Ec primer coating for paper and paperboard

Abstract

Disclosed are energy curable primer compositions for use on uneven substrates such as paper or board to help create a non-porous, smooth, print-receptive surface for subsequent in-line or off-line application of metallic or special effect inks for generating a superior appearance such as a mirror-like metallic or other special effect for promotional or high-value packaging applications. Compositions suitable for low odor and low migration indirect contact food, tobacco, or pharmaceutical product packaging are also disclosed.

1 . A primer composition comprising:
 (a) an acrylic monomer comprising C—O—C and C═C functional groups; and   (b) an acrylic oligomer comprising C—O—C and C═C functional groups, wherein, said primer composition is energy curable and the calculated ratio of C—O—C to C═C functionality in the sum of the acrylic monomer and acrylic oligomer is greater than 1.6.   
     
     
         2 . The composition of  claim 1 , wherein the calculated ratio of C—O—C to C═C functionality in the sum of the acrylic monomer and acrylic oligomer is greater than 1.8. 
     
     
         3 . The primer composition of  claim 1  when cured and applied using a Flexiproofer with a 15 bcm anilox on Leneta N2A-3 chart has a dispersive surface energy of at least 37 mN/m; and yields an upper surface with gloss greater than 55 at 20° angle, and gloss greater than 83 at 60° angle. 
     
     
         4 . The primer composition of  claim 1  when cured and applied using a TMI Flexiproofer with a 15 bcm anilox onto a Leneta N2A-3 chart, and then overprinted with SC17604 acetate solvent-based vacuum metalized pigment silver ink, applied with a Meyer #3 bar, and dried, yields an upper surface with brilliance index of at least 80%. 
     
     
         5 . The primer composition of  claim 1 , wherein there is at least 50% reduction in coating viscosity when measured at 10sec −1  between 25° C. and 45° C. 
     
     
         6 . The primer composition of  claim 1  when cured exhibiting a total visible light reflectance greater than or equal to 60. 
     
     
         7 . The primer composition of  claim 1  having a static surface tension of up to 33 mN/m. 
     
     
         8 . The primer composition of  claim 1  exhibiting a 60° gloss reduction of less than 10 points and a 20° gloss reduction of less than 20 points when changing from 15 bcm to 5 bcm anilox. 
     
     
         9 . The primer composition of  claim 1  exhibiting a 60° gloss difference between the white coated area of the BYK Penopac 2817 chart compared with the white uncoated area of the chart of less than 2 at 15 bcm and less than 4 at 10 bcm. 
     
     
         10 . The primer composition of  claim 1  having a viscosity at 45° C. between 17 and 25 cPs. 
     
     
         11 . The primer composition of  claim 1 , wherein each of the acrylic monomer and acrylic oligomer has a molecular weight greater than 300 g/mole. 
     
     
         12 . The primer composition of  claim 1 , wherein there is at least 50% reduction in coating viscosity when measured at 10sec −1  between 25° C. and 45° C., and wherein said primer composition, when cured and applied using a Flexiproofer with a 15 bcm anilox on Leneta N2A-3 chart has a dispersive surface energy of at least 37 mN/m, yields an upper surface with gloss greater than 55 at 20° angle, and gloss greater than 83 at 60° angle. 
     
     
         13 . The primer composition of  claim 1 , wherein there is at least 50% reduction in coating viscosity when measured at 10sec −1  between 25° C. and 45° C., and wherein said primer composition, when cured and applied using a TMI Flexiproofer with a 15 bcm anilox onto a Leneta N2A-3 chart, and then overprinted with SC17604 acetate solvent-based vacuum metalized pigment silver ink, applied with a Meyer #3 bar, and dried, yields an upper surface with brilliance index of at least 80. 
     
     
         14 . A printed article comprising: the primer composition of  claim 1  a primer composition comprising:
 (a) an acrylic monomer comprising C—O—C and C═C functional groups; and 
 (b) an acrylic oligomer comprising C—O—C and C═C functional groups; 
 wherein the composition is essentially solvent-free; and 
 wherein, said primer composition is energy curable and the calculated ratio of C—O—C to C═C functionality in the sum of the acrylic monomer and acrylic oligomer is greater than 1.6, that when cured exhibits a total visible light reflectance greater than or equal to 60. 
 
     
     
         15 . The article of  claim 1  being used in packaging. 
     
     
         16 . A method of printing an energy curable primer composition comprising applying to a substrate the primer composition of  claim 1 . 
     
     
         17 . The method of  claim 16  in which the method of printing is flexo or gravure. 
     
     
         18 . A method for forming a brilliant metallic coated paper material comprising:
 (a) applying a layer of the primer composition of  claim 1  to a paper surface of the paper material;   (b) curing the layer of the primer to create an ink receptive interface layer;   (c) applying a reflective metallic ink including a plurality of reflective particles to at least a portion of the cured primer layer; and   (d) drying the metallic ink to form a reflective metallic ink layer on the cured primer.   
     
     
         19 . The method of  claim 18 , wherein said primer composition, when cured and applied using a Flexiproofer with a 15 bcm anilox on Leneta N2A-3 chart has a dispersive surface energy of at least 37 mN/m, yields an upper surface with gloss greater than 55 at 20° angle, and gloss greater than 83 at 60° angle. 
     
     
         20 . The method of  claim 18 , wherein said primer composition, when cured and applied using a TMI Flexiproofer with a 15 bcm anilox onto a Leneta N2A-3 chart, and then overprinted with SC17604 acetate solvent-based vacuum metalized pigment silver ink, applied with a Meyer #3 bar, and dried, yields an upper surface with brilliance index of at least 80%.