Assemblies and processes for producing optical effect layers comprising oriented non-spherical oblate magnetic or magnetizable pigment particles

Patent metadata

Field	Value
Publication number	US-11065906-B2
Application number	US-201816641942-A
Country	US
Kind code	B2
Filing date	Aug 23, 2018
Priority date	Aug 25, 2017
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

The present invention relates to the field of optical effect layers (OEL) comprising magnetically oriented non-spherical oblate magnetic or magnetizable pigment particles on a substrate, spinneable magnetic assemblies and processes for producing said optical effect layers (OEL). In particular, the present invention relates to spinneable magnetic assemblies and processes for producing said OELs as anti-counterfeit means on security documents or security articles or for decorative purposes.

First claim

The invention claimed is:

1. An optical effect layer (OEL) comprising a radiation cured coating composition comprising non-spherical oblate magnetic or magnetizable pigment particles, said non-spherical oblate magnetic or magnetizable pigment particles being oriented according to an orientation pattern,
wherein the orientation pattern is circularly symmetric around a center of rotation,
wherein the non-spherical oblate magnetic or magnetizable pigment particles at at least two, distinct locations x i along any selected diameter of the OEL have an average zenithal deflection angle φ′ at location x i and an average azimuth angle θ with respect to the selected diameter at the same location x i that satisfy the condition |(φ′ sin (θ)|≥10°,
and said optical effect layer providing an optical impression of at least one circularly moving spot or at least one spot having a tail section rotating around said center of rotation upon tilting said OEL.

2. The optical effect layer according to claim 1 , wherein at least a part of the plurality of non-spherical oblate magnetic or magnetizable particles is constituted by non-spherical oblate optically variable magnetic or magnetizable pigment particles.

3. The optical effect layer according to claim 2 , wherein the optically variable magnetic or magnetizable pigments are selected from the group consisting of magnetic thin-film interference pigments, magnetic cholesteric liquid crystal pigments and mixtures thereof.

4. The optical effect layer according to claim 1 , wherein the radiation cured coating composition is a UV-Vis radiation cured coating composition.

5. A security document or a decorative element or object comprising one or more optical effect layers (OELs) recited in claim 1 .

6. A printing apparatus for producing on a substrate the optical effect layer (OEL) recited in claim 1 , wherein the non-spherical oblate magnetic or magnetizable pigment particles are oriented with a magnetic field from at least one spinning magnetic assembly comprised in the apparatus, the spinning magnetic assembly having an axis of spinning, wherein a surface of the substrate provided with the OEL is substantially perpendicular to the axis of spinning of the magnet assembly, and comprising at least a) first magnetic-field generating device and b) a second magnetic-field generating device, wherein said first magnetic-field generating device and said second magnetic-field generating device have mutually skewed magnetic axes, wherein said first magnetic- field generating device has its magnetic axis substantially perpendicular to the axis of spinning and said second magnetic-field generating device has its magnetic axis substantially perpendicular to the axis of spinning and wherein a projection of the magnetic axis of the first magnetic-field generating device and a projection of the magnetic axis of the second magnetic-field generating device along the axis of spinning onto a plane perpendicular to the axis of spinning form an angle either in a range from about 5° to about 175° or in a range from about −5° to about −175°, and wherein
a) the first magnetic-field generating device comprises
a bar dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning, or
two or more bar dipole magnets, each of said two or more bar dipole magnets having its North-South magnetic axis substantially perpendicular to the axis of spinning and all of said two or more bar dipole magnets having a same magnetic field direction, or
a loop-shaped dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning, or
a disc-shaped dipole magnet being nested inside a loop-shaped dipole magnet, each of the disc-shaped dipole magnet and the loop-shaped dipole magnets having their North-South magnetic axis substantially perpendicular to the axis of spinning and having a same magnetic field direction, or
two or more nested loop-shaped dipole magnets, each of said two or more nested loop-shaped dipole magnets, having its North-South magnetic axis substantially perpendicular to the axis of spinning and all of said two or more nested ring-shaped magnets having a same magnetic field direction; and wherein

b) the second magnetic-field generating device comprises
a disc-shaped dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning, or
a loop-shaped dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning, or
a bar dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning.

7. The apparatus according to claim 6 ,
wherein the first magnetic-field generating device comprises a loop-shaped dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning and the second magnetic-field generating device (x 40 ) comprises a disc-shaped dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning; or
wherein the first magnetic-field generating device comprises a loop-shaped dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning and the second magnetic-field generating device (x 40 ) comprises a loop-shaped dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning; or
wherein the first magnetic-field generating device comprises a bar dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning and the second magnetic-field generating device comprises a disc-shaped dipole magnet having its North-South magnetic axis perpendicular to the axis of spinning; or
wherein the first magnetic-field generating device comprises two or more bar dipole magnets, each of said two or more bar dipole magnets having its North-South magnetic axis substantially perpendicular to the axis of spinning and all of said two or more bar dipole magnets having a same magnetic field direction and the second magnetic-field generating device comprises a disc-shaped dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning; or
wherein the first magnetic-field generating device comprises a disc-shaped dipole magnet being nested inside a loop-shaped dipole magnet, each of the disc-shaped dipole magnet and the loop-shaped dipole magnet having their North-South magnetic axis substantially perpendicular to the axis of spinning and having a same magnetic field direction and the second magnetic-field generating device comprises a disc-shaped dipole magnet having its North-South magnetic axis substantially perpendicular to the axis of spinning; or
wherein the first magnetic-field generating device comprises two or more nested ring-shaped magnets, each of said two or more nested ring-shaped magnets having its North-South magnetic axis substantially perpendicular to the axis of spinning and all of said two or more nested ring-shaped magnets having a same magnetic field direction and the second magnetic-field generating device comprises a disc-shaped dipole magnet having its North-South magnetic axis perpendicular to the axis of spinning.

8. The apparatus according to claim 7 , where the loop shaped dipole magnets are ring-shaped.

9. The apparatus according to claim 6 further comprising a rotating magnetic cylinder or a flatbed printing unit, wherein the at least one spinning magnetic assembly is comprised in the rotating magnetic cylinder or the flatbed printing unit.

10. The apparatus according to claim 6 , wherein the projection of the magnetic axis of the first magnetic-field generating device and the pr

Assignees

• Sicpa Holding Sa

Inventors

• Amerasinghe Cédric
• Mueller Edgar
• Loginov Evgeny
• Schmid Mathieu
• Despland Claude-Alain

Classifications

• B41M3/14

  Security printing {(securities B42D25/29)} · CPC title

• B41F19/005

  with means for applying metallic, conductive or chargeable material · CPC title

• B05D5/06

  to obtain multicolour or other optical effects (B05D5/02 takes precedence) · CPC title

• B05D3/065 Primary

  After-treatment · CPC title

• B42D25/387

  absorbing or reflecting ultraviolet light · CPC title