Aqueous particle-free color inkjet ink composition
An aqueous particle-free inkjet ink composition has a pH of 7 to 9, and consists essentially of: (A) water-soluble dye colorants present in a total amount of 2-10 weight %, (B) a water-soluble polymer present in an amount of 1-4 weight %, and an aqueous medium consisting essentially of water. The water-soluble polymer has an acid number ≥130 and a molecular weight of 5,000 to 20,000. It comprises: (a) 55-80 mol % of recurring units derived from ethylenically unsaturated polymerizable monomers selected from substituted or unsubstituted styrenes, (meth)acrylates, and combinations thereof, each (meth)acrylate comprising either a pendant phenyl group or an alkyl ester group having 12 to 20 carbon atoms; and (b) 20-35 mol % of recurring units comprising (meth)acrylic acid, all based on total water-soluble polymer recurring units. The one or more water-soluble dye colorants are chosen singly or collectively to provide a hue other than black.
1. An aqueous particle-free inkjet ink composition that has a pH of at least 7 and up to and including 9, and consists essentially of:
(A) one or more water-soluble dye colorants present in a total amount of at least 2 weight % and up to and including 10 weight %, based on the total weight of the aqueous particle-free inkjet ink composition, wherein the one or more water-soluble dye colorants are water-soluble, non-black dyes chosen from acid dyes, direct dyes, reactive dyes, and food dyes,
(B) a water-soluble polymer present in an amount of at least 1 weight % and up to and including 4 weight %, based on the total weight of the aqueous particle-free inkjet ink composition, and
(C) an aqueous medium consisting essentially of water,
wherein the water-soluble polymer has an acid number of at least 130 and a weight average molecular weight of at least 5,000 and up to and including 20,000, and comprises: (a) at least 55 mol % and up to and including 80 mol % of recurring units derived from one or more ethylenically unsaturated polymerizable monomers selected from the group consisting of substituted or unsubstituted styrenes, (meth)acrylates, and combinations thereof, each (meth)acrylate comprising either a pendant phenyl group or an alkyl ester group having 12 to 20 carbon atoms; and (b) at least 20 mol % and up to and including 35 mol % of recurring units comprising one or more carboxylic acid groups, all recurring unit amounts being based on the total recurring units in the water-soluble polymer.
2. The aqueous particle-free inkjet ink composition of claim 1 , wherein the one or more water-soluble dye colorants are one or more red dyes, green dyes, blue dyes, yellow dyes, orange dyes, magenta dyes, cyan dyes, or a blend of two or more of such dyes.
3. The aqueous particle-free inkjet ink composition of claim 1 , wherein the one or more water-soluble dye colorants are one or more acid red dyes, food red dyes, direct red dyes, food yellow dyes, acid yellow dyes, direct yellow dyes, food blue dyes, acid blue dyes, direct blue dyes, acid orange dyes, or a blend of two or more of such dyes.
4. The aqueous particle-free inkjet ink composition of claim 3 , further comprising one or more water-soluble black dyes in a total amount of less than 0.1 weight %, based on the total weight of the aqueous particle-free inkjet ink composition.
5. The aqueous particle-free inkjet ink composition of claim 1 , wherein the one or more water-soluble dye colorants are present in a total amount of at least 4 weight % and up to and including 8 weight %, based on the total weight of the aqueous particle-free inkjet ink composition.
6. The aqueous particle-free inkjet ink composition of claim 1 , wherein at least 98 weight % of the aqueous medium consists of water.
7. The aqueous particle-free inkjet ink composition of claim 1 , wherein the water-soluble polymer has an acid number of at least 130 and up to and including 240 and a weight average molecular weight of at least 5,000 and up to and including 15,000, and comprises: (a) at least 55 mol % and up to and including 80 mol % of recurring units derived from one or more ethylenically unsaturated polymerizable monomers selected from the group consisting of substituted or unsubstituted styrenes, (meth)acrylates, and combinations thereof, each (meth)acrylate comprising either a pendant phenyl group or an alkyl ester group having 12 to 18 carbon atoms; and (b) at least 20 mol % and up to and including 35 mol % of recurring units derived from one or more of acrylic acid, methacrylic acid, crotonic acid, tiglic acid, 4-vinylbenzoic acid, maleic acid, fumaric acid, citaconic acid, and methylmaleic acid, all recurring unit amounts being based on the total recurring units in the water-soluble polymer.
8. The aqueous particle-free inkjet ink composition of claim 7 , wherein the water-soluble polymer comprises: (a) at least 55 mol % and up to and including 80 mol % of recurring units derived from one or more ethylenically unsaturated polymerizable monomers selected from benzyl (meth)acrylates, a substituted or unsubstituted styrene, and a combination thereof; and (b) at least 20 mol % and up to and including 35 mol % of recurring units derived from (meth)acrylic acid, all recurring unit amounts being based on the total recurring units in the water-soluble polymer.
9. The aqueous particle-free inkjet ink composition of claim 1 , wherein the water-soluble polymer is present in the aqueous particle-free inkjet ink composition in an amount of at least 1.5 weight % and up to and including 3 weight %, and the one or more water-soluble dye colorants are present in a total amount of at least 4 weight % and up to and including 8 weight %, all amounts being based on the total weight of the aqueous particle-free inkjet ink composition.
10. The aqueous particle-free inkjet ink composition of claim 1 , wherein the water-soluble polymer is one or more of Polymers 1 through 9 below:
Polymer 1: poly(benzyl methacrylate-co-stearyl methacrylate-co-methacrylic acid) (35:30:35 weight ratio), neutralized with potassium hydroxide;
Polymer 2: poly(benzyl methacrylate-co-stearyl methacrylate-co-methacrylic acid) (35:30:35 weight ratio), neutralized with dimethylethanolamine;
Polymer 3: poly(styrene-co-α-methyl styrene-co-acrylic acid-co-ethoxyethoxyethyl acrylate) (52:7:29:12 weight ratio), neutralized with potassium hydroxide;
Polymer 4: poly(styrene-co-methacrylic acid) (64:36 weight ratio), neutralized with dimethylethanolamine;
Polymer 5: poly(lauryl methacrylate-co-methacrylic acid) (67:33 weight ratio), neutralized with dimethylethanolamine;
Polymer 6: poly(benzyl methacrylate-co-methacrylic acid) (67:33 weight ratio), neutralized with potassium hydroxide;
Polymer 7: poly(benzyl methacrylate-co-stearyl methacrylate-co-methacrylic acid) (63.5:15:21.5 weight ratio), neutralized with potassium hydroxide;
Polymer 8: poly(benzyl methacrylate-co-styrene-co-methacrylic acid) (30:45:25 weight ratio), neutralized with dimethylethanol amine; and
Polymer 9: poly(benzyl methacrylate-co-methacrylic acid) (77:23 weight ratio), neutralized with potassium hydroxide.
11. The aqueous particle-free inkjet ink composition of claim 10 , wherein one or more water-soluble dye colorants comprise one or more of a blue dye identified as CAS 90295-11-7, a yellow dye identified as CAS 72927-70-9, or a red dye identified as CAS 18472-87-2.
12. The aqueous particle-free inkjet ink composition of claim 11 , further comprising one or more water-soluble black dyes in a total amount of less than 0.1 weight %.