# US 9,040,226 B2 · Method of improving print performance in flexographic printing plates

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- Number: US 9,040,226 B2
- Document ID: US9040226B2
- Status: Granted
- Kind: B2
- Application number: 13/892,406
- Filed: 2013-05-13
- Published: 2014-11-13
- Granted: 2015-05-26
- Earliest claimed: 2013-05-13
- Applicants: MacDermid Printing Solutions, LLC
- Inventors: Chouaib Boukaftane
- Web page: https://patentgrep.com/patent/US9040226B2

## CPC

- G03F 7/20: Exposure; Apparatus therefor (photographic printing apparatus for making copies G03B27/00)
- G03F 7/2004: {characterised by the use of a particular light source, e.g. fluorescent lamps or deep UV light}
- G03F 7/40: Treatment after imagewise removal, e.g. baking
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

A method of tailoring the shape of a plurality of relief printing dots created in a photosensitive printing blank during a platemaking process including the steps of: (a) selectively exposing at least one photocurable layer to a source of actinic radiation to selectively crosslink and cure the at least one photocurable layer; and (b) developing the exposed at least one photocurable layer to reveal the relief image therein, said relief image comprising the plurality of relief printing dots. The source of actinic radiation comprises a source of UV light in the UV-A range and a source of light in the UV-C range. The at least one photocurable layer is simultaneously exposed to the source of UV light in the UV-A range and the source of UV light in the UV-C range to produce printing dots having at least one desired geometric characteristic.

## Claims

### Claim 1

A method of tailoring the shape of a plurality of relief printing dots created in a photosensitive printing blank during a platemaking process, said photosensitive printing blank comprising at least one photocurable layer disposed on a backing layer, the method comprising the steps of:
a) selectively exposing the at least one photocurable layer to a source of actinic radiation to selectively crosslink and cure portions of the at least one photocurable layer; and
b) developing the exposed at least one photocurable layer to reveal a relief image therein, said relief image comprising the plurality of relief printing dots;
wherein the source of actinic radiation comprises at least one source of UV light in a UV-A range and at least one source of light in a UV-C range, wherein the at least one photocurable layer is simultaneously exposed to the at least one source of UV light in the UV-A range and the at least one source of UV light in the UV-C range;
whereby printing dots are produced having at least one geometric characteristic selected from the group consisting of a desired planarity of a top surface of the relief printing dots, a desired shoulder angle of the relief printing dots and a desired edge sharpness of the relief printing dots.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the UV-A light source is selected from the group consisting of carbon arcs, mercury-vapor arcs, fluorescent lamps, electron flash units, electron beam units, lasers, photographic flood lamps, and UV LEDs.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the UV-A light source emits at wavelengths of between about 300 nm and about 400 nm.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the UV-C light source is selected from the group consisting of low pressure mercury lamps, high pressure mercury lamps, germicidal lamps, and heavy hydrogen lamps.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the UV-C light source emits at a wavelength of between about 200 nm and about 300 nm.

### Claim 6 (depends on 1)

The method according to claim 1, wherein an exposure time of the at least one photocurable layer to the at least one source of UV-C light is between about 30 seconds and about 8 minutes.

### Claim 7 (depends on 6)

The method according to claim 6, wherein the exposure time of the at least one photocurable layer to the at least one source of UV-C light is between about 1 minute and about 5 minutes.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the angle of the relief printing dot shoulder is greater than about 50°.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the edge sharpness of the relief printing dots, defined as the ratio of the radius of curvature re at the intersection of a shoulder and the top of the relief printing dot to the width of the dot's top printing surface p is less than about 5%.

### Claim 10 (depends on 9)

The method according to claim 9, wherein the ratio of re:p is less than about 2%.

### Claim 11 (depends on 1)

The method according to claim 1 wherein the relief printing dots comprise a planarity that is greater than the thickness of the at least one photocurable layer.

### Claim 12 (depends on 1)

The method according to claim 1 wherein the at least one photocurable layer comprises both a photoinitiator which is responsive to UV-A light and a photoinitiator which is responsive to UV-C light or a photoinitiator which is sensitive to both UV-A and UV-C light.