymer binder; and
water;
wherein:
the lithium is present in an amount of about 100 ppm; and
the acid is present in an amount of at least 0.25 wt %.