Polymeric printing form and process for preparing the same with curable composiiton having a multifunctional urethane

Patent metadata

Field	Value
Publication number	US-2016288479-A1
Application number	US-201615078228-A
Country	US
Kind code	A1
Filing date	Mar 23, 2016
Priority date	Apr 2, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

The invention pertains to a printing form and a process for preparing a polymeric printing form from a curable composition that includes a multifunctional urethane in a specified reactive group equivalent weight range, and an initiator. The process includes coating the curable composition onto a supporting substrate, such as a print cylinder, to form a layer, curing the layer with heat or by exposure to actinic radiation, and engraving the resulting cured layer to form at least one printing cell in the cured layer. The process prepares novel polymeric printing forms, particularly novel polymeric gravure printing forms, having a cured polymer-based composition layer that is engravable, resistant to solvent inks, and capable of printing gravure-quality images. The present invention shortens the time to prepare gravure printing cylinders and removes the need for and disposal of toxic heavy metals such as copper and chrome associated with conventional gravure print cylinder preparation.

First claim

What is claimed is:

1 . A process for preparing a printing form comprising:
a) applying a layer of a curable composition comprising a multifunctional urethane, and an initiator, and optionally a reactive diluent, wherein the curable composition has an reactive group equivalent weight between 250 and 450 g/equivalent, based upon the weighted average of the multifunctional urethane and the optional reactive diluent if present, onto a supporting substrate; b) exposing the layer of the curable composition to actinic radiation or heat to form a cured layer; and c) engraving at least one cell in the cured layer resulting from step b).

2 . The process of claim 1 wherein the multifunctional urethane has two or more ethylenically unsaturated groups, and the curable composition further comprises one or more reactive diluents having two or more ethylenically unsaturated groups, and the reactive group equivalent weight of the curable composition is the weighted average of the reactive group equivalent weights of the one or more reactive diluents and the multifunctional urethane, and is between 250 and 450 g/equivalent.

3 . The process of claim 1 wherein the multifunctional urethane is a multifunctional acrylated urethane having two or more (meth)acrylate groups, and the reactive group equivalent weight is an acrylate equivalent weight that is between 250 and 450 g/equivalent.

4 . The process of claim 1 wherein the curable composition further comprises one or more resin modifiers independently selected from the reactive diluent, monofunctional diluents, monomers, auxilliary resin modifying compounds, or combinations thereof.

5 . The process of claim 1 wherein the multifunctional urethane comprises one or more multifunctional acrylated urethanes having two or more (meth)acrylate groups, the initiator is a photoinitiator; and the optional reactive diluent comprises one or more reactive diluents having two or more (meth)acrylate groups, and the reactive group equivalent weight of the composition is an acrylate equivalent weight that is the weighted average of the acrylate equivalent weights of the one or more reactive diluents and the multifunctional acrylated urethane, and is between 250 and 450 g/equivalent.

6 . The process of claim 1 wherein the multifunctional urethane comprises one or more multifunctional acrylated urethanes having two or more (meth)acrylate groups, at least one reactive diluent having two or more (meth)acrylate groups, and an auxilliary resin modifying compound having two or more (meth)acrylate groups, and wherein the reactive group equivalent weight of the curable composition is an acrylate equivalent weight that is the weighted average of the acrylate equivalent weights of the one or more multifunctional acrylated urethanes, the at least one reactive diluent, and the auxilliary resin modifying compound, and is between 250 and 450 g/equivalent.

7 . The process of claim 1 wherein the curable composition further comprises at least one reactive diluent that has a viscosity of less than or equal to 300 cp and is selected from the group of difunctional (meth)acrylate monomers, difunctional (meth)acrylate oligomers, trifunctional (meth)acrylate monomers, trifunctional (meth)acrylate oligomers, and combinations thereof.

8 . The process of claim 1 wherein the supporting substrate is in the form of a cylinder or sheet.

9 . The process of claim 1 wherein the supporting substrate is a gravure print cylinder.

