INTERMEDIATE TRANSFER MEMBER WITH PAPER-BASED LAYER

1 . An intermediate transfer member (ITM) for use in a printing system, the ITM comprising:

a. a silicone-based release layer having an upper surface for ink-reception, said upper-surface for ink-reception adapted to satisfy at least one of a first structural property and a second structural property, the first and second structural properties being defined below;

b. a paper-based layer which is impregnated with and/or coated with epoxy, said paper-based layer being disposed beneath the release layer including at least 50% or at least 60% or at least 80% paper fiber, the paper-based layer configured to contribute to ITM stiffness such that a ratio between (i) a spring constant in the longitudinal direction of the paper-based layer; and a (ii) a spring constant in the longitudinal direction of the ITM is at least 0.5 or at least 0.6 or at least 0.7 or at least 0.8;

c. a grip-layer disposed beneath the paper-based layer, wherein:

A. the paper-based layer has a black upper surface and/or the ITM includes comprising an additional electromagnetic-energy-absorbing layer above the paper layer and below the release layer, said energy-absorbing layer comprising black material;

B. according to the first structural property, a receding contact angle of a droplet of distilled water on said upper surface of said silicone-based release layer is at most 60°;

C. according to the second structural property, for a droplet of distilled water deposited on said upper surface of said silicone-based release layer, a 10 second dynamic contact angle (DCA) is at most 108°.

2 . The ITM of claim 1 wherein the paper-based layer is impregnated with the epoxy.

3 . The ITM of any preceding claim wherein the paper-based layer is coated with the epoxy.

4 . The ITM of any preceding claim wherein a ratio between (i) a spring constant in the longitudinal direction of the paper-based layer; and a (ii) a spring constant in the longitudinal direction of the ITM is at least 0.6 or at least 0.7 or at least 0.8.

5 . The ITM of any preceding claim wherein a ratio between (i) a longitudinal-direction tensile strength in the longitudinal direction of the paper-based layer; and a (ii) a longitudinal-direction tensile strength in the longitudinal direction of the ITM is at least 0.5 or at least 0.6 or at least 0.7.

6 . The ITM of any preceding claim wherein a ratio between (i) a longitudinal-direction tear-resistance in the longitudinal direction of the paper-based layer; and a (ii) a tear-resistance in the longitudinal direction of the ITM is at least 0.5 or at least 0.6 or at least 0.7.

7 . The ITM of any preceding claim wherein a presence of the epoxy in or on the paper-based layer contributes at least 20% or at least 30% or at least 40% or at least 50% to the tensile strength of the ITM in the longitudinal direction.

8 . The ITM of any preceding claim wherein a presence of the epoxy in or on the paper-based layer contributes at least 20% or at least 30% or at least 40% or at least 50% to the tear resistance of the ITM in the longitudinal direction.

9 . The ITM of any preceding claim wherein the grip-layer is electrically conductive.

10 . An intermediate transfer member (ITM) for use in a printing system, the ITM comprising:

a. a release layer having an upper surface for ink-reception; and

b. a paper-based layer disposed beneath the release layer and configured to contribute to ITM stiffness such that a ratio between (i) a spring constant in the longitudinal direction of the paper-based layer; and a (ii) a spring constant in the longitudinal direction of the ITM is at least 0.6, said paper-based layer including at least 50% or at least 60% or at least 80% paper fiber;

c. a fabric layer disposed beneath the paper-based layer and configured to contribute to ITM tear resistance such that a ratio between a tear-resistance of the fabric layer in the longitudinal direction and a tear resistance of the ITM in the longitudinal direction is at least 0.6, wherein:

i. an average surface roughness of an upper surface of the fabric layer in the ITM is at least 0.5 μm; and

ii. an average surface roughness of an upper surface of the paper-based layer is at most 0.2 μm.

11 . An intermediate transfer member (ITM) for use in a printing system, the ITM comprising:

a. a release layer having an upper surface for ink-reception; and

b. a paper-based layer disposed beneath the release layer and configured to contribute to ITM stiffness such that a ratio between (i) a spring constant in the longitudinal direction of the paper-based layer; and a (ii) a spring constant in the longitudinal direction of the ITM is at least 0.6, said paper-based layer including at least 50% or at least 60% or at least 80% paper fiber;

c. a fabric layer disposed beneath the paper-based layer and configured to contribute to ITM tensile strength such that a ratio between a tensile strength of the fabric layer in the longitudinal direction and a tensile strength of the ITM in the longitudinal direction is at least 0.6, wherein:

i. an average surface roughness of an upper surface of the fabric layer in the ITM is at least 0.5 μm; and

ii. an average surface roughness of an upper surface of the paper-based layer is at most 0.2 μm.

12 . The ITM of any one of claims 10-11 wherein the fabric layer is a glass-fabric layer.

13 . The ITM of any one of claims 10-12 wherein a ratio between a tear-resistance of the fabric layer in the longitudinal direction and a tear resistance of the ITM in the longitudinal direction is at least 0.8.

14 . The ITM of any one of claims 10-13 wherein a ratio between a tensile strength of the fabric layer in the longitudinal direction and a tensile strength of the ITM in the longitudinal direction is at least 0.8.

15 . The ITM of any one of claims 10-14 wherein a ratio between (i) a spring constant in the longitudinal direction of the paper-based layer; and a (ii) a spring constant in the longitudinal direction of the ITM is at least 0.8.

16 . The ITM of any one of claims 10-15 wherein a ratio between a surface roughness of the ITM upper surface and a surface roughness of an upper surface of the fabric layer is at most 0.1.

