US 12,215,242 B2
UV-VIS radiation curable security inks for producing dichroic security features
Hervé Pittet, Chatel-St-Denis (CH); Marlyse Demartin Maeder, La Sarraz (CH); Patrick Veya, Aclens (CH); Nikolay Grigorenko, Möhlin (CH); and Andre Oswald, Rheinfelden (DE)
Assigned to SICPA HOLDING SA, Prilly (CH)
Appl. No. 18/252,452
Filed by SICPA HOLDING SA, Prilly (CH)
PCT Filed Nov. 9, 2021, PCT No. PCT/EP2021/081156
§ 371(c)(1), (2) Date May 10, 2023,
PCT Pub. No. WO2022/101225, PCT Pub. Date May 19, 2022.
Claims priority of application No. 20206794 (EP), filed on Nov. 10, 2020.
Prior Publication US 2024/0018378 A1, Jan. 18, 2024
Int. Cl. C09D 11/50 (2014.01); B41M 3/14 (2006.01); B42D 25/378 (2014.01); C08K 3/08 (2006.01); C08K 7/00 (2006.01); C08K 9/04 (2006.01); C09D 11/03 (2014.01); C09D 11/037 (2014.01); C09D 11/101 (2014.01); C09D 11/102 (2014.01); C09D 11/106 (2014.01)
CPC C09D 11/50 (2013.01) [B41M 3/14 (2013.01); B42D 25/378 (2014.10); C09D 11/03 (2013.01); C09D 11/037 (2013.01); C09D 11/101 (2013.01); C09D 11/102 (2013.01); C09D 11/106 (2013.01); C08K 2003/0806 (2013.01); C08K 7/00 (2013.01); C08K 9/04 (2013.01); C08K 2201/003 (2013.01); C08K 2201/011 (2013.01)] 15 Claims
 
1. A UV-Vis radiation curable security ink for producing a security feature exhibiting a blue color upon viewing in transmitted light and a metallic yellow color upon viewing in incident light, wherein said ink comprises:
a) from about 7.5 wt-% to about 20 wt-% of silver nanoplatelets having a mean diameter in the range of 50 to 150 nm with a standard deviation of less than 60%, a mean thickness in the range of 5 to 30 nm with a standard deviation of less than 50%, and a mean aspect ratio higher than 2.0, wherein the mean diameter is determined by transmission electron microscopy and the mean thickness is determined by transmission electron microscopy, and
wherein the silver nanoplatelets bear a surface stabilizing agent of general formula (I)

OG Complex Work Unit Chemistry
wherein
the residue RA is a C2-C4alkyl group substituted with a hydroxy group;
the residue RB is selected from a C1-C4 alkyl group, and a C2-C4alkyl group substituted with a hydroxy group; and
Cat+ is an ammonium cation of general formula +NH2RCRD,
wherein the residue RC is a C2-C4alkyl group substituted with a hydroxy group; and
the residue RD is selected from a C1-C4alkyl group, and a C2-C4alkyl group substituted with a hydroxy group;
b) from about 45 wt-% to about 80 wt-% of either a cycloaliphatic epoxide, or a mixture of a cycloaliphatic epoxide and one or more UV-Vis radiation curable compounds;
c) one or more cationic photoinitiators;
d) a perfluoropolyether surfactant functionalized with one or more functional groups selected from the group consisting of: hydroxyl, acrylate, methacrylate, and trialkoxysilyl;
e) from about 3 wt-% to about 12 wt-% of a polyvinyl chloride copolymer containing at least 60 wt-% of vinyl chloride; and optionally
f) up to about 25 wt-% of an organic solvent;
the weight percents being based on the total weight of the UV-Vis radiation curable security ink.