Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Patent
1997-12-12
1999-12-21
Batier, Janet
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
4302711, 4302731, 4302781, 430303, 430944, G03C 176
Patent
active
060047232
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to Infra Red (IR) ablateable driographic printing plates generally, and more particularly to IR ablateable driographic printing plates comprised of water based coating layers and methods for producing same.
BACKGROUND OF THE INVENTION
IR ablateable waterless offset printing plates, also termed IR ablateable driographic printing plates, are well known in the art. They typically include, in order, a substrate, e.g. a polyester film, an intermediate oleophilic Infra Red (IR) radiation absorbing layer and a top oleophobic layer.
Offset printing plates, including waterless offset printing plates are selectively exposed to radiation in order to expose a latent image thereon, the image subsequently is selectively colored during printing with oil based inks, typically the four process inks Cyan, Magenta, Yellow and Black (CMYK) inks.
In most IR sensitive driographic plates, the latent image is recorded by ablating the top oleophobic layer and therefore during printing, the oil based inks are repelled by the areas of the top oleophobic layer which have not been ablated during imaging and are not repelled by the oleophilic absorption layer and the substrate revealed in the ablated areas.
Typically, the top ablateable oleophobic layer is composed of silicone (polysiloxane) or a mixture of silicones cross-linked by cross-linking agents deposited on the plate from a solution dissolved in an organic solvent.
For example, naphtha was described as the solvent employed for producing the top ablateable oleophobic layer using one silicone composition in U.S. Pat. No. 5,378,580 to Leenders and using a mixture of silicone solutions with cross linking agents in U.S. Pat. No. 5,310,869 to Lewis et al.
In the prior art, the IR absorption layer of driographic printing plates have been also produced employing organic solvents. For example, published PCT application GB93/01413 to Gutes et al describes the use of a water-alcohol mixture, for producing the IR absorption layer.
Generally speaking, since organic solvents are used in preparing prior art driographic printing plates, the plates are not environmentally friendly.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a waterless Infra Red (IR) ablateable offset printing plate which is produced substantially without using organic solvents.
According to a preferred embodiment of the present invention, the plate is comprised from a substrate coated, in order, by two layers, a water based oleophilic IR absorption layer and a water based IR ablateable oleophobic layer.
According to a second preferred embodiment of the present invention, the plate includes a substrate coated, in order, by three layers, a water based adhesion promoting layer, a water based IR oleophilic layer and a water based IR ablateable oleophobic layer.
The term water based is used herein to indicate that the precursors materials from which each layer is being deposited are dissolved in water and not in an organic solvent or solvents.
According to one aspect of the present invention, water is employed with silicone emulsions and cross-linking agents to produce the top oleophobic layer.
An emulsion as used herein refers to a water insoluble resin substantially homogeneously dispersed in water.
According to another aspect of the present invention, water is employed with suitable resins and suitable IR absorbing materials to produce the IR absorbing oleophilic layer.
According to a further aspect of the present invention, water is employed with suitable resins to produce the adhesion promoting layer.
An advantage of the plates of the present invention is that they are water based and therefore, they are more environmentally friendly than prior art IR ablateable driographic plates.
There is thus provided, according to a preferred embodiment of the present invention, an IR ablateable driographic printing plate comprising, in order a substrate, an IR absorbing layer comprised substantially of a first water based emulsion, and a top IR abl
REFERENCES:
patent: 3907562 (1975-09-01), Crystal
patent: 3961947 (1976-06-01), Wells
patent: 4588674 (1986-05-01), Stewart et al.
patent: 5310869 (1994-05-01), Lewis et al.
patent: 5339737 (1994-08-01), Lewis et al.
patent: 5378580 (1995-01-01), Leenders
patent: 5493971 (1996-02-01), Lewis et al.
Batier Janet
Gilmore Barbara
Scitex Corporatrion Ltd.
LandOfFree
IR ablateable driographic printing plates and methods for making does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with IR ablateable driographic printing plates and methods for making, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and IR ablateable driographic printing plates and methods for making will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-503379