17 . The ITM of any preceding claim wherein a surface roughness of an upper surface of the ITM is at at most 0.5 μm or at most 0.25 μm or at most 0.15 μm or at most 0.1 μm after the upper surface of ITM is subjected to at least 1000 2+-second heating(120+° C.)/4+-second cooling (90−° C.) events.

18 . The ITM of any preceding claim wherein the ITM is characterized by an absence of any interior layer of the ITM whose direction-maximized CLTE value is at least 10*100 meter/(meter ° C.) or at least 15* 10 −6 meter/(meter ° C.) at least 20*10 −6 meter/(meter ° C.).

19 . The ITM of any preceding claim wherein the ITM lacks one or both of an interior plastic layer.

20 . The ITM of any preceding claim , wherein the ITM is formed by a flat elongate strip of which the ends are secured to one another at a seam to form a continuous loop.

21 . The ITM of any one of claims 1-9 wherein the electromagnetic-energy-absorbing layer above the paper layer and below the release layer is a layer of carbon-black-impregnated silicone.

22 . An intermediate transfer member (ITM) for use in a printing system, the ITM comprising:

a. a silicone-based release layer having an upper surface for ink-reception, said upper-surface for ink-reception adapted to satisfy at least one of a first structural property and a second structural property, the first and second structural properties being defined below;

b. a paper-based layer which is impregnated with and/or coated with silicone, said paper-based layer being disposed beneath the release layer including at least 50% or at least 60% or at least 80% paper fiber, the paper-based layer configured to contribute to ITM stiffness such that a ratio between (i) a spring constant in the longitudinal direction of the paper-based layer; and a (ii) a spring constant in the longitudinal direction of the ITM is at least 0.5 or at least 0.6 or at least 0.7 or at least 0.8;

c. a grip-layer disposed beneath the paper-based layer, wherein:

A. the paper-based layer has a black upper surface and/or the ITM includes comprising an additional electromagnetic-energy-absorbing layer above the paper layer and below the release layer, said energy-absorbing layer comprising black material;

B. according to the first structural property, a receding contact angle of a droplet of distilled water on said upper surface of said silicone-based release layer is at most 60°;

C. according to the second structural property, for a droplet of distilled water deposited on said upper surface of said silicone-based release layer, a 10 second dynamic contact angle (DCA) is at most 108°.

23 . A method of manufacturing the ITM of any preceding claim , the method comprising:

a. providing a release-layer-including-structure and a paper-layer-including structure wherein:

i. the release-layer-including structure comprises:

A. a sheet of polyethylene terephthalate (PET); and

B. the release layer of the ITM of any preceding claim disposed on the PET sheet;

ii. the paper-layer-including structure includes the paper-based layer of any preceding claim and optionally an additional optional layer;

b. laminating the paper-layer-including structure to the release-layer-including structure by applying an adhesive therebetween, wherein the method is performed so that an adhesion layer of the adhesive is disposed between the release layer of the ITM of any preceding claim and the paper-layer of the ITM of any preceding claim .

24 . The method of manufacturing of claim 23 wherein before the laminating of step (b), the paper-based layer of the release-layer-including structure is coated with and/or impregnated with at least one of epoxy and silicone.

25 . The method of manufacturing of any one of claims 23-24 wherein the a sheet of polyethylene terephthalate (PET) of the release-layer-including structure is coated with a fumed metal.

26 . A printing system, comprising:

a. an ITM according to any one of claims 1-22 , said ITM mounted the ITM on rollers of the printing system;

b. an image-forming station wherein ink images are formed by ink-droplet deposition of an aqueous ink upon a surface of the ITM moving through an image-forming station of the printing system; and

c. an impression-station where the ink images are transferred from the ITM to substrate.

27 . A method of printing using a printing system, comprising

a. providing an ITM according to any one of claims 1-22 ;

b. mounting the ITM on rollers of the printing system so that the ITM passes through multiple stations of the printing system;

c. forming an endless ITM-loop by joining two ends of the ITM to each other;

d. forming ink images by ink-droplet deposition upon a surface of the ITM moving through an image-forming station of the printing system;

e. transporting the ink images on the ITM to an impression station of the printing system; and

f. transferring the ink images to a substrate at an impression station of the printing system.

28 . The method of claim 27 , wherein the ink-droplets comprise an aqueous ink.

29 . The method of either one of claims 27 or 28 , wherein during the forming and transferring, respective portions of the ITM passing through the image-forming station and the impression station are at temperatures of at least 100° C.

30 . The method of any one of claims 27 to 29 , wherein at least a lengthwise majority of the ITM is at a temperature of at least 140° C. during the forming, transporting and transferring.

31. The method of any one of claims 27 to 30 , wherein at least a portion of the ITM is at a temperature of at least 200° C. during at least one of the forming, transporting and transferring.

32 . The method of any one of claims 27 to 31 , wherein the transporting of the ink images from the image-forming station to the impression station is over a distance of at least 3 m, or at least 4 m, or at least 5 m, or at least 6 m.

33 . A method of printing, comprising:

a. providing an intermediate transfer (ITM) of any one of the preceding claims ;

b. mounting the ITM on rollers of a printing system so that the ITM passes through multiple stations of the printing system;

c. forming an endless ITM-loop by joining two ends of the ITM to each other; and

d. rotating the ITM-loop through the multiple stations so that respective portions of the ITM successively pass (i) an image-forming station where ink images are formed by deposition of droplets of an aqueous ink upon an ITM-portion-surface and (ii) an impression station where the ink images are transferred from the ITM to a substrate.