Overcoat composition for image recording materials
The invention relates to an overcoat composition for an imaged image-recording element, the overcoat composition comprising an aqueous carrier, an optional humectant, an optional surfactant, and 0.05 to 20 weight percent, based on the total weight of the overcoat composition, of an addition polymer having an acid number greater than about 110. The invention also relates to a method of making an imaged image recording element having a transparent overcoat, which method comprises forming an image on the image recording element and applying over the image an overcoat composition of the present invention. The overcoat compositions of the invention provide advantageous stain resistance.
1. An imaged inkjet recording element having a transparent substantially colorless overcoat over the image, wherein the overcoat is applied as an overcoat composition comprising an aqueous carrier, an optional humectant, an optional surfactant, and 0.05 to 20 weight percent, based on the total weight of the overcoat composition, of at least one water-soluble addition polymer having an acid number greater than about 110, wherein the at least one water-soluble addition polymer has been neutralized by an amount of base that is at least 30 mole percent based on the acid groups in the polymer.
2. The imaged inkjet recording element of claim 1 , wherein the overcoat comprises 0.05 to 20 weight percent, based on the total weight of the overcoat composition, of two or more water-soluble addition polymers, wherein the arithmetic mean of the acid numbers of all addition polymers in the overcoat composition is greater than 110.
3. The imaged inkjet recording element of claim 1 , wherein the acid number is between about 110 and about 300.
4. The imaged inkjet recording element of claim 1 , wherein the overcoat composition comprises a single water-soluble addition polymer that is the reaction product of mixture of vinyl or unsaturated monomers and which polymer has a hydrophilic group in a portion of the monomers, wherein the water-soluble addition polymer is not water soluble until neutralized by a base.
5. The imaged inkjet recording element of claim 1 , wherein the at least one water-soluble addition polymer is a styrene-acrylic acid polymer.
6. The imaged inkjet recording element of claim 1 , wherein the at least one water-soluble addition polymer is a styrene-acrylic polymer comprising a mixture of vinyl or unsaturated monomers, including at least one styrenic monomer and at least one acrylic monomer, at least one of which of the styrenic monomer or the acrylic monomer has an acid or acid-providing group, wherein the overcoat composition has been applied dropwise over the image.
7. The imaged inkjet recording element of claim 6 , wherein the acid or acid providing group is on the acrylic monomer.
8. The imaged inkjet recording element of claim 6 , wherein the at least one water-soluble addition polymer comprises at least one styrenic monomer selected from the group consisting of α-alkylstyrenes, trans-β-alkylstyrenes, alkylstyrenes, alkoxystyrenes, halogenated styrenes, and vinyl naphthalenes.
9. The imaged inkjet recording element of claim 8 , wherein the at least one water-soluble addition polymer comprises at least one styrenic monomer selected from the group consisting of styrene, α-methylstyrene, trans-β-methylstyrene, 3-methylstyrene, 4-methylstyrene, 3-ethyl styrene, 3-isopropyl styrene, 3-butyl styrene, 3-cyclohexyl styrene, 3,4-dimethyl styrene, 3-chlorostyrene, 3,4-dichloro styrene, 3,4,5-trichloro styrene, 3-bromo styrene, 3-iodo styrene, 3-fluoro styrene, 3-chloro-4-methyl styrene, benzyl styrene, vinyl naphthalene, divinylbenzene, methyl vinylbenzoate ester, vinylbenzoic acid, vinyl phenol, 3-methoxy styrene, 3,4-dimethoxy styrene, 3-methyl-4-methoxy styrene, acetoxystyrene, acetoxymethylstyrene, (t-butoxycarbonyloxy) styrene, and mixtures thereof, wherein the styrenic monomers may optionally be substituted with ionic functionalities selected from the group consisting of phosphate, sulfonate, and carboxylate.
10. The imaged inkjet recording element of claim 7 , wherein the at least one water-soluble addition polymer comprises at least one acrylic monomer selected from the group consisting of acrylic acid monomers and unsaturated anhydride and unsaturated imide monomers which may be completely or partially hydrolyzed after polymerization to form the corresponding carboxylic acid or amide functionality.
11. The imaged inkjet recording element of claim 10 , wherein the at least one water-soluble addition polymer comprises at least one acrylic monomer selected from the group consisting of acrylic acid, alkylacrylic acids, 3-alkylacrylic acids, 3-haloacrylic acids, maleic anhydride, methylmaleic anhydride, glutaconic anhydride, itaconic anhydride, citraconic anhydride, mesaconic anhydride, maleimide and N-methylmaleimide, and mono-ester and bis-ester derivatives of the aforementioned.
12. The imaged inkjet recording element of claim 11 , wherein the at least one water-soluble addition polymer comprises at least one acrylic monomer selected from the group consisting of crotonic acid, cinnamic acid, citraconic acid, sorbic acid, fumaric acid, methacrylic acid, ethacrylic acid, 3-methylacrylic acid, 3-chloroacrylic acid, and 3-chloromethacrylic acid.
13. The imaged inkjet recording element of claim 1 , wherein the at least one water-soluble addition polymer comprises at least one acrylate ester selected from the group consisting of alkyl acrylates, aryl acrylates, alkyloxyalkyl acrylates, alkyloxyaryl acrylates, hydroxyalkyl acrylates, hydroxyaryl acrylates, crotonic esters, cinnamic esters, citraconic esters, sorbic esters, and fumaric esters.
14. The imaged inkjet recording element of claim 1 , wherein the at least one water-soluble addition polymer comprises at least one styrene-acrylic polymer that comprises at least one acrylic monomer that is functionalized with a carboxylic acid group.
15. The imaged inkjet recording element of claim 1 , wherein the at least one water-soluble addition polymer in solution has been prepared by neutralization of the polymer using an inorganic base.
16. The imaged inkjet recording element of claim 1 , wherein the base is an alkali metal hydroxide or ammonia.
17. The imaged inkjet recording element of claim 1 , wherein the base is an inorganic base selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, and the amount of base used is at least about 70 mole % based on the acid groups in the at least one water-soluble addition polymer.
18. The imaged inkjet recording element of claim 1 , wherein the base is an organic base selected from the group consisting of ammonia, mono-, di- and trialkyl- or aryl amines; nitrogen-containing heterocycles; tetraalkyl- or aryl amines, and combinations thereof.
19. The imaged inkjet recording element of claim 1 , wherein the at least one water-soluble addition polymer has a weight average molecular weight range of from about 2000 to about 300,000.
20. The imaged inkjet recording element of claim 19 wherein the weight average molecular weight is from about 2,000 to about 100,000.