Method for making a negative working, heat-sensitive lithographic printing plate precursor

• US 20060019200A1
• Filed: 06/30/2005
• Published: 01/26/2006
• Est. Priority Date: 07/08/2004
• Status: Active Grant

• Current Assignee: ECO3 BV
• Original Assignee: Agfa-Gevaert N.V.
• Inventors: Vermeersch, Joan, Van Aert, Huub, Kokkelenberg, Dirk
• Granted Patent: US 7,195,861 B2
• Time in Patent Office: Days
• US Class Current: 430/302
• CPC Class Codes: B41C 1/1025 using materials comprising a polymeric matrix containing a polymeric particulate material, e.g. hydrophobic heat coalescing particles
• CPC Class Codes: B41C 2201/02 Cover layers; Protective layers
• CPC Class Codes: B41C 2201/14 characterised by macromolecular organic compounds, e.g. binder, adhesives
• CPC Class Codes: B41C 2210/04 Negative working, i.e. the non-exposed (non-imaged) areas are removed
• CPC Class Codes: B41C 2210/06 Developable by an alkaline solution
• CPC Class Codes: B41C 2210/22 characterised by organic non-macromolecular additives, e.g. dyes, UV-absorbers, plasticisers
• CPC Class Codes: B41C 2210/24 characterised by a macromolecular compound or binder obtained by reactions involving carbon-to-carbon unsaturated bonds, e.g. acrylics, vinyl polymers
• CPC Class Codes: B41M 2205/12 Preparation of material for subsequent imaging, e.g. corona treatment, simultaneous coating, pre-treatments

Abstract

A method for making a heat-sensitive negative-working lithographic printing plate precursor is disclosed comprising the steps of (i) preparing a coating solution comprising hydrophobic thermoplastic polymer particles and a hydrophilic binder; (ii) applying said coating solution on a support having a hydrophilic surface or which is provided with a hydrophilic layer, thereby obtaining an image-recording layer; (iii) drying said image-recording layer; characterized in that said hydrophobic thermoplastic polymer particles have an average particle size in the range from 45 nm to 63 nm, and that the amount of said hydrophobic thermoplastic polymer particles in the image-recording layer is at least 70% by weight relative to the dried image-recording layer.

Claims

1. A method for making a heat-sensitive negative-working lithographic printing plate precursor comprising the steps of

(i) preparing a coating solution comprising hydrophobic thermoplastic polymer particles and a hydrophilic binder;

(ii) applying said coating solution on a support having a hydrophilic surface or which is provided with a hydrophilic layer, thereby obtaining an image-recording layer; and

(iii) drying said image-recording layer;

wherein said hydrophobic thermoplastic polymer particles have an average particle size in the range from 45 nm to 63 nm,

and the amount of said hydrophobic thermoplastic polymer particles in the image-recording layer is at least 70% by weight relative to the weight of the dried image-recording layer.

2. The method according to claim 1 wherein the hydrophobic thermoplastic polymer particles have an average particle size in the range from 45 nm to 55 nm.

3. The method according to claim 1 wherein the amount of hydrophobic thermoplastic polymer particles in the image-recording layer is at least 75% by weight relative to the weight of the image-recording layer.

4. The method according to claim 1 wherein the amount of hydrophobic thermoplastic polymer particles in the image-recording layer is less than or equal to 85% by weight relative to the weight of the image-recording layer.

5. The method according to claim 1 wherein the hydrophobic thermoplastic polymer particles comprise polyethylene, poly(vinyl)chloride, polymethyl(meth)acrylate, polyethyl(meth)acrylate, polvinylidene chloride, poly(meth)acrylonitrile, polyvinylcarbazole, polystyrene or copolymers thereof.

6. The A method according to claim 5 wherein the hydrophobic thermoplastic polymer particles comprise polystyrene or a copolymer comprising polystrene and poly(meth)acrylonitrile.

7. The method according to claim 1 wherein the hydrophilic binder is soluble in an aqueous developer having a pH≧

10.

8. The method according to claim 1 wherein the image-recording layer further comprises an infrared absorbing agent in an amount of at least 6% by weight relative to the weight of the image-recording layer.

9. The method according to claim 1 wherein the coating further comprises at least one compound which provides a visible image after image-wise exposure and development.

10. The method according to claim 1 wherein the coating further comprises at least one compound which provides a visible image after image-wise exposure of the lithographic printing plate precursor but before development.

11. The method according to claim 2, wherein the amount of hydrophobic thermoplastic polymer particles in the image-recording layer is at least 75% by weight relative to the weight of the image-recording layer.

12. The method according to claim 2, wherein the amount of hydrophobic thermoplastic polymer particles in the image-recording layer is less than or equal to 85% by weight relative to the weight of the image-recording layer.

13. The method according claim 2, wherein the hydrophobic thermoplastic polymer particles comprise polyethylene, poly(vinyl)chloride, polymethyl(meth)acrylate, polyethyl(meth)acrylate, polyvinylidene chloride, poly(meth)acrylonitrile, polyvinylcarbazole, polystyrene or copolymers thereof.

14. The method according to claim 2, wherein the hydrophilic binder is soluble in an aqueous developer having a pH≧

10.

15. The method according to claim 2, wherein the image-recording layer further comprises an infrared absorbing agent in an amount of at least 6% by weight relative to the weight of the image-recording layer.

16. The method according to claim 2, wherein the coating further comprises at least one compound which provides a visible image after image-wise exposure and development.

17. The method according to claim 2, wherein the coating further comprises at least one compound which provides a visible image after image-wise exposure of the lithographic printing plate precursor but before development.