WO2008054638B1

WO2008054638B1 - High flow rate development of photosensitive plates

Info

Publication number: WO2008054638B1
Application number: PCT/US2007/022044
Authority: WO
Inventors: Howard A Fromson; William J Rozell; William J Ryan
Original assignee: Anocoil Corp; Fromson H A; William J Rozell; William J Ryan
Priority date: 2006-10-27
Filing date: 2007-10-15
Publication date: 2008-10-23
Also published as: WO2008054638A2; WO2008054638A3

Abstract

A process for developing an imaged lithographic printing plate, including the step of delivering developing fluid to the plate at a high volumetric flow rate for a short dwell time such that the non-image is completely solubilized while the image remains unaffected by the developing fluid. At sufficient volumetric flow rate, the developer solution at the target area is constantly displaced during the development time, whereby no boundary layer forms on and travels with the plate during the development time and thus the target area is always in contact with fresh developer solution.

Claims

29AMENDED CLAIMS received by the International Bureau on 30 June 2008 (30.06.08)Claims

1. A method of developing a planographic printing plate having a plate substrate and an imaged coating covering the substrate and defining regions that are relatively insoluble in a developer solution and regions that are relatively soluble in the developer solution, characterized by applying a continual flow of fresh developer solution onto each unit area of the coating for a specified dwell time such that the relatively soluble regions are solubilized and removed from the substrate while the relatively insoluble regions remain unaffected.

2. The method of claim 1 , wherein the flow covers each unit area of the coating with a turbulent flow of fresh developer solution for the specified dwell time.

3. The method of claims 1 or 2, wherein the specified dwell time for each unit area is less than about 10 seconds and immediately following said dwell time the flowing developer on each unit area is removed.

4. The method of claims 1 or 2, wherein the entire coating is covered simultaneously with said turbulent flow for a dwell time of less than about 10 seconds.

5. The method of claims 1 or 2, wherein successive areas of the coating are covered with said turbulent flow until the entire coating has been covered.

6. The method of claim 5, wherein the turbulent flow is produced by a pressurized spray of developer solution impinging on the coating. 30

7. The method of claim 6, wherein the spray is at sufficient volume and pressure to continuously push spent developer solution off the plate and thereby maintain fresh developer solution in contact with the coating.

8. The method of claim 6, wherein each unit area of the coating is subjected to said spray for a period of 1-5 seconds.

9. The method of claims 1 or 2, wherein each square cm of plate area is flooded with about 2-5 cc of a turbulent flow of fresh developer solution.

10. The method of claims 1 or 2, wherein successive areas of the coating are covered with said turbulent flow until the entire coating has been covered; each square cm of plate unit area is flooded with about 2-5 cc of a turbulent flow of fresh developer solution for about 1-5 seconds local dwell time; the turbulent flow is at sufficient pressure to continuously push spent developer solution off the plate and thereby maintain fresh developer solution in contact with the coating throughout said local dwell time, without forming a boundary layer; and after each unit area of the plate is covered for said local dwell time, any residual developer solution remaining on said unit area is immediately removed to avoid a residual film of developer solution.

11. The method of claim 10, wherein said residual developer solution is removed by at least one of a nip roller or squeegee.

12. The method of claims 1 or 2, wherein the plate is transported through a turbulent bath of developer solution.

13. The method of claims 1 or 2, wherein the plate has a length and a width and the method comprises providing a continuous flow of fresh developer solution against a target area of the coating over the width of the plate, at a volumetric flow rate and with turbulence sufficient to flood the target area and prevent the formation of a boundary layer thereon.

14. The method of claim 13, wherein the target area is less than about 25% of the total area of the plate; and the plate is transported beneath a flow of said developer solution that impinges transversely on the plate.

15. The method of claim 14, wherein the flow is a continuous spray.

16. The method of claim 14, wherein the flow is a continual spray.

17. The method of claims 1 or 2, wherein any given area of the plate is subjected to said flow, for a dwell time of less than about 10 seconds.