10 . The process of claim 1 wherein the applying step comprises coating the curable composition having a viscosity between 200 to 20000 cp to form a layer having a thickness between 50.8 and 3810 micrometers.

11 . The process of claim 10 wherein coating the curable composition is selected from spin coating, dip coating, slot die coating, roller coating, extrusion coating, brush coating, ring coating, powder coating, and blade coating.

12 . The process of claim 1 wherein the initiator is a photoinitiator and the exposing step b) comprises exposing the curable composition layer to actinic radiation selected from ultraviolet radiation, visible radiation, and electron-beam radiation.

13 . The process of claim 12 wherein the actinic radiation is ultraviolet radiation having an energy density between 1000 and 30000 mJoules/cm 2 .

14 . The process of claim 1 wherein after the exposing step, the process further comprising polishing an exterior surface of the cured layer that is opposite the supporting substrate providing the exterior surface with an Rz value less than 2.54 micron.

15 . The process of claim 1 wherein the engraving step is selected from electromechanical engraving or laser engraving.

16 . The process of claim 1 wherein after the exposing step the cured layer of the composition has a hardness of 30 to 200 megaPascals.

17 . A process for gravure printing with a printing form comprising:
a) preparing the printing form having a cured layer according to the process of claim 1 ; b) applying an ink to the at least one cell; and c) transferring ink from the cell to a printable substrate,
wherein the cured layer swells 15% based on weight of the layer.

18 . A printing form comprising a supporting substrate and a print surface adjacent to the supporting substrate, wherein the print surface is a cured layer of a curable composition comprising a multifunctional urethane, and an initiator, and optionally a reactive diluent, wherein the composition is characterized by a reactive group equivalent weight of the multifunctional urethane and the optional reactive diluent that is between 250 and 450 g/equivalent.

19 . A printing form precursor comprising:
a supporting substrate; and a layer of a curable composition adjacent to the supporting substrate, wherein the curable composition comprises a multifunctional urethane, and an initiator, and optionally a reactive diluent, wherein the curable composition has reactive group equivalent weight between 250 and 450 g/equivalent, based upon the multifunctional urethane and the optional reactive diluent.

20 . A curable multifunctional urethane polymer for use as a printing surface in a printing form comprising:
a) 30 to 95 wt % of at least one multifunctional urethane having two or more reactive groups; b) 0.1 to 10 wt % of at least one initiator; c) 0 to 40 wt % of one or more reactive diluents having two or more reactive groups; d) 0 to 20 wt % of one or more monofunctional diluents; e) 0 to 20 wt % of one or more monomers; f) 0 to 35 wt % of one or more auxilliary resin modifying compounds;
wherein the total of the reactive diluents, monofunctional diluents, monomers, and auxilliary resin modifying compounds is no more than 40 wt % of the curable composition;
g) 0 to 55 wt % of particulate filler selected from nanoparticles, microparticles, and combinations thereof; and,
optionally, upto 10 wt % total of one or more of additives independently selected from adhesion promotors, slip agents, flow and leveling agents, wetting agents, plasticizers, flexibilizing agents, stabilizers, antioxidants, or dispersants;
wherein the wt % is based on the total of the solid components in the curable composition;
wherein the curable composition has a reactive group equivalent weight of the at least one multifunctional urethane and the one or more reactive diluents and, is 250 to 450 g/equivalent,
wherein the curable composition forms a cured layer that has a hardness of at least 30 megaPascals on a supporting substrat

Assignees

• Du Pont

Inventors

• Shuey Steven W
• Lungu Adrian
• Shah Mukesh C
• Figuly Garret D

Classifications

• B41N1/22

  made of other substances · CPC title

• C08L35/02

  Homopolymers or copolymers of esters (C08L35/06, C08L35/08 take precedence) · CPC title

• C08L2205/06

  having improved processability or containing aids for moulding methods · CPC title

• C08F122/22

  Esters containing nitrogen · CPC title

• B41C1/05

  Heat-generating engraving heads, e.g. laser beam, electron beam · CPC title