Thermal transfer printing

Patent metadata

Field	Value
Publication number	US-12397573-B2
Application number	US-202217673179-A
Country	US
Kind code	B2
Filing date	Feb 16, 2022
Priority date	Nov 30, 2016
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A printing assembly for thermal transfer printing is disclosed. The assembly comprises at least one first printing system comprising a transfer member having an imaging surface on the front side, a coating station at which a monolayer of thermoplastic particles is applied to the imaging surface, an imaging station at which electromagnetic radiation (EM) is applied, optionally via the rear side of the transfer member, to selected regions of the imaging surface to render the particles coating the selected regions tacky, a transfer station at which only the regions of the particles coating that have been rendered tacky are transferred to a substrate to form an adhesive image; and at least one more downstream printing system. The transfer member includes on its front side an EM radiation absorbing layer, the imaging surface being formed on, or as part of, the absorbing layer, and on its rear side a body which can optionally be transparent to EM radiation.

First claim

The invention claimed is:

1. A printing assembly comprising:
A] a first printing system operational to effect printing onto a surface of a substrate by thermal transfer, the first printing system comprising:
a) a transfer member having opposite front and rear sides with an imaging surface on the front side;
b) a coating station at which a monolayer of first particles made of, or coated with, a thermoplastic polymer is applied to the imaging surface, or at least a segment thereof, the transfer member and the coating station being operationally in relative movement;
c) an imaging station at which energy in the form of electromagnetic (EM) radiation is applied to selected regions of the imaging surface to render first particles coating the selected regions tacky; and
d) a transfer station at which the imaging surface of the transfer member and the surface of the substrate, or respective segments thereof, are operationally pressed against each other to cause the first particles that have been rendered tacky to transfer to the surface of the substrate whereby an adhesive image is formed on the substrate;
wherein the transfer member is formed of a body on the rear side and an EM radiation absorbing layer made of an elastomeric silicone on the front side of the transfer member adjoining the body, the imaging surface being formed on, or as part of, the radiation absorbing layer; and
B] a second printing system configured to apply second particles;
the printing assembly further comprising a heating station at which at least a part of the adhesive image on the substrate is heated so that it is tacky at least during the application of the second particles at the second printing system, to cause second particles to adhere to the at least heated part of the adhesive image.

2. The printing assembly of claim 1 , wherein the EM radiation applied to the selected regions of the imaging surface is applied to the front side of the transfer member.

3. The printing assembly of claim 1 , wherein the EM radiation applied to the selected regions of the imaging surface is applied via the rear side of the transfer member, the body of the transfer member being transparent to the EM radiation.

4. The printing assembly of claim 3 , further comprising a lubrication system configured to controllably release a lubricant to the rear side of the transfer member of the first printing system.

5. The printing assembly of claim 3 , wherein the transfer station of the first printing system comprises an impression cylinder positioned facing the front side of the transfer member so as to define a nip at which at least a segment of the imaging surface of the transfer member and at least a segment of the surface of the substrate are pressed against each other, and wherein the imaging station is configured and aligned to apply radiation to the rear side of the transfer member at and/or adjacent the nip, so that rendering of the first particles coating the selected regions tacky, and pressing of the imaging surface of the transfer member and the surface of the substrate, or respective segments thereof, against each other, occur substantially concurrently.

6. The printing assembly of claim 5 , wherein the imaging station further comprises a transparent member facing the rear side of the transfer member at the nip, the transfer member sliding during operation between the transparent member and the impression cylinder, the applied EM radiation passing through the transparent member.

7. The printing assembly of claim 6 , wherein the transparent member is one of: a) a compressible transparent member; b) a non-compressible transparent member, the first printing system further comprising a pressure applicator having a compressible segment in contact with the rear side of the transfer member adjacently to the nip; c) a transparent member including a surface disposed to contact at least in a portion thereof, a portion of the rear side of the transfer member, the surface having one or two rounded edges to facilitate for a lubricant at least one of entry in-between the surface and the rear side and exit from in-between the surface and the rear side; and d) a transparent member including a surface disposed to contact at least in a portion thereof the rear side of the transfer member, the surface having one or more grooves for directing traversal of a lubricant between the surface and the rear side.

8. The printing assembly of claim 1 , wherein the coating station is configured to apply a fresh monolayer coating of first particles to the selected regions from which the first particles were previously transferred to the substrate surface to form the adhesive image, to render the imaging surface uniformly coated with a monolayer of first particles.

9. The printing assembly of claim 1 , wherein the imaging surface is the outer surface of a drum or of an endless transfer member.

10. The printing assembly of claim 1 , wherein the second printing system comprises:
a) a second transfer member having opposite front and rear sides with a particle receiving surface on the front side;
b) a second coating station at which a monolayer of second particles is applied to the particle receiving surface, the second transfer member and the second coating station being operationally in relative movement; and
c) a second transfer station at which the particle receiving surface of the second transfer member and the surface of the substrate, or respective segments thereof, are operationally pressed against each other to cause transfer of the second particles to at least a part of the adhesive image formed on the substrate at the first printing system.

11. The printing assembly of claim 10 , wherein the second transfer station of the second printing system comprises a second impression cylinder facing the front side of the second transfer member, the second impression cylinder being positioned so as to define a second nip at which the particle receiving surface of the second transfer member and the surface of the substrate, or respective segments thereof, are pressed against each other, the second impression cylinder being same or different than the impression cylinder of the first printing system.

12. The printing assembly of claim 11 , wherein the heating station is disposed at or adjacent to the second nip, the heat being applied to at least a part of the adhesive image at and/or adjacent the second nip, so that heating the adhesive image and pressing of the particle receiving surface of the second transfer member and the surface of the substrate, or respective segments thereof, against each other, occur substantially concurrently.

13. The printing assembly of claim 11 , wherein the particle receiving surface of the second transfer member is the outer surface of a) a second drum and the second nip is between the second drum and the second impression cylinder, or b) an endless second transfer member and the second nip is between a pressure roller facing the rear side of the endless second transfer member and the second impression cylinder.

14. The printing assembly of claim 13 , wherein the second impression cylinder is different than the impression cylinder of the transfer station of the first printing system, and at least one of the drum, pressure roller and second impression cylinder is capable of heating so as to constitute at least a part of the heating station.

15. The printing assembly of claim 13 , wherein at least one of the drum, pressure roller, impression cylinder and second impression cylinder further includes a compressible layer on its outer surface.

16. The printing

Assignees

• Landa Labs 2012 Ltd

Inventors

• Landa Benzion
• Abramovich Sagi
• Haviv Amit
• Aknin Ofer
• Valdman Yaakov
• Nagler Michael

Classifications

• G03G15/321 Primary

  by charge transfer onto the recording material in accordance with the image · CPC title

• G03G15/342

  by forming a uniform powder layer and then removing the non-image areas · CPC title

• B41M5/03

  by pressure · CPC title

• B41J2/447

  using arrays of radiation sources (B41J2/475 takes precedence) · CPC title

• B41J2/45

  using light-emitting diode {[LED] or laser} arrays · CPC title