18. The method of claim 14, wherein after impinging on a given plate, a given unit volume of developer solution is pushed off said given plate by a subsequent flow of developer solution; the developer solution pushed off the plate is captured and combined with a source volume of fresh developer solution; and said source volume of developer solution is recycled and delivered as fresh developer flow against a target area of coating on another plate. 32

19. The method of claim 18, including providing a replenishment flow of developer solution to said source volume to make up for at least plate drag out and dissolution reactions with the coating.

20. The method of claims 1 or 2, wherein the plate has a length and a width and said method comprises directing a flow of fresh alkaline developer solution onto successive target areas of the coating extending the width of the plate, at a volumetric flow rate sufficient to create turbulence at the surface of the target area, thereby constantly displacing spent developer solution on a given target area with fresh developer while the flow is directed onto said given target area.

21. The method of claim 20, wherein the plate is supported on a flat surface; an array of discharge devices is spaced from and spans the width of the plate; the array produces a pattern of alkaline developer solution that impinges on the plate in a target area; and the plate and the array move relative to each other at a constant speed.

22. The method of claim 21 , wherein said discharge devices are nozzles spaced apart along the width of the plate; and said nozzles discharge developer solution at a pressure of at least 15 psi.

23. The method of claims 1 or 2, including transporting the plate on a linear path in a transport direction at a constant speed and subjecting successively overlapping target areas of the imaged coating to a turbulent flow of alkaline developer solution for a local dwell time long enough to remove essentially all of the relatively 33

soluble regions while short enough to retain at least about 99% of the relatively insoluble regions.

24. The method of claim 23, wherein a boundary layer of developer solution never forms on the coating while the plate is transported.

25. The method of claim 24, wherein successive areas of the coating are covered with said turbulent flow until the entire coating has been covered; each square cm of plate unit area is flooded with about 2-5 cc of a turbulent flow of fresh developer solution for about 1-5 seconds local dwell time; the turbulent flow is at sufficient pressure to continuously push spent developer solution off the plate and thereby maintain fresh developer solution in contact with the coating throughout said local dwell time; and after each unit area of the plate is covered for said local dwell time, any residual developer solution remaining on said unit area is immediately removed.

26. The method of claim 25, wherein said residual developer solution is removed by at least one of a nip roller or squeegee.

27. The process of claims 1 or 2, wherein the flow rate is at least about 0.2 cc per cm² per second.

28. The process of claim 27, wherein immediately following said dwell time, substantially all developer fluid on said unit area is removed.

29. The method of claims 1 or 2, wherein the developer solution is applied by flooding. 34

30. The method of claims 1 or 2, wherein a brush saturated with developer solution applies developer solution to the plate without forming a boundary layer.

31. The method of claims 1 or 2, wherein the developer solution is essentially a mono component solution.

32. The method of claim 31 , wherein the developer solution is an alkaline developer solution.

33. The method of claim 32, wherein the developer solution is applied to a positive working plate having a coating comprising an inhibited phenolic resin that is sensitive to infrared radiation.

34. The method of claim 33, wherein the developer solution has less than 4 percent benzyl alcohol as the mono component.

35. The method of claims 1 or 2, wherein the developer solution is applied to a negative working plate.

36. The method of claim 15, wherein the coating comprises a photopolymerizable composition sensitive to infrared radiation.

37. The method of claims 1 or 2, wherein during at least a portion of the dwell time, an impulse force is applied to dislodge solubilized coating material.

38. The method of claim 37, wherein the developer solution is applied in a spray and the spray has sufficient impulse force to dislodge solubilized coating material. 35

39. The method of claim 37, wherein after the flowing developer solution is removed, a brush contacts the plate to clean out material that may be trapped in said substrate.

40. The method of claim 37, including a wiping of the coating to dislodge solubilized material while the developer solution is being applied.

41. The method of claims 1 or 2, wherein, the developer solution is applied by a spray at a pressure exceeding 50 psi and a flow rate on the plate exceeding 0.5 cc per cm² per second; and after the flowing developer solution is removed, a brush contacts the plate to clean out material that may be trapped in said substratβi

42. The method of claims 1 or 2, wherein the dwell time is in the range of 2-5 seconds.

43. The method of claim 25, wherein the plate is conveyed at a speed in the range of 3-10 feet per minute.