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

Patent metadata

Field	Value
Publication number	US-12090776-B2
Application number	US-202017772730-A
Country	US
Kind code	B2
Filing date	Oct 23, 2020
Priority date	Oct 28, 2019
Publication date	Sep 17, 2024
Grant date	Sep 17, 2024

Abstract

The present invention relates to the field of magnetic assemblies and processes for producing optical effect layers (OELs) comprising magnetically oriented non-spherical magnetic or magnetizable pigment particles on a substrate. In particular, the present invention relates to magnetic assemblies 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. A magnetic assembly for producing an optical effect layer on a substrate, said magnetic assembly being configured for receiving the substrate in an orientation at least partially parallel to a first plane and further comprising:
a) a first magnetic-field generating device comprising at least four first dipole magnets having North poles pointing in a same direction and having magnetic axes oriented to be substantially parallel to the first plane, said first dipole magnets being spaced apart from each other,
wherein each of the first dipole magnets is arranged on an intersection of at least two substantially parallel straight lines straight lines α i (i=1, 2, . . . ) and at least two substantially parallel straight lines β j (j=1, 2, . . . ), the straight lines α i and β j forming a grid,
wherein at least two first dipole magnets are disposed on one of the straight lines α i and at least two other first dipole magnets are disposed on another one of the straight lines α i ,
wherein the magnetic axes of the first dipole magnets are oriented substantially parallel to the substantially parallel straight lines α i , and
wherein the first dipole magnets of said first magnetic-field generating device are partially or fully embedded in a first supporting matrix; and

b) a second magnetic-field generating device comprising one or more second dipole magnets having magnetic axes oriented to be substantially parallel to the first plane and wherein the one or more second dipole magnets are partially or fully embedded in a second supporting matrix;
wherein the second magnetic-field generating device is disposed below the first magnetic-field generating device, and
wherein each straight line α i and a vector sum H of the magnetic axes of the one or more second dipole magnets are substantially non-parallel and substantially non-perpendicular with respect to each other.

2. The magnetic assembly according to claim 1 , wherein each straight line α i and the vector sum H of the magnetic axes of the one or more second dipole magnets form an angle γ in the range from about 20° to about 70° or in the range from about 110° to about 160° or in the range from about 200° to about 250°, or in the range from about 290° to about 340°.

3. The magnetic assembly according to claim 1 , further comprising one or more third dipole magnets partially or fully embedded in the first supporting matrix, wherein said one or more third bar dipole magnets have magnetic axes oriented to be substantially parallel to the substrate surface and said third dipole magnets have North poles pointing in a different direction than the direction of the North poles of the first dipole magnets.

4. The magnetic assembly according to claim 1 , wherein the first magnetic-field generating device comprises at least nine first dipole magnets and the grid comprises at least three of the substantially parallel straight lines α i and at least three of the substantially parallel straight lines B φ , wherein at least three first dipole magnets are disposed on one of the straight lines α i , at least three first dipole magnets are disposed on another one of the straight lines α i and at least three further first dipole magnets are disposed on a further other one of the straight lines α i .

5. The magnetic assembly according to claim 1 , wherein, on each straight line α i and/or each straight line β j , neighboring first dipole magnets are separated from each other by a same distance.

6. The magnetic assembly according to claim 1 , wherein the second magnetic-field generating device comprises two or more second dipole magnets, each of said two or more second dipole magnets having magnetic axis oriented to be substantially parallel to the first plane.

7. The magnetic assembly according to claim 6 , wherein the second magnetic-field generating device comprises two second dipole magnets and wherein one of said two second dipole magnets is disposed on top of the other one of the second dipole magnets and wherein the two second dipole magnets have North poles pointing in different directions.

8. A printing apparatus comprising a rotating magnetic cylinder or a flatbed printing unit, the rotating magnetic cylinder or the flatbed printing unit comprising at least one magnetic assembly configured to receiving a substrate in an orientation at least partially parallel to a first plane, comprising:
a first magnetic-field generating device comprising at least four first dipole magnets having North poles pointing in a same direction and having magnetic axes oriented to be substantially parallel to the first plane, said first dipole magnets being spaced apart from each other,
wherein each of the first dipole magnets is arranged on an intersection of at least two substantially parallel straight lines α i (i=1, 2, . . . ) and at least two substantially parallel straight lines β j (j=1, 2, . . . ), the straight lines α i and β j forming a grid, wherein at least two first dipole magnets are disposed on one of the straight lines ai and at least two other first dipole magnets are disposed on another one of the straight lines α i , wherein the magnetic axes of the first dipole magnets are oriented substantially parallel to the substantially parallel straight lines α i , and wherein the first dipole magnets of said first magnetic-field generating device are partially or fully embedded in a first supporting matrix; and
a second magnetic-field generating device comprising one or more second dipole magnets having magnetic axes oriented to be substantially parallel to the first plane and wherein the one or more second dipole magnets are partially or fully embedded in a second supporting matrix;
wherein the second magnetic-field generating device is disposed below the first magnetic-field generating device, and wherein each straight line α i and a vector sum H of the magnetic axes of the one or more second dipole magnets are substantially non-parallel and substantially non-perpendicular with respect to each other.

9. A process for producing an optical effect layer on a substrate comprising the steps of:
i) applying on a substrate surface a radiation curable coating composition comprising non-spherical magnetic or magnetizable pigment particles, said radiation curable coating composition being in a first state so as to form a coating layer;
ii) exposing the radiation curable coating composition to a magnetic field of a static magnetic assembly so as to orient at least a part of the non-spherical magnetic or magnetizable pigment particles, said magnetic assembly being configured for receiving the substrate in an orientation at least partially parallel to a first plane, comprising:
a first magnetic-field generating device comprising at least four first dipole magnets having North poles pointing in a same direction and having magnetic axes oriented to be substantially parallel to the first plane, said first dipole magnets being spaced apart from each other,
wherein each of the first dipole magnets is arranged on an intersection of at least two substantially parallel straight lines α i (i=1, 2, . . . ) and at least two substantially parallel straight lines β j (j=1, 2, . . . ), the straight lines α i and β j forming a grid,
wherein at least two first dipole magnets are disposed on one of the straight lines α i and at least two other first dipole magnets are disposed on another one of the straight lines α i ,
wherein the magnetic axes of the first dipole magnets are oriented substantially parallel to the substantially parallel straight lines α i , and
wherein the first dipole magnets of said first magnetic-field generating device are partially or fully embedded in a first supporting matrix;

Assignees

• Sicpa Holding Sa

Inventors

• Loginov Evgeny
• Schmid Mathieu
• Despland Claude-Alain

Classifications

• G02F1/0081

  Electric or magnetic properties · CPC title

• B05D3/207

  post-treatment by magnetic fields · CPC title

• G09F3/03

  of security seals {(means for indicating unauthorised opening of container closures B65D, e.g. B65D27/30, B65D55/02; theft deterrent tags E05B73/0017)} · CPC title

• B42D25/369 Primary

  Magnetised or magnetisable materials · CPC title

• B42D25/355 Primary

  Security threads · CPC title