Heat sensitive printing plate precursors

• US 6,487,969 B2
• Filed: 12/05/2000
• Issued: 12/03/2002
• Est. Priority Date: 12/07/1999
• Status: Expired due to Fees

• Current Assignee: Agfa-Gevaert N.V.
• Original Assignee: Agfa-Gevaert N.V.
• Inventors: Obuchowicz, Jacek Paul, Chau, Tu Vinh
• Primary Examiner(s): Funk, Stephen R.
• Application Number:
  US09/730,058
• Publication Number:
  US 20010018877A1
• Time in Patent Office: 728 Days
• Field of Search: 101/454, 101/456, 101/458, 101/459, 101/465, 101/467, 205/127, 205/139, 205/153, 205/201, 205/213, 205/214, 205/229, 205/921, 430/303
• US Class Current: 101/467
• CPC Class Codes: B41C 1/1008 by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials
• CPC Class Codes: B41C 1/1016 characterised by structural details, e.g. protective layers, backcoat layers or several imaging layers
• CPC Class Codes: B41C 2201/02 Cover layers; Protective layers
• CPC Class Codes: B41C 2201/04 Intermediate 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 2210/16 Waterless working, i.e. ink repelling exposed (imaged) or non-exposed (non-imaged) areas, not requiring fountain solution or water, e.g. dry lithography or driography
• 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: B41N 3/00 Preparing for use and conserving printing surfaces
• CPC Class Codes: B41N 3/034 characterised by the electrochemical treatment of the aluminum support, e.g. anodisation, electro-graining; Sealing of the anodised layer; Treatment of the anodic layer with inorganic compounds; Colouring of the anodic layer
• CPC Class Codes: Y10S 205/921 Electrolytic coating of printing member, other than selected area coating

Abstract

A lithographic printing plate precursor comprises an electrochemically grained aluminium substrate, the grained surface of which is coated with a layer of gel-like amorphous colloidal oxides and hydroxides of aluminium and their hydrates incorporating metallic aluminium and inter-metallic aluminium alloys—generally at a level of below 5%—this layer being produced during the electrochemical graining process. The layer is typically present in an amount of from 0.1-20 g/m² and at a layer thickness of 0.1-4.0 μm, the particle sizes in the said layer generally falling in the range of from 10 to 2000 nm. Methods are disclosed for the preparation of said precursors via the electrochemical graining of aluminium substrates. The invention provides lithographic printing plate precursors which may be imagewise exposed by means of a high intensity laser beam to provide printing plates showing high durability on press and giving images which show good resolution and are free from background staining.

Claims

1. A method of making a lithographic printing plate comprising the steps of providing a lithographic printing plate precursor comprising an electrochemically grained aluminium substrate, the grained surface of which is coated with a smut layer comprising amorphous colloidal oxides and hydroxides of aluminium and their hydrates incorporating metallic aluminium and inter-metallic aluminium alloys, and exposing the lithographic printing plate precursor to heat, wherein the smut layer is removed from the substrate by ablation.

2. A method as defined in claim 1 wherein said inter-metallic aluminium alloys comprise alloys of aluminium with at least one of manganese, iron, magnesium, copper, zinc or titanium.

3. A method as defined in claim 1 wherein the level of metallic aluminium and inter-metallic aluminium alloys present in the smut layer does not exceed 5%.

4. A method as defined in claim 1 wherein said smut layer is present in an amount of from about 0.1-20 g/m² and at a layer thickness of from 0.1-4.0 μ

m.

5. A method as defined in claim 1 wherein the particle sizes of said amorphous colloidal oxides and hydroxides of aluminium and their hydrates incorporating metallic aluminium and inter-metallic aluminium alloys range from 10 to 2000 nm in diameter.

6. A method as defined in claim 1 wherein said grained aluminium substrate additionally comprises an anodic layer.

7. A method as defined in claim 1 wherein the lithographic printing plate precursor additionally comprises a top layer comprising an oleophilic material.

8. A method as defined in claim 1 wherein the lithographic printing plate precursor additionally comprises a top layer comprising a hydrophilic material.

9. A method as defined in claim 1 wherein the lithographic printing plate precursor is a driographic printing plate precursor which additionally comprises a top layer comprising an oleophobic polymeric resin.

10. A method as defined in claim 7, 8 or 9 which additionally comprises an intermediate layer below said top layer, said intermediate layer comprising a dynamic release accelerator.