Printing ink for use on flexible films

Abstract

A low viscosity printing ink composition, based on acrylic terminated urethanes, is made which has a rapid curing rate and forms a cured impression that has a good adherence and flexibility. The ink can be used on flexible films, such as sausage casings, without cracking or bleeding.

What is claimed: 
     
       1. An ultraviolet light curable ink composition which comprises; (i) a first urethane comprising a polyol urethane which is the reaction product of about one equivalent of an isocyanate containing intermediate, the isocyanate intermediate being the reaction product of about one equivalent of a monomeric diol and about two equivalents of an organic polyisocyanate, and about one equivalent oF a monomeric olefinically unsaturated compound containing exactly one active hydrogen, and   (ii) a second urethane comprising an acrylate-capped polycaprolactone which is the reaction product of a caprolactone polyol, a substituted or unsubstituted isocyanate, and an acrylyl compound, and defined by the formula; ##STR9##  where Z is hydrogen or methyl; Q is the residue of the caprolactone polyol, R is a linear or branched divalent alkylene having from 2 to about 5 carbon atoms; G is a linear or branched alkylene having from 1 to about 10 carbon atoms, or arylene, alkarylene and aralkylene having from 6 to about 12 carbon atoms, cycloalkylene having from 5 to about 10 carbon atoms, or bicycloalkylene having from 7 to about 15 carbon atoms; and x is an integer having a value from 1 to 4;   (iii) an ultraviolet photoinitiator in an amount sufficient to cure the ink composition when exposed to ultraviolet light, and   (iv) a pigment; wherein the first urethane and the second urethane are present in an amount such that the weight ratio of the first urethane to the second urethane is from about 2:5 to about 3:2.   
     
     
       2. The composition of claim 1 wherein the weight ratio of the first urethane to the second urethane is from about 3:5 and about 5:5. 
     
     
       3. The composition of claim 1 comprising additionally a reactive diluent monomer. 
     
     
       4. The composition of claim 3 wherein the reactive diluent monomer is glycidyl methacrylate or N-vinyl-2-pyrrolidone. 
     
     
       5. The composition of claim 1 wherein the monomeric olefinically unsaturated compound in (i) is an acrylate or methacrylate. 
     
     
       6. The composition of claim 1 wherein the monomeric olefinically unsaturated compound is acrylic acid, cinnamic acid, methacrylic acid, a hydroxyalkyl acrylate, a hydroxyalkyl methacrylate, cinnamyl alcohol, allyl alcohol, diacetone acrylamide or an unsaturated compound containing secondary amino or amido groups. 
     
     
       7. the composition of claim 1 wherein the polyisocyanate in (i) is a diisocyanate. 
     
     
       8. The composition of claim 1 wherein the polyol in (i) is a triol. 
     
     
       9. the composition of claim 1 wherein Z is methyl. 
     
     
       10. The composition of claim 1 wherein Z is hydrogen. 
     
     
       11. The composition of claim 1 wherein x is 2. 
     
     
       12. The composition of claim 1 wherein G is the polyvalent residue remaining after reaction of isophorone diisocyanate with the caprolactone polyol and acrylyl compound. 
     
     
       13. The composition of claim 1 wherein G is the polyvalent residue remaining after reaction of tetramethylene diisocyanate with the caprolactone polyol and acrylyl compound. 
     
     
       14. The composition of claim 1 wherein R is a linear alkylene having 2 or 3 carbon atoms. 
     
     
       15. The composition of claim 1 wherein the caprolactone polyol is the reaction product of a caprolactone having the structure; ##STR10## and a dihydroxyl compound. 
     
     
       16. The composition of claim 15 wherein the dihydroxyl compound is ethylene glycol or diethylene glycol. 
     
     
       17. The composition of claim 15 wherein the caprolactone is epsilon-caprolactone. 
     
     
       18. The composition of claim 1 wherein the combined amounts of the first urethane and the second urethane are from about 20 to about 80 weight percent, the photoinitiator is present in an amount from about 1 to about 10 weight percent, and the pigment is present in an amount greater than 0 to about 70 weight percent, based on the total weight of the composition. 
     
     
       19. The composition of claim 1 wherein the combined amounts of the first urethane and the second urethane are from about 50 to about 70 weight percent, the photoinitiator is present in an amount rom about 3 to about 7 weight percent, and the pigment is present in an amount from about 10 to about 50 weight percent, based on the total weight of the composition. 
     
     
       20. The composition of claim 18 wherein a reactive diluent is present in an amount from about 2 to about 30 weight percent, based on the total weight of the composition. 
     
     
       21. The composition of claim 19 wherein a reactive diluent is present in an amount from about 5 to about 20 weight percent, based on the total weight of the composition. 
     
     
       22. A process for the application of ink impressions upon a substrate comprising; providing an ultraviolet curable ink as defined in claim 1, applying the ultraviolet curable ink composition upon a substrate to form a printed impression upon the substrate, and exposing the printed impression upon the substrate to cure said impression to tack-free state. 
     
