Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making printing plates
Reexamination Certificate
1999-02-25
2001-05-29
Le, Hoa Van (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making printing plates
C430S271100, C430S944000, C101S457000, C101S458000, C101S459000, C101S462000, C101S467000, C427S447000, C427S452000, C427S454000, C427S455000, C427S456000, C427S453000
Reexamination Certificate
active
06238843
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to planographic printing, especially to lithographic printing. More particularly, this invention relates to a planographic printing member and a method for its preparation.
BACKGROUND OF THE INVENTION
Lithographic processes involve establishing image (printing) and non-image (non-printing) areas on a substrate, substantially on a common plane. When such processes are used in printing industries, non-image areas and image areas are arranged to have different affinities for printing ink. For example, non-image areas may be generally hydrophilic or oleophobic and image areas may be oleophilic. In “wet” lithographic printing, a dampening or fountain (water-based) liquid is applied initially to a plate prior to application of ink so that it adheres to the non-image areas and repels oil based inks therefrom. In “dry” printing, ink is repelled from non-image areas due to their release property.
There are numerous known processes for creating image and non-image areas. Recently, much work has been directed towards processes that use laser imaging, in view of the ease with which lasers can be controlled digitally.
For example, Lewis, U.S. Pat. No. 5,339,737 (Presstek) describes lithographic printing plates suitable for imaging by means of laser devices that emit in the near-infrared region. One plate described includes a substrate having an oleophilic layer, an ablatable layer over the oleophilic layer and a top hydrophilic layer. Imagewise laser exposure ablates areas of the ablatable layer which areas (together with the portions of the hydrophilic layer fixed thereto) are removed. A plate for use in wet lithographic printing, which is described in U.S. Pat. No. 5,339,737, has a hydrophilic layer derived from polyvinyl alcohol, which is a water-soluble polymer. As a result, the hydrophilic layer gradually dissolves into the water-based dampening or fountain solution, thereby leading to a gradual acceptance of ink by non-image areas. Consequently, the number of prints obtainable from such a plate is severely limited.
Verburgh, WO94/18005 (Agfa) describes a substrate coated with an ink receptive layer over which an ablatable layer is provided. A hardened hydrophilic layer comprising titania, polyvinyl alcohol, tetramethylorthosilicate and a wetting agent is provided over the ablatable layer. Disadvantageously, the hydrophilic layer needs to be hardened at an elevated temperature for a period of at least several hours and for some cases up to a week (see Hauquier, U.S. Pat. No. 5,462,833) in order to provide a viable product.
SUMMARY OF THE INVENTION
The present invention addresses problems associated with planographic printing members and with methods for their preparation.
According to the invention, there is provided a method of preparing a planographic printing member comprising a support, an ablatable layer and a hydrophilic layer, said method including forming said hydrophilic layer by application of a material (hereinafter “said hydrophilic material”) in a dry deposition technique.
Preferably, said planographic printing member is a printing plate.
Said hydrophilic layer may be applied over said support, suitably so that it is between the support and said ablatable layer or it may be applied so that said ablatable layer is between the support and said hydrophilic layer. The latter described arrangement is preferred. Preferably, the planographic printing member is arranged such that, on ablation of said ablatable layer, areas of the hydrophilic layer over areas of the ablatable layer that are ablated are removed.
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patent: 4414059 (1983-11-01), Blum et al.
patent: 4526839 (1985-07-01), Herman et al.
patent: 5339737 (1994-08-01), Lewis et al.
patent: 5382964 (1995-01-01), Schneider
patent: 5462833 (1995-10-01), Hauquier et al.
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patent: 5853928 (1998-12-01), Kim
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Derwent Abstract: 1993-332166, On Line Derwent Abstract. File DWPI, English abstract of JP 0524126 A, Sep. 21, 1993.*
N. Nechiporenko, Proc. 15th. Inter. Conf. Print. Res. Ipet., Lillehamner, Norway, Jun. 1979, Pentch Press, London, p. 139-148.
McCullough Christopher David
Ray Kevin Barry
Kodak Polychrome Graphics LLC
Le Hoa Van
Lee Sin J.
Ratner & Prestia
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