     
       23. A cured ink film upon a substrate which comprises the reaction product of an ultraviolet light curable ink which comprises; (i) a first urethane comprising a polyol urethane which is the reaction product of about one equivalent of an isocyanate containing intermediate, the isocyanate intermediate being the reaction product of about one equivalent of a monomeric diol and about two equivalents of an organic polyisocyanate, and about one equivalent of a monomeric olefinically unsaturated compound containing exactly one active hydrogen, and   (ii) a second urethane comprising an acrylate-capped polycaprolactone which is the reaction product of a caprolactone polyol, a substituted or unsubstituted isocyanate, and a acrylyl compound, and defined by the formula; ##STR11##  where Z is hydrogen or methyl; Q is the residue of the caprolactone polyol, R is the linear or branched divalent alkylene having from 2 to about 5 carbon atoms; G is a linear or branched alkylene having from 1 to 10 carbon atoms, or arylene, alkarylene and aralkylene having from 6 to about 12 carbon atoms, cycloalkylene having from 5 to about 10 carbon atoms, or bicycloalkylene having from 7 to about 15 carbon atoms; and x is an integer having a value from 1 to 4;   (iii) an ultraviolet photoinitiator in the amount sufficient to cure the ink composition when exposed to ultraviolet light, and   (v) a pigment; wherein the first urethane and the second urethane are present in an amount such that the weight ratio of the first urethane to the second urethane is from about 2:5 to about 3:2.     
     
     
       24. The film of claim 23 wherein the weight ratio of the first urethane to the second urethane is from about 3:5 about about 5:5. 
     
     
       25. The film of claim 23 comprising additionally a reactive diluent monomer. 
     
     
       26. The film of claim 25 wherein the reactive diluent monomer is glycidyl methacrylate or N-vinyl-2-pyrrolidone. 
     
     
       27. The film of claim 23 wherein the monomeric olefinically unsaturated compound in (i) is an acrylate or methacrylate. 
     
     
       28. The film of claim 23 wherein the monomeric olefinically unsaturated compound is acrylic acid, cinnamic acid, methacrylic acid, a hydroxyalkyl acrylate, a hydroxyalkyl methacrylate, cinnamyl alcohol, allyl alcohol, diacetone acrylamide or an unsaturated compound containing secondary amino or amido groups. 
     
     
       29. The film of claim 23 wherein the polyisocyanate in (i) is a diisocyanate. 
     
     
       30. The film of claim 23 wherein the polyol in (i) is a triol. 
     
     
       31. The film of claim 23 wherein Z is methyl. 
     
     
       32. The film of claim 23 wherein Z is hydrogen. 
     
     
       33. The film of claim 23 wherein x is 2. 
     
     
       34. The film of claim 23 wherein G is the polyvalent residue remaining after reaction of isophorone diisocyanate with the caprolactone polyol and acrylyl compound. 
     
     
       35. The film of claim 23 wherein G is the polyvalent residue remaining after reaction of tetramethylene diisocyanate with the caprolactone polyol and acrylyl compound. 
     
     
       36. The film of claim 23 wherein R is a linear alkylene having 2 or 3 carbon atoms. 
     
     
       37. The film of claim 23 wherein the caprolactone polyol is the reaction product of a caprolactone having the structure ##STR12## and a dihydroxyl compound. 
     
     
       38. The film of claim 37 wherein the dihydroxyl compound is ethylene glycol or diethylene glycol. 
     
     
       39. The film of claim 37 wherein the caprolactone is epsilon-caprolactone. 
     
     
       40. The film of claim 23 wherein the substrate comprises regenerated cellulose, polyethylene, ethylene vinyl acetate, polyvinylidene chloride, or polyvinyl chloride. 
     
     
       41. The film of claim 40 wherein the film comprises regenerated cellulose. 
     
     
       42. The film of claim 40 wherein the substrate is a sausage casing. 
     
     
       43. An ultraviolet light curable ink which comprises: (i) a first urethane which comprises the reaction product of an acrylated expoxidized drying oil and and organic isocyanate, and   (ii) a second urethane comprising an acrylate-capped polycaprolactone which is the reaction product of a caprolactone polyol, a substituted or unsubstituted isocyanate, and a acrylyl compound, and defined by the formula: ##STR13##  where Z is hydrogen or methyl; Q is the residue of the caprolactone polyol, R is a linear or branched divalent alkylene having from 2 to about 5 carbon atoms; G is a linear or branched alkylene having from 1 to about 10 carbon atoms, or arylene, alkarylene and aralkylene having from 6 to about 12 carbon atoms, cycloalkylene having from 5 to about 10 carbon atoms, or bicycloalkylene having 7 to about 15 carbon atoms; and x is an integer having a value from 1 to 4;   (iii) an ultraviolet photoinitiator in an amount sufficient to cure the ink composition when exposed to ultraviolet light, and   (iv) a pigment; wherein the first urethane and the second urethane are present in an amount such as that the weight ratio of the first urethane to the second urethane is from about 2:5 to about 3:2.     
     
     
       44. The composition of claim 43 wherein the first urethane comprises an acrylated epoxidized drying-oil urethane having in the molecule the group: ##STR14## wherein X is hydrogen or methyl, the acrylated epoxidized drying-oil urethane being the reaction product of epoxidized drying-oil reacted with acrylic or methacrylic and an organic isocyanate. 
     
     
       45. The composition of claim 43 wherein the acrylated epoxidized drying oil is the reaction product of epoxidized soybean oil and pentaerythritrol acrylate. 
     
     
       46. The composition of claim 45 wherein the pentaerthritrol acrylate has an average functionality of between about 3.1 and about 3.3.